TY - JOUR TI - Designing Multi‐Level Resistance States in Graphene Ferroelectric Transistors AU - Hassanpour Amiri, Morteza AU - Heidler, Jonas AU - Müllen, Klaus AU - Gkoupidenis, Paschalis AU - Asadi, Kamal T2 - Advanced Functional Materials AB - Abstract Conventional memory elements code information in the Boolean “0” and “1” form. Devices that exceed bistability in their resistance are useful as memory for future data storage due to their enhanced memory capacity, and are also a necessity for contemporary applications such as neuromorphic computing. Here, with the aid of an experimentally validated device model, design rules are outlined and more than two stable resistance states in a graphene ferroelectric field‐effect transistor are experimentally demonstrated. The design methodology can be extrapolated for on‐demand introduction of multiple resistance states in ferroelectric transistors for applications both in data storage and neuromorphic computing. DA - 2020/6/2/ PY - 2020/6/2/ DO - 10.1002/adfm.202003085 VL - 30 IS - 34 J2 - Adv Funct Materials LA - en OP - SN - 1616-301X 1616-3028 UR - http://dx.doi.org/10.1002/adfm.202003085 DB - Crossref ER - TY - JOUR TI - Organic materials and devices for brain-inspired computing: From artificial implementation to biophysical realism AU - van de Burgt, Yoeri AU - Gkoupidenis, Paschalis T2 - MRS Bulletin AB - Abstract DA - 2020/8// PY - 2020/8// DO - 10.1557/mrs.2020.194 VL - 45 IS - 8 SP - 631-640 J2 - MRS Bull. LA - en OP - SN - 0883-7694 1938-1425 UR - http://dx.doi.org/10.1557/mrs.2020.194 DB - Crossref ER - TY - JOUR TI - Organic neuromorphic devices: Past, present, and future challenges AU - Tuchman, Yaakov AU - Mangoma, Tanyaradzwa N. AU - Gkoupidenis, Paschalis AU - van de Burgt, Yoeri AU - John, Rohit Abraham AU - Mathews, Nripan AU - Shaheen, Sean E. AU - Daly, Ronan AU - Malliaras, George G. AU - Salleo, Alberto T2 - MRS Bulletin AB - Abstract DA - 2020/8// PY - 2020/8// DO - 10.1557/mrs.2020.196 VL - 45 IS - 8 SP - 619-630 J2 - MRS Bull. LA - en OP - SN - 0883-7694 1938-1425 UR - http://dx.doi.org/10.1557/mrs.2020.196 DB - Crossref ER - TY - JOUR TI - Electrolyte-gated transistors for synaptic electronics, neuromorphic computing, and adaptable biointerfacing AU - Ling, Haifeng AU - Koutsouras, Dimitrios A. AU - Kazemzadeh, Setareh AU - Burgt, Yoeri AU - Yan, Feng AU - Gkoupidenis, Paschalis T2 - Applied Physics Reviews AB - Functional emulation of biological synapses using electronic devices is regarded as the first step toward neuromorphic engineering and artificial neural networks (ANNs). Electrolyte-gated transistors (EGTs) are mixed ionic–electronic conductivity devices capable of efficient gate-channel capacitance coupling, biocompatibility, and flexible architectures. Electrolyte gating offers significant advantages for the realization of neuromorphic devices/architectures, including ultralow-voltage operation and the ability to form parallel-interconnected networks with minimal hardwired connectivity. In this review, the most recent developments in EGT-based electronics are introduced with their synaptic behaviors and detailed mechanisms, including short-/long-term plasticity, global regulation phenomena, lateral coupling between device terminals, and spatiotemporal correlated functions. Analog memory phenomena allow for the implementation of perceptron-based ANNs. Due to their mixed-conductivity phenomena, neuromorphic circuits based on EGTs allow for facile interfacing with biological environments. We also discuss the future challenges in implementing low power, high speed, and reliable neuromorphic computing for large-scale ANNs with these neuromorphic devices. The advancement of neuromorphic devices that rely on EGTs highlights the importance of this field for neuromorphic computing and for novel healthcare technologies in the form of adaptable or trainable biointerfacing. DA - 2020/3// PY - 2020/3// DO - 10.1063/1.5122249 UR - https://doi.org/10.1063/1.5122249 ER - TY - JOUR TI - Multiscale real time and high sensitivity ion detection with complementary organic electrochemical transistors amplifier AU - Romele, Paolo AU - Gkoupidenis, Paschalis AU - Koutsouras, Dimitrios A. AU - Lieberth, Katharina AU - Kovács-Vajna, Zsolt M. AU - Blom, Paul W. M. AU - Torricelli, Fabrizio T2 - Nature Communications AB - Abstract Ions are ubiquitous biological regulators playing a key role for vital processes in animals and plants. The combined detection of ion concentration and real-time monitoring of small variations with respect to the resting conditions is a multiscale functionality providing important information on health states. This multiscale functionality is still an open challenge for current ion sensing approaches. Here we show multiscale real-time and high-sensitivity ion detection with complementary organic electrochemical transistors amplifiers. The ion-sensing amplifier integrates in the same device both selective ion-to-electron transduction and local signal amplification demonstrating a sensitivity larger than 2300 mV V −1 dec −1 , which overcomes the fundamental limit. It provides both ion detection over a range of five orders of magnitude and real-time monitoring of variations two orders of magnitude lower than the detected concentration, viz. multiscale ion detection. The approach is generally applicable to several transistor technologies and opens opportunities for multifunctional enhanced bioelectronics. DA - 2020/7/27/ PY - 2020/7/27/ DO - 10.1038/s41467-020-17547-0 UR - https://doi.org/10.1038/s41467-020-17547-0 ER - TY - JOUR TI - Unveiling the Finite Temperature Physics of Hydrogen Chains via Auxiliary Field Quantum Monte Carlo AU - Liu, Yuan AU - Shen, Tong AU - Zhang, Hang AU - Rubenstein, Brenda T2 - Journal of Chemical Theory and Computation AB - The ability to accurately predict the finite temperature properties of realistic quantum solids is central to uncovering new phases and engineering materials with novel properties. Nonetheless, there remain comparatively few many-body techniques capable of elucidating the finite temperature physics of solids from first principles. In this work, we take a significant step towards developing such a technique by generalizing our previous, fully ab initio finite temperature Auxiliary Field Quantum Monte Carlo (FT-AFQMC) method to model periodic solids and employing it to uncover the finite temperature physics of periodic hydrogen chains. Based upon our calculations of these chains' many-body thermodynamic quantities and correlation functions, we outline their metal-insulator and magnetic ordering as a function of both H-H bond distance and temperature. At low temperatures approaching the ground state, we observe both metal-insulator and ferromagnetic-antiferromagnetic crossovers at bond lengths between 0.5 and 0.75 {\AA}. We then demonstrate how this low-temperature ordering evolves into a metallic phase with decreasing magnetic order at higher temperatures. By comparing the features we observe to those previously seen in one-dimensional, half-filled Hubbard models at finite temperature and in ground state hydrogen chains, interestingly, we identify signatures of the Pomeranchuk effect in hydrogen chains for the first time and show that spin and charge excitations that typically arise at distinct temperatures in the Hubbard model are indistinguishably coupled in these systems. Beyond qualitatively revealing the many-body phase behavior of hydrogen chains, our efforts shed light on the further theoretical developments that will be required to construct the phase diagrams of the more complex transition metal, lanthanide, and actinide solids of longstanding interest to physicists. DA - 2020/// PY - 2020/// DO - 10.1021/acs.jctc.0c00288 VL - 16 IS - 7 SP - 4298-4314 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85088485021&partnerID=MN8TOARS ER - TY - JOUR TI - Polarization of Valence Orbitals by the Intramolecular Electric Field from a Diffuse Dipole-Bound Electron AU - Yuan, Dao-Fu AU - Liu, Yuan AU - Qian, Chen-Hui AU - Kocheril, G. Stephen AU - Zhang, Yue-Rou AU - Rubenstein, Brenda M. AU - Wang, Lai-Sheng T2 - Journal of Physical Chemistry Letters AB - The diffuse electron in a dipole-bound state is spatially well separated from the valence electrons and is known to have negligible effects on the dipole-bound state’s molecular structure. Here, we show that a dipole-bound state is observed in deprotonated 4-(2-phenylethynyl)-phenoxide anions, 348 cm–1 below the anion’s detachment threshold. The photodetachment of the dipole-bound electron is observed to accompany a simultaneous shakeup process in valence orbitals in this aromatic molecular anion. This shakeup process is due to configuration mixing as a result of valence orbital polarization by the intramolecular electric field of the dipole-bound electron. This observation suggests that dipole-bound anions can serve as a new platform to probe how oriented electric fields influence the valence electronic structure of polyatomic molecules. DA - 2020/// PY - 2020/// DO - 10.1021/acs.jpclett.0c02514 VL - 11 IS - 18 SP - 7914-7919 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85091191389&partnerID=MN8TOARS ER - TY - JOUR TI - Observation of a π -Type Dipole-Bound State in Molecular Anions AU - Yuan, Dao-Fu AU - Liu, Yuan AU - Qian, Chen-Hui AU - Zhang, Yue-Rou AU - Rubenstein, Brenda M. AU - Wang, Lai-Sheng T2 - Physical Review Letters AB - We report the observation of a $\ensuremath{\pi}$-type dipole-bound state ($\ensuremath{\pi}$-DBS) in cryogenically cooled deprotonated 9-anthrol molecular anions ($9{\mathrm{AT}}^{\ensuremath{-}}$) by resonant two-photon photoelectron imaging. A DBS is observed $191\text{ }\text{ }{\mathrm{cm}}^{\ensuremath{-}1}$ (0.0237 eV) below the detachment threshold, and the existence of the $\ensuremath{\pi}$-DBS is revealed by a distinct ($s+d$)-wave photoelectron angular distribution. The $\ensuremath{\pi}$-DBS is stabilized by the large anisotropic in-plane polarizability of 9AT. The population of the dipole-forbidden $\ensuremath{\pi}$-DBS is proposed to be via a nonadiabatic coupling with the dipole-allowed $\ensuremath{\sigma}$-type DBS mediated by molecular rotations. DA - 2020/// PY - 2020/// DO - 10.1103/PhysRevLett.125.073003 VL - 125 IS - 7 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85090172467&partnerID=MN8TOARS ER - TY - JOUR TI - Observation of a Symmetry-Forbidden Excited Quadrupole-Bound State AU - Liu, Y. AU - Zhu, G.-Z. AU - Yuan, D.-F. AU - Qian, C.-H. AU - Zhang, Y.-R. AU - Rubenstein, B.M. AU - Wang, L.-S. T2 - Journal of the American Chemical Society AB - We report the observation of a symmetry-forbidden excited quadrupole-bound state (QBS) in the tetracyanobenzene anion (TCNB–) using both photoelectron and photodetachment spectroscopies of cryogenically-cooled anions. The electron affinity of TCNB is accurately measured as 2.4695 eV. Photodetachment spectroscopy of TCNB– reveals selected symmetry-allowed vibronic transitions to the QBS, but the ground vibrational state was not observed because the transition from the ground state of TCNB– (Au symmetry) to the QBS (Ag symmetry) is triply forbidden by the electric and magnetic dipoles and the electric quadrupole. The binding energy of the QBS is found to be 0.2206 eV, which is unusually large due to strong correlation and polarization effects. A centrifugal barrier is observed for near-threshold autodetachment, as well as relaxations from the QBS vibronic levels to the ground and a valence excited state of TCNB–. The current study shows a rare example where symmetry selection rules, rather than the Franck–Condon principle, govern vibronic transitions to a nonvalence state in an anion. DA - 2020/// PY - 2020/// DO - 10.1021/jacs.0c10552 VL - 142 IS - 47 SP - 20240-20246 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85096609610&partnerID=MN8TOARS ER - TY - JOUR TI - Finite temperature auxiliary field quantum Monte Carlo in the canonical ensemble AU - Shen, Tong AU - Liu, Yuan AU - Yu, Yang AU - Rubenstein, Brenda T2 - Journal of Chemical Physics AB - Finite temperature auxiliary field-based Quantum Monte Carlo methods, including Determinant Quantum Monte Carlo (DQMC) and Auxiliary Field Quantum Monte Carlo (AFQMC), have historically assumed pivotal roles in the investigation of the finite temperature phase diagrams of a wide variety of multidimensional lattice models and materials. Despite their utility, however, these techniques are typically formulated in the grand canonical ensemble, which makes them difficult to apply to condensates like superfluids and difficult to benchmark against alternative methods that are formulated in the canonical ensemble. Working in the grand canonical ensemble is furthermore accompanied by the increased overhead associated with having to determine the chemical potentials that produce desired fillings. Given this backdrop, in this work, we present a new recursive approach for performing AFQMC simulations in the canonical ensemble that does not require knowledge of chemical potentials. To derive this approach, we exploit the convenient fact that AFQMC solves the many-body problem by decoupling many-body propagators into integrals over one-body problems to which non-interacting theories can be applied. We benchmark the accuracy of our technique on illustrative Bose and Fermi Hubbard models and demonstrate that it can converge more quickly to the ground state than grand canonical AFQMC simulations. We believe that our novel use of HS-transformed operators to implement algorithms originally derived for non-interacting systems will motivate the development of a variety of other methods and anticipate that our technique will enable direct performance comparisons against other many-body approaches formulated in the canonical ensemble. DA - 2020/// PY - 2020/// DO - 10.1063/5.0026606 VL - 153 IS - 20 SP - 204108 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85097038269&partnerID=MN8TOARS ER - TY - JOUR TI - Surface pretreatment and deposition temperature dependence of MgO epitaxy on GaN by thermal atomic layer deposition T2 - Journal of Crystal Growth AB - We report on the structural properties of MgO films deposited on GaN templates on sapphire substrates via atomic layer deposition (ALD). Analysis of the crystal quality and structure as a function of surface treatment and growth temperature are presented. Our results indicate deposition temperatures greater than 250 °C are preferable for achieving a high quality MgO thin film. Rotational scans of the samples show a six-fold symmetry at all deposition temperatures, indicating the existence of two rotational symmetric MgO crystal domains on the GaN surface, which were confirmed using electron backscatter diffraction. DA - 2020/4/15/ PY - 2020/4/15/ DO - 10.1016/j.jcrysgro.2020.125568 UR - http://dx.doi.org/10.1016/j.jcrysgro.2020.125568 ER - TY - JOUR TI - Low background doping in AlInN grown on GaN via metalorganic vapor phase epitaxy AU - Borovac, Damir AU - Sun, Wei AU - Peart, Matthew R. AU - Song, Renbo AU - Wierer, Jonathan J., Jr. AU - Tansu, Nelson T2 - Journal of Crystal Growth AB - Nearly lattice-matched and unintentionally doped AlInN films with low background doping grown via metalorganic vapor phase epitaxy on GaN/sapphire are investigated. The lattice-matched condition is verified with x-ray diffraction (XRD), and the films exhibit typical morphological characteristics for AlInN. The optical constants (nr & k) and thicknesses of the AlInN films are determined via spectroscopic ellipsometry, finding an nr ~ 2.2 at 500 nm and a bandgap of ~4.366 eV. Temperature-dependent Hall measurements in the Van der Pauw configuration are performed for temperatures from 80 K up to 350 K, and a low background doping concentration (n ~ 3 × 1017 cm−3) and high electron mobility (μe ~ 320 cm2/V∙s) are found at room temperature. Simulations are performed to determine the influence of the 2-D electron gas (2DEG) caused by polarization fields from the GaN/AlInN interface and validate the Hall measurements. Thus, this work shows the potential of achieving high-quality AlInN films with low background doping densities for use in power electronic devices and deep-ultraviolet light-emitting diodes. DA - 2020/10// PY - 2020/10// DO - 10.1016/j.jcrysgro.2020.125847 UR - https://doi.org/10.1016/j.jcrysgro.2020.125847 ER - TY - JOUR TI - Electrical properties of MgO/GaN metal-oxide-semiconductor structures T2 - Solid-State Electronics AB - Electrical properties of metal-oxide semiconductor (MOS) capacitors were measured with MgO/Al2O3 gate dielectrics deposited by atomic layer deposition (ALD) on GaN. For an Al2O3 (1 nm)/MgO (20 nm) dielectric layer, a leakage current density of 0.25 mA/cm2 at 1 V was measured for the MOS capacitor. A peak capacitance of ~0.1 μF/cm2 was obtained from the C-V measurements with significant hysteresis observed. In addition, a 15-minute forming gas anneal at 450 °C resulted in an increased leakage current density of 1 A/cm2 at 1 V while also increasing the peak capacitance by approximately 30%. To improve the performance, an Al2O3 (20 nm)/MgO (20 nm) dielectric stack was deposited that exhibited a leakage current density of ~1 × 10−5 mA/cm2 at 1 V, which corresponds to ~4 orders of magnitude lower current density than that of the single layer dielectric. Additionally, a 3-layer Al2O3 (10 nm)/MgO (20 nm)/Al2O3 (10 nm) stack also shows a leakage current density reduction of ~4 orders of magnitude, and a reduced density of interface states while remaining a high-k dielectric. The density of interface states was estimated to be between 6.8 × 1011 eV−1 cm−2 and 1.5 × 1012 eV−1 cm−2 for the 3-layer stack using the photo-assisted C-V method. DA - 2020/10// PY - 2020/10// DO - 10.1016/j.sse.2020.107881 UR - http://dx.doi.org/10.1016/j.sse.2020.107881 ER - TY - JOUR TI - Controlled growth of InGaN quantum dots on photoelectrochemically etched InGaN quantum dot templates AU - Muyeed, Syed Ahmed Al AU - Wei, Xiongliang AU - Borovac, Damir AU - Song, Renbo AU - Tansu, Nelson AU - Wierer, Jonathan J., Jr. T2 - Journal of Crystal Growth AB - • InGaN quantum dot (QD) growth templates made by photoelectrochemical (PEC) etching. • Self-assembled (SA) InGaN QD growth is controlled using PEC InGaN QD templates. • SA QDs are smaller sized and higher density on PEC QDs compared to planar GaN. • Atomic force microscopy suggests the SA QDs are aligning to the underlying PEC QDs. • Multiple layers of QDs formed on PEC QD templates exhibit better photoluminescence. Controlled growth of InGaN quantum dots (QDs) using photoelectrochemically (PEC) etched InGaN QD templates is demonstrated. The InGaN QDs are grown by a self-assembly (SA) method using metal-organic chemical vapor deposition on templates consisting of planar GaN and PEC etched InGaN QDs for comparison. The InGaN QD templates are formed using quantum-size-controlled PEC etching of planar InGaN layers on GaN, which produces controlled QD radiuses with a statistical mean (μ) of 17.3 nm and standard deviation (σ) of 6.2 nm, and densities of 1.2 × 10 10 cm −2 . The PEC etched QDs are capped with an AlGaN interlayer and GaN barrier layer to recover a planar surface morphology for subsequent SA growth of QDs. The PEC QD templates behave as seeds via localize strain near the PEC QDs which provide improved control of the SA QD growth. The SA grown QDs on PEC QD templates are smaller and have controlled radiuses with μ = 21.7 nm and σ = 11.7 nm compared to the SA QDs on planar GaN templates with radiuses of μ = 37.8 nm and σ = 17.8 nm. Additionally, the dot densities of the SA QDs on PEC QD templates are ~3 times higher and more closely match the underlying densities of the template (8.1 × 10 9 cm −2 ). Multiple quantum dots (MQDs) are also grown on both templates that consist of 4 periods of SA QDs and AlGaN/GaN interlayer/barrier layers. The MQDs grown on PEC QD templates better retain their planarized smooth surfaces after barrier layer growth, and exhibit ~3 times stronger PL intensity at room temperature compared to MQDs grown on planar GaN. DA - 2020/6// PY - 2020/6// DO - 10.1016/j.jcrysgro.2020.125652 UR - https://doi.org/10.1016/j.jcrysgro.2020.125652 ER - TY - JOUR TI - AlInN/GaN diodes for power electronic devices AU - Peart, Matthew R. AU - Borovac, Damir AU - Sun, Wei AU - Song, Renbo AU - Tansu, Nelson AU - Wierer, Jonathan J., Jr. T2 - Applied Physics Express AB - AlInN/GaN power diodes consisting of a p-type GaN and a 300 nm thick n-type AlInN drift layer are demonstrated. The p–n junction is grown using metalorganic chemical vapor deposition, and the AlxIn1−xN drift layer is lattice-matched to GaN (x ∼ 0.82) with an electron concentration of ∼8 × 1016 cm−3 after correcting for the 2-dimensional electron gas. The diodes exhibit ∼−60 V blocking capability. Under forward bias, the diode has a turn-on voltage of ∼4 V. If experimental challenges are overcome, the ultrawide bandgap and high mobility of an AlInN drift layer could increase the performance of GaN-based power devices. DA - 2020/9/1/ PY - 2020/9/1/ DO - 10.35848/1882-0786/abb180 UR - https://doi.org/10.35848/1882-0786/abb180 ER - TY - JOUR TI - On the thermal stability of nearly lattice-matched AlInN films grown on GaN via MOVPE AU - Borovac, Damir AU - Sun, Wei AU - Song, Renbo AU - Wierer, Jonathan J., Jr. AU - Tansu, Nelson T2 - Journal of Crystal Growth AB - The thermal stability of nearly lattice-matched AlInN films grown via metalorganic vapor phase epitaxy on GaN/sapphire is investigated. The structural and morphological changes of the AlInN layers, as determined by x-ray diffraction (XRD) and atomic force microscopy (AFM), are studied when systematically varying annealing times, temperatures, and ambients to gain a better understanding of the temperature limits of the AlInN films. The samples are annealed either in the growth chamber with the same conditions (gases, pressure, and flow rates) as the original growth conditions of the AlInN samples, or in the XRD under N2. In general, the surface of the AlInN changes at temperatures >850 °C under growth and N2 conditions mostly likely due to a loss of In as determined by AFM. However, the bulk crystal structure of the AlInN remains stable up to temperatures of 950–1050 °C (depending on ambient) as determined by XRD. These findings provide a helpful guide for future experiments involving high-temperatures (790–1050 °C) for subsequent or transition layers during epitaxial growth, and for fabricating device structures employing AlInN layers. DA - 2020/3// PY - 2020/3// DO - 10.1016/j.jcrysgro.2019.125469 UR - http://dx.doi.org/10.1016/j.jcrysgro.2019.125469 ER - TY - JOUR TI - Edge Termination for III-Nitride Vertical Power Devices Using Polarization Engineering AU - Peart, Matthew R. AU - Wierer, Jonathan J. T2 - IEEE Transactions on Electron Devices AB - A method for edge termination utilizing polarization-induced charge for GaN vertical power devices is presented. The polarization edge termination is simulated on a GaN power diode and consists of a 5-nm-thick n-type AlGaN layer on top of a p-type GaN layer that is located at the periphery of the main p-n junction. The spontaneous and piezoelectric polarization present in III-nitrides result in fixed charges at the AlGaN/GaN heterointerface, and the p-GaN layer becomes depleted at this interface under reverse bias. Numerical simulations show that this AlGaN/GaN heterointerface can be engineered to control the depletion region under reverse bias to prevent localization of electric fields and premature avalanche breakdown. Nearly parallel-plate reverse breakdown performance can be achieved. In addition, a simple analytical model based on charge balancing predicts the performance of this edge termination method. DA - 2020/2// PY - 2020/2// DO - 10.1109/ted.2019.2958485 UR - http://dx.doi.org/10.1109/ted.2019.2958485 ER - TY - CONF TI - Single-shot readout of a solid-state spin in a decoherence-free subspace AU - Farfurnik, D. T2 - 11th International Conference On Quantum Dots C2 - 2020/12// C3 - 11th International Conference On Quantum Dots CY - Munich, Germany DA - 2020/12// PY - 2020/12// ER - TY - CONF TI - Arbitrary sequenced spin control of a Quantum Dot strongly coupled to a photonic crystal cavity AU - Farfurnik, Demitry AU - Pettit, Robert M. AU - Luo, Zhouchen AU - Ravan, Shantam M. AU - Waks, Edo T2 - Frontiers in Optics AB - We study the spin dynamics of Quantum Dots under an optical field modulated at the full operation range of a temperature-stabilized electro optical modulator, and spin manipulation capabilities for dots strongly coupled to L3 cavities. C2 - 2020/// C3 - Frontiers in Optics / Laser Science DA - 2020/// DO - 10.1364/fio.2020.fw4c.5 PB - Optica Publishing Group UR - http://dx.doi.org/10.1364/fio.2020.fw4c.5 ER - TY - JOUR TI - Hamiltonian engineering of general two-body spin-1/2 interactions AU - Farfurnik, D. AU - Bar-Gill, N. T2 - Physical Review Research AB - This paper introduces novel rotation pulse sequences, defined by an icosahedral symmetry group, providing the most general engineering capabilities of two-body spin-1/2 interaction terms. Compared to conventional rotations, these sequences offer advantages for creating Zeeman terms essential for magnetic sensing, and could be utilized to generate previously unattainable interaction forms. DA - 2020/1/17/ PY - 2020/1/17/ DO - 10.1103/PhysRevResearch.2.013061 VL - 2 IS - 1 UR - https://doi.org/10.1103/PhysRevResearch.2.013061 ER - TY - JOUR TI - Characterizing spin-bath parameters using conventional and time-asymmetric Hahn-echo sequences AU - Farfurnik, D. AU - Bar-Gill, N. T2 - Physical Review B AB - Spin-bath noise characterization, which is typically performed by multi-pulse control sequences, is essential for understanding most spin dynamics in the solid-state. Here, we theoretically propose a method for extracting the characteristic parameters of a noise source with a known spectrum, using a single modified Hahn-echo sequence. By varying the application time of the pulse, measuring the coherence curves of an addressable spin, and fitting the decay coefficients to a theoretical function derived by us, we extract parameters characterizing the physical nature of the noise. Assuming a Lorentzian noise spectrum, we illustrate this method for extracting the correlation time of a bath of nitrogen paramagnetic impurities in diamond, and its coupling strength to the addressable spin of a nitrogen-vacancy center. Considering a realistic experimental scenario with $5\%$ measurement error, the parameters can be extracted with an accuracy of $\sim 10 \%$. The scheme is effective for samples having a natural homogeneous coherence time ($T_2$) up to two orders of magnitude greater than the inhomogeneous coherence time ($T_2^*$), and mitigates technical noise when further averaging is irrelevant. Beyond its potential for reducing experiment times by an order-of-magnitude, such single-pulse noise characterization could minimize the effects of long time-scale drifts and accumulating pulse imperfections and numerical errors. DA - 2020/3/9/ PY - 2020/3/9/ DO - 10.1103/PhysRevB.101.104306 VL - 101 IS - 10 UR - https://doi.org/10.1103/PhysRevB.101.104306 ER - TY - ER - TY - ER - TY - ER - TY - JOUR TI - 1.2 kV, 10 A, 4H-SiC Bi-Directional Field Effect Transistor (BiDFET) with Low On-State Voltage Drop AU - Kanale, Ajit AU - Cheng, Tzu Hsuan AU - Han, Ki Jeong AU - Baliga, B. Jayant AU - Bhattacharya, Subhashish AU - Hopkins, Douglas T2 - Materials Science Forum AB - Bidirectional power switches are used in matrix-or cyclo-converters and in multistage inverter circuits to facilitate high-frequency AC-to-AC conversion. A new 1.2 kV bidirectional MOSFET (BiDFET) with low on-resistance is achieved and demonstrated using two discrete SiC power MOSFET bare die chips, packaged within a four-terminal custom-designed module. Static and dynamic characterization has been carried out to inspect the on-state and switching behaviour of the BiDFET. The BiDFET is shown to have a low forward voltage drop of 0.6 V at a current of 10 A, which is more than 2.5x smaller than previous Si IGBT and SiC MOSFET based bidirectional switch implementations. DA - 2020/7// PY - 2020/7// DO - 10.4028/www.scientific.net/msf.1004.872 VL - 1004 SP - 872-881 J2 - MSF OP - SN - 1662-9752 UR - http://dx.doi.org/10.4028/www.scientific.net/msf.1004.872 DB - Crossref ER - TY - CONF TI - Dynamic power allocation and virtual cell formation for throughput-optimal vehicular edge networks in highway transportation AU - Pervej, M.F. AU - Lin, S.-C. AB - This paper investigates highly mobile vehicular networks from users' perspectives in highway transportation. Particularly, a centralized software-defined architecture is introduced in which centralized resources can be assigned, programmed, and controlled using the anchor nodes (ANs) of the edge servers. Unlike the legacy networks, where a typical user is served from only one access point (AP), in the proposed system model, a vehicle user is served from multiple APs simultaneously. While this increases the reliability and the spectral efficiency of the assisted users, it also necessitates an accurate power allocation in all transmission time slots. As such, a joint user association and power allocation problem is formulated to achieve enhanced reliability and weighted user sum rate. However, the formulated problem is a complex combinatorial problem, remarkably hard to solve. Therefore, fine-grained machine learning algorithms are used to efficiently optimize joint user associations and power allocations of the APs in a highly mobile vehicular network. Furthermore, a distributed single-agent reinforcement learning algorithm, namely SARL-MARL, is proposed which obtains nearly identical genie-aided optimal solutions within a nominal number of training episodes than the baseline solution. Simulation results validate that our solution outperforms existing schemes and can attain genie-aided optimal performances. C2 - 2020/// C3 - 2020 IEEE International Conference on Communications Workshops, ICC Workshops 2020 - Proceedings DA - 2020/// DO - 10.1109/ICCWorkshops49005.2020.9145348 PB - IEEE UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85090279811&partnerID=MN8TOARS ER - TY - ER - TY - ER - TY - JOUR TI - Optimization of a Sparse Aperture Configuration for Millimeter-wave Computational Imaging AU - Viswanathan, Naren AU - Venkatesh, Suresh AU - Schurig, David T2 - IEEE Transactions on Antennas and Propagation AB - We present two techniques for optimizing the position of transmitter and receiver modules on a sparse aperture for a millimeter-wave computational imaging system. The first technique uses an easily computable spatial representation of the transmitter and receiver array, called the coarray, to ideally distribute the spatial frequency components probed by the imaging setup. The second approach involves maximizing the information added by a complete measurement of the scene by the system. This approach is analogous to the system capacity maximization frequently employed in wireless communication. We show that employing aperture configurations optimized using these two techniques over commonly used standard aperture configurations results in 30% less mean-squared error when used to reconstruct a particular ensemble of 400 arbitrary 2-D objects. Finally, we discuss the similarities and differences between the two optimization strategies in terms of imaging performance and computational speed, including a case when one strategy performs better than the other. DA - 2020/// PY - 2020/// DO - 10.1109/tap.2020.3030946 SP - 1-1 UR - http://dx.doi.org/10.1109/tap.2020.3030946 ER - TY - JOUR TI - A high-speed programmable and scalable terahertz holographic metasurface based on tiled CMOS chips AU - Venkatesh, Suresh AU - Lu, Xuyang AU - Saeidi, Hooman AU - Sengupta, Kaushik T2 - Nature Electronics DA - 2020/12// PY - 2020/12// DO - 10.1038/s41928-020-00497-2 VL - 3 IS - 12 SP - 785-793 UR - http://dx.doi.org/10.1038/s41928-020-00497-2 ER - TY - JOUR TI - A 42-62 GHz Transformer-Based Broadband mm-Wave InP PA With Second-Harmonic Waveform Engineering and Enhanced Linearity AU - Liu, Zheng AU - Sharma, Tushar AU - Chappidi, Chandrakanth Reddy AU - Venkatesh, Suresh AU - Yu, Yiming AU - Sengupta, Kaushik T2 - IEEE Transactions on Microwave Theory and Techniques AB - Indium phosphide (InP) heterojunction bipolar transistors (HBTs) with f t / f max of 350/675 GHz are studied and explored for a linear, high efficiency and broadband power amplifiers (PAs) at mm-wave frequencies. Unlike the conventional transmission-like-based design, this article presents a compact, broadband transformer-based power combining and impedance matching using the waveform engineering approach. We present, for the first time, mm-wave (40-60 GHz) InP topologies incorporating the following: 1) on-chip transformer for broadband, efficient and compact impedance matching and power combining; 2) synthesis of optimal second-harmonic impedance through transformer center tap to achieve high-efficiency differential PA operation; and 3) biasing techniques to reduce AM-PM distortion for linearity enhancement. This work reports a transformer-based push-pull InP PA in 0.25 μm technology across 42-62 GHz demonstrating a peak power added efficiency (PAE) of 39.5% and peak P sat of 20.6 dBm. The PA supports 4 GHz bandwidth at 52 GHz with an EVM of -22.9 dB and an adjacent channel leakage ratio (ACLR) of -32 dBc for an 8 Gb/s QPSK signal at 13.3 dBm average output power. This work presents one of the highest efficiency with wide bandwidth and highest linearity mm-wave PAs in integrated technology. DA - 2020/// PY - 2020/// DO - 10.1109/tmtt.2020.3037092 SP - 1-1 UR - http://dx.doi.org/10.1109/tmtt.2020.3037092 ER - TY - CONF TI - Terahertz to bits and bits to terahertz AU - Sengupta, Kaushik AU - Lu, Xuyang AU - Venkatesh, Suresh AU - Wu, Xue AB - The high millimeter-Wave and Terahertz spectrum above 100 GHz will form the underpinning of a broad set of game-changing future technology including high resolution sensing, imaging, robotics, autonomous systems, and wireless communication. In the last decade, we have seen a tremendous surge in efforts towards enabling chip-scale technology to address signal generation and detection in the THz spectrum. However, there lie several fundamental challenges to translate these efforts into versatile technology that can operate in complex environments that requires properties such as dynamic reconfigurability and rapid adaptability. In this paper, we highlight a new design space that emerges by eliminating the classical block-by-bock design approach. The fundamental principle behind this approach is that the unique wavelength scale at THz (of the order of millimeter/sub-millimeter) is comparable to a typical chip dimension. This wavelength/chip dimension equivalence allows the chip to operate in a new electromagnetic (EM) regime with novel scattering and radiating properties, while the integrated active devices have the ability to actively synthesize, manipulate and sense THz EM fields at sub-wavelength scales. This approach opens up the a new design space that can break many of the trade-offs in the classical design regime. In this paper, we provide design examples that aims towards the ultimate programmable THz sensor/source in silicon-based chips that range from fully integrated chip-scale THz spectroscopes to programmable THz sensors, sources and spatio-temporal modulated arrays for physical layer security. These design examples serve to illustrate the unique opportunities enabled through such a holistic design approach. C2 - 2020/9/23/ C3 - Proceedings of the 7th ACM International Conference on Nanoscale Computing and Communication DA - 2020/9/23/ DO - 10.1145/3411295.3411319 PB - ACM UR - http://dx.doi.org/10.1145/3411295.3411319 ER - TY - CONF TI - Transformer-based broadband mm-wave InP PA across 42--62 GHz with enhanced linearity and second harmonic engineering AU - Liu, Z AU - Sharma, T AU - Chappidi, CR AU - Venkatesh, S AU - Sengupta, K C2 - 2020/// C3 - IEEE MTT-S Int. Microw. Symp. Dig. DA - 2020/// ER - TY - CONF TI - Physically Secure mm-Wave Wireless Links with Spatio-temporal Modulated Arrays AU - Sengupta, Kaushik AU - Lu, Xuyang AU - Venkatesh, Suresh AU - Tang, Bingjun T2 - IEEE C2 - 2020/// C3 - 2020 Third International Workshop on Mobile Terahertz Systems (IWMTS) DA - 2020/// SP - 1-4 ER - TY - CONF TI - Broadband PA architectures with asymmetrical combining and stacked PA cells across 50--70 GHz and 64--110 GHz in 250 nm InP AU - Sharma, T AU - Liu, Z AU - Chappidi, CR AU - Saeidi, H AU - Venkatesh, S AU - Sengupta, K C2 - 2020/// C3 - IEEE MTT-S Int. Microw. Symp. Dig. DA - 2020/// ER - TY - CONF TI - Physically Secure Sub-THz Wireless Links AU - Sengupta, Kaushik AU - Lu, Xuyang AU - Venkatesh, Suresh AU - Tang, Bingjun T2 - IEEE C2 - 2020/// C3 - 2020 IEEE International Conference on Communications Workshops (ICC Workshops) DA - 2020/// SP - 1-7 ER - TY - CONF TI - 29.9 A 4×4 Distributed Multi-Layer Oscillator Network for Harmonic Injection and THz Beamforming with 14dBm EIRP at 416GHz in a Lensless 65nm CMOS IC AB - Integrated high-power THz arrays with beamforming ability can enable new applications in communication, sensing, imaging, and spectroscopy [1]. However, due to the limited power-generation capability of a single source above the device f max [2], efficient spatial power combining from multiple coherent sources becomes necessary to generate mW level of power. To create this 2D array of distributed frequency and phase-locked sources, prior works have shown central LO-signal distribution with local harmonic upconversion [3]. However, this requires high power consumption in the LO distribution. In addition, phase-matching with PVT variations across the sources at the harmonic-radiating THz frequency can be quite challenging. A small Δθ perturbation at the fundamental frequency translates to NΔθ at the radiated N th harmonic, thus corrupting the array beam pattern. Another method to synchronize multiple distributed radiating sources (λ/2 spaced at Nfo) is through a mutual coupling network with active/passive elements in a coupled oscillator array [4], [5]. However, the locking range in these methods is typically narrow (Δf locking ~ f 0 /20 to f 0 /10) and PVT variations can easily cause desynchronization. In such a network, each cell is a self-sustaining oscillator, and the coupling network tries to establish injection signals to force synchronization between these individual free-running oscillators. In this paper, we used a 2D oscillating network with negative G m (-G m ) cells at each node that do not oscillate individually but only collectively, establishing a robust frequency and phase distribution network across the chip for high THz-power generation. By making this network as the lowest layer, we can now separate the locking mechanism and the power-generation sources. This avoids loading and sub-optimal operation of the power sources. The distributed oscillating network at the lowest layer operates at 69.3GHz, and multi-layer local harmonic generation produces a radiated power of -3dBm and +14dBm EIRP at 416GHz in a 4×4 array. C2 - 2020/2// C3 - 2020 IEEE International Solid- State Circuits Conference - (ISSCC) DA - 2020/2// DO - 10.1109/isscc19947.2020.9063076 UR - http://dx.doi.org/10.1109/isscc19947.2020.9063076 ER - TY - JOUR TI - Young Professionals in Space: Transformation Through Democratization [Around the Globe] T2 - IEEE Microwave Magazine AB - Reports on the mission of the Young Professionals in Space (YPinSpace) technical program that was conceived by Dr. Tushar Sharma in 2016. The program’s main objective is to bring world-renowned experts from different fields of space technology to share their experiences with YPs from all over the world under one umbrella. Since its inception, DA - 2020/4// PY - 2020/4// DO - 10.1109/mmm.2019.2963757 UR - http://dx.doi.org/10.1109/mmm.2019.2963757 ER - TY - CONF TI - 4.6 Space-Time Modulated 71-to-76GHz mm-Wave Transmitter Array for Physically Secure Directional Wireless Links AU - Lu, X. AU - Venkatesh, S. AU - Tang, B. AU - Sengupta, K. AB - Security in wireless networks has traditionally been addressed above the physical layer. With the expected proliferation of applications in 5G, the mm-wave spectrum and new network architectures, traditional methods of data encryption may not be scalable for energy-constrained applications. Thus, there has been a surge of interest in physical layer security that aims to impart confidentiality by exploiting the physics of the wireless communication channel without the need for exchanging secret cryptographic keys [1], [2]. The idea of a secure directional wireless link between a TX/RX pair is to preserve the signal information within a secure cone where the intended receiver is located while scrambling signals everywhere else to prevent eavesdropping. In a phased array, the same temporal digital information is fed to all the TX elements, transmitting the same information to all directions albeit at different power levels. This information can be recovered (especially at the side lobes) with a sensitive enough receiver. Spatial modulation with I, Q radiated out through separate antennas, and modulation of parasitic elements can distort the constellation in other directions [3], [4]. However, this one-to-one (bijective) mapping allows potential decoding by the eavesdropper, particularly using various signal processing and machine-learning-based classification techniques. Time modulation in an antenna array can incorporate such physical layer security through careful mapping of symbols to antennas in a time-modulated fashion. C2 - 2020/// C3 - 2020 IEEE International Solid- State Circuits Conference - (ISSCC) DA - 2020/// DO - 10.1109/ISSCC19947.2020.9062929 VL - SP - 86-88 M1 - PB - IEEE UR - http://dx.doi.org/10.1109/isscc19947.2020.9062929 ER - TY - CONF TI - Gigahertz Large-Area-Electronics RF Switch and its Application to Reconfigurable Antennas AU - Wu, Can AU - Ma, Yue AU - Venkatesh, Suresh AU - Mehlman, Yoni AU - Wagner, Sigurd AU - Sturm, James C. AU - Verma, Naveen AB - Future IoT and 5G networks place significant new demands on antennas, where unguided EM waves are generated to access densely distributed sensor nodes. Reconfigurable antennas, capable of changing key parameters (directionality, frequency response, polarization), are starting to play a critical role, but are limited by the assembly of discrete RF components across the large antenna apertures typically desired. This work presents the design, and use in a reconfigurable antenna, of RF switches for 2.4 GHz-band wireless applications, based on large-area-electronics (LAE) zinc-oxide (ZnO) thin-film transistors (TFTs). ZnO TFTs can be fabricated monolithically on meter-scale and flexible substrates, as done in flat panel displays, but where their frequencies have been limited to 10's of MHz. RF switch performance is enabled for ZnO TFTs (fabricated at flex-compatible temp. <; 200°C) via self-aligned processing, thick-composite gate electrodes, breakdown-safe biasing, and resonant operation, leveraging high-Q LAE inductors. Reconfigurable antenna radiation patterns are demonstrated. C2 - 2020/12/12/ C3 - 2020 IEEE International Electron Devices Meeting (IEDM) DA - 2020/12/12/ DO - 10.1109/iedm13553.2020.9372057 PB - IEEE UR - http://dx.doi.org/10.1109/iedm13553.2020.9372057 ER - TY - CONF TI - Terahertz Chip-scale Systems AU - Sengupta, Kaushik AU - Saeidi, Hooman AU - Lu, Xuyang AU - Venkatesh, Suresh AU - Wu, Xue AB - In this paper, we highlight the advances in chip-scale technologies in the terahertz spectrum between 100 GHz and 10 THz, particularly focusing on silicon-based integrated chip technology that can have a transformative impact in wireless communication, sensing and imaging. C2 - 2020/12// C3 - 2020 European Conference on Optical Communications (ECOC) DA - 2020/12// DO - 10.1109/ecoc48923.2020.9333156 PB - IEEE UR - http://dx.doi.org/10.1109/ecoc48923.2020.9333156 ER - TY - JOUR TI - Stretchable, dynamic covalent polymers for soft, long-lived bioresorbable electronic stimulators designed to facilitate neuromuscular regeneration AU - Choi, Yeon Sik AU - Hsueh, Yuan-Yu AU - Koo, Jahyun AU - Yang, Quansan AU - Avila, Raudel AU - Hu, Buwei AU - Xie, Zhaoqian AU - Lee, Geumbee AU - Ning, Zheng AU - Liu, Claire AU - Xu, Yameng AU - Lee, Young Joong AU - Zhao, Weikang AU - Fang, Jun AU - Deng, Yujun AU - Lee, Seung Min AU - Vázquez-Guardado, Abraham AU - Stepien, Iwona AU - Yan, Ying AU - Song, Joseph W. AU - Haney, Chad AU - Oh, Yong Suk AU - Liu, Wentai AU - Yoon, Hong-Joon AU - Banks, Anthony AU - MacEwan, Matthew R. AU - Ameer, Guillermo A. AU - Ray, Wilson Z. AU - Huang, Yonggang AU - Xie, Tao AU - Franz, Colin K. AU - Li, Song AU - Rogers, John A. T2 - Nature Communications AB - Abstract Bioresorbable electronic stimulators are of rapidly growing interest as unusual therapeutic platforms, i.e., bioelectronic medicines, for treating disease states, accelerating wound healing processes and eliminating infections. Here, we present advanced materials that support operation in these systems over clinically relevant timeframes, ultimately bioresorbing harmlessly to benign products without residues, to eliminate the need for surgical extraction. Our findings overcome key challenges of bioresorbable electronic devices by realizing lifetimes that match clinical needs. The devices exploit a bioresorbable dynamic covalent polymer that facilitates tight bonding to itself and other surfaces, as a soft, elastic substrate and encapsulation coating for wireless electronic components. We describe the underlying features and chemical design considerations for this polymer, and the biocompatibility of its constituent materials. In devices with optimized, wireless designs, these polymers enable stable, long-lived operation as distal stimulators in a rat model of peripheral nerve injuries, thereby demonstrating the potential of programmable long-term electrical stimulation for maintaining muscle receptivity and enhancing functional recovery. DA - 2020/11// PY - 2020/11// DO - 10.1038/s41467-020-19660-6 VL - 11 IS - 1 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85096525977&partnerID=MN8TOARS ER - TY - JOUR TI - Wireless, battery-free subdermally implantable photometry systems for chronic recording of neural dynamics AU - Burton, A. AU - Obaid, S.N. AU - Vázquez-Guardado, A. AU - Schmit, M.B. AU - Stuart, T. AU - Cai, L. AU - Chen, Z. AU - Kandela, I. AU - Haney, C.R. AU - Waters, E.A. AU - Cai, H. AU - Rogers, J.A. AU - Lu, L. AU - Gutruf, P. T2 - Proceedings of the National Academy of Sciences of the United States of America AB - Recording cell-specific neuronal activity while monitoring behaviors of freely moving subjects can provide some of the most significant insights into brain function. Current means for monitoring calcium dynamics in genetically targeted populations of neurons rely on delivery of light and recording of fluorescent signals through optical fibers that can reduce subject mobility, induce motion artifacts, and limit experimental paradigms to isolated subjects in open, two-dimensional (2D) spaces. Wireless alternatives eliminate constraints associated with optical fibers, but their use of head stages with batteries adds bulk and weight that can affect behaviors, with limited operational lifetimes. The systems introduced here avoid drawbacks of both types of technologies, by combining highly miniaturized electronics and energy harvesters with injectable photometric modules in a class of fully wireless, battery-free photometer that is fully implantable subdermally to allow for the interrogation of neural dynamics in freely behaving subjects, without limitations set by fiber optic tethers or operational lifetimes constrained by traditional power supplies. The unique capabilities of these systems, their compatibility with magnetic resonant imaging and computed tomography and the ability to manufacture them with techniques in widespread use for consumer electronics, suggest a potential for broad adoption in neuroscience research. DA - 2020/// PY - 2020/// DO - 10.1073/pnas.1920073117 VL - 117 IS - 6 SP - 2835-2845 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85079324763&partnerID=MN8TOARS ER - TY - JOUR TI - Modeling cross-regulatory influences on monolignol transcripts and proteins under single and combinatorial gene knockdowns in Populus trichocarpa AU - Matthews, Megan L. AU - Wang, Jack P. AU - Sederoff, Ronald AU - Chiang, Vincent L. AU - Williams, Cranos M. T2 - PLOS Computational Biology AB - Accurate manipulation of metabolites in monolignol biosynthesis is a key step for controlling lignin content, structure, and other wood properties important to the bioenergy and biomaterial industries. A crucial component of this strategy is predicting how single and combinatorial knockdowns of monolignol specific gene transcripts influence the abundance of monolignol proteins, which are the driving mechanisms of monolignol biosynthesis. Computational models have been developed to estimate protein abundances from transcript perturbations of monolignol specific genes. The accuracy of these models, however, is hindered by their inability to capture indirect regulatory influences on other pathway genes. Here, we examine the manifestation of these indirect influences on transgenic transcript and protein abundances, identifying putative indirect regulatory influences that occur when one or more specific monolignol pathway genes are perturbed. We created a computational model using sparse maximum likelihood to estimate the resulting monolignol transcript and protein abundances in transgenic Populus trichocarpa based on targeted knockdowns of specific monolignol genes. Using in-silico simulations of this model and root mean square error, we showed that our model more accurately estimated transcript and protein abundances, in comparison to previous models, when individual and families of monolignol genes were perturbed. We leveraged insight from the inferred network structure obtained from our model to identify potential genes, including PtrHCT, PtrCAD, and Ptr4CL, involved in post-transcriptional and/or post-translational regulation. Our model provides a useful computational tool for exploring the cascaded impact of single and combinatorial modifications of monolignol specific genes on lignin and other wood properties. DA - 2020/4/10/ PY - 2020/4/10/ DO - 10.1371/journal.pcbi.1007197 UR - https://doi.org/10.1371/journal.pcbi.1007197 ER - TY - JOUR TI - Computer vision approach to characterize size and shape phenotypes of horticultural crops using high-throughput imagery AU - Haque, Samiul AU - Lobaton, Edgar AU - Nelson, Natalie AU - Yencho, G Craig AU - Pecota, Kenneth V AU - Mierop, Russell AU - Kudenov, Michael W AU - Boyette, Mike AU - Williams, Cranos M AB - Abstract For many horticultural crops, variation in quality (e.g., shape and size) contribute significantly to the crop’s market value. Metrics characterizing less subjective harvest quantities (e.g., yield and total biomass) are routinely monitored. In contrast, metrics quantifying more subjective crop quality characteristics such as ideal size and shape remain difficult to characterize objectively at the production-scale due to the lack of modular technologies for high-throughput sensing and computation. Several horticultural crops are sent to packing facilities after having been harvested, where they are sorted into boxes and containers using high-throughput scanners. These scanners capture images of each fruit or vegetable being sorted and packed, but the images are typically used solely for sorting purposes and promptly discarded. With further analysis, these images could offer unparalleled insight on how crop quality metrics vary at the industrial production-scale and provide further insight into how these characteristics translate to overall market value. At present, methods for extracting and quantifying quality characteristics of crops using images generated by existing industrial infrastructure have not been developed. Furthermore, prior studies that investigated horticultural crop quality metrics, specifically of size and shape, used a limited number of samples, did not incorporate deformed or non-marketable samples, and did not use images captured from high-throughput systems. In this work, using sweetpotato (SP) as a use case, we introduce a computer vision algorithm for quantifying shape and size characteristics in a high-throughput manner. This approach generates 3D model of SPs from two 2D images captured by an industrial sorter 90 degrees apart and extracts 3D shape features in a few hundred milliseconds. We applied the 3D reconstruction and feature extraction method to thousands of image samples to demonstrate how variations in shape features across sweetptoato cultivars can be quantified. We created a sweetpotato shape dataset containing sweetpotato images, extracted shape features, and qualitative shape types (U.S. No. 1 or Cull). We used this dataset to develop a neural network-based shape classifier that was able to predict Cull vs. U.S. No. 1 sweetpotato with 84.59% accuracy. In addition, using univariate Chi-squared tests and random forest, we identified the most important features for determining qualitative shape (U.S. No. 1 or Cull) of the sweetpotatoes. Our study serves as the first step towards enabling big data analytics for sweetpotato agriculture. The methodological framework is readily transferable to other horticultural crops, particularly those that are sorted using commercial imaging equipment. DA - 2020/7/26/ PY - 2020/7/26/ DO - 10.1101/2020.07.24.199539 VL - 7 UR - https://doi.org/10.1101/2020.07.24.199539 ER - TY - CONF TI - Preliminary Assessment of Human Biological Responses to Low-level Ozone AU - Latif, Tahmid AU - Gonzalez, Laura AU - Dieffenderfer, James AU - Liao, Yuwei AU - Hernandez, Michelle AU - Misra, Veena AU - Lobaton, Edgar AU - Bozkurt, Alper AB - Multi-modal wearable sensors monitoring physiology and environment simultaneously would offer a great promise to manage respiratory health, especially for asthmatic patients. In this study, we present a preliminary investigation of the correlation between ozone exposure, heart rate, heart rate variability, and lung function. As the first step, we tested the effect of low-level ozone exposure in a sample size of four healthy individuals. Test subjects underwent controlled exposure from 0.06 to 0.08 ppm of ozone and filtered air on two separate exposure days. Our results indicate an increment in mean heart rate in three out of four test subjects when exposed to ozone. We have also observed that changes in mean heart rate has a positive correlation with changes in lung function and a negative correlation with changes in neutrophil count. These results provide a baseline understanding of healthy subjects as a control group. C2 - 2020/10/25/ C3 - 2020 IEEE SENSORS DA - 2020/10/25/ DO - 10.1109/sensors47125.2020.9278620 PB - IEEE UR - http://dx.doi.org/10.1109/sensors47125.2020.9278620 ER - TY - CONF TI - Low-cost Smart Camera System for Water Stress Detection in Crops AU - Ramos-Giraldo, Paula AU - Reberg-Horton, S. Chris AU - Mirsky, Steven AU - Lobaton, Edgar AU - Locke, Anna M. AU - Henriquez, Esleyther AU - Zuniga, Ane AU - Minin, Artem AB - The availability of easy-to-use, low-cost, and highly scalable tools makes it possible to achieve rapid and widespread adoption of precision agriculture. In this paper we outline the development of a smart camera system to detect drought stress in corn and soybean crops. The system is comprised of a Raspberry Pi Zero W, Raspberry Pi Camera, WittyPi mini, a cooling and solar power system, temperature sensors both inside and outside of the box, and infrared canopy temperature and light sensors. The system was built to collect data in a configurable time frame and has an embedded machine-learning (ML) processing system. The camera was configured using an Internet of Things (IoT) platform to manage the device and send images to the Cloud. One of the challenges for this system was to effectively implement machine learning models on this limited-resource embedded platform. We achieved an accuracy of 74% with the embedded machine learning algorithm when classifying water stress in soybeans. C2 - 2020/10/25/ C3 - 2020 IEEE SENSORS DA - 2020/10/25/ DO - 10.1109/sensors47125.2020.9278744 PB - IEEE UR - http://dx.doi.org/10.1109/sensors47125.2020.9278744 ER - TY - CONF TI - Feasibility Study of Water Stress Detection in Plants using a High-Throughput Low-Cost System AU - Silva, Rafael L. AU - Starliper, Nathan AU - Bhosale, Dinesh Kiran AU - Taggart, Matthew AU - Ranganath, Rakshita AU - Sarje, Trupti AU - Daniele, Michael AU - Bozkurt, Alper AU - Rufty, Thomas AU - Lobaton, Edgar AB - The importance of efficient water management for crops and its impact on canopy development is undeniable, where high-throughput systems connected to the cloud have a great potential to aggregate measurements for a cyber-physical analysis. In this work, we develop a vision based high-throughput system to aid the identification and early detection of stress caused by water deficit in maize plants. We show that image processing techniques combined with a near infrared camera allow the distinction between a well watered maize plant and one that has its water supply neglected. Our preliminary results demonstrate the potential viability of applying predictive models for early water stress detection. C2 - 2020/10/25/ C3 - 2020 IEEE SENSORS DA - 2020/10/25/ DO - 10.1109/sensors47125.2020.9278711 PB - IEEE UR - http://dx.doi.org/10.1109/sensors47125.2020.9278711 ER - TY - JOUR TI - An integrated UGV-UAV system for construction site data collection AU - Asadi, Khashayar AU - Suresh, Akshay Kalkunte AU - Ender, Alper AU - Gotad, Siddhesh AU - Maniyar, Suraj AU - Anand, Smit AU - Noghabaei, Mojtaba AU - Han, Kevin AU - Lobaton, Edgar AU - Wu, Tianfu T2 - Automation in Construction AB - There have been recent efforts to increase the degree of automation and frequency of data collection for construction applications using Unmanned Aerial/Ground Vehicles (UAV/UGV). However, the current practice of data collection is traditionally performed, which is manual, costly, time-consuming, and error-prone. Developing vision-based mobile robotic systems that are aware of its surrounding and capable of autonomous navigation are becoming essential to many construction applications, namely surveying, monitoring, and inspection. Nevertheless, the systems above suffer from a series of performance issues. One major problem is inefficient navigation in indoor and cluttered scenes with many obstacles and barriers, where some places are inaccessible by a UGV. To provide a solution to this problem, this paper designs a UAV-UGV team that integrates two custom-built mobile robots. The UGV autonomously navigates through space, leveraging its sensors. The UAV acts as an external eye for the UGV, observing the scene from a vantage point that is inaccessible to the UGV. The relative pose of the UAV is estimated continuously, which allows it to maintain a fixed location that is relative to the UGV. The key aspects for the development of this system that is capable of autonomous navigation are the localization of both UAV and UGV, mapping of the surrounding environment, and efficient path planning using multiple sensors. The proposed system is tested in an indoor and cluttered construction-like environment. The performance of the system demonstrates the feasibility of developing and deploying a robust and automated data collection system for construction applications in the near future. DA - 2020/4// PY - 2020/4// DO - 10.1016/j.autcon.2019.103068 VL - 112 SP - 103068 UR - http://dx.doi.org/10.1016/j.autcon.2019.103068 ER - TY - JOUR TI - A Smart Autonomous WPT System for Electric Wheelchair Applications With Free-Positioning Charging Feature AU - Azad, Ahmed AU - Tavakoli, Reza AU - Pratik, Ujjwal AU - Varghese, Benny AU - Coopmans, Calvin AU - Pantic, Zeljko T2 - IEEE Journal of Emerging and Selected Topics in Power Electronics AB - Electric wheelchairs (EWs) are gradually replacing conventional wheelchairs as an assistive tool for people with disabilities who are unable to use the physical force to drive manual wheelchairs on their own. EW charging requires manipulating, plugging in, and unplugging an off-board charger, which can be challenging or impossible for people with severe disabilities. In this paper, a comprehensive solution to the problem of EW recharging is provided in the form of a smart, autonomous charging system, based on the wireless power transfer (WPT) technology. In this paper, a sufficiently large area of 0.75 m 2 for a floor-charging pad involving multiple primary coils has been implemented while offering a free-positioning charging feature. A novel design methodology for primary and secondary charging pads' optimization has been developed, taking into account various complex real-life constraints. In addition, a novel 250-W WPT controller design has been employed to maximize misalignment tolerance up to 7 cm while maintaining high system efficiency. In this paper, a novel, comprehensive, system-level organization of a master controller design has been presented which manages continuous coordination between the WPT controllers and the autonomous docking controller, records important system data, maintains safe operation of overall system, and prevents hazardous exposure to potentially harmful magnetic field beyond 15 μT. In addition, a novel design methodology for primary and secondary charging pads' optimization has been developed, which takes into account various real-life constraints, and provides a fair comparison between different designs in a multivariable environment. The proposed design is tested in laboratory conditions and later validated in a practical environment. DA - 2020/12// PY - 2020/12// DO - 10.1109/JESTPE.2018.2884887 SP - 1-1 UR - https://doi.org/10.1109/JESTPE.2018.2884887 KW - Assistive autonomy KW - dynamic contactless battery charging KW - electric wheelchair (EW) KW - free-positioning KW - ground robotics KW - stationary charging KW - wireless power transfer (WPT) ER - TY - CONF TI - A Methodology for Seamless Hot-Swap of Converters in DC Microgrids AU - Sharma, Shrivatsal AU - Iyer, Vishnu Mahadeva AU - Bhattacharya, Subhashish AU - Kikuchi, Jun AU - Zou, Ke AU - Gupta, Mahima T2 - IEEE C2 - 2020/// C3 - IECON 2020 The 46th Annual Conference of the IEEE Industrial Electronics Society DA - 2020/// SP - 3143-3150 ER - TY - CONF TI - An Active Damping Control Strategy for a Multi-Cell AC-DC Solid State Transformer AU - Iyer, Vishnu Mahadeva AU - Gulur, Srinivas AU - Bhattacharya, Subhashish T2 - IEEE C2 - 2020/// C3 - 2020 IEEE Energy Conversion Congress and Exposition (ECCE) DA - 2020/// SP - 4842-4848 ER - TY - THES TI - An Approach Towards Extreme Fast Charging Station Architecture for Electric Vehicles with Partial Power Processing AU - Iyer, Vishnu Mahadeva DA - 2020/// PY - 2020/// PB - North Carolina State University ER - TY - CONF TI - A Control Method of Hybrid Transformer enabled Harmonic Isolator for Sensitive Clustered Harmonic Loads AU - Prabowo, Yos AU - Iyer, Vishnu Mahadeva AU - Bhattacharya, Subhashish AU - Aeloiza, Eddy T2 - IEEE C2 - 2020/// C3 - 2020 IEEE Energy Conversion Congress and Exposition (ECCE) DA - 2020/// SP - 4872-4878 ER - TY - CONF TI - A Methodology to Select the Number of Cascaded Cells for a Medium Voltage Multilevel AC-DC Solid State Transformer AU - Iyer, Vishnu Mahadeva AU - Sharma, Shrivatsal AU - Bhattacharya, Subhashish T2 - IEEE C2 - 2020/// C3 - 2020 IEEE Transportation Electrification Conference & Expo (ITEC) DA - 2020/// SP - 55-61 ER - TY - CONF TI - System Level Power Analysis with UPM AU - Baker, A. AU - Davis, W.R. AU - Dhanwada, N. AU - Frenkil, J. AU - Ratchkov, D. T2 - Design Automation Conference (DAC) C2 - 2020/7/20/ DA - 2020/7/20/ PY - 2020/7/20/ ER - TY - SOUND TI - A Gentle Introduction to the Open Model Interface for Reliability Simulations AU - Davis, W.R. DA - 2020/4/24/ PY - 2020/4/24/ ER - TY - SOUND TI - An Industry-standard approach toward modeling device aging AU - Davis, W.R. AU - Shaw, C. DA - 2020/4/28/ PY - 2020/4/28/ M3 - Virtual session video ER - TY - CONF TI - EDA Roadmap for Machine Learning & AI Standardization AU - Davis, W.R. T2 - DesignCon C2 - 2020/1/30/ CY - Santa Clara, CA DA - 2020/1/30/ PY - 2020/1/30/ ER - TY - CONF TI - How to write a compact reliability model with the Open Model Interface (OMI AU - Davis, W.R. AU - Shaw, C. AU - Hassan, A.Ramadan T2 - 2020 IEEE International Reliability Physics Symposium (IRPS) AB - As device structures and process technologies become more complex, they become more expensive to implement. It is therefore essential for profitability to have good yield. Part of achieving this yield is testing for reliability, which is further complicated by new materials being used [1] , [2] . Some EDA vendors have incorporated this need in specific areas but each has a separate solution and nothing in common, leaving the designer with a bewildering choice of different coding-styles to use when testing the reliability on his or her circuit. Semiconductor foundries became aware of this need, and one of them (TSMC [3] ) came up with an approach to modify model parameters through an interface to the simulator called the TSMC Model Interface (TMI). This interface was licensed to the Compact Model Coalition (CMC) [4] , which expanded and extended it, releasing it as Open Model Interface (OMI) to be used as a common platform for all foundries and model developers. C2 - 2020/5/30/ C3 - 2020 IEEE International Reliability Physics Symposium (IRPS) CY - Dallas, TX DA - 2020/5/30/ PY - 2020/4/28/ DO - 10.1109/IRPS45951.2020.9128222 ER - TY - JOUR TI - A Novel Order Reduced Synchronous Power Control for Grid-Forming Inverters AU - Quan, Xiangjun AU - Huang, Alex Q. AU - Yu, Hui T2 - IEEE Transactions on Industrial Electronics AB - Nowadays, the grid-forming inverter, also referred as the voltage-controlled inverter, has gained greater attention due to its advantages in providing power support to the grid. The power control is central to grid-forming inverters in realizing grid-support functionalities, such as the droop control or virtual inertia emulation. However, in these controls, the dynamic response of the instantaneous power usually suffers from overshoots and oscillations. To improve the dynamic response of the injected instantaneous power, this letter introduces a novel synchronous active power control for the voltage-controlled grid-connected inverter. The droop coefficient can be released from adjusting the damping factor of the system. A novel design method is proposed to reduce the second-order power loop to a first-order model. Consequently, the droop and reference-following controls operate like a first-order system with an excellent dynamic response. Moreover, the virtual inertia can be designed freely without affecting the performance of the power control. The correctness of the control is verified experimentally. DA - 2020/12// PY - 2020/12// DO - 10.1109/TIE.2019.2959485 VL - 67 IS - 12 SP - 10989-10995 UR - https://doi.org/10.1109/TIE.2019.2959485 KW - Power control KW - Inverters KW - Voltage control KW - Power system stability KW - Frequency control KW - Power system dynamics KW - Emulation KW - Droop KW - synchronous power control (SPC) KW - virtual inertia (VI) emulation KW - voltage-controlled inverter ER - TY - JOUR TI - Accurate Consensus-based Distributed Averaging with Variable Time Delay in Support of Distributed Secondary Control Algorithms AU - Du, Yuhua AU - Tu, Hao AU - Yu, Hui AU - Lukic, Srdjan T2 - IEEE Transactions on Smart Grid AB - Distributed secondary control has been widely used in hierarchical control structures, where multiple distributed generators (DGs) need to coordinate to regulate system voltage and frequency. In these systems, consensus algorithms determine the average of a group of dynamic states (e.g., voltages measured by a group of DGs). To be useful, consensus algorithms must be computationally efficient, stable and accurate. In practice, numerous practical implementation challenges significantly affect the consensus equilibrium. In this paper, we quantify the accuracy deviations of the distributed average observer algorithms proposed in the literature to demonstrate the problems with the state-of-the-art distributed averaging techniques. A novel approach is proposed that achieves accurate average tracking in the presence of time-varying communication delays among agents. In our implementation, time synchronization of all distributed controllers is enabled by a novel software platform, called Resilient Information Architecture Platform for the Smart Grid (RIAPS). The proposed distributed average observer is implemented on hardware controllers and its effectiveness is validated in a controller hardware-in-the-loop testbed. DA - 2020/// PY - 2020/// DO - 10.1109/tsg.2020.2975752 VL - 11 IS - 4 SP - 2918-2928 UR - http://dx.doi.org/10.1109/tsg.2020.2975752 KW - Heuristic algorithms KW - Delays KW - Observers KW - Voltage control KW - Communication networks KW - Synchronization KW - Convergence KW - Distributed control KW - dynamic consensus KW - time-varying delay KW - ratio consensus KW - secondary control ER - TY - JOUR TI - Selective Harmonic Current Rejection for Virtual Oscillator Controlled Grid-Forming Voltage Source Converters AU - Awal, M A AU - Yu, Hui AU - Husain, Iqbal AU - Yu, Wensong AU - Lukic, Srdjan M. T2 - IEEE Transactions on Power Electronics AB - Virtual oscillator control (VOC) is a nonlinear grid-forming controller that simultaneously achieves the functionality of output voltage control and primary control layers in a power electronics interfaced distributed generation (DG) unit. Unlike conventional phasor-based primary control methods such as the droop control and virtual synchronous machine control, VOC is a time-domain controller that can guarantee almost global asymptotic synchronization. However, the high-frequency dynamics has largely been ignored in the analysis of VOC in prior art; as a result, VOC-based DGs fail to suppress harmonic current in the presence of harmonic distortion in the network-side voltage. In this work, we demonstrate that frequency-domain method can be used for oscillator-based converters in the high-frequency range, specifically, for harmonic mitigation in the converter output current. We propose a virtual impedance-based selective harmonic current suppression method, and demonstrate that it is better to use the network-side current feedback rather than that of the converter-side current for VOC implementation with virtual impedance control. Established harmonic rejection strategies for grid-following and conventional grid-forming converters are compared with the proposed method for VOC. Through impedance-based analysis, we demonstrate that the proposed method augments the passivity range of the converter terminal response with a much simpler implementation. The proposed harmonic suppression strategy is validated through hardware experiments using a single-phase inverter prototype. DA - 2020/8// PY - 2020/8// DO - 10.1109/tpel.2020.2965880 VL - 35 IS - 8 SP - 8805-8818 J2 - IEEE Trans. Power Electron. OP - SN - 0885-8993 1941-0107 UR - http://dx.doi.org/10.1109/tpel.2020.2965880 DB - Crossref KW - Grid-forming converter KW - harmonic current suppression KW - impedance shaping KW - virtual oscillator control (VOC) ER - TY - JOUR TI - Resilient Information Architecture Platform for the Smart Grid: A Novel Open-Source Platform for Microgrid Control AU - Tu, Hao AU - Du, Yuhua AU - Yu, Hui AU - Dubey, Abhishek AU - Lukic, Srdjan AU - Karsai, Gabor T2 - IEEE Transactions on Industrial Electronics AB - Microgrids are seen as an effective way to achieve reliable, resilient, and efficient operation of the power distribution system. Core functions of the microgrid control system are defined by the IEEE Standard 2030.7; however, the algorithms that realize these functions are not standardized, and are a topic of research. Furthermore, the corresponding controller hardware, operating system, and communication system to implement these functions vary significantly from one implementation to the next. In this article, we introduce an open-source platform, resilient information architecture platform for the smart grid (RIAPS), ideally suited for implementing and deploying distributed microgrid control algorithms. RIAPS provides a design-time tool suite for development and deployment of distributed microgrid control algorithms. With support from a number of run-time platform services, developed algorithms can be easily implemented and deployed into real microgrids. To demonstrate the unique features of RIAPS, we propose and implement a distributed microgrid secondary control algorithm capable of synchronized and proportional compensation of voltage unbalance using distributed generators. Test results show the effectiveness of the proposed control and the salient features of the RIAPS platform. DA - 2020/11// PY - 2020/11// DO - 10.1109/TIE.2019.2952803 VL - 67 IS - 11 SP - 9393-9404 UR - https://doi.org/10.1109/TIE.2019.2952803 KW - Microgrids KW - Hardware KW - Synchronization KW - Control systems KW - Real-time systems KW - Protocols KW - Open source software KW - Distributed control KW - microgrid KW - microgrid control system ER - TY - JOUR TI - Reputation-based Collaborative Distributed Energy Management System Framework for Cyber-physical Microgrids: Resilience against Profit-driven Attacks AU - Cheng, Zheyuan AU - Chow, Mo-Yuen T2 - 2020 IEEE Power & Energy Society Innovative Smart Grid Technologies Conference (ISGT) AB - This article investigates the resilience of the consensus-based distributed microgrid energy management system (MG-EMS) against profit-driven attacks. A holistic framework, called reputation-based collaborative distributed EMS (R-CoDEMS), is proposed to model the system dynamics, profit-driven adversaries, and the cybersecurity of the distributed MG-EMS under profit-driven attacks. Simulation results on a real microgrid system indicate that the R-CoDEMS can effectively detect, mitigate, and recover from the attacks in a fully distributed fashion. The main technical contributions of this research work are: (1) systematically formulating and quantifying the system adversary, assets, threats, vulnerabilities, and risks of the consensus-based distributed MG-EMS; (2) proposing a reputation-based attack detection and mitigation strategy to overcome single and coordinated profit-driven attacks. DA - 2020/2// PY - 2020/2// DO - 10.1109/isgt45199.2020.9087737 ER - TY - JOUR TI - An Augmented Bayesian Reputation Metric for Trustworthiness Evaluation in Consensus-based Distributed Microgrid Energy Management Systems with Energy Storage AU - Cheng, Zheyuan AU - Chow, Mo-Yuen T2 - 2020 2nd IEEE International Conference on Industrial Electronics for Sustainable Energy Systems (IESES) AB - Consensus-based distributed microgrid energy management system is one of the most used distributed control strategies in the microgrid area. To improve its cybersecurity, the system needs to evaluate the trustworthiness of the participating agents in addition to the conventional cryptography efforts. This paper proposes a novel augmented reputation metric to evaluate the agents' trustworthiness in a distributed fashion. The proposed metric adopts a novel augmentation method to substantially improve the trust evaluation and attack detection performance under three typical difficult-to-detect attack patterns. The proposed metric is implemented and validated on a real-time HIL microgrid testbed. DA - 2020/9// PY - 2020/9// DO - 10.1109/ieses45645.2020.9210638 ER - TY - JOUR TI - A Random-Weighted Privacy-Preserving Distributed Algorithm for Energy Management in Microgrid with Energy Storage Devices AU - Ye, Feng AU - Cheng, Zheyuan AU - Cao, Xianghui AU - Chow, Mo-Yuen T2 - 2020 2nd IEEE International Conference on Industrial Electronics for Sustainable Energy Systems (IESES) AB - In collaborative distributed energy management system (CoDEMS) with distributed energy storage devices (DESDs), privacy is getting more and more attention, because customer and grid may suffer losses due to unintentional privacy disclosure. In this paper, we firstly introduce the networked model, distributed energy management problem and consensus-based CoDEMS algorithm. Then, we analyze the disclosure of true power supply and demand with adding-noise privacy-preserving consensus-based distributed (APCD) algorithm. To preserve the privacy, we proposed the random-weighted privacy-preserving consensus-based collaborative distributed energy management system (RP-CoDEMS) algorithm to preserve the confidentiality of the neighborhood communication. The effectiveness of RP-CoDEMS algorithm is demonstrated by simulation. DA - 2020/9// PY - 2020/9// DO - 10.1109/ieses45645.2020.9210675 ER - TY - JOUR TI - A Novel Most Significant Cell Methodology in a Battery Pack with Serial Cell Connection AU - Huang, Cong-Sheng AU - Cheng, Zheyuan AU - Balagopal, Bharat AU - Chow, Mo-Yuen T2 - 2020 2nd IEEE International Conference on Industrial Electronics for Sustainable Energy Systems (IESES) AB - Rechargeable lithium-ion batteries are now widely adopted in our life. To fulfil various energy and power requirements in real-world applications, battery cells are connected to form battery packs. The cell-to-cell difference exists in the battery pack after manufactured, and this difference will further deteriorates when the battery cells are exposed and used in various operating conditions. This unavoidable cell-to-cell difference results in early cut-off on the battery pack, which influences the performance of the battery pack and makes accurately estimating the battery pack SOC challenging. This paper proposes a novel real-time algorithm to effectively identify the most significant cells in a serial-connected battery pack in order to accurately estimate the SOC of the battery pack. A battery pack composed of ten serial-connected battery cells is carried out in this paper to evaluate the performance of the proposed algorithm. The results show that the most significant cells are successfully identified, and the SOC of the battery pack is estimated accurately based on the identified most significant cell. DA - 2020/9// PY - 2020/9// DO - 10.1109/ieses45645.2020.9210686 ER - TY - JOUR TI - Skin-interfaced soft microfluidic systems with modular and reusable electronics for: In situ capacitive sensing of sweat loss, rate and conductivity AU - Hourlier-Fargette, A. AU - Schon, S. AU - Xue, Y. AU - Avila, R. AU - Li, W. AU - Gao, Y. AU - Liu, C. AU - Kim, S.B. AU - Raj, M.S. AU - Fields, K.B. AU - Parsons, B.V. AU - Lee, K. AU - Lee, J.Y. AU - Chung, H.U. AU - Lee, S.P. AU - Johnson, M. AU - Bandodkar, A.J. AU - Gutruf, P. AU - Model, J.B. AU - Aranyosi, A.J. AU - Choi, J. AU - Ray, T.R. AU - Ghaffari, R. AU - Huang, Y. AU - Rogers, J.A. T2 - Lab on a Chip AB - Important insights into human health can be obtained through the non-invasive collection and detailed analysis of sweat, a biofluid that contains a wide range of essential biomarkers. Skin-interfaced microfluidic platforms, characterized by soft materials and thin geometries, offer a collection of capabilities for in situ capture, storage, and analysis of sweat and its constituents. In ambulatory uses cases, the ability to provide real-time feedback on sweat loss, rate and content, without visual inspection of the device, can be important. This paper introduces a low-profile skin-interfaced system that couples disposable microfluidic sampling devices with reusable 'stick-on' electrodes and wireless readout electronics that remain isolated from the sweat. An ultra-thin capping layer on the microfluidic platform permits high-sensitivity, contactless capacitive measurements of both sweat loss and sweat conductivity. This architecture avoids the potential for corrosion of the sensing components and eliminates the need for cleaning/sterilizing the electronics, thereby resulting in a cost-effective platform that is simple to use. Optimized electrode designs follow from a combination of extensive benchtop testing, analytical calculations and FEA simulations for two sensing configurations: (1) sweat rate and loss, and (2) sweat conductivity, which contains information about electrolyte content. Both configurations couple to a flexible, wireless electronics platform that digitizes and transmits information to Bluetooth-enabled devices. On-body field testing during physical exercise validates the performance of the system in scenarios of practical relevance to human health and performance. DA - 2020/// PY - 2020/// DO - 10.1039/d0lc00705f VL - 20 IS - 23 SP - 4391-4403 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85096888147&partnerID=MN8TOARS ER - TY - JOUR TI - Recent advances in neurotechnologies with broad potential for neuroscience research AU - Vázquez-Guardado, Abraham AU - Yang, Yiyuan AU - Bandodkar, Amay J. AU - Rogers, John A. T2 - Nature Neuroscience DA - 2020/// PY - 2020/// DO - 10.1038/s41593-020-00739-8 VL - 23 IS - 12 SP - 1522-1536 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85096055262&partnerID=MN8TOARS ER - TY - JOUR TI - Linear CE and 1-bit Quantized Precoding With Optimized Dithering AU - Saxena, Amodh Kant AU - Mezghani, Amine AU - Heath, Robert W. T2 - IEEE OPEN JOURNAL OF SIGNAL PROCESSING AB - High power amplifiers (HPA), used at transmission, add nonlinear impairments to the output signals. Through Constant envelope (CE) transmission, distortion in the signal can be avoided without wasting power on PA linearization. A more restricted form of CE transmission, 1-bit quantized transmission, further simplifies the RF chain and reduces the DAC power consumption. In this paper, for CE transmission and 1-bit quantized transmission at the BS antennas, we analyze downlink transmission for low complexity linear precoding. We observe that for small numbers of users in the downlink, correlation among the quantization error components across BS antennas is high, deteriorating the performance rapidly as number of users become smaller. To improve performance for smaller numbers of downlink users, we propose the addition of correlated Gaussian dither to the precoded signal before quantization and subsequent transmission. We observe that the receive SQINR peaks for finite non-trivial dither power. For given value of transmit power, number of BS antennas and number of users, SQINR is maximized analytically by the transmitter, to find the optimum dither power, using the Bussgang decomposition. We observe that with the implementation of optimized dithering, the error floor in the coded BER at high transmit power, for CE and 1-bit quantized transmissions, is pushed down significantly. We also observe that optimum dither power increases monotonically with transmit power, with rate of increase decreasing with increasing transmit power. Further, the optimum dither power strictly increases with number of BS antennas. DA - 2020/// PY - 2020/// DO - 10.1109/OJSP.2020.3040590 VL - 1 SP - 310-325 SN - 2644-1322 KW - 1-bit quantized transmission KW - massive MIMO KW - downlink precoding KW - constant envelope transmission KW - 1-bit DACs KW - Bussgang decomposition ER - TY - CONF TI - AERPAW Emulation Overview AU - Sichitiu, M.L. AU - Guvenc, I. AU - Dutta, R. AU - Marojevic, V. AU - Floyd, B. AB - The Aerial Experimentation and Research Platform for Advanced Wireless (AERPAW) has been recently funded by the National Science Foundation (NSF)'s Platforms for Advanced Wireless Research (PAWR) program. The AERPAW platform will enable experiments with programmable radios and programmable unmanned aerial vehicles (UAVs), conducted in a safe and repeatable manner. Several architectural components are crucial for enabling the envisioned capabilities of the testbed. In this paper, after providing a high level overview of AERPAW, we first present the emulation design of AERPAW vehicles. Subsequently, we describe various different options for wireless channel emulation in AERPAW. We start with a generalized model for wireless emulation, and expand that model to packet-level emulation, I-Q level emulation, and radio-frequency (RF)-level emulation. A discussion on the trade-offs among these various different emulation possibilities is also provided. C2 - 2020/// C3 - WiNTECH 2020 - Proceedings of the 14th ACM Workshop on Wireless Network Testbeds, Experimental evaluation and CHaracterization, Part of ACM MobiCom 2020 DA - 2020/// DO - 10.1145/3411276.3412188 SP - 1-8 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85093361697&partnerID=MN8TOARS ER - TY - CONF TI - Welcome Message from Chairs AU - Khalil, W. AU - Floyd, B. AU - Shana’a, O. C2 - 2020/// C3 - Digest of Papers - IEEE Radio Frequency Integrated Circuits Symposium DA - 2020/// DO - 10.1109/RFIC49505.2020.9218358 VL - 2020-August SP - i-ii UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85093967309&partnerID=MN8TOARS ER - TY - JOUR TI - Mixer-First MIMO Receiver with Reconfigurable Multi-Port Decoupling and Matching AU - Wilson, C. AU - Dean, J. AU - Floyd, B.A. T2 - IEEE Journal of Solid-State Circuits AB - This article presents architectures to realize mutual impedance tuning for N-path mixer-first multiple-input multiple-output (MIMO) receivers. A coupled response at baseband is upconverted to radio frequency to realize the tunable mutual impedance. This enables the dynamic decoupling of coupled-antenna systems. The impedance of a multi-port receiver is analyzed and shown to be able to provide a wideband tunable and broadband coupled response with an array of RC baseband networks. A two-port mixer-first MIMO receiver is realized in a 45-nm silicon on insulator (SOI) CMOS and includes polyphase baseband resistive-coupling networks. The two receivers consume 16 mW and operate over 0.1-3 GHz. Each receiver achieves 3-6-dB noise figure and 14-40-dB conversion gain. The MIMO system with N-path decoupling was measured with two cases: two monopole antennas and a two-port single-aperture antenna. Signal-to-noise ratio was increased by 7 and 5.2 dB, respectively. DA - 2020/// PY - 2020/// DO - 10.1109/JSSC.2020.2967552 VL - 55 IS - 5 SP - 1401-1410 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85083916933&partnerID=MN8TOARS KW - Decoupling KW - multiple-input multiple-output (MIMO) KW - mixer-first KW - N-phase KW - passive mixer KW - polyphase KW - receiver ER - TY - JOUR TI - An Energy-Synchronous Direct Antenna Modulation Method for Phase Shift Keying AU - Schab, Kurt AU - Huang, Danyang AU - Adams, Jacob J. T2 - IEEE OPEN JOURNAL OF ANTENNAS AND PROPAGATION AB - A novel scheme for transmitting broadband phase shift keyed signals from electrically small antennas using energy-synchronous direct antenna modulation is described. We outline fundamental operating principles of the method and experimentally compare its performance to that of a conventional band-limited transmit antenna with the same electrical size and radiation efficiency. Transmitted waveforms are analyzed in the time domain both at RF and baseband. Results show significant increases in signal quality, suggesting a larger effective transmit bandwidth and greater potential throughput when the proposed direct antenna modulation scheme is used. DA - 2020/// PY - 2020/// DO - 10.1109/OJAP.2020.2972842 VL - 1 SP - 41-46 SN - 2637-6431 KW - Electrically small antennas KW - direct modulation KW - antenna measurements KW - phase shift keying KW - time-varying circuits ER - TY - JOUR TI - Unsupervised ResNet-Inspired Beamforming Design Using Deep Unfolding Technique AU - Lin, Chia-Hung AU - Lee, Yen-Ting AU - Chung, Wei-Ho AU - Lin, Shih-Chun AU - Lee, Ta-Sung T2 - 2020 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM) AB - Beamforming is a key technology in communication systems of the fifth generation and beyond. However, traditional optimization-based algorithms are often computationally prohibited from performing in a real-time manner. On the other hand, the performance of existing deep learning (DL)-based algorithms can be further improved. As an alternative, we propose an unsupervised ResNet-inspired beamforming (RI-BF) algorithm in this paper that inherits the advantages of both pure optimization-based and DL-based beamforming for efficiency. In particular, a deep unfolding technique is introduced to reference the optimization process of the gradient ascent beamforming algorithm for the design of our neural network (NN) architecture. Moreover, the proposed RI-BF has three features. First, unlike the existing DL-based beamforming method, which employs a regularization term for the loss function or an output scaling mechanism to satisfy system power constraints, a novel NN architecture is introduced in RI-BF to generate initial beamforming with a promising performance. Second, inspired by the success of residual neural network (ResNet)-based DL models, a deep unfolding module is constructed to mimic the residual block of the ResNet-based model, further improving the performance of RI-BF based on the initial beamforming. Third, the entire RI-BF is trained in an unsupervised manner; as a result, labelling efforts are unnecessary. The simulation results demonstrate that the performance and computational complexity of our RI-BF improves significantly compared to the existing DL-based and optimization-based algorithms. DA - 2020/// PY - 2020/// DO - 10.1109/GLOBECOM42002.2020.9322638 SP - SN - 2576-6813 KW - MIMO KW - beamforming KW - transceiver design KW - deep learning KW - unsupervised learning KW - neural network KW - deep unfold ER - TY - JOUR TI - User Preference Learning-Aided Collaborative Edge Caching for Small Cell Networks AU - Pervej, Md Ferdous AU - Tan, Le Thanh AU - Hu, Rose Qingyang T2 - 2020 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM) AB - While next-generation wireless networks intend leveraging edge caching for enhanced spectral efficiency, quality of service, end-to-end latency, content sharing cost, etc., several aspects of it are yet to be addressed to make it a reality. One of the fundamental mysteries in a cache-enabled network is predicting what content to cache and where to cache so that high caching content availability is accomplished. For simplicity, most of the legacy systems utilize a static estimation - based on Zipf distribution, which, in reality, may not be adequate to capture the dynamic behaviors of the contents popularities. Forecasting user's preferences can proactively allocate caching resources and cache the needed contents, which is especially important in a dynamic environment with real-time service needs. Motivated by this, we propose a long short-term memory (LSTM) based sequential model that is capable of capturing the temporal dynamics of the users' preferences for the available contents in the content library. Besides, for a more efficient edge caching solution, different nodes in proximity can collaborate to help each other. Based on the forecast, a non-convex optimization problem is formulated to minimize content sharing costs among these nodes. Moreover, a greedy algorithm is used to achieve a sub-optimal solution. Using extensive simulation and analysis, we validate that the proposed algorithm performs better than other existing schemes. DA - 2020/// PY - 2020/// DO - 10.1109/GLOBECOM42002.2020.9322208 SP - SN - 2576-6813 KW - Content delivery network KW - edge caching KW - long short-term memory KW - small cell networks ER - TY - JOUR TI - Energy-Efficient Beamforming and Power Control for Uplink NOMA in mmWave UAV Networks AU - Rahmati, Ali AU - Hosseinalipour, Seyyedali AU - Yapici, Yavuz AU - Guvenc, Ismail AU - Dai, Huaiyu AU - Bhuyan, Arupjyoti T2 - 2020 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM) AB - The integration of unmanned aerial vehicles (UAVs) into the terrestrial communications networks with a variety of tasks is viewed as a key technology for 5G and beyond. In this work, we consider the uplink millimeter-wave (mmWave) transmission between a set of UAVs and a base station (BS), where the UAVs deploy uplink non-orthogonal multiple access (NOMA) in multiple clusters. Furthermore, the BS also serves its own desired ground user equipment (UE) in the presence of many other ground UEs associated with other cells, which share the same frequency band. Considering the limited energy budget of UAVs, we formulate an energy efficiency (EE) problem, and propose a solution aided by the Dinkelbach's algorithm and successive convex approximation (SCA). Using realistic air-to-ground (A2G) and terrestrial channel models, we assess the performance of the proposed algorithm under various circumstances (maximum transmit power for UAVs, quality-of-service (QoS) constraint for the desired UE, etc.), and identify the best use cases. DA - 2020/// PY - 2020/// DO - 10.1109/GLOBECOM42002.2020.9348114 SP - SN - 2576-6813 ER - TY - JOUR TI - Joint Power and Deployment Optimization for Multi-UAV Remote Edge Computing AU - He, Xiaofan AU - Jin, Richeng AU - Dai, Huaiyu T2 - 2020 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM) AB - Driven by the dramatic growth in computing capability and the inherent mobility of the unmanned aerial vehicles (UAVs), the recently advocated UAV edge computing paradigm is expected to enhance the coverage and the on-demand deployment capability of existing terrestrial edge computing systems. Nonetheless, due to the limited onboard resource of the UAV, single- UAV edge computing systems may still be incompetent when serving remote users. Although using multiple UAVs to form a traditional relay network is a viable solution to remote edge computing, it fails to exploit the computing capability of the UAVs. This entails a pressing need to develop multi-UAV remote edge computing mechanisms that allow the UAVs to handle part of the computation tasks using their local processors while conducting multi-hop computation task offloading. To achieve the best performance in such cases, the UAVs have to properly split their power budget for communication and computation and also move to suitable service locations. Nonetheless, finding the optimal UAV power allocation and deployment turns out to be an intractable high-dimensional monotonic optimization problem, even for a mild number of UAVs. To overcome this challenge, a more efficient algorithm that has a complexity only linear in the number of UAVs is developed by exploiting the special structure of this problem. In addition to analysis, numerical results are provided to validate the effectiveness of the proposed scheme. DA - 2020/// PY - 2020/// DO - 10.1109/GLOBECOM42002.2020.9348243 SP - SN - 2576-6813 ER - TY - JOUR TI - Differential Privacy and Prediction Uncertainty of Gossip Protocols in General Networks AU - Huang, Yufan AU - Jin, Richeng AU - Dai, Huaiyu T2 - 2020 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM) AB - Recent advances in social media and information technology have enabled much faster dissemination of information, while at the same time raise concerns about privacy leakage after various privacy breaches. Therefore, the privacy guarantees of information dissemination protocols have attracted increasing research interests, among which the gossip protocols assume vital importance in various information exchange applications. Very recently, the rigorous framework of differential privacy has been introduced to measure the privacy guarantees of gossip protocols in the simplified complete network scenario. In this work, we extend the study to general networks. First, lower bounds of the differential privacy guarantees are derived for the gossip protocols in general networks in both synchronous and asynchronous settings. The prediction uncertainty of the source node given a uniform prior is also determined. It is found that source anonymity is closely related to some key network structure parameters in the general network setting. Then, we investigate information spreading in wireless networks with unreliable communications, and quantity the tradeoff between differential privacy guarantees and information spreading efficiency. Finally, considering that the attacker may not be present in the beginning of the information dissemination process, the scenario of delayed monitoring is studied and the corresponding differential privacy guarantees are evaluated. DA - 2020/// PY - 2020/// DO - 10.1109/GLOBECOM42002.2020.9322558 SP - SN - 2576-6813 ER - TY - CONF TI - Design and Performance Assessment of a Locally Developed Solar Pipe Light AU - Rahman, Mohammad Mahinur AU - Khan, Md. Ziaur Rahman T2 - 2020 11th International Conference on Electrical and Computer Engineering (ICECE) AB - In recent times, there has been an increased demand for alternative energy sources in place of conventional sources for improved environmental conditions, and sustainable way of living. Utilization of daylight for illumination of building interior in place of electricity is a viable means of energy saving. A simple, cost-effective product for daylight exploitation is a solar pipe light. In this context, the design of a solar pipe light is proposed which can redirect natural light without bringing in glare or excessive heat. The design has been constructed and tested in a laboratory. The constructed sample has been implemented at the RIMSO Foundation Battery Manufacturing Factory and its performance has been evaluated at different weather conditions based on Daylight Factor (DF), minimum Daylight Autonomy (DAm), and Useful Daylight Illuminance (UDI). A desirable DF at both laboratory tests and field tests proves the usefulness of the solar pipe light. Considering the results, solar pipe light has great potential to serve the needs for sustainable alternative lighting in the context of Bangladesh. C2 - 2020/12/17/ C3 - 2020 11th International Conference on Electrical and Computer Engineering (ICECE) DA - 2020/12/17/ DO - 10.1109/icece51571.2020.9393057 PB - IEEE SN - 9781665422543 UR - http://dx.doi.org/10.1109/icece51571.2020.9393057 DB - Crossref KW - Solar Pipe Light KW - Daylight Factor KW - minimum Daylight Autonomy KW - Useful Daylight Illuminance KW - alternative lighting KW - sustainability ER - TY - CONF TI - Analog Signal Processing Based Hardware Implementation of Real-Time Audio Visualizer AU - Shuvo, Shuvangkar AU - Akib, Abir Ahsan AU - Rahman, Mohammad Mahinur AU - Islam, Tanveerul AU - Rashid, Raihan Ur AU - Mahnaz, Saraf AU - Anwar, Md Shakil AU - Fattah, Shaikh Anowarul AU - Shahnaz, Celia T2 - 2020 IEEE Region 10 Symposium (TENSYMP) AB - Of late, signal processing is having an impact on a wide range of applications, from general radio signal processing and transmission to sophisticated biomedical applications. Despite not being as popular as its digital counterpart, analog signal processing has great applications in sound signal processing, noise elimination, biomedical signal processing and provides a cheap and effective alternative to digital signal processing. This paper proposes an application of analog audio signal processing for entertainment. The proposed design includes splitting of the audio spectrum by 2 nd order Chebyshev filters into eight distinct spectra, processing of the spectrum and visually implementing them on a twelve storied building in realtime using Christmas lights. This is an exemplary work of application of analog signal processing using analog circuitry in the entertainment industry. C2 - 2020/// C3 - 2020 IEEE Region 10 Symposium (TENSYMP) CY - Dhaka, Bangladesh DA - 2020/// PY - 2020/6/5/ DO - 10.1109/tensymp50017.2020.9230976 PB - IEEE SN - 9781728173665 UR - http://dx.doi.org/10.1109/tensymp50017.2020.9230976 ER - TY - CONF TI - Development of 3.3 kV-Capable, Open-Source, Low Cost Packaging Solution for Sic Transistor and Diode Testing AU - Cheng, Tzu-Hsuan AU - Mehrotra, Utkarsh AU - Hopkins, Douglas C. T2 - Power America Institute Annual Meeting C2 - 2020/2/25/ CY - Raleigh, NC DA - 2020/2/25/ PY - 2020/2/25/ ER - TY - CONF TI - Dynamic and Thermal IOL Test Systems for 3.3kV-6.5kV Die Development AU - Murthy, Pranav AU - Mehrotra, Utkarsh AU - Yu, Wensong AU - Hopkins, Douglas C. T2 - Power America Institute Annual Meeting C2 - 2020/2/25/ CY - Raleigh, NC DA - 2020/2/25/ PY - 2020/2/25/ ER - TY - CONF TI - Traditional DBC-Based Power Modules for Test in Developing 3.3kV-15kV WBG Devices AU - Mehrotra, Utkarsh AU - Morgan, Adam AU - Hopkins, Douglas C. T2 - Power America Institute Annual Meeting C2 - 2020/2/25/ CY - Raleigh, NC DA - 2020/2/25/ PY - 2020/2/25/ ER - TY - SOUND TI - Creating a Fast Turn Lab to Package Developmental Power Devices with a Packaging Example AU - Hopkins, Douglas C. DA - 2020/8/3/ PY - 2020/8/3/ ER - TY - SOUND TI - ParaPower – Leveraging Finite Difference Simulator for Quick Thermal Design AU - Sinha, Sourish Sankar AU - Hopkins, Douglas C. DA - 2020/1/24/ PY - 2020/1/24/ M3 - Webinar ER - TY - CONF TI - Ultra-High Density Double-Sided Half Bridge Packaging AU - Hopkins, Douglas C. AU - Cheng, Tzu-Hsuan AU - Mehrotra, Utkarsh T2 - Power Sources Manufacturers Association (PSMA) Webinar Series / Applied Power Electronics Conference (APEC) C2 - 2020/7/23/ DA - 2020/7/23/ PY - 2020/7/23/ ER - TY - JOUR TI - Beamforming optimization of wideband MISO systems in the presence of mutual coupling AU - Saab, Sandy AU - Mezghani, Amine AU - Heath, Robert W., Jr. T2 - 2020 54TH ASILOMAR CONFERENCE ON SIGNALS, SYSTEMS, AND COMPUTERS AB - We introduce a mutual information based optimization for a two-port multiple-input single-output (MISO) antenna system. We develop a complete circuit-level analysis of a compact MISO system in the wideband regime. We design a physically realizable antenna array and study the impact of mutual coupling on the spectral efficiency. Then, we maximize the system's mutual information by optimizing the beamformer under two different power constraints, namely the total dissipated power and the available power of the amplifiers. By varying the inter-element antenna spacing, we present results for the achievable spectral efficiency under different power amplifier constraints. DA - 2020/// PY - 2020/// DO - 10.1109/IEEECONF51394.2020.9443408 SP - 1338-1341 SN - 1058-6393 KW - Mutual Coupling KW - Multi-band KW - Beamforming KW - MISO KW - Optimization KW - Wideband Antenna Array ER - TY - JOUR TI - Frequency Synchronization for Low Resolution Millimeter-Wave AU - Dreifuerst, Ryan M. AU - Heath, Robert W., Jr. AU - Kulkarni, Mandar N. AU - Zhang, Jianzhong Charlie T2 - 2020 54TH ASILOMAR CONFERENCE ON SIGNALS, SYSTEMS, AND COMPUTERS AB - Low resolution data converters can enable power efficient high bandwidth communication at millimeter-wave and terahertz frequencies. Synchronization of such systems is a critical step in accurate decoding, yet current approaches require long block lengths or fail to reach the Cramer Rao Bound (CRB).́ Prior solutions have traditionally been divided into two distinct focuses: algorithms and designed sequences for synchronization. In this paper, we develop a jointly optimized neural architecture for frequency synchronization from configurable sequences and estimators. Our proposed technique uses two neural networks to generate sequences and determine the carrier frequency offset of the sequence after propagating through a channel and applying one-bit quantization. Our simulations show that we can improve estimation performance at low signal to noise ratio (SNR) by up to 8dB at little cost compared to the same estimator without the sequence generator. Our proposed system is fast, efficient, and easily updated, allowing it to handle time-varying systems. In conclusion, we believe further investigation in jointly optimized pilot sequences and estimators will be fundamental to handling signal processing techniques with low resolution data converters. DA - 2020/// PY - 2020/// DO - 10.1109/IEEECONF51394.2020.9443378 SP - 314-318 SN - 1058-6393 KW - Carrier frequency offset KW - millimeter wave KW - deep learning KW - one-bit receivers ER - TY - JOUR TI - Energy- vs Spectral-Efficiency for Energy-Harvesting Hybrid RF/VLC Networks AU - Yapici, Yavuz AU - Guvenc, Ismail T2 - 2020 54TH ASILOMAR CONFERENCE ON SIGNALS, SYSTEMS, AND COMPUTERS AB - We consider a hybrid radio frequency (RF) / visible light communications (VLC) scenario where the RF link is empowered by the energy harvested during the VLC transmission. We take into account the power consumption of the access point (AP), which is composed of light emitting diodes (LEDs), while it is communicating with a far user over a two-hop hybrid RF/VLC link. In particular, we consider the energy efficiency of the end-to-end network in enhancing the energy-harvesting performance by choosing the optimal direct current (DC) bias, which is overlooked in the existing literature. To this end, we model the energy consumption of the commercially available LEDs, and formulate a joint energy- and spectral-efficiency optimization problem. The extreme cases of optimizing energy and spectral efficiency individually underscores the importance of optimizing the DC bias for a given joint (multi-objective) optimization problem. DA - 2020/// PY - 2020/// DO - 10.1109/IEEECONF51394.2020.9443343 SP - 1152-1156 SN - 1058-6393 KW - DC bias KW - energy efficiency KW - hybrid RF/VLC KW - multi-objective optimization KW - spectral efficiency ER - TY - JOUR TI - Characterization of Highly Thermally Conductive Organic Substrates for a Double-Sided Cooled Power Module AU - Cheng, Tzu-Hsuan AU - Nishiguchi, Kenji AU - Fukawa, Yoshi AU - Baliga, B. Jayant AU - Bhattacharya, Subhashish AU - Hopkins, Douglas C. T2 - International Symposium on Microelectronics AB - Abstract Silicon-Carbide (SiC) power devices have become a promising option for traditional Silicon (Si) due to the superior material properties. To fully take advantage of the SiC devices, a high-performance power device packaging solution is necessary. This study proposes a cost-effective double-sided cooled (DSC) 1.2 kV SiC half-bridge power module using organic epoxy-resin composite dielectric (ERCD) substrates. The high mechanical and thermal performance of the power module is achieved by the low-modulus, moderate thermal conductivity, and relatively thin (120 μm) layer of ERCD material compared with traditional metal-clad ceramic approaches. This novel organic dielectric can withstand high voltage (5 kV @ 120 μm) and operate up to 250°C continuously, which is indispensable for high power applications. The thermal modeling results show that the equivalent thermal resistance junction-to-case (Rjc_eq) of the DSC power module using dual direct bonded copper (DBC) is 17% higher than the dual ERCD configuration. Furthermore, a non-insulated DSC power module concept is proposed for maximizing thermal performance by considering thermal vias in the ERCD substrate and direct-soldered heat sink. A thought process for optimization of thermal via design is demonstrated and it shows up to 24% of improvement on thermal performance compared with the insulated DSC power module. DA - 2020/9/1/ PY - 2020/9/1/ DO - 10.4071/2380-4505-2020.1.000277 VL - 2020 IS - 1 SP - 000277-000281 LA - en OP - SN - 2380-4505 UR - http://dx.doi.org/10.4071/2380-4505-2020.1.000277 DB - Crossref ER - TY - CONF TI - High Current Medium Voltage Bidirectional Solid State Circuit Breaker using SiC JFET Super Cascode AU - Mehrotra, Utkarsh AU - Ballard, Bahji AU - Hopkins, Douglas C. T2 - 2020 IEEE Energy Conversion Congress and Exposition (ECCE) AB - DC power systems found in electric transport, data centers and residential microgrid applications maintain a demand for fast, reliable and efficient power electronics in the Medium Voltage (MV) range. DC systems are inherently more sensitive to faults due to low system impedance and voltage sensitivity of accompanying power electronics creating a need for a fast all Solid State approach to system protection. This paper proposes a Bidirectional Solid State Circuit Breaker (BSSCB) utilizing the SuperCascode topology as the breaking element and has parallel transient energy absorption circuitry comprising of MOVs and snubbers to denergize the line upon fault. The paper discusses critical design points in breaker design, advantages of SuperCascode switch for breaker applications and power stage scaling calculations of the transient absorption circuitry. For packaging, a novel Epoxy Resin Composite Dielectric (ERCD) is considered as an alternative to metal-clad ceramic (DBC) substrate for higher reliability. The paper studies transient heat transfer in the power module using finite element analysis (FEA) and proposes a thermally defined and digitally controlled fuse curve for breakers. A design example of 10kV/100 A BSSCB is provided which holds 10x rated current for a 5ms dwell. A scaled-down 6kV/10A SSCB prototype using TO-247 packaged dies is demonstrated and is capable of withstanding 7x over-current for 1μs and short circuit interruption in approximately 60 ns. C2 - 2020/10/11/ C3 - 2020 IEEE Energy Conversion Congress and Exposition (ECCE) CY - Detroit, MI DA - 2020/10/11/ PY - 2020/10/11/ DO - 10.1109/ecce44975.2020.9236347 PB - IEEE SN - 9781728158266 UR - http://dx.doi.org/10.1109/ecce44975.2020.9236347 ER - TY - JOUR TI - Lithium Battery Cell Level Fusing with Aluminum Heavy Wire Bonds AU - Mehrotra, Utkarsh AU - Brazzle, Arthur AU - McKeown, Michael AU - Hopkins, Douglas C. T2 - International Symposium on Microelectronics AB - Abstract Aluminum heavy wire bonds interconnects are a potential alternative to laser or resistance welded bus bars due to its ease of manufacturability, long term reliability and low cost for battery banks. They can also be utilized as a fault protection solution in case of a surge current, dead short, etc, and to isolate a bad cell preventing synchronous failure. Typically, the current-carrying capability of a wire is estimated using standard data generated by testing in free air. However, a deviation in the capacity limits can occur due to the proximity of interconnect to larger thermal masses and different heat extraction techniques found in present day lithium battery packs; e.g., fluid channel cooling, encapsulated wires, etc. The cylindrical cell cathode, anode, and the busbar material constitute a large thermal mass to increase the fusing current in wire bonds above conventional levels. To better predict and design the interconnects advanced and system-specific models should be developed. This paper presents a new mathematical approach which includes the effect of convective cooling inside the battery pack to do an early step estimation of the current handling capacity and fusing time of different diameter wires. The paper also presents a finite element model that includes the impact of boundary conditions, wire length and wire diameter on steady-state current handling capacity of 99.99 % Al wire. Both steady-state and transient simulations were performed to estimate fusing times at different time rated conditions. The paper concludes by providing new curve-fit patterns to give future battery pack designers further insight aiding new designs. DA - 2020/9/1/ PY - 2020/9/1/ DO - 10.4071/2380-4505-2020.1.000009 VL - 2020 IS - 1 SP - 000009-000014 LA - en OP - SN - 2380-4505 UR - http://dx.doi.org/10.4071/2380-4505-2020.1.000009 DB - Crossref ER - TY - CONF TI - Optimized Highly Efficient SSCB Using Organic Substrate Packaging for Electric Vehicle Applications AU - Mehrotra, Utkarsh AU - Ballard, Bahji AU - Cheng, Tzu-Hsuan AU - Baliga, B. Jayant AU - Bhattacharya, Subhashish AU - Hopkins, Douglas C. T2 - 2020 IEEE Transportation Electrification Conference & Expo (ITEC) AB - Solid State Circuit Breakers (SSCBs) are an attractive protection solution for their arcless current interruption and fast actuation speeds over mechanical breakers. This paper proposes a Bidirectional SSCB (BSSCB) with a thermally defined and digitally controlled current time profile for fault protection in EV and other low-voltage DC systems. The paper proposes an organic packaging approach utilizing flex circuitry to develop a reliable, cost-effective power module for BSSCBs. The paper studies transient heat transfer in the power modules using finite element analysis (FEA). An RC themal ladder network is extracted to define a fusing curve. To demonstrate and verify the design, a 1kV/50 A SiC MOSFET BSSCB prototype is fabricated and tested, having a power density of 60 W/cm 3 and 4x reduction in form factor over presently researched breakers. Also, given are results for 750 V/150 A operation showing interruption in 2.4 μs. C2 - 2020/6// C3 - 2020 IEEE Transportation Electrification Conference & Expo (ITEC) DA - 2020/6// DO - 10.1109/itec48692.2020.9161539 PB - IEEE SN - 9781728146294 UR - http://dx.doi.org/10.1109/itec48692.2020.9161539 DB - Crossref ER - TY - CONF TI - Packaging Development for a 1200V SiC BiDFET Switch Using Highly Thermally Conductive Organic Epoxy Laminate AU - Mehrotra, Utkarsh AU - Cheng, Tzu-Hsuan AU - Kanale, Ajit AU - Agarwal, Aditi AU - Han, Kijeong AU - Baliga, B. Jayant AU - Bhattacharya, Subhashish AU - Hopkins, Douglas C. T2 - 2020 32nd International Symposium on Power Semiconductor Devices and ICs (ISPSD) AB - A novel 1.2 kV/10A, 4H-SiC monolithic, bidirectional switch has been developed for use in cycloconverter applications to facilitate high-frequency direct AC-to-AC power conversion and enables new power converter topologies. A new packaging solution, utilizing a 100 μm flexible polyimide organic laminate substrate is developed to mitigate thermo-mechanical stress during power cycling and enable smaller form factor and lower cost. Multiphysics simulations and static tests were conducted to show performance characterization of the module and compare it against metallic substrates. A new organic laminate epoxy resin composite dielectric (ERCD) is also evaluated for superior thermal performance and shows 63% reduction in junction to case resistance compared to DBC substrates C2 - 2020/9// C3 - 2020 32nd International Symposium on Power Semiconductor Devices and ICs (ISPSD) DA - 2020/9// DO - 10.1109/ispsd46842.2020.9170116 PB - IEEE SN - 9781728148366 UR - http://dx.doi.org/10.1109/ispsd46842.2020.9170116 DB - Crossref ER - TY - JOUR TI - Adaptive Droop Control Method for Suppressing Circulating Currents in DC Microgrids AU - Ghanbari, Niloofar AU - Bhattacharya, Subhashish T2 - IEEE OPEN ACCESS JOURNAL OF POWER AND ENERGY AB - DC microgrids are introduced to reduce the conversion stages needed for connection of DC sources to the DC loads. They employ the droop control algorithm for managing the power flow from sources to the loads. However, the droop control functionality is affected by circuit parameters, especially line resistances. As a consequence, load sharing as the primary objective of the droop controller lacks accuracy. Parallel-connected converters have mismatched output voltages, resulting in circulating currents. This paper proposes an adaptive droop control algorithm for suppressing circulating currents in a low voltage DC microgrid. Line resistances are estimated through mathematical calculations and droop parameters are adjusted accordingly. Moreover, a distributed secondary controller is proposed to improve the load sharing accuracy and eliminate the effect of line resistances. The secondary controller shifts the droop controller voltage setpoint according to the converter current. Both of the proposed methods result in an accurate load sharing; Each of the participating converters has the rated current and consequently circulating current is suppressed. The effectiveness of the proposed method is verified through simulation and hardware-in-the-loop (HIL) setup. DA - 2020/// PY - 2020/// DO - 10.1109/OAJPE.2020.2974940 VL - 7 SP - 100-110 SN - 2687-7910 UR - https://doi.org/10.1109/OAJPE.2020.2974940 KW - Circulating current KW - dc microgrid KW - distributed control KW - droop control KW - hardware-in-the-loop (HIL) ER - TY - JOUR TI - Power Conversion With a Magnetically-Geared Permanent Magnet Generator for Low-Speed Wave Energy Converter AU - Hazra, Samir AU - Kamat, Prathamesh AU - Bhattacharya, Subhashish AU - Ouyang, Wen AU - Englebretson, Steven T2 - IEEE Transactions on Industry Applications AB - This article presents power conversion and control of a novel low-speed radial-flux magnetically-geared permanent magnet generator (MGPMG) for wave energy conversion. The generator designed and developed by ABB Corporate Research has a magnetic-gear integrated into the structure, which amplifies the low speed of a wave energy converter (WEC) to a high speed of a rotor facing the stator windings. The generator is designed with a large number of magnet poles and concentrated windings for a simpler and cost-effective design. However, due to the concentrated windings, the induced voltage contains a significant percentage of the harmonic component, which leads to the generation of harmonic power. The impact of the harmonic power on power conversion circuit design and ways to mitigate the effect is discussed. The power conversion system and controls are designed to experimentally verify the operation of a prototype 10-kW 30-r/min MGPMG, which is driven by an induction motor emulating the dynamics of an oscillating rotary WEC. Experimental results of power conversion including harmonic power, efficiency analysis, and energy storage integration are reported. DA - 2020/9// PY - 2020/9// DO - 10.1109/TIA.2020.2997640 VL - 56 IS - 5 SP - 5308-5318 UR - https://doi.org/10.1109/TIA.2020.2997640 KW - Generators KW - Rotors KW - Stator windings KW - Windings KW - Harmonic analysis KW - Magnetomechanical effects KW - Energy storage system KW - harmonic power KW - magnetically-geared permanent magnet generator KW - oscillating power KW - power converter design KW - wave energy ER - TY - JOUR TI - Machine Learning and Hardware security: Challenges and Opportunities -Invited Talk AU - Regazzoni, Francesco AU - Bhasin, Shivam AU - Pour, Amir Ali AU - Alshaer, Ihab AU - Aydin, Furkan AU - Aysu, Aydin AU - Beroulle, Vincent AU - Di Natale, Giorgio AU - Franzon, Paul AU - Hely, David AU - Homma, Naofumi AU - Ito, Akira AU - Jap, Dirmanto AU - Kashyap, Priyank AU - Polian, Ilia AU - Potluri, Seetal AU - Ueno, Rei AU - Vatajelu, Elena-Ioana AU - Yli-Mayry, Ville T2 - 2020 IEEE/ACM INTERNATIONAL CONFERENCE ON COMPUTER AIDED-DESIGN (ICCAD) AB - Machine learning techniques have significantly changed our lives. They helped improving our everyday routines, but they also demonstrated to be an extremely helpful tool for more advanced and complex applications. However, the implications of hardware security problems under a massive diffusion of machine learning techniques are still to be completely understood. This paper first highlights novel applications of machine learning for hardware security, such as evaluation of post quantum cryptography hardware and extraction of physically unclonable functions from neural networks. Later, practical model extraction attack based on electromagnetic side-channel measurements are demonstrated followed by a discussion of strategies to protect proprietary models by watermarking them. DA - 2020/// PY - 2020/// DO - 10.1145/3400302.3416260 SP - SN - 1933-7760 KW - machine learning KW - hardware security ER - TY - JOUR TI - BoMaNet: Boolean Masking of an Entire Neural Network AU - Dubey, Anuj AU - Cammarota, Rosario AU - Aysu, Aydin T2 - 2020 IEEE/ACM INTERNATIONAL CONFERENCE ON COMPUTER AIDED-DESIGN (ICCAD) AB - Recent work on stealing machine learning (ML) models from inference engines with physical side-channel attacks warrant an urgent need for effective side-channel defenses. This work proposes the first fully-masked neural network inference engine design. DA - 2020/// PY - 2020/// DO - 10.1145/3400302.3415649 SP - SN - 1933-7760 KW - Masking KW - neural networks KW - side-channel attacks KW - model stealing ER - TY - JOUR TI - Improved Rotor Position Estimation in Extended Back-EMF Based Position Sensorless Control for IPMSMs with Non-Sinusoidal Back-EMF AU - Kim, Heonyoung AU - Bhattacharya, Subhashish T2 - 2020 IEEE INDUSTRY APPLICATIONS SOCIETY ANNUAL MEETING AB - In terms of permanent magnet synchronous machine (PMSM) design, the limited number of stator and rotor slots distort the air-gap flux distribution and its effective length. It results in machine parameters varying with respect to the rotor position. The non-sinusoidal back-EMF, induced from the rotor flux linkage harmonics, introduces current harmonics when conventional d-q axis current controller is adopted. Consequently, it deteriorates the performance of the rotor position estimation in extended back-EMF based position sensorless control. It is because rotor position is estimated assuming sinusoidal machine current. Additionally, the harmonic currents introduces undesired losses which do not contribute to torque production. In this manner, a harmonic voltage injection based current control scheme is presented that results in sinusoidal machine current. It improves the performance of extended back-EMF based position sensorless control and mitigates the harmonic copper losses DA - 2020/// PY - 2020/// DO - 10.1109/IAS44978.2020.9334884 SP - SN - 0197-2618 KW - Permanent magnet synchronous machine KW - harmonic current losses KW - harmonic voltage injection KW - non-sinusoidal back-EMF KW - non-sinusoidal machine current KW - vector control KW - extended back-EMF KW - sensorless control ER - TY - JOUR TI - 2.3-kV, 5-A 4H-SiC Ti and Ni JBS Rectifiers manufactured in Commercial Foundry: Impact of Implant Lateral Straggle AU - Agarwal, Aditi AU - Han, Kijeong AU - Baliga, B. Jayant T2 - 2020 IEEE WORKSHOP ON WIDE BANDGAP POWER DEVICES AND APPLICATIONS IN ASIA (WIPDA ASIA) AB - This paper reports characteristics of 2.3-kV 5-A 4H-SiC Junction Barrier controlled Schottky (JBS) rectifiers manufactured in a 6-inch commercial foundry. Two types (Ni and Ti Schottky contact metal) of JBS rectifiers were successfully fabricated. The electrical performance of the Ni and Ti JBS rectifiers is compared at temperatures up to 150°C. The on-state voltage drop (@ 5 A) of the Ti devices increased from 1.4 to 1.8 V with increasing temperature while that for Ni devices increased from 2.0 to 2.3 V, maintaining values well below that of the SiC P-N junction as required for a JBS diode. The leakage current for the Ni JBS diodes remained below 2 nA @ 500V even up to 150°C. In contrast, an increase in leakage current to an acceptable level of 100 nA @ 500V was observed for the Ti JBS diodes at 150°C due to its lower barrier height. Analytical modelling indicated that lateral straggle of the P + ion-implant plays an important role in determining the measured on-state voltage drop and reverse leakage characteristics. Simulations were performed to confirm the effect of lateral implant straggle. The simulations demonstrated that lateral implant straggle increases the on-resistance and reduces the leakage current of the JBS rectifier but has no effect on the knee voltage. The experimental results in this paper demonstrate that 4H-SiC JBS rectifiers with 2.3 kV blocking voltage can be manufactured using either Ni or Ti Schottky contacts with excellent on-state voltage drop and leakage current up to 150°C. DA - 2020/// PY - 2020/// DO - 10.1109/WiPDAAsia49671.2020.9360272 SP - KW - Junction Barrier Schottky (JBS) rectifier KW - 4H-SiC KW - Schottky barrier KW - Ni Schottky contact KW - Ti Schottky contact KW - leakage current knee voltage KW - on-resistance ER - TY - JOUR TI - Achieving Short Circuit Capability for 600 V GaN FETs Using a Gate-Source-Shorted Si Depletion-Mode MOSFET in Series with the Source AU - Kanale, Ajit AU - Baliga, B. Jayant T2 - 2020 IEEE WORKSHOP ON WIDE BANDGAP POWER DEVICES AND APPLICATIONS IN ASIA (WIPDA ASIA) AB - Gallium Nitride FETs have poor short-circuit withstand capability at high DC bus voltages with on-state gate drive voltage. In this paper, the BaSIC(DMM) topology that employs a low voltage Si depletion-mode MOSFET (DMM) in series with source of the GaN FET is demonstrated to suppress the peak short-circuit current and extend the SC withstand time. Experimental results are provided for commercially available 600 V Cascode GaN FETs. The SC withstand time was increased from 0.33 μs to 4.35 μs at a drain bias of 400 V with gate bias of 8 V, an improvement by a factor of 13×. Under normal power circuit operating conditions, the BaSIC(DMM) topology produces a 29 % increase in on-resistance and almost no change in switching losses. DA - 2020/// PY - 2020/// DO - 10.1109/WiPDAAsia49671.2020.9360275 SP - KW - Gallium Nitride KW - BaSIC topology KW - power device KW - short-circuit KW - robustness KW - Sense voltage ER - TY - JOUR TI - Dislocation-Based Thermodynamic Models of V-Pits Formation and Strain Relaxation in InGaN/GaN Epilayers on Si Substrates AU - Khafagy, Khaled H. AU - Hatem, Tarek M. AU - Bedair, Salah M. T2 - TMS 2020 149TH ANNUAL MEETING & EXHIBITION SUPPLEMENTAL PROCEEDINGS AB - The strain relaxation mechanism in III-N materials is occurred through the motion of dislocationsDislocations that generated at III-N/Si interfaceInterface as a result of large mismatch in lattice and thermal expansion coefficients. As a result of the large lattice mismatch between different layers, the upper layer gets strained and with thicker layers, the strain energy increases until a thickness limit called the critical material thickness. Most of such dislocationsDislocations (threading dislocationsThreading dislocations ) penetrate the top surface forming V-pits defectsV-pits Defects at the top surface that relax the material. These V-pits directly affect the device efficiency, performance, and reliability. Therefore, in this paper, a thermodynamics-based model will be used to study the V-pits formulation and growth in the III-N (especially, InGaN-based materials). In this model, three types of energies are used under a balanced system to model the V-pit formation and growth. These energies are the strain energy in the InGaN epilayer, the destruction energy as a result of dislocation to form the V-pit, and the strain energy of the V-pits facets that generated during the facet nucleationNucleation . DA - 2020/// PY - 2020/// DO - 10.1007/978-3-030-36296-6_188 SP - 2057-2064 SN - 2367-1696 KW - Threading dislocations KW - III-Nitride relaxation KW - V-pits defects KW - Thermodynamics modeling ER - TY - JOUR TI - RANTT: A RISC-V Architecture Extension for the Number Theoretic Transform AU - Karabulut, Emre AU - Aysu, Aydin T2 - 2020 30TH INTERNATIONAL CONFERENCE ON FIELD-PROGRAMMABLE LOGIC AND APPLICATIONS (FPL) AB - Lattice-based cryptography has been growing in demand due to their quantum attack resiliency. Polynomial multiplication is a major computational bottleneck of lattice cryptosystems. To address the challenge, lattice-based cryptosystems use the Number Theoretic Transform (NTT). Although NTT reduces complexity, it is still a well-known computational bottleneck. At the same time, NTT arithmetic needs vary for different algorithms, motivating flexible solutions. Although there are prior hardware and software NTT designs, they do not simultaneously offer flexibility and efficiency. This work provides an efficient and flexible NTT solution through domain-specific architectural support on RISC-V. Rather than using instruction-set extensions with compiler modifications or loosely coupling a RISC-V core with an NTT co-processor, our proposal uses application-specific dynamic instruction scheduling, memory dependence prediction, and datapath optimizations. This allows achieving a direct translation of C code to optimized NTT executions. We demonstrate the flexibility of our approach by implementing the NTT used in several lattice-based cryptography protocols: NewHope, qTESLA, CRYSTALS-Kyber, CRYSTALS-Dilithium, and Falcon. The results on the FPGA technology show that the proposed design is respectively 6x, 40x, and 3x more efficient than the baseline solution, Berkeley Out-of-Order Machine, and a prior HW/SW co-design, while providing the needed flexibility. DA - 2020/// PY - 2020/// DO - 10.1109/FPL50879.2020.00016 SP - 26-32 SN - 1946-1488 KW - Lattice-Based Cryptography KW - RISC-V KW - NTT ER - TY - JOUR TI - A 20-33 GHz Direct-Conversion Transmitter in 45-nm SOI CMOS AU - Ren, Tiantong AU - Hari, Sandeep AU - Floyd, Brian A. T2 - 2020 IEEE BICMOS AND COMPOUND SEMICONDUCTOR INTEGRATED CIRCUITS AND TECHNOLOGY SYMPOSIUM (BCICTS) AB - This paper presents a 20-33 GHz direct-conversion transmitter implemented in 45-nm RFSOI CMOS technology. The transmitter features a divider-based quadrature clock generation circuit, two current-combined double-balanced mixers, and a balanced power amplifier (PA) employing stacked FETs. The transmitter chip achieves 19.1 to 22.4 dB of conversion gain with saturated output power of 16.7 to 20.4 dBm over 20 to 33 GHz at the differential output. Image rejection and carrier suppression are more than 29 dB and 36 dB after calibration. At a carrier frequency of 28 GHz, the transmitter chip achieves an error vector magnitude (EVM) of 5.1 % with 12 Gbps using 64-QAM. DA - 2020/// PY - 2020/// DO - 10.1109/BCICTS48439.2020.9392967 SP - UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85104680228&partnerID=MN8TOARS KW - Transmitter KW - wide-band KW - IQ modulator KW - Gilbert cell KW - power amplifier KW - CMOS SOI KW - millimeter-wave KW - 5G ER - TY - JOUR TI - Persistent Data Retention Models AU - Wang, Tiancong AU - Tuck, James T2 - arXiv preprint arXiv:2009.14705 DA - 2020/// PY - 2020/// ER - TY - CONF TI - WET: write efficient loop tiling for non-volatile main memory AU - Alshboul, Mohammad AU - Tuck, James AU - Solihin, Yan T2 - IEEE C2 - 2020/// C3 - 2020 57th ACM/IEEE Design Automation Conference (DAC) DA - 2020/// SP - 1-6 ER - TY - JOUR TI - Methods of crash recovery for data stored in non-volatile main memory AU - Solihin, Yan AU - Alshboul, Mohammad AU - Tuck, James DA - 2020/3// PY - 2020/3// N1 - US Patent App. 16/564,479 RN - US Patent App. 16/564,479 ER - TY - JOUR TI - Application of Quantum Machine Learning to VLSI Placement AU - Turtletaub, Isaac AU - Li, George AU - Ibrahim, Mohannad AU - Franzon, Paul T2 - PROCEEDINGS OF THE 2020 ACM/IEEE 2ND WORKSHOP ON MACHINE LEARNING FOR CAD (MLCAD '20) AB - Considerable advances in quantum computing with functioning noisy, near-term devices have allowed for the application space to grow as a emerging field for problems with large solution spaces. However, current quantum hardware is limited in scale and noisy in generated data, necessitating hybrid quantum-classical solutions for viability of results and convergence. A quantum backend generates data for classical algorithms to optimize control parameters with, creating a hybrid quantum-classical computing loop. VLSI placement problems have shown potential for utilization, where traditionally heuristic solutions such as Kernighan-Lin (KL) are used. The Variational Quantum Eigensolver (VQE) is used to formulate a recursive Balanced Min-Cut (BMC) algorithm, and we suggest that quantum machine learning techniques can lower error rates and allow for faster convergence to an optimal solution. DA - 2020/// PY - 2020/// DO - 10.1145/3380446.3430644 SP - 61-66 KW - Quantum Machine Learning KW - Balanced Min-Cut KW - Variational Quantum Eigensolver KW - Recursive Partitioning Placement ER - TY - JOUR TI - Design Rule Checking with a CNN Based Feature Extractor AU - Francisco, Luis AU - Lagare, Tanmay AU - Jain, Arpit AU - Chaudhary, Somal AU - Kulkarni, Madhura AU - Sardana, Divya AU - Davis, W. Rhett AU - Franzon, Paul T2 - PROCEEDINGS OF THE 2020 ACM/IEEE 2ND WORKSHOP ON MACHINE LEARNING FOR CAD (MLCAD '20) AB - Design rule checking (DRC) is getting increasingly complex in advanced nodes technologies. It would be highly desirable to have a fast interactive DRC engine that could be used during layout. In this work, we establish the proof of feasibility for such an engine. The proposed model consists of a convolutional neural network (CNN) trained to detect DRC violations. The model was trained with artificial data that was derived from a set of 50 SRAM designs. The focus in this demonstration was metal 1 rules. Using this solution, we can detect multiple DRC violations 32x faster than Boolean checkers with an accuracy of up to 92%. The proposed solution can be easily expanded to a complete rule set. DA - 2020/// PY - 2020/// DO - 10.1145/3380446.3430625 SP - 9-14 KW - Design Rule Checking KW - Machine Learning KW - IC Verification KW - Design for Manufacturing KW - Convolutional Neural Network KW - Deep Learning ER - TY - JOUR TI - Artificial Intelligence Assisted Collaborative Edge Caching in Small Cell Networks AU - Pervej, Md Ferdous AU - Tan, Le Thanh AU - Hu, Rose Qingyang T2 - 2020 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM) AB - Edge caching is a new paradigm that has been exploited over the past several years to reduce the load for the core network and to enhance the content delivery performance. Many existing caching solutions only consider homogeneous caching placement due to the immense complexity associated with the heterogeneous caching models. Unlike these legacy modeling paradigms, this paper considers heterogeneous content preference of the users with heterogeneous caching models at the edge nodes. Besides, aiming to maximize the cache hit ratio (CHR) in a two-tier heterogeneous network, we let the edge nodes collaborate. However, due to complex combinatorial decision variables, the formulated problem is hard to solve in the polynomial time. Moreover, there does not even exist a ready-touse tool or software to solve the problem. We propose a modified particle swarm optimization (M-PSO) algorithm that efficiently solves the complex constraint problem in a reasonable time. Using numerical analysis and simulation, we validate that the proposed algorithm significantly enhances the CHR performance when comparing to that of the existing baseline caching schemes. DA - 2020/// PY - 2020/// DO - 10.1109/GLOBECOM42002.2020.9322101 SP - SN - 2576-6813 KW - Cache hit ratio KW - content delivery network KW - edge caching KW - particle swarm optimization KW - small cell network ER - TY - JOUR TI - Lighter and Stronger: Cofabricated Electrodes and Variable Stiffness Elements in Dielectric Actuators AU - Piskarev, Egor AU - Shintake, Jun AU - Ramachandran, Vivek AU - Baugh, Neil AU - Dickey, Michael D. AU - Floreano, Dario T2 - ADVANCED INTELLIGENT SYSTEMS AB - The inherent compliance of soft robots often makes it difficult for them to exert forces on surrounding surfaces or withstand mechanical loading. Controlled stiffness is a solution to empower soft robots with the ability to apply large forces on their environments and sustain external loads without deformations. Herein, a compact, soft actuator composed of a shared electrode used for both electrostatic actuation and variable stiffness is described. The device operates as a dielectric elastomer actuator, while variable stiffness is provided by a shared electrode made of gallium. The fabricated actuator, namely variable stiffness dielectric elastomer actuator (VSDEA), has a compact and lightweight structure with a thickness of 930 μm and a mass of 0.7 g. It exhibits a stiffness change of 183×, a bending angle of 31°, and a blocked force of 0.65 mN. Thanks to the lightweight feature, the stiffness change per mass of the actuator (261× g −1 ) is 2.6 times higher than that of the other type of VSDEA that has no shared electrode. DA - 2020/10// PY - 2020/10// DO - 10.1002/aisy.202000069 VL - 2 IS - 10 SP - SN - 2640-4567 KW - dielectric elastomer actuators KW - gallium KW - liquid metals KW - soft robotics KW - variable stiffnesses ER - TY - JOUR TI - GPU-FPtuner: Mixed-precision Auto-tuning for Floating-point Applications on GPU AU - Gu, Ruidong AU - Becchi, Michela T2 - 2020 IEEE 27TH INTERNATIONAL CONFERENCE ON HIGH PERFORMANCE COMPUTING, DATA, AND ANALYTICS (HIPC 2020) AB - GPUs have been extensively used to accelerate scientific applications from a variety of domains: computational fluid dynamics, astronomy and astrophysics, climate modeling, numerical analysis, to name a few. Many of these applications rely on floating-point arithmetic, which is approximate in nature. High-precision libraries have been proposed to mitigate accuracy issues due to the use of floating-point arithmetic. However, these libraries offer increased accuracy at a significant performance cost. Previous work, primarily focusing on CPU code and on standard IEEE floating-point data types, has explored mixed precision as a compromise between performance and accuracy. In this work, we propose a mixed precision autotuner for GPU applications that rely on floating-point arithmetic. Our tool supports standard 32- and 64-bit floating-point arithmetic, as well as high precision through the QD library. Our autotuner relies on compiler analysis to reduce the size of the tuning space. In particular, our tuning strategy takes into account code patterns prone to error propagation and GPU-specific considerations to generate a tuning plan that balances performance and accuracy. Our autotuner pipeline, implemented using the ROSE compiler and Python scripts, is fully automated and the code is available in open source. Our experimental results collected on benchmark applications with various code complexities show performance-accuracy tradeoffs for these applications and the effectiveness of our tool in identifying representative tuning points. DA - 2020/// PY - 2020/// DO - 10.1109/HiPC50609.2020.00043 SP - 294-304 SN - 1094-7256 KW - GPU KW - floating-point arithmetic KW - mixed-precision arithmetic KW - accuracy KW - performance KW - autotuning ER - TY - JOUR TI - Traffic Shifting based Resource Optimization in Aggregated IoT Communication AU - Chapnevis, Amirahmad AU - Guvenc, Ismail AU - Bulut, Eyuphan T2 - PROCEEDINGS OF THE 2020 IEEE 45TH CONFERENCE ON LOCAL COMPUTER NETWORKS (LCN 2020) AB - Aggregated Internet of Things (IoT) communication aims to use core network resources efficiently by providing cellular access to a group of IoT devices over the same subscriber identity. Leveraging the low data rates and long data sending intervals of IoT devices, several of the IoT devices in the same serving area of the core network are grouped together and take turns to send their data to their servers without causing overlaps in their communication. In this paper, we take this approach further and benefiting from the flexibility in data sending schedules, we aim to increase savings in cellular resources by shifting (delaying or performing earlier) the regular traffic patterns of IoT devices slightly. To this end, we consider two different traffic shifting models, namely, consistent and inconsistent shifting. We first solve the optimal aggregation of IoT devices under each model by using Integer Linear Programming (ILP). In order to avoid the high complexity of ILP solution, we then develop a heuristic based solution that runs in polynomial time. Through simulations, we show that heuristic based solution provides close to optimal results in various scenarios and shifting based aggregated communication offers more resource optimization (i.e., smaller number of bearers needed to connect all IoT devices) than the aggregated communication with no shifting. DA - 2020/// PY - 2020/// DO - 10.1109/LCN48667.2020.9314781 SP - 233-243 SN - 0742-1303 KW - 5G KW - cellular network KW - clustering KW - core network KW - Internet of Things (IoT) KW - machine type communications (MTC) ER - TY - JOUR TI - Guarantees for Mix-flows in Inter-Datacenter WANs in Single and Federated Clouds AU - Gandhi, Shruti AU - Viniotis, Yannis T2 - PROCEEDINGS OF THE 2020 IEEE 45TH CONFERENCE ON LOCAL COMPUTER NETWORKS (LCN 2020) AB - Inter-datacenter WANs connect geo-distributed datacenters and carry a considerable amount of traffic, generally a mix of flows. There has been little work done to provide custom guarantees depending on the nature of traffic requirements in such environments. In this paper we address this problem by proposing Vritti, an adaptable spatial-temporal system for traffic engineering in inter-datacenter WAN environments applicable to single and federated clouds. With Vritti, cloud providers can offer tailor-made guarantees to users with widely differing requirements (in terms of hard, soft or no deadlines) and traffic characteristics (in terms of known or unknown traffic volumes). We use linear programming to mathematically formulate the problem with the objective of maximizing utility. We propose two online algorithms to generate admission control, scheduling and routing decisions. Our simulations show that Vritti can effectively meet deadline transfers and provide fairness to non-deadline transfers in both single and federated cloud environments. DA - 2020/// PY - 2020/// DO - 10.1109/LCN48667.2020.9314789 SP - 244-255 SN - 0742-1303 KW - Inter-datacenter WAN KW - mix-flows KW - tailor-made guarantees KW - deadlines ER - TY - JOUR TI - An investigation of THz label-free opioid sensing AU - Zhang, W-D AU - Bykhovski, A. AU - Himed, L. AU - Yan, Z-G AU - Brown, E. R. T2 - 2020 45TH INTERNATIONAL CONFERENCE ON INFRARED, MILLIMETER, AND TERAHERTZ WAVES (IRMMW-THZ) AB - We present numerical modeling and experiments on the THz electromagnetic signatures of various opioid powders. DA - 2020/// PY - 2020/// DO - 10.1109/IRMMW-THZ46771.2020.9370421 SP - SN - 2162-2027 ER - TY - JOUR TI - Characterizing the Impact of TCP Coexistence in Data Center Networks AU - Ganji, Anirudh AU - Singh, Anand AU - Shahzad, Muhammad T2 - 2020 IEEE 40TH INTERNATIONAL CONFERENCE ON DISTRIBUTED COMPUTING SYSTEMS (ICDCS) AB - The switch fabrics of today's data centers carry traffic controlled by a variety of TCP congestion control algorithms. This leads us to ask: how does the coexistence of multiple variants of TCP on shared switch fabric impacts the performance achieved by different applications in data centers? To answer this question, we conducted an extensive set of experiments with coexisting TCP variants on Leaf-Spine and Fat-Tree switch fabrics. We executed common data center workloads, which include streaming, MapReduce, and storage workloads, using four commonly used TCP variants, namely BBR, DCTCP, CUBIC, and New Reno. We also extensively executed iPerf workloads using these 4 TCP variants to purely study the impact of the coexistence of TCP variants on each other's performance without incorporating the network behavior of the application layer. Our experiments resulted in a large set of network traces comprised of 160 billion packets (we will release these traces after publication of this work). We present comprehensive observations from these traces that have important implications in ensuring optimal utilization of data center switch fabric and in meeting the network performance needs of application layer workloads. DA - 2020/// PY - 2020/// DO - 10.1109/ICDCS47774.2020.00035 SP - 388-398 SN - 1063-6927 ER - TY - JOUR TI - Optimizing Complex OpenCL Code for FPGA: A Case Study on Finite Automata Traversal AU - Nourian, Marziyeh AU - Zarch, Mostafa Eghbali AU - Becchi, Michela T2 - 2020 IEEE 26TH INTERNATIONAL CONFERENCE ON PARALLEL AND DISTRIBUTED SYSTEMS (ICPADS) AB - While FPGAs have been traditionally considered hard to program, recently there have been efforts aimed to allow the use of high-level programming models and libraries intended for multi-core CPUs and GPUs to program FPGAs. For example, both Intel and Xilinx are now providing toolchains to deploy OpenCL code onto FPGA. However, because the nature of the parallelism offered by GPU and FPGA devices is fundamentally different, OpenCL code optimized for GPU can prove very inefficient on FPGA, in terms of both performance and hardware resource utilization. This paper explores this problem on finite automata traversal. In particular, we consider an OpenCL NFA traversal kernel optimized for GPU but exhibiting FPGA-friendly characteristics, namely: limited memory requirements, lack of synchronization, and SIMD execution. We explore a set of structural code changes, custom and best-practice optimizations to retarget this code to FPGA. We showcase the effect of these optimizations on an Intel Stratix V FPGA board using various NFA topologies from different application domains. Our evaluation shows that, while the resource requirements of the original code exceed the capacity of the FPGA in use, our optimizations lead to significant resource savings and allow the transformed code to fit the FPGA for all considered NFA topologies. In addition, our optimizations lead to speedups up to 4x over an already optimized code-variant aimed to fit the NFA traversal kernel on FPGA. Some of the proposed optimizations can be generalized for other applications and introduced in OpenCL-to-FPGA compiler. DA - 2020/// PY - 2020/// DO - 10.1109/ICPADS51040.2020.00073 SP - 518-527 SN - 1521-9097 KW - OpenCL KW - FPGA KW - high-level synthesis KW - automata processing KW - NFA KW - performance optimization ER - TY - JOUR TI - Performance Analysis and Improvement on DSRC Application for V2V Communication AU - Cao, Liu AU - Yin, Hao AU - Hu, Jie AU - Zhang, Lyutianyang T2 - 2020 IEEE 92ND VEHICULAR TECHNOLOGY CONFERENCE (VTC2020-FALL) AB - In this paper, we focus on the performance of vehicle-to-vehicle (V2V) communication adopting the Dedicated Short Range Communication (DSRC) application in periodic broadcast mode. An analytical model is studied and a fixed point method is used to analyze the packet delivery ratio (PDR) and mean delay based on the IEEE 802.11p standard in a fully connected network under the assumption of perfect PHY performance. With the characteristics of V2V communication, we develop the Semi-persistent Contention Density Control (SpCDC) scheme to improve the DSRC performance. We use Monte Carlo simulation to verify the results obtained by the analytical model. The simulation results show that the packet delivery ratio in SpCDC scheme increases more than 10% compared with IEEE 802.11p in heavy vehicle load scenarios. Meanwhile, the mean reception delay decreases more than 50%, which provides more reliable road safety. DA - 2020/// PY - 2020/// DO - 10.1109/VTC2020-Fall49728.2020.9348743 SP - KW - V2V KW - DSRC KW - IEEE 802.11p KW - DCF KW - MAC design ER - TY - JOUR TI - Eco-Vehicular Edge Networks for Connected Transportation: A Distributed Multi-Agent Reinforcement Learning Approach AU - Pervej, Md Ferdous AU - Lin, Shih-Chun T2 - 2020 IEEE 92ND VEHICULAR TECHNOLOGY CONFERENCE (VTC2020-FALL) AB - This paper introduces an energy-efficient, software-defined vehicular edge network for the growing intelligent connected transportation system. A joint user-centric virtual cell formation and resource allocation problem is investigated to bring eco-solutions at the edge. This joint problem aims to combat against the power-hungry edge nodes while maintaining assured reliability and data rate. More specifically, by prioritizing the downlink communication of dynamic eco-routing, highly mobile autonomous vehicles are served with multiple low-powered access points (APs) simultaneously for ubiquitous connectivity and guaranteed reliability of the network. The formulated optimization is exceptionally troublesome to solve within a polynomial time, due to its complicated combinatorial structure. Hence, a distributed multi-agent reinforcement learning (D-MARL) algorithm is proposed for eco-vehicular edges, where multiple agents cooperatively learn to receive the best reward. First, the algorithm segments the centralized action space into multiple smaller groups. Based on the model-free distributed Q learner, each edge agent takes its actions from the respective group. Also, in each learning state, a software-defined controller chooses the global best action from individual bests of the distributed agents. Numerical results validate that our learning solution achieves near-optimal performances within a small number of training episodes as compared with existing baselines. DA - 2020/// PY - 2020/// DO - 10.1109/VTC2020-Fall49728.2020.9348507 SP - KW - Connected transportation KW - energy efficiency KW - reinforcement learning KW - resource scheduling KW - software-defined networking KW - vehicle-to-infrastructure (V2I) communication ER - TY - JOUR TI - A Framework for Developing Algorithms for Estimating Propagation Parameters from Measurements AU - Sayeed, Akbar AU - Vouras, Peter AU - Gentile, Camillo AU - Weiss, Alec AU - Quimby, Jeanne AU - Cheng, Zihang AU - Modad, Bassel AU - Zhang, Yuning AU - Anjinappa, Chethan AU - Erden, Fatih AU - Ozdemir, Ozgur AU - Mueller, Robert AU - Dupleich, Diego AU - Niu, Han AU - Michelson, David AU - Hughes, Aidan T2 - 2020 IEEE GLOBECOM WORKSHOPS (GC WKSHPS) AB - A framework is proposed for developing and evaluating algorithms for extracting multipath propagation components (MPCs) from measurements collected by sounders at millimeter-wave (mmW) frequencies. To focus on algorithmic performance, an idealized model is proposed for the spatial frequency response of the propagation environment measured by a sounder. The input to the sounder model is a pre-determined set of MPC parameters that serve as the “ground truth”. A three-dimensional angle-delay (beamspace) representation of the measured spatial frequency response serves as a natural domain for implementing and analyzing MPC extraction algorithms. Metrics for quantifying the error in estimated MPC parameters are introduced. Initial results are presented for a greedy matching pursuit algorithm that performs a least-squares (LS) reconstruction of the MPC path gains within the iterations. The results indicate that the simple greedy-LS algorithm has the ability to extract MPCs over a large dynamic range, and suggest several avenues for further performance improvement through extensions of the greedy-LS algorithm as well as by incorporating features of other algorithms, such as SAGE and RIMAX. DA - 2020/// PY - 2020/// DO - 10.1109/GCWkshps50303.2020.9367404 SP - SN - 2166-0069 ER - TY - JOUR TI - Design of a Forensic Enabled Secure Cloud Logging AU - Rane, Sagar AU - Wagh, Sanjeev AU - Dixit, Arati T2 - PROCEEDINGS OF THE 21ST INTERNATIONAL CONFERENCE ON DISTRIBUTED COMPUTING AND NETWORKING (ICDCN 2020) AB - Adoption of cloud computing services greatly reduce the cost of managing businesses and increase the productivity. But, due to complex network configurations of cloud, it is a vector for various malicious attacks. Logs are the most valuable element which can be helpful in revealing the insights of any activity happened in cloud. Experienced attackers and malicious users always targets to destroy logging service first, after their attacks to remain untraceable. The existing logging techniques, which consider logger as a trusted stakeholder cannot be applied in cloud as there is possibility of collusion in between logger of cloud i.e. cloud service provider and fraud cloud service consumer or cloud forensic investigators to falsify the logs. DA - 2020/// PY - 2020/// DO - 10.1145/3369740.3373803 SP - KW - Cloud Forensics KW - Forensic Investigation KW - Cloud Security KW - Blockchain KW - Interplanetary File System (IPFS) ER - TY - JOUR TI - Investigation of Ringing Effects on Phase Shift Keyed Direct Antenna Modulation Transmitters AU - Huang, Danyang AU - Adams, Jacob J. AU - Schab, Kurt T2 - 2020 IEEE INTERNATIONAL SYMPOSIUM ON ANTENNAS AND PROPAGATION AND NORTH AMERICAN RADIO SCIENCE MEETING AB - In this paper, a method of direct antenna modulation (DAM) transmitting phase shift keyed (PSK) high data rate signals using a narrowband antenna is described. We analyze the result of an over the air DAM PSK measurement and degradation are observed in QPSK DAM compared to the ideal case. We demonstrate that it is the parasitics of the circuit that reduce the ability of the system to store voltage and achieve fast transitions, particularly between certain combinations of symbols. This degradation is studied and it can be predicted by circuit model simulation. DA - 2020/// PY - 2020/// DO - 10.1109/IEEECONF35879.2020.9330246 SP - 1817-1818 SN - 1522-3965 ER - TY - JOUR TI - A Decoupling Network Based on Characteristic Port Modes AU - Yang, Binbin AU - Adams, Jacob J. T2 - 2020 IEEE INTERNATIONAL SYMPOSIUM ON ANTENNAS AND PROPAGATION AND NORTH AMERICAN RADIO SCIENCE MEETING AB - In this paper, we present a novel decoupling network for coupled antenna systems using characteristic port modes. Specifically, we observe that the the port response of a multiport antenna is the superposition of the characteristic modal responses, while the superposition relation for multi-port antennas can be represented as a transformer bank. By developing a transformer network that inverts the superposition relation, we realize a decoupling network for the coupled multi-port antennas. Depending on the antenna's property, this decoupling network could be a broadband, e.g. for symmetric networks, or a narrowband realization. DA - 2020/// PY - 2020/// DO - 10.1109/IEEECONF35879.2020.9329790 SP - 1667-1668 SN - 1522-3965 ER - TY - JOUR TI - Design of a 3D Printed Gradient Index Lens Using High Permittivity Ceramic AU - Oh, Yongduk AU - Bharambe, Vivek T. AU - Adams, Jacob J. AU - Negro, Dylan AU - MacDonald, Eric T2 - 2020 IEEE INTERNATIONAL SYMPOSIUM ON ANTENNAS AND PROPAGATION AND NORTH AMERICAN RADIO SCIENCE MEETING AB - In this paper, we investigate the design of a gradient index (GRIN) horn-integrated lens using a zircona lattice printed using a Nanoparticle Jetting process. The electrical properties of the ZrO 2 lattice for a range of geometric parameters are simulated to realize a range of effective dielectric constants from 3 - 23. The properties of a 3D printed lattice are found to be consistent with the simulations. A shortened horn antenna combined with a flat GRIN lens is designed to collimate the beam and enhance directivity. The simulated directivity is 14.6 dBi at 15 GHz, which is 6.2 dB higher than the same horn without the lens. DA - 2020/// PY - 2020/// DO - 10.1109/IEEECONF35879.2020.9330193 SP - 1431-1432 SN - 1522-3965 KW - 3D printing KW - zirconia KW - high dielectric constant KW - effective permittivity KW - GRIN lens ER - TY - JOUR TI - 3D Printed Zirconia for UWB Stacked Conical Ring DRA AU - Bharambe, Vivek T. AU - Oh, Yongduk AU - Adams, Jacob J. AU - Negro, Dylan AU - MacDonald, Eric T2 - 2020 IEEE INTERNATIONAL SYMPOSIUM ON ANTENNAS AND PROPAGATION AND NORTH AMERICAN RADIO SCIENCE MEETING AB - In this paper, we present a 3D printed ultrawideband (2.95 GHz-20 GHz) dielectric resonator antenna (DRA) fabricated using Nano-Particle Jetting (NPJ) of high permittivity, low loss, mechanically tough ceramic, zirconia. 3D printing enables fabrication of geometrically complex DRA design without machining or high pressure shaping. The wideband impedance response was achieved with a hybrid monopole/DRA design that uses the fundamental and higher order modes of the monopole and the parasitic DRA rings for a wide impedance bandwidth (VSWR <; 3). In the future, the 3D printing technique can enable building DRAs with more complex shapes or ceramic lattices to build graded index lenses. DA - 2020/// PY - 2020/// DO - 10.1109/IEEECONF35879.2020.9330248 SP - 41-42 SN - 1522-3965 KW - 3D Printing KW - zirconia KW - Dielectric Resonator Antenna KW - UWB antenna ER - TY - JOUR TI - A Circuit Model for Energy Synchronous Direct Antenna Modulation Using an Electrically Small Loop AU - Dusenbury, Joseph AU - Huang, Danyang AU - Adams, Jacob J. T2 - 2020 IEEE INTERNATIONAL SYMPOSIUM ON ANTENNAS AND PROPAGATION AND NORTH AMERICAN RADIO SCIENCE MEETING AB - A simple circuit model for a broadband electrically small loop transmitter using energy synchronous direct antenna modulation (DAM) is presented. The concept of energy-synchronous DAM using a loop antenna is briefly described and compared to a conventional narrowband transmitter, via time domain simulations of the current on the loop. A brief analysis of the affect of ohmic loss on the stored current is presented. Initial results suggest that the dissipation in the loop is negligible over short symbol durations, but motivates a discussion about the need for a more comprehensive parametric study for this class of DAM transmitters. DA - 2020/// PY - 2020/// DO - 10.1109/IEEECONF35879.2020.9329560 SP - 459-460 SN - 1522-3965 KW - direct antenna modulation KW - loop antenna KW - inductive energy ER - TY - JOUR TI - GPU-Based Static Data-Flow Analysis for Fast and Scalable Android App Vetting AU - Yu, Xiaodong AU - Wei, Fengguo AU - Ou, Xinming AU - Becchi, Michela AU - Bicer, Tekin AU - Yao, Danfeng T2 - 2020 IEEE 34TH INTERNATIONAL PARALLEL AND DISTRIBUTED PROCESSING SYMPOSIUM IPDPS 2020 AB - Many popular vetting tools for Android applications use static code analysis techniques. In particular, Interprocedural Data-Flow Graph (IDFG) construction is the computation at the core of Android static data-flow analysis and consumes most of the analysis time. Many analysis tools use a worklist algorithm, an iterative fixed-point approach, to construct the IDFG. In this paper, we observe that a straightforward GPU parallelization of the worklist algorithm leads to significant underutilization of the GPU resources. We identify four performance bottlenecks, namely, frequent dynamic memory allocations, high branch divergence, workload imbalance, and irregular memory access patterns. Accordingly, we propose GDroid, a GPU-based worklist algorithm implementation with multiple fine-grained optimizations tailored to common characteristics of Android applications. The optimizations considered are: matrix-based data structure, memory access-based node grouping, and worklist merging. Our experimental evaluation, performed on 1000 Android applications, shows that the proposed optimizations are beneficial to performance, and GDroid can achieve up to 128X speedups against a plain GPU implementation. DA - 2020/// PY - 2020/// DO - 10.1109/IPDPS47924.2020.00037 SP - 274-284 SN - 1530-2075 KW - GPU KW - static program analysis KW - data-flow analysis KW - Android security KW - mobile application vetting KW - worklist algorithm KW - application-specific optimization ER - TY - JOUR TI - Scalable and Fast Lazy Persistency on GPUs AU - Yudha, Ardhi Wiratama Baskara AU - Kimura, Keiji AU - Zhou, Huiyang AU - Solihin, Yan T2 - 2020 IEEE INTERNATIONAL SYMPOSIUM ON WORKLOAD CHARACTERIZATION (IISWC 2020) AB - GPUs applications, including many scientific and machine learning applications, increasingly demand larger memory capacity. NVM is promising higher density compared to DRAM and better future scaling potentials. Long running GPU applications can benefit from NVM by exploiting its persistency, allowing crash recovery of data in memory. In this paper, we propose mapping Lazy Persistency (LP) to GPUs and identify the design space of such mapping. We then characterize LP performance on GPUs, varying the checksum type, reduction method, use of locking, and hash table designs. Armed with insights into the performance bottlenecks, we propose a hash table-less method that performs well on hundreds and thousands of threads, achieving persistency with nearly negligible (2.1%) slowdown for a variety of representative benchmarks. We also propose a directive-based programming language support to simplify programming effort for adding LP to GPU applications. DA - 2020/// PY - 2020/// DO - 10.1109/IISWC50251.2020.00032 SP - 252-263 ER - TY - JOUR TI - Reliability Modeling of NISQ-Era Quantum Computers AU - Liu, Ji AU - Zhou, Huiyang T2 - 2020 IEEE INTERNATIONAL SYMPOSIUM ON WORKLOAD CHARACTERIZATION (IISWC 2020) AB - Recent developments in quantum computers have been pushing up the number of qubits. However, the state-of-the-art Noisy Intermediate Scale Quantum (NISQ) computers still do not have enough qubits to accommodate the error correction circuit. Noise in quantum gates limits the reliability of quantum circuits. To characterize the noise effects, prior methods such as process tomography, gateset tomography and randomized benchmarking have been proposed. However, the challenge is that these methods do not scale well with the number of qubits. Noise models based on the understanding of underneath physics have also been proposed to study different kinds of noise in quantum computers. The difficulty is that there is no widely accepted noise model that incorporates all different kinds of errors. The realworld errors can be very complicated and it remains an active area of research to produce accurate noise models. In this paper, instead of using noise models to estimate the reliability, which is measured with success rates or inference strength, we treat the NISQ quantum computer as a black box. We use several quantum circuit characteristics such as the number of qubits, circuit depth, the number of CNOT gates, and the connection topology of the quantum computer as inputs to the black box and derive a reliability estimation model using (1) polynomial fitting and (2) a shallow neural network. We propose randomized benchmarks with random numbers of qubits and basic gates to generate a large data set for neural network training. We show that the estimated reliability from our black-box model outperforms the noise models from Qiskit. We also showcase that our black-box model can be used to guide quantum circuit optimization at compile time. DA - 2020/// PY - 2020/// DO - 10.1109/IISWC50251.2020.00018 SP - 94-105 KW - NISQ quantum computer KW - reliability model KW - neural network ER - TY - JOUR TI - Evaluating Thread Coarsening and Low-cost Synchronization on Intel Xeon Phi AU - Wu, Hancheng AU - Becchi, Michela T2 - 2020 IEEE 34TH INTERNATIONAL PARALLEL AND DISTRIBUTED PROCESSING SYMPOSIUM IPDPS 2020 AB - Manycore processors such as GPUs and Intel Xeon Phis have become popular due to their massive parallelism and high power-efficiency. To achieve optimal performance, it is necessary to optimize the use of the compute cores and of the memory system available on these devices. Previous work has proposed techniques to improve the use of the GPU resources. While Intel Phi can provide massive parallelism through their x86 cores and vector units, optimization techniques for these platforms have received less consideration.In this work, we study the benefits of thread coarsening and low-cost synchronization on applications running on Intel Xeon Phi processors and encoded in SIMT fashion. Specifically, we explore thread coarsening as a way to remap the work to the available cores and vector lanes. In addition, we propose low- overhead synchronization primitives, such as atomic operations and barriers, which transparently apply to threads mapped to the same or different VPUs and x86 cores. Finally, we consider the combined use of thread coarsening and our proposed synchronization primitives. We evaluate the effect of these techniques on the performance of two kinds of kernels: collaborative and non-collaborative ones, the former using scratchpad memory to explicitly control data sharing among threads. Our evaluation leads to the following results. First, while not always beneficial for non-collaborative kernels, thread coarsening improves the performance of collaborative kernels consistently by reducing the synchronization overhead. Second, our synchronization primitives outperform standard pthread APIs by a factor up to 8x in real-world benchmarks. Last, the combined use of the proposed techniques leads to performance improvements, especially for collaborative kernels. DA - 2020/// PY - 2020/// DO - 10.1109/IPDPS47924.2020.00108 SP - 1018-1029 SN - 1530-2075 KW - SIMT KW - manycore processors KW - Intel Xeon Phi KW - thread coarsening KW - synchronization ER - TY - CONF TI - An Environmental Station with Bioimpedance Capabilities for Agricultural Deployment AU - Reynolds, James AU - Taggart, Matthew AU - Lobaton, Edgar AU - Daniele, Michael AU - Rufty, Thomas AU - Bozkurt, Alper AB - The majority of recent studies on precision agriculture have focused on a variety of imaging techniques to assess the phenotypical state of crops. This approach is limited by the time delay between the stressor occurrence and the visible physiological change and the dependence of measurements on weather conditions. As a novel and alternative method, we have developed a low-cost system combining the measurements of environmental parameters with tracking of the electrophysiological changes in the plant body. These include the measurement of photosynthetically active radiation, volumetric water content, ambient temperature, ambient relative humidity, and bioelectrical impedance of the plant. We demonstrate a potential application of this system for monitoring the diurnal behavior and drought response of plants. C2 - 2020/10/25/ C3 - 2020 IEEE SENSORS DA - 2020/10/25/ DO - 10.1109/sensors47125.2020.9278584 PB - IEEE UR - http://dx.doi.org/10.1109/sensors47125.2020.9278584 ER - TY - JOUR TI - A Loop-aware Autotuner for High-Precision Floating-point Applications AU - Gu, Ruidong AU - Beata, Paul AU - Becchi, Michela T2 - 2020 IEEE INTERNATIONAL SYMPOSIUM ON PERFORMANCE ANALYSIS OF SYSTEMS AND SOFTWARE (ISPASS) AB - Many scientific applications (e.g., molecular dynamics, climate modeling and astrophysical simulations) rely on floating-point arithmetic. Due to its approximate nature, the use of floating-point arithmetic can lead to inaccuracy and reproducibility issues, which can be particularly significant for long running applications. Indeed, previous work has shown that 64- bit IEEE floating-point arithmetic can be insufficient for many algorithms and applications, such as ill-conditioned linear systems, large summations, long-time or large-scale physical simulations, and experimental mathematics applications. To overcome these issues, existing work has proposed high-precision floating-point libraries (e.g., the GNU multiple precision arithmetic library), but these libraries come at the cost of significant execution time. In this work, we propose an auto-tuner for applications requiring high-precision floating-point arithmetic to deliver a prescribed level of accuracy. Our auto-tuner uses compiler analysis to discriminate operations and variables that require high-precision from those that can be handled using standard IEEE 64-bit floating-point arithmetic, and it generates a mixed precision program that trades off performance and accuracy by selectively using different precisions for different variables and operations. In particular, our auto-tuner leverages loop and data dependences analysis to quickly identify precision-sensitive variables and operations and provide results that are robust to different input datasets. We test our auto-tuner on a mix of applications with different computational patterns. DA - 2020/// PY - 2020/// DO - 10.1109/ISPASS48437.2020.00048 SP - 285-295 KW - autotuner KW - mixed-precision KW - floating-point ER - TY - JOUR TI - A Stackelberg Security Investment Game for Voltage Stability of Power Systems AU - An, Lu AU - Chakrabortty, Aranya AU - Duel-Hallen, Alexandra T2 - 2020 59th IEEE Conference on Decision and Control (CDC) AB - We formulate a Stackelberg game between an attacker and a defender of a power system. The attacker attempts to alter the load setpoints of the power system covertly and intelligently, so that the voltage stability margin of the grid is reduced, driving the entire system towards a voltage collapse. The defender, or the system operator, aims to compensate for this reduction by retuning the reactive power injection to the grid by switching on control devices, such as a bank of shunt capacitors. A modified Backward Induction method is proposed to find a cost-based Stackelberg equilibrium (CBSE) of the game, which saves the players' costs while providing the optimal allocation of both players' investment resources under budget and covertness constraints. We analyze the proposed game extensively for the IEEE 9-bus power system model and present an example of its performance for the IEEE 39-bus power system model. It is demonstrated that the defender is able to maintain system stability unless its security budget is much lower than the attacker's budget. DA - 2020/// PY - 2020/// DO - 10.1109/cdc42340.2020.9304301 SP - 3359–3364, UR - http://dx.doi.org/10.1109/cdc42340.2020.9304301 ER - TY - JOUR TI - The Revival of Compound Semiconductors and How They Will Change the World in a 5G/6G Era T2 - ECS Transactions AB - The world is more than ever relying on connectivity in our daily life as well as our professional life. With 5G being rolled out, the industry is looking already at the next generation of mobile communication to bring even higher speeds and more connections than previous generations. But with 5G we are at an inflection point where it is not only about higher data rates and more connections, but about connecting different kind of devices and the new ways humans and machines interact with each other. The higher frequencies, low latency and reliability requirements will put a lot of strain on the technologies to enable this. While CMOS is the preferred vehicle, to fulfill these demands compound semiconductors like GaN and InP might be the better options for particular functions of the radio architecture. This paper will address the progress toward upscaling these materials to a Si platform and to make them CMOS and 3D compatible to enable the final heterogeneous systems that will be needed for 5G and beyond. DA - 2020/// PY - 2020/// DO - 10.1149/09805.0015ECST UR - https://publons.com/publon/43689205/ ER - TY - CONF TI - From 5G to 6G: will compound semiconductors make the difference? AB - In this work, we will address the opportunities of a hybrid III-V/CMOS technology for next generation wireless communication, beyond 5G, moving to operating frequencies above 100GHz. Challenges related to III-V upscaling and CMOS co-integration using 3D technologies will be discussed. C2 - 2020/// C3 - IEEE International Conference on Solid-State and Integrated Circuit Technology (ICSICT) DA - 2020/// DO - 10.1109/ICSICT49897.2020.9278253 UR - https://publons.com/publon/43689215/ ER - TY - CONF TI - Towards Wearable Electrochemical Lactate Sensing using Osmotic-Capillary Microfluidic Pumping AB - Sweat analysis has received significant attention recently because collection of sweat is minimally-invasive, and it contains a panel of physiologically relevant biomarkers. While there is a significant progress in engineering sensor systems for sweat analysis, a few major challenges remain unaddressed, e.g. contamination due to skin surface, old sweat mixing with new sweat, loss of sweat due to evaporation, and dilution of analytes on excessive sweating. To address some of these challenges, we present a wearable biosensor patch for biofluid extraction, sampling, and quantitative sensing. The wearable biosensor patch consists of (1) a hydrogel and paper-based microfluidic device for combined osmotic and capillary pumping of sweat coupled with (2) screen-printed electrodes for analysis of lactate concentration in sweat. In this report, we present our benchtop characterization of the proposed device towards the development of a continuous and wearable lactate monitoring system. This wearable biosensor patch advances the continuous, non-invasive monitoring of human biochemistry at low sweat rates. C2 - 2020/1/13/ C3 - 2019 IEEE SENSORS DA - 2020/1/13/ DO - 10.1109/sensors43011.2019.8956651 UR - http://dx.doi.org/10.1109/sensors43011.2019.8956651 ER - TY - JOUR TI - Principles of long-term fluids handling in paper-based wearables with capillary-evaporative transport. T2 - Biomicrofluidics AB - We construct and investigate paper-based microfluidic devices, which model long-term fluid harvesting, transport, sensing, and analysis in new wearables for sweat analysis. Such devices can continuously wick fluid mimicking sweat and dispose of it on evaporation pads. We characterize and analyze how the action of capillarity and evaporation can cooperatively be used to transport and process sweat mimics containing dissolved salts and model analytes. The results point out that non-invasive osmotic extraction combined with paper microfluidics and evaporative disposal can enable sweat collection and monitoring for durations longer than 10 days. We model the fluid flow in the new capillary–evaporative devices and identify the parameters enabling their long-term operation. We show that the transport rates are sufficiently large to handle natural sweat rates, while we envision that such handling can be interfaced with osmotic harvesting of sweat, a concept that we demonstrated recently. Finally, we illustrate that the salt film deposited at the evaporation pad would eventually lead to cessation of the process but at the same time will preserve a record of analytes that may be used for long-term biomarker monitoring in sweat. These principles can be implemented in future platforms for wearable skin-interfacing assays or electronic biomarker monitors. DA - 2020/5/1/ PY - 2020/5/1/ DO - 10.1063/5.0010417 UR - https://doi.org/10.1063/5.0010417 ER - TY - JOUR TI - Holistically-Attracted Wireframe Parsing AU - Xue, Nan AU - Wu, Tianfu AU - Bai, Song AU - Wang, Fudong AU - Xia, Gui-Song AU - Zhang, Liangpei AU - Torr, Philip H. S. T2 - 2020 IEEE/CVF CONFERENCE ON COMPUTER VISION AND PATTERN RECOGNITION (CVPR) AB - This paper presents a fast and parsimonious parsing method to accurately and robustly detect a vectorized wireframe in an input image with a single forward pass. The proposed method is end-to-end trainable, consisting of three components: (i) line segment and junction proposal generation, (ii) line segment and junction matching, and (iii) line segment and junction verification. For computing line segment proposals, a novel exact dual representation is proposed which exploits a parsimonious geometric reparameterization for line segments and forms a holistic 4-dimensional attraction field map for an input image. Junctions can be treated as the “basins” in the attraction field. The proposed method is thus called Holistically-Attracted Wireframe Parser (HAWP). In experiments, the proposed method is tested on two benchmarks, the Wireframe dataset [14] and the YorkUrban dataset [8]. On both benchmarks, it obtains state-of-the-art performance in terms of accuracy and efficiency. For example, on the Wireframe dataset, compared to the previous state-of-the-art method L-CNN [36], it improves the challenging mean structural average precision (msAP) by a large margin (2.8% absolute improvements), and achieves 29.5 FPS on a single GPU (89% relative improvement). A systematic ablation study is performed to further justify the proposed method. DA - 2020/// PY - 2020/// DO - 10.1109/CVPR42600.2020.00286 SP - 2785-2794 SN - 1063-6919 ER - TY - JOUR TI - Hardware-Based Domain Virtualization for Intra-Process Isolation of Persistent Memory Objects AU - Xu, Yuanchao AU - Ye, ChenCheng AU - Solihin, Yan AU - Shen, Xipeng T2 - 2020 ACM/IEEE 47TH ANNUAL INTERNATIONAL SYMPOSIUM ON COMPUTER ARCHITECTURE (ISCA 2020) AB - Persistent memory has appealing properties in serving as main memory. While file access is protected by system calls, an attached persistent memory object (PMO) is one load/store away from accidental (or malicious) reads or writes, which may arise from use of just one buggy library. The recent progress in intra-process isolation could potentially protect PMO by enabling a process to partition sensitive data and code into isolated components. However, the existing intra-process isolations (e.g., Intel MPK) support isolation of only up to 16 domains, forming a major barrier for PMO protections. Although there is some recent effort trying to virtualize MPK to circumvent the limit, it suffers large overhead. This paper presents two novel architecture supports, which provide 11 - 52 × higher efficiency while offering the first known domain-based protection for PMOs. DA - 2020/// PY - 2020/// DO - 10.1109/ISCA45697.2020.00062 SP - 680-692 SN - 0884-7495 KW - Persistent Memory Objects KW - Memory Protection Keys KW - Intra-process Isolation ER - TY - JOUR TI - CTLE Adaptation Using Deep Learning in High-speed SerDes Link AU - Li, Bowen AU - Jiao, Brandon AU - Chou, Chih-Hsun AU - Mayder, Romi AU - Franzon, Paul T2 - 2020 IEEE 70TH ELECTRONIC COMPONENTS AND TECHNOLOGY CONFERENCE (ECTC 2020) AB - To speed up a serial link simulation, it is critical to model the Serializer/Deserializer (SerDes) circuit behavior accurately. In this research, we focus on building a model for high-speed SerDes receiver CTLE adaptation behavior, which has a fast simulation speed and high-precision prediction. The proposed modeling method doesn't need any substantial domain knowledge. Deep neural networks model will be used to mimic the behavior of the CTLE adaptation process in the receiver. The proposed modeling method shows high correlations with the CTLE adaptation codes. DA - 2020/// PY - 2020/// DO - 10.1109/ECTC32862.2020.00155 SP - 952-955 SN - 2377-5726 KW - receiver KW - CTLE KW - adaptation KW - deep neural networks KW - high- correlation KW - fast ER - TY - JOUR TI - Slipstream Processors Revisited: Exploiting Branch Sets AU - Srinivasan, Vinesh AU - Chowdhury, Rangeen Basu Roy AU - Rotenberg, Eric T2 - 2020 ACM/IEEE 47TH ANNUAL INTERNATIONAL SYMPOSIUM ON COMPUTER ARCHITECTURE (ISCA 2020) AB - Delinquent branches and loads remain key performance limiters in some applications. One approach to mitigate them is pre-execution. Broadly, there are two classes of pre-execution: one class repeatedly forks small helper threads, each targeting an individual dynamic instance of a delinquent branch or load; the other class begins with two redundant threads in a leader-follower arrangement, and speculatively reduces the leading thread. The objective of this paper is to design a new pre-execution microarchitecture that meets four criteria: (i) retains the simpler coordination of a leader-follower microarchitecture, (ii) is fully automated with just hardware, (iii) targets both branches and loads, (iv) and is effective. We review prior preexecution proposals and show that none of them meet all four criteria. We develop Slipstream 2.0 to meet all four criteria. The key innovation in the space of leader-follower architectures is to remove the forward control-flow slices of delinquent branches and loads, from the leading thread. This innovation overcomes key limitations in the only other hardware-only leader-follower prior works: Slipstream and Dual Core Execution (DCE). Slipstream removes backward slices of confident branches to pre-execute unconfident branches, which is ineffective in phases dominated by unconfident branches when branch pre-execution is most needed. DCE is very effective at tolerating cache-missed loads, unless their dependent branches are mispredicted. Removing forward control-flow slices of delinquent branches and delinquent loads enables two firsts, respectively: (1) leader-follower-style branch pre-execution without relying on confident instruction removal, and (2) tolerance of cache-missed loads that feed mispredicted branches. For SPEC 2006/2017 SimPoints wherein Slipstream 2.0 is auto-enabled, it achieves geomean speedups of 67%, 60%, and 12%, over baseline (one core), Slipstream, and DCE. DA - 2020/// PY - 2020/// DO - 10.1109/ISCA45697.2020.00020 SP - 105-117 SN - 0884-7495 KW - branch prediction KW - prefetching KW - hard-to-predict branch KW - delinquent load KW - pre-execution KW - helper threads KW - control independence ER - TY - JOUR TI - Code-Modulated Embedded Test and Calibration of Phased-Array Transceivers AU - Hong, Zhangjie AU - Chauhan, Vikas AU - Schonherr, Simon AU - Floyd, Brian A. T2 - IEEE Transactions on Microwave Theory and Techniques AB - We present improved methods for built-in test and calibration of phased arrays in free-space using a code-modulated embedded test (CoMET). Our approach employs the Cartesian modulation of test signals within each element using existing phase shifters, the combination of these signals into a code-multiplexed response, creation of code-modulated element-to-element “interference products” using a built-in power detector, demodulation of correlations from the digitized interference response, and parallel in situ extraction of amplitude and phase per element using an equation solver. In this article, we review CoMET's methodology and then analyze the impact of noise within the system. To improve CoMET accuracy, a reference-element methodology is introduced, where all measurements are referred to as one element in the array whose phase is held constant. This is compared with another method in which the modulation axes are rotated to allow accurate extraction of phase near the original 0°/90°/180°/270° axes. Our techniques are demonstrated for both receive and transmit modes using an eight-element 8-16-GHz phased-array packaged and assembled together with patch antennas. Compared with network analyzer measurements, CoMET-extracted gain and phase using the reference-element method are accurate to within 0.4 dB and 2°-3° for free-space measurements, respectively. CoMET is then used within a calibration loop to equalize elemental gain and achieve a 7-bit phase resolution. In free space, the maximum gain and phase offsets between active antenna elements are reduced from 3.5 dB and 20°-90° to 1.1 dB and 0°, respectively. Calibrated beam patterns show significant improvement with peak-to-null ratios of >30 dB. DA - 2020/// PY - 2020/// DO - 10.1109/tmtt.2020.3041022 SP - 1-1 KW - Correlation KW - Calibration KW - Phased arrays KW - Phase measurement KW - Built-in self-test KW - Antenna measurements KW - Antenna arrays KW - Built-in self-test (BIST) KW - calibration KW - code modulation KW - interferometry KW - millimeter wave (mmWave) KW - phased arrays ER - TY - JOUR TI - A Trimodal Wireless Implantable Neural Interface System-on-Chip AU - Jia, Yaoyao AU - Guler, Ulkuhan AU - Lai, Yen-Pang AU - Gong, Yan AU - Weber, Arthur AU - Li, Wen AU - Ghovanloo, Maysam T2 - IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS AB - A wireless and battery-less trimodal neural interface system-on-chip (SoC), capable of 16-ch neural recording, 8-ch electrical stimulation, and 16-ch optical stimulation, all integrated on a 5 × 3 mm2 chip fabricated in 0.35-μm standard CMOS process. The trimodal SoC is designed to be inductively powered and communicated. The downlink data telemetry utilizes on-off keying pulse-position modulation (OOK-PPM) of the power carrier to deliver configuration and control commands at 50 kbps. The analog front-end (AFE) provides adjustable mid-band gain of 55-70 dB, low/high cut-off frequencies of 1-100 Hz/10 kHz, and input-referred noise of 3.46 μVrms within 1 Hz-50 kHz band. AFE outputs of every two-channel are digitized by a 50 kS/s 10-bit SAR-ADC, and multiplexed together to form a 6.78 Mbps data stream to be sent out by OOK modulating a 434 MHz RF carrier through a power amplifier (PA) and 6 cm monopole antenna, which form the uplink data telemetry. Optical stimulation has a switched-capacitor based stimulation (SCS) architecture, which can sequentially charge four storage capacitor banks up to 4 V and discharge them in selected μLEDs at instantaneous current levels of up to 24.8 mA on demand. Electrical stimulation is supported by four independently driven stimulating sites at 5-bit controllable current levels in ±(25-775) μA range, while active/passive charge balancing circuits ensure safety. In vivo testing was conducted on four anesthetized rats to verify the functionality of the trimodal SoC. DA - 2020/12// PY - 2020/12// DO - 10.1109/TBCAS.2020.3037452 VL - 14 IS - 6 SP - 1207-1217 SN - 1940-9990 KW - Stimulated emission KW - Capacitors KW - Biomedical optical imaging KW - Neuromodulation KW - Electrical stimulation KW - Wireless communication KW - Optical switches KW - Charge balancing KW - switched-capacitor based stimulation KW - trimodal neural interface KW - optogenetics KW - wireless power and data transmission ER - TY - JOUR TI - Hierarchical Multi-timescale Framework For Operation of Dynamic Community Microgrid DA - 2020/11/19/ PY - 2020/11/19/ ER - TY - JOUR TI - A Load Switching Group based Feeder-level Microgrid Energy Management Algorithm for Service Restoration in Power Distribution System DA - 2020/11/17/ PY - 2020/11/17/ ER - TY - JOUR TI - MAGIC: Live imaging of cellular division in plant seedlings using lightsheet microscopy AU - Madison, Imani AU - Melvin, Charles AU - Buckner, Eli AU - Williams, Cranos AU - Sozzani, Rosangela AU - Long, Terri T2 - PLANT CELL BIOLOGY AB - Imaging technologies have been used to understand plant genetic and developmental processes, from the dynamics of gene expression to tissue and organ morphogenesis. Although the field has advanced incredibly in recent years, gaps remain in identifying fine and dynamic spatiotemporal intervals of target processes, such as changes to gene expression in response to abiotic stresses. Lightsheet microscopy is a valuable tool for such studies due to its ability to perform long-term imaging at fine intervals of time and at low photo-toxicity of live vertically oriented seedlings. In this chapter, we describe a detailed method for preparing and imaging Arabidopsis thaliana seedlings for lightsheet microscopy via a Multi-Sample Imaging Growth Chamber (MAGIC), which allows simultaneous imaging of at least four samples. This method opens new avenues for acquiring imaging data at a high temporal resolution, which can be eventually probed to identify key regulatory time points and any spatial dependencies of target developmental processes. DA - 2020/// PY - 2020/// DO - 10.1016/bs.mcb.2020.04.004 VL - 160 SP - 405-418 SN - 0091-679X ER - TY - JOUR TI - BioVision Tracker: A semi-automated image analysis software for spatiotemporal gene expression tracking in Arabidopsis thaliana AU - Buckner, Eli AU - Madison, Imani AU - Melvin, Charles AU - Long, Terri AU - Sozzani, Rosangela AU - Williams, Cranos T2 - PLANT CELL BIOLOGY AB - Fluorescence microscopy can produce large quantities of data that reveal the spatiotemporal behavior of gene expression at the cellular level in plants. Automated or semi-automated image analysis methods are required to extract data from these images. These data are helpful in revealing spatial and/or temporal-dependent processes that influence development in the meristematic region of plant roots. Tracking spatiotemporal gene expression in the meristem requires the processing of multiple microscopy imaging channels (one channel used to image root geometry which serves as a reference for relating locations within the root, and one or more channels used to image fluorescent gene expression signals). Many automated image analysis methods rely on the staining of cell walls with fluorescent dyes to capture cellular geometry and overall root geometry. However, in long time-course imaging experiments, dyes may fade which hinders spatial assessment in image analysis. Here, we describe a procedure for analyzing 3D microscopy images to track spatiotemporal gene expression signals using the MATLAB-based BioVision Tracker software. This software requires either a fluorescence image or a brightfield image to analyze root geometry and a fluorescence image to capture and track temporal changes in gene expression. DA - 2020/// PY - 2020/// DO - 10.1016/bs.mcb.2020.04.017 VL - 160 SP - 419-436 SN - 0091-679X ER - TY - JOUR TI - Heuristic approach for jointly optimising FeICIC and UAV locations in multi-tier LTE-advanced public safety HetNet AU - Kumbhar, Abhaykumar AU - Binol, Hamidullah AU - Singh, Simran AU - Guvenc, Ismail AU - Akkaya, Kemal T2 - IET COMMUNICATIONS AB - Unmanned aerial vehicles (UAVs) enabled networks can enhance wireless connectivity and support emerging services. However, this would require system-level understanding to modify and extend the existing terrestrial network infrastructure. In this study, the authors integrated UAVs as user equipment and base stations into an existing long term evolution (LTE)-Advanced heterogeneous network (HetNet) and provide system-level insights of this three-tier LTE-Advanced air-ground HetNet (AG-HetNet). The performance of AG-HetNet was evaluated through brute-force technique and heuristics algorithms in terms of the fifth percentile spectral efficiency (5pSE) and coverage probability. In particular, system-wide 5pSE and coverage probability were compared, when unmanned aerial base stations (UABSs) are deployed on a fixed hexagonal grid and when their locations are optimised using a genetic algorithm (GA) and elitist harmony search algorithm based on the genetic algorithm (eHSGA); while jointly optimising the inter-cell interference coordination (ICIC) and cell range expansion (CRE) network parameters for different ICIC techniques. The simulation results show that the heuristic algorithms (GA and eHSGA) outperform the brute-force technique and achieve better peak values of coverage probability and 5pSE. Simulation results also show that a trade-off exists between peak values and computation time when using heuristic algorithms. Furthermore, the three-tier hierarchical structuring of reduced power subframes further-enhanced ICIC (FeICIC) defined in 3GPP Rel-11 provides considerably better 5pSE and coverage probability than the 3GPP Rel-10 with almost blank subframes eICIC. They also investigated the network performance for different practical deployment heights of UABS and they found low-altitude UABSs to perform sparsely better than medium-altitude UABSs. DA - 2020/12/15/ PY - 2020/12/15/ DO - 10.1049/iet-com.2019.1315 VL - 14 IS - 20 SP - 3585-3598 SN - 1751-8636 KW - Long Term Evolution KW - 3G mobile communication KW - genetic algorithms KW - autonomous aerial vehicles KW - intercell interference KW - array signal processing KW - optimisation KW - search problems KW - probability KW - elitist harmony search algorithm KW - genetic algorithm KW - CRE network parameters KW - ICIC techniques KW - Long Term Evolution-Advanced heterogeneous network KW - terrestrial network infrastructure KW - further-enhanced ICIC KW - joint optimisation KW - three-dimensional beamforming KW - fixed hexagonal grid KW - eHSGA KW - UABS KW - GA KW - unmanned aerial base stations KW - system-wide 5pSE KW - fifth percentile spectral efficiency KW - brute-force technique KW - intercell interference coordination KW - AG-HetNet KW - three-tier LTE-Advanced air-ground HetNet KW - user equipment KW - system-level understanding KW - emerging services KW - wireless connectivity KW - UAV-enabled communications KW - unmanned aerial vehicles KW - multitier LTE-advanced public safety HetNet KW - UAV locations KW - heuristic approach KW - network performance KW - 3GPP Rel-11 KW - FeICIC KW - three-tier hierarchical structuring KW - heuristic algorithms KW - coverage probability KW - peak values ER - TY - JOUR TI - Facile Approach to Fabricating Stretchable Organic Transistors with Laser-Patterned Ag Nanowire Electrodes AU - Song, Runqiao AU - Yao, Shanshan AU - Liu, Yuxuan AU - Wang, Hongyu AU - Dong, Jingyan AU - Zhu, Yong AU - Brendan T. O'Connor, T2 - ACS APPLIED MATERIALS & INTERFACES AB - Stretchable electronics are poised to revolutionize personal healthcare and robotics, where they enable distributed and conformal sensors. Transistors are fundamental building blocks of electronics, and there is a need to produce stretchable transistors using low-cost and scalable fabrication techniques. Here, we introduce a facile fabrication approach using laser patterning and transfer printing to achieve high-performance, solution-processed intrinsically stretchable organic thin-film transistors (OTFTs). The device consists of Ag nanowire (NW) electrodes, where the source and drain electrodes are patterned using laser ablation. The Ag NWs are then partially embedded in a poly(dimethylsiloxane) (PDMS) matrix. The electrodes are combined with a PDMS dielectric and polymer semiconductor, where the layers are individually transfer printed to complete the OTFT. Two polymer semiconductors, DPP-DTT and DPP-4T, are considered and show stable operation under the cyclic strain of 20 and 40%, respectively. The OTFTs maintain electrical performance by adopting a buckled structure after the first stretch-release cycle. The conformability and stretchability of the OTFT is also demonstrated by operating the transistor while adhered to a finger being flexed. The ability to pattern highly conductive Ag NW networks using laser ablation to pattern electrodes as well as interconnects provides a simple strategy to produce complex stretchable OTFT-based circuits. DA - 2020/11/11/ PY - 2020/11/11/ DO - 10.1021/acsami.0c15339 VL - 12 IS - 45 SP - 50675-50683 SN - 1944-8252 KW - stretchable electronics KW - Ag nanowires KW - laser patterning KW - organic electronics KW - organic thin-film transistors ER - TY - JOUR TI - From Federated to Fog Learning: Distributed Machine Learning over Heterogeneous Wireless Networks AU - Hosseinalipour, Seyyedali AU - Brinton, Christopher G. AU - Aggarwal, Vaneet AU - Dai, Huaiyu AU - Chiang, Mung T2 - IEEE COMMUNICATIONS MAGAZINE AB - Machine learning (ML) tasks are becoming ubiquitous in today's network applications. Federated learning has emerged recently as a technique for training ML models at the network edge by leveraging processing capabilities across the nodes that collect the data. There are several challenges with employing conventional federated learning in contemporary networks, due to the significant heterogeneity in compute and communication capabilities that exist across devices. To address this, we advocate a new learning paradigm called fog learning, which will intelligently distribute ML model training across the continuum of nodes from edge devices to cloud servers. Fog learning enhances federated learning along three major dimensions: network, heterogeneity, and proximity. It considers a multi-layer hybrid learning framework consisting of heterogeneous devices with various proximities. It accounts for the topology structures of the local networks among the heterogeneous nodes at each network layer, orchestrating them for collaborative/cooperative learning through device-to-device communications. This migrates from star network topologies used for parameter transfers in federated learning to more distributed topologies at scale. We discuss several open research directions toward realizing fog learning. DA - 2020/12// PY - 2020/12// DO - 10.1109/MCOM.001.2000410 VL - 58 IS - 12 SP - 41-47 SN - 1558-1896 KW - Training KW - Network topology KW - Computational modeling KW - Wireless networks KW - Collaborative work KW - Topology KW - Device-to-device communication ER - TY - JOUR TI - Enhancement of Diffusion, Densification and Solid-State Reactions in Dielectric Materials Due to Interfacial Interaction of Microwave Radiation: Theory and Experiment AU - Malhotra, Abhishek AU - Hosseini, Mahshid AU - Zaferani, Sadeq Hooshmand AU - Hall, Michael AU - Vashaee, Daryoosh T2 - ACS APPLIED MATERIALS & INTERFACES AB - A detailed theoretical model and experimental study are presented that formulate and prove the existence of a robust ponderomotive force (PMF) near the interfaces in a granular dielectric material under microwave radiation. The model calculations show that the net direction of the PMF is pore angle-dependent. For most of the pore angles, the net force is towards the interface creating a mass transport that fills the interfacial pores and facilitates densification. For small ranges of angles, near 180o and 360o, PMF drives the ions in the reverse direction and depletes the pores. However, the net force for such ranges of angles is small. The PMF also enhances the diffusion of the mobile ionic species and, consequently, accelerates the solid-state reaction by increasing the collision probability. The proof-of-concept experiments show that a mixture of elemental powders can diffuse, react, and form dense materials when radiated by the microwave in just a few minutes. Such characteristics, together with field-induced decrystallization, offer a novel and simple approach for the synthesis of nanostructured compounds, which can have practical implications in ceramic technologies and thermoelectric materials. DA - 2020/11/11/ PY - 2020/11/11/ DO - 10.1021/acsami.0c09719 VL - 12 IS - 45 SP - 50941-50952 SN - 1944-8252 KW - interfacial ponderomotive force KW - electromagnetic wave interaction with materials KW - microwave sintering KW - solid-state reaction KW - ceramics KW - thermoelectrics ER - TY - JOUR TI - Enhancing the morphological segmentation of microscopic fossils through Localized Topology-Aware Edge Detection AU - Ge, Qian AU - Richmond, Turner AU - Zhong, Boxuan AU - Marchitto, Thomas M. AU - Lobaton, Edgar T2 - AUTONOMOUS ROBOTS DA - 2020/// PY - 2020/// DO - 10.1007/s10514-020-09950-9 VL - 11 KW - Edge detection KW - Topological structure KW - Morphological segmentation ER - TY - JOUR TI - Optical bistability and self-opacity in magnetically doped monolayer transition metal dichalcogenides AU - Regan, Malcolm J. AU - Semenov, Yuriy G. AU - Kim, Ki Wook T2 - PHYSICAL REVIEW B AB - Magneto-optical control of optical absorption spectra is theoretically investigated in two-dimensional (2D) dilute magnetic semiconductors such as monolayer transition metal dichalcogenides (TMDs) doped with magnetic ions. The underlying mechanism relies on efficient spin transfer between spin-polarized photoexcited carriers and localized magnetic ions via exchange scattering, and subsequent shifts in the electronic band structure induced by the resulting time-reversal symmetry breaking. A self-consistent model based on a rate equation is developed to analyze dynamical polarization of itinerant carrier spins and localized magnetic moments under circularly polarized optical excitation and the corresponding band modifications. The results illustrate that nonlinear effects such as optical bistability and self-opacity can indeed be achieved efficiently for a range of excitation power and frequency. In particular, the addition of magnetic dopants is shown to reduce the optical power required for the necessary band shifts by four orders of magnitude compared to that via the optical Stark effect in a nonmagnetic counterpart. Further investigation in a multidimensional parameter space elucidates the conditions for practical realization of the desired nonlinear effects in 2D TMD monolayers. DA - 2020/12/22/ PY - 2020/12/22/ DO - 10.1103/PhysRevB.102.214426 VL - 102 IS - 21 SP - SN - 2469-9969 ER - TY - JOUR TI - Passive Radar at the Roadside Unit to Configure Millimeter Wave Vehicle-to-Infrastructure Links AU - Ali, Anum AU - Gonzalez-Prelcic, Nuria AU - Ghosh, Amitava T2 - IEEE Transactions on Vehicular Technology AB - Millimeter wave (mmWave) vehicular channels are highly dynamic, and the communication link needs to be reconfigured frequently. In this work, we propose to use a passive radar receiver at the roadside unit to reduce the training overhead of establishing an mmWave communication link. Specifically, the passive radar will tap the transmissions from the automotive radars of the vehicles on the road. The spatial covariance of the received radar signals will be estimated and used to establish the communication link. We propose a simplified radar receiver that does not require the transmitted waveform as a reference. To leverage the radar information for beamforming, the radar azimuth power spectrum (APS) and the communication APS should be similar. We outline a radar covariance correction strategy to increase the similarity between the radar and communication APS. We also propose a metric to compare the similarity of the radar and communication APS that has a connection with the achievable rate. We present simulation results based on ray-tracing data. The results show that: (i) covariance correction improves the similarity of radar and communication APS, and (ii) the radar-assisted strategy significantly reduces the training overhead, being particularly useful in non-line-of-sight scenarios. DA - 2020/12// PY - 2020/12// DO - 10.1109/TVT.2020.3027636 VL - 69 IS - 12 SP - 14903-14917 UR - https://doi.org/10.1109/TVT.2020.3027636 KW - Passive radar KW - Antenna arrays KW - Radar antennas KW - Measurement KW - Receivers KW - Wireless communication KW - Out-of-band information KW - millimeter wave communications KW - FMCW radar KW - radar-aided communication KW - beyond 5G ER - TY - JOUR TI - Health and economic impacts of air pollution induced by weather extremes over the continental US AU - Zhang, Yang AU - Yang, Peilin AU - Gao, Yang AU - Leung, Ruby L. AU - Bell, Michelle L. T2 - ENVIRONMENT INTERNATIONAL AB - Extreme weather events may enhance ozone (O3) and fine particulate matter (PM2.5) pollution, causing additional adverse health effects. This work aims to evaluate the health and associated economic impacts of changes in air quality induced by heat wave, stagnation, and compound extremes under the Representative Concentration Pathways (RCP) 4.5 and 8.5 climate scenarios. The Environmental Benefits Mapping and Analysis Program-Community Edition is applied to estimate health and related economic impacts of changes in surface O3 and PM2.5 levels due to heat wave, stagnation, and compound extremes over the continental U.S. during past (i.e., 2001–2010) and future (i.e., 2046–2055) decades under the two RCP scenarios. Under the past and future decades, the weather extremes-induced concentration increases may lead to several tens to hundreds O3-related deaths and several hundreds to over ten thousands PM2.5-related deaths annually. High mortalities and morbidities are estimated for populated urban areas with strong spatial heterogeneities. The estimated annual costs for these O3 and PM2.5 related health outcomes are $5.5–12.5 and $48.6–140.7 billion U.S. dollar for mortalities, and $8.9–97.8 and $19.5–112.5 million for morbidities, respectively. Of the extreme events, the estimated O3– and PM2.5–related mortality and morbidity attributed to stagnation are the highest, followed by heat wave or compound extremes. Large increases in heat wave and compound extreme events in the future decade dominate changes in mortality during these two extreme events, whereas population growth dominates changes in mortality during stagnation that is projected to occur less frequently. Projected reductions of anthropogenic emissions under both RCP scenarios compensate for the increased mortality due to increased occurrence for heat wave and compound extremes in the future. These results suggest a need to further reduce air pollutant emissions during weather extremes to minimize the adverse impacts of weather extremes on air quality and human health. DA - 2020/10// PY - 2020/10// DO - 10.1016/j.envint.2020.105921 VL - 143 SP - SN - 1873-6750 KW - Weather extremes KW - O-3 KW - PM2.5 KW - Mortality KW - Morbidity KW - Continental US ER - TY - JOUR TI - A Systematic Literature Review of Animal-Assisted Interventions in Oncology (Part II): Theoretical Mechanisms and Frameworks AU - Holder, Timothy R. N. AU - Gruen, Margaret E. AU - Roberts, David L. AU - Somers, Tamara AU - Bozkurt, Alper T2 - INTEGRATIVE CANCER THERAPIES AB - Animal-assisted interventions (AAIs) can improve patients’ quality of life as complementary medical treatments. Part I of this 2-paper systematic review focused on the methods and results of cancer-related AAIs; Part II discusses the theories of the field’s investigators. Researchers cite animal personality, physical touch, physical movement, distraction, and increased human interaction as sources of observed positive outcomes. These mechanisms then group under theoretical frameworks such as the social support hypothesis or the human-animal bond concept to fully explain AAI in oncology. The cognitive activation theory of stress, the science of unitary human beings, and the self-object hypothesis are additional frameworks mentioned by some researchers. We also discuss concepts of neurobiological transduction connecting mechanisms to AAI benefits. Future researchers should base study design on theories with testable hypotheses and use consistent terminology to report results. This review aids progress toward a unified theoretical framework and toward more holistic cancer treatments. DA - 2020/7// PY - 2020/7// DO - 10.1177/1534735420943269 VL - 19 SP - SN - 1552-695X KW - animal-assisted interventions KW - animal-assisted activities KW - animal-assisted therapy KW - oncology KW - cancer KW - human-animal bond KW - mechanisms KW - theoretical frameworks ER - TY - JOUR TI - Phonon-boundary scattering and thermal transport in AlxGa1-xN: Effect of layer thickness AU - Tran, Dat Q. AU - Delgado-Carrasco, Rosalia AU - Muth, John F. AU - Paskova, Tania AU - Nawaz, Muhammad AU - Darakchieva, Vanya AU - Paskov, Plamen P. T2 - APPLIED PHYSICS LETTERS AB - Thermal conductivity of AlxGa1−xN layers with 0≤x≤0.96 and variable thicknesses is systematically studied by combined thermoreflectance measurements and a modified Callaway model. We find a reduction in the thermal conductivity of AlxGa1−xN by more than one order of magnitude compared to that of GaN, which indicates a strong effect of phonon-alloy scattering. It is shown that the short-mean free path phonons are strongly scattered, which leads to a major contribution of the long-mean free path phonons to the thermal conductivity. In thin layers, the long-mean free path phonons become efficiently scattered by the boundaries, resulting in a further decrease in the thermal conductivity. Also, an asymmetry of thermal conductivity as a function of Al content is experimentally observed and attributed to the mass difference between Ga and Al host atoms. DA - 2020/12/21/ PY - 2020/12/21/ DO - 10.1063/5.0031404 VL - 117 IS - 25 SP - SN - 1077-3118 ER - TY - JOUR TI - Wirelessly-Powered Cage Designs for Supporting Long-Term Experiments on Small Freely Behaving Animals in a Large Experimental Arena AU - Lee, Byunghun AU - Jia, Yaoyao T2 - ELECTRONICS AB - In modern implantable medical devices (IMDs), wireless power transmission (WPT) between inside and outside of the animal body is essential to power the IMD. Unlike conventional WPT, which transmits the wireless power only between fixed Tx and Rx coils, the wirelessly-powered cage system can wirelessly power the IMD implanted in a small animal subject while the animal freely moves inside the cage during the experiment. A few wirelessly-powered cage systems have been developed to either directly power the IMD or recharge batteries during the experiment. Since these systems adapted different power carrier frequencies, coil configurations, subject tracking techniques, and wireless powered area, it is important for designers to select suitable wirelessly-powered cage designs, considering the practical limitations in wirelessly powering the IMD, such as power transfer efficiency (PTE), power delivered to load (PDL), closed-loop power control (CLPC), scalability, spatial/angular misalignment, near-field data telemetry, and safety issues against various perturbations during the longitudinal animal experiment. In this article, we review the trend of state-of-the-art wirelessly-powered cage designs and practical considerations of relevant technologies for various IMD applications. DA - 2020/12// PY - 2020/12// DO - 10.3390/electronics9121999 VL - 9 IS - 12 SP - SN - 2079-9292 KW - wirelessly-powered cage KW - inductive power transmission KW - implantable medical device KW - animal experiment ER - TY - JOUR TI - In Vivo Evaluation of a Subcutaneously Injectable Implant with a Low-Power Photoplethysmography ASIC for Animal Monitoring AU - Valero-Sarmiento, Jose Manuel F. AU - Ahmmed, Parvez AU - Bozkurt, Alper T2 - SENSORS AB - Photoplethysmography is an extensively-used, portable, and noninvasive technique for measuring vital parameters such as heart rate, respiration rate, and blood pressure. The deployment of this technology in veterinary medicine has been hindered by the challenges in effective transmission of light presented by the thick layer of skin and fur of the animal. We propose an injectable capsule system to circumvent these limitations by accessing the subcutaneous tissue to enable reliable signal acquisition even with lower light brightness. In addition to the reduction of power usage, the injection of the capsule offers a less invasive alternative to surgical implantation. Our current prototype combines two application-specific integrated circuits (ASICs) with a microcontroller and interfaces with a commercial light emitting diode (LED) and photodetector pair. These ASICs implement a signal-conditioning analog front end circuit and a frequency-shift keying (FSK) transmitter respectively. The small footprint of the ASICs is the key in the integration of the complete system inside a 40-mm long glass tube with an inner diameter of 4 mm, which enables its injection using a custom syringe similar to the ones used with microchip implants for animal identification. The recorded data is transferred wirelessly to a computer for post-processing by means of the integrated FSK transmitter and a software-defined radio. Our optimized LED duty cycle of 0.4% at a sampling rate of 200 Hz minimizes the contribution of the LED driver (only 0.8 mW including the front-end circuitry) to the total power consumption of the system. This will allow longer recording periods between the charging cycles of the batteries, which is critical given the very limited space inside the capsule. In this work, we demonstrate the wireless operation of the injectable system with a human subject holding the sensor between the fingers and the in vivo functionality of the subcutaneous sensing on a pilot study performed on anesthetized rat subjects. DA - 2020/12// PY - 2020/12// DO - 10.3390/s20247335 VL - 20 IS - 24 SP - SN - 1424-8220 UR - https://doi.org/10.3390/s20247335 KW - injectable KW - photoplethysmography KW - biomedical electronics KW - biophotonics KW - encapsulation KW - implant KW - in vivo KW - biomedical telemetry KW - software radio ER - TY - JOUR TI - A Lightweight Memory Access Pattern Obfuscation Framework for NVM AU - Che, Yuezhi AU - Yang, Yuanzhou AU - Awad, Amro AU - Wang, Rujia T2 - IEEE COMPUTER ARCHITECTURE LETTERS AB - Emerging Non-Volatile Memories (NVMs) are entering the mainstream market. With attractive performance, high density, and near-zero idle power, emerging NVMs are promising contenders to build future memory systems. On the other hand, their limited write endurance (106 to 108 write cycles) and enabling data remanence attacks remain as main challenges that could hinder the wide adoption of NVMs in many sectors. With the limited write-endurance of NVMs, implementing major security primitives, such as Oblivious RAM (ORAM) for memory access pattern obfuscation, become more challenging due to a massive extra-write operation demand, which will exacerbate the write endurance problem. Wear-leveling techniques aim at mitigating the endurance problem of NVM by shuffling locations and continuously changing the mappings of memory addresses to the actual memory cells. However, such wear-leveling techniques do not provide the access pattern obfuscation forsecurity. In this letter, we propose a lightweight memory access pattern obfuscation framework for NVM, called O-NVM, a novel design that achieves both wear-leveling and obfuscation with an appealing level of performance and security (obfuscation) guarantees. Our experimental results show that the NVM's lifetime can be improved by 4 - 125 X , and the randomness of address access patterns can achieve the passing rate of statistics tests over 99 percent. DA - 2020/// PY - 2020/// DO - 10.1109/LCA.2020.3041484 VL - 19 IS - 2 SP - 163-166 SN - 1556-6064 KW - Non-volatile memory (NVM) KW - main memory KW - memory obfuscation KW - wear-leveling ER - TY - JOUR TI - Beyond Regimes: China and India Compared. AU - Gilmartin, David T2 - JOURNAL OF ASIAN STUDIES AB - Beyond Regimes: China and India Compared. Edited by Prasenjit Duara and Elizabeth J. Perry. Cambridge, Mass.: Harvard University Asia Center, 2018. xvii, 341 pp. ISBN: 9780674987104 (paper). - Volume 79 Issue 4 DA - 2020/11// PY - 2020/11// DO - 10.1017/S0021911820002934 VL - 79 IS - 4 SP - 1076-1077 SN - 1752-0401 ER - TY - JOUR TI - The Physical Manifestation of Side Reactions in the Electrolyte of Lithium-Ion Batteries and Its Impact on the Terminal Voltage Response AU - Balagopal, Bharat AU - Chow, Mo-Yuen T2 - BATTERIES-BASEL AB - Batteries as a multi-disciplinary field have been analyzed from the electrical, material science and electrochemical engineering perspectives. The first principle-based four-dimensional degradation model (4DM) of the battery is used in the article to connect the interdisciplinary sciences that deal with batteries. The 4DM is utilized to identify the physical manifestation that electrolyte degradation has on the battery and the response observed in the terminal voltage. This paper relates the different kinds of side reactions in the electrolyte and the material properties affected due to these side reactions. It goes on to explain the impact the material property changes has on the electrochemical reactions in the battery. This paper discusses how these electrochemical reactions affect the voltage across the terminals of the battery. We determine the relationship the change in the terminal voltage has due to the change in the design properties of the electrolyte. We also determine the impact the changes in the electrolyte material property have on the terminal voltage. In this paper, the lithium ion concentration and the transference number of the electrolyte are analyzed and the impact of their degradation is studied. DA - 2020/12// PY - 2020/12// DO - 10.3390/batteries6040053 VL - 6 IS - 4 SP - SN - 2313-0105 KW - sensitivity KW - electrolyte KW - lithium ion battery KW - degradation KW - 4DM KW - terminal voltage KW - side reactions ER - TY - CHAP TI - Heterojunction Bipolar Transistors and Monolithically Integrated Photoreceivers Among Other Applications T2 - Women in Microelectronics AB - ​This book contains stories and insight to women engineers’ contributions and research through the golden age of microelectronics, starting from the invention of the transistor in 1947 to modern day video games; while discussing the challenges they overcame. PY - 2020/7/31/ DO - https://doi.org/10.1007/978-3-030-46377-9 ER - TY - BOOK TI - Women in Microelectronics DA - 2020/7/31/ PY - 2020/7/31/ UR - http://www.springer.com/ ER - TY - JOUR TI - Dual-Affinity Ratiometric Quenching (DARQ) Assay for the Quantification of Therapeutic Antibodies in CHO-S Cell Culture Fluids AU - Turner, Brendan L. AU - Kilgour, Katie M. AU - Stine, Sydney J. AU - Daniele, Michael AU - Menegatti, Stefano T2 - ANALYTICAL CHEMISTRY AB - More than 100 monoclonal antibodies (mAbs) are in industrial and clinical development to treat myriad diseases. Accurate quantification of mAbs in complex media, derived from industrial and patient samples, is vital to determine production efficiency or pharmacokinetic properties. To date, mAb quantification requires time and labor-intensive assays. Herein, we report a novel dual-affinity ratiometric quenching (DARQ) assay, which combines selective biorecognition and quenching of fluorescence signals for rapid and sensitive quantification of therapeutic monoclonal antibodies (mAbs). The reported assay relies on the affinity complexation of the target mAb by the corresponding antigens and Protein L (PrL, which targets the Fab region of the antibody), respectively, labeled with fluorescein and rhodamine. Within the affinity complex, the mAb acts as a scaffold framing the labeled affinity tags (PrL and antigen) in a molecular proximity that results in ratiometric quenching of their fluorescence emission. Notably, the decrease in fluorescence emission intensity is linearly dependent upon mAb concentration in solution. Control experiments conducted with one affinity tag only, two tags labeled with equal fluorophores, or two tags labeled with fluorophores of discrete absorbance and emission bands exhibited significantly reduced effect. The assay was evaluated in noncompetitive (pure mAb) and competitive conditions (mAb in a Chinese Hamster Ovary (CHO) cell culture harvest). The “DARQ” assay is highly reproducible (coefficient of variation ∼0.8–0.7%) and rapid (5 min), and its sensitivity (∼0.2–0.5 ng·mL–1), limit of detection (75–119 ng·mL–1), and dynamic range (300–1600 ng·mL–1) are independent of the presence of CHO host cell proteins. DA - 2020/12/15/ PY - 2020/12/15/ DO - 10.1021/acs.analchem.0c04269 VL - 92 IS - 24 SP - 16274-16283 SN - 1520-6882 ER - TY - JOUR TI - Multibeam Phased-Arrays Using Dual-Vector Distributed Beamforming: Architecture Overview and 28 GHz Transceiver Prototypes AU - Yeh, Yi-Shin AU - Floyd, Brian A. T2 - IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS I-REGULAR PAPERS AB - This article presents a dual-vector distributed beamformer architecture that employs a series-feed network and is capable of supporting up to four simultaneous beams. The multibeam array uses scalar functions within each front end to create Cartesian-weighted signals needed for phase shifting. A dual-vector series-feed network combines/distributes these signals for the receiver/transmitter whereas a global quadrature interpolator is used to create two conjugate beams. By using an interpolator on either end of the series feed, a total of four beams can be obtained. Among these four beams, a first beam can be controlled independently, a second beam is formed as an image of the first, a third beam is offset from the first based on the amount of phase shift within the series-feed structure, and a fourth beam is an image of the offset beam. In this work, the theory of operation of the series-feed DVDB is presented and then two different four-element 28 GHz DVDB transceiver array prototypes in 120 nm SiGe BiCMOS technology are described. One uses a hybrid coupler for global interpolation at radio frequency (RF) and the other uses quadrature mixers for global interpolation at baseband. Measurement results for the array employing passive interpolation at RF show excellent phase-shifting performance, including <; 1 dB root-mean-squared (RMS) gain error, <; 2 degree RMS phase error, 24% 3 dB bandwidth, with 16-18.6 dBm saturated output power in transmit mode and 4.9-7.3 dB noise figure in receive mode. Measurement results for the array employing mixer-based interpolation likewise show excellent phase-shifting performance with similar RMS gain and phase errors and slightly degraded overall RF performance. Comparing the two, we conclude that the DVDB with passive interpolation at RF is better suited for partitioned systems where beamformers and transceivers are realized on separate chips to support larger, scalable arrays. In contrast, the DVDB with mixer-based interpolation is better suited for integrated systems where beamformers and frequency translation functions must be integrated together. DA - 2020/12// PY - 2020/12// DO - 10.1109/TCSI.2020.3026624 VL - 67 IS - 12 SP - 5496-5509 SN - 1558-0806 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85097341095&partnerID=MN8TOARS KW - Array signal processing KW - Radio frequency KW - Transceivers KW - Interpolation KW - Phased arrays KW - Receivers KW - Mixers KW - Phased array KW - hybrid beamforming KW - transceiver KW - SiGe BiCMOS KW - fifth generation (5G) KW - 28 GHz KW - multibeam KW - phase shifter KW - millimeter-wave KW - series-feed KW - dual-vector distributed beamforming KW - integrated circuits KW - wideband ER - TY - JOUR TI - Sparsity-promoting optimal control of cyber-physical systems over shared communication networks AU - Negi, Nandini AU - Chakrabortty, Aranya T2 - AUTOMATICA AB - Recent years have seen several new directions in the design of sparse control of cyber–physical systems (CPSs) driven by the objective of reducing communication costs. One common assumption made in these designs is that the communication happens over a dedicated network. For many practical applications, however, communication must occur over shared networks, leading to two critical design challenges, namely — time-delays in the feedback and fair sharing of bandwidth among users. In this paper, we present a set of sparse H2 control designs under these two design constraints. An essential aspect of our design is that the delay itself can be a function of sparsity, which leads to an interesting pattern of trade-offs in the H2 performance. We present three distinct algorithms. The first algorithm preconditions the assignable bandwidth to the network and produces an initial guess for a stabilizing controller. This is followed by our second algorithm, which sparsifies this controller while simultaneously adapting the feedback delay and optimizing the H2 performance using alternating directions method of multipliers (ADMM). The third algorithm extends this approach to a multiple user scenario where an optimal number of communication links, whose total sum is fixed, is distributed fairly among users by minimizing the variance of their H2 performances. The problem is cast as a difference-of-convex (DC) program with mixed-integer linear program (MILP) constraints. We provide theorems to prove the convergence of these algorithms, followed by validation through numerical simulations. DA - 2020/12// PY - 2020/12// DO - 10.1016/j.automatica.2020.109217 VL - 122 SP - SN - 1873-2836 KW - Linear optimal control KW - Structural optimization KW - Time-delay systems KW - Delay analysis KW - Bandwidth allocation ER - TY - JOUR TI - Ultra-Wideband Air-to-Ground Propagation Channel Characterization in an Open Area AU - Khawaja, Wahab AU - Ozdemir, Ozgur AU - Erden, Fatih AU - Guvenc, Ismail AU - Matolak, David W. T2 - IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS AB - This paper studies the air-to-ground ultra-wideband channel through propagation measurements between 3.1 GHz to 4.8 GHz using unmanned-aerial-vehicles (UAVs). Different line-of-sight (LOS) and obstructed-LOS scenarios and two antenna orientations were used in the experiments. Multipath channel statistics for different propagation scenarios were obtained, and the Saleh-Valenzuela model was found to provide a good fit for the statistical channel model. An analytical path loss model based on antenna gains in the elevation plane is provided for unobstructed UAV hovering and moving (in a circular path) propagation scenarios. DA - 2020/12// PY - 2020/12// DO - 10.1109/TAES.2020.3003104 VL - 56 IS - 6 SP - 4533-4555 SN - 1557-9603 UR - https://doi.org/10.1109/TAES.2020.3003104 KW - Antenna measurements KW - Receiving antennas KW - Ultra wideband antennas KW - Antenna radiation patterns KW - Loss measurement KW - Area measurement KW - Air-to-ground  KW - (AG) KW - channel model KW - drone KW - multipath channel KW - path loss KW - propagation measurements KW - ultra-wideband  KW - (UWB) KW - unmanned-aerial-vehicle  KW - (UAV) ER - TY - JOUR TI - A Sinusoidal Current Control Strategy Based on Harmonic Voltage Injection for Harmonic Loss Reduction of PMSMs With Non-Sinusoidal Back-EMF AU - Kim, Heonyoung AU - Han, Yongsu AU - Lee, Kibok AU - Bhattacharya, Subhashish T2 - IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS AB - In permanent magnet synchronous machine design, a limited number of stator and rotor slots distorts the air-gap flux distribution and its effective length. It causes machine parameters to vary with the rotor position. The rotor flux linkage harmonics introduce nonsinusoidal back-EMF, which causes current harmonics when conventional PI current controller is adopted. Those machines suffer from high-frequency torque ripple due to air-gap flux harmonics in low-speed region. However, in high-speed region, where the torque ripple is filtered out by the mechanical system, the torque ripple may be disregarded. In this case, torque-ripple suppression methods and the associated harmonic current components generate losses. Therefore, a sinusoidal current control is required to reduce the undesired harmonic losses. In this manner, this article focuses on the sinusoidal current control strategy based on harmonic voltage injection, which requires knowledge of rotor magnet flux linkage harmonics. This article also proposes both off- and on-line schemes for the identification of rotor magnet flux linkage harmonics. These methods do not require any proprietary machine design details such as the shape of stator or rotor for finite element analysis. Commonly used PI plus resonant controller is also designed and its disadvantages in terms of speed-dependent gain and stability, in comparison to the proposed scheme, are highlighted. Finally, experimental results are presented to compare the proposed scheme with the conventional method at different operating conditions. DA - 2020/11// PY - 2020/11// DO - 10.1109/TIA.2020.3016210 VL - 56 IS - 6 SP - 7032-7043 SN - 1939-9367 UR - https://doi.org/10.1109/TIA.2020.3016210 KW - Harmonic analysis KW - Rotors KW - Power harmonic filters KW - Magnetic flux KW - Couplings KW - Saturation magnetization KW - Stator windings KW - Harmonic current losses reduction KW - harmonic rotor flux identification KW - harmonic voltage injection KW - nonsinusoidal back-EMF KW - nonsinusoidal machine current KW - permanent magnet synchronous machine (PMSM) KW - resonant controller (RC) ER - TY - JOUR TI - High-Level Synthesis of Number-Theoretic Transform: A Case Study for Future Cryptosystems AU - Ozcan, Erdem AU - Aysu, Aydin T2 - IEEE EMBEDDED SYSTEMS LETTERS AB - Compared to traditional hardware development methodologies, high-level synthesis (HLS) offers a faster time-to-market and lower design-cost at the expense of implementation efficiency. Although HLS tools are becoming popular in some applications, such as digital signal processing and neural network classification, their usability on cryptographic applications is largely unexplored. This feasibility is critical especially for cryptosystems that are under development, such as the next-generation public-key cryptosystems needed for quantum-resistance. This letter provides a thorough investigation of HLS on number theoretic transform (NTT)-the core arithmetic function of lattice-based quantum-resistant cryptosystems. We demonstrate a fast yet extensive design space exploration of NTT through the Vivado HLS tool, analyze the shortcomings/challenges of optimized configurations, and quantitatively compare the results to software-based and hand-coded hardware designs. DA - 2020/12// PY - 2020/12// DO - 10.1109/LES.2019.2960457 VL - 12 IS - 4 SP - 133-136 SN - 1943-0671 KW - Field programmable gate array (FPGA) KW - hardware design KW - high-level synthesis (HLS) KW - lattice-based cryptography KW - post-quantum cryptography ER - TY - JOUR TI - Multiple ray received power modelling for mmWave indoor and outdoor scenarios AU - Khawaja, Wahab AU - Ozdemir, Ozgur AU - Erden, Fatih AU - Ozturk, Ender AU - Guvenc, Ismail T2 - IET MICROWAVES ANTENNAS & PROPAGATION AB - Millimetre-wave (mmWave) frequency bands are expected to be used for future fifth generation networks due to the availability of a large unused spectrum. However, the attenuation at mmWave frequencies is high. To resolve this issue, the utilisation of high gain antennas and beamforming mechanisms are widely investigated in the literature. In this work, the authors considered mmWave end-to-end propagation modelled by individual ray sources and explored the effects of the number of rays in the model and radiation patterns of the deployed antennas on the received power. It is shown that taking the dominant two rays is sufficient to model the channel for outdoor open areas as opposed to the indoor corridor which needs five dominant rays to have a good fit for the measurement and simulation results. It is observed that the radiation pattern of the antenna affects the slope of the path loss. Multi-path components increase the received power, thus, for indoor corridor scenarios, path loss according to the link distance is smaller for lower gain antennas due to increased reception of reflected components. For an outdoor open area, the slope of the path loss is found to be very close to that of the free space. DA - 2020/11/25/ PY - 2020/11/25/ DO - 10.1049/iet-map.2020.0046 VL - 14 IS - 14 SP - 1825-1836 SN - 1751-8733 UR - https://doi.org/10.1049/iet-map.2020.0046 KW - indoor radio KW - array signal processing KW - ray tracing KW - millimetre wave propagation KW - directive antennas KW - 5G mobile communication KW - millimetre wave antennas KW - multipath channels KW - mmWave indoor scenarios KW - millimetre-wave frequency bands KW - fifth generation networks KW - mmWave frequencies KW - high gain antennas KW - beamforming mechanisms KW - mmWave end-to-end propagation KW - individual ray sources KW - radiation patterns KW - outdoor open area KW - dominant rays KW - radiation pattern KW - path loss KW - multipath components KW - indoor corridor scenarios KW - lower gain antennas KW - multiple ray received power modelling KW - mmWave outdoor scenarios ER - TY - JOUR TI - Solc-style color filters based on multi-twist retarders AU - Li, Lingshan AU - Shi, Shuojia AU - Escuti, Michael J. T2 - NOVEL OPTICAL SYSTEMS, METHODS, AND APPLICATIONS XXIII AB - Birefringent color filters serve a critical role in next generation display systems, including augmented-/virtual- /mixed-reality headsets, and many types of optical remote sensing. Most prior polarization interference filters (PIFs) employ many individually aligned plates that enable only relatively thick color filters (≥ 100s of μm), are usually limited to small clear apertures (few cm), and offer poor off-axis performance. Here, we report on a family of monolithic, thin-film, birefringent PIFs formed using liquid crystal polymer (LCP) network materials, also known as reactive mesogens. These multi-twist retarders (MTRs) are only a few µm thick and have a single alignment surface. They offer high color saturation with a notch-type pass/stopband, analogous to Solc filters, and improved off-axis performance and large-area scalability. Here, we apply simplifying assumptions inspired by Solc-type PIFs, and develop a design method resulting in MTRs with an alternating achiral/chiral architecture. We design three representative color filters (blue-yellow, green-magenta, and cyan-red), and fabricate them. The resulting experimental films manifest strong color filtering behavior, with high saturation and uniformity. We study the color differences for oblique incidence, showing modest change within AOI ≤ 20°. DA - 2020/// PY - 2020/// DO - 10.1117/12.2569133 VL - 11483 SP - SN - 1996-756X KW - Polarization interference filter KW - Liquid crystal polymer ER - TY - JOUR TI - Cardiac Stromal Cell Patch Integrated with Engineered Microvessels Improves Recovery from Myocardial Infarction in Rats and Pigs AU - Su, Teng AU - Huang, Ke AU - Mathews, Kyle G. AU - Scharf, Valery F. AU - Hu, Shiqi AU - Li, Zhenhua AU - Frame, Brianna N. AU - Cores, Jhon AU - Dinh, Phuong-Uyen AU - Daniele, Michael A. AU - Ligler, Frances S. AU - Cheng, Ke T2 - ACS BIOMATERIALS SCIENCE & ENGINEERING AB - The vascularized cardiac patch strategy is promising for ischemic heart repair after myocardial infarction (MI), but current fabrication processes are quite complicated. Vascularized cardiac patches that can promote concurrent restoration of both the myocardium and vasculature at the injured site in a large animal model remain elusive. The safety and therapeutic benefits of a cardiac stromal cell patch integrated with engineered biomimetic microvessels (BMVs) were determined for treating MI. By leveraging a microfluidic method employing hydrodynamic focusing, we constructed the endothelialized microvessels and then encapsulated them together with therapeutic cardiosphere-derived stromal cells (CSCs) in a fibrin gel to generate a prevascularized cardiac stromal cell patch (BMV-CSC patch). We showed that BMV-CSC patch transplantation significantly promoted cardiac function, reduced scar size, increased viable myocardial tissue, promoted neovascularization, and suppressed inflammation in rat and porcine MI models, demonstrating enhanced therapeutic efficacy compared to conventional cardiac stromal cell patches. BMV-CSC patches did not increase renal and hepatic toxicity or exhibit immunogenicity. We noted a significant increase in endogenous progenitor cell recruitment to the peri-infarct region of the porcine hearts treated with BMV-CSC patch as compared to those that received control treatments. These findings establish the BMV-CSC patch as a novel engineered-tissue therapeutic for ischemic tissue repair. DA - 2020/11// PY - 2020/11// DO - 10.1021/acsbiomaterials.0c00942 VL - 6 IS - 11 SP - 6309-6320 SN - 2373-9878 KW - microfluidics KW - cardiac patch KW - cardiac stromal cells KW - myocardial infarction KW - porcine model ER - TY - JOUR TI - Modeling of Antiferromagnetic Dynamics: A Brief Review AU - Semenov, Yuriy G. AU - Kim, Ki Wook T2 - IEEE NANOTECHNOLOGY MAGAZINE AB - This article briefly summarizes the basic principles of several theoretical models that are currently available for the description of antiferromagnetic dynamical response to external forces. The preference is given to simplified phenomenological treatments rather than the rigorous derivation of formalisms. In particular, the origin of ferromagnetic and antiferromagnetic correlations between localized spin moments is examined qualitatively for the simplest models as an introduction to the more sophisticated treatments. An emphasis is placed on elucidating the physical principles underlying the different mechanisms for electrical manipulation of the antiferromagnetic vector. More specifically, the current-induced torques via the spin transfer and the spinorbital interaction are described in a phenomenological manner. In addition, two prospective mechanisms for currentless generation of the desired spin torque are considered as promising alternatives. Following the overall focus, some of the intricate details are not addressed as they are outside the scope of this article. DA - 2020/12// PY - 2020/12// DO - 10.1109/MNANO.2020.3024384 VL - 14 IS - 6 SP - 32-41 SN - 1942-7808 KW - Perpendicular magnetic anisotropy KW - Magnetization KW - Elementary particle exchange interactions KW - Torque KW - Magnetomechanical effects KW - Damping KW - Ferroelectric materials KW - Simulation KW - Computational modeling ER - TY - JOUR TI - Resilient Collaborative Distributed Energy Management System Framework for Cyber-Physical DC Microgrids AU - Cheng, Zheyuan AU - Chow, Mo-Yuen T2 - IEEE TRANSACTIONS ON SMART GRID AB - This article investigates the resilience of the consensus-based distributed economic dispatch (ED) in cyberphysical DC microgrid energy management system (EMS). A holistic framework, called resilient collaborative distributed EMS (R-CoDEMS), is proposed to model the system dynamics, adversaries, and the cybersecurity of the consensus-based distributed ED. Under the R-CoDEMS framework, a reputation-based distributed attack detection and mitigation algorithm is also proposed to improve the system's resilience against typical non-colluding and colluding false data injection attacks. The effectiveness and scalability of the proposed R-CoDEMS countermeasure is evaluated on a typical microgrid system and large-scale networks via numerical simulations. DA - 2020/11// PY - 2020/11// DO - 10.1109/TSG.2020.3001059 VL - 11 IS - 6 SP - 4637-4649 SN - 1949-3061 KW - Microgrids KW - Energy management KW - Resilience KW - Optimization KW - Partial discharges KW - Linear programming KW - Cyber-physical system KW - distributed optimization KW - energy management system KW - false data injection attack KW - microgrid KW - and resilience ER - TY - JOUR TI - Hybrid Precoding for mmWave Massive MIMO With One-Bit DAC AU - Maeng, Sung Joon AU - Yapici, Yavuz AU - Guvenc, Ismail AU - Dai, Huaiyu AU - Bhuyan, Arupjyoti T2 - IEEE Communications Letters AB - Hybrid beamforming is key to achieving energy-efficient 5G wireless networks equipped with massive amount of antennas. Low-resolution data converters bring yet another degree of freedom to energy efficiency for the state-of-the-art 5G transceivers. In this work, we consider the design of hybrid precoders for massive multiple-input multiple-output (MIMO) channels in millimeter-wave (mmWave) spectrum along with one-bit digital-to-analog converters (DACs) and finite-quantized phase shifters. In particular, we propose an alternating-optimization-based precoder design which recursively computes the covariance of the quantization distortion, and updates the precoders accordingly. Numerical results verify that the achievable rate improves quickly through iterations that involve updates to the weight matrix, distortion covariance of the quantization, and the respective precoders. DA - 2020/12// PY - 2020/12// DO - 10.1109/LCOMM.2020.3015674 SP - 1-1 UR - https://doi.org/10.1109/LCOMM.2020.3015674 KW - Radio frequency KW - Quantization (signal) KW - Baseband KW - MIMO communication KW - Array signal processing KW - Distortion KW - Covariance matrices KW - 5G KW - hybrid precoding KW - massive MIMO KW - mmWave communications KW - one-bit DAC ER - TY - CONF TI - A 60 GHz Code-modulated interferometric imaging system using a phased array AU - Chauhan, V. AU - Seo, H. AU - Greene, K. AU - Kam, D.G. AU - Floyd, B. A2 - Robertson, Duncan A. A2 - Wikner, David A. AB - This paper presents a millimeter-wave code-modulated interferometric imaging system, which is a lens-less approach to realizing imagers using repurposed phased arrays. To use a phased array as an interferometer, incoming signals are code modulated using phase shifters, multiplexed using a power combiner, and processed through a shared receiver chain. An interference pattern is then obtained by a squaring operation, from which complex visibilities can be demodulated. Here, a four-element 60-GHz phased array chip is packaged with slot antennas, and a single 60-GHz output is measured using a power detector. This scalar measurement is then demodulated to obtain the interferometric visibilities. The four-element phased array is thinned to obtain a 13-pixel image and the system is demonstrated through a point-source detected at different locations. C2 - 2020/// C3 - Proceedings of SPIE - The International Society for Optical Engineering DA - 2020/// DO - 10.1117/12.2565589 VL - 11411 PB - SPIE UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85086991088&partnerID=MN8TOARS KW - phased array KW - imaging KW - code-modulation KW - millimeter-wave KW - V-band KW - interferometry ER - TY - JOUR TI - A Low-THD Two-Switch PFC DCM Boost Rectifier for Aviation Applications AU - Sadilek, Tomas AU - Kumar, Misha AU - Jang, Yungtaek AU - Barbosa, Peter AU - Husain, Iqbal T2 - IEEE TRANSACTIONS ON TRANSPORTATION ELECTRIFICATION AB - In this article, a new two-switch, single-phase, power-factor-correction, discontinuous-conduction-mode boost rectifier that features zero-voltage switching turn on and can achieve less than 5% input-current total harmonic distortion (THD) by injecting a simple feedforward signal obtained from input and output voltages to the output voltage feedback control is introduced. Since low THD is achieved without high- bandwidth active current shaping control, the proposed topology is suitable for modern aviation applications that require line frequency up to 800 Hz. The evaluation was performed on a 320-W prototype designed to operate from 94-134-V line input and deliver 220-V dc output. The prototype achieves 3.3% THD at full load over the line frequency range from 360 to 800 Hz and meets the required harmonic limits specified by the DO-160 standard that describes the environmental conditions and test procedures for airborne equipment. DA - 2020/12// PY - 2020/12// DO - 10.1109/TTE.2020.2993925 VL - 6 IS - 4 SP - 1755-1766 SN - 2332-7782 KW - Aviation KW - boost rectifier KW - discontinuous-onduction mode (DCM) KW - power-factor correction (PFC) KW - single phase KW - zero-voltage switching (ZVS) ER - TY - JOUR TI - Wirelessly controlled, bioresorbable drug delivery device with active valves that exploit electrochemically triggered crevice corrosion AU - Koo, Jahyun AU - Kim, Sung Bong AU - Choi, Yeon Sik AU - Xie, Zhaoqian AU - Bandodkar, Amay J. AU - Khalifeh, Jawad AU - Yan, Ying AU - Kim, Hojun AU - Pezhouh, Maryam Kherad AU - Doty, Karen AU - Lee, Geumbee AU - Chen, Yu-Yu AU - Lee, Seung Min AU - D’Andrea, Dominic AU - Jung, Kimin AU - Lee, KunHyuck AU - Li, Kan AU - Jo, Seongbin AU - Wang, Heling AU - Kim, Jae-Hwan AU - Kim, Jeonghyun AU - Choi, Sung-Geun AU - Jang, Woo Jin AU - Oh, Yong Suk AU - Park, Inkyu AU - Kwak, Sung Soo AU - Park, Ji-Hyeon AU - Hong, Doosun AU - Feng, Xue AU - Lee, Chi-Hwan AU - Banks, Anthony AU - Leal, Cecilia AU - Lee, Hyuck Mo AU - Huang, Yonggang AU - Franz, Colin K. AU - Ray, Wilson Z. AU - MacEwan, Matthew AU - Kang, Seung-Kyun AU - Rogers, John A. T2 - Science Advances AB - Implantable drug release platforms that offer wirelessly programmable control over pharmacokinetics have potential in advanced treatment protocols for hormone imbalances, malignant cancers, diabetic conditions, and others. We present a system with this type of functionality in which the constituent materials undergo complete bioresorption to eliminate device load from the patient after completing the final stage of the release process. Here, bioresorbable polyanhydride reservoirs store drugs in defined reservoirs without leakage until wirelessly triggered valve structures open to allow release. These valves operate through an electrochemical mechanism of geometrically accelerated corrosion induced by passage of electrical current from a wireless, bioresorbable power-harvesting unit. Evaluations in cell cultures demonstrate the efficacy of this technology for the treatment of cancerous tissues by release of the drug doxorubicin. Complete in vivo studies of platforms with multiple, independently controlled release events in live-animal models illustrate capabilities for control of blood glucose levels by timed delivery of insulin. DA - 2020/8// PY - 2020/8// DO - 10.1126/sciadv.abb1093 VL - 6 IS - 35 SP - eabb1093 J2 - Sci. Adv. LA - en OP - SN - 2375-2548 UR - http://dx.doi.org/10.1126/sciadv.abb1093 DB - Crossref ER - TY - JOUR TI - Sweat-activated biocompatible batteries for epidermal electronic and microfluidic systems AU - Bandodkar, A. J. AU - Lee, S. P. AU - Huang, I. AU - Li, W. AU - Wang, S. AU - Su, C.-J. AU - Jeang, W. J. AU - Hang, T. AU - Mehta, S. AU - Nyberg, N. AU - Gutruf, P. AU - Choi, J. AU - Koo, J. AU - Reeder, J. T. AU - Tseng, R. AU - Ghaffari, R. AU - Rogers, J. A. T2 - Nature Electronics DA - 2020/7/13/ PY - 2020/7/13/ DO - 10.1038/s41928-020-0443-7 VL - 7 IS - 9 SP - 554-562 J2 - Nat Electron LA - en OP - SN - 2520-1131 UR - http://dx.doi.org/10.1038/s41928-020-0443-7 DB - Crossref ER - TY - JOUR TI - Rapid Capture and Extraction of Sweat for Regional Rate and Cytokine Composition Analysis Using a Wearable Soft Microfluidic System AU - Aranyosi, Alexander J. AU - Model, Jeffrey B. AU - Zhang, Michael Z. AU - Lee, Stephen P. AU - Leech, Adam AU - Li, Weihua AU - Seib, Melissa S. AU - Chen, Shulin AU - Reny, Nikolas AU - Wallace, Jessica AU - Shin, Michael H. AU - Bandodkar, Amay J. AU - Choi, Jungil AU - Paller, Amy S. AU - Rogers, John A. AU - Xu, Shuai AU - Ghaffari, Roozbeh T2 - Journal of Investigative Dermatology AB - Sweat is a rich, heterogeneous biofluid that consists of electrolytes (e.g., sodium, chloride, potassium ions), micronutrients (magnesium ion, calcium ion, iron, vitamin c), metabolites (e.g., glucose, lactate, ammonia, urea), hormones (e.g., cortisol, cytokines), and environmental toxins (e.g., ethanol) (Baker et al., 2009Baker L.B. Stofan J.R. Hamilton A.A. Horswill C.A. Comparison of regional patch collection vs. whole body washdown for measuring sweat sodium and potassium loss during exercise.J Appl Physiol (1985). 2009; 107: 887-895Crossref PubMed Scopus (109) Google Scholar, Baker and Wolfe, 2020Baker L.B. Wolfe A.S. Physiological mechanisms determining eccrine sweat composition.Eur J Appl Physiol. 2020; 120: 719-752Crossref PubMed Scopus (36) Google Scholar). Biomarkers in sweat provide insight about underlying physiological and metabolic processes and exhibit changes related to performance, wellness, and health (Baker and Wolfe, 2020Baker L.B. Wolfe A.S. Physiological mechanisms determining eccrine sweat composition.Eur J Appl Physiol. 2020; 120: 719-752Crossref PubMed Scopus (36) Google Scholar). For example, sweat chloride testing is a well-established and routine clinical tool for cystic fibrosis screening in newborns (Gibson and Cooke, 1959Gibson L.E. Cooke R.E. A test for concentration of electrolytes in sweat in cystic fibrosis of the pancreas utilizing pilocarpine by iontophoresis.Pediatrics. 1959; 23: 545-549PubMed Google Scholar, Mishra et al., 2005Mishra A. Greaves R. Massie J. The relevance of sweat testing for the diagnosis of cystic fibrosis in the genomic era.Clin Biochem Rev. 2005; 26: 135-153PubMed Google Scholar). More recently, several studies have demonstrated the efficacy and potential of sweat as a target for monitoring drug levels (e.g., levodopa) for therapeutic dosing (Tai et al., 2019Tai L.C. Liaw T.S. Lin Y. Nyein H.Y.Y. Bariya M. Ji W. et al.Wearable sweat band for noninvasive levodopa monitoring.Nano Lett. 2019; 19: 6346-6351Crossref PubMed Scopus (50) Google Scholar), sweat glucose screening in diabetes management (Lee et al., 2017Lee H. Song C. Hong Y.S. Kim M.S. Cho H.R. Kang T. et al.Wearable/disposable sweat-based glucose monitoring device with multistage transdermal drug delivery module.Sci Adv. 2017; 3e1601314Crossref PubMed Scopus (510) Google Scholar), ethanol levels to assess alcohol intoxication (Gamella et al., 2014Gamella M. Campuzano S. Manso J. González de Rivera G. López-Colino F. Reviejo A.J. et al.A novel non-invasive electrochemical biosensing device for in situ determination of the alcohol content in blood by monitoring ethanol in sweat.Anal Chim Acta. 2014; 806: 1-7Crossref PubMed Scopus (81) Google Scholar), cortisol levels to monitor stress (Torrente-Rodríguez et al., 2020Torrente-Rodríguez R.M. Tu J. Yang Y. Min J. Wang M. Song Y. et al.Investigation of cortisol dynamics in human sweat using a graphene-based wireless mHealth system.Matter. 2020; 2: 921-937Abstract Full Text Full Text PDF PubMed Scopus (87) Google Scholar), and lactate concentrations to track hypoxia (Pribil et al., 2014Pribil M.M. Laptev G.U. Karyakina E.E. Karyakin A.A. Noninvasive hypoxia monitor based on gene-free engineering of lactate oxidase for analysis of undiluted sweat.Anal Chem. 2014; 86: 5215-5219Crossref PubMed Scopus (39) Google Scholar). Quantitative analysis of sweat composition and dynamics currently relies on, first, capturing the sweat using disposable gauzes, absorbent pads, or microtubes followed by sample extraction through centrifuge and gravimetric tools and, finally, off-site analysis of the collected samples by leveraging standard laboratory-based analytical techniques. Of these, the sweat collection and extraction steps are most prone to introducing errors arising from sample contamination, evaporation, and spillage, which affects measurement accuracy, especially for the analysis of small proteins and cytokines in sweat (Dai et al., 2013Dai X. Okazaki H. Hanakawa Y. Murakami M. Tohyama M. Shirakata Y. et al.Eccrine sweat contains IL-1α, IL-1β and IL-31 and activates epidermal keratinocytes as a danger signal.PLoS One. 2013; 8e67666Crossref PubMed Scopus (53) Google Scholar, Katchman et al., 2018Katchman B.A. Zhu M. Blain Christen J. Anderson K.S. Eccrine sweat as a biofluid for profiling immune biomarkers.Proteomics Clin Appl. 2018; 12e1800010Crossref PubMed Scopus (29) Google Scholar). Thus, there is a critical need for uncomplicated and accurate wearable devices that can readily capture sweat in a point-of-care setting (Choi et al., 2018Choi J. Ghaffari R. Baker L.B. Rogers J.A. Skin-interfaced systems for sweat collection and analytics.Sci Adv. 2018; 4: eaar3921Crossref PubMed Scopus (184) Google Scholar, Ray et al., 2019Ray T.R. Choi J. Bandodkar A.J. Krishnan S. Gutruf P. Tian L. et al.Bio-integrated wearable systems: a comprehensive review.Chem Rev. 2019; 119: 5461-5533Crossref PubMed Scopus (369) Google Scholar). Here, we present a soft, skin-interfaced microfluidic patch that facilitates rapid capture and clean extraction of precise volumes of sweat into quantifiable volumes for cytokine analysis. The microfluidic patches were skin mounted on healthy subjects (n = 10) to collect excreted sweat during exposure to heat (40–45 °C) in a controlled environment chamber. The study protocol was approved by the Institutional Review Board of Northwestern University (Evanston, IL) (IRB:STU00208494). Written informed consent was obtained for all subjects. Concentrations of cytokines IL-1α, IL-1RA, and IL-8 were measured across three regions of the arms for each subject diurnally (morning and evening measurements) and on consecutive days (Supplementary Figure S1). These cytokines were chosen because of their direct relevance to inflammatory responses in patients with atopic dermatitis. Sweat samples were analyzed with an immunoassay, thereby introducing a robust wearable platform for tracking sweat rate and inflammation cytokines found in sweat. Soft, wearable microfluidic devices and extraction platforms serve as a collection, storage, extraction, and measurement system that is well-suited for intimate skin coupling and rapid analysis of biofluids in remote settings. The soft wearable device mounts directly on the skin to achieve a water-tight seal. Figure 1a and Supplementary Figure S2 show an exploded view of the multilayered device, highlighting the intricate geometry and ultrathin, impermeable microchannel layers. This six-layer polymeric design is ultrathin and impermeable to external gases, thereby limiting evaporation over several days. This unique material design is ideal for remote clinical trial and at-home settings, where biosamples may require storage for several hours or days in the absence of biofluid handling equipment. The skin adhesion layer lies on the bottom surface of the device and incorporates a small collection area that facilitates the flow of sweat into an inlet port, which in turn connects to the overlying microchannel. The inlet port is limited in size (1–2 mm), which significantly limits contamination issues owing to sweat-to-skin contact prevalent with more conventional sweat collection devices. Sweat entering the inlet area propagates through the microchannel where it is captured (Figure 1b and c). The length and cross-sectional geometry of the microchannel determine the total volume of sweat captured and sweat rate over a given sweat-collection session. Figure 1d shows three microfluidic patches skin mounted on the forearms of a subject. The magnified view in Figure 1d highlights the key physical features of the patch on the epidermis (e.g., microchannel, inlet port, outlet port) and the real-time flow of sweat through the microchannel in a way that is visible to clinical staff. The extraction platform is used to rapidly extract the collected sweat samples into cryovials for analysis, without requiring a centrifuge and other expensive handling equipment (Figure 1e and f and Supplementary Figure S3). To test the sweat rate dependence of cytokine concentrations, we quantified the volume of sweat collected for each sample. The volumetric range of sweat extracted across multiple subjects was 10–233 μl. Linear regression analysis demonstrates that the volume of collected sweat does not correlate with concentrations of IL-1α (y = −7.96× + 2,762; adjusted R2 = 0.08166) or IL-1RA (y = −5.97× + 3,449; adjusted R2 = −0.001975) (Figure 2a). Furthermore, linear regression analysis was conducted for sweat volume and IL-8 (y = −0.0030× + 1.425; adjusted R2 = 0.0720); however, the concentrations of IL-8 in sweat in healthy subjects were near the detection limit of the assay, thereby making a correlation difficult to assess in healthy subjects. These volume-versus-concentration results indicate that IL-1α and IL-RA concentrations are independent of sweat rate across the forearm regions of the body in healthy subjects. Because cytokine concentrations in blood plasma have been shown to vary with diurnal cycles (Petrovsky et al., 1998Petrovsky N. McNair P. Harrison L.C. Diurnal rhythms of pro-inflammatory cytokines: regulation by plasma cortisol and therapeutic implications.Cytokine. 1998; 10: 307-312Crossref PubMed Scopus (226) Google Scholar, Vgontzas et al., 2005Vgontzas A.N. Bixler E.O. Lin H.M. Prolo P. Trakada G. Chrousos G.P. IL-6 and its circadian secretion in humans.Neuroimmunomodulation. 2005; 12: 131-140Crossref PubMed Scopus (247) Google Scholar), we investigated whether a similar phenomenon could be observed with sweat cytokines. Concentrations of IL-1α and IL-1RA were pooled across three anatomic regions (upper left forearm and bilateral lower forearms) and subgrouped by the time of collection (Figure 2b). For sweat samples that were collected during the morning, the median and SD of IL-1α, IL-1RA, and IL-8 concentrations were 789 ± 1,599, 2,639 ± 2,797, and 0.92 ± 0.86 pg/ml, respectively. Concentrations of IL-1α were comparable with those measured using other sweat collection methods (Dai et al., 2013Dai X. Okazaki H. Hanakawa Y. Murakami M. Tohyama M. Shirakata Y. et al.Eccrine sweat contains IL-1α, IL-1β and IL-31 and activates epidermal keratinocytes as a danger signal.PLoS One. 2013; 8e67666Crossref PubMed Scopus (53) Google Scholar, Katchman et al., 2018Katchman B.A. Zhu M. Blain Christen J. Anderson K.S. Eccrine sweat as a biofluid for profiling immune biomarkers.Proteomics Clin Appl. 2018; 12e1800010Crossref PubMed Scopus (29) Google Scholar). For sweat samples that were collected during the evening, the median and SD of IL-1α, IL-1RA, and IL-8 concentrations were 2,639 ± 1,432, 2,340 ± 3,021, and 1.02 ± 0.25 pg/ml, respectively. Wilcoxon rank-sum tests were conducted to compare the cytokine concentrations between morning and evening sample collections. The differences between morning and evening measurements were statistically significant for IL-1α (P = 0.0052) and IL-1RA (P = 0.042), whereas IL-8 (P = 0.59) measurements were not. Unlike plasma, sweat composition could vary with anatomic location (Baker et al., 2009Baker L.B. Stofan J.R. Hamilton A.A. Horswill C.A. Comparison of regional patch collection vs. whole body washdown for measuring sweat sodium and potassium loss during exercise.J Appl Physiol (1985). 2009; 107: 887-895Crossref PubMed Scopus (109) Google Scholar). We analyzed the location dependence of sweat samples collected in the morning and the evening from the different arm locations (Figure 2c). Kruskal–Wallis ANOVA tests demonstrated no significant differences in sweat cytokines collected from the left lower arm, right arm, or upper left arm for both IL-1α (morning: P = 0.58; evening: P = 0.97) and IL-1RA (morning: P = 0.78; evening: P = 0.81). The results of Figure 2 provide insight into the origins of IL-1α and IL-1RA in sweat. The relative independence of cytokine concentrations on sweat rate suggests that the cytokines are present in the sweat produced by the sweat glands rather than dissolved into sweat after being produced by another mechanism (e.g., keratinocytes). This in turn suggests a correlation between cytokine levels in sweat, interstitial fluid, and plasma, providing a potential noninvasive way to track changes in plasma cytokine levels. The presence of such correlation needs to be established through direct measurements. The lack of dependence on anatomic collection location (Figure 2c) and consistency across days (Supplementary Figure S1) indicate that cytokine concentrations are consistent over days and locations in healthy subjects but could vary with time of day for a given subject (Figure 2b). The relative increases in IL-1α and IL-1RA concentrations in the evening compared with those in the morning indicate diurnal fluctuations in sweat cytokine levels, consistent with previous studies of cytokine plasma and sweat cytokine levels (Katchman et al., 2018Katchman B.A. Zhu M. Blain Christen J. Anderson K.S. Eccrine sweat as a biofluid for profiling immune biomarkers.Proteomics Clin Appl. 2018; 12e1800010Crossref PubMed Scopus (29) Google Scholar, Petrovsky et al., 1998Petrovsky N. McNair P. Harrison L.C. Diurnal rhythms of pro-inflammatory cytokines: regulation by plasma cortisol and therapeutic implications.Cytokine. 1998; 10: 307-312Crossref PubMed Scopus (226) Google Scholar, Vgontzas et al., 2005Vgontzas A.N. Bixler E.O. Lin H.M. Prolo P. Trakada G. Chrousos G.P. IL-6 and its circadian secretion in humans.Neuroimmunomodulation. 2005; 12: 131-140Crossref PubMed Scopus (247) Google Scholar). Whether such fluctuations serve a skin-specific role or simply reflect variations in plasma concentrations, requires additional testing across larger populations and different disease subgroups, including atopic dermatitis, urticaria, hyperhidrosis, and other autonomic thermal regulation disorders. The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request. Jeffrey B. Model: http://orcid.org/0000-0003-3052-7076 Michael Z. Zhang: http://orcid.org/0000-0002-7485-8101 Adam Leech: http://orcid.org/0000-0003-3943-1097 Weihua Li: http://orcid.org/0000-0001-5660-5082 Melissa S. Seib: http://orcid.org/0000-0002-9528-0118 Shulin Chen: http://orcid.org/0000-0002-0280-1536 Jessica Wallace: http://orcid.org/0000-0002-2654-7149 Michael H. Shin: http://orcid.org/0000-0002-8803-6862 Amay J. Bandodkar: http://orcid.org/0000-0002-1792-1506 Jungil Choi: http://orcid.org/0000-0002-3659-8978 Amy S. Paller: http://orcid.org/0000-0001-6187-6549 John A. Rogers: http://orcid.org/0000-0002-2980-3961 Shaui Xu: http://orcid.org/0000-0003-3560-6945 AJA, JBM, SPL, AL, WL, NR, MSS, SC, JW, JAR, and RG are cofounders and/or employees of Epicore Biosystems, Cambridge, MA, a company that pursues commercialization of microfluidic devices for wearable applications. The remaining authors state no conflict of interest. This research was funded by LEO Science & Tech Hub . This work utilized the Northwestern University Micro/Nano Fabrication Facility. Conceptualization: AJA, JBM, SPL, JAR, ASP, SX, RG; Data Curation: AJA, MZZ, SPL; Formal Analysis: AJA, MZZ, SPL, RG; Investigation: WL, SC, JC, AJA, MSS, SPL, AJB, RG; Methodology: JBM, AL, NR, JW; Writing - Original Draft Preparation: AJA, MZZ, RG; Writing - Review and Editing: AJA, JBM, SPL, NR, MZZ, MSS, AJB, JW, JAR, ASP, SX, RG Sweat was collected from subjects (n = 10) over a 30–45 minutes period on each of two consecutive days (Supplementary Figure S1). For six of these subjects, the collection was conducted at around the same time each day (five in the morning, one in the evening). For the others, sweat was collected during a morning session and evening session. A custom-built microfluidic patch (Supplementary Figure S2a) designed to collect up to ∼200 μl of sweat, with minimal evaporation (Supplementary Figure S2b), was applied to the epidermis at multiple anatomic positions on the arms. Subjects’ left and right inner volar forearms were examined to ensure that they had intact skin. Subjects with excessive hair in patch application areas had this hair trimmed. The left and right volar forearms were cleaned with sterile alcohol wipes and allowed to dry. Three microfluidic patches were applied to the left proximal, left distal, and right proximal volar forearms (Figure 1d). Subjects entered a sauna to induce sweating. They were allowed to enter and leave ad libitum until 45 minutes had expired or the patches were filled to at least 50 μl, whichever came first. For the first three subjects, sweat was collected until the patches were completely full to ensure that sufficient sweat was available for assay development. Times of patch application and each sauna entry and exit were recorded. Once subjects exited the sauna, patches were removed one at a time and placed on a sweat extraction fixture (Supplementary Figure S3a–c). The exit port of the patch was gently cleaned with an alcohol wipe and positioned over the inlet of a labeled cryovial. Positive pressure applied to the fixture pushed sweat through the channel, out of the exit port and into the cryovial (Supplementary Figure S3d). After closing the vial, the patch was removed and discarded, and the extraction fixture was cleaned with an alcohol wipe. This process was repeated for all patches and subjects for a given collection group. To determine collected sweat volume, a scale was zeroed with an empty cryovial and the differential weight of each filled vial was measured. When the fluid volume was very low (∼15 μl or less), the resulting weight was sometimes zero or negative owing to variation among the vials. Protease and phosphatase inhibitor cocktails were each added at 10% v/v. Vials were then vortexed and stored at −80 °C. When all subject samples had been collected and prepared, the samples were shipped overnight on dry ice to a bioassay laboratory (Pacific BioLabs, Hercules, CA) for analysis. Sweat was analyzed using U-PLEX assay kits (Meso Scale Diagnostics, Rockville, MD). Because these kits were not designed specifically for sweat, a series of spike-recovery tests were performed to refine and validate the measurement process. For the resulting process, the samples were rapidly thawed and centrifuged. The supernatant was extracted and diluted in the ratio of 1:2 in PBS to raise the pH. The samples were then processed following the instructions in the kit. Subject samples were analyzed following this same process. Three subjects had sweat samples collected during both morning and evening, and the cytokine concentrations were directly compared. In all cases, concentrations of IL-1α and IL-1RA from samples collected in the evening were higher for a given subject. Mean ratios (evening to morning) were 4.2 for IL-1α (range 1.4–5.8) and 4.6 for IL-1RA (range 2.7–5.5). In one subject from whom three samples were collected, concentrations rose from morning to evening on the first day, then fell again the following morning (IL-1α: 857–3,982–603 pg/ml; IL-1RA: 733–3,267–456 pg/ml). To explore the repeatability of sweat cytokine measurements, samples were collected from each subject on two sequential days. For the purpose of this comparison, only samples collected at the same time of the day (both in the morning or both in the evening) were included. Supplementary Figure S1 shows that IL-1α and IL-1RA concentrations were highly correlated across days for healthy subjects. However, the slope of the linear regression fit for IL-1α was less than one (∼0.57), indicating a shift in concentrations by a factor of ∼2 across a small sample size. DA - 2020/6// PY - 2020/6// DO - 10.1016/j.jid.2020.05.107 VL - 6 J2 - Journal of Investigative Dermatology LA - en OP - SN - 0022-202X UR - http://dx.doi.org/10.1016/j.jid.2020.05.107 DB - Crossref ER - TY - JOUR TI - Transmission of a broadband FSK signal from a dynamically tuned narrowband antenna AU - Srivastava, Shruti AU - Adams, Jacob J. T2 - IET MICROWAVES ANTENNAS & PROPAGATION AB - A frequency reconfigurable patch antenna is dynamically tuned to transmit frequency-shift keying (FSK) signals over a range of frequencies much broader than the static impedance bandwidth of the antenna. Experiments are conducted for two binary FSK schemes having different carrier spacing. In both cases, dynamic tuning of the antenna is shown to increase the amplitude of the radiated signal by providing a better match than the static antenna. However, the average energy of the radiated bit at each carrier frequency decreases as the symbol rate increases beyond the 3 dB bandwidth of the antenna. Therefore, the bandwidth of the antenna is found to be a limiting factor for the maximum achievable data rate in this scheme. As an alternative to shorter bit durations, the authors show that a higher level FSK scheme using dynamic tuning is able to increase throughput beyond what is possible with a static antenna. DA - 2020/10/28/ PY - 2020/10/28/ DO - 10.1049/iet-map.2020.0387 VL - 14 IS - 13 SP - 1651-1654 SN - 1751-8733 KW - microstrip antennas KW - frequency shift keying KW - broadband antennas KW - carrier spacing KW - dynamic tuning KW - static antenna KW - carrier frequency KW - symbol rate KW - maximum achievable data rate KW - broadband FSK signal KW - dynamically tuned narrowband antenna KW - frequency reconfigurable patch antenna KW - frequency-shift keying signals KW - static impedance bandwidth KW - binary FSK schemes KW - radiated signal amplitude ER - TY - JOUR TI - Energy Harvesting in Unmanned Aerial Vehicle Networks With 3D Antenna Radiation Patterns AU - Turgut, Esma AU - Gursoy, M. Cenk AU - Guvenc, Ismail T2 - IEEE Transactions on Green Communications and Networking AB - In this paper, an analytical framework is provided to analyze the energy coverage performance of unmanned aerial vehicle (UAV) energy harvesting networks with clustered user equipments (UEs). Locations of UEs are modeled as a Poisson Cluster Process (PCP), and UAVs are assumed to be located at a certain height above the center of user clusters. Hence, user-centric UAV deployments are addressed. Two different models are considered for the line-of-sight (LOS) probability function to compare their effects on the network performance. Moreover, antennas with doughnut-shaped radiation patterns are employed at both UAVs and UEs, and the impact of practical 3D antenna radiation patterns on the network performance is also investigated. Initially, the path loss of each tier is statistically described by deriving the complementary cumulative distribution function and probability density function. Following this, association probabilities with each tier are determined, and energy coverage probability of the UAV network is characterized in terms of key system and network parameters for UAV deployments both at a single height level and more generally at multiple heights. Through numerical results, we have shown that cluster size and UAV height play crucial roles on the energy coverage performance. Furthermore, energy coverage probability is significantly affected by the antenna orientation and number of UAVs in the network. DA - 2020/12// PY - 2020/12// DO - 10.1109/TGCN.2020.3007588 VL - 4 IS - 4 SP - 1149-1164 UR - https://doi.org/10.1109/TGCN.2020.3007588 KW - Unmanned aerial vehicles (UAVs) KW - energy harvesting KW - energy coverage probability KW - Poisson point processes KW - Poisson cluster processes KW - Thomas cluster processes KW - 3D antenna radiation patterns KW - stochastic geometry ER - TY - JOUR TI - Epitaxial 4H-SiC based Schottky diode temperature sensors in ultra-low current range AU - Kumar, Vibhor AU - Verma, Jyoti AU - Maan, A. S. AU - Akhtar, Jamil T2 - VACUUM AB - This work reports highly sensitive and linear temperature sensors based on epitaxial silicon carbide (SiC). Circular shaped Ni/4H-nSiC Schottky barrier diode (SBD) temperature sensors of area 3.140 mm2 have been fabricated and characterized in forward current (If) and temperature range from 10 pA to 5 nA and 233 K–473 K, respectively. The highest value of absolute thermal sensitivity |S| has been achieved as 3.425 mV/K at the lowest If = 10 pA. The sensors show best performance at If = 0.1 nA with lowest root mean square error, temperature error and highest coefficient of determination as 5.341 mV, 1.620 K and 99.96%, respectively, with |S| = 3.295 mV/K. Moreover, for If ≤ 20 pA, sensors reach their maximum operating temperature point, i.e., 448 K. The highest value of self-heating in the sensors have been calculated as 1.623 nK. Moreover, asymmetry has been observed between experimental and the theoretical values of |S| which are explained using variation in the barrier height patches (probably caused by defects at the interface) parameter like their effective area, radius, number, barrier height at the saddle point, with the temperature. DA - 2020/12// PY - 2020/12// DO - 10.1016/j.vacuum.2020.109590 VL - 182 SP - SN - 0042-207X KW - SiC Schottky Barrier diode KW - Temperature sensor KW - Thermal sensitivity KW - Barrier height inhomogeneity KW - Self-heating ER - TY - JOUR TI - Security of Microfluidic Biochip: Practical Attacks and Countermeasures AU - Chen, Huili AU - Potluri, Seetal AU - Koushanfar, Farinaz T2 - ACM TRANSACTIONS ON DESIGN AUTOMATION OF ELECTRONIC SYSTEMS AB - With the advancement of system miniaturization and automation, Lab-on-a-Chip (LoC) technology has revolutionized traditional experimental procedures. Microfluidic Biochip (MFB) is an emerging branch of LoC with wide medical applications such as DNA sequencing, drug delivery, and point of care diagnostics. Due to the critical usage of MFBs, their security is of great importance. In this article, we exploit the vulnerabilities of two types of MFBs: Flow-based Microfluidic Biochip (FMFB) and Digital Microfluidic Biochip (DMFB). We propose a systematic framework for applying Reverse Engineering (RE) attacks and Hardware Trojan (HT) attacks on MFBs as well as for practical countermeasures against the proposed attacks. We evaluate the attacks and defense on various benchmarks where experimental results prove the effectiveness of our methods. Security metrics are defined to quantify the vulnerability of MFBs. The overhead and performance of the proposed attacks as well as countermeasures are also discussed. DA - 2020/5// PY - 2020/5// DO - 10.1145/3382127 VL - 25 IS - 3 SP - SN - 1557-7309 KW - Microfluidic biochip KW - security KW - hardware Trojans KW - hardware obfuscation KW - camouflaging KW - Trojan detection ER - TY - JOUR TI - Flexible composites with Ce-doped BaTiO3/P(VDF-TrFE) nanofibers for piezoelectric device AU - Zhuang, Yongyong AU - Li, Jinglei AU - Hu, Qingyuan AU - Han, Shuang AU - Liu, Weihua AU - Peng, Chang AU - Li, Zhong AU - Zhang, Lin AU - Wei, Xiaoyong AU - Xu, Zhuo T2 - COMPOSITES SCIENCE AND TECHNOLOGY AB - Flexible piezoelectric energy harvesting devices based on inorganic piezoelectric materials have attracted wide attention for their outstanding physical properties and potential applications. Different strategies, such as adding ductile elements, increasing sintering time, sintering in various atmospheres, mixing with organic compounds which usually is not only for piezoelectric materials, are also used to fabricate highly flexible devices. However, these methods always accompanied by a sharp reduction in piezoelectric performance, and then the sensitivity of the device will be reduced. Here, The flexible piezoelectric energy harvesting device by mixing Ce-doped barium titanate (BaTiO3, BTO) nanofibers with poly (vinylidene fluoride-trifluorethylene) [P(VDF-TrFE)] nanofibers is studied. Due to the introduction of P(VDF-TrFE) nanofibers, the device show high flexibility. The device with high output signal is obtained, since both fillers are piezoelectric materials. The results show that the output power density of the device fabricated by Ce-BTO/P(VDF-TrFE) composite nanofibers is about six times larger than the device obtained by P(VDF-TrFE) nanofibers. This proposed method is expected to provide reference for the development of future nanoscale piezoelectric-based energy harvesting devices and sensors. DA - 2020/11/10/ PY - 2020/11/10/ DO - 10.1016/j.compscitech.2020.108386 VL - 200 SP - SN - 1879-1050 KW - Polymer-matrix composites (PMCs) KW - Nano composites KW - Smart materials KW - Electrical properties ER - TY - JOUR TI - P(VDF-TrFE) Thin-Film-Based Transducer for Under-Display Ultrasonic Fingerprint Sensing Applications AU - Peng, Chang AU - Chen, Mengyue AU - Wang, Hongchao AU - Shen, Jian AU - Jiang, Xiaoning T2 - IEEE SENSORS JOURNAL AB - The use of fingerprint for biometric identification is one of the most prevalent authentication methods applied today in smartphones. In the course of pursuing narrow-bezel and full-screen display, the under-display fingerprint sensor is considered to be a user-friendly and practical solution for newer models of smartphone. While under-display optical fingerprint sensor has been commercially available in various smartphones, it demonstrates limitations such as sensitivity to humidity and contaminations including oil and water as well as easy to spoof. Ultrasonic fingerprint sensing has been proved to be able to overcome these limitations. In this study, P(VDF-TrFE) piezoelectric polymer-based transducer was reported, for the first time, for under-display ultrasonic fingerprint sensing applications. In specific, a 40 MHz ultrasonic transducer using a layer of 10~μm thick P(VDF-TrFE) thin-film was designed, fabricated, and characterized. The under-display ultrasonic fingerprint sensing capability of the prototyped transducer was experimentally validated using phantoms of real fingerprint. Electronic images of fingerprint with resolution of 500 ×DPI were obtained through under-display ultrasonic fingerprint sensing tests. The lateral resolution of the transducer was calculated to be ~70μm . The results of this study illustrate promising advances in under-display ultrasonic fingerprint sensing applications. DA - 2020/10/1/ PY - 2020/10/1/ DO - 10.1109/JSEN.2020.2997375 VL - 20 IS - 19 SP - 11221-11228 SN - 1558-1748 KW - Fingerprint sensing KW - under-display sensing KW - ultrasonic transducer KW - P(VDF-TrFE) ER - TY - JOUR TI - Accurate colorimetric images using LEDs AU - Trussell, Henry J. AU - Shamey, Renzo T2 - JOURNAL OF ELECTRONIC IMAGING AB - It is well known that more than three or four spectral measurements are required for accurate measurement of color under arbitrary illumination. Previous work has shown 6 to 10 measurements can yield accurate results on average, but with significant numbers of errors above the threshold of obvious visual detection. We demonstrate an imaging system (LED box) consisting of a monochrome camera, multiple LED illumination in a diffuse reflecting chamber that produces excellent color capture in perceptual quality measured in ΔE00. We evaluate this system with respect to practical applications with emphasis on textile quality assessment. Our system of 12 LEDs produces average and maximum training ΔE00 errors around 0.7 and 2.4, respectively; and average and maximum testing ΔE00 errors around 1.5 and 5.0, respectively. This performance exceeds that of reported colorimetric camera systems, except highly specialized configurations. We find that the stability of the system to LED variability under operating conditions is good. We show that pseudoinverse estimate produces better results than the MMSE estimate under actual operating conditions. DA - 2020/7// PY - 2020/7// DO - 10.1117/1.JEI.29.4.043008 VL - 29 IS - 4 SP - SN - 1560-229X KW - color image processing KW - colorimetric KW - accurate color ER - TY - JOUR TI - Dictionary Learning for Channel Estimation in Hybrid Frequency-Selective mmWave MIMO Systems AU - Xie, Hongxiang AU - Gonzalez-Prelcic, Nuria T2 - IEEE Transactions on Wireless Communications AB - Exploiting channel sparsity at millimeter wave (mmWave) frequencies reduces the high training overhead associated with the channel estimation stage. Compressive sensing (CS) channel estimation techniques usually adopt the (overcomplete) Fourier transform matrix as sparsifying dictionary. This may not be the best choice when considering hardware impairments in practical arrays. We propose two dictionary learning (DL) algorithms to learn the best sparsifying dictionaries for channel matrices from observations obtained with practical hybrid frequency-selective mmWave multiple-input-multiple-output (MIMO) systems. First, we optimize the combined dictionary, i.e., the Kronecker product of transmit and receive dictionaries, as it is used in practice to sparsify the channel matrix. This stage operates as a calibration phase, since all the hardware imperfections are embedded into the learnt dictionaries. Second, considering the different array structures at the transmitter and receiver, we exploit separable DL to find the best transmit and receive dictionaries. Once the channel is expressed in terms of the optimized dictionaries, various CS-based sparse recovery techniques can be applied for low overhead channel estimation. The effectiveness of the proposed DL algorithms under low SNR conditions has been corroborated via numerical simulations with different system configurations, array geometries and hardware impairments. DA - 2020/11// PY - 2020/11// DO - 10.1109/TWC.2020.3011126 VL - 19 IS - 11 SP - 7407-7422 UR - https://doi.org/10.1109/TWC.2020.3011126 KW - Dictionaries KW - Channel estimation KW - Antenna arrays KW - MIMO communication KW - Hardware KW - Calibration KW - Channel models KW - Dictionary learning KW - compressive sensing KW - mmWave MIMO KW - channel estimation KW - manufacturing errors KW - array calibration KW - array manifold disturbance KW - antenna gain KW - phase error KW - mutual coupling KW - hybrid architecture KW - ADMM KW - sparse coding ER - TY - JOUR TI - Droop and Oscillator Based Grid-Forming Converter Controls: A Comparative Performance Analysis AU - Awal, M. A. AU - Yu, Hui AU - Lukic, Srdjan AU - Husain, Iqbal T2 - FRONTIERS IN ENERGY RESEARCH AB - Two distinct approaches, one droop based phasor domain modeled and the other nonlinear oscillator based time domain modeled, have emerged for the analysis and control of power electronic converters at the system interface layer where these converters are integrating distributed energy resources (DERs). While the droop type controllers are based on distinct time-scale separation of control loops, purposefully slowing down the response of the DERs, the oscillator based controllers deliver fast dynamic response with accurate power sharing capability as well as stability guarantee. In this paper, we analyze both the droop and oscillator type converters in the context of grid forming converters with respect to steady state terminal response, transient stability, and harmonic compensation in converter output current or in network voltage. Simulation and experimental results are provided to demonstrate the easier implementation of oscillator based controls that can also achieve supplementary control objectives pertinent to power quality. DA - 2020/10/7/ PY - 2020/10/7/ DO - 10.3389/fenrg.2020.00168 VL - 8 SP - SN - 2296-598X KW - droop controls KW - oscillator controls KW - grid forming converters KW - harmonic compensation KW - transient stability KW - virtual oscillator control KW - VOC KW - dVOC ER - TY - JOUR TI - Editorial: Special Issue on Selected Papers From ISICAS 2020 Guest Editors' Introduction AU - Atef, M. AU - Hung, C. -C. AU - Jia, Y. AU - Lee, S. -Y. AU - Sahin, M. T2 - IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS AB - The papers in this special section were presented at the 2020 International Symposium on Integrated Circuits and Systems (ISICAS) in a virtual conference that was held from August 27–28, 2020. DA - 2020/10// PY - 2020/10// DO - 10.1109/TBCAS.2020.3026225 VL - 14 IS - 5 SP - 930-930 SN - 1940-9990 KW - Special issues and sections KW - Meetings KW - Integrated circuits ER - TY - JOUR TI - Methodology for Benchmarking Radio-Frequency Channel Sounders Through a System Model AU - Gentile, Camillo AU - Molisch, Andreas F. AU - Chuang, Jack AU - Michelson, David G. AU - Bodi, Anuraag AU - Bhardwaj, Anmol AU - Ozdemir, Ozgur AU - Khawaja, Wahab Ali Gulzar AU - Guvenc, Ismail AU - Cheng, Zihang AU - Rottenberg, Francois AU - Choi, Thomas AU - Mueller, Robert AU - Han, Niu AU - Dupleich, Diego T2 - IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS AB - Development of a comprehensive channel propagation model for high-fidelity design and deployment of wireless communication networks necessitates an exhaustive measurement campaign in a variety of operating environments and with different configuration settings. As the campaign is time-consuming and expensive, the effort is typically shared by multiple organizations, inevitably with their own channel-sounder architectures and processing methods. Without proper benchmarking, it cannot be discerned whether observed differences in the measurements are actually due to the varying environments or to discrepancies between the channel sounders themselves. The simplest approach for benchmarking is to transport participant channel sounders to a common environment, collect data, and compare results. Because this is rarely feasible, this paper proposes an alternative methodology - which is both practical and reliable - based on a mathematical system model to represent the channel sounder. The model parameters correspond to the hardware features specific to each system, characterized through precision, in situ calibration to ensure accurate representation; to ensure fair comparison, the model is applied to a ground-truth channel response that is identical for all systems. Five worldwide organizations participated in the cross-validation of their systems through the proposed methodology. Channel sounder descriptions, calibration procedures, and processing methods are provided for each organization as well as results and comparisons for 20 ground-truth channel responses. DA - 2020/10// PY - 2020/10// DO - 10.1109/TWC.2020.3003617 VL - 19 IS - 10 SP - 6504-6519 SN - 1558-2248 UR - https://doi.org/10.1109/TWC.2020.3003617 KW - Antenna measurements KW - Calibration KW - Wireless communication KW - Standards KW - Benchmark testing KW - Antenna arrays KW - Channel models KW - Antenna KW - measurement KW - propagation KW - cross-validation KW - millimeter-wave KW - mmWave ER - TY - JOUR TI - Multi-Fidelity Surrogate-Based Optimization for Electromagnetic Simulation Acceleration AU - Wang, Yi AU - Franzon, Paul D. AU - Smart, David AU - Swahn, Brian T2 - ACM TRANSACTIONS ON DESIGN AUTOMATION OF ELECTRONIC SYSTEMS AB - As circuits’ speed and frequency increase, fast and accurate capture of the details of the parasitics in metal structures, such as inductors and clock trees, becomes more critical. However, conducting high-fidelity 3D electromagnetic (EM) simulations within the design loop is very time consuming and computationally expensive. To address this issue, we propose a surrogate-based optimization methodology flow, namely multi-fidelity surrogate-based optimization with candidate search (MFSBO-CS), which integrates the concept of multi-fidelity to reduce the full-wave EM simulation cost in analog/RF simulation-based optimization problems. To do so, a statistical co-kriging model is adapted as the surrogate to model the response surface, and a parallelizable perturbation-based adaptive sampling method is used to find the optima. Within the proposed method, low-fidelity fast RC parasitic extraction tools and high-fidelity full-wave EM solvers are used together to model the target design and then guide the proposed adaptive sample method to achieve the final optimal design parameters. The sampling method in this work not only delivers additional coverage of design space but also helps increase the accuracy of the surrogate model efficiently by updating multiple samples within one iteration. Moreover, a novel modeling technique is developed to further improve the multi-fidelity surrogate model at an acceptable additional computation cost. The effectiveness of the proposed technique is validated by mathematical proofs and numerical test function demonstration. In this article, MFSBO-CS has been applied to two design cases, and the result shows that the proposed methodology offers a cost-efficient solution for analog/RF design problems involving EM simulation. For the two design cases, MFSBO-CS either reaches comparably or outperforms the optimization result from various Bayesian optimization methods with only approximately one- to two-thirds of the computation cost. DA - 2020/10// PY - 2020/10// DO - 10.1145/3398268 VL - 25 IS - 5 SP - SN - 1557-7309 KW - Statistical machine learning KW - surrogate-based optimization KW - multi-fidelity KW - electromagnetic simulation ER - TY - JOUR TI - Photoinduced tunable birefringence and dichroism in silver nanogratings AU - Talebi, Razieh AU - Ghahfarokhi, Forough Taheri AU - Vashaee, Daryoosh T2 - JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS AB - Silver nanogratings are anisotropic plasmonic nanostructures with potential application in optical components due to their large birefringence and dichroism. We induced linear birefringence and linear dichroism in subwavelength Ag-AgCl films by irradiating with a single low-power linearly polarized laser beam. The laser beam aligns silver nanoparticles in the direction of laser polarization and forms nanograting. We used Stokes parameters to determine linear birefringence and linear dichroism in silver aligned nanostructures. The values of linear dichroism and linear birefringence in silver nanogratings are controllable through manipulating the spatial period of nanogratings. The dispersion characteristic of dichroism and birefringence is also investigated. DA - 2020/10/1/ PY - 2020/10/1/ DO - 10.1364/JOSAB.399604 VL - 37 IS - 10 SP - 2848-2855 SN - 1520-8540 ER - TY - JOUR TI - Planar 2-D Beam Steering Antenna Using Liquid Metal Parasitics AU - Bharambe, Vivek T. AU - Adams, Jacob J. T2 - IEEE Transactions on Antennas and Propagation AB - We demonstrate a single-feed planar antenna capable of 2-D beam-steering using pumped liquid metal (LM) parasitics. Instead of relying on phase shifters for beam-steering, the proposed antenna employs LM plugs acting as parasitic elements to achieve up to ±48° steering in the H-plane and ±54° steering in the E-plane. The antenna can also steer in diagonal and OFF-diagonal planes using a combination of the E and H plane steering techniques. Simultaneously, the antenna maintains a 2:1 VSWR for all the states. By creating a composite realized gain plot for all these states, it is seen that the antenna can cover as much as 23% of the spherical area with at least 5 dBi of realized gain, compared to 4.5% in the absence of LM parasitic elements for beam-steering. We also quantify the pattern diversity (PD) and illustrate that the antenna achieves a greater PD than an electrically scanned 2 × 2 phased array occupying an equivalent aperture (0.55λ 0 × 0.66λ 0 ). DA - 2020/11// PY - 2020/11// DO - 10.1109/TAP.2020.2998219 VL - 68 IS - 11 SP - 7320-7327 UR - https://doi.org/10.1109/TAP.2020.2998219 KW - 3-D printing KW - beam steering antenna KW - liquid metal (LM) parasitics KW - microfluidics KW - reconfigurable antenna ER - TY - JOUR TI - Guest Editors' Introduction to the Special Issue on Hardware Security AU - Awad, Amro AU - Wang, Rujia T2 - IEEE TRANSACTIONS ON COMPUTERS AB - The twelve papers in this special section focus on hardware security. This topic is becoming a significant challenge in modern computing systems. Recently discovered hardware vulnerabilities, such as Spectre and Meltdown, are striking evidence that today’s computing systems are untenable without deliberate consideration of the security aspects at the design time. The papers address various topics related to hardware security: secure-by-design architectures, secure speculative execution, secure system integration of untrusted chiplets, malware detection, program analysis using power side channels, architecture support for forensics, and efficient implementations of security modules. DA - 2020/11/1/ PY - 2020/11/1/ DO - 10.1109/TC.2020.3021223 VL - 69 IS - 11 SP - 1556-1557 SN - 1557-9956 KW - Special issues and sections KW - Hardware KW - Security KW - Computer architecture KW - System integration ER - TY - JOUR TI - Multi-junction solar cells by Intermetallic Bonding and interconnect of Dissimilar Materials: GaAs/Si AU - Hagar, Brandon AU - Sayed, Islam AU - Colter, Peter C. AU - Bedair, S. M. T2 - SOLAR ENERGY MATERIALS AND SOLAR CELLS AB - We present a novel, low temperature approach to multijunction solar cell fabrication combining the high efficiency multi-junction concept with the low cost of thin film technology in one solar cell structure. The intermetallic bonding approach presented is based on joining indium metal which has been deposited on the metal contact grid of the respective solar cells. This approach avoids the problems of lattice mismatch and tunnel junction limitations, connecting solar cells of potentially any material with patterned contacts. No measurable increase in resistance has been measured between bonded materials. This method allows the independent development of each cell technology for use in multijunction solar cells. This technique can be applied to any commercial off-the-shelf solar cells, if available. A GaAs/Si multijunction solar cell bonded using this approach is demonstrated. The silicon cell is off-the-shelf with textured surface and commercial metal contacts. This is integrated with an in-house grown thin film GaAs cell. The GaAs/Si device is demonstrated in both two and three terminal configurations. DA - 2020/9/15/ PY - 2020/9/15/ DO - 10.1016/j.solmat.2020.110653 VL - 215 SP - SN - 1879-3398 KW - Solar cells KW - Intermetallic bonding KW - Wafer bonding technology KW - Mechanical stacking ER - TY - JOUR TI - An Improved CMUT Structure Enabling Release and Collapse of the Plate in the Same Tx/Rx Cycle for Dual-Frequency Acoustic Angiography AU - Mahmud, Marzana Mantasha AU - Wu, Xun AU - Sanders, Jean Lunsford AU - Biliroglu, Ali Onder AU - Adelegan, Oluwafemi Joel AU - Newsome, Isabel G. AU - Yamaner, Feysel Yalcin AU - Dayton, Paul A. AU - Oralkan, Omer T2 - IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control AB - This study demonstrates, in detail, the potential of using capacitive micromachined ultrasonic transducers (CMUTs) for acoustic angiography of the microvasculature. It is known that when ultrasound contrast agents (microbubbles) are excited with moderate acoustic pressure around their resonance (2-4 MHz), they produce higher order harmonics (greater than third harmonic) due to their nonlinear behavior. To date, the fundamental challenge has been the availability of a transducer that can generate the transmit signals to excite the microbubbles at low frequencies and, in the same cycle, confocally detect harmonics in the higher frequencies. We present a novel device structure and dual-mode operation of a CMUT that operates with a center frequency of 4.3 MHz and 150% bandwidth in the conventional mode for transmitting and a center frequency of 9.8 MHz and a 125.5% bandwidth in collapse mode for receiving. Output pressure of 1.7 MPapp is achieved on the surface of a single unfocused transducer. The mechanical index at the transducer surface is 0.56. FEM simulations are performed first to show the functionality of the proposed device, and then, the device fabrication is described in detail. Finally, we experimentally demonstrate the ability to detect the microbubble signals with good contrast, and the background reflection is adequately suppressed, indicating the feasibility of the presented approach for acoustic angiography. DA - 2020/11// PY - 2020/11// DO - 10.1109/TUFFC.2020.3001221 VL - 67 IS - 11 SP - 2291-2302 UR - https://doi.org/10.1109/TUFFC.2020.3001221 KW - Acoustics KW - Imaging KW - Transducers KW - Ultrasonic imaging KW - Finite element analysis KW - Electrodes KW - Frequency control KW - Contrast-enhanced ultrasound imaging KW - dual-mode operation KW - high-frequency (HF) receive KW - insulation spacers KW - low-frequency (LF) transmit KW - microbubbles ER - TY - JOUR TI - A Data-Driven Pivot-Point-Based Time-Series Feeder Load Disaggregation Method AU - Wang, Jiyu AU - Zhu, Xiangqi AU - Liang, Ming AU - Meng, Yao AU - Kling, Andrew AU - Lubkeman, David L. AU - Lu, Ning T2 - IEEE Transactions on Smart Grid AB - The load profile at a feeder-head is usually known to utility engineers while the nodal load profiles are not. However, the nodal load profiles are increasingly important for conducting time-series analysis in distribution systems. Therefore, in this paper, we present a pivot-point based, two-stage feeder load disaggregation algorithm using smart meter data. The two stages are load profile selection (LPS) and load profile allocation (LPA). In the LPS stage, a random load profile selection process is first executed to meet the load diversity requirement. Then, a few pairs of pivot points are selected as the matching targets. After that, a matching algorithm will run repetitively to select one load profile at a time for matching the reference load profile at the pivot points. In the LPA stage, the LPS selected load profiles are allocated to each load node on the feeder considering distribution transformer loading limits, load composition, and square-footage. The proposed method is validated using actual data collected in a North Carolina service area. Simulation results show that the proposed method can generate a unique load shape for each load node while match the shape of their aggregated profile with the actual feeder head load profile. DA - 2020/11// PY - 2020/11// DO - 10.1109/TSG.2020.3008603 VL - 11 IS - 6 SP - 5396-5406 UR - https://doi.org/10.1109/TSG.2020.3008603 KW - Wind power generation KW - Optimization KW - Generators KW - Power systems KW - Computational modeling KW - Uncertainty KW - Distribution system KW - feeder load disaggregation KW - load profile KW - power system planning KW - power system operation KW - time-series analysis KW - smart meter data ER - TY - JOUR TI - The 2020 UV emitter roadmap AU - Amano, Hiroshi AU - Collazo, Ramon AU - Santi, Carlo De AU - Einfeldt, Sven AU - Funato, Mitsuru AU - Glaab, Johannes AU - Hagedorn, Sylvia AU - Hirano, Akira AU - Hirayama, Hideki AU - Ishii, Ryota AU - Kashima, Yukio AU - Kawakami, Yoichi AU - Kirste, Ronny AU - Kneissl, Michael AU - Martin, Robert AU - Mehnke, Frank AU - Meneghini, Matteo AU - Ougazzaden, Abdallah AU - Parbrook, Peter J. AU - Rajan, Siddharth AU - Reddy, Pramod AU - Roemer, Friedhard AU - Ruschel, Jan AU - Sarkar, Biplab AU - Scholz, Ferdinand AU - Schowalter, Leo J. AU - Shields, Philip AU - Sitar, Zlatko AU - Sulmoni, Luca AU - Wang, Tao AU - Wernicke, Tim AU - Weyers, Markus AU - Witzigmann, Bernd AU - Wu, Yuh-Renn AU - Wunderer, Thomas AU - Zhang, Yuewei T2 - JOURNAL OF PHYSICS D-APPLIED PHYSICS AB - Solid state UV emitters have many advantages over conventional UV sources. The (Al,In,Ga)N material system is best suited to produce LEDs and laser diodes from 400 nm down to 210 nm—due to its large and tuneable direct band gap, n- and p-doping capability up to the largest bandgap material AlN and a growth and fabrication technology compatible with the current visible InGaN-based LED production. However AlGaN based UV-emitters still suffer from numerous challenges compared to their visible counterparts that become most obvious by consideration of their light output power, operation voltage and long term stability. Most of these challenges are related to the large bandgap of the materials. However, the development since the first realization of UV electroluminescence in the 1970s shows that an improvement in understanding and technology allows the performance of UV emitters to be pushed far beyond the current state. One example is the very recent realization of edge emitting laser diodes emitting in the UVC at 271.8 nm and in the UVB spectral range at 298 nm. This roadmap summarizes the current state of the art for the most important aspects of UV emitters, their challenges and provides an outlook for future developments. DA - 2020/12/9/ PY - 2020/12/9/ DO - 10.1088/1361-6463/aba64c VL - 53 IS - 50 SP - SN - 1361-6463 KW - ultraviolet KW - light emitting diodes KW - InGaN KW - UV-LED KW - AlGaN ER - TY - JOUR TI - Cyber-Physical Microgrids: Toward Future Resilient Communities AU - Vu, Tuyen V. AU - Nguyen, Bang L. H. AU - Cheng, Zheyuan AU - Chow, Mo-Yuen AU - Zhang, Bin T2 - IEEE INDUSTRIAL ELECTRONICS MAGAZINE AB - Microgrids can be isolated from large-scale power transmission/distribution systems (macrogrids) to deliver energy to their local communities using local energy resources and distribution systems when power outages occur in the macrogrids. In such situations, microgrids could be considered the last available resource to provide energy to critical infrastructure. DA - 2020/9// PY - 2020/9// DO - 10.1109/MIE.2019.2958039 VL - 14 IS - 3 SP - 4-17 SN - 1941-0115 KW - Microgrids KW - Monitoring KW - Resilience KW - Control systems KW - Market research KW - Robustness KW - Power measurement ER - TY - JOUR TI - 3D construct of hydroxyapatite/zinc oxide/palladium nanocomposite scaffold for bone tissue engineering AU - Heidari, Fatemeh AU - Tabatabaei, Fahimeh Sadat AU - Razavi, Mehdi AU - Lari, Reza Bazargan AU - Tavangar, Mina AU - Romanos, Georgios E. AU - Vashaee, Daryoosh AU - Tayebi, Lobat T2 - JOURNAL OF MATERIALS SCIENCE-MATERIALS IN MEDICINE DA - 2020/9/30/ PY - 2020/9/30/ DO - 10.1007/s10856-020-06409-2 VL - 31 IS - 10 SP - SN - 1573-4838 ER - TY - JOUR TI - A Systematic Approach for Stator MMF Harmonic Elimination Using Three-Layer Fractional Slot Winding AU - Islam, Md Sariful AU - Kabir, Md Ashfanoor AU - Mikail, Rajib AU - Husain, Iqbal T2 - IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS AB - A systematic approach based on a novel space-shifted three-layer winding (SSTLW) to eliminate both the sub- and superharmonics of fractional slot concentrated winding ac machines is presented. In this proposed three-layer fractional slot winding, the number of turns in one layer and the relative positions of other two layers are optimized to cancel subharmonics. The cancellation of superharmonics is achieved through series connection of two SSTLWs through effective doubling of the number of slots. The cancellation of the dominant sub- and superharmonics using this approach leads to reducing the total harmonic distortion, torque ripple, PM eddy current loss, and rotor core loss, while simultaneously improving power factor and saliency ratio. The proposed design methodology and ensuring improvements have been validated through finite element analysis for the widely used 12-slot/10-pole and 18-slot/14-pole permanent magnet synchronous machine (PMSM) configurations. A prototype three-layer winding is built for a 10-pole PMSM to validate the simulation results experimentally. DA - 2020/// PY - 2020/// DO - 10.1109/TIA.2020.2984195 VL - 56 IS - 4 SP - 3516-3525 SN - 1939-9367 KW - Windings KW - Harmonic analysis KW - Power capacitors KW - Stator windings KW - Rotors KW - Systematics KW - Fractional slot winding KW - MMF space harmonics KW - multilayer winding KW - permanent magnet (PM) machines KW - PM eddy current loss ER - TY - JOUR TI - Modeling, design guidelines, and detection limits of self-powered enzymatic biofuel cell-based sensors AU - Jin, Xin AU - Bandodkar, Amay J. AU - Fratus, Marco AU - Asadpour, Reza AU - Rogers, John A. AU - Alam, Muhammad A. T2 - Biosensors and Bioelectronics AB - Enzymatic biofuel cell (EBFC)-based self-powered biochemical sensors obviate the need for external power sources thus enabling device miniaturization. While recent efforts driven by experimentalists illustrate the potential of EBFC-based sensors for real-time monitoring of physiologically relevant biochemicals, a robust mathematical model that quantifies the contributions of sensor components and empowers experimentalists to predict sensor performance is missing. In this paper, we provide an elegant yet simple equivalent circuit model that captures the complex, three-dimensional interplay among coupled catalytic redox reactions occurring in an EBFC-based sensor and predicts its output signal with high correlations to experimental observations. The model explains the trade-off among chemical design parameters such as the surface density of enzymes, various reaction constants as well as electrical parameters in the Butler–Volmer relationship. The model shows that the linear dynamic range and sensitivity of the EBFC-based sensor can be independently fine-tuned by changing the surface density of enzymes and electron mediators at the anode and by enhancing reductant concentrations at the cathode. The mathematical model derived in this work can be easily adapted to understand a wide range of two-electrode systems, including sensors, fuel cells, and energy storage devices. DA - 2020/11// PY - 2020/11// DO - 10.1016/j.bios.2020.112493 VL - 168 SP - 112493 J2 - Biosensors and Bioelectronics LA - en OP - SN - 0956-5663 UR - http://dx.doi.org/10.1016/j.bios.2020.112493 DB - Crossref KW - Enzymatic biofuel cell KW - Modeling KW - Biosensor KW - Self-powered KW - Wearable and bio-implantable ER - TY - JOUR TI - Don’t Sweat It: The Quest for Wearable Stress Sensors AU - Bandodkar, Amay J. AU - Ghaffari, Roozbeh AU - Rogers, John A. T2 - Matter AB - A nervous sweat may seem like an inconvenience, but your body could be releasing important signals. Herein, Gao and colleagues develop a wearable sensor with integrated microfluidics, immunoassays, and electronics for tracking cortisol in sweat—as a biomarker of stress. A nervous sweat may seem like an inconvenience, but your body could be releasing important signals. Herein, Gao and colleagues develop a wearable sensor with integrated microfluidics, immunoassays, and electronics for tracking cortisol in sweat—as a biomarker of stress. Stress is an intense, natural, and universal reaction that guides both cognitive and physical processes with beneficial short-term consequences attributed to “fight-or-flight” responses and harmful long-term consequences to health. Recent studies show that chronic stress accumulated over time can lead to debilitating outcomes such as cancer, coronary heart disease, accidental injuries, lung disease, liver disease and suicide.1Yao B.C. Meng L.B. Hao M.L. Zhang Y.M. Gong T. Guo Z.G. Chronic stress: a critical risk factor for atherosclerosis.J. Int. Med. Res. 2019; 47: 1429-1440Crossref Scopus (43) Google Scholar The World Health Organization estimates that stress-related disorders are one of the leading causes of disability globally and classifies stress as the “health epidemic of the 21st century”.2Kalia M. Assessing the economic impact of stress--the modern day hidden epidemic.Metabolism. 2002; 51: 49-53Abstract Full Text PDF PubMed Scopus (168) Google Scholar According to the American Psychological Association, over 80% of workers in the United States suffer from work-related stress, costing businesses a staggering $300 billion annually.3American Psychological Association42 Worrying Workplace Stress Statistics.https://www.stress.org/42-worrying-workplace-stress-statisticsDate: 2019Google Scholar Although the underlying causes can vary widely, the frequency and intensity of stressful events are rising sharply, due in part to the increasing influence of social media on daily life.4Aalbers G. McNally R.J. Heeren A. de Wit S. Fried E.I. Social media and depression symptoms: A network perspective.J. Exp. Psychol. Gen. 2019; 148: 1454-1462Crossref Scopus (117) Google Scholar Extensive research suggests that such stress can exacerbate or even cause serious medical conditions beyond those described above, including depressive and post-traumatic disorders, Alzheimer’s and Parkinson’s diseases, inflammatory conditions, and diabetes.5Deak T. Quinn M. Cidlowski J.A. Victoria N.C. Murphy A.Z. Sheridan J.F. Neuroimmune mechanisms of stress: sex differences, developmental plasticity, and implications for pharmacotherapy of stress-related disease.Stress. 2015; 18: 367-380Crossref PubMed Scopus (62) Google Scholar The clinical standard for assessing stress relies on questionnaires and surveys. The subjective nature of these techniques lack both quantitative rigor and temporal resolution necessary to aid in the development of precise medical interventions. Methodologies are, however, beginning to shift to techniques that exploit biochemical markers that are known to quantitatively relate to stress levels. A team of researchers at Caltech, led by Prof. Wei Gao, report an important contribution to this area of research in the form of a monitoring system that accurately captures instances of stress based on evaluation of key biomarker concentrations in sweat.6Torrente-Rodríguez R.M. Tu J. Yang Y. Min J. Wang M. Song Y. Yu Y. Xu C. Ye C. IsHak W.W. et al.Investigation of Cortisol Dynamics in Human Sweat Using a Graphene-Based Wireless mHealth System.Matter. 2020; 2 (this issue): 921-937Abstract Full Text Full Text PDF PubMed Scopus (161) Google Scholar The sensor platform leverages a collection of advances in nanotechnology, sweat sampling, immunosensing, and flexible, wireless electronics. At physiological levels, stress activates the sympathetic nervous system, the hypothalamic pituitary adrenal axis, and the immune system, collectively resulting in elevated levels of cortisol—a hormone that controls the body’s “fight-or-flight” reaction.7Kraemer W.J. French D.N. Spiering B.A. Volek J.S. Sharman M.J. Ratamess N.A. Judelson D.A. Silvestre R. Watson G. Gómez A. Maresh C.M. Cortitrol supplementation reduces serum cortisol responses to physical stress.Metabolism. 2005; 54: 657-668Abstract Full Text Full Text PDF PubMed Scopus (25) Google Scholar As a result, the concentration of cortisol yields a diagnostic correlate for stress.8Herane Vives A. De Angel V. Papadopoulos A. Strawbridge R. Wise T. Young A.H. Arnone D. Cleare A.J. The relationship between cortisol, stress and psychiatric illness: New insights using hair analysis.J. Psychiatr. Res. 2015; 70: 38-49Crossref PubMed Scopus (79) Google Scholar The conventional method for quantifying cortisol levels requires collection samples of blood using standard clinical techniques, and then analysis for cortisol using benchtop instrumentation. The result yields accurate measurements of cortisol levels but only at discrete time points, performed by trained personnel in specialized facilities. Practical limitations associated with these procedures prevent rapid medical interventions, thereby increasing the potential for stress related health complications. Emerging methods that rely on chemical analysis of hair and saliva provide non-invasive alternatives, but they retain requirements for manual collection and measurement. The wearable device reported by the Caltech team promises to enable continuous, real-time assessments of cortisol levels in a non-invasive, automated fashion through analysis of small volumes of sweat. The result could fundamentally change the way that we monitor stress levels on a daily basis. Sweat possesses several important attributes that are attractive for this type of non-invasive, autonomous physiological monitoring. For example, the human body produces a considerable amount of this relatively underexplored class of biofluid.9Taylor N.A.S. Machado-Moreira C.A. Regional variations in transepidermal water loss, eccrine sweat gland density, sweat secretion rates and electrolyte composition in resting and exercising humans.Extrem. Physiol. Med. 2013; 2: 4Crossref PubMed Scopus (279) Google Scholar More importantly, sweat contains a rich mixture of important biochemical markers,10Harvey C.J. LeBouf R.F. Stefaniak A.B. Formulation and stability of a novel artificial human sweat under conditions of storage and use.Toxicol. In Vitro. 2010; 24: 1790-1796Crossref PubMed Scopus (170) Google Scholar including cortisol,11Russell E. Koren G. Rieder M. Van Uum S.H. The detection of cortisol in human sweat: implications for measurement of cortisol in hair.Ther. Drug Monit. 2014; 36: 30-34PubMed Google Scholar that can yield insights into health status. Nevertheless, most prior studies of sweat focus mainly on handful of electrolytes, metabolites, and minerals. The work of Torrente-Rodríguez et al.6Torrente-Rodríguez R.M. Tu J. Yang Y. Min J. Wang M. Song Y. Yu Y. Xu C. Ye C. IsHak W.W. et al.Investigation of Cortisol Dynamics in Human Sweat Using a Graphene-Based Wireless mHealth System.Matter. 2020; 2 (this issue): 921-937Abstract Full Text Full Text PDF PubMed Scopus (161) Google Scholar represents a significant contribution to this growing field in the form of graphene-based, wireless, wearable devices capable of measuring cortisol levels in sweat, as it emerges from the surface of the skin (Figure 1). Systematic benchtop and human subject studies demonstrate the key features and capabilities of this system as well as strong correlations between cortisol levels in sweat, blood serum, and saliva samples. The results have direct implications for the continuous, accurate monitoring of stress levels, without the need for surveys or specialized equipment. The design and fabrication of these devices build on the authors’ expertise in graphene-based sweat sensors.12Yang Y. Song Y. Bo X. Min J. Pak O.S. Zhu L. Wang M. Tu J. Kogan A. Zhang H. et al.A laser-engraved wearable sensor for sensitive detection of uric acid and tyrosine in sweat.Nat. Biotechnol. 2020; 38: 217-224Crossref Scopus (432) Google Scholar The process begins with synthesis of graphene on a flexible film of polyimide via directed laser ablation. A layer of a conducting polymer–poly(pyrrole propionic acid) – grown on top of the graphene exposes surface chemical groups that promote attachment of an anti-cortisol monoclonal antibody designed to selectively bind cortisol via the (1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysulfosuccinimide (Sulfo-NHS) cross-linker. Proof of concept testing uses manually collected sweat diluted with buffer containing a fixed amount of enzyme-labeled cortisol (horseradish-peroxidase-labeled cortisol). Introducing such a sample onto the sensor leads to competitive binding between cortisol in the sweat and the enzyme-labeled cortisol. Adding hydroquinone—a molecule that reacts with enzymes on the sensor surface—produces hydrogen peroxide. An integrated wireless electronic system that applies a negative potential (−0.2 V) to the sensor leads to electrochemical reduction of the hydrogen peroxide and production of an associated current that serves as a signal with magnitude proportional to the concentration of cortisol. An integrated version of this sensor exploits microfluidic handling capabilities to allow the binding step to be performed directly while the device is on the skin. With this platform, sweat cortisol levels measured in human subjects during and post-exercise show strong correlations to corresponding concentrations in blood and saliva. These levels also exhibit expected variations associated with daily circadian rhythms, intense physical activity, and stress induced by placing a hand in cold water, where each study demonstrates different aspects of applicability in practical scenarios. Beyond the monitoring of cortisol, these systems may have broader utility in the application of sweat in biochemical monitoring of the physiological status. Specifically, the combination of graphene electrodes, immunosensing techniques, flexible electronics, and skin-compatible microfluidics have great potential in non-invasive health tracking, ranging from mental health management, military training, and human performance to cancer treatment and cardiac therapy. Combining these biochemical sensing capabilities with co-integrated systems for measuring biophysical signatures such as body temperature, heart rate, respiration rate, blood pressure, and others suggest a promising future for personalized, data-enabled health care and preventative medicine. Investigation of Cortisol Dynamics in Human Sweat Using a Graphene-Based Wireless mHealth SystemTorrente-Rodríguez et al.MatterFebruary 26, 2020In BriefA fully integrated, flexible, and miniaturized wireless mHealth sensing device based on laser-engraved graphene and immunosensing with proven utility for fast, reliable, sensitive, and non-invasive monitoring of stress hormone cortisol is developed. Pilot human study results revealed a strong correlation between sweat and circulating hormone for the first time. Both cortisol diurnal cycle and dynamic stress-response profiles were established from human sweat, reflecting the potential of such mHealth devices in personalized healthcare and human performance evaluation. Full-Text PDF Open Archive DA - 2020/4// PY - 2020/4// DO - 10.1016/j.matt.2020.03.004 VL - 2 IS - 4 SP - 795-797 J2 - Matter LA - en OP - SN - 2590-2385 UR - http://dx.doi.org/10.1016/j.matt.2020.03.004 DB - Crossref ER - TY - JOUR TI - Utility Rate Making: An Intersection of Economics and Social Good [Guest Editorial] AU - Lu, Ning AU - Hong, Tao T2 - IEEE Power and Energy Magazine AB - Utility rate making is becoming increasingly critical. The high penetration of distributed energy resources changes not only the landscape of utility operating and planning practices but also the business models that govern how utilities recover their service costs. The objective of power generation and delivery has changed from considering only the delivery of reliable and cost-effective energy services to also accounting for sustainability and minimizing adverse environmental impacts. Today’s energy systems are evolving from traditional highly centralized suppliers to multiple distributed small suppliers or even self-suppliers. This evolution could be further accelerated when major technology breakthroughs in energy storage and photovoltaics (PVs) make these systems less expensive, more reliable, and more efficient. All of these electric system changes greatly affect many traditional rate-making principles, methodologies, and processes. DA - 2020/5// PY - 2020/5// DO - 10.1109/MPE.2020.2972665 VL - 18 IS - 3 SP - 14-16 UR - https://doi.org/10.1109/MPE.2020.2972665 KW - Special issues and sections KW - Electricity supply industry KW - Pricing KW - Power system economics KW - Security KW - Power generation KW - Tariffs ER - TY - JOUR TI - Battery Model Parameterization Using Manufacturer Datasheet and Field Measurement for Real-Time HIL Applications AU - Xie, Fuhong AU - Yu, Hui AU - Long, Qian AU - Zeng, Wente AU - Lu, Ning T2 - IEEE Transactions on Smart Grid AB - This paper presents a novel battery model parameterization method using actual field measurement and manufacturer datasheet for real-time hardware-in-the-loop (HIL) applications. It is critical that real-time HIL models can accurately reproduce field test results so that tests can be conducted on HIL testbeds instead of in the field. In the past, numerical heuristic optimization algorithms were often used to derive parameters for battery models. However, the deterministic algorithms often reach a locally optimal solution and stochastic heuristic searching strategies suffer from low searching efficiency. Therefore, in this paper, we propose a global-local searching enhanced genetic algorithm (GL-SEGA). By applying the generalized opposition-based learning mechanism, GL-SEGA can efficiently explore the global solution space. By using the trust-region-reflective method to perform the local search, the GL-SEGA can improve the accuracy and convergence in its local exploitations. Field measurements and manufactory datasheets are used to test and validate the accuracy and robustness of the GL-SEGA algorithm. DA - 2020/5// PY - 2020/5// DO - 10.1109/TSG.2019.2953718 VL - 11 IS - 3 SP - 2396-2406 UR - https://doi.org/10.1109/TSG.2019.2953718 KW - Battery model KW - genetic algorithm KW - opposition based learning KW - parameterization KW - trust-region-reflective ER - TY - JOUR TI - On Microstructure Estimation Using Flatbed Scanners for Paper Surface Based Authentication AU - Liu, Runze AU - Wong, Chau-Wai T2 - arXiv preprint arXiv:2008.13000 DA - 2020/// PY - 2020/// ER - TY - JOUR TI - Method, apparatus, and system for object tracking sensing using broadcasting AU - Lai, Hung-quoc Duc AU - Claffey, David N AU - Chen, Chen AU - Zhang, Feng AU - Wu, Chenshu AU - Chau-Wai, WONG AU - Wang, Beibei AU - Au, Oscar Chi-lim AU - Liu, KJ Ray DA - 2020/8// PY - 2020/8// N1 - US Patent 10,742,475 RN - US Patent 10,742,475 ER - TY - JOUR TI - Adaptive Multi-Trace Carving for Robust Frequency Tracking in Forensic Applications AU - Zhu, Qiang AU - Chen, Mingliang AU - Wong, Chau-Wai AU - Wu, Min T2 - IEEE Transactions on Information Forensics and Security AB - In the field of information forensics, many emerging problems involve a critical step that estimates and tracks weak frequency components in noisy signals. It is often challenging for the prior art of frequency tracking to i) achieve a high accuracy under noisy conditions, ii) detect and track multiple frequency components efficiently, or iii) strike a good trade-off of the processing delay versus the resilience and the accuracy of tracking. To address these issues, we propose Adaptive Multi-Trace Carving (AMTC), a unified approach for detecting and tracking one or more subtle frequency components under very low signal-to-noise ratio (SNR) conditions and in near real time. AMTC takes as input a time-frequency representation of the system's preprocessing results (such as the spectrogram), and identifies frequency components through iterative dynamic programming and adaptive trace compensation. The proposed algorithm considers relatively high energy traces sustaining over a certain duration as an indicator of the presence of frequency/oscillation components of interest and track their time-varying trend. Extensive experiments using both synthetic data and real-world forensic data of power signatures and physiological monitoring reveal that the proposed method outperforms representative prior art under low SNR conditions, and can be implemented in near real-time settings. The proposed AMTC algorithm can empower the development of new information forensic technologies that harness very small signals. DA - 2020/// PY - 2020/// DO - 10.1109/tifs.2020.3030182 UR - http://dx.doi.org/10.1109/tifs.2020.3030182 KW - Frequency estimation KW - Forensics KW - Spectrogram KW - Signal to noise ratio KW - Estimation KW - Hidden Markov models KW - Dynamic programming KW - Spectrogram KW - multi-trace tracking KW - dynamic programming KW - heart rate KW - electric network frequency (ENF) ER - TY - JOUR TI - 3-D Trajectory Optimization in UAV-Assisted Cellular Networks Considering Antenna Radiation Pattern and Backhaul Constraint AU - Chowdhury, Md Moin Uddin AU - Maeng, Sung Joon AU - Bulut, Eyuphan AU - Guvenc, Ismail T2 - IEEE Transactions on Aerospace and Electronic Systems AB - This article explores the effects of 3-D antenna radiation pattern and backhaul constraint on optimal 3-D path planning problem of an unmanned aerial vehicle (UAV), in interference prevalent downlink cellular networks. We consider a cellular-connected UAV that is tasked to travel between two locations within a fixed time, and it can be used to improve the cellular connectivity of ground users by acting as a relay. Since the antenna gain of a cellular base station changes significantly with the UAV altitude, the UAV can improve the signal quality in its backhaul link by changing its height over the course of its mission. This problem is nonconvex, and thus, we explore the dynamic programming technique to solve it. We show that the 3-D optimal paths can introduce significant network performance gain over the trajectories with fixed UAV heights. DA - 2020/10// PY - 2020/10// DO - 10.1109/TAES.2020.2981233 VL - 56 IS - 5 SP - 3735-3750 UR - https://doi.org/10.1109/TAES.2020.2981233 KW - Three-dimensional displays KW - Antenna radiation patterns KW - Trajectory KW - Cellular networks KW - Interference KW - Relays KW - Unmanned aerial vehicles KW - Antenna radiation KW - backhaul KW - dynamic programming (DP) KW - trajectory KW - unmanned aerial vehicle (UAV) ER - TY - JOUR TI - Guest Editorial: Next Generation of Synchrophasor-based Power System Monitoring, Operation and Control AU - Zhao, Junbo AU - Srivastava, Anurag AU - Chakrabortty, Aranya AU - Terzija, Vladimir AU - Kamwa, Innocent AU - Bi, Tianshu AU - Zhang, Yingchen T2 - IET GENERATION TRANSMISSION & DISTRIBUTION DA - 2020/10/2/ PY - 2020/10/2/ DO - 10.1049/iet-gtd.2020.1315 VL - 14 IS - 19 SP - 3943-3944 SN - 1751-8695 ER - TY - JOUR TI - Robust Group Subspace Recovery: A New Approach for Multi-Modality Data Fusion AU - Ghanem, Sally AU - Panahi, Ashkan AU - Krim, Hamid AU - Kerekes, Ryan A. T2 - IEEE SENSORS JOURNAL AB - Robust Subspace Recovery (RoSuRe) algorithm was recently introduced as a principled and numerically efficient algorithm that unfolds underlying Unions of Subspaces (UoS) structure, present in the data. The union of Subspaces (UoS) is capable of identifying more complex trends in data sets than simple linear models. We build on and extend RoSuRe to prospect the structure of different data modalities individually. We propose a novel multi-modal data fusion approach based on group sparsity which we refer to as Robust Group Subspace Recovery (RoGSuRe). Relying on a bi-sparsity pursuit paradigm and non-smooth optimization techniques, the introduced framework learns a new joint representation of the time series from different data modalities, respecting an underlying UoS model. We subsequently integrate the obtained structures to form a unified subspace structure. The proposed approach exploits the structural dependencies between the different modalities data to cluster the associated target objects. The resulting fusion of the unlabeled sensors' data from experiments on audio and magnetic data has shown that our method is competitive with other state of the art subspace clustering methods. The resulting UoS structure is employed to classify newly observed data points, highlighting the abstraction capacity of the proposed method. DA - 2020/// PY - 2020/// DO - 10.1109/JSEN.2020.2999461 VL - 20 IS - 20 SP - 12307-12316 SN - 1558-1748 KW - Sensor fusion KW - Data integration KW - Data models KW - Sparse matrices KW - Magnetic sensors KW - Sensor phenomena and characterization KW - Sparse learning KW - unsupervised classification KW - data fusion KW - multimodal data ER - TY - JOUR TI - Buckle-Delamination-Enabled Stretchable Silver Nanowire Conductors AU - Wu, Shuang AU - Yao, Shanshan AU - Liu, Yuxuan AU - Hu, Xiaogang AU - Huang, He Helen AU - Zhu, Yong T2 - ACS APPLIED MATERIALS & INTERFACES AB - Controlled buckling and delamination of thin films on a compliant substrate has attracted much attention for applications ranging from micro/nanofabrication to flexible and stretchable electronics to bioengineering. Here, a highly conductive and stretchable conductor is fabricated by attaching a polymer composite film (with a thin layer of silver nanowires embedded below the surface of the polymer matrix) on top of a prestretched elastomer substrate followed with releasing the prestrain. A partially delaminated wavy geometry of the polymer film is created. During the evolution of the buckle-delamination, the blisters pop-up randomly but self-adjust into a uniform distribution, which effectively reduces the local strain in the silver nanowires. The resistance change of the conductor is less than 3% with the applied strain up to 100%. A theoretical model on the buckle-delamination structure is developed to predict the geometrical evolution, which agrees well with experimental observation. Finally, an integrated silver nanowire/elastomer sensing module and a stretchable thermochromic device are developed to demonstrate the utility of the stretchable conductor. This work highlights the important relevance of mechanics-based design in nanomaterial-enabled stretchable devices. DA - 2020/9/16/ PY - 2020/9/16/ DO - 10.1021/acsami.0c09775 VL - 12 IS - 37 SP - 41696-41703 SN - 1944-8252 KW - stretchable conductor KW - silver nanowire KW - buckling KW - buckle-delamination KW - wrinkling KW - thermochromic ER - TY - JOUR TI - Advances in High-Power Wireless Charging Systems: Overview and Design Considerations AU - Feng, Hao AU - Tavakoli, Reza AU - Onar, Omer C. AU - Pantic, Zeljko T2 - IEEE TRANSACTIONS ON TRANSPORTATION ELECTRIFICATION AB - Wireless charging systems are foreseen as an effective solution to improve the convenience and safety of conventional conductive chargers. As this technology has matured, recent broad applications of wireless chargers to electrified transportation have indicated a trend toward higher power, power density, modularity, and scalability of designs. In this article, commercial systems and laboratory prototypes are reviewed, focusing mostly on the advances in high-power wireless charging systems. The recent endeavors in magnetic pad designs, compensation networks, power electronics converters, control strategies, and communication protocols are illustrated. Both stationary and dynamic (in-motion) wireless charging systems are discussed, and critical differences in their designs and applications are emphasized. On that basis, the comparisons among different solutions and design considerations are summarized to present the essential elements and technology roadmap that will be necessary to support large-scale deployment of high-power wireless charging systems. The review is concluded with the discussion of several fundamental challenges and prospects of high-power wireless power transfer (WPT) systems. Foreseen challenges include utilization of advanced materials, electric and electromagnetic field measurement and mitigation, customization, communications, power metering, and cybersecurity. DA - 2020/// PY - 2020/// DO - 10.1109/TTE.2020.3012543 VL - 6 IS - 3 SP - 886-919 SN - 2332-7782 KW - High-power wireless chargers KW - transportation electrification KW - wireless charging systems ER - TY - JOUR TI - Distributed Event-Triggered H-infinity Consensus Based Current Sharing Control of DC Microgrids Considering Uncertainties AU - Zhou, Jianguo AU - Xu, Yinliang AU - Sun, Hongbin AU - Wang, Liming AU - Chow, Mo-Yuen T2 - IEEE TRANSACTIONS ON INDUSTRIAL INFORMATICS AB - The uncertainties caused by sources [such as wind power and photovoltaic (PV)], load switchings, and the equivalent negative impedance of constant power loads (CPLs) commonly exist in microgrids and often undermine the system stability and damping. In this article, a distributed secondary H consensus approach with an eventtriggered communication scheme is proposed for dc microgrids to achieve accurate current sharing and satisfactory performance in the presence of CPLs and uncertainties. Different from many existing works, the proposed eventtriggered communication scheme only requires the information at every fixed sampled interval without the Zenobehavior and continuous-time information. Then, global large-signal stability of the dc microgrid with CPLs and uncertainties under the proposed distributed control is analyzed, where a primary plug-and-play (PnP) voltage controller is considered for each distributed generator (DG). Furthermore, effects of key controller parameters and CPLs on the dynamic performance is analyzed, and a PnP design method is presented for the primary-secondary controllers. With the proposed method, full PnP operation of the dc microgrid can be realized and communication burden can be considerably reduced. Finally, simulation results are presented to validate the proposed method. DA - 2020/12// PY - 2020/12// DO - 10.1109/TII.2019.2961151 VL - 16 IS - 12 SP - 7413-7425 SN - 1941-0050 KW - DC microgrids KW - current sharing KW - constant power loads (CPLs) KW - distributed control KW - H-infinity consensus KW - event-triggered control KW - uncertainty ER - TY - JOUR TI - A Novel Frequency Support Control Method for PV Plants Using Tracking LQR AU - Li, Qinmiao AU - Baran, Mesut E. T2 - IEEE TRANSACTIONS ON SUSTAINABLE ENERGY AB - Growing level of Photovoltaic (PV) generation challenges the conventional generation control in power systems, as the current PV systems do not possess inertia or governor system. However, a supervisory control can be adopted for such PV systems to provide frequency support. In this article, a novel controller for large-scale PV plants is proposed for this purpose. Different than other approaches which only focus on emulating droop and inertial response of local PV, the proposed approach uses a tracking linear quadratic regulator (LQR) based controller to help the system frequency effectively track that of a designed reference system with given inertia and droop constants. To design the LQR, an unknown input observer (UIO) is adopted to estimate the system states, as well as the unknown disturbance. We also introduce a small-signal PV system model which is suitable for designing frequency support controls. The model is validated against the detailed nonlinear PV system model, and the effectiveness of the proposed controller is demonstrated using a standard test system. Test results also show that the proposed method achieves the desired frequency response more effectively than the alternative method from literature, while the later method is liable to over-compensation of frequency response at the price of requiring more power reserve in PV. DA - 2020/10// PY - 2020/10// DO - 10.1109/TSTE.2019.2953684 VL - 11 IS - 4 SP - 2263-2273 SN - 1949-3037 KW - Frequency response KW - linear quadratic regulator (LQR) KW - photovoltaic (PV) KW - small-signal model (SSM) KW - unknown input observer (UIO) ER - TY - CONF TI - Deep Learning-Based Beam Alignment in Mmwave Vehicular Networks AU - Myers, N.J. AU - Wang, Y. AU - Gonzalez-Prelcic, N. AU - Heath, R.W. AB - Millimeter wave channels exhibit structure that allows beam alignment with fewer channel measurements than exhaustive beam search. From a compressed sensing (CS) perspective, the received channel measurements are usually obtained by multiplying a CS matrix with a sparse representation of the channel matrix. Due to the constraints imposed by analog frontends, designing CS matrices that efficiently exploit the channel structure is challenging. In this paper, we propose an end-to-end deep learning technique to design a structured CS matrix that is well suited to the underlying channel distribution, leveraging both sparsity and the particular spatial structure that appears in vehicular channels. The channel measurements acquired with the designed CS matrix are then used to predict the best beam for link configuration. Simulation results for vehicular communication channels indicate that our deep learning-based approach achieves better beam alignment than standard CS techniques that use the random phase shift-based design. C2 - 2020/// C3 - ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings DA - 2020/// DO - 10.1109/ICASSP40776.2020.9054075 VL - 2020-May SP - 8569-8573 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85089217043&partnerID=MN8TOARS ER - TY - CONF TI - 5G V2X communication at millimeter wave: Rate maps and use cases AU - Zheng, W. AU - Ali, A. AU - Gonzalez-Prelcic, N. AU - Heath, R.W. AU - Klautau, A. AU - Pari, E.M. AB - Millimeter wave (mmWave) has the potential to offer high data rates for vehicle-to-everything (V2X) communication. In this paper, we provide an introduction to important use cases of V2X as they pertain to fifth generation (5G) communication networks. As 5G technology is still evolving to support vehicles, and mmWave is reflected and blocked by vehicles, it remains unclear if the target rates for the use cases can be achieved. Motivated by the different data rate requirements, we introduce a methodology for evaluating rates in 5G mmWave V2X scenarios. Our approach leverages available city CAD models, realistic traffic simulators, and industry standard ray tracing tools to allow site-specific propagation evaluation. This approach may be used to devise insight into the role of traffic density, antenna array placement, and base station density in important urban propagation settings. Results are provided that highlight the application to develop a rate map for an urban intersection. They show that rate increases in dense deployments by more than ten percent per base station, but only decreases about one percent when going from light to heavy traffic. C2 - 2020/// C3 - IEEE Vehicular Technology Conference DA - 2020/// DO - 10.1109/VTC2020-Spring48590.2020.9128612 VL - 2020-May UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85088315072&partnerID=MN8TOARS ER - TY - JOUR TI - Effect of Microwave Processing and Glass Inclusions on Thermoelectric Properties of P-Type Bismuth Antimony Telluride Alloys for Wearable Applications AU - Nozariasbmarz, Amin AU - Vashaee, Daryoosh T2 - ENERGIES AB - Depending on the application of bismuth telluride thermoelectric materials in cooling, waste heat recovery, or wearable electronics, their material properties, and geometrical dimensions should be designed to optimize their performance. Recently, thermoelectric materials have gained a lot of interest in wearable electronic devices for body heat harvesting and cooling purposes. For efficient wearable electronic devices, thermoelectric materials with optimum properties, i.e., low thermal conductivity, high Seebeck coefficient, and high thermoelectric figure-of-merit (zT) at room temperature, are demanded. In this paper, we investigate the effect of glass inclusion, microwave processing, and annealing on the synthesis of high-performance p-type (BixSb1−x)2Te3 nanocomposites, optimized specially for body heat harvesting and body cooling applications. Our results show that glass inclusion could enhance the room temperature Seebeck coefficient by more than 10% while maintaining zT the same. Moreover, the combination of microwave radiation and post-annealing enables a 25% enhancement of zT at room temperature. A thermoelectric generator wristband, made of the developed materials, generates 300 μW power and 323 mV voltage when connected to the human body. Consequently, MW processing provides a new and effective way of synthesizing p-type (BixSb1−x)2Te3 alloys with optimum transport properties. DA - 2020/9// PY - 2020/9// DO - 10.3390/en13174524 VL - 13 IS - 17 SP - SN - 1996-1073 KW - thermoelectric materials KW - microwave processing KW - bismuth telluride KW - nanocomposites KW - body heat harvesting KW - glass inclusion KW - annealing KW - wearable cooler ER - TY - JOUR TI - Object Labeling in 3D from Multi-view Scenes Using Gaussian-Hermite Moment-Based Depth Map AU - Enan, Sadman Sakib AU - Rahman, S. M. Mahbubur AU - Haque, Samiul AU - Howlader, Tamanna AU - Hatzinakos, Dimitrios T2 - PROCEEDINGS OF 3RD INTERNATIONAL CONFERENCE ON COMPUTER VISION AND IMAGE PROCESSING, CVIP 2018, VOL 2 AB - Depth as well as intensityEnan, Sadman Sakib of a pixel plays a significantMahbubur Rahman, S. M. role in labeling objectsHatzinakos, Dimitrios in 3D environmentsHaque, Samiul. This paper presentsHowlader, Tamanna a novel approach of labeling objects from multi-view video sequences by incorporating rich depth information. The depth map of a scene is estimated from focus-cues using the Gaussian–Hermite moments (GHMs) of local neighboring pixels. It is expected that the depth map obtained from GHMs provides robust features as compared to that provided by other popular depth maps such as those obtained from Kinect and defocus cue. We use the rich depth and intensity values of a pixel to score every point of a video frame for generating labeled probability maps in a 3D environment. These maps are then used to create a 3D scene wherein available objects are labeled distinctively. Experimental results reveal that our proposed approach yields excellent performance of object labeling for different multi-view scenes taken from RGB-D object dataset, in particular showing significant improvements in precision–recall characteristics and F1-score. DA - 2020/// PY - 2020/// DO - 10.1007/978-981-32-9291-8_8 VL - 1024 SP - 87-99 SN - 2194-5365 KW - Depth map KW - Object labeling KW - 3D scene ER - TY - JOUR TI - Fair and cache blocking aware warp scheduling for concurrent kernel execution on GPU AU - Zhao, Chen AU - Gao, Wu AU - Nie, Feiping AU - Wang, Fei AU - Zhou, Huiyang T2 - FUTURE GENERATION COMPUTER SYSTEMS-THE INTERNATIONAL JOURNAL OF ESCIENCE AB - With Graphic Processing Units (GPUs) being widely adopted in data centers to provide computing power, efficient support for GPU multitasking attracts significant attention. The prior GPU multitasking works include spatial multitasking and simultaneous multitasking (SMK). Spatial multitasking allocates GPU resources at the streaming multiprocessor (SM) granularity which is coarse-grained, and SMK runs concurrent kernels on the same SM, therefore is fine-grained. SMK is beneficial to improve GPU resource utilization especially when concurrent kernels have complementary characteristics. However, the main challenge for SMK is the interference among multiple kernels especially the contention on data cache. In this paper, we propose a fair and cache blocking aware warp scheduling (FCBWS) approach to ameliorate the contention on data cache and improve SMK on GPUs. In FCBWS, equal opportunity of issuing instructions is provided to each kernel, and memory pipeline stalls are tried to be avoided by predicting cache blocking. Kernels are extracted from various applications to construct concurrent kernel execution benchmarks. The simulation experiment results show that FCBWS outperforms previous multitasking methods; even compared to the state-of-the-art SMK method, FCBWS can improve system throughput (STP) by 10% on average and reduce average normalized turnaround time (ANTT) by 41% on average. DA - 2020/11// PY - 2020/11// DO - 10.1016/j.future.2020.05.023 VL - 112 SP - 1093-1105 SN - 1872-7115 KW - GPU KW - Concurrent kernels KW - Warp scheduling KW - Cache blocking KW - Interference ER - TY - JOUR TI - Effect of fabrication method on the structure and properties of a nanostructured nickel-free stainless steel AU - Heidari, L. AU - Tangestani, A. AU - Hadianfard, M. J. AU - Vashaee, D. AU - Tayebi, L. T2 - ADVANCED POWDER TECHNOLOGY AB - An ASTM F2581 nanostructured stainless steel was fabricated by two different powder metallurgy routes; Hot Powder Forging (HPF) and Binder Assisted Extrusion (BAE) methods. Their structure and mechanical properties were investigated and compared. In both fabrication methods, the alloy powder was made by using main alloying elements through mechanical alloying, along with the addition of a sintering aid. In the BAE method, a paste was prepared by mixing alloy powders with polymer followed by cold extrusion, polymer removal, and sintering. In the HPF method, the alloy powders were hot forged under high pressure. The structure and the size of the austenite crystallite of the samples were investigated by scanning electron microscopy (SEM), FE-SEM, x-ray diffraction (XRD) and transmission electron microscopy (TEM). It was determined that the samples prepared by the HPF method are generally denser than those made via BAE. The porosities are smaller and almost uniform in size and morphology in the HPF method. Furthermore, microhardness and tensile tests were performed on the samples. The results show that the ductility of BAE samples is higher than the HPF samples. The fracture surface of the BAE sample has deeper dimples, indicating higher ductility for BAE samples. On the other hand, both the hardness and strength of HPF samples are higher than those of the BAE samples. The results show that both methods produced specimens with considerably higher strength and hardness than conventional 316L stainless steel. DA - 2020/8// PY - 2020/8// DO - 10.1016/j.apt.2020.06.025 VL - 31 IS - 8 SP - 3408-3419 SN - 1568-5527 KW - Hot powder forging KW - Binder assisted extrusion KW - Nickel-free austenitic stainless steel KW - Powder metallurgy ER - TY - JOUR TI - Characterization of Limit State for Seismic Fragility Assessment of T-Joints in Piping System AU - Dubey, Ankit R. AU - Gupta, Abhinav AU - Cho, Sung Gook T2 - JOURNAL OF PRESSURE VESSEL TECHNOLOGY-TRANSACTIONS OF THE ASME AB - Abstract Fragility assessment requires characterization of a component or system's performance through a performance function/limit-state equation. The exceedance of limit-state is representative of failure or damage state. For the purposes of evaluating piping fragility, characterizing the behavior of T-joints through an appropriate performance function is critical, as failures in piping are generally localized at the location of T-joints, elbows, and nozzles. Past studies have utilized a monotonic rotation-based performance function. However, the existing criteria does not account for the effect of cyclic behavior. As observed during prior experimental studies, the T-joint behavior under cyclic loading is different from that under monotonic loading, and therefore, it is important to include the effects of cyclic behavior while characterizing a performance function. Moreover, the monotonic rotation-based performance function could not replicate all the leakage locations observed during experimental studies on a full-scale two-story piping system. Therefore, it is important to develop a new limit-state for accurate piping fragility assessment. This paper presents the development of a new limit state which considers the cyclic behavior of a T-joint and quantifies the number of cycles to failure. DA - 2020/10/1/ PY - 2020/10/1/ DO - 10.1115/1.4047041 VL - 142 IS - 5 SP - SN - 1528-8978 KW - seismic fragility KW - piping KW - threaded T-joint KW - limit-state ER - TY - JOUR TI - Localization of Biobotic Insects Using Low-Cost Inertial Measurement Units AU - Cole, Jeremy AU - Bozkurt, Alper AU - Lobaton, Edgar T2 - SENSORS AB - Disaster robotics is a growing field that is concerned with the design and development of robots for disaster response and disaster recovery. These robots assist first responders by performing tasks that are impractical or impossible for humans. Unfortunately, current disaster robots usually lack the maneuverability to efficiently traverse these areas, which often necessitate extreme navigational capabilities, such as centimeter-scale clearance. Recent work has shown that it is possible to control the locomotion of insects such as the Madagascar hissing cockroach (Gromphadorhina portentosa) through bioelectrical stimulation of their neuro-mechanical system. This provides access to a novel agent that can traverse areas that are inaccessible to traditional robots. In this paper, we present a data-driven inertial navigation system that is capable of localizing cockroaches in areas where GPS is not available. We pose the navigation problem as a two-point boundary-value problem where the goal is to reconstruct a cockroach’s trajectory between the starting and ending states, which are assumed to be known. We validated our technique using nine trials that were conducted in a circular arena using a biobotic agent equipped with a thorax-mounted, low-cost inertial measurement unit. Results show that we can achieve centimeter-level accuracy. This is accomplished by estimating the cockroach’s velocity—using regression models that have been trained to estimate the speed and heading from the inertial signals themselves—and solving an optimization problem so that the boundary-value constraints are satisfied. DA - 2020/8// PY - 2020/8// DO - 10.3390/s20164486 VL - 20 IS - 16 SP - SN - 1424-8220 UR - https://doi.org/10.3390/s20164486 KW - biobots KW - cyborg insects KW - inertial navigation KW - machine learning ER - TY - JOUR TI - Community Detection and Improved Detectability in Multiplex Networks AU - Huang, Yuming AU - Panahi, Ashkan AU - Krim, Hamid AU - Dai, Liyi T2 - IEEE TRANSACTIONS ON NETWORK SCIENCE AND ENGINEERING AB - We investigate the widely encountered problem of detecting communities in multiplex networks, such as social networks, with an unknown arbitrary heterogeneous structure. To improve detectability, we propose a generative model that leverages the multiplicity of a single community in multiple layers, with no prior assumption on the relation of communities among different layers. Our model relies on a novel idea of incorporating a large set of generic localized community label constraints across the layers, in conjunction with the celebrated Stochastic Block Model (SBM) in each layer. Accordingly, we build a probabilistic graphical model over the entire multiplex network by treating the constraints as Bayesian priors. We mathematically prove that these constraints/priors promote existence of identical communities across layers without introducing further correlation between individual communities. The constraints are further tailored to render a sparse graphical model and the numerically efficient Belief Propagation algorithm is subsequently employed. We further demonstrate by numerical experiments that in the presence of consistent communities between different layers, consistent communities are matched, and the detectability is improved over a single layer. We compare our model with a “correlated model” which exploits the prior knowledge of community correlation between layers. Similar detectability improvement is obtained under such a correlation, even though our model relies on much milder assumptions than the correlated model. Our model even shows a better detection performance over a certain correlation and signal to noise ratio (SNR) range. In the absence of community correlation, the correlation model naturally fails, while ours maintains its performance. DA - 2020/// PY - 2020/// DO - 10.1109/TNSE.2019.2949036 VL - 7 IS - 3 SP - 1697-1709 SN - 2327-4697 KW - Multiplexing KW - Stochastic processes KW - Belief propagation KW - Correlation KW - Periodic structures KW - Computational modeling KW - Bayes methods KW - Network theory (graphs) KW - graphical models KW - belief propagation ER - TY - JOUR TI - Prevention and Mitigation of Catastrophic Failures in Demand-Supply Interdependent Networks AU - Hosseinalipour, Seyyedali AU - Mao, Jiayu AU - Eun, Do Young AU - Dai, Huaiyu T2 - IEEE TRANSACTIONS ON NETWORK SCIENCE AND ENGINEERING AB - We propose a generic system model for a special category of interdependent networks, demand-supply networks, in which the demand and the supply nodes are associated with heterogeneous loads and resources, respectively. Our model sheds a light on a unique cascading failure mechanism induced by resource/load fluctuations, which in turn opens the door to conducting stress analysis on interdependent networks. Compared to the existing literature mainly concerned with the node connectivity, we focus on developing effective resource allocation methods to prevent these cascading failures from happening and to mitigate/confine them upon occurrence in the network. To prevent cascading failures, we identify some dangerous stress mechanisms, based on which we quantify the robustness of the network in terms of the resource configuration scheme. Afterward, we identify the optimal resource configuration under two resource/load fluctuations scenarios: uniform and proportional fluctuations. We further investigate the optimal resource configuration problem considering heterogeneous resource sharing costs among the nodes. To mitigate/confine ongoing cascading failures, we propose two network adaptations mechanisms: intentional failure and resource re-adjustment, based on which we propose an algorithm to mitigate an ongoing cascading failure while reinforcing the surviving network with a high robustness to avoid further failures. DA - 2020/// PY - 2020/// DO - 10.1109/TNSE.2019.2951084 VL - 7 IS - 3 SP - 1710-1723 SN - 2327-4697 KW - Power system faults KW - Power system protection KW - Robustness KW - Stress KW - Load modeling KW - Adaptation models KW - Resource management KW - Interdependent networks KW - demand-supply networks KW - robustness KW - resource and load fluctuations KW - cascading failures ER - TY - JOUR TI - Maximization of Robustness of Interdependent Networks Under Budget Constraints AU - Chattopadhyay, Srinjoy AU - Dai, Huaiyu AU - Eun, Do Young T2 - IEEE TRANSACTIONS ON NETWORK SCIENCE AND ENGINEERING AB - We consider the problem of interlink optimization in multilayer interdependent networks under cost constraints, with the objective of maximizing the robustness of the network against component (node) failures. Diverting from the popular approaches of branching process based analysis of the failure cascades or using a supra-adjacency matrix representation of the multilayer network and employing classical metrics, in this work, we present a surrogate metric based framework for constructing interlinks to maximize the network robustness. In particular, we focus on three representative mechanisms of failure propagation, namely, connected component based cascading failure, load distribution in interdependent networks, and connectivity in demand-supply networks, and propose metrics to track the network robustness for each of these mechanisms. Owing to their mathematical tractability, these metrics allow us to optimize the interlink structure to enhance robustness. Furthermore, we are able to introduce the cost of construction into the interlink design problem, a practical feature largely ignored in relevant literature. We simulate the failure cascades on real world networks to compare the performance of our interlinking strategies with the state of the art heuristics and demonstrate their effectiveness. DA - 2020/// PY - 2020/// DO - 10.1109/TNSE.2019.2935068 VL - 7 IS - 3 SP - 1441-1452 SN - 2327-4697 KW - Robustness KW - Measurement KW - Nonhomogeneous media KW - Mathematical model KW - Network topology KW - Optimization KW - Power system faults KW - Multilayer failure propagation KW - cost constrained optimization KW - network robustness KW - interdependent networks ER - TY - JOUR TI - Iron-on carbon nanotube (CNT) thin films for biosensing E-Textile applications AU - Li, Braden M. AU - Yildiz, Ozkan AU - Mills, Amanda C. AU - Flewwellin, Tashana J. AU - Bradford, Philip D. AU - Jur, Jesse S. T2 - CARBON AB - Conductive carbon nanotube-thermoplastic polyurethane (CNT-TPU) composite thin films are patterned and integrated onto knitted textile substrates to form electronic textile (E-Textile) dry electrodes. Vertically aligned CNT arrays are mechanically drawn into thin CNT sheets and infiltrated with a TPU solution to form the CNT-TPU thin films. The CNT-TPU thin films are then heat laminated onto knitted textile substrates to form dry E-Textile electrodes. To understand the wearability of our CNT-TPU thin films we perform an in-depth analysis of the films’ electromechanical properties, electrical impedance, and electrocardiogram (ECG) sensing performance. The electromechanical coupling between the CNT thin films and knitted textile substrates show a strong anisotropic dependence between the CNT film alignment and textile knit structure. Further analysis into the CNT thin films reveal that larger electrode sizes with a larger number of CNT sheet layers in the film, lead to more favorable impedance behaviors and ECG sensing capabilities. As a wearable demonstration, we fabricate a textile arm sleeve integrated with CNT thin film electrodes to form an ECG sensing E-Textile system. The proposed E-Textile sleeve demonstrates the practicality of our CNT thin films and show promise for other E-Textile and wearable applications. DA - 2020/10/30/ PY - 2020/10/30/ DO - 10.1016/j.carbon.2020.06.057 VL - 168 SP - 673-683 SN - 1873-3891 KW - E-Textiles KW - Electrocardiogram (ECG) KW - Composite materials KW - Carbon nanotubes KW - Biometric devices ER - TY - JOUR TI - Impact of Transients Caused by PV Transformer Energization on Active Industrial Loads AU - Chandel, Ayush AU - Lubkeman, David T2 - IETE TECHNICAL REVIEW AB - The importance and impact of transient studies with appropriate distribution system modelling is highlighted in the present work. New and realistic modelling techniques to be employed in modern distribution system are presented. Various issues, arising due to the energization of photovoltaic (PV) transformer on active industrial loads in a distribution network, are modelled. Sudden energization of large PV plant transformer(s) with respect to the voltage, current, harmonic profile and their effect on the system impedance in a distribution network is dealt with as this impacts the network performance. Cause and effect for the tripping of the industrial plant drives post connection of the large transformers of the photovoltaic plant is investigated. The inverter-based loads are sensitive to the frequency response of grids which is shaped by power factor capacitors. The use of current-limiting resistors and strict constraints on system impedance is analysed and inferred to be the promising techniques for the stable operation of large industrial loads. Furthermore, the research work highlights the various other aspects to make the distribution system more efficient. Special cautions need to be followed if industrial loads are in the vicinity of the planned DERs. Hence, the need of modelling and simulation of transient-impact studies with appropriate frequency analysis prior to actual deployment of large-scale PV plants in “vital” load areas is essential. DA - 2020/// PY - 2020/// DO - 10.1080/02564602.2020.1766386 KW - Active loads KW - conservation voltage reduction (CVR) KW - DER issues KW - inrush KW - passivity KW - system modelling KW - transient analysis KW - volt-var optimization (VVO) ER - TY - JOUR TI - A Systematic Literature Review of Animal-Assisted Interventions in Oncology (Part I): Methods and Results AU - Holder, Timothy R. N. AU - Gruen, Margaret E. AU - Roberts, David L. AU - Somers, Tamara AU - Bozkurt, Alper T2 - INTEGRATIVE CANCER THERAPIES AB - Animal-assisted interventions (AAIs) use human-animal interactions to positive effect in various contexts including cancer care. As the first installment of a 2-part series, this systematic literature review focuses on the research methods and quantitative results of AAI studies in oncology. We find methodological consistency in the use of canines as therapy animals, in the types of high-risk patients excluded from studies, and in the infection precautions taken with therapy animals throughout cancer wards. The investigated patient endpoints are not significantly affected by AAI, with the exceptions of improvements in oxygen consumption, quality of life, depression, mood, and satisfaction with therapy. The AAI field in oncology has progressed significantly since its inception and has great potential to positively affect future patient outcomes. To advance the field, future research should consistently improve the methodological design of studies, report data more completely, and focus more on the therapy animal’s well-being. DA - 2020/8// PY - 2020/8// DO - 10.1177/1534735420943278 VL - 19 SP - SN - 1552-695X KW - animal-assisted interventions KW - animal-assisted activities KW - animal-assisted therapy KW - oncology KW - cancer KW - human-animal bond KW - quantitative ER - TY - JOUR TI - Rheological Properties of Coordinated Physical Gelation and Chemical Crosslinking in Gelatin Methacryloyl (GelMA) Hydrogels AU - Young, Ashlyn T. AU - White, Olivia C. AU - Daniele, Michael A. T2 - MACROMOLECULAR BIOSCIENCE AB - Synthetically modified proteins, such as gelatin methacryloyl (GelMA), are growing in popularity for bioprinting and biofabrication. GelMA is a photocurable macromer that can rapidly form hydrogels, while also presenting bioactive peptide sequences for cellular adhesion and proliferation. The mechanical properties of GelMA are highly tunable by modifying the degree of substitution via synthesis conditions, though the effects of source material and thermal gelation have not been comprehensively characterized for lower concentration gels. Herein, the effects of animal source and processing sequence are investigated on scaffold mechanical properties. Hydrogels of 4-6 wt% are characterized. Depending on the temperature at crosslinking, the storage moduli for GelMA derived from pigs, cows, and cold-water fish range from 723 to 7340 Pa, 516 to 3484 Pa, and 294 to 464 Pa, respectively. The maximum storage moduli are achieved only by coordinated physical gelation and chemical crosslinking. In this method, the classic thermo-reversible gelation of gelatin occurs when GelMA is cooled below a thermal transition temperature, which is subsequently "locked in" by chemical crosslinking via photocuring. The effects of coordinated physical gelation and chemical crosslinking are demonstrated by precise photopatterning of cell-laden microstructures, inducing different cellular behavior depending on the selected mechanical properties of GelMA. DA - 2020/12// PY - 2020/12// DO - 10.1002/mabi.202000183 VL - 20 IS - 12 SP - SN - 1616-5195 KW - animal source KW - gelatin KW - gelatin methacryloyl KW - gelation KW - GelMA KW - mechanical properties KW - photopolymerization ER - TY - JOUR TI - Modeling of Mutually Coupled Switched Reluctance Motors Based on Net Flux Method AU - Mehta, Siddharth AU - Kabir, Md Ashfanoor AU - Husain, Iqbal AU - Pramod, Prerit T2 - IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS AB - Modeling and accurate estimation of mutual flux in switched reluctance motors are complex due to interphase flux interactions, magnetic saturation, and harmonics. The mutual flux contributes significantly toward torque production of mutually coupled switched reluctance motors (MCSRMs); therefore, their accurate modeling directly influences the control design. In this article, a net-flux-based machine model is proposed to model MCSRMs. The model utilizes dual-phase excitation and multiphase excitation methods to generate the flux lookup tables from the finite-element model of the MCSRM. The modeling process is simple, as it does not require the segregation of the self- and mutual flux components, and machine performance can be predicted accurately using the net flux. The proposed modeling method is validated by implementing it for a fully pitched and concentrated-wound MCSRM and evaluating accuracy against the finite-element method. Details of the developed model are presented along with its comparison with existing methods. A prototype of a fully pitched MCSRM has been built, and the model is validated experimentally. Results show that the proposed model has excellent accuracy even under saturated operating conditions. DA - 2020/// PY - 2020/// DO - 10.1109/TIA.2020.2968834 VL - 56 IS - 3 SP - 2451-2461 SN - 1939-9367 KW - Torque KW - Reluctance motors KW - Table lookup KW - Rotors KW - Computational modeling KW - Lookup table KW - machine modeling KW - mutual flux KW - mutually coupled switched reluctance motor (SRM) KW - torque prediction KW - torque ripple ER - TY - JOUR TI - Real-Time Stochastic Optimization of Energy Storage Management Using Deep Learning-Based Forecasts for Residential PV Applications AU - Hafiz, Faeza AU - Awal, M. A. AU - Queiroz, Anderson Rodrigo AU - Husain, Iqbal T2 - IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS AB - A computationally proficient real-time energy management method with stochastic optimization is presented for a residential photovoltaic (PV)-storage hybrid system comprised of a solar PV generation and a battery energy storage (BES). Existing offline energy management approaches for day-ahead scheduling of BES suffer from energy loss in real time due to the stochastic nature of load and solar generation. On the other hand, typical online algorithms do not offer optimal solutions for minimizing electricity purchase costs to the owners. To overcome these limitations, we propose an integrated energy management framework consisting of an offline optimization model concurrent with a real-time rule-based controller. The optimization is performed in receding horizon with load and solar generation forecast profiles using deep learning-based long short term memory method in rolling horizon to reduce the daily electricity purchase costs. The optimization model is formulated as a multistage stochastic program where we use the stochastic dual dynamic programming algorithm in the receding horizon to update the optimal set point for BES dispatch at a fixed interval. To prevent loss of energy during optimal solution update intervals, we introduce a rule-based controller underneath the optimization layer in finer time resolution at the power electronics converter control level. The proposed framework is evaluated using a real-time controller-hardware-in-the-loop test platform in an OPAL-RT simulator. The proposed real-time method is effective in reducing the net electricity purchase cost compared to other existing energy management methods. DA - 2020/// PY - 2020/// DO - 10.1109/TIA.2020.2968534 VL - 56 IS - 3 SP - 2216-2226 SN - 1939-9367 KW - Real-time systems KW - Energy management KW - Optimization KW - Solar power generation KW - Stochastic processes KW - Batteries KW - Deep learning KW - energy management KW - energy storage KW - load forecast KW - real-time control KW - stochastic programming ER - TY - JOUR TI - UAV-AIDED CELLULAR COMMUNICATIONS WITH DEEP REINFORCEMENT LEARNING AGAINST JAMMING AU - Lu, Xiaozhen AU - Xiao, Liang AU - Dai, Canhuang AU - Dai, Huaiyu T2 - IEEE WIRELESS COMMUNICATIONS AB - Cellular systems have to resist smart jammers that can optimize their selection of jamming channels and powers based on the estimated ongoing network states. In this article, we present an unmanned aerial vehicle (UAV) aided cellular framework against jamming, in which an UAV uses reinforcement learning to choose the relay policy for a mobile user whose serving base station is attacked by a jammer. More specifically, the UAV applies deep reinforcement learning and transfer learning to help cellular systems resist smart jamming without knowing the cellular topology, the message generation model, the server computation model and the jamming model, based on the previous anti-jamming relay experiences and the observed current communication status. The performance bound in terms of the bit error rate and the UAV energy consumption is derived from the Nash equilibrium of the studied dynamic relay game and verified via simulations. Simulation results show that this scheme can reduce the bit error rate and save the UAV energy consumption in comparison with the benchmark. DA - 2020/8// PY - 2020/8// DO - 10.1109/MWC.001.1900207 VL - 27 IS - 4 SP - 48-53 SN - 1558-0687 ER - TY - JOUR TI - Space-Shifted Wye-Delta Winding to Minimize Space Harmonics of Fractional-Slot Winding AU - Islam, M. D. Sariful AU - Kabir, Md Ashfanoor AU - Mikail, Rajib AU - Husain, Iqbal T2 - IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS AB - A space-shifted wye-delta winding for fractional-slot concentrated winding (FSCW) is proposed that can simultaneously cancel both sub- and super-order harmonics of its stator MMF. The new winding concept proposes two sets of three-phase windings by doubling the number of stator slots connected in the wye-delta configuration. These two winding sets are shifted in space with respect to each other and are connected in series. The wye-delta configuration eliminates subharmonics and enhances the torque-producing component, whereas their relative shifting angle eliminates the dominant higher order harmonics to provide a cleaner and enhanced MMF spectrum. In FSCW motors, dominant space harmonics other than the torque-producing component give rise to undesirable losses in the magnet and rotor core. The efficacy of the proposed method is demonstrated through its stator MMF, harmonic spectrum, and motor performance using finite-element analysis. The application of the proposed winding to a permanent magnet (PM) machine showed dominant sub- and super-order harmonics cancellation, total harmonic distortion reduction, and magnetic loss reduction along with torque density and power factor improvements. A prototype PM machine is built, and the performance of the proposed concept is verified experimentally. DA - 2020/// PY - 2020/// DO - 10.1109/TIA.2020.2975766 VL - 56 IS - 3 SP - 2520-2530 SN - 1939-9367 KW - Windings KW - Harmonic analysis KW - Stator windings KW - Torque KW - Power capacitors KW - Rotors KW - Efficiency KW - fractional-slot concentrated winding (FSCW) KW - harmonics KW - permanent magnet synchronous machine (PMSM) KW - power factor KW - stator MMF ER - TY - JOUR TI - Comparison of 2.3-kV 4H-SiC Accumulation-Channel Planar Power MOSFETs Fabricated With Linear, Square, Hexagonal, and Octagonal Cell Topologies AU - Agarwal, Aditi AU - Han, Kijeong AU - Baliga, B. J. T2 - IEEE TRANSACTIONS ON ELECTRON DEVICES AB - The performance of four cell topologies is compared for 2.3-kV 4H-SiC power MOSFETs fabricated in a commercial 6-in foundry. The devices were simultaneously manufactured with the same channel length (0.5 $ {\mu } \text{m}$ ), JFET width (1.1 $ {\mu } \text{m}$ ), and gate oxide thickness (55 nm) for comparison. In addition, an octagonal cell design with a JFET width of 1.5 $ {\mu } \text{m}$ was included for comparison. The square and hexagonal cell designs had the lowest specific ON-resistance, but their breakdown voltage was found to be reduced below 2.3 kV due to sharp cell corners. The smallest reverse transfer capacitance and gate charge were observed for the octagonal cell design with significantly larger (~5$\times $ ) values for the square and hexagonal designs. The high-frequency figure-of-merit HF-FOM[${R}_{\mathrm{\scriptscriptstyle ON}}{\ast } {C}_{\text {rss}}$ ] for the octagonal cell design was $3.5\times $ superior to the hexagonal and square cells and $1.5\times $ better than the linear cell. Its high-frequency figure-of-merit HF-FOM[${R}_{\mathrm{\scriptscriptstyle ON}} {\ast } {Q}_{\text {gd}}$ ] was $1.5\times $ superior to the hexagonal and square cells and $1.2\times $ better than the linear cell. This work demonstrates that the square and hexagonal cells are the best for low-frequency applications, whereas the octagonal cell design is the most suitable for achieving the best high-frequency performance of 2.3-kV 4H-SiC power MOSFETs. DA - 2020/// PY - 2020/// DO - 10.1109/TED.2020.3005632 VL - 67 IS - 9 SP - 3673-3678 SN - 1557-9646 KW - 4H-SiC KW - accumulation KW - cell topology KW - hexagonal KW - linear KW - MOSFET KW - octagonal KW - silicon carbide (SiC) KW - square ER - TY - JOUR TI - Optimization and Control of a Z-Source, Ultrafast Mechanically Switched, High-Efficiency DC Circuit Breaker AU - Mackey, Landon AU - Rachi, Md Rifat Kaisar AU - Peng, Chang AU - Husain, Iqbal T2 - IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS AB - A novel design of the Z-source circuit breaker topology is presented to minimize on-state losses of the protection device. An ultrafast mechanical switch is proposed to commutate the fault current and improve the controllability of the circuit breaker. Replacing the power thyristor in the Z-source circuit breaker and integrating an advanced control scheme reduces energy losses with a low-resistance mechanical contactor. The proposed design facilitates bidirectional current flow, enhances control capability for distributed energy resources, and improves ride-through capabilities during load transients. Z-source circuit breakers utilize an impedance network to create a forced current zero crossing in the event of a fault, allowing the inline thyristor to isolate the fault from the source through reverse bias. However, full load current flows through the thyristor, resulting in high loss and heat generation. The concept is validated, and a proper control scheme is developed for this circuit breaker through an analytical estimation model of the system dynamics during a fault. Simulation and modeling are performed in power systems computer aided design (PSCAD) and piecewise linear electrical circuit simulation (PLECS). Finally, an experimental laboratory prototype is tested to validate the analytical and simulation models and certify the control logic. DA - 2020/// PY - 2020/// DO - 10.1109/TIA.2020.2970657 VL - 56 IS - 3 SP - 2871-2879 SN - 1939-9367 KW - DC circuit breaker (DCCB) KW - power system protection KW - ultrafast mechanical switch (UFMS) KW - Z-source ER - TY - JOUR TI - Photoinduced reconfiguration to control the protein-binding affinity of azobenzene-cyclized peptides AU - Day, Kevin AU - Schneible, John D. AU - Young, Ashlyn T. AU - Pozdin, Vladimir A. AU - Driessche, George AU - Gaffney, Lewis A. AU - Prodromou, Raphael AU - Freytes, Donald O. AU - Fourches, Denis AU - Daniele, Michael AU - Menegatti, Stefano T2 - JOURNAL OF MATERIALS CHEMISTRY B AB - Light-controlled switching of cell-binding activity of fluorescently-labeled peptides for on-demand cell labeling. DA - 2020/9/7/ PY - 2020/9/7/ DO - 10.1039/d0tb01189d VL - 8 IS - 33 SP - 7413-7427 SN - 2050-7518 ER - TY - JOUR TI - What Does an Editor-in-Chief of IEEE Signal Processing Magazine Do, Anyway? [From the Editor] AU - Heath, R.W. T2 - IEEE Signal Processing Magazine AB - Reports on the role and responsibilities of the Editor-in-Chief of the IEEE Signaling Processing Magazine. DA - 2020/// PY - 2020/// DO - 10.1109/MSP.2020.2971121 VL - 37 IS - 2 SP - 3-4 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85080942350&partnerID=MN8TOARS ER - TY - JOUR TI - Spatial Channel Covariance Estimation for Hybrid Architectures Based on Tensor Decompositions AU - Park, Sungwoo AU - Ali, Anum AU - Gonzalez-Prelcic, Nuria AU - Heath, Robert W. T2 - IEEE Transactions on Wireless Communications AB - Spatial channel covariance information can replace full instantaneous channel state information for the analog precoder design in hybrid analog/digital architectures. Obtaining spatial channel covariance estimation, however, is challenging in the hybrid structure due to the use of fewer radio frequency (RF) chains than the number of antennas. In this paper, we propose a spatial channel covariance estimation method based on higher-order tensor decomposition for spatially sparse time-varying frequency-selective channels. The proposed method leverages the fact that the channel can be represented as a low-rank higher-order tensor. We also derive the Cramér-Rao lower bound on the estimation accuracy of the proposed method. Numerical results and theoretical analysis show that the proposed tensor-based approach achieves higher estimation accuracy in comparison with prior compressive-sensing-based approaches or conventional angle-of-arrival estimation approaches. DA - 2020/// PY - 2020/// DO - 10.1109/TWC.2019.2951135 VL - 19 IS - 2 SP - 1084-1097 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85079821667&partnerID=MN8TOARS KW - Tensor decomposition KW - spatial channel covariance KW - hybrid precoding KW - covariance estimation KW - millimeter wave ER - TY - JOUR TI - Revisiting Research on Signal Processing for Communications in a Pandemic [From the Editor] AU - Heath, R.W. T2 - IEEE Signal Processing Magazine AB - Presents the introductory editorial for this issue of the publication. DA - 2020/// PY - 2020/// DO - 10.1109/MSP.2020.2975306 VL - 37 IS - 3 SP - 3-5 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85084545450&partnerID=MN8TOARS ER - TY - JOUR TI - Adaptive Virtual Waveform Design for Millimeter-Wave Joint Communication-Radar AU - Kumari, P. AU - Vorobyov, S.A. AU - Heath, R.W. T2 - IEEE Transactions on Signal Processing AB - Joint communication and radar (JCR) waveforms with fully digital baseband generation and processing can now be realized at the millimeter-wave (mmWave) band. Prior work has proposed a mmWave wireless local area network (WLAN)-based JCR that exploits the WLAN preamble for radars. The performance of target velocity estimation, however, was limited. In this paper, we propose a virtual waveform design for an adaptive mmWave JCR. The proposed system transmits a few non-uniformly placed preambles to construct several receive virtual preambles for enhancing velocity estimation accuracy, at the cost of only a small reduction in the communication data rate. We evaluate JCR performance trade-offs using the Cramer-Rao Bound (CRB) metric for radar estimation and a novel distortion minimum mean square error (MMSE) metric for data communication. Additionally, we develop three different MMSE-based optimization problems for the adaptive JCR waveform design. Simulations show that an optimal virtual (non-uniform) waveform achieves a significant performance improvement as compared to a uniform waveform. For a radar CRB constrained optimization, the optimal radar range of operation and the optimal communication distortion MMSE (DMMSE) are improved. For a communication DMMSE constrained optimization with a high DMMSE constraint, the optimal radar CRB is enhanced. For a weighted MMSE average optimization, the advantage of the virtual waveform over the uniform waveform is increased with decreased communication weighting. Comparison of MMSE-based optimization with traditional virtual preamble count-based optimization indicated that the conventional solution converges to the MMSE-based one only for a small number of targets and a high signal-to-noise ratio. DA - 2020/// PY - 2020/// DO - 10.1109/TSP.2019.2956689 VL - 68 SP - 715-730 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85079812267&partnerID=MN8TOARS KW - Millimeter wave radar KW - millimeter wave communication KW - joint communication-radar KW - automotive applications KW - adaptive waveform design KW - velocity estimation ER - TY - JOUR TI - Submitting Columns and Forums to SPM [From the Editor] AU - Heath, R.W. T2 - IEEE Signal Processing Magazine AB - Reports on the process of submitting columns and forums to the publication and explains the content that is included therein. DA - 2020/// PY - 2020/// DO - 10.1109/MSP.2019.2952964 VL - 37 IS - 1 SP - 3-4 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85078531946&partnerID=MN8TOARS ER - TY - JOUR TI - Double-Sequence Frequency Synchronization for Wideband Millimeter-Wave Systems with Few-Bit ADCs AU - Zhu, D. AU - Bendlin, R. AU - Akoum, S. AU - Ghosh, A. AU - Heath, R.W. T2 - IEEE Transactions on Wireless Communications AB - In this paper, we propose and evaluate a novel double-sequence low-resolution frequency synchronization method in millimeter-wave (mmWave) systems. In our system model, the base station uses analog beams to send the synchronization signal with infinite-resolution digital-to-analog converters. The user equipment employs a fully digital front end to detect the synchronization signal with low-resolution analog-to-digital converters (ADCs). The key ingredient of the proposed method is the custom designed synchronization sequence pairs, from which there exists an invertible function (a ratio metric) of the carrier frequency offset (CFO) to be estimated. We use numerical examples to show that the ratio metric is robust to the quantization distortion. To implement our proposed method in practice, we propose to optimize the double-sequence design parameters such that: (i) for each individual user, the impact of the quantization distortion on the CFO estimation accuracy is minimized, and (ii) the resulting frequency range of estimation can capture as many users' CFOs as possible. Numerical results reveal that our proposed algorithm can provide a flexible means to estimate CFO in a variety of low-resolution settings. DA - 2020/// PY - 2020/// DO - 10.1109/TWC.2019.2953263 VL - 19 IS - 2 SP - 1357-1372 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85079767034&partnerID=MN8TOARS KW - Synchronization KW - Frequency synchronization KW - Estimation KW - OFDM KW - Quantization (signal) KW - Distortion KW - 3GPP KW - Low-resolution analog-to-digital converter (ADC) KW - millimeter-wave (mmWave) KW - frequency synchronization KW - 5G KW - sequence design ER - TY - JOUR TI - Guest Editorial: Special Section on Resilience, Reliability, and Security in Cyber-Physical Systems AU - Zhang, Bin AU - Zhang, Peng AU - Vu, Tuyen AU - Chow, Mo-Yuen T2 - IEEE TRANSACTIONS ON INDUSTRIAL INFORMATICS AB - Cyber-physical systems (CPS) refers to the integrative system consisting of interconnected computing and control devices interacting with the physical infrastructure via sensors and actuators. Recently, there is a swift growth of CPSs ranging from smart grids to smart buildings, robotics, and other industrial control systems. They have formed the keystone of the sustainable growth of the economy, manufacturing, and smart and connected communities. Due to extensive applications of CPSs, their resilience, reliability, and security are paramount. Many factors, however, pose significant threats to CPSs and lead to high economic losses and social impacts. Software defects also make CPSs vulnerable to security attacks and coordinated cyber and physical attacks. To address this issue, emerging technologies and methods for understanding and improving the resilience, reliability, and security of CPSs are needed. This Special Section aims to provide a platform to help define, understand, and quantify the resilience, reliability, and security of CPSs. DA - 2020/7// PY - 2020/7// DO - 10.1109/TII.2020.2971725 VL - 16 IS - 7 SP - 4865-4867 SN - 1941-0050 ER - TY - JOUR TI - Device quality templates of InxGa1-xN (x < 0.1) with defect densities comparable to GaN AU - Routh, Evyn L. AU - Abdelhamid, Mostafa AU - El-Masry, N. A. AU - Bedair, S. M. T2 - APPLIED PHYSICS LETTERS AB - InGaN/GaN multiple quantum well (MQW) structures currently used in optical devices are based on highly strained InGaN films. The presence of strain reduces quantum efficiency and indium incorporation, two critical parameters in addressing the green gap. We report on the growth of InGaN-relaxed templates on GaN as substrates to reduce the strain in the MQW structures. Relaxation in the InGaN templates, due to the lattice mismatch, is accommodated by the generation of V-pits rather than the formation of misfit dislocations. InxGa1−xN templates (x ∼ 0.1) are grown via a modified semibulk (SB) approach, with a gradually increasing GaN interlayer thickness to provide a mechanism for backfilling of V-pits. We used high-resolution x-ray diffraction rocking curves to quantify the edge-type and screw-type dislocation density present in the SB and compared the results with the etch pit density obtained via atomic force microscopy after treating the SB with a silane etch. Device-quality InGaN templates with defect density in the mid 108 cm−2 were investigated using the above two approaches, with a quality comparable to state-of-the-art GaN. DA - 2020/8/3/ PY - 2020/8/3/ DO - 10.1063/5.0015419 VL - 117 IS - 5 SP - SN - 1077-3118 ER - TY - JOUR TI - Improving Controllability and Plug-and-Play Operation of Wind Farms Using B2B Converters AU - Sadamoto, Tomonori AU - Chakrabortty, Aranya T2 - IEEE CONTROL SYSTEMS LETTERS AB - We show that a critical factor deciding the controllability of a doubly fed induction generator (DFIG) in a wind power system is the ratio of its leakage reactance to resistance. If this ratio is high then the DFIG has two uncontrollable slow resonant modes. In that situation any type of control action for attenuating disturbances inside the wind farm becomes impossible. In order to prevent this uncontrollability, we propose to add a back-to-back (B2B) converter in the stator line of the DFIG. This new converter has two benefits: 1) it improves the controllability of the wind farm significantly and 2) its signal-flow diagram reveals a cascade structure where the grid is shown to impact the DFIG dynamics, but not vice versa. The cascade structure also enables one to design controllers for regulating the DFIG currents and its dc-link voltages in a completely modular and plug-and-play fashion. We illustrate various implementation aspects of this control mechanisms via numerical simulations of the IEEE 68-bus power system model with one wind farm. DA - 2020/4// PY - 2020/4// DO - 10.1109/LCSYS.2019.2931822 VL - 4 IS - 2 SP - 379-384 SN - 2475-1456 KW - Doubly fed induction generators KW - Controllability KW - Wind farms KW - Power system stability KW - Stators KW - Rotors KW - Eigenvalues and eigenfunctions KW - DFIG KW - stability KW - controllability KW - plug-and-play control KW - wind power ER - TY - JOUR TI - Multiuser Precoding for Sum-Rate Maximization in Relay-Aided mmWave Communications AU - Yalcin, Ahmet Zahid AU - Yapici, Yavuz T2 - IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY AB - Relay-aided transmission is envisioned as a key strategy to combat severe path loss and link blockages emerging as unique challenges in millimeter-wave (mmWave) communications. This work considers a relay-aided multiuser mmWave communications scenario aiming at maximizing the sum rate through optimal transmit and relay precoder design. We propose a novel joint precoder design strategy, which exploits weighted minimum mean-square error (WMMSE) using its equivalency to sum-rate maximization. We obtain closed form expressions of transmit and relay precoders, and propose to compute them through alternating-optimization iterations without having to resort to complicated numerical optimization techniques. Numerical results verify the superiority of the proposed precoding strategy as compared to conventional precoding schemes. DA - 2020/6// PY - 2020/6// DO - 10.1109/TVT.2020.2987473 VL - 69 IS - 6 SP - 6808-6812 SN - 1939-9359 KW - Relays KW - Receivers KW - Optimization KW - Precoding KW - MIMO communication KW - Unicast KW - Mean square error methods KW - Amplify-and-forward (AF) relaying KW - convex optimization KW - sum rate KW - minimum mean-square error (MMSE) ER - TY - JOUR TI - Microphysiological systems for the modeling of wound healing and evaluation of pro-healing therapies AU - Deal, Halston E. AU - Brown, Ashley C. AU - Daniele, Michael A. T2 - JOURNAL OF MATERIALS CHEMISTRY B AB - Wound healing microphysiological systems have been engineered with synthetic and natural materials and techniques such as bioprinting or viscous finger patterning. Model designs focus on particular phases of wound healing or the recapitulation of micro-anatomies. DA - 2020/8/28/ PY - 2020/8/28/ DO - 10.1039/d0tb00544d VL - 8 IS - 32 SP - 7062-7075 SN - 2050-7518 ER - TY - JOUR TI - Wideband Air-to-Ground Channel Characterization for Multiple Propagation Environments AU - Cui, Zhuangzhuang AU - Briso-Rodriguez, Cesar AU - Guan, Ke AU - Guvenc, Ismail AU - Zhong, Zhangdui T2 - IEEE Antennas and Wireless Propagation Letters AB - Air-to-ground (AG) communications have attracted much attention for future advanced wireless communications. Unmanned aerial vehicle, as a critical enabler in AG communications, can be operated in various environments, such as over-water, hilly, and built-up environments. A better understanding of radio channels in various scenarios can immensely facilitate the deployment and design of wireless systems. Thus, in this letter, wideband characterizations of AG channels are performed based on the multienvironment channel measurements, where the center frequency is set to 6.5 GHz with the bandwidth of 500 MHz, which provides high delay resolution to capture significant multipath. Two key channel parameters, Rician K-factor and root-mean-square (rms) delay spread, are used as metrics to characterize AG channels. The positive Rician K-factor indicates the line-of-sight (LOS)-dominated characteristic of the AG channel. The discrepancy of the rms delay spread shows the obvious influence of multipaths from building on channel delay characteristics. DA - 2020/9// PY - 2020/9// DO - 10.1109/LAWP.2020.3012889 VL - 19 IS - 9 SP - 1634-1638 UR - https://doi.org/10.1109/LAWP.2020.3012889 KW - Delays KW - Antenna measurements KW - Rician channels KW - Sea measurements KW - Unmanned aerial vehicles KW - Frequency measurement KW - Wideband KW - Air-to-ground (AG) KW - channel characterization KW - channel measurements KW - delay spread KW - multipath KW - unmanned aerial vehicle (UAV) KW - ultrawideband (UWB) ER - TY - JOUR TI - Infection Analysis on Irregular Networks Through Graph Signal Processing AU - Hosseinalipour, Seyyedali AU - Wang, Jie AU - Tian, Yuanzhe AU - Dai, Huaiyu T2 - IEEE Transactions on Network Science and Engineering AB - In a networked system, functionality can be seriously endangered when nodes are infected, due to internal random failures or a contagious virus that develops into an epidemic. Given a snapshot of the network representing the nodes' states (infected or healthy), infection analysis refers to distinguishing an epidemic from random failures and gathering information for effective countermeasure design. This analysis is challenging due to irregular network structure, heterogeneous epidemic spreading, and noisy observations. This paper treats a network snapshot as a graph signal, and develops effective approaches for infection analysis based on graph signal processing. For the macro (network-level) analysis aiming to distinguish an epidemic from random failures, 1) multiple detection metrics are defined based on the graph Fourier transform (GFT) and neighborhood characteristics of the graph signal; 2) a new class of graph wavelets, distance-based graph wavelets (DBGWs), are developed; and 3) a machine learning-based framework is designed employing either the GFT spectrum or the graph wavelet coefficients as features for infection analysis. DBGWs also enable the micro (node-level) infection analysis, through which the performance of epidemic countermeasures can be improved. Extensive simulations are conducted to demonstrate the effectiveness of all the proposed algorithms in various network settings. DA - 2020/7/1/ PY - 2020/7/1/ DO - 10.1109/TNSE.2019.2958892 UR - https://doi.org/10.1109/TNSE.2019.2958892 KW - Epidemics KW - Signal processing algorithms KW - Wavelet transforms KW - Signal processing KW - Viruses (medical) KW - Wavelet analysis KW - Social networking (online) KW - Epidemic spreading KW - graph fourier transform KW - graph signal processing KW - graph wavelets KW - infection analysis ER - TY - JOUR TI - Nano-hydroxyapatite and nano-hydroxyapatite/zinc oxide scaffold for bone tissue engineering application AU - Heidari, Fatemeh AU - Bazargan-Lari, Reza AU - Razavi, Mehdi AU - Fahimipour, Farahnaz AU - Vashaee, Daryoosh AU - Tayebi, Lobat T2 - INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY AB - Abstract This research aims to evaluate the mechanical properties, biocompatibility, and degradation behavior of scaffolds made of pure hydroxyapatite (HA) and HA‐modified by ZnO for bone tissue engineering applications. HA and ZnO were developed using sol‐gel and precipitation methods respectively. The scaffolds properties were characterized using X‐ray diffraction (XRD), Fourier transform spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), atomic absorption (AA), and atomic force microscopy (AFM). The interaction of scaffold with cells was assessed using in vitro cell proliferation and alkaline phosphatase (ALP) assays. The obtained results indicate that the HA/ZnO scaffolds possess higher compressive strength, fracture toughness, and density—but lower hardness—when compared to the pure HA scaffolds. After immersing the scaffold in the SBF solution, more deposited apatite appeared on the HA/ZnO, which results in the rougher surface on this scaffold compared to the pure HA scaffold. Finally, the in vitro biological analysis using human osteoblast cells reveals that scaffolds are biocompatible with adequate ALP activity. DA - 2020/11// PY - 2020/11// DO - 10.1111/ijac.13596 VL - 17 IS - 6 SP - 2752-2761 SN - 1744-7402 KW - bioceramics KW - bone KW - nanomaterials ER - TY - JOUR TI - Exploring Convolution Neural Network for Branch Prediction AU - Mao, Yonghua AU - Zhou, Huiyang AU - Gui, Xiaolin AU - Shen, Junjie T2 - IEEE Access AB - Recently, there have been significant advances in deep neural networks (DNNs) and they have shown distinctive performance in speech recognition, natural language processing, and image recognition. In this paper, we explore DNNs to push the limit for branch prediction. We treat branch prediction as a classification problem and employ both deep convolutional neural networks (CNNs), ranging from LeNet to ResNet-50, and deep belief network (DBN) for branch prediction. We compare the effectiveness of DNNs with the state-of-the-art branch predictors, including the perceptron, our prior work, Multi-poTAGE+SC, and MTAGE+SC branch predictors. The last two are the most recent winners of championship branch prediction (CBP) contests. Several interesting observations emerged from our study. First, for branch prediction, the DNNs outperform the perceptron model as high as 60-80%. Second, we analyze the impact of the depth of CNNs (i.e., number of convolutional layers and pooling layers) on the misprediction rates. The results confirm that deeper CNN structures can lead to lower misprediction rates. Third, the DBN could outperform our prior work, but not outperform the state-of-the-art TAGE-like branch predictor; the ResNet-50 could not only outperform our prior work, but also the Multi-poTAGE+SC and MTAGE+SC. DA - 2020/// PY - 2020/// DO - 10.1109/ACCESS.2020.3017196 VL - 8 SP - 152008-152016 UR - https://doi.org/10.1109/ACCESS.2020.3017196 KW - History KW - Neural networks KW - Machine learning KW - Convolution KW - Predictive models KW - Prediction algorithms KW - Correlation KW - Branch prediction KW - CNN KW - deep learning KW - VGG KW - ResNet ER - TY - JOUR TI - Leveraging Sensing at the Infrastructure for mmWave Communication AU - Ali, Anum AU - Gonzalez-Prelcic, Nuria AU - Heath, Robert W. AU - Ghosh, Amitava T2 - IEEE COMMUNICATIONS MAGAZINE AB - V2X communication in the mmWave band is one way to achieve high data rates for applications like infotainment, cooperative perception, augmented reality assisted driving, and so on. MmWave communication relies on large antenna arrays, and configuring these arrays poses high training overhead. In this article, we motivate the use of infrastructure mounted sensors (which will be part of future smart cities) to aid establishing and maintaining mmWave vehicular communication links. We provide numerical and measurement results to demonstrate that information from these infrastructure sensors reduces the mmWave array configuration overhead. Finally, we outline future research directions to help materialize the use of infrastructure sensors for mmWave communication. DA - 2020/7// PY - 2020/7// DO - 10.1109/MCOM.001.1900700 VL - 58 IS - 7 SP - 84-89 SN - 1558-1896 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85089539802&partnerID=MN8TOARS KW - Intelligent sensors KW - Radar KW - Radar antennas KW - Roads KW - Millimeter wave communication KW - Antenna arrays ER - TY - JOUR TI - Spin wave generation via localized spin-orbit torque in an antiferromagnet-topological insulator heterostructure AU - Xu, Xinyi AU - Semenov, Yuriy G. AU - Kim, Ki Wook T2 - JOURNAL OF APPLIED PHYSICS AB - The spin–orbit torque induced by a topological insulator (TI) is theoretically examined for spin wave generation in a neighboring antiferromagnetic thin film. The investigation is based on the micromagnetic simulation of Néel vector dynamics and the analysis of transport properties in the TI. The results clearly illustrate that propagating spin waves can be achieved in the antiferromagnetic thin-film strip through localized excitation, traveling over a long distance. The oscillation amplitude gradually decays due to the non-zero damping as the Néel vector precesses around the magnetic easy axis with a fixed frequency. The frequency is also found to be tunable via the strength of the driving electrical current density. While both the bulk and the surface states of the TI contribute to induce the effective torque, the calculation indicates that the surface current plays a dominant role over the bulk counterpart except in the heavily degenerate cases. Compared to the more commonly applied heavy metals, the use of a TI can substantially reduce the threshold current density to overcome the magnetic anisotropy, making it an efficient choice for spin wave generation. The Néel vector dynamics in the nano-oscillator geometry are examined as well. DA - 2020/7/28/ PY - 2020/7/28/ DO - 10.1063/5.0010478 VL - 128 IS - 4 SP - SN - 1089-7550 ER - TY - JOUR TI - Comparison of the Effectiveness of Online Homework With Handwritten Homework in Electrical and Computer Engineering Classes AU - Trussell, H. Joel AU - Gumpertz, Marcia L. T2 - IEEE TRANSACTIONS ON EDUCATION AB - Contribution: This article compares the predictive performance of the scores on WeBWorK homework (online) with those of standard handwritten homework. The comparison is done across six undergraduate electrical engineering classes where each of the nine instructors have used both homework modalities. Background: Online homework systems have been used for many years, but analysis of their effectiveness is mixed. Previous work has been limited to a small number of classes in a wide variety of disciplines. This article has a larger number of classes and instructors than previous studies. The classes cover many basic topic areas in electrical and computer engineering, so is directly applicable to the audience of these transactions. Research Question: What is the effect of online homework compared to traditional handwritten homework on the performance of the students on the final exams in selected ECE classes? Methodology: Mixed-effects analysis of variance models are used to determine the predictive ability of performance on homework of the two modalities on the performance on the final exams. The data are limited to classes where the instructors have taught the class using both modalities. These models incorporate the effect of modalities for each instructor and the effect of the modalities across all classes. Findings: The result is that there is no significant statistical difference in the two modalities to predict final exam scores. This indicates that the advantages of using the automated online system can be obtained with no detrimental effect on the students' learning. DA - 2020/8// PY - 2020/8// DO - 10.1109/TE.2020.2971198 VL - 63 IS - 3 SP - 209-215 SN - 1557-9638 KW - Electronic mail KW - Software KW - Education KW - Standards KW - Electrical engineering KW - Testing KW - Programming KW - Effectiveness KW - handwritten homework KW - online homework KW - statistical analysis KW - traditional homework KW - WeBWorK ER - TY - JOUR TI - Compact W-Band "Swan Neck" Turnstile Junction Orthomode Transducer Implemented by 3-D Printing AU - Shen, Junyu AU - Ricketts, David S. T2 - IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES AB - A turnstile junction orthomode transducer (OMT) provides polarization separation/combining on a full waveguide bandwidth; however, it bears a complex connecting structure, which accordingly leads to a bulky volume. We present a compact W-band (75-110 GHz) OMT using a “swan neck” twist for the connection between a turnstile junction and an E-plane Y-junction, for minimizing the overall OMT structure. The core volume for the proposed OMT is 9× less than the previously reported stacked-layer OMT. The compact W-band OMT was built by digital light processing (DLP) 3-D printing technology and was postmetallized by silver electroless plating. The return loss of the vertical-polarized port (V-port) and the horizontal-polarized port (H-port) is characterized, as averagely 17 and 15 dB, respectively. The measured average insertion loss from H- and V-ports to the common port is 0.5 and 0.6 dB. The measured isolation between V- and H-ports is averagely 28 dB. Furthermore, the turnstile junction asymmetry along the central axis was revealed in computed tomography (CT) scanned images. The simulation shows a negative effect of the asymmetric structure on the OMT isolation. In addition, the dual-polarized (dual-pol) antenna combining such OMT and a corrugated horn was realized in a compact size. The cross-polarization level of the OMT, characterized in a far-field test of this dual-pol antenna, is averagely -18 dB at the W-band. DA - 2020/8// PY - 2020/8// DO - 10.1109/TMTT.2020.2992065 VL - 68 IS - 8 SP - 3408-3417 SN - 1557-9670 KW - Dual-polarized antenna KW - orthomode transducer (OMT) KW - 3-D printing KW - turnstile junction KW - W-band KW - waveguide ER - TY - JOUR TI - A mm-Sized Free-Floating Wireless Implantable Opto-Electro Stimulation Device AU - Jia, Yaoyao AU - Gong, Yan AU - Weber, Arthur AU - Li, Wen AU - Ghovanloo, Maysam T2 - MICROMACHINES AB - Towards a distributed neural interface, consisting of multiple miniaturized implants, for interfacing with large-scale neuronal ensembles over large brain areas, this paper presents a mm-sized free-floating wirelessly-powered implantable opto-electro stimulation (FF-WIOS2) device equipped with 16-ch optical and 4-ch electrical stimulation for reconfigurable neuromodulation. The FF-WIOS2 is wirelessly powered and controlled through a 3-coil inductive link at 60 MHz. The FF-WIOS2 receives stimulation parameters via on-off keying (OOK) while sending its rectified voltage information to an external headstage for closed-loop power control (CLPC) via load-shift-keying (LSK). The FF-WIOS2 system-on-chip (SoC), fabricated in a 0.35-µm standard CMOS process, employs switched-capacitor-based stimulation (SCS) architecture to provide large instantaneous current needed for surpassing the optical stimulation threshold. The SCS charger charges an off-chip capacitor up to 5 V at 37% efficiency. At the onset of stimulation, the capacitor delivers charge with peak current in 1.7-12 mA range to a micro-LED (µLED) array for optical stimulation or 100-700 μA range to a micro-electrode array (MEA) for biphasic electrical stimulation. Active and passive charge balancing circuits are activated in electrical stimulation mode to ensure stimulation safety. In vivo experiments conducted on three anesthetized rats verified the efficacy of the two stimulation mechanisms. The proposed FF-WIOS2 is potentially a reconfigurable tool for performing untethered neuromodulation. DA - 2020/6// PY - 2020/6// DO - 10.3390/mi11060621 VL - 11 IS - 6 SP - SN - 2072-666X KW - free-floating implants KW - inductive link KW - switched-capacitor-based optical KW - electrical stimulation KW - charge balancing ER - TY - JOUR TI - Enhancing Short Circuit Capability of 1.2-kV Si IGBT Using a Gate-Source Shorted Si Depletion Mode MOSFET in Series With the Emitter AU - Kanale, Ajit AU - Baliga, B. Jayant T2 - IEEE TRANSACTIONS ON POWER ELECTRONICS AB - Short-circuit (SC) capability is a critical requirement for power switches in modern power electronics applications. A tradeoff between on-state voltage drop, switching loss, and SC capability of insulated gate bipolar transistors (IGBTs) is performed by manufacturers. In general, IGBTs optimized with low on-state voltage have poor SC capability compared with those with good SC capability. In this report, a novel method is described to improve the SC capability of IGBTs optimized with low on-state voltage drop by using a gate-source-shorted Si depletion-mode (DM) mosfet connected in series with the emitter. A seven-fold increase in the SC capability of commercially available 1.2-kV IGBTs was achieved at high dc bus voltages with minimal impact on on-state and switching loss performance. The proposed method also provides a sensing voltage signal at the drain of the Si DM-mosfet, which can be used to monitor the on-state current magnitude and to detect SC fault conditions. DA - 2020/6// PY - 2020/6// DO - 10.1109/TPEL.2019.2953589 VL - 35 IS - 6 SP - 6350-6361 SN - 1941-0107 KW - Fault detection KW - insulated gate bipolar transistor (IGBT) KW - power MOSFET KW - power semiconductor switches KW - robustness ER - TY - JOUR TI - Low-Resolution Limited-Feedback NOMA for mmWave Communications AU - Yapici, Yavuz AU - Guvenc, Ismail AU - Dai, Huaiyu T2 - IEEE Transactions on Wireless Communications AB - The spectrum-efficient millimeter-wave (mmWave) communications has recently attracted much attention as a viable solution to spectrum crunch problem. In this work, we propose a novel non-orthogonal multiple access (NOMA) framework, which makes use of the directional propagation characteristics of mmWave communications so as to improve the spectral efficiency through non-orthogonal signaling. In particular, we consider one-bit quantized angle information as a limited yet effective feedback scheme describing the channel quality of user equipment (UE) in mmWave bands. The UE pairs for NOMA transmission are then established using not only the one-bit distance feedback as a classical approach, but also the one-bit angle feedback. The proposed strategy is therefore referred to as two-bit NOMA. We also propose a novel hybrid strategy, called combined NOMA, for the circumstances with no UE pair through two-bit NOMA. Whenever no UE pair is available through any NOMA strategy, we resort to single user transmission (SUT) with proper UE selection schemes. The hybrid outage sum-rate performance is also analyzed thoroughly with the respective outage and rate expressions. The numerical results verify that the proposed strategy outperforms one-bit NOMA schemes with either angle- or distance-only feedback, and has a very close outage sum-rate performance to that for the optimal full-resolution feedback. DA - 2020/8// PY - 2020/8// DO - 10.1109/TWC.2020.2993212 VL - 19 IS - 8 SP - 5433-5446 UR - https://doi.org/10.1109/TWC.2020.2993212 KW - NOMA KW - Decoding KW - Signal to noise ratio KW - Wireless communication KW - Downlink KW - Array signal processing KW - Encoding KW - Low-resolution limited-feedback KW - millimeter-wave (mmWave) communications KW - multiuser communications KW - non-orthogonal multiple access (NOMA) ER - TY - JOUR TI - Analysis and Design Considerations of a Contactless Magnetic Plug for Charging Electric Vehicles Directly From the Medium-Voltage DC Grid With Arc Flash Mitigation AU - Beddingfield, Richard B. AU - Samanta, Suvendu AU - Nations, Mark S. AU - Wong, Isaac AU - Ohodnicki, Paul R. AU - Bhattacharya, Subhashish T2 - IEEE Journal of Emerging and Selected Topics in Industrial Electronics AB - Electric vehicle charging has shifted to higher voltages to achieve higher power for more rapid charging capabilities. This article provides a contactless magnetic plug solution that enables medium-voltage grid connections for electric vehicle charging to achieve 3.5-kVDC-to-400-VDC, 150-kW rapid charging capabilities. This novel magnetic plug improves upon existing electric vehicle charging solutions by guaranteeing safe operation and connection through galvanic and physical separation from the medium-voltage side. It achieves this with a gap and barrier in the transformer core. We introduce a unique asymmetry in the core to localize parasitic capacitance, fully separating the medium- and low-voltage regions. This approach eliminates arcing risk and allows rapid charging capabilities to be delivered to the general public. This gapped core constitutes the plug action of our proposed charging system. We present solutions for the unique challenges of this solution through a detailed analysis of the magnetic design. We confirm this analysis in finite-element analysis and experimentation. The solution is verified through a scaled laboratory prototype of 20 kW, 1 kVDC to 50 VDC that is representative of the proposed 150-kW design. We demonstrate safe, arc-free, disconnection in included active content, a new solution for high-power electric vehicle rapid charging. DA - 2020/7// PY - 2020/7// DO - 10.1109/JESTIE.2020.2999589 VL - 1 IS - 1 SP - 3-13 UR - https://doi.org/10.1109/JESTIE.2020.2999589 ER - TY - JOUR TI - Toward a High-Throughput Wireless Smart Arena for Behavioral Experiments on Small Animals AU - Mirbozorgi, S. Abdollah AU - Jia, Yaoyao AU - Zhang, Pengcheng AU - Ghovanloo, Maysam T2 - IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING AB - This work presents a high-throughput and scalable wirelessly-powered smart arena for behavioral experiments made of multiple EnerCage Homecage (HC) systems, operating in parallel in a way that they can fit in standard racks that are commonly used in animal facilities. The proposed system, which is referred to as the multi-EnerCage-HC (mEHC), increases the volume of data that can be collected from more animal subjects, while lowering the cost and duration of experiments as well as stress-induced bias by minimizing the involvement of human operators. Thus improving the quality, reproducibility, and statistical power of experiment outcomes, while saving precious lab space. The system is equipped with an auto-tuning mechanism to compensate for the resonance frequency shifts caused by the dynamic nature of the mutual inductance between adjacent homecages. A functional prototype of the mEHC system has been implemented with 7 units and analyzed for theoretical design considerations that would minimize the effects of interference and resonance frequency bifurcation. Experiment results demonstrate robust wireless power and data transmissions capabilities of this system within the noisy lab environment. DA - 2020/// PY - 2020/// DO - 10.1109/TBME.2019.2961297 VL - 67 IS - 8 SP - 2359-2369 SN - 1558-2531 KW - Animals KW - Resonant frequency KW - Wireless communication KW - Resonators KW - Bifurcation KW - Mutual coupling KW - Standards KW - Inductive wireless power transmission KW - high-throughput experiments KW - bifurcation KW - behavioral neuroscience ER - TY - JOUR TI - Chitosan Hydrogels for Synergistic Delivery of Chemotherapeutics to Triple Negative Breast Cancer Cells and Spheroids AU - Schneible, John D. AU - Young, Ashlyn T. AU - Daniele, M. A. AU - Menegatti, S. T2 - PHARMACEUTICAL RESEARCH AB - This study aimed to develop a hydrogel system for treating aggressive triple negative breast cancer (TNBC) via kinetically-controlled delivery of the synergistic drug pair doxorubicin (DOX) and gemcitabine (GEM). A 2D assay was adopted to evaluate therapeutic efficacy by determining combination index (CI), and a 3D assay using cancer spheroids was implemented to assess the potential for translation in vivo. The release of DOX and GEM from an acetylated-chitosan (ACS, degree of acetylation χAc = 40 ± 5%) was characterized to identify a combined drug loading that affords release kinetics and dose that are therapeutically synergistic. The selected DOX/GEM-ACS formulation was evaluated in vitro with 2-D and 3-D models of TNBC to determine the combination index (CI) and the tumor volume reduction, respectively. Therapeutically desired release dosages and kinetics of GEM and DOX were achieved. When evaluated with a 2-D model of TNBC, the hydrogel afforded a CI of 0.14, indicating a stronger synergism than concurrent administration of DOX and GEM (CI = 0.23). Finally, the therapeutic hydrogel accomplished a notable volume reduction of the cancer spheroids (up to 30%), whereas the corresponding dosages of free drugs only reduced growth rate. The ACS hydrogel delivery system accomplishes drug release kinetics and molar ratio that affords strong therapeutically synergism. These results, in combination with the choice of ACS as affordable and highly abundant source material, provide a strong pre-clinical demonstration of the potential of the proposed system for complementing surgical resection of aggressive solid tumors. DA - 2020/// PY - 2020/// DO - 10.1007/s11095-020-02864-2 VL - 37 IS - 7 ER - TY - JOUR TI - Preliminary Evaluation of a Wearable Sensor System for Heart Rate Assessment in Guide Dog Puppies AU - Foster, Marc AU - Brugarolas, Rita AU - Walker, Katherine AU - Mealin, Sean AU - Cleghern, Zach AU - Yuschak, Sherrie AU - Clark, Julia Condit AU - Adin, Darcy AU - Russenberger, Jane AU - Gruen, Margaret AU - Sherman, Barbara L. AU - Roberts, David L. AU - Bozkurt, Alper T2 - IEEE SENSORS JOURNAL AB - This paper details the development of a novel wireless heart rate sensing system for puppies in training as guide dogs. The system includes a harness with on-board electrocardiography (ECG) front-end circuit, inertial measurement unit and a micro-computer with wireless capability where the major research focus of this paper was on the ergonomic design and evaluation of the system on puppies. The first phase of our evaluation was performed on a Labrador Retriever between 12 to 26 weeks in age as a pilot study. The longitudinal weekly data collected revealed the expected trend of a decreasing average heart rate and increased heart rate variability as the age increased. In the second phase, we improved the system ergonomics for a larger scale deployment in a guide dog school (Guiding Eyes for the Blind (Guiding Eyes)) on seventy 7.5-week-old puppies (heart rate coverage average of 86.7%). The acquired ECG based heart rate data was used to predict the performance of puppies in Guiding Eyes's temperament test. We used the data as an input to a machine learning model which predicted two Behavior Checklist (BCL) scores as determined by expert Guiding Eyes puppy evaluators with an accuracy above 90%. DA - 2020/// PY - 2020/// DO - 10.1109/JSEN.2020.2986159 VL - 20 IS - 16 SP - 9449-9459 SN - 1558-1748 UR - https://doi.org/10.1109/JSEN.2020.2986159 KW - ECG KW - heart rate variability KW - electrodes KW - machine learning KW - 3D printing KW - wearable ER - TY - JOUR TI - The Case for Domain-Specialized Branch Predictors for Graph-Processing AU - Samara, Ahmed AU - Tuck, James T2 - IEEE COMPUTER ARCHITECTURE LETTERS AB - Branch prediction is believed by many to be a solved problem, with state-of-the-art predictors achieving near-perfect prediction for many programs. In this article, we conduct a detailed simulation of graph-processing workloads in the GAPBS benchmark suite and show that branch mispredictions occur frequently and are still a large limitation on performance in key graph-processing applications. We provide a detailed analysis of which branches are mispredicting and show that a few key branches are the main source of performance degradation across the graph-processing benchmarks we looked at. We also propose a few ideas for future work to improve branch prediction accuracy on graph workloads. DA - 2020/// PY - 2020/// DO - 10.1109/LCA.2020.3005895 VL - 19 IS - 2 SP - 101-104 SN - 1556-6064 KW - Graph-processing KW - branch prediction ER - TY - JOUR TI - Past, Present, and Future of Affinity-based Cell Separation Technologies AU - Bacon, Kaitlyn AU - Lavoie, Ashton AU - Rao, Balaji M. AU - Daniele, Michael AU - Menegatti, Stefano T2 - ACTA BIOMATERIALIA AB - Progress in cell purification technology is critical to increase the availability of viable cells for therapeutic, diagnostic, and research applications. A variety of techniques are now available for cell separation, ranging from non-affinity methods such as density gradient centrifugation, dielectrophoresis, and filtration, to affinity methods such as chromatography, two-phase partitioning, and magnetic-/fluorescence-assisted cell sorting. For clinical and analytical procedures that require highly purified cells, the choice of cell purification method is crucial, since every method offers a different balance between yield, purity, and bioactivity of the cell product. For most applications, the requisite purity is only achievable through affinity methods, owing to the high target specificity that they grant. In this review, we discuss past and current methods for developing cell-targeting affinity ligands and their application in cell purification, along with the benefits and challenges associated with different purification formats. We further present new technologies, like stimuli-responsive ligands and parallelized microfluidic devices, towards improving the viability and throughput of cell products for tissue engineering and regenerative medicine. Our comparative analysis provides guidance in the multifarious landscape of cell separation techniques and highlights new technologies that are poised to play a key role in the future of cell purification in clinical settings and the biotech industry. STATEMENT OF SIGNIFICANCE: Technologies for cell purification have served science, medicine, and industrial biotechnology and biomanufacturing for decades. This review presents a comprehensive survey of this field by highlighting the scope and relevance of all known methods for cell isolation, old and new alike. The first section covers the main classes of target cells and compares traditional non-affinity and affinity-based purification techniques, focusing on established ligands and chromatographic formats. The second section presents an excursus of affinity-based pseudo-chromatographic and non-chromatographic technologies, especially focusing on magnetic-activated cell sorting (MACS) and fluorescence-activated cell sorting (FACS). Finally, the third section presents an overview of new technologies and emerging trends, highlighting how the progress in chemical, material, and microfluidic sciences has opened new exciting avenues towards high-throughput and high-purity cell isolation processes. This review is designed to guide scientists and engineers in their choice of suitable cell purification techniques for research or bioprocessing needs. DA - 2020/8// PY - 2020/8// DO - 10.1016/j.actbio.2020.05.004 VL - 112 SP - 29-51 SN - 1878-7568 KW - Cell purification KW - Immunoaffinity KW - MACS KW - FACS KW - Microfluidics ER - TY - JOUR TI - Magnon and spin transition contribution in heat capacity of ferromagnetic Cr-doped MnTe: Experimental evidence for a paramagnetic spin-caloritronic effect AU - Polash, Md Mobarak Hossain AU - Rasoulianboroujeni, Morteza AU - Vashaee, Daryoosh T2 - Applied Physics Letters AB - We present experimental evidence for the simultaneous existence of the magnons and spin-state transition contributions to the heat capacity in ferromagnetic (FM) Cr-doped MnTe (Tc~280K), where the magnon heat capacity is attributed to the observed magnon-bipolar carrier-drag thermopower. The pristine antiferromagnetic (AFM) MnTe shows only a magnon-induced peak in the heat capacity near the Neel temperature, TN~307K. However, Cr-doped MnTe shows a magnon-contributed heat capacity peak at ~293K with an additional peak in the deep paramagnetic domain near 780K. Temperature-dependent magnetic susceptibility reveals that Cr-doping initially creates low-spin (LS) states Mn2+ ions into MnTe near and below TN due to a higher crystal field induced by Cr ions. Above 400K, LS Mn2+ ions start converting into high-spin (HS) Mn2+ ions. The LS-to-HS transition of Mn2+ leads to an excess entropy and hence excess heat capacity contribution in the system. Temperature-dependent X-ray diffraction (XRD) and magnetic field-dependent susceptibility (M-H) confirmed no presence of any structural changes and magnetic polaron, respectively. Both XRD and M-H ensure that the peak of the heat capacity in the paramagnetic domain is originated solely by the spin-state transition. The heat capacity versus temperature was calculated to explain the contribution of each component, including the ones due to the phonons, magnons, spin-transition, Schottky anomaly, and lattice dilation. With the recent advances in spin-caloritronics extending the spin-based effects from magnetic to paramagnetic materials, the data from the heat capacity can play a crucial role to probe the presence of different phenomena such as paramagnon-carrier-drag and spin-entropy thermopowers. DA - 2020/7/27/ PY - 2020/7/27/ DO - 10.1063/5.0011887 UR - https://doi.org/10.1063/5.0011887 ER - TY - JOUR TI - A critical evaluation of grid stability and codes, energy storage and smart loads in power systems with wind generation AU - Al Kez, Dlzar AU - Foley, Aoife M. AU - McIlwaine, Neil AU - Morrow, D. John AU - Hayes, Barry P. AU - Zehir, M. Alparslan AU - Mehigan, Laura AU - Papari, Behnaz AU - Edrington, Chris S. AU - Baran, Mesut T2 - ENERGY AB - Existing power systems are facing new challenges in maintaining the security of the power system as the penetration of variable renewable energy technologies, such as variable speed wind turbines, increase. System non-synchronous generation replaces conventional generators as penetration of renewable generation increases. This affects system rotational inertia and limits the number of online thermal generators that can provide frequency stability services and system-wide areas voltage stability. This evolution has resulted in some changes to existing grid codes and new ancillary services. Furthermore, it could provide opportunities to address the security of the system utilizing modern smart technologies, e.g. smart loads, heat pumps and electric vehicles. The aim of this paper is to evaluate the impacts of large-scale renewable power generation on power system dynamics from the perspective of the power system operator. It focuses on the grid codes implications and challenges specifically. Synthetic inertia response opportunities from smart loads, electric vehicles and energy storage technologies and dispatching wind farms during frequency excursions are analyzed and thoroughly discussed. The key finding is that rethinking in the development of grid code requirements and market mechanisms are needed if a power system based on 100% power electronic renewable generation is to be achieved. This type of power system would need a range of technologies to provide the types of ancillary (i.e. system) services required, as none of the technologies alone can tackle all the challenges presented. DA - 2020/8/15/ PY - 2020/8/15/ DO - 10.1016/j.energy.2020.117671 VL - 205 SP - SN - 1873-6785 KW - Dynamic impact KW - Grid codes KW - Fast frequency response KW - Wind energy KW - Battery energy storage KW - Rate of change of frequency ER - TY - JOUR TI - The Bloch Electron Response to Electric Fields: Application to Graphene AU - Iafrate, Gerald AU - Sokolov, Valeriy T2 - PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS AB - The theory of Bloch electron dynamics for carriers in homogeneous electric fields of arbitrary time dependence is developed in consideration of the electronic transport properties in graphene. The general approach is to use the accelerated Bloch state representation (ABR) as a basis so that the dependence upon the electric field, including Zener tunneling, is treated exactly; also, the electric field is described in the vector potential gauge. Within the ABR, the instantaneous eigenstates for the central Hamiltonian are described and utilized to develop both the time‐dependent wave functions and the single‐particle density matrix pictures with explicit application to intrinsic graphene. The Bloch electron analysis for graphene in a constant electric field reveals the explicit manifestation of electron–hole pair creation, Bloch oscillations, and Wannier–Stark localization. The average velocity and acceleration are established as an explicit function of the electric field, and their behavior is characterized on short and long time scales. Further, it is shown that the average acceleration in a nonvanishing electric field gives rise to an electric field induced dynamical effective mass tensor in the direction of the field. DA - 2020/6// PY - 2020/6// DO - 10.1002/pssb.201900660 VL - 257 IS - 6 SP - SN - 1521-3951 KW - Bloch electron dynamics KW - graphene KW - quantum transport KW - time-dependent homogeneous electric fields ER - TY - JOUR TI - Efficient Control of Stochastic Switching via Spin Pumping in Antiferromagnetic Structures AU - Semenov, Yuriy G. AU - Kim, Ki Wook T2 - PHYSICAL REVIEW APPLIED AB - Electrically controlled switching in an antiferromagnet (AFM), utilizing a currentless mechanism, is theoretically examined at finite temperatures. The structure consists of a metallic AFM with biaxial magnetic anisotropy sandwiched between a ferromagnetic spin filter and a semiconductor Schottky junction in a two-terminal pillar configuration. The calculations show that the torque necessary for the desired ${90}^{\ensuremath{\circ}}$ rotation of the N\'eel vector between two easy axes can be provided efficiently by pumping spin-polarized electrons into and out of the AFM through the metallic ferromagnetic layer. Consideration of thermal fluctuations illustrates the stochastic nature of the switching, whose probability distribution can be tailored by the electrical signal pulse as well as by the device dimensions. Detection of the N\'eel-vector state following this rotation may also be achieved straightforwardly via the large anisotropic magnetoresistance of the biaxial antiferromagnetic material. These properties, along with an ultrafast switching speed and a low energy requirement, are expected to be well suited for applications in nonvolatile memory and probabilistic computing. DA - 2020/6/26/ PY - 2020/6/26/ DO - 10.1103/PhysRevApplied.13.064065 VL - 13 IS - 6 SP - SN - 2331-7019 ER - TY - JOUR TI - An Approach Towards Extreme Fast Charging Station Power Delivery for Electric Vehicles with Partial Power Processing AU - Iyer, Vishnu Mahadeva AU - Gulur, Srinivas AU - Gohil, Ghanshyamsinh AU - Bhattacharya, Subhashish T2 - IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS AB - This article proposes an approach for realizing the power delivery scheme for an extreme fast charging (XFC) station that is meant to simultaneously charge multiple electric vehicles (EVs). A cascaded H-bridge converter is utilized to directly interface with the medium voltage grid while dual-active-bridge based soft-switched solid-state transformers are used to achieve galvanic isolation. The proposed approach eliminates redundant power conversion by making use of partial power rated dc-dc converters to charge the individual EVs. Partial power processing enables independent charging control over each EV, while processing only a fraction of the total battery charging power. Practical implementation schemes for the partial power charger unit are analyzed. A phase-shifted full-bridge converter-based charger is proposed. Design and control considerations for enabling multiple charging points are elucidated. Experimental results from a down-scaled laboratory test-bed are provided to validate the control aspects, functionality, and effectiveness of the proposed XFC station power delivery scheme. With a down-scaled partial power converter that is rated to handle only 27% of the battery power, an efficiency improvement of 0.6% at full-load and 1.6% at 50% load is demonstrated. DA - 2020/// PY - 2020/// DO - 10.1109/TIE.2019.2945264 VL - 67 IS - 10 SP - 8076-8087 SN - 1557-9948 UR - https://doi.org/10.1109/TIE.2019.2945264 KW - Cascaded H-bridge (CHB) converter KW - dc fast charger KW - dc-dc power converters KW - dual active bridge (DAB) KW - energy storage KW - fast charging station KW - partial power processing KW - phase-shifted full-bridge (PSFB) KW - solid-state transformer (SST) ER - TY - JOUR TI - A Rotating Restart Method for Scalar (v/f) Controlled Synchronous Reluctance Machine Drives Using a Single DC-Link Current Sensor AU - Lee, Kibok AU - Kim, Heonyoung AU - Lukic, Srdjan M. T2 - IEEE ACCESS AB - This paper presents a rotating restart method for v/f scalar controlled Synchronous Reluctance Machines (SynRMs) using a single DC-link current sensor. In such a case, the initial rotor position and speed are required to restart the machine due to the absence of a position sensor. The method proposes to inject three active voltage vectors in the stationary reference frame to induce the phase currents required for estimating the rotor position and speed. In addition, the phase current reconstruction method is proposed to reduce the distortion of the measured phase currents caused by adopting a single DC-link current sensor and to consequently enhance the rotor position estimation accuracy. With the proposed method, the appropriate voltage vector can be applied to the machine, thus minimizing the inrush current during the restart. Furthermore, the proposed method only requires the machine parameters on the nameplate, and it does not require any additional machine-specific tuning processes. This paper proposes a simple restart method suitable for scalar-controlled SynRM drives with a single DC-link current sensor. The effectiveness of the proposed restart scheme is validated through the simulation and experimental results. DA - 2020/// PY - 2020/// DO - 10.1109/ACCESS.2020.3000220 VL - 8 SP - 106629-106638 SN - 2169-3536 KW - Synchronous reluctance motor (SynRM) KW - restart method KW - rotor position and speed estimation KW - scalar (V/f) control KW - single DC-link current sensor ER - TY - JOUR TI - A CM Filter Configuration for Grid-Tied Voltage Source Converters AU - Gulur, Srinivas AU - Iyer, Vishnu Mahadeva AU - Bhattacharya, Subhashish T2 - IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS AB - Common mode (CM) filters play a crucial role in determining adherence to conducted emissions (CE) standards for grid-tied voltage source converters. Design and implementation of such filters can be challenging since they depend on several factors like identification of CM noise paths, fidelity of passive components and discerning the frequency and amplitude of CM noise sources. In this article, a CM filter has been proposed, which uses passive components along with the converter's heat sink as a circulating return path for the CM currents. Based on the presented CM circuit models with the proposed filter, a detailed design process has been delineated for selecting the passive components required to realize the CM filter. Additionally, the heat-sink potential has been shown to be touch safe during both ideal and nonideal grid conditions with the proposed CM filter. CE spectral results measured using a commercially procured line impedance stabilization network and captured time domain converter operational wave forms for a 2-level, 3π grid-tied voltage source converter validate the functionality and effectiveness of the presented design. DA - 2020/// PY - 2020/// DO - 10.1109/TIE.2019.2949530 VL - 67 IS - 10 SP - 8100-8111 SN - 1557-9948 UR - https://doi.org/10.1109/TIE.2019.2949530 KW - Common mode (CM) noise KW - CM filter KW - differential mode (DM) noise KW - DM filter KW - electromagnetic interference (EMI) KW - electromagnetic compatibility (EMC) KW - heat sink KW - voltage source inverter KW - voltage source rectifier ER - TY - JOUR TI - Capacitor Voltage Balancing for Neutral Point Clamped Dual Active Bridge Converters AU - Awal, M. A. AU - Bipu, Md Rashed Hassan AU - Montes, Oscar Andres AU - Feng, Hao AU - Husain, Iqbal AU - Yu, Wensong AU - Lukic, Srdjan T2 - IEEE TRANSACTIONS ON POWER ELECTRONICS AB - A capacitor voltage balancing method is proposed for a full-bridge neutral point diode clamped (NPC) dual-active bridge (DAB) converter. In existing literature, capacitor voltage balancing is achieved by actively selecting between the small voltage vectors, i.e., connecting either the upper or the lower capacitor on the dc bus to the transformer winding, on the basis of measured voltage mismatch. These balancing methods are dependent on the direction of power flow through the DAB converter. In this work, we propose a voltage balancing controller, which is independent of power flow direction and does not require adjustments of active voltage vectors through the modulator. Irrespective of the direction of transformer current, by dynamically shifting the switching instants of the inner switch pairs in the two NPC legs during the free-wheeling/zero voltage vector time, either of the two capacitors can be selectively charged without introducing any offsets in the voltage-second seen by the transformer. A simple bidirectional phase-shift modulator is designed to facilitate voltage balancing irrespective of power flow direction or mode of operation. The proposed method is highly and universally effective under any converter operating condition and was verified and demonstrated through analysis, simulation, and hardware experiments using a laboratory prototype. DA - 2020/// PY - 2020/// DO - 10.1109/TPEL.2020.2988272 VL - 35 IS - 10 SP - 11267-11276 SN - 1941-0107 KW - Capacitors KW - Switches KW - Bridge circuits KW - Voltage control KW - Topology KW - Voltage measurement KW - Legged locomotion KW - Capacitor voltage balancing KW - dual active bridge (DAB) KW - neutral point diode clamped (NPC) KW - neutral point balancing ER - TY - JOUR TI - Influence of the order of fabrication sequences on the thermoelectric properties of skutterudite CoSb3–Cu0.6Ni0.4 nanocomposites T2 - Journal of Alloys and Compounds AB - Nanocomposite samples of CoSb3-xCu0.6Ni0.4 (x = 1, 3.5, 6, and 9 wt%) were fabricated through two different approaches to understand the influence of fabrication processes on the thermoelectric properties of CoSb3 skutterudite. CoSb3 matrix and Cu0.6Ni0.4 nanoalloy were synthesized separately via hydrothermal procedures. The mixtures of as-hydrothermally synthesized powders were prepared and annealed in the first method, while in the second fabrication route, CoSb3 powders were initially annealed, followed by mixing with Cu0.6Ni0.4 and annealing of the composite at the same conditions. The results showed improved electrical conductivity of CoSb3 compounds, which is consistent with the systematic increase of the carrier concentration upon increasing the Cu0.6Ni0.4 content. The grain boundary potential barrier mechanism was used to describe the influence of Cu0.6Ni0.4 nanoalloy on the height of the energy barrier of CoSb3-xCu0.6Ni0.4, as compared with that of pristine CoSb3 synthesized using the similar hydrothermal method. The onset of bipolar thermopower reduction is shifted to higher temperatures; however, the room temperature thermopower is reduced upon increasing the content of Cu0.6Ni0.4 nanoinclusions. The sample containing 1 wt% of Cu0.6Ni0.4 fabricated through the first fabrication procedure showed the highest zT value at ∼550 K. DA - 2020/12// PY - 2020/12// DO - 10.1016/j.jallcom.2020.156188 UR - http://dx.doi.org/10.1016/j.jallcom.2020.156188 KW - Hydrothermal synthesis KW - Cu0.6Ni0.4 nano alloy KW - Cobalt skutterudite KW - Fabrication sequences KW - Nanocomposite KW - Thermoelectric properties KW - Bipolar effect ER - TY - JOUR TI - A Monolithically Integrated Racetrack Colliding-Pulse Mode-Locked Laser With Pulse-Picking Modulator AU - Bhardwaj, Ashish AU - Bustos-Ramirez, Ricardo AU - Hoefler, Gloria E. AU - Dentai, Andrew AU - Plascak, Michael E. AU - Kish, Fred AU - Delfyett, Peter J. AU - Wu, Ming C. T2 - IEEE JOURNAL OF QUANTUM ELECTRONICS AB - We present a novel photonic integrated circuit (PIC) that monolithically integrates a racetrack colliding-pulse mode-locked laser with a pulse-picking electro-absorption modulator and a semiconductor optical amplifier on Indium Phosphide. We present detailed characterization of this PIC that includes optical pulse characterization, phase noise and long term stability under passive and hybrid mode-locking conditions. Allan deviation measurements made on the optical pulse train from the PIC show a fractional frequency instability of 8 × 10 -11 at 1 second and follow a 1/τ trend. We also demonstrate repetition rate reduction from ~10 GHz to ~500 MHz with an extinction ratio of ~14.65 dB using an on-chip pulse-picking electro-absorption modulator. DA - 2020/8// PY - 2020/8// DO - 10.1109/JQE.2020.2994990 VL - 56 IS - 4 SP - SN - 1558-1713 KW - Optical pulses KW - Semiconductor optical amplifiers KW - Laser mode locking KW - Integrated optics KW - Modulation KW - Optical pulse compression KW - Laser mode-locking KW - photonic integrated circuits ER - TY - JOUR TI - Model-Free Reinforcement Learning of Minimal-Cost Variance Control AU - Jing, Gangshan AU - Bai, He AU - George, Jemin AU - Chakrabortty, Aranya T2 - IEEE CONTROL SYSTEMS LETTERS AB - This letter proposes two reinforcement learning (RL) algorithms for solving a class of coupled algebraic Riccati equations (CARE) for linear stochastic dynamic systems with unknown state and input matrices. The CARE are formulated for a minimal-cost variance (MCV) control problem that aims to minimize the variance of a cost function while keeping its mean at an acceptable range using a noisy infinite-horizon full-state feedback linear quadratic regulator (LQR). We propose two RL algorithms where the input matrix can be estimated at the very first iteration. This, in turn, frees up significant amount of computational complexity in the intermediate steps of the learning phase by avoiding repeated matrix inversion of a high-dimensional data matrix. The overall complexity is shown to be less than RL for both stochastic and deterministic LQR. Additionally, the disturbance noise entering the model is not required to satisfy any condition for ensuring efficiency of either RL algorithms. Simulation examples are presented to illustrate the effectiveness of the two designs. DA - 2020/10// PY - 2020/10// DO - 10.1109/LCSYS.2020.2995547 VL - 4 IS - 4 SP - 916-921 SN - 2475-1456 KW - Mathematical model KW - Heuristic algorithms KW - Stochastic processes KW - Iterative methods KW - Riccati equations KW - Computational complexity KW - Optimal control KW - Reinforcement learning KW - stochastic dynamic systems KW - variance control KW - coupled Riccati equations ER - TY - JOUR TI - Guest Editorial Special Issue on Selected Papers From the IEEE Sensors Conference 2018 AU - Dahiya, Ravinder AU - Oralkan, Omer AU - Pratap, Rudra T2 - IEEE SENSORS JOURNAL AB - Since its inception in 2002, the IEEE Sensors Conference has come a long way in establishing itself as a premier conference in the world on sensors and sensing technologies. With the entire world moving rapidly toward a ubiquitous intelligence society, the emphasis on deployment of trillions of sensors in the near future is driving the world of sensor technology like never before. It is reflected in the rapidly increasing research and development activities on sensors throughout the world today. The IEEE Sensors Council has done a remarkable job in promoting this area and providing a consistent platform for sharing and dissemination of knowledge related to all aspects of sensing and sensor development among researchers, manufacturers, and the users of sensors. The idea of holding the IEEE Sensors Conference in different parts of the world actively supports this promotion over different geographies. It could not have been more timely to hold SENSORS 2018, for the first time, in one of the largest and fastest developing economies of the world - India. The 2018 edition of the Sensors Conference was held on October 28–31 in New Delhi — the capital city of India that has been inhabited for six thousand years and has seen a great many upheavals in history. DA - 2020/7/1/ PY - 2020/7/1/ DO - 10.1109/JSEN.2020.2984165 VL - 20 IS - 13 SP - 6792-6793 SN - 1558-1748 ER - TY - JOUR TI - Gene Regulatory Network Inference: Connecting Plant Biology and Mathematical Modeling AU - Broeck, Lisa AU - Gordon, Max AU - Inze, Dirk AU - Williams, Cranos AU - Sozzani, Rosangela T2 - FRONTIERS IN GENETICS AB - Plant responses to environmental and intrinsic signals are tightly controlled by multiple transcription factors (TFs). These TFs and their regulatory connections form gene regulatory networks (GRNs), which provide a blueprint of the transcriptional regulations underlying plant development and environmental responses. This review provides examples of experimental methodologies commonly used to identify regulatory interactions and generate GRNs. Additionally, this review describes network inference techniques that leverage gene expression data to predict regulatory interactions. These computational and experimental methodologies yield complex networks that can identify new regulatory interactions, driving novel hypotheses. Biological properties that contribute to the complexity of GRNs are also described in this review. These include network topology, network size, transient binding of TFs to DNA, and competition between multiple upstream regulators. Finally, this review highlights the potential of machine learning approaches to leverage gene expression data to predict phenotypic outputs. DA - 2020/5/25/ PY - 2020/5/25/ DO - 10.3389/fgene.2020.00457 VL - 11 SP - SN - 1664-8021 KW - gene regulatory network KW - network properties KW - network inference KW - machine learning KW - experimental methodologies ER - TY - JOUR TI - Applications of Hard and Soft Tissue Engineering in Dentistry AU - Tahriri, Mohammadreza AU - Torres, Regine AU - Karkazis, Emelia AU - Karkazis, Alexander AU - Bader, Rizwan AU - Vashaee, Daryoosh AU - Tayebi, Lobat T2 - APPLICATIONS OF BIOMEDICAL ENGINEERING IN DENTISTRY DA - 2020/// PY - 2020/// DO - 10.1007/978-3-030-21583-5_8 SP - 179-193 ER - TY - JOUR TI - Physical-Layer Assisted Secure Offloading in Mobile-Edge Computing AU - He, Xiaofan AU - Jin, Richeng AU - Dai, Huaiyu T2 - IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS AB - The wireless offloading feature of the recently advocated mobile-edge computing (MEC) imposes a risk of disclosing private user data to eavesdroppers. Physical-layer security approaches that are built on information theoretic methods can be applied to defend eavesdropping in MEC. Nonetheless, directly incorporating existing physical-layer security technique may introduce extra energy and delay costs to the resource-limited mobile device and thus substantially disrupt the users' offloading decisions. To fulfill effective secure offloading in MEC, there is a compelling need to properly optimize existing physical-layer security techniques and develop new offloading schemes accordingly. With this consideration, a novel physical-layer assisted secure offloading scheme is proposed in this work, in which the edge server proactively broadcasts jamming signals to impede eavesdropping and leverages full-duplex communication technique to effectively suppress the self-interference. Finding the optimal jamming signal and the corresponding optimal offloading ratio turns out to be a challenging bilevel optimization problem. The special structure of the secure offloading problem is exploited to develop efficient offloading algorithms. Numerical results are presented to validate the effectiveness of the proposed scheme. DA - 2020/6// PY - 2020/6// DO - 10.1109/TWC.2020.2979456 VL - 19 IS - 6 SP - 4054-4066 SN - 1558-2248 KW - Servers KW - Jamming KW - Security KW - Mobile handsets KW - Wireless communication KW - Task analysis KW - Interference cancellation KW - Mobile-edge computing KW - secure offloading KW - physical-layer ER - TY - JOUR TI - Tunable 0.7-2.8-GHz Reflection-Mode N-Path Filters in 45-nm SOI CMOS AU - Bonner-Stewart, Jeffrey AU - Wilson, Charley, III AU - Floyd, Brian A. T2 - IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES AB - This article presents the principles of operation of a reflection-mode N-path filter and then discusses both single-balanced and double-balanced implementations. The single-balanced approach can be used to realize tunable filters with extremely low insertion loss; however, the circuit also exhibits harmonic responses. The double-balanced reflector naturally rejects even-order harmonics and can be modified to cancel the third harmonics as well to provide a tunable N-path filter with the second through fourth harmonics rejected. This comes at the expense of increased insertion loss to support the required balun circuitry used to balance the mixers. Prototypes for both types of filters have been realized in the 45-nm SOI CMOS technology. Measurements on the single-balanced reflection-mode filter indicate 0.8-2.4-dB insertion loss across a 700-3000-MHz tuning range. The input-referred 1-dB compression point is 0 dBm and the input-referred third-order intercept point (IIP3) is +10-dBm in-band and +22-dBm out-of-band (OOB), and the circuit consumes 2.5-7.2 mW of power. Measurements on the double-balanced reflection-mode filter indicate 1.9-4.4-dB insertion loss across a 700-2800-MHz tuning range. The input-referred 1-dB compression point is +0.75 dBm, and IIP3 is >+16.3-dBm in-band and >+19.5-dBm OOB, and the circuit consumes a total of 4.0-15.6 mW of power. DA - 2020/6// PY - 2020/6// DO - 10.1109/TMTT.2020.2971489 VL - 68 IS - 6 SP - 2343-2357 SN - 1557-9670 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85086269923&partnerID=MN8TOARS KW - Harmonic cancellation KW - N-path reflection mode KW - SOI KW - transversal filter KW - tunable filter ER - TY - JOUR TI - A Modern 16-QAM Digital Radio You Can Design and Build at Home [Application Notes] AU - Ricketts, David S. T2 - IEEE MICROWAVE MAGAZINE AB - Reports on how to design and build a modern, 16-QAM digital radio. DA - 2020/7// PY - 2020/7// DO - 10.1109/MMM.2020.2985192 VL - 21 IS - 7 SP - 10-22 SN - 1557-9581 KW - Quadrature amplitude modulation KW - Radio communication KW - Dipole antennas KW - Power transmission KW - Design methodology KW - RF signals KW - Receivers KW - Radio frequency ER - TY - JOUR TI - Dynamic and scalable DNA-based information storage AU - Lin, Kevin N. AU - Volkel, Kevin AU - Tuck, James M. AU - Keung, Albert J. T2 - NATURE COMMUNICATIONS AB - Abstract The physical architectures of information storage systems often dictate how information is encoded, databases are organized, and files are accessed. Here we show that a simple architecture comprised of a T7 promoter and a single-stranded overhang domain (ss-dsDNA), can unlock dynamic DNA-based information storage with powerful capabilities and advantages. The overhang provides a physical address for accessing specific DNA strands as well as implementing a range of in-storage file operations. It increases theoretical storage densities and capacities by expanding the encodable sequence space and simplifies the computational burden in designing sets of orthogonal file addresses. Meanwhile, the T7 promoter enables repeatable information access by transcribing information from DNA without destroying it. Furthermore, saturation mutagenesis around the T7 promoter and systematic analyses of environmental conditions reveal design criteria that can be used to optimize information access. This simple but powerful ss-dsDNA architecture lays the foundation for information storage with versatile capabilities. DA - 2020/6/12/ PY - 2020/6/12/ DO - 10.1038/s41467-020-16797-2 VL - 11 IS - 1 SP - SN - 2041-1723 UR - https://doi.org/10.1038/s41467-020-16797-2 ER - TY - JOUR TI - Microgrid Protection and Control Schemes for Seamless Transition to Island and Grid Synchronization AU - Vukojevic, Aleksandar AU - Lukic, Srdjan T2 - IEEE TRANSACTIONS ON SMART GRID AB - Microgrid transitions to islanded mode and grid synchronization can be designed either as seamless transitions or as a black-start. Secure and reliable seamless transition represents one of the most challenging engineering tasks during the microgrid design phase. Existing literature has several shortcomings - proposed microgrids are either ungrounded or not effectively grounded; DER transformer configurations are not properly implemented; communications within the microgrid do not reflect realistic time delays and there is very little discussion of the impact of relay protection settings on the proposed microgrid protection. This paper presents a new microgrid protection and control scheme that enables seamless islanding and grid synchronization using the point of common coupling (PCC) breaker relays, battery energy storage system (BESS) inverter controller and remote input/output mirror bits based communications approach (85RIO). All schemes have been implemented in the field within the electric utility's microgrid installed on the 12.47kV distribution feeder. The results presented in this paper are based on approximately 9,000 islanding and grid synchronization transitions. DA - 2020/7// PY - 2020/7// DO - 10.1109/TSG.2020.2975850 VL - 11 IS - 4 SP - 2845-2855 SN - 1949-3061 KW - Microgrids KW - Islanding KW - Synchronization KW - Inverters KW - Relays KW - Voltage control KW - Grounding KW - Microgrid KW - microgrid protection and control KW - microgrid islanding detection KW - seamless islanding KW - seamless grid synchronization ER - TY - JOUR TI - Magnon-bipolar carrier drag thermopower in antiferromagnetic/ferromagnetic semiconductors: Theoretical formulation and experimental evidence AU - Polash, Md Mobarak Hossain AU - Vashaee, Daryoosh T2 - Physical Review B AB - Quantized spin-wave known as magnon, a bosonic quasiparticle, can drag electrons or holes via s-d exchange interaction and boost the thermopower over the conventional diffusive thermopower. P-type magnon-drag thermopower has been observed in both ferromagnetic and antiferromagnetic metallic and degenerate semiconductors. However, it has been less reported for intrinsic or $n$-type magnetic semiconductors; therefore, the impact of magnon-bipolar carrier drag on thermopower has remained unexplored. Here, a theoretical model for magnon-bipolar carrier drag thermopower is derived based on the magnon-carrier interaction lifetimes. The model predicts that the bipolar carrier drag thermopower becomes independent of both the carrier and magnon relaxation times. A proof of concept experiment is presented that confirms this prediction. We also report the observation of magnon-carrier drag thermopower in n-type and intrinsic ferromagnetic semiconductors experimentally. The p-type antiferromagnetic MnTe is doped with different amounts of Cr to produce nondegenerate and n-type semiconductors of various carrier concentrations. Cr dopants have a donor nature and create ferromagnetic-antiferromagnetic clusters due to the $\mathrm{C}{\mathrm{r}}^{3+}$ oxidation state. Heat capacity measurements confirm the presence of magnons in Cr-doped MnTe. It is shown that the magnon-drag thermopower is significantly reduced for 3%--5% Cr-doped samples due to bipolar drag effects and becomes negative for 14% and 20% Cr-doped MnTe due to dominant magnon-electron drag thermopower. DA - 2020/7/10/ PY - 2020/7/10/ DO - 10.1103/PhysRevB.102.045202 UR - https://doi.org/10.1103/PhysRevB.102.045202 ER - TY - JOUR TI - Self-Evolution Cascade Deep Learning Model for High-Speed Receiver Adaptation AU - Li, Bowen AU - Jiao, Brandon AU - Chou, Chih-Hsun AU - Mayder, Romi AU - Franzon, Paul T2 - IEEE TRANSACTIONS ON COMPONENTS PACKAGING AND MANUFACTURING TECHNOLOGY AB - The IBIS algorithmic modeling interface (IBIS-AMI) has become the standard methodology to model Serializer/Deserializer (SerDes) behavior for end-to-end high-speed serial link simulations. Meanwhile, machine learning (ML) techniques can mimic a black-box system behavior. This article proposes the self-evolution cascade deep learning (SCDL) model to show a parallel approach to effectively modeling adaptive SerDes behavior. Specifically, the proposed self-guide learning methodology uses its own failure experiences to optimize its future solution search according to the prediction of the receiver equalization adaptation trend. The proposed SCDL model can provide the high-correlation adaptation results, while the adaptation simulation time is much faster than conventional IBIS-AMI models. DA - 2020/6// PY - 2020/6// DO - 10.1109/TCPMT.2020.2992186 VL - 10 IS - 6 SP - 1043-1053 SN - 2156-3985 KW - Adaptation models KW - Integrated circuit modeling KW - Logic gates KW - Receivers KW - Deep learning KW - Data models KW - Training KW - Adaptation KW - behavior KW - cascade KW - deep learning KW - high correlation KW - IBIS algorithmic modeling interface (IBIS-AMI) KW - modeling KW - receiver KW - self-evolution cascade deep learning (SCDL) ER - TY - JOUR TI - Dual-beam potassium Voigt filter for atomic line imaging AU - Kudenov, Michael W. AU - Pantalone, Brett AU - Yang, Ruonan T2 - APPLIED OPTICS AB - Spectrally narrowband imaging in remote sensing applications can be advantageous for detecting atomic emission features. This is especially useful in detecting specific constituents within rocket plumes, which are challenging to discern from naturally occurring sunglints. In this paper, we demonstrate a dual-beam technique, implemented with a Wollaston prism, for calibrating a Voigt magneto-optical filter for a linear polarizer’s finite extinction ratio, as well as optical misalignment between the linear polarizers’ transmission axes. Such a strategy would be key towards expanding the filter’s field of view while maintaining its classification capabilities. Validation of the potassium Voigt filter is demonstrated using the simulation tool ElecSus in combination with a potassium hollow cathode lamp. RMS error between the filter’s temperature response and that of the simulation was approximately 2%. We then demonstrate the detection of a potassium model rocket motor outdoors alongside a sunglint. Results indicate a 20-fold increase in contrast when using our dual-beam calibration strategy. DA - 2020/6/10/ PY - 2020/6/10/ DO - 10.1364/AO.393649 VL - 59 IS - 17 SP - 5282-5289 SN - 2155-3165 ER - TY - JOUR TI - Editors' Choice-Critical Review-A Critical Review of Solid State Gas Sensors AU - Hunter, Gary W. AU - Akbar, Sheikh AU - Bhansali, Shekhar AU - Daniele, Michael AU - Erb, Patrick D. AU - Johnson, Kevin AU - Liu, Chung-Chiun AU - Miller, Derek AU - Oralkan, Omer AU - Hesketh, Peter J. AU - Manickam, Pandiaraj AU - Vander Wal, Randy L. T2 - JOURNAL OF THE ELECTROCHEMICAL SOCIETY AB - Solid state gas sensors are a core enabling technology to a range of measurement applications including industrial, safety, and environmental monitoring. The technology associated with solid-state gas sensors has evolved in recent years with advances in materials, and improvements in processing and miniaturization. In this review, we examine the state-of-the-art of solid state gas sensors with the goal of understanding the core technology and approaches, various sensor design methods to provide targeted functionality, and future prospects in the field. The structure, detection mechanism, and sensing properties of several types of solid state gas sensors will be discussed. In particular, electrochemical cells (solid and liquid), impedance/resistance based sensors (metal oxide, polymer, and carbon based structures), and mechanical sensing structures (resonators, cantilevers, and acoustic wave devices) as well as sensor arrays and supporting technologies, are described. Development areas for this field includes increased control of material properties for improved sensor response and durability, increased integration and miniaturization, and new material systems, including nano-materials and nano-structures, to address shortcomings of existing solid state gas sensors. DA - 2020/2/21/ PY - 2020/2/21/ DO - 10.1149/1945-7111/ab729c VL - 167 IS - 3 SP - SN - 1945-7111 ER - TY - JOUR TI - Communication Support for Unmanned Air Transportation AU - Namuduri, Kamesh AU - Fiebig, Uwe-Carsten AU - Hari, K. V. S. AU - Matolak, David W. AU - Guvenc, Ismail AU - Maattanen, Helka-Liina T2 - IEEE VEHICULAR TECHNOLOGY MAGAZINE AB - The four articles in this special section highlight some of the most important challenges in providing communication support for unmanned air transportation and solutions to address them. DA - 2020/6// PY - 2020/6// DO - 10.1109/MVT.2020.2985879 VL - 15 IS - 2 SP - 20-21 SN - 1556-6080 ER - TY - JOUR TI - A Software-Defined Radio Receiver for Wireless Recording From Freely Behaving Animals (vol 13, pg 979, 2019) AU - Jia, Yaoyao AU - Lee, Byunghun AU - Kong, Fanpeng AU - Zeng, Zhaoping AU - Connolly, Mark AU - Mahmoudi, Babak AU - Ghovanloo, Maysam T2 - IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS AB - Presents corrections to author affiliation information in the above named paper. DA - 2020/6// PY - 2020/6// DO - 10.1109/TBCAS.2020.2991644 VL - 14 IS - 3 SP - 631-631 SN - 1940-9990 KW - Receivers KW - Wireless communication KW - Animals KW - Biomedical engineering KW - Biomedical informatics ER - TY - JOUR TI - Evaluation of mechanical and biocompatibility properties of hydroxyapatite/manganese dioxide nanocomposite scaffolds for bone tissue engineering application AU - Azizi, Fatemeh AU - Heidari, Fatemeh AU - Fahimipour, Farahnaz AU - Sajjadnejad, Mohammad AU - Vashaee, Daryoosh AU - Tayebi, Lobat T2 - INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY AB - Abstract The aim of this research was to evaluate the mechanical properties, biocompatibility, and degradation behavior of scaffolds made of pure hydroxyapatite (HA) and HA‐modified by MnO 2 for bone tissue engineering applications. HA and MnO 2 were developed using sol‐gel and precipitation methods, respectively. The scaffolds properties were characterized using X‐ray diffraction (XRD), Fourier transform spectroscopy (FTIR), scanning electron microcopy (SEM), energy dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). The interaction of scaffold with cells was assessed using in vitro cell proliferation and alkaline phosphatase (ALP) assays. The obtained results indicate that the HA/MnO 2 scaffolds possess higher compressive strength, toughness, hardness, and density when compared to the pure HA scaffolds. After immersing the scaffold in the SBF solution, more deposited apatite appeared on the HA/MnO 2 , which results in the rougher surface on this scaffold compared to the pure HA scaffold. Finally, the in vitro biological analysis using human osteoblast cells reveals that scaffolds are biocompatible with adequate ALP activity. DA - 2020/9// PY - 2020/9// DO - 10.1111/ijac.13549 VL - 17 IS - 5 SP - 2439-2449 SN - 1744-7402 KW - biocompatibility KW - cold isostatic pressing KW - mechanical properties KW - nanocomposite ER - TY - JOUR TI - An Implantable Wireless Inductive Sensor System Designed to Monitor Prosthesis Motion in Total Joint Replacement Surgery AU - Mohammadbagherpoor, Hamed AU - Ierymenko, Paul AU - Craver, Meghan H. AU - Carlson, Jim AU - Dausch, David AU - Grant, Edward AU - Lucey, John D. T2 - IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING AB - Currently, the most common method for detecting prosthetic implant loosening is imaging. Unfortunately, imaging methods are imprecise in detecting the early signs of implant loosening. This paper describes a new wireless inductive proximity sensor system for detecting early implant loosening. The loosening of the implant is accurately detected by analyzing the electromagnetic field generated by the passive sensors located around the implant. The sensor system was modeled and simulated using COMSOL, and then tested experimentally. The inductive proximity sensor and the metallic implant form a coupled circuit is tuned to oscillate at a designed frequency. The circuit's integrated controller measures and records specific sensor's parameters such as resistance and inductance of the sensor that are directly related to the distance between the sensor system and the implant. A prototype has been developed and the results show that the designed proximity sensor is capable of measuring the loosening of the hip implant at 50 μm resolution at distances of less than 8 mm, and of 100 μm resolution at a distance of 15 mm. Furthermore, there is a good correlation between the simulated and experimental results. DA - 2020/6// PY - 2020/6// DO - 10.1109/TBME.2019.2943808 VL - 67 IS - 6 SP - 1718-1726 SN - 1558-2531 KW - Implants KW - Surgery KW - Immune system KW - Hip KW - Sensor systems KW - Prosthetics KW - Mathematical model KW - Electromagnetic field KW - passive LC sensor KW - prosthesis loosening detection KW - telemetry KW - wireless medical device ER - TY - JOUR TI - Drought Stress Detection Using Low-Cost Computer Vision Systems and Machine Learning Techniques AU - Ramos-Giraldo, Paula AU - Reberg-Horton, Chris AU - Locke, Anna M. AU - Mirsky, Steven AU - Lobaton, Edgar T2 - IT PROFESSIONAL AB - The real-time detection of drought stress has major implications for preventing cash crop yield loss due to variable weather conditions and ongoing climate change. The most widely used indicator of drought sensitivity/tolerance in corn and soybean is the presence or absence of leaf wilting during periods of water stress. We develop a low-cost automated drought detection system using computer vision coupled with machine learning (ML) algorithms that document the drought response in corn and soybeans field crops. Using ML, we predict the drought status of crop plants with more than 80% accuracy relative to expert-derived visual drought ratings. DA - 2020/// PY - 2020/// DO - 10.1109/MITP.2020.2986103 VL - 22 IS - 3 SP - 27-29 SN - 1941-045X UR - http://dx.doi.org/10.1109/mitp.2020.2986103 KW - Agriculture KW - Stress KW - Machine learning KW - Computer vision KW - Loss measurement KW - Stress measurement KW - Cameras ER - TY - JOUR TI - Gas-Permeable, Ultrathin, Stretchable Epidermal Electronics with Porous Electrodes AU - Zhou, Weixin AU - Yao, Shanshan AU - Wang, Hongyu AU - Du, QIngchuan AU - Ma, Yanwen AU - Zhu, Yong T2 - ACS NANO AB - We present gas-permeable, ultrathin, and stretchable electrodes enabled by self-assembled porous substrates and conductive nanostructures. An efficient and scalable breath figure method is employed to introduce the porous skeleton, and then silver nanowires (AgNWs) are dip-coated and heat-pressed to offer electric conductivity. The resulting film has a transmittance of 61%, sheet resistance of 7.3 Ω/sq, and water vapor permeability of 23 mg cm–2 h–1. With AgNWs embedded below the surface of the polymer, the electrode exhibits excellent stability in the presence of sweat and after long-term wear. We demonstrate the promising potential of the electrode for wearable electronics in two representative applications: skin-mountable biopotential sensing for healthcare and textile-integrated touch sensing for human–machine interfaces. The electrode can form conformal contact with human skin, leading to low skin–electrode impedance and high-quality biopotential signals. In addition, the textile electrode can be used in a self-capacitance wireless touch sensing system. DA - 2020/5/26/ PY - 2020/5/26/ DO - 10.1021/acsnano.0c00906 VL - 14 IS - 5 SP - 5798-5805 SN - 1936-086X KW - gas permeable KW - breath figure KW - silver nanowires KW - healthcare KW - human-machine interfaces ER - TY - JOUR TI - 2.3 kV 4H-SiC Accumulation-Channel Split-Gate Planar Power MOSFETs With Reduced Gate Charge AU - Agarwal, Aditi AU - Han, Kijeong AU - Baliga, B. Jayant T2 - IEEE JOURNAL OF THE ELECTRON DEVICES SOCIETY AB - 2.3 kV 4H-SiC split-gate (SG) planar accumulation-channel power MOSFETs have been successfully manufactured in a 6 inch commercial foundry with good parametric distributions. The measured electrical characteristics of these devices are compared with conventional ACCUFETs manufactured with the same cell-pitch and process to quantify the improved performance. The gate charge and high-frequency figures-of-merit (HF-FOM) of the 2.3 kV SG-MOSFETs were experimentally verified to be a factor of 1.8x better than that of the conventional MOSFETs with no difference in specific on-resistance. DA - 2020/// PY - 2020/// DO - 10.1109/JEDS.2020.2991355 VL - 8 IS - 1 SP - 499-504 SN - 2168-6734 KW - 4H-SiC KW - 2.3 kV devices KW - accumulation channel KW - C-gd KW - planar-gate MOSFET KW - Q(gd) KW - R-on,R-sp KW - silicon carbide KW - split-gate ER - TY - JOUR TI - Off-Grid Aware Channel and Covariance Estimation in mmWave Networks AU - Anjinappa, Chethan Kumar AU - Gurbuz, Ali Cafer AU - Yapici, Yavuz AU - Guvenc, Ismail T2 - IEEE Transactions on Communications AB - The spectrum scarcity at sub-6 GHz spectrum has made millimeter-wave (mmWave) frequency band a key component of the next-generation wireless networks. While mmWave spectrum offers extremely large transmission bandwidths to accommodate ever-increasing data rates, unique characteristics of this new spectrum need special consideration to achieve the promised network throughput. In this work, we consider the off-grid targets (basis mismatch) problem for mmWave communications. The off-grid effect naturally appears in compressed sensing (CS) techniques adopting a discretization approach for representing the angular domain. This approach yields a finite set of discrete angle points, which are an approximation to the continuous angular space, and hence degrade the accuracy of related parameter estimation. In order to cope with the off-grid effect, we present a novel parameter-perturbation framework to efficiently estimate the channel and the covariance for mmWave networks. The proposed algorithms employ a smart perturbation mechanism in conjunction with a low-complexity greedy framework of simultaneous orthogonal matching pursuit (SOMP), and jointly solve for the off-grid parameters and weights. Numerical results show a significant performance improvement through our novel framework as a result of handling the off-grid effects, which is totally ignored in the conventional sparse mmWave channel or covariance estimation algorithms. DA - 2020/6// PY - 2020/6// DO - 10.1109/TCOMM.2020.2980829 VL - 68 IS - 6 SP - 3908-3921 UR - https://doi.org/10.1109/TCOMM.2020.2980829 KW - Channel estimation KW - Estimation KW - Covariance matrices KW - MIMO communication KW - Matching pursuit algorithms KW - Radio frequency KW - Compressed sensing KW - 5G KW - basis mismatch KW - channel estimation KW - compressed sensing KW - covariance estimation KW - MIMO KW - off-grid KW - parameter perturbed KW - sparse channel estimation ER - TY - JOUR TI - Electronic transport in epitaxial 4H-SiC based Schottky diodes modified selectively by swift heavy ions AU - Kumar, Vibhor AU - Maan, A. S. AU - Akhtar, Jamil T2 - MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING AB - Modifications in the defects and electronic transport properties of epitaxial 4H-nSiC(0001) Schottky barrier diodes have been carried out by selective 200 MeV Ag+14 ions irradiation, i.e., ions projected only on the Schottky contact area of the diode using a mask. Forward bias current-voltage (I–V) characteristics are measured in temperature (T) range from 273 K to 473 K. Interestingly, the barrier height found increased from 1.20 eV to 1.35 eV at 273 K and from 1.24 eV to 1.42 eV at 348 K after selective ion irradiation. At T ≥ 373 K, double barrier height features have seen in the I–V-T plots. The reverse bias I–V characteristics are measured up to −200 V, and in T range from 298 K to 473 K. The leakage current density found decreased from 9.57 × 10-9 A/cm2 to 2.98 × 10-10 A/cm2 at 298 K and from 5.53 × 10-8 A/cm2 to 4.17 × 10-8 A/cm2 at 373 K after selective irradiation, and deteriorated after that. The defects in pristine SiC with activation energy (ΔEA) of 0.29 eV and 0.13 eV are removed and a single defect with ΔEA of 0.38 eV observed after selective ion irradiation. Moreover, asymmetries are observed in capacitance-voltage characteristics of selectively irradiated devices. Role of electronic and nuclear energy loss mechanisms have been discussed to rationalize the performance of diodes. The proposed technique may be applicable in addressing the issues related to interface and bulk level defects in advance semiconducting materials, without using high temperatures. DA - 2020/8/15/ PY - 2020/8/15/ DO - 10.1016/j.mssp.2020.105108 VL - 115 SP - SN - 1873-4081 KW - SiC KW - Schottky barrier diode KW - Swift heavy ion irradiation KW - Double barrier height KW - Defects ER - TY - JOUR TI - Dynamic Microgrids With Self-Organized Grid-Forming Inverters in Unbalanced Distribution Feeders AU - Du, Yuhua AU - Lu, Xiaonan AU - Tu, Hao AU - Wang, Jianhui AU - Lukic, Srdjan T2 - IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS AB - In contrast to conventional static microgrids (MGs), MGs with dynamic and adjustable territories (i.e., dynamic MGs) are proposed and implemented in this article. Dynamic MGs are commonly dominated by grid-forming inverters and nested in unbalanced distribution feeders. Unlike balanced systems where only positive-sequence components exist, proper operation of unbalanced dynamic MGs presents additional challenges. A distributed secondary control strategy is developed in this article for distributed generators (DGs) interfaced with grid-forming inverters in unbalanced dynamic MGs by providing coordinated regulations on both positive- and negative-sequence system models. System frequency and voltage are under constant regulation, along with voltage unbalance (VU) management for multiple critical load buses (CLBs). The proposed control strategy enables seamless system transition during unbalanced dynamic MGs reconfiguration and guarantees proportional positive- and negative-sequence power-sharing among connected DGs with respect to system topology variation. Detailed controller designs are provided and stability analyses are derived. The proposed control strategy is fully implemented in hardware controllers and validated on a hardware-in-the-loop (HIL) MG testbed. DA - 2020/6// PY - 2020/6// DO - 10.1109/JESTPE.2019.2936741 VL - 8 IS - 2 SP - 1097-1107 SN - 2168-6785 KW - Inverters KW - Topology KW - Voltage control KW - Microgrids KW - Control systems KW - Transient analysis KW - Network topology KW - Distributed control KW - dynamic microgrids (MGs) KW - network reconfiguration KW - secondary control KW - unbalanced system ER - TY - JOUR TI - Modified gaphene oxide (GO) particles in peptide hydrogels: a hybrid system enabling scheduled delivery of synergistic combinations of chemotherapeutics AU - Schneible, John D. AU - Shi, Kaihang AU - Young, Ashlyn T. AU - Ramesh, Srivatsan AU - He, Nanfei AU - Dowdey, Clay E. AU - Dubnansky, Jean Marie AU - Libya, Radina L. AU - Gao, Wei AU - Santiso, Erik AU - Daniele, Michael AU - Menegatti, Stefano T2 - JOURNAL OF MATERIALS CHEMISTRY B AB - The scheduled delivery of synergistic drug combinations is increasingly recognized as highly effective against advanced solid tumors. Of particular interest are composite systems that release a sequence of drugs with defined kinetics and molar ratios to enhance therapeutic effect, while minimizing the dose to patients. In this work, we developed a homogeneous composite comprising modified graphene oxide (GO) nanoparticles embedded in a Max8 peptide hydrogel, which provides controlled kinetics and molar ratios of release of doxorubicin (DOX) and gemcitabine (GEM). First, modified GO nanoparticles (tGO) were designed to afford high DOX loading and sustained release (18.9% over 72 h and 31.4% over 4 weeks). Molecular dynamics simulations were utilized to model the mechanism of DOX loading as a function of surface modification. In parallel, a Max8 hydrogel was developed to release GEM with faster kinetics and achieve a 10-fold molar ratio to DOX. The selected DOX/tGO nanoparticles were suspended in a GEM/Max8 hydrogel matrix, and the resulting composite was tested against a triple negative breast cancer cell line, MDA-MB-231. Notably, the composite formulation afforded a combination index of 0.093 ± 0.001, indicating a much stronger synergism compared to the DOX-GEM combination co-administered in solution (CI = 0.396 ± 0.034). DA - 2020/5/7/ PY - 2020/5/7/ DO - 10.1039/d0tb00064g VL - 8 IS - 17 SP - 3852-3868 SN - 2050-7518 ER - TY - JOUR TI - Investigation of biasing conditions and energy dissipation in electrochemically controlled capillarity liquid metal electronics AU - Wang, Meng AU - Lei, Wen Tai AU - Dong, Jian AU - Dickey, Michael D. AU - Adams, Jacob J. T2 - ELECTRONICS LETTERS AB - This Letter investigates the trade-off between the biasing conditions (biasing current and electrolyte concentration) and energy dissipation in high-frequency liquid metal electronics using electrochemically controlled capillarity (ECC). ECC can control the interfacial tension of liquid metal via DC current as a method to move the metal in capillaries. It requires a conductive electrolyte to facilitate the electrochemical reactions. Here, the authors measure the withdrawal rate of liquid metal under different biasing currents and electrolyte concentrations. The results indicate that a larger biasing current and a more concentrated electrolyte induce a faster withdrawal motion of liquid metal. This Letter also explores the change of antenna efficiency when different electrolyte concentrations are chosen. The selection of electrolyte concentration for high-antenna efficiency conflicts with the need for fast withdrawal speed and low-DC power consumption of the liquid metal system, therefore requiring a balance among the various parameters when ECC is applied in practical liquid metal electronics. DA - 2020/3/30/ PY - 2020/3/30/ DO - 10.1049/el.2019.3925 VL - 56 IS - 7 SP - 323-324 SN - 1350-911X ER - TY - JOUR TI - A Pipeline for Adaptive Filtering and Transformation of Noisy Left-Arm ECG to Its Surrogate Chest Signal AU - Mohaddes, Farzad AU - Silva, Rafael AU - Akbulut, Fatma AU - Zhou, Yilu AU - Tanneeru, Akhilesh AU - Lobaton, Edgar AU - Lee, Bongmook AU - Misra, Veena T2 - Electronics AB - The performance of a low-power single-lead armband in generating electrocardiogram (ECG) signals from the chest and left arm was validated against a BIOPAC MP160 benchtop system in real-time. The filtering performance of three adaptive filtering algorithms, namely least mean squares (LMS), recursive least squares (RLS), and extended kernel RLS (EKRLS) in removing white (W), power line interference (PLI), electrode movement (EM), muscle artifact (MA), and baseline wandering (BLW) noises from the chest and left-arm ECG was evaluated with respect to the mean squared error (MSE). Filter parameters of the used algorithms were adjusted to ensure optimal filtering performance. LMS was found to be the most effective adaptive filtering algorithm in removing all noises with minimum MSE. However, for removing PLI with a maximal signal-to-noise ratio (SNR), RLS showed lower MSE values than LMS when the step size was set to 1 × 10−5. We proposed a transformation framework to convert the denoised left-arm and chest ECG signals to their low-MSE and high-SNR surrogate chest signals. With wide applications in wearable technologies, the proposed pipeline was found to be capable of establishing a baseline for comparing left-arm signals with original chest signals, getting one step closer to making use of the left-arm ECG in clinical cardiac evaluations. DA - 2020/5/23/ PY - 2020/5/23/ DO - 10.3390/electronics9050866 VL - 9 IS - 5 SP - 866 UR - https://doi.org/10.3390/electronics9050866 KW - adaptive filtering KW - wearable ECE armband KW - filter optimization KW - left-arm ECG KW - single-lead ECG KW - ECG transformation ER - TY - JOUR TI - Dielectric and conducting properties of unintentionally and Sn-doped beta-Ga2O3 studied by terahertz spectroscopy AU - Blumenschein, Nick AU - Kadlec, Christelle AU - Romanyuk, Oleksandr AU - Paskova, Tania AU - Muth, John F. AU - Kadlec, Filip T2 - JOURNAL OF APPLIED PHYSICS AB - Dielectric and conducting properties of unintentionally doped bulk and Sn-doped thin film β-Ga2O3 samples were studied using time-domain terahertz spectroscopy. Complex permittivity and optical conductivity spectra from 0.25 to 2.5 THz were obtained experimentally over a broad temperature range. The low-temperature spectra of the unintentionally doped sample were fit using a model involving two oscillators. The parameters of one of them show an unusual temperature dependence, in particular, a pronounced increase in the oscillator strength upon heating above 50 K. This is interpreted as an absorption due to thermally activated charge carriers moving in localized potential minima linked to the unintentional doping. Upon heating, the influence of this optical conductivity mechanism strongly increases, and the sample becomes opaque in the THz range near 100 K. The nanocrystalline Sn-doped Ga2O3 thin film sample exhibits a much higher optical conductivity than the unintentionally doped bulk sample, and its spectra are remarkably stable over a broad temperature range (4–750 K). This first study of β-Ga2O3 based on phase-sensitive THz spectroscopy reveals how the impurities influence the high-frequency conductive properties of the material. DA - 2020/4/30/ PY - 2020/4/30/ DO - 10.1063/1.5143735 VL - 127 IS - 16 SP - SN - 1089-7550 ER - TY - JOUR TI - Multilinear Singular Value Decomposition for Millimeter Wave Channel Parameter Estimation AU - Ruble, Macey AU - Guvenc, Ismail T2 - IEEE ACCESS AB - Fifth generation (5G) cellular standards are set to utilize millimeter wave (mmWave) frequencies, which enable data speeds greater than 10 Gbps and sub-centimeter localization accuracy. These capabilities rely on accurate estimates of the channel parameters, which we define as the angle of arrival, angle of departure, and path distance for each path between the transmitter and receiver. Estimating the channel parameters in a computationally efficient manner poses a challenge because it requires estimation of parameters from a high-dimensional measurement - particularly for multi-carrier systems since each subcarrier must be estimated separately. Additionally, channel parameter estimation must be able to handle hybrid beamforming, which uses a combination of digital and analog beamforming to reduce the number of required analog to digital converters. This paper introduces a channel parameter estimation technique based on the multilinear singular value decomposition (MSVD), a Tucker form tensor analog of the singular value decomposition, for massive multiple input multiple output (MIMO) multi-carrier systems with hybrid beamforming. The MSVD tensor estimation approach is more computationally efficient than methods such as the canonical polyadic decomposition (CPD) and the Tucker form of the MSVD enables paths to be extracted based on signal energy. The algorithms performance is compared to the CPD method and shown to closely match the Cramer-Rao bound (CRB) of channel parameter estimates through simulations. Additionally, limitations of channel parameter estimation and communication waveform effects are studied. DA - 2020/// PY - 2020/// DO - 10.1109/ACCESS.2020.2988485 VL - 8 SP - 75592-75606 SN - 2169-3536 KW - Channel estimation KW - Tensile stress KW - OFDM KW - Parameter estimation KW - MIMO communication KW - Receivers KW - Singular value decomposition KW - AOA KW - AOD KW - channel estimation KW - MSVD KW - massive MIMO KW - mmWave KW - OFDM KW - SVD KW - tensor estimation ER - TY - JOUR TI - Manufacturing and characterization of mechanical, biological and dielectric properties of hydroxyapatite-barium titanate nanocomposite scaffolds AU - Tavangar, Mina AU - Heidari, Fatemeh AU - Hayati, Raziye AU - Tabatabaei, Fahimeh AU - Vashaee, Daryoosh AU - Tayebi, Lobat T2 - CERAMICS INTERNATIONAL AB - In this research, hydroxyapatite (HA)-based ceramics were produced as suitable ceramic implants for orthopedic applications. To improve the physical, mechanical, electrical and biological properties of pure HA, we developed composite scaffolds of HA-barium titanate (BT) by cold isostatic pressing and sintering. Microstructure, crystal phases, and molecular structure were analyzed by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR), respectively. Bulk density values were measured using the Archimedes method. The effect of different percentages of BT on cell proliferation, viability, and ALP activity of dental pulp stem cells (DPSCs) was assessed by ProstoBlue assay, Live/Dead staining, and p-NPP assay. The obtained results indicate that the HA-BT scaffolds possess higher compressive strength, toughness, density, and hardness compared with pure HA scaffolds. After immersing the scaffold in SBF solution, more deposited apatite appeared on the HA-BT, which results in rougher surface on this scaffold thanpure HA. Electrical properties of HA in the presence of BT are improved. Based on the results of cell culture experiments, composites containing 40, 50 and 60 %wt of BT have excellent biocompatibility, with the best results occurring for the sample with 50 %wt BT. DA - 2020/5// PY - 2020/5// DO - 10.1016/j.ceramint.2019.12.157 VL - 46 IS - 7 SP - 9086-9095 SN - 1873-3956 KW - Nanocomposite KW - Barium titanate KW - Mechanical property KW - Piezoelectric property KW - Biocompatibility ER - TY - JOUR TI - Modeling and Analysis of Conflicting Information Propagation in a Finite Time Horizon AU - Wang, Jie AU - Wang, Wenye AU - Wang, Cliff T2 - IEEE/ACM Transactions on Networking AB - Emerging mobile applications enable people to connect with one another more easily than ever, which causes networked systems, e.g., online social networks (OSN) and Internet-of-Things (IoT), to grow rapidly in size, and become more complex in structure. In these systems, different, even conflicting information, e.g., rumor v.s. truth, and malware v.s. security patches, can compete with each other during their propagation over individual connections. For such information pairs, in which a desired information kills its undesired counterpart on contact, an interesting yet challenging question is when and how fast the undesired information dies out. To answer this question, we propose a Susceptible-Infectious-Cured (SIC) propagation model, which captures short-term competitions between the two pieces of information, and define extinction time and half-life time, as two pivots in time, to quantify the dying speed of the undesired information. Our analysis revealed the impact of network topology and initial conditions on the lifetime of the undesired information. In particular, we find that, the Cheeger constant that measures the edge expansion property of a network steers the scaling law of the lifetime with respect to the network size, and the vertex eccentricities that are easier to compute provide accurate estimation of the lifetime. Our analysis also sheds light on where to inject the desired information, such that its undesired counterpart can be eliminated faster. DA - 2020/6// PY - 2020/6// DO - 10.1109/TNET.2020.2976972 VL - 28 IS - 3 SP - 972-985 UR - https://doi.org/10.1109/TNET.2020.2976972 KW - Epidemics KW - Computer viruses KW - Analytical models KW - Network topology KW - Topology KW - Silicon carbide KW - Information propagation KW - conflicting information KW - epidemic models KW - network dynamics ER - TY - JOUR TI - Exploring the relationship between geomagnetic activity and human heart rate variability AU - Mattoni, Matthew AU - Ahn, Sangtae AU - Frohlich, Carla AU - Frohlich, Flavio T2 - EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY AB - Both geomagnetic and solar activity fluctuate over time and have been proposed to affect human physiology. Heart rate variability (HRV) has substantial health implications regarding the ability to adapt to stressors and has been shown to be altered in many cardiovascular and neurological disorders. Intriguingly, previous work found significant, strong correlations between HRV and geomagnetic/solar activity. The purpose of this study to replicate these findings. We simultaneously measured HRV during a 30-day period. We recruited 20 healthy participants and measured their HRV for a 30-day period. We also collected geomagnetic and solar activity during this period for investigating their relationship with the HRV data. In agreement with previous work, we found several significant correlations between short-term HRV and geophysical time-series. However, after correction for autocorrelation, which is inherent in time-series, the only significant results were an increase in very low frequency during higher local geomagnetic activity and a geomagnetic anticipatory decrease in heart rate a day before the higher global geomagnetic activity. Both correlations were very low. The loss of most significant effects after this correction suggests that previous findings may be a result of autocorrelation. A further note of caution is required since our and the previous studies in the field do not correct for multiple comparisons given the exploratory analysis strategy. We thus conclude that the effects of geomagnetic and solar activity are (if present) most likely of very small effect size and we question the validity of the previous studies given the methodological concerns we have uncovered with our work. DA - 2020/6// PY - 2020/6// DO - 10.1007/s00421-020-04369-7 VL - 120 IS - 6 SP - 1371-1381 SN - 1439-6327 KW - Heart rate variability KW - Geomagnetic activity KW - Solar activity ER - TY - JOUR TI - Analysis of Network Effect in the Competition of Self- Publishing Market AU - Chen, Li AU - Tang, Wen T2 - JOURNAL OF THEORETICAL AND APPLIED ELECTRONIC COMMERCE RESEARCH AB - Self-publishing has become a popular e-commerce model. In the current study, we build a duopoly model to examine the impact of the network effect on competition in this emerging market. We investigate four cases depending on two factors: market size and the self-publishing platforms’ compatibility strategy. Our results show that self-publishing writers receive higher royalties compared with the scenario of no network effect except in the case of both platforms choosing incompatibility strategy in the standard market. We also find that self-publishing platforms do not always benefit from the network effect. In the standard market, the platforms will be better off only when they choose incompatibility strategy and the network effect intensity is greater than a certain threshold. In the expanded market, our computational analysis shows that the revenue of the less-known self-publishing platform increases, but the revenue of the leading platform decreases when both platforms choose compatibility strategy. Our findings also show that both self-publishing platforms prefer incompatibility strategy under a strong network effect in the standard market. Otherwise, they prefer compatibility strategy under a weak network effect. In the expanded market, self-publishing platforms have an incentive to choose incompatibility strategy. DA - 2020/9// PY - 2020/9// DO - 10.4067/S0718-18762020000300105 VL - 15 IS - 3 SP - 50-68 SN - 0718-1876 KW - Self-publishing KW - Online publishing KW - Network effect KW - Compatibility strategy KW - Duopoly competition ER - TY - JOUR TI - Post-Silicon Microarchitecture AU - Kumar, Chanchal AU - Chaudhary, Aayush AU - Bhawalkar, Shubham AU - Mathur, Utkarsh AU - Jain, Saransh AU - Vastrad, Adith AU - Rotenberg, Eric T2 - IEEE COMPUTER ARCHITECTURE LETTERS AB - Microprocessors are designed to provide good general performance across a range of benchmarks. As such, microarchitectural techniques which provide good speedup for only a small subset of applications are not attractive when designing a general-purpose core. We propose coupling a reconfigurable fabric with the CPU, on the same chip, via a simple and flexible interface to allow post-silicon development of application-specific microarchitectures. The interface supports observation and intervention at key pipeline stages of the CPU, so that exotic microarchitecture designs (with potentially narrow applicability) can be synthesized in the reconfigurable fabric and seem like components that were hardened into the core. DA - 2020/// PY - 2020/// DO - 10.1109/LCA.2020.2978841 VL - 19 IS - 1 SP - 26-29 SN - 1556-6064 KW - Microarchitecture KW - Payloads KW - Fabrics KW - Indexes KW - Prefetching KW - Registers KW - Synchronization KW - Adaptable architectures KW - microarchitecture KW - reconfigurable hardware ER - TY - CONF TI - Quantum Circuits for Dynamic Runtime Assertions in Quantum Computation AU - Liu, J. AU - Byrd, G. AU - Zhou, H. T2 - Twenty-Fifth International Conference on Architectural Support for Programming Languages and Operating Systems AB - In this paper, we propose quantum circuits for runtime assertions, which can be used for both software debugging and error detection. Runtime assertion is challenging in quantum computing for two key reasons. First, a quantum bit (qubit) cannot be copied, which is known as the non-cloning theorem. Second, when a qubit is measured, its superposition state collapses into a classical state, losing the inherent parallel information. In this paper, we overcome these challenges with runtime computation through ancilla qubits, which are used to indirectly collect the information of the qubits of interest. We design quantum circuits to assert classical states, entanglement, and superposition states. Our experimental results show that they are effective in debugging as well as improving the success rate for various quantum algorithms on IBM Q quantum computers. C2 - 2020/// C3 - ASPLOS '20: Proceedings of the Twenty-Fifth International Conference on Architectural Support for Programming Languages and Operating Systems DA - 2020/// PY - 2020/3// DO - 10.1145/3373376.3378488 SP - 1017–1030 PB - Association for Computing Machinery UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85082381669&partnerID=MN8TOARS KW - Quantum Computing KW - Runtime Assertion ER - TY - JOUR TI - Fabrication of 2D Capacitive Micromachined Ultrasonic Transducer (CMUT) Arrays on Insulating Substrates With Through-Wafer Interconnects Using Sacrificial Release Process AU - Adelegan, Oluwafemi J. AU - Coutant, Zachary A. AU - Zhang, Xiao AU - Yamaner, Feysel Yalcin AU - Oralkan, Omer T2 - Journal of Microelectromechanical Systems AB - A critical component in a three-dimensional (3D) ultrasound imaging system is a two-dimensional (2D) transducer array. A 2D transducer array is also essential for the implementation of a compact form factor focused ultrasound system for therapeutic applications. Considering the difficulty associated with developing 2D transducer arrays using piezoelectric technology, capacitive micromachined ultrasonic transducer (CMUT) technology with the inherent advantages has emerged as a candidate to develop these devices. Previously, we demonstrated that 2D CMUT arrays can be fabricated with through-glass-via interconnects on borosilicate substrates using anodic bonding. In this paper, we present a fabrication process for implementing 16×16-element 2D CMUT arrays on an alkali-free glass substrate using the sacrificial release method. The vacuum-sealed 16 × 16element 2D CMUT array is built on an SGW3 glass substrate with copper through-glass interconnects. The fabrication process developed for the 2D CMUT array is described in detail. Across the 256 elements of the 2D CMUT array, the mean resonant frequency is measured as 4.76 MHz with a standard deviation of 46.6 kHz. Also, the mean device capacitance across the array is measured as 1.17 pF with a standard deviation of 0.12 pF, and these results agree with the finite-element analysis. This study shows an alternative method to fabricate 2D CMUT arrays on glass substrates with metal interconnects, especially when the substrate is not suitable for anodic bonding. In addition to improved reliability and reduction in parasitic interconnect capacitance and resistance, this fabrication method benefits from the flexibility of developing 2D CMUT arrays on any type of insulating substrate, and still attain optimum uniformity in both yield and functionality of the fabricated devices. DA - 2020/8// PY - 2020/8// DO - 10.1109/JMEMS.2020.2990069 VL - 29 IS - 4 SP - 553-561 UR - https://doi.org/10.1109/JMEMS.2020.2990069 KW - Capacitive micromachined ultrasonic transducer (CMUT) KW - 2D arrays KW - glass substrate KW - alkali-free glass KW - through-glass-Vias (TGV) KW - sacrificial release process ER - TY - JOUR TI - An Accurate Calorimetric Loss Measurement Method for SiC MOSFETs AU - Anurag, Anup AU - Acharya, Sayan AU - Bhattacharya, Subhashish T2 - IEEE Journal of Emerging and Selected Topics in Power Electronics AB - An accurate measurement of conduction and switching losses in the power semiconductor devices is necessary in order to design and evaluate the thermal management system of modern converter systems. Conventionally, electrical measurement methods, such as the double-pulse tests (DPTs), are used for measuring the switching losses. However, with the advent of wide-bandgap (WBG) devices that have fast switching transients, it is rather difficult to capture the waveforms accurately during switching transitions, and consequently, the measurement of switching loss becomes inaccurate. In addition, the measurement of switching waveforms depends on the voltage and current probes, as well as the oscilloscope used for the measurement, which makes this method prone to errors. This necessitates the use of measurement methods, which can provide much higher accuracy than the existing conventional electrical methods. Calorimetric methods are based on comparatively slow temperature measurements and do not rely on the measurements of fast switching transitions of voltages and currents, thus eliminating the demand for measuring fast switching transitions. This paper presents an accurate calorimetric method for measuring the device losses, which can be used to determine individual loss components accurately (conduction, turn-on, and turn-off losses). In addition to the turn-on and turn-off losses, this method can evaluate the charging and discharging losses of the device. The novelty of the method lies in the fact that a single setup can be used to measure all possible losses that can occur in a device during converter operation. The calorimetric test setup is described, and a novel modulation scheme is introduced, which enables the segregation of the individual losses. The experimental test setup is built and the method is verified by measuring the losses of a 900-V, 23-A Wolfspeed C3M0120090D SiC MOSFET. DA - 2020/6// PY - 2020/6// DO - 10.1109/JESTPE.2019.2920935 VL - 8 IS - 2 SP - 1644-1656 J2 - IEEE J. Emerg. Sel. Topics Power Electron. OP - SN - 2168-6777 2168-6785 UR - http://dx.doi.org/10.1109/jestpe.2019.2920935 DB - Crossref KW - Loss measurement KW - Semiconductor device measurement KW - Temperature measurement KW - Switching loss KW - Switches KW - Current measurement KW - MOSFET KW - Calorimetric methods KW - conduction losses KW - hard switching losses KW - semiconductor devices KW - SiC MOSFET KW - silicon carbide KW - switching loss measurement ER - TY - JOUR TI - 2020 RFIC Symposium AU - Khalil, Waleed AU - Floyd, Brian AU - Shana'a, Osama T2 - IEEE MICROWAVE MAGAZINE AB - Presents information on the RFIC 2020 Conference. DA - 2020/5// PY - 2020/5// DO - 10.1109/MMM.2020.2971371 VL - 21 IS - 5 SP - 30-32 SN - 1557-9581 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85083048661&partnerID=MN8TOARS ER - TY - JOUR TI - Experimental Realization of Heavily p-doped Half-Heusler CoVSn Compound AU - Zaferani, Sadeq Hooshmand AU - Darebaghi, Alireza AU - Hong, Soon-Jik AU - Vashaee, Daryoosh AU - Ghomashchi, Reza T2 - ENERGIES AB - Hypothetical half-Heusler (HH) ternary alloy of CoVSn has already been computationally investigated for possible spintronics and thermoelectric applications. We report the experimental realization of this compound and the characterizations of its thermoelectric properties. The material was synthesized by a solid-state reaction of the stoichiometric amounts of the elements via powder metallurgy (30 h mechanical milling and annealing at 900 °C for 20 h) and spark plasma sintering (SPS). The temperature-dependent ternary thermodynamic phase diagram of Co-V-Sn was further calculated. The phase diagram and detailed analysis of the synthesized material revealed the formation of the non-stoichiometry HH CoVSn, mixed with the binary intermetallic phases of SnV3, Co2Sn, and Co3V. The combination of X-ray diffraction, energy-dispersive X-ray spectroscopy, and thermoelectric transport properties confirmed the formation of a multi-phase compound. The analysis revealed the predicted thermoelectric features (zT = 0.53) of the highly doped CoVSn to be compromised by the formation of intermetallic phases (zT ≈ 0.007) during synthesis. The additional phases changed the properties from p- to overall n-type thermoelectric characteristics. DA - 2020/3// PY - 2020/3// DO - 10.3390/en13061459 VL - 13 IS - 6 SP - SN - 1996-1073 KW - half-Heusler KW - CoVSn KW - thermoelectric KW - heterogeneous structure ER - TY - JOUR TI - Asymmetric Transformer Design With Multiband Frequency Response for Simultaneous Power and Data Transfer AU - Zannat, Nazia AU - Franzon, Paul D. T2 - IEEE TRANSACTIONS ON COMPONENTS PACKAGING AND MANUFACTURING TECHNOLOGY AB - This article presents a novel approach to generate multiple passbands from an asymmetric two-coil transformer. The details of the asymmetry between the primary and secondary coils control the passbands' location and bandwidth (BW). A cylindrical asymmetric connector was designed and prototyped. The S-parameters were measured with a vector network analyzer (VNA), which shows a very good match with the theoretical model up to the second passband frequency (10 MHz-1 GHz). The first passband is used for power transfer since the lower frequency is better for power transmission. The higher frequency of the second passband can be used to transmit high BW data. A carrier signal centered at the second passband frequency was used to modulate digital data at the transmitter side and demodulated at the receiver side. This connector can be used for transmitting only power, or only data, or both power and data simultaneously. We demonstrate 19 mW of power transfer and 100 Mb/s of data transfer simultaneously in a 5-mm-diameter and 7-mm high cylindrically coupled structure. To the best of our knowledge, it is the highest data rate demonstrated through a wireless power transfer link. DA - 2020/4// PY - 2020/4// DO - 10.1109/TCPMT.2020.2977045 VL - 10 IS - 4 SP - 644-653 SN - 2156-3985 KW - Frequency response KW - Passband KW - Bandwidth KW - Mathematical model KW - Connectors KW - Inductors KW - Data transfer KW - Asymmetric transformer design KW - communication on wireless power transfer (WPT) link KW - inductive power transfer KW - inductively coupled channel ER - TY - JOUR TI - Stochastic multistage co-planning of integrated energy systems considering power-to-gas and the cap-and-trade market AU - Liang, Junkai AU - Tang, Wenyuan T2 - INTERNATIONAL JOURNAL OF ELECTRICAL POWER & ENERGY SYSTEMS AB - This paper develops an expansion co-planning model for integrated power and gas systems where uncertainties in both systems are considered. The power-to-gas technology is modeled and considered as a potential solution for some worldwide societal goals such as decarbonized economy and 100% renewable penetration. Compared with expansion planning models for power systems, the complexity of expansion co-planning models is severely exacerbated by random variables in gas systems. A scenario based decomposition scheme called branch-and-price is presented. The numerical results demonstrate the effectiveness of the proposed method and show the economic value of power-to-gas technology. DA - 2020/7// PY - 2020/7// DO - 10.1016/j.ijepes.2020.105817 VL - 119 SP - SN - 1879-3517 KW - Branch-and-price algorithm KW - Multistage stochastic programming KW - Expansion co-planning for integrated power and gas systems KW - Power-to-gas ER - TY - JOUR TI - The North Carolina State University Rabbit Radar: Build a Frequency-Modulated Continuous-Wave Radar in a Day [Application Notes] AU - Dwye, Matthew AU - Ricketts, David S. T2 - IEEE MICROWAVE MAGAZINE AB - i»?We present the design and hand fabrication of a frequency-modulated continuous-wave (FMCW) radar that teaches practicing engineers and students the fundamentals of radar theory, microwave systems, and component design. The fabrication can be done by hand-cutting simple shapes of foil with a knife or by cutting more complex shapes of foil with a 2D cutter from a hobby store [1]. We provide a brief overview of the theory of operation for the FMCW system and each component used. We then describe the design procedure for each component along with experimental results from the fabricated components. The frequency of operation was chosen to be 925 MHz, or around 1 GHz. This decision was made for multiple reasons. First, the frequency is within an Industry, Science, and Medicine (ISM) band. Second, this enabled easy fabrication of microwave transmission-line circuits (m/4 is roughly 40 mm) and reasonably easy hand-soldering of discrete components for termination and amplifier biasing. Operation at the 2.4-GHz ISM band for non-North American applications is a simple shift of frequency in the design targets, but the theory remains the same. DA - 2020/5// PY - 2020/5// DO - 10.1109/MMM.2020.2971184 VL - 21 IS - 5 SP - 136-145 SN - 1557-9581 KW - Impedance KW - Frequency measurement KW - Voltage-controlled oscillators KW - Noise measurement KW - Radar measurements KW - Power amplifiers ER - TY - JOUR TI - Interval based transmission contingency-constrained unit commitment for integrated energy systems with high renewable penetration AU - Liang, Junkai AU - Tang, Wenyuan T2 - INTERNATIONAL JOURNAL OF ELECTRICAL POWER & ENERGY SYSTEMS AB - As the reliance on natural gas to meet electric generation requirements increases, additional operational measures and risks must be considered to better understand the implications of the complex interdependency between the natural gas system and the power system. This paper develops a novel interval optimization framework of contingency-constrained unit commitment for integrated energy systems. Uncertainties in contingencies are captured by interval numbers, which reduces the computational burden compared with other uncertainty representations. Moreover, we incorporate the risk preferences of decision makers in the framework to alleviate the conservativeness of solutions. It is observed that power-to-gas technology can reduce renewable curtailment and offer auxiliary services. Numerical results demonstrate the economic value of power-to-gas in integrated energy systems. DA - 2020/7// PY - 2020/7// DO - 10.1016/j.ijepes.2020.105853 VL - 119 SP - SN - 1879-3517 KW - Contingency-constrained unit commitment KW - Integrated energy system KW - Interval optimization KW - Power-to-gas ER - TY - JOUR TI - 28 GHz mmWave Channel Measurements and Modeling in a Library Environment AU - Erden, Fatih AU - Ozdemir, Ozgur AU - Guvenc, Ismail T2 - 2020 IEEE Radio and Wireless Symposium (RWS) AB - To fully exploit the millimeter-wave bands for the fifth generation cellular systems, an accurate understanding of the channel propagation characteristics is required, and hence extensive measurement campaigns in different environments are needed. In this paper, we use a rotated directional antenna-based channel sounder for measurements at 28 GHz in large indoor environments at a library setting. We present models for power angular-delay profile and large-scale path loss based on the measurements over distances ranging from 10 m to 50 m. In total, nineteen different line-of-sight (LOS) and non-line-of-sight (NLOS) scenarios are considered, including the cases where the transmitter and the receiver are placed on different floors. Results show that the close-in free space reference distance and the floating intercept path loss models both perform well in fitting the empirical data. The path loss exponent obtained for the LOS scenarios is found to be very close to that of the free space path loss model. DA - 2020/1// PY - 2020/1// DO - 10.1109/rws45077.2020.9050106 VL - 2020-January SP - 52-55 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85083202769&partnerID=MN8TOARS ER - TY - JOUR TI - Hierarchical Control for Virtual Oscillator Based Grid-Connected and Islanded Microgrids AU - Awal, M. A. AU - Yu, Hui AU - Tu, Hao AU - Lukic, Srdjan M. AU - Husain, Iqbal T2 - IEEE TRANSACTIONS ON POWER ELECTRONICS AB - Virtual oscillator control (VOC) is a nonlinear time domain controller that achieves significantly faster primary control response in islanded microgrids, compared to droop or virtual synchronous machine (VSM) control. Despite its superior performance, adoption of VOC is limited due to the lack of compatible secondary regulation or grid synchronization techniques. This is attributed to the nonlinear nature of VOC that complicates secondary control design, and the third-harmonic component in VOC output voltage that severely restricts grid-tied operation. To leverage the faster primary control response characteristics of VOC, we propose a compatible hierarchical control structure that enables operation and seamless transition between islanded and grid-connected modes. In the islanded mode, the controller achieves voltage and frequency regulation and grid synchronization; in the grid-tied mode, notch filters are used to suppress harmonic currents and tertiary level power reference tracking is achieved. The proposed controllers are validated through a series of real-time hardware-in-the-loop tests and hardware experiments using laboratory inverter prototype and state-of-the-art controls and communications hardware. DA - 2020/1// PY - 2020/1// DO - 10.1109/TPEL.2019.2912152 VL - 35 IS - 1 SP - 988-1001 SN - 1941-0107 KW - Grid synchronization KW - hierarchical control KW - microgrid KW - secondary control KW - virtual oscillator control (VOC) ER - TY - JOUR TI - Sequence Generative Adversarial Networks for Wind Power Scenario Generation AU - Liang, Junkai AU - Tang, Wenyuan T2 - IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS AB - With the rapid increase in distributed wind generation, considerable efforts have been devoted to the microgrid day-ahead scheduling. The effectiveness of those methods will highly depend on the selection of the uncertainty sets. We propose a distribution-free approach for wind power scenario generation, using sequence generative adversarial networks. To capture the temporal correlation, the model adopts the long short-term memory architecture and uses generative adversarial networks coupled with reinforcement learning, which, in contrast to the existing methods, avoids manual labeling and captures the complex dynamics of the weather. We conduct case studies based on the data from the Bonneville Power Administration and the National Renewable Energy Laboratory, and show that the generated scenarios can better characterize the variability of wind power and reduce the risk of uncertainties, compared with those produced by Gaussian distribution, vanilla long short-term memory, and multivariate kernel density estimation. Moreover, the proposed method achieves better performance when applied to the day-ahead scheduling of microgrids. DA - 2020/1// PY - 2020/1// DO - 10.1109/JSAC.2019.2952182 VL - 38 IS - 1 SP - 110-118 SN - 1558-0008 KW - Deep learning KW - generative models KW - renewable energy integration KW - scenario generation ER - TY - JOUR TI - Distributed, Neurodynamic-Based Approach for Economic Dispatch in an Integrated Energy System AU - Yi, Zhongkai AU - Xu, Yinliang AU - Hu, Jiefeng AU - Chow, Mo-Yuen AU - Sun, Hongbin T2 - IEEE TRANSACTIONS ON INDUSTRIAL INFORMATICS AB - In an integrated energy system, the growing number of distributed heat and electric power generation units will bring new technical challenges to the existing centralized economic dispatch strategies. This paper proposes a distributed optimization approach for the economic system operation in a multienergy system by considering various equality and inequality constraints to accommodate the integration of intermittent renewable generations. The proposed distributed neurodynamic-based approach only requires the information exchange among neighboring units and offers flexibility, adaptivity, scalability, faster convergence, and lower communication burden compared with some traditional centralized methods. The simulation results of two integrated energy systems validate the effectiveness of the proposed distributed approach. Comparisons with other centralized and distributed optimization methods quantify the advantages of the proposed distributed approach in terms of convergence speed and computation complexity. DA - 2020/4// PY - 2020/4// DO - 10.1109/TII.2019.2905156 VL - 16 IS - 4 SP - 2245-2257 SN - 1941-0050 KW - Cogeneration KW - Resistance heating KW - Pipelines KW - Economics KW - Power systems KW - Optimization KW - Water heating KW - Combined heat and power (CHP) unit KW - distributed optimization KW - economic dispatch KW - integrated energy system (IES) KW - neurodynamic-based approach ER - TY - JOUR TI - Passivity-Based Predictive-Resonant Current Control for Resonance Damping in LCL-Equipped VSCs AU - Awal, M. A. AU - Yu, Wensong AU - Husain, Iqbal T2 - IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS AB - In this article, we propose a frequency-domain passivity-based damping controller combined with predictive current control for LCL-filter-equipped voltage source converters (VSCs) connected to an arbitrary ac network to achieve passive VSC input admittance almost up to the Nyquist frequency. The controller guarantees resonance damping in the corresponding frequency range irrespective of the network impedance seen by the VSC. Resonant current compensation is added to eliminate the steady-state tracking error and to achieve superior disturbance rejection. We have used impedance-based method for the analysis of harmonic resonance instabilities caused by current controllers. The developed passivity-based predictive-resonant current controller is analytically shown to stabilize interactions among multiparalleled VSCs. Resonance damping capability of the proposed method is validated through simulation and hardware experiments. DA - 2020/// PY - 2020/// DO - 10.1109/TIA.2019.2959594 VL - 56 IS - 2 SP - 1702-1713 SN - 1939-9367 KW - Active damping KW - admittance KW - current control KW - passivity KW - predictive control KW - resonance KW - stability ER - TY - JOUR TI - Dynamic Wireless Charging: Reflexive Field Containment Using Saturable Inductors AU - Dayerizadeh, Alireza AU - Feng, Hao AU - Lukic, Srdjan M. T2 - IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS AB - In dynamic wireless charging applications, segmented transmitter coils transfer power to a moving receiver coil. This article proposes a method in which the field strength in coupled transmitter coils automatically adjusts based on the position of the receiver. Specifically, a saturable inductor is applied to provide a high uncompensated inductive reactance in the uncoupled condition. By exploiting the reflected reactance as the system approaches the maximum coupled condition, the inductor saturates and the field strength in the coupled transmitter coils automatically increases. The field strength is at its peak when the transmitting and receiving coils reach their maximum coupling and sharply decreases when the receiver is decoupled from the transmitter. Consequently, the difference between the coupled and uncoupled currents in the transmitter coil is maximized, resulting in a near six-fold improvement in field containment performance compared to previously reported findings. This allows for system-level efficient power transfer and compliance with electromagnetic emission standards without complex shielding circuits and auxiliary active position detection approaches. We present the analysis, design criteria of the compensation network, and experimental validation for the proposed method. DA - 2020/// PY - 2020/// DO - 10.1109/TIA.2020.2964215 VL - 56 IS - 2 SP - 1784-1792 SN - 1939-9367 UR - https://doi.org/10.1109/TIA.2020.2964215 KW - Dynamic wireless power transfer KW - inductive power transfer KW - saturable inductor KW - wireless power transfer ER - TY - JOUR TI - Optimization of an intrinsic coincident polarimeter and quantitative architectural comparison of different polarimeter techniques AU - Yang, Ruonan AU - Sen, Pratik AU - O'Connor, Brendan AU - Kudenov, Michael T2 - OPTICAL ENGINEERING AB - Polarimeters have broad applications in remote sensing, astronomy, and biomedical imaging to measure a scene’s polarization state. An intrinsic coincident (IC) full-Stokes polarimeter was previously demonstrated and optimized to achieve high temporal and spatial resolution. We optimized the IC polarimeter by introducing additional waveplates or measurement channels and compared it with existing polarimeter architectures under signal-independent Gaussian noise and signal-dependent Poisson noise. The quantitative comparison of noise variances showed that the IC and division-of-amplitude polarimeters have the lowest noise variances due to their higher signal collection ability. Both polarimeters have a factor of 2 and 2 improved signal-to-noise ratio, in the S0 component, for Gaussian and Poisson noises, respectively, as compared to division of time, division of focal plane, and division of aperture polarimeters. While the division of amplitude and IC polarimeters outperforms other approaches, the IC polarimeter has a significantly simpler design, potentially allowing for cost-effective, high-performance polarimetric imaging. DA - 2020/2// PY - 2020/2// DO - 10.1117/1.OE.59.2.024111 VL - 59 IS - 2 SP - SN - 1560-2303 KW - polarimetry KW - polarimetric imaging KW - polarization-selective devices KW - optimization KW - signal-to-noise ratio ER - TY - JOUR TI - Differential Privacy for Network Identification AU - Katewa, Vaibhav AU - Chakrabortty, Aranya AU - Gupta, Vijay T2 - IEEE TRANSACTIONS ON CONTROL OF NETWORK SYSTEMS AB - We consider a multiagent linear time-invariant system whose dynamical model may change from one disturbance event to another. The system is monitored by a control center that collects output measurements from the agents after every event and estimates the eigenvalues of the model to keep track of any adverse impact of the disturbance on its spectral characteristics. Sharing measurements in this way, however, can be susceptible to privacy breaches. If an intruder gains access to these measurements, she may estimate the values of sensitive model parameters and launch more severe attacks. To prevent this, we employ a differential privacy framework by which agents can add synthetic noise to their measurements before sending them to the control center. The noise is designed carefully by characterizing the sensitivity of the system so that it limits the intruder from inferring any incremental change in the sensitive parameters, thereby protecting their privacy. Our numerical results show that the proposed design results in marginal degradation in eigenvalue estimation when compared to the error incurred by the intruder in identifying the sensitive parameters. DA - 2020/3// PY - 2020/3// DO - 10.1109/TCNS.2019.2922169 VL - 7 IS - 1 SP - 266-277 SN - 2372-2533 KW - Cyber-security KW - differential privacy (DP) KW - monitoring KW - multiagent system KW - topology identification ER - TY - JOUR TI - Asymmetric Bar Winding for High-Speed Traction Electric Machines AU - Islam, Md Sariful AU - Husain, Iqbal AU - Ahmed, Adeeb AU - Sathyan, Anand T2 - IEEE TRANSACTIONS ON TRANSPORTATION ELECTRIFICATION AB - A new asymmetric bar winding concept along with the analysis and benefits for high-speed traction electric machines is presented. The objective is to reduce the ac losses, especially at high speeds, utilizing optimized and asymmetric conductor heights within a slot for bar-wound stators. Detailed winding diagram, height optimization, ac loss analysis, and thermal performance are presented for both symmetric, i.e., conventional, and asymmetric bar windings. The proposed idea is validated using the closed-form analytical equation and 2-D time-stepped finite-element analysis (FEA). A substantial reduction of ac losses and improvement in continuous power over the wide operation range is achieved as demonstrated for a 12-pole, 100-kW high-speed (15 000 r/min) PM traction machine. Thermal performance analysis using forced liquid cooling is also included. The design and analysis methodology is presented to support high-speed traction electric machine designers meet the ever-increasing demand on efficiency and performance with bar-type windings. DA - 2020/3// PY - 2020/3// DO - 10.1109/TTE.2019.2962329 VL - 6 IS - 1 SP - 3-15 SN - 2332-7782 KW - Conductors KW - Bars KW - Windings KW - Air gaps KW - Resistance KW - Stators KW - AC losses KW - ac resistance factor KW - bar-wound stator KW - hairpin winding KW - IPMSM KW - liquid cooling KW - proximity effect KW - skin effect ER - TY - JOUR TI - Peace: Privacy-Preserving and Cost-Efficient Task Offloading for Mobile-Edge Computing AU - He, Xiaofan AU - Jin, Richeng AU - Dai, Huaiyu T2 - IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS AB - The limited information processing capability and battery life of mobile devices is becoming a bottleneck in delivering more advanced and high-quality services to the customers. To address this problem, the recently advocated mobile-edge computing (MEC) architecture is promising, where the essential idea is to bring the computation resource to the network edge and allow users to wirelessly offload resource demanding computation tasks to the nearby MEC servers for potentially faster execution and lower battery consumption. Nonetheless, the existing understanding of the privacy aspect of MEC is still far from complete. In this work, a user presence inference attack that invades user privacy by exploiting the feature tasks offloaded from users is identified for MEC. Existing privacy-preserving techniques developed for other applications cannot be applied to defeat this attack in MEC, as they may disrupt the optimal task offloading scheduling and cause severe degradation in user experience. With this consideration, a novel privacy-preserving and cost-efficient (PEACE) task offloading scheme that can preserve user privacy while still ensure the best possible user experience is developed in this work based on the generic Lyapunov optimization framework. The effectiveness of the proposed scheme is validated through both analysis and simulations. DA - 2020/3// PY - 2020/3// DO - 10.1109/TWC.2019.2958091 VL - 19 IS - 3 SP - 1814-1824 SN - 1558-2248 KW - Mobile-edge computing KW - privacy KW - task offloading KW - Lyapunov optimization ER - TY - JOUR TI - Engineering a Unified Dielectric Solution for AlGaN/GaN MOS-HFET Gate and Access Regions AU - Azam, Faisal AU - Tanneeru, Akhilesh AU - Lee, Bongmook AU - Misra, Veena T2 - IEEE TRANSACTIONS ON ELECTRON DEVICES AB - Typically GaN metal-oxide-semiconductor heterojunction-field-effect transistors (MOS-HFETs) have used two separate dielectrics for the gate and access regions. However, as this article shows, with proper gate-stack engineering, a unified dielectric solution can be achieved for the transistor. HfO 2 dielectrics were deposited by atomic layer deposition (ALD). Two types of oxidants were investigated, namely, water (H 2 O) and ozone (O 3 ). It was found that MOS-HFETs with O 3 oxidant yielded lower threshold voltage (VTH) shifts, higher maximum drain current (IDS,max) of 340 mA/mm, 20% lower ON-resistance (RON), higher peak transconductance at 112.66 mS/mm, lower hysteresis, and lower gate leakage (5.4 × 10 -6 A/cm 2 ) compared to water oxidant based MOS-HFETs with IDS,max of 240 mA/mm, 81.38 mS/mm peak transconductance, and 1.7 × 10 -4 A/cm 2 gate leakage. DC/RF dispersion tests showed MOS-HFETs with O 3 oxidant had -200x better current collapse recovery. Temperature characterization and reliability test results, such as high-temperature reverse bias (HTRB), are published for the first time on ALD-HfO 2 /AlGaN/GaN MOSHFETs using tetrakis(dimethylamino)hafnium (TDMAH) and O 3 precursor. Using an ozone oxidant provided more stability (i.e., less variability in RON and VTH) as a function of temperature. Finally, when devices were electrically stressed in the OFF-state, the HTRB test showed minimal VTH drift (<; 0.5 V) in the case of O 3 oxidant versus much larger VTH drift (2.5 V) in the case of H 2 O oxidant. DA - 2020/3// PY - 2020/3// DO - 10.1109/TED.2020.2969394 VL - 67 IS - 3 SP - 881-887 SN - 1557-9646 UR - https://doi.org/10.1109/TED.2020.2969394 KW - AlGaN/GaN KW - atomic layer deposition (ALD) KW - current collapse KW - HfO2 KW - high electron mobility transistor (HEMT) KW - high-k KW - high-temperature reverse bias (HTRB) KW - hydroxyl KW - interface KW - MOS KW - HFET KW - oxidant KW - reliability KW - traps ER - TY - JOUR TI - Advanced Wireless for Unmanned Aerial Systems: 5G Standardization, Research Challenges, and AERPAW Architecture AU - Marojevic, Vuk AU - Guvenc, Ismail AU - Dutta, Rudra AU - Sichitiu, Mihail L. AU - Floyd, Brian A. T2 - IEEE Vehicular Technology Magazine AB - The 5G mobile communications systems merge traditionally separate communications and networking systems and services to effectively support a myriad of heterogeneous applications. Researchers and industry working groups are investigating the integration of aerial nodes, shared spectrum techniques, and new network architectures, which are gradually being introduced into standards. This article discusses relevant standardization efforts for the integration of unmanned aerial systems (UASs) into 5G and the requirements for an aerial wireless testbed. We introduce the aerial experimentation and research platform for advanced wireless (AERPAW) and, specifically, its architecture, which is designed for enabling experimental research in controlled yet production-like environments. Sample research projects and trials show the critical R&D needs, broad scope, and impact that such a platform can have on technology evolution, regulation, and standardization as well as future services. DA - 2020/// PY - 2020/// DO - 10.1109/MVT.2020.2979494 VL - 15 IS - 2 SP - 22-30 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85083012374&partnerID=MN8TOARS KW - 5G mobile communication KW - Wireless communication KW - Software KW - Long Term Evolution KW - 3GPP KW - Three-dimensional displays ER - TY - JOUR TI - Minimizing the Polarization Leakage of Geometric-phase Coronagraphs with Multiple Grating Pattern Combinations AU - Doelman, David S. AU - Por, Emiel H. AU - Ruane, Garreth AU - Escuti, Michael J. AU - Snik, Frans T2 - PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC AB - The design of liquid-crystal diffractive phase plate coronagraphs for ground-based and space-based high-contrast imaging systems is limited by the trade-off between spectral bandwidth and polarization leakage. We demonstrate that by combining phase patterns with a polarization grating (PG) pattern directly followed by one or several separate PGs, we can suppress the polarization leakage terms by additional orders of magnitude by diffracting them out of the beam. Using two PGs composed of a single-layer liquid crystal structure in the lab, we demonstrate a leakage suppression of more than an order of magnitude over a bandwidth of 133 nm centered around 532 nm. At this center wavelength we measure a leakage suppression of three orders of magnitude. Furthermore, simulations indicate that a combination of two multi-layered liquid-crystal PGs can suppress leakage to <10−5 for 1–2.5 μm and <10−10 for 650–800 nm. We introduce multi-grating solutions with three or more gratings that can be designed to have no separation of the two circular polarization states, and offer even deeper suppression of polarization leakage. We present simulations of a triple-grating solution that has <10−10 leakage on the first Airy ring from 450 to 800 nm. We apply the double-grating concept to the Vector-vortex coronagraph of charge 4, and demonstrate in the lab that polarization leakage no longer limits the on-axis suppression for ground-based contrast levels. Lastly, we report on the successful installation and first-light results of a double-grating vector Apodizing Phase Plate pupil-plane coronagraph installed at the Large Binocular Telescope. We discuss the implications of these new coronagraph architectures for high-contrast imaging systems on the ground and in space. DA - 2020/4// PY - 2020/4// DO - 10.1088/1538-3873/ab755f VL - 132 IS - 1010 SP - SN - 1538-3873 KW - instrumentation KW - high angular resolution KW - planets and satellites KW - detection KW - techniques KW - high angular resolution ER - TY - JOUR TI - The Single-mode Complex Amplitude Refinement (SCAR) coronagraph: II. Lab verification, and toward the characterization of Proxima b AU - Haffert, S. Y. AU - Por, E. H. AU - Keller, C. U. AU - Kenworthy, M. A. AU - Doelman, D. S. AU - Snik, F. AU - Escuti, M. J. T2 - ASTRONOMY & ASTROPHYSICS AB - We present the monochromatic lab verification of the newly developed SCAR coronagraph that combines a phase plate (PP) in the pupil with a microlens-fed single-mode fiber array in the focal plane. The two SCAR designs that have been measured, create respectively a 360 degree and 180 degree dark region from 0.8 – 2.4 λ ∕ D around the star. The 360 SCAR has been designed for a clear aperture and the 180 SCAR has been designed for a realistic aperture with central obscuration and spiders. The 360 SCAR creates a measured stellar null of 2 – 3 × 10 −4 , and the 180 SCAR reaches a null of 1 × 10 −4 . Their monochromatic contrast is maintained within a range of ±0.16 λ ∕ D peak-to-valley tip-tilt, which shows the robustness against tip-tilt errors. The small inner working angle and tip-tilt stability makes the SCAR coronagraph a very promising technique for an upgrade of current high-contrast instruments to characterize and detect exoplanets in the solar neighborhood. DA - 2020/3/9/ PY - 2020/3/9/ DO - 10.1051/0004-6361/201731615 VL - 635 SP - SN - 1432-0746 KW - instrumentation: high angular resolution KW - instrumentation: spectrographs KW - techniques: high angular resolution KW - techniques: imaging spectroscopy ER - TY - JOUR TI - Detection of driver manual distraction via image-based hand and ear recognition AU - Li, Li AU - Zhong, Boxuan AU - Hutmacher, Clayton, Jr. AU - Liang, Yulan AU - Horrey, William J. AU - Xu, Xu T2 - ACCIDENT ANALYSIS AND PREVENTION AB - Driving distraction is a leading cause of fatal car accidents, and almost nine people are killed in the US each day because of distracting activities. Therefore, reducing the number of distraction-affected traffic accidents remains an imperative issue. A novel algorithm for detection of drivers’ manual distraction was proposed in this manuscript. The detection algorithm consists of two modules. The first module predicts the bounding boxes of the driver's right hand and right ear from RGB images. The second module takes the bounding boxes as input and predicts the type of distraction. 106,677 frames extracted from videos, which were collected from twenty participants in a driving simulator, were used for training (50%) and testing (50%). For distraction classification, the results indicated that the proposed framework could detect normal driving, using the touchscreen, and talking with a phone with F1-score 0.84, 0.69, 0.82, respectively. For overall distraction detection, it achieved F1-score of 0.74. The whole framework ran at 28 frames per second. The algorithm achieved comparable overall accuracy with similar research, and was more efficient than other methods. A demo video for the algorithm can be found at https://youtu.be/NKclK1bHRd4. DA - 2020/3// PY - 2020/3// DO - 10.1016/j.aap.2020.105432 VL - 137 SP - SN - 1879-2057 KW - Driving distraction KW - Upper extremity kinematics KW - Deep learning KW - Computer vision KW - Multi-class classification ER - TY - JOUR TI - PFR ancillary service in low-inertia power system AU - Li, Weifeng AU - Du, Pengwei AU - Lu, Ning T2 - IET GENERATION TRANSMISSION & DISTRIBUTION AB - A high level of renewable resource penetration could lead to displacement of conventional synchronous generators from dispatch, and consequently, reduce the system inertia. The decline in the system inertia will increase the primary frequency response (PFR) need requiring to maintain grid frequency stability. This study proposes a new market design to co-optimise energy, inertia and PFR while considering uncertainties in renewable energy productions. A full dynamic model of Electric Reliability Council of Texas (ERCOT) interconnection is used to quantify the PFR requirement for the system inertia. The proposed method explicitly incorporates frequency dynamics and uncertainties in energy production from renewable resources in the scheduling process, which is formulated as a stochastic unit commitment problem. A case study of ERCOT grid demonstrated that the proposed stochastic scheduling of energy, inertia and PFR could yield a more cost-effective solution than the traditional deterministic formulation for the grids with a high penetration of renewable resources. DA - 2020/3/13/ PY - 2020/3/13/ DO - 10.1049/iet-gtd.2019.1536 VL - 14 IS - 5 SP - 920-930 SN - 1751-8695 KW - renewable energy sources KW - synchronous generators KW - scheduling KW - stochastic processes KW - power generation dispatch KW - power system reliability KW - power generation scheduling KW - power grids KW - power markets KW - frequency response KW - PFR ancillary service KW - low-inertia power system KW - renewable resource penetration KW - conventional synchronous generators KW - system inertia KW - primary frequency response KW - grid frequency stability KW - renewable energy productions KW - PFR requirement KW - frequency dynamics KW - energy production KW - renewable resources ER - TY - JOUR TI - Observing relaxation in device quality InGaN templates by TEM techniques AU - Eldred, Tim B. AU - Abdelhamid, Mostafa AU - Reynolds, J. G. AU - El-Masry, N. A. AU - LeBeau, James M. AU - Bedair, S. M. T2 - APPLIED PHYSICS LETTERS AB - Device quality InGaN templates are synthesized using the semibulk (SB) approach. The approach maintains the film's 2D growth and avoids the formation of indium-metal inclusions. The strain relaxation processes of the grown InxGa1−xN templates are accompanied by variations in the indium content (x) and lattice parameters (a and c) across the InGaN template's thickness as the residual strain is continuously decreasing. This strain and lattice parameters' variation creates difficulties in applying standard x-ray Diffraction (XRD) and Reciprocal Space mapping (RSM) techniques to estimate the residual strain and the degree of the elastic strain relaxation. We used high-resolution High-angle annular dark-field scanning transmission electron microscopy and Energy-dispersive x-ray spectroscopy (EDS) to monitor the variations of the indium content, lattice parameters, and strain relaxation across the growing InxGa1−xN templates. We show that strain relaxation takes place by V-pit defect formation. Some of these V-pits are refilled by the GaN interlayers in the InxGa1−xN SB templates, while others propagate to the template surface. We present an alternative approach combining photoluminescence (PL) and EDS for estimating the degree of strain relaxation in these InxGa1−xN templates. The values obtained for the degree of relaxation estimated from TEM studies and PL measurements are within reasonable agreement in this study. Device quality InxGa1−xN templates with x ∼ 0.08, with a degree of relaxation higher than 70%, are achieved. DA - 2020/3/9/ PY - 2020/3/9/ DO - 10.1063/1.5139269 VL - 116 IS - 10 SP - SN - 1077-3118 ER - TY - JOUR TI - 1.2-kV 4H-SiC SenseFET With Monolithically Integrated Sensing Resistor AU - Han, Kijeong AU - Baliga, B. J. T2 - IEEE ELECTRON DEVICE LETTERS AB - A 1.2 kV rated 4H-SiC SenseFET structure with monolithically integrated sensing resistor is proposed and experimentally demonstrated. The SenseFET was fabricated on a 6-inch SiC wafer using the same fabrication process as the conventional MOSFET, where Tungsten-Silicided (WSi 2 ) Poly-Si layer was patterned to form the Poly-Si gate and sensing resistor, R S , simultaneously. No impact of the integration of the Sense MOSFET and sense resistor on blocking characteristics was confirmed. Good linearity (within ±10%) of the sense voltage with main MOSFET drain current was observed, independent of drain current level, gate bias voltage, and temperature. DA - 2020/3// PY - 2020/3// DO - 10.1109/LED.2020.2964773 VL - 41 IS - 3 SP - 437-440 SN - 1558-0563 KW - Silicon carbide KW - 4H-SiC KW - MOSFET KW - SenseFET KW - monolithically integrated KW - sensing resistor KW - sensing voltage ER - TY - JOUR TI - Implementing an Electric Utility Microgrid: Lessons learned AU - Vukojevic, Aleksandar AU - Lukic, Srdjan AU - White, Leonard W. T2 - IEEE ELECTRIFICATION MAGAZINE AB - Microgrids are nascent, with many lessons still to be learned. Work at Mount Holly has shown that microgrids may not follow common design or standard algorithms. Protection, transformers, grounding, operations, fault detection, and islanding all require attention to detail and may not operate in the manner the toolset currently in use indicates they should. DA - 2020/3// PY - 2020/3// DO - 10.1109/MELE.2019.2962887 VL - 8 IS - 1 SP - 24-36 SN - 2325-5889 KW - Microgrids KW - Grounding KW - Circuit faults KW - Oil insulation KW - Power transformer insulation KW - Fault currents KW - Surge protection KW - Electricity supply industry ER - TY - JOUR TI - Sustainable community based PV-storage planning using the Nash bargaining solution AU - Liang, Junkai AU - Shirsat, Ashwin AU - Tang, Wenyuan T2 - INTERNATIONAL JOURNAL OF ELECTRICAL POWER & ENERGY SYSTEMS AB - A dramatic increase in the penetration of customer-sited solar and storage has increased the concerns over utility revenues. A novel business model where the utility and the households within a community cooperatively deploy solar and storage is proposed in this paper. The potential increased payoffs are allocated by the Nash bargaining solution with efficiency and symmetry. Community-based expansion planning highly relies on local meteorology and geography. A convolutional neural network based scenario generation method is used to capture the locally driven uncertainties. The numerical results demonstrate that the players can improve their payoffs using the cooperative approach as compared to the non-cooperative approach. The case studies shed light on the future customer-utility relationship. DA - 2020/6// PY - 2020/6// DO - 10.1016/j.ijepes.2019.105759 VL - 118 SP - SN - 1879-3517 KW - Cooperative game KW - Nash bargaining solution KW - PV-storage expansion planning KW - Scenario generation KW - Zero-energy community ER - TY - JOUR TI - Flexible thermoelectric generators for body heat harvesting - Enhanced device performance using high thermal conductivity elastomer encapsulation on liquid metal interconnects AU - Sargolzaeiaval, Yasaman AU - Ramesh, Viswanath Padmanabhan AU - Neumann, Taylor V AU - Misra, Veena AU - Vashaee, Daryoosh AU - Dickey, Michael D. AU - Ozturk, Mehmet C. T2 - APPLIED ENERGY AB - This paper reports flexible thermoelectric generators (TEGs) employing eutectic gallium indium (EGaIn) liquid metal interconnects encased in a novel, high thermal conductivity (HTC) elastomer. These TEGs are part of a broader effort to harvest thermal energy from the body and convert it into electrical energy to power wearable electronics. The flexible TEGs reported in this paper employ the same thermoelectric legs' used in rigid TEGs, thus eliminating the need to develop new materials specifically for flexible TEGs that often sacrifice the so-called figure of merit' for flexibility. Flexible TEGs reported here embed rigid thermoelectric legs' in soft and flexible packaging, using stretchable EGaIn interconnects. The use of liquid metal interconnects provides ultimate stretchability and low electrical resistance between the thermoelectric legs. The liquid metal lines are encased in a new stretchable silicone elastomer doped with both graphene nano-platelets and EGaIn to increase its thermal conductivity. This high thermal conductivity elastomer not only reduces the parasitic thermal resistance of the encapsulation layer but it also serves as a heat spreader, leading to 1.7X improvement in the output power density of TEGs compared to devices fabricated with a conventional elastomer. The device performance is further improved by a thin Cu layer acting as a heat spreader providing an additional 1.3X enhancement in the output power at 1.2 m/s air velocity (typical walking speed). Worn on the wrist, our best devices achieve power levels in excess of 30 μW/cm2 at an air velocity of 1.2 m/s outperforming previously reported flexible TEGs. DA - 2020/3/15/ PY - 2020/3/15/ DO - 10.1016/j.apenergy.2019.114370 VL - 262 SP - SN - 1872-9118 KW - Thermoelectric generators KW - Body heat harvesters KW - Flexible electronics KW - Thermally conductive polymers ER - TY - JOUR TI - Correction of Channel Sounding Clock Drift and Antenna Rotation Effects for mmWave Angular Profile Measurements AU - Erden, Fatih AU - Ozdemir, Ozgur AU - Khawaja, Wahab AU - Guvenc, Ismail T2 - IEEE OPEN JOURNAL OF ANTENNAS AND PROPAGATION AB - Proper characterization of the millimeter-wave (mmWave) propagation channel requires measuring the power angular-delay profile of the channel which includes angle-of-departure and angle-of-arrival of the multipath components (MPCs). In this paper, we first describe in detail our rotating directional antennas-based 28 GHz channel sounder. Then, for this specific sounder class, we describe and address the following two problems in extracting the MPCs from the measurements: 1) For long-distance channel measurements, triggering signal cannot be generated for the TX and the RX using a single clock (SICL). This necessitates the use of separate clocks (SECLs) which introduces a random timing drift between the clocks. 2) As positions of the antennas change during scanning, total distance traveled by the same MPC differs at each measurement. These problems together cause missing some of the MPCs and detecting MPCs that do not exist in reality. We propose an algorithm to correct the clock drift and MPC delay errors due to the rotation of the antennas. We compare the MPCs from the SICL measurement and the corrected SECL measurements using a Hungarian algorithm based MPC matching method. We show that the percentage of the matched MPCs increases from 28.36% to 74.13% after the correction process. DA - 2020/// PY - 2020/// DO - 10.1109/OJAP.2020.2979243 VL - 1 SP - 71-87 SN - 2637-6431 UR - https://doi.org/10.1109/OJAP.2020.2979243 KW - 28 GHz KW - channel sounding KW - clock drift KW - Hungarian algorithm KW - millimeter-wave (mmWave) KW - multipath component (MPC) ER - TY - JOUR TI - Guest Editorial: WBG semiconductor power electronics for industrial and automotive applications AU - Wang, Jun AU - Huang, Alex Q. AU - Blaabjerg, Frede AU - Ruan, Xinbo AU - Mertens, Axel AU - Ji, Bing T2 - IET POWER ELECTRONICS DA - 2020/2/19/ PY - 2020/2/19/ DO - 10.1049/iet-pel.2020.0051 VL - 13 IS - 3 SP - 391-393 SN - 1755-4543 ER - TY - JOUR TI - Wearable multiplexed biosensor system toward continuous monitoring of metabolites AU - Yokus, Murat A. AU - Songkakul, Tanner AU - Pozdin, Vladimir A. AU - Bozkurt, Alper AU - Daniele, Michael A. T2 - BIOSENSORS & BIOELECTRONICS AB - Comprehensive metabolic panels are the most reliable and common methods for monitoring general physiology in clinical healthcare. Translation of this clinical practice to personal health and wellness tracking requires reliable, non-invasive, miniaturized, ambulatory, and inexpensive systems for continuous measurement of biochemical analytes. We report the design and characterization of a wearable system with a flexible sensor array for non-invasive and continuous monitoring of human biochemistry. The system includes signal conditioning, processing, and transmission parts for continuous measurement of glucose, lactate, pH, and temperature. The system can operate three discrete electrochemical cells. The system draws 15 mA under continuous operation when powered by a 3.7 V 150 mAh battery. The analog front-end of the electrochemical cells has four potentiostats and three multiplexers for multiplexed and parallel readout from twelve working electrodes. Utilization of redundant working electrodes improves the measurement accuracy of sensors by averaging chronoamperometric responses across the array. The operation of the system is demonstrated in vitro by simultaneous measurement of glucose and lactate, pH, and skin temperature. In benchtop measurements, the sensors are shown to have sensitivities of 26.31 μA mM-1·cm-2 for glucose, 1.49 μA mM-1·cm-2 for lactate, 54 mV·pH-1 for pH, and 0.002 °C-1 for temperature. With the custom wearable system, these values were 0.84 ± 0.03 mV μM-1·cm-2 or glucose, 31.87 ± 9.03 mV mM-1·cm-2 for lactate, 57.18 ± 1.43 mV·pH-1 for pH, and 63.4 μV·°C-1 for temperature. This miniaturized wearable system enables future evaluation of temporal changes of the sweat biomarkers. DA - 2020/4/1/ PY - 2020/4/1/ DO - 10.1016/j.bios.2020.112038 VL - 153 SP - SN - 1873-4235 KW - Wearable KW - Multiplex KW - Potentiostat KW - Electrochemical sensors KW - Glucose KW - Lactate KW - pH KW - Sweat sensors ER - TY - JOUR TI - A new method for Volt-Var optimization with conservation voltage reduction on distribution systems AU - Ozdemir, Gulcihan AU - Baran, Mesut T2 - ELECTRICAL ENGINEERING DA - 2020/3// PY - 2020/3// DO - 10.1007/s00202-020-00945-4 VL - 102 IS - 1 SP - 493-502 SN - 1432-0487 KW - Energy conservation KW - Energy efficiency KW - Power management KW - Reactive power control KW - Voltage control ER - TY - JOUR TI - Distributed Power Management for Networked AC-DC Microgrids With Unbalanced Microgrids AU - Zhou, Jianguo AU - Xu, Yinliang AU - Sun, Hongbin AU - Li, Yushuai AU - Chow, Mo-Yuen T2 - IEEE TRANSACTIONS ON INDUSTRIAL INFORMATICS AB - This paper investigates the issue of power management networked ac-dc microgrids (MGs) interconnected by interlinking converters with the consideration of unbalanced single-/three-phase ac MGs as well as power quality improvement. An integrated hierarchical distributed coordinated control approach is developed, which mainly consists of an up-layer event-triggered method of power sharing among MGs, and an event-triggered dynamic power flow routing approach to navigate the power flow among phases of the single-/three-phase ac MGs to balance the power of the MG. With the proposed control method, balanced output phase powers for the three-phase distributed generation (DGs) and enhanced voltage quality at the point of common coupling and DG terminals can be achieved besides proportional active power sharing among MGs and reduced communication. Simulation results are presented to demonstrate the proposed control method. DA - 2020/3// PY - 2020/3// DO - 10.1109/TII.2019.2925133 VL - 16 IS - 3 SP - 1655-1667 SN - 1941-0050 KW - Integrated circuits KW - Power quality KW - Microgrids KW - Voltage control KW - Informatics KW - Reactive power KW - Harmonic analysis KW - Coordinated power management KW - distributed control KW - event-triggered control KW - networked ac-dc microgrids (MGs) KW - power quality improvement KW - single- KW - three-phase MG ER - TY - JOUR TI - Coverage Enhancement for NLOS mmWave Links Using Passive Reflectors AU - Khawaja, Wahab AU - Ozdemir, Ozgur AU - Yapici, Yavuz AU - Erden, Fatih AU - Guvenc, Ismail T2 - IEEE OPEN JOURNAL OF THE COMMUNICATIONS SOCIETY AB - The future 5G networks are expected to use millimeter wave (mmWave) frequency bands to take advantage of the large unused spectrum. However, due to the high path loss at mmWave frequencies, coverage of mmWave signals can get severely reduced, especially for non-line-of-sight (NLOS) scenarios as mmWave signals are severely attenuated when going through obstructions. In this work, we study the use of passive metallic reflectors of different shapes/sizes to improve 28 GHz mmWave signal coverage for both indoor and outdoor NLOS scenarios. We quantify the gains that can be achieved in the link quality with metallic reflectors using measurements, analytical expressions, and ray tracing simulations. In particular, we provide an analytical model for the end-to-end received power in an NLOS scenario using reflectors of different shapes and sizes. For a given size of the flat metallic sheet reflector approaching to the size of the incident beam, we show that the reflected received power for the NLOS link is the same as line-of-sight (LOS) free space received power of the same link distance. Extensive results are provided to study the impact of environmental features and reflector characteristics on NLOS link quality. DA - 2020/// PY - 2020/// DO - 10.1109/OJCOMS.2020.2969751 VL - 1 SP - 263-281 SN - 2644-125X UR - https://doi.org/10.1109/OJCOMS.2020.2969751 KW - Coverage KW - indoor KW - mmWave KW - non-line-of-sight (NLOS) KW - outdoor KW - PXI KW - ray tracing (RT) KW - reflector ER - TY - JOUR TI - Estimation, Minimization, and Validation of Commutation Loop Inductance for a 135-kW SiC EV Traction Inverter AU - Moorthy, Radha Sree Krishna AU - Aberg, Bryce AU - Olimmah, Marshal AU - Yang, Li AU - Rahman, Dhrubo AU - Lemmon, Andrew N. AU - Yu, Wensong AU - Husain, Iqbal T2 - IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS AB - With growing interests in low-inductance silicon carbide (SiC)-based power module packaging, it is vital to focus on system-level design aspects to facilitate easy integration of the modules and reap system-level benefits. To effectively utilize the low-inductance modules, busbar and interconnects should also be designed with low stray inductances. A holistic investigation of the flux path and flux cancellations in the module-busbar assembly, which can be treated as differentially coupled series inductors, is thus mandatory for a system-level design. This article presents a busbar design, which can be adopted to effectively integrate the CREE's low-inductance 1.2-/1.7-kV SiC power modules. This article also proposes a novel measurement technique to measure the inductance of the module-busbar assembly as a whole rather than deducing it from individual components. The inductance of the overall commutation loop of the inverter that encompasses the SiC power module, interconnects, and printed circuit board (PCB) busbar has been estimated using finite-element analysis (FEA). Insights gained from FEA provided the guidelines to decide the placement of the decoupling capacitors in the busbar to minimize the overall commutation loop inductance from 12.8 to 7.4 nH, which resulted in a significant reduction in the device voltage overshoot. The simulation results have been validated through measurements using an impedance analyzer (ZA) with less than 5% difference between the extracted loop inductance from FEA and measurements. The busbar design study and the measurement technique discussed in this article can be easily extended to other power module packages. Finally, the 135-kW inverter has been compared to a similar high-power inverter utilizing a laminated busbar to highlight the performance of the former. DA - 2020/3// PY - 2020/3// DO - 10.1109/JESTPE.2019.2952884 VL - 8 IS - 1 SP - 286-297 SN - 2168-6785 KW - Ansys Q3D extractor KW - commutation loop inductance KW - electric vehicles (EVs) KW - impedance measurement KW - parasitic extraction KW - printed circuit board (PCB) busbar KW - silicon carbide (SiC) KW - wide-bandgap (WBG) devices ER - TY - JOUR TI - High performance flexible supercapacitors including redox active molybdate incorporated Poly(vinylphosphonic acid) hydrogels AU - Cevik, E. AU - Bozkurt, A. AU - Dirican, M. AU - Zhang, X. T2 - INTERNATIONAL JOURNAL OF HYDROGEN ENERGY AB - Novel gel polymer electrolyte (hydrogel) was prepared by incorporation of poly (vinylphosphonic acid) (PVPA) as a host matrix and redox active ammonium molybdate, Mo. Supercapacitors including active carbon electrodes were fabricated using hydrogels, PVPA/MoX where X represents the percent fraction of Mo in PVPA. All the electrolytes were in gel form and show excellent bending and stretching properties in a device. The electrochemical performance of the devices was investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) experiments. Surprisingly, the specific capacitance (Cs) of the device increased to 1276 F g−1 which is at least 50 times enhancement by introducing Mo as mediator compared to the PVPA based system. The supercapacitor with PVPA/Mo10 has the highest energy density of 180.2 Wh kg−1 at a power density of 500 W kg−1. The device with the same hydrogel structure exhibited higher performance after 2300 charge-discharge cycles and the maintained 85% of its initial capacitance performance. A supercapacitor was fabricated using PVPA/Mo10 and tested under bent and twisted conditions confirming remarkable capacitance retention. DA - 2020/1/13/ PY - 2020/1/13/ DO - 10.1016/j.ijhydene.2019.11.025 VL - 45 IS - 3 SP - 2186-2194 SN - 1879-3487 KW - Flexible supercapacitors KW - Molybdate KW - Poly(vinylphosphonic acid) KW - Hydrogel electrolyte KW - Redox mediated supercapacitor ER - TY - JOUR TI - Thermal conductivity of ultra-wide bandgap thin layers - High Al-content AlGaN and beta-Ga2O3 AU - Tran, Dat Q. AU - Blumenschein, Nicholas AU - Mock, Alyssa AU - Sukkaew, Pitsiri AU - Zhang, Hengfang AU - Muth, John F. AU - Paskova, Tania AU - Paskov, Plamen P. AU - Darakchieva, Vanya T2 - PHYSICA B-CONDENSED MATTER AB - Transient thermoreflectance (TTR) technique is employed to study the thermal conductivity of β-Ga2O3 and high Al-content AlxGa1-xN semiconductors, which are very promising materials for high-power device applications. The experimental data are analyzed with the Callaway's model taking into account all relevant phonon scattering processes. Our results show that out-of-plane thermal conductivity of high Al-content AlxGa1-xN and (−201) β-Ga2O3 is of the same order of magnitude and approximately one order lower than that of GaN or AlN. The low thermal conductivity is attributed to the dominant phonon-alloy scattering in AlxGa1-xN and to the strong Umklapp phonon-phonon scattering in β-Ga2O3. It is also found that the phonon-boundary scattering is essential in thin β-Ga2O3 and AlxGa1-xN layers even at high temperatures and the thermal conductivity strongly deviates from the common 1/T temperature dependence. DA - 2020/2/15/ PY - 2020/2/15/ DO - 10.1016/j.physb.2019.411810 VL - 579 SP - SN - 1873-2135 KW - Thermal conductivity KW - Ga2O3 KW - AlGaN ER - TY - JOUR TI - Perylene-diimide-based n-type semiconductors with enhanced air and temperature stable photoconductor and transistor properties AU - Yuen, Jonathan D. AU - Pozdin, Vladimir A. AU - Young, Ashlyn T. AU - Turner, Brendan L. AU - Giles, Ian D. AU - Naciri, Jawad AU - Trammell, Scott A. AU - Charles, Paul T. AU - Stenger, David A. AU - Daniele, Michael A. T2 - DYES AND PIGMENTS AB - We report the synthesis and characterization of highly air and temperature stable, solution-processed, n-type organic semiconductors: a perylene-diimide monomer and a perylene-diimide-based pendant polymer. When integrated into a transistor structure, both materials possess pure n-type transport with mobility as high as 10−5 cm2 V−1 s−1 for the polymer. The organic semiconductors exhibit good photoconductor properties, with photocurrent to dark current ratios of up to 103 for the monomer, despite its lower FET mobility. The differences in transistor and photoconductor properties suggest different applications for each material. Both materials can be processed in air, and their transport properties have good air stability, improving with annealing even up to 200 °C in air. It is notable that such air-stable photoconductivity and transport properties have rarely been reported for n-type organic semiconductors before, as most n-type organic semiconductors are not stable in air. Hence, these materials may have potential in a wide range of applications. DA - 2020/3// PY - 2020/3// DO - 10.1016/j.dyepig.2019.108014 VL - 174 SP - SN - 1873-3743 KW - Perylene KW - n-type KW - Photoconductor KW - Field effect transistor KW - Air stable ER - TY - JOUR TI - Magnon-drag thermopower in antiferromagnets versus ferromagnets AU - Polash, Md. Mobarak Hossain AU - Mohaddes, Farzad AU - Rasoulianboroujeni, Morteza AU - Vashaee, Daryoosh T2 - Journal of Materials Chemistry C AB - Multi magnon interaction with carriers limits the magnon lifetime in FMs compared to AFMs. The longer lifetime, double degeneracy, and higher group velocity of magnons in AFMs generally lead to higher first-order magnon-carrier drag thermopower. DA - 2020/// PY - 2020/// DO - 10.1039/C9TC06330G VL - 8 IS - 12 SP - 4049-4057 UR - https://doi.org/10.1039/C9TC06330G ER - TY - JOUR TI - Allocation of Computation-Intensive Graph Jobs Over Vehicular Clouds in IoV AU - LiWang, M. AU - Hosseinalipour, Seyyedali AU - Gao, Zhibin AU - Tang, Yuliang AU - Huang, Lianfen AU - Dai, Huaiyu T2 - IEEE INTERNET OF THINGS JOURNAL AB - Graph jobs represent a wide variety of computation-intensive tasks in which computations are represented by graphs consisting of components (denoting either data sources or data processing) and edges (corresponding to data flows between the components). Recent years have witnessed dramatic growth in smart vehicles and computation-intensive graph jobs, which pose new challenges to the provision of efficient services related to the Internet of Vehicles. Fortunately, vehicular clouds formed by a collection of vehicles, which allows jobs to be offloaded among vehicles, can substantially alleviate heavy on-board workloads and enable on-demand provisioning of computational resources. In this paper, we present a novel framework for vehicular clouds that maps components of graph jobs to service providers via opportunistic vehicle-to-vehicle communication. Then, graph job allocation over vehicular clouds is formulated as a non-linear integer programming with respect to vehicles' contact duration and available resources, aiming to minimize job completion time and data exchange cost. The problem is addressed for two scenarios: low-traffic and rush-hours. For the former, we determine the optimal solutions for the problem. In the latter case, given the intractable computations for deriving feasible allocations, we propose a novel low complexity randomized graph job allocation mechanism by considering hierarchical tree based subgraph isomorphism. We evaluate the performance of our proposed algorithms through extensive simulations. DA - 2020/1// PY - 2020/1// DO - 10.1109/JIOT.2019.2949602 VL - 7 IS - 1 SP - 311-324 SN - 2327-4662 KW - Resource management KW - Cloud computing KW - Task analysis KW - Servers KW - Computational modeling KW - Internet of Things KW - Mobile handsets KW - Computation-intensive graph jobs KW - computation offloading KW - subgraph isomorphism KW - vehicular clouds (VCs) ER - TY - JOUR TI - Early Warning of mmWave Signal Blockage and AoA Transition Using sub-6 GHz Observations AU - Ali, Ziad AU - Duel-Hallen, Alexandra AU - Hallen, Hans T2 - IEEE COMMUNICATIONS LETTERS AB - The susceptibility of millimeter-wave (mmWave) signals to physical blockage and abrupt signal strength variations presents a challenge to reliable 5G communication. This work proposes and examines the feasibility of utilizing lower-frequency signals as early-warning indicators of mobile mmWave signal blockage or recovery. A physics-based channel simulation tool incorporating Fresnel diffraction and image sources is employed to demonstrate that sub-6 GHz signals "lead" mmWave signals in reaching a specific signal-strength threshold by several to tens of milliseconds at mobile speeds, suggesting early-warning systems are viable. This predictive approach stems from frequency-dependent properties of diffraction and does not assume a specific topology or mobile and obstacle speeds. Realistic simulations that include transitions from line of sight (LoS) to non-line of sight (NLoS) and reflection scenarios are employed to verify the proposed prediction capabilities. Moreover, prediction of the strongest multipath component and its angle of arrival (AoA) using sub-6 GHz observations is investigated. DA - 2020/1// PY - 2020/1// DO - 10.1109/LCOMM.2019.2952602 VL - 24 IS - 1 SP - 207-211 SN - 1558-2558 KW - mmWave KW - blockage prediction KW - Fresnel diffraction KW - physical channel model KW - shadowing KW - hybrid communications ER - TY - JOUR TI - Power-Aware Allocation of Graph Jobs in Geo-Distributed Cloud Networks AU - Hosseinalipour, Seyyedali AU - Nayak, Anuj AU - Dai, Huaiyu T2 - IEEE TRANSACTIONS ON PARALLEL AND DISTRIBUTED SYSTEMS AB - In the era of big-data, the jobs submitted to the clouds exhibit complicated structures represented by graphs, where the nodes denote the sub-tasks each of which can be accommodated at a slot in a server, while the edges indicate the communication constraints among the sub-tasks. We develop a framework for efficient allocation of graph jobs in geo-distributed cloud networks (GDCNs), explicitly considering the power consumption of the datacenters (DCs). We address the following two challenges arising in graph job allocation: i) the allocation problem belongs to NP-hard nonlinear integer programming; ii) the allocation requires solving the NP-complete sub-graph isomorphism problem, which is particularly cumbersome in large-scale GDCNs. We develop a suite of efficient solutions for GDCNs of various scales. For small-scale GDCNs, we propose an analytical approach based on convex programming. For medium-scale GDCNs, we develop a distributed allocation algorithm exploiting the processing power of DCs in parallel. Afterward, we provide a novel low-complexity (decentralized) sub-graph extraction method, based on which we introduce cloud crawlers aiming to extract allocations of good potentials for large-scale GDCNs. Given these suggested strategies, we further investigate strategy selection under both fixed and adaptive DC pricing schemes, and propose an online learning algorithm for each. DA - 2020/4/1/ PY - 2020/4/1/ DO - 10.1109/TPDS.2019.2943457 VL - 31 IS - 4 SP - 749-765 SN - 1558-2183 KW - Resource management KW - Cloud computing KW - Power demand KW - Servers KW - Task analysis KW - Twitter KW - Distributed algorithms KW - Big-data KW - graph jobs KW - geo-distributed cloud networks KW - datacenter power consumption KW - job allocation KW - integer programming KW - convex optimization KW - online learning ER - TY - JOUR TI - Thermal Performance and Reliability Analysis of a Medium-Voltage Three-Phase Inverter Considering the Influence of High $dv/dt$ on Parasitic Filter Elements AU - Anurag, Anup AU - Acharya, Sayan AU - Bhattacharya, Subhashish AU - Weatherford, Todd R. T2 - IEEE Journal of Emerging and Selected Topics in Power Electronics AB - In recent years, the use of silicon carbide (SiC) power semiconductor devices in medium-voltage (MV) applications has been made possible due to the development of high blocking voltage (10-15 kV)-based devices. While the use of these devices brings in a lot of advantages, the semiconductor devices are exposed to high peak stress (of up to 15 kV) and a very high dv/dt (of up to 100 kV/μs). The high dv/dt across the devices leads to a high dv/dt across other components connected to the system. This makes the effect of the parasitic capacitance across the components to be of paramount importance since an additional current flows through the components and, consequently, through the switching device. This additional current flows during each switching transition and leads to increased switching losses in the device. This article analyzes the effect of these additional losses on the lifetime of the device. The thermal performance of a three-phase inverter power block is provided, and a mission profile (solar irradiance and temperature)-based analysis is carried out to account for the additional junction temperature rise. The rainflow counting method is implemented to identify the mean and amplitude of each thermal cycle. An empirical device lifetime model is used to calculate the number of cycles to failure. Finally, the Palgrem Miner rule is used to quantify the total damage in the device. Comparisons have been carried out on basis of lifetime for both the cases (with and without the influence of parasitic capacitances). This analysis can be helpful in validating the importance of the design of filter inductors in these MV applications. DA - 2020/3// PY - 2020/3// DO - 10.1109/JESTPE.2019.2952570 VL - 8 IS - 1 SP - 486-494 J2 - IEEE J. Emerg. Sel. Topics Power Electron. OP - SN - 2168-6777 2168-6785 UR - http://dx.doi.org/10.1109/jestpe.2019.2952570 DB - Crossref KW - 10-kV SiC MOSFETs KW - lifetime modeling KW - medium voltage (MV) KW - silicon carbide (SiC) KW - thermal performance ER - TY - JOUR TI - Robust Consensus-Based Distributed Energy Management for Microgrids With Packet Losses Tolerance AU - Duan, Jie AU - Chow, Mo-Yuen T2 - IEEE TRANSACTIONS ON SMART GRID AB - The well-developed consensus algorithm provides an elegant distributed way for solving the energy management problem. The convergence of the consensus-based distributed approach depends on the reliable exchange of the information with neighbors. This assumption might be violated in practice due to inevitable and random packet losses. In this paper, the impact of packet losses on the consensus-based distributed approach is analyzed. We show the iterative calculation converges to an incorrect solution in the presence of packet losses, where the power supply could not meet with the demand. More importantly, we find the error in the final result is accumulated over every packet loss event, and we identify the critical information that cause the error. Based on the analysis, a corrective method is proposed to assure convergence to the right schedule. The corrective method has two features: 1) it uses the original consensus network, and no communication reconfiguration is needed; and 2) no retransmissions for the lost packets are needed, instead, the errors are compensated by a new variable introduced in the update rule. We show that the proposed algorithm could achieve the optimal solution in the presence of packet losses. Numerical simulation results are used to validate the proposed algorithm. DA - 2020/1// PY - 2020/1// DO - 10.1109/TSG.2019.2921231 VL - 11 IS - 1 SP - 281-290 SN - 1949-3061 KW - Consensus algorithm KW - energy management KW - distributed control KW - packet losses KW - smart grid ER - TY - JOUR TI - 600 V 4H-SiC MOSFETs Fabricated in Commercial Foundry With Reduced Gate Oxide Thickness of 27 nm to Achieve IGBT-Compatible Gate Drive of 15 V (vol 40, pg 1792, 2019) AU - Agarwal, Aditi AU - Han, Kijeong AU - Jayant Baliga, B. T2 - IEEE ELECTRON DEVICE LETTERS DA - 2020/1// PY - 2020/1// DO - 10.1109/LED.2019.2956966 VL - 41 IS - 1 SP - 195-195 SN - 1558-0563 KW - MOSFET KW - Silicon carbide KW - Logic gates KW - Silicon KW - Foundries KW - Insulated gate bipolar transistors KW - Object recognition ER - TY - JOUR TI - Self-Heating Characterization of $\beta$ -Ga2O3 Thin-Channel MOSFETs by Pulsed ${I}$ - ${V}$ and Raman Nanothermography AU - Blumenschein, Nicholas A. AU - Moser, Neil A. AU - Heller, Eric R. AU - Miller, Nicholas C. AU - Green, Andrew J. AU - Popp, Andreas AU - Crespo, Antonio AU - Leedy, Kevin AU - Lindquist, Miles AU - Moule, Taylor AU - Dalcanale, Stefano AU - Mercado, Elisha AU - Singh, Manikant AU - Pomeroy, James W. AU - Kuball, Martin AU - Wagner, Gunter AU - Paskova, Tania AU - Muth, John F. AU - Chabak, Kelson D. AU - Jessen, Gregg H. T2 - IEEE TRANSACTIONS ON ELECTRON DEVICES AB - β-Ga 2 O 3 thin-channel MOSFETs were evaluated using both dc and pulsed I-V measurements. The reported pulsed I-V technique was used to study selfheating effects in the MOSFET channel. The device was analyzed over a large temperature range of 23 °C-200 °C. A relationship between dissipated power and channel temperature was established, and it was found that the MOSFET channel was heating up to 208 °C when dissipating 2.5 W/mm of power. The thermal resistance of the channel was found to be 73 °C-mm/W. The results are supported with the experimental Raman nanothermography and thermal simulations and are in reasonable agreement with pulsed I-V findings. The high thermal resistance underpins the importance of optimizing thermal management in future Ga 2 O 3 devices. DA - 2020/1// PY - 2020/1// DO - 10.1109/TED.2019.2951502 VL - 67 IS - 1 SP - 204-211 SN - 1557-9646 KW - Channel temperature KW - gallium oxide KW - MOSFET KW - pulsed I-V measurements ER - TY - JOUR TI - Optical crosstalk and off-axis modeling of an intrinsic coincident polarimeter AU - Yang, Ruonan AU - Sen, Pratik AU - Brendan T. O'Connor, AU - Kudenov, Michael W. T2 - APPLIED OPTICS AB - Polarimeters have broad applications in remote sensing, astronomy, and biomedical imaging to measure the emitted, reflected, or transmitted state of polarization. An intrinsic coincident (IC) full-Stokes polarimeter was previously demonstrated by our group, in a free space configuration, by using stain-aligned polymer-based organic photovoltaics. To minimize the model’s complexity, these were tilted to avoid crosstalk from back-reflections. We present a theoretical model of a monolithic IC polarimeter that considers the back-reflection’s influence for on-axis light. The model was validated using a monolithic four-detector polarimeter, which achieved an error of less than 3%. Additionally, an off-axis model was produced and validated for a simpler two detector polarimeter, demonstrating an error between the TM and TE polarized components of less than 3% for angles spanning an 18° incidence cone. DA - 2020/1/1/ PY - 2020/1/1/ DO - 10.1364/AO.59.000156 VL - 59 IS - 1 SP - 156-164 SN - 2155-3165 ER - TY - JOUR TI - Review of wearable thermoelectric energy harvesting: From body temperature to electronic systems AU - Nozariasbmarz, Amin AU - Collins, Henry AU - Dsouza, Kelvin AU - Polash, Mobarak Hossain AU - Hosseini, Mahshid AU - Hyland, Melissa AU - Liu, Jie AU - Malhotra, Abhishek AU - Ortiz, Francisco Matos AU - Mohaddes, Farzad AU - Ramesh, Viswanath Padmanabhan AU - Sargolzaeiaval, Yasaman AU - Snouwaert, Nicholas AU - Ozturk, Mehmet C. AU - Vashaee, Daryoosh T2 - APPLIED ENERGY AB - Global demand for battery-free metrics and health monitoring devices has urged leading research agencies and their subordinate centers to set human energy harvesting and self-powered wearable technologies as one of their primary research objectives. After an overview of wearables market trends, different active and passive methods of body energy harvesting for powering low-consumption electronic devices are introduced, and challenges of device fabrication are discussed. The discussion continues with the primary emphasis on thermoelectric generators for body heat harvesting. The physiological aspects of the human body involved in heat generation are elaborated. System requirements and the influence of different parameters on the performance of thermoelectric generators are studied at the material, device, and system levels. Finally, the advancements in the development of rigid and flexible thermoelectric generators for wearable and textile integration are presented. DA - 2020/1/15/ PY - 2020/1/15/ DO - 10.1016/j.apenergy.2019.114069 VL - 258 SP - SN - 1872-9118 UR - https://publons.com/publon/30967440/ KW - Self-powered devices KW - Body heat harvesting KW - Wearable technology KW - Thermoelectric generators KW - Flexible harvester ER - TY - JOUR TI - Performance Evaluation of a Loop Thermosyphon-Based Heatsink for High-Power SiC-Based Converter Applications AU - Acharya, Sayan AU - Anurag, Anup AU - Bhattacharya, Subhashish AU - Pellicone, Devin T2 - IEEE Transactions on Components, Packaging and Manufacturing Technology AB - Thermal management system (TMS) of a power converter directly dictates the available power rating, power density, semiconductor module reliability, and its operating lifetime. For the latest-generation wide bandgap (WBG) semiconductor device-based converters, it is challenging to extract the generated heat from the devices due to smaller die area as compared to its silicon (Si) counterparts. In this paper, the thermal performance of a new loop thermosiphon-based TMS for silicon carbide (SiC) semiconductor device-based power conversion system is presented. The working principle and design of the TMS are shown, and the performance of the designed TMS in both transient and steady-state conditions of power dissipation is evaluated. Furthermore, an accurate thermoelectrical model of the TMS is presented, and the circuit parameters are quantified by experimental results. This analysis helps to estimate the device junction temperature in real time during converter operation. Moreover, detailed simulations are carried out with the derived TMS thermal model to evaluate its performance at low fundamental frequencies at rated currents. The experimental results and the simulation studies indicate that the TMS offers a low thermal resistance and can extract a large amount of heat without increasing the device junction temperatures beyond their rated values. Furthermore, the designed TMS is able to maintain the junction temperature ripples at low fundamental frequencies within small values, which helps to increase the lifetime of the power modules significantly, as compared to conventional heatsinks. DA - 2020/1// PY - 2020/1// DO - 10.1109/TCPMT.2019.2923332 VL - 10 IS - 1 SP - 99-110 J2 - IEEE Trans. Compon., Packag. Manufact. Technol. OP - SN - 2156-3950 2156-3985 UR - http://dx.doi.org/10.1109/tcpmt.2019.2923332 DB - Crossref KW - Junctions KW - Silicon carbide KW - Reliability KW - Cooling KW - Multichip modules KW - Manufacturing KW - Continuous tests KW - loop thermosyphon KW - low-fundamental-frequency operations KW - medium voltage KW - silicon carbide devices KW - thermal management system (TMS) KW - wide bandgap (WBG) devices ER - TY - JOUR TI - Thermoelectric generators for wearable body heat harvesting: Material and device concurrent optimization AU - Nozariasbmarz, Amin AU - Suarez, Francisco AU - Dycus, J. Houston AU - Cabral, Matthew J. AU - LeBeau, James M. AU - Ozturk, Mehmet C. AU - Vashaee, Daryoosh T2 - NANO ENERGY AB - Body heat harvesting systems based on thermoelectric generators (TEGs) can play a significant role in wearable electronics intended for continuous, long-term health monitoring. However, to date, the harvested power density from the body using TEGs is limited to a few micro-watts per square centimeter, which is not sufficient to turn on many wearables. The thermoelectric materials research has been mainly focused on enhancing the single parameter zT, which is insufficient to meet the requirements for wearable applications. To develop TEGs that work effectively in wearable devices, one has to consider the material, device, and system requirements concurrently. Due to the lack of an efficient heatsink and the skin thermal resistance, a key challenge to achieving this goal is to design systems that maximize the temperature differential across the TEG while not compromising the body comfort. This requires favoring approaches that deliver the largest possible device thermal resistance relative to the external parasitic resistances. Therefore, materials with low thermal conductivity are critically important to maximize the temperature gradient. Also, to achieve a high boost converter efficiency, wearable TEGs need to have the highest possible output voltage, which calls for a high Seebeck coefficient. At the device level, dimensions of the legs (length versus the base area) and fill factor are both critical parameters to ensure that the parasitic thermal resistances are again negligible compared to the resistance of the module itself. In this study, the concurrent impact of material and device parameters on the efficiency of wearable TEGs is considered. Nanocomposite thermoelectric materials based on bismuth telluride alloys were synthesized using microwave processing and optimized to meet the requirements of wearable TEGs. Microwave energy decrystallized the material leading to a strong reduction of the thermal conductivity while maintaining a high zT at the body temperature. A comprehensive quasi-3D analytical model was developed and used to optimize the material and device parameters. The nanocomposite TEG produced 44 μW/cm2 under no air flow condition, and 156.5 μW/cm2 under airflow. In comparison to commercial TEGs tested under similar conditions, the nanocomposite based TEGs exhibited 4–7 times higher power density on the human body depending on the convective cooling conditions. DA - 2020/1// PY - 2020/1// DO - 10.1016/j.nanoen.2019.104265 VL - 67 SP - SN - 2211-3282 KW - Thermoelectric generators KW - Nanocomposites KW - Microwave radiation KW - Self-powered devices KW - Body heat harvesting KW - Wearable technology ER - TY - JOUR TI - Detection and Classification of UAVs Using RF Fingerprints in the Presence of Wi-Fi and Bluetooth Interference AU - Ezuma, Martins AU - Erden, Fatih AU - Anjinappa, Chethan Kumar AU - Ozdemir, Ozgur AU - Guvenc, Ismail T2 - IEEE OPEN JOURNAL OF THE COMMUNICATIONS SOCIETY AB - This paper investigates the problem of detection and classification of unmanned aerial vehicles (UAVs) in the presence of wireless interference signals using a passive radio frequency (RF) surveillance system. The system uses a multistage detector to distinguish signals transmitted by a UAV controller from the background noise and interference signals. First, RF signals from any source are detected using a Markov models-based naïve Bayes decision mechanism. When the receiver operates at a signal-to-noise ratio (SNR) of 10 dB, and the threshold, which defines the states of the models, is set at a level 3.5 times the standard deviation of the preprocessed noise data, a detection accuracy of 99.8% with a false alarm rate of 2.8% is achieved. Second, signals from Wi-Fi and Bluetooth emitters, if present, are detected based on the bandwidth and modulation features of the detected RF signal. Once the input signal is identified as a UAV controller signal, it is classified using machine learning (ML) techniques. Fifteen statistical features extracted from the energy transients of the UAV controller signals are fed to neighborhood component analysis (NCA), and the three most significant features are selected. The performance of the NCA and five different ML classifiers are studied for 15 different types of UAV controllers. A classification accuracy of 98.13% is achieved by k-nearest neighbor classifier at 25 dB SNR. Classification performance is also investigated at different SNR levels and for a set of 17 UAV controllers which includes two pairs from the same UAV controller models. DA - 2020/// PY - 2020/// DO - 10.1109/OJCOMS.2019.2955889 VL - 1 SP - 60-76 SN - 2644-125X UR - https://doi.org/10.1109/OJCOMS.2019.2955889 KW - Interference KW - machine learning KW - Markov models KW - RF fingerprinting KW - unmanned aerial vehicles (UAVs) KW - UAV detection and classification ER - TY - JOUR TI - Measurement-driven optimal control of utility-scale power systems: A New York State grid perspective AU - Mukherjee, Sayak AU - Babaei, Saman AU - Chakrabortty, Aranya AU - Fardanesh, Bruce T2 - INTERNATIONAL JOURNAL OF ELECTRICAL POWER & ENERGY SYSTEMS AB - This paper focuses on designing and testing a supplementary controller for an ultra-large, utility-scale power system, namely the New York State (NYS) Power Grid from a completely measurement-based perspective. We present the control design using the Flexible AC Transmission System (FACTS) facility at the NYS grid. We use the utility-scale Eastern Interconnection (EI) model consisting of over 70,000 buses in the PSS/E platform for this research. The coherency structure of the NYS grid is analyzed by performing Principal Component Analysis (PCA) on frequency measurements obtained from multiple contingency simulations. Thereafter, we use the frequency measurements from PMU-enabled buses to identify a reduced-order state space model of the grid such that it matches the input-output characteristics along with identifying the inter-area modes. This model is then used to design the Linear Quadratic Gaussian (LQG) based optimal FACTS controller. Then the controller is implemented in the PSS/E model of the Eastern Interconnection (EI) as a PSS/E-FORTRAN based user defined module. The effectiveness of the control performance is shown using the non-linear simulations under different contingencies provided by the New York Independent System Operator (NYISO). DA - 2020/2// PY - 2020/2// DO - 10.1016/j.ijepes.2019.105470 VL - 115 SP - SN - 1879-3517 KW - Inter-area oscillations KW - Wide-Area Damping Controller (WADC) KW - Measurement based LQG KW - FACTS KW - Damping control for an utility-scale power system ER - TY - JOUR TI - Nanomaterial-Enabled Flexible and Stretchable Sensing Systems: Processing, Integration, and Applications AU - Yao, Shanshan AU - Ren, Ping AU - Song, Runqiao AU - Liu, Yuxuan AU - Huang, Qijin AU - Dong, Jingyan AU - Brendan T. O'Connor, AU - Zhu, Yong T2 - ADVANCED MATERIALS AB - Abstract Nanomaterial‐enabled flexible and stretchable electronics have seen tremendous progress in recent years, evolving from single sensors to integrated sensing systems. Compared with nanomaterial‐enabled sensors with a single function, integration of multiple sensors is conducive to comprehensive monitoring of personal health and environment, intelligent human–machine interfaces, and realistic imitation of human skin in robotics and prosthetics. Integration of sensors with other functional components promotes real‐world applications of the sensing systems. Here, an overview of the design and integration strategies and manufacturing techniques for such sensing systems is given. Then, representative nanomaterial‐enabled flexible and stretchable sensing systems are presented. Following that, representative applications in personal health, fitness tracking, electronic skins, artificial nervous systems, and human–machine interactions are provided. To conclude, perspectives on the challenges and opportunities in this burgeoning field are considered. DA - 2020/4// PY - 2020/4// DO - 10.1002/adma.201902343 VL - 32 IS - 15 SP - SN - 1521-4095 KW - electronic skins KW - flexible and stretchable systems KW - flexible hybrid electronics KW - health and fitness tracking KW - human-machine interfaces ER -