Conclusion: The results highlight the potential of this novel anisotropic imaging in clinical applications because the conditions of musculoskeletal fiber orientation can be easily and accurately evaluated in real time by DDSWI.
DA - 2022/9//
PY - 2022/9//
DO - 10.1109/TBME.2022.3152896
VL - 69
IS - 9
SP - 2745-2754
SN - 1558-2531
KW - Muscles
KW - Imaging
KW - Transducers
KW - Elasticity
KW - Biomedical measurement
KW - Anisotropic magnetoresistance
KW - Elastography
KW - Muscle anisotropy
KW - skeletal muscle
KW - shear wave elasticity imaging (SWEI)
KW - tissue elasticity
KW - tissue isotropy
ER -
TY - JOUR
TI - Resembled Tactile Feedback for Object Recognition Using a Prosthetic Hand
AU - Vargas, Luis
AU - Huang, He
AU - Zhu, Yong
AU - Kamper, Derek
AU - Hu, Xiaogang
T2 - IEEE ROBOTICS AND AUTOMATION LETTERS
AB - Tactile feedback in the hand is essential for interaction with objects. Here, we evaluated how artificial tactile sensation affected the recognition of object properties using a myoelectrically controlled prosthetic hand. Electromyogram signals from the flexor and extensor finger muscles were used to continuously control either prosthetic joint velocity or position. Participants grasped objects of varying shape or size using the prosthetic hand. Tactile feedback was evoked by transcutaneous nerve stimulation along the participant's upper arm and modulated based on the prosthetic-object contact force. Multi-channel electrical stimulation targeted the median and ulnar nerve bundles to produce resembled tactile sensations at distinct hand regions. The results showed that participants could gauge the onset timing of tactile feedback to discern object shape and size. We also found that the position-controller led to a greater recognition accuracy of object size compared with velocity-control, potentially due to supplemental joint position information from muscle activation level. Our findings demonstrate that non-invasive tactile feedback can enable effective object shape and size recognition during prosthetic control. The evaluation of tactile feedback across myoelectric controllers can help understand the interplay between sensory and motor pathways involved in the control of assistive devices.
DA - 2022/10//
PY - 2022/10//
DO - 10.1109/LRA.2022.3196958
VL - 7
IS - 4
SP - 10977-10984
SN - 2377-3766
KW - Tactile feedback
KW - prosthetic control
KW - object recognition
KW - transcutaneous nerve stimulation
ER -
TY - JOUR
TI - A Permanent Magnet Synchronous Spherical Motor for High-Mobility Servo-Actuation
AU - Shah, Jay A.
AU - Miller, Samuel R.
AU - Jernigan, Shaphan R.
AU - Buckner, Gregory D.
T2 - MACHINES
AB - The development of direct-drive spherical motors offers a potential solution to the limitations of conventional multiple degree-of-freedom (DOF) actuators, which typically utilize single-DOF joints (rotational and/or prismatic), arranged in series or parallel and powered by multiple single-DOF actuators. These configurations can be accompanied by kinematic singularities, backlash, limited power density and efficiency, and computationally expensive inverse kinematics. This paper details the design, fabrication and experimental testing of permanent magnet synchronous spherical motors (PMSSM) for multi-DOF servo-actuation. Its stator-pole arrangement is based on a Goldberg polyhedron, with each pole comprised of hexagonal or pentagonal inner and outer plates. The stator geometry and winding configurations are optimized using electromagnetic finite element analysis. A custom-made controller board includes a microcontroller, servo drivers, a wireless serial interface, and a USB PC interface. Angular orientation is sensed using an inertial measurement unit in wireless communication with the microcontroller. A PID controller is implemented and demonstrated for time-varying reference trajectories.
DA - 2022/8//
PY - 2022/8//
DO - 10.3390/machines10080612
VL - 10
IS - 8
SP -
SN - 2075-1702
KW - spherical motor
KW - permanent magnet synchronous motor
KW - PID control
ER -
TY - CONF
TI - Detaching Water Droplets from a Fiber using a Magnetic Field
AU - Farhan, M.
AU - Tafreshi, H.V.
T2 - 13th World Filtration Congress
C2 - 2022/10/5/
C3 - 13th World Filtration Congress
CY - San Diego, CA
DA - 2022/10/5/
PY - 2022/10/5/
ER -
TY - CONF
TI - Adhesion Forces on A Droplet Sandwiched between Hydrophobic Fibrous Layers
AU - Moghadam, A.
AU - Tafreshi, H.V.
T2 - 13th World Filtration Congress
C2 - 2022/10/5/
C3 - 13th World Filtration Congress
CY - San Diego, CA
DA - 2022/10/5/
PY - 2022/10/5/
ER -
TY - CONF
TI - Studying Filtration through Micro- And Macro-Scale Modeling and Experiment
AU - Tafreshi, H.V.
T2 - 13th World Filtration Congress
C2 - 2022/10/5/
C3 - 13th World Filtration Congress
CY - San Diego, CA
DA - 2022/10/5/
PY - 2022/10/5/
ER -
TY - JOUR
TI - Laser Powder Bed Fusion of ODS 14YWT from Gas Atomization Reaction Synthesis Precursor Powders
AU - Saptarshi, Sourabh
AU - DeJong, Matthew
AU - Rock, Christopher
AU - Anderson, Iver
AU - Napolitano, Ralph
AU - Forrester, Jennifer
AU - Lapidus, Saul
AU - Kaoumi, Djamel
AU - Horn, Timothy
T2 - JOM
AB - Abstract Laser powder bed fusion (LPBF) additive manufacturing (AM) is a promising route for the fabrication of oxide dispersion strengthened (ODS) steels. In this study, 14YWT ferritic steel powders were produced by gas atomization reaction synthesis (GARS). The rapid solidification resulted in the formation of stable, Y-containing intermetallic Y 2 Fe 17 on the interior of the powder and a stable Cr-rich oxide surface. The GARS powders were consolidated with LPBF. Process parameter maps identified a stable process window resulting in a relative density of 99.8%. Transmission electron microscopy and high-energy x-ray diffraction demonstrated that during LPBF, the stable phases in the powder dissociated in the liquid melt pool and reacted to form a high density (1.7 × 10 20 /m 3 ) of homogeneously distributed Ti 2 Y 2 O 7 pyrochlore dispersoids ranging from 17 to 57 nm. The use of GARS powder bypasses the mechanical alloying step typically required to produce ODS feedstock. Preliminary mechanical tests demonstrated an ultimate tensile and yield strength of 474 MPa and 312 MPa, respectively.
DA - 2022/8/2/
PY - 2022/8/2/
DO - 10.1007/s11837-022-05418-6
VL - 8
SP -
SN - 1543-1851
ER -
TY - JOUR
TI - New insight into the flexural rigidity of multi-filament yarn
AU - Luan, Kun
AU - Kirkwood, Elizabeth
AU - Newman, Zoe
AU - West, Andre
AU - DenHartog, Emiel
T2 - TEXTILE RESEARCH JOURNAL
AB - Filament yarn is one of the most widely used soft strands in the textile industry; it exhibits excellent flexibility and is capable of being used in various productions, including knitting, weaving, braiding, sewing, and embroidery. The inherent complex interlacement between fibers, including twist, entanglement, and yarn geometry, often exhibits a nonlinear response to external loads. In addition, the interlacement of fibers also introduces difficulties when accurately measuring the flexural property of multi-filament yarn. In particular, the flexural rigidity of the yarn strongly influences the quality of end products when incorporated into novel textile technologies. In this paper, we developed a three-point bending instrument and a method for measuring the flexural rigidity of filament yarn. A representative point obeyed from Coplan’s construction on the bending constitutive curve was determined to obtain pure flexural rigidity. Furthermore, the bending process and deformations across cross-sections of filament yarns were discussed. The research provides new physical insights into the yarn bending property with the consideration of eliminating the sub-deformation variabilities. The work also paves the way for the accurate and quick measurement of the flexural rigidity of high length-to-width ratio soft materials by a three-point bending method.
DA - 2022/8/1/
PY - 2022/8/1/
DO - 10.1177/00405175221114655
VL - 8
SP -
SN - 1746-7748
KW - Three-point bending
KW - pretension
KW - spun yarn
KW - conductive yarn
KW - flexural rigidity
KW - knittability
ER -
TY - JOUR
TI - Experimental Investigation of Boundary Condition Effects in Bipennate Fluidic Artificial Muscle Bundles
AU - Hart, Rebecca
AU - Duan, Emily
AU - Bryant, Matthew
T2 - BIOINSPIRATION, BIOMIMETICS, AND BIOREPLICATION XII
AB - In this study, the implementation and performance of bipennate topology fluidic artificial muscle (FAM) bundles operating under varying boundary conditions is investigated and quantified experimentally. Soft actuators are of great interest to design engineers due to their inherent flexibility and potential to improve safety in human robot interactions. McKibben fluidic artificial muscles are soft actuators which exhibit high force to weight ratios and dynamically replicate natural muscle movement. These features, in addition to their low fabrication cost, set McKibben FAMs apart as attractive components for an actuation system. Previous studies have shown that there are significant advantages in force and contraction outputs when using bipennate topology FAM bundles as compared to the conventional parallel topology1 . In this study, we will experimentally explore the effects of two possible boundary conditions imposed on FAMs within a bipennate topology. One boundary condition is to pin the muscle fiber ends with fixed pin spacings while the other is biologically inspired and constrains the muscle fibers to remain in contact. This paper will outline design considerations for building a test platform for bipennate fluidic artificial muscle bundles with varying boundary conditions and present experimental results quantifying muscle displacement and force output. These metrics are used to analyze the tradespace between the two boundary conditions and the effect of varying pennation angles.
DA - 2022///
PY - 2022///
DO - 10.1117/12.2615896
VL - 12041
SP -
SN - 1996-756X
KW - pennate topology
KW - soft actuators
KW - fluidic artificial muscles
KW - muscle topology
KW - bioinspired
ER -
TY - JOUR
TI - Control of a dynamic load emulator for hardware-in-the-loop testing of fluidic artificial muscle bundles
AU - Mazzoleni, Nicholas
AU - Kim, Jeong Yong
AU - Bryant, Matthew
T2 - BIOINSPIRATION, BIOMIMETICS, AND BIOREPLICATION XII
AB - Fluidic artificial muscles (FAMs) have emerged as a viable and popular robotic actuation technique due to their low cost, compliant nature, and high force-to-weight-ratio. In recent years, the concept of variable recruitment has emerged as a way to improve the efficiency of conventional hydraulic robotic systems. In variable recruitment, groups of FAMs are bundled together and divided into individual motor units. Each motor unit can be activated independently, which is similar to the sequential activation pattern observed in mammalian muscle. Previous researchers have performed quasistatic characterizations of variable recruitment bundles and some simple dynamic analyses and experiments with a simple 1- DOF robot arm. We have developed a linear hydraulic characterization testing platform that will allow for the testing of different types of variable recruitment bundle configurations under different loading conditions. The platform consists of a hydraulic drive cylinder that acts as a cyber-physical hardware-in-the-loop dynamic loading emulator and interfaces with the variable recruitment bundle. The desired inertial, damping and stiffness properties of the emulator can be prescribed and achieved through an admittance controller. In this paper, we test the ability of this admittance controller to emulate different inertial, stiffness, and damping properties in simulation and demonstrate that it can be used in hardware through a proof-of-concept experiment. The primary goal of this work is to develop a unique testing setup that will allow for the testing of different FAM configurations, controllers, or subsystems and their responses to different dynamic loads before they are implemented on more complex robotic systems.
DA - 2022///
PY - 2022///
DO - 10.1117/12.2612920
VL - 12041
SP -
SN - 1996-756X
KW - Fluidic artificial muscles
KW - hardware-in-the-loop
KW - load emulator
KW - cyber-physical system
KW - bioinspired robotics
ER -
TY - JOUR
TI - Soft wearable sensors for monitoring symptoms of COVID-19 and other respiratory diseases: a review
AU - Liu, Yuxuan
AU - Shukla, Darpan
AU - Newman, Holly
AU - Zhu, Yong
T2 - PROGRESS IN BIOMEDICAL ENGINEERING
AB - The COVID-19 pandemic has put extraordinary stress on medical systems and global society more broadly. The condition of infected patients may deteriorate rapidly due to overburdened hospital systems. This raises an urgent need for real-time and remote monitoring of physiological parameters to address the challenges associated with the COVID-19 pandemic. This review will present recent progress on soft wearable sensors that can potentially be used for monitoring respiratory diseases such as COVID-19. First, emerging monitoring devices and systems that can monitor key physiological parameters as suggested by the Centers for Disease Control and Prevention (e.g. body temperature, respiration rate, heart rate, oxygen saturation and body movement) are reviewed. Then, multimodal sensor systems consisting of two or more correlative sensors are presented. This review will conclude with challenges and future directions for wearable sensors for the diagnosis and therapy of respiratory diseases. While this review focuses on COVID-19, the sensing technologies reviewed can be applicable to other respiratory diseases such as H1N1 influenza.
DA - 2022/1//
PY - 2022/1//
DO - 10.1088/2516-1091/ac2eae
VL - 4
IS - 1
SP -
SN - 2516-1091
KW - respiratory diseases
KW - wearable sensors
KW - soft sensors
KW - COVID-19
KW - health monitoring
ER -
TY - JOUR
TI - Enhanced piezoelectric and dielectric properties of AC poled sliver-mode Pb(In1/2Nb1/2)O-3-Pb(Mg1/3Nb2/3)O-3-PbTiO3 single crystals for ultrasonic abdomen probes
AU - Sun, Yiqin
AU - Ota, Yuhei
AU - Kim, Hwang-Pill
AU - Fujii, Tadashi
AU - Yamashita, Yohachi
AU - Karaki, Tomoaki
AU - Jiang, Xiaoning
AU - Wang, Zhuangkai
T2 - JAPANESE JOURNAL OF APPLIED PHYSICS
AB - Abstract The effect of AC poling (ACP) on the piezoelectric and dielectric properties of diced sliver-mode vibrators (L13 × W0.15–0.30 × T0.51 mm 3 ) was investigated for a convex abdomen ultrasound (US) probe that is made of a large Pb(In 1/2 Nb 1/2 )O 3 -Pb(Mg 1/3 Nb 2/3 )O 3 −0.3PbTiO 3 (PIN-PMN-PT) single crystal (SC) plate (L13 × W60 × T0.51 mm 3 ). The SC was manufactured by the continuous feeding Bridgman (CF-BM) method. The ε 33 T / ε 0 aging rate (AR) of both DCP and ACP large plate SCs were found to be within 1%/decade suggesting no obvious property degradation. After array dicing, a considerable decrease in electromechanical and dielectric properties was observed. After a post-dicing DCP, the diced DCP-DCP 0.15 mm wide SC slivers showed ε 33 T / ε 0 and electromechanical coupling factor ( k ′ 33 ) of 4300 and 89.1%, respectively. The diced ACP-DCP 0.15 mm wide SC slivers showed improved ε 33 T / ε 0 and k ′ 33 of 5980 and 92.2%, respectively, which are considered useful in practical medical array transducer applications.
DA - 2022/11/1/
PY - 2022/11/1/
DO - 10.35848/1347-4065/ac8142
VL - 61
IS - SN
SP -
SN - 1347-4065
ER -
TY - JOUR
TI - New International Guidelines and Consensus on the Use of Lung Ultrasound
AU - Demi, Libertario
AU - Wolfram, Frank
AU - Klersy, Catherine
AU - De Silvestri, Annalisa
AU - Ferretti, Virginia Valeria
AU - Muller, Marie
AU - Miller, Douglas
AU - Feletti, Francesco
AU - Welnicki, Marcin
AU - Buda, Natalia
AU - Skoczylas, Agnieszka
AU - Pomiecko, Andrzej
AU - Damjanovic, Domagoj
AU - Olszewski, Robert
AU - Kirkpatrick, Andrew W.
AU - Breitkreutz, Raoul
AU - Mathis, Gebhart
AU - Soldati, Gino
AU - Smargiassi, Andrea
AU - Inchingolo, Riccardo
AU - Perrone, Tiziano
T2 - JOURNAL OF ULTRASOUND IN MEDICINE
AB - Following the innovations and new discoveries of the last 10 years in the field of lung ultrasound (LUS), a multidisciplinary panel of international LUS experts from six countries and from different fields (clinical and technical) reviewed and updated the original international consensus for point-of-care LUS, dated 2012. As a result, a total of 20 statements have been produced. Each statement is complemented by guidelines and future developments proposals. The statements are furthermore classified based on their nature as technical (5), clinical (11), educational (3), and safety (1) statements.
DA - 2022/8/22/
PY - 2022/8/22/
DO - 10.1002/jum.16088
SP -
SN - 1550-9613
KW - A-lines
KW - artificial intelligence
KW - B-lines
KW - COVID-19
KW - lung ultrasound
KW - lung ultrasound protocols
KW - lung ultrasound standardization
KW - LUS safety assurance
KW - point of care ultrasound
KW - post-COVID-19
KW - quantitative ultrasound
KW - SARS-CoV-2
KW - sonographic interstitial syndrome
KW - vertical artifacts
ER -
TY - JOUR
TI - Response of a plate with piezoelectric elements to turbulent pressure fluctuation in supersonic flow
AU - Freydin, Maxim
AU - Dowell, Earl H.
AU - Varigonda, Santosh Vaibhav
AU - Narayanaswamy, Venkateswaran
T2 - JOURNAL OF FLUIDS AND STRUCTURES
AB - The aeroelastic response of a plate with supersonic freestream flow on one side and a shallow cavity on the other to turbulent pressure fluctuations is investigated computationally and experimentally. An empirical model is developed for the pressure fluctuations in a turbulent boundary layer that accounts for spatial and spectral variations in the pressure field. Supersonic wind tunnel tests were conducted in a Mach 2.5 flow with and without an impinging shock at the plate surface. In both cases the boundary layer was turbulent. The impinging shock creates shock-wave boundary-layer interaction, which alters the characteristics of the pressure fluctuations. Pressure-sensitive paint was used to measure the unsteady pressure on the surface of a rigid plate and characterize the pressure field (local mean, rms, and the spatial coherence length) and piezoelectric patches were used as sensors to measure the response of an elastic plate. The extracted pressure parameters were used to simulate the fluid–structure response and correlate with experiments. The computed pressure perturbation due to plate motion is found to be small relative to the natural pressure fluctuation for the fluid/structural configuration studied. Computed and measured power spectra of the piezoelectric element voltage show good agreement over a wide range of structural natural frequencies. Aeroelastic response sensitivity to pressure fluctuation coherence length was also investigated computationally. It is found that with small fluid elements, which represent small-scale uncorrelated noise, the structural response is relatively small because the excitation is filtered by the plate dynamics. Experimental results suggest that the effective excitation spatial scale is on the order of the boundary layer thickness.
DA - 2022/10//
PY - 2022/10//
DO - 10.1016/j.jfluidstructs.2022.103696
VL - 114
SP -
SN - 1095-8622
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85135818767&partnerID=MN8TOARS
KW - Supersonic
KW - Fluctuating pressure
KW - Pressure sensitive paint
KW - Plate
KW - Piezoelectric materials
ER -
TY - JOUR
TI - Template‐Free Scalable Fabrication of Linearly Periodic Microstructures by Controlling Ribbing Defects Phenomenon in Forward Roll Coating for Multifunctional Applications
AU - Islam, Md Didarul
AU - Perera, Himendra
AU - Black, Benjamin
AU - Phillips, Matthew
AU - Chen, Muh‐Jang
AU - Hodges, Greyson
AU - Jackman, Allyce
AU - Liu, Yuxuan
AU - Kim, Chang‐Jin
AU - Zikry, Mohammed
AU - Khan, Saad
AU - Zhu, Yong
AU - Pankow, Mark
AU - Ryu, Jong Eun
T2 - Advanced Materials Interfaces
AB - Abstract Periodic micro/nanoscale structures from nature have inspired the scientific community to adopt surface design for various applications, including superhydrophobic drag reduction. One primary concern of practical applications of such periodic microstructures remains the scalability of conventional microfabrication technologies. This study demonstrates a simple template‐free scalable manufacturing technique to fabricate periodic microstructures by controlling the ribbing defects in the forward roll coating. Viscoelastic composite coating materials are designed for roll‐coating using carbon nanotubes (CNT) and polydimethylsiloxane (PDMS), which helps achieve a controllable ribbing with a periodicity of 114–700 µm. Depending on the process parameters, the patterned microstructures transition from the linear alignment to a random structure. The periodic microstructure enables hydrophobicity as the water contact angles of the samples ranged from 128° to 158°. When towed in a static water pool, a model boat coated with the microstructure film shows 7%–8% faster speed than the boat with a flat PDMS film. The CNT addition shows both mechanical and electrical properties improvement. In a mechanical scratch test, the cohesive failure of the CNT‐PDMS film occurs in ≈90% higher force than bare PDMS. Moreover, the nonconductive bare PDMS shows sheet resistance of 747.84–22.66 Ω □ −1 with 0.5 to 2.5 wt% CNT inclusion.
DA - 2022/8/26/
PY - 2022/8/26/
DO - 10.1002/admi.202201237
VL - 9
IS - 27
SP - 2201237
J2 - Adv Materials Inter
LA - en
OP -
SN - 2196-7350 2196-7350
UR - http://dx.doi.org/10.1002/admi.202201237
DB - Crossref
KW - multifunctional surfaces
KW - periodic microtrenches
KW - ribbing instabilities
KW - roll coating
KW - scalable manufacturing
ER -
TY - JOUR
TI - Temperature reconstruction of an axisymmetric enclosed reactive flow using simultaneous background oriented schlieren and infrared thermography
AU - Wahls, Benjamin H.
AU - Ekkad, Srinath V
T2 - MEASUREMENT SCIENCE AND TECHNOLOGY
AB - Abstract The temperature distribution of a premixed methane air flame running at a Reynolds number of 1300 on a circular burner, 12.7 mm diameter, enclosed in a fused silica cylindrical liner has been experimentally reconstructed using a non-invasive approach combining background oriented schlieren (BOS) and infrared (IR) thermography. BOS is used to characterize both the air ambient to the system, using an existing technique called 3D ray tracing, and the reactive flow inside the enclosure, with a novel modified version of 3D ray tracing. IR thermography is used to characterize the thermal/optical characteristics of the quartz glass enclosure itself, since the information is required as BOS is a line of sight imaging technique. Out of necessity, an approximated species independent relationship is used to calculate flow temperature from refractive index. A simulation is used to show this error is in the range of 5.8%–7%. Additionally, it is found that drastically simplifying the approach by removing the IR thermography system entirely and using the near outer wall air temperature from BOS/3D ray tracing to characterize the internal temperature of the quartz liner itself only causes a 1.5%–3.8% degradation in the accuracy of the reconstructed temperature field. The technique as presented is a relatively inexpensive, experimentally simple approach capable of determining the steady state temperature characteristics of optically accessible axisymmetric reactive flows.
DA - 2022/11/1/
PY - 2022/11/1/
DO - 10.1088/1361-6501/ac83e2
VL - 33
IS - 11
SP -
SN - 1361-6501
KW - background oriented schlieren
KW - infrared thermography
KW - noninvasive
KW - temperature
KW - measurement
KW - enclosed
KW - reactive flow
ER -
TY - JOUR
TI - Coupled electromagnetic and mechanical modeling and detection of buried objects
AU - Elbadry, Mohamed
AU - Wetherington, J.
AU - Zikry, M.A.
T2 - Applications in Engineering Science
AB - A time domain finite element (FE) framework was used to investigate the coupled electromagnetic (EM) and mechanical behavior of buried target systems. The coupling of the EM and mechanical fields is through using the Lorentz Force as the body force in the mechanical Cauchy equation of motion. The coupling is sequential where the EM fields and Lorentz force are first solved for, then they are used as inputs for the Cauchy equations of motion. Predictions were obtained for different loading conditions and the Method of Morris sensitivity analysis was used to understand how different mechanical and EM variables affect the buried target system. These predictions indicate that target permeability and depth had the most significant and dominant effects on the behavior of the buried target system.
DA - 2022/6//
PY - 2022/6//
DO - 10.1016/j.apples.2022.100106
VL - 10
UR - https://doi.org/10.1016/j.apples.2022.100106
ER -
TY - CONF
TI - Pressure and Strain Measurement on a 10° Control Surface of a Slender Cone in Hypersonic Flow
AU - Hedge, A.
AU - MacIntyre, Z.
AU - Hubner, J.P.
AU - Chen, M.
AU - Pandey, A.
AU - Flood, J.T.
AU - Casper, K.M.
T2 - AIAA AVIATION 2022 Forum
AB - This paper presents the results of an experimental technique to acquire full-field pressure and strain fields on the windward side of a 10° flap attached to a slender cone-slice model. Tests were conducted in the Hypersonic Wind Tunnel (M = 5, Re= 9 – 14×〖10〗^6/m, air) at Sandia National Laboratories. The flap was coated with a fast-response, pressure-sensitive paint sprayed over a photoelastic coating and located near the trailing-edge of an axial slice along the 7° slender cone. This experiment was part of a sponsored project to develop the two-coating luminescent measurement technique and apply to high-speed, fluid-structure interaction environments. Results using a low-speed micropolarizer camera with four polarization orientations show that the technique is sensitive to pressure and strain, measuring an increasing pressure and decreasing strain from leading- to trailing-edge over the surface of the flap. At the low Re condition, the pressure signal captures the separated region near the flap leading edge and compares well with schlieren and oil-film measurements, the latter on a 10° wedge. Aerodynamic heating during the run does affect the pressure signal, likely resulting in an overestimation of pressure. Results using a conventional high-speed camera with a single linear polarizer captures the first bending and torsional modes of vibration when the flap is excited by transient shutdown conditions; however, coupling is difficult to detect in the pressure response due to baseline noise and the slower temporal response of the pressure coating.
C2 - 2022/6//
C3 - AIAA AVIATION 2022 Forum
CY - Chicago, IL
DA - 2022/6//
PY - 2022/6/27/
DO - 10.2514/6.2022-4043
ER -
TY - CONF
TI - Investigation of Fountain Effect in Dual-Rotor/Wing Interaction at Low Reynolds Number
AU - Chen, M.
AU - Shen, J.
AU - Hubner, J.P.
T2 - AIAA AVIATION 2022 Forum
AB - This paper conducts a parametric investigation on whether the fountain effect in dual rotor/wing interaction exists at low disk loading and Reynolds number (disk loading < 100 N/m^2 and Reynolds number < 100,000). A commercial computational fluid dynamics package specifically developed for rotorcraft studies, RotCFD, in which the rotor is modeled as a distribution of momentum sources, was used. Numerical results are compared to an experimental study including force measurements and surface pressure measurements. The comparisons are employed to assess the accuracy of RotCFD results and help evaluate the formation of the fountain effect and its effect on rotor thrust and download force on the wing.
C2 - 2022/6//
C3 - AIAA AVIATION 2022 Forum
CY - Chicago, IL
DA - 2022/6//
PY - 2022/6/27/
DO - 10.2514/6.2022-3816
ER -
TY - JOUR
TI - Variable-Gain Sliding Mode Control for Quadrotor Vehicles: Lyapunov-based Analysis and Finite-Time Stability
AU - Miranda-Colorado, R.
AU - Dominguez-Silva, I.
AU - Aguilar, L.T.
T2 - IEEE Transactions on Control Systems Technology
DA - 2022///
PY - 2022///
ER -
TY - CONF
TI - Design and Experimental Validation of a High Power Actuator for Knee Prosthesis with Low Gear Ratio Transmission
AU - Dominguez-Silva, I.
C2 - 2022///
C3 - IEEE/ASME Transactions on Mechatronics with The 2022 IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM 2022
DA - 2022///
ER -
TY - RPRT
TI - Non-Nuclear Exploration of the Solar System
Study
AU - Brophy, John
AU - Pellegrino, Sergio
AU - Lubin, Philip
AU - Alkalai, Leon
AU - Atwater, Harry
AU - Biswas, Abi
AU - Boca, Andreea
AU - Carr, Greg
AU - Davoyan, Artur
AU - Frazier, William
AU - Gdoutos, Terry
AU - Grandidier, Jonathan
AU - Hogstrom, Kristina
AU - Hughes, Mike
AU - Johnson, Les
AU - Kelzenberg, Michael
AU - Lee, Andrew
AU - Luther, Joseph
AU - Marshall, Michael
AU - Marrese-Reading, Colleen
AU - McCarty, Steve
AU - McNutt, Ralph
AU - Petro, Elaine
AU - Polk, James
AU - Scully, Jennifer
AU - Sekerak, Michael
AU - Sellers, Ian
A3 - California Institute of Technology
DA - 2022///
PY - 2022///
DO - 10.7907/H62P-6328
PB - California Institute of Technology
UR - https://resolver.caltech.edu/CaltechAUTHORS:20220503-222804071
ER -
TY - CONF
TI - Bistable Deployable Composite Booms With Parabolic Cross-Sections
AU - Lee, Andrew J.
AU - Fernandez, Juan M.
AU - Daye, Jacob G.
AB - This paper investigates how stable equilibrium states in the extended and coiled configurations can be predicted in thin-shelled composite booms with parabolic cross-sections. These conic shapes potentially offer greater stiffness properties when compared to circular cross-sections, which is critical for improving the load bearing performance of deployed booms. Inducing bistability through the choice of composite shell layups in parabolic booms would allow for controllable self-deployment due to a less energetic coiled state when compared to monostable booms. An inextensional analytical model is used to predict the stable coiled diameters of tape spring and Collapsible Tubular Mast (CTM) booms with parabolic cross-sections. The parabolic section is discretized into circular segments using biarc spline interpolation, which allows them to be integrated into the strain energy minimization procedure used to obtain the equilibrium states. When the parabolic booms are parametrically compared against circular booms with identical layups, flattened height, and mass, the former are found to generally have better stiffness performance while being less efficient in stowed volume as evidenced by larger coiled diameters. Analytical coiled diameters and their strain energy are verified with finite element simulations for optimal parabolic tape spring and CTM booms.
C2 - 2022/1/3/
C3 - AIAA Scitech 2022 Forum
DA - 2022/1/3/
DO - 10.2514/6.2022-2264
PB - American Institute of Aeronautics and Astronautics
UR - http://dx.doi.org/10.2514/6.2022-2264
ER -
TY - JOUR
TI - Mass efficiency of strip-based coilable space structures
AU - Lee, Andrew J.
AU - Pellegrino, Sergio
T2 - INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES
AB - This paper presents a general semi-analytical study of the mass efficiency of coilable plate-like space structures. A bending architecture based on four diagonal booms that support parallel strips is compared to a cable-stayed architecture in which vertical booms and cable stays support the diagonal booms at the tip. Limiting conditions of global buckling, local buckling, material failure, and excessive deflection define the design space for each architecture. Considering pressure loads spanning several orders of magnitude, the optimal areal density of structures of size varying from a few meters to hundreds of meters is determined for both architectures. Design charts for optimal designs are provided for a range of sizes, loads, and deflection limits. It is shown that the cable-stayed architecture is always lighter than the bending architecture, from a few percent to over 30%.
DA - 2022/11/1/
PY - 2022/11/1/
DO - 10.1016/j.ijsolstr.2022.111867
VL - 254
SP -
SN - 1879-2146
UR - http://dx.doi.org/10.1016/j.ijsolstr.2022.111867
KW - Space structures
KW - Structural design
KW - Mass efficiency
KW - Areal density
KW - Deployable
KW - Cable-stayed
ER -
TY - JOUR
TI - Particle Swarm Optimization Algorithm for Guided Waves Based Damage Localization Using Fiber Bragg Grating Sensors in Remote Configuration
AU - Soman, Rohan
AU - Boyer, Alex
AU - Kim, Jee Myung
AU - Peters, Kara
T2 - SENSORS
AB - Structural health monitoring (SHM) systems may allow a reduction in maintenance costs and extend the lifetime of the structure. As a result, they are of interest to the research community. Ideally, the SHM methods should be low cost, while being able to detect and localize small levels of damage reliably and accurately. The fiber Bragg grating (FBG) sensors are light in weight, insensitive to electric and magnetic fields, and can be embedded. The edge filtering configuration for transduction allows the use of FBG for guided wave (GW) sensing. This sensitivity may be further enhanced through their application in the remote bonded configuration. This paper provides a proof-of-concept for the use of remotely bonded FBG for damage localization. In order to improve the computational efficiency, a particle swarm optimization (PSO) based algorithm is developed. The PSO allows a significant improvement in the computation time which makes it better suited for real-time damage localization. The proposed objective function is based on the exponential elliptical approach. First, the suitability of the PSO for damage localization is shown. Then the performance of the chosen objective function is compared with the brute-force algorithm as well as other objective functions found in the literature. The methodology is employed on a simple aluminum plate. The results indicate that indeed the objective function along with the PSO is suitable for damage localization. Also as the objective function is developed taking into consideration the specific challenges with the use of FBG sensors, performs better than the other objective functions as well as the brute force algorithm.
DA - 2022/8//
PY - 2022/8//
DO - 10.3390/s22166000
VL - 22
IS - 16
SP -
SN - 1424-8220
UR - https://www.mdpi.com/1424-8220/22/16/6000
KW - guided waves
KW - fiber Bragg grating (FBG) sensors
KW - remote bonding
KW - damage localization
KW - particle swarm optimization
ER -
TY - JOUR
TI - Cephalopod-inspired snapshot multispectral sensor based on geometric phase lens and stacked organic photodetectors
AU - Altaqui, Ali
AU - Schrickx, Harry
AU - Gyurek, Sydney
AU - Sen, Pratik
AU - Escuti, Michael
AU - Brendan T. O'Connor,
AU - Kudenov, Michael
T2 - OPTICAL ENGINEERING
AB - Multispectral imaging (MSI) is a valuable sensing modality for applications that require detecting a scene’s chemical characteristics. Existing MSI techniques utilize a filter wheel or color filter arrays, which are subject to reduced temporal or spatial resolution. In this work, we present a cephalopod-inspired multispectral organic sensor (CiMOS) based on geometric phase lenses (GPLs) and organic photovoltaics (OPVs) to enable aberration-based color sensing. We mimic the approach by which animals with single-type photoreceptors perceive colors via chromatic aberration. The intrinsic chromatic aberration of GPLs allows for multispectral sensing by stacking precisely patterned OPVs within specific spectrally dependent focal lengths. We provide simulations and a proof of concept of the CiMOS and highlight its advantages, including its simple design and snapshot multi-color detection using only a single axial position. Experimental results demonstrate the sensor’s ability to detect four colors with full width at half maximum spectral resolution as low as 35 nm.
DA - 2022/7/1/
PY - 2022/7/1/
DO - 10.1117/1.OE.61.7.077104
VL - 61
IS - 7
SP -
SN - 1560-2303
KW - multispectral sensing
KW - pancharatnam-berry phase
KW - organic photovoltaics
KW - geometric phase lens
KW - imaging
KW - sensors
KW - spectroscopy
ER -
TY - JOUR
TI - Exploration of the dislocation-electrochemistry relation in LiFePO4 cathode materials
AU - Chen, Hongjiang
AU - Kim, Sangwook
AU - Huang, Hsiao-Ying Shadow
T2 - ACTA MATERIALIA
AB - Defects, such as dislocations, in electrode materials play a significant role in the performance of lithium-ion batteries. The dislocation-electrochemistry relation has only been observed experimentally and not been fully clarified. Computational studies on this mechanism were also very limited, especially the altered cyclic voltammetry behaviors and associated effective diffusivity. This work focuses on the influences of few characteristics of dislocations on the electrochemical performance of an anisotropic cathode material, lithium iron phosphate (LiFePO 4 ). Utilizing linear elastic mechanics and the superposition principle, we study stress and displacement fields of a LiFePO 4 particle containing different densities and orientations of dislocations. With the mechanical-electrochemical coupling effects expressed by the modified Butler-Volmer equation and using the finite different method, the cyclic voltammetry curves for different dislocation configurations in the particle are investigated. Our results show that introducing dislocations can shift and distort the cyclic voltammetry curves, especially at one specific dislocation orientation. It is also found that the Li-ion molar fraction-dependent partial molar volume is an important prerequisite of the distortion in cyclic voltammetry curves. Moreover, the altered cyclic voltammetry curves at different scanning rates indicate the improvements of electrical power, stored electrical energy, and the effective diffusivity of lithium. Our discrete dislocation model indicates that the capacity loss of LiFePO 4 nanoparticles can be alleviated by introducing tailored dislocations. This study assists the understanding of electrode materials with pre-existing dislocations and provides strategies of using defect engineering to improve the kinetic performance in lithium-ion batteries.
DA - 2022/9/15/
PY - 2022/9/15/
DO - 10.1016/j.actamat.2022.118158
VL - 237
SP -
SN - 1873-2453
KW - Dislocations
KW - Cyclic voltammetry
KW - Electrochemistry
KW - Stress
KW - Displacement
KW - Lithium -ion battery
ER -
TY - JOUR
TI - Bidirectional, unlike unidirectional transport, allows transporting axonal cargos against their concentration gradient
AU - Kuznetsov, Ivan A.
AU - Kuznetsov, Andrey V
T2 - JOURNAL OF THEORETICAL BIOLOGY
AB - Even though most axonal cargos are synthesized in the soma, the concentration of many of these cargos is larger at the presynaptic terminal than in the soma. This requires transport of these cargos from the soma to the presynaptic terminal or other active sites in the axon. Axons utilize both bidirectional (for example, slow axonal transport) and unidirectional (for example, fast anterograde axonal transport) modes of cargo transport. Bidirectional transport seems to be less efficient because it requires more time and takes more energy to deliver cargos. In this paper, we studied a family of models which differ by the modes of axonal cargo transport (such as anterograde and retrograde motor-driven transport and passive diffusion) as well as by the presence or absence of pausing states. The models are studied to investigate their ability to describe axonal transport against the cargo concentration gradient. We argue that bidirectional axonal transport is described by a higher-order mathematical model, which allows imposing cargo concentration not only at the axon hillock but also at the axon terminal. The unidirectional transport model allows only for the imposition of cargo concentration at the axon hillock. Due to the great lengths of the axons, anterograde transport mostly relies on molecular motors, such as kinesins, to deliver cargos synthesized in the soma to the terminal and other active sites in the axon. Retrograde transport can be also motor-driven, in which case cargos are transported by dynein motors. If cargo concentration at the axon tip is higher than at the axon hillock, retrograde transport can also occur by cargo diffusion. However, because many axonal cargos are large or they assemble in multiprotein complexes for axonal transport, the diffusivity of such cargos is very small. We investigated the case of a small cargo diffusivity using a perturbation technique and found that for this case the effect of diffusion is limited to a very thin diffusion boundary layer near the axon tip. If cargo diffusivity is decreased in the model, we show that without motor-driven retrograde transport the model is unable to describe a high cargo concentration at the axon tip. To the best of our knowledge, our paper presents the first explanation for the utilization of seemingly inefficient bidirectional transport in neurons.
DA - 2022/8/7/
PY - 2022/8/7/
DO - 10.1016/j.jtbi.2022.111161
VL - 546
SP -
SN - 1095-8541
KW - Neuron
KW - Axon
KW - Mathematical modeling
KW - Slow and fast axonal transport
KW - Alpha-synuclein
ER -
TY - JOUR
TI - Cosserat modeling for deformation configuration of shape memory alloy unimorph actuators
AU - Kennedy, Scott
AU - Vlajic, Nicholas
AU - Perkins, Edmon
T2 - JOURNAL OF INTELLIGENT MATERIAL SYSTEMS AND STRUCTURES
AB - Shape memory alloys (SMAs) can contract their length via a crystalline phase transition that is dependent upon their temperature and stress state. SMAs have been used as linear micro-actuators due to their high strength to weight ratio and compact structure. However, the relatively low linear contraction ([Formula: see text]4%–5% in length) limits their use. To remedy this, the SMA can be offset from a passive structure, which acts to magnify the deformation. The resulting amount of deformation depends upon the material properties and geometry of both the SMA and the passive structure. In this work, geometrically exact beam theory (also known as Cosserat theory) is coupled with SMA constitutive relations to model the maximum deformation configuration of these actuators. Four of these actuators of various lengths were fabricated and tested to verify the model. For the four actuators tested, the mean squared error between the experimental results and the Cosserat model were between 0.0702 mm (0.1% error) for the shortest actuator (66 mm in length) and 3.59 mm (2.7% error) for the longest actuator (135 mm in length). These results show that the closed form solution derived for this Cosserat beam model can accurately model the deformation of these active structures.
DA - 2022/8/2/
PY - 2022/8/2/
DO - 10.1177/1045389X221109256
VL - 8
SP -
SN - 1530-8138
KW - Cosserat model
KW - geometrically exact beam theory
KW - shape memory alloy
KW - actuators
ER -
TY - JOUR
TI - Triptorelin-functionalized PEG-coated biosynthesized gold nanoparticles: Effects of receptor-ligand interactions on adhesion to triple negative breast cancer cells
AU - Uzonwanne, Vanessa O.
AU - Navabi, Arvand
AU - Obayemi, John D.
AU - Hu, Jingjie
AU - Salifu, Ali A.
AU - Ghahremani, Shahnaz
AU - Ndahiro, Nelson
AU - Rahbar, Nima
AU - Soboyejo, Winston
T2 - Biomaterials Advances
AB - This paper presents the results of an experimental and computational study of the adhesion of triptorelin-conjugated PEG-coated biosynthesized gold nanoparticles (GNP-PEG-TRP) to triple-negative breast cancer (TNBC) cells. The adhesion is studied at the nanoscale using a combination of atomic force microscopy (AFM) experiments and molecular dynamics (MD) simulations. The AFM measurements showed that the triptorelin-functionalized gold nanoparticles (GNP-TRP and GNP-PEG-TRP) have higher adhesion to triple-negative breast cancer cells (TNBC) than non-tumorigenic breast cells. The increased adhesion of GNP-TRP and GNP-PEG-TRP to TNBC is also attributed to the overexpression of LHRH receptors on the surfaces of both TNBC. Finally, the molecular dynamics model reveals insights into the effects of receptor density, molecular configuration, and receptor-ligand docking characteristics on the interactions of triptorelin-functionalized PEG-coated gold nanoparticles with TNBC. A three to nine-fold increase in the adhesion is predicted between triptorelin-functionalized PEG-coated gold nanoparticles and TNBC cells. The implications of the results are then discussed for the specific targeting of TNBC.
DA - 2022/4//
PY - 2022/4//
DO - 10.1016/j.bioadv.2022.212801
VL - 4
SP - 212801
UR - http://dx.doi.org/10.1016/j.bioadv.2022.212801
KW - Adhesion
KW - PEG-coated gold nanoparticles
KW - Molecular dynamic simulation
KW - Triptorelin
KW - AFM
KW - Triple negative breast cancer
ER -
TY - JOUR
TI - Investigation of creep properties and the cytoskeletal structures of non-tumorigenic breast cells and triple-negative breast cancer cells
AU - Onwudiwe, Killian
AU - Obayemi, John
AU - Hu, Jingjie
AU - Oparah, Josephine
AU - Onyekanne, Chinyerem
AU - Nwazojie, Chukwudalu
AU - Aina, Toyin
AU - Uzonwanne, Vanessa
AU - Salifu, Ali
AU - Soboyejo, Winston
T2 - Journal of Biomedical Materials Research Part A
AB - This article presents the correlation of creep and viscoelastic properties to the cytoskeletal structure of both tumorigenic and non-tumorigenic cells. Unique shear assay and strain mapping techniques were used to study the creep and viscoelastic properties of single non-tumorigenic and tumorigenic cells. At least 20 individual cells, three locations per cell, were studied. From the results, lower densities in the volume of actin, and keratin 18 structures were observed with the progression of cancer and were correlated to the increased creep rates and reduced mechanical properties (Young's moduli and viscosities) of tumorigenic (MDA-MB-231) cells. The study reveals significant differences between the creep and viscoelastic properties of non-tumorigenic breast cells versus tumorigenic cells. The variations in the creep strain rates are shown to be well characterized by lognormal distributions, while the statistical variations in the viscoelastic properties are well-described by normal distributions. The implications of the results are discussed for the study of discrete cell behaviors, strain and viscoelastic responses of the cell, and the role of cell cytoskeleton in the onset and progression of cancers.
DA - 2022/5//
PY - 2022/5//
DO - 10.1002/jbm.a.37348
VL - 110
IS - 5
SP - 1004-1020
UR - http://dx.doi.org/10.1002/jbm.a.37348
KW - cancer detection
KW - cell viscoelastic
KW - creep properties
KW - confocal microscopy
KW - cytoskeletal proteins
KW - immunofluorescence staining
KW - relative volume density
KW - shear assay
ER -
TY - JOUR
TI - High streamwise airfoil oscillations at constant low and high incidence angles
AU - Elfering, Kelsey
AU - Narsipur, Shreyas
AU - Granlund, Kenneth
T2 - PHYSICS OF FLUIDS
AB - Ratios of streamwise airfoil oscillations to the freestream velocity above 30% have not been well investigated in the literature for a reduced frequency range relevant to unsteady applications. A known departure from the experimental correlation to analytical theory for lower magnitudes of this ratio, known as surge amplitude, motivates a parameter study for constant freestream, at constant low- and high-incidence angles, to understand the circulatory lift dependence on angle of attack, Reynolds number, surge amplitude, and reduced frequency in comparison with theory and higher-order computations. To better understand the increased deviation between theory and experiment with increasing velocity fluctuation, a detailed study of surge amplitude of 0.5 is investigated. The experiment for comparison was a free-surface water tunnel with a NACA (National Advisory Committee for Aeronautics) 0018 airfoil oscillated in the streamwise direction. Force measurements, normalized by instantaneous dynamic pressure, reveal that unsteady lift is dependent on Reynolds number and reduced frequency in both attached and fully separated conditions. In separated conditions, mean and fluctuating lift show a dependency on reduced frequency for larger velocity fluctuations than a relative surge amplitude of 10%. Two-dimensional computations were found to agree well with experimental data for Reynolds number 75 k, low incidence cases, and for high incidence with reduced frequencies less than 0.15, where a fully separated upper surface boundary layer condition occurred. Agreement between computations and experiments was not favorable for reduced frequencies above 0.15 for high incidence cases, where partial upper surface boundary layer reattachment is predicted.
DA - 2022/8//
PY - 2022/8//
DO - 10.1063/5.0097570
VL - 34
IS - 8
SP -
SN - 1089-7666
UR - https://doi.org/10.1063/5.0097570
ER -
TY - JOUR
TI - A reconstructed discontinuous Galerkin method based on variational formulation for compressible flows
AU - Li, Lingquan
AU - Liu, Xiaodong
AU - Luo, Hong
T2 - JOURNAL OF COMPUTATIONAL PHYSICS
AB - A new reconstructed discontinuous Galerkin (rDG) method based on variational formulation is developed for compressible flows. In the presented method, a higher-order piece-wise polynomial is reconstructed based on the underlying discontinuous Galerkin (DG) solution. This reconstruction is done by using a newly developed variational formulation. The variational reconstruction (VR) can be seen as an extension of the compact finite difference (FD) schemes to unstructured grids. The reconstructed variables are obtained by solving an extreme-value problem, which minimizes the jumps of the reconstructed piece-wise polynomials across the cell interfaces, and therefore maximizes the smoothness of the reconstructed solution. Intrinsically, the stencils of the presented reconstruction are the entire mesh, so this method is robust even on tetrahedral grids. A variety of benchmark test cases are presented to assess the accuracy, efficiency and robustness of this rDG method. The numerical experiments demonstrate that the developed rDG method based on variational formulation can maintain the linear stability, obtain the designed high-order accuracy, and outperform the rDG counterpart based on the least-squares reconstruction for both inviscid and viscous compressible flows.
DA - 2022/10/1/
PY - 2022/10/1/
DO - 10.1016/j.jcp.2022.111406
VL - 466
SP -
SN - 1090-2716
KW - ReconstructeddiscontinuousGalerkin
KW - Variationalreconstruction
KW - High-order
KW - Compactreconstruction
KW - Interfacialjumpintegration
ER -
TY - JOUR
TI - Improvement of piezoelectric properties of relaxor type 0.695Pb(Mg1/3Nb2/3)O-3-0.305 PbTiO3 single crystal plate and silver vibrator by alternating current poling
AU - Wang, Zhuangkai
AU - Yamashita, Yohachi
AU - Sun, Yiqin
AU - Fujii, Tadashi
AU - Karaki, Tomoaki
T2 - JAPANESE JOURNAL OF APPLIED PHYSICS
AB - Abstract Alternating current poling (ACP) and direct current poling (DCP) on [001]-oriented 0.695Pb(Mg 1/3 Nb 2/3 )O 3 −0.305PbTiO 3 (PMN-0.305PT) single crystal (SC) plates with a dimension of 12 × 4 × 0.3 mm and silver vibrators of 12 × 0.15 × 0.3 mm were investigated. The highest dielectric constant of 14500 and piezoelectric constant of 4200 pCN −1 were confirmed with the ACP SC plate manufactured by the conventional one charge Bridgman process. After array dicing into silver, the silver mode coupling coefficient k’ 33 = 94.3% was obtained from ACP SC. However, many spurious mode vibrations (SMV) were seen in the impedance spectra of the DCP and ACP SC silver vibrators. We consider that this SMV may be caused by array dicing damage. The PMN-0.305PT SC plate near the morphotropic phase boundary shows excellent piezoelectric and dielectric properties, however, these silvers tend to show SMV after dicing. This information is useful to select the PMN-PT composition for medical probe application.
DA - 2022/11/1/
PY - 2022/11/1/
DO - 10.35848/1347-4065/ac7c52
VL - 61
IS - SN
SP -
SN - 1347-4065
KW - alternating current poling
KW - relaxor ferroelectric single crystal
KW - PMN-PT
KW - silver vibrator
ER -
TY - JOUR
TI - Hydrogen gas dispersion studies for hydrogen fuel cell vessels II: Fuel cell room releases and the influence of ventilation
AU - Gitushi, K. M.
AU - Blaylock, M. L.
AU - Klebanoff, L. E.
T2 - INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
AB - Results are presented for computational fluid dynamics (CFD) modeling for varying hydrogen leaks within a hydrogen vessel's Fuel Cell Rack inside a Fuel Cell Room. In the limiting case of no room ventilation, modeling shows that the flammable region produced by the hydrogen leak is initially limited by self-induced entrainment and recirculation of air caused by the buoyant rising of hydrogen. Locally and at shorter times (minutes), this effect can be even more influential in limiting the size of the flammable envelope than Fuel Cell Room ventilation. Interestingly, the more diffuse detectable (but sub-flammable) region is not self-limited. This indicates the recirculation pattern required for the self-limiting effect requires a sufficient concentration of hydrogen to establish and differentiate the rising hydrogen mass from the surrounding air, thereby establishing the recirculation pattern that self-limits the flammable region at short times. Modeling results with the Fuel Cell Room ventilation activated shows that several seconds after a hydrogen leak is initiated, the flammable region reaches a steady state, with only minor fluctuations due to the air currents created by ventilation. The expected trends with ventilation rate are found: for a given leak size, a decreasing flammable envelope is found as ventilation is increased and for a given level of ventilation, an increasing hydrogen leak rate produces a larger flammable region. For the cases and ventilation rates examined, flammable H2/air mixtures greater than 4% clear the Fuel Cell Room within 1.5 s after the hydrogen leak is turned off. The CFD modeling results for the detectable level of hydrogen that would trigger an alarm showed that higher ventilation rates might have the unintended consequence of making a hydrogen leak harder to detect, depending on the location of the gas detector in the Fuel Cell Room For the hydrogen leak rates considered in this study, we find that a ventilation rate of 15 ACH provides timely hydrogen evacuation while allowing the leak to be detected by the ceiling-mounted hydrogen monitor (for most monitor locations).
DA - 2022/6/12/
PY - 2022/6/12/
DO - 10.1016/j.ijhydene.2022.04.263
VL - 47
IS - 50
SP - 21492-21505
SN - 1879-3487
KW - Hydrogen gas dispersion
KW - Room ventilation
KW - Hydrogen fuel cells
KW - Hydrogen vessels
KW - Hydrogen leak detection
ER -
TY - JOUR
TI - Sensitivity analysis guided improvement of an electromyogram-driven lumped parameter musculoskeletal hand model
AU - Hinson Jr, Robert Jr
AU - Saul, Katherine
AU - Kamper, Derek
AU - Huang, He
T2 - JOURNAL OF BIOMECHANICS
AB - EMG-driven neuromusculoskeletal models have been used to study many impairments and hold great potential to facilitate human–machine interactions for rehabilitation. A challenge to successful clinical application is the need to optimize the model parameters to produce accurate kinematic predictions. In order to identify the key parameters, we used Monte-Carlo simulations to evaluate the sensitivities of wrist and metacarpophalangeal (MCP) flexion/extension prediction accuracies for an EMG-driven, lumped-parameter musculoskeletal model. Four muscles were modeled with 22 total optimizable parameters. Model predictions from EMG were compared with measured joint angles from 11 able-bodied subjects. While sensitivities varied by muscle, we determined muscle moment arms, maximum isometric force, and tendon slack length were highly influential, while passive stiffness and optimal fiber length were less influential. Removing the two least influential parameters from each muscle reduced the optimization search space from 22 to 14 parameters without significantly impacting prediction correlation (wrist: 0.90 ± 0.05 vs 0.90 ± 0.05, p = 0.96; MCP: 0.74 ± 0.20 vs 0.70 ± 0.23, p = 0.51) and normalized root mean square error (wrist: 0.18 ± 0.03 vs 0.19 ± 0.03, p = 0.16; MCP: 0.18 ± 0.06 vs 0.19 ± 0.06, p = 0.60). Additionally, we showed that wrist kinematic predictions were insensitive to parameters of the modeled MCP muscles. This allowed us to develop a novel optimization strategy that more reliably identified the optimal set of parameters for each subject (27.3 ± 19.5%) compared to the baseline optimization strategy (6.4 ± 8.1%; p = 0.004). This study demonstrated how sensitivity analyses can be used to guide model refinement and inform novel and improved optimization strategies, facilitating implementation of musculoskeletal models for clinical applications.
DA - 2022/8//
PY - 2022/8//
DO - 10.1016/j.jbiomech.2022.111200
VL - 141
SP -
SN - 1873-2380
KW - Musculoskeletal modeling
KW - Optimization
KW - Upper limb
KW - Rehabilitation
KW - Musculoskeletal modeling
KW - Optimization
KW - Upper limb
KW - Rehabilitation
ER -
TY - JOUR
TI - Evaluating anthropometric scaling of a generic adult model to represent pediatric shoulder strength
AU - Dalman, Morgan
AU - Liao, Ashlee
AU - Saul, Katherine R.
T2 - JOURNAL OF BIOMECHANICS
AB - The structure of the developing musculoskeletal system during childhood and adolescence influences tissue loading and function. Anatomical features important for musculoskeletal loading such as muscle volume and limb proportion vary with age but limited available anatomical data for the developing limb makes predicting loads challenging. Our aim was to evaluate whether anthropometric scaling of an existing adult musculoskeletal upper limb model is sufficient to accurately represent pediatric strength. An adult upper limb model was scaled using two scale factors based on length features and max isometric force (MIF). Length features (e.g. limb and muscle length) were scaled based on linear regression for available literature reports of forearm length vs. height (N = 366 Pediatric, N = 107 Adults), while MIF was scaled based on relating body mass vs. total shoulder muscle volume (N = 6). Children-specific models were developed for 6 pediatric individuals whose height, body mass, and shoulder moment-generating capacity (a common measure of strength) were previously reported. These models were used to predict isometric shoulder moments for flexion/extension, internal/external rotation, and ad/abduction and compared with physical measurements previously reported. The predicted isometric shoulder moments were significantly correlated to measured moments for these same individuals (p < 0.04, r2 > 0.7). However, predicted moments tended to underestimate measured values; shoulder external rotation was most accurately predicted (slope: 1.1234) while shoulder adduction was most underestimated (slope: 0.4624). This work provides an initial basis for pediatric scaling but illustrates the important need for additional direct measures of muscle size and limb strength and function in a pediatric population.
DA - 2022/8//
PY - 2022/8//
DO - 10.1016/j.jbiomech.2022.111170
VL - 141
SP -
SN - 1873-2380
KW - Anthropometrics
KW - Pediatric
KW - Upper limb
KW - Modeling
KW - Shoulder
KW - Anthropometrics
KW - Pediatric
KW - Upper limb
KW - Modeling
KW - Shoulder
ER -
TY - JOUR
TI - Hidden damage visualization using laser speckle photometry
AU - Welzen, J.
AU - Yuan, F. G.
AU - Fong, R. Y.
T2 - NDT & E INTERNATIONAL
AB - This paper exploits laser speckle photometry (LSP), a full-field non-contact optical-based image analysis technique, for effectively and rapidly imaging hidden damage in structures, rather than with the complex setups in digital speckle pattern interferometry (DSPI) or shearography (SG)-based interferometry. This technique will demonstrate a promising potential for large-area inspection of composite structures in near real time to unearth barely visible impact damage (BVID) which would typically go unnoticed during routine inspections. Three image (processing) algorithms for localizing and then imaging the BVID area were explored: conventional mean squared error (MSE), normalized cross-correlation (NCC), and an index-centered algorithm known as structural similarity index measure (SSIM). When implementing these algorithms in LSP, a pre-processing step of selecting a window size (subregion size) for locally correlating the images to localize the damage and estimate its size was performed as an advancement on the previous pixel-by-pixel correlations made with LSP. A trade-off strategy between two perceptual-based metrics, image fidelity and image sharpness/blurriness, was implemented to evaluate an appropriate range for window sizes followed by the image algorithms for creating high contrast imaging of damage regions. From the correlation map, the strategy was carried out to mitigate image noise caused by the camera (image) sensors and speckle patterns dictated by the overall root-mean-square deviation (RMSD) while maintaining a high level of sharpness characterized by the magnitude of the third-level discrete wavelet transform. The proposed image algorithms in conjunction with the appropriately selected window size served as imaging conditions in the context of laser speckles for the first time and were tested on BVID in an impacted honeycomb composite panel under thermal excitation. A low coherence (high-power) laser for fast screening of a large area, if required, followed by a high coherence (low-power laser) for detailed imaging were used to demonstrate the efficacy of LSP. The damage image region agreed well with a baseline image from the well-established point-by-point CT-scan with all the three image algorithms. Overall, NCC and SSIM performed slightly better than MSE, with SSIM generally being the better of the two. Nevertheless, MSE has its merits with ease of interpretation and implementation. LSP with the proposed imaging conditions shows enormous potential as a real-time non-destructive inspection (NDI) technique not only in the aerospace industry but also in industries such as additive manufacturing where on-line in-situ monitoring is desired for prevalent defects. The real-time inspection using LSP will further allow immediate feedback for process controls.
DA - 2022/10//
PY - 2022/10//
DO - 10.1016/j.ndteint.2022.102700
VL - 131
SP -
SN - 1879-1174
UR - http://dx.doi.org/10.1016/j.ndteint.2022.102700
KW - Laser speckle photometry
KW - Barely visible impact damage
KW - Mean squared error
KW - Normalized cross correlation
KW - Structural similarity index measure
KW - Honeycomb composite panel
KW - Optimized window size
ER -
TY - JOUR
TI - Editorial: Next Generation User-Adaptive Wearable Robots
AU - Bulea, Thomas C.
AU - Sharma, Nitin
AU - Sikdar, Siddhartha
AU - Su, Hao
T2 - FRONTIERS IN ROBOTICS AND AI
AB - EDITORIAL article Front. Robot. AI, 22 June 2022Sec. Biomedical Robotics https://doi.org/10.3389/frobt.2022.920655
DA - 2022/6/22/
PY - 2022/6/22/
DO - 10.3389/frobt.2022.920655
VL - 9
SP -
SN - 2296-9144
KW - exoskeleton
KW - wearable robot
KW - rehabilitation
KW - human-in-the loop
KW - functional electric stimulation
ER -
TY - JOUR
TI - Can the lack of fibrillar form of alpha-synuclein in Lewy bodies be explained by its catalytic activity?
AU - Kuznetsov, Ivan A.
AU - Kuznetsov, Andrey V
T2 - MATHEMATICAL BIOSCIENCES
AB - Finding the causative pathophysiological mechanisms for Parkinson’s disease (PD) is important for developing therapeutic interventions. Until recently, it was believed that Lewy bodies (LBs), the hallmark of PD, are mostly composed of alpha-synuclein (α-syn) fibrils. Recent results (Shahmoradian et al. (2019)) demonstrated that the fibrillar form of α-syn is lacking from LBs. Here we propose that this surprising observation can be explained by the catalytic activity of the fibrillar form of α-syn. We assumed that α-syn fibrils catalyze the formation of LBs, but do not become part of them. We developed a mathematical model based on this hypothesis. By using the developed model, we investigated the consequences of this hypothesis. In particular, the model suggests that the long incubation time of PD can be explained by a two-step aggregation process that leads to its development: (i) aggregation of monomeric α-syn into α-syn oligomers and fibrils and (ii) clustering of membrane-bound organelles, which may cause disruption of axonal trafficking and lead to neuron starvation and death. The model shows that decreasing the rate of destruction of α-syn aggregates in somatic lysosomes accelerates the formation of LBs. Another consequence of the model is the prediction that removing α-syn aggregates from the brain after the aggregation of membrane-bound organelles into LBs has started may not stop the progression of PD because LB formation is an autocatalytic process; hence, the formation of LBs will be catalyzed by aggregates of membrane-bound organelles even in the absence of α-syn aggregates. The performed sensitivity study made it possible to establish the hierarchy of model parameters with respect to their effect on the formation of vesicle aggregates in the soma.
DA - 2022/2//
PY - 2022/2//
DO - 10.1016/j.mbs.2021.108754
VL - 344
SP -
SN - 1879-3134
KW - Neuron
KW - Axon
KW - Parkinson's disease
KW - Mathematical modeling
KW - Alpha-synuclein
ER -
TY - JOUR
TI - Sparsifying the resolvent forcing mode via gradient-based optimisation
AU - Skene, Calum S.
AU - Yeh, Chi-An
AU - Schmid, Peter J.
AU - Taira, Kunihiko
T2 - JOURNAL OF FLUID MECHANICS
AB - We consider the use of sparsity-promoting norms in obtaining localised forcing structures from resolvent analysis. By formulating the optimal forcing problem as a Riemannian optimisation, we are able to maximise cost functionals whilst maintaining a unit-energy forcing. Taking the cost functional to be the energy norm of the driven response results in a traditional resolvent analysis and is solvable by a singular value decomposition (SVD). By modifying this cost functional with the $L_1$ -norm, we target spatially localised structures that provide an efficient amplification in the energy of the response. We showcase this optimisation procedure on two flows: plane Poiseuille flow at Reynolds number $Re=4000$ , and turbulent flow past a NACA 0012 aerofoil at $Re=23\,000$ . In both cases, the optimisation yields sparse forcing modes that maintain important features of the structures arising from an SVD in order to provide a gain in energy. These results showcase the benefits of utilising a sparsity-promoting resolvent formulation to uncover sparse forcings, specifically with a view to using them as actuation locations for flow control.
DA - 2022/7/6/
PY - 2022/7/6/
DO - 10.1017/jfm.2022.519
VL - 944
SP -
SN - 1469-7645
KW - shear-flow instability
KW - instability control
ER -
TY - JOUR
TI - Low-Order Modeling of Wingtip Vortices in a Vortex Lattice Method
AU - Loewenthal, Ethan
AU - Gopalarathnam, Ashok
T2 - AIAA JOURNAL
AB - Wingtip-flow effects on the aerodynamic forces and moments of a wing become increasingly significant as the aspect ratio decreases. These effects are dominated by the tip vortex and an associated suction zone, which results in a supplementary “vortex lift” that is not captured by conventional vortex lattice methods (VLMs). Although many augmented VLMs have addressed such free-vortical flows on the leading edges of delta wings and even wingtips, they do not account for the portion of the vorticity that may be supported by the attached flow at the tip. The current work consists of an augmented VLM designed to capture the geometry and strength of the free tip vortex along the wingtip, and it is distinguished from prior models by the capability to allocate vorticity between the bound wingtip flow and the free tip-vortex flow at each chordwise position. This paper presents the model and its predictions of tip-vortex positions, as well as forces and moments on low-aspect-ratio wings. The model demonstrates lift distributions typical of vortex lift, promising agreement with forces and moments from experimental work as well as modulation of the forces and moments by selection of the maximum allowable bound vorticity along the tips.
DA - 2022/3//
PY - 2022/3//
DO - 10.2514/1.J060654
VL - 60
IS - 3
SP - 1708-1720
SN - 1533-385X
ER -
TY - JOUR
TI - Effects of subject-variability on nasally inhaled drug deposition, uptake, and clearance
AU - Chari, Sriram
AU - Sridhar, Karthik
AU - Kleinstreuer, Clement
T2 - JOURNAL OF AEROSOL SCIENCE
AB - Accurate and realistic predictions of the fate of nasally inhaled generic drugs provide new physical insight which can be of great importance to toxicologists, drug developers and federal regulators alike. To understand the dynamics of mucociliary clearance (MCC) and subsequent absorption of the dissolved drug by the nasal epithelium, it becomes necessary to model the air-particle-mucus dynamics accurately. The MCC process, including particle dissolution, transport and absorption for a 3-D representative nasal cavity, were established by Chari et al. (2021). In this study, the effects of inter-subject variability of three representative nasal cavities (subjects A, B, C) on deposition and subsequent uptake of the dissolved drug in the nasal epithelium are analyzed for three generic drugs: Mometasone furoate (MF), Flunisolide (FN), and Ribavirin (RB). The computational fluid-particle dynamics (CF-PD) results indicate that smaller sized particles (3 μm) deposit more in the ciliated portion of the nasal cavity where the columnar cells responsible for uptake are present. In contrast, larger particles (10 μm) tend to deposit in the unciliated anterior third of the nose. The epithelial uptake in case of subject A was considerably higher than that in subjects B and C because of the unique anatomical characteristics of subject A. Also, FN and RB were found to have a higher rate of uptake compared to MF due to their considerably higher partition coefficient. As a visualization tool, concentration contours are used to explain regional trends in cumulative drug uptake for all three cases. • The open-source CFD toolbox, OpenFOAM, has been employed for the development of the computer simulation model. • This study illustrates the effects of inter-subject variability on deposition, dissolution and uptake of 3 generic drugs in representative nasal cavity models. • Smaller particles, with their relatively large surface area, tend to dissolve quicker and are absorbed more rapidly than larger particles. • Particles deposited closer to the ciliated portion of the nasal cavity are more readily absorbed when compared to particles deposited closer to the unciliated nasal vestibule.
DA - 2022/9//
PY - 2022/9//
DO - 10.1016/j.jaerosci.2022.106021
VL - 165
SP -
SN - 1879-1964
KW - Nasal geometric variabilities
KW - CF-PD analysis With updated OpenFOAM
KW - solver
KW - Inhaled drug-aerosol transport and uptake
KW - Mucus layer dynamics
KW - Mucociliary clearance
KW - Dissolution and absorption of three generic
KW - drugs
ER -
TY - JOUR
TI - The pendulum adaptive frequency oscillator
AU - Li, XiaoFu
AU - Kallepalli, Pawan
AU - Mollik, Tushar
AU - Ul Shougat, Md Raf E
AU - Kennedy, Scott
AU - Frabitore, Sean
AU - Perkins, Edmon
T2 - Mechanical Systems and Signal Processing
AB - Adaptive oscillators are a type of nonlinear oscillator that are capable of learning and storing information in plastic states. Here, a typical mechanical pendulum is modified to have an adjustable rod length to create a pendulum adaptive frequency oscillator. Since the resonance frequency of the pendulum is a function of the rod length, this allows the pendulum to learn and encode frequency information from an external source. An experimental pendulum adaptive frequency oscillator is designed and constructed, and its performance is compared to numerical simulations. This nonlinear pendulum was approximated as a Duffing oscillator through the method of multiple scales to determine the physical constants of the experiment by using a curve fit. Utilizing the pendulum adaptive frequency oscillator’s dynamics, this system is able to learn a resonance condition and store this information in the rod length. This causes the system to seek resonance, even with considerable nonlinearity. As pendulums can be used to harvest energy, this type of adaptation could be used to further exploit vibratory energy sources.
DA - 2022/11/1/
PY - 2022/11/1/
DO - 10.1016/j.ymssp.2022.109361
VL - 179
SP - 109361
SN - 1096-1216
KW - Adaptive oscillators
KW - Pendulum
KW - Duffing oscillator
KW - Electromechanical system
ER -
TY - JOUR
TI - Finite element study of the impact of pedicle screw density on the biomechanical response of a Lenke 1AN scoliotic curve
AU - Warren, Justin M.
AU - Hey, Lloyd A.
AU - Mazzoleni, Andre P.
T2 - JOURNAL OF ORTHOPAEDICS
AB - Benefits of increasing screw density in posterior instrumentation used to treat a scoliotic deformity are demonstrated using a three-dimensional finite element model (FEM) of the thoracolumbosacral spine. The FEM represents a Lenke 1AN scoliotic deformity with a 50° Cobb angle and 20° apical vertebral rotation. The curve is corrected with bilateral pedicle screw fixation and 75 separate randomized screw distributions. Total construct screw density, concave rod screw locations at T6, T10, T11 and T12, and convex rod screw locations at T7 and T12 each correlate strongly with reductions in postoperative Cobb angle (P < 0.05). Apical vertebral rotation is greatly impacted (reduced) by screws placed at the apical vertebra on both concave and convex rods (P < 0.05). Under pure moment loading, intersegmental micromotion is generally reduced when motion segment screw density is increased, with the exception being the upper instrumented joint. These results suggest that increasing the screw density of posterior constructs used to treat a Lenke 1AN scoliotic deformity may improve the de-rotation correction with better postural restoration, reducing the risk of future complications including pseudarthrosis.
DA - 2022///
PY - 2022///
DO - 10.1016/j.jor.2022.05.012
VL - 32
SP - 92-97
SN - 0972-978X
KW - Finite element analysis
KW - Scoliosis
KW - Pedicle screw
KW - Micromotion
ER -
TY - JOUR
TI - Silver Nanowire Composite Electrode Enabling Highly Flexible, Robust Organic Photovoltaics
AU - Booth, Ronald E.
AU - Schrickx, Harry M.
AU - Hanby, Georgia
AU - Liu, Yuxuan
AU - Qin, Yunpeng
AU - Ade, Harald
AU - Zhu, Yong
AU - Brendan T. O'Connor,
T2 - SOLAR RRL
AB - Using Ag nanowires (NWs) is a promising approach to make flexible and transparent conducting electrodes for organic photovoltaics (OPVs). However, the roughness of the NWs can decrease device performance. Herein, a Ag NW electrode embedded in a UV‐curable epoxy that uses a simple mechanical lift‐off process resulting in highly planar electrodes is demonstrated. A bimodal blend of Ag NWs with varying aspect ratios is used to optimize the transparency and conductivity of the electrode. In addition, a ZnO layer is coated on the Ag NWs prior to the embedding process to ensure low contact resistance in the OPV cells. The resulting resin‐embedded ZnO‐encapsulated silver nanowire (REZEN) electrode is found to have excellent mechanical stability. REZEN electrode‐based OPV cells exhibit comparable performance with reference devices, achieving maximum power conversion efficiency (PCE) of 13.5% and 13.6% respectively. The REZEN‐based OPV cells are also mechanically robust, retaining 97% of their PCE after 5000 cycles at R = 1.2 mm and 94% PCE after 1000 cycles at R = 0.55 mm. This flexibility is among the highest reported for freestanding devices. Thus, the REZEN electrode is a promising and simple strategy to achieve mechanically robust ITO‐free flexible OPV cells.
DA - 2022/6/15/
PY - 2022/6/15/
DO - 10.1002/solr.202200264
SP -
SN - 2367-198X
KW - flexible organic photovoltaics
KW - flexible transparent electrodes
KW - mechanically stable organic photovoltaics
KW - organic solar cells
KW - silver nanowire electrodes
ER -
TY - JOUR
TI - Design and Backdrivability Modeling of a Portable High Torque Robotic Knee Prosthesis With Intrinsic Compliance for Agile Activities
AU - Zhu, Junxi
AU - Jiao, Chunhai
AU - Dominguez, Israel
AU - Yu, Shuangyue
AU - Su, Hao
T2 - IEEE-ASME TRANSACTIONS ON MECHATRONICS
AB - High-performance prostheses are crucial to enable versatile activities like walking, squatting, and running for lower extremity amputees. State-of-the-art prostheses are either not powerful enough to support demanding activities or have low compliance (low backdrivability) due to the use of high speed ratio transmission. Besides speed ratio, gearbox design is also crucial to the compliance of wearable robots, but its role is typically ignored in the design process. This paper proposed an analytical backdrive torque model that accurately estimate the backdrive torque from both motor and transmission to inform the robot design. Following this model, this paper also proposed methods for gear transmission design to improve compliance by reducing inertia of the knee prosthesis. We developed a knee prosthesis using a high torque actuator (built-in 9:1 planetary gear) with a customized 4:1 low-inertia planetary gearbox. Benchtop experiments show the backdrive torque model is accurate and proposed prosthesis can produce 200 Nm high peak torque (shield temperature <60°C), high compliance (2.6 Nm backdrive torque), and high control accuracy (2.7/8.1/1.7 Nm RMS tracking errors for 1.25 m/s walking, 2 m/s running, and 0.25 Hz squatting, that are 5.4%/4.1%/1.4% of desired peak torques). Three able-bodied subject experiments showed our prosthesis could support agile and high-demanding activities.
DA - 2022/6/3/
PY - 2022/6/3/
DO - 10.1109/TMECH.2022.3176255
VL - 6
SP -
SN - 1941-014X
UR - http://dx.doi.org/10.1109/tmech.2022.3176255
KW - Torque
KW - Brushless DC motors
KW - Actuators
KW - Gears
KW - Prosthetics
KW - Robots
KW - Rotors
KW - Backdrive torque modeling
KW - high compliance
KW - high torque actuator
KW - powered prosthesis
KW - wearable robots
ER -
TY - JOUR
TI - Using ultrasonic attenuation in cortical bone to infer distributions on pore size
AU - White, R. D.
AU - Alexanderian, A.
AU - Yousefian, O.
AU - Karbalaeisadegh, Y.
AU - Bekele-Maxwell, K.
AU - Kasali, A.
AU - Banks, H. T.
AU - Talmant, M.
AU - Grimal, Q.
AU - Muller, M.
T2 - APPLIED MATHEMATICAL MODELLING
AB - In this work we infer the underlying distribution on pore radius in human cortical bone samples using ultrasonic attenuation data. We first discuss how to formulate polydisperse attenuation models using a probabilistic approach and the Waterman Truell model for scattering attenuation. We then compare the Independent Scattering Approximation and the higher-order Waterman Truell models’ forward predictions for total attenuation in polydisperse samples. Following this, we formulate an inverse problem under the Prohorov Metric Framework coupled with variational regularization to stabilize this inverse problem. We then use experimental attenuation data taken from human cadaver samples and solve inverse problems resulting in nonparametric estimates of the probability density function on pore radius. We compare these estimates to the “true” microstructure of the bone samples determined via microCT imaging. We find that our methodology allows us to reliably estimate the underlying microstructure of the bone from attenuation data.
DA - 2022/9//
PY - 2022/9//
DO - 10.1016/j.apm.2022.05.024
VL - 109
SP - 819-832
SN - 1872-8480
KW - Ultrasound
KW - Cortical bone
KW - Polydisperse
KW - Waterman truell
KW - Inverse problems
KW - Variational regularization
ER -
TY - JOUR
TI - A Fused Gaussian Process Modeling and Model Predictive Control Framework for Real-Time Path Adaptation of an Airborne Wind Energy System
AU - Siddiqui, Ayaz
AU - Borek, John
AU - Vermillion, Chris
T2 - IEEE TRANSACTIONS ON CONTROL SYSTEMS TECHNOLOGY
AB - This article presents a computationally tractable adaptive control strategy suitable for mobile systems operating in a stochastically and spatiotemporally varying environment by fusing Gaussian process modeling and receding horizon control. This strategy ideally manages the tradeoff between exploration (maintaining an accurate estimate of the stochastic resource) and exploitation (maximizing a performance index, which generally consists of harvesting the resource) subject to partial observability (stochastic resource only measurable at the system’s location) and mobility constraints, which are characteristic of dynamic systems. The case study in this article focuses on a crosswind airborne wind energy (AWE) system where the wind turbine tower is replaced by tethers and a lifting body, allowing the system to adjust its altitude, with the goal of operating at the altitude that maximizes net energy production in a wind environment that is changing in altitude and time. Real wind speed versus altitude data has been used to validate the strategy and results are presented for a variety of control strategies applied to a rigid wing-based AWE system.
DA - 2022/6/6/
PY - 2022/6/6/
DO - 10.1109/TCST.2022.3178038
SP -
SN - 1558-0865
KW - Wind speed
KW - Wind power generation
KW - Real-time systems
KW - Optimization
KW - Gaussian processes
KW - Adaptation models
KW - Wind turbines
KW - Adaptive control
KW - stochastic processes
KW - and wind energy generation
ER -
TY - JOUR
TI - POLYVINYL ALCOHOL CRYOGELS FOR ACOUSTIC CHARACTERIZATION OF PHASE-CHANGE CONTRAST AGENTS
AU - Durham, Phillip G.
AU - Kim, Jinwook
AU - Eltz, Katherine M.
AU - Caskey, Charles F.
AU - Dayton, Paul A.
T2 - ULTRASOUND IN MEDICINE AND BIOLOGY
AB - Phase-change contrast agents (PCCAs) consisting of lipid-encapsulated low-boiling-point perfluorocarbons can be used in conjunction with ultrasound for diagnostic and therapeutic applications. One benefit of PCCAs is site-specific activation, whereby the liquid core is acoustically vaporized into a bubble detectable via ultrasound imaging. For further evaluation of PCCAs in a variety of applications, it is useful to disperse these nanodroplets into an acoustically compatible stationary matrix. However, many traditional phantom preparations require heating, which causes premature thermal activation of low-boiling-point PCCAs. Polyvinyl alcohol (PVA) cryogels do not require heat to set. Here we propose a simple method for the incorporation of the low-boiling-point PCCAs using octafluoropropane (OFP) and decafluorobutane (DFB) into PVA cryogels for a variety of acoustic characterization applications. We determined the utility of the phantoms by activating droplets with a focused transducer, visualizing the lesions with ultrasound imaging. At 1 MHz, droplet activation was consistently observed at 2.0 and 4.0 MPa for OFP and DFB, respectively.
DA - 2022/5//
PY - 2022/5//
DO - 10.1016/j.ultrasmedbio.2022.01.007
VL - 48
IS - 5
SP - 954-960
SN - 1879-291X
KW - Phase-change contrast agent
KW - Nanodroplets
KW - Polyvinyl alcohol cryogel
ER -
TY - JOUR
TI - Development of Viscoelastic Damper Based on NBR and Organic Small-Molecule Composites
AU - Ge, Teng
AU - Xu, Zhao-Dong
AU - Yuan, Fuh-Gwo
T2 - JOURNAL OF MATERIALS IN CIVIL ENGINEERING
AB - Viscoelastic (VE) damper is usually vulcanized by mixing polymer matrix, additives, and fillers, all of which have a great influence on the viscoelastic response of the material. In this study, a series of novel samples of VE materials have been produced by adding different kinds and amounts of organic small molecule modifiers (AO1035, AO60, and AO80) to neat nitrile-butadiene rubber (NBR). The mechanical properties of VE materials have been tested on a dynamic mechanical analyzer and universal testing tensile machine, and the most excellent formulation was selected for manufacturing VE damper. The dynamic mechanical properties of the VE material in the damper with amplitude and frequency are tested and analyzed. The results indicate that the VE damper has a high energy dissipation capacity. To clarify the dynamic mechanical properties of the novel VE material, a high-order fractional derivative model is proposed, which considers the effects of amplitude and frequency simultaneously based on the energy dissipation mechanism of the novel VE material. Finally, the calculated results using this model are compared with the tested data, which has verified the correctness of the mathematical model.
DA - 2022/8/1/
PY - 2022/8/1/
DO - 10.1061/(ASCE)MT.1943-5533.0004339
VL - 34
IS - 8
SP -
SN - 1943-5533
KW - Viscoelastic (VE) material
KW - Performance tests
KW - Energy dissipation mechanism
KW - Hydrogen bonds
KW - Mathematical model
ER -
TY - JOUR
TI - No ball milling nee de d: Alternative ODS steel manufacturing with gas atomization reaction synthesis (GARS) and friction-based processing
AU - Zhang, D.
AU - Darsell, J. T.
AU - Wang, J.
AU - Ma, X.
AU - Grant, G. J.
AU - Anderson, I. E.
AU - Rieken, J. R.
AU - Edwards, D. J.
AU - Setyawan, W.
AU - Horn, T. J.
AU - Odette, G. R.
T2 - JOURNAL OF NUCLEAR MATERIALS
AB - Oxide dispersion strengthened (ODS) steels are promising structural materials for future fusion reactors. The high-density (∼1023/m3) of highly stable Y-(Ti)-O nano-oxides provide high sink strength for radiation resistance and high-temperature (> 650 °C) creep strength. Concomitantly, helium management is enabled by trapping high density (∼1023/m3) of small (< 3 nm) helium bubbles in the vicinity of nano-oxides. However, conventional route of making ODS steels involves prolonged ball milling, canning, degassing, and laborious thermo-mechanical processing (TMP). Such route, especially the batch-by-batch ball milling step, faces persistent challenge with scalability and high costs. Gas atomization reaction synthesis (GARS) method has demonstrated the potential of making precursor ODS steel powders without ball milling, but the nano-oxide density was around 1021/m3 in the final consolidated form by conventional TMP. Taking advantage of GARS precursor powder, we use friction-based processing, including friction consolidation and extrusion, to manufacture ODS steel with further improved nano-oxide characteristics. Preliminary results showed that Y/Ti/O species were intimately mixed and rapidly reacted to form nano-oxides with a number density of ∼1022/m3.
DA - 2022/8/1/
PY - 2022/8/1/
DO - 10.1016/j.jnucmat.2022.153768
VL - 566
SP -
SN - 1873-4820
KW - ODS Steel
KW - Gas Atomization Reaction Synthesis
KW - Friction Consolidation and Extrusion
KW - Electron Microscopy
KW - Atom Probe Tomography
ER -
TY - JOUR
TI - Multiscale and multiphysics FEA simulation and materials optimization for laser ultrasound transducers
AU - Liu, Sipan
AU - Kim, Howuk
AU - Huang, Wenbin
AU - Chang, Wei-Yi
AU - Jiang, Xiaoning
AU - Ryu, Jong Eun
T2 - MATERIALS TODAY COMMUNICATIONS
AB - The relationship between the nanocomposite design and the laser ultrasound transducer (LUT) characteristics was investigated through simulations in multiple scale levels for material behavior, device response, and acoustic wave propagation in media. First, the effects of the nanoparticle size and concentration on the effective properties of composites were quantitatively investigated with the finite element analysis (FEA) method. Second, the effective properties of the nanocomposite were assigned to the layer, which is modeled as a homogeneous material, in the FEA for the LUT simulating the energy conversion from the incident laser to the acoustic wave. Finally, the ultrasound propagation in the water was calculated by a theoretical wave propagation model. The FEA-based prediction was compared with the experimental data in the literature and a theoretical analysis for LUT based on Thermal-Acoustic coupling. As a result, the ultrasound waves on the transducer surface and at a distance in the water could be predicted. Based on the hierarchically integrated prediction procedure, the optimal conditions of the photoacoustic nanocomposites were investigated through the parametric study with the particle size and concentration as variables. The results guide the material designs optimized for different device characteristics, such as high pressure and broad bandwidth.
DA - 2022/6//
PY - 2022/6//
DO - 10.1016/j.mtcomm.2022.103599
VL - 31
SP -
SN - 2352-4928
UR - http://dx.doi.org/10.1016/j.mtcomm.2022.103599
KW - Polymer-matrix composites (PMCs)
KW - Finite element analysis (FEA)
KW - Multiscale modeling
KW - Acoustic emission
KW - Laser ultrasound transducer
ER -
TY - JOUR
TI - Phylogeny-guided microbiome OTU-specific association test (POST)
AU - Huang, Caizhi
AU - Callahan, Benjamin John
AU - Wu, Michael C.
AU - Holloway, Shannon T.
AU - Brochu, Hayden
AU - Lu, Wenbin
AU - Peng, Xinxia
AU - Tzeng, Jung-Ying
T2 - MICROBIOME
AB - The relationship between host conditions and microbiome profiles, typically characterized by operational taxonomic units (OTUs), contains important information about the microbial role in human health. Traditional association testing frameworks are challenged by the high dimensionality and sparsity of typical microbiome profiles. Phylogenetic information is often incorporated to address these challenges with the assumption that evolutionarily similar taxa tend to behave similarly. However, this assumption may not always be valid due to the complex effects of microbes, and phylogenetic information should be incorporated in a data-supervised fashion.In this work, we propose a local collapsing test called phylogeny-guided microbiome OTU-specific association test (POST). In POST, whether or not to borrow information and how much information to borrow from the neighboring OTUs in the phylogenetic tree are supervised by phylogenetic distance and the outcome-OTU association. POST is constructed under the kernel machine framework to accommodate complex OTU effects and extends kernel machine microbiome tests from community level to OTU level. Using simulation studies, we show that when the phylogenetic tree is informative, POST has better performance than existing OTU-level association tests. When the phylogenetic tree is not informative, POST achieves similar performance as existing methods. Finally, in real data applications on bacterial vaginosis and on preterm birth, we find that POST can identify similar or more outcome-associated OTUs that are of biological relevance compared to existing methods.Using POST, we show that adaptively leveraging the phylogenetic information can enhance the selection performance of associated microbiome features by improving the overall true-positive and false-positive detection. We developed a user friendly R package POSTm which is freely available on CRAN ( https://CRAN.R-project.org/package=POSTm ). Video Abstract.
DA - 2022/6/7/
PY - 2022/6/7/
DO - 10.1186/s40168-022-01266-3
VL - 10
IS - 1
SP -
SN - 2049-2618
KW - Association test
KW - Phylogenetic tree
KW - Kernel machine regression
ER -
TY - JOUR
TI - Modeling and Stiffness-Based Continuous Torque Control of Lightweight Quasi-Direct-Drive Knee Exoskeletons for Versatile Walking Assistance
AU - Huang, Tzu-Hao
AU - Zhang, Sainan
AU - Yu, Shuangyue
AU - MacLean, Mhairi K.
AU - Zhu, Junxi
AU - Di Lallo, Antonio
AU - Jiao, Chunhai
AU - Bulea, Thomas C.
AU - Zheng, Minghui
AU - Su, Hao
T2 - IEEE TRANSACTIONS ON ROBOTICS
AB - State-of-the-art exoskeletons are typically limited by low control bandwidth and small range stiffness of actuators which are based on high gear ratios and elastic components (e.g., series elastic actuators). Furthermore, most exoskeletons are based on discrete gait phase detection and/or discrete stiffness control resulting in discontinuous torque profiles. To fill these two gaps, we developed a portable lightweight knee exoskeleton using quasi-direct drive (QDD) actuation that provides 14 Nm torque (36.8% biological joint moment for overground walking). This paper presents 1) stiffness modeling of torque-controlled QDD exoskeletons and 2) stiffness-based continuous torque controller that estimates knee joint moment in real-time. Experimental tests found the exoskeleton had high bandwidth of stiffness control (16 Hz under 100 Nm/rad) and high torque tracking accuracy with 0.34 Nm Root Mean Square (RMS) error (6.22%) across 0-350 Nm/rad large range stiffness. The continuous controller was able to estimate knee moments accurately and smoothly for three walking speeds and their transitions. Experimental results with 8 able-bodied subjects demonstrated that our exoskeleton was able to reduce the muscle activities of all 8 measured knee and ankle muscles by 8.60%-15.22% relative to unpowered condition, and two knee flexors and one ankle plantar flexor by 1.92%-10.24% relative to baseline (no exoskeleton) condition.
DA - 2022/6//
PY - 2022/6//
DO - 10.1109/TRO.2022.3170287
VL - 38
IS - 3
SP - 1442-1459
SN - 1941-0468
KW - Knee
KW - Exoskeletons
KW - Torque
KW - Legged locomotion
KW - Actuators
KW - Biomechanics
KW - Muscles
KW - Force
KW - torque control
KW - knee exoskeleton
KW - quasi-direct-drive actuation
KW - stiffness control
ER -
TY - JOUR
TI - Integrating charge mobility, stability and stretchability within conjugated polymer films for stretchable multifunctional sensors
AU - Son, Sung Yun
AU - Lee, Giwon
AU - Wang, Hongyu
AU - Samson, Stephanie
AU - Wei, Qingshan
AU - Zhu, Yong
AU - You, Wei
T2 - NATURE COMMUNICATIONS
AB - Conjugated polymers (CPs) are promising semiconductors for intrinsically stretchable electronic devices. Ideally, such CPs should exhibit high charge mobility, excellent stability, and high stretchability. However, converging all these desirable properties in CPs has not been achieved via molecular design and/or device engineering. This work details the design, synthesis and characterization of a random polythiophene (RP-T50) containing ~50 mol% of thiophene units with a thermocleavable tertiary ester side chain and ~50 mol% of unsubstituted thiophene units, which, upon thermocleavage of alkyl chains, shows significant improvement of charge mobility and stability. Thermal annealing a RP-T50 film coated on a stretchable polydimethylsiloxane substrate spontaneously generates wrinkling in the polymer film, which effectively enhances the stretchability of the polymer film. The wrinkled RP-T50-based stretchable sensors can effectively detect humidity, ethanol, temperature and light even under 50% uniaxial and 30% biaxial strains. Our discoveries offer new design rationale of strategically applying CPs to intrinsically stretchable electronic systems.
DA - 2022/5/18/
PY - 2022/5/18/
DO - 10.1038/s41467-022-30361-0
VL - 13
IS - 1
SP -
SN - 2041-1723
ER -
TY - JOUR
TI - Numerical simulation of stable and unstable ram-mode operation of an axisymmetric ethylene-fueled inlet-isolator-combustor configuration
AU - Hash, Caleb A.
AU - Drummond, Paige M.
AU - Edwards, Jack R.
AU - Kato, Nozomu
AU - Lee, Tonghun
T2 - COMBUSTION AND FLAME
AB - Large-eddy simulations of stable and unstable ramjet operational modes are presented for an axisymmetric inlet-isolator-combustor configuration experimentally tested in the University of Illinois's ACT-II arc-heated combustion tunnel. A 32 species ethylene oxidation mechanism including nitrous oxide formation reactions is used in the calculations (HyChem FFCM 2.0). Conjugate heat-transfer models based on an assumed penetration depth of the applied heating load are used to account for localized wall heating during the short durations (∼0.2 to 0.3 s) of the parts of the experiments simulated in this work. The results show a marked sensitivity to trace levels of atomic oxygen (∼1% by mass) in the free stream, a consequence of the arc-heating process. Atomic oxygen significantly reduces ignition delay at the relatively low pressures present within the configuration. With 1% atomic oxygen in the free stream, a jet-wake stabilized, partially-premixed flame structure emerges during thermal-throat ramjet operation at an equivalence ratio of 1.24, in accord with available experimental pressure and imaging measurements. Considering the free stream as pure air results in a cavity-wake stabilized, rich premixed flame. Simulations of unstable ram-mode operation leading to inlet unstart at an equivalence ratio of 1.97 also indicate a sensitivity to the free-stream composition. A reduction in atomic oxygen concentration to 0.8% by mass yields good agreement with the experimentally-observed isolator shock-train propagation speed. Both the computational and experimental results indicate that the shock train accelerates before being disgorged from the inlet. This acceleration stems from a rapid increase in the sizes of regions of low speed, sometimes separated flow behind Mach disks that form as the shock train proceeds upstream.
DA - 2022/8//
PY - 2022/8//
DO - 10.1016/j.combustflame.2022.112157
VL - 242
SP -
SN - 1556-2921
KW - Large eddy simulation
KW - Partially-premixed combustion
KW - Isolator shock train
KW - Thermal-throat ramjet
ER -
TY - JOUR
TI - Prediction of pore-scale-property dependent natural convection in porous media at high Rayleigh numbers
AU - Gasow, Stefan
AU - Kuznetsov, Andrey V.
AU - Jin, Yan
T2 - INTERNATIONAL JOURNAL OF THERMAL SCIENCES
AB - Natural convection in porous media has received increasing attention in recent years due to its significance in engineering applications. This process is traditionally analyzed by the solution of the classical Darcy-Oberbeck-Boussinesq (DOB) equations. According to the DOB equations, natural convection in porous media is exclusively dependent on the Rayleigh-Darcy number, Ra, while the Sherwood number, Sh, has a linear relationship with Ra at high Rayleigh numbers. However, these predictions conflict with experimental observations. In this study, we have performed a pore-scale resolved direct numerical simulation (DNS) study of natural convection in periodic porous media composed of two-dimensional square and circular obstacles. Based on our analysis, a new correlation of Sh for large Rayleigh numbers (Ra≥1000), low Darcy numbers Da, and high Schmidt numbers Sc (Da/Sc≤2×10−8) has been proposed, expressed as Sh=aRa1−0.2φ2+1, where a=0.011±0.002 is a pore-scale geometric parameter. The new correlation has been validated over a wide range of Rayleigh numbers, porosity values, and pore-scale geometries. Our DNS results also show that, with a decrease of porosity, it becomes more difficult for mega-plumes with low wavenumbers to enter the boundary layer. Low wavenumber motions decay much faster with a decrease of Da than the pore-scale motions near the wall. The volume-averaged dissipation rate nondimensionalized using the pore size εˆi has the scaling law εˆi∼Da in the internal region and εˆi∼Da1/2 in the near-wall region. We expect that these characteristics obtained from DNS also apply to natural convection in porous media with much lower Darcy numbers.
DA - 2022/9//
PY - 2022/9//
DO - 10.1016/j.ijthermalsci.2022.107635
VL - 179
SP -
SN - 1778-4166
KW - Porous media
KW - Natural convection
KW - Mass transfer
KW - Direct numerical simulation
KW - Macroscopic modeling
ER -
TY - JOUR
TI - On-Demand Solar and Thermal RadiationManagement Based on Switchable Interwoven Surfaces
AU - Ke, Yujie
AU - Li, Yanbin
AU - Wu, Lichen
AU - Wang, Shancheng
AU - Yang, Ronggui
AU - Yin, Jie
AU - Tan, Gang
AU - Long, Yi
T2 - ACS ENERGY LETTERS
AB - On-demand and selective regulation of the radiative cooling (long-wave infrared, LWIR) and solar heat gain (ultraviolet-, visible- and near-IR, UV–vis–NIR) of building facades is a grand challenge but essential to decrease energy usage in buildings. Here, we report a reconfigurable interwoven surface that can dynamically switch the overlapping sequence to achieve spectral selectivity and ultrabroadband modulations for windows, walls/roofs with decent spectral modulations, and energy-saving performance. The result surpasses the best reported passive radiative cooling smart windows with a more than doubled visible transmittance (Tlum = 0.50) and LWIR modulation (Δ εLWIR = 0.57). Our energy-saving samples outperform the commercial building materials across climate zones 2–6. This design principle is scalable and applicable for diverse materials, interwoven structures, and 2D-3D surfaces, which provide a strategy to give programmable heating/cooling modulations in various applications.
DA - 2022/5/13/
PY - 2022/5/13/
DO - 10.1021/acsenergylett.2c00419
VL - 7
IS - 5
SP - 1758-1763
SN - 2380-8195
ER -
TY - JOUR
TI - Estimation of Thickness and Speed of Sound for Transverse Cortical Bone Imaging Using Phase Aberration Correction Methods: An In Silico and Ex Vivo Validation Study
AU - Minh, Huong Nguyen
AU - Muller, Marie
AU - Raum, Kay
T2 - APPLIED SCIENCES-BASEL
AB - Delay-and-sum (DAS) beamforming of backscattered echoes is used for conventional ultrasound imaging. Although DAS beamforming is well suited for imaging in soft tissues, refraction, scattering, and absorption, porous mineralized tissues cause phase aberrations of reflected echoes and subsequent image degradation. The recently developed refraction corrected multi-focus technique uses subsequent focusing of waves at variable depths, the tracking of travel times of waves reflected from outer and inner cortical bone interfaces, the estimation of the shift needed to focus from one interface to another to determine cortical thickness (Ct.Th), and the speed of sound propagating in a radial bone direction (Ct.ν11). The method was validated previously in silico and ex vivo on plate shaped samples. The aim of this study was to correct phase aberration caused by bone geometry (i.e., curvature and tilt with respect to the transducer array) and intracortical pores for the multi-focus approach. The phase aberration correction methods are based on time delay estimation via bone geometry differences to flat bone plates and via the autocorrelation and cross correlation of the reflected ultrasound waves from the endosteal bone interface. We evaluate the multi-focus approach by incorporating the phase aberration correction methods by numerical simulation and one experiment on a human tibia bone, and analyze the precision and accuracy of measuring Ct.Th and Ct.ν11. Site-matched reference values of the cortical thickness of the human tibia bone were obtained from high-resolution peripheral computed tomography. The phase aberration correction methods resulted in a more precise (coefficient of variation of 5.7%) and accurate (root mean square error of 6.3%) estimation of Ct.Th, and a more precise (9.8%) and accurate (3.4%) Ct.ν11 estimation, than without any phase aberration correction. The developed multi-focus method including phase aberration corrections provides local estimations of both cortical thickness and sound velocity and is proposed as a biomarker of cortical bone quality with high clinical potential for the prevention of osteoporotic fractures.
DA - 2022/5//
PY - 2022/5//
DO - 10.3390/app12105283
VL - 12
IS - 10
SP -
SN - 2076-3417
KW - medical beamforming
KW - phase aberration correction
KW - medical tissue characterization
KW - pulse-echo ultrasound
KW - medical signal and image processing
ER -
TY - JOUR
TI - Advanced controller synthesis for fuzzy parameter varying systems
AU - Ban, Xiaojun
AU - Zhang, Hongyang
AU - Wu, Fen
T2 - JOURNAL OF THE FRANKLIN INSTITUTE-ENGINEERING AND APPLIED MATHEMATICS
AB - A novel nonlinear time-varying model termed as the fuzzy parameter varying (FPV) system is proposed in this research, which inherits both advantages of the conventional T-S fuzzy system in dealing with nonlinear plants and strengths of the linear parameter varying (LPV) system in handling time-varying features. It is, therefore, an attractive mathematical model to efficiently approximate a nonlinear time-varying plant or to serve as a type of time-varying controller. Using the full block S-procedure, sufficient stability conditions have been derived in the form of linear matrix inequalities (LMIs) to test quadratic stability of the open-loop FPV system. Moreover, sufficient conditions have been derived on synthesizing both state feedback and dynamical output feedback fuzzy gain-scheduling controllers that can stabilize the FPV system. An inverted pendulum with a variable length pole is utilized to demonstrate advantages of the FPV system compared to the conventional T-S fuzzy system in representing a practical time-varying nonlinear plant and to validate the controller synthesis conditions.
DA - 2022/1//
PY - 2022/1//
DO - 10.1016/j.jfranklin.2020.12.038
VL - 359
IS - 2
SP - 762-785
SN - 1879-2693
ER -
TY - JOUR
TI - Effect of Spanwise Hole-to-Hole Spacing on Overall Cooling Effectiveness of Effusion Cooled Combustor Liners for a Swirl-Stabilized Can Combustor
AU - Ahmed, Shoaib
AU - Wahls, Benjamin H.
AU - Ekkad, Srinath V.
AU - Lee, Hanjie
AU - Ho, Yin-Hsiang
T2 - Journal of Turbomachinery
AB - Abstract One of the most effective ways to cool the combustor liner is through effusion cooling. Effusion cooling (also known as full-coverage effusion cooling) involves uniformly spaced holes distributed throughout the combustor liner wall. Effusion cooling configurations are preferred for their high effectiveness, low-pressure penalty, and ease of manufacturing. In this article, experimental results are presented for effusion cooling configurations for a realistic swirl driven can combustor under reacting (flame) conditions. The can combustor was equipped with an industrial engine swirler and gaseous fuel (methane), subjecting the liner walls to engine representative flow and combustion conditions. In this study, three different effusion cooling liners with spanwise spacings of r/d = 6, 8, and 10 and streamwise spacing of z/d = 10 were tested for four coolant-to-main airflow ratios. The experiments were carried out at a constant main flow Reynolds number (based on combustor diameter) of 12,500 at a total equivalence ratio of 0.65. Infrared thermography (IRT) was used to measure the liner outer surface temperature, and detailed overall effectiveness values were determined under steady-state conditions. The results indicate that decreasing the spanwise hole-to-hole spacing (r/d) from ten to eight increased the overall cooling effectiveness by 2–5%. It was found that reducing the spanwise hole-to-hole spacing further to r/d = 6 does not affect the cooling effectiveness implying the existence of an optimum spanwise hole-to-hole spacing. Also, the minimum liner cooling effectiveness on the liner wall was found to be downstream of the impingement location, which is not observed in the existing literature for experiments done under nonreacting conditions.
DA - 2022/5/27/
PY - 2022/5/27/
DO - 10.1115/1.4054442
VL - 144
IS - 7
SP -
LA - en
OP -
SN - 0889-504X 1528-8900
UR - http://dx.doi.org/10.1115/1.4054442
DB - Crossref
KW - heat transfer
KW - effusion cooling
KW - combustion
KW - fluid dynamics and heat transfer phenomena in compressor and turbine components of gas turbine engines
KW - heat transfer and film cooling
ER -
TY - JOUR
TI - The Ever-Growing Field of High-Frequency Biomedical Ultrasound
AU - Cloutier, Guy
AU - Levassort, Franck
AU - Jiang, Xiaoning
AU - Zhou, Qifa
T2 - IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL
AB - Compared with other medical imaging counterparts, ultrasound has advantages owing to its real-time imaging capability, easy access, and cost-effectiveness. High-frequency (>20 MHz) ultrasound has been developed over the last few decades and is attractive because it provides high-resolution medical imaging and ultrasound backscattering microscopy (UBM) measurements, with applications targeting small animal imaging and some areas of human diagnosis. In recent years, driven by growing needs in intravascular ultrasound (IVUS) imaging, minimally invasive surgery, and particle manipulation, high-frequency ultrasound has continued to flourish as a niche modality and has expanded its important role in both diagnostic imaging and therapy. Concomitant needs have thus arisen in technological research and development to innovate materials, devices, algorithms, and systems for a variety of high-frequency ultrasound applications in medicine and biology.
DA - 2022/6//
PY - 2022/6//
DO - 10.1109/TUFFC.2022.3174370
VL - 69
IS - 6
SP - 1845-1847
SN - 1525-8955
ER -
TY - JOUR
TI - Ultrasound-Guided Intravascular Sonothrombolysis With a Dual Mode Ultrasound Catheter: In Vitro Study
AU - Wu, Huaiyu
AU - Zhang, Bohua
AU - Huang, Chih-Chung
AU - Peng, Chang
AU - Zhou, Qifa
AU - Jiang, Xiaoning
T2 - IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL
AB - Thromboembolism in vessels often leads to stroke or heart attack and even sudden death unless brought under control. Sonothrombolysis based on ultrasound contrast agents has shown promising outcome in effective treatment of thromboembolism. Intravascular sonothrombolysis transducer was reported recently for unprecedented sonothrombolysis in vitro. However, it is necessary to provide an imaging guide during thrombolysis in clinical applications for optimal treatment efficiency. In this article, a dual mode ultrasound catheter was developed by combining a 16-MHz high-frequency element (imaging transducer) and a 220-kHz low-frequency element (treatment transducer) for sonothrombolysis in vitro. The treatment transducer was designed with a 20-layer PZT-5A stack with the aperture size of 1.2×1.2 mm2, and the imaging transducer with the aperture size of 1.2×1.2 mm2 was attached in front of the treatment transducer. Both transducers were assembled into a customized 2-lm 10-Fr catheter. In vitro experiment was carried out using a bovine blood clot. Imaging tests were conducted, showing that the backscattering signals can be obtained with a high signal-to-noise ratio (SNR) for the 16-MHz imaging transducer. Sonothrombolysis was performed successfully that the volume of clot was reduced significantly after the 30-min treatment. The size changes of clot were observed clearly using the 16-MHz M-mode imaging during the thrombolysis. The findings suggest that the proposed ultrasound-guided intravascular sonothrombolysis can be enhanced since the position of treatment transducer can be adjusted with the target at the clot due to the imaging guide.
DA - 2022/6//
PY - 2022/6//
DO - 10.1109/TUFFC.2022.3153929
VL - 69
IS - 6
SP - 1917-1925
SN - 1525-8955
KW - Imaging-guided sonothombolysis
KW - intravascular ultrasound transducer
KW - ultrasound imaging
ER -
TY - JOUR
TI - Discrete element method simulator for joint dynamics: a case study using a red-tailed hawk's hallux digit
AU - Mollik, Tushar
AU - Kennedy, Scott
AU - Ul Shougat, Md Raf E.
AU - Li, Xiaofu
AU - Fitzgerald, Timothy
AU - Echols, Scott
AU - Kirk, Nick
AU - Silverberg, Larry
AU - Perkins, Edmon
T2 - MULTIBODY SYSTEM DYNAMICS
DA - 2022/6/2/
PY - 2022/6/2/
DO - 10.1007/s11044-022-09828-x
VL - 6
SP -
SN - 1573-272X
KW - Discrete element method
KW - Dynamic simulation
KW - Multibody
KW - Biomechanical analysis
KW - Skeletal system
ER -
TY - JOUR
TI - An analytical solution simulating growth of Lewy bodies
AU - Kuznetsov, Ivan A.
AU - Kuznetsov, Andrey V
T2 - MATHEMATICAL MEDICINE AND BIOLOGY-A JOURNAL OF THE IMA
AB - This paper reports a minimal model simulating the growth of a Lewy body (LB). To the best of our knowledge, this is the first model simulating LB growth. The LB is assumed to consist of a central spherical core, which is composed of membrane fragments and various dysfunctional intracellular organelles, and a halo, which is composed of alpha-synuclein (α-syn) fibrils. Membrane fragments and α-syn monomers are assumed to be produced in the soma at constant rates. The growth of the core and the halo are simulated by the Finke-Watzky model. Analytical (closed-form) solutions describing the growth of the core and the halo are obtained. A sensitivity analysis in terms of model parameters is performed.
DA - 2022/6/2/
PY - 2022/6/2/
DO - 10.1093/imammb/dqac006
SP -
SN - 1477-8602
KW - alpha-synuclein
KW - mathematical modelling
KW - Lewy body dementia
KW - Parkinson's disease
KW - neuron
ER -
TY - JOUR
TI - Principal component analysis based combustion model in the context of a lifted methane/air flame: Sensitivity to the manifold parameters and subgrid closure
AU - Malik, Mohammad Rafi
AU - Coussement, Axel
AU - Echekki, Tarek
AU - Parente, Alessandro
T2 - COMBUSTION AND FLAME
AB - The present work advances the PC-transport approach in the context of Large Eddy Simulation (LES) of turbulent combustion. Accurate modeling of combustion systems requires large kinetic mechanisms. However, realistic high-fidelity simulations of turbulent reacting flows still represent a big challenge on the current computational tools. Therefore, a parameterization of the thermo-chemical state-space using a reduced number of variables is needed. To this end, the potential offered by Principal Component Analysis (PCA) in identifying low-dimensional manifolds is very appealing. The present paper extends the PC-transport approach, coupled with Gaussian Process Regression (GPR), to a lifted methane/air flame in LES. Previous investigations by the authors showed the great potential of the PC-GPR model in the context of Sandia flames. This study investigated some key features of the model: the sensitivity to the training data set and the scaling methods . To this end, two different canonical reactors were used: unsteady counter-flow laminar flames (CFLF) and unsteady perfectly stirred reactor (PSR). Moreover, the authors proposes an approach to address the issue of data density inherent to large numerical data sets, by means of a kernel density weighting of the data set before applying PCA. Finally, a subgrid scale (SGS) closure model was coupled to the PC-transport approach to treat complex turbulence/chemistry interactions.
DA - 2022/10//
PY - 2022/10//
DO - 10.1016/j.combustflame.2022.112134
VL - 244
SP -
SN - 1556-2921
UR - https://doi.org/10.1016/j.combustflame.2022.112134
KW - Turbulent combustion
KW - Principal component analysis
KW - Nonlinear regression
KW - Large eddy simulation
KW - Auto-ignition
KW - Low-dimensional manifolds
ER -
TY - JOUR
TI - Fault Estimation Observer Design for Markovian Jump Systems With Nondifferentiable Actuator and Sensor Failures
AU - Chen, Liheng
AU - Zhu, Yanzheng
AU - Wu, Fen
AU - Zhao, Yuxin
T2 - IEEE TRANSACTIONS ON CYBERNETICS
AB - This article addresses the simultaneous actuator and sensor fault estimation (FE) problem for a class of Markovian jump systems (MJSs) with nondifferentiable actuator failures. In order to overcome the difficulties brought by the nondifferentiable actuator failures, we construct an extended vector composed of states, sensor faults, and disturbances, where the derivatives of actuator failures are not required in this augmented system. Then, two novel observer-based approaches are developed for the augmented descriptor system to cope with the FE problem. The first one is a reduced-order FE observer, where the actuator failures can be estimated by the algebraic input reconstruction strategy. The second one refers to an iterative learning observer (ILO) design method, which can obtain the accurate FE result by integrating the estimations in the iterative processes. The two proposed FE observer design methods can avoid the sliding surface switching problem produced by sliding-mode observers in the area of MJSs. Finally, a practical example of the F-404 aircraft engine system is presented to show the validity of the proposed FE observer design techniques.
DA - 2022/5/13/
PY - 2022/5/13/
DO - 10.1109/TCYB.2022.3169290
SP -
SN - 2168-2275
KW - Iron
KW - Observers
KW - Actuators
KW - Estimation
KW - Switches
KW - Markov processes
KW - Trajectory
KW - Fault detection
KW - fault estimation (FE)
KW - iterative learning observer (ILO)
KW - Markovian jump systems (MJSs)
ER -
TY - JOUR
TI - The evolution of turbulent micro-vortices and their effect on convection heat transfer in porous media
AU - Huang, Ching-Wei
AU - Srikanth, Vishal
AU - Kuznetsov, Andrey V
T2 - JOURNAL OF FLUID MECHANICS
AB - New insight into the contribution of the microscale vortex evolution to convection heat transfer in porous media is presented in this paper. The objective is to determine how the microscale vortices influence convection heat transfer in turbulent flow inside porous media. The microscale temperature distribution is analysed using flow visualization in two dimensions using streamlines and in three dimensions using the Q -criterion. The pertinent observations are supplemented with a comparison of surface skin friction and heat transfer using: (i) surface skin-friction lines and (ii) the joint probability density function of the pressure and skin-friction coefficients, along with the Nusselt number. The microscale flow phenomena observed are corroborated with the features of the frequency spectra of the drag coefficient and macroscale Nusselt number. The large eddy simulation technique is used in this study to investigate the flow field inside a periodic porous medium. The Reynolds numbers of the flow are 300 and 500. The porous medium consists of solid obstacles in the shape of square and circular cylinders. Two distinct flow regimes are represented by using the porosities of 0.50 and 0.87. The results show that the surface Nusselt number distribution is dependent on whether the micro-vortices are attached to or detached from the surface of the obstacle. The spectra of the macroscale Nusselt number and the pressure drag are similar, signifying a correlation between the dynamics of heat transfer and the microscale turbulent structures. Both vortex shedding and secondary flow instabilities are observed that significantly influence the Nusselt number. The fundamental insight gained in this paper can inform the development of more robust macroscale models of convection heat transfer in turbulent flow in porous media.
DA - 2022/5/18/
PY - 2022/5/18/
DO - 10.1017/jfm.2022.291
VL - 942
SP -
SN - 1469-7645
KW - vortex instability
KW - convection in porous media
KW - turbulence simulation
ER -
TY - JOUR
TI - Autonomous Closed-Loop Experimental Characterization and Dynamic Model Validation of a Scaled Underwater Kite
AU - Abney, Andrew
AU - Reed, James
AU - Naik, Kartik
AU - Bryant, Samuel
AU - Herbert, Dillon
AU - Leonard, Zak
AU - Vadlamannati, Ashwin
AU - Mook, Mariah
AU - Beknalkar, Sumedh
AU - Alvarez, Miguel
AU - Granlund, Kenneth
AU - Bryant, Matthew
AU - Mazzoleni, Andre
AU - Fathy, Hosam
AU - Vermillion, Chris
T2 - JOURNAL OF DYNAMIC SYSTEMS MEASUREMENT AND CONTROL-TRANSACTIONS OF THE ASME
AB - Abstract This paper presents the closed-loop experimental framework and dynamic model validation for a 1/12-scale underwater kite design. The pool-based tow testing framework described herein, which involves a fully actuated, closed-loop controlled kite and flexible tether, significantly expands upon the capabilities of any previously developed open-source framework for experimental underwater kite characterization. Specifically, the framework has allowed for the validation of three closed-loop flight control strategies, along with a critical comparison between dynamic model predictions and experimental results. In this paper, we provide a detailed presentation of the experimental tow system and kite setup, describe the control algorithms implemented and tested, and quantify the level of agreement between our multi-degree-of-freedom kite dynamic model and experimental data. We also present a sensitivity analysis that helps to identify the most influential parameters to kite performance and further explain the remaining mismatches between the model and data.
DA - 2022/7/1/
PY - 2022/7/1/
DO - 10.1115/1.4054141
VL - 144
IS - 7
SP -
SN - 1528-9028
ER -
TY - JOUR
TI - Design of a Bio-Inspired Gait Phase Decoder Based on Temporal Convolution Network Architecture With Contralateral Surface Electromyography Toward Hip Prosthesis Control
AU - Chen, Yixi
AU - Li, Xinwei
AU - Su, Hao
AU - Zhang, Dingguo
AU - Yu, Hongliu
T2 - FRONTIERS IN NEUROROBOTICS
AB - Inter-leg coordination is of great importance to guarantee the safety of the prostheses wearers, especially for the subjects at high amputation levels. The mainstream of current controllers for lower-limb prostheses is based on the next motion state estimation by the past motion signals at the prosthetic side, which lacks immediate responses and increases falling risks. A bio-inspired gait pattern generation architecture was proposed to provide a possible solution to the bilateral coordination issue. The artificial movement pattern generator (MPG) based on the temporal convolution network, fusing with the motion intention decoded from the surface electromyography (sEMG) measured at the impaired leg and the motion status from the kinematic modality of the prosthetic leg, can predict four sub gait phases. Experiment results suggested that the gait phase decoder exhibited a relatively high intra-subject consistency in the gait phase inference, adapted to various walking speeds with mean decoding accuracy ranging from 89.27 to 91.16% across subjects, and achieved an accuracy of 90.30% in estimating the gait phase of the prosthetic leg in the hip disarticulation amputee at the self-selected pace. With the proof of concept and the offline experiment results, the proposed architecture improves the walking coordination with prostheses for the amputees at hip level amputation.
DA - 2022/5/9/
PY - 2022/5/9/
DO - 10.3389/fnbot.2022.791169
VL - 16
SP -
SN - 1662-5218
KW - gait phase
KW - gait coordination
KW - lower limb prosthesis
KW - sensor fusion
KW - sEMG
KW - temporal convolution network
KW - detrended cross-correlation analysis (DCCA)
KW - hip disarticulation
ER -
TY - JOUR
TI - Demonstration of Coherent Interference between Acoustic Waves Using a Fiber Ring Resonator
AU - Kim, Jee Myung
AU - Wee, Junghyun
AU - Peters, Kara
T2 - SENSORS
AB - Optical fibers were previously demonstrated to propagate and detect acoustic modes that were converted from Lamb waves for structural health-monitoring applications; typically, a fiber Bragg grating sensor in the optical fiber is used to detect acoustic modes. Acoustic modes can transfer from one fiber to another through a simple adhesive bond coupler, preserving the waveform of the acoustic mode. This paper experimentally investigates the coherence of acoustic waves through the adhesive coupler, using a fiber ring resonator (FRR) configuration. This configuration was chosen because the wave coupled to the second fiber interferes with the original wave after it encircles the fiber ring. We performed this experiment using different geometries of optical fibers in the ring, including a standard single-mode optical fiber, a hollow silica capillary tube, and a large-diameter multi-mode fiber. The results demonstrate that the acoustic wave, when transferring through an adhesive coupler, interferes coherently even when the main and ring fibers are of different types. Finally, we demonstrate that the FRR can be applied for sensing applications by measuring the mode attenuations in the ring due to a changing external environment (water-level sensing) and measuring the optical-path length change in the ring (temperature sensing).
DA - 2022/6//
PY - 2022/6//
DO - 10.3390/s22114163
VL - 22
IS - 11
SP -
SN - 1424-8220
UR - https://www.mdpi.com/1424-8220/22/11/4163
KW - structural health monitoring
KW - optical fiber
KW - acoustic coupling
KW - coherent interference
KW - fiber ring resonator
ER -
TY - JOUR
TI - Ultrasoft Porous 3D Conductive Dry Electrodes for Electrophysiological Sensing and Myoelectric Control
AU - Yao, Shanshan
AU - Zhou, Weixin
AU - Hinson, Robert
AU - Dong, Penghao
AU - Wu, Shuang
AU - Ives, Jasmine
AU - Hu, Xiaogang
AU - Huang, He
AU - Zhu, Yong
T2 - ADVANCED MATERIALS TECHNOLOGIES
AB - Abstract Biopotential electrodes have found broad applications in health monitoring, human–machine interactions, and rehabilitation. This article reports the fabrication and applications of ultrasoft breathable dry electrodes that can address several challenges for their long‐term wearable applications—skin compatibility, wearability, and long‐term stability. The proposed electrodes rely on porous and conductive silver nanowire‐based nanocomposites as the robust mechanical and electrical interface. The highly conductive and conformable structure eliminates the necessity of conductive gel while establishing a sufficiently low electrode–skin impedance for high‐fidelity electrophysiological sensing. The introduction of gas‐permeable structures via a simple and scalable method based on sacrificial templates improves breathability and skin compatibility for applications requiring long‐term skin contact. Such conformable and breathable dry electrodes allow for efficient and unobtrusive monitoring of heart, muscle, and brain activities. In addition, based on the muscle activities captured by the electrodes and a musculoskeletal model, electromyogram‐based neural–machine interfaces are realized, illustrating the great potential for prosthesis control, neurorehabilitation, and virtual reality.
DA - 2022/5/16/
PY - 2022/5/16/
DO - 10.1002/admt.202101637
SP -
SN - 2365-709X
KW - biopotential
KW - dry electrodes
KW - electrocardiogram
KW - electroencephalogram
KW - electromyogram
KW - nanomaterials
ER -
TY - JOUR
TI - Dynamic effects on reservoir computing with a Hopf oscillator
AU - Ul Shougat, Md Raf E.
AU - Li, XiaoFu
AU - Perkins, Edmon
T2 - PHYSICAL REVIEW E
AB - Limit cycle oscillators have the potential to be resourced as reservoir computers due to their rich dynamics. Here, a Hopf oscillator is used as a physical reservoir computer by discarding the delay line and time-multiplexing procedure. A parametric study is used to uncover computational limits imposed by the dynamics of the oscillator using parity and chaotic time-series prediction benchmark tasks. Resonance, frequency ratios from the Farey sequence, and Arnold tongues were found to strongly affect the computation ability of the reservoir. These results provide insights into fabricating physical reservoir computers from limit cycle systems.
DA - 2022/4/25/
PY - 2022/4/25/
DO - 10.1103/PhysRevE.105.044212
VL - 105
IS - 4
SP -
SN - 2470-0053
ER -
TY - JOUR
TI - Leading-edge-vortex tailoring on unsteady airfoils using an inverse aerodynamic approach
AU - Suresh Babu, Arun Vishnu
AU - Narsipur, Shreyas
AU - Bryant, Matthew
AU - Gopalarathnam, Ashok
T2 - PHYSICS OF FLUIDS
AB - In this paper, we present an approach to obtain a desired leading-edge vortex (LEV) shedding pattern from unsteady airfoils through the execution of suitable motion kinematics. Previous research revealed that LEV shedding is associated with the leading-edge suction parameter (LESP) exceeding a maximum threshold. A low-order method called LESP-modulated discrete vortex method (LDVM) was also developed to predict the onset and termination of LEV shedding from an airfoil undergoing prescribed motion kinematics. In the current work, we present an inverse-aerodynamic formulation based on the LDVM to generate the appropriate motion kinematics to achieve a prescribed LESP variation, and thus, the desired LEV shedding characteristics from the airfoil. The algorithm identifies the kinematic state of the airfoil required to attain the target LESP value through an iterative procedure performed inside the LDVM simulation at each time step. Several case studies are presented to demonstrate design scenarios such as tailoring the duration and intensity of LEV shedding, inducing LEV shedding from the chosen surface of the airfoil, promoting or suppressing LEV shedding during an unsteady motion on demand, and achieving similar LEV shedding patterns using different maneuvers. The kinematic profiles generated by the low-order formulation are also simulated using a high-fidelity unsteady Reynolds-averaged Navier–Stokes method to confirm the accuracy of the low-order model.
DA - 2022/5//
PY - 2022/5//
DO - 10.1063/5.0090328
VL - 34
IS - 5
SP -
SN - 1089-7666
ER -
TY - JOUR
TI - Effect of Rotation on Heat Transfer in AR = 2:1 and AR = 4:1 Channels Connected by a Series of Crossover Jets
AU - Madhavan, Srivatsan
AU - Singh, Prashant
AU - Ekkad, Srinath
T2 - Journal of Turbomachinery
AB - Abstract Detailed heat transfer measurements using transient liquid crystal thermography were performed on a novel cooling design covering the mid-chord and trailing edge region of a typical gas turbine blade under stationary and rotating conditions. The test section comprised two channels with aspect ratio (AR) of 2:1 (mid-chord) and 4:1 (trailing edge), where the coolant was fed into the AR = 2:1 channel from the root. Rib turbulators with a pitch-to-rib height ratio (p/e) of 10 and rib height-to-channel hydraulic diameter ratio (e/Dh) of 0.075 were placed in the AR = 2:1 channel at an angle of 60 deg relative to the direction of flow. The coolant after entering this section was routed to the AR = 4:1 section through a set of crossover jets. The purpose of the crossover jets was to induce sideways impingement onto the pin fins that were placed in the 4:1 section to enhance heat transfer. The 4:1 section had a realistic trapezoidal shape that mimics the trailing edge of an actual gas turbine blade. The pin fins were arranged in a staggered array with a center-to-center spacing of 2.5 times the pin diameter in both spanwise and streamwise directions. The trailing edge section consisted of both radial and cutback exit holes for flow exit. Experiments were performed for the Reynolds number (Redh(AR=2:1)) of 20,000 at Rotation numbers (Rodh(AR=2:1)) of 0, 0.1, and 0.14. The channel-averaged heat transfer coefficient on trailing side was ∼28% (AR = 2:1) and ∼7.6% (AR = 4:1) higher than the leading side for Rotation number (Ro) of 0.1. It is shown that the combination of crossover jets and pin fins can be an effective method for cooling wedge-shaped trailing edge channels over axial cooling flow designs.
DA - 2022/2/24/
PY - 2022/2/24/
DO - 10.1115/1.4053237
VL - 144
IS - 6
SP -
LA - en
OP -
SN - 0889-504X 1528-8900
UR - http://dx.doi.org/10.1115/1.4053237
DB - Crossref
KW - measurement techniques
KW - turbine blade and measurement advancements
ER -
TY - JOUR
TI - Evaluating machine learning classifiers for glaucoma referral decision support in primary care settings
AU - Kaskar, Omkar G.
AU - Wells-Gray, Elaine
AU - Fleischman, David
AU - Grace, Landon
T2 - SCIENTIFIC REPORTS
AB - Several artificial intelligence algorithms have been proposed to help diagnose glaucoma by analyzing the functional and/or structural changes in the eye. These algorithms require carefully curated datasets with access to ocular images. In the current study, we have modeled and evaluated classifiers to predict self-reported glaucoma using a single, easily obtained ocular feature (intraocular pressure (IOP)) and non-ocular features (age, gender, race, body mass index, systolic and diastolic blood pressure, and comorbidities). The classifiers were trained on publicly available data of 3015 subjects without a glaucoma diagnosis at the time of enrollment. 337 subjects subsequently self-reported a glaucoma diagnosis in a span of 1-12 years after enrollment. The classifiers were evaluated on the ability to identify these subjects by only using their features recorded at the time of enrollment. Support vector machine, logistic regression, and adaptive boosting performed similarly on the dataset with F1 scores of 0.31, 0.30, and 0.28, respectively. Logistic regression had the highest sensitivity at 60% with a specificity of 69%. Predictive classifiers using primarily non-ocular features have the potential to be used for identifying suspected glaucoma in non-eye care settings, including primary care. Further research into finding additional features that improve the performance of predictive classifiers is warranted.
DA - 2022/5/20/
PY - 2022/5/20/
DO - 10.1038/s41598-022-12270-w
VL - 12
IS - 1
SP -
SN - 2045-2322
ER -
TY - JOUR
TI - State of the Art and Future Opportunities in MRI-Guided Robot-Assisted Surgery and Interventions
AU - Su, Hao
AU - Kwok, Ka-Wai
AU - Cleary, Kevin
AU - Iordachita, Iulian
AU - Cavusoglu, M. Cenk
AU - Desai, Jaydev P.
AU - Fischer, Gregory S.
T2 - PROCEEDINGS OF THE IEEE
AB - Magnetic resonance imaging (MRI) can provide high-quality 3-D visualization of target anatomy, surrounding tissue, and instrumentation, but there are significant challenges in harnessing it for effectively guiding interventional procedures. Challenges include the strong static magnetic field, rapidly switching magnetic field gradients, high-power radio frequency pulses, sensitivity to electrical noise, and constrained space to operate within the bore of the scanner. MRI has a number of advantages over other medical imaging modalities, including no ionizing radiation, excellent soft-tissue contrast that allows for visualization of tumors and other features that are not readily visible by other modalities, true 3-D imaging capabilities, including the ability to image arbitrary scan plane geometry or perform volumetric imaging, and capability for multimodality sensing, including diffusion, dynamic contrast, blood flow, blood oxygenation, temperature, and tracking of biomarkers. The use of robotic assistants within the MRI bore, alongside the patient during imaging, enables intraoperative MR imaging (iMRI) to guide a surgical intervention in a closed-loop fashion that can include tracking of tissue deformation and target motion, localization of instrumentation, and monitoring of therapy delivery. With the ever-expanding clinical use of MRI, MRI-compatible robotic systems have been heralded as a new approach to assist interventional procedures to allow physicians to treat patients more accurately and effectively. Deploying robotic systems inside the bore synergizes the visual capability of MRI and the manipulation capability of robotic assistance, resulting in a closed-loop surgery architecture. This article details the challenges and history of robotic systems intended to operate in an MRI environment and outlines promising clinical applications and associated state-of-the-art MRI-compatible robotic systems and technology for making this possible.
DA - 2022/5/3/
PY - 2022/5/3/
DO - 10.1109/JPROC.2022.3169146
VL - 5
SP -
SN - 1558-2256
KW - Magnetic resonance imaging
KW - Robots
KW - Imaging
KW - Robot sensing systems
KW - Robot kinematics
KW - Biomedical imaging
KW - Sensors
KW - Fiber optic sensors
KW - image-guided surgery
KW - magnetic resonance imaging (MRI)-compatible robots
KW - piezoelectric actuators
KW - sensors and actuators
KW - surgical robots
ER -
TY - JOUR
TI - Bistable and Multistable Actuators for Soft Robots: Structures, Materials, and Functionalities
AU - Chi, Yinding
AU - Li, Yanbin
AU - Zhao, Yao
AU - Hong, Yaoye
AU - Tang, Yichao
AU - Yin, Jie
T2 - ADVANCED MATERIALS
AB - Snap-through bistability is often observed in nature (e.g., fast snapping to closure of Venus flytrap) and the life (e.g., bottle caps and hair clippers). Recently, harnessing bistability and multistability in different structures and soft materials has attracted growing interest for high-performance soft actuators and soft robots. They have demonstrated broad and unique applications in high-speed locomotion on land and under water, adaptive sensing and fast grasping, shape reconfiguration, electronics-free controls with a single input, and logic computation. Here, an overview of integrating bistable and multistable structures with soft actuating materials for diverse soft actuators and soft/flexible robots is given. The mechanics-guided structural design principles for five categories of basic bistable elements from 1D to 3D (i.e., constrained beams, curved plates, dome shells, compliant mechanisms of linkages with flexible hinges and deformable origami, and balloon structures) are first presented, alongside brief discussions of typical soft actuating materials (i.e., fluidic elastomers and stimuli-responsive materials such as electro-, photo-, thermo-, magnetic-, and hydro-responsive polymers). Following that, integrating these soft materials with each category of bistable elements for soft bistable and multistable actuators and their diverse robotic applications are discussed. To conclude, perspectives on the challenges and opportunities in this emerging field are considered.
DA - 2022/5//
PY - 2022/5//
DO - 10.1002/adma.202110384
VL - 34
IS - 19
SP -
SN - 1521-4095
KW - bistability and multistability
KW - soft actuating materials
KW - soft actuators
KW - soft robots
KW - structural designs
ER -
TY - JOUR
TI - The overpoling effect of alternating current poling on rhombohedral Pb(Mg1/3Nb2/3)O-3-PbTiO3 single crystals
AU - Wan, Haotian
AU - Luo, Chengtao
AU - Kim, Hwang-Pill
AU - Chung, Ching-Chang
AU - Chang, Wei-Yi
AU - Yamashita, Yohachi
AU - Jiang, Xiaoning
T2 - APPLIED PHYSICS LETTERS
AB - The overpoling effect of alternating current poling (ACP) was studied on [001]-orientated rhombohedral Pb(Mg1/3Nb2/3)O3-0.26PbTiO3 (PMN-0.26PT) single crystals. Our experimental results showed that the property enhancement from the ACP was remarkable only when the poling cycle number (NL) was kept low. When ACP was continued after the saturation, dielectric and piezoelectric properties gradually dropped down to traditional direct current poled levels or even lower. Such a decrease in material properties caused by the large NL during ACP was defined as the “overpoling effect of ACP” in this study. The following lattice symmetry and domain structure characterization studies were performed through x-ray diffraction (XRD) and piezoelectric force microscopy (PFM) to find the origin of the overpoling effect. The XRD measurements combined with temperature dependence of dielectric properties demonstrated that the field-induced phase transition continued when the samples became overpoled. Further PFM measurements illustrated that the domain density of the overpoled ACP sample was significantly lower than that of the normal one, while the “2R” domain configuration was maintained through the ACP process. In addition, the hysteresis loop characterization indicated large decreases in the coercive fields. The discovered overpoling effect of ACP could help us understand the mechanisms of ACP and optimize the ACP process.
DA - 2022/5/9/
PY - 2022/5/9/
DO - 10.1063/5.0086057
VL - 120
IS - 19
SP -
SN - 1077-3118
ER -
TY - JOUR
TI - Fatigue Damage Diagnostics-Prognostics Framework for Remaining Life Estimation in Adhesive Joints
AU - Lyathakula, Karthik Reddy
AU - Yuan, Fuh-Gwo
T2 - AIAA JOURNAL
AB - This work presents an integrated damage diagnostics–prognostics framework for remaining useful life (RUL) estimation in the adhesively bonded joints under fatigue loading. A matching pursuit algorithm is proposed as the diagnostics technique for estimating the damage extent followed by the fatigue damage growth (FDG) simulator as the predictive model for simulating fatigue degradation. The framework calibrates the FDG simulator by quantifying uncertainties in fatigue model parameters using the damage extent data. Bayesian inference via the Markov chain Monte Carlo method is used to quantify uncertainties and estimate the probabilistic RUL from the quantified uncertainties. The FDG simulator encompasses a physics-based fatigue damage degradation model with an artificial neural network-based hybrid machine-learning model for tracing the damage progression. In the diagnostic technique, ultrasonic guided waves are excited into the structure using a pair of piezoelectric wafers, and the damage extent is quantified by reconstructing the reflected signal from the bond region. The proposed diagnostic technique is verified using the ultrasonic signal obtained from the finite element simulations. The damage prognostics part of the integrated framework is verified by estimating RUL in a mixed-mode failure joint specimen using the experimental fatigue damage progression data. In addition, the integrated framework is then verified by estimating RUL in two adhesively bonded joints: a single lap joint and a tapered single lap joint using Gaussian noise added synthetic data and diagnostic damage extent data.
DA - 2022/5/10/
PY - 2022/5/10/
DO - 10.2514/1.J060979
VL - 5
SP -
SN - 1533-385X
UR - http://dx.doi.org/10.2514/1.j060979
ER -
TY - JOUR
TI - Ca2+ signaling-mediated low-intensity pulsed ultrasound-induced proliferation and activation of motor neuron cells
AU - Truong, Thi-Thuyet
AU - Chiu, Wen-Tai
AU - Lai, Yi-Shyun
AU - Huang, Hsien
AU - Jiang, Xiaoning
AU - Huang, Chih-Chung
T2 - ULTRASONICS
AB - Motor neuron diseases (MND) including amyotrophic lateral sclerosis and Parkinson disease are commonly neurodegenerative, causing a gradual loss of nerve cells and affecting the mechanisms underlying changes in calcium (Ca2+)-regulated dendritic growth. In this study, the NSC-34 cell line, a population of hybridomas generated using mouse spinal cord cells with neuroblastoma, was used to investigate the effect of low-intensity pulsed ultrasound (LIPUS) as part of an MND treatment model. After NSC-34 cells were seeded for 24 h, LIPUS stimulation was performed on the cells at days 1 and 3 using a non-focused transducer at 1.15 MHz for 8 min. NSC-34 cell proliferation and morphological changes were observed at various LIPUS intensities and different combinations of Ca2+ channel blockers. The nuclear translocation of Ca2+-dependent transcription factors was also examined. We observed that the neurite outgrowth and cell number of NSC-34 significantly increased with LIPUS stimulation at days 2 and 4, which may be associated with the treatment's positive effect on the activation of Ca2+-dependent transcription factors, such as nuclear factor of activated T cells and nuclear factor-kappa B. Our findings suggest that the LIPUS-induced Ca2+ signaling and transcription factor activation facilitate the morphological maturation and proliferation of NSC-34 cells, presenting a promising noninvasive method to improve stimulation therapy for MNDs in the future.
DA - 2022/8//
PY - 2022/8//
DO - 10.1016/j.ultras.2022.106739
VL - 124
SP -
SN - 1874-9968
KW - Low-intensity pulsed ultrasound
KW - Motor neuron disease
KW - NSC-34 cell line
KW - Neurite outgrowth
KW - Morphology
KW - Ca (2+) signaling
KW - Ca (2+) -dependent transcription factors
ER -
TY - JOUR
TI - Cooperative Exchange-Based Platooning Using Predicted Fuel-Optimal Operation of Heavy-Duty Vehicles
AU - Earnhardt, Christian
AU - Groelke, Ben
AU - Borek, John
AU - Pelletier, Evan
AU - Brennan, Sean
AU - Vermillion, Chris
T2 - IEEE TRANSACTIONS ON INTELLIGENT TRANSPORTATION SYSTEMS
AB - Several driving situations exist where fuel-optimal driving in terms of aggregate performance can only be achieved when one or more vehicles incurs a sacrifice in its own fuel consumption. For these situations, an economic incentive is needed to entice that vehicle to participate in aggregate fuel-optimal driving. Focusing on platooning amongst automated heavy-duty vehicles and using real trucking routes, we examine the precise extent to which the benefits of platooning can be expanded through the incorporation of exchange-based incentives. We focus on two mechanisms for incentivized platooning: (i) incentivized “catch-up” along a prescribed highway route and (ii) incentivized re-routing to allow for platooning. For the incentivized “catch-up” mechanism, platoon capable vehicles begin at staggered positions, using a novel platoon catch-up algorithm capable of determining the fuel-optimal platoon engagement position and fuel-optimal velocity trajectories. Additionally, the incentivized re-routing mechanism determines the optimal route for a network of platoon-capable vehicles, allowing for a vehicle to reroute its trajectory to engage within the platoon. Because such scenarios will be shown to frequently lead to aggregate benefit, while actually hurting the fuel economy of one or more participants, we propose three methods for explicitly computing the monetary value of the exchange. Assuming a known trajectory and traffic pattern, the first uses the Shapley value to determine the exchange value. The second method adjusts the Shapley value, accounting for uncertainty associated with traffic modeling. The final method assumes a competitive market, requiring each individual operator to implement a bid.
DA - 2022/5/2/
PY - 2022/5/2/
DO - 10.1109/TITS.2022.3169390
SP -
SN - 1558-0016
KW - Fuels
KW - Aggregates
KW - Aerodynamics
KW - Biological system modeling
KW - Drag
KW - Routing
KW - Roads
KW - Optimization
KW - velocity control
KW - cooperative systems
KW - automotive control
KW - navigation
ER -
TY - JOUR
TI - Novel Surface Flow-Reversal Sensor Applied to Detection of Airfoil Stall
AU - Aleman, Maria A.
AU - Gopalarathnam, Ashok
AU - Granlund, Kenneth
T2 - JOURNAL OF AIRCRAFT
AB - No AccessEngineering NotesNovel Surface Flow-Reversal Sensor Applied to Detection of Airfoil StallMaria A. Aleman, Ashok Gopalarathnam and Kenneth GranlundMaria A. Aleman https://orcid.org/0000-0001-5538-0299North Carolina State University, Raleigh, North Carolina 27695*Ph.D. Candidate, Department of Mechanical and Aerospace Engineering; . Student Member AIAA.Search for more papers by this author, Ashok Gopalarathnam https://orcid.org/0000-0002-1119-7887North Carolina State University, Raleigh, North Carolina 27695†Professor, Department of Mechanical and Aerospace Engineering; . Associate Fellow AIAA.Search for more papers by this author and Kenneth Granlund https://orcid.org/0000-0002-0108-8038North Carolina State University, Raleigh, North Carolina 27695‡Assistant Professor, Department of Mechanical and Aerospace Engineering; . 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Google Scholar Previous article Next article FiguresReferencesRelatedDetails What's Popular Volume 59, Number 5September 2022 CrossmarkInformationCopyright © 2022 by Maria A. Aleman, Ashok Gopalarathnam, and Kenneth Granlund. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission. All requests for copying and permission to reprint should be submitted to CCC at www.copyright.com; employ the eISSN 1533-3868 to initiate your request. See also AIAA Rights and Permissions www.aiaa.org/randp. TopicsAerodynamic PerformanceAerodynamicsAeronautical EngineeringAeronauticsAviationAviation SafetyAvionicsFlight TestGuidance, Navigation, and Control SystemsPressure SensorsSensorsSkin FrictionTransducersTurbulenceWind Tunnels KeywordsFlow SensorsAirfoilWind Tunnel TestsLift CoefficientBoundary Layer SeparationAdverse Pressure GradientAerodynamic CharacteristicsTwo Dimensional FlowShear StressStatic PressurePDF Received28 October 2021Accepted4 April 2022Published online15 May 2022
DA - 2022/5/13/
PY - 2022/5/13/
DO - 10.2514/1.C036732
VL - 5
SP -
SN - 1533-3868
UR - https://doi.org/10.2514/1.C036732
ER -
TY - JOUR
TI - Age-Dependent Upper Limb Myoelectric Control Capability in Typically Developing Children
AU - Gonzalez, Miguel
AU - Su, Hao
AU - Fu, Qiushi
T2 - IEEE TRANSACTIONS ON NEURAL SYSTEMS AND REHABILITATION ENGINEERING
AB - Research in EMG-based control of prostheses has mainly utilized adult subjects who have fully developed neuromuscular control. Little is known about children's ability to generate consistent EMG signals necessary to control artificial limbs with multiple degrees of freedom. As a first step to address this gap, experiments were designed to validate and benchmark two experimental protocols that quantify the ability to coordinate forearm muscle contractions in typically developing children. Non-disabled, healthy adults and children participated in our experiments that aimed to measure an individual's ability to use myoelectric control interfaces. In the first experiment, participants performed 8 repetitions of 16 different hand/wrist movements. Using offline classification analysis based on Support Vector Machine, we quantified their ability to consistently produce distinguishable muscle contraction patterns. We demonstrated that children had a smaller number of highly independent movements (can be classified with >90% accuracy) than adults did. The second experiment measured participants' ability to control the position of a cursor on a 1-DoF virtual slide using proportional EMG control with three different visuomotor gain levels. We found that children had higher failure rates and slower average target acquisitions than adults did, primarily due to longer correction times that did not improve over repetitive practice. We also found that the performance in both experiments was age-dependent in children. The results of this study provide novel insights into the technical and empirical basis to better understand neuromuscular development in children with upper-limb loss.
DA - 2022///
PY - 2022///
DO - 10.1109/TNSRE.2022.3166800
VL - 30
SP - 1009-1018
SN - 1558-0210
KW - Electromyography
KW - Task analysis
KW - Pediatrics
KW - Electrodes
KW - Protocols
KW - Particle measurements
KW - Neuromuscular
KW - Myoelectric control
KW - pattern recognition
KW - motor development
KW - upper limb
KW - children
ER -
TY - JOUR
TI - Soft electrothermal actuators using silver nanowire heaters (vol 9, pg 3797, 2017)
AU - Yao, Shanshan
AU - Cui, Jianxun
AU - Cui, Zheng
AU - Zhu, Yong
T2 - NANOSCALE
AB - Correction for 'Soft electrothermal actuators using silver nanowire heaters' by Shanshan Yao et al., Nanoscale, 2017, 9, 3797-3805, https://doi.org/10.1039/C6NR09270E.
DA - 2022/5/5/
PY - 2022/5/5/
DO - 10.1039/d2nr90086f
VL - 14
IS - 17
SP - 6671-6671
SN - 2040-3372
ER -
TY - JOUR
TI - Scaling effects in the alternating-current poling of thin PIN-PMN-PT single crystals
AU - Kim, Hwang-Pill
AU - Wan, Haotian
AU - Lu, Xuanming
AU - Yamashita, Yohachi
AU - Jiang, Xiaoning
T2 - APPLIED PHYSICS LETTERS
AB - AC-poling of Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT) single crystals with a thickness of 0.06–0.16 mm was studied in this paper. Compared with DC-poled samples, enhancements in piezoelectric and dielectric properties can be obtained when the thickness is above 0.1 mm. However, inconsistency in poling effects was found in the crystals with thickness below 0.1 mm. To elucidate why such scaling effect arises, surface roughness was measured by an atomic force microscopy to correlate surface morphology and poling effects. It was found that non-uniform surface roughness led to inconsistent and decreased properties. Furthermore, temperature-dependent dielectric permittivity spectra were measured to explore how crystal thickness affects the thermal stability of ferroelectric phases. It is noted that complex changes in crystallographic symmetries emanate by decreasing thickness. Such phenomena can be attributed to more influential effects of surface morphology when thickness is reduced. We hope this work suggests a clue for solving the scaling effects of AC-poling on relaxor-PbTiO3 single crystals.
DA - 2022/4/4/
PY - 2022/4/4/
DO - 10.1063/5.0084994
VL - 120
IS - 14
SP -
SN - 1077-3118
ER -
TY - JOUR
TI - Flexible-Time Receding Horizon Iterative Learning Control With Application to Marine Hydrokinetic Energy Systems
AU - Cobb, Mitchell
AU - Reed, James
AU - Wu, Maxwell
AU - Mishra, Kirti D.
AU - Barton, Kira
AU - Vermillion, Chris
T2 - IEEE TRANSACTIONS ON CONTROL SYSTEMS TECHNOLOGY
AB - This brief presents an iterative learning control (ILC) framework for a class of repetitive control (RC) applications characterized by: 1) continuous operation; 2) flexible iteration time; and 3) an economic performance metric. Specifically, the effect of iteration-varying initial conditions, resulting from the continuous nature of the operation, is accounted for through an iteration domain receding horizon formulation. To address the need for flexible iteration times, the time-domain dynamics are transformed into path-domain dynamics characterized by a non-dimensional parameter spanning an iteration-invariant range. The resulting model is used to derive learning filters that minimize a multi-objective economic cost. The proposed methodology is applied to the control a kite-based marine hydrokinetic (MHK) system, which executes high-speed, repetitive flight paths with the objective of maximizing its lap-averaged power output. The proposed approach is validated via simulations of a medium-fidelity nonlinear model of a kite-based MHK system, and the results demonstrate robust and fast convergence of the kite to power-optimal flight patterns.
DA - 2022/4/22/
PY - 2022/4/22/
DO - 10.1109/TCST.2022.3165734
SP -
SN - 1558-0865
KW - Economics
KW - Time-domain analysis
KW - Iterative learning control
KW - Predictive models
KW - Indexes
KW - Trajectory
KW - Optimization
KW - Iterative learning control (ILC)
KW - marine energy systems
KW - optimal path following
KW - receding horizon control
KW - renewable energy systems
KW - repetitive control (RC)
ER -
TY - JOUR
TI - A Study on Thermal Properties of Composite Metal Foams for Applications in Tank Cars Carrying Hazardous Materials
AU - Rabiei, Afsaneh
AU - Amoafo-Yeboah, Nigel
AU - Huseboe, Evan
AU - Scemama, Claire
T2 - METAL-MATRIX COMPOSITES: ADVANCES IN PROCESSING, CHARACTERIZATION, PERFORMANCE AND ANALYSIS
AB - Each year, millions of tons of hazardous materials are shipped through tank cars on railroads. Accidents involving these tank cars can create punctures that release these hazardous materials into the surrounding area, resulting in potential fire and even explosions, human fatalities, and substantial damage to the environment. Despite all enhancements to mitigate the consequences of such accidents, there is still an immediate need for novel material with superior puncture and fire resistance with lower weight than the current carbon-steel in use, to improve the safety and efficacy of tank cars carrying hazardous materials (HAZMAT). Composite metal foamComposite metal foam (CMF) is a novel class of light-weight material made of closely packed metallic hollow spheres with a surrounding metallic matrix. In this study, the latest developments on evaluating the performance of composite metal foamComposite metal foam against extreme heat through both experimental and analytical approaches will be reported and compared to those properties of the base bulk steel materials in use.
DA - 2022///
PY - 2022///
DO - 10.1007/978-3-030-92567-3_23
SP - 367-379
SN - 2367-1696
KW - Composite metal foam
KW - Thermal conductivity
KW - Specific heat capacity
KW - Coefficient of thermal expansion
KW - Thermal diffusivity
ER -
TY - JOUR
TI - Understanding the role of bond point strain in the mechanical response of nonwoven polypropylene materials
AU - Garmabi, Alireza
AU - Elamin, Mohamed A.
AU - Bradford, Philip D.
AU - Pankow, Mark
T2 - JOURNAL OF COMPOSITE MATERIALS
AB - A method was developed to study micromechanics of a bond point in nonwoven polypropylene materials. The micromechanical behavior of the thermal bonded nonwovens was studied using the digital image correlation (DIC) technique to understand the bond points deformation during mechanical stretching. An electrospray technique was used as a fast and reliable method to create the speckle pattern on the nonwovens. Various parameters of the electrospraying and their influence on the pattern accuracy and repeatability was studied and the best pattern in terms of dot size and distribution was determined from experimentation. Plasma treatment also proved to be essential to enhance the uniform distribution and adherence of the particles on the surface. Unloaded DIC experiments were carried out and proved the accuracy of technique with errors of lower than 0.5% strain. An automated high-resolution tensile apparatus was built and loaded DIC experiments were carried out using the device. The fabric was tested in Machine Direction (MD) direction and Cross Direction (CD) directions, both showing good correlation with low errors. Average strain values in bond points were plotted against total strain in fabric and the results showed noticeable amounts of strains developed in the bond points, contradictory to most of the FEM models which consider no deformation in the bond points. Results also indicated that in MD direction deformation, bond points can experience more than 30% of the overall strain presented in the fabric.
DA - 2022/4/6/
PY - 2022/4/6/
DO - 10.1177/00219983221087332
SP -
SN - 1530-793X
KW - nonwovens
KW - mechanical testing
KW - micromechanics
KW - digital image correlation
ER -
TY - JOUR
TI - Physics-based Computational Method Predicting the Dielectric Properties of Polymer Nanocomposites
AU - Islam, Md Didarul
AU - Liu, Sipan
AU - Choi, Daniel
AU - Guo, Zhanhu
AU - Ryu, Jong Eun
T2 - APPLIED COMPOSITE MATERIALS
DA - 2022/4/9/
PY - 2022/4/9/
DO - 10.1007/s10443-022-10026-3
VL - 29
IS - 4
SP -
SN - 1573-4897
UR - https://doi.org/10.1007/s10443-022-10026-3
KW - Dielectric properties
KW - Effective permittivity
KW - Nanocomposites
KW - Energy storage
KW - Finite element analysis (FEA)
ER -
TY - JOUR
TI - Implications of Spatially Constrained Bipennate Topology on Fluidic Artificial Muscle Bundle Actuation
AU - Duan, Emily
AU - Bryant, Matthew
T2 - ACTUATORS
AB - In this paper, we investigate the design of pennate topology fluidic artificial muscle bundles under spatial constraints. Soft fluidic actuators are of great interest to roboticists and engineers, due to their potential for inherent compliance and safe human–robot interaction. McKibben fluidic artificial muscles are an especially attractive type of soft fluidic actuator, due to their high force-to-weight ratio, inherent flexibility, inexpensive construction, and muscle-like force-contraction behavior. The examination of natural muscles has shown that those with pennate fiber topology can achieve higher output force per geometric cross-sectional area. Yet, this is not universally true for fluidic artificial muscle bundles, because the contraction and rotation behavior of individual actuator units (fibers) are both key factors contributing to situations where bipennate muscle topologies are advantageous, as compared to parallel muscle topologies. This paper analytically explores the implications of pennation angle on pennate fluidic artificial muscle bundle performance with spatial bounds. A method for muscle bundle parameterization as a function of desired bundle spatial envelope dimensions has been developed. An analysis of actuation performance metrics for bipennate and parallel topologies shows that bipennate artificial muscle bundles can be designed to amplify the muscle contraction, output force, stiffness, or work output capacity, as compared to a parallel bundle with the same envelope dimensions. In addition to quantifying the performance trade space associated with different pennate topologies, analyzing bundles with different fiber boundary conditions reveals how bipennate fluidic artificial muscle bundles can be designed for extensile motion and negative stiffness behaviors. This study, therefore, enables tailoring the muscle bundle parameters for custom compliant actuation applications.
DA - 2022/3//
PY - 2022/3//
DO - 10.3390/act11030082
VL - 11
IS - 3
SP -
SN - 2076-0825
KW - biomimetic
KW - pennate topology
KW - soft actuators
KW - fluidic artificial muscles
KW - muscle topology
ER -
TY - JOUR
TI - Nondestructive examination of polymer composites by analysis of polymer-water interactions and damage-dependent hysteresis
AU - Idolor, Ogheneovo
AU - Berkowitz, Katherine
AU - Guha, Rishabh Debraj
AU - Grace, Landon
T2 - COMPOSITE STRUCTURES
AB - Polymer composites are currently replacing metals in applications requiring design flexibility, high strength-to-weight ratio, and corrosion resistance. However, the damage modes in these materials are very different from metals and require specialized techniques to detect internal flaws which may exist even in the absence of visible surface damage. This study proposes a technique for damage detection in polymer composites which uses naturally absorbed moisture as an ‘imaging’ agent. The locally higher concentration of water in the ‘free’ state at damaged regions and the tendency of such water to quickly migrate to and from damage sites—exhibiting damage-dependent hysteresis—is leveraged for damage detection. To identify damaged regions, a machine learning approach is adopted using logistic regression to classify local regions as ‘undamaged’ or ‘damaged’. New possibilities resulting from higher sensitivity levels achievable by damage-dependent hysteresis are highlighted, providing a pathway to field deployment of the novel damage detection technique.
DA - 2022/5/1/
PY - 2022/5/1/
DO - 10.1016/j.compstruct.2022.115377
VL - 287
SP -
SN - 1879-1085
KW - Nondestructive examination
KW - Polymer matrix composites
KW - Moisture diffusion
KW - Dielectric properties
KW - Machine learning
KW - Hysteresis
ER -
TY - JOUR
TI - Wall-Modeled Large Eddy Simulation of High Speed Flows
AU - Mettu, Balachandra R.
AU - Subbareddy, Pramod K.
T2 - AIAA JOURNAL
AB - The use of wall-modeled large-eddy simulation (WMLES) is explored in the context of compressible flows with a focus on cold-wall boundary layers and flows with shock-induced separation. It is observed that for cold-wall flows, a “mixed” scaling for the length scale appearing in the eddy viscosity formulation outperforms the classical semilocal scaling for obtaining predictions of heat flux and skin friction. A few shock/boundary-layer interaction (SBLI) cases are examined in some detail, and model modifications are proposed to overcome identified deficiencies. It is shown that using WMLES the low-frequency characteristics of SBLI at high Reynolds number can be quantitatively captured. A dynamically switched version of the equilibrium model is proposed; this shows promise for relatively inexpensive simulations at these conditions.
DA - 2022/3/16/
PY - 2022/3/16/
DO - 10.2514/1.J061501
SP -
SN - 1533-385X
ER -
TY - JOUR
TI - Effect of Pin Fins on Jet Impingement Heat Transfer Over a Rotating Disk
AU - Bhansali, Pratik S.
AU - Ramakrishnan, Kishore Ranganath
AU - Ekkad, Srinath V.
T2 - Journal of Heat Transfer
AB - Abstract Many engineering applications consist of rotating components that experience high-heat load. Applications like the gas turbine engine consist of rotating disks and the study of heat transfer over such rotating surfaces is of particular interest. In the case of gas turbines, the disk also needs to be protected from the ingress of hot turbine gases caused by the low-pressure region created due to the radially outward pumping of fluid close to the rotating surface. The present experimental study investigates the effects of introducing pin-fins on heat transfer over surface of a rotating gas-turbine disk. The experiments were conducted at rotational Reynolds numbers (ReR) of 5487–12,803 based on the disk diameter (D) and jet Reynolds numbers (Re) of 5000–18,000 based on the jet diameter. The effects of nozzle to target spacing (z/d=2−6), eccentricity of impingement (ε = 0−0.67), angle of impingement—both toward and away from the center (θi and θo=0 deg−20 deg), and the pin fin height (Hf=3.05 mm−19.05 mm) were studied. Steady-state temperature measurements were taken using thermocouples embedded in the disk close to the target surface, and area average Nusselt number (Nu) was calculated. The results have been compared with those for a smooth aluminum disk of equal dimensions and without any pin-fins. The average Nu was significantly enhanced by the presence of pin-fins. The enhancement was higher for lower values of Re, and the maximum enhancement was found to be 3.9 times that of a smooth disk for Re=5000. In the impingement dominant regime, the effect of disk rotation was minimal for a smooth disk, but the heat transfer increased with rotational speed in case of pin-fins. There was no impact of eccentricity on Nu for ε = 0 and 0.33. For ε = 0.67, the maximum reduction in enhancement over a smooth surface (21.95%) was observed when compared with coaxial impingement for stationary impingement for Re=18,000 and z/d=4. The effect of inclination angle was insignificant, and no clear trend could be established. Higher heat transfer rates were observed for z/d=6 with the increasing Re, and this effect diminished with the increase in the rotational speed. With the increase in pin-fin height, especially at higher values of Re, there was in increase in the value of Nu. Qualitative visualization of flow field has been performed for smooth and the pin-fin case using the commercial simulation package Ansys Fluent to further understand the flow features that result in the heat transfer enhancement.
DA - 2022/2/10/
PY - 2022/2/10/
DO - 10.1115/1.4053371
VL - 144
IS - 4
SP -
LA - en
OP -
SN - 0022-1481 1528-8943
UR - http://dx.doi.org/10.1115/1.4053371
DB - Crossref
KW - jet impingement
KW - turbine disk
KW - rotating disk
KW - pin-fins
ER -
TY - JOUR
TI - Organic solar powered greenhouse performance optimization and global economic opportunity
AU - Ravishankar, Eshwar
AU - Booth, Ronald E.
AU - Hollingsworth, Joseph A.
AU - Ade, Harald
AU - Sederoff, Heike
AU - DeCarolis, Joseph F.
AU - Brendan T. O'Connor,
T2 - ENERGY & ENVIRONMENTAL SCIENCE
AB - This work integrates greenhouse energy demand, solar power production, and plant growth modeling to assess the economic opportunity of organic solar powered greenhouses. Results show these systems have positive economic outlook across broad climates.
DA - 2022/3/10/
PY - 2022/3/10/
DO - 10.1039/d1ee03474j
SP -
SN - 1754-5706
ER -
TY - JOUR
TI - Electron beam sintering (EBS) process for Ultra-High Temperature Ceramics (UHTCs) and the comparison with traditional UHTC sintering and metal Electron Beam Melting (EBM) processes
AU - Pasagada, Venkata Keerti Vardhan
AU - Yang, Ni
AU - Xu, Chengying
T2 - CERAMICS INTERNATIONAL
AB - Ultra-high temperature ceramics (UHTCs) are refractory materials with unusual properties making them strong contenders for applications involving adverse and chemically aggressive environments. This paper presents an effort to process UHTCs using an additive manufacturing method, specifically Electron Beam Sintering (EBS) - adoption of the Electron Beam powder-bed fusion (PBF) process. Such a process shows that the processing and consolidation phenomenon of UHTCs are different from what is observed in the traditional sintering process of UHTCs and Electron Beam Melting (EBM) of typical metals or alloys. In this article, the EBS process of UHTCs is studied. The differences between EBS and the two aforementioned traditional processing methods are analyzed. The scientific hypotheses have been backed by experimental results on a ZrB2 – 30 vol% ZrSi2 UHTC mixture using an electron beam via Liquid Phase Sintering (LPS) theory. Efforts to develop processing conditions to fabricate dense and defect-free UHTC components are explored with the help of finite element (FE) simulations. Characterization of the EBS processed samples using Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-ray Spectroscopy (EDS) and X-ray Diffraction (XRD) revealed unique needle-like patterned grains of ZrB2 in a ZrSi2 matrix. Our findings demonstrate the feasibility of the EBS process to produce dense layers of UHTCs for coatings, potential three-dimensional, as well as complex-shaped applications.
DA - 2022/4/1/
PY - 2022/4/1/
DO - 10.1016/j.ceramint.2021.12.229
VL - 48
IS - 7
SP - 10174-10186
SN - 1873-3956
KW - Electron beam sintering
KW - Electron beam melting
KW - Ultra-high temperature ceramics
KW - Additive manufacturing
KW - Liquid phase sintering
ER -
TY - JOUR
TI - Novel 3-D Spacer Textiles to Protect Crops from Insect Infestation and That Enhance Plant Growth
AU - Cave, Grayson L.
AU - West, Andre J.
AU - McCord, Marian G.
AU - Koene, Bryan
AU - Beck, J. Benjamin
AU - Deguenon, Jean M.
AU - Luan, Kun
AU - Roe, R. Michael
T2 - AGRICULTURE-BASEL
AB - Pesticide-free, 3-D, spacer fabrics (Plant Armor Generation (PA Gen) 1 and 2) were investigated for proof-of-concept as an insect barrier to protect plants and improve plant agronomics for organic farming. The time to 50% penetration (TP50) for tobacco thrips, Frankliniella fusca (Hinds) adults in laboratory Petri dish bioassays was 30 and 175 min for PA Gen 1 and 2, respectively, and 12 min for the control (a commercially available, single layer-crop cover, Proteknet). PA Gen 2 was ≥90% resistant to penetration of unfed caterpillar neonates, Helicoverpa zea (Boddie), while the TP50‘s for Gen 1 and Proteknet were 3.1 and 2.35 h, respectively. In small cage studies, PA Gen 2 covered potted cabbage plants were 100% resistant to penetration by these insects through 10 d after which the study was ended. In small field plot studies for 3 summer months, cabbage plants grew approximately twice as fast when covered versus not covered with Gen 1 and Gen 2 without the need for insecticides or herbicides. This was not observed for the control crop cover. Martindale abrasion tests demonstrated Gen 1 and 2 were at least 6- and 1.8-fold more durable than the control crop cover used. Data are also presented on percentage light, water, air, and water vapor penetration across each textile and operational temperatures and humidity for cabbage plants covered and uncovered in small field plots.
DA - 2022/4//
PY - 2022/4//
DO - 10.3390/agriculture12040498
VL - 12
IS - 4
SP -
SN - 2077-0472
UR - https://doi.org/10.3390/agriculture12040498
KW - insect control
KW - organic farming
KW - non-insecticidal
KW - spacer fabric
KW - enhanced plant growth
ER -
TY - JOUR
TI - Mixture fraction measurement in turbulent non-premixed MILD jet flame using Rayleigh scattering
AU - Sahoo, Abinash
AU - Ramachandran, Aravind
AU - Narayanaswamy, Venkateswaran
AU - Lyons, Kevin M.
T2 - Applied Optics
AB - Turbulent combustion of jet flames in a hot diluted coflow of combustion products is conducive to the transition from conventional flamelet combustion to a regime of moderate or intense low oxygen dilution (MILD) combustion, which is commonly characterized by a very low emission and noise. MILD combustion is also characterized by distributed combustion where the net heat release is positive across the entire combustion domain. The turbulence/chemistry interactions in this regime that determine the flame structure, local temperature, and species distribution critically depend on the mixture fraction and scalar dissipation fields. However, there are no experimental tools to measure the mixture fraction field in a distributed (MILD) combustion regime. The present work offsets this limitation by demonstrating a Rayleigh scattering-based approach to measure mixture fraction in a turbulent ethylene MILD combustion zone. 1D counterflow flame simulations enabled mapping the locally calibrated Rayleigh scattering fields to mixture fractions in the fuel-rich regions. This approach also shows very low sensitivity to the local temperature and composition. Overall, the results provide compelling evidence that the distributed heat release does not significantly impact the turbulent processes of the flow-field for the conditions examined. The measurement uncertainty from this approach and its extension to more complex fuels are also discussed. The present technique is limited to mildly turbulent, fully MILD/distributed flame with representative scalar dissipation rates.
DA - 2022///
PY - 2022///
DO - 10.1364/AO.444109
VL - 61
IS - 9
SP - 2338-2351
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85127193360&partnerID=MN8TOARS
ER -
TY - JOUR
TI - Generalized Empirical Regret Bounds for Control of Renewable Energy Systems in Spatiotemporally Varying Environments
AU - Haydon, Ben
AU - Cole, Jack
AU - Dunn, Laurel
AU - Keyantuo, Patrick
AU - Chow, Fotini K.
AU - Moura, Scott
AU - Vermillion, Chris
T2 - JOURNAL OF DYNAMIC SYSTEMS MEASUREMENT AND CONTROL-TRANSACTIONS OF THE ASME
AB - Abstract This paper focuses on the empirical derivation of regret bounds for mobile systems that can optimize their locations in real-time within a spatiotemporally varying renewable energy resource. The case studies in this paper focus specifically on an airborne wind energy system, where the replacement of towers with tethers and a lifting body allows the system to adjust its altitude continuously, with the goal of operating at the altitude that maximizes net power production. While prior publications have proposed control strategies for this problem, often with favorable results based on simulations that use real wind data, they lack any theoretical or statistical performance guarantees. In this work, we make use of a very large synthetic dataset, identified through parameters from real wind data, to derive probabilistic bounds on the difference between optimal and actual performance, termed regret. The results are presented for a variety of control strategies, including maximum probability of improvement, upper confidence bound, greedy, and constant altitude approaches. In addition, we use dimensional analysis to generalize the aforementioned results to other spatiotemporally varying environments, making the results applicable to a wider variety of renewably powered mobile systems. Finally, to deal with more general environmental mean models, we introduce a novel approach to modify calculable regret bounds to accommodate any mean model through what we term an “effective spatial domain.”
DA - 2022/4/1/
PY - 2022/4/1/
DO - 10.1115/1.4052396
VL - 144
IS - 4
SP -
SN - 1528-9028
ER -
TY - JOUR
TI - Store Separation Trajectory Clusters from Machine Learning
AU - Gothard, William D.
AU - Granlund, Kenneth O.
T2 - JOURNAL OF AIRCRAFT
AB - Store separation of a generic, thin-finned, missile through a continuously oscillating shear layer into subsonic flow was conducted experimentally through 100 drop tests to identify potential groups of trajectories and statistical phenomena. Change in store pitch was observed using a high-speed camera. Trajectories were grouped using machine learning with a -means clustering, followed by a Gaussian mixture model clustering approach. The -means clustering revealed two primary groups and one outlier group. The statistical strength of the primary groups was confirmed with the Gaussian mixture model, which places 89% of trajectories into one of two groups. The existence of two primary groups is strong evidence of a bifurcation.
DA - 2022///
PY - 2022///
DO - 10.2514/1.C036261
VL - 59
IS - 1
SP - 117-125
SN - 1533-3868
KW - Gaussian Mixture Models
KW - Shear Layers
KW - Flow Conditions
KW - Aerodynamic Properties
KW - Karman Vortex Street
KW - Wind Tunnel Walls
KW - Cluster Analysis
KW - Fluid Structure Interaction
KW - Probability Distribution
KW - Dynamic Time Warping
ER -
TY - JOUR
TI - Deep thrombosis characterization using photoacoustic imaging with intravascular light delivery
AU - Tang, Yuqi
AU - Wu, Huaiyu
AU - Klippel, Paul
AU - Zhang, Bohua
AU - Huang, Hsiao-Ying Shadow
AU - Jing, Yun
AU - Jiang, Xiaoning
AU - Yao, Junjie
T2 - BIOMEDICAL ENGINEERING LETTERS
AB - Venous thromboembolism (VTE) is a condition in which blood clots form within the deep veins of the leg or pelvis to cause deep vein thrombosis. The optimal treatment of VTE is determined by thrombus properties such as the age, size, and chemical composition of the blood clots. The thrombus properties can be readily evaluated by using photoacoustic computed tomography (PACT), a hybrid imaging modality that combines the rich contrast of optical imaging and deep penetration of ultrasound imaging. With inherent sensitivity to endogenous chromophores such as hemoglobin, multispectral PACT can provide composition information and oxygenation level in the clots. However, conventional PACT of clots relies on external light illumination, which provides limited penetration depth due to strong optical scattering of intervening tissue. In our study, this depth limitation is overcome by using intravascular light delivery with a thin optical fiber. To demonstrate in vitro blood clot characterization, clots with different acuteness and oxygenation levels were placed underneath ten-centimeter-thick chicken breast tissue and imaged using multiple wavelengths. Acoustic frequency analysis was performed on the received PA channel signals, and oxygenation level was estimated using multispectral linear spectral unmixing. The results show that, with intravascular light delivery, clot oxygenation level can be accurately measured, and the clot age can thus be estimated. In addition, we found that retracted and unretracted clots had different acoustic frequency spectrum. While unretracted clots had stronger high frequency components, retracted clots had much higher low frequency components due to densely packed red blood cells. The PACT characterization of the clots was consistent with the histology results and mechanical tests.
DA - 2022/2/16/
PY - 2022/2/16/
DO - 10.1007/s13534-022-00216-0
SP -
SN - 2093-985X
KW - Thrombosis
KW - Photoacoustic tomography
KW - Internal light illumination
KW - Photoacoustic frequency
KW - Retracted blood clot
KW - Unretracted blood clot
KW - Blood oxygenation
ER -
TY - JOUR
TI - A new technique using background oriented schlieren for temperature reconstruction of an axisymmetric open reactive flow
AU - Wahls, Benjamin H.
AU - Ekkad, Srinath V
T2 - MEASUREMENT SCIENCE AND TECHNOLOGY
AB - Abstract A new technique, called 3D ray tracing, for refractive index field reconstruction of axisymmetric flows from displacement fields measured from background oriented schlieren (BOS) experiments is developed and applied to a lean premixed methane/air reactive flow at Reynolds number of 4000 on a 12 mm diameter circular burner. The temperature distribution is then calculated using a species independent direct relationship between refractive index, temperature, and ambient conditions. The error introduced by the approximation to reach this relationship is quantified using simulated flow fields and is found to be 8% within the inner unburnt region of the flow field, decreasing to 2% through the reaction zone, and then quickly reducing to 0% outside the flow field. The effect of random noise and reconstruction resolution on the accuracy of the method is assessed via application to synthetically generated data sets that mimic the characteristics of a heated air jet expelled into ambient. The novel 3D ray tracing allows for accurate temperature reconstructions of open axisymmetric reactive flows where 2D displacement fields are measured, which is shown to be a shortcoming of current direct methods in literature. Additionally, this is done without the need for any prior knowledge of flow field parameters; only ambient conditions to the system must be known. The simple experimental setup and low computational cost make this approach with BOS a good option for application into existing experimental combustion systems with minimal effort.
DA - 2022/5/1/
PY - 2022/5/1/
DO - 10.1088/1361-6501/ac51a5
VL - 33
IS - 5
SP -
SN - 1361-6501
KW - background oriented schlieren
KW - noninvasive
KW - temperature
KW - measurement
KW - reactive flow
ER -
TY - JOUR
TI - An effective PBPK model predicting dissolved drug transfer from a representative nasal cavity to the blood stream
AU - Dave, Sujal
AU - Kleinstreuer, Clement
AU - Chari, Sriram
T2 - JOURNAL OF AEROSOL SCIENCE
AB - Predicting the fate of nasally administered drugs is important for the understanding and possible improvement of in vivo performance. When computational fluid-particle dynamics (CFPD) results are coupled with a physiologically based pharmacokinetic (PBPK) model, drug concentrations in the blood stream can be obtained. Specifically, hybrid CFPD-PBPK simulations can predict inhaled particle transport, deposition, and uptake in the nasal mucus layers and subsequently absorbed drug migration from the nasal cavity to the blood stream.The computer simulation results of Chari et al. (2021) were used as input to a basic PBPK model to track the deposited and dissolved drugs from the nasal cavities to the blood stream. Employing the open-source toolbox OpenFOAM, our PBPK model predictions were compared with experimental in vivo data sets for different corticosteroids. The relative differences between experimental and simulated values of PK metrics, following administration of mometasone furoate nasal spray, were all 7% or less. Drug plasma concentrations based on different drug parameters, such as solubility and partition coefficient, were studied as well. The drug concentration in the plasma was found to increase with an increase in drug solubility (Cs = 0.02 mg/ml, 0.1 mg/ml, 0.2 mg/ml). The same trend was observed for different partition coefficients (Kow = 5e-3, 2, 5000), where the plasma concentration curve peaked for a partition coefficient of 5000. It was also observed that drug dosage controls the amount of residual drug concentrations in the plasma with the passage of time. Two different drug dosages were studied, ie, 50 μg and 800 μg, with the former being completely absorbed in the plasma after 8 h; however, in the latter case the drug was not completely absorbed after that time interval. These modeling and simulation results are useful for planning aspects in drug development, as the predictions provide physical insight to differences in device, formulation, and dosage selection.
DA - 2022/2//
PY - 2022/2//
DO - 10.1016/j.jaerosci.2021.105898
VL - 160
SP -
SN - 1879-1964
KW - Intranasal drugs
KW - Hybrid CFPD-PBPK model
KW - Disposition of inhaled drugs
KW - Pharmacokinetic modeling
KW - Drug concentrations in the blood stream
ER -
TY - JOUR
TI - Predictive Model of Dynamic Mechanical Properties of VE Damper Based on Acrylic Rubber-Graphene Oxide Composites Considering Aging Damage
AU - Ge, Teng
AU - Xu, Zhao-Dong
AU - Yuan, Fuh-Gwo
T2 - JOURNAL OF AEROSPACE ENGINEERING
AB - Because shock absorbers are an important component of high-rise buildings, it is essential to be able to detect damage to them. Viscoelastic (VE) dampers, as a common shock absorber, directly affect the safety and reliability of VE materials over the entire life of structures. This study is aimed at optimizing a high-dissipation VE material with excellent aging resistance. The VE damper was developed after aging of anti-aging and high-dissipation VE materials. To analyze the damping and mechanical properties of the VE dampers in detail, mechanical performance testing was conducted on VE dampers under various loading conditions, demonstrating that dampers had excellent mechanical properties and confirming the anti-aging properties of the VE materials. In addition, a fractional standard linear solid model based on damage modification is proposed, and aging is considered in the mathematical model of VE dampers as an indispensable factor. After the simulated value is compared to the experimental results, it is found that the fractional mathematical model that involves the aging factor precisely describes the real-time mechanical properties of the VE damper.
DA - 2022/3/1/
PY - 2022/3/1/
DO - 10.1061/(ASCE)AS.1943-5525.0001385
VL - 35
IS - 2
SP -
SN - 1943-5525
KW - Viscoelastic (VE) damper
KW - Aging resistance
KW - Mechanical performance tests
KW - Damage evolution
KW - Predictive model
ER -
TY - JOUR
TI - Utilization of Secondary Jet in Cavitation Peening and Cavitation Abrasive Jet Polishing
AU - Pang, Hao
AU - Ngaile, Gracious
T2 - MICROMACHINES
AB - The cavitation peening (CP) and cavitation abrasive jet polishing (CAJP) processes employ a cavitating jet to harden the surface or remove surface irregularities. However, a zero incidence angle between the jet and the surface limits the efficiency of these two processes. This limitation can be improved by introducing a secondary jet. The secondary jet interacts with the main jet, carrying bubbles to the proximity of the workpiece surface and aligning the disordered bubble collapse events. Through characterizing the treated surface of AL6061 in terms of the hardness distribution and surface roughness, it was found out that the secondary jet can increase the hardening intensity by 10%, whereas the material removal rate within a localized region increased by 66%. In addition, employing multiple secondary jets can create a patched pattern of hardness distribution. Another finding is that the hardening effect of the cavitation increases with the processing time at first and is then saturated.
DA - 2022/1//
PY - 2022/1//
DO - 10.3390/mi13010086
VL - 13
IS - 1
SP -
SN - 2072-666X
KW - cavitation
KW - peening
KW - jet polishing
ER -
TY - JOUR
TI - Electromagnetic Finite-Element Modeling of Induction Effects for Buried Objects in Magnetic Soils
AU - Elbadry, Mohamed H.
AU - Wetherington, Josh
AU - Zikry, Mohammed A.
T2 - IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING
AB - A frequency-based finite element (FE) framework has been developed to predict and understand the response of an electromagnetic induction (EMI) sensor due to buried targets. The EMI sensor is used to detect buried targets in magnetic nonconducting soils. The framework was verified with an analytical model that utilizes dipole approximations. The framework was then used to predict the electromagnetic (EM) response due to interrelated stimuli and properties. The results indicate that the sensor was not sensitive to small variations (0–200 mm) in the standoff height and lateral positions, and only showed a significant change in the response due to stand-off variations that were greater than 200 mm. This low sensitivity to minor variations in standoff height and lateral position signify that there are critical distances related to the EM response of buried objects. The response to different target conductivities and permeabilities was also investigated for steel and aluminum targets. The lower conductivity steel targets had EM responses, where the inductive limit was reached at higher frequencies than the higher conductivity aluminum targets. Variations in target permeabilities for steel showed that as permeabilities increased, the frequencies at which the inductive limit was reached also increased. This verified predictive approach can provide a methodology to characterize the EM response of buried objects for a broad class of buried object EM properties, geometries, and input stimuli.
DA - 2022///
PY - 2022///
DO - 10.1109/TGRS.2021.3124839
VL - 60
SP -
SN - 1558-0644
UR - https://doi.org/10.1109/TGRS.2021.3124839
KW - Electromagnetic induction (EMI)
KW - finite element method (FEM)
KW - magnetic susceptibility
KW - soil
ER -
TY - JOUR
TI - An Analysis of Sonothrombolysis and Cavitation for Retracted and Unretracted Clots Using Microbubbles Versus Low-Boiling-Point Nanodroplets
AU - Kim, Jinwook
AU - Bautista, Kathlyne Jayne B.
AU - Deruiter, Ryan M.
AU - Goel, Leela
AU - Jiang, Xiaoning
AU - Xu, Zhen
AU - Dayton, Paul A.
T2 - IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL
AB - The thrombolysis potential of low-boiling-point (-2 °C) perfluorocarbon phase-change nanodroplets (NDs) has previously been demonstrated on aged clots, and we hypothesized that this efficacy would extend to retracted clots. We tested this hypothesis by comparing sonothrombolysis of both unretracted and retracted clots using ND-mediated ultrasound (US+ND) and microbubble-mediated ultrasound (US+MB), respectively. Assessment data included clot mass reduction, cavitation detection, and cavitation cloud imaging in vitro. Acoustic parameters included a 7.9-MPa peak negative pressure and 180-cycle bursts with 5-Hz repetition (the corresponding duty cycle and time-averaged intensity of 0.09% and 1.87 W/cm2, respectively) based on prior studies. With these parameters, we observed a significantly reduced efficacy of US+MB in the retracted versus unretracted model (the averaged mass reduction rate from 1.83%/min to 0.54%/min). Unlike US+MB, US+ND exhibited less reduction of efficacy in the retracted model (from 2.15%/min to 1.04%/min on average). The cavitation detection results correlate with the sonothrombolysis efficacy results showing that both stable and inertial cavitation generated in a retracted clot by US+ND is higher than that by US+MB. We observed that ND-mediated cavitation shows a tendency to occur inside a clot, whereas MB-mediated cavitation occurs near the surface of a retracted clot, and this difference is more significant with retracted clots compared to unretracted clots. We conclude that ND-mediated sonothrombolysis outperforms MB-mediated therapy regardless of clot retraction, and this advantage of ND-mediated cavitation is emphasized for retracted clots. The primary mechanisms are hypothesized to be sustained cavitation level and cavitation clouds in the proximity of a retracted clot by US+ND.
DA - 2022/2//
PY - 2022/2//
DO - 10.1109/TUFFC.2021.3137125
VL - 69
IS - 2
SP - 711-719
SN - 1525-8955
KW - Ultrasonic imaging
KW - Acoustics
KW - Medical treatment
KW - Frequency control
KW - Coagulation
KW - Transducers
KW - Surface treatment
KW - Cavitation
KW - microbubble (MB)
KW - nanodroplet (ND)
KW - retracted clot
KW - sonothrombolysis
KW - thrombosis
ER -
TY - JOUR
TI - Recent progress on AC poling of relaxor-PbTiO3 ferroelectric single crystals: a review
AU - Sun, Yiqin
AU - Karaki, Tomoaki
AU - Yamashita, Yohachi
T2 - JAPANESE JOURNAL OF APPLIED PHYSICS
AB - Abstract Compared to conventional DC poling (DCP) treatment, in 2014 a novel technology, AC poling (ACP) treatment, was found to be a low-cost, time-saving and smart-process method to significantly enhance the properties of relaxor-PbTiO 3 (PT) ferroelectric single crystal (SC) transducers. In total, over 35 papers have been reported since 2018 in which researchers achieved a piezoelectric coefficient of ( d 33 ) > 4000 pC/N and electromechanical coupling factors of ( k 33 ) > 96% for the ACP SCs. In this review, we introduce the history of ACP study on relaxor-PT SCs, and our research group’s ACP study during the past three years. In particular, we focus on ACP conditions and their mechanisms of binary (1- x )Pb(Mg 1/3 Nb 2/3 )O 3 - x PbTiO 3 (PMN-PT) and ternary (1- x - y )Pb(In 1/2 Nb 1/2 )O 3 - y Pb(Mg 1/3 Nb 2/3 )O 3 - x PbTiO 3 (PIN-PMN-PT) SCs near the morphotropic phase boundary (MPB). Furthermore, we provide insight for further studies on optimal ACP conditions and the reduction of spurious-mode vibrations (SMVs). This work offers promising prospects and practical value for high-end ultrasonic imaging probe transducers.
DA - 2022/2/1/
PY - 2022/2/1/
DO - 10.35848/1347-4065/ac3a90
VL - 61
IS - SB
SP -
SN - 1347-4065
KW - AC poling
KW - ferroelectric
KW - single crystal
KW - ultrasonic transducer
KW - spurious-mode vibration
ER -
TY - JOUR
TI - Motor unit buckling in variable recruitment fluidic artificial muscle bundles: implications and mitigations
AU - Mazzoleni, Nicholas
AU - Kim, Jeong Yong
AU - Bryant, Matthew
T2 - SMART MATERIALS AND STRUCTURES
AB - Abstract Fluidic artificial muscles (FAMs) are a popular actuation choice due to their compliant nature and high force-to-weight ratio. Variable recruitment is a bio-inspired actuation strategy in which multiple FAMs are combined into motor units that can be pressurized sequentially according to load demand. In a traditional ‘fixed-end’ variable recruitment FAM bundle, inactive units and activated units that are past free strain will compress and buckle outward, resulting in resistive forces that reduce overall bundle force output, increase spatial envelope, and reduce operational life. This paper investigates the use of inextensible tendons as a mitigation strategy for preventing resistive forces and outward buckling of inactive and submaximally activated motor units in a variable recruitment FAM bundle. A traditional analytical fixed-end variable recruitment FAM bundle model is modified to account for tendons, and the force–strain spaces of the two configurations are compared while keeping the overall bundle length constant. Actuation efficiency for the two configurations is compared for two different cases: one case in which the radii of all FAMs within the bundle are equivalent, and one case in which the bundles are sized to consume the same amount of working fluid volume at maximum contraction. Efficiency benefits can be found for either configuration for different locations within their shared force–strain space, so depending on the loading requirements, one configuration may be more efficient than the other. Additionally, a study is performed to quantify the increase in spatial envelope caused by the outward buckling of inactive or low-pressure motor units. It was found that at full activation of recruitment states 1, 2, and 3, the tendoned configuration has a significantly higher volumetric energy density than the fixed-end configuration, indicating that the tendoned configuration has more actuation potential for a given spatial envelope. Overall, the results show that using a resistive force mitigation strategy such as tendons can completely eliminate resistive forces, increase volumetric energy density, and increase system efficiency for certain loading cases. Thus, there is a compelling case to be made for the use of tendoned FAMs in variable recruitment bundles.
DA - 2022/3/1/
PY - 2022/3/1/
DO - 10.1088/1361-665X/ac49d9
VL - 31
IS - 3
SP -
SN - 1361-665X
KW - bioinspiration
KW - fluidic artificial muslces
KW - variable recruitment
KW - McKibben actuators
KW - motor unit buckling
ER -
TY - JOUR
TI - Evoked Tactile Feedback and Control Scheme on Functional Utility of Prosthetic Hand
AU - Vargas, Luis
AU - Huang, He
AU - Zhu, Yong
AU - Hu, Xiaogang
T2 - IEEE ROBOTICS AND AUTOMATION LETTERS
AB - Fine manual control relies on intricate action-perception coupling to effectively interact with objects . Here, we evaluated how electrically evoked artificial tactile sensation can be integrated into the functional utility of a prosthetic hand. Using different myoelectric-control strategies, participants performed a modified box-and-block task using a prosthetic hand. Transcutaneous nerve stimulation was employed to elicit somatotopic fingertip tactile feedback reflecting prosthetic fingertip forces. This feedback was evoked using an electrode grid placed along the participants’ upper arm targeting the median and ulnar nerve bundles. Myoelectric signals from the finger flexor and extensor controlled the prosthetic joint velocity or position. Participants lifted, held, and transported cubes of varying weights using their minimum grip forces. The results showed that participants exerted lower forces and presented lower number of failed trials (prematurely dropped objects) when feedback was provided with respect to without feedback. We also found that position control required more flexor muscle activation compared with velocity control when tactile feedback was provided. Our findings reveal that non-invasively evoked tactile feedback could be used to effectively enable human-in-the-loop control of a prosthetic hand. The outcomes can provide a platform to characterize the action-perception couplings during prosthetic control, in order to improve user experience and system functionality.
DA - 2022/4//
PY - 2022/4//
DO - 10.1109/LRA.2021.3139147
VL - 7
IS - 2
SP - 1300-1307
SN - 2377-3766
KW - Tactile sensation
KW - transcutaneous nerve stimulation
KW - prosthetic hand
KW - functional task
KW - haptic feedback
ER -
TY - JOUR
TI - AI reflections in 2021
AU - Buckner, Cameron
AU - Miikkulainen, Risto
AU - Forrest, Stephanie
AU - Milano, Silvia
AU - Zou, James
AU - Prunk, Carina
AU - Irrgang, Christopher
AU - Cohen, I. Glenn
AU - Su, Hao
AU - Murphy, Robin R.
AU - Taylor, Russell H.
AU - Krieger, Axel
AU - Kovac, Mirco
AU - Sadowski, Jathan
AU - Marda, Vidushi
T2 - NATURE MACHINE INTELLIGENCE
AB - For a third year in a row, we followed up with authors of several recent Comments and Perspectives in Nature Machine Intelligence about what happened after their article was published: how did the topic they wrote about develop, did they gain new insights, and what are their hopes and expectations for AI in 2022?
DA - 2022/1/25/
PY - 2022/1/25/
DO - 10.1038/s42256-021-00435-7
VL - 1
SP -
SN - 2522-5839
ER -
TY - JOUR
TI - Analysis of improved oral drug delivery with different helical stream inhalation modes
AU - Gurumurthy, Adithya
AU - Kleinstreuer, Clement
T2 - COMPUTERS IN BIOLOGY AND MEDICINE
AB - A challenging aspect of pulmonary drug delivery devices, e.g., metered dose inhalers (MDIs), is to deliver therapeutic drugs to prescribed target locations at the required dosage level. In this study, validated computer simulations of micron-drug inhalation with angled or radially positioned helical fluid-particle streams are simulated and analyzed. For a suitable swirl number significant improvements in drug delivery, especially to deeper lung regions, have been achieved. Specifically, considering realistic polydisperse particle distributions at the mouth inlet for a subject-specific upper lung airway geometry, a 10-degree angled helical stream increased the local efficacy by up to 26% in comparison to a conventional helical stream, causing an overall dosage of about 60% to the deep lung. Considering lobe-specific drug targeting scenarios, while using an off-center, i.e., radially well positioned, helical-flow mouthpiece, the local particle-deposition efficacy increased from 9% to 24% in the left lobe and from 25% to 38% in the right lobe in comparison to conventional drug-aerosol stream released from the central position. The efficacy of helical streams for pulmonary drug delivery applications has been established.
DA - 2022/2//
PY - 2022/2//
DO - 10.1016/j.compbiomed.2021.105132
VL - 141
SP -
SN - 1879-0534
KW - Pulmonary drug delivery
KW - Polydisperse particle distribution
KW - Subject-specific upper lung airway geometry
KW - Helical drug-aerosol streams
KW - Swirl number
KW - Angled helical injection
KW - Radially positioned helical injection
KW - Lobe-specific drug targeting
ER -
TY - JOUR
TI - Boundary curvature guided programmable shape-morphing kirigami sheets
AU - Hong, Yaoye
AU - Chi, Yinding
AU - Wu, Shuang
AU - Li, Yanbin
AU - Zhu, Yong
AU - Yin, Jie
T2 - NATURE COMMUNICATIONS
AB - Abstract Kirigami, a traditional paper cutting art, offers a promising strategy for 2D-to-3D shape morphing through cut-guided deformation. Existing kirigami designs for target 3D curved shapes rely on intricate cut patterns in thin sheets, making the inverse design challenging. Motivated by the Gauss-Bonnet theorem that correlates the geodesic curvature along the boundary with the Gaussian curvature, here, we exploit programming the curvature of cut boundaries rather than the complex cut patterns in kirigami sheets for target 3D curved morphologies through both forward and inverse designs. The strategy largely simplifies the inverse design. Leveraging this strategy, we demonstrate its potential applications as a universal and nondestructive gripper for delicate objects, including live fish, raw egg yolk, and a human hair, as well as dynamically conformable heaters for human knees. This study opens a new avenue to encode boundary curvatures for shape-programing materials with potential applications in soft robotics and wearable devices.
DA - 2022/1/26/
PY - 2022/1/26/
DO - 10.1038/s41467-022-28187-x
VL - 13
IS - 1
SP -
SN - 2041-1723
ER -
TY - JOUR
TI - Design, analysis, and validation of an orderly recruitment valve for bio-inspired fluidic artificial muscles
AU - Vemula, Dheeraj
AU - Kim, Jeong Yong
AU - Mazzoleni, Nicholas
AU - Bryant, Matthew
T2 - BIOINSPIRATION & BIOMIMETICS
AB - Biological musculature employs variable recruitment of muscle fibers from smaller to larger units as the load increases. This orderly recruitment strategy has certain physiological advantages like minimizing fatigue and providing finer motor control. Recently fluidic artificial muscles (FAM) are gaining popularity as actuators due to their increased efficiency by employing bio-inspired recruitment strategies such as active variable recruitment (AVR). AVR systems use a multi-valve system (MVS) configuration to selectively recruit individual FAMs depending on the load. However, when using an MVS configuration, an increase in the number of motor units in a bundle corresponds to an increase in the number of valves in the system. This introduces greater complexity and weight. The objective of this paper is to propose, analyze, and demonstrate an orderly recruitment valve (ORV) concept that enables orderly recruitment of multiple FAMs in the system using a single valve. A mathematical model of an ORV-controlled FAM bundle is presented and validated by experiments performed on a proof-of-concept ORV experiment. The modeling is extended to explore a case study of a 1-DOF robot arm system consisting of an electrohydraulic pressurization system, ORV, and a FAM-actuated rotating arm plant and its dynamics are simulated to further demonstrate the capabilities of an ORV-controlled closed-loop system. An orderly recruitment strategy was implemented through a model-based feed forward controller. To benchmark the performance of the ORV, a conventional MVS with equivalent dynamics and controller was also implemented. Trajectory tracking simulations on both the systems revealed lower tracking error for the ORV controlled system compared to the MVS controlled system due to the unique cross-flow effects present in the ORV. However, the MVS, due to its independent and multiple valve setup, proved to be more adaptable for performance. For example, modifications to the recruitment thresholds of the MVS demonstrated improvement in tracking error, albeit with a sacrifice in efficiency. In the ORV, tracking performance remained insensitive to any variation in recruitment threshold. The results show that compared to the MVS, the ORV offers a simpler and more compact valving architecture at the expense of moderate losses in control flexibility and performance.
DA - 2022/3/1/
PY - 2022/3/1/
DO - 10.1088/1748-3190/ac4381
VL - 17
IS - 2
SP -
SN - 1748-3190
KW - fluidic artificial muscle
KW - variable recruitment
KW - McKibben actuator
ER -
TY - JOUR
TI - Design of a scalable, flexible, and durable thermoelectric cooling device for soft electronics using Kirigami cut patterns
AU - Rosenberg, Z. B.
AU - Weiner, N. C.
AU - Shahariar, H.
AU - Li, B. M.
AU - Peavey, J. L.
AU - Mills, A. C.
AU - Losego, M. D.
AU - Jur, J. S.
T2 - FLEXIBLE AND PRINTED ELECTRONICS
AB - Abstract A flexible, soft thermoelectric cooling device is presented that shows potential for human cooling applications in wearable technologies and close-to-body applications. Current developments lack integration feasibility due to non-scalable assembly procedures and unsuitable materials for comfortable and durable integration into products. Our devices have been created and tested around the need to conform to the human body which we have quantified through the creation of a repeatable drape testing procedure, a metric used in the textile industry. Inspired by mass manufacturing constraints, our flexible thermoelectric devices are created using commercially available materials and scalable processing techniques. Thermoelectric legs are embedded in a foam substrate to provide flexibility, while Kirigami-inspired cuts are patterned on the foam to provide the drape necessary for mimicking the performance of textile and close to body materials. In total, nine different configurations, three different fill factors and three different Kirigami cut patterns were fabricated and inspected for thermal characterization, mechanical testing, flexibility and drape. Our studies show that adding Kirigami patterns can increase the durability of the device, improve the flexibility, decrease the drape coefficient, and have <1% of impact on cooling performance at higher fill factors (>1.5%), reaching temperature differences up to 4.39 °C ± 0.17 °C between the hot and cold faces of the device. These thermoelectric cooling devices show great flexibility, durability, and cooling for integration into soft cooling products.
DA - 2022/3/1/
PY - 2022/3/1/
DO - 10.1088/2058-8585/ac48a0
VL - 7
IS - 1
SP -
SN - 2058-8585
KW - e-textiles
KW - flexible thermoelectrics
KW - thermoelectric cooling devices
KW - flexible electronics
KW - wearable electronics
ER -
TY - JOUR
TI - Multilayer microfluidic platform for the study of luminal, transmural, and interstitial flow
AU - Lee, Gi-hun
AU - Huang, Stephanie A.
AU - Aw, Wen Y.
AU - Rathod, Mitesh L.
AU - Cho, Crescentia
AU - Ligler, Frances S.
AU - Polacheck, William J.
T2 - BIOFABRICATION
AB - Efficient delivery of oxygen and nutrients to tissues requires an intricate balance of blood, lymphatic, and interstitial fluid pressures (IFPs), and gradients in fluid pressure drive the flow of blood, lymph, and interstitial fluid through tissues. While specific fluid mechanical stimuli, such as wall shear stress, have been shown to modulate cellular signaling pathways along with gene and protein expression patterns, an understanding of the key signals imparted by flowing fluid and how these signals are integrated across multiple cells and cell types in native tissues is incomplete due to limitations with current assays. Here, we introduce a multi-layer microfluidic platform (MμLTI-Flow) that enables the culture of engineered blood and lymphatic microvessels and independent control of blood, lymphatic, and IFPs. Using optical microscopy methods to measure fluid velocity for applied input pressures, we demonstrate varying rates of interstitial fluid flow as a function of blood, lymphatic, and interstitial pressure, consistent with computational fluid dynamics (CFD) models. The resulting microfluidic and computational platforms will provide for analysis of key fluid mechanical parameters and cellular mechanisms that contribute to diseases in which fluid imbalances play a role in progression, including lymphedema and solid cancer.
DA - 2022/4/1/
PY - 2022/4/1/
DO - 10.1088/1758-5090/ac48e5
VL - 14
IS - 2
SP -
SN - 1758-5090
KW - microfluidics
KW - vascular biology
KW - interstitial flow
KW - hemodynamics
KW - biofluid mechanics
KW - mechanotransduction
ER -
TY - JOUR
TI - Spurious-mode vibrations caused by alternating current poling and their solution process for Pb(Mg1/3Nb2/3)O-3-PbTiO3 single crystals
AU - Sun, Yiqin
AU - Karaki, Tomoaki
AU - Fujii, Tadashi
AU - Yamashita, Yohachi John
T2 - JOURNAL OF MATERIOMICS
AB - The effects of alternating current poling (ACP) at 80 °C on electrical properties of [001]-oriented 0.72 Pb(Mg1/3Nb2/3)O3-0.28PbTiO3 (PMN-28PT) single crystals (SCs) have been investigated. The square-wave ACP SCs poled at high voltage (HV, 5 kVrms/cm) occasionally showed large fluctuations and low opposite values of piezoelectric coefficient (d33 = ± 1370 pC/N) in one plate. This revealed spurious-mode vibrations (SMV) of impedance spectrum. However, after depolarizing and repolarizing the sample with a sine-wave ACP at low voltage (LV, 3.5 kVrms/cm), the d33 enhanced to be 1720 pC/N (+26%) and did not exhibit large fluctuation or opposite values in one plate any more. The impedance spectrum became clean and the abnormal SMV disappeared. We proposed four possible mechanisms of the SMV, and speculate that the main cause maybe by macro-scale sub-domain structure and/or phase change in the main domain structure and/or phase in the SC plate due to the specific poling conditions not eternal mechanical damage of PMN-PT SCs. This study will be useful to realize a high d33 and improve other properties of PMN-PT ACP SC ultrasonic transducers without any SMV for high-frequency medical imaging equipment.
DA - 2022/1//
PY - 2022/1//
DO - 10.1016/j.jmat.2021.05.002
VL - 8
IS - 1
SP - 96-103
SN - 2352-8478
KW - Alternating current poling
KW - Ferroelectric single crystal
KW - Ultrasonic transducer
KW - Spurious mode vibration
KW - Piezoelectric property
ER -
TY - JOUR
TI - Overall Cooling Effectiveness of Effusion Cooled Can Combustor Liner Under Reacting and Non-Reacting Conditions
AU - Ahmed, Shoaib
AU - Ramakrishnan, Kishore Ranganath
AU - Ekkad, Srinath V
T2 - JOURNAL OF THERMAL SCIENCE AND ENGINEERING APPLICATIONS
AB - Abstract Emphasis on lean premixed combustion in modern low NOX combustion chambers limits the air available for cooling the combustion liner. Hence, the development of optimized liner cooling designs is imperative for effective usage of available coolant. An effective way to cool a gas turbine combustor liner is through effusion cooling. Effusion cooling (also known as full-coverage film cooling) involves uniformly spaced holes distributed throughout the liner’s curved surface area. This study presents findings from an experimental study on the characterization of the overall cooling effectiveness of an effusion-cooled liner wall, which was representative of a can combustor under heated flow (non-reacting) and lean-combustion (reacting) conditions. The model can combustor was equipped with an industrial swirler, which subjected the liner walls to engine representative flow and combustion conditions. In this study, two different effusion cooling liners with an inline and staggered arrangement of effusion holes have been studied. Non-dimensionalized streamwise hole-to-hole spacing (z/d) and spanwise hole-to-hole spacing (r/d) of 10 were used for both the effusion liners. These configurations were tested for five different blowing ratios ranging from 0.7 to 4.0 under both reacting and non-reacting conditions. The experiments were carried out at a constant main flow Reynolds number (based on combustor diameter) of 12,500. The non-reacting experiments were carried out by heating the mainstream air, and the reacting experiments were carried out under flame conditions at a total equivalence ratio of 0.65. Infrared thermography (IRT) was used to measure the liner outer surface temperature, and detailed overall effectiveness values were determined under steady-state conditions. It was observed that overall cooling effectiveness trends were different under reacting and non-reacting conditions. The cooling effectiveness for the non-reacting experiments exhibited a decreasing trend, and no consistent location of minimum cooling effectiveness was observed for the range of blowing ratios investigated in this study. For the reacting cases, the cooling effectiveness first follows a decreasing trend, reaches a distinct minimum, and then increases till the end of the combustor. Under non-reacting conditions, the staggered configuration was 9–25% more effective than inline configuration, and under reacting conditions, the staggered configuration was 4–8% more effective than inline configuration. From this study, it is clear that the coolant flame interaction for the reacting experiments impacted the liner cooling effectiveness and led to different overall cooling effectiveness distribution on the liner when compared with the non-reacting experiments.
DA - 2022/2/1/
PY - 2022/2/1/
DO - 10.1115/1.4051371
VL - 14
IS - 2
SP -
SN - 1948-5093
KW - heat transfer
KW - effusion cooling
KW - combustion
KW - combustion and reactive flows
KW - experimental
KW - measurement techniques
KW - gas turbine heat transfer
ER -
TY - JOUR
TI - Characterization of Transient Wall Heat Load for a Low NOx Lean Premixed Swirl Stabilized Can Combustor Under Reacting Conditions
AU - Ramakrishnan, Kishore Ranganath
AU - Ahmed, Shoaib
AU - Ekkad, Srinath V
T2 - JOURNAL OF THERMAL SCIENCE AND ENGINEERING APPLICATIONS
AB - Abstract As stringent emissions controls are being placed on gas turbines, modern combustor design optimization is contingent on the accurate characterization of the combustor flame side heat loads. Power generation turbines are increasingly moving toward natural gas, biogas, and syngas, whose composition is highly dependent on the sourcing location. With fuel flexible nozzles, it is important to understand the heat load from various gas mixtures to optimize the cooling design to make sure the liner is not under/over cooled for some mixtures as this has a larger effect on NOx/CO emissions. In addition to knowing the heat load distribution, it is important to understand the peak heat load under start/stop transient conditions which tend to be much higher than steady-state/cruise altitude heat loads. The present work focuses on the experimental measurement of the transient heat load along a can combustor under reacting conditions for a swirl-stabilized premixed methane–air flame. Tests were carried out under various equivalence ratios, Reynolds numbers, and pilot fuel flowrate. An infrared camera was used to measure the inner and outer wall temperatures of the liner to calculate the liner heat load. Particle image velocimetry (PIV) was employed to visualize the flowfield for various reacting conditions studied in this work. Based on the heat transfer study, a detailed report of transient heat load along the length of the liner wall has been presented here. Initial start transient heat load on the liner wall is ∼10–40% more than the steady-state heat load.
DA - 2022/2/1/
PY - 2022/2/1/
DO - 10.1115/1.4051375
VL - 14
IS - 2
SP -
SN - 1948-5093
KW - gas turbine
KW - combustion
KW - heat transfer
KW - low NOx
KW - swirl stabilized
KW - premixed
KW - combustion and reactive flows
KW - experimental
KW - measurement techniques
KW - very high-temperature heat transfer
ER -
TY - JOUR
TI - A study on the creep behavior of alloy 709 using in-situ scanning electron microscopy
AU - Lall, Amrita
AU - Bowen, Paul
AU - Rabiei, Afsaneh
T2 - MATERIALS CHARACTERIZATION
AB - In this research, an experimental evaluation of creep properties of Alloy 709 in the temperature range of 750–850 °C was undertaken. Alloy 709 is a novel austenitic stainless steel with 20% Cr and 25% Ni by wt% that was developed for application in structural components of nuclear power plants. Creep rupture tests were conducted in an in-situ heating-loading and Scanning Electron Microscope (SEM) unit equipped with Electron Backscatter Diffraction (EBSD) detector and Energy Dispersive Spectroscopy (EDS). “Real-time” creep damage mechanisms of Alloy 709 at various stresses and temperatures using a flat, un-notched sample with continuously reducing cross-section is studied so that the failure and maximum creep damage occurred at the center of the sample where the in-situ SEM imaging could be focused. Accelerated creep tests at temperatures and stresses above service conditions were performed by employing multiple blocks of constant loads where the loads were increased once the sample attained constant creep rate, indicating a secondary creep regime. This technique ensures multiple data points can be obtained from the same test, saves the time required for an otherwise long-term creep test and usage of SEM. Coincident Site Lattice (CSL) boundary maps were collected as control maps before testing, and the grain boundaries were observed during the creep test to understand the effect of grain boundary character on the creep damage mechanism. Void growth, grain boundary separation, and sliding were found to be the main creep mechanisms whose rate is dependent on stress and temperature. Failure mechanisms studied on the fracture surface using SEM fractography were correlated to the sample surface observations to create complementary information to better understand the underline creep mechanism of Alloy 709.
DA - 2022/1//
PY - 2022/1//
DO - 10.1016/j.matchar.2021.111587
VL - 183
SP -
SN - 1873-4189
KW - In-situ scanning electron microscope
KW - Creep
KW - Alloy 709
KW - Austenitic stainless steel
ER -
TY - JOUR
TI - A numerical and experimental approach to compare the effect of sample thickness in small in-situ SEM and large ex-situ tensile testing in Alloy 709
AU - Lall, Amrita
AU - Bowen, Paul
AU - Rabiei, Afsaneh
T2 - MATERIALS CHARACTERIZATION
AB - ASTM standards for tensile tests define specific sample size requirements regardless of grain size of the material. However, sample size requirements for testing should be considered in conjunction with the number of grains within its reduced cross-sectional area. This is particularly important for in-situ Scanning Electron Microscope (SEM) tensile tests, as they have to be conducted on smaller samples. In this study, a comprehensive experimental and numerical evaluation of the effect of specimen thickness (and the resulting number of grains within the cross-section) were conducted using in-situ SEM tensile test (on sub-millimeter thick samples) and ex-situ tensile tests (on samples of 0.68–5.9 mm thickness) and the results are compared with FEM simulations outcome. All tests were conducted at room temperature and the results are correlated to the number of grains within the thickness of specimens. The tensile test results indicated that even though the 0.2% proof stress and the tensile strength do not vary for the current range of thicknesses (with number of grains in the cross-section varying from 13 to 118), a difference in necking mechanism exists. Post tensile strength, thinner samples undergo more shear failure and diagonal localized necking whereas thicker samples experience more diffuse necking indicated by decreased area of shear failure at the edges and increased area of dimpled tensile failure at the center of the sample. FEM results complement the experimental findings by showing the formation of conjugated localized shear bands on the upper and lower surface in the 0.68 mm thick sample and shear bands combining to form singular shear bands in thicker samples. These results also confirm the validity of the in-situ SEM tensile tests conducted on thinner samples as long as the required minimum number of grains exist within the cross-section.
DA - 2022/2//
PY - 2022/2//
DO - 10.1016/j.matchar.2021.111614
VL - 184
SP -
SN - 1873-4189
KW - Alloy 709
KW - Tensile test
KW - Size effect
KW - Necking
KW - Grain size
KW - Finite element modeling
ER -
TY - JOUR
TI - A Direct Comparison of Node and Element-Based Finite Element Modeling Approaches to Study Tissue Growth
AU - Howe, Danielle
AU - Dixit, Nikhil N.
AU - Saul, Katherine R.
AU - Fisher, Matthew B.
T2 - JOURNAL OF BIOMECHANICAL ENGINEERING-TRANSACTIONS OF THE ASME
AB - Finite element analysis is a useful tool to model growth of biological tissues and predict how growth can be impacted by stimuli. Previous work has simulated growth using node-based or element-based approaches, and this implementation choice may influence predicted growth, irrespective of the applied growth model. This study directly compared node-based and element-based approaches to understand the isolated impact of implementation method on growth predictions by simulating growth of a bone rudiment geometry, and determined what conditions produce similar results between the approaches. We used a previously reported node-based approach implemented via thermal expansion and an element-based approach implemented via osmotic swelling, and we derived a mathematical relationship to relate the growth resulting from these approaches. We found that material properties (modulus) affected growth in the element-based approach, with growth completely restricted for high modulus values relative to the growth stimulus, and no restriction for low modulus values. The node-based approach was unaffected by modulus. Node- and element-based approaches matched marginally better when the conversion coefficient to relate the approaches was optimized based on the results of initial simulations, rather than using the theoretically predicted conversion coefficient (median difference in node position 0.042 cm versus 0.052 cm, respectively). In summary, we illustrate here the importance of the choice of implementation approach for modeling growth, provide a framework for converting models between implementation approaches, and highlight important considerations for comparing results in prior work and developing new models of tissue growth.
DA - 2022/1/1/
PY - 2022/1/1/
DO - 10.1115/1.4051661
VL - 144
IS - 1
SP -
SN - 1528-8951
ER -
TY - JOUR
TI - High piezoelectricity after field cooling AC poling in temperature stable ternary single crystals manufactured by continuous-feeding Bridgman method
AU - Luo, Cong
AU - Karaki, Tomoaki
AU - Wang, Zhuangkai
AU - Sun, Yiqin
AU - Yamashita, Yohachi
AU - Xu, Jiayue
T2 - JOURNAL OF ADVANCED CERAMICS
AB - Abstract After field cooling (FC) alternating current poling (ACP), we investigated the dielectric and piezoelectric properties of [001] pc -oriented 0.24Pb(In 1/2 Nb 1/2 )O 3 (PIN)-0.46Pb(Mg 1/3 Nb 2/3 )O 3 (PMN)-0.30PbTiO3 (PT) (PIMN-0.30PT) single crystals (SCs), which were manufactured by continuous-feeding Bridgman (CF BM) within morphotropic phase boundary (MPB) region. By ACP with 4 kV rms /cm from 100 to 70 °C, the PIMN-0.30PT SC attained high dielectric permittivity (ε 33 T /ε 0 ) of 8330, piezoelectric coefficient ( d 33 ) of 2750 pC/N, bar mode electromechanical coupling factor k 33 of 0.96 with higher phase change temperature ( T pc ) of 103 °C, and high Curie temperature ( T C ) of 180 °C. These values are the highest ever reported as PIMN- x PT SC system with T pc > 100 °C. The enhancement of these properties is attributed to the induced low symmetry multi-phase supported by phase analysis. This work indicates that FC ACP is a smart and promising method to enhance piezoelectric properties of relaxor-PT ferroelectric SCs including PIMN- x PT, and provides a route to a wide range of piezoelectric device applications.
DA - 2022/1//
PY - 2022/1//
DO - 10.1007/s40145-021-0490-1
VL - 11
IS - 1
SP - 57-65
SN - 2227-8508
KW - field cooling (FC) alternating current poling (ACP)
KW - PIMN-0
KW - 30PT
KW - high piezoelectricity
ER -
TY - JOUR
TI - Special Issue: The Behavior of Crystalline Materials: In Honor of Professor Hussein Zbib
AU - Field, David
AU - Garmestani, Hamid
AU - Khraishi, Tariq
AU - Zikry, Mohammed
T2 - JOURNAL OF ENGINEERING MATERIALS AND TECHNOLOGY-TRANSACTIONS OF THE ASME
AB - This special issue of the ASME Journal of the Engineering Materials and Technology is dedicated to the memory of our friend and colleague, Professor Hussein Zbib, who passed away in February 2020. Hussein was a past editor of this journal and was an internationally recognized research leader and an innovator in numerous aspects of mechanics of materials, such as dislocation dynamics, plasticity, and irradiated materials. The articles in this special issue, through the different contributions of his collaborators, colleagues, students, and friends, truly reflect the different research areas he impacted. Furthermore, these contributions underscore how his research interests, collaborations, and achievements fundamentally influenced the experimental and modeling accomplishments of the contributing authors.Hussein was a Professor in the School of Mechanical and Materials Engineering at Washington State University since 1988. As a director of the Computational Mechanics and Materials Science Laboratory, he conducted research in the field of multiscale theoretical modeling and predictions of the thermo-mechanical behavior of advanced materials. He developed models and theories used by materials scientists and engineers throughout the world, and his research significantly improved and elevated the fundamental understanding of the behavior of metals, alloys, and composites at different physical scales.His research group, for instance, developed models to simulate the behavior of a wide array of materials that are exposed to high doses of radiation. It was well known that such materials can deform and fail, but the mechanics and defect behavior were not well understood until Hussein and his coworkers developed a new class of computational tools based on innovative formulations related to dislocation dynamics. This was a crucial breakthrough, since dislocation dynamics is essentially now recognized as an established link between atomistic and continuum approaches.Hussein published more than 250 technical articles in leading journals, edited 12 books, and presented hundreds of invited talks and seminars. Over his career, he supervised and mentored more than 30 masters and doctoral students, six postdoctoral fellows, 11 visiting scholars, and 15 undergraduate research assistants. Many of his students went on to become internationally recognized researchers and leaders in academia, in industry, and at national laboratories.Hussein was a fellow of the American Association for the Advancement of Science and the ASME as well as an executive member of the Lebanese Academy of Science. He was a recipient of the 2010 Khan International Award for outstanding contribution to the field of plasticity. He also received research excellence awards from the Voiland College of Engineering and Architecture in 1994 and 2015 and from the School of Mechanical and Materials Engineering in 2000 at Washington State University. He was named a Regents Professor, the university's highest faculty title, in 2018. He also served as the director of the School of MME from 2003 to 2011. During his tenure as a school director, he played a significant role in expanding the faculty size, research expenditures, and private donations, and fostering partnerships with industries and national laboratories, such that the School is now recognized as a leading national mechanical engineering and materials science department.Hussein was born in Beirut, Lebanon, to Mustapha and Sahjouna Zbib, and his parents were from South Lebanon. He completed his schooling in Beirut, graduating from Aamlye Technical College. Zbib received his bachelor, masters, and Ph.D. in Mechanical Engineering and Engineering Mechanics from Michigan Technological University. He married Marcia Ann Rowe in Hancock, MI, on July 12, 1986, and in 1988, they moved to Pullman when Zbib accepted a position at WSU.Hussein enjoyed being with family and friends. He enjoyed cooking and dancing, and he and his wife Marcia were active in both the Palouse dance club and gourmet club. Zbib also enjoyed golfing, fishing, boating, reading, cross country skiing, table tennis, tennis, going to fine dining restaurants, and spending time at the gym exercising and swimming. Together he and his wife Marcia enjoyed traveling throughout the world.Hussein is survived by his wife Marcia, mother Sahjouna Zbib, two brothers Ali and Bilal Zbib, three sisters Fadia, Hana, and Iman Zbib, and many nieces and nephews. He was preceded in death by his father Mustapha Zbib, brother Hassan Zbib; and two sisters Ferial and Sanaa Zbib.Hussein was the model for a research innovator and an academic leader. All of us are missing Hussein; we will never forget him, his wisdom, his easy smile, and the twinkle in his eye. His spirit will always be with us as a guiding light in our lives.
DA - 2022/1/1/
PY - 2022/1/1/
DO - 10.1115/1.4052487
VL - 144
IS - 1
SP -
SN - 1528-8889
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85144510088&partnerID=MN8TOARS
ER -
TY - JOUR
TI - Thermomechanical Microstructural Predictions of Fracture Nucleation of Zircaloy-4 Alloys With delta and e Hydride Distributions
AU - Mohamed, I.
AU - Hasan, T.
AU - Zikry, M. A.
T2 - JOURNAL OF ENGINEERING MATERIALS AND TECHNOLOGY-TRANSACTIONS OF THE ASME
AB - Abstract A crystalline dislocation-density formulation that was incorporated with a nonlinear finite-element (FE) method was utilized to understand and to predict the thermomechanical behavior of an hexagonal closest packed (h.c.p.) zircaloy system with hydrides with either face-centered cubic (f.c.c.) or body-centered cubic (b.c.c.) hydrides. This formulation was then used with a recently developed fracture methodology that is adapted for finite inelastic strains and multiphase crystalline systems to understand how different microstructurally based fracture modes nucleate and propagate. The interrelated microstructural characteristics of the different crystalline hydride and matrix phases with the necessary orientation relationships (ORs) have been represented, such that a detailed physical understanding of fracture nucleation and propagation can be predicted for the simultaneous thermomechanical failure modes of hydride populations and the matrix. The effects of volume fraction, morphology, crystalline structure, and orientation and distribution of the hydrides on simultaneous and multiple fracture modes were investigated for radial, circumferential, and mixed distributions. Another key aspect was accounting for temperatures changes due to the effects of thermal conduction and dissipated plastic work and their collective effects on fracture. For hydrided aggregates subjected to high temperatures, thermal softening resulted in higher ductility due to increased dislocation-density activity, which led to higher shear strain accumulation and inhibited crack nucleation and growth. The predictions provide validated insights into why circumferential hydrides are more fracture-resistant than radial hydrides for different volume fractions and thermomechanical loading conditions.
DA - 2022/1/1/
PY - 2022/1/1/
DO - 10.1115/1.4051687
VL - 144
IS - 1
SP -
SN - 1528-8889
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85127542533&partnerID=MN8TOARS
KW - zirconium h
KW - c
KW - p
KW - matrix
KW - fracture nucleation
KW - radial and circumferential hydrides
KW - crystalline orientations
KW - mechanical behavior
KW - microstructure property relationships
KW - plastic behavior
ER -
TY - JOUR
TI - Experiment-Based Modeling of Turbulent Flames with Inhomogeneous Inlets
AU - Ranade, Rishikesh
AU - Echekki, Tarek
AU - Masri, Assaad R.
T2 - Flow, Turbulence and Combustion
DA - 2022/4//
PY - 2022/4//
DO - 10.1007/s10494-021-00304-8
UR - https://doi.org/10.1007/s10494-021-00304-8
KW - Data-based modeling
KW - Kernel density estimation
KW - Principal component analysis
KW - Artificial neural networks
ER -
TY - JOUR
TI - Ultrasonic frequency response of fiber Bragg grating under direct and remote adhesive bonding configurations
AU - Navratil, Andrew
AU - Wee, Junghyun
AU - Peters, Kara
T2 - MEASUREMENT SCIENCE AND TECHNOLOGY
AB - Abstract Ultrasonic inspection based structural health monitoring is a powerful technique for damage detection in a structure. Ultrasonic waves are often excited at different frequencies to detect damages of different sizes, therefore understanding the frequency response of the sensor can be used to optimize the sensor performance. Fiber Bragg gratings (FBGs) are widely used for this ultrasound collection. The sensitivity of FBGs to a particular ultrasonic frequency is a function of the FBG length and the ultrasonic wavelength. Recently the authors demonstrated that its ultrasound sensitivity is improved for some conditions when the FBG is bonded at a distance away from the adhesive bond, referred to as remote bonding. However, the frequency response of this configuration has not been studied. Therefore, in this paper we measure and compare the ultrasonic frequency responses between a conventional directly bonded FBG and remotely bonded FBG. In theory, the FBG sensitivity varies as a function of ultrasound wavelength-to-grating length ( λ / L ) ratio. Therefore, for this experimental study, we maintain L constant and vary λ by changing the frequency of the input ultrasonic waves. We demonstrate that there is a region, below a cut-off values of λ / L , for which the remotely bonded FBG output has a higher sensitivity to the Lamb wave amplitude than the directly bonded FBG. The exact value of this λ / L cut-off depends on the mechanical properties of the structure, the windowing of the input Lamb wave, and the FBG properties. We also demonstrate that windowing the Lamb wave excitation signal has a similar affect to apodizing the FBG sensor in modifying the sensitivity response curve.
DA - 2022/1//
PY - 2022/1//
DO - 10.1088/1361-6501/ac2fea
VL - 33
IS - 1
SP -
SN - 1361-6501
KW - structural health monitoring
KW - non-destructive evaluation
KW - ultrasonic inspection
KW - optical fiber sensor
KW - fiber Bragg grating
ER -
TY - JOUR
TI - Object Recognition via Evoked Sensory Feedback during Control of a Prosthetic Hand
AU - Vargas, Luis
AU - Huang, He
AU - Zhu, Yong
AU - Hu, Xiaogang
T2 - IEEE ROBOTICS AND AUTOMATION LETTERS
AB - Haptic and proprioceptive feedback is critical for sensorimotor integration when we use our hand to perform daily tasks. Here, we evaluated how externally evoked haptic and proprioceptive feedback and myoelectric control strategies affected the recognition of object properties when participants controlled a prosthetic hand. Fingertip haptic sensation was elicited using a transcutaneous nerve stimulation grid to encode the prosthetic's fingertip forces. An array of tactors elicited patterned vibratory stimuli to encode tactile-proprioceptive kinematic information of the prosthetic finger joint. Myoelectric signals of the finger flexor and extensor were used to control the position or velocity of joint angles of the prosthesis. Participants were asked to perform object property (stiffness and size) recognition, by controlling the prosthetic hand with concurrent haptic and tactile-proprioceptive feedback. With the evoked feedback, intact and amputee participants recognized the object stiffness and size at success rates ranging from 50% to 100% in both position and velocity control with no significant difference across control schemes. Our findings show that evoked somatosensory feedback in a non-invasive manner can facilitate closed-loop control of the prosthetic hand and allowed for simultaneous recognition of different object properties. The outcomes can facilitate our understanding on the role of sensory feedback during bidirectional human-machine interactions, which can potentially promote user experience in object interactions using prosthetic hands.
DA - 2022/1//
PY - 2022/1//
DO - 10.1109/LRA.2021.3122897
VL - 7
IS - 1
SP - 207-214
SN - 2377-3766
KW - Haptic and proprioceptive sensation
KW - transcutaneous nerve stimulation
KW - vibrotactile stimulation
KW - stiffness recognition
KW - size recognition
ER -
TY - JOUR
TI - Dielectric and mechanical properties of hypersonic radome materials and metamaterial design: A review
AU - Kenion, Taylor
AU - Yang, Ni
AU - Xu, Chengying
T2 - JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
AB - This review paper examines ten current ceramic radome materials under research and development and provides a comprehensive overview of available high temperature and high frequency data from literature. An examination of metamaterials for radio-frequency transparent radomes is given and our preliminary experimental results of a high-temperature metamaterial design are presented. The next-generation hypersonic vehicles’ radome temperatures will exceed 1000℃ and speeds will exceed Mach 5. An ideal radome material will have a high flexural strength, low dielectric constant and loss tangent, and high resistance to thermal shock and corrosion. The microstructural effect on the dielectric and mechanical properties and the effects of environmental factors such as rain are discussed. The impact of metamaterial structure on key radome factors such as boresight error, gain, and polarization is examined. After examining the associated benefits with the use of metamaterials, our preliminary results for a potential high-temperature metamaterial design are presented.
DA - 2022/1//
PY - 2022/1//
DO - 10.1016/j.jeurceramsoc.2021.10.006
VL - 42
IS - 1
SP - 1-17
SN - 1873-619X
KW - Radome
KW - Hypersonic
KW - Ceramic
KW - High temperature
KW - Review
KW - Metamaterial
ER -
TY - JOUR
TI - Investigation of deep learning methods for efficient high-fidelity simulations in turbulent combustion
AU - Gitushi, Kevin M.
AU - Ranade, Rishikesh
AU - Echekki, Tarek
T2 - COMBUSTION AND FLAME
AB - Turbulent combustion modeling often faces a trade-off between the so-called flamelet-like models and PDF-like models. Flamelet-like models, are characterized by a choice of a limited set of prescribed moments, which are transported to represent the manifold of the composition space and its statistics. PDF-like approaches are designed to directly evaluate the closure terms associated with the nonlinear chemical source terms in the energy and species equations. They generate data on the fly, which can be used to accelerate the simulation of PDF-like based models. Establishing key ingredients for implementing acceleration schemes for PDF-like methods by constructing flamelet-like models on the fly can potentially result in computational saving while maintaining the ability to resolve closure terms. These ingredients are investigated in this study. They include a data-based dimensional reduction of the composition space to a low-dimensional manifold using principal component analysis (PCA). The principal components (PCs) serve as moments, which characterize the manifold; and conditional means of the thermo-chemical scalars are evaluated in terms of these PCs. A second ingredient involves adapting a novel deep learning framework, DeepONet, to construct joint PCs’ PDFs as alternative methods to presumed shapes common in flamelet-like approaches. We also investigate whether the rotation of the PCs into independent components (ICs) can improve their statistical independence. The combination of these ingredients is investigated using experimental data based on the Sydney turbulent nonpremixed flames with inhomogeneous inlets. The combination of constructed PDFs and conditional mean models are able to adequately reproduce unconditional statistics of thermo-chemical scalars, and establish acceptable statistical independence between the PCs, which simplify further the modeling of the joint PCs’ PDFs.
DA - 2022/2//
PY - 2022/2//
DO - 10.1016/j.combustflame.2021.111814
VL - 236
SP -
SN - 1556-2921
UR - https://doi.org/10.1016/j.combustflame.2021.111814
KW - DeepONet
KW - Kernel density estimation
KW - Principal component analysis
KW - Independent component analysis
ER -
TY - JOUR
TI - Direct measurement of rate-dependent mode I and mode II traction-separation laws for cohesive zone modeling of laminated glass
AU - Poblete, Felipe R.
AU - Mondal, Kunal
AU - Ma, Yinong
AU - Dickey, Michael D.
AU - Genzer, Jan
AU - Zhu, Yong
T2 - COMPOSITE STRUCTURES
AB - This paper reports a combined experimental-modeling study on the adhesion at glass/poly(vinyl butyral) (PVB) interfaces. PVB is a critical component in laminated glasses that provides impact resistance and prevents spallation in the event of glass breakage. We characterize the mode I (normal) and mode II (shear) interfacial fracture behaviors in glass/PVB/glass laminates and obtained independent cohesive (traction–separation) laws for the two modes. We observe a pronounced rate dependence of both traction-separation laws. Specifically, with increasing loading rate, the interfacial stiffness, the peak stress, and the fracture toughness increase while the critical opening or shear displacement decreases. These measured traction-separation laws are used as inputs in finite element analysis to predict the mechanical behavior of the peel test, which agrees reasonably well with the experimental results. Finite element analysis of a glass laminate subjected to impact loading demonstrates how the measured interfacial properties can be used to predict the mechanical behavior and failure of laminated glass.
DA - 2022/1/1/
PY - 2022/1/1/
DO - 10.1016/j.compstruct.2021.114759
VL - 279
SP -
SN - 1879-1085
KW - Glass
KW - PVB
KW - Interfacial mechanics
KW - Cohesive zone modeling
KW - Adhesion
KW - Shear strength
ER -