TY - CHAP TI - III-Nitride LEDs with photonic crystal structures AU - Wierer, J. J. AU - Krames, M. R. AU - Epler, J. E. AU - Gardner, N. F. AU - Wendt, J. R. AU - Sigalas, M. M. AU - Brueck, S. R. J. AU - Li, D. AU - Shagam, M. T2 - Light-Emitting Diodes: Research, Manufacturing, and Applications IX A2 - Stockman, S. A. A2 - Yao, H. W. A2 - Schubert, E. F. AB - Electrical operation of III-Nitride light emitting diodes (LEDs) with photonic crystal structures is demonstrated. Employing photonic crystal structures in III-Nitride LEDs is a method to increase light extraction efficiency and directionality. The photonic crystal is a triangular lattice formed by dry etching into the III-Nitride LED. A range of lattice constants is considered (a ~ 270 - 340nm). The III-Nitride LED layers include a tunnel junction providing good lateral current spreading without a semi-absorbing metal current spreader as is typically done in conventional III-Nitride LEDs. These photonic crystal III-Nitride LED structures are unique because they allow for carrier recombination and light generation proximal to the photonic crystal (light extraction area) yet displaced from the absorbing metal contact. The photonic crystal Bragg scatters what would have otherwise been guided modes out of the LED, increasing the extraction efficiency. The far-field light radiation patterns are heavily modified compared to the typical III-Nitride LED’s Lambertian output. The photonic crystal affects the light propagation out of the LED surface, and the radiation pattern changes with lattice size. LEDs with photonic crystals are compared to similar III-Nitride LEDs without the photonic crystal in terms of extraction, directionality, and emission spectra. PY - 2005/// DO - 10.1117/12.591218 VL - 5739 SP - 102-107 PB - SE - UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000228826900013&KeyUID=WOS:000228826900013 ER - TY - JOUR TI - Polarization anisotropy in the electroluminescence of m-plane InGaN-GaN multiple-quantum-well light-emitting diodes AU - Gardner, N. F. AU - Kim, J. C. AU - Wierer, J. J. AU - Shen, Y. C. AU - Krames, M. R. T2 - Applied Physics Letters AB - InGaN – GaN multiple-quantum-well light-emitting diodes were fabricated on (101¯0) m plane GaN films grown on (101¯0) m plane 4H–SiC substrates. The [0001] axis of the epitaxial film is parallel to the [0001] axis of the substrate. The surface is striated, with features running perpendicular to the c axis and a maximum surface height difference of 45nm. Electroluminescence shows strong polarization anisotropy, with 7× more light emitted with polarization perpendicular to the c axis compared to parallel to the c axis. An Ahrrenius fit of the polarization ratio indicates that there is a 49meV difference in the energy gap between the two polarization states. This suggests that a high polarization ratio can be maintained at the high temperatures (>150°C) and drive current densities required for high-power light-emitting diode applications. DA - 2005/// PY - 2005/// DO - 10.1063/1.1875765 VL - 86 IS - 11 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000228050700001&KeyUID=WOS:000228050700001 ER - TY - JOUR TI - Science of odor as a potential health issue AU - Schiffman, S.S. AU - Williams, C.M. T2 - Journal of Environmental Quality AB - Historically, unpleasant odors have been considered warning signs or indicators of potential risks to human health but not necessarily direct triggers of health effects. However, citizen complaints to public health agencies suggest that odors may not simply serve as a warning of potential risks but that odor sensations themselves may cause health symptoms. Mal-odors emitted from large animal production facilities and wastewater treatment plants, for example, elicit complaints of eye, nose, and throat irritation, headache, nausea, diarrhea, hoarseness, sore throat, cough, chest tightness, nasal congestion, palpitations, shortness of breath, stress, drowsiness, and alterations in mood. There are at least three mechanisms by which ambient odors may produce health symptoms. First, symptoms can be induced by exposure to odorants (compounds with odor properties) at levels that also cause irritation or other toxicological effects. That is, irritation--rather than the odor--is the cause of the health symptoms, and odor (the sensation) simply serves as an exposure marker. Second, health symptoms from odorants at non-irritant concentrations can be due to innate (genetically coded) or learned aversions. Third, symptoms may be due to a co-pollutant (such as endotoxin) that is part of an odorant mixture. Objective biomarkers of health symptoms must be obtained, however, to determine if health complaints constitute health effects. One industry that is receiving much attention, worldwide, related to this subject is concentrated animal production agriculture. Sustainability of this industry will likely necessitate the development of new technologies to mitigate odorous aerial emissions. Examples of such "environmentally superior technologies" (EST) developed under the initiative sponsored through agreements between the Attorney General of North Carolina and Smithfield Foods and Premium Standard Farms are described. DA - 2005/// PY - 2005/// DO - 10.2134/jeq2005.0129a VL - 34 SP - 129–138 ER - TY - CONF TI - Odor dispersion modeling from swine operations with conventional and alternative waste treatment technologies AU - Schiffman, S.S. AU - Graham, B.G. AU - DuBose, P.A. AU - Williams, C.M. T2 - 2005 Animal Waste Management Symposium: The Development of Alternative Technologies for the Processing and Use of Animal Waste C2 - 2005/// C3 - Proceedings of the 2005 Animal Waste Management Symposium: The Development of Alternative Technologies for the Processing and Use of Animal Waste CY - Raleigh, NC DA - 2005/// PY - 2005/// ER - TY - JOUR TI - Symptomatic Effects of Exposure to Diluted Air Sampled from a Swine Confinement Atmosphere on Healthy Human Subjects AU - Schiffman, Susan S. AU - Studwell, Clare E. AU - Landerman, Lawrence R. AU - Berman, Katherine AU - Sundy, John S. T2 - Environmental Health Perspectives AB - Aerial emissions from a swine house at North Carolina State University's field laboratory were diluted to a level that could occur at varying distances downwind from a confined animal feeding operation (CAFO) both within and beyond the property line, and these emissions were delivered to an environmental exposure chamber. The study design consisted of two 1-hr sessions, one in which 48 healthy human adult volunteers were exposed to diluted swine air and another in which they were exposed to clean air (control). Objective measures of blood pressure, temperature, heart rate, respiratory rate, lung function, nasal inflammation, secretory immunity, mood, attention, and memory were correlated with objective measures of air quality. Ratings of perceived (self-reported) health symptoms were also obtained. The mean levels of airborne constituents in the swine air condition were hydrogen sulfide (24 ppb), ammonia (817 ppb), total suspended particulates (0.0241 mg/m3), endotoxin (7.40 endotoxin units/m3), and odor (57 times above odor threshold). No statistical differences on objective measures of physical symptoms, mood, or attention resulted from the 1-hr exposure to swine emissions in the environmental chamber when compared with clean air for healthy human volunteers. However, subjects were 4.1 (p = 0.001) times more likely to report headaches, 6.1 (p = 0.004) times more likely to report eye irritation, and 7.8 (p = 0.014) times more likely to report nausea in the swine air (experimental) condition than in the control condition. These results indicate that short-term exposure in an environmental chamber to malodorous emissions from a swine house at levels expected downwind can induce clinically important symptoms in healthy human volunteers. DA - 2005/5// PY - 2005/5// DO - 10.1289/ehp.6814 VL - 113 IS - 5 SP - 567-576 J2 - Environ Health Perspect LA - en OP - SN - 0091-6765 1552-9924 UR - http://dx.doi.org/10.1289/ehp.6814 DB - Crossref ER - TY - JOUR TI - Implementation of Breiman’s random forest machine learning algorithm AU - Livingston, Frederick T2 - ECE591Q Machine Learning Journal Paper DA - 2005/// PY - 2005/// SP - 1-13 ER - TY - JOUR TI - Implementation of Breiman's Random Forest Machine Learning Algorithm ECE591Q Machine Learning Journal Paper AU - Livingston, Frederick DA - 2005/// PY - 2005/// ER - TY - JOUR TI - Bone Tissue Scaffold in PCL AU - Jeng, L AU - Livingston, F T2 - Bone DA - 2005/// PY - 2005/// ER - TY - CONF TI - Implementing Breiman’s random forest algorithm into Weka AU - Livingston, Frederick C2 - 2005/// C3 - ECE591Q machine learning conference papers DA - 2005/// VL - 27 SP - 1-5 ER - TY - CONF TI - Wire-Delay Reduction Analysis of a 3-Tier, 8-Point Fast Fourier Transform 3D-IC AU - Davis, W.R. AU - Hua, H. AU - Sule, A. AU - Mineo, C. AU - Melamed, S. AU - Steer, M. AU - Franzon, P.D. T2 - VLSI Multilevel Interconnection (VMIC) Conference C2 - 2005/10// C3 - VLSI Multilevel Interconnection (VMIC) Conference DA - 2005/10// PY - 2005/10// SP - 474–479 ER - TY - CONF TI - Pre-route Net Classing for Crosstalk Avoidance AU - Hua, H. AU - Sule, A. AU - Mineo, C. AU - Davis, W.R. T2 - Cadence Designer Network Live Conference (CDNLive) C2 - 2005/9/12/ CY - San Jose, CA DA - 2005/9/12/ PY - 2005/9/12/ ER - TY - CONF TI - OpenAccess Tools for 3D Integration AU - Davis, W.R. T2 - OpenAccess Conference C2 - 2005/11/10/ CY - San Jose, CA DA - 2005/11/10/ PY - 2005/11/10/ ER - TY - JOUR TI - Analysis and Training of Compensation Neural Model for System Dynamics Modeling AU - Tipsuwan, Y. AU - Chow, M.-Y. T2 - Journal of Research in Engineering and Technology DA - 2005/// PY - 2005/// VL - 2 IS - 1 SP - 28–43 ER - TY - JOUR TI - Monolith and Partition Schemes with LDA and Neural Networks as Detector Units for Induction Motor Broken Rotor Bar Fault Detection AU - Ayhan, B. AU - Chow, M.-Y. AU - Song, M.-H. T2 - KIEE International Transactions on Electrical Machinery and Energy Conversion Systems DA - 2005/6/1/ PY - 2005/6/1/ VL - 5 IS - 2 SP - 103-110 ER - TY - CONF TI - The feasibility of on-chip interconnection using antennas AU - O, K.K. AU - Kim, K. AU - Floyd, B. AU - Mehta, J. AU - Yoon, H. AU - Hung, C.-M. AU - Bravo, D. AU - Dickson, T. AU - Guo, X. AU - Li, R. AU - Trichy, N. AU - Caserta, J. AU - Bomstad, W. AU - Branch, J. AU - Yang, D.-J. AU - Bohorquez, J. AU - Chen, J. AU - Seok, E.-Y. AU - Gao, L. AU - Sugavanam, A. AU - Lin, J.-J. AU - Yu, S. AU - Cao, C. AU - Hwang, M.-H. AU - Ding, Y.-P. AU - Hwang, S.-H. AU - Wu, H. AU - Zhang, N. AU - Brewer, J.E. C2 - 2005/// C3 - IEEE/ACM International Conference on Computer-Aided Design, Digest of Technical Papers, ICCAD DA - 2005/// DO - 10.1109/ICCAD.2005.1560204 VL - 2005 SP - 976-981 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33751428417&partnerID=MN8TOARS ER - TY - CONF TI - Progress toward a low-cost millimeter-wave silicon radio AU - Reynolds, S.K. AU - Floyd, B.A. AU - Pfeiffer, U.R. AU - Beukema, T.J. AU - Zwick, T. AU - Grzyb, J. AU - Liu, D. AU - Gaucher, B.P. AB - This paper discusses the circuits, packaging, and antennas needed to realize a low-cost millimeter-wave transceiver with integrated antenna in silicon technology. The principal application envisioned is in high-speed 60-GHz wireless networks, but the concepts may be applicable to other products as well, such as 77-GHz radar sensors. Circuit results are presented for both 60 and 77 GHz, including an LNA, a highly-integrated direct downconverter, a mixer for a superheterodyne receiver, and a power amplifier. Packaging issues which arise at millimeter-wave frequencies are discussed, and a packaging approach involving a Si IC and a planar antenna in the same package is described. Measurement results for a planar Vivaldi antenna are presented as an example. C2 - 2005/// C3 - Proceedings of the Custom Integrated Circuits Conference DA - 2005/// DO - 10.1109/CICC.2005.1568731 VL - 2005 SP - 563-570 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33847142322&partnerID=MN8TOARS ER - TY - CONF TI - Implementing Digital Power Control In Automotive Alternators AU - Thondapu, C. AU - Hopkins, D.C. AU - Holguin, G. T2 - Digital Power Forum C2 - 2005/// CY - Boston MA DA - 2005/// PY - 2006/9/12/ ER - TY - JOUR TI - Flip chip solder joint failure modes AU - Basaran, C. AU - Ye, H. AU - Hopkins, D.C. AU - Frear, D. AU - Lin, J.K. T2 - Advanced Packaging DA - 2005/10// PY - 2005/10// VL - 14 IS - 10 SP - 14–19 ER - TY - CONF TI - Modeling deformation in microelectronics BGA solder joints under high current density. Part I. Simulation and testing AU - Ye, Hua AU - Basaran, C. AU - Hopkins, D.C. AU - Lin, Minghui T2 - 2005 55th Electronic Components and Technology Conference AB - In this paper, Moire interferometry technique is used to measure the in-situ displacement evolution of lead-free solder joint under electric current stressing. Large deformation was observed in solder joint under high density (10/sup 4/A/cm/sup 2/) current stressing. The deformation was found to be due to electromigration in the solder joint. An electromigration constitutive model is developed to simulate deformation of lead-free solder joint under current stressing. The simulation predicts reasonably close displacements results to Moire interferometry experimental results in both spatial distribution and time history evolution, which indicates that the electromigration model is reasonably good for predicting the mechanical behavior of lead-free solder alloy under electric current stressing. This is the first part of the papers reporting the deformation of solder joint under current stressing. More experimental results are reported in the second paper. C2 - 2005/7/27/ C3 - Proceedings Electronic Components and Technology, 2005. ECTC '05. DA - 2005/7/27/ DO - 10.1109/ectc.2005.1441975 PB - IEEE SN - 0780389069 UR - http://dx.doi.org/10.1109/ectc.2005.1441975 DB - Crossref ER - TY - JOUR TI - Languages and compilers for parallel computing AU - Tseng, Bill Pugh Chau-Wen DA - 2005/// PY - 2005/// ER - TY - CONF TI - Tasking with out-of-order spawn in TLS chip multiprocessors: Microarchitecture and compilation AU - Renau, Jose AU - Tuck, James AU - Liu, Wei AU - Ceze, Luis AU - Strauss, Karin AU - Torrellas, Josep C2 - 2005/// C3 - Proceedings of the 19th Annual International conference on Supercomputing DA - 2005/// SP - 179-188 ER - TY - JOUR TI - SESC simulator, January 2005 AU - Renau, Jose AU - Fraguela, Basilio AU - Tuck, James AU - Liu, Wei AU - Prvulovic, Milos AU - Ceze, Luis AU - Sarangi, Smruti AU - Sack, Paul AU - Strauss, Karin AU - Montesinos, Pablo DA - 2005/// PY - 2005/// ER - TY - JOUR TI - Modeling and optimization of single-element bulk SiGe thin-film coolers AU - Vashaee, Daryoosh AU - Christofferson, James AU - Zhang, Yan AU - Shakouri, Ali AU - Zeng, Gehong AU - LaBounty, Chris AU - Fan, Xiaofeng AU - Piprek, Joachim AU - Bowers, John E. AU - Croke, Edward T2 - Microscale Thermophysical Engineering AB - Abstract Abstract Modeling and optimization of bulk SiGe thin-film coolers are described. Thin-film coolers can provide large cooling power densities compared to commercial thermoelectrics. Thin-film SiGe coolers have been demonstrated with maximum cooling of 4°C at room temperature and with cooling power density exceeding 500 W/cm2. Important parameters in the design of such coolers are investigated theoretically and are compared with experimental data. Thermoelectric cooling, joule heating, and heat conduction are included in the model as well as non-ideal effects such as contact resistance, geometrical effects, and three-dimensional thermal and electrical spreading resistance of the substrate. Simulations exhibit good agreement with experimental results for bulk Si and SiGe thin-film coolers. It turned out that in many spot cooling applications using two n- and p-elements electrically in series and thermally in parallel does not give significant improvement over single leg elements. This is in contrast to conventional thermoelectric modules and is due to the aspect ratio and special geometry of thin film coolers. With optimization of SiGe thin-film cooler, simulations predict it can provide over 16°C with cooling power density of over 2000 W/cm2. Acknowledgments This work was supported by the DARPA HERETIC program and the Packard Foundation. DA - 2005/2/23/ PY - 2005/2/23/ DO - 10.1080/10893950590913459 VL - 9 IS - 1 SP - 99-118 SN - 1089-3954 1091-7640 UR - http://dx.doi.org/10.1080/10893950590913459 ER - TY - JOUR TI - Does Shafer-Landau Have a Problem with Supervenience? AU - Mabrito, Robert T2 - Philosophical Studies DA - 2005/11// PY - 2005/11// DO - 10.1007/S11098-005-2163-2 VL - 126 IS - 2 SP - 297-311 J2 - Philos Stud LA - en OP - SN - 0031-8116 1573-0883 UR - http://dx.doi.org/10.1007/S11098-005-2163-2 DB - Crossref ER - TY - CONF TI - Gallium Oxide as a host for rare earth elements AU - Muth, J.F. AU - Gollakota, P. AU - Dhawan, A. AU - Porter, H.L. AU - Saripalli, Y.N. AU - Lunardi, L.M. C2 - 2005/// C3 - Materials Research Society Symposium Proceedings DA - 2005/// DO - 10.1557/proc-866-v6.2 VL - 866 SP - 177-182 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-30544448982&partnerID=MN8TOARS ER - TY - CONF TI - Quantization on the grassmann manifold: Applications to precoded mimo wireless systems AB - This paper studies the problem of quantization of a source that lives on the complex Grassmann manifold. The special structure of the Grassmann manifold and the distortion measures that are defined on it differentiates this problem from the traditional problem of vector quantization in Euclidean spaces. Assuming a uniform source distribution along with a distortion based on chordal distance, codebook design algorithms are mentioned and rate distortion tradeoffs are studied. The expected distortion for such a quantizer is approximately characterized. These results are then applied to the performance analysis of a multiple antenna wireless communication system. C2 - 2005/// C3 - ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings DA - 2005/// DO - 10.1109/ICASSP.2005.1416481 VL - V UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33646786793&partnerID=MN8TOARS ER - TY - JOUR TI - Switching between diversity and multiplexing in MIMO systems T2 - IEEE Transactions on Communications AB - Multiple-input multiple-output (MIMO) wireless communication systems can offer high data rates through spatial multiplexing or substantial diversity using transmit diversity. In this letter, switching between spatial multiplexing and transmit diversity is proposed as a simple way to improve the diversity performance of spatial multiplexing. In the proposed approach, for a fixed rate, either multiplexing or diversity is chosen based on the instantaneous channel state and the decision is conveyed to the transmitter via a low-rate feedback channel. The minimum Euclidean distance at the receiver is computed for spatial multiplexing and transmit diversity and is used to derive the selection criterion. Additionally, the Demmel condition number of the matrix channel is shown to provide a sufficient condition for multiplexing to outperform diversity. Monte Carlo simulations demonstrate improvement over either multiplexing or diversity individually in terms of bit error rate. DA - 2005/// PY - 2005/// DO - 10.1109/TCOMM.2005.849774 VL - 53 IS - 6 SP - 962-972 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-22144485992&partnerID=MN8TOARS KW - multiple-input multiple-output (MIMO) systems KW - space-time coding KW - transmit diversity ER - TY - JOUR TI - Simulation of MIMO channel capacity with antenna polarization diversity T2 - IEEE Transactions on Wireless Communications AB - A simulation study of the channel capacity of a multiple-input multiple-output (MIMO) antenna system exploiting multiple polarizations is carried out. We focus on a simple yet realistic trimonopole antenna structure, taking into account all the mutual coupling and casing effects using the computational electromagnetics solver-numerical electromagnetics code. Simulation results show that, with a special transmit geometry, using the collocated trimonopole antennas at a size-constrained receiver can offer channel capacity that approaches the capacity of an uncorrelated MIMO Rayleigh channel. In addition, it is shown that the capacity increase is mainly attributed to polarization diversity instead of pattern diversity. Furthermore, we find that the mutual coupling and casing effects in the trimonopole system can actually provide a large capacity increase with less constraint on the antenna configurations than the idealized tridipole system. DA - 2005/// PY - 2005/// DO - 10.1109/TWC.2005.850318 VL - 4 IS - 4 SP - 1869-1872 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-27744541073&partnerID=MN8TOARS ER - TY - JOUR TI - Receiver designs for Alamouti coded OFDM systems in fast fading channels T2 - IEEE Transactions on Wireless Communications AB - In this paper, receiver designs for orthogonal frequency-division multiplexing (OFDM) systems that exploit the Alamouti transmit diversity technique are addressed. In Alamouti space-time coded OFDM systems, the simple Alamouti decoding at the receiver relies on the assumption that the channels do not change over an Alamouti codeword period (two consecutive OFDM symbol periods). Unfortunately, when the channel is fast fading, the assumption is not met, resulting in severe performance degradation. In this paper, a sequential decision feedback sequence estimation (SDFSE) scheme with an adaptive threshold (AT), a traditionally single-carrier equalization technique, is used to mitigate the performance degradation. A new method to set the threshold value is proposed. For small signal constellations like BPSK and QPSK, the SDFSE with an AT requires much lower complexity than a previous minimum mean square error approach at the cost of a small performance degradation. Furthermore, we show that the performance difference becomes smaller when channel estimation error is included. An adaptive effort sequence estimation (AESE) scheme is also proposed to furthur reduce the average complexity of the SDFSE scheme with an AT. The AESE scheme is based on the observation that a high Doppler frequency does not necessarily mean significant instantaneous channel variation. Simulations show the efficacy of the proposed SDFSE with an AT and the AESE. DA - 2005/// PY - 2005/// DO - 10.1109/TWC.2004.843042 VL - 4 IS - 2 SP - 550-559 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-17144375611&partnerID=MN8TOARS KW - equalization KW - fast fading KW - orthogonal frequency-division multiplexing (OFDM) KW - sequence estimation KW - transmit diversity ER - TY - CONF TI - Unequal power allocation for JPEG transmission over MIMO systems C2 - 2005/// C3 - Conference Record - Asilomar Conference on Signals, Systems and Computers DA - 2005/// VL - 2005 SP - 1608-1612 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33847652903&partnerID=MN8TOARS ER - TY - JOUR TI - Space-time interference cancellation in MIMO-OFDM systems T2 - IEEE Transactions on Vehicular Technology AB - In this paper, a two stage hybrid interference cancellation and equalization framework is proposed for interference cancellation in the uplink of multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems. The first stage uses time domain equalization to suppress cochannel interference, mitigate asynchronism, and shorten the postequalization channel response to be no longer than the length of the cyclic prefix. The second stage performs low-complexity single tap equalization and detection in the frequency domain. The framework is developed specifically for spatial multiplexing and is applied to multiuser MIMO-OFDM systems with asynchronism between users as well as to single-user MIMO-OFDM systems. Various equalizer design methods are proposed that determine the coefficients directly from the training data and are compared with methods based on channel estimates. The equalizer coefficients and postequalization channel response are found by solving a joint optimization that maximizes the signal to interference-plus-noise ratio (SINR) in the frequency domain. Simulations compare various training-based methods and show the proposed methods provide good bit error rate (BER) and SINR performance in a variety of interference scenarios. DA - 2005/// PY - 2005/// DO - 10.1109/TVT.2005.851299 VL - 54 IS - 5 SP - 1802-1816 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-29044433176&partnerID=MN8TOARS KW - cancellation KW - interference KW - MIMO KW - OFDM KW - space-time ER - TY - JOUR TI - Space-time chase decoding T2 - IEEE Transactions on Wireless Communications AB - Multiple-antenna wireless systems are of interest because they provide increased capacity over single-antenna systems. Several space-time signaling schemes have been proposed to make use of this increased capacity. Space-time techniques, such as space-time block coding and spatial multiplexing, can all be viewed as signaling with a multidimensional constellation. Because of the large capacity of multiple-input multiple-output (MIMO) channels, these multidimensional constellations often have large cardinalities. For this reason, it is impractical to perform optimal maximum-likelihood (ML) decoding for space-time systems, even for a moderate number of transmit antennas. In this paper, we propose a modified version of the classic Chase decoder for multiple-antenna systems. The decoder applies successive detection to yield an initial estimate of the transmitted bit sequence, constructs a list of candidate symbol vectors using this initial estimate, and then computes bit likelihood information over this list. Three algorithms are presented for constructing the candidate vector list. This decoder can be adjusted to have a fixed or variable complexity, while maintaining performance close to that of an ML decoder. DA - 2005/// PY - 2005/// DO - 10.1109/TWC.2005.853830 VL - 4 IS - 5 SP - 2035-2039 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-28444490067&partnerID=MN8TOARS KW - chase decoding KW - maximum-likelihood (ML) decoding KW - multiple-input multiple-output (MIMO) systems KW - spatial multiplexing KW - sphere decoding ER - TY - CONF TI - Rate bounds for MIMO relay channels using precoding AB - Relay channels plays a central role in next-generation multihop wireless systems. This paper considers the MIMO relay channel where multiple antennas are employed by each terminal. New lower bounds on the capacity of a Gaussian MIMO relay channel are derived under the assumption that the transmitter employs either superposition coding or dirty-paper coding. The proposed lower bounds improve on a previously proposed lower bound that arises from a simple transmit strategy. C2 - 2005/// C3 - GLOBECOM - IEEE Global Telecommunications Conference DA - 2005/// DO - 10.1109/GLOCOM.2005.1577838 VL - 3 SP - 1172-1176 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33846594834&partnerID=MN8TOARS ER - TY - CONF TI - Quantized multi-mode precoding for spatial multiplexing MIMO-OFDM system AU - Khaled, N. AU - Mondal, B. AU - Heath, R.W. AU - Leus, G. AU - Petre, F. AB - Spatial multiplexing with multi-mode precoding can achieve both high capacity and high reliability in multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems. Multimode precoding uses linear transmit precoding but adapts the number of transmit streams or modes according to the channel conditions. Multi-mode precoding typically requires complete knowledge of the transmit precoding matrices for each subcarrier at the transmitter. In this paper we propose to reduce the feedback requirements by sending back the quantized precoding matrices of a fraction of the subcarriers and obtaining the other precoders using interpolation. Two algorithms are proposed for the interpolation of unitary matrices. Bit error rates simulations demonstrate the performance improvements of the proposed algorithms as a function of the feedback rate. C2 - 2005/// C3 - IEEE Vehicular Technology Conference DA - 2005/// DO - 10.1109/VETECF.2005.1558048 VL - 2 SP - 867-871 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84931464076&partnerID=MN8TOARS ER - TY - JOUR TI - Necessary and sufficient conditions for full diversity order in correlated Rayleigh fading beamforming and combining systems T2 - IEEE Transactions on Wireless Communications AB - Transmit beamforming and receive combining are low complexity, linear techniques that make use of the spatial diversity advantage provided by transmitters and/or receivers employing multiple antennas. There has been a growing interest in designing beamforming schemes for frequency division duplexing systems that use a limited amount of feedback from the receiver to the transmitter. This limited feedback conveys a beamforming vector chosen from a finite set known to both the transmitter and receiver. These techniques often use a set of beamforming vectors where the probability of error expression can not be easily formulated or bounded. It is of utmost importance to guarantee that the sets of beamforming and combining vectors are chosen such that full diversity order is achieved. For this reason, necessary and sufficient conditions on the sets of possible beamformers and combiners are derived that guarantee full diversity order in correlated Rayleigh fading. DA - 2005/// PY - 2005/// DO - 10.1109/TWC.2004.840197 VL - 4 IS - 1 SP - 20-23 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-19944392275&partnerID=MN8TOARS KW - beamforming KW - combining KW - correlated fading KW - diversity methods KW - MIMO systems KW - Rayleigh channels KW - transmitreceive diversity ER - TY - JOUR TI - OFDM power loading using limited feedback T2 - IEEE Transactions on Vehicular Technology AB - Orthogonal frequency division multiplexing (OFDM) is a practical broadband signaling technique for use in multipath fading channels. Over the past ten years, research has shown that power loading, where the power allocations on the OFDM frequency tones are jointly optimized, can improve error rate or capacity performance. The implementation of power loading, however, is dependent on the presence of complete forward link channel knowledge at the transmitter. In systems using frequency division duplexing (FDD), this assumption is unrealistic. In this paper, we propose power loading for OFDM symbols using a limited number of feedback bits sent from the receiver to the transmitter. The power loading vector is designed at the receiver, which is assumed to have perfect knowledge of the forward link channel, and conveyed back to the transmitter over a limited rate feedback channel. To allow for the vector to be represented by a small number of bits, the power loading vector is restricted to lie in a finite set, or codebook, of power loading vectors. This codebook is designed offline and known a priori to both the transmitter and receiver. We present two power allocation selection algorithms that optimize the probability of symbol error and capacity, respectively. Simulation results show that the proposed limited feedback techniques provide performance close to full channel knowledge power loading. DA - 2005/// PY - 2005/// DO - 10.1109/TVT.2005.853473 VL - 54 IS - 5 SP - 1773-1780 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-29044437088&partnerID=MN8TOARS KW - limited feedback KW - orthogonal frequency division multiplexing KW - power loading ER - TY - JOUR TI - Multimode precoding for MIMO wireless systems T2 - IEEE Transactions on Signal Processing AB - Multiple-input multiple-output (MIMO) wireless systems obtain large diversity and capacity gains by employing multielement antenna arrays at both the transmitter and receiver. The theoretical performance benefits of MIMO systems, however, are irrelevant unless low error rate, spectrally efficient signaling techniques are found. This paper proposes a new method for designing high data-rate spatial signals with low error rates. The basic idea is to use transmitter channel information to adaptively vary the transmission scheme for a fixed data rate. This adaptation is done by varying the number of substreams and the rate of each substream in a precoded spatial multiplexing system. We show that these substreams can be designed to obtain full diversity and full rate gain using feedback from the receiver to transmitter. We model the feedback using a limited feedback scenario where only finite sets, or codebooks, of possible precoding configurations are known to both the transmitter and receiver. Monte Carlo simulations show substantial performance gains over beamforming and spatial multiplexing. DA - 2005/// PY - 2005/// DO - 10.1109/TSP.2005.855107 VL - 53 IS - 10 I SP - 3674-3687 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-27844521745&partnerID=MN8TOARS KW - diversity methods KW - MIMO systems KW - quantized precoding KW - Rayleigh channels KW - spatial multiplexing ER - TY - JOUR TI - Multimode antenna selection for spatial multiplexing systems with linear receivers T2 - IEEE Transactions on Signal Processing AB - Spatial multiplexing is a simple transmission technique for multiple-input multiple-output (MIMO) wireless communication links in which data is multiplexed across the transmit antennas. In Rayleigh fading matrix channels, however, spatial multiplexing with low-complexity linear receivers suffers due to a lack of diversity advantage. This paper proposes multimode antenna selection, which uses a low-rate feedback channel to improve the error rate performance of spatial multiplexing systems with linear receivers. In the proposed technique, both the number of substreams and the mapping of substreams to antennas are dynamically adjusted, for a fixed total data rate, to the channel based on limited feedback from the receiver. Dual-mode selection, where spatial multiplexing or selection diversity is adaptively chosen, dramatically improves the diversity gain achieved. Multimode selection (i.e., allowing any number of substreams to be dynamically selected) provides additional array gain. Various criteria for selecting the number of substreams and the optimal mapping of substreams to transmit antennas are derived. Relationships are made between the selection criteria and the eigenmodes of the channel. A probabilistic analysis of the selection criteria are provided for Rayleigh fading channels. Applications to nonlinear receivers are mentioned. Monte Carlo simulations demonstrate significant performance improvements in independent and identically distributed (i.i.d.) flat-fading Rayleigh matrix channels with minimal feedback. DA - 2005/// PY - 2005/// DO - 10.1109/TSP.2005.851109 VL - 53 IS - 8 SP - 3042-3056 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-25444488050&partnerID=MN8TOARS KW - antenna selection KW - diversity methods KW - MIMO systems ER - TY - CONF TI - Performance of the MIMO downlink channel with multi-mode adaptation and scheduling AB - This paper presents an algorithm for switching transmission methods (whether for diversity or data rate maximization) over a multiple antenna broadcast channel. The proposed approach exploits long-term spatial selectivity of the user channels to decide between different diversity and multiplexing modes. We investigate the performance of this adaptive transmission method with different scheduling polices (both sensitive to user queue sizes and independent of user queue sizes). While the methods outlined in this paper are general, we present our results in the context of a broadcast channel with four transmit antennas at the central transmitter, and four antennas at each receiver. Our results indicate a gain of approximately 20% in average system throughput with the proposed algorithm over realistic channel models. C2 - 2005/// C3 - IEEE Workshop on Signal Processing Advances in Wireless Communications, SPAWC DA - 2005/// DO - 10.1109/SPAWC.2005.1506229 VL - 2005 SP - 695-699 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33745485346&partnerID=MN8TOARS ER - TY - CONF TI - Performance evaluation of 2-element arrays of circular patch antennas in indoor clustered MIMO channels AB - In this paper we present a computationally efficient method to evaluate the performance of circular patch arrays (CPAs) in clustered MIMO channel models. The proposed method is based on bounds to the eigenvalues of the spatial correlation matrix that are shown to depend only on the channel angle spread. From these bounds, we derive a closed-form expression of the MIMO ergodic capacity as a function of the angle spread, which is used to estimate the performance of CPAs in different propagation environments. This method yields dramatic reduction in computational complexity due to the reduced number of channel parameters required for performance evaluation of CPAs. Simulation results show that through this method it is possible to predict the performance of CPAs, with negligible capacity loss (below 2%), for the most practical channel scenarios C2 - 2005/// C3 - Proceedings - IEEE Military Communications Conference MILCOM DA - 2005/// DO - 10.1109/MILCOM.2005.1605655 VL - 2005 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33847403480&partnerID=MN8TOARS ER - TY - JOUR TI - Opportunistic feedback for downlink multiuser diversity T2 - IEEE Communications Letters AB - This paper proposes a random access based feedback protocol for achieving multiuser diversity with a fixed number of feedback slots. Active users send a feedback message with some probability if their channel power is above a threshold. The threshold and random access probability are jointly designed to maximize the average sum rate of all users. DA - 2005/// PY - 2005/// DO - 10.1109/LCOMM.2005.10002 VL - 9 IS - 10 SP - 948-950 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-27644435489&partnerID=MN8TOARS KW - feedback KW - multiuser channels KW - diversity methods KW - protocols KW - opportunistic ER - TY - CONF TI - Min-SER space-time equalization in asynchronous MIMO-OFDM systems AB - In this paper, we propose an algorithm for the design of space-time equalizer in asynchronous MIMO-OFDM systems. The equalizer is designed to null the co-channel interference and combat asynchronism as well as minimize a lower bound to the symbol error rate. Numerical simulations show good uncoded bit error rate performance for our proposed algorithm. C2 - 2005/// C3 - IEEE Workshop on Signal Processing Advances in Wireless Communications, SPAWC DA - 2005/// DO - 10.1109/SPAWC.2005.1506063 VL - 2005 SP - 440-444 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33745502195&partnerID=MN8TOARS ER - TY - CONF TI - Pattern diversity with multi-mode circular patch antennas in clustered MIMO channels AB - The throughput that a MIMO channel can support is a function of different array parameters. Another technique, for miniaturized antenna designs, is polarization/pattern diversity where the antennas are designed to radiate with orthogonal radiation patterns and polarizations as a means to create uncorrelated channels across different array elements. The benefits of pattern diversity have been shown by L. Dong et al. (2003). That analysis, however, did not use realistic channel models. We aim to extend the analysis of Dong et al. to clustered channel models, adopted by the IEEE 802.11n standard body for wireless local area networks (WLANs). We analyze MIMO arrays consisting of circular microstrip antennas to enable pattern diversity and compare their performance against conventional uniform linear arrays. We also model the effect of mutual coupling and measure the performance degradation produced by the near-field effects. We briefly review the channel model and the properties of circular microstrip antennas. Then, we analytically compute the spatial correlation coefficients and evaluate the MIMO channel capacity. Pattern diversity yields better performance than space diversity. C2 - 2005/// C3 - IEEE Antennas and Propagation Society, AP-S International Symposium (Digest) DA - 2005/// DO - 10.1109/APS.2005.1552537 VL - 3 B SP - 438-441 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33846908339&partnerID=MN8TOARS ER - TY - CONF TI - Multiple description image coding using natural scene statistics AB - The statistics of natural scenes in the wavelet domain are accurately characterized by the Gaussian scale mixture (GSM) model. The model lends itself easily to analysis and many applications that use this model are emerging (e.g., denoising, watermark detection). We present an error-resilient image communications application that uses the GSM model and multiple description coding (MDC) to provide error-resilience. We derive a rate-distortion bound for GSM random variables, derive the redundancy rate-distortion function, and finally implement an MD image communication system. C2 - 2005/// C3 - ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings DA - 2005/// DO - 10.1109/ICASSP.2005.1415398 VL - II UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33646782604&partnerID=MN8TOARS ER - TY - JOUR TI - Limited feedback unitary precoding for orthogonal space-time block codes T2 - IEEE Transactions on Signal Processing AB - Orthogonal space-time block codes (OSTBCs) are a class of easily decoded space-time codes that achieve full diversity order in Rayleigh fading channels. OSTBCs exist only for certain numbers of transmit antennas and do not provide array gain like diversity techniques that exploit transmit channel information. When channel state information is available at the transmitter, though, precoding the space-time codeword can be used to support different numbers of transmit antennas and to improve array gain. Unfortunately, transmitters in many wireless systems have no knowledge about current channel conditions. This motivates limited feedback precoding methods such as channel quantization or antenna subset selection. This paper investigates a limited feedback approach that uses a codebook of precoding matrices known a priori to both the transmitter and receiver. The receiver chooses a matrix from the codebook based on current channel conditions and conveys the optimal codebook matrix to the transmitter over an error-free, zero-delay feedback channel. A criterion for choosing the optimal precoding matrix in the codebook is proposed that relates directly to minimizing the probability of symbol error of the precoded system. Low average distortion codebooks are derived based on the optimal codeword selection criterion. The resulting design is found to relate to the famous applied mathematics problem of subspace packing in the Grassmann manifold. Codebooks designed by this method are proven to provide full diversity order in Rayleigh fading channels. Monte Carlo simulations show that limited feedback precoding performs better than antenna subset selection. DA - 2005/// PY - 2005/// DO - 10.1109/TSP.2004.838928 VL - 53 IS - 1 SP - 64-73 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-11844289606&partnerID=MN8TOARS KW - diversity methods KW - Grassmannian subspace packing KW - MIMO systems KW - orthogonal space-time block coding KW - quantized precoding KW - Rayleigh channels ER - TY - JOUR TI - Limited feedback unitary precoding for spatial multiplexing systems T2 - IEEE Transactions on Information Theory AB - Multiple-input multiple-output (MIMO) wireless systems use antenna arrays at both the transmitter and receiver to provide communication links with substantial diversity and capacity. Spatial multiplexing is a common space-time modulation technique for MIMO communication systems where independent information streams are sent over different transmit antennas. Unfortunately, spatial multiplexing is sensitive to ill-conditioning of the channel matrix. Precoding can improve the resilience of spatial multiplexing at the expense of full channel knowledge at the transmitter-which is often not realistic. This correspondence proposes a quantized precoding system where the optimal precoder is chosen from a finite codebook known to both receiver and transmitter. The index of the optimal precoder is conveyed from the receiver to the transmitter over a low-delay feedback link. Criteria are presented for selecting the optimal precoding matrix based on the error rate and mutual information for different receiver designs. Codebook design criteria are proposed for each selection criterion by minimizing a bound on the average distortion assuming a Rayleigh-fading matrix channel. The design criteria are shown to be equivalent to packing subspaces in the Grassmann manifold using the projection two-norm and Fubini-Study distances. Simulation results show that the proposed system outperforms antenna subset selection and performs close to optimal unitary precoding with a minimal amount of feedback. DA - 2005/// PY - 2005/// DO - 10.1109/TIT.2005.850152 VL - 51 IS - 8 SP - 2967-2976 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-23844475192&partnerID=MN8TOARS KW - diversity methods KW - Grassmannian subspace packing KW - multiple-input multiple-output (MIMO) systems KW - quantized precoding KW - Rayleigh channels KW - spatial multiplexing KW - vertical Bell Labs layered spacetime (V-BLAST) architecture ER - TY - JOUR TI - Interpolation based transmit beamforming for MIMO-OFDM with limited feedback T2 - IEEE Transactions on Signal Processing AB - Transmit beamforming and receive combining are simple methods for exploiting spatial diversity in multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) system. Optimal beamforming requires channel state information in the form of the beamforming vectors for each OFDM subcarrier. This paper proposes a limited feedback architecture that combines beamforming vector quantization and smart vector interpolation. In the proposed system, the receiver sends a fraction of information about the optimal beamforming vectors to the transmitter and the transmitter computes the beamforming vectors for all subcarriers through interpolation. A new spherical interpolator is developed that exploits parameters for phase rotation to satisfy the phase invariance and unit norm properties of the transmitted beamforming vectors. The beamforming vectors and phase parameters are quantized at the receiver and the quantized information is provided to the transmitter. The proposed quantization system provides only a moderate increase in complexity versus over comparable approaches. Numerical simulations show that the proposed scheme performs better than existing diversity techniques with the same feedback data rate. DA - 2005/// PY - 2005/// DO - 10.1109/TSP.2005.857019 VL - 53 IS - 11 SP - 4125-4135 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-27744559310&partnerID=MN8TOARS KW - antenna diversity KW - MIMO-OFDM KW - mutual information KW - spherical interpolation KW - transmit beamforming ER - TY - JOUR TI - Designing structured tight frames via an alternating projection method T2 - IEEE Transactions on Information Theory AB - Tight frames, also known as general Welch-bound- equality sequences, generalize orthonormal systems. Numerous applications - including communications, coding, and sparse approximation- require finite-dimensional tight frames that possess additional structural properties. This paper proposes an alternating projection method that is versatile enough to solve a huge class of inverse eigenvalue problems (IEPs), which includes the frame design problem. To apply this method, one needs only to solve a matrix nearness problem that arises naturally from the design specifications. Therefore, it is the fast and easy to develop versions of the algorithm that target new design problems. Alternating projection will often succeed even if algebraic constructions are unavailable. To demonstrate that alternating projection is an effective tool for frame design, the paper studies some important structural properties in detail. First, it addresses the most basic design problem: constructing tight frames with prescribed vector norms. Then, it discusses equiangular tight frames, which are natural dictionaries for sparse approximation. Finally, it examines tight frames whose individual vectors have low peak-to-average-power ratio (PAR), which is a valuable property for code-division multiple-access (CDMA) applications. Numerical experiments show that the proposed algorithm succeeds in each of these three cases. The appendices investigate the convergence properties of the algorithm. DA - 2005/// PY - 2005/// DO - 10.1109/TIT.2004.839492 VL - 51 IS - 1 SP - 188-209 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-12444320397&partnerID=MN8TOARS KW - algorithms KW - code-division multiple access (CDMA) KW - eigenvalues and eigenfunctions KW - extremal problems KW - frames KW - geometry KW - inverse problems KW - sequences ER - TY - CONF TI - Interpolation-based multi-mode precoding for MIMO-OFDM systems C2 - 2005/// C3 - 13th European Signal Processing Conference, EUSIPCO 2005 DA - 2005/// SP - 1552-1555 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84863701197&partnerID=MN8TOARS ER - TY - CONF TI - Frame theoretic quantization for limited feedback MIMO beamforming systems AB - In an uncorrelated Rayleigh fading channel, multiple-input multiple-output (MIMO) beamforming-combining systems can attain full diversity and significant array gain using channel knowledge at the transmitter. In the absence of channel knowledge at the transmitter, a beamforming vector can be quantized at the receiver using a fixed pre-determined codebook of beamforming vectors and the codeword index can be sent to the transmitter. Designing optimal codebooks (that maximize expected SNR) is an open problem and vector quantization (VQ) and Grassmannian line packings (GLP) have been proposed as possible solutions. In this paper, a mutual information based codebook design criterion is introduced and equiangular frames (EF) are proposed as beamforming codebooks satisfying this criterion. Besides providing a systematic way to design codebooks, EFs result in higher receive signal-to-noise ratio compared to codebooks designed using VQ or GLP. C2 - 2005/// C3 - 2005 International Conference on Wireless Networks, Communications and Mobile Computing DA - 2005/// DO - 10.1109/WIRLES.2005.1549560 VL - 2 SP - 1065-1070 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-34547236839&partnerID=MN8TOARS ER - TY - CONF TI - Capacity enhancement via multi-mode adaptation in spatially correlated MIMO channels C2 - 2005/// C3 - IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC DA - 2005/// VL - 2 SP - 754-758 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-34047199879&partnerID=MN8TOARS ER - TY - CONF TI - Low complexity user selection algorithms for multiuser MIMO systems with block diagonalization C2 - 2005/// C3 - Conference Record - Asilomar Conference on Signals, Systems and Computers DA - 2005/// VL - 2005 SP - 628-632 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33847644173&partnerID=MN8TOARS ER - TY - CONF TI - Frame based multiple description image coding in the wavelet domain AB - Multiple description codes generated by quantized frame expansions have been shown to perform well on erasure channels when compared to traditional channel codes. In this paper we propose a multiple description image coding scheme in the wavelet domain using quantized frame expansions. We form zerotrees from wavelet coefficients and apply a tight frame operator to the zerotrees. We then group appropriate expansions to form packets and evaluate the performance of the scheme over an erasure channel. We compare the performance of the proposed scheme with a conventional channel coding scheme. C2 - 2005/// C3 - Proceedings - International Conference on Image Processing, ICIP DA - 2005/// DO - 10.1109/ICIP.2005.1530543 VL - 3 SP - 920-923 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33749236975&partnerID=MN8TOARS ER - TY - CONF TI - Codebook adaptation for quantized MIMO beamforming systems C2 - 2005/// C3 - Conference Record - Asilomar Conference on Signals, Systems and Computers DA - 2005/// VL - 2005 SP - 376-380 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33847689465&partnerID=MN8TOARS ER - TY - CONF TI - Adaptive MIMO transmission scheme: Exploiting the spatial selectivity of wireless channels C2 - 2005/// C3 - IEEE Vehicular Technology Conference DA - 2005/// VL - 61 SP - 3188-3192 M1 - 5 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-26444553593&partnerID=MN8TOARS ER - TY - CONF TI - Antenna partitioning for multiuser MIMO-CDMA AB - Improving downlink CDMA capacity has been an area of intensive research for the past decade, especially as the downlink has become the capacity limiting link. Multi-antenna technologies are an obvious candidate for increasing the downlink capacity, but successfully decoding spatially multiplexed signals is very challenging in an interference-limited environment, such as that of CDMA cellular systems. In this paper, a simple and novel MIMO-CDMA system design is developed, in which users are assigned to a transmit antenna either without regard to channel knowledge (static) or based on antenna selection feedback bits (dynamic). These proposed antenna partitioning techniques have a minimal increase in complexity and require only small changes to existing CDMA standards. The outage probability and capacity of the proposed systems are derived and it is shown that they outperform conventional CDMA systems regardless of the number of antennas or antenna partitioning technique. C2 - 2005/// C3 - GLOBECOM - IEEE Global Telecommunications Conference DA - 2005/// DO - 10.1109/GLOCOM.2005.1577908 VL - 3 SP - 1535-1539 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33846576637&partnerID=MN8TOARS ER - TY - CONF TI - Algorithms for quantized precoded MIMO-OFDM systems C2 - 2005/// C3 - Conference Record - Asilomar Conference on Signals, Systems and Computers DA - 2005/// VL - 2005 SP - 381-385 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33847639400&partnerID=MN8TOARS ER - TY - CONF TI - A space-time receiver for MIMO-OFDM ad hoc networks AB - In this paper, we propose a receiver architecture that can demodulate multiple data streams with different frequency offsets and propagation delays in multiple input multiple output orthogonal frequency division multiplexing (MIMO-OFDM) ad hoc networks. The receiver performs joint synchronization and interference cancellation to separate these interfering data streams and achieve synchronization for each stream. We propose a novel training-based minimizing mean square error (MMSE) algorithm to jointly obtain the frequency offsets and the equalization delays. The effects of frequency offsets and propagation delays are compensated with these estimated parameters. We also propose a direct training-based equalizer design algorithm to obtain the equalizer coefficients. This algorithm involves solving an optimization problem that considers symbol error rate. Simulation shows good uncoded bit error rate performance for our proposed algorithms. C2 - 2005/// C3 - Proceedings - IEEE Military Communications Conference MILCOM DA - 2005/// DO - 10.1109/MILCOM.2005.1605874 VL - 2005 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33847363093&partnerID=MN8TOARS ER - TY - CONF TI - Algorithms for quantized precoding in MIMO OFDM beamforming systems AB - Multiple input multiple output (MIMO) wireless systems can offer significant diversity and transmit beamforming with receive combining provides a method to achieve this diversity with simple receive processing. The maximum gains in terms of array gain and diversity, however, requires perfect channel knowledge at the transmitter. In the absence of perfect channel knowledge, the channel information can be quantized at the receiver and sent back to the transmitter using a low-rate feedback link. In the case of narrowband channels, considerable work has been done in reducing the feedback information while maintaining bit-error-rate performance close to the case of perfect channel knowledge. This work, however, does not naturally extend to the case of frequency selective channels and leads to an explosion in the feedback overhead. In this paper, orthogonal frequency division multiplexing (OFDM)is considered as a low complexity implementation of MIMO beamforming combining over frequency selective channels. Two broad classes of algorithms are discussed for quantizing channel information - clustering and transform. The clustering algorithms group the subcarriers and choose a common frequency-domain representation of the channel information for each group. Thus the feedback rate depends on the number of groups and not on the number of subcarriers. The transform algorithms quantize the channel information in time-domain where the transform essentially decorrelates the channel information. Both the algorithms provide significant compression of channel information maintaining bit-error-rate performance close to the case of perfect channel knowledge. C2 - 2005/// C3 - Proceedings of SPIE - The International Society for Optical Engineering DA - 2005/// DO - 10.1117/12.612595 VL - 5847 SP - 80-87 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-28444496353&partnerID=MN8TOARS KW - MIMO OFDM KW - beamforming KW - quantization KW - clustering KW - feedback ER - TY - CONF TI - A joint MIMO-OFDM transceiver and MAC design for mobile ad hoc networking C2 - 2005/// C3 - 2004 International Workshop on Wireless Ad-Hoc Networks DA - 2005/// SP - 315-319 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-28244475399&partnerID=MN8TOARS ER - TY - JOUR TI - Synthesis and Film-Forming Properties of Ethynylporphyrins AU - Liu, Zhiming AU - Schmidt, Izabela AU - Thamyongkit, Patchanita AU - Loewe, Robert S. AU - Syomin, Dennis AU - Diers, James R. AU - Zhao, Qian AU - Misra, Veena AU - Lindsey, Jonathan S. AU - Bocian, David F. T2 - Chemistry of Materials AB - Thermal treatment of ethynyl porphyrin monomers on a surface has been found to yield robust porphyrin films. The scope of this in situ polymerization has been surveyed by the synthesis and characterization of a collection of 20 zinc porphyrins bearing diverse patterns of 1−4 ethyne (or protected ethyne) groups and a variety of nonlinking substituents. Films have been prepared on Si(100), SiO2, Au(111), and glass. The films prepared on Si(100) have been examined by electrochemical methods, which indicate that surface coverages 50-fold greater than those of saturation-coverage monolayers are achievable, although the coverage varies appreciably (10-fold) among the survey group of molecules under a controlled set of film-forming conditions. Variation in these conditions affords control over the number of layers in the film (from a few to tens or more). The electrochemical characteristics of the multilayer films further indicate that the redox thermodynamics are of comparable homogeneity to those of monolayers. Examination of the films by FTIR and resonance Raman spectroscopy indicates the absence of an ethynyl or ethenyl linkage between the porphyrins. SEM analysis indicates the porphyrin polymer films range in thickness from tens to hundreds of nanometers. The in situ polymerization technique not only enables control over the thickness of the porphyrin polymer film but also sidesteps solubility problems that typically result upon solution polymerization. The ability to access the porphyrins in the films electrochemically to form porphyrin cation radicals affords increased surface charge density versus that with a monolayer, suggesting the application of the porphyrin films as materials for electrically addressable, molecular-based information storage. DA - 2005/7// PY - 2005/7// DO - 10.1021/cm047858y VL - 17 IS - 14 SP - 3728-3742 J2 - Chem. Mater. LA - en OP - SN - 0897-4756 1520-5002 UR - http://dx.doi.org/10.1021/cm047858y DB - Crossref ER - TY - JOUR TI - Cover Picture: An Engineered Virus as a Scaffold for Three-Dimensional Self-Assembly on the Nanoscale (Small 7/2005) AU - Blum, Amy Szuchmacher AU - Soto, Carissa M. AU - Wilson, Charmaine D. AU - Brower, Tina L. AU - Pollack, Steven K. AU - Schull, Terence L. AU - Chatterji, Anju AU - Lin, Tianwei AU - Johnson, John E. AU - Amsinck, Christian AU - Franzon, Paul AU - Shashidhar, Ranganathan AU - Ratna, Banahalli R. T2 - Small DA - 2005/7// PY - 2005/7// DO - 10.1002/smll.200590023 VL - 1 IS - 7 SP - 669-669 J2 - Small LA - en OP - SN - 1613-6810 1613-6829 UR - http://dx.doi.org/10.1002/smll.200590023 DB - Crossref ER - TY - JOUR TI - Cover Picture: An Engineered Virus as a Scaffold for Three-Dimensional Self-Assembly on the Nanoscale (Small 7/2005) AU - Blum, Amy Szuchmacher AU - Soto, Carissa M. AU - Wilson, Charmaine D. AU - Brower, Tina L. AU - Pollack, Steven K. AU - Schull, Terence L. AU - Chatterji, Anju AU - Lin, Tianwei AU - Johnson, John E. AU - Amsinck, Christian AU - Franzon, Paul AU - Shashidhar, Ranganathan AU - Ratna, Banahalli R. T2 - Small DA - 2005/7// PY - 2005/7// DO - 10.1002/smll.200590022 VL - 1 IS - 7 SP - 669-669 J2 - Small LA - en OP - SN - 1613-6810 1613-6829 UR - http://dx.doi.org/10.1002/smll.200590023 DB - Crossref ER - TY - JOUR TI - A study of bacterial flagellar bundling AU - Flores, H AU - Lobaton, E AU - Mendezdiez, S AU - Tlupova, S AU - Cortez, R T2 - Bulletin of Mathematical Biology DA - 2005/1// PY - 2005/1// DO - 10.1016/J.BULM.2004.06.006 VL - 67 IS - 1 SP - 137-168 J2 - Bulletin of Mathematical Biology LA - en OP - SN - 0092-8240 UR - http://dx.doi.org/10.1016/J.BULM.2004.06.006 DB - Crossref ER - TY - JOUR TI - Emission properties of a-plane GaN grown by metal-organic chemical-vapor deposition AU - Paskov, P. P. AU - Schifano, R. AU - Monemar, B. AU - Paskova, T. AU - Figge, S. AU - Hommel, D. T2 - Journal of Applied Physics AB - We report on the emission properties of nonpolar a-plane GaN layers grown on r-plane sapphire. Temperature-, excitation-density-, and polarization-dependent photoluminescences and spatially resolved microphotoluminescence and cathodoluminescence are employed in order to clarify the nature of the different emission bands in the 3.0–3.5eV spectral range. In the near band-edge region the emission lines of the donor-bound excitons (3.472eV) and free excitons (3.478eV) are resolved in the polarized low-temperature spectra, indicating a good quality of the layers. At low energies two other emissions bands with intensity and shape varying with the excited area are observed. The 3.42eV emission commonly attributed to the excitons bound to basal plane stacking faults shows thermal quenching with two activation energies (7 and 30meV) and an S-shaped temperature dependence of the peak position. This behavior is analyzed in terms of hole localization in the vicinity of the stacking faults. The emission band that peaked at 3.29eV is found to blueshift and saturate with increasing excitation intensity. The spatially resolved cathodoluminesence measurements show that the emission is asymmetrically distributed around the triangular-shaped pits occurring at the surface. The 3.29eV emission is suggested to involve impurities, which decorate the partial dislocation terminating the basal stacking faults. DA - 2005/11// PY - 2005/11// DO - 10.1063/1.2128496 VL - 98 IS - 9 SP - 093519 J2 - Journal of Applied Physics LA - en OP - SN - 0021-8979 1089-7550 UR - http://dx.doi.org/10.1063/1.2128496 DB - Crossref ER - TY - JOUR TI - Donor-acceptor pair emission enhancement in mass-transport-grown GaN AU - Paskova, T. AU - Arnaudov, B. AU - Paskov, P. P. AU - Goldys, E. M. AU - Hautakangas, S. AU - Saarinen, K. AU - Södervall, U. AU - Monemar, B. T2 - Journal of Applied Physics AB - A dominating donor-acceptor pair (DAP) emission at about 3.27eV is observed in the photoluminescence and cathodoluminescence spectra of intentionally undoped mass-transport (MT)-grown GaN, while only a weak presence of the DAP emission is recorded in the as-grown hydride vapor phase epitaxial GaN. A comparative study of impurity and native defect incorporation in the as-grown and MT GaN was performed, showing a significant increase of oxygen and empty clusters involving Ga vacancy and oxygen in the MT GaN. Based on the observed results as well as on doping analysis of the structure and kinetic analysis of the emission intensities, we propose an acceptorlike complex, creating a state as a semiclassical potential well near the valence-band top due to the local tensile strain caused by the empty clusters to be responsible for the dominating behavior of the DAP emission. DA - 2005/8// PY - 2005/8// DO - 10.1063/1.1994943 VL - 98 IS - 3 SP - 033508 J2 - Journal of Applied Physics LA - en OP - SN - 0021-8979 1089-7550 UR - http://dx.doi.org/10.1063/1.1994943 DB - Crossref ER - TY - JOUR TI - Structural characteristics and lattice parameters of hydride vapor phase epitaxial GaN free-standing quasisubstrates AU - Darakchieva, V. AU - Paskova, T. AU - Paskov, P. P. AU - Monemar, B. AU - Ashkenov, N. AU - Schubert, M. T2 - Journal of Applied Physics AB - We have studied the lattice parameters of hydride vapor phase epitaxy (HVPE)-GaN quasisubstrates in relation to their structural properties. Layers grown on single-layer metalorganic vapor phase epitaxy (MOVPE) templates and on epitaxial lateral overgrown MOVPE templates are characterized by Raman scattering, high-resolution x-ray diffraction, and reciprocal space mapping. The strain relaxation in the films versus their thickness was found to proceed similarly in the GaN samples grown using the two types of templates but the strain saturates at different nonzero levels. The lattice parameters of relatively thin HVPE-GaN free-standing quasisubstrates indicate that no total strain relaxation is achieved after the sapphire removal. The lattice parameters of the thick quasisubstrates grown on different templates are not affected by the separation process and are found to have values very close to the reference strain-free lattice parameters of GaN powder. DA - 2005/1// PY - 2005/1// DO - 10.1063/1.1823024 VL - 97 IS - 1 SP - 013517 J2 - Journal of Applied Physics LA - en OP - SN - 0021-8979 1089-7550 UR - http://dx.doi.org/10.1063/1.1823024 DB - Crossref ER - TY - JOUR TI - Properties of nonpolar a-plane GaN films grown by HVPE with AlN buffers AU - Paskova, T. AU - Darakchieva, V. AU - Paskov, P.P. AU - Birch, J. AU - Valcheva, E. AU - Persson, P.O.A. AU - Arnaudov, B. AU - Tungasmitta, S. AU - Monemar, B. T2 - Journal of Crystal Growth AB - The influence of high temperature AlN buffer layers on the morphology, structural and optical characteristics of a-plane GaN grown by hydride vapour phase epitaxy on r-plane sapphire was investigated. While the morphology of the a-GaN was found to be significantly improved by using a-plane AlN buffer layer similarly to the effect observed in c-plane hydride vapour phase epitaxy GaN growth, the microstructure ensemble was revealed to be more complicated in comparison to that of the c-plane GaN. Higher dislocation density and prismatic stacking faults were observed. Moreover, in-plane anisotropic structural characteristics were revealed by high resolution X-ray diffraction employing azimuthal dependent and edge X-ray measurement symmetric geometry. In addition, the near band edge photoluminescence peaks, red-shifted with respect to that in c-plane GaN were observed. The latter were explained by the influence of the higher defect density and more complex strain distribution. DA - 2005/7// PY - 2005/7// DO - 10.1016/j.jcrysgro.2005.03.013 VL - 281 IS - 1 SP - 55-61 J2 - Journal of Crystal Growth LA - en OP - SN - 0022-0248 UR - http://dx.doi.org/10.1016/j.jcrysgro.2005.03.013 DB - Crossref KW - GaN KW - a-plane KW - AlN buffer KW - morphology KW - microstructure KW - strain KW - PL KW - HRXRD ER - TY - JOUR TI - Optoelectronic devices on bulk GaN AU - Figge, S. AU - Böttcher, T. AU - Dennemarck, J. AU - Kröger, R. AU - Paskova, T. AU - Monemar, B. AU - Hommel, D. T2 - Journal of Crystal Growth AB - The homoeptaxial fabrication of GaN-based devices has advantages against heteroepitaxial realization on substrates such as sapphire or SiC, since heteroepitaxy implies a lot of problems like lattice mismatch, different thermal expansion coefficients, and needs an extensive optimization of the growth at the heterointerface. In this paper we will discuss GaN-based light-emitting devices grown by homoepitaxy in comparison to devices grown on sapphire. A special emphasis is laid on the pretreatment of the GaN substrate and the device characteristics on different substrates. In detail will be discussed the advantages of the higher thermal conductivity of GaN and how this effects the device performance. DA - 2005/7// PY - 2005/7// DO - 10.1016/j.jcrysgro.2005.03.017 VL - 281 IS - 1 SP - 101-106 J2 - Journal of Crystal Growth LA - en OP - SN - 0022-0248 UR - http://dx.doi.org/10.1016/j.jcrysgro.2005.03.017 DB - Crossref KW - hydride vapor phase epitaxy KW - metalorganic vapor phase epitaxy KW - nitrides ER - TY - JOUR TI - Nonpolara-plane HVPE GaN: growth and in-plane anisotropic properties AU - Paskova, T. AU - Darakchieva, V. AU - Paskov, P. P. AU - Birch, J. AU - Valcheva, E. AU - Persson, P. O. �. AU - Arnaudov, B. AU - Tungasmita, S. AU - Monemar, B. T2 - physica status solidi (c) AB - Nonpolar GaN thick films with [11-20] orientation were grown on [1-102] oriented sapphire by hydride vapour phase epitaxy (HVPE) utilizing reactively sputtered AlN buffers. Growth rate and microstructure of such films were investigated and compared to those in HVPE [0001] oriented GaN thick films. The structural parameters show an angular azimuth dependence implying in-plane non-homogeneity. The lattice parameters and strain components were determined by using plane and edge symmetric measurement geometries. A red shift observed in the near band edge photoluminescence is explained by the specific strain distribution studied independently by X-ray diffraction. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) DA - 2005/5// PY - 2005/5// DO - 10.1002/pssc.200461481 VL - 2 IS - 7 SP - 2027-2031 J2 - phys. stat. sol. (c) LA - en OP - SN - 1610-1634 1610-1642 UR - http://dx.doi.org/10.1002/pssc.200461481 DB - Crossref ER - TY - JOUR TI - Photoluminescence of GaN/AlN superlattices grown by MOCVD AU - Paskov, P. P. AU - Bergman, J. P. AU - Darakchieva, V. AU - Paskova, T. AU - Monemar, B. AU - Iwaya, M. AU - Kamiyama, S. AU - Amano, H. AU - Akasaki, I. T2 - physica status solidi (c) AB - We report on the emission properties of GaN/AlN superlattice (SL) structures grown by MOCVD. A set of samples with AlN thickness below 3 nm and different well/barrier thickness ratios has been studied. The SLs with a period between 3 and 8 nm show a photoluminescence (PL) peak in the range 3.3–3.9 eV with a full width at half maximum of about 100 meV. The difference in the transition energies, linewidths and recombination dynamics is described in terms of varying polarization field and electron filling in the wells. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) DA - 2005/5// PY - 2005/5// DO - 10.1002/pssc.200461367 VL - 2 IS - 7 SP - 2345-2348 J2 - phys. stat. sol. (c) LA - en OP - SN - 1610-1634 1610-1642 UR - http://dx.doi.org/10.1002/pssc.200461367 DB - Crossref ER - TY - JOUR TI - An efficient illumination system for liquid crystal displays incorporating an anisotropic hologram AU - Sánchez, C. AU - Escuti, M. J. AU - van Heesch, C. AU - Bastiaansen, C. W. M. AU - Broer, D. J. T2 - Applied Physics Letters AB - An anisotropic hologram is combined with an edge-lit planar waveguide to produce an improved liquid crystal display (LCD) backlight. A holographic-polymer dispersed liquid crystal material is exposed to a slanted one-dimensional interference pattern to produce an anisotropic Bragg transmission grating with strong diffraction for P-polarized light and very low diffraction for S-polarized light. While the hologram is recorded at a UV wavelength (351 nm), light at visible wavelengths propagating from the waveguide edge is redirected toward the normal direction. The emission is collimated, polarized, and unidirectional, effectively integrating several functions that are typically embodied in separate optical films in a conventional LCD. DA - 2005/8/29/ PY - 2005/8/29/ DO - 10.1063/1.2031942 VL - 87 IS - 9 SP - 094101 J2 - Appl. Phys. Lett. LA - en OP - SN - 0003-6951 1077-3118 UR - http://dx.doi.org/10.1063/1.2031942 DB - Crossref ER - TY - JOUR TI - Photoembossing of Periodic Relief Structures Using Polymerization- Induced Diffusion: A Combinatorial Study AU - Sánchez, C. AU - de Gans, B.-J. AU - Kozodaev, D. AU - Alexeev, A. AU - Escuti, M. J. AU - van Heesch, C. AU - Bel, T. AU - Schubert, U. S. AU - Bastiaansen, C. W. M. AU - Broer, D. J. T2 - Advanced Materials AB - Photoembossing is a solvent-free photolithographic technique for the production of polymeric relief microstructures (see Figure). A combinatorial methodology to explore the influence of different parameters (e.g., processing temperature, binder content, photoinitiator content) on the resultant relief structure is presented using an acrylate-based model system. Results are discussed in the framework of a diffusion-polymerization model. DA - 2005/11/4/ PY - 2005/11/4/ DO - 10.1002/adma.200500777 VL - 17 IS - 21 SP - 2567-2571 J2 - Adv. Mater. LA - en OP - SN - 0935-9648 1521-4095 UR - http://dx.doi.org/10.1002/adma.200500777 DB - Crossref ER - TY - JOUR TI - Cover Picture: TiO2 Nanoparticle-Photopolymer Composites for Volume Holographic Recording (Adv. Funct. Mater. 10/2005) AU - Sánchez, C. AU - Escuti, M. J. AU - van Heesch, C. AU - Bastiaansen, C. W. M. AU - Broer, D. J. AU - Loos, J. AU - Nussbaumer, R. T2 - Advanced Functional Materials AB - Abstract TiO2 nanoparticle–photopolymer composites have been employed for volume holographic recording, as reported by Sánchez and co‐workers on p. 1623. Photoinduced segregation of the high refractive index, grafted nanoparticles between polymer‐rich areas leads to improved refractive‐index modulation amplitudes with respect to the base material without nanoparticles. The cover schematically shows a holographic grating registered in this nanocomposite material. These nanocomposite materials should enable the production of holographic optical elements to efficiently control light with angle and wavelength selectivity. This could be used, for example, in liquid‐crystal display technology. A new and efficient photopolymer for the recording of volume holograms is presented. The material comprises a mixture of UV‐sensitive acrylates and grafted titanium dioxide nanoparticles with an average size of 4 nm. We report the formation of holographic gratings with refractive‐index modulation amplitudes of up to 15.5 × 10 –3 —an improvement of more than a factor of four over the base material without nanoparticles—while maintaining a low level of scattering and a high transparency in the visible‐wavelength range. The influence of the composition of the acrylate system on the final properties of the holographic material is also investigated and discussed. The presence of multifunctional monomers favors the compositional segregation of the different components, while the addition of monofunctional acrylate, highly compatible with the grafting of the nanoparticles, favors the dilution of these nanoparticles. DA - 2005/10// PY - 2005/10// DO - 10.1002/adfm.200590034 VL - 15 IS - 10 SP - NA-NA J2 - Adv. Funct. Mater. LA - en OP - SN - 1616-301X 1616-3028 UR - http://dx.doi.org/10.1002/adfm.200590034 DB - Crossref ER - TY - JOUR TI - TiO2 Nanoparticle-Photopolymer Composites for Volume Holographic Recording AU - Sánchez, C. AU - Escuti, M. J. AU - van Heesch, C. AU - Bastiaansen, C. W. M. AU - Broer, D. J. AU - Loos, J. AU - Nussbaumer, R. T2 - Advanced Functional Materials AB - Abstract A new and efficient photopolymer for the recording of volume holograms is presented. The material comprises a mixture of UV‐sensitive acrylates and grafted titanium dioxide nanoparticles with an average size of 4 nm. We report the formation of holographic gratings with refractive‐index modulation amplitudes of up to 15.5 × 10 –3 —an improvement of more than a factor of four over the base material without nanoparticles—while maintaining a low level of scattering and a high transparency in the visible‐wavelength range. The influence of the composition of the acrylate system on the final properties of the holographic material is also investigated and discussed. The presence of multifunctional monomers favors the compositional segregation of the different components, while the addition of monofunctional acrylate, highly compatible with the grafting of the nanoparticles, favors the dilution of these nanoparticles. DA - 2005/10// PY - 2005/10// DO - 10.1002/adfm.200500095 VL - 15 IS - 10 SP - 1623-1629 J2 - Adv. Funct. Mater. LA - en OP - SN - 1616-301X 1616-3028 UR - http://dx.doi.org/10.1002/adfm.200500095 DB - Crossref ER - TY - JOUR TI - Magnetic properties of Mn-doped GaN andp-i-n junctions AU - Reed, M.L. AU - Reed, M.J. AU - Luen, M.O. AU - Berkman, E.A. AU - Arkun, F.E. AU - Bedair, S.M. AU - Zavada, J.M. AU - El-Masry, N. A. T2 - physica status solidi (c) AB - We report on the growth and magnetic properties of GaMnN films and p-i-n junctions grown by metal-organic chemical vapor deposition. The magnetic properties of MOCVD grown GaMnN were found to depend upon the type and concentration of the co-dopant. Si or Mg co-doping of GaMnN films led to either ferromagnetic or paramagnetic behavior depending on the concentration. The magnetic properties within the GaMnN material system appear to correlate with the position of the Fermi level. Ferromagnetism was observed only when the Fermi energy level was within or very close to the Mn energy band. The presence of the Fermi energy level within the Mn energy band allows the presence of carriers that mediate ferromagnetism. These results further confirm that the ferromagnetic properties result from a solid solution of Mn in the GaN. Mn-doped GaN p-i-n junctions which were grown to study the effect of the magnetic properties on the I/V characteristics. These devices consist of GaN:Si/GaMnN/GaN:Mg layers grown by metal-organic chemical vapor deposition. The carrier concentrations for the n and p-type layers are ∼5 × 1018/cm3 and 1 × 1018/cm3 respectively, where the GaMnN i layer is approximately 0.2–0.45 µm thick with up to 0.5% Mn. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) DA - 2005/5// PY - 2005/5// DO - 10.1002/pssc.200461517 VL - 2 IS - 7 SP - 2403-2406 J2 - phys. stat. sol. (c) LA - en OP - SN - 1610-1634 1610-1642 UR - http://dx.doi.org/10.1002/pssc.200461517 DB - Crossref ER - TY - CHAP TI - Network Access Control for Mobile Ad-Hoc Networks AU - Wang, Pan AU - Ning, Peng AU - Reeves, Douglas S. T2 - Information and Communications Security AB - In this paper, we propose to enforce network access control in Mobile Ad Hoc Networks (MANETs) using cryptographic techniques. In the proposed approach, packets are authenticated by means of a network-wide symmetric (session) key. Because nodes are mobile and communication paths may change rapidly, timely distribution of new session keys is challenging (particularly if keys change frequently). Nodes wishing to communicate may therefore hold different session keys, which must somehow be synchronized. We present a fully distributed key synchronization method based on stateless group key distribution, and localized packet retransmission. If nodes A and B wish to communicate securely over a path P, all nodes on this path must synchronize keys with their immediately adjacent neighbors in the path. Any node which is unable to synchronize keys will not be allowed to forward packets. Simulations and a functioning prototype demonstrate the proposed system is practical and effective. PY - 2005/// DO - 10.1007/11602897_30 SP - 350-362 OP - PB - Springer Berlin Heidelberg SN - 9783540309345 9783540320999 UR - http://dx.doi.org/10.1007/11602897_30 DB - Crossref ER - TY - CONF TI - Series connected IGCT based high power three-level neutral point clamped voltage source inverter pole for FACTS applications AU - Bhattacharya, S. AB - This paper reports requirements, issues and design considerations for high power three-level neutral point clamped (NPC) inverter pole. Dynamic voltage sharing issues, viability and advantages of series connected 4.5 kV, 4 kA IGCT for high power 12 MVA three-level NPC inverter pole are investigated. IGCT turn-off tests at high DC voltage and rated current are used for snubber design and inverter pole clamp design, and to verify simulation results. Experimental results are presented for a two 12 MVA three-level NPC inverter poles operated as H-bridge with three series connected 4.5 kV, 4 kA IGCT per switch C2 - 2005/// C3 - PESC Record - IEEE Annual Power Electronics Specialists Conference DA - 2005/// DO - 10.1109/PESC.2005.1581955 VL - 2005 SP - 2315-2321 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33847744335&partnerID=MN8TOARS ER - TY - CONF TI - Variable frequency variable duty cycle operation of the Controlled Capacitor Charging (CCC) type inverter AU - Chakraborty, C. AU - Dalapati, S. AU - Bhattacharya, S. AB - The controlled capacitor charging (CCC) type inverter uses a simple L-C network, where the capacitor (C) that is connected across the load is charged through an inductor (L) connected in series with the load. The charging in such an inverter has to take place in a controlled manner to produce a desired sinusoidal waveform at the output. This paper presents a variable frequency variable duty cycle based charging technique to keep the output voltage within a hysteresis band, while achieving zero-current switching for every pulse at turn-on. The output voltage across the capacitor and the current through the inductor are fed back to the control circuit. An appropriate logic in the controller determines the width of each individual pulse, as well as the frequency of pulses. Extensive simulations in PSPICE have been carried out. A prototype inverter has been fabricated in the laboratory. Excellent correlation between the simulation and experimental results validated the proposed control technique C2 - 2005/// C3 - IECON Proceedings (Industrial Electronics Conference) DA - 2005/// DO - 10.1109/IECON.2005.1568972 VL - 2005 SP - 598-603 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33749681559&partnerID=MN8TOARS ER - TY - CONF TI - Power flow control on 345 kV lines with the 200 MVA convertible static compensator AU - Shperling, B. AU - Sun, J. AU - Bhattacharya, S. AB - A 200 MVA, 345 kV system control FACTS device, consisting of two 100 MVA converters, two 100 MVA high voltage series transformers inserted in 345 kV transmission lines and a 200 MVA shunt transformer, was tested and utilized on a 345 kV network. This device, namely convertible static compensator (CSC), has four basic configurations: static synchronous compensator (STATCOM), static synchronous series compensator (SSSC), unified power flow controller (UPFC), and interline power flow controller (IPFC). The testing confirmed the device capability to operate in multiple configurations and its ability to control and regulate the power flows on two 345 kV transmission lines. The CSC test results confirmed its capability to regulate the substation bus voltage and line power flows under steady-state and dynamic conditions. The CSC flexibility allows to utilize it during normal as well as various emergency system conditions. C2 - 2005/// C3 - 2005 IEEE Russia Power Tech, PowerTech DA - 2005/// DO - 10.1109/PTC.2005.4524832 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-51549116892&partnerID=MN8TOARS ER - TY - CONF TI - Investigation of high temperature operation of the emitter turn-off thyristor AU - Tewari, K. AU - Chen, B. AU - Li, D. AU - Huang, A.Q. AU - Bhattacharya, S. AB - This paper investigates the emitter turn-off thyristor's (ETO's) high temperature operation from thermal stability point of view. The objective is to identify the electrical and thermal limitations to the high temperature application of the ETO. The loss characteristics of the ETO, including switching loss, conduction loss, and leakage loss are studied experimentally and analytically, at high junction temperature. A closed loop thermal system and stability criterion is developed and analyzed. At low junction temperature, the switching loss determines the thermal stability. At high junction temperature, the high leakage loss leads to thermal instability. From the developed thermal system, the maximum operating junction temperature for the ETO has been derived, under certain operating conditions. Steady state operating junction temperature of 160 Degrees Celsius is obtained for the ETO. C2 - 2005/// C3 - IECON Proceedings (Industrial Electronics Conference) DA - 2005/// DO - 10.1109/IECON.2005.1568978 VL - 2005 SP - 633-638 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33749673997&partnerID=MN8TOARS ER - TY - JOUR TI - Characteristics of low-temperature-grown GaN films on Si(111) AU - Hassan, Z. AU - Lee, Y.C. AU - Yam, F.K. AU - Ibrahim, K. AU - Kordesch, M.E. AU - Halverson, W. AU - Colter, P.C. T2 - Solid State Communications AB - In this paper, we report on the characteristics of GaN films grown on Si(111) at a low temperature (200 °C) by electron cyclotron resonance (ECR) plasma-assisted metalorganic chemical vapor deposition (PA-MOCVD). Structural analysis of the GaN films was performed by using scanning electron microscopy (SEM), atomic force miscroscopy (AFM), X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX), and Rutherford backscattering spectrometry (RBS). Post deposition analysis revealed high quality crystalline GaN was obtained at this low temperature. Electrical analysis of the GaN films was done by using current–voltage (I–V) measurements where electrical characterizations were carried on GaN/Si heterojunction and Schottky barrier diodes. Rectification behaviour was observed for the isotype GaN/Si (n–n) heterojunction. Ideality factors and Schottky barrier heights for Ni and Cr Schottky barriers on GaN, were deduced to be 1.4 and 1.7; and 0.62 and 0.64 eV, respectively. DA - 2005/2// PY - 2005/2// DO - 10.1016/j.ssc.2004.11.022 VL - 133 IS - 5 SP - 283-287 J2 - Solid State Communications LA - en OP - SN - 0038-1098 UR - http://dx.doi.org/10.1016/j.ssc.2004.11.022 DB - Crossref KW - semiconductors KW - crystal growth KW - X-ray diffraction KW - electrical properties ER - TY - JOUR TI - Performance analysis of space-time transmitter diversity techniques for WCDMA using long range prediction AU - Guncavdi, S. AU - Duel-Hallen, A. T2 - IEEE Trans. Wirel. Commun. (USA) AB - Transmitter diversity in the downlink of code-division multiple-access (CDMA) systems achieves similar performance gains to the mobile-station receiver diversity without the complexity of a mobile-station receiver antenna array. Pre-RAKE precoding at the transmitter can be employed to achieve the multipath diversity without the need of the RAKE receiver at the mobile station. We examine feasibility of several transmitter diversity techniques and precoding for the third-generation wideband CDMA (WCDMA) systems. In particular, selective transmit diversity, transmit adaptive array and space-time pre-RAKE (STPR) techniques are compared. It is demonstrated that the STPR method is the optimal method to combine antenna diversity and temporal precoding. This method achieves the gain of maximum ratio combining of all space and frequency diversity branches when perfect channel state information is available at the transmitter. We employ the long range fading prediction algorithm to enable transmitter diversity techniques for rapidly time varying multipath fading channels. DA - 2005/1// PY - 2005/1// DO - 10.1109/TWC.2004.840222 VL - 4 IS - 1 SP - 40 - 5 UR - http://dx.doi.org/10.1109/TWC.2004.840222 KW - long range prediction KW - pre-RAKE KW - wideband code-division multiple-access (WCDMA) KW - selective transmit diversity (STD) KW - transmit adaptive array (Tx AA) KW - transmitter diversity ER - TY - CONF TI - Enabling adaptive modulation and interference mitigation for slow frequency hopping communications AU - Lei, M. AU - Duel-Hallen, A. AU - Hallen, H. C2 - 2005/// C3 - The Sixth IEEE International Workshop on Signal Processing Advances in Wireless Communications (IEEE Cat. No. 05EX992) CY - Piscataway, NJ, USA DA - 2005/// SP - 348 - 52 ER - TY - CONF TI - Performance Analysis of Tomlinson-Harashima Multiuser Precoding in Multipath CDMA Channels AU - Liu, J. AU - Duel-Hallen, A. C2 - 2005/7// C3 - Proc. 4GMF05 DA - 2005/7// ER - TY - JOUR TI - Intracranial vascular transfer function in acute stroke patients AU - Wu, Yang AU - An, Hongyu AU - Krim, Hamid AU - Vo, Katie AU - Lee, Jin-Moo AU - Lin, Weili T2 - Journal of Cerebral Blood Flow & Metabolism AB - Vascular transfer function (VTF) could potentially provide highly relevant physiological information, particularly in patients with cerebrovascular diseases. In this study, we aim to investigate potential alterations of intracranial VTF in patients with acute stroke. The widely employed dynamic susceptibility contrast (DSC) MR approach was employed to acquire images and spatial independent component analysis (ICA) was used to determine local arterial function (LAF) 1, reflecting MR signal changes resulted in the passage of the injected contrast. Subsequently, pixel-by-pixel VTF was derived through the deconvolution of the LAFs with a global artery function (GAF) obtained from the middle cerebral artery (MCA) using singular value decomposition (SVD). The ability to non-invasively depict VTF may offer new insights into blood flow related alterations in acute stroke patients. Perfusion images (PWI) were acquired using DSC from three healthy volunteers at 3 T and five acute stroke patients within 3-6 hrs from symptom onset at 1.5 T using a single shot T2*-weighted EPI sequence. In addition, diffusion-weighted (DWI) images were also acquired. GAF, Cga(t), was obtained through averaging contrast induced signal changes in the contralateral MCA with recirculation effects removed. The susceptibility related signal changes were converted to concentration curves. ICA analysis (ISP group, DTU, http://isp.imm.dtu.dk/toolbox) was applied to the concentration time curves throughout the entire brain 1. LAFs, Cla(x,t), were constructed based on both the spatial mappings and the temporal characteristics of the components, similar to that proposed in reference 1. Finally, VTF (T(x,t)) was obtained through SVD by deconvolving LAFs with GAF. In order to characterize how VTF differs between brain regions, DWI and PWI images were employed to define two region-of-interests (ROIs), namely, DWI-defined lesions and PWI/DWI mismatched regions while a normal ROI was defined in the contralateral hemisphere. In contrast, two ROIs were placed in the two hemispheres for the normal volunteers. Finally, the full-width-half-maximum (FWHM) and the power (EVTF) of the first harmonic of VTF were used to quantitatively determine the discrepancies between different ROIs. For comparison purposes, the ETVF obtained in stroke patients was normalized to that obtained from the normal volunteers. The FWHM obtained from normal volunteers is 5.8+/-0.2 s and 6.0+/-0.02 s, respectively, in the two ROIs. In contrast, for the stroke patients the DWI-defined lesions exhibit a much larger FWHM (9.0+/-8.8 s) while a similar FWHM was obtained for both the PWI/DWI mismatched regions (5.5+/-1.7 s) and the contralateral hemisphere (4.9+/-1.4 s) when compared with that obtained in normal subjects. In addition, the normalized power of the first harmonic of the VTF demonstrates that the DWI-defined lesion, PWI/DWI mismatched regions, and the contralateral hemisphere is 24.1+/-31.1%, 43.5+/-35.4%, and 153.5+/-103.8% with respect to that obtained in normal subjects, respectively. These findings suggest that the DWI-defined lesions exhibit the largest bolus dispersion and smallest power when compared with that obtained in the normal subjects as well as other brain regions in stroke patients. Although our study has a limited sample size, we have demonstrated a novel tool for obtaining VTF in acute stroke patients. DA - 2005/8// PY - 2005/8// DO - 10.1038/sj.jcbfm.9591524.0394 VL - 25 IS - 1_suppl SP - S394-S394 J2 - J Cereb Blood Flow Metab LA - en OP - SN - 0271-678X 1559-7016 UR - http://dx.doi.org/10.1038/sj.jcbfm.9591524.0394 DB - Crossref ER - TY - CONF TI - Code size efficiency in global scheduling for ILP processors AU - Zhou, Huiyang AU - Conte, T.M. T2 - Sixth Annual Workshop on Interaction between Compilers and Computer Architectures AB - In global scheduling for ILP processors, region-enlarging optimizations, especially tail duplication, are commonly used. The code size increase due to such optimizations, however, raises serious concerns about the affected I-cache and TLB performance. In this paper, we propose a quantitative measure of the code size efficiency at compile time for any code size related optimization. Then, based on the efficiency of tail duplication, we propose the solutions to two related problems: (1) how to achieve the best performance for a given code size increase, (2) how to get the optimal code size efficiency for any program. Our study shows that code size increase has a significant but varying impact on IPC, e.g., the first 2% code size increase results in 18.5% increase in static IPC, but less than 1% when the given code size further increases from 20% to 30%. We then use this feature to define the optimal code size efficiency and to derive a simple, yet robust threshold scheme finding it. The experimental results using SPECint95 benchmarks show that this threshold scheme finds the optimal efficiency accurately. While the optimal efficiency results show an average increase of 2% in code size, the improved I-cache performance is observed and a speedup of 17% over the natural treegion results is achieved. C2 - 2005/8/25/ C3 - Proceedings Sixth Annual Workshop on Interaction between Compilers and Computer Architectures DA - 2005/8/25/ DO - 10.1109/intera.2002.995845 PB - IEEE Comput. Soc SN - 0769515347 UR - http://dx.doi.org/10.1109/intera.2002.995845 DB - Crossref ER - TY - CONF TI - Detecting global stride locality in value streams AU - Zhou, Huiyang AU - Flanagan, J. AU - Conte, T.M. T2 - ISCA 2003: 30th International Symposium on Computer Architecture C2 - 2005/4/12/ C3 - 30th Annual International Symposium on Computer Architecture, 2003. Proceedings. DA - 2005/4/12/ DO - 10.1109/isca.2003.1207011 PB - IEEE Comput. Soc SN - 0769519458 UR - http://dx.doi.org/10.1109/isca.2003.1207011 DB - Crossref ER - TY - CONF TI - Dual-core execution: building a highly scalable single-thread instruction window AU - Zhou, Huiyang T2 - 14th International Conference on Parallel Architectures and Compilation Techniques (PACT'05) AB - Current integration trends embrace the prosperity of single-chip multi-core processors. Although multi-core processors deliver significantly improved system throughput, single-thread performance is not addressed. In this paper, we propose a new execution paradigm that utilizes multi-cores on a single chip collaboratively to achieve high performance for single-thread memory-intensive workloads while maintaining the flexibility to support multithreaded applications. The proposed execution paradigm, dual-core execution, consists of two superscalar cores (a front and back processor) coupled with a queue. The front processor fetches and preprocesses instruction streams and retires processed instructions into the queue for the back processor to consume. The front processor executes instructions as usual except for cache-missing loads, which produce an invalid value instead of blocking the pipeline. As a result, the front processor runs far ahead to warm up the data caches and fix branch mispredictions for the back processor. In-flight instructions are distributed in the front processor, the queue, and the back processor, forming a very large instruction window for single-thread out-of-order execution. The proposed architecture incurs only minor hardware changes and does not require any large centralized structures such as large register files, issue queues, load/store queues, or reorder buffers. Experimental results show remarkable latency hiding capabilities of the proposed architecture, even outperforming more complex single-thread processors with much larger instruction windows than the front or back processor. C2 - 2005/// C3 - 14th International Conference on Parallel Architectures and Compilation Techniques (PACT'05) DA - 2005/// DO - 10.1109/pact.2005.18 PB - IEEE SN - 076952429X UR - http://dx.doi.org/10.1109/pact.2005.18 DB - Crossref ER - TY - CONF TI - Study of global frequency dynamic behavior of large power systems AU - Tsai, S.-J.S. AU - Zhang, Li AU - Phadke, A.G. AU - Liu, Yilu AU - Ingram, M.R. AU - Bell, S.C. AU - Grant, I.S. AU - Bradshaw, D.T. AU - Lubkeman, D. AU - Tang, Le T2 - IEEE PES Power Systems Conference and Exposition, 2004. AB - A global view of power system's frequency behavior electromechanical wave phenomenon of power system opens up a new window for analyzing system dynamics. With the aid of global positioning system (GPS), measurements from different locations would have synchronous time; therefore a system-wide observation and analysis would be possible. As part of the US-wide power frequency monitoring network project (FNET), this paper focus on simulation study results of power frequency dynamics of major US systems (e.g. WSCC, Eastern US). The study assesses the frequency measurement accuracy needed to observe frequency oscillations from events such as remote generation drops. Electromechanical wave propagation phenomena during system disturbances have been observed. The speeds of electromechanical wave propagation in different areas of the US systems were estimated and their characteristics were discussed. Simulation of the 2003 August 14 northeastern US blackout is given as an example to show wide area monitoring systems such as FNET could have provided crucial information for possible remedial actions. C2 - 2005/4/19/ C3 - IEEE PES Power Systems Conference and Exposition, 2004. DA - 2005/4/19/ DO - 10.1109/psce.2004.1397518 PB - IEEE SN - 078038718X UR - http://dx.doi.org/10.1109/psce.2004.1397518 DB - Crossref ER - TY - CONF TI - Large scale storm outage management AU - Lubkeman, D. AU - Julian, D.E. T2 - 2004 IEEE Power Engineering Society General Meeting AB - This paper describes a process for improving information used by electric utilities for managing restoration of distribution facilities damaged by large-scale storms such as large-scale ice storms and hurricanes. The process is realized in the form of a decision support tool that utilizes the model of the distribution circuit layout, the placement of protective and switching devices and the location of customers to determine how crew resources should be allocated and managed for cost-effective storm outage management. Equipment damage predictions based on the severity and location of the weather are also used to predict where and to what extent circuit damage is likely to occur. Given crew availability and the maintenance crew requirement for each damage type, a storm outage algorithm predicts damage per feeder, area and region and calculates estimated time to restoration for each customer. After the storm hits additional information such as customer calls, switch status and field damage assessments are utilized by the storm outage algorithm to provide updated predictions of damage and estimated time to restore. C2 - 2005/4/12/ C3 - IEEE Power Engineering Society General Meeting, 2004. DA - 2005/4/12/ DO - 10.1109/pes.2004.1372741 PB - IEEE SN - 0780384652 UR - http://dx.doi.org/10.1109/pes.2004.1372741 DB - Crossref ER - TY - CONF TI - Automated Testing Of Solid-State Watthour Meters In The Presence Of Harmonic Distortion AU - Lubkeman, D.L. AU - Burnette, C. AU - Fortson, H. AU - Girgis, A.A. AU - Makram, E.B. T2 - ICHPS V International Conference on Harmonics in Power Systems. C2 - 2005/8/24/ C3 - Proceedings of the 5th International Conference on Harmonics in Power Systems (ICHPS V) DA - 2005/8/24/ DO - 10.1109/ichps.1992.559107 SP - 345–351 PB - IEEE UR - http://dx.doi.org/10.1109/ichps.1992.559107 ER - TY - JOUR TI - Optimal Throughput and Energy Efficiency for Wireless Sensor Networks: Multiple Access and Multipacket Reception AU - Li, Wenjun AU - Dai, Huaiyu T2 - EURASIP Journal on Wireless Communications and Networking AB - We investigate two important aspects in sensor network design—the throughput and the energy efficiency. We consider the uplink reachback problem where the receiver is equipped with multiple antennas and linear multiuser detectors. We first assume Rayleigh flat-fading, and analyze two MAC schemes: round-robin and slotted-ALOHA. We optimize the average number of transmissions per slot and the transmission power for two purposes: maximizing the throughput, or minimizing the effective energy (defined as the average energy consumption per successfully received packet) subject to a throughput constraint. For each MAC scheme with a given linear detector, we derive the maximum asymptotic throughput as the signal-to-noise ratio goes to infinity. It is shown that the minimum effective energy grows rapidly as the throughput constraint approaches the maximum asymptotic throughput. By comparing the optimal performance of different MAC schemes equipped with different detectors, we draw important tradeoffs involved in the sensor network design. Finally, we show that multiuser scheduling greatly enhances system performance in a shadow fading environment. DA - 2005/// PY - 2005/// DO - 10.1155/wcn.2005.541 VL - 2005 IS - 4 SP - 670575 J2 - EURASIP J Wirel Commun Netw LA - en OP - SN - 1687-1499 UR - http://dx.doi.org/10.1155/wcn.2005.541 DB - Crossref ER - TY - JOUR TI - A portable near infrared spectroscopy system for bedside monitoring of newborn brain AU - Bozkurt, Alper AU - Rosen, Arye AU - Rosen, Harel AU - Onaral, Banu T2 - BioMedical Engineering OnLine AB - Newborns with critical health conditions are monitored in neonatal intensive care units (NICU). In NICU, one of the most important problems that they face is the risk of brain injury. There is a need for continuous monitoring of newborn's brain function to prevent any potential brain injury. This type of monitoring should not interfere with intensive care of the newborn. Therefore, it should be non-invasive and portable.In this paper, a low-cost, battery operated, dual wavelength, continuous wave near infrared spectroscopy system for continuous bedside hemodynamic monitoring of neonatal brain is presented. The system has been designed to optimize SNR by optimizing the wavelength-multiplexing parameters with special emphasis on safety issues concerning burn injuries. SNR improvement by utilizing the entire dynamic range has been satisfied with modifications in analog circuitry.As a result, a shot-limited SNR of 67 dB has been achieved for 10 Hz temporal resolution. The system can operate more than 30 hours without recharging when an off-the-shelf 1850 mAh-7.2 V battery is used. Laboratory tests with optical phantoms and preliminary data recorded in NICU demonstrate the potential of the system as a reliable clinical tool to be employed in the bedside regional monitoring of newborn brain metabolism under intensive care. DA - 2005/// PY - 2005/// DO - 10.1186/1475-925x-4-29 VL - 4 IS - 29 SN - 1475-925X UR - http://dx.doi.org/10.1186/1475-925x-4-29 ER - TY - RPRT TI - Modeling and Control of an SOFC APU AU - Khaleel, M.A. AU - Sun, X. AU - Koeppel, B.J. AU - Nguyen, B.N. AU - Lu, N. A3 - Pacific Northwest National Laboratory DA - 2005/// PY - 2005/// M1 - PNNL-15396 PB - Pacific Northwest National Laboratory SN - PNNL-15396 ER - TY - CONF TI - Exchange Effects on Electronic States in QWs with e-h Plasma in an Electric Field AU - Fedorov, I.A. AU - Kim, K.W. AU - Sokolov, V.N. AU - Zavada, J.M. T2 - PHYSICS OF SEMICONDUCTORS: 27th International Conference on the Physics of Semiconductors - ICPS-27 AB - We study effects of electron‐hole (e‐h) plasma density N and a uniform electric field F on the ground and first excited eigenstates, energy levels and electron and hole wave functions, resulting from many‐particle (Hartree and exchange) Coulomb interactions in a 2D e‐h plasma. The coupled Schrödinger equations for electrons and holes are solved self‐consistently in the Hartree‐Fock approximation together with the Poisson equation. The solutions are analyzed treating N and F as independent parameters for quantum wells (QWs) with different width, dqw. The calculations demonstrate that with decreasing dqw and increasing N, the charge separation within the QW induced by the field becomes less effective and the relative contribution of the Hartree interactions to the energy level shifts is decreased. The results are applied to study possible bistable behavior of the QW electroabsorption under strong photoexcitation near the exciton resonance. C2 - 2005/// C3 - AIP Conference Proceedings DA - 2005/// DO - 10.1063/1.1994559 VL - 772 SP - 1234–1235, PB - AIP UR - http://dx.doi.org/10.1063/1.1994559 ER - TY - CONF TI - L-valley electrons in SiGe heterostructures: highly anisotropic and tunable Zeeman and Rashba-like spin splittings AU - Kiselev, A.A. AU - Baron, F.A. AU - Kim, K.W. AU - Wang, K.L. AU - Yablonovitch, E. AB - We have conducted a detailed and systematic analysis of Zeeman and Rashba‐like (structure‐asymmetry‐induced) spin splittings in SiGe heterostructures. The calculations were performed in the framework of a relevant kp model, developed specifically for the L point states of the group IV semiconductors. Effects of the alloy composition, crystallographic orientation, spatial confinement, strain, and electric field are accounted for and documented for a realistic structure design. Notable Rashba effect, considerable anisotropy and deviation of the g tensor components from their respective bulk values make the SiGe structures a friendly choice for the effective spin manipulation. C2 - 2005/// C3 - AIP Conference Proceedings DA - 2005/// DO - 10.1063/1.1994160 VL - 772 SP - 411–412, PB - AIP UR - http://dx.doi.org/10.1063/1.1994160 ER - TY - CONF TI - Analysis of the Δ(X) − L intervalley mixing in group-IV heterostructures AU - Kiselev, A.A. AU - Kim, K.W. AU - Yablonovitch, E. T2 - PHYSICS OF SEMICONDUCTORS: 27th International Conference on the Physics of Semiconductors - ICPS-27 AB - Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation A. A. Kiselev, K. W. Kim, E. Yablonovitch; Analysis of the Δ(X) − L intervalley mixing in group‐IV heterostructures. AIP Conf. Proc. 30 June 2005; 772 (1): 409–410. https://doi.org/10.1063/1.1994159 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAIP Publishing PortfolioAIP Conference Proceedings Search Advanced Search |Citation Search C2 - 2005/// C3 - AIP Conference Proceedings DA - 2005/// DO - 10.1063/1.1994159 VL - 772 SP - 409–410, PB - AIP UR - http://dx.doi.org/10.1063/1.1994159 ER - TY - JOUR TI - Thermoelectric power factor in semiconductors with buried epitaxial semimetallic nanoparticles AU - Zide, J. M. AU - Klenov, D. O. AU - Stemmer, S. AU - Gossard, A. C. AU - Zeng, G. AU - Bowers, J. E. AU - Vashaee, D. AU - Shakouri, A. T2 - Applied Physics Letters AB - We have grown composite epitaxial materials that consist of semimetallic ErAs nanoparticles embedded in a semiconducting In0.53Ga0.47As matrix both as superlattices and randomly distributed throughout the matrix. The presence of these particles increases the free electron concentration in the material while providing scattering centers for phonons. We measure electron concentration, mobility, and Seebeck coefficient of these materials and discuss their potential for use in thermoelectric power generators. DA - 2005/9/12/ PY - 2005/9/12/ DO - 10.1063/1.2043241 VL - 87 IS - 11 SP - 112102 J2 - Appl. Phys. Lett. LA - en OP - SN - 0003-6951 1077-3118 UR - http://dx.doi.org/10.1063/1.2043241 DB - Crossref ER - TY - CONF TI - Fabrication of wafer-scale, aligned Sub-25 nm nanowires and templates using Planar Edge Defined Alternate Layer (PEDAL) Process AU - Sonkusale, S AU - Amsinck, C.J. AU - Nackashi, D.P. AU - Di Spigna, N.H. AU - Barlage, D AU - Johnson, M AU - Franzon, P.D. T2 - 2005 NSTI Nanotechnology Conference and Trade Show C2 - 2005/5/8/ C3 - Technical Proceedings of the 2005 NSTI Nanotechnology Conference and Trade Show CY - Anaheim, CA DA - 2005/5/8/ PY - 2005/// SN - 0-9767985-2-2 ER - TY - CONF TI - 3Gb/s AC-coupled chip-to-chip communication using a low-swing pulse receiver AU - Luo, L. AU - Wilson, J.M. AU - Mick, S.E. AU - Xu, J. AU - Zhang, L. AU - Franzon, P.D. T2 - 2005 International Solid State Circuits Conference AB - A 3Gbit/s 60mV low-swing pulse receiver is presented for AC-coupled interconnect (ACCI). Using this receiver, we demonstrate without errors, chip-to-chip communication through an ACCI channel with 150fF coupling capacitors, across 15cm FR4 microstrip line. A test chip is fabricated in 0.18 /spl mu/m CMOS technology and the TX and RX dissipate 15mW per I/O at 3Gbit/s. C2 - 2005/// C3 - Proceedings of the 2005 International Solid State Circuits Conference CY - San Francisco, CA, USA DA - 2005/// PY - 2005/2/10/ DO - 10.1109/ISSCC.2005.1494099 SN - 0-7803-8904-2 ER - TY - CONF TI - An integrated self-masking technique for providing low-loss metallized RF MEMS devices in a polysilicon only MEMS process AU - Wilson, J. AU - Bashirullah, R. AU - Nackashi, D.P. AU - Winick, D.A. AU - Franzon, P.D. T2 - SPIE Micro Europe AB - A novel masking technique that enables the complex patterning of metal on any layer of a released MEMS chip is demonstrated. This technique enables a polysilicon only MEMS process to create low-loss RF devices. To illustrate the advantages of post-release metallization, in a polysilicon only MEMS process, a rotating MEMS tunable capacitor that provides a wide and linear tuning range is presented. The core of the design comes from high yield, mechanically proven gear designs from Sandia’s SUMMiT design library. Significant alterations were made to the gear structure to create the final device. Preliminary tests show device capacitance ratios of 1.8:1, with linear tuning. Increased metal deposition to reduce the device air gap, can produce a capacitance ratio over 6:1. C2 - 2005/// C3 - Proceedings of the SPIE Micro Europe CY - Sevilla, Spain DA - 2005/// PY - 2005/5// DO - 10.1117/12.607592 KW - RF MEMS KW - post process KW - metallization KW - tunable capacitor KW - removable mask KW - SUMMiT ER - TY - CONF TI - 2.8 Gbps inductively coupled interconnect for 3D ICs AU - Xu, J. AU - Wilson, J. AU - Mick, S. AU - Luo, L. C2 - 2005/6// C3 - Proceedings of the 2005 symposium on VLSI circuits DA - 2005/6// SP - 352–355 ER - TY - CONF TI - Impact of SOI research Project on microelectronics education: a case study AU - Dogan, N.S. AU - Franzon, P. AU - Liu, W. T2 - 2005 IEEE International Conference on Microelectronic Systems Education (MSE'05) AB - Microelectronics systems design is a collaborative, multidisciplinary activity, involving the combined efforts of system architects, circuit designers, device engineers, software developers, and process engineers. Semiconductor products are vital to today's $1 trillion/year electronic industry. There is a need for educational programs that prepare engineers for the semiconductor industry. This paper presents the impact of an RF-SoC research project on the career choices of students involved and its broader impact on the microelectronics education in the participating universities. Teaching students the design and test at the physical level is valuable in that it provides the understanding and skills they will need to perform these functions in their subsequent employment. C2 - 2005/// C3 - Proceedings of the IEEE International Conference on Microelectronics systems education CY - Anaheim, CA, USA DA - 2005/// PY - 2005/6/12/ DO - 10.1109/MSE.2005.35 SP - 33–34 PB - IEEE SN - 0-7695-2374-9 ER - TY - CHAP TI - Parallel computing environments and methods for power distribution system simulation AU - Lu, N. AU - Taylor, Z. T. AU - Chassin, D. P. AU - Guttromson, R. AU - Studham, S. AU - Ieee T2 - 2005 Ieee Power Engineering Society General Meeting, Vols, 1-3 PY - 2005/// SP - 215-220 PB - SE - UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000232799400033&KeyUID=WOS:000232799400033 ER - TY - CHAP TI - Modeling uncertainties in aggregated thermostatically controlled loads using a state queueing model AU - Lu, N. AU - Chassin, D. P. AU - Widergren, S. E. AU - Ieee T2 - 2005 Ieee Power Engineering Society General Meeting, Vols, 1-3 PY - 2005/// SP - 1336 PB - SE - UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000232799401061&KeyUID=WOS:000232799401061 ER - TY - JOUR TI - Modeling uncertainties in aggregated thermostatically controlled loads using a state queueing model AU - Lu, N. AU - Chassin, D. P. AU - Widergren, S. E. T2 - Ieee Transactions on Power Systems AB - To study the impacts of price responsive demand on the electric power system requires better load models. This paper discusses the modeling of uncertainties in aggregated thermostatically controlled loads using a state queueing (SQ) model. The cycling times of thermostatically controlled appliances (TCAs) vary with the TCA types and sizes, as well as the ambient temperatures. The random consumption of consumers, which shortens or prolongs a specific TCA cycling period, introduces another degree of uncertainty. By modifying the state transition matrix, these random factors can be taken into account in a discrete SQ model. The impacts of considering load diversity in the SQ model while simulating TCA setpoint response are also studied. DA - 2005/// PY - 2005/// DO - 10.1109/tpwrs.2005.846072 VL - 20 IS - 2 SP - 725-733 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000228778800025&KeyUID=WOS:000228778800025 KW - demand-side management program KW - load model KW - load synthesis KW - state queueing model KW - thermostatically controlled appliance KW - water heater load ER - TY - CHAP TI - Control strategies of thermostatically controlled appliances in a competitive electricity market AU - Lu, N. AU - Katipamula, S. AU - Ieee T2 - 2005 Ieee Power Engineering Society General Meeting, Vols, 1-3 PY - 2005/// SP - 202-207 PB - SE - UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000232799400031&KeyUID=WOS:000232799400031 ER - TY - JOUR TI - Configurable String Matching Hardware for Speeding Up Intrusion Detection AU - Aldwairi, Monther AU - Conte, Thomas AU - Franzon, Paul T2 - SIGARCH Comput. Archit. News AB - Signature-based Intrusion Detection Systems (IDSs) monitor network traffic for security threats by scanning packet payloads for attack signatures. IDSs have to run at wire speed and need to be configurable to protect against emerging attacks. In this paper we consider the problem of string matching which is the most computationally intensive task in IDS. A configurable string matching accelerator is developed with the focus on increasing throughput while maintaining the configurability provided by the software IDSs. Our preliminary results suggest that the hardware accelerator offers an overall system performance of up to 14Gbps. DA - 2005/// PY - 2005/// DO - 10.1145/1055626.1055640 VL - 33 IS - 1 SP - 99–107 ER - TY - CONF TI - Molecular electronic latches and memories AU - Nackashi, D.P. AU - Amsinck, C.J. AU - DiSPigna, N.H. AU - Franzon, P.D. AB - Many two terminal molecular devices functioning as diodes have been synthesized with responses similar to solid state devices such as rectifying and resonant tunneling diodes. In this paper, the feasibility of integrating these molecular diodes into current circuit architectures is explored. A bistable latch and memory architecture are simulated using IV data from the 2'-amino-4-ethynylphenyl-4'-ethynylphenyl-5'-nitro-1-bensenethiolate molecule previously published by the Reed group at Yale University. HSPICE simulation results are used to illustrate the performance of a bistable latch and a memory array. C2 - 2005/7/11/ C3 - IEEE Nano DA - 2005/7/11/ DO - 10.1109/nano.2005.1500658 SP - 819–822 ER - TY - CONF TI - Molecular electronics – devices and circuits technology AU - Franzon, P. AU - Nackashi, D. AU - DiSpigna, N. AU - Sonkusale, S. C2 - 2005/// C3 - Proceedings IFIP VLSI-SoC 2005 DA - 2005/// SP - 57–63 ER - TY - CONF TI - Integrated ultrasound imaging systems based on capacitive micromachined ultrasonic transducer arrays AU - Wygant, I.O. AU - Yeh, D.T. AU - Zhuang, X. AU - Vaithilingam, S. AU - Nikoozadeh, A. AU - Oralkan, Ö. AU - Ergun, A.S. AU - Yaralioglu, G.G. AU - Khuri-Yakub, B.T. C2 - 2005/// C3 - Proceedings of the IEEE Conference on Sensors DA - 2005/// SP - 704–707 ER - TY - CONF TI - 2.8 Gb/s Inductively Coupled Interconnect for 3-D ICs AU - Xu, J. AU - Wilson, J. AU - Mick, S. AU - Luo, L. AU - Franzon, P. C2 - 2005/6// C3 - Japan VLSI Symposium DA - 2005/6// ER - TY - CONF TI - The feasibility of on-chip interconnection using antennas AU - O, K.K. AU - Kim, K. AU - Floyd, B. T2 - IEEE/ACM International Conference on Computer-Aided Design C2 - 2005/11// DA - 2005/11// SP - 979–984 ER - TY - CONF TI - A miniature real-time volumetric ultrasound imaging system AU - Wygant, Ira O. AU - Yeh, David T. AU - Zhuang, Xuefeng AU - Nikoozadeh, Amin AU - Oralkan, Omer AU - Ergun, Arif S. AU - Karaman, Mustafa AU - Khuri-Yakub, Butrus T. T2 - Medical Imaging A2 - Walker, William F. A2 - Emelianov, Stanislav Y. AB - Progress made in the development of a miniature real-time volumetric ultrasound imaging system is presented. This system is targeted for use in a 5-mm endoscopic channel and will provide real-time, 30-mm deep, volumetric images. It is being developed as a clinically useful device, to demonstrate a means of integrating the front-end electronics with the transducer array, and to demonstrate the advantages of the capacitive micromachined ultrasonic transducer (CMUT) technology for medical imaging. Presented here is the progress made towards the initial implementation of this system, which is based on a two-dimensional, 16x16 CMUT array. Each CMUT element is 250 um by 250 um and has a 5 MHz center frequency. The elements are connected to bond pads on the back side of the array with 400-um long through-wafer interconnects. The transducer array is flip-chip bonded to a custom-designed integrated circuit that comprises the front-end electronics. The result is that each transducer element is connected to a dedicated pulser and low-noise preamplifier. The pulser generates 25-V, 100-ns wide, unipolar pulses. The preamplifier has an approximate transimpedance gain of 500 kOhm and 3-dB bandwidth of 10 MHz. In the first implementation of the system, one element at a time can be selected for transmit and receive and thus synthetic aperture images can be generated. In future implementations, 16 channels will be active at a given time. These channels will connect to an FPGA-based data acquisition system for real-time image reconstruction. C2 - 2005/4/12/ C3 - Medical Imaging 2005: Ultrasonic Imaging and Signal Processing DA - 2005/4/12/ DO - 10.1117/12.596019 PB - SPIE UR - http://dx.doi.org/10.1117/12.596019 DB - Crossref KW - capacitive micromachined ultrasonic transducer KW - CMUT KW - two-dimensional array KW - electronics KW - ultrasonic imaging KW - integration KW - synthetic aperture KW - flip-chip bonding KW - through-wafer interconnects KW - systems ER - TY - CONF TI - Underwater acoustic imaging using capacitive micromachined ultrasonic transducer arrays AU - Oralkan, O. AU - Ergun, A.S. AU - Cheng, C.-H. AU - Johnson, J.A. AU - Karaman, M. AU - Khuri-Yakub, B.T. T2 - Oceans 2002 Conference and Exhibition. AB - Capacitive micromachined ultrasonic transducers (CMUTs) have recently emerged as an alternative technology to piezoelectric transducers, offering advantages such as wide bandwidth, ease of fabricating large arrays and potential for integration with electronic circuits. In this paper, we present 2D and 3D pulse-echo imaging results using ID linear and 2D rectangular CMUT arrays, respectively. The aim of this paper is to demonstrate the viability of CMUTs for underwater acoustic imaging. For imaging experiments, we have fabricated ID and 2D CMUT arrays, and built an experimental setup allowing us to transmit and receive ultrasound signals from individual transducer elements. The image quality obtained shows that CMUTs are a strong alternative to conventional piezoelectric transducer arrays for the design of future generations of underwater acoustic imaging systems. C2 - 2005/8/25/ C3 - Oceans '02 MTS/IEEE DA - 2005/8/25/ DO - 10.1109/oceans.2002.1191996 PB - IEEE SN - 0780375343 UR - http://dx.doi.org/10.1109/oceans.2002.1191996 DB - Crossref ER - TY - CONF TI - CMUT ring arrays for forward-looking intravascular imaging AU - Oralkan, O. AU - Hansen, S.T. AU - Bayram, B. AU - Yaralioglu, G.G. AU - Ergun, A.S. AU - Khuri-Yakub, B.T. T2 - IEEE Ultrasonics Symposium, 2004 AB - The paper describes an annular CMUT ring array designed and fabricated for the tip of a catheter used for forward-looking intravascular imaging. A 64-element, 2-mm average diameter array was fabricated as an experimental prototype. A single element in the array is connected to a single-channel custom front-end integrated circuit for pulse-echo operation. In conventional operation, the transducer operates at around 10 MHz. In the collapsed regime, the operating frequency shifts to 25 MHz and the received echo amplitude is tripled. The SNR is measured as 23 dB in a 50-MHz measurement bandwidth for an echo signal from a plane reflector at 1.5 mm. We also performed a nonlinear dynamic transient finite element analysis for the transducer, and found these results to be in good agreement with experimental measurements, both for conventional and collapsed operation. C2 - 2005/4/19/ C3 - IEEE Ultrasonics Symposium, 2004 DA - 2005/4/19/ DO - 10.1109/ultsym.2004.1417748 PB - IEEE SN - 0780384121 UR - http://dx.doi.org/10.1109/ultsym.2004.1417748 DB - Crossref ER - TY - CONF TI - High-frequency CMUT arrays for high-resolution medical imaging AU - Oralkan, O. AU - Hansen, S.T. AU - Bayram, B. AU - Yaralglu, G.G. AU - Ergun, A.S. AU - Khuri-Yakub, B.T. T2 - IEEE Ultrasonics Symposium, 2004 AB - The paper describes high-frequency 1D CMUT arrays designed and fabricated for use in electronically scanned high-resolution ultrasonic imaging systems. Two different designs of 64-element linear CMUT arrays are presented. A single element in each array is connected to a single-channel custom front-end integrated circuit for pulse-echo operation. The first design has a resonant frequency of 43 MHz in air, and operates at 30 MHz in immersion. The second design exhibits a resonant frequency of 60 MHz in air, and operates at 45 MHz in immersion. Experimental results are compared to simulation results obtained from the equivalent circuit model and nonlinear dynamic finite element analysis; a good agreement is observed between these results. The paper also briefly discusses the effects of the area fill factor on the frequency characteristics of CMUTs, which reveals that the transducer active area should be maximized to obtain a wideband response at high frequencies. C2 - 2005/4/19/ C3 - IEEE Ultrasonics Symposium, 2004 DA - 2005/4/19/ DO - 10.1109/ultsym.2004.1417747 PB - IEEE SN - 0780384121 UR - http://dx.doi.org/10.1109/ultsym.2004.1417747 DB - Crossref ER - TY - CONF TI - Integrated ultrasonic imaging systems based on CMUT arrays: recent progress AU - Wygant, I.O. AU - Zhuang, X. AU - Yeh, D.T. AU - Nikoozadeh, A. AU - Oralkan, O. AU - Ergun, A.S. AU - Karaman, M. AU - Khuri-Yakub, B.T. T2 - IEEE Ultrasonics Symposium, 2004 AB - The paper describes the development of an ultrasonic imaging system based on a two-dimensional capacitive micromachined ultrasonic transducer (CMUT) array. The transducer array and front-end electronics are designed to fit in a 5-mm endoscopic channel. A custom-designed integrated circuit, which comprises the front-end electronics, is connected with the transducer elements via through-wafer interconnects and flip-chip bonding. FPGA-based signal-processing hardware provides real-time three-dimensional imaging. The imaging system is being developed to demonstrate a means of integrating the front-end electronics with the transducer array and to provide a clinically useful technology. Integration of the electronics can improve signal-to-noise ratio, reduce the number of cables connecting the imaging probe to a separate processing unit, and provide a means of connecting electronics to large two-dimensional transducer arrays. The paper describes the imaging system architecture and the progress we have made on implementing each of its components: a 16/spl times/16 CMUT array; custom-designed integrated circuits; a flip-chip bonding technique; signal-processing hardware. C2 - 2005/4/19/ C3 - IEEE Ultrasonics Symposium, 2004 DA - 2005/4/19/ DO - 10.1109/ultsym.2004.1417745 PB - IEEE SN - 0780384121 UR - http://dx.doi.org/10.1109/ultsym.2004.1417745 DB - Crossref ER - TY - CONF TI - Dynamic FEM analysis of multiple cmut cells in immersion AU - Bayram, B. AU - Yaralioglu, G.G. AU - Ergun, A.S. AU - Oralkan, O. AU - Khuri-Yakub, B.T. T2 - IEEE Ultrasonics Symposium, 2004 AB - This paper reports on the accurate modeling of immersion capacitive micromachined ultrasonic transducers (cMUTs) using a time-domain, nonlinear FEM package. A cMUT device consists of many cells. In this paper, a square membrane was used as the unit cell to cover the transducer area by periodic replication on the surface. The FEM calculations were used to analyze the nonlinear operation regimes of the cMUT. Nonlinear operation regimes (collapsed and collapse-snapback) provided higher acoustic output pressures than the conventional operation. The FEM calculations were compared to transmit experiment results performed with a hydrophone, and good agreement was observed. C2 - 2005/4/19/ C3 - IEEE Ultrasonics Symposium, 2004 DA - 2005/4/19/ DO - 10.1109/ultsym.2004.1417714 PB - IEEE SN - 0780384121 UR - http://dx.doi.org/10.1109/ultsym.2004.1417714 DB - Crossref ER - TY - CONF TI - Two-dimensional capacitive micromachined ultrasonic transducer (CMUT) arrays for a miniature integrated volumetric ultrasonic imaging system AU - Zhuang, Xuefeng AU - Wygant, Ira O. AU - Yeh, David T. AU - Nikoozadeh, Amin AU - Oralkan, Omer AU - Ergun, Arif S. AU - Cheng, Ching-Hsiang AU - Huang, Yongli AU - Yaralioglu, Goksen G. AU - Khuri-Yakub, Butrus T. AU - al. T2 - Medical Imaging A2 - Walker, William F. A2 - Emelianov, Stanislav Y. AB - We have designed, fabricated, and characterized two-dimensional 16x16-element capacitive micromachined ultrasonic transducer (CMUT) arrays. The CMUT array elements have a 250-μm pitch, and when tested in immersion, have a 5 MHz center frequency and 99% fractional bandwidth. The fabrication process is based on standard silicon micromachining techniques and therefore has the advantages of high yield, low cost, and ease of integration. The transducers have a Si3N4 membrane and are fabricated on a 400-μm thick silicon substrate. A low parasitic capacitance through-wafer via connects each CMUT element to a flip-chip bond pad on the back side of the wafer. Each through wafer via is 20 μm in diameter and 400 μm deep. The interconnects form metal-insulator-semiconductor (MIS) junctions with the surrounding high-resistivity silicon substrate to establish isolation and to reduce parasitic capacitance. Each through-wafer via has less than 0.06 pF of parasitic capacitance. We have investigated a Au-In flip-chip bonding process to connect the 2D CMUT array to a custom integrated circuit (IC) with transmit and receive electronics. To develop this process, we fabricated fanout structures on silicon, and flip-chip bonded these test dies to a flat surface coated with gold. The average series resistance per bump is about 3 Ohms, and 100% yield is obtained for a total of 30 bumps. C2 - 2005/4/12/ C3 - Medical Imaging 2005: Ultrasonic Imaging and Signal Processing DA - 2005/4/12/ DO - 10.1117/12.594702 PB - SPIE UR - http://dx.doi.org/10.1117/12.594702 DB - Crossref KW - capacitive micromachined ultrasonic transducer KW - CMUT KW - two-dimensional array KW - ultrasonic imaging KW - through-wafer interconnect KW - integration KW - flip-chip bonding ER - TY - CONF TI - High-frequency CMUT arrays for high-resolution medical imaging AU - Yeh, David T. AU - Oralkan, Omer AU - Ergun, Arif S. AU - Zhuang, Xuefeng AU - Wygant, Ira O. AU - Khuri-Yakub, Butrus T. T2 - Medical Imaging A2 - Walker, William F. A2 - Emelianov, Stanislav Y. AB - Applications of ultrasonic imaging in fields such as dermatology, ophthalmology, and cardiovascular medicine require very high resolution. Limitations in existing transducer technologies inhibit the development of high-frequency arrays, which would allow the use of dynamic focusing and enable higher frame rates. As an alternative, capacitive micromachined ultrasonic transducer (CMUT) technology, using integrated circuit fabrication techniques, can provide arrays with the small dimensions required for high-frequency operation. We have designed and fabricated several linear and ring arrays of CMUTs to operate in the 10 to 50 MHz range. These new arrays are made with the wafer bonding process. The ring arrays in particular demonstrate the feasibility of thinning the transducer to aid packaging in intravascular applications. This study shows that CMUTs can be made for high-frequency operation. Both transducers for use in conventional and collapse-mode operation have been designed and characterized. The results demonstrate that CMUT is an appropriate technology for building high-frequency arrays. A linear array of high-voltage pulser and amplifier circuits has also been designed for use with an array of CMUTs to enable real-time imaging applications. Pulse-echo results from the sixteen-channel array have been demonstrated. C2 - 2005/4/12/ C3 - Medical Imaging 2005: Ultrasonic Imaging and Signal Processing DA - 2005/4/12/ DO - 10.1117/12.595918 PB - SPIE UR - http://dx.doi.org/10.1117/12.595918 DB - Crossref KW - capacitive micromachined ultrasonic transducer KW - CMUT KW - high-frequency ultrasound KW - ring array ER - TY - CONF TI - Capacitive micromachined ultrasonic transducer technology for medical ultrasound imaging AU - Ergun, Arif S. AU - Zhuang, Xuefeng AU - Huang, Yongli AU - Oralkan, Omer AU - Yaralioglu, Goksen G. AU - Khuri-Yakub, Butrus T. T2 - Medical Imaging A2 - Walker, William F. A2 - Emelianov, Stanislav Y. AB - Capacitive micromachined ultrasonic transducer (cMUT) technology has been recognized as an attractive alternative to the more traditional piezoelectric transducer technology in medical ultrasound imaging for several years now. There are mainly two reasons for the interest in this technology: Micromachining is derived from the integrated circuit technology and therefore shares the well-known advantages and experience of it. Also, capacitive transduction using thin membranes has fundamental superiorities over the piezoelectric transduction mechanism such as wide frequency bandwidth. Capacitive micromachined ultrasonic transducers are essentially capacitor cells where the two plates of the capacitor, the membrane and the substrate, are separated with a vacuum sealed cavity. Typically, a cMUT is made of many micro-scale capacitor cells operating in parallel. This paper describes a new fabrication technique for building cMUTs which is called the wafer-bonding method. In this method, the cavity and the membrane are defined on separate wafers and brought together by wafer-bonding in vacuum. The wafer-bonding method has several advantages over the traditional sacrificial release method of cMUT fabrication. It allows greater flexibility in the cMUT design which means better device performance. It reduces the number of process steps, device turn-around time, and increases the overall uniformity, reliability. and repeatability. Device examples of one-dimensional and two-dimensional arrays designed to work in the 1 to 50 MHz range with 100% fractional bandwidth highlight the advantages of this method, and show that cMUT technology is indeed the better candidate for next generation ultrasonic imaging arrays. C2 - 2005/4/12/ C3 - Medical Imaging 2005: Ultrasonic Imaging and Signal Processing DA - 2005/4/12/ DO - 10.1117/12.595692 PB - SPIE UR - http://dx.doi.org/10.1117/12.595692 DB - Crossref KW - capacitive micromachined ultrasonic transducer KW - two-dimensional array KW - ultrasonic imaging KW - wafer bonding ER - TY - CONF TI - Electrical Characterization of Transmission Lines on Nonwoven Textile Substrates AU - Merritt, C.R. AU - Karaguzel, B. AU - Kang, T.-H. AU - Wilson, J. AU - Franzon, P.D. AU - Pourdeyhimi, B. AU - Nagle, H.T. AU - Grant, E. T2 - Materials Research Society 2005 Spring Meeting C2 - 2005/// DA - 2005/// ER - TY - CONF TI - Using Conductive Inks and Non-Woven Textiles for Wearable Computing AU - Karaguzel, B. AU - Merritt, C.R. AU - Kang, T.-H. AU - Wilson, J.M. AU - Franzon, P.D. AU - Nagle, H.T. AU - Grant, E. AU - Pourdeyhimi, B. T2 - The Textile Institute 84th Annual World Conference C2 - 2005/// DA - 2005/// ER - TY - CONF TI - Electrode Fabrication - NSF/ERC Core Unit B.2 AU - Ash, B. AU - Massoud, H.Z. AU - Nagle, H.T. AU - Wortman, J.J. T2 - [1990] Twelfth Annual International Conference of the IEEE Engineering in Medicine and Biology Society AB - The Electrode Fabrication Core Unit of the Duke/NC NSF Engineering Research Center in Emerging Cardiovascular Technologies focuses on the development and fabrication of plunge, surface, and three-dimensional electrode arrays for measuring biopotentials. This core unit is adapting existing semiconductor and microelectronics technology to produce the arrays needed for potential electrodes in basic arrhythmia studies and as mounting substrates for ionselective and bio-selective chemical sensors. VISION AND SIGNIFICANCE The purpose of the Electrode Fabrication Core Unit B.2 is to use integrated-circuit technology in the design, fabrication, and testing of novel microelectrode arrays needed to support research in cardiovascular technologies, such as for the Bioelectric Stimulation Unit 1.1 to detect in-vivo post ventricular fibrillation of the myocardium. The core is also building substrates for Core B.l Chemical Sensors and Unit 1.2B Vascular Diagnostic Systems. The technological focus of this core is to introduce, advance, and integrate existing technologies in the semiconductor and microelectronics industries in their application toward the design and fabrication of new electrode structures. By optimizing collaborations with other centers and industry, we expect to extend the state-of-the-art in cardiac sensor technology by demonstrating reliable, mass producible sensors for cardiac potentials and ionic metabolites with major applications in implantable defibrillators and cardiovascular monitoring. C2 - 2005/8/24/ C3 - [1990] Proceedings of the Twelfth Annual International Conference of the IEEE Engineering in Medicine and Biology Society DA - 2005/8/24/ DO - 10.1109/iembs.1990.691279 PB - IEEE SN - 0879425598 UR - http://dx.doi.org/10.1109/iembs.1990.691279 DB - Crossref ER - TY - CONF TI - Integrated dynamic body contact for H-gate PD-SOI MOSFETs for high performance/low power AU - Damiano, J. AU - Franzon, P.D. T2 - 2004 IEEE International SOI Conference AB - This paper discusses on the integrated dynamic body contact for H-gate PD-SOI MOSFETs for high performance/low power. PD-SOI circuit designers often must explicitly account for the MOSFET body voltage. Here, a dynamic body bias is implemented with a compact layout style to achieve improved performance and reduced power consumption. C2 - 2005/3/7/ C3 - 2004 IEEE International SOI Conference (IEEE Cat. No.04CH37573) DA - 2005/3/7/ DO - 10.1109/soi.2004.1391580 PB - IEEE SN - 0780384970 UR - http://dx.doi.org/10.1109/soi.2004.1391580 DB - Crossref ER - TY - CONF TI - Inductively Coupled Board-to-Board Connectors AU - Chandrasekar, K. AU - Feng, Zhiping AU - Wilson, J. AU - Mick, S. AU - Franzon, P. T2 - 2005 55th Electronic Components and Technology Conference AB - This paper discusses the potential application of inductive coupling elements as backplane connectors. Tradeoffs in the choice of inductive elements are discussed and a simple circuit model for electrically large board-to-board transformers is presented. Measured data for a 10mm outer diameter transformer shows an acceptable eye opening for 400Mbps NRZ data, and over 1GHz of bandwidth in the frequency domain. We also discuss how inductive connectors could find application in future long range FR4 backplanes C2 - 2005/7/28/ C3 - Proceedings Electronic Components and Technology, 2005. ECTC '05. CY - Lake Buena Vista, FL, USA DA - 2005/7/28/ PY - 2005/5/31/ DO - 10.1109/ectc.2005.1441411 SP - 1109–1113 PB - IEEE SN - 0780389069 UR - http://dx.doi.org/10.1109/ectc.2005.1441411 DB - Crossref ER - TY - CONF TI - Drive circuit for a mode conversion rotary ultrasonic motor AU - Xu, J. AU - Grant, E. AU - Kingon, A.I. AU - Wilson, J.M. AU - Franzon, P.D. T2 - 31st Annual Conference of IEEE Industrial Electronics Society, 2005. IECON 2005. AB - A mode conversion rotary ultrasonic motor (USM) has potential applications in miniature robotics. However, its electrical drive circuit presents some unique challenges, particularly in producing a high frequency (/spl sim/40 kHz), high voltage (/spl sim/200 V peak-to-peak) signal into a low impedance (/spl sim/100 /spl Omega/) capacitive motor, while achieving high efficiency. This paper describes the design of such a drive circuit, intended for use with a 12 V battery. The drive circuit consists of a switch-mode power converter driving the USM via a step-up planar transformer. Compensation and resonant elements are added to improve the power efficiency. While the peak efficiency of this circuit is 45%, in practice the equivalent impedance of the USM changes with mechanical load and temperature, resulting in an average efficiency of 16%. The admittance vs. frequency characteristic and the equivalent electrical model for a USM prototype are also presented in this paper. The circuit simulations and loaded testing of a full-bridge DC-AC resonant converter with DC-offset module were performed. A load-adapted frequency tracking method has also been proposed to improve the efficiency and stability of the drive circuit. C2 - 2005/// C3 - 31st Annual Conference of IEEE Industrial Electronics Society, 2005. IECON 2005. DA - 2005/// DO - 10.1109/iecon.2005.1569141 PB - IEEE SN - 0780392523 UR - http://dx.doi.org/10.1109/iecon.2005.1569141 DB - Crossref ER - TY - CONF TI - Driver pre-emphasis techniques for on-chip global buses AU - Zhang, Liang AU - Wilson, John AU - Bashirullah, Rizwan AU - Luo, Lei AU - Xu, Jian AU - Franzon, Paul T2 - the 2005 international symposium AB - By using current-sensing differential buses with driver pre-emphasis techniques, power dissipation is reduced by 26.0% - 51.2% and peak current is reduced by 63.8%, compared to conventional repeater insertion techniques, for 10mm long buses in TSMC 0.25μm technology. This proposed architecture lowers the worst coupling capacitance to total capacitance ratio to 14.4%. It only requires 7.9% more bus routing area than single-ended designs for a 16-bit bus, and saves all of the repeater placement blockages. To further verify that the driver pre-emphasis techniques can also be applied to voltage-mode single-ended buses, a test chip in TSMC 0.18μm technology was fabricated and measured C2 - 2005/// C3 - Proceedings of the 2005 international symposium on Low power electronics and design - ISLPED '05 DA - 2005/// DO - 10.1145/1077603.1077650 PB - ACM Press SN - 1595931376 UR - http://dx.doi.org/10.1145/1077603.1077650 DB - Crossref ER - TY - RPRT TI - Analysis of the DCS One-Stage Greedy Algorithm for Common Sparse Supports AU - Sarvotham, S. AU - Wakin, M.B. AU - Baron, D. AU - Duarte, M.F. AU - Baraniuk, R.G. A3 - Electrical and Computer Engineering Department, Rice University DA - 2005/10// PY - 2005/10// M1 - ECE-05-03 M3 - Technical Report PB - Electrical and Computer Engineering Department, Rice University SN - ECE-05-03 ER - TY - CONF TI - Non-Asymptotic Performance of Symmetric Slepian-Wolf Coding AU - Sarvotham, S. AU - Baron, D. AU - Baraniuk, R.G. T2 - CISS 2005 C2 - 2005/3// C3 - Proceedings of 39th Annual Conference on Information Sciences and Systems DA - 2005/3// ER - TY - CONF TI - Variable-Rate Coding with Feedback for Universal Communication Systems AU - Sarvotham, S. AU - Baron, D. AU - Baraniuk, R.G. C2 - 2005/9// C3 - Proceedings of 43d Allerton Conference on Communication, Control, and Computing DA - 2005/9// ER - TY - CONF TI - An Information-Theoretic Approach to Distributed Compressed Sensing AU - Baron, D. AU - Duarte, M.F. AU - Sarvotham, S. AU - Wakin, M.B. AU - Baraniuk, R.G. C2 - 2005/9// C3 - Proceedings of 43d Allerton Conference on Communication, Control, and Computing DA - 2005/9// ER - TY - CONF TI - Joint Sparsity Models for Distributed Compressed Sensing AU - Duarte, M.F. AU - Sarvotham, S. AU - Wakin, M.B. AU - Baron, D. AU - Baraniuk, R.G. T2 - SPARS C2 - 2005/11// C3 - Online Proceedings of the Workshop on Signal Processing with Adaptive Sparse Structured Representations DA - 2005/11// ER - TY - CONF TI - Recovery of Jointly Sparse Signals from Few Random Projections AU - Wakin, M.B. AU - Sarvotham, S. AU - Duarte, M.F. AU - Baron, D. AU - Baraniuk, R.G. C2 - 2005/12// C3 - Proceedings of Workshop on Neural Information Processing Systems DA - 2005/12// ER - TY - CONF TI - How quickly can we approach channel capacity? AU - Baron, D. AU - Khojastepour, M.A. AU - Baraniuk, R.G. T2 - Conference Record of the Thirty-Eighth Asilomar Conference on Signals, Systems and Computers, 2004. AB - Recent progress in code design has made it crucial to understand how quickly communication systems can approach their limits. To address this issue for the channel capacity C, we define the nonasymptotic capacity C/sub NA/(n, /spl epsi/) as the maximal rate of codebooks that achieve a probability /spl epsi/ of codeword error while using codewords of length n. We prove for the binary symmetric channel that C/sub NA/(n,/spl epsi/)=C-K(/spl epsi/)//spl radic/n+o(1//spl radic/n), where K(/spl epsi/) is available in closed form. We also describe similar results for the Gaussian channel. These results may lead to more efficient resource usage in practical communication systems. C2 - 2005/3/31/ C3 - Conference Record of the Thirty-Eighth Asilomar Conference on Signals, Systems and Computers, 2004. DA - 2005/3/31/ DO - 10.1109/acssc.2004.1399310 PB - IEEE SN - 0780386221 UR - http://dx.doi.org/10.1109/acssc.2004.1399310 DB - Crossref ER - TY - CONF TI - MM-wave transceivers using SiGe HBT technology AU - Gaucher, B. AU - Beukema, T. AU - Reynolds, S. AU - Floyd, B. AU - Zwick, T. AU - Pfeiffer, U. AU - Liu, D. AU - Cressler, J. T2 - Digest of Papers. 2004 Topical Meeting onSilicon Monolithic Integrated Circuits in RF Systems, 2004. AB - High-speed wireless technology has been evolving with roughly 2/spl times/ speed improvements every 18 months. Currently the wireless local-area network (WLAN) and wireless personal-area network (WPAN) spaces are developing new standards to increase wireless speeds beyond the 10-54 Mbit/s achieved in the first and second generation IEEE wireless network standards. Challenging issues which must be addressed in these new high-rate standards include FCC restrictions on maximum radiated power and power spectral density, bandwidth limitations in the available 2.4 and 5 GHz ISM bands, and cost and power required to support the high date rates in portable devices. This paper discusses the realization of a mm-wave transceiver in advanced SiGe HBT technology for application in high-speed mm-wave wireless systems. A low-power, integrated 60 GHz transceiver opens up the potential for economical high-speed wireless systems which can take advantage of >5 GHz of unlicensed spectrum available in the 60 GHz ISM band. C2 - 2005/3/31/ C3 - Digest of Papers. 2004 Topical Meeting onSilicon Monolithic Integrated Circuits in RF Systems, 2004. DA - 2005/3/31/ DO - 10.1109/smic.2004.1398172 PB - IEEE SN - 0780387031 UR - http://dx.doi.org/10.1109/smic.2004.1398172 DB - Crossref ER - TY - CONF TI - SiGe transformer matched power amplifier for operation at millimeter-wave frequencies AU - Pfeiffer, U.R. AU - Goren, D. AU - Floyd, B.A. AU - Reynolds, S.K. T2 - 31st European Solid-State Circuits Conference, 2005. ESSCIRC 2005. AB - In this paper, a transformer matched power amplifier for operation at millimeter-wave frequencies is presented. The SiGe single-stage push-pull amplifier uses a stacked transformer above a ground shield for output matching. The millimeter-wave transformer has a high coupling factor k = 0.8 and provides a very compact circuit layout. At 61.5 GHz the class-AB biased amplifier achieves a power gain of 12 dB with 8.5 dBm output power at a 1 dB compression. The saturated output power was measured up to P/sub sat/ = 14 dBm with a maximum PAE of 4.2%. C2 - 2005/12/10/ C3 - Proceedings of the 31st European Solid-State Circuits Conference, 2005. ESSCIRC 2005. DA - 2005/12/10/ DO - 10.1109/esscir.2005.1541579 SP - 141-144 PB - IEEE SN - 0780392051 UR - http://dx.doi.org/10.1109/esscir.2005.1541579 DB - Crossref ER - TY - JOUR TI - Antisequential Suffix Sorting for BWT-Based Data Compression AU - Baron, D. AU - Bresler, Y. T2 - IEEE Transactions on Computers AB - Suffix sorting requires ordering all suffixes of all symbols in an input sequence and has applications in running queries on large texts and in universal lossless data compression based on the Burrows Wheeler transform (BWT). We propose a new suffix lists data structure that leads to three fast, antisequential, and memory-efficient algorithms for suffix sorting. For a length-N input over a size-|X| alphabet, the worst-case complexities of these algorithms are /spl Theta/(N/sup 2/), O(|X|N log(N/|X|)), and O(N/spl radic/|X|log(N/|X|)), respectively. Furthermore, simulation results indicate performance that is competitive with other suffix sorting methods. In contrast, the suffix sorting methods that are fastest on standard test corpora have poor worst-case performance. Therefore, in comparison with other suffix sorting methods, suffix lists offer a useful trade off between practical performance and worst-case behavior. Another distinguishing feature of suffix lists is that these algorithms are simple; some of them can be implemented in VLSI. This could accelerate suffix sorting by at least an order of magnitude and enable high-speed BWT-based compression systems. DA - 2005/4// PY - 2005/4// DO - 10.1109/tc.2005.56 VL - 54 IS - 4 SP - 385-397 J2 - IEEE Trans. Comput. LA - en OP - SN - 0018-9340 UR - http://dx.doi.org/10.1109/tc.2005.56 DB - Crossref KW - Burrows Wheeler transform KW - data compression KW - source coding KW - suffix sorting KW - VLSI ER - TY - CHAP TI - Techniques and Applications of Capacitive Micromachined Ultrasonic Transducers AU - Ergun, A.S. AU - Yaralioglu, G.G. AU - Oralkan, Ö. AU - Khuri-Yakub, B.T. T2 - Fabrication Techniques for MEMS/NEMS A2 - Leondes, C.T. T3 - MEMS/NEMS Handbook PY - 2005/// VL - 2 SP - 223–280 PB - Springer ER - TY - CONF TI - Nitride-based two-terminal oscillators operating in the THz regime AU - Kim, K. W. AU - Sokolov, V. N. AU - Kochelap, V. A. AU - Korotyeyev, V. V. AU - Woolard, D. L. T2 - Defense and Security A2 - Hwu, R. Jennifer A2 - Woolard, Dwight L. A2 - Rosker, Mark J. AB - We present a theoretical study of two-terminal nitride-based oscillators utilizing two different hot-electron transport regimes determined by the interaction of the electrons with polar optical phonons, which are capable to generate current/voltage oscillations in the THz-frequency range. The first is the limited space-charge accumulation (LSA) regime based on the negative differential resistance (NDR) in a bulk-like GaN structure at room temperature at high electric field E > Et (Et ≈ 150 kV/cm). The second is the streaming regime in a quantum well (QW) structure in moderate electric field (1-10 kV/cm) at the nitrogen temperature or higher. The latter corresponds to the optical-phonon transit-time (OPTT) resonance and typically does not lead to an NDR at zero frequency. We show that for both regimes, real part of the electron dynamic mobility can be negative within certain THz-frequency windows, whose location and width depend on E. For a 100-nm n-GaN diode with a cross-section of 500 μm2 and the electron density of 1×1017 cm-3, the generated microwave power is estimated to be ≈ 0.6 W with the dc-to-rf conversion efficiency ≈ 9 % and the magnitude of the NDR of -1.3 Ω. When the streaming transport is realized in the QW channel, the generated power is estimated to be about 350 mW with the efficiency of few percent for a ten QWs GaN-based structure. Hence, the investigated transport mechanisms provide efficient mean to achieve very high-frequency microwave generation in the nitrides. C2 - 2005/5/18/ C3 - Terahertz for Military and Security Applications III DA - 2005/5/18/ DO - 10.1117/12.602975 PB - SPIE UR - http://dx.doi.org/10.1117/12.602975 DB - Crossref KW - group-III nitrides KW - hot electrons KW - dynamic high-frequency electron mobility KW - terahertz generation ER - TY - JOUR TI - High-speed and high-frequency electron effects in nitride semiconductors for terahertz applications AU - Kim, K. W. AU - Sokolov, V. N. AU - Kochelap, V. A. AU - Korotyeyev, V. V. AU - Woolard, D. L. T2 - physica status solidi (c) AB - We discuss the basic properties of the transient hot-electron transport and dynamic mobility in group-III nitrides under dominant electron–polar-optical-phonon scattering determining their capability for applications in THz frequency range. For bulk samples with high electron concentration, we provide the phase-plane analysis of the time-dependent transient transport and classification of different transient regimes depending on the initial conditions. The calculations predict a frequency interval with negative dynamic electron mobility where the amplification and generation of microwaves in THz frequency range is possible. For quantum-well heterostructures with low electron concentration under the streaming regime at moderate fields, we have revealed THz frequency windows of the negative microwave mobility, which enables the development of a tunable THz laser based on nitride quantum heterostructures. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) DA - 2005/5// PY - 2005/5// DO - 10.1002/pssc.200461372 VL - 2 IS - 7 SP - 2569-2572 J2 - phys. stat. sol. (c) LA - en OP - SN - 1610-1634 1610-1642 UR - http://dx.doi.org/10.1002/pssc.200461372 DB - Crossref ER - TY - JOUR TI - SiGe bipolar transceiver circuits operating at 60 GHz AU - Floyd, B.A. AU - Reynolds, S.K. AU - Pfeiffer, U.R. AU - Zwick, T. AU - Beukema, T. AU - Gaucher, B. T2 - IEEE Journal of Solid-State Circuits AB - A low-noise amplifier, direct-conversion quadrature mixer, power amplifier, and voltage-controlled oscillators have been implemented in a 0.12-/spl mu/m, 200-GHz f/sub T/290-GHz f/sub MAX/ SiGe bipolar technology for operation at 60 GHz. At 61.5 GHz, the two-stage LNA achieves 4.5-dB NF, 15-dB gain, consuming 6 mA from 1.8 V. This is the first known demonstration of a silicon LNA at V-band. The downconverter consists of a preamplifier, I/Q double-balanced mixers, a frequency tripler, and a quadrature generator, and is again the first known demonstration of silicon active mixers at V-band. At 60 GHz, the downconverter gain is 18.6 dB and the NF is 13.3 dB, and the circuit consumes 55 mA from 2.7 V, while the output buffers consume an additional 52 mA. The balanced class-AB PA provides 10.8-dB gain, +11.2-dBm 1-dB compression point, 4.3% maximum PAE, and 16-dBm saturated output power. Finally, fully differential Colpitts VCOs have been implemented at 22 and 67 GHz. The 67-GHz VCO has a phase noise better than -98 dBc/Hz at 1-MHz offset, and provides a 3.1% tuning range for 8-mA current consumption from a 3-V supply. DA - 2005/1// PY - 2005/1// DO - 10.1109/jssc.2004.837250 VL - 40 IS - 1 SP - 156-167 J2 - IEEE J. Solid-State Circuits OP - SN - 0018-9200 UR - http://dx.doi.org/10.1109/jssc.2004.837250 DB - Crossref KW - direct-conversion receiver KW - low-noise amplifier (LNA) KW - millimeter-wave bipolar integrated circuits KW - mixer KW - power amplifier KW - SiGe KW - V-band KW - voltage-controlled oscillator (VCO) KW - 60 GHz ER - TY - JOUR TI - WCDMA direct-conversion receiver front-end comparison in RF-CMOS and SiGe BiCMOS AU - Floyd, B.A. AU - Reynolds, S.K. AU - Zwick, T. AU - Khuon, L. AU - Beukema, T. AU - Pfeiffer, U.R. T2 - IEEE Transactions on Microwave Theory and Techniques AB - Wide-band code-division multiple-access direct-conversion receiver front-ends have been implemented in both 0.25-/spl mu/m RF-CMOS and SiGe BiCMOS technologies. These circuits have been designed for the same application, radio architecture, and system specifications, allowing relevant comparisons to be made. The front-ends include a bypassable low-noise amplifier, a quadrature downconverter, baseband variable-gain amplifiers, and a local-oscillator frequency divider with output buffers. At 24.5 mA of total current consumption from a 2.7-3.3-V supply, the CMOS front-end has a noise figure of 5.3 dB, in-band third-order intercept point (IIP3) and second-order intercept point (IIP2) of -14 and +20.7 dBm, respectively, and out-of-band IIP3 and IIP2 of >+1.2 and +69 dBm, respectively. Compared to an SiGe front-end consuming 22 mA, the CMOS circuit has a 2-dB higher noise figure, comparable out-of-band linearity, 3-dB higher in-band IIP3, 12-dB lower in-band IIP2, and 7-dB higher LO-to-RF leakage. DA - 2005/4// PY - 2005/4// DO - 10.1109/tmtt.2005.845742 VL - 53 IS - 4 SP - 1181-1188 J2 - IEEE Trans. Microwave Theory Techn. OP - SN - 0018-9480 UR - http://dx.doi.org/10.1109/tmtt.2005.845742 DB - Crossref KW - BiCMOS KW - direct-conversion receiver KW - low-noise amplifier (LNA) KW - local oscillator (LO) buffer KW - mixer KW - RF CMOS KW - SiGe KW - technology assessment KW - wide-band code-division multiple access (WCDMA) ER - TY - JOUR TI - On-Chip Antennas in Silicon ICs and Their Application AU - O, K.K. AU - Kim, K. AU - Floyd, B.A. AU - Mehta, J.L. AU - Yoon, H. AU - Hung, C.-M. AU - Bravo, D. AU - Dickson, T.O. AU - Guo, X. AU - Li, R. AU - Trichy, N. AU - Caserta, J. AU - Bomstad, W.R. AU - Branch, J. AU - Yang, D.-J. AU - Bohorquez, J. AU - Seok, E. AU - Gao, L. AU - Sugavanam, A. AU - Lin, J.-J. AU - Chen, J. AU - Brewer, J. T2 - IEEE Transactions on Electron Devices AB - The feasibility of integrating antennas and required circuits to form wireless interconnects in foundry digital CMOS technologies has been demonstrated. The key challenges including the effects of metal structures associated with integrated circuits, heat removal, packaging, and interaction between transmitted and received signals, and nearby circuits appear to be manageable. This technology can potentially be applied for implementation of a true single-chip radio for general purpose communication, on-chip and inter-chip data communication systems, RFID tags, RF sensors/radars, and others. DA - 2005/7// PY - 2005/7// DO - 10.1109/ted.2005.850668 VL - 52 IS - 7 SP - 1312-1323 J2 - IEEE Trans. Electron Devices LA - en OP - SN - 0018-9383 UR - http://dx.doi.org/10.1109/ted.2005.850668 DB - Crossref KW - BiCMOS KW - clock distribution KW - CMOS KW - data communication KW - on-chip antenna KW - silicon KW - wireless ER - TY - JOUR TI - 10+ gb/s 90-nm CMOS serial link demo in CBGA package AU - Rylov, S. AU - Reynolds, S. AU - Storaska, D. AU - Floyd, B. AU - Kapur, M. AU - Zwick, T. AU - Gowda, S. AU - Sorna, M. T2 - IEEE Journal of Solid-State Circuits AB - We report a 10+ Gb/s serial link demo chip with NRZ signaling in 90-nm CMOS. It consists of a full-rate 4:1 MUX with 8-tap feed-forward equalizer, a half-rate 1:4 DEMUX with programmable peaking pre-amplifier, and a parallel port interface. All coefficients of the 8-tap FIR filter have programmable polarity and magnitude. The chip is housed in CBGA package and has ESD protection devices on all pins. All clock signals are supplied externally. The measured maximum speeds of stand-alone transmitter and receiver are 11.7 Gb/s and 13.3 Gb/s, respectively, and maximum back-to-back operation speed (transmitter + receiver) is 11.4 Gb/s. The chip operates at 10 Gb/s over 20 ft of lossy cable with 20 dB attenuation at 5 GHz. All circuits in the chip use a single 1.0 V power supply, except TX output driver and RX input termination network, which use 1.4 V supply. Total power consumption of TX and RX from the two supplies is 280 mW. DA - 2005/9// PY - 2005/9// DO - 10.1109/jssc.2005.848177 VL - 40 IS - 9 SP - 1987-1991 J2 - IEEE J. Solid-State Circuits OP - SN - 0018-9200 UR - http://dx.doi.org/10.1109/jssc.2005.848177 DB - Crossref KW - CBGA package KW - channel equalization KW - CMOS KW - feedforward equalizer KW - high-speed serial links KW - receiver KW - transmitter ER - TY - JOUR TI - Design and Compliance Testing of a SiGe WCDMA Receiver IC With Integrated Analog Baseband AU - Reynolds, S.K. AU - Floyd, B.A. AU - Beukema, T.J. AU - Zwick, T. AU - Pfeiffer, U.R. T2 - Proceedings of the IEEE AB - A 2.7-3.3 V 32-mA SiGe direct-conversion wide-band code division multiple access (WCDMA) receiver IC integrating the RF front-end and analog baseband on a single chip has been completed and measured. Analog performance specifications for the design were driven by the 3GPP specifications. To close the loop from 3GPP specifications to IC design specifications to hardware performance results, a subset of compliance tests for both the analog as well as the digital 3GPP specifications was performed. The IC design includes a bypassable low-noise amplifier (LNA), a quadrature direct-downconverter, an automatically tuned channel-select filter, wide dynamic-range baseband amplifiers, and a serial digital interface. Power-saving modes allow the LNA to be powered down when the input signal is sufficiently large, reducing current consumption to 23 mA. In addition, the entire Q-channel signal path can be optionally powered down during control-channel monitoring, further reducing current draw to 17 mA nominal. The IC showed full compliance with the static channel 3GPP specification tests performed, including all analog/RF compliance tests and a set of DPCH/spl I.bar/Ec/Ior sensitivity tests from 12.2 through 384 kb/s as measured with a software baseband processor. DA - 2005/9// PY - 2005/9// DO - 10.1109/jproc.2005.852229 VL - 93 IS - 9 SP - 1624-1636 J2 - Proc. IEEE OP - SN - 0018-9219 UR - http://dx.doi.org/10.1109/jproc.2005.852229 DB - Crossref KW - BiCMOS KW - code division multiaccess KW - direct conversion KW - land mobile radio cellular systems KW - low-noise amplifiers (LNAs) KW - mixers KW - receivers KW - SiGe ER - TY - JOUR TI - Coherent array imaging using phased subarrays. Part II: simulations and experimental results AU - Johnson, J.A. AU - Oralkan, O. AU - Ergun, S. AU - Demirci, U. AU - Karaman, M. AU - Khuri-Yakub, B.T. T2 - IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control AB - The basic principles and theory of phased subarray (PSA) imaging imaging provides the flexibility of reducing the number of front-end hardware channels between that of classical synthetic aperture (CSA) imaging--which uses only one element per firing event--and full-phased array (FPA) imaging-which uses all elements for each firing. The performance of PSA generally ranges between that obtained by CSA and FPA using the same array, and depends on the amount of hardware complexity reduction. For the work described in this paper, we performed FPA, CSA, and PSA imaging of a resolution phantom using both simulated and experimental data from a 3-MHz, 3.2-cm, 128-element capacitive micromachined ultrasound transducer (CMUT) array. The simulated system point responses in the spatial and frequency domains are presented as a means of studying the effects of signal bandwidth, reconstruction filter size, and subsampling rate on the PSA system performance. The PSA and FPA sector-scanned images were reconstructed using the wideband experimental data with 80% fractional bandwidth, with seven 32-element subarrays used for PSA imaging. The measurements on the experimental sector images indicate that, at the transmit focal zone, the PSA method provides a 10% improvement in the 6-dB lateral resolution, and the axial point resolution of PSA imaging is identical to that of FPA imaging. The signal-to-noise ratio (SNR) of PSA image was 58.3 dB, 4.9 dB below that of the FPA image, and the contrast-to-noise ratio (CNR) is reduced by 10%. The simulated and experimental test results presented in this paper validate theoretical expectations and illustrate the flexibility of PSA imaging as a way to exchange SNR and frame rate for simplified front-end hardware. DA - 2005/1// PY - 2005/1// DO - 10.1109/tuffc.2005.1397350 VL - 52 IS - 1 SP - 51-64 J2 - IEEE Trans. Ultrason., Ferroelect., Freq. Contr. OP - SN - 0885-3010 UR - http://dx.doi.org/10.1109/tuffc.2005.1397350 DB - Crossref ER - TY - JOUR TI - Capacitive micromachined ultrasonic transducer design for high power transmission AU - Bayram, B. AU - Oralkan, O. AU - Ergun, A.S. AU - Haeggstrom, E. AU - Yaralioglu, G.G. AU - Khuri-Yakub, B.T. T2 - IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control AB - Capacitive micromachined ultrasonic transducers (cMUTs) were developed to meet the demands of the ultrasonic industry. To achieve maximum efficiency, the conventional operation of the cMUT requires a bias voltage close to the collapse voltage. Total acoustic output pressure is limited by the efficiency of the cMUT and the maximum-allowed pulse voltage on the membrane. In this paper, we propose the collapse-snapback operation of the cMUT: the membrane is collapsed onto the substrate in the collapsing cycle, and released in the snapback cycle. The collapse-snapback operation overcomes the above-mentioned limitations of the conventional operation. The collapse-snapback operation utilizes a larger range of membrane deflection profiles (both collapsed and released profiles) and generates higher acoustic output pressures. The static finite element calculations were performed to design cMUTs with specific collapse and snapback voltages by changing the electrode parameters (radius (re), position (de), and thickness (te)). These designs were refined for optimum average displacement per cycle. An electrode radius greater than 60% of the membrane radius significantly improved the displacement per volt. Moderately thick membranes (te approximately 0.2 microm) were preferred, as thicker membranes reduced the displacement per volt. Under proper bias conditions, the collapse-snapback operation, designed for high-power transmission, allowed the application of pulse voltages larger than the difference of collapse and snapback voltages. Dynamic finite element calculations of an infinite cMUT array on the substrate loaded with acoustic fluid medium were performed to determine the dynamic response of the cMUT. Commercially available FEM packages ANSYS and LS-DYNA were used for static and dynamic calculations, respectively. The cMUTs were fabricated for optimal performance in the collapse-snapback operation. The transmit experiments were performed on a 2-D cMUT array using a calibrated hydrophone. Taking into account the attenuation and diffraction losses, the pressure on the cMUT surface was extracted. The cMUT generated 0.47 MPa (6 kPa/V) and 1.04 MPa (11 kPa/V) in the conventional and collapse-snapback operations, respectively. Therefore, collapse-snapback operation of the cMUTs was superior for high-power transmission. DA - 2005/2// PY - 2005/2// DO - 10.1109/tuffc.2005.1406558 VL - 52 IS - 2 SP - 326-339 J2 - IEEE Trans. Ultrason., Ferroelect., Freq. Contr. OP - SN - 0885-3010 UR - http://dx.doi.org/10.1109/tuffc.2005.1406558 DB - Crossref ER - TY - JOUR TI - Capacitive micromachined ultrasonic transducers: fabrication technology AU - Erguri, A.S. AU - Huang, Yongli AU - Zhuang, Xuefeng AU - Oralkan, O. AU - Yarahoglu, G.G. AU - Khuri-Yakub, B.T. T2 - IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control AB - Capacitive micromachined ultrasonic transducer (cMUT) technology is a prime candidate for next generation imaging systems. Medical and underwater imaging and the nondestructive evaluation (NDE) societies have expressed growing interest in cMUTs over the years. Capacitive micromachined ultrasonic transducer technology is expected to make a strong impact on imaging technologies, especially volumetric imaging, and to appear in commercial products in the near future. This paper focuses on fabrication technologies for cMUTs and reviews and compares variations in the production processes. We have developed two main approaches to the fabrication of cMUTs: the sacrificial release process and the recently introduced wafer-bonding method. This paper gives a thorough review of the sacrificial release processes, and it describes the new wafer-bonding method in detail. Process variations are compared qualitatively and quantitatively whenever possible. Through these comparisons, it was concluded that wafer-bonded cMUT technology was superior in terms of process control, yield, and uniformity. Because the number of steps and consequent process time were reduced (from six-mask process to four-mask process), turn-around time was improved significantly. DA - 2005/12// PY - 2005/12// DO - 10.1109/tuffc.2005.1563267 VL - 52 IS - 12 SP - 2242-2258 J2 - IEEE Trans. Ultrason., Ferroelect., Freq. Contr. OP - SN - 0885-3010 UR - http://dx.doi.org/10.1109/tuffc.2005.1563267 DB - Crossref ER - TY - JOUR TI - Dynamic analysis of capacitive micromachined ultrasonic transducers AU - Bayram, B. AU - Yaralioglu, G.G. AU - Kupnik, M. AU - Ergun, A.S. AU - Oralkan, O. AU - Nikoozadeh, A. AU - Khuri-Yakub, B.T. T2 - IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control AB - Electrostatic transducers are usually operated under a DC bias below their collapse voltage. The same scheme has been adopted for capacitive micromachined ultrasonic transducers (cMUTs). DC bias deflects the cMUT membranes toward the substrate, so that their centers are free to move during both receive and transmit operations. In this paper, we present time-domain, finite element calculations for cMUTs using LS-DYNA, a commercially available finite element package. In addition to this DC bias mode, other new cMUT operations (collapse and collapse-snapback) have recently been demonstrated. Because cMUT membranes make contact with the substrate in these new operations, modeling of these cMUTs should include contact analysis. Our model was a cMUT transducer consisting of many hexagonal membranes; because it was symmetrical, we modeled only one-sixth of a hexagonal cell loaded with a fluid medium. The finite element results for both conventional and collapse modes were compared to measurements made by an optical interferometer; a good match was observed. Thus, the model is useful for designing cMUTs that operate in regimes where membranes make contact with the substrate. DA - 2005/12// PY - 2005/12// DO - 10.1109/tuffc.2005.1563269 VL - 52 IS - 12 SP - 2270-2275 J2 - IEEE Trans. Ultrason., Ferroelect., Freq. Contr. OP - SN - 0885-3010 UR - http://dx.doi.org/10.1109/tuffc.2005.1563269 DB - Crossref ER - TY - CONF TI - Evaluation of Mutual Trust during Matchmaking AU - Altunay, M. AU - Brown, D. AU - Byrd, G. AU - Dean, R.A. T2 - Fifth IEEE International Conference on Peer-to-Peer Computing (P2P'05) AB - The authors introduced a new service discovery and matchmaking architecture, layered on top of Globus MDS3, that integrates mutual trust evaluations into the matchmaking process. The architecture adopts a symmetric approach, and checks trust policies of both grid users and resources without requiring policy disclosures. This approach eliminates run-time security failures arising from incompatible user/resource pairs, seamlessly integrates user-side authorization tools with the matchmaking process, and protects naive grid users by allowing a security principal to define policies that control the list of discoverable resources. C2 - 2005/12/13/ C3 - Fifth IEEE International Conference on Peer-to-Peer Computing (P2P'05) DA - 2005/12/13/ DO - 10.1109/p2p.2005.9 VL - 2005 SP - 133-140 PB - IEEE SN - 0769523765 UR - http://dx.doi.org/10.1109/p2p.2005.9 DB - Crossref ER - TY - JOUR TI - A biotelemetric system for human ECG measurements AU - Engin, Mehmet AU - Yamaner, Yalçın AU - Engin, Erkan Zeki T2 - Measurement AB - The use of telemedicine capabilities to therapy chronically ill patients is becoming more and more clinically relevant and economically cost effective. This paper presents own designed a prototype telemedicine system which provides human electrocardiogram (ECG) signals transferring via a mobile phone. System also covers the management of electronic records of patient and access to databases on the hospital side. The parts of system include an ECG amplifier, a communicator for data transferring and automated software which can receive and monitor ECG data. DA - 2005/9// PY - 2005/9// DO - 10.1016/j.measurement.2005.04.001 VL - 38 IS - 2 SP - 148-153 J2 - Measurement LA - en OP - SN - 0263-2241 UR - http://dx.doi.org/10.1016/j.measurement.2005.04.001 DB - Crossref KW - ECG KW - telemedicine KW - biomedical electronics ER - TY - JOUR TI - Topological overview of hybrid electric and fuel cell vehicular power system architectures and configurations AU - Emadi, Ali AU - Rajashekara, Kaushik AU - Williamson, Sheldon S AU - Lukic, Srdjan M T2 - IEEE Transactions on Vehicular Technology DA - 2005/// PY - 2005/// VL - 54 IS - 3 SP - 763-770 ER - TY - JOUR TI - Guest Editorial Special Section on Hybrid Electric and Fuel Cell Vehicles AU - Emadi, Ali AU - Rajashekara, Kaushik T2 - IEEE Transactions on Vehicular Technology DA - 2005/// PY - 2005/// VL - 54 IS - 3 SP - 761-762 ER - TY - JOUR TI - Packet processing on a SIMD stream processor AU - Rai, Jathin S. AU - Lai, Yu-Kuen AU - Byrd, Gregory T. T2 - Network Processor Design AB - This chapter explores the application of stream architectures to packet processing tasks, IPv4 Forwarding and AES encryption in particular. Both applications were run on generic stream architecture (Imagine), and experiments were conducted to characterize the performance of both applications for different configurations of this architecture. For a system clock of 500 MHz, the throughput of the AES encryption in ECB mode varies from 2.02 Gb/s (96-block packets) to 0.8 Gb/s (8-block packets). The IPv4 Forwarding application, with a configuration of one Imagine with 8 clusters, delivered a worst-case performance of around 67 cycles per packet, for a packet trace constructed from the MAE-WEST routing table. Hence, the forwarding engine was able to support packet traffic coming at a rate of OC-48 assuming a clock frequency of 500 MHz. The LRF and memory bandwidth characteristics of the two packet processing applications confirm that they are at two different ends of the application spectrum, with one being memory-intensive and the other being computation intensive. The low SRF characteristics for the two packet processing applications, compared to the Depth media application, is due to the fact that the processing of the packets for both applications is done primarily in one kernel. This results in reduced trips to the SRF between kernels, decreasing the SRF bandwidth utilization. The packet processing applications have comparable metrics to that of media applications indicating that this architecture could be as useful for network applications as it is for media applications. DA - 2005/// PY - 2005/// DO - 10.1016/b978-012088476-6/50008-3 SP - 119-144 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84882762165&partnerID=MN8TOARS ER - TY - CONF TI - Wireless sensors in reverberant enclosures: Characterizing a new radio channel AU - Van’T Hof, J.P. AU - Stancil, D.D. AB - Wireless sensor networks operating inside aircraft wings, unmanned air vehicles (UAV's), small submarines and/or automobile engine compartments experience a radio channel that can be highly reverberant and is not yet thoroughly characterized. To obtain a better understanding of these spaces as radio communications environments, measurements in the enclosed space radio channel are performed and models are presented that describe the channel dispersion properties. Communications performance is evaluated using a signal excitation/analysis method using a variety of signaling techniques and in several different frequency bands. C2 - 2005/// C3 - IEEE Vehicular Technology Conference DA - 2005/// DO - 10.1109/VETECF.2005.1558404 VL - 3 SP - 1747-1750 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-49249128055&partnerID=MN8TOARS ER - TY - CONF TI - Waveform shaping for time reversal interference cancellation: A time domain approach AU - Moura, J.M.F. AU - Jin, Y. AU - Zhu, J.-G. AU - Jiang, Y. AU - Stancil, D. AU - Cepni, A. AU - Henty, B. C2 - 2005/// C3 - Conference Record - Asilomar Conference on Signals, Systems and Computers DA - 2005/// VL - 2005 SP - 665-669 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33847608422&partnerID=MN8TOARS ER - TY - CONF TI - Super-resolution focusing and nulling in rich multipath environments using time-reversal techniques AU - Stancil, D.D. AU - Cepni, A.G. AU - Henty, B.E. AU - Jiang, Y. AU - Jin, Y. AU - Zhu, J.-G. AU - Moura, J.M.F. C2 - 2005/// C3 - ICEAA 2005 - 9th International Conference on Electromagnetics in Advanced Applications and EESC 2005 - 11th European Electromagnetic Structures Conference DA - 2005/// SP - 299-302 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84875360823&partnerID=MN8TOARS ER - TY - CONF TI - Single antenna time reversal adaptive interference cancellation AU - Moura, J.M.F. AU - Jin, Y. AU - Stancil, D. AU - Zhu, J.-G. AU - Cepni, A. AU - Jiang, Y. AU - Henty, B. AB - This paper presents the time reversal adaptive interferer canceller (TRAIC), a novel algorithm that uses time reversal techniques to cancel the presence of interferers. TRAIC is developed for broadband signals and a single emitting antenna. Experimental tests in the electromagnetic domain show the viability and the power of TRAIC. C2 - 2005/// C3 - ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings DA - 2005/// DO - 10.1109/ICASSP.2005.1416210 VL - IV UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33646784021&partnerID=MN8TOARS ER - TY - CONF TI - Single antenna microwave nulling using time-reversal techniques AU - Cepni, A.G. AU - Stancil, D.D. AB - In this paper, we describe a single antenna microwave nulling technique that makes use of time-reversal concepts. The time-domain experiments have shown that by using single antenna and time-reversal technique, we can have focusing as well as nulling at any point in space. We have done experiments at 2.45 GHz in a cylindrical cavity environment. The degree of nulling (or focusing) depends on the multipath components in the channel as well as the bandwidth of the signal. The cavity provides a multipath rich-environment where we can show focusing and nulling by using a relatively small bandwidth compared to free space. C2 - 2005/// C3 - IEEE MTT-S International Microwave Symposium Digest DA - 2005/// DO - 10.1109/MWSYM.2005.1517050 VL - 2005 SP - 1723-1726 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33749258392&partnerID=MN8TOARS KW - time-reversal KW - microwave KW - nulling KW - cylindrical cavity ER - TY - CONF TI - Scalar network analysis of wireless channels using IEEE 802.11g transmissions AU - Hess, J.C. AU - Henty, B.E. AU - Stancil, D.D. AB - In this work we demonstrate the feasibility of scalar network analysis of wireless channels using an IEEE 802.11g waveform with a separate receiver. We explore the concept using a laboratory grade Orthogonal Frequency Division Multiplexing (OFDM) signal generator and spectrum analyzer. We also demonstrate the technique with field test equipment. All results are confirmed using a network analyzer. We find that utilizing field test equipment allows us to obtain valid channel responses and statistics. Keywords—channel characterization; scalar network analysis; IEEE 802.11g; OFDM. C2 - 2005/// C3 - IEEE Vehicular Technology Conference DA - 2005/// DO - 10.1109/VETECF.2005.1558943 VL - 4 SP - 2226-2229 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84931413101&partnerID=MN8TOARS ER - TY - JOUR TI - On the capacity limits of HVAC duct channel for high-speed internet access AU - Xhafa, A.E. AU - Tonguz, O.K. AU - Cepni, A.G. AU - Stancil, D.D. AU - Nikitin, P.V. AU - Brodtkorb, D. T2 - IEEE Transactions on Communications AB - In this paper, we report theoretical and experimental channel-capacity estimates of heating, ventilation, and air conditioning (HVAC) ducts based on multicarrier transmission that uses M-ary quadrature amplitude modulation and measured channel responses at the 2.4-GHz industrial, scientific, and medical band. It is shown theoretically that data rates in excess of 1 Gb/s are possible over distances up to 500 m in straight ducts in which reflections have been suppressed. Our experimental results also show that even in the case of more complex HVAC duct networks (i.e., HVAC duct networks that include bends, tees, etc.) data rates over 2 Gb/s are possible. Our estimations in this case are valid for distances of up to 22 m, which was the maximum distance of our experimental setup. These experimental results, measured with a large-scale testbed set up at Carnegie Mellon University, Pittsburgh, PA, albeit limited in terms of transmitter-receiver separation distance, provide further evidence on the potential of HVAC systems as an attractive solution for providing communications in indoor wireless networks. DA - 2005/// PY - 2005/// DO - 10.1109/TCOMM.2004.841949 VL - 53 IS - 2 SP - 335-342 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-15544367680&partnerID=MN8TOARS KW - heating, ventilation, and air conditioning (HVAC) systems for wireless transmission KW - indoor propagation KW - internet access KW - multicarrier transmission KW - orthogonal frequency-division multiplexing (OFDM) ER - TY - CONF TI - Mechanism of domain expansion in MAMMOS AU - Herget, P. AU - Schlesinger, T.E. AU - Stancil, D.D. C2 - 2005/// C3 - INTERMAG ASIA 2005: Digests of the IEEE International Magnetics Conference DA - 2005/// UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-28444479132&partnerID=MN8TOARS ER - TY - JOUR TI - Mechanism for domain expansion in MAMMOS AU - Herget, P. AU - Schesinger, T.E. AU - Stancil, D.D. T2 - IEEE Transactions on Magnetics AB - A magnetic amplifying magnetooptical system (MAMMOS) model was created which calculates the size of the expanded domains in the readout layer by computing the forces on the domain wall. Using the model, the ratio of nucleation coercivity to domain wall motion coercivity, H/sub c,n//H/sub c,m/, was found to be an important factor governing the final expanded domain size in MAMMOS. Simulation results indicated that H/sub c,n//H/sub c,m/>5 is needed for a good readout signal. Experiments measuring the nucleation coercivity in localized areas on a MAMMOS readout layer agree with the modeling results. In the experiments, a wafer was patterned with islands of magnetic material and the switching behavior was measured. For a MAMMOS film, the ratio of H/sub c,n//H/sub c,m/ was measured to be 13 on average in a 400 /spl mu/m/sup 2/ area. DA - 2005/// PY - 2005/// DO - 10.1109/TMAG.2005.854676 VL - 41 IS - 10 SP - 2860-2862 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-27744540998&partnerID=MN8TOARS KW - magnetic amplifying magnetooptical system KW - magnetic domain expansion KW - magnetooptic recording ER - TY - CONF TI - Improved wireless performance from mode scattering in ventilation ducts AU - Henty, B.E. AU - Stancil, D.D. AB - Ventilation ducts are a convenient infrastructure for distributing wireless signals indoors. Conventional and historical use of single conductor metal waveguides for transmission of communications signals has focused on careful excitation and control of mode content in the waveguide - something that is possibly infeasible or financially undesirable in a ventilation duct setting. With this in mind, we investigate the mode scattering effects present in a ventilation duct T-junction and note with some surprise that improvement in the performance of an IEEE 802.11g communication can result from this scattering. C2 - 2005/// C3 - IEEE Antennas and Propagation Society, AP-S International Symposium (Digest) DA - 2005/// DO - 10.1109/APS.2005.1552093 VL - 2 B SP - 638-641 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33846870557&partnerID=MN8TOARS ER - TY - CONF TI - Experimental results on target detection in cluttered medium using electromagnetic time-reversal techniques AU - Cepni, A.G. AU - Stancil, D.D. AU - Zhu, J.-G. AU - Jiang, Y. AB - We describe an experimental technique that can be used to improve the detection performance of a radar system in cluttered environments. The detection algorithm depends on time-reversal techniques. By using time-reversal, the response from cluttered medium is first nulled. When the target enters into the medium, the electromagnetic energy focuses around the target so that a stronger echo is obtained. The initial experimental results show that using time-reversal techniques, we can improve the signal-to-noise ratio of the return-echo due to the target compared to conventional change-detection radar. C2 - 2005/// C3 - IEEE Antennas and Propagation Society, AP-S International Symposium (Digest) DA - 2005/// DO - 10.1109/APS.2005.1552761 VL - 4 B SP - 139-142 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33846895479&partnerID=MN8TOARS ER - TY - CONF TI - Dispersion in the enclosed-space radio channel: Measurements and model AU - Van’t Hof, J.P. AU - Stancil, D.D. AB - Sensor and instrumentation networks operating inside aircraft wings, unmanned air vehicle (UAV) fuselage, small submarine craft and/or automobile engine compartments could be significantly enhanced or enabled by implementing radio communications within these spaces. However, these enclosures are highly reverberant, and radio channel dispersion has been shown to be considerable in an empty-enclosure configuration. In this work, further dispersion measurements incorporating environmentally realistic objects are presented. Results are introduced that allow the channel dispersion parameters to be represented by a single measured channel parameter, making. an important advance towards complete enclosed space channel dispersion predictions. C2 - 2005/// C3 - IEEE Antennas and Propagation Society, AP-S International Symposium (Digest) DA - 2005/// DO - 10.1109/APS.2005.1552477 VL - 3 B SP - 225-228 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33846900027&partnerID=MN8TOARS ER - TY - CONF TI - Characterizing dispersion in the enclosed-space radio channel using a composite mode model AU - Van’t Hof, J.P. AU - Stancil, D.D. AB - Wireless communications inside enclosed space environments (e.g. aircraft wings and fuselage, auto-mobile engine compartments, etc.) provides a unique opportunity for sensor networks and instrumentation systems native to these spaces to operate with improved reliability, flexibility and capabilities. Since these enclosed environments are typically surrounded by reflective boundaries (i.e. metallic walls), the enclosed-space radio channel is very dispersive and presents a significant challenge to radio communications. In this work, empirical dispersion measurements in representative enclosed space environments are made and a simple model which considers only the enclosure volume, surface area, conductivity and frequency of operation, is found to predict dispersion parameters in the enclosed space channel with good results. C2 - 2005/// C3 - 2005 IEEE/ACES International Conference on Wireless Communications and Applied Computational Electromagnetics DA - 2005/// DO - 10.1109/WCACEM.2005.1469710 VL - 2005 SP - 820-825 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33744994571&partnerID=MN8TOARS ER - TY - JOUR TI - Antenna radiation resistance in waveguide and in free-space AU - Nikitin, P.V. AU - Stancil, D.D. T2 - IEEE Transactions on Antennas and Propagation AB - In this paper, we discuss the connection between radiation resistance formulas for antenna in free-space and in rectangular waveguide. We demonstrate with the example of monopole antenna that a transformation between the angular direction in free-space and mode indices in waveguide makes the formulas for antenna radiation resistance in free-space and in rectangular waveguide equivalent to each other. DA - 2005/// PY - 2005/// DO - 10.1109/TAP.2005.848524 VL - 53 IS - 6 SP - 2126-2128 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-22444448668&partnerID=MN8TOARS KW - antenna input impedance KW - antenna theory KW - waveguide excitation ER - TY - CONF TI - A novel time reversal method for target detection in cluttered media AU - Zhu, J.-G. AU - Jiang, Y. AU - Stancil, D.D. AU - Moura, J. AB - A cluttered environment with highly scattering objects significantly enhances the difficulty for detecting targets using electromagnetic waves. Time reversal methods have been developed in acoustic wave propagation. It has been shown that the super resolution focusing effect in acoustic wave propagation can also be achieved electromagnetic wave propagation. We present a novel time reversal method that nullifies the scattering objects to allow automatic focusing of the propagated electromagnetic wave on a target that is to be detected. Numerical simulations using the FDTD method have been carried out. The results show that the method significantly enhances the dynamic range of target detection in a highly scattering environment and could substantially increase target detectability. C2 - 2005/// C3 - IEEE Antennas and Propagation Society, AP-S International Symposium (Digest) DA - 2005/// DO - 10.1109/APS.2005.1552760 VL - 4 B SP - 135-138 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33846902380&partnerID=MN8TOARS ER - TY - JOUR TI - A multi-hop mobile networking test-bed for telematics AU - Mangharam, R. AU - Meyers, J.J. AU - Rajkumar, R. AU - Stancil, D.D. AU - Parikh, J.S. AU - Krishnan, H. AU - Kellum, C. T2 - SAE Technical Papers AB - An onboard vehicle-to-vehicle multi-hop wireless networking system has been developed to test the realworld performance of telematics applications. The system targets emergency and safety messaging, traffic updates, audio/video streaming and commercial announcements. The test-bed includes a Differential GPS receiver, an IEEE 802.11a radio card modified to emulate the DSRC standard, a 1xRTT cellular-data connection, an onboard computer and audio-visual equipment. Vehicles exchange data directly or via intermediate vehicles using a multi-hop routing protocol. The focus of the test-bed is to (a) evaluate the feasibility of high-speed inter-vehicular networking, (b) characterize 5.8GHz signal propagation within a dynamic mobile ad hoc environment, and (c) develop routing protocols for highly mobile networks. The test-bed has been deployed across five vehicles and tested over 400 miles on the road. DA - 2005/// PY - 2005/// DO - 10.4271/2005-01-1484 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84877169488&partnerID=MN8TOARS ER - TY - CONF TI - "Chip-size" antennas for implantable sensors and smart dust AU - Basset, P. AU - Alfaro, F. AU - Novosel, D. AU - De La Plaza, A. AU - Stancil, D. AU - Fedder, G.K. AB - In this paper, we present the analysis, design and experimental results of /spl lambda//4-patch antennas operating at /spl sim/10 GHz. The ground plane has been adjusted to the patch area in order to drastically reduce the antenna size. Several geometries are presented, with HFSS simulation results. Impedance matching calculations for maximum power transfer between the antenna and the rectifying circuit is also presented. For a 4/spl times/5/spl times/1.6 mm/sup 3/ rectangular antenna fabricated on an RT/Duroid 5880 PCB, the measured maximum gain is 0.75 dB/sub i/ at 10.3 GHz. C2 - 2005/// C3 - Digest of Technical Papers - International Conference on Solid State Sensors and Actuators and Microsystems, TRANSDUCERS '05 DA - 2005/// DO - 10.1109/SENSOR.2005.1496453 VL - 1 SP - 457-460 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-27544452980&partnerID=MN8TOARS ER - TY - CONF TI - Microwave signal nulling using multiple antennas and time-reversal method AU - Cepni, A.G. AU - Stancil, D.D. AU - Jiang, Y. AU - Zhu, J. AB - In this paper, we describe a multiple antenna microwave nulling technique that makes use of time-reversal concepts. The time-domain simulations and frequency domain experiments have shown that by using multiple antennas and time-reversal technique, we can maximize (focusing) as well as minimize (nulling) RF energy at active or passive target points in the medium. We have done experiments between 4 to 6 GHz in a laboratory environment. The degree of nulling as well as focusing depends on the multipath components in the channel and the bandwidth of the waveform. Using a 2-GHz bandwidth waveform, we have experimentally shown high-resolution microwave nulling results in a 2-D plane. C2 - 2005/// C3 - IEEE Vehicular Technology Conference DA - 2005/// DO - 10.1109/VETECF.2005.1558131 VL - 2 SP - 1274-1278 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84931438332&partnerID=MN8TOARS ER - TY - CONF TI - Thread-level speculation on a CMP can be energy efficient AU - Renau, Jose AU - Strauss, Karin AU - Ceze, Luis AU - Liu, Wei AU - Sarangi, Smruti AU - Tuck, James AU - Torrellas, Josep AB - Chip Multiprocessors (CMP) with Thread-Level Speculation (TLS) have become the subject of intense research. However, TLS is suspected of being too energy inefficient to compete against conventional processors. In this paper, we refute this claim. To do so, we first identify the main sources of dynamic energy consumption in TLS. Then, we present simple energy-saving optimizations that cut the energy cost of TLS by over 60% on average with minimal performance impact. The resulting TLS CMP, populated with four 3-issue cores, speeds-up full SPECint 2000 codes by 1.27 on average, while keeping the fraction of the chip's energy consumption due to TLS to only 20%. Compared to a 6-issue superscalar at the same frequency, the TLS CMP is on average faster, while consuming only 85% of its total on-chip power. C2 - 2005/// C3 - Proceedings of the 19th annual international conference on Supercomputing DA - 2005/// DO - 10.1145/1088149.1088178 SP - 219-228 ER - TY - CONF TI - Tasking with Out-of-Order Spawn in TLS Chip Multiprocessors: Microarchitecture and Compilation AU - Renau, J. Tuck AU - J., Wei AU - L., Ceze AU - L., Strauss AU - K., AU - Torrellas, J. AB - Chip Multiprocessors (CMPs) are flexible, high-frequency platforms on which to support Thread-Level Speculation (TLS). However, for TLS to deliver on its promise, CMPs must exploit multiple sources of speculative task-level parallelism, including any nesting levels of both subroutines and loop iterations. Unfortunately, these environments are hard to support in decentralized CMP hardware: since tasks are spawned out-of-order and unpredictably, maintaining key TLS basics such as task ordering and efficient resource allocation is challenging.While the concept of out-of-order spawning is not new, this paper is the first to propose a set of microarchitectural mechanisms that, altogether, fundamentally enable fast TLS with out-of-order spawn in a CMP. Moreover, we develop a fully-automated TLS compiler for aggressive out-of-order spawn. With our mechanisms, a TLS CMP with four 4-issue cores achieves an average speedup of 1.30 for full SPECint 2000 applications; the corresponding speedup for in-order only spawn is 1.04. Overall, our mechanisms unlock the potential of TLS for the toughest applications. C2 - 2005/// C3 - ACM International Conference on Supercomputing DA - 2005/// DO - 10.1145/1088149.1088173 SP - 179-188 ER - TY - CONF TI - POSH: A profiler-enhanced TLS compiler that leverages program structure AU - Liu, Wei AU - Tuck, James AU - Ceze, Luis AU - Strauss, Karin AU - Renau, Jose AU - Torrellas, Josep C2 - 2005/// C3 - IBM Watson P= AC2 Conference DA - 2005/// SP - 83-92 ER - TY - JOUR TI - Adaptive information processing: an effective way to improve perceptron branch predictors AU - Gao, H. AU - Zhou, H. T2 - Journal of Instruction-level Parallelism DA - 2005/// PY - 2005/// VL - 7 SP - 1-10 ER - TY - JOUR TI - A case for fault tolerance and performance enhancement using chip multi-processors AU - Zhou, H. T2 - IEEE Computer Architecture Letters DA - 2005/// PY - 2005/// VL - 4 SP - 1-4 ER - TY - CONF TI - Electronic textiles today and potential for the future AU - Ghosh, T. K. AU - Dhawan, A. AU - Muth, J. C2 - 2005/// C3 - Proceedings of International Conference on Emerging Trends in Polymers and Textiles : 7th, 8th January 2005 DA - 2005/// PB - New Delhi ER - TY - RPRT TI - Integration of high resolution imagery in cost-effective assessment of land use practices influencing erosion and sediment yield AU - Khorram, S. AU - Nelson, S. A. C. AU - Cakir, H. AU - Hester, D. B. DA - 2005/// PY - 2005/// VL - 221 ER - TY - PAT TI - Interpolating sense amplifier circuits and methods of operating the same AU - Nishida, Y. AU - Liu, W. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Scintillation detector, system and method providing energy and position information AU - Schreiner, R. S. AU - White, J. A. AU - Mayhugh, M. R. AU - Mataranza, G. AU - Rozsa, C. M. AU - Herr, D. J. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Patterning methods and systems using reflected interference patterns AU - Herr, D. J. C. AU - Joy, D. C. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Electrical device including dielectric layer formed by direct patterning process AU - Gleason, K. K. AU - Ober, C. AU - Herr, D. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Method and apparatus for achieving secure password access AU - Kermani, B. G. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Fuzzy logic system with evolutionary variables rules AU - Kermani, B. G. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Dynamic partitioning of memory banks among multiple agents AU - Bays, L. E. AU - Fadavi-Ardekani, J. AU - Gutta, S. AU - Kermani, B. G. AU - Niescier, R. J. AU - Smith, G. L. AU - Soto, W. G. AU - Greenwood, D. K. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Array compositions for improved signal detection AU - Dickinson, T. A. AU - Meade, S. AU - Barnard, S. M. AU - Czarnik, A. W. AU - Bierle, J. AU - Kermani, B. G. AU - Chee, M. S. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Organic semiconductor device and method AU - Lian, K. K. AU - Croswell, R. T. AU - Tungare, A. AU - Eliacin, M. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Solid-state DC circuit breaker AU - Huang, Q. AU - Zhou, X. AU - Xu, Z. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Emitter turn-off thyristors (ETO) AU - Huang, A. Q. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - CONF TI - Virtual multiprocessor: An analyzable, high-performance microarchitecture for real-time computing AU - El-Haj-Mahmoud, A. AU - Al-Zawawi, A. S. AU - Anantaraman, A. AU - Rotenberg, E. AB - The design of a real-time architecture is governed by a trade-off between analyzability necessary for real-time formalism and performance demanded by high-end embedded systems. We reconcile this trade-off with a novel Real-time Virtual Multiprocessor (RVMP). RVMP virtualizes a single in-order superscalar processor into multiple interference-free different-sized virtual processors. This provides a flexible spatial dimension. In the time dimension, the number and size of virtual processors can be rapidly reconfigured. A simple real-time scheduling approach concentrates scheduling within a small time interval, producing a simple repeating space/time schedule that orchestrates virtualization. RVMP successfully combines the analyzability (hence real-time formalism) of multiple processors with the flexibility (hence high performance) of simultaneous multithreading (SMT).Worst-case schedulability experiments show that more task-sets are provably schedulable on RVMP than on conventional rigid multiprocessors with equal aggregate resources, and the advantage only intensifies with more demanding task-sets. Run-time experiments show RVMP's statically-controlled coarser-grain space/time configurability is as effective as unsafe SMT. Moreover, RVMP provides a real-time formalism that SMT does not currently provide. C2 - 2005/// C3 - CASES 2005: International Conference on Compilers, Architecture, and Synthesis for Embedded Systems, September 24-27, 2005, San Francisco, California, USA DA - 2005/// DO - 10.1145/1086297.1086326 SP - 213-224 PB - New York: ACM Press SN - 159593149X ER - TY - JOUR TI - Tapping ZettaRAM (TM) for low-power memory systems AU - Venkatesan, RK AU - Al-Zawawi, AS AU - Rotenberg, E T2 - 11TH INTERNATIONAL SYMPOSIUM ON HIGH-PERFORMANCE COMPUTER ARCHITECTURE, PROCEEDINGS AB - ZettaRAM/spl trade/ is a new memory technology under development by ZettaCore/spl trade/ as a potential replacement for conventional DRAM. The key innovation is replacing the conventional capacitor in each DRAM cell with "charge-storage" molecules - a molecular capacitor. We look beyond ZettaRAM's manufacturing benefits, and approach it from an architectural viewpoint to discover benefits within the domain of architectural metrics. The molecular capacitor is unusual because the amount of charge deposited (critical for reliable sensing) is independent of write voltage, i.e., there is a discrete threshold voltage above/below which the device is fully charged/discharged. Decoupling charge from voltage enables manipulation via arbitrarily small bitline swings, saving energy. However, while charge is voltage-independent, speed is voltage-dependent. Operating too close to the threshold causes molecules to overtake peripheral circuitry as the overall performance limiter. Nonetheless, ZettaRAM offers a speed/energy trade-off whereas DRAM is inflexible, introducing new dimensions for architectural management of memory. We apply architectural insights to tap the full extent of ZettaRAM's power savings without compromising performance. Several factors converge nicely to direct focus on L2 writebacks: (i) they account for 80% of row buffer misses in the main memory, thus most of the energy savings potential, and (ii) they do not directly stall the processor and thereby offer scheduling flexibility for tolerating extended molecule latency. Accordingly, slow writes (low energy) are applied to non-critical writebacks and fast writes (high energy) to critical fetches. The hybrid write policy is combined with two options for tolerating delayed writebacks: large buffers with access reordering or L2-cache eager writebacks. Eager writebacks are remarkably synergistic with ZettaRAM: initiating writebacks early in the L2 cache compensates for delaying them at the memory controller. Dual-speed writes coupled with eager writebacks yields energy savings of 34% (out of 41% with uniformly slow writes), with less than 1% performance degradation. DA - 2005/// PY - 2005/// DO - 10.1109/hpca.2005.35 SP - 83-94 SN - 1530-0897 ER - TY - CHAP TI - Trace caches AU - Rotenberg, E. T2 - Speculative execution in high performance computer architectures A2 - Kaeli, D. A2 - Yew, P.-C. PY - 2005/// DO - 10.1201/9781420035155.ch4 PB - Boca Raton, FL: Chapman & Hall/CRC SN - 1584884479 ER - TY - CHAP TI - Architecture of embedded microprocessors AU - Rotenberg, E. AU - Anantaraman, A. T2 - Multiprocessor systems on chips A2 - Wolf, W. A2 - Jerraya, A. AB - This chapter focuses on the architecture of microprocessor units (MPUs) used in systems-on-chips (SoCs) and embedded systems. It reviews the reasons for the parallel evolution of embedded and desktop processors and reasons for dual tracks targeting open versus closed embedded systems—these systems constrain microarchitectural evolution due to the need for timing predictability. The chapter also describes the recent research aimed at bridging the dual tracks. SoC designs are powered by one or more general-purpose MPUs, digital signal processors (DSPs), and fixed-function coprocessors. Embedded processors are general purpose in a different sense than the high–performance processors used in personal computers. A personal computer is expected to run arbitrary software—productivity tools, computer-aided design (CAD), games, multimedia, and the operating systems (OS). In contrast, a closed embedded system runs a fixed set of tasks or task-set. The difference between embedded and high–performance processors lies in their stages of evolution. Contemporary embedded processors lag some 10 years behind their high–performance counterparts in terms of complexity. Whereas high–performance processor designs push and exceed the limits of technology, minimal embedded processor designs fully exploit the power and cost scaling advantages of new generations of CMOS technology. PY - 2005/// DO - 10.1016/b978-012385251-9/50018-9 SP - 81-112 PB - San Francisco, CA: Morgan Kaufmann; Oxford: Elsevier Science SN - 012385251X ER - TY - PAT TI - High/low work function metal alloys for integrated circuit electrodes AU - Misra, V. AU - Zhong, H. AU - Hong, S. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Variable-persistence molecular memory devices and methods of operation thereof AU - Rotenberg, E. AU - Lindsey, J. S. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Supermolecular structureS and devices made from same AU - Herr, D. J. C. AU - Zhirnov, V. V. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Optoelectronic devices having arrays of quantum-dot compound semiconductor superlattices therein AU - Zhang, Z. AU - Misra, V. AU - Bedair, S. M. A. AU - Ozturk, M. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Methods, systems, and associated implantable devices for radiation dose verification for therapies used to treat tumors AU - Scarantino, C. W. AU - Nagle, H. T. AU - Hall, L. C. AU - Mueller, J. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Methods, systems, and associated implantable devices for dynamic monitoring of physiological and biological properties of tumors AU - Scarantino, C. W. AU - Nagle, H. T. AU - Hall, L. C. AU - Mueller, J. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Methods of fabricating crossbar array microelectronic electrochemical cells C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Hybrid molecular memory devices and methods of use thereof AU - Misra, V. AU - Gowda, S. AU - Mathur, G. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - JOUR TI - Network access control for mobile ad-hoc networks AU - Wang, P. AU - Ning, P. AU - Reeves, D. S. T2 - Information and Communications Security DA - 2005/// PY - 2005/// VL - 3783 SP - 350-362 ER - TY - CHAP TI - Low-overhead core swapping for thermal management AU - Kursun, E. AU - Reinman, G. AU - Sair, S. AU - Shayesteh, A. AU - Sherwood, T. T2 - Power-aware computer systems: 4th International Workshop, PACS 2004, Portland, OR, USA, December 5, 2004 (Lecture notes in computer science; 3471) A2 - B. Falsafi, T.N. Vijaykumar CN - TK7895.P68 P33 2004 PY - 2005/// VL - 3471 SP - 46-60 PB - Berlin: Springer ER - TY - JOUR TI - The asymptotic capacity of multiple-antenna Rayleigh-fading channels AU - Kamath, MA AU - Hughes, BL T2 - IEEE TRANSACTIONS ON INFORMATION THEORY AB - We consider the asymptotic behavior of the capacity of multiple-antenna Rayleigh-fading channels in the limit as the transmit and receive arrays become large. We show that the capacity converges in distribution to a Gaussian random variable, and give closed-form formulas for its mean and variance. These results enable us to derive the first asymptotic formula for outage rates, as well as a sharper estimate of the error in previously reported asymptotic formulas for ergodic capacity. Although these formulas are asymptotic, we show by simulation that they are often quite accurate, even for relatively small arrays. DA - 2005/12// PY - 2005/12// DO - 10.1109/tit.2005.858966 VL - 51 IS - 12 SP - 4325-4333 SN - 1557-9654 KW - capacity KW - fading channels KW - multiple-antenna communication KW - random matrix theory KW - space-time coding ER - TY - JOUR TI - Enhanced photoconductivity of ZnO films Co-doped with nitrogen and tellurium AU - Porter, H. L. AU - Cai, A. L. AU - Muth, J. F. AU - Narayan, J. T2 - Applied Physics Letters AB - Zinc oxide films are typically found to be n type, and conductive under most growth conditions and growth methods. Co-doping with multiple elements is one strategy for improving the electrical and optical properties of zinc oxide materials for optoelectronic device applications. Using pulsed-laser deposition, thin ZnO films were grown on c-axis oriented sapphire. The films were co-doped with nitrogen and tellurium. Depending on the relative concentrations of the dopants, the resistivity of the films was observed to increase by several orders of magnitude, significantly improving the photoconductive response. The enhancement of the photosensitivity reached a maximum at a tellurium concentration of around 1020cm−3. DA - 2005/5/23/ PY - 2005/5/23/ DO - 10.1063/1.1923194 VL - 86 IS - 21 SP - 211918 J2 - Appl. Phys. Lett. LA - en OP - SN - 0003-6951 1077-3118 UR - http://dx.doi.org/10.1063/1.1923194 DB - Crossref ER - TY - JOUR TI - Eliminating conflict misses using prime number-based cache indexing AU - Kharbutli, M AU - Solihin, Y AU - Lee, J T2 - IEEE TRANSACTIONS ON COMPUTERS AB - Using alternative cache indexing/hashing functions is a popular technique to reduce conflict misses by achieving a more uniform cache access distribution across the sets in the cache. Although various alternative hashing functions have been demonstrated to eliminate the worst-case conflict behavior, no study has really analyzed the pathological behavior of such hashing functions that often results in performance slowdown. We present an in-depth analysis of the pathological behavior of cache hashing functions. Based on the analysis, we propose two new hashing functions, prime modulo and odd-multiplier displacement, that are resistant to pathological behavior and yet are able to eliminate the worst-case conflict behavior in the L2 cache. We show that these two schemes can be implemented in fast hardware using a set of narrow addition operations, with negligible fragmentation in the L2 cache. We evaluate the schemes on 23 memory intensive applications. For applications that have nonuniform cache accesses, both prime modulo and odd-multiplier displacement hashing achieve an average speedup of 1.27 compared to traditional hashing, without slowing down any of the 23 benchmarks. We also evaluate using odd-multiplier displacement function with multiple multipliers in conjunction with a skewed associative L2 cache. The skewed associative cache achieves a better average speedup at the cost of some pathological behavior that slows down four applications by up to 7 percent. DA - 2005/5// PY - 2005/5// DO - 10.1109/TC.2005.79 VL - 54 IS - 5 SP - 573-586 SN - 1557-9956 KW - cache hashing KW - cache indexing KW - prime modulo KW - odd-multiplier displacement KW - conflict misses ER - TY - JOUR TI - Electron-phonon interaction via the Pekar mechanism in nanostructures AU - Glavin, B. A. AU - Kochelap, V. A. AU - Linnik, T. L. AU - Kim, K. W. T2 - Physical Review B AB - We consider an electron-acoustic-phonon coupling mechanism associated with the dependence of crystal dielectric permittivity on the strain (the so-called Pekar mechanism) in nanostructures characterized by strong confining electric fields. The efficiency of Pekar coupling is a function of both the absolute value and the spatial distribution of the electric field. It is demonstrated that this mechanism exhibits a phonon wave-vector dependence similar to that of piezoelectricity and must be taken into account for electron transport calculations in nanostructures with extended field distributions. In particular, we analyze the role of Pekar coupling in energy relaxation in silicon inversion layers. Comparison with the recent experimental results is provided to illustrate its potential significance. DA - 2005/2/15/ PY - 2005/2/15/ DO - 10.1103/physrevb.71.081305 VL - 71 IS - 8 SP - J2 - Phys. Rev. B LA - en OP - SN - 1098-0121 1550-235X UR - http://dx.doi.org/10.1103/PhysRevB.71.081305 DB - Crossref ER - TY - JOUR TI - Effect of doping on the magnetic properties of GaMnN: Fermi level engineering AU - Reed, MJ AU - Arkun, FE AU - Berkman, EA AU - Elmasry, NA AU - Zavada, J AU - Luen, MO AU - Reed, ML AU - Bedair, SM T2 - APPLIED PHYSICS LETTERS AB - GaMnN dilute magnetic semiconductor samples, prepared by metalorganic chemical vapor deposition, are shown to exhibit ferromagnetism or even paramagnetism depending upon the type and concentration of extrinsic impurity present in the film. In addition, GaMnN deposited using growth parameters normally yielding a nonferromagnetic film becomes strongly ferromagnetic with the addition of magnesium, an acceptor dopant. Based upon these observations, it seems that ferromagnetism in this material system depends on the relative position of the Mn energy band and the Fermi level within the GaMnN band gap. Only when the Fermi level closely coincides with the Mn-energy level is ferromagnetism achieved. By actively engineering the Fermi energy to be within or near the Mn energy band, room temperature ferromagnetism is realized. DA - 2005/3/7/ PY - 2005/3/7/ DO - 10.1063/1.1881786 VL - 86 IS - 10 SP - SN - 1077-3118 ER - TY - JOUR TI - Autonomous coordination of aircraft formations using direct and nearest-neighbor approaches AU - Silverberg, L AU - Levedahl, BA T2 - JOURNAL OF AIRCRAFT AB - Two approaches are developed for autonomous coordination of aircraft formations. The development of the approaches relies on past work in the areas of distributed control (modal, robust, optimal, and decentralized). The formation coordination problem is divided into a tracking problem (changing the formation) and a regulation problem (maintaining the formation). How to separate the spatial parts of the tracking problem from the temporal parts is demonstrated. With respect to the regulation problem, it is shown that the goal of the regulation problem is to dampen uniformly the motion of the aircraft. It is pointed out that for fuel-optimality the closed-loop damping factors of the aircraft need to be less than π/2. Two types of decentralized coordination are examined: direct coordination (using inertial measurements) and nearest-neighbor coordination (using relative measurements). A perturbation analysis is developed for the efficient calculation of control gains that minimize power and uniformly dampen motion. A numerical example illustrates robust formation changes from nine-aircraft (3 × × 3) grids to V-type formations. Why the performance of direct coordination is generally better than the performance of nearestneighbor coordination and why implementing direct coordination is simpler than implementing nearest-neighbor coordination are explained. However, nearest-neighbor coordination can be used in collision avoidance, and so it must still be considered as a viable option. DA - 2005/// PY - 2005/// DO - 10.2514/1.6868 VL - 42 IS - 2 SP - 469-477 SN - 1533-3868 ER - TY - JOUR TI - A new and improved physics-based model for MOS transistors AU - Hauser, , JR T2 - IEEE TRANSACTIONS ON ELECTRON DEVICES AB - An improved MOS device model is derived based upon a first-order model for the dependency of MOS surface mobility on surface field and lateral drain field. A comparison with experimental data shows that a consistent set of physical parameters can be used to describe both long-channel nMOS devices and short-channel devices. The model can form the basis for improved compact MOS models for circuit analysis. DA - 2005/12// PY - 2005/12// DO - 10.1109/ted.2005.859623 VL - 52 IS - 12 SP - 2640-2647 SN - 1557-9646 KW - field-effect transistors (FETs) KW - MOSFETs KW - modeling KW - MIS devices KW - semiconductor device modeling ER - TY - JOUR TI - A multiscale approach to pixel-level image fusion AU - Ben Hamza, A. AU - He, Y. AU - Krim, H. AU - Willsky, A. T2 - Integrated Computer-aided Engineering AB - Pixel level image fusion refers to the processing and synergistic combination of information gathered by various imaging sources to provide a better understanding of a scene. We formulate the image fusion as an optimization problem and propose an inf DA - 2005/// PY - 2005/// DO - 10.3233/ica-2005-12201 VL - 12 IS - 2 SP - 135-146 ER - TY - JOUR TI - Surf zone entrainment, along-shore transport, and human health implications of pollution from tidal outlets AU - Grant, S. B. AU - Kim, J. H. AU - Jones, B. H. AU - Jenkins, S. A. AU - Wasyl, J. AU - Cudaback, C. T2 - Journal of Geophysical Research. Oceans DA - 2005/// PY - 2005/// VL - 110 IS - C10 ER - TY - JOUR TI - Parallel-coupled line filters with enhanced stopband performances AU - Fathelbab, WM AU - Steer, MB T2 - IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES AB - A new class of parallel-coupled line filters with broad stopband response is introduced. The design is based on the synthesis of bandpass prototypes with pre-defined upper stopband characteristics. The new filters have uniform- and stepped-impedance resonators, some of which are loaded by open-circuited stubs at their open-circuited ends. A seventh-order filter implementation is presented with a fundamental passband centered at 1 GHz. The measured wide-band transmission characteristic of the filter demonstrated a broad upper stopband and was in agreement with simulations. The performance of the new filter is also compared with the characteristic of a conventionally designed filter to highlight the advantages of the proposed design method. DA - 2005/12// PY - 2005/12// DO - 10.1109/TMTT.2005.859871 VL - 53 IS - 12 SP - 3774-3781 SN - 1557-9670 KW - capacitively loaded resonators KW - high-pass/bandpass filter prototypes KW - parallel-coupled line (PCL) filters KW - spurious stopband rejection KW - uniform/stepped-impedance resonators ER - TY - JOUR TI - Olanzapine versus risperidone in newly admitted acutely ill psychotic patients AU - Kraus, JE AU - Sheitman, BB AU - Cook, A AU - Reviere, R AU - Lieberman, JA T2 - JOURNAL OF CLINICAL PSYCHIATRY AB - Risperidone and olanzapine are the 2 most widely prescribed second-generation anti-psychotics. The purpose of this study was to compare the efficacy of risperidone and olanzapine using duration of hospitalization as the primary outcome measure. This outcome was selected as it is an indirect measure of how well patients are responding to the medication and represents a "real world" endpoint relevant to practicing hospital psychiatrists.The study was done at a large state psychiatric hospital in North Carolina from 2001 to 2003. Subjects were eligible for inclusion if they required treatment with an antipsychotic (e.g., positive symptoms) and were able to provide informed consent. Eighty-five patients entered the study and were randomly assigned to risperidone (N = 40) or olanzapine (N = 45) as their initial antipsychotic. Treatment was naturalistic, and dosing was based on the discretion of the treating physician.There was no significant difference in the mean durations of hospitalization for the risperidone group (7.9 days) as compared to the olanzapine group (8.1 days). There were no significant differences in the demographics of either treatment group, but, during the study, risperidone-treated patients used more antihistamines (chi(2) = 4.0, p = .05). Eighty percent of each group (N = 36, olanzapine; N = 32, risperidone) remained on the study medication at discharge.Risperidone and olanzapine were equally efficacious, suggesting that measures other than "efficacy" (e.g., side effects, cost) should be considered when determining overall "effectiveness" of treatment. DA - 2005/12// PY - 2005/12// DO - 10.4088/JCP.v66n1211 VL - 66 IS - 12 SP - 1564-1568 SN - 1555-2101 ER - TY - JOUR TI - Gallium nitride surface quantum wells AU - Muth, J. F. AU - Zhang, X. AU - Cai, A. AU - Fothergill, D. AU - Roberts, J. C. AU - Rajagopal, P. AU - Cook, J. W., Jr. AU - Piner, E. L. AU - Linthicum, K. J. T2 - Applied Physics Letters AB - Surface quantum-well emission has been observed from GaN-capped AlGaN∕GaN heterostructures grown by metalorganic chemical vapor deposition. The GaN cap, which forms the surface quantum well, is confined on one side by the vacuum level and on the other side by the AlGaN barrier layer. Photoluminescence at room temperature and cathodoluminescence studies show a strong emission peak corresponding to the lowest bound state of the surface quantum well and a correlation was made to the shift in surface quantum-well emission energy and the thickness of the GaN capping layer, which was varied from ∼15to40Å. The efficient surface quantum-well emission is indicative of low surface recombination velocities even without any surface passivation. DA - 2005/11/7/ PY - 2005/11/7/ DO - 10.1063/1.2123396 VL - 87 IS - 19 SP - 192117 J2 - Appl. Phys. Lett. LA - en OP - SN - 0003-6951 1077-3118 UR - http://dx.doi.org/10.1063/1.2123396 DB - Crossref ER - TY - JOUR TI - Effect of carrier blocking layers on the emission characteristics of AlGaN-based ultraviolet light emitting diodes AU - Park, JS AU - Fothergill, DW AU - Zhang, XY AU - Reitmeier, ZJ AU - Muth, JF AU - Davis, RF T2 - JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS AB - AlGaN-based thin film heterostructures suitable for ultraviolet light emitting diodes have been grown and fabricated into working devices with and without p-type and n-type AlGaN carrier-blocking layers at the top and the bottom of the quantum wells, respectively. The principal emission from each device occurred at 353 nm. The highest intensities of this peak were measured at all values of the injection current in the device with a p-type carrier-blocking layer at the top of the quantum well; this device also exhibited the highest values of light output power. Growth of an n-type carrier-blocking layer at the bottom of the quantum wells had an adverse effect on the light emitting diode characteristics. A broad peak centered at ∼540 nm exhibited yellow luminescence and was present in the spectra acquired from all the devices. This peak is attributed to absorption of the UV emission by and re-emission from the p-GaN and/or to the luminescence from the AlGaN within quantum wells by current injection. The intensity of this peak increased and saturated by the same order of magnitude as the intensity of the UV emission at 353 nm. DA - 2005/10// PY - 2005/10// DO - 10.1143/jjap.44.7254 VL - 44 IS - 10 SP - 7254-7259 SN - 0021-4922 KW - light emitting diode KW - ultraviolet KW - AlGaN KW - carrier blocking layer KW - quantum well ER - TY - JOUR TI - Characterization of remote inductively coupled CH4-N-2 plasma for carbon nitride thin-film deposition AU - Seo, H. AU - Kim, J. H. AU - Chung, K. H. AU - Kim, J. Y. AU - Kim, S. H. AU - Jeon, H. T2 - Journal of Applied Physics DA - 2005/// PY - 2005/// VL - 98 IS - 4 ER - TY - JOUR TI - A survey of cross-layer performance enhancements for Mobile IP networks AU - McNair, J AU - Tugcu, T AU - Wang, WY AU - Xie, JL T2 - COMPUTER NETWORKS AB - Among the characteristics of future wireless networks is the desire to support a wide range of wireless users and a diverse set of services from many different types of networks. One of the most often referenced networking protocols for diverse wireless and mobile networking is Mobile IP. Although recent focus has been on developing a micro-mobility architecture for Mobile IP, an emerging need is to enhance the unifying performance of Mobile IP by using a cross-layer, cross-technology, approach to protocol design, in order to serve a wide variety of users, services and networks. This paper provides a survey of recently proposed performance enhancements for Mobile IP and discusses the impact on network-level performance. After a review of the Mobile IP architecture, recent research on reducing handoff latency is discussed, including the use of layer 2 hints. Then, location registration is explored, including new techniques for authentication of mobile users. Finally, an overview of performance analysis models is provided to show the most recent approaches to determining the impact of mobility on a given network. DA - 2005/10/5/ PY - 2005/10/5/ DO - 10.1016/j.comnet.2005.06.001 VL - 49 IS - 2 SP - 119-146 SN - 1872-7069 KW - mobile IP KW - mobility KW - authentication KW - handoff ER - TY - JOUR TI - Work function tuning of nickel silicide by co-sputtering nickel and silicon AU - Biswas, N AU - Gurganus, J AU - Misra, V T2 - APPLIED PHYSICS LETTERS AB - Co-sputtered nickel silicide films were evaluated on thin layers of SiO2 gate dielectrics. Work function values ranging from 4.86eV for Ni rich films to 4.3eV were observed at 400°C and were found to be a strong function of the Ni and Si ratio in the films. Phase analysis indicated the presence of different phases of NixSiy for varying concentrations of Ni and Si. High-temperature characteristics, leakage, and change in equivalent oxide thickness values were also evaluated for selected conditions. Rutherford backscattering, x-ray diffraction, Auger electron spectroscopy and high-resolution transmission electron microscopy were used for material analyses. DA - 2005/10/24/ PY - 2005/10/24/ DO - 10.1063/1.2115072 VL - 87 IS - 17 SP - SN - 1077-3118 ER - TY - JOUR TI - Trust-Based Secure Workflow Path Construction AU - Altunay, M. AU - Brown, D. AU - Byrd, G. AU - Dean, R. T2 - Service-Oriented Computing – ICSOC 2007 AB - Security and trust relationships between services significantly govern their willingness to collaborate and participate in a workflow. Existing workflow tools do not consider such relationships as an integral part of their planning logic: rather, they approach security as a run-time issue. We present a workflow management framework that fully integrates trust and security into the workflow planning logic. It considers not only trust relationships between the workflow requestor and individual services, but also trust relationships among the services themselves. It allows each service owner to define an upper layer of collaboration policies (rules that specify the terms under which participation in a workflow is allowed) and integrates them into the planning logic. Services that are unfit for collaboration due to security violations are replaced at the planning stage. This approach increases the services owners’ control over the workflow path, their willingness for collaboration, and avoids run-time security failures. CN - [Electronic Resource] DA - 2005/// PY - 2005/// DO - 10.1007/11596141_29 VL - 3826 SP - 382-395 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33744965347&partnerID=MN8TOARS ER - TY - JOUR TI - Mini-special issue on Asia-Pacific Microwave Conference - Guest editorial AU - Steer, MB T2 - IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES DA - 2005/9// PY - 2005/9// DO - 10.1109/TMTT.2005.854222 VL - 53 IS - 9 SP - 2649-2649 SN - 0018-9480 ER - TY - JOUR TI - Investigation of work function tuning using multiple layer metal gate electrodes stacks for complementary metal-oxide-semiconductor applications AU - Jha, R AU - Lee, J AU - Majhi, P AU - Misra, V T2 - APPLIED PHYSICS LETTERS AB - Metal gate electrodes consisting of three layered stacks of metals are investigated for complementary metal-oxide-semiconductor device applications. It was observed that the effective work function of the entire gate electrode stack was dominated by the work function of the first metal layer (50Å of tantalum nitride) contacting the gate dielectric. No significant difference in the effective oxide thickness was observed in devices with and without the initial tantalum nitride layer. The potential reasons for this, based on the penetration of an electron wave function from the gate electrode to the gate dielectric and gate depletion due to longer Debye length of electrons in tantalum nitride, will be discussed. DA - 2005/11/28/ PY - 2005/11/28/ DO - 10.1063/1.2136425 VL - 87 IS - 22 SP - SN - 1077-3118 ER - TY - JOUR TI - Identification of a discrete planar symmetric shape from a single noisy view AU - Poliannikov, OV AU - Krim, H T2 - IEEE TRANSACTIONS ON IMAGE PROCESSING AB - In this paper, we propose a method for identifying a discrete planar symmetric shape from an arbitrary viewpoint. Our algorithm is based on a newly proposed notion of a view's skeleton. We show that this concept yields projective invariants which facilitate the identification procedure. It is, furthermore, shown that the proposed method may be extended to the case of noisy data to yield an optimal estimate of a shape in question. Substantiating examples are provided. DA - 2005/12// PY - 2005/12// DO - 10.1109/TIP.2005.859387 VL - 14 IS - 12 SP - 2051-2059 SN - 1057-7149 ER - TY - JOUR TI - High-performance and low-cost dual-thread VLIW processor using weld architecture paradigm AU - Ozer, E AU - Conte, TM T2 - IEEE TRANSACTIONS ON PARALLEL AND DISTRIBUTED SYSTEMS AB - This paper presents a cost-effective and high-performance dual-thread VLIW processor model. The dual-thread VLIW processor model is a low-cost subset of the Weld architecture paradigm. It supports one main thread and one speculative thread running simultaneously in a VLIW processor with a register file and a fetch unit per thread along with memory disambiguation hardware for speculative load and store operations. This paper analyzes the performance impact of the dual-thread VLIW processor, which includes analysis of migrating disambiguation hardware for speculative load operations to the compiler and of the sensitivity of the model to the variation of branch misprediction, second-level cache miss penalties, and register file copy time. Up to 34 percent improvement in performance can be attained using the dual-thread VLIW processor when compared to a single-threaded VLIW processor model. DA - 2005/12// PY - 2005/12// DO - 10.1109/TPDS.2005.150 VL - 16 IS - 12 SP - 1132-1142 SN - 1045-9219 KW - multithreaded processors KW - VLIW architectures KW - modeling of computer architecture ER - TY - JOUR TI - Fault analysis on distribution feeders with distributed generators AU - Baran, ME AU - El-Markaby, I T2 - IEEE TRANSACTIONS ON POWER SYSTEMS AB - This paper shows that the current an inverter interfaced distributed generator (IIDG) contributes to a fault varies considerably, due mainly to fast response of its controller. This paper proposes a method to extend the conventional fault analysis methods so that IIDG contribution can be estimated in the fault analysis. The proposed method gives rms profiles of the fault currents of interest (IIDG contribution and the fault currents the protective device will see). Test results, based on a prototype feeder, show that the proposed approach can estimate the fault current's contributions under both balanced and unbalanced fault conditions. DA - 2005/11// PY - 2005/11// DO - 10.1109/TPWRS.2005.857940 VL - 20 IS - 4 SP - 1757-1764 SN - 1558-0679 KW - distributed generation KW - distribution system KW - fault analysis ER - TY - JOUR TI - Demystifying 3D ICs: The procs and cons of going vertical AU - Davis, WR AU - Wilson, J AU - Mick, S AU - Xu, M AU - Hua, H AU - Mineo, C AU - Sule, AM AU - Steer, M AU - Franzon, PD T2 - IEEE DESIGN & TEST OF COMPUTERS AB - This article provides a practical introduction to the design trade-offs of the currently available 3D IC technology options. It begins with an overview of techniques, such as wire bonding, microbumps, through vias, and contactless interconnection, comparing them in terms of vertical density and practical limits to their use. We then present a high-level discussion of the pros and cons of 3D technologies, with an analysis relating the number of transistors on a chip to the vertical interconnect density using estimates based on Rent's rule. Next, we provide a more detailed design example of inductively coupled interconnects, with measured results of a system fabricated in a 0.35-μm technology and an analysis of misalignment and crosstalk tolerances. Lastly, we present a case study of a fast Fourier transform (FFT) placed and routed in a 0.18-μm through-via silicon-on-insulator (SOI) technology, comparing the 3D design to a traditional 2D approach in terms of wire length and critical-path delay. DA - 2005/// PY - 2005/// DO - 10.1109/MDT.2005.136 VL - 22 IS - 6 SP - 498-510 SN - 1558-1918 ER - TY - JOUR TI - Composition, structure, and electrical characteristics of HfO2 gate dielectrics grown using the remote- and direct-plasma atomic layer deposition methods AU - Kim, J. AU - Kim, S. AU - Kang, H. AU - Choi, J. AU - Jeon, H. AU - Cho, M. AU - Chung, K. AU - Back, S. AU - Yoo, K. AU - Bae, C. T2 - Journal of Applied Physics DA - 2005/// PY - 2005/// VL - 98 IS - 9 ER - TY - JOUR TI - Approach for investigating lateral conduction in self-assembled monolayers AU - Gowda, S AU - Mathur, G AU - Li, Q AU - Surthi, S AU - Misra, V T2 - APPLIED PHYSICS LETTERS AB - Lateral conductivity within a monolayer is a key factor in the implementation of emerging dense molecular memory devices since it determines the degree of cross talk between cells. Lateral interactions within a monolayer could also lead to loss of charge through defective sites. Existing characterization techniques are limited to probing the electrical communication between molecules and attached electrodes. In this paper we demonstrate a test structure consisting of n type and p type doped silicon islands to isolate vertical conduction from lateral conduction. This structure is a useful characterization tool for tailoring the intrinsic properties of the molecules for information storage. DA - 2005/12/26/ PY - 2005/12/26/ DO - 10.1063/1.2152112 VL - 87 IS - 26 SP - SN - 1077-3118 ER - TY - JOUR TI - An electronically tunable microstrip bandpass filter using thin-film barium-strontium-titanate (BST) varactors AU - Nath, J AU - Ghosh, D AU - Maria, JP AU - Kingon, AI AU - Fathelbab, W AU - Franzon, PD AU - Steer, MB T2 - IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES AB - A tunable third-order combline bandpass filter using thin-film barium-strontium-titanate varactors and fabricated on a sapphire substrate is reported. Application of 0-200-V bias varied the center frequency of the filter from 2.44 to 2.88 GHz (16% tuning) while achieving a 1-dB bandwidth of 400 MHz. The insertion loss varied from 5.1 dB at zero bias to 3.3 dB at full bias, while the return loss exceeded 13 dB over the range. The third-order intercept of the filter was found to be 41 dBm. DA - 2005/9// PY - 2005/9// DO - 10.1109/TMTT.2005.854196 VL - 53 IS - 9 SP - 2707-2712 SN - 1557-9670 KW - barium strontium titanate (BST) KW - combline filter KW - ferroelectric films KW - intermodulation distortion KW - microstrip filters KW - resonators KW - thin-film devices KW - tunable filters KW - varactor ER - TY - CHAP TI - Trellis-based virtual regular addressing structures in self-organized networks AU - Ridoux, J. AU - Fladenmuller, A. AU - Viniotis, Y. AU - Salamatian, K. T2 - Networking 2005: Networking technologies, services, and protocols: Performance of computer and communication networks: Mobile and wireless communication systems: 4th International IFIP-TC6 Networking Conference, Waterloo, Canada, May 2-6, 2005: Proceedings (Lecture notes in computer science; 3462) AB - Self–Organized Networks are multi-hop networks that do not rely on any infrastructure. Moreover, their topology is supposed to be flat since all nodes are equally in charge of address allocation and routing functions. Their time–changing topology breaks the association between Identification and Location that is present in the IP address. Moreover, mobility can not be handled easily when the addressing space is based on a tree description. In this paper we propose the use of Virtual Regular Structures to provide desired properties for Self0–Organized Networks. Our approach opens new ways to build addressing spaces and enables an implementation based on trellis graphs. We propose a construction heuristic and evaluate its performance via simulations. We also analyze the robustness of the proposed approach with regards to mobility. CN - TK5105.5 .N49 2005 PY - 2005/// DO - 10.1007/11422778_41 VL - 3462 SP - 511-522 PB - Berlin; New York: Springer SN - 3540258094 ER - TY - JOUR TI - Refractive indices of ZnSiN2 on r-plane sapphire AU - Cook, B. P. AU - Everitt, H. O. AU - Avrutsky, I. AU - Osinsky, A. AU - Cai, A. AU - Muth, J. F. T2 - Applied Physics Letters AB - II – IV – N 2 wide band gap semiconductors such as ZnSiN2, ZnGeN2, and ZnSiGeN2 have potential uses for nonlinear materials and as lattice matching compounds for the growth of SiC and GaN devices. In this study, the dispersion of the TE and TM indices of refraction has been measured systematically using the prism coupling technique for an orthorhombic ZnSiN2 epitaxial layer grown on r-plane sapphire. The resulting index dispersion is extracted from the measured optical modes using a layered biaxial waveguide analysis, which shows that although the ZnSiN2 crystal is orthorhombic, for practical purposes it can be treated as a uniaxial material. DA - 2005/3/21/ PY - 2005/3/21/ DO - 10.1063/1.1865325 VL - 86 IS - 12 SP - 121906 J2 - Appl. Phys. Lett. LA - en OP - SN - 0003-6951 1077-3118 UR - http://dx.doi.org/10.1063/1.1865325 DB - Crossref ER - TY - JOUR TI - Quantum transport for a Bloch electron quasiparticle in an inhomogeneous electric field scattering from a random distribution of impurities: A Wigner approach AU - Krieger, JB AU - Kiselev, AA AU - Iafrate, GJ T2 - PHYSICAL REVIEW B AB - The quantum transport equation is derived in terms of the Wigner distribution function for a Bloch electron quasiparticle, that is, a Bloch electron in a single band, interacting with a random, inhomogeneous distribution of impurities, and subject to general homogeneous and inhomogeneous electric fields. The time dependent homogeneous electric field is described through the vector potential gauge. The derivation of the transport equation makes use of a unitary transformation of the Liouville equation based on the interaction picture to a form in which the scattering interaction appears quadratically, and utilizes accelerated Bloch states as basis states; the resulting generalized drift and diffusion terms are obtained exactly for an arbitrary band structure. In taking the limit of slowly varying inhomogeneous electric field and slowly varying scatterer density distribution, a quantum generalization of the Boltzmann-like Wigner transport equation is obtained which includes impurity-related intracollisional field effects in the collision term and a drift term comprising the total force due to both the homogeneous and inhomogeneous fields. DA - 2005/11// PY - 2005/11// DO - 10.1103/physrevb.72.195201 VL - 72 IS - 19 SP - SN - 2469-9969 ER - TY - JOUR TI - Properties of Ta-Mo alloy gate electrode for n-MOSFET AU - Lee, CK AU - Kim, JY AU - Hong, SN AU - Zhong, HC AU - Chen, B AU - Misra, V T2 - JOURNAL OF MATERIALS SCIENCE DA - 2005/5// PY - 2005/5// DO - 10.1007/s10853-005-2108-3 VL - 40 IS - 9-10 SP - 2693-2695 SN - 1573-4803 ER - TY - JOUR TI - Optimal chip-package codesign for high-performance DSP AU - Mehrotra, P AU - Rao, V AU - Conte, TM AU - Franzon, PD T2 - IEEE TRANSACTIONS ON ADVANCED PACKAGING AB - In high-performance DSP systems, the memory bandwidth can be improved using high-density interconnect technology and appropriate memory mapping. High-density MCM and flip-chip solder bump technology is used to achieve a system with an I/O bandwidth of 100 Gb/s/cm2 die. The use of DRAMs in these systems usually make the performance of these systems poor, and some algorithms make it difficult to fully utilize the available memory bandwidth. This paper presents the design of a fast Fourier transform (FFT) engine that gives SRAM-like performance in a DRAM-based system. It uses almost 100% of the available burst-mode memory bandwidth. This FFT engine can compute a million-point FFT in 1.31 ms at a sustained computation rate of 8.64 /spl times/ 10/sup 10/ floating-point operations per second (FLOPS). This is at least an order of magnitude better than conventional systems. DA - 2005/5// PY - 2005/5// DO - 10.1109/TADVP.2005.846937 VL - 28 IS - 2 SP - 288-297 SN - 1521-3323 KW - chip-package codesign KW - fast Fourier transform (FFT) KW - seamless high off-chip connectivity (SHOCC) ER - TY - JOUR TI - Nonvolatile bistability effect based on the electrically controlled phase transition in scaled magnetic semiconductor nanostructures AU - Semenov, Y. G. AU - Kim, K. W. T2 - Physical Review B AB - We explore the bistability effect in a dimensionally scaled semiconductor nanostructure consisting of a dilute magnetic semiconductor quantum dot (QD) and a reservoir of itinerant holes separated by a barrier. The bistability stems from the magnetic phase transition in the QD mediated by the changes in the hole population. Our calculation shows that when properly designed, thermodynamic equilibrium of the scaled structure can be achieved at two different configurations; i.e., the one with the QD in a ferromagnetic state with a sufficient number of holes and the other with the depopulated QD in a paramagnetic state. The parameter window suitable for this bistability formation is discussed along with the conditions for maximum robustness/nonvolatility. To examine the issue of scaling, an estimation of the bistability lifetime is made by considering the thermal fluctuation in the QD hole population via the spontaneous transitions. A numerical evaluation is carried out for a typical carrier-mediated magnetic semiconductor [e.g., (Ga,Mn)As] as well as for a hypothetical case of high Curie temperature for potential room-temperature operation. DA - 2005/11/3/ PY - 2005/11/3/ DO - 10.1103/physrevb.72.195303 VL - 72 IS - 19 SP - J2 - Phys. Rev. B LA - en OP - SN - 1098-0121 1550-235X UR - http://dx.doi.org/10.1103/PhysRevB.72.195303 DB - Crossref ER - TY - JOUR TI - Nonlinear simulation of mixers for assessing system-level performance AU - Carvalho, NB AU - Pedro, JC AU - Jang, W AU - Steer, MB T2 - INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING AB - This article deals with nonlinear simulation methods intended to evaluate the impact of mixer nonidealities on the performance of a wireless system. Behavioral models capable of accurately describing the mixer's nonlinear dynamic features at the system level are currently unavailable. The possibility of using alternative circuit analysis techniques to reach this goal is discussed. After a brief review of existing mixer analysis methods, the focus is directed to the techniques amenable to efficiently handling periodic carriers modulated by complex stochastic signals. In particular, it is shown how multi-envelope transient methods coupled with a three-dimensional harmonic-balance engine can model a nonlinear dynamic mixer excited by a modulated RF signal accompanied by a strong adjacent channel interferer and with a local oscillator corrupted by phase noise. © 2005 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2005. DA - 2005/7// PY - 2005/7// DO - 10.1002/mmce.20091 VL - 15 IS - 4 SP - 350-361 SN - 1099-047X KW - mixers nonlinear systems KW - harmonic-balance KW - simulation techniques ER - TY - JOUR TI - Monolithically integrated boost converter based on 0.5-mu m CMOS process AU - Deng, HF AU - Duan, XM AU - Sun, N AU - Ma, Y AU - Huang, AQ AU - Chen, D T2 - IEEE TRANSACTIONS ON POWER ELECTRONICS AB - Today and in the future, a huge market arises for mobile power . Efficient performance, functionality, small profile and low cost are the most desired features for mobile power management integrated circuits. Compared with the discrete-switching dc-dc converter, monolithic integration offers many benefits and new design challenges. In this paper, a monolithically integrated high-efficiency boost dc-dc converter for nickel metal hydride or alkaline battery-powered applications is designed based on the low-voltage CMOS process. Several novel concepts are proposed for compensator design, low-voltage startup, light-load efficiency and power device optimization. DA - 2005/5// PY - 2005/5// DO - 10.1109/TPEL.2005.846551 VL - 20 IS - 3 SP - 628-638 SN - 1941-0107 KW - CMOS KW - dc-dc converter KW - monolithic ER - TY - JOUR TI - Modeling distortion in multichannel communication systems AU - Gharaibeh, KM AU - Steer, MB T2 - IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES AB - A behavioral modeling technique suited to capturing the response of wide-band multifunctional and multichannel amplifiers is introduced. The technique is based on the three-box approximation of the Volterra model and takes into account the dependence of the amplifier characteristics on frequency. The model is coupled with a new nonlinear statistical analysis, which enables accurate estimation of intermodulation and cross-modulation distortions of multiple digitally modulated signals. The model parameters can be obtained using simple measurements. DA - 2005/5// PY - 2005/5// DO - 10.1109/TMTT.2005.847064 VL - 53 IS - 5 SP - 1682-1692 SN - 1557-9670 KW - behavioral modeling code division multiple access (CDMA) KW - cross-modulation distortion KW - multichannel KW - nonlinear systems KW - power amplifiers KW - statistical modeling ER - TY - JOUR TI - Fast incorporation of optical flow into active polygons AU - Unal, G AU - Krim, H AU - Yezzi, A T2 - IEEE TRANSACTIONS ON IMAGE PROCESSING AB - In this paper, we first reconsider, in a different light, the addition of a prediction step to active contour-based visual tracking using an optical flow and clarify the local computation of the latter along the boundaries of continuous active contours with appropriate regularizers. We subsequently detail our contribution of computing an optical flow-based prediction step directly from the parameters of an active polygon, and of exploiting it in object tracking. This is in contrast to an explicitly separate computation of the optical flow and its ad hoc application. It also provides an inherent regularization effect resulting from integrating measurements along polygon edges. As a result, we completely avoid the need of adding ad hoc regularizing terms to the optical flow computations, and the inevitably arbitrary associated weighting parameters. This direct integration of optical flow into the active polygon framework distinguishes this technique from most previous contour-based approaches, where regularization terms are theoretically, as well as practically, essential. The greater robustness and speed due to a reduced number of parameters of this technique are additional and appealing features. DA - 2005/6// PY - 2005/6// DO - 10.1109/TIP.2005.847286 VL - 14 IS - 6 SP - 745-759 SN - 1941-0042 KW - level-set methods KW - motion estimation KW - object tracking KW - optical flow KW - polygon evolution KW - region-based active contours ER - TY - JOUR TI - Direct electrical measurement of the electron g factor in ultra-thin InGaAs/InP single quantum wells AU - Croke, ET AU - Schwartz, RN AU - Shi, B AU - Narayanan, AA AU - Kiselev, AA AU - Gyure, MF T2 - MICROELECTRONICS JOURNAL AB - The Landé g factor has been measured for electrons in ultra-thin InGaAs/InP quantum wells by means of an electrically-detected electron spin resonance (EDESR) technique. These experiments, carried out in a range of applied magnetic fields, allowed direct, unambiguous determination of both the absolute value and sign of the normal component of the electron g factor, g∥ (g parallel to the structure growth axis and the magnetic field). We observed a linear magnetic field dependence to the g factor, in agreement with the expression g∥(B,N)=g∥0+c(N+1/2)B, where N is the Landau level index. DA - 2005/// PY - 2005/// DO - 10.1016/j.mejo.2005.02.027 VL - 36 IS - 3-6 SP - 379-382 SN - 0026-2692 KW - g factor KW - electron spin resonance KW - InGaAs KW - quanturn well KW - spintronics ER - TY - JOUR TI - Control gain adaptation in virtual reality mediated human-telerobot interaction AU - Sheik-Nainar, MA AU - Kaber, DB AU - Chow, MY T2 - HUMAN FACTORS AND ERGONOMICS IN MANUFACTURING AB - The Internet connects millions of computers worldwide, and provides a new potential working environment for remote-controlled telerobotic systems. The main limitation of using the Internet in this application is random delays between communicating nodes, which can cause disturbances in human–machine interaction and affect telepresence experiences. This is particularly important in systems integrating virtual reality technology to present interfaces. Telepresence, or the sense of presence in a remote environment, hypothetically is positively related to teleoperation task performance. This research evaluated the effect of constant and random network (communication) delays on remote-controlled telerover performance, operator workload, and telepresence experiences. The research also assessed the effect of using a system gain adaptation algorithm to offset the negative impact of communication delays on the various response measures. It was expected that with gain adaptation, system stability, performance, and user telepresence experiences would improve with a corresponding decrease in workload. Results indicated that gain adaptation had a significant effect on the performance measures. The study demonstrated that gain adaptation could reduce deterioration in telepresence experiences and improve user performance in teleoperated and telerobotic control. © 2005 Wiley Periodicals, Inc. Hum Factors Man 15: 259–274, 2005. DA - 2005/// PY - 2005/// DO - 10.1002/hfm.20025 VL - 15 IS - 3 SP - 259-274 SN - 1090-8471 ER - TY - JOUR TI - Biotechnological improvement of cotton fibre maturity AU - Haigler, CH AU - Zhang, DH AU - Wilkerson, CG T2 - PHYSIOLOGIA PLANTARUM AB - This mini‐review focuses on the prospects and tools for controlling cotton fibre secondary wall thickness. Cotton fibre secondary walls are composed of almost 100% cellulose, and are responsible for fibre maturity and a large component of fibre yield. Improved fibre yield and maturity would result from the ability to control secondary wall cellulose deposition quantitatively, including making the process less sensitive to environmental stress. Both genetic engineering and marker‐assisted breeding are possible avenues for effecting such improvements, but first key genes that participate in the regulation and control of secondary wall cellulose biogenesis must be identified. Recent advances towards understanding and manipulating cotton fibre secondary wall deposition that are discussed here include: (i) experimental approaches to identify metabolic participants in cellulose biogenesis; (ii) isolation and characterization of promoters to drive foreign gene expression preferentially during secondary wall deposition; and (iii) a novel set of cDNA sequences representing genes that are differentially expressed during cotton fibre secondary wall deposition compared with primary wall deposition. DA - 2005/7// PY - 2005/7// DO - 10.1111/j.1399-3054.2005.00480.x VL - 124 IS - 3 SP - 285-294 SN - 1399-3054 ER - TY - CHAP TI - Benefits of multiple battery levels for the lifetime of large wireless sensor networks AU - Sichitiu, Mihail L. AU - Dutta, R. T2 - Networking 2005: Networking technologies, services, and protocols: Performance of computer and communication networks: Mobile and wireless communication systems: 4th International IFIP-TC6 Networking Conference, Waterloo, Canada, May 2-6, 2005: Proceedings (Lecture notes in computer science; 3462) AB - In large wireless sensor networks, the few nodes close to the monitoring station are likely to prove the bottleneck in the useful lifetime of the network. We examine a strategy of equipping these nodes with a larger share of the total initial energy (battery) than the others, and generalizing this notion to the rest of the network. We solve a design problem involving optimizing the network lifetime using no more than a given number of distinct battery levels, and verify the results from the model by direct simulation. CN - TK5105.5 .N49 2005 PY - 2005/// DO - 10.1007/11422778_133 VL - 3462 SP - 1440–1444 PB - Berlin; New York: Springer SN - 3540258094 ER - TY - JOUR TI - Terahertz generation in submicron GaN diodes within the limited space-charge accumulation regime AU - Sokolov, V. N. AU - Kim, K. W. AU - Kochelap, V. A. AU - Woolard, D. L. T2 - Journal of Applied Physics AB - The conditions for microwave power generation with hot-electron transport are investigated in a submicron GaN diode when it operates in the limited space-charge accumulation (LSA) mode. Applying a transport model based on the local quasistatic approximation, the analysis shows that the nitride diodes can support the LSA mode of oscillation in the terahertz-frequency range. For a 100nm n-GaN diode with a cross section of 500μm2 and the electron density of 1×1017cm−3, the generated microwave power is estimated to be as high as ≈0.6W with the corresponding dc-to-rf conversion efficiency of ≈9% and the negative differential resistance of ≈−1.3Ω; which thus provides an efficient mechanism to achieve very high-frequency microwave generation in the nitrides. DA - 2005/9/15/ PY - 2005/9/15/ DO - 10.1063/1.2060956 VL - 98 IS - 6 SP - 064507 J2 - Journal of Applied Physics LA - en OP - SN - 0021-8979 1089-7550 UR - http://dx.doi.org/10.1063/1.2060956 DB - Crossref ER - TY - JOUR TI - Spin relaxation of two-dimensional holes in strained asymmetric SiGe quantum wells AU - Glavin, B. A. AU - Kim, K. W. T2 - Physical Review B AB - We analyze spin splitting of the two-dimensional hole spectrum in strained asymmetric SiGe quantum wells (QWs). Based on the Luttinger Hamiltonian, we obtain expressions for the spin-splitting parameters up to the third order in the in-plane hole wave vector. The biaxial strain of SiGe QWs is found to be a key parameter that controls spin splitting. Application to SiGe field-effect transistor structures indicates that typical spin splitting at room temperature varies from a few tenths of meV in the case of Si QW channels to several meV for the Ge counterparts, and can be modified efficiently by gate-controlled variation of the perpendicular confining electric field. The analysis also shows that for sufficiently asymmetric QWs, spin relaxation is due mainly to the spin-splitting related D'yakonov-Pere\ifmmode \acute{l}\else \'{l}\fi{} mechanism. In strained Si QWs, our estimation shows that the hole spin relaxation time can be on the order of 100 picoseconds at room temperature, suggesting that such structures are suitable for $p$-type spin transistor applications as well. DA - 2005/1/18/ PY - 2005/1/18/ DO - 10.1103/physrevb.71.035321 VL - 71 IS - 3 SP - J2 - Phys. Rev. B LA - en OP - SN - 1098-0121 1550-235X UR - http://dx.doi.org/10.1103/PhysRevB.71.035321 DB - Crossref ER - TY - JOUR TI - Properties of functionalized redox-active monolayers on thin silicon dioxide - A study of the. dependence of retention time on oxide thickness AU - Mathur, G AU - Gowda, S AU - Li, QL AU - Surthi, S AU - Zhao, Q AU - Misra, V T2 - IEEE TRANSACTIONS ON NANOTECHNOLOGY AB - Self-assembled monolayers of redox-active molecules were formed on varying thickness of silicon dioxide (SiO/sub 2/). Cyclic voltammetry (CyV) and impedance spectroscopy (capacitance-voltage and conductance-voltage) techniques were used to characterize these structures. The charge retention properties of these molecule-oxide-silicon capacitor structures were studied by applying oxidizing voltages in two successive CyV scans without applying a reducing voltage in between the two scans. A variation of this technique, wherein a reducing voltage is applied in the second scan, was also employed. The wait time between the two scans was varied from 0 to 300 s. The number of molecules oxidized (or reduced) in the second scan increased (or decreased) with increasing wait time, which is attributed to increasing charge leakage with increasing time. The retention properties of these structures were studied and correlated to increasing oxide thickness. It was observed that the retention times increased with increasing oxide thickness if the voltage applied during the wait time was in between the oxidation and reduction peak voltages. The molecular scalability and ability to tune the retention times by varying the oxide thickness make these Si/molecular hybrid devices attractive candidates for next-generation memory applications. DA - 2005/3// PY - 2005/3// DO - 10.1109/TNANO.2004.842056 VL - 4 IS - 2 SP - 278-283 SN - 1941-0085 KW - charge retention KW - molecular memories KW - monolayer KW - redox-active molecules ER - TY - JOUR TI - Prohibition of equilibrium spin currents in multiterminal ballistic devices AU - Kiselev, A. A. AU - Kim, K. W. T2 - Physical Review B AB - It is shown that in the multiterminal ballistic devices with intrinsic spin-orbit interaction connected to normal metal contacts there are no equilibrium spin currents present at any given electron energy. Evidently, this statement holds also after the integration over all occupied states. Based on this observation, several scenarios involving nonequilibrium spin currents are identified and further analyzed. In particular, it is shown that an arbitrary single-channel two-terminal device cannot polarize transient currents. The same is true for the single-channel output terminal of an $N$-terminal device when all $N\text{\ensuremath{-}}1$ inputs are connected in parallel. DA - 2005/4/29/ PY - 2005/4/29/ DO - 10.1103/physrevb.71.153315 VL - 71 IS - 15 SP - J2 - Phys. Rev. B LA - en OP - SN - 1098-0121 1550-235X UR - http://dx.doi.org/10.1103/PhysRevB.71.153315 DB - Crossref ER - TY - JOUR TI - On performance analysis of challenge/response based authentication in wireless networks AU - Liang, W AU - Wang, WY T2 - COMPUTER NETWORKS AB - The emergence of public access wireless networks enables ubiquitous Internet services, whereas inducing more challenges of security due to open mediums. As one of the most widely used security mechanisms, authentication is to provide secure communications by preventing unauthorized usage and negotiating credentials for verification. Meanwhile, it generates heavy overhead and delay to communications, further deteriorating overall system performance. Therefore, it is very important to have an in-depth understanding of the relationship between the security and quality of service (QoS) through the authentication in wireless networks. In this paper, we analyze the impact of authentication on the security and QoS quantitatively. First, a system model based on challenge/response authentication mechanism is introduced, which is wide applied in various mobile environments. Then, the concept of security levels is proposed to describe the protection of communications with regard to the nature of security, i.e., information secrecy, data integrity, and resource availability. Third, traffic and mobility patterns are taken into account for quantitative analysis of QoS. Finally, we provide numerical results to demonstrate the impact of security levels, mobility and traffic patterns on overall system performance in terms of authentication cost, delay, and call dropping probability. DA - 2005/6/6/ PY - 2005/6/6/ DO - 10.1016/j.comnet.2004.10.016 VL - 48 IS - 2 SP - 267-288 SN - 1872-7069 KW - wireless networks KW - challenge/response authentication KW - security association KW - performance analysis ER - TY - JOUR TI - New classes of miniaturized planar Marchand baluns AU - Fathelbab, WM AU - Steer, MB T2 - IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES AB - Three new classes of miniaturized Marchand balun are defined based on the synthesis of filter prototypes. They are suitable for mixed lumped-distributed planar realizations with small size resulting from transmission-line resonators being a quarter-wavelength long at frequencies higher than the passband center frequency. Each class corresponds to an S-plane bandpass prototype derived from the specification of transmission zero locations. A tunable 50:100-/spl Omega/ balun is realized at 1 GHz to demonstrate the advantages of the approach presented here. DA - 2005/4// PY - 2005/4// DO - 10.1109/TMTT.2005.845707 VL - 53 IS - 4 SP - 1211-1220 SN - 1557-9670 KW - high-pass/bandpass prototypes KW - Marchand balun KW - network synthesis KW - transmission zeros ER - TY - JOUR TI - Multiple signature processing-based fault detection schemes for broken rotor bar in induction motors AU - Ayhan, B AU - Chow, MY AU - Song, MH T2 - IEEE TRANSACTIONS ON ENERGY CONVERSION AB - The existence of broken rotor bars in induction motors can be detected by monitoring any abnormality of the spectrum amplitudes at certain frequencies in the motor current spectrum. It has been shown that these broken rotor bar-specific frequencies are settled around the fundamental stator current frequency and are termed lower and upper sideband components. Broken rotor bar fault detection schemes should depend on multiple signatures in order to overcome or reduce the effect of any misinterpretation of the signatures that are obscured by factors such as measurement noises and different load conditions. Multiple discriminant analysis (MDA) provides an appropriate environment to develop such fault detection schemes because of its multi-input processing capabilities. The focus of this paper is to provide a new fault detection methodology for broken rotor bar fault detection and diagnostics in terms of its multiple signature processing feature and the motor operation partitioning concept to improve the overall detection performance. This paper describes two fault detection schemes within this methodology, and demonstrates that multiple signature processing is more efficient than single signature processing. The first scheme, which will be named the "monolith scheme," is based on a single large-scale MDA unit representing the complete operating load torque region of the motor, while the second scheme, which will be named the "partition scheme," consists of many small-scale MDA units, each unit representing a particular load torque operating region. DA - 2005/6// PY - 2005/6// DO - 10.1109/TEC.2004.842393 VL - 20 IS - 2 SP - 336-343 SN - 0885-8969 KW - broken rotor bar KW - discriminant analysis KW - fault diagnosis KW - induction motors KW - monitoring ER - TY - JOUR TI - Impact of Ge on integration of HfO2 and metal gate electrodes on strained Si channels AU - Lin, YX AU - Ozturk, MC AU - Chen, B AU - Rhee, SJ AU - Lee, JC AU - Misra, V T2 - APPLIED PHYSICS LETTERS AB - Tensile-strained Si epitaxial layers (7.5nm–17nm) were grown on relaxed Si0.5Ge0.5 virtual substrates by ultrahigh-vacuum rapid thermal chemical vapor deposition. Metal-oxide-silicon capacitors were fabricated with SiO2 or HfO2 as gate dielectrics and Ru–Ta alloy or TaN as the metal gate electrodes. The results indicate that the interface trap density (Dit) increased as the strained silicon thickness decreased, which was attributed to the presence of Ge in the strained Si layer. Higher Dit was observed with SiO2 which may be due to Si consumption during oxidation, leading to a higher density of Ge at the interface. Leakage current density (Jg) was also observed to increase with increasing strained silicon thickness. This trend of increasing Dit and Jg with decreasing strained silicon thickness did not change after rapid thermal annealing. Both Ru–Ta and TaN gate electrodes were found to exhibit as good a performance on strained Si as on bulk Si. DA - 2005/8/15/ PY - 2005/8/15/ DO - 10.1063/1.2009809 VL - 87 IS - 7 SP - SN - 1077-3118 ER - TY - JOUR TI - Eulerian-Lagrangian model for predicting odor dispersion using instrumental and human measurements AU - Schiffman, S.S. AU - McLaughlin, B. AU - Katul, G.G. AU - Nagle, H.T. T2 - Sensors and Actuators B: Chemical AB - Abstract A Eulerian-Lagrangian model was used to predict the trajectory and spatial distribution of odor and odorants downwind from an industrial facility with multiple sources of odor emissions. Specifically, the model was used to simulate the dispersion of odor from a confined animal feeding operation (CAFO) under different meteorological conditions: (1) during daytime when the boundary layer is usually turbulent due to ground-level heating from solar short wave radiation, and (2) during the evening when deep surface cooling through long-wave radiation to space recreates a stable (nocturnal) boundary layer. Aerial photographs were taken of the CAFO, and the geographical area containing the odorant sources was partitioned into 10 m2 grids. Relative odorant concentrations present at each grid point that corresponded to an odor source were measured on site and then entered into a database. The predicted odor dispersion distance was found to be greater at night-time than during daytime and was consistent with field reports from individuals living near the CAFO. The model utilizes single numbers that represent relative concentrations or intensities (e.g. from an electronic nose or human judgments) to simulate downwind dispersion. The advantages of this algorithm over standard Gaussian plume models are that: the velocity variances and covariances among its three components, integral time scale (a measure of eddy coherency), and complex boundary conditions (e.g. complex release points, surface boundary conditions) are explicitly considered. DA - 2005/4// PY - 2005/4// DO - 10.1016/j.snb.2004.05.067 VL - 106 IS - 1 SP - 122-127 J2 - Sensors and Actuators B: Chemical LA - en OP - SN - 0925-4005 UR - http://dx.doi.org/10.1016/j.snb.2004.05.067 DB - Crossref KW - odor dispersion KW - odorant concentration KW - odor intensity KW - prediction of odor downwind ER - TY - JOUR TI - Coulombic effects of electron-hole plasma in nitride-based nanostructures AU - Fedorov, I. A. AU - Sokolov, V. N. AU - Kim, K. W. AU - Zavada, J. M. T2 - Journal of Applied Physics AB - We study the Coulombic effects of electron-hole plasma on the ground and first excited energy levels and carrier wave functions in a GaN∕AlGaN quantum well (QW) structure. The coupled Schrödinger equations for electron and hole states are solved self-consistently in the Hartree-Fock approximation along with the Poisson equation. As expected, the decreasing QW width and increasing plasma density diminish the charge separation in the QW induced by the internal field, leading to the relatively reduced contribution of the Hartree interaction to the energy-level shift. In contrast, the calculation also demonstrates that the contribution of many-body effects becomes more pronounced. The resulting competition between the many-body and Hartree contributions causes a nonmonotonous dependence of the electron and hole energies on the plasma density at a given field. These findings are applied to explore the potential bistable behavior in the QW electroabsorption under near-band-edge photoexcitation. DA - 2005/9/15/ PY - 2005/9/15/ DO - 10.1063/1.2060937 VL - 98 IS - 6 SP - 063711 J2 - Journal of Applied Physics LA - en OP - SN - 0021-8979 1089-7550 UR - http://dx.doi.org/10.1063/1.2060937 DB - Crossref ER - TY - JOUR TI - Characterization and modeling of AlGaN/GaN MOS capacitor with leakage for large signal transistor modeling AU - Dandu, K AU - Saripalli, Y AU - Braddock, D AU - Johnson, M AU - Barlage, DW T2 - IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS AB - Dual mode AlGaN/GaN metal oxide semiconductor (MOS) heterostructure field-effect transistor (HFET) devices were fabricated and characterized. In HFET mode of operation the devices showed an f T /spl middot/L/sub g/ product of 12GHz/spl middot/μm at Vgs=-2 V. The AlGaN devices showed formation of an accumulation layer under the gate in forward bias and a f T /spl middot/L/sub g/ product of 6GHz/spl middot/μm was measured at Vgs=5 V. A novel piecewise small signal model for the gate capacitance of MOS HFET devices is presented and procedures to extract the capacitance in presence of gate leakage are outlined. The model accurately fits measured data from 45MHz to 10GHz over the entire bias range of operation of the device. DA - 2005/10// PY - 2005/10// DO - 10.1109/LMWC.2005.856680 VL - 15 IS - 10 SP - 664-666 SN - 1531-1309 KW - AlGaN/GaN heterostructure field-effect transistors (HFETs) KW - metal oxide semiconductor (MOS) capacitors KW - modeling ER - TY - JOUR TI - An optimal design methodology for inductive power link with class-E amplifier AU - Kendir, GA AU - Liu, WT AU - Wang, GX AU - Sivaprakasam, M AU - Bashirullah, R AU - Humayun, MS AU - Weiland, JD T2 - IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS I-REGULAR PAPERS AB - This paper presents a design methodology of a highly efficient power link based on Class-E driven, inductively coupled coil pair. An optimal power link design for retinal prosthesis and/or other implants must take into consideration the allowable safety limits of magnetic fields, which in turn govern the inductances of the primary and secondary coils. In retinal prosthesis, the optimal coil inductances have to deal with the constraints of the coil sizes, the tradeoffs between the losses, H-field limitation and dc supply voltage required by the Class-E driver. Our design procedure starts with the formation of equivalent circuits, followed by the analysis of the loss of the rectifier and coils and the H-field for induced voltage and current. Both linear and nonlinear models for the analysis are presented. Based on the procedure, an experimental power link is implemented with an overall efficiency of 67% at the optimal distance of 7 mm between the coils. In addition to the coil design methodology, we are also presenting a closed-loop control of Class-E amplifier for any duty cycle and any value of the systemQ. DA - 2005/5// PY - 2005/5// DO - 10.1109/TCSI.2005.846208 VL - 52 IS - 5 SP - 857-866 SN - 1558-0806 KW - lass-E amplifier KW - closed-loop control KW - coil design KW - inductive powering KW - RF powering KW - transcutaneous links ER - TY - JOUR TI - Threshold discrimination and blanking for large near-far power ratios in UWB networks AU - Lovelace, WM AU - Townsend, JK T2 - IEEE TRANSACTIONS ON COMMUNICATIONS AB - A simple chip-discrimination technique is presented for use with ultra-wideband (UWB) impulse radio (IR) that improves performance for large near-far interference power ratios. A typical spread-spectrum IR that employs a matched-filter sum for bit decisions is susceptible to small numbers of large power pulses that can dominate the bit decision-threshold statistics. This letter describes a technique for chip discrimination prior to the spreading summation, that can greatly reduce the effects of large near-far power ratios among interferers. The technique exploits the very narrow pulsewidth and resulting low-duty-cycle characteristic only achievable with ultra-wide bandwidth. A statistical model is developed that predicts bit-error performance for binary offset pulse position modulation as a function of near-far density and power for varying discrimination thresholds. An analytic solution for perfect chip blanking is developed, and is in good agreement with chip discrimination for large near-far power ratios. We find that even a small number of very near interferers can greatly reduce the performance of a system without blanking or discrimination. Results show substantial improvement using this method for near interferers with near-far power ratios greater than 20 dB. DA - 2005/9// PY - 2005/9// DO - 10.1109/tcomm.2005.855021 VL - 53 IS - 9 SP - 1447-1450 SN - 1558-0857 KW - impulse radio (IR) KW - interference KW - networks KW - ultrawideband (UWB) radio ER - TY - JOUR TI - Thermal effects of bioimplants AU - Lazzi, G T2 - IEEE ENGINEERING IN MEDICINE AND BIOLOGY MAGAZINE AB - Implantable devices are well on the way to becoming small, dedicated, and highly complex embedded systems. As such, they are plagued by the same thermal management problems that afflict the computer industry: increased functionality causes increased heat generation. Herein, the effects of various parameters on the temperature increase in the human body tissue are considered, with a focus on a specific proposed implant: a dual-unit retinal prosthesis to restore partial vision to the blind . This particular example is educative since it includes most of the potential causes of thermal dissipation: a microchip that could dissipate relatively large power, a telemetry system, and a potentially large number of stimulating electrodes. The power dissipation characteristics of implanted electronic systems will have increasing importance for the design of future implantable devices. It was shown in this article that in some cases, this power dissipation can lead to temperature increases in the human tissue that are not negligible. In particular, the design of implantable stimulating devices with a large number of stimulating channels must be performed with a clear idea of the potential thermal implications of the device. Fortunately, reliable numerical and experimental methods are available to characterize the temperature increase caused by the implantable device. These methods should be used during the design phase of these devices. DA - 2005/// PY - 2005/// DO - 10.1109/MEMB.2005.1511503 VL - 24 IS - 5 SP - 75-81 SN - 0739-5175 ER - TY - JOUR TI - Intrinsic mobility evaluation of high-kappa gate dielectric transistors using pulsed I-d-V-g AU - Young, CD AU - Zeitzoff, P AU - Brown, GA AU - Bersuker, G AU - Lee, BH AU - Hauser, , JR T2 - IEEE ELECTRON DEVICE LETTERS AB - A novel intrinsic mobility extraction methodology for high-/spl kappa/ gate stacks that only requires a capacitance-voltage and pulsed I/sub d/-V/sub g/ measurement is demonstrated on SiO/sub 2/ and high-/spl kappa/ gate dielectric transistors and is benchmarked to other reported mobility extraction techniques. Fast transient charging effects in high-/spl kappa/ gate stacks are shown to cause the mobility extracted using conventional dc-based techniques to be lower than the intrinsic mobility. DA - 2005/8// PY - 2005/8// DO - 10.1109/LED.2005.852746 VL - 26 IS - 8 SP - 586-589 SN - 1558-0563 KW - charge trapping KW - high-kappa KW - mobility pulsed current-voltage (I-V) KW - remote scattering ER - TY - JOUR TI - Integration of authentication and mobility management in third generation and WLAN data networks AU - Wang, WY AU - Liang, W AU - Agarwal, AK T2 - WIRELESS COMMUNICATIONS & MOBILE COMPUTING AB - Abstract The successful deployment of wireless local area networks (WLAN) for high speed data transmission and cellular systems for wide coverage and global roaming has emerged to be a complementary platform for wireless data communications. In order to fully exploit potentials in 3G/WLAN integration, authentication of roaming users crossing different networks, must be coupled with mobility management, which is a challenging, yet not resolved issue. The focus of this paper is on state‐of‐art solutions to Wi‐Fi and cellular networks based on IP infrastructure. Moreover, we introduce a new authentication architecture for fast authentication during inter‐networking handoff and large‐scale heterogeneous networks. We show that the new architecture can reduce authentication latency significantly and be adaptive to user mobility and traffic. Copyright © 2005 John Wiley & Sons, Ltd. DA - 2005/9// PY - 2005/9// DO - 10.1002/wcm.335 VL - 5 IS - 6 SP - 665-678 SN - 1530-8677 KW - authentication KW - mobility management KW - 3G systems KW - wireless local area networks (WLANs) ER - TY - JOUR TI - Information-theoretic active polygons for unsupervised texture segmentation AU - Unal, G AU - Yezzi, A AU - Krim, H T2 - INTERNATIONAL JOURNAL OF COMPUTER VISION AB - Curve evolution models used in image segmentation and based on image region information usually utilize simple statistics such as means and variances, hence can not account for higher order nature of the textural characteristics of image regions. In addition, the object delineation by active contour methods, results in a contour representation which still requires a substantial amount of data to be stored for subsequent multimedia applications such as visual information retrieval from databases. Polygonal approximations of the extracted continuous curves are required to reduce the amount of data since polygons are powerful approximators of shapes for use in later recognition stages such as shape matching and coding. The key contribution of this paper is the development of a new active contour model which nicely ties the desirable polygonal representation of an object directly to the image segmentation process. This model can robustly capture texture boundaries by way of higher-order statistics of the data and using an information-theoretic measure and with its nature of the ordinary differential equations. This new variational texture segmentation model, is unsupervised since no prior knowledge on the textural properties of image regions is used. Another contribution in this sequel is a new polygon regularizer algorithm which uses electrostatics principles. This is a global regularizer and is more consistent than a local polygon regularization in preserving local features such as corners. DA - 2005/// PY - 2005/// DO - 10.1007/s11263-005-4880-6 VL - 62 IS - 3 SP - 199-220 SN - 1573-1405 KW - region-based active contours KW - unsupervised segmentation KW - texture segmentation KW - polygon evolution KW - information theoretic measure KW - electrostatic regularizer ER - TY - JOUR TI - Evaluation of nickel and molybdenum silicides for dual gate complementary metal-oxide semiconductor application AU - Biswas, N AU - Gurganus, J AU - Misra, V AU - Yang, Y AU - Stemmer, S T2 - APPLIED PHYSICS LETTERS AB - Characteristics of NiSi and MoSi via full consumption of undoped silicon layers have been studied. Interaction of nickel (Ni) and molybdenum (Mo) silicides with SiO2 was evaluated in terms of work function and thermal stability. For nickel silicide, the work function values were low for samples annealed at 400 °C even after full consumption of silicon. The work function increased with the anneal temperature and stabilized at 600 °C to close to midgap values. Dielectric interaction as a result of silicide formation was studied using current–voltage characteristics. Low leakage currents in these stacks indicated minimum dielectric damage due to silicided gates. Silicidation of Mo was found to be incomplete as the capacitance–voltage curves were marked with larger EOT values and negative shifts in the flatband voltages even at 700 °C. Auger depth profiling, high resolution transmission electron microscopy (HRTEM) and x-ray diffraction (XRD) were used for material analysis of the silicided gate stacks. DA - 2005/1/10/ PY - 2005/1/10/ DO - 10.1063/1.1849850 VL - 86 IS - 2 SP - SN - 1077-3118 ER - TY - JOUR TI - Characteristics of HfO2 thin films grown by plasma atomic layer deposition AU - Kim, J. AU - Kim, S. AU - Jeon, H. AU - Cho, M. H. AU - Chung, K. B. AU - Bae, C. T2 - Applied Physics Letters DA - 2005/// PY - 2005/// VL - 87 IS - 5 ER - TY - JOUR TI - A unified model for the performance analysis of IEEE 802.11e EDCA AU - Hui, J AU - Devetsikiotis, M T2 - IEEE TRANSACTIONS ON COMMUNICATIONS AB - Rapid deployment of IEEE 802.11 wireless local area networks (WLANs) and their increasing quality of service (QoS) requirements motivate extensive performance evaluations of the upcoming 802.11e QoS-aware enhanced distributed coordination function (EDCA). Most of the analytical studies up-to-date have been based on one of the three major performance models in legacy distributed coordination function analysis, requiring a large degree of complexity in solving multidimensional Markov chains. Here, we expose the common guiding principle behind these three seemingly different models. Subsequently, by abstracting, unifying, and extending this common principle, we propose a new unified performance model and analysis method to study the saturation throughput and delay performance of EDCA, under the assumption of a finite number of stations and ideal channel conditions in a single-hop WLAN. This unified model combines the strengths of all three models, and thus, is easy to understand and apply; on the other hand, it helps increase the understanding of the existing performance analysis. Despite its appealing simplicity, our unified model and analysis are validated very well by simulation results. Ultimately, by means of the proposed model, we are able to precisely evaluate the differentiation effects of EDCA parameters on WLAN performance in very broad settings, a feature which is essential for network design. DA - 2005/9// PY - 2005/9// DO - 10.1109/tcomm.2005.855013 VL - 53 IS - 9 SP - 1498-1510 SN - 1558-0857 KW - enhanced distributed coordination function (EDCA) KW - IEEE 802.11 KW - performance analysis KW - quality of service (QoS) KW - wireless local area network (WLAN) ER - TY - JOUR TI - The impact of RF front-end characteristics on the spectral regrowth of communications signals AU - Gard, KG AU - Larson, LE AU - Steer, MB T2 - IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES AB - The nonlinear characteristic of an RF front-end results in in-band distortion and spectral regrowth of digitally modulated signals with distortion being dependent on the statistical variation of the signal. In this paper, the interaction of the nonlinear response with the signal is explored using a time-averaged autocorrelation analysis applied to several limiter-amplifier models having characteristics ranging from soft-to-hard amplitude limiting. The analysis is verified by comparing measured and predicted adjacent channel power rejection for a code-division multiple-access amplifier. DA - 2005/6// PY - 2005/6// DO - 10.1109/TMTT.2005.848801 VL - 53 IS - 6 SP - 2179-2186 SN - 1557-9670 KW - adjacent channel interference KW - adjacent channel power ratio (ACPR) KW - autocorrelation function KW - bandpass nonlinearity KW - behavioral models KW - cellular radio KW - code-division multiple-access (CDMA) signal KW - code division multiple access KW - complex Gaussian process KW - correlation KW - correlation theory KW - digital radio KW - digital radio system KW - digital signals KW - digitally modulated carrier KW - Gaussian processes KW - limiting amplifier KW - limiting-amplifier model KW - microwave amplifiers KW - modulation KW - nonlinear amplifier KW - nonlinear distortion KW - nonlinear transformation KW - quadrature input signal KW - RF envelope model KW - spectral analysis KW - spectral regrowth KW - statistical analysis ER - TY - JOUR TI - Surface characteristics of indium-tin oxide cleaned by remote plasma AU - Kim, S. AU - Seo, H. AU - Kim, Y. AU - Kim, K. AU - Tak, Y. AU - Jeon, H. T2 - Japanese Journal of Applied Physics. Part 1, Regular Papers, Short Notes & Review Papers DA - 2005/// PY - 2005/// VL - 44 IS - 2 SP - 1041-1044 ER - TY - JOUR TI - Seeded growth of bulk AlN crystals and grain evolution in polycrystalline AlN boules AU - Noveski, V AU - Schlesser, R AU - Raghothamachar, B AU - Dudley, M AU - Mahajan, S AU - Beaudoin, S AU - Sitar, Z T2 - JOURNAL OF CRYSTAL GROWTH AB - Large AlN crystals were grown by powder sublimation in a nitrogen atmosphere at low supersaturation and growth rates of 0.1–0.3 mm/h. The starting deposition surface was a sintered TaC disc. An appropriate adjustment of the system pressure and source-seed temperature gradient during the early stages of growth allowed epitaxial re-growth on AlN seeds that had been exposed to air. Single-crystalline AlN grains of 1 cm in size were achieved through multiple sublimation growth runs conducted at P=500Torr and growth temperatures of 2050–2150 °C. Elemental analysis of impurities in the grown AlN boules confirmed low oxygen contamination levels of ∼1019/cm3. No discontinuities were introduced in the structural defect distribution in the individual single-crystalline grains by the multiple re-growth steps. Absence of preferred growth directions of grains suggest the epitaxial re-growth process is suitable for seeded single-crystal growth in any orientation. DA - 2005/5/15/ PY - 2005/5/15/ DO - 10.1016/j.jcrysgro.2004.12.027 VL - 279 IS - 1-2 SP - 13-19 SN - 0022-0248 KW - bulk AlN KW - single crystal KW - seeded growth KW - sublimation growth ER - TY - JOUR TI - Increasing wireless channel capacity through MIMO systems employing co-located antennas AU - Konanur, AS AU - Gosalia, K AU - Krishnamurthy, SH AU - Hughes, B AU - Lazzi, G T2 - IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES AB - Wireless networks consisting of compact antennas find applications in diverse areas such as communication systems, direction of arrival estimation, sensor networks, and imaging. The effectiveness of many of these systems depend on maximizing the reception of RF power and extracting maximum information from the incident electromagnetic (EM) wave. Traditionally, this has been achieved through multiple-input multiple-output (MIMO) systems employing a spatial array of antennas that enhance the channel capacity. In this paper, we report similar increases in channel capacity obtained through the use of vector antennas consisting of co-located loops and dipoles, which can respond to more than one component of the EM field. It is shown that systems with three- and four-element vector antennas at both the transmitter and receiver operating around the frequency of 2.25 GHz support three and four times more information, respectively, as compared to conventional systems consisting of sensors with single antennas. Comparison with a simplified theoretical model of a MIMO system with co-located antennas in a rich multipath environment shows good agreement. DA - 2005/6// PY - 2005/6// DO - 10.1109/TMTT.2005.848105 VL - 53 IS - 6 SP - 1837-1844 SN - 1557-9670 KW - loop antenna KW - multiple-input multiple-output (MIMO) antenna KW - vector antenna ER - TY - JOUR TI - Suppression of parasitic Si substrate oxidation in HfO2-ultrathin-Al2O3-Si structures prepared by atomic layer deposition AU - Park, M. AU - Koo, J. AU - Kim, J. AU - Jeon, H. AU - Bae, C. AU - Krug, C. T2 - Applied Physics Letters DA - 2005/// PY - 2005/// VL - 86 IS - 25 ER - TY - JOUR TI - Supporting demanding hard-real-time systems with STI AU - Welch, BJ AU - Kanaujia, SO AU - Seetharam, A AU - Thirumalai, D AU - Dean, AG T2 - IEEE TRANSACTIONS ON COMPUTERS AB - Software thread integration (STI) is a compilation technique which enables the efficient use of an application's fine-grain idle time on generic processors without special hardware support. With STI, a primary function is automatically interleaved with a secondary function to create a single implicitly multithreaded function which minimizes context switching and, hence, both improves performance and also offers very fine-grain concurrency. In this work, we extend STI techniques to address two challenges. First, we reduce response time for interrupts or other high-priority threads by introducing polling servers into integrated threads. Second, we enable integration with long host threads, expanding the domain of STI. We derive methods to evaluate the response time for threads in systems with and without these new integration methods. We demonstrate these concepts with the integration of various threads in a sample hard-real-time system on a highly-constrained microcontroller. We use an inexpensive 20 MHz AVR 8-bit microcontroller to generate monochrome NTSC video while servicing a high-speed (115,2 kbaud) serial communication link. We have built and tested this system, achieving graphics rendering speed-ups of 3.99/spl times/ to 13.5/spl times/. DA - 2005/10// PY - 2005/10// DO - 10.1109/TC.2005.169 VL - 54 IS - 10 SP - 1188-1202 SN - 1557-9956 KW - software thread integration KW - embedded systems KW - fine-grain concurrency KW - post-pass compiler KW - hardware-to-software migration ER - TY - JOUR TI - Substrate voltage and accumulation-mode MOS varactor capacitance AU - Wartenberg, S. A. AU - Hauser, J. R. T2 - IEEE Transactions on Electron Devices AB - To adjust the capacitance of an accumulation-mode MOS varactor, a voltage is applied to the drain/source with the gate grounded. In this novel arrangement, a voltage is applied to the gate V/sub gate/ and another to the substrate V/sub sub/ with the drain/source grounded. Applying V/sub sub/ between the p/sup +/-type substrate and the varactor's n-well adjusts the minimum capacitance C/sub min/ and flattens the overall capacitance-voltage (C-V) curve over a wide range of negative V/sub gate/. Measurements show the tuning range using V/sub sub/ to be as wide as that using V/sub gate/. By tuning with V/sub sub/, the capacitance C/sub min/ is constant over a range of negative V/sub gate/. In this region, it may be possible to apply a large ac signal on V/sub gate/ without modulating the capacitance. To illustrate this technique, C-V measurements of a MOS varactor are simulated in a differential LC-tank VCO circuit. Simulations show how adjusting both V/sub gate/ and V/sub sub/ alters the oscillation frequency. DA - 2005/// PY - 2005/// DO - 10.1109/TED.2005.850953 VL - 52 IS - 7 SP - 1563-1567 ER - TY - JOUR TI - Nickel germanosilicide contacts formed on heavily boron doped Si1-xGex source/drain junctions for nanoscale CMOS AU - Liu, J AU - Ozturk, MC T2 - IEEE TRANSACTIONS ON ELECTRON DEVICES AB - Formation of source/drain junctions with a small parasitic series resistance is one of the key challenges for CMOS technology nodes beyond 100 nm. A new source/drain technology based on selective deposition of heavily in situ doped Si/sub 1-x/Ge/sub x/ layers was recently developed in this laboratory. This paper presents formation and structural characterization of self-aligned nickel germanosilicide contacts formed on heavily boron doped Si/sub 1-x/Ge/sub x/ alloys. The results show that thin NiSi/sub 1-x/Ge/sub x/ contacts with a resistivity of /spl sim/25 /spl mu//spl Omega/-cm can be formed on Si/sub 1-x/Ge/sub x/ alloys at temperatures as low as 350/spl deg/C. However, the low resistivity and the structural integrity of the NiSi/sub 1-x/Ge/sub x/ films can be maintained up to a maximum temperature of 450/spl deg/C. At higher temperatures, Ge out-diffusion from NiSi/sub 1-x/Ge/sub x/ grains results in interface roughening and NiSi spikes. If the maximum processing temperature is kept within 400/spl deg/C, p/sup +/-n junctions with excellent leakage behavior can be formed. A minimum contact resistivity of 2/spl times/10/sup -8/ /spl Omega/-cm/sup 2/ is demonstrated for Ge concentrations above /spl sim/40%, which can be linked to the smaller semiconductor bandgap and high boron activation under the metal contact. The results suggest that NiSi/sub 1-x/Ge/sub x/ contacts formed on Si/sub 1-x/Ge/sub x/ junctions have the potential to satisfy the contact resistivity requirements of future CMOS technology nodes. DA - 2005/7// PY - 2005/7// DO - 10.1109/TED.2005.850613 VL - 52 IS - 7 SP - 1535-1540 SN - 1557-9646 KW - contact resistance KW - germanosilicide KW - nickel KW - source/drain KW - ultra-shallow junction ER - TY - JOUR TI - Network decomposition: Theory and practice AU - Eun, DY AU - Shroff, NB T2 - IEEE-ACM TRANSACTIONS ON NETWORKING AB - We show that significant simplicities can be obtained for the analysis of a network when link capacities are large enough to carry many flows. We develop a network decomposition approach in which network analysis can be greatly simplified. We prove that the queue length at the downstream queue converges to that of a single queue obtained by removing the upstream queue, as the capacity and the number of flows at the upstream queue increase. The precise modes of convergence vary depending on the type of input traffic, i.e., from regulated traffic arrivals to point process inputs. Our results thus help simplify network analysis by decomposing the original network into a simplified network in which all the nodes with large capacity have been eliminated. By means of extensive numerical investigation under various network scenarios, we demonstrate different aspects and implications of our network decomposition approach. Some of our findings are that our techniques perform well especially for the cases when: i) many flows are multiplexed as they enter the queue and/or ii) departing flows are routed to different downstream nodes, i.e., no single flow dominates at any node. DA - 2005/6// PY - 2005/6// DO - 10.1109/TNET.2005.850218 VL - 13 IS - 3 SP - 526-539 SN - 1558-2566 KW - aggregation KW - many-sources-asymptotic KW - network decomposition KW - overflow probability KW - performance analysis ER - TY - JOUR TI - Modeling network traffic with long range dependence: characterization, visualization and tools AU - Devetsikiotis, M AU - Fonseca, NLS T2 - COMPUTER NETWORKS DA - 2005/6/21/ PY - 2005/6/21/ DO - 10.1016/j.comnet.2005.01.001 VL - 48 IS - 3 SP - 289-291 SN - 1872-7069 ER - TY - JOUR TI - In situ selectivity and thickness monitoring during selective silicon epitaxy using quadrupole mass spectrometry and wavelets AU - Rying, EA AU - Ozturk, MC AU - Bilbro, GL AU - Lu, JC T2 - IEEE TRANSACTIONS ON SEMICONDUCTOR MANUFACTURING AB - This work reports on a novel in situ sensing technique for monitoring the thickness of selectively grown Si epitaxial layers. The technique can be extended to detect selectivity loss when Si nuclei begin to appear on the insulator surface. In this technique, a quadruple mass spectrometer (QMS) monitors the ionized molecular hydrogen (H/sub 2//sup +/) signal, which is a by-product of the chemical-vapor deposition process. The thickness of the epitaxial layer is determined by evaluating the area under the hydrogen signal. We have deliberately used silane (SiH/sub 4/) without HCl or Cl/sub 2/ to achieve both nonselective and selective depositions. We also show that the amount of hydrogen produced by the deposition process is a strong function of the exposed Si area on the wafer and the effect can be accurately monitored by QMS. This finding was exploited to develop an in situ sensing method to detect the selectivity loss. When selectivity is lost, Si nuclei begin to form on the insulator surface increasing the effective Si area on the wafer. Consequently, the rate of hydrogen production increases rapidly as nuclei coalesce, resulting in a distinct change in the functional form of the hydrogen signal. The hydrogen signal was analyzed using an automatic edge detection procedure based on the wavelet transform modulus maxima representation. The technique facilitated the determination of selective film thickness from the time-integrated hydrogen (H/sub 2//sup +/) signal. To the authors' knowledge, This work represents one of the first applications of wavelets to in situ process monitoring and fault detection in semiconductor manufacturing. The authors expect the methodology presented in This work to be readily transferable to other selective deposition processes, including those that utilize dichlorosilane and disilane since hydrogen is a by-product of those processes as well. DA - 2005/2// PY - 2005/2// DO - 10.1109/TSM.2004.836660 VL - 18 IS - 1 SP - 112-121 SN - 1558-2345 KW - edge detection KW - in situ selectivity loss detection KW - rapid thermal chemical-vapor deposition KW - selective silicon epitaxy KW - wavelet transform modulus maxima ER - TY - JOUR TI - Impedance matching and implementation of planar space-filling dipoles as intraocular implanted antennas in a retinal prosthesis AU - Gosalia, K AU - Humayun, MS AU - Lazzi, G T2 - IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION AB - In this work, an extremely compact planar meander line dipole is designed and implemented for use as an intraocular element in a retinal prosthesis. This planar meander dipole antenna exhibits a high degree of current vector alignment and is impedance matched by inducing a current phase reversal along its length. This current phase reversal is induced by a minor offset in feed location which yields a highly directive broadside radiation pattern on this particular planar antenna geometry. This concept is applied in designing and implementing a 6/spl times/6 mm planar compact wire dipole at 1.4 GHz as the intraocular element for the data telemetry link of a retinal prosthesis. Coupling measurements between an external microstrip patch antenna and the intraocular wire dipole are presented and compared with those obtained with intraocular microstrip patch antennas in place of the wire dipole. It is demonstrated that such compact meander dipoles can perform better than previously reported microstrip patch antennas as intraocular elements for a retinal prosthesis. DA - 2005/8// PY - 2005/8// DO - 10.1109/TAP.2005.852514 VL - 53 IS - 8 SP - 2365-2373 SN - 1558-2221 KW - implanted antennas KW - miniature antennas KW - planar meander dipole antennas KW - retinal prosthesis ER - TY - JOUR TI - Growth of ZnO films on C-plane (0001) sapphire by pulsed electron deposition (PED) AU - Porter, HL AU - Mion, C AU - Cai, AL AU - Zhang, X AU - Muth, JF T2 - MATERIALS SCIENCE AND ENGINEERING B-SOLID STATE MATERIALS FOR ADVANCED TECHNOLOGY AB - Thin films of ZnO on C-plane (0 0 0 1) sapphire (α-Al2O3) substrates were grown by pulsed electron beam deposition (PED). Intense electron pulses, approximately 0.8 J/70 ns pulse produced by a channelspark pulsed electron source at a rate of 10 Hz were used to ablate sintered polycrystalline ZnO targets at an oxygen pressure of 15 mTorr. During growth, the sapphire substrate temperature was maintained at 700 °C. A 15 min growth produced a 250 nm film, as measured by a Dektak profilometer. Measurements by X-ray diffraction indicate c-axis oriented films. Cathodoluminescence (CL) data show strong band edge emission. Optical absorption data indicate a sharp band edge with clearly visible exciton absorption at room temperature, and resolved A and B excitons at 77 K. Thus, pulsed electron beam deposition of ZnO films is shown to be a viable technique for producing high quality ZnO films. DA - 2005/5/25/ PY - 2005/5/25/ DO - 10.1016/j.mseb.2005.02.042 VL - 119 IS - 2 SP - 210-212 SN - 0921-5107 KW - pulsed electron deposition KW - cathodoluminescence KW - pulsed laser deposition ER - TY - JOUR TI - Fabrication of wafer scale, aligned sub-25 nm nanowire and nanowire templates using planar edge defined alternate layer process AU - Sonkusale, , SR AU - Amsinck, CJ AU - Nackashi, DP AU - Di Spigna, NH AU - Barlage, D AU - Johnson, M AU - Franzon, PD T2 - PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES AB - We have demonstrated a new planar edge defined alternate layer (PEDAL) process to make sub-25 nm nanowires across the whole wafer. The PEDAL process is useful in the fabrication of metal nanowires directly onto the wafer by shadow metallization and has the ability to fabricate sub-10 nm nanowires with 20 nm pitch. The process can also be used to make templates for the nano-imprinting with which the crossbar structures can be fabricated. The process involves defining the edge by etching a trench patterned by conventional i-line lithography, followed by deposition of alternating layers of silicon nitride and crystallized a-Si. The thickness of these layers determines the width and spacing of the nanowires. Later the stack is planarized to the edge of the trench by spinning polymer Shipley 1813 and then dry etching the polymer, nitride and polysilicon stack with non-selective RIE etch recipe. Selective wet etch of either nitride or polysilicon gives us the array of an aligned nanowires template. After shadow metallization of the required metal, we get metal nanowires on the wafer. The process has the flexibility of routing the nanowires around the logic and memory modules all across the wafer. The fabrication facilities required for the process are readily available and this process provides the great alternative to existing slow and/or costly nanowire patterning techniques. DA - 2005/7// PY - 2005/7// DO - 10.1016/j.physe.2005.01.010 VL - 28 IS - 2 SP - 107-114 SN - 1873-1759 KW - nanowire KW - nanoimprinting KW - mold KW - template KW - interconnects KW - nanotechnology ER - TY - CHAP TI - Exploiting intra-function correlation with the global history stack AU - Gao, F. AU - Sair, S. T2 - Embedded computer systems: Architectures, modeling, and simulation: 5th international workshop, Samos, Greece, July 18-20, 2005: proceedings (Lecture notes in computer science; 172) CN - Electronic Resource PY - 2005/// VL - 3553 SP - 172-181 PB - Berlin; New York: Springer SN - 354026969X ER - TY - JOUR TI - Electrically programmable photonic crystal slab based on the metal-insulator transition in VO2 AU - Xiao, D. AU - Kim, K. W. AU - Zavada, J. M. T2 - Journal of Applied Physics AB - The possibility of an electrically programmable photonic crystal is investigated theoretically based on the metal-insulator transition of vanadium dioxide (VO2). Recent experiments indicate that this phase transition of the first order can be controlled via external bias and results in significant changes in the electrical and optical properties of VO2. We propose a slab structure based on VO2 whose dielectric properties are modulated periodically in the in-plane direction by selectively inducing phase transition through a lithographically defined array of gate electrodes. A two-dimensional photonic band calculation predicts the presence of a band gap, clearly illustrating the feasibility of the proposed structure. The electrically controlled nature may enable the VO2- based structure to be programmable at a very high speed. DA - 2005/5/15/ PY - 2005/5/15/ DO - 10.1063/1.1898435 VL - 97 IS - 10 SP - 106102 J2 - Journal of Applied Physics LA - en OP - SN - 0021-8979 1089-7550 UR - http://dx.doi.org/10.1063/1.1898435 DB - Crossref ER - TY - JOUR TI - Deposition and plasma measurements of Zr-oxide films with low impurity concentrations by remote PEALD AU - Kim, JY AU - Kim, SH AU - Seo, H AU - Kim, JH AU - Jeon, H T2 - ELECTROCHEMICAL AND SOLID STATE LETTERS AB - Zr-oxide film was deposited by remote plasma-enhanced atomic layer deposition (PEALD) and showed relatively low impurity contamination. In the Zr-oxide film deposition process, the plasma diagnostics were performed to investigate the effects and characteristics of remote plasma. The carbon contents in Zr-oxide film were decreased with increasing rf power. The electron density and optical emission of species were measured using cutoff and optical emission spectroscopy during the deposition. The electron density in remote plasma was about to The dominant emission species of remote plasma was the excited atomic and molecular oxygen. © 2005 The Electrochemical Society. All rights reserved. DA - 2005/// PY - 2005/// DO - 10.1149/1.1854773 VL - 8 IS - 3 SP - G82-G84 SN - 1944-8775 ER - TY - JOUR TI - CAD Flows for Chip-Package CoVerification AU - Varma, A.K. AU - Glaser, A.W. AU - Franzon, Paul T2 - IEEE Transactions on Advanced Packaging AB - A unified method is presented for layout and package design implemented within a commercial design environment that will reduce design time and enable chip-package coverification DA - 2005/// PY - 2005/// DO - 10.1109/TADVP.2004.841475 VL - 28 IS - 1 SP - 194–202 ER - TY - JOUR TI - An Engineered Virus as a Scaffold for Three-Dimensional Self-Assembly on the Nanoscale AU - Blum, Amy Szuchmacher AU - Soto, Carissa M. AU - Wilson, Charmaine D. AU - Brower, Tina L. AU - Pollack, Steven K. AU - Schull, Terence L. AU - Chatterji, Anju AU - Lin, Tianwei AU - Johnson, John E. AU - Amsinck, Christian AU - Franzon, Paul AU - Shashidhar, Ranganathan AU - Ratna, Banahalli R. T2 - Small AB - Exquisite control over positioning nanoscale components on a protein scaffold allows bottom-up self-assembly of nanodevices. Using cowpea mosaic virus, modified to express cysteine residues on the capsid exterior, gold nanoparticles were attached to the viral scaffold to produce specific interparticle distances (see picture). The nanoparticles were then interconnected using thiol-terminated conjugated organic molecules that act as “molecular wires”, resulting in a 3D spherical conductive network, which is only 30 nm in diameter. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2421/2005/z500021_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article. DA - 2005/7// PY - 2005/7// DO - 10.1002/smll.200500021 VL - 1 IS - 7 SP - 702-706 J2 - Small LA - en OP - SN - 1613-6810 1613-6829 UR - http://dx.doi.org/10.1002/smll.200500021 DB - Crossref KW - molecular electronics KW - nanotechnology KW - protein engineering KW - self-assembly KW - viruses ER - TY - JOUR TI - Performance analysis of space-time transmitter diversity techniques for WCDMA using long range prediction AU - Guncavdi, S. AU - Duel-Hallen, Alexandra T2 - IEEE Transactions on Wireless Communications DA - 2005/// PY - 2005/// DO - 10.1109/FWC.2004.840222 VL - 4 IS - 1 SP - 40–45 ER - TY - JOUR TI - A compact large voltage-compliance high output-impedance programmable current source for implantable microstimulators AU - Ghovanloo, M AU - Najafi, K T2 - IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING AB - A new CMOS current source is described for biomedical implantable microstimulator applications, which utilizes MOS transistors in deep triode region as linearized voltage controlled resistors (VCR). The VCR current source achieves large voltage compliance, up to 97% of the supply voltage, while maintaining high output impedance in the 100 MOmega range to keep the stimulus current constant within 1% of the desired value irrespective of the site and tissue impedances. This approach improves stimulation efficiency, extends power supply lifetime, and saves chip area especially when the stimulation current level is high in the milliampere range. A prototype 4-channel microstimulator chip is fabricated in the AMI 1.5-microm, 2-metal, 2-poly, n-well standard CMOS process. With a 5-V supply, each stimulating site driver provides at least 425-V compliance and > 10 MOmega output impedance, while sinking up to 210 microA, and occupies 0.05 mm2 in chip area. A modular 32-site wireless neural stimulation microsystem, utilizing the VCR current source, is under development. DA - 2005/1// PY - 2005/1// DO - 10.1109/TBME.2004.839797 VL - 52 IS - 1 SP - 97-105 SN - 1558-2531 KW - charge balancing KW - CMOS KW - cochlear implant KW - current source KW - implantable microelectronics KW - microstimulation KW - neural prosthesis KW - triode region KW - voltage compliance ER - TY - JOUR TI - Physical and electrical analysis of RuxYy alloys for gate electrode applications AU - Chen, B AU - Suh, Y AU - Lee, J AU - Gurganus, J AU - Misra, V AU - Cabral, C T2 - APPLIED PHYSICS LETTERS AB - Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation Bei Chen, Youseok Suh, Jaehoon Lee, Jason Gurganus, Veena Misra, Cyril Cabral; Physical and electrical analysis of RuxYy alloys for gate electrode applications. Appl. Phys. Lett. 31 January 2005; 86 (5): 053502. https://doi.org/10.1063/1.1857093 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAIP Publishing PortfolioApplied Physics Letters Search Advanced Search |Citation Search DA - 2005/1/31/ PY - 2005/1/31/ DO - 10.1063/1.1857093 VL - 86 IS - 5 SP - SN - 1077-3118 ER - TY - JOUR TI - Bistability in a magnetic and nonmagnetic double-quantum-well structure mediated by the magnetic phase transition AU - Semenov, Y. G. AU - Enaya, H. AU - Kim, K. W. T2 - Applied Physics Letters AB - The hole distribution in a double-quantum-well (QW) structure consisting of a magnetic and a nonmagnetic semiconductor QW is investigated as a function of temperature, the energy shift between the QWs, and other relevant parameters. When the itinerant holes mediate the ferromagnetic ordering, it is shown that a bistable state can be formed through hole redistribution, resulting in a significant change in the properties of the constituting magnetic QW (i.e., the paramagnetic-ferromagnetic transition). The model calculation also indicates a large window in the system parameter space where bistability is possible. Hence, this structure could form the basis of a stable memory element that may be scaled down to a few-hole regime. DA - 2005/// PY - 2005/// DO - 10.1063/1.1864237 VL - 86 IS - 7 SP - 073107 J2 - Appl. Phys. Lett. LA - en OP - SN - 0003-6951 UR - http://dx.doi.org/10.1063/1.1864237 DB - Crossref ER - TY - JOUR TI - Redox-active monolayers on nano-scale silicon electrodes AU - Zhao, Q AU - Luo, Y AU - Surthi, S AU - Li, QL AU - Mathur, G AU - Gowda, S AU - Larson, PR AU - Johnson, MB AU - Misra, V T2 - NANOTECHNOLOGY AB - Uniform arrays of nano-scale electrolyte-molecule-silicon capacitors have been successfully fabricated. This was done by a combination of reactive ion etch and a selective wet etch through an anodic aluminium oxide mask to form nano-holes in silicon oxide/silicon nitride insulator layers on silicon. Self-assembled monolayers of 4-ferrocenylbenzyl alcohol were then attached to the exposed silicon surfaces at the bottom of the nano-holes. Characterization by conventional capacitance and conductance techniques showed very high capacitance and conductance peaks near -0.6 V, that were attributed to the charging and discharging of electrons into and from discrete levels in the monolayer owing to the presence of the redox-active ferrocenes. DA - 2005/2// PY - 2005/2// DO - 10.1088/0957-4484/16/2/013 VL - 16 IS - 2 SP - 257-261 SN - 1361-6528 ER - TY - PAT TI - Power supply systems and methods that can enable an electromagnetic device to ride-through variations in a supply voltage AU - Kelley, A. AU - Ledford, J. AU - Vassalli, L. AU - Cavaroc, J. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Methods and systems for selectively connecting and disconnecting conductors in a fabric AU - Dhawan, A. AU - Ghosh, T. K. AU - Muth, J. AU - Seyam, A. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - JOUR TI - A reconfigurable bandpass filter for RF/microwave multifunctional systems AU - Fathelbab, WM AU - Steer, MB T2 - IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES AB - A network prototype suitable for reconfigurable filters with imaginary-axis transmission zeros is presented. The prototype is synthesized using classical cascade synthesis. Reconfiguration of the transmission zeros is implemented entirely by tunable capacitors. The measured performance of a narrow-band reconfigurable bandpass filter realized in a planar combline using varactor diodes demonstrates the principle. DA - 2005/3// PY - 2005/3// DO - 10.1109/TMTT.2005.843502 VL - 53 IS - 3 SP - 1111-1116 SN - 1557-9670 KW - planar combline filters KW - reconfigurable transmission zeros KW - tunable capacitors ER - TY - JOUR TI - On SAT instance classes and a method for reliable performance experiments with SAT solvers AU - Brglez, F AU - Li, XY AU - Stallmann, MF T2 - ANNALS OF MATHEMATICS AND ARTIFICIAL INTELLIGENCE DA - 2005/1// PY - 2005/1// DO - 10.1007/s10472-005-0417-5 VL - 43 IS - 1-4 SP - 1-34 SN - 1573-7470 KW - satisfiability KW - conjunctive normal form KW - equivalence classes KW - experimental design KW - exponential and heavy-tail distributions KW - reliability function ER - TY - JOUR TI - High Q (Ba, Sr) TiO3 interdigitated capacitors fabricated on low cost polycrystalline alumina substrates with copper metallization AU - Ghosh, D. AU - Laughlin, B. J. AU - Nath, J. AU - Kingon, A. I. AU - Steer, M. B. AU - Maria, J. P. T2 - Ceramic Engineering and Science Proceedings AB - Barium Strontium Titanate (BST) ferroelectric thin films are attractive for radio frequency and microwave applications. However, for many non-military uses, the high cost of conventionally processed devices is a limiting factor. This high cost stems from the use of single-crystalline sapphire, MgO, or LaAlO3 substrates and Pt or Au metallization commonly used. Here we present a device process and materials complement offering a low cost alternative. Planar interdigitated capacitors Ba0.75Sr0.25TiO3 (BST) thin films with chromium/copper top electrodes were fabricated on polycrystalline alumina substrates using a single step photolithographic technique and lift-off. RF magnetron sputtering was used for fabrication of BST thin films while Cu thin films were thermally evaporated The dielectric tunability of the Ba0.75Sr0.25TiO3 IDCs was 40% for an applied electric field of 120 kV/cm, which corresponds to 3 μm electrode gap spacing and a 35 volt dc bias. Low frequency (1MHz) loss measurements reveal a dielectric Q ∼ 100 while a device Q of ∼30 is obtained at 26 GHz. The reduction of Q between 0.1 and 26 GHz can be attributed to the metallization. Leakage current measurements of the BST planar varactors show current densities of 1.0 × 10−6 A/cm2 for an electric field of 100 kV/cm. These dielectric characteristics (tunability and Q value) are comparable to numerous reports of IDCs with BST films prepared on expensive single crystalline substrates using noble metallization. As such, this technology is significantly less expensive, and amenable to large volume manufacturing. DA - 2005/// PY - 2005/// DO - 10.1002/9780470291252.ch13 VL - 26 IS - 5 SP - 125-132 ER - TY - JOUR TI - A tunable combline bandpass filter using Barium Strontium Titanate interdigital varactors on an alumina substrate AU - Nath, J AU - Ghosh, D AU - Fathelbab, W AU - Maria, JP AU - Kingon, AI AU - Franzon, PD AU - Steer, MB T2 - 2005 IEEE MTT-S INTERNATIONAL MICROWAVE SYMPOSIUM, VOLS 1-4 AB - Barium strontium titanate (BST) has a field-dependent permittivity that enables it to be used as a dielectric in a voltage-tunable capacitor or varactor. A tunable combline bandpass filter was designed and characterized using BST varactors fabricated on a polycrystalline alumina substrate with copper metallization and is 14 mm /spl times/ 14 mm in size. The center frequency of the filter varies from 1.6 to 2.0 GHz with the application of 200 V tuning voltage. A 25% tuning range was achieved using tuning field strength of 300 kV/cm. The zero bias insertion loss was 6.6 dB and this decreased to 4.3 dB at the high bias state. The return loss was better than 10 dB. DA - 2005/// PY - 2005/// DO - 10.1109/mwsym.2005.1516670 SP - 595-598 SN - 2576-7216 KW - Barium Strontium Titanate (BST) KW - ferroelectric KW - microstrip filters KW - resonators KW - thin film devices KW - tunable filters KW - varactor ER - TY - JOUR TI - Practical repeater insertion for low power: What repeater library do we need? AU - Liu, X AU - Peng, YT AU - Papaefthyrniou, MC T2 - IEEE TRANSACTIONS ON COMPUTER-AIDED DESIGN OF INTEGRATED CIRCUITS AND SYSTEMS DA - 2005/5// PY - 2005/5// DO - 10.1109/TCAD.2005.855968 VL - 25 IS - 5 SP - 917-924 SN - 1937-4151 KW - interconnect KW - repeater insertion low power ER - TY - JOUR TI - The formation of epitaxial hexagonal boron nitride on nickel substrates AU - Yang, PC AU - Prater, JT AU - Liu, W AU - Glass, JT AU - Davis, RF T2 - JOURNAL OF ELECTRONIC MATERIALS DA - 2005/12// PY - 2005/12// DO - 10.1007/s11664-005-0165-7 VL - 34 IS - 12 SP - 1558-1564 SN - 0361-5235 KW - boron nitride (BN) KW - epitaxial KW - precipitation ER - TY - JOUR TI - Scaling constraints in nanoelectronic random-access memories AU - Amsinck, CJ AU - Di Spigna, NH AU - Nackashi, DP AU - Franzon, PD T2 - NANOTECHNOLOGY AB - Nanoelectronic molecular and magnetic tunnel junction (MTJ) MRAM crossbar memory systems have the potential to present significant area advantages (4 to 6F(2)) compared to CMOS-based systems. The scalability of these conductivity-switched RAM arrays is examined by establishing criteria for correct functionality based on the readout margin. Using a combined circuit theoretical modelling and simulation approach, the impact of both the device and interconnect architecture on the scalability of a conductivity-state memory system is quantified. This establishes criteria showing the conditions and on/off ratios for the large-scale integration of molecular devices, guiding molecular device design. With 10% readout margin on the resistive load, a memory device needs to have an on/off ratio of at least 7 to be integrated into a 64 x 64 array, while an on/off ratio of 43 is necessary to scale the memory to 512 x 512. DA - 2005/10// PY - 2005/10// DO - 10.1088/0957-4484/16/10/047 VL - 16 IS - 10 SP - 2251-2260 SN - 1361-6528 ER - TY - JOUR TI - Performance of the Levenberg–Marquardt neural network training method in electronic nose applications AU - Kermani, Bahram G. AU - Schiffman, Susan S. AU - Nagle, H. Troy T2 - Sensors and Actuators B: Chemical AB - The focus of this study is to find the appropriateness of the Levenberg–Marquardt (LM) neural network (NN) training algorithm for recognition of odor patterns associated with an electronic nose (e-nose). Multiple time-patterns represent step response of the array of sensors to the odorants. The experiments are performed on four representative classes of odorants: coffees, fragrances, hog farm air, and cola beverages. The odor recognition system is composed of a Karhunen–Loéve (KL) based pre-processing unit, and a feedforward neural network with the LM training algorithm. The parameters of the pre-processing unit and the neural network are fine-tuned using a genetic algorithm. Back-propagation algorithm with adaptive learning rate is selected as a standard neural network training method, for the purpose of comparison. The results of the experiments indicate that the LM algorithm provides high correct recognition ratios. In addition, the results confirm that the LM method outperforms the back-propagation (BP) method with adaptive learning rate, for the classes of the odorants provided in this study. DA - 2005/9// PY - 2005/9// DO - 10.1016/j.snb.2005.01.008 VL - 110 IS - 1 SP - 13-22 J2 - Sensors and Actuators B: Chemical LA - en OP - SN - 0925-4005 UR - http://dx.doi.org/10.1016/j.snb.2005.01.008 DB - Crossref KW - genetic algorithms KW - signal processing KW - Levenberg-Marquardt KW - back-propagation KW - feature-extraction KW - data compression KW - sniff KW - smell KW - odor KW - aroma KW - scent KW - fragrance ER - TY - JOUR TI - Moral realism: A defense AU - Mabrito, R. T2 - Philosophical Studies (Dordrecht, Netherlands) DA - 2005/// PY - 2005/// VL - 126 IS - 2 SP - 297-311 ER - TY - JOUR TI - Microcavity light-emitting devices based on colloidal semiconductor nanocrystal quantum dots AU - Xu, J AU - Cui, DH AU - Lewis, BA AU - Wang, AY AU - Xu, SY AU - Gerhold, M T2 - IEEE PHOTONICS TECHNOLOGY LETTERS AB - This letter describes the design, fabrication, and characterization of a microcavity-electroluminescence (EL) device based on colloidal semiconductor nanocrystal quantum dots (NQDs). The device was fabricated by sandwiching a solution-cast film of light-emitting CdSe-CdS core-shell NQDs between two metal mirrors to form a resonant microcavity structure. We have observed a significant reduction in EL emission bandwidth from the fabricated device. Further improvement of the emission efficiency of the NQD-microcavity-EL devices can be achieved upon the minimization of the losses that are pertinent to metal mirrors. DA - 2005/10// PY - 2005/10// DO - 10.1109/LPT.2005.856398 VL - 17 IS - 10 SP - 2008-2010 SN - 1941-0174 KW - electroluminescent devices KW - light sources KW - nanotechnology KW - optoelectronic devices KW - quantum dots ER - TY - JOUR TI - Four-port microwave networks with intrinsic broad-band suppression of common-mode signals AU - Fathelbab, W. M. AU - Steer, M. B. T2 - IEEE Transactions on Microwave Theory and Techniques DA - 2005/// PY - 2005/// DO - 10.1108/TMTT.2005.847046 VL - 53 IS - 5 SP - 1569-1575 ER - TY - JOUR TI - Five-nanometer thick silicon on insulator layer AU - Elmasry, NA AU - Hunter, M AU - ElNaggar, A AU - Bedair, SM T2 - JOURNAL OF APPLIED PHYSICS AB - Silicon on insulator (SOI) has been achieved using epitaxially grown Si∕Y2O3∕Si structure. Silicon film as thin as 5nm was achieved. Pulsed laser deposition technique was used for the epitaxial deposition of both the Y2O3 and silicon. The growth conditions were adjusted to achieve two-dimensional growths of single crystal silicon films on Y2O3. No dislocations were observed in these silicon epitaxial films. This approach will allow the independent thickness control of both silicon and the oxide in the nanometer range. Si∕CeO2∕Si SOI structure was not as successful due to the formation of an amorphous oxide film at the interfaces. DA - 2005/11/15/ PY - 2005/11/15/ DO - 10.1063/1.1803625 VL - 98 IS - 10 SP - SN - 0021-8979 ER - TY - JOUR TI - Enhancing memory-level parallelism via recovery-free value prediction AU - Huiyang AU - Conte, T. M. T2 - IEEE Transactions on Computers AB - The ever-increasing computational power of contemporary microprocessors reduces the execution time spent on arithmetic computations (i.e., the computations not involving slow memory operations such as cache misses) significantly. Therefore, for memory-intensive workloads, it becomes more important to overlap multiple cache misses than to overlap slow memory operations with other computations. In this paper, we propose a novel technique to parallelize sequential cache misses, thereby increasing memory-level parallelism (MLP). Our idea is based on value prediction, which was proposed originally as an instruction-level parallelism (ILP) optimization to break true data dependencies. In this paper, we advocate value prediction in its capability to enhance MLP instead of ILP. We propose using value prediction and value-speculative execution only for prefetching so that not only the complex prediction validation and misprediction recovery mechanisms are avoided, but better performance can also be achieved for memory-intensive workloads. The minor hardware modifications that are required also enable aggressive memory disambiguation for prefetching. The experimental results show that our technique enhances MLP effectively and achieves significant speedups, even with a simple stride value predictor. DA - 2005/// PY - 2005/// DO - 10.1109/tc.2005.117 VL - 54 IS - 7 SP - 897–912 ER - TY - JOUR TI - Electrical characteristics of HfO2 dielectrics with Ru metal gate electrodes AU - Suh, YS AU - Lazar, H AU - Chen, B AU - Lee, JH AU - Misra, V T2 - JOURNAL OF THE ELECTROCHEMICAL SOCIETY AB - Hafnium dioxide, , thin films were prepared by radio frequency magnetron sputtering of thin hafnium layers, followed by an oxidation process. Ru was deposited on the as the gate electrode. An equivalent oxide thickness of 12.5 Å was obtained in metal oxide semiconductor (MOS) capacitor with a low leakage current density of at in accumulation. The work function of Ru gate extracted from capacitance-voltage analysis was 5.02 eV, suggesting Ru has the appropriate work function for p-MOSFETs. Using the conductance method, a high interface state density of from the conduction band edge to the near midgap of Si was obtained in MOS, compared to low interface density level of in poly MOS. To evaluate the thermal stability, the samples were subjected to a rapid thermal anneal in an argon ambient up to 900°C. The electrical characteristics of MOS capacitor are discussed in detail with post-metal annealing temperatures. DA - 2005/// PY - 2005/// DO - 10.1149/1.1992467 VL - 152 IS - 9 SP - F138-F141 SN - 1945-7111 ER - TY - JOUR TI - Effects of heavy boron doping on the valence band offset at the Si1-xGex/Si interface and Si1-xGex band gap AU - Liu, J AU - Ozturk, MC T2 - APPLIED PHYSICS LETTERS AB - Heavily boron-doped Si1−xGex alloys are currently used in recessed source/drain regions of nanoscale metal oxide silicon field effect transistors. Small boron atoms can partially compensate the Si1−xGex strain and change its band gap, which can influence key device parameters such as the junction contact resistance. In this work, the depletion region capacitance of SiGe∕Si heterojunction diodes was measured to determine the valence band offset and the Si1−xGex band gap. The results show that boron doping can have a significant impact on the Si1−xGex band gap and values between those of relaxed and fully strained Si1−xGex alloys can be obtained. DA - 2005/12/19/ PY - 2005/12/19/ DO - 10.1063/1.2149295 VL - 87 IS - 25 SP - SN - 1077-3118 ER - TY - JOUR TI - Complementing software pipelining with software thread integration AU - So, W AU - Dean, AG T2 - ACM SIGPLAN NOTICES AB - Software pipelining is a critical optimization for producing efficient code for VLIW/EPIC and superscalar processors in high-performance embedded applications such as digital signal processing. Software thread integration (STI) can often improve the performance of looping code in cases where software pipelining performs poorly or fails. This paper examines both situations, presenting methods to determine what and when to integrate.We evaluate our methods on C-language image and digital signal processing libraries and synthetic loop kernels. We compile them for a very long instruction word (VLIW) digital signal processor (DSP) -- the Texas Instruments (TI) C64x architecture. Loops which benefit little from software pipelining (SWP-Poor) speed up by 26% (harmonic mean, HM). Loops for which software pipelining fails (SWP-Fail) due to conditionals and calls speed up by 16% (HM). Combining SWP-Good and SWP-Poor loops leads to a speedup of 55% (HM). DA - 2005/7// PY - 2005/7// DO - 10.1145/1070891.1065930 VL - 40 IS - 7 SP - 137-146 SN - 1558-1160 KW - software thread integration KW - software pipelining KW - coarse-grain parallelism KW - stream programming KW - VLIW KW - DSP KW - TI C6000 ER - TY - JOUR TI - Wigner-Poisson model based nano-electronic engineering modeling and design AU - Zhao, P. J. AU - Woolard, D. T2 - Dynamics of Continuous, Discrete & Impulsive Systems. Series B, Applications & Algorithms DA - 2005/// PY - 2005/// VL - 2 SP - 854-859 ER - TY - JOUR TI - Untitled AU - Steer, M T2 - IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES DA - 2005/1// PY - 2005/1// DO - 10.1109/tmtt.2004.839957 VL - 53 IS - 1 SP - 3-3 SN - 0018-9480 ER - TY - JOUR TI - Special issue on blue sky electronic technologies AU - Trew, RJ AU - Woolard, DL T2 - PROCEEDINGS OF THE IEEE DA - 2005/10// PY - 2005/10// DO - 10.1109/JPROC.2005.855454 VL - 93 IS - 10 SP - 1687-1690 SN - 0018-9219 ER - TY - JOUR TI - Sample-sort simulated annealing AU - Thompson, DR AU - Bilbro, GL T2 - IEEE TRANSACTIONS ON SYSTEMS MAN AND CYBERNETICS PART B-CYBERNETICS AB - A simulated annealing (SA) algorithm called Sample-Sort that is artificially extended across an array of samplers is proposed. The sequence of temperatures for a serial SA algorithm is replaced with an array of samplers operating at static temperatures and the single stochastic sampler is replaced with a set of samplers. The set of samplers uses a biased generator to sample the same distribution of a serial SA algorithm to maintain the same convergence property. Sample-Sort was compared to SA by applying both to a set of global optimization problems and found to be comparable if the number of iterations per sampler was sufficient. If the evaluation phase dominates the computational requirements, Sample-Sort could take advantage of parallel processing. DA - 2005/6// PY - 2005/6// DO - 10.1109/TSMCB.2005.843972 VL - 35 IS - 3 SP - 625-632 SN - 1941-0492 KW - optimization methods KW - parallel algorithm KW - simulated annealing (SA) ER - TY - JOUR TI - Microwave AlGaN/GaN HFEVs AU - Trew, RJ AU - Bilbro, GL AU - Kuang, W AU - Liu, Y AU - Yin, H T2 - IEEE MICROWAVE MAGAZINE AB - This article presents the operating physics, performance potential, and status of device development of microwave AlGaN/GaN heterostructure field-effect transistors. AlGaN/GaN HFETs show potential for use in improved RF performance microwave amplifier applications. Development progress has been rapid, and prototype devices have demonstrated RF output power density as high as 30 W/mm. Microwave amplifier output power is rapidly approaching 100 W for single-chip operation, and these devices may soon find application for cellular base station transmitter applications. Devices are being developed for use in X-band radars, and RF performance is rapidly improving. The HFET devices experience several physical effects that can limit performance. These effects consist of nonlinearities introduced during the high-current and high-voltage portions of the RF cycle. High-current phenomena involve the operation of the conducting channel above the critical current density for initiation of space-charge effects. The source resistance is modulated in magnitude by the channel current, and high source resistance results. High voltage effects include reverse leakage of the gate electrode and subsequent charge trapping effects on the semiconductor surface, and RF breakdown in the conducting channel. These effects can produce premature saturation effects. Also, under certain conditions, high voltage operation of the device can initiate an IMPATT mode of operation. When this occurs, the channel current increases and RF gain is increased. This phenomenon enhances the RF output power of the device. The physical limiting effects can be controlled with proper design, and the outlook for use of these devices in practical applications is excellent. DA - 2005/3// PY - 2005/3// DO - 10.1109/MMW.2005.1417998 VL - 6 IS - 1 SP - 56-66 SN - 1527-3342 ER - TY - JOUR TI - HyPE: Hybrid power estimation for IP-based systems-on-chip AU - Liu, X AU - Papaefthymiou, MC T2 - IEEE TRANSACTIONS ON COMPUTER-AIDED DESIGN OF INTEGRATED CIRCUITS AND SYSTEMS AB - In this paper, we present a novel power estimation scheme for programmable systems consisting of predesigned datapath and memory components. The proposed hybrid methodology yields highly accurate estimates within short runtimes by combining high-level simulation with analytical macromodeling of circuit characteristics. The kernel of our methodology is a simulation-free power estimation scheme for memoryless datapaths comprising several IP blocks connected in fixed topologies. The outer shell of our hybrid scheme is a functional simulation, which is performed only on the interfaces between memoryless components and memory blocks. This simulation accurately captures the control signals that affect the flow of data and, consequently, the utilization and power dissipation of hardware. Experimental results validate the accuracy and efficiency of our methodology. We applied our static power estimation kernel to signal processing and data encryption datapaths. For designs of up to 576 IP blocks, the average error of our power estimates is 7.3% in comparison with switch-level simulation results. We implemented our hybrid scheme into a power estimation tool, called HYPE, and used it to explore various architectural alternatives in the design of a 256-state Viterbi decoder and a Rijndael encryptor. For designs with about 1 million transistors, our estimator terminates within seconds. Compared with commercial state-of-the-art gate-level power estimators, our proposed methodology is up to 1000 times faster with 5.4% deviation on average. DA - 2005/7// PY - 2005/7// DO - 10.1109/TCAD.2005.850891 VL - 24 IS - 7 SP - 1089-1103 SN - 1937-4151 KW - design automation KW - optimization KW - power model KW - signal statistics ER - TY - JOUR TI - High-frequency solid-state electronic devices AU - Trew, RJ T2 - IEEE TRANSACTIONS ON ELECTRON DEVICES AB - Starting with exploratory work in the 1930s and development work in the 1940s a variety of two-terminal and three-terminal solid-state device structures have been proposed, fabricated, and developed. This work parallels the development effort on vacuum electronic devices, and the two technologies share many applications. The solid-state and vacuum electronic devices work in tandem to enable numerous commercial and military systems. Solid-state device development is closely linked to semiconductor materials growth and processing technology, and advances such as the introduction of heterojunction growth technology, permit complex multiple layer device structures to be fabricated and optimized for maximized device performance. This work has been very successful and a variety of high-performance diodes and transistors are now available for use from UHF into the millimeter-wave spectrum, approaching terahertz frequencies. The development, operating principles, and state-of-the-art of various diode and transistor structures are reviewed. DA - 2005/5// PY - 2005/5// DO - 10.1109/TED.2005.845862 VL - 52 IS - 5 SP - 638-649 SN - 0018-9383 KW - microwave solid-state amplifiers KW - microwave solid-state devices ER - TY - JOUR TI - Editorial - State of this TRANSACTIONS AU - Steer, MB T2 - IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES DA - 2005/4// PY - 2005/4// DO - 10.1109/TMTT.2005.845776 VL - 53 IS - 4 SP - 1121-1123 SN - 1557-9670 ER - TY - JOUR TI - A low-power multirate differential PSK receiver for space applications AU - Yuce, MR AU - Liu, WT T2 - IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY AB - Wireless communication for deep-space and satellite applications needs to accommodate the Doppler shift caused by the movement of the space vehicle and should consume low power to conserve the onboard power. A low-power phase-shift keying (PSK) receiver has been designed for such applications. The receiver employs double differential detection to be robust against Doppler shift and uses subsampling with a 1-bit A/D converter and digital decimation architecture at the front end to achieve low-power consumption. The receiver is also designed to be programmable to operate using single-stage differential detection instead of double-stage differential detection at low Doppler rates to obtain optimum performance. Furthermore, the baseband can be employed in either direct subsampling or intermediate frequency (IF)-sampling front ends. Both front ends offer minimal power consumption and differ from traditional types by replacing some conventional analog components such as a voltage-controlled oscillator, mixer, or phase-locked loop with their digital counterparts. This eliminates problems due to dc offset, dc voltage drifts, and low-frequency (LF) noise. The paper also includes a brief discussion of the nonidealities existing in real applications. The proposed phase shift keying (PSK) receiver supports a wide range of data rates from 0.1-100 Kbps and has been implemented in a CMOS process. DA - 2005/11// PY - 2005/11// DO - 10.1109/TVT.2005.858196 VL - 54 IS - 6 SP - 2074-2084 SN - 1939-9359 KW - differential detection KW - phase-shift keying (PSK) KW - space communications KW - subsampling ER - TY - JOUR TI - A study of robust Active Queue Management schemes for correlated traffic AU - Oruganti, S. S. AU - Devetsikiotis, M. T2 - Computer Communications DA - 2005/// PY - 2005/// VL - 28 IS - 1 SP - 11- ER - TY - JOUR TI - Load estimation for load monitoring at distribution substations AU - Baran, ME AU - Freeman, LAA AU - Hanson, F AU - Ayers, V T2 - IEEE TRANSACTIONS ON POWER SYSTEMS AB - This paper addresses the issues related to the real-time monitoring of loads at distribution substations. A method is proposed for estimating the measurements that become unavailable due to metering problems. To address the low redundancy associated with the load monitoring scheme, the method uses a regression-based model and makes use of the strong correlation between the loads that are geographically close to each other. The method was tested with actual field data. The results indicate that the method has the acceptable performance for measurement loss of up to a week. The average estimation error varies 2-7.5%, depending on which measurement is lost and how up-to-date the historical data is. DA - 2005/2// PY - 2005/2// DO - 10.1109/TPWRS.2004.840409 VL - 20 IS - 1 SP - 164-170 SN - 0885-8950 KW - load estimation KW - power distribution KW - power system monitoring ER - TY - JOUR TI - Electrical package impact on VCSEL-based optical interconnects AU - Pant, R AU - Neifeld, MA AU - Steer, MB AU - Kanj, H AU - Cangellaris, A T2 - OPTICS COMMUNICATIONS AB - A new CAD tool fREEDA® based on state variable approach and universal error concept is presented for modelling and simulating systems where physical domains such as electrical, thermal, and optical interact with each other. A single implementation of device equations in fREEDA® can be used with different analysis types such as transient and harmonic balance, etc. To demonstrate the multi-physics capabilities of fREEDA®, we present a study of the impact of electrical packages on the source module performance in multi-gigabit per second vertical cavity surface emitting laser (VCSEL)-based optical interconnects. The effect of various operating conditions such as bias/drive level and driver configuration are studied. We consider electrical packages such as printed wire board, thin-film and flip-chip in our study. A comparison of VCSELs with stripe lasers is also presented. DA - 2005/1/17/ PY - 2005/1/17/ DO - 10.1016/j.optcom.2004.10.017 VL - 245 IS - 1-6 SP - 315-332 SN - 1873-0310 KW - optical interconnects KW - VCSELs KW - simulation KW - packaging ER -