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Annual International Conference of the IEEE engineering in Medicine and Biology Society

作者： Hubert de Bruin Gary Hasey Julie Hemily Electrical and Computer Engineering Department McMaster University Department of Psychiatry and Behavioual Neurosciences McMaster University Electrical and Biomedical Engineering Program McMaster University

ISBN: (纸本)9781424441211

This paper presents the preliminary results of a study to determine dorsolateral prefrontal cortex sensitivity to rTMS stimulation presented at clinically accepted amplitudes, frequencies and locations. A specially developed EEG system with 10-20 electrode locations was used to record the short latency magnetically evoked potentials. Sixteen normal subjects were stimulated using 10 Hz for the left hemisphere and 1 Hz for the right. The evoked potentials recorded for left sided stimulation were significantly larger than for the right sided stimulation. Further, the stimulation energies, though within the range used clinically for the treatment of depression were insufficient to excite evoked potentials in several subjects.

关键词： Evoked potentials RTMS Stimulus cortical sensitivity Transcranial magnetic stimulation

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High Performance High Dielectric Constant Films Deposited by Dual Spectral Source Rapid Isothermal Assisted Metalorganic Chemical Vapor Deposition (MOCVD)

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MRS Online Proceedings Library (OPL) 2011年第1期470卷 133-133页

作者： Y. Chen R. Singh S. DeBoer R.P.S. Thakur Department of Electrical and Computer Engineering Clemson University Clemson SC 29634 Department of Electrical and Computer Engineering and Material Science and Engineering Program Clemson University Clemson SC 29634 singh@ces.clemson.edu Micron Technology Inc. Boise ID 83706

Dual spectral source assisted MOCVD is an ideal technique for the deposition of high dielectric constant materials as well as other electronic and optical materials. Tungsten halogen lamps and a deuterium lamp are used as the sources of optical and thermal energy. Ta2O5 films were deposited at 200°C for 30 minutes and annealed at 600°C for 30 minutes have shown leakage current densities as low as 10−10 A/ cm2 for gate voltage under 5V. To the best of our knowledge, these are the best results reported to date by other researchers. The high energy photons used in the in-situ cleaning and deposition process play an important role in obtaining high quality films of Ta2O5.

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Spatio-temporal measurement and model for number of occupied channels

Spatio-temporal measurement and model for number of occupied...

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International Conference on Telecommunications (ICT)

作者： Khalid A. Qaraqe Nariman Rahimian Hasari Celebi Costas N. Georghiades Electrical and Computer Engineering Program Texas A and M University Doha Qatar Department of Electrical and Computer Engineering Texas A and M University College Station TX USA

Cognitive Radio (CR) systems are a promising solution to the spectrum scarcity problem. However, accurate modeling of spectrum utilization is essential to obtain a better quantitative understanding of important concepts of CR systems. Compact mathematical formulations that describe the realistic spectrum usage would improve the recent theoretical work to a large extent. The data generated from such models would also increase the quality of the simulation based research in the aspect of realism. Besides, in practice, measurement campaigns would prefer if they could characterize results with a few well known parameters instead of exchanging large amount of data. Therefore, in this paper we try to come up with a mathematical model for the spectrum usage by estimating the Probability Mass Function (PMF) of the number of occupied channels. Note that this also gives an insight regarding the spectrum availability. To do this, the data collected from a spectrum occupancy measurement campaign conducted in the State of Qatar is used. The measurements are performed over three consecutive days considering 700-3000 MHz frequency band at four different locations concurrently. We show that after applying the Chi square test, the Log-Normal distribution fits the best among other candidates to the empirical PMF independent of location and the threshold used to define a channel as occupied.

关键词： Nakagami distribution Mathematical model Bandwidth Time frequency analysis Cognitive radio Log-normal distribution

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Modification of Visible Light Emission from Silicon Nanocrystals as a Function of Size, Electronic Structure, and Surface Passivation

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MRS Online Proceedings Library 2011年第1期536卷 185-190页

作者： M. V. Wolkin J. Jorne P. M. Fauchet G. Allan C. Delerue Materials Science Program Department of Chemical Engineering University of Rochester Rochester USA Department of Electrical and Computer Engineering University of Rochester Rochester USA IEMN-ISEN Lille France

The effect of surface passivation and crystallite size on the photoluminescence of porous silicon is reported. Oxygen-free porous silicon samples with medium to ultra high porosities have been prepared by using electrochemical etching followed by photoassisted stain etching. As long as the samples were hydrogen-passivated the PL could be tuned from the red (750nm) to the blue (400nm) by increasing the porosity. We show that when surface oxidation occurred, the photoluminescence was red-shifted. For sizes smaller than 2.8nm, the red shift can be as large as 1eV but for larger sizes no shift has been observed. Comparing the experimental results with theoretical calculations, we suggest that the decrease in PL energy upon exposure to oxygen is related to recombination involving an electron or an exciton trapped in Si=O double bonds. This result clarifies the recombination mechanisms in porous silicon.

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Effects of SMES on Dynamic Behaviors of Type D-Wind Turbine Generator-Grid Connected during Short Circuit

Effects of SMES on Dynamic Behaviors of Type D-Wind Turbine ...

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IEEE Power and Energy Society General Meeting

作者： A. M. Shiddiq Yunus A. Abu-Siada M. A. S. Masoum Department of Mechanical Engineering Energy Conversion Study Program State Polytechnic of Ujungpandang Department of Electrical and Computer Engineering Curtin University

ISBN: (纸本)9781457710001

Application of Superconducting Magnetic Energy Storage unit with Hysteresis Current Control-Fuzzy Logic to improve the performance of Wind Turbine Generator-Grid connected during short circuit is presented. Five 2 MW Type D-Wind Turbine Generator connected to a grid is simulated using SIMULINK/MATLAB program. The Superconducting Magnetic Energy Storage unit consists of a Voltage Source Converter and DC-DC Chopper that are controlled by Hysteresis Current Control and Fuzzy Logic Controller respectively. Simulation results show that the proposed control algorithm of Superconducting Magnetic Energy Storage unit is effective in saving some MWs of Type D-Wind Turbine Generator production during occurrence of short circuit in the line.

关键词： Fuzzy Logic Hysteresis Current Control Superconducting magnetic energy storage Type D-Wind Turbine Generator SUPERCONDUCTING MAGNETIC ENERGY STORAGE Fuzzy logic Wind Generators Short circuits voltage source converter turbogenerators computer algorithms fuzzy logic controller

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On the interference due to cooperative cognitive radios in the presence of multiple low-power primary users

On the interference due to cooperative cognitive radios in t...

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Annual Allerton Conference on Communication, Control, and Computing

作者： Prasanna Madhusudhanan Timothy X Brown Youjian Liu Department of Electrical Computer and Energy Engineering University of Colorado Boulder CO USA Department of Electrical Computer and Energy Engineering Interdisciplinary Telecommunications Program University of Colorado Boulder CO USA

ISBN: (纸本)9781457718175

We analyze a cognitive radio network where the low-power primary users and cognitive radio (CR) devices are distributed according to two independent homogeneous Poisson processes over the k- dimensional space, where k = 1, 2, 3. The CRs cooperate among themselves in detecting the beacons transmitted by the primary users, to ensure that they cause reduced interference at the primary users. A range of cooperative sensing schemes including the no (NC), partial (PC) and full cooperation (FC) scenarios are analyzed. Using the concepts of stochastic geometry, we assess the impact of the presence of the multiple primary users on the distribution of the signal-to-interference-plus-noise ratio (SINR) at a given primary user, for each cooperation scheme. Further, we characterize the improvement in the spectrum usage due to the CR operation in the licensed frequency band in terms of the probability, denoted by rho, that a CR is able to operate within the k-dimensional space. Using our calculations of the SINR at the primary user and rho, it is shown that the PC scheme achieves enhanced spectrum usage vis-a-vis the FC scheme and an improved SINR as compared to the NC scheme. Moreover, the PC scheme can be tuned in such a way that any desired value for spectrum usage and SINR is achievable.

关键词： Interference Receivers PSNR Silicon Cognitive radio Random variables

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Structural Characterization of Nc-Si/A-Sio 2 Superlattices Subjected To Thermal Treatment

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MRS Online Proceedings Library 2011年第1期536卷 141-146页

作者： G. F. Grom L. Tsybeskov K. D. Hirschman P. M. Fauchet J. P. McCaffrey H. J. Labbé D. J. Lockwood Department of Mechanical Engineering Materials Science Program USA Department of Electrical and Computer Engineering University of Rochester Rochester USA Institute for Microstructural Sciences National Research Council Ottawa Canada

The morphology of nanocrystalline (nc)-Si/amorphous (a)-SiO2 superlattices (SLs) is studied using Raman spectroscopy in the acoustic and optical phonon ranges, transmission electron microscopy (TEM), and atomic force microscopy (AFM). It is demonstrated that high temperature annealing (up to 1100°C) and oxidation in O2/H2O ambient do not destroy the SL structure, which retains its original periodicity and nc-Si/a-SiO2 interface abruptness. It is found that oxidation at high temperatures reduces the defect density in nc-Si/a-SiO2 SLs and induces the lateral coalescence of Si nanocrystals (NCs). The size, shape, packing density, and crystallographic orientation of the Si nanocrystals are studied as a function of the oxidation time.

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Multiuser Hybrid Switched-Selection Diversity Systems

Multiuser Hybrid Switched-Selection Diversity Systems

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IEEE International Symposium on Personal, Indoor and Mobile Radio Communications

作者： Mohammad Shaqfeh Hussein Alnuweiri Mohamed-Slim Alouini Department of Electrical and Computer Engineering Texas A&M University in Qatar Electrical Engineering Program King Abdullah University of Science and Technology (KAUST)

ISBN: (纸本)9781457713460

A new multiuser scheduling scheme is proposed and analyzed in this paper. The proposed system combines features of conventional full-feedback selection-based diversity systems and reduced-feedback switch-based diversity systems. The new hybrid system provides flexibility in trading-off the channel information feedback overhead with the prospected multiuser diversity gains. The users are clustered into groups, and the users' groups are ordered into a sequence. Per-group feedback thresholds are used and optimized to maximize the system overall achievable rate. The proposed hybrid system applies switched diversity criterion to choose one of the groups, and a selection criterion to decide the user to be scheduled from the chosen group. Numerical results demonstrate that the system capacity increases as the number of users per group increases, but at the cost of more required feedback messages.

关键词： Multiuser scheduling Reduced feedback Hybrid switched-selection diversity

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Metamorphic solar cells employing chemical mechanical polishing and MOVPE regrowth

Metamorphic solar cells employing chemical mechanical polish...

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37th IEEE Photovoltaic Specialists Conference, PVSC 2011

作者： Mawst, L.J. Dudley, P. Kirch, J. Kim, T. Ruder, S. Kuech, T.F. Tatavarti, R. Department of Electrical and Computer Engineering University of Wisconsin - Madison 1415 Engineering Dr. Madison WI 53706 United States Materials Science Program University of Wisconsin - Madison 1415 Engineering Dr. Madison WI 53706 United States Department of Chemical and Biological Engineering University of Wisconsin - Madison 1415 Engineering Dr. Madison WI 53706 United States MicroLink Devices Inc. Niles IL United States

ISBN: (纸本)9781424499656

We have investigated the MOVPE growth of InxGa1-xAs metamorphic buffer layer (MBL) structures with a focus on techniques to improve the surface morphology and determine the influence of morphology on subsequently grown single-junction device structures. To improve the surface roughness of the underlying MBL, Chemical-Mechanical Polishing (CMP) is employed and MOVPE regrowth of single-junction (SJ) solar cells on top of the polished surface is performed. AFM image analysis indicates the CMP process is effective in reducing the step-graded InxGa1-xAs MBL surface roughness from ∼7-10 nm (as-grown) to 2.3 nm post CMP. A post-CMP ozone/HF treatment was found to be effective in removing silica residue remaining on the surface from the CMP process, allowing for the growth of films on top of the MBL surface subjected to CMP. Improved short circuit current density (Jsc) and external quantum efficiency (QE) were obtained from SJ (1eV) devices which employ the CMP process compared with those on as-grown MBLs. © 2011 IEEE.

关键词： Chemical mechanical polishing

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A LOW-POWER IMPLANTABLE NEUROPROCESSOR ON NANO-FPGA FOR BRAIN MACHINE INTERFACE APPLICATIONS

A LOW-POWER IMPLANTABLE NEUROPROCESSOR ON NANO-FPGA FOR BRAI...

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IEEE International Conference on Acoustics, Speech and Signal Processing

作者： Fei Zhang Mehdi Aghagolzadeh Karim Oweiss Department of Electrical and Computer Engineering Michigan State University East Lansing MI USA Department of Electrical and Computer Engineering and Neuroscience Program Michigan State University East Lansing MI USA

This paper presents the implementation of a low-power and implantable neuroprocessor on low-cost nano-FPGA for data reduction and on-the-fly spike sorting in Brain Machine Interface applications. Detailed analysis of efficient utilization of the hardware resources, power consumption and design scalability are provided. The prototype we report here enables simultaneous processing of 32-channel data sampled at 25 kHz/channel with 8-bit/sample resolution with less than 5 mW power consumption for all modes of operation (monitoring, compression and sensing) at 1.2 V core voltage supply on a 5 mm X 5 mm nano-FPGA.

关键词： Feature extraction Field program.able gate arrays Sorting Wireless communication Discrete wavelet transforms Power demand Clocks

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