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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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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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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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Theoretical and Experimental Study of Barium Zinc-Cadmium Tantalate-based Microwave Dielectrics

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MRS Online Proceedings Library (OPL) 2011年第1期783卷 B4.7-B4.7页

作者： Shaojun Liu Mark Van Schilfgaarde Jian Sun Louisa Badd David Smith Novak S. Petrovixc R. Taylor N. Newman Chemical and Materials Engineering Department Science and Engineering of Materials Program Center for Solid State Science Arizona State University Tempe AZ 85287–6006 Electrical and Computer Engineering Department Queens land University Paddington Australia 4064

Single-phase Ba(Cd1/3Ta2/3)O3 ceramics have been produced using conventional powder processing methods. In our initial investigations, 2wt% ZnO powder was added to act as a sintering aid since a high-density ceramic was not formed from solid-state diffusion alone. The resulting Ba(Cd0.327Zn0.006Ta2/3)O3 material sintered at 1550° C exhibits a dielectric constant of ∼33 and loss tangent of <5×10−5 at 2 GHz. In our more recent work, we have used boron as a sintering aid to facilitate sintering at temperatures as low as 1300° C, enhance the structural quality and improve the microwave properties of Ba(Cd1/3Ta2/3)O3 dielectrics. TEM results indicate that the liquid sintering mechanism is an important factor for boron concentrations exceeding 0.5wt%, while a point defect mechanism plays the dominant role at lower boron concentrations. The presence of superstructure peaks and splitting of the (220) and (214) peaks in X-ray diffraction spectra are direct evidence for the distortion from cubic symmetry as a result of Cd and Ta ordering on the ***-initio electronic structure calculations within the local density functional approximation have been used to give insight into the unusual properties of this class of materials. In both Ba(Zn1/3Ta2/3)O3 and Ba(Cd/3Ta2/3)O3, the conduction band maximum and valence band minimum are composed of mostly weakly itinerant Ta 5d-and Zn-3d/Cd-4d levels, respectively. The covalent nature of the directional d-electron bonding in these high-Z oxides plays an important role in producing a more rigid lattice with higher melting points and enhanced phonon energies, and possibly inherently lower intrinsic microwave loss than comparable ionic materials.

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Digital library 2.0 for educational resources

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Lecture Notes in computer science

作者： Akbar, Monika Fan, Weiguo Shaffer, Clifford A. Chen, Yinlin Cassel, Lillian Delcambre, Lois Garcia, Daniel D. Hislop, Gregory W. Shipman, Frank Furuta, Richard Carpenter II, B. Stephen Hsieh, Haowei Siegfried, Bob Fox, Edward A. Department of Computer Science Virginia Tech. Blacksburg VA United States Department of Computing Sciences Villanova University Villanova PA United States Department of Computer Science Portland State University Portland OR United States Electrical Engineering and Computer Science UC Berkeley Berkeley CA United States Department of Computer Science Drexel University Philadelphia PA United States Department of Computer Science Texas A and M College Station TX United States Art Education Program Pennsylvania State University State College PA United States School of Library and Information Science Univ. of Iowa Iowa City IA United States

ISBN: (纸本)9783642244681

We report on focus group feedback regarding the services provided by existing education-related Digital Libraries (DL). Participants provided insight into how they seek educational resources online, and what they perceive to be the shortcomings of existing educational DLs. Along with useful content, social interactions were viewed as important supplements for educational DLs. Such interactions lead to both an online community and new forms of content such as reviews and ratings. Based on our analysis of the focus group feedback, we propose DL 2.0, the next generation of digital library, which integrates social knowledge with DL content. © 2011 Springer-Verlag.

关键词： Digital libraries

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Design of interval type-2 fuzzy logic controllers for flocking algorithm

Design of interval type-2 fuzzy logic controllers for flocki...

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IEEE International Conference on Fuzzy Systems (FUZZ-IEEE)

作者： Seung-Mok Lee Jong-Hwan Kim Hyun Myung Department of Civil and Environmental Engineering Robotics Program KAIST Daejeon South Korea Department of Electrical Engineering and Computer Science Robotics Program KAIST Daejeon South Korea

This paper presents a novel interval type-2 fuzzy logic control architecture for flocking system when the system has noisy sensor measurements. The traditional type-1 fuzzy logic controller (FLC) using precise type-1 fuzzy sets cannot fully model and handle the uncertainties of sensor data. However, type-2 FLC using type-2 fuzzy sets with a footprint of uncertainty (FOU) produces better performances under noisy environments. In this paper, therefore, we present a reactive control architecture for flocking algorithm that is based on interval type 2 FLC to implement the flocking behaviors consisting separation, obstacle avoidance, and velocity matching behaviors. The type-2 based control system could cope with the uncertainties of noisy sensor measurements and resulted in good performances that outperformed the type-1 FLC.

关键词： Collision avoidance Robot sensing systems Trajectory Fuzzy sets Fuzzy logic Noise measurement

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A transfer method for complex structures fabricated on non-planar surfaces

A transfer method for complex structures fabricated on non-p...

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International Solid-State Sensors, Actuators and Microsystems Conference

作者： Zeng, X. Huang, C.-C. Jiang, H. Department of Electrical and Computer Engineering University of Wisconsin Madison Madison WI United States Eye Research Institute University of Wisconsin - Madison Madison WI United States Materials Science Program University of Wisconsin - Madison Madison WI United States

ISBN: (纸本)9781457701573

A method to fabricate complex structures on non-planar surfaces by utilizing a transfer method is presented. 3-dimensional and high-aspect-ratio microelectromechanical systems (MEMS) structures are transferred to flexible membranes, and can be further transferred to any non-planar surfaces. Here, we used a structure formed on a silicon-on-insulator (SOI) wafer by deep reactive-ion etching (DRIE) as an example. Both photoresist SU8-2050 and AZ 4620 were used as the flexible membranes. The effect of the structure and density of pillars on the transferring procedure was studied. Potentially this method could be utilized to transfer any MEMS structures and devices to any non-planar surfaces, thus possessing great potential in MEMS devices. © 2011 IEEE.

关键词： Photoresists

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Capacitance Humidity Sensor

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MRS Online Proceedings Library 2011年第1期382卷 469-475页

作者： Andrew R. K. Ralston Paul E. Thoma Carl F. Klein Denice D. Denton Materials Science Program Department of Electrical and Computer Engineering and Department of Chemistry University of Wisconsin-Madison Madison USA Central Research Johnson Controls Inc. Milwaukee USA

A capacitance relative humidity (RH) sensor is described that has a design, construction, and material composition that result in an inexpensive and robust sensor. This sensor has a multilayer, free-standing film construction. It consists of a humidity sensitive polyimide (PI) dielectric core and conductive layers consisting of carbon filled polysulfone on each side of the polyirnide film to form a capacitor. The polyimide used is a BPDA-ODA type, and replaces a PMDA-ODA type polyimide used in a previous version of this sensor. The BPDA-ODA sensor has a nominal capacitance of 200 pF and a nominal sensitivity of 13% at 100% RH. The characteristics of this humidity sensor are discussed and compared to the characteristics of the PMDA-ODA type sensor. Characteristics considered include the PI film moisture uptake and water vapor transmission, and the sensors’ sensitivity to relative humidity, frequency response, and aging at 85°C/85% RH. The dual-state sorption model and free volume calculations are used to demonstrate that observed differences in the film are due to differences in chemical composition between the films.

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Microfluidic actuators based on infrared-light responsive PNIPAAm hydrogel nanocomposite incorporating graphene-oxide

Microfluidic actuators based on infrared-light responsive PN...

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International Solid-State Sensors, Actuators and Microsystems Conference

作者： Lo, Chi-Wei Zhu, Difeng Jiang, Hongrui Materials Science Program University of Wisconsin-Madison WI 53706 United States Department of Electrical and Computer Engineering University of Wisconsin-Madison WI 53706 United States Eye Research Institute University of Wisconsin Madison Madison WI 53706 United States

ISBN: (纸本)9781457701573

In lab-on-a-chip systems, microactuators are critical to control the flow within the microchannels. Most of the current actuators require hardware connection (electromagnetic, thermopneumatic actuators, etc.) within the channels, thus significantly increasing the system complexity. Remotely controllable actuators would greatly simplify the system. We demonstrate nanocomposite microfluidic actuators remotely controlled by infrared (IR) light. These actuators are fabricated out of thermo-responsive poly-N- isopropylacrylamide (PNIPAAm) nanocomposite hydrogels incorporated with glycidyl methacylate functionalized graphene-oxide (GO-GMA). Two example devices were realized implementing such actuators: a microvalve and a tunable liquid microlens. © 2011 IEEE.

关键词： Hydrogels

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On the ergodic secrecy capacity of the wiretap channel under imperfect main channel estimation

On the ergodic secrecy capacity of the wiretap channel under...

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Asilomar Conference on Signals, Systems & computers

作者： Zouheir Rezki Ashish Khisti Mohamed-Slim Alouini Electrical Engineering Program Physical Science and Engineering Division King Abdullah University for Science and Technology Thuwal Makkah Saudi Arabia Electrical and Computer Engineering Department University of Toronto Toronto ONT Canada

ISBN: (纸本)9781467303217

The ergodic secrecy capacity of the wiretap channel is known when the main channel (between the transmitter and the legitimate receiver) state information (CSI) is perfect at the transmitter and the coherence period is sufficiently large to enable random coding arguments in each block. In a fast fading scenario, when the codeword length spans many coherence periods, the secrecy capacity is still not known. In this paper, we present a framework that characterizes this secrecy capacity under imperfect main channel estimation at the transmitter. Inner and outer bounds on the ergodic secrecy capacity are derived for a class of independent identically distributed (i.i.d.) fading channels. The achievable rate is a simple on-off scheme using a Gaussian input. The upper bound is obtained using an appropriate correlation scheme of the main and the eavesdropper channels. The upper and the lower bounds coincide with recently derived ones in the perfect main CSI extreme. Furthermore, the lower bound matches the upper bound in no main CSI extreme, where the secrecy capacity is equal to zero. Numerical results are provided for independent identically distributed (i.i.d.) Rayleigh fading channels.

关键词： Integrated circuits Channel estimation Signal to noise ratio Cryptography Antennas

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