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Theoretical Modeling and Improved Thermoelectric Properties in (111) and (001) Oriented PbTe/Pb 1-x Eu x Te MQWs

MRS Online Proceedings Library 1997年第1期490卷 263-268页

作者： T. Koga S. B. Cronin T. C. Harman X. Sun M. S. Dresselhaus Division of Engineering and Applied Sciences Harvard University Cambridge Department of Physics Massachusetts Institute of Technology Cambridge Lincoln Laboratory Massachusetts Institute of Technology Lexington Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge

Theoretical modeling of ZT of (111) and (001) oriented PbTe/Pb1-xEuxTe multiple-quantum-wells (MQWs) is carried out assuming parabolic energy bands and the constant relaxation time approximation. The model calculation for the (111) oriented MQWs is compared with the recently obtained experimental results for the Seebeck coefficient and the Hall carrier concentration. The thermoelectric properties for (001) oriented PbTe MQWs are expected to have even better thermoelectric properties than the (111) oriented PbTe MQWs.

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Prospects for High Thermoelectric Figures of Merit in 2D Systems

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MRS Online Proceedings Library 1997年第1期478卷 55-66页

作者： M. S. Dresselhaus X. Sun S. B. Cronin T. Koga G. Dresselhaus K. L. Wang Department of Physics Massachusetts Institute of Technology Cambridge USA Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge Division of Engineering and Applied Sciences Harvard University Cambridge USA Francis Bitter Magnet Lab. Massachusetts Institute of Technology Cambridge USA Department of Electrical Engineering University of California Los Angeles USA

Enhanced ZT has been predicted theoretically and observed experimentally in 2D quantum wells, with good agreement between theory and experiment. Advantages of low dimensional systems for thermoelectric applications ar...

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Fault-tolerant replication in networks with asynchronous communication link failures

Fault-tolerant replication in networks with asynchronous com...

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IEEE International Conference on Performance, Computing and Communications (IPCCC)

作者： D.M. Lazoff A.B. Stephens Applied Physics Laboratory Johns Hopkins University Laurel MD USA Department of Computer Science and Electrical Engineering University of Maryland Baltimore County Baltimore MD USA

We investigate the problem of locating data replicas in a network in order to maximize data availability. In particular, we analyze the complexity of computing optimal placements in networks in which communication link failures are asynchronous (i.e., only a single link fails at a time.) We show that placements maximizing availability for read operations minimize the status of the subtree induced by the data copies in the network component tree. It is observed that the optimal placement problem for read operations corresponds to two network optimization problems that have previously been studied, and thus existing polynomial algorithms for these problems can be used to compute optimal placements efficiently. We then present new results for the problem of determining optimal placements for write operations. It is shown that this problem can be formulated as a packing optimization problem, and that this problem is NP-complete.

关键词： Fault tolerance Intelligent networks Polynomials Access protocols computer networks Asynchronous communication physics Laboratories Failure analysis Availability

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Time-frequency analysis with eight-figure kernel

Time-frequency analysis with eight-figure kernel

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

作者： Y. Noguchi K. Watanabe E. Kashiwagi T. Hamada K. Mariko F. Matsumoto S. Sugimoto Department of Applied Physics National Defense Academy Yokosuka Japan Department of Computer Science National Defense Academy Yokosuka Japan Faculty of Electrical Engineering Shonan Institute of Technology Fujisawa Japan

Time-Frequency (TF) analyses have been widely used to analyze some nonstationary signals like speech and biological signals. Cohen's class TF distribution has a high resolution in time and frequency and becomes a powerful tool for nonstationary signal analysis. In order to apply the TF analysis using a novel kernel to biological signals, the authors investigated a higher resolution kernel for the ultrasound Doppler signal. The authors would like to apply the TF analysis to blood flow signal analysis. They measured the ultrasound Doppler signal which was obtained in olive oil with a steel ball moving to and fro in the continuous ultrasound. The movement of the steel ball was controlled by various functions. The authors used three kinds of kernel: (1) the Wigner distribution, (2) the Choi-Williams distribution (ED), and (3) the authors' new kernel (named eight figure-kernel), that has high resolution. The results show that the demodulation accuracy with the authors' new kernel is higher and the negative components are smaller than the ED, which makes the cross-term small.

关键词： Time frequency analysis Kernel Signal analysis Speech analysis Ultrasonic imaging Signal resolution Steel Blood flow Ultrasonic variables measurement Petroleum

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A new role of graphical simulation: Software testing

A new role of graphical simulation: Software testing

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Annual Symposium on Simulation

作者： J.-Y. Jo Y.-W. Kim S.A. Ameduri A. Podgurski Computer Engineering & Science Department Case Western Reserve University Cleveland OH USA Electrical Engineering & Applied Physics Department Center for Automation and Intelligent Systems Research Case Western Reserve University Cleveland OH USA

Simulation is an effective technique to test software where testing in the real environment is not feasible. A 3D graphical simulator can make the software testing process much more effective and efficient. With graphical representation, the software's behavior can be observed in a virtual environment similar to the real environment. This kind of simulator can be best used in testing embedded system software, specifically in systems with many moving objects. Typically, however, the creation of a simulator is expensive in terms of time and cost. In addition, it is difficult to verify the accuracy of the system. We propose an inexpensive 3D graphical simulation method for software testing of embedded systems. This system eliminates the need for mathematical modeling by modeling the physical objects with simple rules. These objects self-coordinate their operation through the application of these rules. The 3D graphical simulator integrates the entire modeling process, eliminating the need for separate simulation and graphical display units. The simulator provides instant graphical feedback of system behavior to illustrate the feasibility and reliability of the system.

关键词： Software testing Embedded system Mathematical model Virtual environment System testing Embedded software Software systems Costs Application software Three dimensional displays

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Chemical-Mechanical Polishing of Polymer Films: Comparison of Benzocyclobutene(BCB) and Parylene-N Films by XPS and AFM

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MRS Online Proceedings Library 1997年第1期476卷 161-172页

作者： G.-R. Yang Y.-P. Zhao Jan M. Neirynck Shyam P. Murarka Ronald J. Gutmann Department of Physics Applied Physics and Astronomy Center for Integrated Electronics and Electronic Manufacturing Rensselaer Polytechnic Institute Troy USA Department of Electrical Computer and Systems Engineering Center for Integrated Electronics and Electronic Manufacturing Rensselaer Polytechnic Institute Troy USA Department of Materials Science and Engineering Center for Integrated Electronics and Electronic Manufacturing Rensselaer Polytechnic Institute Troy USA

The quality of benzocyclobutene (BCB) and Parylene-N (PA-N) films after chemical-mechanical polishing (CMP) is influenced by 3 factors: slurry composition, quality of the as-deposited film or post-deposition treated film, and polishing time. The quality of the films has been investigated by using X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). It is shown that the higher the quality of the as-deposited film (or post-deposition treated film), the higher the quality of the polished film. The polishing time has little effect on the surface characteristics of high quality PA-N films, however it has an effect on BCB film. This is attributed to the structure and thermal-stability and higher chemical resistance of PA-N. The RMS surface roughness measured by AFM, for as-deposited PA-N is 90Å. The roughness after CMP processes is greater than 200Å. The roughness for as-spin-coated and polished BCB film is 5Å, and 20Å, respectively. The morphology of the PA-N film, either as-deposited or polished, is not as good as the BCB film. A slurry which is good for BCB polishing is not good for PA-N polishing, and vice versa. These results indicate that the nature of the polymer film, including its chemical structure as well as the quality of the as-deposited/post-deposition treated film, plays an important role in polymer CMP.

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Higher-efficiency Si LED's with standard CMOS technology

Higher-efficiency Si LED's with standard CMOS technology

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IEEE Workshop on, High Performance Electron Devices for Microwave and Optoelectronic Applications

作者： L.W. Snyman A. Biber H. Aharoni M. du Plessis B.D. Patterson P. Seinz Department of Applied Solid State Physics Paul Scherrer Institut Switzerland Carl and Emily Fuchs Institute for Microelectronics Department of Electrical and Electronic Engineering University of Pretoria Pretoria South Africa Department .of Applied Solid State Physics Centre Suisse d''Electronique et de Microtechnique Zurich Switzerland University of Pretoria from the Department of Electrical and Computer Engineering Ben-Gurion University of the Negev Beersheba Israel Carl and Emily Fuchs Institute for Microelectronics Department of Electrical and Electronic Engineering University of Pretoria South Africa Department of Applied Solid State Physics Paul Scherrer Institute Villigen Switzerland

Multi-junction silicon light emitting devices (Si LED's) were designed and realised by using standard 1.2 micron and 2 micron CMOS processes with a bipolar capability and with no modifications to the processes. The designs were optimised to increase the power conversion efficiency, quantum conversion efficiency, intensity of emission and also the uniformity of emission. The devices emit light of several nW per 5 to 10 mA at 4-30 V in the 450 to 850 nm wavelength range. All the devices operated with at least one pn junction in the field emission or avalanche breakdown mode. Quantum conversion efficiencies of up to 1/spl times/10/sup -5/ have been measured which is two and a half orders to three orders of magnitude higher than previously published values for light emission from Si p-n avalanching junctions. Some directional light emission characteristics were also observed. The developed devices are viable for on-chip electro-optical applications and also for high speed chip-to-environment electro-optical applications.

关键词： CMOS technology Electrooptic devices Silicon CMOS process Process design Design optimization Power conversion Avalanche breakdown Semiconductor device measurement Wavelength measurement

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A flexible software architecture for agile manufacturing

A flexible software architecture for agile manufacturing

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IEEE International Conference on Robotics and Automation (ICRA)

作者： Yoohwan Kim Ju-Yeon Jo V.B. Velasco N.A. Barendt A. Podgurski G. Ozsoyoglu F.L. Merat Computer Engineering & Science Department Center for Automation and Intelligent Systems Research Case Western Reserve University Cleveland OH USA Electrical Engineering & Applied Physics Department Center for Automation and Intelligent Systems Research Case Western Reserve University Cleveland OH USA

The flexibility required of an agile manufacturing system must be achieved largely through computer software. The system's control software must be adaptable to new products and to new system components without becoming unreliable or difficult to maintain. This requires designing the software specifically to facilitate future changes. As part of the Agile Manufacturing Project at Case Western Reserve University, we have developed a software architecture for control of an agile manufacturing workcell, and we have demonstrated its flexibility with rapid changeover and introduction of new products. In this paper, we describe the requirements for agile manufacturing software and how our software architecture addresses them.

关键词： Software architecture Agile manufacturing Hardware Robotic assembly Control systems Motion control computer aided manufacturing computer architecture Machine vision physics computing

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Transient and Stationary Field Emission Currents from Semiconductors Computed by a Simple Semi-Classical Method

Transient and Stationary Field Emission Currents from Semico...

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IEEE International Conference on Vacuum Microelectronics (IVMC)

作者： V. Filip D. Nicolaescu C.N. Plavitu F. Okuyama Faculty of Physics University of Bucharest Romania New Jersey Institute of Technology Department of Electrical and Computer Engineering University Heights Newark NJ USA Hyperion University and Research Institute Bucharest Romania Applied Physics Laboratory Nagoya Institute of Technology Nagoya Japan

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Performance Evaluation of an On-Line Self-Learning Fuzzy Logic Controller applied to Non-Linear Processes

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IFAC Proceedings Volumes 1997年第9期30卷 245-250页

作者： S.H. Ghwanmeh K.O. Jones D. Williams Computer and Control Department Hijjawi Faculty for Applied Engineering Yarmouk University 211-63 Jrbid Jordan Control Systems Research Group School of Electrical Engineering Electronics and Physics Liverpool John Moores University Byrom Street Liverpool L3 3AF United Kingdom E-mail:

The generation of rule-bases in conventional fuzzy logic controllers can be a difficult and time consuming problem for implementation by process operators thus affecting their wider applicability. A Self-Learning Fuzzy Logic Control (SLFLC) offers a possible solution. A performance study is therefore presented to evaluate the performance of a proposed SLFLC by analysing its transient performance for a variety of on-line tests and examining its ability to generate a consistent set of rules, based on a predetermined criteria. The results presented show that even with a limited knowledge of the process, the self-learning procedure is able to develop a suitable set of rules and produce a satisfactory process performance with some degree of robustness and repeatability when applied to a non-linear single-input single-output (SISO) or multi-input multi-output (MIMO) laboratory liquid-level processes.

关键词： Fuzzy logic self-adaptive control on-line control non-linear control

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