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CONCURRENT LARGE-SIGNAL SIMULATION OF AN ACTIVE MICROSTRIP ANTENNA

INTERNATIONAL JOURNAL OF NUMERICAL MODELLING-ELECTRONIC NETWORKS DEVICES AND FIELDS 1995年第1期8卷 3-12页

作者： MCDOWALL, DS FUSCO, VF High Frequency Electronics Laboratory. Department of Electrical and Electronic Engineering The Queen's University of Belfast Ashby Building Stranmillis Road Belfast BT9 5AH U.K. D. Stewart McDowall was born in Dublin Republic of Ireland in 1967. He received the M. Eng. degree in Electrical and Electronic Engineering from the Queen's University of Belfast in 1990. In the same year he was presented with a Distinction Award from the Departmnet of Education of Northern Ireland and he is currently pursuing his Ph.D. in the Microwave Research Group at Q.U.B. His principal research area is the electromagnetic field mapping of microwave systems using concurrent programming. He is an Associate Member of the Institute of Electrical Engineers. Vincent F. Fusco was educated at the Queens's University of Belfast where he obtained the degree of Ph.D. in 1982. He has worked as a research engineer on short-range radar and radio telemetry systems. Currently he is a reader in Microwave Communications in the School of Electrical engineering and Computer Science the Queen's University of Belfast. His current research interests include non-linear microwave circuit simulatino and concurrent programming techniques for electromagnetic field problems with particular emphasis on EMC applications. He has published numerous research papers in these areas. He is the author of the bookMicrowave Circuits Analysis and Computer Aided Design Prentice-Hall 1987. Dr Fusco is a Chartered Electrical Engineer and a Member of the Institute of Electrical Engineers.

This paper details the use of a circuit-based EM modelling technique combined with a harmonic balance simulator used to model the radiation from the microstrip bodies comprising an active antenna circuit. The modelling approach adopted for the planar bodies in the circuit will be shown to allow the use of concurrent algorithms in order to reduce overall computational time.

关键词： Microstrip antennas

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INGAAS ALAS INGAASP RESONANT-TUNNELING HOT-ELECTRON TRANSISTORS GROWN BY CHEMICAL BEAM EPITAXY

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IEEE TRANSACTIONS ON ELECTRON DEVICES 1994年第2期41卷 155-161页

作者： CHEN, WL MUNNS, GO EAST, JR HADDAD, GI Center of High Frequency Microelectronics Solid State Electronics Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI USA

InP-based resonant tunneling hot electron transistors (RHET's) were studied systematically using chemical beam epitaxy (CBE) for the first time. All the RHET's studied have a highly strained AlAs/In0.75Ga0.25As/AlAs resonant tunneling double barrier as a hot electron injector, and an InP collector barrier with or without InGaAsP graded layers. The highest transport ratio (alpha) observed is 0.98, and the highest peak-to-valley current ratios (PVR's) measured are 20 and 200 in the collector current and base current, respectively, at 80 K. A self-consistent simulation is used as a reference to optimize the hot electron injector and to explain the ballistic transport. An energy spectrometer technique was applied to the RHET's for resolving the hot electron energy distribution which showed a full width at half maximum (FWHM) of around 58 meV, indicating ballistic transport of electrons. Finally, room temperature transistor action was also observed with a beta of 4 and a cutoff frequency of 31 GHz.

关键词： Indium gallium arsenide Resonant tunneling devices Ballistic transport Electron beams Chemicals Molecular beam epitaxial growth Epitaxial growth Indium phosphide Current measurement Pareto optimization

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THE GROWTH OF RESONANT-TUNNELING HOT-ELECTRON TRANSISTORS USING CHEMICAL BEAM EPITAXY

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JOURNAL OF CRYSTAL GROWTH 1994年第1-4期136卷 50-55页

作者： CHEN, WL MUNNS, GO DAVIS, L BHATTACHARYA, PK HADDAD, GI Center for High Frequency Microelectronics Solid-State Electronics Laboratory Department of Electrical Engineering Computer Science The University of Michigan Ann Arbor Michigan 48109-2122 USA

A systematic growth study of InGaAs/AlAs/InGaAsP resonant tunneling hot electron transistors (RHETs) was performed using chemical beam epitaxy (CBE). The resonant tunneling hot electron transistors studied consist of a highly strained AlAs/In0.75Ga0.25As/AlAs double barrier structure and an undoped InP collector barrier with 1.1 and 1.2 mum InGaAsP graded layers. These quaternaries were lattice matched to InP within 2.6 X 10(-4) and showed an averaged full width at half-maximum (FWHM) of 6 meV from low temperature photoluminescence (PL) measurement. The effects of growth interrupt were studied using PL, X-ray diffraction and secondary ion mass spectrometry (SIMS) measurements. It was found that excessive growth interrupt induced high oxygen accumulation (8 X 10(18) cm-3) at the heterojunction and reduced the intensity of PL spectra. Moreover, for the growth of tunneling heterostructures, low substrate temperature, appropriate growth interrupts and use of hydride drying filters and high purity hydrides were helpful to improve device performance. The highest peak-to-valley current ratio (PVR) observed was 12.7, and maximum base transport ratio was 0.98 at 80 K. Furthermore, some digital functions such as flip-flop gate and exclusive NOR were demonstrated using a single RHET.

关键词： Transistors

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Parallelization of a 3D multi-block Navier-Stokes flow solver on a distributed memory MIMD machine

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International Conference and Exhibition on high-performance Computing and Networking, HPCN 1994

作者： van Beek, G. Geschiere, J.P. Sukul, A.R. National Aerospace Laboratory NLR Informatics Division P.O. Box 90502 AmsterdamBM1006 Netherlands Leiden University Department of Computer Science High Performance Computing Division P.O. Box 9512 Leiden2300 RA Netherlands Vrije Universiteit Amsterdam Department of Computer Science and Mathematics De Boelelaan 1081a Amsterdam1081 HV Netherlands

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Simplified nonlinear model for the intermodulation analysis of MESFET mixers

Simplified nonlinear model for the intermodulation analysis ...

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Microwave, MTT-S International Symposium

作者： Sotli Peng P.J. McCleer G.I. Haddad Center for High Frequency Microelectronics Solid State Electronics Laboratory Department of Electrical Engineering and Computer Science University of Michigan USA

A simplified nonlinear model is proposed for intermodulation (IM) analysis of MESFET gate mixers. The accuracy of the model has been verified experimentally using two different MESFET mixers at X-band. Both tests show excellent agreement between measurement and simulated data for second- and third-order IM performance. The simplified model is based on modeling the derivative of the device transconductance by the sum of a Gaussian function and a linear function of the gate voltage. Drain bias dependence is ignored. The advantage of this model is that the fitting parameters can be easily determined from a nonlinear characterization of the device at low frequencies.< >

关键词： MESFETs Testing Transconductance Voltage Frequency

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An environment for importance sampling based on stochastic activity networks

An environment for importance sampling based on stochastic a...

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Reliable Distributed Systems

作者： W.D. Obal W.H. Sanders Department of Electrical and Computer Engineering University of Arizona Tucson Tucson AZ USA Center for Reliable and High-Performance Computing Coordinated Science Laboratory University of Illinois Urbana-Champaign Urbana IL USA

Model-based evaluation of reliable distributed and parallel systems is difficult due to the complexity of these systems and the nature of the dependability measures of interest. The complexity creates problems for analytical model solution techniques, and the fact that reliability and availability measures are based on rare events makes traditional simulation methods inefficient. Importance sampling is a well-known technique for improving the efficiency of rare event simulations. However, finding an importance sampling strategy that works well in general is a difficult problem. The best strategy for importance sampling depends on the characteristics of the system and the dependability measure of interest. This fact motivated the development of an environment for importance sampling that would support the wide variety of model characteristics and interesting measures. The environment is based on stochastic activity networks, and importance sampling strategies are specified using the new concept of the importance sampling governor. The governor supports dynamic importance sampling strategies by allowing the stochastic elements of the model to be redefined based on the evolution of the simulation. The utility of the new environment is demonstrated by evaluating the unreliability of a highly dependable fault-tolerant unit used in the well-known MARS architecture. The model is non-Markovian, with Weibull distributed failure times and uniformly distributed repair times.< >

关键词： Monte Carlo methods Stochastic processes Analytical models Discrete event simulation Availability Sampling methods Stochastic systems computer network reliability computer networks Concurrent computing

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A standard simulation environment: a review of preliminary requirements 94

A standard simulation environment: a review of preliminary r...

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Simulation Winter Conference

作者： M.A.F. Wagner S. Sevinc O. Tanir P.L. Haigh J.D. Arthur R.E. Nance H.D. Schwetman SysTech Software Solutions Annandale VA USA Knowledge Systems Group Basser University of Sydney Australia Quality Engineering and Research (QER) Group Longueuil QUE Canada High Performance Software Inc. Dayton OH USA Systems Research Center Department of Computer Science Virginia Polytechnic Institute and State University Blacksburg VA USA Mesquite Software Inc. Austin TX USA

ISBN: (纸本)9780780321090

The concept of a simulation environment combines different aspects of the simulation process into one complete powerful tool. The environment should provide the necessary state-of-the-art advances and concepts that a modeler may require during the simulation development and execution process. The "environment" requirements must address the end user needs while minimizing the necessity of learning a new language. The requirements must specify the useful features, independent of different platforms and implementation languages. Hence the opportunity exists for standardization of environments. The paper opens a discussion on challenges and rewards awaiting the simulation community with the advent of a standard environment.

关键词： Power system modeling Computational modeling computer simulation Standardization Knowledge based systems Australia Knowledge engineering Software performance Drives computer science

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A SELF-CONSISTENT MODEL OF GAMMA-X MIXING IN GAAS/ALAS/GAAS QUANTUM-WELL STRUCTURES USING THE QUANTUM TRANSMITTING BOUNDARY METHOD

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JOURNAL OF APPLIED PHYSICS 1993年第8期74卷 5053-5060页

作者： SUN, JP MAINS, RK YANG, K HADDAD, GI Center for High‐Frequency Microelectronics Solid State Electronics Laboratory Department of Electrical Engineering and Computer Science The University of Michigan Ann Arbor Michigan 48109

We present a numerical study of the GAMMA-X mixing in GaAs/AlAs/GaAs quantum well structures. A GAMMA-X mixing model proposed by Liu [Appl. Phys. Lett. 51, 1019 (1987)] is extended to include the effects of self-consistency and nonzero transverse momentum. In the present model, the coupled Schrodinger equations for GAMMA and X electron envelope wave functions are solved self-consistently with Poisson's equation to calculate the electron transmission probability and wave functions, which lead to the current-voltage (I-V) characteristics of single barrier and double barrier resonant tunneling diode structures. The quantum transmitting boundary method is employed in the model for numerical solution of the coupled Schrodinger equations, which proves to be very stable and efficient, even for large (> 2000 angstrom) structures. The features of GAMMA-X mixing, such as the resonance/antiresonance in the transmission probability and the virtual bound states, are clearly demonstrated. Additional physical features are observed in the transmission probability and the wave functions under applied bias conditions. Our work shows that inclusion of transverse momentum, variable effective mass, and the self-consistent potential is important in the realistic modeling of I-V characteristics for structures exhibiting GAMMA-X coupling.

关键词： QUANTUM WELLS GALLIUM ARSENIDES ALUMINIUM ARSENIDES IV CHARACTERISTIC BAND STRUCTURE SCHROEDINGER EQUATION WAVE FUNCTIONS POISSON EQUATION TRANSMISSION SELF?CONSISTENT FIELD NUMERICAL SOLUTION

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Shepard’s interpolation for solution-adaptive methods

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Journal of Computational Physics 1993年第1期106卷 52-61页

作者： Shen, Cherng-Yeu Reed, Helen L. Foley, Thomas A. Mechanical and Aerospace Engineering Department Arizona State University Tempe AZ United States Computer Science and Engineering Department Arizona State University Tempe AZ United States National Cemter for High-Performance Computing Taiwan

In numerical simulations of fluid-dynamics problems, solution-adaptive methods have proven to be very powerful. The implementation of the modified Shepard’s interpolation to the structured grids used in CFD is suggested and described in this paper, which takes advantage of the logical grid structure. This technique, which is demonstrated to be robust, efficient, smoother, and a more accurate alternative to linear interpolation, is used in the remapping step during the solution-adaption procedure. Applications to the solutions of the incompressible Navier Stokes equations (both 2D and 3D) are included. © 1993 by Academic Press, Inc.

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Chapter 6 DX and Related Defects in Semiconductors

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Semiconductors and Semimetals 1993年第C期38卷 235-291页

作者： Malloy, Kevin J. Khachaturyan, Ken Center for High Technology Materials Department of Electrical Computer Engineering University of New Mexico Albuquerque NM United States Center for Materials Science Los Alamos National Laboratory Los Alamos NM United States

This chapter discusses DX and related defects in semiconductors. Often, the most difficult aspect of research into semiconductor defects is arriving at an accurate description of the properties of the defect enabling the study of the defect by any laboratory. While observations of the optical, electrical, and environmental behavior of a defect form a useful starting point, uncertainty over the necessary and sufficient properties for observation and investigation of the defect can linger for a surprisingly long time. Research on the DX center fully reflects these difficulties. Only when the atomic nature and workings of the defect are understood do the interpretations of the defect begin to converge. Such explicit atomic-level understanding has been the goal of recent DX studies, along with attempts at first-principle theories of DX centers. The chapter also discusses the Hall measurements of the electrical properties of semiconductors. A typical Hall measurement consists of a plot of the logarithm of the Hall electron concentration as a function of the inverse temperature 1/ T in kelvins. The slope of such an Arrhenius plot is the standard free enthalpy change of an electron transition from a bound state to the conduction band minimum.

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