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Overview, current trends and latest results in estimating the effects of load modelling on power-system damping and stability

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EUROPEAN TRANSACTIONS ON ELECTRICAL POWER 1997年第2期7卷 107-113页

作者： Milanovic, JV [?]Jovica V. Milanovic (1967) received the Dipl.-Ing. (Elec.) and M.Sc. (Elec. Eng.) degrees from the University of Belgrade. Yugoslavia. in 1987 and I99 I respectively. One year he worked with “Energoproject-MDD”- Engineering and Contracting Co. in Belgrade as an engineer in designing power plants and substations. In late 1988 hejoined the Faculty of Electrical Engineering of the University of Belgrade first as an associate teaching assistant and then (since late 199 I) as teaching assistant at the Dept. of Power Converters and Drives. Between March 1993 and January 1996 he completed his Ph.D. at the University of Newcastle. Australia. at the Dept. of Electrical and Computer Engineering. Since February 1996 he is lecturer at the Department of Electrical Engineering and Computer Science at the University of Tasmania Austnlia. His major interests include synchronous machines and power system transients control and stability. (The University of Tasmania. Dept. of Electrical Engineering and Computer Science GPO Box 252-65 Hobart Tas 7001 Australia.Te1+61 362/262-753 Fax+61 369/262 136. e-mail: Jovica.Milanovic@eecs.utas.edu.au)

The paper presents the overview of load modelling for power-system damping and stability studies with main conclusions summarized from previous research. The attempt has been made to present a cross-section of the most exploited existing load models together with the most important conclusions drawn from their implementation in power-system stability programs. The current trends and latest results in the domain of damping of electromechanical oscillations in power systems are also presented. The effects of load dynamics on damping of electromechanical oscillations were analyzed on the basis of one of generic load models proposed in the past. The recent results further encourage investigation in this area and highlights the importance of proper load modelling.

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Localized Excitons in InGaN

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MRS Online Proceedings Library 1997年第1期482卷 648-659页

作者： S. Cmchibu T. Deguchi T. Sota K. Wada S. Nakamura Materials Department University of California Santa Barbara USA Faculty of Science and Technology Science University of Tokyo Chiba 278 Japan Department of Electrical Electronics and Computer Engineering Waseda University Tokyo 169 Japan Compound Semiconductor Materials Research NTT System Electronics Laboratories Kanagawa Japan Department of Research and Development Nichia Chemical Industries Ltd. Tokushima 774 Japan

Emission mechanisms of the device-quality quantum well (QW) structure and bulk three dimensional (3D) InGaN materials grown on sapphire substrates without any epitaxial lateral overgrown GaN (ELOG) base layers were investigated. The InxGx1−xN layers showed various degree of spatial potential (bandgap) fluctuation, which is probably due to a compositional inhomogeneity or monolayer thickness fluctuation produced by some kinetic driving forces initiated by the threading dislocations (TDs) or growth steps during the growth. The degree of fluctuation changed remarkably around nominal InN molar fraction x=0.2, which changes to nearly 8–10 % for the strained InxGa1−xN. This potential fluctuation induces energy tail states both in QW and 3D InGaN, showing a large Stokes-like shift combined with the red shift due to quantum confined Stark effect (QCSE) induced by the piezoelectric field. The spontaneous emission from undoped InGaN single quantum well (SQW) light-emitting diodes (LED’s), undoped 3D double heterostructure (DH) LED’s, and multiple quantum well (MQW) laser diode (LD) wafers was assigned as being due to the recombination of excitons localized at the potential minima, whose area was determined by cathodoluminescence (CL) mapping to vary from less than 60 nm to 300 nm in lateral size in the case of QW’s. The lasing mechanisms of the cw In0.15Gao.85N MQW LD’s having small potential fluctuation, whose bandgap broadenings are less than about 50 meV, can be described by the well-known electron-hole-plasma (EIHP) picture with Coulomb enhancement. The inhomogenous MQW LD’s are considered to lase by EHP in segmented QW’s or Q-disks. It is desirable to use entire QW planes with small potential inhomogeneity as gain media for higher performance LD operation.

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Developing a prototype concurrent design tool for composite topside structures

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NAVAL ENGINEERS JOURNAL 1997年第3期109卷 279-290页

作者： Dirlik, S Hambric, S Azarm, S Marquardt, M Hellman, A Bartlett, S Castelli, V Steve Dirlik:began his career at the Naval Surface Warfare Center Carderock Division in 1981 as an aerospace engineer co-op student. He completed his bachelor of science degree in aeropace and ocean engineering from Virginia Polytechnic Institute and State University in 1985 and his master of science degree in aerospace engineering from the University of Maryland in 1990. Mr. Dirlik recently completed a master of science program in applied physics at The Johns Hopins University and currently works in the Radar Cross Section and Target Physics Branch of the Signatures Directorate at the Naval Surface Warfare Center Corderoke Division. He has worked on Navy low observable programs since 1990. Stephen Hambric:is a research associate at the Applied Research Laboratory at The Pennsylvania State University. He received his B. S. and M.S. degree in mechanical engineering from Virginia Polytechnic Institute and State University and his D. Sc. in mechnical engineering from the George Washington University. He has worked on several computer aided multidiscikplinary design and optimization projects over the years including an automated propeller design system and a structural acoustic optimization capability. Dr. Shpour Azarm:is currently working as an associate professor with the Design and Manufacturing Group of the Department of Mechanical Engineering at the University of maryland at College Park. Dr Azarm's expertise is in the areas of optimization-based designed and concurrent design and optimization of multidisciplinary systems. He was a consultant at Black & Decker Corporation (summer 1996) and worked as a Navy senior summer faculty fellow (summer 1995) and a NASA summer faculty fellow (summer 1994). He was a visiting scientist at NASA Langley Research Center for Multidisciplinary Analysis and Applied Structural Optimzatiom at the University of Siegen in Germany (spring 1992) and the Design Institute of the Technical University of Denmark (summer 1990). Dr Azarm was an associate technical editor of the ASME Jour

A prototype concurrent engineering tool has been developed for the preliminary design of composite topside structures for modern navy warships. This tool, named GELS for the Concurrent engineering of Layered Structures, provides designers with an immediate assessment of the impacts of their decisions on several disciplines which are important to the performance of a modern naval topside structure, including electromagnetic interference effects (EMI), radar cross section (RCS), structural integrity, cost, and weight. Preliminary analysis modules in each of these disciplines are integrated to operate from a common set of design variables and a common materials database. Performance in each discipline and an overall fitness function for the concept are then evaluated. A graphical user interface (GUI) is used to define requirements and to display the results from the technical analysis modules. Optimization techniques, including feasible sequential quadratic programming (FSQP) and exhaustive search are used to modify the design variables to satisfy all requirements simultaneously. The development of this tool, the technical modules, and their integration are discussed noting the decisions and compromises required to develop and integrate the modules into a prototype conceptual design tool.

关键词： Warships

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Cellular neural networks with multiple-valued output and its application

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IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND computer scienceS 1996年第10期E79A卷 1658-1663页

作者： Kanagawa, A Kawabata, H Takahashi, H Faculty of Computer Science and System Engineering Okayama Prefectural University Soja-shi 719-11 Japan

Various applications of cellular neural network (CNN) are reported such as a feature extraction of the patterns, an extraction of the edges or corners of a figure, noise exclusion, searching in maze and so forth. In this paper, we propose a cellular neural network whose each cell has more than two output levels. By using the output function which has several saturated levels, each cell turns to have several output states. The multiple-valued CNN enhances its associative memory function so as to express various kinds of aspects. We report an application of the enhanced associative memory function to a diagnosis of the liver troubles.

关键词： cellular neural network associative memory classification problem

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Implicit representation and manipulation of binary decision diagrams

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IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND computer scienceS 1996年第3期E79A卷 354-362页

作者： Yamauchi, H Ishiura, N Takahashi, H Faculty of Computer Science and System Engineering Okayama Prefectural University Soja-shi 719-11 Japan Faculty of Information System Engineering Osaka University Suita-shi 565 Japan

This paper presents implicit representation of binary decision diagrams (implicit BDDs) as a new efficient data structure for Boolean functions. A well-known method of representing graphs by binary decision diagrams (BDDs) is applied to BDDs themselves. Namely, it is a BDD representation of BDDs. Regularity in the structure of BDDs representing certain Boolean functions contributes to significant reduction in size of the resulting implicit BDD representation. Since the implicit BDDs also provide canonical forms for Boolean functions, the equivalence of the two implicit BDD forms is decided in time proportional to the representation size. We also show an algorithm to manipulate Boolean functions on this implicit data structure.

关键词： binary decision diagram (BDD) representation of Boolean functions logic design verification logic synthesis implicit representation of graphs

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On the unequal error protection capability of a q-ary image of a low-rate q(m)-ary cyclic code

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IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND computer scienceS 1996年第9期E79A卷 1305-1312页

作者： Sakakibara, K Kasahara, M Yuba, Y Faculty of Computer Science and System Engineering Okayama Prefectural University Soja-shi 719-11 Japan Faculty of Engineering and Design Kyoto Institute of Technology Kyoto-shi 606 Japan

An algorithm for finding the unequal error protection (UEP) capability of a q-ary image of a low-rate q(m)-ary cyclic code is presented by combining its concatenated structure with the UEP capability of concatenated codes. The results are independent of a choice of a basis to be used for expanding an element over GF (q(m)) into GF (q). A table of the UEP capability of binary images of low-rate Reed-Solomon codes over GF(2(6)) is given. It is shown that the encoding and decoding algorithms for superimposed concatenated codes can be applied to a q-ary image as a linear UEP code.

关键词： unequal error protection q-ary image of q(m)-ary cyclic code concatenated structure

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Some optical and quasi-optimal binary codes from cyclic codes over GF (2(m))

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IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND computer scienceS 1996年第10期E79A卷 1737-1738页

It is shown that five optimal and one quasi-optimal binary codes with respect to the Griesmer bound can be obtained from cyclic codes over GF(2(m)). An [m(2(em)-1), em, 2(em-1)m] code, a [3(2(2e)-1), 2e, 3 . 2(2e-1)] code, a [2(2(2e)-1), 2, (2(2e+2)-4)/3] code, a [3(2(2e)-1), 2, 2(2e+1)-2] code, and a [3(2(2e)-1), 2(e+1), 3 . 2(2e-1)-2] code are optimal and a [2(2(2e)-1)2(e+1), 2(2e)-2] code is quasi-optimal.

关键词： optimal binary codes binary image of cyclic codes Griesmer bound concatenated structure

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Matched design method for concatenated trellis-coded modulation

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IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND computer scienceS 1996年第11期E79A卷 1911-1917页

作者： Wadayama, T Wakasugi, K Kasahara, M Faculty of Computer Science and System Engineering Okayama Prefectural University Soja-shi 719-11 Japan Department of Electronics and Information Science Kyoto Institute of Technology Kyotoshi 606 Japan

A new design method, which is referred to as the matched design method, for concatenated trellis-coded modulation (TCM) is presented. Most of the conventional concatenated TCM employs TCM designed to maximize the minimum squared Euclidean free distance, d(free)(2). With the matched design method, we maximize d(1)(2)(t) instead of d(free)(2), where d(1)(2)(t) is the effective minimum squared Euclidean distance (MSED) when the outer code has a t-error correcting capability. The effective MSED is derived from the Euclidean/Hamming (E/H) joint weight distribution of terminated TCM. We here assume the concatenated TCM whose transmitted symbol corresponds to a symbol of outer code. The new classes of 2-dimensional(2D) and 4-dimensional(4D) codes are found by a computer search. Under the performance measures of the effective MSED or the effective multiplicity, these codes are superior to the conventional codes such as the Ungerboeck's 2D-codes when those are used as an inner code. We disclose an interesting fact that the new class of codes using rate-1/2 encoder is superior to the class of codes using rate-2/3 encoder. This fact implies that the codes using rate-1/2 encoder have two advantages: 1) better overall decoding performance and 2) less decoding complexity.

关键词： trellis-coded modulation concatenated code weight distribution

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Optical Fiber Demultiplexer-Star Coupler Using a Single GRIN-Rod Lens and a Multi-Facet Grating 11

Optical Fiber Demultiplexer-Star Coupler Using a Single GRIN...

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11th Optical Fiber Sensors Conference, OFS 1996

作者： Fukushima, Takehiro Sakamoto, Toyokazu Department of System Engineering Faculty of Computer Science and System Engineering Okayama Prefectural University 111 Kuboki Soja Okayama719-11 Japan

An optical fiber multi-function device using a single GRIN-rod lens and a multi-facet blazed reflection grating is proposed for realizing the functions of both demultiplexing and optical signal distribution. © 19... 详细信息

ISBN: (纸本)0819430447

关键词： Optical fibers

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A 7/spl times/6 optical fiber grating demultiplexer-multiposition switch for 0.64-0.88 /spl mu/m band

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Journal of Lightwave Technology 1996年第5期14卷 867-872页

作者： T. Fukushima T. Sakamoto Department of system Engineering Faculty of Computer Science and System Engineering Okayama Prefectural University Okayama Japan

An optical fiber grating demultiplexer-multiposition switch having seven demultiplexing channels and six position-switching channels is demonstrated. This device consists of a unique fiber array in which 42 output fibers are aligned radially around an input fiber, a single gradient-index (GRIN)-rod lens and a rotatable blazed reflection grating. In this device, seven demultiplexing channels can be switched to six different directions by rotating blazed reflection grating. Therefore, this device can realize total transmission channels of 42. The device had a working band of 0.64-0.88 /spl mu/m, a channel separation of 35-42 nm and a 3 dB band width of 18-22 nm. The deviations of center wavelengths among the switching channels were suppressed less than 3 nm.

关键词： Optical fibers Fiber gratings Optical switches Optical fiber devices Optical filters Demultiplexing Optical films Optical devices Lenses Optical reflection

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