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IEEE International Conference on systems, Man and Cybernetics

作者： T. Oki T. Yamamoto N. Kaneda S. Omatsu Department of Communication Engineering Faculty of Computer Science and Systems Engineering Okayama Prefectural University Soja Okayama Japan Department of Computer and Systems Sciences College of Engineering Osaka Prefecture University Sakai Osaka Japan

It is difficult to control nonlinear systems using a PID controller with fixed gains. Many types of PID controllers with variable gains have been proposed based on advanced control techniques. In this paper, an advanced PID controller for nonlinear systems is proposed. Since the nonlinear input/output characteristics can be explained using a set of linear input/output characteristics, we consider that a set of linear system self-tuning PID controllers are used through switching based on signals from the control system. The switching is carried by a neural network based supervisor. This supervisor selects the linearized model which is most accurate for the next step. The effectiveness of this method is investigated through two numerical simulations.

关键词： Three-term control Control systems Nonlinear control systems Nonlinear systems Neural networks Linear systems Intelligent control Control system synthesis Pi control Proportional control

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Reduction Of Iron Loss In Thin Grain-oriented Stltcon Steel Sheets

Reduction Of Iron Loss In Thin Grain-oriented Stltcon Steel ...

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International Conference on Magnetics (INTERMAG)

作者： M. Nakano K. Ishiyama K.I. Arai H. Fukunaga Department of Electrical Engineering and Computer Science Faculty of Engineering Nagasaki University Nagasaki Japan Research Institute of Electrical Communication University of Tohoku Sendai Japan

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Digital Adaptive Motion Control for a Servo Mechanism

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IFAC Proceedings Volumes 1997年第11期30卷 323-328页

作者： T. Suehiro F. Ohkawa T. Hokamura S. Sagara Electronics Division Mechanics & Electronics Research Institute Fukuoka Industrial Technology Center 3-6-1 Norimatsu. Yahatanishi-ku Kitakyushu-shi 807 Japan Department of Control Engineering and Science Faculty of Computer & System Engineering Kyushu Institute of Technology lizuka 820 Japan Department of Control Engineering Faculty of Engineering Kyushu Institute of Technology Tobata Kitakyushu 804 Japan

This paper is concerned with an application of a digital adaptive control system to a servo mechanism. Mechanical systems in general include nonlinearities and additional uncertainties and which result from inertia and friction. So it is difficult to ensure robust performance and high accuracy for motion control. The digital adaptive control system presented here is considered to overcome the above stated problem. Experimental results from a feed drive system demonstrate the effectiveness of the proposed control scheme.

关键词： Adaptive Control Servomechanism Nonlinearity Uncertainty Friction

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Adaptive Speed Control Using an RBF Network for a Servo Motor in the Presence of Angle Dependent Disturbances

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IFAC Proceedings Volumes 1997年第11期30卷 59-64页

作者： Zi-jiang Yang Koichi Hirata Teruo Tsuji Faculty of Computer Engineering and System Science Kyushu Institute of Technology Iizuka Fukuoka 820 Japan TEL: +81-948-29-7672 FAX: +81-948-29-7651 Department of Electrical Engineering Kyushu Institute of Technology 1-1 Sensui-cho Tobataku Kitakyushu 804 Japan

It is well-known that the angle dependent disturbances in a servo motor caused by nonuniformity of field windings, armature cogging, rotor imbalance, nonuniform load etc., may influence the speed control performance greatly. This often leads to large speed fluctuations which are undesired in practical situations. Therefore speed fluctuation reduction techniques in the presence of angle dependent disturbances are strongly required and have been being challenged by a lot of researchers. In this paper, the authors propose a new approach to this problem via adaptive control with the aid of a radial basis function (RBF) network composed of gaussian basis functions. The angle dependent disturbances which are viewed as a periodic nonlinear function with a period of 2π[rad] in the angle-domain, is approximated by a RBF network in the domain of [0, 2π)[rad]. Then an adaptive linearization control system employing the RBF network which compensates the disturbances is proposed. The RBF network has the advantage that it is linear-in-parameter and hence the parameter adaption is very fast and easy to implement. It is proved through theoretical analysis that the stability of the adaptive control is guaranteed by the Lyapunov stability theory. Finally, simulational and experimental results are included in the paper to show the excellent performance of the proposed method.

关键词： Servo motor speed control angle dependent disturbance RBF network adaptive control stability

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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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An importance sampling for the coded satellite systems with memory

An importance sampling for the coded satellite systems with ...

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IEEE International Conference on communications (ICC)

作者： Sung-Chan Ko Junghwan Kim Jae-Moung Kim Ji Won Jung Department of Information and Communication National An Dong University Gyeongsangbuk South Korea Department of Electrical Engineering and Computer Sciense University of Tolctlo and Eötvös Lárand University Toledo OH USA Satellite Communications System Division Electronics and Telecommunications Research Institute Taejon South Korea Department of Radio Science and Engineering Korea Maritime University busan South Korea

ISBN: (纸本)0780339258

For the estimation of average bit error rate (BER) of complex digital communication systems, Monte-Carlo (MC) simulation technique has been widely used because of its simplicity. However, it requires excessively long execution time to estimate lower BER. Although this time can substantially be reduced by using importance sampling (IS), IS has not been quite successful in the simulation of practical nonlinear satellite communication systems that typically consist of memory components and forward error correction (FEC) scheme. In this paper, we propose a new algorithm for the simulation of Viterbi decoder using sequentially implemented IS. We then combine it with the efficient importance sampling (EIS) technique to resolve the problems associated with memory. Results from this integration exhibit dramatic reduction of simulation time. Principles of the new simulation method of Viterbi decoding are presented. Details on the integration with EIS are followed with some numerical examples.

关键词： Monte Carlo methods Decoding Bit error rate Viterbi algorithm Computational modeling Satellite communication Forward error correction Discrete event simulation Convolutional codes Digital communication

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Robust adaptive sliding mode control with modified regressor matrix and composite adaptation for robotic manipulators

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Advanced Robotics 1997年第1期12卷 53-66页

作者： Chong, Sze San Yu, Xinghuo Zhihong, Man KDU Penang Penang 10400 32 Jalan Anson Malaysia Faculty of Informatics and Communication Central Queensland University Rockhampton Queensland 4702 Australia Department of Electrical Engineering and Computer Science University of Tasmania Tasmania 7001 Australia

A robust adaptive sliding mode controller is proposed in this paper for trajectory tracking in rigid robotic manipulators. This controller contains two components: one is for estimation of the constant part of system parameters and the other for suppression of the uncertainty part ofsystem parameters. With a mild assumption, the proposed controller enables the desired trajectory to be tracked. In order to further enhance the performance of the controller, the regressor matrix is modified and composite adaptation is incorporated so that the acceleration signals are notrequired for control. Simulations are presented to show the effectiveness of the approach. © VSP and Robotics Society of Japan 1998.

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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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A comparative study of the effective dielectric constant of a medium containing randomly distributed dielectric spheres embedded in a homogeneous background medium

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WAVES IN RANDOM MEDIA 1996年第4期6卷 347-360页

作者： Nanbu, Y Tateiba, M [a] Department of Electrical Engineering Sasebo National College of Technology Sasebo Japan [b] Department of Computer Science and Communication Engineering Faculty of Engineering Kyushu University Fukuoka Japan

The effective dielectric constant epsilon(eff) of a medium containing randomly distributed dielectric particles has been analysed by conventional methods: Foldy's approximation, the quasi-crystalline approximation (QCA) and the QCA with coherent potential. These conventional methods, however, have been indicated to become invalid for particles with a high dielectric constant;we have thus presented a new method that is valid for them. This paper compares epsilon(eff) of our method with those of the conventional methods by changing the volume fraction and the dielectric constant of spheres. As a result, our method is shown to be more powerful for the analysis of epsilon(eff) than the conventional methods.

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