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IEEE Conference on control Technology and Applications (CCTA)

作者： D. Hughes J.T. Wen Control Laboratory for Mechanical Structures (CLaMS) Center for Advanced Technology in Automation Robotics & Manufacturing Department of Electrical Computer and Systems Engineering Rensselaer Polytechnic Institute Troy NY USA

Smart materials such as piezoceramics and shape memory alloys (SMAs) exhibit significant hysteresis and in order to estimate the effect on open and closed loop control a suitable model is needed. One promising candidate is the Preisach independent domain hysteresis model that is characterized by the congruent minor loop and wiping out properties. Comparable minor loop and decaying oscillation test data for a multi-sheet piezoceramic actuator (made of lead zirconate titanate) attached to a flexible beam are presented and are seen to be very consistent with the two Preisach model properties. The commanded parameter is the sheet transverse electric field while the measured parameter is an approximately colocated strain induced in the beam. Equivalent data for a Nitinol SMA wire muscle, attached to the same beam, are also presented. The input and output parameters are the SMA current and a beam strain respectfully. The minor loop and wiping out evidence is less strong than that of the piezoceramic case, but encouraging. In all experiments the quasi-steady state responses were generated in order to avoid exciting beam flexible modes which would complicate the analysis.

关键词： Piezoelectric materials Shape memory alloys Hysteresis Strain measurement Shape control Open loop systems Testing Actuators Titanium compounds Electric variables measurement

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Synthesized passive feedback control of sensor-rich smart structures-experimental results

Synthesized passive feedback control of sensor-rich smart st...

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IEEE Conference on control Technology and Applications (CCTA)

作者： P. Akella J.T. Wen Control Laboratory for Mechanical Structures Department of Electrical Computer and Systems EngineeringCenter for Advanced Technology in Automation Robotics & Manufacturing Rensselaer Polytechnic Institute RPI Troy NY USA

Passivity based controllers are used in structural control due to their inherent robustness properties. These controllers require sensor/actuator collocation. In this paper, we consider the design of a "squaring down" matrix which renders a system passive by using a linear combination of all collocated and non-collocated sensor/actuator pairs. The design uses experimental transfer functions and does not require the knowledge of the system model. The problem of finding the squaring down matrix is cast as a solution to a set of linear matrix inequalities (LMIs) subject to some additional performance considerations. The design procedure of the squaring down matrix assumes that velocity information is available from the sensors which is not generally the case. We show that the squaring down matrix can be implemented without the use of such velocity information. We provide experimental results gathered from the single link flexible beam setup in the C/sub La/MS laboratory at RPI to show that implementation of passive loops without velocity measurements provides very good results.

关键词： Feedback control Linear matrix inequalities Intelligent sensors control system synthesis Robust control Sensor systems Hydraulic actuators Transfer functions Laboratories Economic indicators

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The transversal and lattice multiple modulus algorithms for blind equalization of QAM signals

The transversal and lattice multiple modulus algorithms for ...

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MILCOM, Military Communications Conference

作者： R.A. Axford L.B. Milstein J.R. Zeidler RDTE Division Naval Command Control and Ocean Surveillance Center San Diego CA USA Department of Electrical and Computer Engineering University of California San Diego La Jolla CA USA

The most popular algorithm for blind equalization of QAM signals is the constant modulus algorithm (CMA). However, because the CMA cost function is not matched to constellations with signal points on multiple radii, CMA can exhibit excessive misadjustment for QAM signals. This paper develops an alternative to CMA, the multiple modulus algorithm (MMA), which is based on stochastic gradient minimization of a cost function that goes to zero at each radius of the QAM constellation. For the applicable QAM constellations, MMA exhibits significantly reduced misadjustment compared to CMA. A lattice implementation of MMA is also presented.

关键词： Lattices Blind equalizers Quadrature amplitude modulation Cost function Constellation diagram Stochastic processes Minimization methods Phase shift keying Oceans Surveillance

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A dual-mode algorithm for blind equalization of QAM signals: CADAMA

A dual-mode algorithm for blind equalization of QAM signals:...

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Asilomar Conference on Signals, Systems & computers

作者： R.A. Axford L.B. Milstein J.R. Zeidler RDTE Division Communications Department Naval Command Control and Ocean Surveillance Center San Diego CA USA Department of Electrical and Computer Engineering University of California San Diego La Jolla CA USA RDTE Division Communications Department Naval Command Control and Ocean Surveillance Center San Diego CA USA

The misadjustment exhibited by the constant modulus algorithm (CMA) can be excessive when it is used for blind equalization of QAM signals, thus degrading the performance of decision-directed carrier recovery algorithms. This paper introduces a hybrid blind equalization algorithm, the CMA-assisted decision adjusted modulus algorithm (CADAMA), that exhibits reductions in misadjustment on the order of 18 to 25 dB for higher order QAM constellations. CADAMA employs CMA to perform initial adjustment of the equalizer, and switches to decision adjusted modulus algorithm (DAMA) mode when the amplitude equalization has been sufficiently accomplished. DAMA is based on a phase-blind cost function that goes to zero at each ring of the QAM constellation.

关键词： Blind equalizers Quadrature amplitude modulation Decision feedback equalizers Cost function Switches Constellation diagram Histograms Communication system control Oceans Surveillance

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OPTIMUM FREQUENCY REUSE IN MOBILE TELEPHONY SYSTEMS

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INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS 1995年第3期8卷 185-190页

作者： KAZANTZAKIS, MG DEMESTICHAS, PP ANAGNOSTOU, ME National Technical University of Athens Computer Science Division Department of Electrical and Computer Engineering Heroon Polytechneiou 9 Zografou Athens 15773 Greece Michael G. Kazantzakii was born in Athens Greece in 1962. He received both the Diploma and Ph.D. Degree from the Electrical Engineering Department of the National Technical University of Athens in 1986 and 1992 respectively. During the period 1992–1993 he was a member of the Staff of the Hellenic Navy Research Centre working in the area of underwater acoustics. Since 1994 he has been a researcher at the National Technical University of Athens Department of Electrical Engineering and Computer Science Telecommunications Laboratory. His interests include data mobile and integrated services networks. Panagiotis P. Demestichas was born in Athens Greece in 1967. He received the Diploma in electrical engineering from the National Technical University of Athens (NTUA) Athens in 1993. At present he is a research assistant at NTUA working towards his Ph.D. dissertation. He participated in the BRITE/EURAM-EURATN and in the RACE-TOMQAT and MONET projects. His research interests are in the areas of broadband and mobile networks queueing theory algorithms and complexity theory. He is a Member of the Technical Chamber of Greece. Miltiades E. Anagnostou was born in Athens in 1958. He received the Electrical Engineers Diploma from the National Technical University of Athens (NTUA) in 1981. During the period 1981–1987 he was a teaching assistant at NTUA. In 1987 he received his Ph.D. in the area of computer networks. In 1987–1989 he served the Greek army in the Air Force Research and Development Center. In 1989–1991 he was a Lecturer and since 1991 he has been an Assistant Professor in the Computer Science Division Department of Electrical and Computer Engineering of the NTUA. He teaches courses on modern telecommunications formal specification of protocols stochastic processes and queueing theory. Since 1981 Dr. Anagnostou has been involved

The reason why cellular mobile telephony systems exist is that they allow frequency reuse. Dynamic allocation algorithms improve the network efficiency and the service quality. Dynamic allocation is closely related to the following instantaneous allocation problem: given a number of channels (frequencies), a cell structure and the number of calls to be accommodated in each cell, find the optimum allocation of channels to cells subject to restrictions concerning the distance of cells, where the same frequency can be reused. In this paper we formulate and solve this problem by showing that it can be reduced to a 0-1 programming problem. Finally we present results, and draw subsequent conclusions.

关键词： MOBILE TELEPHONY FREQUENCY ALLOCATION UMTS

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FAULT-TOLERANT ASSOCIATE MEMORIES

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SYSTEMS AND computerS IN JAPAN 1995年第7期26卷 1-12页

作者： FUJIWARA, E TANAKA, T Member Faculty of Engineering Tokyo Institute of Technology Tokyo Japan 152 Eui Fujiwara:received his B.S. and M.S. degrees in Electronics Engineering in 1968 and 1970 respectively and his Dr. of Eng. degree in 1981 all from Tokyo Institute of Technology. In 1970 he joined the NTT Musashino Electrical Communication Laboratories and engaged in developing PIPS-1 and PIPS-11 computer systems. In 1988 he joined the Department of Computer Science Tokyo Institute of Technology as an Associate Professor. In 1990 he became a full Professor. He was a Visiting Professor at the Center for Advanced Computer Studies the University of Southwestern Louisiana from June 1985 to July 1986. His current research interests include coding theory for computers fault-tolerant memories VLSI defect-toleranceand WSI systems. He is a co-author ofError Control Coding for Computer Systems(Prentice-Hall1989) EssentiaLF of Error-Correcting Coding Techniques (Academic Press 1990) and other books. Dr. Fujiwara received the Young Engineer Award from the I.E.I.C.E. in 1978 and the Teshima Memorial Research Award in 1991. He is a senior member of the IEEE and a member of the Information Processing Society Japan. Associate Member

Because of its capability of high-speed search, the associative memory (CAM) is expected to be used in a variety of information processing systems. In this paper, novel fault-tolerant techniques which are effective for on-line use are proposed for TLB which is an example of the application of CAM. First, fault and error models of the TLB consisting of the CAM part and the SRAM part are clarified. Then, the fault-tolerant techniques for these faults and errors, such as distance separable technique, cod-ing technique, simplified 1-out-of-n check and graceful degradation, are proposed. The distance separable technique which encodes the data stored in the CAM part is the one which masks the faulty CAM part and prevents errors from propagating to the subsequent circuits. The coding technique checks the one-to-one correspondence between the data in the CAM and those in SRAM by using the SEC-DED code with byte error detection capability, i.e., SEC-DED-SbED code, and at the same time it detects and corrects errors in the data stored in SRAM. The simplified 1-out-of-n check processes association errors. The graceful degradation gives a flag in the faulty memory section and prevents it from being used. The methods proposed in this paper are evaluated from area augmentation and error detection capability perspectives. The results show that the fault-tolerant TLB with 32 virtual address bits, 32 physical address bits and 128 entries gives single fault detection probability of nearly 99 percent with 28 percent area increase.

关键词： CAM TLB DISTANCE SEPARABLE TECHNIQUE CODING TECHNIQUE SIMPLIFIED 1-OUT-OF-N CHECK GRACEFUL DEGRADATION

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Silicon MOSFETs with very low microwave noise

Silicon MOSFETs with very low microwave noise

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Device Research Conference

作者： P.R. De La Houssaye C.E. Chang B. Offord R. Johnson P.M. Asbeck G.A. Garcia I. Lagnado Res. Dev. Test & Evaluation Div. Naval Command Control & Ocean Surveillance Centre San Diego CA USA Electrical and Computer Engineering Department University of California La Jolla CA USA Research Development Test and Evaluation Division Naval Command Control and Ocean Surveillance Center San Diego CA USA

Reports MOSFETs with noise figures as low as 0.9 dB at 2 GHz, the lowest achieved to date with Si FETs. The devices were fabricated in thin-film silicon-on-sapphire, with gate lengths (defined by optical lithography) drawn at 0.5 /spl mu/m. The devices employed T-gate structures, with extra added aluminum to minimize gate resistance. The microwave gain was high: f/sub max/ values were as high as 52 GHz (near record performance) for nMOS and 32 GHz far pMOS transistors; f/sub t/ values were 17 GHz and 13 GHz for nMOS and pMOS respectively.

关键词： Silicon MOSFETs Microwave devices Optical noise MOS devices Noise figure FETs Optical films Semiconductor thin films Thin film devices

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A simplified real frequency independent modal transformation for overhead line switching transient computations

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European Transactions on electrical Power 1995年第5期5卷 307-314页

作者： Papagiannis, G. Dokopoulos, P. Dipl.-Ing. Grigoris Papagiannis (1956) studied Electrical Engineering at the Department of Electrical Engineering of the Aristotle University of Thessaloniki/Greece. He received his Dipl.-Eng. degree in Electrical and Mechanical Engineering in 1979. Since 1981 he has been working as a Research Assistant at the Power Systems Laboratory of the Department of Electrical and Computer Engineering at the Aristotle University of Thessaloniki. His special interests are power systems analysis with emphasis in the computation of electromagnetic transients. (Aristotle University of Thessaloniki Department of Electrical and Computer Engineering Power Systems Laboratory P.O. Box 486 GR-54006 ThessalonikV Greece T +30 3 I/99 63 88 Fax +30 3 1/99 63 02) Prof. Petros Dokopoulos (1939) received his Dip1.-Eng. degree in Electrical and Mechanical Engineering from the National Technical University of AthendGreece in 1962 and his Ph. D. degree from the University of Brunswic W Germany in 1967. From 1962 to 1967 he was with the High Voltage Laboratory at the University of Brunswick from 1967 to 1974 with the Nuclear Research Center at Julichl Germany from I974 to I978 with the Joint European Torus. Since 1978 he is full Professor at the Department of Electrical Engineering at the Aristotle University of Thessalonikil Greece. He has worked as consultant with Brown Boveri Cie MannheidGermany Siemens AG ErlangedGermany Public Power Corporation of Greece and with the National Telecommunication Organisation of Greece. His scientific fields of interest include dielectrics power switches generators transmission systems and alternative energy sources. (Aristotle University of Thessaloniki Department of Electrical and Computer Engineering Power Systems Laboratory P.O. Box 486 GR-54006 Thessaloniki/Greece T + 3031/996321 Fax +3031/996302)

Modal transformation technique is a common tool for transmission line transient computations. A simplified modal decomposition of overhead transmission lines, suitable for time‐domain switching (up to 10⁵ Hz) transient computations, is proposed. By neglecting residual terms in the ZY matrix, transformation matrices are approximated as real and frequency independent. The resulting propagation constants remain unaffected from the line being transposed or not, although the existing asymmetries affect transformation matrices. The method can be extended for double circuit lines, provided they have the same configuration. Propagation characteristics, mode decoupling and travelling‐wave transmission effects have been investigated. Results are compared with those obtained from other methods in use. Copyright © 1995 John Wiley & Sons, Ltd.

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Nonlinear control system design via dynamic order reduction

Nonlinear control system design via dynamic order reduction

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IEEE Conference on Decision and control

作者： R. Ghanadan Center for Control Engineering and Computation Department of Electrical and Computer Engineering University of California Santa Barbara CA USA

In this paper we present a design scheme for output tracking of nonlinear systems that are subject to regular perturbations. We show that applications of singular perturbation theory to the input-output feedback linearization technique provides a systematic method to identify the slow "dominant" states and fast "negligible" states. Similar to the backstepping design technique, a suitable state variable is converted into a "control like" variable which in the steady state is forced to approach the desired tracking control law for the reduced order system. We show that this design achieves stable approximate tracking of reasonable reference trajectories for nonlinear systems that are "dominantly" minimum phase. The order of approximation can be arbitrarily improved by addition of correction terms in the control law. The main advantage of this approach is that the design is often performed for a much simpler model which is linear in the new control variable and describes the dominant part of the original system by ignoring some of the fast states that are forced to have little effect on the steady state performance.< >

关键词： Nonlinear control systems Nonlinear dynamical systems Nonlinear systems Steady-state Force control State feedback Linearization techniques Backstepping control systems Reduced order systems

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Tools and procedures for robust control of nonlinear systems

Tools and procedures for robust control of nonlinear systems

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IEEE Conference on Decision and control

作者： R.A. Freeman P.V. Kokotovic Center for Control Engineering and Computation Department of Electrical and Computer Engineering University of California Santa Barbara CA USA

We review some of the existing results on the Lyapunov design of robustly stabilizing feedback laws for uncertain nonlinear systems. Using the concept of a robust control Lyapunov function, we present robust backstepp... 详细信息

关键词： Robust control Nonlinear systems Lyapunov method Feedback control systems Force control Asymptotic stability Nonlinear control systems control engineering control engineering computing

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