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American control Conference (ACC)

作者： D. Krupp Y.B. Shtessel Guidance and Control Division NASA Marshall Space Flight Center AL USA Department of Electrical and Computer Engineering University of Alabama Huntsville AL USA

Sliding mode control systems are valued for their robust accommodation of uncertainties and their ability to reject disturbances. In this paper, a design methodology is proposed to eliminate the chattering phenomenon affecting sliding mode controlled plants with input unmodeled actuator dynamics of second order or greater. The proposed controller design is based on the relative degrees of the plant and the unmodeled actuator dynamics and ranges of the uncertainties of the plant and actuator. The controller utilizes the pass filter characteristics of the physical actuating device to provide a smoothing effect on the discontinuous control signal rather than introducing any artificial dynamics into the controller design thus eliminating chattering in the system's output response.

关键词： Sliding mode control Actuators control systems Uncertainty Robust control Design methodology Dynamic range Filters Smoothing methods Signal design

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Multiplexing VBR video and training sequences on wireless fading channels

Multiplexing VBR video and training sequences on wireless fa...

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MILCOM, Military Communications Conference

作者： F. Freiha K. Chandra V. Mehta C. Thompson Center for Advanced Computation and Telecommunication Department of Electrical and Computer Engineering University of Massachusetts Lowell Lowell MA USA Optical Networking Group Lucent Technologies Inc. Andover MA USA

A time slotted multiple access scheme that shares bandwidth between source and training signals is proposed for the transmission of variable bit rate (VBR) video signals over non-ideal channels. The error performance is examined using finite state Markov chains that model both the VBR source traffic and the time variation of fading channels. The characteristic time-scale of the fade duration, the step-size parameter of the LMS equalizer training algorithm, and the number of training sequences allocated per time slot jointly influence the error performance. The consideration of the physical layer characteristics in the design of higher layer protocols enhances the performance of conventional application layer based preventive and reactive error control schemes. Simulation results for fast and slow fading channels show that the proposed channel access scheme can lead to an order of magnitude decrease in the bit error ratio if the combination of training overhead and step-size parameter are chosen judiciously with respect to the fading time-scale. In addition, the multiplexing efficiency of VBR encoded video is shown to be useful for limiting the channel access delays when training overhead is increased.

关键词： Fading Video sharing Bandwidth Bit rate Traffic control Least squares approximation Equalizers Physical layer Access protocols Error correction

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On Hopf bifurcations in indirect field oriented control of induction motors: designing a robust PI controller

On Hopf bifurcations in indirect field oriented control of i...

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IEEE Conference on Decision and control

作者： A.S. Bazanella R. Reginatto R. Valiati Department of Electrical Engineering Universidade Federal do Rio Grande do Sul Porto Alegre Rio Grande do Sul Brazil Center for Control Engineering and Computation University of California슠Santa Barbara Santa Barbara CA USA

In this paper we analyze the occurrence of Hopf bifurcations in indirect field-oriented control of induction motors and derive guidelines for setting the PI speed loop controller in order to keep the bifurcations far ... 详细信息

ISBN: (纸本)0780352513

关键词： Bifurcation Induction motors Robust control Velocity control Torque control Rotors Guidelines Equations Robust stability Error correction

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A hamiltonian approach to the eikonal equation 2nd

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2nd International Workshop on Energy Minimization Methods in computer Vision and Pattern Recognition, EMMCVPR 1999

作者： Siddiqi, Kaleem Tannenbaum, Allen Zucker, Steven W. School of Computer Science and Center for Intelligent Machines McGill University McGill University 3480 University Street MontréalPQH3A 2A7 Canada Department of Electrical and Computer Engineering University of Minnesota University of Minnesota 200 Union Street S. E MinneapolisMN55455 United States Department of Computer Science and Center for Computational Vision and Control Yale University Yale University New HavenCT06520-8285 United States

ISBN: (纸本)3540662944

The eikonal equation and variants of it are of significant interest for problems in computer vision and image processing. It is the basis for continuous versions of mathematical morphology, stereo, shapefrom-shading and for recent dynamic theories of shape. Its numerical simulation can be delicate, owing to the formation of singularities in the evolving front, and is typically based on level set methods introduced by Osher and Sethian. However, there are more classical approaches rooted in Hamiltonian physics, which have received little consideration in the computer vision literature. Here the front is interpreted as minimizing a particular action functional. In this context, we introduce a new algorithm for simulating the eikonal equation, which offers a number of computational advantages over the earlier methods. In particular, the locus of shocks is computed in a robust and efficient manner. We illustrate the approach with several numerical examples. © Springer-Verlag Berlin Heidelberg 1999.

关键词： Mathematical morphology

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Performance of VBR video with equalization on wireless fading channels

Performance of VBR video with equalization on wireless fadin...

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Seamless Interconnection for Universal Services. Global Telecommunications Conference. GLOBECOM'99. (Cat. No.99CH37042)

作者： F. Freiha K. Chandra V. Mehta C. Thompson Center for Advanced Computation and Telecommunications Department of Electrical and Computer Engineering University of Massachusetts Lowell Lowell MA USA Optical Networking Group Lucent Technologies Bell Laboratories North Andover MA USA

The error and delay performance of variable bit rate (VBR) video transmission over non-ideal channels is examined using equalization schemes. The temporal correlation features of the fading signal and the source video are modeled using finite state Markov chains. The source and training signals are multiplexed using a time slotted multiple access scheme. For slow-fading channels, the characteristic time-scale of the fade durations, the step-size parameter of the LMS equalizer training algorithm, and the number of training sequences allocated per time slot are found to jointly influence error performance. Simulation results show that the proposed channel access scheme can lead to an order of magnitude decrease in the bit error ratio if the combination of training overhead and step-size parameter are chosen judiciously with respect to the fading time-scale. In addition, the multiplexing efficiency of VBR encoded video is shown to be useful for limiting the channel access delays when the training overhead is increased.

关键词： Fading Error correction Bit rate Delay Time division multiple access Bandwidth Forward error correction Equalizers Layout Video sharing

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Quantum computation with quantum dots and terahertz cavity quantum electrodynamics

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Physical Review A 1999年第5期60卷 3508-3508页

作者： Mark S. Sherwin Atac Imamoglu Thomas Montroy Department of Physics University of California at Santa Barbara Santa Barbara California 93106 Center for Quantum Computation and Coherence in Nanostructures Quantum Institute University of California at Santa Barbara Santa Barbara California 93106 Department of Electrical and Computer Engineering University of California at Santa Barbara Santa Barbara California 93106

A quantum computer is proposed in which information is stored in the two lowest electronic states of doped quantum dots (QD’s). Many QD’s are located in a microcavity. A pair of gates controls the energy levels in each QD. A controlled-NOT (C-NOT) operation involving any pair of QD’s can be effected by a sequence of gate-voltage pulses which tune the QD energy levels into resonance with frequencies of the cavity or a laser. The duration of a C-NOT operation is estimated to be much shorter than the time for an electron to decohere by emitting an acoustic phonon.

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Robust controller design for RTP system using structured uncertainty approach

Robust controller design for RTP system using structured unc...

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SICE Annual Conference

作者： Sang Kyung Lee Jong Hae Kim Do Chang Oh Hong Bae Park Department of Computer Applied Control Doowon Technical College Ansung South Korea Sensor Technology Research Center Kyungpook National University Taegu South Korea Department of Information Electronics and Communication Engineering Konyang University South Korea School of Electronic and Electrical Engineering Kyungpook National University Taegu South Korea

In this paper, we propose an robust controller design of rapid thermal processing (RTP) system using the structured uncertainty approach. Using the weighted mixed sensitivity function, we solve the robust stability problem against disturbance and temperature variation, and design a /spl mu/ controller using the curve fitting method against structured uncertainty. Finally, the simulation results are proposed to show the validity of the proposed method.

关键词： Robust control control systems Uncertainty Temperature control Robust stability Thermal stresses Communication system control Temperature sensors Ovens Semiconductor device modeling

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Robust and non-fragile H/sub /spl infin// control of parameter uncertainties time-varying delay systems

Robust and non-fragile H/sub /spl infin// control of paramet...

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SICE Annual Conference

作者： Jong Hae Kim Sang Kyung Lee Hong Bae Park Sensor Technology Research Center Kyungpook National University Taegu South Korea Department of Computer Applied Control Doowon Technical College Ansung South Korea School of Electronic and Electrical Engineering Kyungpook National University Taegu South Korea

This paper describes the synthesis of robust and non-fragile H/sup /spl infin// state feedback controllers for linear systems with time delay and parameter uncertainties, and static state feedback controller with multiplicative uncertainty. The sufficient condition of controller existence, the design method of robust and non-fragile H/sup /spl infin// state feedback controller, and the measure of non-fragility in controller are presented. Also, using some changes of variables and Schur complements, the obtained sufficient condition can be rewritten as an linear matrix inequality form in terms of transformed variables. Therefore, the obtained robust and non-fragile H/sup /spl infin// controller guarantees the asymptotic stability and disturbance attenuation of the closed loop system in spite of controller gain variations within a degree.

关键词： Robustness Robust control State feedback control system synthesis Linear feedback control systems Sufficient conditions control systems Linear systems Delay effects Uncertain systems

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Observer-based fuzzy H/sup /spl infin// control for uncertain nonlinear systems with time delays

Observer-based fuzzy H/sup /spl infin// control for uncertai...

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American control Conference (ACC)

作者： Kap Rai Lee Jong Hae Kim Eun Tae Jeung Han O Yun Hong Bae Park Department of Computer Applied Control Doowon Technical College Ansung Gyeonggi South Korea Sensor Technology Research Center Kyungpook National University Taegu South Korea Department of Control and Instrument Engineering Changwon NatE28099l University Kyungnam South Korea Department of Electronics Kumi College Kumi Gyeongbuk South Korea School of Electronic and Electrical Engineering Kyungpook National University Taegu South Korea

ISBN: (纸本)0780349903

This paper presents the problem of observer-based fuzzy H/sup /spl infin// control for a class of uncertain nonlinear systems with time-varying delayed systems on the basis of Takagi-Sugeno fuzzy model. First, we design a fuzzy observer such that destination error system is globally, exponentially stable. Next, we design a fuzzy H/sup /spl infin// controller such that the closed loop system is globally, exponentially stable and achieves L/sub 2/ gain performance. The fuzzy control systems utilize the concept of the so-called parallel distributed compensation. A sufficient condition for the existence of robust fuzzy H/sup /spl infin// controllers and observers are given in terms of linear matrix inequalities (LMIs). The control gains can also be directly obtained from the LMI solutions.

关键词： Fuzzy control Fuzzy systems Nonlinear control systems Nonlinear systems Time varying systems Delay systems Takagi-Sugeno model control systems Closed loop systems Performance gain

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Bas-relief ambiguity

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International Journal of computer Vision 1999年第1期35卷 33-44页

作者： Belhumeur, Peter N. Kriegman, David J. Yuille, Alan L. Center for Comp. Vision and Control Dept. of Electrical Engineering Yale University New Haven CT 06520 United States Beckman Institute Department of Computer Science Univ. of Illinois Urbana-Champaign Urbana IL 61801 United States Smith-Kettlewell Eye Res. Institute San Francisco CA 94115 United States

When an unknown object with Lambertian reflectance is viewed orthographically, there is an implicit ambiguity in determining its 3-d structure: we show that the object's visible surface f(x, y) is indistinguishable from a `generalized bas-relief' transformation of the object's geometry, f¯(x, y) = λf(x, y)+μx+vy, and a corresponding transformation on the object's albedo. For each image of the object illuminated by an arbitrary number of distant light sources, there exists an identical image of the transformed object illuminated by similarly transformed light sources. This result holds both for the illuminated regions of the object as well as those in cast and attached shadows. Furthermore, neither small motion of the object, nor of the viewer will resolve the ambiguity in determining the flattening (or scaling) λ of the object's surface. Implications of this ambiguity on structure recovery and shape representation are discussed.

关键词： Object recognition

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