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American Control Conference (ACC)

作者： A. J. Helmicki C. A. Jacobson C. N. Nett Department of Electrical Computer and Systems Engineering Raneselaer Poytechiic Institute Troy NY USA Department of Electrical and Computer Engineering Northeastern University Boston MA USA Control Systems Laboratory GE Corporate Research and Development Center Schenectady NY USA

This paper is a condensed version of recent work [17] wherein several fundamental practical concerns pertaining to the use of linear, time-invariant, distributed parameter systems as models of physical processes are investigated. In particular, it is argued here that certain common distributed parameter systems exhibit properties which make them unsuitable for use as plant models in the design of feedback compensation. Classes of distributed parameter systems exhibiting these properties are defined and are said to be ill-posed for use in feedback compensator design. The structure of these classes is investigated within an extremely general mathematical framework which imposes no a priori restrictions on the class of distributed parameter systems under consideration. Within this framework necessary and sufficient conditions are given which completely characterise the classes of ill-posed models and establish their equivalence. These conditions are concretely illustrated by way of applications to several well-known flexible structure models. Surprisingly, several of these models are determined to be ill-posed for use in feedback compensator design.

关键词： Distributed parameter systems Feedback Control systems Integral equations Distributed computing Control system synthesis Jacobian matrices Flexible structures Frequency Linearity

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Mean field theory and MT neurons

Mean field theory and MT neurons

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IEEE International Conference on systems, Man and Cybernetics

作者： A. Dobbins S.W. Zucker Computer Vision and Robotics Laboratory Department of Electrical Engineering McGill University Montreal QUE Canada Canadian Institute for Advanced Research Montreal QUE Canada

The problem of obtaining reliable estimates of the optic flow field and its variation is discussed. It is argued that circuitry in the middle temporal (MT) visual area is arranged to provide mean field approximations of the optical flow field, that is, the maximal neighborhood over which the local field can be well-approximated as uniform, parallel translation. In addition, the way the mean field approximation varies with neighborhood size and position is informative about the variation of the flow field. It is shown how receptive fields can be synthesized to represent the first-order differential information about the flow field. The same ideas are applicable to the binocular disparity vector field, and lead one to predict the existence of extrastriate neurons that are specialized for the local shear and stretch of the disparity and motion vector fields.< >

关键词： Neurons Image motion analysis Circuits computer architecture computer vision Robot vision systems Laboratories Shape Optical devices Retina

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Practical high speed gradient computation for harmonic balance simulators

Practical high speed gradient computation for harmonic balan...

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Microwave, MTT-S International Symposium

作者： J.W. Bandler Q.J. Zhang R.M. Biernacki Simulation Optimization Systems Research Laboratory and the Department of Electrical and Computer Engineering McMaster University Hamilton ONT Canada Optimization Systems Associates Inc. Dundas ONT Canada

The authors introduce a powerful computational concept called the future adjoint sensitivity technique (FAST). FAST is an expedient tool for gradient calculation in the harmonic balance environment. FAST combines the efficiency of the exact adjoint sensitivity technique with the simplicity of the conventional perturbation technique. The same concept carries over to a practically implementable Jacobian for fast harmonic balance simulation. FAST promises high-speed gradient evaluation essential for yield optimization of nonlinear monolithic microwave integrated circuits by general purpose of software. The features of FAST and its Jacobian extensions are illustrated by a mixer example and a frequency-doubler example.< >

关键词： Computational modeling Jacobian matrices Circuit simulation Voltage Nonlinear circuits Nonlinear equations Perturbation methods Vectors MMICs Microwave theory and techniques

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Efficient large-signal FET parameter extraction using harmonics

Efficient large-signal FET parameter extraction using harmon...

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Microwave, MTT-S International Symposium

作者： J.W. Bandler Q.J. Zhang S. Ye S.H. Chen Simulation Optimization Systems Research Laboratory and Department of Electrical and Computer Engineering McMaster University Hamilton ONT Canada Optimization Systems Associates Inc. Dundas ONT Canada

The authors present a novel approach to large-signal nonlinear parameter extraction of GaAs metal-semiconductor field-effect transistor (MESFET) devices measured under harmonic conditions. Powerful nonlinear adjoint-based optimization simultaneously processes multibias, multi-power-input, multi-fundamental-frequency excitations and multiharmonic measurements to reveal the parameters of the intrinsic FET. One test successfully processed 111 error functions of 20 model parameters. The technique was implemented in a program called HarPE (harmonic balance driven model parameter extractor).< >

关键词： Parameter extraction Microwave FETs Power measurement Power system harmonics Computational modeling Data mining Circuits Voltage Gallium arsenide MESFETs

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Yield optimization of nonlinear circuits with statistically characterized devices

Yield optimization of nonlinear circuits with statistically ...

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Microwave, MTT-S International Symposium

作者： J.W. Bandler Q.J. Zhang J. Song R.M. Biernacki Simulation Optimization Systems Research Laboratory and the Department of Electrical and Computer Engineering McMaster University Hamilton ONT Canada Optimization Systems Associates Inc. Dundas ONT Canada

A comprehensive treatment of yield optimization of nonlinear microwave circuits with statistically characterized devices is proposed. The authors fully exploit advanced techniques of a one-sided l/sub 1/ circuit centering with gradient approximations and efficient harmonic balance simulation with exact Jacobians. Multidimensional statistical distributions of the intrinsic and parasitic parameters of field-effect transistors are fully handled. Yield is driven from 25% to 61% for a frequency doubler design having 34 statistically toleranced parameters. The yield of a small-signal amplifier is increased from 36% to 68%.< >

关键词： Nonlinear circuits Circuit simulation Microwave devices Microwave circuits Design optimization Jacobian matrices Integrated circuit yield Robustness Microwave FETs Computational modeling

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Combined Discrete/Normal Statistical Modeling of Microwave Devices

Combined Discrete/Normal Statistical Modeling of Microwave D...

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European Conference on Microwave

作者： J.W. Bandler R.M. Biernack S.H. Chen J.F. Loman M.L. Renault Q.J. Zhang Simulation Optimization Systems Research Laboratory Department of Electrical and Computer Engineering McMaster University Hamilton Canada Optimization Systems Associates Inc. P.O. Box 8083 Dundas Ontario Canada L9H 5E7 Simulation Optimization Systems Research Laboratory Department of Electrical and Computer Engineering McMaster University Hamilton Canada L8S 4L7. Optimization Systems Associates Inc. Dundas ONT Canada

This paper deals with statistical characterization of the equivalent circuit parameters for microwave FET devices. The statistics are derived from the S-parameters measured for a sample of devices. The use of a multidimensional normal distribution seems justified for most parameters. For parameters exhibiting sample distributions substantially different from normal we propose a combined discrete/normal approach that can preserve the means, standard deviations, correlations and marginal distributions derived from the sample. This provides enhanced accuracy of the model while retaining the simplicity of the normal distribution. The problem of the size of the sample is also addressed in terms of confidence levels and confidence intervals.

关键词： Microwave devices Equivalent circuits Gaussian distribution Scattering parameters Multidimensional systems Parameter extraction Histograms Microwave FETs Circuit simulation Statistical distributions

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Kerr electro-optic field mapping measurements in liquid nitrogen

Kerr electro-optic field mapping measurements in liquid nitr...

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Conference on electrical Insulation and Dielectric Phenomena, (CEIDP)

作者： A. Kanematsu M. Zahn Dept. of Electr. Eng. & Comput. Sci. MIT Cambridge MA USA Department of Electrical Engineering and Computer Science Laboratory for Electromagnetic and Electronic Systems High Voltage Research Laboratory Massachusetts Institute of Technology Cambridge MA USA

Kerr electrooptic field mapping measurements were made in liquid nitrogen at 70 psi and -177 degrees C. A sensitive measurement technique was used whereby a small-signal AC voltage was superimposed on a DC level. The nonlinear optical effect then gave an optical signal with a DC level and AC harmonic at the same frequency as the AC voltage. The amplitude of the AC optical signal was proportional to the local electric field and was measured with a lock-in amplifier. For 6330-nm-wavelength light the Kerr constant was measured to be B approximately=10/sup -16/ m/V/sup 2/. Steady-state electric fields between parallel stainless steel electrodes of gap 7 mm and area 31.6 cm/sup 2/ were shown to be essentially uniform for field strengths up to 90 kV/cm with no significant space charge distortion. The DC voltage-current characteristic was also measured and found to be nonohmic, reaching constant current of approximately=13 nA over the voltage range of approximately=30-60 kV.< >

关键词： Nitrogen Voltage Nonlinear optics Stimulated emission Optical distortion Optical sensors Electric fields Pressure measurement Measurement techniques Frequency

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Portable parallel logic and fault simulation

Portable parallel logic and fault simulation

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IEEE International Conference on computer-Aided Design

作者： R.B. Mueller-Thuns D.G. Saab R.F. Damiano J.A. Abraham Computer Systems Group Coordinated Science Laboratory University of Illinois Urbana-Champaign Urbana IL USA IBM Thomas J. Watson Research Center Yorktown Heights NY USA Department of Electrical and Computer Engineering University of Texas Austin Austin TX USA

Consideration is given to the use of general-purpose multiprocessors for various simulation tasks. The aims of the work are to define a general framework for the parallel simulation of digital systems and to develop and evaluate tools for logic and fault simulation that have a good cost-performance ratio. Specifically, a novel partitioning approach is introduced and used as the basis for the parallel logic and fault simulation of synchronous gate-level designs. Performance experiments with prototype implementations on a message passing and a shared memory machine give promising results, in particular for fault simulation.< >

关键词： Logic Computational modeling Very large scale integration computer simulation Switches Circuit faults Circuit simulation Discrete event simulation Digital systems High performance computing

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Two Adaptive Control Structures of Robot Manipulators

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IFAC Proceedings Volumes 1989年第10期22卷 371-377页

作者： B.J. Oh M. Jamshidi H. Seraji Automation Technologies Department Korea Electronics and Telecomm Research Institute Daedog Danji. P.O. Box 8. Daejeon. Korea CAD Laboratory for Systems/Robotics. Department of Electrical and Computer Engineering University of New Mexico. Albuquerque. New Mexico 87131. USA Jet Propulsion Laboratory. California Institute of Technology. 4800 Oak Grove Drive. Pasadena. California 91109. USA

This paper proposes two simple schemes for adaptive control of robot manipulator, to achieve trajectory tracking. The state feedback controller consists of feedforward from the reference position trajectory, feedback from the actual trajectory, and an auxiliary input. The feedforward/feedback controller is different from the state feedback controller in that it consists of feedforward from the reference position, velocity, and acceleration trajectory based on “inverse” dynamics of robot manipulator. The feedforward and feedback gains and the auxiliary input are adapted using adaptive control theory based on Lyapunov's direct method, and using only the local information of the corresponding joint. The proposed control schemes are computationally fast and do not require a priori knowledge of the parameter of the manipulator or the payload. Simulation results are presented in support of the proposed schemes.

关键词： Adaptive Control Decentralized Adaptive Control Robot Manipulator Feedforward Feedback

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BOUNDARY-VALUE PROBLEMS IN ELECTROFLUIDIZED AND MAGNETICALLY STABILIZED BEDS

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CHEMICAL engineering COMMUNICATIONS 1988年第1期67卷 181-204页

作者： MOISSIS, AA ZAHN, M High Voltage Research Laboratory Laboratory for Electromagnetic and Electronic Systems Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge Massachusetts 02139

The stress balance boundary condition at the free surface of a one dimensional electrofluidized or magnetically stabilized bed is reviewed. Conditions for zero interfacial force balance at the top of the bed are investigated. For the case of a uniformly fluidized bed, it is shown that a nonzero particle collision pressure is necessary for a force free bed surface. For the case where the collision pressure is neglected, it is shown that the electrofluidized or magnetically stabilized bed must be nonuniform at equilibrium. Stability criteria for a semi-infinite bed show that a critical field strength is necessary for stabilization. Below this critical condition the bed is convectively unstable. The temporal and spatial responses of a stabilized bed to small signal variations in superficial gas velocity, electrode position, and applied potential are calculated. Specific attention is directed to sinusoidal time variations in superficial gas velocity, where at low frequencies a standing wave character results for the fluidized bed variables.

关键词： Electrofluidization Magnetically stabilized beds Fiuidization Stabilization Boundary value problems.

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