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FAST ALGORITHMS FOR ESTIMATING LOCAL IMAGE PROPERTIES

computer VISION GRAPHICS AND IMAGE PROCESSING 1983年第3期21卷 368-382页

作者： BURT, PJ Image Processing Laboratory Electrical Computer and Systems Engineering Department Rensselaer Polytechnic Institute Troy New York 12181

A common task in image analysis is that of measuring image properties within local windows. Often usefulness of these property estimates is determined by characteristics of the windows themselves. Critical factors include the window size and shape, and the contribution the window makes to the cost of computation, A highly efficient procedure for computing property estimates within Gaussian-like windows is described. Estimates are obtained within windows of many sizes simultaneously.

关键词： IMAGE PROCESSING

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REAL-TIME ADAPTIVE-CONTROL OF THE PERMANENT-MAGNET SYNCHRONOUS MOTOR

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IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS 1991年第4期27卷 706-734页

作者： SEPE, RB LANG, JH Laboratory for Electromagnetic and Electronic Systems Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge MA USA

This paper develops a fully digital adaptive velocity controller for the permanent-magnet synchronous motor. The critical issues addressed during the development of this controller include discretization and global linearization of the nonlinear motor system, nonlinearities in the inverter, nonminimum phase behavior due to sampling, sampling rate restrictions, robust mechanical state estimation, persistant excitation of the mechanical states, mechanical parameter estimation and validation of these estimates, and unmodeled dynamics. The resulting adaptive controller is implemented in real time using a computer system based on the Motorola 68020 microprocessor. Experimental results demonstrate that the adaptive controller maintains the desired control over velocity in the presence of varying mechanical parameters.

关键词： Adaptive control Programmable control Velocity control Synchronous motors Control systems Sampling methods State estimation Digital control Nonlinear control systems Control nonlinearities

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DISTRIBUTED DETECTION WITH CONSULTING SENSORS AND COMMUNICATION COST

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IEEE TRANSACTIONS ON AUTOMATIC CONTROL 1992年第9期37卷 1398-1405页

作者： THOMOPOULOS, SCA OKELLO, NN Department of Electrical and Computer Engineering Decision and Control Systems Laboratory Pennslyvania State University University Park PA USA

The problem of distributed detection with consulting sensors in the presence of communication cost associated with any exchange of information (consultation) between sensors is considered. We consider a system of two sensors, S1 and S2, in which S1 is the primary sensor responsible for the final decision u0, while S2 is a consulting sensor capable of relaying its decision u2 to S1 when requested by S1. In the scenario that is considered, the final decision u0 is based either on the raw data available to S1 only, or it may, under certain request conditions, also take into account the decision u2 of sensor S2. Random and nonrandom request schemes are analyzed and numerical results are presented and compared for Gaussian and slow-fading Rayleigh channels. For each decision making scheme, an associated optimization problem is formulated whose solution is shown to satisfy certain a priori set design criteria that we consider essential for sensor fusion.

关键词： Costs Sensor fusion Control systems Sensor systems Frequency Communication system control Servomechanisms Steady-state Polynomials Error correction

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COUETTE CHARGER FOR MEASUREMENT OF EQUILIBRIUM AND ENERGIZATION FLOW ELECTRIFICATION PARAMETERS - APPLICATION TO TRANSFORMER INSULATION

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IEEE TRANSACTIONS ON electrical INSULATION 1988年第1期23卷 159-176页

作者： LYON, DJ MELCHER, JR ZAHN, M Department of Electrical Engineering and Computer Science Laboratory for Electromagnetic and Electronic Systems Massachusetts Institute of Technology Cambridge MA USA

The fluid under test (e.g. transformer oil) fills the annulus between coaxial circular cylinders that are covered by the solid of interest (e.g., metal or oil-impregnated paper backed by metal). The inner cylinder can rotate at speeds giving controlled laminar and turbulent flows (for fluids as viscous as transformer oil). This relatively compact apparatus allows for flexibility in testing liquids, trace impurities, and solid insulation without involving large amounts of material. By virtue of the reentrant flow, it acts like a pipe of infinite length and thus provides for the measurement of basic electrification parameters even in highly insulating systems, where the electrical development length for a pipe flow system is likely to be longer than the practical length of a test section. By sampling the charge entrained in the azimuthal flow at a sufficiently slow rate, equilibrium parameters can be deduced.

关键词： insulating oils insulation testing transformer insulation Couette charger azimuthal flow coaxial circular cylinders electrification parameters energization flow electrification parameters equilibrium parameters reentrant flow solid insulation trace impurities transformer insulation transformer oil turbulent flows Coaxial components Current measurement Energy measurement Fluid flow control Fluid flow measurement Insulation testing Materials testing Oil insulation Power transformer insulation Solids

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FLOW-INDUCED CHARGE ACCUMULATION IN THIN INSULATING TUBES

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IEEE TRANSACTIONS ON electrical INSULATION 1988年第1期23卷 103-115页

作者： GASWORTH, SM MELCHER, JR ZAHN, M Department of Electrical Engineering and Computer Science Laboratory for Electromagnetic and Electronic Systems Massachusetts Institute of Technology Cambridge MA USA

The flow of semi-insulating liquids through insulating tubes can induce the accumulation of surface charge at the liquid-tube interface and generate electric fields intense enough to jeopardize the insulation. The space-time evolution of charge and fields is studied theoretically and experimentally for conditions typical of liquid-cooled power distribution equipment. With the experiment arranged so that charge generation is dominantly upstream of the insulating section, it is found that the absolute prediction of the space-time evolution of the electric field in the region surrounding the tube (and the field in the wall of the tube where damage is done) correlates with field transients measured at two locations outside the tube.

关键词： insulating materials insulation testing electric fields field transients liquid-cooled power distribution equipment liquid-tube interface semi-insulating liquids space-time evolution surface charge thin insulating tubes Conductors Dielectric liquids Dielectrics and electrical insulation Ducts Electromagnetic fields Fluid flow Laboratories Power distribution Space technology Switches

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Fast algorithms for basic processing and analysis operations on block-represented binary images

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PATTERN RECOGNITION LETTERS 1996年第14期17卷 1437-1450页

作者： Spiliotis, IM Mertzios, BG Automatic Control Systems Laboratory Department of Electrical and Computer Engineering. Democritus University of Thrace Xanthi 67100 Greece

This paper describes a binary image representation scheme, called Image Block Representation and presents new algorithms for a number of basic binary image processing and analysis operations, which are rapidly implemented on block-represented binary images. The main purpose of the Image Block Representation is to provide an efficient binary image representation that permits the execution of operations on image areas instead of image points.

关键词： image block representation image normalization image measurements logic operations

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ELECTROMAGNETIC IMAGING OF UNDERGROUND TARGETS USING CONSTRAINED OPTIMIZATION

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IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING 1995年第3期33卷 551-561页

作者： CHATURVEDI, P PLUMB, RG Department of Electrical Engineering and Computer Science Radar Systems and Remote Sensing Laboratory University of Kansas Lawrence KS USA

Several high-frequency electromagnetic techniques have been used in recent years to detect and identify buried objects. Post-processing of the collected data is performed in many of these techniques to obtain high-quality images of buried targets, Accurate reconstructions of the target's constitutive parameters can be obtained by casting the imaging problem in terms of an inverse electromagnetic scattering problem, A number of techniques have been put forth recently to invert the electromagnetic data to obtain such images, In this paper, we use a frequency-domain Born iterative method to reconstruct images of shallow targets, The Born iterative technique requires successive solutions to a forward scattering problem followed by an inverse scattering problem at each iteration step, We use a finite-difference time domain (FDTD) algorithm to solve the forward scattering problem and constrained optimization for the inverse problem. Two-dimensional simulated data for several canonical objects buried in the ground are obtained using the FDTD technique, The same FDTD code is also used in calculating the Green's function required for solving the constrained optimization problem, Lossy, inhomogeneous ground models are used in several simulations to illustrate the use of this technique for practical situations, The inversion process can be used to reconstruct images for many realistic dielectric contrasts for which a linear Born approximation fails. Moreover, it is also shown that a small number of measurements results in accurate reconstructions with this technique, Use of multiple frequencies is also investigated.

关键词： Image reconstruction Finite difference methods Time domain analysis Electromagnetic scattering Buried object detection Inverse problems Constraint optimization Casting Iterative methods Iterative algorithms

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DETECTION OF BROKEN ROTOR BARS IN INDUCTION-MOTORS USING STATE AND PARAMETER-ESTIMATION

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IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS 1992年第3期28卷 702-709页

作者： CHO, KR LANG, JH UMANS, SD Department of Electrical Engineering and Computer Science Laboratory for Electromagnetic and Electronic Systems Massachusetts Institute of Technology Cambridge MA USA

This paper studies the detection of broken rotor bars in induction motors. The hypothesis on which detection is based is that the apparent rotor resistance of an induction motor will increase when a rotor bar breaks. Here, the apparent rotor resistance is that in the balanced steady-state single-phase electrical model of an induction motor. To detect broken rotor bars, measurements of stator voltage, stator current, stator excitation frequency, and rotor velocity are taken over a small range of velocity. These measurements are processed by a near-least-square-error estimator to produce estimated motor states and parameters. In particular, rotor resistance is estimated and compared with its nominal value to detect broken rotor bars. As part of this estimation process, it is necessary to compensate for the thermal variation in rotor resistance. The broken-rotor-bar detector is evaluated experimentally using one stator and three rotors from identical 3-hp induction motors. In one rotor, a bar is broken by milling into the rotor. The apparent rotor resistance, as estimated, is clearly greater for the rotor with the broken bar.

关键词： Rotors Bars Induction motors Stators Electric resistance electrical resistance measurement State estimation Thermal resistance Steady-state Current measurement

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POSITIVE REALNESS PRESERVING MODEL-REDUCTION WITH H-INFINITY NORM ERROR-BOUNDS

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IEEE TRANSACTIONS ON CIRCUITS AND systems I-FUNDAMENTAL THEORY AND APPLICATIONS 1995年第1期42卷 23-29页

作者： CHEN, X WEN, JT Control Laboratory for Mechanical Structures Department of ElectricalComputerand Systems Engineering Rensselaer Polytechnic Institute Troy NY USA

Many physical systems that occur in applications are naturally passive, for example, mechanical systems with dual sensors and actuators, and electrical circuits with passive components. Taking advantage of this property, many controller schemes have been proposed with the property that the controller is strictly positive real. Due to design and implementation considerations, the plant or the controller may need to be approximated by a lower-order system. It is highly desirable for the reduced-order system to also possess the positive realness property to guarantee that the resulting closed-loop system remains stable. Motivated by this problem, this paper considers the general model-reduction problem for a positive real system under the constraint that the reduced system is also positive real. We present a solution based on the balanced stochastic truncation. When the higher-order system is strictly positive real, we derive an H(infinity) norm bound on the approximation error. We also consider alternate approaches of approximating the spectral factors with associated H(infinity) norm error bounds. An example is included to show the efficacy of this method and comparison with other approaches.

关键词： Reduced order systems Mechanical sensors Actuators Stochastic processes Binary search trees Sensor systems and applications Circuits Control systems Approximation error Riccati equations

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STATE OBSERVERS FOR VARIABLE-RELUCTANCE MOTORS

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IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS 1990年第2期37卷 133-142页

作者： LUMSDAINE, A LANG, JH Department of Electrical Engineering and Computer Science Laboratory for Electromagnetic and Electronic Systems Massachusetts Institute of Technology Cambridge MA USA

A sequence of progressively more complex state observers, each driven by measurements of phase voltages and currents, is developed for variable-reluctance motors. For the simpler observers, the exponential stability of their error dynamics in a neighborhood of the origin is proved. For all observers, the results of numerical or physical experiments are provided to demonstrate the globally stable error dynamics. In several of the physical experiments, rotor position is estimated to better than one part in 50000 of a revolution.< >

关键词： Rotors Traction motors Stators Voltage Observers Current measurement Phase measurement Magnetic flux Saturation magnetization Inductance

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