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ZERO LOCUS OF A BEAM WITH VARYING SENSOR AND ACTUATOR LOCATIONS

JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 1993年第1期16卷 21-25页

作者： LEE, YJ SPEYER, JL UNIV TEXAS DEPT AEROSP ENGN & ENGN MECHAUSTINTX 78712

The nonrational transfer function of an important component of a flexible structure, the beam, is analyzed. The true pattern of zeros of that transfer function is investigated as a function of sensor and actuator separation. Translational displacement sensors are used for two cases in which a force input and a moment input are separately applied at one end of the beam. Contrary to general opinion, zeros do not simply approach the origin along the real axis of the s plane as the sensor is moved away from the point of force/moment application. When the displacement sensor is located at a certain point, the first pair of zeros on the real axis of the s plane arrive at the origin and cancel the rigid-body mode. The location of the translational displacement sensor on the beam at which the rigid-body mode of the beam is unobservable is analyzed as the center of percussion and is uniquely located for each case. If the sensor is moved beyond such a point, a pair of zeros appear on the imaginary axis and move away from the origin along the imaginary axis of the s plane. Finally, the zero migration associated with an angular displacement sensor is briefly considered and compared with the zero migration associated with the translational displacement sensor.

关键词： Actuators Displacement Sensor Flexible Structures Taylor Series Beam (Structures) Finite Element Method Bernoulli Euler Beams distributed parameter system Mathematical Models Numerical Analysis

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ELECTROCHEMICAL IMPEDANCE OF A BURIED LARGE STRUCTURE

ELECTROCHEMICAL IMPEDANCE OF A BURIED LARGE STRUCTURE

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SYMP ON ELECTROCHEMICAL IMPEDENCE : ANALYSIS AND INTERPRETATION

作者： SUDO, S HARUYAMA, S Tohoku Electric Power Co Inc Miyagi Japan

ISBN: (纸本)0803118619

The polarization resistance and electrochemical impedance for a two-electrode cell consisting of a buried metallic structure and a small nonpolarizable disk electrode has been discussed considering the distribution of the signal current. Since interfacial impedance decreases with increasing ac frequency, the electrochemical impedances at high and low frequencies correspond to those for the primary and secondary current distributions respectively. The complex plane plot of the electrochemical impedance of a buried structure measured with the probe exhibits a semicircle or semi-ellipse depending on the structure, the intercept of which is not proportional on the real axis to the polarization resistance. The impedance diagrams for a buried structure in the presence of local corrosion deviate from those in the absence of local corrosion below a certain frequency, which is determined by the distance between the local corrosion site and the probe electrode. This threshold frequency serves as a reliable tool for detecting the location of the local corrosion of a buried structure.

关键词： BURIED STRUCTURE POLARIZATION RESISTANCE PRIMARY CURRENT DISTRIBUTION SECONDARY CURRENT DISTRIBUTION CORROSION MONITORING MEASURING AREA LOCAL CORROSION distributed parameter system ELECTROCHEMICAL IMPEDANCE

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OBSERVER DESIGN AND SENSOR-LOCATION IN distributed-parameter BIOREACTORS

OBSERVER DESIGN AND SENSOR-LOCATION IN DISTRIBUTED-PARAMETER...

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3RD SYMP ON DYNAMICS AND CONTROL OF CHEMICAL REACTORS, DISTILLATION COLUMNS AND BATCH PROCESSES ( DYCORD PLUS 92 )

作者： DAMAK, T BABARY, JP NIHTILA, MT

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Application of neural networks for system identification of an adsorption column

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Neural Computing & Applications 1993年第2期1卷 160-165页

作者： Bulsari, A.B. Palosaari, S. Chemical Engineering Lappeenranta University of Technology Lappeenranta SF 53851 Finland

This work illustrates the use of neural networks for system identification of the dynamics of a distributed parameter system, an adsorption column for waste-water treatment of water containing toxic chemicals. system identification of this process is done from simulated data for this work. The inputs to the networks include the state of the column at a given point in time and the system input, the velocity. The network predicts the change in the state over a period of time based on these inputs. Recurrent networks were found to be capable of simulating the whole operation of the column from an initial state of zero concentrations throughout the column, and thus predicting the complete breakthrough curves. The feasibility of system identification of this process has been established using synthetic noisy data, which indicates that the same can be performed from experimental data when all the required measurements are available. © 1993 Springer-Verlag London Limited.

关键词： Adsorption distributed parameter system system identification

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The Model Identification and Optimal Control of distributed parameter systems in Economic Management

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IFAC Proceedings Volumes 1992年第16期25卷 57-61页

作者： Pan Dehui Department of Management Engineering Northeast University of Technology Shenyang PRC

The paper studied the model identification method of the Green’s function for dsitributed parameter systems in economy, maeagement or engineering. It discussed the method of the establishment of the model with the no... 详细信息

关键词： distributed parameter system Green’s function model identification non-quantitative input quantification optimal control

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STABILIZATION OF A distributed system WITH A STABLE COMPENSATOR

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MATHEMATICS OF CONTROL SIGNALS AND systemS 1992年第1期5卷 1-22页

作者： STAFFANS, OJ 1. Institute of Mathematics Helsinki University of Technology SF-02150 Espoo 15 Finland

It is proved that a multivariable distributed system, that has no poles on the boundary of the half-plane of analyticity of its transfer function, can be stabilized with a stable strictly proper lumped compensator if and only if the standard parity interlacing condition is satisfied. The problem is formulated and solved in a Banach algebra of transfer functions that are Laplace transforms of measures having a finite total variation with respect to some given submultiplicative weight function. In particular, this result can be applied to transfer functions in the Callier-Desoer class, and it seems to be new even for this class. The proofs are closely related to and based on the scalar case solved previously.

关键词： distributed parameter system STRONG STABILIZATION STABLE COMPENSATOR PARITY INTERLACING CONDITION CALLIER-DESOER CLASS

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DERIVATION OF GREENS-FUNCTIONS OF COMPLEX STRUCTURES USING COMPUTER ALGEBRA

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AIAA JOURNAL 1992年第10期30卷 2540-2545页

作者： FABUNMI, JA CHANG, PC UNIV MARYLAND COLL PK MD 20742 USA

The manual implementation of existing formulations for the algebraic derivation of Green's functions of complex interconnected structures based on the Green's functions of the component structures can be very tedious. The objective of this investigation is to explore the application of computer algebra to this problem. For simple structures such as uniform Euler-Bernoulli beams and flat plates, the Green's functions can be derived directly from the partial differential equations. The more general forms of these functions are expressed as infinite series of terms contributed by the characteristic functions and parameters of the system. In this paper, computer algebra has been used to automate the derivation of the characteristic functions and parameters of the combined structure. Examples of complex structures such as uniform cantilivered Euler-Bernoulli beams to which discrete spring-mass substructures have been attached were used to assess the accuracy of the proposed method in comparison with results of finite element analyses and previous techniques for solving the same problem. The results show that computer algebra derives the correct functions and parameters to any specified accuracy. Moreover, problems of numerical ill conditioning associated with matrix methods are avoided.

关键词： Dirac Delta Function Euler Bernoulli Beams Finite Element Analysis Cantilever Beam Free Vibrations distributed parameter system Structural system Flexural Rigidity Space Structures Zero Gravity

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WIDE-BAND CONTROL OF GYRO ACCELEROMETER MULTISENSORS IN A STRAPDOWN GUIDANCE-system

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 1992年第4期15卷 855-860页

作者： CONSTANCIS, P SORINE, M INST NATL RECH INFORMAT & AUTOMAT F-78153 LE CHESNAYFRANCE UNIV PARIS 09 F-75016 PARISFRANCE

This paper describes an inertial measurement unit based on three dry tuned gyroscopes, two of which are unbalanced. This configuration, without the three usual accelerometers, leads to savings in space, weight, and cost that are necessary in guidance systems for agile missiles. Design objectives are wideband estimation of angular rate and linear acceleration applied to the inertial measurement unit together with high stiffness of caging loops. The contribution of this paper is to show how to address the coupled high-frequency dynamics of the six measurement outputs of the system, by applying the so-called linear quadratic Gaussian technique. First the linearized model of the rotor motion of each dry-tuned gyroscope is derived from a mechanical analysis. Then the design of the controller/estimator is described. Performances are illustrated with test data.

关键词： Accelerometer Guidance system Gyroscopes IMU Linear Quadratic Gaussian Agile Missiles distributed parameter system Gaussian White Noise Riccati Equations Damping Coefficient

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ACTUATOR PLACEMENT IN STRUCTURAL CONTROL

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 1992年第1期15卷 40-48页

作者： CHOE, K BARUH, H RUTGERS STATE UNIV DEPT MECH & AEROSP ENGNNEW BRUNSWICKNJ 08903

The placement of force and torque actuators for structural control problems is considered. Objective functions are defined based on the elements of the actuator influence matrix, and optimization studies are conducted. The performance of the control is compared. The results indicate that a relatively even distribution of the actuators gives satisfactory results, whereas a close spacing of the actuators leads to excessive fuel and energy use. In all cases, several evenly spaced actuator distributions are found to be suitable. In addition, torque actuators are found to be less desirable than force actuators because they excite the higher modes to a greater degree. The efficiency of piecewise-continuous actuators is analyzed. Piecewise-continuous actuators are more realistic models than point actuators and they reduce stress levels. However, if their contact area is too large, they use more fuel.

关键词： Actuators Energy Transfer Mathematical Models Fuel Consumption Vibration Suppression Modal Space Control distributed parameter system Dirac Delta Function Flexible Structures Optimal Control

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CONTROL OF FLEXIBLE SPACECRAFT WITH TIME-VARYING CONFIGURATION

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 1992年第2期15卷 314-324页

作者： MEIROVITCH, L KWAK, MK Virginia Polytechnic Institute and State University Blacksburg Virginia 24061

This paper is concerned with the dynamics and control of systems with time-varying configuration, such as maneuvering articulated flexible spacecraft. The mathematical model consists of a rigid platform and a given number of retargeting flexible antennas. The mission consists of maneuvering the antennas so as to coincide with preselected lines of sight while stabilizing the platform in an inertial space and suppressing the elastic vibration of the antennas. A perturbation technique permits the derivation of a new control law for systems with time-varying configuration, in which the time-varying terms are relatively small. According to the proposed perturbation method, the control gains consist of zero-order time-invariant gains obtained from the solution of a matrix algebraic Riccati equation, which are valid both during and after the maneuver, and higher-order time-varying gains obtained from the solution of matrix differential Lyapunov equations, which are valid only during the maneuver. The approach is illustrated by means of a numerical example.

关键词： Flexible Spacecrafts distributed parameter system Antennas Algebraic Riccati Equation Elastic Vibration Perturbation Method Control systems Mathematical Models Riccati Equations Numerical Integration

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