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Improvement of a chemical heat pump by computer-aided design

INTERNATIONAL JOURNAL OF ENERGY RESEARCH 1999年第12期23卷 1051-1082页

作者： Forges, P Forestier, A Amouroux, M Univ Perpignan CNRS IMP Grp Automat F-66860 Perpignan France

This paper deals with an optimization problem about thermal exchanges between a reactive porous environment and two networks of heat pipes together enclosed in a chemical heat pump reactor. Because all physico-chemical features of the reactive matter are fixed (actually the reactor contains a patented chemical mixture), the only way to optimise the quality of these exchanges, is to find an optimal location within the reactor for the heat pipes using ozone friendly fluid as the working fluid. Two numerical approaches, the first quantitative by the finite element method and the second based on the heat conduction hyperbolic theory, enabled us to obtain the same optimization results. Copyright (C) 1999 John Wiley & Sons, Ltd.

关键词： reactor of a chemical heat pump networks of heat pipes distributed parameter system energetical optimizing criterion moving boundaries optimal location finite element method thermal waves concept

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Two state estimators for the barium sulfate precipitation in a semi-batch reactor

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CHEMICAL ENGINEERING SCIENCE 2009年第4期64卷 646-660页

作者： Mangold, M. Bueck, A. Schenkendorf, R. Steyer, C. Voigt, A. Sundmacher, K. Max Planck Inst Dynam Komplexer Tech Syst D-39106 Magdeburg Germany Otto VonGuericke Univ Magdegurg Lehrstuhl Systemverfahrenstech D-39106 Magdeburg Germany

The on-line determination of particle property distributions by direct measurements is often difficult, because the measurement equations are not invertible or because the inverse problem is ill-posed. If the process is observable, one can use state estimation techniques in order to reconstruct unmeasurable internal states of the process. This is discussed here for a semi-batch precipitation reactor. A square root unscented Kalman filter and state estimation by online minimisation are studied for the case of a measurable average particle size. Both estimators use a one-dimensional population balance model. The two approaches are compared in simulations. (C) 2008 Elsevier Ltd. All rights reserved.

关键词： Precipitation Population balance State estimation Observer distributed parameter system Unscented Kalman filter Observation by online minimisation

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Control and modeling of temperature distribution in a tubular polymerization process

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COMPUTERS & CHEMICAL ENGINEERING 2007年第11期31卷 1516-1524页

作者： Cao, Liulin Li, Dazi Zhang, Chunyu Wu, Haiyan Beijing Univ Chem Technol Dept Automat Beijing 100029 Peoples R China

Temperature distribution along tubular reactors reveals the process of a polymerization reaction, so that it can be used as an indicator to monitor polymer molecular weight distribution. In this study, model of temperature distribution in a tubular polymerization reaction was developed using a B-spline neural network in conjunction with a linear recurrent neural network for the control purpose. This provides a new method for modeling distributed parameter system. Both dynamic and static neural network were applied to resolve the modeling of distribution function from a high dimensional data set. The dynamic neural network describes the time relationship of distribution function and the manipulated variables, whereas the static neural network describes the algebraic relationship of temperature distribution and position in tubular reactor. Using the error set of the expected and the measured temperature distribution as control indexes, optimal control sequence based on the distribution model can be derived. An adaptive control strategy was investigated under conditions with un-measurable noises and disturbances. An extended integral square error (EISE) control index was proposed, which introduces the real-time model error into the control strategy. This provides a feedback channel for the control, and therefore largely enhances the robustness and anti-disturbance performance of the control method. Simulation results demonstrate the effectiveness of the proposed method. (c) 2007 Elsevier Ltd. All rights reserved.

关键词： polymerization tubular reactor distributed parameter system B-spline neural network optimal control

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New boundary conditions and adaptive control of fixed-bed bioreactors

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CHEMICAL ENGINEERING AND PROCESSING-PROCESS INTENSIFICATION 1999年第1期38卷 35-44页

作者： Babary, JP Julien, S Nihtilä, MT Czeczot, J Metzger, M CNRS Lab Anal & Architecture Syst F-31077 Toulouse 4 France Univ Helsinki Dept Food Technol FIN-00014 Helsinki Finland Silesian Tech Univ Inst Automat Control PL-44100 Gliwice Poland

Modelling, simulation, state estimation and feedback control of a distributed parameter fixed-bed bioreactor are studied in reference to two different types of boundary conditions. The bioreactor is described by two nonlinear and coupled partial differential equations including a single space variable. Classical Danckwerts boundary conditions and so-called Salmi and Romanainen boundary conditions are the two alternatives applied. For process model simulation the method of orthogonal collocation is used in the spatial discretisation. The idea of linearising state-feedback control is applied in the controller design. For control law calculation, two estimation procedures are used: one for estimating the state variables and the specific growth rate, and the other for obtaining the substrate consumption rate of the micro-organisms in the reactor. The state estimator is based on asymptotic observer design. Estimation of the substrate consumption rate is based on temporal discretisation and on the recursive exponentially weighted least-squares procedure resulting in adaptive nature of the final control law. (C) 1999 Elsevier Science S.A. All rights reserved.

关键词： distributed parameter system boundary conditions estimation adaptive control wastewater treatment

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Top Tension Control of a Flexible Marine Riser by Using Integral-Barrier Lyapunov Function

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IEEE-ASME TRANSACTIONS ON MECHATRONICS 2015年第2期20卷 497-505页

作者： He, Wei Sun, Chen Ge, Shuzhi Sam Univ Elect Sci & Technol China Sch Automat Engn Chengdu 611731 Peoples R China Univ Elect Sci & Technol China Sch Automat Engn Chengdu 611731 Peoples R China Univ Elect Sci & Technol China Inst Robot Chengdu 611731 Peoples R China Univ Toronto Edward S Rogers Sr Dept Elect & Comp Engn Toronto ON M5S 3G4 Canada Natl Univ Singapore Dept Elect & Comp Engn Singapore 117576 Singapore Univ Elect Sci & Technol China Sch Comp Sci & Engn Inst Robot Chengdu 611813 Peoples R China

This paper presents a boundary controller for a flexible marine riser to suppress the riser's vibration with a top tension constraint. The flexible marine riser is described by a distributed parameter system with a partial differential equation and four ordinary differential equations. The boundary controller is designed at the top boundary of the riser based on an integral-barrier Lyapunov function to suppress the riser's tension at top. Adaptive control is designed when the system parametric uncertainty exists. With the proposed robust adaptive boundary control, uniformed boundedness under the ocean disturbance can be achieved. Stability analysis of the closed-loop system is given using the Lyapunov stability theory. Simulation results illustrate the effectiveness of the proposed boundary controller with top tension constraint.

关键词： Boundary control distributed parameter system flexible riser flexible structures vibration control

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SAMPLED DATA CONTROL OF FLEXIBLE STRUCTURES USING CONSTANT GAIN VELOCITY FEEDBACK

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 1984年第6期7卷 747-750页

作者： MCCLAMROCH, NH The University of Michigan Ann Arbor Michigan

A sampled data-controlled flexbile structure can be defined as a distributed parameter system, in which the structure input is the output of an ideal zero order hold and the structure output is sampled. The present investigation is concerned with the finite dimensional model M x(two dots) + K x = B u (1) y = C x(dot) (2). The relations include the structural displacement vector x, the force input vector u, and the velocity output vector y. The mass matrix M and the structural stiffness matrix K are assumed symmetric and positive definite. The input influence matrix B and the output influence matrix C are assumed to be dimensionless. Attention is given to several results which can serve as guidelines for choice of feedback gains and sampling time to guarantee that a sampled data-controlled structure is stable.

关键词： Flexible Structures distributed parameter system Feedback Control Influence Coefficients Optimal Control Modal Space Control Green's Function Structural Displacement Aerospace Engineering Sampled Data systems

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MODELING ERROR-BOUNDS FOR FLEXIBLE STRUCTURES WITH APPLICATION TO ROBUST-CONTROL

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 1991年第3期14卷 665-667页

作者： CHAIT, Y University of Massachusetts Amherst Massachusetts 01003

General formulas for computing useful error bounds for the approximations of large space structures are presented. The approximation error bounds are developed for systems whose dynamics can be represented by a series solution where each term in the series arises from a second-order ordinary differential equation. Uniform, frequency-dependent, and overall bounds are considered, and numerical computation aspects as well as a graphical interpretation are discussed. It is observed that the bounds developed in the study can be used to specify the order of the initial (open-loop) approximate model and the minimum number of modes necessary for (closed- loop) control synthesis. (V.T.)

关键词： distributed parameter system Flexible Structures Damping Ratio Large Space Structures Bernoulli Euler Beams Frequency Response Functions Computing

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INVARIANT SET ANALYSIS OF THE HUB-APPENDAGE PROBLEM

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 1993年第6期16卷 1191-1193页

作者： MUKHERJEE, R JUNKINS, JL TEXAS A&M UNIV SYST DEPT AEROSP ENGN COLL STN TX 77843 USA

The rest-to-rest maneuver of the distributed parameter system consisting of a rigid hub with four cantilevered flexible appendages was studied. The best choice of the control input resulted in the negative semidefiniteness of the derivative of the Lyapunov function. A invariant set analysis of the system was subsequently carried out using an asymptotic stability theorem. The analysis establishes the fact that the hub-appendage system is globally asymptotically stable when the system undergoes antisymmetric motion with deformation in unison.

关键词： distributed parameter system Autonomous systems Reaction Wheels

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Stability and convergence of a hybrid adaptive feedforward observer

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2003年第1期26卷 189-192页

作者： Tran, CM Southward, SC N Carolina State Univ Dept Mech & Aerosp Engn Educ Labs Raleigh NC 27695 USA Lord Corp Thomas Lord Res Ctr Cary NC 27511 USA

This paper investigates the stability and convergence of a hybrid observer, which contains a conventional closed-loop observer as well as an adaptive feedforward component, for systems subjected to nonstationary tonal... 详细信息

关键词： distributed parameter system Acoustic Ducts Supersonic Aircraft Resonance Frequencies Aerospace Engineering Mathematical Models Vibration Control Feedback Control Space Structures Optimal Control

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CONTROL OF distributed STRUCTURES WITH SMALL NONPROPORTIONAL DAMPING

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 1989年第6期12卷 930-932页

作者： MEIROVITCH, L NORRIS, MA Virginia Polytechnic Institute and State University Blacksburg

This paper examines the circumstances under which controls based on a self-adjoint structure yield satisfactory performance when applied to a closely related nonself-adjoint structure. To this end, a perturbation technique is used to compute the sensitivity of the closed-loop poles to small viscous damping. A numerical example is presented in which the control system performance is examined for varying amounts of nonproportional damping. The example indicates how large the nonproportional damping can be without degrading control system performance.

关键词： distributed parameter system Damping Coefficient Control system Design Modal Space Control Strain Rate Simply Supported Beams Structural Damping

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