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-chemica...
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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.
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 ...
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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.
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 temper...
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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.
Modelling, simulation, state estimation and feedback control of a distributedparameter fixed-bed bioreactor are studied in reference to two different types of boundary conditions. The bioreactor is described by two n...
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Modelling, simulation, state estimation and feedback control of a distributedparameter 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.
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 ...
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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.
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 in...
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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.
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...
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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.)
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 semidefinit...
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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.
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...
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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 disturbances. This design follows the separation (CSA)
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 tech...
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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.
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