Abstract We consider a one-dimensional heat process with exponential internal heat source described by a second order, non-linear, parabolic partial differential equation. The model can describe various physical proce...
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Abstract We consider a one-dimensional heat process with exponential internal heat source described by a second order, non-linear, parabolic partial differential equation. The model can describe various physical processes from electric space charge problem, diffusion-reaction processes, some nuclear process or explosion. Due to the exponential heat source, stability is of prime interest. We investigate under which conditions (i.e. boundary conditions, parameters etc.) the process remains stable and provide the stability region for different boundary conditions. Another important question concerns what happens if the source gain exceeds the stability limit. Then, inevitably, a blow-up (explosion) happens, that is, given sufficient time, the temperature will grow unbounded. In this case it is important to estimate the time until blow-up. Based on reasonable assumptions we provide a good estimate for the blow-up time. Computer simulations verified the results.
Electrodeposition is a complex partially observed mass-transfer process driven by several surface reactions without exact model. In this article, the process uncertainties are described by a finite number of Wiener pr...
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Electrodeposition is a complex partially observed mass-transfer process driven by several surface reactions without exact model. In this article, the process uncertainties are described by a finite number of Wiener processes in a stochastic model applied in the filtering and control problems. These problems are solved as a boundary observation-control problem based on a finite diffusion model with uncertainties in the domain interior and on the boundaries. A mixed boundary problem is considered on an interval with the Dirichlet data on one end (bulk solution) and Neumann data on the other end (cathode surface). The concentration of oxidising species in the domain interior is unattainable for observations but the flux on the boundary (electric current) can be measured with a limited accuracy (sensor error). The total flux for the main and side reactions is controlled by the current density on the cathode surface. The disturbing effect of the side reactions is modelled as a noise. The concentration of species is stabilised at the desired level near to the cathode surface with a relatively simple feedback control. The concentration on the boundary and in the domain is estimated as a conditionally Gaussian process in the course of filtering. The estimated conditional mean of concentration is solved from a stochastic partial differential equation in dependence on the covariance kernel. A relatively good quality of estimation and control is demonstrated in the process of simulation in the realistic conditions for a copper deposition process.
Abstract Particulate processes like industrial crystallisation or granulation are often described by population balances. This leads to mathematical models containing partial integro differential equations. In many ca...
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Abstract Particulate processes like industrial crystallisation or granulation are often described by population balances. This leads to mathematical models containing partial integro differential equations. In many cases, the flow conditions of the fluid phase have a strong impact on the particle formation. To describe this properly, Navier Stokes equations have to be solved in addition. The resulting model equation system is too complicated to apply them to typical process control tasks. Reduced models are desirable. In this contribution, the use of proper orthogonal decomposition is suggested as a powerful reduction method. The usefulness of the approach is illustrated by two application examples: a granulation process with particle aggregation and a crystallisation process with particle growth and complex fluid dynamics.
In this paper we study output regulation of distributed parameter systems with infinite-dimensional exosystems. The purpose of the paper is to find simple and minimal conditions on the signal generator under which the...
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In this paper we study output regulation of distributed parameter systems with infinite-dimensional exosystems. The purpose of the paper is to find simple and minimal conditions on the signal generator under which the solvability of the output regulation problem can be characterized by the solvability of the regulator equations. We also study the properties of the dynamic steady state of the closed-loop system and the uniqueness of the solution of Sylvester operator equations. The presented results have applications in robust regulation of infinite-dimensional systems.
In this work, the boundary control of a distributedparameter system modelled by linear parabolic partial differential equations (PDEs) with spatially varying coefficients is studied. An infinite-dimensional state spa...
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In this work, the boundary control of a distributedparameter system modelled by linear parabolic partial differential equations (PDEs) with spatially varying coefficients is studied. An infinite-dimensional state space setting is considered and an exact transformation of the boundary actuation is realised to obtain an evolutionary model. The evolutionary model which incorporates the spatially varying coefficients of the underlying set of the PDEs is used for subsequent linear quadratic regulator synthesis. The formulated linear quadratic-state feedback controller is applied to a nonlinear model of the reactor and its performance is studied.
Particle processes with agglomeration or breakage are often described by population balances. This leads to mathematical models containing partial integro differential equations. It is quite challenging to solve such ...
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Particle processes with agglomeration or breakage are often described by population balances. This leads to mathematical models containing partial integro differential equations. It is quite challenging to solve such equations numerically and to apply them to process control tasks. Reduced models for agglomeration and breakage processes are desirable. In this contribution, the use of proper orthogonal decomposition is suggested as a method to derive such reduced models. The reduction method is applied to a batch granulator. A low order model is formulated and found to be in good agreement with the reference model. The usefulness of the low order model is demonstrated by applying it to an optimal control problem.
This work focuses on the evaluation of some of the advanced recursive state estimation techniques applied to packed bed reactors. Tubular, packed or fixed bed reactors are typically modeled as infinite dimensional par...
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This work focuses on the evaluation of some of the advanced recursive state estimation techniques applied to packed bed reactors. Tubular, packed or fixed bed reactors are typically modeled as infinite dimensional partial differential equations, also called distributed parameter systems (DPS). Discretization methods such as orthogonal collocation or any other polynomial approximation can be used to convert these DPS into a set of Ordinary Differential Equations (ODE) or Differential Algebraic Equations (DAE), that are more suitable for application of the estimation algorithms. Here we demonstrate the superior performance of the Ensemble Kalman Filter over its other variants (EKF and UKF) for a tubular reactor model. This work also includes the evaluation of the constrained forms of these algorithms for the same tubular reactor model and the results show that the Constrained EnKF which is a nondeterministic approach is able to estimate the states accurately and is less susceptible to numerical errors unlike the Constrained UKF and Constrained EKF which encounter the problem of the covariance matrix becoming negative definite.
Electrodeposition process filtering and boundary control problem is solved in this paper based on a stochastic model that depends on a finite number of Wiener processes. The problem is solved as a boundary observation...
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Electrodeposition process filtering and boundary control problem is solved in this paper based on a stochastic model that depends on a finite number of Wiener processes. The problem is solved as a boundary observation-control problem based on a finite diffusion model with uncertainties in the domain interior and on the boundaries. A mixed boundary problem is considered in an interval with the Dirichlet data on one end (bulk solution) and Neumann data on the other end (cathode surface). Since the concentration of oxidizing species is unattainable for observations the flux on the boundary is measured with a sensor noise. The total flux of the main reaction and side reactions is controlled by the electric current measurements on the cathode while the disturbing effect of the side reactions is considered as a noise. The concentration of species is stabilised at the desired level near to the cathode surface with a relatively simple feedback control. The concentration on the boundary and in the domain is estimated as a conditionally Gaussian process in the course of filtering. The estimated conditional mean of concentration is solved from a stochastic PDE in dependence on the covariance kernel. A relatively good quality of estimation and control is demonstrated in process of simulation in the realistic conditions for a copper deposition process.
Abstract Open-loop and closed-loop control problems for distributed parameter systems, described by parabolic partial differential equations, are considered in this contribution. The goal of the study is the developme...
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Abstract Open-loop and closed-loop control problems for distributed parameter systems, described by parabolic partial differential equations, are considered in this contribution. The goal of the study is the development of strategies for control and estimation of states, disturbances, and parameters. These strategies are based on the method of integrodifferential relations, a projection approach, and a suitable finite element technique. A real-time applicable control algorithm is proposed and its specific features are discussed. A verification of the control laws derived in this contribution is performed taking into account explicit error estimates resulting directly from the integrodifferential approach. The parameters, geometry, and actuation principles of a heat transfer system available at the Chair of Mechatronics, University of Rostock, are used for the numerical simulation and experimental validation. The test setup consists of a metallic rod equipped with a finite number of Peltier elements which are used as distributed control inputs allowing for active cooling and heating.
In this paper, a comprehensive approach for modelling, parameter estimation and global simulation of the grinding circuit of the Kolwezi Concentrator is presented. This process can be described by a nonlinear distribu...
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In this paper, a comprehensive approach for modelling, parameter estimation and global simulation of the grinding circuit of the Kolwezi Concentrator is presented. This process can be described by a nonlinear distributedparameter system. To differentiate between wet and dry grinding, the derived model takes into account the increase of the specific rate of breakage in the wet grinding process. In order to determine material transport dynamics within the mills, a new experimental method has been developed. Due to the lack of a colorant or a radioactive sensor, this procedure is based on the use of the G41 foaming as tracer. Both steady-state and dynamic simulation results are discussed and are shown to be in agreement with the experimental data.
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