A three-dimensional fuzzy logic controller (3-D FLC) is presented for the control of distributed parameter system (DPS). Different to the traditional FLC, the 3-D FLC deals with three-dimensional fuzzy set (3-D fuzzy ...
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(纸本)1424403316
A three-dimensional fuzzy logic controller (3-D FLC) is presented for the control of distributed parameter system (DPS). Different to the traditional FLC, the 3-D FLC deals with three-dimensional fuzzy set (3-D fuzzy set), i.e. the traditional fuzzy set plus spatial dimension. The proposed FLC still consists of defuzzification, rule inference, and defuzzilication. Different to the traditional FLC, the 3-D FLC can fuse information measured from space domain into a spatial membership function, and then rules will not increase as sensors increase for spatial measurement. Therefore, the 3-D FLC has the capability to handle spatial information. Application of the 3-D FLC is presented for a catalytic packed-bed reactor to show the effectiveness of the new fuzzy controller design, and comparisons with the traditional fuzzy controller are also given.
Process equipment that exhibits significant spatial variation of system properties, such as temperature or concentration in a fixed bed reactor, are typically modeled as distributed parameter systems. While some prope...
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Process equipment that exhibits significant spatial variation of system properties, such as temperature or concentration in a fixed bed reactor, are typically modeled as distributed parameter systems. While some properties of the final product exiting the equipment may depend oil the states concerning the endpoint, others may be a function of the history of processing within the equipment. In such instances, control of the spatial property profile may be beneficial. In this work, we explore the idea of profile control using extended MPC and outline the additional challenges that must be addressed in this context. In case that the target profile is unachievable, we present an MPC formulation that uses lexicographic optimization to prioritize the different sections of the profile. Simulation of a simple representative system namely a hypothetical plug flow reactor is used to demonstrate that the lexicographic optimization based M PC provides a systematic approach to profile control and spans between the endpoint control strategy and the whole profile control strategy. The benefits of lexicographic optimization based MPC were also demonstrated oil a large-scale distributed parameter system of industrial size, namely the continuous pulp digester. (C) 2008 Elsevier Ltd. All rights reserved.
Perspectives of application of mathematical models using concepts of fractional derivatives and integrals in ship dynamics are analyzed under the assumption that these must approximate the well-known and generally ack...
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Abstract A sensor location problem for monitoring network with stationary nodes used for estimating unknown parameters of distributed-parametersystem is addressed. In particular, the situation is considered, when the...
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Abstract A sensor location problem for monitoring network with stationary nodes used for estimating unknown parameters of distributed-parametersystem is addressed. In particular, the situation is considered, when the actual spatial positions of sensor nodes at the experimentation stage may be uncertain to some extent and randomly fluctuate around some locations specified at the configuration stage. In the presented approach, some results from experimental design theory for dynamic systems with random regressors are extended for the purpose of configuring a sensor network. Then, a simple algorithm based on the notion of approximate near minimum from statistical learning theory is adapted to select the most informative sensor locations. The delineated approach is illustrated by numerical example on a sensor network design for a two-dimensional convective diffusion process.
Modeling of distributed parameter systems (DPSs) is very difficult because of their infinite-dimensional, spatio-temporal nature and nonlinearities. A low-order, simple nonlinear and parsimonious model is often requir...
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Modeling of distributed parameter systems (DPSs) is very difficult because of their infinite-dimensional, spatio-temporal nature and nonlinearities. A low-order, simple nonlinear and parsimonious model is often required in real applications. In this study, a time/space separation-based Hammerstein modeling approach is proposed for unknown nonlinear DPS. Firstly, the Karhunen-Loeve (KL) method is used for the time/space separation, where the spatio-temporal output is decomposed into a few dominant spatial basis functions with temporal coefficients. Secondly, a low-order parsimonious Hammerstein model is identified from the low-dimensional data to reconstruct the system dynamics, where the parsimonious model structure is determined by the orthogonal forward regression and the parameters are estimated using the least squares estimation and the singular value decomposition. The algorithm does not require nonlinear optimization and it is numerically robust. This modeling is very suitable for control design. The simulations are presented to show the effectiveness of the proposed modeling method. (C) 2009 Elsevier Ltd. All rights reserved.
The stabilization of a one-dimensional wave equation with non-collocated observation at its unstable free end and control at another end is considered. The controller comprises a state estimator which is designed in t...
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The stabilization of a one-dimensional wave equation with non-collocated observation at its unstable free end and control at another end is considered. The controller comprises a state estimator which is designed in the case where the velocity is not available. The method of "backstepping" is adopted in our design of the feedback law. We use the theory of Co-semigroups and Lyapunov functionals to prove the strong stability of the resulting closed-loop system. (C) 2008 Elsevier Ltd. All rights reserved.
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.
Modeling of distributedparameter processes is a challenging problem because of their complex spatio-temporal nature, nonlinearities and uncertainties. In this study, a spatio-temporal Hammerstein modeling approach is...
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Modeling of distributedparameter processes is a challenging problem because of their complex spatio-temporal nature, nonlinearities and uncertainties. In this study, a spatio-temporal Hammerstein modeling approach is proposed for nonlinear distributedparameter processes. Firstly, the static nonlinear and the distributed dynamical linear parts of the Hammerstein model are expanded onto a set of spatial and temporal basis functions. In order to reduce the parametric complexity, the Karhunen-Loeve decomposition is used to find the dominant spatial bases with Laguerre polynomials selected as the temporal bases. Then, using the Galerkin method, the spatio-temporal modeling will be reduced to a traditional temporal modeling problem. Finally, the unknown parameters can be easily estimated using the least squares estimation and the singular value decomposition. In the presence of unmodeled dynamics, a multi-channel modeling framework is proposed to further improve the modeling performance. The convergence of the modeling can be guaranteed under certain conditions. The simulations are presented to show the effectiveness of this modeling method and its potential to a wide range of distributed processes. (C) 2008 Elsevier Ltd. All rights reserved.
In this article, the via fill ratio is stabilised at a desired level using optimal control values of plating time and current density for the plating process galvanostat. Both control variables are evaluated as functi...
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In this article, the via fill ratio is stabilised at a desired level using optimal control values of plating time and current density for the plating process galvanostat. Both control variables are evaluated as functions of the process state, and operating conditions follow typical preferences for the via fill technology applied in manufacturing of multilayered printed circuit boards. The optimal controls are obtained as a system of two equations solved numerically with the gradient descent method. Results of the numerical analysis are presented and discussed.
Many chemical processes are nonlinear distributed parameter systems with unknown uncertainties. For this class of infinite-dimensional systems, the low-order model identification from process data is very important in...
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Many chemical processes are nonlinear distributed parameter systems with unknown uncertainties. For this class of infinite-dimensional systems, the low-order model identification from process data is very important in practice. The dimension reduction with a principal component analysis (PCA) is only a linear approximation for nonlinear problem. In this study, a nonlinear dimension reduction based low-order neural model identification approach is proposed for nonlinear distributedparameter processes. First, a nonlinear principal component analysis (NL-PCA) network is designed for the nonlinear dimension reduction, which can transform the high-dimensional spatio-temporal data into a low-dimensional time domain. Then, a neural system can be easily identified to model this low-dimensional temporal data. Finally, the spatio-temporal dynamics can be reproduced using the nonlinear time/space reconstruction. The simulations on a typical nonlinear transport-reaction process show that the proposed approach can achieve a better performance than the linear PCA based modeling approach. (C) 2009 Elsevier Ltd. All rights reserved.
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