Resumo Recentemente, uma classe de algoritmos contınuos foi analisada a partir da perspectiva da ... more Resumo Recentemente, uma classe de algoritmos contınuos foi analisada a partir da perspectiva da teoria de controle.[1] Esta abordagem também propicia o projeto de alguns algoritmos novos que precisam ser codificados e testados em ambientes de computaçao, utilizando problemas padrao da literatura. Neste trabalho apresenta-se uma implementaçao de um algoritmo contınuo para achar zeros de uma funçao polinomial. A implementaçao, feita no ambiente MATLAB, também permite a determinaçao de zeros de um polinômio ...
Proposes the control of predator-prey type models through the use of on-off control, also known a... more Proposes the control of predator-prey type models through the use of on-off control, also known as a threshold policy in the biological context. Both discontinuous control, similar to variable structure control, and a continuous version of this control are used. Robustness of the proposed controls is discussed.
Proceedings of the 48h IEEE Conference on Decision and Control (CDC) held jointly with 2009 28th Chinese Control Conference, 2009
This paper proposes extensions to a recent control Liapunov function (CLF) based method for desig... more This paper proposes extensions to a recent control Liapunov function (CLF) based method for designing dynamical systems with trajectories that converge to the zeros of a nonlinear vector function f. Specifically, the CLF design method is extended to the case when the Jacobian of the vector function can be decomposed into a known part and a partially known part, for which certain norm bounds are known. The extension of existing zero finding methods to this setting allows the consideration of functions which have singular Jacobians as well as the underdetermined case of a nonlinear system of equations in which there are more unknowns than equations. It is shown through simulation examples that methods that use dynamical systems that correspond to first order ordinary differential equations (ODEs) are less effective than those which use second order ODEs.
Proceedings of the 36th IEEE Conference on Decision and Control, 1997
Abstract The stability of asynchronous multirate linear systems is studied. The Ritchey-Franklin ... more Abstract The stability of asynchronous multirate linear systems is studied. The Ritchey-Franklin stability criterion that was derived under the assumption that certain state transition matrices are diagonalizable was preceeded by more general stability criteria for the so called desynchronized systems and difference inclusions in the Russian literature. These conditions are modified in this paper to formulate a general approach that does not require any diagonalizability assumptions and applied to an illustrative example in order to ...
Proceedings of the 41st IEEE Conference on Decision and Control, 2002., 2002
Abstract Proposes the control of predator-prey type models through the use of on-off control, als... more Abstract Proposes the control of predator-prey type models through the use of on-off control, also known as a threshold policy in the biological context. Both discontinuous control, similar to variable structure control, and a continuous version of this control are used. Robustness of the proposed controls is discussed.
Esta dissertação propõe um método de digitalização de filmes radiográficos que utiliza um scanner... more Esta dissertação propõe um método de digitalização de filmes radiográficos que utiliza um scanner de transparências convencional de baixo custo (scanner de mesa A4) e de um software de costura de imagens especialmente desenvolvido neste projeto. Este sistema faz aquisições parciais da imagem
Matrix Diagonal Stability in Systems and Computation, 2000
Abstract This chapter presents the matrix theory concepts of diagonal stability and also of D-sta... more Abstract This chapter presents the matrix theory concepts of diagonal stability and also of D-stability and gives the properties of these classes of matrices in various cases that are used extensively in the remaining chapters of this book as well as related results that are important in themselves. It is thus intended as a reference chapter for the whole book. The reader does not have to read this whole chapter before reading the rest of the book, but rather consult it when necessary. There is, of course, no claim to completeness, in terms of ...
Multi-user mobile communication systems use adaptive and linearly constrained adaptive filters fo... more Multi-user mobile communication systems use adaptive and linearly constrained adaptive filters for blind and non-blind adaptive interference cancelation, multipath reduction, equalization, and adaptive beamforming. A conjugate gradient and a steepest descent method for real-time processing are proposed and applied to blind adaptive array processor. Simulations show that the proposed algorithms have performance comparable to those of algorithms proposed earlier.
This article presents an unified way to design neural networks characterized as second order ordi... more This article presents an unified way to design neural networks characterized as second order ordinary differential equations (ODE), that aim to find the global minimum of nonconvex scalar functions. These neural networks, alternative referred to as continuous time algorithms, are interpreted as dynamical closed loop control systems. The design is based on the control Liapunov function (CLF) method. For nonconvex scalar functions, the goal of these algorithms is to produce trajectories, starting from an arbitrarily chosen initial guess, that do not get stuck in local minima, thereby increasing the chances of converging to the global minimum.
IEE Proceedings - Control Theory and Applications, 2001
A method is introduced for sliding-surface design for multivariable linear systems based on the p... more A method is introduced for sliding-surface design for multivariable linear systems based on the placement of the transfer function transmission zeros from the control signal to the (fictitious) output which specifies the sliding surface. The design procedure uses the Luenberger feedback canonical form with input normalisation, which in turn is calculated using numerically reliable orthogonal transformations from the SLICOT library.
The standard conjugate gradient (CG) method uses orthogonality of the residues to simplify the fo... more The standard conjugate gradient (CG) method uses orthogonality of the residues to simplify the formulas for the parameters necessary for convergence. In adaptive filtering, the sample-by-sample update of the correlation matrix and the cross-correlation vector causes a loss of the residue orthogonality in a modified online algorithm, which, in turn, results in loss of convergence and an increase of the filter quadratic mean error. This letter extends a recently proposed control Liapunov function analysis of the CG method viewed as a dynamic system in the standard feedback configuration to the case of adaptive filtering.
Abstract—It is shown how standard iterative methods for solving linear and nonlinear equations ca... more Abstract—It is shown how standard iterative methods for solving linear and nonlinear equations can be approached from the point of view of control. Appropriate choices of control Liapunov functions lead to both continuous and discrete-time versions of the well known Newton-Raphson and conjugate gradient algorithms as well as their common variants. Insights into these algorithms that result from the control approach are discussed.
Resumo—Métodos numéricos são implementados em computadores digitais utilizando a aritmética de pr... more Resumo—Métodos numéricos são implementados em computadores digitais utilizando a aritmética de precisão finita. Nesse caso os números reais/complexos são representados com palavras de tamanho finito. Essa representação resulta no truncamento/arredondamento dos números, o que acarreta erros nos algoritmos. Esses erros podem acarretar, por sua vez, uma perda de algumas das propriedades dos métodos numéricos (ortogonalidade dos resíduos do método do gradiente conjugado por exemplo), ...
Multi-user mobile communication systems use linearly constrained adaptive filters for a blind ada... more Multi-user mobile communication systems use linearly constrained adaptive filters for a blind adaptive interference cancelation and/or adaptive beamforming. Conjugate gradient (CG) techniques have been proposed, in the literature, for solving the adaptive filtering and the linearly constrained adaptive filtering problems. In adaptive filtering, the sample-by-sample update of the correlation matrix and the cross-correlation vector causes a loss of the residue orthogonality in a modified online algorithm, which, in turn, results in ...
1Center of Engineering, Modeling and Applied Social Sciences (CECS) Federal University of ABC E-m... more 1Center of Engineering, Modeling and Applied Social Sciences (CECS) Federal University of ABC E-mail: [email protected] 2Dept. of Electrical Engineering, COPPE/NACAD Federal University of Rio de Janeiro E-mail: [email protected] ... First International Congress “Ecological Engineering: From concepts to application” ... Meza, Bhaya (UFABC/UFRJ) Using a TPD and TPHD EECA'09 1 / 19 ... Control of discrete time logistic models Special requirements: ... ► Nonstandard discretization scheme (Mickens, 1994) (preserving qualitative properties). ...
Resumo—Os controladores Proporcional, Integral e Derivativo (PID) são amplamente utilizados em ap... more Resumo—Os controladores Proporcional, Integral e Derivativo (PID) são amplamente utilizados em aplicações de controle. A maioria das regras conhecidas de sintonia dos ganhos de controladores PID são ainda apenas para ganhos PID invariantes no tempo. Neste artigo uma técnica de projeto de controladores PID com ganhos variantes no tempo é proposto para uma classe de sistemas lineares. Esta técnica, baseada em uma escolha adequada de funções de controle de Liapunov, determina os parâmetros ótimos ...
Resumo Recentemente, uma classe de algoritmos contınuos foi analisada a partir da perspectiva da ... more Resumo Recentemente, uma classe de algoritmos contınuos foi analisada a partir da perspectiva da teoria de controle.[1] Esta abordagem também propicia o projeto de alguns algoritmos novos que precisam ser codificados e testados em ambientes de computaçao, utilizando problemas padrao da literatura. Neste trabalho apresenta-se uma implementaçao de um algoritmo contınuo para achar zeros de uma funçao polinomial. A implementaçao, feita no ambiente MATLAB, também permite a determinaçao de zeros de um polinômio ...
Proposes the control of predator-prey type models through the use of on-off control, also known a... more Proposes the control of predator-prey type models through the use of on-off control, also known as a threshold policy in the biological context. Both discontinuous control, similar to variable structure control, and a continuous version of this control are used. Robustness of the proposed controls is discussed.
Proceedings of the 48h IEEE Conference on Decision and Control (CDC) held jointly with 2009 28th Chinese Control Conference, 2009
This paper proposes extensions to a recent control Liapunov function (CLF) based method for desig... more This paper proposes extensions to a recent control Liapunov function (CLF) based method for designing dynamical systems with trajectories that converge to the zeros of a nonlinear vector function f. Specifically, the CLF design method is extended to the case when the Jacobian of the vector function can be decomposed into a known part and a partially known part, for which certain norm bounds are known. The extension of existing zero finding methods to this setting allows the consideration of functions which have singular Jacobians as well as the underdetermined case of a nonlinear system of equations in which there are more unknowns than equations. It is shown through simulation examples that methods that use dynamical systems that correspond to first order ordinary differential equations (ODEs) are less effective than those which use second order ODEs.
Proceedings of the 36th IEEE Conference on Decision and Control, 1997
Abstract The stability of asynchronous multirate linear systems is studied. The Ritchey-Franklin ... more Abstract The stability of asynchronous multirate linear systems is studied. The Ritchey-Franklin stability criterion that was derived under the assumption that certain state transition matrices are diagonalizable was preceeded by more general stability criteria for the so called desynchronized systems and difference inclusions in the Russian literature. These conditions are modified in this paper to formulate a general approach that does not require any diagonalizability assumptions and applied to an illustrative example in order to ...
Proceedings of the 41st IEEE Conference on Decision and Control, 2002., 2002
Abstract Proposes the control of predator-prey type models through the use of on-off control, als... more Abstract Proposes the control of predator-prey type models through the use of on-off control, also known as a threshold policy in the biological context. Both discontinuous control, similar to variable structure control, and a continuous version of this control are used. Robustness of the proposed controls is discussed.
Esta dissertação propõe um método de digitalização de filmes radiográficos que utiliza um scanner... more Esta dissertação propõe um método de digitalização de filmes radiográficos que utiliza um scanner de transparências convencional de baixo custo (scanner de mesa A4) e de um software de costura de imagens especialmente desenvolvido neste projeto. Este sistema faz aquisições parciais da imagem
Matrix Diagonal Stability in Systems and Computation, 2000
Abstract This chapter presents the matrix theory concepts of diagonal stability and also of D-sta... more Abstract This chapter presents the matrix theory concepts of diagonal stability and also of D-stability and gives the properties of these classes of matrices in various cases that are used extensively in the remaining chapters of this book as well as related results that are important in themselves. It is thus intended as a reference chapter for the whole book. The reader does not have to read this whole chapter before reading the rest of the book, but rather consult it when necessary. There is, of course, no claim to completeness, in terms of ...
Multi-user mobile communication systems use adaptive and linearly constrained adaptive filters fo... more Multi-user mobile communication systems use adaptive and linearly constrained adaptive filters for blind and non-blind adaptive interference cancelation, multipath reduction, equalization, and adaptive beamforming. A conjugate gradient and a steepest descent method for real-time processing are proposed and applied to blind adaptive array processor. Simulations show that the proposed algorithms have performance comparable to those of algorithms proposed earlier.
This article presents an unified way to design neural networks characterized as second order ordi... more This article presents an unified way to design neural networks characterized as second order ordinary differential equations (ODE), that aim to find the global minimum of nonconvex scalar functions. These neural networks, alternative referred to as continuous time algorithms, are interpreted as dynamical closed loop control systems. The design is based on the control Liapunov function (CLF) method. For nonconvex scalar functions, the goal of these algorithms is to produce trajectories, starting from an arbitrarily chosen initial guess, that do not get stuck in local minima, thereby increasing the chances of converging to the global minimum.
IEE Proceedings - Control Theory and Applications, 2001
A method is introduced for sliding-surface design for multivariable linear systems based on the p... more A method is introduced for sliding-surface design for multivariable linear systems based on the placement of the transfer function transmission zeros from the control signal to the (fictitious) output which specifies the sliding surface. The design procedure uses the Luenberger feedback canonical form with input normalisation, which in turn is calculated using numerically reliable orthogonal transformations from the SLICOT library.
The standard conjugate gradient (CG) method uses orthogonality of the residues to simplify the fo... more The standard conjugate gradient (CG) method uses orthogonality of the residues to simplify the formulas for the parameters necessary for convergence. In adaptive filtering, the sample-by-sample update of the correlation matrix and the cross-correlation vector causes a loss of the residue orthogonality in a modified online algorithm, which, in turn, results in loss of convergence and an increase of the filter quadratic mean error. This letter extends a recently proposed control Liapunov function analysis of the CG method viewed as a dynamic system in the standard feedback configuration to the case of adaptive filtering.
Abstract—It is shown how standard iterative methods for solving linear and nonlinear equations ca... more Abstract—It is shown how standard iterative methods for solving linear and nonlinear equations can be approached from the point of view of control. Appropriate choices of control Liapunov functions lead to both continuous and discrete-time versions of the well known Newton-Raphson and conjugate gradient algorithms as well as their common variants. Insights into these algorithms that result from the control approach are discussed.
Resumo—Métodos numéricos são implementados em computadores digitais utilizando a aritmética de pr... more Resumo—Métodos numéricos são implementados em computadores digitais utilizando a aritmética de precisão finita. Nesse caso os números reais/complexos são representados com palavras de tamanho finito. Essa representação resulta no truncamento/arredondamento dos números, o que acarreta erros nos algoritmos. Esses erros podem acarretar, por sua vez, uma perda de algumas das propriedades dos métodos numéricos (ortogonalidade dos resíduos do método do gradiente conjugado por exemplo), ...
Multi-user mobile communication systems use linearly constrained adaptive filters for a blind ada... more Multi-user mobile communication systems use linearly constrained adaptive filters for a blind adaptive interference cancelation and/or adaptive beamforming. Conjugate gradient (CG) techniques have been proposed, in the literature, for solving the adaptive filtering and the linearly constrained adaptive filtering problems. In adaptive filtering, the sample-by-sample update of the correlation matrix and the cross-correlation vector causes a loss of the residue orthogonality in a modified online algorithm, which, in turn, results in ...
1Center of Engineering, Modeling and Applied Social Sciences (CECS) Federal University of ABC E-m... more 1Center of Engineering, Modeling and Applied Social Sciences (CECS) Federal University of ABC E-mail: [email protected] 2Dept. of Electrical Engineering, COPPE/NACAD Federal University of Rio de Janeiro E-mail: [email protected] ... First International Congress “Ecological Engineering: From concepts to application” ... Meza, Bhaya (UFABC/UFRJ) Using a TPD and TPHD EECA'09 1 / 19 ... Control of discrete time logistic models Special requirements: ... ► Nonstandard discretization scheme (Mickens, 1994) (preserving qualitative properties). ...
Resumo—Os controladores Proporcional, Integral e Derivativo (PID) são amplamente utilizados em ap... more Resumo—Os controladores Proporcional, Integral e Derivativo (PID) são amplamente utilizados em aplicações de controle. A maioria das regras conhecidas de sintonia dos ganhos de controladores PID são ainda apenas para ganhos PID invariantes no tempo. Neste artigo uma técnica de projeto de controladores PID com ganhos variantes no tempo é proposto para uma classe de sistemas lineares. Esta técnica, baseada em uma escolha adequada de funções de controle de Liapunov, determina os parâmetros ótimos ...
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