Invariant Theory
Mostrando 13-24 de 82 artigos, teses e dissertações.
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13. Filtragem robusta de sistemas lineares invariantes no tempo por meio de funções de Lyapunov polinomiais / Robust filtering of linear time invariant systems by means of polynomial Lyapunov functions
This work presents new convex optimization procedures for full order robust H2 and H? filter design for continuous and discrete-time uncertain linear systems. The time-invariant uncertain parameters are supposed to belong to a polytope with known vertices. Thanks to the use of a larger number of slack variables and homogeneous polynomial relaxations, linear
Publicado em: 2010
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14. Matrizes de conexão para as dinamicas continua e discreta / Connectiion matrices for the continuous and discrete dynamics
The goal of this work is to present the connection matrix by establishing a parallel between the continuous and discrete settings. The homological Conley index, the main element in the definition of the connection matrix, has a diferent form for flows or continuous maps. This index is a graded vector space in the continuous case whereas in the discrete case
Publicado em: 2010
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15. Algebraic methods for the computation of general reversible-equivariant mappings / Métodos algébricos para a obtenção de formas gerais reversíveis-equivariantes
In the global and local analysis of dynamical systems, we assume, in general, that the equations are in a normal form. In presence of symmetries, the equations and the problem domain are invariant under the group formed by these symmetries; in that case, the vector field is equivariant by the action of this group. When, in addition to the symmetries, we have
Publicado em: 2009
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16. Estimation of parameters of signals generated by time invariant linear systems / Estimação de parâmetros de sinais gerados por sistemas lineares invariantes no tempo
A study on the recovery of signals modeled by weighted sums of complex exponentials complex is presented. For this, basic concepts of signals and systems theory are introduced. In particular, the linear time invariant systems (LTI Systems) are considered, which can be mathematically represented by differential equations or difference equations, respectively,
Publicado em: 2009
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17. Recursive robust regulator for discrete-time state-space systems / Regulador robusto recursivo para sistemas lineares de tempo discreto no espaço de estado
This dissertation deals with robust recursive regulators for discrete-time systems subject to parametric uncertainties. A new quadratic functional based on the combination of penalty functions and game theory is proposed to solve this class of problems. An important issue of this approach is that the recursiveness can be performed without the need of adjusti
Publicado em: 2009
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18. Realimentação de saida robusta a partir de controladores dependentes de parametros para sistemas lineares incertos discretos no tempo / Robust output feedback starting from parameter-dependent controllers for discrete-time uncertain linear systems
Esta dissertação trata de um dos mais importantes problemas em aberto na teoria de controle, o projeto de controladores por realimentação estática de saída. A principal contribuição é propor um método para computar controladores robustos estáticos por realimentação de saída para sistemas lineares incertos discretos no tempo, usando um controlad
Publicado em: 2009
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19. Control and filtering of time-varying linear systems via parameter dependent Lyapunov functions / Controle e filtragem de sistemas lineares variantes no tempo por meio de funções de Lyapunov dependentes de parametros
The main contribution of this dissertation is to propose conditions for linear filter and controller design, considering both robust and parameter dependent structures, for discrete time-varying systems. The controllers, or filters, are obtained through the solution of optimization problems, formulated in terms of bilinear matrix inequalities, using a method
Publicado em: 2009
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20. MODOS QUASE-NORMAIS E A CORRESPONDÊNCIA ADS/CFT / QUASINORMAL MODES AND THE ADS/CFT CORRESPONDENCE
The electromagnetic and gravitational quasinormal mode spectra of plane-symmetric anti-de Sitter black holes are investigated in the present work. According to the AdS/CFT correspondence, the black hole quasinormal frequencies correspond to the poles of R-current and stress-energy tensor correlation functions in the holographically dual field theory: the N =
Publicado em: 2008
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21. The Conley index for discontinuous vector fields / O indice de Conley para campos de vetores descontinuos
The Conley index is a used as a topological invariant in the analysis of the qualitative behavior of dynamical systems. lnitially the theory was developed for continuous flows in finite dimensional spaces and later extended to the infinite dimensional setting as well as to the discrete case. ln this work, we present a Conley index theory for a class of disco
Publicado em: 2008
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22. Um grupo de Richard Thompson e seu invariante homotopico sigma / A Richard Thompson group and its homotopical sigma invariant
Neste projeto de mestrado, estudamos um dos grupos de Richard Thompson e apresentamos os cálculos de seu invariante homotópico Sigma, em qualquer dimensão m, onde m é um inteiro positivo. O grupo de Richard Thompson, denotado por F, foi por ele definido em 1965 e ficou conhecido, mais tarde, por suas propriedades homotópicas e homológicas interessantes
Publicado em: 2008
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23. Construção dos conceitos geométricos num contexto de formação inicial de professores dos anos iniciais do ensino fundamental
Several scientific papers denounce the abandonment of the teaching of geometry in the elementary school and one of the reasons given is the unpreparedness of the teacher. This paper analyzes, in the context of initial training, the acquisition of skills in geometry, through the analysis of the participation and written production of students from the course
Publicado em: 2008
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24. A Model-driven Approach to Formal Refactoring
Refactoring object-oriented software, as any other evolutionary tasks usually affects source code and object models, burdening developers to keep those artifacts correct and up to date Due to the gap between modeling and programming artifacts, refactoring efforts soon become duplicate and considerably expensive. In this context, currently used tool support,
Publicado em: 2008