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New control methods are developed for the unconstrained motion and constrained force and motion control of flexible robots. The dynamic equations of the flexible robots are partitioned as pseudostatic equilibrium equations and deviations from them. The pseudostatic equilibrium considered here is defined as a hypothetical state where the tip point variables have their desired values while the modal variables are instantaneously constant. Then, the control torques for the pseudostatic equilibrium and for the stabilization of the deviation equations are formed in terms of tip point coordinates, modal variables and contact force components. The performances of the proposed methods are illustrated on a planar two-link robot and on a spatial three-link robot. Unmodeled dynamics and measurement noises are also taken into consideration. Performance of the proposed motion control method is compared with the computed torque method.

Dans cette thèse, nous affinons l'étude des fonctions presque automorphes sur time scales introduites dans la littérature par Lizama et Mesquita, nous explorons de nouvelles propriétés de ces fonctions et appliquons les résultats à étudier l'existence et l'unicité de solution presque automorphe d'une nouvelle classe d'équations dynamiques sur time scales. Puis nous introduisons la notion de fonction presque automorphe de classe Cn, nous investiguons les propriétés fondamentales de ces fonctions et utilisons les résultats pour établir l'existence, l'unicité et la stabilité globale et exponentielle de solution presque automorphe de classe C1 d'un système d'équations dynamiques avec délai variable fini modélisant un réseau de neurones. Ensuite nous présentons le concept de fonctions asymptotiquement presque automorphes de classe Cn. Nous démontrons quasiment toutes les propriétés de ces fonctions, lesquelles nous permettent, sous des hypothèses convenables, d'établir, d'une part, que l'unique solution d'un problème avec condition initiale est asymptotiquement presque automorphe de classe C1, et d'autre part, l'existence et l'unicité de solution asymptotiquement presque automorphe pour une équation intégro-dynamque avec conditon initiale non locale sur time scales. Enfin, en utilisant la notion de semi-groupe sur time scales de Hamza et Oraby, nous généralisons les résultats de Lizama et Mesquita en dimension infinie, c'est-à-dire, nous étudions l'existence et l'unicité des solutions presque automorphes pour des équations dynamiques semi linéaires abstraites sur time scales. / In this thesis, we refine the notion of almost automorphic functions on time scales introduced in the literature by Lizama and Mesquita, we explore some new properties of such functions and apply the results to study the existence and uniqueness of almost automorphic solution for a new class of dynamic equations on time scales. Then we introduce the concept of almost automorphic functions of order n on time scales, we investigate the fundamental properties of these functions and we use the findings to establish the existence and uniqueness and the global stability of almost automorphic solution of one to a first order dynamical equation with finite time varying delay. Then we present the concept of asymptotically almost automorphic functions of order n on time scales. We study the properties of these functions and we use the results to prove, under suitable hypothesis, that the unique solution to a problem with initial condition is asymptotically almost automorphic of order one at the one hand, and the existence and uniqueness of asymptotically almost automorphic solution for an integro-dynamic equation with nonlocal initial conditon on time scales in other hand. Finally, using the concept of semigroup on time scales introduced by Hamza and Oraby, we generalize the results in Lizama and Mesquita's paper for abstract Banach spaces, that is, we study the existence and uniqueness of almost automorphic solution for semilinear abstract dynamic equations on time scales.

O objetivo desse trabalho é desenvolver métodos numéricos para simular escoamentos de cristais líquidos nemáticos governados pelas equações dinâmicas de Ericksen-Leslie. São apresentados dois métodos numéricos para a simulação de escoamentos de cristais líquidos nemáticos. O primeiro método foi desenvolvido para simular escoamentos tridimensionais de cristais líquidos nemáticos sob efeito de forte campo magnético enquanto que o segundo método foi desenvolvido para a simulação de escoamentos bidimensionais. Utilizando a notação de Einstein, as equações dinâmicas de Ericksen-Leslie são apresentadas. Empregando variáveis primitivas e coordenadas cartesianas, as equações governantes para escoamentos de cristais líquidos nemáticos são derivadas e as formulações matemáticas para a obtenção dos métodos numéricos são apresentadas. As equações descrevendo os métodos numéricos são resolvidas por um método numérico baseado na metodologia GENSMAC3D para o caso tridimensional enquanto que o método bidimensional é baseado na metodologia GENSMAC (GENeralized-Simplified-Marker-And-Cell). Em ambos os métodos, a técnica de diferenças finitas em uma malha deslocada é utilizada. As equações que descrevem as técnicas numéricas desenvolvidas foram incorporadas aos ambientes de simulação Freeflow2D e Freeflow3D. As condições de contorno para cada tipo de contorno são descritas em detalhes. A solução analítica apresentada por Stewart para o escoamento entre duas placas paralelas é utilizada para a validação do método numérico tridimensional. Empregando as hipóteses de escoamento desenvolvido e que o ângulo de orientação do diretor é pequeno, uma solução analítica para o escoamento em um canal bidimensional é encontrada. O método numérico bidimensional é então validado utilizando a solução analítica obtida. Utilizando refinamento de malha, resultados de convergência dos métodos numéricos são apresentados. Os métodos numéricos desenvolvidos nesse trabalho são aplicados para a simulação dos seguintes problemas: escoamento de um cristal líquido nemático em um canal tridimensional; investigação numérica do escoamento em L-canais e escoamento através de uma contração 4:1 e de uma expansão planar 4:1 / The aim of this work is to develop numerical methods capable of simulating nematic liquid crystal flows described by the dynamic Ericksen-Leslie equations. Two numerical techniques have been proposed: a numerical method for solving three-dimensional flows of nematic liquid crystals under strong magnetic fields and a method for simulating flows of nematic liquid crystals in two-dimensional complex geometries. Both methods employ Cartesian coordinates using primitive variables of pressure and velocity. These techniques are based on the GENSMAC (GENeralized-Simplified-Marker-And-Cell) methodology and a detailed description of the equations involved is presented. The resulting governing equations are solved by the finite difference method on a staggered grid. The three-dimensional technique was applied to solve fully developed flow between two paralel plates for which an analytic solution exists. By using this analytic solution, validation and convergence results of the developed numerical technique were obtained. To validate the two-dimensional method developed herein, an analytic solution for steady state flow in a 2D-channel was found which was used to obtain validation and convergence results. The method was then applied to simulate the flow in L-shaped channels, flow through a 4:1 contraction and flow in a 4:1 expansion

The main objective of this thesis is to investigate risk neutral and risk averse approaches to multistage stochastic programming with applications to hydrothermal operation planning problems. The purpose of hydrothermal system operation planning is to define an operation strategy which, for each stage of the planning period, given the system state at the beginning of the stage, produces generation targets for each plant. This problem can be formulated as a large scale multistage stochastic linear programming problem. The energy rationing that took place in Brazil in the period 2001/2002 raised the question of whether a policy that is based on a criterion of minimizing the expected cost (i.e. risk neutral approach) is a valid one when it comes to meet the day-to-day supply requirements and taking into account severe weather conditions that may occur. The risk averse methodology provides a suitable framework to remedy these deficiencies. This thesis attempts to provide a better understanding of the risk averse methodology from the practice perspective and suggests further possible alternatives using robust optimization techniques. The questions investigated and the contributions of this thesis are as follows. First, we suggest a multiplicative autoregressive time series model for the energy inflows that can be embedded into the optimization problem that we investigate. Then, computational aspects related to the stochastic dual dynamic programming (SDDP) algorithm are discussed. We investigate the stopping criteria of the algorithm and provide a framework for assessing the quality of the policy. The SDDP method works reasonably well when the number of state variables is relatively small while the number of stages can be large. However, as the number of state variables increases the convergence of the SDDP algorithm can become very slow. Afterwards, performance improvement techniques of the algorithm are discussed. We suggest a subroutine to eliminate the redundant cutting planes in the future cost functions description which allows a considerable speed up factor. Also, a design using high performance computing techniques is discussed. Moreover, an analysis of the obtained policy is outlined with focus on specific aspects of the long term operation planning problem. In the risk neutral framework, extreme events can occur and might cause considerable social costs. These costs can translate into blackouts or forced rationing similarly to what happened in 2001/2002 crisis. Finally, issues related to variability of the SAA problems and sensitivity to initial conditions are studied. No significant variability of the SAA problems is observed. Second, we analyze the risk averse approach and its application to the hydrothermal operation planning problem. A review of the methodology is suggested and a generic description of the SDDP method for coherent risk measures is presented. A detailed study of the risk averse policy is outlined for the hydrothermal operation planning problem using different risk measures. The adaptive risk averse approach is discussed under two different perspectives: one through the mean-$avr$ and the other through the mean-upper-semideviation risk measures. Computational aspects for the hydrothermal system operation planning problem of the Brazilian interconnected power system are discussed and the contributions of the risk averse methodology when compared to the risk neutral approach are presented. We have seen that the risk averse approach ensures a reduction in the high quantile values of the individual stage costs. This protection comes with an increase of the average policy value - the price of risk aversion. Furthermore, both of the risk averse approaches come with practically no extra computational effort and, similarly to the risk neutral method, there was no significant variability of the SAA problems. Finally, a methodology that combines robust and stochastic programming approaches is investigated. In many situations, such as the operation planning problem, the involved uncertain parameters can be naturally divided into two groups, for one group the robust approach makes sense while for the other the stochastic programming approach is more appropriate. The basic ideas are discussed in the multistage setting and a formulation with the corresponding dynamic programming equations is presented. A variant of the SDDP algorithm for solving this class of problems is suggested. The contributions of this methodology are illustrated with computational experiments of the hydrothermal operation planning problem and a comparison with the risk neutral and risk averse approaches is presented. The worst-case-expectation approach constructs a policy that is less sensitive to unexpected demand increase with a reasonable loss on average when compared to the risk neutral method. Also, we comp are the suggested method with a risk averse approach based on coherent risk measures. On the one hand, the idea behind the risk averse method is to allow a trade off between loss on average and immunity against unexpected extreme scenarios. On the other hand, the worst-case-expectation approach consists in a trade off between a loss on average and immunity against unanticipated demand increase. In some sense, there is a certain equivalence between the policies constructed using each of these methods.

O objetivo desse trabalho é desenvolver métodos numéricos para simular escoamentos de cristais líquidos nemáticos governados pelas equações dinâmicas de Ericksen-Leslie. São apresentados dois métodos numéricos para a simulação de escoamentos de cristais líquidos nemáticos. O primeiro método foi desenvolvido para simular escoamentos tridimensionais de cristais líquidos nemáticos sob efeito de forte campo magnético enquanto que o segundo método foi desenvolvido para a simulação de escoamentos bidimensionais. Utilizando a notação de Einstein, as equações dinâmicas de Ericksen-Leslie são apresentadas. Empregando variáveis primitivas e coordenadas cartesianas, as equações governantes para escoamentos de cristais líquidos nemáticos são derivadas e as formulações matemáticas para a obtenção dos métodos numéricos são apresentadas. As equações descrevendo os métodos numéricos são resolvidas por um método numérico baseado na metodologia GENSMAC3D para o caso tridimensional enquanto que o método bidimensional é baseado na metodologia GENSMAC (GENeralized-Simplified-Marker-And-Cell). Em ambos os métodos, a técnica de diferenças finitas em uma malha deslocada é utilizada. As equações que descrevem as técnicas numéricas desenvolvidas foram incorporadas aos ambientes de simulação Freeflow2D e Freeflow3D. As condições de contorno para cada tipo de contorno são descritas em detalhes. A solução analítica apresentada por Stewart para o escoamento entre duas placas paralelas é utilizada para a validação do método numérico tridimensional. Empregando as hipóteses de escoamento desenvolvido e que o ângulo de orientação do diretor é pequeno, uma solução analítica para o escoamento em um canal bidimensional é encontrada. O método numérico bidimensional é então validado utilizando a solução analítica obtida. Utilizando refinamento de malha, resultados de convergência dos métodos numéricos são apresentados. Os métodos numéricos desenvolvidos nesse trabalho são aplicados para a simulação dos seguintes problemas: escoamento de um cristal líquido nemático em um canal tridimensional; investigação numérica do escoamento em L-canais e escoamento através de uma contração 4:1 e de uma expansão planar 4:1 / The aim of this work is to develop numerical methods capable of simulating nematic liquid crystal flows described by the dynamic Ericksen-Leslie equations. Two numerical techniques have been proposed: a numerical method for solving three-dimensional flows of nematic liquid crystals under strong magnetic fields and a method for simulating flows of nematic liquid crystals in two-dimensional complex geometries. Both methods employ Cartesian coordinates using primitive variables of pressure and velocity. These techniques are based on the GENSMAC (GENeralized-Simplified-Marker-And-Cell) methodology and a detailed description of the equations involved is presented. The resulting governing equations are solved by the finite difference method on a staggered grid. The three-dimensional technique was applied to solve fully developed flow between two paralel plates for which an analytic solution exists. By using this analytic solution, validation and convergence results of the developed numerical technique were obtained. To validate the two-dimensional method developed herein, an analytic solution for steady state flow in a 2D-channel was found which was used to obtain validation and convergence results. The method was then applied to simulate the flow in L-shaped channels, flow through a 4:1 contraction and flow in a 4:1 expansion

Improvement of the current double inverted pendulum model on a cart as well as a new LQG control and swing-up realization are the main goal of this thesis. Movement of the cart is driven by DC motor and gear belt mechanism. At first the control algorithms were simulated in Simulink program and then also implemented into the real system with MF624 card.

In this work, our goal is to prove results on prolongation of solutions, uniform boundedness of solutions, uniform stability as well uniform asymptotic stability (in the classical sense of Lyapunov) for measure differential equations and for dynamic equations on time scales. In order to get our results, we employ the theory of generalized ODEs, since these equations encompass measure differential equations and dynamic equations on time scales. Therefore, to get our results, we start by proving the expected result for abstract generalized ODEs. Then, using the correspondence between the solutions of these equations and the solutions of measure differential equations (see [38]), we extend all the results to these the latter. After that, using the correspondence between the solutions of measure differential equations and the solutions of dynamic equations on time scales (see [21]), we extend all the results to these last equations. Finally, we investigate autonomous generalized ODEs and show that these equations do not enlarge the class of classical autonomous ODEs, even when we consider a more general class of functions as right-hand sides. All the new results presented in this work are contained in papers [16, 17, 18, 19]. / Neste trabalho, nosso objetivo e provar resultados sobre prolongamento de soluções, limitação uniforme de soluções, estabilidade uniforme e estabilidade uniforme assintótica (no sentido clássico de Lyapunov) para equações diferenciais em medida e para equações dinâmicas em escalas temporais. A fim de obter os nossos resultados, empregamos a teoria de EDOs generalizadas, uma vez que estas equações abrangem equações diferenciais em medida e equações dinâmicas em escalas temporais. Portanto, para obter nossos resultados, vamos começar por provar, os resultados que queremos para EDOs generalizadas abstratas. Em seguida, usando a correspondência entre as soluções de EDOs generalizadas e soluções de equações diferenciais em medida (ver [38]), estenderemos os resultados para estas ultimas equações. Depois disso, usando a correspondência entre as soluções de equações diferenciais em medida e as soluções de equações dinâmicas em escalas temporais (ver [21]), estenderemos todos os resultados para estas ultimas equações. Finalmente, investigamos EDOs generalizadas autônomas e mostramos que estas equações não aumentam a classe de EDOs autônomas clássicas, mesmo quando consideramos uma classe mais geral de funções nos lados direitos das equações. Os novos resultados encontrados estão contidos em [16, 17, 18, 19].

In this work, our goal is to prove results on prolongation of solutions, uniform boundedness of solutions, uniform stability as well uniform asymptotic stability (in the classical sense of Lyapunov) for measure differential equations and for dynamic equations on time scales. In order to get our results, we employ the theory of generalized ODEs, since these equations encompass measure differential equations and dynamic equations on time scales. Therefore, to get our results, we start by proving the expected result for abstract generalized ODEs. Then, using the correspondence between the solutions of these equations and the solutions of measure differential equations (see [38]), we extend all the results to these the latter. After that, using the correspondence between the solutions of measure differential equations and the solutions of dynamic equations on time scales (see [21]), we extend all the results to these last equations. Finally, we investigate autonomous generalized ODEs and show that these equations do not enlarge the class of classical autonomous ODEs, even when we consider a more general class of functions as right-hand sides. All the new results presented in this work are contained in papers [16, 17, 18, 19]. / Neste trabalho, nosso objetivo e provar resultados sobre prolongamento de soluções, limitação uniforme de soluções, estabilidade uniforme e estabilidade uniforme assintótica (no sentido clássico de Lyapunov) para equações diferenciais em medida e para equações dinâmicas em escalas temporais. A fim de obter os nossos resultados, empregamos a teoria de EDOs generalizadas, uma vez que estas equações abrangem equações diferenciais em medida e equações dinâmicas em escalas temporais. Portanto, para obter nossos resultados, vamos começar por provar, os resultados que queremos para EDOs generalizadas abstratas. Em seguida, usando a correspondência entre as soluções de EDOs generalizadas e soluções de equações diferenciais em medida (ver [38]), estenderemos os resultados para estas ultimas equações. Depois disso, usando a correspondência entre as soluções de equações diferenciais em medida e as soluções de equações dinâmicas em escalas temporais (ver [21]), estenderemos todos os resultados para estas ultimas equações. Finalmente, investigamos EDOs generalizadas autônomas e mostramos que estas equações não aumentam a classe de EDOs autônomas clássicas, mesmo quando consideramos uma classe mais geral de funções nos lados direitos das equações. Os novos resultados encontrados estão contidos em [16, 17, 18, 19].