Abstract In this literary, we discuss with structure and morphology improvement of GaN epilayer on c-sapphire by multi-step method in molecular-beam epitaxy. Our research is caused for the critical results of defect in GaN epilayer and rough surface morphology. In order to solve these problems we used a novel technique which we called multi-step method. In this thesis, the results of X-ray, SEM, AFM all demonstrated the achievement in our composition. However, we obtained the results of full width of half maxima (FWHM) of (0002) and (10 2) XRD rocking curves with 60~120 arcseconds and 700~ 1200 arcseconds from a series of multi-step samples respectively. Comparing with previous measurement, multi-step method is relatively superior, and the measurement of AFM roughness is under 2 nm from the series of multi-step samples. If we discuss the flat area further, we can get smoother surface which roughness is about 0.4 nm. It is obviously to recognize the flat and rough regions, but in SEM image we made sure that the flat region occupied the greater part of surface. So, in this literary we verified that the method of multi-step can improve the structure and morphology of GaN by molecular-beam epitaxy.

Made available in DSpace on 2014-06-12T17:42:20Z (GMT). No. of bitstreams: 2 arquivo7439_1.pdf: 870168 bytes, checksum: aea24203766388e11d6885b2b79b16f2 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2006 / Universidade Federal de Pernambuco / A atividade de planejamento agregado consiste numa etapa intermediária do planejamento da produção, que busca uma estratégia de atendimento da demanda que direcione as quantidades de itens a serem produzidos em cada alternativa de produção, abrangendo todos os períodos do horizonte de planejamento, os níveis de estoque ao longo do horizonte de planejamento e as variações na força de trabalho para que a demanda prevista seja atendida. Buscando o alinhamento da atividade de planejamento agregado com a estratégia de produção definida, este trabalho apresenta dois modelos de apoio multicritério a decisão para o problema de planejamento agregado, ambos baseados no mesmo princípio, o de estender as prioridades da estratégia de produção para as decisões a serem tomadas no contexto do planejamento agregado da produção. Dessa maneira, o gerente pode fazer o planejamento dos recursos a serem utilizados para atender à demanda priorizando os objetivos de desempenho que melhor refletem os fatores competitivos do negócio. Os modelos propostos neste trabalho buscam fazer com que um problema típico do contexto de planejamento da produção permita que a função produção possa atuar como implementadora da estratégia de produção adotada. A cada estratégia de atendimento da demanda será associado um custo. Portanto, o modelo aqui proposto busca encontrar uma estratégia de atendimento da demanda (obtida através do Planejamento Agregado) que esteja alinhada com as estratégias de produção definidas, respeitando a prioridade e as relações estabelecidas entre os objetivos de desempenho

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Lehmer (1929) analisa matematicamente o método do passo uniforme para construção de quadrados mágicos de ordem impar. Ele divide sua análise em várias etapas. Na primeira delas, envolvendo a discussão de condições necessárias e suficientes para o preenchimento do quadrado pelo método, o autor afirma que se dois números guardarem entre si uma certa relação, eles serão designados a ocupar a mesma célula do quadrado causando seu não preenchimento. A análise do preenchimento pelo método do passo uniforme envolve a resolução de um sistema linear módulo n. Nesse trabalho, discutimos o comportamento das soluções desse sistema quando o método falha no preenchimento. Como consequência, concluímos que números que guardam a relação mencionada nunca ocupam a mesma célula. A análise das condições necessárias e suficientes para obter quadrados mágicos segundo a definição de Lehmer (1929) envolve a resolução de equações de congruências lineares a duas variáveis. Nesse trabalho, detalhamos os resultados de Lehmer (1929). A análise das condições necessárias e suficientes para obtenção de quadrados mágicos, como são reconhecidos usualmente, também envolve a resolução de equações de congruências lineares a duas variáveis. Discutimos o comportamento das soluções dessas equações para obter diagonais principais mágicas. Como consequência, mostramos que diagonais principais mágicas são obtidas se e somente se as coordenadas iniciais guardarem certas relações / Lehmer (1929) mathematically analyzes the uniform step method for constructing magic squares of odd order. He divides his analysis into several steps. In the first, involving a discussion of necessary and sufficient conditions for completing the square, the author states that if two numbers keep a certain relationship to each other, they will be designated to occupy the same cell of the square causing its non fulfillment. The analysis of the uniform step method involves solving a linear system module n. In this monograph, we discuss the behavior of solutions of this system when the method fails in fulfilling the square. Consequently, we conclude that numbers guarding the mentioned relationship never occupy the same cell. The analysis of necessary and sufficient conditions for obtaining magic square (as defined by Lehmer (1929)) involves solving linear congruences in two variables. In this work, we detail the results of Lehmer (1929). The analysis of the necessary and sufficient conditions for magic squares (as usually defined) also involves solving linear congruences in two variables. We discuss the behavior of solutions of these equations to obtain magic main diagonals. Then, we show that magic main diagonals are obtained if and only if the initial coordinates keep certain relationships

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Lehmer (1929) analisa matematicamente o método do passo uniforme para construção de quadrados mágicos de ordem impar. Ele divide sua análise em várias etapas. Na primeira delas, envolvendo a discussão de condições necessárias e suficientes para o preenchimento do quadrado pelo método, o autor afirma que se dois números guardarem entre si uma certa relação, eles serão designados a ocupar a mesma célula do quadrado causando seu não preenchimento. A análise do preenchimento pelo método do passo uniforme envolve a resolução de um sistema linear módulo n. Nesse trabalho, discutimos o comportamento das soluções desse sistema quando o método falha no preenchimento. Como consequência, concluímos que números que guardam a relação mencionada nunca ocupam a mesma célula. A análise das condições necessárias e suficientes para obter quadrados mágicos segundo a definição de Lehmer (1929) envolve a resolução de equações de congruências lineares a duas variáveis. Nesse trabalho, detalhamos os resultados de Lehmer (1929). A análise das condições necessárias e suficientes para obtenção de quadrados mágicos, como são reconhecidos usualmente, também envolve a resolução de equações de congruências lineares a duas variáveis. Discutimos o comportamento das soluções dessas equações para obter diagonais principais mágicas. Como consequência, mostramos que diagonais principais mágicas são obtidas se e somente se as coordenadas iniciais guardarem certas relações / Lehmer (1929) mathematically analyzes the uniform step method for constructing magic squares of odd order. He divides his analysis into several steps. In the first, involving a discussion of necessary and sufficient conditions for completing the square, the author states that if two numbers keep a certain relationship to each other, they will be designated to occupy the same cell of the square causing its non fulfillment. The analysis of the uniform step method involves solving a linear system module n. In this monograph, we discuss the behavior of solutions of this system when the method fails in fulfilling the square. Consequently, we conclude that numbers guarding the mentioned relationship never occupy the same cell. The analysis of necessary and sufficient conditions for obtaining magic square (as defined by Lehmer (1929)) involves solving linear congruences in two variables. In this work, we detail the results of Lehmer (1929). The analysis of the necessary and sufficient conditions for magic squares (as usually defined) also involves solving linear congruences in two variables. We discuss the behavior of solutions of these equations to obtain magic main diagonals. Then, we show that magic main diagonals are obtained if and only if the initial coordinates keep certain relationships

Les composants semi-conducteurs de puissance sont aujourd'hui au c?ur des systèmes de conversion d'énergie et sont de plus en plus employés dans le domaine des transports, notamment dans des applications critiques induites par l'émergence des véhicules hybrides et d'avions plus électriques. Durant l'exploitation des systèmes de conversion d'énergie, des contraintes significatives sont imposées aux composants semi-conducteurs de puissance, dégradant ainsi leur fonctionnement. Dans une application critique, ces dégradations peuvent activer la défaillance d'un système électrique et ainsi avoir des conséquences graves d'un point de vue économique et de sécurité. Il existe alors une forte demande concernant une compréhension des modes de défaillances et des mécanismes de vieillissement des composants semi-conducteurs de puissance. Il en est de même pour le développement de nouvelles techniques de caractérisations pour le suivi de leur vieillissement. Le suivi de l'évolution de paramètres de l'oxyde de grille de véhicules tests par le biais de la méthode Capacité-Tension ou C(V) - couramment employée en micro-électronique - et de la méthode de l'onde thermique ou MOT - développée au sein du Groupe Énergie et Matériaux de l'IES -, ainsi que leur adaptation à des composants semi-conducteurs de puissance, constituent l'essentiel du travail de cette thèse. Le couplage de la MOT à la C(V) a permis de localiser sommairement les charges injectées dans l'oxyde de grille des véhicules tests lorsqu'ils ont été soumis à des contraintes électriques similaires à celles subies dans les systèmes de conversion d'énergie. / Power semi-conductor devices are increasingly used as key parts of embedded power conversion systems in critical applications such as aerospace industry and ground transport. In such critical applications, these devices are submitted to harsh electrical, thermal and mechanical environments stresses which may significantly alter their reliability. An embedded power conversion system failure due to a power semi-conductor device breakdown may induce catastrophic results in terms of human safety, as well as economical dimensions. There is, indeed, a continuous demand on an increasing knowledge concerning the failure modes and the ageing mechanisms of power semi-conductor devices, as well as for development of new characterization techniques for ageing monitoring. The greatest part of the present work is focused on the monitoring of gate oxide properties evolutions of samples structures using the Capacitance-Voltage method (C-V method) -mainly employed in microelectronics- and the Thermal Step Method (TSM) -developed in Energy and Materials Group of IES-, as well as applying them to power semi-conductor devices. Coupling TSM and C-V method has allowed to approximately locate injected charges in the gate oxide of sample devices when submitted to electrical stresses comparable to the ones submitted to power semi-conductor devices.

Effects of drugs are in clinical trials often measured on categorical scales. These measurements are increasingly being analyzed using mixed-effects logistic regression. However, the experience with such analyzes is limited and only a few models are used. The aim of this thesis was to investigate the performance and improve the use of models and methods for mixed-effects categorical data analysis. The Laplacian method was shown to produce biased parameter estimates if (i) the data variability is large or (ii) the distribution of the responses is skewed. Two solutions are suggested; the Gaussian quadrature method and the back-step method. Two assumptions made with the proportional odds model have also been investigated. The assumption with proportional odds for all categories was shown to be unsuitable for analysis of data arising from a ranking scale of effects with several underlying causes. An alternative model, the differential odds model, was developed and shown to be an improvement, in regard to statistical significance as well as predictive performance, over the proportional odds model for such data. The appropriateness of the likelihood ratio test was investigated for an analysis where dependence between observations is ignored, i.e. performing the analysis using the proportional odds model. The type I error was found to be affected; thus assessing the actual critical value is prudent in order to verify the statistical significance level. An alternative approach is to use a Markov model, in which dependence between observations is incorporated. In the case of polychotomous data such model may involve considerable complexity and thus, a strategy for the reduction of the time-consuming model building with the Markov model and sleep data is presented. This thesis will hopefully contribute to a more confident use of models for categorical data analysis within the area of pharmacokinetic and pharmacodynamic modelling in the future.

Immersed boundary methods are a class of techniques in computational fluid dynamics where the Navier-Stokes equations are simulated on a computational grid that does not conform to the interfaces in the domain of interest. This facilitates the simulation of flows with complex moving and deforming geometries without considerable effort wasted in generating the mesh. The first part of this dissertation is concerned with the aerodynamics of the cross-section of a species of flying snake, Chrysopelea paradisi (paradise tree snake). Past experiments have shown that the unique cross-section of this snake, which can be described as a lifting bluff body, produces an unusual lift curve--with a pronounced peak in lift coefficient at an angle of attack of 35 degrees for Reynolds numbers 9000 and beyond. We studied the aerodynamics of the cross-section using a 2-D immersed boundary method code. We were able to qualitatively reproduce the spike in the lift coefficient at the same angle of attack for flows beyond a Reynolds number of 2000. This phenomenon was associated with flow separation at the leading edge of the body that did not result in a stall. This produced a stronger vortex and an associated reduction in pressure on the dorsal surface of the snake cross-section, which resulted in higher lift. The second part of this work deals with the analysis of the direct forcing method, which is a popular immersed boundary method for flows with rigid boundaries. We begin with the fully discretized Navier-Stokes equations along with the appropriate boundary conditions applied at the solid boundary, and derive the fractional step method as an approximate block LU decomposition of this system. This results in an alternate formulation of the direct forcing method that takes into consideration mass conservation at the immersed boundaries and also handles the pressure boundary conditions more consistently. We demonstrate that this method is between first and second-order accurate in space when linear interpolation is used to enforce the boundary conditions on velocity. We then develop a theory for the order of accuracy of the direct forcing method with linear interpolation. For a simple 1-D case, we show that the method can converge at a range of rates for different locations of the solid body with respect to the mesh. But this effect averages out in higher dimensions and results in a scheme that has the same order of accuracy as the expected order of accuracy of the interpolation at the boundary. The discrete direct forcing method for the Navier-Stokes equations exhibits an order of accuracy between 1 and 2 because the velocities at the boundary are linearly interpolated, but the resulting boundary conditions on the pressure gradient turn out to be only first-order accurate. We recommend linearly interpolating the pressure gradient as well to make the method fully second-order accurate. We have also developed two open source codes in the course of these studies. The first, cuIBM, is a two-dimensional immersed boundary method code that runs on a single GPU. It can simulate incompressible flow around rigid bodies with prescribed motion. It is based on the general idea of a fractional step method as an approximate block LU decomposition, and can incorporate any type of immersed boundary method that can be made to fit within this framework. The second code, PetIBM, can simulate both two and three-dimensional incompressible flow and runs in parallel on multiple CPUs. Both codes have been validated using well-known test cases.

L'augmentation des besoins en énergie électrique et l'éloignement croissant des lieux de production par rapport aux centres de consommation impulsent le développement du transport d'énergie en courant continu. Dans le cas des câbles haute tension à courant continue (HTCC) à isolation polymère, la problématique de la fiabilité est liée à l'établissement, sous l'effet des fortes contraintes électrothermiques, de zones de charges électriques dans le diélectrique et au niveau des interfaces isolant/compound semi-conducteur. De telles accumulations de charges (dites charges « d'espace » car reparties dans un espace isolant) peuvent faire vieillir prématurément les isolations, voire les faire claquer de manière intempestive. La mise en œuvre de nouveaux matériaux et l’optimisation des structures isolantes pour câbles HTCC nécessitent ainsi le suivi des zones de charges d’espace avec la plus grande précision. Il est alors nécessaire de développer des techniques de mesure non destructives, telle que la méthode de l’onde thermique (MOT), basée sur l’application d’un faible échelon de température à une structure isolante et sur la mesure d’un courant transitoire provoqué par la redistribution des charges d’influence aux électrodes.Ce travail porte sur la faisabilité et la mise en œuvre expérimentale d’une installation, basée sur le principe de la MOT, visant à mesurer les charges d’espace dans des échantillons isolants comportant des couches semi-conductrices, avec une résolution la plus proche possible du degré d’homogénéité des interfaces (de l’ordre du micromètre).Après avoir passé en revue les problématiques des diélectriques soumis à des forts champs continus et les méthodes de mesure de charges d’espace existantes, le mémoire présente divers aspects et grandeurs liés au principe de la MOT, ainsi qu’à la définition et à l’estimation des résolutions spatiales. Des simulations analytiques et numériques sont par la suite menées pour étudier les apports d’une mise en œuvre de la MOT sur des structures isolantes de polyéthylène réticulé chimiquement de 100 µm d’épaisseur avec des électrodes semi-conductrices de 30 µm. Elles montrent que l’application d’échelons de température d’amplitudes n’affectant pas les états électrique et de surface des matériaux se traduit par des signaux de mesure de plusieurs nano ampères pour des variations de champ résiduel de l’ordre du kV/mm par micron. La génération de ces signaux, nécessaires à des mesures ayant une dynamique suffisante et à des résolutions s’approchant du micron, requière des échanges thermiques hautement efficaces entre la source de chaleur (liquide caloporteur) et l’isolant. Une étude par simulation multi-physique bidimensionnelle est réalisée afin d’analyser le transfert de chaleur par contact direct entre un liquide caloporteur et un échantillon-type. Elle permet de définir et d’optimiser une structure innovante de diffuseur thermique et dans laquelle l’échange de chaleur entre le fluide et l’échantillon s’opère par contact direct, assurant ainsi une efficacité bien supérieure aux structures existantes.Le développement d’un outil de mesure par la MOT, basé sur les conclusions des travaux de simulation, est par la suite présentée. Il associe un système hydropneumatique, un diffuseur haute efficacité favorisant la dynamique du transfert thermique et un système de capteurs, en augmentant ainsi l’amplitude des signaux, la reproductibilité et la précision de la mesure. Des mesures d’étalonnage sur des échantillons cibles montrent, par rapport aux résolutions disponibles sur ce type de structure (autour de 10 µm), des améliorations d’un facteur 2 à 5 pour la résolution de positionnement et une résolution de discernement proche de l’état de l’art. L’analyse critique du banc développé, corroborée aux prédictions des simulations, met également en évidence la marge de progression sensible de l’outil, dont les évolutions proposées permettront d’accroître les performances. / The increasing needs of electric power and the placement of power plants at more and more remote locations with respect to the users promote the development of electric power transport by DC submarine or terrestrial links. In the case of high voltage direct current (HVDC) cables with polymeric insulation, reliability is strongly affected by the development, under high electrical and thermal stress, of electric charges in the bulk of the dielectric and at the insulator/semiconductor interfaces. These accumulations of charges (called space charges as they are distributed in an insulating space) may lead to premature ageing and breakdown. The setup of new materials and the optimization of insulating structures for HVDC cables require a precise follow-up of the space charge zones. It is therefore necessary to develop non-destructive space charge measurement techniques, as the thermal step method (TSM), which is based on the application of a low temperature step to an insulating structure and on the measurement of a transient current due to the redistribution of influence charges at electrodes.The present work concerns the feasibility and the experimental set up of a device, based on the principle of the TSM, aiming to measure the space charges in insulating samples with semi-conducting electrodes, with a resolution approaching the degree of homogeneity of the interfaces (i.e., of micrometric order).After having reviewed the problematic of the dielectrics subjected to high dc fields and the existing space charge measurement methods, this dissertation presents several aspects and parameters related to the principle of the TSM, as well as to the definition and to the estimation of spatial resolutions. Analytical and numerical simulations are then carried out to study the contributions of a TSM-based setup on insulating structures composed of 100 µm-thick cross-linked polyethylene slabs provided with 30 µm-thick semiconducting electrodes. They show that the application of temperature steps, with amplitudes that do not affect the electrical and surface states of the materials, leads to measurement signals of several nano amperes for variations of the remnant electric field of the order of the kV/mm per micron. Highly effective thermal exchanges between the heat source (heating or coolant liquid) and the insulator are required to generate such signals, needed for measurements of sufficient dynamics and for resolutions approaching the micrometer. A bi-dimensional multi-physics simulation study is made, in order to analyze the heat transfer through a direct contact between the coolant liquid and a sample of the aimed type. The study allows to define and to optimize an innovating structure of thermal diffuser, where the heat exchanges operates by direct contact, thus providing a much better efficiency than the existing structures.The development of a TSM-based measurement tool, using the fallouts of the simulations, is then presented. It associates a hydro pneumatic system, a high efficiency diffuser favoring the dynamics of the thermal transfer and a sensor system, thus increasing the amplitude of the signals, the reproducibility and the accuracy of the measurements. Calibration measurements on the aimed samples show, with respect to the resolutions available on this type of structures (close to 10 µm), enhancements by a factor of 2 to 5 for the positioning resolution an a discerning resolution close to the state of the art. The critical analysis of the developed bench, corroborated to the predictions of the simulations, also puts into focus a significant room for improvement of the tool, for which evolutions proposed in this work would allow to enhance the performance.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-03-07T11:11:33Z No. of bitstreams: 1 carlosrobertolimaladeira.pdf: 2482685 bytes, checksum: b90ffa199573e38ddbce8d8ac0283585 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-03-07T15:03:08Z (GMT) No. of bitstreams: 1 carlosrobertolimaladeira.pdf: 2482685 bytes, checksum: b90ffa199573e38ddbce8d8ac0283585 (MD5) / Made available in DSpace on 2017-03-07T15:03:08Z (GMT). No. of bitstreams: 1 carlosrobertolimaladeira.pdf: 2482685 bytes, checksum: b90ffa199573e38ddbce8d8ac0283585 (MD5) Previous issue date: 2014-02-28 / Estimar parâmetros de modelos dinâmicos de sistemas biológicos usando séries temporais é cada vez mais importante, pois uma quantidade imensa de dados experimentais está sendo mensurados pela biologia molecular moderna. Uma abordagem de resolução baseada em problemas inversos pode ser utilizada na solução deste tipo de problema. A escolha do modelo matemático é uma tarefa importante, pois vários modelos podem ser utilizados, apresentando níveis diversos de precisão em suas representações. A Teoria dos Sistemas Bioquímicos (TSB) faz uso de equações diferenciais ordinárias e expansões de séries de potências para representar processos bioquímicos. O Sistema S é um dos modelos usados pela TSB que permite a transformação do sistema original de equações diferenciais em um sistema algébrico desacoplado, facilitando a solução do problema inverso. Essa transformação pode comprometer a qualidade da resposta se o valor das derivadas nos pontos das séries temporais não for obtidos com precisão. Para estimar as derivadas pretende-se explorar o método do passo complexo, que apresenta vantagens em relação ao método das diferenças finitas, mais conhecido e utilizado. A partir daí pode então ser realizada a busca pelas variáveis que definirão as equações do sistema. O método da Regressão Alternada é um dos mais rápidos para esse tipo de problema, mas a escolha inicial dos parâmetros possui influência em seu resultado, que pode até mesmo não ser encontrado. Pretende-se avaliar o método da Entropia Cruzada, que possui a vantagem de realizar buscas globais e talvez por esse motivo a escolha dos parâmetros inicias não cause tanta influência nos resultados. Além disso, será avaliado um método híbrido que fará uso das principais vantagens do método da Regressão Alternada e do Entropia Cruzada para resolver o problema. Experimentos numéricos sistematizados serão realizados tanto para a etapa de estimativa das derivadas quanto para a etapa de otimização para obtenção dos parâmetros das equações do sistema. / Estimating parameters of dynamic models of biological systems using time series is becoming very important because a huge amount of experimental data is being measured by modern molecular biology. A resolution-based approach on inverse problems can be used in solving this type of problem. The choice of the mathematical model is an important task, since many models can be used, with varying levels of accuracy in their representations. The Biochemical Systems Theory (BST) makes use of ordinary differential equations and power series expansions to represent biochemical processes. The S-system is one of the models used by BST that allows the transformation of the original system of differential equations in a decoupled system of algebric equations, favouring the solution of the inverse problem. This transformation can compromise the quality of the response if the value of the derivatives at points of time series are not obtained accurately. To estimate the derivatives we intend to explore the complex-step method, which has advantages over the finite difference method, best known and used . So the search for the variables that define the equations of the system can be performed. The Alternating Regression method is one of the fastest for this type of problem, but the initial choice of parameters has influence on its performance, which may not even be found. We intend to evaluate the Cross-entropy method, which has the advantage of performing global searches and for this reason the choice of the initial search parameters does not cause as much influence on the results. Also, will be assessed a hybrid method that makes use of the main advantages of Alternating Regression and Cross-entropy to solve the problem. Systematic numerical experiments will be conducted for both the step of estimating derivatives as for the optimization step to estimate the variables of the equations of the system.

Dans cette thèse, une nouvelle méthode de frontières immergées a été développée pour la simulation d'interaction fluide-structure, appelée la méthode de frontières immergées mobiles (en langage anglo-saxon: MIBM). L'objectif principal de cette nouvelle méthode est de déplacer arbitrairement les solides à géométrie complexe dans un fluide visqueux incompressible, sans remailler le domaine fluide. Cette nouvelle méthode a l'avantage d'imposer la condition de non-glissement à l'interface d'une manière exacte via une force sans introduire des constantes artificielles modélisant la structure rigide. Cet avantage conduit également à la satisfaction de la condition CFL avec un pas de temps plus grand. Pour un calcul précis de la force induite par les frontières mobiles, un système linéaire a été introduit et résolu par la méthode de gradient conjugué. La méthode proposée peut être intégrée facilement dans des solveurs résolvant les équations de Navier-Stokes. Dans ce travail la MIBM a été mise en œuvre en couplage avec un solveur fluide utilisant une méthode de projection adaptée pour obtenir des solutions d'ordre deux en temps et en espace. Le champ de pression a été obtenu par l'équation de Poisson qui a été résolue à l'aide de la méthode du gradient conjugué préconditionné par la méthode multi-grille. La combinaison de ces deux méthodes a permis un gain de temps considérable par rapport aux méthodes classiques de la résolution des systèmes linéaires. De plus le code de calcul développé a été parallélisé sur l'unité graphique GPU équipée de la bibliothèque CUDA pour aboutir à des hautes performances de calcul. Enfin, comme application de nos travaux sur la MIBM, nous avons étudié le couplage "fort" d'interaction fluide-structure (IFS). Pour ce type de couplage, un schéma implicite partitionné a été adopté dans lequel les conditions à l'interface sont satisfaites via un schéma de type "point fixe". Pour réduire le temps de calcul inhérent à cette application, un nouveau schéma de couplage a été proposé pour éviter la résolution de l'équation de Poisson durant les itérations du "point fixe". Cette nouvelle façon de résoudre les problèmes IFS a montré des performances prometteuses pour des systèmes en IFS complexe. / In this thesis a novel non-body conforming mesh formulation is developed, called the moving immersed boundary method (MIBM), for the numerical simulation of fluid-structure interaction (FSI). The primary goal is to enable solids of complex shape to move arbitrarily in an incompressible viscous fluid, without fitting the solid boundary motion with dynamic meshes. This novel method enforces the no-slip boundary condition exactly at the fluid-solid interface with a boundary force, without introducing any artificial constants to the rigid body formulation. As a result, large time step can be used in current method. To determine the boundary force more efficiently in case of moving boundaries, an additional moving force equation is derived and the resulting system is solved by the conjugate gradient method. The proposed method is highly portable and can be integrated into any fluid solver as a plug-in. In the present thesis, the MIBM is implemented in the fluid solver based on the projection method. In order to obtain results of high accuracy, the rotational incremental pressure correction projection method is adopted, which is free of numerical boundary layer and is second order accurate. To accelerate the calculation of the pressure Poisson equation, the multi-grid method is employed as a preconditioner together with the conjugate gradient method as a solver. The code is further parallelized on the graphics processing unit (GPU) with the CUDA library to enjoy high performance computing. At last, the proposed MIBM is applied to the study of two-way FSI problem. For stability and modularity reasons, a partitioned implicit scheme is selected for this strongly coupled problem. The interface matching of fluid and solid variables is realized through a fixed point iteration. To reduce the computational cost, a novel efficient coupling scheme is proposed by removing the time-consuming pressure Poisson equation from this fixed point interaction. The proposed method has shown a promising performance in modeling complex FSI system.