A interação entre fluidos e estruturas caracteriza um problema multi-físico não linear e está presente numa grande variedade de áreas da engenharia. Este trabalho apresenta o desenvolvi mento de ferramentas computacionais com base no Método dos Elementos Finitos (MEF) para a análise de interação fluido-estrutura (IFE) considerando escoamentos com baixas velocidades. Dada a interdisciplinaridade do tema, se faz necessário o estudo em três diferentes assuntos: a dinâmica das estruturas computacional, a dinâmica dos fluidos computacional, e o problema de acoplamento. No caso da dinâmica das estruturas empregar-se um elemento finito que seja adequado para a simulação de problemas de IFE, que claramente demandam uma análise não linear geométrica, optando-se pelo emprego de uma formulação descrita em posições, a qual evita problemas relativos à aproximação de rotações finitas. Quanto à dinâmica dos fluidos computacional, é empregado um método estável e ao mesmo tempo sensível à movimentação da estrutura, utilizando a descrição Lagrangeana-Euleriana Arbitrária (ALE). Os casos considerados neste trabalho, assim como muitos dos problemas de engenharia, ocorrem com escoamentos em baixas velocidades, implicando na incompressibilidade do fluido, o que demanda, para um método estável, a utilização de elementos que atendam à condição de Ladyzhenskaya-Babuska-Brezzi (LBB). Além disso, é necessário também o emprego de métodos que consigam neutralizar as variações espúrias decorrentes da não-linearidade de possíveis escoamentos com convecção dominante e que surgem com a aplicação do processo clássico de Galerkin. Para superar esse problema, é aplicado o método Streamline-Upwind/Petrov-Galerkin (SUPG), que adiciona difusividade artificial na direção do escoamento, controlando a amplitude dos termos convectivos. No que se refere ao acoplamento fluido-casca, buscam-se modularidade e versatilidade adotando-se o modelo particionado. O modelo de acoplamento implementado garante ainda a utilização de malhas do fluido e da estrutura sem a necessidade de coincidência de nós. / Interaction between fluids and structures characterizes a nonlinear multi-physics problem presente in a wide range of engineering fields. This works presets the development of computational tools based on finite element method (FEM) for fluid-structure interaction (FSI) analysis considering low speed flows (incompressible), as a great part of the engineering problems. Given the topic multidisciplinary nature, it is necessary to study three different subjects: the computational structural dynamics, the computational fluid mechanics and the coupling problem. Regarding structural mechanics, we seek to employ a finite element adequate to FSI simulation, what clearly demands a geometric nonlinear analysis. We chose to employ shell elements with formulation in terms of positions, which avoids problems related to finite rotations approximations. Concerning computational fluid dynamics, we employ a stable method, at same time sensible o structural movements, which is written in the arbitrary Lagrangian-Eulerian (ALE) description. The flow incompressibility demands, for a stable method, the use of elements according to the Ladyzhenskaya-Bbuska-Brezzi (LBB) condition. It is also necessary to employ methods able to neutralize the spurious variations that appears from convection dominated flows when applying the standard Galerking method. In order to overcome this problem, we apply the Streamline-Upwind/Petrov-Galerkin (SUPG) method, which adds artificial diffusivity to the streamline direction, controlling spurious variations. Considering the fluid-shell coupling, we seek modularity and versatility, adopting the partitioned model. The developed coupling model ensure the use of fluid and structure meshes with no need for matching nodes.

Dans cette thèse nous étudions le problème d'ordonnancement temps réel multiprocesseur préemptif avec prise en compte du coût exact du système d'exploitation. Ce coût est formé de deux parties : une partie facile à déterminer, correspondant au coût de l'ordonnanceur et une partie difficile à déterminer, correspondant au coût de la préemption. Cette difficulté est due au fait qu'une préemption peut en engendrer une autre, pouvant ainsi créer un phénomène d'avalanche. Dans un premier temps, nous avons étudié l'ordonnancement hors ligne multiprocesseur de tâches indépendantes avec prise en compte du coût exact de la préemption et proposé une analyse d'ordonnançabilité fondée sur une heuristique d'ordonnancement multiprocesseur. Cette heuristique utilise la stratégie d'ordonnancement multiprocesseur par partitionnement. Pour prendre en compte le coût exact de la préemption sur chaque processeur nous avons utilisé la condition d'ordonnançabilité proposée par Meumeu et Sorel. Cette condition d'ordonnançabilité pour des tâches à priorités fixes, est basée sur une opération binaire d'ordonnancement qui permet de compter le nombre exact de préemption et d'ajouter leur coût dans l'analyse d'ordonnançabilité des tâches. L'heuristique proposée permet de maximiser le facteur d'utilisation restant afin de répartir équitablement les tâches sur les processeurs et de réduire leur temps de réponse. Elle produit une table d'ordonnancement hors ligne. Dans un second temps, nous avons étudié l'ordonnancement hors ligne multiprocesseur de tâches dépendantes avec prise en compte du coût exact de la préemption. Puisque la condition d'ordonnançabilité utilisée pour ordonnancer les tâches indépendantes ne s'applique qu'à des tâches à priorités fixes, elle ne permet pas de gérer les inversions de priorités que peuvent entraîner les tâches dépendantes. Nous avons donc proposé une nouvelle condition d'ordonnançabilité pour des tâches à priorités dynamiques. Elle prend en compte le coût exact de la préemption et les dépendances sans aucune perte de données. Ensuite en utilisant toujours la stratégie d'ordonnancement par partitionnement, nous avons proposé pour des tâches dépendantes une heuristique d'ordonnancement multiprocesseur qui réutilise cette nouvelle condition d'ordonnançabilité au niveau de chaque processeur. Cette heuristique d'ordonnancement prend en compte les coûts de communication inter-processeurs. Elle permet aussi de minimiser sur chaque processeur le makespan (temps total d'exécution) des tâches. Cette heuristique produit pour chaque processeur une table d'ordonnancement hors ligne contenant les dates de début et de fin de chaque tâches et de chaque commmunication inter-processeur. En supposant que nous avons une architecture multiprocesseur de type dirigée par le temps (Time-Triggered) pour laquelle tous les processeurs ont une référence de temps unique, nous avons proposé pour chacun des processeurs un ordonnanceur en ligne qui utilise la table d'ordonnancement produite lors de l'ordonnancement hors ligne. Cet ordonnanceur en ligne a l'avantage d'avoir un coût constant qui de plus est facile à déterminer de manière exacte. En effet il correspond uniquement au temps de lecture dans la table d'ordonnancement pour obtenir la tâche sélectionnée lors de l'analyse d'ordonnançabilité hors ligne, alors que dans les ordonnanceurs classiques en ligne ce coût correspond à mettre à jour la liste des tâches qui sont dans l'état prêt à l'exécution puis à sélectionner une tâche selon un algorithme, par exemple RM, DM, EDF, etc. Il varie donc avec le nombre de tâches prêtes à s'exécuter qui change d'une invocation à l'autre de l'ordonnanceur. C'est ce coût qui est utilisé dans les analyses d'ordonnançabilités évoquées ci-dessus. Un autre avantage est qu'il n'est pas nécessaire de synchroniser l'accès aux mémoires de données partagées par plusieurs tâches, car cette synchronisation a été déjà effectuée lors de l'analyse d'ordonnançabilité hors ligne. / In this thesis we studied the problem of multiprocessor preemptive real-time scheduling taking into account the exact cost of the operating system (OS). This cost is composed of two parts: a part easy to determine, corresponding to the scheduler cost and another part difficult to determine, corresponding to the preemption cost. This difficulty is due to the fact that a preemption can involve another one, being able to so create an avalanche phenomenon. First, we studied the off-line multiprocessor real-time scheduling of independent tasks taking into account the exact preemption cost. We proposed a schedulability analysis based on a multiprocessor scheduling heuristic. This heuristic uses the partitioned multiprocessor scheduling approach. In order to take into account the exact preemption cost on every processor we use the schedulability condition proposed by Meumeu and Sorel. This schedulability condition for fixed priorities tasks, is based on a binary scheduling operation which counts the exact number of preemptions and add their cost in the schedulability analysis. The proposed heuristic maximizes the remaining utilization factor to fairly distribute the tasks on processors and to reduce their response time. It produces an off-line scheduling table. Secondly, we studied the off-line multiprocessor real-time scheduling of dependent tasks taking into account the exact preemption cost. Because the schedulability condition used for scheduling independent tasks can be applied only to fixed priorities tasks, it does not allow to manage priorities inversions that are involved by dependent tasks. We proposed a new schedulability condition for dependent tasks which enables fixed and dynamic priorities. This schedulability condition takes into account the exact preemption cost and dependences between tasks without any loss of data. Always with the partitioned scheduling approach, we proposed for dependent tasks a multiprocessor scheduling heuristic which reuses, on every processor, the schedulability condition proposed previously. In addition, this scheduling heuristic takes into account the interprocessors communication costs. It also minimizes on every processor the makespan (total execution time of the tasks on all the processors). This heuristic produces for every processor an off-line scheduling table. Supposing that we have a time-triggered multiprocessor architecture such that all the processors have a unique time reference, we proposed for every processor an on-line scheduler which uses the scheduling table produced during the off-line schedulability analysis. This on-line scheduler has the advantage to have a constant cost that is easy to determine exactly.Indeed, this cost corresponds only to the time necessary to read in the scheduling table the task selected for execution. In the on-line classical scheduler, this cost corresponds to the time necessary to update the list of ready tasks in order to select a task, according to a given scheduling algorithm, for example RM, DM, EDF, etc. In this case, the cost for selecting a task varies with the number of ready tasks which changes from an invocation of the scheduler to another one. Another advantage of the proposed on-line scheduler is that it is not necessary to synchronize the access to the data shared by several tasks, because this synchronization was already done during the off-line schedulability analysis.

Time management is one of the critical modules of safety-critical systems. Applications need strong assurance from the operating system that their hard real-time requirements are met. Partitioned system has recently evolved as a means to provide protection to safety critical applications running on an Avionics computer resource. Each partition has an application running strictly for a specified duration. These applications use the CPU on a cyclic basis. Applications running on a real-time systems request the service of time management in one way or the other. An application may request for a time-out while waiting for a resource, may voluntarily relinquish the CPU for some delay time or may have deadline before which it is expected to complete its tasks. These requests must be handled in a deterministic and accurate way with lower overheads. Time management within an operating system uses the hardware timers to service the time-out requests. The three well-known approaches for handling timer requests are tick-based, one-shot and firm timer. Traditionally tick-based has been the most popular approach that relies on periodic interrupt timer, although it has a poor accuracy. One-shot timer approach provides better accuracy as the timer interrupt can be generated exactly when required. Firm timers use soft timers in combination with one-shot timer wherein the expired timers are checked at strategic points in the kernel. The thesis compares the performance of these three approaches for partitioned systems and provides an insight about the suitability of the approaches. The thesis presents tick-based and one-shot timer algorithms that handle time-out requests of real-time applications running on a partitioned system by adhering to time partitioning rules. It compares the performance of these algorithms. It presents an one-shot timer algorithm named hierarchical multiple linked lists and the experimental results proves that the algorithm performs better than other conventional linked list based one-shot timer algorithms. The thesis also analyzes the timing behavior of real-time applications for partitioned systems. The hard real-time system under consideration is avionics system and an indigenously developed ARINC-653 compliant real-time operating system has been used to measure the performance.

This work makes significant contributions in the field of sufficient schedulability tests for rate-monotonic scheduling (RMS) and their application to partitioned RMS. Goal is the maximization of possible utilization in worst or average case under a given number of processors. This scenario is more realistic than the dual case of minimizing the number of necessary processors for a given task set since the hardware is normally fixed. Sufficient schedulability tests are useful for quick estimates of task set schedulability in automatic system-synthesis tools and in online scheduling where exact schedulability tests are too slow. Especially, the approach of Accelerated Simply Periodic Task Sets (ASPTSs) and the concept of circular period similarity are cornerstones of improvements in the success ratio of such schedulability tests. To the best of the author's knowledge, this is the first application of circular statistics in real-time scheduling. Finally, the thesis discusses the use of sharp total utilization thresholds for partitioned EDF. A constant-time admission control is enabled with a controlled residual risk. / Diese Arbeit liefert entscheidende Beiträge im Bereich der hinreichenden Planbarkeitstests für ratenmonotones Scheduling (RMS) und deren Anwendung auf partitioniertes RMS. Ziel ist die Maximierung der möglichen Last im Worst Case und im Average Case bei einer gegebenen Zahl von Prozessoren. Dieses Szenario ist realistischer als der duale Fall der Minimierung der Anzahl der notwendigen Prozessoren für eine gegebene Taskmenge, da die Hardware normalerweise fixiert ist. Hinreichende Planbarkeitstests sind für schnelle Schätzungen der Planbarkeit von Taskmengen in automatischen Werkzeugen zur Systemsynthese und im Online-Scheduling sinnvoll, wo exakte Einplanungstests zu langsam sind. Insbesondere der Ansatz der beschleunigten einfach-periodischen Taskmengen und das Konzept der zirkulären Periodenähnlichkeit sind Eckpfeiler für Verbesserungen in der Erfolgsrate solcher Einplanungstests. Nach bestem Wissen ist das die erste Anwendung zirkulärer Statistik im Echtzeit-Scheduling. Schließlich diskutiert die Arbeit plötzliche Phasenübergänge der Gesamtlast für partitioniertes EDF. Eine Zugangskontrolle konstanter Zeitkomplexität mit einem kontrollierten Restrisiko wird ermöglicht.

A interação entre fluidos e estruturas caracteriza um problema multi-físico não linear e está presente numa grande variedade de áreas da engenharia. Este trabalho apresenta o desenvolvi mento de ferramentas computacionais com base no Método dos Elementos Finitos (MEF) para a análise de interação fluido-estrutura (IFE) considerando escoamentos com baixas velocidades. Dada a interdisciplinaridade do tema, se faz necessário o estudo em três diferentes assuntos: a dinâmica das estruturas computacional, a dinâmica dos fluidos computacional, e o problema de acoplamento. No caso da dinâmica das estruturas empregar-se um elemento finito que seja adequado para a simulação de problemas de IFE, que claramente demandam uma análise não linear geométrica, optando-se pelo emprego de uma formulação descrita em posições, a qual evita problemas relativos à aproximação de rotações finitas. Quanto à dinâmica dos fluidos computacional, é empregado um método estável e ao mesmo tempo sensível à movimentação da estrutura, utilizando a descrição Lagrangeana-Euleriana Arbitrária (ALE). Os casos considerados neste trabalho, assim como muitos dos problemas de engenharia, ocorrem com escoamentos em baixas velocidades, implicando na incompressibilidade do fluido, o que demanda, para um método estável, a utilização de elementos que atendam à condição de Ladyzhenskaya-Babuska-Brezzi (LBB). Além disso, é necessário também o emprego de métodos que consigam neutralizar as variações espúrias decorrentes da não-linearidade de possíveis escoamentos com convecção dominante e que surgem com a aplicação do processo clássico de Galerkin. Para superar esse problema, é aplicado o método Streamline-Upwind/Petrov-Galerkin (SUPG), que adiciona difusividade artificial na direção do escoamento, controlando a amplitude dos termos convectivos. No que se refere ao acoplamento fluido-casca, buscam-se modularidade e versatilidade adotando-se o modelo particionado. O modelo de acoplamento implementado garante ainda a utilização de malhas do fluido e da estrutura sem a necessidade de coincidência de nós. / Interaction between fluids and structures characterizes a nonlinear multi-physics problem presente in a wide range of engineering fields. This works presets the development of computational tools based on finite element method (FEM) for fluid-structure interaction (FSI) analysis considering low speed flows (incompressible), as a great part of the engineering problems. Given the topic multidisciplinary nature, it is necessary to study three different subjects: the computational structural dynamics, the computational fluid mechanics and the coupling problem. Regarding structural mechanics, we seek to employ a finite element adequate to FSI simulation, what clearly demands a geometric nonlinear analysis. We chose to employ shell elements with formulation in terms of positions, which avoids problems related to finite rotations approximations. Concerning computational fluid dynamics, we employ a stable method, at same time sensible o structural movements, which is written in the arbitrary Lagrangian-Eulerian (ALE) description. The flow incompressibility demands, for a stable method, the use of elements according to the Ladyzhenskaya-Bbuska-Brezzi (LBB) condition. It is also necessary to employ methods able to neutralize the spurious variations that appears from convection dominated flows when applying the standard Galerking method. In order to overcome this problem, we apply the Streamline-Upwind/Petrov-Galerkin (SUPG) method, which adds artificial diffusivity to the streamline direction, controlling spurious variations. Considering the fluid-shell coupling, we seek modularity and versatility, adopting the partitioned model. The developed coupling model ensure the use of fluid and structure meshes with no need for matching nodes.

Au cours de ces travaux de thèse, la résolution de problèmes non-linéaires en interaction forte entre une structure et un fluide a été étudiée par une approche partitionnée. La stabilité, la convergence et les performances de différents schémas de couplages explicites et implicites ont été explorées. L'approche partitionnée autorise la réutilisation des codes existants dans un contexte plus général. Un des objectifs de nos travaux est de les utiliser comme des boites noires, dont on n'a pas le besoin de connaitre le fonctionnement interne. A cette fin, la technologie des composants et le middleware CTL ont été utilisés. Ainsi, deux composants basés sur des codes existants pour le fluide et la structure ont été développés puis couplés par une approche de type code maître.Les performances de différentes architectures de composants aussi bien que la communication entre composants parallélisés sont décrites dans ce document. La réutilisation de codes existants permet de profiter au plus vite des modèles avancés développés de manière spécifique pour nos sous-problèmes. Pour la partie solide, par exemple, il est possible d'utiliser différents modèles éléments finis en grandes déformations avec des matériaux non-linéaires. Pour la partie fluide, nous avons choisi une approche arbitrairement Lagrangienne-Eulérienne, et la résolution par volumes finis. Différents régimes d'écoulements instationnaires aussi bien incompressibles (modélisés alors par les équations de Navier-Stokes) qu'à surfaces libres sont ici considérés. La description de phénomènes tels que le déferlement des vagues et leur impact sur des structures est ainsi rendu possible / A partitioned approach is studied to solve strongly coupled nonlinear fluid structure interaction problems. The stability, convergence and performance of explicit and implicit coupling algorithms are explored. The partitioned approach allows to re-use existing codes in a more general context. One purpose of this work is to be able to couple them as black-boxes. To that end, the scientific software component framework CTL is considered. Therefore a fluid and a structure component based on existing software are developed and coupled with a master code approach. Computational performance of different remote calls and parallel implementation of components are also depicted herein. The re-use of existing software allows to couple advanced models developed for both sub-problems. In this work, the structure part is solved by the Finite Element Method, with the possibility to use different non-linear and large deformation behaviors. For the fluid part, examples modeled with an arbitrary Lagrangian Eulerian formulation are considered, solved with a finite volume method. The models used are first transient incompressible flows described by the Navier-Stokes equation, then free surface flows. With the latter, the impact of sloshing and breaking waves on model structures can be computed / In dieser Doktorarbeit wird ein partiotionierter Ansatz zur Lösung nichlinearer stark gekoppelter Fluid-Struktur-Interaktionsprobleme behandelt. Dabei werden die Stabilität, die Konvergenz und die Performanz expliziter und impliziter Kopplungsalgorithmen untersucht. Der partitionierte Ansatz ermöglicht die Wiederverwendung von existierender Software in einem allgemeineren Kontext. Ein Ziel dieser Arbeit ist hierbei die Nutzung dieser Software als Blackboxen. Hierzu verwenden wir das komponentenbasierte Framework CTL. Die existierenden Simulationscodes für das Strömungs- und das Strukturproblem werden als CTL Komponenten umgesetzt und über einen Mastercode gekoppelt. Die Performanz des Gesamtsystems wird hinsichtlich unterschiedlicher Komponentenbindungen und der parallelen Implementierungen der Simulationskomponenten analysiert. Existierende Simulationscodes weisen mitunter viele Mannjahre Entwicklungszeit auf, bieten auf die einzelnen Probleme abgestimmte numerische Verfahren und unterstützen unterschiedliche Modelle des betrachteten physikalischen Fachgebietes. Daher ist eine Wiederverwendung erstrebenswert. Der Strukturteil wird über die Finite Elemente Methode approximiert, wobei groé Deformationen und verschiedene nicht-lineare Materialmodelle unterstützt werden. Auf der Strömungsseite werden Beispielprobleme (von instationären inkompressiblen Strömungen zu Strömungen mit freier Oberäche) herangezogen, die mit der Arbitrary Lagrangian Eulerian Methode formuliert und der Finite Volumen Methode diskretisiert werden

Disertacijos tikslai: išplėtoti biortogonalių orbitalių metodą energijų ir kitų svarbių atominių charakteristikų skaičiavimui; gauti tikslesnes atomines charakteristikas (energijos lygmenis, šuolių tikimybes, lygmenų gyvavimo trukmes) ab initio metodu. Disertacija sudaryta iš šešių skyrių. Pirmas skyrius yra įvadinis. Jame pristatomi disertacijos tikslai, uždaviniai ir ginamieji teiginiai. Antras skyrius skirtas disertacijoje naudojamiems ir kuriamiems teoriniams metodams aprašyti. Jame aprašomas naujai sukurtas PCFI artinys paremtas biortogonaliomis transformacijomis ir aprašomi, kokie pakeitimai buvo padaryti Breito ir Paulio operatorių matricinių elementų išraiškose, atsižvelgiant į biortogonalių orbitalių metodo specifiką. Kiti trys skyriai skirti disertacijoje gautiems rezultatams pristatyti. Kiekviename iš jų pateikiama mokslinių tyrimų apžvalga ir svarba. Trečiame skyriuje pateikiami apskaičiuoti spektroskopiniai duomenys boro, anglies, azoto ir deguonies izoelektronėms sekoms. Ketvirtame skyriuje pateikiami W24+ jono energijos lygmenys, stipriausi elektriniai dipoliniai šuoliai, gyvavimo trukmės. Penktame skyriuje pateikiami suskirstytų koreliacinių funkcijų sąveikos metodo taikymai ličio ir boro atomams. Neutralaus boro šuolio energijos tarp 2Po - 4P termų skaičiavimai atlikti naudojantis MCHF bei PCFI metodais. Paskutiniame skyriuje pateikiamos disertacijos išvados. / The main goals of the study are: to develop the biorthogonal orbital method for calculation of energies and other important atomic data; to obtain more accurate atomic data (energy levels, transition rates, and lifetimes) using ab initio method. The doctoral dissertation consists of six chapters. Chapter 1 introduces the main goals, main tasks of the study and statements presented for defence. Chapter 2 is designed to describe theoretical methods that were used in the thesis. There is also an account of the newly developed PCFI method based on biorthogonal transformations and the modifications in spin-angular part that were needed. The other three chapters are devoted to presenting the results obtained in the dissertation. Each of them has a scientific review of the research and importance. Also the results obtained in this work are compared with other authors’ theoretical and experimental data. Chapter 3 presents the calculation of spectroscopic data of boron, carbon, nitrogen and oxygen isoelectronic sequences. Chapter 4 presents the results of the W24+ calculations: energy spectra structure, the strongest electric dipole transitions, and the lifetimes. In Chapter 5 applications of PCFI approach are presented for lithium and boron. For neutral boron the 2Po and 4P transition energy was calculated using MCHF and PCFI methods. Chapter 6 presents the conclusions of the study.

The main goals of the study are: to develop the biorthogonal orbital method for calculation of energies and other important atomic data; to obtain more accurate atomic data (energy levels, transition rates, and lifetimes) using ab initio method. The doctoral dissertation consists of six chapters. Chapter 1 introduces the main goals, main tasks of the study and statements presented for defence. Chapter 2 is designed to describe theoretical methods that were used in the thesis. There is also an account of the newly developed PCFI method based on biorthogonal transformations and the modifications in spin-angular part that were needed. The other three chapters are devoted to presenting the results obtained in the dissertation. Each of them has a scientific review of the research and importance. Also the results obtained in this work are compared with other authors’ theoretical and experimental data. Chapter 3 presents the calculation of spectroscopic data of boron, carbon, nitrogen and oxygen isoelectronic sequences. Chapter 4 presents the results of the W(24+) calculations: energy spectra structure, the strongest electric dipole transitions, and the lifetimes. In Chapter 5 applications of PCFI approach are presented for lithium and boron. For neutral boron the 2Po and 4P transition energy was calculated using MCHF and PCFI methods. Chapter 6 presents the conclusions of the study. / Disertacijos tikslai: išplėtoti biortogonalių orbitalių metodą energijų ir kitų svarbių atominių charakteristikų skaičiavimui; gauti tikslesnes atomines charakteristikas (energijos lygmenis, šuolių tikimybes, lygmenų gyvavimo trukmes) ab initio metodu. Disertacija sudaryta iš šešių skyrių. Pirmas skyrius yra įvadinis. Jame pristatomi disertacijos tikslai, uždaviniai ir ginamieji teiginiai. Antras skyrius skirtas disertacijoje naudojamiems ir kuriamiems teoriniams metodams aprašyti. Jame aprašomas naujai sukurtas PCFI artinys paremtas biortogonaliomis transformacijomis ir aprašomi, kokie pakeitimai buvo padaryti Breito ir Paulio operatorių matricinių elementų išraiškose, atsižvelgiant į biortogonalių orbitalių metodo specifiką. Kiti trys skyriai skirti disertacijoje gautiems rezultatams pristatyti. Kiekviename iš jų pateikiama mokslinių tyrimų apžvalga ir svarba. Trečiame skyriuje pateikiami apskaičiuoti spektroskopiniai duomenys boro, anglies, azoto ir deguonies izoelektronėms sekoms. Ketvirtame skyriuje pateikiami W(24+) jono energijos lygmenys, stipriausi elektriniai dipoliniai šuoliai, gyvavimo trukmės. Penktame skyriuje pateikiami suskirstytų koreliacinių funkcijų sąveikos metodo taikymai ličio ir boro atomams. Neutralaus boro šuolio energijos tarp 2Po - 4P termų skaičiavimai atlikti naudojantis MCHF bei PCFI metodais. Paskutiniame skyriuje pateikiamos disertacijos išvados.

O presente trabalho consiste no uso do Método dos Elementos Finitos (MEF) para a análise de interação fluido-estruturas de barras com foco em problemas transientes envolvendo explosões ou outras ações com propagação de ondas de choque. Para isso é necessário o estudo de três diferentes aspectos: a dinâmica das estruturas computacional, a dinâmica dos fluidos computacional e o problema do acoplamento. No caso da dinâmica das estruturas computacional deve-se identificar em função da cinemática de deformações, quais são os requisitos para que um elemento seja adequado para analisar tais problemas, tendo em vista que a formulação deve admitir grandes deslocamentos. Para evitar problemas relacionados com aproximações de rotações finitas, opta-se por empregar uma formulação descrita em termos de posições e que leva em consideração os efeitos de empenamento da seção transversal. No caso da dinâmica dos fluidos computacional, busca-se uma formulação para escoamentos compressíveis que seja estável e ao mesmo tempo sensível ao movimento da estrutura, sendo empregado um algoritmo de integração temporal explícito baseado em características com as equações governantes descritas na forma Lagrangeana-Euleriana Arbitrária (ALE). No que se refere ao acoplamento, busca-se modularidade e versatilidade, empregando-se um modelo particionado fraco (explícito) de acoplamento e técnicas de transferência das condições de contorno (Dirichlet-Neummann), sendo estudados os efeitos de utilizar transferência bidirecional ou unidirecional dessas condições de contorno. / This work consists in the use of the Finite Element Method (FEM) for numerical analysis of fluid-bar structures, focusing on transient problems involving explosions or other actions with shock waves propagation. For this purpose, one needs to study three different aspects: the computational structural dynamics, the computational fluid dynamics and the coupling problem. Regarding computational structural dynamics, one need firstly to identify the requirements for an element to be adequate to analyze such problems, taking into account the fact that such element should admit large displacements. In order to avoid problems related to finite rotation approximations and to give a realist representation of a 3D bar structure, we chose a formulation defined in terms of positions and that considers the cross-section warping effects. Regarding computational fluid dynamics, we seek for a stable formulation for compressible flows, and at same time, sensitive to the movement of the structure, leading to an explicit time integration algorithm based on characteristics with governing equations described in the Arbitrary Lagrangian-Eulerian (ALE) form. Regarding to coupling, we chose to use a weak (explicit) partitioning coupling model in order to ensure modularity and versatility. The developed coupling scheme is bases on boundary conditions transfer techniques (Dirichlet-Neummann), and we study the effects of using bidirectional or unidirectional boundary conditions transfers.

L’objectif de ce travail porte sur le développement d’un modèle d’interaction fluide-structure adapté à la dynamique des éoliennes de grandes tailles avec des pales flexibles qui se déforment de manière significative sous l’effet de la pression exercée par le vent. Le modèle développé est basé sur une approche efficace d’IFS partitionnée pour un fluide incompressible et non visqueux en interaction avec une structure flexible soumise a des grandes transformations. Il permet de fournir une meilleure estimation de la charge aérodynamique et de la réponse dynamique associée du système (pales, mat, attachements, câbles) avec un temps de calcul raisonnable et pour des simulations sur des longues périodes. Pour la modélisation structurale, un élément fini de type solide 3D est développé pour l’étude dynamique des pales d’éolienne soumises à des grands déplacements et des grandes rotations. Une amélioration du comportement en flexion est proposée par l’introduction des degrés de liberté en rotation et l’enrichissement du champ de déplacements afin de décrire plus précisément la flexibilité des pales. Cet élément solide est apte de capter des modes de hautes fréquences qui peuvent s’avérer néfastes pour la stabilité du calcul. Deux techniques sont donc proposées pour les contrôler : la régularisation de la matrice masse et le développement des schémas d’intégration robustes de conservation et de dissipation d’énergie. Les chargements aérodynamiques sont modélisés en utilisant la Panel Method. Il s’agit d’une méthode aux frontières, relativement rapide par rapport à la CFD mais suffisamment précise pour calculer la distribution de la pression exercée sur la pale. Les modèles fluide et structure interagissent via un algorithme de couplage partitionné itératif dans lequel des considérations particulières sont prises en compte dans le contexte des grandes transformations. Dans un effort visant à instaurer un indicateur de fatigue dans la méthodologie proposée, des câbles précontraints sont introduits reliant le mat de l’éolienne au support. Une nouvelle formulation complémentaire en termes de contraintes est ainsi développée pour l’analyse dynamique des câbles 3D en comportement élasto-visco-plastique. Chaque méthode proposée a été d’abord validée sur des cas tests pertinents. Par la suite, des simulations numériques d’éoliennes avec des pales flexibles sont effectuées en vue d’affiner la compréhension de leur comportement dynamique et l’intérêt que la flexibilité des pales peut apporter à leur fonctionnement. / In this work, a numerical model of fluid-structure interaction is developed for dynamic analysis of giant wind turbines with flexible blades that can deflect significantly under wind loading. The model is based on an efficient partitioned FSI approach for incompressible and inviscid flow interacting with a flexible structure undergoing large transformations. It seeks to provide the best estimate of true design aerodynamic load and the associated dynamic response of such system (blades, tower, attachments, cables). To model the structure, we developed a 3D solid element to analyze geometrically nonlinear statics and dynamics of wind turbine blades undergoing large displacements and rotations. The 3D solid bending behavior is improved by introducing rotational degrees of freedom and enriching the approximation of displacement field in order to describe the flexibility of the blades more accurately. This solid iscapable of representing high frequencies modes which should be taken under control. Thus, we proposed a regularized form of the mass matrix and robust time-stepping schemes based on energy conservation and dissipation. Aerodynamic loads are modeled by using the 3D Vortex Panel Method. Such boundary method is relatively fast to calculate pressure distribution compared to CFD and provides enough precision. The aerodynamic and structural parts interact with each other via a partitioned coupling scheme with iterative procedure where special considerations are taken into account for large overall motion. In an effort to introduce a fatigue indicator within the proposed framework, pre-stressed cables are added to the wind turbine, connecting the tower to the support and providing more stability. Therefore, a novel complementary force-based finite element formulation is constructed for dynamic analysis of elasto-viscoplastic cables. Each of theproposed methods is first validated with differents estexamples.Then,several numerical simulations of full-scale wind turbines are performed in order to better understand its dynamic behavior and to eventually optimize its operation.