Estruturas como torres e chaminés industriais são bastante vulneráveis ao fenômeno de desprendimento de vórtices, devido à sua esbeltez e forma rombuda. Além disso, devido ao baixo amortecimento estrutural que possuem, essas estruturas também têm maiores chances de atingir grandes amplitudes de deslocamento, o que é causado pelo efeito de captura. Apesar de esse tipo de estrutura ser considerado simples dos pontos de vista estrutural e aerodinâmico, o estudo das vibrações transversais nessas estruturas é bastante complicado, pois envolve a interação entre tópicos complexos da mecânica dos fluidos e estrutural, tornando a determinação confiável da resposta estrutural um dos problemas mais difíceis da Engenharia do Vento. Ao longo das últimas cinco décadas, diversos pesquisadores vêm estudando esse fenômeno, buscando uma abordagem que consiga considerar todos os tópicos que envolvem o mecanismo de vibração por desprendimento de vórtices. Entretanto, apesar dos esforços, os modelos existentes para a verificação da resposta da estrutura são de caráter empírico, sendo os dois mais aceitos pela comunidade científica o modelo de comprimento de correlação de Ruscheweyh e o modelo matemático espectral de Vickery e Clark, o qual foi posteriormente aprimorado por Vickery e Basu. Primeiramente, são estudados em detalhe esses dois modelos e seus métodos derivados, os quais são apresentados em normas e códigos. Após isso, é feita uma proposta de cálculo de dimensionamento do deslocamento do topo de tais estruturas baseada no modelo de Vickery e Basu e adaptada às necessidades da NBR- 6123. E finalmente, são apresentados dados de 42 estruturas, as quais atingiram grandes amplitudes de vibração em seu topo. Essas estruturas foram dimensionadas segundo as diretrizes de cada um dos métodos estudados neste trabalho, o que demonstrou o bom desempenho do Método II do Eurocódigo, do Método do CICIND e da Proposta III-B para a NBR-6123. / Structures like towers and industrial chimneys are quite vulnerable to the vortex shedding phenomenon, due to their slenderness and non-aerodynamic form. Furthermore, due to their low structural damping, these structures are also more likely to reach large displacement amplitudes, which is caused by the lock-in effect. Although these structures are considered as simple from structural and aerodynamic points of view, the study of cross-wind vibrations in these structures is quite complicated, as it involves the interaction of complex topics of fluid and structural mechanics, turning a reliable determination of the structural response into one of the most complicated problems in Wind Engineering. Over the past five decades, several researchers have been studying this phenomenon, seeking an approach that could consider all topics involving the vibrating mechanism by vortex shedding. However, despite the efforts, the existing models for predicting the response of the structure are empirical, with the two most accepted by the scientific community being the Ruscheweyh’s correlation length model and the Vickery & Clark’s spectral mathematical model, which was further enhanced by Vickery & Basu. Firstly, these two models and their derivative methods, which are reported in standards and codes, are studied in detail. After, a calculation proposal for predicting the top displacement of such structures is presented, which is based on the Vickery & Basu model and adapted to the needs of NBR-6123. Finally, data for 42 real structures which have reached large vibration amplitudes at their tops is presented. These structures were designed according to the guidelines for each of the methods studied in this work, which demonstrated the good performance of the Eurocode II Method, of the CICIND Method and of the NBR-6123 III-B Proposal.

Made available in DSpace on 2014-06-11T19:34:59Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-02-06Bitstream added on 2014-06-13T21:06:54Z : No. of bitstreams: 1 sambugaro_r_dr_botfca.pdf: 1143633 bytes, checksum: 25f9ce4aa41c21b2302d4b0e2e19e340 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / The rubber tree is a tropical species that loses its leaves periodically. This deciduifolio habit is an important character for the rubber tree, that is, clones uniform defoliation provides a reduction in the pathogens inocule whose reproductive structures are located in the old leaves. After defoliation, it occurs the foliar renewal and it is at this stage, also known as refoliation, that the rubber tree presents susceptible leaflets in which occur most part of the foliar deseases, such as leaf blight, where the cycle of the pathogen (Microcyclus ulei (P. Henn.)v. Arx) is straightly related with the foliar stages (B, C and D). Therefore, the knowledge on these stages, clones phenologic behavior, factors that influence this character and local climate conditions is important for their selection. The objectives of this work were: characterize through quantitative and descriptive foliar morphology the stages B, C and D; characterize the phenologic behavior and the incidence of South American Leaf Blight; correlate the beginning of the defoliation period with climatic parameters, and leaf blight incidence, during the foliar renewal period, with climatic parameters. For the stages characterization, it was used the clone PB 235, from which the leaves central leaflets were collected, at different stages. It was measured the foliolar limbus lenght, width and area, and the petiole lenght and diameter. It was also determined the form of the limbus, apex and base of the foliolar lamina, as well the leaf coloration. For the other objectives, the clones Fx 3844, Fx 3864, Fx 2261, IAN 873, IAN 717 and RRIM 600 of rubber trees from Vale do Ribeira region, São Paulo state were used, being the fallen leaflets collected weekly in four baskets by clone, randomly distributed. The leaflets were totalized, separated by age and analyzed as for the incidence of the fungus Microcyclus ulei... (Complete abstract click electronic access below)

O conhecimento do comportamento aerodinâmico do tabuleiro de uma ponte é um fator determinante em projetos de pontes e na resolução de problemas práticos de engenharia associados. No Brasil ainda são poucas, mas crescentes, as construções de pontes com cabos, sejam elas pênseis ou estaiadas. Estas fazem parte do foco do estudo desta tese de doutorado que visa à obtenção de contribuições para ampliar a base de dados referentes aos parâmetros que influenciam o comportamento aerodinâmico de pontes. Busca-se investigar e quantificar os efeitos de interferência devidos à ação do vento em tabuleiros paralelos (próximos) de pontes, frente à resposta induzida pelo desprendimento de vórtices, gerando subsídios para a elaboração de projetos e solução de problemas da prática da Engenharia Civil. O programa experimental foi realizado nas instalações do Túnel de Vento Prof. Joaquim Blessmann da Universidade Federal do Rio Grande do Sul. Foram realizadas medidas em modelos seccionais reduzidos de um tabuleiro de ponte. Um modelo teve sua secção transversal média instrumentada com tomadas de pressão para determinação do campo de pressões. Foram obtidos campos de pressões para o modelo isolado e para distintas configurações de vizinhança (posicionamento de outro tabuleiro idêntico paralelo ao instrumentado) O outro modelo seccional foi ensaiado com o auxílio de um dispositivo que permite a simulação de dois graus de liberdade, vertical e torcional, utilizado para a determinação do comportamento dinâmico do tabuleiro frente ao desprendimento de vórtices. Nestes testes foram investigadas as condições de vizinhança, de dispositivos aerodinâmicos (nariz de vento) além da variação do nível de amortecimento em relação ao crítico, sendo a seguir realizadas medidas do campo de velocidades no entorno do modelo do tabuleiro. Os efeitos de interferência observados, a partir dos testes com modelos estáticos, variaram de acordo com cada uma das disposições geométricas estudadas. Em determinadas situações foram observados efeitos benéficos de proteção, entretanto, aumentos nos coeficientes também ocorreram. Os resultados obtidos com os modelos dinâmicos indicaram, de uma forma geral, melhora na estabilidade aerodinâmica em relação à situação com modelo isolado. Foi observada a ocorrência de mais de um pico na resposta vertical por desprendimento de vórtices o que ocasionou estudos adicionais aos inicialmente propostos. A partir da verificação da real possibilidade de ocorrência de mais de um pico na resposta, propõe-se a inclusão de novas orientações para o projeto de estruturas suscetíveis a vibrações verticais por desprendimento de vórtices em texto de normas ou recomendações de projeto. / The knowledge of the aerodynamic behavior of a bridge deck is a major factor in the design of bridges and in the solving of related engineering problems. There are still not many suspension or cable stayed bridges in Brazil, although the construction of these kind of structures has been increasing in the last years. This Thesis has the aim of contributing with the broadening of the state of the art in the aerodynamics of cable stayed bridges. The objective is to investigate the effects of aerodynamic interference in closely spaced bridge decks due to vortex shedding. The experimental program was performed in the boundary layer wind tunnel Prof. Joaquim Blessmann of the Universidade Federal do Rio Grande do Sul. The measurements were obtained through sectional models of bridge decks. One of the models was instrumented with pressure taps for the measurement of the individual pressure field (isolated model) as well as for several vicinity configurations (two closely spaced parallel models). The other sectional model was tested through an experimental device which allows the simulation of two degrees of freedom, vertical and torsional, used for the investigation of the bridge deck behavior under vortex shedding excitation. Several vicinity configurations, aerodynamic devices, damping levels and measurement points around the models were investigated in the wind tunnel tests. The interference effects observed from the static models vary according to each one of the geometric positions studied. For some situations there were beneficial protection effects, although an increase in the value of the coefficients also occurred. The results from the dynamic model have generally indicated an improvement in the aerodynamic stability in relation to the isolated model. It was also observed that more than one peak occurred for the vertical response due to vortex shedding, which lead to additional studies to the initial planned. From these observations, the inclusion of new guidelines for the design of structures susceptible to vertical vibrations due to vortex shedding, in the specific codes, are recommended.

Orientador: Edson Luiz Furtado / Banca: Nilton Luiz de Souza / Banca: Roberto Antonio Rodella / Banca: José Otavio Machado Menten / Banca: Adriana Martins / Abstract: The rubber tree is a tropical species that loses its leaves periodically. This deciduifolio habit is an important character for the rubber tree, that is, clones uniform defoliation provides a reduction in the pathogens inocule whose reproductive structures are located in the old leaves. After defoliation, it occurs the foliar renewal and it is at this stage, also known as refoliation, that the rubber tree presents susceptible leaflets in which occur most part of the foliar deseases, such as leaf blight, where the cycle of the pathogen (Microcyclus ulei (P. Henn.)v. Arx) is straightly related with the foliar stages (B, C and D). Therefore, the knowledge on these stages, clones phenologic behavior, factors that influence this character and local climate conditions is important for their selection. The objectives of this work were: characterize through quantitative and descriptive foliar morphology the stages B, C and D; characterize the phenologic behavior and the incidence of South American Leaf Blight; correlate the beginning of the defoliation period with climatic parameters, and leaf blight incidence, during the foliar renewal period, with climatic parameters. For the stages characterization, it was used the clone PB 235, from which the leaves central leaflets were collected, at different stages. It was measured the foliolar limbus lenght, width and area, and the petiole lenght and diameter. It was also determined the form of the limbus, apex and base of the foliolar lamina, as well the leaf coloration. For the other objectives, the clones Fx 3844, Fx 3864, Fx 2261, IAN 873, IAN 717 and RRIM 600 of rubber trees from Vale do Ribeira region, São Paulo state were used, being the fallen leaflets collected weekly in four baskets by clone, randomly distributed. The leaflets were totalized, separated by age and analyzed as for the incidence of the fungus Microcyclus ulei... (Complete abstract click electronic access below) / Doutor

Estruturas como torres e chaminés industriais são bastante vulneráveis ao fenômeno de desprendimento de vórtices, devido à sua esbeltez e forma rombuda. Além disso, devido ao baixo amortecimento estrutural que possuem, essas estruturas também têm maiores chances de atingir grandes amplitudes de deslocamento, o que é causado pelo efeito de captura. Apesar de esse tipo de estrutura ser considerado simples dos pontos de vista estrutural e aerodinâmico, o estudo das vibrações transversais nessas estruturas é bastante complicado, pois envolve a interação entre tópicos complexos da mecânica dos fluidos e estrutural, tornando a determinação confiável da resposta estrutural um dos problemas mais difíceis da Engenharia do Vento. Ao longo das últimas cinco décadas, diversos pesquisadores vêm estudando esse fenômeno, buscando uma abordagem que consiga considerar todos os tópicos que envolvem o mecanismo de vibração por desprendimento de vórtices. Entretanto, apesar dos esforços, os modelos existentes para a verificação da resposta da estrutura são de caráter empírico, sendo os dois mais aceitos pela comunidade científica o modelo de comprimento de correlação de Ruscheweyh e o modelo matemático espectral de Vickery e Clark, o qual foi posteriormente aprimorado por Vickery e Basu. Primeiramente, são estudados em detalhe esses dois modelos e seus métodos derivados, os quais são apresentados em normas e códigos. Após isso, é feita uma proposta de cálculo de dimensionamento do deslocamento do topo de tais estruturas baseada no modelo de Vickery e Basu e adaptada às necessidades da NBR- 6123. E finalmente, são apresentados dados de 42 estruturas, as quais atingiram grandes amplitudes de vibração em seu topo. Essas estruturas foram dimensionadas segundo as diretrizes de cada um dos métodos estudados neste trabalho, o que demonstrou o bom desempenho do Método II do Eurocódigo, do Método do CICIND e da Proposta III-B para a NBR-6123. / Structures like towers and industrial chimneys are quite vulnerable to the vortex shedding phenomenon, due to their slenderness and non-aerodynamic form. Furthermore, due to their low structural damping, these structures are also more likely to reach large displacement amplitudes, which is caused by the lock-in effect. Although these structures are considered as simple from structural and aerodynamic points of view, the study of cross-wind vibrations in these structures is quite complicated, as it involves the interaction of complex topics of fluid and structural mechanics, turning a reliable determination of the structural response into one of the most complicated problems in Wind Engineering. Over the past five decades, several researchers have been studying this phenomenon, seeking an approach that could consider all topics involving the vibrating mechanism by vortex shedding. However, despite the efforts, the existing models for predicting the response of the structure are empirical, with the two most accepted by the scientific community being the Ruscheweyh’s correlation length model and the Vickery & Clark’s spectral mathematical model, which was further enhanced by Vickery & Basu. Firstly, these two models and their derivative methods, which are reported in standards and codes, are studied in detail. After, a calculation proposal for predicting the top displacement of such structures is presented, which is based on the Vickery & Basu model and adapted to the needs of NBR-6123. Finally, data for 42 real structures which have reached large vibration amplitudes at their tops is presented. These structures were designed according to the guidelines for each of the methods studied in this work, which demonstrated the good performance of the Eurocode II Method, of the CICIND Method and of the NBR-6123 III-B Proposal.

O conhecimento do comportamento aerodinâmico do tabuleiro de uma ponte é um fator determinante em projetos de pontes e na resolução de problemas práticos de engenharia associados. No Brasil ainda são poucas, mas crescentes, as construções de pontes com cabos, sejam elas pênseis ou estaiadas. Estas fazem parte do foco do estudo desta tese de doutorado que visa à obtenção de contribuições para ampliar a base de dados referentes aos parâmetros que influenciam o comportamento aerodinâmico de pontes. Busca-se investigar e quantificar os efeitos de interferência devidos à ação do vento em tabuleiros paralelos (próximos) de pontes, frente à resposta induzida pelo desprendimento de vórtices, gerando subsídios para a elaboração de projetos e solução de problemas da prática da Engenharia Civil. O programa experimental foi realizado nas instalações do Túnel de Vento Prof. Joaquim Blessmann da Universidade Federal do Rio Grande do Sul. Foram realizadas medidas em modelos seccionais reduzidos de um tabuleiro de ponte. Um modelo teve sua secção transversal média instrumentada com tomadas de pressão para determinação do campo de pressões. Foram obtidos campos de pressões para o modelo isolado e para distintas configurações de vizinhança (posicionamento de outro tabuleiro idêntico paralelo ao instrumentado) O outro modelo seccional foi ensaiado com o auxílio de um dispositivo que permite a simulação de dois graus de liberdade, vertical e torcional, utilizado para a determinação do comportamento dinâmico do tabuleiro frente ao desprendimento de vórtices. Nestes testes foram investigadas as condições de vizinhança, de dispositivos aerodinâmicos (nariz de vento) além da variação do nível de amortecimento em relação ao crítico, sendo a seguir realizadas medidas do campo de velocidades no entorno do modelo do tabuleiro. Os efeitos de interferência observados, a partir dos testes com modelos estáticos, variaram de acordo com cada uma das disposições geométricas estudadas. Em determinadas situações foram observados efeitos benéficos de proteção, entretanto, aumentos nos coeficientes também ocorreram. Os resultados obtidos com os modelos dinâmicos indicaram, de uma forma geral, melhora na estabilidade aerodinâmica em relação à situação com modelo isolado. Foi observada a ocorrência de mais de um pico na resposta vertical por desprendimento de vórtices o que ocasionou estudos adicionais aos inicialmente propostos. A partir da verificação da real possibilidade de ocorrência de mais de um pico na resposta, propõe-se a inclusão de novas orientações para o projeto de estruturas suscetíveis a vibrações verticais por desprendimento de vórtices em texto de normas ou recomendações de projeto. / The knowledge of the aerodynamic behavior of a bridge deck is a major factor in the design of bridges and in the solving of related engineering problems. There are still not many suspension or cable stayed bridges in Brazil, although the construction of these kind of structures has been increasing in the last years. This Thesis has the aim of contributing with the broadening of the state of the art in the aerodynamics of cable stayed bridges. The objective is to investigate the effects of aerodynamic interference in closely spaced bridge decks due to vortex shedding. The experimental program was performed in the boundary layer wind tunnel Prof. Joaquim Blessmann of the Universidade Federal do Rio Grande do Sul. The measurements were obtained through sectional models of bridge decks. One of the models was instrumented with pressure taps for the measurement of the individual pressure field (isolated model) as well as for several vicinity configurations (two closely spaced parallel models). The other sectional model was tested through an experimental device which allows the simulation of two degrees of freedom, vertical and torsional, used for the investigation of the bridge deck behavior under vortex shedding excitation. Several vicinity configurations, aerodynamic devices, damping levels and measurement points around the models were investigated in the wind tunnel tests. The interference effects observed from the static models vary according to each one of the geometric positions studied. For some situations there were beneficial protection effects, although an increase in the value of the coefficients also occurred. The results from the dynamic model have generally indicated an improvement in the aerodynamic stability in relation to the isolated model. It was also observed that more than one peak occurred for the vertical response due to vortex shedding, which lead to additional studies to the initial planned. From these observations, the inclusion of new guidelines for the design of structures susceptible to vertical vibrations due to vortex shedding, in the specific codes, are recommended.

Orientador: Walmir de Freitas Filho / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-13T11:32:14Z (GMT). No. of bitstreams: 1 Trindade_FernandaCasenoLima_M.pdf: 1160331 bytes, checksum: 8645597088992da29acb335423c8dbc4 (MD5) Previous issue date: 2009 / Resumo: Sistemas industriais modernos são instalações bastante complexas com elevado grau de automatização e com capacidade de operar de forma isolada (ilhada) da rede elétrica após a ocorrência de contingências devido à utilização de geradores próprios compostos principalmente por máquinas síncronas e turbinas térmicas. Tais instalações, na presença de geradores, são denominadas genericamente como consumidores autoprodutores. Como muitos desses autoprodutores são conectados em redes de distribuição e subtransmissão de energia elétrica, tais consumidores estão sujeitos às normas técnicas requeridas por essas concessionárias. Assim, a desconexão da instalação industrial logo após a ocorrência de um ilhamento na rede de distribuição é um procedimento obrigatório. Imediatamente após a detecção do ilhamento pelo sistema de proteção da instalação industrial, a rede de distribuição e o sistema industrial são separados (isolados). Esta separação é realizada através da abertura do disjuntor instalado no lado de baixa tensão do transformador (lado do consumidor) que faz a conexão entre os dois sistemas. Então, a concessionária pode realizar os procedimentos necessários para reenergização da rede. Logo após a realização da separação dos sistemas, é necessário adotar uma série de medidas que garanta que o sistema industrial possa continuar operando isoladamente de forma adequada. Basicamente, três ações devem ser tomadas: (a) mudança do modo de operação do regulador de velocidade e do sistema de excitação dos geradores síncronos; (b) implementação do sistema de rejeição de carga e (c) alteração dos ajustes dos relés de sobrecorrente do sistema de proteção da rede industrial. Nesse contexto, o objetivo desta dissertação de mestrado é investigar tais procedimentos e propor metodologias de análise dessas questões previamente mencionadas de forma a obter um melhor entendimento do problema. Com o desenvolvimento dessas metodologias, objetiva-se que os estudos desses procedimentos automáticos possam ser realizados de forma mais eficiente e sistemática. / Abstract: Modern industrial systems are very sophisticated installations with a high number of automatic processes and capability of isolated (islanded) operation after contingences by using onsite generators composed mainly by synchronous machines and steam turbines. Such installations, in the presence of generators, are generically called autoproducers. Since many of these autoproducers are connected to electrical power distribution and subtransmission grids, they must respect the technical recommendations imposed by these utilities. As a consequence, the disconnection of these systems from the grid after islanding occurrence is a mandatory procedure. Soon after the islanding detection by the industrial protection system, the industry and the grid must be electrically separated (isolated) by opening the circuit breaker installed at the low voltage side of the interconnection transformer. Thus, after the separation, the utility can carry out the necessary technical procedures to restore the network. From the industrial system perspective, after the separation, it is necessary to take control actions to guarantee that the industrial system continues operating with quality and reliability. Basically, three actions must be taken: (a) change the operation mode of the speed governor and excitation system of the generators; (b) implement the load shedding system and (c) change the settings of the protection system overcurrent relays. In this context, the objective of this master thesis is to investigate these procedures and propose methods for analysis in order to obtain a better understanding of these issues. With this methodologies development, it is expected that new automatic proceedings can be achieved in a more efficient and systematic way. / Mestrado / Energia Eletrica / Mestre em Engenharia Elétrica

The increasing nationwide interest in intelligent transportation systems (ITS) and the need for more efficient transportation have led to the expanding use of variable message sign (VMS) technology. VMS panels are substantially heavier than flat panel aluminum signs and have a larger depth (dimension parallel to the direction of traffic). The additional weight and depth can have a significant effect on the aerodynamic forces and inertial loads transmitted to the support structure. The wind induced drag forces and the response of VMS structures is not well understood. Minimum design requirements for VMS structures are contained in the American Association of State Highway Transportation Officials Standard Specification for Structural Support for Highway Signs, Luminaires, and Traffic Signals (AASHTO Specification). However the Specification does not take into account the prismatic geometry of VMS and the complex interaction of the applied aerodynamic forces to the support structure. In view of the lack of code guidance and the limited number research performed so far, targeted experimentation and large scale testing was conducted at the Florida International University (FIU) Wall of Wind (WOW) to provide reliable drag coefficients and investigate the aerodynamic instability of VMS. A comprehensive range of VMS geometries was tested in turbulence representative of the high frequency end of the spectrum in a simulated suburban atmospheric boundary layer. The mean normal, lateral and vertical lift force coefficients, in addition to the twisting moment coefficient and eccentricity ratio, were determined using the measured data for each model. Wind tunnel testing confirmed that drag on a prismatic VMS is smaller than the 1.7 suggested value in the current AASHTO Specification (2013). An alternative to the AASHTO Specification code value is presented in the form of a design matrix. Testing and analysis also indicated that vortex shedding oscillations and galloping instability could be significant for VMS signs with a large depth ratio attached to a structure with a low natural frequency. The effect of corner modification was investigated by testing models with chamfered and rounded corners. Results demonstrated an additional decrease in the drag coefficient but a possible Reynolds number dependency for the rounded corner configuration.

L’analyse de flux de données est utilisée dans beaucoup de contexte où la masse des données et/ou le débit auquel elles sont générées, excluent d’autres approches (par exemple le traitement par lots). Le modèle flux fourni des solutions aléatoires et/ou fondées sur des approximations pour calculer des fonctions d’intérêt sur des flux (repartis) de n-uplets, en considérant le pire cas, et en essayant de minimiser l’utilisation des ressources. En particulier, nous nous intéressons à deux problèmes classiques : l’estimation de fréquence et les poids lourds. Un champ d’application moins courant est le traitement de flux qui est d’une certaine façon un champ complémentaire aux modèle flux. Celui-ci fournis des systèmes pour effectuer des calculs génériques sur les flux en temps réel souple, qui passent à l’échèle. Cette dualité nous permet d’appliquer des solutions du modèle flux pour optimiser des systèmes de traitement de flux. Dans cette thèse, nous proposons un nouvel algorithme pour la détection d’éléments surabondants dans des flux repartis, ainsi que deux extensions d’un algorithme classique pour l’estimation des fréquences des items. Nous nous intéressons également à deux problèmes : construire un partitionnement équitable de l’univers des n-uplets par rapport à leurs poids et l’estimation des valeurs de ces n-uplets. Nous utilisons ces algorithmes pour équilibrer et/ou délester la charge dans les systèmes de traitement de flux. / Nowadays stream analysis is used in many context where the amount of data and/or the rate at which it is generated rules out other approaches (e.g., batch processing). The data streaming model provides randomized and/or approximated solutions to compute specific functions over (distributed) stream(s) of data-items in worst case scenarios, while striving for small resources usage. In particular, we look into two classical and related data streaming problems: frequency estimation and (distributed) heavy hitters. A less common field of application is stream processing which is somehow complementary and more practical, providing efficient and highly scalable frameworks to perform soft real-time generic computation on streams, relying on cloud computing. This duality allows us to apply data streaming solutions to optimize stream processing systems. In this thesis, we provide a novel algorithm to track heavy hitters in distributed streams and two extensions of a well-known algorithm to estimate the frequencies of data items. We also tackle two related problems and their solution: provide even partitioning of the item universe based on their weights and provide an estimation of the values carried by the items of the stream. We then apply these results to both network monitoring and stream processing. In particular, we leverage these solutions to perform load shedding as well as to load balance parallelized operators in stream processing systems.

Les buts principaux recherchés de la présente thèse visent au développement et à l’expertise d’une méthodologie de simulation numérique des problèmes d’interactions fluides-structures. Afin de cerner progressivement le problème étudié, nous nous sommes intéressés en premier lieu à la simulation numérique des écoulements autour d’obstacles solides, plus particulièrement au phénomène d’éclatements tourbillonnaires dans la zone de sillage d’obstacles de différentes formes. Nous avons utilisé la méthode des éléments finis en adoptant la technique de stabilisation GLS (Galerkin Least-Square). Pour le traitement de la turbulence, nous avons opté pour la méthode LES (Large-Eddy Simulation) en utilisant le filtre de Smagorinsky. En deuxième phase, nous nous sommes intéressés aux écoulements en milieux déformables. Nous avons entrepris la formulation ALE (Arbitrairement Lagrangienne Eulérienne) en considérant un maillage déformable. Pour la mise à jour de la grille du maillage dynamique, nous avons utilisé une approche pseudo-élastique. Afin d’expertiser la méthodologie mise en oeuvre, nous avons choisi d’aborder le problème des ballottements à la surface libre de réservoirs partiellement remplis de liquide. En dernière partie, nous nous sommes intéressés au comportement vibratoire d’un corps solide sous l’effet d’un écoulement de fluide. Par l’utilisation d’un algorithme de couplage totalement implicite basé sur la méthode de Gauss-Seidel par Bloc, nous avons abordé le phénomène des instabilités aéroélastiques des ponts à haubans. Pour la validation du modèle numérique traitant les interactions fluides-structures par les données expérimentales, nous nous sommes intéressés au comportement vibratoire d’une maquette sectionnelle d’un tablier de pont réel sous l’effet d’un vent soufflant uniforme. / The main goals sought by this thesis target the development and expertise of a methodology for numerical simulation of fluid-structure interactions problems. In order to identify the studied problem progressively, we are interested primarily in numerical simulation of flows around bluff bodies, especially the phenomenon of vortex shedding in the wake zone of a bluff body of different shapes. We used the finite element method by adopting the stabilized GLS (Galerkin Least-Square) technique. For the treatment of turbulence, we opted the LES (Large-Eddy Simulation) method using the Smagorinsky filter. In the second phase, we were interested in flows in deformable media. We undertook the ALE (Arbitrary Lagrangian Eulerian) formulation by considering a deformable mesh. To update the grid of the dynamic mesh, we used a pseudo-elastic approach. To appraise the implemented methodology, we decided to approach the problem of sloshing at the free surface of a tank partially filled with liquid. In the final part, we were interested in vibration behavior of a solid body under the effect of fluid flow. By using a fully implicit coupling algorithm based on a relaxed Bloc Gauss-Seidel method, we studied the phenomenon of aeroelastic instability of cable-stayed bridges. To validate the numerical model treating fluid-structure interactions by experimental data, we investigated the vibration behavior of a real deck sectional model under the effect of a uniform wind.