Submitted by Maicon Juliano Schmidt (maicons) on 2015-06-30T17:56:45Z No. of bitstreams: 1 Vanessa Schweitzer dos Santos.pdf: 1081901 bytes, checksum: 117ce960501c8c561bd7ee102cf9254a (MD5) / Made available in DSpace on 2015-06-30T17:56:45Z (GMT). No. of bitstreams: 1 Vanessa Schweitzer dos Santos.pdf: 1081901 bytes, checksum: 117ce960501c8c561bd7ee102cf9254a (MD5) Previous issue date: 2013-01-31 / CNPQ – Conselho Nacional de Desenvolvimento Científico e Tecnológico / FINEP - Financiadora de Estudos e Projetos / Ministério da Ciência e Tecnologia / O lixiviado de aterro sanitário é um efluente gerado através da infiltração de águas pluviais nas camadas de cobertura do aterro e da biodegradação da fração orgânica dos resíduos sólidos urbanos aterrados. Caracteriza-se por um alto potencial poluidor e elevadas concentrações de matéria orgânica, portanto sua coleta e tratamento posterior são necessários. Sistemas biológicos podem ser aplicados no seu tratamento, visando remover matéria orgânica e nutrientes através das atividades metabólicas dos micro-organismos envolvidos no processo. Os contactores biológicos rotatórios são reatores cilíndricos que possuem em seu interior meios de suporte, onde a biomassa atua fixada, na forma de biofilme. Este entra em contato com o substrato através de rotação mecânica do tambor cilíndrico no efluente. Esta pesquisa teve como objetivo principal estudar a capacidade de remoção de matéria orgânica de lixiviado de aterro sanitário, através da utilização de um contactor biológico rotatório. O lixiviado do aterro sanitário de São Leopoldo/RS foi tratado por um contactor biológico rotatório de três estágios, que foi operado de duas formas. Uma deles foi com vazão de 8,5 L/h e tempo de retenção hidráulica de 15 h (Fase 1). Neste modo de operação a carga orgânica afluente média foi de 434 mg/L de DBO (limites entre 304 mg/L e 576 mg/L), 2484 mg/L de DQO (limites entre 882 mg/L e 3617 mg/L) e 992 mg/L de COT (limites entre 405 mg/L e 1420 mg/L). O outro modo de operação testado teve vazão de 5,1 L/h e tempo de retenção hidráulica de 24 h (Fase 2). A carga orgânica afluente média foi de 500 mg/L de DBO (limites entre 325 mg/L e 580 mg/L), 3818 mg/L de DQO (limites entre 2647 mg/L e 4764 mg/L) e 1250 mg/L de COT (limites entre 940 mg/L e 1360 mg/L). O lixiviado pesquisado apresentou como principal característica a baixa biodegradabilidade, além de ampla variação em sua composição ao longo do experimento, principalmente na Fase 1. Esta variação em sua composição pode ter afetado as eficiências de remoção de matéria orgânica, que foram de 50% de DBO, 11% de DQO e 13% de COT na Fase 1. Na Fase 2 os valores afluentes se mantiveram mais semelhantes, e as taxas de remoção de matéria orgânica foram mais constantes, além de que os valores médios de eficiência de remoção foram maiores do que os verificados na Fase 1. As eficiências de remoção na Fase 2 foram de 66% de DBO, 15% de DQO e 18% de COT. O aumento do tempo de retenção hidráulica na Fase 2 resultou em aumento da eficiência de remoção de matéria orgânica. Este efeito provavelmente está associado ao maior tempo de contato entre a biomassa e o substrato disponível no lixiviado de aterro sanitário. Quanto à remoção de matéria orgânica nos diferentes estágios do contactor biológico rotatório, foi observada uma maior eficiência nos dois primeiros estágios do sistema, principalmente dos parâmetros de DQO e COT, em ambas as fases monitoradas. Para o lixiviado e os modos de operação testados, o estágio 3 não apresentou eficiência que justifique sua presença, quanto aos parâmetros de DQO e COT. / The sanitary landfill leachate is an effluent generated by infiltration of rainwater into the layers of the landfill cover and biodegradation of the organic fraction of municipal solid waste grounded. It is characterized by a high pollution potential and high concentrations of organic matter, so their collection and further treatment is needed. Biological systems can be applied in their treatment in order to remove organic matter and nutrients through the metabolic activity of micro-organisms involved in the process. The rotating biological contactors are cylindrical reactors having inside support means, which acts fixed biomass in the form of biofilm. This comes into contact with the substrate by mechanical rotation of the cylindrical drum in the effluent. This research aimed to study the capacity of organic matter removal of landfill leachate, through the use of a rotating biological contactors. The landfill leachate São Leopoldo/RS was treated by a three-stage rotating biological contactor, which was operated in two modes. One was a flow rate of 8.5 L/h hydraulic retention time of 15 h (Phase 1). In this mode of operation the load influent organic average was 434 mg/L of BOD (limits between 304 mg/L and 576 mg/L), 2484 mg/L COD (limits between 882 mg/L and 3617 mg/L) and 992 mg/L of TOC (limits between 405 mg/L and 1420 mg/L). The other operation mode tested had a flow rate of 5.1 L/h and hydraulic retention time of 24 h (Phase 2). The average influent organic load was 500 mg/L of BOD (limits between 325 mg/L and 580 mg/L), 3818 mg/L COD (limits between 2647 mg/L and 4764 mg/L) and 1250 mg/L TOC (limits between 940 mg/L and 1360 mg/L). The researched showed landfill leachate as main characteristic the low biodegradability, and wide variation in composition throughout the experiment, especially in Phase 1. This variation in composition may have affected the removal efficiency of organic matter, which were 50% BOD, 11% COD and 13% TOC in Phase 1. In Phase 2 affluent values remained more similar, and the removal rates of organic matter were more constant, and that the average values of removal efficiency was higher than those observed in Phase 1. The removal efficiencies in Phase 2 were 66% BOD, 15% COD and 18% TOC. The increase in Phase 2 hydraulic retention time resulted in increased efficiency of removal of organic material. This effect is probably associated with greater contact time between the substrate and the biomass available in the landfill leachate. As for the removal of organic matter at different stages of rotating biological contactor, greater efficiency was observed in the first two stages of the system, particularly the parameters of COD and TOC in both phases monitored. For leachate and operating modes tested, stage 3 showed no efficiency to justify their presence, for the parameters COD and TOC.

Submitted by William Justo Figueiro (williamjf) on 2015-07-14T23:05:27Z No. of bitstreams: 1 03c.pdf: 7786125 bytes, checksum: 1e0da23c7cb679804d62aea58a41732a (MD5) / Made available in DSpace on 2015-07-14T23:05:27Z (GMT). No. of bitstreams: 1 03c.pdf: 7786125 bytes, checksum: 1e0da23c7cb679804d62aea58a41732a (MD5) Previous issue date: 2013-04-30 / CNPQ – Conselho Nacional de Desenvolvimento Científico e Tecnológico / FINEP - Financiadora de Estudos e Projetos / O lixiviado gerado nos aterros caracteriza-se por conter altos teores de material orgânico recalcitrante e nutrientes com alto potencial poluidor. Diversas alternativas para o tratamento de lixiviados de aterros sanitários (LAS) têm sido amplamente estudadas obtendo-se bons resultados quanto à remoção de matéria orgânica biodegradável, porém, em sua maioria, não atingem os padrões de lançamento quanto à remoção de nutrientes. Tendo em vista a promoção de um tratamento adequado aos lixiviados e a minimização de impactos ambientais causados por este efluente, este trabalho estudou a aplicação de um contactor biológico rotatório (CBR) de 3 estágios, em escala piloto, para o tratamento de LAS. O objetivo deste trabalho foi avaliar o desempenho do CBR quanto à remoção de nitrogênio e verificar a relação desta com outros parâmetros como o TRH, razão C/N, cargas superficiais aplicadas e remoção dos compostos orgânicos. O sistema experimental foi operado com alimentação continua de lixiviado proveniente do aterro sanitário de São Leopoldo. Não foram realizados ajustes de pH e temperatura. Nas primeiras 8 semanas operou-se o sistema com um TRH de 15 h (fase 1) e nas 8 semanas subsequentes com TRH de 24h (fase 2). Como resultado, observou-se que a oxidação do nitrogênio amoniacal (NA) alcançou 94% na fase 2 de operação sendo este valor significativamente maior do que o da fase 1 onde se obteve cerca de 49% de oxidação do NA. Não foram obtidas boas remoções de orgânicos, porem observou-se uma melhora na remoção de todos os parâmetros na fase 2 de operação. Esta melhora na eficiência do sistema na fase 2 foi atribuída ao aumento de TRH. Quanto à avaliação da nitrificação no sistema, foi possível observar, na fase 2 de operação, o acúmulo de nitrito predominantemente, enquanto a concentração de nitrato no efluente final foi praticamente inexistente variando de 13 a 31 mg/L . Para as condições avaliadas por este estudo, concluiu-se que, o CBR estudado apresenta potencial para realizar a nitrificação e remoção dos compostos nitrogenados presentes no LAS. Entretanto as condições operacionais devem ser reestudadas para permitir a nitrificação total e não apenas a formação de nitrito. Da mesma forma, prover a remoção de compostos orgânicos carbonáceos. O TRH de 24h proporcionou uma melhora nas eficiências de remoção pelo sistema. Porém, para um melhor desempenho do CBR são necessárias investigações quanto aos ajustes nos parâmetros de operação que possibilitem aumentar a eficiência tanto da nitrificação quanto na remoção de matéria orgânica carbonacea. / The leachate generated in landfills is characterized by high levels of recalcitrant organic compounds and nutrients with high polluter potential. Several alternatives for the treatment of landfill leachate (LL) have been widely studied and presented good results regarding the removal of biodegradable organic matter, however, most of these systems do not reach the standards of environmental disposal of nutrients such as nitrogen compounds. Owing to promote an appropriate treatment to the leachate and minimize the environmental impacts caused by this effluent, this work studied the application of a 3 stage rotating biological contactor (RBC) in a pilot scale. The objective of this study was to evaluate the removal of nitrogen and overall performance of the RBC and check the relationship of this removal with other parameters such as the HRT, C/N ratio, ammonium and COD loads and removal of organic compounds. The experimental system was fed continuously with leachate from São Leopoldo landfill. No adjustments of pH and temperature were made. The first 8 weeks the system was operated applying an HRT of 15 h (1st period) and for the 8 subsequent weeks with HRT of 24h (2nd period). As a result, it was observed that the oxidation of ammonium nitrogen reached 94% in the 2nd period of operation which was greater than the 1st period which obtained approximately 49% of ammonium nitrogen oxidation. Low levels of organic compounds removal were obtained, however an improvement was observed in the organics removal efficiency in the 2nd period of operation. This improvement in overall efficiency of the system in the 2nd period was due to the increase of the HRT. Regarding the evaluation of nitrification in the system, in 2nd period of operation was observed the accumulation of nitrite in the system, while the concentration of nitrate in the final effluent was practically non-existent, ranging from 13 to 31 mg/L. For the conditions evaluated in this study, the conclusion was that the experimental RBC has the potential to carry out the nitrification and the removal of nitrogen compounds in the landfill leachate. Meanwhile, the operational conditions must be re-studied to allow the total nitrification and not only the formation of nitrite, as well as provide the removal of carbonaceous organic compounds. The HRT of 24h provided an improvement on removal efficiencies by the system. However, for a better performance of the RBC, investigations are necessary concerning adjustments in the operational parameters that increase efficiency of nitrification and removal of organic matter.

De nos jours les algorithmes de vision par ordinateur abondent dans les applications de vidéo-surveillance, de reconstruction 3D, de véhicules autonomes, d'imagerie médicale, etc… La détection et la mise en correspondance d'objets dans les images constitue une étape clé dans ces algorithmes.Les méthodes les plus communes pour la mise en correspondance d'objets ou d'images sont basées sur des descripteurs locaux, avec tout d'abord la détection de points d'intérêt, puis l'extraction de caractéristiques de voisinages des points d'intérêt, et enfin la construction des descripteurs d'image.Dans cette thèse, nous présentons des contributions au domaine de la mise en correspondance d'images par l'utilisation de demi filtres tournants. Nous suivons ici trois approches : la première présente un nouveau descripteur à faible débit et une stratégie de mise en correspondance intégrés à une plateforme vidéo. Deuxièmement, nous construisons un nouveau descripteur local en intégrant la réponse de demi filtres tournant dans un histogramme de gradient orienté (HOG) ; enfin nous proposons une nouvelle approche pour la construction d'un descripteur utilisant des statistiques du second ordre. Toutes ces trois approches apportent des résultats intéressants et prometteurs.Mots-clés : Demi filtres tournants, descripteur local d'image, mise en correspondance, histogramme de gradient orienté (HOG), Différence de gaussiennes. / Nowadays computer vision algorithms can be found abundantly in applications relatedto video surveillance, 3D reconstruction, autonomous vehicles, medical imaging etc. Image/object matching and detection forms an integral step in many of these algorithms.The most common methods for Image/object matching and detection are based on localimage descriptors, where interest points in the image are initially detected, followed byextracting the image features from the neighbourhood of the interest point and finally,constructing the image descriptor. In this thesis, contributions to the field of the imagefeature matching using rotating half filters are presented. Here we follow three approaches:first, by presenting a new low bit-rate descriptor and a cascade matching strategy whichare integrated on a video platform. Secondly, we construct a new local image patch descriptorby embedding the response of rotating half filters in the Histogram of Orientedgradient (HoG) framework and finally by proposing a new approach for descriptor constructionby using second order image statistics. All the three approaches provides aninteresting and promising results by outperforming the state of art descriptors.Key-words: Rotating half filters, local image descriptor, image matching, Histogram of Orientated Gradients (HoG), Difference of Gaussian (DoG).

Resumo: Este trabalho apresenta o desenvolvimento de uma análise teórica do desempenho de um sistema de controle ativo utilizando mancais magnéticos como atuadores de não-contato para a redução de vibrações em rotores. São analisados três modelos de rotores, sendo que em um deles aplica-se apenas o controle feedback e os outros são suportados apenas por mancais magnéticos, os quais também são os atuadores do controlador. Assim, Luna arquitetura de controle tipo feedforward é empregada sobreposta ao sistema de controle feedback dos atuadores nestes dois modelos, sendo urna análise realizada em relação ao desempenho do sistema de controle quanto às diferentes geometrias de distribuição de massa acopladas ao eixo do rotor. O enfoque principal deste trabalho é voltado para a análise do desempenho do sistema de controle em função da posição e quantidade dos sensores de erro (onde se deseja minimizar as vibrações) em relação à posição dos atuadores e das forças de excitação. As excitações são do tipo síncronas e sub-síncronas que normalmente aparecem em rotores com elevadas velocidades de rotação, como as turbomáquinas. Também é realizada urna análise das forças de controle necessárias a serem aplicadas pelos atuadores para se obter urna redução dos níveis de vibração do rotor na posição dos sensores de erro do sistema feedforward. A análise é executada empregando modelos de rotores desenvolvidos pelo método da matriz de impedância. Esta pesquisa também apresenta Luna aplicação da técnica de controle Feedforward em acústica, que realiza a depuração da voz para comunicação em ambientes ruidosos. / Abstract: This research work brings a theoretical analysis of a control system performance that uses magnetic bearings as non-contact actuators to reduce rotor vibrations. It is analyzed three rotor models, in which one of them operates under the feedback control only. The other models are supported by magnetic bearings only, which also are the controller system actuators. Thus, a feedforward control scheme is applied over the feedback control inherent to the AMB control circuit. The analysis is carried out over these two last models regarding to the control performance for different geometry of mass distribution along the rotor. The focus of this work is to analyze the controller performance according to the sensor quantity and placement (where the vibrations are desired to be minimized) regarding to the actuator position and to the exciting forces. The subsynchronous and synchronous excitations are considered here since they frequently occur in high rotating speed rotors, as in the turbomachinery scenario. Also, the control force required by the actuators is monitored according to the sensors placement to reduce the local vibrations level and the analysis was carried out using the impedance matrix rotor modeling. Further, this work brings a modeling and an application of the feedforward active control scheme in the acoustics field used for voice extraction for communication in noisy environments. / Orientador: Luiz de Paula do Nascimento / Coorientador: Vicente Lopes Junior / Banca: Gilberto Pechoto de Melo / Banca: Kátia Luchese Cavalca Dedini / Mestre

Este trabalho trata de um estudo experimental das respostas de desgaste e de atrito encontradas em um sistema deslizante lubrificado. Para tanto, foram realizados ensaios de deslizamento em um equipamento para ensaios de desgaste, adotando-se o dispositivo pino-contra-disco, para ensaios com movimento relativo rotativo contínuo entre as amostras, e o dispositivo pino-contra-placa, para ensaios com movimento relativo alternado, ou oscilatório, entre as amostras. Os materiais metálicos ensaiados foram pinos de aço AISI 52100 e contra-corpos de aço AISI 8640. O óleo lubrificante foi o mineral de base parafínico, IV 100. Foram variadas as condições de aditivação e de contaminação do óleo lubrificante e foram utilizados dois níveis de carregamento mecânico, determinada pela relação velocidade/carga. O desgaste foi estudado por microscopia óptica e eletrônica de varredura, medição da área afetada pelo desgaste, perfilometria das superfícies desgastadas e análise de óleo. O atrito e o potencial de contato foram monitorados ao longo dos ensaios. Os resultados obtidos mostraram que o desgaste dos corpos metálicos foi sensível ao carregamento mecânico, à aditivação e à contaminação do óleo. Diferenças foram notadas nas morfologias superficiais entre os resultados de desgaste dos ensaios rotativos e oscilatórios. / This work concerns with experimental study of wear and friction responses of lubricated sliding system. Sliding tests were carried out using pin-on-disk wear testing machine for tests with continuous rotating movement, and the pin-on-plate device, for reciprocating tests between specimens. The metallic test coupons were AISI 52100 steel pins and AISI 8640 steel counter-faces. The used lubricant was paraffinic mineral oil, VI 100. The presence of additives and contamination in the lubricant oil were investigated under two mechanical loading levels, determined by the velocity/load relation. The wear was studied by means of optic and scanning electronic microscopes, perfilometry and dimensional analysis of the worn surfaces and oil analysis. The friction and the contact potential were monitored through out the sliding tests. The results showed that the wear of the metallic materials was susceptible to the mechanical loading, the additive and the contamination existence in the oil. It was observed differences among the wear results of the rotating and the reciprocating tests in terms of surface morphologies.

Researches from different fields around the world are searching for both new sources of biomaterials and potential hepatocytes in order to supply drug tests, cell therapies, and cell transplantation as alternative therapeutic support to liver diseases and injuries. Placenta may be eligible as a new model in tissue engineering due to its rich extracellular matrix (ECM) and availability after birth. Placental scaffolds were produced by decellularization with 0.01, 0.1 and 1% SDS, and 1% Triton X-100 which were valued by means of structure and composition. Afterwards, placental scaffolds were co-cultured with mouse embryonic fibroblasts in a tridimensional (3D) rotating system. Placental scaffolds presented a well-preserved acellular ECM containing 9.42 ± 5.2 ng dsDNA per mg of ECM. Weak collagen I of the natives clearly appears in decellularized ECM while the collagen III, once well observed in native placenta, it was absent on scaffolds. This interesting observation may have been due to the solubilization SDS-induced of the collagen III fibrils during decellularization. Fibronectin was well-observed in placental scaffolds whereas laminin and collagen IV were strongly stained. Recellularized with fibroblasts by a 3D culture system, placental scaffolds showed potential for repopulation, with cells adhered throughout its acellular ECM. Placental scaffolds were then newly recellularized, aiming now for differentiation of mouse embryonic stem cells into hepatic cells. In a protocol of 23 days, it was simulated major events of liver embryonic development by adding growth factors. As result, a high index of cells adhered, proliferated and migrated throughout outer and inner scaffolds ECM surface. Absence of Oct4 and Nanog showed that Activin A and Wnt3a (d0-6) induced primitive endoderm fate, and negative label for Foxa2 and Sox17 representing BMP4 and FGF2 (d6-10) differentiation-induced generating definitive endoderm cells. Also, FGF1, FGF4 and FG8b (d10-14) induced hepatoblast phenotype cells, that were observed positive for AFP and CK7 markers. Finally, HGF and FS-288 (d14-23) induced to hepatocyte-like cells, positive for CK18 and Alb markers. The hepatocyte-like cells functional aspects were observed by glycogen storage. Though a heterogeneous cell hepatic lineage was confirmed, mouse placental scaffolds shown a useful model to support recellularization with simultaneous differentiation into hepatic fate simulating phases of embryonic development. / Pesquisas de diferentes campos ao redor do Mundo estão em busca de novas fontes tanto de biomateriais, quanto de potenciais hepatócitos, a fim de suprir testes de drogas, terapias celulares e transplante de células, como suporte terapêutico alternativo para doenças e lesões hepáticas. Placentas podem ser elegíveis como um novo modelo em Engenharia Tecidual em decorrência de sua rica matriz extracelular (ECM), e disponibilidade após o nascimento. Os scaffolds placentários foram produzidos por decelularização com SDS 0,01, 0,1 e 1% e Triton X-100 1%, os quais foram avaliados por meio da estrutura e composição. Posteriormente, os scaffolds placentários foram co-cultivados com fibroblastos embrionários de camundongos em um sistema rotativo tridimensional (3D). Os scaffolds placentários apresentaram uma MEC acelular bem conservada, contendo 9,42 ± 5,2 ng/dsDNA/mg/MEC. O fraco colágeno I nos nativos aparece claramente na MEC descelularizada, enquanto o colágeno III bem visível na placenta nativa estava ausente nos scaffolds. Esta observação interessante pode decorrido da solubilização das fibrilas de colágeno III, induzida pelo SDS durante a decelularização. A fibronectina foi bem observada nos scaffolds placentários, enquanto a laminina e o colágeno IV estiveram fortemente marcados. Recelularizados com fibroblastos por um sistema de cultura 3D, os scaffolds placentários mostraram potencial para repovoamento, com células aderidas ao longo de sua MEC acelular. Os scaffolds placentários foram então novamente recelularizados, visando agora a diferenciação de células tronco-embrionárias de camundongos em células hepáticas. Em um protocolo de 23 dias, foram simulados os grandes eventos do desenvolvimento embrionário do fígado, pela adição de fatores de crescimento. Como resultado, um alto índice de células aderiu, proliferou e migrou através das superfícies externa e interna dos scaffolds. A ausência de Oct4 e Nanog demostraram que o Activin A e o Wnt3a (d0-6) induziram o destino endoderma primitivo, e a marcação negativa para Foxa2 e Sox17 representaram a geração de células endodermais definitivas pela diferenciação induzida por BMP4 e FGF2 (d6-10). Ainda, FGF1, FGF4 e FG8b (d10-14) induziram células do fenótipo hepatoblasto, que foram observadas positivas para os marcadores AFP e CK7. Finalmente, HGF e FS-288 (d14-23) induziram as células hepatocyte-like, positivas para os marcadores CK18 e Alb. The hepatocyte-like cells functional aspects were observed by glycogen storage. Though a heterogeneous cell hepatic lineage was confirmed, mouse placental scaffolds shown a useful model to support recellularization with simultaneous differentiation into hepatic fate simulating phases of embryonic development. Os aspectos funcionais das células hepatocyte-like foi observada pelo armazenamento de glicogênio. Embora uma linhagem hepática formada por células heterogêneas tenha sido confirmada, os scaffolds placentários de camundongos se mostraram um modelo útil para sustentar a recelularização com simultânea diferenciação em destino hepático, simulando fases do desenvolvimento embrionário.

La convection thermique dans les objets naturels de grande taille est associée à de fortes variations de la pression, hydrostatique au premier ordre. C’est le cas pour l’atmosphère de la Terre (et d’autres planètes), les planètes gazeuses géantes, les étoiles, mais aussi l’intérieur des planètes telluriques. De part l’importance des effets de compressibilité, l’approximation de Boussinesq n’y est pas vérifiée et d’autres modèles, comportant également des approximations, sont utilisés : les modèles anélastiques. Toutefois, peu d’expériences ont été réalisées pour les vérifier. Cette thèse présente une expérience dont les paramètres ont été optimisés afin d’obtenir des effets de compressibilité importants en laboratoire. Pour ce faire, une gravité apparente forte est obtenue à l’aide d’une centrifugeuse et du xénon gazeux est utilisé, nous permettant d’atteindre un nombre de dissipation significatif. Ces expériences ont permis l’observation en laboratoire d’un gradient adiabatique de 3 K/cm et d’un exposant de 0,3 pour la loi de puissance caractérisant le transfert thermique turbulent entre le nombre de Nusselt et le nombre de Rayleigh superadiabatique.L’étude des fluctuations de pression et de température montrant que l’écoulement est quasi-geostrophique dû à la forte rotation imposée par la centrifugeuse, un modèle anélastique quasi-géostrophique est développé afin de réaliser des simulations numériques bidimensionnelles relatives à l’expérience. / In large natural objects, thermal convection is associated with large pressure differences, mainly due to hydrostatic balance. This is true in the atmosphere of the Earth (and other planets), in gas giant planets, in stars, but also in the interior of telluric planets. Boussinesq approximation is not valid owing to large compressibility effects, and other approximate models can be used to model these objects, like the anelastic approximation. However, very few experiments have been performed to assess these models. In the present PhD thesis, an experiment is shown, with parameters designed to maximize compressibility effects in a laboratory. In this perspective, an enhanced apparent gravity is obtained using a centrifuge, and Xenon gas is used, allowing us to reach a significant dissipation parameter. In our experiments, we have observed an adiabatic gradient of 3~K/cm and the power law between the superadiabatic Rayleigh number and the Nusselt number measuring the turbulent heat transfer is characterized by an exponent 0.3.Measurements of temperature and pressure fluctuations show that the flow is quasi-geostrophic as a result of the strong rotation rate of the centrifuge. An anelastic, quasi-geostrophic model has then been developed and solved numerically in the same configuration as the experiments.

Cette thèse porte sur certaines extensions des automates pondérés, et étudie les séries qu’ils réalisent en fonction de la nature des poids.Ces extensions se distinguent par les mouvements supplémentaires autorisés à la tête de lecture de l’automate : retour au début du mot pour les automates circulaires, changement de sens de lecture pour les automates boustrophédons.Dans le cas général, les automates pondérés circulaires sont plus puissants que les automates unidirectionnels classiques, et moins puissants que les boustrophédons.On introduit de plus les expressions de Hadamard, qui sont une extension des expressions rationnelles et qui permettent de dénoter le comportement des automates circulaires. Les aspects algorithmiques de cette conversion sont étudiés dans le cas où les poids appartiennent à un semi-anneau rationnellement additif.On montre que lorsque les poids sont des nombres rationnels, réels ou complexes, les automates circulaires sont aussi expressifs que les boustrophédons.Enfin, si les poids forment un bi-monoïde localement fini, les automates boustrophédons ne sont pas plus expressifs que les automates pondérés classsiques. / This thesis deals with some extensions of weighted automata,and studies the series they can realisedepending on the nature of their weigths.These extensions are characterised by howthe input head of the automaton is allowed to move:rotating automata can go back at the beginning of the word,and two-way automata can change the reading direction.In the general setting, weigthed rotating automata are morepowerful than classical one-way automata, and less powerfulthan two-way ones.Moreover, we introduce Hadamard expressions,which are an extension of rational expressions and can denotethe behaviour of rotating automata.The algorithms for this conversion are studied when the weights belong toa rationally additive semiring.Then, rotating automata are shown as expressive as two-way automatain the case of rational, real or complex numbers.It is also proved that two-way and one-way automataare equivalent when weighted on a locally finite bimonoid.

Ce manuscrit porte sur les transitions compressible-incompressible dans les équations aux dérivées partielles de la mécanique des fluides. On s'intéresse à deux problèmes : les structures flottantes et les fluides en rotation. Dans le premier problème, l'introduction d'un objet flottant dans les vagues induit une contrainte sur le fluide et les équations gouvernant le mouvement acquièrent une structure compressible-incompressible. Dans le deuxième problème, le mouvement de fluides géophysiques compressibles est influencé par la rotation de la Terre. L'étude de la limite à rotation rapide montre que le champ vectoriel de vitesse tend vers une configuration horizontale et incompressible.Les structures flottantes constituent un exemple particulier d'interaction fluide-structure, où un solide partiellement immergé flotte à la surface du fluide. Ce problème mathématique modélise le mouvement de convertisseurs d'énergie marine. En particulier, on s'intéresse aux bouées pilonnantes, installées proche de la côte où les modèles asymptotiques en eaux peu profondes sont valables. On étudie les équations de Saint-Venant axisymétriques en dimension deux avec un objet flottant à murs verticaux se déplaçant seulement verticalement. Les hypothèses sur le solide permettent de supprimer le problème à bord libre associé avec la ligne de contact entre l'air, le fluide et le solide. Les équations pour le fluide dans le domaine extérieur au solide sont donc écrites comme un problème au bord quasi-linéaire hyperbolique. Celui-ci est couplé avec une EDO non-linéaire du second ordre qui est dérivée de l'équation de Newton pour le mouvement libre du solide. On montre le caractère bien posé localement en temps du système couplé lorsque que les données initiales satisfont des conditions de compatibilité afin de générer des solutions régulières.Ensuite on considère une configuration particulière: le retour à l'équilibre. Il s'agit de considérer un solide partiellement immergé dans un fluide initialement au repos et de le laisser retourner à sa position d'équilibre. Pour cela, on utilise un modèle hydrodynamique différent, où les équations sont linearisées dans le domaine extérieur, tandis que les effets non-linéaires sont considérés en dessous du solide. Le mouvement du solide est décrit par une équation intégro-différentielle non-linéaire du second ordre qui justifie rigoureusement l'équation de Cummins, utilisée par les ingénieurs pour les mouvements des objets flottants. L'équation que l'on dérive améliore l'approche linéaire de Cummins en tenant compte des effets non-linéaires. On montre l'existence et l'unicité globale de la solution pour des données petites en utilisant la conservation de l'énergie du système fluide-structure.Dans la deuxième partie du manuscrit, on étudie les fluides en rotation rapide. Ce problème mathématique modélise le mouvement des flots géophysiques à grandes échelles influencés par la rotation de la Terre. Le mouvement est aussi affecté par la gravité, ce qui donne lieu à une stratification de la densité dans les fluides compressibles. La rotation génère de l'anisotropie dans les flots visqueux et la viscosité turbulente verticale tend vers zéro dans la limite à rotation rapide. Notre interêt porte sur ce problème de limite singulière en tenant compte des effets gravitationnels et compressibles. On étudie les équations de Navier-Stokes-Coriolis anisotropes compressibles avec force gravitationnelle dans la bande infinie horizontale avec une condition au bord de non glissement. Celle-ci et la force de Coriolis donnent lieu à l'apparition des couches d'Ekman proche du bord. Dans ce travail on considère des données initiales bien préparées. On montre un résultat de stabilité des solutions faibles globales pour des lois de pression particulières. La dynamique limite est décrite par une équation quasi-géostrophique visqueuse en dimension deux avec un terme d'amortissement qui tient compte des couches limites. / This manuscript deals with compressible-incompressible transitions arising in partial differential equations of fluid mechanics. We investigate two problems: floating structures and rotating fluids. In the first problem, the introduction of a floating object into water waves enforces a constraint on the fluid and the governing equations turn out to have a compressible-incompressible structure. In the second problem, the motion of geophysical compressible fluids is affected by the Earth's rotation and the study of the high rotation limit shows that the velocity vector field tends to be horizontal and with an incompressibility constraint.Floating structures are a particular example of fluid-structure interaction, in which a partially immersed solid is floating at the fluid surface. This mathematical problem models the motion of wave energy converters in sea water. In particular, we focus on heaving buoys, usually implemented in the near-shore zone, where the shallow water asymptotic models describe accurately the motion of waves. We study the two-dimensional nonlinear shallow water equations in the axisymmetric configuration in the presence of a floating object with vertical side-walls moving only vertically. The assumptions on the solid permit to avoid the free boundary problem associated with the moving contact line between the air, the water and the solid. Hence, in the domain exterior to the solid the fluid equations can be written as an hyperbolic quasilinear initial boundary value problem. This couples with a nonlinear second order ODE derived from Newton's law for the free solid motion. Local in time well-posedness of the coupled system is shown provided some compatibility conditions are satisfied by the initial data in order to generate smooth solutions.Afterwards, we address a particular configuration of this fluid-structure interaction: the return to equilibrium. It consists in releasing a partially immersed solid body into a fluid initially at rest and letting it evolve towards its equilibrium position. A different hydrodynamical model is used. In the exterior domain the equations are linearized but the nonlinear effects are taken into account under the solid. The equation for the solid motion becomes a nonlinear second order integro-differential equation which rigorously justifies the Cummins equation, assumed by engineers to govern the motion of floating objects. Moreover, the equation derived improves the linear approach of Cummins by taking into account the nonlinear effects. The global existence and uniqueness of the solution is shown for small data using the conservation of the energy of the fluid-structure system.In the second part of the manuscript, highly rotating fluids are studied. This mathematical problem models the motion of geophysical flows at large scales affected by the Earth's rotation, such as massive oceanic and atmospheric currents. The motion is also influenced by the gravity, which causes a stratification of the density in compressible fluids. The rotation generates anisotropy in viscous flows and the vertical turbulent viscosity tends to zero in the high rotation limit. Our interest lies in this singular limit problem taking into account gravitational and compressible effects. We study the compressible anisotropic Navier-Stokes-Coriolis equations with gravitational force in the horizontal infinite slab with no-slip boundary condition. Both this condition and the Coriolis force cause the apparition of Ekman layers near the boundary. They are taken into account in the analysis by adding corrector terms which decay in the interior of the domain. In this work well-prepared initial data are considered. A stability result of global weak solutions is shown for power-type pressure laws. The limit dynamics is described by a two-dimensional viscous quasi-geostrophic equation with a damping term that accounts for the boundary layers.

<p>Osnovni cilj ove disertacije je da se razvije Integrisani model odrţavanja zasnovan na vibracijama sloţenih rotacionih tehniĉkih sistema, odnosno da se uspostavi sprovoĊenje dijagnostiĉkih provera stanja sklopova rotacionih ma&scaron;ina (kontrola vibracija). Zatim da se defini&scaron;u optimalne periodiĉnosti vibracija kao i identifikacija ocena i rangiranja rizika sa stanovi&scaron;ta prekida rada ma&scaron;ina. Na taj naĉin potvrdiće se glavna hipoteza koja glasi: &bdquo;Razvijanjem integrisanog modela odrţavanja zasnovanog na uspostavljanju zakonitosti promene mehaniĉkih vibracija moći će da se preventivno predvide pojave neispravnosti i prognozira stanje rotacionih ma&scaron;ina.</p> / <p>The basic goal of this dissertation is the development of an Integrated Maintenance Model based on vibrations of complex rotational technical systems, in other words, the establishment of implementation of diagnostic checks of rotating machinery compositions condition (control of vibrations). Afterwards, the definition of optimal periodicity of vibrations, as well as identification of estimations and ranking of risks from the stand point of disruption of work of operational processes. This is the way to confirm the main hypothesis which reads: &ldquo;Development of an Integrated Maintenance Model based on the establishment of legality of change of mechanical vibrations will enable preventive predicting of malfunction occurrence, as well as prognosis of rotating machinery health.</p>