A passagem de um padrão monsoonal para um padrão de circulação atmosférica zonal ocorreu durante o Cretáceo devido à fragmentação do Supercontinente Gonduana. Essa mudança na direção dos paleoventos é registrada no mergulho de estratos cruzados de dunas eólicas acumuladas em várias bacias de Gonduana. Três mapas de reconstrução de paleoventos foram construídos com a integração de dados paleocorrentes compilados de bacias Fanerozoicas brasileiras, Bacia de Neuquén na Argentina e bacias do Congo e Huab na África. O Gonduana foi dominado por ventos do nordeste ao norte e ventos do sudoeste ao sul, deslocando, assim, a Zona de Convergência Intertropical para 15º a 20 sul do equador durante o Jurássico Tardio até o início do Cretáceo. Por sua vez, os ventos apresentaram uma tendência geral para o oeste-noroeste em latitudes baixas e médias no Gonduana no final do Cretáceo Inical. Esses resultados apontam para a existência de um padrão monsoonal durante o Jurássico Tardio até o início do Cretáceo Inicial e a entrada do padrão zonal no final do Cretáceo Inicial, associado à fragmentação de Gonduana. / The passage of a monsoonal pattern to a zonal atmospheric circulation pattern occurred during the Cretaceous due to fragmentation of Gondwana Supercontinent. This change in the paleowind direction is recorded in crossstrata dip directions of eolian dunes accumulated in various basins of Gondwana. Three maps of paleowind reconstruction were built with integration of compiled paleocurrent data from Phanerozoic basins in Brazil, Neuquén Basin in Argentina and Congo Basin and Huab Basin in Africa. Gondwana was dominated by northeast winds to the north and southwest winds to the south, thus shifting the Intertropical Convergence Zone to 15º to 20⁰ south of the equator during Late Jurassic to the beginning of the Cretaceous. In turn, winds had a general tendency towards west-northwest at low and mid-latitudes in Gondwana at the end of Early Cretaceous. These results point to the existence of a monsoonal pattern during the Late Jurassic to the beginning of Early Cretaceous and the entry of zonal pattern at the end of Early Cretaceous, associated with fragmentation of Gondwana.

A fusão zonal compreende uma família de métodos para controle e distribuição de impurezas na qual uma pequena zona fundida é deslocada lentamente ao longo de um material sólido, redistribuindo o soluto. Ela é utilizada na purificação de materiais, num processo denominado refino zonal, mas também pode ser usada na distribuição homogênea ou descontínua de impurezas e no crescimento de cristais. A fusão zonal aplicada ao crescimento de grãos, visando a obtenção de materiais mono ou policristalinos com grãos grosseiros é denominada recristalização por fusão zonal (ZMR) e seu uso principal é na preparação de materiais para fabricação de dispositivos eletrônicos e fotovoltaicos, especialmente em silício. Na última década, o progresso na tecnologia ZMR foi feito principalmente em três campos: desenvolvimento de equipamento, controle de processo e modelagem numérica, mas somente algumas pesquisas abordam a fusão zonal a baixas temperaturas e restringem a aplicação do método a outros materiais semicondutores como os elementos do grupo III, IV ou V. Deste modo, o presente trabalho tem como objetivo verificar a influência da velocidade de varredura, da largura da zona fundida e do número de passadas no processo de fusão zonal de materiais de baixo ponto de fusão, em relação à obtenção de materiais policristalinos com grãos grosseiros. Para tanto, construiu-se um equipamento de fusão zonal horizontal e barras de alumínio puro (P0610) foram submetidas ao processo, variando os parâmetros acima referidos. A macroestrutura das amostras foi analisada e os resultados obtidos do número de grãos/área foram interpretados, verificando a influência dos parâmetros físicos anteriormente citados, do gradiente térmico e do super-resfriamento constitucional. Verificou-se que a redução na velocidade de varredura e na largura da zona fundida, de modo geral, mostrou-se eficiente em relação à diminuição do número de grãos por área. Os resultados obtidos indicam que a fusão zonal foi efetiva na obtenção de alumínio policristalino com grãos grosseiros e colaboram para melhorar a compreensão do processo. / The zone melting comprises a family of methods to control and to distribute impurities in which a small molten zone is moved slowly along a solid material, redistributing solute. It is used in materials purification, in a so-called zone refining process, but can also be used in homogeneous or discontinuous distribution of impurities and crystal growth. The zone melting applied to grain enlargement, leading to attain singlecrystalline or polycrystalline materials with coarse grains is so-called zone melting recrystallization (ZMR) and its major use is the preparation of materials for electronic and photovoltaic devices process especially silicon. In the last decade, progress in ZMR technology was done mainly in three areas: equipment development, process control, and numerical modeling, but only a few researches handle on zone melting at low temperatures and it limits the application of the method to other semiconductor materials such as III, IV or V group elements. Thus, this study aims to examine the influence of scan rate, zone width and the number of zone passes in the zone melting process of low melting point materials about getting polycrystalline materials with coarse grains. For this, horizontal zone melting equipment was built and pure aluminum bars (P0610) were zone melted, varying the parameters mentioned above. The macrostructure of the samples was analyzed and the results of the number of grains per area were assessed by checking the influence of physical parameters previously mentioned and the thermal gradient and the constitutional supercooling. It was found that scan rate and zone width reduction in general, proved to be efficient in reducing the number of grains per area. The results indicate that the zone melting was effective in obtaining aluminum polycrystalline coarse-grained and collaborate to improve the understanding of the process.

Orientador: Paulo Roberto Mei / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-14T07:44:38Z (GMT). No. of bitstreams: 1 Moreira_SimonedePaula_D.pdf: 8445181 bytes, checksum: a58955df1f5c0b0b975a053856fe9dc0 (MD5) Previous issue date: 2009 / Resumo: A busca por fontes renováveis de energia fez com que a produção de células solares apresentasse um crescimento explosivo nesta década, passando de 0,3 GW em 2002 para 6,0 GW em 2008, envolvendo em 2008 a cifra de 37 bilhões de dólares. A produção de Silício Grau Eletrônico (SiGE) aumentou 127% de 2007 para 2008, sendo que cerca de 90% das células solares produzidas atualmente utiliza o SiGE, que é responsável por 1/4 do custo total da instalação de um painel solar. O processo de purificação de silício utilizado em todo o mundo é o Siemens, baseado na cloração do silício, o qual possui o inconveniente de gerar resíduos químicos de alta toxidade. Esse processo produz o silício de alta pureza, com menos de 1 ppm de impurezas, chamado de Silício Grau Eletrônico (SiGE), usado tanto pela indústria microeletrônica como a de produção de células solares. Para suprir tal demanda de silício para a área fotovoltaica, existem duas alternativas. A primeira visa desenvolver processos químicos derivados do Siemens para produzir um silício de qualidade inferior e de menor custo, denominado de Silício Grau Solar (SiGS), mas que atenda a exigência para a fabricação de células solares. A segunda alternativa é tentar adaptar etapas metalúrgicas de purificação ao silício de grau metalúrgico (SiGM), de forma a obter um silício com exigências a um SiGS, foco deste trabalho. As possibilidades de inserção do Brasil no mercado fotovoltaico são muito grandes, pois além de possuir a maior reserva mundial de quartzo, é o terceiro maior produtor de silício metalúrgico do mundo e o exporta a, aproximadamente, U$ 1/kg. Entretanto a agregação de tecnologia na purificação do silício eleva exponencialmente o seu valor, chegando a US$ 100 /kg para o silício policristalino de grau eletrônico ou até US$ 4.000/kg para lâminas de silício mono e policristalino da mesma pureza. O Departamento de Engenharia de Materiais da Unicamp pesquisa o SiGS desde 1980, tendo obtido naquela época, através da lixiviação ácida e solidificação unidirecional de SIGM, um lingote com 170 ppm de impurezas metálicas na sua região mais pura. Deste lingote foram produzidas células solares com eficiência de 4 % no Instituto de Física da Unicamp. A partir de 1990, com compra de um forno de feixe de elétrons, iniciaram-se os estudos sobre a purificação do SiGM neste equipamento, tendo sido observada numa amostra circular, solidificada a 10 mm/min, a segregação radial de impurezas, com uma redução de 1100 para 15 ppm na região mais pura da amostra. Os resultados obtidos nos levaram a estudar o potencial de purificação de silício metalúrgico no forno EBM com a técnica de fusão zonal horizontal, utilizando cadinhos de cobre refrigerado à água e de grafita, com diferentes velocidades de avanço de zona (1 e 10 mm/min), foco deste trabalho. As vantagens do processo de fusão zonal horizontal (com cadinho) sobre o de fusão zonal vertical ou flutuante (sem cadinho) é que o controle do tamanho da zona é bem mais simples no primeiro, além de permitir o uso de silício em qualquer forma (pedras, granulado ou lingotes) enquanto que para o segundo somente podem ser utilizadas barras de silício Os resultados obtidos utilizando-se o SiGM fornecido pela empresa Liasa com teor total de impurezas de 1454 ppm e mais de 100 ppm de carbono e 30 ppm de oxigênio e o SiGM fornecido pela empresa Rima, com teor total de impurezas de 254 ppm e mais 140 ppm de carbono e 2500 ppm de oxigênio foram os seguintes: - O uso de cadinho de cobre refrigerado a água foi adequado, pois permitiu fácil desmoldagem do lingote sem contaminar o silício. Com 1 passada de fusão zonal em 2 lingotes, numa velocidade de 1 mm/min e uma nova passada no lingote formado pelas duas metades mais limpas, permitiu a obtenção de um teor total de impurezas de 25 ppm com silício Liasa e menos de 11 ppm com o silício Rima. O teores de carbono e oxigênio foram reduzidos para 35 e 6 ppm respectivamente, no silício Liasa e 40 e 10 ppm, no silício Rima, valores próximos do SiGE da Wacker, com 20 e 12 ppm. A perda de massa do silício por evaporação ficou em torno de 6% por passada, o que limita a aplicação da fusão zonal para um grande número de passadas; - Embora o cadinho de cobre forneça um silício bastante puro (5 noves ou 99,999%) o lingote apresentou trincas internas de solidificação e não pode ser usado diretamente na produção de células solares. Outro processo de solidificação (CZ ou HEM) posteriormente ao processo de fusão zonal deveria ser usado, obtendo assim lingote de melhor qualidade estrutural; - Todas as impurezas metálicas analisadas (Al, Co, Cr, Cu, Fe, Mn, Mo, Nb, Ni, Ti, V, W e Zr) além de boro e fósforo foram segregadas para o final do lingote. Além da segregação, houve a purificação por evaporação principalmente do fósforo, seguido em menores proporções de manganês, alumínio e cobre. O coeficiente de distribuição efetivo (K) de cada elemento mostrou ser dependente do teor total de impurezas e quanto maior o teor total de impurezas, maior foi o valor de K. O boro foi pouco afetado pelo processo de fusão zonal, pois não evapora e tem solubilidade próxima no sólido e no líquido; - O uso de cadinho de grafita no lugar do cadinho de cobre refrigerado a água, reduziu o consumo de energia em 20% e proporcionou a produção de um lingote de silício com boa pureza e melhor qualidade estrutural, com ausência de trincas internas. O contato do silício com o cadinho provocou, entretanto, a contaminação do silício pelo carbono e a formação de uma camada superficial de carboneto de silício, de extrema dureza, o que dificulta ou impede o corte das lâminas. Houve a quebra do cadinho de grafita durante a fusão ou a desmoldagem. Cadinhos especiais como FABMATE e SuperSiC também apresentaram a adesão do silício e quebraram; - A resistividade elétrica não mostrou correlação com o teor total de impurezas, ficando em torno de 0,08±0,04 ohm.cm para lâminas com teor total de impurezas entre 10 e 10.000 ppm. A resistividade elétrica também não mostrou correlação direta com a eficiência solar nas amostras produzidas; - A eficiência solar não mostrou relação direta com o teor total de impurezas, mas sim com a qualidade estrutural do lingote, pois as células que apresentaram maior eficiência foram produzidas no cadinho de grafita, onde as lâminas não apresentavam trincas de solidificação. / Abstract: The search for renewable energy sources has caused a boom in the production of solar cells in this decade, which rose from 0.3 GW in 2002 to 6.0 GW in 2008, totaling 37 billion dollars in 2008. The production of Electronic Grade Silicon (SiGE) increased 127% from 2007 to 2008, and approximately 90% of solar cells produced nowadays use SiGE, which is responsible for 1/4 of the total installation cost of a solar panel. The Siemens process is used all over the world to purify silicon. It is based on the chlorination of silicon and has the disadvantage of generating highly toxic chemical waste. This process produces high-purity silicon with less than 1 ppm impurities, called Electronic Grade Silicon (SiGE). It is used by the microelectronics industry and in the production of solar cells as well. There are two alternatives to meet the demand for silicon for the photovoltaic area. The first one, called Solar Grade Silicon (SiGS), aims to develop a chemical processes, derived from the Siemens process, to produce lower-quality silicon at lower costs, but which still meets the requirements for solar cell manufacture. The second alternative is to try to adapt the metallurgical purification steps of metallurgical grade silicon (SiGM) to obtain silicon that meets SiGS requirements, which is the focus of this work. The possibilities of insertion of Brazil in the photovoltaic market are very large because, besides having the largest quartz reserves in the world, it is the third largest producer of metallurgical silicon in the world and exports it at about U$ 1/kg. However, the aggregation of technology in silicon purification increases its value exponentially, reaching U$100/kg for electronic grade polycrystalline silicon and up to U$ 4.000/kg for layers of mono and polycrystalline silicon, with the same purity. The Department of Materials Engineering of Unicamp has researched SIGS since 1980, having obtained an ingot with 170 ppm metallic impurities in its purest region by acid leaching and unidirectional solidification of SiGM at that time; solar cells with 4% efficiency were produced from this ingot at the Institute of Physics at Unicamp. In 1990, with the purchase of an electron beam furnace, studies on the purification of SiGM in this equipment were started. Radial segregation of impurities was observed in a round sample solidified at 10 mm/min, with a reduction from 1100 to 15 ppm in its purest region. The results led us to study the potential for purification of metallurgical silicon in the EBM furnace with the horizontal zone melting technique, using water-cooled copper and graphite crucibles, with different zone advance speeds (1 and 10 mm/ min), which is the focus of this work. The advantages of the horizontal zone melting process (with crucible) over the vertical zone melting or floating (without crucible) process is that the control of the size of the zone is much simpler in the former, besides allowing the use of silicon in any shape (stones, granulated or ingots), while only silicon bars can be used in the latter. The results obtained using the SiGM provided by Liasa, with 1454 ppm total impurities content and more than 100 ppm and 30 ppm of carbon and oxygen, and the SiGM supplied by Rima Company, with 254 ppm total impurities content and 140 ppm carbon and 2500 ppm oxygen, were as follows: - The use of the water-cooled copper crucible was adequate because it allowed easy shakeout, with no silicon contamination. With 1 melting zone pass along 2 bars, at a speed of 1 mm/min, and a new pass along the ingot formed by the two cleanest halves, we obtained a total of 25 ppm impurities content with Liasa silicon and less than 11 ppm with Rima silicon. Carbon and oxygen contents were reduced to 35 and 6 ppm, respectively, in Liasa silicon and 40 and 10 ppm in Rima silicon; these values are near Wacker SiGE values of 20 and 12 ppm. The loss of silicon mass by evaporation was around 6% per pass, which limits the application of zone melting for a large number of passes; - Although the copper crucible leads to extremely pure silicon (5 nines or 99,999%) the ingot presented internal solidification cracks and cannot be used directly in the production of solar cells. Another solidification process (CZ or HEM) should be used after the zone melting process, leading to an ingot with better-quality structure; - All metal impurities analyzed (Al, Co, Cr, Cu, Fe, Mn, Mo, Nb, Ni, Ti, V, W and Zr), besides boron and phosphorus, were segregated towards the end of the block. Besides segregation, there was purification of phosphorus, mainly by evaporation, followed by smaller proportions of manganese, aluminum and copper. The effective distribution coefficient (K) of each element was shown to be dependent on the total impurities content, and the higher the total impurities content, the higher the value of K is. Boron was little affected by the zone melting process because it does not evaporate and its solubility is similar in the liquid and in the solid phases; - The use of the graphite crucible, instead of the water-cooled copper crucible, reduced energy consumption in 20% and led to the production of a silicon ingot with good purity and better structural quality, without internal cracks. The contact of silicon with the crucible has, however, caused the contamination of silicon by carbon and formed an extremely hard surface layer of silicon carbide, which makes it difficult to cut the layers or even prevents it. The graphite crucible broke during melting or shakeout. Special crucibles, such as FABMATE and SuperSiC, also suffered silicon adhesion and broke; - The electrical resistivity showed no correlation with the total impurities content, remaining around 0.08 ± 0.04 ohm.cm for samples with total impurities content between 10 and 10,000 ppm. The electrical resistivity also showed no direct correlation with solar efficiency in the samples produced.; - The solar efficiency showed no direct relationship to the total impurities content, but it showed a direct relationship to the structural quality of the ingot, as the higher efficiency cells were produced in the graphite crucible, with no solidification cracks in the layers; / Doutorado / Materiais e Processos de Fabricação / Doutor em Engenharia Mecânica

Connaitre précisément la structure interne des corps célestes est indispensable pour, à la fois, comprendre la physique qui régit leur existence et le processus qui leur a donné naissance. La sismologie, d’abord appliquée à la Terre puis au soleil, s’est révélée être un outil très efficace pour sonder leurs intérieurs. Dans les années 70 (Vorontsov et al 1976), des premiers travaux théoriques ont étudié la possibilité d’une sismologie des planètes géantes gazeuses. Les premières tentatives de mesures d’oscillations ont eu lieu à la fin des années 80. La détection des modes d’oscillations de Jupiter s’est avérée une entreprise très délicate en raison de sa rotation rapide. Pour augmenter les chances de détection, un instrument spécifique a été construit au début des années 2000 à l’OCA. Cet instrument, appelé SYMPA, est un spectromètre imageur de type Mach-Zehnder capable de produire une carte de vitesse radiale de Jupiter. Une détection de modes d’oscillations sur Jupiter par cet instrument a été publiée par Gaulme et al en 2011. Une version améliorée de l’instrument (appelé DSI) a été proposée pour la mission spatiale JUICE à destination de Jupiter, et un nouveau prototype a été construit dans ce but. Par la suite, le projet s’est réorienté vers un programme d’observation depuis le sol sous la forme d’un réseau de trois télescopes répartis en longitude (USA, France, Japon) et financé par l’ANR à partir de 2015 (ANR JOVIAL). L’intérêt de la mise en réseau est d’assurer la continuité des données (météo mise à part). L’instrument étant capable de produire des cartes de vitesse radiales, le projet permet également l’étude de la dynamique atmosphérique des planètes géantes. Ce travail de thèse s’inscrit dans le contexte de préparation de JOVIAL, avec pour objectif de caractériser l’instrument en laboratoire et d’identifier les problèmes liés aux conditions réelles d’observation. Les mesures en laboratoires ont montré des performances conformes aux attentes, avec un bruit de mesure propre à l’instrument inférieur au bruit de photon attendu sur Jupiter. Les premières mesures sur le ciel avec un télescope ont mis en évidence une sensibilité de l’instrument au degré de polarisation de la lumière ainsi qu’une dérive de la vitesse mesurée liée aux instabilités de position de la pupille pendant les observations. Le design de l’instrument et de son interface avec le télescope a été revu pour résoudre ces problèmes. Plusieurs campagnes d’observations de Jupiter ont été réalisées, permettant de mettre sur pied une chaine complète de traitement des données, dont la validité a été vérifiée par des simulations réalistes. Les observations de Jupiter ont donné des résultats scientifiques particulièrement intéressants. L’analyse des données de deux campagnes de 2015 et 2016 a fourni des séquences temporelles de cartes de vitesses radiales de Jupiter. Une première étude a consisté à chercher dans ces cartes la signature des vents zonaux et de les comparer aux mesures réalisées par suivi des nuages sur des images résolues (cloud-tracking). Une telle mesure n’avait jamais été faite par effet Doppler. Le résultat, bien qu’affecté par des biais de mesures identifiés, montre des profils de vents stables d’une année sur l’autre et en cohérence avec les valeurs issues du cloud-tracking, sauf au niveau de la partie nord de la bande équatoriale de Jupiter. La mesure Doppler suggère en effet une vitesse de vent bien inférieure à la vitesse apparente dans cette zone, ce qui a potentiellement des implications sur les modèles de dynamique atmosphérique. Ces résultats sont très importants pour mieux comprendre les mesures de la sonde Juno, actuellement en orbite autour de Jupiter. L’analyse fréquentielle des données temporelles a été abordée en fin de thèse. Les analyses préliminaires ne semblent pas pour l’instant reproduire la détection de SYMPA. Une analyse plus poussée est nécessaire avant de conclure à une absence du signal. / To know precisely the internal structure of the celestial bodies is essential to both to understand the physics which governs their existence, and the process which gave them birth. First applied to the Earth and then to the sun, seismology has proven to be a very effective tool to sound their interiors. It has become natural and legitimate to question the possibility of seismology of gaseous giant planets. The first theoretical work was carried out in the 1970s (Vorontsov et al. 1976), and the first attempts to measure oscillations at the end of the 1980s. The detection of Jupiter's oscillating modes turned out to be very difficult (reduced flux, small apparent diameter, fast rotation ...). To increase the chances of detection, a specific instrument was built in the early 2000s at the OCA. This instrument, called SYMPA, is a Mach-Zehnder-type imaging spectrometer enable to produce radial velocity maps of Jupiter. A first detection of acoustic modes on Jupiter with this instrument was published by Gaulme et al in 2011. An improved version of the instrument (called DSI), based on the same principle, was built in the wake, with the primary objective of boarding a spacecraft to Jupiter. The project was finally reoriented towards an observation program from the ground in the form of a network of three telescopes equidistant in longitude (USA, France, Japan) and supported by the ANR fund starting in 2015 (ANR JOVIAL). The interest of the network is to ensure the continuity of data (weather apart). The instrument being able to produce radial velocity maps, the project also aims to study the atmospheric dynamics of giant planets. This thesis work is part of a preparation for JOVIAL, with the aim of characterizing the instrument and identifying the problems related to real observations conditions. Laboratory measurements showed expected performances with an instrumental noise level (related to thermal fluctuations) lower than expected photon noise on Jupiter. The first measurements on the sky with a telescope showed a sensitivity of the instrument to the degree of polarization of the light as well as drifts of the velocity measurements due the motions of the pupil position. Some adjustments of the design of the instrument and its interface with the telescope were necessary to solve these issues. Several Jupiter observation campaigns were carried out during the thesis, allowing the development of full data processing software. The complete procedure was tested against simulated data and validated. Two observations runs in 2015 and 2016 were analyzed to produce time sequences of radial velocity maps of Jupiter, providing very interesting scientific results. First, the maps were analyzed to look for the signature of the zonal winds and to compare them with the measurements made by cloud-tracking. Such measurements by Doppler effect were never made before. The result, albeit affected by measurement biases, showed stable year-to-year wind patterns and coherent results with cloud-tracking measurements, except at the northern part of the Jovian’s equatorial band. The Doppler measurement indeed suggests a wind speed well below the apparent speed in this area, which potentially has implications for the theory of atmospheric dynamics and will be helpful to interpret the Juno (a spacecraft presently orbiting Jupiter) measurements. Frequency analysis of temporal data was undertaken at the end of the thesis. The preliminary results do not seem for the moment to reproduce the SYMPA detection. Further analysis is necessary before concluding if the signal is absent or attenuated.

Presently, there is a four-year window to prepare engines for upcoming TIER V regulations through solutions for peak power shaving and downsizing of diesel engines. In particular, Non-road mobile machinery(NRMM) offer a promising and challenging field of application due to their duty cycles, which includes high and short power peaks and extreme working conditions. In this paper, a series hybrid electric powertrain for a mining loader is presented with the goal of reducing the fuel consumption. A full-scale mining loader powertrain prototype was built to exploit the benefits of a series hybrid electric powertrain at low traction requirements with a combination of decentralized e.g. zonal hydraulics. Corespondingly, this paper introduces the structure of the mining loader and initial mathematical model of the system of a Direct Driven hydraulics (DDH). In this research, an experimental test was conducted, and the initial results are presented in this paper.

Mesosphere/lower thermosphere (MLT) zonal winds measured by a VHF meteor radar at Collm, Germany (51.3°N, 13.0°E) during late winter 2015/2016 show very strong westerly winds above about 90 km, but not below that height. This anomaly appears during a very strong El Niño event. The comparison of Niño3 equatorial sea surface temperature index and the Collm MLT wind time series starting in 2004 shows that in January and especially in February zonal winds are positively correlated with the Niño3 index. The signal is strong for the upper altitudes (above 90 km) accessible to the radar observations, but weakens with decreasing height. This reflects the fact that during El Niño years the westerly winter middle atmosphere wind jet is weaker on an average, and this is also the case with the easterly lower thermospheric jet. The El Niño effect on the meridional wind is weak. The experimental results can be qualitatively reproduced by numerical experiments using the MUAM mechanistic global circulation model with prescribed tropospheric temperatures and latent heat release for El Niño and La Niña conditions. / Der Zonalwind in der oberen Mesosphäre/unteren Thermosphäre über Collm (51.3°N, 13.0°E) in der zweiten Hälfte des Winter 2015/2016 weist eine besonders starke westliche Komponente oberhalb von etwa 90 km auf. Diese Anomalie erfolgte während eines sehr starken El Niño-Ereignisses. Der Vergleich von Collmer Zonalwinden seit 2004 und dem Niño3-index zeigt im Januar und besonders Februar eine positive Korrelation. Diese ist stark oberhalb von 90 km, nimmt aber nach unten hin ab. Dies spiegelt die Tatsache wider, dass während El Niño-Jahren im Mittel der stratosphärische/mesosphärische Westwindjet schwächer ist. Dieses Signal kehrt aber in der oberen Mesosphäre um, so dass der thermosphärische Ostwindjet ebenfalls schwächer ist. Der Effekt auf den meridionalen Wind ist schwächer. Die Beobachtungen können mit Modellexperimenten qualitativ reproduziert werden.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第20881号 / 理博第4333号 / 新制||理||1622(附属図書館) / 京都大学大学院理学研究科数学・数理解析専攻 / (主査)准教授 梅田 亨, 教授 上 正明, 教授 雪江 明彦 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

Une grande quantité d'énergie est présente dans les mouvements de rotations propre et orbitale des planètes. Des forçages harmoniques tels que les déformations de marées, la précession ou la libration peuvent en convertir une partie pour générer des écoulements dans les couches fluides d'une planète. Ces écoulements restent largement méconnus même s'ils sont importants pour contraindre des modèles d'intérieur planétaire ou expliquer la présence de champs magnétiques dans certains astres.Dans cette thèse, nous étudions les mécanismes engendrés par ces forçages en combinant une approche théorique, expérimentale et numérique et soulignons la généricité des phénomènes observés. L'étude d'un forçage de libration longitudinale, i.e. des oscillations de la vitesse de rotation d'un astre, montre la présence d'un écoulement zonal généré par des interactions non-linéaires dans les couches visqueuses. Nous étudions ensuite l'instabilité qui apparaît à la paroi pour des amplitudes de libration suffisantes et qui peut transférer de l'énergie vers le volume du fluide. Finalement, une étude expérimentale de forçage de marées dans une sphère met en évidence que l'excitation directe d'ondes inertielles induit un écoulement zonal intense et localisé. Cet écoulement peut se déstabiliser par une instabilité de cisaillement et générer un écoulement turbulent dans tout le volume.Pour finir, nous considérons la pertinence de ces résultats pour des applications géo-/astrophysiques, telles que l'étude des océans internes sous la surface de glace des satellites joviens Ganymède, Encelade et Europe. / A huge amount of energy is stored in the spin and orbital motions of any planet. Harmonic forcings such as libration, precession and tides are capable of conveying a portion of this energy to drive intense three-dimensional flows in liquid layers of planetary bodies. The generated flows remain largely unknown even if they are important to constraint model of planetary interior or to explain the presence of magnetic fields in some astrophysical bodies.In this thesis, we study the mechanisms induced by these forcings by combining theoretical, experimental and numerical approaches and we highlight the genericity of the observed phenomena. The study of a longitudinal libration forcing, corresponding to oscillations of the rotation rate of a planet, shows the presence of a mean zonal flow generated by non-linear interactions in the viscous layers. We then study the instability which appears at the outer boundary at sufficiently large libration amplitude or small Ekman number and which can transfer energy to the bulk of the fluid. Finally, an experimental study of tidal forcing in a sphere shows that the nonlinear self-interaction of excited inertial waves may drive an intense and localised axisymmetric jet, which becomes unstable at low Ekman number following a shear instability, generating space-filling turbulence.To conclude, we consider the relevance of these results to geo-/astrophysical applications, such as the subsurface oceans of the icy satellites Ganymede, Enceladus or Europa.

This paper discusses the potential of centralized or decentralized electro-hydraulic (EH)-drives in comparison to conventional hydraulic systems. The systems are presented in diagrams covering the major electric and hydraulic components for an exemplary application, but also include specific technical data like the sizing of the components according to power, pressure, rotational speeds etc. In a second step, all systems are compared and evaluated based on criteria like design effort, energy saving potential, controllability, and servicing and maintenance of the machine. The resulting effects on fuel consumption are summarized as well. Finally, an evaluation of the potential of EH-drives in construction machinery and a derivation of the demands for future customization of electro-hydraulic linear drives is given on the basis of a SWOT-analysis from the point of view of a construction machinery OEM.

Cette thèse porte sur la dynamique des grandes échelles des écoulements géophysiques turbulents, en particulier sur leur organisation en écoulements parallèles orientés dans la direction est-ouest (jets zonaux). Ces structures ont la particularité d'évoluer sur des périodes beaucoup plus longues que la turbulence qui les entoure. D'autre part, on observe dans certains cas, sur ces échelles de temps longues, des transitions brutales entre différentes configurations des jets zonaux (multistabilité). L'approche proposée dans cette thèse consiste à moyenner l'effet des degrés de liberté turbulents rapides de manière à obtenir une description effective des grandes échelles spatiales de l'écoulement, en utilisant les outils de moyennisation stochastique et la théorie des grandes déviations. Ces outils permettent d'étudier à la fois les attracteurs, les fluctuations typiques et les fluctuations extrêmes de la dynamique des jets. Cela permet d'aller au-delà des approches antérieures, qui ne décrivent que le comportement moyen des jets.Le premier résultat est une équation effective pour la dynamique lente des jets, la validité de cette équation est étudiée d'un point de vue théorique, et les conséquences physiques sont discutées. De manière à décrire la statistique des évènements rares tels que les transitions brutales entre différentes configurations des jets, des outils issus de la théorie des grandes déviations sont employés. Des méthodes originales sont développées pour mettre en œuvre cette théorie, ces méthodes peuvent par exemple être appliquées à des situations de multistabilité. / This thesis deals with the dynamics of geophysical turbulent flows at large scales, more particularly their organization into east-west parallel flows (zonal jets). These structures have the particularity to evolve much slower than the surrounding turbulence. Besides, over long time scales, abrupt transitions between different configurations of zonal jets are observed in some cases (multistability). Our approach consists in averaging the effect of fast turbulent degrees of freedom in order to obtain an effective description of the large scales of the flow, using stochastic averaging and the theory of large deviations. These tools provide theattractors, the typical fluctuations and the large fluctuations of jet dynamics. This allows to go beyond previous studies, which only describe the average jet dynamics. Our first result is an effective equation for the slow dynamics of jets, the validityof this equation is studied from a theoretical point of view, and the physical consequences are discussed. In order to describe the statistics of rare events such as abrupt transitions between different jet configurations, tools from large deviation theory are employed. Original methods are developped in order to implement this theory, those methods can be applied for instance in situations of multistability.