Made available in DSpace on 2016-04-26T20:48:52Z (GMT). No. of bitstreams: 1 Yim Kyu Lee.pdf: 844652 bytes, checksum: 4c191989a678bd58df27a6ae41c712ad (MD5) Previous issue date: 2008-09-30 / This dissertation analyses the period of weakening of the U.S. dollar in the 2001-2007 period and the three possible scenarios: (i) the maintenance and adjustment of the freefloating currency system, through the prolonged effects of the devaluation of the dollar, (ii) the protracted decline of the dollar as world currency, with the transfer of all or part of its role to another currency, with the Euro as most likely candidate, (iii) U.S. reaction in the style of the Volcker s shock in 1979-1980. It discusses whether there are limits to the setting in which the dollar, in the role of main reserve currency, is issued in large quantities to cover the U.S. current account deficits and whether the world will keep financing these deficits and paying significant margins of contribution to the United States, the so-called "exorbitant privilege" of the country issuing the world currency. The dissertation studies the formation of the freefloating dollar standard after the collapse of the Bretton Woods system in 1971-73 and the stages of its development, highlighting the period from 2001, which was marked by a sharp decline in the value the dollar. We draw attention to the similarities with the period of weakening of 1974-1980, which led to strong reaction from the United States with the high increase of interest and the imposition of credit controls, a process known as "Volcker s shock" / A dissertação analisa o período de enfraquecimento do dólar nos anos 2001-2007 e as alternativas colocadas no momento: (i) sustentação e ajustamento do sistema dólar flexível, por meio dos efeitos da desvalorização prolongada do dólar; (ii) declínio prolongado da posição do dólar como moeda mundial, com a transferência total ou parcial de seu papel para outra moeda, tendo o euro como candidato óbvio; (iii) reação dos EUA no estilo do choque de Volcker de 1979-1980. Discute-se se há limites para a configuração em que o dólar, no papel de moeda de reserva principal, é emitido em grandes quantidades em razão dos déficits em transações correntes norte-americanos, e se o mundo manterá o financiamento destes déficits pagando uma margem de contribuição expressiva para os Estados Unidos, o chamado "privilégio exorbitante" do país emissor da moeda mundial. A dissertação analisa a formação do padrão dólar-flexível, após a ruptura do sistema de Bretton Woods, em 1971-73, e as etapas de seu desenvolvimento, com destaque para os anos recentes, a partir de 2001, período marcado pelo declínio acentuado do valor do dólar. Destacam-se as semelhanças com o período de enfraquecimento de 1974-1980 que conduziu à forte reação dos Estados Unidos, com a forte elevação dos juros e a imposição de controles de crédito, processo conhecido como "choques de Volcker"

O crescimento da exploração do petróleo e gás em águas ultraprofundas fez com que a demanda por unidades flutuantes crescesse e, com isso, aumentasse a ocorrência do fenômeno de Movimentos Induzidos por Vórtices (ou VIM, de Vortex-Induced Motions) que age em plataformas com casco cilíndrico, como é o caso das monocolunas e spars. Efeito natural desse aumento nas ocorrências foi um maior interesse pelo fenômeno de VIM, simplificadamente investigado em cilindros lisos e curtos como os utilizados nesta pesquisa. A fim de contribuir com o conhecimento dos fundamentos fluido-dinâmicos nesta área, foram investigados quatro diferentes cilindros flutuantes de baixa razão de aspecto, todos caracterizados pelo valor típico de L/D = 2 (comprimento imerso por diâmetro, onde L= 250 mm e D= 125 mm), mas com diferentes condições de arredondamento da extremidade imersa, estas caracterizadas por quatro razões distintas entre o raio de adoçamento e o raio do cilindro, especificamente r/R= 0,00; 0,25; 0,50 e 1,00. Com este objetivo de observar a resposta dos cilindros curtos sob efeito dos vórtices gerados em diferentes formatos de extremidade imersa, experimentos foram realizados no tanque de provas do Instituto de Pesquisas Tecnológicas do Estado de S~ao Paulo (IPT), compreendendo velocidades de reboque entre 0,024 a 0,154 m/s, ou seja, uma faixa de números de Reynolds entre 3.300 e 19.200. Os resultados de amplitude adimensional de resposta observados na direção transversal mostram influência moderada das modificações na extremidade imersa, ligeiramente mais acentuadas no modelo com razão de arredondamento de r/R=0,25, sendo que para este caso, as amplitudes máximas ficaram abaixo daquelas exibidas pelos demais modelos, com uma tendência geral de queda para as velocidades de reboque mais altas. A variação da geometria da extremidade imersa também influenciou moderadamente os resultados de amplitude adimensional de resposta na direção longitudinal, onde o modelo com r/R=1,00 apresentou menores amplitudes nas velocidades mais altas. Por outro lado, a razão entre as frequências de resposta e as frequências naturais de referência mostraram comportamentos típicos, semelhantes aos encontrados em análises de VIV de cilindros longos montados em suportes elásticos com dois graus de liberdade. Além disso, a observação dos movimentos dos modelos no plano da superfície livre não indicaram mudanças significativas nas trajetórias em função do arredondamento da extremidade livre. No tocante aos coeficientes de força (arrasto e sustentação), as comparações entre os modelos foram semelhantes, mas os coeficientes para o cilindro sem chanfro (r/R=0) mostraram-se maiores para grande parte das velocidades ensaiadas. Para o modelo com r/R=1,00, as força (arrasto e sustentação não se mostraram com a mesma intensidade do que aquelas nos demais modelos, o que, desta forma, se refletiu nos menores valores de coeficiente encontrados. Sob uma ótica geral, os resultados levam a crer que o modelo fluido responsável pelas oscilações nos cilindros com L/D = 2 não tem relação com a existência de vórtices de ponta e aresta, mas com a emissão de vórtices em forma de arco. / The oil and gas exploration in deep and ultra-deep water has increased in the past years, and at the same time, increasing the oating vessel demand, thereby the vortex-induced motion phenomenon (VIM) has been present for cylindrical hull structures, for example, spar and monocolumns oating units. The impact of this, enhance the VIM phenomenon interest with simplify investigations on smooth cylinders, as was used in the present research. In order to expand the knowledge, experiments were made in four floating cylinders with low aspect of ratio, L/D = 2 (Length / Diameter) were tested with different free end corner shape types, namely by the relation between chamfer rounding radius (r) divided by the radius of cylinder (R) (r/R = 0.0, 0.25, 0.5 and 1.0). For the initial case, r/R =0.0 represents at tip and r/R = 1.0 the semi-hemispherical tip. The aims were to understand the effect of different free-end types on VIV behaviour of cylinders. The oating circular cylinders, i.e. unit mass ratio m* = 1(structural mass/displaced uid mass), were elastically supported by a set of linear springs to provide low structural damping on the system and allow six degrees of freedom. The aim is to understand the effects of the free end vortex in the cylinder movements, varying the free end shape. The experiments were carried out in a towing tank of IPT - Institute for Technological Research of the state of São Paulo, Brazil. The range of velocities tested is 0.024 to 0.154 m/s , and Reynolds number covered 3;300 <= Re <= 19;200. The nondimensional amplitudes results for transversal direction, show a moderated effect when the free end shape has changed, more significant in the r/R=0.25 case, where the maximum amplitudes present lower values compare with the others cylinders. For in-line nondimensional amplitudes, model with r/R= 1.00 shown lower values for high velocities. On the other hand, the frequencies ratios between in-line/transverse and natural sistem frequency, presented typical VIV response for long cylinders with two degree of freedom. In addition, the trajectory observations in the XY plane have not illustrated differences for cylinders with rounded edges. Force coeffcients outcome (drag and lift), the no-rounded edge case (r/R=0.0), presented higher coeffcients for the large proportion velocities. Furthermore, the model with a semi-spherical shape in the free end (r/R=1.00), demonstrated the both force coeffcients have not acted with the same severity as was observed for the others cylinders, and thus, the r/R=1.00 models has presented lowest values. In general, the present results suggest the answer for oscillation on L/D=2 models is caused by arc-type vortex shedding, not by the free end vortex effects.

A separação de microrganismos fotossintetizantes no tratamento de efluentes possui dois aspectos fundamentais. O primeiro refere-se à qualidade do efluente tratado e seu impacto sobre os recursos hídricos e, o segundo, refere-se ao potencial deste material como fonte de energia renovável. Diversos trabalhos tem demostrado elevada eficiência na separação de algas no tratamento de efluentes. Entretanto, quando considerado o cultivo de microalgas para utilização da biomassa como matéria prima, para produção de biocombustível por exemplo, mais estudos científicos são necessários. Entre as operações de separação sólido-líquido, normalmente empregadas no tratamento de efluentes, a flotação por ar dissolvido tem se mostrado uma tecnologia vantajosa, pois, além de ser capaz de separar partículas com diâmetro reduzido e baixa velocidade de sedimentação, também permite a obtenção de um material flotado com maior percentual de sólidos, desejável para redução dos custos de processamento da biomassa algal. O objetivo deste trabalho foi avaliar a separação de microalgas cultivadas em uma lagoa de tratamento de esgoto de alta taxa através do processo de coagulação-floculação e flotação por ar dissolvido. Como contribuição aos estudos de separação por FAD, foi avaliado a estabilidade do material flotado submetido a uma agitação mecânica, utilizando a técnica de captura e análise de imagens digitais, segundo um parâmetro chamado porcentagem de área (αa) Este parâmetro é definido como o percentual de pixels pretos em relação ao total de pixels da imagem, e demonstra a instabilidade do material flotado. Os coagulantes cloreto férrico e Tanfloc SG (Tanac®) e os floculantes sintéticos do tipo poliacrilamidas (SNF Floerger®) catiônico (FO4550SH), aniônico (FA920SH) e não iônico (FA920SH) foram investigados em diferentes dosagens e combinações. O presente estudo mostrou que a separação de algas através deste sistema é viável tecnicamente, sendo que os melhores resultados apresentaram uma remoção de turbidez de 92% para a combinação de cloreto férrico (20mg/L) + FO4550SH (2mg/L) e 97% para Tanfloc SG (20mg/L) + AN956SH (1mg/L). Em relação à estabilidade do material flotado, as amostras que continham apenas coagulantes apresentaram valores de αa entre 4,26 e 5,49, indicando uma baixa estabilidade do material flotado. Enquanto as combinações de cloreto férrico (20mg/L) + FO4550SH(0.5mg/L) e Tanfloc SG (20mg/L) +FO4550SH (1 e 2mg/L) foram as que produziram um material flotado com maior estabilidade, apresentando αa=0,35 e αa=0,40, respectivamente, demonstrando que o uso dos polímeros proporciona uma maior estabilidade do material flotado, quando este está sujeito a turbulências. / Separation of photosynthetic microorganisms in the effluent treatment has two fundamental aspects. The first refers to the quality of the treated effluent and its impact on water resources, and the second refers to the potential of this material as a source of renewable energy. Several studies show high efficiency in the separation of algae in effluent treatment. However, more scientific studies are required considering the cultivation of microalgae for the use of them as a raw material for biomass, like biofuel for instance. Among solid-liquid separation operations normally employed in effluents treatment, dissolved air flotation has been shown to be an advantageous technology in order to separate algae, because allows not only the separation of particles with reduced diameter and low sedimentation velocity, but also produces a floating material with higher percentage of solids, which is desirable for reducing the processing costs of the algal biomass. The aim of this work was to evaluate the separation of microalgae originated on a high rate pond through the coagulation, flocculation and dissolved air flotation (DAF) processes. As a contribution to the DAF separation studies, the stability of the floating material was evaluated against mechanical agitation, using the technique of digital image analysis, according to a parameter called area percentage (αa) This parameter is defined as the percentage of pixels in relation to the total pixels of the image, and demonstrates the instability of the floating material. The ferric chloride and Tanfloc SG (Tanac®) coagulants and the synthetic flocculants polyacrylamide types (SNF Floerger®) cationic (FO4550SH), anionic (FA920SH) and nonionic (FA920SH) were investigated in different concentrations and combinations. The present study showed that algae separation through this system is technically feasible. The best results showed a turbidity removal of 92% for the combination of ferric chloride (20mg/L) + FO4550SH (2mg/L) and 97% for Tanfloc SG (20mg/ L) + AN956SH (1mg/L). In relation to the stability of the floated material, the samples containing only coagulants presented values of αa between 4.26 and 5.49, indicating a low stability of the floated material. While the ferric chloride (20mg / L) + FO4550SH (0.5mg / L) and Tanfloc SG (20mg / L) + FO4550SH (1 and 2mg / L) combinations were the ones that produced a floated material with greater stability, 0.35 and α = 0.40, respectively, demonstrating that the use of the polymers provides greater stability of the floated material when it is subjected to turbulence.

La découverte de la supraconductivité à haute température dans les cuprates supraconducteurs en 1986 a révolutionné le secteur et remis en cause la théorie conventionnelle (BCS) de la supraconductivité. Malgré des avancées importantes dans la course aux plus hautes températures critiques, à ce jour, aucune théorie ne fournit une interprétation satisfaisante des propriétés de ces matériaux.L’évolution de la température critique en fonction du taux de strontium dans les solutions solides supraconductrices La2-xSrxCuO4 et La1,6 xNd0,4SrxCuO4 forme un dôme supraconducteur pour 0,05 < x < 0,30. Cependant ce dôme montre une anomalie autour de la teneur x = 0,125, où la température critique est abaissée. Grâce aux technologies de plus en plus performantes, de nouvelles analyses physiques pourraient aider à comprendre la supraconductivité dans les cuprates.Pour cela, des monocristaux d’excellente qualité sont nécessaires. La technique de croissance cristalline par la méthode de fusion de la zone solvante est très adaptée à la synthèse de ce type de matériau à fusion non congruente.Une étude préliminaire sur des céramiques a permis de collecter de nombreuses informations. Une analyse par diffraction des rayons X permet de connaitre l’évolution des structures cristallines et des paramètres de mailles en fonction de la teneur en strontium. Les solutions solides La2-xSrxCuO4 cristallisent dans le système orthorhombique Bmab lorsque x < 0,11 et dans le système quadratique I4/mmm pour x > 0,11. En substituant une partie des ions lanthanes par des ions néodymes, la phase orthorhombique est stabilisée et la transition intervient quand x est proche de 0,19. Les températures critiques de ces composés sont déterminées par l’analyse des propriétés magnétiques réalisées à l’aide d’un magnétomètre à SQUID. Ces dernières sont plus complexes pour les solutions solides La1,6 xNd0,4SrxCuO4 en raison du caractère paramagnétiques des ions Nd3+.Les solides cristallisés présentés dans ce travail ont été élaborés dans un four à concentration de rayonnement avec des vitesses de croissance très lentes (1 mm.h-1). Pour atteindre les compositions visées La1,875Sr0,125CuO4 et La1,475Nd0,4Sr0,125CuO4, il est indispensable d’identifier une composition optimale de la pastille solvante. La qualité cristalline des solides cristallisés est observée par l’intermédiaire d’un microscope à lumière polarisée et par la diffraction des rayons X par la méthode de LAUE. La détermination des paramètres de maille, des températures critiques, des analyses élémentaires par microsonde, couplés aux résultats obtenus sur les céramiques permettent d’obtenir la teneur en cation de ces cristaux. / High critical temperature superconductivity discovery in cuprates superconductors in 1986 revolutionized this sector and questioned the BCS theory. In spite of great improvement in critical temperatures, no theory fully explains the properties of these materials. The critical temperature evolution according to strontium’s content in La2-xSrxCuO4 and La1,6 xNd0,4SrxCuO4 superconductor solid solutions show a superconductive dome for 0,05 < x < 0,30. However, around x = 0,125, there is a magnetic anomaly where the critical temperature decreased. With the help of more efficient technologies, new physical analysis might help to give a better interpretation of the superconductivity in the cuprates materials. Therefore single crystals of great quality are needed. The travelling-solvent floating-zone method is particularly compatible with non-congruent fusion materials as cuprates. First, a preliminary study on polycrystalline samples was conducted and gave interesting information about structure and physical properties. X-rays powder diffraction experiments were used to analyze the crystalline structures and the cell parameters of these materials. The La2-xSrxCuO4 solid solutions crystallize in the orthorhombic Bmab system if x < 0,11, and in the tetragonal I4/mmm system if x > 0,11.With the substitution of Lanthanum ions by Neodymium ions, the orthorhombic phase is stabilized and the transition occurs only for x near 0,19. The critical temperatures of these compounds are extracted from the magnetic properties analysis, obtained by a SQUID magnetometer. These properties are more complicated for the La1,6 xNd0,4SrxCuO4 solid solutions because of the paramagnetic nature of Nd3+ ions. In this work, the crystals are synthesized in an optical furnace with small growth rates (1 mm.h-1). For the selected compositions of La1,875Sr0,125CuO4 and La1,475Nd0,4Sr0,125CuO4, the solvent rod must be optimal. Crystalline quality of the crystals is checked by polarized light microscopy and by the LAUE method. Elemental analysis by electron probe micro analysis and the results of the cell parameters and the critical temperatures, compared with those obtained from the polycrystalline materials are used for the composition determination of these crystals.

Ma thèse présente une analyse du signifiant Europe dans trois corpus allemand, français, britannique. Chaque corpus contient les programmes électoraux européens des partis politiques nationaux qui ont obtenu au moins une fois un siège au Parlement Européen. La période commence aux premières élections européennes en 1979 et se termine avec les élections européennes de 2004.Une analyse lexicométrique du signifiant Europe dans les trois langues révèle de nouvelles perspectives pour la compréhension linguistique de la notion d'Europe dans ces champs politico-discursifs. Elle permet de tirer des conclusions sur les problèmes de communication au niveau européen, sur l'objectif politique de l'Union Européenne et la légitimation du pouvoir de l'UE. Selon notre hypothèse de recherche, une telle légitimation se fonde sur une conception imaginaire de l'identité européenne commune aux différents peuples. Même si le pouvoir politique peut considérer qu'il est légitimé par une telle conception, l'analyse révèle des différences importantes entre les conceptions imaginaires circulant dans les trois champs discursifs comparés.L'analyse lexicométrique est exploitée sur le plan quantitatif mais aussi au niveau qualitatif. A l'échelle quantitative, l'index, les spécificités d'Europe, ses quasi-synonymes et les cooccurrences d'Europe sont analysés et interprétés. L'approche qualitative du contexte du segment thématique répété Europe est...' conduit à des conclusions supplémentaires. L'analyse de ce segment définitoire cherche à rendre visible, dans une démarche pragmatique, le contenu impliqué des différents énoncés. Cela conduit à figurer l'horizon sémantique au sein duquel le signe Europe apparaît. Les positionnements de la notion d'Europe et les argumentations liées à l'expression linguistique dans les trois différents corpus sont comparés dans cette phase de la recherche afin de mettre en évidence l'horizon discursif dans lequel apparaît la notion d'Europe. / My PhD thesis analysis the signifier Europe in three corpora composed of German, French and British texts. Every corpus contains elections manifestos from national political parties that were represented in the European Parliament at least once with one a seat. The study starts with the first European elections 1979 and ends with the European elections of 2004.An analysis with the help of textual statistical measurements reveals new perspectives on the language comprehension of the notion Europe in the three different fields of political discourses. It allows conclusions about communication problems on a European level, about the political objectives of the European Union and about the legitimation of its political power. According to the research hypothesis the legitimation of the political power of the European Union is based on an imagined conception of a common European identity. Even if the political actors claim that they are legitimized by such an identity the study reveals something different. It shows some substantial differences between the imagined conceptions circulating within the three studied fields of political discourses.The textual corpora are explored with quantitative measurements and also with qualitative methods of text analysis. The frequency, the specific use of Europe and its quasi-synonyms, as the collocation of Europe are measured quantitatively. Additional conclusions were drawn from the qualitative analysis of the thematic word unit Europe is'. The analysis of this word unit is based on a pragmatic understanding of sense and tries to bring to evidence the implied content of the different utterances. In doing so, the semantic horizon of the sign Europe can be represented. During this research phase argumentations linked to the linguistic expression Europe are explored in order to analyse the discursive horizon in which the notion is used in the different discourses.

Les systèmes critiques basés sur l’arithmétique flottante exigent un processus rigoureux de vérification et de validation pour augmenter notre confiance en leur sureté et leur fiabilité. Malheureusement, les techniques existentes fournissent souvent une surestimation d’erreurs d’arrondi. Nous citons Arian 5 et le missile Patriot comme fameux exemples de désastres causés par les erreurs de calculs. Ces dernières années, plusieurs techniques concernant la transformation d’expressions arithmétiques pour améliorer la précision numérique ont été proposées. Dans ce travail, nous allons une étape plus loin en transformant automatiquement non seulement des expressions arithmétiques mais des programmes complets contenant des affectations, des structures de contrôle et des fonctions. Nous définissons un ensemble de règles de transformation permettant la génération, sous certaines conditions et en un temps polynômial, des expressions pluslarges en appliquant des calculs formels limités, au sein de plusieurs itérations d’une boucle. Par la suite, ces larges expressions sont re-parenthésées pour trouver la meilleure expression améliorant ainsi la précision numérique des calculs de programmes. Notre approche se base sur les techniques d’analyse statique par interprétation abstraite pour sur-rapprocher les erreurs d’arrondi dans les programmes et au moment de la transformation des expressions. Cette approche est implémenté dans notre outil et des résultats expérimentaux sur des algorithmes numériques classiques et des programmes venant du monde d’embarqués sont présentés. / Critical software based on floating-point arithmetic requires rigorous verification and validation process to improve our confidence in their reliability and their safety. Unfortunately available techniques for this task often provide overestimates of the round-off errors. We can cite Arian 5, Patriot rocket as well-known examples of disasters. These last years, several techniques have been proposed concerning the transformation of arithmetic expressions in order to improve their numerical accuracy and, in this work, we go one step further by automatically transforming larger pieces of code containing assignments, control structures and functions. We define a set of transformation rules allowing the generation, under certain conditions and in polynomial time, of larger expressions by performing limited formal computations, possibly among several iterations of a loop. These larger expressions are better suited to improve, by re-parsing, the numerical accuracy of the program results. We use abstract interpretation based static analysis techniques to over-approximate the round-off errors in programs and during the transformation of expressions. A tool has been implemented and experimental results are presented concerning classical numerical algorithms and algorithms for embedded systems.

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.

Globulettes have recently been found in the Rosette Nebula, the Carina Nebula and other nebulæ. They are expected to be seeds of brown dwarfs and free-floating planetary-mass objects. The size distribution in the Carina Nebula was found to follow a power-law, and the same power-function resulted in 880 +- 250 globulettes in total in the Rosette Nebula. Compared to the 145 observed objects in this nebula, many globulettes are beneath the resolution limit of the Nordic Optical Telescope, which was used to explore the Rosette Nebula. A simulation that arranged all these globulettes randomly in the nebula determined that some globulettes are captured by stars. They are believed to form into one or more planets, orbiting the star thereafter. The possibility that globulettes result into the formation of planets, orbiting a star, is some 4.75·10^2 per cent. According to this simulation, about 3.35·10^3 per cent of the stars with spectral type A to M host one or more planets that once have been globulettes. / <p>Validerat; 20101217 (root)</p>

現今由政府所主導土地開發，常因開發方式的僵固化而造成公平與效率的爭議，本研究的目的即在於尋找另一種新的土地開發方式──浮動開發，希望能有效地解決爭議而達成開發目標，並以南二高交流道特定區開發為例，模擬浮動開發之運作模式，使其能落實應用。 　　本研究首先探討現行國內土地開發方式的優缺點及比較國外彈性土地開發方式之功能目的，期望能從中找適合國內的開發模式。結果本研究採用浮動分區(Floating Zone)為主要依據，配合現實環境，研擬出二階段浮動開發模式及運作流程，並以理性預期理論及獨占理論來說明浮動開發的立論依據，進而探討其特性及限制面，同時與現行土地開發方式作一比較。 　　另外，浮動開發的基礎在於協商的運作，因此本研究從協商的基本意義及目的作探討，並針對土地開發協商，尋找國內外範例來分析其優缺點及運作情形，進而建立二階段二部分之浮動開發的協商模式。 　　在模擬應用浮動開發於交流道特定區時，首先進行交流道特定區的特性分析，並以中山高交流道特定區的開發情形作檢討，而認為其開發成果並不理想，實因受限於土地開發的不合理性，因此南二高新市交流道特定區的開發，採取本研究之浮動開發方式來模擬運作，評選出四處浮動區位來協商開發。 　　為了解專家學者對浮動開發方式之意見，本研究以層級分析法(AHP)來對浮動開發與協商作專家學者的問卷實證。首先對浮動開發及協商之特性與策略作出層級設計，選出三十位專家學者作答，其綜合結果如下： 　　1.浮動開發為較為公平的土地開發方式，而效率也能在整體運作下達到成果。 　　2.協商的運作應是可行且公平的，但效率的達成則較差，而法令制度的建立被視為運作上最重要的依據。 　　綜合以上之分析，本研究之結論及建議如下： 　　1.浮動開發先期作業長，應用上應及早規劃。 　　2.應有一套合理鑑價制度，使權益分配更合理。 　　3.應用於交流道特定區時，建議將交流道與特定區一同規劃浮動。 　　4.為使協商運作順利，應籌組公正的仲裁機構。 　　5.及早培養協商人才，以利協商的進行。 　　6.可建立政府間的協商管道，使中央與地方共享開發成果。 / The land development led by the government often causes the issues of fairness and efficiency by inflexible development methods. The purpose of this thesis is to propose a new land development approach-floating development-to effectively solve the problems and achieve the goal of land development. This thesis takes the special district areas of the South Second Highway Interchange as examples to study the feasible of floating development. 　　First, this thesis considers the pros and cons of the domestic land development methods and compares with the function and goal of foreign flexible land development methods. Moreover, according to the Floating Zoning and the current environment, this thesis offers a two-stage floating development and an operating process, explains the floating development mode by monopoly theory and rational expectation theory, examines its characteristic and limitation, and compares with current land development methods. 　　In addition, the floating development approach bases on negotiation, therefore, this thesis examines the definition and the aim of negotiation. Moreover, this thesis focuses on land developing negotiation to analyze its pros and cons and operation and to build the negotiating mode of a two-stage floating development approach. 　　Applying the floating development to the interchange special district area, this thesis first analyzes the characteristics of the interchange special district areas of the Chug-Shane Highway, and finds that it is not successful resulted from the irrational land development. Therefore, this thesis takes Shin-Shih interchange special district area of the South Second Highway for example to examine the floating development method and to screen out four floating locations for development and negotiation. 　　In order to study the experts' and scholars' opinions on floating development method, this thesis adopts the AHP (Analysis Hierarchy Process) to survey the floating development and negotiation. This thesis designs goals and strategies of floating development and negotiation, and selects 30 experts and scholars to answer an AHP questionnaire. The results are as follows: 　　1.The floating development is fair and more effective. 　　2.The operation of negotiation is workable and fair, however, is lack of efficiency. Establishing disagrees and regulations is regarded as the most important reference of operation. 　　According to the above analyses, this thesis concludes and suggests: 　　1.It takes long time to prepare the floating development, therefore, it should be designed and planned earlier before applying. 　　2.We should develop a reasonable evaluating system to make the distribution of benefits more reasonable. 　　3.When applying floating development to the interchange special district area, it would be better to plan floating interchanges and floating special district areas together. 　　4.To operate negotiation fluently, establishing appropriate arbitration institution is suggested. 　　5.Cultivating professional negotiators earlier will be helpful to negotiation process. 　　6.Building the negotiation channel among governments will benefit both central and local governments.

本文主要嘗試引進泡沫於匯率目標區中，藉由調整政府政策來避免含泡沫 之匯率路徑，不符合匯率目標區之限制。最後分別比較匯率目標區與浮動 匯率兩制度的匯率變異性。