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ABSTRACT In the first part of this study, a determinist mathematical approach is used to describe any kind of pollutant migration in groundwater. This theoretical background is focused on the miscible displacement and the particularities of the multiporous media are discussed. Subsequently, an objective numerical tool is developed to solve the convection-dispersion equations including immobile water effect, degradation, and adsoption. Among all the available techniques, two finite element methods in fixed meshing grids have been programmed: -the F.U.P.G. method (Full Upwind Petrov Galerkin), using a space-time upwinded weighting function with optimized coefficients, -the H.E.L.M. method (Hybrid Eulerian Lagrangian Method), using the eulerian lagrangian approach with reverse node tracking. Those two schemes are tested on a large number of reference problems. The model have been applied to study the behaviour of solutes (nitrates mainly) in the cretaceous chalk of the Hesbaye area (Belgium). Experimentations have been performed on domains of increasing size (laboratory tests, in situ tracer tests). For each interpretation, the particularities of the context have been taken into account, and miscible transport coefficients have been objectively determined. Hence, the medium is well characterized and the scale effect is quantified. This leads to previsional applications. RESUME Ce travail débute par le développement dun formalisme mathématique déterministe pour décrire, en toute généralité, la propagation de polluants dans les eaux souterraines. Cette étude théorique permet de situer le problème posé (pollution miscible diluée) dans un cadre plus large, et de souligner les particularités dun milieu à porosité multiple. Dans un second temps, un outil numérique objectif est mis au point pour résoudre les équations de convection-dispersion avec effet deau immobile, dégradation, et adsorption. Parmi le grand nombre des procédés existants, deux méthodes par éléments finis en maillage fixe ont été programmées : -la méthode F.U.P.G. (Full Upwind Petrov Galerkin) basée sur un décentrage des fonctions de pondération, optimum dans le temps et lespace, -la méthode H.E.L.M. (Hybrid Eulerian Lagrangian Method) utilisant un processus eulerien lagrangian avec traçage inverse des positions nodales. Les deux schémas sont testés sur de nombreux problèmes de référence. Ensuite, ce modèle est appliqué à des situations pratiques pour étudier le comportement de solutés (nitrates notamment) dans laquifère crayeux du Crétacé de Hesbaye (Belgique). Des domaines de taille croissante sont étudiés (essais de laboratoire, traçage in situ). A chaque étape, les coefficients de transport miscible sont déterminés de façon objective, en tenant compte de la spécificité des tests. Ainsi, leffet déchelle peut être quantifié et il est possible denvisager des scénarios prévisionnels.

Une demande mondiale grandissante en gaz naturel pousse à exploiter des ressources de plus en plus acides (concentration des gaz acides pouvant atteindre 20% en volume). Le procédé de traitement de gaz par des solutions d'amines, existant depuis plus de 50 ans, est le plus répandu pour éliminer les composants acides (CO2, H2S, mercaptans…). Ce procédé comporte deux unités principales : une colonne d'absorption gaz liquide à contre-courant pour la séparation des composants acides du gaz et une colonne de régénération du solvant chargé. On recherche une optimisation du design, en particulier de l'absorbeur, en vue de réduire les couts et d'augmenter l'efficacité. Dans la colonne d'absorption, le transfert de matière s'avère limitant par rapport à la thermodynamique. Ainsi l'optimisation du design de cette unité passe par une maitrise des paramètres hydrodynamiques et de transfert des contacteurs utilisés dans les colonnes. Plusieurs études existantes sur unités pilotes proposent des corrélations majoritairement empiriques pour les paramètres critiques de dimensionnement. Par ailleurs leur extrapolation à l'échelle industrielle montre une divergence importante entre les différentes corrélations. Une meilleure compréhension des phénomènes physiques ainsi qu'une identification des paramètres importants pour l'extrapolation est donc requise. Dans ce contexte, la présente thèse a comme objectif principal la compréhension de l'effet de changement d'échelle sur les paramètres hydrodynamiques et l'aire interfaciale d'échange dans le cas des plateaux à clapets. La méthodologie employée dans cette étude se base sur une complémentarité entre une étude expérimentale et le potentiel offert par les outils de simulation numérique. L'étude expérimentale s'est effectuée sur deux colonnes pilotes rectangulaires transparentes ayant deux longueurs de passe différentes. Des mesures de pertes de charge, de hauteur de l'émulsion, de rétention liquide et d'aire interfaciale d'échange ont été réalisées. Des mesures innovantes de profils de l'émulsion gaz-liquide sur un plateau sont également présentées. Les différents résultats expérimentaux ont permis la proposition d'un diagramme hydrodynamique ainsi qu'une compréhension et une analyse phénoménologique cohérente de l'écoulement sur une large gamme de vitesses liquide et gaz. La comparaison entre les deux colonnes a permis, en premier lieu, l'identification des vitesses liquide et gaz pertinentes pour l'extrapolation. Des similitudes de comportement ont été trouvées pour certains paramètres (rétention liquide moyenne, perte de charge clapets, aire interfaciale) offrant ainsi la possibilité de proposer des corrélations basées sur une description phénoménologique dépendant essentiellement de deux nombres adimensionnels que sont le nombre de Froude (comparant l’inertie gaz au poids liquide sur le plateau) et le paramètre de l’écoulement (comparant les deux inerties liquide et gaz). En revanche une influence notable de la longueur de passe est relevée. En particulier des profils de l'émulsion nettement différents entre la petite et la grande colonne ont été observés. Des risques d'extrapolation sont par conséquent pointés dans cette thèse notamment pour des paramètres tels que la hauteur de liquide clair ou la hauteur moyenne de l’émulsion. Dans une deuxième partie, l'intérêt a été porté sur la simulation numérique des écoulements sur les plateaux. L'importance et la complexité de la modélisation du terme d'interaction entre les deux phases sont soulignées. Une approche proposée dans la littérature a été testée et montre la possibilité de l'emploi des simulations CFD comme outil pour une meilleure compréhension des comportements locaux. En outre une approche de modélisation nouvelle est proposée dans une optique de valorisation des outils numériques pour l'extrapolation. / The increasing demand of natural gas has encouraged the exploration of sour ressources (concentration of acid gases (CO2, H2S, mercaptans…) reaching 20% of volume). The most popular gas sweetening process which uses amine solutions has been in use for over 50 years. This process consists of two main units: a counter current gas-liquid absorption column in which acid compounds are removed from the gas and a stripper column for loaded solvent regeneration. An optimisation is needed to reduce the over-sizing costs and enhance efficiency especially for the absorber column. For the absorption column the mass transfer is the limiting phenomenon in comparison to thermodynamics. Thus design optimisation of such units needs full knowledge of both hydrodynamic and mass transfer parameters of the contactors used in the absorbers. Several literature studies carried out on pilot units propose empirical correlations for these critical design parameters. However the extrapolation to industrial scale shows important divergences between existing correlations. It seems that a better understanding of physical phenomena as well as an identification of the key parameters for extrapolation is still needed. Under this context, the present work aims at understanding the scale effect on hydrodynamics and interfacial area on valve trays contactors. The methodology employed relies on the complementarity between experimental studies and the potential offered by numerical simulation tools. The experimental study has been carried out on two rectangular and transparent pilot columns having two different path lengths. Measurements of pressure drops, liquid retention, emulsion height and interfacial area along with innovating measurements of emulsion profiles have been made. Experimental results allowed the establishment of a hydrodynamic diagram as well as the understanding and the phenomenological analysis of the two phase flow over a large scope of gas and liquid velocities. Comparison between the two columns led, at first, to identifying pertinent liquid and gas velocities for extrapolation. Similarities between both columns were noticed for some parameters (liquid retention, valve pressure drop and interfacial area) allowing the proposition of correlations based on phenomenological description of the flow. These correlations involve mainly two non-dimensional numbers which are Froude number (comparing the gas inertia to liquid weight on the tray) and flow parameter (comparing liquid inertia to gas inertia). However an effect of path length has been observed in particular for emulsion profiles. Risks for extrapolation related to this effect have been consequently pointed out for some parameters such as clear liquid height or mean emulsion height. In a second part of the study, the interest was focused on numerical simulation of tray hydrodynamics. Importance and complexity of gas liquid interaction term modelling have been highlighted. Using a proposed approach in literature, CFD simulations with the Eulerian model under the software Ansys Fluent have been made. They proved the possibility of using numerical simulation as a mean for a better understanding of the two phase flow local behaviour. Moreover a new approach is proposed which could be used in order to make numerical tools more valuable for extrapolation.

Made available in DSpace on 2014-07-29T14:49:10Z (GMT). No. of bitstreams: 1 Heloisio_Caetano.pdf: 4628443 bytes, checksum: b488772923cf9872b1b42391f8d89610 (MD5) Previous issue date: 2011-08-08 / The analyses of the dynamics of the crops composition in the State of Goiás was first started by Yokoyama (1988). Here, is made a continuity of this work and methodology enlargement elements like maps and graphics to better scrutinize the phenomenon throw the use of shift-share rates. Further socio economic inferences are based in agricultural frontier´s theory. The mathematical methods and uses, of the shift-share rates, are discussed. Using this model, the area effects are decomposed into scale and substitution effects, and it shows the geographic location effects for the selected microrregiões, and for this also the production effects. The agricultural frontier model is presented in basics ideas. The indices are presented for individual and the set of crops in the microrregiões and so are fluctuation of production of the set and location of crops in the State of Goiás. The results point changes in the crops composition in the State of Goiás. Staple food production in the new context, despite changes of territory of crops, it maintains important role in National context. It presents results about the important discussion that involves sugar-cane expansion, relations to soy-beans and cattle and conclusions about crop relations to ´cerrados´ area. The crop period goes is from 1990 to 2009. / A análise da composição das culturas no Estado de Goiás foi um trabalho iniciado por Yokoyama (1988). Neste realiza-se uma continuação aliada a uma atualização metodológica ao utilizar elementos como mapas e gráficos que permitiram uma visão mais ampla dos fenômenos evidenciados pelos índices Shift-Share. Neste trabalho também ocorre uma renovação da análise, onde o conceito de fronteiras agrícolas fundamenta o estudo da ação dos sujeitos. Pelo modelo decompõe-se o efeito área em efeito escala e substituição, e apresenta também o efeito localização geográfica, apresentando estes índices também em porcentagem, para as culturas selecionadas. Os efeitos são apresentados também para as microrregiões selecionadas, sendo que para estas foi possível discutir o efeito composição do produto. O modelo de fronteiras agrícolas é apresentado em suas idéias fundamentais. São apresentadas as análises a partir do cálculo dos índices, para as culturas e conjunto de lavouras, e a localização das culturas no Estado. Os resultados apontam para ocorrências na produção de alimentos frente a este novo panorama, onde apesar de o Estado sofrer consideráveis alterações na área plantada destas culturas a sua importância mantém-se no contexto nacional. Apresenta dados e resultados sobre a discussão que envolve expansão da cana-de-açúcar, relações com a soja e o gado e conclusão sobre as relação entre as culturas e as áreas de cerrado. O período analisado foi 1990 a 2009.

Made available in DSpace on 2014-07-29T15:18:19Z (GMT). No. of bitstreams: 1 Dissertacao part 1 Pedro Joao Barbosa Junqueira.pdf: 6538524 bytes, checksum: 082d6c8def54f284189ca0be0080c827 (MD5) Previous issue date: 2010-08-31 / The dam construction tecnology with roller compacted concrete has undergone noticeable improvements in the areas of concrete technology and enforcement procedure. One can cite the enrichment of roller compacted concrete dam face and the whole sequence leading to obtaining such enrichment, in a short-term enforcement, by the least cost and with the guarantee of the security needed, as one of those remarkable improvements. This work, however, tries to contribute with the theme of the properties of concrete and incorporates basic issues of materials science to set a failure criterion to the results of combined loadings tests performed in RCC specimens of varied sizes, made with the same dosage of Junqueira et al. (2008). The goal is to predict the real strength of the roller compacted concrete dam. Therefore, tests of diametral compression, uniaxial compression, triaxial compression and direct shear tests were performed in RCC specimens of different sizes. The results of such tests were presented using tables and graphs which showed a fall of resistance with increasing the size of the specimen tested face of such loadings. Finally, the data from all trials of this work and of Junqueira et al. (2008) were gathered and studied, so as to increase the precision of the strength envelope of Hoek and Brown set. / A tecnologia de construção de barragens com Concreto Compactado com Rolo tem passado por melhorias notáveis nas áreas de tecnologia do concreto e do procedimento executivo. Pode-se citar o enriquecimento do concreto compactado com rolo de face de barragens e toda a seqüência que leva à obtenção de tal enriquecimento, a um curto prazo executivo, pelo menor custo e com a garantia da segurança necessária, como uma dessas notáveis melhorias. O presente trabalho, no entanto, tenta contribuir com o tema das propriedades do concreto e retoma questões básicas da ciência dos materiais para ajustar um critério de ruptura aos resultados de ensaios sob carregamentos combinados realizados em corpos de prova de Concreto Compactado com Rolo (CCR) de dimensões variadas, feitos de dosagem semelhante à usada no trabalho de Junqueira et al. (2008). O objetivo é tentar prever a resistência real apresentada pelo CCR no interior do corpo de uma barragem. Para tanto, foram realizados ensaios de tração na compressão diametral, compressão simples, compressão triaxial e de cisalhamento direto em corpos-de-prova de CCR de dimensões variadas. Os resultados de tais ensaios foram apresentados por meio de tabelas e gráficos os quais mostraram uma queda de resistência com o aumento das dimensões dos corpos de prova ensaiados frente a tais carregamentos. Por fim, os dados de todos os ensaios realizados durante a presente pesquisa e durante a pesquisa de Junqueira et al. (2008) foram agrupados e estudados, a fim de se aumentar a precisão do ajuste da envoltória de resistência de Hoek e Brown.

Master‘s thesis reviews the characteristics of the AVR32 architecture, AVR32UC microarchitecture, and especially AT32UC3A0512 microcontroller. This microcontroller is mounted on the board EVK1100, which is used for debugging applications. The entire analysis is focused on the ability to process audio signals on this board. For the board is created AD/DA interface and its control library. Follows necessary description of used DSP-lib library. The last part is a description of the theory and implementation of two sound effects and implementation of operating system FreeRTOS.