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Prédiction des performances thermo-aérauliques des bâtiments par association de modèles de différents niveaux de finesse au sein d'un environnement orienté objetMora, Laurent 19 September 2003 (has links) (PDF)
La conception de systèmes énergétiques innovants et la caractérisation du confort des occupants requièrent de d'être capable d'estimer les détails des écoulements et des transferts de chaleur au sein des zones des bâtiments. Les méthodes de modélisation permettant d'estimer ces détails, telles que les méthodes zonales et CFD, sont difficilement applicables à l'étude d'un bâtiment dans son ensemble et sur de longues périodes de temps. Notre étude consiste à proposer une plate-forme de simulation permettant dans un premier temps de traiter la plupart des zones du bâtiment et de son enveloppe à l'aide de l'approche nodale qui considère chacune des zones comme un volume parfaitement uniforme. Chaque zone est alors caractérisée par un seul noeud de calcul où sont déterminées les variables d'états (température, pression, concentration, etc.). Ensuite, il s'agit d'étudier les détails au sein d'un nombre limité de zones et d'estimer l'impact de ces détails sur le comportement global du bâtiment. Ainsi, nous proposons différentes méthodes de couplage entre d'une part la méthode nodale et d'autre part, les méthodes zonales et CFD. Après avoir présenté les différentes méthodes de modélisation retenues pour la détermination des transferts de masse et de chaleur dans les bâtiments, nous tentons de montrer l'intérêt d'utiliser l'une plutôt qu'une autre en fonction, des spécificités de chacune des zones, et de l'étude à effectuer. Ensuite, nous exposons la plate-forme de simulation développée, permettant de mettre en oeuvre aussi bien les approches nodales et zonales, que les différentes procédures de couplage dépendant du type d'association de modèles. Enfin, différentes applications viennent confirmer les capacités offertes par la plate-forme, pour moduler le niveau de finesse des modèles utilisés pour représenter chacune des zones d'un bâtiment, mais aussi pour proposer de nouvelles orientations de recherche. En effet, la dernière application présente une approche de couplage entre les approches zonale et CFD, dans laquelle la première tire la connaissance de la structure de l'écoulement de la seconde. L'outil développé apporte de nombreuses possibilités d'applications, aussi bien pour la caractérisation du bâtiment lui-même que de son intégration dans son environnement immédiat.
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Génération automatique de modèles zonaux pour l'étude du comportement thermo-aéraulique des bâtimentsMusy, Marjorie 08 July 1999 (has links) (PDF)
Cette étude a pour objet de montrer qu'il est possible de générer automatiquement des modèles zonaux pour l'étude du comportement thermique et aéraulique des bâtiments. Les modèles zonaux sont basés sur le partitionnement des pièces en un petit nombre de sous-volumes. Cette approche est intermédiaire entre celle des modèles à un noeud (qui considèrent que la température est homogène dans chaque pièce, et pour cette raison ne permettent pas de prédire le confort thermique dans une pièce) et celle des codes CFD (qui sont très coûteux en temps de calcul). Pour atteindre notre objectif, nous avons reformulé le modèle zonal. Ceci a consisté à regrouper les équations de description du comportement du bâtiment dans des sous-systèmes d'équations. Ce regroupement est calqué sur le découpage spatial des pièces. Ainsi, les équations de bilan et d'état appliquées à un sous-volumes forment les modules de la famille des « cellules » et celles de transfert entre deux sous-volumes forment les modules de la famille des « interfaces ». Ces familles sont constituées de plusieurs modèles correspondant aux différents types d'écoulement qui se développent dans les bâtiments. Ceux-ci ont été traduits en objets SPARK, lesquels forment la bibliothèque de modèles. Construire une simulation consiste à choisir les modèles appropriés pour décrire les pièces et à les connecter. Cette dernière étape a été automatisée, si bien qu'il ne reste plus à l'utilisateur qu'à donner le partitionnement et à choisir les modèles qu'il désire implémenter. Le système d'équations résultant est résolu par le solveur de SPARK. Des résultats de simulations pour différentes configurations d'écoulement dans des pièces sont présentés et comparés à des données expérimentales. Nous donnons également des exemples d'application de la méthode zonale à l'étude d'un groupe de deux pièces, d'un bâtiment et d'une pièce de géométrie complexe.
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Improved Experimental Agreement of Ionization and Pressure Peak Location by Adding a Dynamical NO-Model / Förbättrad experimentell överenstämmelse med jonström- och trycktoppsläge genom införande av en dynamisk NO-modellClaesson, Daniel January 2004 (has links)
<p>Modelling combustion engines is an important tool in engine research. Development and modelling of ionization current has potential in developing virtual pressure sensors based on ionization measurements. Previous models has problem when predicting the true relationshipbetween the pressure peak location and ionization peak location, and both too early and too late predictions has been observed. An explanation for these discrepancies are provided and a model where the experimental mismatch has been reduced to less than one CAD is also presented. This is well within the measurement uncertainty.</p>
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Improved Experimental Agreement of Ionization and Pressure Peak Location by Adding a Dynamical NO-Model / Förbättrad experimentell överenstämmelse med jonström- och trycktoppsläge genom införande av en dynamisk NO-modellClaesson, Daniel January 2004 (has links)
Modelling combustion engines is an important tool in engine research. Development and modelling of ionization current has potential in developing virtual pressure sensors based on ionization measurements. Previous models has problem when predicting the true relationshipbetween the pressure peak location and ionization peak location, and both too early and too late predictions has been observed. An explanation for these discrepancies are provided and a model where the experimental mismatch has been reduced to less than one CAD is also presented. This is well within the measurement uncertainty.
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NUMERICAL SIMULATIONS OF ATMOSPHERIC DYNAMICS ON THE GIANT PLANETSLian, Yuan January 2009 (has links)
The giant planets exhibit banded zonal jet streams that have maintained theirstructures over decades. There are long-standing questions: how deep the windstructures extend? What mechanisms generate and maintain the observed winds?Why are the wind structures so stable? To answer these questions, we performedthree-dimensional numerical simulations of the atmospheric flow using the primitiveequations.First, we use a simple Newtonian cooling scheme as a crude approach to gener-ate atmospheric latitudinal temperature differences that could be caused by latentheating or radiation. Our Jupiter-like simulations show that shallow thermal forcingconfined to pressures near the cloud tops can produce deep zonal winds from thetropopause all the way down to the bottom of the simulated atmosphere (a fewhundred bars). These deep winds can attain speeds comparable to the zonal jetspeeds within the shallow, forced layer; they are pumped by Coriolis accelerationacting on a deep meridional circulation driven by the shallow-layer eddies.Next, we explicitly include the transport of water vapor and allow condensationand latent heating to occur whenever the water vapor is supersaturated. Our simu-lations show that large-scale moist convection associated with condensation of watervapor can produce multiple zonal jets similar to those on the gas giants (Jupiterand Saturn) and ice giants (Uranus and Neptune). For plausible water abundances(3-5 times solar on Jupiter/Saturn and 30 times solar on Uranus/Neptune), oursimulations produce about 20 zonal jets for Jupiter and Saturn and 3 zonal jetson Uranus and Neptune. Moreover, these Jupiter/Saturn cases produce equatorialsuperrotation whereas the Uranus/Neptune cases produce equatorial subrotation,consistent with the observed equatorial jet direction on these planets. Sensitiv-ity tests show that the water abundance is the controlling factor; modest waterabundances favor equatorial superrotation, whereas large water abundances favorequatorial subrotation. This provides a possible mechanism for the existence ofequatorial superrotation on Jupiter and Saturn and the lack of superrotation onUranus and Neptune.
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Use of Finite-element Analysis to Improve Well Cementing in HTHP ConditionsArias, Henry 16 December 2013 (has links)
Oil companies need to evaluate the risk of annular fluid or gas migration if cement fails during the life of the well. Sustained casing pressure can lead to shutting in the wells to avoid health, safety, and environment (HSE) risks and government fines. To understand the long-term integrity of cement in high temperature and high pressure (HTHP) conditions and the mechanical properties that affect the ability of cements to seal fluids, this project used finite-element models (FEMs) to study the stress-causing phenomena. FEM analyses in ABAQUS version 6.11 were used to determine the potential of cement failure in oil wells. The model uses a 3D section of a well that can be used for different casing and formation types under different loading conditions.
The model built in ABAQUS version 6.11 allows incorporating materials with nonlinear mechanical properties; it also uses FEM analysis to forecast fractures inside the cement under different loading scenarios like hydraulic fracture jobs or casing tests. The finite-element model included cases for cement cracking, cement debonding, and plastic deformation of the cement and rock that can generate loss of zonal isolation. Linear manner: set cements behave elastically until a failure criterion is reached, and then they can behave plastically. The FEM approach can reproduce stresses, strains, and volume changes in the material under different environmental HTHP conditions.
Cemented wells have both tensile and compressive stresses that make some parts of the cement sheath experience fracture initiation, plastic deformation, or debonding. This dissertation provides a model that will help drillers design the set cement for long-term integrity in HPHT well conditions. The FEM predicts if the cement sheath can develop debonding, cracks or plastic deformations during the life of the well. The cement sheath needs to be designed for long-term zonal isolation to avoid interzonal communications, remedial costs and environmental problems related to cement seal.
A CMS™-300 Automated Permeameter, a mechanical properties analyzer, HPHT cement consistometer, annular expansion molds, and tri-axial test equipment were used in this study to test cements for specific applications in three Colombian oil fields, including an oil field with in-situ combustion project.
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Modélisation de la demande énergétique des bâtiments à l'échelle d'un quartierGros, Adrien 26 June 2013 (has links) (PDF)
Depuis 2007, plus de la moitié de la population mondiale vit en ville. La forte densité de population et d'activité entraîne une augmentation des besoins en climatisation des bâtiments en été. L'augmentation des températures due à l'effet d'îlot de chaleur urbain est principalement liée à l'aménagement urbain et aux flux de chaleurs anthropiques causés par l'utilisation des systèmes de chauffage et de climatisation. En agissant sur l'aménagement urbain, comme la densité de construction, l'albédo de surface ou les espaces verts, le microclimat urbain peut être amélioré ; ce qui permet ainsi de réduire les besoins énergétiques des bâtiments. Nous proposons dans ce manuscrit un modèle pour calculer les besoins énergétiques des bâtiments à l'échelle d'un quartier en prenant en compte l'interaction entre le microclimat urbain et les bâtiments. L'objectif est de décrire d'une part les ambiances intérieures du bâtiment, telles qu'elles sont modélisées dans les codes de thermique dynamique du bâtiment, et d'autre part, l'environnement extérieur tel qu'il est modélisé dans les codes de micro-météorologie. Pour travailler à cette échelle,la description détaillée de tous les transferts thermiques à l'intérieur et à l'extérieur de chaque bâtiment n'est pas appropriée. Ainsi, un modèle réduit de bâtiment est couplé avec un modèle simplifié de microclimat urbain. Le modèle de bâtiment est basé sur la méthode des facteurs de pondération et permet de prendre en compte les gains internes, l'inertie de l'enveloppe et les échanges radiatifs et convectifs à l'intérieur du bâtiment. Il est couplé à un modèle radiatif en milieu urbain, basé sur la méthode des radiosités, et un modèle zonal tridimensionnel de la canopée urbaine. Après avoir présenté ces modèles, ils sont appliqués sur un cas d'application, à savoir le quartier Pin Sec de la ville de Nantes. Différents scénarios d'aménagement urbain sont simulés sur une année afin d'analyser l'influence de l'aménagement urbain sur les besoins énergétiques des bâtiments.
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A fusão zonal horizontal aplicada ao crescimento de policristais grosseiros de alumínioKlein, Cândida Cristina January 2009 (has links)
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.
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Reconstrução dos paleoventos do Gonduana no Juro-cretáceoMello, Raquel Gewehr de January 2018 (has links)
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.
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A fusão zonal horizontal aplicada ao crescimento de policristais grosseiros de alumínioKlein, Cândida Cristina January 2009 (has links)
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.
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