Dans certaines conditions de température et de débit, l’eau naturellement présente dans le kérosène va givrer l’intérieur des conduites du système carburant avion. Ces dépôts peuvent libérer des particules de glace qui sont entrainées par l’écoulement, et provoquent le colmatage des équipements hydrauliques situés en aval. Ce phénomène fut mis en évidence suite à l’accident d’un Boeing 777 en 2008, aussi sa compréhension est un enjeu important pour les acteurs de l’industrie aéronautique. Un dispositif a été spécialement conçu pour reproduire cette menace de façon quantifiée. De l’eau est atomisée dans un écoulement à basse température, puis cristallise pour former une suspension qui vient colmater différentes cibles perforées. Les températures, débits et pertes de charge sont mesurées, et le phénomène est filmé par une caméra haute fréquence. Un modèle a été réalisé à partir de cesobservations, complétées par des données issues de la littérature et de retoursd’expérience. Pour la phase fluide, les équations de Navier-Stokes incompressibles sont résolues par une approche volumes finis. Le couplage pression-vitesse est obtenu par l’algorithme SIMPLE et l’ordre élevé au moyen de la méthode MLS. La phase solide est simulée par éléments discrets. L’interaction fluide-particules repose sur une approche de type milieu poreux. Un code CFD-DEM parallèle a été développé, et les premières simulations d’écoulement en milieu granulaire sont en bon agrément avec des résultats expérimentaux. / Water, which exists naturally in jet-engine fuel, may freeze within theaircraft fuel pipes under certain temperatures and flow rates. The ice particles released by these deposits are entrained by the flow, and clog the hydraulics downstream. The understanding of this phenomenon, highlighted by the crash of a Boeing 777 in 2008, is an important issue for the aviation industry. Therefore a device has been designed to reproduce this threat in a controlled and quantified way. Water is atomized in low temperature jet-engine fuel and the droplets crystallize. The resulting slurry clogs different kinds of perforated targets. Temperatures, flow rates and pressure drops are monitored, and the phenomenon is filmed by a high frequency camera. A model was constructed based on these observations and data from literature and feedbacks. For the fluid phase, the incompressible Navier-Stokes equations are solved within a finite volume framework. The pressure-velocity coupling is achieved using the SIMPLE algorithm and high order of accuracy thanks to the MLS method. The solid phase is simulated using discrete elements. The fluid-particle interaction is based on a porous medium approach. A CFD-DEM parallel code has been developed to run the model. The first simulations of flow through granular media are in good agreement with experimental results.

Este trabalho discute a questão da interação entre o casco do navio e o propulsor em funcionamento conjunto, e sua simulação por ferramentas computacionais. O texto se concentra em descrever os principais efeitos dessa interação, as principais dificuldades em se estimar esses efeitos, os métodos tradicionalmente usados, e como ferramentas computacionais podem ser aplicadas de maneira vantajosa. No texto também pode ser encontrada uma análise crítica dos métodos mais comuns e dos resultados, baseada em trabalhos de diversos autores, publicados nacional e internacionalmente. É apresentado o método dos volumes finitos, usado nesta pesquisa, algumas de suas particularidades principais, vantagens e desvantagens, e os resultados das simulações realizadas, interpretados à luz dos valores experimentais usados para comparação e das limitações do método dos Volumes Finitos. A comparação é feita analisando-se grandezas integrais, como a resistência do casco ou o empuxo do propulsor; e também as características do escoamento, como o perfil de velocidade na esteira, presença de vórtices, e outras estruturas típicas. Os resultados obtidos têm a mesma ordem de precisão dos que tem sido obtidos por outros pesquisadores, internacionalmente, e são coerentes qualitativamente; mas algumas questões referentes aos modelos físico e numérico escolhidos ainda limitam a precisão dos resultados e restringem sua adoção em atividades de engenharia. Entretanto, diversas características observadas no escoamento contribuem para aumentar o conhecimento de alguns fenômenos envolvidos no problema. / This work is about the hull and propeller interaction in joint functioning, and its simulation by computational tools. The text concentrates in describing the main effects of such interaction, the main difficulties in the estimation of these effects, the methods traditionally adopted, and how computational tools can be applied in advantageous way. A critical analysis of the most common methods and results, based on paperworks of several different authors worldwide, can also be found. The Finite Volumes method, used in this research, is presented - its main issues, advantages and disadvantages, and the simulations outcomes, compared to the experimental values and explained by the knowledge of the Finite Volumes method limitations. The comparison is made by means of both integral values, such as the hull\'s resistance or the propeller thrust; as well as the characteristics of the flow, like the wake velocity profile, presence of vortex, and other typical structures. The results shows the same error band than the ones which has been obtained by other researchers, worldwide, and most of the typical characteristics of the flow were observed. But some issues concerned to the chosen physical and numerical models still limit the precision of the outcomes, and restrict the application of such models at engineering activities. But several insights about the flow, obtained at this study, can be useful to the understanding of some phenomena involved in the propeller operation.

Made available in DSpace on 2015-03-05T17:04:36Z (GMT). No. of bitstreams: 0 Previous issue date: 19 / Nenhuma / Com o crescente nível de competitividade no mercado globalizado o planejamento estratégico e seus desmembramentos como o planejamento de produção e a busca de otimizações dos recursos produtivos disponíveis em uma empresa são um dos principais objetivos dos gestores. Para este planejamento é necessário prever as futuras necessidades do mercado, que no ambiente de negócio atual tem mudanças constantes e cada vez mais rápidas. Uma correta orientação aumentará as chances de obter bom resultado que contribuirá para o crescimento da organização (GOERGOFF, 1986). Esta dissertação apresenta um método tentativo para previsão de volumes que se iniciam através da montagem de um mapa sistêmico onde as variáveis são interligadas, depois estas são avaliadas através da análise de correlação e criando equações de regressão é criado um modelo computacional. Estas simulações foram validadas estatisticamente em relação ao histórico e foram elaborados cenários futuros, com possíveis comportamentos para as variáveis de entrad / With the increasing level of competitive in the world market the strategic planning and your dismemberment as production planning and the search of the optimizations of productive resources are are one of the main goals of managers. For this planning is necessary to foresee the future needs of the market, which in the current business environment of constant change and is increasingly rapid. A correct orientation will increase the chances of obtaining good results will contribute to the growth of the organization (GOERGOFF, 1986). This dissertation presents a method to tentative estimates of volumes that starts by the assembly of a map system where the variables are linked, then they are evaluated by analysis of correlation and regression equations of creating a computer model is created. These simulations were validated statistically in relation to historical and future scenarios were developed, with possible behavior for the input variables, generating as a result of the viewing volume of Brazilian exports

[pt] A restituição de modelos tridimensionais complexos de engenharia tem sido um desafio para a computação gráfica desde seus primórdios, pois modelos detalhados são freqüentemente compostos de milhões de polígonos, enquanto as estações gráficas atuais são capazes de exibir, em taxas interativas, apenas algo da ordem de dezenas ou centenas de milhares de polígonos. Uma das formas de melhorar o desempenho de visualizadores de modelos tridimensionais é reduzir o número de polígonos passados para a cadeia de restituição, eliminando grandes grupos de polígonos determinados como não visíveis por estarem fora do volume de visão ou escondidos por outros polígonos. Neste trabalho, realizamos um estudo do uso de volumes envolventes para determinar os conjuntos de polígonos que são potencialmente visíveis, propomos uma forma de estruturar esses polígonos numa hierarquia de forma a diminuir os cálculos necessários para esse fim e compilamos uma série de resultados que permitem nortear o uso de volumes envolventes e a estruturação de modelos. / [en] Rendering complex three-dimensional Engineering models has been a challenge for Computer Graphics ever since its origin, as detailed models are often composed of millions of polygons while current graphic stations are able to display, at interactive rates, only dozens or hundreds of thousands of polygons. A way to increase the performance of viewers of three-dimensional models is to reduce the number of polygons passed to the rendering pipeline by eliminating large groups of polygons classified as non-visible for being out of the viewing frustum or hidden by other polygons. In this work, we study the use of bounding volumes to determine sets of polygons which are potentially visible, propose a way to structure such polygons in a hierarchy so as to restrict the necessary computations for this purpose, and compile a series of results which allow us to take some conclusions on the use of bounding volumes and model structuring.

Este trabalho discute a questão da interação entre o casco do navio e o propulsor em funcionamento conjunto, e sua simulação por ferramentas computacionais. O texto se concentra em descrever os principais efeitos dessa interação, as principais dificuldades em se estimar esses efeitos, os métodos tradicionalmente usados, e como ferramentas computacionais podem ser aplicadas de maneira vantajosa. No texto também pode ser encontrada uma análise crítica dos métodos mais comuns e dos resultados, baseada em trabalhos de diversos autores, publicados nacional e internacionalmente. É apresentado o método dos volumes finitos, usado nesta pesquisa, algumas de suas particularidades principais, vantagens e desvantagens, e os resultados das simulações realizadas, interpretados à luz dos valores experimentais usados para comparação e das limitações do método dos Volumes Finitos. A comparação é feita analisando-se grandezas integrais, como a resistência do casco ou o empuxo do propulsor; e também as características do escoamento, como o perfil de velocidade na esteira, presença de vórtices, e outras estruturas típicas. Os resultados obtidos têm a mesma ordem de precisão dos que tem sido obtidos por outros pesquisadores, internacionalmente, e são coerentes qualitativamente; mas algumas questões referentes aos modelos físico e numérico escolhidos ainda limitam a precisão dos resultados e restringem sua adoção em atividades de engenharia. Entretanto, diversas características observadas no escoamento contribuem para aumentar o conhecimento de alguns fenômenos envolvidos no problema. / This work is about the hull and propeller interaction in joint functioning, and its simulation by computational tools. The text concentrates in describing the main effects of such interaction, the main difficulties in the estimation of these effects, the methods traditionally adopted, and how computational tools can be applied in advantageous way. A critical analysis of the most common methods and results, based on paperworks of several different authors worldwide, can also be found. The Finite Volumes method, used in this research, is presented - its main issues, advantages and disadvantages, and the simulations outcomes, compared to the experimental values and explained by the knowledge of the Finite Volumes method limitations. The comparison is made by means of both integral values, such as the hull\'s resistance or the propeller thrust; as well as the characteristics of the flow, like the wake velocity profile, presence of vortex, and other typical structures. The results shows the same error band than the ones which has been obtained by other researchers, worldwide, and most of the typical characteristics of the flow were observed. But some issues concerned to the chosen physical and numerical models still limit the precision of the outcomes, and restrict the application of such models at engineering activities. But several insights about the flow, obtained at this study, can be useful to the understanding of some phenomena involved in the propeller operation.

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2014-11-21T13:26:38Z No. of bitstreams: 2 Dissertação - Kariton Pereira Lula - 2013.pdf: 688910 bytes, checksum: ee9fb2513092c9a3acc4ff5dcbf906a2 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2014-11-24T10:05:51Z (GMT) No. of bitstreams: 2 Dissertação - Kariton Pereira Lula - 2013.pdf: 688910 bytes, checksum: ee9fb2513092c9a3acc4ff5dcbf906a2 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2014-11-24T10:05:51Z (GMT). No. of bitstreams: 2 Dissertação - Kariton Pereira Lula - 2013.pdf: 688910 bytes, checksum: ee9fb2513092c9a3acc4ff5dcbf906a2 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2013-02-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / In elementary mathematics teaching, it often occurs that some subjects are presented without proper justi cation or without a coherent logical construction that makes sense of those subjects and ideas in a wider context. The calculation of areas and volumes is an example of a subject in which these shortcomings are usually present. In this work, we present a model for the gradual development of the ideas involved in the calculation of volumes, in a way that is, at once, well justi ed and approachable by the average student at this stage. In order to achieve that, we make extensive use of the Cavalieri Principle, which allows not only an adequate justi cation of the expressions for the volume of cylinders, cones or spheres, but also the calculation of volumes of other shapes, such as parts of the sphere, ellipsoids and paraboloids. We conclude with an interesting application of the Cavalieri Principle to calculate the area of a parabolic segment and then give a demonstration of Archimedes' theorem. / Frequentemente, no ensino básico, conteúdos de matemática são apresentados sem justi cativas satisfatórias, as vezes até sem justi cativas e sem um desenvolvimento lógico que faça sentido desses conteúdos e ideias num contexto mais amplo. O cálculo de áreas e volumes é um exemplo de conteúdo em que estas de ciências normalmente ocorrem. Neste trabalho, apresentamos um modelo de desenvolvimento progressivo dos conceitos envolvidos no cálculo de volumes, com uma fundamentação que seja, ao mesmo tempo, satisfatória e acessível ao nível de desenvolvimento do estudante. Para isso, fazemos extensivo uso do Princípio de Cavalieri, que permite não só justi car adequadamente o cálculo do volume de cilindros, cones ou esferas, mas também fazer sentido o cálculo de volume de outros tipos de regiões, como partes da esfera, elipsóides e parabolóides. Concluímos com uma interessante aplicação do Princípio de Cavalieri ao cálculo da área delimitada por um segmento de parábola e a consequente demonstração do Teorema de Arquimedes a esse respeito.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-05-12T12:03:39Z No. of bitstreams: 1 marcioeduardoprimo.pdf: 7986149 bytes, checksum: 314d24f9529761ede11a698feb79db7e (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-06-27T19:31:40Z (GMT) No. of bitstreams: 1 marcioeduardoprimo.pdf: 7986149 bytes, checksum: 314d24f9529761ede11a698feb79db7e (MD5) / Made available in DSpace on 2016-06-27T19:31:40Z (GMT). No. of bitstreams: 1 marcioeduardoprimo.pdf: 7986149 bytes, checksum: 314d24f9529761ede11a698feb79db7e (MD5) Previous issue date: 2013-03-25 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Neste trabalho apresentamos uma sequência de atividades utilizando o Princípio de Cavalieri no cálculo de volumes de sólidos geométricos. Essas atividades são destinadas a alunos do Ensino Médio, partindo do pressuposto que já é do conhecimento desses alunos, o cálculo do volume de um bloco retangular. A partir dessa condição, apresentamos o Princípio de Cavalieri como axioma em atividades que despertam a intuição dos estudantes, para que compreendam e aceitem esse Princípio. Os alunos são levados a participar de forma ativa na dedução das fórmulas para o cálculo do volume dos sólidos tradicionais como: pirâmides, cones, cilindros e esferas. Com o auxílio do software de Geometria Dinâmica GeoGebra 5.0 JOGL1 Beta 3D, criamos figuras e animações que facilitam a visualização dos sólidos geométricos, bem como a criação de conjecturas que auxiliam os alunos na dedução das fórmulas. Além desses sólidos que chamamos de tradicionais, apresentamos outros exemplos de aplicação do Princípio de Cavalieri que não são comumente encontrados em livros destinados a esse nível de ensino: o toro, uma esfera com furo cilíndrico. Como última atividade, consideramos o sólido formado na interseção entre dois cilindros de mesmo raio com seus eixos perpendiculares, sendo a altura desses cilindros maior que o diâmetro da base. Esse cálculo de volume é comumente apresentado em livros de Ensino Superior com a utilização do Cálculo Integral mas, nesse trabalho, levamos os alunos a deduzir a fórmula para o cálculo desse volume utilizando o Princípio de Cavalieri. / In this work we present a sequence of activities using the Cavalieri’s Principle in calculating volumes of geometric solids. These activities are aimed at high school students who know how to calculate the volume of a rectangular block. From this condition, we introduce Cavalieri’s Principle as an axiom in activities that awaken students’ intuition so that they understand and accept this principle. Students are led to participate actively in the derivation of formulas for calculating the volume of solids as traditional pyramids, cones, cylinders and spheres. With the help of Dynamic Geometry software GeoGebra 5.0 Beta JOGL1 3D, we create pictures and animations that will facilitate the visualization of geometric solids as well as the creation of conjectures as assist students in understanding formulas. Besides these solids which will we call traditional, other examples will be presented in order to apply the Cavalieri’s Principle which are not commonly found in books aimed at this level of education: the torus, a sphere with a cylindrical bore. As a final activity, we consider the solid formed by the intersection by two cylinders of the same radius with their perpendicular axes, their heights are greater than the cylinder diameter of the base. This volume calculation is commonly presented in College textbooks using the Integral Calculus, but in this work we take students to understand the formula by calculating the volume using the Cavalieri’s Principle.

Les ombres sont un élément fondamental pour garantir le réalisme des images de synthèses. Elles donnent des informations nécessaires pour discerner correctement le positionnement relatif des objets. Le calcul d'ombre dures exactes en temps-réel reste toutefois un problème difficile en Informatique Graphique. Les Shadow Maps sont privilégiées pour leurs excellentes performances, mais elles ne peuvent garantir un résultat exact par pixel. Les volumes d'ombre sont plus lents que les Shadow Maps mais produisent des ombres exactes en toute circonstances. Bien qu'ils aient récemment atteint un haut niveau de performances, ils restent sensibles à la complexité géométrique et sont limités à des scènes de taille modeste. Dans cette thèse, nous proposons un nouvel algorithme de rendu d'ombres dures en temps réel basé sur les volumes d'ombre qui reste rapide sur des scènes de très grande tailles. De plus, nous introduisons une nouvelle stratégie de partitionnement jusque-là inexplorée en Informatique Graphique : les arbres métriques. / Shadows are a fundamental visual effect for computer generated images. They provide essential spatial hints allowing us to correctly perceive objects positions in the scene. Despite its importance, computing pixel accurate shadows in real-time is a challenging problem in Computer Graphics. Shadow Maps are still the favored solution due to their high efficiency, but they can't always provide pixel accurate results. Shadow Volumes are slower than Shadow Maps but always garantee pixel accurate shadows. While recent works significantly improved their performance, they remain sensitive to scalability, which limits their application scope. In this thesis, we propose a new algorithm based on Shadow Volumes that remains fast even on very large scenes. Furthermore, we introduce a new partitioning strategy that is yet unexplored in Computer Graphics : the metric tree.

Retracer l’histoire d’un bassin est un préalable essentiel à toute recherche d’hydrocarbures. Pour cela, on a recours à un modèle stratigraphique, qui simule l'évolution des bassins sédimentaires sur de grandes échelles de temps (millions d'années) et d'espace (centaines de kilomètres). Le logiciel Dionisos, développé à IFPEN depuis 1992 et très apprécié par les compagnies pétrolières, permet d’effectuer ce type de calculs en prenant en compte deux grands processus physiques : (1) le transport gravitaire des sédiments dû à l’inclinaison du sol ; (2) l’écoulement de l’eau provenant des fleuves et des précipitations. Le transport gravitaire est décrit par une équation de diffusion dans laquelle le flux de sédiments dépend de la pente du sol. Initialement, cette dépendance est linéaire. Pour mieux s’approcher des observations réelles, on souhaite la rendre non-linéaire par l’intermédiaire d’un p-Laplacien. Ce changement nécessite la conception d’une nouvelle méthode de résolution numérique, qui doit offrir non seulement une grande rapidité d’exécution, mais aussi des garanties de robustesse et de précision des résultats. De plus, elle doit être compatible avec une contrainte sur le taux d’érosion présente dans le modèle. L’ajout de l’écoulement de l’eau est aussi une sophistication récente du modèle physique de Dionisos. Il se traduit par l’introduction d’une nouvelle équation aux dérivées partielles, couplée à celle du transport. Là encore, il est important d’élaborer une stratégie de résolution numérique innovante, en ce sens qu’elle doit être à la fois performante et bien adaptée au fort couplage de ces deux phénomènes. L'objectif de cette thèse est de moderniser le cœur numérique de Dionisos afin de traiter plus adéquatement les processus physiques ci-dessus. On cherche notamment à élaborer un schéma implicite par rapport à toutes les inconnues qui étend et améliore le schéma actuel. Les méthodologies retenues serviront de base à la prochaine génération du calculateur. / An essential prerequisite to finding hydrocarbons is to trace back the history of a basin. To this end, geologists resort to a stratigraphic model, which simulates the evolution of sedimentary basins over large time scales (million years) and space (hundreds of kilometers). The Dionisos software, developed by IFPEN since 1992 and highly praised by oil companies, makes this type of calculation possible by accounting for two main physical processes: (1) the sediment transport due to gravity; (2) the flow of water from rivers and rains. The gravity transport is described by a diffusion equation in which the sediment flow depends on the slope of the ground. Initially, this dependence is linear. To better match experimental observations, we wish to make it nonlinear by means of a p-Laplacian. This upgrade requires to design a dedicated numerical method which should not only run fast but also provide guarantees of robustness and accuracy. In addition, it must be compatible with a constraint on the erosion rate in the present model. The water flow due to rivers and rains is also a recent enhancement brought to the physical model of Dionisos. This is achieved by introducing a new partial differential equation, coupled with that of sediment transport. Again, it is capital to work out an innovative numerical strategy, in the sense that it must be both efficient and well suited to the strong coupling of these two phenomena. The objective of this thesis is to rejuvenate the numerical schemes that lie at the heart of Dionisos in order to deal more adequately with the physical processes above. In particular, we look for an implicit scheme with respect to all the unknowns that extends and improves the current scheme. The methodologies investigated in this work will serve as a basis for the next generation of stratigraphic modelling softwares.

“I want my street to be like an extension to my driveway, where the kids can play safely and where the traffic does not bother us,” said one resident. Another said that she “likes traffic... We live in a city.” This gives an idea of the broad range of opinions and views that exist on traffic. Traffic in local streets in a concern for residential amenity. There is always conflict between the residential amenity and traffic access functions of local streets. There is much debate on what a true local road is. The concept of environmental capacity was developed to identify a suitable maximum traffic volume on local streets, without overly adversely affecting residents. It was first introduced by Buchanan and Appleyard in separate research in the 1960s. Both men settled on thresholds of 2,000-3,000 vehicles per day. Chesterman, in 2009, carried out a study in Christchurch, surveying residents on four local streets with varying traffic volumes. He found residents living on busier streets felt that their streets were busier, noisier and less safe. There was also an increasing trend for these residents to have their houses turned away from the street and they tended to have less personal involvement with their neighbours. He found that perhaps a more suitable environmental capacity estimate was between 1,500 and 2,000 vehicles per day. This study looked at further Christchurch streets, this time with street treatments, such as street calming and tree plantings, aiming to find an environmental capacity for these streets as well as seeing whether the street treatments affected the perceived environmental capacity. As well as reinforcing most of the conclusions found by Chesterman, a higher environmental capacity of around 2,000 vehicles per day was found for the surveyed streets. This suggests that indeed, street treatments such as those used in the surveyed streets can increase the environmental capacity, which has implications for local councils who want to maintain road traffic carrying capabilities without having unsatisfied residents.