Les propriétés de symétrie d'un objet représenté sous la forme d'un modèle B-Rep CAO sont analysées localement et globalement à travers une approche de type diviser pour conquérir. La surface frontière de l'objet est décrite à partir de surfaces canoniques fréquemment utilisées dans les formes de composants mécaniques. La première phase de l'analyse consiste en la génération de faces et d'arêtes maximales indépendantes du processus de modélisation de l'objet mais préservant ses propriétés de symétrie. Ces faces et arêtes constituent des ensembles infinis de points traités globalement. La seconde phase est l'étape de division consistant en la création de plan et axes de symétrie de candidats pour les faces et arêtes maximales générées précédemment. Enfin, suit l'étape de propagation de ces plans et axes de symétrie représentant la phase de conquête et déterminant les propriétés de symétrie locales et globales de l'objet et caractérisant ses zones non-symétriques. / Symmetry properties of objects described as B-Rep CAD models are analyzed locally as well as globally through an approach of type divide-and-conquer. The boundary of the object is defined using canonical surfaces frequently used when shaping mechanical components. Then, the first phase consists in generating maximal faces and edges that are independent from the object modelling process but that preserve its symmetry properties. These faces and edges form infinite sets of points that are processed globally. The second phase is the division one that creates candidate symmetry planes and axes attached to the previous maximal edges and faces. Finally, comes the propagation step of these candidate symmetry planes and axes forming the conquer phase that determines the local as well as the global symmetries of the object while characterizing its asymmetric areas.

Os objetivos gerais deste trabalho foram estudar o comportamento de densificação e as propriedades mecânicas do nitreto de alumínio (AlN) com aditivo de sinterização. Os objetivos específicos foram estudar: 1) o efeito do teor de Y2O3 na densificação do AlN; 2) o efeito da adição de carbono na densificação do AlN com CaO; 3) o efeito da adição simultânea de Y2O3 e CaO na densificação do AlN; 4) o efeito da porosidade nas propriedades elásticas do AlN com Y2O3 ou CaO; e 5) o efeito do teor de Y2O3 ou CaO nas propriedades mecânicas do AlN. As amostras foram sinterizadas sob atmosfera inerte em várias temperaturas (1100-2000ºC) e analisadas por determinação de densidade, difração de raios X e microscopia eletrônica de varredura. As propriedades determinadas à temperatura ambiente foram: constantes elásticas pelo método de pulso-eco ultra-sônico, resistência à flexão biaxial, dureza Vickers e tenacidade à fratura pelos métodos Indentation Fracture (KIc-IF) e Indentation Strength (KIc-IS). O AlN com Y2O3 apresentou significativa densificação por sinterização no estado sólido, mas completa densificação ocorreu somente por sinterização via fase líquida. A densificação do AlN não foi influenciada pelo aumento de 0,5% a 4% de Y2O3, pois a temperatura de formação da fase líquida (~ 1725ºC) não variou nesta faixa de teor de aditivo. Porém, a adição de carbono levou à formação de segundas-fases refratárias no AlN com 4% de Y2O3, o que atrasou sua densificação devido ao aumento da temperatura de formação da fase líquida. A adição de carbono não mudou a temperatura de formação da fase líquida do AlN com 4% de CaO sinterizado acima de 1650ºC, mas sua densificação também atrasou devido à diminuição da fração de fase líquida e ao aprisionamento de gás nos poros fechados. A adição simultânea de CaO e Y2O3 diminuiu significativamente a temperatura de sinterização do AlN em relação às adições individuais destes aditivos. O AlN com mistura de CaO e Y2O3 atingiu quase completa densificação a partir de 1650ºC devido à formação de fase líquida com composição próxima da fase CaYAl3O7, que apresentou boas características de molhamento e espalhamento nesta temperatura de sinterização. A adição de carbono mudou a composição das segundas-fases de CaYAl3O7 para CaYAlO4 e, então, para YAM (2Y2O3.Al2O3) no AlN com mistura de CaO e Y2O3, o que atrasou sua densificação em baixas temperaturas de sinterização (< 1700ºC) devido à alta viscosidade e/ou baixa molhabilidade da fase CaYAlO4 e à alta refratariedade da fase YAM. As propriedades elásticas, bem como a dureza Vickers do AlN foram influenciadas pela porosidade, mas não foram influenciadas pelo tipo (CaO e Y2O3) e teor (0,5% a 8% em massa) de aditivo de sinterização. A resistência 7 à flexão foi influenciada pelo tipo e teor de aditivo de sinterização, sendo observado um teor crítico de aditivo, acima do qual esta propriedade diminuiu significativamente e, então, tendeu a permanecer constante em função do teor de aditivo. Não se observou correlação entre tenacidade à fratura e resistência à flexão. Os valores de KIc-IS, que não variaram com o tipo e teor de aditivo de sinterização, foram considerados mais consistentes do que os valores de KIc-IF. / The general objectives of this work were to study the densification behavior and the mechanical properties of aluminum nitride (AlN) with sintering aid. The specific objectives studied were: 1) the effect of Y2O3 content on the densification of AlN, 2) the effect of carbon addition on the densification of AlN with CaO, 3) the effect of simultaneous addition of Y2O3 and CaO on the densification of AlN; 4) the effect of porosity on elastic properties of AlN with CaO or Y2O3, and 5) the effect of Y2O3 or CaO content on the mechanical properties of AlN. The samples were sintered under inert atmosphere at various temperatures (1100ºC-2000ºC) and analyzed by density measurement, X-ray diffraction and scanning electron microscopy. The properties measured at room temperature were: elastic constants by the ultrasound pulse-echo method, biaxial flexural strength, Vickers hardness and fracture toughness by the Indentation Fracture (IF) and Indentation Strength (IS) methods. AlN with Y2O3 presented significant densification by solid-state sintering, but full densification occurred only by liquid-phase sintering. The densification of AlN was not influenced by the increase of 0.5% to 4% Y2O3, since the liquid-phase formation temperature (~ 1725ºC) did not change in this range of additive content. However, the addition of carbon to AlN with 4% Y2O3 led to formation of refractory second-phases, which delayed the densification due to an increase of the liquid-phase formation temperature. The addition of carbon did not change the liquid-phase formation temperature of AlN with 4% CaO sintered above 1650ºC, but its densification delayed significantly due to the diminution of liquid-phase fraction and trapped gas in closed pores. The simultaneous addition of CaO and Y2O3 significantly diminished the sintering temperature of AlN in relation to the individual additions of these additives. AlN with simultaneous addition of CaO and Y2O3 achieved almost full densification at 1650ºC due to formation of liquid-phase with composition close to CaYAl3O7 phase, which had good wetting and spreading characteristics at this temperature. The addition of carbon changed the composition of second-phases from CaYAl3O7 to CaYAlO4 and then to YAM (2Y2O3.Al2O3) in AlN with simultaneous addition of CaO and Y2O3, delaying its densification at low sintering temperatures (< 1700ºC) due to the high viscosity and/or low wettability of CaYAlO4 phase and high refractoriness of YAM phase. The elastic properties, as well as Vickers hardness were influenced by the increase of porosity, but were not influenced by type (CaO and Y2O3) and content (0.5% to 8% in mass) of sintering aid. Flexure strength was influenced by the type and content of sintering aid. It was observed a critical additive content, 9 above which the strength decreased significantly and then tended to remain almost constant as a function of additive content. No relationship was observed between fracture toughness and flexure strength. The KIc-IS values, which did not vary with type and content of sintering aid, were found to be more consistent than the KIc-IF values.

Les méthodes actuelles d’optimisation de formes permettent des gains importants vis-à-vis des fonctions à optimiser. Elles sont largement utilisées par les industriels, notamment dans l’automobile comme chez Renault. Parmi ces approches, l’optimisation de formes paramétriques permet d’obtenir rapidement une géométrie optimale sous réserve que l’espace de conception soit assez restreint pour pouvoir être parcouru en un temps de simulation raisonnable. Ce manuscrit présente deux méthodes d’optimisation de formes paramétriques en grande dimension pour des applications nécessitant des coûts de calculs importants, par exemple en mécanique des fluides. Une manière originale de reconstruire un modèle CAO paramétré à partir d’une surface morte est présentée au préalable. Nous proposons une approche pour identifier les zones interdites de l’espace de conception ainsi que leurs gestions dans une boucle d’optimisation par plans d’expériences. La première méthode s’appuie sur des techniques statistiques pour lever le verrou du nombre de degrés de liberté et utilise une optimisation à deux niveaux de fidélité pour minimiser les temps de calcul. Cette méthode en rupture avec le processus industriel habituel a été appliquée pour optimiser le coefficient de trainée aérodynamique d’un véhicule. La seconde méthode se base sur l’exploitation des gradients fournis par les solveurs adjoints, c’est-à-dire sur les sensibilités du critère (comme l’uniformité d’un écoulement par exemple) par rapport aux degrés de liberté de l’optimisation. Cette méthode innovante et en rupture avec les approches classiques permet de lever très naturellement le verrou du nombre de paramètres. Cependant, les gradients fournis par les logiciels ne sont pas donnés par rapport aux paramètres CAO mais par rapport aux nœuds du maillage. Nous proposons donc une façon d’étendre ces gradients jusqu’aux paramètres CAO. Des exemples académiques ont permis de montrer la pertinence et la validité de notre approche. / Current design loops for shape optimizations allow significant improvements in relation to the functions that need to be optimized. They are widely used in industry, particularly in the car industry like Renault. Among these approaches, parametric shape optimization allows rapid enhancement of the shape, on the condition that the design space is confined enough in order to be explored within a reasonable computational time. This Thesis introduces two CAD-based large-scale shape optimization methods for products requiring significant computational cost, for example in fluid mechanics. An original way to create a parameterized CAD model developed from a dead geometry is presented first. We propose an approach to identify the restricted areas of the design space and their managements in an optimization loop that uses a design of experiments. The first method is based on statistical techniques to circumvent the difficulties of large-scale optimizations and uses a two-level multi-fidelity modelling approach to minimize the computational time. This method, breaking away from the usual industrial process, was applied to optimize the aerodynamic drag coefficient of a car body. The second method is based on the gradients provided by adjoint solvers, that is to say on the sensitivity of the cost function (such as the uniformity deviation for example) with respect to the design points or displacement boundaries. This innovative method breaking away from classical approaches naturally gets over the number of degrees of freedom. However, the sensitivities provided by softwares are not computed with respect to CAD parameters but with respect to the coordinates of the vertices of the surface mesh. Thus, we propose a way to extend these gradients to CAD parameters. Academic test cases have proved the efficiency and accuracy of our method.

Orientador: Fernão Vitor Pessoa de Almeida Ramos / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Artes / Made available in DSpace on 2018-08-26T08:56:07Z (GMT). No. of bitstreams: 1 Hosni_CassiaTakahashi_M.pdf: 6735968 bytes, checksum: 0cf70d146a084d5f759ce85ce7eff2cf (MD5) Previous issue date: 2014 / Resumo: O presente trabalho aborda o conjunto de obras do artista visual e cineasta Cao Guimarães, percorrendo panoramicamente sua trajetória de 1986 a 2013. A pesquisa se propõe a entender quais são as linhas de pensamento do artista e de que modo elas influenciam seus métodos e processos autorais. Para isso, seus longas e curtas- metragens, séries fotográficas, instalações e produções textuais foram elencados como num inventário cronológico. A descrição analítica desse inventário pretende descobrir elementos poéticos constantes no interior da pluralidade de linguagens que permeiam a produção do artista / Abstract: This research discusses the collection of works of the visual artist and filmmaker Cao Guimarães, panoramically going over its trajectory from 1986 to 2013. The research aims at understanding which are the lines of thought of the artist and how they influence the author's methods and creative process. For this purpose, his feature and short films, photographic series, art installations and textual production have been listed in a chronological inventory. The analytical description of this inventory intends to unveil the poetic elements contained within the plurality of languages that permeate the artist's production / Mestrado / Multimeios / Mestra em Multimeios

Dans ce manuscrit, nous présentons une méthode d’optimisation de forme qui se base sur des paramètres géométriques comme des longueurs, des angles, etc. Nous nous appuyons sur des techniques d’optimisation basées sur un gradient. La sensibilité de la fonction objectif par rapport à la position des noeuds du maillage nous est fournie par un solveur adjoint que l’on considère comme une boîte noire. Afin d’optimiser par rapport aux paramètres CAO, nous nous concentrons sur l’évaluation de la sensibilité de la position des noeuds par rapport à ces paramètres. Ainsi, nous proposons deux approches par différences finies. La première méthode s’appuie sur une projection harmonique afin de comparer dans un même espace le maillage initial et celui obtenu suite à la variation d’un paramètre CAO. Les développements présentés dans ce manuscrit permettent d’étendre l’application aux formes ayant plusieurs frontières comme les collecteurs d’échappement. Nous avons développé une méthode d’interpolation adaptée à cette comparaison. L’ensemble du processus a été automatisé et nous en montrons l’entière efficacité sur des applications industrielles en aérodynamique interne. La deuxième méthode se base directement sur les géométries CAO pour évaluer cette sensibilité. Nous utilisons la définition intrinsèque des patches dans l’espace paramétrique (u;v) pour effectuer cette comparaison. Grâce à l’utilisation des coordonnées exactes en tout point de la surface fournies par la CAO, nous évitons d’avoir recours à une interpolation afin d’avoir la meilleure précision de calcul possible. Cependant, contrairement à la première méthode, elle requiert d’identifier les correspondances entre les patches d’une forme à l’autre. Une application sur un cas académique a été faite en aérodynamique externe. La pertinence de la première méthode a été démontrée sur des cas représentatifs et multiobjectifs, ce qui permettrait de faciliter son déploiement et son utilisation dans un cadre industriel. Quant à la deuxième méthode, nous avons montré son fort potentiel. Cependant, des développements supplémentaires seraient nécessaires pour une application plus poussée. Du fait qu’elles sont indépendantes des solveurs mécaniques et du nombre de paramètres, ces méthodes réduisent considérablement les temps de développement des produits, notamment en permettant l’optimisation multiphysique en grande dimension. / In this manuscript, we present a shape optimization method based on CAD parameters such as lengths, angles, etc. We rely on gradient-based optimization techniques. The sensitivity of the objective function, with respect to the mesh nodes position, is provided by an adjoint solver considered here as a black box. To optimize with respect to CAD parameters, we focus on computing the sensitivity of the nodes positions with respect to these parameters. Thus, we propose two approaches based on finite differences. The first method uses a harmonic projection to compare in the same space the initial mesh and the one obtained after a change of the set of CAD parameters. The developments presented in this manuscript open up new doors like the application to shapes with multiple borders such as exhaust manifolds. We also developed an interpolation method suitable for this comparison. The entire process is automated, and we demonstrate the entire effectiveness on internal aerodynamics industrial applications. The second method is directly based on the CAD geometries to assess this sensitivity. To perform this comparison, we use the intrinsic definition of the patches in the parametric space (u;v). Through the use of the exact coordinates at any point on the surface provided by the CAD, we avoid using an interpolation to get the best calculation accuracy possible. However, unlike the first method, it requires to identify the correspondence between patches from one shape to another. An application on an external aerodynamics academic case was made. The relevance of the first method is demonstrated on a representative multi-objective case, which facilitate its deployment use in an industrial environment. Regarding the second method, we showed its great potential. However, further developments are needed to handle more advanced cases. Because they are independent of the mechanical solver and the number of parameters, these methods significantly reduce product development time, particularly by allowing large and multiphysics optimization.

Expone los resultados de la investigación etnográfica realizada en el distrito de Magdalena de Cao, ubicado en el departamento de la Libertad. La investigación pretende aportar a la comprensión de los cambios que se han generado en la producción, tradición, e identidad de los productores de chicha de año. Esta es una bebida alcohólica tradicional que junto al descubrimiento arqueológico de la “Señora de Cao”, constituye uno de los elementos emblemáticos del distrito. A partir de la llegada de instituciones vinculadas a proyectos de desarrollo y puesta en valor, los cambios en la tradicional producción de chicha de año se han vuelto más dinámicos. En este proceso se han identificado un grupo de chicheros con disposición a los cambios en el discurso y en las técnicas de producción, y un grupo de chicheros renuentes. Se analizaran los factores sociales y económicos que influyen en este proceso. / Tesis

Bionischer Leichtbau realisiert mit Applikationen an gängige FEM-Programme nach dem Vorbild der Natur

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The effect of individual additions of calcium oxide (CaO), Gd, Nd and Y was investigated on the microstructure, mechanical properties and corrosion resistance of the as-cast ZK40 alloy. The microstructural features were analised using optical, scanning and transmission electron microscopy, X-ray diffraction and Scanning Kelvin Atomic Probe Force Microscopy. The compressive and tensile behaviours of the as-cast alloys at room temperature were investigated. Electrochemical Impedance Spectroscopy, hydrogen evolution and weight loss under immersion in 0.5 wt.% NaCl solution were used to evaluate the corrosion behaviour. The results of the mechanical and corrosion tests were correlated with the microstructures. The 2 wt.% Gd addition enhanced the ductility, while the Nd addition resulted in deterioration in mechanical properties. The addition of 2 wt.% Gd and 1 wt.% Y resulted in the improvement of the ductility. The addition of CaO did not affect the mechanical properties while the 2 wt.% Nd deteriorate it. The 1 wt.% Y addition enhanced the ductility. The CaO addition did not caused enhancement in mechanical properties. The corrosion behaviour was enhanced with the addition of CaO and Gd. The modification of ZK40 with Gd opens up new perspectives in the development of Mg-Zn based alloys. / O efeito da adição individual de óxido de cálcio (CaO), Gd, Nd e Y foi investigado na microestrutura, propriedades mecânicas e resistência à corrosão de ligas ZK40 fundidas. As características microestruturais foram analisadas via microscopia óptica, microscopia eletrônica de varredura, microscopia eletrônica de transmissão, difração de Raios-X e \"Scanning Kelvin Atomic Probe Force Microscopy\". O comportamento à compressão e à tração das ligas à temperatura ambiente foi investigado. Espectroscopia eletroquímica de impedância, evolução de hidrogênio e ensaios de imersão em solução de 0.5% em peso de NaCl foram utilizados para avaliar a resistência à corrosão. Os resultados dos ensaios mecânicos e corrosão foram relacionados com a microestrutura. A adição de 2% em peso de Gd melhorou a ductilidade, ao passo que a adição de Nd resultou na piora das propriedades mecânicas. A adição de 2% em peso de Gd e 1% em peso de Y resultou na melhora da ductilidade. A adição de 1% em peso de Y causou uma melhora na ductilidade e a adição de CaO não teve impacto benéfico nas propriedades mecânicas. A resistência à corrosão foi melhorada com a adição de CaO e Gd. A modificação da liga ZK40 com a adição de Gd abre novas perspectivas no desenvolvimento de ligas Mg-Zn.

The effect of individual additions of calcium oxide (CaO), Gd, Nd and Y was investigated on the microstructure, mechanical properties and corrosion resistance of the as-cast ZK40 alloy. The microstructural features were analised using optical, scanning and transmission electron microscopy, X-ray diffraction and Scanning Kelvin Atomic Probe Force Microscopy. The compressive and tensile behaviours of the as-cast alloys at room temperature were investigated. Electrochemical Impedance Spectroscopy, hydrogen evolution and weight loss under immersion in 0.5 wt.% NaCl solution were used to evaluate the corrosion behaviour. The results of the mechanical and corrosion tests were correlated with the microstructures. The 2 wt.% Gd addition enhanced the ductility, while the Nd addition resulted in deterioration in mechanical properties. The addition of 2 wt.% Gd and 1 wt.% Y resulted in the improvement of the ductility. The addition of CaO did not affect the mechanical properties while the 2 wt.% Nd deteriorate it. The 1 wt.% Y addition enhanced the ductility. The CaO addition did not caused enhancement in mechanical properties. The corrosion behaviour was enhanced with the addition of CaO and Gd. The modification of ZK40 with Gd opens up new perspectives in the development of Mg-Zn based alloys. / O efeito da adição individual de óxido de cálcio (CaO), Gd, Nd e Y foi investigado na microestrutura, propriedades mecânicas e resistência à corrosão de ligas ZK40 fundidas. As características microestruturais foram analisadas via microscopia óptica, microscopia eletrônica de varredura, microscopia eletrônica de transmissão, difração de Raios-X e \"Scanning Kelvin Atomic Probe Force Microscopy\". O comportamento à compressão e à tração das ligas à temperatura ambiente foi investigado. Espectroscopia eletroquímica de impedância, evolução de hidrogênio e ensaios de imersão em solução de 0.5% em peso de NaCl foram utilizados para avaliar a resistência à corrosão. Os resultados dos ensaios mecânicos e corrosão foram relacionados com a microestrutura. A adição de 2% em peso de Gd melhorou a ductilidade, ao passo que a adição de Nd resultou na piora das propriedades mecânicas. A adição de 2% em peso de Gd e 1% em peso de Y resultou na melhora da ductilidade. A adição de 1% em peso de Y causou uma melhora na ductilidade e a adição de CaO não teve impacto benéfico nas propriedades mecânicas. A resistência à corrosão foi melhorada com a adição de CaO e Gd. A modificação da liga ZK40 com a adição de Gd abre novas perspectivas no desenvolvimento de ligas Mg-Zn.