Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / A utilizaÃÃo de vigas laminadas de parede fina nas Engenharias AeronÃutica, Civil, MecÃnica e Naval tem crescido bastante nos Ãltimos anos, devido a suas elevadas relaÃÃes rigidez/peso e resistÃncia/peso. Esses elementos estruturais normalmente apresentam paredes finas devido à alta resistÃncia dos materiais compÃsitos. Outra caracterÃstica importante à que, mesmo sem apresentar grandes deformaÃÃes e sem que o limite elÃstico do material seja ultrapassado, estas vigas apresentam comportamento nÃo linear geomÃtrico devido à sua elevada esbeltez, acarretando em grandes deslocamentos e rotaÃÃes. Dependendo da laminaÃÃo utilizada, as vigas de materiais compÃsitos podem apresentar diversos acoplamentos entre esforÃos e deformaÃÃes, tornando a sua anÃlise bem mais complexa do que a anÃlise de vigas de material isotrÃpico. Neste trabalho, foram desenvolvidos dois elementos finitos de pÃrtico espacial para anÃlise nÃo linear geomÃtrica de vigas laminadas de parede fina. As propriedades seccionais da viga sÃo avaliadas atravÃs de teorias de vigas laminadas de parede fina apropriadas, em que desprezam-se os efeitos do empenamento e do cisalhamento transversal. Tais teorias de vigas laminadas conduzem a uma matriz constitutiva 4x4, onde diferentes nÃveis de acoplamento entre esforÃos e deformaÃÃes de viga sÃo considerados, por exemplo, pode-se obter uma matriz constitutiva diagonal ou cheia. A abordagem corrotacional independente do elemento à utilizada para o tratamento de grandes deslocamentos e rotaÃÃes de corpo rÃgido no espaÃo. No Ãmbito local, sÃo utilizados dois elementos, um baseado na teoria linear e outro na descriÃÃo Lagrangeana Total. O tratamento matemÃtico das grandes rotaÃÃes no espaÃo à realizado por meio do tensor das rotaÃÃes (fÃrmula de Rodrigues), juntamente com o conceito do pseudovetor. As implementaÃÃes dos elementos finitos propostos neste trabalho sÃo realizadas no software de cÃdigo aberto FAST. A metodologia de trabalho segue o roteiro clÃssico de mÃtodos computacionais, incluindo formulaÃÃo, implementaÃÃo, verificaÃÃo e validaÃÃo dos resultados. A verificaÃÃo à realizada atravÃs dos modelos tridimensionais de elementos finitos de casca e sÃlido desenvolvidos no software comercial ABAQUS. A validaÃÃo à realizada por meio da comparaÃÃo com resultados de ensaios experimentais encontrados na literatura. No que diz respeito à avaliaÃÃo das propriedades seccionais, pode-se verificar uma Ãtima concordÃncia entre as teorias de vigas laminadas adotadas neste trabalho e os resultados numÃricos e de ensaios experimentais, para todas as laminaÃÃes e carregamentos considerados. No caso dos elementos de pÃrtico espacial, verificou-se uma Ãtima concordÃncia entre os resultados dos elementos finitos propostos neste trabalho e os resultados analÃticos e computacionais disponÃveis na literatura. Observa-se tambÃm que o elemento baseado na descriÃÃo Lagrangeana à mais eficiente do que o elemento baseado na teoria linear no que tange à capacidade de apresentar uma resposta satisfatÃria com uma malha menos refinada. / The use of thin walled laminate beams in Aeronautical, Civil, Mechanical and Naval Enginee- ring is increasing in the last years. This is due to their high stiffness/weight and strength/weight ratios. Composite beams and other structural elements tend to have thin walls due to the elevated strength of the material. Other important aspect is that, even without reaching large strains and without overcoming the elastic limit of the material, such beams present geometric nonlinear behavior due to high their slenderness, leading to large displacements and rotations. Depen- ding on the composite layup, the beams of composite materials can present several couplings between generalized stresses and strains, requiring a more complex analysis procedure when compared to isotropic beams. In this work, two three-dimensional space frame finite elements that can be used to analyze composite thin-walled beams subjected to geometric non-linearity were developed. The cross-section properties of the beams are evaluated through suitable thin walled beam theories, where the effects of the warping and transverse shear are neglected. Such theories yield a 4x4 constitutive matrix for the laminate and different levels of coupling between generalized stresses and strains can be considered. Depending of such couplings, the constitu- tive matrix can either be full or diagonal. The element independent corotational approach was used in order to consider large displacaments and rigid body rotations in space. In the local coordinate system, two elements are used, one based on the linear strain theory and the other on the Total Lagrangian formulation. The mathematical treatment of the large rotations in the space is performed by means of the rotation tensor (Rodriguesâs formula) in conjunction with the concept of the pseudovector. The computational implementations of the two finite elements proposed in this work were done in the open source software FAST ( Finite Element Analysis Tool ). The methodology used follows the classical steps used in computational methods, in- cluding formulation, implementation, verification and validation of results. Such verification is accomplished through shell and solid three-dimensional finite element models developed in the ABAQUS commercial software. The validation is performed by means of comparison with the experimental results found in literature. Regarding the evaluation of cross-sectional properties, one can observe a good agreement between the laminated beam theories adopted in this work and numerical and experimental results for all composite layups and load conditions conside- red. In the case of space frame elements, a good agreement is obtained between the results of finite elements proposed in this work and the analytical and computational results available in the literature. It is also observed that the element based on the Lagrangian formulation is more efficient than the element based on the linear theory regarding the ability to provide a satisfatory response with a less refined mesh

Zoomable user interfaces (ZUIs) have been studied for a long time and many applications are built upon them. Most applications, however, only use two dimensions to express the content. This report presents a solution using all three dimensions where the base features are built as a framework with uniform grids and scene graphs as primary data structures. The purpose of these data structures is to improve performance while maintaining flexibility when creating and handling three-dimensional objects. A 3D-ZUI is able to represent the view of the world and its objects in a more lifelike manner. It is possible to interact with the objects much in the same way as in real world. By developing a prototype framework as well as some example applications, the usefulness of 3D-ZUIs is illustrated. Since the framework relies on abstraction and object-oriented principles it is easy to maintain and extend it as needed. The currently implemented data structures are well motivated for a large scale 3D-ZUI in terms of accelerated collision detection and picking and they also provide a flexible base when developing applications. It is possible to further improve performance of the framework, for example by supporting different types of culling and levels of detail

This thesis is an investigation into the phenomenon which Shozo Ohmori (1921-1997) considered “a peculiar manner of awareness”, and to which he attributed the term ‘fancy’. The objective is to achieve an approximate understanding of Ohmori’s theory of ‘fancy’, as it relates to awareness of entities in three-dimensional space, and the extensions mentioned in his only publication in English: “Beyond Hume’s Fancy” (1974). This objective will be realized by asking three questions. The first question is how we are to understand the demarcation of the different phenomena of awareness which Ohmori identifies. The second question that this thesis asks is what applications that the phenomenon ‘fancy’ mentioned in Ohmori’s account have, as Ohmori saw it. Having answered these questions, I will then make an assessment of another salient consideration: how does Ohmori’s employment of the term ‘fancy’ relate to Hume’s employment of the same term (seeing as the name of Ohmori’s article makes such a reference). As we shall see, Ohmori is attempting to identify a more specific phenomenon than the widely discussed issue of thinking about something that is not currently perceivable in our perceptual field. The third and final question that this thesis asks is whether there are any salient issues with Ohmori’s theory of ‘fancy’ and, if so, whether those issues can be resolved. When we are aware of entities in three-dimensional space, we are subject to various mental processes. Our awareness, seemingly, uses different modes of interpretation and orientation. In other words, our ‘point of view’ (which is something that not only pertains to the use of our visual sensory organs) determines both our place and relation towards other entities. One salient issue when considering the notion of awareness is how and by which order awareness emerges. Impressions, as David Hume would call them, seemingly precede our ideas. Sense-data, as Shozo Ohmori phrased it, is unquestionably inseparable from conceptions. Our conceptions, in turn, seem to inform our perceptions with expectations and predictions of how things are. When we perceive an entity, we are ready to make judgements about its being at this moment. When we see the front of a desk, we are ready to claim awareness of said desk-front as part of a desk (which entails the ontology of a desk, namely, being a three-dimensional construction of a particular variety). In everyday situations we simply speak of such an awareness as ‘perception’ when in actuality, all we see (which constitutes the sense-data or content of a perception) is the front of a desk. It seems we cannot regard our awareness of a desk (a three-dimensional entity) as a perception simpliciter. Of course, by having a notion of what a desk is, our awareness is pregnant with a ‘conception’ in the form of an idea that is informing our awareness of said desk. But our conceptual understanding of the notion of something being a desk is not enough to explain what our awareness of a desk-at-this-moment is. At least, that is what Ohmori thought.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第21327号 / 理博第4423号 / 新制||理||1635(附属図書館) / 京都大学大学院理学研究科数学・数理解析専攻 / (主査)准教授 COLLINS,Benoit Vincent Pierre, 教授 泉 正己, 教授 日野 正訓 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM