The distinct element method (DEM) is a useful tool in rock engineering to model jointed rock masses. To simulate a jointed rock mass realistically, the main challenge is to be able to capture its complex geometry which consists of blocks with various shapes and sizes, and to model the interactions between these blocks. The main contribution of this thesis is the development of novel algorithms in the DEM to model jointed rock masses, namely rock slicing procedures for block generation, and algorithms for contact detection between polygonal blocks in 2-D or polyhedral blocks in 3-D. These algorithms make use of convex optimisation techniques, for which there exist efficient solution procedures. They do not rely on conventional vertex-edge-face hierarchical data structures and tedious housekeeping algorithms. The algorithms have been verified against analytical and numerical solutions, as well as validated against experimental results published in the literature. Among those, the results of DEM simulations were compared against the experimental model tests and numerical simulations of jointed beams carried out by Talesnick et al. (2007) and Tsesarsky & Talesnick (2007) respectively. Emphasis was placed on modelling the stiffness of the block interfaces accurately, and this was accomplished by reinterpreting the laboratory data published by the investigators. The capabilities of the numerical tools are also examined and demonstrated in areas for which the DEM has found practical application. A substantial fraction of this thesis is devoted to illustrating how these tools can assist the engineer in designing support systems; for example, designing the length and spacing of rock bolts and the lining thickness for a tunnel. Algorithms to model rock bolt and lining support were implemented for this purpose. Interesting comparisons with elastic solutions for supported openings were obtained. Further, it is shown that the relative benefit of introducing more rock bolts or thicker lining can be evaluated using the numerical tools with the aid of an interaction diagram. In the final part of this thesis, the case history of the 1963 Vaiont rock slide in Italy is studied. The 2-D analyses led to useful insights concerning the influence of the reservoir water level, the rock mass strength and deformability, and the slide surface shear stiffness. 3-D analyses were undertaken to investigate the influence of the eastern boundary of the slope, and interesting insights were obtained concerning the slope kinematics. Overall, the case study shows that the tools are capable of modelling problems with specific physical and geometrical detail in both 2-D and 3-D.

Dans la première partie de ce mémoire, on s’attache à l’obtention d’Inégalités de Carleman elliptiques pour des opérateurs d’ordre deux au bord pour des conditions dites de Ventcel. Dans une seconde partie, on démontre une Inégalité adaptée aux multi-interfaces, pour des opérateurs elliptiques d’ordre quelconque, sous la condition classique de sous-ellipticité de Hörmander, ainsi que sous une condition de compatibilité entre les opérateurs sur la multi-interface et l’intérieur, dite de recouvrement. Cette condition généralise la condition de Lopatinskii. Enfin, dans une troisième partie, on s’intéresse à la contrôlabilté de l’équation de la chaleur et la stabilisation faible de l’équation des ondes dans des domaines polygonaux. / In the first part of this thesis, we derive elliptic Carleman estimates for second-order operators with Ventcel boundary conditions. In the second part, we prove a proper estimate near multi-interfaces for elliptic operatorsof any order, under the classical sub-ellipticity condition of Hörmander and under a compatibility condition between the operators in the interior and at the multi-interface, called the covering condition. This condition is a generalization of the well-known Lopatinskii condition. Finally, in the third part, we focus on controllability properties of the heat equation, and stabilization properties of the wave equation for polygonal domains, with mixed boundary conditions.

Dans cette thèse, nous nous intéressons à l’étude des courbes discrètes bruitées qui correspondent aux contours d’objets dans des images. Nous avons proposé plusieurs outils permettant de les analyser. Les points dominants (points dont l’estimation de la courbure est localement maximale) jouent un rôle très important dans la reconnaissance de formes et, nous avons développé une méthode non heuristique, rapide et fiable pour les détecter dans une courbe discrète. Cette méthode est une amélioration d’une méthode existante introduite par Nguyen et al. La nouvelle méthode consiste à calculer une mesure d’angle. Nous avons proposé aussi deux approches pour la simplification polygonale : une méthode automatique minimisant, et une autre fixant le nombre de sommets du polygone résultant. Ensuite, nous avons introduit un nouvel outil géométrique, nommé couverture tangentielle adaptative (ATC), reposant sur la détection des épaisseurs significatives introduites par Kerautret et al. Ces épaisseurs calculées en chaque point du contour à analyser, permettent d’estimer localement le niveau de bruit. Dans ce contexte notre algorithme de construction de la couverture tangentielle adaptative prend en considération les différents niveaux de bruits présents dans la courbe à étudier et ne nécessite pas de paramètre. Deux applications de l’ATC sont proposées en analyse d’images : d’une part la décomposition des contours d’une forme dans une image en arcs et en segments de droite et d’autre part, dans le cadre d’un projet avec une université d’Inde, autour du langage des signes et la reconnaissance des gestes de la main. Premièrement, la méthode de décomposition des courbes discrètes en arcs et en segments de droite est basée sur deux outils : la détection de points dominants en utilisant la couverture tangentielle adaptative et la représentation dans l’espace des tangentes du polygone, issue des points dominants détectés. Les expériences montrent la robustesse de la méthode w.r.t. le bruit. Deuxièmement, à partir des contours des mains extraits d’images prises par une Kinect, nous proposons différents descripteurs reposant sur des points dominants sélectionnés du contour des formes dans les images. Les descripteurs proposés, qui sont une combinaison entre descripteurs statistiques et descripteurs géométriques, sont efficaces et conviennent à la reconnaissance de gestes / In this thesis, we are interested in the study of noisy discrete curves that correspond to the contours of objects in images. We have proposed several tools to analyze them. The dominant points (points whose curvature estimation is locally maximal) play a very important role in pattern recognition and we have developed a non-heuristic, fast and reliable method to detect them in a discrete curve. This method is an improvement of an existing method introduced by Nguyen et al. The new method consists in calculating a measure of angle. We have also proposed two approaches for polygonal simplification: an automatic method minimizing, and another fixing the vertex number of the resulting polygon. Then we proposed a new geometric tool, called adaptive tangential cover ATC, based on the detection of meaningful thickness introduced by Kerautret et al. These thicknesses are calculated at each point of the contours allow to locally estimate the noise level. In this context our construction algorithm of adaptive tangential cover takes into account the different levels of noise present in the curve to be studied and does not require a parameter. Two applications of ATC in image analysis are proposed: on the one hand the decomposition of the contours of a shape in an image into arcs and right segments and on the other hand, within the framework of a project with an Indian university about the sign language and recognition of hand gestures. Firstly, the method to decompose discrete curves into arcs and straight segments is based on two tools: dominant point detection using adaptive tangential cover and tangent space representation of the polygon issued from detected dominant points. The experiments demonstrate the robustness of the method w.r.t. noise. Secondly, from the outlines of the hands extracted from images taken by a Kinect, we propose several descriptors from the selected dominant points computed from the adaptive tangential cover. The proposed descriptors, which are a combination of statistical descriptors and geometrical descriptors, are effective and suitable for gesture recognition

Music mood recognition by machine continues to attract attention from both academia and industry. This thesis explores the hypothesis that the music emotion problem is circular, and is a primary step in determining the efficacy of circular regression as a machine learning method for automatic music mood recognition. This hypothesis is tested through experiments conducted using instances of the two commonly accepted models of affect used in machine learning (categorical and two-dimensional), as well as on an original circular model proposed by the author. Polygonal approximations of circular regression are proposed as a practical way to investigate whether the circularity of the annotations can be exploited. An original dataset assembled and annotated for the models is also presented. Next, the architecture and implementation choices of all three models are given, with an emphasis on the new polygonal approximations of circular regression. Experiments with different polygons demonstrate consistent and in some cases significant improvements over the categorical model on a dataset containing ambiguous extracts (ones for which the human annotators did not fully agree upon). Through a comprehensive analysis of the results, errors and inconsistencies observed, evidence is provided that mood recognition can be improved if approached as a circular problem. Finally, a proposed multi-tagging strategy based on the circular predictions is put forward as a pragmatic method to automatically annotate music based on the circular model. / Graduate / 0984 / 0800 / 0413 / zazz101@hotmail.com

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Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-07-06T13:51:44Z No. of bitstreams: 1 THICIANY MATSUDO IWANO - DISSERTAÇÃO PPGMAT 2005..pdf: 3751075 bytes, checksum: 2aaae3fdd115cd9f6f4b653f522d94c8 (MD5) / Made available in DSpace on 2018-07-06T13:51:44Z (GMT). No. of bitstreams: 1 THICIANY MATSUDO IWANO - DISSERTAÇÃO PPGMAT 2005..pdf: 3751075 bytes, checksum: 2aaae3fdd115cd9f6f4b653f522d94c8 (MD5) Previous issue date: 2005-10 / Neste trabalho apresentamos um estudo das principais técnicas de geração de malhas poligonais, a partir de superfícies descritas matematicamente por funções implícitas,isto é, superfícies definidas pelo conjunto S = f−1(0) = {X ∈ R3 | f(X) = 0}, onde f : R3 → R e f é, pelo menos, de classe C2. Mostramos um método para obter as curvaturas gaussiana e média dessas superfícies a partir do vetor ∇f para cada ponto de S. Abordamos questões como a preservação de características geométricas e topológicas do objeto gráfico. Dentre os métodos estudados, ressaltamos o algoritmo Marching Triangles, que gera uma malha a partir de um ponto arbitrário p sobre a superfície S e um referencial local, usando a abordagem do avanço de frentes. Em sua implementação, usamos o raio de curvatura, calculado a partir da curvatura normal máxima absoluta da superfície em cada ponto p pertencente a S, para adaptar o comprimento das arestas da malha triangular à geometria local da superfície S / In this work we present a study about the main techniques of surfaces meshes generation, described by implicit functions, that is, surfaces defined by the set S = f−1(0) = {X ∈ R3 | f(X) = 0}, where f : R3 → R and f is, at least, C2. We discuss aspects involving his preservation of graphic object’s geometry and topology. As special method we cite the Marching Triangles that generates a mesh starting from an arbitrary point p on surface S and a local referencial, using advancing fronts approach. In our implementation, we use the radius of curvature, calculated from surface’s absolute maximum normal curvature in each point p in S and the triangular mesh, to adapt the edges length of the mesh to the local geometry.

Submitted by Kamila Costa (kamilavasconceloscosta@gmail.com) on 2015-08-07T13:59:57Z No. of bitstreams: 1 Dissertacao - Erivaldo R. Santana.pdf: 3301648 bytes, checksum: f3e68eae0be26f8d67132dc1bd792d18 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-08-07T14:09:31Z (GMT) No. of bitstreams: 1 Dissertacao - Erivaldo R. Santana.pdf: 3301648 bytes, checksum: f3e68eae0be26f8d67132dc1bd792d18 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-08-07T14:11:00Z (GMT) No. of bitstreams: 1 Dissertacao - Erivaldo R. Santana.pdf: 3301648 bytes, checksum: f3e68eae0be26f8d67132dc1bd792d18 (MD5) / Made available in DSpace on 2015-08-07T14:11:00Z (GMT). No. of bitstreams: 1 Dissertacao - Erivaldo R. Santana.pdf: 3301648 bytes, checksum: f3e68eae0be26f8d67132dc1bd792d18 (MD5) Previous issue date: 2015-04-30 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This work bears the purpose of setting up the course of the circle quadrature solution attempts, as well as to mention its influences, contributions for the mathematics development until now and to incentive the geometry dynamics use. In it we produce a possible explanation of how geometry has been created besides of a brief study on the number followed of the production GeoGebra software, the too we have utilized to build up the figures and the work implementations. We will utilize the areas equivalence based on Euclides elements to solve an initial problem: that of constructing a quadrilateral equivalent to a given pentagon and, for such, it will be necessary the demonstration of some propositions. We will utilize the square to relate its areas with those of the polygonal figures through the âquadratureâ method. With such we will execute the rectangle, triangle, pentagon quadrature, and that of the convex n sides polygon. We will utilize Pitagoras theorem to sum up the squares areas by bringing up brief comments about its use. Afterward this method will also the utilized in the attempt of squaring the curvelin figures such as the circle which has later on originated the problem of the circle quadrature. For explain such a problem we will utilize the geometric construction along with the demonstration of two methods for obtaining the circle quadrature and its respective results and comparisons. In the sequence, we will know what the are constructive numbers, algebraic and transcendent, which will enable us to reach to a classification of the number and its relation to the circle quadrature problem, reaching out the answer to our problem. While defining the geometrical average we will demonstrate how to obtain some quadrature utilized in such an average in the proposed activities. In other words, we can say that this work aims to produce the circle quadrature problem, the investigation of the methods developed by mathematicians for the solution of this problem in the course of history and, finally, an ascertainment on the answer these methods point us. / Este trabalho tem o intuito de traçar o percurso das tentativas de solução da quadratura do círculo, bem como citar suas influências, contribuições para o desenvolvimento da matemática até os dias de hoje e incentivar o uso da geometria dinâmica. Nele apresentamos uma possível explicação de como surgiu a geometria, além de um breve estudo sobre o número , seguido de uma apresentação do software GeoGebra, ferramenta que utilizamos para construção das figuras e das implementações do trabalho. Utilizaremos a equivalência de áreas baseada na obra dos elementos de Euclides para resolvermos um problema inicial: o de construir um quadrilátero equivalente a um pentágono dado e, para isso, será necessária a demonstração de algumas proposições. Utilizaremos o quadrado para relacionarmos a sua área com as das demais figuras poligonais pelo método da "quadratura". Com isso, executaremos as quadraturas do retângulo, triângulo, pentágono e do polígono convexo de n lados. Utilizaremos o Teorema de Pitágoras para somarmos áreas de quadrados, tecendo breves comentários acerca de seu uso. Posteriormente esse método também foi utilizado na tentativa de quadrar-se áreas de figuras curvilíneas, como o círculo, no que mais tarde originou o problema da quadratura do círculo. Para a exposição deste problema mostraremos a construção geométrica e a demonstração de dois métodos para obtermos a quadratura do círculo e seus respectivos resultados e comparações. Em seguida, definiremos o que são números construtíveis, algébricos e transcendentes, o que nos possibilitará chegar a uma classificação do número e sua relação com o problema da quadratura do círculo, chegando à resposta do nosso problema. Ao definirmos a média geométrica, mostraremos como obter algumas quadraturas utilizando essa média nas atividades propostas. Em outras palavras, podemos dizer que este trabalho objetiva apresentar o problema da quadratura do círculo, a investigação de métodos desenvolvidos por matemáticos para resolução deste problema ao longo da história e finalmente uma constatação acerca da resposta que estes métodos nos apontam.

This thesis deals with the concept of virtual reality, its history, present-day possibilities and available devices and technologies for virtual reality and ways of creating assets such as models, textures and animations for virtual reality applications. The practical part of this work deals with design and creation of three-dimensional models, textures, animations and environment for use in interactive application in virtual reality and also with design and creation of such application to demonstrate their use.

This thesis is focused to problems of automatic generation of border surface for cranial implant. This document includes description of 3D modeling human tissue, followed with issue of cranial implant. Next it includes possible perspectives of solving automatic generation problems for implant border. Second half of this document is focused to implementation of tool for automatic generation of border surface. Final part deals with results of work with this tool.

This document discusses a problem of tooth detection on jaw 3D polygonal model. It describes known methods that can be used to reach expected results, such as their advantages and disadvantages. Considering this, I choose one solution that is closely described with all theory needed for its implementation.