Résumé : Dans cette thèse j'ai travaillé sur deux problèmes différents dans le domaine de la Géométrie Algébrique. La première partie de cette thèse consiste dans l'étude de la stabilité des images inverses du fibré tangent de l'espace projectif sur des variétés projectives. La stabilité de ces fibrés est équivalente à celle du noyau du morphisme d'évaluation M associé à un fibré en droites L engendré par ses sections globales. On obtient un résultat optimal dans le cas des courbes projectives et ensuite on utilise ce résultat pour en déduire la stabilité dans le cas des quelques surfaces projectives, notamment K3 et abéliennes. Un second problème que nous abordons est l'étude du lieu fixe d'une involution symplectique d'une variété irréductible holomorphe symplectique de dimension 4 telle que b2 = 23. On montre qu'il y a seulement trois cas possibles pour le nombre des points fixes isolés et des surfaces K3 fixées. On conjecture que seulement un cas soit possible, celui avec 28 points fixes isolés et une surface K3 fixée, et qu'une telle involution ne fixe jamais une surface abélienne. On vérifie cette conjecture dans quelques exemples.

Inom många tillämpningar används konforma avbildningar för att transformera tvådimensionella områden till områden med enklare utseende. Ett exempel på ett sådant område är en kanal av varierande tjocklek begränsad av en kontinuerligt deriverbar kurva. I de tillämpningar som har motiverat detta arbete, är det viktigt att dessa egenskaper bevaras i det område en approximativ konform avbildning producerar, men det är också viktigt att begränsningskurvans riktning kan kontrolleras, särkilt i kanalens båda ändar. Denna avhandling behandlar tre olika metoder för att numeriskt konstruera konforma avbildningar mellan ett enkelt standardområde, företrädesvis det övre halvplanet eller enhetscirkeln, och ett område begränsat av en kontinuerligt deriverbar kurva, där begränsningskurvans riktning kan kontrolleras, exakt eller approximativt. Den första metoden är en utveckling av en idé, först beskriven av Peter Henrici, där en modifierad Schwarz-Christoffel-avbildning avbildar det övre halvplanet konformt på en polygon med rundade hörn. Med utgångspunkt i denna idé skapas en algoritm för att konstruera avbildningar på godtyckliga områden med släta randkurvor. Den andra metoden bygger också den på Schwarz-Christoffel-avbildningen, och utnyttjar det faktum att om enhetscirkeln eller halvplanet avbildas på en polygon kommer ett område Q i det inre av dessa, som till exempel en cirkel med centrum i origo och radie mindre än 1, eller ett område i övre halvplanet begränsat av två strålar, att avbildas på ett område R i det inre av polygonen begränsat av en slät kurva. Vi utvecklar en metod för att hitta ett polygonalt område P, utanför det Omega som man önskar att skapa en avbildning för, sådant att den Schwarz-Christoffel-avbildning som avbildar enhetscirkeln eller halvplanet på P, avbildar Q på Omega. I båda dessa fall används tangentpolygoner för att numeriskt bestämma den önskade avbildningen. Slutligen beskrivs en metod där en av Don Marshalls så kallade zipper-algoritmer används för att skapa en avbildning mellan det övre halvplanet och en godtycklig kanal, begränsad av släta kurvor, som i båda ändar går mot oändligheten som räta parallella linjer. / In many applications, conformal mappings are used to transform two-dimensional regions into simpler ones. One such region for which conformal mappings are needed is a channel bounded by continuously differentiable curves. In the applications that have motivated this work, it is important that the region an approximate conformal mapping produces, has this property, but also that the direction of the curve can be controlled, especially in the ends of the channel. This thesis treats three different methods for numerically constructing conformal mappings between the upper half-plane or unit circle and a region bounded by a continuously differentiable curve, where the direction of the curve in a number of control points is controlled, exact or approximately. The first method is built on an idea by Peter Henrici, where a modified Schwarz-Christoffel mapping maps the upper half-plane conformally on a polygon with rounded corners. His idea is used in an algorithm by which mappings for arbitrary regions, bounded by smooth curves are constructed. The second method uses the fact that a Schwarz-Christoffel mapping from the upper half-plane or unit circle to a polygon maps a region Q inside the half-plane or circle, for example a circle with radius less than 1 or a sector in the half--plane, on a region Omega inside the polygon bounded by a smooth curve. Given such a region Omega, we develop methods to find a suitable outer polygon and corresponding Schwarz-Christoffel mapping that gives a mapping from Q to Omega. Both these methods use the concept of tangent polygons to numerically determine the coefficients in the mappings. Finally, we use one of Don Marshall's zipper algorithms to construct conformal mappings from the upper half--plane to channels bounded by arbitrary smooth curves, with the additional property that they are parallel straight lines when approaching infinity.

Syfte: Syftet med detta arbete är att studera användargränssnittet på ICA-lagrets datorterminal i Västerås och ta fram ett nytt designförslag för det virtuella tangentbordet. Detta för att effektivisera det befintliga användargränssnittet och höja säkerheten för de anställda. Metod: För att nå studiens syfte har ett kvalitativt och tolkande angreppssätt använts, men med kvantitativt element. Intervjuer och mätningar har genomförts med sex respondenter respektive åtta testpersoner. Slutsats: Resultatet visade att det befintliga tangentbordet har brister. Min slutsats är att en redesign av ett virtuellt tangentbord kan minska feltryckningar och knapptryckningar, öka skrivhastigheten och påskynda navigeringen. Detta bidrar till att det blir mindre trafikstopp, irritation och stress. Detta i sin ur påverkar trafiksäkerheten på lagret till det positiva. Det gör även att utbildningstiden kan reduceras då användargränssnittet hela tiden förklarar vad man kan göra och hur.

Šiame darbe nagrinėjama speciali atraminių elementų erdvė – tiesinių elementų erdvė. Šios geometrijos bendrąją tiesinių ir afiniųjų siečių teoriją sukūrė V. Bliznikas. Jis parodė, [5] kaip tiesinės sieties geometrinis objektas indukuoja aukštesniųjų eilių afiniųjų, taip pat tenzorinių siečių objektams. V. Blizniko sukurtais tyrimo metodais dalinai naudojomės ir šiame darbe. Metrinių hiperplokštuminių elementų erdvė yra taip vadinamų normalizuotų erdvių atvejis. Normalizuotos erdvės tai tokios, kuriose apibrėžtos koks nors diferencialinis – geometrinis objektas, kurio invariantai ir sudaro normalizuotos erdvės geometrijos turinį. Tokiais objektais dažnai būna skaliarinė funkcija. (Finslerio ar Kartano erdvės), metrinis tenzorius (tiesinių ar hiperplokštuminių elementų erdvės), afiniosios sieties objektas (afiniosios sieties erdvės) ir pan. Šiame darbe nagrinėjamos metrinių tiesinių elementų erdvės, kurios yra normalizuojamos metrinio tenzoriaus pagalba. Be to, tas tenzorius turi specialią struktūrą (žr. [1]). Ta struktūra charakteringa tuo, kad visuomet tokios erdvės yra Landsbergo erdvių analogai. Darbe pavyko tokioms metrikoms sukonstruoti vidines beveik kompleksines ir beveik sandaugos struktūras, surasti jų integruojamumo sąlygą, kurios dėka metrikos specifika yra kitokia nei analogiškos sąlygos Finslerio erdvėse. Darbas sudarytas ir iš įžangos ir 8 paragrafų. Pirmajame paragrafe dėstomas įvadas į liestinių sluoksniuočių geometriją. Antrajame nagrinėjama šių erdvių... [toliau žr. visą tekstą] / The elements of metric space with a special form of metric are dealt with in the work. It is shown how in such spase linear and affine links are defined with the help of metric tenzor, the ogjects of curvature are founds the existence of the type of metric affine links is proved. It is proved that the metric tenzor induces two parametric almost complex and almost the structures of product, the integration criteria of these structures are found. Keywords: • differentiable manifold • tangent stratified; • linear and affine traceable; • integrated struktures; • structural tensors.

Nous nous intéressons à la modélisation de formes complexes de type structures arborescences, formes lacunaires ou surfaces rugueuses. Ces formes sont intéressantes de par leurs propriétés physiques particulières :objets légers, économie de matière, résistance mécanique, absorption acoustique importante. Les modèles basés sur le concept de la géométrie fractale permettent de générer de telles formes et notamment les formes auto-similaires. A partir des travaux de Barnsley sur les systèmes itérés de fonctions, Tosan et al, ont proposé une extension, Boundary Controled Iterated Funcions Systems (BCIFS) pour contrôler plus facilement les formes et faciliter leur description. Nous nous intéressons aux propriétés différentielles des formes décrites par BCIFS. Nous proposons une définition plus générale d'espace tangent qui permet de caractériser le comportement de cas non-classiquement différentiables.Nous montrons que l'étude du comportement différentiel peut alors se faire simplement par analyse des valeurs propres et vecteurs propres généralisés des opérateurs de subdivision. Il devient alors possible de contrôler ces propriétés différentielles. Nous présentons une application de nos résultats, en proposant une méthode pour construire des raccords entre deux structures définies par des processus de subdivision différents. Cette méthode est appliquée pour la construction d'un raccord entre une surface de subdivision de Doo-Sabin(schéma dual) et une surface de subdivision de Catmull-Clark (schéma primal)

Submitted by Emanuel Varela Cardoso (emanuel.varela@ufcg.edu.br) on 2018-11-12T17:19:37Z No. of bitstreams: 1 CARLOS ANDRÉ CARNEIRO DE OLIVEIRA – DISSERTAÇÃO (PPGMat) 2014.pdf: 2129969 bytes, checksum: 19715b30880dbcde6347a169b0fdbdec (MD5) / Made available in DSpace on 2018-11-12T17:19:37Z (GMT). No. of bitstreams: 1 CARLOS ANDRÉ CARNEIRO DE OLIVEIRA – DISSERTAÇÃO (PPGMat) 2014.pdf: 2129969 bytes, checksum: 19715b30880dbcde6347a169b0fdbdec (MD5) Previous issue date: 2014-04 / Este trabalho apresenta um estudo sobre o ensino da trigonometria no ensino médio, contemplando as recomendações sobre esse conteúdo encontradas nos Parâmetros Curriculares Nacionais e uma breve análise desses conteúdos em alguns dos livros recomendados pelo Guia de Livros Didáticos de Matemática - PNLP 2012. Destacando a formação do conceito de radiano; a extensão das razões trigonométricas seno, cosseno e tangente definidas no triângulo retângulo para as funções Trigonométricas de domínio real, além das demonstrações geométricas das fórmulas da adição e da subtração de arcos das funções seno, cosseno e tangente. Apresenta, também, uma sequência didática, com atividades contemplando os conteúdos destacados acima. As atividades foram elaboradas tendo como referência a teoria da aprendizagem significativa e adaptadas ao uso do software GeoGebra. / This work presents a study on the teaching of trigonometry in high school, in accordance with the recommendations about this subject found in National Curriculum Guidelines (Parâmetros Curriculares Nacionais) and a analysis of the content of some of the books recommended by the Mathematics Textbook Guide - PNLP 2012. It highlight the formation of the concept of radian; the extension of trigonometric ratios sine, cosine and tangent defined in the triangle for Trigonometric functions of real field, in addition to the geometrical proofs of the formula of addition and subtraction arches functions sine, cosine and tangent. It also presents a didactic sequence, with activities covering the highlighted contents above. The activities were developed with reference to the meaningful learning theory and adapted to the use of GeoGebra software.

L’analyse de texture est une composante du traitement d’image qui suscite beaucoup d’intérêt tant les applications qu’elle recouvre sont diverses. En imagerie médicale, les signaux enregistrés sous forme d’images telles que les radiographies de l’os ou les mammographies, présentent une micro-architecture fortement irrégulière qui invite à considérer la formation de ces textures comme la réalisation d’un champ aléatoire. Suite aux travaux précurseurs de Benoit Mandelbrot, de nombreux modèles dérivés du champ brownien fractionnaire ont été proposés pour caractériser l’aspect fractal des images et synthétiser des textures à rugosité prescrite. Ainsi l’estimation des paramètres de ces modèles, a notamment permis de relier la dimension fractale des images à la détection de modifications de la structure osseuse telle qu’on l’observe en cas d’ostéoporose. Plus récemment, d’autres modèles de champs aléatoires, dits anisotropes, ont été utilisés pour décrire des phénomènes présentant des directions privilégiées, et détecter par exemple des anomalies dans les tissus mammaires.Cette thèse porte sur l’élaboration de nouveaux modèles de champs anisotropes, permettant de contrôler localement l’anisotropie des textures. Une première contribution a consisté à définir un champ brownien fractionnaire anisotrope généralisé (GAFBF), et un second modèle basé sur une déformation de champs élémentaires (WAFBF), permettant tous deux de prescrire l’orientation locale de la texture. L’étude de la structure locale de ces champs est menée à l’aide du formalisme des champs tangents. Des procédures de simulation sont mises en oeuvres pour en observer concrètement le comportement, et servir de benchmark à la validation d’outils de détection de l’anisotropie. En effet l’étude de l’orientation locale et de l’anisotropie dans le cadre des textures soulève encore de nombreux problèmes mathématiques, à commencer par la définition rigoureuse de cette orientation. Notre seconde contribution s’inscrit dans cette perspective. En transposant les méthodes de détection de l’orientation basées sur la transformée en ondelettes monogéniques, nous avons été en mesure, pour une vaste classe de champs aléatoires, de définir une notion d’orientation intrinsèque. En particulier l’étude des deux nouveaux modèles de champs anisotropes introduits précédemment, a permis de relier formellement cette notion d’orientation aux paramètres d’anisotropie de ces modèles. Des connexions avec les statistiques directionnelles sont également établies, de façon à caractériser la loi de probabilité des estimateurs d’orientation.Enfin une troisième partie de la thèse est consacrée au problème de la détection de lignes dans les images. Le modèle sous jacent est celui d’une superposition de lignes diffractées (c-a-d convoluées par un noyau de flou) et bruitées, dont il s’agit de retrouver les paramètres de position et d’intensité avec une précision sub-pixel. Nous avons développé dans cet objectif une méthode basée sur le paradigme de la super-résolution. La reformulation du problème en termes d’atomes 1-D a permis de dégager un problème d’optimisation sous contraintes, et de reconstruire ces lignes en atteignant cette précision. Les algorithmes employés pour effectuer la minimisation appartiennent à la famille des algorithmes dits proximaux. La formalisation de ce problème inverse et sa résolution, constituent une preuve de concept ouvrant des perspectives à l’élaboration d’une transformée de Hough revisitée pour la détection ‘continue’ de lignes dans les images. / Texture analysis is a component of image processing which hold the interest in the various applications it covers. In medical imaging, the images recorded such as bone X-rays or mammograms show a highly irregular micro-architecture, which invites to consider these textures formation as a realization of a random field. Following Benoit Mandelbrot’s pioneer work, many models derived from the fractional Brownian field have been proposed to characterize the fractal behavior of images and to synthesize textures with prescribed roughness. Thus, the parameters estimation of these models has made possible to link the fractal dimension of these images to the detection of bone structure alteration as it is observed in the case of osteoporosis. More recently, other models known as anisotropic random fields have been used to describe phenomena with preferred directions, for example for detecting abnormalities in the mammary tissues.This thesis deals with the development of new models of anisotropic fields, allowing to locally control the anisotropy of the textures. A first contribution was to define a generalized anisotropic fractional Brownian field (GAFBF), and a second model based on an elementary field deformation (WAFBF), both allowing to prescribe the local orientation of the texture. The study of the local structure of these fields is carried out using the tangent fields formalism. Simulation procedures are implemented to concretely observe the behavior, and serve as a benchmark for the validation of anisotropy detection tools. Indeed, the investigation of local orientation and anisotropy in the context of textures still raises many mathematical problems, starting with the rigorous definition of this orientation. Our second contribution is in this perspective. By transposing the orientation detection methods based on the monogenic wavelet transform, we have been able, for a wide class of random fields, to define an intrinsic notion of orientation. In particular, the study of the two new models of anisotropic fields introduced previously allowed to formally link this notion of orientation with the anisotropy parameters of these models. Connections with directional statistics are also established, in order to characterize the probability distribution of orientation estimators.Finally, a third part of this thesis was devoted to the problem of the lines detection in images. The underlying model is that of a superposition of diffracted lines (i.e, convoluted by a blur kernel) with presence of noise, whose position and intensity parameters must be recovered with sub-pixel precision. We have developed a method based on the super-resolution paradigm. The reformulation of the problem in the framework of 1-D atoms lead to an optimization problem under constraints, and enables to reconstruct these lines by reaching this precision. The algorithms used to perform the minimization belong to the family of algorithms known as proximal algorithms. The modelization and the resolution of this inverse problem, provides a proof of concept opening perspectives to the development of a revised Hough transform for the continuous detection of lines in images.

abstract: Microwave properties of low-loss commercial dielectric materials are optimized by adding transition-metal dopants or alloying agents (i.e. Ni, Co, Mn) to tune the temperature coefficient of resonant frequency (τf) to zero. This occurs as a result of the temperature dependence of dielectric constant offsetting the thermal expansion. At cryogenic temperatures, the microwave loss in these dielectric materials is dominated by electron paramagnetic resonance (EPR) loss, which results from the spin-excitations of d-shell electron spins in exchange-coupled clusters. We show that the origin of the observed magnetically-induced shifts in the dielectric resonator frequency originates from the same mechanism, as described by the Kramers-Kronig relations. The temperature coefficient of resonator frequency, τf, is related to three material parameters according to the equation, τf = - (½ τε + ½ τµ + αL), where τε, τµ, and αL are the temperature coefficient of dielectric constant, magnetic permeability, and lattice constant, respectively. Each of these parameters for dielectric materials of interest are measured experimentally. These results, in combination with density functional simulations, developed a much improved understanding of the fundamental mechanisms responsible for τf. The same experimental methods have been used to characterize in-situ the physical nature and concentration of performance-degrading point defects in the dielectrics of superconducting planar microwave resonators. / Dissertation/Thesis / Doctoral Dissertation Materials Science and Engineering 2016

Submitted by Viviane Lima da Cunha (viviane@biblioteca.ufpb.br) on 2015-06-02T14:42:10Z No. of bitstreams: 1 arquivototal.pdf: 4771282 bytes, checksum: 54ad9700566c303ef32a4f565e89ee2c (MD5) / Approved for entry into archive by Viviane Lima da Cunha (viviane@biblioteca.ufpb.br) on 2015-06-03T22:27:07Z (GMT) No. of bitstreams: 1 arquivototal.pdf: 4771282 bytes, checksum: 54ad9700566c303ef32a4f565e89ee2c (MD5) / Made available in DSpace on 2015-06-03T22:27:07Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 4771282 bytes, checksum: 54ad9700566c303ef32a4f565e89ee2c (MD5) Previous issue date: 2014-07-04 / In this work, we study the principles of the theory of plane curves, within the context of high school / Neste trabalho estudamos os princípios da teoria das curvas planas, tendo em mente, estudantes do ensino médio. Aqui, é proposta uma introdução ao Cálculo Diferencial e Integral àqueles estudantes, e em seguida um estudo sobre a teoria das curvas, onde alguns exemplos clássicos são apresentados, bem como, conceitos como vetor tangente, área e comprimento de curvas são discutidos.

Este trabalho descreve os métodos e os resultados encontrados a partir da implementação de métodos estáticos para análise da estabilidade de tensão em sistemas elétricos de potência. A determinação da margem de estabilidade de tensão foi feita através do cálculo do menor valor singular da matriz jacobiana associada às equações de fluxo de carga, comumente utilizado como índice estático de colapso de tensão. As não linearidades e descontinuidades relatadas nas referências estudadas e encontradas nos testes realizados, levaram-nos a propor o uso da razão entre o menor e o maior valores singulares da mesma matriz jacobiana, na expectativa de que este índice tivesse um comportamento menos instável do que o menor valor singular, o que não foi confirmado nos testes realizados. Identifica-se também as regiões do sistema elétrico mais afetadas pela instabilidade, o que é feito através da determinação da barra crítica do sistema e da classificação das barras de carga em ilhas de controle de tensão. A barra crítica é identificada através do cálculo do vetor tangente do sistema, conforme proposto nas referências citadas no trabalho. Como alternativa ao vetor tangente para a identificação da barra crítica, propôs-se usar o vetor singular à direita associado ao menor valor singular da matriz jacobiana. A comparação da capacidade de identificação da barra crítica por esses dois vetores mostrou uma clara vantagem do uso do vetor tangente. A rotina para identificação das ilhas de controle de tensão foi adaptada a partir de um método desenvolvido para a análise de coerência em barras de carga, e os resultados encontrados foram bastante satisfatórios. Os métodos implementados foram testados em diversas situações, com o objetivo de se analisar os efeitos dos modelos de carga ZIP com elevadas parcelas de impedância constante, dos limitadores de potência reativa dos geradores e da repartição do incremento da carga de potência ativa entre os geradores. / This work describes the methods and results got from the implementation of static methods for power systems voltage stability analisys. The power system voltage stability margin was predicted by the smallest load flow jacobian\'s singular value, commonly used as a prediction index to voltage stability. lt is investigated the use of ratio of the smallest single value by the biggest one as voltage colapse index, assuming that it\'s less unstable than the singular value itself, specialy near the collapse point. The results presented shown a clear advantage of using the smallest singular value instead of this singular value rate. The identification of the system\'s regions affected by the voltage drop is made by the tangent vector and by the voltage island identification method proposed on this work. Is compared the ability to identify system\'s critical bus by the tangent vector and right singular vetor of the smallest jacobian\'s singular value. In this case, tests results show the superiority of tangent vector. All the simulations presented are compared to allow the analysis of the voltage dependents load models (with high percentual of constant impedances), reactive limiters and generators load sharing efects over the smallest singular value, the rate of the smallest single value by the biggest one, voltage island classification and the critical bus identification.