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Cao, Li, and 曹力. "Interactive network rendering based on textured depth map re-projection." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B48199448.
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Network Rendering is an important problem in computer graphics and visualization
applications. Reduction of the data needed for transmission over the network can greatly
improve the performance. Many methods, such as mesh simplification, image tiling, level
of detail and user action prediction, have been developed to solve this problem..
In this thesis, a new approach tackling the problem has been explored. A textured depth
map (called Terrain Instance Map, TIM) based on re-projection method is introduced
to render highly detailed terrain models. TIMs are created by a rendering server with
a specified viewpoint from the client. Re-projection of the textured depth map in TIM
can satisfy user requests for rendering in the client. In order to achieve an interactive
frame rate at the client side and to reduce the workload of the server, a client side
cache system is designed to reconstruct in-between screen shots from previously rendered
results sparsely provided by the server. Experimental results show that the proposed
method is effective for network rendering.
By changing the projection plane and splitting the viewport into small blocks, Screen
Instance Map (SIM) is developed for arbitrary models with or without texture. The
implemented network rendering system can satisfy interactive rendering in the client.
Compared with existing methods, the new method needs virtually no additional storage
space for the server and supports a wide range of inputs other than meshes.
Finally, computation of camera frames for the virtual camera control is studied as a part
of the network rendering system. A new Single Reflection method (SRM) to solve the
rotation-minimizing directed frame (RMDF) problem is proposed and it is shown that
the method is more robust and twice as fast than the existing method. Based on the
new method, a simple and effective scheme for camera frames interpolation is devised.
The methods and concepts introduced in this thesis are useful and effective for interactive
network rendering. The TIM and SIM methods can be applied to network rendering for models with or without texture. The SRM method is essential for real-time camera
frame computation and its extension can be applied to user interaction for viewing
virtual environments.published_or_final_version
Computer Science
Doctoral
Doctor of Philosophy
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Zhang, Jiaqi. "Accelerating and Predicting Map Projections with CUDA and MLP." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1523394255002174.
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Tjung, Jie Wen. "Projection, design, and representation of curves on B-spline surfaces /." This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-03042009-040805/.
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Tjung, Jie Wen. "Projection, design, and representation of curves on B-spline surfaces." Thesis, Virginia Tech, 1992. http://hdl.handle.net/10919/41412.
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Chavez, Daniel. "Parallelizing Map Projection of Raster Data on Multi-core CPU and GPU Parallel Programming Frameworks." Thesis, KTH, Skolan för datavetenskap och kommunikation (CSC), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-190883.
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Map projections lie at the core of geographic information systems and numerous projections are used today. The reprojection between different map projections is recurring in a geographic information system and it can be parallelized with multi-core CPUs and GPUs. This thesis implements a parallel analytic reprojection algorithm of raster data in C/C++ with the parallel programming frameworks Pthreads, C++11 STL threads, OpenMP, Intel TBB, CUDA and OpenCL. The thesis compares the execution times from the different implementations on small, medium and large raster data sets, where OpenMP had the best speedup of 6, 6.2 and 5.5, respectively. Meanwhile, the GPU implementations were 293 % faster than the fastest CPU implementations, where profiling shows that the CPU implementations spend most time on trigonometry functions. The results show that reprojection algorithm is well suited for the GPU, while OpenMP and Intel TBB are the fastest of the CPU frameworks.Kartprojektioner är en central del av geografiska informationssystem och en otalig mängd av kartprojektioner används idag. Omprojiceringen mellan olika kartprojektioner sker regelbundet i ett geografiskt informationssystem och den kan parallelliseras med flerkärniga CPU:er och GPU:er. Denna masteruppsats implementerar en parallel och analytisk omprojicering av rasterdata i C/C++ med ramverken Pthreads, C++11 STL threads, OpenMP, Intel TBB, CUDA och OpenCL. Uppsatsen jämför de olika implementationernas exekveringstider på tre rasterdata av varierande storlek, där OpenMP hade bäst speedup på 6, 6.2 och 5.5. GPU-implementationerna var 293 % snabbare än de snabbaste CPU-implementationerna, där profileringen visar att de senare spenderade mest tid på trigonometriska funktioner. Resultaten visar att GPU:n är bäst lämpad för omprojicering av rasterdata, medan OpenMP är den snabbaste inom CPU ramverken.
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Kalčík, Vojtěch. "Implementace GIS nástroje pro mobilní počítačová zařízení." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2013. http://www.nusl.cz/ntk/nusl-235465.
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This master's thesis with draft of GIS tool for mobile platforms. The resulting program will be adapted for collection of geographic data in the field. The program will work with standard file formats for GIS. High emphasis is put on the control, which is particular for mobile devices with capacitive display. The program will be designed for both smartphone and tablet. Explanation of the mapping principle and description of geographic information systems are also parts of the thesis.
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Gurgel, Abilio Castro. "Mercator e sua contribuição à cartografia e ao estudo dos mapas." Pontifícia Universidade Católica de São Paulo, 2012. https://tede2.pucsp.br/handle/handle/13265.
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Previous issue date: 2012-05-14The primary source of this research is Gerardus Mercator, born in 1512 on Rupelmond Villa, Flanders area, now Belgium, and deceased in Duisburg, on Cleves dukedom, current in western Germany, in 1594. Mercator, besides a cartographer, was calligrapher, carver and engraver in copper plates (used for graphic printing), manufacturer of scientific instruments (compasses, rulers and squares), of terrestrial and celestial globes and, also, map editor. However, is the world map of 1569, in a map projection became different from everything that had in the moment and remained for more than 400 years as standard maps that will be in this Gerardus Mercator s universe the central focus of this work. The chapter 1 of the research contains a brief explanation about the origin of maps and the explanation of geography in antiquity Greek to may understand the basis on which the renaissance cartographers, including Mercator, could resume studies of maps and cartographic projections. The chapter 2 studies Mercator and his social, political and economical contexts, besides the specific Flanders politic, the religious question with the rise of Protestant Reformation and how all this situation was connected with the life trajectory of the cartographer. The chapter 3 will analyze specifically his most famous map of 1569, its finality, purposes, consequences and how it was elaborated. It will be shown what were the differential in relation to other maps made at the time and, mainly, how the Ptolemaic maps was resumed by Mercator
A fonte primária desta pesquisa é Gerardus Mercator, nascido em 1512 na vila de Rupelmonde, região de Flandres, atual Bélgica, e falecido em Duisburg, no Ducado de Cléves, no oeste da atual Alemanha, em 1594. Mercator, além de cartógrafo, era calígrafo, entalhador e gravador em placas de cobre (usadas em impressão gráfica), construtor de instrumentos científicos (compassos, réguas e esquadros), de globos terrestres e celestiais e, também, editor de mapas. Entretanto, é o mapa-múndi de 1569, em uma projeção cartográfica diferenciada de tudo que havia no momento e que permaneceu por mais de 400 anos como padrão para mapas, que será, nesse universo de Gerardus Mercator, o foco central deste trabalho. O capítulo 1 da pesquisa conterá uma breve explicação sobre a origem dos mapas e a explanação da geografia na Antiguidade grega para que se possa entender qual foi a base com a qual os cartógrafos renascentistas, inclusive Mercator, puderam reiniciar o estudo dos mapas e das projeções cartográficas. O capítulo 2 estudará Mercator e seu contexto social, político e econômico, além da política específica de Flandres, da questão religiosa com a ascensão da reforma protestante e como toda essa situação esteve ligada à trajetória de vida do cartógrafo. O capítulo 3 analisará especificamente o famoso mapa de 1569, sua finalidade, objetivos, consequências e como foi elaborado. Mostrar-se-ão quais foram os diferenciais em relação aos outros mapas feitos na época e, principalmente, como os mapas ptolomaicos foram retomados por Mercator
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Mariani, Louise-Laure. "Biosensor imaging of dopamine and glutamate signaling in striatal projection neurons in a mouse model of dopamine depletion." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS511.
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La maladie de Parkinson (MP) est la seconde maladie neurodégénérative la plus fréquente. Il n’y a pas de traitement curatif de la maladie. Les traitements symptomatiques s’appuient principalement sur le remplacement de la dopamine (DA). Le traitement par L-DOPA, particulièrement efficace initialement, se complique à long terme par des fluctuations et dyskinésies. Les mécanismes de la plasticité striatale anormale sous-tendant l’apparition de ces dyskinésies sont mal compris. Le but de ce projet était d’identifier les anomalies des voies de signalisation dans les neurones de projection du striatum en l’absence de DA. Nous avons utilisé chez des souris avec lésion ou non des neurones DA par la 6-OHDA, des biosenseurs permettant l’étude de voies de signalisation en imagerie cellulaire multiphotonique de neurones vivants dans des tranches corticostriatales. Nous avons d’abord mis au point ce modèle combinant injection stéréotaxique de toxine et de vecteur viral chez des souris adultes. Dans certaines expériences nous avons étudié spécifiquement les réponses des neurones de projection striataux des voies directe (NPSd) ou indirecte (NPSi) en utilisant des biosenseurs activés par la recombinase Cre et des lignées transgéniques exprimant spécifiquement cette enzyme dans l’une ou l’autre population. Nous avons utilisé des biosenseurs FRET pour mesurer l’activité de la kinase dépendante de l’AMPc (PKA, sonde AKAR3) ou ERK (extracellular signal-regulated kinase, sonde EKAR-EV) et le senseur calcique GcAMP6S pour le Ca2+ libre cytosolique avec une bonne résolution spatiale et temporelle. Nous avons modulé pharmacologiquement les récepteurs de la DA, du glutamate et de l’adénosine, ainsi que les activités des kinases et phosphodiestérases. Nous avons observé que la lésion augmentait les réponses ERK à la stimulation des récepteurs D1 de la DA dans les NPSd. Nous avons montré une augmentation des réponses PKA dans ces neurones pouvant être liée à une augmentation de la protéine G stimulatrice d’adénylyle cyclase, Gαolf, ainsi qu’à une inhibition des phosphodiestérases. L’imagerie calcique a mis en évidence une augmentation de l’activité spontanée des NPSd et, de manière inattendue, de la sensibilité à la stimulation des récepteurs AMPA du glutamate des NPSi. En conclusion notre travail utilise pour la première fois l’imagerie biphotonique par biosenseurs dans le striatum dépourvu de DA de souris adulte. Il met en évidence des déficits multiples et distincts de la signalisation dans les deux populations de neurones de projection du striatum et suggère des mécanismes possibles de ces altérationsParkinson’s disease (PD) is the second most common neurodegenerative disorder after Alzheimer’s disease. There is currently no cure for PD. Symptomatic drug therapy essentially relies on dopamine (DA) replacement therapy. The spectacular antiparkinsonian effect of levodopa in PD is however hampered by long-term complications, motor fluctuations and dyskinesia in all patients at some time during the disease course. The mechanisms of the maladaptive striatal plasticity leading to dyskinesia are not well understood. The aim of this project was to identify the dysregulations of signaling pathways in striatal projection neurons (SPN) in the absence of dopamine. We used a mouse model of lesion of DA neurons with 6-OHDA and virally transduced biosensors to monitor signaling pathways in live neurons with two-photon imaging of corticostriatal slices. We focused our attention on extracellular signal-regulated kinase (ERK), cAMP-dependent protein kinase (PKA) and Ca2+ which are known to be altered in the absence of DA. We first set up a reliable experimental model in adult mice, successfully combining 6-OHDA and viral vector in the same unilateral stereotactic injection into the dorsal striatum. In some experiments we targeted the biosensor expression to specific neuronal populations using Cre-dependent “flexed” biosensors. We used mice expressing Cre under the control of the D1 DA receptor (D1R) promoter to target specifically striatal projection neurons of the direct pathway (dSPNs) or the adenosine A2A receptor (A2AR) to target SPNs of the indirect pathway (iSPNs). We used fluorescence resonance energy transfer (FRET)-based biosensors EKAR-EV and AKAR-3 to monitor ERK and PKA activities, respectively. We also monitored cytosolic free Ca2+ with the genetically encoded calcium indicator GCaMP6S. We used pharmacological tools to modulate glutamate, DA, and adenosine receptors as well as phosphodiesterases (PDE) and kinases activities. We observed that the DA lesion increased ERK responsiveness to stimulation of D1R. Since ERK activation depends on both cAMP and Ca2+ signals, we then investigated these two pathways. We observed an increased activation of PKA in response to D1R but not A2AR. We explored the mechanism of this increased sensitivity using mice deficient for Gαolf, the G protein that couples striatal receptors to adenylyl cyclase. We provided evidence that increased levels of Gαolf contributed to enhanced D1 responses after 6-OHDA lesions and identified a deficit in PDE activity in D1 neurons that was likely to amplify this effect. By monitoring Ca2+ signals we showed an increased spontaneous activity of D1 neurons in lesioned mice. However, unexpectedly the Ca2+ responses to stimulation of AMPA glutamate receptors were increased in iSPNs and not dSPNs. In conclusion, our work using for the first time 2-photon biosensor imaging in the DA-depleted striatum of adult mice confirms and extends previous observations on signaling dysregulations in the absence of DA. It reveals distinct cell type-specific alterations of cAMP, Ca2+ and ERK responses in the two populations of SPNs and suggests possible mechanisms for these alterations
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Larvy, delariviere Ulysse. "Orientation automatique de carte d'environement autour d'une scene locale." Thesis, Reims, 2019. http://www.theses.fr/2019REIMS024.
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Dans cette thèse, nous avons présentons une méthode pour orienter automatiquement une carte d'environnement avec une scène locale.Dans la littérature, de nombreuses méthodes ont besoin d'orienter la carte d'environement pour obtenir une cohérence avec une scène locale. Cette orientation est dans la majorité descas effectuée de manière manuelle par un utilisateur. Nous présentons une méthode pour recaler automatiquement un carte d'environement avec une scène locale. Une caractéristique de notre approche est que nous n'avons pas besoin de créer un modèle 3D complet de la scène locale, ni d'interaction avec l'utilisateur. De plus, nous faisons que de simples hypothèses.Nous proposons un pipeline pour créer une représentation virtuelle de la scène en utilisant nos données d'entrée. Cette représentation comprend la scène globale représentée par la carte d'environement et la scène locale représentée par un objet de référence et son ombre.En utilisant la connaissance de la position de la source lumineuse principale sur la carte d'environnement, nous pouvons simuler l'éclairage et projeter une ombre sur le sol. Il est alors possible de comparer la forme de l'ombre calculée avec celle de l'ombre d'entrée pour récupérer la position correcte de la source lumineuse principale. L'orientation finale de la carte d'environement est directement liée à la position de cette source lumineuse principale.Nous fournissons une évaluation de l'approche proposée en calculant deux métriques qui comparent notre estimation d'angle avec les directions réelles au sol. Notre estimation d'orientation montre que notre méthode récupère une orientation de carte d'environement correcteIn this thesis, we have presented a method to register an environment map with a local scene automatically.In the literature, many methods need to orient the environmental map to be coherent with a local scene. This orientation is mostly done manually by a user. We present a method to register an environment map with a local scene automatically. A characteristic of our approach is that we do not need to create a complete 3D model of the local scene or have interaction with the user. Moreover, we are making simple assumptions.We propose a pipeline to create a virtual representation of the scene using our input data. This representation includes the global scene represented by the environment map and the local scene represented by a reference object and its shadow.By using the knowledge of the position of the main light source on the environment map, we can simulate the lighting and project a computed shadow on the ground. It is possible to compare the computed shadow shape with the input one to recover the correct position of the main light source. The final orientation of the environment map is directly related to the position of this main light source.We provide an evaluation of the proposed approach by calculating two metrics that compare our angle estimate with actual ground truth directions. Our orientation estimation shows that our method recovers a correct environment map orientation.In this thesis, we are interested in real input data. The environment map and the local scene are extracted from photographs or videos, which already contain a lighting rendering. It is therefore important to orient the environment map in a way that is consistent with the existing lighting in the local scene.We propose an automatic method, to orient an environment map to a local scene. This method is inspired by the behavior of light, drawing rays of light towards an object and attempting to match two shadows, one given as input and one calculated.We also use 3D data from the object we are considering. The originality is that we base our method on the way light behaves in order to calculate and match shadows. By matching the shadows, we can estimate the correct position of the environment map
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Paulovich, Fernando Vieira. "Mapeamento de dados multi-dimensionais - integrando mineração e visualização." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/55/55134/tde-04032009-145018/.
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As técnicas de projeção ou posicionamento de pontos no plano, que servem para mapear dados multi-dimensionais em espaços visuais, sempre despertaram grande interesse da comunidade de visualização e análise de dados por representarem uma forma útil de exploração baseada em relações de similaridade e correlação. Apesar disso, muitos problemas ainda são encontrados em tais técnicas, limitando suas aplicações. Em especial, as técnicas de projeção multi-dimensional de maior qualidade têm custo computacional proibitivo para grandes conjuntos de dados. Adicionalmente, problemas referentes à escalabilidade visual, isto é, à capacidade da metáfora visual empregada de representar dados de forma compacta e amigável, são recorrentes. Esta tese trata o problema da projeção multi-dimensional de vários pontos de vista, propondo técnicas que resolvem, até certo ponto, cada um dos problemas verificados. Também é fato que a complexidade e o tamanho dos conjuntos de dados indicam que a visualização deve trabalhar em conjunto com técnicas de mineração, tanto embutidas no processo de mapeamento, como por meio de ferramentas auxiliares de interpretação. Nesta tese incorporamos alguns aspectos de mineração integrados ao processo de visualização multi-dimensional, principalmente na aplicação de projeções para visualização de coleções de documentos, propondo uma estratégia de extração de tópicos. Como suporte ao desenvolvimento e teste dessas técnicas, foram criados diferentes sistemas de software. O principal inclui as técnicas desenvolvidas e muitas das técnicas clássicas de projeção, podendo ser usado para exploração de conjuntos de dados multi-dimensionais em geral, com funcionalidade adicional para mapeamento de coleções de documentos. Como principal contribuição desta tese propomos um entendimento mais profundo dos problemas encontrados nas técnicas de projeção vigentes e o desenvolvimento de técnicas de projeção (ou mapeamento) que são rápidas, tratam adequadamente a formação visual de grupos de dados altamente similares, separam satisfatoriamente esses grupos no layout, e permitem a exploração dos dados em vários níveis de detalheProjection or point placement techniques, useful for mapping multidimensional data into visual spaces, have always risen interest in the visualization and data analysis communities because they can support data exploration based on similarity or correlation relations. Regardless of that interest, various problems arise when dealing with such techniques, impairing their widespread application. In particularly the projections that yield highest quality layouts have prohibitive computational cost for large data sets. Additionally, there are issues regarding visual scalability, i.e., the capability of visually fit the individual points in the exploration space as the data set grows large. This thesis treats the problems of projections from various perspectives, presenting novel techniques that solve, to certain extent, several of the verified problems. It is also a fact that size and complexity of data sets suggest the integration of data mining capabilities into the visualization pipeline, both during the mapping process and as a tools to extract additional information after the data have been layed out. This thesis also add some aspects of mining to the multidimensional visualization process, mainly for the particular application of analysis of document collections, proposing and implementing an approach for topic extraction. As supporting tools for testing these techniques and comparing them to existing ones different software systems were written. The main one includes the techniques developed here as well as several of the classical projection and dimensional reduction techniques, and can be used for exploring various kinds of data sets, with addition functionality to support the mapping of document collections. This thesis contributes to the understanding of the projection or mapping problem and develops new techniques that are fast, treat adequately the visual formation of groups of highly related data items, separate those groups properly and allow exploration of data in various levels of detail
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Trigueiros, F. P. Maria-José. "Applications booléennes et projections polyèdrales." Grenoble INPG, 1994. http://www.theses.fr/1994INPG0060.
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Dans cette thèse, nous présentons une généralisation de l'approche polyédrale classique du problème de satisfiabilité d'un ensemble de fonctions booléennes {fl,…, fm} à n variables. Nous proposons d'élargir la représentation spatiale au graphe d'une application booléenne f = (fl,…, fm). Autrement dit, nous construisons le sous-ensemble des points de l'hypercube de dimension n+m dont les coordonnées sont les lignes de la table de vérité de fl,…, fm. Nous considérons ensuite l'enveloppe convexe de ces points. L'objet de ce travail est de donner un large ensemble d'applications booléennes dont le polytope associé admet par projection, une caractérisation polynomiale, c'est-à-dire une formulation compacte. La satisfiabilité des fonctions fl,…, fm pourra alors être déterminée en temps polynomial par des méthodes de programmation linéaire. La thèse est organisée comme suit: premièrement nous présentons le principe d'approche utilisée ici, que nous appelons projection par famille génératrice, et les résultats théoriques sur lesquels elle s'appuie. Deuxièmement, nous étudions trois classes d'applications booléennes. La première est bien connue, c'est celle des applications symétriques. Les deux autres qui la contiennent, sont nouvelles et sont les fonctions k-quasi―symétriques à n variables, 1≤k≤n, et leur concaténation. Finalement, nous appliquons la méthode de projection à ces applications pour obtenir des formulations compactes.
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Zhang, Jiaqi. "Minimizing Map Distortion Using Oblique Projections." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1512010345986894.
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Yildirim, Fatma Nur. "Représentations matricielles des fibres finies d’applications rationnelles et problèmes de distances." Thesis, Université Côte d'Azur, 2020. http://www.theses.fr/2020COAZ4004.
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Dans cette thèse, de nouvelles représentations matricielles des fibres finies d'applications rationnelles sont introduites et étudiées d'un point de vue théorique mais aussi pratique avec l'objectif de traiter des problèmes de distances, notamment les deux problèmes suivant : l'implicitisation des courbes rationnnelles algébriques en dimension arbitraire et la détermination des projetés orthogonaux d'un point sur une surface rationnelle algébrique en dimension trois. Les noyaux à gauche de ces représentations matrices, après évaluation en un point p de l'espace ambiant sont reliés aux pré-images du point p par l'application rationnelle considérée. De plus, ces matrices peuvent être pré-calculées et les pré-images d'un point p peuvent être calculées approximativement de manière efficace et robuste grâce aux outils d'algèbre linéaire. Dans le deuxième chapitre, une nouvelle famille des représentations matricielles est proposée pour les courbes algébriques rationnelles. Elle est basée sur le concept de "quadriques mobiles" associées aux courbes parametrées. Elle fournit une extension non linéaire des représentations matricielles qui sont obtenues au moyen du concept plus classique de "plans mobiles" associés à une paramétrisation. Ces matrices fournissent ainsi de nouvelles représentations implicites plus compactes pour les courbes rationnelles algébriques. Leurs entrées sont composées de formes linéaires et quadratiques en les variables de l'espace ambiant et leur rang chute exactement sur la courbe considérée. De plus, pour une courbe rationnelle générale de degré d ces nouvelles matrices sont deux fois plus petites en taille que les matrices, plus classiques, qui n'utilisent que des plans mobiles, et donc dont les entrées sont exclusivement composées de formes linéaires. Dans le troisième chapitre, le calcul des projetés orthogonaux d'un point sur une surface rationnelle algébrique dans l'espace projectif de dimension trois est étudié comme un problème d'inversion, plus précisément comme le calcul des fibre finies d'applications rationnelles génériquement finies et dominantes : les congruences des droites normales à une surface algébrique rationnelle. Une analyse fine des modules de relations (syzygies) associés à ces congruences est tout d'abord menée, puis utilisée pour construire des matrices eliminantes qui fournissent des représentations universelles de ces fibres finies. De plus, ces matrices dependent linéairement des variables de l'espace ambiant de dimension trois et elles peuvent être pré-calculées pour une surface algébrique rationnelle donnée. Enfin, l'appendice de cette thèse décrit les résultats obtenus lors d'un séjour de recherche mené chez le partenaire industriel Missler Software. Deux problèmes de distance en dimension trois ont été étudiés : le calcul de la distance entre un cercle et une droite puis le calcul de la distance entre un arc de cercle et un segment de droiteIn this thesis, implicit matrix-based representations of finite fibers of rational maps are studied theoretically and computationally for two problems: implicitization of rational algebraic curves in arbitrary dimension and orthogonal projections of a point onto an rational algebraic surface in three dimensional space. The proposed matrices have the property that their cokernels at a given point p in the target space of the rational map are in relation with the pre-images of the p via this rational map. In addition, these matrices can be pre-computed so that the pre-images of such a point p can be approximately computed by means of fast and robust numerical linear algebra tools. In the second chapter, a new family of implicit matrix representations is introduced for algebraic curves. It relies on the use of moving quadrics following curve parameterizations and provides a high-order extension of the implicit matrix representations built from their linear counterparts, the moving planes. Such matrices offer new, more compact, implicit representations of rational curves. Their entries are filled by linear and quadratic forms in the space variables and their ranks drop exactly on the curve. Typically, for a general rational curve of degree d we obtain a matrix whose size is half of the size of the corresponding matrix obtained with the moving planes method. In the third chapter, the problem of computing the orthogonal projections of a point onto a rational algebraic surface embedded in three dimensional projective space is turned into the problem of computing the finite fibers of a generically finite dominant rational map: a congruence of normal lines to the rational surface. Then, an in-depth study of certain syzygy modules associated to such a congruence is presented and applied to build elimination matrices that provide universal representations of its finite fibers, under some genericity assumptions. Moreover, these matrices depend linearly in the variables of the three dimensional space and can be pre-computed for a given rational surface. Lastly, the appendix of this thesis reports on a three-month industrial secondment at the company Missler Software where two distance problems are treated : distance between a circle and a line in 3D and distance between an arc of a circle and a segment of a line in three dimensional space
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Taylor, John-Paul. "Ipsilateral corticospinal projections in man." Thesis, University of Newcastle Upon Tyne, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341447.
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Draper, Christopher Peter William. "The geodesic Gauss map of spheres and complex projective space." Thesis, University of York, 2015. http://etheses.whiterose.ac.uk/11542/.
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For an isometrically immersed submanifold, the spherical Gauss map is the induced immersion of the unit normal bundle into the unit tangent bundle. Compact rank one symmetric spaces have the distinguishing feature that their geodesics are closed with the same period, and so we can define the manifold of geodesics as the quotient of the unit tangent bundle by geodesic flow. Through this quotient we define the geodesic Gauss map to be the Lagrangian immersion given by the projection of the spherical Gauss map. In this thesis we establish relationships between the minimality of isometrically immersed submanifolds of the sphere and complex projective space and the minimality of the geodesic Gauss map with respect to the Kähler-Einstein metric on the manifold of geodesics. In particular, we establish that for an isometrically immersed holomorphic submanifold of complex projective space, its geodesic Gauss map is minimal Lagrangian if it has conformal shape form.
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Conway, Elizabeth Ann. "The development of corticospinal projections in man." Thesis, University of Newcastle Upon Tyne, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296148.
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Hennerdal, Pontus. "Education through Maps : The Challenges of Knowing and Understanding the World." Doctoral thesis, Stockholms universitet, Kulturgeografiska institutionen, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-119809.
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The overall purpose of this thesis is to study, in relation to geography education and with a historical perspective, the challenges of knowing and understanding the world. The cases are all from Sweden. In the first paper, educational ideas in the nineteenth and early twentieth centuries are studied, and the results indicate that some of the previously criticised educational ideas that were perceived as resulting from the ideas of nineteenth century regional geography in fact can be observed in earlier centuries and were criticised during the nineteenth century. In the second paper, school children’s ability to locate geographical names on outline maps is compared with children’s ability to complete the same task 45 years earlier. A total of 1,124 students were included in the latter study, and the results were compared with those from a study of 1,200 students from the same town conducted in 1968. The results raise questions regarding the picture of the continuous decline in children’s school results and show, for example, that children today are better at locating continents on a world map. The final paper identifies a new aspect of map reading difficulties. These difficulties in map reading are increasingly important in our global society, i.e., how the edges of the world map cohere. The paper shows that many map readers, children and adults, respond according to the idea of linear peripheral continuity, which indicates that the proposed continuation is along the straight line that continues tangentially to the original route when it crosses the edge. In general, this understanding leads to incorrect interpretations of the continuation of world maps.At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 2: Accepted.
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Stagliano', Giovanni. "On special quadratic birational transformations of a projective space." Doctoral thesis, Università di Catania, 2013. http://hdl.handle.net/10761/1337.
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A birational map from a projective space onto a not too much singular projective variety with a single irreducible non-singular base locus scheme (special birational transformation) is a rare enough phenomenon to allow meaningful and concise classification results.
We shall concentrate on transformations defined by quadratic equations onto some varieties (especially projective hypersurfaces of small degree), where quite surprisingly the base loci are interesting projective manifolds appearing in other contexts; for example, exceptions for adjunction theory, small degree or small codimensional manifolds, Severi or more generally homogeneous varieties.
In particular, we shall classify:
quadro-quadric transformations into a quadric hypersurface;
quadro-cubic transformations into a del Pezzo variety;
transformations whose base locus (scheme) has dimension at most three.
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Doman, David Burke. "Projection Methods for Order Reduction of Optimal Human Operator Models." Diss., Virginia Tech, 1998. http://hdl.handle.net/10919/30637.
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Human operator models developed using optimal control theory
are typically complicated and over-parameterized, even for
simple controlled elements. Methods for generating less
complicated operator models that preserve the most important
characteristics of the full order model are developed so
that the essential features of the operator dynamics are
easier to determine. A new formulation of the Optimal
Control Model (OCM) of the human operator is developed
that allows order reduction techniques to be applied in
a meaningful way. This formulation preserves the critical
neuromotor dynamics and time delay characteristics of the
human operator. The Optimal Projection (OP) synthesis
technique is applied to a modified version of the OCM.
Using OP synthesis allows one to determine operator models
that minimize the quadratic performance index of the OCM
with a constraint on model order. This technique allows
analysts to formulate operator models of fixed order.
Operator model reduction methods based on variations of
balanced realization techniques are also developed since
they reduce the computational complexity associated with
OP synthesis yet maintain a reasonable level of accuracy.
Computer algorithms are developed that insure that the
reduced order models have noise to signal ratios that are
consistent with OCM theory. The OP method generates
operator models of fixed order that are consistent with
OCM theory in all respects, i.e. optimality, neuromotor
lag, time delay, and noise to signal ratios are all
preserved. The other model reduction techniques preserve
these features with the exception of optimality. Each
technique is applied to a variety of controlled elements
to illustrate how performance and frequency response
fidelity degrade when the order of the operator model is
reduced.Ph. D.
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Layden, Tracy. "Factoring the Duplication Map on Elliptic Curves for use in Rank Computations." Scholarship @ Claremont, 2013. http://scholarship.claremont.edu/scripps_theses/342.
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This thesis examines the rank of elliptic curves. We first examine the correspondences between projective space and affine space, and use the projective point at infinity to establish the group law on elliptic curves. We prove a section of Mordell’s Theorem to establish that the abelian group of rational points on an elliptic curve is finitely generated. We then use homomorphisms established in our proof to find a formula for the rank, and then provide examples of computations.
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Wilson, Gina Nicole. "PRE-DEGENERATIVE CHANGES IN THE RETINOFUGAL PROJECTION OF DBA/2J GLAUCOMATOUS MICE." Kent State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=kent1501466545809801.
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Raguin, Odile. "Pour un Test projectif tactile à partir des planches de Rorschach en relief : de la Perception tactile à la Représentation." Thesis, Lyon 2, 2015. http://www.theses.fr/2015LYO20057/document.
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La plupart des méthodes projectives (Didier ANZIEU, Catherine CHABERT, 1961) ont comme support de travail la vue. Le processus haptique est-il suffisamment discriminatif pour valider la fiabilité de ce test sous ce mode ? Un étalonnage différencié respecte-t-il la valeur donnée à ce test par H. Rorschach ? Le sujet, en perdant la vue, va devoir mobiliser ou trouver des nouvelles ressources physiques et psychiques pour devenir autonome et poursuivre sa vie. Tout en lui est effracté : sa construction narcissique, sa représentation du monde et son altérité dans le regard de l’autre. Le Rorschach permet d’aborder la richesse psychique d’un sujet. Il nous donne à voir les potentialités psychiques du sujet dans sa relation à lui-même et aux autres. Or, il fait appel à une activité visuelle qui organise un matériel informel. C’est une activité imageante qui fait passer du perceptif au projectif, du perçu au vécu…Le toucher, dans certaines situations, peut être un relais de perception, de projection et donner à voir les représentations du sujet. Cette recherche peut permettre d’envisager une autre manière d’étalonner ce test afin de pouvoir le quantifier, le qualifier en changeant par exemple l’item « couleur » par l’item texture…Dans cette étude, il nous faut vérifier que cela n’enlève pas la valeur que donnait H. Rorschach à ce test, à cet item mais au contraire l’ouvre à une autre dimension clinique, celle d’une clinique spécifique du sujet mal ou non-voyant. En respectant un protocole spécifique, une telle passation permettrait une médiation pour le sujet en situation de handicap visuel vers une « meilleure » ré-élaboration de son projet de vie. Par ailleurs, cette étude pourrait ouvrir d’autres approches sur le dessin en relief et permettre notamment à toute une partie de la population vieillissante d’utiliser cette modalité dans la vie quotidienne, pour de nouveaux repèresThis research follows a study already begun in Master 1; it deals with the haptic process adapted to 3-dimensional Rorschach-plates. Is the haptic process sufficiently discriminating to validate the reliability of this test under this mode ? Does differentiated calibration respect the values given to this test by H. Rorschach ? After loss of sight, a subject is going to have to mobilize or find new physical and psychic resources to become autonomous and go on living. Everything in that person is broken: their narcissistic construction, their representation of the world and their differences in the eye of others. The Rorschach test allows us to approach a subject’s psychic wealth. It shows us the psychic potential of a subject in relation to himself and to others. Yet the Rorschach test calls on visual activity to organize an informal material. It is an activity based on images which leads one from the perceptive to the projective, from perceived to experienced. In certain situations, touch can be an intermediary for perception, for projection and can show how the subject is represented. Through this research, we can consider calibrating this test in another way in order to measure quantity and quality by changing “colour” for ‘texture’, for example. In this study, it is essential to verify that this does not remove the value given by H. Rorschach to this item in this test, but on the contrary opens it to other clinical dimensions, that specific of the blind or partially-sighted.Moreover, this study could open up new approaches to 3-dimensional drawings and allow a great part of the ageing population to use this method in daily life, to find new bearings. For instance, using certain textures to find one’s way around the flat by 3-dimensional pictograms
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Baroya, Sydney. "Real-time Body Tracking and Projection Mapping in the Interactive Arts." DigitalCommons@CalPoly, 2020. https://digitalcommons.calpoly.edu/theses/2250.
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Projection mapping, a subtopic of augmented reality, displays computer-generated light visualizations from projectors onto the real environment. A challenge for projection mapping in performing interactive arts is dynamic body movements. Accuracy and speed are key components for an immersive application of body projection mapping and dependent on scanning and processing time.
This thesis presents a novel technique to achieve real-time body projection mapping utilizing a state of the art body tracking device, Microsoft’s Azure Kinect DK, by using an array of trackers for error minimization and movement prediction. The device's Sensor and Bodytracking SDKs allow multiple device synchronization. We combine our tracking results from this feature with motion prediction to provide an accurate approximation for body joint tracking. Using the new joint approximations and the depth information from the Kinect, we create a silhouette and map textures and animations to it before projecting it back onto the user. Our implementation of gesture detection provides interaction between the user and the projected images.
Our results decreased the lag time created from the devices, code, and projector to create a realistic real-time body projection mapping. Our end goal was to display it in an art show. This thesis was presented at Burning Man 2019 and Delfines de San Carlos 2020 as interactive art installations.
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Barr, Michael. "The Influence of the Projected Coordinate System on Animal Home Range Estimation Area." Scholar Commons, 2014. https://scholarcommons.usf.edu/etd/5343.
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Animal home range estimations are important for conservation planning and protecting the habitat of threatened species. The accuracy of home range calculations is influenced by the map projection chosen in a geographic information system (GIS) for data analysis. Different methods of projection will distort spatial data in different ways, so it is important to choose a projection that meets the needs of the research. The large number of projections in use today and the lack of distortion comparison between the various types make selecting the most appropriate projection a difficult decision. The purpose of this study is to quantify and compare the amount of area distortion in animal home range estimations when projected into a number of projected coordinate systems in order to understand how the chosen projection influences analysis. The objectives of this research are accomplished by analyzing the tracking data of four species from different regions in North and South America. The home range of each individual from the four species datasets is calculated using the Characteristic Hull Polygon method for home range estimation and then projected into eight projected coordinate systems of various scales and projection type, including equal area, conformal, equidistant, and compromise projections. A continental Albers Equal Area projection is then used as a baseline area for the calculation of a distortion measurement ratio and magnitude of distortion statistic. The distortion measurement ratio and magnitude calculations provide a measurement of the quantity of area distortion caused by a projection. Results show the amount distortion associated with each type of projection method and how the amount of distortion changes for a projection based on geographic location. These findings show how the choice of map projection can have a large influence on data analysis and illustrate the importance of using an appropriate PCS for the needs of a given study. Distorted perceptions can influence decision-making, so it is important to recognize how a map projection can influence the analysis and interpretation of spatial data.
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Bahy-El-Dien, A. A. "On the construction of harmonic two-spheres in complex hyperquadrics and quaternionic projective spaces." Thesis, University of Leeds, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384090.
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Yek, Vorleak. "Numerical Investigation on the Projection Method for the Incompressible Navier-Stokes Equations on MAC Grid." Thesis, California State University, Long Beach, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10825591.
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The motion of a viscous fluid flow is described by the well-known Navier-Stokes equations. The Navier-Stokes equations contain the conservation laws of mass and momentum, and describe the spatial-temporal change of the fluid velocity field. This thesis aims to investigate numerical solvers for the incompressible Navier-Stokes equations in two and three space dimensions. In particular, we focus on the second-order projection method introduced by Kim and Moin, which was extended from Chorin’s first-order projection method. We apply Fourier-Spectral methods for the periodic boundary condition. Numerically, we discretize the system using central differences scheme on Marker and Cell (MAC) grid spatially and the Crank-Nicolson scheme temporally. We then apply the fast Fourier transform to solve the resulting Poisson equations as sub-steps in the projection method. We will verify numerical accuracy and provide the stability analysis using von Neumann. In addition, we will simulate the particles' motion in the 2D and 3D fluid flow.
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Oukili, Ahmed. "Reconstruction statistique 3D à partir d’un faible nombre de projections : application : coronarographie RX rotationnelle." Thesis, Rennes 1, 2015. http://www.theses.fr/2015REN1S109/document.
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La problématique de cette thèse concerne la reconstruction statistique itérative 3D de l'arbre coronaire, à partir d'un nombre très réduit d'angiogrammes coronariens (5 images). Pendant un examen rotationnel d'angiographie RX, seules les projections correspondant à la même phase cardiaque sont sélectionnées afin de vérifier la condition de non variabilité spatio-temporelle de l'objet à reconstruire (reconstruction statique). Le nombre restreint de projections complique cette reconstruction, considérée alors comme un problème inverse mal posé. La résolution d'un tel problème nécessite une procédure de régularisation. Pour ce faire, nous avons opté pour le formalisme bayésien en considérant la reconstruction comme le champ aléatoire maximisant la probabilité a posteriori (MAP), composée d'un terme quadratique de vraisemblance (attache aux données) et un a priori de Gibbs (à priori markovien basé sur une interprétation partielle de l'objet à reconstruire). La maximisation MAP adoptant un algorithme d'optimisation numérique nous a permis d'introduire une contrainte de lissage avec préservation de contours des reconstructions en choisissant adéquatement les fonctions de potentiel associées à l'énergie à priori. Dans ce manuscrit, nous avons discuté en détail des trois principales composantes d'une reconstruction statistique MAP performante, à savoir (1) l'élaboration d'un modèle physique précis du processus d'acquisition, (2) l'adoption d'un modèle à priori approprié et (3) la définition d'un algorithme d'optimisation itératif efficace. Cette discussion nous a conduit à proposer deux algorithmes itératifs MAP, MAP-MNR et MAP-ARTUR-GC, que nous avons testés et évalués sur des données simulées réalistes (données patient issues d'une acquisition CT- 64 multi-barrettes)The problematic of this thesis concerns the statistical iterative 3D reconstruction of coronary tree from a very few number of coronary angiograms (5 images). During RX rotational angiographic exam, only projections corresponding to the same cardiac phase are selected in order to check the condition of space and time non-variability of the object to reconstruct (static reconstruction). The limited number of projections complicates the reconstruction, considered then as an illness inverse problem. The answer to a similar problem needs a regularization process. To do so, we choose baysian formalism considering the reconstruction as a random field maximizing the posterior probability (MAP), composed by quadratic likelihood terms (attached to data) and Gibbs prior (prior markovian based on a partial interpretation of the object to reconstruct). The MAP maximizing allowed us using a numerical optimization algorithm, to introduce a smoothing constraint and preserve the edges on the reconstruction while choosing wisely the potential functions associated to prior energy. In this paper, we have discussed in details the three components of efficient statistical reconstruction MAP, which are : 1- the construction of precise physical model of acquisition process; 2- the selection of an appropriate prior model; and 3- the definition of an efficient iterative optimization algorithm. This discussion lead us to propose two iterative algorithms MAP, MAP-MNR and MAP-ARTUR-GC, which we have tested and evaluated on realistic simulated data (Patient data from 64-slice CT)
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Josi, Johannes. "Nodal rational sextics in the real projective plane." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS076.
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Cette thèse est consacrée à l’étude des courbes sextiques nodales, et en particulier des sextiques rationnelles, dans le plan projectif réel. Deux sextiques nodales réelles ayant k points doubles sont dites rigidement isotopes si elles peuvent être reliées par un chemin dans l’espace des sextiques nodales réelles ayant k points doubles. Le résultat principal de la première partie de la thèse donne une classification à isotopie rigide près des sextiques nodales irréductibles sans points doubles réels, généralisant la classification des sextiques non-singulières obtenue par Nikulin. La seconde partie porte sur les sextiques ayant des points doubles réels : une classification est obtenue pour les sextiques nodales séparantes, c’est-à-dire celles dont la partie réelle sépare leur complexification (l’ensemble des points complexes) en deux composantes connexes. Ce résultat est appliqué au cas des sextiques rationnelles réelles pouvant être perturbées en des sextiques maximales ou presque maximales (dans le sens de l’inégalité de Harnack). L’approche retenue repose sur l’étude des périodes des surfaces K3, se basant notamment sur le Théorème de Torelli Global de Piatetski-Shapiro et Shafarevich et le Théorème de Surjectivité de Kulikov, ainsi que sur les résultats de Nikulin portant sur les formes bilinéaires symétriques intégralesThis thesis studies nodal sextics (algebraic curves of degree six), and in particular rational sextics, in the real projective plane. Two such sextics with k nodes are called rigidly isotopic if they can be joined by a path in the space of real nodal sextics with k nodes. The main result of the first part of the thesis is a rigid isotopy classification of real nodal sextics without real nodes, generalizing Nikulin’s classification of non-singular sextics. In the second part we study sextics with real nodes and we describe the rigid isotopy classes of such sextics in the case where the sextics are dividing, i.e., their real part separates the complexification (the set of complex points) into two halves. As a main application, we give a rigid isotopy classification for those nodal real rational sextics which can be perturbed to maximal or next-to-maximal sextics in the sense of Harnack’s inequality. Our approach is based on the study of periods of K3 surfaces, drawing on the Global Torelli Theorem by Piatetski-Shapiro and Shafarevich and Kulikov’s surjectivity theorem, as well as Nikulin’s results on symmetric integral bilinear forms
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Torres, Maria da Madre de Deus Vilas Boas Pinheiro. "Design empático no projecto de um mapa turístico temático de Lisboa." Master's thesis, Universidade de Lisboa, Faculdade de Arquitetura, 2015. http://hdl.handle.net/10400.5/13646.
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Silva, Manuel José Alves Ventura da. "Co-projecto em FPGA da MAC IEEE 802.11p para comunicações veiculares." Master's thesis, Universidade de Aveiro, 2011. http://hdl.handle.net/10773/7311.
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Mestrado em Engenharia Electrónica e TelecomunicaçõesThe advancements and dissemination of telecommunication technologies has caused them to be employed more and more in our day-to-day life. Recently, these technologies have been applied to vehicles, as a way of not only improving driving safety but also the drivers' and passengers' comfort. If vehicular communications are to become a reality, communication standards must be created in order to allow the development of compatible communication platforms, while also serving as a basys for application development. The standards IEEE WAVE, alongside the IEEE 802.11p amendment, were proposed in order to meet these demands and address some of the speci c issues with vehicular networks, such as short connectivity times and the highly dynamic nature of the propagation environment. This thesis ts within the HEADWAY project, the goal of which is the creation of a device that will perform communication between vehicles. In order to incorporate every layer of the WAVE (Wireless Access in Vehicular Environments) protocol stack, a development platform was conceived that will enable the creation of a standardized communications system for vehicles. The development platform created features an antenna, RF modules, DAC and ADC circuits, an FPGA, a general purpose microprocessor and a GPS module. This work is focused in the development and implementation in FPGA of a MAC layer in accordance with the WAVE standards. The MAC layer's di erent functionalities were divided according to their complexity and execution time, causing our MAC's division in Upper MAC (UMAC) and Lower MAC (LMAC). The UMAC will be implemented in software (C) running in an FPGA embedded microprocessor and will contain the MAC's functions that are more complex, algorithmically speaking, but are not required to be excuted in a very short time interval, such as frame processing and decoding. The LMAC will be implemented by VHDL modeled hardware logic and will perform time critical functions, such as the timestamping of received frames, and complex calculations that bene t from the paralelism o ered by hardware logic, such as CRC computation and error checking. This MAC layer was implemented in an FPGA and its mechanisms were validated.
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Liu, Sam Chi-Hao. "An investigation of potential interactions between Ten-m3 and EphA7 in the formation of binocular visual circuits." Thesis, The University of Sydney, 2021. https://hdl.handle.net/2123/27416.
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Because the precise alignment between contralateral and ipsilateral visual circuits is important for the development of visual system, both circuits need to be precisely regulated concurrently. Eph-ephrin and Teneurin are two protein families that may have important roles in regulating the development of the visual pathway (Kania & Klein, 2016; Leamey & Sawatari, 2014). However, while the roles of Eph-ephrin in the development of contralateral projection have been widely studied (Kania & Klein, 2016), the numbers of studies that have focused on ipsilateral projection is relatively low. On the other hand, while the roles of teneurins in ipsilateral projection have been reported, their roles in the formation of contralateral projections are less well-known. Glendining et al (2017) recently showed that there is a potential interaction between Ten-m3 and EphA7 as the expression of EphA7 was reduced in Teneurin transmembrane protein 3 (Ten-m3) KO (Glendining et al., 2017). This thesis will investigate the roles of Ten-m3 and EphA7 in regulating the development of ipsilateral and contralateral projections during the formation of topographic map in visual system respectively. The results point to complementary roles for Ten-m3 and EphA7 in regulating the development of ipsilateral projections in the visual system. However, similar topographic errors were found in the patterning of contralateral projections in the visual system in Ten-m3 KO and EphA7 KO. This suggest that Ten-m3 and EphA7 may have different roles during the development of ipsilateral and contralateral projections. Behavioural studies revealed a potential deficit in the ability of EphA7 KO mice to discriminate between visual stimuli located in their dorsal visual field, suggesting the functional importance of EphA7 in visual behaviors.
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Sbeih, Reema. "NON-LINEAR MAPS BETWEEN SUBSETS OF BANACH SPACES." Kent State University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=kent1251217291.
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Wang, Juanyong. "Positivity of direct images and projective varieties with nonnegative curvature." Thesis, Institut polytechnique de Paris, 2020. http://www.theses.fr/2020IPPAX048.
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La classification birationnelle des variétés algébrique est un problématique central en géométrie algébrique. Récemment grand progrès a été fait vers l'établissement du MMP et l'abondance, et par ces travaux, les variété projectives lisse (ou légèrement singulières) sont birationnellement divisées en deux catégories: 1. les variétés à diviseur canonique pseudo-effectif, qui sont montré d'aboutir à un modèle minimal par le MMP; 2. les variétés uniréglées, qui sont recouvertes par des courbes rationnelles. Dans cette thèse, des étude raffinées de ces deux catégories de variétés est sont effectuées respectivement, by en suivant la philosophie d'étudier les fibrations canoniques y associées.Pour une variété X dans la première catégorie, la fibration la plus importante y associée est la fibration d'Iitaka-Kodaira, dont la base est de dimension égale à la dimension de Kodaira de X. Cette thèse traite un corollaire important de l'abondance, à savoir, la conjecture C_{n,m} d'Iitaka, qui énonce la sup-additivité de la dimension de Kodaira dimension par rapport aux fibration algébrique. Dans cette thèse la version kählérienne de C_{n,m} est montré sous l'hypothèse que la base est un tore complexe en développant davantage la positivité des images directes et la version pluricanonique du théorème à la Green-Lazarsfeld-Simpson sur les lieux de sauts de cohomologie. Ceci généralise le résultat principal de Cao-Păun (2017). Pour les variétés dans la seconde catégorie, l'on étude l'application d'Albanese et la fibration MRC fibration, au lieu de la fibration d'Iitaka-Kodaira. La philosophie dans cette enquête est que si le fibré tangent ou anticanonique admet une certaine positivité, les deux fibrations susmentionnées doivent avoir une structure rigide. Dans cette thèse j'étudie la structure des variétés projective (légèrement singulières) à diviseur anticanonique nef. En appliquant la positivité des images directe et des résultats de la théorie des feuilletages, j'arrive à démontrer que l'application d'Albanese map est une fibration localement constante et que si le lieu lisse est simplement connexe la fibration MRC induit une décomposition en un produit. Ceci généralise les résultats correspondants pour les variétés lisses dans Cao (2019) and Cao-Höring (2019)The birational classification of algebraic varieties is a central problem in algebraic geometry. Recently great progress has been made towards the establishment of the MMP and the Abundance and by these works, smooth (or mildly singular) projective varieties can be birationally divided into two categories: 1. varieties with pseudoeffective canonical divisor, which are shown to reach a minimal model under the MMP; 2. uniruled varieties, which are covered by rational curves. In this thesis refined studies of these two categories of varieties are carried out respectively, by following the philosophy of studying the canonical fibrations associated to them.For any variety X in the first category, the most important canonical fibration associated to X is the Iitaka-Kodaira fibration whose base variety is of dimension equal to the Kodaira dimension of X. This thesis tacles an important corollary of the Abundance conjecture, namely, the Iitaka conjecture C_{n,m}, which states the supadditivity of the Kodaira dimension with respect to algebraic fibre spaces. In this thesis the Kähler version of C_{n,m} is proved under the assumption that the base variety of the fibre space is a complex torus by further developping the positivity theorem of direct images and the pluricanonical version of the Green-Lazarsfeld-Simpson type theorem on cohomology jumping loci. This generalizes the main result of Cao-Păun (2017).As for varieties in the second category, one studies the Albanese map and the MRC fibration, instead of the Iitaka-Kodaira fibration. A philosophy in this investigation is that when the tangent bundle or the anticanonical divisor admits certain positivity, the aforementioned two fibrations of the variety should have a rigid structure. In this thesis I study in this thesis the structure of (mildly singular) projective varieties with nef anticanonical divisor. By again applying the positivity of direct images and by applying results from the foliation theory, I manage to prove that the Albanese map of such variety is a locally constant fibration and that if its smooth locus is simply connected then the MRC fibration induces a splitting into a product. These generalize the corresponding results for smooth projective varieties in Cao (2019) and Cao-Höring (2019)
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Horák, Michael. "Určení polohy stanic v síti Internet pomocí přenosového zpoždění." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2013. http://www.nusl.cz/ntk/nusl-220305.
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This thesis covers the topic of determination of geographical location of a host in internet network while utilizing measurement of the end to end delay and implementation of Constraint-Based Geolocation. Gradually I go through issue of the delay in computer networks and ways how to measure it. Next chapter describes a few ways to geolocate host in internet network with emphasis on the CBG method. Another chapter is dedicated to describing a way to project spherical coordinates to the two dimensional space, which has been used in implementation of geolocation method. Chapter about implementation builds upon the facts given in previous chapters while functions of the program written in the JAVA programing language are being explained. Two similar geolocation methods were implemented. By comparing the results gained by implementation, new method of geolocation is proposed and devised. It combines properities of both previous methods. There are results of the implemented methods and their comparation to the one of the source documents used in creation of this thesis in summary section.
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Godfrey, Keith B. "From synaptogenesis to map formation - modeling visual system development exploring the contribution of cellular mechanisms to the emergence of retinotopic projections and eye-specific segregation." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/5754.
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The brain is composed of many anatomically distinct areas that control different functions. A
common feature of these areas is that information is represented in a spatially organized manner. In
the visual system, retinal representation is spatially mapped onto visual areas such that neighboring
neurons respond to adjacent retinal locations, forming a retinotopic map. When axons from two
retinas project to the same target structure, both produce similar retinotopic projections on the
large scale but these segregate into eye-specific domains locally. How these spatial representations
are formed is not well understood. Experimental studies have shown that many mechanisms are
involved.
Several modeling studies have addressed how such organization arises, with most representing
different varying subsets of the mechanisms known to be present and showing how the particular
representation of mechanisms can produce the emergent properties of organization. This results
in models producing similar outputs yet coming to different conclusions that often cannot be reconciled.
By omitting behaviors that are present and likely to be involved in organization, such
as spiking neurons and the dynamics of axon and synapse growth and retraction, the models are
poorly constrained. This limits their explanatory and predictive scope regarding how organization
develops, and further limits their ability to examine how the different mechanisms interact.
To more accurately analyze both how such organization develops and the interactions between
underlying mechanisms, a model of the developing retinocollicular pathway was produced that
represented a wide range of cellular and subcellular phenomena, including spike-timing dependent
plasticity (STDP), chemoaffinity, spontaneous retinal activity, trophic factors, and growth and
retraction of synapses and axons. The model demonstrated retinotopic refinement and eye-specific
segregation across a wide range of parameters and variations in implementation. Results indicated
that the mechanisms necessary for organization were chemoaffinity, retinal waves, trophic factors
and homeostatic controls. Analysis of the relative roles of activity and chemoaffinity suggested that
these mechanisms play distinct and complementary roles. Among the predictions of the model are
that smaller synapses produce more refined projections and, surprisingly, that STDP does not play
a significant role in organization.
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Cheaytou, Rima. "Etude des méthodes de pénalité-projection vectorielle pour les équations de Navier-Stokes avec conditions aux limites ouvertes." Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4715.
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L'objectif de cette thèse consiste à étudier la méthode de pénalité-projection vectorielle notée VPP (Vector Penalty-Projection method), qui est une méthode à pas fractionnaire pour la résolution des équations de Navier-Stokes incompressible avec conditions aux limites ouvertes. Nous présentons une revue bibliographique des méthodes de projection traitant le couplage de vitesse et de pression. Nous nous intéressons dans un premier temps aux conditions de Dirichlet sur toute la frontière. Les tests numériques montrent une convergence d'ordre deux en temps pour la vitesse et la pression et prouvent que la méthode est rapide et peu coûteuse en terme de nombre d'itérations par pas de temps. En outre, nous établissons des estimations d'erreurs de la vitesse et de la pression et les essais numériques révèlent une parfaite concordance avec les résultats théoriques. En revanche, la contrainte d'incompressibilité n'est pas exactement nulle et converge avec un ordre de O(varepsilondelta t) où varepsilon est un paramètre de pénalité choisi assez petit et delta t le pas temps. Dans un second temps, la thèse traite les conditions aux limites ouvertes naturelles. Trois types de conditions de sortie sont étudiés et testés numériquement pour l'étape de projection. Nous effectuons des comparaisons quantitatives des résultats avec d'autres méthodes de projection. Les essais numériques sont en concordance avec les estimations théoriques également établies. Le dernier chapitre est consacré à l'étude numérique du schéma VPP en présence d'une condition aux limites ouvertes non-linéaire sur une frontière artificielle modélisant une charge singulière pour le problème de Navier-StokesMotivated by solving the incompressible Navier-Stokes equations with open boundary conditions, this thesis studies the Vector Penalty-Projection method denoted VPP, which is a splitting method in time. We first present a literature review of the projection methods addressing the issue of the velocity-pressure coupling in the incompressible Navier-Stokes system. First, we focus on the case of Dirichlet conditions on the entire boundary. The numerical tests show a second-order convergence in time for both the velocity and the pressure. They also show that the VPP method is fast and cheap in terms of number of iterations at each time step. In addition, we established for the Stokes problem optimal error estimates for the velocity and pressure and the numerical experiments are in perfect agreement with the theoretical results. However, the incompressibility constraint is not exactly equal to zero and it scales as O(varepsilondelta t) where $varepsilon$ is a penalty parameter chosen small enough and delta t is the time step. Moreover, we deal with the natural outflow boundary condition. Three types of outflow boundary conditions are presented and numerically tested for the projection step. We perform quantitative comparisons of the results with those obtained by other methods in the literature. Besides, a theoretical study of the VPP method with outflow boundary conditions is stated and the numerical tests prove to be in good agreement with the theoretical results. In the last chapter, we focus on the numerical study of the VPP scheme with a nonlinear open artificial boundary condition modelling a singular load for the unsteady incompressible Navier-Stokes problem
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Roquefeuil, Alexis. "Confluence of quantum K-theory to quantum cohomology for projective spaces." Thesis, Angers, 2019. http://www.theses.fr/2019ANGE0019/document.
Full textAbstract:
En géométrie algébrique, les invariants de Gromov—Witten sont des invariants énumératifs qui comptent le nombre de courbes complexes dans une variété projective lisse qui vérifient des conditions d’incidence. En 2001, A. Givental et Y.P. Lee ont défini de nouveaux invariants, dits de Gromov—Witten K-théoriques, en remplaçant les définitions cohomologiques dans la construction des invariants de Gromov—Witten par leurs analogues K-théoriques. Une question essentielle est de comprendre comment sont reliées ces deux théories. En 2013, Iritani- Givental-Milanov-Tonita démontrent que les invariants K-théoriques peuvent être encodés dans une fonction qui vérifie des équations aux q-différences. En général, ces équations fonctionnelles vérifient une propriété appelée “confluence”, selon laquelle on peut dégénérer ces équations pour obtenir une équationdifférentielle. Dans cette thèse, on propose de comparer les deux théories de Gromov— Witten à l’aide de la confluence des équations aux q-différences. On montre que, dans le cas des espaces projectifs complexes, que ce principe s’adapte et que les invariants Kthéoriques peuvent être dégénérés pour obtenir leurs analogues cohomologiques. Plus précisément, on montre que la confluence de la petite fonction J de Givental K-théorique permet de retrouver son analogue cohomologique après une transformation par le caractère de ChernIn algebraic geometry, Gromov— Witten invariants are enumerative invariants that count the number of complex curves in a smooth projective variety satisfying some incidence conditions. In 2001, A. Givental and Y.P. Lee defined new invariants, called Ktheoretical Gromov—Witten invariants. These invariants are obtained by replacing cohomological objects used in the definition of the usual Gromov—Witten invariants by their Ktheoretical analogues. Then, an essential question is to understand how these two theories are related. In 2013, Iritani-Givental- Milanov-Tonita show that K-theoretical Gromov—Witten invariants can be embedded in a function which satisfies a q-difference equation. In general, these functional equations verify a property called “confluence”, which guarantees that we can degenerate these equations to obtain a differential equation. In this thesis, we propose to compare our two Gromov—Witten theories through the confluence of q-difference equations. We show that, in the case of complex projective spaces, this property can be adapted to degenerate Ktheoretical invariants into their cohomological analogues. More precisely, we show that theconfluence of Givental’s small K-theoretical Jfunction produces its cohomological analogue after applying the Chern character
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Kong, Maynard. "Characteristic classes of modules." Pontificia Universidad Católica del Perú, 2014. http://repositorio.pucp.edu.pe/index/handle/123456789/97347.
Full textAbstract:
In this paper we have developed a general theory of characteristic classes of modules. To a given invariant map defined on a Lie algebra, we associate a cohomology class by using the curvature form of a certain kind of connections. Here we present a very simple proof of the invariance theorem (Theorem 12), which states that equivalent connections give rise to the same characteristic class. We have used those invariant maps of {9} to define Chern classes of projective modules and we have derived their basic properties. It might be interesting to observe that this theory could be applied to define characteristic classes of bilinear maps. In particular, the Euler classes of {6} can be obtained in this way.
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Sichacá, Martín Barajas. "Sobre a geometria diferencial do cross-cap no 3-espaço Euclidiano." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/55/55135/tde-10042017-103122/.
Full textAbstract:
Nesta tese estudamos a geometria diferencial do cross-cap usando ferramentas da teoria de singularidades. Estudamos curvas definidas sobre uma superfície regular que captam o contato da superfície com planos e esferas e estendemos o estudo para o cross-cap. Consideramos os fenômenos locais que ocorrem genericamente na família de projeções ortogonais do cross-cap e obtemos informações detalhadas sobre as bifurcações da projeção do conjuntos dos pontos duplos juntamente com a do contorno aparente. Estudamos as simetrias reflexõais infinitesimais do cross-cap através das singularidades da família da aplicações dobra e damos uma caracterização geométrica das mesmas. Finalmente, consideramos dualidade nas equações diferenciais binárias que definem as curvas assintóticas e as linhas de curvatura sobre o cross-cap. Estudamos o conjunto dos pontos onde ocorrem as inflexões de tais curvas e a relação deste conjunto com o conjunto sub-parabólico e flecnodal.In this thesis we study the differential geometry of the cross-cap using singularity theory. We study curves on a regular surface that capture the contact of the surface with planes and spheres and extend our study to the cross-cap. We deal with local phenomena that occur generically in the family of orthogonal projection of the cross-cap and obtain detailed information about the bifurcations of the projection of double point curve together with the profile. We study the infinitesimal reflectional symmetry of a cross-cap via the singularities of the fold maps and give a geometrical characterization of these maps. Finally, we consider the duality in the binary differential equations of the asymptotic curves and of the curvature lines on a cross-cap. We study the inflection set of this curves and their relation with the subparabolic set and the flecnodal curve.
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Hartsell, Bradley. "Projecting Culture Through Literary Exportation: How Imitation in Scandinavian Crime Fiction Reveals Regional Mores." Digital Commons @ East Tennessee State University, 2017. https://dc.etsu.edu/etd/3323.
Full textAbstract:
This thesis reexamines the beginnings of Swedish hardboiled crime literature, in part tracking its lineage to American culture and unpacking Swedish identity. Following the introduction, the second chapter asserts how this genre began as a form of escapism, specifically in Maj Sjöwall and Per Wahlöö’s Roseanna. The third chapter compares predecessor Raymond Chandler’s The Big Sleep with Roseanna, and how Sweden’s greater gender tolerance significantly outshining America’s is reflected in literature. The fourth chapter examines how Henning Mankell’s novels fail to fully accept Sweden’s complicity in neo-Nazism as an active component of Swedish identity. The final chapter reveals Helene Tursten’s Detective Inspector Huss engaging with gender and racial relations in unique ways, while also releasing the suppressive qualities found in the Swedish identity post-war. Therefore, this thesis will better contextualize the onset of the genre, and how its lineage reflects the fruits and the damages alike in the Swedish identity.
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Daniellou-Molinie, Celia. ""Si ça n'avait pas été vous, j'aurais eu peur". Qu'est-ce qu'incarner un personnage "méchant"? Des projections fantasmatiques au quotidien des répétitions : l'exemple du Théâtre du Soleil." Thesis, Sorbonne Paris Cité, 2017. http://www.theses.fr/2017USPCA037.
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D’Esope, acteur romain, à Heath Ledger, star hollywoodienne, de nombreuses sources rapportent des cas d’acteurs « possédés » par leur personnage de méchant. Mythes sans fondement ? Elucubrations de spectateurs en quête de frissons, voire stratégie commerciale ? Peut-être, mais là n’est pas l’essentiel : qu’elles soient véritables ou fantasmées, le nombre et la constance de ces anecdotes au fil de l’histoire en montrent bien l’importance. Notre imaginaire de spectateur semble nourri de ces dérapages fantasmés, de ces histoires d’acteurs s’étant, selon l’expression consacrée, « perdus dans leur rôle » - parfois jusqu’à en mourir.Après s’être intéressé brièvement à certaines de ces anecdotes, à ce qu'elles révèlent de notre rapport à la scène, ce travail propose un renversement de perspective : il s’agit d’interroger la possibilité d’un risque de confusion entre acteur et personnage, non plus à travers le prisme du regard porté sur le comédien, mais en s’intéressant au vécu des acteurs eux-mêmes – en tentant de se dégager des projections fantasmatiques pour essayer de comprendre ce qui se passe, réellement, « dans la tête d’un comédien » devant incarner un personnage méchant. A cette fin, nous nous intéresserons au travail de l’acteur dans ce qu'il a de plus concret, de plus anodin en apparence, du maquillage au cœur qui bat, des douleurs de genoux aux bouffées de plaisir, des rituels d’avant-spectacle aux rires ou aux larmes d’après-spectacle, des tensions à la complicité entre partenaires. Nous plongerons pour cela dans le quotidien des acteurs du Théâtre du Soleil, à travers une vaste étude de terrain mêlant observations de répétitions et entretiensFrom Aesop, the Roman actor, to Heath Ledger, the Hollywood star, numerous sources report instances of actors “possessed” by the evil part they are playing. Groundless myth, wild speculation on the part of spectators in search of thrills, or even marketing strategy? Perhaps, but that is not what matters most: whether real or fantasized, the number and the consistency of these stories throughout history bear evidence of their importance. Our imagination as a spectator seems to feed on these fantasized slips, on these stories of actors who, as the saying goes, lost themselves in acting and sometimes even died from it. After paying brief attention to some of these stories and to what they reveal about our relationship to the stage, a reversal of perspective is proposed : the risk of confusion between the actor and the character he is playing is no longer investigated through the lens of one’s perception of the actor but through paying close attention to the personal experiences of the actors themselves – we try to evade fantasies by attempting to understand what is really occurring in the actors’ mind when playing an evil character- To this end, we analyze the actor’s work in its most concrete and seemingly most innocuous aspects, from making up to the beating heart, from knee pain to flashes of pleasure, from the rituals before going on stage to laughter and tears shed once the performance is over, from tension to complicity with the partnering actors. We slip into the everyday life of the Théâtre du Soleil company by means of a wide field study which combines observation of rehearsals and actors’ statements of their own experience
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González-Mazón, Pablo. "Méthodes effectives pour les transformations birationnelles multilinéaires et contributions à l'analyse polynomiale de données." Electronic Thesis or Diss., Université Côte d'Azur, 2023. http://www.theses.fr/2023COAZ4138.
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Cette thèse explore deux sujets distincts à l'intersection de l'algèbre commutative, de la géométrie algébrique, de l'algèbre multilinéaire et de la modélisation géométrique :1. L'étude et la construction effective des transformations birationnelles multilinéaires 2. L'extraction d'informations à partir de données discrètes à l'aide de modèles polynomiaux. La partie principale de ce travail est consacrée aux transformations birationnelles multilinéaires.Une transformation birationnelle multilinéaire est une transformation rationnelle phi : (mathbb{P}^1)^n dashrightarrow{} mathbb{P}^n, définie par des polynômes multilinéaires, qui admet une transformation rationnelle inverse.Les transformations birationnelles entre espaces projectifs constituent un sujet d'étude important de la géométrie algébrique, initié par les travaux fondateurs de Cremona, qui a connu des avancées significatives au cours des dernières décennies.Plus récemment, les transformation birationnelles multiprojectives, c'est-à-dire définies par des polynômes multi-homogènes, ont récemment suscité un regain d'intérêt, motivé notamment par l'étude des structures multigraduées en algèbre commutative et leurs applications pratique en modélisation géométrique.Dans la première partie, nous étudions les aspects algébriques et géométriques des transformations birationales multilinéaires.Nous nous concentrons principalement sur les transformations birationnelles trilinéaires phi : (mathbb{P}^1)^3 dashrightarrow{} mathbb{P}^3 dont nous établissons une classification en fonction de la structure algébrique de leur espace, du lieu base, et des résolutions libres graduées minimales de l'idéal engendré par les polynômes de définition.En outre, nous développons les premières méthodes qui permettent de construire et de manipuler des transformations birationnelles non linéaires en dimension 3 avec une flexibilité suffisante pour les applications visées en modélisation géométrique.De plus, nous établissons une caractérisation de la birationalité basée sur le rang de tenseurs, qui permet de construire efficacement et ouvre la voie à l'application des outils de l'algèbre tensorielle à la birationnalité.Nous étendons également nos résultats aux transformations birationnelles multilinéaires en dimension arbitraire, dans le cas où il existe un inverse multilinéaire.Dans la deuxième partie, nous nous concentrons sur l'application des polynômes à l'analyse des données discrètes.Nous nous attaquons à deux problèmes distincts.Tout d'abord, nous dérivons des bornes pour la taille des (1-epsilon)-nets pour les ensembles de non-négativité de polynômes réels.Nos résultats nous permettent d'étendre le théorème classique du point central aux inégalités polynomiales de degré supérieur.Ensuite, nous abordons la classification des cylindres réels qui passent par cinq points qui sont tels que quatre d'entre eux sont cocycliques, c'est-à-dire qu'ils se trouvent sur un cercle.Il s'agit d'un cas particulier de problèmes plus généraux que sont la classification des racines réelles des systèmes de polynômes réels et l'extraction de primitives algébriques à partir de données brutesThis thesis explores two distinct subjects at the intersection of commutative algebra, algebraic geometry, multilinear algebra, and computer-aided geometric design:1. The study and effective construction of multilinear birational maps2. The extraction of information from measures and data using polynomialsThe primary and most extensive part of this work is devoted to multilinear birational maps.A multilinear birational map is a rational map phi: (mathbb{P}^1)^n dashrightarrow{} mathbb{P}^n, defined by multilinear polynomials, which admits an inverse rational map. Birational transformations between projective spaces have been a central theme in algebraic geometry, tracing back to the seminal works of Cremona, which has witnessed significant advancement in the last decades. Additionally, there has been a recent surge of interest in tensor-product birational maps, driven by the study of multiprojective spaces in commutative algebra and their practical application in computer-aided geometric design.In the first part, we address algebraic and geometric aspects of multilinear birational maps.We primarily focus on trilinear birational maps phi: (mathbb{P}^1)^3 dashrightarrow{} mathbb{P}^3, that we classify according to the algebraic structure of their space, base loci, and the minimal graded free resolutions of the ideal generated by the defining polynomials. Furthermore, we develop the first methods for constructing and manipulating nonlinear birational maps in 3D with sufficient flexibility for geometric modeling and design.Interestingly, we discover a characterization of birationality based on tensor rank, which yields effective constructions and opens the door to the application of tools from tensors to birationality. We also extend our results to multilinear birational maps in arbitrary dimension, in the case that there is a multilinear inverse.In the second part, our focus shifts to the application of polynomials in analyzing data and measures.We tackle two distinct problems. Firstly, we derive bounds for the size of (1-epsilon)-nets for superlevel sets of real polynomials. Our results allow us to extend the classical centerpoint theorem to polynomial inequalities of higher degree. Secondly, we address the classification of real cylinders through five-point configurations where four points are cocyclic, i.e. they lie on a circumference. This is an instance of the more general problems of real root classification of systems of real polynomials and the extraction of algebraic primitives from raw data
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Cheung, Anthony Hing-lam. "Design and implementation of an Arabic optical character recognition system." Thesis, Queensland University of Technology, 1998. https://eprints.qut.edu.au/36073/1/36073_Cheung_1998.pdf.
Full textAbstract:
Character recognition is not a difficult task for humans who repeat the process thousands of times every day as they read papers or books. However, after more than 40 years of intensive investigation, there is still no machine that can recognize alphabetic characters as well as humans. Optical Character Recognition (OCR) is the process of converting a raster image representation of a document into a format that a computer can process.
It involves many sub-disciplines of computer science including digital image processing, pattern recognition, natural language processing, artificial intelligence,
and database systems. Applications of OCR systems are broad and
include postal code recognition in postal departments, automatic document entries in companies and government departments, cheque sorting in banks, machine translation, etc. The objective of this thesis is to design an optical character recognition system
which can recognize Arabic script. This system has to be: 1) accurate: with a recognition accuracy of 953; 2) robust: able to recognize two different Arabic fonts; and 3) efficient: it should be a real time system.
This proposed system is composed of five image processing processes: 1) Image Acquisition; 2) Preprocessing; 3) Segmentation; 4) Feature Extraction; and 5) Classification. The recognized results are presented to
users via a window-based user-interface. Thus, they can control the system, recognize and edit documents by a click on the mouse button. A thinning algorithm, a word segmentation algorithm and a recognition based
character segmentation algorithm for Arabic script have been proposed to increase the recognition accuracy of the system. The Arabic word segmentation algorithm successfully segments the horizontally overlapped Arabic words, whereas the recognition-based character segmentation algorithm replaces the classical character segmentation method and raises the level of accuracy of recognition of the proposed system. These blocks have been integrated. Results to test the requirements of accuracy, robustness and efficiency are presented. Finally, some extensions to the system have also been proposed.
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Marquer, Mathieu. "Étude comparative du comportement tribologique de revêtements frottant à grande vitesse sur un alliage de titane : CoCrAlYSiBN, CuNiIn, et MAO." Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0402.
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Dans le cadre du développement d'un nouveau type de revêtement anodique pour le Ti6Al4V, l'application au pied d'aube de turboréacteur est étudiée. En cas d'impact d'un corps étranger sur l'aube, du frottement sévère peut avoir lieu entre le pied d'aube et le disque de rotor, tous deux en Ti6Al4V. Ces travaux visent à évaluer, en conditions sévères de glissement, le comportement de revêtements de référence (CoCrAlYSiBN et CuNiIn), déjà employés au niveau de ce contact, ainsi que du nouveau revêtement (MAO). Pour cela, un tribomètre spécifique a été conçu et adapté sur un banc balistique, permettant de mesurer les efforts de frottement pendant l'interaction et en déduire le coefficient de frottement moyen. L'évolution du volume usé et de la microstructure en fonction de la vitesse de glissement et de la pression de contact, a été analysée. Ceci a permis de proposer des scénarios de comportement tribologique pour les revêtements. Il a été possible de conclure de ces résultats que le revêtement MAO étudié n'est pas applicable au contact pied d'aube/disque de rotor en conditions sévères. Un modèle thermique intégrant l'abaissement du coefficient de frottement causé par le troisième corps a été développé mais nécessite encore quelques évolutions avant de pouvoir lier les conditions de glissement aux altérations microstructurales engendrées. La comparaison des propriétés thermiques aux résultats précédents a permis de proposer un mécanisme d'action, en fonction de ses propriétés, du revêtement sur les altérations thermiques et mécaniques de la pièce non-revêtue. Ces travaux de thèse ont étés réalisés dans le cadre du Projet MAO de l'IRT M2P et sont le fruit d'une collaboration entre l'IRT M2P, le LEM3, et Safran Aircraft EnginesAs part of the development of a new type of anodic coating for Ti6Al4V, its application to jet engine blades roots is studied. In the event of an impact of a foreign object on the blade, severe friction can occur between the blade root and the rotor disc, both in Ti6Al4V. This work aims to evaluate, under severe sliding conditions, the behaviour of reference coatings (CoCrAlYSiBN and CuNiIn), already applied to this contact, as well as the new coating (MAO). For this purpose, a specific tribometer was designed and adapted on a ballistic test bench, allowing to measure the friction forces during the interaction and to deduce the average friction coefficient. The wear volume and microstructure evolution was sliding speed and contact pressure, was analyzed. This led to propose tribological behaviour scenarios for coatings. From these results, it was possible to conclude that the studied MAO coating is not applicable to the blade foot/rotor disc contact under severe conditions. A thermal model incorporating the reduction of the friction coefficient caused by the third body was developed but still requires some evolutions before the sliding conditions can be linked to the microstructural alterations generated. The comparison of the thermal properties with the previous results has made it possible to propose a mechanism of action, according to its properties, of the coating on the thermal and mechanical alterations of the uncoated part. This thesis work was carried out as part of the MAO Project of IRT M2P and is the result of a collaboration between IRT M2P, LEM3, and Safran Aircraft Engines
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BIGNALET, CAZALET REMI. "Riguardo le trasformazione determinantale." Doctoral thesis, Università degli studi di Genova, 2021. http://hdl.handle.net/11567/1062495.
Full textAbstract:
Studiamo trasformazioni di Cremona determinantale, cioè trasformazioni birazionale il cui ideale di base è l'ideale dei minori massimali di una matrice Phi, via la risoluzioni dei sistemi di polinomi definiti da Phi. Usando geometria convessa, questo approccio porta in particolare a descrivere i gradi proiettivi di alcuni trasformazioni di Cremona determinantale raccolte.We study determinantal Cremona maps, i.e. birational maps whose base ideal is the maximal minors ideal of a given matrix Phi, via the resolution of the polynomials systems defined by Phi. Using convex geometry, this approach leads in particular to describe the projective degrees of some glued determinantal maps.
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Ben, marzouka Wissal. "Traitement possibiliste d'images, application au recalage d'images." Thesis, Ecole nationale supérieure Mines-Télécom Atlantique Bretagne Pays de la Loire, 2022. http://www.theses.fr/2022IMTA0271.
Full textAbstract:
Dans ce travail, nous proposons un système de recalage géométrique possibiliste qui fusionne les connaissances sémantiques et les connaissances au niveau du gris des images à recaler. Les méthodes de recalage géométrique existantes se reposent sur une analyse des connaissances au niveau des capteurs lors de la détection des primitives ainsi que lors de la mise en correspondance. L'évaluation des résultats de ces méthodes de recalage géométrique présente des limites au niveau de la perfection de la précision causées par le nombre important de faux amers. L’idée principale de notre approche proposée est de transformer les deux images à recaler en un ensemble de projections issues des images originales (source et cible). Cet ensemble est composé des images nommées « cartes de possibilité », dont chaque carte comporte un seul contenu et présente une distribution possibiliste d’une classe sémantique des deux images originales. Le système de recalage géométrique basé sur la théorie de possibilités proposé présente deux contextes : un contexte supervisé et un contexte non supervisé. Pour le premier cas de figure nous proposons une méthode de classification supervisée basée sur la théorie des possibilités utilisant les modèles d'apprentissage. Pour le contexte non supervisé, nous proposons une méthode de clustering possibiliste utilisant la méthode FCM-multicentroide. Les deux méthodes proposées fournissent en résultat les ensembles de classes sémantiques des deux images à recaler. Nous créons par la suite, les bases de connaissances pour le système de recalage possibiliste proposé. Nous avons amélioré la qualité du recalage géométrique existant en termes de perfection de précision, de diminution du nombre de faux amers et d'optimisation de la complexité temporelleIn this work, we propose a possibilistic geometric registration system that merges the semantic knowledge and the gray level knowledge of the images to be registered. The existing geometric registration methods are based on an analysis of the knowledge at the level of the sensors during the detection of the primitives as well as during the matching. The evaluation of the results of these geometric registration methods has limits in terms of the perfection of the precision caused by the large number of outliers. The main idea of our proposed approach is to transform the two images to be registered into a set of projections from the original images (source and target). This set is composed of images called “possibility maps”, each map of which has a single content and presents a possibilistic distribution of a semantic class of the two original images. The proposed geometric registration system based on the possibility theory presents two contexts: a supervised context and an unsupervised context. For the first case, we propose a supervised classification method based on the theory of possibilities using learning models. For the unsupervised context, we propose a possibilistic clustering method using the FCM-multicentroid method. The two proposed methods provide as a result the sets of semantic classes of the two images to be registered. We then create the knowledge bases for the proposed possibilistic registration system. We have improved the quality of the existing geometric registration in terms of precision perfection, reductionin the number of false landmarks and optimization of time complexity
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Yang, Liming. "Recalage robuste à base de motifs de points pseudo aléatoires pour la réalité augmentée." Thesis, Ecole centrale de Nantes, 2016. http://www.theses.fr/2016ECDN0025.
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La Réalité Augmentée (RA) vise à afficher des informations numériques virtuelles sur des images réelles. Le recalage est important, puisqu’il permet d'aligner correctement les objets virtuels dans le monde réel. Contrairement au tracking qui recale en utilisant les informations de l’image précédente, la localisation à grande échelle (wide baseline localization) calcule la solution en utilisant uniquement les informations présentes dans l’image courante. Il permet ainsi de trouver des solutions initiales au problème de recalage (initialisation) et, n’est pas sujet aux problèmes de « perte de tracking ». Le problème du recalage en RA est relativement bien étudié dans la littérature, mais les méthodes existantes fonctionnent principalement lorsque la scène augmentée présente des textures. Pourtant, pour le recalage avec les objets peu ou pas texturés, il est possible d’utiliser leurs informations géométriques qui représentent des caractéristiques plus stables que les textures. Cette thèse s’attache au problème de recalage basé sur des informations géométriques, et plus précisément sur les points. Nous proposons deux nouvelles méthodes de recalage de points (RRDM et LGC) robustes et rapides. LGC est une amélioration de la méthode RRDM et peut mettre en correspondance des ensembles de motifs de points 2D ou 3D subissant une transformation dont le type est connu. LGC présente un comportement linéaire en fonction du nombre de points, ce qui permet un tracking en temps-réel. La pertinence de LGC a été illustrée en développant une application de calibration de système projecteur-caméra dont les résultats sont comparables avec l’état de l’art tout en présentant des avantages pour l’utilisateur en termes de taille de mire de calibrationRegistration is a very important task in Augmented Reality (AR). It provides the spatial alignment between the real environment and virtual objects. Unlike tracking (which relies on previous frame information), wide baseline localization finds the correct solution from a wide search space, so as to overcome the initialization or tracking failure problems. Nowadays, various wide baseline localization methods have been applied successfully. But for objects with no or little texture, there is still no promising method. One possible solution is to rely on the geometric information, which sometimes does not vary as much as texture or color. This dissertation focuses on new wide baseline localization methods entirely based on geometric information, and more specifically on points. I propose two novel point pattern matching algorithms, RRDM and LGC. Especially, LGC registers 2D or 3D point patterns under any known transformation type and supports multipattern recognitions. It has a linear behavior with respect to the number of points, which allows for real-time tracking. It is applied to multi targets tracking and augmentation, as well as to 3D model registration. A practical method for projector-camera system calibration based on LGC is also proposed. It can be useful for large scale Spatial Augmented Reality (SAR). Besides, I also developed a method to estimate the rotation axis of surface of revolution quickly and precisely on 3D data. It is integrated in a novel framework to reconstruct the surface of revolution on dense SLAM in real-time
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Hişil, Hüseyin. "Elliptic curves, group law, and efficient computation." Thesis, Queensland University of Technology, 2010. https://eprints.qut.edu.au/33233/1/H%C3%BCseyin_Hi%C5%9Fil_Thesis.pdf.
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This thesis is about the derivation of the addition law on an arbitrary elliptic curve and efficiently adding points on this elliptic curve using the derived addition law. The outcomes of this research guarantee practical speedups in higher level operations which depend on point additions. In particular, the contributions immediately find applications in cryptology. Mastered by the 19th century mathematicians, the study of the theory of elliptic curves has been active for decades. Elliptic curves over finite fields made their way into public key cryptography in late 1980’s with independent proposals by Miller [Mil86] and Koblitz [Kob87]. Elliptic Curve Cryptography (ECC), following Miller’s and Koblitz’s proposals, employs the group of rational points on an elliptic curve in building discrete logarithm based public key cryptosystems. Starting from late 1990’s, the emergence of the ECC market has boosted the research in computational aspects of elliptic curves. This thesis falls into this same area of research where the main aim is to speed up the additions of rational points on an arbitrary elliptic curve (over a field of large characteristic). The outcomes of this work can be used to speed up applications which are based on elliptic curves, including cryptographic applications in ECC. The aforementioned goals of this thesis are achieved in five main steps. As the first step, this thesis brings together several algebraic tools in order to derive the unique group law of an elliptic curve. This step also includes an investigation of recent computer algebra packages relating to their capabilities. Although the group law is unique, its evaluation can be performed using abundant (in fact infinitely many) formulae. As the second step, this thesis progresses the finding of the best formulae for efficient addition of points. In the third step, the group law is stated explicitly by handling all possible summands. The fourth step presents the algorithms to be used for efficient point additions. In the fifth and final step, optimized software implementations of the proposed algorithms are presented in order to show that theoretical speedups of step four can be practically obtained. In each of the five steps, this thesis focuses on five forms of elliptic curves over finite fields of large characteristic. A list of these forms and their defining equations are given as follows: (a) Short Weierstrass form, y2 = x3 + ax + b, (b) Extended Jacobi quartic form, y2 = dx4 + 2ax2 + 1, (c) Twisted Hessian form, ax3 + y3 + 1 = dxy, (d) Twisted Edwards form, ax2 + y2 = 1 + dx2y2, (e) Twisted Jacobi intersection form, bs2 + c2 = 1, as2 + d2 = 1, These forms are the most promising candidates for efficient computations and thus considered in this work. Nevertheless, the methods employed in this thesis are capable of handling arbitrary elliptic curves. From a high level point of view, the following outcomes are achieved in this thesis. - Related literature results are brought together and further revisited. For most of the cases several missed formulae, algorithms, and efficient point representations are discovered. - Analogies are made among all studied forms. For instance, it is shown that two sets of affine addition formulae are sufficient to cover all possible affine inputs as long as the output is also an affine point in any of these forms. In the literature, many special cases, especially interactions with points at infinity were omitted from discussion. This thesis handles all of the possibilities. - Several new point doubling/addition formulae and algorithms are introduced, which are more efficient than the existing alternatives in the literature. Most notably, the speed of extended Jacobi quartic, twisted Edwards, and Jacobi intersection forms are improved. New unified addition formulae are proposed for short Weierstrass form. New coordinate systems are studied for the first time. - An optimized implementation is developed using a combination of generic x86-64 assembly instructions and the plain C language. The practical advantages of the proposed algorithms are supported by computer experiments. - All formulae, presented in the body of this thesis, are checked for correctness using computer algebra scripts together with details on register allocations.
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Ibrahim, Ayman Wagdy Mohamed. "Predicting glare in open-plan offices using simplified data acquisitions and machine learning algorithms." Thesis, Queensland University of Technology, 2020. https://eprints.qut.edu.au/204266/1/Ayman%20Wagdy%20Mohamed_Ibrahim_Thesis.pdf.
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Glare in open-plan offices can negatively affect the productivity and well-being of office workers. Accurate glare prediction is challenging, as occupants' sensitivity to glare may differ under the same conditions. Developed as part of an ARC Linkage Project, this thesis challenges the limitations prevalent in current glare metrics by delivering a new model of predicting glare for open-plan offices. By utilising machine learning (ML) techniques, more accurate tools and methods are unlocked to assist architects and lighting engineers in the early stages of the design process. They ultimately enable more efficient daylit office designs with reduced glare discomfort in Australia.
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Brainerd, Jeffrey Pigeon. "Interactive map projections and distortion visualization." Diss., 1998. http://catalog.hathitrust.org/api/volumes/oclc/40356530.html.
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