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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Numerical Conformal mappings for regions Bounded by Smooth Curves

Andersson, Anders January 2006 (has links)
<p>Inom många tillämpningar används konforma avbildningar för att transformera tvådimensionella områden till områden med enklare utseende. Ett exempel på ett sådant område är en kanal av varierande tjocklek begränsad av en kontinuerligt deriverbar kurva. I de tillämpningar som har motiverat detta arbete, är det viktigt att dessa egenskaper bevaras i det område en approximativ konform avbildning producerar, men det är också viktigt att begränsningskurvans riktning kan kontrolleras, särkilt i kanalens båda ändar.</p><p>Denna avhandling behandlar tre olika metoder för att numeriskt konstruera konforma avbildningar mellan ett enkelt standardområde, företrädesvis det övre halvplanet eller enhetscirkeln, och ett område begränsat av en kontinuerligt deriverbar kurva, där begränsningskurvans riktning kan kontrolleras, exakt eller approximativt.</p><p>Den första metoden är en utveckling av en idé, först beskriven av Peter Henrici, där en modifierad Schwarz-Christoffel-avbildning avbildar det övre halvplanet konformt på en polygon med rundade hörn.</p><p>Med utgångspunkt i denna idé skapas en algoritm för att konstruera avbildningar på godtyckliga områden med släta randkurvor.</p><p>Den andra metoden bygger också den på Schwarz-Christoffel-avbildningen, och utnyttjar det faktum att om enhetscirkeln eller halvplanet avbildas på en polygon kommer ett område Q i det inre av dessa, som till exempel en cirkel med centrum i origo och radie mindre än 1, eller ett område i övre halvplanet begränsat av två strålar, att avbildas på ett område R i det inre av polygonen begränsat av en slät kurva. Vi utvecklar en metod för att hitta ett polygonalt område P, utanför det Omega som man önskar att skapa en avbildning för, sådant att den Schwarz-Christoffel-avbildning som avbildar enhetscirkeln eller halvplanet på P, avbildar Q på Omega.</p><p>I båda dessa fall används tangentpolygoner för att numeriskt bestämma den önskade avbildningen.</p><p>Slutligen beskrivs en metod där en av Don Marshalls så kallade zipper-algoritmer används för att skapa en avbildning mellan det övre</p><p>halvplanet och en godtycklig kanal, begränsad av släta kurvor, som i båda ändar går mot oändligheten som räta parallella linjer.</p> / <p>In many applications, conformal mappings are used to transform two-dimensional regions into simpler ones. One such region for which conformal mappings are needed is a channel bounded by continuously differentiable curves. In the applications that have motivated this work, it is important that the region an approximate conformal mapping produces, has this property, but also that the direction of the curve can be controlled, especially in the ends of the channel.</p><p>This thesis treats three different methods for numerically constructing conformal mappings between the upper half-plane or unit circle and a region bounded by a continuously differentiable curve, where the direction of the curve in a number of control points is controlled, exact or approximately.</p><p>The first method is built on an idea by Peter Henrici, where a modified Schwarz-Christoffel mapping maps the upper half-plane conformally on a polygon with rounded corners. His idea is used in an algorithm by which mappings for arbitrary regions, bounded by smooth curves are constructed.</p><p>The second method uses the fact that a Schwarz-Christoffel mapping from the upper half-plane or unit circle to a polygon maps a region Q inside the half-plane or circle, for example a circle with radius less than 1 or a sector in the half--plane, on a region Omega inside the polygon bounded by a smooth curve. Given such a region Omega, we develop methods to find a suitable outer polygon and corresponding Schwarz-Christoffel mapping that gives a mapping from Q to Omega.</p><p>Both these methods use the concept of tangent polygons to numerically determine the coefficients in the mappings.</p><p>Finally, we use one of Don Marshall's zipper algorithms to construct conformal mappings from the upper half--plane to channels bounded by arbitrary smooth curves, with the additional property that they are parallel straight lines when approaching infinity.</p>
32

Simulation de la variabilité du transistor MOS

Lemoigne, Pascal 01 December 2011 (has links)
L’augmentation de la densité d’intégration des circuits intégrés nous a amené à étudier, dans le cadre du développement de la technologie CMOS 45 nm, les sources de variabilité inhérentes aux procédés de fabrication utilisés pour ce nœud technologique, et à en déterminer les composantes principales,dans le but ultime de permettre la simulation précise de l’impact de la variabilité technologique à la fois au niveau transistor et circuit. Après un état de l’art des sources de variabilité du transistor MOS et des moyens de simulation associés,ce travail s'est orienté sur les fluctuations d'un facteur technologique difficilement accessible à la mesure statistique qu'est le dopage canal. Ensuite le nœud 45 nm a été étudié expérimentalement via un plan d'expériences.Ceci a permis de connaitre les variations naturelles des facteurs technologiques mais surtout les sensibilités des performances électriques vis-à-vis de ces facteurs.Nous avons pu ainsi identifier les causes prépondérantes de variabilité dues au procédé.Enfin, nous proposons d’améliorer la prise en compte des déviations des facteurs process dans les simulations Monte-Carlo et pire-cas appliquées aux modèles compacts au regard de ces observations expérimentales. / Continuous improvement in integrated circuits density of integration lead us to study process-induced variations in the framework of the 45 nm node, and to determine their principal contributions with the ultimate goal being to allow an accurate simulation of both transistor and circuit level variability. This work starts with a study of the state of the art of variability sources of the MOS transistor and associated simulation means. Then it focuses on the fluctuations of the channel doping, which is a difficult factor to measure statistically.After that we study the 45 nm node through a design of experiment which let us learn about natural variations of process factors but mostly about electrical performances sensitivity to those factors.Thanks to that we could identify major causes of process-induced variability at this stage of this node development. At last, with respect to those experimental results, we propose to enhance the taking in account of process variations in Monte-Carlo and corner simulations applied to compact models.
33

Abordagem wavelet para detecÃÃo de cantos em formas / Wavelet boarding for detention of corners in forms

IÃlis Cavalcante de Paula JÃnior 26 March 2007 (has links)
CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / A anÃlise de formas representa um papel importante em aplicaÃÃes de visÃo computacional e processamento de imagens, e a representaÃÃo da forma à o primeiro passo para esta anÃlise. Esta presente dissertaÃÃo discute e aborda um conjunto de tÃcnicas disponÃveis na literatura para a geraÃÃo de uma representaÃÃo adequada de formas baseada em cantos. A abordagem proposta provà uma decomposiÃÃo wavelet nÃo-decimada do contorno representado pelo sinal de angulaÃÃo e curvatura afim de representar uma forma por seus pontos mais relevantes sem requerer intervenÃÃo do usuÃrio. A metodologia adotada apresenta resultados promissores, faz uso de ferramentas disponÃveis na literatura e elimina caracterÃsticas redundantes da forma com o intuito de alcanÃar uma representaÃÃo que mantenha uma reconstruÃÃo adequada da forma original. Uma nova medida de avaliaÃÃo, sob o aspecto do erro obtido na reconstruÃÃo, tambÃm à apresentada de modo a confirmar que o algoritmo proposto realiza com sucesso a sua meta e supera os detectores de cantos utilizados para testes e comparaÃÃes. / Shape analysis plays an important role in computer vision and image processing applications and shape representation is the first step towards it. The current dissertation discusses a set of techniques available in the literature in order to generate an adequate shape representation based on corners. The proposed approach provides an non-decimated wavelet decomposition of the represented contour by curvature and angulation signals in order to represent the shape using the most relevant contour points without requiring any user intervention. The adopted methodology presents promising results and it uses a set of tools, with little highlight in the literature, and it eliminates the redundant shape features in order to accomplish the suitable representation of the original shape. A novel evaluation measure, concerning the reconstruction error, is also presented to confirm that the proposed algorithm achieves its goal and outperforms other corner detectors used for tests and comparison.
34

Numerical Conformal mappings for regions Bounded by Smooth Curves

Andersson, Anders January 2006 (has links)
Inom många tillämpningar används konforma avbildningar för att transformera tvådimensionella områden till områden med enklare utseende. Ett exempel på ett sådant område är en kanal av varierande tjocklek begränsad av en kontinuerligt deriverbar kurva. I de tillämpningar som har motiverat detta arbete, är det viktigt att dessa egenskaper bevaras i det område en approximativ konform avbildning producerar, men det är också viktigt att begränsningskurvans riktning kan kontrolleras, särkilt i kanalens båda ändar. Denna avhandling behandlar tre olika metoder för att numeriskt konstruera konforma avbildningar mellan ett enkelt standardområde, företrädesvis det övre halvplanet eller enhetscirkeln, och ett område begränsat av en kontinuerligt deriverbar kurva, där begränsningskurvans riktning kan kontrolleras, exakt eller approximativt. Den första metoden är en utveckling av en idé, först beskriven av Peter Henrici, där en modifierad Schwarz-Christoffel-avbildning avbildar det övre halvplanet konformt på en polygon med rundade hörn. Med utgångspunkt i denna idé skapas en algoritm för att konstruera avbildningar på godtyckliga områden med släta randkurvor. Den andra metoden bygger också den på Schwarz-Christoffel-avbildningen, och utnyttjar det faktum att om enhetscirkeln eller halvplanet avbildas på en polygon kommer ett område Q i det inre av dessa, som till exempel en cirkel med centrum i origo och radie mindre än 1, eller ett område i övre halvplanet begränsat av två strålar, att avbildas på ett område R i det inre av polygonen begränsat av en slät kurva. Vi utvecklar en metod för att hitta ett polygonalt område P, utanför det Omega som man önskar att skapa en avbildning för, sådant att den Schwarz-Christoffel-avbildning som avbildar enhetscirkeln eller halvplanet på P, avbildar Q på Omega. I båda dessa fall används tangentpolygoner för att numeriskt bestämma den önskade avbildningen. Slutligen beskrivs en metod där en av Don Marshalls så kallade zipper-algoritmer används för att skapa en avbildning mellan det övre halvplanet och en godtycklig kanal, begränsad av släta kurvor, som i båda ändar går mot oändligheten som räta parallella linjer. / In many applications, conformal mappings are used to transform two-dimensional regions into simpler ones. One such region for which conformal mappings are needed is a channel bounded by continuously differentiable curves. In the applications that have motivated this work, it is important that the region an approximate conformal mapping produces, has this property, but also that the direction of the curve can be controlled, especially in the ends of the channel. This thesis treats three different methods for numerically constructing conformal mappings between the upper half-plane or unit circle and a region bounded by a continuously differentiable curve, where the direction of the curve in a number of control points is controlled, exact or approximately. The first method is built on an idea by Peter Henrici, where a modified Schwarz-Christoffel mapping maps the upper half-plane conformally on a polygon with rounded corners. His idea is used in an algorithm by which mappings for arbitrary regions, bounded by smooth curves are constructed. The second method uses the fact that a Schwarz-Christoffel mapping from the upper half-plane or unit circle to a polygon maps a region Q inside the half-plane or circle, for example a circle with radius less than 1 or a sector in the half--plane, on a region Omega inside the polygon bounded by a smooth curve. Given such a region Omega, we develop methods to find a suitable outer polygon and corresponding Schwarz-Christoffel mapping that gives a mapping from Q to Omega. Both these methods use the concept of tangent polygons to numerically determine the coefficients in the mappings. Finally, we use one of Don Marshall's zipper algorithms to construct conformal mappings from the upper half--plane to channels bounded by arbitrary smooth curves, with the additional property that they are parallel straight lines when approaching infinity.
35

Matching Feature Points in 3D World

Avdiu, Blerta January 2012 (has links)
This thesis work deals with the most actual topic in Computer Vision field which is scene understanding and this using matching of 3D feature point images. The objective is to make use of Saab’s latest breakthrough in extraction of 3D feature points, to identify the best alignment of at least two 3D feature point images. The thesis gives a theoretical overview of the latest algorithms used for feature detection, description and matching. The work continues with a brief description of the simultaneous localization and mapping (SLAM) technique, ending with a case study on evaluation of the newly developed software solution for SLAM, called slam6d. Slam6d is a tool that registers point clouds into a common coordinate system. It does an automatic high-accurate registration of the laser scans. In the case study the use of slam6d is extended in registering 3D feature point images extracted from a stereo camera and the results of registration are analyzed. In the case study we start with registration of one single 3D feature point image captured from stationary image sensor continuing with registration of multiple images following a trail. Finally the conclusion from the case study results is that slam6d can register non-laser scan extracted feature point images with high-accuracy in case of single image but it introduces some overlapping results in the case of multiple images following a trail.
36

The development of a Hardware-in-the-Loop test setup for event-based vision near-space space objects.

van den Boogaard, Rik January 2023 (has links)
The purpose of this thesis work was to develop a Hardware-in-the-Loop imaging setup that enables experimenting with an event-based and frame-based camera under simulated space conditions. The generated data sets were used to compare visual navigation algorithms in terms of an event-based and frame-based feature detection and tracking algorithm. The comparative analyses of the feature detection and tracking algorithms were used to get insights into the feasibility of event-based vision near-space space objects. Event-based cameras differ from frame-based cameras by how they produce an asynchronous and independent stream of events caused by brightness changes at each pixel instead of capturing images at a fixed rate. The setup design is based on a theoretical framework incorporating optical calculations. These calculations indicating the asteroid model needed to be scaled down by a factor of 3192 to fit inside the camera depth-of-view. This resulted in a scaled Bennu asteroid with a size of 16.44 centimeters.The cameras under testing conducted three experiments to generate data sets. The utilization of a feature detection and tracking algorithm on both camera data sets revealed that the absolute number of tracked features, computation time, and robustness in various scenarios of the frame-based camera algorithm outperforms the event-based camera algorithm. However, when considering the percentages of tracked features relative to the total detected features, the event-based algorithm tracks a significantly higher percentage of features for at least one key frame than the frame-based algorithm.  The comparative analysis of the experiments performed in space-simulated conditions during this project showed that the feasibility of an event-based camera using solely events is low compared to the frame-based camera.
37

Eclogites and eclogites: Oxygen isotope evidence of a shared subduction origin for Franciscan eclogites and Moses Rock eclogite xenoliths

Hoover, William F. 03 June 2014 (has links)
No description available.
38

The Role of Peripheral Vision in Configural Spatial Knowledge Acquisition

Douglas, Lisa J. 19 June 2017 (has links)
No description available.
39

ALGORITHMS FOR LAYOUT-AWARE AND PERFORMANCE MODEL DRIVEN SYNTHESIS OF ANALOG CIRCUITS

AGARWAL, ANURADHA January 2005 (has links)
No description available.
40

Modélisation et méta-analyse des effets du domaine d’action motrice pratiqué sur la conduite et la prise de décision motrices des sportifs : étude quasi-expérimentale au moyen d’un modèle de simulation électronique et numérique / Modeling and meta-analysis of motor domain practice effect's on motor activities and decision-making of athletes : quasi-experimental study using a numeric and electronic simulation model

Ben Ali, Boubaker 06 December 2018 (has links)
Les contraintes liées au système de signes véhiculés par le comportement humain multiplient les difficultés face à toutes les formes d‘analyses, particulièrement celles qui se fondent sur l‘observation. Par exemple, les jeux sportifs peuvent, par leur richesse et leur complexité, restreindre le jugement de l‘observateur, notamment lorsqu‘il s‘agit d‘étudier des conduites et des prises de décisions motrices in situ, là où le pratiquant évolue dans un rapport consubstantiel avec son environnement. C‘est à ce niveau que les recherches en praxéologie proposent l‘analyse de la logique interne des situations ludosportives à travers une démarche systémique et structurale et une classification de pratiques sportives et ludomotrices en huit domaines d‘action motrice distincts. Les poutres maîtresses de ces domaines d‘action sont : la nature du rapport du sujet avec le milieu physique (milieu certain ou incertain) ainsi que la présence d‘interaction motrice liée à la présence d‘adversaires et/ou de partenaires. Nous avons mené une méta-analyse de trois domaines d‘action motrice au coeur desquels les sportifs pratiquent dans un milieu domestiqué, dont un domaine psychomoteur (agir en solo) et deux domaines sociomoteurs (agir contre des adversaires et agir avec des partenaires et des adversaires). Nous avons adopté une démarche méthodologique qui fait appel à l‘outil de modélisation électronique et numérique. Ce travail s‘articule autour de la science de l‘action motrice, des sciences de l‘Éducation, de la didactique des APS et des sciences de l‘ingénierie électronique et numérique. La problématique tente de mettre en évidence les effets potentiels d‘une pratique motrice régulière de trois domaines d‘action distincts sur les conduites et les prises de décision motrices. Autrement dit, chaque domaine d‘action motrice comprend des activités ludomotrices homogènes au regard de leurs traits de logique interne, influençant ainsi certains schémas d‘actions spécifiques sur la conduite motrice du pratiquant, propices au façonnage d‘habitus moteurs. Les investigations se construisent autour d‘un modèle expérimental spécifique appelé « B-percept® », modèle créé à partir d‘un jeu ludomoteur traditionnel, le « jeu des Quatre coins ». Ce système de mesures innovant et évolutif est utilisé pour évaluer et comparer les conduites de sportifs des trois domaines précités et de non-sportifs. Le protocole B-percept® mesure la vitesse de réaction simple et complexe, tant visuelle que sonore des pratiquants. Par ailleurs, outre les observations des sportifs agissants, nous avons proposé des tests de prédictions de score et d‘estime de soi (PSPP) et un entretien post-test avec les sujets, ceci afin de mieux appréhender et comprendre les conduites motrices exécutées. Les résultats obtenus ont montré qu‘une pratique sportive influencerait de manière positive le temps de réaction simple et complexe des sportifs par rapport aux non-pratiquants de sports. De surcroit, elle pourrait développer significativement leur sentiment d‘auto-efficacité, ce qui se traduirait par une meilleure capacité de prédiction des scores dans les tests B-percept®. Globalement, on relève aussi des résultats plus tranchés entre les domaines sociomoteur et psychomoteur, notamment dans la prise de décision au cours des situations complexes. Ces résultats ont été vérifiés à travers une méta-analyse par domaines, par algorithme moteur et par habitus moteurs. Fort de ces résultats, le modèle B-percept® pourra trouver des extensions dans le domaine de l‘enseignement en éducation physique et sportive, de l‘entrainement sportif et dans les centres de formation des élèves à besoins spécifiques. Dans le champ de l‘EPS, notre objectif est de contribuer à la réflexion et à la conception des contenus et de la programmation des activités physiques et sportives en ciblant, de façon pertinente et cohérente, les choix des situations motrices selon les domaines d‘action ludomotrice. / In sports and physical activities, gestures often carry an affective connotation. However the constraints due to their complexity when used in the communication process as signs system produced by human behavior could multiply difficulties on the of scientific analyses and studies. Thus, methods used to interpret the human movements and gestures have evolved in last decades, due to an increasing use of quantitative data. Nowadays researchers are working on decision-making by collecting behavioral significant information, especially during human-interactions in sports activities. Thus, since more than forty years, researches such as in motor praxeology analysis the internal logic of sports practices through systemic and structural analyses. Consequently a classification of sports activities was raised and gave eight different domains of motor action. These domains are based on the nature of physical environment (certain or uncertain environment), the attendance of opponents and/or partners. The aim of this thesis is to propose a systemic and structural methodological approach by comparing through a meta-analysis the impact of a regular sports practice in three different domains of motor activities on motor-behavior and decision-making. Our approach is built on an experimental model previously established by modeling the paradoxal game called the ―four corners game‖. Thus a smart wireless system for modeling visual and auditory searching behavior was conceived for measuring simple and complex reaction time. B-percept® helps as well to make observations, self-efficacy survey, test score-predictions and personal self-physical profile. This research allowed us to find relevant results. However, we need to be cautious about their generalization. Indeed, we have found that practicing sport positively influences the simple and complex reaction times and significantly increases self-efficacy of sports practitioners. Moreover, they could have a better ability to predict their scores at B-percept® tests. Meta-analysis through sports specialties and habitus were proceeded to improve results‘ analyzes, however, we still needing several investigations through future researches to propose a generalization of the equation model of B-percept®. In the near future, this experimental new model will be available for researchers in physical education and sports, teachers and coaches. It could also be proposed to training centers for students with special needs (handicap). We are looking forward helping to improve scholar programs made from sports activities as to be classified through the domain of actions.

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