nÃo hà / Modelos baseados em splats tÃm ganhado crescente atenÃÃo devido a seu potencial para renderizaÃÃes de modelos geomÃtricos complexos de forma eficiente e com alta qualidade. A ausÃncia de informaÃÃes de conectividade desses modelos permite operaÃÃes de modelagem complexas, como operaÃÃes booleanas, e fraturas em simulaÃÃes fÃsicas. Entretanto, essas operaÃÃes geralmente geram modelos com arestas e cantos que nÃo podem ser representados corretamente com um nÃmero finito de splats sem que um tratamento seja feito. Neste trabalho, um grafo de vizinhanÃa utiliza uma estimativa que garante a conexÃo de todos os splats presentes em lados opostos de uma descontinuidade e que precisam ser recortados uns contra os outros. ApÃs utilizar um mÃtodo de detecÃÃo de descontinuidades no grafo gerado, os vizinhos que participam do recorte de um splat, os clip partners, sÃo determinados e classificados para que recortem o splat de forma a adaptÃ-lo à curva da descontinuidade. Outro problema encontrado na renderizaÃÃo de modelos baseados em splats à reconstruÃÃo de superfÃcies intersectantes. Nas proximidades de interseÃÃes de superfÃcies, as superfÃcies sÃo misturadas, resultando em artefatos. Para tratar esses casos, um algoritmo de segmentaÃÃo realiza a separaÃÃo das diversas superfÃcies presentes no modelo, identificando os splats que as formam e impedindo que eles sejam combinados em Ãreas prÃximas de interseÃÃes de superfÃcies na etapa de reconstruÃÃo da superfÃcie em espaÃo de imagem / Splats based models have gained increasing attention due to its potential for rendering complex geometric models efficiently and with high quality. The absence connectivity information of these models allows complex modeling operations, as Boolean operations, and fractures in physics simulations. However, these operations often generate models with edges and corners that can not be represented correctly with a finite number of splats without a treatment to be done. In this work, a neighborhood graph uses an estimate which ensures the connection of all these splats on opposite sides a discontinuity and that need to be clipped against each other. After using a method for detecting discontinuities in the generated graph, the neighbors participating in the a splat clipping, clip partners are determined to cut out and sorted splat so as to adapt it to the curve of discontinuity. Another problem encountered in rendering models based on reconstruction of splats is intersecting surfaces. Close intersections of surfaces, the surfaces are mixed, resulting in artifacts. to treat these cases, a segmentation algorithm performs separation of the various surfaces present in the model, identifying the splats that form and hold them to be combined into areas near the intersections of surfaces in the surface reconstruction phase space image

No / Using SANS to map the deformation of individual polymer chains in the vicinity of re-entrant corners in a contraction−expansion flow, we show that stress singularities at such corners, predicted by formulations of fluid dynamics that lack a molecular basis, do not cause extreme deformation of the chains. Multiscale modeling based on a nonlinear tube theory incorporating appropriate relaxation processes quantitatively reproduces the observed scattering, thus providing further evidence for the universality of the tube model for polymer flow.

Rico strata are recognised throughout the Four Corners region of southwestern Colorado, southeastern Utah, northeastern Arizona, and northwestern New Mexico. The term Rico has been applied to a group of strata which exhibit a lateral and vertical transition between two contrasting environments, the marine Hermosa and the non-marine Cutler. Two faunal provinces reflect these widely diverse conditions of sedimentation. However, few fossils of diagnostic value have been discovered despite the abundance of fossiliferous strata within the Rico. Rico strata are believed to range between Desmoinesian and Virgilian in age. Lithofacies data on the Rico were assembled from literature, outcrop sections, and various well logs. These data were then compiled on an isopach-lithofacies map. The isopach-lithofacies map shows the thickness trends and the lithologic variations of Rico strata throughout the region of study. The tectonic framework of the region is reconstructed from the isopach-lithofacies map and mechanical analyses of the elastic strata. Clastic material in the Rico increases in average grain size from west to east toward the Uncomphagre Uplift suggest that this area was actively positive during Rico time. The vertical variation of normal marine limestone and clastic red beds in the Rico reflect an alternately transgressing and regressing sea over much of the Four Corners region. This intricate intertonguing of normal marine limestone and clastic red beds probably resulted from deposition in a shallow basin on an unstable shelf. The occurrence of oil, gas, and cement quality limestone in the Rico is examined from an economic aspect. A. brief review of the general geology and geologic history of tile region is also included.

No description available.

Coal-fueled energy development in the Southwest has resulted in a controversy over claims of environmental damage and spiritual and social disruption to the Native American inhabitants of the region. Development has been supported through estimates of the economic benefits that will accrue to the Hopi and Navajo through the planned development. This research has developed a modeling approach to systematically and rationally assess the impacts of energy development on the Hopi and Navajo Tribes. The model incorporates a simulation technique that describes the Indian social systems over time with and without energy development. The variations within the system without energy development and with various levels of development allow insights into impacts. Computer control allows the model to consider many different decisions relative to energy development, and incorporated graphics allow for efficient and fast impact interpretation. The results of the model indicate that proposed impacts on the Native Americans have been exaggerated. Neither the economic impacts nor spiritual disruptions claimed are seen to occur. The model is seen to be a valuable tool for systematic analysis and the presentation of social impact information.

Unsteady shock wave propagation through ducts has many applications, ranging from blast wave shelter design to advanced high-speed propulsion systems. The research objective of this study was improved fundamental understanding of the transient flow structures during unsteady shock wave propagation through rectangular ducts with varying cross-sectional area. This research focused on the fluid dynamics of the unsteady shock-induced flow fields, with an emphasis placed on understanding and characterizing the mechanisms behind flow compression (wave structures), flow induction (via shock waves), and enhanced mixing (via shock-induced viscous shear layers). A theoretical and numerical (CFD) parametric study was performed, in which the effects of these parameters on the unsteady flow fields were examined: incident shock strength, area ratio, and viscous mode (inviscid, laminar, and turbulent). Two geometries were considered: the backward-facing step (BFS) geometry, which provided a benchmark and conceptual framework, and the splitter plate (SP) geometry, which was a canonical representation of the engine flow path. The theoretical analysis was inviscid, quasi-1D and quasi-steady; and the computational analysis was fully 2D, time-accurate, and viscous. The theory provided the wave patterns and primary wave strengths for the BFS geometry, and the simulations verified the wave patterns and quantified the effects of geometry and viscosity. It was shown that the theoretical wave patterns on the BFS geometry can be used to systematically analyze the transient, 2D, viscous flows on the SP geometry. This work also highlighted the importance and the role of oscillating shock and expansion waves in the development of these unsteady flows. The potential for both upstream and downstream flow induction was addressed. Positive upstream flow induction was not found in this study due to the persistent formation of an upstream-moving shock wave. Enhanced mixing was addressed by examining the evolution of the unsteady shear layer, its instability, and their effects on the flow field. The instability always appeared after the reflected shock interaction, and was exacerbated in the laminar cases and damped out in the turbulent cases. This research provided new understanding of the long-term evolution of these confined flows. Lastly, the turbulent work is one of the few turbulent studies on these flows.

L’interprétation du contenu de l’image est un objectif très important dans le traitement de l’image et la vision par ordinateur. Par conséquent, plusieurs chercheurs y sont intéressés. Une image contient des informations multiples qui peuvent être étudiés, telles que la couleur, les formes, les arêtes, les angles, la taille et l’orientation. En outre, les contours contiennent les structures les plus importantes de l’image. Afin d’extraire les caractéristiques du contour d’un objet, nous devons détecter les bords de cet objet. La détection de bords est un point clé dans plusieurs applications, telles que :la restauration, l’amélioration de l’image, la stéganographie, le filigrane, la récupération, la reconnaissance et la compression de l’image, etc. Toutefois, l’évaluation de la performance de la méthode de détection de bords reste un grand défi. Les images numériques sont parfois modifiées par une procédure légale ou illégale afin d’envoyer des données secrètes ou spéciales. Afin d’être moins visibles, la plupart des méthodes stéganographiques modifient les valeurs de pixels dans les bords/textures de parties de l’image. Par conséquent, il est important de détecter la présence de données cachées dans les images numériques. Cette thèse est divisée principalement en deux parties.La première partie discute l’évaluation des méthodes de détection des bords du filtrage, des contours et des angles. En effet, cinq contributions sont présentées dans cette partie : d’abord, nous avons proposé un nouveau plan de surveillance normalisée de mesure de la qualité. En second lieu, nous avons proposé une nouvelle technique pour évaluer les méthodes de détection des bords de filtrage impliquant le score minimal des mesures considérées. En plus, nous avons construit une nouvelle vérité terrain de la carte de bords étiquetée d’une manière semi-automatique pour des images réelles.En troisième lieu, nous avons proposé une nouvelle mesure prenant en compte les distances de faux points positifs pour évaluer un détecteur de bords d’une manière objective. Enfin, nous avons proposé une nouvelle approche de détection de bords qui combine la dérivée directionnelle et l’homogénéité des grains. Notre approche proposée est plus stable et robuste au bruit que dix autres méthodes célèbres de détection. La seconde partie discute la stéganalyse de l’image en couleurs, basée sur l’apprentissage automatique (machine learning). En effet, trois contributions sont présentées dans cette partie : d’abord, nous avons proposé une nouvelle méthode de stéganalyse de l’image en couleurs, basée sur l’extraction de caractéristiques de couleurs à partir de corrélations entre les gradients de canaux rouge, vert et bleu. En fait, ces caractéristiques donnent le cosinus des angles entre les gradients. En second lieu, nous avons proposé une nouvelle méthode de stéganalyse de l’image en couleurs, basée sur des mesures géométriques obtenues par le sinus et le cosinus des angles de gradients entre tous les canaux de couleurs. Enfin, nous avons proposé une nouvelle méthode de stéganalyse de l’image en couleurs, basée sur une banque de filtres gaussiens orientables. Toutes les trois méthodes proposées présentent des résultats intéressants et prometteur en devançant l’état de l’art de la stéganalyse en couleurs. / Interpretation of image contents is very important objective in image processing and computer vision. Wherefore, it has received much attention of researchers. An image contains a lot of information which can be studied such as color, shapes, edges, corners, size, and orientation. Moreover, contours include the most important structures in the image. In order to extract features contour of an object, we must detect the edges of that object. Edge detection results, remains a key point and very important step in wide range of applications such as: image restoration, enhancement, steganography, watermarking, image retrieval, recognition, compression, and etc. An efficient boundary detection method should create a contour image containing edges at their correct locations with a minimum of misclassified pixels. However, the performance evaluationof the edge detection results is still a challenging problem. The digital images are sometimes modify by a legal or illegal data in order to send special or secret data. These changes modify slight coefficient values of the image. In order to be less visible, most of the steganography methods modify the pixel values in the edge/texture image areas. Therefore, it is important to detect the presence of hidden data in digital images. This thesis is divided mainly into two main parts. The first part, deals with filtering edge detection, contours evaluation and corners detection methods. More deeply, there are five contributions are presented in this part: first, proposed a new normalized supervised edge map quality measure. The strategy to normalize the evaluation enables to consider a score close to 0 as a good edge map, whereas a score 1 translates a poor segmentation. Second, proposed a new technique to evaluate filtering edge detection methods involving the minimum score of the considerate measures. Moreover, build a new ground truth edge map labelled in semi-automatic way in real images. Third, proposed a new measure takes into account the distances of false positive points to evaluate an edge detector in an objective way. Finally, proposed a new approach for corner detection based on the combination of directional derivative and homogeneity kernels. The proposed approach remains more stable and robust to noise than ten famous corner detection methods. The second part, deals with color image steganalysis, based on a machine learning classification. More deeply, there are three contributionsare presented in this part: first, proposed a new color image steganalysis method based on extract color features from correlations between the gradients of red, green and blue channels. Since these features give the cosine of angles between gradients. Second, proposed a new color steganalysis method based on geometric measures obtained by the sine and cosine of gradient angles between all the color channels. Finally, proposed a new approach for color image steganalysisbased on steerable Gaussian filters Bank.All the three proposed methods in this part, provide interesting and promising results by outperforming the state-of-art color image steganalysis.

Dans cette thèse, nous étudions les propriétés spectrales du Laplacien avec la condition de bord de Robin attractive sur des domaines du plan à coins. Notre but est de comprendre l’influence des coins convexes sur l’asymptotique des valeurs propres de cet opérateur lorsque le paramètre de Robin est grand. Nous montrons en particulier que l’asymptotique des premières valeurs propres de Robin sur des polygones curvilignes est déterminée par des opérateurs modèles : les Laplaciens agissant sur les secteurs tangents au domaine. Pour une certaine classe de polygones droits, nous montrons l’existence d’un opérateur effectif sur le bord du domaine qui détermine l’asymptotique des valeurs propres suivantes. Enfin, des asymptotiques de Weyl pour différents seuils dépendant du paramètre de Robin sont obtenues. / In this thesis, we are interested in the spectral properties of the Laplacian with the attractive Robin boundary condition on planar domains with corners. The aim is to understand the influence of the convex corners on the spectral properties of this operator when the Robin parameter is large. In particular, we show that the asymptotics of the first Robin eigenvalues on curvilinear polygons is determined by model operators: the Robin Laplacians acting on infinite sectors. For a particular class of polygons with straight edges, we prove the existence of an effective operator acting on the boundary of the domain and determining the asymptotics of the further eigenvalues. Finally, some Weyl-type asymptotics for different thresholds depending on the Robin parameter are obtained.

No description available.

<p>The main contributions of this thesis include two points: firstly, we originally establish Complex STM to semi-analytically calculate the mode profiles of multi-layer planar waveguide terminated with both PML and PRB ; secondly, although CMMM has been generally applied to the simulation of waveguide facets, Bragg gratings, etc[52-53], we for the first time demonstrate that CMMM can also be utilized for the modeling of couplings of radiation field outgoing perpendicularly to the waveguide axis with an incident wave launched in the examples of high-index-contrast waveguide crossings and corners. CMMM is proved to be able to estimate the field profiles and power flows accurately through the validation with FDTD.</p> / <p>Optical waveguides are basic building blocks of high-density photonic integrated circuits and play crucial roles in optical access networks, biomedical system, sensors and so on. Various kinds of dielectric waveguides apply the total internal reflection condition to transmit optical field [9] and even more complicated structures based on waveguide interconnects, Bragg grating, photonic crystals are actively developed by corporations and academic institutes. Especially, the fast developing pace of Metal-Organic Chemical Vapor Deposition (MOCVD), Molecular Beam Epitaxy (MBE) and other fabrication techniques has predicted the increasing complication and thus more advanced function of modern optics integrated circuits. Under such circumstances, convenient and accurate modeling and simulation schemes are necessary for the exploration, designing and optimization of photonic devices, systems and networks before the time-consuming and expensive fabrication process.</p> <p>The thesis summarizes several frequency-domain modeling schemes for the calculation of mode profile or beam propagation in 2D dielectric waveguide. The thesis mainly covers conventional Smooth Transition Method (STM), High Order Finite Difference (HOFD) scheme, Complex STM, and Complex Mode Matching Method (CMMM) based on the 2D waveguide model terminated with Perfect Matching Layer (PML) and Perfect Reflection Boundary (PRB). The mode spectrums and modal patterns obtained from Complex STM are compared with those of HOFD, and the simulation of waveguide crossings and corners with CMMM is validated with Finite-Difference-Time-Domain (FDTD) Method.</p> <p><strong> </strong></p> / Master of Applied Science (MASc)