Considerações de informação perceptual têm ganhado espaço rapidamente em pesquisas referentes a representação, análise e exibição de malhas. Estudos com usuários, eye tracking e outras técnicas são capazes de fornecer informações cada vez mais úteis para sistemas voltados a usuário, que formam a maioria das aplicações em computação gráfica. Neste trabalho nós expandimos sobre o conceito de Saliência de Malhas — uma medida automática de importância visual para malhas de triângulos baseada em modelos de atenção humana em baixo nível — melhorando, extendendo e realizando integração com diferentes aplicações. Nós extendemos o conceito de Saliência de Malhas para englobar objetos deformáveis, mostrando como um mapa de saliência em nível de vértice pode ser construído capturando corretamente regiões de alta importância perceptual através de um conjunto de poses ou deformações. Nós definimos saliência multi-pose como um agregado multi-escala de valores de curvatura sobre uma vizinhança localmente estável, em conjunto com deformações desta vizinhança em múltiplas poses. Nós substituímos distância Euclideana por geodésica, assim fornecendo melhores estimativas de vizinhança local. Resultados mostram que saliência multi-pose gera resultados visualmente mais interessantes em simplificações quando comparado à saliência em uma única pose. Nós também aplicamos saliência de malhas ao problema de segmentação e rendering dependente de ponto de vista, introduzindo uma técnica para segmentação que particiona um objeto em um conjunto de clusters, cada um englobando um grupo de características localmente interessantes. Saliência de malhas é incorporada em um framework para clustering propagativo, guiando seleção de pontos de partida para clusters e custos de propagação de faces, levando a uma convergência de clusters ao redor de características perceptualmente importantes. Nós comparamos nossa técnica com diferentes métodos automáticos para segmentação, mostrando que ela fornece segmentação melhor ou comparável sem necessidade de intervenção do usuário. Uma vez que o algoritmo de segmentação proposto é especialmente aplicável a rendering multi-resolução, nós ilustramos uma aplicação do mesmo através de um sistema de rendering baseado em ponto de vista guiado por saliência, alcançando melhorias consideráveis em framerate com muito pouca perda de qualidade visual. / Considerations on perceptual information are quickly gaining importance in mesh representation, analysis and display research. User studies, eye tracking and other techniques are able to provide ever more useful insights for many user-centric systems, which form the bulk of computer graphics applications. In this work we build upon the concept of Mesh Saliency — an automatic measure of visual importance for triangle meshes based on models of low-level human visual attention—improving, extending and integrating it with different applications. We extend the concept of Mesh Saliency to encompass deformable objects, showing how a vertex-level saliency map can be constructed that accurately captures the regions of high perceptual importance over a range of mesh poses or deformations. We define multipose saliency as a multi-scale aggregate of curvature values over a locally stable vertex neighborhood together with deformations over multiple poses. We replace the use of the Euclidean distance by geodesic distance thereby providing superior estimates of the local neighborhood. Results show that multi-pose saliency generates more visually appealing mesh simplifications when compared to a single-pose mesh saliency. We also apply Mesh Saliency to the problem of mesh segmentation and view-dependent rendering, introducing a technique for segmentation that partitions an object into a set of face clusters, each encompassing a group of locally interesting features. Mesh Saliency is incorporated in a propagative mesh clustering framework, guiding cluster seed selection and triangle propagation costs and leading to a convergence of face clusters around perceptually important features. We compare our technique with different fully automatic segmentation algorithms, showing that it provides similar or better segmentation without the need for user input. Since the proposed clustering algorithm is specially suitable for multi-resolution rendering, we illustrate application of our clustering results through a saliency-guided view-dependent rendering system, achieving significant framerate increases with little loss of visual detail.

As imagens são sinais que possuem muita informação. Os objetos representados em ima- gens podem sofrer deformações fazendo com que suas características mudem, o que difi- culta o reconhecimento do objeto. A chave para o sucesso de um sistema de reconheci- mento de padrões em imagens é escolher adequadamente a sua abordagem e um modelo para as feições presentes nas imagens. Uma das dificuldades é extrair e selecionar as feições que são mais discriminantes entre as diferentes classes usadas para modelar um objeto. Os modelos ativos de formas (Active Shape Models ASM) adaptam-se às defor- mações de um objeto. O objeto a ser modelado, pode ser representado com um modelo de pontos distribuídos (Point Distribution Models PDM). O PDM consiste de pontos de interesse ou marcadores, que permitem a extração de feições em localizações específicas do objeto. Após tratar a incerteza da localização e oclusão dos marcadores é possível ex- trair as feições mais representativas, obtendo-se um desempenho alto em termos da taxa de reconhecimento. Nesta tese são introduzidas novas formas para extrair e selecionar feições com modelos ativos de formas, que melhoram a taxa de classificação onde há objetos deformáveis. Esta tese é inovadora no sentido de aperfeiçoar o uso de ASMs na classificação de faces humanas, e na sua aplicação no monitoramento visual de outros tipos de objetos deformáveis. / Images are signals that have a lot of information. The objects depicted in images may suf- fer deformations causing changes in their characteristics, which hinders the recognition of the object. The key to the success of a system of pattern recognition in images is to choose properly your approach and a model for the features in the images. One difficulty is to extract and select the features that are most discriminating between different classes used to model an object. The Active Shape Models (ASM) adapt to deformations of an object. The object to be modeled can be represented with a Points Distribution Model (PDM). The PDM consists of points of interest or landmarks that allow the extraction of features in specific locations of the object. After treating the uncertainty of the location and occlu- sion of the landmarks it is possible to extract the most representative features, obtaining a high performance in terms of recognition rate. This thesis introduces new ways to extract and select features with ASMs, which improve the classification rate where deformable objects are present. This thesis is innovative in the sense that improves the use of ASMs in the classification of human faces, and that can be applied in visual monitoring of other types of deformable objects.

A pele possui um grande número de mecanismos de defesa antioxidante. No entanto, a exposição prolongada à radiação ultravioleta (RUV), é capaz de aumentar a concentração de espécies reativas de oxigênio (EROs) provocando um desequilíbrio antioxidante/oxidante. A geração de EROs pode levar ao fotoenvelhecimento e doenças, como o câncer. A administração tópica de antioxidantes é uma maneira eficiente de enriquecer o sistema protetor cutâneo endógeno e, assim, uma estratégia para reduzir os danos oxidativos causados pela RUV à pele. Entretanto, para fornecer a proteção adequada à pele, estas substâncias devem ultrapassar a barreira imposta pelo estrato córneo. O extrato de Lychnophora salicifolia Mart. possui compostos com atividades antioxidante, anti-inflamatória e analgésica, como o ácido clorogênico e a vicenina-2, sendo, portanto, um possível candidato à agente protetor dos danos induzidos pela radiação na pele. Assim, o objetivo do presente trabalho foi avaliar o potencial fotoquimiopreventivo deste extrato e do ácido clorogênico, bem como de formulações contendo o extrato e a substância isolada encapsulados em lipossomas. Para atingir tal objetivo, foram realizados experimentos in vitro e in vivo de atividade antioxidante e eficácia fotoquimiopreventiva para comprovação do potencial antioxidante e anti-inflamatório, estudos de liberação e estudos de penetração cutânea das formulações utilizando pele humana e pele de orelha de porco. Os resultados obtidos demonstraram que o extrato possui atividade antioxidante in vitro e baixa citotoxicidade. A incorporação do extrato e da substância isolada em lipossomas foi bem sucedida, uma vez que estes demonstraram uma boa estabilidade físico-química e aumentaram a penetração dos compostos na pele de camundongos sem pelos. As formulações contendo lipossomas permitiram que os compostos do extrato e o ácido clorogênico isolado atravessassem o estrato córneo chegando até epiderme e derme na pele humana ex vivo. O acúmulo de partículas nos folículos pilosos parece não exercer influencia neste processo. Os extrato foi capaz de sequestrar EROs intracelulares e evitar a depleção do antioxidante endógeno GSH tanto em cultura de células como nos experimentos in vivo. Também foi observada a inibição in vivo da metaloproteinase de matriz-9 (MMP-9), enzima ativada pela RUV e que tem a capacidade de degradar os componentes da matriz extracelular da pele. Além disso, o extrato apresentou atividade anti-inflamatória superior à do ácido clorogênico, verificada pela diminuição dos níveis de citocinas pró-inflamatórias (IL-1?, IL-6 e TNF-?) e da atividade da enzima mieloperoxidase (MPO) in vivo. Portanto, o extrato parece ser um agente fotoquimiopreventivo promissor para uso tópico e, as formulações desenvolvidas, um sistema viável para liberação destas substâncias na pele. / The skin has several defense mechanisms to avoid oxidant damages. However, a prolonged exposition under ultraviolet radiation (UVR) may increase reactive oxygen species (ROS) concentration causing antioxidant/oxidant imbalance. ROS generation can induce photoaging and skin cancer. Topical administration of antioxidants is an efficient way to fortify the endogenous protection system and to reduce the oxidative damage caused by UVR. Nevertheless, to be effective, these compounds need to pass through the skin barrier imposed by stratum corneum. Lychnophora salicifolia Mart. extract has antioxidant, antiinflammatory and analgesic compounds, such as chlorogenic acid and vicenin-2, and it may be a skin protector agent against UVR damage. Therefore, the aim of this study was to evaluate the photochemopreventive potential of this extract and chlorogenic acid, as well as their formulation containing liposomes. In vitro and in vivo tests were performed to prove antioxidant and antiinflammatory activity. Formulation release and skin penetration studies were also carried out in human and porcine ear skin. The results showed that the extract has antioxidant activity in vitro and low cytotoxicity. The extract and the isolated compound were successfully entrapped in liposomes, demonstrating a good physic and chemical stability and increasing the skin penetration in hairless mice. The formulations containing liposomes allowed that the extract compounds and chlorogenic acid passed through the stratum corneum and reached epidermis and dermis in human skin ex vivo. The hair follicle uptake of the particles do not influenced the penetration process. The extract was able to scavenge intracellular ROS and avoid the depletion of the endogenous GSH both in cell culture and in vivo, even as it inhibited matrix metalloproteinase 9 (MMP-9), enzyme activated by UVR that degrades skin matrix extracellular components. The extract also presented larger antiinflammatory properties than chlorogenic acid, decreasing the cytokines (IL-1?, IL-6 and TNF-?) levels and the mieloperoxidase activity in vivo. Therefore, the results suggest the potential applicability of the extract as a photochemopreventive agent to topical use and the developed formulations seem to be a viable system to release these compounds to the skin.

Radiologists are often plagued by limited time for completing their work, with an ever increasing workload. A picture archiving and communication system (PACS) is a platform for daily image reviewing that improves their work environment, and on that platform for example spinal MR images can be reviewed. When reviewing spinal images a radiologist wants vertebrae labels, and in Sectra's PACS platform there is a good opportunity for implementing an automatic method for spinal labeling. In this thesis a method for performing automatic spinal labeling, called a vertebrae classifier, is presented. This method should remove the need for radiologists to perform manual spine labeling, and could be implemented in Sectra's PACS software to improve radiologists overall work experience.Spine labeling is the process of marking vertebrae centres with a name on a spinal image. The method proposed in this thesis for performing that process was developed using a machine learning approach for vertebrae detection in sagittal MR images. The developed classifier works for both the lumbar and the cervical spine, but it is optimized for the lumbar spine. During the development three different methods for the purpose of vertebrae detection were evaluated. Detection is done on multiple sagittal slices. The output from the detection is then labeled using a pictorial structure based algorithm which uses a trained model of the spine to correctly assess correct labeling. The suggested method achieves 99.6% recall and 99.9% precision for the lumbar spine. The cervical spine achieves slightly worse performance, with 98.1% for both recall and precision. This result was achieved by training the proposed method on 43 images and validated with 89 images for the lumbar spine. The cervical spine was validated using 26 images. These results are promising, especially for the lumbar spine. However, further evaluation is needed to test the method in a clinical setting. / Radiologer får bara mindre och mindre tid för att utföra sina arbetsuppgifter, då arbetsbördan bara blir större. Ett picture archiving and communication system (PACS) är en platform där radiologer kan undersöka medicinska bilder, däribland magnetic resonance (MR) bilder av ryggraden. När radiologerna tittar på dessa bilder av ryggraden vill de att kotorna ska vara markerade med sina namn, och i Sectra's PACS platform finns det en bra möjlighet för att implementera en automatisk metod för att namnge ryggradens kotor på bilden. I detta examensarbete presenteras en metod för att automatiskt markera alla kotorna utifrån saggitala MR bilder. Denna metod kan göra så att radiologer inte längre behöver manuellt markera kotor, och den skulle kunna implementeras i Sectra's PACS för att förbättra radiologernas arbetsmiljö. Det som menas med att markera kotor är att man ger mitten av alla kotor ett namn utifrån en MR bild på ryggraden. Metoden som presenteras i detta arbete kan utföra detta med hjälp av ett "machine learning" arbetssätt. Metoden fungerar både för övre och nedre delen av ryggraden, men den är optimerad för den nedre delen. Under utvecklingsfasen var tre olika metoder för att detektera kotor evaluerade. Resultatet från detektionen är sedan använt för att namnge alla kotor med hjälp av en algoritm baserad på pictorial structures, som använder en tränad model för att kunna evaluera vad som bör anses vara korrekt namngivning. Metoden uppnår 99.6% recall och 99.9% precision för nedre ryggraden. För övre ryggraden uppnås något sämre resultat, med 98.1% vad gäller både recall och precision. Detta resultat uppnådes då metoden tränades på 43 bilder och validerades på 89 bilder för nedre ryggraden. För övre ryggraden användes 26 stycken bilder. Resultaten är lovande, speciellt för den nedre delen. Dock måste ytterligare utvärdering göras för metoden i en klinisk miljö.

Les roulements à billes sont l’un des composants les plus importants et les plus critiques dans les turbomachines ou dans les éoliennes. Les butées à billes rencontrées dans les pieds de pales d’éoliennes doivent supporter des chargements très élevés, avec des bagues très fines par rapport aux dimensions du palier. Le roulement à quatre points de contact à haute vitesse est un autre exemple de bagues minces, où la cinématique interne est fortement liée à la géométrie des pistes qui elle, dépend de la rigidité des bagues et des logements. Pour cette application, les pistes intérieures et extérieures sont archées et bien souvent constituées de deux demi-bagues. La souplesse de ces dernières ainsi que celle du logement modifie la géométrie interne et l’interaction entre les composants. Il est proposé dans cette thèse un modèle permettant de dimensionner des roulements à billes à quatre points de contact, principalement dans le domaine d'application des turbines aéronautiques. Ce modèle est capable de rendre compte des déformations globales des bagues et de leur logement et environnement proche. Un ensemble de travaux existants et différentes possibilités envisagées pour la mise en place d’un modèle de roulement à bagues déformables est présenté pour définir une stratégie de couplage efficace entre un modèle analytique et un modèle éléments finis. La prise en compte de la souplesse des bagues s’appuie sur la résolution préalable d’un problème semi analytique de modélisation avec bagues rigides. Ensuite un couplage entre les résultats de ce modèle et un modèle éléments finis est réalisée pour prendre en compte la souplesse des bagues. Des choix sont nécessaires pour ce couplage, notamment sur la modélisation des contacts billes/bagues par l’utilisation de forces nodales pour simuler fidèlement ces contacts. Plusieurs méthodes sont ainsi évaluées pour calculer au mieux la nouvelle géométrie de la bague, en observant son comportement lorsqu'elle est soumise au contact d'une bille. Finalement, cette souplesse est intégrée au modèle semi analytique pour comparer le comportement d'un roulement à bagues rigides à celui d'un roulement à bagues souples. Des premiers résultats numériques sur une géométrie académique montrent des variations des grandeurs internes du roulement (angles de contact, ellipse de contact) ainsi qu’une meilleure répartition du chargement. Des essais ont été réalisés pour valider expérimentalement le modèle développé dans cette thèse. Les comparaisons par mesures du déplacement axial des bagues et des ondulations en surface des bagues montrent que la souplesse du support n’est pas négligeable, même dans le cas de bagues larges. Egalement, ces essais ont démontré la pertinence du couplage entre un modèle analytique et un modèle éléments finis pour rendre compte des déformations de bagues de roulements à billes à quatre points de contact. / Ball bearings are one of the most important and most critical part in turbomachine and wind turbine. They require a careful design in order to create reliability and economic relevance, which leads to compact bearings with high dynamic and static load capacity. Then ball bearing encountered in wind turbine must carry high loads, with thin rings regarding mean diameter of the bearing. High speed four point contact ball bearing is another example of thin rings, where internal kinematics is highly linked to raceway geometry, and raceway geometry depends on rings and housing stiffness. For this application, internal and external ring are arched and frequently made of two parts. There stiffness change the internal geometry and interaction with bearings components. It implies a change in load distribution and internal speed. As a consequence bearing and housing stiffness is an important parameter in order to estimate the admissible loads for the bearing. This thesis propose a model for the four point contact ball bearing, mainly for aeronautical turbine engine. This model can account for structural ring deformation as well as of housing deformation. Some existing work and different possibility for such a model are presented in order to define a coupling strategy between an analytical model and a finite element model. The accounting for ring stiffness rely on the resolution of a rigid ring semi analytical model. Then a coupling between this results and finite element results is done in order to account for ring stiffness. Some choices are made for the coupling, especially on ball/ring interaction by using nodal forces to model contact with fidelity. Some methods are evaluated to compute new ring geometry due to contacts with balls. Finally this stiffness is integrated in the semi analytical model in order to compare the behavior of rigid ring bearing with deformable ring bearing. First numerical results on an academic bearing shows change in internal parameter (contact angle, contact ellipse) and a better load distribution. Some experimental tests are made in order to validate the model presented in this thesis. Comparison on axial displacement and ring surface undulation shows that housing stiffness is not negligible even with large ring bearing. This tests show the relevance of a coupling between an analytical model and a finite element model in order to account for ring deformation in four point contact ball bearing.

Cartographier la connectivité fonctionnelle du cerveau à partir des donnés d'IRMf est devenu un champ de recherche très actif. Cependant, les outils théoriques et pratiques sont limités et plusieurs tâches importantes, telles que la définition empirique de réseaux de connexion cérébrale, restent difficiles en l’absence d'un cadre pour la modélisation statistique de ces réseaux. Nous proposons de développer au niveau des populations, des modèles joints de connectivité anatomique et fonctionnelle et l'alignement inter-sujets des structures du cerveau. Grâce à une telle contribution, nous allons développer des nouvelles procédures d'inférence statistique afin de mieux comparer la connectivité fonctionnelle entre différents sujets en présence du bruit (bruit scanner, bruit physiologique, etc.). / Mapping the functions of the human brain using fMRI data has become a very active field of research. However, the available theoretical and practical tools are limited and many important tasks like the empirical definition of functional brain networks, are difficult to implement due to lack of a framework for statistical modelling of such networks. We propose to develop at the population level, models that jointly perform estimation of functional connectivity and alignment the brain data across the different individuals / subjects in the population. Building upon such a contribution, we will develop new methods for statistical inference to help compare functional connectivity across different individuals in the presence of noise (scanner noise, physiological noise, etc.).

This master’s thesis deals with kidney segmentation in perfusion magnetic resonance image sequences. Kidney segmentation is carry out by a few methods such as regionbased techniques, deformable models, specimen-based methods, edge-oriented methods etc. The universal algorithm for patient kidney segmentation still does not exist. Proposed method is an active contour Snake, which is created in programming environment MatLab. Final contours are quantitatively and visually compared to manual kidney segmentation.

Cette thèse vise à investiguer des moyens d'optimiser les performances de l'imagerie à haut contraste dans l'optique et le proche infrarouge pour la détection d'exo-planètes. L'étude principale a été menée sur le contraste à faible séparation permettant l'imagerie d'exo-planètes dans leur zone habitable. Cette détection directe est rendue possible par le développement des futurs grands télescopes et de coronographes de plus en plus performants à faible séparation. L'approche retenue permet de créer une zone sombre à haut contraste grâce à la coronographie et au « wavefront shaping » (contrôle de l'amplitude et de la phase avec 2 miroirs déformables), mais qui est limité par les effets de propagation de Fresnel. Les résultats obtenus ont déterminé les limitations de configuration optique pour le « wavefront shaping ». Grâce à une approche semi-analytique soutenue par des simulations numériques et une approche Monte-Carlo, ces limitations ont été analysées et quantifiées pour extraire les configurations optimales. Les résultats ont été appliqués au banc SPEED dont l'objectif est d'optimiser et de tester le haut contraste à faible séparation. Une deuxième étude a été une contribution à une étude générale de stabilité, en traitant la stabilité temporelle comme un paramètre indispensable dans la conception en amont d'instrument haut contraste. Un travail préliminaire a été initié sur la stabilité des instruments de mesure eux-mêmes à travers l'étude thermique d'un système de métrologie. Enfin, un dernier volet a été une étude de simulation de performances d'un nouveau concept d'imagerie différentielle basé sur l'acquisition d'images réalisées avec différentes tailles de pupilles. / This thesis aims to optimize high-contrast imaging performance in visible and near infrared for exoplanet detection. The main study focuses on high-contrast at small separation, to image exoplanets in their habitable zone. This direct detection is achievable with the next Extremely Large Telescopes and with the development of coronagraph providing high performance at small separation. The approach adopted for this study creates a high-contrast region (a dark hole) with the combination of coronagraphy and wavefront shaping (wavefront control of both phase and amplitude with 2 deformable mirrors) but is limited by the Fresnel propagation of phase aberrations. The goal of this work is to define the wavefront shaping limitation in optical configuration (deformable mirrors location, component optical quality, beam diameter). A semi-analytic approach followed by a Monte-Carlo analysis of numerical end-to-end simulations is studied, resulting in the definition of the optimal configuration. Results are then applied to SPEED, a test bench to optimize and test high-contrast imaging at small separation with a segmented pupil. Another aspect of this thesis is a contribution to a stability study to treat the temporal stability as a crucial parameter in high-contrast imaging instrumentation, at the conception level. A preliminary work is initiated during the thesis to analyse the stability of the measuring instrument itself. A metrology tool and its thermal behaviour are thus studied. Finally, the last part of this thesis is a performance analysis of a new differential imaging technique, developed to improve high contrast with observations with different diaphragm sizes.

Indiana University-Purdue University Indianapolis (IUPUI) / An algorithm was developed in to efficiently segment the inner-limiting membrane (ILM) and retinal pigmented epithelium (RPE) from spectral domain-optical coherence tomography image volumes. A deformable model framework is described and implemented in which free-form deformations (FFD) are used to direct two deformable sheets to the two high-contrast layers of interest. Improved accuracy in determining retinal thickness (the distance between the ILM and the RPE) is demonstrated against the commercial state-of-the-art Spectralis OCT native segmentation software. A novel adaptation of the highest confidence first (HCF) algorithm is utilized to improve upon the initial results. The proposed adaptation of HCF provides distance-based clique potentials and an efficient solution to layer-based segmentation, reducing a 3D problem to 2D inference.

In this study, the characteristics of the flow around a paraglider wing were investigated through the use of Computational Fluid Dynamics (CFD) simulations by solving both Reynolds Averaged Navier-Stokes equations and Delayed Detached Eddy Simulations were employed. This allowed the observation of how the unique shape of the canopy of a paraglider can influence the behaviour of the flow and how aerodynamic hysteresis can manifest on this sort of wing. Furthermore, the interaction between the highly deformable structure of the paraglider and the flow was examined through a two-way, loosely coupled Fluid-Structure Interaction (FSI) analysis. The methodology for the FSI analysis was first validated by employing a simplified model of the canopy before the full paraglider wing was analysed. Two different structural meshes were tested, using membrane elements or shell elements, respectively. The membrane element mesh prompted a collapse of the structure, while the mesh presenting shell elements allowed for a successful completion of the analysis.