This paper is concerned with mesh refinement techniques for treating elliptic boundary value problems in domains with re- entrant edges and corners, and focuses on numerical experiments. After a section about the model problem and discretization strategies, their realization in the experimental code FEMPS3D is described. For two representative examples the numerically determined error norms are recorded, and various mesh refinement strategies are compared.

Fotorealistiska 3d-bilder används idag inom ett brett spektrum av branscher. Framställningen av denna typ av grafik kräver ofta väldigt mycket datorkraft. Vid rendering med renderingsmotorer som använder sig av raytracing algoritmer är aliasing ett medfött problem. Lösningen heter anti-aliasing som arbetar för att undvika aliasing artefakter som jagged edges eller Moiré-effekter med mera. En del av anti-aliasingprocessen är supersampling som ofta kräver mycket datorkraft. Att optimera parametrar för supersampling är därför mycket viktigt. Det är möjligt att genom optimering spara väldigt mycket datorkraft och därmed tid. Detta arbete innehåller resultat från experiment där deltagare får bedöma bilder med olika kvalité av anti-aliasing. Resultaten av dessa experiment kan användas som referens vid optimering av renderingsparametrar för anti-aliasing vid rendering med hjälp av Mental Ray.

Le champ de force CLAYFF est largement employé pour modéliser les interfaces de minéraux argileux – et minéraux apparentés – avec une phase aqueuse. Dans les simulations, les particules d’argile sont typiquement représentées par des feuillets semi-infinis, ainsi seules les surfaces parallèles au plan du feuillet (surfaces basales) sont considérées. Cette simplification est valable dans la mesure où ces surfaces sont majoritaires, mais les feuillets d’argile sont en réalité de taille nanométrique et terminés par des surfaces latérales, ou bordures. Ces surfaces peuvent non seulement adsorber les espèces en solution mais sont aussi sujettes aux transferts de proton, et tous les processus physico-chimiques liés à l’acidité de la phase aqueuse se produisent de façon prédominante au niveau des bordures. En ajoutant au champ de force CLAYFF un terme angulaire métal-O‑H dont les paramètres ont été correctement ajustés, les simulations réalistes des interfaces de bordure deviennent possibles.Les paramètres des termes Al-O‑H et Mg-O‑H ont été obtenus à partir de calculs DFT sur des modèles structuraux du bulk, de la surface basale et de la bordure de la gibbsite Al(OH)3 et de la brucite Mg(OH)2, dont les feuillets peuvent être considérés comme le squelette des minéraux argileux et apparentés. De plus, le terme Si-O‑H a été paramétré à partir d’un modèle de bordure de la kaolinite Al2Si2O5(OH)4. Les propriétés structurales et dynamiques issues de simulations de dynamique moléculaire DFT et classiques basées sur CLAYFF avec et sans terme métal-O‑H ont été comparées. Le champ de force modifié améliore nettement la description des surfaces hydroxylées : l'orientation et la dynamique librationnelle des groupes hydroxyles, les liaisons hydrogène dans lesquelles ils sont impliqués, et la coordination des atomes de métal appartenant aux bordures sont tous plus proches de la réalité. / The CLAYFF force field is widely used to model the interfaces of clay minerals – and related layered materials – with an aqueous phase. In the simulations, clay particles are typically represented by semi-infinite layers, i.e. only surfaces parallel to the layer plane (basal surfaces) are considered. This simplification is acceptable to a certain extent, but clay layers are really nanosized and terminated by lateral surfaces or edges. These surfaces can not only adsorb solvated species but are also subject to proton transfers, and all physico-chemical processes related to the aqueous phase acidity predominantly occur at the edges. By adding to the CLAYFF force field a Metal-O‑H angle bending term whose parameters are correctly adjusted, the simulations of edge interfaces become possible.The parameters of Al-O‑H and Mg-O‑H terms were obtained from DFT calculations on bulk, basal surface and edge structural models of gibbsite Al(OH)3 and brucite Mg(OH)2, whose layers can be considered as the backbones of clay minerals and related materials. In addition, the Si-O‑H term was parametrized from an edge model of kaolinite Al2Si2O5(OH)4 . Molecular dynamics simulations based on DFT and on CLAYFF with and without Metal-O‑H term were performed. The modified force field clearly improves the description of hydroxylated surfaces : the orientation and the librational dynamics of the hydroxyl groups, the hydrogen bonding, and the coordination of metal atoms belonging to the edge are all closer to reality.

Cette thèse s’inscrit dans le cadre de l’analyse des besoins de personnes malvoyantes dans le but de développer de nouvelles solutions d’assistance visuelle en utilisant le principe de réalité augmentée. Le principal objectif de ces travaux était le développement d’un dispositif d’assistance visuelle pour faciliter la mobilité de personnes malvoyantes grâce à un algorithme qui en temps réel adapte sa réponse en fonction des besoins de l’utilisateur et de la situation dans laquelle il évolue. Le premier postulat de cette thèse est d’utiliser l’acuité résiduelle fonctionnelle des malvoyants afin de leur permettre de percevoir un certain nombre d’informations. Le second postulat est d’utiliser les seules informations pertinentes, utiles à un malvoyant, afin d’améliorer sa perception du monde dans lequel il évolue. Le premier axe de recherche a consisté à analyser les besoins des malvoyants afin de recenser, les indices visuels utiles à rehausser afin d’améliorer la perception des malvoyants. Cette étude a été réalisée en immersion et une enquête précise a été menée auprès de malvoyants. Cette étude permet de mieux comprendre les besoins des malvoyants, les méthodes qu’ils utilisent ainsi que leurs usages des dispositifs actuels. Le deuxième axe de recherche a consisté à concevoir et à mettre en oeuvre un algorithme de traitement d’images répondant aux besoins identifiés. Un outil interactif a été développé qui permet de sélectionner la quantité de contours en fonction de la situation. Ce détecteur de contour optimise sa détection afin d’obtenir des contours plus exploitables pour les malvoyants, comparés aux résultats des autres méthodes de l’état de l’art. Cet outil a été testé et validé auprès d’une population donnée de personnes malvoyantes. Ces tests réalisés sur écran ont démontré que les contours constituent des indices visuels très importants qui peuvent être d’une grande aide dans l’analyse d’une scène. Le troisième axe de travail a consisté au développement d’un système de réalité augmentée permettant d’utiliser ce détecteur de contours dans un contexte de mobilité. L’analyse des besoins des malvoyants vis-à-vis d’un tel dispositif nous a permis de définir les caractéristiques indispensables pour le système de calcul, la caméra et le dispositif d’affichage. Concernant le système d’affichage, l’analyse des besoins des malvoyants en termes de profil, de couleur, de largeur des contours, nous a permis de définir les paramètres nécessaires pour un affichage qui répond à ces besoins. Il a également été pris en compte dans les développements les paramètres physiologiques de chaque observateur afin que les images affichées soient visuellement confortables / This thesis was done in the context of visual impaired needs analysis with the goal of new augmented reality visual assistance device development. The main goal of this work was the development of assistive device for mobility of visual impaired people by the use real-time image processing algorithm which take into account user needs and the context. The first postulate is the use of residual visual acuity of visual impaired people to allow them to see more information. The second postulate is the use only most useful information for visual impaired people for the understanding of the situation where are they. The first research axis was an analysis of needs of visual impaired to identify visual cues, which one we need to enhance to help them. To do this, I have done an immersive stage into a re-adaptation clinic for visually impaired. I have also done a questionnaire to identify and understand how current products answers partially to their needs. The second research axis was the development of a new image processing to answer identified needs. I have developed an interactive tools that allow the user to select the amount of edges for each situation, context. This detector optimizes its result to provide better results than others state of the art evaluated methods. This tool was evaluated and validated during visual test by visual impaired people. We have demonstrated that edges are one of the most important visual cues for visual impaired people to analyze a scene. The third research axis was the development of the augmented reality system to use my tool in a context of mobility. To do this, I have analyzed the needs of visual impaired people for this type of devices. I have also defined main requirements of the desired device for the processing unit, the camera and the display module. For display module, I have analyzed physiologic needs of visually impaired, in terms of profile, colors, and thickness to answer their needs. I have also developed an image generation model which takes into account many physiologic parameters of each observer to create visually comfortable images

Des assemblages de pollinisateurs sauvages plus diversifiés et abondants fourniraient un service de pollinisation plus stable et efficace pour une plus large gamme de cultures. La rupture de l’équilibre entre milieux semi-naturels et anthropisés dans la mosaïque paysagère est souvent invoquée pour expliquer le déclin des pollinisateurs. Le maintien des abeilles sauvages est fortement dépendant de la disponibilité, dans le rayon de dispersion de l’espèce, des ressources floristiques et des micro-habitats de nidification et d’hivernage. Nous avons analysé dans une synthèse bibliographique l'effet de la proximité à la forêt ou de la proportion de forêt dans le paysage sur deux services (pollinisation et contrôle des ravageurs) et un dis-service écosystémiques (ravageurs) rendus par les arthropodes aux cultures. Nos propres travaux fournissent les premiers exemples approfondis en milieu tempéré de l’intérêt des lisières forestières pour les abeilles pollinisatrices des cultures. A l’échelle de parcelles de colza et de pommiers, nous avons démontré que les lisières forestières (i) sont le site de nidification/accouplement de nombreuses espèces printanières, (ii) offrent dès le début du printemps une diversité de ressources florales favorables, et (iii) ont un intérêt variable dans la saison en fonction des groupes écologiques d’abeilles. La diversité des abeilles sauvages régresse à l’intérieur du champ avec la distance à la lisière, en fonction des capacités de vol. A la lumière de nos résultats, nous suggérons un aménagement agro-écologique des territoires agricoles intégrant des lisières forestières dans une trame arborée favorable aux abeilles. / More diverse and abundant assemblages of wild pollinators should provide a more stable and effective pollination service for a wider range of crops. The disruption of the balance between semi-natural and manmade environments in the mosaic landscape is often invoked to explain the decline of pollinators. The survival of wild bees is highly dependent on the availability, within species dispersal radius, of both floral resources and nesting and wintering micro-habitats. In a literature review, we analyzed the effect of proximity to the forest or the proportion of forest in the landscape on both ecosystem services (pollination and pest control) and dis-services (pests) provided by arthropods to crops. Our own work provides the first in-depth demonstration of the interest of forest edges for bees pollinating crops in temperate regions. At the scale of oilseed and apple crops, we demonstrated that forest edges (i) are the nesting / mating sites for many spring species, (ii) provide a diversity of favorable floral resources at early spring, and (iii) have a season-dependent interest for bee guilds. The diversity of wild bees decreases within the field with distance from the edge, depending on the bee flight abilities. In light of our results, we suggest an agro-ecological management of agricultural land incorporating forest edges in a woody network in favour of wild bees.

The diploma thesis deals with the construction design of rail mounted transfer cars. The first of the designed cars is equipped with the electrical drive and the second is non-driven and must be towed or pushed. This thesis contains description of main components of the transfer cars and their implementation. The next section deals with original construction design of the transfer cars. The thesis includes functional calculation of travel wheels, the design and check of the travel unit and the strength calculation of the connecting pin. Conclusion of the thesis deals with the strength analysis of the transfer car frame using the finite element method. The required technical drawings are attached to the thesis.

Stockholm is an archipelago of islands connected by water that historically has been an important resource for the city and for the industries, which found an easy access for ships and therefore they settled on strategic positions along the edges. This thesis investigates the topics of water, industrial heritage and edges in the city of Stockholm: these aspects are strong in their individual identity but they also interact in a powerful and interesting way. This work intervenes where this pattern is still visible -due to the presence of water and industries- but not accessible because it lacks the third element of connection with the city. The aim is therefore to investigate strategies that increase and reconnect the potential of these aspects that got disconnected through time. To obtain accessibility and usability, the edge was transformed and redefined to enhance the experience of walking along it. An analysis was carried out and a proposal was designed for the site of Lövholmen, which has these characteristics -the water, a strong industrial heritage and proximity to the city- that are now disconnected. The opening of the edge and possibilities of walking will transform and reconnect the site - and the richness in it- with the city of Stockholm.

This study addresses the critical need for effective thermal management in hypersonic vehicles facing intense heat at their leading edge due to high enthalpy flow. The objective is to propose an active impingement cooling system that ensures the structural stability and performance of these vehicles. This dissertation presents an in-depth exploration of the numerical simulations conducted on the hypersonic leading edge, focusing on a 3mm radius with active cooling utilizing supercritical carbon dioxide (sCO2) as the coolant. The research incorporates conjugate simulations that merge external hypersonic flow and sCO2 active cooling. Utilizing a thermodynamic non-equilibrium two-temperature model and various chemical models, including the 5-species Park's model and the 11-species Gupta's model, separate validations for the external hypersonic flow and internal sCO2 coolant flow were conducted. These validations facilitated combined simulations, underscoring the potential of maintaining metal temperatures within operational limits using sCO2 coolant. A comparative study of the 5- 5-species Park model and 11-species Gupta model demonstrated the former's effectiveness in predicting flow fields at Mach 7. Furthermore, this study shows the effect of varying the coolant tube-to-leading-edge distance (H/D), Thermal barrier coating thickness, and impingement angles, demonstrating improved heat transfer performance through these variations. A key aspect of this work is the exploration of converting hypersonic vehicle heat flux to power using the sCO2 cycle. The conceptual study, illustrated through the Mach 7 case, confirms the feasibility of harnessing power from aerodynamic heat flux, marking a significant progression in the field. This research contributes to the field by offering a detailed analysis of active impingement cooling for hypersonic leading edges, integrating real gas effects and multiple chemical models. The study adds novelty by investigating heat transfer enhancements through iv geometric variations and evaluating sCO2's potential as a coolant, addressing key facets of hypersonic vehicle thermal management.

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Made available in DSpace on 2014-07-29T16:21:22Z (GMT). No. of bitstreams: 1 Dissertacao Maria Adriana Santos Carvalho.pdf: 7393945 bytes, checksum: 29cd7cf3741dce0d99bae27e39b430e4 (MD5) Previous issue date: 2009-02-24 / Microclimatic changes enhanced by the proliferation of edges in fragmented landscapes, known as "edge effects" may result on shifts in species composition, structure of communities and ecological processes. Despite the dramatic increase in edge areas caused by anthropogenic habitat fragmentation, the edges and their areas of influence is a relevant structural feature also in the natural landscape. This is evident in the Cerrado biome, which is suffering an accelerated degradation and habitat loss and is composed of mosaics of vegetation types which are common boundaries or ecotones. The bryophytes are an ideal group for assess the edge effects because are vulnerable to microclimatic changes promoted by their physiological conditions, making them particularly useful as indicators of the adverse fragmentation effects. Thus, this study aimed to assess how the communities of epiphytes mosses (Bryophyta) respond to forest edges originated of anthropogenic fragmentation and the natural edges in the grassland-forest transitions in the Cerrado. The study areas are located in the Parque Estadual da Serra de Caldas Novas and its surroundings, including municipalities of Caldas Novas and Rio Quente, state of Goiás. Sampling was done in three habitat types: (1) gallery forests on the slopes of the mountain with abrupt transitions to rock outcrops fields, (2) edge (0 to 10 m) and (3) interior (100 to 110 m) of seasonal forest fragments surrounded by a matrix of grazing. These were the three treatments considered in the analysis, described by the abbreviations: BN (natural edge), BA (anthropogenic edge) and IF (interior of the fragment). For each treatment four replicates were selected. Four plots (10´10m) were randomly delimited along transects (10´200m) for each treatment in each area. For the sampling of mosses in the plots, were selected all trees with perimeter at breast height (PBH) &#8805; 20 cm and with minimum bryophytes coverage of 300cm2. For the quantitative survey of mosses was employed the interception line method. The comparison of Jackknife richness estimates (33.56 to IF, 30.56 to BA and 25.63 to BN) showed that there were differences between IF and BN. The coverage of mosses was significantly higher in BN than in BA (F2,45 = 5.34, p = 0.008). The analysis of similarities (ANOSIM) showed that the community of mosses was more distinct in BN, and the composition of species in this environment was significantly dissimilar to BA in IF (R = 0.198, p < 0001). Two factors may explain the fact that the edge effect on species richness and coverage of epiphytic mosses has not been shown in this study: (1) The homogeneity of the vegetation structure observed between edge and interior and (2) the fact that the study had considered only the mosses, 8 whereas many studies confirm a higher sensitivity to disturbance of the liverworts. Clearer effects were observed between BA and BN, both in coverage and in species composition, which is probably due to differences in spatial and temporal development of these edges, or topographic features of the gallery forests, particularly the fact of being located in depressions with creeks, which probably provides more moisture in these environments. The chi-square test showed significant differences in the frequency of occurrence of life forms in the different treatments, except for the tuft form. The greatest value of chi-square occurred to the flabelliform life form, which predominated in BN, collaborating with the evidence already presented of microclimatic conditions more favorable to mosses in BN, since the flabelliform habit are intolerant to desiccation. This indicates that the use of functional groups of bryophytes, such as life forms can generate more generalization and get clearer answers than species richness in the evaluation of the edge effects. / As mudanças microclimáticas promovidas pela proliferação de bordas nas paisagens fragmentadas, designadas efeitos de borda , podem resultar em alterações na composição de espécies, estrutura das comunidades e processos ecológicos. Apesar do drástico aumento das áreas de borda causadas pela fragmentação antrópica, as bordas e suas áreas de influência constituem uma importante característica estrutural também nas paisagens naturais. Isto é evidente no bioma Cerrado, que além da acelerada perda e degradação de habitats que vem sofrendo, é também composto por mosaicos de tipos vegetacionais cujos limites ou ecótonos são comuns. As briófitas constituem um grupo de organismos ideal para a avaliação dos efeitos de borda, pois devido às suas condições fisiológicas elas são vulneráveis às alterações microclimáticas, o que as torna particularmente úteis como indicadoras dos efeitos adversos da fragmentação. Diante disso, este trabalho teve por objetivo avaliar como as comunidades de musgos (Bryophyta) epífitos respondem às bordas florestais proporcionadas antropicamente e às bordas naturais nas transições campo-floresta no Cerrado. As áreas de estudo estão localizadas no Parque Estadual da Serra de Caldas Novas e no seu entorno, compreendendo os municípios de Caldas Novas e Rio Quente, estado de Goiás. A amostragem foi feita em três tipos de habitats: (1) florestas de galeria nas encostas da serra com transições abruptas para campos rupestres; (2) borda (0 a 10 metros) e (3) interior (100 a 110 metros) de fragmentos de florestas estacionais circundados por matriz de pastagem. Estes foram os três tratamentos considerados na análise, designados pelas siglas: BN (borda natural), BA (borda antrópica) e IF (interior do fragmento). Para cada tratamento foram selecionadas quatro réplicas. Quatro parcelas de 10´10m foram plotadas aleatoriamente ao longo de transectos de 10´200m para cada tratamento em cada área. Para a amostragem dos musgos nas parcelas, foram selecionadas todas as árvores com perímetro à altura do peito (PAP) &#8805; 20 cm e com cobertura mínima de briófitas de 300cm2. Para o levantamento quantitativo dos musgos foi adotado o método de interceptação de linha. A comparação das estimativas de riqueza de Jackknife (33,56 para IF, 30,56 para BA e 25,63 para BN) mostrou que houve diferenças apenas entre IF e BN e a cobertura de musgos foi significativamente maior em BN do que em BA (F2, 45 = 5,34; p = 0,008). A análise de similaridade (ANOSIM) mostrou que a comunidade de musgos foi mais distinta em BN, sendo que a composição de espécies neste ambiente foi significativamente dissimilar tanto de BA quanto de IF (R = 0,198; p < 0,001). Dois fatores podem explicar o fato do efeito de borda sobre a riqueza e 6 cobertura de espécies de musgos epífitos não ter sido evidenciado neste estudo: (1) A homogeneidade na estrutura da vegetação observada entre borda e interior e (2) o fato do estudo ter considerado apenas os musgos, enquanto muitos estudos confirmam uma maior sensibilidade das hepáticas aos diferentes distúrbios. Efeitos mais claros foram observados entre BA e BN, tanto na cobertura quanto na composição de espécies, o que se deve provavelmente às diferenças espaciais e temporais na criação destas bordas, ou ainda às características topográficas dos enclaves, principalmente o fato de estarem localizados em depressões e apresentarem cursos de água no seu interior, o que provavelmente determina maior umidade nestes ambientes. O teste de qui-quadrado mostrou diferenças significativas na freqüência de ocorrência das formas de vida nos diferentes tratamentos, exceto para a forma tufo. O maior valor de qui-quadrado ocorreu para a forma de vida flabeliforme, que predominou em BN, colaborando com as evidências já apresentadas de condições microclimáticas mais favoráveis aos musgos em BN, visto que o hábito flabeliforme é intolerante á dessecação. Isto indica que a utilização de grupos funcionais de briófitas, como formas de vida, pode gerar uma maior generalização e obter respostas mais claras que a riqueza de espécies na avaliação dos efeitos de borda.