Due to the fact that construction, maintenance and operation of buildings consume almost 50% of the energy today, architects play a major role in the reduction of energy consumption. The building’s envelope (façades and roof) can have a significant and measurable impact. With regard to overheating and the potential lost of internal heat, transparent parts of the building envelope have a large effect on the building’s energy consumption. Modern, transparent façade systems can fulfill contemporary demands, such as energy conservation, energy production or the degree of visual contact, of sustainable buildings in order to reduce internal heating, cooling, and electrical loads. An analysis of existing shading devices and façade design leads to a comparative analysis of conventional shading devices like horizontal and vertical blinds as well as eggcrate and honeycomb shading structures in a hot-humid climate like Austin, Texas. This study helped evaluating strengths and weaknesses of each device resulting in an optimization process of conventional shading devices. Ultimately, an optimized shading structure has been developed. This project aimed to develop an advanced transparent façade system for a south-oriented commercial façade in Austin, Texas, which fulfills high standards with regard to low energy use, by limiting cooling loads and demands for artificial lighting while avoiding glare and heat losses during the cold season. The optimization has been achieved in providing full shading for a specified period of time throughout the year while providing maximized solar exposure. The shading structure consists out of an array of fixed shading components varying in size and proportion to fulfill criteria like specific views, transparency and aesthetics. The shading structure has been compared to conventional shading devices and analyzed with regard to the reduction of annual solar radiation. The improvement in design and energy consumption contributes to the variety of shading structures for building skins. It is anticipated that the solutions will help to widen the options for aesthetically pleasing, high-performance façades for commercial buildings. / text

This dissertation examines the application of various classical root finding methods to digital maximum power point tracking (DMPPT). An overview of root finding methods such as the Newton Raphson Method (NRM), Secant Method (SM), Bisection Method (BSM), Regula Falsi Method (RFM) and a proposed Modified Regula Falsi Method (MRFM) applied to photovoltaic (PV) applications is presented. These methods are compared among themselves. Some of their features are also compared with other commonly used maximum power point (MPP) tracking methods. Issues found when implementing these root finding methods based on continuous variables in a digital domain are explored. Some of these discussed issues include numerical stability, digital implementation of differential operators, and quantization error. Convergence speed is also explored. The analysis is used to provide practical insights into the design of a DMPPT based on classical root finding algorithms. A new DMPPT based on a MRFM is proposed and used as the basis for the discussion. It is shown that this proposed method is faster than the other discussed methods that ensure convergence to the MPP. The discussion is approached from a practical perspective and also includes theoretical analysis to support the observations. Extensive simulation and experimental results with hardware prototypes verify the analysis. / text

The grape flavonoids include anthocyanins, tannins and flavonols, all of which contribute to grape and wine quality by influencing the colour and mouthfeel of red wine. These compounds are synthesized in different parts of the berry and during different stages of berry development. In addition, environmental and viticultural factors such as light exposure can also alter the flavonoid composition of grapes. An understanding of how synthesis of these compounds is coordinated, their relationship to wine quality and the influence of bunch light exposure on the flavonoid composition of grapes, could be used to improve fruit quality by enhanced viticultural management. The first part of this study sought to investigate the relationship between the different products of the flavonoid biosynthetic pathway (anthocyanins, flavonols and tannins), from two climatic regions (warm and cool) and determine their role in grape and wine quality. In collaboration with a major winery, whole Shiraz grapes were sampled at the weighbridge from a range of different vineyards from two climatic regions; warm (Riverland) and cool (McLaren Vale) in 2003 and 2004. A total of 80 grape samples were collected in each season and processed (i.e. 100 berries, separated into skin, seeds and juice, weighed and frozen). Anthocyanins and flavonols were measured, in triplicate, in skins by HPLC. Tannins were determined in the skins and seeds by two methods; phloroglucinol hydrolysis (HPLC) and protein precipitation (UV-VIS spectrophotometer). A comprehensive comparison of the two methods is discussed. In both years, the grapes from warm and cool climates formed two distinct data sets based on flavonoid composition. There was a correlation between anthocyanins and flavonols for both the warm and cool climate samples in both years, however those from the warm region had lower anthocyanin for a given level of flavonol. As expected, the level of tannin in the seeds was greater than in skin for all samples. In both years, there was a weak correlation between anthocyanin levels in the skin and skin tannins, but no relationship with seed tannins. These results suggest there is some co-ordination in the synthesis of anthocyanins, flavonols and skin tannins. Also, the two regions clearly separated based on yield and despite the weak correlations in both regions, the levels of total anthocyanins were inversely related to yield. In addition, there was no relationship with any of the flavonoids and grape quality, indicating the need for improvement in streaming fruit for quality using these flavonoid compounds. The second part of the study was to investigate the effect of bunch light exposure on flavonol synthesis and accumulation in Shiraz and Chardonnay grapes during development. Light-excluding boxes were applied to bunches at budburst. Boxes were removed at four sampling times; flowering, pre-veraison, veraison and harvest. At each sampling time, berry skins were sampled when the boxes were removed and then every second day (light induced), along with exposed controls for one week. Flavonol accumulation and flavonol synthase (VvFLS1) gene expression was determined by HPLC and Real Time-PCR (RT-PCR) respectively. As expected, for all four sampling times, flavonol accumulation and VvFLS1 expression in the boxed fruit was significantly less than bunches exposed to light. On removal of boxes at flowering, pre-veraison and veraison, flavonols accumulated to levels similar to that of the exposed control fruit over a period of 4-6 days. There was a significant increase in VvFLS1 expression 2 days after exposure to light in parallel with the accumulation of flavonols. At harvest, in Chardonnay, VvFLS1 expression peaked by day 4, while in Shiraz VvFLS1 expression increased linearly and was highest at day 6. In contrast to the results for the earlier sampling times, the total amount of flavonols accumulated at harvest was less than 50% of exposed controls in Chardonnay and Shiraz grapes. These results show that flavonols are able to be induced by bunch light exposure at different times during berry development, including times when flavonols are not normally being synthesised. This suggests bunch light exposure can override the developmental control of flavonol accumulation. To further investigate the light induced expression of VvFLS1 in grapevines the molecular mechanism of transcriptional control was explored. Using genomic walking PCR techniques, two Shiraz VvFLS1 promoter sequences were cloned and their sequences were analysed. These promoter sequences were ~800bp in length and were 99% identical. A putative MYB responsive element (MRE) and several light responsive elements (LRE) were identified in the promoter region of these genes. To functionally test the VvFLS1 promoter(s), a transient assay was developed in Chardonnay suspension cells. Cells were bombarded with constructs containing potential transcription factors and the VvFLS1 promoter(s), fused to a luciferase reporter vector. After 48hrs incubation in the dark, cells were harvested and luciferase activity measured as an indicator of VvFLS1 promoter activity. Of the different transcription factors tested with the VvFLS1 promoter(s) the highest luciferase activity was observed using AtMYB12 (a flavonol-specific regulator of AtFLS1 in Arabidopsis (Mehrtens et al. 2005). While this result shows activation of the VvFLS1 promoters by AtMYB12 and the development of a transient reporter assay for testing the VvFLS1 promoter(s) a grapevine transcription factor specific for VvFLS1 was sought. Two techniques were employed to identify potential transcription factor regulators of the VvFLS1 promoter(s). The first involved BLAST sequence search analysis in a grapevine expression (EST) database with AtMYB12 and the second involved using DNA microarray technology to identify candidate transcription factors that were up-regulated in light exposed Chardonnay cell suspension cultures. Thirteen potential transcription factors were identified and after correlative RT-PCR analysis (with VvFLS1 expression patterns) two candidates were selected for further isolation and characterisation. These results have made significant progress in unravelling the molecular mechanisms of regulation of the flavonol biosynthetic, however additional experiments are required to unravel the transcriptional control of flavonol biosynthesis. This investigation contributes to our knowledge of flavonoid synthesis in grapes; how it is coordinated, the relationship with wine quality, and the influence of light particularly on synthesis of flavonols. It also explores the molecular mechanisms of VvFLS1 control, through isolation of the VvFLS1 promoter and identification of potential transcription factors, which may regulate it. An understanding of the synthesis of flavonoids and how they may be coordinated, particularly in response to light, could be used to improve fruit quality by enhanced viticultural management. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1326767 / Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2008

abstract: Great advances have been made in the construction of photovoltaic (PV) cells and modules, but array level management remains much the same as it has been in previous decades. Conventionally, the PV array is connected in a fixed topology which is not always appropriate in the presence of faults in the array, and varying weather conditions. With the introduction of smarter inverters and solar modules, the data obtained from the photovoltaic array can be used to dynamically modify the array topology and improve the array power output. This is beneficial especially when module mismatches such as shading, soiling and aging occur in the photovoltaic array. This research focuses on the topology optimization of PV arrays under shading conditions using measurements obtained from a PV array set-up. A scheme known as topology reconfiguration method is proposed to find the optimal array topology for a given weather condition and faulty module information. Various topologies such as the series-parallel (SP), the total cross-tied (TCT), the bridge link (BL) and their bypassed versions are considered. The topology reconfiguration method compares the efficiencies of the topologies, evaluates the percentage gain in the generated power that would be obtained by reconfiguration of the array and other factors to find the optimal topology. This method is employed for various possible shading patterns to predict the best topology. The results demonstrate the benefit of having an electrically reconfigurable array topology. The effects of irradiance and shading on the array performance are also studied. The simulations are carried out using a SPICE simulator. The simulation results are validated with the experimental data provided by the PACECO Company. / Dissertation/Thesis / M.S. Electrical Engineering 2011

abstract: In geographical locations with hot-arid climates, sun control in buildings is one primary problem to solve for the building envelope design. Today's technological advances in building science bring with them the opportunity to design dynamic façade systems for sun radiation control and daylighting. Although dynamic systems can become an attractive visual element, they can be costly and challenging to maintain for building owners. Alternatively, fixed solar-shading systems can be designed to create dynamism in the façade of the building, while providing similar functionalities for sun control. The work presented in this project focuses on the use of a visual scripting editor for modeling software, Grasshopper, to develop a Solar Control Visual Script that evaluates building envelope surfaces with planar and non-uniform rational basis-spline (NURBS) forms and provides projections for fixed sun control systems. The design platform of Grasshopper allows individuals with no experience or prior computer coding education to build up programming-like capabilities; this feature permits users to discover new design possibilities within flexible frames that can contribute to the overall design being pursued, while also having an environmental response. The Solar Control Visual Script provides minimum sizing geometries that achieve shading in openings at a particular date and time of the year. The model for this method of analysis makes use of three components to derive the appropriate values for the projections of shading geometries: typical meteorological year (TMY) data, irradiation isotropic equations and shading profile angles equations for vertical and tilted surfaces. Providing an automatic visual of generated geometries uncovers the opportunity to test several model forms and reiterates the analysis when modifying control parameters. By employing building science as a set of environmental parameters, the design outcome bears a dynamic form that responds to natural force conditions. The optimized results promote an efficient environmental design solution for sun control as an integral alternative into the building envelope. / Dissertation/Thesis / M.S. Built Environment 2012

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / CoFeB thin films were produced using the technique of magnetronsputtering. Six samples were produced magnetic thin films with two different thicknesses, using different settings for shading masks. For each film were made two measurements of magnetization, a parallel to the easy axis of magnetization, and the other perpendicular to the axis. The films produced with shading masks non-magnetic show a deteriorated magnetic configuration compared to those produced with magnetic material with a cut. Different thicknesses of the films provide different values in the coercive field of the sample. The thicker films have an increase in the coercive field. With these results there is a possibility of making tunnel junctions measures aimed tunnel magneto-resistance with CoFeB films as an electrode. / Filmes finos de CoFeB foram produzidos utilizando a técnica de magnetron sputtering. Foram produzidas seis amostras de filmes finos magnéticos com duas espessuras diferentes, utilizando diferentes configurações para máscaras de sombreamento. Para cada filme foram feitas duas medidas de magnetização, uma paralela ao eixo fácil de magnetização, e outra perpendicular ao eixo. Os filmes produzidos com máscaras de sombreamento não magnéticas apresentam uma configuração magnética deteriorada em comparação aos produzidos com máscaras de material magnético com um corte. Diferentes espessuras dos filmes proporcionam diferentes valores do campo coercivo da amostra, para os filmes mais espessos temos um aumento no campo coercivo. Com esses resultados há uma possibilidade de confecção de junções túnel visando medidas de magneto resistência túnel com filmes de CoFeB como eletrodo.

Resumo: O sombreamento promovido por árvores constitui um dos melhores dispositivos externos para controle e redução dos efeitos da radiação solar. Natural e de baixo custo, este recurso é de extrema utilidade para o conforto térmico dos seres vivos, especialmente em países de clima quente, onde a incidência de radiação solar é alta. Este trabalho teve como objetivo avaliar a eficiência térmica do sombreamento natural proporcionado por diferentes espécies arbóreas, por meio de medições de varáveis climáticas e de índices de conforto térmico. A pesquisa foi desenvolvida no município de Botucatu, SP e foram avaliadas as sombras de nove indivíduos arbóreos, sendo três exemplares da espécie pau-terra-da-areia (Qualea dichotoma (Warm.) Stafl.), três da espécie chico-pires (Pithecolobium incuriale (Vell.) Benth.) e três da espécie copaíba (Copaifera langsdorffii Desf.). Foram registrados à sombra e a céu aberto os dados de temperatura do ar e umidade relativa, temperatura de ponto de orvalho e temperatura de globo negro e velocidade do vento, durante o verão, ao longo do dia, com leituras horárias entre 8h e 17h. Adotou-se o delineamento estatístico inteiramente casualizado (DIC). Os resultados foram avaliados por meio dos índices de conforto térmico ITU, ITGU, CTR, e por meio da avaliação para o dia crítico do período analisado. Concluiu-se que houve diferença estatística entre as espécies estudadas e de maneira geral a espécie copaíba foi a que apresentou um maior índice de redução da carga térmica de radiação, sendo a pau-terra-da-areia a que apresentou uma menor redução / Abstract: The shading promoted by trees constitutes one of the best external devices to control and to reduce the effects of solar radiation. Natural and economical, such resource is extremely useful to the thermal comfort of living creatures, especially in counties with hot weather, where the incidence of solar radiation is high. This work aimed at evaluating the thermal efficiency of the natural shading given by different species of trees through measurements of climatic variables and indexes of thermal comfort. The research was developed in Botucatu County (São Paulo) and the shade of nine trees were evaluated; three of the species pau-terra-da-areia (Qualea dichotoma (Warm.) Stafl.), three of the species chico-pires (Phithecolobium incuriale (Vell.) Benth.) and three of the species copaiba (Copaifera langsdorffii Desf.). The air temperature and the relative humidity, the dew point temperature, the globe temperature of Vernon, and the wind speed data were taken in the shade during summer, throughout the day with readings between 8 am and 5 pm in the shade and exposed sun. The completely random statistical design was adopted (DIC). The results were evaluated using thermal comfort indexes THI, BGHI, CTR and using evaluation on the critical day for the period analyzed. It was concluded that there was a statistical difference among the species used and, as a whole, the copaiba species was the one which presented the highest index of radiant thermal load reduction and the pau-terra-da-areia, the one which presented the lowest index / Orientador: Odivaldo José Seraphim / Coorientador: Iran José Oliveira da Silva / Banca: Lucila Chebel Labaki / Banca: Ana Maria Liner Pereira Lima / Mestre

Sistemas integrados têm sido apontados como alternativas ecologicamente apropriadas para recuperar a produtividade de pastagens tropicais degradadas, gerando benefícios tanto para o meio ambiente como para os animais. Apesar das diversas vantagens atribuídas aos sistemas integrados, existem ainda limitações técnicas que dificultam a otimização do processo produtivo, função da natureza complexa e multidisciplinar das interações entre seus componentes bióticos e abióticos. Existem, portanto, aspectos importantes que podem comprometer a produtividade do sistema, entre eles, as alterações na estrutura do dossel forrageiro e a menor produção de forragem, principalmente pela diminuição da radiação luminosa que chega ao sub-bosque. Partindo da hipótese que o dossel arbóreo irá determinar a quantidade e a qualidade de luz disponível para o sub-bosque e, assim, influenciar a estrutura do dossel forrageiro e a produção de forragem do capim-piatã manejado sob pastejo rotativo utilizando metas de interceptação luminosa (IL) prépastejo, o objetivo deste trabalho foi avaliar as características estruturais e o acúmulo de forragem de Brachiaria brizantha cv Piatã em sistema ILPF de dezembro de 2013 a julho de 2014. O estudo foi desenvolvido por meio de três experimentos realizados de forma concomitante para avaliar três regimes de luz: (1) capim-piatã cultivado em área livre de árvores (pleno sol; PS); (2) sombreamento gerado por meio de fileiras duplas de Eucalipto nas bordaduras dos piquetes (S1); e (3) sombreamento gerado por meio de quatro renques de fileiras triplas de Eucalipto dispostos dentro dos piquetes de forma alternada com porções de pasto (S2). Os regimes de luz S1 e S2 foram divididos em duas faixas de sombra (central e lateral) para descrição da variação da luz dentro dos piquetes e sua implicação sobre o padrão de crescimento das plantas. O período experimental foi dividido em três períodos de avaliação em função do índice pluviométrico registrado. Para estudar a influência das árvores sobre a medição de IL e sua implicação sobre o crescimento das plantas, o regime S2 foi manejado utilizando-se dois métodos de tomada da leitura de referência da luz incidente: leitura dentro (sob a copa das árvores) e fora (luz natural na ausência de árvores) da área experimental. Foram avaliadas as seguintes variáveis-resposta: altura, massa de forragem e sua composição morfológica, índice de área foliar, ângulo da folhagem, interceptação luminosa do dossel forrageiro, umidade do solo, índice de nutrição nitrogenada, taxa de acúmulo e produção de forragem. Os resultados indicaram que pastos sombreados possuíam altura 30% maior que pastos não sombreados, com colmos mais longos e delgados. A massa de forragem em pré-pastejo diminuiu com o aumento do nível de sombreamento e a composição morfológica se manteve praticamente estável entre os regimes luz. As mudanças morfológicas e estruturais resultaram em redução das taxas de acúmulo e da produção de forragem em torno de 50% no regime S1 e de 65% no regime S2 relativamente ao regime PS. O conjunto de resultados obtidos revela claramente que as metas de altura pré-pastejo desenvolvidas com base na condição de 95% de IL em pleno sol não podem e não devem ser utilizadas em sistemas integrados com árvores, especialmente aqueles em que a densidade de árvores é elevada, necessitando que metas específicas sejam produzidas para o manejo do pastejo naquelas condições. / Integrated production systems, such as the agrosilvopastoral systems, have been considered ecologically adequate alternatives in restoring the productivity of degraded tropical grasslands, as they generate benefits for both the environment and the grazing animals. Despite several advantages associated with the integrated systems, there are technical constraints that limit their optimization, due to the complex and multidisciplinary nature of the interactions between its biotic and abiotic components. In this context, there are important aspects that must be considered and that might influence the system\'s productivity, including changes in sward structure and herbage production due to decreased light availability under the trees. Based on the hypothesis that in a silvopastoral pastoral system the tree canopy determines the quantity and the quality of the light available for forages growing under the trees, and that this affects sward structural characteristics and herbage accumulation of rotationally grazed Piatã brachiariagrass managed using pre-grazing targets of canopy light interception during regrowth, the objective of this study was to evaluate the structural characteristics and the herbage accumulation of Brachiaria brizantha cv. Piatã in a crop-livestock-forest integration area from December 2013 to July 2014. The study comprised three simultaneous experiments to evaluate three light regimes: (1) Piatã brachiariagrass cultivated in the absence of trees (full natural light; PS); (2) shade produced by a double row of Eucaliptus trees on the edges of the paddocks (S1); and (3) shade produced by four triple rows of Eucaliptus with pasture in between them (S2). The S1 and S2 light regimes were divided into two shade strips (central and lateral) in order to describe the variation in light availability within the paddocks and its implications to plant growth. The experimental period was divided in three evaluation periods according to rainfall. In order to evaluate the influence of the trees on the measurement of sward canopy light interception and its implications on grass growth, paddocks under the S2 light regime were managed using two methods for taking the reference readings of the incident light: reading inside (under the tree canopy) and outside (full natural light) the experimental area. The following response variables were analyzed: sward height, herbage mass and plant-part composition, sward leaf area index, foliage angle, canopy light interception, soil moisture, grass nitrogen nutrition index, herbage accumulation rates and total herbage yield. The results indicate that shading, results in taller swards (30% increase in sward height pre-grazing) with longer and thinner stems. Pre-grazing herbage mass decreased with increasing shade levels and plant-part composition remained relatively constant across light regimes. Morphological and structural changes resulted in approximately 50 and 65% decrease in herbage accumulation rates and herbage yield under the S1 and S2 light regimes, respectively, in relation to PS. Pre-grazing target sward height recommendations based on the 95% canopy light interception under full light conditions are not suitable for integrated systems with trees, particularly those where tree density is high, emphasizing the need to devise specific management targets for use under those conditions.

Made available in DSpace on 2014-06-11T19:24:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-08-26Bitstream added on 2014-06-13T20:52:16Z : No. of bitstreams: 1 gurgel_em_me_botfca.pdf: 1540814 bytes, checksum: 2a27aab761192d5bcaf86f784c206c3c (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O sombreamento promovido por árvores constitui um dos melhores dispositivos externos para controle e redução dos efeitos da radiação solar. Natural e de baixo custo, este recurso é de extrema utilidade para o conforto térmico dos seres vivos, especialmente em países de clima quente, onde a incidência de radiação solar é alta. Este trabalho teve como objetivo avaliar a eficiência térmica do sombreamento natural proporcionado por diferentes espécies arbóreas, por meio de medições de varáveis climáticas e de índices de conforto térmico. A pesquisa foi desenvolvida no município de Botucatu, SP e foram avaliadas as sombras de nove indivíduos arbóreos, sendo três exemplares da espécie pau-terra-da-areia (Qualea dichotoma (Warm.) Stafl.), três da espécie chico-pires (Pithecolobium incuriale (Vell.) Benth.) e três da espécie copaíba (Copaifera langsdorffii Desf.). Foram registrados à sombra e a céu aberto os dados de temperatura do ar e umidade relativa, temperatura de ponto de orvalho e temperatura de globo negro e velocidade do vento, durante o verão, ao longo do dia, com leituras horárias entre 8h e 17h. Adotou-se o delineamento estatístico inteiramente casualizado (DIC). Os resultados foram avaliados por meio dos índices de conforto térmico ITU, ITGU, CTR, e por meio da avaliação para o dia crítico do período analisado. Concluiu-se que houve diferença estatística entre as espécies estudadas e de maneira geral a espécie copaíba foi a que apresentou um maior índice de redução da carga térmica de radiação, sendo a pau-terra-da-areia a que apresentou uma menor redução / The shading promoted by trees constitutes one of the best external devices to control and to reduce the effects of solar radiation. Natural and economical, such resource is extremely useful to the thermal comfort of living creatures, especially in counties with hot weather, where the incidence of solar radiation is high. This work aimed at evaluating the thermal efficiency of the natural shading given by different species of trees through measurements of climatic variables and indexes of thermal comfort. The research was developed in Botucatu County (São Paulo) and the shade of nine trees were evaluated; three of the species pau-terra-da-areia (Qualea dichotoma (Warm.) Stafl.), three of the species chico-pires (Phithecolobium incuriale (Vell.) Benth.) and three of the species copaiba (Copaifera langsdorffii Desf.). The air temperature and the relative humidity, the dew point temperature, the globe temperature of Vernon, and the wind speed data were taken in the shade during summer, throughout the day with readings between 8 am and 5 pm in the shade and exposed sun. The completely random statistical design was adopted (DIC). The results were evaluated using thermal comfort indexes THI, BGHI, CTR and using evaluation on the critical day for the period analyzed. It was concluded that there was a statistical difference among the species used and, as a whole, the copaiba species was the one which presented the highest index of radiant thermal load reduction and the pau-terra-da-areia, the one which presented the lowest index

Dans cette thèse sont présentées deux méthodes visant à obtenir automatiquement une description tridimensionnelle des mouvements d'une main étant donnée une séquence vidéo monoculaire de cette main. En utilisant l'information fournie par la vidéo, l'objectif est de déterminer l'ensemble des paramètres cinématiques nécessaires à la description de la configuration spatiale des différentes parties de la main. Cet ensemble de paramètres est composé des angles de chaque articulation ainsi que de la position et de l'orientation globale du poignet. Ce problème est un problème difficile. La main a de nombreux degrés de liberté et les auto-occultations sont omniprésentes, ce qui rend difficile l'estimation de la configuration des parties partiellement ou totalement cachées. Dans cette thèse sont proposées deux nouvelles méthodes qui améliorent par certains aspects l'état de l'art pour ce problème. Ces deux méthodes sont basées sur un modèle de la main dont la configuration spatiale est ajustée pour que sa projection dans l'image corresponde au mieux à l'image de main observée. Ce processus est guidé par une fonction de coût qui définit une mesure quantitative de la qualité de l'alignement de la projection du modèle avec l'image observée. La procédure d'ajustement du modèle est réalisée grâce à un raffinement itératif de type descente de gradient quasi-newton qui vise à minimiser cette fonction de coût.Les deux méthodes proposées diffèrent principalement par le choix du modèle et de la fonction du coût. La première méthode repose sur un modèle de la main composé d'ellipsoïdes et d'une fonction coût utilisant un modèle de la distribution statistique de la couleur la main et du fond de l'image.La seconde méthode repose sur un modèle triangulé de la surface de la main qui est texturé est ombragé. La fonction de coût mesure directement, pixel par pixel, la différence entre l'image observée et l'image synthétique obtenue par projection du modèle de la main dans l'image. Lors du calcul du gradient de la fonction de coût, une attention particulière a été portée aux termes dûs aux changements de visibilité de la surface au voisinage des auto-occultations, termes qui ont été négligés dans les méthodes préexistantes.Ces deux méthodes ne fonctionnement malheureusement pas en temps réel, ce qui rend leur utilisation pour l'instant impossible dans un contexte d'interaction homme-machine. L'amélioration de la performance des ordinateur combinée avec une amélioration de ces méthodes pourrait éventuellement permettre d'obtenir un résultat en temps réel. / In this thesis we propose two methods that allow to recover automatically a full description of the 3d motion of a hand given a monocular video sequence of this hand. Using the information provided by the video, our aimto is to determine the full set of kinematic parameters that are required to describe the pose of the skeleton of the hand. This set of parameters is composed of the angles associate to each joint/articulation and the global position and orientation of the wrist. This problem is extremely challenging. The hand as many degrees of freedom and auto-occlusion are ubiquitous, which makes difficult the estimation of occluded or partially ocluded hand parts.In this thesis, we introduce two novel methods of increasing complexity that improve to certain extend the state-of-the-art for monocular hand tracking problem. Both are model-based methods and are based on a hand model that is fitted to the image. This process is guided by an objective function that defines some image-based measure of the hand projection given the model parameters. The fitting process is achieved through an iterative refinement technique that is based on gradient-descent and aims a minimizing the objective function. The two methos differ mainly by the choice of the hand model and of the cost function.The first method relies on a hand model made of ellipsoids and a simple discrepancy measure based on global color distributions of the hand and the background. The second method uses a triangulated surface model with texture and shading and exploits a robust distance between the synthetic and observed image as discrepancy measure.While computing the gradient of the discrepancy measure, a particular attention is given to terms related to the changes of visibility of the surface near self occlusion boundaries that are neglected in existing formulations. Our hand tracking method is not real-time, which makes interactive applications not yet possible. Increase of computation power of computers and improvement of our method might make real-time attainable.