A partir de l’étude d’une structure composite multifonctionnelle prédéfinie, cette thèse a pour objectif l’analyse du comportement thermomécanique et des modes d’endommagement d’une structure composite intégrant des conducteurs électriques. Des éprouvettes représentatives sont fabriquées et testées sous différentes conditions mécaniques, thermiques et électriques. L’influence des chargements mécaniques hors-plan, et plus particulièrement d’un impact basse énergie, sur la fonctionnalité électromécanique de la structure est ensuite étudiée. Des mesures de résistance électrique et te tension de claquage sont réalisées afin de déterminer les performances électriques post-impact de la structure. L’échauffement résistif interne des conducteurs, conjugué à l’environnement thermique d’une structure aéronautique nous invite finalement à étudier le comportement thermomécanique de tels assemblages multicouches et multi-matériaux. Nous présentons donc une méthodologie de caractérisation du comportement thermomécanique d’un assemblage sandwich multicouche via l’analyse de ses composants pris séparément et caractérisés par des analyses mécaniques dynamiques (DMA). La contribution majeure de ce travail réside dans la détermination de critères de dégradation électrique, et de dimensionnement, pour le développement de structures composites intégrant des conducteurs électriques. / From the study of a particular multifunctional composite structure, this thesis aims at analyzing the thermomechanical behavior and failure modes of a composite structure embedding electrical wires. Representative test specimens embedding flat electrical cables are manufactured and tested under various conditions. The influence of out-of-plane loadings, and especially of low energy impacts on the electro-mechanical functionality of the structure is then investigated with both experimental and numerical considerations. Post impact electrical tests such as resistance measurements and dielectric strength tests are carried out to investigate on the post-impact electrical performances of the structure. Then, resistive heating of the embedded electrical components combined to the thermal environment of an aerospace structure lead us to further investigate on the thermo-mechanical behaviour of such multi-layered multi-materials structures. Hence, a methodology using Dynamic Mechanical Analysis (DMA) testings is developed to characterize both the temperaturedependent stiffness of the constituents, and the resulting thermo-mechanical behaviour of the assembly. The main contribution of this work consists in determining electrical degradation and sizing criteria for the development of robust composite structures embedding electrical wires.

Cette thèse porte sur le présentéisme au travail, phénomène qui désigne le comportement des salariés qui se rendent à leur travail alors qu’ils sont malades. Notre objectif est de tenter de répondre à la question suivante : quel est le processus de décision qui conduit un individu temporairement affecté par une maladie à décider de s’absenter et/ou de se présenter à son travail malgré son état de santé ? Plus précisément, notre objectif est d’étudier les déterminants qui conduisent un salarié malade à choisir entre les trois possibilités suivantes : une absence totale (le salarié s'absente alors pendant toute la durée de l’épisode de maladie), une présence totale (il travaille pendant toute la durée de l’épisode de maladie), une présence partielle (il combine absence et présence au sein d'un même épisode de maladie). A notre connaissance, cette troisième possibilité n’a jamais été envisagée dans la littérature, cette dernière se limitant à distinguer uniquement l’absence et la présence. Afin d'analyser le choix entre ces trois possibilités, nous avons conçu et réalisé une enquête permettant d'identifier, pour chaque salarié enquêté, son dernier épisode de maladie, et pour cet épisode de maladie, la décision prise entre absence totale, présence totale et présence partielle. Comme nous le montrerons, la prise en compte des combinaisons entre absence et présence au sein d’un même épisode de maladie modifie sensiblement la mesure du présentéisme telle qu’elle est appréhendée dans la littérature empirique sur le phénomène. Nos résultats mettent également en évidence le rôle prédominant des caractéristiques de la maladie dans le comportement des salarié, et notamment le rôle de la durée de l’épisode de maladie. Ils montrent enfin l’effet sur la décision, d’une part, des risques que l’individu prend sur sa santé future s’il décide de choisir le présentéisme, total ou partiel et, d’autre part, des risques qu’il prend sur son emploi et/ou l’évolution de sa carrière s’il décide de s’absenter tout ou partie de l’épisode de maladie / This thesis focuses on presenteeism at work, a phenomenon that refers to the behavior of employees who go to work although they are sick. Our goal is to try to answer the following question: what is the decision process that leads an individual who is temporarily affected by sickness to decide to report sick and/or to attend despite the illness? Specifically, our goal is to study the determinants that lead a sick employee to choose between three options: a total absence (the employee is absent for the whole duration of the spell of illness), total attendance (he works for the whole duration), partial attendance, that is to say a combination of absence and attendance in the same spell of illness. To our knowledge, this third possibility has never been considered in the literature, which only distinguishes absence and attendance. To analyze the choice between these three possibilities, we have designed and conducted a survey to identify, for each employee in the survey, his last spell of illness, and for it, the decision between total absence, total attendance and partial attendance. As we will show, taking into account combinations of absence and attendance in the same spell of illness significantly modifies the measure of presenteeism, in comparison to the way it is generally measured in the empirical literature. Our results also highlight the predominant role of illness characteristics in the behavior of the employee, especially the role of the duration of the spell of an illness. Our results also show the effect on the decision of, one the one hand, risks that the employee takes for his future health if he decides to attend, totally or partially and, on the other hand, risks he takes for his job and for his future wage if he decides to report sick leave during the full spell of illness or during just a part of it

Les impacts sur structures composites peuvent fortement diminuer leur résistance résiduelle sans laisser de marque visible sur la surface extérieure. Dans le domaine aéronautique, un seuil minimum de détection de l’endommagement d’impact est défini, basé sur l’indentation permanente laissée par l’impact. En deçà de ce seuil, la structure doit résister à un chargement défini : c’est la notion de tolérance aux dommages d’impact. Dimensionner numériquement une structure composite en tenant compte des aspects détectabilité et tolérance aux dommages nécessite donc de savoir modéliser à la fois l’impact, l’indentation permanente et la résistance résiduelle sous compression.Ces travaux se focalisent sur la modélisation numérique des composites stratifiés formés de plis unidirectionnels. L’objectif est d’établir un modèle prédictif de la tenue résiduelle après impact. Une étude expérimentale a été réalisée afin d’étudier le scénario d’endommagement à l’impact et sous compression après impact (CAI), et de fournir des résultats expérimentaux pour valider les modèles numériques.Une modélisation par éléments finis avec une approche de type Discrete Ply Model (DPM) est effectuée, basée sur des travaux précédents. Le modèle d'impact est amélioré et validé sur différentes séquences d'empilement pour assurer la robustesse du modèle. Des essais de flexion trois points spécifiques sont réalisés pour apporter une meilleure compréhension de la formation de l'indentation permanente. Un nouveau modèle d'indentation permanente est alors proposé et appliqué dans le modèle d'impact. Enfin, un modèle de CAI est construit pour prédire la résistance résiduelle. Les trois étapes : impact, indentation et CAI sont combinées au sein d’un unique modèle. / Impacts on composite structures can greatly reduce their residual strength without leaving a visible mark on the outer surface. In aeronautics, a minimum detection threshold of the impact damage is defined, based on the permanent indentation left after impact. Below this threshold, the structure must withstand a defined load: it is the notion of impact damage tolerance. The numerical design of a composite structure taking into account aspects such as detectability and damage tolerance thus requires to know how to represent impact, permanent indentation and residual strength under compression.This work focuses on the numerical modeling of composite laminates made of unidirectional plies. The objective is to develop a predictive model of post-impact residual strength. An experimental study was conducted to investigate the damage scenario during impact and compression after impact (CAI), and provide experimental data to validate the simulations.A finite element modeling with a Discrete Ply Model (DPM) approach is performed based on previous work done at the laboratory. The impact model is improved and validated on different stacking sequences to ensure the robustness of the model. Specific three-point bending tests are performed to have a better understanding of the formation of permanent indentation. A new model of permanent indentation is then proposed and applied in the impact model. Finally, a model is built to predict CAI residual strength. The three steps: impact, indentation and CAI are combined into a single model.

No description available.

African agriculture has attracted increased global policy attention over the last 10 years due to concerns over both food security and economic growth. In this context, social impact investing (SII)—where investors use financial models to achieve positive social impacts as well as financial returns—is presented as a viable means of financing agricultural development in the context of reduced public funding This thesis is concerned with how SII (and its understandings, assumptions, and models of agricultural development) interact with smallholder farming in Tanzania. I unpack how the concept of SII takes shape, how it is translated into the Tanzanian context, and how it interacts with farmer livelihoods through a case study of Cheetah Development in Lower Kilolo District. I take a political ecology approach drawing mainly on qualitative methods. The concept of assemblages is employed to investigate how diverse actors enter into relationships, how those relationships hold together, and how they fall apart. I focus on three key analytical themes: power (discursive, disciplinary, and institutional), moral economies, and the role of socio-material entities. My findings show that SII is being driven by the pursuit for new profit frontiers and concerns over business risks, and also by a belief that a more ethical capitalist economy can be built. This has resulted in a narrative of ‘Africa rising’. How exactly ‘social impact’ is being defined and the motivations for pursuing it, however, differ widely within SII. To investigate how agricultural SII is translated in Tanzania I focus on Cheetah Development, an American social impact investor that provides agricultural inputs on credit to smallholder farmers and attempts to involve them in new maize value chains. Cheetah’s model identifies existing maize value chains centred around middlemen as features of an immoral capitalism. It also views smallholders as not only lacking market access and inputs, but also lacking in business-orientated mindsets. The Cheetah model builds various mechanisms to discipline farmers and render them bankable. Through examining farmer livelihoods, I find that farmers conduct diverse livelihood activities, and maize plays a variety of roles in village life. Farmer livelihoods are underpinned by a moral economy involving flexible relations of borrowing and lending. I conclude that assumptions of ethical capitalism embedded in the Cheetah model clash with farmer livelihoods and their conceptions of just socio-economic relationships.

Made available in DSpace on 2014-06-11T19:26:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-07-18Bitstream added on 2014-06-13T20:14:49Z : No. of bitstreams: 1 sandoval_ms_me_rcla.pdf: 689985 bytes, checksum: f333029b423c9df4992d4070398b119c (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A avaliação da significância dos impactos ambientais continua a ser um importante componente crítico ainda mal compreendido da prática da avaliação de impactos ambientais. Este trabalho é um estudo sobre as conclusões de uma revisão bibliográfica sobre a avaliação e comunicação de avaliação do impacto ambiental praticada no Brasil. É dada especial atenção para a importância da utilização de critérios, padrões e métodos de avaliação de impactos ambientais que pretendendo incorporar mais eficiência nos estudos de impacto ambiental. Assim, o objetivo desta pesquisa foi a realização de uma proposta, incluindo o desenvolvimento de procedimentos e aplicar na avaliação de impactos ambientais situações relativas à sua formulação, aplicação e interpretação da significância dos critérios, conclusões e recomendações pertinentes para respeitar o objetivo da avaliação de impacto ambiental que é garantir a viabilidade ambiental das atividades humanas. / The evaluation of the significance of environmental impacts remains an important critical yet poorly understood component of environmental impact assessment practice. This work is a study upon the findings of a bibliographic review about the evaluation and communication of environmental impact assessment in Brazil practice. Particular attention is given to the use of significance criteria, thresholds and EIA methodologies intending to incorporate more efficiency of environmental impact statement. Thus, the aim of this research was the accomplishment of a proposal including the development of procedures to apply in EIA issues surrounding the formulation, application and interpretation of significance criteria, conclusions and recommendations relevant to respect the aim of EIA that in provide environmental viability of men activities.

Resumo: A formação do reservatório de Itaipu propiciou a colonização para o curso superior do rio Paraná de mais de 15 espécies de peixes, incluindo as arraias do gênero Potamotrygon, as quais já se estabeleceram na área do alto rio Paraná, com ocorrências comprovadas nos reservatórios de Porto Primavera e Jupiá, nos rios Paranapanema, Sucuriú e baixo Tietê. A região de estudo apresenta atividades diretamente ligadas ao rio, como prática de esportes náuticos, pesca e formação de balneários. Assim, sua ocorrência pode configurar uma preocupação para a população local. Em entrevistas realizadas, percebe-se como esse animal está conseguindo se dispersar e estabelecer no ambiente. Esta dissertação teve como objetivos: conhecer os impactos que esses animais causam à região do alto curso do rio Paraná e alguns de seus afluentes, estimar o conhecimento da população ribeirinha e demais freqüentadores dos locais em relação às arraias, pesquisar sobre a utilização destes animais para fins comerciais e consumo da carne, relatar a ocorrência de acidentes e obter informações sobre estórias, mitos e dúvidas a respeito do animal em estudo. As comunidades tradicionais têm conhecimentos sobre as arraias, ao contrário dos demais frequentadores dos rios, sendo estas, consideradas animais perigosos por ambos. Entre as conclusões, verificouse a falta de medidas que protejam os balneários e praias da região contra acidentes. A carne de arraia não tem valor comercial algum, assim como as pessoas da região não têm o costume de consumir este tipo de alimento. As estórias locais geram mais temor, discriminação e repulsa ao animal. É necessário um trabalho de educação ambiental que faça com que as pessoas reflitam sobre a questão do aparecimento desses animais, pois isto ajudaria a diminuir o temor e preconceito que existe com as arraias de água doce / Abstract: The formation of the Itaipu reservoir gave way to the colonization of the upper part of the Paraná river for more than 15 species of fish, including the freshwater stingray of the genus Potamotrygon, which had already established in the high area of the river Paraná, with occurrences proved in the reservoirs of Porto Primavera and Jupiá powerplants, in the Paranapanema, Sucuriú e low Tietê rivers. The region of study presents activities directly related to the river, such as the practice of nautical sports, fishing and formation of bathing places. So, its occurrence may be a concern for local people. In interviews, it was noticed how the animal is able to disperse and establish in the environment. This dissertation aimed to: know the impacts that these animals cause in the region of the upper course of the Paraná river and some of its tributaries, measure the knowledge of the riverside population and other regular visitors of the place about the freshwater stingray, research the use of these animals for trade and consume of meat, report the occurrence of accidents and information on the stories, myths and doubts about the animal studied. The traditional communities have knowledge about the freshwater stingray, otherwise the regular visitors of the rivers do not have it, but the animals are considered dangerous by both groups. Among the conclusions, there was the lack of measures to protect the region's bathing places and beaches from accidents. The meat of freshwater stingray is not a commercial, and the people of the region haven't the habit of consuming such food. The local stories generate more fear, discrimination and rejection for the animal. It is necessary a work in environmental education capable to make people reflect on the question of the appearance of these animals, as this would help reduce the fear and prejudice that the freshwater stingray can cause / Orientador: Vidal Haddad Junior / Coorientador: Maria José Alencar Vilela / Banca: Virgínia Sanches Uieda / Banca: Maria Elisa Rebustini / Mestre

Made available in DSpace on 2014-06-11T19:30:12Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-09-25Bitstream added on 2014-06-13T20:00:06Z : No. of bitstreams: 1 forster_oc_me_botib.pdf: 6667062 bytes, checksum: 724b6cbe45da8c137038e3a7f87a007a (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A formação do reservatório de Itaipu propiciou a colonização para o curso superior do rio Paraná de mais de 15 espécies de peixes, incluindo as arraias do gênero Potamotrygon, as quais já se estabeleceram na área do alto rio Paraná, com ocorrências comprovadas nos reservatórios de Porto Primavera e Jupiá, nos rios Paranapanema, Sucuriú e baixo Tietê. A região de estudo apresenta atividades diretamente ligadas ao rio, como prática de esportes náuticos, pesca e formação de balneários. Assim, sua ocorrência pode configurar uma preocupação para a população local. Em entrevistas realizadas, percebe-se como esse animal está conseguindo se dispersar e estabelecer no ambiente. Esta dissertação teve como objetivos: conhecer os impactos que esses animais causam à região do alto curso do rio Paraná e alguns de seus afluentes, estimar o conhecimento da população ribeirinha e demais freqüentadores dos locais em relação às arraias, pesquisar sobre a utilização destes animais para fins comerciais e consumo da carne, relatar a ocorrência de acidentes e obter informações sobre estórias, mitos e dúvidas a respeito do animal em estudo. As comunidades tradicionais têm conhecimentos sobre as arraias, ao contrário dos demais frequentadores dos rios, sendo estas, consideradas animais perigosos por ambos. Entre as conclusões, verificouse a falta de medidas que protejam os balneários e praias da região contra acidentes. A carne de arraia não tem valor comercial algum, assim como as pessoas da região não têm o costume de consumir este tipo de alimento. As estórias locais geram mais temor, discriminação e repulsa ao animal. É necessário um trabalho de educação ambiental que faça com que as pessoas reflitam sobre a questão do aparecimento desses animais, pois isto ajudaria a diminuir o temor e preconceito que existe com as arraias de água doce / The formation of the Itaipu reservoir gave way to the colonization of the upper part of the Paraná river for more than 15 species of fish, including the freshwater stingray of the genus Potamotrygon, which had already established in the high area of the river Paraná, with occurrences proved in the reservoirs of Porto Primavera and Jupiá powerplants, in the Paranapanema, Sucuriú e low Tietê rivers. The region of study presents activities directly related to the river, such as the practice of nautical sports, fishing and formation of bathing places. So, its occurrence may be a concern for local people. In interviews, it was noticed how the animal is able to disperse and establish in the environment. This dissertation aimed to: know the impacts that these animals cause in the region of the upper course of the Paraná river and some of its tributaries, measure the knowledge of the riverside population and other regular visitors of the place about the freshwater stingray, research the use of these animals for trade and consume of meat, report the occurrence of accidents and information on the stories, myths and doubts about the animal studied. The traditional communities have knowledge about the freshwater stingray, otherwise the regular visitors of the rivers do not have it, but the animals are considered dangerous by both groups. Among the conclusions, there was the lack of measures to protect the region's bathing places and beaches from accidents. The meat of freshwater stingray is not a commercial, and the people of the region haven’t the habit of consuming such food. The local stories generate more fear, discrimination and rejection for the animal. It is necessary a work in environmental education capable to make people reflect on the question of the appearance of these animals, as this would help reduce the fear and prejudice that the freshwater stingray can cause

No description available.

Plastics fuel tanks have been used successfully abroad ; metal counterparts are still predominant in this country plastics tanks have to satisfy stringent performance regulations : low temperature impact tests ; permeability ; and fire resistance. Blow moulded high density polyethylene (HDPE) fuel tanks have superior strength to mass ratio compared with metal equivalents (the density of steel is about 8000 kg/m3 compared with HDPE, which has a density of under 1000 kg/m3 ). HDPE will tend to drip in a fire situation, thus reducing explosion risk. HDPE is the chosen material because it possesses inherent properties suitable for the blow moulding process : it has a high viscosity at low stresses ; and is highly inert. Rotational moulded HDPE fuel tanks can also be considered. However, these are shown to have inferior properties when compared with blow moulded tanks ; attraction of rotational moulding is the cheapness of equipment. Petrol immersion was found to enhance impact properties of HDPE, although yield stresses were lowered slightly. The thickness distributions of blow moulded fuel tanks were found to vary ; this is because of the present difficulty of predicting parison behaviour with respect to time. Thickness is important because of impact strength and permeation considerations. Impact properties of fuel tanks were assessed ; peak force of impact was found to be heavily dependent on thickness (raised to the power 1.1) and temperature of mould in the blow moulding process (a low mould temperature led to inferior properties). Pinch-offs were found to be particularly detrimental to impact properties. Cooling behaviour was investigated. With the aid of a cooling model for blow mouldings, it was found that a warm mould (40·C) could be used with internal air circulation to obtain a cooling time the same as that with a cold mould and no air circulation. Thus optimising mechanical strength and maintaining economic viability. Welding of injection moulded fittings to the main blow moulded body of the fuel tank was found to be faulty, in all of the tanks examined ; many weld failures have been reported in use. This work determines optimum welding conditions for HDPE grades, these are Rigidex H060-45P and Lupolen 426l-A.