Submitted by (edna.saturno@ufrpe.br) on 2016-05-24T16:31:30Z No. of bitstreams: 1 Helia Cavalcanti Correa Teixeira.pdf: 722085 bytes, checksum: 907e5992b3d6cc6b52100960509a0841 (MD5) / Made available in DSpace on 2016-05-24T16:31:31Z (GMT). No. of bitstreams: 1 Helia Cavalcanti Correa Teixeira.pdf: 722085 bytes, checksum: 907e5992b3d6cc6b52100960509a0841 (MD5) Previous issue date: 2014-05-06 / This study goals to analyze the relation of commercialization system with causes of losses of leafy vegetables: lettuce, chive and coriander traded by producers, middlemen, Central Supply and Logistics of Pernambuco (CEASA) and private supermarkets in Recife. We specifically sought to identify the main causes of losses in the commercialization system; To quantify and to value the physical and monetary losses caused in the marketing process; To check the retailer’s and wholesaler’s commercialization margin. A theoretical basis was presented about agricultural market, marketing channels and flows, losses in production and marketing of hardwoods, horticulture, production of leafy vegetables, logistics, market structure, pricing system. In the study data collection was carried out through visits and semi-structured interviews with farmers: the leafy vegetables lettuce, scallions and cilantro in Vitória de Santo Antão in the settlement of Natuba with middlemen, with the permittees of supply structures and supermarkets Grand Reef. We also implemented a research questionnaire to identify the monetary losses, physical losses, causes of losses, among other issues part of the chain of marketing of leafy greenery. The results of this study demonstrate that the losses in trading occur throughout this process and consequences of these losses are reflected in the budget of the end user, due to increase in price. According to the producers, there are physicall loses of 73,13% of the three hardwoods studied, and there is a total loss of 40,22% of hardwoods to the middleman, while for the retailer and wholesaler from CEASA there is a loss of 34.48% of leafy, and at last there is a loss of 25,36% of hardwood on the supermarkets. / O presente estudo tem como premissa analisar a relação entre o sistema de comercialização e as causas de perdas das hortaliças folhosas: alface, cebolinha e coentro, comercializados entre os produtores, os atravessadores, a Central de Abastecimento e Logística de Pernambuco (CEASA) e os supermercados. Especificamente, buscou-se verificar as principais causas das perdas no sistema de comercialização; Quantificar e valorar as perdas físicas e monetárias provocadas no processo de comercialização; Verificar a margem de comercialização do varejista e atacadista. Um aporte teórico sobre: mercado agrícola, canais e fluxos de comercialização, perdas na produção e comercialização de folhosas, olericultura, sistema de produção das hortaliças folhosas, logística, estrutura de mercado, formação de preço foi apresentado. No estudo a coleta de dados, foi realizada por meio de visitas e entrevistas semiestruturadas com os produtores: das hortaliças folhosas da alface, da cebolinha e do coentro no Município de Vitória de Santo Antão no assentamento de Natuba, com os atravessadores, com os permissionários da CEASA e com os supermercados do Grande Recife. Realizou-se também a aplicação do questionário de pesquisa de campo, com o objetivo de fazer um levantamento: das perdas monetárias, perdas físicas, causas das perdas, entre outras questões para cada ator integrante do processo de comercialização das hortaliças folhosas. Os resultados encontrados desse estudo demonstram que as maiores causas das perdas na comercialização estão associadas às doenças relacionadas: ao cultivo, às condições climáticas, aos produtos que machucam durante o transporte, o manuseio do cliente. Em relação aos produtores, perde-se fisicamente 73,13% das três folhosas estudadas, a perda total das folhosas para o atravessador confere 40,22%, já para o varejista e atacadista permissionário do CEASA configura uma perda de 34,48% de folhosas e por último tem-se uma perda de 25,36% das folhosas para o supermercado.

La durée de vie des isolants synthétiques de câbles électriques installés en centrale nucléaire est l'une des préoccupations majeurs d'EDF R&D. Pour répondre à cette question, un modèle cinétique de vieillissement radiothermique a été développé pour une matrice EPDM stabilisée par un mélange phénol/HALS dans cette thèse. Ce modèle est dérivé d'un schéma mécanistique d'oxydation, établi dans une étude précédente pour la matrice PE pure, mais complété par les principales réactions de stabilisation des deux types d'antioxydants. Sa validité a été vérifiée avec succès pour une matrice EPDM pure et stabilisée par 0,1, 0,3 et 0,5% w/w de chaque type d'antioxydants, mais aussi par (0-0,3), (0,1-0,2), (0,15-0,15), (0,2-0,1), (0,3-0)% w/w de mélange des deux antioxydants. Le modèle cinétique prédit de manière satisfaisante la grande majorité des courbes cinétiques de consommation chimique des fonctions phénoliques et des fonctions amines, mais aussi des courbes d'accumulation des produits carbonyles dans l'air entre 140 et 160°C en absence d'irradiation γ, mais aussi sous 0,1 kGy/h-45°C, 1 kGy/h-51,5 °C et 10 kGy/h-63,5 °C. Différentes voies possibles d'amélioration sont proposées. / The lifetime prediction of synthetic insulations of electrical cables installed in nuclear power plants is one of the main concerns of EDF R&D. To answer this question, a radiothermal ageing kinetic model has been developed for an EPDM matrix stabilized by a phenol/HALS blend in this study. This model is derived from an oxidation mechanistic scheme, established in a previous study for the neat PE matrix, but completed by the main stabilization reactions of both antioxidants. Its validity has been checked successfully for an EPDM matrix unstabilized and stabilized by 0.1, 0.3 and 0.5% w/w of each antioxidant, but also by (0-0.3), (0.1-0.2), (0.15-0.15), (0.2-0.1), (0.3-0)% w/w of both antioxidants. The kinetic model predicts satisfyingly the large majority of kinetic curves of chemical consumption of phenolic and amine functions, but also the kinetic curves of carbonyl group build-up in air between 140 and 160°C in the absence of γ irradiation, but also under 0.1 kGy/h-45°C, 1 kGy/h-51.5 °C et 10 kGy/h-63.5 °C. Various possible ways of improvement are proposed.

Dans l’industrie automobile, la tâche de dimensionnement des faisceauxélectriques consiste à définir au plus juste la section du conducteur métallique, ce qui augmente l’échauffement du câble par effet Joule. Or, les polymères sont les matériaux d’isolation les plus utilisés malgré leur grande sensibilité au vieillissement thermique. C’est pourquoi leur durabilité en environnement automobile doit être déterminée pour pouvoir ensuite être prise en compte lors du dimensionnement des faisceaux électriques. Dans ce but, nous avons analysé le vieillissement thermique de deux gaines d’isolation en PVC et PELX dans l’air aux températures des essais de qualification (typiquement entre 100°C et 200°C). Dans le cas du PVC, le principal mécanisme de vieillissement est la perte physique du plastifiant. La fragilisation du matériau intervient orsque la concentration de la phase de plastifiant non-dissoute, qui est ispersée sous forme de nodules dans la matrice PVC faiblement plastifiée, atteint une valeur critique de l’ordre de 0,2 mol.L-1. En revanche, dans le cas du PELX, l’oxydation conduit à la fragilisation du matériau au terme de la période d’induction, c’est-à-dire dès que la totalité des antioxydants a été consommée. Pour chaque gaine d’isolation, un modèle cinétique a été dérivé des mécanismes de vieillissement et un critère de fin de vie structural a été établi. Ce modèle donne accès au potentiel de vie restant et à la durée de vie des câbles électriques en conditions de service. / In the automotive industry, the issue of electrical harness dimensioning consists in an optimal definition of the cross-section of metallic conductors, which increases the wire heating due to Joule effect. However, polymers are the most used materials for insulation despite their high sensitivity to thermal ageing. That is the reason why their durability must be determined in automotive environment to be then taken into account during the dimensioning of electrical harness. For this purpose, we analyzed the thermal aging of two insulation sheaths made of PVC and XLPE in air at temperatures of qualification tests (typically between 100°C and 200°C). For PVC, the main ageing mechanism is the physical loss of plasticizer. The material embrittlement occurs when the concentration of the non-dissolved plasticizer phase, which is dispersed as nodules in the weakly plasticized PVC matrix, reaches a critical value of about 0,2 mol.L-1. In contrast, for XLPE, oxidation leads to material embrittlement at the end of the induction period, i.e. when the totality of antioxidants has been consumed. For each insulation sheath, a kinetic model was derived from the ageing mechanisms and a structural end-of-life criterion was established. This model gives access to the remaining life potential and lifetime of electrical cables in service conditions.