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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
131

Microscopic Characterisation of Solar Cells : An Electron Microscopy Study of Cu(In,Ga)Se2 and Cu2ZnSn(S,Se)4 Solar Cells

Wätjen, Jörn Timo January 2013 (has links)
The sun provides us with a surplus of energy convertible to electricity using solar cells. This thesis focuses on solar cells based on chalcopyrite (CIGSe) as well as kesterite (CZTS(e)) absorber layers. These materials yield record efficiencies of 20.4 % and 11.1 %, respectively. Especially for CZTS(e), the absorber layers often do not consist of one single desired phase but can exhibit areas with deviating material properties, referred to as secondary phases. Furthermore, several material layers are required for a working solar cell, each exhibiting interfaces. Even though secondary phases and interfaces represent a very small fraction of the solar cell they can have a profound influence on the over-all electrical solar cell characteristics. As such, it is crucial to understand how secondary phases and interfaces influence the local electrical characteristics. Characterising secondary phases and interfaces is challenging due to their small sample volume and relatively small differences in composition amongst others. This is where electronmicroscopy, especially transmission electron microscopy, offers valuable insight to material properties on the microscopic scale. The main challenge is, however, to link these material properties to the corresponding electrical characteristics of a solar cell. This thesis uses electron beam induced current imaging and introduces a new method for JV characterisation of solar cells on the micron scale. Combining microscopic structural and electrical characterisation techniques allowed identifying and characterising local defects found in the absorber layer of CIGS solar cells after thermal treatment. Furthermore, CZTSe solar cells in this thesis exhibited a low photo-current density which is traced to the formation of a current blocking ZnSe secondary phase at the front contact interface. The electron microscopy work has contributed to an understanding of the chemical stability of CZTS and has shown the need for an optimised back contact interface in order to avoid chemical decomposition reactions and formation of detrimental secondary phases. With this additional knowledge, a comprehensive picture of the material properties from the macroscopic down to the microscopic level can be attained throughout all required material layers.
132

Online ad hoc distributed traffic simulation with optimistic execution

Suh, Wonho 03 July 2012 (has links)
As roadside and in-vehicle sensors are deployed under the Connected Vehicle Research program (formerly known as Vehicle Infrastructure Integration initiative and Intellidrive), an increasing variety of traffic data is becoming available in real time. This real time traffic data is shared among vehicles and between vehicles and traffic management centers through wireless communication. This course of events creates an opportunity for mobile computing and online traffic simulations. However, online traffic simulations require faster than real time running speed with high simulation resolution, since the purpose of the simulations is to provide immediate future traffic forecast based on real time traffic data. However, simulating at high resolution is often too computationally intensive to process a large scale network on a single processor in real time. To mitigate this limitation an online ad hoc distributed simulation with optimistic execution is proposed in this study. The objective of this study is to develop an online traffic simulation system based on an ad hoc distributed simulation with optimistic execution. In this system, data collection, processing, and simulations are performed in a distributed fashion. Each individual simulator models the current traffic conditions of its local vicinity focusing only on its area of interest, without modeling other less relevant areas. Collectively, a central server coordinates the overall simulations with an optimistic execution technique and provides a predictive model of traffic conditions in large areas by combining simulations geographically spread over large areas. This distributed approach increases computing capacity of the entire system and speed of execution. The proposed model manages the distributed network, synchronizes the predictions among simulators, and resolves simulation output conflicts. Proper feedback allows each simulator to have accurate input data and eventually produce predictions close to reality. Such a system could provide both more up-to-date and robust predictions than that offered by centralized simulations within a single transportation management center. As these systems evolve, the online traffic predictions can be used in surface transportation management and travelers will benefit from more accurate and reliable traffic forecast.
133

Influence de la formulation sur les propriétés en fatigue d'élastomères industriels / Influence of the formulation on the fatigue properties of elastomeric materials

Masquelier, Isaure 03 December 2014 (has links)
Cette étude concerne l’influence de la formulation sur les propriétés en fatigue des élastomères. Pour cela, douze matériaux ont été préalablement choisis de façon à ce que leur formulation soit simplifiée mais représentative de celles de matériaux industriels. La première partie de l’étude vise la description des mécanismes et des scénarios d’endommagement par fatigue, pour différents matériaux, niveaux de sollicitation et pourcentages de durée de vie. Une vaste campagne d’essais de fatigue interrompus a été menée permettant une analyse statistique de la population de défauts. Ces données ont permis d’une part de proposer des scénarios de ruine pour les différents matériaux étudiés, et d’autre part d’identifier deux types de mécanismes d’amorçage autour d’inclusions de différentes natures. La deuxième partie de l’étude vise à comprendre les mécanismes d’amorçage de fissure de fatigue. Un protocole expérimental permettant d’obtenir les champs d’énergie dissipée directement à partir des champs de température mesurés a été mis en place. Ce protocole a d’abord été développé à une échelle macroscopique et validé grâce à des simulations par éléments finis. Il a ensuite été appliqué avec succès à l’échelle des inclusions pour des cas 2D. Enfin, la troisième partie de cette étude propose un critère énergétique basé sur un protocole d’auto-échauffement permettant une détermination rapide des propriétés en fatigue. L’approche proposée utilise un critère à deux paramètres et permet de prédire la courbe de Wöhler déterministe avec une seule éprouvette, en une demi-journée d’essai et uniquement à partir de mesures thermiques. Ce critère a été validé sur une large gamme d’élastomères, et s’avère capable de rendre compte de l’influence de la gomme, du taux et du type de charges. / This study deals with the influence of the formulation on the fatigue properties of elastomeric materials. Twelve materials have been chosen so that their formulations are simplified but representative of these used in the industry. The first part of the study aims to describe the fatigue damage mechanisms and scenarios, for different materials, strain levels and fatigue life durations. A large experimental campaign of interrupted fatigue tests has been performed enabling a statistical analysis of the defects population. On one hand, these data led to propose damage scenarios for the studied materials, and on the other hand, to identify two classes of initiation mechanisms around different nature of inclusions. The second part of this study aims to better understand the fatigue crack initiation mechanisms. An experimental protocol enabling to obtain directly the dissipated energy fields from the measurement of the temperature fields has been set up. This protocol has been first developed at the macroscopic scale and validated thanks to numerical simulations. Then, it has been applied successfully at the scale of inclusions for 2D cases. Finally, the third part of this study suggests an energetic criterion based on a heat build-up protocol leading a fast determination of the fatigue properties. This approach uses a criterion with two parameters and is able to predict the deterministic Wöhler curve with one sample, in half a day and thanks to thermal measurements only. This criterion has been validated on a wide range of elastomeric materials and is able to reflect the influence of the gum, the type and the amount of carbon black.
134

Produção de entropia e comportamento crítico em modelos irreversíveis com simetria C3v / Entropy production and critical behavior in irreversible models with C3v symmetry

Oscar Alberto Barbosa Bohorquez 11 May 2018 (has links)
A ênfase do trabalho recai na análise da taxa temporal de produção de entropia em sistemas de rede determinados por suas propriedades de simetria, no intuito de constituí-la como uma ferramenta paradigmática no estudo de sistemas irreversíveis. Nesse sentido, uma vez que se consegue consolidar uma definição consistente dessa grandeza para este campo, propõe-se uma abordagem estocástica para o modelamento da dinâmica dos exemplares considerados. O grupo de simetria C_ descreve as propriedades de invariância em sistemas com ampla relevância em física, de maneira que resulta natural elaborar a construção dos modelos em torno a sua estrutura, mais ainda quando se pode assumir que as características de simetria, no relativo à determinação da classe de universalidade dos modelos, são condições mais relevantes que a presença do não-equilíbrio, em coerência com a conjetura de Grinstein. Aliás, o modelo de Potts de três estados também apresenta propriedades de simetria próprias daquele grupo, além de ser passível de certo rigor no seu tratamento matemático, de maneira que oferece resultados consideravelmente satisfatórios e propícios para, por comparação, analisar os sistemas que concernem neste estudo. Assim, o procedimento tem como fim a determinação numérica da produção de entropia em sistemas com dinâmica irreversível e invariantes ante as transformações de simetria que compõem o grupo C_3v, partindo para isso de simulações de Monte Carlo em modelos estruturados sobre redes quadradas. A determinação da produção de entropia segue a prescrição de Schnakenberg (Schnakenberg [1976]), fundamentada nas correntes de probabilidade que surgem no sistema como consequência da violação da reversibilidade microscópica; a qual, por sua vez, estabelece a necessidade para os sistemas em equilíbrio de que todas as sequências cíclicas possíveis entre estados consecutivos sejam percorridas com igualdade de probabilidade num sentido quanto no inverso. Como uma segunda instância deste trabalho, também foram estudadas as propriedades de escalabilidade apresentadas por estos modelos durante seus primeiros instantes de evolução, isso, a partir da determinação numérica dos exponentes dinâmicos e sua caracterização dentro do marco teórico conhecido como \"short time scaling\'\' (Jansen et al. (1989)). Nesse sentido foram consideradas algumas das prescrições concernentes que tem apresentado melhor desempenho nos últimos anos. O observado mostra um comportamento coerente com a satisfação do que implicaria a conjetura de Grinstein para estes sistemas irreversíveis, indicando sua pertença à classe de universalidade do modelo de Potts de três estados, e, com isso, reafirmando os resultados obtidos em relação à produção de entropia. / This work is proposed as a study of the entropy production rate in lattice systems determined by its symmetries, looking for its consolidation as a paradigmatic tool in the area of irreversible and nonequilibrium systems. Henceforth, given the actual possibility of defining this quantity on that field, a stochastic perspective is adopted for modeling the dynamics of the considered systems. The C_ symmetry group describes the invariance properties of a wide range of physical systems, hence it results sensitive building the models to be dealt in accordance with its intrinsic characteristics, even more when it comes to be just fair, at the sight of the previous available analysis as well of the Grinstein conjecture, considering the invariance properties of systems as a more relevant factor than the reversibility conditions in what concerns the establishment of its universality class. The three states Potts model, indeed, shares its symmetry characteristics with those owned by the elements of the referred group and, also, concerning it there is a considerable amount of well confirmed information, becoming suitable for contrasting the results obtained. Henceforth, this work is focused on the numerical determination of the entropy production rate in irreversible systems whose invariance properties are the ones defined by the C_ symmetry group, implementing for that porpoise Monte Carlo simulations over square lattices models with the proper symmetries. By its own, the entropy production is determined in accordance with the Schnakenberg prescription (Scnhakenberg [1976]); deeply related with the probability currents emerging within irreversible systems as consequence of microscopic reversibility violation, which, in equilibrium, is imposed due to the mandatory equality between the evolution directions of all possible cyclic paths through a succession of states assumed by the system. As a second instance of this work, the scaling properties of the studied models during the first period of its evolution, just after the microscopic scale of time, were also analyzed. Henceforth, the determination of its dynamical exponents, as well as its characterization within the context of \"short time scaling\'\' (Jansent et al. [1989]) was realized through the calculus of some quantities with proven signatures of presenting an scalable \"initial slip\'\', finding strong suggestions for the models of being in the same universality class of the three state Potts model, fact coherent with the Grinstein conjecture if extended over them, but also with the observed behavior of the entropy production.
135

Pena de frango: estudo das características físicas das fibras têxteis / Chicken Feather: study of physical properties of textile fibers

Raquel Seawright Alonso 20 June 2013 (has links)
Baseando-se na possibilidade de inserção de um novo material de origem têxtil natural animal, bem como, a reciclagem de aproximadamente 1,175 milhões de toneladas descartadas anualmente da matéria-prima estudada (UBABEF, 2011), esta pesquisa teve como objetivo geral efetuar a caracterização física e microscópica de fibra de pena de frango para finalidade têxtil seja para o desenvolvimento de fios têxteis, não tecidos e reforço em compósitos ou outras aplicações. Deste modo, foram objetivos: i) realizar levantamento bibliográfico sobre estrutura e composição de penas e fibras de penas, reciclagem, aplicações existentes, técnicas e processos de caracterização da fibra; ii) coleta do material fibroso proveniente de um matadouro doméstico de frangos; iii) preparação do material, lavagem e secagem das penas; iv) testes mecânicos de caracterização como: alongamento, elasticidade e resistência realizados por meio do dinamômetro Instrom, determinação do teor de regain, umidade e densidade da fibra, bem como a taxa de encolhimento da fibra; v) testes microscópicos de caracterização como: microscopias longitudinais e transversais; vi) propostas e direcionamento do emprego das fibras caracterizadas para finalidade de produção têxtil. As principais conclusões foram: i) bibliografia inédita em português sobre penas de frango para a área têxtil; ii) estudo inédito no Brasil e na língua portuguesa de propriedades físicas e microscópicas de fibras de pena de frango; iii) com base em suas propriedades estruturais, perceberam-se características como brilho, conforto, maciez, toque, permeabilidade à líquido, leveza, entre outras propriedades, aumentando assim seu potencial de empregabilidade têxtil; iv) potencial de fiação e fabricação de têxteis para diversas aplicações. Publicações e palestras foram realizadas com os resultados desta dissertação. / Based on the possibility of developing a new textile material of natural animal origin, as well as the recycling of the studied raw material, of which approximately 1.175 million tons are annually discarded as waste in Brazil (UBABEF, 2011), this study aimed to characterize the general physical and microscopical fibers of chicken feathers for textile purpose for the development of textile yarn, non-woven and composite reinforcement. Its objectives were: i) to analyze the academic literature about the structure and composition of feathers and feather fibers, as well as its recycling, existing applications, processes and techniques of fiber characterization, ii) the collection of fibrous material from a chicken slaughterhouse, iii) the preparation of material, washing and drying the feathers, iv) to develop mechanical characterization tests such as elongation, elasticity and resistance made by Instrom dynamometer, determining the content, moisture regain and fiber density, v) to perform the microscopic characterization tests such as microscopy longitudinal and transverse, and vi ) to draft proposals on the employment of the analyzed and characterized fibers for purposes of producing textiles (yarns, reinforcement for composites, nonwoven blankets, etc.). The main findings were: i) unpublished literature in Portuguese about chicken feathers for the textile area, ii) unpublished study in Brazil and in portuguese language of physical and microscopic properties of chicken feathers\' fibers for the development of textile products of natural origin from such chicken feathers, iii) the identification of the potential for the production of blended yarn with cotton / wool, blankets and non-woven and reinforcement for composites, based on their physical, mechanical and microscopic properties, and, iv) the identification of the potential for yarn production (via spinning) and textile manufacturing for various applications. Publications and lectures were held with the results of this dissertation.
136

Emprego de estirpes de leptospiras isoladas no Brasil, na microtécnica de soroaglutinação microscópica aplicada ao diagnóstico da leptospirose em rebanhos bovinos de oito estados brasileiros / Use of strains of leptospires isolated in Brazil, for the microscopic agglutination test applied to the diagnosis of leptospirosis in bovine herds of eight Brazilian states

Anna Maria Casagrande Sarmento 22 January 2010 (has links)
A leptospirose bovina é uma das principais doenças reprodutivas que interfere diretamente nos índices de produção e produtividade da pecuária brasileira e mundial e por isso necessita de um aprimoramento do diagnóstico laboratorial. O objetivo do presente trabalho foi investigar a conveniência do emprego de estirpes de leptospiras autóctones isoladas no Brasil, na coleção de antígenos da microtécnica de soroaglutinação microscópica (SAM) aplicada a leptospirose. A coleção de antígenos de referência foi constituída pelos sorovares: Australis, Bratislava, Autumnalis, Butembo, Castellonis, Bataviae, Canicola, Whitcombi, Cynopteri, Grippotyphosa, Hebdomadis, Copenhageni, Icterohaemorrhagiae, Javanica, Panama, Pomona, Pyrogenes, Hardjo, Wolffi, Shermani, Tarassovi, Patoc e Sentot. As dez estirpes isoladas no Brasil incluíram os sorovares: Bananal (duas estirpes), Brasiliensis, Canicola (três estirpes), Copenhageni, Guaricura e Pomona (duas estirpes). Foram amostradas por conveniência, 109 propriedades e 9820 bovinos, fêmeas em idade de procriar, distribuídos em 84 municípios, dos Estados de: Goiás, Mato Grosso, Mato Grosso do Sul, Minas Gerais, Paraná, Rio Grande do Sul, Santa Catarina e São Paulo. Dos 9820 animais examinados, 5806 (59,12%) foram reagentes na SAM para qualquer sorovar com a coleção de 23 sorovares de referência. Com a coleção de antígenos de referência e dez estirpes autóctones houve 6400 (65,17%) reagentes, a diferença observada foi significante (p= 0,001). O único Estado em que não houve diferença significante no número de animais reatores para qualquer sorovar foi o de Santa Catarina (p=0,522). Das 109 propriedades trabalhadas, 106 foram consideradas positivas com pelo menos um animal reagente na SAM. Não houve diferença no número de propriedades positivas segundo a coleção de antígenos empregada. Os sorovares mais prováveis identificados com a coleção de antígenos de referência foram Hardjo (43,03 %), Shermani (20 %), Wolffi (9,96%), Grippothyphosa (5,42%) e Pomona (4,28%). Com a coleção ampliada por dez estirpes isoladas no Brasil, os sorovares mais prováveis foram Hardjo (31,00%), Guaricura - M4/84 (22,50%), Shermani (15,43%), Wolffi (4,76%), Grippothyphosa (3,71%) e Autumnalis (3,24%). O sorovar Guaricura, estirpe M4/84, isolada de bovinos e búfalos no Estado de São Paulo, foi o primeiro colocado como sorovar mais provável no Estado de Mato Grosso, diferença significante do valor obtido para o sorovar Hardjo (p= 0,0001). No Mato Grosso do Sul a despeito do valor absoluto ter sido superior para o sorovar Guaricura, a diferença observada com o sorovar Hardjo foi destituída de significado estatístico (p=.0,753). Em São Paulo o Guraricura foi o segundo colocado e em Minas Gerais Goiás ocupou a terceira posição. Esta mesma estirpe foi a mais provável em 27 propriedades das 109 trabalhadas (24,77%). A introdução de estirpes autóctones na coleção de antígenos da SAM propiciou a confirmação do diagnóstico de leptospirose em 594 animais (6,00%) classificados como não reagentes pela coleção de referência (p=0,001) / Bovine leptospirosis is one of the main reproductive diseases which interferes economically on the livestock and thus it is needed the amelioration of the laboratory diagnostic procedures. The aim of this work is to investigate the adequacy to use autochthonous strains of leptospires isolated in Brazil, added into the antigen collection applied for the microscopic agglutination test (MAT). The reference antigen collection was constituted by the following serovars: Australis, Bratislava, Autumnalis, Butembo, Castellonis, Bataviae, Canicola, Whitcombi, Cynopteri, Grippothyphosa, Hebdomadis, Copenhageni, Icterohaemorrhagiae, Javanica, Panama, Pomona, Pyrogenes, Hardjo, Wolffi, Shermani, Tarassovi, Patoc and Sentot. The ten strains isolated in Brazil included the serovars: Bananal (two strains), Brasiliensis, Canicola (three strains), Copenhageni, Guaricura and Pomona (two strains). By means of non-probability sampling, 109 farms and 9,820 bovines, females at reproductive age were chosen from the 84 municipalities of the states of Goiás, Mato Grosso, Mato Grosso do Sul, Minas Gerais, Paraná, Rio Grande do Sul, Santa Catarina e São Paulo . Among the 9,820 examined animals, 5,806 (59.12%) were reactants to the MAT for any serovar using the 23 reference serovars. Using the collection of reference serovars and the ten autochthonous strains there were 6,400 (65.24%) reactants, and the difference found was significant (p=0.001). The only state with non-significant results in the number of reactants for any serovar was the State of Santa Catarina (p=0.522). Of the 109 properties analyzed, 106 were considered positive at least with one reactant animal by MAT. According to the antigens used, there was no significant difference among the properties. The most probable serovars identified by the collection of reference antigens were Hardjo (43.03%), Shermani (20.00%), Wolfi (9.96%), Grippothyphosa (5.42%) and Pomona (4.28%). With the collection amplified with the ten strains isolated in Brazil, the most probable serovars were Hardjo (31.00%), Guaricura M4/84 (22.50%), Shermani (15.43%), Wolffi (4.76%), Grippothyphosa (3.71%) and Autumnalis (3.24%). The serovar Guaricura, strain M4/84, isolated from bovines and buffaloes in the State of São Paulo, was ranked at the first place as the most probable serovar in the State of Mato Grosso and Mato Grosso do Sul, but the differences observed with the serovar Hardjo were significant only in Mato Grosso (p=0,0001). In São Paulo State, the Guaricura serovar was the second most probable and in the states of Minas Gerais and Goiás the third one. This same strain was the most probable in 27 properties among the 109 examined (24.77%). The addition of autochthonous strains into the MAT antigen collection provided the confirmation of the diagnosis of leptospirosis in 594 animals (6.00%) which have been classified as non-reactants by the reference collection
137

Análise morfológica da superfície de interface epitélio-tecido conjuntivo da face dorsal da língua de cetáceos (ordem Cetacea subordem Odontoceti), empregando os métodos de microscopia de luz e eletrônica de varredura / Morphologic analysis of the interface epithelium-connective tissue surface of the dorsal face of the cetaceans tongue (order cetacea sub-order odontoceti), using the light and scanning electron microscopic methods

Juliana Plácido Guimarães 17 March 2006 (has links)
A ordem Cetacea compreende golfinhos e baleias, mamíferos totalmente adaptados ao ambiente aquático. A língua de duas espécies de cetáceos, Pontoporia blainvillei e Sotalia fluviatilis, foram utilizadas para descrição da morfologia das papilas linguais e da superfície de interface epitélio-tecido conjuntivo da lâmina própria, empregando as técnicas de microscopia de luz e eletrônica de varredura. As línguas foram fixadas e divididas em três porções: rostral, médio e caudal e processadas conforme os protocolos das técnicas utilizadas. A língua da Pontoporia blainvillei e Sotalia fluviatilis estava revestida por um epitélio estratificado queratinizado, sendo possível observar as camadas basal, espinhosa, granulosa e córnea. Pode-se notar que na língua, o tecido conjuntivo denso apresentava vasos sanguíneos e profundamente relacionado com o tecido muscular. A superfície de interface epitélio-tecido conjuntivo da lâmina própria apresentou papilas conjuntivas de várias formas. Elas correspondem às papilas filiformes e valadas, mostrando feixes de fibras colágenas em disposição original. Na microscopia de luz polarizada revelou-se fibras colágenas do tipo I e III. No terço médio e caudal de ambas as espécies foram encontradas ácinos de glândulas salivares. As amostras tratadas com solução de hidróxido de sódio, tiveram a camada epitelial removida, e as papilas conjuntivas foram observadas em aspecto tridimensional. Foi possível observar que a superfície dorsal de ambas as espécies é totalmente recoberta por papilas conjuntivas de aspecto filiforme. Observa-se também a presença dos forames dos ductos das glândulas salivares nas porções média e caudal da língua, sendo eles mais numerosos nos filhotes. Morfometricamente, as papilas conjuntivas apresentaram maior comprimento na espécie Sotalia fluviatilis do que na Pontoporia blainville. Foi observado somente na espécie Pontoporia blainvillei estruturas conjuntivas arredondadas na região média e caudal. Embora as áreas dessas estruturas tenham sido maiores na região caudal que na média, estatisticamente estes resultados não foram significativos (P>0,05). / The Cetacea order comprises dolphins and whales, mammals totally adapted to the aquatic ambient. The tongue of two cetaceans species, Pontoporia blainvillei and Sotalia fluviatilis, was studied for description of the morphology of the lingual papillae and of interface epithelium the connective tissue surface, using the light and scanning electron microscopic techniques. The tongues were fixed and divided in three portions: rostral, medium and caudal and treated according to the protocols of techniques used. The tongues of the Pontoporia blainvillei and Sotalia fluviatilis were covered by keratinized stratified epithelium, being that is possible to verify the basal, spinosa, granular and cornetiel ayers. In the tongue the dense connective tissue of lamina propria showed blood vessels and muscular layer was deeply related. The interface epithelium-connective tissue surface of the lamina propria presented connective tissue papillae which are various in shape. They correspond to the filiform and vallate papillae showing the collagen fibers bunches in original disposition. In the polarized light microscopy revealed collagen fibers type I and III. In the medium and caudal third of both species various groupins of salivary gland acini. The samples treated with sodium hydroxide solution, the epithelial layer was removed and the connective tissue papillae were observed in three-dimensional SEM images. It was possible to observe that the dorsal surface of the both species is totally covered by connective tissue papillae of filiform aspect. We observed also the presence of the ducts of the salivary glands in the media and caudal portions of the tongue, being them more numerous in pups. Morphometric analysis showed that the connective tissue papillae presented larger length in the Sotalia fluviatilis than in the Pontoporia blainville samples. The round connectives structures in the media and caudal portions were observed only the Pontoporia blainvillei species. Although, the areas of those structures have been major in the caudal region than media, and these results were not signifficant (P>0,05).
138

Évaluation de la Durabilité des Enrobés Chauds et Tièdes Contenant des Agrégats d’Enrobés / Evaluation of the Durability of Hot and Warm Mix Asphalt Containing Recycled Asphalt Pavement

De mesquita lopes, Manuela 09 March 2015 (has links)
Le recyclage des enrobés bitumineux fabriqués selon un procédé tiède répond aux exigences du développement durable: il limite l'apport de matériaux neufs, permet la gestion des déchets et réduit la consommation d'énergie. Le recyclage des enrobés date des années 70 ; ce qui a changé depuis, c'est la volonté de pérenniser le recyclage à fort taux, définit ici à plus de 25% d'agrégats d'enrobés (AE). Les AE contiennent une part de bitume qui est valorisable pour ses propriétés viscoélastiques de liant hydrocarboné. Il est ainsi recherché une mobilisation de ce liant vieilli dans le processus de recyclage. L'un des problèmes suspectés lors du couplage recyclage/procédé tiède est le phénomène de double enrobage pouvant impacter la rhéologie du nouveau matériau: le liant de l'AE et le liant d'apport ne se mélangeraient pas totalement du fait de l'abaissement des températures de fabrication et formeraient des couches superposées. Ce phénomène serait la cause de dysfonctionnements mécaniques au niveau de l'enrobé. Il se pose donc la question de la qualité de l'enrobage de surfaces granulaires déjà enrobées et du manque de moyens de caractérisation pour l'observation in situ de l'interface. Dans ce travail de thèse, la qualité d'enrobage des agrégats d'enrobés par un liant d'apport a été évaluée à l'échelle microscopique et macroscopique. Au niveau microscopique, il a été proposé d'utiliser un outil de micro-spectroscopie infrarouge pour évaluer in situ la qualité d'interface entre l'AE et le liant d'apport et suivre la répartition spatiale de ces deux composants au sein d'enrobés de laboratoire. Cela a nécessité un important développement expérimental afin de pouvoir appliquer un accessoire d'imagerie infrarouge aux mélanges complexes que sont les formules d'enrobés bitumineux constitués de différentes fractions granulaires et de liant bitumineux. Il a ainsi été possible, grâce à l'identification préalable de traceurs internes, de suivre la remobilisation partielle du liant vieilli de l'AE. En parallèle, au niveau macroscopique, un protocole d'essai a été développé afin d'évaluer la durabilité des enrobés contenant des forts taux d'AE (50%), notamment des enrobés fabriqués selon un procédé tiède. L'essai actuel de fatigue est l'un des essais qui permet le mieux d'évaluer la durée de vie d'une couche de chaussée. Mais cet essai accéléré est biaisé car le bitume des échantillons testés n'a pas eu le temps de vieillir comme c'est le cas sur une vraie chaussée. Dans ce travail, il a donc été proposé d'ajouter une étape de vieillissement du matériau avant les essais de fatigue, d'orniérage, de tenue à l'eau et de module complexe. Il est supposé que le comportement réel du matériau se situerait entre celui du matériau non vieilli et celui du matériau vieilli. Les principaux résultats obtenus montrent qu'un enrobé tiède contenant un taux élevé d'AE présente de bonnes performances mécaniques excepté qu'il a tendance à être plus sensible à la fatigue qu'une même formulation de matériau fabriqué à chaud ou selon un procédé tiède mais sans ajout AE. / The recycling of asphalt mixtures manufactured with a warm process meets the requirements of sustainable development: it limits the use of new materials, allows waste management and reduces energy consumption. The recycling of asphalt mixtures dates from the 70's. What has changed since that is the will to sustain high rate recycling, defined here by more than 25% of Reclaimed Asphalt Pavement (RAP). RAP contains a part of bitumen that is recoverable for its viscoelastic properties of asphalt binder. It is thus desired to mobilize this aged binder in the recycling process. One of the suspected problems when coupling recycling and warm process is the phenomenon of double coating that could affect rheological properties of the new material: the RAP binder and the new binder do not would mix completely due to the reduction of processing temperatures and would form superimposed layers. This phenomenon would cause mechanical dysfunctions in the asphalt mixture. This raises the question of the quality of the coating of granular surfaces, previously coated, and lack of characterization tools for in situ observation of the interface. In this thesis work, the quality of coating of RAP by a new binder has been evaluated at the microscopic and macroscopic scales. At the microscopic level, it has been proposed to use infrared micro-spectroscopy tool to evaluate the quality of interface between the RAP and the new binder and to follow the spatial distribution of these two components within mixtures produced in laboratory. To do that, it has been necessary to carry out an important experimental development in order to apply an infrared imaging accessory to complex mixtures that are the bituminous mixtures made of different granular fractions and bituminous binder. It was then possible, based on previous identification of internal tracers, to follow the partial remobilization of RAP aging binder. In parallel, at the macroscopic level, a testing protocol has been developed to evaluate the durability of high rate recycled asphalt mixtures (50% of RAP), including mixes produced in a warm process. The current fatigue test is one of the tests that best evaluate the lifetime of a pavement layer. But this accelerated test is biased because the bitumen of the mixtures tested did not have time to aged, as occurs in the case on a real road. In this work, it was proposed to add an aging step of the material before fatigue test, rutting test, modulus test and moisture damage test. It is assumed that the real behavior of the material would range between that of the unaged material and that of aged material. The main obtained results show that warm mixture asphalt containing high rate of RAP exhibit good mechanical performance, with a trend to be more susceptible to fatigue than a similar hot mixture or a warm mixture without added RAP.
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Développement de contreplaqués pour la construction navale : caractérisation multiéchelle et compréhension des phénomènes de collage du pin maritime à l'état vert / Plywood manufacture for the shipbuilding industry : multi-scale characterisation and understanding of wet maritime pine adhesion phenomena

Lavalette, Anne 04 December 2013 (has links)
L’objectif de cette thèse est de développer des panneaux de contreplaqué collés à l’état vert à destination des coques et de l'agencement de bateaux. La technologie du moulage sous vide est choisie pour former des panneaux constitués de plis de pin Maritime déroulés non séchés et collés à l'aide d'un adhésif polyuréthane. Une étude approfondie été réalisée dans le but de fixer les paramètres de collage permettant aux contreplaqués de répondre aux exigences requises dans la construction navale. L’influence des paramètres de fabrication du panneau sur ses propriétés mécaniques est déterminée à partir d’un plan d'expériences. La teneur en eau et le grammage d'adhésif appliqué sont particulièrement étudiés. Le comportement mécanique des différents échantillons de contreplaqué a été caractérisé grâce à des tests normalisés de cisaillement et des tests de flexion. Des mesures de mouillabilité ainsi que des observations microscopiques des joints ont permis de mieux comprendre les résultats mécaniques, et d'expliquer les phénomènes physico-chimiques mis en jeu. Le matériau retenu à partir de cette étude est mis en œuvre dans un démonstrateur, pour validation du procédé utilisé. / The subject of this work is the manufacturing of green-glued plywood panels for the interior and the plating of a ship. The vacuum-moulding process is chosen to produce panels by assembling maritime pine veneers in the wet state with polyurethane adhesive. A study has been done to fix the parameters for gluing so that the manufactured plywood can answer to the mechanical characteristics required by the shipbuilding sector. The effect of several gluing parameters on the panel's mechanical properties is determined by an experimental design method. The wood moisture content when gluing and the amount of adhesive applied are mainly studied. The plywood panels' mechanical characterisations are realised using standardised shear tests and bending tests. In addition to the mechanical tests, wettability measures and bond lines microscopic observations provide a better understanding of the physic-chemical phenomena of green wood gluing. The material defined in this study is implemented in a boat hull prototype.
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Propriétés physico-chimiques des carbonates fondus par simulations atomistiques / Physico-chemical properties of molten carbonates from atomistic simulations

Desmaele, Elsa 13 October 2017 (has links)
L’étude des carbonates fondus présente un enjeu double : fondamental et appliqué. La description systématique de leurs propriétés physico-chimiques sur des gammes étendues de conditions thermodynamiques et de compositions chimiques est important pour le développement de leurs applications technologiques, ainsi que pour la compréhension de certains processus géochimiques. Afin de modéliser les carbonates fondus par simulations atomistiques, nous avons développé un champ de force classique en nous basant sur les données expérimentales disponibles dans la littérature et sur les structures microscopiques issues de simulations de dynamique moléculaire ab initio que nous avons réalisées. En utilisant ce champ de force dans des simulations de dynamique moléculaire, nous avons évalué les propriétés thermodynamiques (équation d’état, tension de surface à pression atmosphérique), la structure microscopique du liquide et les propriétés de transport (coefficients de diffusion, conductivité électrique, viscosité) d’un ensemble de carbonates fondus (Li2CO3, Na2 CO3 , K2 CO3, MgCO3 , CaCO3 et nombre de leurs mélanges) de leur point de fusion jusqu’aux conditions thermodynamiques du manteau terrestre. Nos résultats sont en très bon accord avec les données de la littérature. À notre connaissance, un modèle moléculaire des carbonates fondus couvrant un aussi large domaine de conditions thermodynamiques, de compositions chimiques et de propriétés physico-chimiques n’a encore jamais été publié. Sur la base de ce modèle, nous discutons aussi quelques propriétés des carbonates fondus à l’interface avec une phase gazeuse (gaz rares) : tension de surface et solubilité du gaz. / Because of their remarkable physicochemical properties carbonate melts receive an increasing interest in both fundamental and applied fields. Having a clear picture of their properties over a large range of thermodynamic conditions and chemical compositions is important for developing technological devices (e.g. fuel cell technology) and for providing a better understanding of a number of geochemical processes (e.g. role of molten carbonates in the geodynamics of the Earth’s mantle). To model molten carbonates by atomistic simulations, we have developed an optimized clas- sical force field based on experimental data available in the litterature and liquid structure data obtained from ab initio molecular dynamics simulations that we have performed. In implementing this force field into a molecular dynamics simulation code, we have evaluated the thermodynamics (equation of state, surface tension at atmospheric pressure), the microscopic liquid structure and the transport properties (diffusion coefficients, electrical conductivity and viscosity) of a set of molten carbonates (Li2CO3 , Na2 CO3, K2 CO3 , MgCO3, CaCO3 and many of their mixtures) from their melting point to the thermodynamic conditions of the Earth’s upper mantle. Our results are in very good agreement with the data available in the literature. To our knowledge a molecular model for molten carbonates covering such a large domain of thermodynamic conditions, chemical compositions and physico-chemical properties has never been published yet. Based on this model we also discuss some results on molten carbonates at the interface with a vapor phase (noble gases) : surface tension and gas solubility.

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