Esta dissertação teve como objetivo o estudo de modelos para séries temporais bivariadas, que tem a estrutura de dependência determinada por meio de funções de cópulas. A vantagem desta abordagem é que as cópulas fornecem uma descrição completa da estrutura de dependência. Em termos de inferência, foi adotada uma abordagem Bayesiana com utilização dos métodos de Monte Carlo via cadeias de Markov (MCMC). Primeiramente, um estudo de simulações foi realizado para verificar como os seguintes fatores, tamanho das séries e variações nas funções de cópula, nas distribuições marginais, nos valores do parâmetro de cópula e nos métodos de estimação, influenciam a taxa de seleção de modelos segundo os critérios EAIC, EBIC e DIC. Posteriormente, foram realizadas aplicações a dados reais dos modelos com estrutura de dependência estática e variante no tempo / The aim of this work was to study models for bivariate time series, where the dependence structure among the series is modeled by copulas. The advantage of this approach is that copulas provide a complete description of dependence structure. In terms of inference was adopted the Bayesian approach with utilization of Markov chain Monte Carlo (MCMC) methods. First, a simulation study was performed to verify how the factors, length of the series and variations on copula functions, on marginal distributions, on copula parameter value and on estimation methods, may affect models selection rate given by EAIC, EBIC and DIC criteria. After that, we applied the models with static and time-varying dependence structure to real data

Les avancées scientifiques dans les plantes, les technologies de transformation, les biotechnologies permettent d’envisager à terme que des produits de la chimie verte du carbone renouvelable, substituables et compétitifs, remplaceront ceux issus des matières fossiles. En effet, l’un des grands thèmes de recherche actuelle en chimie est la chimie dite "propre". Dans ce cadre, le projet proposé vise une double valorisation de déchets issus de la filière "bois". La première valorisation concerne l’isolation de molécules extractibles, qui sont présentes en très faible quantité dans les matériaux lignocellulosiques, donc des produits à forte valeur ajoutée. La seconde valorisation concerne la transformation du résidu, après isolation des extractibles, en charbon actif, autre matériau à forte valeur ajoutée. Le procédé proposé concerne donc le secteur de la « chimie verte » avec une approche intégrée de « valorisation des déchets ». Nous avons utilisé comme matière première des déchets de pin maritime des Landes sous forme de sciure, à partir desquels nous avons extrait les composés volatils à partir de différents procédés intensifiés tels que les microondes et les ultrasons. L’huile obtenue a été caractérisée en déterminant sa quantité (rendement), sa composition, sa capacité antioxydante, la quantité en polyphénols qu’elle renferme, sa microstructure, etc. Afin que la valorisation de ces déchets soit totale, les résidus solides ont subi une pyro-activation physique avec du CO2 et de la vapeur d’eau comme agents activants pour produire du charbon actif. Une optimisation a été effectuée à partir des réponses suivantes : la surface BET, la taille des pores par adsorption d’azote à 77 K et les propriétés d’adsorption du charbon actif en phase aqueuse (paramètres de Langmuir et Freundlich). / The scientific advances in plants, processing technologies, biotechnology allow considering that the products of renewable carbon green chemistry, substitutable and competitive will replace the products issued from fossil material. In this framework, this project concerned a double valorization of waste from wood sector. The first valorization concerned the isolation of extractable compounds which are present in low quantities and could be considered as a high added value product. The second valorization deals with the transformation of the residue in another high added value product : the activated carbons. Thus, the proposed process concerns the sector of "green chemistry" with an integrated approach of "waste valorization". In the framework of this study, we used as raw material sawdust of maritime pine (pinus pinaster) from Landes area from an isolation of volatiles extracted by some intensified processes such as microwave and ultrasounds. The obtained oil was characterized by determining the quantity (yield), the composition, the antioxidant capacity, the polyphenols content and by studying the microstructure. To achieve a total valorization the residues were submitted to a pyro-activation with CO2 and water vapor as activating agents to produce an activated carbon. An optimization was carried out according to different responses as the BET surface, the pores size by nitrogen adsorption at 77 K and the adsorption properties of activated carbon in aqueous phase (Langmuir et Freundlich parameters).

La modification de la structure des matériaux par Détente Instantanée Contrôlée (DIC), implique nécessairement un processus d’autovaporisation instantanée en conditions thermodynamiques extrêmes de surchauffe du liquide. Les divers processus DIC de modification de la structure par expansion contrôlée, d’extraction et de refroidissement instantané sont d’un intérêt particulier. Les conditions opératoires et les caractéristiques spécifiques du produit interagissent mutuellement pour aboutir au meilleur résultat, principalement en termes de texture. Les modifications des caractéristiques structurelles généralement traduites par des taux d’expansion du produit, dépendent donc des conditions opératoires et des propriétés thermiques et rhéologiques de la matière. De nombreuses études initiales ont montré l’intérêt de déterminer l’évolution des divers processus à travers un suivi et un enregistrement instantané des images, des températures et de la pression à l’échelle de 1000 unités par seconde ; il a ainsi été indispensable de mettre en opération une caméra ultra rapide à 1000 images / s, des capteurs de température et de pression à temps de réponse de l’ordre du ms, placés dans le réacteur et au sein du produit. Une analyse fondamentale a prouvé l’importance de la thermodynamique, du transfert et de la problématique d’expansion pendant le traitement. L’analyse des expériences est réalisée par la détermination des taux d’expansion, surfacique et volumique, de la durée du processus d’expansion proprement dite, de l’analyse des caractéristiques micro-structurelles par MEB, mais principalement par la détermination de la température de transition vitreuse, de la différence de température minimale et d’ébullition, et du taux d’échange de chaleur. Plusieurs produits ont été étudiés (fromage, tofu, pomme, pomme de terre, carotte et banane). Des essais préliminaires adéquats ont permis d’identifier les domaines de variation des paramètres opératoires et d’adopter la méthode des plans d’expériences rota tables à cinq niveaux pour quantifier les diverses réponses nécessaires. / The structural modification of materials by the process of instant controlled pressure drop (DIC), is mainly based on the instant autovaporization process in very far from thermodynamic equilibrium conditions. The structure modification process and the volume evolution strictly depend on DIC operational parameters and the product characteristics mutually interacting to achieve the objective in terms of texture.The change in the structural characteristics of the product is generally revealed through the expansion rates of the product ; it depends on the operating conditions. This study will use a snapshot taken by a high speed video camera 1000 fps, coupled with 1 ms response temperature and pressure sensors, placed in the treatment vessel and inside the product. A fundamental analysis has proved the importance of thermodynamics, the transfer and the specific problematic of expansion during treatment. Study was carried out by determining the3D expansion ratio, the 2D surface expansion ratio, and the volumetric expansion ratio, as well as the durations of expansion just after pressure drops, the analysis of SEM micro-structural characteristics, the different glass transition temperatures Tg, the differences between lowest product and reactor temperatures and boiling temperature, and the heat exchange rate. Various products were considered (cheese, tofu, apple, potato, carrot and banana). The preliminary tests with each have led us to identify the relevant operating parameter ranges. Different fundamental conclusions and industrial application could be thus defined.

The thesis is about deformation measurement of the nozzle ring in variable nozzle turbine mechanism under temperature load. In the first part, there is a brief description of the turbocharger. In the second part, methods of deformation measurement are mentioned there. The main part of the thesis includes component testing of selected measuring methods and their application for measuring deformation of the nozzle ring on the turbocharger. Test is done on a gas stand which simulates the thermal load conditions of the turbocharger, same which is exposed to on the engine.

Cette thèse s'intéresse à l'amélioration de la prévision de l'éclatement des pièces tournantes des turbomachines. L'axe de recherche principal a été celui de l'identification du comportement du matériau jusqu'à rupture pour des sollicitations multi-axiales représentatives et l'identification des conditions de rupture locale elles mêmes. Pour cela une approche basée sur la corrélation d'image numérique intégrée a été suivie. L'autre axe abordé dans cette thèse a été celui de la prévision objective et robuste de la rupture par la mécanique de l'endommagement dans le cadre de simulations explicites utilisant des techniques de scaling pour diminuer les temps de calcul. Deux matériaux ont été étudiés, un alliage titane TA6V et un alliage nickel Udimet 500. Des éprouvettes ont été définies pour permettre d'avoir des sollicitations proches de celles en service et pour permettre d'utiliser des techniques de mesure de champs. Un code commercial (ABAQUS) est utilisé dans une approche intégrée de la corrélation des images numériques (CIN). Le principe de ces méthodes est d'optimiser la corrélation directement à partir des paramètres du modèle sans passer par une procédure intermédiaire demandant de reconstruire préalablement les champs de déformations. Cette technique, qui peut-être vu comme très régularisante, confère à la méthode une grande robustesse, ce qui permet d'obtenir des informations même en présence de mouchetis dégradés lors des phases ultimes de chargement. L'ensemble des paramètres constitutifs des modèles peut alors être identifié avec un seul essai hétérogène. Dans l'étude un accent particulier a été mis sur l'analyse des champs de triaxialité, dont l'importance sur les conditions de rupture est suspectée, en utilisant des éprouvettes fines et des éprouvettes épaisses. Des lois de comportement ont pu être identifié pour des niveaux de déformations plastiques jusqu'à 3 fois supérieurs à ceux atteints dans des essais de traction uni-axiaux et ceci en présence d'adoucissement global. L'intégration étroite des essais et des simulations a également permis d'analyser l'état de déformation et contraintes des éléments proches de la surface de rupture juste avant celle-ci et ainsi de tester des critères de rupture potentiels avec un grand nombre de données. Pour la seconde partie de la thèse, plus exploratoire faute de temps, une étude préliminaire a porté sur la possibilité d'utiliser des modèles à taux d'endommagement limités combinés avec des techniques de scaling pour utiliser des simulations explicites dans le cadre de sollicitations centrifuges quasi-statiques. Les premiers résultats montrent qu'une accélération est possible avec des niveaux d'erreurs relativement bas sur les vitesses de rotation conduisant à la rupture et ceci dans des temps comparables avec des simulations implicites quasi-statique, l'avantage étant la robustesse des analyses en dynamique explicite. / This thesis addresses the amelioration of the burst prediction of turbo-engines rotating parts.The principal axis of this study was the identification of the material behaviour up fracture under multi-axial loading and the identification of the local condition at failure. To accomplish this, an integrated digital image correlation approach was employed.The other thematic axis of this thesis was the objective and robust prediction of rupture using the damage mechanics in the framework of explicit simulations and the study of the influence, on the prediction, of various scaling techniques used to decrease the computation time.Two materials were studied, the titanium alloy TA6V and the nickel alloy Udimet 500. The samples were defined to guarantee similar loading conditions as those in the disks in service and to allow the use of field measurement techniques.A commercial code (ABAQUS) is used in an integrated approach to Digital Image Correlation (DIC). The principle of this method is to optimize the correlation of the test directly with the model parameters without passing by an intermediate procedure requiring the reconstruction of the deformation field beforehand. This technique, which can be seen as highly regularising, grants a considerable robustness to the method, which allows obtaining information from degraded speckle patterns encountered at the end of the test. The entire set of constitutive parameters can be identified with only one heterogeneous test. Within this study, a particular accent was laid on the analysis of triaxiality fields by using thin and thick samples. The importance of these fields for the fracture conditions is suspected.Constitutive models were identified for plastic strains that were about three times higher than the ones achievable in uniaxial tensile test on smooth sample.The close integration of the experiments and simulations allowed the analysis of deformation and stresses of the elements near the failure surface at the instant just before failure. This allowed the testing of different criteria with a large amount of data.For the second axis of the thesis, preliminary studies examined the possibility to use limited damage rate models combined with scaling techniques. These latter allow performing explicit simulations in context of a centrifugal quasi-static loading. The results show that acceleration is possible. The errors of the rotational speeds, which lead to disk fracture, are relatively low. The simulation times are comparable to implicit quasi-static simulations, while the main advantage is the maintained robustness in explicit simulations.

No description available.

The fracture of water ballast tank (WBT) coatings due to thermal stresses is widely recognised as an issue. Upon coating fracture, rapid corrosion of the tanker steel structure will occur, leading to expensive structure repairs or even tanker scrapping. In this project, the fracture behaviour of two experimental WBT coatings, referred to as A and B, in the forms of free film and substrated coatings was investigated. Static tensile tests and fatigue tests of the substrated coatings were performed. A finite element model of coating cracking was developed. Thermal stress and J-integral of surface cracking defects in substrated coatings were calculated using the model, in which the effects of defect size, coating thickness, and thermal strain on coating fracture were investigated. For the first time, fracture mechanics was used to explain WBT coating fracture behaviour. The J-integral of surface defects was used to predict the onset strain of coating cracking under mechanical strains in laboratory and under thermal strains in service. A theoretical comparison between the cracking drive forces in terms of J - integrals in WBT coatings under thermal strains and mechanical strains was performed.

Traumatic brain injury (TBI) is a major cause of death among trauma patients and is associated with a high rate of mortality due to complications such as bacterial pneumonia, sepsis, and subsequent coagulopathies. While severe TBI is positively associated with the development of pneumonia, mild traumatic brain injury (mTBI) results in a paradoxical decrease in mortality following bacterial pneumonia via an unidentified mechanism. New evidence suggests that mTBI stimulates vagus nerve signaling resulting in an anti-inflammatory state that is mediated by neurotransmitters (NT) such as acetylcholine (ACh) and substance P (Sub P). This anti-inflammatory state induced by mTBI has been correlated with an increased resistance to pneumonia (PNA) in mice and has been shown to be mediated in part by increased bacterial clearance in the lungs via enhanced neutrophil recruitment. However, it has not been investigated whether this reduced mortality is due to alterations in the coagulation system and if they have any effect on either the severity or occurrence of disseminated intravascular coagulation (DIC), a common sequelae of pneumonia-induced sepsis. Our study investigates whether administration of mTBI prior to pneumonia challenge in mice decreases mortality by ameliorating DIC. We assess and define DIC in our mouse models by changes in plasma coagulation parameters including fibrinogen, D-dimer, and plasminogen activator inhibitor-1 (PAI-1) Our study found that mTBI administration prior to pneumonia significantly decreased mortality in mice gavaged with high concentrations of Pseudomonas aeruginosa (Psd.). We also found that mTBI administration prior to pneumonia rescued fibrinogen levels and increased D-dimer levels in plasma, suggesting a compensated fibrinolytic state and amelioration of DIC. Circulating neutrophil and absolute leukocyte counts were also increased in mTBI/pneumonia models compared to those with pneumonia alone, supporting previous evidence implicating mTBI as the origin of enhanced bacterial clearance in lungs. Taken together, these data suggest that the increase in survival seen in patients with mTBI is in part due to alterations in coagulation.

Abstract The Penghu Channel (PHC), situated in the southeastern Taiwan Strait (TS), is the major conduit for the South China Sea water (SCSW) and Kuroshio subsurface water flowing into the TS. However, the previous studies in this area were largely focused on the aspects of physical oceanography, with scant attention to the chemical hydrography is poorly studied, and therefore little understood. In order to better understand the seasonal variations of chemical hydrography in the southern PHC, we conducted a systematic survey of chemical hydrography aboard R/V Ocean Research III during cruises in January, March, July and October 2001 as well as March 2002. The water above 200m in the southern PHC is characteristic of salinity and temperature between those of SCSW and Kuroshio water (KW), suggesting it is mixing between these two waters. Nonetheless, the salinity and temperature below 200m are dominated by the SCSW. The relative amount of SCSW and KW flowing into the PHC has varied seasonally and annually. During the transition period of monsoon, KW was more than SCSW, but SCSW had a larger quantity during the northeast and southwest monsoon. The slope of the regression line between the d13CDIC and PO4-3 (0-100m, -0.55; below 100m, -0.30) indicates that the distributions of d13CDIC and PO4-3 in the study area may be controlled by the effect of air-sea exchange or the mixing of different water masses or both. In addition, to evaluate the overall error in d13CDIC analysis, we have checked carefully whether the different storage bottles, the various duration of storage, and different amount of saturated HgCl2 solution added in the water samples would produce uncertainty on the d13CDIC analysis. Our results show no significant discrepancy among these the different treatments, suggesting that the water samples can be stored without measurable d13CDIC change at least for 3 months.

The Gram-negative bacterium Legionella pneumophila is an intracellular parasite of aquatic protozoa. It exhibits a distinct dimorphic lifecycle that alternates between vegetative replicative form (RF) and infectious cyst-like form (CLF). Inadvertent inhalation of aerosolized CLFs by immunocompromised individuals leads to an infection in alveolar macrophages causing Legionnaires' disease. To further study a Legionella infection the use of the multicellular organism Caenorhabditis elegans was done. Differential Interference Contrast (DIC) microscopy of live L. pneumophila infected nematodes shows Legionella-containing vacuoles (LCVs) with motile forms. Transmission Electron Microscopy (TEM) defined the ultrastructure of L. pneumophila forms found in the primary infection site of the intestinal lumen and the secondary infection site in the gonadal tissues. These findings suggest the possible intracellular replication cycle of Legionella occurring in the gonadal tissues of the nematode. Providing insight and a plausible evolutionary origin of the ability of L. pneumophila to manipulate the macrophage innate immune system. / October 2014