Teses / dissertações sobre o tema "Cyclage mécanique"
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Goupillaud, Isabelle. "Comparaison des endommagements matriciels par fatigue mécanique et par cyclage thermique de composites structuraux : caractérisation et modélisation". Poitiers, 1998. http://www.theses.fr/1998POIT2332.
Texto completo da fonteBouarroudj-Berkani, Mounira. "Etude de la fatigue thermo-mécanique de modules électroniques de puissance en ambiance de températures élevées pour des applications de traction de véhicules électriques et hybrides". Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2008. http://tel.archives-ouvertes.fr/tel-00346572.
Texto completo da fonteAinsi, la première partie de cette thèse présente les tests expérimentaux réalisés en cyclage actif durant lesquels nous avons cherché à évaluer la tenue des modules IGBT (600V-200A) fonctionnant à différentes températures ambiantes (température de semelle) et différentes températures de jonction (température des puces). Afin de chercher à comprendre les mécanismes physiques mis en jeu dans la dégradation de l'assemblage, les essais ont été arrêtés rapidement dès lors qu'un indicateur de défaillance laissait supposer une initiation de processus de dégradation.
Dans la deuxième partie, nous nous sommes focalisés sur la tenue des brasures substrat/semelle dans des conditions de cycles thermiques passifs. Sachant qu'habituellement le facteur d'accélération retenu pour le vieillissement de ces brasures est l'amplitude des cycles thermiques, nous avons cherché dans cette partie à évaluer non seulement l'effet de l'amplitude des cycles thermiques mais aussi les niveaux des paliers haut et bas sur l'initiation des fissures dans ces brasures et leurs propagation au cours du cyclage.
Enfin, pour comprendre et analyser le comportement de la brasure et de l'assemblage sous les contraintes de cycles thermiques, une étude par simulation numérique est présentée dans la dernière partie. Une étude numérique effectuée sous des conditions de température similaires à celles imposées dans la partie expérimentale a permis de localiser et d'évaluer les contraintes thermomécaniques que subissent les éléments de l'assemblage. Surtout, nous donnons des éléments de réponse permettant d'établir un lien entre les paramètres thermiques du cyclage passif et les grandeurs physiques qui sont influent sur la durée de vie des brasures. Enfin, cette partie se termine sur une étude numérique dans laquelle nous avons cherché à simuler l'effet combiné des cyclages actifs et passifs sur les contraintes mécaniques au sein des modules IGBT afin de rendre compte des contraintes imposées aux modules dans une application réelle.
Tantchou, Yakam Guy. "Modélisation en cyclage-fluage du comportement mécanique d'un liner thermoplastique collapsé utilisé dans les réservoirs de stockage d'hydrogène gazeux". Thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2017. http://www.theses.fr/2017ESMA0018/document.
Texto completo da fonteHyperbaric hydrogen storage vessels of type IV are encountering success for portable applications of fuel cell. During their use, these cylindric containers undergo repeated fill in/fill out cycles of H2-gaz. Under specific fillout conditions, an emerging detachment between the sealing inner layer (liner) and the composite wall, can be observed. This layer debonding also called collapse may limit the pressure release rate of H2-vessels or increase the residual gas pressure prescribed to avoid collapse.Experimental studies have been conducted by Air Liquide at vessel scale to identify some parameters responsible for the collapse onset. But the high cost of these studies and the complexity of the operating conditions makes the use of numerical tools necessary. That led to a numerical modeling approach. The main goal in the numerical approach is to model the cyclic mechanical response of a collapsed liner under fatigue – creep loadings.In this thesis, the purpose was to develop a mechanical constitutive law able to predict the cyclic deformation of a collapsed liner subjected to hydrogen pressure cycles.The liner was subjected to several environment variations due to: (i) the presence of residual water into the liner after initial hydraulic vessel tests, (ii) the temperature changes caused by the hydrogen compression/expansion, and (iii) the hydrogen diffusion/saturation. So, a preliminary work consisted in investigating the influence of each environmental factor on the polyamide 6 mechanical response. This first step allowed to outline a loading frame at laboratory scale that preserved main characteristics of the collapse phenomenon. Characterization tests on tensile specimens revealed that the liner could be modelled by a non linear viscoelastic law written within the thermodynamic framework of the irreversible processes in small deformations, and coupled with the temperature. Minor changes were introduced to extend the model capacity to capture liner behavior effects during fatigue – creep. These changes had negative impact on the manual method of model calibration, and consequently required to develop a specific identification strategy. The identification performance was assessed in different isothermal frames through stress rate, stress level and temperature effects. Then, the calibrated model was validated by taking temperature gradients into account, firstly on a tensile specimen, secondly within a H2-vessel
Parrens, Coralie. "Cyclage thermomécanique d'un acier inoxydable austénitique à haute température : influence sur le vieillissement et le comportement mécanique. Caractérisations expérimentales et modélisations". Thesis, Toulouse, INPT, 2017. http://www.theses.fr/2017INPT0015/document.
Texto completo da fonteAustenitic stainless steels are widely used in industrial applications. 310S stainless steel has high chromium and nickel contents, providing a competitive mechanical behavior for high temperature utilizations. Nevertheless, lifetime prediction is difficult to assess under coupled mechanical and thermal solicitations. Many data are available on aging and isothermal creep of austenitic stainless steels, but few consider the coupled effect of multiple solicitations. These data are insufficient to explain industrial macroscopic observations. The aim of this study was thus to explore the involved mechanisms in such a case. 310S stainless steel aging was investigated under various thermal cycling solicitations at 870°C. The obtained microstructures were characterized by numerous experimental means. The effect of thermal cycling on nucleation and growth of sigma phase precipitates was quantified. The results of the present work revealed enhanced sigma phase nucleation in these non-isothermal conditions. In addition, mechanical tests were carried out at 20, 650, 780 and 870°C under a large range of stresses. The results highlight a noticeable influence of microstructural evolution on elastic and creep properties of this alloy. Simultaneous increases of Young modulus, rupture stress and creep rates were evidenced. It was thus evidenced that lifetime prediction of components under thermomechanical cycling must take into account the microstructure change during lifetime. Finally, two models were proposed in order to assess microstructural changes and creep behavior that apply to isothermal and thermomechanical cycling conditions mimicking in service conditions of industrial components
Damerval, Claire. "Contributions à l'étude du comportement mécanique des composites cotac γ /γ'-NbC à moyenne et haute température". Paris 11, 1986. http://www.theses.fr/1986PA112034.
Texto completo da fonteGuigon, Camille. "Vieillissement par cyclage thermique de composites interlocks 3D à matrice polymère". Thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2015. http://www.theses.fr/2015ESMA0004.
Texto completo da fonteThe introduction of composite materials in critical structural parts for aircrafts represents a real technological breakthrough and requires specific studies to understand their behavior and durability. This work aims to characterize and understand the ageing mechanisms incarbon/epoxy 3D interlock composites when they are submitted to thermal cycling.For this purpose, a thermal cycle test (-55°C/120°C), whose heat and gaseous environment istotally mastered, was set up for the ageing of composite samples of elemental interlock pattern dimensions. Analysis of induced degradation mechanisms was achieved by i/ the development ofa 3D quantitative characterization method of the evolution of microcracks during cycling, basedon observations by microtomography RX and the development of a specific image processing procedure, ii/ the development of an in situ thermal cycle test under synchrotron light, coupled to a digital volume correlation technique, and iii/finite elements simulations taking into account the actual mesoscopic architecture of the samples and the thermo-viscoelastic behavior of thematrix.The results reveal complex thermo-chemo-mechanical couplings that are linked to four important parameters: time (and the number of cycles), the interlock architecture, the matrix toughness andits sensitivity to thermo-oxidation
Kudawoo, Ayaovi Dzifa. "Problèmes industriels de grande dimension en mécanique numérique du contact : performance, fiabilité et robustesse". Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM4771/document.
Texto completo da fonteThis work deals with computational contact mechanics between deformable solids. The aim of this work is to improve the performance, the reliability and the robustness of the algorithms and numerical models set in Code_Aster which is finite element code developped by Électricité De France (EDF) for its engineering needs. The proposed algorithms are used to solve high dimensional industrial problems in order to optimize the computational running times. Several solutions techniques are available in the field of computational contact mechanics but they must take into account the difficulties coming from non-smooth aspects due to Signorini-Coulomb laws coupled to large deformations of bodies and material non linearities. Firstly the augmented Lagrangian formulation so-called « stabilized Lagrangian » is introduced. Successively, the mathematical properties of the discrete operators are highlighted and furthermore a novel energetic function is presented. Secondly the kinematical condition with regard to the normal unknowns are reinforced through unconstrained optimization techniques which result to a novel formulation which is so-called « non standard augmented Lagrangian formulation ». Three types of strategies are implemented in the code. The generalized Newton method is developped : it is a method in which all the non linearities are solved in one loop of iterations. The partial Newton method is an hybrid technique between the generalized Newton one and a fixed point method
Widyanto, Bambang. "Oxydation à haute température de quelques alliages ferritiques : étude cinétique et morphologique". Compiègne, 1990. http://www.theses.fr/1990COMPD315.
Texto completo da fonteKudawoo, Ayaovi Dzifa. "Problèmes industriels de grande dimension en mécanique numérique du contact : performance, fiabilité et robustesse". Phd thesis, Université de Provence - Aix-Marseille I, 2012. http://tel.archives-ouvertes.fr/tel-00773642.
Texto completo da fonteRivière, Philippe. "Performances saisonnières des groupes de production d'eau glaçée". Phd thesis, École Nationale Supérieure des Mines de Paris, 2004. http://pastel.archives-ouvertes.fr/pastel-00001483.
Texto completo da fonteRoumy, Laurane. "Study of the Electro-Thermo-Mechanical Behaviour of a 4D Printed Actuator". Electronic Thesis or Diss., Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2024. http://www.theses.fr/2024ESMA0016.
Texto completo da fonteThe aim of this thesis was to develop an electro sensitive 4D printed hinge. 4D printing consists in using an additive manufacturing method coupled with an intelligent material that is sensitive to an external stimulus in order to create movement, the fourth dimension being time. For this study, the external stimulus is temperature, and heating is achieved by the Joule effect. Fused Filament Fabrication (FFF), which creates a three-dimensional structure by depositing melted polymer filaments, was chosen for its low cost, ease of use and low waste production. Polylactic acid (PLA) was used because it has excellent shape memory properties, is biosourced, is produced in Europe and is often used in FFF. To use the Joule effect, PLA reinforced with carbon black particles (CB/PLA) was considered. The result is a heat-sensitive material that can be heated remotely via an electrical circuit. An analysis of the electro-thermal and electro-mechanical couplings in this material was therefore carried out. The first step was to establish the link between the properties of the printed sample and the printing parameters. Rectangular specimens were then heated using the Joule effect and observed with a thermal camera in order to study the behaviour of the material when subjected to three different voltages. A model based on the heat equation was used to predict the temperatures reached within the material. Under electrical cycling, a change in the CB/PLA microstructure was observed, resulting in a change in electrical resistance. A study of the electro-mechanical coupling was then carried out using monotonic and cyclic tensile tests to analyse changes in electrical resistance under mechanical stress and in the context of repeated use. The advantages of a structure with a longitudinal printing angle, along the loading direction, were demonstrated by superior electrical and mechanical properties and improved durability. Other printing angles were also tested and the classical laminate theory was applied to the 3D printed specimens. Damage in the tensile specimens was monitored using acoustic emission, scanning electron microscopy and micro computed tomography. The development of crazes perpendicular to the loading direction was demonstrated. Finally, a hinge was designed and tested for a bending angle of 90°. The printing parameters were optimised to reduce the influence of residual stresses due to the manufacturing process during the programming step of the hinge. The results showed that the temperature of the plate and the printing speed had a noticeable influence. The reproducible deployment of a hinge with approximately 80% of recovery was obtained, and the force deployed and the deployment speed were measured. The repeated use of such a hinge and its durability were investigated by carrying out ten successive deployment cycles. The influence of programming and triggering temperatures was also studied. Finally, a first approach of reversible hinge was proposed. It was thus demonstrated that it is possible to create an optimised prototype of a 4D printed hinge that can be remotely triggered by Joule effect
Dupont, Laurent. "Contribution à l'étude de la durée de vie des assemblages de puissance dans des environnements haute température et avec des cycles thermiques de grande amplitude". Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2006. http://tel.archives-ouvertes.fr/tel-00091782.
Texto completo da fonteLa première partie de cette étude présente les caractérisations électriques de composants à semi-conducteur, afin de justifier le choix des diodes Schottky SiC et de transistor CoolMOS Si pour une utilisation à haute température. Ces composants sont alors intégrés dans un véhicule de test (module de puissance) adaptée à une localisation sur le réacteur. L'objectif est d'évaluer les performances électriques des éléments actifs à haute température, et la technologie d'assemblage par brasure des substrats céramiques sur une semelle AlSiC. En complément d'une campagne expérimentale, s'appuyant sur un cyclage thermique de grande amplitude, une évaluation numérique des sollicitations dans l'assemblage permettra de mieux comprendre les mécanismes de défaillances et les moyens permettant d'augmenter la durée de vie des modules de puissance dans ces conditions d'utilisation.
Afin de trouver des solutions d'intégration et de chercher à améliorer la durée de vie des assemblages, la dernière partie de cette étude présente les résultats expérimentaux, dans des conditions tout aussi sévères, pour de nouveaux véhicules de test, sans élément actif, composés de substrats céramiques de technologie différente. Les produits testés comportent des céramique AlN et Al2O3 dont les métallisations, avec ou sans dimples, présentent des géométries différentes. Nous évaluerons également, des substrats de technologie AMB avec des solutions DAB et Si3N4. Finalement, une nouvelle étude numérique est réalisée sous ANSYS dans le but d'estimer l'influence ce des substrats céramiques sur la durée de vie de l'assemblage. Finalement, nous tenterons de proposer des règles de conception permettant d'augmenter la durée de vie des assemblages de puissance.
Terzolo, Laurent. "Vers une prédiction de la durée de vie des outils de forge à chaud par la détermination numérique du régime thermique et de l'usure abrasive". Phd thesis, Paris, ENMP, 2004. http://www.theses.fr/2004ENMP1236.
Texto completo da fonteIn forging industry, we want to decrease production costs, in order to obtain the cheapest rate : tool cost / workpiece. Numerical simulation permit to study feasability using low cost developpements. Nowadays, we can use numerical simulation to optimize tool shape. To increase, tool life, we must take into account two main factors : wear and thermal-mechanical loads undergone by tools. In this document, we use a thermal-mechanical and a numerical formulation for a thermal-mechanical coupled problem for a complete system : tool/workpiece. The solution of this problem, permit us to simulate tool behaviour during hot forging process. CPU time increase because of this formulation, so we investigate several strategies to decrease this CPU time. We can use those strategies and after comparing them, we can notice their own advantages. For each method, user must choose between time and reliabilty. This document, can help user to choose the best method to solve his problem. Thanks to thermal and mechanical results obtained on the tools, we can simulate tool wear. Then finally, we implemented four different methods to simulate thermal and mechanical cycling, in order to simulate forging passes
Lorca, Thierry. "Mécanisme de sortie de la phase M du cycle cellulaire : inactivation de la kinase cdc2". Montpellier 1, 1993. http://www.theses.fr/1993MON1T004.
Texto completo da fonteBen, Kaabar Aymen. "Durabilité des assemblages céramique-métal employés en électronique de puissance". Thesis, Lyon, INSA, 2015. http://www.theses.fr/2015ISAL0064/document.
Texto completo da fonteThe power electronics components (and still will have!) have a great influence on the energy and transport sectors. These parts are made of ceramic-copper assemblies for which the mechanical strength must be controlled to ensure durability about 30 years under the thermal cycles increasingly larger. A failure mechanisms analysis in DBC (Direct Copper Bonding) assemblies used in power electronics is studied (the delamination along the interface copper - ceramic and/or the brittle ceramic fracture). To identify the elastoplastic behavior of copper, we showed that it’s necessary to use a copper plate having undergone the heat hole treatments related to the assembly process. The ceramic gragile elastic behavior is descrobed within the Weibull statictics framework. Consequently, a copper-ceramic delamination characterization under four points bending made it possible to identify a cohesive model for the interface. The cohesive calibration parameters is carried out by using the data in two scales: i) strentgh-displacement macroscopic ii) local cracking optical follow-up with imposed displacement. The mechanical integrity of DBC assemblies of different thickness of copper and ceramic has been studied. We showed that the configurations with a ratio close to the unit are most dangerous by generating a delamination, which continues under thermal cycling. This risk of delamination can be notably reduced by structuring the copper circumference surface with cylindrical holes distributed periodically. Thus, a finite elements model allowing us to evaluate the most promising assemblies in term of durability, was estabilshed. In the absence of geometrical defects, the copper layer must remains, even in the delamination case whose face induces a concentration stress
Takla, Mohamad. "Contribution à l'étude du comportement des argiles saturées et non saturées : analogie avec les matériaux carbones". Châtenay-Malabry, Ecole centrale de Paris, 1989. http://www.theses.fr/1989ECAP0087.
Texto completo da fonteBeck, Kévin. "Étude des propriétés hydriques et des mécanismesd'altération de pierres calcaires à forte porosité". Phd thesis, Université d'Orléans, 2006. http://tel.archives-ouvertes.fr/tel-00125704.
Texto completo da fontepierres de monuments vis-à-vis de l'altération. A cet effet, deux pierres de construction, dont certaines
caractéristiques principales sont assez semblables (porosité totale, résistance mécanique), sont étudiées : le
tuffeau blanc, qui est largement employé dans les constructions des châteaux du Val de Loire, et la pierre de
Sébastopol, utilisée en région parisienne.
Tout d'abord, une observation des différents types de dégradations rencontrées in-situ ainsi qu'une étude de
cas sur une pierre altérée naturellement ont été réalisées afin de constater les différentes morphologies
d'altération et d'identifier l'eau comme l'agent vecteur des phénomènes d'altération.
Dans un second temps, une caractérisation multi-échelles a été effectuée afin de bien connaître les pierres
non-altérées du point de vue de leur constitution minéralogique, de la morphologie de leur milieu poreux et
surtout de leurs propriétés hydriques (capacité de rétention d'eau, propriétés de transfert de l'eau sous forme
liquide et sous forme vapeur) mais aussi de leur comportement hydro-mécanique.
La dernière partie est consacrée à la durabilité des pierres mises en oeuvre avec l'étude de la compatibilité
entre les matériaux utilisées en restauration. En effet, le comportement des pierres durant un essai de
vieillissement artificiel est comparé. La réaction différente des deux pierres face à ce même processus
d'altération est à relier directement à leurs propriétés hydriques très dissemblables. En dernier lieu, une
formulation et une caractérisation hydro-mécanique de joints de mortier est proposée afin de déterminer les
critères de compatibilité entre le mortier et les pierres en oeuvre.
Fesquet, Didier. "Mécanisme d'activation de la kinase cdc2 : purification de la thréonine 161 kinase activatrice des complexes CDK-cyclines". Montpellier 1, 1993. http://www.theses.fr/1993MON1T026.
Texto completo da fonteRahma, Afif. "Modélisation probabiliste des paramètres de lois élastoplastiques : modèle cyclade". Châtenay-Malabry, Ecole centrale de Paris, 1991. http://www.theses.fr/1991ECAP0172.
Texto completo da fonteOrenes, Balaciart Salvador. "In Situ Characterization by Acoustic Emission and X-Ray μ-Computed-Tomography of the Effects of Temperature, Aging, and Multi-Axial Loads on Damage Onset in 3D Woven Organic Matrix Composites for Aeronautical Applications". Electronic Thesis or Diss., Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2024. http://www.theses.fr/2024ESMA0010.
Texto completo da fonteThe field of aeronautical engineering has seen considerable advancements over the past decades in materials science. Carbon fibre Three-Dimensional Woven Organic Matrix composites (3DOMC) are increasingly used as elements of structural parts close to aircraft engines and in aero-engine fan blades. These materials are therefore requested to operate in high-performance ranges subjected to multi-axial mechanical solicitations at different temperatures and exposed to cold/hot thermal cycling. Although there is substantial literature on the effects of such solicitations on the fracture behavior and ultimate damage mechanisms of 3DOMC, there is a limited study on the initial damage mechanisms. This gap is particularly critical since the onset of damage dictates the usability of such components; from operational standpoint, no damage is permissible in service in these parts. This work aims to develop a novel experimental methodology to characterize the onset of damage in 3DOMC for different multi-axial solicitations encountered in-service.To achieve this, an in situ test has been designed coupling μ-Computed Tomography (μ-CT) and Acoustic Emission (AE), successfully identifying multi-axial damage initiation during tensile test and Eccentric Compression Bending (ECB) in in-axis and off-axis specimens. The effect of temperature has been addressed via in situ test implementing the new developed methodology test at high (120ºC) and low (-30ºC) temperature; it has been found damage initiation mechanisms are strongly dependent on temperature.The effect of thermal cycling between 120ºC and -55ºC on damage onset has been characterized by AE and ex situ (μ-CT). Further, damage propagation up to 1000 cycles has been characterized in detail in the 3D woven meso-structure. Finally, thermal cycling degradation and ageing on damage onset is investigated in static in situ tensile test
Angely, Christelle. "Propriétés mécaniques et fonctionnelles des cellules épithéliales respiratoires exposées à une toxine bactérienne : l’adénylate cyclase". Thesis, Paris Est, 2018. http://www.theses.fr/2018PESC0058/document.
Texto completo da fonteThe increase in respiratory infections involving virulent factors of bacterial origin has become a major public health issue. A better knowledge of the cell respiratory response in the course of the initial cell invasion by bacterial toxins is important from the pathophysiological and therapeutical point of views.The purpose of this work is to decipher the cellular and molecular mechanisms involved in the exposition of respiratory epithelial cells to the adenylate cyclase toxin (CyaA) produced by Bordetella pertussis which is the whooping cough agent. We have chosen this toxin for its multiple capacities of penetrating a wide range of eukaryotic cells. Indeed, this toxin enables direct translocation of its catalytic domain across the plasma membrane of target cells using the endogen calmoduline to increase the cAMP rate at supraphysiological levels. However, the effects of these changes on mechano-chemical signaling (mechanotransduction) pathways remain largely unknown while it affects cellular functions and cell integrity. So, we perform an evaluation of cellular functions as well as mechanical and adhesion properties of respiratory epithelial cells exposed to CyaA toxin in order to detect some critical modifications in the mechanotransduction processes.In a preliminary study aiming at defining physiopathological concentrations of CyaA toxin used in our experiments, we determined the cell viability degree for 3 concentrations of CyaA toxin (0.5; 5 and 10 nM). We found that the smallest concentration (0.5 nM) did not affect cell viability whereas inducing supraphysiological cAMP levels in less than one hour.Then, we assessed the effects of CyaA toxin on cell migration and repair phenomenon, on ciliary beating and on cell permeability of epithelial cells representative of the different levels of the respiratory tract. The toxin induces a decrease in cell migration and repair, an increase in cell permeability suggesting a weakening of lateral cell-cell junctions.Immunostaining was performed on intracellular and interfacial structures of alveolar epithelial cells exposed to the 3 concentrations of CyaA toxin. Results show that CyaA toxin is able to induce cytoskeleton remodeling and a decrease in the number of focal adhesions. Finally, a refined analysis of mechanical properties and adhesion parameters was performed on the same cells by 2 techniques of micro/nanomanipulation modified to permit at the same time, an evaluation of cell adhesion and cell rigidity (Atomic Force Microscopy with indentation and force spectroscopy to characterize the number of bond during adhesion reinforcement and multiscale Magnetic Twisting Cytometry). To evaluate the role of cAMP on cellular and molecular changes, we tested the enzymatically inactive form of CyaA toxin called CyaAE5 which could not permit to increase the intracellular cAMP rate.The AFM experiments have revealed that the main effect of CyaA toxin is to decrease the number of associated integrin-ligand bounds (meaning an alteration of clustering) while, at the smallest concentration of CyaA toxin, we observe an increase in cell rigidity with an individual bound reinforcement, a result consistent with MTC results. Nevertheless, CyaE5 does not exhibit such cellular effects. On the whole, these results suggest that CyaA toxin affects the mechanotransduction pathways of cells exposed to the toxin, a result which is in agreement with the expected effects of cAMP increase (notably cytoskeleton remodeling, lateral junction alteration and inhibition of Rac1 expression) what brings a new vision of the cytotoxicity induced by the adenylate cyclase toxin
Fitouhi, Mohamed Chahir. "Cycle Time in the Lumber Industry Supply Chain. Diagnostics and Analysis". Thesis, Université Laval, 2006. http://www.theses.ulaval.ca/2006/24135/24135.pdf.
Texto completo da fonteBouden-Jedidi, Jihed. "Contribution à la caractérisation en cyclage hygrothermique d'un matériau composite : application à l'avion supersonique". Saint-Etienne, EMSE, 2005. http://www.theses.fr/2005EMSE0016.
Texto completo da fonteEnvironmental conditions are known to cause degradation of fibre-reinforced polymer matrix composites. Thus they may have some critical effects on the in-service structural durability. When exposed to temperature and humid environment, polymer matrix composites undergo dimensional and stress state changes due to moisture induced swelling and thermal expansion. The coupling between moisture and temperature and the evolution with time are essential, in particular in the case of cyclic conditions. The study is related to a supersonic transportation application where polymer matrix composites utilized in primary structures are subjected to particular hygrothermal flight-cycles. In fact, the particular point in this study is the drying effect of supersonic flight at high temperature, around 130°C, on the durability of the material. This phenomenon constitutes an entirely new situation for these materials in contrast with a classical subsonic flight at low temperature –50°C. The objective of the study is to characterize the in-service material state. First, an exhaustive bibliographical summary of the influence of moisture on polymer matrix composites durability is presented. Then, an identification method based on Fick's model is proposed to extract the diffusion properties from the gravimetric curves of IM7/977-2 carbon/epoxy composite material. Thanks to this identification method, diffusion parameters can be determined without necessary reach saturation. The effect of laminate's internal mechanical state (stacking sequence) on diffusion parameters values is underlined. Two different experimental methods are used to identify the coefficients of thermal and moisture expansions (CTE and CME), indicators of the structure dimensional stability under in-service conditions. Then, moisture concentration profiles induced by hygrothermal cycles are simulated using a Fickian diffusion model and resulting internal stresses estimated within the framework of hygro-thermo-elasticity. Numerical simulations show that the supersonic flight-cycles induce a material drying on the long-term. Finally, the challenge is to design accelerated cycles in a more rational way based on the knowledge of the internal mechanical state of specimens. Thanks to numerical simulations, two different approaches are used to define accelerated experimental conditions such as the hygroscopic state of the laboratory specimens is close to the in-service hygroscopic state. The first designed accelerated cycle is 60 times faster than the in-service one. The second accelerated cycles, including negative temperatures for a better representation of the transient stress during the subsonic part of flight-cycles, is 25 times faster than the in-service one. Then, these accelerated cycles are tested in laboratory. Experiments showed that the long-term hygrothermal fatigue induce significant changes in the material properties a drop of the glass transition temperature of about 20°C and micro-cracks, specific effect of accelerated cycles including low temperatures
Baazaoui, Ahlem. "Optimisation thermomécanique du packaging haute température d’un composant diamant pour l’électronique de puissance". Phd thesis, Toulouse, INPT, 2015. http://oatao.univ-toulouse.fr/14490/1/baazaoui.pdf.
Texto completo da fonteSheshka, Raman. "Le rôle mécanique de " power stroke " dans la contraction musculaire". Phd thesis, Palaiseau, Ecole polytechnique, 2012. http://www.theses.fr/2012EPXX0070.
Texto completo da fonteThis thesis is devoted to the modeling of mechanical functioning of myosin II/actin in- teraction, responsible for active force generation in skeletal muscles at nanometer scale. The muscle contractile units contain actin filament and myosin II filaments formed by an assembly of myosins II. The myosin II is molecular motor that periodically attaches and detaches to the actin filament in presence of ATP. In order to understand the phenomenon of muscle contraction from mechanical point of view, we follow the approach developed by the Brownian ratchets community, which replaced the conventional chemistry-based interpretation of active force generation by a study of Langevin dynamics of mechanical systems with well defined energy landscapes. We focus on the role of the conformational change known as power stroke in the functioning of myosin II. We identify the power stroke as the main driver of contractility. The attribution of active role to power stroke reflects the biological reality imprinted in the molecular motor functional cycle. We propose an innovative mechanical model and by emphasizing the active role of the power stroke we are therefore building a bridge between processive and nonprocessive motors. In this Thesis we present the first examples of models of nonprocessive motors driven exclusively by the power stroke and exploiting the well known phenomenon of stochastic resonance
Cot, Emilie. "Inhibition chimique des Cdk : mécanisme biochimiques et conséquences cellulaires". Thesis, Montpellier 2, 2010. http://www.theses.fr/2010MON20054.
Texto completo da fonteCycline Dependant Kinases (Cdk) control cell cycle progression. The study of their roles is often difficult because of functional redundancy; when a given Cdk is absent, others may compensate. The main role of Cdk2 in the cell cycle is in the initiation of DNA replication, but absence of Cdk2 is compensated for by Cdk1. For example, mice with a genetic knockout of Cdk2 are viable. The chemical inhibition of Cdks may limit compensation by other Cdks. Therefore, to study Cdk2 roles, we have studied chemical inhibition by NU6102, which seems to be selective for Cdk2 in the Xenopus model. To verify the selectivity and study parameters that determine selectivity, we have designed and produced mutants of Cdk2 which are resistant to NU6102, allowing restoration of function in the presence of inhibitor. Moreover, we demonstrate in vitro that NU6102 is selective for Cdk2 compared to other human Cdks, and we describe phenotypes induced by NU6102 in cultured cells, which are interesting in the light of potential applications of NU6102 in cancer chemotherapy. Cdk activity is essential for initiation of DNA replication, but in metazoans no essential substrates are known. To identify potential Cdk substrates during DNA replication, we have performed a proteomics screen of the proteins loaded onto chromatin in the presence or absence of Cdk activity, in the Xenopus model. The results suggest that Cdk activity is not only required for assembling DNA replication complexes onto origins of replication, but may also be implicated in other cellular functions
Sheshka, Raman. "Le rôle mécanique de " power stroke " dans la contraction musculaire". Phd thesis, Ecole Polytechnique X, 2012. http://pastel.archives-ouvertes.fr/pastel-00784006.
Texto completo da fonteRegorda, Alessandro. "Évolution thermo-mécanique des systèmes de subduction-collision". Thesis, Université Côte d'Azur (ComUE), 2017. http://www.theses.fr/2017AZUR4013/document.
Texto completo da fonteThe aim of this work was to develop a 2D thermo-mechanical model to analyse in detail the effects of the shear heating and mantle wedge hydration on the thermal state and dynamics of an ocean/continent subduction system. The thermal setting and dynamics that result from models with shear heating and/or mantle hydration are directly compared to a model that does not account for either (Marotta and Spalla, 2007) to analyse their effects on both the strain rate and the viscosity. The new model show the activation of short-wavelength mantle convection related to the hydration and the serpentinisation of the mantle wedge, with the consequent recycling of oceanic and continental subducted material. The effects of the subduction velocities on the size of the hydrated area are also analysed, andpredictions of the pressure-temperature evolutions of crustal markers and the thermal field, which affect different portions of subduction systems, are used to infer the thermal regimes that affect the models. Similarly, the model can help to understand extensively both the distribution and the evolution, in time and space, of metamorphic conditions characterised by contrasting P/T ratios in subduction systems. In a second phase, P-T predicted by the model has been compared with natural P max -T estimates related to the Variscan metamorphism, from both the present domains of the Alps and from the French Central Massif. However, the model did not allow to compare simulated P-T paths with successive metamorphic stages recorded and preserved by the rocks during their metamorphic evolution, because of the lack of exhumation of subducted material up to the shallowest portion of the crust
Caniven, Yannick. "Cinématique et mécanique des failles décrochantes à l'échelle de temps du cycle sismique : apports d'un modèle expérimental". Thesis, Montpellier 2, 2014. http://www.theses.fr/2014MON20057.
Texto completo da fonteAverage seismic cycle duration extends from hundred to a few thousands years but available geodetic measurements, including trilateration, GPS, Insar and seismological data extend over less than one century. This short time observation scale renders difficult, then, to constrain the role of key parameters such as fault friction and geometry, crust rheology, stress and strain rate that control the kinematics and mechanics of active faults.To solve this time scale issue, I have developed a new experimental set-up that reproduces scaled micro-earthquakes along a strike-slip fault during several hundreds of seismic cycles. The model is constituted by two polyurethane foam plates laterally in contact, lying on a basal silicone layer, which simulate the mechanical behaviour of an elastoplastic upper crust coupled with a ductile lower crust, respectively. For each experience about 4000 horizontal-velocity field measurements are recorded. The analysis of model-interseismic, coseismic and postseismic surface displacements and their comparison to seismogenic natural faults demonstrate that our analog model reproduces correctly both near and far-field surface strains. I also performed surface-velocity field inversions to assess the spatial distribution of slip and stress at depth along the fault plane. To compare the experiences, we have developed several algorithms that allow studying the spatial and temporal evolution of the main physical parameters and surface deformation processes that characterise the seismic cycle (magnitudes, stress, strain, friction coefficients, interseismic locking depth, recurrence time, ...). My first results suggest that far-field boundary-velocity conditions play a key role on the seismic cycle by influencing earthquake magnitudes and recurrence time, as well as the capability of the fault to generate characteristic earthquakes. We observed that low loading rate favors rare but large strong characteristic events and high loading rate numerous low to moderate magnitude more distributed microquakes. My first hypothesis is that this behaviour may be controlled by the brittle/ductile coupling at the base of foam plates. For a high loading rate, viscous forces in the silicone layer increase as well as coupling at the base of the foam plates. These features force the base of the fault to slip at a velocity close to the far field velocity and induce a more heterogeneous stress field along the fault favoring low to moderate microquakes. For a low loading rate, silicone almost behaves as a newtonian fluid and viscous forces strongly decrease, allowing the fault to remain locked for a longer period and to accumulate more elastic strain. Stresses are then relaxed by larger seismic events.Finally, I investigate experimentally the role played by along fault initial normal stress variations on coseismic slip and long term fault behavior. Results show that coseismic slip patterns are strongly controlled by variations in fault strength and subsequent accumulated shear stress along fault strike. Major microquake events occur preferentially into zone of major shear stress asperities and coseismic slip distributions follow similar trends than initial normal stress variations along the fault. Moreover, our experiment suggest that the heterogeneity of initial stress state along the fault influence the regularity of the seismic cycle and, consequently, long term fault slip behavior. Results of this parametric study comfort, then, the hypothesis that coseismic slip distribution along earthquake ruptures may provide relevant informations on unknown initial stress state and could thus improve our understanding of seismic hazard.Our experimental approach appears then, as an efficient complementary method to investigate earthquake dynamics
Cailleau, Pascal. "Effets thermiques et dommage mécanique au cours de la fatigue du polypropylène". Poitiers, 1996. http://www.theses.fr/1996POIT2275.
Texto completo da fonteMosca, Matthieu. "Etude du mécanisme d'action de l'interféron alpha dans les néoplasmes myéloprolifératifs classiques". Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS516/document.
Texto completo da fonteClassical BCR-ABL-negative myeloproliferative neoplasms (MPN) include Polycythemia Vera (PV), Essential Thrombocytemia (ET) and Primary Myelofibrosis (PMF). They are acquired clonal disorders of hematopoietic stem cells (HSC) leading to the hyperplasia of one or several myeloid lineages. They are due to three main recurrent mutations affecting the JAK/STAT signaling pathway: JAK2V617F and mutations in calreticulin (CALR) and thrombopoietin receptor (MPL). Interferon alpha (IFNα) is the only curative treatment that induces not only a hematological response of ET, PV and early MF but also a molecular response both on JAK2V617F or CALR mutated cells. In this study, we wanted to know how and with what kinetics IFN impacts the different mutated hematopoietic compartments. Thus, we have performed a prospective study with a cohort of 50 patients treated by IFNα for 3-5 years. The MPN diseases distribution was 44% ET, 45% PV and 11% MF. This cohort included 33 JAK2V617F-mutated patients, 11 CALR-mutated patients (7 type 1/type 1-like and 4 type 2/type 2-like), 2 both JAK2V617F- and CALR-mutated patients and 1 MPLW515K-mutated patient. At 4-month intervals, the JAK2V617F or/and CALR mutation variant allele frequency was measured in mature cells (granulocytes, platelets). Simultaneously, we have also determined the clonal architecture by studying the presence of the JAK2V617F or CALR mutations in colonies derived from the different hematopoietic stem and progenitor cell (HSPC) populations (CD90+CD34+CD38- HSC-enriched progenitors, CD90-CD34+CD38- immature progenitors and CD90- CD34+CD38+ committed progenitors). After a median follow-up of 30 months, we observed that IFNα targets more efficiently and rapidly the HSPC particularly in HSC-enriched progenitors, than the mature blood cells in JAK2V617F patients (p<.05). Moreover, homozygous JAK2V617F clones responded more rapidly than heterozygous clones in all hematopoietic cell compartments showing that the intensity of JAK2V617F signaling is correlated with the efficacy of IFNα. These observations were slightly increased after a median follow-up of 51 months. In contrast, with a median follow-up of 30 months for CALR mutated patients, IFNα targeted similarly the HSPC and the mature cells. Moreover, IFNα induced a less rapid response to target CALR-mutated HSPC than the JAK2V617F HSPC (p<.05). The role of associated mutations at diagnosis was also investigated in the IFNα-mediated HSPC molecular responses using a NGS targeted myeloid panel. While in JAK2V617F-mutated patients, we found that the number of associated mutations did not impact the HSPC molecular response of the JAK2V617F clone, in CALR-mutated patients, even if the number of cases was low, the only molecular responders were those not associated with other mutations. Using Ba/F3-MPL cellular models and primary cells, we observed that JAK2V617F was more prone to sensitize to IFNα signaling (increased Phospho-STAT1 and IFN-stimulating genes (ISGs)) compared to controls or CALRdel52 mutated cells.Altogether, our results show that IFNα differentially targets the human JAK2V617F- and CALR-mutated HSPC and mature cells. Moreover, the molecular response was dependent not only on the JAK2V617F or CALR mutated status but also on the presence of other associated mutations
El, Aour Filho Rachid Aref. "Mécanisme de la dérégulation du cycle cellulaire de l'hôte par Staphylococcus aureus". Thesis, Rennes, Agrocampus Ouest, 2016. http://www.theses.fr/2016NSARB283/document.
Texto completo da fonteStaphylococcus aureus is a Gram-positive bacterium that colonizes the skin of healthy animals and humans. In certain conditions, including the disruption of the commensal microbiota, S aureus can cause different diseases by deviating the host defense functions. Recently, our group has shown that the methicillin-resistant S. aureus (MRSA) MW2 (USA400) strain causes delay in the transition of the G2/M phase of HeLa cells. In the present work, we demonstrated that this action is initiated by components of the supernatant of the S. aureus culture. Different supernatant fractions were obtained by size exclusion chromatography and were analyzed by mass spectrometry, which allowed to identify phenol-soluble modulins alpha (PSMa) as responsible for the host cell cycle delay.Confirming the involvement of these modulins in the delay, the MRSA LAC¿psma strain, which is deficient in PSMa1–4, did not affect the normal progression of the cycle in HeLa cells. In addition, the treatment of these cells with synthetic PSMa1 and PSMa3 caused delay in the transition of the G2/M phase associated with the decreased production of host ß-defensins. Lastly, we demonstrated that the MW2 strain, which produce PSMa, decreases the level of optineurin and optineurin phosphorylated at serine 177, a host protein that is involved in the G2/M phase transition. The work conducted in this thesis represents an important achievement in the understanding of how S. aureus interferes with the host cell cycle, revealing a new role for PSMa produced by this bacterium
Kacem, Hassine. "Influence des chargements cycliques sur les propriétés mécaniques des aciers à 9% de nickel et 316L dans des conditions cryogéniques". Thesis, Lille 1, 2016. http://www.theses.fr/2016LIL10056.
Texto completo da fonteIn last few decades, there has been increasing interest in the exploitation of the Liquefied Natural Gas (LNG). It is a fast growing market with many projects of storage terminal installation. Liquefied natural gas is transported and stored in reservoirs with increasingly important capacities at very low temperatures (~ -163°C). This requires the use of special materials with tailored properties at cryogenic temperatures. The storage terminals must operate safely during their life. This imperative security must be taken into account at the design stage and throughout the operating period. This study provides a significant contribution to the verification and understanding of the behavior of 9% Nickel steel and 316L austenitic steel used for the construction of large reservoirs and loading-unloading arms respectively. Mechanical behavior of these materials is studied at room temperature and -196°C using conventional mechanical tests and Small Punch Test. The cycling test matrix is proposed in order to assess effects on installations due to consecutive filling-emptying cycles. The mechanical characteristics of the materials and some of welds are carried out and compared before and after cycling
Lemesle, Charlotte. "Peintures auto-stratifiantes bio-sourcées : concept et mécanisme". Thesis, Lille 1, 2020. http://www.theses.fr/2020LIL1R012.
Texto completo da fonteThe goal of this PhD thesis is to design bio-based self-stratifying coatings for railway applications. This process provides a multifunctional coating in a single application step, offering an interesting alternative to conventional multi-layer coating process as it meets current environmental and industrial constraints, such as reduction of waste production, electricity consumption and cost. Over the last three years, self-stratifying coatings based on different bio-based epoxy and silicone resins were set up. As a first step, theoretical models were used to predict the layering of the different binary epoxy/silicon systems. However, the first experimental results obtained were not clearly correlated with the predicted ones in term of stratification level. Indeed, self-stratification phenomenon is influenced by many factors which are usually not taken into account in the theoretical models. The influence of these parameters on the stratification process was therefore investigated during this thesis. It led to the conclusion that the nature, the surface energy and the polarity of the resins, the solvent volatility, the curing temperature and the nature of the cross-linking agent have an impact on the degree of stratification. Thereafter, ageing tests were performed on the coatings showing two perfectly distinct stratified layers, to compare their resistance to humidity and UV radiation to those of conventional multi-layer coatings. Finally, a comparative Life Cycle Assessment was carried out to quantify the environmental impact of the self-stratifying process using bio-based resins compared to the multilayer process using oil-based resins
Simon, Guillaume. "Dynamique multi-échelles en fluide stratifié tournant, instabilité de cisaillement et cyclone intense". Ecully, Ecole centrale de Lyon, 2007. http://bibli.ec-lyon.fr/exl-doc/gsimon.pdf.
Texto completo da fonteThis study is about turbulent fluctuation in sheared, stratified and rotating base flows with respect to the admissibility condition on the mean flow. This admissibility condition is known as thermal wind relation for meteorologists and thermohaline circulation for oceanographers. In contrast to the previous study on baroclinic instability, mainly quasi-two-dimensional, the advance is that the flow is three-dimensional and the dynamics is given by the three-periodic Boussinesq equations. In such a flow, turbulence, waves and instability are interleaved. The linear problem will be tracked by Rapid Distortion Theory (RDT) and the non-linear aspect by pseudo-spectral Direct Numerical Simulation (DNS). Results coming from TDR and SND, due to their spatial homogeneity, are a knowledge database that can be directly used for sub-grid scale parameterisation. The vortex structures are investigated by the vertical vorticity skewness and with three-dimensional visualisations. In the simulated flow we find that cyclonic vorties are predominant over anticyclonic structure
Camps, Guillaume. "Etude des interactions chemo-mécaniques pour la simulation du cycle de vie d'un élément de stockage en béton". Toulouse 3, 2008. http://thesesups.ups-tlse.fr/324/.
Texto completo da fonteIn order to achieve acceptable safety condition during the concrete package handling and to ensure the nuclear waste confinement over several decades, Andra plans to develop fibre reinforced concrete package. The research program presented in this work aims to develop the chemo-mechanical constitutive model for the fibre reinforced concrete. The model considers both the early age behaviour of the concrete and the long term behaviour. The first part of this study consists in performing an experimental program to characterise the physical properties of concrete. The second part was devoted to the development of behaviour laws for plain and fibre-reinforced concrete in a finite element code. We are now able to predict the complete life cycle of nuclear waste packages
Solignat, Maxime. "Cycle de réplication du virus Chikungunya chez l'homme et l'Aedes : tropisme cellulaire et mécanisme d'entrée". Montpellier 1, 2009. http://www.theses.fr/2009MON1T007.
Texto completo da fonteChikungunya virus (CHIKV) is a mosquitoe transmitted Arbovirus and more particulary by the Aedes mosquitoe genus. This Alphavirus which belongs to the Semliki Forest group was identified like the responsible [i. E. Responsable] agent for the epidemic disease in 2005 and 2006 on the territory of La Reunion and in the Indian Ocean. Whereas this disease was generally regarded as nonfatal, 256 deaths were directly allotted to the virus at the time of the epidemic episode in La Reunion. Although it was isolated in 1952, the CHIKV remains poorly understood and the brutal modifications of the physiopathology of the infection by this virus in La Reunion are unexplained to date. No treatment is available at the present time. Among envelopped viruses, there are various entry pathways in the host cell which are as many targets to inhibit the replicative cycle of these viruses. The main aim of my thesis consisted in characterizing the entry mechanism of CHIKV in human cells and in mosquitoe cells of the Aedes family. Thus, we described for the first time the entry mechanism of CHIKV in these target [i. E. Targets] cells and this, for various viral isolates. More particularly, we highlighted the role of the clathrin mediated endocytic pathway and the endosomes vesicles in these mechanism [i. E. Mechanismes]. Finally, we studied the influence of cellular and molecular interactions between the CHIKV and the endosymbiotic bacteria Wolbachia on viral replication. This obligatory intracellular bacteria which is present in the natural populations of Aedes albopictus could be implied in the transmission cycle and the viral pathogenesis of the CHIKV as it is already shown for other virus-arthropods-Wolbachia systems
Dominice, Carole. "Etude du mécanisme d'action de composés antinéoplasiques d'origine marine, les didemnines". Montpellier 2, 1996. http://www.theses.fr/1996MON20031.
Texto completo da fonteSaint-Pierre, Nicolas. "Mise en œuvre de l'implant piézoélectrique : application au suivi du cycle de vie d'un matériau composite". Lyon, INSA, 1996. http://www.theses.fr/1996ISAL0077.
Texto completo da fonteThe ultrasonic technics have shown their utility for the mechanical characterisation of materials. Velocity and attenuation of ultrasonics depends on the microstructure and so, they are linked to the mechanical properties of the propagating medium. But for very attenuative materials, classical methods such as impulsive spectroscopy are not very efficient. So, we have developed an original method based on the measurement of the electric impedance of a piezoelectric element inserted in the material to be characterized. It is also possible, with this technic, to monitor the properties of a polymer material during its different physical states (liquid, glass or gel). We have developed and validated an analytical model and we show that the electrical impedance of the piezoelectric implant depends on the properties of the surrounding materials. Then, by using an identification algorithm, we can deduce the values of velocity and attenuation of the material by minimising the difference between experimental and simulated values. In this theoretical approach unidimensional model suppose that the piezoelectric element and the materials have parallel faces and that the different media are well coupled. In practical case, parallelism or bonding defects can appear. We take in account these defects in the numeric simulation and we validate these simulations by comparison of the simulated and measured spectra. Considering the Kramers Kronig relationships that link the acoustical parameters (velocity and attenuation) of the material, we determine for each defect, the tolerances that doesn't affect the result of the optimisation algorithm. The last part of this study concerns the monitoring of the properties of a composite during its polymerisation and to its hydrolytic degradation
Maalouf, Samer. "Étude et conception d'un système thermodynamique producteur du travail mécanique à partir d'une source chaude à 120°C". Thesis, Paris, ENMP, 2013. http://www.theses.fr/2013ENMP0074/document.
Texto completo da fonteLow-temperature waste-gas heat sources (< 120-150°C) exiting several industrial processes could be recovered for electricity production and constitute an effective mean to reduce primary energy consumption and carbon dioxide emissions. However, technical barriers such as low conversion efficiency, large needed heat transfer area, and the presence of chemically corrosive substances associated with high moisture content when operating in harsh environment impede their wider application. This thesis focuses on particularly energy-hungry industrial sectors characterized by presently unsolved challenges in terms of environmentally hostile low-temperature heat sources. Existing thermodynamic cycles based on Organic Rankine Cycle (ORC) are adapted and optimized for this temperature level. Two conventional heat recovery methods are studied more particularly: indirect and direct contact dehumidification. Optimized design methods for heat exchangers are elaborated and experimentally validated. For the indirect contact dehumidification, advanced anti-corrosion coated materials are proposed and laboratory tested. For the direct contact dehumidification, the effects of packing material and geometry on the corresponding hydraulic performances are underlined. Innovative thermodynamic cycles based on the liquid desiccant technology are investigated. An improved regeneration cycle (IRC) is developed. Compared to the conventional heat recovery technologies, the proposed “IRC” improves both net power and turbine expansion ratio besides preventing faced corrosions problems
Fardoun, Farouk. "Etude de la déformation plastique cyclique des aciers inoxydables austénitique, ferrique et duplex, par analyse des boucles d'hystérésis : contraintes internes et effectives". Lille 1, 1997. http://www.theses.fr/1997LIL10157.
Texto completo da fonteDuarte, Ricardo. "Elaboration et validation d'une méthode de conception d'orthèses avec mécanisme : corset de traitement de la camptocormie". Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0842/document.
Texto completo da fonteOrthosis development is often based on the empirical expertise of the manufacturers. This can sometimes result in poorly adapted devices. For this reason, some structure needs to be created for the orthosis design process.The purpose of this thesis is to develop a structured design method for orthoses with a mechanism.A typology of orthoses is established according to whether or not a mechanism is present. This typology is the starting point for producing a breakdown of the cycle of orthosis use in life situations and at significant moments.The method described here includes searching a mobility database for mechanisms; ensuring compatibility between concepts, displacement and dimensional constraints, making suitable adaptations for a comfortable fit, defining the blocking, preparing the final definition of the orthosis with mechanism and approving the design.The method is applied to the development of a corset for treating camptocormia, a postural illness identified by the gradual forward flexion of the trunk.A postural orthosis, a thoraco-pelvic anterior distraction corset developed by Lagarrigue S.A., is currently prescribed. To prove the utility of wearing the corset, a kinematic characterisation of the movement and muscle activity of the camptocormic patient is carried out both with and without the corset to collect the information needed for the design process of an innovative orthosis.Using this method two functional corset prototypes were developed to treat camptocormia, incorporating the patient’s biomechanical information and the manufacturer’s technical limitations
Gasnereau, Isabelle. "Etude du mécanisme de dégradation de la « Mitotic Kinesin like protein 2 » en sortie de mitose". Paris 6, 2008. http://www.theses.fr/2008PA066446.
Texto completo da fonteRassou, Somasoudrame. "Polymérisation anionique d’oxiranes fonctionnels selon le mécanisme de monomère activé". Electronic Thesis or Diss., Paris 6, 2016. http://www.theses.fr/2016PA066749.
Texto completo da fonteSynthesis of polyether-based polyelectrolyte containing amine functions have scarcely been studied, while this polymer family offers a large set of potential applications in the biomedical domain and in material science for energetic application. With the aim of circumventing the use of the toxic epichlorhydrin, the present subject is revisiting the anionic ring opening polymerization of a set of monomers containing a protected amine and a polymerizable oxirane function. The syntheses of the monomers were first reported through the direct oxidation of unsaturated monomers containing ech a protected amine moities. Then these monomers were polymerized by anionic ring opening polymerization. The best results were achieved with glycidylphtalimide using an activated monomer mechanism. The homopolymers conditions synthesis were extended to the synthesis of block copolymers
Brien, Valérie. "Etude par microscopie électronique en transmission des mécanismes de déformation d'un superalliage à base de nickel en fatigue oligocyclique à haute température". Paris 11, 1995. https://tel.archives-ouvertes.fr/tel-02985973.
Texto completo da fonteIn order to understand the structural mechanisms of deformation in low cycle fatigued single-crystal superalloys, total deformation imposed with R epsilon = εmin / εmax= 0 or -1, according to crystallographic axis <001> tests were carried out tests at 950 °C (1223K), at the frequency 0. 25Hz. In R epsilon = 0 fatigue, we derive a general behaviour of the microstructures of deformation according to two parameters which are the total deformation imposed and the number of cycles. Thus, a simple tension causes the localization of dislocation networks at matrix/precipitated interfaces perpendicular to <001> so that excited dislocations are those that relax the parametric deviation. The greater the total deformation imposed or the greater the number of cycles, the more homogeneous the deformation spreads out to the vertical channels. Dislocations reduce the parametric misfit between the two phases. Type N coarsening is observed at 200 cycles for small amounts of total deformation imposed. In R epsilon = -1 fatigue, we show that compression deforms the vertical channels without the formation of networks since only one deformation glide sliding system is excited. Tension always deforms the horizontal channels in the same manner as in repeated fatigue. We also show that N type coarsening (identical to that obtained in tension creep for this type of superalloy) occurs very fast, as soon as 115 cycles. The synthesis of these results, enriched with considerations on the internal stresses (coherence stresses and stresses due to parametric deviation/misfit) allowed us to propose a model of behaviour that predicts (whether in fatigue R epsilon = 0, R epsilon = -1, in tension or compression) the nature and location of the active gliding systems as well as the qualitative distribution of the internal stresses of the superalloy
Safieddine, Adham. "L'imagerie systématique de transcrits et de polysomes uniques révèle un mécanisme de transport dépendant de la protéine naissante". Thesis, Montpellier, 2019. http://www.theses.fr/2019MONTT025.
Texto completo da fonteLocal translation allows a spatial control of gene expression. Here, I participated in two mRNA localization screens imaging more than 1000 transcripts in total: (i) the first was a dual mRNA/protein screen that used a BAComics approach to co-detect mRNAs and the protein they encode; (ii) the second was done using a new high-throughput smFISH approach to screen all genes that encode centrosomal proteins and mitotic regulators. The first screen revealed cases of local translation at various subcellular compartments including cytoplasmic protrusions, centrosomes, Golgi, endosomes and the nuclear pore, which was never described before. Remarkably, translation of the nascent peptide was required for the transport of many localized transcripts. In addition, I showed that several mRNAs (such as ASPM and DYNC1H1) are translated in dedicated structures called translation factories.The second screen revealed 8 transcripts that are localized and translated at the centrosome. I showed that the localization of these 8 transcripts is regulated by the cell cycle, and that it also requires translation of the nascent polypeptide. Using the endogenous ASPM gene as a model, I imaged single mRNAs and polysomes with the MS2 and SunTag systems, respectively. This revealed a directed transport of ASPM polysomes towards centrosomes at the onset of mitosis, when this mRNA starts localizing. These data provide definitive evidence for a co-translational targeting mechanism dependent on motors as well as the nascent protein. This argues against the current dogma that mRNA transport is an RNA-based process acting on translationally repressed molecules. Instead, it suggests that SRP-like mechanisms are more widespread than previously thought
Esneu, Maryse. "Contribution à l'étude du contrôle neuroendocrinien de la stéroïdogénèse surrénalienne : effet et mécanisme d'action du CGRP". Rouen, 1997. http://www.theses.fr/1997ROUES006.
Texto completo da fonteAhmed, Hussam. "Fiabilité et cycle de vie des composants mécaniques dégradés : essais de démonstration et analyse basée sur la fonction de Hasard". Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2009. http://tel.archives-ouvertes.fr/tel-00845425.
Texto completo da fonteVirginillo, Martin Gustavo. "Méthode d'analyse du cycle de vie des emballages". Thesis, Université Laval, 2011. http://www.theses.ulaval.ca/2011/28009/28009.pdf.
Texto completo da fonteNiault, Théophile. "Étude du mécanisme de synchronisation de la réplication des deux chromosomes de Vibrio cholerae". Electronic Thesis or Diss., Sorbonne université, 2023. http://www.theses.fr/2023SORUS121.
Texto completo da fonteContrary to the vast majority of bacteria that possesses a unique chromosome, Vibrio cholerae, the pathogenic agent responsible for cholera disease, contains a genome divided into two replicons: a main chromosome (Chr1) and a secondary chromosome (Chr2). Secondary chromosomes appeared independently in many bacterial phylum and are often associated with pathogenic or symbiotic traits (i.e. Leptospira, Agrobacterium, Burkholderia). Secondary chromosomes result from the acquisition and domestication of large plasmids1. Indeed, some “megaplasmids” have cohabited with their host over a long evolutionary period and became an obligatory component of their host’s genome, essential for their normal metabolism. During their domestication, secondary chromosomes acquired different features allowing their maintenance through cell divisions ensuring their vertical transfer to subsequent generations. The study of multipartite genome bacteria allows questioning the selective benefit of an organism to possess several chromosomes. In addition, how can a horizontally acquired genetic element connect to a pre-established genetic network? One of the major steps in megaplasmid domestication is their integration into the host cell cycle. In V.cholerae, Chr2 replication is coordinated with that of Chr1. Chr1, which is 3 times larger than Chr2, is initiated first and when 2/3 has replicated, an initiation signal triggers the replication of Chr2 so that both chromosomes terminate replicating concomitantly. This initiation signal is emitted when the replication fork passes through a non-coding Chr1 locus named crtS (Chr2 Replication Triggering Site)2,3. However, the molecular mechanism behind this initiation signal is still very elusive. Our work aims to elucidate the mechanism of this novel bacterial replicative checkpoint. In order to tackle this problem we developed several cutting-edge approaches to study the mechanism at different levels: -Genomic scale: high resolution ChIPseq -Single cell: fluorescent microscopy -Molecular: CryoEM