Rozprawy doktorskie na temat „Diffusion d'hydrogène”
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Potvliege, Robert. "Etude théorique de la diffusion élastique et inélastique d'électrons et de positrons rapides par des atomes d'hydrogène". Doctoral thesis, Universite Libre de Bruxelles, 1985. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/213632.
Pełny tekst źródłaOuraou, Ahmimed. "Mesure des fonctions de structure du proton par diffusion inélastique de muons sur cible d'hydrogène et tests de la chromodynamique quantique". Paris 11, 1988. http://www.theses.fr/1988PA112118.
Pełny tekst źródłaLarbi, Fadila. "Traitement de couches minces et de dispositifs à base de a-Si : H par un plasma d'hydrogène : Etude in situ par ellipsométrie spectroscopique". Thesis, Reims, 2014. http://www.theses.fr/2014REIMS010/document.
Pełny tekst źródłaThis work is a contribution to the study of the interaction between hydrogenated amorphous silicon (a-Si:H) thin films and hydrogen plasma in a PECVD (Plasma Enhanced Chemical Vapor Deposition) reactor. The kinetics of silicon etching by atomic hydrogen is monitored in situ by UV - visble ellipsometry .Several plasma parameters (temperature, RF power, H2 gas pressure, the doping of the material) that may impact the kinetics were probed. An analysis of the spectroscopic ellipsometry spectra, thanks to an appropriate optical model, allowed evidencing their effects on the time constant, the thickness and the hydrogen excess of the H-modified layer.The same hydrogen plasma treatment repeated on i/p and i/n H base junctions revealed a particular behavior of the etching kinetics in the junction zone. This effect is interpreted in the frame of a simple of hydrogen diffusion model under an electric field
Bouachir, Mohamed. "Etude par diffusion de la lumière Rayleigh et Raman de la structure et de la dynamique moléculaire du sulfure d'hydrogène à l'état liquide". Bordeaux 1, 1985. http://www.theses.fr/1985BOR10556.
Pełny tekst źródłaKane-Diallo, Ousseynou. "Analyse morphologique des champs de cavités dans un élastomère sous décompression d'hydrogène : Influence des conditions de décompression et effets d'interaction". Thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2015. http://www.theses.fr/2015ESMA0014/document.
Pełny tekst źródłaThe morphology of cavitation is analyzed in an unfilled EPDM under different hydrogen decompression conditions. The experimental device allows a time-resolved tracking of the evolution of damage. Images are processed to obtain the onset time, the number and sizedistribution of cavities over time, and the inflation / deflation kinetics of the biggest cavities.Covariograms quantifies the spatial distribution of cavity fields. The analysis is thus led at two scales: that of independent cavities and that of the full cavity fields. At the cavity scale, kineticsis shown to be identical for independent cavities but different between inflation and deflation.Experimental kinetics is compared to that issued from Finite Element calculations in a cell containing one or two cavities, in coupled diffuso-mechanical conditions. Calculationshighlight the evolution of local mechanical and gas content fields, as well as interaction effects between close cavities. At the scale of cavity fields, the spatial distribution is influenced by the decompression conditions. The number and size of cavities increase with saturation pressure and/or decompression rate and a second population of small cavities is nucleated around the first one under severe decompression conditions. The homogeneity and isotropy of the distribution at macroscopic scale are studied. The influence of cycling on the evolution of cavitation morphology is addressed in the final part. It was finally found that the morphology of cavity fields evolves during successive cycles. The analysis provides information to discuss and to inquire the framework and ingredients of damage models
De, Iuliis Silvana. "Etude de la vitesse de formation des suies à partir de l'éthylène en présence d'hydrogène par les méthodes du tube à choc et du brûleur au moyen de différentes techniques optiques". Phd thesis, Université d'Orléans, 2009. http://tel.archives-ouvertes.fr/tel-00623053.
Pełny tekst źródłaLekbir, Choukri. "Effet de la déformation plastique du nickel monocristallin sur l'état d'équilibre de l'hydrogène en surface et subsurface". Thesis, La Rochelle, 2012. http://www.theses.fr/2012LAROS368.
Pełny tekst źródłaThe present work has for objective to study the synergy between the plastic strain and the processes of adsorption and absorption of hydrogen on the surface and the subsurface of nickel single crystal.Hydrogen Evolution Reaction (HER) and Hydrogen Absorption in subsurface (HAR) share mostly the common intermediate: the adsorbed hydrogen (Hads). The HER pathway on nickel (100) single crystal surfaces in sulphuric acid medium can be related by a Volmer-Heyrovsky mechanism. The corresponding elementary kinetic parameters as symmetry coefficients, activation enthalpies, number of active sites, have been identified via a thermokinetic model using experimental data. These parameters can be affected by defects associted with plastic strain. Irreversible plastic strain modifies the density and the distribution of storage dislocations affecting the surface roughness at atomic scale and generating additional active adsorption sites. Further more, surface emergence of mobile dislocations induces the formation of slip bands, which modify the surface roughness and the electronic state of the surface and increases the (111) surface density. The entry of hydrogen atoms associated to the transfer step surface-Subsurface can be measured using a potentiostatic double-Steptechnique (pulse method). This last allowed to characterizing the diffusion and trapping of hydrogen in the subsurface. Two domains can be distinguished, that of the subsurface and that of the bulk of the sample. In this case, the diffusion coefficient near the surface (subsurface) seems to be much higher than that obtained in the bulk of the metal. On the other hand, the application of mechanical stressleads to an increase of traps density. This last, developed near the surface: « subsurface », is lower than that at the bulk of material, which suggest a softening effect in the subsurface
Demmano, Gustave. "Réactions enzymatiques cycliques : études systématiques des modèles de transport-réaction transmembranaires d'électrons et de protons. Cycles amplificateurs multienzymatiques en solution". Rouen, 1992. http://www.theses.fr/1992ROUES027.
Pełny tekst źródłaNizeyimana, Fidèle. "Etude du vieillissement hydrolytique et thermo-oxydatif de blindages neutroniques". Phd thesis, Paris, ENSAM, 2012. http://pastel.archives-ouvertes.fr/pastel-00697087.
Pełny tekst źródłaRuffio, Emmanuel. "Estimation de paramètres et de conditions limites thermiques en conduction instationnaire pour des matériaux anisotropes". Phd thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2011. http://www.theses.fr/2011ESMA0019.
Pełny tekst źródłaThis study deals with the resolution of two types of inverse heat transfer problem: estimation of thermophysical parameters and estimation of thermal boundary conditions. A first part is devoted to the 3D-flash method which is used to estimate the three thermal diffusivities corresponding to the three principal directions of an anisotropic material. This work led to the realization of a experimental setup. The thermal excitation is provided by a CO2 laser and the temperature fields are acquired using infrared thermography. The thermal diffusivities are estimated by combining an estimator, an experiment and an analytical modeling. Different estimators are proposed and compared, based on their standard deviations. Moreover, a procedure to perform experiment design is presented to further reduce these standard deviations. In the second part, two studied cases consisting in estimating thermal boundary conditions are presented. Both underlying systems involve materials whose thermal properties are known. The thermal boundaries are estimated using temperature measurement provided by thermocouples. The first case deals with the evaluation of heat transfer between the gas and the inner-surface of a high pressure hydrogen tank. In the second case, the objective is to estimate the heat flux absorbed by a composite sample exposed to an oxygen-acetylene torch, in order to simulate the ablation phenomena under extreme conditions. Optimization algorithms are essential in this work. Gradient-based methods are used for parameters estimation and thermal boundary estimation problems. Stochastic algorithms appear to be well adapted in the framework of experiment design problems
Rossi, François-Noël. "Etude théorique des collisions non réactives entre atomes alcalins et molécules d'hydrogène ou de deuterium : Calcul et analyse des surfaces de potentiel, application aux transitions de structure fine du rubidium". Paris 13, 1986. http://www.theses.fr/1986PA132015.
Pełny tekst źródłaUlff, Nicolas. "Analyse et prise en compte des effets de l’hydrogène sur le comportement thermomécanique des AMF à base NiTi". Electronic Thesis or Diss., Université de Lorraine, 2021. http://www.theses.fr/2021LORR0308.
Pełny tekst źródłaAdvances in the many fields that form medicine have many origins, one of them being the evolution of the materials used. In particular, the rise of the intelligent materials enables to consider new technical solutions, or to significantly improve existing devices. Shape memory alloys belong to this family of intelligent materials, due to their temperature dependent behavior. Their mechanical behavior is therefore more complex compared to more well-known materials such as steels. This allows, for example, to achieve a level of reversible deformation of the order of several percent. One of the first applications of these materials concerns the field of orthodontics, with the development of orthodontic wire in NiTi shape memory alloy. Its interest is to take advantage of the application of an almost constant force during the treatment. One problem with which dentists are confronted is due to the presence of hydrogen which leads to premature rupture and degradation of NiTi wires mechanical properties during orthodontic treatments. The brittle nature of the rupture is an indication of the multi-physical origin of this issue. This PhD proposal will focus on the analysis of these hydrogen effects on the thermomechanical behavior of Shape Memory Alloys (SMAs) in order to develop a finite element model. For that end, experimental characterizations will be carried out and analysis of obtained results will allow to formulate an adapted coupled chemo-thermo-mechanical constitutive model. This behavior model will be integrated in two special finite elements (2D and 3D) with coupled degrees of freedom (thermal, mechanical and chemical degrees of freedom). These elements will be implemented in the Abaqus code via the subroutine UEL. The obtained numerical tool will allow to analyze the effect of hydrogen diffusion on the performance of SMA-based orthodontic arches. These finite element predictions will be confronted with experimental observations
Valencia, Hubert. "Applications de la chimie quantique : surfaces de molybdène nues et carburées, fonctionnalisation d'une surface carbonée (graphite ou nanotube) par un métal de transition et activation du dihydrogène". Phd thesis, Université de Poitiers, 2006. http://tel.archives-ouvertes.fr/tel-00150024.
Pełny tekst źródłaL'étude de la fonctionnalisation de surfaces carbonées - graphite et nanotube (8,0) - par un atome de métal de transition est réalisée par des calculs DFT. Il est déterminé que les atomes de Cr, Mn et Cu sont physisorbés alors que les autres atomes de la série 3d sont chimisorbés. L'occupation de l'orbitale 4s pour Cr, Mn et Cu conduit à une répulsion métal-surface, quelque soit la courbure du plan graphitique. Les surfaces d'énergie potentielle sont déterminées pour évaluer les barrières de diffusion. Sc, Ti, Fe et Co sont les métaux susceptibles d'être isolés en surface. Les autres diffusent (formation d'aggrégats). Le magnétisme, l'énergie d'adsorbtion et la structure géométrique sont analysés à l'aide de l'étude des densités d'états, des charges de Bader et de diagrammes orbitalaires de molécules organométalliques modèles.
Finalement, l'activation du dihydrogène par un métal 3d de surface est étudiée. Des complexes dihydrures et d'hydrogène moléculaire sont localisés en surface. La faible élongation de la liaison s HH est observée préférentiellement pour Fe, Co et Ni tandis que la rupture de la liaison apparaît pour Sc, Ti et V. La saturation de certains métaux par adsorption de plusieurs molécules d'hydrogène est entreprise. Il est montré que ces matériaux hypothétiques pourraient stocker l'hydrogène.
La création d'un cluster d'ordinateurs pour le calcul numérique est présentée. L'originalité consiste à utiliser des ordinateurs dédiés à l'enseignement et utilisables en dehors de ces périodes.
Leon, Vincent. "Etude des effets de confinement dans la silice mésoporeuse et dans certaines nanostructures carbonées". Phd thesis, Université d'Orléans, 2006. http://tel.archives-ouvertes.fr/tel-00107124.
Pełny tekst źródłaOuraou, Ahmimed. "Mesure des fonctions de structure du proton par diffusion inélastique de muons sur cible d'hydrogène et tests de la chromodynamique quantique". Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb376172402.
Pełny tekst źródłaBERGNES, BRASEY CHANTAL. "Etude des processus directs elastique et inelastiques se produisant lors de la collision entre un ion d'helium et une cible d'hydrogene, pour une energie variant de 1,5 a 30 kev". Toulouse 3, 1988. http://www.theses.fr/1988TOU30204.
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