WorldCat Identities

Ecole Doctorale Physique et Sciences de la Matière (Marseille)

Overview
Works: 739 works in 1,036 publications in 2 languages and 1,036 library holdings
Roles: Other, Degree grantor
Publication Timeline
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Most widely held works by Ecole Doctorale Physique et Sciences de la Matière (Marseille)
Modélisation de la liaison os-ligament dans l'articulation du genou by Damien Subit( )

2 editions published in 2004 in French and held by 3 WorldCat member libraries worldwide

Utilisation de la spectroscopie pour la standardisation des supernovae de type Ia by Jérémy Le Du( Book )

3 editions published between 2008 and 2017 in French and held by 3 WorldCat member libraries worldwide

We present in this thesis an analysis of the standardisation of Type Ia supernovae (SNela) using distant supernovae (0.2<z<1) discovered at CFHTLS (SNLS) and followed in spectroscopy at the VLT. We study spectral indicators in the CaH&K and Sill region. We evaluate in detail the correlation with the MB magnitude. We propose a new indicator, named EDCa that showq a ctrong correlation with MB. We emphasize that this parameter is strongly correclated with the photometric color parameter of the SN and almost independent of the host galaxy reddening and of the standard photometric stretch parameter. The dispersion of the corrected magnitude with EDCa ia as goog as the standard magnitude correction. Combining tha standardization parameters, we find in our sample of 50 SNela that we can imporve the SNela standardization. EDCa can be viewed as a new standardization parameter
Etude des sursauts gamma à partir des neutrinos de haute-énergie avec le télescope ANTARES : analyse du positionnement acoustique du détecteur by Gabrielle Lelaizant( Book )

3 editions published between 2008 and 2018 in French and held by 3 WorldCat member libraries worldwide

Le télescope ANTARES, déployé en mer Méditerranée à 2500 m de profondeur, est destiné à la détection de neutrinos cosmiques de haute-énergie. Le positionnement du détecteur est assuré par un système acoustique qui permet d'atteindre une précision de quelques centimètres par triangulation des distances caractéristiques des couples de modules acoustiques. Parmi les sources astrophysiques recherchées figurent les sursauts Gamma, phénomènes cataclysmiques signant la formation d'un trou noir, suscepyibles d'émettre des neutrinos détectables par ANTARES. Le développement d'une méthode d'analyse dédiée à ce type de signal est étudié dans ce travail dans un but de recherche de corrélation entre émissions gamma (détectées par des satellites) et neutrinos issus des sursauts Gamma
Quantification conformément équivariante des fibrés supercotangents by Jean-Philippe Michel( Book )

3 editions published between 2009 and 2019 in French and held by 3 WorldCat member libraries worldwide

Matériaux nanohybrides à large bande interdite : études de synthèses, propriétés et applications by Aurore Said( Book )

4 editions published between 2007 and 2017 in English and held by 3 WorldCat member libraries worldwide

My thesis consists on designing dye-functionalized ZnO nanoparticles and studying their optical and morphological properties as well as the electronic interactions between inorganic ZnO and organic dye. We produced nanohybrids based on ZnO spheres and rods via two routes: Femtosecond laser ablation in liquid medium and Solution-based chemical procedures. Spherical ZnO of few nanometers created by laser ablation reveal by photoluminescence the effect of quantum confinement due to size reduction. The hemicallysynthesized ZnO rod-growth occurs by Oswald repining and Oriented attachment as noticed by HRTEM. Optical properties of the hybrids strongly depend on ZnO shapes as well as on dye type and concentration. We were able to engineer the band gap of the small ZnO particles in the nanohybrid matrices simply upon varying the dye concentration. We showed thus the quantum confinement effect through induced charged layers in the ZnO due to the adsorbed porphyrin dye
Etude et simulation de la siliciuration du cobalt en couches ultraminces pour la microélectronique : cinétique de formation, contraintes, texture et redistribution des dopants by Roger Delattre( )

2 editions published in 2013 in French and held by 3 WorldCat member libraries worldwide

The aim of this thesis is to study the growth of CoSi2 thin films using in-situ x-ray diffraction and to model it in a commercial TCAD (Technology Computer Aided Design) simulator.. We observed that the first instant of the reaction is limited by nucleation where the CoSi2 nuclei laterally grow until their coalescence. Then, the homogeneous CoSi2 layer grows by a diffusion limited mechanism. At the end of the reaction, the CoSi source run out and decrease the CoSi2 formation rate. Kinetics of these growth behaviors has been quantified. We also observed that the thinnest CoSi2 layer of our study only the CoSi2 nuclei growth take place.Influence of dopants on the CoSi2 kinetics of formation has also been studied. Arsenic decreases the CoSi2 rate of formation. However Boron does not impact the growth of CoSi2.During CoSi2 growth, stress is monitored using x-ray diffraction showing that cobalt disilicide forms in compression.From these experimental results, we developed a TCAD model in one dimension in order to simulate the sequential growth of cobalt silicides. Kinetics of formation of CoSi2 is also in good agreement with our results.The application in two dimensions of this model reproduces the morphology of 2D silicided structures as the lack of silicide under the spacers.Redistributions of Arsenic, Boron and Phosphorus are also studied in expectation of the electrical simulation of silicided components.In this word we provide a better comprehension of the growth of cobalt disilicide used in the silicidation process. We also provide a simulation tool for the silicide formation in order to help the optimization of the SALICIDE (Self Aligned siLICIDE) process
Etude numérique de la formation de nano-agrégats créés lors de l'ablation laser à courtes impulsions by Karine Gouriet( Book )

3 editions published between 2008 and 2018 in French and held by 3 WorldCat member libraries worldwide

The aim of this work is to understand the formation and the evolution of nanoclusters produced by short pulse laser ablation. Material ablation, plume formation and its evolution are simulated from a computational model, which combines molecular dynamics (MD) method and direct simulation Monte Carlo (DSMC) technique. The influence of both cluster and gas around the cluster parameters on its evaporation and condensation processes is analysed by using MD simulations. The obtained evaporation and condensation are directly transferred to the DSMC part of our combined model. Finally, several simulations MD-DSMC of longer-time over the plume expansion demonstrate both plume dynamic and cluster evolution. Two cluster evolution mechanisms are demonstrated : by material ejection and by collision processes during plume expansion. Comparisons with experimental findings show a good agreement with the prediction for the cluster size distribution
Modélisation du comportement mécanique de la cellule et de son cytosquelette : approche basée sur la mécanique des milieux divisés by Jean-Louis Milan( )

2 editions published in 2007 in French and held by 3 WorldCat member libraries worldwide

Le comportement mécanique des cellules vivantes, qui participe au contrôle de leur activité biologique, dépend étroitement des propriétés mécaniques de leur cytosquelette (CSQ). Pour décrire la structure précontrainte et multi-modulaire du CSQ et son mode de réorganisation dynamique, j'ai développé dans le cadre de cette thèse, un modèle mécanique numérique 2D basé sur la théorie des milieux divisés : le modèle CMD (Cytosquelette - Milieux Divisés). Les systèmes de forces intracellulaires générées par les différents réseaux de filaments du CSQ sont reproduits dans le modèle CMD par des réseaux d'interactions de tension et de compression qui s'établissent entre les noeuds du milieu divisé qui compose le modèle. La particularité du modèle CMD est de proposer un mode de réorganisation dynamique du CSD, basé sur une connectivité variable des réseaux d'interactions qui se modifie pour s'adapter au chargement ; cette réorganisation permet de traduire les réarrangements locaux des filaments du CSQ en cours de déformation. Le modèle CMD reproduit le comportement de rigidification observé expérimentalement sur des cellules en cours de déformation et qui est fonction du niveau de contractilité du CSQ. De plus, les réseaux d'interactions qui se développent et s'équilibrent au sein du modèle CMD permettent d'identifier les différentes sous-structures du CSQ : le cortex, le réseau de fibres de tension connecté à la matrice extracellulaire via les points focaux d'adhésion, le réseau diffus de filaments d'actine, le réseau de filaments intermédiaires, le réseau de microtubules. La suppression d'un de ces réseaux d'interactions entraîne dans le modèle une diminution de la précontrainte et de la rigidité qui se traduit par une perte d'intégrité structurale, suggérant ainsi que les sous-structures de CSQ sont fortement interdépendantes. Au vu de ses résultats, le modèle CMD peut constituer un outil pour comprendre les processus cellulaires, qui impliquent la réorganisation du CSQ, tels que l'adhésion, la migration ou la mécanotransduction
Etude et applications de nano-structures élaborées par faisceau d'ions focalisés by Alan Reguer( Book )

3 editions published between 2009 and 2019 in French and held by 3 WorldCat member libraries worldwide

Focused ion beam (FIB), developed in the early 1970's after the development of Liquid Metal Ion Source (L.M.I.S), has recently emerged as an important technology to elaborate and to study nanostructures and nanostructure-based devices. Ions beam are now fairly routinely focused to dimensions in the nanometer range. Associated with a gas injection system (GIS), FIB is used for selective etching and deposition processes. This thesis work deals with the study of nanostructures elaborated by FIBID (Focused Ion Beam Induced Deposition). FIBID uses ion energy to initiate localized chemical vapor deposition (CVD) through the decomposition of precursor molecules adsorbed on the surface. FIBID is a maskless direct writing technique that allows the deposition of sub-micronic patterns. The fabrication by FIBID of different nano-structures and their characterization (morphology, chemical composition, microstructure and electrical properties) has allowed a better understanding of the deposition process. These results have opened a wide range of applications for the FIBID technique in the field of nano electro-mechanical systems (NEMS). We present a method that allows in situ localized heating simultaneously with real time scanning and transmission electron microscopy studies. The localized heating is induced by flowing current through conductive nanowire deposited by FIBID on a 50nm thick Si3N4 membrane. Gold nanoparticles are used as thermometers for probing the local temperature of the heated Si3N4 membrane and to determine the temperature profile around the nanowire by applying a finite element analysis. These conductive nanowires are also used to initiate the synthesis of silicon nanowires by VLS (Vapor-Liquid-Solid) mechanism using Au or Ga as catalyst solvent. We have followed, in a scanning electron microscopy (SEM), the nucleation and the growth of Si NWs and demonstrate that two different growth mechanisms are obtained depending on the catalyst solvent (Au or Ga)
Détermination expérimentale des caractéristiques physiques et chimiques de particules de suie émises par des turboréacteurs d'avion by David Delhaye( Book )

3 editions published between 2007 and 2018 in French and held by 3 WorldCat member libraries worldwide

Les émissions liées à la combustion de la biomasse et des carburants fossiles constituent des sources significatives de particules dans l'atmosphère. Les particules de suie émises par les turboréacteurs aéronautiques dans la basse stratosphère et la haute troposphère, zones sensibles de l'atmosphère, ont un impact sur le forçage radiatif global de par la formation de traînées de condensation qui peuvent évoluer en nuage de type cirrus. Par ailleurs, ces particules de taille submicrométrique, dont l'impact sur la qualité de l'air est avéré, sont également source de questionnement quant à leur(s) effet(s) sur la santé publique. La présente étude a pour objet la détermination expérimentale des caractéristiques physiques et chimiques des particules de suie émises par des turboréacteurs d'avions commerciaux. Les prélèvements sont effectués sur un banc d'essai de la société SNECMA (groupe SAFRAN) par un dispositif mis au point au cours de ce travail et localisé derrière des turboréacteurs CFM56-5C et CFM56-5B qui équipent respectivement des avions long-courriers et moyen-courriers. Diverses techniques expérimentales telles que la microscopie électronique en transmission (MET), la microscopie électronique à balayage (MEB), la spectrométrie dispersive d'énergie de rayons X (XREDS), et la spectroscopie infrarouge à transformée de Fourier (IRTF) sont mises en œuvre pour étudier la morphologie, la structure, la distribution en taille, la composition chimique élémentaire des particules primaires de suie, et la nature des groupes fonctionnels présents à leur surface. La dimension fractale ( ) des agrégats de suie et leur diamètre de giration ( ) sont également établis. Les résultats expérimentaux montrent que les suies émises par les deux turboréacteurs étudiés présentent : - des valeurs similaires de la dimension fractale des agrégats - des distributions en taille log-normales pour les particules primaires et les agrégats - des compositions chimiques élémentaires et des groupes fonctionnels très similaires - des diamètres de giration des agrégats qui diffèrent Par ailleurs, nous montrons que la phase de préparation des échantillons, préalable aux observations en MEB, a une influence importante sur la valeur déterminée de la moyenne géométrique de la distribution en taille des particules primaires. Par conséquent, nous préconisons de réaliser l'étude des caractéristiques physiques des particules primaires de suie aéronautique par MET plutôt que par MEB
Hamiltonian Perturbation Methods for Magnetically Confined Fusion Plasmas by Natalia Tronko( )

1 edition published in 2010 in English and held by 2 WorldCat member libraries worldwide

This thesis deals with dynamicla investigation of magnetically confined fusion plasmas by using Lagrangian and Hamilton formalisms. It consists of three parts. The first part is devoted to the investigation of barrier formation for the EXB drift model by means of the Hamiltonian control method. The strong magnetic field approach is relevant for magnetically confined fusion plasmas ; this is why at the first approximation one can consider the dynamics of particles driven by constant and uniform magnetic field. In this case only the electrostatic turbulence is taken into account. During this study the expressions for the control term (quadratic in perturbation amplitude) additive to the electrostatic potential, has been obtained. The effeciency of such a control for stopping turbulent diffusion has been shown analytically abd numerically. The second and the third parts of this thesis are devoted to study of self consistent phenomena in magnetized plasmas through the Maxwell-Vlasov model. In particular, the second part of this thesis treats the problem of the monumentum transport by derivation of its conservation law. the Euler-Poincare variational principle (with constrained variations) as well as Noether's theorem is apllied here. this derivation is realized in two cases : first, in electromagnetic turbulence case for the full Maxwell-Vlasov system, and then in electrostatic turbulence case for the gyrokinetic Maxwell-Vlasov system. Then the intrinsic mechanisms reponsible for the intrinsic plama rotation, that can give an important in plasma stabilization, are identified. The last part of this thesis deals with dynamicla reduction for the Maxwell-Vlaslov model. More particularly; the intrisic formulation for the guiding center model is derived. Here the term 'intrinsis" means that no fixed frame was used during its construction. Due to that not any problem related to the gyrogauge dependence of dynamics appears. The study of orbits of trapped particles is considered as one of the possible for illustration of the first step of such a dynamical reduction
Three dimensional X-ray Bragg ptychography of an extended semiconductor heterostructure by Anastasios Pateras( )

2 editions published in 2015 in English and held by 2 WorldCat member libraries worldwide

Ptychography is a coherent diffraction imaging technique which aims in retrieving the lost phase from intensity-only far-field measurements. The versatility of the approach has proved an important asset for 3D mapping of different physical quantities, like the electron density of micrometer-sized specimens with resolution in the 10 - 100nm range. In this work, we explored the possibility to push further the current limits of 3D Bragg ptychography, by addressing the case of an extended InP/InGaAs nanostructured thin film, bonded on a silicon wafer. The experiment was performed at the ID13 beamline at ESRF, with a monochromatic beam focused down to 100nm. 2D intensity patterns were acquired at several incidence angles in the vicinity of the InP (004) Bragg peak, stacking up a three dimensional dataset. Numerical analysis of the given problem was performed beforehand in order to optimize the inversion strategy and study the possibility of introducing additional physical constraints through regularization approaches. Inversions of the dataset were done using a ptychographical gradient-based optimization phase retrieval algorithm. The developed strategy was applied on the experimental data which led to the retrieval of a complex-valued 3D image. The result exhibits the high crystallinity quality of the sample with the expected values of thickness and lattice mismatch, nevertheless, small local lattice tilts have been observed - in the order of 0.02°- and confirmed by numerical modeling. This result demonstrates the high sensitivity of the technique, as well as its exciting perspectives for imaging complex organic and inorganic nanostructured materials
Terme constant de fonctions sur un espace symétrique réductif p-adique by Nathalie Goldman Lagier( Book )

2 editions published in 2018 in French and held by 2 WorldCat member libraries worldwide

We generalize Casselman's pairing to p-adic reductive symmetric spaces and study the asymptotic behaviour of certain generalized coefficients. We also prove an analogue of a lemma due to Langlands which allows us to prove a disjunction result for the Cartan decomposition of the p-adic reductive symmetric spaces
Application de la radiographie X synchrotron à la caractérisation de la microstructure de solidification d'alliages métalliques by Abdoul-Aziz Bogno( Book )

2 editions published in 2011 in French and held by 2 WorldCat member libraries worldwide

Une étude expérimentale systématique de la formation des microstructures de solidification d'alliages métalliques (Al-Cu) a été effectuée par application de la radiographie X synchrotron. La radiographie X-Synchrotron nous a donné accès à des observations in situ et en temps réel qui nous ont permis d'analyser de manière quantitative les phénomènes physiques impliqués au cours de la solidification (vitesse de croissance, redistribution du soluté, interaction entre grains équiaxes etc.). Elle nous a également permis de mettre en évidence l'influence de la convection naturelle et de la gravité sur ces différents paramètres physiques et par conséquent sur la formation de la microstructure de solidification. Nous avons comparé nos résultats expérimentaux avec des modèles de prédiction de la croissance dendritique et ensuite avons montré l'intérêt des expériences en microgravité. Nous avons enfin effectué des séries de tests du dispositif expérimental conçu et développé par SSC (Swedish Space Corporation) dans le cadre du projet XRMON (In situ X-Ray MONitoring of advanced metallurgical processes under microgravity and terrestrial conditions) de l'ESA-MAP en vue d'une expérience in situ et en temps réel de solidification en microgravité à bord d'une fusée sonde Maser12. Cette expérience prévue en Novembre 2011. Les résultats obtenus lors des séries de tests valident le dit dispositif en termes de comportement thermique et d'imagerie X par radiographie
Analyse quantitative d'images de phase obtenues par interféromètrie à décalage quadri-latéral. Applications en biologie by Sherazade Aknoun( Book )

2 editions published in 2014 in French and held by 2 WorldCat member libraries worldwide

The aim of this thesis, dedicated to the study and quantitative analysis of phase images obtained thanks to quadri-wave lateral shearing interferometry, is to caracterize a metrological tool and its three proposed different applications.This work has been done in collaboration between Institut Fresnel (Marseille, France) and Phasics company (Palaiseau, France) and continues that of Pierre Bon who has been in charge the application this technique to microscopy. This interferometric technique, developped by Phasics, for optical metrology and lasers characterization, allows to record complex eletromagnetic field maps thanks to a wave front measurement. By using it in the microscope image plane, one can obtain inetnsity and optical path difference images of a semi-transparent biological sample. this technique is now considered as a new quantitative phase contrast technique.The first part of this manuscript will be a state of the art of quantitative microscopy techniques. The issues of quantification and its meanings in the framework of different fluorescent and phase based techniques will be discussed.A description of the technique that is used and its comparison with similar phase techniques will be done.The measurement, under the projective approximation, is studied leading to different variables. We show different applications concerning isotropic elements in a first part and anisotropic elements in the second one.We show how this measurement is trnasposed to the third dimensions allowing three dimensional imaging and complete reconstruction of refractive index maps of biological samples
Nanolithographie catalytique par microscopie à force atomique : étude des paramètres physico-chimiques by Vincent Mesquita( )

2 editions published in 2016 in French and held by 2 WorldCat member libraries worldwide

Lithography processes are widely used in the microelectronics industry for the realization of functional materials of nanometric size. To obtain components increasingly small (<100 nm) the development of new manufacturing processes is requires. The research presented in this thesis concerns the study of a new concept of lithography by Atomic Force Microscopy (AFM). The main objective is to use the tip of an AFM as a tool to promote catalysed reactions on a well defined zone of a grafted surface. In this way, diverse molecules could be grafted selectively and spatially to form three dimensioned objects. To better understand the reaction mechanism, different physico-chemical parameters were studied in the first part: the scanning speed of the tip, the strength applied, the interline spacing during the engraving pattern, the width lines limits, the life time of the catalytic tip and the influence of the catalyst flexibility coated to the tip. The second part consists in the realization of nanostructures with molecules that have particular physico-chemical properties (optical, electric, catalytic) and the construction of three-dimensional nanostructures. Some pertinent results are the achievement of line width of 25 nm, a minimum grafted surface of 480 µm² and the formation of a structure of pyramidal shape constituted of three different molecular levels
Théories de jauge et connexions généralisées sur les algébroïdes de Lie transitifs by Cedric Fournel( Book )

2 editions published in 2013 in English and held by 2 WorldCat member libraries worldwide

Transitive Lie algebroids are usually studied from the point of view of the geometry of Poisson. Here, they are preferentially defined in terms of sections of fiber bundle in order to get close to the formalism of the gauge field theory. Then, transitive Lie algebroids can be seen as a generalization of vector fields on the base manifold. This PhD thesis is concerned with the study of generalized connections on transitive Lie algebroids and the construction of gauge theories. Ordinary connections on transitive Lie algebroids are defined as the subset of 1-forms on Lie algebroids with values in its kernel which fulfill a normalization constraint on this kernel. By relaxing this constraint, we build the space of generalized connection 1- forms. Using a background connection, we show that any generalized connections can be decomposed as the sum of an ordinary connection and a purely algebraic parameter defined on the kernel. As in Yang-Mills theories, we define a gauge invariant functional action as the “norm” of the curvature associated to a generalized connection. Then, the Lagrangian associated to this action forms a Yang-Mills-Higgs type model composed with the field strength associated to gauge fields and a minimal coupling with a tensorial scalar field embedded into a quartic potential. In the case of Atiyah Lie algebroids, the symmetry group of the theory can be reduced by using an appropriate rearrangement of the degrees of freedom in the functional space of fields. We thus obtain a Yang-Mills type theory describing massive vector bosons
Etude des phénomènes d'absorption laser en régime femtoseconde pour l'ablation de matériaux diélectriques by Maxime Lebugle( Book )

2 editions published in 2013 in French and held by 2 WorldCat member libraries worldwide

This thesis concerns femtosecond laser absorption in dielectrics in the context of micromachining processes of glass materials. Prospected applications of this technology are optical component micro-fabrication, smart glass manufacturing, or photovoltaic cell patterning. In this context, we focus on the characterization in time and space of the absorption mechanisms occurring at the surface of irradiated dielectric materials (fused silica and sapphire). Using near-IR ultrashort pulses (30 - 450 fs) laser energy coupling efficiency for material ablation is studied at mid-intensities (1-100 TW/cm²) through two experiments. A pump-probe scheme determines the electron-hole plasma dynamics at femtosecond timescale and a laser depletion experiment measures the material absorption. A morphological study of the samples is performed, evaluating the damage and ablation thresholds as well as ablation morphologies. We then establish an energy balance of laser absorption responsible of matter removal. Typical energy densities reached are estimated through experiments and confronted to a propagative model. It is shown that the amount of absorbed energy is far above the bonding energy of the material at rest, suggesting that the major part of the absorbed energy is spent to heat the free electron gas. Finally, we propose a technological analysis of the experimental data. The interest of sub-100 fs laser pulses for photonic processes is evidenced, however at the cost of additional complexity. It provides guidelines for efficient direct laser ablation, making the results relevant for femtosecond processes
Etude et construction d'un tomographe TEP/TDM pour petits animaux, combinant modules phoswich à scintillateurs et détecteur à pixels hybrides by Stanislas Nicol( Book )

2 editions published in 2010 in French and held by 2 WorldCat member libraries worldwide

The pathway that has been followed by the imXgam team at CPPM was to combine on a single rotating device the detector modules of the small animal PET scanner ClearPET witha photon counting X-ray detector in order to perform simultaneous acquisition of images from the anatomy (X-ray CT) and from the metabolic function (PET) of the common field-of-view.A preliminary study of the hybrid imaging system ClearPET/XPAD3 carried out using Gateled us to form a new PET detection assembly based on 21 phoswich modules, to fix the design of the PET/CT device, as well as to study and solve the difficulties arising from simultaneous hybrid imaging. Last but not least, the simulation tool also allowed us for thinking how wellsuch a system could judiciously use the spatial and temporal correlations between anatomicand functional information.From an instrumentation point of view, we succeeded to set up the ClearPET/XPAD3 prototype.Once both imaging systems were operational individually, we demonstrated on one sidethat the ClearPET prototype was perfectly capable of performing correctly in simultaneousacquisition conditions, providing that the detector modules were appropriately shielded. Onthe other side, the new generation of the hybrid pixel camera using the XPAD3-S chip provedto be quite promising given the good quality of the first reconstructed images.Finally, the proof of concept of simultaneous PET/CT data acquisition was made using a sealed positron source and an X-ray tube
Echanges de masse et de chaleur entre deux phases liquides stratifiées dans un écoulement à bulles by Céline Lapuerta( Book )

3 editions published in 2006 in French and held by 2 WorldCat member libraries worldwide

Lors d'un hypothétique accident majeur dans un réacteur à eau sous pression, la dégradation du coeur peut produire un bain stratifié, traversé par un flux de bulles. Ce dernier influence grandement les transferts thermiques, dont l'intensité est déterminante dans le déroulement de l'accident. Dans ce contexte, ce travail porte sur une modélisation de type interface diffuse pour l'étude d'écoulements incompressibles, anisothermes, composés de trois constituants non miscibles, sans changement de phase. Dans les méthodes à interface diffuse, l'évolution du système est décrite à travers la minimisation d'une énergie libre. L' originalité de notre approche, inspirée du modèle de Cahn-Hilliard, réside dans la forme particulière de l'énergie que nous proposons, qui permet d'avoir un modèle algébriquement et dynamiquement consistant, au sens suivant : d'une part, l'énergie libre triphasique coïncide exactement avec celle du modèle de Cahn-Hilliard diphasique quand seulement deux des phases sont présentes ; d'autre part, si une phase est initialement absente alors elle n'apparaîtra pas au cours du temps, cette dernière propriété étant stable vis à vis des erreurs numériques. L'existence et l'unicité des solutions faibles et fortes sont démontrées en dimension 2 et 3 ainsi qu'un résultat de stabilité pour les états métastables.La modélisation d'un système ternaire en écoulement anisotherme est ensuite poursuivie par couplage des équations de Cahn-Hilliard avec celles du bilan d'énergie et de Navier-Stokes où les contraintes surfaciques sont prises en compte à travers des forces volumiques capillaires. L'ensemble est discrétisé en temps et en espace de façon à préserver les propriétés du problème continu (conservation du volume, estimation d'énergie). Différents résultats numériques sont présentés, depuis le cas de validation de l'étalement d'une lentille entre deux phases jusqu'à l'étude des transferts de masse et de chaleur à travers une interface liquide/liquide traversée par une bulle ou un train de bulles
 
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Alternative Names
ED 352

ED352

Languages
French (39)

English (9)