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École doctorale Sciences physiques mathématiques et de l'Information pour l'ingénieur (Saint-Etienne-du-Rouvray, Seine-Maritime / ....-2016)

Overview
Works: 258 works in 340 publications in 2 languages and 347 library holdings
Roles: Other, 996
Publication Timeline
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Most widely held works by Seine-Maritime / ....-2016) École doctorale Sciences physiques mathématiques et de l'Information pour l'ingénieur (Saint-Etienne-du-Rouvray
Approximation par éléments finis, analyse a posteriori et simulation de coques anisotropes by Imen Laribi( Book )

2 editions published in 2014 in French and held by 3 WorldCat member libraries worldwide

The aim of this work is to propose the a posteriori error estimator of a finite element discretization. These estimators are particulary used to have a mesh adaptivity for a Naghdi's problem for anisotropic shell model with little regularity. In a first step, we propose an existence and uniqueness result of the anisotropic Naghdi solution. We introduce a mixed formulation on a relaxed functional space with an orthogonality constraint. We prove, also, the existence and uniqueness of the solution for continuous and discrete mixed problems. Then, we propose the a posteriori analysis that leads to the construction of error indicators which satisfy optimal estimates that we use to describe a mesh adaptivity strategy. Finally, we present a constraint-free formulation of the Naghdi's problem without any orthogonality constraint that enables us, in particular, to approximate by conforming finite elements the solution with less degrees of freedom instead of the one introduced previously. We formulate the error estimator in terms of quantities of interest and in particular the upper and lower bounds on the error. Numerical tests are given that validate and illustrate our approach
Approximate hedging with transaction costs and Leland's algorithm in stochastic volatility markets by Huu-Thai Nguyen( Book )

2 editions published in 2014 in English and held by 3 WorldCat member libraries worldwide

This thesis studies the problem of approximate hedging with constant proportional transaction costs in stochastic volatility models in different situations, using a simpler form for adjusted volatility in the Leland's algorithm. We show that asymptotic properties of hedging error are the same to those in deterministic volatility models and the rate of convergence can be impoved by controlling the model parameter. These can be extended to the case where transaction costs are defined by a general rule. We also show that jumps appear in asset price and/or in stochastic volatility do not affect asymptotic property of hedging error. In the next part, we consider the problem of approximate hedging in the presence of liquidity risks suggested by Cetin, Jarrow and Protter, of which proportional transaction costs models are a particular case. We show that liquidity costs due to smooth supply surves can be ignored using Leland's increasing volatility principle. In the third part, we study the case where the option is written on multiple risky assets. We demonstrate that approximately complete replication can be reached for exchange options using the same parameter suggested by Leland, but it is far from being obvious for other kinds of exotic options. Finally, we propose a simple method to reduce the option price which clearly approaches to the super hedging price in Leland's algorithm. whenever the seller accepts to take a risk defined by a given significance level
Large comportement au temps large de l'équation de Prandtl et des systèmes de magnétohydrodynamique by Xu Zhang( Book )

2 editions published in 2016 in English and held by 3 WorldCat member libraries worldwide

This thesis is made up of two parts. One is about the long time wellposedness of Prandtl equations with monotonicity assumption. The other one is the study of global solutions for inhomogeneous Magnetohydrodynamics system with bounded positive density. Recently, under the monotonic assumption, by using the energy method, Alexandre-Wang-Xu-Yang and Masmoudi-Wong have obtained the local in time existence of smooth solution in Sobolev space for Prandtl boundary layer equation, but the life span of their solution are very small. On the meantime, Xin-Zhang proved the global-in-time weak solution by Crocco transformation under monotonicity and favorable pressure assumption. The long time behavior of the Prandtl equations is important to make progress towards the inviscid limit of the Navier-Stokes equations. With this motivation, in the first part of this thesis, we study the long time well-posedness for the nonlinear Prandtl boundary layer equation on the half plane. We consider a class of the initial data as perturbations around a monotonic shear profile and we prove the existence, uniqueness and stability of solutions in weighted Sobolev space, whose life span can be arbitrarily long while the initial perturbations are small enough. We use the energy method to prove the existence of solutions by a parabolic regularizing approximation. The nonlinear cancellation properties of Prandtl equations under the monotonic assumption are the main ingredients to establish a new energy estimate. The second part of this thesis is about global well-posedness of inhomogeneous magnetohydrodynamics(MHD) system. Recently, Danchin-Mucha have obtained well posedness of inhomogeneous Navier-Stokes equation while the density could be discontinuous by using Lagrangian transformation, or the material derivative. We will prove the global well-posedness of inhomogeneous MHD system while the density just has a positive lower bound and the initial magnetic field contains large oscillations. We first get the à priori estimate in Euler coordinate and then prove the local-in-time well-posedness of inhomogeneous MHD system in Lagrangian coordinate. Moreover, local solutions become global if the usual H1 norm of velocity and L2\L4 norm of magnetic field are small enough. Here, the smallness assumptions are different on initial velocities and initial magnetic fields. Moreover, we don't need to demand gradient of magnetic field to be small enough as that of velocities. So the initial magnetic filed can contain large oscillation
Contribution à l'étude des transformations CR des structures de Cauchy-Riemann analytiques réelles by Jean-Charles Sunyé( Book )

2 editions published in 2010 in French and held by 3 WorldCat member libraries worldwide

Cette thèse est consacrée à l'étude de l'existence d'applications holomorphes entre des sous-variétés réelles dans des espaces complexes. On s'intéresse plus particulièrement à la convergence et à l'approximation à la Artin d'applications formelles entre sous-variétés réelles. Tout d'abord, on montre la convergence des applications formelles de jacobien non identiquement nul entre une sous-variété générique analytique réelle minimale et une sous-variété générique analytique holomorphiquement non-dégénérée. Grâce à ce résultat, on obtient la convergence de toutes les applications formelles entre une hypersurface analytique réelle minimale non dégénérée et une hypersurface qui ne contient pas de courbe holomorphe. D'autre part, on établit la convergence de l'application de réflexion associée à une application formelle de jacobien non identiquement nul entre hypersurfaces lorsque l'hypersurface source est minimale. Cela nous permet ensuite de montrer un résultat d'approximation à la Artin dans ce même cas. Pour finir, on prouve un théorème artinien pour des applications CR de classe C∞ entre deux sous-variétés dans des espaces complexes de dimensions différentes
Marches au hasard sur des graphes géométriques aléatoires engendrés par des processus ponctuels by Arnaud Rousselle( Book )

2 editions published in 2014 in French and held by 3 WorldCat member libraries worldwide

Random walks on random graphs embedded in Rd appear naturally in problems arising from statistical mechanics such that the description of flows, molecules or heat diffusions in random and irregular environments. The general idea is to extend known results for random walks on Zd or on random perturbations of the grid to results for random walks on graphs generated by point processes in Rd. In this thesis, we consider nearest neighbor random walks on graphs depending on the geometry of a random infinite locally finite set of points. More precisely, given a realisation of a simple stationary point process in Rd, a connected infinite and locally finite graph G is constructed. This graph is then possibly equipped with a conductance function C, that is a positive function defined on its edge set. Examples of graphs studied in this manuscript are the Delaunay triangulation, the Gabriel graph, the creek-crossing graphs and the skeleton of the Voronoi tiling generated by the point process. We study properties of the simple random walk or of a random walk associated with the conductance C on such graphs. The main results concern the characterisation of the recurrence or transience of the random walks and the description of their diffusive scaling limits. Under suitable assumptions on the underlying point process and the conductance function, we show that the random walks on the Delaunay triangulation, the Gabriel graph and the skeleton of the Voronoi tiling generated by almost every realisation of the point process are recurrent if d = 2 and transient if d ≥ 3 . We state an annealed invariance principle for simple random walks starting from the origin on the Delaunay triangulation, the Gabriel graph and the creek-crossing graphs generated by Palm measures of suitable point processes. Finally, we show a quenched invariance principle for simple random walks on random Delaunay triangulations. This thesis uses tools from both stochastic geometry (point processes, Palm measures, random graphs ...) and the theory of random walks (links with electrical networks theory, the environment seen from the particle,...)
Nouveau matériau biodégradable et absorbeur d'oxygène à base d'amidon et de polycaprolactone. Evolution des propriétés en fonction de l'humidité by Angélique Mahieu( Book )

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

The properties of a thermoplastic starch matrix (TPS) have been characterized, in particular their variations with humidity. TPS has been mixed with Polycaprolactone (PCL), an hydrophobic polyester, in order to limit the material sensibility to humidity. A PCL of low molar mass (37000 g/mol, PCL37) and a low extrusion speed favor the PCL migration on the film surface but the material is heterogeneous. On the contrary, with a PCL of higher molar mass (50000 g/mol, PCL50) and a higher shearing rate, the repartition of the blend both phases is fine and homogeneous. An inversion of phase continuity is observed near 50% of PCL50. Interactions as hydrogen bonds between PCL and starch have been highlighted. PCL50 addition limits starch crystalline structure variations with humidity as well as water sorption of TPS phase on high water activities (>0.8). Films mechanical resistance increases in proportion to PCL rate. Their elongation at break is improved thanks to uniaxially orientation at the end of the extruder. An oxygen scavenging capacity is given to these materials by active agent addition. The film will so contribute to prolong the shelf-life of food in the case of a use as food packaging. The film containing 15% of ascorbic acid and 1.5% of iron absorbs the expected quantity of oxygen in 15 days at 85% relative humidity. This film mechanical resistance is low but the addition of 20% of PCL50 allows compensating this drawback in spite of slower oxygen absorption
Volumes finis et solutions renormalisées, applications à des systèmes couplés. by Sarah Leclavier( )

2 editions published in 2017 in French and held by 2 WorldCat member libraries worldwide

On s'intéresse dans cette thèse à montrer que la solution approchée, par la méthode des volumes finis, converge vers la solution renormalisée de problèmes elliptiques ou paraboliques à donnée L1. Dans la première partie nous étudions une équation de convection-diffusion ellliptique à donnée L1. En adaptant la stratégie développée pour les solutions renormaliséesà la méthode des volumes finis, nous montrons que la solution approchée converge vers l'unique solution renormalisée.Dans la deuxième partie nous nous intéressons à un problème parabolique nonlinéaire à donnée L1. En utilisant une version discrète de résultats de compacité classiques, nous montrons que les résultats obtenues dans le cas elliptique restentvrais dans le cas parabolique. Dans la troisième partie nous montrons des résultats similaires pour une équationparabolique doublement non-linéaire à donnée L1. Le caractère doublement nonlinéaire de l'équation crée des difficultés supplémentaires par rapport à la partie précédente, notamment car la règle de dérivation en chaîne ne s'applique pas dansle cas discret. Enfin, dans la quatrième partie, nous utilisons les résultats établis précédemment pour étudier un système de type thermoviscoélasticité. Nous montrons que la solution approchée, obtenue par un schéma éléments finis-volumes finis, converge vers une solution faible-renormalisée du système
Quantification et distribution du bore dans le silicium implanté by Huiyuan Wang( Book )

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

Ce travail de thèse est constitué de trois grandes parties. Dans la première partie, nous avons étudié théoriquement l'influence de la température sur le flux de germination de précipités dans un alliage binaire sursaturé. La théorie plus élaborée de Zeldovich a montré que le flux de germination présente un seul maximum en fonction de la température, ce qui est similaire que la théorie classique de Volmer-Weber. Une comparaison entre ces deux théories a montré que les effets de régression (dissolution possible des germes surcritiques dans une petite zone autour de la taille critique) ont une forte influence sur la forme de la courbe du flux de germination en fonction de la température. Nous avons appliqué cette étude théorique dans le système Si-B. Due à la grande énergie d'activation pour la diffusion du B dans le Si, l'étude a montré une très faible influence des effets de régression, se traduisant par une légère diminution de la température donnant le maximum du flux de germination dans le système Si-B. Dans la deuxième partie, la spectrométrie de masse d'ions secondaires (SIMS), la spectroscopie des pertes d'énergie des électrons couplée à la microscopie électronique en transmission en balayage (STEM-EELS) et la sonde atomique tomographique (SAT) ont été combinées pour la quantification du B dans le Si implanté à hautes concentrations. Leurs points forts et points faibles ont été montrés dans la caractérisation du B dans le Si. S'agissant la détection des évènements multiples dans la SAT, une nouvelle méthode du traitement des signaux de détection a été appliquée. Un progrès important concernant la quantification du bore dans le silicium a été démontré par nos expériences. Dans la troisième partie, nous avons étudié la précipitation du B dans le Si faiblement sursaturé et très sursaturé. Les études de la précipitation du B dans le Si faiblement sursaturé nous ont montré qu'il est très difficile d'étudier la précipitation seule dans le silicium faiblement sursaturé du fait de la présence des défauts d'implantation (boucles de dislocation...). Pour privilégier la précipitation, l'étude de la précipitation du B dans le Si très sursaturé a montré qu'il y a séparation de phases après implantation. À faible budget thermique, la composition des précipités est loin de celle de la phase d'équilibre SiB3, mais s'en rapproche à haute température, un régime de décomposition spinodale Si-B est suspecté pour les alliages les plus concentrés
L'Apprentissage automatique : de la sélection de variables à l'apprentissage de structure d'un classifieur bayésien by Heni Bouhamed( Book )

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

The work developed in the framework of this thesis deals with the problem of processing large amounts of data in machine learning model from an examples' database. Thus, the model constructed will serve as a tool for classifying new cases. We will particularly focus firstly, to the concept of variable selection by presenting its major strategies and propelling their shortcomings, in fact, a new filter method will be developed in this work in the aim to remedy to the identified shortcomings. Secondly, we will study the super exponential increase problem of the computational complexity of learning Bayesian classifier structure in the case of using general algorithms with no special restrictions. Indeed, referring to the formula of Robinson (Robinson, 1977), it is certain that the number of the directed acyclic graph (DAG) increases with a super exponential manner according to the increase of variables numbers. So, it is proposed in this work to develop a new approach in the aim to reduce the number of possible DAG in learning structure, without losing information. Obviously, reducing the number of DAG as possible will reduce the computational complexity of the process and therefore reducing the execution time, which will allow us to model grater information systems with the same quality of exploitation
Wavelet-based lifting structures and blind source separation : applications to digital in-line holography by Jamel Hattay( Book )

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

The present thesis is meant to develop specific processes, in the realm of wavelets domain, for certain digital holography applications. We mainly use the so-called blind source separation (BSS) techniques to solve numerous digital holography problems, namely, the twin image suppression, real time coding and transmission of holograms. Firstly, we give a brief introduction to in-line configuration of digital holography in flow measurements: the recording step explanation and the study of two reconstruction approaches that have been used during this thesis. Then, we emphasize the two well known obstacles of digital holograms reconstruction, namely, the determination of the best focus plane and the twin image removal. Secondly, we propose a meticulous scrutiny of the tool, based on the Blind Source Separation (BSS), enhanced by a multiscale decomposition algorithm, which enables the blind separation of convolutively mixed images. The suggested algorithm uses a wavelet-based transformer, called Adaptive Quincunx Lifting Scheme (AQLS), coupled with an appropriate unmixing algorithm. The resulting deconvolution process is made up of three steps. In the first step, the convolutively mixed images are decomposed by AQLS. Then, separation algorithm is applied to the most relevant component to unmix the transformed images. The unmixed images are, thereafter, reconstructed using the inverse of the AQLS transform. In a subsequent part, we adopt the blind source separation technique in the wavelet field domain to solve several problems related to digital holography. In this context, we present two main contributions for digital in-line hologram processing. The first contribution consists in an entropy-based method to retrieve the best focus plane, a crucial issue in digital hologram reconstruction. The second contribution consists in a new approach to remove a common unwanted artifact in holography called the twin image. The latter contribution is based on the blind source separation technique, and the resulting algorithm is made up of two steps: an Adaptive Quincunx Lifting Scheme (AQLS) based on the wavelet packet transform and a statistical unmixing algorithm based on Independent Component Analysis (ICA) tool. The role of the AQLS is to maximize the sparseness of the input holograms. Since the convolutive formalism is retained in digital in-line holography, BSS-based tool is extended and coupled with wavelet-based AQLS to fulfill the deconvolution task. Experimental results confirm that convolutive blind source separation is able to discard the unwanted twin image from digital in-line holograms. The last of this part consists in measuring the thickness of a ring. This ring is obtained from an improved reconstructed image of an hologram containing a vapor bubble created by thermal coupling between a laser pulse and nanoparticles in a droplet of a liquid. The last part introduces the Tele-Holography concept. Once the image of the object is perfectly reconstructed, the next objective is to code and transmit the reconstructed image for an interactive flow of exchange between a given laboratory, where the holograms are recorded, and a distant partner research. We propose the tele-holography process that involves the wavelet transform tool for lossless compression and transmission of digital holograms. The concept of tele-holography is motivated by the fact that the digital holograms are considered as a 2D image yielding the depth information of 3D objects. Besides, we propose a quincunx embedded zero-tree wavelet coder (QEZW) for scalable transmission. Owing to the transmission channel capacity, it reduces drastically the bit rate of the holography transmission flow. A flurry of experimental results carried out on real digital holograms show that the proposed lossless compression process yields a significant improvement in compression ratio and total compressed size. These experimentations reveal the capacities of the proposed coder in terms of real bitrate for progressive transmission
Synthesis of state estimation and H∞ predictive control for networked control systems by Yi-Ming Zhang( Book )

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

Cette thèse traite principalement du contrôle des systèmes en réseau. Ces derniers présentent des désagréments relatifs aux paquets d'information transportés, tels que les retards induits par le réseau, des ordres d'arrivée aléatoires voire des pertes potentielles de paquets, que ce soit dans la chaîne directe et/ou dans la chaîne de retour. La contribution de cette thèse est double : il s'agit (i) de synthétiser une loi de commande et (ii) d'élaborer un algorithme d'estimation robuste palliant tous deux à ces problèmes. Une commande prédictive généralisée basée sur l'état du système est ainsi proposée. Par comparaison avec les approches de la littérature, elle permet de compenser un plus grand nombre de pertes de paquets. La contribution principale réside dans la résolution du problème de stabilité de la commande prédictive généralisée face à un niveau de perturbation donné. Concernant l'estimation d'état, une approche basée sur le filtrage de Kalman est proposée, avec un buffer sur la chaîne de mesures et une stratégie d'élimination des mesures dont le retard est supérieur à la taille du buffer. A partir d'inégalités matricielles linéaires et d'équations de Ricatti modifiées, une relation mathématique liant la convergence de l'estimateur au taux d'arrivée des paquets de mesures est obtenue. Cette relation permet de définir une condition de stabilité. Les présences potentielles de contraintes sur le vecteur d'état et d'incertitudes de modèle ont toutes les deux été considérées. L'efficacité des méthodes proposées est illustrée par deux applications liées à l'automobile : l'estimation de l'état de charge d'une batterie et le contrôle local d'une soupape électromagnétique
Contribution à l'étude expérimentale des écoulements confinés à surfaces libres : application à l'interaction fluide-structure dans un compartiment de JIG artisanal by Cyriaque Donat Randrianantenaina( )

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

The work realized under this co-supervised thesis concerns two study areas of fluid-structure interaction. The first concerned the Mineral Engineering and deals with the interaction between a moving grate in a sluice and the confined flow associated. The second concerns the fundamental Hydrodynamics and deals with the interaction of a cylinder mounted on flexible supports and a free surface flow in presence of plane wall. Our work contributes to the study a confined free surface flow by experimental approach. We coupled techniques of CCD camera visualization, velocity fields measurements by PIV and hydrodynamic forces to qualify the dynamics of structure motion in the flow. Experimental methods and devices are applied to the study the flow around two simplified models of a moving JIG grate and then to study a vibrating cylinder due to flow. Treatments of PIV data acquisitions by multivariable statistical POD enabled us to describe evolution of recirculation zones in the compartment and unsteady velocity field. Experimental study was completed by a numerical simulation of Jig model by using ANSYS14.5 and a numerical wake oscillator model for the case of the cylinder. This work highlighted a simple technique to give motion, in a sluice, a attached net to a cylinder and to study effects of free surface flow confinement on a vibrating cylinder
Contrôle de la propagation des ondes ultrasonores dans des cristaux phononiques piézoélectriques by Sid Ali Mansoura( )

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

The ability to control the propagation of acoustic waves knows in recent years potential applications especially on the manufacture of electrical filter, but also in controlling the mechanical vibration of structures and sound insulation. To achieve this control, the properties of propagations can be changed by external load. The aim of this work is to achieve the control of acoustic waves in phononic crystal using piezoelectric materials. These materials have elastic properties coupled to the electrical properties resulting from their manufacturing process. The vibration of a piezoelectric layer is affected by the electrical boundary conditions imposed on its electrodes. A simple way to consider an electrical boundary condition on piezoelectrical material is to connect an external impedance load (positive capacitance, negative capacitance, inductance) to its electrodes. The resonance frequencies of the piezoelectric layer are then affected differently according the nature of external electric load. The positive capacitance allows to reduce the parallel resonance frequency. A negative capacitance makes it possible to increase the parallel resonance frequency of the piezoelectric layer, giving the ability to use the piezoelectric material away from away from its fundamental resonance frequency. The particular case of an inductive load has a wide possibility to control the propagation of acoustic waves through a piezoelectric pc. We demonstrate that the use of this inductive load opens a hybridization gap in a one-dimensional piezoelectric structure and enable to control the frequency position of this gap. As a result, the hybridization gap causes the opening of a bandwidth within the gap Bragg. The hybridization gap can also cause a high attenuation of acoustic waves in a pass band especially at low frequencies
Stabilité physique de mélanges complexes à caractère cristallin et amorphe : application à l'huile de palme et à la poudre de lait by Anaïs Vuillequez( Book )

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

This report has been realized in the general context of the food-processing problem which concerns the control of product transformations during steps of manufacturing and storage. Following the physical state in which the product appears, these transformations can be of two kinds. In amorphous metastable state, transformations are associated with crystallization, while if the product is in glass state, it evolutions concern the ageing phenomena during which the system relax towards his state of balance. These two aspects are approached in this work. Differential scanning calorimetry measures show that two major ingredients of the studied foodstuff, the Plumpy'nut, present structural modifications in the domain of manufacturing and storage temperature. The first one, palm oil presents low-temperature liquid-crystal transitions whereas the second, milk powder is glassy at room temperature and change to over-melted state at high-temperature. These two compounds are the object of a detailed study of their stability property presented in this report
Discrimination de signaux : contributions aux approches par noyaux et par projection by Florian Yger( Book )

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

Les travaux de cette thèse s'inscrivent dans le cadre de la discrimination de signaux. Notre approche consiste à adapter la représentation des signaux pour en faciliter la classification. Pour cela, nous proposons d'utiliser des méthodes d'apprentissage à noyaux multiples (MKL) ainsi que des notions de géométrie différentielle. Dans notre première contribution, après avoir construit des noyaux à partir de différentes décompositions en ondelettes des signaux, nous montrons comment transformer un problème de représentation discriminante en problème d'apprentissage à noyaux multiples. La famille de noyaux ainsi générée étant de très grande taille, nous proposons une stratégie d'optimisation par contraintes actives pour résoudre efficacement ce problème. Notre deuxième contribution porte sur l'étude de noyaux de matrices de covariance pour la répresentation de signaux. Après avoir tiré partie de la nature riemanienne de l'espace des matrices de covariance dans l'étude de ces noyaux, nous proposons de les utiliser au sein d'un algorithme d'apprentissage à noyaux multiples. Cette approche est ensuite appliquée à des données d'interface cerveau-machine et permet de sélectionner automatiquement les bandes de fréquence pertinentes pour filtrer ces signaux. Enfin, notre dernière contribution considère une résolution adaptative de l'analyse canonique des corrélations (CCA). Après avoir reformulé le problème d'optimisation, nous mettons en oeuvre des techniques d'optimisation sur des variétés différentielles pour aboutir à un algorithme efficace en deux étapes. Cet algorithme est ensuite validé sur une tâche de détection de rupture pour des signaux d'interface cerveau-machine
Modélisation du rayonnement électromagnétique des dispositifs électroniques pour des applications CEM by Priscila Fernandez Lopez( Book )

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

This thesis was performed in IRSEEM and it is under the EPEA project (EMC Platform for Embedded Applications) of Aerospace Valley cluster. Its objective is to develop models of the emissions radiated by electronic devices. These models must be generic (i.e. applicable to any device), easy to obtain and insertable into commercial electromagnetic simulation tools. Firstly, a model capable to predict electric and magnetic fields in the half-space above a device is developed. It is based on a set of electric and magnetic dipole equivalent sources. Two matrix inversions using the least-square inverse method allow their determination. The model is applied to several circuits (passives and actives) with good results. The insertion of the models into commercial simulators is possible thanks to a reduction in the number of sources. This model is then used for two EMC applications. Firstly, the prediction of the coupling between an aggressor device and a transmission line by two different procedures: an analytical one and a numerical one, then the far-field prediction. Finally, another modelling method to recreate the electric and the magnetic fields in the space surrounding the device is proposed and validated on simple cases
Comportements physiques de composites 100 % naturels à base de polysaccharides modifiés et renforcés par des fibres naturelles by Preetha Gopalakrishnan( Book )

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

Des polymères thermoplastiques 100% naturels sont obtenus par extrusion de mélanges à base de farine de blé. La farine utilisée est un sous-produit de la production alimentaire de farine (taux de protéine < 6 - 7 %). Après avoir caractérisé les propriétés physiques des films extrudés, nous avons ajouté de la genipin (réticulant naturel) dans le but d'améliorer les comportements au regard de l'humidité. Nous démontrons que la genipin améliore l'aspect hydrophobe des surfaces des films. Dans la seconde partie du travail, un composite 100 % naturel a été réalisé en ajoutant des fibres de lin. Les interactions d'interface entre la matrice et les fibres sont excellentes et nous montrons qu'il n'est pas nécessaire de traiter chimiquement les fibres pour augmenter leur adhérence. Pour mener à bien ce travail, nous avons utilisé des méthodes d'essais de mécanique, dureté, la diffraction des rayons X (DRX), l'analyse thermique (TGA), l'analyse dynamique mécanique (DMA), la mesure d'angles de contact, l'analyse enthalpique différentielle (DSC), les mesures d'absorption d'eau. Nous pouvons conclure en annonçant qu'une nouvelle famille de composites 100 % naturels (non synthétiques) est proposée
Elements of omnidirectional vision for biometrics at a distance by Yohan Dupuis( Book )

2 editions published in 2012 in English and held by 2 WorldCat member libraries worldwide

La vision omnidirectionnelle est aujourd'hui principalement utilisée pour la navigation et l'estimation de trajectoire en robotique mobile. Dans cette thèse, nous suggérons d'étendre les capacités des capteurs omnidirectionnels. Nous proposons d'utiliser les capteurs omnidirectionnels pour la détection de visage et l'analyse de la démarche. Le développement algorithmique est effectué en respectant la nature intrinsèque des images omnidirectionnelles. Nous avons donc privilégié le traitement des images omnidirectionnelles brutes. Durant ces travaux de recherche, nous avons démontré qu'une image omnidirectionnelle peut être directement utilisée pour effectuer la détection de visage. Ces résultats encourageants vont peut-être amener la communauté du traitement d'image à proposer de nouvelles méthodes conduisant à la détection d'objet sur les images omnidirectionnelles. Dans une seconde partie, nous nous sommes intéressé à la reconnaissance par la démarche. Nous avons proposé une nouvelle signature de la démarche qui permet d'améliorer les performances de reconnaissance dans des conditions complexes
Caractérisation et modélisation comportementale des composants passifs sur une large bande de fréquence en intégrant l'aspect thermique. Application au filtrage CEM by Fahim Hami( Book )

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

Passive components, such as resistors, chokes and capacitors, are widely used in power electronic applications, especially in EMI passive filters. The parasitic elements of these components and the impact of operating conditions (temperature, voltage and current) on their frequency behavior are very significant and should not be neglected; these unwanted effects have a major impact on the global passive circuit performances. This thesis deals with characterization by measurement and modeling of passive components used in power electronics devices, with the aim of estimating and controlling the electromagnetic compatibility of such devices. The thesis was conducted in collaboration with the VeDeCoM and IRSEEM Institutes, including several industry partners of the automotive and avionic sectors. This thesis describes an experimental / modeling approach towards the production of sophisticated models of passive devices, with the inclusion of operational conditions (like temperature effects). The new models are simulated for several values of temperature and load conditions, the obtained results are compared to the experimental measurements in the frequency domain. The developed models are then translated to VHDL-AMS language for an easy implementation in most electrical simulation softwares. Finally, these behavioral models of passive components are subsequently used to model a structure of an EMI filter by integrating the variations of its operating temperature. This model is validated experimentally by comparing, under different constraints, the real behavior of the filter with the simulation results of its developed model
Métrologie des dopants dans les nanostructures ZnO par sonde atomique tomographique by Nooshin Amirifar( Book )

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

In recent years, an increasing number of research studies has been conducted for the development of optoelectronic and electronic devices based on ZnO. The design of these devices requires a total control of synthesis and doping process as they determine the final electrical and optical properties. Today, one major obstacle in achieving such devices is the difficulties of obtaining a p-type ZnO. Achieving this requires proper characterization techniques that can provide direct information about the distribution of dopants. In this thesis, atom probe tomography (APT) has been used to study the incorporation of dopants in ZnO thin films and nanowires. Two types of doping were studied. p-type doping of ZnO nanowires were attempted by two different techniques: one ex-situ process through thermal diffusion into undoped nanowire and the other one through an in-situ incorporation during the wire growth. It was shown that despite the fact that a homogeneous incorporation of dopants was achieved, the doped nanowires showed n-type conductivity. Doping with rare earth elements (RE) was also studied in order to improve the optical properties of ZnO thin films. It has been shown that heat treatments strongly influence the optical properties of the doped thin layers. Analysis by APT has revealed a slight influence of heat treatments on the distribution of dopants. This study shows that the electrical and optical properties of ZnO are strongly dependent on the elaboration and annealing parameters but the most relevant parameter are yet to be discovered
 
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Alternative Names
École doctorale 351

École doctorale SPMII

ED 351

ED Sciences Physiques, Mathématiques et de l'Information pour l'Ingénieur

ED351

SPMII

Languages
French (28)

English (12)