Teses / dissertações sobre o tema "Méthode des éléments finis d'onde"
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Tordjman, Nathalie. "Éléments finis d'ordre élevé avec condensation de masse pour l'équation des ondes". Paris 9, 1995. https://portail.bu.dauphine.fr/fileviewer/index.php?doc=1995PA090002.
Texto completo da fonteMassé, Nadia. "Méthode mixte éléments/volumes finis pour la modélisation numérique de la propagation acoustique par couplage aux éléments de frontière ou aux éléments infinis". Poitiers, 2002. http://www.theses.fr/2002POIT2330.
Texto completo da fonteThe object of this work is the presentation of an original numerical method for the resolution of acoustic propagation problems in infinite domain. The infinite field of study is truncated by a fictitious boundary which thus defines two fields. In the interior field, a mixed Control Volume Finite Element Method (CVFEM) is used in order to solve Helmholtz's equation. The external field is described by a Boundary Element Method or an Infinite Element Method which impose the Sommerfeld's condition. The association of the CVFEM with the Boundary Elements or the Infinite Elements on two-dimensional examples leads to solutions which agree with the analytical and numerical results. The sound refraction into the far-field through a thermal jet in an axisymmetric configuration is then analyzed and its effect on the localization of a fictitious source placed at the conduit exit and on the jet axis is studied by using measurements of acoustic intensity
Truchi, Christine. "Stabilisation par variation du domaine". Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb37610417d.
Texto completo da fonteRada, Kamal. "Contribution à l'étude de systèmes rayonnants par la méthode des éléments finis". Limoges, 1996. http://www.theses.fr/1996LIMO0048.
Texto completo da fonteAubourg, Michel. "Méthode des éléments finis appliquée à des problèmes de propagation d'ondes électromagnétiques guidées". Limoges, 1985. http://www.theses.fr/1985LIMO4004.
Texto completo da fonteChaumont, Frelet Théophile. "Approximation par éléments finis de problèmes d'Helmholtz pour la propagation d'ondes sismiques". Thesis, Rouen, INSA, 2015. http://www.theses.fr/2015ISAM0011/document.
Texto completo da fonteThe main objective of this work is the design of an efficient numerical strategy to solve the Helmholtz equation in highly heterogeneous media. We propose a methodology based on coarse meshes and high order polynomials together with a special quadrature scheme to take into account fine scale heterogeneities. The idea behind this choice is that high order polynomials are known to be robust with respect to the pollution effect and therefore, efficient to solve wave problems in homogeneous media. In this work, we are able to extend so-called "asymptotic error-estimate" derived for problems homogeneous media to the case of heterogeneous media. These results are of particular interest because they show that high order polynomials bring more robustness with respect to the pollution effect even if the solution is not regular, because of the fine scale heterogeneities. We propose special quadrature schemes to take int account fine scale heterogeneities. These schemes can also be seen as an approximation of the medium parameters. If we denote by h the finite-element mesh step and by e the approximation level of the medium parameters, we are able to show a convergence theorem which is explicit in terms of h, e and f, where f is the frequency. The main theoretical results are further validated through numerical experiments. 2D and 3D geophysica benchmarks have been considered. First, these experiments confirm that high-order finite-elements are more efficient to approximate the solution if they are coupled with our multiscale strategy. This is in agreement with our results about the pollution effect. Furthermore, we have carried out benchmarks in terms of computational time and memory requirements for 3D problems. We conclude that our multiscale methodology is able to greatly reduce the computational burden compared to the standard finite-element method
Ridaoui, Khalid. "Contribution à l'étude du couplage électromagnétique guide d'onde - milieu dissipatif : extension aux milieux hétérogènes (application à l'imagerie radiométrique microonde)". Lille 1, 1998. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/1998/50376-1998-389.pdf.
Texto completo da fontePriou, Jean-Pascal. "Contribution à l'étude de la propagation acoustique en milieu non homogène dans les cavités et résonateurs de Helmholtz par la méthode des éléments finis". Poitiers CEAT, 1994. http://www.theses.fr/1994POIT2350.
Texto completo da fonteLeclère, Jean-Michel. "Modélisation parallèle de la propagation d'ondes dans structures par éléments finis adaptatifs". Châtenay-Malabry, Ecole centrale de Paris, 2001. http://www.theses.fr/2001ECAP0737.
Texto completo da fonteNormand, Pierre-Elie. "Application de méthodes d'ordre élevé en éléments finis pour l'aérodynamique". Thesis, Bordeaux 1, 2011. http://www.theses.fr/2011BOR14416/document.
Texto completo da fonteThe areas of research and analysis covered in this thesis focus on methods using high order finite elements applied for solving Navier-Stokes equations and turbulence models. It consists of two main parts:-The implementation of high-order methods in an industrial computer code -The development of a methodology for creating curved meshes on 3D geometries A series of test cases of increasing difficulty were conducted to validate these methods. We present, moreover, a case of a full aircraft where the process used to obtain the full mesh and the Navier-Stokes/turbulence model calculation are fully described and discussed. Motivation, contribution and technical barriers are finally discussed
Redon, Emmanuel. "Etude de la propagation acoustique en espace confiné en présence d'écoulement non isotherme par la méthode des éléments finis". Poitiers, 1996. http://www.theses.fr/1996POIT2253.
Texto completo da fonteGatard, Ludovic. "Méthodes d'équations intégrales de frontière d'ordre élevé pour les équations de Maxwell : couplage de la méthode de discrétisation microlocale et de la méthode multipôle rapide FMM". Bordeaux 1, 2007. http://www.theses.fr/2007BOR13416.
Texto completo da fonteJund, Sébastien. "Méthodes d'éléments finis d'ordre élevé pour la simulation numérique de la propagation d'ondes". Phd thesis, Université Louis Pasteur - Strasbourg I, 2007. http://tel.archives-ouvertes.fr/tel-00188739.
Texto completo da fonteMounkala, Clément. "Effets des singularités géométriques sur les résultats numériques d'une méthode d'éléments finis de frontière dans un problème plan". Compiègne, 1988. http://www.theses.fr/1988COMPD134.
Texto completo da fonteLanglet, Philippe. "Analyse de la propagation des ondes acoustiques dans les matériaux périodiques à l'aide de la méthode des éléments finis". Valenciennes, 1993. https://ged.uphf.fr/nuxeo/site/esupversions/68a1f29e-c829-4081-800c-cb92319703de.
Texto completo da fonteLucanu, Nicolae. "Contribution à l'étude de la diffraction d'une onde électromagnétique plane par des obstacles métalliques en utilisant la méthode itérative basée sur le concept d'onde". Toulouse, INPT, 2001. http://www.theses.fr/2001INPT024H.
Texto completo da fonteLudwig, Bruno. "Etude de quelques problèmes directs et inverses en propagation d'ondes acoustiques transitoires. Méthode d'éléments finis de frontière". Compiègne, 2000. http://www.theses.fr/2000COMP1293.
Texto completo da fonteGrob, Pascal. "Méthodes numériques de couplage pour la vibroacoustique instationnaire : éléments finis spectraux d'ordre élevé et potentiels retardés". Phd thesis, Paris 9, 2006. http://pastel.archives-ouvertes.fr/pastel-00002492.
Texto completo da fonteLéger, Raphaël. "Couplage pour l'aéroacoustique de schémas aux différences finies en maillage structuré avec des schémas de type éléments finis discontinus en maillage non structuré". Thesis, Paris Est, 2011. http://www.theses.fr/2011PEST1030/document.
Texto completo da fonteThis thesis aims at studying coupling techniques between Discontinuous Galerkin (DG) and finite difference (FD) schemes in a non-structured / Cartesian hybrid-mesh context,in the framework of Aeroacoustics computations. The idea behind such an approach is the possibility to locally take advantage of the qualities of each method. In other words, the goal is to be able to deal with complex geometries using a DG scheme on a non-structured mesh in their neighborhood, while solving the rest of the domain using a FD scheme on a cartesian grid, in order to alleviate the needs in computational resources. More precisely, this work aims at designing an hybridization algorithm between these two types of numerical schemes, in the framework of the approximation of the solutions of the Linearized Euler Equations. Then, the numerical behaviour of hybrid solutions is cautiously evaluated. Due to the fact that no theoretical result seems achievable at the present time, this study is mainly based on numerical experiments. What's more, the interest of such an hybridization is illustrated by its application to an acoustic propagation computation in a realistic case
Leger, Raphaël, e Raphaël Leger. "Couplage pour l'aéroacoustique de schémas aux différences finies en maillage structuré avec des schémas de type éléments finis discontinus en maillage non structuré". Phd thesis, Université Paris-Est, 2011. http://pastel.archives-ouvertes.fr/pastel-00679119.
Texto completo da fontePetin, Pascal. "Étude de sensibilité à l'aide des dérivées d'ordre élevé dans la méthode des éléments finis : application à l'électromagnétisme". Grenoble INPG, 1996. http://www.theses.fr/1996INPG0102.
Texto completo da fonteNakhle, Bassam. "Modélisation numérique d'ondes de crues ou de submersion". Pau, 2005. http://www.theses.fr/2005PAUU3006.
Texto completo da fonteIn XIXth century, an observation on the flow nature of floods constitutes the main assumption for a mathematical model given by Barré de Saint-Venant. By supposing that the flow in the case of the floods is two-dimensional, the integration of the Navier-Stokes equations provides a system of equations named Saint-Venant equations. The resolution of these equations is a difficult task regardind their complexity and strong non linearity, but the development of computers and scientific computation facilities makes this problem more accessible. In this work, we present a study of a mathematical analysis and a numerical method of resolution for these equations based on a scheme of finite elements method combined to the method of characteristics. After proving existence and uniquiness results of the solutions, an a priori study of the error estimation is also validated. Some results of simulations on real and academic test cases are presented and compared to those obtained by the reference code "FESWMS". Due to the large size of problems modelled by these equations, a part of this work is devoted for parallel computing with an analysis of algorithms and a MPI implementation followed by the corresponding results of performance
Duruflé, Marc. "Intégration numérique et éléments finis d'ordre élevé appliqués aux équations de Maxwell en régime harmonique". Phd thesis, Paris 9, 2006. http://tel.archives-ouvertes.fr/tel-00068590.
Texto completo da fonteéquations de Maxwell en régime fréquentiel, afin de calculer
précisément la signature radar de cibles diverses. Pour avoir
une grande précision nécessaire pour des expérience de grande taille,
nous utilisons des méthodes d'ordre élevé.
Dans le cas scalaire, les éléments finis spectraux hexaédriques
avec condensation de masse, permettent d'obtenir un produit matrice vecteur
rapide et peux coûteux en stockage. Dans le cas vectoriel, les hexaèdres
de la première famille ne réalisent pas la condensation de masse, mais on peut
écrire un algorithme rapide de produit matrice-vecteur. Des résultats
numériques 3-D montrent la performance de l'algorithme proposé.
Nous traitons également le cas où la géométrie présente
une symétrie de révolution. On est alors ramenés à une succession
de problèmes 2-D indépendants.
Nous proposons une méthode éléments finis d'ordre élevé
couplée à des équations intégrales d'ordre élevé.
Hwang, Syh-Chang. "Etude du chauffage de tissus biologiques par une onde électromagnétique ; application à la modélisation de la thermothérapie". Poitiers, 1995. http://www.theses.fr/1995POIT2334.
Texto completo da fonteMbinky, Estelle Carine. "Adaptation de maillages pour des schémas numériques d'ordre très élevé". Paris 6, 2013. http://www.theses.fr/2013PA066696.
Texto completo da fonteMesh adaptation is an iterative process which consists in changing locally the size and orientation of the mesh according the behavior of the studied physical solution. It generates the best mesh for a given problem and a fix number of degrees of freedom. Mesh adaptation methods have proven to be extremely effective in reducing significantly the mesh size for a given precision and reaching quickly an second-order asymptotic convergence for problems containing singularities when they are coupled to high order numerical methods. In metric-based mesh adaptation, two approaches have been proposed: Multi-scale methods based on a control of the interpolation error in Lp-norm and Goal oriented methods that control the approximation error of a functional through the use of the adjoint state. However, with the emergence of very high order numerical methods such as the discontinuous Galerkin method, it becomes necessary to take into account the order of the numerical scheme in mesh adaptation process. Mesh adaptation is even more crucial for such schemes as they converge to first-order in flow singularities. Therefore, the mesh refinement at the singularities of the solution must be as important as the order of the method is high. This thesis deals with the extension of the theoretical and numerical results getting in the case of mesh adaptation for piecewise linear solutions to high order piecewise polynomial solutions. These solutions are represented using kth-order Lagrangian finite elements (k ≥ 2). This thesis will focus on modeling the local interpolation error of order k ≥ 3 on a continuous mesh. However, for metric-based mesh adaptation methods, the error model must be a quadratic form, which shows an intrinsic metric space. Therefore, to be able to produce such an area, it is necessary to decompose the homogeneous polynomial and to approximate it by a quadratic form taken at power k. This modeling allows us to define a metric field necessary to communicate with the mesh generator. The decomposition method will be an extension of the diagonalization method to high order homogeneous polynomials. Indeed, in 2D and 3D, symmetric tensor decomposition methods such as Sylvester decomposition and its extension to high dimensions will allow us to decompose locally the error function, then, to deduce the quadratic error model. Then, this local error model is used to control the overall error in Lp-norm and the optimal mesh is obtained by minimizing this error. In this thesis, we seek to demonstrate the kth-order convergence of high order mesh adaptation method for analytic functions and numerical simulations using kth-order solvers (k ≥ 3)
Daoud, Thaer. "Modélisation d'un filtre optique pour les télécommunications et éléments de sa réalisation". Limoges, 2000. http://www.theses.fr/2000LIMO0018.
Texto completo da fonteScala, Ilaria. "Caractérisation d’interphase par des méthodes ultrasonores : applicationaux tissus péri-prothétiques". Thesis, Paris Est, 2018. http://www.theses.fr/2018PESC1107/document.
Texto completo da fonteThis thesis focus on the ultrasonic characterization of bone-implant interphase. This region is a transition zone where the osteointegration process (i.e. the healing process of the tissues surrounding the implant) takes place. Thus, this interphase is of crucial importance in the long-term anchorage of the implant, since it depends on the quantity and quality of the surrounding bone tissue. However, other than being a complex medium in constant remodeling, the newly formed bone presents a multiscale and time evolving nature. All these reasons make the characterization of the bone-implant interphase critical and difficult. In this context, ultrasound methods are nowadays widely used in the clinic field because of their ability to give information about the biomechanical properties of bone tissue. On this basis, with the aim of characterizing the mechanical and microstructural properties of the bone-implant interphase by ultrasound methods, it is important to develop and validate mechanical models and signal processing methods. Due to the complexity of the problem, in order to precisely describe the bone tissue surrounding the implant, first an accurate modelling of bone tissue is essential. Thus, the interaction between an ultrasonic wave and bone tissue has been investigated by also taking into account the effects dues to the microstructure. To do this, a generalized continuum modelling has been used. In this context, a transmission/reflection test performed on a poroelastic sample dipped in a fluid enhanced the reliability of the model. The reflected and transmitted pressure fields result to be affected by the microstructure parameters and the results coming from the dispersion analysis are in agreement with those observed in experiments for poroelastic specimens. Then, the problem has been complicated by considering the interphase taking place between the bone and the implant. In this way, we could handle the complexity added by the presence of the newly formed tissue. As already said, the fact that this interphase is a heterogeneous medium, a mixture of both solid and fluid phases whose properties evolve with time is an additional difficulty. Thus, in order to model the interaction of ultrasonic waves with this interphase, a thin layer with elastic and inertial properties has been considered in the model. The effects on the reflection properties of a transition between a homogeneous and a microstructured continuum have been investigated.Therefore, the characterization of the medium also via advanced signal processing techniques is investigated. In particular, the dynamic response due to the ultrasonic excitation of the bone-implant system is analyzed through the multifractal approach. A first analysis based on the wavelet coefficients pointed out a multifractal signature for the signals from both simulations and experiences. Then, a sensitivity study has also shown that the variation of parameters such as central frequency and trabecular bone density does not lead to a change in the response. The originality lies in the fact that it is one of the early efforts to exploit the multifractal approach in the ultrasonic propagation inside a heterogeneous medium
Baronian, Vahan. "Couplage des méthodes modale et éléments finis pour la diffraction des ondes élastiques guidées : application au contrôle non destructif". Phd thesis, Palaiseau, Ecole polytechnique, 2009. http://pastel.paristech.org/5666/01/these_vahanbaronian.pdf.
Texto completo da fonteBergot, Morgane. "Éléments finis d'ordre élevé pour maillages hybrides - Application à la résolution de systèmes hyperboliques linéaires en régimes harmonique et temporel". Phd thesis, Université Paris Dauphine - Paris IX, 2010. http://tel.archives-ouvertes.fr/tel-00556823.
Texto completo da fonteBaronian, Vahan. "Couplage des méthodes modale et éléments finis pour la diffraction des ondes élastiques guidées : Application au Contrôle Non Destructif". Phd thesis, Ecole Polytechnique X, 2009. http://pastel.archives-ouvertes.fr/pastel-00005666.
Texto completo da fonteThiam, Ngueye. "Simulation des ondes lumineuses par une combinaison de la méthode de propagation par faisceaux et d'une discrétisation par éléments finis". Thesis, Université Laval, 2006. http://www.theses.ulaval.ca/2006/23711/23711.pdf.
Texto completo da fonteBavencoffe, Maxime. "Propagation d'ondes de Lamb dans un guide d'ondes à interface périodique". Le Havre, 2009. http://www.theses.fr/2009LEHA0020.
Texto completo da fonteThis work deals with two research fields: the non destructive testing and the phononic crystals. The pursued goal is the study of the relation between the existence of forbidden bands for an infinite phononic crystal and the observed attenuation of the propagating Lamb waves through a limited crystal. Physically, this corresponds to the study of the coupling of vibrating modes faced with a periodic interface. First, a numerical study involving the finite element method thanks to the ATILA® code is performed. An infinite plate made of aluminum with a periodic sinusoïdal corrugation is foremost modeled. For each studied frequency, the complex values of the wavenumber k are obtained. The dispersion curves in the (kʹ, kʺ, f) space are then plotted and show that the values of the imaginary part of the wavenumber (kʺ) are non-null in the frequency ranges of the forbidden bands. These values correspond to evanescent modes. Those modes are characterized by a parametric study (influence of the depth, the number of periods). A finite plate made of aluminum with a periodic sinusoidal corrugation is next considered. The harmonic analysis of this structure allows to link the Lamb waves attenuation and the presence of an evanescent wave existing in an infinite sinusoidal grating. Finally, the experimental study of a finite plate made of aluminum with a periodic triangular corrugation is realized. A measure of the mode conversion is performed and the forming of a coupling between a propagating mode and a backward one under the grating is observed
Jedidi, Rym. "Modélisation des guides d'ondes optiques courbés et caractérisation des pertes par des méthodes d'éléments finis hiérarchiques". Thesis, Université Laval, 2007. http://www.theses.ulaval.ca/2007/24597/24597.pdf.
Texto completo da fonteBériot, Hadrien. "Eléments finis d'ordre élévé pour l'opérateur de Galbrun en régime harmonique". Compiègne, 2008. http://www.theses.fr/2008COMP1791.
Texto completo da fonteInvestments in Computational methods for aeroacoustic have grown recently due to their application in the transportation sector. To account for the flow effects in the propagation zones, the Linearized Euler Equations (LEE) are generally preferred. If robust methods are available in the time domain, practically no methods have been proposed in the frequency domain on unstructured grids. In this manuscript, we propose an original finite element method for the operator of Galbrun, known to be physically equivalent to the LEE. To stabilize the numerical scheme and improve the performance, a mixed high-order approach is employed. A complete dispersion analysis of high-order methods in the presence of flow is performed. Validations are proposed in ducted swirling flows based on Pridmore-Brown's model. Acoustic and hydrodynamic phenomenon are examined as well as the use of non reflecting conditions
Catella, Adrien. "Schémas d'intégration en temps efficaces pour la résolution numérique des équations de Maxwell instationnaires par des méthodes Galerkin discontinues d'ordre élevé en maillages non-structurés". Nice, 2008. http://www.theses.fr/2008NICE4106.
Texto completo da fonteThis general objective of this study is the development and assesment of efficient time integration scheme for Discontinuous Galerkin time domain (DGTD) method on unstructured tetraedral meshes for numerical resolution of Maxwell equations. In first part of this thesis, we remind Maxwell's equations and summarize main numerical methods used to solve this system. In the second part, we present the Discontinuous Galerkin method based on centred approximations for generic order. In this chapter, we focuse to time explicit scheme. We detailed, in third chapter, the main part of this work, in other words time implicit scheme, especially the Crank-Nicolson scheme, which is most studied in scientific litterature and in a second time a scheme of order 4 obtained by the defect correction technique. We realized a comparative study of both solvers (iterative and direct) to solve the linear system in chapter 4. For a memory space consideration , we apply the implicit scheme on a subdomain only. To do this, we use a hybrid explicit/implicit scheme. On chapter 6, we present the results 3D obtained with this method. Problems considered has several millions unknowns
Duquenne, Laurent. "Développement d'une méthode d'estimation de la génération transitoire d'ondes de Lamb : Application à la modélisation d'un système de contrôle santé intégré". Valenciennes, 2003. http://ged.univ-valenciennes.fr/nuxeo/site/esupversions/2807daf5-ac69-4a5c-a2ae-2ab8d5e7fb56.
Texto completo da fonteFor several year, research has been undertaken to integrate a nondestructive evaluation system in the structure with the objective to facilitate regular monitoring. This " health monitoring system " would allow the selection of the components requiring repairs. The technique considered is the use of the Lamb waves generated by integrated piezoelectric transducers which are able to emit or to receipt this waves. Nevertheless, the control of the generated waves by these transducers is still a problem. The aim of this work is then to develop a method allowing to estimate the transient generation of Lamb wave. The advantage of the hybrid method finite elements/Normal mode expansion is the direct computation of the contribution of each mode. The assumptions have been checked and the results have been confronted successfully with experimental results
Després, Bruno. "Méthodes de décomposition de domaine pour la propagation d'ondes en régime harmonique. Le théorème de Borg pour l'équation de Hill vectorielle". Paris 9, 1991. https://portail.bu.dauphine.fr/fileviewer/index.php?doc=1991PA090032.
Texto completo da fonteKe, Weina. "Simulation 3D de la génération et de la réception d'ondes guidées : application à la détection de défauts dans des structures composites". Thesis, Bordeaux 1, 2009. http://www.theses.fr/2009BOR13805/document.
Texto completo da fonteThe Non Destructive Testing (NDT) of materials is rapidly expanding in the fields of aeronautics aerospace, transportation, and so on. Guided ultrasonic waves are a powerful means for the implementation o the NDT because they can spread over large distances while interviewing through structures. The use of air coupled transducer allows both non-contact NDT and non-disassembly of tested parts. This thesis is mainly about three-dimensional finite element modelling, and an ultrasonic NDT system based on guided waves. The model takes into account the finite size transducers, the angle of beam diffraction in all directions, anisotropy viscoelasticity and heterogeneity of materials. The numerical predictions are systematically compared with experimental measurements. Three specimens have been studied with success: an aluminium plate with a hole glass-fibre plate with an impact damage, a high pressure tank provided by ASTRIUM with a disbonding defec between the liner titanium layer and wound carbon - fibre
Granat, Cristel. "Formulation variationelle par équations intégrales pour des problèmes de diffraction d'ondes acoustiques et élastiques dans un demi-plan". Compiègne, 2000. http://www.theses.fr/2000COMP1298.
Texto completo da fonteMarmorat, Simon. "Modèles asymptotiques et simulation numérique pour la diffraction d'ondes par des petites hétérogénéités". Electronic Thesis or Diss., Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLY001.
Texto completo da fonteThis work is dedicated to the study of the diffraction of acoustic waves by a set of small inclusions, as well as to the development of numerical methods for the simulation of such phenomenons. The main novelty of this work is that we deal with time-domain waves.The first part of this manuscript deals with the asymptotic analysis of the diffraction problem, which is carried out by matched asymptotics, the small parameter being the characteristic size of the defects ε. This furnishes an asymptotic expansion of the acoustic field as a perturbation of the defect-free problem. We prove a consistency result between the total field and its ε-asymptotic expansion.In the second part, using the results of the asymptotic analysis, we introduce two approximate models for the diffraction problem. These models are well-posed and their solution are precise approximations of the total acoustic field. One of the main features of these approximate models is that they both lie on a wave equation in the surrounding medium (without defects), coupled to auxiliary source terms which account for the presence of the inclusions. It is then possible to discretize these approximate models using a finite element method, leading to a numerical method which performs as fast as in the defect-free case, since the underlying wave operator is independent of the defects. We present several numerical results which validate both approximate models as well as some insights about numerical error analysis
Moreau, Ludovic. "Simulation de la diffraction d'ondes guidées ultrasonores par des défauts dans des plaques". Bordeaux 1, 2007. http://www.theses.fr/2007BOR13543.
Texto completo da fonteOster, Alain. "Electromagnètisme dans les composites : homogènéisation et propagation d'ondes". Paris 6, 1994. http://www.theses.fr/1994PA066663.
Texto completo da fonteDuval, Jean-Baptiste. "Détection numérique de petites imperfections de conductivité en 2D et 3D par une méthode dynamique basée sur l'équation des ondes et le contrôle géométrique". Phd thesis, Université de Picardie Jules Verne, 2009. http://tel.archives-ouvertes.fr/tel-00429530.
Texto completo da fonteMadec, Ronan. "Méthode des éléments spectraux pour la propagation d'ondes sismiques en milieu géologique fluide-solide avec pas de temps locaux et couches absorbantes parfaitement adaptées C-PML". Phd thesis, Université de Pau et des Pays de l'Adour, 2009. http://tel.archives-ouvertes.fr/tel-00511418.
Texto completo da fonteBen, Souf Mohamed Amine. "Approche stochastique à base de modes d'ondes : théorie et applications en moyennes et hautes fréquences". Thesis, Ecully, Ecole centrale de Lyon, 2012. http://www.theses.fr/2012ECDL0035/document.
Texto completo da fonteThe prediction of dynamic behavior of structures is an important task in the design step of any mechanical product. There are many factors affecting the choice of the used methods. For a dynamic system, the frequency band under study is one of the important parameters since for each frequency range exists its appropriate approach which can be quickly inapplicable in other domains. For example, the high frequency methods are very limited in the lower part of the spectrum. Similarly, the so-called low-frequency methods become numerically inefficient if it goes up in frequency range. The mid-frequencies then represent the high-frequencies for global and low frequencies for local methods. Knowing that uncertainties play an important role on the vibro-acoustics behavior in mid-frequencies, the presented work is a contribution to the research approach, with inexpensive computing time, allowing the extension of a local method, called ’the wave finite element method’, in this frequency band. These contributions consist in taking into account uncertainties in the studied system to evaluate the dispersion of all parameters (spectral, diffusion, dynamics, etc.) and their effects on the global response (kinematic and energetic) of the structure. The presented work can be divided into two main parts. The first one involves the development of an explicit and direct formulation describing the dispersion of different parameters; this part is based on the first-order perturbation method. The second part is a generalization of the first one; indeed, using the chaos polynomial projection of all random variables allows a more general assessment of the effects of uncertainties on the dynamics of periodic structure in mid-frequency range
Vacus, Olivier. "Modélisation de la propagation d'ondes en milieu ferromagnétique". Châtenay-Malabry, Ecole centrale de Paris, 1997. http://www.theses.fr/1997ECAP0607.
Texto completo da fonteImbert, David. "Propagation d'ondes acoustiques dans une suspension de grains mobiles immergés : couplage de modèles discret et continu par la méthode des domaines fictifs". Phd thesis, Université Rennes 1, 2013. http://tel.archives-ouvertes.fr/tel-00955389.
Texto completo da fonteMartz, Yannick. "Modélisation et commande de systèmes d'entraînement de bandes flexibles : nouvelles approches à l'aide des éléments finis". Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAD016.
Texto completo da fonteRoll-to-Roll systems are used in the manufacturing of a wide variety of everyday products as well as in metallurgy and for the manufacturing of new technologies. The improvement of Roll-to-Roll systems is a difficult problem because they are large, non-linear, with varying and uncertain parameters. They have a coupling between the different parts (mechanical and control) with the help of the web connecting the elements. It is therefore necessary to improve the process line through a multidisciplinary approach. The objectives are to master the key parameters of these systems in order to guarantee the manufacturing rates and the more important accuracies requested. It is also necessary to reduce or remove the most recurring defects such as web wrinkles. Until now, only 1D models were used. They are essential for control synthesis and frequency studies but they do not allow to study complex phenomena such as web wrinkles. A new approach for studying these systems is developed. First, improvements of control structures are proposed. Secondly, a 3D finite element model using a flexible multibody dynamics algorithm is developed, used in this work to study web wrinkles and compared to the classical prediction theory of these defects. Finally, a complete simulator is developed including the mechanical 3D model by finite element coupled to the control part (co-simulation)
Grigoroscuta-Strugaru, Magdalena. "Contribution à la résolution numérique des problèmes de Helmholtz". Phd thesis, Université de Pau et des Pays de l'Adour, 2009. http://tel.archives-ouvertes.fr/tel-00473486.
Texto completo da fonteOuedraogo, Boureima. "Modélisation du rayonnement acoustique dans les guides traités par des matériaux absorbants à réaction localisée ou non localisée en présence d'écoulement par la méthode des éléments finis". Phd thesis, Université de Bourgogne, 2011. http://tel.archives-ouvertes.fr/tel-00674031.
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