Dissertations / Theses on the topic 'Crâne – Simulation par ordinateur'
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Baumgartner, Daniel. "Mécanismes de lésion et limites de tolérance au choc de la tête humaine : Simulations numériques et expérimentales de traumatismes crâniens." Université Louis Pasteur (Strasbourg) (1971-2008), 2001. http://www.theses.fr/2001STR13229.
This study proposes new head tissues mechanical tolerance limits belonging to specific injury mechanisms consecutively to an impact. The employed methodology consists in both a finite element modelling (FEM) and a physical modelling of 66 real world accidents of helmeted motorcyclists and American footballers, pedestrians and ballistic projectiles impacts. Initially, an extension of the field of validity of the ULP FEM of the human head to strong dampened long duration impacts with high rotational component, as well as a parametric and a sensitivity analysis are proposed. Moreover, the ULP FEM of the human head is controlled with the real kinematics sustained by each accident victim. A correlation study between the calculated head mechanical field parameters on the one hand, and the observed injuries on the other hand, leads to the identification of injury mechanical criteria. A global strain energy of the subarachnoidal space of 5. 4 J leads to subdural or subarachnoidal haematoma. A brain Von Mises stress of 18 kPa generates moderate neurological lesions which can become severe from 38 kPa. A global strain energy of the skull of 2. 2 J leads to bone rupture. Two severity scale for global injury statement of a victim are equally developed. The experimental injury mechanical criteria are obtained thanks to the physical prototype Bimass 150 of the human head used in the framework of an experimental reconstruction of 13 helmeted motorcyclists accidents. A brain linear acceleration of 273 g causes subdural or subarachnoidal haematoma. A brain angular acceleration of 25970 rad/sø, as well as a relative acceleration between the brain and the skull of 78 g, generates neurological lesions
Munsch, Marie. "Élaboration d’une méthodologie de reconstruction numérique d’accidents réels piéton." Strasbourg, 2011. https://publication-theses.unistra.fr/public/theses_doctorat/2011/MUNSCH_Marie_2011.pdf.
Pedestrians are considered the most vulnerable road users and alone account for 13% of killed in road accidents in France. For several years, to improve pedestrian safety, the first step was to understand the relationship between vehicle design and mechanisms of pedestrian injuries. Mathematical multibody models of pedestrians and vehicles have been developed to simulate the kinematics of the victim during impact with the vehicle. These are the modeling efforts that should lead to the definition of the initial conditions of the head at impact for the simulation of head injury using a finite element modeling. In this context, the objective is to develop a methodology for the reconstruction of real pedestrian accident to determine its kinematics and to simulate the head injury. This last step will ultimately extract head injury criteria more accurate than the criteria currently used. It is thus necessary to define mathematical models of vehicle and pedestrian. An evaluation of different models of multibody neck models and head boundary conditions was performed using a multi-modal analysis. Then the thesis will be on developing an automated method of reconstruction of the pedestrian kinematics with multibody modeling. An application of the developed tool is performed on a database of 8 real accidents of pedestrian vs. Vehicle
Angla, Célestine. "Fast transcranial acoustic simulations for personalized dosimetry in ultrasound brain therapy." Electronic Thesis or Diss., université Paris-Saclay, 2023. http://www.theses.fr/2023UPAST207.
Ultrasound brain therapy is a promising method, as it is non-invasive when ultrasonic waves are sent through the skull. However, the skull bone complex structure strongly attenuates and aberrates the ultrasound beam, altering the dimensions, position and intensity of the focal spot. These focal parameters must be perfectly controlled to ensure both treatment efficacy and safety. Due to the high inter/intra-individual variability of skull geometry and acoustic properties, personalized simulations are required to predict focal characteristics depending on the patient skull and the ultrasonic probe position. Most simulation methods currently in use, such as k-Wave, are very time- and memory-intensive, limiting them to pre-intervention planning tools. The aim of this thesis was to develop a fast and realistic semi-analytical method for ultrasound field computation through the skull. As a first step, we developed a smooth and homogeneous model of the skull, realistic and suited to fast field computation algorithms. To this end, we modeled the skull inner and outer surfaces using a method called "Multi-level Bspline Approximation", and we developed a skull acoustic property homogenization method, which was numerically validated. This smooth and homogeneous skull model was then used as input to the field computation algorithm developed. This algorithm, named SplineBeam, is based on an ultrasonic path computation method that minimizes the time-of-flight function, which is fast and accurate, and which, combined with the pencil method, enables a regular sampling of the ultrasound probe. SplineBeam was validated numerically, by comparison with the pencil method, embedded in the CIVA HealthCare simulation platform, developed at the CEA, and with other numerical solvers (including k-Wave) on a series of configurations, and experimentally, by comparison with hydrophone measured pressure fields through an ex vivo skull sample. SplineBeam simulated fields were found to be closer to the experimentally measured ones than those simulated with k-Wave. This validates both the skull model and the field computation method. Furthermore, SplineBeam can restrict its computation to the focal spot, which allows it to drastically reduce the number of computation points, making it faster than k-Wave by two orders of magnitude, for a large probe
Djian, Francis. "Modélisation thermique des thermostats pour oscillateurs à quartz et applications." Besançon, 1991. http://www.theses.fr/1991BESA2021.
Béraud, Nicolas. "Fabrication assistée par ordinateur pour le procédé EBM." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAI052/document.
The Electron Beam Melting (EBM) process allows to build metallic parts from powder. Thanks to the geometric and mechanical quality of the parts produced, the EBM process can be used to manufacture functional parts and not only prototypes. This process, with other additive metallic processes, make it possible to consider a transition from 3D printing to metallic additive manufacturing.The use of additive manufacturing in an industrial environment requires compliance with quality, cost and time criteria for the parts produced. The production of manufactured parts involves a series of numerical stages which is called the numerical chain. The numerical chain has a significant impact on the three criteria mentioned above. Thus, this thesis provides an answer to the following question:How Computer Aided Manufacturing can improve the quality, cost and time of the EBM manufacturing process?This problem is addressed through the following underlying question:What are the required characteristics for a Computer Aided Manufacturing system adapted to the EBM process?In order to answer this question, the current numerical chain is analyzed. Three main limitations are found:- the use of STL files format- the process cannot be optimized at different scales- the process cannot be simulatedTo solve these issues, a CAM environment is proposed. It allows the centralization of all numerical operations in a single environment. All supported formats can be used within this environment, such as native CAD file formats or STEP format. Software developments are done to prove the feasibility of such an environment.The CAM environment implementation reveals the crucial role of simulation in this system. It is therefore necessary to answer this second question:How to obtain an EBM process simulation allowing the development of parameters, virtually?Although EBM simulation is a recurrent subject in scientific literature, existing studies are based on the finite elements method but the calculation time needed is too important to be used in an CAM environment. Thus, an alternative type of simulation is created in this thesis: a simulation based on abacus. It is composed of a finite elements model, that allows heat maps generation for standards cases of heating and cooling. These heat maps are then transformed in abacus. The simulation algorithm based on abacus search the nearest abacus from the simulated situation in order to estimate the temperatures at the next time step.This simulation method was used to reduce the calculation time while keeping a sufficient precision to optimize process parameters.With the simulation based on abacus, a tool for the optimization of melting strategies is developed. This tool allows quality improvement for the produced parts through the calculation of melting strategies according to thermic criteria.To summarize, the main contributions of this work are:- the definition of requirements specifications of a powerful numerical chain for the EBM process- the development of a CAM environment adapted to the EBM process- the proposal of a fast simulation for the EBM process, based on abacus- the development of a tool for the optimization of melting strategies
Louin, Jean-Charles. "Effets d'hétérogénéités de teneur en carbone sur les cinétiques de transformations de phase et sur la genèse des contraintes internes lors du refroidissement d'aciers." Vandoeuvre-les-Nancy, INPL, 2003. http://www.theses.fr/2003INPL077N.
Heat treatment is a process that needs the control of both final microstructures and residual stresses and deformations. Numerical simulation is a useful tool for a better optimization of this process. The aim of our work was to contribute to the development of a numerical tool for the prediction of microstructures, stresses and strains during cooling of pieces that may contain chemical heterogeneities, particularly carbon content heterogeneities. Firstly, an existing model for the prediction of transformation kinetics in steels has been further developped in order to take into account the effects of the carbon content enrichment of austenite due to a partial ferritic transformation on the subsequent transformations. Coupled thermal, metallurgical, mechanical calculations have then been performed to study the effects of carbon content gradients on the microstructural evolutions and on the residual stresses development during cooling. Particularly, the possible effects of solidification macro and mesosegregations have been quantified in massive cylinders with sizes close to the size of an ingot. Secondly, experimental validations have been performed for homogeneous cylindrical specimen (40CrMnMo8 steel) and for a chemically heterogeneous specimen specifically designed for our study. The complete set of input data necessary for the simulations has been established from experimental characterizations of the steel. The role of chemical heterogeneity has been analysed through the experimental and calculated results. Finally, a good correlation has been obtained between measurements and calculation of the deformation during cooling of a 3D "croissant" shaped specimen
Sech, Nicolas Le. "Photocathodes à base de nanotubes de carbone sur substrats semi-conducteurs de type III-V. Application aux amplificateurs hyperfréquence." Palaiseau, Ecole polytechnique, 2010. http://pastel.archives-ouvertes.fr/docs/00/50/14/43/PDF/These_N_Le_Sech.pdf.
Fauchet, Gauthier. "Modélisation en deux points de la turbulence isotrope compressible et validation à l'aide de simulations numériques." Lyon 1, 1998. http://www.theses.fr/1998LYO10027.
Menezla, Rabea. "Réalisation d'un logiciel de résolution de l'équation de poisson à trois dimensions : Simulation numérique tridimensionnelle du claquage des composants à jonctions P-N." Ecully, Ecole centrale de Lyon, 1990. http://www.theses.fr/1990ECDL0027.
Joly, Cécile. "Simulations numériques d'un jet rond turbulent et de son interaction avec un tourbillon de sillage." Université de Marne-la-Vallée, 2002. http://www.theses.fr/2002MARN0147.
The general context of this study concerns the impact of contrails, these famous white plumes frequently observed in the aircraft wake, on the atmosphere. From an aerodynamic point of view, the formation of the contrails is characterised by the interaction between a turbulent jet and a wing-tip vortex. The aim of this thesis is to contribute to a better understanding of the thermal and dynamic phenomena involved in this flow. This work is based on the numerical resolution of the three-dimensional, unsteady and compressible Navier-Stokes and energy conservation equations. Two approaches are considered: the direct numerical simulation and the large eddy simulation. A temporal simulation of the transition to turbulence of a non-isothermal jet is performed without accounting for the vortex flow field. A the end of this simulation, a vortex model is superimposed on the jet flow field. The first part of this thesis describes the two approaches, the different subgrid models chosen for the large eddy simulations, and the numerical techniques employed. The second part is devoted to the jet flow simulation, and here the objective is to determine the subgrid model appropriated to this flow configuration. The third part is dedicated to the simulation of interaction between the jet and the vortex. Results are compared to experimental data. The simulations have demonstrated the development of large scale structures all around the vortex core. The temperature field concentrates in the large scale structures
Quatravaux, Thibault. "Évolution de la modélisation du procédé VAR : contribution à la description de la dispersion inclusionnaire dans le puits liquide et à la prévention de défauts de solidification." Vandoeuvre-les-Nancy, INPL, 2004. http://www.theses.fr/2004INPL037N.
This thesis deals with the modelling of Vacuum Arc Remelting process (VAR) using the numerical software SOLAR. The first aim of the study is a better description of several physical phenomena which occur during melting, in order to extend the application of the software to simulate the remelting of steel. The evolution in the modelling of transport phenomena in the secondary ingot is based on three major improvements: - lateral thermal transfer modelling, in order to take into account the formation of a gap between the ingot and the mould walls, a possible injection of a neutral gas, and the heating of water in the coolant circuit, according to its flow, - a better turbulence model, since the k-E model implemented previously in the numerical code was not accurate enough to correctly descri~ the flow of the liquid metal in the pool, - a new method to simulate the ingot growth, based on a cyclic operation of splitting and growth/migration of control volumes, which reproduces the continuous growth of the secondary ingot and allows for the refinement of the mesh close to the free surface. Finally, the improved model has been validated by comparison with experimental results provided from four remeltings carried out on full-scale furnaces. The second objective is the characterization of the quality of the manufactured products in terms of inclusion cleanliness and risk of freckles segregated channel generation. Ln order to describe the behaviour of inclusions in the liquid pool, a trajectory model, adapted to account for turbulent flows, was validated and then implemented in the code. Various particle behaviours were distinguished. A study on the risk of freckles generation led to the establishment of a criterion particularly weIl adapted to the process. A generalization of this criterion, suggested in this work, would allow the prediction of the probable orientation of such segregated channels
Ribot, Bénédicte. "Modélisation numérique d'un système de ventilation d'un tunnel routier par une trappe de désenfumage dans le cas d'un incendie." Lyon 1, 1999. http://www.theses.fr/1999LYO10195.
Yu, Qizhi. "Modèles de rivières animées pour l'exploration intéractive de paysages." Grenoble INPG, 2008. http://www.theses.fr/2008INPG0126.
Rivers are ubiquitous in nature, and thus are an important component of the visual simulation of nature scenes. In nature, rivers are dynamic, therefore animation of rivers is necessary in these visual simulation applications. However, animation of rivers is a challenging problem. It incorporates multi-scale surface details and flow motion, and many phenomena involved have complex underlying physical causes. River animation is particular difficult in emerging interactive applications like Google Earth or games, which allow users to explore a very large scene and observe rivers at a very small scale or a very large scale at any moment. Controlling the design of water simulations is another hard problem. The goal of this dissertation is to achieve real-time, scalable, and controllable river animation with a detailed and space-time continuous appearance. To achieve this goal, we break down the river animation problem into macro-, meso-, and micro-scale subproblems from coarse to fine. We propose appropriate models for each scale that capture relevant surface details and fluid motion. In the macro-scale, we propose a procedural method that can compute velocities of rivers with curved banks, branchings and islands on the fly. In themeso-scale, we propose an improved featured-based simulationmethod to generate the crests of the quasi-stationary waves that obstaclesmake. We also propose a method for constructing an adaptive and feature-aligned water surface according to the given wave crests. In the micro-scale, we propose the use of wave sprites, a sprite-based texture model, to represent advected details with stationary spectrum properties on flow surfaces. Armed with wave sprites and a dynamic adaptive sampling scheme, we can texture the surface of a very large or even unbounded river with scene-independent performance. In addition, we propose a Lagrangian texture advection method that has other applications beyond river animation. We demonstrate that combining our models in three scales helps us incorporate visually convincing animated rivers into a very large terrain in real-time interactive applications
Diener, Julien. "Acquisition et génération du mouvement de plantes." Grenoble INPG, 2009. http://www.theses.fr/2009INPG0080.
The primary goal of my Ph. D. Has been to develop innovative animation techniques for virtual plants. Two main approaches have been explored: the reproduction real motion and real-time simulation. First, I have mixed vision algorithms and user interface in order to extract reliable motion data from videos. An innovative method has then been designed to estimate a valid hierarchical structure of branches using statistical study which is used to retarget the video movement on a wide range of virtual plants. Second, I have developed new animation method that computes the response of plants to interactively controllable wind. The main contribution has been to show that simple approximations of the wind load model leads to a drastic reduction of the run-time computations. The simulation algorithm takes full advantage of the parallel processing capabilities of computer graphics cards allowing the animation of thousand trees in real-time
Benchamma, Mérièm. "Réalisation d'un simulateur d'étude et de faisabilité pour la radiothérapie externe dynamique." Aix-Marseille 3, 1995. http://www.theses.fr/1995AIX30013.
Chen, Haifeng. "Système de simulation de spectres de masse assisté par ordinateur." Paris 7, 2003. http://www.theses.fr/2003PA077143.
Farissier, Pierre. "Etude d'un modèle cartographique adapté à la simulation des écoulements en rivières." Lyon 1, 1993. http://www.theses.fr/1993LYO10278.
Bonelli, Stéphane. "Contribution à la résolution de problèmes élastoplastiques de mécanique des sols et d'écoulements non saturés par la méthode des éléments finis." Aix-Marseille 2, 1993. http://www.theses.fr/1993AIX22038.
Chaillat, Stéphanie. "Méthode multipôle rapide pour les équations intégrales de frontière en élastodynamique 3-D : application à la propagation d’ondes sismiques." Paris Est, 2008. http://pastel.paristech.org/5233/01/these_chaillat.pdf.
Simulating wave propagation in 3D configurations is becoming a very active area of research. The main advantage of the BEM is that only the domain boundaries are discretized. As a result, this method is well suited to dealing with unbounded domains. However, the standard BEM leads to fully-populated matrices, which results in high computational costs in CPU time and memory requirements. The Fast Multipole Method (FMM) has dramatically improved the capabilities of BEMs for many areas of application. In this thesis, the FMM is extended to 3D frequencydomain elastodynamics in homogeneous and piecewise-homogeneous media (using in the latter case a FMM-based BE-BE coupling). Improvements of the present FM-BEM are also presented: preconditioning, reduction of the number of moments, and formulation of a multipole expansion for the half space fundamental solutions. Seismological applications are given for canonical problems and the Grenoble valley case
Reimeringer, Michael. "Une méthodologie et des outils pour concevoir en tenant compte de la simulation." Reims, 2009. http://www.theses.fr/2009REIMS001.
Simulation becomes incontrovertible due to the many advancement made in model, software and material. The use of simulation tools supply many advantages: study of alternative solutions, optimization of product, decrease or disparition of physical prototypes, assessment of manufacturing process, and reduction of cost and delay. Nowadays design is often done without considering subsequent step like simulation. However this step is indispensable
Charentenay, Julien de. "Simulation numérique d'écoulements réactifs instationnaires à faibles nombres de Mach." Châtenay-Malabry, Ecole centrale de Paris, 2002. http://www.theses.fr/2002ECAP0724.
Dubois, Jean-Luc. "L'abstraction fonctionnelle des parties contrôles des circuits pour l'accélération de simulateurs générés : une contribution au développement d'outils de C.A.O. de l'architecture matérielle." Lille 1, 1991. http://www.theses.fr/1991LIL10037.
Boyère, Emmanuel. "Contribution à la modélisation numérique thermomécanique tridimensionnelle du forgeage." Paris, ENMP, 1999. http://www.theses.fr/1999ENMP0915.
Jamme, Stéphane. "Étude de l'interaction entre une turbulence homogène isotrope et une onde de choc." Toulouse, INPT, 1998. http://www.theses.fr/1998INPT046H.
Albaki, Rachida. "Contribution à l'étude des propriétés dynamiques des métaux liquides simples par simulation numérique et modèles analytiques." Metz, 2002. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/2002/Albaki.Rachida.SMZ0205.pdf.
Gassenbauer, Václav. "Illumination coherence for ligh transport simulation." Rennes 1, 2011. http://www.theses.fr/2011REN1S098.
La simulation de la propagation de la lumière dans une scène est une tâche essentielle en synthèse d'images réalistes. Cependant, une simulation correcte de la lumière ainsi que ses différents rebonds dans la scène reste couteuse en temps de calcul. Premièrement, nous proposons l'algorithme de cache de luminance spatial et directionnel SDRC. L'algorithme SDRC tire parti du fait que les variations d'éclairage sont douces sur les surfaces brillantes. L'éclairage en un point de la scène est alors calculé en interpolant l'éclairage indirect connu pour un ensemble d'échantillons de luminance spatialement proches et de directions similaires. Dans la partie suivante, nous présentons un algorithme efficace et précis d'analyse locale en composantes principales LPCA pour réduire la dimension et compresser un grandensemble de données. Pour améliorer l'efficacité de notre nouvel algoritme celui-ci propage les informations issues d'une itération à une itération suivante. En choisissant une meilleure graine initiale pour les centroïdes des clusters dans LPCA, la précision de la méthode est améliorée et produit une meilleure classification des données. Enfin, nous décrivons des travaux en cours de réalisation concernant une méthode de ré-éclairage interactif d'une séquence animée en prenant en compte l'éclairage indirect. Le problème de ré-éclairage est représenté sous la forme d'une grande matrice 3D représentant la propagation de la lumière dans la scène pour plusieurs images de la séquence. Un algorithme adaptatif pré-calcule la propagation de la lumière en exploitant les cohérences potentielles
Zhang, Xiao Hui. "Simulation avancée des circuits micro-ondes." Paris 12, 1989. http://www.theses.fr/1989PA120040.
Vettorel, Thomas. "Polymer crystallization studies by computer simulation." Université Louis Pasteur (Strasbourg) (1971-2008), 2005. https://publication-theses.unistra.fr/public/theses_doctorat/2005/VETTOREL_Thomas_2005.pdf.
Semi-crystalline polymers are of great interest for industrial purposes, and the complex structures they involve as well as the mechanisms leading to the formation of crystals make their study very challenging. We investigated polymer crystallization by computer simulation via different methods: An atomisticly detailed model was used to reproduce the crystalline structure of short alkanes at low temperature, and continuous heating simulations gave rise to a transient phase that is well characterized in experiments. The same realistic model was used to simulate continuous cooling of the melt, but could not yield crystalline structures in a limited simulation time. In order to reproduce efficiently the characteristic features of semi-crystalline polymers, we used another simulation model which addresses larger length and time scales: This coarse-grained model allowed us to study the crystallization phenomenon in detail with several order parameters to characterize the crystal and its time evolution. The detailed study of the structure factors of the high-temperature melt has also been investigated so as to determine the influence of the liquid phase structure on crystal formation. These different studies yield a better understanding of the influence on crystallization of the various parameters entering the definitions of the simulation models
Brocail, Julien. "Analyse expérimentale et numérique du contact à l'interface outil-copeau lors de l'usinage à grande vitesse des métaux." Valenciennes, 2009. http://ged.univ-valenciennes.fr/nuxeo/site/esupversions/6c282378-ea86-4bf0-8c06-48498e37e0da.
The study relates to the characterization of the tool-chip interface during the high-speed machining of metals. The existing numerical approaches do not generate good correlations of the process variables, such as the cutting forces and the shape of the chip. Recent studies show that the determination of an interfacial law according to the contact parameters (contact pressure, sliding velocity and interfacial temperature) is necessary to describe more precisely the process parameters. Experiments were carried out on the upsetting sliding test that reproduces the mechanics and thermals contact conditions of the HSM process at the tool tip. This specific device has been adapted and the antagonists have been modified for this study. A friction law according to the contact pressure, the sliding velocity, and the interfacial temperature was defined for the tribological system AISI 1045 steel / uncoated carbide. This law implemented in a numerical model of orthogonal cutting (developed in Abaqus) offers interesting improvements
Mohamed, Kamel. "Simulation numérique en volume finis, de problèmes d'écoulements multidimensionnels raides, par un schéma de flux à deux pas." Paris 13, 2005. http://www.theses.fr/2005PA132020.
This thesis is devoted to the numerical simulation of stiff fluid flows, governed by sys¬tems of conservation laws with source terms (non homogeneous systems). Both one dimensional and two-dimensional configurations are considered. The numerical method used is an extension of the two steps flux scheme (SRNH), which depends on a local adjustable parameter aj+i and which has been proposed by professor F. Benkhaldoun in the one dimensional framework. In a first part of the work, aiming to extend the scheme to the two-dimensional case, we introduce an alternative scheme (SRNHR), which is obtained from SRNH by replacing the numerical velocity, by the local physical Rusanov velocity. Thereafter, the stability analysis of the scheme, shows that the new scheme can be of order 1 or 2 according to the value of the parameter 0j+1. A strategy of variation of this parameter, based on limiters theory was then adopted. The scheme can thus be turned to order 1 in the regions where the flow has a strong variation, and to order 2 in the regions where the flow is regular. After this step, we established the conditions so that this scheme respects the exact C-property introduced by Bermudez and Vazquez. A study of boundary conditions, adapted to this kind of two steps schemes, has also been carried out using the Riemann invariants. In the second part of the thesis, we applied this new scheme to homogeneous and non¬homogeneous monophasic systems. For example, we performed the numerical simulation of shallow water phenomena with bottom topography in both one and two dimensions. We also carried out a numerical convergence study by plotting the error curves. Finally, we used the scheme for the numerical simulation of two phase flow models (Ransom ID and 2D)
Dridi, Samia. "Essais de caractérisation des structures tissées." Lyon, INSA, 2010. http://theses.insa-lyon.fr/publication/2010ISAL0041/these.pdf.
In this work, we interested to the study and the modelling of mechanical behaviour of weave structure. We begin by presenting the properties of tested materials thanks to tests of characterization. An experimental data base is established to analyze the mechanical behaviour of fabric under some solicitations, in particular the shear, using the technique of digital image correlation. Then, by adopting a hyperelastic approach, a simplified model is developed allowing to study numerically the influence of the report of tensile and shearing rigidities on the mechanical behaviour of woven fabric, further to an extension in 45. Finally, by basing on phenomenological approach, a hyperelastic behaviour law is proposed. This model is implanted in a routine Vumat. It is identified from the tensile and the shearing tests and validated by certain cases of composite reinforcement forming
Barrero, Daniel. "Simulation et visualisation de phénomènes naturels pour la synthèse d'images." Toulouse 3, 2001. http://www.theses.fr/2001TOU30001.
Guilminot, Virginie. "La synthèse d'image animée : au-delà d'une simulation réaliste." Paris 8, 1996. http://www.theses.fr/1996PA081159.
A majority of 3d films and computer graphics respect a realistic aesthetic. On one hand, I will analyse why such totally made images initiate a film or reality and on the other hand, I will try to offer alternativity in order to create an other aesthetic, not being realistic. Softwares need numerous scientific formulas, therefore the author, while manipuling it, will be the main actor to change the situation. This is the main point. Realism exists in every 3d application, such as research, tv, cinema, fiction, school and even often in creation. A few artists managed to escape from realism, i. E. : Joan Stavely, Tamas Waliczky or Michel Bret. Each has its own way of working but they all aim at the same: not to reach realistic simulation. I agree on this point and illustrate my thinking, I made three 3d films with more sensitivity than technical challenge. It is possible to avoid the trap of realism. Indeed, by manipulating and divert the software, one can obtain different 3d computer graphics. Step by step, a new approach to handle and to develop tools apears, and thanks to this, authors can create films other than realistic.
Nguegang, Bertrand Vidal. "Contribution à la simulation numérique du couplage thermomécanique en grandes déformations : Application à la simulation en mise en forme des structures volumiques." Dijon, 1996. http://www.theses.fr/1996DIJOS022.
Corvisier, Philippe. "Ecoulement de fluides thixotropes dans des conduites droites ou présentant des singularités." Nancy 1, 2001. http://www.theses.fr/2001NAN10188.
The aim of this study is to put the focus on the interaction between the reorganization of the internal structure of a thixotropic fluid and the velocity field. Three cases were considered : a flow in a straight pipe, an entry flow and a start up flow. Velocity profiles were measured by particle image velocimetry (PIV). A flatness of velocity profiles, large vortex zones and a plug flow were observed. Then, a rheological study was conducted. It shows that a modified Quemada model with a fractional kinetic for the structural parameter l could be used. Moreover, to have a better understanding of the observed phenomenon in the pipe and to generalize the results, numerical simulations were performed. The finite volume code Fluent 4. 5 was adapted to deal with thixotropy by adding user defined subroutines. A good agreement between numerical and experimental results was observed. Moreover, the flow development was investigated by the analysis of the structural field
Rohani, Seyed Yahya. "Simulation numérique du comportement des matériaux granulaires." Metz, 1995. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/1995/Rohani.Seyed_Yahya.SMZ9541.pdf.
The theory of continuous media is not sufficient to explain the behaviour of granular materials, so it is necessary to consider the discrete nature of such media. A method that answers such questions is the distinc element method. The numerical simulation of the behaviour of Schneebeli analogical material (2D) and of granular materials (3D) is done by the distinct element method and by using the trubal program in order to reproduce numerically, certain experimental tests of the characterization of granular materials. The biaxial compression test and the simple shear test are done with rolls of PVC and glass and the trixial test is simulated with glass balls. The experimental results validate the method used and enable us to obtain the characteristic parameters of materials by different kinds of loading. The exploitation of numerical results highlights the fundamental role of the intergrain friction and the material density in order to characterize the granular media, enabling the analysis of the phenomenon of dilatance, localization and shear band. Finally, we applied this study to the behaviour of granular materials under push and trust effects, and in the case of ensiled materials
Zhang, Cun-Xiao. "Simulation numerique d'ecoulement turbulents autour d'un obstacle." Nantes, 1991. http://www.theses.fr/1991NANT2061.
Koval, Junior Georg. "Comportement d’interface des matériaux granulaires." Paris Est, 2008. http://pastel.paristech.org/4192/01/KOVAL.pdf.
In this thesis, we analyze the interface behavior of granular materials, and particularly the phenomenon of shear strain localization in the vicinity of a wall. Using an annular geometry with imposed shear velocity and confining pressure, we compare experimental and numerical approaches to describe this behavior. The experimental approach is composed of experiments with model materials in two annular simple shear devices (ACSA and mini-ACSA). We connect measurements of shear strain of the granular medium, obtained by correlation imaging velocimetry (ACSA) and by magnetic resonance imaging (mini-ACSA) to global measurements of the stress and volume variations. The numerical approach consists of two-dimensional discrete simulations (molecular dynamics). We study the influence of the geometry and the surface roughness on the behavior of the granular interfaces. In simulation, we complete the study with the analysis of inertial effects
Lhuillier, Emmanuel. "Transports electronique dans les super-réseaux : applications aux détecteurs infrarouges à grandes longueur d'onde." Palaiseau, Ecole polytechnique, 2010. http://pastel.archives-ouvertes.fr/docs/00/52/86/65/PDF/THESE_EL.pdf.
The low flux infrared imaging needs performant high wavelength detectors. Quantum Well Infrared Photodetectors (QWIP), thanks to the maturity of GaAs, the possibility to adjust the detected wavelength on a large range and to realize large uniform matrix are good candidate for such applications. In order to validate this interest, we have performed an electro-optic characterization of a 15µm sample. These measurements have been used to simulate the performance of a camera based on this QWIP and used in a low infrared photons flux scenario. We predict that this QWIP would succeed. Nevertheless these simulations also underline the detrimental role of the dark current. Thus we have developed a simulation tool based on a hoping approach between localized states, which provide us a better understanding of the transport in these heterostructures. The code has in particular underlines the role plays by the electron –ionized impurities interaction, which make the dark current very sensitive to the doping profile. Using this tool we have designed new structures, with optimized doping profile, in which the scattering rate has been decreased by a factor two. Moreover we have identified a quantum origin to the plateau shape of the I(V) curve. This code is more generally a useful simulation tool for the transport in hétérostructures. The influence of growth defects (non ideal interface and disorder) has been quantized and we have performed the first evaluation of The R0A in a THz QCD. Finally non local transport effects have been investigated. Saw teeth observation on the I(V) curves have been modeled and their influence on the detectivty estimated
Schaeffer, Nicolas. "Modélisation et simulation numérique des phénomènes de nucléation et de croissance en écoulement confiné." Université de Marne-la-Vallée, 2001. http://www.theses.fr/2001MARN0129.
Petit, Nicolas. "Couplage des procédés d’adsorption sur charbon actif et de photocatalyse TiO₂ / UV pour l’élimination de composés organiques volatils." Rennes 1, 2007. http://www.theses.fr/2007REN1S137.
TiO2 / UV photocatalysis is an emerging technology for Volatile Organic Compounds degradation. However, industrial scale-up is limited by the lack of knowledge in process engineering. Moreover, the coupling with an adsorbent should allow taking the best from the respective advantages of each technique. Results and developed simulation tool enable to grasp in a new way the interaction between adsorption and photocatalysis. The study of two hydraulic modes, in tangential and filtering flow, led us to introduce, for the second one, an initiator to enhance the reaction kinetics. The sequenced operation of the adsorption / photocatalysis system allowed us to take advantage of the thermal desorption for a better effectiveness. So, the coupling of both technologies offers very interesting possibilities in the perspective of a use as an air treatment system
Gougeon, Ludivine. "Comparaison de schémas numériques pour la simulation d’écoulements turbulents réactifs." Orléans, 2007. http://www.theses.fr/2007ORLE2024.
Darlet, Ludovic. "Système de visualisation scientifique assistée par ordinateur." Université Joseph Fourier (Grenoble), 1995. http://www.theses.fr/1995GRE10044.
Gaude, Daniel. "Modélisation et simulation de systèmes électromagnétiques à induction avec prise en compte des matériaux magnétiques et formulation par graphes de liens." Lyon 1, 1999. http://www.theses.fr/1999LYO10115.
Hénin, Jérôme. "Simulations moléculaires d'événements rares dans les systèmes biologiques membranaires." Nancy 1, 2006. http://www.theses.fr/2006NAN10007.
Slow or non spontaneously occurring processes involving biological macromolecules may still be studied through molecular dynamics simulations, provided that an algorithm promotes the exploration of a well–chosen reaction coordinate by the system. We implemented such an algorithm in the NAMD program, designed for large–scale simulations of biomolecular systems. We can then investigate the folding of peptides into alpha–helices, the recognition and association of proteins inside the membrane, as well as the specific transport of a small molecule, glycerol, by a bacterial transmembrane channel
Dautriat, Jérémie. "Comportement hydromécanique de roches réservoir sous contraintes : relations entre évolution de perméabilité et échelles des mécanismes d'endommagement." Palaiseau, Ecole polytechnique, 2009. http://tel.archives-ouvertes.fr/docs/00/38/57/77/PDF/Manuscrit_These_Dautriat.pdf.
The Understanding and the prevention of damage mechanisms, which have an impact on the kinetics of production and the rate of recovery, remain an outstanding issue in reservoir engineering. The aim of this study, based on the characterization of the hydromechanical behaviour of sandstone and carbonate rocks in 'reservoir conditions', is the identification of the local mechanisms responsible for changes in permeability measured macroscopically. The experimental work was performed with an original triaxial set-up, which allows measurements of the stress-induced permeability evolutions in the principal directions of the stress tensor. A first experimental campaign, consisting in hydrostatic and uniaxial compression tests, has been performed on Fontainebleau and Bentheim sandstones. In one hand, we showed that experimental end-effects might affect significantly the ‘classical' axial permeability measurements, and in the other hand, we have determined the impact of brittle failure on directional permeabilities. Compression experiments, following different stress-paths, were also carried out on a carbonate, the Estaillades limestone. In elastic deformation regime, the reduction of permeability was modelized by pore network simulations, based on 3D reconstructions of μ-tomography RX and a simplified representation of the pore space. While brittle fracture of carbonate samples induced slight permeability evolutions, at higher effective pressure, permeability drops can reach 90% to the initial values and are associated with mechanisms of pore collapse. The post-mortem analysis of deformed samples, coupled with digital image correlation methods, using both SEM and Optical acquisition devices, provide a better understanding of the role of the heterogeneities, identified at different scales, in the strain localization and their potential impacts on permeability changes at the sample scale
Sadeghi, Maryam. "Modeling and simulation of spiral concentrators." Doctoral thesis, Université Laval, 2021. http://hdl.handle.net/20.500.11794/69372.
Spiral concentrators are gravity separation devices used for the valorization of ores for which the specific gravity of the valuable minerals is significantly different from that of the gangue minerals. This is the case of iron ore processing discussed in this thesis. Spirals are preferred to other mineral separation devices because they are inexpensive, simple of operation, practically maintenance free, low energy demanding and do not require the use of reagents to separate minerals. Despite these appealing qualities and unlike flotation, few studies are dedicated to the analyze the spiral operation. Indeed, it is only recently that basic process analysis has shown that spirals fail to recover coarse dense mineral particles to the heavy product. It has also been recently found that wash water, as the main control variable for the operation of the studied spirals, is partly responsible for the loss of coarse valuable particles. To make up for this loss and to maintain a satisfactory operation of spirals, other control variables such as the concentrate cutter openings and position of the splitter gates at the spiral discharge should be used. The study of alternative control strategies for spirals implies testing these strategies in the industrial environment, which is practically impossible considering that the operation of mineral processing plants is subjected to constraints imposed on the production and on the quality of the plant product. Besides, the impact of disturbances due to ore variations and/or mechanical problems in the plant is unavoidable. Testing new control strategies in pilot plant is possible but it is certainly costly if one can find a pilot plant equipped for such testing. Plant operators are thus seeking for rapid and inexpensive approaches to carry out such investigation to identify strategies that can subsequently be safely tested in a plant. Process simulation offers this possibility, but a literature survey rapidly revealed the absence of simulation tools for spirals and more particularly for gravity separation circuits that use spiral concentrators. The first step in building such circuit simulator is to find or develop mathematical models for the units of the circuit. With the objective of testing control strategies, it is thus important that the model to be developed be able to account for the usual spiral operating variables, namely the cutter opening, the discharge splitter position and the wash water addition. The objective of this research project is to propose such model for spirals. A mathematical model is therefore described to predict the trajectory of particles distributed in mineral/size classes as they flow down a spiral. This is achieved here by introducing the new concept of Particle Displacement Functions (PDF) in spiral modelling to describe the movements of the particles flowing down the spiral. The model is calibrated using data generated from tests conducted on a pilot-scale test rig built around a Mineral Technologies WW6+ spiral, installed in the Mineral Processing Laboratory of Université Laval. The model is further validated with data obtained from a WW6E spiral operated at COREM. The test rig commissioned at Laval University uses a controlled wash water distribution within the spiral turns to overcome the observed problem of unequal wash water distribution when using the spiral built-in wash water distribution system. The test rig is also designed to sample simultaneously the product from each concentrate cutter of the spiral, so that the progress of the heavy mineral concentration down the spiral can be monitored. This information can be used to calibrate the model. The calibrated spiral simulator predicts adequately the spiral response to changes in the states of the operating variables. The model can simulate a cleaner spiral operation although it is calibrated using data collected from a rougher spiral operation. The proposed model is ready to be implemented into a simulator for an iron ore processing plant, although work remains to be done to finalize the calibration methodology to improve the prediction of the mineral size distribution in the spiral middling stream.
Philippe, Jean-Robert. "Contribution des modèles mécaniques textiles à la simulation graphique des étoffes." Saint-Etienne, 2002. http://www.theses.fr/2002STET4010.
This thesis deals with development of a mechanical and graphical model of woven fabrics, dedicated for the reproduction of morphological diversity of real fabric drapes. Two means of control are proposed : the first one consists of a representation of the non linear behaviour by a fuzzy model. In this case, mapping between inputs states and outputs is expressed by fuzzy rules, while the second consists of a mechanical implementation of the model. Two different startegies are proposed, leading to similar geometrical solutions, whatever the mechanical properties of studied fabrics may be
Le, Bodic Laurent. "Approche de l'évaluation des systèmes interactifs multimodaux par simulation comportementale située." Brest, 2005. http://www.theses.fr/2005BRES2006.
The Phd thesis is a contribution to evaluation of multimodal interactive systems. More particularly, we propose an approach of the evaluation of theses systems by a behavorial and located simulation. Such a study requires the use of a virtual actor, registered in a virtual environment. Its interaction with a virtual interactive system is used as a representation of a possible man-machine communication. The people in charge of the development use then the usability problems, detected in the virtual world, as a source of investigations to increase the efficiency of their prototypes. Modeling that we propose lies on the interaction of three functional bricks, which are : Models of environment, which influence user in his decision-making and which interacts with him (avoidance, displacement, etc. ). Model describing interactive systems which, by their characteristics, allows and guides the dialogue. Model of users, reproducing human decision with mixing of cognitive and perceptive aspects. This virtual user, by his characteristics, his history, interacts with environment and interactive system through the realization, in a virtual world, of a scenario of evaluation. This study is concluded by the introduction of the software demonstrator SIHMM and the study from its operational validity. This one is examined through the correlation of reals and virtuals experiments. From this one, we determine the potential use of the simulation in the phases of development, of interactive systems and open prospects on the future use of the simulation which we wish to develop
Malak, Jinane. "Modélisation par simulation numérique du fonctionnement mécanique de la fibre myocardique." Paris 12, 1988. http://www.theses.fr/1988PA120046.