Tesis sobre el tema "Théorie du transport – Modèles mathématiques"
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Allemand, Thibaut. "Modèles mathématiques pour les gaz quantiques". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2010. http://tel.archives-ouvertes.fr/tel-00548177.
Texto completoBoulanouar, Mohamed. "Transport - théorie et applications à la dynamique des populations cellulaires". Poitiers, 1997. http://www.theses.fr/1997POIT2282.
Texto completoDolbeault, Jean. "Analyse de modèles de la physique mathématique". Paris 9, 1991. https://portail.bu.dauphine.fr/fileviewer/index.php?doc=1991PA090013.
Texto completoM'madi, Issimail Mohamed Mouneime. "Théorie mathématique du transport topologique dans des modèles unitaires sur réseaux". Thesis, Toulon, 2019. http://www.theses.fr/2019TOUL0015.
Texto completoWe study certain discrete quantum dynamical systems which are described by unitary operators U acting on the space of square integrable functions defined on the vertices of a countably infinite graph. For initial conditions x the orbits of the system are defined by the iterations Unx for integer n. We consider classes of operators U which depend on parameters. We are interested in topological spectral properties meaning that they are characterized by integers which depend continuously on the parameters of the system. We answer questions which are based on recent observations and applications in physical and information sciences. We state and prove proper mathematical results which apply to some of these observations. In this the sis we present four results: in one spatial dimension and for a class of quantum walks we proved the existence of eigenvalues which are constant with respect to continuous and compact perturbations. In two dimensions we have obtained results on occurrence of stable absolutely continuous spectrum covering the whole unit circle for three different lattice models. We employed several mathematical tools: We used the theory of fibered operators to exhibit systematically the spectral properties of translation invariant operators U. For our operator topological considerations, we put to use the class of Fredholm operators and in particular the complete characterization of its connected components by the index. For the case of the constant eigenvalues we proved a non-trivial and explicit lower bound on their number using the index theorem for Toeplitz operators. We employed the theory of the relative index of a pair of orthogonal projections for our study of the full absolutely continuous spectrum. For each of the three cases we established its non-triviality for a pair involvingU, and then made use of recently proved results concerning the implications on the spectrum of U
Jimenez, Chloé. "Optimisation de problèmes de transport". Toulon, 2005. http://www.theses.fr/2005TOUL0005.
Texto completoThe main issue of the thesis is the study of the asymptotic behaviour of optimal transportation problems. Such problems occurs in economy and signal theory. Each of them consists in finding the best discrete measure u wich minimizes the transport to an absolute continuous measure f, subject to a constraint of the kind H(u)£m where H is a given entropy functional. In a first step, we study the case where f is a uniform density on a cube and H(u)=S (u(x))a with aÎ[0,1[. In the general case, we reduce the question of the asymptotic behaviour to the description of the G-limit of a suitable functionnal naturally associated to the Wasserstein distance. In the second part of the thesis, we present new applications of transport problems with time depending cost. The particular case of homogeneous cost (depending only on the average speed) allows us to write optimality conditions for the Wasserstein transport Wp (p>1) as a system of equations (eikonal-diffusion) written in the sense of measures. This generalizes the results obtained in the case p=1 ( L. Evans and W. Gangbo, G. Bouchitté and G. Buttazzo) and those of Brenier (p>1) to the case where the transported measures are singular
Ginzbourg, Irina. "Les problemes de conditions aux limites dans les methodes de gaz sur reseaux a plusieurs phases". Paris 6, 1994. http://www.theses.fr/1994PA066372.
Texto completoCausse, Anne. "La valeur du temps de transport : de l'usage des théories micro-économiques de l'affectation du temps dans les modèles désagrégés aléatoires de transport : prévision de trafic, évaluation de projet". Montpellier 1, 1999. http://www.theses.fr/1999MON10039.
Texto completoEl, Hajjj Raymond. "Etude mathématique et numérique de modèles de transport". Toulouse 3, 2008. http://thesesups.ups-tlse.fr/353/.
Texto completoThis thesis is decomposed into three parts. The main part is devoted to the study of spin polarized currents in semiconductor materials. An hierarchy of microscopic and macroscopic models are derived and analyzed. These models takes into account the spin relaxation and precession mechanisms acting on the spin dynamics in semiconductors. We have essentially two mechanisms : the spin-orbit coupling and the spin-flip interactions. We begin by presenting a semiclassical analysis (via the Wigner transformation) of the Schrödinger equation with spin-orbit hamiltonian. At kinetic level, the spinor Vlasov (or Boltzmann) equation is an equation of distribution function with 2x2 hermitian positive matrix value. Starting then from the spinor form of the Boltzmann equation with different spin-flip and non spin-flip collision operators and using diffusion asymptotic technics, different continuum models are derived. We derive drift-diffusion, SHE and Energy-Transport models of two-components or spin-vector types with spin rotation and relaxation effects. Two numerical applications are then presented : the simulation of transistor with spin rotational effect and the study of spin accumulation effect in inhomogenous semiconductor interfaces. In the second part, the diffusion limit of the linear Boltzmann equation with a strong magnetic field is performed. The Larmor radius is supposed to be much smaller than the mean free path. The limiting equation is shown to be a diffusion equation in the parallel direction while in the orthogonal direction, the guiding center motion is obtained. The diffusion constant in the parallel direction is obtained through the study of a new collision operator obtained by averages of the original one. Moreover, a correction to the guiding center motion is derived. .
Preux, Christophe. "Modélisation et calcul du transfert de masse et de chaleur dans un milieu poreux réactif en évolution structurale et applications". Bordeaux 1, 2006. http://www.theses.fr/2006BOR13250.
Texto completoAjmone, Marsan Giulia. "Nouveaux paradigmes et méthodes mathématiques pour systèmes complexes dans l'économie comportementale". Paris, EHESS, 2009. http://www.theses.fr/2009EHES0139.
Texto completoThis dissertation is devoted to the mathematical investigation of properties of complex socio-economic systems, where individual behaviors, and their interactions, exert a crucial influence on the overall dynamics of the whole system. In order to understand the importance of such an investigation, it is necessary to briefly analyze some conceptual aspects relating to the interaction between applied mathematics and socio-economic sciences. The main issue in this field consists in coupling the usual qualitative interpretation of socio-economic phenomena with an innovative quantitative description by means of mathematical equations. This dialogue, however difficult, is necessary to reach a deeper understanding of socio-economic phenomena, where deterministic rules may be stochastically perturbed by individual behaviors. The difficulty mostly stems from the fact that the behavior of socio-economic systems, where the collective dynamics differ from the sum of the individual behaviors, is aparadigmatic example of a complex system. The mathematical framework presented in this dissertation is built by suitable developments of the so-called mathematical kinetic theory for active particles, which proved to be a useful reference for applications in many fields of life sciences. The description of a system by the methods of the mathematical kinetic theory essentially implies the definition of the microscopic state space of the in¬teracting entities and of the distribution function over this state space
Moussa, Ibrahim. "Modèles de résolution approchée et efficace pour les problèmes des réseaux de transport et de télécommunication". Thesis, Amiens, 2015. http://www.theses.fr/2015AMIE0009/document.
Texto completoThis thesis focuses on solving combinatorial optimization problems NP-hard using approximate solving methods. Two practical application areas are targeted here, firstly the general problem of vehicule routing network with a variant specifically with planning tours with a vehicle team, on the other hand the multicast session management problem on a telecommunications network, addressed by the broader perspective of clustering in a bipartite graph. Both applications are obviously of interest both from the fundamental point of view for the resolution methods that must always progress facing new challenges, from the point of view of potential industrial benefits. The resolution of such problems usually has two phases: initially it comes to define one or more mathematical models to compare possibly to choose the most effective according to the available resolution tools; secondly it is possible to use a generic resolution paradigm, such as a linear programming solver, or specialize an algorithm by including specific heuristics and knowledge to optimize its performance. This thesis is in this second approach. This is often necessary when the problems addressed become complex and / or large and that we need to be designing more efficient algorithms
Mohamed, Yahya. "Théorie spectrale d'opérateurs symétrisables non compacts et modèles cinétiques partiellement élastiques". Thesis, Besançon, 2015. http://www.theses.fr/2015BESA2044/document.
Texto completoThis thesis is devoted to spectral theory of party elastic neutron transport equations introduced in 1974 by physicists E. LARSEN W and PF ZWEIFEL. The collision operator is then the sum of an inelastic part (corresponding to classical neutron transport models) and an elastic part that induces new spectral phenomena to be studied. The objective of this thesis is the analysis of their asymptotic spectrum (the part of the discrete spectrum that determines the time asymptotic behavior of the associated Cauchy problems). The spectral study of these partly elastic models involves spectral properties of bounded non-compact and symmetrizable operators. Thus the first part of the thesis deals with spectral theory of non compact symmetrizable operators on Hilbert spaces. We give a series of functional analytic results on these operators. In particular we give a method which provides us with all the real eigenvalues located outside the essential spectral disc and provide variational characterizations of these eigenvalues. The second part of the thesis focuses on spectral analysis of partly elastic isotropic and space homogeneous kinetic models (i.e. the cross sections depend only on speed modulus). Among other things, we show that the asymptotic spectrum consists at most of isolated eigenvalues with finite algebraic multiplicity. We also show that this point spectrum is real. Further we show that the number of real eigenvalues of the partly elastic transport operator increases indefinitely with the size of the spatial domain. We show also that all these eigenvalues tend to the spectral bound of the space homogeneous partly elastic operator when the size of domain tends to infinity. Most of these results are also extended to anisotropic models
Hfaiedh, Noureddine. "Nouvelle méthodologie de calcul de l'absorption résonnante". Université Louis Pasteur (Strasbourg) (1971-2008), 2006. http://www.theses.fr/2006STR13219.
Texto completoNgom, Timack. "Etude mathématique et numérique de quelques modèles d'écoulement en couches minces : application à la sédimentation". Chambéry, 2010. http://www.theses.fr/2010CHAMS017.
Texto completoIn this thesis, we have been interested in the primitive equations and Shallow Water equations in a mathematical and numerical context. Indeed, to obtain Shallow Water equations as well as primitive equations, we have considered a flow gouverned by Navier-Stokes equations and which takes place in a thin domain. This permits us to introduce a parameter epsilon, equal to the ratio between the charateristic depth and charateristic length of the domain, assumed to be small. To obtain the primitive equations we have neglected all the terms of epsilon order in the Navier-Stokes equations. Concerning the Shallow Water equations, we have done a formal asymptotic expansion and an averaging to respect the vertical component. For the mathematical study, the techniques we have used are based on a particular entropy, namely the BD entropy. For the numerical study, we have used the Finite Volumes method. We have adopted a VF Roe scheme which consists in solving a linearized Rieman's problem to compute the fluxes. Finally, we have combined the derivation techniques of Shallow Water equations and those of primitive equations to obtain, out of Vlasov equation and Navier-Stokes equations, a sediment transport model
Richebois, Edwige. "Calculs de coeur REP en transport 3D". Aix-Marseille 1, 1999. http://www.theses.fr/1999AIX11039.
Texto completoPerruchot-Triboulet, Sophie. "Validation et extensions du module d'autoprotection du code de transport neutronique multigroupe APOLLO 2". Aix-Marseille 1, 1996. http://www.theses.fr/1996AIX11047.
Texto completoMarcou, Olivier. "Modélisation et contrôle d’écoulements à surface libre par la méthode de Boltzmann sur réseau". Perpignan, 2010. http://www.theses.fr/2010PERP1001.
Texto completoThis PhD work considers the general problem of modelling and simulation of complex systems and deals with the domain of control and management of water resources. We propose here an original approach based on Lattice Boltzmann models (LB) for modelling free surface flows in irrigation canals, usually described with the non-linear shallow water equations. We adapted a bi-fluid model and studied the boundary conditions which allow to reproduce the geometry of a free-surface irrigation canal. Methods for estimating the desired hydraulic quantities were developed. We studied the behavior of submerged underflow gates, and we show that the model is able to spontaneously and correctly describe how the gates function in quite different situations. Validations were realized by comparing results from simulations and experimentations performed on a laboratory micro-canal facility. We also introduced sedimentation phenomena in the model and studied the influence of a sedimentation deposit on the flow. Comparisons between experimental and simulation results were also performed and converged
Bourgade, Jean-Pierre. "Obtention de modèles de diffusion à partir d'équations cinétiques : modélisation, étude mathématique et simulation". Phd thesis, Université Paul Sabatier - Toulouse III, 2004. http://tel.archives-ouvertes.fr/tel-00008808.
Texto completoMoller, Jean-Yves. "Eléments finis courbes et accélération pour le transport de neutrons". Electronic Thesis or Diss., Université de Lorraine, 2012. http://www.theses.fr/2012LORR0001.
Texto completoTo model the nuclear reactors, the stationnary linear Boltzmann equation is solved. After discretising the energy and the angular variables, the hyperbolic equation is numerically solved with the discontinuous finite element method. The MINARET code uses this method on a triangular unstructured mesh in order to deal with complex geometries (like containing arcs of circle). However, the meshes with straight edges only approximate such geometries. With curved edges, the mesh fits exactly to the geometry, and in some cases, the number of triangles decreases. The main task of this work is the study of finite elements on curved triangles with one or several curved edges. The choice of the basis functions is one of the main points for this kind of finite elements. We obtained a convergence result under the assumption that the curved triangles are not too deformed in comparison with the associated straight triangles. Furthermore, a code has been written to treat triangles with one, two or three curved edges. Another part of this work deals with the acceleration of transport calculations. Indeed, the problem is solved iteratively, and, in some cases, can converge really slowly. A DSA (Diffusion Synthetic Acceleration) method has been implemented using a technique from interior penalty methods. A Fourier analysis in 1D and 2D allows to estimate the acceleration for infinite periodical media, and to check the stability of the numerical scheme when strong heterogeneities exist
Moussa, Ibrahim. "Modèles de résolution approchée et efficace pour les problèmes des réseaux de transport et de télécommunication". Electronic Thesis or Diss., Amiens, 2015. http://www.theses.fr/2015AMIE0009.
Texto completoThis thesis focuses on solving combinatorial optimization problems NP-hard using approximate solving methods. Two practical application areas are targeted here, firstly the general problem of vehicule routing network with a variant specifically with planning tours with a vehicle team, on the other hand the multicast session management problem on a telecommunications network, addressed by the broader perspective of clustering in a bipartite graph. Both applications are obviously of interest both from the fundamental point of view for the resolution methods that must always progress facing new challenges, from the point of view of potential industrial benefits. The resolution of such problems usually has two phases: initially it comes to define one or more mathematical models to compare possibly to choose the most effective according to the available resolution tools; secondly it is possible to use a generic resolution paradigm, such as a linear programming solver, or specialize an algorithm by including specific heuristics and knowledge to optimize its performance. This thesis is in this second approach. This is often necessary when the problems addressed become complex and / or large and that we need to be designing more efficient algorithms
Ruiz, Thierry. "Eléments de modélisation et contribution expérimentale à l'étude du transport réactif dans un sol non saturé". Montpellier 2, 1998. http://www.theses.fr/1998MON20134.
Texto completoDuval, Fabien. "Modélisation du renoyage d'un lit de particules : contribution à l'estimation des propriétés de transport macroscopiques". Toulouse, INPT, 2002. http://www.theses.fr/2002INPT023H.
Texto completoAyyadi, Asma El. "Couplage des modèles classique-quantique. Simulation de la diode à effet tunnel". Toulouse, INSA, 2002. http://www.theses.fr/2002ISAT0026.
Texto completoThe principal objective of this work of thesis is to deal with the problem of coupling macroscopic fluid models (namely the Drift-Diffusion model) with quantum models (namely the Schrödinger equation) for those semiconductor devices where quantum effects play an important role only in a (small) portion of the domain. The hybrid classic-quantum models derived here are then coupled self-consistently with Poisson equation on the whole domain. The starting point for deducing the interface conditions is the kinetic-quantum coupling studied by Ben Abdallah ('98). The interface conditions are obtained with a diffusion limiting process. Second order interface conditions incorporating kinetic boundary layer corrections are derived. Two analytical formulae for the extrapolation coefficient appearing in the second order interface conditions, are proposed : the first one is based on the approximation of the albedo operator and the second one is an iteration procedure first introduced by Golse-Klar ('95). Resonant tunnelling diodes are simulated for two test cases of the results of the literature and the model shows good performance. Chapter 3 contains the extension of the results of the previous chapter to the case of Fermi-Dirac statistics and it follows the same structure. In the chapter 4 collisions are included in the quantum model via the Pauli equation. Appropriate interface conditions are deduced. Chapter 5 deals with the time dependant case with Boltzmann statistics
Daris, Thomas. "Étude des modèles de turbulence à quatre équations de transport pour la prévision des écoulements turbulents faiblement chauffés". Toulouse, ENSAE, 2002. http://www.theses.fr/2002ESAE0017.
Texto completoCapelle, Thomas. "Recherche sur des méthodes d'optimisation pour la mise en place de modèles intégrés de transport et usage des sols". Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAM008/document.
Texto completoLand use and transportation integrated (LUTI) models aim at representing the complex interactions between land use and transportation offer and demand within a territory. They are principally used to assess different alternative planning scenarios, via the simulation of their tendentious impacts on patterns of land use and travel behaviour. Setting up a LUTI model requires the estimation of several types of parameters to reproduce as closely as possible, observations gathered on the studied area (socio-economic data, transport surveys, etc.). The vast majority of available calibration approaches are semi-automatic and estimate one subset of parameters at a time, without a global integrated estimation.In this work, we improve the calibration procedure of Tranus, one of the most widely used LUTI models, by developing tools for the automatic and simultaneous estimation of parameters. Among the improvements proposed we replace the inner loop estimation of endogenous parameters (know as shadow prices) by a proper optimisation procedure. To do so, we carefully inspect the mathematics and micro-economic theories involved in the computation of the various model equations. To propose an efficient optimisation solution, we decouple the entire optimisation problem into equivalent smaller problems. The validation of our optimisation algorithm is then performed in synthetic models were the optimal set of parameters is known.Second, in our goal to develop a fully integrated automatic calibration, we developed an integrated estimation scheme for the shadow prices and a subset of hard to calibrate parameters. The scheme is shown to outperform calibration quality achieved by the classical approach, even when carried out by experts. We also propose a sensitivity analysis to identify influent parameters, this is then coupled with an optimisation algorithm to improve the calibration on the selected parameters.Third, we challenge the classical viewpoint adopted by Tranus and various other LUTI models, that calibration should lead to model parameters for which the model output perfectly fits observed data. This may indeed cause the risk of producing overfitting (as for Tranus, by using too many shadow price parameters), which will in turn undermine the models’ predictive capabilities. We thus propose a model selection scheme that aims at achieving a good compromise between the complexity of the model (in our case, the number of shadow prices) and the goodness of fit of model outputs to observations.Our experiments show that at least two thirds of shadow prices may be dropped from the model while still giving a near perfect fit to observations.The contribution outlined above are demonstrated on Tranus models and data from two metropolitan areas, in the USA and Europe
Mao, Lili. "Contribution à la résolution de l'équation de Boltzmann en multigroupe par les méthodes déterministes et Monte Carlo". Aix-Marseille 1, 1998. http://www.theses.fr/1998AIX11026.
Texto completoCatris, Stéphane. "Étude de contraintes et qualification de modèles à viscosité turbulente". École nationale supérieure de l'aéronautique et de l'espace (Toulouse ; 1972-2007), 1999. http://www.theses.fr/1999ESAE0018.
Texto completoLatocha, Vladimir. "Deux problèmes en transport des particules chargées intervenant dans la modélisation d'un propulseur ionique". Toulouse, INSA, 2001. https://tel.archives-ouvertes.fr/tel-00002194.
Texto completoThe modelling of the ionic thruster belonging to the SPT class raises many problems of plasma physics. We studied two of them, namely the electron transport and the computation of the electric potential. The electron transport is subject to the influence of the fields (magnetic and electric) set in the channel of the thruster on the one hand, and to the collisions of electrons with heavy species and at the walls on the oher hand. We participated to the development of a SHE model, wich is derived by performing an asymptotic analysis of the Boltzmann equation with a condition that models the reflection at the walls. This model allow to approximate the Electron Energy Distribution Function by solving a diffusion equation in the {position, energy} space, whose scales are macroscopic. More precisely, we extended an existing approach to the case where scattering against atoms are taken into account, as well as inelastic collisions at the walls. Then we compared the implementation of this model tot the results of a Monte Carlo simulation. We obtain similar results at a very reduced computational cost. This work lead to three publications, which are incorporated to the thesis. In a second stage, we studied the computation of the electric field in two dimensions. Due to the presence of a magnetic field, this problem gives rise to an anisotropic elliptic problem. Furthermore, the conductivities along the magnetic field and across the magnetic field lines can differ by several orders of magnitude. We implemented a finite volume scheme and we showed the numerical difficulties raised by such anisotropies. Hence, we improved this method by relating the solution of a highly anisotropic problem to a sequence of isotropic problems. This method proved to behabe well and we should be able to treat realistic cases shortly
Theissing, Simon. "Supervision en transport multimodal". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLN076/document.
Texto completoWithout any doubt, modern multimodal transportation systems are vital to the ecological sustainability and the economic prosperity of urban agglomerations, and in doing so to the quality of life of their many inhabitants. Moreover it is known that a well-functioning interoperability of the different modes and lines in such networked systems is key to their acceptance given the fact that (i) many if not most trips between different origin/destination pairs require transfers, and (ii) costly infrastructure investments targeting the creation of more direct links through the construction of new or the extension of existing lines are not open to debate. Thus, a better understanding of how the different modes and lines in these systems interact through passenger transfers is of utmost importance. However, acquiring this understanding is particularly tricky in degraded situations where some or all transportation services cannot be provided as planned due to e.g. some passenger incident, and/or where the demand for these scheduled services deviates from any statistical long term-plannings. Here, the development for and integration of sophisticated mathematical models into the operation of such systems may provide remedy, where model-predictive supervision seems to be one very promising area of application which we consider here. Model-predictive supervision can take several forms. In this work, we focus on the model-based impact analysis of different actions, such as the delayed departure of some vehicle from a stop, applied to the operation of the considered transportation system upon some downgrading situation occurs which lacks statistical data. For this purpose, we introduce a new stochastic hybrid automaton model, and show how this mathematically profound model can be used to forecast the passenger numbers in and the vehicle operational state of this transportation system starting from estimations of all passenger numbers and an exact knowledge of the vehicle operational state at the time of the incident occurrence. Our new automaton model brings under the same roof, all passengers who demand fixed-route transportation services, and all vehicles which provide them. It explicitly accounts for all capacity-limits and the fact that passengers do not necessarily follow efficient paths which must be mapped to some simple to understand cost function. Instead, every passenger has a trip profile which defines a fixed route in the infrastructure of the transportation system, and a preference for the different transportation services along this route. Moreover, our model does not abstract away from all vehicle movements but explicitly includes them in its dynamics, which latter property is crucial to the impact analysis of any vehicle movement-related action. In addition our model accounts for uncertainty; resulting from unknown initial passenger numbers and unknown passenger arrival flows. Compared to classical modelling approaches for hybrid automata, our Petri net-styled approach does not require the end user to specify our model's many differential equations systems by hand. Instead, all these systems can be derived from the model's predominantly graphical specification in a fully automated manner for the discrete time computation of any forecast. This latter property of our model in turn reduces the risk of man-made specification and thus forecasting errors. Besides introducing our new model, we also develop in this report some algorithmic bricks which target two major bottlenecks which are likely to occur during its forecast-producing simulation, namely the numerical integration of the many high-dimensional systems of stochastic differential equations and the combinatorial explosion of its discrete state. Moreover, we proof the computational feasibility and show the prospective benefits of our approach in form of some simplistic test- and some more realistic use case
Buguellou, Jean-Baptiste. "Micro-simulation des déplacements par système multi-agents : exploration multi-niveaux". Thesis, Tours, 2012. http://www.theses.fr/2012TOUR1801/document.
Texto completoFrom the perspective of best practice assessment of daily mobility, it should refocus the methods and tools for decision aid around the actors in travel: users. In this logic MICROBILIS model was developed to evaluate the adaptation strategies of users relative to their environmental transport. Three streams have been mobilized: the micro-simulation of assignment models, graph theory and multi-agent systems. The environment is modeled from a microscopic simulator of movements and a cellular graph, defining the network capacity. The simulations allow to find the empirical relationships of the dynamics of traffic on the sections and highlight upper capacity constraints at intersections. The transition to the simulation of a large network induces the complexity of the environment and the multiplication of particular cases. It was not possible to make this transition without reducing the initial assumptions, making it unrepresentative of reality
Moller, Jean-Yves. "Eléments finis courbes et accélération pour le transport de neutrons". Phd thesis, Université Henri Poincaré - Nancy I, 2012. http://tel.archives-ouvertes.fr/tel-00659200.
Texto completoWolff, Pierre. "Etude de la susceptibilité de diodes P. I. N. Soumises à une agression hyperfréquence". Montpellier 2, 1993. http://www.theses.fr/1993MON20032.
Texto completoBesnard, Katia. "Modélisation du transport réactif dans les milieux poreux hétérogènes. Application aux processus d'adsorption cinétique non linéaire". Rennes 1, 2003. https://tel.archives-ouvertes.fr/tel-00006040.
Texto completoAufrère, Loi͏̈c (19. "Etude de l'interaction gaz-paroi en régime hypersonique". Aix-Marseille 1, 2000. http://www.theses.fr/2000AIX11027.
Texto completoSun, Chenghai. "Contribution à l'étude de la thermodynamique des gaz sur réseaux : théorie et simulations". Vandoeuvre-les-Nancy, INPL, 1993. http://www.theses.fr/1993INPL012N.
Texto completoMellet, Antoine. "Etude asymptotique des équations cinétiques : applications à la modélisation des phénomènes de transport". Toulouse 3, 2002. http://www.theses.fr/2002TOU30192.
Texto completoLoyau, Hugues. "Etude numérique et modélisation algébrique des phénomènes d'anisotropie en turbulence statistique". Rouen, 1996. http://www.theses.fr/1996ROUES067.
Texto completoFinot, Aurélie. "Analyse mathématique des modèles cinétiques en présence d'un champ magnétique intense". Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0021.
Texto completoThis thesis proposes a mathematical analysis of kinetic models in the presence of strong magnetic fields.The objective of this project is the development of mathematical tools required for modelisation of fusion plasmas. The physical phenomena encountered in fusion plasmas involve disparate characteristic scales. The interaction between these orders of magnitude is an important issue and requires a multi-scale analysis. We appeal to homogenization techniques with respect to the fast rotation motion around the magnetic field lines.We study the finite Larmor radius regime for the Vlasov-Poisson system, in the framework of uniform magnetic fields, by appealing to gyro-average methods. We indicate the explicit expression of the effective advection field entering the Vlasov equation, after substituting the self-consistent electric field, obtained by the resolution of the averaged (with respect to the cyclotronic time scale) Poisson equation. We emphasize the hamiltonian structure of the limit model and present its properties : conservation of mass, of kinetic energy, of electric energy, etc.Then we generalize this study to general magnetic shapes. As before, the main properties of the limit model are emphasized : mass and energy balances, hamiltonian structure.We also take into account the collisional effects, under strong magnetic fields. After identifying the equilibria and the invariants of the average collision operator, we inquire about fluid models
Delage, Fabienne. "Etude de la fonction cinétique de dissolution d'un verre nucléaire". Montpellier 2, 1992. http://www.theses.fr/1992MON20159.
Texto completoVacus, Olivier. "Modélisation de la propagation d'ondes en milieu ferromagnétique". Châtenay-Malabry, Ecole centrale de Paris, 1997. http://www.theses.fr/1997ECAP0607.
Texto completoRobin, Yoann. "Transport optimal pour quantifier l'évolution d'un attracteur climatique et corriger ses biais". Electronic Thesis or Diss., Sorbonne université, 2018. http://www.theses.fr/2018SORUS071.
Texto completoThe climate system generates a strange attractor, described by a probability distribution, called the SRB measure (Sinai-Ruelle-Bowen). This measure describes the state and dynamic of the system. The goal of this thesis is first, to quantify the modification of this measure when climate changes. For this, the Wasserstein distance, stemming from the optimal transport theory, allows us determine accurately the differences between probability distributions. Used on a non-autonomous Lorenz toy model, this metric allows us to detect and quantify the alteration due to a forcing similar to anthropogenic forcing. This methodology has been applied to simulation of RCP scenarios from the IPSL model. The results are coherent with different scenarios. Second, the optimal transport gives a theoretical context for stationary bias correction: a bias correction method is equivalent to a joint probability law. A specific joint law is selected with the Wasserstein distance (Optimal Transport Correction method, OTC). This approach allows us extending bias correction methods in any dimension, correcting spatial and inter-variables dependences. An extension in the non-stationary context has been also developed (dynamical OTC method, dOTC). Those two methods have been tested in an idealized case, based on a Lorenz model, and on climate dataset (a regional climate simulation corrected with respect to the SAFRAN reanalysis)
Kosad, Youssouf. "Analyse spectrale et comportement asymptotique des solutions de quelques modèles d’équations de transport". Thesis, Université Clermont Auvergne (2017-2020), 2017. http://www.theses.fr/2017CLFAC056/document.
Texto completoThis thesis is devoted to the spectral theory and the time asymptotic behavior of the solution to Cauchy problems governed by various transport operators. In the first part, we discussed the spectral properties of streaming and transport operators in finite bodies with general boundary conditions. After establishing a compactness result essential to our analysis, we gave a fine description of the asymptotic spectrum of the transport operator. We also derive the regularity and the asymptotic behavior of the solution to Cauchy problem governed by the transport operator supplemented by bounce-back boundary conditions plus a compact operator in the space L^1. In the second part, we discussed the well-posedness and the asymptotic behavior of the solution to Cauchy problem governed by a singular transport operator. Unlike the first part, the analysis of this problem requires the use of Miyadera-Voigt perturbation theory for unbounded operators. In the last part of this work, a Cauchy problem governed by a linear operator introduced by Lebowitz and Rubinow describing a proliferating cell population structured by age and the cycle length was considered. Here our analysis was devoted to the case where the maximum cycle length is infinite
Grau, Ribes Alexis. "Mathematical models of transport phenomena in biological tissues". Doctoral thesis, Universite Libre de Bruxelles, 2020. https://dipot.ulb.ac.be/dspace/bitstream/2013/303032/4/contents.pdf.
Texto completoDoctorat en Sciences
info:eu-repo/semantics/nonPublished
Moussati, Ali El. "Nouveaux algorithmes pour la modélisation physique macroscopique électrique et électromagnétique des circuits microondesà l'état solide". Lille 1, 2004. http://www.theses.fr/2004LIL10081.
Texto completoBatany, Stéphane. "Influence d’un macropore sur l’écoulement et le transport de solutés en milieu poreux : expérimentations sur sol modèle macroporé et simulations numériques". Thesis, Paris Est, 2016. http://www.theses.fr/2016PESC1085/document.
Texto completoFlow and transport modeling through porous media is of primary concern nowadays, especially in order to progress in the understanding of pollutant transfers through soils. Soils present frequently heterogeneities such as macropores (caused by fauna, flora or cracks) and several numerical models use double or multi permeability concepts in order to take into account all flow types that may exist in such porous systems. Nevertheless, classical models seem underestimate the macropore effect on preferential flow and transport by restricting the preferential flow zone only to the volume occupied by the macroporosity. Various experimental studies prior to this thesis have questioned this hypothesis. This study proposes to understand the establishment of preferential flow and transport and in particular the mechanism of flow and solute exchanges between a synthetic macropore and a surrounding porous matrix in saturated condition. For this purpose, water tracing are realized for a model porous media constituted by glass beads, crossed by a synthetic macropore and implemented in laboratory columns. Breakthrough and transport in columns are characterized by monitoring the concentration at the end of the column by magnetic nuclear resonance. A numerical model developed on the basis of lattice-Boltzmann method is used to simul ate flow in macroporous system and identify preferential flow mechanisms at pore scale. Experimental data show that tracer transport is strongly dependent on injection flow rate and the diffusion coefficient in water. At high flow rate, the transport seems to occur exclusively in the macropore, with very little masse exchange with the porous matrix. At lower flow rates, the breakthrough exhibits an inflexion followed by a peak. The MRI images show a significant mass exchange of tracer between the macropore and the surrounding porous matrix. The numerical simulations are used to calculate the flow field in a porous system as a function of flow rate. They show that preferential flow is extended in porous matrix into a zone of same dimension the mean diameter of beads regardless of macropore size or injected flow rate, in the range of simulated flow rates. These experimental and numerical results show that macropore influence on transport should be extended through the surrounding porous matrix into a zone of the same size of grains diameter for flow and into a zone depending on diffusion coefficient as well as mean residence time of the studied tracer for solute transport
Denis-Vidal, Lilianne. "Identification d'un système biochimique, modélisation et contrôle d'un système de réacteurs". Compiègne, 1993. http://www.theses.fr/1993COMPD640.
Texto completoReveillon, Julien. "Simulation dynamique des grandes structures appliquée aux flammes turbulentes non-prémélangées". Rouen, 1996. http://www.theses.fr/1996ROUES071.
Texto completoMadaule, Éric. "Schémas numériques adaptatifs pour les équations de Vlasov-Poisson". Electronic Thesis or Diss., Université de Lorraine, 2016. http://www.theses.fr/2016LORR0112.
Texto completoMany numerical experiments are performed on the Vlasov-Poisson problem since it is a well known system from plasma physics and a major issue for future simulation of large scale plasmas. Our goal is to develop adaptive numerical schemes using discontinuous Galerkin discretisation combined with semi-Lagrangian description whose mesh refinement based on multi-wavelets. The discontinuous Galerkin formulation enables high-order accuracy with local data for computation. It has recently been widely studied by Ayuso de Dioset al., Rossmanith et Seal, etc. in an Eularian framework, while Guo, Nair and Qiu or Qiu and Shu or Bokanowski and Simarta performed semi-Lagrangian time resolution. We use multi-wavelets framework for the adaptive part. Those have been heavily studied by Alpert et al. during the nineties and the two thousands. Some works merging multi-scale resolution and discontinuous Galerkin methods have been described by Müller and his colleagues in 2014 for non-linear hyperbolic conservation laws in the finite volume framework. In the framework of relativistic Vlasov equation, Besse, Latu, Ghizzo, Sonnendrücker and Bertrand presented the advantage of using adaptive meshes. While they used wavelet decomposition, which requires large data stencil, multi-wavelet decomposition coupled to discontinuous Galerkin discretisation only requires local stencil. This favours the parallelisation but, at the moment, semi-Lagrangian remains an obstacle to highly efficient distributed memory parallelisation. Although most of our work is done in a 1d × 1v phase space, we were able to obtain a few results in a 2d × 2v phase space
Coste-Delclaux, Mireille. "Modélisation du phénomène d'autoprotection dans le code de transport multigroupe APOLLO2". Paris, CNAM, 2006. http://www.theses.fr/2006CNAM0516.
Texto completoThis document describes the improvements carried out for modelling the shelf-shielding phenomenon in the multigroup transport code APOLLO2. They concern the space and energy treatment of the slowing-down equation, the setting-up of quadrature formulas to calculate reaction rates, the setting-up of a method that treats directly a resonant mixture and the development of a "sub-group" method. We validate these improvements either in an elementary or in a global way. Now, we obtain, more accurate multigroup reaction rates and we are able to carry out a reference self-shielding calculation on a very fine multigroup mesh. To end, we draw a conclusion and give some prospects on the remaining work
Fricoteaux, Loïc. "Interaction informée par un système décisionnel pour un retour multimodal en environnement virtuel : application à la formation au transport fluvial". Compiègne, 2012. http://www.theses.fr/2012COMP2051.
Texto completoThis thesis deals with interaction between human and informed virtual environment (IVE). An IVE is a virtual environment including knowledge, which is, in our case, linked with virtual objects (Smart Objects). The purpose of this thesis is to enhance the coupling between human and IVE by allowing it to relevantly react to user’s behavior. To do so, we add to the IVE a decision-making module which is able to choose, in real time, a multimodal feedback (a set of aids) according to user’s activity which is observed by the system by using various sensors. We choose the belief function theory for decision-making in order to deal with the uncertainty and the incompleteness of collected data describing user’s behavior. In this way, our system brings an informed interaction: the reaction of the system to user’s actions is based on a priori knowledge combined with other knowledge acquired in real time. Thus, we bring a personalized interaction, adapted to each user, to increase its efficiency. The decision-making module includes an evidential network with conditional belief functions allowing graphically representing influences, a priori known, between different variables of the system. Input variables correspond to data collected in real time about the user: his/her actions and physiological state. These data can be uncertain (ex: data coming from sensors with some reliability) or incomplete (ex: failure of one of the sensors). The belief function theory allows us to represent these data with the uncertainty and the ignorance which are associated. These beliefs are then propagated in the evidential network to obtain, in output, a belief on the utility of the triggering for each available multimodal aid. The choice concerning the display of a set of multimodal aids, among those having an important utility, is done by solving a constraint satisfaction problem. Indeed, the set of multimodal aids to choose must respect a set of constraints which are a priori or dynamically set up. This allows ensuring the adequacy of the chosen solution with the system (ex : some aids can be incompatible with each other) and the adequacy with the user (ex : user’s sensory canals should not be overloaded with too many aids). Depending on the complexity of the problem, a good solution, without guarantee about its optimality, is computed by a genetic algorithm so as to be able to propose a feedback in a short due time. An information file for each user is created a priori and then updated by the system according to an estimation of the user’s preferences about the aids. These preferences are respected at best for the choice of the aids. This work has been applied to a fluvial navigation simulator in order to bring a training module allowing giving a personalized interaction to the learners with the simulator. The learner’s behavior is interpreted by the system (actions on ship controls, navigation errors determined from an estimation of the future position of the boat, stress level, etc. ) and with these data the decision-making system determines the most appropriate multimodal feedback according to the current situation. The aids proposed can be, for example, visual assistances, audio messages and simplifications of the navigation conditions in order to help the learner to anticipate the maneuvers to do. On the contrary, in the case of experienced learners, the decision-making system will rather choose to remove assistances and to increase the navigation complexity. This personalization of the feedback for each learner brings autonomy in the training allowing a trainer to follow several learners at the same time. Other applications of our work could be considered such as, for example, driving assistance in augmented reality. An experiment has been realized to evaluate the contribution of our system for learners of different levels. Our system has been compared to a system without aids (control system) and to a system with non-adaptive aids. The results show that, between the beginning and the end of the training, novice learners obtained a two-time greater score with our system in comparison with the control system. The system providing always the same aids (training without adaptation) did not allow the learners to improve themselves. The learners’ questionnaire answers and the trainers’ comments show a real interest of our approach