Rozprawy doktorskie na temat „Stabilité en temps long”
Utwórz poprawne odniesienie w stylach APA, MLA, Chicago, Harvard i wielu innych
Sprawdź 50 najlepszych rozpraw doktorskich naukowych na temat „Stabilité en temps long”.
Przycisk „Dodaj do bibliografii” jest dostępny obok każdej pracy w bibliografii. Użyj go – a my automatycznie utworzymy odniesienie bibliograficzne do wybranej pracy w stylu cytowania, którego potrzebujesz: APA, MLA, Harvard, Chicago, Vancouver itp.
Możesz również pobrać pełny tekst publikacji naukowej w formacie „.pdf” i przeczytać adnotację do pracy online, jeśli odpowiednie parametry są dostępne w metadanych.
Przeglądaj rozprawy doktorskie z różnych dziedzin i twórz odpowiednie bibliografie.
Kabakouala, André Bernard. "Comportement en temps long de quelques EDPs dispersives". Thesis, Tours, 2018. http://www.theses.fr/2018TOUR4001/document.
Pełny tekst źródłaNo summary available
Rodrigues, Luis Miguel. "Comportement en temps long des fluides visqueux bidimensionnels". Phd thesis, Grenoble 1, 2007. http://www.theses.fr/2007GRE10319.
Pełny tekst źródłaThis report investigates the long-time asymptotic behaviour of viscous bidimensional fluids, either homogeneous or weakly-inhomogeneous. Regarding homogeneous fluids, Thierry Gallay and C. Eugene Wayne have shown the major role of a family of self-similar solutions, the Oseen vortices, which attracts any solution of the Navier-Stokes equation with a finite measure as initial vorticity and non-zero circulation. Their result is non-explicit and the first task of this report is to make it explicit, getting this way a bound for the time-life of bidimensional turbulence. Then is shown the asymptotic stability of the Oseen vortices as density-dependent fluids, which also enables one to recover the result of Gallay and Wayne for slow weakly-inhomogeneous incompressible fluids. At last, it is proved that slow weakly-inhomogeneous compressible fluids, with zero circulation, behave asymptotically mainly as homogeneous fluids
Rodrigues, Luis Miguel. "Comportement en temps long des fluides visqueux bidimensionnels". Phd thesis, Université Joseph Fourier (Grenoble), 2007. http://tel.archives-ouvertes.fr/tel-00200818.
Pełny tekst źródłaFeng, Yuehong. "Stabilité de solutions régulières pour des systèmes d'Euler-Maxwell et de Navier-Stokes-Maxwell compressibles". Thesis, Clermont-Ferrand 2, 2014. http://www.theses.fr/2014CLF22484/document.
Pełny tekst źródłaThis thesis is essentially composed of two parts dealing with Cauchy problems and periodic problems. In the first part, we study the stability of smooth solutions near non constant equilibrium states for a two-fluid isentropic compressible Euler-Maxwell system.By classical energy estimates together with an induction argument on the order of the derivatives of solutions, we prove the existence and uniqueness of global solutions to the system when the given initial data are near the equilibrium states. We also obtain the asymptotic behavior of solutions when the time goes to infinity. In the second part, we consider the long time stability of the global smooth solutions for compressible Euler-Maxwell and Navier-Stokes-Maxwell systems in non isentropic case when the equilibrium solutions are constants. With the help of suitable choices of symmetrizers and energy estimates, we prove the existence and uniqueness of global solutions to the systems with given small initial data. Furthermore, using the Duhamel principle and the Fourier analysis tool, we obtain the decay rates of smooth solutions as the time goes to infinity
Rosas, Martinez Luis. "Study of two wave propagation problems in electromagnetic dispersive media : 1) Long-time stability analysis in Drude-Lorentz media; 2) Transmission between a slab of metamaterial on a dielectric". Electronic Thesis or Diss., Institut polytechnique de Paris, 2023. http://www.theses.fr/2023IPPAE011.
Pełny tekst źródłaThis PhD thesis addresses two independent problems related to wave propagation phenomena in dispersive media. In the first part, we investigate the long-time behavior of solutions of Maxwell’s equations in dissipative generalized Drude-Lorentz media. More precisely, we wish to quantify the loss in such media in terms of the decay rate of the electromagnetic energy for the corresponding Cauchy problem. This first part is in turn composed by two approaches. The first one, namely, the frequency dependent Lyapunov approach, consists in deriving a differential inequality (in time) for certain functionals of the solution, the Lyapunov functions L(k), where k is the spatial frequency. The stability estimates are then obtained from the time integration of the differential inequality. By developing this method, we obtain a polynomial stability result under strong dissipative assumptions. The second approach, the modal approach, exploits the spectral properties of the Hamiltonian operator appearing in the Cauchy problem. This last approach ameliorates the first one by considering weak dissipation assumptions. In the second part of the work, we are interested in the transmission problem of a slab of non-dissipative Drude metamaterial within a dielectric. In this context, we consider the TM two dimensional time-dependent Maxwell’s equations and we reformulate it into a Schrödinger equation whose Hamiltonian, A, is a unbounded self-adjoint operator. Fourier transform allow us to work with the reduced Hamiltonians A(k), k ∈ R. Finally, we are interested in the point spectrum of the reduced Hamiltonian which is related to the guided modes of the original problem. This study leads to a diseprsion relation whose difficulty lies in its highly non-linear character with respect to the spectral parameter. We prove the existence of a countable infinity of solution branches for the dispersion relation: the so-called dispersion curves. We give a precise analysis of these curves and enlighten the existence of guided waves which correspond to surface plasmons
Bui, Van Bien. "La stabilité du filtre non-linéaire en temps continu". Thesis, Nice, 2016. http://www.theses.fr/2016NICE4002/document.
Pełny tekst źródłaThe filtering problem consists of estimating the state of a dynamic, called signal which is often a Markov process, from the noisy observation of the past states. In this thesis, we consider a filtering model in continuous time for the diffusion process. The aim is to study the stability of the optimal filter with respect to its initial condition beyond the mixing (or quasi – mixing) hypothesis for the transition kernel
Bhiri, Bassem. "Stabilité et stabilisation en temps fini des systèmes dynamiques". Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0100/document.
Pełny tekst źródłaThis dissertation deals with the finite time stability and the finite time stabilization of dynamic systems. Indeed, it is often important to ensure that during the transient regime, the state trajectories do not exceed certain predefined limits in order to avoid saturations and excitations of the nonlinearities of the system. Hence the interest is to study the stability of the dynamic system in finite time. A dynamic system is said to be stable in finite time (FTS) if, for any initial state belonging to a predetermined bounded set, the state trajectory remains within another predetermined bounded set for a finite and fixed time. When the system is disturbed, it is called finite time boundedness (FTB). In this manuscript, the goal is to improve the results of finite time stability used in the literature. First, new sufficient conditions expressed in terms of LMIs for the synthesis of an FTB controller by dynamic output feedback have been developed via an original descriptor approach. An original method has been proposed which consists in using a particular congruence transformation. Second, new LMI conditions for the study of finite time stability and finite time stabilization have been proposed for disturbed and undisturbed nonlinear quadratic systems. Third, to obtain even less conservative conditions, new developments have been proposed using polynomial Lyapunov functions
Amini, Hadis. "Stabilisation des systèmes quantiques à temps discrets et stabilité des filtres quantiques à temps continus". Phd thesis, Ecole Nationale Supérieure des Mines de Paris, 2012. http://pastel.archives-ouvertes.fr/pastel-00803170.
Pełny tekst źródłaVeysset, Jérémy. "Simulation des grands espaces et des temps longs". Thesis, Paris, ENMP, 2014. http://www.theses.fr/2014ENMP0083/document.
Pełny tekst źródłaFluid-Structure Interaction (FSI) describes a wide variety of industrial problems arising in mechanical engineering, civil engineering and biomechanics. In spite of the available computer performance and the actual maturity of computational fluid dynamics and computational structural dynamics, several key issues still prevent accurate FSI simulations.Two main approaches for the simulation of FSI problems are still gaining attention lately: partitioned and monolithic approaches. Results in the literature show that the partitioned approach is accurate and efficient but some instabilities may occur depending on the ratio of the densities and the complexity of the geometry. Monolithic methods are still of interest due to their capability to treat the interaction of the fluid and the structure using a unified formulation. In fact it makes the build up of a FSI problem easier as the mesh do not have to fit the geometry of the solids and the transfers are treated naturally.The software Thost has been created based on these analyzes. Thost is a 3D aerothermal numerical software. It has been developped for the numerical simulation of industrial processes like the heating in industrial furnaces as well as quenching. Its target is to model numericaly the thermal history of the industrial pieces in their environment without using any transfer coefficient. However the computational costs are still high and therefore the software is not fully efficient from an industrial point of view to simulate, analize and improve complex processes. All the work in this PhD thesis has been done to reduce the computational costs and optimize the accuracy of the simulations in Thost based on innovatives numerical methods such as dynamic anisotropic mesh adaptation, stabilized finite elements methods and immersing the objects directly from their Computer Aided Design files
Zoghlami, Naïm. "Stabilité et stabilisation en temps fini des ystèmes dynamiques interconnectés et problème de consensus en temps fini". Thesis, Evry-Val d'Essonne, 2014. http://www.theses.fr/2014EVRY0023/document.
Pełny tekst źródłaThis manuscript is dedicated to the study of finite time stability and stabilization of interconnected dynamical systems and finite time consensus problem. After a general introduction, the first part of this thesis focuses on finite time stability and stabilization of perturbed systems and interconnected systems. The second part of this thesis is devoted to the problems of: finite-time consensus, average consensus and finite time stabilization of multi-agent systems. This concept has been addressed by targeting non-linear controlled dynamical systems: with and without drift term. Some protocols are proposed to solve the finite time consensus problem. Many applications and simulations are illustrated
Dauphin, Gabriel. "Application des représentations diffusives à temps discret". Phd thesis, Télécom ParisTech, 2001. http://tel.archives-ouvertes.fr/tel-00005780.
Pełny tekst źródłaLe première partie consiste en la mise en place des représentations diffusives à temps discret. Certains filtres non-relationnels, notamment les différences frationnaires, sont une agrégation continue de dynamiques purement amorties. Les représentations diffusives s'appliquent à toutes les discrétisations de l'intégration fractionnaire y compris celles pour lesquelles la fonction de transfert n'est pas connue analytiquement. Les filtres diffusifs peuvent être réalisés par un système de dimension infinie. Cette structure est un cadre adapté à l'approximation par un filtre relationnel, à l'analyse asymptotique aux temps longs et à l'élaboration d'un critère de dissipativité.
La deuxième partie consiste à appliquer ces outils pour l'étude des couplages formés de filtres diffusifs et de filtres rationnels positifs. L'application d'un critère de Nyquist prouve la stabilité énergétique. Ces couplages sont en fait la somme d'une partie entière et d'une partie diffusive, ce résultat de décomposition montre que certains couplages sont stables EBSB (entrée-bornée, sortie-bornée). La dissipativité de la réalisation diffusive ainsi que le lemme de Kalman-Yacubovich-Popov montrent notamment la stabilité interne de ces couplages ; une démonstration originale du caractère asymptotique de la stabilité interne est ainsi proposée. Les approches utilisées pour prouver ces stabiblités permettent une analyse asymptotique aux temps longs.
Farhat, Hassan. "Prise en compte des temps et des déplacements en stabilité des pentes". Lyon, INSA, 1990. http://www.theses.fr/1990ISAL0092.
Pełny tekst źródła[The aim of this work LS to propose new methods of calculation in slope stability analysis. First, a bibliographical review, on shear behaviour of soils and methods of slope stability analysis, shows the advantage of a displacement formulation. Then, two methods of calculation were proposed. The first takes into account the displacements measured by inclinometers to follow the evolution of a slope. The second method is more general. It permits one to follow the evolution of a slope (stresses and displacements) as a function of the varying boundary conditions. Laws of creep are introduced in the model. The displacement of the slope with time can be controlled. The two methods are validated by comparing the results of the calculation with the sliding measurements of the experimental embankment of Sallèdes (Puy de Dôme) and the sliding of Campagna (Italy). ]
Agulhari, Cristiano Marcos. "Stabilité et commande des systèmes linéaires variant dans le temps aux paramètres incertains". Phd thesis, INSA de Toulouse, 2013. http://tel.archives-ouvertes.fr/tel-00822689.
Pełny tekst źródłaSarmis, Merdan. "Etude de l'activité neuronale : optimisation du temps de simulation et stabilité des modèles". Thesis, Mulhouse, 2013. http://www.theses.fr/2013MULH3848/document.
Pełny tekst źródłaComputational Neuroscience consists in studying the nervous system through modeling and simulation. It is to characterize the laws of biology by using mathematical models integrating all known experimental data. From a practical point of view, the more realistic the model, the largest the required computational resources. The issue of complexity and accuracy is a well known problem in the modeling and identification of models. The research conducted in this thesis aims at improving the simulation of mathematical models representing the physical and chemical behavior of synaptic receptors. Models of synaptic receptors are described by ordinary differential equations (ODE), and are resolved with numerical procedures. In order to optimize the performance of the simulations, I have implemented various ODE numerical resolution methods. To facilitate the selection of the best solver, a method, requiring a minimum amount of information, has been proposed. This method allows choosing the best solver in order to optimize the simulation. The method demonstrates that the dynamic of a model has greater influence on the solver performances than the kinetic scheme of the model. In addition, to characterize pathogenic behavior, a parameter optimization is performed. However, some parameter values lead to unstable models. A stability study allowed for determining the stability of the models with parameters provided by the literature, but also to trace the stability constraints depending to these parameters. Compliance with these constraints ensures the stability of the models studied during the optimization phase, and therefore the success of the procedure to study pathogen models
Dauphin, Gabriel. "Application des représentations diffusives au temps discret". Paris, ENST, 2001. https://pastel.archives-ouvertes.fr/tel-00005780.
Pełny tekst źródłaBruno, Olivier. "Dynamiques transitoires et croissance économique : une tentative d'intégration entre court et long termes". Nice, 1998. http://www.theses.fr/1998NICE0010.
Pełny tekst źródłaThis work investigates the relationships between short-run and long-run. In order to do this, we study the possible impact of transient dynamics on steady-state equilibrium. First chapter has essentially a methodological device. We stress that the transient dynamics becomes neutral on long-run equilibrium with the development of stability analysis during the thrities. In a second chapter, we study equilibrium transitional dynamics. We retain endogenous growth models with convex technologies, two sectors and two capital goods. We emphasise that these models are issued from a canonical one (rebelo (1991) ) depending on the value of technological parameters. We underline that the counterpart of the endogeneity of growth is the exogeneity of income distribution. Indeed, the interest rate is determined by purely technological factors. Therefore, the transitional dynamics has no impact on steady-state equilibrium, that is predetermined by equilibrium rate of interest. At a last step, we stress that multiplicity of equilibria trajectory (the case of indetermination) not allows to break with the neutrality of transitional dynamics on long-run positions. The last chapter deals with disequilibrium transient dynamics (post-keynesian models of growth). We expound an original model assuming disequilibrium in dimension (i. E. Between the level of supply and demand) and disequilibrium in proportion (between the structure of supply and demand). We stress that a multiplicity of long-run equilibria occurs. The choice of one equilibrium between the existing equilibria depends now on short-run adjustment process. As a consequence, transitional dynamics has a qualitative impact on long-run equilibrium
Moulay, Emmanuel. "Une contribution à l'étude de la stabilité en temps fini et de la stabilisation". Phd thesis, Ecole Centrale de Lille, 2005. http://tel.archives-ouvertes.fr/tel-00114333.
Pełny tekst źródłaLa deuxième partie de ce mémoire est consacrée à la stabilisation en utilisant les fonctions de Lyapunov contrôlées. Une large part est dédiée à la stabilisation en temps fini.
Taousser, Fatima Zohra. "Analyse de stabilité des systèmes à commutations sur un domaine de temps non-uniforme". Thesis, Valenciennes, 2015. http://www.theses.fr/2015VALE0038/document.
Pełny tekst źródłaThis thesis deals with the stability analysis of switched systems that evolve on non uniform time domain by introducing the time scale theory. We are interested mainly in dynamical linear switched systems defined on particular time scale T = P{tσk ,tk+1} = ∪∞k=0[tσk, tk+1]. The studied system switches between a continuous-time dynamical subsystem on the intervals ∪∞k=0[tσk, tk+1[ and a discrete-time dynamical subsystem on instants ∪∞k=0{tk+1} (a discrete time) with a time-varying discrete step. In a first part, sufficient conditions are given to guarantee the exponential stability of this class of switched systems. Then necessary and sufficient conditions for stability are given by determining a region of exponential stability. In the second part, the stability of this class of switched systems with nonlinear uncertainties, is treated using majoration of the solution, and after that by introducing the approach of a common Lyapunov function. The third part is devoted to the consensus problem under intermittent information transmissions where the closed-loop multi-agent system can be represented as a switched system using a combination of linear continuous-time and linear discrete-time systems
Varoquaux, Gaël. "Sources atomiques pour senseurs inertiels interférométriques à long temps d'interrogation". Phd thesis, Université Paris Sud - Paris XI, 2008. http://tel.archives-ouvertes.fr/tel-00265714.
Pełny tekst źródłaFlouzat, Christophe. "Modulateurs sigma-delta passe-bande en temps continu". Paris 11, 2003. http://www.theses.fr/2003PA112339.
Pełny tekst źródłaShen, Dawei. "Problèmes de stabilité en relativité générale". Electronic Thesis or Diss., Sorbonne université, 2024. http://www.theses.fr/2024SORUS014.
Pełny tekst źródłaThis thesis is devoted to study the stability of particular solutions to Einstein vacuum equations: the Minkowski spacetime and Kerr black holes. More precisely, this thesis contains four main results. The first result concerns the stability of Minkowski spacetime outside an outgoing null cone and contains a generalization of the result of Klainerman-Nicolo. The second result shows the global nonlinear stability of the Minkowski space under the assumption of minimal decay on the initial data generalizing a result of Bieri. The third result provides a new proof of Kerr stability in external regions, obtained by Caciotta-Nicolo. The common feature of these three works is the application of the r^p-weighted estimate method introduced by Dafermos-Rodnianski, as an alternative to the vectorfield method, to obtain control of the curvature terms. The last result provides a construction of GCM hypersurfaces, which is a part of a sequence of five works (the four others are due to Klainerman-Szeftel and Giorgi-Klainerman-Szeftel) establishing Kerr stability for small angular momentum
Velleret, Aurélien. "Mesures quasi-stationnaires et applications à la modélisation de l'évolution biologique". Thesis, Aix-Marseille, 2020. http://www.theses.fr/2020AIXM0226.
Pełny tekst źródłaI describe the long term behavior of several processes that model the mechanisms of natural selection. In the cases under consideration, one can interpret those selective effects as a conditioning which introduces a bias on the dynamics of some « neutral » stochastic process. This process evolves in a potentially very general space, notably continuous and unbounded. By these means, one can characterize the dynamics of the whole profile of individuals in the population of study as well as the profile of an individual uniformly chosen in the population. One can naturally see in these descriptions some brutal transitions of the distribution laws as time evolves, which makes the analysis much trickier than for the models without conditioning. The first part of this thesis consists in setting the conditions under which one can prove results analogous to the notion of stationarity while taking the conditioning into account. The second part is dedicated to the application of these criteria for a diversity of models of populations under selection and their interpretation. Examples of application include the mobile optimum model for adaptation to environmental change, a group selection model and Müller's ratchet model that describes how the sub-population unaffected by deleterious mutations can maintain itself
Dupraz, Yannick. "Le développement économique en Afrique dans le temps long de I'histoire". Paris, EHESS, 2016. http://www.theses.fr/2016EHES0084.
Pełny tekst źródłaContending that the current economic situation of African countries south of the Sahara can partly be explained by their colonial past, this thesis studies Africa's economic development in the long run of history, notably through the comparison between French and British colonialism. The first chapter studies dynamically the functioning of colonial states in West Africa, using a new database on colonial public finances in 4 British and 9 French colonies. The second chapter analyses French and British colonial legacies in education, using the division of German Cameroon between the French and the British after World War I as a natural experiment to identify the effect of colonizer identity and its evolution throughout the 20th century. The third chapter ask what explains the decline of polygamy in West Africa in the 20th century, using the boom in public education expenditure in Cameroon in the 1950s to identify the effect of women's education on marriage market outcomes
Dib, Elias. "Analyse numérique du comportement mécanique en temps long des composites unidirectionnels". Thesis, Paris Est, 2016. http://www.theses.fr/2016PESC1107/document.
Pełny tekst źródłaFiber Reinforced Plastic materials (FRP) are beginning to find more and more applications in the civil engineering domain. Besides the use of FRPs for the reinforcement of existing structures, these materials are utilized quite often today for the construction of bridges and even for new buildings made entirely of FRPs. At the matter of fact, the light weight of composite materials is a considerable advantage compared to conventional materials such as steel or concrete. Another advantage is that they have outstanding fatigue and durability potential and that they are in general very tolerant to environmental effects such as UV radiations, moisture, chemical attack and extreme temperature variations. However, the lack of a comprehensive, validated, and easily accessible database for the durability of fiber-reinforced polymer composites as related to civil infrastructure applications is a critical barrier to their usage as main load bearing systems. The creep behavior of these materials and their failure under sustained loads remains an open research topic. This study gives a detailed analysis on the mechanical behavior of unidirectional fiber reinforced composites (UD FRP) subjected to different loading patterns (tension, compression, shear, and flexure). We develop two micromechanical models that allow us to analyze the instantaneous and the long term response of UD composites subjected to different load patterns. The first model is based on the shear-lag theory and the Beyerlein et al.[1998] developments while the second one is established using the finite element software Abaqus. A Comparative study between the two models allowed to validate the fundamental assumptions of the shear-lag theory (first model) as well as several numerical issues related to time integration and spatial discretization. The Monte Carlo method is used in order to account for the stochastic fiber strength and its impact on the ultimate tensile strength (short term) and creep (long term). A parametric investigation on the fiber type and load level/type on the short/long term behavior of UD composites is also presented
Toldo, Sandrine. "Convergence de filtrations ; application à la discrétisation de processus et à la stabilité de temps d'arrêt". Phd thesis, Université Rennes 1, 2005. http://tel.archives-ouvertes.fr/tel-00011277.
Pełny tekst źródłaFedelich, Bernard. "Trajets d'équilibre des systèmes mécaniques dissipatifs à comportement indépendant du temps physique". Marne-la-vallée, ENPC, 1990. http://www.theses.fr/1990ENPC9018.
Pełny tekst źródłaMalrieu, Florent. "Inégalités fonctionnelles et comportement en temps long de quelques processus de Markov". Habilitation à diriger des recherches, Université Rennes 1, 2010. http://tel.archives-ouvertes.fr/tel-00542278.
Pełny tekst źródłaHorsin, Romain. "Comportement en temps long d'équations de type Vlasov : études mathématiques et numériques". Thesis, Rennes 1, 2017. http://www.theses.fr/2017REN1S062/document.
Pełny tekst źródłaThis thesis concerns the long time behavior of certain Vlasov equations, mainly the Vlasov- HMF model. We are in particular interested in the celebrated phenomenon of Landau damp- ing, proved mathematically in various frameworks, foar several Vlasov equations, such as the Vlasov-Poisson equation or the Vlasov-HMF model, and exhibiting certain analogies with the inviscid damping phenomenon for the 2D Euler equation. The results described in the document are the following.The first one is a Landau damping theorem for numerical solutions of the Vlasov-HMF model, constructed by means of time-discretizations by splitting methods. We prove more- over the convergence of the schemes. The second result is a Landau damping theorem for solutions of the Vlasov-HMF model linearized around inhomogeneous stationary states. We provide moreover a quite large amount of numerical simulations, which are designed to study numerically the nonlinear case, and which seem to show new phenomenons. The last result is the convergence of a scheme that discretizes in time the 2D Euler equation by means of a symplectic Crouch-Grossmann integrator
Cavichioli, Gonzaga Carlos. "Analyse de stabilité et de performances d'une classe de systèmes non-linéaires à commutations en temps discret". Phd thesis, Université de Lorraine, 2012. http://tel.archives-ouvertes.fr/tel-00762873.
Pełny tekst źródłaCavichioli, Gonzaga Carlos Alberto. "Analyse de stabilité et de performance d'une classe de systèmes non-linéaires à commutations en temps discret". Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0086/document.
Pełny tekst źródłaIn this PhD thesis, several problems of stability analysis and control design of discrete-time switched nonlinear systems are addressed. As main contribution, a new class of Lyapunov functions which takes the nonlinearity into account has been proposed. We show that these functions are suitable to solve the classical stability analysis problem of linear systems connected to a cone bounded nonlinearity. Instead of the original Lyapunov Lur'e function, the assumptions about the nonlinearity variation are not required. Furthermore, the local stability analysis and control synthesis problems of Lur'e systems subject to control saturation are tackled by considering the level set of our function as an estimate of the basin of attraction. We expose that this estimate, which is given by non-convex and disconnected sets, is less conservative than ellipsoidal sets. We extend these results in order to deal with the problems of stability analysis and stabilization of discrete-time switched nonlinear systems. On one hand, we consider the case of arbitrary switching such that our sufficient conditions assure the properties of stability for all possible switching rules. In this framework, we highlight that our function is able to provide a suitable estimate of the basin of attraction. On the other hand, we tackle the problem of switching rule design aiming at the stabilization of discrete-time switched systems with nonlinear modes. We propose a switching strategy depending on the minimum of our switched Lyapunov Lur'e function. Hence, our framework leads to state space partitions, related to the mode activation, which are not restricted to conic sets, commonly exhibited by the switched quadratic functions approaches
Orlhac, Xavier. "Etude de la stabilité thermique du verre nucléaire. Modélisation de son évolution à long terme". Montpellier 2, 1999. http://www.theses.fr/1999MON20183.
Pełny tekst źródłaTobin-Daignault, Simon. "Le rôle de la mémoire à long terme dans la perception du temps". Doctoral thesis, Université Laval, 2015. http://hdl.handle.net/20.500.11794/26283.
Pełny tekst źródłaLagasquie, Gabriel. "Etude du comportement en temps long de processus de markov déterministes par morceaux". Thesis, Tours, 2018. http://www.theses.fr/2018TOUR4004/document.
Pełny tekst źródłaThe objective of this thesis is to study the long time behaviour of some piecewise deterministic Markov processes (PDMP). The flow followed by the spatial component of these processes switches randomly between several flow converging towards an equilibrium point (not necessarily the same for each flow). We will first give an example of such a process built in the plan from two linear stable differential equations and we will see that its stability depends strongly on the switching times. The second part of this thesis is dedicated to the study and comparison of two competition models in a heterogeneous environment. The first model is a probabilistic model where we build a PDMP simulating the effect of the temporal heterogeneity of an environment over the species in competition. Its study uses classical tools in this field. The second model is a deterministic model simulating the effect of the spatial heterogeneity of an environment over the same species. Despite the fact that the nature of the two models is very different, we will see that their long time behavior is very similar. We define for both model several quantities called invasion rates modelizing the growth (or decreasing) rate speed of a species when it is near to extinction and we will see that the signs of these invasion rates fully describes the long time behavior for both systems
Lafontaine, David. "Effets dispersifs et asymptotique en temps long d'équations d'ondes dans des domaines extérieurs". Thesis, Université Côte d'Azur (ComUE), 2018. http://www.theses.fr/2018AZUR4067/document.
Pełny tekst źródłaWe are concerned with Schrödinger and wave equations, both linear and non linear, in exterior domains. In particular, we are interested in the so-called Strichartz estimates, which are a family of dispersive estimates measuring decay for the linear flow. They turn out to be particularly useful in order to study the corresponding non linear equations. In non-captive geometries, where all the rays of geometrical optics go to infinity, many results show that Strichartz estimates hold with no loss with respect to the flat case. Moreover, the local smoothing estimates for the Schrödinger equation, respectively the local energy decay for the wave equation, which are another family of dispersive estimates, are known to fail in any captive geometry. In contrast, we show Strichartz estimates without loss in an unstable captive geometry: the exterior of many strictly convex obstacles verifying Ikawa's condition. The second part of this thesis is dedicated to the study of the long time asymptotics of the corresponding non linear equations. We expect that they behave linearly in large times, or scatter, when the domain they live in does not induce too much concentration effect. We show such a result for the non linear critical wave equation in the exterior of a class of obstacles generalizing star-shaped bodies. In the exterior of two strictly convex obstacles, we obtain a rigidity result concerning compact flow solutions, which is a first step toward a general result. Finally, we consider the non linear Schrödinger equation in the free space but with a potential. We prove that solutions scatter for a repulsive potential, and for a sum of two repulsive potentials with strictly convex level surfaces. This provides a scattering result in a framework similar to the exterior of two strictly convex obstacles
Reygner, Julien. "Comportements en temps long et à grande échelle de quelques dynamiques de collision". Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066471/document.
Pełny tekst źródłaThis thesis contains three independent parts, each one of which is dedicated to the study of a particle system, following either a deterministic or a stochastic dynamics, and in which interactions only occur at collisions. Part I contains a numerical and theoretical study of nonequilibrium steady states of the Complete Exchange Model, which was introduced by physicists in order to understand heat transfer in some porous materials. Part II is dedicated to a system of Brownian particles evolving on the real line and interacting through their ranks. The long time and mean-field behaviour of this system is described, then the results are applied to the study of a model of equity market called the mean-field Atlas model. Part III introduces a multitype version of the particle system studied in the previous part, which allows to approximate parabolic systems of nonlinear partial differential equations. The small noise limit of of this system is called multitype sticky particle dynamics and now approximates hyperbolic systems. A detailed study of this dynamics provides stability estimates in Wasserstein distance for the solutions of these systems
Aloui, Faouzia. "Comportement en temps long des solutions de certaines équations d'évolution du second ordre". Paris 6, 2013. http://www.theses.fr/2013PA066002.
Pełny tekst źródłaWe establish in the first chapter an ultimate bound of solutions to a second order linear evolution equation with unbounded damping and bounded forcing term. For estimate the ultimate bound, we use a method of adapted energy functional obtained by perturbing the energy. By using differential inequalities, we obtain an ultimate bound for any solution. The second chapter is devoted to studying the boundedness and compactness of solutions to second order evolution equation with nonlinear damping term and locally integrable forcing term. We construct two energy functionals to prove the properties of boundedness and compactness. The result of compactness is a basic tool to prove the existence of almost periodic solutions and to generalize some results concerning convergence to equilibrium when a nonlinear term is added and the forcing term dies off sufficiently fast for a large time. Chapter 3 is devoted to studying a special case of equation to chapter 2, after establishing the boundedness properties, we give an estimate for an ultimate bound of solutions. The method used is based on distinction of two cases concerning the energy. In the last chapter, we study the asymptotic behavior of solutions of second order nonlinear EDOs near the blow-up. By introducing the polar coordinates and simple calculations, we prove the result
Rhim, Achour. "Prévision du temps de vie du lien pour améliorer la stabilité de routage dans les réseaux Ad hoc". Mémoire, École de technologie supérieure, 2009. http://espace.etsmtl.ca/77/1/RHIM_Achour.pdf.
Pełny tekst źródłaGillot, Pierre. "Stabilité long terme d'un gravimètre atomique et limites de la technique de rejet des effets systématiques". Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066688/document.
Pełny tekst źródłaThis thesis aims at pushing the performances of the atom gravimeter CAG developed at SYRTE. This instrument uses atom interferometry to measure the local gravity acceleration of a free falling 87Rb cold atomic cloud. The improvements of the Raman power control and parameters such as those driving the detection are presented in this thesis. The initial position of the cloud, its mean velocity, its ballistic expansion into the Raman beams and thus their evolution, are important parameters which affect the performances of the CAG. The resulting coupling inhomogeneities modify the symmetry of the sensitivity function of the interferometer and make it sensitive to constant Raman detuning. Moreover, the Raman detuning in a Doppler way cannot be canceled by our rejection technic of systematic effects. The asymmetry of the sensitivity function has been measured and a method is demonstrated to cancel it. Several comparisons between the CAG and different gravimeter types have been performed and their results are developed. The international comparison of absolute gravimeters CCM.G-K2 confirms the CAG accuracy budget. It reveals an Allan standard deviation of 5.710-9g/Hz1/2. In the end, a one month common view measurement with a superconducting gravimeter iGrav is studied. The determination of the iGrav scale factor at the level of 0.1% in a single day and 0.02% in less than a month is obtained with this long measurement. The Allan standard deviation of the gravity residual signal is 610-11g in 12h measurement time
Cilas, Christian. "Stabilité des caractères dans le temps chez les plantes pérennes : étude génétique de la capacité productive chez Coffea spp". Paris 11, 2004. http://www.theses.fr/2004PA112032.
Pełny tekst źródłaWith perennial plants, the efficiency of genetic improvement is limited by particular constraints associated with the economic life span of the crops. Although ways of estimating genetic parameters have been improved, the characters on which analyses are based do not always have a very precise biological sense. For exemple, when considering fruits or seeds, as in the case of coffee trees, how many years of observations does it take to define the "production" character? How can variations in characters over time be integrated with a view to defining a breeding objective in which frequent reference is made to stability and sustainability. After an initial section characterizing competition between fruit production and vegetative growth, two complementary approaches have been taken to try and answer these questions. The first consisted in analysing different trials and mating designs for the species Coffea arabica and Coffea canephora. The particularity of those trials, notably for C. Canephora, lay in the way they were monitored, over a large number of years (14 years). It was found that first cycle production (before coffee trees are cut back for the first time) was not always sufficient for predicting the production of the following cycles. In addition, indexes are proposed for characterizing how planting material distributes its annual yields over time. The second approach consisted in identifying architectural characters able to predict the production capacity of the coffee trees. Thus, the squat coffee trees, with short inter nodes, constitute the morphotypes to be promoted
Altazin, Estelle. "Stabilité et replanification d’un système ferroviaire dense". Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEM008.
Pełny tekst źródłaWhile operating a dense railway system, minor incidents can easily generate delays. Those delays can spread and rapidly amplify along one line, and sometimes to other lines sharing the infrastructure, rolling-stock units or drivers. This thesis addresses the real-time decision-making problem while operating a dense railway system. Dense railway operations are first presented, along with their properties and weaknesses. The notion of stability for a dense railway system is introduced and discussed. Related problems and approaches of the literature are reviewed, both in railway and in urban transportation, and the considered real-time rescheduling problem is presented. A first resolution approach, based on an Integer Linear Programming model, is proposed, and numerical experiments on real data are analyzed. They show the relevance of the rescheduling problem. A more general approach is then proposed, that iterates between an optimization module and a simulation module. All operational actions are considered in the iterative approach, and the use of simulation allows for a precise evaluation of the impact of actions on passengers. This new approach is also multi-objective, thus different solutions can be proposed to the decision makers. A rescheduling tool has been implemented, using the iterative approach, and connected to industrial data flows. Real-life experiments on a Transilien line proved that the tool, and thus the iterative approach, fulfills the decision makers’ expectations and helps reducing the duration of perturbations and their impact on passengers
Cérou, Frédéric. "Filtrage non linéaire sans bruit de dynamique : comportement en temps long et algorithmes numériques". Aix-Marseille 1, 1995. http://www.theses.fr/1995AIX11076.
Pełny tekst źródłaCormier, Quentin. "Comportement en temps long d'un modèle champ moyen de neurones à décharge en interactions". Thesis, Université Côte d'Azur, 2021. http://www.theses.fr/2021COAZ4008.
Pełny tekst źródłaWe study the long time behavior of a McKean-Vlasov stochastic differential equation (SDE), driven by a Poisson measure. In neuroscience, this SDE models the dynamics of the membrane potential of a typical neuron in a large network. The model can be derived by considering a finite network of generalized Integrate-And-Fire neurons and by taking the limit where the number of neurons goes to infinity. Hence the McKean-Vlasov SDE is a mean-field model of spiking neurons.We study existence and uniqueness of the solution this McKean-Vlasov SDE and describe its invariant probability measures. For small enough interaction parameter J, we prove uniqueness and global stability of the invariant measure. For J arbitrary large however, the invariant measures may not be unique. We give a sufficient condition ensuring the local stability of such a given invariant probability measure. Our criterion involves the location of the zeros of an explicit holomorphic function associated to the considered stationary solution. When all the zeros have negative real part, we prove that stability holds. We then give sufficient general conditions ensuring the existence of periodic solutions through a Hopf bifurcation: at some critical interaction parameter J0, the invariant probability losses its stability and periodic solutions appear for J close to J0. To obtain these results, we combine probabilistic and deterministic methods. In particular, a key tool in this analysis is a nonlinear Volterra Integral equation satisfied by the synaptic current.Finally, we illustrate these results with examples which are tractable analytically. Additionally, we give numerical methods to approximate the solution of the mean-field equation and to predict numerically the bifurcations
Lemonnier, Florian. "Étude du comportement en temps long d'équations aux dérivées partielles par des méthodes probabilistes". Thesis, Rennes 1, 2019. http://www.theses.fr/2019REN1S027/document.
Pełny tekst źródłaIn this thesis, we are interested in studying ergodic BSDEs, and our main goal is to apply our results to the large time behaviour of some PDEs. First, we prove some results (already known in the case where the underlying SDE has an additive noise) in the case of an underlying multiplicative noise. Then, we introduce a Poisson process and it leads us to the large time behaviour of a system of coupled PDEs. Finally, when the underlying SDE has a Lévy noise, we make a link with partial integro-differential equations. We also apply these equations to solve some optimal control problems
Michel, Patrice. "Estimation en temps réel des modes souples des voilures de grande dimension". Toulouse, INPT, 2003. http://www.theses.fr/2003INPT059H.
Pełny tekst źródłaIn the aeronautics, the vibrations of an aerofoil can create a critical problem of stability. Aerofoils can even destroy the structure of the plane or simply reduce the quality of the flight. They can also have as a consequence the excitation of badly damped modes which can reduce the performance of laws of orders (based on a rigid model of the plane modifiyng its global dynamics). No long time ago, the rigidity of the aerofoils ensured a frequential decoupling between the structural modes and the piloting modes. Technico-economic constraints lead the aeronautical manufacturers to develop light planes of great scale. Thus, the design of large planes with flexible structure resulted in having these two sets of modes at similar frequencies. In such a context, it becomes difficult to separate the different modes without limiting the maneuvrability of the plane. As a consequence, alternative solutions have be studied. The objective of this thesis is to propose a real time algorithm able to estimate frequencies, amplitudes and possibly the phases of modes with the requirements related to embarked calculation under industrial constraints
Bernuau, Emmanuel. "Robustesse et stabilité des systèmes non-linéaires : un point de vue basé sur l'homogénéité". Phd thesis, Ecole Centrale de Lille, 2013. http://tel.archives-ouvertes.fr/tel-00917798.
Pełny tekst źródłaAriba, Yassine. "Sur la stabilité des systèmes à retards variant dans le temps : théorie et application au contrôle de congestion d'un routeur". Phd thesis, Université Paul Sabatier - Toulouse III, 2009. http://tel.archives-ouvertes.fr/tel-00442454.
Pełny tekst źródłaPetit, Gérard. "Observations VLBI des pulsars millisecondes pour le raccordement des systèmes de référence célestes et la stabilité des échelles de temps". Observatoire de Paris, 1994. https://hal.science/tel-02095454.
Pełny tekst źródłaBouazza, Kheir-Eddine. "Commande basée sur des observateurs pour les systèmes non-linéaires en temps discret". Nancy 1, 2004. http://www.theses.fr/2004NAN10171.
Pełny tekst źródłaResearch activities presented in this thesis concerne the stabilisation, with obserber-based controllers, of discrete-time nonlinear systems. The approach which we proposed doesn't require a particular structure of the output contrary to the methods based on the the passivity theory. Unlike the jurdjevic-quinn method, it doesn't need the stability of the free dynamics. A lyapunov function common to a great number of systems is used for the analysis of stability. Moreover it has the advantage of being simply implementable. Using the results established previously, synthesis of a control law based on an extended kalman observer was given. The third section presents an observer based controller which stabilizes globally exponentially a class of nonlinear systems. An extension to delay systems was established. In the last section, we present a simple conditions in linear matrix inequalities form, which stbilizes asymptotically a large class of delay nonlinear systems. Some other conditions allowing the synthesis of observers for different classes of nonlinear systems were presented
Bernuau, Emmanuel. "Robustesse et stabilité des systèmes non-linéaires : un point de vue basé sur l’homogénéité". Thesis, Ecole centrale de Lille, 2013. http://www.theses.fr/2013ECLI0015/document.
Pełny tekst źródłaThe purpose of this work is the study of stability and robustness properties of nonlinear systems using homogeneity-based methods. Firstly, we recall the usual context of homogeneous systems as well as their main features. The sequel of this work extends the homogenization of nonlinear systems, which was already defined in the framework of weighted homogeneity, to the more general setting of the geometric homogeneity. The main approximation results are extended. Then we develop a theoretical framework for defining homogeneity of discontinuous systems and/or systems given by a differential inclusion. We show that the well-known properties of homogeneous systems persist in this context. This work is continued by a study of the robustness properties of homogeneous or homogenizable systems. We show that under mild assumptions, these systems are input-to-state stable. Finally, the last part of this work consists in the study of the example of the double integrator system. We synthesize a finite-time stabilizing output feedback, which is shown to be robust with respect to perturbations or discretization by using techniques developed before. Simulations conclude the theoretical study of this system and illustrate its behavior
Ben, Rejeb Jihene. "Analyse de stabilité et synchronisation des systèmes singulièrement perturbés". Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0117/document.
Pełny tekst źródłaThis PhD thesis is dedicated to the study of stability and control design for singularly perturbed systems. In the first part, we introduce and analyze a general class of singularly perturbed linear hybrid systems, in which the slow or fast nature of the variables is mode-dependent. Our stability analysis is based on classical results of Lyapunov’s theory for singularly perturbed systems. A second part of this work presents the design of a decentralized control strategy that allows singularly perturbed multi-agent systems to achieve synchronization with global performance guarantees. To avoid the use of centralized information related to the interconnection network structure, the problem is solved by rewriting the synchronization problem in terms of stabilization of a singularly perturbed uncertain linear system