Thèses sur le sujet « Opérateur continu »
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Rousset, Mathias. « Méthodes de "Population Monte-Carlo'' en temps continu est physique numérique ». Toulouse 3, 2006. http://www.theses.fr/2006TOU30251.
Texte intégralIn this dissertation, we focus on stochastic numerical methods of Population Monte-Carlo type, in the continuous time setting. These PMC methods resort to the sequential computation of averages of weighted Markovian paths. The practical implementation rely then on the time evolution of the empirical distribution of a system of N interacting walkers. We prove the long time convergence (towards Schrödinger groundstates) of the variance and bias of this method with the expected 1/N rate. Next, we consider the problem of sequential sampling of a continuous flow of Boltzmann measures. For this purpose, starting with any Markovian dynamics, we associate a second dynamics in reversed time whose law (weighted by a computable Feynman-Kac path average) gives out the original dynamics as well as the target Boltzmann measure. Finally, we generalize the latter problem to the case where the dynamics is caused by evolving rigid constraints on the positions of the process. We compute exactly the associated weights, which resorts to the local curvature of the manifold defined by the constraints
Boumaza, Hakim. « Exposants de Lyapounov et densité d'états intégrée pour des opérateurs de schrödinger continus à valeurs matricielles ». Paris 7, 2007. http://www.theses.fr/2007PA077056.
Texte intégralThis Ph. D thesis deals with dynamical and spectral questions about matrix-valued continuous random Schrödinger operators. Two model: are studied, one is a point interaction model, and the second one is an Anderson-type model. From the dynamical point of view, we prove the separability of the Lyapounov exponents for both models. The methods used here are based upon Lie groups' theory results from Goldsheid and Margulis and from Breuillard and Gelander. This separability of thé Lyapounov exponents leads to the absence of absolutely continuous spectrum for both models. In a second part we study regularity properties of the Lyapounov exponents and of the Integrated Density of States whose existence is proved for matrix-valued continuous models. We prove that these two quantifies are Hölder-continuous, view as functions of the energy parameter. For the Lyapounov exponents, the proof relies on the existence of an invariant measure for the transfer matrices cocycle and on an integral representation of the exponents involving this invariant measure. The Hölder-continuity of the Integrated Density of States is then obtained from the Hölder-continuity of the Lyapounov exponents by using a Thouless formula adapted to matrix-valued continuous operators
Pnevmatikos, Nikolaos. « Contributions à la théorie des jeux : valeur asymptotique des jeux dépendant de la fréquence et décompositions des jeux finis ». Thesis, Paris 1, 2016. http://www.theses.fr/2016PA01E026/document.
Texte intégralThe problems addressed and results obtained in this thesis are divided in two parts. The first part concerns the study of the asymptotic value of frequency-dependent games (FD-games). We introduce a differential game associated to the FD-game whose value leads to a Hamilton-Jacob-Bellman-lsaacs equation. Although an irregularity occurs at the origin, we prove existence of the value in the differential game played over [0.1 ], which allows to prove that the value of the FD-game, as the number of stages tend to infinity, converges to the value of the continuous-time game with initial state 0. ln the second part, the objective is the decomposition of the space of finite games in subspaces of suitable games which admit disguised equilibria and more tractable analysis. This part is divided in two chapters. In the first chapter, we establish a canonical decomposition of an arbitrary game into three components and we characterize the approximate equilibria of a given game in terms of the uniform equilibrium and the equilibrium in dominant strategies that appear in its components. In the second part, we introduce a family of inner products in the space of finite games and we define the class of harmonic games relatively to the chosen inner product. Inspired of the Helmholtz-Hodge decomposition applied to games by Candogan et al (2011 ), we establish an orthogonal decomposition of the space of finite games with respect to the chosen inner product, in the subspaces of potential harmonic and non-strategic games and we further generalize several results of Candogan et al (2011)
Li, Zhe. « Optimisation d'un réseau de distribution de contenus géré par un opérateur réseau ». Télécom Bretagne, 2013. http://www.telecom-bretagne.eu/publications/publication.php?idpublication=13209.
Texte intégralThe exploding HD video streaming traffic calls for deploying content servers deeper inside network operators infrastructures. Telco-CDN are new content distribution services that are managed by Internet Service Providers (ISP). Since the network operator controls both the infrastructure and the content delivery overlay, it is in position to engineer Telco-CDN so that networking resources are optimally utilized. In this thesis, we focus on the optimal resource placement in Telco-CDN. We first investigated the placement of application components in Telco-CDN. Popular services like Facebook or Twitter, with a size in the order of hundreds of Terabytes, cannot be fully replicated on a single data-center. Instead, the idea is to partition the service into smaller components and to locate the components on distinct sites. It is the same and unique method for Telco-CDN operators. We addressed this k-Component Multi-Site Placement Problem from an optimization standpoint. We developed linear programming models, designed approximation and heuristic algorithms to minimize the overall service delivery cost. Thereafter, we extend our works to address the problem of optimal video place- ment for Telco-CDN. We modeled this problem as a k-Product Capacitated Facility Location Problem, which takes into account network conditions and users¿ prefer- ences. We designed a genetic algorithm in order to obtain near-optimal performances of such ¿push¿ approach, then we implemented it on the MapReduce framework in order to deal with very large data sets. The evaluation signifies that our optimal placement keeps align with cooperative LRU caching in term of storage efficiency although its impact on network infrastructure is less severe. We then explore the caching decision problem in the context of Information Cen- tric Network (ICN), which could be a revolutionary design of Telco-CDN. In ICN, routers are endowed with caching capabilities. So far, only a basic Least Recently Used (LRU) policy implemented on every router has been proposed. Our first contri- bution is the proposition of a cooperative caching protocol, which has been designed for the treatment of large video streams with on-demand access. We integrated our new protocol into the main router software (CCNx) and developed a platform that automatically deploys our augmented CCNx implementation on real machines. Ex- periments show that our cooperative caching significantly reduces the inter-domain traffic for an ISP with acceptable overhead. Finally, we aim at better understanding the behavior of caching policies other than LRU. We built an analytical model that approximates the performance of a set of policies ranging from LRU to Least Frequently Used (LFU) in any type of network topologies. We also designed a multi-policy in-network caching, where every router implements its own caching policy according to its location in the network. Compared to the single LRU policy, the multi-caching strategy considerably increases the hit- ratio of the in-network caching system in the context of Video-on-Demand application. All in one, this thesis explores different aspects related to the resource placement in Telco-CDN. The aim is to explore optimal and near-optimal performances of various approaches
Martin, Alexandre. « Théorie de Mourre et opérateurs de Schrödinger : De nouvelles classes d'opérateurs conjugués ». Thesis, Cergy-Pontoise, 2018. http://www.theses.fr/2018CERG0978/document.
Texte intégralIn this thesis, we are interested in the study of the essential spectrum of Schrödinger operators and more particulary in the obtention of a Limiting Absorption Principle for these operators. This Limiting Absorption Principle consists on the existence of a limit for the resolvent operator when the spectral parameter is near the essential spectrum and permits to know some properties about the group generated by the Schrödinger Hamiltonian we study. A technique to prove this Limiting Absorption Principle is to use the Mourre theory. This theory needs to use an other operator called the conjugate operator. When we want to apply the Mourre theory to Schrödinger operators, we usually used a conjugate operatornamed the generator of dilations. This operator implies some conditions of decay on the derivatives of the potentials which can be a problem in certain cases. In this thesis, we will apply the Mourre theory with other types of conjugate operators wich, for some of them, does not imply any conditions on the derivatives of the potential.In a first part, we will be interested in Schrödinger operators on the euclidian space. We will show a Limiting Absorption Principle at positive energy, a Limiting Absorption principle at zero energy and the absence of eigenvalue embedded in the essential spectrum. In a second part, we will be interested in Schrödinger operators on wave guides for which we will prove a Limiting Absorption Principle far thresholds and near thresholds
Tang, Xiaoming. « Contribution à la conception des systèmes à base de connaissances temps réel pour l'aide au contrôle de procédés continus ». Valenciennes, 1989. https://ged.uphf.fr/nuxeo/site/esupversions/14214bfb-9aa9-4aef-b529-a5014cdbc3f6.
Texte intégralNtumba, wa Ntumba Patient. « Ordonnancement d'opérateurs continus pour l'analyse de flux de données à la périphérie de l'Internet des Objets ». Electronic Thesis or Diss., Sorbonne université, 2022. http://www.theses.fr/2022SORUS183.
Texte intégralData stream processing and analytics (DSPA) applications are widely used to process the ever increasing amounts of data streams produced by highly geographically distributed data sources, such as fixed and mobile IoT devices, in order to extract valuable information in a timely manner for actuation. DSPA applications are typically deployed in the Cloud to benefit from practically unlimited computational resources on demand. However, such centralized and distant computing solutions may suffer from limited network bandwidth and high network delay. Additionally, data propagation to the Cloud may compromise the privacy of sensitive data. To effectively handle this volume of data streams, the emerging Edge/Fog computing paradigm is used as the middle-tier between the Cloud and the IoT devices to process data streams closer to their sources and to reduce the network resource usage and network delay to reach the Cloud. However, Edge/Fog computing comes with limited computational resource capacities and requires deciding which part of the DSPA application should be performed in the Edge/Fog layers while satisfying the application response time constraint for timely actuation. Furthermore, the computational and network resources across the Edge-Fog-Cloud architecture can be shareable among multiple DSPA (and other) applications, which calls for efficient resource usage. In this PhD research, we propose a new model for assessing the usage cost of resources across the Edge-Fog-Cloud architecture. Our model addresses both computational and network resources and enables dealing with the trade-offs that are inherent to their joint usage. It precisely characterizes the usage cost of resources by distinguishing between abundant and constrained resources as well as by considering their dynamic availability, hence covering both resources dedicated to a single DSPA application and shareable resources. We complement our system modeling with a response time model for DSPA applications that takes into account their windowing characteristics. Leveraging these models, we formulate the problem of scheduling streaming operators over a hierarchical Edge-Fog-Cloud resource architecture. Our target problem presents two distinctive features. First, it aims at jointly optimizing the resource usage cost for computational and network resources, while few existing approaches have taken computational resources into account in their optimization goals. More precisely, our aim is to schedule a DSPA application in a way that it uses available resources in the most efficient manner. This enables saving valuable resources for other DSPA (and non DSPA) applications that share the same resource architecture. Second, it is subject to a response time constraint, while few works have dealt with such a constraint; most approaches for scheduling time-critical (DSPA) applications include the response time in their optimization goals. To solve our formulated problem, we introduce several heuristic algorithms that deal with different versions of the problem: static resource-aware scheduling that each time calculates a new system deployment from the outset, time-aware and resource-aware scheduling, dynamic scheduling that takes into account the current deployment. Finally, we extensively and comparatively evaluate our algorithms with realistic simulations against several baselines that either we introduce or that originate / are inspired from the existing literature. Our results demonstrate that our solutions advance the current state of the art in scheduling DSPA applications
Rodríguez, Porras Cristóbal. « Une analyse ensembliste des opérateurs sur l'espace de Banach l_infty/c-0 ». Sorbonne Paris Cité, 2015. http://www.theses.fr/2015USPCC258.
Texte intégralWe investigate linear bounded operators on X=l_infty/c_O and related spaces. We begin by studying operators T:X→X focusing on the possibility of representing their fragments of the form T_{B,A}:l_infty(A)/c_0(A)→, l_infty(B)/c_0(B) for A,BCN infinite by means of operators from Linfty(A) into l_infty(B), infinite AxB-matrices, continuous maps from B^*=βB\B into A^*, or bijections from B to A. We present many examples, introduce and investigate several classes of operators; for some we obtain satisfactory representations and for others we show that it is impossible. We show that there are automorphisms of X which cannot be lifted to operators on l_infty and assuming OCA+MA we show that every automorphism of X with no fountains or with no funnels is locally, i. E. , for some infinite A,B C̱N as above, induced by a bijection from B to A. This additional set-theoretic assumption is necessary as we show that the Continuum Hypothesis implies the existence of counterexamples of diverse flavours. Later, we look into isomorphic embeddings of the l_infty-sum of X into X. We show that under PFA the localstructure of the induced coordinate operators has great influence over the original operator. As an application, we show the impossibility under PFA of embedding Linfty(X) into X by means of some well-known classes of operators, contrasting with Drewnowski and Roberts' construction under CH of such an embedding as a composition operator. Finally, we present a modem proof of a slightly improved version of a result by Kadec and Pelczyński on sequences of Radon measures. We show an application of this resuit to operators from X into itself
Boumaza, Hakim. « Exposants de Lyapounov et Densité d'Etats Intégrée pour des opérateurs de Schrödinger continus à valeurs matricielles ». Phd thesis, Université Paris-Diderot - Paris VII, 2007. http://tel.archives-ouvertes.fr/tel-00264341.
Texte intégralGarcia, Arroyo Mauricio. « Étude variationnelle des états électroniques de la molécule de polyacétylène : modèles continu et discret ». Paris 9, 2011. https://basepub.dauphine.fr/handle/123456789/8010.
Texte intégralThis thesis is devoted to the study of the relativistic model of the molecule of polyacetylene in its discrete version and continuous approximation. We apply some techniques introduced by Kennedy and Lieb, and by Hainzl, Lewin, Séré and Solovej to solve similar type problems in QED. In the first part, we study the continuous model of polyacetylene. To deal with the fact that the Dirac operator is not bounded from below, we define a periodic model on an interval of size L > 0 and we introduce an ultraviolet cut-off in Fourier space. We prove the existence and uniqueness of fundamental states of this periodic system and we show that the minimizers are translation-invariant. Then we study the thermodynamic limit when the period L goes to infinity and we define the fundamental states in the general case as well as the energy per length unit. The second part is devoted to the study of the discrete model introduced by Su, Schrieffer and Heeger. We also define a periodic problem to obtain a Hamiltonian bounded from below. We present a different proof from that given by Kennedy and Lieb of the fact that the dimerized configuration of the molecule minimizes the energy. Our approach is constructive and produces explicit formulas for the global minimizers and the fundamental energy. Finally, we prove the existence of kink type equilibrium states of an infinite molecule
Taborin, Vincent. « Coopération entre opérateur et système d'aide à la décision pour la conduite de procédés continus : Application à l'interface operateur système expert du projet alliance ». Valenciennes, 1989. https://ged.uphf.fr/nuxeo/site/esupversions/6fb5d6d3-5a45-422f-9ce9-60f095872288.
Texte intégralAllonsius, Damien. « Etude spectrale d'opérateurs de Sturm-Liouville et applications à la contrôlabilité de problèmes paraboliques discrets et continus ». Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0369/document.
Texte intégralIn this thesis, we study the null controllability of some continous and semi discretized parabolic systems. We first consider cascade systems of parabolic equations of the form ∂t −(∂xγ∂x +q). The space variable belongs to a real and bounded interval and this system is semi-discretized in space by a finite differences scheme. Applying the so called moments method, we prove null controllability and φ(h) null controllability results, depending on the hypotheses on the mesh and on functions γ and q. Then, we extend this results when the space variable belongs to a cylindrical domain which control zone is in a section at the border of the cylinder. This cylindrical domain is decomposed into a product of two spaces. On the first, of dimension 1, we apply the results described previously. On the second, we use the Lebeau-Robbiano's procedure. In this framework, we prove φ(h) null controllability results on the discretized domain as well as null controllability results on the continous problem. In another section, we investigate the computation of minimal time of null controllability of Grushin's equation defined on a rectangular domain which control region is a vertical strip. This problem of control amounts to study a countably infinite family, indexed by the Fourier parameter $n$, of null control problems of parabolic equations, tackled, once again, with the moments method
Daireaux, Benoît. « Analyse des algorithmes d'Euclide : une approche dynamique ». Caen, 2005. http://www.theses.fr/2005CAEN2009.
Texte intégralDaireaux, Benoit. « Analyse des algorithmes d'Euclide : une approche dynanique ». Phd thesis, Université de Caen, 2005. http://tel.archives-ouvertes.fr/tel-00258776.
Texte intégralBourdon, Jérémie. « Analyse dynamique d'algorithmes : exemples en arithmétique et en théorie de l'information ». Caen, 2002. http://www.theses.fr/2002CAEN2062.
Texte intégralRotondo, Pablo. « Probabilistic studies in number theory and word combinatorics : instances of dynamical analysis ». Thesis, Sorbonne Paris Cité, 2018. http://www.theses.fr/2018USPCC213/document.
Texte intégralDynamical Analysis incorporates tools from dynamical systems, namely theTransfer Operator, into the framework of Analytic Combinatorics, permitting the analysis of numerous algorithms and objects naturally associated with an underlying dynamical system.This dissertation presents, in the integrated framework of Dynamical Analysis, the probabilistic analysis of seemingly distinct problems in a unified way: the probabilistic study of the recurrence function of Sturmian words, and the probabilistic study of the Continued Logarithm algorithm.Sturmian words are a fundamental family of words in Word Combinatorics. They are in a precise sense the simplest infinite words that are not eventually periodic. Sturmian words have been well studied over the years, notably by Morse and Hedlund (1940) who demonstrated that they present a notable number theoretical characterization as discrete codings of lines with irrationalslope, relating them naturally to dynamical systems, in particular the Euclidean dynamical system. These words have never been studied from a probabilistic perspective. Here, we quantify the recurrence properties of a ``random'' Sturmian word, which are dictated by the so-called ``recurrence function''; we perform a complete asymptotic probabilistic study of this function, quantifying its mean and describing its distribution under two different probabilistic models, which present different virtues: one is a naturaly choice from an algorithmic point of view (but is innovative from the point of view of dynamical analysis), while the other allows a natural quantification of the worst-case growth of the recurrence function. We discuss the relation between these two distinct models and their respective techniques, explaining also how the two seemingly different techniques employed could be linked through the use of the Mellin transform. In this dissertation we also discuss our ongoing work regarding two special families of Sturmian words: those associated with a quadratic irrational slope, and those with a rational slope (not properly Sturmian). Our work seems to show the possibility of a unified study.The Continued Logarithm Algorithm, introduced by Gosper in Hakmem (1978) as a mutation of classical continued fractions, computes the greatest common divisor of two natural numbers by performing division-like steps involving only binary shifts and substractions. Its worst-case performance was studied recently by Shallit (2016), who showed a precise upper-bound for the number of steps and gave a family of inputs attaining this bound. In this dissertation we employ dynamical analysis to study the average running time of the algorithm, giving precise mathematical constants for the asymptotics, as well as other parameters of interest. The underlying dynamical system is akin to the Euclidean one, and was first studied by Chan (around 2005) from an ergodic, but the presence of powers of 2 in the quotients ingrains into the central parameters a dyadic flavour that cannot be grasped solely by studying this system. We thus introduce a dyadic component and deal with a two-component system. With this new mixed system at hand, we then provide a complete average-case analysis of the algorithm by Dynamical Analysis
Bonnot, Justine. « Error Analysis for Approximate Computing Systems ». Thesis, Rennes, INSA, 2019. https://partages.insa-rennes.fr/alfresco/s/api/node/content/workspace/SpacesStore/4b8b3149-5fc4-439b-abc5-ef663a070daf/2019ISAR0008_BONNOT_Justine.pdf?a=true.
Texte intégralApproximate Computing is an energy- aware computing technique that relies on the exploitation of the tolerance to imprecision of an application. Developed to face the end of Moore’s law, it answers the growing demand in computing capacity. Approximation techniques have been proposed at different abstraction levels, from circuit to system level. This thesis focuses on the development of methods and tools to quickly evaluate the impact of different Approximate Computing techniques on the application quality metric. The study of the induced errors is critical to use approximations in the industry. Approximate Computing techniques have been considered at two different levels, the hardware level with the study of inexact arithmetic operators and the data level with the study of fixed-point arithmetic. First, efficient simulation-based characterization methods have been proposed to derive statistics on the errors induced by the considered approximation. Inferential statistics have been proposed to reduce the time for error characterization. The proposed characterization methods are based on adaptive simulations and statistically characterizes the approximation error according to user-defined confidence requirements. Then, the obtained error metrics are linked with the application quality metric. For inexact operators, a simulator has been proposed for the approximation design space exploration process to select the best approximation for the considered application. For fixed-point arithmetic, the proposed error model has been implemented in a fixed-point refinement algorithm to determine the optimized word-lengths of the internal variables in an application. The results of this thesis are proposing concrete methods to ease the implementation of Approximate Computing in industrial applications, speeding up state-of-the-art methods from one to three orders of magnitude
Vera, Antonio. « Analyses de l'algorithme de Gauss : applications à l'analyse de l'algorithme LLL ». Phd thesis, Université de Caen, 2009. http://tel.archives-ouvertes.fr/tel-01073359.
Texte intégralBolte, Jérôme. « Sur des systèmes dynamiques dissipatifs de type gradient : applications en optimisation ». Phd thesis, Université Montpellier II - Sciences et Techniques du Languedoc, 2003. http://tel.archives-ouvertes.fr/tel-00002568.
Texte intégralde type gradient sont l'objet central de cette thèse. Le
caractère dissipatif de telles dynamiques est au coeur de
nombreux domaines en mathématiques : optimisation,
mécanique, équations d'évolutions en dimension infinie.
Dans une première partie, les champs de gradients (ou de sous-différentiels
de fonction convexe) sont contrôlés à l'aide d'opérateurs-barrières.
La motivation essentielle est d'obtenir
des méthodes intérieures de descente en vue d'optimiser
une fonction sous des contraintes convexes. Le cadre
d'étude proposé permet d'unifier dans un même formalisme de nombreuses
méthodes continues : gradient projeté, plus grande pente riemannienne,
méthode continue de Newton... Parmi les conséquences de
la généralisation proposée, on peut, par exemple, évoquer des
résultats abstraits de viabilité et de convergence globale. Toujours
dans cette
perspective, les fonctions de Legendre jouent un rôle crucial~:
elles permettent d'une part de donner lieu à des structures
riemanniennes possédant de nombreuses propriétés - parmi lesquelles une
propriété d'intégration caractéristique remarquable -, et d'autre part,
elles fournissent en dimension infinie un cadre intéressant
pour l'étude de certaines équations d'évolution de type
parabolique.
La deuxième partie est consacrée à l'étude de systèmes
dynamiques du second ordre en temps avec une dissipation géométrique
de type hessien. Outre leur intérêt en optimisation
et leurs liens avec les méthodes de type Newton, ces systèmes
sont d'une grande souplesse et permettent d'approcher certains
phénomènes non-lisses en mécanique unilatérale. En guise d'application,
il est en effet prouvé que les systèmes considérés permettent
d'obtenir à la limite des dynamiques
satisfaisant des lois de chocs inélastiques. Les
perspectives de cette étude ouvrent en particulier la voie à une approche
alternative de certains systèmes d'inégalités variationnelles de type
hyperbolique.
L'une des préoccupations majeures de cette thèse est la question
de la convergence des orbites des systèmes étudiés. Dans le
cadre de la minimisation convexe, quasi-convexe, ou analytique, de nombreux
résultats sont proposés : convergence globale, ,
vitesse de convergence, contrôle asymptotique, attractivité des
minima sous contraintes en dimension infinie.