Dissertations / Theses on the topic 'Modèles de fermions sur réseau'
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Linnér, Erik. "Interplay of collective fluctuations in strongly correlated fermionic systems." Electronic Thesis or Diss., Institut polytechnique de Paris, 2023. http://www.theses.fr/2023IPPAX090.
Full textStrongly correlated systems often display rich phase diagrams exhibiting different ordered phases involving spin, charge, pairing, or orbital degrees of freedom. The theoretical description of the competition between different instabilities in strongly correlated systems giving rise to this phenomenology, remains one of the holy grails of modern condensed matter theory. It poses a tremendous challenge of both conceptual and computational complexity, and thus the interplay of competing electronic fluctuations constitutes a roadblock to the understanding of the complex phase diagrams of a wide range of correlated quantum materials. This motivates the search for constructing simplified methods to study interplaying collective fluctuations.We introduce a multichannel extension of the recently developed fluctuating field approach to competing collective fluctuations in correlated electron systems. The method is based on a variational optimization of a trial action that explicitly contains the order parameters of the leading fluctuation channels. It gives direct access to the free energy of the system, facilitating the distinction between stable and metastable phases of the system.We apply our approach to the extended Hubbard model, a paradigmatic fermionic lattice model, occupying a prime place in condensed matter theory due to the potential relevance of its repulsive and attractive versions for both electronic materials and artificial systems.Utilising the technique to study the weak to intermediate coupling regime of the repulsive interaction, we find it to capture the interplay of competing charge density wave and antiferromagnetic fluctuations with qualitative agreement with more computationally expensive methods. In addition, the method allows access to excited-state properties, through the one-particle excitation spectrum, and many-body correlation effects, through the self-energy, directly on the real-frequency axis without using numerical analytic continuation techniques. The multichannel fluctuating field approach thus offers a promising route for a numerically low-cost treatment of the interplay between collective fluctuations in small to large systems.Using the introduced multichannel fluctuating field approach, we explore the phase diagram of the extended Hubbard model in both repulsive and attractive regimes, addressing the interplay of fluctuations in the antiferromagnetic, charge density wave, s-wave superconducting, and phase separation channels. Despite the fact that this model has been intensively studied for decades, our novel approach allows us to identify a novel phase that is characterised by the coexistence of collective s-wave superconducting and phase separation fluctuations. These findings resonate with previous observations of interplaying phase separation and superconducting phases in electronic systems, most importantly in high-temperature superconductors. In addition, the multichannel fluctuating field method allows to display the quintessential nature of the extended Hubbard model through the large variety of types of competitions which emerges from the interplaying instabilities. The general nature of the proposed theory, allowing to incorporate a variety of collective modes, makes it a promising tool for studying the interplay of collective fluctuations in strongly correlated fermionic systems
Ruiz, Jean. "Contribution à l'étude des transitions de phases de modèles sur réseau : modèles à symétrie continue et modèles de Potts." Aix-Marseille 2, 1987. http://www.theses.fr/1987AIX22020.
Full textHarraud, Pierre-Antoine. "Etude de la structure du nucléon par des calculs de QCD sur réseau avec des fermions de masse twistée." Phd thesis, Grenoble, 2010. http://tel.archives-ouvertes.fr/tel-00546526.
Full textHarraud, Pierre-Antoine. "Étude de la structure du nucléon par des calculs de QCD sur réseau avec des fermions de masse twistée." Grenoble, 2010. http://www.theses.fr/2010GRENY057.
Full textUnderstanding the structure of the nucleon from Quantum ChromoDynamics is one of the greatest challenges of hadronic physics. Only lattice QCD allows to determine numerically the values of the observables from ab-initio principles. This thesis aims to study the nucleon form factors and the first moments of partons distribution fnctions by using a discretized action with twisted mass fermions. As a main advantage, the discretization effects are suppressed at first order in the lattice spacing. In addition, the set of simulations allows a good control of the systematical errors. After reviewing the computation technics, the results obtained for a wide range of parameters are presented, with lattice spacings varying from 0. 0056 fm to 0. 089 fm, spatial volumes from 2. 1 up to 2. 7 fm and several pion masses in the range of 260-470 MeV. The vector renormalization constant was determined in the nucleon sector with improved precision. Concerning the electric charge radius, we found a finite volume effect that provides a key towards an explanation of the chiral dependence to the physical point. The results for the magnetic moment, the axila charge, the magnetic and axial charge radii, the momentum and spin fractions carried by the quarks show no dependence on the lattice spacing nor volume. In our range of pion masses, their values show a deviationfrom the experimental values. Their chiral behaviour do not exhibit the curvature predicted by the chiral perturbation theory which could explain the apparent discrepancy
Vignaud, Yvon. "Interfaces rigides des modèles sur réseau : une application de la positivité par réflexion." Phd thesis, Université de la Méditerranée - Aix-Marseille II, 2007. http://tel.archives-ouvertes.fr/tel-00265658.
Full textPour chacun de ces modèles, nous imposons des conditions au bord spécifiques qui assurent l'existence d'une interface ; les mesures de Gibbs associées à de telles conditions au bord satisfont alors de puissantes inégalités de corrélation. Ces inégalités nous permettent de montrer que les interfaces considérées sont rigides, au sens où ce sont des hyperplans légèrement déformés par des aspérités locales. Cette méthode est une version restreinte de la méthode de positivité par réflexion, l'une des directions de réflexion étant prohibée par les conditions au bord choisies.
Pour Ising et Potts, notre méthode simplifie considérablement les démonstrations historiques, puisque ni la théorie de Pirogov-Sinai, ni les développements en amas ne sont nécessaires à son application. Par ailleurs, la théorie-PS n'est directement envisageable ni pour le modèle continu ni son approximation car leurs états fondamentaux sont infiniment dégénérés; notre méthode est donc une réelle alternative à ces techniques.
Tekitek, Mohamed Mahdi. "Identification de modèles et de paramètres pour la méthode de Boltzmann sur réseau." Phd thesis, Université Paris Sud - Paris XI, 2007. http://tel.archives-ouvertes.fr/tel-00207541.
Full textLa première partie introduit et analyse la méthode.
La deuxième partie décrit une approche variationnelle pour l'assimilation de paramètres relatifs à la méthode du gaz de Boltzmann sur réseau. Une méthode adjointe discrète en temps est développée. L'algorithme est d'abord testé sur un écoulement de type Poiseuille linéaire (problème de Stokes), puis il est appliqué à un problème non linéaire. Des résultats encourageants sont obtenus pour un et deux paramètres inconnus.
Finalement la troisième partie décrit une adaptation des couches absorbantes de Bérenger. Il en résulte un modèle d'automate de Boltzmann à neuf vitesses discrètes. Une analyse des ondes réfléchies est ensuite réalisée entre deux milieux de Boltzmann à une dimension, ce qui permet d'obtenir un équivalent des formules de Fresnel pour les schémas de Boltzmann et de proposer des modifications du schéma à l'interface pour annuler les ondes réfléchies. En deux dimensions, la même analyse d'ondes réfléchies met en évidence l'apparition de modes de Knudsen et des ondes transverses qui rendent l'analyse complexe.
Vignaud, Yvon [Charlie]. "Interfaces rigides des modèles sur réseau : une application de la positivité par réflexion." Aix-Marseille 2, 2007. http://theses.univ-amu.fr.lama.univ-amu.fr/2007AIX22019.pdf.
Full textWe study interfaces for four spin models on the lattice Zd, d ≥ 3: the Ising model at low temperature, the Potts model at critical point, a continuous symmetry model and its associated clock approximation. Interfaces of the last two models were not previously dealt with. For each model, we use specific boundary conditions that force the existence of an interface; related Gibbs measures then satisfy the so-called chessboard estimates, which are powerful correlation inequalities. These estimates are a simple way of showing that such interfaces are rigid, in the sense that they deviate only locally from a perfect hyperplane. This method is a restricted version of the so-called reflection positivity method, since reflections in certain directions are forbidden by the chosen boundary conditions. In the case of Ising and Potts models, our method drastically simplifies historical proofs respectively devised by Dobrushin and Messager et al. , since its requires neither Pirogov-Sina˘ı theory nor cluster expansions. Besides, PS-theory is not directly available for the continuous model and its clock approximation, their ground states being infinitely degenerated; our method is thus a true alternative to such techniques
Tekitek, Mohamed-Mahdi. "Identification de modèles et de paramètres pour la méthode de Boltzmann sur réseau." Paris 11, 2007. https://tel.archives-ouvertes.fr/tel-00207541.
Full textThis thesis is composed of three parts. Firstly a study of Lattice Boltzmann scheme (LBE) is performed. Then Adjoint Lattice Boltzmann scheme (ALBE) is introduced for parameters identification. Finally a new Lattice Boltzmann scheme (BRB) is proposed to modelise B\'erenger's Perfectly Matched Layer (PML) method. The first part introduces and analyzes the LBE method. The second part describes a variational approach for parameters identification adapted to LBE. A time discrete adjoint method is developed. At first the ALBE method is applied to Stokes' problem and then to a nonlinear problem. Good results have been obtained in the cases of one or tow unknown parameters. Finally the third part describes an adaptation of PML for LBE. The LB scheme is obtained with 9 discretes velocities. An analysis of reflected waves between two one dimensional LB media is performed. It provides us an equivalent for the Fresnel formula for LBE interface. That gives us same ideas to modify the LB scheme at the interface to vanish reflected waves. In the two dimensional case, the same analysis of reflected waves shows the existence of Knudsen modes and transverse waves, which make the analysis more difficult
Marcou, Olivier. "Modélisation et contrôle d’écoulements à surface libre par la méthode de Boltzmann sur réseau." Perpignan, 2010. http://www.theses.fr/2010PERP1001.
Full textThis 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
Selva, Franck. "Formation d'une molécule de Wigner sur un réseau bidimensionnel : structure et aimantation." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2002. http://tel.archives-ouvertes.fr/tel-00001528.
Full textGallois, Passat Isabelle. "Analyse de modèles d'évolution sur un réseau, cas d'un système épidémique avec diffusion non locale." Thesis, Cergy-Pontoise, 2015. http://www.theses.fr/2015CERG0786.
Full textThis thesis is devoted to the mathematic analysis of time-dependent models on complex networks. There are three chapters. The first two chapters concern a model for the spread of epidemics on networks while the third chapter concerns Price equation, which arises as a model for the growth of complex networks.Most part of this thesis is concentrated in the first two chapters, in which we propose and analyze a SIS-type epidemic model with nonlocal diffusion. This model is derived from a discrete model, by considering here the degree as a continuous variable taking nonnegative values. Hence the network is described by the degree distribution of its nodes, where the epidemic transmission takes place. Migration occurs along the edges of the network and corresponds to nonlocal diffusion. The evolution system for the density of susceptible and infected individuals reads as a coupled system of nonlinear equations with nonlocal terms, which are given by the mean values of these densities on the network. We provide the analysis of this time-dependent system, distinguishing the cases of limited transmision (chapter 1) and illimited transmission (chapter 2).We first rigorously prove the existence of a unique solution to the system, either locally or globally in time, using a fixed point method. Next we establish necessary and sufficient threshold conditions for the existence of an endemic equilibrium. We then investigate the linear stability of both the disease-free and the endemic equilibrium and compare our results to the ones obtained for the discrete system. In the case of equal diffusivities and illimited transmission, we reduce the system to a Fisher-type equation with nonlocal diffusion, for which we prove a comparison principle. This allows us to study the large-time asymptotics of the solution for arbitrary initial data.The last chapter deals with Price equation, which is a model for the growth of networks. The model reads as a discrete recursive equation that provides the time-evolution of the probability distribution of the degrees in a growing network. We show rigorously that the solution converges to a stationary state exhibiting a power-law tail, whose exponent is explicitly given
Amoretti, René. "Modélisation et commande optimale d'un réseau de distribution d'eau potable : mise en oeuvre, test et étude des performances sur le réseau de Fium'Orbo." Aix-Marseille 3, 1990. http://www.theses.fr/1990AIX30001.
Full textBaron, Rémi. "Chromodynamique quantique sur réseau et propriétés du nucléon." Phd thesis, Université Paris Sud - Paris XI, 2009. http://tel.archives-ouvertes.fr/tel-00439372.
Full textBouhali, Omar. "Contribution des convertisseurs multiniveaux au raccordement de la production d'origine éolienne sur un réseau électrique." Ecole Centrale de Lille, 2007. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/2007/50376-2007-Bouhali.pdf.
Full textThis work deals with the evaluation of the possibilities which offers the multilevel converters for the connection of a wind generation system including a storage system. First of all, modeling and control of the connection are given. Classically, the grid converter is controlled to regulate the intermediate continuous bus. The use of a NPC converter topology requires the balancing of the DC-bus voltage. A solution based on the redundant configurations is proposed. Then, the modeling and the control of a three-phase multilevel inverter are presented by extending the presented concepts, which are established by using the vectorial mathematical tools. The storage unit is used to control the continuous bus and consequently compensate the fluctuations of the wind power. The energy supervision of the association of both sources is presented and the operation range is given. Various possibilities of the connection of both sources are proposed and evaluated. Experimental validations are given. Finally, the use of a converter using four series capacitors in the DC-bus is developed for the multi source system connections. Various possibilities of connection on this continuous bus are investigated. The supervision system of the powers for each case is also given
Choungmo, Fofack Nicaise Éric. "Sur des modèles pour l'évaluation de performance des caches dans un réseau cœur et de la consommation d'énergie dans un réseau d'accès sans-fil." Phd thesis, Université Nice Sophia Antipolis, 2014. http://tel.archives-ouvertes.fr/tel-00968894.
Full textChoungmo, Fofack Nicaise Éric. "Sur des modèles pour l’évaluation de performance des caches dans un réseau cœur et de la consommation d’énergie dans un réseau d’accès sans-fil." Thesis, Nice, 2014. http://www.theses.fr/2014NICE4006/document.
Full textInternet is a real ecosystem. It grows, evolves and adapts to the needs of users in terms of communication, connectivity and ubiquity of users. In the last decade, the communication paradigm has shifted from traditional host-to-host interactions to the recent host-to-content model; while various wireless and networking technologies (such as 3/4G smartphones and networks, online media streaming, social networks, clouds, Big-Data, information-centric networks) emerged to enhance content distribution. This development shed light on scalability and energy efficiency issues which can be formulated as follows. How can we design or optimize such large scale distributed systems in order to achieve and maintain high-speed access to contents while (i) reducing congestion and energy consumption in the network and (ii) adapting to the temporal locality of users demand in a continuous connectivity paradigm? In this thesis we focus on two solutions proposed to answer this question: In-network caching and Power save protocols for scalability and energy efficiency issues respectively. Precisely, we propose analytic models for designing core cache networks and modeling energy consumption in wireless access networks. Our studies show that the prediction of the performance of general core cache networks in real application cases can be done with absolute relative errors of order of 1%–5%; meanwhile, dramatic energy save can be achieved by mobile devices and base stations, e.g., as much as 70%–90% of the energy cost in cells with realistic traffic load and the considered parameter settings
Blondeau-Fournier, Olivier. "Approche combinatoire des modèles minimaux en théorie des champs conformes : connexion avec les chemins sur réseau demi-entier." Thesis, Université Laval, 2010. http://www.theses.ulaval.ca/2010/27705/27705.pdf.
Full textGobron, Thierry. "Modèles de gaz sur réseau appropriés à l'étude de systèmes de particules en régime de saut sous-amorti." Paris 11, 1986. http://www.theses.fr/1986PA112040.
Full textThis thesis set out a lattice gas model which describes the transport properties of classical particle systems in the underdamped hopping régime (superionic conductors, diffusion of adsorbed particles. . . ) in a simple way. On each site, the state of a particle is described by a multicomponent vector [P(x,t)˃ each possible kinetic state for the particle being associated with one of the components. A master equation. That describes the evolution of probability distribution in an independent particle model is established. Although the operator m describes the evolution of the system on a long time scale, it is constructed by determining its matrix elements as the jump probabilities for the particle between times t- τ and t+ τ, τ being a microscopic time scale. Lt is shown that this operator can be factorised into a shifting operator G, diagonal, and a state transition operator Mσ. From the master equation and with the help of the symmetry group that leaves M invariant, several physical quantities such as the diffusion constant, the A. C. Conductivity and the structure factor are explicitly calculated for several lattices in 1 ,2 and 3 dimensions. Even though the model does not allow for a detailled balance, fluctuation and dissipation can be related with a Kubo formula. The influence of a magnetic field and external constraints applied to the system is examinated. Finally, a Boltzmann equation is established and compared to the one that have been proposed in an empirical approach by Rice and Roth
Bouaouiche, Toufik. "Commande à structure variable et étude de l'intégration d'éolienne à base de machine asynchrone à double alimentation sur le réseau électrique." Nantes, 2007. http://www.theses.fr/2007NANT2041.
Full textThis thesis deals with a 7. 5 kW variable wind speed turbine with doubly-fed induction generator (DFIG). The goal is to design a robust control for the DFIG and minimise the impact of grid faults, unbalanced voltages or current harmonics on the performances of the system. After a brief historic of the evolution of wind turbines, the state of the art of used generators and their associated power electronics is presented. For mechanical part, a variable blade pitch wind turbine is used for maximal power extraction. The second part depicts the model of variable speed constant frequency DFIG using back-to-back PWM voltage source converters and the corresponding control schemes. The feasibility and advantages of soft synchronizing DFIG to the grid using stator voltage control method is discussed. The rotor side converter is used to control the wind turbine output power in order to follow a predefined power-speed tracking characteristics (MPPT) and the voltage (or reactive power) at the grid terminals. Both linear or non-linear control structures based respectively on PI regulator or variable structure control (sliding mode) are developed and compared. Some experimental results are shown to validate simulation study. The last part of this work is devoted to the integration of the wind turbine based on DFIG to the distribution network. In particular the behavior of the system under unbalanced power transmission grids, current harmonics or short circuit faults conditions is studied. A new active control strategy based on sliding mode regulators is developed to compensate electrical perturbations, improve power quality and assure the possibility of stabilizing and continuous mode function
Bourgougnon, Nathalie. "Modélisation au moyen des Réseaux de Petri Temporisés Stochastiques d'une application de contrôle-commande de poste de transformation d'énergie électrique répartie sur le réseau de terrain FIP." Toulouse 3, 1996. http://www.theses.fr/1996TOU30132.
Full textAbdallah, Maher. "Sur les méthodes de discrétisation numérique de problèmes hyperboliques non linéaires appliquées aux équations de Barré de Saint-Venant pour la modélisation de l'hydraulique en réseau d'assainissement." Université Louis Pasteur (Strasbourg) (1971-2008), 2005. https://publication-theses.unistra.fr/public/theses_doctorat/2005/ABDALLAH_Maher_2005.pdf.
Full textThe dysfunctions of the sanitation networks and of the natural environments such as river, particularly in rainy weather, are frequent in certain agglomerations and can lead to serious problems for local communities. Pollution of the receiving environment can sustain major damage for the population, thus the improvement of the quality of the receiving natural environments of urban pollution is a paramount need and passes by a control of the flow of pollution discharged from overflows and to control their hydraulic behavior. In this context, the research unit of "urban hydraulic system" of the national school of waters and environment of Strasbourg is interested in management the shallow water and the solid transport in real time for the sanitation networks. In order to be able to determine the hydraulic behavior of this type of structure, it is necessary to take into account the hydraulic discontinuities and the transitory flow regime when formulating equations and creating the associated model. The objective of this thesis is the knowledge and the control of the hydraulic parameters in shallow water
Olivas, Carrion Marc. "Communications sur le réseau d'énergie électrique d'un véhicule : modélisation et analyse du canal de propagation." Lille 1, 2006. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/2006/50376-2006-Carrion.pdf.
Full textMichelet, Jordan. "Extraction du fouillis de mer dans des images radar marin cohérent : modèles de champ de phases, méthodes de Boltzmann sur réseau, apprentissage." Electronic Thesis or Diss., La Rochelle, 2022. http://www.theses.fr/2022LAROS048.
Full textWe focus on the problem of sea clutter extraction in marine radar images. The aim is to develop image processing methods allowing us to avoid assumptions about the nature of the sea clutter and the signal of interest. On the one hand, we propose an original algorithm based on a variational approach : a multiphase model with diffuse interface. The results obtained show that the algorithm is efficient when the signal of interest has a sufficiently large signal-to-clutter ratio. On the other hand, we focus on the implementation of lattice Boltzmann schemes for convection-diffusion problems with non-constant advection velocity and non-zero source term. We describe the computation of the consistency obtained by asymptotic analysis at the acoustic scale and with a multiple relaxation time collision operator, and study the stability of these schemes in a particular case. The obtained results show that the proposed schemes allow removing the residual noise and to enhance the signal of interest on the image obtained with the first method. Finally, we propose a learning method allowing us to avoid assumptions on the nature of the signal of interest. Indeed, in addition to the variational approach, we propose an algorithm based on pulse-Doppler processing when the signal of interest is exo-clutter and has a low signal-to-clutter ratio. The results obtained from the proposed double auto-encoder, being comparable to the results provided by each of the two methods, allow validating this approach
Privault, Caroline. "Modèles mathématiques pour la gestion off-line et on-line des changements d'outils sur une machine flexible." Phd thesis, Grenoble 1, 1994. http://tel.archives-ouvertes.fr/tel-00344527.
Full textLifran, Robert. "La contrainte de liquidité et l'accumulation du patrimoine professionnel dans une perspective de cycle de vie : modèles et tests empiriques sur les données du RICA (réseau d'information comptable agricole)." Montpellier 1, 1992. http://www.theses.fr/1992MON10044.
Full textThe aim of the work is to build an life model for self employed, with endogeneous income. First, we define the type of constraints facing an selfemployed who is willing to maximize his dicounted life time utility. Second, assuming a separability between saving and borrowing for the firm, we derive a optimality condition for the firm debt from a equation which maximize ressources (disposable income and equity) of the next period. Third, we demonstrate that the euler equation is the same as the case of exogenous income, but the level of initial consumption is different. If the borrowing decision, is exogenously constrained, the rate of growth of consumption will be lower, and depends on the technology and the initial equity. We test a model for optimal debt of farmers on panel data fraom the rica. The heterogeneity of farmers facing a borrowing constraint is studied estimating a borrowing equation by age groups
Bouassam, Hamid. "Analyse et modélisation de l’effet des impédances de charge sur les performances d’une liaison CPL sur le réseau électrique domestique." Thesis, Lille 1, 2017. http://www.theses.fr/2017LIL10040/document.
Full textPowerline communication (PLC) is used to transmit high-speed data using power network as a transmission medium. However the complexity and diversity of electrical network topologies, the diversity of domestic electrical appliances connected to the network and the electromagnetic disturbances can limit the performance of this technology. The purpose of this thesis is to analyze the network characteristics and the performance of a broadband PLC link and also to highlight network topologies and loads that affect the performance of a PLC communication. The scientific approach consists firstly in characterizing the transmission channel in terms of insertion gain and then in characterizing the performance of the PLC link in terms of Shannon's capacity, in order to identify the topology characteristics that mainly influence the communication. This characterization is divided into two parts. A first experimental part studies the impact of the load and of the architecture of the electrical distribution network. A second theoretical part emphasizes on the influence of the topology and the impedances of domestic loads using a simulation tool based on the multiwire transmission line theory and the electromagnetic topology. Two transmissions are studied; a SISO (Single Input Single Output) link with the PLC transmitter and receiver connected to the network via capacitive coupling between phase and neutral, and a MIMO (Multiple Input Multiple Output) link where signals are transmitted / received between two pairs of wires : phase-neutral and earth-neutral
Gonthier, Sabine. "Systèmes modèles du réseau carré frustré : synthèses, caractérisations structurales et propriétés magnétiques : étude en fonction de la température." Toulouse 3, 2005. http://www.theses.fr/2005TOU30096.
Full textWe present synthesis, structural and magnetic characterizations of two frustrated systems on a square lattice : VMoO5 and Li2V1-xTixSiO5. The first part is related to the VMoO5 phase. After introducing its elaboration, its magnetic properties are correlated with neutron and synchrotron powder diffraction results at low temperature. These investigations are motivated by the presence of a structural instability, which occurs concomitantly with apparition of magnetic short-range correlations. VMoO5 is shown to be a frustrated 2D antiferromagnet. Moreover, neutron diffraction experiments allow the determination of the magnetic order below 40K. The study of the Li2V1-xTixSiO5 phases shows that magnetic dilution of Li2VSiO5 allows to modulate exchange interactions values. It is particularly interesting because it emphasizes the possibility to investigate the whole magnetic phase diagram of frustrated systems on a square lattice by means of well-chosen substitutions
Al-Chama, Mhd Feras. "Modélisation des effets des réseaux IP sur la transmission des médias haptiques et l'adaptation du téléapprentissage haptique à l'état du réseau." Versailles-St Quentin en Yvelines, 2009. http://www.theses.fr/2009VERS0005.
Full textLatency, jitter, packet loss are some of the network characteristics which affect haptic transmission, and consequently affect motor or haptic skill tele-transfer (telementoring). As an application, we studied haptic telementoring in virtual surgical environment. The choice of simulator was made from our study of several projects in the surgical field from which we built a platform for surgical simulation, as a basis of our haptic e-learning system. Our study had two main objectives:To determine the optimal network parameters operational zones in haptic telementoring. To model the effect of network lag on the motor skill tele-transfer quality. This model was incorporated in our haptic e-learning platform making it adaptive to network status and ensuring a robust and stable e-learning environment
Simon, Franck. "Découverte causale sur des jeux de données classiques et temporels. Application à des modèles biologiques." Electronic Thesis or Diss., Sorbonne université, 2023. http://www.theses.fr/2023SORUS528.
Full textThis thesis focuses on the field of causal discovery : the construction of causal graphs from observational data, and in particular, temporal causal discovery and the reconstruction of large gene regulatory networks. After a brief history, this thesis introduces the main concepts, hypotheses and theorems underlying causal graphs as well as the two main approaches: score-based and constraint-based methods. The MIIC (Multivariate Information-based Inductive Causation) method, developed in our laboratory, is then described with its latest improvements: Interpretable MIIC. The issues and solutions implemented to construct a temporal version (tMIIC) are presented as well as benchmarks reflecting the advantages of tMIIC compared to other state-of-the-art methods. The application to sequences of images taken with a microscope of a tumor environment reconstituted on microchips illustrates the capabilities of tMIIC to recover, solely from data, known and new relationships. Finally, this thesis introduces the use of a consequence a priori to apply causal discovery to the reconstruction of gene regulatory networks. By assuming that all genes, except transcription factors, are only consequence genes, it becomes possible to reconstruct graphs with thousands of genes. The ability to identify key transcription factors de novo is illustrated by an application to single cell RNA sequencing data with the discovery of two transcription factors likely to be involved in the biological process of interest
Blaise, Jean-Yves. "Le formalisme objet appliqué à l'étude de l'édifice patrimonial : Problèmes de modélisation et d'échanges de données sur le réseau Internet." Phd thesis, Aix-Marseille 3, 2003. http://tel.archives-ouvertes.fr/tel-00268228.
Full textNous montrons qu'une analyse a priori du corpus d'éléments physiques formant l'édifice peut grandement en faciliter l'étude. Mesure, représentations et documentation, trois exemples d'applications abordés, deviennent dans ce cadre des processus visant à renseigner le modèle et ses instances. Nous montrons que la compréhension globale de l'édifice bâti et de son évolution est mieux assurée.
Amroun, Hamdi. "Modèles statistiques avancés pour la reconnaissance de l’activité physique dans un environnement non contrôlé en utilisant un réseau d’objets connectés." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS406/document.
Full textWith the arrival of connected objects, the recognition of physical activity is experiencing a new era. New considerations need to be taken into account in order to achieve a better treatment process. In this thesis, we explored the treatment process for recognizing physical activity in an uncontrolled environment. The recognized physical activities, with only one inertial unit (accelerometer, gyroscope and magnetometer), are called elementary. Other types of context-dependent activities are called "context-based". We extracted the DCT as the main descriptor for the recognition of elementary activities. In order to recognize the physical activities based on the context, we defined three levels of granularity: a first level depending on embedded connected objects (smartphone, smartwatch and samrt TV . A second level concerns the study of participants' behaviors interacting with the smart TV screen. The third level concerns the study of participants' attention to TV. We took into consideration the imperfection aspect of the data by merging the multi sensor data with the Dempster-Shafer model. As such, we have proposed different approaches for calculating and approximating mass functions. In order to avoid calculating and selecting the different descriptors, we proposed an approach based on the use of deep learning algorithms (DNN). We proposed two models: a first model consisting of recognizing the elementary activities by selecting the DCT as the main descriptor (DNN-DCT). The second model is to learn raw data from context-based activities (CNN-raw). The disadvantage of the DNN-DCT model is that it is fast but less accurate, while the CNN-raw model is more accurate but very slow. We have proposed an empirical study to compare different methods that can accelerate learning while maintaining a high level of accuracy. We thus explored the method of optimization by particle swarm (PSO). The results are very satisfactory (97%) compared to deep neural network with stochastic gradients descent and Nesterov accelerated Gradient optimization. The results of our work suggest the use of good descriptors in the case where the context matters little, the taking into account of the imperfection of the sensor data requires that it be used and faster models
Huc, Pierre-Emmanuel. "Modélisation probabiliste du couplage d'un champ électromagnétique stochastique sur un équipement électronique dans un système multi-cavités." Toulouse 3, 2004. http://www.theses.fr/2004TOU30164.
Full textBouillot, Nicolas. "La Cohérence dans les Applications Multimédia Interactives et Distribuées : du concert réparti sur Internet aux jeux multijoueurs en réseau." Phd thesis, Conservatoire national des arts et metiers - CNAM, 2006. http://tel.archives-ouvertes.fr/tel-00145440.
Full textPelay, Johan. "Garantir la cohérence applicative lors des changements de configuration réseau : étude de cas sur la connectivité dans les Software Defined Infrastructures." Thesis, Rennes 1, 2020. http://www.theses.fr/2020REN1S001.
Full textWe believe that effective verification solutions are essential to ensure the continuity of existing services and the deployment of new services in 5G networks. This problem is not limited to verification techniques, our work also concerns the formalization of needs of a complete network service. We worked on a programming language to facilitate verification in SDN controllers. Then we defined network behavior contracts to clarify the properties to be verified to ensure the proper functioning of a service. Finally, we studied MANO to propose an extension of the standard to check the network configurations at the orchestrator level
Alvarez-Hamelin, José Ignacio. "Routage dans Internet : trafic autosimilaire, multicast et modèles de typologie." Paris 11, 2002. http://www.theses.fr/2002PA112267.
Full textThe first part of this thesis is dedicated to the study of the Internet topology, and a survey of the Internet models. We present a new model for Internet. This model will allows us to test unicast and multicast routing protocols. The second part is dedicated to multicast protocols. First, we presented a survey of construction technique for multicast trees. We propose two multicast protocols. MSDA protocol optimizes the total delay of multicast messages in a multicast tree. In order to quantify the optimization, we tested MSDA with the topologies obtained with our topology generator. MCT protocol builds the optimal multicast tree according to some predefined quality-of-service parameter. We performed simulations with ARPANET (1995) network topology in order to compare MCT with other classical multicast protocols. These simulations prove the positive impact of MCT for multicast communications. The last part is dedicated to the self-similar model of Internet traffic, and to a new quality-of-service parameter: the probabilistic congestion. This parameter allows the estimation of the rate of packet loss. Probabilistic congestion is adapted to a long-term description of the traffic, and it can be used for unicast routing protocols. We performed a simulation in order to validate our ideas (in the UUNET network and in the generated topologies from our topology model). These simulations prove the usefulness of probabilistic congestion for multicast protocols
Merino, Laso Pedro. "Détection de dysfonctionements et d'actes malveillants basée sur des modèles de qualité de données multi-capteurs." Thesis, Ecole nationale supérieure Mines-Télécom Atlantique Bretagne Pays de la Loire, 2017. http://www.theses.fr/2017IMTA0056/document.
Full textNaval systems represent a strategic infrastructure for international commerce and military activity. Their protection is thus an issue of major importance. Naval systems are increasingly computerized in order to perform an optimal and secure navigation. To attain this objective, on board vessel sensor systems provide navigation information to be monitored and controlled from distant computers. Because of their importance and computerization, naval systems have become a target for hackers. Maritime vessels also work in a harsh and uncertain operational environments that produce failures. Navigation decision-making based on wrongly understood anomalies can be potentially catastrophic.Due to the particular characteristics of naval systems, the existing detection methodologies can't be applied. We propose quality evaluation and analysis as an alternative. The novelty of quality applications on cyber-physical systems shows the need for a general methodology, which is conceived and examined in this dissertation, to evaluate the quality of generated data streams. Identified quality elements allow introducing an original approach to detect malicious acts and failures. It consists of two processing stages: first an evaluation of quality; followed by the determination of agreement limits, compliant with normal states to identify and categorize anomalies. The study cases of 13 scenarios for a simulator training platform of fuel tanks and 11 scenarios for two aerial drones illustrate the interest and relevance of the obtained results
Rouissi, Fatma. "Optimisation de la couche PHY des systèmes de communication sur le réseau d'énergie en présence de bruit impulsif." Thesis, Lille 1, 2008. http://www.theses.fr/2008LIL10042/document.
Full textThis thesis deals with the study and the suggestion of new solutions to improve high bit rate power line communications. A special interest is given to impulsive noise presence which is the most difficult transmission constraint to overcome. The first aim of this work is to analyze statistically measure results then to propose a simple and efficient noise model that will be used in a simulation tool to define accurately suitable noise cancellation techniques. Experimental measurements done in both Indoor and vehicle PLC channels allowed to deduce noise characteristics in the two environments, to compare these characteristics and to prove high effect of Indoor impulsive noise. ln next step, three models were studied: c1ass A of Middleton mode 1, Markov chains-based model and the stochastic approach. Then, a new hybrid model, that combines the stochastic approach and Markov chains, was proposed. This model is simple, easy to implement and allows a satisfying fitting to noise temporal characteristics. Comparisons of models to measured noise show the efficiency of the hybrid approach that will be used afterward. The second aim of this work is to defme new appropriate and cost-effective methods to compensate impulsive noise effect. The frrst solution is to add a noise canceller module in the PLC system receiver. This solution was studied by proposing techniques to cancel noise by estimating its power. The second solution is to use error correction methods. ln this case, three channel coding structures were developed and their performances were studied in the presence of different impulsive noise scenarios
Batany, 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.
Full textFlow 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
Leal, Gabriel da Silva Serapião. "Support à la décision pour l'analyse de l'interopérabilité des systèmes dans un contexte d'entreprises en réseau." Thesis, Université de Lorraine, 2019. http://www.theses.fr/2019LORR0001/document.
Full textEnterprise systems’ interoperability has been identified as a significant issue faced by enterprises, which need to collaborate with other companies and participate within Networked Enterprises. To achieve a higher quality of interoperability and ensure an effective collaboration, a certain number of Interoperability Requirements (IRs) should be satisfied. Thus, interoperability should be verified and continuously improved. A manner for verifying the enterprise systems’ interoperability is through the Interoperability Assessment (INAS). However, in general, the notion of “requirement” is implicit and presented as Interoperability Evaluation Criterion (IEC) in the INAS approaches. It also has been identified that the IEC interdependencies are not explicitly defined. Indeed, their interdependencies should be considered as they can support the identification of impacts on the overall system. Further, the majority of the INAS approaches are manual-conducted, which is a laborious and time-consuming process and in many times depends on the “subjective” knowledge of experts, which can be expensive in time and money when hiring external consultants. In this context, this research proposes a Knowledge-Based Interoperability Assessment System (KBIAS) for supporting decision-making within Networked Enterprises. A Design Science Research (DSR) methodology has been adopted for conducting the work. First, A Requirement Engineering (RE) approach has been adapted to elicit and define relevant IRs, which are father related with system’s components. Such IRs are used as IEC during the INAS process. To formally conceptualise the knowledge about the INAS (subsuming the set of IRs, interoperability problems and solutions), we proposed the Ontology of Interoperability Assessment (OIA). A Model-Based System Engineering approach has been applied for defining and organising the concepts of the proposed ontology. A prototype of the KBIAS using the OIA as its knowledge model has been developed in a Java platform. The developed tool can exploit the knowledge about interoperability issues and information from the as-is situation of the assessed systems for identifying potential problems and improvements. The contribution proposed in this research has been evaluated through a case study based on a real Networked Enterprise
Dumora, Christophe. "Estimation de paramètres clés liés à la gestion d'un réseau de distribution d'eau potable : Méthode d'inférence sur les noeuds d'un graphe." Thesis, Bordeaux, 2020. http://www.theses.fr/2020BORD0325.
Full textThe rise of data generated by sensors and operational tools around water distribution network (WDN) management make these systems more and more complex and in general the events more difficult to predict. The history of data related to the quality of distributed water crossed with the knowledge of network assets, contextual data and temporal parameters lead to study a complex system due to its volume and the existence of interactions between these various type of data which may vary in time and space. This big variety of data is grouped by the use of mathematical graph and allow to represent WDN as a whole and all the events that may arise therein or influence their proper functioning. The graph theory associated with these mathematical graphs allow a structural and spectral analysis of WDN to answer to specific needs and enhance existing process. These graphs are then used to answer the probleme of inference on the nodes of large graph from the observation of data on a small number of nodes. An approach by optminisation algorithm is used to construct a variable of flow on every nodes of a graph (therefore at any point of a physical network) using flow algorithm and data measured in real time by flowmeters. Then, a kernel prediction approach based on a Ridge estimator, which raises spectral analysis problems of a large sparse matrix, allow the inference of a signal measured on specific nodes of a graph at any point of a WDN
Rocha, Loures de Freitas Eduardo. "Surveillance et diagnostic des phases transitoires des systèmes hybrides basés sur l'abstraction des dynamiques continues par réseau de Pétri temporel flou." Toulouse 3, 2005. http://www.theses.fr/2006TOU30022.
Full textThe supervision and monitoring systems have a major role to the security of an industrial plant and the availability of its equipments. Forewarn the operator earliest about the deviations of the process nominal behaviour is fundamental to carry out preventive and corrective actions. Some kind of industrial plants like the chemical process and batch systems set significant complexities to the monitoring and supervision systems because of their hybrid nature (discrete and continuous interactions), the number of active variables and the complexity of theirs behaviour relations. This complexity becomes more pronounced in systems characterized by numerous operating mode changes leading to a numerous transitory phases. The monitoring of these transitory phases is a delicate issue. The large amount of variables to be taken into account leads to a difficult reasoning and interpretation of the process behaviour. In case of fault, the diagnosis becomes then a complex task. The marginal deviations of process behaviour may indicate a dysfunction that degenerates slowly or be caused by operator misbehaviour or piloting system fault. To cope with this complexity we propose a hierarchical monitoring and control system completed by a procedural decomposition proposed by the ISA88 norm, defining from the upper level the recipes, procedures, operations, phases and tasks. Our monitoring and diagnosis approach is located at two high levels of this procedural hierarchy: i) at the operation level, particularly on the transition period of operating modes where the influence relations between the variables are weekly or not known, ii) at the phase level where the influence relations are known in a period of time belonging the transition operating mode horizon. .
Chapuis, Olivier. "Influence des conditions de mouillage sur les déplacements quasi-statiques eau-air et l'évaporation en milieux poreux modèles : application à la gestion de l'eau dans les piles à combustibles PEMFC." Phd thesis, Toulouse, INPT, 2006. http://ethesis.inp-toulouse.fr/archive/00000556/.
Full textThis study is motivated by the water management problem of a proton exchange mass fuel cell. Experimental studies have been carried out and numerical tools have been designed in order to improve the knowledge on water-air quasi-static displacements with or without phase change in porous medium. Wettability impact of the porous medium on invasion rules and evaporation rate is particularly investigated. Results are then discussed within the framework of fuel cell water management issue
Boulle, Alexandre. "Diffraction des rayons X sur couches d'oxydes épitaxiées : Elaboration et analyse microstructurale." Limoges, 2002. http://www.theses.fr/2002LIMO0040.
Full textThis work deals with microstructural analysis in oxide epitaxial layers. Specific acquisition methods have been developed, such as the so-called reciprocal space mapping technique. Experiments have been carried out on a home made diffractometer devoted to the study of nanostructured materials. This set-up allows very fast reciprocal space map acquisitions (e. G. A few tens of minutes) in a high resolution mode. The two-dimensional instrumental profile has been calculated taking into account each optical element in the beam path : the X-ray source, the four-bounce monochromator, the sample and the curved position sensitive detector. This study showed that the instrumental broadening can be as low as a few thousandth of degrees in most of the scanning modes. Two oxide systems have been investigated. The first one is the ferroelectric material SrBi2Nb2O9 deposited onto SrTiO3 by sol-gel coating. Integral breadth as well as Fourier analysis of the diffraction profiles showed that the samples contain stacking faults located along the c-axis. The microstructural analysis of Y2O3 stabilized ZrO2 thin films deposited onto Al2O3 by sol-gel coating has been undertaken by profile modeling into several directions of reciprocal space taking into account physical parameters (the instrument and the microstructure). A peculiar epitaxial growth mechanism and a void/matter phase separation have been evidenced. Additionally it is shown that the layers are highly strained, and strain relaxation probably occurs by the introduction of misfit dislocations
Batt, Grégory. "Validation de modèles qualitatifs de réseaux de régulation génique : une méthode basée sur des techniques de vérification formelle." Phd thesis, Université Joseph Fourier (Grenoble), 2006. http://tel.archives-ouvertes.fr/tel-00012040.
Full textDans cette thèse, nous proposons une approche permettant de tester la validité de modèles de réseaux de régulation génique en comparant les prédictions obtenues avec les données expérimentales. Plus spécifiquement, nous considérons dans ce travail une classe de modèles qualitatifs définis en termes d'équations différentielles linéaires par morceaux (LPM). Ces modèles permettent de capturer les aspects essentiels des régulations géniques, tout en ayant une forme mathématique simple qui facilite leur analyse symbolique. Egalement, nous souhaitons utiliser les informations qualitatives sur la dynamique du système données par les changements du sens de variation des concentrations des protéines du réseau. Ces informations peuvent être obtenues expérimentalement à partir de profils d'expression temporels.
La méthode proposée doit satisfaire deux contraintes. Premièrement, elle doit permettre d'obtenir des prédictions bien adaptées à la comparaison avec le type de données considéré. Deuxièmement, étant donné la taille et la complexité des réseaux d'intérêt biologique, la méthode doit également permettre de vérifier efficacement la cohérence entre prédictions et observations.
Pour répondre à ces deux contraintes, nous étendons dans deux directions une approche précédemment développée par de Jong et collègues pour l'analyse symbolique des modèles LPM qualitatifs. Premièrement, nous proposons d'utiliser une représentation plus fine de l'état du système, permettant d'obtenir, par abstraction discrète, des prédictions mieux adaptées à la comparaison avec les données expérimentales. Deuxièmement, nous proposons de combiner cette méthode avec des techniques de model checking. Nous montrons que l'utilisation combinée d'abstraction discrète et de model checking permet de vérifier efficacement les propriétés dynamiques, exprimées en logique temporelle, des modèles continus.
Cette méthode a été implémentée dans une nouvelle version de l'outil Genetic Network Analyzer (GNA 6.0). GNA 6.0 a été utilisé pour la validation de deux modèles grands et complexes de l'initiation de la sporulation chez B. subtilis et de la réponse au stress nutritionnel chez E. coli. Nous avons ainsi pu vérifier que les prédictions obtenues étaient en accord avec la plupart des données expérimentales disponibles dans la littérature. Plusieurs incohérences ont également été identifiées, suggérant des révisions des modèles ou la réalisation d'expériences complémentaires. En dehors d'une contribution à une meilleure compréhension du fonctionnement de ces systèmes, ces deux études de cas illustrent plus généralement que, par la méthode proposée, il est possible de tester si des prédictions obtenues pour des modèles complexes sont cohérentes avec un large éventail de propriétés observables expérimentalement.
Alatriste, Contreras Martha Gabriela. "Essais sur les propriétés structurelles et la dynamique du système économique." Paris, EHESS, 2014. http://www.theses.fr/2014EHES0132.
Full textThis thesis analyses empirically the structural properties of the economy and evaluates the impact of changes in its structure on aggregate outcomes such as production and the spreading of shocks. The analysis in this thesis is part of a multidisciplinary approach where input-output is combined with complex network analysis to study the productive structure of an economy. We analyze the european union's input-output network as a whole, the input-output network of 22 member countries, and the french input-output network using a more disaggregated classification of sectors. The first chapter studies the structural properties of the economy identifying the most important sectors. In this first chapter, we investigate if global centrality measures in network analysis provide additional information of the productive structure and the role and importance of sectors in it. We found that the economy has an asymmetric structure with only a few very important sectors that have good diffusion properties. The second chapter evaluates the impact of these properties as the capability of sectors to spread shocks and form avalanches in the economy. We use three models to measure the impact of two types of sectoral shocks : a shock on final demand and a shock on technology. Results show that the asymmetrical structure of european economies makes them vulnerable to large avalanchess. Finally, third explores the mechanism generating the structure of the economy and its evolution through time driven by technological progress. In the model proposed in the third chapter sectors create new connections and change the intensity of old ones according to their centrality
Raoux, Aurore. "Approche écosystémique des énergies marines renouvelables : étude des effets sur le réseau trophique de la construction du parc éolien au large de Courseulles-sur-Mer et du cumul d'impacts." Thesis, Normandie, 2017. http://www.theses.fr/2017NORMC251.
Full textAs part of the energy transition, the French government is planning the construction of eightOffshore Wind Farms (OWF) along the English Channel and Atlantic coasts including the Courseulles-sur-mer OWF. Until now, there is no holistic study on the OWF construction and operation effects onan ecosystem taken as a whole. This thesis is the first study to lay the foundations for an ecosystemapproach of Marine Renewable Energy (MRE) through the Courseulles-sur-mer OWF example. For thata combination of innovative modelling tools was applied to 1) characterise the ecosystem structureand functioning before the OWF construction; 2) simulate the impacts of this future OWF on theecosystem structure and functioning. A food-web model and three scenarios were constructed toinvestigate the “reef” and “reserve” effects induced by the OWF on the ecosystem. Ecological NetworkAnalysis indices, other ecosystem attributes and Mean Trophic Level were derived to investigate theecosystem health and state.However, being aware that this ecosystem is threatened by multiple perturbations, there is aneed to understand how human activities interact to influence ecosystem functioning in a long termclimate change context. Thus, a holistic view of cumulated impacts on the Courseulles-sur-mer’ecosystem through the use of an oriented signed digraph was also developed. Results highlighted acombination of significant changes in the food-web structure and ecosystem functioning. These resultscan play a vital role in both decision making by improving long term planning for the marineenvironment but also as tool for communication with the public and so contribute to a betteracceptability of MRE project
Leboeuf, Mathilde. "Influence des paramètres du procédé sur les propriétés électriques et rhéologiques des polyamides chargés de noir de carbone." Phd thesis, École Nationale Supérieure des Mines de Paris, 2007. http://tel.archives-ouvertes.fr/tel-00246810.
Full textVoignier, Pierre. "Influence de la structure spatiale des pluies et du bassin versant sur les écoulements en réseau : approche à l'aide du logiciel EAUSER : Application à Saint-Etienne." Phd thesis, Ecole Nationale Supérieure des Mines de Paris, 1990. http://tel.archives-ouvertes.fr/tel-00838436.
Full textHoussamo, Issam. "Contribution à l'étude théorique, à la modélisation et à la mise en oeuvre d'un système multisource appartenant à un micro-réseau électrique : considération sur la qualité de l'énergie." Compiègne, 2012. http://www.theses.fr/2012COMP2020.
Full textThe objective of this thesis is to study, analyze and develop a multisource system belonging to a DC micro-grid with consideration of some aspects of the power quality. Chapter I presents the interest of the smart grid to ensure better coordination between distributed generation and power consumption. Having in view the prediction, a purely experimental model of photovoltaic source is developed and presented inChapter II. Furthermore, in order to extract the maximum power of the photovoltaic source, a classical algorithm is improved and the extracted energy is compared with three other methods. In Chapter III, the security system elements, the electrochemical storage and the public grid, are characterized. In the case of a storage shortage, the public grid is used to supply power to the load, but also trade back excess energy. Chapter IV presents the control of multisource system and its experimental validation. The energy management strategy taken into account is based on switching between the elements which secure the multisource system. For this, the priority is given to storage characterized by its state of charge. Thanks to this strategy, the technical feasibility of the multisource system is experimentally validated. Chapter V gives some aspects related to the improvement of the power quality: for the public grid side, a resonant controller is proposed, for the DC bus side, the pulsating power is eliminated by injecting the opposite signal supplied by the electrochemical storage
Delorme-Costil, Alexandra. "Modèles prédictifs et adaptatifs pour la gestion énergétique du bâtiment résidentiel individuel : réseaux de neurones artificiels basés sur les données usuellement disponibles." Thesis, Ecole nationale des Mines d'Albi-Carmaux, 2018. http://www.theses.fr/2018EMAC0020.
Full textThe use of predictive control permits to reduce the energy consumption of residential buildings without reducing the comfort of the inhabitant. The company BoostHeat develops a thermodynamic furnace with high energy efficiency for this purpose. Simultaneous production of domestic hot water (DHW) and heating allows many control strategies to optimize performance. The use of predictive controls makes it possible to anticipate energy needs, to take into account the impact of building inertia on indoor temperature and thus to make production management choices that minimize energy consumption. The models used today in predictive controls are binding. Indeed, these models require large amounts of data, either on a representative sample of buildings or on each modeled building. They may also need detailed studies of the building, the occupants and their consumption practices. In order to allow BoostHeat to use predictive control without going through a complex modeling step at every furnace installation, we propose adaptive models using information commonly available on a typical installation. We choose to develop artificial neural networks for the prediction on the one hand of the consumptions of DHW and on the other hand of the ambiant temperature of the building. Artificial neural networks are already used to model the energy consumption of a specific building, however our models are generic and automatically adapt to the building in which the furnace is installed. Many models are developed to study the impact of the choice of inputs, amounts of learning data and artificial neural network architecture on the accuracy of prediction. The DHW consumption prediction models are tested on three experimental cases while the indoor temperature prediction models are tested on two experimental cases and one hundred and twenty simulated cases. This makes it possible to test their adaptation to the entire French housing stock. We show, for the prediction of DHW consumption as for the indoor temperature prediction, that two weeks of collected data are sufficient for a good adaptation of the models to a specific case. The most efficient model for the prediction of domestic hot water consumption only needs the consumptions of the previous instants. The indoor temperature prediction model performs better on less isolated buildings. The results obtained are promising for the application of predictive controls on a large scale