Dissertations / Theses on the topic 'Physique des Systèmes Complexes'
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Karsai, Marton. "Comportement coopératif dans des systèmes complexes." Université Joseph Fourier (Grenoble), 2009. http://www.theses.fr/2009GRE10072.
Full textMy motivation during my PhD studies was to examine cooperative behaviour in complex systems using the methods of statistical and computational physics. The aim of my work was to study the critical behaviour of interacting many-body systems during their phase transitions and describe their universal features analytically and by means of numerical calculations. In order to do so I completed studies in four different subjects which are presented in the dissertation as follows. After a short introduction I summarized the capital points of the related theoretical results. I shortly discussed the subjects of phase transitions and critical phenomena and briefly wrote about the theory of universality classes and critical exponents. Then I introduced the important statistical models which were examined later in the thesis and I gave a short description of disordered models. In the next chapter first, I pointed out the definitions of graph theory that I needed to introduce the applied geometrical structures and I reviewed the main properties of regular lattices and defined their general used boundary conditions. I closed this chapter with a short introduction to complex networks. The next chapter contains the applied numerical methods that I used in the course of numerical studies. I write a few words about Monte Carlo methods and introduce a combinatorial optimization algorithm and its mathematical background. As a last point I describe my own techniques to generate scale-free networks. Following this theoretical introduction the obtained scientific results were presented in the following way. My first investigated subject was a study of non-equilibrium phase transitions in weighted scale-free networks where I introduced edge weights and rescaled each of them by a power of the connectivities, thus a phase transition could be realized even in realistic networks having a degree exponent γ ≤ 3. The investigated non-equilibrium system was the contact process which is a reaction-diffusion model belonging to the universality class of directed percolation. This epidemic spreading model presents a phase transition between an infected and a recovered state ordered by the ration of the recovering and infecting probability. The second problem I investigated was the ferromagnetic random bond Potts model with large values of q on evolving scale-free networks. This problem is equivalent to an optimal cooperation problem, where the agents try to find an optimal situation where the benefits of pair cooperation (here the Potts couplings) and total sum of the support, which is the same for all projects are maximized. A phase transition occurs in the system between a state when each agents are correlated and a high temperature disordered state. I examined this model using a combinatorial optimization algorithm on scale-free Barab ́si-Albert networks with homogeneous couplings and when the edge weights were a independent random values following a quasi-continuous distribution with different strength of disorder. The third examined problem was related to the large-q sate random bond Potts model also. Here I examined the critical density of clusters which touched a certain border of a perpendicular strip like geometry. Following from conformal prediction I expected the same density behavior as it was exactly derived for critical percolation in infinite strips. I calculated averages by the above mentioned effective combinatorial optimization algorithm and I compared the numerical means to the expected theoretical curves. The last investigated problem was the antiferromagnetic Ising model on two-dimensional triangular lattice at zero temperature in the absence of external field. This model was intensively studied during the last few decades, since it shows exotic features in equilibrium due to its geometrical frustration. However contradictory explanations were published in the literature about its non-equilibrium dynamical behaviour as it was characterized by a diffusive growth with logarithmic correction or by a sub-diffusive dynamics with effective exponents. My aim was to find independent evidences for one of the explanation and examine the dynamical behavior in the aging regime
Verbavatz, Vincent. "Modélisation des systèmes urbains." Thesis, université Paris-Saclay, 2022. http://www.theses.fr/2022UPASP066.
Full textCities surprise and interest a large and long-standing scientific community of economists, sociologists, geographers and historians, in which physicists and mathematicians also have their word. Cities are surprising because they exist, which is anything but obvious and reflects the essential fact that individuals are prone to group together. Cities are interesting because they are developing to the point where they have become the primary context of human life on Earth, and understanding them properly has become a global issue. Finally, it is critical to note that cities are similar across civilizations despite the multiplicity of individualities that underlie them.The urban phenomenon and the empirical similarities between the cities of the world invite us to look for common causes: this is the grounding reason for a science of cities in which we place ourselves. Our quantitative work is unique in its methodology, which stems from statistical physics, but threefold in its objectives.We focus on urban demography, the main variable of urban systems, of which we study both the static distribution and the dynamic evolution, proposing a new law of urban growth.We also study the social dynamics of cities, which characterize the economic interactions between individuals and the dynamics of segregation and gentrification. Finally, we aim at describing urban transportation, the networks on which cities rely, and quantify the non-trivial environmental and economic consequences of the interplay between private and public transport
Abarenkova, Nina. "Etudes de systèmes intégrables ou de complexes faibles, en physique du solide et systèmes dynamiques discrets." Université Joseph Fourier (Grenoble), 1999. http://www.theses.fr/1999GRE10068.
Full textMaclot, Sylvain. "Stabilité de systèmes complexes d'intérêt biologique sous rayonnements ionisants." Caen, 2014. http://www.theses.fr/2014CAEN2061.
Full textMoufid, Mohamed. "Questions de stabilité de systèmes complexes dans le champ de l'attraction terrestre." Université de Franche-Comté. UFR des sciences et techniques, 1986. http://www.theses.fr/1986BESA2025.
Full textPlazanet, Marie. "Spectroscopie vibrationnelle pour l'étude de systèmes moléculaires organiques." Habilitation à diriger des recherches, Université de Grenoble, 2010. http://tel.archives-ouvertes.fr/tel-00985257.
Full textCarra, Giulia. "Evolution of urban systems : a physical approach." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS254/document.
Full textMore than 50 % of the world population lives in urban areas and this proportion is expected to increase in the coming decades. Understanding what governs the evolution of urban systems has thus become of paramount importance.This renewed interest combined with the availability of large-scale data, allows a glimpse into the dawn of a new science of cities, interdisciplinary and based on data.Recent studies have shown the existence of statistical regularities and scaling laws for several socio-economic indicators such as fuel consumption, average commuting distance, cost of infrastructure, etc., and despite several recent attempts, the theoretical understanding of these results empirically observed remains very partial. The purpose of this thesis is to obtain a simplified, out of equilibrium model of urban growth, based on a small number of important mechanisms and which provides quantitative predictions in agreement with empirical data. For this, we will draw on studies in quantitative geography and spatial economy and we will revisit some of these old models with a new approach that integrates the tools and concepts of physics
Monnier, Xavier. "Mobilité moléculaire dans des systèmes polymères complexes anisotropes et confinés." Thesis, Normandie, 2017. http://www.theses.fr/2017NORMR021/document.
Full textThe aim of this work is to investigate the molecular dynamics of Polylactide (PLA) subjected to structural anisotropy during its processing. To do so, two experimental set-ups were used: electrospinning and flow induced crystallization. The first one leads to non-crystalline system, while the second one leads to semi-crystalline system. For each system, the microstructure is investigated to highlight the structural anisotropy induced during the processing. Different experimental techniques are used: optical microscopy, electronic microscopy, X-ray diffraction, differential scanning calorimetry (DSC) and fast scanning calorimetry (FSC). FSC proves to be useful. Due to the high scanning rates (1000 K.s-1) and the decrease of the sample mass (few tens of nanogrammes), glass transition and physical aging kinetics are beforehand investigated in the case of a wholly amorphous PLA. It is shown that high cooling rates available by FSC allow to accelerate physical aging kinetics. Molecular dynamics are then investigated through concept of cooperativity and phenomenon of physical aging. It is shown that preferential orientation induced during electrospinning leads to the formation of mesophase, which increase cooperativity, namely the intermolecular interactions. With regard to semi-crystalline system, molecular dynamics are only affected by the coupling between amorphous/crystal and the confinement effect of the crystals, rather than the structural anisotropy induced before the crystallization step
Pottier, Basile. "Les fluctuations de surface pour mesurer les propriétés de systèmes complexes en l'absence de sollicitation." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2013. http://tel.archives-ouvertes.fr/tel-00936208.
Full textCherrier, Raphaël. "Etude de systèmes de spins complexes ou désordonnés : analogies avec la transition vitreuse structurelle." Toulouse 3, 2003. http://www.theses.fr/2003TOU30136.
Full textKlein, Meyer Jean-Sébastien. "Contribution à la modélisation multi-physique des systèmes complexes dans un contexte de DFX : application à la conception de micro-mécanismes." Troyes, 2008. http://www.theses.fr/2008TROY0011.
Full textWe propose in this PhD a method to assist the designer in the choice of multi-physical tech-nologies. We propose to improve the link be-tween functional requirements of a product and technologies. This link between those two concepts is made owing to physical principles. We propose a model based on relationships between Function, Physical Principle and Tech-nology (FPPT). We present in detail this model by describing the process of creation, the enti-ties that composed the FPPT model and the functional, physical and technological parame-ters. Those parameters also support the link and help to assess the design choices. They can be use to simulate the behaviour of a design alternative very early in the design process. The FPPT model takes into account physical and technological limits issued from the physics or the technology solutions. Those limits are espe-cially useful for MEMS design. We present, trough an example (the design of a MEMS switch), how the FPPT model is integrated into a DFX approach. We also present how information given by the FPPT model and how the parameters can be used to realise more complex simulation: Multi Disciplinary Optimisation (MDO) or robustness analyses. Finally we present the specifications and the development of a software demonstrator (KBE system) to implement the FPPT model
Roy, Félix. "Dynamics of populations in large ecosystems." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASP080.
Full textThis thesis is a mathematical study of ecological models. The setup is the following: assume we delimit some forest parcel, and reference the populations of the various species it contains. If we let the ecosystem be, some species will bloom, others will go extinct. Our mathematical model predicts how the populations will change with time. In this PhD, we focus more specifically on the chaotic dynamics. In plain words, if whenever we go back to the forest parcel, the populations are different (sometimes the most abundant species is the rabbits, sometimes the boars), we will call this ecosystem chaotic. Usually in ecology, chaotic dynamics in isolated ecosystems are discarded, because they are unstable. In this work, we try to convey that chaotic dynamics are quite resilient. To do so, we introduce a specific mathematical tool. Then we perform various studies, both from pure mathematics and computer simulations, to show that lasting chaotic behaviour emerges
Schmitt, Claude. "Contribution à l'identification des paramètres physiques de systèmes complexes : application au véhicule automobile." Mulhouse, 1999. http://www.theses.fr/1999MULH0592.
Full textCraman, Michel. "Conception et réalisation d'un système de mesure automatique des permittivités diélectriques complexes." Toulouse, INPT, 1990. http://www.theses.fr/1990INPT087H.
Full textSharma, Dhruv. "Macroeconomic agent-based models : a statistical physics perspective." Thesis, Université Paris sciences et lettres, 2020. http://www.theses.fr/2020UPSLE011.
Full textAgent-based models (ABMs) have emerged as a complementary paradigm for modeling macroeconomic phenomena. Compared to other, more established models such as DSGE (Dynamic Stochastic General Equilibrium) models, ABMs provide a flexible framework for understanding the complexity of the macroeconomy while at the same time taking into account the heterogeneous nature of economic actors, institutions and markets without making overly restrictive assumptions. ABMs take a “bottom-up” approach towards macroeconomic modeling by simulating the behavior of each individual agent in the economy and then aggregating to reveal emergent phenomena such as endogenous business cycles or flash crashes. The object of this thesis is to advance a methodology commonly used in statistical physics and apply it to the study of two macroeconomic agent-based models. In both models studied here, we first determine the “phase-diagram” of the model to identify the relevant macroscopic regimes to develop an intuitive understanding of the macro-dynamics using a small subset of parameters. The first ABM presented here builds upon the paradigm of constraint satisfaction problems (CSPs) and integrates it within the model’s behavioral rules via agents’ budgetary constraints. These constraints, similar to the well-studied perceptron CSP, reveal the existence of three regimes and underscore the importance of debt for macroeconomic stability: at lowlevels of debt, the economy remains structure-less with frequent bankruptcies while high debt leads to endogenous business cycles. Between these two extremes, an intermediate regime of relative stability is found with low levels of bankruptcies for all times. Within this ABM, agents’ preferences, serving as the source of disorder in the CSP, evolve continuously in time. We thus study a simple dynamical scheme for the perceptron and discover that a rugged landscape can indeed exist with dynamic, annealed disorder. Finally, we extend the Mark-0 ABM to simulate exogenous consumption and productivity shocks due to the Covid pandemic. Whereas standard approaches design a model to understand a particular outcome, this model can generate a variety of scenarios after a Covid-like shock. Furthermore, we also investigate the efficacy of several policies, including the much-debated “helicopter money” drop, in avoiding economic collapse. We thus highlight the importance of ABMs as multi-purpose “scenario generators”, for producing outcomes that are difficult to foresee due to the intrinsic complexity of macro-economic dynamics
Konevtsova, Olga. "Théorie de Landau de cristallisation et l'approche d'ondes de densité dans les systèmes complexes." Phd thesis, Université Montpellier II - Sciences et Techniques du Languedoc, 2013. http://tel.archives-ouvertes.fr/tel-01023771.
Full textHébert-Dufresne, Laurent. "La structure communautaire comme paradigme d'organisation des réseaux complexes." Thesis, Université Laval, 2011. http://www.theses.ulaval.ca/2011/28669/28669.pdf.
Full textLorimier, Lionel. "La caractérisation dynamique des défaillances : une nouvelle approche pour la gestion active des défaillances au sein des systèmes physiques industriels complexes." Ecole Centrale de Lille, 2005. http://www.theses.fr/2005ECLI0003.
Full textSzabó, Györgyi. "Évolution des systèmes complexes : une étude des travaux philosophiques d'Ervin Laszlo, de la théorie des systèmes à la théorie d'un champ universel d'information." Thesis, Paris 5, 2014. http://www.theses.fr/2014PA05H011/document.
Full textA study of fifty years of philosophical work by Ervin Laszlo, highlighting the most important ideas, events and turning points in the thinking that led to his present-day philosophical position. This thesis reviews Laszlo’s philosophical voyage towards his uncovering and understanding of how things are and how things are becoming in terms of the evolution of complex systems as well as the purpose and meaning of human life
Sarazin, Desbois Céline. "Méthodes numériques pour des systèmes hyperboliques avec terme source provenant de physiques complexes autour du rayonnement." Phd thesis, Université de Nantes, 2013. http://tel.archives-ouvertes.fr/tel-00814182.
Full textMerheb, Rania. "Fiabilité des outils de prévision du comportement des systèmes thermiques complexes." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2013. http://tel.archives-ouvertes.fr/tel-00969036.
Full textCherrier, Raphaël. "Étude de systèmes de spins complexes ou désordonnés : analogies avec la transition vitreuse structurelle." Phd thesis, Université Paul Sabatier - Toulouse III, 2003. http://tel.archives-ouvertes.fr/tel-00840704.
Full textLéonard, Sébastien. "Hétérogénéité dynamique et échelles de longueur dans les systèmes vitreux hors-équilibre." Phd thesis, Université Montpellier II - Sciences et Techniques du Languedoc, 2007. http://tel.archives-ouvertes.fr/tel-00196528.
Full textCauffriez, Laurent. "Méthodes et modèles pour l'évaluation de la sûreté de fonctionnement de systèmes automatisés complexes : Application à l'exploitation de lignes de production - Application à la conception de systèmes intelligents distribués." Habilitation à diriger des recherches, Université de Valenciennes et du Hainaut-Cambresis, 2005. http://tel.archives-ouvertes.fr/tel-00289414.
Full textNous présentons dans cette Habilitation à Diriger les Recherches le concept de systèmes automatisés sûrs de fonctionnement et procédons à une analyse de la problématique globale de la conception de tels systèmes. Nous identifions clairement les frontières des différents systèmes constituant les systèmes automatisés sûrs de fonctionnement : processus physique, systèmes d'automatisation, systèmes de sécurité, systèmes de contrôlabilité du risque (barrières). Pour ce faire, nous nous appuyons sur la notion de service rendu.
Nous introduisons ensuite les différents concepts de sûreté de fonctionnement des systèmes en dégageant deux grands niveaux : la sûreté de fonctionnement prédictive et la gestion de la sûreté de fonctionnement avec prise en compte des risques pour l'Homme et l'environnement. Cette étude aborde les aspects normatifs incontournables pour les systèmes industriels et décline notre point de vue sur la notion de complexité. L'identification de ces grands axes de recherche en conception des systèmes automatisés sûrs de fonctionnement nous permet de situer dans la communauté scientifique nos activités de recherche, dont les contributions et résultats sont présentés dans le mémoire selon deux axes :
• L'axe I porte sur la sûreté de fonctionnement de processus physiques avec une application à l'évaluation des paramètres FMD (Fiabilité-Maintenabilité-Disponibilité) des lignes de production dans le but d'en améliorer la performance,
• L'axe II porte sur la sûreté de fonctionnement des systèmes d'automatisation à intelligence distribuée avec la proposition d'une démarche de conception de tels systèmes et d'un formalisme pour la spécification des besoins et contraintes d'architecture, l'originalité de cette méthode repose sur la volonté d'obtenir une architecture validée par des paramètres de sûreté quantifiés.
De ces travaux découlent nos activités de recherche actuelles et futures relatives à l'analyse systémique de la sûreté de fonctionnement des systèmes complexes et à l'exploration de voies de recherche pour la proposition d'une méthodologie générique, indépendante du domaine d'application, pour la conception de systèmes complexes sûrs de fonctionnement.
Haro-Sandoval, Eduardo. "Contribution à l'identification de systèmes physiques complexes. : Application à la caractérisation de la dynamique latérale d'un véhicule automobile." Mulhouse, 2006. http://www.theses.fr/2006MULH0827.
Full textThe subject of this thesis is the study of the identification methods of complex physical systems. The ultimate goal is an improvement of the parametric estimation process of lateral dynamics of a motor vehicle through an identification strategy. The study considers the existing relation between identification and modelling, the way in which the properties of the model structure influence the quality of the identification. More precisely, given that the properties of a model determine identification in a certain manner, it highlights the use of several structures of the same model for the identification of the system. A multi-structure approach is then used to benefit from the advantages of the various manners of representing a system, thanks to the complementarity of the different structures. An application based on the study of the lateral dynamics of a road vehicle is used as a support of this approach
Sahnoune, Hiba. "Aspects structuraux et électroniques de systèmes conjugués organométalliques." Thesis, Rennes 1, 2013. http://www.theses.fr/2013REN1S075/document.
Full textA theoretical study based on density functional theory (DFT) was performed on several series of organometallic mono, bi and trinuclear iron, ruthenium and platinum based complexes. The results on mononuclear iron based complexes indicate that the length of the π carbon bridge in these systems has only a minor influence on the electronic properties but affect somewhat the spectroscopic properties. A study was conducted on systems containing polycyclic aromatic ligand showing that the presence of a coordinating solvent molecule in the viscinity of the metal atom bound on top of the polycycle strongly lowers the energy barriers and consequently facilitates the haptotropic rearrangement of the grafted organoruthenium entity. The theoretical study of new systems of [2]rotaxane type has revealed that the length of the π bridge of the molecular wire threaded in a macrocycle influences the weak noncovalent interaction energies in these systems. It has been shown that these noncovalent interactions are mainly due to hydrogen bonds formed between the macrocycle and the threaded molecular wire
Fléchon, Elsa. "Définition d'un modèle unifié pour la simulation physique adaptative avec changements topologiques." Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10284/document.
Full textThe work made during my PhD, respond to the problematic of physical simulation of the behavior of deformable objects subject to topological changes in interactive time. My work resulted in the definition of a new unified model coupling a complete topological model and a physical model for physical simulation of deformable objects decomposed in surface as volume elements, while performing during this simulation topological changes such as cutting or subdivision local of a mesh element. This operation allowed us to propose an adaptive method where mesh elements are refined during the simulation according to a geometric criterion. For the topological model of our unified model, we made the choice of combinatorial maps and more particularly linear cellular complexes. Their main advantage of the latter is the simplicity of its equations, its intuitive implementation, its interactivity and its ease to handle topological changes. Finally, the definition of a unified model allowed us to propose a model avoiding duplication of information and facilitate the update after topological changes
Gutierrez, Guillen Gabriela. "Qualitative study of physical phenomena through geometry of complex foliations." Electronic Thesis or Diss., Bourgogne Franche-Comté, 2024. http://www.theses.fr/2024UBFCK012.
Full textThrough an in-depth exploration of the underlying geometry, we provide a full mathematical description of the tennis racket effect, which is a geometric phenomenon observed in free rotational dynamics of rigid bodies. We examine the existence, origin, and robustness of this effect using the interplay between complex and real geometries. We also detect signatures of physical constraints on the moments of inertia of the body, in the geometric structure of the tennis racket effect. The analysis is extended to closely related phenomena such as the Dhzanibekov effect, the monster flip, and the Montgomery phase.The second part of the thesis focuses on Hamiltonian monodromy, which is the simplest topological obstruction to the existence of global action-angle coordinates for a completely integrable system. We show that the use of spectral Lax pairs provides a complex geometric structure that enables the study of Hamiltonian monodromy and the calculation of the corresponding monodromy matrix.Throughout this research work, we adopt a general framework that employs complex foliations to provide a geometric structure for the problems under study, leading to a deeper understanding of these phenomena
Tomezak, Maxime. "Radiothérapie du cancer : de la physique de l’ADN irradié à la dormance tumorale." Thesis, Lille 1, 2016. http://www.theses.fr/2016LIL10205/document.
Full textRadiotherapy uses ionizing radiations in order to eradicate cancer cells mainly through the generation of DNA double-strand breaks. A side effect of radiotherapy is the emergence of second cancer, preferentially at the border of the treated volume, where normal cells receive some non-lethal leaking radiations. These second cancers are mainly sarcomas and develop with a latency of 3 to 20 years. We have determine the distribution of DNA damage (SSBs and DSBs) both in-and at the border of the irradiation field following various conditions of irradiation. We also investigated DNA damages and induction of senescence after multi-session of treatment. Fluorescent detection of 53BP1 and XRCC1 foci was used as a marker of DSBs and SSBs respectively. Finally senescence state has been tested by measurement of SA-beta-galactosidase activity. We also developped a theoretical agent-based model of cell evolution under the action of cytotoxic treatments, such as radiotherapy or chemotherapy. The major features of cell cycle and proliferation, cell damage and repair, and chemical diffusion are included. Cell evolution is based on a discrete Markov chain. Two showcase applications of the model are then presented (survival curves and bystander effect)
Metzig, Cornelia. "A Model for a complex economic system." Thesis, Grenoble, 2013. http://www.theses.fr/2013GRENS038/document.
Full textThe thesis is in the field of complex systems, applied to an economic system. In this thesis, an agent-based model has been proposed to model the production cycle. It comprises firms, workers, and a bank, and respects stock-flow consistency. Its central assumption is that firms plan their production based on an expected profit margin. A simple scenario of the model, where the expected profit margin is the same for all firms, has been analyzed in the context of simple stochastic growth models. Results are a firms' size distribution close to a power law, and tent-shaped growth rate distribution, and a growth rate variance scaling with firm size. These results are close to empirically found stylized facts. In a more comprehensive version, the model contains additional features: heterogeneous profits margins, as well as interest payments and the possibility of bankruptcy. This relates the model to agent-based macroeconomic models. The extensions are described theoretically theoretically with replicator dynamics. New results are the age distribution of active firms, their profit rate distribution, debt distribution, bankruptcy statistics, as well as typical life cycles of firms, which are all qualitatively in agreement with studies of firms databases of various countries.The proposed model yields promising results by respecting the principle that jointly found results may be generated by the same process, or by several ones which are compatible
Cabaret, Olivier. "Caractérisation physique et approche numérique du rôle des aquitards dans les systèmes aquifères multicouches - Application au complexe tertiaire nord-aquitain." Phd thesis, Université Michel de Montaigne - Bordeaux III, 2011. http://tel.archives-ouvertes.fr/tel-00626915.
Full textMorand, Jules. "Dynamics of long range interacting systems beyond the Vlasov limit." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066624/document.
Full textLong range interactions concern numerous natural systems. A notable example is the one of the gravitation which is relevant in the case of the study of a stars system or galaxy clusters. In particular, these systems does not respect the additivity of thermodynamical potential and present a dynamics dominated by collective effects. One of the most remarkable feature is that, after a very rapid evolution, these systems remains trapped into quasi-stationary states up to a very long time (diverging with the system size). It is only on longer time scales, that simulations have shown that the system relaxes to thermal equilibrium.Quasi-stationary states are theoretically interpreted as solutions of the Vlasov equation. This mean filed equation represents a very good approximation of the dynamics of long range systems in the limit of a large number of particles. Firstly we give a limit on the validity of the Vlasov equation depending of the range of the pair force and on its short scales regularisation. In a second part, using theoretical an numerical approach, we study the modification of the dynamics of long range systems when subjected to different kinds of non-Hamiltonian perturbations. In particular, the robustness of quasi-stationary states, in presence of this different perturbations is analysed in details
Spiesser, Christophe. "Méthode de simulation appropriée aux systèmes complexes : preuve de concept auto-adaptative et auto-apprenante appliquée aux transferts thermiques." Thesis, Ecole nationale des Mines d'Albi-Carmaux, 2017. http://www.theses.fr/2017EMAC0005/document.
Full textAs computing power increases, engineers and designers tackle increasingly complex problems using simulation (multiphysics, multiscale, intricated geometries ...). In this context, discretization-based quadratures (FDM, FEM, FVM) show their limit: the need of a great number of sub-domains which induces prohibitive consumption of RAM and CPU power. The Monte Carlo method appears to be more appropriate, but the difficulty to build probabilistic models of complex systems forms a bottleneck. A systemic approach is proposed to alleviate it and is implemented to create a proof-of-concept dedicated to the coupled heat transfer simulation. After a successful validation step against analytical solutions, this tool is applied to illustrative cases (emulating heat transfer in buildings and in solar heating systems) in order to study its simulation capabilities.This approach presents a major beneficial behavior for complex systems simulation: the computation time only depends on the influential parts of the problem. These parts are automatically identified, even in intricate or extensive geometries, which makes the simulation self-adaptive. In addition, the computational performance and the system scale ratio are completely uncorrelated. Consequently, this approach shows an exceptional capacity to tackle multiphysics and multiscale problems. Each temperature is estimated using exploration paths. By statistically analyzing these paths during the process, the tool is able to generate a reduced predictive model of this physical quantity, which is bringing a self-learning capacity to the simulation. Its use can significantly improve optimization and control of processes, or simplify inverse measurements. Furthermore, based on this model, an uncertainty propagation analysis has been performed. It quantifies the effect of uncertainties affecting boundary conditions on the temperature. Finally a Particle Swarm Optimization (PSO) process, based on simulations done by the framework, is successfully carried out
Léonard, Sébastien. "Hétérogénéité dynamique et échelles de longueur dans les systèmes vitreux hors-équilibre." Phd thesis, Montpellier 2, 2007. http://www.theses.fr/2007MON20142.
Full textOur theoretical understanding of the glass transition remains incomplete. The microscopic origin of the dynamic slowing down can be explained by the presence of spatial heterogeneities which have been observed experimentally and numerically in various glass-formers. In this work, we characterize the dynamical heterogeneities during a nonequilibrium dynamics. Our analysis is based on detailed theoretical and numerical results for the activated aging regime of simple kinetically constrained models. We shown that fragile glasses close to their glass transition exhibit a lifetime of dynamic heterogeneities larger than their relaxation time. We find also that the aging dynamics of these models can be described in term of very special class of random walks. Moreover, the measurement of the violation of the fluctuation-dissipation theorem leads to negative effective temperature which is a direct consequence of the thermally activated dynamics
Butano, Matteo. "Mean-Field Games Applied to Pedestrian Dynamics." Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASP064.
Full textThis thesis explores pedestrian dynamics through experimental observations and simulations, focusing on the operational layer of pedestrian movement. Experiments involving a controlled crowd and a moving cylindrical obstacle, reveal that pedestrians exhibit anticipatory behaviors that deviate from granular behavior. The thesis challenges two existing pedestrian dynamics models, of different complexity showing their limitations in capturing the observed anticipatory behaviors. These models are found to be too myopic, focusing on short-term decisions without adequately accounting for long-term anticipations. To address these shortcomings, this work proposes a model based on the theory of Mean-Field Games (MFG). MFG models, which combine optimal control and game theory, describe interactions among a large number of agents via their average density, simplifying the mathematical framework. The MFG model successfully predicts the experimental anticipation patterns by incorporating a discount factor that adjusts the weight of future events in the optimization process. Additionally, the thesis presents two corollary projects. The first has the goal to integrate MFG with agent-based microscopic models to handle scenarios requiring detailed individual interactions, such as evacuations. The second explores using Physics Informed Neural Networks to solve MFG equations
Dichio, Vito. "The exploration-exploitation paradigm : a biophysical approach." Electronic Thesis or Diss., Sorbonne université, 2023. http://www.theses.fr/2023SORUS402.
Full textThe study of living systems is notoriously challenging. The often-quoted daunting complexity of biological systems is primarily due to the intricacies of their interactions, their multiple organisation levels and their dynamic nature. In the quest to understand this complexity, parallels drawn with standard physics – in particular, statistical physics -- are both useful and of limited use. On the one hand, they provide a rich set of theoretical and methodological building blocks for constructing theories and designing experiments. On the other hand, life also unfolds according to principles that are unparalleled in the physics of conventional matter. A crucial difference lies in the notion of function: biological systems are shaped by the need to perform specific tasks. A general problem for living systems is to find and promote those configurations that yield improved or optimal functions, we call this the exploration-exploitation (EE) problem. One specific instance of the above is found in evolutionary biology. There, random genetic mutations sustain the exploration of the configuration space, with those leading to higher reproductive success being favoured by natural selection. Inspired by the latter, we develop a novel formalism that encodes a general exploration-exploitation dynamics for biological networks. In particular, our EE dynamics is represented as an exploration of a functional landscape and consists of stochastic configuration changes combined with the state-dependent optimisation of an objective function (F metric). We begin by investigating its main features through the study of simple, analytically tractable functional landscapes. We deploy simulations for more general and complex applications. We then turn to the brain wiring problem, i.e., the development of an individual's nervous system during its early life. We argue that this is another specific instance of the EE problem and therefore can be addressed by using our theoretical framework. In particular, we focus on brain maturation in the nematode C.elegans, the only organism for which a complete network of neurons and neuronal connections has been reconstructed, at multiple developmental time points (seven). We fix the network at birth and use the adult stage to infer (i) a parsimonious maxent (ERG) description of the F metric for the worm brain and (ii) the two parameters of our EE dynamics. According to the topography of its functional landscape, the adult brain is characterised by a tendency to form both triads and high degree nodes. We demonstrate that our EE dynamics in such landscape is capable of tracking down the entire developmental history. In particular, we show that the trajectory we obtain closely reproduces the other experimental time points that we did not use for inference. This is true both in the space of model statistics and for a number of other network properties. Additionally, we discuss a micro-level interpretation of the EE dynamics in terms of the underlying synapse formation process. Our study is a first step towards the system-level understanding of the development of a natural brain and can be extended (i) to encompass more complex functional landscapes, (ii) to different organisms than the C. elegans and (iii) to several different problems than the brain wiring. Indeed, we posit that the exploration-exploitation paradigm is among those life-specific principles that we are just beginning to uncover
Orio, Maylis. "Étude par la Théorie de la Fonctionnelle de la Densité des propriétés électroniques et magnétiques de complexes de fer. Application aux systèmes de types Catalase et Fer-Soufre." Grenoble 1, 2007. http://www.theses.fr/2007GRE10184.
Full textThis PhD work is divided into two parts and aims at modeling some spectroscopic quantities (Mössbauer, EPR and magnetism) measured in iron containing bioinorganic systems with Density Functional Theory (DFT). The first part of this work deals with the theoretical calculation of two Mössbauer parameters: the isomeric shift and the quadrupole splitting ΔEQ. First, correlations between calculations and experimental data have been established for simple iron complexes. Second, we have been interested in the investigation of a biological system, catalase, an iron containing heme, and we have tried to characterize its various forms. The second part of this work was devoted to rationalizing the variations of two parameters: the EPR g-average value, gav (= (∑gi)/3), and the effective exchange coupling constant Jeff. We have considered a set of [2Fe-2S] clusters in biological systems (ferredoxins, Rieske proteins, xanthine oxydases, etc). We have modeled these quantities with a phenomenological model involving the competition between two antagonist terms: the double exchange term B which reflects electronic delocalization between the iron sites and the trapping term ΔE which preferentially localizes the reducing electron on one iron site. We have been able to express analytically gav et Jeff as a function of the ratio ΔE/B allowing us to explain the source of the observed variations
Halbert, Stéphanie. "Étude du comportement dynamique de systèmes catalytiques greffés sur silice." Phd thesis, Université Montpellier II - Sciences et Techniques du Languedoc, 2013. http://tel.archives-ouvertes.fr/tel-01005016.
Full textKekatos, Nikolaos. "Vérification formelle des systèmes cyber-physiques dans le processus industriel de la conception basée sur modèle." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAM081/document.
Full textCyber-Physical Systems form a class of complex, large-scale systems of frequently safety-critical nature in various industrial applications. Formal verification approaches can provide performance and safety guarantees for these systems. They require three elements: a formal model, a formal verification method, and a set of formal specifications. However, industrial models are typically non-formal, they are analyzed in non-formal simulation environments, and their specifications are described in non-formal natural language. In this thesis, we aim to facilitate the integration of formal verification into the industrial model-based design process.Our first key contribution is a model transformation methodology. Starting with a standard simulation model, we transform it into an equivalent verification model, particularly a network of hybrid automata. The transformation process addresses differences in syntax, semantics, and other aspects of modeling. For this class of formal models, so-called reachability algorithms can be applied to verify safety properties. An obstacle is that scalable algorithms exist for piecewise affine (PWA) models, but not for nonlinear ones. To obtain PWA over-approximations of nonlinear dynamics, we propose a compositional syntactic hybridization technique. The result is a highly compact model that retains the modular structure of the original simulation model and largely avoids an explosion in the number of partitions.The second key contribution is an approach to encode rich formal specifications so that they can be interpreted by tools for reachability. Herein, we consider specifications expressed by pattern templates since they are close to natural language and can be easily understood by non-expert users. We provide (i) formal definitions for select patterns that respect the semantics of hybrid automata, and (ii) monitors which encode the properties as the reachability of an error state. By composing these monitors with the formal model under study, the properties can be checked by off-the-shelf fully automated verification tools.Furthermore, we provide a semi-automated toolchain and present results from case studies conducted in collaboration with industrial partners
Martinet, Lucie. "Réseaux dynamiques de terrain : caractérisation et propriétés de diffusion en milieu hospitalier." Thesis, Lyon, École normale supérieure, 2015. http://www.theses.fr/2015ENSL1010/document.
Full textIn this thesis, we focus on tools whose aim is to extract structural and temporal properties of dynamic networks as well as diffusion characteristics which can occur on these networks. We work on specific data, from the European MOSAR project, including the network of individuals proximity from time to time during 6 months at the Brek-sur-Mer Hospital. The studied network is notable because of its three dimensions constitution : the structural one induced by the distribution of individuals into distinct services, the functional dimension due to the partition of individual into groups of socio-professional categories and the temporal dimension.For each dimension, we used tools well known from the areas of statistical physics as well as graphs theory in order to extract information which enable to describe the network properties. These methods underline the specific structure of the contacts distribution which follows the individuals distribution into services. We also highlight strong links within specific socio-professional categories. Regarding the temporal part, we extract circadian and weekly patterns and quantify the similarities of these activities. We also notice distinct behaviour within patients and staff evolution. In addition, we present tools to compare the network activity within two given periods. To finish, we use simulations techniques to extract diffusion properties of the network to find some clues in order to establish a prevention policy
Martinez, Nicolas. "Etudes structurales et dynamiques du système de transport bactérien FhaB/FhaC et du complexe de réplication des Rhabdoviridae." Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00721739.
Full textHolovatch, Taras. "Réseaux de transport complexes : résilience, modélisation et optimisation." Phd thesis, Université Henri Poincaré - Nancy I, 2011. http://tel.archives-ouvertes.fr/tel-00652784.
Full textBoussoualem, Mourad. "Contribution à l'optimisation de la qualité de régulation lumineuse de films composites : études physicochimiques aux interfaces matrices-fluides complexes." Littoral, 2005. http://www.theses.fr/2005DUNK0127.
Full textThis work is devoted to the study of the relationship existing between the structural properties and the elctro-optical behaviour of liquid crystal/polymer dispersions. In particular, the physical parameters influencing the electrical and electrooptical characteristics are investigated. Polarization field effect, confinement (surface/volume ratio) effect, and anchoring conditions at the polymer/liquid crystal interface are studied. First, thermophysical, optical and electrical properties of a model system are investigated. This system consists in a perfectly characterized polymer (monodisperse polystyrene (PS)) and a nematic liquid crystal (5CB). Calorimetry (DSC) and polarized optical microscopy (POM) were used to establish the phase diagram which exhibits a upper critical solution temperature (USCT) shape with a wide immiscibility gap (Isotropic-Isotropic). Broadband dielectric spectroscopy experiments have been carried showing that a relaxation mechanism exists at low frequency. This mechanism is closely related to the heterogeneous morphology of the sample. The correlationbetween the dielectric and electro-optical studies showed that in the vicinity of the low frequency absorption domain a drastic decrease in the optical transmittance occurs. This phenomenon can be related to an interfacial polarisation process (Maxwell-Wagner-Sillars effect (MWS)) resulting from a charge accumulation at the droplet-polymer interface. Second, the influence of confinement on the order parameter of the confined liquid crystal phase and polarisation field effects have been investigated on PS/8CB mixtures. DSC measurements allowed to estimate the phase-separated liquid crystal (8CB) fraction, which was found in the range of 55 % for both micron-size and submicron-size droplets. X-ray diffraction (XRD) experiments showed that smectic 8CB confined to micron-size cavities adopt bulk-like properties, i. E. , a partial bilayer structure, whereas in submicron-size droplets the layer spacing of the smectic phase is increased due to the strong bending deformations inducing by the high curvature of the cavity walls. Third, a comparative study of two structurally close systems showed the ability to impose given anchoring conditions using various lateral substituants for the polymer matrix. Best electro-optical performances were obtained with the system showing a planar anchoring in the droplets. This result was related to faster reorientation dynamics of the liquid crystal droplets, in the case of a planar anchoring compared to that of a homeotropic anchoring of the liquid crystal molecules. Finally, "all plastic" display devices were reported combining the mechanical performance of polymer dispersed liquid crystal film and the use of plastic substrates covered with conducting organic electrodes. A low frequency relaxation process was observed corresponding to interfacial polarization process (MWS effect) as well as a relaxation mechanism at high frequency associated with a charge accumulation at the electrode surface
Moran, José. "Statistical physics and anomalous macroeconomic fluctuations." Thesis, Paris, EHESS, 2020. http://www.theses.fr/2020EHES0106.
Full textHow do microscopic perturbations at the level of an individual grow to become macroscopic fluctuations of the whole economy? Despite decades of effort, this puzzle remains open. In this work, I tackle this problem using methods and techniques from statistical physics. Beginning with a thorough analysis of power law distributions, I argue that understanding their origin and properties helps in elucidating their socio-economic consequences. I then explore a model of an economy where firms interact through a {\em production network} in a way that causes them to be intrinsically prone to amplify fluctuations. Later on, I conduct an empirical survey of the statistical properties of firm growth rates and provide a framework to study their dynamics. I finally move onto models where non-trivial collective phenomena arise from imitation and memory effects at the level of the individual, highlighting the need of accounting for complexity in economic modelling
Courtat, Thomas. "Promenade dans les cartes de villes - Phénoménologie mathématique et physique de la ville - une approche géométrique." Phd thesis, Université Paris-Diderot - Paris VII, 2012. http://tel.archives-ouvertes.fr/tel-00714310.
Full textBigot, Dimitri. "Contribution à l'étude du couplage énergétique enveloppe / système dans le cas de parois complexes photovoltaïques (PC - PV)." Phd thesis, Université de la Réunion, 2011. http://tel.archives-ouvertes.fr/tel-00766755.
Full textAbdeljabbar, Nourhene. "Conception d'une méthodologie appliquée aux modèles dynamiques multi-physiques à topologie dynamique." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLC016.
Full textMechatronic systems modelling requires the same type of methodology for the design and prototyping of mechatronic devices. Unified and integrated engineering must be deployed. Various approaches are currently proposed to achieve multi-physics modeling such as graph theory, equational approaches or techniques. In this context, the objective of our research work is the design of a methodology applied to dynamic multi-physical models with dynamic topology. For such a contribution, it is necessary to start from an existing approach. This approach focuses on topological modelling since it is based on topological collections and transformations. This topological approach is used to model mechatronic systems.Its strong point is the separation of topology (interconnection law) and behavior law (physical) which allows the simplification of the modeling of complex systems that can be described as a set of local interactions between elementary entities. The thesis therefore proposes a new methodology named 4Mo(DS)2 which relates to multilevel, multi-physical and multi-domain modeling based on dynamic systems that have dynamic structures. This methodology allows the topological modeling of dynamic multi-physical dynamic topology models during the design phase while taking into account topological modifications, control and command as well as the integration of dimension two into their topological structure
Orio, Maylis. "Etude par la Théorie de la Fonctionnelle de la Densité des propriétés électroniques et magnétiques de complexes de fer. Application aux systèmes de types Catalase et Fer-Soufre." Phd thesis, Université Joseph Fourier (Grenoble), 2007. http://tel.archives-ouvertes.fr/tel-00178652.
Full textFoyart, Guillaume. "Fractures et instabilités de fluides viscoélastiques en cellule de Hele-Shaw." Phd thesis, Université Montpellier II - Sciences et Techniques du Languedoc, 2013. http://tel.archives-ouvertes.fr/tel-01019314.
Full textSuaud, Nicolas. "Calculs ab initio des intégrales de saut et d'échange dans des composés de métaux de transition." Phd thesis, Université Paul Sabatier - Toulouse III, 2000. http://tel.archives-ouvertes.fr/tel-00007277.
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