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Physique statistique et modéles non-linéaires
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Our team tackles theoretically several subjects where non-linearities trigger unusual properties in statistical physics: systems with long range interactions, geophysical turbulent flows, climate dynamics…
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Ondes, Ecoulements et Fluctuations
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Physique statistique, traitement du signal et théorie de l'information
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We apply concepts from Statistical Physics, nonlinear Physics and Information Theory to define or refine signal processing tools.
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SIgnaux, SYstèmes & PHysiquE
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Problèmes inverses en imagerie
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The group has recently developed an activity focused on the resolution of inverse problems and optimisation. The inverse problems we consider can be split in three topics :
- Image restoration
- Non-stationarity and optimisation
- Change-point detection and segmentation for regularity estimation
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SIgnaux, SYstèmes & PHysiquE
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Signaux ou images en biologie ou génomique
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SIgnaux, SYstèmes & PHysiquE
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Signaux sur graphes et réseaux complexes
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Data appear often with a mixture or relational properties –coded by graphs or networks–, and attributes —naturally dealt as signals (possibly multivariate signals). An activity of the group is to study signal an ddata processing for these types of data, both for graph signals (when a signal is indexed by a graph) and for complex networks where the signal of interest is the network itself. In both cases, the group has a specific interest in networks which are dynamic, or for which a multiscale approach is fruitful.
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SIgnaux, SYstèmes & PHysiquE
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Physique statistique
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This theme is historically one of the first research area of the laboratory, and it actually gathers activities being conducted in several groups. It is characterized by frequent and fruitful collaborations between theoreticians and experimentalists within the laboratory.
Statistical physics is devoted to the study of the collective and macroscopic behavior of systems composed of a large number of elementary entities that interact one with the other. One speaks of "complex system" when the dynamics, or the structures that appears within the system, exhibit a rich variety of behaviors, while the microscopic entities the system is made of, and the interactions between these entities, are a priori simple. It may be noticed that the sensitivity to the initial conditions, as well as the large number of possible evolutions, play a major role in the emergence of non-trivial collective behaviors in such systems.
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Physique Théorique
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Théorèmes de fluctuation et bruit thermique
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In out of equilibrium or mesoscopic systems, fluctuations play an important role and provide a unique tool to probe the underlying physics. Our team develops various experiments to measure directly this noise and test statistical physics approaches : fluctuations theorems, nano-mechanics, confined phase transitions…
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Ondes, Ecoulements et Fluctuations
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Traitement du signal non-stationnaire
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The group has a strong history of studying nonstationary signal processing, ranging from theoretical analalysis or development of approaches such as time-frequency methods, data-driven decompositions (e.g., Empirical Mode Decomposition), practical characterization of stationarity and non-stationarity. Many applications of these methods have been put forward as well by the group.
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SIgnaux, SYstèmes & PHysiquE
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Turbulence des fluides, fluides quantiques
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La turbulence des fluides et le traitement du signal sont des domaines intimement liés. D'une part, les mesures expérimentales d'un écoulement turbulent, et les simulations numériques des équations de Navier-Stokes, ont bénéficié des techniques et développements de la science du signal. D'une autre part, la nécessité de prendre en compte l'aspect multidimensionel des grandeurs liées à la turbulence, et la volonté de construire des modèles aléatoires capables de rendre en compte des statistiques particulières observées dans les écoulements, est un territoire fécond pour le développement d'approches multivariées des signaux. L'équipe Sisyphe depuis longtemps s'attèle à développer ce domaine pluridisciplinaire.
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SIgnaux, SYstèmes & PHysiquE
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