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Matière condensée
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D. Carpentier, P. Degiovanni, P. Delplace, A. Fedorenko, P. Holdsworth, F. Mezzacapo, E. Orignac, T. Roscilde, L. Savary.
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Physique Théorique
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Physique mathématique
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A. Alastuey, F. Delduc, M. Geiller, K. K. Kozlowski, G. Niccoli, E. Livine, M. Magro, J. M. Maillet, H. Samtleben
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Physique Théorique
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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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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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Application biomédicale en signal et images
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SiSyPh research team is putting significant efforts into developing signal/image processing tools for biomedical applications. On the image processing side, an efficient reconstruction procedure mixing on non-smooth convex optimization to balance data fidelity and regularization provides an efficient reconstruction procedure for high resolution image from low resolution records. On the signal processing side, statistical tools are customized to analyze scale invariance in heart rate variability (notably in the context of intrapartum fetal heart beat analysis) as well as in infraslow brain activity. It notably permits to relate scale invariance in background brain activity to functional connectivity and to quantify task-rest modulation of brain scaling.
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SIgnaux, SYstèmes & PHysiquE
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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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Invariance d'échelle, multifractales et ondelettes
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L'analyse et la modélisation des phénomènes d'invariance d'échelle constituent des thèmes de recherche au long court de l'équipe SiSyPhe.
Les efforts portent d'abord depuis longtemps sur la définition, la conception et la synthèse numérique de processus stochastiques
aux propriétés d'invariance d'échelle prescrites a priori, conjointement soit avec d'autres propriétés statistiques (distributions, dépendances,...), soit avec des propriétés géométriques (divergence nulle, vorticité prescrite,..) pour ajuster des applications particulière (la turbulence hydrodynamique en particulier). Des outils statistiques sont également construits et étudiés, théoriquement et pratiquement, visant à tester la présence d'invariance d'échelle, à estimer les paramètres de scaling ou les bornes de la gamme d'échelle. Les efforts récents portent notamment sur l'étude des signaux multivariés et l'étude des champs (multidimensionnels) compliqués par une éventuelle anisotropie.
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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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Thèmes de recherche
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Signaux ou images en biologie ou génomique
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SIgnaux, SYstèmes & PHysiquE
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