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Comportements collectifs d'animaux et physique hors-équilibre

Abstract : This dissertation presents two-dimensional out-of-equilibrium stochastic models of animal collective motion. The aim of the study is not a realistic description but, rather, the understanding of a few minimal components. In the first part, we study how a uniformly space-distributed population achieves macroscopic motion. Two transitions are observed and entirely characterized. One is second order, the second is first order. At the threshold, the diffusion is anomalous, and this allows the description of an experiment of passive beads in a bacterial bath. The second part is devoted to the study of cohesive animal groups of arbitrary structure : fixed or in motion, with or without internal order. We define each phase by its diffusive, cohesive, microscopic, and macroscopic properties. We show the existence of infinite cohesive herds in a open space and we draw the related phase diagram. Lastly, we show that, at the onset of collective motion, the internal order of the herd is destabilized, leading to some astonishing and complex structures.
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https://tel.archives-ouvertes.fr/tel-00002435
Contributor : Marc Gingold <>
Submitted on : Thursday, February 20, 2003 - 7:01:42 PM
Last modification on : Friday, March 5, 2021 - 3:10:39 PM
Long-term archiving on: : Friday, April 2, 2010 - 6:53:22 PM

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  • HAL Id : tel-00002435, version 1

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Guillaume Grégoire. Comportements collectifs d'animaux et physique hors-équilibre. Physique [physics]. Université Paris-Diderot - Paris VII, 2003. Français. ⟨tel-00002435⟩

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