Asynchronous Interactive Physical Simulation

This document introduces a multi-agent framework for real-time physical simulation. Unlike classical physical simulators, no shared discrete time-line is imposed to simulated objects. Each simulated object is an autonomous agent that can maintain its simulation state, and possibly modify its behavior by checking its environment. Decision schemes are proposed that enable objects to locally adapt their computation time, in order to maintain approximate global synchronization. Results and measures are presented, especially regarding time management and simulation synchronization in regard of classical simulation methods. Examples are shown, outlining some of the practical advantages such a framework provides

Tracking ultrafast solid-state dynamics using high harmonic spectroscopy

WWe establish time-resolved high harmonic generation (tr-HHG) as a powerful spectroscopy method for tracking photoinduced dynamics in strongly correlated materials through a detailed investigation of the insulator-to-metal phase transitions in vanadium dioxide. We benchmark the technique by comparing our measurements to established momentum-resolved ultrafast electron diffraction, and theoretical density functional calculations. Tr-HHG allows distinguishing of individual dynamic channels, including a transition to a thermodynamically hidden phase. In addition, the HHG yield is shown to be modulated at a frequency characteristic of a coherent phonon of the equilibrium monoclinic phase over a wide range of excitation fluences. These results demonstrate that tr-HHG is capable of tracking complex dynamics in solids through its sensitivity to the band structure

Tracking ultrafast solid-state dynamics using high harmonic spectroscopy

We establish time-resolved high harmonic generation (tr-HHG) as a powerful spectroscopy for photoinduced dynamics in strongly correlated materials through a detailed investigation of the insulator-to-metal transitions in vanadium dioxide. We benchmark our technique by comparing our measurements to established momentum-resolved ultrafast electron diffraction, and theoretical density functional calculations. Tr-HHG allows distinguishing of individual dynamic channels, including a transition to a thermodynamically hidden phase. In addition, the HHG yield is shown to be modulated at a frequency characteristic of a coherent phonon in the equilibrium monoclinic phase over a wide range of excitation fluences. These results demonstrate that tr-HHG is capable of tracking complex dynamics in solids through its sensitivity to the band structure.Comment: 20 pages and 4 figures main text, 8 pages and 4 figures supplementary informatio

Objets autonomes en simulation physique temps-réel

Cette thèse s'inscrit dans le cadre de la simulation physique interactive. Notre objectif est de proposer une plate-forme de simulation suffisamment générique et flexible pour simplifier le développement et la réutilisation d'applications de simulation. Notre proposition repose sur le concept d'objets autonomes, capables de déterminer eux-mêmes leur état à chaque instant de la simulation. Pour garantir que la simulation soit visuellement réaliste malgré des objets potentiellement hétérogènes, nous introduisons une synchronisation temporelle relâchée. Nous montrons que ce choix de conception se prête de manière naturelle à la simulation collaborative. Notre approche se veut robuste et peu dépendante des performances du réseau. Elle se base sur un traitement local des objets simulés, couplé à un système asynchrone de correction, garantissant dans le cas des simulations déterministes, de manière aymptotique et avec vitesse de convergence dépendant des performances réseau, une position d'équilibre physiquement plausible, et partagée sur tous les postes. Enfin, pour illustrer le potentiel de cette plate-forme, et souligner le fait que celle-ci peut intégrer facilement des objets physiques associés à de nouvelles fonctionnalités evoluées, sans connaissance préalable de celles-ci, nous proposons un modèle d'objet volumique déformable capable d'adapter (sous une certaine tolérance) son coût de calcul à un niveau de performance imposé.LILLE1-BU (590092102) / SudocSudocFranceF

Tracking ultrafast solid-state dynamics using high harmonic spectroscopy

International audienceWe establish time-resolved high harmonic generation (tr-HHG) as a powerful spectroscopy method for tracking photoinduced dynamics in strongly correlated materials through a detailed investigation of the insulatorto-metal phase transitions in vanadium dioxide. We benchmark the technique by comparing our measurements to established momentum-resolved ultrafast electron diffraction, and theoretical density functional calculations. Tr-HHG allows distinguishing of individual dynamic channels, including a transition to a thermodynamically hidden phase. In addition, the HHG yield is shown to be modulated at a frequency characteristic of a coherent phonon of the equilibrium monoclinic phase over a wide range of excitation fluences. These results demonstrate that tr-HHG is capable of tracking complex dynamics in solids through its sensitivity to the band structure