Final Report of the ModSysC2020 Working Group - Data, Models and Theories for Complex Systems: new challenges and opportunities

Final Report of the ModSysC2020 Working Group at University Montpellier 2At University Montpellier 2, the modeling and simulation of complex systems has been identified as a major scientific challenge and one of the priority axes in interdisciplinary research, with major potential impact on training, economy and society. Many research groups and laboratories in Montpellier are already working in that direction, but typically in isolation within their own scientific discipline. Several local actions have been initiated in order to structure the scientific community with interdisciplinary projects, but with little coordination among the actions. The goal of the ModSysC2020 (modeling and simulation of complex systems in 2020) working group was to analyze the local situation (forces and weaknesses, current projects), identify the critical research directions and propose concrete actions in terms of research projects, equipment facilities, human resources and training to be encouraged. To guide this perspective, we decomposed the scientific challenge into four main themes, for which there is strong background in Montpellier: (1) modeling and simulation of complex systems; (2) algorithms and computing; (3) scientific data management; (4) production, storage and archiving of data from the observation of the natural and biological media. In this report, for each theme, we introduce the context and motivations, analyze the situation in Montpellier, identify research directions and propose specific actions in terms of interdisciplinary research projects and training. We also provide an analysis of the socio-economical aspects of modeling and simulation through use cases in various domains such as life science and healthcare, environmental science and energy. Finally, we discuss the importance of revisiting students training in fundamental domains such as modeling, computer programming and database which are typically taught too late, in specialized masters

Activists forever ? Long-Term Impacts of Political Activism

Activists Forever examines the personal consequences of activism, a topic that had passed under the radar of research, and triggers now a renewed attention among scholars and the broader audience of people interested in social movements. It focusses on the impact of social movements on the life-course of movement participants. While revolution may finally appear as an unreachable goal, the impact of activists on social change remains indisputable. In the workplace, civil society or private relations they experienced new behaviors that spreaded among the population in general. The volume makes a significant contribution to research on social movement outcomes by achieving three aims: theoretically, by showing the importance of hitherto undervalued topics in the study of social movements outcomes; methodologically, by expanding the scientific boundaries of this research field through an interdisciplinary approach and new methods of analysis; and substantially, by providing new empirical evidence about social movement outcomes worldwide

Sous-structuration de systèmes thermiques par modes de branche

Cette étude concerne la simulation de systèmes thermiques comportant plusieurs domaines à l aide d une méthode d ordre réduit adaptée au mono-corps. Les modèles modaux réduits sont construits à partir de modes de branche. Ceux-ci sont déterminés à l aide d un modèle détaillé et permettent la prise en compte de non-linéarités. La réduction est effectuée par la technique de l amalgame modal découplé qui permet de façon automatique et immédiate d obtenir une base réduite qui ne comporte qu un faible nombre de modes à partir de la base initiale. Le couplage entre les différents domaines s effectue par l intermédiaire d une résistance thermique de contact. On montre la nécessité de faire intervenir un terme supplémentaire de pénalisation de saut de flux qui vient améliorer les résultats. Les simulations numériques effectuées sur des cas tests (microprocesseur et radiateur en 2D, bloc métallique avec cartouches chauffantes en 3D) montrent la pertinence de la méthode.This study concerns the simulation of thermal systems with multiple fields with a reduced-order method suited to a single body. Reduced models are constructed from modal branch eigenmodes. They are determined using a detailed model and allow the inclusion of non-linearities. The reduction is carried out by the simplified amalgam method which allows an automatic and immediate way to obtain a reduced basis which contains only a small number of modes from the original basis. The coupling between the different areas is carried out through a thermal contact resistance. It shows the need to involve an additional flux jump penalty term to improve the results. The numerical simulations carried out on test cases (microprocessor and radiator in 2D, metal block with hot cartridges in 3D) show the relevance of the method.EVRY-Bib. électronique (912289901) / SudocSudocFranceF

Developing a method for coupling branch modal models

International audienceAn original method is proposed to reduce diffusion problem characterized by a thermal contact resistance and non-linear boundary conditions. The method use a substructuring technique in which a branch modal basis is obtained for each subdomain. The amalgam reduction method for each basis leads to a global reduced model. A specific flux jump functional allows to optimize reduction. The numerical test case is an electronic component coupled with a radiator and which follows a thermal regulation. For this case a numerical study is made in order to observe the influence of the flux jump functional. Comparison between the detailed model and the reduced one with optimal parameters gives a gain in computation time of 82 for the same precision

Optimisation de couplage de modèles réduits par fonctionnelle de pénalisation de flux : application à un composant

International audienceNous présentons dans cette étude une technique optimisée de réduction par modes de branche adaptée aux problèmes caractérisés par une résistance thermique de contact entre deux matériaux. Cette méthode fait intervenir une fonction de pénalisation de flux. On montre ainsi dans le cas d'un composant électronique muni d'un radiateur l'importance de cette fonction de pénalisation. Les résultats font apparaître un gain en temps calcul important pour une erreur entre modèles réduits et de référence tout à fait satisfaisante

Modèle réduit pour une équation d'advection-diffusion par modes de branche

International audienceNous proposons ici une méthode originale permettant de réduire un problème d'advection diffusion dans un solide en rotation, dans lequel les paramètres peuvent être instationnaires et non linéaires. L'application traitée correspond à un disque en rotation rapide à vitesse variable, subissant des sollicitations volumiques et surfaciques instationnaires. La comparaison entre modèle complet et modèle réduit fait apparaître un gain en temps de calcul de l'ordre de 150, pour une erreur maximum inférieure à 10%

Experimental heat flux identification from a braking system

International audienceThis article presents the branch eigenmodes reduction method (BERM) applied to the identification of the heat flux dissipated during the friction between a disc rotating at variable speed and two brake pads. Temperature measurements used to identify fluxes in the disc and in the pad come from experimental data. One of the method's strength lies in its ability to greatly reduce the dimension of the numerical problem, while maintaining a satisfying precision on the whole computation domain. The reduction of the model enables us to perform the identification in a time compatible with real-time. The identified heat flux is coherent with the mechanical increase due to friction. Small discrepancies observed at the beginning of the friction sequence can be explained by wea