Apports des rôles à la construction et à l'expérimentation de modèles multi-agents pour la gestion de ressources renouvelables

Le formalisme Agent-Groupe-Rôle propose de recourir à des abstractions organisationnelles (groupes et rôles) pour concevoir des systèmes multi-agents (SMA) selon une approche sociale, ou organisation centrée. Plutôt que de se concentrer sur les activités des agents, le concepteur d'un système AGR se concentre sur la structuration de ces activités. Dans le champ de la gestion de ressources renouvelables, les modélisateurs doivent apréhender des systèmes complexes où des dynamiques sociales et physiques se déroulent dans différents niveaux d'organisation entrelacés. Le formalisme AGR permet de représenter explicitement ces niveaux d'organisation et leurs articulations. Cette communication se concentre sur l'apport des rôles à la modélisation multi-agent pour la gestion de ressources renouvelables. Après avoir discuté du concept de rôle en informatique, les différents types de rôles introduits dans le modèle AGR d'une application de gestion d'étiage dans la vallée de la Drôme sont décrits. La question de la composition des rôles et la manière dont elle est résolué dans le cas de la Drôme sera examiné. Sur la base de cet exemple, un bilan des apports et limites de l'utilisation des rôles en termes d'expressivité et de modularité des modèles est dressé en conclusion / The Agent-Group-Role-Formalism has been introduced in the field of computer science as a possible instantiation of an organization-centred approach of multi-agent systems (MAS). Using groups and roles in MAS design, the AGR formalism brings the focus from agents activities description to agents activities structuring. In the field of agent-based modelling (ABM) for renewable resources management, modellers are facing complex systems where social and physical dynamics take place within various interwoven levels of organization. Using AGR formalism is a way to explicitly represent the various levels of organization of a system and their articulations. This paper focuses on the use of roles in ABM for renewable resources management. The concept of role in computer science is first discussed. Then, different types of roles arising from an application case in the southern France Drôme river valley are described. The issue of roles composition and how it is resolved in the Drôme model is examined. The paper concludes on the contributions and on the limits that using roles brings to ABM modularity and expressivit

Recovery and reuse of discontinuous carbon fibres by solvolysis: Realignment and properties of remanufactured materials

Discontinuous carbon fibre tows were recovered after solvolysis of an aeronautic type composite made with RTM6 epoxy resin. A Sohxlet extraction method was used to quantify the organic residue on the fibre tows and showed that less than 3 wt% was remaining on the surface. The recovered tows were therefore reused directly to manufacture a plate with randomly distributed carbon fibres and then three plates with realigned carbon fibres. The latter were then characterised and tested and the results obtained were compared to the material manufactured using the same type of virgin fibres by the same method. The materials made from recycled carbon fibres showed very good properties in comparison to the virgin fibre material, despite the presence of flaws such as quality of the fibre surface after solvolysis, alignment and voids). This is the first time in the open literature that carbon fibres recovered from solvolysis were reused in this way together with characterisation of the resulting materials

Species-specific responses to landscape fragmentation: implications for management strategies

Habitat fragmentation affects the integrity of many species, but little is known about species-specific sensitivity to fragmentation. Here, we compared the genetic structure of four freshwater fish species differing in their body size (Leuciscus cephalus; Leuciscus leuciscus; Gobio gobio and Phoxinus phoxinus) between a fragmented and a continuous landscape. We tested if, overall, fragmentation affected the genetic structure of these fish species, and if these species differed in their sensitivity to fragmentation. Fragmentation negatively affected the genetic structure of these species. Indeed, irrespective of the species identity, allelic richness and heterozygosity were lower, and population divergence was higher in the fragmented than in the continuous landscape. This response to fragmentation was highly species-specific, with the smallest fish species (P. phoxinus) being slightly affected by fragmentation. On the contrary, fish species of intermediate body size (L. leuciscus and G. gobio) were highly affected, whereas the largest fish species (L. cephalus) was intermediately affected by fragmentation. We discuss the relative role of dispersal ability and effective population size on the responses to fragmentation we report here. The weirs studied here are of considerable historical importance. We therefore conclude that restoration programmes will need to consider both this societal context and the biological characteristics of the species sharing this ecosyste

Principes de procédure pénale

Comme l’écrivait le jurisconsulte italien G.D. Pisapia « si vous débarquez dans un pays inconnu et si désirez savoir si, dans ce pays, les libertés civiles sont protégées, demandez à voir son Code de procédure pénale ». La procédure pénale a, assurément, valeur de garanties des droits fondamentaux des justiciables confrontés aux juridictions répressives. Son importance n’est plus à démontrer tant, par une pénalisation croissante des comportements humains, elle s’est s’immiscée dans de nombreuses branches du droit. Devenue une discipline en tant que telle, la procédure pénale mérite, dès lors, une attention toute particulière. Le but du présent ouvrage n’est pas d’être exhaustif mais de synthétiser de manière didactique les grands principes qui sous-tendent la dialectique du procès pénal. Pour ce faire, il se calque sur le déroulement par phases de ce procès. Cet ouvrage offre aux lecteurs une vision d’ensemble de la procédure pénale. Il se veut un outil pédagogique destiné aux étudiants en droit mais encore une source d’inspiration pour les praticiens avertis ou occasionnels des juridictions répressives

La fratrie comme ressource: Le rôle des aînés dans les parcours scolaires des enfants de familles nombreuses

De nombreuses enquêtes statistiques montrent que le fait de grandir au sein d'une famille nombreuse a un effet négatif sur les devenirs scolaires. Une enquête par entretiens auprès d'une vingtaine de ces familles nous permet de mettre en évidence les conditions dans lesquelles la taille de la fratrie affecte les parcours scolaires, mais aussi comment la fratrie peut, a contrario, devenir une ressource, en particulier dans les familles les plus démunies en capitaux culturels. L'article propose ainsi d'analyser les modalités et les effets de l'accompagnement scolaire et culturel assuré par des aînés de familles nombreuses. S'il est possible d'observer, sous certaines conditions, des effets scolaires bénéfiques pour les cadets, on peut noter également des effets " en retour " de cette intervention fraternelle sur la scolarité des aînés eux-mêmes et sur les pratiques éducatives des parents

Multi-Scale Anisotropic Mesh Adaptation for Time-Dependent Problems

This paper deals with anisotropic mesh adaptation applied to unsteady inviscid CFD simulations. Anisotropic metric-based mesh adaptation is an efficient strategy to reduce the extensive CPU time currently required by time-dependent simulations from the perspective of performing this kind of computations on a daily basis in an industrial context. In this work, we detail the time-accurate extension of multi-scale anisotropic mesh adaptation for steady flows, i.e., a control of the interpolation error in Lp norm, to unsteady flows based on a space-time error analysis and an enhanced version of the fixed-point algorithm. We also show that each stage - remeshing, metric field computation, solution transfer, and flow solution - is important to design an efficient time-accurate anisotropic mesh adaptation process. The parallelization of the whole mesh adaptation platform is also discussed. The efficiency of the approach is emphasized on three-dimensional problems with convergence analysis and CPU data

Time-accurate anisotropic mesh adaptation for three-dimensional time-dependent problems with body-fitted moving geometries

International audienceAnisotropic metric-based mesh adaptation has proved its efficiency to reduce the CPU time of steady and unsteady simulations while improving their accuracy. However, its extension to time-dependent problems with body-fitted moving geometries is far from straightforward. This paper establishes a well-founded framework for multiscale mesh adaptation of unsteady problems with moving boundaries. This framework is based on a novel space–time analysis of the interpolation error, within the continuous mesh theory. An optimal metric field, called ALE metric field, is derived, which takes into account the movement of the mesh during the adaptation. Based on this analysis, the global fixed-point adaptation algorithm for time-dependent simulations is extended to moving boundary problems, within the range of body-fitted moving meshes and ALE simulations. Finally, three dimensional adaptive simulations with moving boundaries are presented to validate the proposed approach