A multiagent urban traffic simulation Part I: dealing with the ordinary

We describe in this article a multiagent urban traffic simulation, as we believe individual-based modeling is necessary to encompass the complex influence the actions of an individual vehicle can have on the overall flow of vehicles. We first describe how we build a graph description of the network from purely geometric data, ESRI shapefiles. We then explain how we include traffic related data to this graph. We go on after that with the model of the vehicle agents: origin and destination, driving behavior, multiple lanes, crossroads, and interactions with the other vehicles in day-to-day, ?ordinary? traffic. We conclude with the presentation of the resulting simulation of this model on the Rouen agglomeration

From theory to modelling : urban systems as complex systems

The question of complexity and its increasing application to social sciences is challenging the modelling of spatial systems. New concepts and new methods have been proposed and invite to reformulate classical modelling frames. This approach is demanding to open a better informed dialogue between the disciplines which supply models and tools and those where the existing knowledge is reformulated inside this new frame. Actually, creating an « artificial geography » is not straightforward. It is rather easy to translate urban theories within the paradigm of complex systems, but their modelling, for instance by using multi-agents systems, still raises many conceptual and practical difficulties. We underline here some problems in defining significant urban entities and exploring the evolution of their spatial relationships over time. We briefly present which options have been selected for developing the SIMPOP2 model which is conceived for simulating the evolution of systems of cities over long periods of time.La modélisation des systèmes spatiaux se confronte aux théories de la complexité et à leurs applications en sciences sociales. De nouveaux concepts et de nouvelles méthodes sont proposés, qui invitent à reformuler les modèles classiques. Cette démarche suppose d'ouvrir un dialogue mieux informé entre les disciplines qui offrent les modèles et les outils et celles qui tentent de reformuler leurs connaissances dans ce nouveau cadre. En effet, la création d'une « géographie artificielle » ne va pas de soi. S'il est relativement aisé de traduire les théories urbaines en termes de systèmes complexes, leur modélisation, par exemple au moyen de systèmes multi-agents, soulève encore de nombreuses difficultés conceptuelles et pratiques. Nous insistons notamment sur la définition des entités urbaines et sur les variations de leurs relations dans l'espace au cours du temps. Nous présentons enfin rapidement les principales options retenues pour le modèle SIMPOP2 conçu pour simuler le devenir des systèmes de villes dans la longue durée

A multiagent urban traffic simulation. Part II: dealing with the extraordinary

In Probabilistic Risk Management, risk is characterized by two quantities: the magnitude (or severity) of the adverse consequences that can potentially result from the given activity or action, and by the likelihood of occurrence of the given adverse consequences. But a risk seldom exists in isolation: chain of consequences must be examined, as the outcome of one risk can increase the likelihood of other risks. Systemic theory must complement classic PRM. Indeed these chains are composed of many different elements, all of which may have a critical importance at many different levels. Furthermore, when urban catastrophes are envisioned, space and time constraints are key determinants of the workings and dynamics of these chains of catastrophes: models must include a correct spatial topology of the studied risk. Finally, literature insists on the importance small events can have on the risk on a greater scale: urban risks management models belong to self-organized criticality theory. We chose multiagent systems to incorporate this property in our model: the behavior of an agent can transform the dynamics of important groups of them

Massive population evacuation in an urban context

International audienceIncreasing urban sprawl all over the world leads to an increase of vulnerabilities, as greater numbers of goods and people are exposed to hazards, both natural (flood, quakes, fires, tsunami, epidemic) and industrial (factories, plants). Population evacuation features amongst the tools political managers can use to mitigate these risks. When evacuations are decided, managers must strike a fine balance between displacing all the people needed to avoid injuries and fatalities, and not evacuating people that would finally not be struck by the hazard. Evacuated populations convoys must furthermore not lead to a sub-crisis where they become new vulnerabilities, or through disorder and density prevent the management of other vulnerabilities. There is regretfully a scarcity of tools to help risks manager make this kind of decision. We present here our works on such tools. Most risk management policies focus on a planar, continuous conception of space. Seveso Directives for example use different radius around the hazard center, a plant for example, to find which housings and business will be affected at which degree. We described in our presentation for UrbanNet 2013 how this approach was found lacking for handling road networks, both as vulnerabilities of the direct hazard, and as the means for a successful crisis management. In order to overcome this obstacle we proposed a city-wide agent based simulation called MOSAIIC to model the car traffic, both in normal and extraordinary situations. In MOSAIIC each driver is capable of strategical, tactical and operational planning and decision making. They have a list of destinations they try to reach, and choose a path to get there using their knowledge of the network. They accelerate, brake, change ways depending on their surroundings and personality. They choose alternative solutions if trapped in traffic jams of when facing a road networks altered from their initial knowledge. In this follow-up article we would like to discuss the data and its analysis we used to calibrate and validate simulations built with MOSAIIC to study theoretical all-car evacuation of the city of Rouen. Furthermore, since MOSAIIC, we started a new project, ESCAPE (Exploring by Simulation Cities Awareness on Population Evacuation), which aims at simulating massive evacuation

Harnessing a versatile robust lactonase for biotechnological applications

Extremozymes have gained considerable interest as they could meet industrial requirements. Among these, SsoPox is a hyperthermostable enzyme isolated from the archaeon Sulfolobus solfataricus1. This enzyme is a lactonase catalyzing the hydrolysis of acyl-homoserine lactones; these molecules are involved in Gram-negative bacterial communication referred to as quorum sensing2. SsoPox exhibits promiscuous phosphotriesterase activity for the degradation of organophosphorous chemicals including insecticides and chemical warfare agents3. Owing to its bi-functional catalytic abilities as well as its intrinsic stability, SsoPox is appealing for many applications, having potential uses in the agriculture, defense, food and health industries. This enzyme have been rationally engineered and highly improved lactonase and phosphotriesterase variants were isolated4. Their biotechnological properties were investigated and their resistance against diverse process-like and operating conditions such as heat resistance, contact with organic solvents, sterilization, storage and immobilization were underlined5. Lactonase improved variants were shown to drastically reduce virulence and biofilm formation in clinical isolates of Pseudomonas aeruginosa and to decrease mortality in rat pneumonia model6,7. The antibiofilm capacity of the enzyme was also proved to be of outmost interest for antifouling applications. Enhanced phosphotriesterase variants were shown to efficiently decontaminate a broad panel of organophosphorus insecticides and were successfully incorporated into filtration devices for bioremediation purposes8. The degradation products generated through enzyme hydrolysis drastically reduced toxicity and increased regeneration capacity in planarian, an original Plathelmintes model. Regarding their tremendous stability these variants are currently used to develop antibacterial medical devices, antifouling paintings and insecticide bioremediation tools. 1. Elias, M. et al. Structural Basis for Natural Lactonase and Promiscuous Phosphotriesterase Activities. J. Mol. Biol. 379, 1017–1028 (2008). 2. Bzdrenga, J. et al. Biotechnological applications of quorum quenching enzymes. Chem. Biol. Interact. (2016). doi:10.1016/j.cbi.2016.05.028 3. Jacquet, P. et al. Current and emerging strategies for organophosphate decontamination: special focus on hyperstable enzymes. Environ. Sci. Pollut. Res. 1–19 (2016). doi:10.1007/s11356-016-6143-1 4. Hiblot, J., Gotthard, G., Elias, M. & Chabriere, E. Differential Active Site Loop Conformations Mediate Promiscuous Activities in the Lactonase SsoPox. PLoS ONE 8, e75272 (2013). 5. Rémy, B. et al. Harnessing hyperthermostable lactonase from Sulfolobus solfataricus for biotechnological applications. Sci. Rep. 6, (2016). 6. Guendouze, A. et al. Effect of quorum quenching lactonase in clinical isolates of Pseudomonas aeruginosa and comparison with quorum sensing inhibitors. Front. Microbiol. 8, (2017). 7. Hraiech, S. et al. Inhaled Lactonase Reduces Pseudomonas aeruginosa Quorum Sensing and Mortality in Rat Pneumonia. PLoS ONE 9, e107125 (2014). 8. Hiblot, J., Gotthard, G., Chabriere, E. & Elias, M. Characterisation of the organophosphate hydrolase catalytic activity of SsoPox. Sci. Rep. 2, (2012)

Etudes sur le mobilier Boulle, l'ébéniste de Louis XIV : quelques problèmes d'interfaces

National audienceDans le cadre d'un programme mis en place par le musée du Louvre, département des objets d'art, et le C2RMF, autour de l'étude et de la restauration des mobiliers attribués à l'atelier d'André-Charles Boulle ou à ses successeurs, il a été dégagé plusieurs problèmes concernant les marqueteries métalliques et les ornements en bronze doré. Cette communication traite en premier lieu de la compréhension de la mauvaise tenue au vieillissement des collages des pièces de marqueterie en laitons en contradiction avec la bonne tenue des pièces en étain voisines. Les propriétés mécaniques des assemblages laiton/colle/bois et étain/colle/bois utilisant la colle animale, notamment de poisson, ont été étudiées et la rupture prématurée de ces assemblages a pu être expliquée en tenant compte de la rhéologie des composants. En second lieu sont étudiées les dorures des ornements en bronze doré, grâce à l'utilisation des analyses par faisceaux d'ions. Les premiers résultats donnent une idée du procédé de dorure à l'amalgame de mercure utilisé et des épaisseurs d'or appliquées, ainsi que du procédé électrolytique utilisé pour les pièces restaurées

: Recueil de fiches pédagogiques du réseau MAPS

DoctoralLe réseau thématique MAPS «Modélisation multi-Agent appliquée aux Phénomènes Spatialisés » propose depuis 2009 des évènements scientifiques ayant pour but de diffuser les pratiques de modélisations multi-agents au sein des Sciences de l’Homme et de la Société (SHS). Ce collectif pluridisciplinaire de chercheurs, d’enseignants-chercheurs et de doctorants est labellisé en tant que ≪ réseau thématique » par le Réseau National des Systèmes Complexes (GIS RNSC) et bénéficie du soutien du CNRS au titre de la Formation Permanente. Depuis 2009, plusieurs modèles ont été développés au cours d'événements MAPS. Ces modèles ont fait l'objet de fiches pédagogiques détaillées destinées aux communautés éducatives et universitaires et en particulier aux enseignants qui souhaiteraient faire découvrir la modélisation à leurs étudiants, mais aussi à ceux qui envisagent d’approfondir certains aspects avec un public plus averti. Elles sont également destinées à tous les curieux qui souhaiteraient découvrir ce que la modélisation apporte aux SHS, du point de vue heuristique et du point de vue opérationnel. Enfin, elles sont aussi des supports pour toutes les personnes qui souhaiteraient diffuser les réflexions scientifiques sur la modélisation et la simulation qui ont présidé à la rédaction de ces fiches

Du complexe à la complexité : Le retour de l'individu dans les modèles géographiques

National audienceGeographer studies the consequences of the human actions on the production and the organization of space, and in return, the effects of these achievements on the behaviors of these actors. Actions and events associated to individual actors (people, households, firm etc) are partly related to their characteristics, to the environmental context and to the interactions with the other actors. These actions and events are also related to their behaviors, which are the result of their intentions, their duties and projects which they work out (storage capacities, development of strategy, representation). These actions and events are finally subjected to a whole of constraints and risks which form part of a space-time context. It is thus necessary to take into account on the one hand the freedom of the actors, even deployed within the framework of a certain number of constraints, and on the other hand their intentionnality to construct a formalization of this complexity in space and time.Le géographe étudie les conséquences des actions humaines sur la production et l’organisation de l’espace, et en retour, les effets de ces réalisations sur les comportements de ces acteurs. Les actions et évènements que l’on associe aux acteurs individuels (personnes, ménages, entreprises etc.) sont en partie liés à leurs caractéristiques, au contexte environnemental et aux interactions avec les autres acteurs. Ces actions et évènements sont également liés à leurs comportements, qui sont le résultat de leurs intentions, de leurs devoirs et des projets qu’ils élaborent (capacités de mémorisation, de développement de stratégie, de représentation). Ces actions et évènements sont enfin soumis à un ensemble de contraintes et d’aléas qui s’insèrent dans un contexte spatio-temporel. Il est donc nécessaire de prendre en compte d’une part la liberté des acteurs, même déployée dans le cadre d'un certain nombre de contraintes, et d’autre part leur intentionnalité pour élaborer une formalisation de cette complexité socio-spatiale

Apports de la simulation multi-agents à l’étude des processus de diffusion

This paper presents the main contributions of an agent-based approach for modelling and simulating the processes of diffusion in geographical space. This approach is compared with the macro modelling traditionally employed to describe such phenomenons. The logistic model is thus presented as representative of this category of model. The agent-based models represent a possible alternative to a macroscopic approach of the processes of diffusion. Related to the theories of self-organization, it is assumed that the phenomena observed on a certain level are the result of the many interactions which occur on one or more lower levels. As a simulation tool predisposed to the analysis of such a dynamic, the multi-agent systems are briefly presented. This paper ends with a brief example of application, the modelling and the simulation of the diffusion of an agricultural innovation model (Hägerstrand's model revisited)