Gildas Morvan

Imagerie normale et pathologique du système suro-achilléo-plantaire propulseur du pied

Resume L’appareil extenseur du pied est essentiellement forme d’un puissant moteur, le muscle triceps sural muni d’un systeme de transmission particulierement sophistique : l’ensemble tendon calcaneen (ou d’Achille), tuberosite posterieure du calcaneus et aponevrose plantaire, en continuite avec le squelette fibreux du muscle triceps. La connaissance precise de l’anatomie de ce squelette fibreux permet de comprendre la majorite des lesions anatomiques de l’appareil extenseur et ses images pathologiques. Sur cette base, il est possible de scinder les pathologies du systeme suro-achilleo-plantaire en un ensemble de sous-unites precises, avec pour chacune d’elles, une clinique assez typique, une imagerie caracteristique et un traitement reconnu. Le couple radio-echographie suffit au diagnostic et au suivi dans l’immense majorite des cas. Les autres relevent de l’IRM.

Multilevel Agent-Based Modeling of System of Systems

This paper deals with the generic modeling of systems of systems (SoSs) using agent-based modeling. SoSs are large-scale systems, including numerous—possibly heterogeneous—interacting component systems evolving in a dynamic environment. The aim of this paper is to provide generic formalism allowing to represent and control the whole complexity of a SoS using agent-based simulations. In particular, organizational aspects of SoSs are managed with the Agent–Group–Role model. Functional aspects, guiding SoSs to accomplish their global goals, are handled via a functional specification. Multilevel aspects are modeled with the Influence Reaction Model for Multilevel Simulation (IRM4MLS) agent-based meta-model. Models generated using this formalism encompass static and dynamic aspects of SoSs. They consider reorganization of SoSs caused by changes of goals or subsystem capacity. All these elements are illustrated in this paper using a SoS case study of Intelligent Autonomous Vehicles initiated by the Intelligent Transportation for Dynamic Environment (InTraDE) European project to automate the port container logistic.

IRM4MLS: the influence reaction model for multi-level simulation

In this paper, a meta-model called IRM4MLS, that aims to be a generic ground to specify and execute multi-level agent-based models is presented. It relies on the influence/reaction principle and more specifically on IRM4S [13,14]. Simulation models for IRM4MLS are defined. The capabilities and possible extensions of the meta-model are discussed.

A Methodology to Engineer and Validate Dynamic Multi-level Multi-agent Based Simulations

This article proposes a methodology to model and simulate complex systems, based on IRM4MLS, a generic agent-based meta-model able to deal with multi-level systems. This methodology permits the engineering of dynamic multi-level agent-based models, to represent complex systems over several scales and domains of interest. Its goal is to simulate a phenomenon using dynamically the lightest representation to save computer resources without loss of information. This methodology is based on two mechanisms: (1) the activation or deactivation of agents representing different domain parts of the same phenomenon and (2) the aggregation or disaggregation of agents representing the same phenomenon at different scales.

Evidential calibration process of multi-agent based system

Highlights? We present a problem of calibration and validation of multi-agent based simulations. ? Simulation validation consists to measure if the simulation is close to a reality. ? Before the validation, calibration is a process to define the model parameters. ? We employ the belief function to deal imperfect data, used in validation/calibration. ? This global process is illustrated with an application to forensic entomology. Forensic entomology consists, during a criminal investigation, in studying the insects found on a cadaver to estimate the time of death. This is the only technique that can be used for a large post-mortem interval. But, because of the important system complexity, the result given by the expert are imperfect. In this paper, a decision support system (DSS) has been developed to take into account all the ecosystemic parameters and a significant quantity of biological models. The proposed DSS is based on the belief function theory to validate and calibrate agent based simulations. First results of this architecture are presented within the framework of a real forensic examination.

Engineering Hierarchical Complex Systems: An Agent-Based Approach. The Case of Flexible Manufacturing Systems

This chapter introduces a formal model to specify, model and validate hierarchical complex systems described at different levels of analysis. It relies on concepts that have been developed in the multi-agent-based simulation (MABS) literature: level, influence and reaction. One application of such model is the specification of hierarchical complex systems, in which decisional capacities are dynamically adapted at each level with respect to the emergences/constraints paradigm. In the conclusion, we discuss the main perspective of this work: the definition of a generic meta-model for holonic multi-agent systems (HMAS).

State reconstructor for real-time freeway ramp metering

The work presented in this paper aims to solve the problem of isolated ramp metering in the case of unavailable (not measured) traffic state variables (density and mean speed). A state reconstructor is then proposed and a systematic approach is developed for real time freeway ramp metering. The state reconstructor is developed using a second order sliding mode observer, while the control algorithm is based on the concept of differential flatness. Numerical simulations demonstrate the relevance of the provided algorithm for both state reconstructor and control of freeway networks.

Real-time dynamic traffic routing using variable structure control

In this paper, we present a new algorithm to deal with the real-time dynamic traffic routing (DTR) problem using a second order traffic flow model (METANET). We investigate variable structure control (VSC) as a high-speed switched feedback control resulting in sliding mode. The control objective is to minimize the difference of the travel times on alternate routes in a network setting. Accordingly, the congestion could be reduced/eliminated. The relevance of the proposed algorithm is demonstrated via a set of numerical simulations in the case of the same as well as different geometric conditions.

Observation of large-scale multi-agent based simulations

The computational cost of large-scale multi-agent based simulations (MABS) can be extremely important, especially if simulations have to be monitored for validation purposes. In this paper, two methods, based on self-observation and statistical survey theory, are introduced in order to optimize the computation of observations in MABS. An empirical comparison of the computational cost of these methods is performed on a toy problem.

Multi-level agent-based simulations: Four design patterns

Abstract This paper describes four design patterns that aim at systematizing and simplifying the modelling and the implementation of multi-level agent-based simulations. Such simulations are meant to handle entities belonging to different, yet coupled, abstractions or organization levels. The patterns we propose are based on minimal typical situations drawn from the literature. For each pattern, we present use cases, associated data structures and algorithms. For genericity purposes, these patterns rely on a unified description of the capabilities for action and change of the agents. Thus, we propose a precise conceptual and operational framework for the designers of multi-level simulations.