Introduction of a combination vector to optimise the interpolation of numerical phantoms

International audiencePhantoms are 3-dimensional (3D) numerical representations of the contours of organs in the human body. The quality of the dosimetric reports established when accidental overexposures to radiation occur is highly dependent on the phantom's reliability with respect to the subject. EquiVox is a Case-Based Reasoning platform which proposes an interpolation of the 3D Lung Contours (3DLC) of subjects during its adaptation phase. This interpolation is conducted by an Artificial Neural Network (ANN) trained to learn how to interpolate the 3DLC of a Learning Set (LS). ANN is a well-suited tool when known results are numerous. Since the cardinality of our learning set is restrained, the imperfections of each 3DLC have a great impact on interpolations. Thus, we explored the possibility of ignoring some of the 3DLC of LS via implementation of a new learning algorithm which associated Combination Vectors (CV) to LS. The results proved that this method could optimise interpolation accuracy. Furthermore, this study highlights the fact that some of the 3DLC were harmful for some interpolations whereas they increased the accuracy of others

An Oriented Convergent Mutation Operator for Solving a Scalable Convergent Demand Responsive Transport Problem

International audienceThis paper presents a method for solving the convergence demand responsive transport problem, by using a stochastic approach based on a steady state genetic algorithm for enumerating a set of optimizing sprawling spanning trees, which constitute the best solutions to this problem. Specifically designed to speed up the convergence to optimal solutions, we introduce an oriented convergent mutation operator, allowing multi-objective considerations. So this solution lays the first stakes for considering real-time solving of such a problem. Led by computer science and geography laboratories, this study is provided with a set of experimental results evaluating the approach

An Agent-Based Framework for Urban Mobility Simulation

International audienceMobility study is composed of many research areas which one interests us: urban mobility. In the literature, urban mobilities are represented by analytical techniques like stochastic laws or they are defined by simulation tools like Multi-Agents Systems (MAS). The goal of our work is to define citizen behaviour in order to observe population dynamics by a simulation. This strategy is facilitated by a meta-model and a toolkit which are used with a particular method. The latter begins by a conceptual representation of each mobile and finishes by a mobility simulator. This paper aims at describing the mobility simulation toolkit. Thanks to this framework, mobility simulator development is sim- plified. It allows us to create distributed applications which are based on MAS

Comparison of three algorithms for solving the convergent demand responsive transportation problem

International audienceLed by computer science and geography laboratories, this paper presents three algorithms for solving the Convergent Demand Responsive Transport Problem (CDRTP). Two of them are exact: the first one is based on a dynamic programming algorithm to enumerate exhaustively the sprawling spanning trees and the second one is based on a depth first search algorithm. The third one is stochastic and uses a steady state genetic algorithm. These approaches address the problems of scalability and flexibility, are compared and discussed

iPedagogique : une application d'apprentissage multi-usages intégrant une pédagogie de projets tutorés basée sur la synchronisation de fragments de procédés coopératifs.

International audienceL'enseignement d'unités de valeurs scientifiques ou techniques est largement fondé sur l'acquisition de connaissances conceptuelles et la validation d'un savoir-faire. Au cours d'une formation, l'apprenant et l'enseignant doivent être efficaces tant du point de vue quantitatif que qualitatif, tout spécialement en surmontant des difficultés organisationnelles, en introduisant (ou acquérant selon) des compétences implicites à la conduite ou la gestion de projet, en bénéficiant d'une aide à la synchronisation. Nous présentons les grandes lignes d'une application auteur en expérimentation dans une école d'ingénieurs généralistes et dans deux formations Multimédia (IUT, IUP). Tout particulièrement nous rapportons l'intégration expérimentale réussie de la pédagogie par projets. Nous présentons un méta modèle de procédés coopératifs de gestion de projet d'une entreprise pédagogique éphémère. Nous l'illustrons expérimentalement et nous poursuivons l'étude par la présentation des prémisses d'un système d'aide multi-usages

An Agent Based Framework for Urban Mobility Simulation

16 route de Gra

Etude Comparative D'algorithmes D"equilibrage De Charge Sur Multicalculateurs

Introduction Les multicalculateurs proposent une alternative int'eressante pour augmenter la puissance des ordinateurs. Mais, l'augmentation du nombre de noeuds impose un travail plus important pour l'allocation des processeurs. Il devient n'ecessaire aux nouveaux syst`emes d'exploitation de prendre le relais des utilisateurs pour la gestion de la ressource d'ex'ecution. L"equilibrage de charge, en permettant la prise en charge des applications `a grains moyens ou gros, favorise la g'en'eralisation des multicalculateurs. L'objectif de notre travail est de faire apparaitre l'int'eret de l"equilibrage de charge, et de comparer diff'erents algorithmes de la litt'erature, en montrant leurs sp'ecificit'es. Dans cet article nous pr'esentons les r'esultats que nous obtenons `a l'issue de l'implantation de trois algorithmes sur un multicalculateur `a base de transputers, au dessus du syst`eme Chorus/MiX [2][1]. Dans un premier temps, nous introduisons les principes de l"equilibrage d

An iterative precision vector to optimise the CBR adaptation of EquiVox

International audienceThe case-based reasoning (CBR) approach consists in retrieving solutions from similar past problems and adapting them to new ones. Interpolation tools can easily be used as adaptation tools in CBR systems. The accuracies of interpolated results depend on the set of known solved problems with which the interpolation tools have previously been trained. To be sufficiently accurate, an interpolation tool must be trained with a large number of known cases. However, CBR systems are also relevant if the number of known cases is restricted. In addition, the training of interpolation tools is generally seen by users as a black box. This paper presents a generic method to optimise CBR adaptations driven by trained interpolation tools and also takes into account remarks made by users about known solution accuracy. This method was applied to the CBR system called EquiVox which retrieves, reuses (interpolates), revises and retains three-dimensional numerical representations of organ contours and thus enhances its own performance