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This thesis is to develop a decision support system for tracking mobile targets with a network of wireless sensors deployed in an uncertain environment. This will be achieved by developing optimization methods for exploiting these... more
This thesis is to develop a decision support system for tracking mobile targets with a network of wireless sensors deployed in an uncertain environment. This will be achieved by developing optimization methods for exploiting these networks, and dynamic online algorithms to deal with large amplitude uncertainties, like sensor failures and targets unexpected trajectories. The thesis is jointly supervised by Prof. André Rossi, LERIA lab, University of Angers, France, and by Prof. Marc Sevaux, Lab-STICC, University of South Brittany, Lorient, France.
Un reseau de capteurs sans fil est constitue de capteurs repartis aleatoirement sur une region etendue souvent rendue difficile d’acces et sans infrastructure a cause de catastrophes naturelles ou d’operations militaires. Il est donc... more
Un reseau de capteurs sans fil est constitue de capteurs repartis aleatoirement sur une region etendue souvent rendue difficile d’acces et sans infrastructure a cause de catastrophes naturelles ou d’operations militaires. Il est donc impossible de recharger la batterie de ces capteurs, qui limitent alors la duree de vie du reseau, c’est-a-dire la periode de temps pendant laquelle le reseau peut accomplir sa mission. Les types de capteurs et leurs domaines d’application sont varies, nous considerons le suivi de cibles mobiles (avions, trains, vehicules terrestres, etc) dont la trajectoire spatiale est connue, mais la vitesse seulement estimee. L’objectif du reseau est de garantir a tout moment la surveillance des cibles, ainsi que la transmission de l’ensemble des donnees recoltees a une station de base.
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Le developpement de la livraison en milieu urbain engendre une mutation profonde des metiers de la logistique et les usages evoluent rapidement [2]. Les attentes des consommateurs forcent la reduction des delais de livraison et reclament... more
Le developpement de la livraison en milieu urbain engendre une mutation profonde des metiers de la logistique et les usages evoluent rapidement [2]. Les attentes des consommateurs forcent la reduction des delais de livraison et reclament en parallele l’augmentation du suivi de celles-ci. La legislation subit elle aussi une mutation rapide afin de limiter les derives et les abus induits par ces changements de comportement. Les poids lourds sont exclus des centres-villes et les vehicules legers polluants, en terme d’emissions de gaz a effet de serre, de particules ou de pollution sonore voient leur acces aux zones denses restreinte. Egalement, l’encombrement des axes routiers menent les acteurs de la logistique a revoir integralement le processus de livraison. Les entreprises proposant des demarches alternatives et ecoresponsables fleurissent. Les politiques d’exclusion des poids lourds s’accompagnent d’amenagement d’emplacements de stationnement dedies en milieu peri-urbain. Ces plat...
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A wireless sensor network (WSN) is constituted of spatially distributed autonomous sensors dedicated to monitor physical or environmental conditions, such as temperature, sound, pressure, toxic gaz... The development of wireless sensor... more
A wireless sensor network (WSN) is constituted of spatially distributed autonomous sensors dedicated to monitor physical or environmental conditions, such as temperature, sound, pressure, toxic gaz... The development of wireless sensor networks was motivated by military applications such as battlefield surveillance or by industrial applications, such as process monitoring in production industry, health monitoring, and for a large part, monitoring in hostile environment (e.g. highly polluted places). One of the key issues of a WSN is to maintain its activity over the largest possible time period, the lifetime. This survey concerns a very challenging category of problems where a set of targets should be monitored over time by the sensors (having a limited level of energy) that can be activated individually. The goal is to maximize the lifetime of the network by activating simultaneously subgroups of sensors covering the targets for a specific duration. Several variants of the original...
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ISBN 2-212-11385-
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Resoudre des problemes d'optimisation est un point cle dans l'amelioration constante de la productivite des entreprises. Quand les methodes traditionnelles echouent, il devient alors naturel de se tourner vers des techniques de... more
Resoudre des problemes d'optimisation est un point cle dans l'amelioration constante de la productivite des entreprises. Quand les methodes traditionnelles echouent, il devient alors naturel de se tourner vers des techniques de resolution approchee. Les metaheuristiques jouent, aujourd'hui, un role primordial dans la resolution des problemes d'optimisation. Ces techniques sont devenues, en quelques annees, des outils incoutournables et performants. Dans cette synthese, nous presentons un panorama des metaheuristiques classiques (methodes de descente, recuit simule, recherche tabou, algorithmes genetiques), de certaines moins connues (recherche a voisinages variables, GRASP, iterated local search, guided local search, colonies de fourmis) et de techniques avancees (algorithmes memetiques, scatter search, GA|PM). Pour toutes ces methodes, nous analysons les facteurs d'intensification et de diversification presents, les particularites de chacune d'elle et notre ...
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The paper considers the hybrid flow-shop scheduling problem with multiprocessor tasks. Motivated by the computational complexity of the problem, we propose a memetic algorithm for this problem in the paper. We first describe the... more
The paper considers the hybrid flow-shop scheduling problem with multiprocessor tasks. Motivated by the computational complexity of the problem, we propose a memetic algorithm for this problem in the paper. We first describe the implementation details of a genetic algorithm, which is used in the memetic algorithm. We then propose a constraint programming based branch-and-bound algorithm to be employed as
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ABSTRACT
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With almost 160.000 employees worldwide and a 2006 turnover of over 10 billion US $, TNT is one of the largest courier services companies in the world. Its main operations consist of collecting parcels from customers, and redistributing... more
With almost 160.000 employees worldwide and a 2006 turnover of over 10 billion US $, TNT is one of the largest courier services companies in the world. Its main operations consist of collecting parcels from customers, and redistributing these parcels to a destination indicated by the customer. In this talk, we discuss several opportunities for operations research, and especially vehicle routing, to assist in these complex operations. We also discuss a heuristic approach that we developed for a multiobjective routing problem at TNT.
... Thus, Xiaobu et al. provide innovative solutions for challenging real-world problems. ... The authors point out that a method-ological fusion can be done, not only on the algorithmic level, but also on the systems level. They use a... more
... Thus, Xiaobu et al. provide innovative solutions for challenging real-world problems. ... The authors point out that a method-ological fusion can be done, not only on the algorithmic level, but also on the systems level. They use a manufacturing system to illustrate their results. ...
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The solution of the biobjective IRP is rather challenging, even for metaheuristics. We are still lacking a profound understanding of appropriate solution representations and effective neighborhood structures. Clearly, both the delivery... more
The solution of the biobjective IRP is rather challenging, even for metaheuristics. We are still lacking a profound understanding of appropriate solution representations and effective neighborhood structures. Clearly, both the delivery volumes and the routing aspects of the alternatives need to be reflected in an encoding, and must be modified when searching by means of local search. Our work contributes to the better understanding of such solution representations. On the basis of an experimental investigation, the advantages and drawbacks of two encodings are studied and compared.
ABSTRACT This paper addresses resolution of a robust scheduling problem arising at the French railways company. The objective is to reduce the immobilization of trains during the maintenance operations. The processing times of operations... more
ABSTRACT This paper addresses resolution of a robust scheduling problem arising at the French railways company. The objective is to reduce the immobilization of trains during the maintenance operations. The processing times of operations are submitted to hazards and the objective is to minimize both the total completion time (emphi.e. the makespan) and to limit the random event consequences on solution quality. Solutions must be robust when facing some variations of processing times. Due to periodic modifications in the composition of trains a computer aided design system is required to avoid periodic manual planning computation. This system must provide machine sequence of operations, makespan evaluation and an evaluation of the processing time variation consequences. The purpose of this paper is to present a dedicated genetic algorithm fo robust solutions computation.
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