Julien Fondrevelle

Permutation flow shops with exact time lags to minimise maximum lateness

In this paper we investigate the m-machine permutation flow shop scheduling problem where exact time lags are defined between consecutive operations of every job. This generic model can be used for the study and analysis of various real situations that may arise, for instance, in the food-producing, pharmaceutical and steel industries. The objective is to minimise the maximum lateness. We study polynomial special cases and provide a dominance relation. We derive lower and upper bounds that are integrated in a branch-and-bound procedure to solve the problem. Three branching schemes are proposed and compared. We perform a computational analysis to evaluate the efficiency of the developed method.

Job-shop production scheduling with reverse flows

In this paper, we present a modeling approach for the NP-hard scheduling problem Job-shop with reverse flows. This problem is characterized by two flows that cover the same machines but in opposite senses. The objective is to minimize the maximum completion time of the jobs. We start by providing a mathematical formulation and we analyze the complexity and some particular cases of the problem. Then, we propose a heuristic method for solving the NP-hard 3-machine case, which we evaluate by conducting tests on Taillards benchmark. These tests give satisfying results and show that the heuristic ensures good performance when the two flows have close numbers of jobs.

Une méthode intégrée pour la gestion des chaînes logistiques durables

Nous proposons une méthode intégrée pour la planification des chaînes logistiques (CL) durables, structurée en trois phases. La première fait le lien entre la performance durable et les décisions de planification des opérations de la CL. La deuxième permet de rendre compte des caractéristiques du système de production mis en œuvre. Dans la troisième phase, la planification de la CL est optimisée en tenant compte de sa performance économique, environnementale et sociale. Pour mettre en avant la valeur pratique de notre méthode, nous l’avons appliquée à un problème de planification tactique. Nous avons obtenu plusieurs solutions de compromis présentant différents niveaux de performances économique, environnementale et sociale, permettant au décideur de choisir la solution qui correspond le mieux à sa stratégie.

An Integrated Approach for the Optimization of the Sustainable performance: a Wood Supply Chain

This paper proposes an integrated approach that embeds the economic, environmental and social performances in the planning activities of the supply chain (SC). The approach is applied on a realistic case study inspired by the lumber industry where divergent manufacturing processes and various cutting patterns are involved. We first identify the sustainability objectives to be measured. Then, we link these objectives to the SC decision planning. Next, we define performance measures to assess the achievement of each objective. This triptych-based approach is transposed to a multi-objective mathematical programming (MOP) that serves as a performance optimizing and assessing tool. The MOP models a tactical planning problem where the SC is represented as a network of activities. The problem is resolved using the weighted sum method.