Minimizing makespan in flowshop with time lags

We consider the problem of minimizing the makespan in a flowshop involving maximal and minimal time lags. Time lag constraints generalize the classical precedence constraints between operations. We assume that such constraints are only defined between operations of the same job. We propose a solution method and present several extensions.Comment: 2 pages. Also available at http://hal.inria.fr/inria-0000014

Modeling and decision tools for supply chain control

Supply Chain Management implies a greater integration of model and decision tools. First transport models and production manufacturing models must be considered jointly and not separately. Second new Supply Chain structures, such as Extended Enterprises and Virtual Enterprises, induce negotiations concerning costs, delays and quality and exchange of knowledge and data, between various partners, who can have been in strong competition and want to keep some data quite secret while sharing other data with some partners of the Supply Chain. Some flow exchanges have been currently regulated by contracts with penalty systems; a more general control system needs to be designed. In consequence, new decision tools must be proposed at each level of the hierarchical decision structures: strategic, tactic and operational levels. In particular, new decision systems must be designed for the planning level including several partners of the Supply Chain and new scheduling tools generalizing classical scheduling models with new constraints and criteria linked to just-in-time strategies and to negotiation approaches

A window time negotiation approach at the scheduling level inside supply chains

International audienceWe consider a supply chain consisting in a network of enterprises with independent decision centers. The products of the assembly enterprise are produced using components and/or sub products supplied by other enterprises or external suppliers. We are at the scheduling level and each enterprise builds its own schedules, which are dependent. Negotiations between decision centers can be expressed in term of penalty functions associated with soft and hard release and due dates. At each negotiation point, hard release and due dates are considered as imperative constraints, while soft release and due dates define soft intervals and induce earliness and tardiness penalties. Any interval can be modified during the negotiation process. A global solution is searched by an iterative decomposition approach including alternatively bilateral negotiations of the soft and hard constraints and just in time scheduling, minimizing the local total sum of penalties, built by approximation approaches. We assume that production centers are flow shop. To solve each local just-in-time scheduling problem, we propose an approximation approach based on meta-heuristics, in which a solution is described by the job order on each machine and is evaluated using a “pert cost” algorithm. A semi-decentralized control is suggested to assume the negotiation convergence

Minimisation de la somme des retards pour les problèmes d'ordonnancement à une machine

Dans cet article, nous démontrons un théorème qui présente une condition suffisante d'optimalité locale pour le problème d'ordonnancement du type n/1/ri/\sumTi. Cette condition nous permet de définir un nouveau sous-ensemble dominant de solutions pour ce problème qui est NP-difficile. Nous utilisons les résultats obtenus pour construire un algorithme approché polynômial et donnons une majoration de l'erreur commise par cet algorithme dans le pire des cas

Single product scheduling and transportation optimization in a supply chain

In this paper we consider a basic supply chain composed of one or several suppliers that provide components needed by a manufacturer. The manufacturer has to deliver finished products to only one customer before given delivery dates. We first verify if the associated decision problem is feasible or not with unlimited transportation capacities. At this decision level we assume that for the components, the delivery dates and the associated quantities are known. We further integrate progressively to the model more realistic transportation constraints and costs to be optimized : number of travels with unlimited number of trucks with unlimited capacity, number of travels with unlimited number of trucks with limited capacity and finally we consider limited number of physical trucks as a perspective

Single machine scheduling problems with release dates

The single machine scheduling problems have been extensively studied with various criteria to be optimized and under various assumptions. In this work, we review some results obtained recently in the case of different release dates. Most problems with different release dates are NP-hard. Some researchers have proved some dominance properties or sufficient conditions for local optimality which lead to an optimal schedule in some specificic cases. We present some properties or conditions for two regular criteria, total tardiness and total flow time

A hybrid decomposition approach using increasing clusters for solving scheduling problems with minimal and maximal time lags

In this article we present a priority rule construction algorithm couopled with a cluster decomposition method in order to construct feasible solutions for general scheduling problems with minimal and maximal time lag constraints. Algorithm performances have been tested on job shop scheduling problems and also a real chemical freeze-drying process

Gestion de systèmes d'assemblage multi-produits avec approvisionnement aléatoire

Nous nous intéressons à l'optimisation de la planification d'un système d'assemblage multi-produits. Les composants sont commandés chez des fournisseurs extérieurs avec des délais de livraison non négligeables. Un même type de composant peut être utilisé pour l'assemblage de plusieurs types de produits. L'assemblage d'un produit demande un ou plusieurs composants de différents types. Nous étudions le fonctionnement du système en régime permanent. Nous supposons que la demande de chaque produit est identique à chaque période de temps, mais que les dates de livraisons des composants subissent des déviations aléatoires suivant des lois de distribution de probabilités quelconques mais connues. La capacité de production est supposée illimitée et les seuls coûts qui interviennent dans le critère à optimiser sont des coûts de stockage de composants et des coûts de rupture de produits finis. Pour résoudre ce problème, nous utilisons une technique d'horizon glissant en croisant un modèle de programmation linéaire, des calculs de prévisions et des méthodes de simulation. Nous présentons les caractéristiques fondamentales des modèles utilisés, des expérimentations numériques et une méthodologie d'utilisation pratique

Gestion collaborative et distribuée des approvisionnements intégrant le transport

L'enjeu croissant du problème des transports dans la gestion des chaînes logistiques, implique que les décisions de management intègrent étroitement problèmes de production et problèmes de transport. Dans ce contexte, nous nous intéressons ici à la gestion collaborative des approvisionnements dans une chaîne logistique qui prend en compte la dimension transport. L'architecture industrielle étant distribuée, les mécanismes proposés cherchent à garantir à la fois, l'autonomie décisionnelle des entreprises constituant le réseau et aussi la convergence du processus. Le modèle proposé s'appuie sur une architecture multi agents et sur des mécanismes de négociation. Cette démarche utilise deux modèles mathématiques. Le premier vise à organiser la manière optimale de transport sous contraintes amont et aval. Le second modèle permet la recherche et le choix des prestataires de transport en optimisant le coût global. La méthode de résolution utilise un solveur muni d'une procédure par séparation et évaluation

Collaborative model for customer request ordering: research and selection of substitute suppliers

In this paper, we propose supplier research protocol and decision tools for supplier selection. The architecture of the negotiation and decision making is supported by a multi agent system and uses mixed integer programming models and solvers. The supply chain is composed by autonomous enterprises. Each enterprise must reach, in the same time, local and global goals. The research protocol is implemented in a virtual agent “Tier Negotiator Agent (TNA)” implanted in each tier of the supply chain, which provides human decision makers with data tables and suggests them to follow some directives. One TNA is activated each time a customer does not find sufficiently components for covering its needs and the protocol can activate TNA of upstream tiers