Single-machine scheduling with periodic and flexible periodic maintenance to minimize maximum tardiness.

International audienceThis paper considers a single machine scheduling problem with several maintenances periods. Specially, two situations are investigated. In the first one, maintenance periods are periodically fixed : maintenance is required after a periodic time interval. In the second one, the maintenance is not fixed but the maximum continuous working time of the machine which is allowed is determined. The objective is to minimize the maximum tardiness. These problems are known to be strongly NP-hard. We propose some dominance properties and an efficient heuristic. Branch-and-bound algorithms, in which the heuristics, the lower bounds and the dominance properties are incorporated, are proposed and tested computationally

Scheduling predictive maintenance in flow-shop.

International audienceAvailability of production equipments is one major issue for manufacturers. Predictive maintenance is an answer to prevent equipment from risk of breakdowns while minimizing the maintenance costs. Nevertheless, conflicts could occur between maintenance and production if a maintenance operation is programmed when equipment is used for production. The case studied here is a flow-shop typology where machines could be maintained once during the planning horizon. Machines are able to switch between two production modes. A nominal one and a degraded one where machine run slowly but increase its remaining useful life. We propose a mixed integer programming model for this problem with the makespan and maintenance delays objective. It allows to find the best schedule of production operation. It also produces, for each machine, the control mode and if necessary the preventive maintenance plan

Takayasu arteritis in childhood: retrospective experience from a tertiary referral centre in the United Kingdom.

Takayasu arteritis (TA) is an idiopathic large-vessel vasculitis affecting the aorta and its major branches. Although the disease rarely affects children, it does occur, even in infants. The objective of this study was to evaluate the clinical features, disease activity, treatment and outcome of childhood TA in a tertiary UK centre

Une approche multi-agents coopératifs pour la gestion des ressources matérielles dans un contexte multi-sites de e-manufacturing.

International audienceDans cet article, nous proposons une modélisation basée sur le paradigme des systèmes multi-agents coopératifs appliquée à la gestion de ressources matérielles distribuées dans un environnement d'entreprises multisites distribués. Cette gestion constitue actuellement un challenge pour tous les producticiens du fait des influences économiques et technologiques modernes qui affectent ce genre d'entreprises. En effet, la redondance d'un stock d'un article quelconque dans plusieurs sites affecte négativement la santé économique de l'entreprise en tout, ce qui nous pousse à la recherche de méthodes optimales pouvant assurer un équilibrage de charge en matière de ces ressources entre les différents sites. Pour cela nous exploitons la plateforme Internet reliant les sites et en appliquant la technologie des Web Services basée sur les agents (agent demandeur, agent fournisseur et agent annuaire), nous mettrons en oeuvre une dynamique de coopération entre site déficitaire en article k et site excédentaire du même article et en généralisant ce principe à tous les articles, nous réaliserons l'équilibrage dynamique pouvant éviter à l'entreprise les sur-stockages et les sous-stockags de ces ressources matérielles

Robustness measure for fuzzy maintenance activities schedule.

International audienceSkills management in industry is one of the most important factors in order to obtain good performance with production means. Especially in the field of maintenance services where the different practical knowledge or skills are their working tools. We address, in this paper, both the assignment and scheduling problems that can be found in a maintenance service. Each task that has to be performed is characterized by the level of skill required. The problem lies with making the decision of which time is the right time for the assignment and scheduling of the correct resource to do the task. For human resources, all skill levels are different, they are considered as unrelated parallel machines. Our aim is to assign new tasks to the adequate resources by giving to the maintenance expert a good and robust possibility

Proactive, dynamic and multi-criteria scheduling of maintenance activities.

International audienceIn maintenance services skills management is directly linked to the performance of the service. A good human resource management will have an effect on the performance of the plant. Each task which has to be performed is characterised by the level of competence required. For each skill, human resources have different levels. The issue of making a decision about assignment and scheduling leads to finding the best resource and the correct time to perform the task. The solve this problem, managers have to take into account the different criteria such as the number of late tasks, the workload or the disturbance when inserting a new task into an existing planning. As there is a lot of estimated data, the managers also have to anticipate these uncertainties. To solve this multi-criteria problem, we propose a dynamic approach based on the kangaroo methodology. To deal with uncertainties, estimated data is modelled with fuzzy logic. This approach then offers the maintenance expert a choice between a set of the most robust possibilities

Static et dynamic scheduling of maintenance activities under the constraints of skills.

International audienceSkill management in industry is one of the most important factors required in order to obtain optimal performance of the production system. This is of particular importance in the field of maintenance where the different practical knowledge or skills are the working tools used. We address, in this paper, both the assignment and scheduling problems that may be found in a maintenance service. Each task that has to be performed is characterized by the level of skill required. The problem lies with making the decision of which time is the right time for the assignment and scheduling of the correct resource to do the task. We introduce both static and dynamic scheduling, applied to the maintenance task assignment. To confer a maximum robustness to the obtained schedule, tha approach proposed in this paper is completed by a proactive methodology which takes into account possible variations

Dynamic scheduling of maintenance activities under uncertainties.

International audienceCompetencies management in the industry is one of the most important keys in order to obtain good performance with production means. Especially in maintenance services field where the dierent practical knowledges or skills are their working tools. We address, in this paper, the both assignment and scheduling problem that can be found in a maintenance service. Each task that has to be performed is characterized by a competence level required. Then, the decision problem of assignment and scheduling lead to find the good resource and the good time to do the task. For human resources, all competence levels are dierent, they are considered as unrelated parallel machines. Our aim is to assign dynamically new tasks to the adequate resources by giving to the maintenance expert a choice between the robustest possibilities