Christophe Varnier

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

This paper considers a single-machine scheduling problem with several maintenances periods. Specifically, 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.

Resolution Of The Cyclic Multi-Hoists Scheduling Problem With Overlapping Partitions

AbstractThis paper deals with scheduling problem in electroplating facilities. To maximise the productivity of electroplating lines, a predictive approach can be used to find a sequence of hoist movements that can be cyclically repeated. This NP-hard problem is known as the Cyclic Hoist Scheduling Problem. An approach for the multi-hoists problem is suggested. The presented model uses Constraint Logic Programming for finding the optimal cyclic schedule for a given hoist assignment.

Constraint-based model for the cyclic multi-hoists scheduling problem

This article presents a method for the resolution of a material handling scheduling problem. The case studied is a real industrial problem. It consists of finding a cyclic schedule for hoist movements in a treatment surface shop. In this kind of facility, several hoists are used for all the handling operations and they have to share common zones. Then it is necessary to control that there is no collision. The mathematical formulation of the problem is based on a combination of disjunctive constraints. The constraints describe either movement schedule or collision avoidance. The resolution procedure presented identifies all the collision configurations and then uses a branch and bound-like algorithm to find the optimal solution of a given problem. The language chosen for our implementation is the constraint logic programming language: Prolog IV, which is able to solve constraints with rational variables. It actively uses the constraint propagation mechanism that can be found in several languages.

Hoist scheduling problem: an approach based on constraint logic programming

Scheduling the movements of a hoist in printed circuit board electroplating is known is the hoist scheduling problem (HSP). The objective of the HSP is to find an optimal cyclic sequence of moves for hoists. Results are already available for this problem, using classical operational research tools. They are briefly presented. Most of the proposed solutions are limited to the very specific initial model and are consequently difficult to apply in industrial problems. The constraint logic programming (CLP) approach to the problem is presented. A CLP model of the problem that allows modeling and solving more realistic cases is presented, and the results and the analysis of the solutions are outlined.<<ETX>>

Joint scheduling of jobs and Preventive Maintenance operations in the flowshop sequencing problem: a resolution with sequential and integrated strategies

This paper presents a comparative study on joint production and Preventive Maintenance (PM) scheduling according to the most interesting joint scheduling strategies: sequential and integrated ones regarding Flow Shop Problems (FSPs). For each strategy, we present three heuristics: Genetic Algorithms (GAs), Taboo Search (TS) and NEH heuristic. The proposed heuristics have been applied to non-standard test problems, which represent joint production and maintenance benchmark flowshop scheduling problems taken from Benbouzid et al. (2003). A comparison of the solutions yielded by the heuristics developed in this paper with the heuristic solutions given by Taillard (1993) is undertaken with respect to the minimisation of performance loss after maintenance insertion. The comparison shows that the proposed integrated GAs are clearly superior to all the analysed algorithms.

An integrated ACO approach for the joint production and preventive maintenance scheduling problem in the flowshop sequencing problem

In this paper, an integrated ACO approach to solve joint production and preventive maintenance scheduling problem in permutation flowshops is considered. A newly developed ant-colony algorithm is proposed and analyzed for solving this problem, based on a common representation of production and maintenance data, to obtain a joint schedule that is, subsequently, improved by a new local search procedure. The goal is to optimize a common objective function which takes into account both maintenance and production criteria. We compare the results obtained with our algorithm to those of an integrated genetic algorithm developed in previous works. The results and experiments carried out indicate that the proposed ant-colony algorithm provide very effective solutions for this problem.

A hybrid prognostics approach for MEMS: From real measurements to remaining useful life estimation

Abstract This paper presents a hybrid prognostics approach for Micro Electro Mechanical Systems (MEMS). This approach relies on two phases: an offline phase for the MEMS and its degradation modeling, and an online phase where the obtained degradation model is used with the available data for prognostics. In the online phase, the particle filter algorithm is used to perform online parameters estimation of the degradation model and predict the Remaining Useful Life (RUL) of MEMS. The effectiveness of the proposed approach is validated on experimental data related to an electro-thermally actuated MEMS valve.

Applying Ant Colony Optimization for the Joint Production and Preventive Maintenance Scheduling Problem in the Flowshop Sequencing Problem

In this paper a sequential resolution of the joint production and preventive maintenance scheduling problem in permutation flowshops is considered with the objective of minimizing the makespan. The proposed sequential algorithm, called SAS, consists of two steps: first the scheduling of the production jobs with Ant System algorithm (AS) by Dorigo and al. (1996) is considered. Then the insertion of the maintenance tasks is done according to several heuristics developed in previous works, taking the production scheduling as a strong constraint. Computational experiments are conducted on a large set of instances and the resulting joint ACO is presented.

Optimal Path Evolution in a Dynamic Distributed MEMS-Based Conveyor

We consider a surface designed to convey fragile and tiny micro-objects. It is composed of an array of decentralized blocks that contain MEMS valves. We are interested in the dynamics of the optimal path between two blocks in the surface. The criteria used for optimal paths are related to the degradation of the MEMS, namely its remaining useful life and its transfer time. We study and analyze the evolution of the optimal path in dynamic conditions in order to maintain as long as possible a good performance of the conveying surface. Simulations show that during usage the number of optimal paths increases, and that position of sources greatly influences surface lifetime.

Hoist Scheduling Problem: State-of-the-Art

Abstract In automated plating processes, hoists ensure the transfer of products between workstations. Scheduling their movements is known as the Hoist Scheduling Problem (HSP). It belongs to the class of strongly NP-hard problems (Lei and Wang, 1989b). Many studies, dealing with different complexity levels of the problem have been published, and the following classification should give the reader quite a large overview of them.