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Chaari T.,University of Lille Nord de France | Chaari T.,University of Valenciennes and HainautCambresis | Chaabane S.,University of Lille Nord de France | Chaabane S.,University of Valenciennes and HainautCambresis | And 3 more authors.
International Journal of Computer Integrated Manufacturing | Year: 2011

Most of scheduling methods consider a deterministic environment for which the data of the problem are known. Nevertheless, in reality, several kinds of uncertainties should be considered, and robust scheduling allows uncertainty to be taken into account. In this article, we consider a scheduling problem under uncertainty. Our case study is a hybrid flow shop scheduling problem, and the processing time of each job for each machine at each stage is the source of uncertainty. To solve this problem, we developed a genetic algorithm. A robust bi-objective evaluation function was defined to obtain a robust, effective solution that is only slightly sensitive to data uncertainty. This bi-objective function minimises simultaneously the makespan of the initial scenario, and the deviation between the makespan of all the disrupted scenarios and the makespan of the initial scenario. We validated our approach with a simulation in order to evaluate the quality of the robustness faced with uncertainty. The computational results show that our algorithm can generate a trade off for effectiveness and robustness for various degrees of uncertainty. © 2011 Taylor & Francis. Source


Boujelbene M.,University of Sfax | Boujelbene M.,Institute Superieur Of Gestion Industrielle Of Sfax | Dhouibi S.,University of Sfax | Kharrat M.,University of Sfax | And 3 more authors.
Journal of Bionic Engineering | Year: 2012

In this work, a friction and wear simulator was used to reproduce the Anterior-Posterior (AP) sliding and the Flexion-Extension (FE) rotation generated in the knee joint during human gait cycle. We chose to simplify the contact geometry between the Total Knee Arthroplasty (TKA) femoral component and tibial insert. A 304L stainless steel cylinder which replaces the femoral component was loaded onto a flat High Density Polyethylene (HDPE) block which replaces the tibial insert. The tribological behavior of the considered contact was analyzed by tracking the number of cycles, the friction coefficient, the roughness of the wear track on HDPE, the HDPE weight loss and the damage mechanisms. The friction coefficient shows a gradual increase with the number of cycles for both AP and FE kinematics. The evolution of friction coefficient with the number of cycles is not affected by the value of the imposed normal load in the case of AP sliding. For the FE rotation, decreased friction coefficient is obtained when the imposed normal load increases. For both considered AP and FE kinematics, the roughness of the wear track on the HDPE is not affected by the imposed normal load. It shows a progressive decrease when the number of cycles increases. The wear of HDPE obeys the Archard law and the wear coefficient increases with the normal force. For a given value of normal load, the obtained wear coefficient for the AP sliding is larger than that obtained for FE rotation. A predominant adhesive wear mechanism was identified for both AP and FE kinematics. Under the same normal load, damage development in terms of plastic deformation, micro-cracking and debonding is more pronounced for the AP sliding if compared with the FE rotation. For a given kinematics, the damage severity increases with the normal load. This finding is in good agreement with the predicted values of the wear coefficient according to the Archard law. © 2012 Jilin University. Source


Boujelben M.A.,Unite de Recherche GIAD | De Smet Y.,Free University of Colombia | Frikha A.,Institute Superieur Of Gestion Industrielle Of Sfax | Chabchoub H.,Unite de Recherche GIAD
International Journal of Approximate Reasoning | Year: 2011

We consider ranking problems where the actions are evaluated on a set of ordinal criteria. The evaluation of each alternative with respect to each criterion may be imperfect and is provided by one or several experts. We model each imperfect evaluation as a basic belief assignment (BBA). In order to rank the BBAs characterizing the performances of the actions according to each criterion, a new concept called RBBD and based on the comparison of these BBAs to ideal or nadir BBAs is proposed. This is performed using belief distances that measure the dissimilarity of each BBA to the ideal or nadir BBAs. A model inspired by Xu et al.'s method is also proposed and illustrated by a pedagogical example. © 2011 Published by Elsevier Inc. Source


Kharrat A.,Institute Superieur Of Gestion Industrielle Of Sfax | Chabchoub H.,Institute Superieur Of Gestion Industrielle Of Sfax | Aouni B.,Aid Research Group
International Journal of Innovative Computing and Applications | Year: 2010

This paper proposes an interactive optimisation method for imprecise multiple-objective decision-making situations. The aim of the proposed approach is to integrate explicitly the decision-maker's (DMs) preferences within the interactive imprecise goal programming model. The DMs preferences will be expressed through the satisfaction functions concept. The new interactive imprecise goal programming approach is solved by the taboo central memory-simulated annealing algorithm. The use of this meta-heuristic allows the proposed approach to deal with large scale decision-making situations. The proposed approach will be illustrated through some examples. Copyright © 2010 Inderscience Enterprises Ltd. Source


Kharrat A.,Institute Superieur Of Gestion Industrielle Of Sfax | Dhouib S.,Institute Superieur Of Gestion Industrielle Of Sfax | Chabchoub H.,Institute Superieur Of Gestion Industrielle Of Sfax | Aouni B.,Laurentian University
International Journal of Data Analysis Techniques and Strategies | Year: 2011

Engineering design problems are usually formulated as non-linear problems with integer, discrete or continuous variables. This paper presents a new interactive procedure to handle these kinds of problems. This procedure is based on the interactive goal programming model and the concept of satisfaction functions which are used to elucidate and integrate explicitly the decision-maker's preferences. A record-to-record travel (RRT) technique is adapted to solve this new interactive goal programming model. The proposed approach provides a satisfactory solution in the presence of conflicting objectives with a minimum distance from the fixed goals. Two engineering design problems are presented to illustrate the applicability and the performance of the proposed interactive technique. Copyright © 2011 Inderscience Enterprises Ltd. Source

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