@article { ISI:000337796300003, title = {Buffer dimensioning and control stations positioning with a space partitioning-tabu search approach}, journal = {INFOR}, volume = {51}, number = {1, SI}, year = {2013}, month = {FEB}, pages = {15-22}, abstract = {We propose an efficient heuristic method based on Space Partitioning (SP) and Tabu Search (TS) to solve the buffer sizing problem in unreliable production lines with several inspection stations. In such problem, we have an unreliable production line consisting of a certain number of machines and fixed-size buffers. These machines produce a single part with two different quality levels: conforming and non-conforming parts. The production line may contain inspection stations whose job is to reject the non-conforming parts from the line. The production line must meet a constant rate of demand for the conforming finished parts. The objective is to minimize the average long term combined storage and shortage costs, while also specifying the optimal location of inspection stations. This design problem is a difficult mixed integer nonlinear program. Solving even a small instance of 10 machines and one inspection station using a direct dynamic programming method takes hours. If we especially increase the number of machines or the inspection stations, the dynamic programming approach becomes drastically inefficient. The method we propose divides the search space into a set of disjoint subspaces using a space partitioning technique. Tabu search is used to intensify the search in the selected subspaces. This combined method finds optimal solutions for small instances in a fraction of dynamic programming time. For the largest instances (up to 20 machines) the dynamic programming approach was unable to solve, our method finds high-quality solutions in reasonable times.}, issn = {0315-5986}, doi = {10.3138/infor.51.1.15}, author = {Ouzineb, Mohamed and Mhada, Fatima and El Hallaoui, Issmail} } @article {9434372220130201, title = {Buffer dimensioning and control stations positioning with a space partitioning-tabu search approach.}, journal = {INFOR}, volume = {51}, number = {1}, year = {2013}, pages = {15 - 22}, abstract = {We propose an efficient heuristic method based on Space Partitioning (SP) and Tabu Search (TS) to solve the buffer sizing problem in unreliable production lines with several inspection stations. In such problem, we have an unreliable production line consisting of a certain number of machines and fixed-size buffers. These machines produce a single part with two different quality levels: conforming and non-conforming parts. The production line may contain inspection stations whose job is to reject the non-conforming parts from the line. The production line must meet a constant rate of demand for the conforming finished parts. The objective is to minimize the average long term combined storage and shortage costs, while also specifying the optimal location of inspection stations. This design problem is a difficult mixed integer nonlinear program. Solving even a small instance of 10 machines and one inspection station using a direct dynamic programming method takes hours. If we especially}, keywords = {Buffer storage (Computer science), Combinatorial Optimization, Dynamic programming, Heuristic algorithms, Inspection, Machine theory, Meta-heuristics, Production lines, Quality, Tabu search algorithm, Topology}, issn = {03155986}, url = {http://search.ebscohost.com/login.aspx?direct=true\&db=bth\&AN=94343722\&site=ehost-live}, author = {Ouzineb, Mohamed and Mhada, Fatima and El Hallaoui, Issmail} } @conference { ISI:000352386800113, title = {An exact method for solving the buffer sizing and inspection stations allocations problem}, booktitle = {PROCEEDINGS OF 2013 INTERNATIONAL CONFERENCE ON INDUSTRIAL ENGINEERING AND SYSTEMS MANAGEMENT (IEEE-IESM 2013)}, year = {2013}, note = {5th International Conference on Industrial Engineering and Systems Management (IEEE IESM), Mohammadia Sch Engn, Rabat, MOROCCO, OCT 28-30, 2013}, pages = {775-780}, publisher = {IEEE; IEEE Morocco Sect; I4e2; Univ Valenciennes Hannaut Cambresis; Univ Mohammed V Agdal Rabat; CNRST; CISIT; ENIM; ESITH; GDR MACS; LAMIH CNRS; IFSTTAR; IRT RAILENIUM; TEMPO}, organization = {IEEE; IEEE Morocco Sect; I4e2; Univ Valenciennes Hannaut Cambresis; Univ Mohammed V Agdal Rabat; CNRST; CISIT; ENIM; ESITH; GDR MACS; LAMIH CNRS; IFSTTAR; IRT RAILENIUM; TEMPO}, abstract = {An unreliable single part type transfer line with fixed inter machine buffer sizes is considered. In general, imperfect machines operating with imperfect raw material, or partially processed raw material, will result in the production of a mix of conforming and non conforming parts. The problem of optimal joint assignment of buffer sizes and inspection station positions is here considered where we assume that defective parts are scrapped upon detection. The performance measure to be optimized is a combination of work in process storage and parts inspection costs, with an eye to determining the adequate number of inspection stations. We propose an exact method for solving this problem and large-scale numerical experiments are provided to demonstrate the efficiency of the proposed algorithm. Interesting properties of the problem are also denoted based on our empirical results.}, isbn = {978-2-9600532-4-1}, author = {Ouzineb, Mohammed and Mhada, Fatima and El Hallaoui, Issmail and Pellerin, Robert}, editor = {Aboutajdine, D and Skalli, A and Benchekroun, B and Artiba, A} } @conference { ISI:000352386800106, title = {(Q, s) models for inventory policy with random component procurement lead times}, booktitle = {PROCEEDINGS OF 2013 INTERNATIONAL CONFERENCE ON INDUSTRIAL ENGINEERING AND SYSTEMS MANAGEMENT (IEEE-IESM 2013)}, year = {2013}, note = {5th International Conference on Industrial Engineering and Systems Management (IEEE IESM), Mohammadia Sch Engn, Rabat, MOROCCO, OCT 28-30, 2013}, pages = {718-726}, publisher = {IEEE; IEEE Morocco Sect; I4e2; Univ Valenciennes Hannaut Cambresis; Univ Mohammed V Agdal Rabat; CNRST; CISIT; ENIM; ESITH; GDR MACS; LAMIH CNRS; IFSTTAR; IRT RAILENIUM; TEMPO}, organization = {IEEE; IEEE Morocco Sect; I4e2; Univ Valenciennes Hannaut Cambresis; Univ Mohammed V Agdal Rabat; CNRST; CISIT; ENIM; ESITH; GDR MACS; LAMIH CNRS; IFSTTAR; IRT RAILENIUM; TEMPO}, abstract = {This paper considers inventory models of (Q, s) type with Q the order-quantity and s the order point. In general, an optimal choice of control parameters (Q and s) will depend on the characteristics of replenishment lead time and the demand process, as well as holding and shortage costs. Although many studies have treated lead time as constant, focusing only on demand variability, a number of authors have shown that a stochastic lead time is an issue that can have significant impact on inventory models and systems. This paper addresses the model when supply is assumed to have an exponential lead time distribution, and the {\textquoteleft}{\textquoteleft}customer{{\textquoteright}{\textquoteright}} itself is an exponential unreliable manufacturing plant, aiming for a constant mean production rate; thus both supply and demand have random characteristics. Under a so-called averaging principle approximation, we derive closed form expressions of the quantities of interest and illustrate their application in the optimization of the Q and s parameters.}, isbn = {978-2-9600532-4-1}, author = {Mhada, Fatima and Malhame, Roland and Pellerin, Robert and Sadr, Javad and Gharbi, Ali}, editor = {Aboutajdine, D and Skalli, A and Benchekroun, B and Artiba, A} } @article {5570174020110101, title = {Approximate performance analysis of CONWIP disciplines in unreliable non homogeneous transfer lines.}, journal = {Annals of Operations Research}, volume = {182}, number = {1}, year = {2011}, pages = {213 - 233}, abstract = {For a given choice of the maximum allowable total storage parameter, the performance of constant work-in-process (CONWIP) disciplines in unreliable transfer lines subjected to a constant rate of demand for parts, is characterized via a tractable approximate mathematical model. For a ( n?1) machines CONWIP loop, the model consists of n multi-state machine single buffer building blocks, separately solvable once a total of ( n?1) unknown constants shared by the building blocks are initialized. The multi-state machine is common to all building blocks, and its n discrete states approximate the joint operating state of the machines within the CONWIP loop; each of the first ( n?1) blocks maps into a single internal buffer dynamics, while the nth building block characterizes total work-in-process (wip) dynamics. The blocks correspond to linear n component state equations with boundary conditions. The unknown (shared) constants in the block dynamics are initialized and calculated by means of s}, keywords = {Aggregation operators, CONWIP, Decomposition method (Mathematics), Decomposition/aggregation methods, Forward Kolmogorov equations, Mathematical models, Monte Carlo method, Operations research, Performance evaluation, Reliability (Engineering)}, issn = {02545330}, url = {http://search.ebscohost.com/login.aspx?direct=true\&db=iih\&AN=55701740\&site=ehost-live}, author = {Mhada, Fatima and Malhame, Roland} }