Modeling of Scheduling and Economic Lot Sizing In Distributed Permutation Flow Shops with Non-Identical Multi Factory

This paper addresses a new mathematical model of economic lot sizing and scheduling problem in distributed permutation flow shop problem with a number of non-identical factories and machines that have not been considered in previous articles. For this purpose, different products must be distributed between the factories then assignment of products to factories and sequencing of the products assigned to each factory has to be derived. The objective is to minimize the sum of setup costs, work-in-process inventory costs, finished products inventory costs per unit of time and total production cost that consists of cost of unbalanced assignment of products between factories. Since the proposed model is NP-hard, an efficient hybrid Vibration Damping Optimization with Imperialist Competitive Algorithm and Simulated Annealing are considered to solve the model. In addition, Genetic Algorithm and VDO are used for comparison. In order to determine the best value of algorithms parameters that result in a better solution, a fine-tuning procedure according to Response Surface Methodology is executed. The results show that the HVDO has a better performance in achieving the minimum goal in this problem.