S I M U L A T I O N O F J I T M U L T I S T A G E S U P P L Y C H A I N A N D O P T I M I Z A T I O N O F O B J E C T I V E S

It is dicult to determine an inventory level all through a supply chain (SC), in such a way that the desired objectives, such as eectiveness and responsiveness, can be obtained. Simulation is a means of solving problems which cannot be solved by mathematical models, due to the complexity of the problems. Managers are, on the one hand, engaged in the strategic decision making of the chain, as well as various kinds of cooperation among members, and, on the other hand, with the quantities of inventory all through the chain. Strategies of each member of the supply chain and/or the whole supply chain can be based on meeting the needs (such as short-time delivery, producing new products, high level of availability of products, and so on) or eectiveness of the SC (low price of products, decreasing costs, and eectively using capital). Determining the level of inventory along a supply chain, in such a way that consumer satisfaction will be met to a favorable degree, taking into consideration responsiveness or eectiveness, is dicult. The present research is intended to study the inventory of a supply chain, as well as modeling the supply chain and determining multiple objectives in models for a four-stage, single-product supply chain. The use of metaheuristic techniques leads to optimization of these variables, which helps decrease 166 delay in both product delivery and inventory levels of SC.The present paper is aimed at JIT supply chain simulation together with optimization of the objectives of the SC. Variables of the simulation model include two types of Kanbans, namely; withdrawal and production, to determine the inventory level of SC and the batch size of delivery parts for each stage of the supply chain. Using metaheuristic techniques leads to optimization of these variables towards decreasing delay in the delivery and inventory levels of SC.