Developing of Inventory Management Model Considering Simultaneous Ordering in a Multi-levels and Multi-product Supply Chain

In recent years, an integrated assessment of the suppliers, producers, distributors and costumers that make up the supply chain components is one of the areas that has received much attention. The inventory management in supply chain is one of the most important issues because a major amount of company assets lies in the amount of circulating inventory. So issues relating to inventory management in supply chain with the objective of minimizing the total cost of supply chain and unit cost of the final product the utmost importance. In this paper, a mathematical model for multi-product inventory management in a multi-level supply chain consisting of the multi-supplier, a manufacturer, and several retailers is presented. The model determines different factors such as the optimum ordering of the raw materials and optimal level of the production and optimal ordering time and quantity of the products by retailers at each level of the supply chain, with the objective of minimizing inventory management costs in the integrated supply chain. Since the developed model is a mixed nonlinear model, to achieve the solution, genetic algorithm is used to determine the optimal values of variables, also the implementation of the proposed method is demonstrated using some numerical example