determination of a desirable inventory policy in a three echelon multilayer supply chain with normal demand

inventory control is one of the most important issues in supply chain management. in this paper, a three-echelon production, distribution, inventory system composed of one producer, a set of wholesalers and retailers is considered. costumers' demands can be approximated by a normal distribution and the inventory policy is a kind of continuous review (r, q). in this paper, a model based on standard cost structure of inventory systems is developed and a heuristic algorithm is designed to optimize the developed model. the application of model is examined in a series of designed experiments that are compared with simulation results. these comparisons verify the validity of the model. regarding to real complexities in three-echelon systems analysis, the proposed method can have a wide application in practical problems with the same considerations and assumptions. in addition, this method can be used to approximate those systems that follow a poisson demand.