en و موضوعات مربوط Other Related Subject پژوهشي Research <span style="FONT-FAMILY: "Times New Roman","serif" FONT-SIZE: 11pt mso-ansi-language: EN-US mso-fareast-font-family: 'Times New Roman' mso-fareast-language: EN-US mso-bidi-language: FA"><em>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.</em></span> Supply Chain; Multi Echelon Inventory System; Normal Distribution; N-Fold Convolution 65 72 http://ijiepr.iust.ac.ir/browse.php?a_code=A-10-1-134&slc_lang=en&sid=1 Maghsoud Amiri amiri@atu.ac.ir 180031947532846001554 180031947532846001554 Yes Associate Professor, Industrial Management Department, Faculty of Management and Accounting, Allameh Tabatabaei University, Tehran, Iran Mehdi Seif barghy 180031947532846001555 180031947532846001555 No Assistant Professor, Technical and Engineering Department, Alzahra University Laaya Olfat 180031947532846001556 180031947532846001556 No Associate Professor, Industrial Management Department, Faculty of Management and Accounting, Allameh Tabatabaei University, Tehran, Iran Seyed Hossein Razavi Hajiagha 180031947532846001557 180031947532846001557 No PhD Candidate, Industrial Management Department, Faculty of Management and Accounting, Allameh Tabatabaei University, Tehran, Iran