عنوان مقاله [English]
In this paper, production planning in the process industry is studied. It is assumed that several products can be produced concurrently. The market demand of each product follows a Poisson distribution. The aim of this article is to maximize the adaptation of production output to arrival demand. To achieve this goal, a cyclic point of view to production processes is introduced and a heuristic two-stage model is developed to minimize the inventory holding costs and shortage costs. At the first stage, the optimum inventory level of each product at the beginning of each cycle (OIL) is determined. If the actual in hand inventory level of a product at the beginning of a cycle is equal to its determined amount at the first stage, the expected inventory holding and shortage costs of the product will be minimal during that cycle. At the second stage, considering the actual in hand inventory level of each product at the beginning of a cycle, the optimum combination of production volumes is determined, so that, firstly, production system parameters are satisfied and, secondly, the expected inventory levels at the end of the cycle will be as near to OIL as possible.to OIL as possible. To illustrate this, a numerical example is described.