Hélène Marian

Mathematical Model for Supply Planning of Multi-level Assembly Systems with Stochastic Lead Times

The deal for industrial companies is to satisfy their customers with the best quality, the most reliable lead times, and the lowest costs. One of the keys to achieve it is in the inventory control in the Supply Chain. Moreover, it is mandatory to possess necessary components in order to produce the requested products by the due date. But, as the components lead time is an unpredictable parameter, it is difficult to take it into account correctly. In this paper we deal with this question considering that each component has a fixed unit inventory cost; the finished product has an inventory cost and a backlogging cost per unit of time. Then, a general mathematical model for supply planning of multi-level assembly system is presented to calculate the expected value of the total cost which equals to the sum of the inventory holding costs for the components, the backlogging and the inventory holding costs for the finished product. The aim is to propose tools to adapt and parameterize the MRP method under lead time uncertainty.

Reducing the Research Space of Possible Order Release Dates for Multi-level Assembly Systems under Stochastic Lead Times

This paper proposes tools which will be used to optimize multi-level assembly under lead time uncertainty. One type of finished products and several types of components are considered. We suppose that each component has a fixed unit inventory cost and the finished product has backlogging and inventory holding costs per unit of time. The lead times of components are discrete random variables, and the costumers demand of the finished product is known. A reduced space of research is presented to strengthen optimization methods which have been applied for minimizing the sum of the average inventory holding cost for components and the average backlogging and inventory holding costs for the finished product.