s.m. sajadi

The advent of new technologies, globalization of markets, customers' varied needs, and increasingly fierce competition, is making SMEs seek to improve engagement with their suppliers and cost management practices in order to survive. Thus, SMEs clearly need to focus on the interests of the entire supply chain by enacting win-win policies. In this study, we investigate a two-level inventory model featuring a manufacturer and a buyer in the competitive market with the policy of producing new products. Imperfect quality products and the capacity to rework are also considered in the model. In other words, because of the competitive nature of the market, any increase in price leads to a decrease in demand. The mathematical model is proposed over two scenarios: a scenario where shortage can occur, and one with no possibility of shortage. The objective function of the mathematical model revolves around the central goal of maximizing the total profit of the supply chain considering both independent and joint optimization by the supply chain members. A new algorithm is proposed to solve the mathematical model whose applicability is evaluated by giving a numerical example to the analysis software MATLAB. The final results are analyzed and discussed using sensitivity analysis approach.

Increasing business competitiveness forced companies to improve their business. Therefore, industry managers have found that it is necessary to focus on the supply of products in according to the wishes of the customer the quality and the cost of their intended use. We consider a three-stage supply chain involving multiple suppliers, manufacturer producing multiple type of product and a final customer. At each order, the manufacturer receives the raw material from a supplier based on optimal policy in a lot of size Q. The production process could produce additional nonconforming products, the manufacturer could be unavailable due to failures (following a general time-to failure distribution), and repair operations (following a general time-to-repair distribution) propose a control policy, which coordinates supplier selection, replenishment, production and quality inspection decisions. Upon reception, the manufacturer applies a simple lot-by-lot acceptance-sampling plan with attributes. This plan is characterized by a random sample of size n and an acceptance criterion c. Based on this inspection plan if the number of non-conforming items d found in this sample is equal to or less than c the lot will be accepted. Otherwise, the lot will be refused and returned to its original supplier and then a new order is placed. At this instant the manufacturer is not obliged to keep the same supplier. He can choose any one that offers better replenishment conditions. In this work. we aim to determine the optimal control policy for supplier selection replenishment and optimal quality control decisions that minimizes the total cost which includes inventory, backlog, inspection, replenishment and production costs. Coordinating decisions along the entire chain is critical since it requires determining carefully what to manufacture as well as what when and from whom to order. So simulation-based optimization is one of the methods for solving this problem. Numerical examples show the efficiency of the proposed method.