关键词: 库存控制, 双需求类, 静态配给策略, 绩效衡量, 服务水平约束

Abstract: We consider a periodic review, infinite horizon, backlogging inventory system with two demand classes, where the high priority class has a higher target service level than the low priority one. The system applies a base-stock policy and a constant critical level policy, under which high priority demands are fulfilled firstly while low priority ones are satisfied only if on-hand inventory is more than a constant critical level. The objective is to minimize the expected ending on-hand inventory subject to two service level constraints. To improve computation efficiency, we propose a “Reservation Assumption”, under which the ending on-hand inventory is no less than the sum of high priority backorder level and the constant critical level by increasing low priority backorder level. We derive closed-form expressions for the approximate system performance, prove various monotone properties with respect to control parameters, characterize the zones of feasible solutions, and develop a solution procedure of the service level constraint problem. The numerical experiments show that our solution procedure performs well in both solution accuracy and computation efficiency.

Key words: inventory control, two demand classes, constant critical level policy, performance evaluation, service level constraints