Abstract: This paper considers an inventory service system with continuous-review(s,Q)replacement policy. The steady-state balance equations are set up based on queuing theory. And the probability distribution for inventory levels and the steady-state performance measures which are used to for the inventory control are derived. For minimizing the inventory cost function, an inventory control model with constrained service level is built. In view of the optimal model which is no-linear and constrained with integer type variables, an improved genetic algorithm(IGA)is used for searching for the optimums. The numerical results show that the inventory cost can be cut down by exerting service level constraint when target service level is greater than endogenetic service level of the inventory system.

Key words: control policy, inventory service system, service level, (s,Q)policy

摘要： 研究一个连续盘点的(s,Q)补货的库存服务系统。基于排队理论建立库存水平状态平衡方程,并推导出库存水平稳态概率分布以及作为库存控制的系统稳态性能指标。以库存成本最小化为目标,构建服务水平约束的库存控制模型。针对模型的非线性约束与整数型变量的特征,采用一种改进的遗传算法(IGA)用于决策变量的寻优。数值实验表明,当目标服务水平大于库存系统内生的服务水平时,实施服务水平约束能够降低库存控制成本。

关键词: 控制策略, 库存服务系统, 服务水平, (s,Q)策略