中文摘要：

针对上游供应链厂商提供数量折扣情况，将传统采购中的数量折扣同JIT采购结合起来，建立了一个基于数量折扣的综合订货模型。模型探讨了在典型的JIT采购方式“一次订购多次送货”的基础上，针对上游供应链厂商提供数量折扣安排的情况，供应链下游厂商如何选择最优的订货策略：将订货量、送货时点以及送货量作为决策变量，考虑允许缺货且各送货区间需求不确定的情况，运用遗传算法对问题进行求解，并给出了数值算例。

英文摘要：

How a Manufacturer can structure the terms of purchasing strategy under JIT environment when the suppliers offer quantity discounts is analyzed. Quantity discounts and JIT purchasing are combined and then set up a new JIT purchasing model based on quantity discounts to take advantages of the two purchasing methods. The model considers small lot sizing and frequent deliveries policies in JIT purchasing system with variable demand and varia- ble supply. The purpose of this study is to minimize the total relevant costs of the Manufacturer, so as to obtain the optimal number of deliveries, shipping points and shipping quantities in each shipping point. The algorithm procedure and numerical example for the model are also given.