Simulation of Manufacture Inventory Strategy Based on Through Train Supplies

This paper focus on inventory strategy of manufactures on the basis of bulk raw material supply provided by railway through trains. The outbound quantity of materials is rely on the stochastic output, such as the probability distribution of daily sales volume of certain products, production breakeven point and the designed capacity of progressive assembly line. The inbound quantity is determined by the railway train diagram and landed weight in accordance with orders. The time step method is used to obtain optimum solution by computer simulation. The model is composed of inventory holding costs, ordering costs based on order discount, procurement constant expense and material shortage costs. One example with given demand probability distribution and certain railway cargo transportation timetable is simulated by MATLAB program. The study reveals that computer simulation is more adequate for mass-production scale manufactures to make inventory management decisions. The result illustrates that order quantity and departure time-interval of through train play more important role in inventory simulation system.

摘要基于铁路装车地直达列车的大宗原材料供应方式，研究生产企业库存优化问题。结合企业特定产品日销量的概率分布、产量盈亏平衡点、流水线设计能力等确定库存的随机输出量，依据装车地直达列车运行图的列车到达时刻及卸货量作为库存的输入量及输入时点。采用基于时间步长法的系统仿真方法获得原材料采购环节的库存优化策略，综合原材料库存持有成本、批量折扣成本、订货固定成本，以及缺货成本建立仿真模型。利用MATLAB编程获得特定算例的仿真最优解，模拟结果表明，订货量、直达列车发车间隔是左右库存仿真映像优化水平的核心要素。