平行供貨二階(S-1,S)存貨系統之研究

Abstract

本研究探討平行供貨二階(S-1,S)存貨系統，此研究假設顧客需求為獨立之Poisson分配，及運送時間服從任意分配。顧客之服務水準分為兩部份：(一)顧客需求由本身存貨自行供貨滿足的機率，(二)銷售商缺貨時，向其它的銷售商調貨以滿足顧客需求的平行供貨機率。而存貨總成本則考慮持有成本、平行供貨成本及缺貨成本。在平行供貨及自行供貨服務水準限制條件下，最小化存貨總成本，求解最佳庫存配置。本研究分析比較各銷售商間不可平行供貨、有條件平行供貨及無條件平行供貨三種二階(S-1,S)存貨模式的存貨配置關係後，訂定平行供貨二階(S-1,S)存貨系統各存貨點的最佳庫存配置範圍。隨之在此範圍內，搜尋整個系統的最佳存貨配置。最後以一案例說明本研究的存貨配置演算法。

The problem we address is to determine safety stocks in a two-echelon (S-1,S) inventory system with lateral resupply. In this system we assume that demands are Poisson process and the distributions of resupply time are arbitrary. There are two parts of service levels are considered. One is the satisfied rate that a demand of customer is met immediately by stock on hand. The other is the probability that a demand is met by lateral resupply from other retailers. In this system we develop an approach to determine the stock levels regarding the objectives of holding, shortages and lateral resupply costs and service levels restrictions. The proposed approach is developed by comparing stock allocations among three types of two-echelon(S-1,S) inventory system. One is that lateral resupply is prohibited. The others are free lateral resupply and restricted lateral resupply. Then we can determine the searching space for the optimal stock levels of two-echelon(S-1,S) inventory system with lateral resupply. Finally, an example is given to illustrate the procedure of the algorithm.