運輸成本與批量有關之買賣整合存貨模式

存貨與運輸問題將影響物流系統之營運績效，也是影響供應鏈成功與否的兩大因素。以往的整合存貨模式中，經常假設運輸成本為一已知固定常數，或是將運輸成本視為固定訂購或設置成本的一部分，甚至是略而不計。如此一來，將會使運輸成本的影響無法適當地反應於存貨相關決策中，而無法真正達到供應鏈成員成本最小化（利潤最大化）之目標。本研究在隨機需求環境下，建構運輸成本具增量及所有單位折扣的買賣整合存貨模式，其中缺貨發生時考慮欠撥待補情形。在買賣聯合總成本最小化的目標下，先以計量方法探討模式的特性及最佳解的條件，而後建立求解演算法，以求得對買賣雙方而言，最佳的訂購量、再訂購點及運送次數。此外，本研究以前置時間內需求量服從常態分配之模式為例，利用數值範例說明模式的求解結果，並進行敏感度分析以探討各參數值的改變對最適生產、訂購及運送策略的影響。

Inventory and transportation problems will influence the performance of logistics system, and they also play important roles in a supply chain. Previous studies on integrated inventory models often assumed that the transportation cost is a constant. As such, the impact of transportation cost on lot size and shipment decisions may not really be reflected. This study presents a model to address the vendor-buyer integrated inventory system with stochastic demand, where shortages are backordered. The transportation cost is assumed dependent on shipment size, and both the incremental discount and all units discount schedules are considered. The objective is to minimize the joint total cost by simultaneously optimizing the order/shipment lot size, reorder point, and number of shipment lots from the vender to the buyer. The solution procedures based on the classical optimization technique are proposed to help finding the optimal solution. Besides, numerical examples for a special case where lead time demand is distributed normally are provided to illustrate the results of proposed models. Sensitivity analysis is performed to examine the effects of problem parameters on the optimal inventory and delivery strategies.