考慮預購商品的一些確定性存貨模式之最適訂購策略

OPTIMAL ORDERING POLICIES OF SOME DETERMINISTIC INVENTORY MODELS WITH ADVANCE BOOKING DISCOUNT ITEMS

翁明偉(Ming-Wei Weng)

指導教授 ： 張紘炬

淡江大學/管理學院/管理科學研究所博士班/博士(2009年)

https://doi.org/10.6846/TKU.2009.00910

摘要

在一般的商業交易行為中，我們發現到零售商基於增加市場占有率及降低未來需求的估計誤差等原因會提供顧客預購的價格折扣。此外，以往文獻通常假設需求率為一固定常數。然而由物品的生命週期看來，需求只有在穩定期才為一常數，通常是與時間有關。當需求對時間具有敏感性時，零售商如何決定物品的預購折扣率和訂購策略使其總利潤有最大值是值得探討的課題。 另外，我們也發現到：供應商基於某些原因如欲刺激零售商購買或買賣雙商簽訂供應鏈合約，會嘗試提供顧客信用交易等優惠。然而，事實上，零售商也可能提供顧客信用交易期限，以刺激需求來增加銷售收入。因此，我們考慮了供應商提供給零售商一個信用交易期限M ，同時零售商亦提供給顧客一個信用交易期限N，並在 N < M假設下，進一步探討零售商最適訂購量存貨模型。 再者，傳統EOQ模型大都假設零售商沒有倉庫容量限制，使零售商可以任意的訂購，事實上，自有倉庫是有容量限制的，當訂購的物品數量超過自有倉庫的容量限制時，零售商應考慮外租倉庫來儲存物品。以往文獻探討欠撥率時，顧客對於上游零售商的存貨水準 或是訂購週期有充分的訊息與瞭解前提下，顧客會因等候時間或負的存貨水準而影響其等候意願。因此，將假設單位時間缺貨成本為時間的線性函數，表示零售商負的存貨水準並不會影響到顧客的購買產品的忠誠度。即每單位的缺貨成本與等候時間長短有關，使得模型的應用更能符合實際情況。 本文係探討一些預先訂購物品的存貨系統，全文包括了三個存貨模型，第二章，探討在允許信用交易與預先訂購下之退化性物品的存貨模型。與之前文獻不同的是，假設與時間有關需求。第三章延續第二章的研究，探討允許預先訂購與在有限計畫期間內需求隨時間變動之最適訂購策略，並提出一個演算法協助零售商尋找最佳補貨次數與最適訂購週期。第四章則在探討需求率為固定常數且預先訂購的兩倉庫退化性物品存貨模式，不同以往的是假設單位時間缺貨成本為時間的線性函數且部分欠撥。進一步我們利用數理方法分別得到所提三種存貨模式最適解存在的充分且必要條件，並分別舉例說明其求解過程。最後，第五章為結論，並對本文各章所建構的存貨模型做一總結，同時提出未來的研究方向。

關鍵字

存貨 ； 有限計畫期間 ； 時間有關之需求 ； 信用交易 ； 預先定購 ； 兩倉庫

並列摘要

In business dealing, there exists many factors like advance booking discount to make retailers buy goods early. For companies, the advance booking discount strategy is common and useful in reality to decrease the estimation error in demand and to increase the market share. Furthermore, in real life, the demand is usually influenced by time. In the growth stage of a product life cycle, the demand rate can be well approximated by a linear form or exponential form. The retailer sells the product through an advance booking discount and aiming to optimize price discount and replenishment cycle time to maximize total profit per unit time.
Next, the supplier would offer the retailer a delay period M and the retailer could sell the goods and accumulate revenue and earn interest within the trade credit period. Furthermore, the retailer also offer the customer a delay period N to stimulate his/her customer demand to develop the retailer’s replenishment model(N < M ). Under these conditions, we model the retailer’s inventory system as a cost minimization problem to determine the retailer’s optimal ordering policies.
Further, the general assumption in classical inventory models is that the organization owns a single warehouse without capacity limitation. In practice, while a large stock is to be held, due to the limited capacity of the owned warehouse (denoted by OW), one additional warehouse is required. This additional warehouse may be a rented warehouse (denoted by RW), which is assumed to be available with abundant capacity. However, the backlogging rate in classical inventory models based on the waiting time are realistic only if the supply chain between the retailer parties and the customer parties has enabled share information through the well channel partnership.
This thesis is consisted of five chapters. In Chapter 2, we first explores a generalized inventory control system for deteriorating items with time-varying demand under advance booking discount and two-echelon trade credits. In Chapter 3, we extend Chapter 2’s model and then propose a finite time horizon inventory model for deteriorating items with time-varying demand through an ABD program. We further simplify the search process by providing an intuitively good starting value for the optimal number of replenishments and the optimal replenishment cycle time. In Chapter 4, we present a deterministic inventory model for deteriorating items with two warehouses under ABD program.
Moreover, we assume that the backorder cost per unit time is a linearly function and partial backlogging δ . The necessary and sufficient conditions of the existence and uniqueness of the optimal solutions for the three models are shown. Some numerical examples are used to illustrate the three model and conclude the thesis with suggestions for possible future research.

並列關鍵字

Inventory ； Finite planning horizon ； Time-varying demand ； Trade credit ； Advance booking discount ； Two-warehouse

參考文獻

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