دیدگاه درباره "سیاست های موجودی بهینه همراه با دریافت غیر آنی تحت اعتبار تجاری اویانگ، تنگ، چوانگ و چوانگ"

Ouyang et al. [2005. International Journal of Production Economics 98, 290–300] develop an inventory model with non-instantaneous receipt under trade credit, in which the supplier provides not only a permissible delay but also a cash discount to the retailer. They establish a criterion to find the optimal order cycle such that the total relevant cost per unit time is minimized. Although their inventory model is correct and interesting, their solution procedure has shortcomings such that it cannot locate all optimal order cycles. So, the main purpose of this paper will remove the shortcoming of Ouyang et al. (2005) and present a solution procedure to search for the entirely optimal order cycles. Furthermore, this paper reveals an example to show that Ouyang et al.'s (2005) solution procedure does not work for locating the optimal order cycle to that example, however, our solution procedure does. In sum, this paper improves Ouyang et al. (2005).

The traditional economic order quantity model assumes that an entire order is received into the inventory at one time (i.e. infinite replenishment rate). In empirical observations, the order quantity is frequently received gradually over time and the inventory level is depleted at the same time it is being replenished. Ouyang et al. (2005) think that this version of the economic order quantity (EOQ) model is known as the non-instantaneous receipt (i.e. finite replenishment rate) model. The “non-instantaneous receipt” and economic production quantity (EPQ) are the same in the mathematical model. However, there is a slight different in managerial implication. The “instantaneous receipt” means that the retailer receives the order quantity and sales at the same time in the retailer business. The EPQ means that the manufacturer produces the products and sales at the same time in the manufacturing industry. The concept of “instantaneous receipt” can be observed in Jaber et al. (2008), Liao (2008), Ouyang et al. (2008) and Yoo et al. (2009). The inventory problem consists of two parts: (1) the modeling, and (2) the solution procedure. The modeling can provide insight to solve the inventory problem and the solution procedure involves the implementation of the inventory model. From the viewpoint of practice, the modeling and the solution procedure are equally important. Ouyang et al. (2005) develop an inventory model with non-instantaneous receipt under trade credit, in which the supplier provides not only a permissible delay but also a cash discount to the retailer. They establish a criterion to find the optimal order cycle so that the total relevant cost per unit time is minimized. Although their inventory model is correct and interesting, their solution procedure has shortcomings such that it cannot locate all optimal order cycles. So, the main purpose of this paper will remove the shortcoming of Ouyang et al. (2005) and present a solution procedure to search for the entirely optimal order cycles. Furthermore, this paper reveals an example to show that Ouyang et al. (2005) solution procedure does not work for locating the optimal order cycle to that example, however, our solution procedure does. In sum, this paper improves Ouyang et al. (2005).

Based on Eqs. (32) and (33), all relations about Δ1Δ1, Δ2Δ2, Δ3Δ3 and Δ4Δ4 can be divided into six situations as follows: (i) Δ2>0Δ2>0 (namely, Δ1>0Δ1>0, Δ2>0Δ2>0, Δ3>0Δ3>0 and Δ4>0Δ4>0). (ii) Δ1>0Δ1>0, Δ2≤0Δ2≤0 and Δ4>0Δ4>0 (namely, Δ1>0Δ1>0, Δ2≤0Δ2≤0, Δ3>0Δ3>0 and Δ4>0Δ4>0). (iii) Δ1≤0Δ1≤0 and Δ4>0Δ4>0 (namely, Δ1≤0Δ1≤0, Δ2<0Δ2<0, Δ3>0Δ3>0 and Δ4>0Δ4>0). (iv) Δ1>0Δ1>0 and Δ4≤0Δ4≤0 (namely, Δ1>0Δ1>0, Δ2<0Δ2<0, Δ3>0Δ3>0 and Δ4≤0Δ4≤0). (v) Δ1≤0Δ1≤0, Δ3>0Δ3>0 and Δ4≤0Δ4≤0 (namely, Δ1≤0Δ1≤0, Δ2<0Δ2<0, Δ3>0Δ3>0 and Δ4≤0Δ4≤0). (vi) Δ3≤0Δ3≤0 (namely, Δ1<0Δ1<0, Δ2<0Δ2<0, Δ3≤0Δ3≤0 and Δ4<0Δ4<0). These six situations (i)–(vi) can be treated as criteria to search for the optimal order cycle. The entirely optimal order cycle can be obtained by applying for one of criteria. Section 6 in this paper reveals an example to show that the solution procedure of Ouyang et al. (2005) does not work for locating the optimal order cycle to that example. Consequently, this paper improves Ouyang et al. (2005).