میزان زیاد تولید با تسهیلات برون سپاری ثانویه
|کد مقاله||سال انتشار||مقاله انگلیسی||ترجمه فارسی||تعداد کلمات|
|668||2013||11 صفحه PDF||سفارش دهید||10050 کلمه|
Publisher : Elsevier - Science Direct (الزویر - ساینس دایرکت)
Journal : International Journal of Production Economics, Volume 141, Issue 1, January 2013, Pages 414–424
An extended economic production quantity (EPQ) model under stochastic demand is investigated in this paper, where a fixed lot sizing policy is implemented to reduce the complexity of production planning and inventory control, and outsourcing with a secondary facility is used to supplement the lot sizing policy and to cope with the random demand. The considered cost includes: setup cost for the batch production, inventory carrying cost, backorder cost when the demand cannot be met immediately during the production period, and outsourcing cost when the total demand is greater than the lot size in one replenishment cycle. Under some mild conditions, the expected cost per unit time can be shown to be convex. Extensive computational tests have illustrated that the average cost reduction of the proposed model is significant when compared with that of the classical lot sizing policy. Significant cost savings can be achieved by deploying the production lot sizing policy with an outsourcing strategy when the mean demand rate is high.
In the well-known Economic Production Quantity (EPQ) problem (Hadley and Whitin, 1963), one item is produced with constant production rate to meet the customer’s demand, where the demand rate is assumed finite and constant. Each replenishment cycle in EPQ consists of two stages: the duration to produce a fixed lot size, and the duration to deplete remaining inventory before a new batch is launched. When the remaining inventory drops to zero, a new replenishment cycle will resume; that is, every replenishment cycle is identical. This fixed lot size policy is widely implemented for the production-manufacturing operations. More recently, Cárdenas-Barrón (2001) studied an EPQ model where the control policy is extended to determine both the maximum backorder level (amount of shortage or the lowest inventory level) prior to production and the maximum inventory level just after the production. Since demand is a deterministic constant, the amount of shortage is fixed at the maximum backorder level in every replenishment cycle, i.e., the system is active only when the inventory (negative level) drops to the maximum backorder level. Later, Ronald et al. (2004) developed an improved algebraic method to determine the two decision variables for this extended model. For a similar EPQ model, Sphicas (2006) found that if the backorder cost is relatively large, the classical EPQ is the optimal solution, i.e., the amount of backorder is small or negligible. When backorder cost is sufficiently small, it is more cost effective to consider the maximum backorder level. Pentico et al. (2009) further extended the above study to consider the case where a fixed percentage of shortage can be treated as lost sale.
نتیجه گیری انگلیسی
An extended lot sizing policy for a production system with a secondary outsourcing facility is studied, where demand is random and outsourcing is used to meet the unsatisfied demand. The expected production inventory cost model has been developed and analyzed. Additional analytic result also indicates that the expected cost per unit time is likely to be convex with respect to the lot size. An efficient solution procedure is developed to determine the optimal lot sizing policy. Extensive computational study has illustrated the effectiveness of the proposed model, when demand is random and a secondary outsourcing facility can be supplemented to determine the production lot sizing policy. The outsourcing strategy significantly reduces the operating cost in a production system when faced with demand fluctuation. The proposed lot sizing policy clearly outperforms the classical EPQ model when the demand rate and the outsourcing cost are high. The proposed lot sizing policy serves as a basis for further advanced studies, such as a more complicated lot sizing policy with safety stock, different shortage measures or service levels, or other types of random demand processes. Production lot sizing models with reserved stock or safety stock, such as re-setup point, may be considered to reduce the backorder cost and outsourcing cost when the product can be made and stocked before the order is received. This will be the subsequent topic of the current research.