Among the assumptions of the classical economic order quantity (EOQ) model is that all units that are purchased (or produced) are of perfect quality. However, this is frequently unrealistic since production processes deteriorate resulting in the production of defective products requiring rework. Some recent studies suggest that production systems performance might be improved by applying the fi...

It was suggested in 2004 by some researchers that it might be possible to improve production systems performance by applying the first and second laws of thermodynamics to reduce system entropy. Then these laws were used to modify the economic order quantity (EOQ) model to derive an equivalent entropic order quantity (EnOQ). Moreover the political instability or uncertainty of a country (as wel...

In practice the items received in a lot may contain defective items, and the screening process to eliminate the defective items may involve both a Type I and a Type II error. Due to the defective items and the inspection errors, shortages may sometimes occur. In this paper, we develop an economic order quantity model with imperfect quality items, inspection errors, shortage backordering, and sa...

In this paper, we develop an economic production quantity (EPQ) model under machine breakdown and two types of repair (corrective and preventive). also, study the simultaneous effect of holding safety stock and purchasing policy. In order to avoid shortages occurring as a result of the random repair time, in addition to keep safety stock, we suppose that the manufacturer could purchase some qua...

The classic Economic Order Quantity model assumes that an order is paid for at the time of its receipt. In practice, suppliers may require purchasers to pay a fraction of the order’s cost in advance and sometimes allow them to divide the prepayment into multiple equalsized parts to be paid during a fixed lead time. In this paper, an EOQ model with multiple prepayments under three different cond...