Uncertainty theory has got quite attention after it was pioneered by Baoding Liu in 2007. Uncertainty is the newest area among the concepts to express imprecise quantities which can be expressed by the ambiguity of human language. Such an unpredictable value can be neither accurately described by probability theory nor fuzzy logic. In inventory models, costs are very prominent part of the syste...

Imperfect quality items are unavoidable in an inventory system due to imperfect production process, natural disasters, damages, or many other reasons. The setup cost and production cycle time can be related in terms of process deterioration and learning and forgetting effects. Learning reduces production run length and setup cost, whereas deterioration and forgetting increases both. Keeping the...

it is assumed in most of the existing models that the items can be stored for an unlimited time to meet the future’s demand and their quality and quantity does not change during that period. nevertheless there are special kinds of products which deteriorate or become unusable (such as food products, alcohol, medicines, etc.). therefore if the rate of deterioration is significantly high, the imp...

Many companies use time as a means of differentiating themselves in the marketplace. In many literatures, the controllable lead time is regarded as a decision variable and decomposed into several components, each having a crashing cost function for the respective reduced lead time. When an item is out of stock, the loyal, patient and captive customers will wait until the outstanding orders arri...

The traditional inventory of the economic order quantity model assumes perfect items in an ordered lot and an infinite replenishment rate. However, such conditions are rare in actual production environments. Additionally, most studies of this problem have only considered suppliers offering the wholesaler a grace period. In practice, wholesalers often extend a fixed credit period to downstream c...