Researches On Inventory Model For Imperfect Items

In order to ensure smooth production and business activities of enterprises andcope with the uncertainty of the supply and demand, inventory is essential forevery enterprise. In real life, because of machine failures and producttransportation damages and so on, products may contain a certain defective items.In this paper we study on inventory model for imperfect items.At first, inventory model with random imperfect rate is considered. By consideringtwo types of random inspection errors, we develop the decision-making models ofinventory with (model1)and without shortages(model2). And we give the solutionprocess and derive the expression of the optimal solutions. Numerical examples arepresented and the effects of parameters on the optimal solutions are analyzed:(1) Model1is the special case of model2.(2) In this two models, when imperfect rate and type I random inspection errorincrease, the optimal order lot increases, both the order cycle and the expectedprofit decrease. When type II random inspection error increases, optimal order lotdecreases, the optimal profit decreases.(3) Comparing with the inventory model while the shortages are not allowed, theinventory with shortages indicates that optimal order lot increases and optimalprofit increases.Finally, this model is extended to the model with the perishable items. Byconsidering of no shortages, we develop EOQ model with random imperfect rateand perishable rate. Numerical examples are presented. Comparing with the S-Jmodel, the optimal order lot decreases, order increases and the optimal profitdecreases.The research results presented above enrich the content of inventory control theory,have important practice sense and provide more sufficient scientific evidences for decisionmakers making inventory decisions.