Lot-size System Research Articles

An inventory model for perishable items in a lot-size system with quantity discounts

An inventory model continuous in units and time is developed for perishable items in a lot-size system that allows partially backlogging and partially lost saling. The model is developed under deterministic demand, instantaneous delivery with quantity discounts, and any well-behaved probability distribution for the time to perishables. An example is given to illustrate the model.

On reducing excessive stock in the order-level lot-size system for decaying inventories

On reducing excessive stock in the order-level lot-size system for decaying inventories

The Maximum Value of Inventory and Shortages in Production Lot Size Systems

Abstract This paper proposes methods of finding the maximum value of the inventory (MVI), the maximum storage space (MSS), and the maximum value of shortages (MVS) in the production lot size system, where several products are being made on a single facility with repetitive common cycle length. Noting the fact that the MVI, MSS and MVS depend on the slack (idle) times between the production runs of two consecutive products, linear programming formulations are presented to determine the minimum MVI, the minimum MSS and the minimum MVS. In addition, when there are restrictions or upper limits on some or all of these measures, linear programming formulations are developed to obtain the constrained optimal lot sizes.

Inventory returns and special sales in a lot-size system with constant rate of deterioration

The problem of returning or of selling the inventory excess to optimal stock level is considered for deteriorating items. Two inventory models, viz. the infinite and the finite horizon models, are developed, in which the deterioration is assumed to be a constant fraction of the on hand inventory. Both the models are developed under the assumptions of instantaneous delivery and no shortages. When there is no deterioration, the developed models are related to the corresponding inventory models for non-deteriorating items. Examples are given to illustrate the derived results.

The effects of inflation and the time value of money on some inventory systems

Abstract The effects of inflation and the time value of money on the optimal policies of the order-level system and the economic lot-size system are examined. Two different inflation rates, one for the internal and the other for the external costs, are assumed. The objective is to minimize the present value of the total costs per unit time.

Optimal issuing policy in production lot size system for items with Weibull deterioration

Abstract The effect of two issuing policies, LIFO and FIFO, on the inventory level in a production lot size model for items with varying rate of deterioration is studied An implicit form of inventory level under each policy is developed for each phase of a cycle which is shown to be consistent with known extreme cases A numerical solution procedure employing the Runge-Kutta method and Simpson's Rule is developed to select a preferable policy in terms of the amount deteriorated per unit time.