Optimal issuing policy for fish-breeding supply center with items Weibull ameliorating

In conventional inventory models, the items are based on the assumptions that the values (or utility) of items in inventory remain constant over time, but in the most practical cases, it is not constant and changes increasing or decreasing over time. In this study, a special case of inventory model is studied for the items of which utilities are increasing over time. We develop ameliorating inventory models to find optimal issuing policy in fish-breeding supply center. The two issuing policies are considered, FIFO (first-in-first-out) and LIFO (last-in-last-out), to find optimal issuing policy. We derived the equations of inventory levels for both issuing policies, FIFO and LIFO, and we developed two ameliorating inventory models to find the economic order quantity (EOQ) and the economic selling quantity (ESQ). We developed a computer program for this research and applied it in a fish-breeding supply center problem to show the effectiveness of the proposed models. From the sensitivity analysis, we can see that the ameliorating inventory effect affects the issuing policy, EOQ and ESQ of the fishbreeding supply center significantly.