An EPQ Model for Delayed Deteriorating Items with Variable Production Rate, Two-Phase Demand Rates and Shortages

An EPQ Model for Delayed Deteriorating Items with Two-Phase Production Period, Exponential Demand Rate and Linear Holding Cost

“…The proposed model in comparison with the existing models having the same objective and using the same data, it is discovered that the total variable cost obtained in this work is far minimum to that obtained in [ 17 , 49 ]. Similarly, the production quantity obtained in this work within a less than 1 year cycle is maximum to that obtained in [ 17 ] with a cycle of more than one and half years .…”

“…The proposed model is developed based on the following modified assumptions adopted from [ 49 ] with addition of 2, 4, 9 and 10: Instantaneous production. Instantaneous change of production rate.…”

“…The model developed in this work is illustrated by performing the following numerical experiments. Some of the parameter values presented in Table 3 are adopted from [ 17 , 49 ] in addition to the values of parameters absent in their work which were also obtained optimally.…”

“…Similarly, the production quantity obtained in this work within a less than 1 year cycle is maximum to that obtained in [ 17 ] with a cycle of more than one and half years . Also, maximum to the production quantity obtained in [ 49 ] within a cycle of more than 1 year . As such, the proposed model in this work is perfectly better.…”

“…For local products with less life span, the production rate has to be reduced to avoid losses while for globally use with longer life span products and some items that their demand is at an exponential rate (such as past-food wrapping materials, facemasks, hand wash sanitizer and so on), the production rate needs to be accelerated before these measures are imposed to avoid shortages. The production rate of this kind is conditional and little work is found where it is considered in the study of inventory systems, where it exists [ 49 , 50 ], the change in production is not instantaneous and the demand rate is not exponential. As such, this research tries to solve the production problem caused by the instantaneous sudden change in production rate by providing an EPQ model for non-instantaneous deteriorating items with conditional production rate, exponential demand rate and linearly time-dependent holding cost (Table 1 ).…”