

Articles
by
Ata Allah Taleizadeh 
Total Records (
2 ) for
Ata Allah Taleizadeh 





Ata Allah Taleizadeh
,
Seyed Taghi Akhavan Niaki
and
MirBahador Aryanezhad


While in multiperiodic inventory control problems the usual assumption are that the orders are placed at the beginning of each period (periodic review) or depending on the inventory level they can happen at any time (continuous review), in this research, we relax these assumptions and assume that the periods between two replenishments of the products are independent and identically distributed random variables. Furthermore, assuming the purchasing price are triangular fuzzy variables, the quantities of the orders are of integertype and that there are space, budget and service level constraints, incremental discount is considered to purchase products and a combination of backorder and lostsales are taken into account for the shortages. We show that the model of this problem is a fuzzy mixedinteger nonlinear programming type and in order to solve it, a hybrid method of fuzzy simulation and genetic algorithm approach is used. At the end, a numerical example is given to demonstrate the applicability of the proposed methodology in real world inventory control problems. 





Ata Allah Taleizadeh
,
MirBahador Aryanezhad
and
Seyed Taghi Akhavan Niaki


Multiperiodic inventory control problems are mainly studied employing two assumptions. The first is the continuous review, where depending on the inventory level orders can happen at any time and the other is the periodic review, where orders can only happen at the beginning of each period. In this study, we relax these assumptions and assume that the periodic replenishments are stochastic in nature. Furthermore, we assume that the periods between two replenishments are independent and identically random variables. For the problem at hand, the decision variables are of integertype and there are two kinds of space and service level constraints for each product. We develop a model of the problem in which a combination of backorder and lostsales are considered for the shortages. Then, we show that the model is of an integernonlinearprogramming type and in order to solve it, a search algorithm can be utilized. We employ a simulated annealing approach and provide a numerical example to demonstrate the applicability of the proposed methodology. 





