Ata Allah Taleizadeh - Department of Industrial Engineering, Iran University of Science and Technology
Hassan Shavandi - Department of Industrial Engineering, Sharif University of Technology
Maghsoud Amiri Moghanjoughi - Department of Industrial Management, Allameh Tabatabaee University

An nucertain economic order quantity (UEOQ) midel payment in advance is developed to purchase high-price raw materials. A joint policy of replenishments and pre-peyments is employed to supply the materials. The rate of demand is considered fuzzy rough variable, lead time is divided into three parts; the first interval is the time between the previous replenishment- time cycle is divided into three (t0), the second one is the time between t0 to a payment- time (tlc), and the third interval is the period between tic to the next replenishment-time. At the beginning of the second interval (t0), a% of the purchasing cost is paid. the remaning purchazing cost ((1-a)%) is paid at the beginning of the thired pard (tlc). we show that the model of this problem is a fuzzy rough mixed integer-nonlinear -programming type and in order to solve it, a hybrid method of particle Swarm Optimization and fuzzy rough simulation is developed.

Joint Replenishment, EOQ, Particle Swarm Optimization, Fuzzy Rough Programming