* Corresponding author. E-mail: bhuniaak@rediffmail.com, aakbarshaikh@gmail.com (A. K. Bhunia) © 2013 Growing Science Ltd. All rights reserved. doi: 10.5267/j.ijiec.2013.01.004 International Journal of Industrial Engineering Computations 4 (2013)241–258 Contents lists available at GrowingScience International Journal of Industrial Engineering Computations homepage: www.GrowingScience.com/ijiec A two warehouse deterministic inventory model for deteriorating items with a linear trend in time dependent demand over finite time horizon by Elitist Real-Coded Genetic Algorithm A.K. Bhunia a* , Ali Akbar Shaikh a , A.K. Maiti b and M.Maiti b a Department of Mathematics, University of Burdwan, Burdwan-713104, W.B., India b Department of Applied Mathematics, Vidyasagar University, Midnapore-721102, W.B., India C H R O N I C L E A B S T R A C T Article history: Received September252012 Received in revised format December 28 2012 Accepted January2 2013 Available online 5January 2013 This paper deals with a deterministic inventory model developed for deteriorating items having two separate storage facilities (owned and rented warehouses) due to limited capacity of the existing storage (owned warehouse) with linear time dependent demand (increasing) over a fixed finite time horizon. The model is formulated with infinite replenishment and the successive replenishment cycle lengths are in arithmetic progression. Partially backlogged shortages are allowed. The stocks of rented warehouse (RW) are transported to the owned warehouse (OW) in continuous release pattern. For this purpose, the model is formulated as a constrained non-linear mixed integer programming problem. For solving the problem, an advanced genetic algorithm (GA) has been developed. This advanced GA is based on ranking selection, elitism, whole arithmetic crossover and non-uniform mutation dependent on the age of the population. Our objective is to determine the optimal replenishment number, lot-size of two-warehouses (OW and RW) by maximizing the profit function. The model is illustrated with four numerical examples and sensitivity analyses of the optimal solution are performed with respect to different parameters. © 2013 Growing Science Ltd. All rights reserved Keywords: Inventory management Two-storage Deterioration Genetic algorithm Partial backlogging Finite time horizon 1. Introduction In the existing literature, it is found that the classical inventory models generally deal with a single storage facility. The basic assumption in these models is that the management owned a storage with unlimited capacity. In the field of inventory management, this is not always true. When an attractive price discount for bulk-purchase is available or the cost of procuring goods is higher than the other inventory related costs or there are some problems in frequent procurement or the demand of items is very high, management then decides to purchase a huge quantity of items at a time. These items cannot be stored in the existing storage viz., the owned warehouse (OW) with limited capacity. Then for storing the excess items, one (sometimes more than one) additional warehouse is hired on a rental basis. This rented warehouse (RW) may be located near the OW or a little away from it. It is generally assumed that the holding cost in RW is greater than the same as in OW. Hence, the items are stored