Seminar: A deterministic model for the transshipment problem of a fast fashion retailer under capacity constraints by Siamak Naderi

Department of Industrial Engineering 
A deterministic model for the transshipment problem of a fast fashion retailer under capacity constraints 
Siamak Naderi 
Faculty of Engineering and Natural Sciences, Sabancı University


In this paper we present a novel transshipment problem for a large apparel retailer that operates an extensive retail network. Our problem is inspired by the logistics operations of a very large fast fashion retailer in Turkey, LC Waikiki, with over 475 retail branches and thousands of products. The purpose of transshipments is to rebalance stocks across the retail network to better match supply with demand. We formulate this problem as a large mixed integer linear program and develop a Lagrangian relaxation with a primal–dual approach to find upper bounds and a simulated annealing based metaheuristic to find promising solutions, both of which have proven to be quite effective. While our metaheuristic does not always produce better solutions than a commercial optimizer, it has consistently produced solutions with optimality gaps lower than 7% while the commercial optimizer may produce very poor solutions with optimality gaps as high as almost 300%. We have also conducted a set of numerical experiments to uncover implications of various operational practices of LC Waikiki on its system’s performance and important managerial insights.
Short Bio: 

Siamak Naderi is a Ph.D. candidate in the Industrial Engineering program of Sabanci University. He received his BS, 2011, and MSc, 2014 degrees in Industrial Engineering from University of Tehran in Tehran, Iran, and Sabanci University in Istanbul, Turkey, respectively. His research interests are largely related to developing algorithms for large scale Mixed Integer Programming models,  particularly for the models motivated by real-life problems with specific business rules. Currently, he collaborates with LC Waikiki on developing algorithms for transshipment, return, and discount decisions. He also teaches Decision Analysis and Operations Research courses in the Industrial Engineering program of Sabanci University. 

Date: Wednesday, June 17, 2020
Time: 15:00-16:00
Online Seminar Link:
Topic: IE Department Seminar, Speaker: Dr. Siamak Naderi
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Meeting ID: 940 5560 7080