Halit Üster

Bio: Halit Üster is an academic researcher from Southern Methodist University. The author has contributed to research in topics: Network planning and design & Facility location problem. The author has an hindex of 19, co-authored 42 publications receiving 1380 citations. Previous affiliations of Halit Üster include McMaster University & Texas A&M University.

Benders decomposition with alternative multiple cuts for a multi-product closed-loop supply chain network design model

Abstract: In this article, we consider a multi-product closed-loop supply chain network design problem where we locate collection centers and remanufacturing facilities while coordinating the forward and reverse flows in the network so as to minimize the processing, transportation, and fixed location costs. The problem of interest is motivated by the practice of an original equipment manufacturer in the automotive industry that provides service parts for vehicle maintenance and repair. We provide an effective problem formulation that is amenable to efficient Benders reformulation and an exact solution approach. More specifically, we develop an efficient dual solution approach to generate strong Benders cuts, and, in addition to the classical single Benders cut approach, we propose three different approaches for adding multiple Benders cuts. These cuts are obtained via dual problem disaggregation based either on the forward and reverse flows, or the products, or both. We present computational results which illustrate the superior performance of the proposed solution methodology with multiple Benders cuts in comparison to the branch-and-cut approach as well as the traditional Benders decomposition approach with a single cut. In particular, we observe that the use of multiple Benders cuts generates stronger lower bounds and promotes faster convergence to optimality. We also observe that if the model parameters are such that the different costs are not balanced, but, rather, are biased towards one of the major cost categories (processing, transportation or fixed location costs), the time required to obtain the optimal solution decreases considerably when using the proposed solution methodology as well as the branch-and-cut approach. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007

Network design for reverse and closed-loop supply chains: An annotated bibliography of models and solution approaches

Abstract: Historically, both the theory and practice of supply chain management have placed an emphasis on manufacturing and distribution operations, i.e., the forward channel, which consists of suppliers, manufacturers, distributors, retailers, and customers. Recently, increased attention to product recovery practices has extended the scope of traditional supply chain management by drawing attention to collection, demanufacturing, and remanufacturing operations, i.e., the reverse channel, which consists of final-users, collectors, demanufacturers, and remanufacturers. To optimize the performance of the extended supply chain, there is a need to establish an effective and efficient infrastructure via optimal network design. As a result, network design for product recovery has attracted the attention of a growing number of researchers in the past decade. In an attempt to draw more academic attention to this area, this annotated bibliography provides a detailed account of the published literature. The article is organized into two main sections that focus on (i) reverse supply chain network design, which is concerned with establishing an infrastructure to manage the reverse channel only and (ii) closed-loop supply chain network design, which is concerned with establishing an infrastructure to manage both forward and reverse channels in a coordinated manner. Specifically, we describe the operational characteristics of the underlying supply chain system considered in each paper, highlight the features of the network design model proposed therein, and discuss the proposed solution approach along with a brief description of significant computational work, if available. In conclusion, a critical review of the published literature is given and potential areas for future research are identified. © 2008 Wiley Periodicals, Inc. NETWORKS, 2009

A closed-loop supply chain network design problem with integrated forward and reverse channel decisions

Abstract: This article considers a multi-product closed-loop logistics network design problem with hybrid manufacturing/remanufacturing facilities and finite-capacity hybrid distribution/collection centers to serve a set of retail locations. First, a mixed integer linear program is presented that determines the optimal solution that characterizes facility locations, along with the integrated forward and reverse flows such that the total cost of facility location, processing, and transportation associated with forward and reverse flows in the network is minimized. Second, a solution method based on Benders' decomposition with strengthened Benders' cuts for improved computational efficiencies is devised. In addition to this method, an alternative formulation is presented and a new dual solution method for the associated Benders' decomposition to obtain a different set of strengthened Benders' cuts is developed. In the Benders' decomposition framework, the strengthened cuts obtained from original and alternative formu...

Wireless Charging of Electric Vehicles in Electricity and Transportation Networks

Abstract: Wireless charging station (WCS) enables in-motion charging of the electric vehicles (EVs). This paper presents the short-term operation of WCS by capturing the interdependence among the electricity and transportation networks. In the transportation network, the total travel cost consists of the cost associated with the travel time and the cost of utilized electricity along each path. Each EV takes the path that minimizes its total travel cost. In the electricity network, the changes in WCS demand as a result of changes in the traffic flow pattern impacts the price of electricity. The changes in the price of electricity further affect the charging strategy of the EVs and the associated traffic flow pattern. The coordination between electricity and transportation networks would help mitigate congestion in the electricity network by routing the traffic flow in the transportation network. The presented formulation leverages decentralized optimization to address the economic dispatch in the electricity network as well as the traffic assignment in the transportation network. The presented case studies highlight the merit of the presented model and the developed algorithms for the coordinated operation of WCS in electricity and transportation networks.