Contents lists available at ScienceDirect Transportation Research Part E journal homepage: www.elsevier.com/locate/tre Robustgasolineclosedloopsupplychaindesignwithredistricting, service sharing and intra-district service transfer R. Saedinia, Behnam Vahdani ⁎ , F. Etebari, B. Afshar Nadjaf Department of Industrial Engineering, Faculty of Industrial and Mechanical Engineering, Qazvin Branch, Islamic Azad University, Qazvin, Iran ARTICLEINFO Keywords: CLSC network design Redistricting Resource sharing Service transfer Robust optimization ABSTRACT Thispaperpresentsabi-objectivemodeltodesignaclosedloopsupplychainwithsimultaneous considerationofdistrictingregions,facilitylocation–allocation,servicesharing,andintra-district servicetransfer.The frstobjective functionistominimizethetotalcosts,andthesecondoneisto minimize the maximum volume of surplus demand from service facilities. In this model, costs, returns, and maximum service supply are uncertain; a robust optimization approach is used to takeintoaccounttheuncertainty.Additionally,thevalidityoftheproposedmathematicalmodel on a real case study in the oil and gas industry sector has been investigated. 1. Introduction Therapideconomicchangesandincreasedcompetitivepressuresinglobalmarketshavepersuadedcompaniestoemphasizethe importanceofsupplychainandintegratedlogistics(Kalaitzidou et al., 2015). In addition, considering environmental concerns and social responsibilities, an increasing number of companies have applied reverse logistic approaches and forward supply chains (Zeballosetal.,2014),makingreverselogisticsandclosedloopsupplychains(CLSCs)asthetwosignifcantaspectsofeveryindustry. Currently, governmental rules alongside green supply chain management, active in recovering and exterminating the wastes and otherdangerousproducts,forcestopmanagerstopayattentiontoandreconsidertheprocessesinsupplychainnetworks(Vahdani and Mohammadi, 2015). Inthiscontext,thedemandbeyondthecapacityoftheserviceprovidersisoneofthecriticalissuesindecidingwhethertoprovide service for customers or to facilitate the supply chain networks (SCNs), owing to their signifcant impact on ofering high-quality services(Jasmandetal.,2012).Therefore,itcanbearguedthattheseserviceprovidersfacealackofcapacityinrespondingtothe demand.Thisdefciencyisgenerallyduetothe factthatserviceproviderstypicallyconsiderthelowcapacityinprovidingservicefor theircustomers,whoareinturnafectedbyunfavorableconditionsandeconomicstagnation(Yangetal.,2003).Moreover,sinceitis impossibleforserviceproviderstoincreasecapacityovertheplanninghorizon,theneedtousealternativeandefectiveapproaches inSCNsisessential.Oneoftheseefective approaches is the use of the spatial disparity model (Koetal.,2015). Districtingisdefnedasclusteringtogethertheregionsofcustomersasservicelocationsanddemandunits,inawaythatcanlead to better customer service quality and to increased customer satisfaction. The advantage of districting that balances the volume of demandintheregionsisintra-districtservicetransfer(Duqueetal.,2012),whichisusedtodeterminehowtoshareservicecapacity within each district. This sharing occurs through the transfer of surplus services at those facilities that have capacity surplus. Therefore, in addition to balancing demand among districts, district service transfer makes the workload of service facilities within eachdistrictwell-adjusted.Itshouldbenotedthattheprocessisessentialformaximizingtheefcientusageofservicecapacitiesand https://doi.org/10.1016/j.tre.2019.01.015 Received 19 July 2018; Received in revised form 16 December 2018; Accepted 29 January 2019 ⁎ Corresponding author. E-mail address: b.vahdani@gmail.com (B. Vahdani). Transportation Research Part E 123 (2019) 121–141 1366-5545/ © 2019 Elsevier Ltd. All rights reserved. T