Browsing by Author "Ak, Deniz"

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Citation Count: 100
Supplier Selection for Framework Agreements in Humanitarian Relief
(Wiley-Blackwell, 2014) Balcik, Burcu; Ak, Deniz
In this study we consider the supplier selection problem of a relief organization that wants to establish framework agreements (FAs) with a number of suppliers to ensure quick and cost-effective procurement of relief supplies in responding to sudden-onset disasters. Motivated by the FAs in relief practice we focus on a quantity flexibility contract in which the relief organization commits to purchase a minimum total quantity from each framework supplier over a fixed agreement horizon and in return the suppliers reserve capacity for the organization and promise to deliver items according to pre-specified agreement terms. Due to the uncertainties in demand locations and amounts it may be challenging for relief organizations to assess candidate suppliers and the offered agreement terms. We use a scenario-based approach to represent demand uncertainty and develop a stochastic programming model that selects framework suppliers to minimize expected procurement and agreement costs while meeting service requirements. We perform numerical experiments to understand the implications of agreement terms in different settings. The results show that supplier selection decisions and costs are generally more sensitive to the changes in agreement terms in settings with high-impact disasters. Finally we illustrate the applicability of our model on a case study.
A supplier selection model for designing framework agreements in relief chain
(Kadir Has Üniversitesi, 2011) Ak, Deniz; Balcik, Burcu
When a disaster occurs disaster relief operations are undertaken immediately to help people affected by disasters. However in the aftermath of natural disasters relief supplies that are critical for survival may not be readily available in the desired amounts or prices. Hence procurement is an important function for disaster relief operations. Relief organizations face with several procurement decisions in managing the relief chain. Since quick response is critical in disaster relief designing efficient procurement methods are important for relief organizations. in this thesis we focus on framework agreements which allow relief organizations to guarantee availability and fast procurement of relief supplies. Given the complexities of the disaster relief operations and uncertainties regarding the occurrence of disasters designing effective framework agreements can be difficult for relief organizations. in our study we examine the characteristics of the contracts that are applied in relief chains and traditional supply chains and explore the applicability of supply chain contracts as framework agreements in relief chains. We choose a quantity flexibility contract and develop a two-stage stochastic programming model that selects suppliers to an agreement and determines some contract terms for the relief organization. We develop a case study to illustrate the implementation of the proposed model and test the effects of various parameters on solutions.