Browsing Faculty of Engineering by OzU Authors "Ekici, Ali"
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An application of unrelated parallel machine scheduling with sequence-dependent setups at Vestel Electronics
Ekici, Ali; Elyasi, Milad; Özener, Okan Örsan; Sarıkaya, M. B. (Elsevier, 2019-11)In this paper, we analyze a variant of the unrelated parallel machine scheduling problem with the objective of minimizing the total tardiness and earliness in the presence of sequence-dependent setups, unequal release ... -
Bin packing problem with conflicts and item fragmentation
Ekici, Ali (Elsevier, 2021-02)In this paper, we study the Bin Packing Problem with Conflicts and Item Fragmentation (BPPC-IF) which has applications in the delivery and storage of items that cannot be packed together. Given a set of items each with a ... -
Blood supply chain management and future research opportunities
Ekici, Ali; Özener, Okan Örsan; Göktürk, Elvin Çoban (Springer, 2018)In this chapter, we discuss the challenges and research opportunities in the blood collection operations and explore the benefits of recent advances in the blood donation process. According to the regulations, donated blood ... -
Coordinating collection and appointment scheduling operations at the blood donation sites
Mobasher, A.; Ekici, Ali; Özener, Okan Örsan (Elsevier, 2015-09)According to the regulations imposed by the U.S. Food and Drug Administration and the American Association of Blood Banks, in order to extract platelets, donated blood units have to be processed at a processing center ... -
Cyclic delivery schedules for an inventory routing problem
Ekici, Ali; Özener, Okan Örsan; Kuyzu, G. (Informs, 2015-11)We consider an inventory routing problem where a common vendor is responsible for replenishing the inventories of several customers over a perpetual time horizon. The objective of the vendor is to minimize the total cost ... -
Cyclic ordering policies from capacitated suppliers under limited cycle time
Ekici, Ali; Özener, Okan Örsan; Duran, S. (Elsevier, 2019-02)In this paper, we study the ordering policy of a manufacturer/retailer which procures a single item from multiple capacitated suppliers and satisfies an exogenous deterministic and constant demand. Manufacturer's objective ... -
Dynamic facility location with supplier selection under quantity discount
Emirhüseyinoğlu, Görkem; Ekici, Ali (Elsevier, 2019-08)Retailers have to consider several factors when making facility location decisions including suppliers' and customers' locations, customer demand and price offered by suppliers. In this study, we analyze the multi-period ... -
Genetic algorithms and heuristics hybridized for software architecture recovery
Elyasi, Milad; Simitcioğlu, Muhammed Esad; Saydemir, Abdullah; Ekici, Ali; Özener, Okan Örsan; Sözer, Hasan (Springer, 2023-06-26)Large scale software systems must be decomposed into modular units to reduce maintenance efforts. Software Architecture Recovery (SAR) approaches have been introduced to analyze dependencies among software modules and ... -
Humanitarian relief distribution problem: an adjustable robust optimization approach
Avishan, Farzad; Elyasi, Milad; Yanıkoğlu, İhsan; Ekici, Ali; Özener, Okan Örsan (Informs, 2023-03-23)Management of humanitarian logistics operations is one of the most critical planning problems to be addressed immediately after a disaster. The response phase covers the first 12 hours after the disaster and is prone to ... -
Humanitarian relief supplies distribution: an application of inventory routing problem
Çankaya, Emre; Ekici, Ali; Özener, Okan Örsan (Springer, 2019-12)In this paper, we study the distribution of humanitarian relief supplies. In humanitarian relief, supplies including food, water and medication are received in batches/waves from the suppliers and the donors. Then, these ... -
HYGAR: a hybrid genetic algorithm for software architecture recovery
Elyasi, Milad; Simitcioğlu, Muhammed Esad; Saydemir, Abdullah; Ekici, Ali; Sözer, Hasan (ACM, 2022)Genetic algorithms have been used for clustering modules of a software system in line with the modularity principle. The goal of these algorithms is to recover an architectural view in the form of a modular structural ... -
Improving blood products supply through donation tailoring
Özener, Okan Örsan; Ekici, Ali; Göktürk, Elvin Çoban (Elsevier, 2019-02)Recent technological advances, called Multicomponent Apheresis, allow tailoring the blood donations based on the demand and current inventory levels of blood products. Different from the most common type of blood donation ... -
Integrated blood collection and appointment scheduling
Mobasher, A.; Ekici, Ali; Özener, Okan Örsan (Institute of Industrial Engineers, 2012)Considering the processing requirements of donated blood, we study an integrated blood collection and appointment scheduling problem. We develop a mixed integer programming model to maximize the amount of donated blood ... -
Inventory routing for the last mile delivery of humanitarian relief supplies
Ekici, Ali; Özener, Okan Örsan (Springer Nature, 2020-09)Fast and equitable distribution of the humanitarian relief supplies is key to the success of relief operations. Delayed and inequitable deliveries can result in suffering of affected people and loss of lives. In this study, ... -
A large neighborhood search algorithm and lower bounds for the variable-sized bin packing problem with conflicts
Ekici, Ali (Elsevier, 2023-08-01)In this paper, we study the Variable-Sized Bin Packing Problem with Conflicts (VSBPPC). In VSBPPC, a set of items each with a certain size has to be packed into bins of various types. Bin types differ in terms of their ... -
Managing platelet supply through improved routing of blood collection vehicles
Özener, Okan Örsan; Ekici, Ali (Elsevier, 2018-10)In this paper, we study the routing of blood collection vehicles for improving the platelet supply in the blood supply chain. In order to extract platelets, donated blood has to be processed at a central processing facility ... -
Modeling influenza pandemic and planning food distribution
Ekici, Ali; Keskinocak, P.; Swann, J. L. (Informs, 2014)Based on the recent incidents of H5N1, H1N1, and influenza pandemics in history (1918, 1957, and 1968) experts believe that a future influenza pandemic is inevitable and likely imminent. Although the severity of influenza ... -
Pricing decisions in a strategic single retailer/dual suppliers setting under order size constraints
Ekici, Ali; Özener, Başak Altan; Özener, Okan Örsan (Informa Group, 2016)In this paper, we study a duopolistic market of suppliers competing for the business of a retailer. The retailer sets the order cycle and quantities from each supplier to minimize its annual costs. Different from other ... -
Stochastic production planning with flexible manufacturing systems and uncertain demand: A column generation-based approach
Elyasi, Milad; Özener, Başak Altan; Ekici, Ali; Özener, Okan Örsan; Yanıkoğlu, İhsan (Elsevier, 2022)The ongoing pandemic, namely COVID-19, has rendered widespread economic disorder. The deficiencies have delayed production at manufacturers in several industries on the supply side. The effects of disruption were more ... -
Supplier selection and order allocation in the presence of suppliers with exact annual capacity
Ekici, Ali; Özener, Okan Örsan; Elyasi, Milad (Inderscience Enterprises Ltd., 2021)In this paper, we focus on the supplier selection and order quantity allocation for a single retailer. The retailer orders a product from multiple suppliers with capacities, adds value to the product and fulfils the demand ...
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