• The location-allocation problem of drone base stations 

  Çiçek, Cihan Tuğrul; Gültekin, Hakan; Tavlı, Bülent (Elsevier Ltd, 2019)

  In this study, we consider the 3D location problem of multiple Drone Base Stations (DBSs) together with the allocation of the resources to serve the users in a wireless communication network. The problem is formulated as ...
• Thorax CT Dose Reduction Based on Patient Features: Effect of Patient Characteristics on Image Quality and Effective Dose 

  Koc, Gizem  | |  Koc, Zafer | | Kaniyev, Tahir | | Kokangul, Ali (Lippincott Williams and Wilkins, 2019)

  Computed tomography (CT) radiation dose reduction is vital without compromising image quality. The aim was to determine the effects of patient characteristics on the received radiation dose and image quality in ...
• A fix-and-optimize heuristic for the integrated fleet sizing and replenishment planning problem with predetermined delivery frequencies 

  Dastjerd, Niousha Karimi; Ertoğral, Kadir (Elsevier Ltd, 2019)

  In this study, we tackle an integrated fleet sizing and replenishment planning problem in a vendor managed inventory system. There is a set of customers whose inventory must be replenished using a given set of predetermined ...
• Statistical distributions and reliability functions with type-2 fuzzy parameters 

  Khaniyev, Tahir; Başkır, M. Bahar; Gökpınar, Fikri; Mirzayev, Farhad (Polish Academy of Sciences Branch Lublin, 2019)

  Type-2 fuzzy sets were initially given by Zadeh as an extension of type-1 fuzzy sets. There is a gnawing interest in type-2 fuzzy set and its memberships (named secondary memberships) to handle the uncertainty in type-1 ...
• An Adaptive Tabu Search Algorithm for Market Clearing Problem in Turkish Day-Ahead Market 

  Kurt, Nermin Elif; Şahin, H. Bahadır; Derinkuyu, Kürşad (IEEE Computer Society, 2018)

  In this study, we focus on the market clearing problem of Turkish day-ahead electricity market. We propose a mathematical model by extending the variety of bid types for different price regions. The commercial solvers may ...
• Limit theorem for a semi - Markovian stochastic model of type (s,S) 

  Hanalioğlu, Zülfiye; Khaniyev, Tahir (Hacettepe University, 2019)

  In this study, a semi-Markovian inventory model of type (s,S) is considered and the model is expressed by means of renewal-reward process (X(t)) with an asymmetric triangular distributed interference of chance and delay. ...
• Inventory model of type (s, S) under heavy tailed demand with infinite variance 

  Kamışlık, Aslı Bektaş; Kesemen, Tülay; Khaniyev, Tahir (Brazilian Statistical Association, 2019)

  In this study, a stochastic process X(t), which describes an inventory model of type (s, S) is considered in the presence of heavy tailed demands with infinite variance. The aim of this study is observing the impact of ...
• Optimization of the regional allocation of wind power capacity 

  İnanç, Burcu Cansu  ;   Ertogral, Kadir ;   Derinkuyu, Kürşad (IEEE, )

  With the growing impact of global warming and depletion of fossil fuels, the necessity of renewable energy resources is becoming more and more obvious. However, investing in intermittent renewable resources, such as wind ...
• An integrated production scheduling and workforce capacity planning model for the maintenance and repair operations in airline industry 

  Ertoğral, Kadir; Öztürk, Fatma Sedanur (Elsevier Ltd, 2019)

  Maintenance, repair, and overhaul (MRO) activities for the airline sector are generally subject to some regulations to ensure the safety and the continuity of flights. The critical equipment on aircraft must go through MRO ...
• Improving post-disaster road network accessibility by strengthening links against failures 

  Yücel, Eda; Salman, F.Sibel; Arşık, İdil (Elsevier B.V., 2018)

  We study a network improvement problem to increase the resilience of a transportation network against disasters. This involves optimizing pre-disaster investment decisions to strengthen the links of the network structurally. ...
• Energy conscious scheduling of a material handling robot in a manufacturing cell 

  Gürel, Sinan; Gültekin, Hakan; Akhlaghi, Vahid Eghbal (Elsevier Ltd, 2019)

  In cyclic scheduling of material handling robots in manufacturing cells, a common approach is to minimize the cycle time objective, which is a measure of the throughput of the cell. In a typical robot move cycle, robot ...
• Synergy-based Bidding Method for Simultaneous Freight Transportation Auctions 

  Olcaytu, E.; Kuyzu, Gültekin (Elsevier B.V., 2018)

  The tremendous use of the Internet has led freight transportation procurement websites to become an effective marketplaces that bring together several carriers and shippers. These websites enable transportation of goods ...
• Cyclic scheduling of parts and robot moves in m-machine robotic cells 

  Gültekin, Hakan; Çoban, Betül; Akhlaghi, Vahid Eghbal (Elsevier Ltd, 2018)

  We consider a flow shop type manufacturing cell consisting of m machines and a material handling robot producing multiple parts. The robot transfers the parts between the machines and loads/unloads the machines. We consider ...
• Approximation formulas for the moments of the boundary functional of a Gaussian random walk with positive drift by using Siegmund's formula 

  Gökpınar, F.; Khaniyev, Tahir A.; Aliyev, Rt (Taylor and Francis Inc., 2019)

  In this study, a boundary functional () are mathematically constructed for a Gaussian random walk (GRW) with positive drift beta and first four moments of the functional are expressed in terms of ladder variables based on ...
• UAV Base Station Location Optimization for Next Generation Wireless Networks: Overview and Future Research Directions 

  Çiçek, Cihan Tuğrul; Gültekin, Hakan; Tavlı, Bülent; Yanıkömeroğlu, Halim (Institute of Electrical and Electronics Engineers Inc., 2019)

  Unmanned aerial vehicles mounted base stations (UAV-BSs) are expected to become one of the significant components of the Next Generation Wireless Networks (NGWNs). Rapid deployment, mobility, higher chances of unobstructed ...
• The location-allocation problem of drone base stations 

  Çicek, Cihan Tuğrul; Gültekin, Hakan; Tavlı, Bülent (Elsevier Ltd, 2019)

  In this study, we consider the 3D location problem of multiple Drone Base Stations (DBSs) together with the allocation of the resources to serve the users in a wireless communication network. The problem is formulated as ...
• Bid price optimization for truckload carriers in simultaneous transportation procurement auctions 

  Kuyzu, Gültekin; Akyol, Cagla Gul; Ergun, Ozlem; Savelsbergh, Martin (Pergamon-Elsevier Science Ltd, 2015-03)

  We study simultaneous transportation procurement auctions from a truckload carrier's perspective. We formulate a stochastic bid price optimization model aimed at maximizing the carrier's expected profit. The model accounts ...
• Cyclic Delivery Schedules for an Inventory Routing Problem 

  Ekici, Ali; Ozener, Okan Orsan; Kuyzu, Gültekin (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 ...
• Pure cycles in two-machine dual-gripper robotic cells 

  Gültekin, Hakan; Dalgic, Ozden O.; Akturk, M. Selim (Pergamon-Elsevier Science Ltd, 2017-12)

  We consider a robotic cell served by a dual-gripper robot that consists of identical CNC machines placed linearly and a material handling robot loading/unloading the machines and transporting the parts between them. Identical ...
• A production scheduling model and analysis for the maintenance repair and overhaul service providers 

  Ertoğral, Kadir; Erkoc, Murat; Ulker, Dogukan Hazar (Gazi Univ, Fac Engineering Architecture, 2015)

  Maintenance, repair and overhaul (MRO) are regulated and necessary activities for the airline sector to ensure the safety and continuity of flights. Both military and commercial aircrafts must go through MRO at regulated ...

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