Endüstri Mühendisliği Bölümü Yayın Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/279
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Article Citation - WoS: 5Citation - Scopus: 5A Blood Distribution Problem With New Transportation Options - an Application for the Turkish Red Crescent(inderscience Enterprises Ltd, 2019) Azizoglu, Meral; Kurt, Atil; Cetinkaya, Ferda CanThis paper considers the blood distribution problem in the Central Anatolian Regional Blood Centre of the Turkish Red Crescent (TRC) and proposes several demand satisfaction options considering the irradiation centres, urgent demands, and product availability. Our aim is to maximise the total weighted blood demand satisfaction. To address the problem, we develop a mixed integer linear programming model and propose a hybrid genetic algorithm (HGA). The results of our experiments have revealed that the mathematical model cannot handle even small sized problem instances in reasonable times; however, the hybrid genetic algorithm is capable of handling complex daily operations of the Turkish Red Crescent.Article Citation - WoS: 23Citation - Scopus: 35An Exact Solution Procedure for Multi-Item Two-Echelon Spare Parts Inventory Control Problem With Batch Ordering in the Central Warehouse(Elsevier Science Bv, 2010) Tan, Tarkan; Bayindir, Z. Pelin; Topan, EnginWe consider a multi-item two-echelon inventory system in which the central warehouse operates under a (Q, R) policy, and the local warehouses implement basestock policy. An exact solution procedure is proposed to find the inventory control policy parameters that minimize the system-wide inventory holding and fixed ordering cost subject to an aggregate mean response time constraint at each facility. (C) 2010 Elsevier B.V. All rights reserved.Article Citation - WoS: 5Citation - Scopus: 8Lp Relaxation-Based Solution Algorithms for the Multi-Mode Project Scheduling With a Non-Renewable Resource(inderscience Enterprises Ltd, 2015) Cetinkaya, Ferda Can; Pamir, Selin Kirbiyik; Azizoglu, MeralIn this study, we consider a multi-mode resource allocation problem with a single non-renewable resource. We assume the resource is released at defined time points and at defined quantities. We also assume that the activity costs are charged once they are completed. Our aim is to minimise the project completion time. We formulate the problem as a pure integer programming model and show that it is strongly NP-hard. We find lower bounds by pure and mixed integer linear programming relaxations of the model and develop three heuristic procedures based on those relaxations. The results of our computational study have revealed the satisfactory performances of our lower bounds and heuristic procedures.Article Minisum and maximin aerial surveillance over disjoint rectangles(2016) Karasakal, OrhanThe aerial surveillance problem (ASP) is finding the shortest path for an aerial surveillance platform that has to visit each rectangular area once and conduct a search in strips to cover the area at an acceptable level of efficiency and turn back to the base from which it starts. In this study, we propose a new formulation for ASP with salient features. The proposed formulation that is based on the travelling salesman problem enables more efficient use of search platforms and solutions to realistic problems in reasonable time. We also present a max–min version of ASP that maximizes the minimum probability of target detection given the maximum flight distance of an aerial platform. We provide computational results that demonstrate features of the proposed models.Article Citation - WoS: 4Citation - Scopus: 3Optimum Bidding Strategy for Wind and Solar Power Plants in Day-Ahead Electricity Market(Springer Heidelberg, 2021) Keysan, Ozan; Satir, Benhur; Ozcan, MehmetThere are two possible strategies for wind power plants (WPPs) and solar power plants (SPPs) to maximize their income in day ahead markets (DAM) in the presence of imbalance cost: joint bidding (JB) via collaboration by participating to balancing groups and deployment of storage technologies. There are limited studies in the literature covering the comparative analysis of "JB strategy" with "battery deployment (BD) strategy". In the existence of balancing responsibility, the comparative analysis of these strategies is the main contribution of this study to the literature. Our Second contribution is the analysis of the impact of different regulatory regimes, which are set by the regulatory authority, on total income. JBM (joint bidding model), which is the model for joint bidding via different collaboration groups, is developed for the analysis of JB strategy, BDM (battery deployment model), which is the model covering the deployment of storage technology, is developed for the analysis of BD strategy. The impact of each strategy on total income is analyzed. According to the analysis of the results of the models, while JB strategy, which is sensitive to the regulatory regime, increases the total annual income of the collaboration groups up to 0.65%, BD strategy seems not feasible and financially viable. On the other hand, extra income values per MW of battery for SPP is between $218 and $400 /MW-year, while these values are between $2460 and $6795/MW-year for the group of 15 WPPs. Therefore, deployment of battery for WPPs creates extra income more than tenfold of that of SPP. BD strategy can be viable provided that the levelized cost of deployment of battery drops below the extra income values achieved per MW of battery.Article Citation - Scopus: 7A Partial Coverage Hierarchical Location Allocation Model for Health Services(Inderscience Publishers, 2023) Karasakal, O.; Karasakal, E.; Töreyen, Ö.We consider a hierarchical maximal covering location problem (HMCLP) to locate health centres and hospitals so that the maximum demand is covered by two levels of services in a successively inclusive hierarchy. We extend the HMCLP by introducing the partial coverage and a new definition of the referral. The proposed model may enable an informed decision on the healthcare system when dynamic adaptation is required, such as a COVID-19 pandemic. We define the referral as coverage of health centres by hospitals. A hospital may also cover demand through referral. The proposed model is solved optimally for small problems. For large problems, we propose a customised genetic algorithm. Computational study shows that the GA performs well, and the partial coverage substantially affects the optimal solutions. © 2023 Inderscience Enterprises Ltd.Article A Partial Coverage Hierarchical Location Allocation Model for Health Services(inderscience Enterprises Ltd, 2023) Karasakal, Esra; Toreyen, Ozgun; Karasakal, OrhanWe consider a hierarchical maximal covering location problem (HMCLP) to locate health centres and hospitals so that the maximum demand is covered by two levels of services in a successively inclusive hierarchy. We extend the HMCLP by introducing the partial coverage and a new definition of the referral. The proposed model may enable an informed decision on the healthcare system when dynamic adaptation is required, such as a COVID-19 pandemic. We define the referral as coverage of health centres by hospitals. A hospital may also cover demand through referral. The proposed model is solved optimally for small problems. For large problems, we propose a customised genetic algorithm. Computational study shows that the GA performs well, and the partial coverage substantially affects the optimal solutions. [Submitted: 20 January 2021; Accepted: 15 January 2022]Article Citation - WoS: 6Citation - Scopus: 6Solution Approaches To the Blood Distribution Problem of the Turkish Red Crescent(inderscience Enterprises Ltd, 2018) Cetinkaya, Ferda Can; Kurt, Atil; Azizoglu, MeralThis paper considers the blood distribution problem that includes irradiation centres, urgent demands, and product availability in Turkey, Central Anatolian Regional Blood Center of the Turkish Red Crescent. To address the problem, we develop a mixed integer linear program with two objectives: maximising the demand satisfaction and minimising total time travelled by the vehicles. We propose two decomposition-based heuristic solution approaches. The results of our experiments have revealed that the model cannot solve even small sized instances in reasonable times; however, the heuristic solution approaches are appropriate for solving complex real life problems.Article Citation - WoS: 18Citation - Scopus: 18A Study on Nutrient Removal From Municipal Wastewater by Struvite Formation Using Taguchi's Design of Experiments(Mary Ann Liebert, inc, 2008) Uludag-Demirer, SibelThe aim of this study is to investigate the removal of NH4+-N and PO43--P from the municipal wastewater by struvite (MgNH4PO4.6H(2)O) formation. The optimization of the NH4+-N and PO43--P removals is made by changing the total concentrations of struvite forming ions (Mg2+, NH4+, PO43-) and pH of the wastewater. The experimental design was made using Taguchi's L-9(3(4)) orthogonal array technique in the first stage of the study. The conditions yielding maximum removals of NH4+-N and PO43--P are found as molar concentration ratio of Mg:N:P of 2:2:2 and 3:3:2, respectively, using the signal-to-noise (S/N) ratio of experimental results. The removal of NH4+-N followed the stoichiometry of struvite formation, while PO43--P removal required the excess amount of Mg2+. The pH of wastewater in which the maximum NH4+-N and PO43--P removals are observed was 9.0. All of the factors tested influenced the removal of NH4+-N opposite to the removal Of PO43--P, in which the concentration of NH4+-N was found insignificant statistically. Therefore, the addition of NH4+ ion is eliminated and Taguchi's L-4(2(3)) orthogonal array was used in the second stage of experimental study. The molar concentration ratios of struvite forming ions (Mg:N:P) were found to be as 1:1:1 and 2:1:1 for maximum NH4+-N and PO43--P removals at the levels of 52.4 and 67.7%, respectively, at pH 9.0 using the S/N ratios of experimental results. The performance of proposed method in removing NH4+-N and PO43--P and foreseen problems related with effluent quality is discussed.Article Citation - WoS: 7Citation - Scopus: 11A Warehouse Design With Containers for Humanitarian Logistics: A Real-Life Implementation From Turkey(Univ Cincinnati industrial Engineering, 2019) Sahin-Arslan, Aysenur; Ertem, Mustafa Alp; Ertem, Mustafa Alp; Endüstri MühendisliğiThe purpose of this study is to investigate how and at what cost freight containers could be used as an inventory holding mechanism for humanitarian logistics. The layout and cost comparison of two alternatives are performed-stocking in a warehouse and material storage in containers. An optimum layout for storage in containers is proposed. It was found that container stockpiling uses the available area and space better than the warehouse option to stock the same number of material pallets. Leasing and purchasing costs of these alternatives are compared using present worth analysis. The results revealed that the container leasing option is not cost effective when land cost is included. Warehouse leasing results in the least setup cost, however, it incurs more operating costs, including lighting, ventilation, and maintenance as well as handling of the pallets. A real-life implementation of the proposed container stockpiling idea is presented for Turkey.
