Browsing by Author "S. Erol"

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    A New Solution Approach for Optimizing the Integrated Airline Scheduling Problem in The Management of Irregular Operations
    (2023-01-01) Güner, Gürkan Güven; S. Erol
    Objective ⎯ The aim of this study is; for airline companies that have incurred unprecedented costs in the aviation sector due to the global pandemic that has emerged unexpectedly today; in order to solve the problem of flight, aircraft and crew scheduling that they have to reschedule within a very short time frame within the scope of the management of irregular events; to propose a method that can produce solutions with an integrated optimization approach, and to be able to advise decision makers in the airline sector on cost management and to contribute to the literature on airline management. Design / Methodology / Approach ⎯ Within the scope of the study, all the existing optimization solution approaches proposed for airline scheduling problems in the literature were tried to be examined and analyzed. The ways in which the studies handled airline scheduling problems discretely or integratedly, the mathematical optimization models they proposed and the heuristic/meta-heuristic methods used were reported. In the light of the data obtained after a comprehensive literature research, a new mathematical model using mixed integer nonlinear programming is proposed for the integrated airline scheduling problem. Whether the proposed mathematical model could solve a small-sized airline scheduling problem was tested through GAMS software. In order to achieve the best result, the considered integrated problem was solved with Simulated Annealing meta-heuristic solution approach using R software. Results ⎯ With the proposed new mixed integer nonlinear mathematical model, it has been proved that a small-scale integrated airline scheduling problem of Anadolu Jet airline company can be solved. It has also been reported that the proposed Simulated Annealing meta-heuristic solution approach to achieve the best result can also solve the problem in a short time with R software. Originality / Value ⎯ This study makes a new contribution to the literature on the solution of the integrated problem, proving that the problem of integrated flight, aircraft and crew rescheduling can be solved by proposing a new mixed integer nonlinear programming model that has not been previously considered in the literature.
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    Latest Optimization Approaches for Biogas Supply Chain Management A Literature Survey
    (2021-01-01) S. Erol; Güner, Gürkan Güven
    The efficient use of renewable energy sources is very critical because of the economic reasons. Considering the extreme usage of the fossil fuels around the world, it is also very critical in terms of protecting nature and human health. The use of biogas, which is one of the significant renewable energy sources, is very common in many countries because of its wide usage areas. For example, the recovered biogas can be used for electricity, heating, and transportation fuel. The greenhouse gas (GHG) emission, which causes global climate change, can be reduced significantly by the use of biogas. The optimization of biogas supply chain is necessary to ensure the demand of biogas and biofertilizer by maximum profit and minimum environmental damage. Determining the optimal location of production and purification technologies for the biogas by considering the installation requirements is important to minimize the cost. There are many studies in the literature that try to find alternative solutions by developing different methodological approaches for the optimization of biogas supply chain. In this study, latest studies in the literature are investigated, classified and compared. It is aimed that the implemented literature survey in this study becomes a beneficial guide to develop alternative solution approaches.