Browsing by Author "Coskun, Safa Bozkurt"

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Citation - WoS: 2
Citation - Scopus: 2
Analysis of the Motion of a Rigid Rod on a Circular Surface Using Interpolated Variational Iteration Method
(Yildiz Technical Univ, 2022) Coskun, Safa Bozkurt; Senturk, Erman; Atay, Mehmet Tarik
In this paper, interpolated variational iteration method (IVIM) is applied to investigate the vibration period and steady-state response for the motion of rigid rod rocking back and forth on a circular surface without slipping. The problem can be considered as a strongly nonlinear oscillator. In this solution procedure, analytical variational iteration technique is utilized by evaluating the integrals numerically. The approximate analytical results produced by the presented method are compared with the other existing solutions available in the literature. The advantage of using numerical evaluation of integrals, the method becomes fast convergent and a highly accurate solution can be obtained within seconds. The authors believe that the presented technique has potentially wide application in the other nonlinear oscillation problems.
Citation - WoS: 2
Citation - Scopus: 2
Interpolated Variational Iteration Method for Solving the Jamming Transition Problem
(Elsevier, 2019) Coskun, Safa Bozkurt; Atay, Mehmet Tarik; Senturk, Erman
The purpose of this study is to present an analytical based numerical solution for Jamming Transition Problem (JTP) using Interpolated Variational Iteration Method (IVIM). The method eliminates the difficulties on analytical integration of expressions in analytical variational iteration technique and provides numerical results with analytical accuracy. JTP may be transformed into a nonlinear non-conservative oscillator by Lorenz system in which jamming transition is presented as spontaneous deviations of headway and velocity caused by the acceleration/breaking rate to be higher than the critical value. The resulting governing equation of JTP has no exact solution due to existing nonlinearities in the equation. The problem was previously attempted to be solved semi-analytically via analytical approximation methods including analytical variational iteration technique. The results of this study show that IVIM solutions agree very well with the numerical solution provided by the mathematical software. IVIM with two different formulation according to governing equation is introduced. Required order of the solution and number of time steps for a good agreement is determined according to the analyses performed using IVIM. (C) 2019 International Association for Mathematics and Computers in Simulation (IMACS). Published by Elsevier B.V. All rights reserved.
Resilience and Market Diversification in Sustainable Tourism: Evidence from International Arrivals to Türkiye (2012-2025)
(Emerald Group Publishing Ltd, 2026) Atay, Mehmet Tarik; Ciuffreda, Raffaela; Coskun, Safa Bozkurt
PurposeThis study analyzes the possible connections between resilience and market diversification of inbound tourism to T & uuml;rkiye from 2012 to 2025. The aim is to assess the reaction of international arrivals to global fluctuations, such as the COVID-19 pandemic era, and to examine the structural linkage to primary source markets within the concept of sustainable tourism management.Design/methodology/approachThe research uses annual country-specific data related to international arrivals. We used time-series analysis to uncover long-term behaviors and the consequences of crises. The research also used Shannon entropy and the Herfindahl-Hirschman Index to look at market concentration and diversity. A comparative analysis of the primary source countries indicates variations in recovery trajectories and resilience in the concept of sustainable tourism management.FindingsThe results show that T & uuml;rkiye's inbound tourism grew steadily until 2019, decreased severely during the pandemic and then bounced back strongly from 2022 to 2024. Market diversity has improved over time, but dependence on Germany and the Russian Federation tourists' activities is still high. Although the UK was more stable, and regional markets like Bulgaria and Iran were more unstable, their positive effect on achieving the sustainable tourism goal is still weak.Research limitations/implicationsThe study is constrained by the partial coverage of 2025 data and the lack of direct indicators for environmental or social sustainability. Future research may combine these dimensions and their data to construct a more thorough and detailed evaluation for better understanding of the sustainable tourism context.Practical implicationsThe results show that for tourism in T & uuml;rkiye to be sustainable, it needs to have more diverse source markets, be better prepared for global or local crises and have plans for managing capacity, especially tourism management and seasonality. These insights can help government policymakers and local destination management bodies make long-term sustainability stronger.Social implicationsHighly concentrated tourism markets may cause revenue and employment volatility when principal source countries experience a downturn. Advocating for diversity in terms of various source markets for inbound tourism activities enhances tourism-related economic and social resilience and community welfare in terms of stable income flow and fosters inclusive growth throughout the local and national community in accordance with sustainable tourism objectives.Originality/valueThis study directly connects resilience and diversity to the management of sustainable tourism in a new destination. By integrating long-term real case data with related, respected and detailed market structure metrics, it offers novel insights into how destinations might improve their competitiveness, decreased vulnerabilities in crisis time periods and improve the sustainability of the tourism sector.
Citation - WoS: 5
Citation - Scopus: 6
Solution of Jamming Transition Problem Using Adomian Decomposition Method
(Emerald Group Publishing Ltd, 2018) Senturk, Erman; Coskun, Safa Bozkurt; Atay, Mehmet Tarik
Purpose The purpose of the study is to obtain an analytical approximate solution for jamming transition problem (JTP) using Adomian decomposition method (ADM). Design/methodology/approach In this study, the jamming transition is presented as a result of spontaneous deviations of headway and velocity that is caused by the acceleration/breaking rate to be higher than the critical value. Dissipative dynamics of traffic flow can be represented within the framework of the Lorenz scheme based on the car-following model in the one-lane highway. Through this paper, an analytical approximation for the solution is calculated via ADM that leads to a solution for headway deviation as a function of time. Findings A highly nonlinear differential equation having no exact solution due to JTP is considered and headway deviation is obtained implementing a number of different initial conditions. The results are discussed and compared with the available data in the literature and numerical solutions obtained from a built-in numerical function of the mathematical software used in the study. The advantage of using ADM for the problem is presented in the study and discussed on the basis of the results produced by the applied method. Originality/value This is the first study to apply ADM to JTP.
Twist-Bend Instability of a Cantilever Beam Subjected to an End Load via Homotopy Perturbation Method
(Amer Inst Physics, 2018) Yucesoy, Ahmet; Coskun, Safa Bozkurt; Atay, Mehmet Tarik
In this article, twist-bend buckling analysis of a cantilever beam subjected to a concentrated end load is conducted using Homotopy Perturbation Method (HPM). Even in the linear stability analysis, obtaining an exact solution for some cases is not an easy task. However, by the use of HPM this difficulty can be overcome easily. This issue is presented with a case study and the results show that HPM can be used successfully in the analysis of twist-bend buckling of beams.