TR-Dizin İndeksli Yayınlar Koleksiyonu

Permanent URI for this collectionhttps://acikerisim2.beykoz.edu.tr/handle/20.500.12879/4

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Fault Detection in Pipelines with Graph Convolutional Networks (GCN) Method
(Gazi Üniversitesi, 2024) Şahin, E.; Yüce, H.
Pipeline networks have a wide range of applications, from the transportation of energy sources such as oil and natural gas to the conveyance and distribution of water resources. However, leaks and ruptures in pipelines can cause significant harm to the environment. Therefore, it is crucial to accurately detect pipeline faults in order to avoid economic losses and protect the environment. In this study, pipeline networks carrying water fluid are represented using graph structures. The graph convolutional network (GCN) algorithm is employed for the detection of leaks and blockages in pipeline networks. Experimental methods are employed to collect the necessary data (pressure data) for the GCN algorithm, creating two datasets by considering five different scenarios. The fault detection performance of the GCN algorithm is compared with other graph machine learning algorithms, namely, RGCN, HinSAGE, and GraphSAGE. The results of this study indicate that the performance of the GCN model surpasses that of the other algorithms. Reviewing the literature, accuracy rates for fault diagnosis in pipeline networks using machine learning algorithms range from 78.51% to 99%. In this study, it is found that the GCN, GraphSAGE, HinSAGE, and RGCN algorithms achieve fault detection accuracies of 91%, 90%, 87%, and 89%, respectively, in pipeline networks. Classical machine learning SVM model was used to compare the performance of graph-based algorithms. It is seen that the performances of the algorithms face the literature and the results are above the literature average. © 2024 Gazi Universitesi. All rights reserved.
Lumbar Spine Implant Design with Finite Element Method and Determination of Biomechanical Effects
(Gazi Univ, Fac Engineering Architecture, 2023) Taherzadeh, Paniz; Kelleci, Kubra; Ozer, Sevil
Graphical/Tabular The restoration percentages of two different implants designed and simulated in six different directions are given in Figure A. Figure A. Restoration percentages of theimplant 1 and implant 2 devices in six different directionsPurpose: In this study, it was aimed to design a new pedicle-screw based posterior dynamic stabilization implant that can help stabilize the spine normally. In the study, two different implants were designed using the finite element method (FEM) and their biomechanical effects were compared.Theory and Methods: Stable and treated models of the lumbar spine with two different implants were simulated under physiological loading conditions according to Computed tomography data. Implant and device components were created with the SOLIDWORKS program. All designed devices were used together with ABAQUS CAD simulation program and MATLAB program to calculate range of motion, adjacent level effect and restoration percentages in six different directions (right-left axial rotation, right-left lateral bending and flexion-extension). In the study, 70% restoration percentage, which is an acceptable value in the movement of the spine with the implant, was tried to be achieved in all directions.Results: With the second device, which obtained optimum data and was found to be more flexible, a higher percentage of restoration was obtained in the Z and Y axes. Restoration values are 33% for extension, 53% for flexion, and 68% and 55% for lateral bending and axial rotations, respectively.Conclusion: It can be said that pedicle-screw implants designed with this simulation study will be applicable after experimental validation and clinical trials
Making Sense of Turkey’s Foreign Policy from the Perspective of Neorealism
(Uluslararası İlişkiler Konseyi Derneği, 2023) Oguzlu, Tarik; Han, Ahmet Kasim
This study singles out the impact of systemic and external factors on Turkey's foreign policy from the establishment of the Republic until now. Such an exercise accords with a neorealist interpretation of foreign policy, as the key emphasis is on the impact of the anarchical nature of the external environment, and the influence of the distribution of material power capabilities among states at a given time on foreign policy preferences. This in no way suggests that the internal and individual level of factors holds a secondary place in comparison to systemic/external factors. Yet this article simply highlights the importance of systemic factors, for the main reason that neorealism seems to account for foreign policy choices and behaviors of middle powers more convincingly than in the case of great powers.
Turkey and the Middle East and North Africa Under the AKP: A Three Level Analysis of Foreign Policy Change
(2023) Altunisik, Meliha; Martin, Lenore
This article analyzes the significant foreign policy changes with respect to Turkey’s relations with the Middle East and North Africa region within four relatively distinct periods of the two-decade rule of the Adalet ve Kalkınma Partisi - 2002-2010; 2011-2015; 2016-2020; 2020-2022. It analyzes Turkey’s foreign policy changes based on the application of three intersecting levels of analysis: transformations in the regional and global international system, shifts in domestic politics and changes in individual leadership. The article contributes to the foreign policy literature by demonstrating that the continuity in power of a more centralized government does not guarantee continuity in foreign policy as conceptualized in the literature on foreign policy change.

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