TR Dizin İndeksli Yayınlar Koleksiyonu / TR Dizin Indexed Publications Collections

Permanent URI for this collectionhttps://hdl.handle.net/20.500.13091/4

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Citation - WoS: 1
Determination by Numerical Modeling of Stress-Strain Variations Resulting From Gallery Cross-Section Changes in a Longwall Top Coal Caving Panel
(2024) Mesutoğlu, Mehmet; Özkan, İhsan; Rodrıguez Dono, Alfonso
As a major pillar of global energy production, coal mining requires continuous advancements in efficiency to contribute to the broader goal of energy sustainability, all the while the shift towards more sustainable energy sources is underway. Mechanized excavation systems employed in underground coal mines, particularly within the longwall mining method, enable high-tonnage coal production. The Longwall Top Coal Caving (LTCC) method, one of the longwall mining techniques, has been developed for the effective extraction of coal from thick coal seams. However, as mining operations delve deeper, various complex issues, such as gallery cross-sectional variation, emerge. Gallery cross-sectional variation can increase the risk of collapse by affecting the stress distribution in the rock mass, posing a threat to worker safety. This study centers on the numerical modeling and analysis of gallery cross-sectional variation in the Ömerler underground mine, operated by the Turkish Coal Enterprises (TKI), West Lignite Enterprise (GLI). To achieve this objective, an extensive database was established through field and laboratory rock mechanics studies. This database was then utilized in the Fast Lagrangian Analysis of Continua 3D (FLAC3D) (v6.0) program to simulate the cross-sectional variations of the A6 panel in the Ömerler underground mine. The numerical simulation results provide valuable insights into the secondary stress-deformation changes associated with gallery cross-sectional variation.
Energy, Environmental, and Exergoeconomic (3e) Analysis of Transcritical Co2 Booster and Parallel Compression Supermarket Refrigeration Cycles in Climate Zones of Türkiye
(2024) Çürkyılmaz, Oğuz; Ersoy, H. Kürşad
Legal restrictions on high-GWP refrigerants lead to the widespread use of carbon dioxide in commercial refrigeration, where there is a high energy consumption. Although CO2 has many benefits, its lower critical temperature and higher operation pressure compared to other refrigerants lead to performance reduction. For this reason, studies have been conducted by researchers for performance enhancement. This paper presents energy, environmental impact, and exergoeconomic (3E) analysis of transcritical CO2 booster and parallel compression supermarket refrigeration cycles based on meteorological data of 11 provinces in Türkiye as samples of different climatic regions. Parallel compression cycle achieved up to 18.4% higher coefficient of performance than booster cycle between the investigated ambient temperatures. Up to 5.6% annual energy consumption and environmental impact reduction were obtained using parallel compression. Unit product costs of the parallel compression cycles were calculated between 8.2% and 18% lower than booster cycle in investigated provinces. Developing energy-efficient systems that use environmentally friendly refrigerants will contribute to a sustainable future.
Failure Analysis of a Base Support Plate of a Semolina Purifier Machines Subjected To Fatigue Loading
(2024) Korkmaz, Hasan Hüsnü; Dere, Yunus; Ekem, Hakkı; Şahin, Ömer Sinan
The semolina purifier is a machine used in the production phase in flour factories and is exposed to fatigue loads. In this study, the reason for the damage when a semolina purifier machine breaks during use and the improvements that need to be made in the design are discussed. For this purpose, a finite element model (FEM) was created using ABAQUS software. As a result of the analysis, it was determined that the design of the machine support platform should be improved. A two-stage strengthening alternative is designed. The cyclic loads applied by the twin motors that move the machine screens are applied in the FEM model. The deformations and stresses occurring in the reinforced and existing design machine base plate were compared. The results showed that, the maximum equivalent stress level can be reduced from 86 MPa to 35 MPa by design improvements made on the base plate.
Citation - WoS: 1
Gis-Ahp Approach for a Comprehensive Framework To Determine the Suitable Regions for Geothermal Power Plants in İzmir, Türkiye
(2024) Koca, Kemal; Karipoğlu, Fatih; Öztürk, Emel Zeray
Geothermal energy is gaining more reputation and importance around the world. Correspondingly, suitable location selection is a critical step and has become necessary for the successful installation and operation of geothermal power plants. This study investigated suitability of İzmir region, located in the Aegean part of Türkiye, in terms of geothermal power plants applications by using the combination of Geographical Information System and Analytic Hierarchy Process. Based on the request of power plants, thirteen important criteria were evaluated under three main categories named as physical (C1), environmental (C2) and technical (C3). Moreover, expert’s opinions were taken into consideration to calculate the importance of these criteria. Key results showed that İzmir was suitable for geothermal power plants. The final suitability map layer pointed out that %8.73 (1.037 km2) of total area were determined as highly suitable regions in terms of installation. In addition, the obtained suitability map layer was compared with actual geothermal power plants. Based on the comparison study, power plants in Seferihisar were moderately suitable for geothermal power plants while the location of Balçova power plant was highly suitable. Regarding the suitability assessment in the present study, the location of Dikili power plants had the least suitability score.
An Integrated Framework for Assessment of Urban Forms and Their Transformation
(2023) Türkyılmaz, Muzaffer; Topçu, Mehmet
This paper addresses an integrated framework on the basis of different urban morphological theories: histocico-geographical approach, space syntax, and the Morpho method. It includes eleven criteria focusing on the assessment of urban forms and their transformations. These criteria are the accessibility of streets, connectivity of streets, intelligibility, synergy, street block size, plot size, building coverage, floor area ratio, block-plan size based on the town-plan or ground plan; building height and total constructed area (density of buildings) based on building fabric. Sekiz Mahalle (Konya, Turkey) is used to validate the methodological procedures of this integrated framework. The implementation of the methodology enables a strong basis for how an urban area should be transformed, and what should be followed before any interventions in the urban landscape. It is argued that this methodology can provide a smoother transition of the physical form of cities. It can play a substantial role in the preparation of municipal plans and designs in which any change is needed, balancing the conservation and transformation of morphological constituents of the urban landscape.
Production of Cuo/Zro2 Nanocomposites in Powder and Fiber Forms
(2024) Çürkyılmaz, Zeynep
CuO/ZrO2 composite systems were synthesized in two different ways and comprehensively characterized with X-ray diffraction(XRD), Fourier transform infrared spectroscopy(FTIR), scanning electron microscopy(SEM), transmission electron microscopy(TEM), and energy dispersive X-ray spectroscopy(EDX). These metal oxide samples were prepared by hydrothermal synthesis and electrospinning process. In these methods, the same metal salts were used as precursors. Separately produced ZrO2 nanoparticles(NPs) and CuO particles have spherical and cube-like shapes, and both morphologies have monoclinic structures. However, ZrO2 and CuO particles do not have uniform diameters, and the average size of these particles ranges between 6–17 and 215–847 nm, respectively. Moreover, CuO/ZrO2 nanocomposite particles(NCPs) were synthesized using a facile and one-pot hydrothermal technique. They have uniform, spherical, and monoclinic structures with a 15nm average diameter. Furthermore, ZrO2 fibers were produced with the electrospinning process as highly crystalline structures after annealing, with a 230 nm average fiber diameter. In addition, ZrO2 fibers were doped with hydrothermally synthesized CuO particles with a drop-casting method for the first time. This study clearly shows that particle-fiber structure allows the development of the efficiency of p-type counterparts by using only 0.5-1.5wt.% n-type. With these results, two methods can be used to produce heterostructure CuO/ZrO2 composite particles/fibers and as potential for photocatalytic degradation.

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