Recep Tayyip Erdoğan Üniversitesi Kurumsal Akademik Arşivi
DSpace@RTEÜ, Recep Tayyip Erdoğan Üniversitesi tarafından doğrudan ve dolaylı olarak yayınlanan; kitap, makale, tez, bildiri, rapor, araştırma verisi gibi tüm akademik kaynakları uluslararası standartlarda dijital ortamda depolar, Üniversitenin akademik performansını izlemeye aracılık eder, kaynakları uzun süreli saklar ve yayınların etkisini artırmak için telif haklarına uygun olarak Açık Erişime sunar.
Güncel Gönderiler
Enhancement of YBCO superconductor magnetic bearing capability by using multiple bulks
(Elsevier, 2025) Savaşkan, Burcu; Güner, Sait Barış; Yılmaz, Ali; Uzun, Oğuzhan; Mollahasanoglu, Hakkı; Öztürk, Ufuk Kemal
Five well-textured single grain YBCO rectangular samples, four of them 13.5 × 13.5 × 7.5 mm3 and one of them 27.4 × 27.4 × 7.5 mm3 in dimensions, were fabricated by top-seeded melt growth (TSMG) method using Nd-123 seeded. These samples were used to investigate the relationship between levitation force and guidance forces between the individual YBCO bulk and their different arrangements and involve permanent magnet (PM) and traditional monopole permanent magnetic guideway (PMG) for the high-Tc superconducting magnetic bearing applications. The levitation and guidance forces of the samples were experimentally measured using a cryogenic load cell setup by a custom-designed three-axis magnetic force measurement system. Additionally, two-dimensional finite element model based on the H-formulation was developed using COMSOL Multiphysics 6.0 to simulate the magnetic interaction between the bulk and the magnet. It was found that the larger sample sizes and multi-bulk arrangements significantly enhanced both levitation and guidance forces compared to a single small bulk. General, the results underscore that, the spatial arrangement and size scaling of HTS bulks play a critical role in maximizing levitation force for superconducting Maglev vehicle and HTS bearing applications. The combined use of experimental and numerical modelling provides a valuable framework for optimizing next-generation HTS systems tailored for high-efficiency, high-stability levitation applications.
Enhancing the performance of conical solar stills through optimised flint stone placement on absorber
(Elsevier, 2026) El Hadi Attia, Mohammed; Elazab M.A.; Cüce, Erdem; Kabeel, Abd Elnaby; Bady, Mahmoud
Water shortage is a significant global issue, necessitating the development of sustainable, energy-efficient desalination technologies. This study aims to determine the optimal spacing of 2 cm diameter flint stones to enhance the efficiency of conical solar stills. Three identical stills were tested over two days: the first had no stones, the second had stones spaced 3 cm apart (61 stones), and the third had stones spaced 4 cm apart (41 stones). On the second day, the first still remained stone-free, while the second and third stills had stones with 5 cm (25 stones) and 6 cm (13 stones) spacing, respectively. The results indicated that the system with 3 cm stone spacing achieved the highest water productivity, yielding 8600 g/m2, significantly surpassing the other configurations: 4 cm (7850 g/m2), 5 cm (7400 g/m2), 6 cm (6900 g/m2), and the baseline system (5600 g/m2). The optimal distance of 3 cm resulted in a 53.57 % improvement over the conventional system. Performance analysis further revealed enhancements across thermodynamic indicators, with the system at 3 cm spacing exhibiting a 56.68 % increase in efficiency, a 190.64 % improvement in exergy efficiency, and a 163.03 % rise in exergy production compared to the baseline. These improvements are attributed to better heat retention and optimized heat transfer dynamics from closer stone placement. The study concludes that using flint stones with a 2 cm diameter and a spacing of 3 cm significantly enhances system performance, offering a scalable and low-cost solution for solar-powered desalination in arid regions.
Unveiling the impact resilience of GFRP and CFRP: A cryogenic exploration through experiment and FE simulation
(Elsevier, 2025) Demiral, Murat; Köklü, Uğur; Yazman, Şakir; Gemi, Lokman; Morkavuk, Sezer
Fiber-reinforced polymer (FRP) composites, particularly carbon fiber-reinforced polymer (CFRP), glass fiber-reinforced polymer (GFRP), and their hybrid configurations, are increasingly employed in aerospace, cryogenic storage, and structural applications due to their superior mechanical properties and tailored performance. However, to date, the studies conducted have not addressed a comparative investigation of the Charpy impact behaviour of CFRP, GFRP and their hybrid configurations under low temperatures. This study investigates the Charpy impact performance of CFRP, GFRP, and CFRP/GFRP hybrid laminates across a wide temperature spectrum ranging from room temperature (RT) to cryogenic conditions (RT, −50 °C, −100 °C, −150 °C, and −196 °C). Samples were fabricated via vacuum bagging with unidirectional fibers and epoxy resin and tested at both 0° and 90° fiber orientations to examine anisotropic behavior. To complement the experimental results, a three-dimensional finite element model was developed to simulate the temperature-dependent impact response. In the numerical framework, intraply damage was modeled using a continuum damage mechanics approach based on Hashin's failure criteria, capturing fiber and matrix degradation. Interlaminar damage evolution was represented through cohesive zone elements embedded between plies to simulate delamination under impact loading. The findings reveal that temperature markedly influences energy absorption, damage morphology, and failure modes, with hybrid laminates exhibiting improved impact tolerance and balanced mechanical behavior. This integrated experimental–numerical investigation provides critical insights into the cryogenic impact performance of FRP composites, supporting the development of robust materials for demanding low-temperature environments.
Turbulent thermal-magneto convection in a teardrop-shaped dimpled tube: An experimental and numerical study
(Elsevier, 2026) Dağdeviren, Abdullah; Gürsoy, Emrehan; Gürdal, Mehmet; Gedik, Engin; Arslan, Kamil
In this study, the forced convection properties of teardrop-shaped dimpled fins, Fe 3 O 4 /H 2 O ferrofluid, and constant magnetic field parameters were investigated numerically and experimentally. The study consists of two parts. In the first part, a numerical simulation was conducted, incorporating all relevant parameters, and the results were analyzed. In the second part, the experimental setup was completed for the scenario that yields the highest performance evaluation criterion value, as determined from the numerical results. The Reynolds number (10000≤ Re ≤ 50000), the size of the teardrop-shaped dimple ( BTD , MTD and STD ), dimples distance (30≤ P ≤ 50), constant heat flux ( qʺ = 20 kW/m2), ferrofluid concentration ratio (0.0≤ φ vol. ≤2.0) and the constant magnetic field strength applied at x/D = 20 location (0 T ≤ B 0 ≤ 0.3 T) were studied experimentally and numerically. The findings showed that the DT9 case increased the thermal performance change by 36.18 % compared to the smooth tube. The highest heat transfer rate occurred in the magnetic field strength B 0 = 0.3 T. The magnetic field strength caused an improvement in heat transfer of 5.12 % and 7.32 % in the Nusselt number, respectively, in the numerical and experimental results. The highest PEC was obtained by using φ vol. = 2.0 % Fe3O4/H2O nanofluid in case DT9 ( STD , P = 50 mm) at Re = 10000 and B 0 = 0.3 T, with a contribution of 32.45 % compared to the smooth tube. The compound effect amounts of teardrop-shaped dimples, ferrofluid, and constant magnetic field were obtained numerically and experimentally as 55.41 % and 55.37 % in Nusselt number, while obtained as 29.15 % and 32.45 % in PEC , respectively, compared to a smooth tube, using H2O and the absence of a constant magnetic field.
Recent advances in shikonin nanoformulations for managing inflammation-related disease
(TMR Publishing Group, 2026) Zuo, Ting-Ting; Zhang, Jun-Jie; Altuntaş, Derya Bal; Yang, Dong-Liang; Zhang, Chao
Shikonin, a naphthoquinone compound derived from the root of Lithospermum erythrorhizon, has been extensively studied for its antibacterial, antioxidant, and anti-inflammatory properties. Increasing evidence highlights its potential in treating inflammation-related diseases. However, its clinical application is hindered by challenges such as poor water solubility, rapid metabolism in vivo, and other limitations. Recent advancements have demonstrated that encapsulating shikonin within nanocarriers can significantly enhance its water solubility and pharmacokinetic profile. Building on this, this perspective paper outlines the current landscape of inflammation treatment, explores the anti-inflammatory mechanisms of shikonin, reviews the latest progress in shikonin-based nanomaterials for anti-inflammatory applications, and discusses the challenges and future directions for the clinical translation of shikonin nanoformulations.
