Atılım Academic Archive (Atılım University)
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The Design and Techno-Economic Evaluation of Wind Energy Integrated On-Site Hydrogen Fueling Stations for Different Electrolyzer Technologies
No full textHydrogen refueling stations (HRS) integrated with renewable energy sources present a pivotal solution for achieving sustainable transportation systems. This study focuses on the design and techno-economic analysis of a grid-connected, on-site hydrogen production HRS powered by wind energy, incorporating various electrolyzer technologies. The selected location for the HRS installation is & Ccedil;anakkale, Turkey, where daily wind speed data has been utilized for performance calculations. The proposed HRS system integrates a wind turbine (WT) with three different electrolyzer technologies: alkaline electrolyzer (AEL), proton exchange membrane electrolyzer (PEMEL), and anion exchange membrane electrolyzer (AEMEL). A comprehensive techno-economic analysis was conducted to evaluate the system's performance, considering factors such as initial capital investment, installation, operation, and replacement costs. The results of the analysis reveal that the levelized cost of hydrogen (LCOH) varies between 9.0 and 18.7 /kg H2, depending on the type of electrolyzer technology used and the daily hydrogen refueling capacity. Notably, increasing the hydrogen refueling capacity significantly reduces production costs. The minimum LCOH of 9.0 /kg H2, achieved under a 20-year investment scenario, corresponds to a refueling capacity of 250 kg H2/day when utilizing the AEL-integrated HRS system. The findings underscore the economic feasibility of on-site hydrogen refueling stations powered by wind energy and utilizing AEL, AEMEL, and PEMEL systems. Among the systems analyzed, the AEL-based HRS system demonstrated the highest return on investment (ROI) of 13.02 % and the shortest payback period (PBP) of 7.7 years, highlighting its economic performance. This study provides valuable insights into the integration of renewable energy with hydrogen production infrastructure, emphasizing the potential of wind-powered HRS systems to advance the sustainability and economic viability of hydrogen-based transportation solutions.Science Citation Index Expande
Enhancing Urban Sustainability With Novel Vertical-Axis Wind Turbines: a Study on Residential Buildings in Çeşme
No full textThis study investigates the integration of three types of vertical-axis wind turbines (VAWTs)-helical, IceWind, and a combined design-on residential buildings in & Ccedil;e & scedil;me, T & uuml;rkiye, a region with an average wind speed of 7 m/s. The research explores the potential of small-scale wind turbines in urban areas, providing sustainable solutions for renewable energy generation and reducing reliance on conventional energy sources. The turbines were designed and analyzed using SolidWorks and ANSYS Fluent, achieving power outputs of 350 W for the helical turbine, 430 W for the IceWind turbine, and 590 W for the combined turbine. A total of 42 turbines were mounted on a five-storey residential building model, and DesignBuilder software was utilized to simulate and evaluate the energy consumption. The baseline energy consumption of 172 kWh/m2 annually was reduced by 18.45%, 22.93%, and 30.88% for the helical, IceWind, and combined turbines, respectively. Furthermore, the economic analysis showed payback periods of 12.89 years for the helical turbine, 10.60 years for the IceWind turbine, and 10.49 years for the combined turbine. These findings emphasize the viability of integrating VAWTs into urban buildings as an effective strategy for reducing energy consumption, lowering costs, and enhancing energy efficiency.Enermet Energy Meteorology Engineering Inc.The APC was funded by Enermet Energy Meteorology Engineering Inc.Science Citation Index Expanded - Social Science Citation Inde
Association of Ghrelin, Nesfatin-1, and Vaspin with Diabetes Mellitus
No full textBu tez çalışmasında, Diabetes Mellitus'lu bireylerde spesifik adipokinler olan Ghrelin, Nesfatin-1 ve Vaspin düzeyleri incelenmiş ve bu düzeylerin glisemik kontrol göstergelerinden biri olan HbA1c ile olası ilişkileri değerlendirilmiştir. Diabetes Mellitus, küresel yaygınlığı giderek artan, insülin direnci, glukoz metabolizmasında bozulma ve kronik inflamasyon ile karakterize karmaşık bir metabolik hastalıktır. Adipoz dokudan salgılanan adipokinlerin insülin duyarlılığı, enerji dengesi ve inflamatuar yanıtların düzenlenmesinde önemli roller oynadığı bilinmektedir. Bu moleküllerin diyabet patofizyolojisindeki etkileriyle ilgili yapılan önceki çalışmalar, tanısal biyobelirteç veya terapötik hedef olarak potansiyel taşıdıklarını öne sürmektedir; ancak bu ilişkilerin mekanizmaları hâlâ netlik kazanmamıştır. Bu araştırmada, ELISA yöntemi ile kan örneklerinde yapılan biyokimyasal analizler ve HbA1c düzeyleriyle yapılan istatistiksel korelasyon çalışmaları sonucunda, adı geçen adipokinlerin diyabet tanı ve tedavisindeki potansiyel önemine dair veriler elde edilmiştir. Bulguların, diyabetin patofizyolojisine dair daha derin bir anlayış geliştirilmesine ve gelecekteki tanı/tedavi stratejilerine bilimsel katkı sunması beklenmektedir.This thesis aims to investigate the levels of specific adipokines—Ghrelin, Nesfatin-1, and Vaspin—in individuals with Diabetes Mellitus and examine their associations with glycemic control markers such as HbA1c. Diabetes Mellitus is a complex metabolic disorder with increasing global prevalence and is associated with insulin resistance, impaired glucose metabolism, and chronic inflammation. Adipokines secreted from adipose tissue are known to play regulatory roles in insulin sensitivity, energy homeostasis, and inflammatory responses. While previous studies have suggested that these molecules may serve as potential biomarkers or therapeutic targets in diabetes, their specific mechanisms and relationships with metabolic indicators remain unclear. Through biochemical analysis of blood samples using ELISA and statistical correlation with HbA1c levels, this study provides insights into the potential diagnostic and therapeutic significance of these adipokines in diabetes. The findings are expected to contribute to a deeper understanding of the pathophysiology of diabetes and offer scientific support for future strategies in diagnosis and treatment
Role of Latissimus Dorsi-Thoracolumbar Fascia Complex Stretching on Pain and Pain-Related Parameters in Patients With Chronic Low Back Pain: A Randomised Clinical Trial
No full textBackground Fascial stretching is gaining interest as a potential intervention for pain management. However, evidence regarding the effect of latissimus dorsi-thoracolumbar fascia (LD-TLF) complex stretching in patients with chronic low back pain (CLBP) remains limited. Therefore, this study aimed to investigate the effects of LD-TLF complex stretching on pain-related factors and disability in patients with CLBP. Methods Thirty patients with CLBP were randomly assigned to a study group (n = 15; 7 men, 8 women) and a control group (n = 15; 7 men, 8 women). The study group received 4 weeks of LD-TLF complex stretching in combination with conventional physiotherapy, while the control group received conventional physiotherapy only. Outcomes were assessed before and after the interventions, including primary measures of pain pressure thresholds (PPT) at thoracolumbar fascia levels (L1, L3 and 12th costa), and secondary measures included the Pain Sensitivity Questionnaire (PSQ), the effects of pain on daily activities measured by the Brief Pain Inventory (BPI), and disability assessed by the Oswestry Disability Questionnaire (ODQ). Results Pre- and post-treatment PPTs, at the L1, L3 vertebrae and 12th costa levels, demonstrated significant differences between the study group and control groups. Post-treatment thresholds were significantly higher compared to pre-treatment thresholds (p < 0.001, eta p(2) = 0.67; p < 0.001, eta p(2) = 0.61; p < 0.001, eta p(2) = 0.74). Additionally, significant improvements were found in PSC, BPI and ODQ scores in the study group compared to the control group (p < 0.05). Conclusion The results of this study suggest that stretching the LD-TLF complex may be a beneficial addition to the conventional physiotherapy approach for patients with CLBP. Specifically, LD-TLF complex stretching, when used in combination with conventional physiotherapy, appears to provide improved pain thresholds, decreased pain sensitivity and pain during activity, as well as reduced disability compared to conventional physiotherapy alone in patients with CLBP
Bacterial Profiling of Brined Grapevine Leaves Collected From Different Local Markets in Türkiye
No full textMicroorganisms linked to the grapevine, Vitis vinifera, can impact crop quality, plant growth, and human and plant health. This study examined the bacterial community structures of brined grapevine leaves (n = 56) taken from seven distinct regions in Türkiye using next-generation sequencing technology. Investigations were also conducted into the samples' chemical properties. Firmicutes was the dominant phylum, followed by Proteobacteria, Actinobacteria, and Bacteroidetes. Bacillaceae was the predominant family in the analyzed samples, followed by Clostridiaceae, Peptostreptococcaceae, and Enterobacteriaceae. Bacillus was the dominant genus, followed by Lysinibacillus and Clostridium sensu stricto. The samples exhibited differences in terms of pH, total acidity, and salt content. The pH values of the brined grapevine leaves ranged from 2.31 to 6.91, the acidity levels ranged from 0.09% to 1.80%, and the salt percentages ranged from 3.39% to 49.14%. This research provides pioneering information for bacterial community analysis of brined grapevine leaves. © 2025 Wiley-VHCA AG, Zurich, Switzerland.Science Citation Index Expande
Early Posterior Corneal Changes and Belin/Ambrosio Scores Following Photorefractive Keratectomy: a Pentacam Study
No full textYakar, Konuralp/0000-0002-3839-5699; Alacamli, Goksu/0000-0001-5013-9981;Introduction: To evaluate early postoperative changes in the posterior corneal surface, anterior chamber parameters, and Belin/Ambrosio Enhanced Ectasia Display (BAD) scores following photorefractive keratectomy (PRK) using Pentacam tomography. Methods: This observational study included 102 eyes of 51 patients (mean age 28.43 +/- 6.27 years) undergoing alcohol-assisted PRK for myopia and/or astigmatism. Preoperative and 1-month postoperative assessments were performed using the Pentacam system, measuring, anterior chamber depth (ACD), anterior chamber volume (ACV), central corneal thickness, posterior keratometry, posterior elevation, and BAD scores. PRK was conducted with a WaveLight (R) EX 500 excimer laser, followed by mitomycin-C application. Statistical analysis utilized paired t-tests and Pearson's correlation. Results: At 1 month post-PRK, ACV significantly decreased (p < 0.01), while ACD reduction was not significant (p = 0.40). Posterior keratometry (K1, K2, Kmean) and astigmatism decreased (p < 0.01), with a mean posterior elevation increase of -2.50 +/- 2.94 mu m (p < 0.01). A weak negative correlation was observed between maximum posterior elevation difference and ablation depth (p = 0.03, r = -0.20) and ablation depth/preoperative pachymetry ratio (p = 0.03, r = -0.20). BAD-D scores (Dp, Dt, Da, total D) significantly increased (p < 0.01), except for Df (p = 0.41). No correlation was found with preoperative pachymetry or residual stroma. Conclusions: PRK induces minimal posterior corneal protrusion and BAD score changes at 1 month, potentially mimicking early ectasia. Multimodal testing is advised for accurate ectasia detection. Larger, longer-term studies are needed to validate these findings.Science Citation Index Expande
Complex Partial Differential Equations
No full textThe Schwarz and iterated Dirichlet boundary-value problems are reported on for the polyanalytic operator in certain plane domains having a harmonic Green function. Hybrid polyharmonic Green functions are reviewed upon which open a variety of boundary-value problems for the polyharmonic operator. This topic is far from being complete. The higher the order of the polyharmonic operator the richer is the theory of related hybrid Green functions: they are constructed by continued convoluting harmonic Green, Neumann, Robin functions also incorporating polyharmonic Green–Almansi functions. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2025
Applying Asymmetric Theory to Optimise Instructional, Assessment, and Administrative Designs of Intensive English Programmes
No full textAsymmetric Theory emphasizes optimisation, efficiency, and economy by harnessing the transformative power of asymmetry. It offers practical and functional solutions to some complex daily and scientific problems through the application of multilayered asymmetric thinking. The process begins with the careful identification of the most dominant factors influencing the success of the solutions to the problems, ultimately leading to the creation of a main key to successand sub keys to success attached to it. The key tosuccess serves as a guide for its creator as it highlights which factors should be controlled and which should be prioritised over the others. As a result, Asymmetric Theory introduces a structured strategy-oriented approach to problem-solving. This chapter begins by highlighting the importance of Intensive English Programmes (IEPs) for English-medium universities. Then, it introduces the core principles of Asymmetric Theory. Building on these principles, a main key to success is created for the programme development challenge of IEPs followed by the creation of sub keys for optimising their instructional, assessment, and administrative designs. These steps are demonstrated using a think-aloud protocol. Ultimately, this chapter presents how the instructional, assessment, and administrative designs of an educational programme can be effectively optimised through the lens of Asymmetric Theory using IEPs as a comprehensive example. © 2025 The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG
ISAR Imaging of Drone Swarms at 77 GHz
No full textThe proliferation of easily available, internet-purchased drones, coupled with the emergence of coordinated drone swarms, poses a significant security threat for airspace. Detecting these swarms is crucial to prevent potential accidents, criminal misuse, and airspace disruptions. This paper proposes a novel inverse synthetic aperture radar (ISAR) imaging technique for high-resolution reconstruction of drone swarms at 77 GHz millimeter wave (mmWave) frequency, offering a valuable tool for military and defense antidrone systems. The key parameters affecting down-range and cross-range resolution (0.05 m), ultimately enabling the generation of detailed ISAR images are discussed. Here, we create diverse scenarios encompassing various swarm formations, sizes, and payload configurations by employing ANSYS simulations. To enhance image quality, different window functions are evaluated, and the Hamming window is selected due to its highest peak signal-to-noise ratio (PSNR) (16.3645) and structural similarity (SSIM) (0.9067) values, ensuring superior noise reduction and structural preservation. The results demonstrate that the effectiveness of high-resolution ISAR imaging in accurately detecting and characterizing drone swarms pave the way for enhanced airspace security measures
Some Fixed Point Results on Interpolative Metric Spaces
No full textThis paper aims to introduce some basic fixed point theorems on interpolative metric space that is a natural extension of standard metric space.Science Citation Index Expande