WOS - Web of Science
Permanent URI for this collectionhttps://acikarsiv.thk.edu.tr/handle/123456789/2552
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Publication Biological evaluation, spectroscopic characterization and DFT computations of an oxalamide derivative (BFMO)(2026) Biological evaluation, spectroscopic characterization and DFT computations of an oxalamide derivative (BFMO)Publication A Vibrational Spectroscopic Investigation of 2,2'-Bithiophene Using Experimental and DFT Methods(2023)Organic compounds like 2,2’-Bithiophene (with a synonym. 2,2'-bithienyl, 2,2'-dithienyl)- containing bis(dioxaborin) have drawn significant concern in the area of materials science because of their electron affinity and luminescent properties. With this motivation, we have been concentrating on the properties and functions of 2,2'-Bithiophene.Publication Multi-objective location-distribution optimization in blood supply chain: an application in Turkiye(2024-11-15) Altunoğlu, Burcu; Batur Sir, Gül DidemPurpose Blood donors are crucial in maintaining the blood supply chain. This study aims to improve the location and distribution of blood donation centers by focusing on two main objectives: minimizing costs and maximizing quality. Minimizing costs includes setting up and transporting blood efficiently while maximizing quality to ensure that blood products are delivered to hospitals promptly and in the right quantities. Methods A multi-objective mathematical model is proposed to address the placement of both fixed and mobile blood donation centers. The first objective focuses on minimizing the costs of setting up centers and transporting blood. The second objective aims to maximize quality by ensuring timely deliveries and meeting hospitals’ blood demand. The model utilizes real-world traffic and blood donation data from urban settings to simulate its effectiveness and applicability in practice. The model uses the epsilon constraint method to optimize both objectives simultaneously. Results The model was tested in various scenarios, optimizing cost and quality separately. The algorithm determined the ideal locations for blood donation centers to meet demand by exploring different options. It also accounted for factors that reduce quality, such as delayed deliveries and product returns, and showed that these issues could be minimized. Conclusion This study highlights the need to balance cost and quality when determining the locations of blood donation centers. Using the epsilon constraint method, the model successfully optimized both objectives, offering valuable insights for improving the efficiency and effectiveness of blood donation operations.Publication Implementation of DBSCAN Method in Star Trackers to Improve Image Segmentation in Heavy Noise Conditions(2023) Nevsan ŞENGİL; Şengil, Nevsan; Türk Hava Kurumu Üniversitesi, Uzay Mühendisliği Bölümü, Ankara, TürkiyeStar trackers are currently the most accurate sensors for determining the attitude of a spacecraft. These sensors comprise not only highly capable optical detectors and processor units but also complicated software solvers. One of the main solvers employed in star trackers is image segmentation. In this study, the aim is to develop a hybrid image segmentation method which is a combination of both global thresholding and density-based spatial clustering of applications with noise (DBSCAN) method to increase detection probability of the stars in heavy noise. Secondly, a sorting algorithm is added to list the detected stars in terms of their brightness to increase the efficiency of the star tracking algorithm. Then, this new approach and two different conventional segmentation methods are applied to the Orion star constellation image polluted with Gaussian, salt and pepper, and uneven background noises. The resulting images of these segmentation methods are compared in terms of denoising capabilities. Although computationally more expensive, the proposed DBSCAN-based hybrid method displays a background pixel recovery performance of 99.5%, compared to Otsu global thresholding and adaptive thresholding methods’ 73.5% and 79.9% recovery values, respectively. Additionally, it has been demonstrated that the sorting algorithm successfully listed the detected stars in accordance with their brightness.Publication Empirical Investigation of Small-Scale Aluminium Wool Packed Solar Air Heater Made with Waste Material(Politeknik Dergisi, 2021-12-01) Ataollah Khanları; Azim Doğuş Tuncer; Ceylin Şirin; Faraz Afshari; Afşin GüngörWaste production is an important problem for the developing world and globalization. The waste materials can be reused through recycling process and its environmental effects can be minimized. Utilizing renewable energy sources at the maximum level is also an important issue for a sustainable development in future as well as waste management. In this study, small-scale solar air heating systems were produced from waste materials to analyze the usability of waste material in renewable energy systems. Scrap metal elbows were used in the production of heaters. The first solar heater is hollow (SH) and the second one was modified by filling it with aluminum wool (SHAW). Both heaters were tested simultaneously at different flow rates (0.014, 0.010 and 0.006 kg/s). According to the experimental results, the thermal efficiency values for SH and SHAW were found in the range of 33.63-42.90% and 42.69-56.98%, respectively. In addition, it was observed that a low cost modification such as using aluminum wool can significantly increase thermal performance of the solar heating system.Publication Effect of Cutting Parameters on Surface Roughness and Cutting Forces in Hard Turning of 1.2367 Hot Work Tool Steel(Politeknik Dergisi, 2023-10-01) Sümeyye ERDEM; Mustafa ÖZDEMİR; Mohammad RAFİGHİ; Mehtap YAVUZBu çalışmada 1.2367 sertleştirilmiş (55 HRC) sıcak takım çeliğinin tornalanmasında farklı kesme parametrelerinin yüzey pürüzlülüğü (Ra) ve kesme kuvvetleri üzerindeki etkisi incelenmiştir. Bu deneysel çalışmada, deney tasarımı Taguchi metodu kullanılarak yapılmış ve kesme parametreleri olarak sabit talaş derinliği, üç farklı kesme hızı ve üç farklı ilerleme miktarı seçilmiştir. Kesme parametrelerinin yüzey pürüzlülüğü ve kesme kuvvetleri üzerindeki etkisi varyans analizi (ANOVA) yapılarak değerlendirilmiştir. Sonuçlara göre ilerleme hızındaki artışa bağlı olarak yüzey pürüzlülüğü değerinin arttığı görülmüştür. Kesme hızının ise yüzey pürüzlülük değeri üzerinde belirli bir etkisi görülmemiştir. Radyal kuvvet (Fx), teğetsel kuvvet (Fy) ve ilerleme kuvveti (Fz) üzerinde ise, en etkili parametrenin ilerleme hızı olduğu görülmüştür.