Atılım Academic Archive (Atılım University)
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Design and Techno-Economic Analysis of Solar Energy Based On-Site Hydrogen Refueling Station
No full textDEVRIM, YILSER/0000-0001-8430-0702This paper presents a detailed techno-economic review and assessment of a hydrogen refueling station (HRS) powered by a grid-connected photovoltaic (PV) system to address the issues of carbon emissions and energy sustainability in transportation. In the study, the HRS system with 1, 3 and 5 MW PV installed capacity for Ankara, the capital city of T & uuml;rkiye, is considered for different system lifetimes. In the proposed HRS, on-site hydrogen production is achieved through anion exchange membrane water electrolysis (AEMWE) using a grid-connected PV system, and the produced hydrogen is stored in a cascaded storage system and is utilized at the HRS station. In order to evaluate the cost competitiveness and economic viability of the designed HRS system, the levelized cost of hydrogen (LCOH) is determined by considering the initial investment costs, operating expenses and potential revenue streams. The results show that the HRS capacity, PV installed capacity and system lifetime significantly impact the LCOH. The technoeconomic analysis results show that the best system configuration was determined as 8.54 /kg H2 in the 20-year long term refueling scenario for a 5 MW installed PV capacity with a daily refueling capacity of 170 kg H2. This study contributes to the development of sustainable energy infrastructure by providing a comprehensive framework for the design, calculation and economic evaluation of PV-integrated hydrogen refueling stations. The results provide valuable information for policymakers, industry stakeholders, and researchers to help achieve a carbon-neutral transportation sector and promote energy sustainability.Science Citation Index Expande
Characterization of Linear and Nonlinear Optical Properties of Nabi(wo4)2 Crystal by Spectroscopic Ellipsometry
No full textgasanly, nizami/0000-0002-3199-6686; Isik, Mehmet/0000-0003-2119-8266NaBi(WO4)2 compound has been a material of considerable attention in optoelectronic applications. The present research, in which we examined the linear and nonlinear optical properties of NaBi(WO4)2 crystal using the spectroscopic ellipsometry method, elucidates the optical behavior of the crystal in detail. Our work provides a sensitive approach to determine the spectral characteristic of the crystal. The spectral dependence of various optical parameters such as refractive index, extinction coefficient, dielectric function and absorption coefficient was reported in the range of 1.2-5.0 eV. Optical values such as bandgap energy, critical point energy, single oscillator parameters were obtained as a result of the analyses. In addition to linear optical properties, we also investigated the nonlinear optical behavior of NaBi(WO4)2 and shed new light on the potential applications of the crystal. Absorbance and photoluminescence spectra of the crystal were also reported to characterize optical, electronic and emission behavior of the compound. Our findings may form the basis for a number of technological applications such as optoelectronic devices, frequency conversion, and optical sensors. This research contributes to a better understanding of the optical properties of NaBi(WO4)2 crystal, highlighting the material's role in future optical and electronic technologies
Sar Imaging for Non-Destructive Testing With Commercial Radar Platforms
No full textTicari olarak temin edilebilen frekans modülasyonlu sürekli dalga (FMSD) milimetre dalga (mmDalga) radarları, mmDalga teknolojisindeki son gelişmelerle beraber radar görüntüleme uygulamalarında giderek daha popüler hale gelmiştir. mmDalga sensörlerinin derin penetrasyon ve yüksek çözünürlük yetenekleri sayesinde, mmDalga sensörlerini benimseyen sentetik açıklıklı radar (SAR) görüntüleme uygulamaları, tahribatsız muayenede (TM) kusur tespiti için büyük bir vaat taşımaktadır. Bununla birlikte, yüksek çözünürlüklü görüntüleme elde etmek için önerilen algoritmik, yapısal ve deneysel çözümler genellikle yüksek maliyet ve karmaşıklık sorunlarıyla sonuçlanmaktadır. Dahası, verimli işleme açısından optimize edilmiş sistem parametreleriyle düşük yansıtıcı malzemelerdeki asgari kusurları tespit etmek ve kusurlu nesnelerin otomatik tespiti yeterince ele alınmamaktadır. Bu tez, SAR görüntülerinden derin öğrenmeye dayalı otomatik kusur tespiti uygulamasını ve TM uygulamalarında kullanım için özel olarak optimize edilmiş sistem parametrelerine sahip yüksek çözünürlüklü ve uygun maliyetli iki boyutlu (2B) mmDalga SAR görüntüleme sistemini tanıtmaktadır. 77 ile 81 GHz arasında çalışan ticari olarak satılan (TOS) bir FMSD radar sensörüyle entegre edilmiş iki eksenli otonom bir tarayıcı inşa etmekteyiz. Deneysel ölçümler, radar sensörünün tek bir alıcı-verici çiftini kullanan bir laboratuvar ortamında gerçekleştirilmektedir. FMSD radar sinyal özellikleri, mekansal örnekleme aralıkları ve tarama açıklıkları dahil olmak üzere yeniden oluşturulan görüntü kalitesini etkileyen sistem parametreleri, yüksek çözünürlük ve düşük hesaplama karmaşıklığı elde etmek için optimize edilmiştir. Düşük yansıtıcı ve hasarlı olanlar dahil olmak üzere farklı tür ve boyutlardaki nesnelerin SAR görüntüleri elde edilmiş ve sistem parametrelerinin görüntü kalitesi üzerindeki etkisi araştırılmıştır. Hedef malzemenin bileşiminin SAR görüntüleme üzerindeki etkisiyle birlikte, hedefte görsel olarak tespit edilemeyen kusurların SAR görüntüleme yoluyla tespit edilebilme potansiyeli irdelenmiştir. Ayrıca, derin öğrenme uygulamaları aracılığıyla arızalı nesnelerin otomatik tespiti için eşleştirilmiş filtre tabanlı bir SAR görüntü veri kümesi oluşturma yöntemi önerilmiştir. Bu sayede gerçek SAR ölçümlerinden elde edilen geniş ve çeşitli SAR görüntüleri içeren bir veri seti oluşturulmuş ve derin öğrenme şemalarının TM uygulamalarına uyarlanması sağlanmıştır. Bulgular, önerilen sistemin düşük maliyetli, yüksek çözünürlüklü 2B SAR görüntüleme için ve düşük radar yansıtıcılığına sahip minyatür malzemelerdeki minimal kusurların tespiti için önemini göstermektedir.Commercially available frequency-modulated continuous-wave (FMCW) millimeter-wave (mmWave) radars have become increasingly popular in radar imaging applications, coinciding with the recent advancements of mmWave technology. Thanks to the deep penetration and high-resolution capabilities of mmWave sensors, synthetic aperture radar (SAR) imaging applications adopting mmWave sensors hold great promise for defect detection in non-destructive testing (NDT). Nevertheless, in order to attain high-resolution imaging, proposed algorithmic, structural, and experimental solutions typically result in high cost and complexity issues. Moreover, detecting minimal defects on low reflective materials with optimized system parameters in terms of efficient processing as well as the automatic detection of defective objects are insufficiently addressed. This thesis introduces a deep learning-based automatic defect detection implementation from SAR imagery along with a high-resolution and cost-effective two-dimensional (2D) mmWave SAR imaging system with system parameters specifically optimized for use in NDT applications. We build a two-axis autonomous scanner integrated with a commercial-off-the-shelf (COTS) FMCW radar sensor operating between 77 and 81 GHz. Experimental measurements are conducted in a laboratory environment employing a single transceiver pair of the radar sensor. The system parameters that affect the reconstructed image quality including FMCW radar signal characteristics, spatial sampling intervals, and scanning apertures are optimized to obtain high resolution and low computational complexity. SAR imageries of different types and sizes of objects including low-reflective and defective ones are acquired and the impact of the system parameters on the image quality are investigated. Along with the effect of the target material's composition on SAR imaging, the potential for detecting visually undetectable defects on the target through SAR imaging is explored. Furthermore, a matched filter-based SAR image dataset creation method is proposed for the automatic detection of defective objects via deep learning applications. By this means, a dataset containing a wide and diverse range of SAR images obtained from real SAR measurements has been created, enabling the adaptation of deep learning schemes to NDT applications. The findings demonstrate the significance of the proposed system for low-cost, high-resolution 2D SAR imaging and the detection of minimal defects on miniature materials with low radar reflectivity
Effectiveness of Macroprudential Policies on Credit Surge and Stop Episodes
No full textTamgac Tezcan, Unay/0000-0001-8374-7019; Kenc, Turalay/0000-0001-5051-3726When faced with capital flow and credit growth waves in recent years, policymakers have relied upon macroprudential regulation. This paper sheds light on a relatively less-analyzed policy issue: how macroprudential regulatory measures mitigate extreme credit growth episodes. We use a dynamic panel data approach to estimate the impact of MaPPs on credit growth volatility and the likelihood of credit growth boom and bust episodes. We find that MaPPs reduce credit growth volatility in both advanced economies (AEs) and emerging market economies (EMEs). In addition, MaPPs help to prevent credit surges in EMEs and stops in AEs. Our results show that there is a strong link between net capital flows and credit growth stop episodes. Net capital flow surges trigger a credit surge for EMEs. This suggests that policymakers should consider both MaPPs and capital flow management measures when designing policies to mitigate the risks associated with these phenomena
Antiproliferative Activity of Platinum(ii) and Copper(ii) Complexes Containing Novel Biquinoxaline Ligands
Get PDFKayi, Hakan/0000-0001-7300-0325; Cetin, Yuksel/0000-0001-5101-3870; Ozalp Yaman, Seniz/0000-0002-4166-0529; Elbeshti, Hager/0000-0002-3027-0859Nowadays, cancer represents one of the major causes of death in humans worldwide, which renders the quest for new and improved antineoplastic agents to become an urgent issue in the field of biomedicine and human health. The present research focuses on the synthesis of 2,3,2MODIFIER LETTER PRIME,3MODIFIER LETTER PRIME-tetra(pyridin-2-yl)-6,6MODIFIER LETTER PRIME-biquinoxaline) and (2,3,2MODIFIER LETTER PRIME,3MODIFIER LETTER PRIME-tetra(thiophen-2-yl)-6,6MODIFIER LETTER PRIME-biquinoxaline) containing copper(II) and platinum(II) compounds as prodrug candidates. The binding interaction of these compounds with calf thymus DNA (CT-DNA) and human serum albumin were assessed with UV titration, thermal decomposition, viscometric, and fluorometric methods. The thermodynamical parameters and the temperature-dependent binding constant (KMODIFIER LETTER PRIMEb) values point out to spontaneous interactions between the complexes and CT-DNA via the van der Waals interactions and/or hydrogen bonding, except Cu(ttbq)Cl2 for which electrostatic interaction was proposed. The antitumor activity of the complexes against several human glioblastomata, lung, breast, cervix, and prostate cell lines were investigated by examining cell viability, oxidative stress, apoptosis-terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling, in vitro migration and invasion, in vitro-comet DNA damage, and plasmid DNA interaction assays. The U87 and HeLa cells were investigated as the cancer cells most sensitive to our complexes. The exerted cytotoxic effect of complexes was attributed to the formation of the reactive oxygen species in vitro. It is clearly demonstrated that Cu(ttbq)Cl2, Pt(ttbq)Cl2, and Pt(tpbq)Cl2 have the highest DNA degradation potential and anticancer effect among the tested complexes by leading apoptosis. The wound healing and invasion analysis results also supported the higher anticancer activity of these two compounds. Graphical Abstract Antitumor activity of biqunoxaline complexes
Power and Love versus Death : "Death Constant Beyond Love " by Gabriel Garc ía Márquez
No full textThis article analyses the philosophy and literary aesthetics of Gabriel García Márquez's political satire with reference to his short story, "Death Constant beyond Love."The analysis is based on the author's views concerning the common personality traits, actions and ends of tyrannical rulers made manifest in the main character of the story - Senator Onesimo Sanchez. It is observed that the philosopher-emperor Marcus Aurelius' meditations on the transience of existence, and the mortality of man serve as the backdrop to the power-drunk Senator's vain attempts to keep exercising his tyranny despite his awareness of his looming death. The story's central theme is that misused political power - no matter how wide its scope - is limited by man's transient corporeal existence, or by death, to put it more simply. The author's reflections upon dishonest politicians as fictionalized in the Senator display how corruption defiles each individual in society. The discussion on the nature and ramifications of man's boundless ambition for power also draws on Nietzsche's will to power/will to life equation, andFoucault's views on resistance-freedom/power proposition. © 2024 Kuǧu Tekin
The Relationship Between Non-Governmental Organizations and Sustainable Development Goals in Particular To Associations and Foundations
No full textBu yüksek lisans tezinde vergi kanunları, sürdürülebilir kalkınma hedefleri ve sivil toplum kuruluşları (STK'lar) Arasındaki ilişki incelenmektedir. 15 STK'nın son 5 yıllık mali verileri analiz edilerek STK harcamaları ile listelenen 17 Sürdürülebilir Kalkınma Hedefleri ile ilişki kurulmuştur. STK'ların sürdürülebilir kalkınmayı nasıl etkilediğini açıklığa kavuşturmaya yardımcı olacaktır. Çalışma, analiz sonuçlarını değerlendirerek STK'ların vergilendirme politikalarına farklı bir perspektif katmayı amaçlamaktadır.This master's thesis examines the relationship between tax laws, sustainable development goals and non - governmental organizations (NGOs). By analyzing the financial data of 15 NGOs fort he last 5 years a relationship was established between NGO expenditures and the 17 sustainable development goals listed. It will help clarify how NGOs influence sustainable development. The study aims to add a different perspective to the taxation policies of NGOs by evaluating the analysis results
An Enhanced Guided Stochastic Search With Repair Deceleration Mechanism for Very High-Dimensional Optimization Problems of Steel Double-Layer Grids
Get PDFFinding reasonably good solutions using a fewer number of objective function evaluations has long been recognized as a good attribute of an optimization algorithm. This becomes more important, especially when dealing with very high-dimensional optimization problems, since contemporary algorithms often need a high number of iterations to converge. Furthermore, the excessive computational effort required to handle the large number of design variables involved in the optimization of large-scale steel double-layer grids with complex configurations is perceived as the main challenge for contemporary structural optimization techniques. This paper aims to enhance the convergence properties of the standard guided stochastic search (GSS) algorithm to handle computationally expensive and very high-dimensional optimization problems of steel double-layer grids. To this end, a repair deceleration mechanism (RDM) is proposed, and its efficiency is evaluated through challenging test examples of steel double-layer grids. First, parameter tuning based on rigorous analyses of two preliminary test instances is performed. Next, the usefulness of the proposed RDM is further investigated through two very high-dimensional instances of steel double-layer grids, namely a 21,212-member free-form double-layer grid, and a 25,514-member double-layer multi-dome, with 21,212 and 25,514 design variables, respectively. The obtained numerical results indicate that the proposed RDM can significantly enhance the convergence rate of the GSS algorithm, rendering it an efficient tool to handle very high-dimensional sizing optimization problems.buda UniversityOpen access funding provided by & Oacute;buda University.Science Citation Index Expande
Tetkik Nedeni ile Verilen Açlık İsteminin Hasta Üzerindeki Etkileri: Tanımlayıcı Kesitsel Bir Araştırma
No full textAmaç: Hastanede yatan hastalarda laboratuvar ve radyolojik tetkik nedeniyle verilen açlık istemi süresinde atlanılan öğün sayısını ve hasta üzerindeki etkilerini belirlemektir. Gereç ve Yöntem: Araştırma tanımlayıcı ve kesitsel desende gerçekleştirildi. Araştırmanın örneklemini, Ekim-Aralık 2020 tarihleri arasında, iç hastalıkları servisinde yatan ve en az 8 saatlik açlık istemi verilen 18-65 yaş arasındaki 78 hasta oluşturdu. Araştırmanın verileri Hasta Tanıtım Formu, Numerik Şiddet Skalası, BARF Bulantı Ölçeği, Nutrisyonel Risk Skoru-2002, KATZ Günlük Yaşam Aktivitesi Ölçeği ve Beck Anksiyete Ölçeği aracılığı ile toplanmıştır. Bulgular: Araştırmaya katılan hastaların %11.54’ünün beslenme bozukluğu riskinin yüksek olduğu, tetkik nedeniyle ortalama 12.1 saat aç kaldığı ve bu süre içinde ortalama iki öğün kaçırdıkları belirlenmiştir. Hastaların NRS-2002 puan ortalaması 0.77±1.15, BARF Bulantı Ölçeği puan ortalaması 0.53±1.45, KATZ GYA puan ortalaması 0.32±0.987 ve Beck Anksiyete Ölçeği puan ortalaması ise 25.03±5.95 bulunmuştur. Sonuç: Araştırmamızda, laboratuvar ve radyolojik tetkik nedeniyle verilen açlık istemi süresinde atlanılan öğün sayısının, literatürde belirtilen süreden fazla olduğu ve hastaların susama, bulantı, yorgunluk, anksiyete yaşadığı belirlenmiştir. Çalışma sonuçlarının klinik alanda çalışan sağlık personeli ile paylaşılması ve hemşirelik uygulamalarına yansıtılması önerilmektedir
The Impact of Search Engine Presence on Individuals' Metacognitive Evolutions and Remembering
Get PDFBu tez, arama motoru erişilebilirliği ile bunun çeşitli bilişsel süreçler üzerindeki etkisi arasındaki karmaşık ilişkiyi araştırıyor; özellikle bilişsel özsaygı, bilme hissi (FOK), bulunabilirlik hissi (FOF), soruları yanıtlama isteği, tanınma ve bilgi saklama. Çalışma, arama motorlarına hem erişimin olduğu hem de erişimin olmadığı koşullar altında sunulan ve dijital araçların bilişsel işlevler üzerindeki etkisini incelemek için benzersiz bir mercek sağlayan, değişen zorluk seviyelerindeki genel bilgi soruları etrafında yapılandırılmıştır. Tek yönlü tekrarlanan ölçüm ANOVA'sını kullanan çalışma, arama motoru erişiminin katılımcıların bilişsel özgüvenleri ve üstbilişsel algıları üzerinde önemli etkilerini gösterdi. Bulgular, katılımcıların zorlu sorgularla ilgilenme konusunda daha yüksek bir isteklilik sergilediklerini ve arama motorlarına erişimleri olduğunda daha iyi tanınma ve bulunabilirlik duyguları sergilediklerini ortaya çıkardı. Bu, özellikle karmaşık görevlerde bilişsel güveni ve algılanan yeterliliği artırmada harici dijital araçların önemli rolünün altını çiziyor. Üstelik araştırma, soru formatlarına bağlı olarak performans ve akılda tutma açısından kayda değer farklılıkların altını çizdi; çoktan seçmeli sorular, özellikle zor içeriklerde, kısa cevaplı formatlara kıyasla daha yüksek akılda tutma oranları gösteriyor. Bu, hem ilk öğrenme hem de uzun süreli kalıcılık açısından çoktan seçmeli formatların yararları dikkate alınarak, eğitim ortamlarındaki değerlendirme stratejilerinin potansiyel olarak yeniden değerlendirilmesini önermektedir. Çalışma önemli bilgiler sağlarken, arama motoru erişim koşullarının ikili yapısının getirdiği sınırlamaları ve bulguların genellenebilirliğini etkileyebilecek bireysel farklılıkların etkisini de kabul ediyor. Bu yönler, bu dinamikleri daha incelikli ve çeşitli gerçek hayat senaryolarında keşfetmek için gelecekteki araştırmalara duyulan ihtiyacın altını çiziyorThis thesis investigates the intricate relationship between search engine accessibility and its impact on various cognitive processes, specifically focusing on cognitive self esteem, feeling-of-knowing (FOK), feeling-of-findability (FOF), willingness to answer questions, recognition, and information retention. The study was structured around general knowledge questions of varying difficulty levels, presented under conditions of both access and no access to search engines, providing a unique lens to examine the influence of digital tools on cognitive functions. Utilizing a one-way repeated measures ANOVA, the study demonstrated significant effects of search engine access on participants' cognitive self-esteem and metacognitive perceptions. Findings revealed that participants exhibited a higher willingness to engage with challenging queries and showed enhanced recognition and findability feelings when they had access to search engines. This underlines the pivotal role of external digital tools in boosting cognitive confidence and perceived competence, especially in complex tasks. Moreover, the research highlighted notable differences in performance and retention based on question formats, with multiple-choice questions showing higher retention rates compared to short-answer formats, especially for difficult content. This suggests a potential re-evaluation of assessment strategies in educational settings, considering the benefits of multiple-choice formats for both initial learning and long term retention. While the study provides significant insights, it acknowledges the limitations posed by the binary nature of search engine access conditions and the influence of individual differences, which may affect the generalizability of the findings. These aspects underscore the need for future research to explore these dynamics in more nuanced and varied real-life scenarios. This thesis contributes to the understanding of how digital tools, particularly search engines, intersect with human cognitive processes, offering practical implications for educational strategies and knowledge-based work environments in our increasingly digital worl