Atılım Academic Archive (Atılım University)
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Effect of Heat Treatment on the Hardness, Microstructure and Wear Resistance of Cast Fe-Mn-Al-Ni-C Lightweight Steel
Get PDFDüşük yoğunluklu çeliklere olan ilgi giderek artmaktadır. Bu tez çalışmasında döküm Fe-Mn-Al-Ni-C hafif çeliğinde çözündürme ve yaşlandırma ısıl işlemlerinin içyapı ve mekanik özellikler üzerindeki etkileri araştırılmıştır. Çözündürme işlemleri 850- 1150°C sıcaklık aralığında, 2, 4 ve 16 saatlik sürelerle uygulanmıştır. Takiben, 550°C ve 700°C'de 1, 4, 8 ve 16 saatlik yaşlandırma işlemleri gerçekleştirilmiştir. Isıl işlemlerin etkileri; optik ve elektron mikroskopisi, makro ve nano sertlik ölçümleri, aşınma testleri, EBSD ve XRD analizleri ile değerlendirilmiştir. Döküldüğü haliyle 477 HB olan sertlik, 1150°C'de 2 saat çözeltiye alma sonrası 258 HB'ye düşmüş, yaşlandırma ile %46-%88 oranında artış gözlenmiştir. Faz analizi sonucunda, as-cast numunelerde östenit, B2 ve κ-karbür fazları tespit edilirken, ısıl işlem sonrasında östenit fazı ve B2 fazının farklı morfolojilerdeki çökeltilerinin oluştuğu görülmüştür. Elde edilen sonuçlar doğrultusunda, 1150°C'de 2 saat çözündürme ve ardından 700°C'de 8 saat yaşlandırma işleminin, içyapı homojenliği ve aşınma direnci açısından en uygun ısıl işlem parametreleri olduğu belirlenmiştir.There is a growing interest in steels with low density. This thesis study investigated the effects of solutionizing and aging heat treatments on the microstructure and mechanical properties of cast Fe-Mn-Al-Ni-C lightweight steel with a density of 6.83 g/cm3. Solutionizing treatments were applied in the temperature range of 850-1150°C for 2, 4, and 16 hours. Subsequently, aging treatments were carried out at 550°C and 700°C for 1, 4,8, and 16 hours. The effects of the heat treatments were evaluated by optical and electron microscopy, macro and nano hardness measurements, wear tests, EBSD, and XRD analysis. The as-cast hardness of 477 HB decreased to 258 HB after 2 hours of solution treatment at 1150°C, and an increase of 46%-88% was observed with subsequent aging. XRD analyses revealed the presence of austenite, B2, and κ- carbide phases in the as-cast samples while heat treatment caused significant differences both in the relative amounts and morphologies of these phases. Based on the results, solution treatment at 1150°C for 2 hours followed by aging at 700°C for 8 hours was determined to be the most suitable heat treatment procedure in terms of microstructural homogeneity and wear resistance
Observation of Collider Neutrinos without Final State Muons with the SND at LHC Experiment
No full textWe report the observation of neutrino interactions without final state muons at the LHC, with a significance of 6.4σ. A dataset of proton-proton collisions at s=13.6 TeV collected by SND@LHC in 2022 and 2023 is used, corresponding to an integrated luminosity of 68.6 fb-1. Neutrino interactions without a reconstructed muon are selected, resulting in an event sample consisting mainly of neutral-current and electron neutrino charged-current interactions in the detector. After selection cuts, 9 neutrino interaction candidate events are observed with an estimated background of 0.32 events. © 2025 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3
Performance Evaluation of Campus-Scale Rainwater Harvesting: A Case Study at Atilim University
Get PDFBu çalışma, Ankara'da İncek Gölbaşı'nda yer alan Atılım Üniversitesi kampüsünde dağıtılmış yağmursuyu hasadı (RWH) sistemlerinin uygulanabilirliğini ve tasarımını incelemektedir. Artan su kıtlığına yönelik endişelerden yola çıkarak, bu çalışma RWH sistemlerinin özellikle peyzaj sulama gibi içme suyu dışı kullanımlarda geleneksel su kaynaklarına olan bağımlılığı azaltabilirliğini değerlendirmeyi amaçlamaktadır. Bu amaçla, yüzey akışı tahmini ve depolama altyapısını boyutlandırma için iki hidrolojik modelleme yaklaşımı kullanılmıştır: Toprak Koruma Servisi Eğri Sayısı (SCS-CN) yöntemi ve Storm Water Management Model (SWMM 5.2). Altı alt havzanın manuel sınırlandırılmasıyla birlikte, uzun dönem yağış verileri ve Harmonize Dünya Toprak Veritabanı temelli toprak özellikleri, akış ve sızma analizinin temelini oluşturmuştur. Depolama hacimleri, 17 yıllık bir dönemi kapsayan aylık kümülatif su fazlası verilerine göre hesaplanmış ve dinamik simülasyon kapasitesi nedeniyle SWMM tabanlı boyutlandırma önerilmiştir. Sonuçlar, önerilen RWH sistemlerinin üniversitenin toplam içme suyu dışı talebinin yaklaşık %26'sını karşılayabileceğini ortaya koymuştur. Bu bulgular, kampüs ölçeğinde su sürdürülebilirliği planlamasında RWH altyapısının entegrasyonunu desteklemekte ve yarı-kurak bölgelerde benzer kurumsal ortamlar için tekrarlanabilir bir modelleme çerçevesi sunmaktadır.This thesis investigates the performance of decentralized rainwater harvesting (RWH) systems at the Atılım University campus, in İncek, Gölbaşı, Ankara. Motivated by increasing water scarcity, the study aims to assess how effectively RWH systems can reduce institutional dependency on conventional water sources, particularly for non-potable uses such as landscape irrigation. To achieve this, two hydrological modeling methods—the Soil Conservation Service Curve Number (SCS-CN) method and the Storm Water Management Model (SWMM 5.2) are employed to estimate runoff and size storage infrastructure across six manually delineated subcatchments. Long-term precipitation data and soil characteristics from the Harmonized World Soil Database formed the basis of runoff simulation and infiltration analysis. Storage volumes calculated based on monthly cumulative surplus data over a 17-year period, with SWMM-based tank sizing selected for final recommendations due to its dynamic simulation capability. The results revealed that the proposed RWH systems could meet approximately 26% of the university's total non-potable water demand. These findings support the integration of RWH infrastructure in campus-scale water sustainability planning and provide a replicable modeling framework for similar institutional environments in semi-arid regions
The Association Between Digital Device Usage Behaviors and the Incidence of De Quervain’s Tenosynovitis Among University Students
No full textBackground: The extensive use of mobile and digital devices has been implicated in various musculoskeletal disorders, including de Quervain’s tenosynovitis (dQD), a condition affecting the thumb. Purpose: The present study investigates the relationship between digital device usage patterns and the prevalence of dQD among university students. Methods: A cross-sectional study was conducted with 508 participants (255 females and 253 males), collecting data on daily device use time, wrist positions, hand dominance, and stretching practices via a questionnaire. Data collection was carried out through a supervised, face-to-face survey. Diagnosis of dQD was determined using Finkelstein’s test, all data were analyzed using SPSS software. Results: Out of 508 participants, 187 (36.8%) tested positive for dQD, with 152 (95.6)% occurring in the dominant hand (p =.006, Cramér’s (Formula presented.) = 0.121). 250 participants used their devices with wrists in ulnar deviation (49.2%), which was strongly linked to a positive Finkelstein test result (p =.004, Cramér’s (Formula presented.) = 0.175). Finkelstein’s test showed increasing positivity with device use, ranging from 12.5% for < 2 hours to 46.2% for ≥ 8 hours, with a statistically significant association (p <.001, Cramér’s (Formula presented.) = 0.234). Device usage varied, with the highest test positivity rates among those using devices 6–8 hours per day suggesting a significant association with dQD (p =.001). No significant relationship was found between dQD and the practice of stretching or relieving movements (p =.146). Conclusion: The findings indicate that prolonged digital device usage, specific wrist positions such as ulnar deviation, and dominant-hand use are significantly associated with an increased risk of de Quervain’s tenosynovitis among college students. © 2025 Taylor & Francis Group, LLC.Science Citation Index Expande
Investigation of Human Herpesvirus 8 & Leishmania Species in Malignant Skin Tumours, Psoriasis, Actinic Keratoses, & Seborrheic Keratoses: a Single-Center Experience From Ankara, Turkey
Get PDFBackground & objectives: The role of human herpesvirus-8 (HHV-8) and Leishmania species in the aetiology of malignant skin tumours and proliferative skin diseases remains a topic of debate. This study aims to analyse formalin-fixed, paraffin-embedded (FFPE) skin biopsy samples using polymerase chain reaction (PCR) to determine whether skin lesions caused by HHV-8 and Leishmania spp. resemble malignant and proliferative skin diseases and assess the role of these pathogens in disease aetiology. Methods: In this retrospective, single-center observational study, skin biopsies were collected from 275 individuals diagnosed with malignant skin tumours, psoriasis, actinic keratoses, seborrheic keratoses, and chronic dermatitis. The presence of HHV-8 and Leishmania spp. in biopsy samples was evaluated Results: HHV-8 DNA was not detected in any of the samples using PCR. However, Leishmania spp. DNA was identified in 8.4 per cent of all samples (n=23). No positivity was observed in the control group (P=0.387). Leishmania spp. DNA PCR positivity was most frequently detected in psoriasis cases (32.4%), followed by actinic keratosis (AK) (8.7%), malignant skin tumours (4.2%), and seborrheic keratosis (SK) (3.8%). When the Leishmania positivity rate in individuals diagnosed with psoriasis was compared with that of the control group, the difference was found to be significant (P=0.002). The positivity rate in squamous cell carcinoma (SCC) (7.3%) was higher than in basal cell carcinoma (1.6%). Interpretation & conclusions: The findings in this study suggests that there is no relationship between malignant and proliferative skin diseases and HHV-8. However, Leishmania spp. DNA was detected in 8.4 per cent of all samples. Biopsy-archived samples may be preferred for the differential diagnosis of Leishmania in diseases that do not respond to treatment and in atypical clinical presentations.Science Citation Index Expande
Susamın (Sesamum İndicum L.) Kardiyovasküler Hastalıklarla İlişkisi
No full textSusam (Sesamum indicum L.), Pedaliaceae familyasına ait olan ve hem tropikal hem de subtropikal ülkelerde yetiştirilen bir bitkidir. Ana bileşenleri yağ ve proteinden oluşan susamın besin değeri yüksektir. Tohumları kalsiyum ve fosfor mineralleri ile A, E, B1, B2 ve B3 vitaminlerini içermektedir. Susam ayrıca fitosteroller, lesitin, doymamış yağ asitleri ve lignanlardan da zengindir. Susam yağının ana lignanları olan sesamin, sesamol ve sesamolin, antioksidanları artırarak hipertansiyona, hiperlipidemiye, lipit peroksidasyonuna ve inflamasyona karşı koruma sağlamaktadır. Susam yağının antihipertansif etkili olduğu ve tansiyon regülasyonu için gereken ilaç miktarını azalttığı yapılan çalışmalarda gösterilmiştir. Araştırmalarda susam yağının plazma kolesterolünü, düşük yoğunluklu lipoprotein kolesterolü ve trigliserit seviyelerini düşürdüğü bulunmuştur. Susam yağı ile ilgili yapılan araştırmalar, susamın ateroskleroz riskini azaltmada ve kardiyovasküler hastalıkları geciktirmede umut vaat ettiğini göstermektedir. Uygun fiyatlı ve doğal olduğu için susam yağının farmasötik tedavi olarak uygulanması amaçlanmaktadır. Bu derlemenin amacı, susamın kardiyovasküler hastalıklarla ilişkisini çeşitli çalışmalar ve mevcut literatür temelinde özetlemektir
A Neorealist Analysis of the Impact of the Organization of Turkic States on Turkey's Formation as a Regional Power
No full textBu tez, Türkiye'nin Türk Devletleri Teşkilatı (TDT) ile yürüttüğü iş birliğinin, ulusal çıkarlarını ve bölgesel güç olma hedeflerini gerçekleştirme sürecine etkisini neorealist kuram çerçevesinde analiz etmektedir. Neorealist kuram anarşik uluslararası sistemdeki güç ilişkilerinin devlet davranışlarını belirlemede en önemli unsur olduğunu ileri sürer (Waltz, 1979). Neorealist kuramın temelini oluşturan anarşik yapı ve güç dağılımı, Türkiye gibi bölgesel güçlerin konumu ve davranışlarında da değişiklikler ortaya çıkarmıştır. Tez bu değişiklikleri neorealist kuramın bölgesel düzeyde de nasıl işlev gördüğünü, Türkiye örneği aracılığıyla göstermeye çalışmaktadır. Neorealist Uluslararası sistemde güç dağılımının çok kutuplu bir yapıya evrilmesi, yalnızca küresel aktörleri değil, aynı zamanda bölgesel güçlerin konumlarını ve etki alanlarını da etkilemektedir. Değişen uluslararası koşullar, küresel ve bölgesel düzeyde değişen jeopolitik dinamikler doğrultusunda, Türkiye dış politikasında çok boyutlu açılımlara yönelmiş ve Batı merkezli stratejisini çeşitlendirme çabası içine girmiştir. 2009 yılında kurulan TDT; ortak tarih, dil ve kültür temelinde şekillenen TDT, üye ve gözlemci devletler arasında çok boyutlu iş birliğini hedefleyen bölgesel bir örgüt niteliğindedir. Türkiye, Türk Devletleri Teşkilatı içerisinde hem kurucu hem de yönlendirici bir aktör olarak, başta enerji olmak üzere karşılıklı ihtiyaçlarını üye devletlerle, iş birliği içinde karşılamayı, karşılıklı güveni pekiştirmeyi ve ekonomik ilişkileri geliştirerek bölge ülkelerinin kalkınmasına katkı sunmayı hedeflemektedir. Türkiye, bu süreçte hem kendi çıkarlarını gözetmekte hem de teşkilat içerisindeki anahtar rolünü pekiştirerek bölgesel caydırıcılığını artırmaktadır. Bu doğrultuda, Türk Devletleri Teşkilatı aracılığıyla Orta Asya, Kafkasya ve Avrasya'da daha etkin bir bölgesel aktör olma yönünde stratejik adımlar atmaktadır. TDT'nin, Türkiye açısından bir güç projeksiyonu aracı olarak işlev gördüğü ve bölgesel liderlik hedeflerine kurumsal bir zemin oluşturduğu ileri sürülmektedir. Bu tezde, nitel bir kuramsal çalışma olup, yöntem olarak ise durum analizi ve betimsel analizden yararlanılmıştır. Anahtar Sözcükler: Türkiye, Türk Devletleri Teşkilatı, Bölgesel Güç, Dış Politika, NeorealizmThis thesis analyzes the impact of Turkey's cooperation with the Organization of Turkic States (OTS) on the process of achieving its national interests and regional power goals within the framework of neorealist theory. Neorealist theory argues that power relations in the anarchic international system are the most important factor in determining state behavior (Waltz, 1979). The anarchic structure and distribution of power that form the basis of neorealist theory have also brought about changes in the position and behavior of regional powers such as Turkey. This thesis attempts to demonstrate how neorealist theory functions at the regional level through the example of Turkey. The evolution of power distribution in the neorealist international system into a multipolar structure has affected not only global actors but also the positions and spheres of influence of regional powers. In line with changing international conditions and shifting geopolitical dynamics at the global and regional levels, Turkey has shifted toward a multidimensional approach in its foreign policy and has embarked on efforts to diversify its Western-centric strategy. Established in 2009, the OTS is a regional organization that aims to promote multidimensional cooperation among member and observer states based on their shared history, language, and culture. Turkey, as both a founding and guiding actor within the Organization of Turkic States, aims to meet its mutual needs with member states, particularly in the field of energy, through cooperation, to strengthen mutual trust, and to contribute to the development of the region by developing economic relations. In this process, Turkey is both protecting its own interests and strengthening its key role within the organization, thereby increasing its regional deterrence. In this regard, it is taking strategic steps to become a more effective regional actor in Central Asia, the Caucasus, and Eurasia through the Organization of Turkic States. It is argued that the OTS functions as a power projection tool for Turkey and provides an institutional foundation for its regional leadership goals. This thesis is a qualitative theoretical study, utilizing situational analysis and descriptive analysis as its methodology. Keywords: Turkey, Organization of Turkic States, Regional Power, Foreign Policy, Neorealis
Low Signature UAVs: Radar Cross Section Analysis, Simulation, and Measurement in X-Band
No full textThe increasing prevalence of unmanned aerial vehicles (UAVs) is driving the development of radar systems capable of detecting them. This hampers the deployment of UAVs in military operations. While radar cross section reduction (RCSR) can be a valuable solution, the research on this subject is inadequate. This paper presents an RCSR approach adopting a shaping technique for UAVs, demonstrating the proposed approach's efficacy through simulations and actual experimental measurements performed in X-Band on a four-legged UAV model. Using electromagnetic computational instruments, the shaping is applied to the designed UAV model with parameter-based simulations, the simulated radar cross section (RCS) values are derived, and the comparative analysis of these instruments is conducted. Experimental measurements are performed in laboratory conditions using a vector network analyzer. Actual measurement results are validated by simulative findings with the examination of the influence of frequency, polarization, and aspect angle on RCS. The demonstrated measuring approach allows cost-effective and easily applicable research on RCS in X-Band, a commonly utilized frequency range in military. An average RCSR of 10 dBsm has been accomplished with the presented shaping approach.Science Citation Index Expande
Physics-Informed Neural Network for Bending Analysis of Twodimensional Functionally Graded Nano-Beams Based on Nonlocal Strain Gradient Theory
No full textThis paper presents the bending analysis of two-dimensionally functionally graded (2D FG) nano-beams using a physics-informed neural network (PINN) approach. The material properties of the nanobeams vary along their length and thickness directions, governed by a power-law function. Hamilton's principle, combined with the nonlocal strain gradient theory (NSGT) and Euler-Bernoulli beam theory, is employed to derive the governing equation for the bending analysis of 2D FG nanobeams. Due to the incorporation of size dependency and the variation of material properties in two dimensions, the governing equation becomes a high-order variable- coefficient differential equation, which is challenging, if not impossible, to solve analytically. In this study, the applicability of PINN for solving such high-order complex differential equations is investigated, with potential applications in nanomechanical engineering. In the PINN approach, a deep feedforward neural network is utilized to predict the mechanical response of the beam. Spatial coordinates serve as inputs, and a loss function is formulated based on the governing equation and boundary conditions of the problem. This loss function is minimized through the training process of the neural network. The accuracy of the PINN results is validated by comparing them with available reference solutions. Additionally, the effects of material distribution, power-law index (in both length and thickness directions), nonlocal strain gradient parameters, and material length scale parameters are investigated. This study demonstrates the versatility of the PINN approach as a robust tool for solving high-order differential equations in structural mechanics.Emerging Sources Citation Inde
Design Team Effectiveness and Architects' Personality Types
No full textArditi, David/0000-0002-1580-324X; Akcay, Emre Caner/0000-0003-4426-369XPurposeThe personalities of the design team members constitute one of the factors that influence team effectiveness. In this study, 223 members of the "American Institute of Architects" who are employed by the largest architectural design firms in the United States of America were categorized according to their personality types by using "The Enneagram Personality Type Model." Also, the respondents' opinions about eight team effectiveness outcomes were recorded in order to explore the relationship between team members' personality types and team effectiveness outcomes.Design/methodology/approachThe information was collected by a questionnaire where the first part included 144 pairs of statements that were used to identify respondents' personality types. The second part sought designers' opinions about the importance of eight team effectiveness outcomes rated on a Likert scale ranging from 1 to 5. The results were assessed by performing the Kruskal-Wallis test first and Dunn's post-hoc test with Bonferroni adjustment subsequently.FindingsThe findings highlight the significance of personality types in effective design teams. While Type 6 (loyalist and skeptic) and Type 3 (achiever and performer) architects prioritize team effectiveness the most, Type 7 architects (enthusiasts and epicureans) assign the lowest importance. However, the presence of Type 1 (reformist and perfectionist) and Type 8 (challenger and protector) architects within the same design team may involve challenges or conflicts.Originality/valueThe primary contribution of this study is that it is the first study in the construction management literature that utilizes The Enneagram of Personality Test to understand the relationship between team members' personality types and team effectiveness outcomes. This study is of direct relevance to practitioners and could be utilized in design team-building activities.Science Citation Index Expanded - Social Science Citation Inde