Atılım Academic Archive (Atılım University)
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Influence of the Heat Treatment on the Microstructure, Mechanical and High-Temperature Oxidation Behavior of Hastelloy X Alloy Fabricated Via Laser Powder Bed Fusion
No full textThe effect of building direction and heat treatment on the microstructure, mechanical properties, and high- temperature oxidation behavior of Hastelloy X (HX) alloy fabricated by the laser powder bed fusion (L-PBF) method was studied. Electron backscatter diffraction analyses revealed that the development of textured columnar grains with varying average grain sizes, boundary fractions, and dislocation densities induced the mechanical anisotropy observed in both horizontally and vertically fabricated samples. The yield strength (YS) values of the horizontally and vertically as-fabricated samples were determined as 605.7 +/- 15.9 MPa and 552.3 +/- 8.5 MPa, respectively. The post-processing heat treatment increased the ductility remarkably and reduced YS value down to similar to 445 MPa for all samples by the elimination of microstructural anisotropy and increased grain size subsequent to recrystallization. Oxidation tests conducted at 900 degrees C up to 100 h on as- fabricated samples exhibited severe intergranular oxidation, which was accompanied by the formation of large voids and microcracks as well as spallation of the oxide layer. In contrast, the heat-treatment improved the oxidation resistance of the alloy possibly due to the formation of uniform and dense Cr2O3 layer on the substrate surface.Science Citation Index Expande
On Quasi-Weibull Distribution
No full textExponential distribution together with a variety of its transformations is permanently used both in probability theory and related fields. The most popular one is the power transformation yielding the Weibull distribution. In this paper, the power distribution of exponential random variable is supplemented by a logarithmic factor leading to a new distribution called quasi-Weibull. This is a three-parameter distribution, where one parameter is inherited from the underlying exponential distribution, and the others originate from the transformation. The properties of the quasi-Weibull distribution are studied. Specifically, the impact of the parameters on the analyticity of characteristic function, the existence of the moment generating function, the moment-determinacy/indeterminacy and the behaviour of the hazard function are investigated.Science Citation Index Expande
Microstructure-Based Prediction of Mechanical Properties of Austempered Ductile Iron Using Multiple Linear Regression Analysis
No full textMultiple linear regression analysis (MLRA) was used to predict the mechanical properties of austempered ductile iron (ADI) including yield and tensile strength, uniform elongation, hardening exponent, as well as fracture energy by building a model that uses characteristic features of microstructural constituents as input parameters. The complex multi-scale microstructure of ADI, which is composed of spherical graphite particles over 10 mu m diameter; and an ausferritic matrix with sub-micron sized features, makes it ideal for prediction of mechanical properties. For that purpose, low alloyed ductile iron samples austempered between 300 and 400 degrees C for 45-180 min were tensile tested, and also multi-scale microstructural characterization were carried out using optical microscope, SEM, and EBSD technique. Moreover, a sensitivity analysis was performed to determine which microstructural parameter(s) each mechanical property is most sensitive to. The results show that tensile and yield strength are most sensitive to size and morphology of matrix phases. Moreover, the size and aspect ratio of acicular ferrite correlate well with those of high-carbon austenite; since both form during transformation of parent austenite into ausferrite during austempering treatment. Equiaxed parent austenite grains transform into ausferrite with acicular morphology during the austempering treatment; and presence of equiaxed austenite grains in the austempered samples indicates untransformed regions during austempering treatment. Ductility was found to be more sensitive to nodularity of graphite particles, and this sensitivity was attributed to the size difference between graphite particles and grain size of matrix phases
Feasibility Study of Chatter Suppression in Milling Through Internal Channels
No full textMilling chatter significantly affects machining productivity, and methods to eliminate chatter caused by milling cutter dynamics are limited due to space constraints and the rotation of the milling cutter. This study investigates the impact of fluid-induced damping effect on chatter stability in milling operations and proposes it as an easy to implement and effective method to improve chatter stability caused by a cutter's vibration mode. The approach utilises a viscous fluid, silicone oil, filled into internal coolant channel of the cutting tool to improve stability by increasing the damping. Both modal and milling tests were conducted for the tool with and without silicone oil. The results show that stability can be significantly increased by this method presenting it as a viable chatter suppression technique. The results show a significant improvement in stability by presenting the method as a practical and cost-effective chatter suppression solution. Its ease of implementation makes it attractive for industrial use.Hacettepe University Scientific Research Projects Coordination Unit [FKB-2024-21288]The authors thank MAL Manufacturing Automation Laboratories for providing CutPro's license. HD acknowledges support provided by Hacettepe University Scientific Research Projects Coordination Unit (FKB-2024-21288)
Savaş Tutsaklarının Kamuoyunda Dijital Gösterime Sunulmasından Doğan İnsancıl Hukuk Sorunları
No full textSosyal medya çağında savaş tutsaklarının dijital olarak gösterime sokulma uygulaması önemli bir tartışma konusu oluşturmaktadır. Savaş tutsaklarının dijital yayınlarla kişiselleştirilmeleri onların bedensel zarara uğramalarına yol açabileceği gibi onurlarına da zarar verme potansiyeline sahiptir. Bu durum savaş tutsaklarının sübjektif hakları ile enformasyona dayanan modern savaş yöntemlerinin örtüşmediğini göstermektedir. Savaş tutsaklarının tehlikeye maruz bırakılmasının ve onurlarının kırılmasının toplumun bilgilendirilmesi gerekçesi ile savunulması mümkün değildir. Savaş tutsaklarının teşhiri İnsancıl Hukukun ihlâli dışında insanlık dışı muamele olarak savaş suçu teşkil etmekte ve Uluslararası Ceza Hukuku sorumluluğuna da yol açabilmektedir. Uluslararası Ceza Mahkemesi Statüsü bedensel zarar vermemekle beraber nefret uyandıran sosyal değersizleştirmeye ve kişilik haklarını yok etmeye yol açan eylemlerin insanlık dışı muamele teşkil ettiğini, dolayısı ile savaş suçu oluşturabileceğini kabul etmektedir. Makale dijital yayınların İnsancıl Hukukta yol açtığı sorunlara ve bu bağlamda önerilen çözümlere ışık tutmaktadır
Physical and Mental Effects of Different Radical Prostatectomy Techniques on Urologic Surgeons
No full textObjective In this web-based international survey study, we aimed to show an association between physical exhaustion and patient, relatives, and employer-related mental stress for surgeons performing open radical prostatectomy (ORP), laparoscopic radical prostatectomy (LRP), and robot-assisted laparoscopic prostatectomy (RALP). Additionally, we also aimed to compare the outcomes of three approaches. Methods We sent a ten-question survey to the urologists performing ORP, LRP, and RALP via e-mail and social media. Only fully completed surveys were included in the study analysis. We asked questions about age, the preferred surgical approach for radical prostatectomy, frequency of weekly exercise, and their possible associations with physical exhaustion and musculoskeletal complaints. Results A total of 160 urologists completed the survey. The RALP group showed a lower physical exhaustion rate and increased eye strain (p 0.05). Conclusion Compared to ORP and LRP, physical exhaustion was lower in the RALP technique. Although the number of participants was limited, regular exercise weakly improved physical exhaustion and musculoskeletal complaints. We believe that regular sports activities by urologists dealing with LRP and RALP will help relieve physical discomfort.Turkish Association of Urology, Turkish Endourology SocietyAs authors, we would like to thank the Turkish Association of Urology, Turkish Endourology Society, and Turkurolap Education and Research Group for their support in reaching out to members of urologists
Workaholism and Sleep Disorders in Employees: The Moderator Roles of Workaholism in the Relationships Between Insomnia and Affective Symptoms
No full textObjective: Sleep disorders are a growing concern in occupational health due to their strong associations with emotional distress and impaired functioning. Employees with severe insomnia symptoms are at increased risk for affective symptoms such as anxiety and depression. However, this relationship may vary depending on work-related behavioral patterns. Workaholism, a compulsive drive to work excessively, may act as a moderator, intensifying the impact of sleep disturbances on affective symptoms and vice versa. This study aimed to assess sleep disorder risk among employees, examine differences in the severity of sleep disorders based on workaholism levels, and investigate the moderating roles of workaholism in the relationships between insomnia severity and affective symptoms. Materials and Methods: The sample consisted of 459 day-working employees (68.41% female, Mage =41.14, standard deviation =10.90) who completed measures of demographics, workaholism, and sleep disorders. Results: Results showed that 40.31% were at risk for at least one sleep disorder, and 28.98% for multiple. Compared to employees with lower workaholism, those with higher workaholism had significantly higher scores of breathing-related sleep disorder, insomnia, narcolepsy, restless legs/periodic limb movement disorder, and circadian rhythm sleep disorder. Moderation analysis revealed that workaholism significantly moderated the relationship between insomnia severity and affective symptoms, but not vice versa. As workaholism increased, the relationship between insomnia severity and affective symptoms became stronger. Conclusion: These findings suggest a high prevalence of sleep disorders among employees and that workaholism can exacerbate the affective burden of insomnia. Targeted interventions addressing both sleep health and workaholism may be critical for improving employee wellbeing
Tension between Security and Humanitarian Discourses in the EU's Migration Policies: The Case of Turkey
No full textAvrupa Birliği'nin göç politikalarında artan düzensiz göç ve güvenlik kaygılarıyla birlikte güç kazanan güvenlikleştirme söyleminin, insan hakları, mülteci koruması ve dayanışma gibi normatif değerlerle nasıl bir gerilim içine girdiğini Türkiye örneği üzerinden analiz etmektedir. 2015 mülteci krizi ve ardından gelen 2016 Türkiye-AB Mutabakatı, AB'nin güvenliği dışsallaştırma çabalarını ve Türkiye'yi bir tampon bölge olarak konumlandırma stratejisini açıkça yansıtırken, bu yaklaşım AB'nin kendi değerleriyle ciddi bir çelişki oluşturmaktadır. Norman Fairclough'un eleştirel söylem analizi yöntemiyle yürütülen bu çalışma, AB'nin göç politikalarında güvenlik ve insani söylemlerin nasıl şekillendiğini, bu söylemlerin politika yapım süreçlerine etkisini ve AB-Türkiye ilişkilerinde ortaya çıkan söylemsel çelişkileri incelemektedir. Güvenlik ve insani söylemler arasındaki dinamikler hem normatif değerler hem de stratejik çıkarlar açısından değerlendirilerek, bu politikalardaki gerilimlerin daha geniş bir bağlamda ele alınması amaçlanmıştır.This study how the securitization discourse in the European Union's migration policies, which has gained strength with increasing irregular migration and security concerns, has come into tension with normative values such as human rights, refugee protection and solidarity through the case of Turkey. The 2015 refugee crisis and the subsequent 2016 Turkey-EU Statement clearly reflect the EU's efforts to externalize security and its strategy of positioning Turkey as a buffer zone, an approach that poses a serious contradiction with the EU's own values. Using Norman Fairclough's critical discourse analysis methodology, this study examines how security and humanitarian discourses are shaped in the EU's migration policies, the impact of these discourses on policy-making processes and the discursive contradictions that emerge in EU-Turkey relations. By evaluating the dynamics between security and humanitarian discourses in terms of both normative values and strategic interests, it aims to address the tensions in these policies in a broader context
The Dual Function of Gendered Space in Atwood's The Handmaid's Tale and The Testaments: Control and Resistance in Domestic and Institutional Spaces
No full textBu tez, Margaret Atwood'un The Handmaid's Tale ve The Testaments adlı eserlerinde toplumsal cinsiyetli mekânlar hem ataerkil kontrol aracı olarak işlev gördüğünü hem de feminist direnişe zemin hazırladığını incelemektedir. Gilead'da iktidar mekân üzerinden işler: yatak odaları, mutfaklar, çalışma odaları ve kurumsal yapılar kadınları baskılamak ve disipline etmek amacıyla tasarlanır. Ancak Atwood'un anlatıları bu mekânların durağan olmadığını gösterir; kadınlar bu alanları hafıza, dayanışma ve hayal gücü yoluyla dönüştürür. Yakın okuma yöntemi ve feminist mekân kuramı kullanılarak yapılan bu çalışmada Giorgio Agamben'in egemenlik teorisi, Doreen Massey'nin mekânsal politikalara dair dinamik yaklaşımı, Daphne Spain'in toplumsal cinsiyet ve mimarlık üzerine çalışmaları ile Gaston Bachelard'ın mekân poetikasından yararlanılmıştır. Tez, Gilead'daki her bir mekânın ya baştan toplumsal cinsiyetli olarak inşa edildiğini ya da ataerkil düzenin etkisiyle bu niteliği kazandığını ortaya koyar. Ataerki, tıpkı egemen iktidar gibi, mekân üzerinden işlemekte; ayrıştırmakta, kontrol etmekte ve kimin nerede yer alacağını belirlemektedir. Bu çalışma, Gilead'daki direnişin sadece kaçışla değil, dönüşümle mümkün olduğunu savunur: Kadınlar, Ardua Hall'da Lydia Teyze'nin gizli arşiv faaliyetlerinde ya da Agnes'in ev içindeki sessiz başkaldırısında olduğu gibi, mekânları yeniden şekillendirerek özneleşir. Atwood'un eserleri, ataerkil mekânsal düzenin kırılganlığını ortaya koyarak en baskıcı ortamların bile direniş potansiyeli taşıdığını gösterir. Bu tez, feminist edebiyat çalışmalarına, mekânı geri kazanmanın gücü geri kazanmak anlamına geldiğini vurgulayarak katkı sunmaktadır.This thesis investigates how gendered spaces in Margaret Atwood's The Handmaid's Tale and The Testaments function as instruments of patriarchal control while simultaneously enabling feminist resistance. In Gilead, power operates spatially: bedrooms, kitchens, studies and institutional buildings are designed to confine and discipline women by embedding oppression into architecture. Yet Atwood's narratives reveal that these spaces are not static; women subvert them through memory, solidarity, and imagination. Using close textual analysis and feminist spatial theory, this study draws on Giorgio Agamben's theory of sovereignty, Doreen Massey's dynamic view of space, Daphne Spain's work on gender and architecture, and Gaston Bachelard's poetics of space to explore how control and resistance can exist in the same places. The thesis explains how each space in Gilead is either built to be a gendered space or becomes one through patriarchal power, which, like sovereign power, acts through space: dividing, controlling, and defining who belongs where. The study argues that resistance in Gilead is not just escape but transformation: women reshape and reclaim spaces to assert agency, whether through Aunt Lydia's secret use of Ardua Hall or Agnes's quiet rebellion within domestic walls. By exposing the fragility of patriarchal control over space, Atwood's work shows that even the most repressive environments hold the seeds of resistance. This thesis contributes to feminist literary studies by showing how reclaiming space becomes a powerful form of reclaiming power
Transoral Robotic Surgery (TORS) for Head and Neck Cancer in the Elderly Population: Functional Outcomes, Survival, and Complications
No full textObjective: To compare functional and oncologic outcomes in elderly (>= 70 years) and nonelderly (< 70 years) patients after transoral robotic surgery (TORS). Methods: A retrospective chart review was conducted on 114 patients who underwent TORS for head and neck squamous cell carcinoma between 2012 and 2022. Patient and tumor characteristics, perioperative details, complications, and survival parameters were analyzed. Swallowing function was assessed using the Functional Outcome Swallowing Scale (FOSS). Results: Of the 114 patients, 37 (32.5%) were elderly, and 77 (67.5%) were nonelderly. Elderly patients had higher comorbidity scores (p < 0.001). Oropharyngeal and oral cavity primaries were more common in the nonelderly group, whereas laryngeal primaries predominated in elderly patients (p < 0.01). Complication rates were higher in nonelderly (37.6%) than in elderly (18.9%) patients, though not statistically significant (p = 0.07). In elderly patients, FOSS scores showed no significant change preoperatively, postoperatively (< 3 months), or at the last follow-up (median 36 months). The nonelderly group experienced worse early postoperative FOSS scores compared to baseline but showed significant improvement, returning to preoperative levels by the last follow-up. Nonelderly patients had better FOSS scores at last follow-up compared to elderly patients (p = 0.014). Overall and recurrence-free survival outcomes were better in the nonelderly group, but disease-specific survival rates were comparable. Conclusion: Despite higher comorbidity rates in the elderly, TORS demonstrated favorable complication rates in the elderly population. Swallowing function returned to baseline after 3 months in both groups. TORS appears safe for elderly patients with comparable oncologic outcomes.Universite de Lausanne, as part of the Wiley - Universite de Lausanne agreement via the Consortium Of Swiss Academic LibrariesOpen access publishing facilitated by Universite de Lausanne, as part of the Wiley - Universite de Lausanne agreement via the Consortium Of Swiss Academic Libraries