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Investigation of flow and heat transfer in double-glazed windows under vertically oscillating conditions
No full textThe flow and heat transfer characteristics in double-glazed window under various vertically oscillating conditions are investigated. A comprehensive parametric numerical study has been conducted to investigate the flow and conjugate heat transfer of natural convection in three gaps of double-glazed windows which are L = 6 mm, 12 mm and 18 mm. Indoor and outdoor temperatures are kept constant, with convective boundary conditions are applied to both inner and outer glaze surfaces to ensure realistic conditions. To determine sinusoidal oscillation conditions in vertical direction, four different frequencies (f = 1 Hz, 2 Hz, 3 Hz, and 6 Hz) and six different amplitudes (A = 0.5 g, 1 g, 1.5 g, 2 g, 3 g, and 4 g) are applied. These vertical oscillations were considered to model the natural convection within double-glazed windows inside a moving bus and/or ship. The numerical results present streamline and isotherm contours, revealing flow and heat transfer within the glazed window gap. Velocity and temperature variations over time are displayed, along with the time-averaged Nusselt number for determined gaps, frequencies and amplitudes. The results show that, all cases of L = 6 mm produced conduction heat transfer (Nu = 1), and with an increase in the gaps, convection heat transfer become dominant. An amplitude of 3 and 4 g, and frequency of 1 and 2 supports the more convective heat transfer
Effects of Pressurized Water Aging on Reciprocating Friction and Wear of FDM 3D-Printed PLA and Glass Fiber Reinforced PLA Composites
No full textThis study evaluates 10 bar water aging effects on reciprocating tribology of FDM-printed PLA and PLA with 10 and 15 wt.% glass fiber (GF). Water uptake was Fickian, and saturation mass rose from 0.0845 g (PLA) to 0.1625 g and 0.295 g (10 and 15 wt.% GF). Reciprocating tests at 40 N over 100 m at 0.5 and 1 Hz showed immersion time drives coefficient of friction (COF) and wear. At 0.5 Hz, neat PLA stabilized at COF 0.65 to 0.70 but increased to about 0.75 to 0.80 after 7-day; PLA + 10 wt.% GF reached about 0.80 to 0.82 after 14-day to 28-day. GF reduced unaged wear depth from about 125 µm to about 85 to 96 µm, yet 28-day aging increased depths to about 129 to 132 µm for both GF levels at 0.5 Hz. At 1 Hz, neat PLA peaked at about 235 to 240 µm depth after 7-day, whereas 15 wt.% GF reached about 160 µm after 28-day. Factorial analysis showed that wear scar width was primarily influenced by immersion time, accounting for 76.02% of the variation in the data, clearly evidencing strong dependence on the environment. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC), glass transition temperature (Tg), and the melting temperature (Tm) support the occurrence of a transition from volume to interface-dominated damage with aging, while Tg and Tm remain unaffected.</p
Effect of irrigation solution temperature during pars plana vitrectomy on early postoperative choroidal vascularity
No full textPurpose: This study aims to compare the effects of cooled versus room-temperature irrigation solutions on preoperative and early postoperative choroidal vascularity in patients undergoing pars plana vitrectomy (PPV) for idiopathic epiretinal membrane (ERM) peeling. Methods: In this prospective, randomized, comparative study, 54 patients underwent standard 23-G PPV performed by a single surgeon. During the procedure, 27 patients received cooled irrigation solutions (Group 1), while the remaining 27 patients were treated with room-temperature irrigation solutions (Group 2). Central macular thickness (CMT), subfoveal choroidal thickness (SFCT) and choroidal vascularity index (CVI) were measured preoperatively and five to ten minutes postoperatively in both groups. The preoperative-to-postoperative changes within each group and the differences between the two groups were analyzed. Results: In Group 1, significant differences were observed in both SFCT and CVI values between the preoperative and postoperative measurements (p = 0.002 and p = 0.002, respectively), whereas the mild reduction in CVI in Group 2 (p = 0.012) did not remain statistically significant after Bonferroni correction. However, no statistically significant differences were found in the magnitude or percentage of preoperative-to-postoperative changes between the groups (p > 0.05). A two-way repeated measures ANOVA revealed significant reductions in CMT, SFCT, and CVI following PPV in both groups (p < 0.05). Conclusion: PPV caused an early postoperative decrease in choroidal perfusion, which was significant in the cold irrigation group. However, there was no significant difference between cooled and room-temperature irrigation solutions
Effect of cryogenic treatment on the aging kinetics and properties of CuNiSiCr alloy
No full textIn this study, a commercially extruded CuNiSiCr alloy was subjected to a solution treatment at 900 degrees C for 60 min, followed by rapid cooling using conventional water quenching and cryogenic cooling methods. The samples were then aged at 450 degrees C for 0-240 min. Metallurgical analyses revealed the presence of Ni/Cr-rich metal silicides within the alpha-Cu matrix, and it was determined that Cr-rich precipitates did not fully dissolve during the solution treatment due to their high-temperature stability. Electrical conductivity measurements showed a decrease in conductivity values after quenching in the supersaturated matrix, but significant increases in conductivity were observed with aging time. Cryogenic cooling accelerated the precipitation kinetics, enabling the attainment of higher conductivity (24.09 MS m-1) and hardness (247 HV) values in a shorter time. Using the Avrami kinetic model, precipitation volume fractions and phase transformation rates were calculated, confirming that cryogenic cooling accelerates the aging process. The findings demonstrate that cryogenic cooling combined with appropriate aging optimizes the microstructure and phase distribution of the CuNiSiCr alloy, improving key properties such as electrical conductivity and mechanical hardness, thereby providing superior performance for commercial applications
Utilizing fractional time derivative of instantaneous frequency for the evaluation of wedge and thin-layer structures in measured and modelled GPR data
No full textThis study proposes a novel approach for evaluating wedge and thin-layer structures in 2-D ground-penetrating radar (GPR) data by computing instantaneous frequency (IF) using fractional time derivatives. The Caputo fractional differential operator is employed as a more suitable alternative to standard IF methods for resolving thin layers and wedge geometries. To demonstrate the method's effectiveness, 2-D forward modelling based on the finite-difference time-domain (FDTD) technique was used to generate synthetic radargrams for various scenarios. Models included thin layers with thicknesses of 5, 7, and 10 cm, and a wedge with thickness varying from 0 to 20 cm, each with distinct relative dielectric permittivity values. Synthetic modelling was conducted using a 300 MHz Ricker wavelet to evaluate fractional instantaneous frequency (FIF) performance under moderate frequency conditions. FIF was computed for each trace in the synthetic radargrams at different derivative orders. The FIF-calculated radargrams of the experimental data revealed enhanced interpretation of the wedge structure, particularly in its thinner regions. To validate these findings, GPR measurements were conducted using a high-frequency 2 GHz antenna on three laboratory models: a distilled-water-filled wedge, a finer-sand wedge, and a thin-layer structure. The FIF-calculated radargrams revealed enhanced interpretation of wedge and thin-layer structures, particularly in thinner regions. Overall, the results demonstrate that FIF analysis significantly improves boundary detection and thickness estimation in both synthetic and real GPR data. This technique offers valuable advantages for non-destructive subsurface evaluation in geological, archaeological, engineering, and environmental applications
Kolonoskopi Sırasında Sanal Gerçeklik Uygulamasının Ağrı Anksiyete ve Utanmaya Etkisi
No full textAmaç:Bu çalışma, genel anestezi uygulanmadan yapılan kolonoskopi işlemi sırasında sanal gerçeklik(VR) teknolojisi ile görsel dikkat dağıtma yönteminin ağrı, anksiyete ve utanma duygusu üzerine etkisinideğerlendirmek amacıyla gerçekleştirildi. Ayrıca kolonoskopi sırasında anksiyete yönetimindefarmakolojik olmayan yenilikçi bir girişim olarak VR’nin klinik uygulamalarına katkısı incelendi.Yöntem: Araştırma, ön test–son test kontrol gruplu randomize kontrollü blok tasarımda planlandı.Çalışmaya 18–65 yaş aralığında, ilk kez kolonoskopi yapılan ve genel anestezi uygulanmayan toplam44 hasta dâhil edildi. Katılımcılar blok randomizasyon yöntemiyle VR müdahale grubu (n=15) vekontrol grubu (n=19) olarak iki gruba ayrıldı. Girişim grubundaki hastalara işlem öncesi ve sırasındaVR gözlüğü aracılığıyla sanal gerçeklik videosu izletildi; kontrol grubuna herhangi bir girişimuygulanmadı. Veriler Kişisel Bilgi Formu, Spielberger Durumluk-Sürekli Kaygı Envanteri (STAI),Görsel Analog Ölçek (VAS) ve Kolonoskopi Utanma Ölçeği kullanılarak toplandı. Verilerin analiziIBM SPSS 30 programında gerçekleştirildi.Bulgular: Araştırmanın ön çalışma bulgularına göre; Deney ve kontrol grubu arasında yaş, BKI,cinsiyet, medeni durum ve eğitim durumu özellikleri açısından istatistiksel olarak anlamlı farkbulunmadı, gruplar benzerdi (p>0,05). Deney ve kontrol gruplarının işlem öncesi süreklilik kaygıpuanları arasında anlamlı fark saptanmadı (p>0,05). İşlem öncesi utanma puanı deney grubunda kontrolgrubuna göre daha yüksekti (p=0,024). Her iki grupta da işlem öncesi ve sonrası durumluk kaygıpuanlarında ve gruplar arasında anlamlı fark bulunmadı (p>0,05). Buna karşın, her iki grubun işlemöncesi ve sonrası utanma ve anksiyete puanlarında anlamlı azalma gözlendi (p<0,001), bu azalma deneygrubunda kontrol grubuna göre daha belirgin bulundu. Ayrıca işlem sonrası anksiyete ve ağrı puanlarıdeney grubunda kontrol grubuna kıyasla anlamlı düzeyde daha düşük saptandı (p<0,001).Sonuç ve Öneriler: Bu araştırmanın bulguları, VR müdahale grubunda özellikle işlem sonrasıanksiyete, utanma ve ağrı düzeylerini azaltmada kontrol grubuna kıyasla daha etkili olduğunu vebireylerin psikolojik konforunu artırdığını göstermektedir. Grupların demografik ve işlem öncesi kaygıdüzeyleri açısından benzer olması, gözlenen olumlu etkinin uygulanan girişime bağlı olduğunu desteklemektedir. Gelecek çalışmalarda, bu girişimin farklı klinik örneklemlerde, daha geniş hastagruplarında ve uzun dönem etkilerini değerlendirecek şekilde çok merkezli randomize kontrollüçalışmalarla incelenmesi önerilir. İşlem öncesi ve sonrası dönemde hastaların anksiyete, utanma ve ağrıdüzeylerini azaltmak amacıyla, bu çalışmada kullanılan girişimin standart bakım uygulamalarınaentegre edilmesi ve sağlık profesyonellerine yönelik uygulama rehberlerinin geliştirilmesi önerilir.Bu çalışma Kocaeli Üniversitesi Bilimsel Araştırma Projeleri Koordinasyon Birimi tarafından TAA2025-4284 nolu proje kapsamında desteklenmiştir. Objective: This study was conducted to evaluate the effect of virtual reality (VR) technology as a visualdistraction method on pain, anxiety, and embarrassment during colonoscopy performed without generalanesthesia. In addition, the contribution of VR as an innovative non-pharmacological intervention inanxiety management during colonoscopy to clinical practices was examined.Method: The research was planned in a randomized controlled block design with pre-test–post-testcontrol groups. A total of 44 patients aged 18–65 years who underwent colonoscopy for the first timeand did not receive general anesthesia were included in the study. Participants were divided into twogroups using block randomization: VR intervention group (n=15) and control group (n=19). Patients inthe intervention group were shown a virtual reality video via VR glasses before and during theprocedure; no intervention was applied to the control group. Data were collected using a PersonalInformation Form, the Spielberger State-Trait Anxiety Inventory (STAI), the Visual Analog Scale(VAS), and the Colonoscopy Shyness Scale. Data analysis was performed using IBM SPSS 30 software.Findings: According to the preliminary findings of the study; there were no statistically significantdifferences between the experimental and control groups in terms of age, BMI, gender, marital status,and education level; the groups were similar (p>0.05). No significant difference was found between theexperimental and control groups in pre-procedure trait anxiety scores (p>0.05). Pre-procedure shynessscores were higher in the experimental group than in the control group (p=0.024). There was nosignificant difference between the pre- and post-procedure state anxiety scores in either group (p>0.05).However, a significant decrease was observed in both pre- and post-procedure shyness and anxietyscores in both groups (p<0.001), and this decrease was more pronounced in the experimental group thanin the control group. Furthermore, post-procedure anxiety and pain scores were found to be significantlylower in the experimental group compared to the control group (p<0.001).Conclusion and Recommendations: The findings of this study show that the VR intervention group ismore effective than the control group in reducing post-procedure anxiety, embarrassment, and painlevels, and increases the psychological comfort of individuals. The similarity of the groups in terms of demographics and pre-procedure anxiety levels supports the idea that the observed positive effect is dueto the intervention applied. In future studies, it is recommended that this intervention be examined inmulticenter randomized controlled trials in different clinical samples, in larger patient groups, and toevaluate its long-term effects. In order to reduce the anxiety, embarrassment, and pain levels of patientsin the pre- and post-procedure periods, it is recommended that the intervention used in this study beintegrated into standard care practices and that application guidelines for healthcare professionals bedeveloped. This study was supported by the Kocaeli University Scientific Research ProjectsCoordination Unit under project number TAA-2025-4284.</p
Long-Term endocrine outcomes with special emphasis on the gonadal impact of acute lymphoblastic leukemia treatment in females
No full textThis study aims to explore the long-term endocrine and gonadal effects of chemotherapy and radiotherapy in female acute lymphoblastic leukemia (ALL) patients. A cohort study included girls diagnosed with ALL and treated between 2000 and 2020. Patients with at least 2 years elapsed since treatment completion were included. Endocrinological evaluations included anthropometric measures and pubertal status, as well as fasting insulin, glucose, lipid levels, and hormone assessments for adrenal, and thyroid functions. Reproductive functions were evaluated based on gonadotropin, estradiol, and anti-Müllerian hormone (AMH) levels. A total of 51 female patients were included. At the time of study participation, the mean age was 14.7 years, and the mean time since treatment completion was 9.4 years. At least one endocrine disorder was present in 39.2% of participants, with dyslipidemia, insulin resistance, and obesity being the most common. Low AMH levels (< 1.1 ng/dL) were found in 41.6%, particularly in those who underwent bone marrow transplantation. A significant positive correlation was found between the time elapsed since treatment and AMH levels (p < 0.001, r = 0.612), while age at diagnosis, risk group (standard, intermediate or high risk), and cranial radiotherapy showed no significant associations. A substantial proportion of ALL survivors developed endocrine complications, with ovarian reserve compromised in over 40% of cases. Notably, this is the first cohort study to demonstrate a significant positive correlation between AMH levels and the time elapsed since treatment, suggesting a potential for gonadal recovery except in those exposed to intensive chemotherapy or transplantation
An efficient surface defect classification using UNET-based feature extraction and optimized feature selection
No full textAccurate detection of surface defects is crucial due to the complex background textures on material surfaces, significant intra-class defect variations, and the presence of subtle texture defect regions. This study introduces an innovative approach that employs the UNET model to extract image features from surface defect detection datasets. The extracted features are then selected using the African Vultures Optimization Algorithm (AVOA), Honey Badger Algorithm (HBA), and Whale Optimization Algorithm (WOA) metaheuristic algorithms, with classification carried out using Random Forest (RF) and Gradient Boosting (GB). The proposed approach is validated on the DAGM 2007 and KollektorSSD2 datasets. The experimental results show that the proposed approach is both efficient and effective, significantly outperforming supervised methods and achieving performance comparable to others. Specifically, it achieves accuracy rates of 82% with WOA + GB and 97% with AVOA + RF on the DAGM 2007 and KollektorSSD2 surface defect detection datasets, respectively. Additionally, an ablation study was also performed with feature extractors and classification algorithms, demonstrating that the proposed hybrid model achieves superior classification accuracy compared to state-of-the-art surface defect classification approaches. These findings highlight the robustness and adaptability of the proposed method, providing an efficient and dependable solution for surface defect classification in industrial settings
