İstanbul Gedik Üniversitesi Kurumsal Akademik Arşivi
DSpace@Gedik, İstanbul Gedik Üniversitesi tarafından doğrudan ve dolaylı olarak yayınlanan; kitap, makale, tez, bildiri, rapor, araştırma verisi gibi tüm akademik kaynakları uluslararası standartlarda dijital ortamda depolar, Üniversitenin akademik performansını izlemeye aracılık eder, kaynakları uzun süreli saklar ve etkisini artırmak için telif haklarına uygun olarak Açık Erişime sunar.
Güncel Gönderiler
Multifunctional SnO2-@ doped glass fiber-reinforced concrete: improved microstructure, mechanical, dielectric, and energy storage characteristics
(Elsevier Ltd, 2025) Ramazanoğlu, Doğu; Subaşı, Azime; Musatat, Ahmad Badreddin; Demir, Ahmet; Subaşı, Serkan; Maraşlı, Muhammed
This study explores SnO₂-based hybrid composite (SnO₂-@) doped glass fiber-reinforced concrete (GFRC) for enhanced dielectric, energy storage, and mechanical performance. Microstructural analysis confirmed SnO₂-@ promotes ettringite and calcium silicate hydrate (C-S-H) formation, improving matrix integrity. Aged samples exhibited a 650 % increase in surface roughness (Ra) and over 200 % higher Leeb hardness, demonstrating durability. Dielectric spectroscopy revealed frequency-dependent tunability: 1 % SnO₂-@ achieved a peak dielectric constant (ε' = 130 at 10 kHz), shifting to ε' = 140 at 100 kHz for 2–3 % doping. AC conductivity surged by 60 %, correlating with SnO₂-@-induced interfacial polarization and charge mobility. Energy storage capacity improved significantly, attributed to optimized dipole alignment and reduced leakage currents. Color stability remained robust (ΔE* ≤ 2.8 post-aging), ensuring aesthetic viability. These results position SnO₂-@-doped GFRC as a multifunctional material for smart infrastructure, integrating structural resilience, adaptive dielectric properties, and energy storage potential for next-generation urban applications.
Experimental and optimization study of nanofluid utilized PVT systems with hydrocarbon based PCM: an energetic-exergetic approach
(Elsevier Ltd, 2025) Kurtoğlu Sontay, Kübra; Öğüt, Elif; Ustaoğlu, Abid; Özkan, Doğuş; Kurşuncu, Bilal
Cooling of photovoltaic thermal (PVT) systems is crucial for enhancing electrical efficiency by reducing the operating temperature of photovoltaic modules. Elevated temperatures negatively affect the performance of PV cells, leading to a decline in energy conversion efficiency. Photovoltaic thermal (PVT) systems, hybrid technologies that generate electricity and heat, are crucial for efficient energy conversion. This study uniquely explores the performance of a PVT system by integrating phase change materials (PCMs) and nanofluids in PVT systems combined with optimization analysis. By combining these advanced cooling methods, both electrical and thermal efficiencies are significantly optimized, demonstrating the potential for improved energy conversion in PVT systems. Within this scope, three identical systems–water-cooled, nanofluid-cooled, and a combination of nanofluid cooling with PCM- were analyzed regarding electrical, thermal, and exergy efficiencies. Identical panels were placed side by side and tested. Additionally, an optimization analysis has been conducted to enhance the performance of each panel by evaluating the thermal and electrical efficiency values obtained from experimental data based on system parameters and levels. In addition, thermogravimetric analysis and differential scanning calorimetry were conducted to determine the melting point of the Hydrocarbon-Based PCM. Compared with traditional methods, these analyses conducted in conjunction with the experimental study provide a more reliable basis for performance evaluation studies of PVT systems. The results of the experimental study showed that Nanofluid-Integrated PVT with Hydrocarbon-Based PCM achieved 11.7 %, 11.6 % and 10.6 % higher electrical efficiency, overall exergy and electrical exergy respectively, compared to the water-cooling method. Additionally, a 6.6-fold increase in thermal efficiency and a 4.4-fold increase in overall efficiency were observed. Similarly, compared to the nanofluid cooling method, this combination provided 4.9 %, 5.9-fold and 3.47 % improvements in the electrical, thermal and overall exergy efficiencies metrics. The results of the optimization analysis revealed that the combination of PCM and nanofluids ensures greater stability in electrical efficiency values under high-temperature differences. It was also observed that solar irradiance is the most influential parameter affecting efficiency. The obtained results demonstrate that the nanofluid-cooled system integrated with PCM has a significant impact on enhancing the performance of PVT systems. The combined use of nanofluid and PCM considerably improves all efficiency parameters.
The Role of RRA heat treatments on corrosion behaviour of AlSi10Mg produced by additive manufacturing
(Elsevier B.V., 2025) Özer, Gökhan; Tütük, İbrahim; Cingöz, Umut Can; Koç, Ebubekir; Karaaslan, Ahmet
In this study, AlSi10Mg samples were produced using the Powder Bed Laser Fusion (PBLF) method with standard parameters. Specimens were retrogression and re-aging (RRA) heat-treated at various conditions. The effects of the RRA heat treatments on the properties of PBLF parts were examined by microstructure, electrical conductivity, and electrochemical corrosion tests. Microstructural properties were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy-dispersive X-ray (EDS) analysis. The results showed that after RRA heat treatment, the electrical conductivity of the material decreased slightly, and the corrosion resistance increased.
Analyzing traffic accident trends and correlations in Iraq: an investigative statistical approach
(American Institute of Physics, 2025) Hassooni, Dhuha Khalid; Ghasemlounia, Redvan; Hilal, Miami Mohammed; Al-Saffar, Zaid Hazim; Mohammed, Ghufran Taha
Traffic accidents are for two reasons, human-related and road-related structural behavior, two of which are in need of investigation. Herewith, this study embarks on an analysis of the dynamics of traffic accidents within Iraq, with a pronounced emphasis on statistical analyses concerning Baghdad, the capital city which is bearing the highest accident rates. An expansive dataset encompassing 10959 traffic incidents recorded over the year 2022 is utilized with this paper examining the distribution and nature of road accidents alongside the resultant degrees of injury. Through the deployment of Histograms and Q-Q Plots, the research confirms the normality of the data, paving the way for subsequent Pearson Correlation and ANOVA tests. These statistical methodologies reveal moderate, yet statistically insignificant, correlations between the nature of accidents and the characteristics of roads, with an F-statistic of 0.247 indicating no substantial effect of accident nature on the type of roads within Baghdad. Notably, the analysis extends to gender-referenced mortality records and root cause analyses that highlight significant seasonal fluctuations in accident occurrences, as well as pivotal gender disparities in road traffic incidents. The city-based accident records, detailed distributions of traffic accidents by nature, degree of injury, and recent accident trends, alongside statistical test visualizations, collectively underpin the analytical discourse. In conclusion, the paper asserts the critical necessity for targeted interventions and policy reforms aimed at mitigating these identified trends and contributing to the broader objective of enhancing road safety in Iraq.
Performance of ECC mortar containing limestone powder as a full replacement of fine aggregate
(American Institute of Physics, 2025) Mohammed, Ghufran Taha; Abed, Jasim Mohammed; Hassooni, Dhuha Khalid
Limestone powder (LP), derived from marble dust and stone waste, was utilized as a sand substitute in engineering cement compounds (ECC). This readily available material is a by-product of industrial waste from local quarries and stone cutting, and it was sourced from Mosul factories for this research. The study aimed to fully replace the fine aggregate in ECC with LP. Experimental findings demonstrated that LP had an impact on the hardening and drying process, resulting in longer drying and hardening times. Consequently, there was a decrease in the initial compressive and tensile strength. However, the use of finer LP compensated for this effect. Seven mixtures were tested with varying LP/PC (Portland Cement) replacement ratios (0.75, 1, 1.5, 2, 2.5, 3, and 3.5). The best results were obtained with mixture M5. The addition of LP led to an increase in compressive strength, with values reaching up to 32.40 MPa at 28 days. Finer LP particles further enhanced this effect. Conversely, increasing the LP/PC replacement ratio resulted in a reduction in tensile strength due to the higher water-cement ratio. The tempering effect contributed to an enhancement of 3.92 MPa in tensile strength. The incorporation of LP significantly reduced the environmental impact by decreasing the demand for natural resources. The use of limestone in the ECC mortar gave good results for tests of the mechanical properties of the mortar, as this is considered a viable option for use in building, construction, and repair operations. It is recommended that further improvements, research, and studies be conducted to improve the formulations and types of such alternative mortar.
