Cemaloglu, Fulya; Özlü, Bares; Demir, Halil

In this study, the effects of different heat treatment conditions applied to Inconel 718 alloy produced by the Selective Laser Melting (SLM) method on microstructure, surface roughness, dimensional accuracy, and geometric tolerances were experimentally investigated. Five specimens with nominal dimensions of 22 & times;22 & times;55 mm were produced; one was kept as the as-built sample, while the others were subjected to heat treatment under the conditions of 980-1.5h, 800-1h, 800-4h, and 800-32h. Microstructural analyses indicated that the heat treatments reduced the melt pool traces and resulted in a more homogeneous structure. Surface roughness measurements showed that the average roughness value of the as-built sample was 12.946 & micro;m, whereas roughness decreased under all heat treatment conditions. The lowest value was measured as 10,065 & micro;m after aging at 800-32h, corresponding to an improvement of 22,25 %. In terms of dimensional accuracy, the lowest deviations were obtained in the as-built specimen. In contrast, under the 800-32h condition, maximum deviations of up to 0.86% were detected in certain dimensions. Parallelism tolerances increased after long-term aging, whereas the lowest deviation in perpendicularity tolerance was obtained under the 980-1.5h condition. The findings indicate that while long-term aging improves surface quality, it may adversely affect certain dimensional and geometric characteristics.

Çolak, Andac Batur; Kilinç, Cuma

This article examines the fundamental requirements for effective thermal management of batteries, particularly in high-energy density applications such as electric vehicles and energy storage systems. A unique method is introduced that utilizes a triple periodical minimal surface pore structure in liquid cooling channels to improve heat dissipation and temperature homogeneity in battery packs. Experimental validation and optimization via artificial neural networks are used to evaluate and improve thermal performance, focusing on critical metrics such as maximum temperature and temperature difference within the battery system. Artificial neural network models demonstrated model reliability, exhibiting ideal prediction accuracy with low mean square error values of 1.29E-05 and 9.87E-06, and a correlation coefficient of 0.99999. AThis work builds upon previous attempts by combining an innovative structural design with machine learning, aiming to provide a robust and data-driven solution that aligns cooling efficiency with structural integrity. The novelty of the study lies in its dual experimental machine learning approach, which provides a foundation for improved predictive control in battery temperature management systems with high accuracy and minimal resource requirements.

Çelik, Alper; Anil, Ozgur; Mercimek, Omer; Akkaya, S. Tuna; Turan, A. Ihsan

Masonry structures are buildings whose load-bearing system consists of vertical walls made of different units such as bricks, aerated concrete or natural stones. Masonry structures are quite common because they can be built quickly and economically with the use of local materials without requiring skilled labor. In the design of masonry structures and in the analyses of existing masonry structures, it is very important to determine the mechanical properties of the material accurately and to use them in the calculation models created with the micro model technique. In this study, the mechanical behaviour of hollow brick, clay brick and aerated concrete masonry units under uniaxial compressive loading was investigated experimentally for the purpose of masonry analysis. Using the experimental results, the concrete damage plasticity (CDP) model is proposed for the clay-based brick material for applications to be analysed by micro modelling technique in finite element software. The method used in the study will provide light for experimental studies to be carried out to determine the mechanical properties of different types of masonry units and to reflect them to the analysis models.

Güncü, Arzu; Soyluk, Asena; Çelik, Alper; Mutlu, Erkan Okay

In this study, the earthquake behaviour of the historical cadurcu Bath in Erzincan, which is located on the North Anatolian Fault, the most active fault line of Turkey, was investigated. This historical masonry structure has preserved its structural integrity despite being exposed to two earthquakes of magnitude 7.8 in 1939 and 6.7 in 1992. In accordance with the architectural survey studies, the historical building was modelled. According to the results of response spectrum analysis, stress and displacement distributions and modal characteristic parameters of the structure were evaluated. When the analysis results of the models created with the solid model technique and the shell model technique are compared, it is concluded that the shell modelling technique is safe in such studies, considering the analysis time and modelling difficulty. According to the results of the analyses, considering the stress distribution in the historical building elements, it is seen that the configuration characteristics of historical masonry structures are important in earthquake resistance like other building systems.

Seyhan, Aslihan Kurnuc; Uzun, Sinem; Coskun, Salih

A domestic solar water heating system using a flat plate collector is modeled for the domestic hot water requirement of a residential unit in Ankara, Turkey. The necessary design parameters were determined and the analysis was carried out using the TRNSYS simulation program. In the modeled system, the domestic water temperature was determined as 55 degrees C and water withdrawals were carried out at different flow rates during the day according to the usage intensity. The water withdrawal rates were determined as 80 kg/h between 07.00-09.00, 100 kg/h between 12.00-13.00 and 50 kg/h between 17.00-22.00. According to the results obtained, the designed system was able to meet the hot water need in summer and winter months by using solar energy through auxiliary heaters. While the collector efficiency reached its highest value with 40% in September, it reached the lowest efficiency value with 8% in December.

Uzun, Sinem; Seyhan, Aslıhan Kurnuç; Coşkun, Salih

Düz plaka kollektör kullanan bir güneş enerjili su ısıtma sistemi, Türkiye'deki Ankara ili için, bir konut biriminin kullanım sıcak suyu ihtiyacı için modellenmiştir. Gerekli tasarım parametreleri belirlenmiş ve analizler TRNSYS simülasyon programı kullanılarak gerçekleştirilmiştir. Modellenen sistemde kullanım suyu sıcaklığı 55 °C olarak belirlenmiş ve kullanım yoğunluğuna göre gün içerisinde farklı debilerde su çekimleri gerçekleştirilmiştir. Su çekim hızları 07.00-09.00 saatleri arasında 80 kg/saat, 12.00-13.00 saatleri arasında 100 kg/saat ve 17.00-22.00 saatleri arasında 50 kg/saat olarak belirlenmiştir. Elde edilen sonuçlara göre tasarlanan sistem, yardımcı ısıtıcılar vasıtasıyla güneş enerjisi kullanılarak yaz ve kış aylarındaki sıcak su ihtiyacını karşılayabilmiştir. Kolektör verimi Eylül ayında %40 ile en yüksek değerine ulaşırken, Aralık ayında %8 ile en düşük verim değerine ulaşmıştır.

Uzun, Sinem; Genç, Yasin; Acir, Adem

When examining the safety and design features of nuclear power reactors, its thermal performance in addition to neutronic characteristics is important. In this study, the neutronic and thermal performances of VVER-1000 reactor with two different fuel assembly arrangements were examined. Those fuel assemblies named as YD1 and YD2 are composed of 3.7% enriched LEU and 3.6% enriched LEU with 4% Gd2O3 uranium-gadolinium (UGD) and 2%, 3%, 4.2% Pu and 3.6% enriched LEU with 4% Gd2O3 (MOXGD), respectively. The effects of using UGD and MOXGD fuel assembly arrangements on criticality and isotope transformations according to burnup rate were investigated by means of MCNP5 and MONTEBURNS2.0 nuclear code, correspondingly the temperature and enthalpy changes of the coolant along the hot channel were examined with the help of the COBRA-IV PC thermal analysis code. The results obtained from this study were compared with similar studies in the literature and it was observed that the obtained findings were in accordance with the literature.

Uzun, Sinem; Genç, Yasin; Acir, Adem

Thermal analysis is of great importance when examining the safety and design features of nuclear power reactors. The aim of this study is to examine the effect of pure water and coolant containing Al2O3 nanoparticles on thermal performance of VVER-1000 nuclear reactor. In this study, the VVER-1000 reactor is in steady state and BOC (begining of cycle) condition, relative power density distributions for UO2 fuel with 3.7% enrichment were obtained with the MCNP code and then, thermal analysis were made with the COBRA code and DNBR value, which is very important for the safety criteria of the reactor, was examined. In addition, with the COBRA code, thermal values such as temperature, enthalpy, density, and temperature values of the fuel and clad regions, which are of great importance for the reactor, were calculated. As a result of the analysis, it was determined that the most efficient coolant is 0.1% Al2O3 fluid in the heat transfer of the reactor.

Karaduman Er, Irmak; Çorlu, Tugba; Yildirim, Memet Ali; Ates, Aytunc; Acar, Selim

In this study, the gas sensing properties of SnO2 and Zn0.50Sn0.50O samples produced by Succession Ionic Layer Adsorption and Reaction (SILAR) method with different SILAR cycles against NO gas were investigated. Electrical characterization of the produced sample at different temperatures (35 degrees C-135 degrees C) and different gas concentrations (50 ppb-25 ppm) were performed. The working temperature was found at 105 degrees C. The sensors were proved to have acceptable responses towards 50 ppb NO gas. Zn0.50Sn0.50O sensor exhibited improved sensing performance at working temperature of 105.C compared to SnO2 sensor.. The,responses of SnO2 sensors for the 50 ppb NO gas concentration, sensitivities of 1.74%, 2.15% and 3.37% were obtained for 20, 30 and 40 cycles, respectively. On the other hand, the,responses of Zn0.50Sn0.50O sensors for the 50 ppb NO gas concentration sensitivities of 3.01%, 3.74% and 4.16% were obtained for 20, 30 and 40 cycles, respectively. The measurement results showed that the sensitivity of the sensors changed depending on the doping and producing cycles.

Aslay, Semi Emrah; Bede, Tayfun

In this study, software is developed by using MATLAB codes, which can make building period calculation for a reinforced concrete structure with fast iteration technique. In this software, periods are obtained with the SAP2000 OAPI, depending on the individual extraction of each of the structural elements. According to the 2007 and 2018 Turkish Earthquake Regulations, building periods and building element extraction scenarios are comparatively rapidly iterated. As a result, repetitive structural analyzes, which will take very long time under normal conditions, are made in a very short time with the software created and all structural elements are evaluated on a period-by-term basis with the possibility of constituting a structural problem. With this aspect, the study provides a rapid solution in the field of civil engineering for creating damage scenarios and performing multi-dimensional analysis. At the same time, it contributes to the need to use computer automations in the evaluation of building elements.