Mehmet Ali Kallioğlu

Bu çalışmada, n-bütanol katkılı dizel karışımlarında Al₂O₃ nanoparçacık konsantrasyonunun etkileri yanıt yüzey metodolojisi (YYM) ile sistematik olarak incelenmiş ve optimize edilmiştir. Deneyler, motorun dört farklı yük koşulunda (0.3; 1.0; 2.0 ve 3.0 FOEB) ve nanoparçacık konsantrasyonlarında (0, 25, 50, 75 ve 100 ppm) gerçekleştirilmiştir. YYM’ye dayalı merkezi kompozit tasarım (MKT) kullanılarak istatistiksel deney tasarımı (DoE) uygulanmış ve performans ile emisyon çıktılarının optimizasyonu yapılmıştır. Sonuçlar, 75 ppm seviyesinde fren efektif veriminde (FEV) %18.75 artış ve fren özgül yakıt tüketiminde (FÖYT) %20.75 iyileşme sağlandığını göstermiştir. Ayrıca CO, HC ve duman emisyonlarında belirgin azalmalar elde edilirken, yüksek oksijen içeriği ve silindir içi sıcaklık nedeniyle NOₓ emisyonlarında artış gözlenmiştir. YYM analizleri, optimum nanoparçacık konsantrasyonunun dengeli koşullarda 85 ppm, performans odaklı durumda 80 ppm ve emisyon odaklı durumda 91 ppm olduğunu ortaya koymuştur. Bulgular, Al₂O₃ katkılı nanoyakıtların sürdürülebilir dizel motor uygulamaları için güçlü bir potansiyel sunduğunu göstermektedir.

The importance of solar radiation for the body’s ability to synthesize Vitamin D₃ is well documented, yet the precise amount of sun exposure required to avoid Vitamin D insufficiency is less clear. To address this knowledge gap, this study sought to utilize the sun in a suitable period at the optimum dose by utilizing numerical simulations to determine the amount of Vitamin D₃ synthesis in the skin according to season, time of day, and geographical location in Turkey. The study was carried out in three stages; in the first stage, daily, monthly, and annual values were determined in cases where the solar zenith angle has the active UV-B wavelength. The second stage determined the level of Vitamin D that can be synthesized in all skin types at 25% solar radiation exposure. In the third stage, the sun exposure time required for 1000 International Units (IU) for all skin types was calculated. According to the analysis, the yearly period of active synthesis of D₃ on Earth lasts from the beginning of March to the third week of October. During the day, it is between 10:00 and 16:00. For 1000 IU/day, the average annual estimated times (minutes) are 5.05 for Type I, 6.3 for Type II, 7.6 for Type III, 11.35 for Type IV, 15.15 for Type V, and 25.25 for Type VI. The results of this paper will impact awareness for academic-medical users.

Energy efficiency is at the top of the measures created against the ever-increasing energy need for supply. Moreover, the global climate crisis, the protection of the environment, and the improvement of the economy are only possible by optimizing active energy systems. For this purpose, it is a requirement that the solar panels have the appropriate tilt angles and correct positions in order to maximize the efficiency of solar energy systems. In this study, for the province of Van (43°38’ N-38°50’ E), whose solar energy potential is higher than the average of Turkey, the optimum solar panel angle according to the months of the year was determined for the south-facing solar panels. It has been determined that the annual panel inclination angle is 30.540 and in the case of monthly change of panel angles, the annual yield increases up to 14% compared to the horizontal plane, reaching an average annual radiation value of 5090 Wh/m2-day. 8 different mathematical models have been developed from 4 different variables for estimating the optimum angle value specific to the latitude of the region. The statistical coefficient of certainty (R2) range of these models varies between 0.9068 and 0.9964. As a result of these findings, the regression model, whose applicability and reliability have been proven, can serve as examples of locations at different coordinates in the same latitude. Furthermore, the results set an example for academics and industrialists in terms of the proposed model's engineering design, eco-energy analysis, and use in optimal design processes.

This study empirically examines the effectiveness of the solar chimney power plants (SCPP), which is an innovative method for the use of solar energy, in the middle latitude region (37.88° N) in the northern hemisphere. Experimental measurement parameters of temperature, velocity, and radiation obtained from four cardinal directions (north, south, east, and west) and from 26 different locations were recorded throughout the day (08:00 am-07:30 pm). These measurements were used to calculate and estimate the power values used to measure the energy efficiency of the solar chimney. In the study, the genetic programming method was used to estimate the power value. In the five different forecast models developed, 15 different parameters were used diagonally. The obtained power estimation equations were cross-checked using statistical methods. Determination coefficient value is higher than >0.90 in all equations and is close to the ideal. In the comparison of all statistical models, the Global Performance Indicator (GPI) was used, with the best result obtained from Model 2. The results of this model are MAPE:6.5233, MBE: −0.0124, RMSE:1.1036 ve t-stat:0.0374, which is quite close to zero. In addition, the power values obtained from both the calculated and developed models were dimensioned and compared over the power-time factor of eight different studies in the literature. The mean relative error value nof the values calculated as a result of this comparison varies between 2.3% and 21.3%. This study provides a model for the different geometries of solar chimney prototypes and provides an example for measuring the design and performance of solar chimney systems to be installed in the middle latitudes and in regions with “Csa” climate characteristics, and is recommended for academic and industrial users. The mathematical models developed can be considered as a step to increase the efficiency of the solar chimney power plants.

The current study depicts the effects of different insulation materials and fuel types on the cooling and heating performance of buildings situated in hot and dry, warm and humid, composite, and cold climatic conditions in India. Ten different locations chosen from diverse climatic regions were selected, and various potential parameters for expanded polystyrene and extruded polystyrene insulation materials were evaluated. Potential parameters, such as optimal insulation thickness, annual savings, and payback period, were computed for cooling and heating requirements and were found in the ranges of 0.0428–0.891 m, 10.83–19.19 $/m², and 1.49–2.36 years for cooling, as well as 0.0063–0.1522 m, 0.29–55.92 $/m², and 0.95–6.52 years for heating, respectively. An emission analysis was also carried out for the estimation of greenhouse gas (GHG) emissions by the engagement of optimal insulation thickness for heating. The GHG emissions from natural gas, coal, and diesel by the employment of various insulating materials were found in the ranges of 5.39–11.28, 9.47–32.68, and 2.26–4.51 kg/m²-year, respectively. A correlation formulation (power) for optimal insulation thickness was also carried out. For checking the preciseness of the developed mathematical models, statistical tools were utilized, and their obtained values in the satisfactory range signified the accurateness of the developed models.