In this work, the design features of delta wing vortex generators (DWVGs) on the thermo-hydraulic performance of heat exchangers are investigated using machine learning. Reynolds numbers, attack angle, length, wing-to-width ratio, and relative pitch ratio of DWVGs were used as descriptor variables, with Nusselt numbers, friction factors, and performance evaluation criterion (PEC) serving as target variables. Decision tree classification revealed the pathways leading to high or low values of the performance variables. Among many of those pathways, it was found that high Reynolds numbers (between 8160 and 9800) and high attack angles (greater than or equal to 47.5°) lead to high Nusselt numbers. On the other hand, an attack angle between 41° and 60°, a Reynolds number less than 8510, and a wing-to-width ratio greater than or equal to 0.4 causes a high friction factor. Finally, the PEC is likely to enhance when the Reynolds number is higher than or equal to 10,300 and the attack angle is between 47.5° and 60°. In addition to the decision tree analysis, SHapley Additive exPlanations (SHAP) analysis (a part of explainable machine learning) was also applied to reveal the importance of design features and their positive and negative effects on the target variables. For example, for a Nusselt number as the target variable, the Reynolds number was found to be the most influential variable, followed by the attack angle and the relative pitch ratio, all of which had a positive impact on the target. It was then concluded that machine learning methods could help provide strong insights into the configuration design features of heat exchangers in DWVGs to improve their efficiency and save energy.

The goal of this study is to model the global annual natural gas production using a variety of machine learning models in order to predict future production and determine a peak production date. World gross domestic product (GDP) based on purchasing power parities (at PPPs), inflation percentage, Henry Hub Price, Euro Price, cumulative natural gas resources, and annually discovered new resources were taken as descriptor variables, and Shapley analysis was conducted to observe the importance of features on the dataset. It was revealed according to this analysis that, Henry Hub price, inflation percentage, and newly discovered resources had minor effects on natural gas production, so they were left out. Then, a variety of machine learning algorithms were employed and the one with the highest prediction ability was found to be the stochastic gradient descent (SGD) algorithm. Next, this model was tested under four different scenarios, each with different GDP and natural gas price projections. Finally, natural gas production was found to reach its peak sometime between 2034 and 2046. It was then concluded that rather than relying on a traditional approach based on the Hubbert Curve, a machine learning model that takes into account all relevant factors can be used to accurately forecast natural gas production and its peak time, allowing governments and policymakers to make the necessary preparations.

The goal of this study is to use machine learning methodologies to identify the most influential variables and optimum conditions that maximize biochar, bio-oil, and biogas yields for slow pyrolysis. First, experimental results reported in 37 articles were compiled into a database. Then, an explainable machine learning approach, Shapley Additive exPlanations (SHAP), was employed to find the effects of descriptors on the targets, and it was found that higher biochar yields can be obtained at lower temperatures using biomass with low volatile matter and high ash content. Following that, decision tree classification was used to discover the variables leading to high levels of the targets, and the most generalizable path for high biogas yield was found to be where the maximum particle diameter was less than or equal to 6.5 mm and the temperature was greater than 912 K. Finally, association rule mining models were created to find associations of descriptors with very high levels of yields, and among many findings, it was discovered that biomass with larger particles cannot be converted into bio-oil efficiently. It was then concluded that machine learning methods can help to determine the best slow pyrolysis conditions for the production of renewable and sustainable biofuels.

In this review we tried to evaluate the differential diagnosis of leucocoria in patients with other causes than retinoblastoma in suspect of retinoblastoma and emphasize the findings that needs to be considered in differential diagnosis. We also tried to define the remarking findings in differential diagnosis of these lesions.

A 58-year-old otherwise healthy man received a diagnosis of choroidal malignant melanoma (CMM) in June 2021 and underwent a single session of (21 Gy) CyberKnife stereotactic radiotherapy (SRT). Eleven months later, we noticed 3+ anterior chamber cells with occasional vitreous cells in the left eye. Though the tumor looked regressed, there were mild optic disc leakage, early hypofluorescent and late hyperfluorescent punctate lesions scattered 360 degrees, and late staining of the mass on fluorescein angiogram. The findings were compatible with a unilateral multiple evanescent white dot syndrome (MEWDS)-like reaction that was most likely related to CyberKnife SRT-induced tumor necrosis, and a dexamethasone implant was administered intravitreally into the left eye together with topical steroids. A second intravitreal injection of dexamethasone was given three months later due to remittance of the angiographic features. As there are only a few reports on CyberKnife SRT for the treatment of CMM, we wanted to share our interesting observation of a post-treatment MEWDS-like reaction likely related to tumor necrosis syndrome with the ophthalmic community.

This study aims to reduce 1% of the annual emissions in the city of Izmir. In line with this target, this study worked on the integration of a liquid solvent-based DACS system within Izmir. Primarily, the emissions within the city boundaries were calculated based on the calculation method of each sector. For the mentioned target, each component’s energy requirement of the KOH solvent-based DACS system was calculated in detail. According to these calculations, the system’s total energy requirement, economic, and area calculations were obtained. As a result, the total emission amount was calculated as 11,809,362 tCO2. Total needed energy, area, and cost for DACS system resulted to be 1,169 kJ kg−1, 12,527 m2, and $136.6 million, respectively. In addition to numerical results, DACS is the most logical solution apart from increasing environmental awareness for creating a better, stronger, and environmentally friendly city for the near future.

A 16-year-old boy with X-linked retinoschisis was examined for the visual decline on his left eye. Upon examination, a vasopermeable elevated mass lesion was determined at the lower temporal retinal periphery associated with surrounding arc-like hard exudates which is consistent with a vasoactive proliferative tumor of the retina. After discussing the therapeutic options with the patient and his parents, 3 successive dexamethasone implants 6 months apart were administered. As no satisfactory regression was noticed, CyberKnife stereotactic radiosurgery (SRS) was performed. Regression of the exudative tumor was obtained in follow-up examinations at 12 and 24 months after the SRS session and the thickness of the lesion was markedly reduced.

Electricity is a critical utility for social growth. Accurate estimation of its consumption plays a vital role in economic development. A database that included past electricity consumption data from all OECD countries was prepared. Since national trends may be transferable from one country to another, the entire database was modeled and simulated via machine learning techniques to forecast the energy consumption of each country. Understanding similarities among the profiles of different countries could increase predictive accuracy and improve associated public policies.

An electric arc furnace with a liquid steel capacity of 30 t was analyzed using the second law of thermodynamics. To carry out the exergy analysis, materials and energies entering and exiting the electric arc furnace were determined. The materials included several types of scrap, cokes, fluxes, oxygen, liquid steel, stack gases, and dust. Electrical and exothermic chemical energies of these materials were considered. Energies of the materials leaving the furnace, including liquid steel, slag, stack gases, and dust, were determined, as were the chemical reactions and exergies entering and leaving the electric arc furnace. Exergy efficiency and lost exergy were calculated. It was found that 42.6% of exergy is lost because of the chemical reactions, heat transfer, and other reasons. The overall exergy efficiency of the entire system was found to be 46%.

Amaç: Bu çalışmanın amacı Down sendromu veya herhangi bir kromozomal-genetik anomalisi olmayan zihinsel engelli pediatrik hastalarda oküler patolojilerin araştırılmasıdır. Gereç ve Yöntemler: Bu çalışmaya 2010 ve 2011 yılları arasında 79 zeka geriliği olan ve 110 sağlıklı çocuk olmak üzere toplam 189 hasta dahil edildi. Hastaların demografik faktörleri (yaş, cinsiyet) ile etkilenen taraf, görme keskinliği, ezotropya, ekzotropya, ön segment patolojileri ve arka segment patolojileri değerlendirildi. Çalışma grubundaki tüm pediatrik hastalar Wechsler Çocuklar için Zeka Ölçeği-Yenilenmiş Formu’na göre IQ düzeyi 70 olarak ayrıldı. Bulgular: Zeka geriliği olan çocukların yaş ortalaması 11,85±6,19 (3-17) yıl iken sağlıklı çocukların yaş ortalaması 10,73±3,35 (3-15) yıl idi. Görmesi değerlendirilen 74 hastanın 8'inde görme bozukluğu varken, sağlıklı grupta ise hiç görme bozukluğu yoktu (sağ ve sol için sırasıyla p=0,001 ve p=0,004). Düşük IQ'lu çocuklarda, 2 (%2,5) olguda ön segment patolojisi ve 3 (%3,8) olguda ise arka segment patolojisi saptandı. Düşük IQ'lu hastaların 7 (%8,9)'sinde şaşılık saptanırken sağlıklı çocuklarda ise hiç şaşılık saptanmadı. Zeka geriliği olan olguların 5 (%6,3)'inde ekzotropya, 2 (%2,5)'sinde ise ezotropya vardı. Ekzotropya zeka geriliği olan çocuklarda kontrol grubuna göre anlamlı derecede daha yüksek olarak bulundu (p=0,012). Sonuç: Zihinsel engelli çocuklarda görme bozukluğu, ön-arka segment patolojisi, ekzotropya yüksek prevalansa sahipti ve tüm oküler patolojiler düşük zihinsel engelle ilişkiliydi.

Aim: The aim of this study is to investigate the ocular pathologies in mentally retarded pediatric patients without Down syndrome or any certain chromosomal-genetic anomaly. Material and Methods: A total of 189 patients, including 79 mental retarded and 110 healthy children, were included in this study between 2010 and 2011. Demographic factors (age, gender) of the patients, and affected side, visual acuity, esotropia, exotropia, anterior segment pathologies and posterior segment pathologies were evaluated. All pediatric patients in study group were divided as IQ level 70 according to Wechsler Intelligence Scale for Children-Revised Form. Results: The mean age of the children with mental retardation was 11.85±6.19 (3-17) years, while the mean age of healthy children was 10.73±3.35 (3-15) years. While visual impairment was present in 8 of the 74 patients whose vision was evaluated, there was no impairment in the healthy group (p=0.001 and p=0.004 for right and left, respectively). Anterior segment pathology was detected in 2 (2.5%) cases, and posterior segment pathology in 3 (3.8%) cases in children with low IQ. While strabismus was detected in 7 (8.9%) patients with low IQ, no strabismus was found in healthy children. Five (6.3%) of the cases with mental retardation had exotropia and 2 (2.5%) had esotropia. Exotropia was found significantly higher in children with mental retardation compared to the control group (p=0.012). Conclusion: Visual impairment, anterior-posterior segment pathology, exotropia had a high prevalence in children with mental retardation, and all ocular pathologies were related to low intellectual disability.

In this work, ultrafast thermalization dynamics was examined for a variety of two layer-thin films (Au/Si, Au/Ni, Au/W, Au/Al and Au/Pb). Non-equilibrium energy transport under laser irradiation was formulated for the electron and lattice sub-systems of the thin films. A significant reduction in the temperature of the electron and the lattice of the gold surface was observed especially for Au/Si and Au/Ni thin films due to their large G values. Next, the effects of laser power intensity and laser heating duration on the temperature distributions were examined for Au/Ni two-layer thin film. It was found that, as the laser intensity increased, the maximum electron temperature increased dramatically; on the other hand, as the pulse heating duration increased, the electron temperature gradually decreased. It was then concluded that thermal damage threshold of the gold surface can be improved by depositing gold layer on a substrate material with high electron-phonon coupling factor. Hence the thermal failure of thin films used in optical components of ultrafast laser systems or micro/nano electro mechanical systems can be prevented.

Natural gas is a foreign-dependent source of energy in many countries and a rapid increase of its consumption is mainly associated with the increase of living standards and needs. In this work, Turkey was taken as a case study with high degree of foreign dependence of energy, and the future natural gas consumption was predicted by several different multiple regression models using socio-economic indicators as the descriptor variables. Among these, gross domestic product and inflation rate were found to be the only significant ones for this prediction. Next, three different projections for the future values of the significant descriptor variables were tested, and the natural gas consumption was predicted to rise gradually in the range 1.3 +/- 0.2 billion m(3) per year reaching to a consumption of 64.0 +/- 3.5 billion m(3) in the year 2025. It was then discussed that this additional natural gas can be compensated by utilizing local lignite sources or by starting a nuclear energy program although these two methods to reduce the future natural gas consumption have some conflictions with the general European energy matrix and environmental politics. Thus, it was concluded that resuming the wind and solar-based electricity generation programs can be considered as a more reasonable option. (C) 2019 Elsevier Ltd. All rights reserved.

A theoretical post-dryout heat transfer model is developed for two-phase dispersed flow, one-dimensional vertical pipe in a post-CHF regime. Because of the presence of average droplet diameter lower bound in a two-phase sparse flow. Droplet diameter is also calculated. Obtained results are compared with experimental values. Experimental data is used two-phase flow steam-water in VVER-1200, reactor coolant system, reactor operating pressure is 16.2 MPa. On heater rod surface, dryout was detected as a result of jumping increase of the heater rod surface temperature. Results obtained display lower droplet dimensions than the experimentally obtained values.

In this work, several simulations and analyses are carried out to investigate the feasibility of generating electricity from sea underwater currents at Istanbul Bosphorus Strait. Bosphorus is a natural canal which forms a border between Europe and Asia by connecting Black Sea and Marmara Sea. The differences in elevation and salinity ratios between these two seas cause strong underwater currents. Depending on the morphology of the canal the speed of the flow varies and at some specific locations the energy intensity reaches to sufficient levels where electricity generation by marine current turbines becomes economically feasible. In this study, several simulations are performed for a 10 MW marine turbine farm/ cluster whose location is selected by taking into account several factors such as the canal morphology, current speed and passage of vessels. 360 different simulations are performed for 15 different virtual sea states (for 5 significant wave heights and 3 peak periods). Similarly, 8 different configurations are analyzed in order to find the optimum spacing between the turbines. Considering that the complicated morphology of the strait may cause some spatial variations in the current speed within the selected region, the analyses are performed for three different flow speeds corresponding to 10 % increase and decrease in the average value. For each simulation the annual energy yield and cluster efficiency are calculated.

Solar hot water and space heating systems have been an important energy conservation technique in buildings, along with improving insulation efficiency of building envelopes and HVAC systems. According to statistical data from EU, installations of solar hot water heating systems are increasing progressively. The purpose of this study is to illustrate quantitatively the feasibility of optimal space and water heating system using solar energy. The house is assumed to be located in Cesme, Turkey, where 1304 kWh/m 2 -year of solar radiation for the period of 2734 h/year is measured. Considering the space heating and hot water demand in this geographic location, solar collector and storage capacity are optimized using f -Chart method. The results showed that a 92% of the total energy demand can be covered by solar energy.

Solar hot water and space heating systems have been an important energy conservation technique in buildings, along with improving insulation efficiency of building envelopes and HVAC systems. According to statistical data from EU, installations of solar hot water heating systems are increasing progressively. The purpose of this study is to illustrate quantitatively the feasibility of optimal space and water heating system using solar energy. The house is assumed to be located in Cesme, Turkey, where 1304 kWh/m 2 -year of solar radiation for the period of 2734 h/year is measured. Considering the space heating and hot water demand in this geographic location, solar collector and storage capacity are optimized using f -Chart method. The results showed that a 92% of the total energy demand can be covered by solar energy.

Giriş: Bu araştırmanın amacı; Ankara Üniversitesi Diş Hekimliği Fakültesi Hastanesi örneğinde, ortodonti bölümü hastalarının tedavi öncesi durumluk kaygı düzeylerini belirleyerek, bunu etkileyen faktörleri ve çözüm önerilerini ortaya koymaktır. Gereç ve Yöntem: Katılımın gönüllülük esasına göre belirlendiği araştırmada, 118 ortodonti hastasına anket formları dağıtılmıştır. Dağıtılan anket formlarının tamamı geri dönmüş ve analize dahil edilmiştir. Hastalar demografik özelliklerine göre gruplara ayrılarak, grupların durumluk kaygı düzeyleri arasındaki farklılıklar araştırılmıştır. Durumluk kaygı düzeyinin ölçümü için Spielberger Durumluk ve Sürekli Kaygı Envanteri’nin STAI , ‘Durumluk Kaygı Alt Ölçeği STAI-S ’ kullanılmıştır. Bulgular: Katılımcı hastaların tedavi öncesi durumluk kaygı düzeyi ortalama 39.5 olarak bulunmuştur Ort.= 39.466, SD=11.598 . Bu düzey, durumluk kaygı için kesim noktası değeri düzeyindedir. Buna ilave olarak çalışmamızda medeni durum, meslek, gelir durumu, yaş, eğitim durumu ve diş hekimine gidiş sıklığı değişkenlerine göre gruplandırılan hastaların durumluk kaygı düzeyleri arasında anlamlı farklılıklar saptanmıştır

This work is concerned with the optimization of use of tailwater energy at hydropower plants. As a case study, extensive analyses are performed to determine the main features of the array of low-head turbines that are planned to be installed at the tailwater of the two main generators of Sanibey Dam. Sanibey Hydropower Plant is constructed on Seyhan River at Aladag region, Adana, Turkey. The plant has currently two Francis turbines (158.5 MW of each) with a total capacity of 317 MW. Tailwater can be briefly defined as the water leaving the main generators of the hydropower plant. Although most of its energy is converted to mechanical energy by rotating the blades of the turbine, it has still some energy which can be exploited by using low head run-of-river type turbines. Design and optimization of these secondary systems are nowadays among the popular research topics. This work investigates the feasibility of developing such a hydro-matrix structure consisting of an array of low-head small size turbines. Several analyses are performed to determine the optimum number and technical specifications of the generators. In this work, two different approaches aiming at maximizing the power output or minimizing the investment return period are utilized in the optimizations. Two year outflow statistics and hourly data of several operational parameters of the existing Francis turbines (provided by the operators of the dam) are analyzed to maximize the power output. Similarly, energy markets hourly price data is used for calculating the corresponding payback period and to minimize the return time of the investment. The results of the analyses obtained by using different design objectives are quite similar. The approach aiming at minimizing the payback period yields the optimal number of turbines as 27. The return time and the cost of the investment are 8.13 years and 4,940,310 USD, respectively. In power maximizing approach, the optimum number of turbines is calculated as 30. The return time and the cost of the investment are 8.15 years and 5,490,978 USD, respectively. The re-use of expensive raw material (water in this case) also results in approximately 6 % increase in the overall efficiency of the hydropower plant.

This paper is an attempt to demonstrate the effect of sea water temperature on the overall efficiency of electric power generation combined with a water desalination plant. The plant under consideration is composed of two thermally and mechanically coupled loops: a steam power plant loop to produce electricity and a reverse osmosis loop including pressure exchange system to provide drinkable water from seawater. The reverse osmosis loop including pressure exchange system is known to be the state of the art desalination technology for obtaining fresh water. The waste pressure from reverse osmosis is transferred to the low pressure concentrate in a pressure exchange system to save a considerable amount of energy. It is shown in the body of paper that the sea water inlet temperature has a direct impact on the overall efficiency of the system. This is fundamentally accomplished by the rejected heat of Rankine cycle in a condenser. As a result, this paper shows that the overall efficiency of the combined plant is found to be highest when sea water temperature at the condenser exit is elevated to around 30 degrees C.