• Energy Research
• 2021-2025close
• TR close

Abstract Based on the design concept of a fourth-generation smart pipe network system, this paper innovatively proposes a new TOTS (Two-supply/One-return, triple pipe structure) arrangement method for district heating systems. Moreover, to accurately predict the heat loss due to the pipeline operation of the multi-pipe system, based on the multipole calculation method, a new heat loss theoretical analytical model for the TOTS was created; additionally, a corresponding three-dimensional numerical simulation model was established, which was analyzed and numerically solved. The results showed that in comparison with thermal loss data measured by Danfoss et al., the above analytical and numerical models have a high accuracy, and the deviation is within 2%. Additionally, through calculations, it was found that the distance between the heating pipes is an important factor that affects the total heat loss from the new multi-control heating system and the actual heat exchange between pipes.

Today, data accumulated during internet use have become an important source of information for people’s behaviour, issues, and needs, and due to real-time data acquisition, Google search data have become a focal point for researchers. As a result, it has been become more common to use GT data, which have been included in forecasting models for many economic indicators, including unemployment rate forecasting. Therefore, this study aims to determine whether including Google search data in forecasting models can improve the model’s performance in forecasting the unemployment rate in Turkey. In this context, out-ofsample forecasting was performed in this study using seasonally adjusted monthly unemployment rates for the period between January 2005 and August 2020 and monthly GT data about the topic of unemployment insurance. In addition, the forecasting performance of ARIMA and ARIMAX methods were compared.

Undoubtedly, the transition to electromobility with several million new, efficient charging points will have consequences for the energy industry, and in particular for network operators of the distribution infrastructure. At the same time, in the coming years the energy landscape will change into a system in which an increase in decentralized systems based on renewable energy sources will take over the leading function. This transformation process will further increase the complexity and overall pressure for change in energy systems over the next decade. In order to be able to ensure the energy supply and the reliable system operation of the grids in the future as well, communicative networking of generators, storage systems, electrical consumers and grid equipment is indispensable. This study aims to investigate the consequences of including electric vehicles in Istanbul’s power system using a unit commitment simulation model. The presented considerations analyze how uncertain and managed charging strategies affect the power system in terms of operating costs and renewable resources. The presented simulations indicate that, in economic terms, the use of a managed charging strategy saves 2.3%, reducing the total cost from USD 66.71 million to USD 65.18 million. The recipients of the presented research are both the demand and supply sides of the future energy transformation based on the idea of synergy of electromobility and renewable energy sources within the framework of the smart city idea.

This paper presents the experimental and numerical studies of the vertical stress distribution beneath the centerline of circular footings resting on the sand. Vertical stress values due to circular load in medium-dense sand were measured using soil stress transducers. Reduced-scale laboratory model tests were carried out in a square-shaped test box and vertical stresses were measured at the centerline of the circular footing at different depths of the sand. In order to determine the effect of footing width on vertical stress distribution, laboratory experiments were performed on circular footings of different diameters. In addition, a series of finite element analyses was carried out on the test model to validate the findings of the experimental study. In the numerical analysis, the sand was modeled as a non-linear elastoplastic material. The analyses were performed using the finite element method with two-dimensional axisymmetric and three-dimensional conditions. The results obtained from laboratory model tests and numerical analysis were compared with the vertical stress values obtained from the theoretical solution in the literature. Vertical stress distribution in horizontal planes at any depth from the footing base shows the same characteristic form in all methods. However, some differences were observed between experimental, numerical, and theoretical results and discussed.

Edebi eserler; kurgu, olay örgüsü, kahramanlar ve mekân gibi unsurların yanında dilin kullanımı ve dilin özelliklerini yansıtması bakımından eğitim açısından önemli materyaller olarak kabul edilmektedir. Edebiyatın yabancı dil öğretimiyle ilişkisi ve edebiyatın yabancı dil öğretiminde kullanımı, birçok çalışmada ele alınmış olmasına rağmen, karşılaştırmalı edebiyat ile yabancı dil öğretimine ilişkin çalışmalar Türkiye’de sınırlı sayıda bulunmaktadır. Bu bağlamda bu çalışmanın amacı karşılaştırmalı edebiyatın yabancı dil öğretiminde kullanımının dil öğretim ve öğrenim sürecine etkilerini incelemektir. Bu amaca ulaşmak için Alman edebiyatında önemli bir yeri olan Prag’da yaşamış Franz Kafka’nın ve Türkiye’de doğup büyümüş Türk edebiyatına farklı bir soluk getiren Oğuz Atay’ın eserleri, yabancı dil derslerinin öğretim durumlarının tasarlanmasında kullanımına örnek olarak incelenmiştir. Farklı topraklarda ve dönemlerde, farklı tarihsel, siyasal, sosyolojik ve kültürel yapılarda yaşayan iki yazarın eserlerindeki farklılıklar ve benzerliklerin dil öğretiminde nasıl kullanılabileceği örneklendirilmiştir. Çalışmada karşılaştırmalı edebiyatın yabancı dil öğretiminde kullanılmasının kelimelerin derin anlamlarının kavranması, kelimelerin bilinen anlamlarının dışında farklı anlamlarda kullanılabileceği, günlük dil kullanımlarından farklı ifade biçimlerinin görülmesi, edebi dilin kullanılabilmesi ve anlama gibi dil becerilerinin öğretimine katkı sağlayabileceği sonucuna ulaşılmıştır.

The most commonplace natural flow inside one-ended inclined pipes today is water heating systems. In this study, a model was created for the estimation of the pipe outlet temperature of the fluid with the energy balance for the inside of the tank, flow rate calculation of natural circulation, and other thermal calculations in a one-ended inclined pipe. In addition, this model has been compared with the Li model in the literature, and it is easier and more successful. 100 W, 200 W, 400 W, 600 W, and 800 W thermal power was applied to a one-ended inclined pipe, and the temperature values were recorded in five minute periods in the experiments that lasted a total of six hours. As the average of the experiments, the estimation results for the current model and the Li model are: the average per-cent relative error rates are 6.02 and 15.1 and the coefficient of determination, R2, are 0.9865 and 0.9683, respectively.

This study tests binary and ternary n-pentanol, ethanol, and petrol blends to increase spark-ignition (SI) engine performance and minimize CO and HC emissions. To improve brake thermal efficiency (BTE) and reduce emissions, adding ethanol into gasoline is one of the practices used in Automobiles. But the literature reported some performance limitations and problems with adding a high ethanol concentration to gasoline as phase separation problem occurs in fuel tank due to the hygroscopic nature of ethanol, a higher ethanol concentration may corrode some parts of the fuel supply system. Ethanol has a lower calorific value than gasoline, so a higher ethanol concentration in blends beyond a specific limit reduces BTE. N-pentanol as a fuel additive in gasoline can better solve these problems due to its high caloric value compared to ethanol. Also, when n-pentanol is mixed with gasoline and exposed to moisture, it does not separate in stages as in the ethanol case. Accordingly, this research aims to evaluate n-pentanol's viability as a fuel additive in petrol and ethanol-gasoline blends at different compression ratios. The experiments were carried out on a single-cylinder, four-stroke spark-ignition engine running at a constant speed. Different blends of n-pentanol with gasoline and ethanol were tested, and results were compared against gasoline and E10 (the optimal blend of ethanol-gasoline, 10/90 v/v %). Various parameters were examined, including BTE, brake-specific fuel consumption (BSFC), and different exhaust pollutants. The effects of compression ratio values on these parameters were also recorded. The 1.5 vol% pentanol with E10 (E10P1.5) mix has the best overall characteristics, including low BSFC, high BTE, and low CO and HC emissions compared to petrol and E10 fuels. E10P1.5 shows a maximum enhancement in BTE, low BSFC, CO reduction, and HC reduction by 23.79%, 19.80%, 37.79%, and 19.46%, respectively, over gasoline. Compared to E10, the improvement is 3.64% for BTE, 4.59% for BSFC, 8.88% for CO emission reduction, and 4.13% for HC emission reduction.

Bu çalışmada dar gövdeli Boeing 737 NG ve Airbus A 319 dar gövdeli ve Boeing 777-200 ve Airbus A330-300 geniş gövdeli uçaklarının karşılaştırmalı etkinlik analizlerinin örnek veriler üzerinden finansal ve operasyonel göstergeler kullanılarak yapılması amaçlanmaktadır. Bu çalışmada TOPSİS yöntemi kullanılarak yapılan analitik çalışmada kullanılan veriler esas alındığında; bölgesel uçuşların gerçekleştirdiği dar gövdeli uçaklardan B737-700’ün, A319’a göre; uzun mesafeli ve kıtalararası uçuşların gerçekleştirildiği geniş gövdeli uçaklardan A330-330 uçağının, B777-200 uçağına göre maliyet avantajına sahip olduğu belirlenmiştir. Çalışmada ayrıca kullanılan radar grafik yöntemine göre; A319 dar gövdeli uçağının B 737-700 dar gövdeli uçağına göre genel olarak daha üstün operasyonel özellikler gösterdiği; B 777-700 geniş gövdeli uçağının ise A330 geniş gövdeli uçağına göre genel olarak daha üstün operasyonel özellikler gösterdikleri belirlenmiştir