Yazarlar
- Cuce, Erdem(27)
- Cuce, Pinar Mert(22)
- Tozlu, Alperen(12)
- Guclu, Tamer(10)
- Karaali, Rabi(10)
- Imamoglu, Ilyas Kays(7)
- Isik, Cem(7)
- Ongan, Serdar(7)
- Aydin, Rahman(4)
- Hırca, Tuğçe(4)
- Karaali, R.(4)
- Keven, Arzu(4)
- Özahi, Emrah(4)
- Abusoglu, Aysegul(3)
- Ceviz, Mehmet Akif(3)
- Eryılmaz Türkkan, Gökçen(3)
- Kuziboev, Bekhzod(3)
- Serencam, Uğur(3)
- Tozlu, A.(3)
- Yıldırım, Ümit(3)
- Çakir, Uǧur(3)
- Çomakli, Kemal(3)
- Abuşoǧlu, A.(2)
- Afshari, Faraz(2)
- Aloui, F(2)
- Arslantürk, Cihat(2)
- Atabani, A.E.(2)
- Ayşegül, Çokgez Kuş(2)
- Dincer, I(2)
- Erol, Şahin(2)
- Guleryuz, Didem(2)
- Güler, Cüneyt(2)
- Güngör, Osman(2)
- Jomaa, Seifeddine(2)
- Kamiloğlu, Hakan Alper(2)
- Kemal, Çomakli(2)
- Köksal, Hüseyin(2)
- Niazkar, Majid(2)
- Ozahi, Emrah(2)
- Riffat, Saffa(2)
Yayınlar
- MakaleAçık Erişim2024Scopus SJRQ3Durability of slag-based alkali-activated materials: A critical review
Gökçe, H.S.
As the world becomes increasingly aware of the devastating effects of climate change, the need for sustainable building materials that are both durable and environmentally friendly increases. Geopolymer and alkali-activated materials formed by a chemical reaction between an alkaline activator solution and an aluminosilicate source have gained popularity in recent years. The alkaline activator solution dissolves the aluminosilicate source, which then undergoes a polycondensation reaction to form a three-dimensional geopolymeric gel network. The development of this network ensures the strength and durability of the material. Today, this phenomenon of durability has been studied in detail to enable the development of superior construction materials, taking into account degradation mechanisms such as carbonation, leaching, shrinkage, fire, freezing and thawing, and exposure to aggressive environments (chlorides, acids, and sulphates). Although there are many unsolved problems in their engineering applications, slag-based alkali-activated materials appear to be more advantageous and are promising as alternative materials to ordinary Portland cement. First of all, it should not be ignored that the cure sensitivity is high in these systems due to compressive strength losses of up to 69%. Loss of strength of alkali-activated materials is considered an important indicator of degradation. In binary precursors, the presence of fly ash in slag can result in an improvement of over 10% in compressive strength of the binary-based alkali-activated materials after undergoing carbonation. The binary systems can provide superior resistance to many degradation mechanisms, especially exposure to high-temperature. The partial presence of class F fly ash in the slag-based precursor can overcome the poor ability of alkali-activated materials to withstand high temperatures. Due to the desired pore structure, alkali-activated materials may not be damaged even after 300 freeze–thaw cycles. Their superior permeability compared to cementitious counterparts can extend service life against chloride corrosion by more than 20 times. While traditional (ordinary Portland cement-based) concrete remains the most widely used material in construction, geopolymer concrete’s superior performance makes it an increasingly emerging option for sustainable and long-lasting infrastructure.
AtıfScopus69WoS63OpenAlex70
İncele - MakaleYalnız künye2024Scopus SJRQ2Optimization, Characterization, and Carbon Footprint Analysis of Alkali Activated Waste Tuff and Fly Ash Mixtures for Deep Mixed Columns
Kamiloğlu, Hakan Alper; Yilmaz, Fatih
Deep soil mixing (DSM) applications are one of the widely known soil stabilization techniques which can be applied to a wide range of soil types. Cement and lime are the major materials used as binders for DSM applications. However, as conventional binders lead to emit a large amount of CO2 during production, eco-friendly binders suitable for DSM applications have become prominent. Alkali-activated materials are good alternatives to conventional binders. This study was intended to investigate the usability of zeolite rich tuff wastes as an alkali-activated binder in DSM columns. Within this scope, the waste tuff and C-type fly ash mixture were used as an alkali-activated binder, and 10 M NaOH solution was used as an activator. Response surface methodology (RSM) was employed in experimental design to determine optimum components to obtain maximum unconfined compression strength and investigate the interaction between stabilization agents. From the RSM analysis the optimum ratios of activator (X1), waste tuff (X2), and precursor (X3) were determined as; X1 = 0.251, X2 = 0.548, and X3 = 0.538 for maximum UCS. UCS, mineralogical and microstructural characterization (XRF, XRD, SEM, EDX, FTIR) was performed for the DSM samples prepared considering the optimized components. It was determined that the UCS values of the 3, 7, and 28-day cured samples stabilized by considering the optimum values gave UCS values approximately 3 to 5 times higher than the lower limit values recommended by FHWA. As a result of mineralogical and microstructural investigation, the reason for the strength increase in the samples can be attributed to the formation of geopolymeric gel between the soil particles by tuff waste and fly ash activated with alkaline activator. Carbon footprint analyses were performed for 1m3 DSM columns produced with alkali-activated binders and ordinary Portland cement (OPC). From the analyses it was seen that the carbon footprint of the DSM column produced using alkali activated binders is lower than that of the DSM column obtained with OPC. After the general evaluation of the study, it is seen that the hypothesis that waste tuff can be used as environmentally safe alkali-activated binders instead of traditional binders is supported.
AtıfScopus6OpenAlex6İncele - Kitap BölümüAçık Erişim2024Are Organic Foods Better for the Environment? Comparison of Environmental Costs of Organic and Conventional Foods
Alkaya, Fatime; Günay, Esra; Turna, Hilal
Biodiversity loss, soil and water pollution as well as global warming are among the most debated environmental issues worldwide. Conventional farming, which uses chemical pesticides and fertilizers, hormones and genetically modified products to obtain maximum yield per unit of land to feed the rapidly growing world population, is one of the main causes of these problems. As an alternative production system to conventional farming, organic farming has emerged to overcome environmental problems. The effectiveness of organic farming in addressing environmental issues has been debated for many years. In this chapter, the impact of organic foods on the environment is evaluated under the headings of biodiversity, soil and water quality, energy efficiency and climate change. The consensus drawn from studies is that organic farming is a more environmentally friendly production method compared to conventional farming. However, the heterogeneity of studies and environmental factors are influenced by many factors, making it difficult to reach a consensus.
- MakaleAçık Erişim2024Scopus SJRQ3Thermoeconomic Analyses of Heat Pumps
Öztekin, Erman Kadir; Gür, Mehmet Murat; Karaali, Rabi
Recently, the rapid development of technology and the increase in energy costs and needs have made reducing the costs and efficient use of energy and exergy important. The thermoeconomic analysis method, which is the best cost analysis method of energy and exergy, gives the ways to reduce costs and increase efficiency that can be applied a facility. It has been found that the most suitable thermoeconomic solution for winter heating and summer cooling of a facility is a vertical underground source heat pump and the most high-performance working fluid that should be used is R32. If the heating is done with a ground source heat pump instead of electrical energy, 4.25 kW of heating energy will be obtained for each kW of electrical energy given for heating, since the costs are COPIP 4.25. Here the earnings increase by around 325%. In other words, heating costs decrease by around 77.5 percent, that is, from one hundred liras to 22. 5 liras.
AtıfOpenAlex4İncele - MakaleYalnız künye2024Scopus SJRQ1Design, modelling, environmental, economic and performance analysis of parabolic trough solar collector (PTC) based cogeneration systems assisted by thermoelectric generators (TEGs)
Cuce, Pinar Mert; Guclu, Tamer; Cuce, Erdem
Concentrating solar power systems (CSP) is a very efficient technology for clean and renewable energy production. It basically works on the principle of focusing the sun's rays with the help of a reflective surface. There are two types of CSP systems: point-focused and line-focused. Point-focused ones are parabolic dish collectors and solar towers. Line-focused ones are parabolic trough collectors (PTCs) and linear Fresnel reflectors. It is possible to reach focus temperatures over 1000 °C with point-focused CSPs. Line-focused CSP systems are used to obtain thermal and electrical energy at temperatures below 500 °C. Among CSP technologies, PTCs are widely preferred. While it can be used alone, it can also be used in combination with other power generation systems by creating hybrid systems. In this regard, hybrid PTC/TEG energy systems created with thermoelectric generators (TEGs) come to the fore. These systems have higher electrical and thermal efficiency values compared to traditional PTCs. In this study, CSP systems, PTCs, TEGs and hybrid solar energy systems-based PTCs were examined in detail. It is concluded from the study that the total thermal efficiency of PTC-TEG hybrid systems can be enhanced by up to %70 with respect to PTC systems.
AtıfScopus42WoS40OpenAlex37İncele - MakaleYayıncıda açık erişim2024Scopus SJRQ1Energy, exergy, environmental, and enviroeconomic (4E) analysis of cascade vapor compression refrigeration systems using nanorefrigerants
Yılmaz, Metin; Cimşit, Canan; Keven, Arzu; Karaali, Rabi
The refrigerants used in traditional vapor compression refrigeration systems are harmful to the ozone layer and contribute to global warming. The demand for refrigeration is increasing because of global warming. In this study, for the first time, an energy, exergy, environmental, and enviroeconomic (4E) analysis was performed using different refrigerants and nanoparticles to reduce the energy required in low-temperature vapor compression cascade refrigeration systems and to determine more environmentally friendly nanorefrigerants. The R290 refrigerant was used for the Low-Temperature Circuit (LTC), while the High-Temperature Circuit (HTC) used RE170, R1234yf, R600, R600a, and R450A refrigerants. The nanoparticles used in the analysis were Al2O3, CNT, CuO, TiO2, ZnO, and SiO2. The R600 nanorefrigerant performed the best, whereas the R1234yf nanorefrigerant performed the worst. The results indicate that the CuO nanoparticles provided the highest performance. In addition, the results showed that the R290+R600-CuO nanorefrigerant emitted 11 % less CO2 than the pure R290+R600 refrigerant. The nanorefrigerants provide a more environmentally sustainable option because of their high efficiency and lower energy consumption than conventional refrigerants.
AtıfScopus9WoS7OpenAlex8İncele - MakaleAçık Erişim2024Scopus SJRQ1Analysis of cascade vapor compression refrigeration system using nanorefrigerants: Energy, exergy, and environmental (3E)
Yilmaz, Metin; Cimsit, Canan; Keven, Arzu; Karaali, Rabi
Nanorefrigerants are considered the most efficient heat transfer fluids for improving heat transfer properties in the refrigeration and air conditioning equipment. For the first time in this study, energy, exergy, and environmental evaluation (3E) analyses were performed by the addition of different nanoparticles to a low GWP refrigerant pair such as R290/R1233ZDE in a cascade refrigeration system. CNT, CuO, and, TiO2 nanoparticles were added to the refrigerant. The effect of nanoparticles on the cascade refrigeration system was analyzed using a model based on density changes. A detailed thermodynamic analysis was performed of the cascade refrigeration system at different evaporator temperatures and mass ratios. The power consumption of the compressor decreases as the evaporator temperature increases for all types of nanoparticles, resulting in an increase in COP values. The analyses showed that CuO nanoparticles had the highest performance. It has been observed that the energy and exergy efficiency increase as compressor work decreases with increasing mass ratios in all nanorefrigerants. In addition, the results indicated that all nanorefrigerants emit lower monthly CO2 emissions compared to the pure refrigerants. The nanorefrigerants play a crucial role in reducing energy consumption and promoting environmental protection compared to traditional refrigerants.
AtıfScopus16WoS16OpenAlex17İncele - MakaleYalnız künye2024Scopus SJRQ2Drought analysis using innovative trend analysis and machine learning models for Eastern Black Sea Basin
Niazkar, Majid; Piraei, Reza; Eryılmaz Türkkan, Gökçen; Hırca, Tuğçe; Gangi, Fabiola; Afzali, Seied Hosein
This study aims to assess the Eastern Black Sea Basin drought conditions. For this purpose, the trend changes in SPI values of 6, 9, 12, and 24 months using innovative trend analysis were examined. Additionally, four machine learning models, including Multiple Linear Regression, Artificial Neural Networks, K Nearest Neighbors, and XGBoost Regressor, are employed to forecast SPI with rainfall data between 1965 and 2020 from eight rainfall stations. The input data for each model was SPI values from lead times of 1 to 6, resulting into 768 unique scenarios. The ML models estimated SPI values better as the SPI duration increased, with the 24-month SPI showing the highest accuracy. The results of SPI forecast indicated that the optimal model and number of input variables varied for each SPI and station, indicating that further studies are required to improve SPI predictions.
AtıfScopus24WoS23OpenAlex25İncele - MakaleAçık Erişim2024Scopus SJRQ3Exergetic Analyses of Detonation Engine Cogeneration Plants
Çakmak, Bahar; Karaali, Rabi
Efficiency improvements are very important in all research and technology. Detonation engines are high technology devices. In the last decades they attracted attention by many researchers. However, detonation engines for cogeneration are not researched efficiently. This article is about the detonation engines cogeneration cycles which analysed by using 1. and 2. law of thermodynamics and exergy analyses methods by the authors. The exergetic performance analyses, their advantage and disadvantages of the ZND-HRSG detonation engine cogeneration cycles were obtained. The exergetic performance analyses were done for various excess air rates to obtain the variations of the combustion exit pressures and temperatures, exergy efficiencies, electric heat rates, SFC and other parameters of their performance. Also, an optimization analysis was done for the ZND-HRSG by searching the optimum values for different excess air rates. The results showed that, the ZND-HRSG cycle have the optimum values of the performance at 1.6-1.8 of the excess air rates.
AtıfScopus1OpenAlex5
İncele - Kitap BölümüAçık Erişim2024Assessment of glass
Cuce, Erdem; Cuce, Pinar Mert; Guclu, Tamer
Especially for new-generation buildings, since esthetic appearance as well as thermal comfort is essential, glass materials have been widely used as building materials in buildings. Due to its superior optical properties, it is preferred in buildings, especially in window areas. On the other hand, the heat losses and gains and light transmission rates from the glass used in the building envelopes and especially in the window areas are very effective on the energy efficiency of the buildings. Therefore, innovative glass technologies are developed and used in new smart buildings. In this context, the most preferred glass technologies are laminated glass and tempered glass for the building envelope. For window areas, it can be listed as low emissivity glasses, high-technology glasses, vacuum glasses, glasses with phase change materials and insulated glasses.The use of new-generation glass technologies instead of traditional glass technologies provides significant benefits to users regarding economic, environmental, and social effects.
AtıfScopus1İncele - MakaleYalnız künye2024Scopus SJRQ1Variations of natural frequencies of masonry minarets due to environmental effects
Yanik, Yusuf; Aymelek, Abdullah; Yildirim, Ömer; Demirtaş, Betül; Türker, Temel
It is very important to distinguish the reason of change in natural frequencies of structures either caused by a possible damage or environmental conditions (temperature and humidity). In this study, the changes in the dynamic properties of masonry and reinforced concrete minarets under environmental effects, such as temperature and humidity, were investigated. The masonry minarets of İskenderpaşa, Hacı Kasım, and Tavanlı Mosques and the reinforced concrete minarets of Karadeniz Technical University, Dilaveroğlu and Papatya Mosques in Trabzon were monitored by ambient vibration test method, and the relationship between natural frequencies and temperature and humidity was tried to be determined. For this purpose, the natural frequencies of these minarets were measured at certain intervals under different temperature and humidity conditions over a period of approximately 6 months. The vibration measurement system which was developed by our research team was used in the measurements. From the data collected by these measurements, the variation intervals of the natural frequencies (the smallest and the highest values), the percentages of change and their relations with temperature and humidity were revealed. This relationship was determined using linear–non-linear simple and multiple regression analyses. From this study, it was found that the natural frequencies change under environmental effects, such as temperature and humidity, and this rate of change was approximately 7%. There was moderate correlation in Tavanlı, Dilaveroğlu, and Papatya Minarets, and strong correlation in Hacı Kasım Minaret.
AtıfScopus16WoS17OpenAlex16İncele - MakaleAçık Erişim2024Scopus SJRQ1Thermal and energy analysis of a novel solar updraft tower design with divergent chimney and convergent collector concept: CFD analysis with experimental validation
Cuce, Pinar Mert; Saxena, Abhishek; Cuce, Erdem; Kontoleon, Karolos J.; Oztekin, Erman K.; Shaik, Saboor; Guo, Shaopeng
The fact that energy sources are heavily dependent on fossil fuels increases the need for alternative energy day by day. Solar energy is the most popular alternative energy source with massive potential. Solar chimney power plants (SCPP) are one of the systems of interest based on solar energy. SCPP systems are rare systems that can provide 24-hour power output. Their performance has been the subject of constant research since the first pilot plant in Manzanares. Design is crucial for performance figures of SCPPs, and the limitation of climatic parameters causes the system to be approached with different designs. This study makes a 3D CFD model by combining the divergent chimney and convergent collector structure based on the first pilot plant. The solar ray tracing algorithm and the RNG k-e turbulence model are applied and the model equations are solved under dynamic conditions with the reliable software ANSYS FLUENT. After the mesh-independent solution of the model is complete, it is validated with experimental data. The two cases are compared for solar radiation of 1000 W/m2 and environmental temperature of 293 K. A power output of 50.51 kW is achieved for standard pilot sizing. With the new model, the power output rises to 146.34 kW. It is seen that the divergent chimney and convergent collector affect the airflow in the system, increasing the maximum air velocity to 19.363 m/s. In parallel with the experimental data, it is seen that the temperature on the ground exceeds 360 K in the CFD results.
AtıfScopus17WoS12OpenAlex14İncele - MakaleAçık Erişim2024Scopus SJRQ2Determinants of Ecological Footprint: A Quantile Regression Approach
Özcan, Kübra Akyol
Through the examination of the ecological consequences of human actions, policymakers are able to distinguish certain areas in which resource use can be increased and the generation of waste diminished. This study examines the effects of foreign direct investment, gross domestic product, industrialization, renewable energy consumption, and urban population on the ecological footprints in 131 countries between 1997 and 2020. The objective of this study is to establish a thorough understanding of the relationship between these variables and ecological footprints while considering temporal changes from economic and environmental aspects. The analysis of a substantial dataset encompassing many countries aims to uncover recurring patterns and trends that can provide valuable information for the formulation of policies and strategies pertaining to sustainable development on a global level. The study fills a significant gap in the knowledge on the ecological impact of different variables, providing a nuanced understanding of the interdependencies among these factors, thus guiding sustainable development strategies, and promoting global sustainability. The study utilizes quantile regression analysis, a nonparametric estimator, to estimate consistent coefficients. The statistical analysis reveals that FDI, urbanization, and GDP have statistically significant and positive effects on ecological footprints. Industrialization and renewable energy consumption show significant and negative relationships with ecological footprints. The findings of this study contribute to the understanding of the relationships among these variables and provide insight to inform policy and decision-making efforts focused on reducing ecological consequences and advancing sustainable development goals.
AtıfScopus16WoS13OpenAlex21İncele - MakaleYalnız künye2023Mekânsal Panel Modelleri Kullanılarak Yenilenebilir Enerji Tüketimi, Çevresel Bozulma ve Büyüme İlişkisinin İncelenmesi: Balkan Ülkelerinden Kanıtlar
Arı, Ari; Bayramoglu, Turgut; Sayar, Ramazan
Amaç: Bu çalışmayla karbon salınımının Balkan ülkeleri ve Türkiye'nin büyümesine etkisinin olup olmadığının, eğer varsa, bu etkinin ne yönde ve ne yoğunlukta olduğunun bulunması amaçlanmıştır. Yöntem: Bu çalışmada karbon emisyonları ve yenilenebilir enerji üretiminin Türkiye ve 12 Balkan ülkesinin büyümesine etkileri analiz edilmiştir. Çalışmada mekânsal etkileşimleri ortaya çıkarabilmek için Mekânsal Otokorelasyon Analizi yapılmıştır. Büyümeyi etkileyen faktörleri incelemek için ise Havuzlanmış En Küçük Kareler yöntemi kullanılmıştır. Bulgular: Çalışmanın sonuçlarına göre Balkan ülkelerinde yenilenebilir enerjinin büyüme üzerindeki olumsuz etkisinin, yenilenebilir enerjinin henüz gelişme aşamasında olması ve üretimdeki payının hala düşük olmasından kaynaklandığı söylenebilir. Yenilenebilir enerji sektöründeki yatırımların sınırlı olması yenilenebilir enerji sektörünün yavaş yayılmasına neden olmaktadır. Özgünlük: Çalışmada farklı bir yöntem olarak mekânsal panel modellerinin kullanılması ve kapsamın Türkiye ile sınırlı tutulmayıp tüm Balkan ülkelerini de kapsaması bu çalışmanın özgün değerini oluşturmaktadır.
AtıfOpenAlex1İncele - MakaleAçık Erişim2023Scopus SJRQ3Socio-economic determinants of environmental degradation: Empirical evidence for the Environmental Kuznets Curve
Gültekin, Ömer Faruk; Sayar, Ramazan; Ari, Yllmaz Onur
The aim of the paper is to examine socio-economic determinants of environmental degradation. The empirical study employs quantile regression which enables separate predictions for different levels of the dependent variable to be made. This study investigated 62 countries from low, middle and some high income countries for 1995-2019. The Environmental Kuznets Curve (EKC) is verified for the aforemented countries in analyzing the relationship between economic growth and carbon emissions using quantile regression. The study also revealed that the schooling rate has a pollution-increasing effect. In addition to the reducing effects of trade openness, democracy, and economic freedom variables on environmental degradation, the opposite effect of life expectancy at birth is observed, increasing environmental degradation. In this context, this paper concluded that the EKC hypothesis is not supported. The government should encourage pollution-reducing policies in low and middle income countries.
AtıfScopus4WoS3OpenAlex5İncele - MakaleAçık Erişim2023Performance Analyses of Combined Cycle Power Plants
Karaali, Rabi
In this article, different compressor pressure and different excess air rates for a gas turbine based combine cycle power plant with steam Rankine cycle as bottoming cycle were analyzed by using 1. and 2. laws of thermodynamics and exergy analyses methods to obtain the best performances of the cycle. Exergy efficiency of the cycle, net powers of the gas and steam turbines and the overall cycle, exergy loss of the components, the efficiencies of the components are obtained, compared and discussed. It was found that, increasing the compressor pressure increases exergy efficiency of cycle, gas turbine and total plant power, and the combustion chamber, the HRSG and the compressor efficiencies. However, increasing compression rates decreases steam turbine power, combustion chamber, steam turbine, and HRSG exergy losses and the gas turbine efficiency. Also, it is found that, increases in excess air ratios gives an optimum or a maximum exergy efficiency, at 2.5 excess air rate of the cycle.
AtıfScopus3OpenAlex6İncele - MakaleAçık Erişim2023Scopus SJRQ1Sustainability Ranking of Turkish Universities with Different Weighting Approaches and the TOPSIS Method
Akyol Özcan, Kübra
The concept of sustainability has become more important, especially as a result of the depletion of energy resources and increasing environmental concerns. UI GreenMetric ranks universities based on sustainability, environmental, and energy concerns, addressing issues of environmental pollution, food and water scarcity, and energy supply. By prioritizing sustainability on their campuses and campuses, universities are working to ensure a more sustainable future for humanity. This study evaluates university sustainability in energy and climate change using the UI GreenMetric ranking, focusing on Turkish universities’ sustainability ranking. It incorporates variables like infrastructure, energy, climate change, waste, water, public transportation, and educational research, using weighting approaches to reveal the most important variables for the country’s universities. The study utilized weighting techniques like CRITIC, entropy, standard deviation-based, and equal weighting approaches to obtain rankings for UI GreenMetric rankings. Entropy and equal weighting methods were found to be closest to the UI GreenMetric rankings. Universities’ rankings were analyzed using the TOPSIS method and four weighting techniques for 83 Turkish universities. For Turkish universities, the CRITIC method yielded the highest weight for energy and climate change variables, while water was identified as the most significant factor for entropy, installation infrastructure, and standard deviation-based weighting techniques.
AtıfScopus13WoS11OpenAlex15İncele - MakaleAçık Erişim2023Scopus SJRQ1A novel ignition timing strategy to regulate the energy balance during the warm up phase of an SI engine
Koksal, Hüseyin; Ceviz, Mehmet Akif; Yakut, Kenan; Kaltakkiran, Galip; Özakin, Ahmet Numan
The warm up characteristics of an engine have a significant impact on engine performance and exhaust emissions. In SI engines, the light-off performance of the catalytic converter is also important. One of the methods used to shorten the light off time of the catalytic converter is to retard the ignition time. When the ignition time is retarded, the temperature of the exhaust gases increases. However, in this case, the warm up performance of the engine itself may be adversely affected. In this study, firstly, the effects of ignition timing on the energy balance during the warm up period in an SI test engine were revealed. Then, a novel ignition timing strategy was proposed in order to increase the temperature of the exhaust gases, and not to reduce the engine performance. The novel ignition timing strategy working on the principle of sequentially advanced and retarded ignition at certain intervals during the warm up period provides several advantages. When the novel ignition strategy is applied, the energy loss through the exhaust gas was increased up to 7.2% for several operating conditions, while the reduction in engine performance is eliminated. Moreover, 20% reduction in NO emission has been achieved.
AtıfScopus8WoS8OpenAlex7İncele - MakaleAçık Erişim2022Bayburt İli Hava Kirliliğinin İstatistiksel Yöntemlerle Analizi
Bayraktar, Hanefi; Türkkan, Gokçen Eryılmaz; Hırca, Tuğçe
Bu çalışmada Bayburt şehir merkezine ait hava kirleticilerinin zamansal değişimleri, yerel meteorolojik parametreler ile olan etkileşimleri ve trendleri istatistiki yöntemlerle analiz edilmiştir. Bu kapsamda, 2017-2019 dönemi saatlik ölçülen PM10, SO2, NO, NO2, NOX ve O3 ile saatlik sıcaklık (t), rüzgâr hızı (ws), nem (rh) ve basınç (p) verileri analiz edilmiştir. Birincil kirleticilerden PM10 konsantrasyonlarının ortalama değeri 40.5 μg/m3 ve SO2 konsantrasyonlarının ortalama değeri ise 6.85 μg/m3 olarak tespit edilmiştir. Mann-Whitney U testi sonuçlarına göre, kirletici konsantrasyonlarının soğuk mevsim ortalamaları sıcak mevsim ortalamalarından istatistiki manada anlamlı şekilde farklılaştığı tespit edilmiştir (p=0.000<0.05). Kruskal Wallis testine göre kirletici konsantrasyonlarının yıllara göre ortalamaları arasında da istatistiksel açıdan anlamlı bir farklılaşma olduğu saptanmıştır (p=0.000<0.05). Hangi yıllar arasında farklılaşmanın olduğu Post-Hoc/Tamhane’s T2 analizi ile belirlenmiştir. Spearman’s rho korelasyon analizi sonuçları hava kirleticiler ile meteorolojik parametreler arasında istatistiki manada anlamlı bir ilişki ortaya koymaktadır (p=0.000<0.05). Buna göre, PM10 ile bağıl nem arasındaki ilişkinin negatif yönlü, SO2 ile hava basıncı arasındaki ilişkinin pozitif yönlü, NO, NO2 ve NOX ile rüzgâr hızı ve sıcaklık arasındaki ilişkinin negatif yönlü, O3 ile sıcaklık ve rüzgâr hızı arasındaki ilişkinin pozitif yönlü olduğu tespit edilmiştir. Yenilikçi trend analiz yöntemi (ITA) sonuçlarına göre, PM10 seviyeleri azalış, diğer kirleticiler ise artış eğilimi göstermektedir. Kullanılan verilerin zaman aralığı göz önüne alındığında kirletici ortalamalarının her ne kadar sınır değerleri aştığı gözlenmese de kirleticilerin artış eğiliminde olması, pozitif hava kalitesinin korunması için daha fazla çaba gösterilmesi gerektiğini ortaya koymaktadır. Çalışmadaki istatistiksel veri analizleri SPSS 22 programı ile gerçekleştirilmiştir.
AtıfOpenAlex3TR Dizin2İncele - MakaleAçık Erişim2022Scopus SJRQ3Turkey's Long-Term Electricity Consumption Forecast
Emec, S.; Akkaya, G.
Demand forecasting is essential primarily for planning. Although it is crucial in many sectors and issues, it has particular importance for electricity. Therefore, the issue of electricity consumption forecasting has recently become a prevalent topic. In light of the above, this study aimed to develop an appropriate model to estimate the long-term electricity consumption of Turkey. The study consists of three steps. In the first step, eight models were developed to separately investigate the effects of eight input variables frequently used in electricity consumption forecasting studies in the literature. In the second step of the study, two models consisting of input variables with high impact in the first step were developed, and the trained performances of the developed models were calculated by using the regression analysis. In the final step, the combined effect of eight variables on electricity consumption forecasting was investigated using regression analysis. It can be conclude that the model in the third step showed significant results, and the model performance was good. Finally, Turkey's electricity consumption forecast for the years 2020-2030 was performed using the model in the third step.
AtıfWoS1OpenAlex3İncele
