TR Dizin İndeksli Yayınlar Koleksiyonu / TR Dizin Indexed Publications Collections

Permanent URI for this collectionhttps://hdl.handle.net/20.500.13091/4

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Citation - WoS: 6
Citation - Scopus: 9
Ağaç-tohum Algoritmasının Cuda Destekli Grafik İşlem Birimi Üzerinde Paralel Uygulaması
(2018) Çınar, Ahmet Cevahir; Kıran, Mustafa Servet
Son yıllarda toplanan verinin artmasıyla birlikte verimli hesaplama yöntemlerinin de geliştirilmesi ihtiyacı artmaktadır. Çoğunlukla gerçek dünya problemlerinin zor olması sebebiyle optimal çözümü garanti etmese dahi makul zamanda yakın optimal çözümü garanti edebilen sürü zekâsı veya evrimsel hesaplama yöntemlerine olan ilgi de artmaktadır. Diğer bir açıdan seri hesaplama yöntemlerinde verinin veya işlemin paralelleştirilebileceği durumlarda paralel algoritmaların da geliştirilmesi ihtiyacı ortaya çıkmıştır. Bu çalışmada literatüre son yıllarda kazandırılmış olan popülasyon tabanlı ağaç-tohum algoritması ele alınmış ve CUDA platformu içerisinde paralel versiyonu geliştirilmiştir. Algoritmanın paralel versiyonunun performansı kıyas fonksiyonları üzerinde analiz edilmiş ve seri versiyonunun performansı ile karşılaştırılmıştır. Kıyas fonksiyonlarında problem boyutluluğu 10 olarak alınmış ve farklı popülasyon ve blok sayıları altında performans analizi yapılmıştır. Deneysel çalışmalar algoritmanın paralel versiyonunun algoritmanın seri sürümüne göre bazı problemler için 184,65 kata performans artışı sağladığı görülmüştür.
Alström Syndrome With Liver Cirrhosis: First Case From Turkey
(2013) Ataseven, Hüseyin; Güngör, Gökhan; Demir, Ali; Biyik, Murat; Uçar, Ramazan; Esen, Hasan; Çakır Özer, Özlem
Alström sendromu çocukluk çağında trunkal obezite, insülin direnci ve hiperinsülinemi, tip 2 diyabet, hipertrigliseridemi, yetişkinlikte boy kısalığı, kardiyomyopati ve ilerleyici akciğer, karaciğer ve böbrek fonksiyon bozukluğu, işitme kaybı, gözde koni-çomak distrofisi ile karakterize otozomal resesif geçişli genetik bir hastalıktır. Alström sendromu karaciğer sirozunun oldukça nadir bir sebebidir. Alström sendromlu hastaların post-mortem biyopsilerinde karaciğer, böbrek, kalp ve akciğerler gibi birçok organda fibro- sis gösterilmiştir. Bilinen karaciğer sirozu olmayan ve acil servise özofagus varis kanaması ile başvuran Alström sendromlu bir vaka sunmaya çalıştık.
Citation - WoS: 8
Citation - Scopus: 9
Amplifying the Dielectric Constant of Shellac by Incorporating Natural Clays for Organic Field Effect Transistors (ofets)
(TUBITAK, 2023) Kim, S.; Yumuşak, Ç.; Irimia, C.V.; Bednorz, M.; Yenel, E.; Kuş, M.; Sariçiftçi, N.S.
We demonstrate in this work the practical use of uniform mixtures of a bioresin shellac and four natural clays, i.e. montmorillonite, sepiolite, halloysite and vermiculate as dielectrics in organic field effect transistors (OFETs). We present a thorough characterization of their processability and film forming characteristic, surface characterization, elaborate dielectric investigation and the fabrication of field effect transistors with two classic organic semiconductors, i.e. pentacene and fullerene C60. We show that low operating voltage of approximately 4 V is possible for all the OFETs using several combinations of clays and shellac. The capacitance measurements show an improvement of the dielectric constant of shellac by a factor of 2, to values in excess of 7 in the uniform mixtures of sepiolite and montmorillonite with this bioresin. © TÜBİTAK.
Citation - WoS: 1
Citation - Scopus: 5
An Application on the Use of Fuzzy Multi Criteria Decision Making Methods for Software Project Development Process Selection
(Gazi Univ, Fac Engineering Architecture, 2023) Yel, İbrahim; Baysal, Mehmet Emin
Software development projects are difficult to manage, as they involve complex business stages and the resources used are made up of real people. Along with the specifications of the projects, organizational variables and the competencies of the team members are among the factors that will directly affect the success of the project. It is thought that the success of software development projects will increase with the use of these three factors in the solution of the software development process method selection problem. In the management of software projects, different process methods are used, including Agile and Waterfall (Traditional) Methods. It is important to assign development teams to projects according to their abilities and to rank the projects among themselves. As a first step in this study, the weights of the criteria were determined using the fuzzy AHP. Then fuzzy WASPAS, fuzzy EDAS and Interval Neutrosophic Z Numbers (NZN) methods were used to rank projects and employees. According to the results of this research with sensitivity analysis, it has been determined that if the software development method decision is implemented, the number of defects and their solutions can be improved by 4.2%-6%, 5.8%-7.3% and 6.8%-9.7% when compared to the actual values of person-day values.
Chromatographic Evaluation of Tocols and Sterols of Processed Canola Oil and Deodorizer Distillate
(TUBITAK, 2022) Shoaib, H.; Sherazi, S.T.H.; Naz, S.; Mahesar, S.A.; Khaskheli, A.R.; Uddin, S.; Topkafa, Mustafa
Tocopherols and tocotrienols in the combined form are known as tocols. Changes of total and individual tocols and sterols concentration of canola oil and deodorizer distillate (DD) during different processing stages were evaluated with the application of gas chromatography (GC) and high-performance liquid chromatography (HPLC). For sterols analysis, GC coupled with flame ionization detector (FID) was used while tocols in canola oil samples and DD, normal phase (NP) HPLC was applied. The results of the present study indicated that levels of total and individual tocols and sterols content were decreased during processing (neutralization to deodorization). Deodorization was found to be the most effective process for the reduction of total sterols and tocols as 55.9% and 34.2%, respectively. A high amount of tocols and sterols was observed in DD. Among tocols and sterols; beta tocopherol (?-T) and ?-sitosterol were found to be in greater concentration 53.97% and 31.82%, respectively. Therefore, DD could be used as a valuable by-product in the cosmetics and food industries. © 2022 TUBITAK. All rights reserved.
Citation - WoS: 1
Citation - Scopus: 1
Çoklu İHA’larla Kısıt Tatmin Problemi Temelli Çok Amaçlı Görev Planlaması
(Gazi University, Faculty of Engineering Architecture, 2025) Atay, Yılmaz; Ayvaz, Emre; Babaoğlu, İsmail
İnsansız hava araçlarının dahil olduğu çoklu görev planlama problemleri; zamana bağlı görevler ve çeşitli türdeki araçların sensör, konum, yakıt, faydalı yük vb. farklı yetenek ve kısıtlarına bağlı olarak ne tür görevleri yapabileceğinin belirlenmesini ve bunların planlamasını ifade eder. Bu problem, Kısıt Tatmin Problemi (KTP) olarak modellenebilmektedir. Zamansal KTP (ZKTP) ise ardışıl görevlerin, zamansal anlamda görev ikililerine bölünerek KTP üzerine inşasını modeller. Bu işleme bağlı olarak görev isterleri ile İnsansız Hava Aracının (İHA)’nın yetenekleri arasındaki statik ve dinamik kısıtlara bağlı olarak gerçekleştirebilecek eylemler ile ilgili baskın bir çözüm kümesi aranır. Böylece görevler ile mevcut İHA’ların yetenekleri arasındaki ilişki, zamansal boyutta irdelenerek çok amaçlı problemleri optimize eden aday çözümler bulunur. İyileştirilmiş ZKTP (İZKTP) yönteminde KTP’deki aç gözlü yaklaşım yerine, etki alanındaki en yüksek puana sahip İHA’nın göreve atanması önerilmiştir. Ek olarak, iyileştirilmiş ileri kontrol yöntemiyle bir sonraki görevin etki alanındaki İHA'ların gerçek zamanlı konumlarına ve zamanlarına göre atama durumu değerlendirilebilmektedir. Bu çalışmada, yakıt tüketimini ve toplam havada kalma süresini en aza indiren uygun bir çözüm kümesinin KTP ile aynı zaman karmaşıklığı içinde bulunması amaçlanır. Burada, zamansal kısıt tatmin modeli gerçeklenmiş ve çeşitli görevlerde karmaşıklığı aşamalı olarak değiştirilerek geri izleme (Backtracking), ileri kontrol (Forward Checking), yay tutarlılığı (Arc Consistency), düğüm tutarlılığı (Node Consistency) yöntemleriyle önerilen yaklaşımın performansı, deneysel çalışmalarla doğrulanmıştır. Bu kapsamda yapılan deneyler iki farklı aşamayı içermektedir. İlk aşamada, çeşitli yetenek ve kısıtlara sahip İHA'ların farklı isterleri olan görevlere atanmasını içeren farklı simülasyonlar gerçekleştirilmiştir. Buradaki simülasyonlarda olası gerçek senaryolardan esinlenen sentetik veriler kullanılmıştır. İkinci aşamada ise atamalar sonrası dinamik programlama temelli etki alanı güncellemesiyle görev ikililerinin zaman pencerelerinde değişen süreçleri takip eden düğüm kontrolü, geri izleme, ileri kontrol ve yay tutarlılığı yaklaşımları kullanılmıştır. Önerilen KTP ile gerçekleştirilen testler sonucu sekiz farklı görev içeren iş paketinde, KTP ile benzer zaman karmaşıklığında daha uygun maliyet ve zaman çıktıları elde edilmiştir. Testler kapsamında 64 farklı görev içeren bir problem için önerilen yöntem, standart KTP’ye göre12 adet daha az İHA kullanılmasını sağlayarak önemli bir performans artışına ulaşmıştır.
Citation - WoS: 3
Citation - Scopus: 4
A Comparison of Rans-Based Turbulence Modeling and Piv Experiments for Flow Over a Simplified Road Vehicle
(Gazi Universitesi, 2023) Aksoy, M.H.; Okbaz, A.; Yaǧmur, S.; Doǧan, S.
The aerodynamic forces on road vehicles and flow structures around them result from complex interactions between fluid and structure. Ahmed body is a simplified car model created to demonstrate and simplify the flow around real-size ground vehicles. In this study, the flow structure on the wake region of Ahmed body with different slant angles (Θ=15°, 25°, and 35°) was investigated. Experimental studies were conducted in a water channel by Particle Image Velocimetry (PIV). The freestream velocity was set to 0.2 m/s, and the Reynolds number defined by the characteristic length of the Ahmed body was 4.16×104 for Computational Fluid Dynamics (CFD) and PIV experiments. CFD simulations were performed using three different turbulence models: realizable k-ϵ, RNG k-ϵ, and SST k-ω, and the results were compared to experiments. The results are presented with different flow features such as time-averaged velocity vectors and velocity contours, streamline topology, vorticity, and Turbulence Kinetic Energy. The closest results to the experiments were obtained by the SST k-ω turbulence model for all slant angles of the Ahmed body. In addition, the drag coefficient is found to be 0.37 for all slant angles analyzed by SST k-ω turbulence models, which are also close to the results in the literature. © 2023 Gazi Universitesi Muhendislik-Mimarlik. All rights reserved.
Citation - Scopus: 11
A Critical Evaluation of Maximum Power Point Tracking Techniques for Pv Systems Working Under Partial Shading Conditions
(2023) Omar, Fuad Alhaj; Pamuk, Nihat; Kulaksız, Ahmet Afşin
Photovoltaic (PV) energy is a promising source of renewable energy which is sturdy and environmentally friendly. PV generation systems, once installed, produce electricity from solar irradiance without emitting greenhouse gases. To maximize the output power of PV systems, the maximum power point tracking system has been employed (MPPT). The MPPT constitutes a fundamental part of PV systems. In recent years, a large number of MPPT techniques have been proposed. This paper is set up to critically review some of the proposed maximum power point tracking (MPPT) techniques to handle the emergence of multiple MPPs in PV panel characteristics due to the partial shading conditions (PSCs). To define the working principle and the pros and cons of the different proposed techniques clearly and sequentially, they are divided into three groups as follows: conventional MPPT techniques, improved MPPT techniques and artificial intelligence- based MPPT techniques to deal with PSCs. The paper also critically summarizes the findings in terms of their performance in capturing the global maximum power point (GMPP) for PV systems operating under PSCs.
Citation - WoS: 5
Citation - Scopus: 4
Design, Manufacture and Thermal Analysis of a Single Pass Solar Air Collector at Different Mass Flow Rates
(GAZI UNIV, FAC ENGINEERING ARCHITECTURE, 2020) Darıcı, Selçuk
Solar air collectors are generally used for drying industrial and agricultural products or for space heating. Nowadays solar energy is paid more attention due to decrease in fossil fuels and increase in energy prices. In this study, a single pass, forced convective solar air collector has been designed, manufactured and analysed experimentally under climatic conditions of Konya/Turkey. Experiments have been conducted at three different mass flow rates, on different days and under clear weather conditions. Hourly variation of solar radiation, inlet and outlet air temperatures, glass cover temperature, absorber plate temperature and thermal efficiency of the solar air collector have been examined by using the experimental data obtained. It is seen that with the increase in mass flow rate, temperature of the air at the outlet of the collector decreases while thermal efficiency of the collector increases.
Citation - Scopus: 1
Determination of Environmental Valuation of Bey?ehir Lake National Park by Travel Cost and Contingent Valuation Methods
(Gazi Univ, Fac Engineering Architecture, 2023) Karakayacı, Zühal; Karakayacı, Özer; Polat, Ahmet Tugrul
With the increasing population of the world, developments such as unplanned growth, urbanization, industrialization and accordingly climate change have necessitated the protection of natural resources. In this context, National Parks are the leading natural resources under protection. Since national parks are natural assets used for recreational and tourism purposes, they provide important contributions to the country's economy as well as the social benefit they provide to the society. Therefore, natural resources need to be included in the calculations of national income, which is a measure of the growth rate of countries, and economic value determination is needed for this. For this purpose, Beysehir Lake National Park, which is the second largest national park, has been valued. Contingent Valuation Method and Travel Cost Method are used in the appraisal. During the data collection phase, 383 samples were determined using the Proportional Sampling Method, and the surveys were conducted with visitors within the national park in the summer of 2019. According to the Conditional Valuation Method, 186.838.123 TL was calculated, 453.612.000 TL according to the Travel Cost Method and the total economic value was determined as 640.450.123 TL. The consumer surplus per visitor, that is, the fee that a visitor is willing to pay for a visit to the national park in one year, was calculated as 2.202 TL. All findings obtained with a stake in the country's national income in light of the economic value of Turkey and the second largest national park was revealed the existing potential. Its economic value should be evaluated in development policies, and its existing potential should be presented to the social benefit of people by protecting it within the framework of environmental protection policies.
Citation - Scopus: 2
Effect of Pyrolysis Char Produced From Co-Pyrolysis of Waste Sycamore Leaves and Plastic Cups on Bitumen Viscosity and High Temperature Performance Grade
(Gazi Universitesi, 2021) Atasağun, Neslihan
In this study, the effects of pyrolysis char produced from co-pyrolysis of waste sycamore leaves and plastic cups on bitumen viscosity and high temperature performance grade were investigated. For this purpose, 50/70 penetration bitumen was modified with pyrolysis char produced by weight of 6% and 12% ratios in bitumen. Softening point test, penetration test, dynamic shear rheometer (DSR) test and rotational viscosity (RV) test were applied on pure bitumen and modified bitumens, also temperature susceptibility of bituminous binders were evaluated by determining the PI values. As a result, it was detected that pyrolysis char used as additive by weight of 6% and 12% ratios in bitumen increased the viscosity of pure bitumen approximately 33% and 83% ratios at 135?, increased the rutting resistance of pure bitumen 46% and 24% ratios at 70? respectively and increased the high temperature PG of pure bitumen. © 2021 Gazi Universitesi Muhendislik-Mimarlik. All rights reserved.
Citation - WoS: 1
Citation - Scopus: 1
Effects of Conventional and Flash Sintering Methods on the Properties of Zro₂-sno₂nanocomposites
(Gazi Univ, Fac Engineering Architecture, 2024) Cetinkaya, Zeynep
ZrO2-SnO2 nanocomposite was produced in nanofiber (NF) form in three different ratios by volume (%v/v)by electro-spinning technique. Microstructure and morphological characterization of NFs reveal the ternarysystem of ZrO2-SnO2-ZrSnO4. Also, when the composition ratio of NFs was changed, both the band gap andthe electrical (flash) sintering (ES or FS) event affected the temperature and sinter time variation. FSexperiments were used at 3.77mA/mm2 current cutoff under thermal (844-878 degrees C) and electric field(420V/mm). Highly dense nanocomposites were obtained in less than 80 seconds with a maximum powerabsorption of 1.58W/mm3. Thanks to the low sintering temperature and time, the nanostructured surfacemorphology of the nanocomposites was obtained. In addition to the FS process, ZrO2-SnO2-ZrSnO4 CNFs were sintered for 1 hour at 1200 degrees C using the conventional sintering (GS) method. This study investigatedthe effects of the difference in sintering techniques on the sintering temperature and time, as well as onproperties such as density and hardness. As the amount of Sn (%v/v) in the composition increases, the density increases, but the hardness value decreases. It has been proven that in ZrO2-SnO2-ZrSnO4 CNFs, denser and harder compositions are obtained with FS treatment compared to GS. When all these results are evaluated, it is believed that the synthesized nanocomposites can be used as a valid candidate in the health system such as dental implants due to their antimicrobial effect and non-toxicity in the model organism
Enhanced Uptake Capacities and Isosteric Heats of Co2 and Ch4 Adsorption on Spent Coffee Ground Activated Carbons Loaded With Metal Ions
(2019) Kırbıyık, Çisem; Büyükbekar, Burak Zafer; Kuş, Mahmut; Ersöz, Mustafa
Low-cost activated carbon (AC) samples obtained from waste coffee grounds were used for CO2 and CH4 adsorption. ACs were prepared by chemical activation and carbonized at three different temperatures. AC carbonized at 800 ? C showed a relatively high surface area (582.92 m2 g ?1 ) and high adsorption capacities of 2.6 mmol g ?1 and 1.1 mmol g ?1 at 25 ? C for CO2 and CH4 , respectively. Adsorbent samples were prepared by loading of Fe 3+ metal ions onto ACs and their adsorption capacities were compared with those of nonloaded ACs. As expected, the loading of Fe 3+ metal ions increased the adsorption capacities at all temperatures and the adsorption capacity of Fe 3+ -loaded AC carbonized at 800 ? C was 3.1 mmol g ?1 for CO2 and 1.2 mmol g ?1 for CH4 at 25 ? C. The isosteric heats of adsorption were calculated at 0–35 ? C with the range of 20–35 kJ mol ?1 and 18–23 kJ mol ?1 for CO2 and CH4 , respectively. According to our findings, bio-based ACs can be used as an effective and alternative adsorbent for capturing different gas molecules.
Citation - WoS: 3
Citation - Scopus: 3
Estimation of Turkey’s Natural Gas Consumption by Machine Learning Techniques
(2020) Erdem, Osman Emin; Kesen, Saadettin Erhan
Technological advancements coupled with growing world population require the increasing need of energy. Natural gas is one of the most important usable energy resources. Turkey is with high external dependency on energy as it has its own limited natural and underground energy resources. Thus, in order to effectively and productively use of natural gas purchased from foreign countries and to make reliable and robust energy policies for the years ahead, it is crucial to make a reasonable and plausible prediction for natural gas consumption of Turkey. In this paper, we estimate the natural gas consumption using machine learning techniques on the basis of real monthly data representing natural gas consumption of Turkey between the years 2010 and 2018. The performances of machine learning techniques involving Artificial Neural Networks, Random Forest Tree, Regression, Time Series and Multiple Seasonality Time Series are compared in predicting the natural gas consumption of Turkey. Experimental results show that among the five techniques, artificial neural networks produce the best estimation, having the lowest mean square errors, followed by regression method. Time series shows the worst performance among all the techniques.
Evaluation Of Heavy Metal Content Of Salts Between Eskıkışla And Ocakbaşı (kırıkkale) Villages
(2021) Horasan, Bilgehan Yabgu; Öztürk, Alican
Salt, which is the main nutrient, is a very important raw material in the life of living organisms and industry. Salt production and consumption have improved and increased due to technological developments and industrialization. Salt has been used in the world and in our country since very ancient times. It is used in many fields, especially in the chemical industry, metallurgy, textile, medicine, and agriculture. In addition to sea, lake and spring salts, Turkey has very rich rock salt reserves. The Neogene aged Çankırı-Çorum Basin is one of the important basins where evaporitic formations are observed in the Central Anatolia region. Chemical analyses were carried out to determine the amount of heavy metal in salt samples taken from Oligocene aged units observed in the area between Ocabaşı and Eskikışla springs (Delice) in the Çankırı-Çorum basin. SEM-EDX, XRF and ICP-OES devices were used to determine the geochemical properties and quantities of heavy elements. According to the results of XRF, Na % ( 33.70-38.30), Cl %(52.10 - 57.70) SO3 %(0.75-1.93), Al2O3 %(0.90-1.93), CaO %(0.58- 2.69), MgO %(0.40-1.41) Fe2O3 % (0.18-0.64), SiO2 %(1.75-4.95), SrO, % (<0.010), BaO % (<0.010), Cr2O3 %(<0.010), K2O %(0.008-0.25), MnO %(<0.010) results are found. In the determination of heavy metals made with ICP-OES, it was determined that the heavy metals (Hg, As, Pb, Cd) published in the Turkish food codex salt communiqué were below the limit values.
Citation - Scopus: 9
Evaluation of Low-Velocity Impact Behavior of Epoxy Nanocomposite Laminates Modified With Sio2 Nanoparticles at Cryogenic Temperatures
(2019) Tatar, Ahmet Caner; Kaybal, Halil B.; Ulus, Hasan; Demir, Okan; Avcı, Ahmet
Epoxy based fiber reinforced composites are widely utilized in aerospace applications due to mechanical properties, thermal stability and, chemical resistance. However, it is known that materials become brittle and due to the poor crack resist restricts their applications in cryogenic engineering applications. The purpose of this paper is to experimentally investigate the cryogenic temperatures’ effect on the low-velocity impact (LVI) test of composite laminates. In addition, the effect of matrix modification in the studied composites was investigated. The LVI tests were conducted at RT (room temperature), 0 °C, -50 °C, -150 °C and -196 °C (liquid nitrogen temperature) on the composite laminates to measure influence on their energy absorption capacity. LVI tests performed according to ASTM-D-7136 standard under 10, 20 and 30 J impact energy levels. The results show that the contact forces and energy absorption capacities are improved by adding SiO2 nanoparticles into the epoxy matrix. The absorbed energy at cryogenic temperatures is increased by 24.87% from 18.1 J of pure epoxy resin to 22.7 J of modified epoxy. For the purpose of comparison, the LVI properties of composites at room temperature (RT) are also investigated. It is noted that the energy absorption capacity is not higher at cryogenic temperatures than that at RT for the modified and neat epoxy composites. Moreover, the peak contact forces are reduced in low-temperature conditions.
Examination of the Impact of Contemporary Additions on the Historical Building's Energy Performance
(Gazi Univ, 2024) Sayın, Selçuk; Öztürk, Büşra
Historical buildings are being destroyed over time and energy losses are increasing. Therefore, energy efficient preservation of historical buildings is an important issue. However, the application of contemporary additions has increased in cases such as the revival of building units that have not survived to the present day or when a new post-functional space is required. The aim of this study is to evaluate the impact of contemporary additions on the energy performance of historic buildings through a case study. For this purpose, energy simulation analyzes of the historical Süleyman Pasha Bath in Kocaeli province were performed through Design Builder. Before the simulations applied, information about stone, which is the original material of the building, and glass applied with contemporary materials were entered into the programme. The provinces of Izmir, Konya, Sivas, and Erzurum were selected from five climatic regions for the contemporary additional analysis. In these provinces there are many traditional bathing buildings with similar plan types. According to simulated results, it was concluded that the application of modern additions after the restoration negatively affected the energy performance in all five climate zones. Before applying contemporary additions to historical buildings, factors such as the microclimate, material properties and geometry of the building should be taken into consideration during the design phase and a decision should be made as a result of various analyses. Consequently, when contemporary additions to historic buildings are required, using the most effective construction techniques and materials is important in terms of building sustainability and effectiveness.
Citation - WoS: 7
Citation - Scopus: 10
Flash Sintering Effect on Fly Ash Microstructure
(Gazi Univ, Fac Engineering Architecture, 2022) Cetinkaya, Zeynep
In this study, densification of fly ash, (FA, industrial waste glass ceramic material) powder is carried out by electric field assisted flash sintering method. FA obtained from Tuncbilek Thermal Power Plant (Kutahya, Turkey). During the flash sintering experiment, 450 V/mm electric field is applied on sample with 0.85 amp current cutoff value. Flash sintering is accomplished in 70 sec at approximate to 1137 degrees C. According to XRD analysis, glassy phase, quartz, hematite, magnetite, magnesioferrite and mullite structures are in the structure. Based on the results of chemical analysis (XRF), reported in the literature, the sintering of ceramic materials formed by SiO2, Al2O3 and Fe2O3 individually or all together occurs at temperatures of 1500 degrees C and above. By electric field assisted flash sintering technique, the sintering temperature is decreased from 1500 to 1137 degrees C along with a decrement in sintering time from 3 hours to 70 seconds. The sintering process with this method was performed at a lower temperature and in a shorter time than traditional sintering methods. With the SEM micrographs, it has been proven that fly ash flash sintering processes have a denser structure compared to the conventional sintering.
Citation - WoS: 2
Citation - Scopus: 2
Gan/Zno Hybrid Nanostructures for Improved Photocatalytic Performance: One-Step Synthesis
(Scientific And Technological Research Council Turkey, 2023) Üstün, Tugay; Haspulat Taymaz, Bircan; Eskizeybek, Volkan; Kamış, Handan; Avcı, Ahmet
Nanostructured semiconductor materials are considered potential candidates for the degradation of textile wastewater via the photocatalytic process. This study aims to produce hexagonal gallium nitride (GaN) nanoplates and zinc oxide (ZnO) nanoparticles in a deionized water environment utilizing a one-step arc discharge process. Detailed characterization of samples has been completed via scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and UV visible spectroscopy methods. The hybrid nanostructure morphologies consist of nanoplates and nanorods of different sizes. The photoperformance of GaN/ZnO hybrid nanostructures was assessed via the malachite green (MG) dye degradation under UV exposure. Under UV exposure, the degradation yield reached 98% in 60 min. Compared to individual ZnO and GaN nanoparticles, the photocatalytic reaction rate of the GaN/ZnO photocatalyst is 2.2 and 3.6 times faster, respectively. Besides, the GaN/ZnO hybrid nanostructures show excellent photocatalytic stability. The energy consumption of the photocatalytic degradation in the presence of GaN/ZnO hybrid nanostructures was 1.688 kWhL-1. These results demonstrate that the GaN/ZnO hybrid nanostructures with improved photocatalytic activity are a reasonable option for the decomposition of textile wastewater under UV light exposure.
Gelişimsel Kalça Displazisi Ultrason Görüntülerinin İki Aşamalı Derin Öğrenme Yaklaşımı ile Kullanabilirlik Analizinin Yapılması
(Gazi Universitesi, 2025) Ceylan, Murat; Aydin, Bahattin Kerem; Çiftci, Sadettin; Özdemir, Cihad
Gelişimsel kalça displazisini tespit etmek için ana standart ultrasonik görüntülemedir. Ancak bu teknik operatöre ve dış faktörlere bağlıdır. Bu çalışmada değişkenliği ortadan kaldırmak ve hataları en aza indirmek için yapay zekâ tabanlı bir sistem geliştirilmiştir. Derin öğrenme modeli ilk olarak 3 temel anatomik yapının bulunduğu alanı segmentlere ayırır, daha sonra segmente edilen alanı özelliklerine göre sınıflandırarak 2 aşamalı bir derin öğrenme modeli oluşturur. 3 temel anatomik yapı segmente edildikten sonra ultrason görüntüsünün analiz edilebilirliği kontrol edilir. Ultrason görüntüsünün analiz edilebilirliğinin kontrolü için önce 3 temel anatomik yapının tespit edilip edilmediği kontrol edilmektedir. 3 temel anatomik yapı tespit edilmişse, iliak kemiğin taban çizgisine paralelliği kontrol edilerek US görüntüsünün analiz edilebilirliği kontrol edilmektedir. Geliştirilen sistemde toplam 840 görüntü kullanılmıştır. Sistem US görüntülerinin kullanılabilirliğini %96 doğrulukla karar verdiği gözlemlenmiştir. Geliştirilen sistemin gelişimsel kalça displazisi tanısında doğruluk ve hız açısından doktorlara yardımcı olacağı düşünülmektedir.

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