Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collections

Permanent URI for this collectionhttps://hdl.handle.net/20.500.13091/3

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Usability of Turkish National Gnss Permanent Network-Active Points for Detecting Deformations
(IEEE, 2018) Gündüz, Ahmet Mete; İnal, Cevat; Yıldırım, Ömer
Measurement and analyzing of deformations are one of the important subjects of geodesy. The effects of possible damages can be decreased by determining the deformations on earth crust and engineering structures. Both to lower the operating expenditure and to be assumed that there is no deformation during the measurement period, deformation measurements should be performed in a short time. At the present time, GNSS technique is used commonly to determine the deformations. In this study, it was investigated the usability of the Turkish National GNSS Permanent Network-Active (TNGPN-Active) points to determine the deformations. For this purpose, a pillar was established on the garden of Kutahya Environment and Urban Ministry Provincial Directorate. A mechanism which is for creating virtual deformation on the pillar was produced in high accuracy by using CNC machining center. The GNSS receiver was placed on the levelled mechanism and shifted with 1 cm interval along 20 cm on East-West, North-South and vertical directions. The GNSS measurements which were collected for 24 hours on the mechanism were adjusted based on the TNGPN-Active points which names are HARC, BILE, KUTA, ESKS, EMR1, AFYN, USAK, DEIR by using Bernese v5.2 Scientific GNSS software. The GNSS data which were collected were separated 6, 12 and 24 hourly parts while it was being processed. For any situations, cartesian coordinates of the points (X, Y, Z) and their root mean square errors (rmse) were calculated. The deformation analyses were performed for each situation by using the cartesian coordinates and the rmse. At the end of the analyses; it was reached the consequences that by using 12 and 24 hourly data which have 30 seconds data record interval is able to determine for 1 cm deformation on horizontal direction, by using 24 hourly data is able to determine for 1 cm deformation on vertical direction. In addition, the cartesian coordinates were transformed to projection coordinates for the purpose of comparing the shifting amount with the value which was calculated with measurements, the amount which was calculated from coordinates had been compared with the amount which was given as virtualy. At the end of the comparing, it was seen that when the measurement time increases, the virtual shifting amounts and the calculated values get closer to each others.
Citation - WoS: 19
Citation - Scopus: 20
Self-Catalyzing Pyrolysis of Olive Pomace
(ELSEVIER, 2018) Dinç, Gamze; Yel, Esra
In this study, catalytic effect of intrinsic inorganics was evaluated by comparing pyrolysis end products obtained from pyrolysis of olive pomace (OP) in three different initial weights (30,100 and 200 g). Pyrolysis of OP with higher weights led to self-catalyzing pyrolysis resulting in approximately 20% bio-oil quantity increment when pyrolyzed OP weight increased from 30 g to 200 g. Additionally, both intrinsic inorganic percentages remained in pyrolysis chars and organic compounds in pyrolysis liquids altered with pyrolyzed OP weights. While the lowest inorganic percentage in chars was found at the pyrolysis of the highest OP weight, the highest belonged to 30 g OP pyrolysis. Moreover, while oxygenated compounds, namely aldehydes and ketones, in pyrolysis bio-oil decreased explicitly at 200 g OP pyrolysis, variety in alkane and alkene compounds enhanced at higher weights OP pyrolysis. Finally, the effects of temperature, heating rate and retention time on pyrolysis products were evaluated. Results showed that liquid products increased at 5 degrees C/min heating rate and decreased at 1 degrees C/min heating rate as pyrolysis temperature increased from 450 to 600 degrees C in the pyrolysis without retention time. However, reverse tendency was observed in liquid product quantities in the case of pyrolysis with retention time. Furthermore, while effect of temperature increment on pyrolysis gas and liquid was mostly opposite to each other in all pyrolysis conditions, bio-chars' quantity irregularly altered as to pyrolysis conditions.
Citation - WoS: 9
Citation - Scopus: 11
Adrenal Tumor Segmentation Method for Mr Images
(ELSEVIER IRELAND LTD, 2018) Barstuğan, Mücahid; Ceylan, Rahime; Asoğlu, Semih; Cebeci, Hakan; Koplay, Mustafa
Background and objective: Adrenal tumors, which occur on adrenal glands, are incidentally determined. The liver, spleen, spinal cord, and kidney surround the adrenal glands. Therefore, tumors on the adrenal glands can be adherent to other organs. This is a problem in adrenal tumor segmentation. In addition, low contrast, non-standardized shape and size, homogeneity, and heterogeneity of the tumors are considered as problems in segmentation. Methods: This study proposes a computer-aided diagnosis (CAD) system to segment adrenal tumors by eliminating the above problems. The proposed hybrid method incorporates many image processing methods, which include active contour, adaptive thresholding, contrast limited adaptive histogram equalization (CLAHE), image erosion, and region growing. Results: The performance of the proposed method was assessed on 113 Magnetic Resonance (MR) images using seven metrics: sensitivity, specificity, accuracy, precision, Dice Coefficient, Jaccard Rate, and structural similarity index (SSIM). The proposed method eliminates some of the discussed problems with success rates of 74.84%, 99.99%, 99.84%, 93.49%, 82.09%, 71.24%, 99.48% for the metrics, respectively. Conclusions: This study presents a new method for adrenal tumor segmentation, and avoids some of the problems preventing accurate segmentation, especially for cyst-based tumors. (C) 2018 Elsevier B.V. All rights reserved.
Citation - WoS: 2
Citation - Scopus: 5
Performance Analysis of Image Mosaicing Methods for Unmanned Aerial Vehicles
(IEEE, 2018) Tahtırvancı, Aykut; Durdu, Akif
Today, Unmanned Aerial Vehicles (UAVs) have gained considerable importance, especially in the defense industry. Thanks to the cameras placed on these vehicles, a certain area can be explored for safety reasons. Various image processing techniques are used for this. Image mosaicing is one of these techniques. In this study, the effects of SIFT(Scale-Invariant Feature Transform), SURF(Speeded Up Robust Features), FAST(Features from Accelerated Segment Test) and Harris corner detector methods used for image mosaicing on images taken from unmanned aerial vehicles are tested and compared.
Citation - WoS: 8
Citation - Scopus: 9
Serbest Yüzey ve Bir Küre Art İzi Arasındaki Etkileşimlerin Araştırılması
(2018) Doğan, Sercan; Özgören, Muammer; Okbaz, Abdulkerim; Şahin, Beşir; Akıllı, Hüseyin
Bu çalışma, küre çapına göre tarif edilen Reynolds sayısının 2,5x103 ve 1x104 aralığında farklı daldırma yükseklikleri için açık bir su kanalında serbest su yüzeyi ve kürenin art izi bölgesi arasındaki akış yapısı etkileşimini sunmaktadır. Anlık ve zaman ortalaması alınmış hız alanı, akım çizgisi topolojisi, girdaplar ve hız konturları gibi akış modellerini göstermek için Parçacık Görüntülemeli Hız ölçme (PIV) ve boya görselleştirme teknikleri uygulanmıştır. Küre, serbest yüzeye kısmen daldırılma konumundan serbest yüzeyden iki küre çapı kadar aşağı doğru çeşitli daldırma konumlarına 0,25? h/D ?3,0 aralığında sabitlenmiştir. Daldırma oranı, küre alt kolunun serbest yüzey ile olan mesafesinin küre çapına oranı olarak tanımlanmıştır. Kürenin yerleştirildiği konumlara bağlı olarak, art izi bölgesinin özellikleri üç farklı akış olayı sergilemiştir. Bunlar; daldırma oranı 0,25? h/D ?1,0 aralığı için üniform akış bölgesi ve serbest yüzey arasındaki kısıtlı bir art izi bölgesi, daldırma oranı 1,25? h/D ?2,0 aralığı için serbest yüzey etkisinden dolayı simetrik olmayan akış modelleri ve daldırma oranı 2,5? h/D ?3,0 aralığı için simetrik akış yapıları olarak sınıflandırılmıştır. Akış fiziği açısından bahsedilen akış yapıları için daha detaylı sonuçlar karşılaştırılmalı olarak sunulmuş ve yorumlanmıştır.
Citation - Scopus: 2
Fatigue Fracture Behaviour of Asymmetric Spur Gear Tooth Under Cyclic Loading
(ELSEVIER SCIENCE BV, 2018) Demet, Seyit Mehmet; Ersoyoğlu, Ali Serhat
When the research on the gears are investigated, it is seen that there are different studies on the design and analysis. In the majority of research studies, the tooth root curve is designed as a trochoid curve as a results of production method. According to literature, application of the circular fillet method instead of the trochoid curve in the tooth root would increase the strength of the tooth root. Fatigue life will also be positively affected with increase of tooth strength. Because the less stress will develop in the tooth root, the fatigue life of the gear tooth will increase. In this study, we have designed and manufactured involute profile asymmetric spur gears using the circular fillet method in tooth root region. Involute profile asymmetric gears tooth have lower contact stress and superior tooth root strength than symmetric gears tooth. In this work, fatigue damages on asymmetric gear tooth caused by cyclic loads and effects of material hardness on fatigue life of gear tooth were investigated. In the extent of the study, a new single-tooth bending fatigue test apparatus (STBFT) was developed to investigate the fatigue performance of the gears. Low-cycle and high-cycle tests were done to detect the fatigue performance of the asymmetric gears. (C) 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers.
Citation - WoS: 134
Citation - Scopus: 167
A New Hybrid Ant Colony Optimization Algorithm for Solving the No-Wait Flow Shop Scheduling Problems
(ELSEVIER SCIENCE BV, 2018) Engin, Orhan; Güçlü, Abdullah
This paper proposes an effective new hybrid ant colony algorithm based on crossover and mutation mechanism for no-wait flow shop scheduling with the criterion to minimize the maximum completion time. The no-wait flow shop is known as a typical NP-hard combinational optimization problem. The hybrid ant colony algorithm is applied to the 192 benchmark instances from literature in order to minimize makespan. The performance of the proposed Hybrid Ant Colony algorithm is compared to the Adaptive Learning Approach and Genetic Heuristic algorithm which are used in previous studies to solve the same set of benchmark problems. The computational experiments show that the proposed Hybrid Ant Colony algorithm provides better results relative to the other algorithms. (C) 2018 Elsevier B.V. All rights reserved.
Citation - WoS: 2
Citation - Scopus: 2
Modeling and Optimization of Hexavalent Chromium Sorption Onto Amberjet 1200h by Using Multiple-Linear Regression
(IEEE, 2018) Tümer, Abdullah Erdal; Edebali, Serpil
In this study, multiple-linear regression (MLR) model was used to predict the efficiency of two commercial resins, Amberjet 1200H and Diaion CR11, used for the removal of Cr (III) from aqueous solutions. The effects of descriptors used in the experiments (pH, amount of resin, temperature, contact time and concentration) on the removal were investigated with 36 different laboratory studies. The removal efficiency was calculated. Two regression models were developed with MLR analysis which is used to describe the effects of experiment parameters. The performances of both models developed to determine the removal efficiency of these sorption systems were found satisfactory. Statistical results indicated that Amberjet 1200H was more effective than Diaion CR11 for the removal of Cr(III).
Image Processing Based Task Allocation for Autonomous Multi Rotor Unmanned Aerial Vehicles
(SCIENCE & INFORMATION SAI ORGANIZATION LTD, 2018) Durdu, Akif; Ergene, Mehmet Celalettin; Demircan, Onur; Uğuz, Hasan; Mahmutoglu, Mustafa; Kurnaz, Ender
Nowadays studies based on unmanned aerial vehicles draws attention. Especially image processing based tasks are quite important. In this study, several tasks were performed based on the autonomous flight, image processing and load drop capabilities of the Unmanned Aerial Vehicle (UAV). Two main tasks were tested with an autonomous UAV, and the performance of the whole system was measured according to the duration and the methods of the image processing. In the first mission, the UAV flew over a 4x4 sized color matrix. 16 tiles of the matrix had three main colors, and the pattern was changed three times. The UAV was sent to the matrix, recognized 48 colors of the matrix and returned to the launch position autonomously. The second mission was to test load drop and image processing abilities of the UAV. In this mission, the UAV flew over the matrix, read the pattern and went to the parachute drop area. After that, the load was dropped according to the recognized pattern by the UAV and then came back to the launch position.
Mycobacterium Avium Subsp. Paratuberculosis’in Süt ve Süt Ürünlerinde Tespit Yöntemleri
(2018) Telli, Nihat; Sayar, Ahmet Güner
Mycobacterium avium kompleksi üyelerinden olan Mycobacterium avium subsp. paratuberculosis (MAP) çok çeşitli hayvan türlerinde Johne hastalığının (paratüberkülozis) etiyolojik etkenidir. Paratüberkülozun klinik belirtilerini gösteren ve asemptomatik taşıyıcı hayvanlar etkeni süt, dışkı ve spermleriyle yaymaktadırlar. Süt direkt olarak etkeni taşıyabildiği gibi özellikle dışkı kaynaklı indirekt bulaşmalar da gerçekleşebilmektedir. Sütün yanı sıra peynir, yoğurt, krema, tereyağı, dondurma vb. süt ürünleri de etkeni taşıyabilmektedir. Süt sığırlarındaki Johne hastalığı ile insanlarda görülen Crohn hastalığı insidenslerinde dünya genelinde artış görülmektedir. Yüksek klinik ve patolojik benzerlikler bulunan bu hastalıklar arasındaki olası ilişkide gıdaların rolünün yorumlanmasında ve güvenilir sonuçlar alınmasında MAP’ın süt ve süt ürünlerinde tespit yöntemleri önem arz etmektedir. Bu amaçla süt ve süt ürünlerinde Ziehl-Neelsen boyama, floresan mikroskop, katı faz sitometri ve biyolüminesans gibi direkt tanı ve kültür yöntemleri ile MAP etkenleri araştırılabilmektedir. Bu yöntemlerin yanı sıra radyoimmün testler (RIA), enzim bağlı immün testler (ELISA), agar jel immünodifüzyon testi (AGID) ve komplement fiksasyon testi (CF test) gibi serolojik teknikler ve polimeraz zincir reaksiyonu (PCR), nükleik asit hibridizasyonu, immunomagnetic separation PCR, Nested PCR, Real-Time PCR gibi moleküler teknikler veya bu tekniklerin kombinasyonlarıyla hızlı tanı yöntemleri geliştirilmiştir.
Citation - WoS: 1
Citation - Scopus: 1
A New Aluminum Alloy Cable Cleat Design and Development a Smart Cable Protection System
(IEEE, 2018) Çetinkaya, Nurettin
One of the most important materials of electrical power systems is the power cable. Power cables during a short circuit and in normal operation carry high currents. Especially short-circuit currents apply electromechanical forces to the power cables. So they must be fixed along the cable routing. For fixing, cable cleats are used in many different types. The cable cleat designed in this study is different from the cable cleat previously developed for reducing the influence of electromagnetic forces. A new connection is also proposed in this work for measuring short-circuits fault currents. In addition to the mechanical forces that occur during short circuit faults, in the areas where cable cleats are regional warming occurs. In this study a new design was developed in order to prevent this situation. Operators always require that at least thermal losses. This new design, which minimizes thermal losses, also fulfills the other requirements of the IEC 61914:2016 standard. In addition this study describes how to calculate the forces between cables in the event of short-circuit, including the relationship between cable cleat spacing and cable spacing. A test assembly is designed for the testing of the cable cleats. The details of the short-circuit test are described. The adequate data is provided to select an appropriate cable cleats and specify to distance between fixing for given cable spacing and short-circuit current. A correctly rated cable cleat, especially properly specified and installed, is capable of withstanding the electromechanical forces in the event of various short circuit faults. Finally, this paper presents new cable cleat design, new protection system, test data, cable cleat standard, and other practice.
Citation - WoS: 14
Citation - Scopus: 21
Design and Simulation of the Hierarchical Tree Topology Based Wireless Drone Networks
(IEEE, 2018) Çeltek, Seyit Alperen; Durdu, Akif; Kurnaz, Ender
In drone applications, the drone could send data using telemetry devices or radio frequency module which has a limited range. So, there is no interaction between user and drone after a certain range. In this study, a hierarchical tree topology based wireless drone network is designed and presented to overcome range challenge. Proposed network consist of three main parts; Control Center (CC), Master Drone (MD) and Slave Drones (SDs). The CC as a network manager communicates with just MD via telemetry devices. SDs are explorer drones for the search and rescue application. The data transfer between CC and SDs is provided by MD which is explorer like SDs. This paper clearly shows that the enhancement of the communication range is possible with such this approach. Also the designed drone networks are simulated using V-REP (Virtual Robot Experimentation Platform). According to the simulation results, the proposed drone network system operates quickly, and finds the target in 5 minutes, which classical system not find in 10 minutes. The proposed model clearly shows that an application using a drone is completed in a shorter time with the drone swarm well organized.
Citation - WoS: 36
Citation - Scopus: 42
Removal of Pahs From Leachate Using a Combination of Chemical Precipitation and Fenton and Ozone Oxidation
(IWA PUBLISHING, 2018) Ateş, Havva; Argun, Mehmet Emin
In this study, six emerging pollutants, belonging to the polycyclic aromatic hydrocarbons (PAHs) group, found in landfill leachate were investigated for their removal by sequential treatment processes including chemical precipitation (CP), Fenton oxidation (FO) and ozone oxidation (OO). Each treatment process was run under different conditions using an experimental design program. Optimization of both CP and FO processes was designed based on the measured values of the residual chemical oxygen demand (COD) of the samples analyzed. The analysis of variance test was applied to the obtained results for determination of statistical significance of the model. Removal efficiencies of micropollutants were determined in the optimal conditions both for CP and FO processes. Samples obtained after these processes were treated with different pH and ozonation times for observing the performances of ozonation on micropollutant removal under different operating conditions. In this study, the removal of acenaphthylene, acenaphthene, fluorene, phenanthrene, fluoranthene and pyrene micropollutants was investigated. The values obtained for PAHs in leachate were determined to be above 10 ppb. In the CP process, the removal efficiencies for PAHs were ranged between 6% and 40% except for pyrene. Removal efficiencies of all micropollutants with FO were over 70% except for fluorene (55%). The removal efficiencies of the investigated micropollutants were 80-100% as a result of consecutive treatment processes including CP, FO and OO respectively.
Citation - WoS: 6
Citation - Scopus: 6
Statistical Optimization of Ettringite Precipitation in Landfill Leachate
(BRAZILIAN SOC CHEMICAL ENG, 2018) Aygün, Ahmet; Doğan, Selim; Argun, Mehmet Emin
In the present study, experiments were conducted to optimize sulfate removal efficiency with ettringite precipitation from landfill leachate using Response Surface Methodology (RSM) and Central Composite Design (CCD). The statistical analysis of the results showed that the operating parameters such as molar rates of Ca/SO4 and Al/SO4, and pH had a significant effect on sulfate removal efficiency. Aluminum hydroxide and calcium hydroxide were used for external sources of aluminum and calcium. The goodness of the model was checked by different criteria including the coefficient of determination (R-2 = 0.94), p value (<0.0001), adequate precision (14.78), and coefficient of variance (7.30). The RSM results indicated that the fitted model could be appropriate to predict sulfate removal efficiency. A 55.7% maximum sulfate removal efficiency was obtained at pH 11.95 for 2.29 Ca/SO4 and 0.74 Al/SO4 molar ratios. Sulfate inhibition effects on treatment methods such as the anaerobic process decreased with increasing COD/SO4 ratio from 14:1 to 25:1 by ettringite precipitation.
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.
Assessment of Work Accidents in Highway, Street and Bridge Construction
(International Multidisciplinary Scientific Geoconference, 2018) Bilim, Atiye; Çelik, Osman Nuri
Occupational health and safety is an important work discipline that must be included in the working life. Especially, developed countries have been able to place this discipline in working life, while developing countries have still problems. These problems take place both in terms of legislation and practice. The situation is similar to that of developing countries, in Turkey. The construction sector is in line with the development status of a country. The construction sector contributes both directly and indirectly to the country's economy. It has become indispensable for the economy of a country with its share in employment and it stimulates production of goods and services related to the sector. The construction sector is not just about building constructions. We also need bridges, metros and high-speed train lines. Transports have a major contributor to the development of a country. In parallel with technological developments, large investments related with transports become increase. Due to the revival in this sub-sector, the number of work accidents has also tended to increase. Therefore, the work accidents in the highway, street and bridge constructions, which are the sub-activities of the construction sector, must be examined. In this study, work accidents in the sector were analyzed for Turkey and U.S. Also, the share of the sector in total work accidents and construction accidents were determined for Turkey and U.S. The causes of fatal work accidents in highway, street and bridge constructions were mentioned. © 2018, International Multidisciplinary Scientific Geoconference. All rights reserved.
Citation - Scopus: 1
Full-Automatic Liver Segmentation on Abdominal Mr Images
(IEEE, 2018) Barstuğan, Mücahid; Ceylan, Rahime; Asoğlu, Semih; Cebeci, Hakan; Koplay, Mustafa
Liver segmentation process is a challenging field in computer-aided medical image analysis. This study implemented liver segmentation on Abdominal MR images. The liver was automatically segmented from images by morphological methods with high performance. Liver segmentation process was implemented on 56 MR images and the segmentation results were examined. In this study, an effective and fast method was proposed. Seven evaluation metrics (sensitivity, specificity, accuracy, precision, Dice coefficient, Jaccard rate, Structural Similarity Index (SSIM)) were used to test the performance of the proposed method. Mean Dice coefficient value was obtained as 91.701%, mean Jaccard rate value was obtained as 85.052% on 56 images. Segmentation duration for an image (T1 and T2 phases) was found as 2.828 seconds with the proposed method.
Citation - WoS: 44
Citation - Scopus: 45
Uv/Visible Light Active Cucro2 Nanoparticle-Sno2 Nanofiber P-N Heterostructured Photocatalysts for Photocatalytic Applications
(ROYAL SOC CHEMISTRY, 2018) Dursun, Sami; Kaya, İsmail Cihan; Kalem, Volkan; Akyıldız, Hasan
CuCrO2 nanoparticle decorated SnO2 nanofiber composites have been prepared as novel p-n heterostructured semiconductor photocatalysts for the degradation of organic pollutants in wastewater. The composite structure was achieved via drop casting of various amounts of hydrothermally derived CuCrO2 nanoparticles on electrospun SnO2 nanofibers. The microstructural and morphological features of each semiconductor and the formation of p-n heterojunctions between them were characterized. In addition, the photo-response and electrochemical properties of the samples were determined. The photocatalytic activity of the heterostructured photocatalysts was investigated systematically as a function of the amount of CuCrO2 nanoparticles in the samples. Experimental results showed that the optimal decoration amount was 0.6 wt% CuCrO2 on SnO2. This composite photocatalyst displayed a 41% higher rate constant value compared to pure SnO2 nanofibers in the degradation of methylene blue dye molecules and reached 83% degradation under UV/visible light irradiation after 1 h. The increase in the photocatalytic activity was ascribed to the incorporation of Cr3+ and Cu+ cations into the SnO2 host lattice and the more effective electron-hole pair separation in the heterostructured sample. The presented data here are highly convincing in comparison to those of UV active p-n heterostructured photocatalysts reported previously in the literature. Therefore, this work opens the way to develop visible light active p-n heterostructured semiconductor photocatalysts using p-type delafossites with n-type oxides.
Citation - WoS: 3
Citation - Scopus: 8
Mitigation of Voltage Unbalance in Microgrids Using Thermostatically Controlled Loads
(IEEE, 2018) Çimen, Halil; Çetinkaya, Nurettin
With the development of technology, some important developments occur in electrical energy systems. Especially smart grids and micro grids will be an important part of energy systems in the following years. With the increasing use of micro grids, more renewable power plants will be included in the system. However, the production of renewable energy sources varies according to the weather conditions. Therefore, the generated energy is not known beforehand. Increasing single-phase loads (such as electric vehicle charging stations), unpredictable renewable generation and uncertainty of consumption can lead to problems of voltage unbalance in the micro grid. This problem can damage the network in many ways. In this study, the problem of voltage unbalance occurring in the microgrid was tried to be reduced by demand side management. The comfort of the customer should not be affected when demand side management is performed. For this reason, the most suitable load for demand side management is thermostatically controlled loads (TCL). An algorithm has been proposed to reduce voltage unbalance by using these loads. This algorithm was tested with the help of PSCAD/EMTDC program.
Citation - WoS: 38
Citation - Scopus: 42
Photocatalytic Activity and Dielectric Properties of Hydrothermally Derived Tetragonal Batio3 Nanoparticles Using Tio2 Nanofibers
(ELSEVIER SCIENCE SA, 2018) Küçük, Öznur; Teber, Seda; Kaya, İsmail Cihan; Akyıldız, Hasan; Kalem, Volkan
Tetragonal BaTiO3 nanoparticles have been hydrothermally synthesized using the electrospun TiO2 nanofibers as the Ti-source. Microstructural and compositional analyses have been carried out using XRD, SEM, TEM, XPS, and Raman spectroscopy. Characterization studies confirmed that the BaTiO3 nanoparticles had a tetragonal structure with an average particle size of 100 nm. Photocatalytic activities of the nanoparticles were investigated via the decolorization of methylene blue dye aqueous solutions under visible light and UV-A irradiations. The degradation efficiency reached to 13 and 35% after exposing to light for 60 min with visible and UV-sources, respectively. Effect of sintering temperatures on the dielectric properties was also investigated. Among all the sintering temperatures employed, 1473 K was the optimum sintering temperature for these ceramics in terms of high relative density (95.3%), high dielectric constant (3162 at 1 MHz), and low loss tangent (15 x 10(-3) at 1 MHz). Experimental results showed that electrospun TiO2 fibers can be used as a precursor template to produce nano-scale BaTiO3 particles which are suitable for various applications such as photocatalysis and capacitors. (C) 2018 Elsevier B.V. All rights reserved.

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