Scopus İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/395
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Article Citation - Scopus: 48Willingness to Pay for Renewable Electricity: A Contingent Valuation Study in Turkey(Elsevier Inc., 2019-12) Dogan, Eyup; Muhammad, IftikharRenewable energy sources are advised as an important alternative vehicle for dealing with a high rate of energy dependency and global warming. Turkey has also an ambitious national energy goal of minimizing energy import and producing 30% of electricity from renewable energy sources by 2023. However, it may not be easy to reach these goals. Willingness to Pay (WTP) thus plays a central role in directing appropriate policies for the country to realize its energy targets. This study reviews previous studies in the same literature as well as examines WTP of Turkish citizens for renewable electricity energy by using a stratified-sample and contingent valuation survey of 2500 households. The results from estimated models show that environmental conscience, membership to an environmental organization, age, education level, gender and income of households are significant determinants of WTP. In addition, the mean value of WTP for green electricity by Turkish households is estimated at around US$ 1 (with the exchange rate 5,3 TL/ US$) per month per household. A number of policy suggestions are further discussed. © 2023 Elsevier B.V., All rights reserved.Article Citation - WoS: 7Citation - Scopus: 11The Size and Concentration Effects of Al2O3 Nanoparticles on PSF Membranes With Enhanced Structural Stability and Filtration Performance(Desalination Publ, 2017-07) Saki, Seda; Uzal, Nigmet; Ates, NurayNanocomposite membranes have attracted attention for their high permeability, rejection efficiency, and thermal and mechanical stability. In this study, novel flat-sheet polysulfone nanocomposite membranes were prepared by a phase inversion method with polyethylenimine and Al2O3 nanoparticles to increase the flux and hydrophilicity. Al2O3 nanoparticles were added to the membrane matrix to enhance the permeability, selectivity, and mechanical resistance. Two different sizes of Al2O3 nanoparticles (20 and 80 nm) were used with different weight percentages of 0.2, 1, and 5 wt%. The effects of the size and concentration of the nanoparticles on the structural properties and filtration performance of the membranes were investigated. Scanning electron microscopy, Fourier transform infrared spectroscopy, porosity, water contact angle, thermogravimetric analysis, viscosity, and tensile strength measurements were used to characterize the prepared membranes. The membrane performance was evaluated with water flux and bovine serum albumin rejection tests. According to the results, the membrane containing 15 wt% polysulfone, 1 wt% polyethylenimine, and 5 wt% 20 nm Al2O3 showed the highest pure water flux, porosity, viscosity, and morphological stability. This membrane may have potential uses in water treatment applications.Article Citation - WoS: 2Citation - Scopus: 2The Nexus of Leadership, Political Empowerment, and Social Mobilization: The Case of the July 15 Coup Attempt in Turkey(Seta Foundation, 2020-06-30) Donmez, Rasim Ozgur; Timur, Kasim; Lloyd, Fatma Armagan TekeThis study analyzes the mutually empowering relations between Turkish President Recep Tayyip Erdogan and his followers, and how Erdogan's charismatic leadership and image functioned to galvanize his followers on the night of July 15, 2016, when large numbers of them mobilized against the attempted coup. The article has three sections. The first is a theoretical discussion which sheds light on the concept and the underlying mechanisms of political empowerment and its effects on the relationships between leaders and followers. The second section evaluates Erdogan's characteristics and ruling style, which was instrumental in motivating resistance to the abortive coup. Finally, the third section analyzes the various means by which Erdogan was able to inspire the masses to mobilize against the armed junta through interviews and observations.Article Citation - WoS: 2Citation - Scopus: 2Structural Profile Matrices for Predicting Structural Properties of Proteins(World Scientific Publ Co Pte Ltd, 2020-07-10) Azginoglu, Nuh; Aydin, Zafer; Celik, MetePredicting structural properties of proteins plays a key role in predicting the 3D structure of proteins. In this study, new structural profile matrices (SPM) are developed for protein secondary structure, solvent accessibility and torsion angle class predictions, which could be used as input to 3D prediction algorithms. The structural templates employed in computing SPMs are detected by eight alignment methods in LOMETS server, gap affine alignment method, ScanProsite, PfamScan, and HHblits. The contribution of each template is weighted by its similarity to target, which is assessed by several sequence alignment scores. For comparison, the SPMs are also computed using Homolpro, which uses BLAST for target template alignments and does not assign weights to templates. Incorporating the SPMs into DSPRED classifier, the prediction accuracy improves significantly as demonstrated by cross-validation experiments on two difficult benchmarks. The most accurate predictions are obtained using the SPMs derived by threading methods in LOMETS server. On the other hand, the computational cost of computing these SPMs was the highest.Article Citation - WoS: 1Citation - Scopus: 1Simultaneous Low Noise Radio Frequency Tone and Narrow Linewidth Optical Comb Generation From a Regeneratively Mode-Locked Laser(SPIE - Society of Photo-Optical Instrumentation Engineers, 2014-10-29) Ozdur, Ibrahim; Ozharar, Sarper; Delfyett, Peter J.A regeneratively mode-locked laser with simultaneous low noise radio frequency (RF) tone and optical comb generation is presented. The laser does not need any external RF signal and emits a pulse train at similar to 10 GHz repetition rate with a 1.5-ps optical pulse width after compression. The generated RF tone has a signal-to-noise ratio of 121 dB/Hz and an RF fluctuation of 10(-9) over 0.1 s. The optical frequency comb spacing is also at similar to 10 GHz and the optical comb tooth has a linewidth of <1 kHz. (C) 2014 Society of Photo-Optical Instrumentation Engineers (SPIE)Article Citation - WoS: 7Citation - Scopus: 9Robust Tracking Controller for SEPIC Drivers(Inst Engineering Technology-IET, 2016-11) Ablay, G.The non-minimum phase, non-linear nature of the SEPIC (single-ended primary inductor converter) makes it very difficult to get robust operating conditions under load variations. Sliding-mode control method is utilised to design a robust controller for tracking control of SEPIC converters for various applications. The implementation of the method is illustrated with the use pulse-width modulation comparators in the control loop to preclude the risk of modulator saturation and to ease the operations. The performance of the SEPIC converter is investigated through numerical simulation and analogue electronics implementation to show the validity, robustness and feasibility of the proposed controller.Article Citation - WoS: 34Citation - Scopus: 41Revisiting the Relationship Between Natural Gas Consumption and Economic Growth in Turkey(Taylor & Francis inc, 2015-01-12) Dogan, E.The objective of this study is to re-analyze the relationship between natural gas consumption (NGC) and economic growth (GR) for Turkey in a multivariate framework by including capital and labor as additional variables because several papers suggest that a bivariate model can suffer from omitted-variables bias. As compared to the findings of Isik (2010), who previously investigated the short-and long-run relationships between GR and NGC using a bivariate model, we find that the magnitude of the coefficient estimate of NGC become substantially smaller in the long-run and the sign of short-run estimate of NGC shift to negative after accounting for capital and labor as well. In addition to that covered by Isik (2010), we investigate the direction of causality between GR and NGC using the vector error correction model Granger causality approach, and reveal the evidence of feedback hypothesis for Turkey.Article Citation - WoS: 6Citation - Scopus: 8Removal of Heavy Metals from Wastewater Solution Using a Mechanically Activated Novel Zeolitic Material(Pleiades Publishing Ltd, 2020-11) Uckun, Sukru; Sarikaya, Musa; Top, Soner; Timur, Irfan; Şükrü, Uçkun; Musa, Sarıkaya; Soner, Top; İrfan, TimürThe removal of heavy metals from the wastewater solution using a novel zeolitic material was conceived and experimentally probed. The natural zeolite was ground in a planetary ball mill to increase negative surface charge and amorphization of the material as well as a conventional ball mill. The ground materials were used for the removal of heavy metals from the wastewater solution. The maximum removals were found to be 78% for Pb, 67% for Ni and 54% for Cd by using the conventional milled natural zeolitic material at pH 11. However, 93% of Pb, 72% of Ni and 57% of Cd were removed at pH 9 with the novel zeolitic material milled by a planetary ball mill. It was revealed that the novel zeolitic material produced by a planetary ball mill increased the absorption capacity of the heavy metals and reduced the alkali requirement for pH adjustment. The removal order of heavy metals with the novel zeolitic material is determined as follows: Pb> Ni>Cd.Article Citation - WoS: 4Citation - Scopus: 4Rec. 2100 Color Gamut Revelation Using Spectrally Ultranarrow Emitters(SPIE - Society of Photo-Optical Instrumentation Engineers, 2017-11-22) Genc, Sinan; Uguz, Mustafa; Yilmaz, Osman; Mutlugun, EvrenWe theoretically simulate the performance of ultranarrow emitters for the first time to achieve record high coverage for the International Telecommunication Union Radiocommunication Sector BT. 2100 (Rec. 2100) and National Television System Committee (NTSC) color gamut. Our results, employing more than 130-m parameter sets, include the investigation into peak emission wavelength and full width at half maximum (FWHM) values for three primaries that show ultranarrow emitters, i.e., nanoplatelets are potentially promising materials to fully cover the Rec. 2100 color gamut. Using ultranarrow emitters having FWHM as low as 6 nm can provide the ability to attain 99.7% coverage area of the Rec. 2100 color gamut as well as increasing the NTSC triangle to 133.7% with full coverage. The parameter set that provides possibility to fully reach Rec. 2100 also has been shown to match with D65 white light by making use of the correct combination of those three primaries. Furthermore, we investigate the effect of the fourth color component on the CIE 1931 color space without sacrificing the achieved coverage percentages. The investigation into the fourth color component, cyan, is shown for the first time to enhance the Rec. 2100 gamut area to 127.7% with 99.9% coverage. The fourth color component also provides an NTSC coverage ratio of 171.5%. The investigation into the potential of emitters with ultranarrow emission bandwidth holds great promise for future display applications. (C) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)Article Citation - WoS: 17Citation - Scopus: 24Recovery of Caustic From Mercerizing Wastewaters of a Denim Textile Mill(desalination Publ, 2015-03) Varol, Cihangir; Uzal, Nigmet; Dilek, Filiz B.; Kitis, Mehmet; Yetis, UlkuThe objective of this study was to evaluate caustic recovery from mercerizing wastewater originating from a denim textile producing plant using membrane technology. For this purpose, ultrafiltration (UF) and nanofiltration (NF) processes were considered. In the first stage, in an attempt to control the possible membrane fouling, pretreatment alternatives of flocculation, centrifugation, and microfiltration were evaluated. These pretreatment application alternatives were unsuccessful as they did not provide considerable color and solids removal. In the second stage, UF and NF processes were tested using a tight UF membrane (GR95PP, Alfalaval) and three NF membranes (NP010 and NP030, Microdyn Nadir, and MPF34, Koch Membranes) to accomplish the caustic recovery without applying any pretreatment. The best performance was obtained with NP010 NF in terms of permeate flux along with color and COD rejections. Then, for this membrane the effects of transmembrane pressure (4.03 and 6.23 bar), cross-flow velocity (from 0.40 to 1.40 m/s), and feed temperature (20 and 40 degrees C) were investigated. Temperature positively affected the permeate flux without significant loss in recovery and rejections. Caustic stream produced had about 98-100% of NaOH in the feed at a concentration of 30-40 g/L and therefore was recyclable after a concentration process.
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