Sürdürülebilir Kalkınma Amaçları
Yazarlar
- Dertli, Enes(24)
- Cuce, Erdem(18)
- İspirli, Hümeyra(14)
- Cuce, Pinar Mert(13)
- Alım, Bünyamin(12)
- Mercan, Emin(12)
- Sert, Durmuş(12)
- Şenay, Volkan(12)
- Tozlu, Alperen(11)
- Artar, Musa(10)
- Korkmaz, Şadan(10)
- Pat, Suat(10)
- Yilmaz, Mustafa Tahsin(10)
- Özen, Soner(10)
- Gökçe, H.S.(9)
- Sagdic, Osman(9)
- Şakar, Erdem(9)
- Bayram, Ozkan(8)
- Demirtas, M.(8)
- Purcek, G.(8)
- Ergün, Mustafa(7)
- Yanar, H.(7)
- Demir, Lütfü(6)
- Taylan, Osman(6)
- Abdioglu, M.(5)
- Abdioglu, Murat(5)
- Alim, Bünyamin(5)
- Carbas, Serdar(5)
- Guclu, Tamer(5)
- Gökçe, H. Süleyman(5)
- Sayyed, M.I.(5)
- Han, İbrahim(4)
- Ozturk, K.(4)
- Zhang, Z.F.(4)
- Zhang, Z.J.(4)
- Özahi, Emrah(4)
- Şahin, Engin(4)
- Abusoglu, Aysegul(3)
- Andiç-Çakır, Özge(3)
- Baltakesmez, Ali(3)
Yayınlar
- MakaleAçık Erişim2015Scopus SJRQ2Investigation of Comet Wild-2 in terms of effective atomic numbers
Han, Ibrahim; Ün, Adem; Alimb, Bünyamin
Effective atomic numbers (Z eff ) and effective electron densities (N el ) of 69 samples collected from Comet Wild-2 within scope of Stardust mission were determined in the energy range from 1 keV to 100 GeV. The data were individually evaluated for Wild-2 olivines, pyroxene, FeANi sulfide and silicate glass samples to obtain remarkable information about Comet Wild-2. The photon energy and sample composition dependencies of obtained data were investigated. The results show that Z eff and Nel values depend strongly on chemical composition and interaction photon energy. The result of present study may be providing new and helpful knowledge about the Comet Wild-2 and ourSolar System.
AtıfScopus6WoS6OpenAlex7
İncele - MakaleAçık Erişim2015Scopus SJRQ1Levitation and guidance force efficiencies of bulk YBCO for different permanent magnetic guideways
Abdioglu, M.; Ozturk, K.; Gedikli, H.; Ekici, M.; Cansiz, A.
The development of superconductor Maglev systems depends on various disciplinary studies due to the inherent composition of available technologies. Because the fabrication cost is very effective on the Maglev, the requirement of the efficiency improvement focuses the researchers on the design considerations. In this study, the guidance force, the magnetic levitation force (MLF) and magnetic stiffness of different permanent magnetic guideway (PMG) arrangements were investigated in different cooling heights (CH) to enhance the efficiency of Maglev system. The single domain cylindrical bulk YBCO superconductors fabricated by top seeding method with the diameter of 45 mm and the height of 15 mm were used as HTS. Magnetic field distributions of the PMGs were calculated by finite element method to determine optimum HTS-PMG arrangements. We have used auxiliary onboard permanent magnets with YBCOs to improve the MLF of three pole Halbach PMG arrangements. It is seen that the efficiency of Maglev systems can be improved by using suitable HTS-PMG arrangements. In this study cost efficiency of the integrated levitation and guidance force ((Fz)max(Fx)max/(SPMG ∗ Cost)) was also determined. It is inferred from this study that the cooling height and PMG-HTS arrangement are key parameters for guidance force, levitation force, magnetic stiffness and efficiency of Maglev systems. It is believed that this study will supply useful references for practical application of HTS Maglev systems.
AtıfScopus60WoS59OpenAlex61İncele - MakaleYalnız künye2015Scopus SJRQ2GaN thin film deposition on glass and PET substrates by thermionic vacuum arc (TVA)
Pat, Suat; Korkmaz, Şadan; Özen, Soner; Şenay, Volkan
In this paper, GaN thin film production was realized by thermionic vacuum arc (TVA), a plasma deposition technique, for the first time. We present a new deposition mechanism for GaN thin films with a very short production time. Microstructure properties of samples were analyzed by X-ray diffractometry. The peak at 2θ = 72.88° corresponding to GaN (0004) was detected in XRD spectra. The surface morphology of the deposited GaN films was analyzed using field emission scanning electron microscopy and atomic force microscopy. The surface properties of the produced samples are quite different. The average roughness values were determined to be 0.48 nm for GaN/PET and 1.17 nm for GaN/glass. The optical properties (i.e., refractive index and reflection) were determined using an interferometer. Moreover, the obtained optical data were compared with bulk GaN materials. The refractive indexes were measured as 2.2, 3,0 and 2,5 for the GaN/glass, GaN/PET and bulk GaN, respectively. The transparencies of the different GaN-coated substrates are nearly the same. The obtained band gap values were measured in the energy range of 3.3-3.5 eV. TVA is a novel non-reactive plasma technique for the generation of metal organic thin films. The main advantage of this method is its fast deposition rate without any loss in the quality of the films.
AtıfScopus32WoS31OpenAlex34İncele - MakaleAçık Erişim2015Scopus SJRQ1Investigation on the morphology and surface free energy of the AlGaN thin film
Özen, Soner; Şenay, Volkan; Pat, Suat; Korkmaz, Şadan
The purpose of this paper is to analyze surface properties of AlGaN thin film produced using thermionic vacuum arc technique. Thermionic vacuum arc is an alternative deposition technique for GaN thin films that produces in a very short production time for GaN-based solid-state applications. XRD results showed that AlGaN thin film with cubic crystal structure on a amorphous glass was grown. Conductivity type of AlGaN thin film is determined as p-type by hot-probe method which is a very simple method. The surface morphology was analyzed and discussed using field emission scanning electron microscopy (FESEM) and atomic force microscopy. The contact angles in four different testing liquid and surface free energy of the AlGaN thin film were investigated by optical tensiometer.
AtıfScopus27WoS27OpenAlex28İncele - MakaleAçık Erişim2015Scopus SJRQ1Effect of onboard PM position on the magnetic force and stiffness performance of multi-seeded YBCO
Ozturk, K.; Kabaer, M.; Abdioglu, M.
Abstract In implemented studies before, although some advancements have been achieved in improving on the levitation or guidance force efficiency of YBCOs separately, both of these forces could not been enhanced simultaneously. In our study, we investigated levitation, guidance force and magnetic stiffness properties of multi-seeded YBCO bulk depending on different position of onboard PM in different CHs above a Halbach PMG to obtain larger vertical load capability, stability and relating stiffness values at the same time. The levitation, guidance force and relating stiffness measurements were carried out between multi-seeded YBCO and Halbach PMG depending on the onboard PM positions and cooling heights after the magnetic flux distributions modelling of Halbach PMG with onboard PMs. In this paper, it has clearly seen that the levitation force and the vertical magnetic stiffness values increase in optimal onboard PM position, with negligible lose in guidance force and lateral magnetic stiffness values. It is inferred from this study that reasonable position of the onboard PM according to PMG, the cooling conditions and compatibility of YBCO-PMG arrangement in point of magnetic flux distribution are key parameters for efficiency of the load, guidance force and relating magnetic stiffness of Maglev systems. The results obtained in this study have a potential on improvement of HTS Maglev system electromagnetic force capability.
AtıfScopus19WoS18OpenAlex19İncele - MakaleAçık Erişim2015Scopus SJRQ1Positive periodic solutions of nonlinear differential equations system with nonstandard growth
Ayazoglu Mashiyev, Rabil; Avci, Mustafa
In this work, we study the existence of positive periodic solutions for a p(t)-Laplacian system.
AtıfScopus2WoS2OpenAlex2İncele - MakaleYalnız künye2015Scopus SJRQ1Thermal loop test to determine structural changes and thermal stability of creamed honey: Rheological characterization
Karasu, Salih; Toker, Omer Said; Yilmaz, Mustafa Tahsin; Karaman, Safa; Dertli, Enes
This study was the first attempt to understand if thermal stability of any food product during storage could be determined. In this respect, a novel method, namely, the thermal loop test was used to determine structural changes and thermal stability of creamed honey in this study. The novelty of this method was that thermal stability of a product is tested within a number of thermal cycles over a determined range of temperature. Creamed honey was characterized in terms of physicochemical, thermomechanical and rheological properties. It showed non-Newtonian thixotropic behavior at all temperature levels (10, 25 and 40 °C). Time-dependent flow behavior was successfully defined by Weltman and second order structural models. Hysteresis loop area depended on temperature and decreased with increase in temperature. Creamed honey had liquid-like structure, showing that it had more pronounced viscous nature than elastic nature (G″ > G′). Temperature sweep tests were conducted to determine temperature dependency of η50, G′ and G″ values using Arrhenius equation. These test results confirmed the thermal stability test results, revealing that thermal loop test can be an accurate method to determine thermal stability of similar food products, as a new information. Relative structural index value (Δ) increased with number of thermal loop, suggesting that creamed honey had low thermal stability and showed a great structural change by the thermal stress applied between 5 °C and 50 °C. These results suggest that crystallized honey be abstained from large temperature fluctuations to avoid from irreversible changes in rheological characters; thus, to maintain spreadability.
AtıfScopus45WoS43OpenAlex47İncele - MakaleAçık Erişim2015Scopus SJRQ1Improvement of high strain rate and room temperature superplasticity in Zn-22Al alloy by two-step equal-channel angular pressing
Demirtas, M.; Purcek, G.; Yanar, H.; Zhang, Z.J.; Zhang, Z.F.
The Zn-22Al alloy was subjected to equal-channel angular pressing (ECAP) to improve its high strain rate (HSR) superplasticity at room temperature (RT). A well-designed two-step ECAP process formed an ultrafine-grained (UFG) microstructure with an average grain size of 200nm as the lowest one obtained so far after ECAP processing of this alloy. Also, agglomerate- and texture-free microstructure with UFG Al-rich α- and Zn-rich η-grains separated mostly by high-angle grain boundaries (HAGBs) was produced by this process. The maximum RT elongation was achieved to be 400% with a strain rate sensitivity of 0.30 at a very high strain rate of 5×10-2s-1 after the two-step ECAP process. This elongation value is the highest one obtained at RT and at all strain rates for this alloy up to now. The current results demonstrate that such an improvement in superplasticity of Zn-22Al alloy after the two-step ECAP process can enhance its applications where RT and HSR superplasticity are strongly needed.
AtıfScopus48OpenAlex48İncele - MakaleYalnız künye2015Scopus SJRQ1Effect of equal-channel angular pressing on room temperature superplasticity of quasi-single phase Zn-0.3Al alloy
Demirtas, M.; Purcek, G.; Yanar, H.; Zhang, Z.J.; Zhang, Z.F.
Quasi-single phase (dilute) Zn-0.3Al alloy was subjected to severe plastic deformation via equal-channel angular extrusion/pressing (ECAE/P), and the effects of ECAP on its room temperature (RT) and high strain rate (HSR) superplasticity and deformation mechanism were investigated. Multi-pass ECAP may refine the coarse-grained microstructure into the fine grained (FG) one. The grain size of Zn-matrix phase decreased down to 2.0m after ECAP. Many spherical Al-rich precipitates decomposed and homogeneously distributed inside the matrix phase. They are ultrafine grained (UFG) α-particles with the grain sizes ranging from 50nm to ~200nm. This special microstructure having FG and UFG micro-constituents brought about an improvement in RT superplasticity even at HSRs. While multi-pass ECAP decreased flow stress of the alloy, its elongation to failure increased substantially depending on the initial strain rates. The maximum elongation was 1000% at a low strain rate of 10-4s-1, and 350% elongation was achieved at a high strain rate of 10-2s-1. Grain boundary sliding (GBS) was found to be the main deformation mechanism in region-II as the optimum superplastic region.
AtıfScopus60WoS59OpenAlex55İncele - MakaleAçık Erişim2015Scopus SJRQ1Asymmetric Friedel-Crafts alkylation of pyrrole with nitroalkenes catalyzed by a copper complex of a bisphenol A-derived Schiff base
Özdemir, Halide Sedef; Şahin, Engin; Çakici, Murat; Kiliç, Hamdullah
The asymmetric Friedel-Crafts (FC) alkylation of pyrrole with nitroalkenes was mediated by CuBr2 and a novel bisphenol A-derived chiral catalyst at room temperature. The catalyst was found to be applicable for the asymmetric FC alkylation of pyrrole with a wide range of nitroalkenes, affording optically active alkylated pyrroles with enantioselectivities up to 94%. Furthermore, enantiomerically pure 3-nitro-2-arylpropanamides were prepared by the oxidative cleavage of the pyrrole rings in the FC products with NaIO4/RuCl3 to demonstrate the synthetic application of the products.
AtıfScopus18WoS15OpenAlex17İncele - MakaleAçık Erişim2015Scopus SJRQ1Achieving room temperature superplasticity in Zn-5Al alloy at high strain rates by equal-channel angular extrusion
Demirtas, M.; Purcek, G.; Yanar, H.; Zhang, Z.J.; Zhang, Z.F.
Multi-pass equal-channel angular extrusion/pressing (ECAE/P) was applied to the eutectic Zn-5Al alloy to achieve high strain-rate (HSR) superplasticity in that alloy at room temperature (RT) by producing ultrafine-grained (UFG) microstructure. ECAE processing transformed the coarse-grained lamellar/spherical microstructure into a unique bimodal structure having equiaxed Zn-rich η-phase with a mean grain size of 540 nm and spherical Al-rich α-phase with an average grain size of 110 nm. The α-phase particles accumulated mainly along the η-phase boundaries. This unique microstructure brought about an extraordinary improvement in HSR superplasticity of the alloy even at RT. While the strength values decreased after ECAE, the elongation to failure increased substantially. The maximum elongation was 520% at the strain rate of 10-3 s-1, still high elongation of about 400% was achieved at a high strain rate of 10-2 s-1. This extraordinary improvement in HSR superplasticity of Zn-5Al alloy was attributed to the morphologically unique bimodal microstructure in UFG regime formed after ECAE. The grain boundary sliding (GBS) was found to be the main deformation mechanism for this alloy in superplastic regime.
AtıfScopus33WoS35OpenAlex34İncele - MakaleYalnız künye2015Scopus SJRQ1A novel approach based on DEMATEL method and patent citation analysis for prioritizing a portfolio of investment projects
Altuntas, Serkan; Dereli, Türkay
The aim of this article is to propose a novel approach based on a method called Decision-Making Trial and Evaluation Laboratory (DEMATEL) and patent citation analysis for prioritizing the portfolio of investment projects. The proposed approach reflects the government's perspective and takes into account two important prioritization criteria. They are: (i) the decreasing rate of foreign trade deficits in the country and (ii) the potential to attract new investments which are not considered in the literature before. A case study from Turkey is presented to demonstrate the benefits of the proposed approach. The findings show that the proposed approach can be used easily and efficiently to prioritize investment projects among available project proposals.
AtıfScopus118WoS92İncele - MakaleAçık Erişim2014Scopus SJRQ1Steady, dynamic and creep rheological analysis as a novel approach to detect honey adulteration by fructose and saccharose syrups: Correlations with HPLC-RID results
Yilmaz, Mustafa Tahsin; Tatlisu, Nevruz Berna; Toker, Omer Said; Karaman, Safa; Dertli, Enes; Sagdic, Osman; Arici, Muhammet
In this study, natural honey was adulterated with the addition of adulterants, namely saccharose and fructose syrups at a ratio of 0%, 10%, 20%, 30%, 40% and 50% by weight. Steady, dynamic and creep tests were conducted, revealing that the changes in the flow, viscoelastic and creep behavior of natural honey were clear and remarkable. Syrup addition decreased viscosity (η), storage (G') and loss modulus (G″) values of the control honey samples. Deformation represented by the compliance (J(t)) values was more prominent in the adulterated honey samples. In addition, HPLC-RID analysis was conducted to determine major sugar composition of the adulterated samples. Pearson's correlation test indicated that there were significant (P<0.05; 0.01) correlations between sugar composition and rheology parameters, η (viscosity), K″, K* (intercepts for G″ and complex modulus (G*), respectively) and η0 (viscosity of Maxwell dashpot), suggesting that K', K″, K* and η0 could be prominent indicators for presence of saccharose or fructose syrups added in natural honey within the studied concentration levels. These results suggested that use of steady, dynamic and creep analysis would be a novel and potential approach to detect honey adulteration by fructose and saccharose syrups.
AtıfScopus81WoS72OpenAlex80
İncele - MakaleAçık Erişim2014Scopus SJRQ1Nonlinear dynamic analysis of base isolated cable-stayed bridge under earthquake excitations
Atmaca, Barbaros; Yurdakul, Muhammet; Ateş, Şevket
In this paper, it is aimed to determine the earthquake effects on cable-stayed bridge isolated by single concave friction pendulum bearings (SCFP). In this context, Manavgat cable-stayed bridge is selected as a numerical application. The selected bridge has 202. m composite deck and 42. m steel tower. 3D finite element models (FEM) of the base isolated and non-isolated bridge are modeled by using SAP2000. Three different earthquakes which are 11 December 1999 Düzce, 23 November 2011 Van and 13 March 1992 Erzincan earthquakes are subjected to the 3D FEM models in order to determine the seismic behavior of the bridges. BOL-090 and BOL-000; ERCIS-EW and ERCIS-NS; ERZ-NS and ERZ-EW components of ground motions obtained from PEER and AFAD are applied to the bridges at the longitudinal and transverse directions, respectively. Nonlinear time history analysis is executed to determine the dynamic responses of the bridge. Comparison of dynamic behavior of isolated and non-isolated bridge with and without the SCFP bearings under three different earthquake motions has been conducted. The results obtained from analyses of 3D FEM of the bridge are presented by graphics and tables in detail. It is seen that using of isolation system reduces the destructive effects of earthquakes on the bridge.
AtıfScopus36WoS28OpenAlex36İncele - Derleme MakaleYalnız künye2013Scopus SJRQ1Toward a sustainable energy future in Turkey: An environmental perspective
Serencam, Huseyin; Serencam, Ugur
As long as the energy future of Turkey is concerned there is a consensus among all parties involved in the subject that a strong sustainability based on diverse range of renewable and variety of sources with efficient and fair use of energy is a must. The main criterion in this approach is to use energy with the least possible greenhouse gases and other harmful emissions. A shift in focus to meeting the needs of energy service sector will be immediately felt in the sustainable energy future in Turkey. Another important aspect of the sustainable energy future of Turkey is that all energy users, as more knowledgeable and active participants will be more involved in various stages of the process. However, Turkey has a long way to reach this vision, because of growing greenhouse emissions related to energy production and utilization of alternative energy is slow. Besides, the intensity of energy of the Turkish economy is decreasing slower than many other OECD countries. In addition, energy consumption per person in Turkey is far above the service needs, even for modern lifestyles. There are substantial obstacles on the way to a sustainable energy future of Turkey, such as various aspects of economic structure, a misdirected energy market process, and a lack of vision among the decision makers.
AtıfScopus12WoS10OpenAlex12İncele - MakaleYalnız künye2013Scopus SJRQ1An experimental exergetic comparison of four different heat pump systems working at same conditions: As air to air, air to water, water to water and water to air
Çakir, Uǧur; Çomakli, Kemal; Çomakli, Ömer; Karsli, Süleyman
In this study, we designed a multifunctional heat pump system using just one scroll compressor and which can be run in four different modes, namely air to air, air to water, water to water and water to air, in order to make an experimental energetic and exergetic performance comparison. Experimental system consists of two condensers and two evaporators and uses R22 as working fluid. One of the evaporators and condensers uses water and the others use air as heat source/sink. Heating capacities of four heat pump types are equal to each other. It is realized by adjusting the mass flow rate and temperature level of external fluid of condenser. Results show that the heat pump unit which has the maximum COP (coefficient of performance) value is water to air type with 3.94 and followed by water to water type with 3.73, air to air type with 3.54 and air to water type with 3.40. Ranking of four heat pump types with respect to their mean exergy efficiency is as follows; water to air type with 30.23%, air to air type with 30.22%, air to water type with 24.77% and water to water type with 24.01%. Exergy destruction rates of the systems were investigated in this study and the results revealed that the heat pump type which has the maximum exergy destruction is air to air type with 2.93kW. The second highest one is air to water type with 2.84kW. The third highest one is water to air type with 2.64kW and last one is water to water type with 2.55kW. It is understood that the temperature of the evaporator external fluid affects the exergetic efficiency of the system more than the mass flow rate. In contrast to the previous, the dominant parameter which has more important effect on the exergy destruction of the heat pump unit is the mass flow rate of evaporator external fluid.
AtıfScopus55WoS46İncele - BildiriAçık Erişim2011The investigating pre-service teachers' learning styles with respect to the gender and grade level variables
Metin, Mustafa; Yilmaz, Gül Kaleli; Birişçi, Salih; Coşkun, Kerem; Akcamete, G; Uzunboylu, H; Oulmu, S; Karahoca, A; Babadoan, C; Ozdamli, F
The aim of this study is to investigate pre-service teachers' learning styles in terms of gender and grade level variables. The study was carried out at spring semester of 2010. The sample of the study consisted of 347 pre-service teachers at the Department of Primary and Science Teacher Education in Faculty of Education at Artvin Çoruh University. "Kolb Learning Style Inventory" was used as a data collection tool. The data were analyzed by using frequency, percentage, means, standard deviation, independent samples t-test and one-way ANOVA. The results show that the dominant learning style among the students is accommodator and it is followed by convergent, divergent and assimilator learning style. There was not significantly difference between students' learning style and gender and between students' learning style and grade level.
AtıfScopus7WoS7OpenAlex16İncele - MakaleAçık Erişim2010Scopus SJRQ2Complexation of metal ions with the novel azathia crown ethers carrying anthracene pendant in acetonitrile-dichloromethane
Ocak, Ümmühan; Ocak, Miraç; Başoǧlu, Aysel; Parlayan, Semanur; Başaran, Dilek; Alp, Hakan; Kantekin, Halit
A series of crown ethers carrying an anthracene group with nitrogen-sulfur donor atom, which differ in having three, four and five sulfur atoms in the macrocycle was designed and synthesized by the reaction of the corresponding macrocyclic compound and 9-chloromethyl-anthracene. The influence of metal cations such as Al3+, Zn2+, Fe2+, Fe3+, Co2+, Ni2+, Mn2+, Cu2+, Cd2+, Hg2+ and Pb2+ on the spectroscopic properties of the ligands was investigated in acetonitrile-dichloromethane (1:1) by means of absorption and emission spectrometry. Absorption spectra show isosbestic points in the spectrophotometric titration of Al3+, Zn2+, Fe2+, Fe3+, Cu2+, Hg2+ and Pb2+ the results of which disclosed the complexation compositions and complex stability constants of the novel ligands with these cations. The monoazapentathia crown ether showed sensitivity for Al3+ with linear range and detection limit of 2.6 × 10-6 M-2.6 × 10-5 M and 8.1 × 10-7 M, respectively.
AtıfScopus10WoS9OpenAlex10İncele - DergiBiocatalysis and Agricultural Biotechnology
- DergiEngineering Applications of Artificial Intelligence