Sürdürülebilir Kalkınma Amaçları

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• MakaleAçık Erişim2024Scopus SJRQ2/r/bayburt/10972
  Reflective Polarization Conversion with Multi-Functional, Ultrathin Metasurface for Ku-and K-Band Applications

  Teber, Ahmet

  Reflective polarization conversions with a simplistic design of an ultrathin, single-layered, and multi-functional anisotropic metasurface as a polarization converter is utilized for Ku-and K-band applications. The designs with two substrate thicknesses (0.095λ0 and 0.069λ0, respectively) are capable of a cross-polarization converter (CPC) and a linear-to-circular (LTC) polarization conversion. The design with 0.095λ0 thickness achieves a CPC between 17.96 and 26.90GHz with the efficiency of more than 90% and a relative bandwidth of 40% under normal incidence. It maintains angular stability by altering the oblique incidence angles up to 300 with greater than 80% of the PCR in the K-band. Meanwhile, an LTC in two frequency bands, 10.30-10.53GHz and 28.65-29.70GHz, is also numerically demonstrated. The second design with 0.069 λ0 thickness provides a CPC above the PCR value of 87% in the frequency range from 10.46-23.05GHz (covering the entire Ku-and part of the K-band) with angular stability of 40 above the PCR value of 80%. In the meantime, an LTC with relative bandwidth of 75% in the frequency range from 9.53-9.79&24.74-25.27GHz is numerically revealed. These polarization converters exhibit relatively good performances of facile structure and multi-functional properties, which can be useful in Ku-and K-band applications.

  AtıfScopus5·WoS3·OpenAlex5·TR Dizin1

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• MakaleAçık Erişim2021Scopus SJRQ3/r/bayburt/13248
  Aggressive environment performance of low energy cements containing fly ash

  Gokce, H. Suleyman; Simsek, Osman

  In this study, compressive strength performance of boron active belite cement containing fly ash at the ratios of 0, 10, 20, and 30% (by weight of cement) is researched against aggressive environments; sea water, 5% sodium sulphate solution, and 5% ammonium nitrate solution in addition to tapping water. Alternative low energy cement i.e., Portland-composite cement was used and its results were compared with those of boron active belite cement. Early strength losses (reaching up to 40%) of the boron active belite cement with incorporation of fly ash up to 30% were found to be less pronounced than those (reaching up to 51%) of Portland-composite cement in tapping water. Although, the losses were highly compensated with the prolonged curing period (90 days), boron active belite cement and Portland-composite cement kept their losses up to 14% and 36%, respectively. Residual mechanical properties (reaching up to 67%) of boron active belite cement against aggressive environments were found almost similar to those of Portland-composite cement in presence of 30% fly ash. In conclusion, the study shows that belite cements with low fly ash contents can be a reasonable alternative for specific applications such as mass concrete, hot weather concreting especially in aggressive environments.

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  AtıfScopus3·WoS1·OpenAlex5·TR Dizin1

  İncele
• MakaleAçık Erişim2020Scopus SJRQ3/r/bayburt/13468
  Beamforming radiation properties of absorbing/transparent zones-added horn antenna

  Teber, Ahmet

  In this study, we present beamforming of radiation patterns on a transmitter horn antenna by mounting an electromagnetic wave absorber, in which electromagnetic wave absorber is fabricated as concentric zones. The concentric zones consist of an absorbing material of manganese soft spinel ferrite blended with multi-walled carbon nanotubes with the thickness of 1 mm installed on the aperture of the antenna working in Ku-band. We have experimentally measured scattering parameter of transmission, S21, using a vector network analyser to perform radiation patterns in polar coordinates. As compared to the radiation properties of air horn antenna and absorbing/transparent zone-added horn antenna produces an appreciable effect to concentrate radiation beam in the main, side and back lobes with reducing side and back lobe levels for each frequency in H-plane. For the radiation pattern in E-plane, we have observed the suppressed side lobes at three frequencies of 15 GHz, 17 GHz and 18 GHz. The results indicate that the absorbing/transparent zone keeps an important role for further development of the applications of directional antennas so that the effective radiation is to be significantly concentrated.

  AtıfScopus1·OpenAlex2

  İncele
• MakaleYalnız künye2019Scopus SJRQ3/r/bayburt/12410
  Physicochemical and palynological characterization of the onobrychis miller (fabaceae) honey

  Ozenirler, Cigdem; Gencay Celemli, Omur; Ecem Bayram, Nesrin; Dikmen, Fatih; Zare, Golshan; Celikbicak, Omur; Sorkun, Kadriye

  The purpose of this study was to contribute toward characterizing the general properties of the Onobrychis Miller (sainfoin) honey.We analyzed 21 samples of Onobrychis honeys, which were collected in 2013, from Northeast Anatolia according to their microscopic and physicochemical features (fructose/glucose (F/G) ratio, 5-(hydroxymethyl) furan-2-carbaldehyde (HMF) value, and volatile compounds). The relationships were examined between these variables with statistical methods such as principal component, regression, and correlation analyses. Statistical analyses revealed certain correlation patterns between several parameters. Onobrychis radiata (Desf.) M. Bieb., O. tournefortii (Willd.) Desv., O. oxyodonta Boiss. and Onobrychis spp. pollens were identified.TPN-10 ranged from 6532 to 481157 while the HMF values were between 0.1-7.5 mg/kg and F/G ratios were between 0.8-1.3. Alcohols, aldehydes, aliphatic acids and their esters, carboxylic acids and their esters, hydrocarbons, flavonoids, ketones, sugars and vitamins were identified in the honey samples within ranges of 0-11.95%, 0-16.76%, 0-24.72%, 0-1.86%, 0-14.71%, 2.74-7.09%, 0-27.02%, 5.12-51.39%, and 0-21.36%, respectively.Although it was not significant, a positive correlation between flavonoids and Onobrychis pollen number was calculated via correlation analysis. There was no meaningful correlation between Onobrychis pollen number and other parameters. Although a negative trend between flavonoids and sugars was observed, it was not significant. F/G ratio was found to be positively correlated with sugars, HMF, and TPN-10 of which the latter two parameters had significant values. Furthermore, a significant positive correlation between TPN-10 and HMF was also detected.

  AtıfScopus3

  İncele
• MakaleYalnız künye2018Scopus SJRQ2/r/bayburt/14131
  Plant Origins of Propolis from Hakkari, Turkey

  Ecem Bayram, Nesrin; Sorkun, Kadriye; Cevahir Oz, Gul

  In this study, palynological analysis of 64 propolis samples from Hakkari province in Eastern Anatolia Region of Turkey was carried out. By microscopic analysis method, pollen diagnosis was made in propolis samples, and plants which may be propolis sources, were estimated. As a result, 71 plant taxa belonging to 34 families were identified at different rates in propolis samples. The pollens of the plants belonging to the family Apiaceae (2.7%-35%), Asteraceae (3.4%-35.4%) and, Fabaceae (12%-66%) were considerably found in the propolis of the Hakkari province. This study is the first report introducing the plant profile of Hakkari propolis in detail.

  AtıfWoS1

  İncele
• MakaleYalnız künye2018Scopus SJRQ2/r/bayburt/14062
  Anti-genotoxic Effects of Schiff bases and their Mn(III) Complexes Containing L-Aspartic acid and L-Phenylalanine

  Hasanoglu Özkan, Elvan; Kizil, Hamit Emre; Sakiyan, Iffet; Nartop, Dilek; Sari, Nursen; Agar, Guleray

  The purpose of the research was to evaluate the genotoxic and anti-genotoxic properties of Schiff bases and their Mn (III) complexes containing L-aspartic acid, and L-phenylalanine. The anti-genotoxic properties of four compounds in human lymphocytes cells were investigated by sister chromatid exchanges (SCEs) test system against aflatoxin Bi (AFBi). The results showed that compounds have strong anti-genotoxic properties.

  AtıfWoS3

  İncele
• MakaleYalnız künye2012Scopus SJRQ3/r/bayburt/14026
  The prediction of heat transfer and fluid characteristics for equilateral triangular bodies in tandem arrangement by artificial neural networks

  Manay, Eyüphan; Güneş, Sibel; Akçadirci, Esra; Özceyhan, Veysel; Çakir, Ǔur; Çomakli, Ömer

  The objective of this study is to investigate the effect of the spacing between equilateral dual triangular bodies symmetrically placed into the channel axis under steady state conditions on heat transfer and fluid characteristics by using artificial neural networks (ANN). The Back Propagation (BP) training algorithm was applied to train the model. The successful application proved that ANN model can be used for predicting the Nusselt number and skin friction coefficient as a convenient and effective method. The distribution of local Nusselt number, skin friction coefficient along the channel wall and overall enhancement ratio of all investigated cases are presented.

  AtıfScopus5

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