Yazar "Tezekici, Bekir S." seçeneğine göre listele

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    Experimental study for predicting the specific heat of water based Cu-Al2O3 hybrid nanofluid using artificial neural network and proposing new correlation
    (Wiley-Hindawi, 2020) Colak, A. Batur; Yildiz, Oguzhan; Bayrak, Mustafa; Tezekici, Bekir S.
    In this study, an artificial neural network model has been created in order to estimate the specific heat of Cu-Al2O3/water hybrid nanofluid based on temperature (T) and volume concentration (phi). Specific heat values of the Cu-Al2O3/water hybrid nanofluid prepared in five-volume concentration were measured experimentally in the 20 degrees C to 65 degrees C temperature range. The dataset was reserved into three primary parts, with the inclusion of 901 (70%) for the training, 257 (20%) for the test and 129 (10%) for the validation. As a result of comparison with experimental values, it is concluded that this model predicts specific heat with R-value of 0.99994 and an average relative error of approximately 5.84e-9. In addition, a mathematical correlation has been developed to estimate the specific heat of the Cu-Al2O3/water hybrid nanofluid. The data acquired from the mathematical correlation, developed, were in great correlation with all the experimental values with an average deviation of -0.005%. This result has revealed that the developed mathematical correlation is an ideal design for estimating the specific heat of the Cu-Al2O3/water hybrid nanofluid.
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    Performance of Joint Relay and Antenna Selection in the Full-Duplex Amplify-and-Forward Relay Networks
    (Springer, 2017) Toka, Mesut; Kucur, Oguz; Tezekici, Bekir S.
    This paper focuses on the joint relay and antenna selection problem in dual hop full-duplex (FD) relay network with one source, one destination and N FD amplify-and-forward relays in flat Rayleigh fading channels. In the network, the source and destination are both equipped with single antenna, and all of the relays are equipped with antennas for reception and antennas for transmission. For this FD relay system, we investigate different relay selection schemes such as best relay selection, partial relay selection and reactive relay selection together with the best single receive/transmit antenna of the selected relay for the source-to-relay/relay-to-destination links based on the instantaneous channel conditions. To facilitate comparisons between the relay selection schemes, we derive closed-form outage probability (OP), and calculate bit error rate numerically. Moreover, asymptotic approximations of the OP are also derived. Analytical results are validated by the Monte Carlo simulations.