Elektronik ve Haberleşme Mühendisliği Bölümü Yayın Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/260
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Article Citation - WoS: 1Citation - Scopus: 1Determination of Chemisorption Probabilities of Hydrogen Molecules on a Nickel Surface by Artificial Neural Network(Croatian Chemical Soc, 2008) Güvenç, Ziya Burhanettin; Boeyuekata, Mustafa; Kocyigit, Yuecel; Guevenc, Ziya B.; Böyükata, Mustafa; Bilgisayar MühendisliğiDissociative chemisorption probabilities for H-2(v, j) + Ni(100) collision systems have been estimated by using Artificial Neural Network (ANN). For training, previously determined probability values via molecular dynamics simulations have been used. Performance of the ANN, for predicting any quantities in the molecule-surface interaction, has been investigated. Effects of the surface sites and the rovibrational states of the molecule on the process are analyzed. The results are in good agreement with the related previous studies.Article Citation - Scopus: 2A Compact Size Multiband Printed Monopole Antenna With Triple Sense Circular Polarization for Wireless Applications(Natl inst Optoelectronics, 2020) Al-Mihrab, M.; Salim, A.; Al-Saedi, H.; Ali, J.A penta-band printed monopole antenna based on a hexagonal open loop shape is presented in this paper. The proposed antenna demonstrated a variety in the polarization. Antenna is loaded with some parts and two stair-shaped slits is created in the partial ground plane for enhancing the multiband behavior. A circularly polarized (CP) waves are generated at a three bands with impedance bandwidths (IBWs) of 10.62%, 33.65% and 8.61% centered at 1.60, 5.20 and 6.50 GHz and 3-dB axial ratio bandwidths (ARBWs) of 9.10%, 7.58%, and 4.41% respectively. While a linearly polarized (LP) waves at the other two bands over ranges (2.51-2.64 GHz) and (3.10-3.31 GHz). Besides, the proposed antenna showed a different sense of circular polarization; right hand, left hand, and right hand. The antenna is simulated and fabricated on an FR-4 (glass epoxy) substrate with relative permittivity of 4.6, thickness of 1.6 mm and a loss tangent of 0.02. The properties of multiband and circular polarization, makes the proposed antenna candidates for many modern wireless applications.Article Citation - WoS: 18Citation - Scopus: 19Scattering by an Impedance Half-Plane: Comparison of the Solutions of Raman/Krishnan and Maliuzhinets/Senior(Electromagnetics Acad, 2009) Umul, Y. Z.There are three approaches for the solution of the diffraction problem of plane waves by an impedance half-plane in the literature. The diffracted field expressions, obtained by the related methods, are compared numerically. The examination of the scattered field shows that the most reliable solution is the field representation of Raman and Krishnan. Since the diffracted fields of Senior and Maliuzhinets do not compensate the discontinuities of the geometrical optics waves at the transition regions.Article Citation - WoS: 3Citation - Scopus: 4Po and Ptd Approach To the Diffraction Problem by a Resistive Half-Plane(Taylor & Francis Ltd, 2014) Basdemir, Husnu DenizDiffracted fields from a resistive half-plane were investigated by the method of physical optics (PO) and the physical theory of diffraction. The coefficient of the PO scattering integral was derived for the first time for the resistive half-plane. Uniform fringe field expressions were obtained in terms of the Fresnel functions. The resultant expressions of the fringe fields were plotted and analyzed numerically.Article Citation - WoS: 4Citation - Scopus: 4Electric Charges That Behave as Magnetic Monopoles(E M W Publishing, 2010) Umul, Y. Z.The memristor theory of Chua [1] provides a connection with the charge and magnetic flux in an electric circuit. We define a similar relation for the electric and magnetic flux densities in electromagnetism. Such an attempt puts forward interesting results. For example, the magnetic charges do not exist in nature however the electric charges behave as the magnetic monopoles in special media. We support our theory with the results of the recent experiments on materials named as spin ice.Editorial Citation - WoS: 3Citation - Scopus: 2Reply To the "comments on 'fringe Waves in an Impedance Half-Plane(E M W Publishing, 2014) Basdemir, Husnu DenizArticle Citation - WoS: 8Citation - Scopus: 7Bit Error Rate of a Gaussian Beam Propagating Through Biological Tissue(Taylor & Francis Ltd, 2020) Arpali, Serap Altay; Arpali, Caglar; Baykal, YahyaThe scintillation index and bit error rate (BER) of a Gaussian beam propagating in a weakly turbulent soft tissue are formulated and analysed numerically. The scintillation indices are plotted against half of the measured slope in the range of power-law scaling at different tissue parameters, such as the random variations in the refractive index of the tissue, outer scale of the tissue turbulence and the tissue length between the optical source and the detector. Moreover, BERs of Gaussian beams against the signal to noise ratio (SNR) are examined for different tissue parameters. Our graphical results show that the scintillation index and BER increase with larger outer scales, longer tissue lengths and larger random variations in the refractive index of the tissue. In comparison with the spherical wave propagation, it was found that Gaussian beam yields larger scintillation index and BER values.Article Citation - WoS: 16Citation - Scopus: 18Adaptive Optics Correction of Scintillation in Underwater Medium(Taylor & Francis Ltd, 2020) Baykal, YahyaAdaptive optics correction of the scintillation index of a Gaussian laser beam in underwater turbulence is studied. To introduce the adaptive optics correction, filter functions providing the piston, tilt and astigmatism effects are adapted to promote the spectrum of underwater turbulence. The reduction of the scintillation index due to the individual piston, tilt, astigmatism effects and their sum is examined versus the ratio of temperature to salinity contributions to the refractive index spectrum, the rate of dissipation of mean squared temperature, the rate of dissipation of kinetic energy per unit mass of fluid, receiving aperture diameter, source size, link length and the wavelength. For any value of underwater turbulence parameter, the most effective adaptive optics corrections are found to be the piston, tilt and astigmatism, respectively.Article Citation - WoS: 15Citation - Scopus: 16Scintillation Behaviour of Vortex Beams in Strong Turbulence Region(Taylor & Francis Ltd, 2016) Eyyuboglu, H. T.We study the scintillation behaviour of vectorial vortex beams in strong turbulence region. For this purpose, a list of vortex source beams is prepared. Then their scintillation performances are analysed one by one using the random phase screen approach. The results indicate that there will always be scintillation reductions with increasing values of topological charge, although its effect will diminish as we go towards higher values of the topological charge. The increases in the other specific beam parameters seem to have opposite effect. For the vectorial Hermite Gaussian beam, the use of higher orders will also aid scintillation reductions. It is foreseen that the outcome of this study will be useful for long haul optical communication links.Correction Citation - WoS: 15Citation - Scopus: 21Higher Order Annular Gaussian Laser Beam Propagation in Free Space (Vol 45, Art No 038002, 2006)(Spie-int Society Optical Engineering, 2006) Eyyuboglu, HT; Yenice, YE; Baykal, YPropagation of higher order annular Gaussian (HOAG) laser beams in free space is examined. HOAG beams are defined as the difference of two Hermite-Gaussian (HG) beams; thus, they can be produced by subtracting a smaller beam from a larger beam, that are co-centered and both possess HG mode field distributions. Such beams can be considered as a generalization of the well-known annular Gaussian beams. We formulate the source and receiver plane characteristics and kurtosis parameter of HOAG beams propagating in free space and evaluate them numerically. In comparison to HG beams, HOAG beams have a broader beam size with outer lobes of kidney shape. The amount of received power within the same receiver aperture size, that is, power in bucket, is generally lower for higher order beams. The convergence of the kurtosis parameter to an asymptotic value for higher order beams takes much longer propagation distances compared to zero-order beams. (c) 2006 Society of Photo-Optical Instrumentation Engineers.