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: 2Citation - Scopus: 2Ber Anaylsis for Super Lorentz-Gaussian Laser Beams Propagating in Turbulent Media(Gazi Univ, Fac Engineering Architecture, 2013) Gokce, Muhsin C.; Gökçe, Muhsin Caner; Sari, Filiz; Ozek, Faruk; Elektronik ve Haberleşme MühendisliğiIn this work, BER-SNR variation of super Lorentz-Gaussian laser beam that propagating horizontally path in turbulent media is analyzed. Using scintillation index which is obtained by extented Huygens-Fresnel principle, BER - SNR value is calculated. Matlab program is used to show BER - SNR variation depending on link distance and beamwidth. To conclude, in short link range, super Lorentz-Gaussian beam is proven to be better link performance superior to commercially available Gaussian beam.Article Citation - WoS: 1Citation - Scopus: 1Structures and Energetics of Cu21-Cu71 Clusters: a Molecular Dynamics Study(Gazi Univ, 2009) Güvenç, Ziya Burhanettin; Cetin, Saime Sebnem; Ozcelik, Suleyman; Guvenc, Ziya B.; Bilgisayar MühendisliğiUsing Molecular Dynamics and thermal quenching simulations the stable geometrical structures and energies of Cun (n=21-71) clusters are identified. The interaction between the cluster atoms is modeled by an EmbeddedAtom Potential Surface, Voter and Chen's version. The stable geometrical structures and energies are obtained from 500 phase space coordinates generated along high-energy trajectories. The internal energy (about T=2500 K) is above the melting temperature of the Cun clusters. The thermal quenching technique is employed to remove slowly the internal kinetic energy of the clusters. Because of this slow minimization process the locally stable isomers are separated from those meta-stable ones.Correction Uniform Theory for the Diffraction of Evanescent Plane Waves: Publisher's Note (Vol 24, Pg 2426, 2007)(Optical Soc Amer, 2007) Umul, Yusuf Z.Article Investigation of Factors Affecting Noise Robustness in Voice Activity Detectors(Gazi Univ, Fac Engineering Architecture, 2023) Ozaydin, SelmaIn this manuscript, some voice activity detectors (VADs) in the literature were examined in terms of factors affecting their robustness under different acoustic noise conditions and in this context, the changes in detection accuracy rates according to changing noise conditions were tested. In this scope, the effect of situations such as whether the threshold value used in the decision phase in VAD methods is fixed or adaptive, the analysis window is short or long, the use of more than one feature vector together has been evaluated and analyzed comparatively. While three of the four different VAD detectors examined in this manuscript use feature vectors within the short-term analysis window while generating the decision result, one decides according to the measurement result of long-term spectral vectors. The VAD detectors in the article have been tested using the NOIZEUS noisy speech database. Thus, the performance of the analyzed VADs has been evaluated under different acoustic conditions using an extensive database that has already taken place in the literature. During the testing of the analyzed VADs, different input noise speech signals with environmental background noises between [15-0dB] such as restaurant, car, street, or station were tested. Tests were carried out using objective test measurement methods and the detection accuracy rate of each VAD method was measured. The results showed that each method gave different endurance performance in adverse environmental conditions.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.Article Citation - WoS: 2Citation - Scopus: 3Diffraction in Time of an Entangled Non-Relativistic Quantum Particle(Iop Publishing Ltd, 2021) Umul, Yusuf ZiyaThe diffraction process of an entangled non-relativistic quantum particle in time domain is investigated. The scenario consists of two entangled spin-0 particles and a quantum shutter, which is opened at an initial time. The particles are traveling in two opposite sides and expressed with a single wave function. The integral solution of the Schrodinger equation is considered for two particles case. The initial condition is expressed in terms of an entangled wave function. The time-diffracted matter wave is obtained in terms of the Fresnel integral. The effect of the phenomenon of diffraction in time is examined numerically for the entangled system of two particles.Article Citation - WoS: 2Citation - Scopus: 2Diffraction of Electromagnetic Waves by a Resistive Half-Plane in Magneto-Ionic Plasma(Wiley-v C H verlag Gmbh, 2020) Umul, Yusuf ZiyaThe interaction of magnetic polarized electromagnetic wave with a resistive half-plane in magneto-ionic plasma is investigated. The method of transition boundary is used for the evaluation of the diffracted wave. The excitation of surface waves is examined in the medium and their diffracted fields are derived by using the diffraction theory for grazing incidence. The uniform field expressions are obtained with the aid of the uniform theory for evanescent waves. The behaviours of the derived scattered waves are studied numerically.Article Citation - WoS: 5Citation - Scopus: 4Interaction of Electromagnetic Plane Waves With an Impedance Half-Plane in an Anisotropic Medium(Optical Soc Amer, 2020) Umul, Yusuf ZiyaThe diffraction process of electromagnetic plane waves by an impedance half-plane in anisotropic medium is investigated. In this case, the permittivity of the space is expressed in terms of a tensor. The incident wave is considered for magnetic polarization. The diffracted fields are obtained with the aid of the method of transition boundary. It is shown that the diffraction wave reduces to the correct field expressions for the limiting cases. The total field and its components are compared with the literature numerically. (C) 2020 Optical Society of America