Elektronik ve Haberleşme Mühendisliği Bölümü Yayın Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/260
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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 Diffraction Theory of Waves by Resistive Surfaces(2010) Umul, Yusuf Ziya; Yalçın, UğurDiffraction of scalar plane waves by resistive surfaces are investigated by defining a new boundary condition in terms of the Dirichlet and Neumann conditions. The scattering problems of waves by a resistive half-plane and the interface between resistive and perfectly magnetic conducting half-planes are examined with the developed method. The resulting fields are plotted numerically. The numerical results show that the evaluated field expressions are in harmony with the theory.Article Citation - Scopus: 18Diffraction Theory of Waves by Resistive Surfaces(Electromagnetics Academy, 2010) Yalçin, U.; Umul, Y.Z.Diffraction of scalar plane waves by resistive surfaces are investigated by defining a new boundary condition in terms of the Dirichlet and Neumann conditions. The scattering problems of waves by a resistive half-plane and the interface between resistive and perfectly magnetic conducting half-planes are examined with the developed method. The resulting fields are plotted numerically. The numerical results show that the evaluated field expressions are in harmony with the theory.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 - Scopus: 11Rigorous Expressions for the Equivalent Edge Currents(Electromagnetics Academy, 2009) Umul, Y.Z.An exact form for the equivalent edge current is derived by using the axioms of the modified theory of physical optics and the canonical problem of half-plane. The edge current is expressed in terms of the parameters of incident and scattered rays. The analogy of the method with the boundary diffraction wave theory is put forward. The edge and corner diffracted waves are derived for the problem of a black half-strip.Conference Object Hydrogen Hosting on Aluminum-Doped Boron Clusters: Density Functional Theory(Institute of Physics Publishing, 2009) Böyükata, M.; Güvenç, Z.B.The geometries, stabilities, and energetics of aluminum doped boron clusters, up to 13-atom, and their various hydrogenated complexes have been investigated via the density functional theory (DFT). The geometry optimizations have been carried out by using B3LYP functional and 6-311++G11 basis set. Up to 5-atom clusters arrangements of the atoms, in the most stable structures, have two-dimensional forms. From 6- to 13-atom clusters three-dimensional forms are favored by the lowest energy structures. Hydrogen hosting effects the structures of AlBn clusters. Adding an Al atom to the cage B12 leads structural changes but hydrogenated boron, B12H12 can resist to Al effect. © 2009 IOP Publishing Ltd.Conference Object Citation - Scopus: 31A New Design of Dual Band Microstrip Bandpass Filter Based on Peano Fractal Geometry: Design and Simulation Results(2013) Mezaal, Y.S.; Eyyuboglu, H.T.; Ali, J.K.The proposed filter design topology is based on dual coupled resonators constructed in the form of Peano fractal geometry. A dual-band microstrip bandpass filter with a quasi-elliptic response has been designed for first time based on 1st iteration Peano fractal geometry at resonant frequencies of 2.25 GHz and 4.825 GHz using a substrate of a relative dielectric constant of 10.8 and thickness of 1.27 mm. The performance of the bandpass filter structure has been analyzed using a method of moments (MoM) based software package, Microwave Office 2009, from Advanced Wave Research Inc. Results show that this filter possesses good frequency response characteristics in addition to dual bands gained which can be used for modern communication applications. © 2013 IEEE.Article Citation - WoS: 24Citation - Scopus: 24Molecular Dynamics Simulation of the Melting Behaviour of 12-, 13-, 14-Atom Icosahedral Platinum Clusters(Iop Publishing Ltd, 2004) Sebetci, A; Guvenc, ZBUsing the molecular dynamics simulation technique, we have studied the melting behaviour of free, icosahedral Pt-N clusters in the size range of N = 12-14. The Voter and Chen version of an embedded-atom model, derived by fitting to experimental data of both the diatomic molecule and bulk platinum simultaneously, has been employed in this study. We present an atom-resolved analysis method that includes physical quantities such as the root mean square bond-length fluctuation and coordination number for individual atoms as functions of temperature. The results show that while the 13-atom icosahedron and the 12-atom cluster with a vacancy on the icosahedral surface exhibit one-stage melting, the 14-atom cluster with an adatom on the icosahedral surface undergoes two-stage melting, as the temperature increases.Article Citation - WoS: 1Citation - Scopus: 1Symmetric Space Σ-Model Dynamics: Current Formalism(World Scientific Publ Co Pte Ltd, 2007) Yilmaz, Nejat T.After explicity constructing the symmetric space sigma model Lagrangian in terms of the coset scalars of the solvable Lie algebra gauge in the current formalism, we derive the field equations of the theory.Article Citation - WoS: 6Citation - Scopus: 6Field Correlations for Off-Axis Gaussian Laser Beams in Atmospheric Turbulence(Amer Geophysical Union, 2014) Baykal, YahyaThe absolute field correlations in atmospheric turbulence are evaluated for the off-axis optical Gaussian beam incidence. Evaluations in the practical range of the source and the turbulent medium parameters show that an increase in the diagonal length at the receiver plane causes the absolute field correlations of the off-axis Gaussian beam to decrease. At a fixed receiver diagonal length, the off-axis Gaussian beams having smaller displacement parameters and larger source sizes exhibit larger absolute field correlations. Comparing the absolute field correlations of the off-axis Gaussian beams in atmospheric turbulence with their no turbulence counterparts, it is observed that the behavior of the absolute field correlation variations remains the same; however, the diminishing of the absolute field correlations in turbulence occurs at smaller diagonal lengths.