Elektronik ve Haberleşme Mühendisliği Bölümü

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Citation - Scopus: 30
A 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.; 7688
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.
Citation - WoS: 37
Citation - Scopus: 42
A reliable and competitive mathematical analysis of Ebola epidemic model
(Springer, 2020) Rafiq, Muhammad; Baleanu, Dumitru; Ahmad, Waheed; Abbas, Mujahid; Baleanu, Dumitru; 56389; Matematik
The purpose of this article is to discuss the dynamics of the spread of Ebola virus disease (EVD), a kind of fever commonly known as Ebola hemorrhagic fever. It is rare but severe and is considered to be extremely dangerous. Ebola virus transmits to people through domestic and wild animals, called transmitting agents, and then spreads into the human population through close and direct contact among individuals. To study the dynamics and to illustrate the stability pattern of Ebola virus in human population, we have developed an SEIR type model consisting of coupled nonlinear differential equations. These equations provide a good tool to discuss the mode of impact of Ebola virus on the human population through domestic and wild animals. We first formulate the proposed model and obtain the value of threshold parameter R0 for the model. We then determine both the disease-free equilibrium (DFE) and endemic equilibrium (EE) and discuss the stability of the model. We show that both the equilibrium states are locally asymptotically stable. Employing Lyapunov functions theory, global stabilities at both the levels are carried out. We use the Runge-Kutta method of order 4 (RK4) and a non-standard finite difference (NSFD) scheme for the susceptible-exposed-infected-recovered (SEIR) model. In contrast to RK4, which fails for large time step size, it is found that the NSFD scheme preserves the dynamics of the proposed model for any step size used. Numerical results along with the comparison, using different values of step size h, are provided.
A Sequential Coding Approach for Short Length LT Codes over A WGN Channel
(2017) Gazi, Orhan; Gazi, Orhan; Elektronik ve Haberleşme Mühendisliği
Luby Transform (LT) codes which can be considered as one of the first type of rate less codes are introduced to be an efficient erasure code. In such codes a fountain of encoded symbols is continuously transmitted until the successfully delivery of all the data packets. Whenever the receiver collects N noisy encoded symbols the decoding operation starts. Usually belief propagation (BP) algorithm is used to decipher the code and extract the k data symbols. In this paper, short length LT codes are generated using efficient sequential encoding approach (SEA) and performance measurements have been done over additive white Gaussian (A WGN) channel. This coding technique generates its degree in a repeated sequential manner which yields a mutual relation between adjacent codes that will be used in the decoding part. The decoding complexity of the proposed structure is similar to that of the Raptor codes. The simulation results show that the proposed approach has better performance in terms of error floor and successful decoding ratio when compared to LT codes using robust soliton distribution (RSD) and memorybased-RSD (MBRSD) even when supported by belief propagation-pattern recognition (BP-PR) technique.
Citation - WoS: 7
Citation - Scopus: 7
A simple analytical EAM model for some bcc metals
(Elsevier, 2010) Dursun, Ibrahim H.; Guvenc, Ziya B.; Kasap, E.; 47800
An analytical embedded atom method which can treat bcc transition metal iron has been developed. In this model, a new potential was presented and a modified term has been introduced to fit the negative Cauchy pressure P-C = (C-12 - C-44)/2 for Fe element. The new model was applied to calculate thermodynamic properties of binary alloys of the bcc transition metals: Fe, V and Cr. The calculated dilute-solution enthalpies and formation enthalpies of random alloys are in good agreement with the results of first principles calculations and that of the thermodynamic calculations. (C) 2009 Elsevier B.V. All rights reserved.
Citation - Scopus: 7
Abstraction-Based Control for Not Necessarily Closed Behaviours
(IFAC Secretariat, 2011) Moor, T.; Schmidt, K.; Wittmann, T.
This paper addresses abstraction-based supervisory control for plant and specification behaviours that are not necessarily ω-closed, i.e. plant behaviours that exhibit eventuality properties and specifications that impose eventuality properties on the closed loop. Technically, the core idea is to combine results from previous work on abstraction-based supervision of input-output behaviours with results on supervisory control of ω-languages. As our main result, we identify a controllability condition for the plant, that ensures a nonblocking closed-loop behaviour with a controller that has been obtained for a plant abstraction. © 2011 IFAC.
Citation - WoS: 110
Citation - Scopus: 112
Active laser radar systems with stochastic electromagnetic beams in turbulent atmosphere
(Optica Publishing Group, 2008) Cai, Yangjian; Korotkova, Olga; Eyyuboglu, Halil T.; Baykal, Yahya; 7688; 7812
Propagation of stochastic electromagnetic beams through paraxial ABCD optical systems operating through turbulent atmosphere is investigated with the help of the ABCD matrices and the generalized Huygens-Fresnel integral. In particular, the analytic formula is derived for the cross-spectral density matrix of an electromagnetic Gaussian Schell-model (EGSM) beam. We applied our analysis for the ABCD system with a single lens located on the propagation path, representing, in a particular case, the unfolded double-pass propagation scenario of active laser radar. Through a number of numerical examples we investigated the effect of local turbulence strength and lens' parameters on spectral, coherence and polarization properties of the EGSM beam. (C) 2008 Optical Society of America
Citation - WoS: 183
Citation - Scopus: 193
Analysis of reciprocity of cos-Gaussian and cosh-Gaussian laser beams in a turbulent atmosphere
(Optical Soc Amer, 2004) Eyyuboglu, HT; Baykal, Y; 7688; 7812
In a turbulent atmosphere, starting with a cos-Gaussian excitation at the source plane, the average intensity profile at the receiver plane is formulated. This average intensity profile is evaluated against the variations of link lengths, turbulence levels, two frequently used free-space optics wavelengths, and beam displacement parameters. We show that a cos-Gaussian beam, following a natural diffraction, is eventually transformed into a cosh-Gaussian beam. Combining our earlier results with the current findings, we conclude that cos-Gaussian and cosh-Gaussian beams act in a reciprocal manner after propagation in turbulence. The rates (paces) of conversion in the two directions are not the same. Although the conversion of cos-Gaussian beams to cosh-Gaussian beams can happen over a wide range of turbulence levels (low to moderate to high), the conversion of cosh-Gaussian beams to cos-Gaussian beams is pronounced under relatively stronger turbulence conditions. Source and propagation parameters that affect this reciprocity have been analyzed. (C) 2004 Optical Society of America.
Citation - WoS: 6
Citation - Scopus: 6
Applications of Cognitive Radio Networks: Recent Advances and Future Directions
(Sage Publications inc, 2016) Kim, Sung W.; Gazi, Orhan; Pan, Miao; Joshi, Gyanendra Prasad; Gazi, Orhan; He, Jianhua; Coupechoux, Marceau; 102896; Elektronik ve Haberleşme Mühendisliği
Citation - WoS: 53
Citation - Scopus: 58
Average intensity and spreading of an elegant Hermite-Gaussian beam in turbulent atmosphere
(Optical Soc Amer, 2009) Yuan, Yangsheng; Cai, Yangjian; Qu, Jun; Eyyuboglu, Halil T.; Baykal, Yahya; 7688; 7812
The propagation of an elegant Hermite-Gaussian beam (EHGB) in turbulent atmosphere is investigated. Analytical propagation formulae for the average intensity and effective beam size of an EHGB in turbulent atmosphere are derived based on the extended Huygens-Fresnel integral. The corresponding results of a standard Hermite-Gaussian beam (SHGB) in turbulent atmosphere are also derived for the convenience of comparison. The intensity and spreading properties of EHGBs and SHGBs in turbulent atmosphere are studied numerically and comparatively. It is found that the propagation properties of EHGBs and SHGBs are much different from their properties in free space, and the EHGB and SHGB with higher orders are less affected by the turbulence. What's more, the SHGB spreads more rapidly than the EHGB in turbulent atmosphere under the same conditions. Our results will be useful in long-distance free-space optical communications. (C) 2009 Optical Society of America
Citation - WoS: 71
Citation - Scopus: 78
Average intensity and spreading of partially coherent standard and elegant Laguerre-Gaussian beams in turbulent atmosphere
(Emw Publishing, 2010) Wang, F.; Cai, Y.; Eyyuboglu, H. T.; Baykal, Y.; 7688; 7812
Analytical expressions for the average intensity, mean-squared beam width and angular spread of partially coherent standard and elegant Laguerre-Gaussian (LG) beams propagating in turbulent atmosphere are derived. The properties of the average intensity, spreading and directionality of partially coherent standard and elegant LG beams in turbulent atmosphere are studied numerically and comparatively. It is found that the beam parameters and structure constant of turbulence together determine the properties of the beams in turbulent atmosphere. Partially coherent standard and elegant LG beams with smaller coherence length, larger beam orders and longer wavelength are less affected by the turbulence. A partially coherent elegant LG beam is less affected by turbulence than a partially coherent standard LG beam under the same condition. Furthermore, it is found that there exist equivalent partially coherent standard and elegant LG beams, equivalent fully coherent standard and elegant LG beams, equivalent Gaussian Schell-model beams that may have the same directionality as a fully coherent Gaussian beam both in free space and in turbulent atmosphere. Our results will be useful in long distance free-space optical communications.
Citation - WoS: 112
Citation - Scopus: 115
Average irradiance and polarization properties of a radially or azimuthally polarized beam in a turbulent atmosphere
(Optical Soc Amer, 2008) Cai, Yangjian; Lin, Qiang; Eyyuboglu, Halil T.; Baykal, Yahya; 7688; 7812
Analytical formulas are derived for the average irradiance and the degree of polarization of a radially or azimuthally polarized doughnut beam (PDB) propagating in a turbulent atmosphere by adopting a beam coherence-polarization matrix. It is found that the radial or azimuthal polarization structure of a radially or azimuthally PDB will be destroyed (i.e., a radially or azimuthally PDB is depolarized and becomes a partially polarized beam) and the doughnut beam spot becomes a circularly Gaussian beam spot during propagation in a turbulent atmosphere. The propagation properties are closely related to the parameters of the beam and the structure constant of the atmospheric turbulence. (C) 2008 Optical Society of America.
Citation - WoS: 5
Citation - Scopus: 5
Bessel Beam Diffraction by an Aperture in an Opaque Screen
(Hindawi Ltd, 2015) Basdemir, Husnu Deniz; Başdemir, Hüsnü Deniz; Elektronik ve Haberleşme Mühendisliği
The scattering of the Bessel beam by a circular aperture in an opaque screen is investigated by the geometrical theory of diffraction approach. The geometrical optics and diffracted and scattered fields are obtained. The effect of the aperture to the scattering process is analyzed. The uniform versions of field expressions are derived. The geometrical optics and diffracted and scattered fields are examined numerically.
Comparative Analysis of Early Studies on Turkish Whistle Language and a Case Study on Test Conditions
(2018) Özaydın, Selma; 253019; Çankaya Meslek Yüksekokulu
This paper examines the early studies on Turkish Whistle Language and it argues that they have some controversial results. The study considers these issues need to be discussed and searched again in terms of linguistic and phonetic form. Unfortunately, there are few research studies on Turkish whistle language and most of them were performed nearly fifty years ago despite the fact that this language still has been used in Kuskoy region. Therefore, the findings of these early research studies could give valuable information to start to a new research study on the subject. The first scientific study on Turkish Whistle language was performed by a French scientist R.G. Busnel with his multidisciplinary research team in 1967. Some of this research’s results were published in the book. A Turkish scientist O. Baskan also participated in Busnel’s research group and published a paper on TWsL in 1968. However, some assertions such as people having a tendency to understand the Turkish whistle language with three vowels and three consonants have not been in the research results of R.G. Busnel. In addition, a Turkish scientist D. Aksan in Turkey had performed another research at Kuskoy region with his own team. Their test methods were different from the previous ones. This paper analyzes these research results on a comparative basis and presents the common and conflicted issues to discuss the uncertain points. The comparative evaluation of these past research studies aims to highlight the controversial position of the results on Turkish Whistle Language. In this scope, this paper opens a discussion about the selection of test conditions for an acoustic and linguistic analysis of the Turkish whistle language.
Citation - WoS: 3
Citation - Scopus: 6
Decoding of LT-like codes in the absence of degree-one code symbols
(Electronics Telecommunications Research inst, 2016) Abdulkhaleq, Nadhir I.; Gazi, Orhan; Gazi, Orhan; 102896; Elektronik ve Haberleşme Mühendisliği
Luby transform (LT) codes were the first practical rateless erasure codes proposed in the literature. The performances of these codes, which are iteratively decoded using belief propagation algorithms, depend on the degree distribution used to generate the coded symbols. The existence of degree-one coded symbols is essential for the starting and continuation of the decoding process. The absence of a degree-one coded symbol at any instant of an iterative decoding operation results in decoding failure. To alleviate this problem, we proposed a method used in the absence of a degree-one code symbol to overcome a stuck decoding operation and its continuation. The simulation results show that the proposed approach provides a better performance than a conventional LT code and memory-based robust soliton distributed LT code, as well as that of a Gaussian elimination assisted LT code, particularly for short data lengths.
Citation - Scopus: 0
Design and Comparison of Vector Quantization Codebooks for Narrowband Speech Coding
(Horizon Research Publishing, 2019) Faraj, H.; Özaydın, Selma; Ozaydin, S.; 253019; Çankaya Meslek Yüksekokulu
Vector quantization codebook algorithms are used for coding of narrow band speech signals. Multi-stage vector quantization and split vector quantization methods are two important techniques used for coding of narrowband speech signals and these methods are very popular due to the high bit rate minimization during coding of the signals. This paper presents performance measurements of multistage vector quantization and split vector quantization methods. We used line spectral frequencies for coding of the speech signals in codebook tables so as to ensure filter stability after quantization. The codebooks were generated by using the Linde-Buzo-Gray (LBG) algorithm. The tests were performed by selecting large amount of input data in training and test stages and to evaluate noise robustness of the methods, both noisy and clean speech signals were used. As a result, different codebooks were designed and tested in many stages and different bit rates to measure quantization performance. It is measured in terms of spectral distortion evaluation. We obtained the best result in 24bit multistage vector quantization codebook with a spectral distortion less than 1 dB for clean speech training data input. When we compared multistage and split vector quantization codebook spectral distortion results, multistage codebooks gave better performance in each option. © 2019 Horizon Research Publishing.
Citation - WoS: 37
Citation - Scopus: 38
Diffraction by a black half plane: Modified theory of physical optics approach
(Optical Soc Amer, 2005) Umul, YZ; Umul, Yusuf Ziya; 42699; Elektronik ve Haberleşme Mühendisliği
The scattered fields from a black half plane which absorbs all the incoming electromagnetic energy are evaluated by defining a new modified theory of physical optics surface current. This current eliminates the reflected fields, coming from the first stationary point of the reflection integral and only creates a reflected diffracted field. The incident scattered fields are found from the same integral, written for the perfectly conducting half plane. The scattered fields are evaluated by using the stationary phase method and edge point technique. The evaluated fields are plotted numerically. (c) 2005 Optical Society of America.
Citation - Scopus: 18
Diffraction theory of waves by resistive surfaces
(Electromagnetics Academy, 2010) Umul, Y.Z.; Umul, Yusuf Ziya; Yalçin, U.; Elektronik ve Haberleşme Mühendisliği
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.
Diffraction Theory of Waves by Resistive Surfaces
(2010) Umul, Yusuf Ziya; Yalçın, Uğur; Elektronik ve Haberleşme Mühendisliği
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.
Citation - WoS: 8
Citation - Scopus: 8
Dynamics of the D(2)+Ni(100) collision system: Analysis of the reactive and inelastic channels
(Wiley-blackwell, 2001) Böyükata, M; Güvenç, ZB; Jackson, B; Jellinek, J
The reactive and scattering channels of the D(2)(v, j) + Ni(100) collision system are studied using quasiclassical molecular dynamics simulations. The interaction between the D(2) and the atoms of the surface is modeled by a LEPS (London-Eyring-Polani-Sato) potential energy function. The molecule is aimed at three different impact sites (atop, bridge, and center) of a rigid Ni(100) surface along the normal direction with various collision energies less than or equal to1.0 eV. Dissociative chemisorption probabilities are computed for different rotational states of the molecule. Probability distributions of the final rovibrational states of the ground-state Dp molecule scattered from those impact sites are also computed as a function of the collision energy. Higher collision energy results in excitation of higher rotational and/or vibrational states of the scattered molecule. At collision energies below 0.1 eV an indirect dissociation mechanism (through molecular adsorption) dominates the reaction. (C) 2001 John Wiley & Sons, Inc.
Citation - WoS: 71
Citation - Scopus: 82
Entropy-Functional-Based Online Adaptive Decision Fusion Framework With Application to Wildfire Detection in Video
(Ieee-inst Electrical Electronics Engineers inc, 2012) Gunay, Osman; Töreyin, Behçet Uğur; Toreyin, Behcet Ugur; Kose, Kivanc; Cetin, A. Enis; 19325; Elektrik-Elektronik Mühendisliği
In this paper, an entropy-functional-based online adaptive decision fusion (EADF) framework is developed for image analysis and computer vision applications. In this framework, it is assumed that the compound algorithm consists of several subalgorithms, each of which yields its own decision as a real number centered around zero, representing the confidence level of that particular subalgorithm. Decision values are linearly combined with weights that are updated online according to an active fusion method based on performing entropic projections onto convex sets describing subalgorithms. It is assumed that there is an oracle, who is usually a human operator, providing feedback to the decision fusion method. A video-based wildfire detection system was developed to evaluate the performance of the decision fusion algorithm. In this case, image data arrive sequentially, and the oracle is the security guard of the forest lookout tower, verifying the decision of the combined algorithm. The simulation results are presented.

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