Elektronik ve Haberleşme Mühendisliği Bölümü Yayın Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/260

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Citation Count: Rafiq, Muhammad...et al. (2020). "A reliable and competitive mathematical analysis of Ebola epidemic model", Advances in Difference Equations, Vol. 2020, No. 1.
A reliable and competitive mathematical analysis of Ebola epidemic model
(2020) Rafiq, Muhammad; Ahmad, Waheed; Abbas, Mujahid; Baleanu, Dumitru; 56389
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.
Citation Count: Abdulkhaleq, Nadhir Ibrahim; Gazi, Orhan (2017). "A Sequential Coding Approach for Short Length LT Codes over A WGN Channel",
A Sequential Coding Approach for Short Length LT Codes over A WGN Channel
(2017) Abdulkhaleq, Nadhir Ibrahim; Gazi, Orhan
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 Count: Umul, Yusus Ziya, "A survey of the new proposal about the photon momentum", Optik, Vol.148, pp.342-343, (2017).
A survey of the new proposal about the photon momentum
(Elsevier GMBH, 2017) Umul, Yusuf Ziya; 42699
Bahadoran et al. [1] proposed that the new approach to photon momentum, introduced by Umul [2], was not correct, because they obtained a negative energy expression for the absorbed photon. In this comment, we show that this proposal is wrong, since the related authors made a mistake in their derivations.
Citation Count: Moor, T.; Schmidt, K.; Wittmann, T., "Abstraction-Based Control for Not Necessarily Closed Behaviours", Ifac Proceedings Volumes (Ifac-Papersonline), Vol. 44, No. 1-1, pp. 6988-6993, (2011).
Abstraction-Based Control for Not Necessarily Closed Behaviours
(IFAC Secretariat, 2011) Moor, Thomas; Schmidt, Klaus Werner; Wittmann, Thomas
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.
Citation Count: Cai, Y., Korotkova, O., Eyyuboğlu,H.T., Baykal, Y. (2008). Active laser radar systems with stochastic electromagnetic beams in turbulent atmosphere. Optics Express, 16(20), 15834-15846. http://dx.doi.org/10.1364/OE.16.015834
Active laser radar systems with stochastic electromagnetic beams in turbulent atmosphere
(Optical Soc Amer, 2008) Cai, Yangjian; Korotkova, Olga; Eyyuboğlu, 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
Citation Count: Baykal, Yahya, "Adaptive Optics Correction of Scintillation in Underwater Medium", Journal of Modern Optics, Vol. 67, No. 3, pp. 220-225, (2020).
Adaptive Optics Correction of Scintillation in Underwater Medium
(Taylor&Francis LTD, 2020) Baykal, Yahya; 7812
Adaptive 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.
Citation Count: Eyyuboğlu, Halil T.; Baykal, Y., "Analysis of reciprocity of cos-Gaussian and cosh-Gaussian laser beams in a turbulent atmosphere", Optics, Express, Vol.12, No.20, pp.4659-4674, (2004).
Analysis of reciprocity of cos-Gaussian and cosh-Gaussian laser beams in a turbulent atmosphere
(Optical Soc Amer, 2004) Eyyuboğlu, Halil T.; Baykal, Yahya; 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.
Citation Count: Gökçe, M.C...et al. (2015). Aperture averaging in multiple-input single-output free-space optical systems. Optical Engineering, 54(6). http://dx.doi.org/10.1117/1.OE.54.6.066103
Aperture averaging in multiple-input single-output free-space optical systems
(Spie-Soc Photo-Optical Instrumentation Engineers, 2015) Gökçe, Muhsin Caner; Baykal, Yahya; Kamacıoğlu, Canan; Uysal, Murat; 28643; 7812; 124615
Multiple-input single-output systems are employed in free-space optical links to mitigate the degrading effects of atmospheric turbulence. We formulate the power scintillation as a function of transmitter and receiver coordinates in the presence of weak atmospheric turbulence by using the extended Huygens Fresnel principle. Then the effect of the receiver aperture averaging is quantified. To get consistent results, parameters are chosen within the range of validity of the wave structure functions. Radial array beams and a Gaussian weighting aperture function are used at the transmitter and the receiver, respectively. It is observed that the power scintillation decreases when the source size, the ring radius, the receiver aperture radius, and the number of array beamlet increase. However, increasing the number of array beamlets to more than three seems to have negligible effect on the power scintillation. It is further observed that the aperture averaging effect is stronger when radial array beams are employed instead of a single Gaussian beam.
Citation Count: Umul, Yusuf Ziya,"Application of the Method of Transition Boundary To the Half-Planes With Mixed Boundary Conditions",Optik, Vol. 205, (2020).
Application of the Method of Transition Boundary To the Half-Planes With Mixed Boundary Conditions
(Elsevier GMBH, 2020) Umul, Yusuf Ziya; 42699
The scattering problems of waves by soft-hard and hard-soft half-planes are investigated by the method of transition boundary. The functional values at the transition boundaries are found to be identical to the ones for the soft and hard half-screens. It is shown that the factorization process should be applied by also taking into account the boundary conditions besides the principle of reciprocity. The exact diffracted field expressions are obtained for both of the half-planes.
Citation Count: Kim, Sung W...et al., "Applications of Cognitive Radio Networks: Recent Advances and Future Directions", International Journal of Distributed Sensor Networks, (2016).
Applications of Cognitive Radio Networks: Recent Advances and Future Directions
(Sage Publications LTD, 2016) Kim, Sung W.; Pan, Miao; Joshi, Gyanendra Prasad; Gazi, Orhan; He, Jianhua; Coupechoux, Marceau; 102896
Citation Count: Yuan, Y...et al. (2009). Average intensity and spreading of an elegant Hermite-Gaussian beam in turbulent atmosphere. Optics Express, 17(13), 11130-11139. http://dx.doi.org/10.1364/OE.17.011130
Average intensity and spreading of an elegant Hermite-Gaussian beam in turbulent atmosphere
(Optical Soc Amer, 2009) Yuan, Yangsheng; Cai, Yangjian; Qu, Jun; Eyyuboğlu, 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
Citation Count: Cai, Y...et al. (2008). Average irradiance and polarization properties of a radially or azimuthally polarized beam in a turbulent atmosphere. Optics Express, 16(11), 7665-7673. http://dx.doi.org/10.1364/OE.16.007665
Average irradiance and polarization properties of a radially or azimuthally polarized beam in a turbulent atmosphere
(Optical Society of America, 2008) Cai, Yangjian; Qiang, Lin; Eyyuboğlu, 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
Citation Count: Bessel Beam Diffraction by an Aperture in an Opaque Screen By:Basdemir, HD (Basdemir, Husnu Deniz)[ 1 ]
Bessel Beam Diffraction by an Aperture in an Opaque Screen
(2015) Başdemir, Hüsnü Deniz
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. Keywords
Citation Count: Arpali, S.A.: Arpali, Ç.; Baykal, Y.,"Bit Error Rate of A Gaussian Beam Propagating Through Biological Tissue",Journal of Modern Optics, Vol. 67, No. 4, pp. 340-345, (2019).
Bit Error Rate of A Gaussian Beam Propagating Through Biological Tissue
(Bit Error Rate of A Gaussian Beam Propagating Through Biological Tissue, 2020) Altay Arpalı, Serap; Arpalı, Çağlar; Baykal, Yahya; 7812; 51304; 20809
The 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. © 2020, © 2020 Informa UK Limited, trading as Taylor & Francis Group.
Citation Count: Basdemir, H.D.,"Comment On 'Fringe Waves in An Impedance Half-Plane'",Progress in Electromagnetics Research Letters, Vol. 46, pp. 83-83, (2018).
Comment On 'Fringe Waves in An Impedance Half-Plane'
(Electromagnetics Acad, 2014) Başdemir, Hüsnü Deniz; 20399
Citation Count: Özaydın, Selma. (2018). "Comparative Analysis of Early Studies on Turkish Whistle Language and a Case Study on Test Conditions", Open Journal of Modern Linguistics, No.8, pp.126-136.
Comparative Analysis of Early Studies on Turkish Whistle Language and a Case Study on Test Conditions
(2018) Özaydın, Selma; 253019
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 Count: Umul, Y.Z.,"Comparison of Diffraction Methods for Lunar Occultations",Optik, Vol. 205, (2020).
Comparison of Diffraction Methods for Lunar Occultations
(Elsevier GMBH, 2020) Umul, Yusuf Ziya; 42699
The only analytical method, which is used for the mathematical analysis of lunar occultations, is the Fresnel diffraction. The Fresnel integral is derived from the diffraction integral of Kirchhoff under some approximations. This paper aims to compare this method with the exact solution of Sommerfeld, which is obtained for a perfect electric conductor half-plane. The geometrical optics and diffracted fields are expressed separately. Numerical simulations are given for the comparison of two different total and diffracted waves.
Citation Count: Baykal, Y. (2014). Crossbeam intensity fluctuations in turbulence. Optical Engineering, 53(5). http://dx.doi.org/10.1117/1.OE.53.5.055105
Crossbeam intensity fluctuations in turbulence
(Spie-Soc Photo-Optical Instrumentation Engineers, 2014) Baykal, Yahya; 7812
Intensity fluctuations of a crossbeam are evaluated in weak atmospheric turbulence. A crossbeam is defined as two asymmetrical Gaussian beams oriented perpendicular to each other, and one of these beams is wider along the x-axis whereas the other beam is wider along the y-axis. Our results indicate that in terms of the intensity fluctuations in weak turbulence, focused crossbeams offer favorable results when compared to the corresponding focused Gaussian beam intensity fluctuations. However, for collimated crossbeams, such a comparison is in favor of the collimated Gaussian beam
Citation Count: Abdulkhaleq, N.I., Gazi, O. (2016). Decoding of LT-like codes in the absence of degree-one code symbols. Etri Journal, 38(5), 896-902. http://dx.doi.org/10.4218/etrij.16.0116.0107
Decoding of LT-like codes in the absence of degree-one code symbols
(Electronics Communications Research Inst., 2016) Abdulkhaleq, Nadhir Ibrahim; Gazi, Orhan; 102896
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 Count: Faraj, H.; Ozaydin, S., "Design and Comparison of Vector Quantization Codebooks for Narrowband Speech Coding", Universal Journal of Electrical and Electronic Engineering, Vol. 6, No. 3, pp. 139-146, (2019).
Design and Comparison of Vector Quantization Codebooks for Narrowband Speech Coding
(Horizon Research Publishing, 2019) Faraj, Hiba; Özaydın, Selma; 253019
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.

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