Elektronik ve Haberleşme Mühendisliği Bölümü

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Citation Count: Al-Mihrab, M...at all (2020). "A compact size multiband printed monopole antenna with triple sense circular polarization for wireless applications", Journal of Optoelectronics and Advanced Materials, Vol. 22, No. 9-10, pp. 483-494.
A compact size multiband printed monopole antenna with triple sense circular polarization for wireless applications
(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.
Citation Count: Yıldırım, E.K., Güvenç. Z.B. (2009). A density functional study of small Li-B and Li-B-H clusters. International Journal of Hydrogen Energy , 34(11), 4797-4816. http://dx.doi.org/10.1016/j.ijhydene.2009.03.051
A density functional study of small Li-B and Li-B-H clusters
(Pergamon-Elsevier Science Ltd, 2009) Yıldırım, Erdem Kamil; Güvenç, Büşra; 1155
In this work we present the results of a detailed theoretical research for the small Li(n)B(m) clusters and their hydrogen storage properties by means of density functional theory. All calculations were performed by using Gaussian03 program. For the optimization of the clusters 6-311++G(d,p) basis set was employed. We have chosen global minimum of B(6) cluster as the starting point and replaced the boron atoms one at a time, in a stepwise manner, with Li atoms. For these new structures we have searched for the stable configurations, and calculated their energies, HOMO-LUMO energy gaps, Raman and infrared data, average boron, and lithium charge distribution, and vibrational frequencies. Our results show that as the number of Li atoms increases, stability of the clusters decreases and they become more reactive. In addition to that, there are significant charge transfers from boron atoms to lithium atoms on average. The hydrogen storage capabilities of the most stable isomers of Li(n)B(m) and B(6) clusters have also been investigated by the same methods, and the results are compared. The Li(3)B(3) has the highest hydrogen storage capacity among the clusters investigated in this study. Furthermore, formation of hydrogen molecules is observed in the vicinity of the clusters, some of which are attached to the Li atoms. In addition, as the number of hydrogen atoms increases, the boron atoms are separated from the other boron atoms, and they form satellite BH(x) (x = 3,4) clusters around the center. These are attached to the system by a bridging bond of a hydrogen or a Li atom
Citation Count: Umul, Y.Z. (2011). A hybrid Maliuzhinets/PO method for diffraction problems by impedance wedges. Optic Communications, 284(19), 4289-4294. http://dx.doi.org/10.1016/j.optcom.2011.06.045
A hybrid Maliuzhinets/PO method for diffraction problems by impedance wedges
(Elsevier Science Bv, 2011) Umul, Yusuf Ziya; 42699
The solution of Maliuzhinets of the diffraction problem of waves by an impedance wedge is transformed into a physical optics integral. The resultant expression is suitable for the investigation of various diffraction problems having impedance wedges. The method is applied to the scattering of waves by an impedance spherical reflector with wedge structure at its discontinuity. The results are examined numerically.
Citation Count: Saraçoğlu, Kıvanç; Üleş, Buğra; Schmidt, Klaus Werner (2018). "A Lane Keeping System with a Weighted Preview Measurement", 2018 26TH SIGNAL PROCESSING AND COMMUNICATIONS APPLICATIONS CONFERENCE (SIU).
A Lane Keeping System with a Weighted Preview Measurement
(2018) Saraçoğlu, Kıvanç; Üleş, Buğra; Schmidt, Klaus Werner
This paper proposes a new lane keeping system (LKS) based on a weighted preview measurement. The paper first identifies shortcomings of existing methods that use the sole measurement of lateral displacement error at a preview distance or at the center of gravity. Then, the novel idea of computing a weighted average of both measurements is proposed. The stability of the resulting LKS is analyzed and the improved performance of the resulting LKS is supported by simulation experiments.
Citation Count: Şener, G. (2013). A new algorithm to locate the zero fields in antenna radiation pattern measurements. Journal Of Electromagnetic Waves And Applications, 27(10), 1238-1245. http://dx.doi.org/10.1080/09205071.2013.805169
A new algorithm to locate the zero fields in antenna radiation pattern measurements
(Taylor&Francis Ltd, 2013) Şener, Göker; 17740
This article describes a new method to determine the directions of the zero fields in antenna radiation measurements. Zero-field detection is important when there are null constraints in antenna analysis or synthesis. To identify the directions of the zero fields, the general practice is to measure the propagating field in a number of small incremental angles in 2D space. For an antenna with narrow beam characteristics, even more sampling is necessary for accuracy. As a result, the time efficiency is decreased. In order to speed up the process, an optimization algorithm may be employed such that the measurements may converge to the zero-field locations faster. However, the difficulty is that many optimization algorithms require the use of derivatives of the pattern function. The algorithm proposed in this paper is derivative free and utilizes only the amplitude data, hence it is suitable and applicable to antenna measurements providing time efficiency.
Citation Count: Umul, Yusuf Ziya, "A new approach to the Dirac equation", Optik, Vol. 181, pp. 524-527, (2019).
A new approach to the Dirac equation
(Elsevier GMBH, 2019) Umul, Yusuf Ziya; 42699
Dirac equation is based on a novel method that expresses the roots of a square-root operation in terms of matrices. Instead of this technique we propose an alternative approach. The square-root expression is represented as a hypotenuse and it is written in terms of a trigonometric summation of the remaining two edges of a right-angle triangle. Both of the positive and negative energy terms are taken into account and a new matrix equation is obtained. The plane wave solutions of the new differential equation are studied.
Citation Count: Gazi, Orhan. "A New Companding Technique for Papr Reduction in Ofdm Communication Systems", International Congress On Ultra Modern Telecommunications and Control Systems And Workshops, (2011).
A New Companding Technique for Papr Reduction in Ofdm Communication Systems
(2011) Gazi, Orhan; 102896
One of the major disadvantages of OFDM communication systems is their high peak-to-average power ratio (PAPR) which degrades system performance when nonlinear power amplifiers are employed. Among the proposed PAPR techniques companding is favorable due to its simplicity and easy of implementation. In this article, using the arctangent function we propose a new compading technique for PAPR reduction. We compare the proposed technique to the previously suggested exponential companding, and μ-law companding methods. Via computer simulations it is verified that the proposed technique is better than exponential and μ-law companding methods for PAPR reduction.
Citation Count: Mezaal, Y.S.; Eyyuboglu, Halil T.; Ali, J.K., "A New Design of Dual Band Microstrip Bandpass Filter Based On Peano Fractal Geometry: Design and Simulation Results", Mediterranean Microwave Symposium, (2013).
A New Design of Dual Band Microstrip Bandpass Filter Based On Peano Fractal Geometry: Design and Simulation Results
(2013) Mezaal, Yaqeen S.; Eyyuboğlu, Halil T.; Ali, Jawad 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.
Citation Count: Sermutlu, E., Eyyuboğlu, H:T: (2007). A new quadrature routine for improper and oscillatory integrals. Applied Mathematics&Computation, 189(1), 452-461. http://dx.doi.org/10.1016/j.amc.2006.08.176
A new quadrature routine for improper and oscillatory integrals
(Elsevier Science, 2007) Sermutlu, Emre; Eyyuboğlu, Halil T.; 17647; 7688
In MATLAB environment, a new quadrature routine based on Gaussian quadrature rule has been developed. Its performance is evaluated for improper integrals, rapidly oscillating functions and other types of functions requiring a. large number of evaluations. This performance is compared against the other quadrature routines written for MATLAB in terms of capability, accuracy and computation time. It is found that our routine rates quite favourably
Citation Count: Umul, Y.Z. (2013). A new representation of the Kirchhoffs diffraction integral. Optic Communications, 291 48-51. http://dx.doi.org/10.1016/j.optcom.2012.11.038
A new representation of the Kirchhoffs diffraction integral
(Elsevier Science Bv, 2013) Umul, Yusuf Ziya; 42699
The diffraction integral of Kirchhoff is rearranged according to its integral boundaries. The new approach is based on the theory of the edge dislocation waves and provides a more correct field representation for the semi-infinite and infinite integrals in the direct numerical computation. The integral is studied on the diffraction problem of plane waves by a perfectly conducting half-plane. The correctness of the scattering diagrams is compared with the classical approach and the Fresnel integral representation of the scattered waves numerically
Citation Count: Umul, Yusuf Ziya (2021). "A new series solution associated with the quantum harmonic oscillator", Optik, Vol. 25.
A new series solution associated with the quantum harmonic oscillator
(2021) Umul, Yusuf Ziya; 42699
In the non-relativistic case, the problem of quantum harmonic oscillator is solved by the aid of the Schro spacing diaeresis dinger equation. An additional term of potential energy that is related with the square of the spatial coordinate is also included in the equation. A second order linear differential equation is obtained in the stationary state. The direct solution gives the wave function in terms of the parabolic cylinder functions. This solution leads to the Hermite polynomials when the quantization of energy is considered. However, the derived expression of the wave function does not yield the correct functions for the limiting case, in which the potential energy is zero. We put forth an alternative solution for the second order linear differential equation. First of all, a new series expression is suggested as an ansatz for the power series solution of differential equations. The coefficients of the series are obtained in terms of recurrence relations. Some computational simulations are given.
Citation Count: Mezaal, Yaqeen S.; Eyyuboglu, Halil T.; Ali, Jawad K. "A Novel Design of Two Loosely Coupled Bandpass Filter Based on Hilbert-zz Resonator with Higher Harmonic Suppression", 2013 Third International Conference On Advanced Computing & Communication Technologies (Acct 2013), pp. 343-347, (2013).
A Novel Design of Two Loosely Coupled Bandpass Filter Based On Hilbert-Zz Resonator With Higher Harmonic Suppression
(IEEE, 2013) Mezaal, Yaqeen S.; Eyyuboğlu, Halil T.; Ali, Jawad K.; 7688
New characteristics of fractal design scheme has been introduced to generate compact two poles capacitively coupled microstrip bandpass filter by using additional coupling stubs for different wireless applications. The presented fractal scheme is based on specific type of Hilbert space-filling curve which is called Hilbert-zz fractal geometry. The performance of generated bandpass filter structure has been analyzed using Sonnet software package with a relative dielectric constant of 9 and a substrate thickness of 1.27 mm. Results show that these filters possess good transmission and return loss characteristics, besides higher harmonics suppressions; meeting the specifications of most of wireless communication systems.
Citation Count: Humada, A.M...et al. "A Proposed Method of Photovoltaic Solar Array Configuration Under Different Partial Shadow Conditions", Advanced Materials Research, Vol 933, pp. 307-311, (2014).
A Proposed Method of Photovoltaic Solar Array Configuration Under Different Partial Shadow Conditions
(Trans Tech Publications LTD, 2014) Humada, Ali Mahmood; Hojabri, Mojgan; Mohamed, Mortaza B.; Herwan Bin Sulaiman, Mohd; Dakheel, Taha Hamad
The benefit of improving the efficiency of photovoltaic (PV) solar system has come into view because of increasing the demand for electricity, especially in the urban areas. However, these PV solar systems are vulnerable to the mismatch operating conditions. Under such conditions, the performance of solar cells has decreased rapidly since the nonuniform insolation hitting the cells and with different values. Then this leads to cause rapidly decreasing in the output power value and maximum power point, beside to hot spot points that may be occurring in the solar cell which finally leads to damage these cells. This paper proposes an optimal connection of substrings with different value of shadow conditions, based on a thorough configuration that can significantly reduce that nonuniform condition loss. The refinement over existing photovoltaic (PV) solar array interconnections is proven by extensive simulation results by using MATLAB SIMULINK
Citation Count: Umul, Yusuf Ziya (2021). "A relativistic electron interacting with electromagnetic waves", Optik, Vol. 231.
A relativistic electron interacting with electromagnetic waves
(2021) Umul, Yusuf Ziya; 42699
A relativistic electron, in an electromagnetic wave is studied. The relativistic energy-momentum relation is taken into consideration for the derivation of a wave equation for spin-1/2 particle. The electromagnetic wave is represented by the electric scalar and magnetic vector potentials. Thus the spin information of the electron is integrated into the relativistic differential equation. A relativistic quantum wave equation is derived by using the derivatives with respect to time and spatial coordinates with respect to the kinetic energy and momentum of the electron. It is shown that the obtained relativistic equation directly reduces to the Pauli equation in the non-relativistic limit.
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: Abdulkhaleq, Nadhir Ibrahim; Gazi, Orhan, "A sequential coding approach for short length lt codes over awgn channel", 2017 4th International Conference On Electrical And Electronic Engineering (ICEEE 2017), pp. 267-271, (2017).
A sequential coding approach for short length lt codes over awgn channel
(IEEE, 2017) Abdulkhaleq, Nadhir Ibrahim; Gazi, Orhan; 102896
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 (AWGN) 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 memory-based-RSD (MBRSD) even when supported by belief propagation-pattern recognition (BP-PR) technique.
Citation Count: Dursun, H.D., Güvenç, Z.B., Kasap, E. (2010). A simple analytical EAM model for some bcc metals. Communications In Nonlinear Science And Numerical Simulation, 15(5), 1259-1266. http://dx.doi.org/10.1016/j.cnsns.2009.05.034
A simple analytical EAM model for some bcc metals
(Elsevier Science Bv, 2010) Dursun, İbrahim H.; Güvenç, 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.
Citation Count: Eyyuboğlu, H.T. (2008). A study of source plane Mathieu beams. Applied Physisc B-Lasers And Optics, 91(3-4), 629-637. http://dx.doi.org/10.1007/s00340-008-3046-y
A study of source plane Mathieu beams
(Springer, 2008) Eyyuboğlu, Halil T.; 7688
We derive the source field expressions of different Mathieu beams. In particular, Mathieu beams consisting of the infinite summations of J-type Bessel functions and their Gaussian counterparts are studied. Mathieu beams based on the summation of I-type Bessel functions are introduced as well. By plotting the source intensities of such beams, the variations of the related profiles are examined against the changes in the source parameters. It is found that, via the adjustment of these parameters, it is possible to obtain completely new beam configurations and also those similar to the existing beams of the present literature
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.

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