Browsing by Author "Eyyuboglu, Halil Tanyer"

Now showing 1 - 14 of 14

Citation - WoS: 7
Citation - Scopus: 11
Effect of Source Spatial Partial Coherence on the Angle-Of Fluctuations for Free-Space Optics Links
(Spie-soc Photo-optical instrumentation Engineers, 2006) Baykal, Yahya; Eyyuboglu, Halil Tanyer; 7812; 7688; 06.03. Elektrik-Elektronik Mühendisliği; 06.02. Elektronik ve Haberleşme Mühendisliği; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
The dependence of angle-of-arrival fluctuations on source coherence for free-space optics links in a turbulent atmosphere is examined. A monochromatic beam is taken, and the variation of the angle-of-arrival fluctuations for a spatially partially coherent source is investigated. Results are obtained for the currently used free-space optics links, which use infrared wavelengths of 0.85 and 1.55 mu m with link lengths of 3 and 5 km. The angle-of-arrival fluctuations are calculated and plotted against normalized source size and inner and outer scales of turbulence. It is observed that the angle-of-arrival fluctuations show behavior that is essentially independent of the degree of source partial coherence. In fact, as the source size increases, this dependence seems to almost disappear. It is further observed that mean square angle-of-arrival fluctuations become larger at greater propagation distances, at smaller inner scales of turbulence, and at larger outer scales of turbulence. However, the numerical values of the angle-of-arrival fluctuations found for all cases are not expected to degrade substantially the performance of a practical optical receiver having a field of view in the order of several milliradians. Our results presented here are compared with the existing theoretical and experimental work, and the range of applicability of our formulation is discussed. (C) 2006 Society of Photo-Optical Instrumentation Engineers.
Citation - WoS: 136
Citation - Scopus: 135
Flat Topped Beams and Their Characteristics in Turbulent Media
(Optical Soc Amer, 2006) Eyyuboglu, Halil Tanyer; Arpali, Caglar; Baykal, Yahya Kemal; 7688; 7812; 06.02. Elektronik ve Haberleşme Mühendisliği; 06.08. Mekatronik Mühendisliği; 06.03. Elektrik-Elektronik Mühendisliği; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
The source and receiver plane characteristics of flat topped ( FT) beam propagating in turbulent atmosphere are investigated. To this end, source size, beam power and M(2) factor of source plane FT beam are derived. For a turbulent propagation medium, via Huygens Fresnel diffraction integral, the receiver plane intensity is found. Power captured within an area on the receiver plane is calculated. Kurtosis parameter and beam size variation along the propagation axis are formulated. Graphical outputs are provided displaying the variations of the derived source and receiver plane parameters against the order of flatness and propagation length. Analogous to free space behavior, when propagating in turbulence, the FT beam first will form a circular ring in the center. As the propagation length increases, the circumference of this ring will become narrower, giving rise to a downward peak emerging from the center of the beam, eventually turning the intensity profile into a pure Gaussian shape. (c) 2006 Optical Society of America.
Citation - WoS: 10
Citation - Scopus: 11
Generalized Beams in Abcdgh Systems
(Elsevier Science Bv, 2007) Eyyuboglu, Halil Tanyer; Baykal, Yahya; 7688; 7812; 06.02. Elektronik ve Haberleşme Mühendisliği; 06.03. Elektrik-Elektronik Mühendisliği; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
For a generalized beam at the source plane passing through co-located aperture and a propagation path consisting of an off-axis x-y asymmetric ABCDGH system, the receiver plane irradiance expression is derived using the Collins integral. A collection of source beam profiles that are obtainable from the generalized. beam formulation are illustrated. Plots are given for viewing the progress of selected generalized beam types along the propagation axis, containing a single thin lens, co-centric and misaligned in the x-direction. The received power failing onto a finite aperture surface is calculated for various misalignment situations. (c) 2006 Elsevier B.V. All rights reserved.
Citation - WoS: 7
Citation - Scopus: 8
Hermite Hyperbolic/Sinusoidal Gaussian Beams in Abcd Systems
(Elsevier Gmbh, 2007) Eyyuboglu, Halil Tanyer; 7688; 06.02. Elektronik ve Haberleşme Mühendisliği; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
For a Hermite hyperbolic/sinusoidal Gaussian beam with focusing properties, passing through an arbitrarily shaped rectangular aperture on the source plane and an on-axis x-y asymmetric ABCD system, the receiver plane expression is derived using the Collins integral. The specific example of a single thin lens placed on the propagation path is examined at selected source, propagation and optical element parameters. Viewing the progress of the beam in propagation, we find that subjecting the source beam to an aperture will give rise to excessive spreading during propagation. The lens setup will act to concentrate the energy of the beam around its focal point as expected, while in some circumstances it will also execute beam profile changes. By adjusting the aperture opening in the shape of a narrow slit, the beam will become aligned in the opposite direction after propagating after having traveled sufficiently. The results are presented as intensity graphs in the form of contour plots and 3D illustrations. (c) 2006 Elsevier GmbH. All rights reserved.
Citation - WoS: 15
Citation - Scopus: 19
Hypergeometric Gaussian Beam and Its Propagation in Turbulence
(Elsevier Science Bv, 2012) Eyyuboglu, Halil Tanyer; Cai, Yangjian; 7688; 06.02. Elektronik ve Haberleşme Mühendisliği; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
We study propagation characteristics of hypergeometric Gaussian beam in turbulence. In this context, we formulate the receiver plane intensity using extended Huygens-Fresnel integral. From the graphical results, it is seen that, after propagation, hypergeometric Gaussian will in general assume the shape of a dark hollow beam at topological charges other than zero. Increasing values of topological charge will make the beam broader with steeper walls. On the other hand, higher values of hollowness parameter will contract into a narrower shape. Raising the topological charge or the hollowness parameter individually will cause outer rings to appear. Both increased levels of turbulence and longer propagation distances will accelerate the beam evolution and help reach the final Gaussian shape sooner. At lower wavelengths, there will be less beam spreading. (C) 2012 Elsevier B.V. All rights reserved.
Influence of Atmospheric Turbulence on Quality of Multichannel Laser Radiation and Correction for Distortion
(Spie-int Soc Optical Engineering, 2016) Kanev, F. Yu.; Lukin, V. P.; Makenova, N. A.; Antipov, O. L.; Eyyuboglu, Halil Tanyer; 7688; 06.02. Elektronik ve Haberleşme Mühendisliği; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
In this paper the results of simulation are presented of multichannel radiation propagation in the atmosphere, and correction for turbulent distortion on the base of the beam phase control is considered. The results demonstrate dependence of correction effectiveness on number of channels and on precision of a reference beam phase reconstruction. Additionally increase of effectiveness is possible with adjustment of amplification in the channels of the optical system, i.e., with the use of amplitude-phase control of radiation.
Citation - WoS: 2
Citation - Scopus: 4
An Intelligent System for Detecting Mediterranean Fruit Fly [Medfly; Ceratitis Capitata (Wiedemann)]
(Pagepress Publ, 2022) Eyyuboglu, Halil Tanyer; Sari, Filiz; Uzun, Yusuf; Tolun, Mehmet Resit; 06.02. Elektronik ve Haberleşme Mühendisliği; 06.09. Yazılım Mühendisliği; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
Nowadays, the most critical agriculture-related problem is the harm caused to fruit, vegetable, nut, and flower crops by harmful pests, particularly the Mediterranean fruit fly, Ceratitis capitata, named Medfly. Medfly's existence in agricultural fields must be monitored systematically for effective combat against it. Special traps are utilised in the field to catch Medflies which will reveal their presence and applying pesticides at the right time will help reduce their population. A technologically supported automated remote monitoring system should eliminate frequent site visits as a more economical solution. This paper develops a deep learning system that can detect Medfly images on a picture and count their numbers. A particular trap equipped with an integrated camera that can take photos of the sticky band where Medflies are caught daily is utilised. Obtained pictures are then transmitted by an electronic circuit containing a SIM card to the central server where the object detection algorithm runs. This study employs a faster region-based convolutional neural network (Faster R-CNN) model in identifying trapped Medflies. When Medflies or other insects stick on the trap's sticky band, they spend extraordinary effort trying to release themselves in a panic until they die. Therefore, their shape is badly distorted as their bodies, wings, and legs are buckled. The challenge is that the deep learning system should detect these Medflies of distorted shape with high accuracy. Therefore, it is crucial to utilise pictures containing trapped Medfly images with distorted shapes for training and validation. In this paper, the success rate in identifying Medflies when other insects are also present is approximately 94%, achieved by the deep learning system training process, owing to the considerable amount of purpose-specific photographic data. This rate may be seen as quite favourable when compared to the success rates provided in the literature.
Citation - WoS: 1
Matlab Simulation of Multiuser Detection in Cdma
(World Acad Sci, Eng & Tech-waset, 2005) Eyyuboglu, Halil Tanyer; 06.02. Elektronik ve Haberleşme Mühendisliği; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
This paper describes the MATLAB simulation of multiuser detection in code division multiple access (CDMA). To reach low bit error rate (BER) levels within reasonable computation times, the method of importance sampling is utilized. Our design is based on the step by step practical implementation of matched filter (MF) detection, has therefore the flexibility of variations in all parameters of interest which are otherwise difficult to accommodate in a theoretical model. Our initial findings are compared and verified against theoretical predictions and against those available in the literature.
Citation - WoS: 5
Citation - Scopus: 31
A New Narrow Band Dual-Mode Microstrip Slotted Patch Bandpass Filter Design Based on Fractal Geometry
(Ieee, 2012) Eyyuboğlu, Halil Tanyer; Mezaal, Yaqeen S.; Eyyuboglu, Halil Tanyer; 7688; Elektronik ve Haberleşme Mühendisliği; 06.02. Elektronik ve Haberleşme Mühendisliği; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
A narrowband, compact, and easily fabricated microstrip bandpass filter design is introduced in this paper as a candidate for use in modern wireless systems. The proposed filter design is based on the use of dual-mode (two pole) square slotted microstrip resonator. This microstrip bandpass filter has the advantages of possessing much narrower and sharper performance responses than those of the single mode resonator and conventional square patch filter. The proposed microstrip filter structure is fractally generated using Sierpinski fractal curve geometry applied to the conventional square microstrip patch. Filter structures resulting from the successive iterations in the fractal generation process show a considerably low insertion loss, and sharper response of about 1% fractional bandwidth as compared with the conventional microstrip square patch filter of 3% fractional bandwidth designed at the same frequency using the same substrate material. The performance of filter structures, based on dual-mode resonators up to the third iterations, has been evaluated using a full-wave based electromagnetic simulator Sonnet software package. Performance simulation results show that these filter structures offer narrower fractional bandwidth percentages as compared with other types of non- fractalized filter structures.
Propagation of a Generalized Beam in Abcd System
(World Acad Sci, Eng & Tech-Waset, 2005) Eyyuboglu, Halil Tanyer; 7688; Elektronik ve Haberleşme Mühendisliği; 06.02. Elektronik ve Haberleşme Mühendisliği; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
For a generalized Hermite sinosiodal/hyperbolic Gaussian beam passing through an ABCD system with a finite aperture, the propagation properties are derived using the Collins integral. The results are obtained in the form of intensity graphs indicating that previously demonstrated rules of reciprocity are applicable, while the existence of the aperture accelerates this transformation.
Citation - WoS: 38
Citation - Scopus: 44
Propagation of Modified Bessel-Gaussian Beams in Turbulence
(Elsevier Sci Ltd, 2008) Eyyuboglu, Halil Tanyer; Hardalac, Firat; 7688; 06.02. Elektronik ve Haberleşme Mühendisliği; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
We investigate the propagation characteristics of modified Bessel-Gaussian beams traveling in a turbulent atmosphere. The source beam formulation comprises a Gaussian exponential and the summation of modified Bessel functions. Based on an extended Huygens-Fresnel principle, the receiver plane intensity is formulated and solved down to a double integral stage. Source beam illustrations show that modified Bessel-Gaussian beams, except the lowest order case, will have well-like shapes. Modified Bessel-Gaussian beams with summations will experience lobe slicing and will display more or less the same profile regardless of order content. After propagating in turbulent atmosphere, it is observed that a modified Bessel-Gaussian beam will transform into a Bessel-Gaussian beam. Furthermore it is seen that modified Bessel-Gaussian beams with different Bessel function combinations, but possessing nearly the same profile, will differentiate during propagation. Increasing turbulence strength is found to accelerate the beam transformation toward the eventual Gaussian shape. (c) 2007 Elsevier Ltd. All rights reserved.
Citation - WoS: 13
Citation - Scopus: 13
Propagation Properties of Optical Bottle Beam in Turbulence
(Spie-soc Photo-optical instrumentation Engineers, 2019) Eyyuboglu, Halil Tanyer; Bayraktar, Mert; 53038; 06.02. Elektronik ve Haberleşme Mühendisliği; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
We study the propagation properties of optical bottle beams in turbulent atmosphere. By allowing the mathematical expression of source plane to cover both the symmetric and asymmetric forms, the beam is propagated through turbulence using random phase screens. On the source plane, the intensity profile of the bottle beam resembles a dark hollow beam with an outside ring for symmetric cases, whereas it becomes divided into two or more separate lobes for the asymmetric cases. During propagation, both symmetric and asymmetric beams concentrate the intensity toward the center, eventually assuming a Gaussian shape, where this process seems to be more rapid for the former beam types. The rising trend of the kurtosis parameter of bottle beams changes to a falling trend when the refractive index structure constant is reduced from 10(-14) to 10(-13) m(-2/3). (C) 2019 Society of Photo-Optical Instrumentation Engineers (SPIE)
Citation - WoS: 8
Citation - Scopus: 8
Radius of Curvature of Bessel and Modified Bessel Gaussian Beams
(Elsevier Science Bv, 2013) Eyyuboglu, Halil Tanyer; Ji, Xiaoling; 7688; 06.02. Elektronik ve Haberleşme Mühendisliği; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
We analyze the radius of curvature of Bessel Gaussian (BG) and modified Bessel Gaussian (mBG) beams. The study is based on the results of analytic derivation as well as those of the random phase screen approach. Our results are displayed in graphs as variations of radius of curvature against propagation distance at various settings of beam order, width parameter, source focal length, wavelength, refractive index structure constant. Our findings indicate that mBG beams, in general will have larger radius of curvature values than BG beams. It is further observed that increases in beam order will lead to greater radius of curvatures. Rises in the width parameter will reveal more the differentiations between BG and mBG beams. At small focal lengths, the difference between BG and mBG beams is hardly noticeable. Higher wavelengths will initially cause a reduction in the radius of curvature, but at longer propagation distances, the reverse will happen. Increases in the refractive index structure constant will lead to smaller radius of curvature values. A general agreement is found in comparing the analytic results of BG beams with those of phase screen approach. (C) 2013 Elsevier B.V. All rights reserved.
Citation - WoS: 77
Citation - Scopus: 73
Simulator for General-Type Beam Propagation in Turbulent Atmosphere
(Optical Soc Amer, 2006) Arpali, Caglar; Yazicioglu, Canan; Eyyuboglu, Halil Tanyer; Arpali, Serap Altay; Baykal, Yahya; 7688; 7812; 51304; 06.08. Mekatronik Mühendisliği; 06.02. Elektronik ve Haberleşme Mühendisliği; 06.03. Elektrik-Elektronik Mühendisliği; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
A simulator is designed in MATLAB code which gives the propagation characteristics of a general-type beam in turbulent atmosphere. When the required source and medium parameters are entered, the simulator yields the average intensity profile along the propagation axis in a video format. In our simulator, the user can choose the option of a "user defined beam" in which the source and medium parameters are selected as requested by the user by entering numerical values in the relevant menu boxes. Alternatively, the user can proceed with the option of "pre-defined beam" in which the average intensity profiles of beams such as annular, cos-Gaussian, sine-Gaussian, cosh-Gaussian, sinh-Gaussian, their higher-order counterparts and flat-topped can be observed as they propagate in a turbulent atmosphere. Some samples of the simulator output are presented. (c) 2006 Optical Society of America