Bilgisayar Mühendisliği Bölümü, Bildiri & Sunum Koleksiyonu

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https://hdl.handle.net/11492/3541

Listeleniyor 1 - 20 / 21

A new Pi-based chaotic map for ımage encryption
(Institute of Electrical and Electronics Engineers Inc., 2021) Erkan, Uǧur; Toktaş, Abdurrahim; Toktas, Feyza
Novel chaotic map (CM) based on pi number socalled Pi-map is introduced for image encryption scheme (ImES). The chaotic behavior of the Pi-map is appreciated with respect to Lyapunov Exponent (LE) and bifurcation graphs. The LE which is stable and highest is also compared those reported elsewhere. The image encryption performance of Pi-map is corroborated on a simple ImES consisting of only two operations which are permutation and diffusion. The ImES with Pi-map is crypto-studied through various analysis and, they are even crosschecked with the others in the literature. It is shown that ImES is eminent and reliable thanks to the capability of the Pi-map regarding randomness and complexness.
Design and kinematic analysis of a 6-DOF asymmetric parallel robot manipulator with 4-SPS and 2-CPS Type legs
(Institute of Electrical and Electronics Engineers Inc., 2021) Toz, Metin
This paper presents the design, inverse kinematic, Jacobian and workspace analysis of a six Degrees of Freedom (6-DOF) asymmetric parallel robot manipulator. The manipulator was designed by two CPS and four SPS type legs (C: passive cylindrical joint, P: active prismatic joint, S: passive spherical joint). The mechanism includes two passive cylindrical joints at the lower ends of its two legs instead of the spherical joints as in its symmetrical counterparts. Thus, the asymmetry of the mechanism is because of the two cylindrical joints. The basic mathematical formulations for inverse kinematic and Jacobian matrix analyses are given, and the effects of the cylindrical joints on the reachable workspace of the mechanism are presented. Moreover, the dextrous translational workspace of the mechanism is also obtained and compared by the workspace of the classic symmetrical six DOF SPS parallel manipulator. The results show that using cylindrical joints make the mechanism has better workspace characteristics than the classical one.
A novel euler chaotic map for image encryption
(Institute of Electrical and Electronics Engineers Inc., 2021) Erkan, Uğur; Toktaş, Abdurrahim; Toktaş, Feyza
A novel chaotic map based on Euler number namely Euler Map (EMAP) is suggested for image encryption algorithms (IEAs). The chaotic behavior of EMAP is appreciated with bifurcation analysis and Lyapunov Exponent (LE). The LE is the best due to the ultimate and most stable characteristic in case compared with the literature. A two-stage IEA, permutation and diffusion, is used to demonstrate the successful performance of EMAP, and this is how the success of EMAP is verified. The IEA with EMAP is examined in secure cryptanalyses and computational complexity. Some results are validated with the state of the arts. In the comparison, the suggested EMAP-based IEA stands out due to the diversity and complexity performance. It achieves a cropped image having minimum loss, a good operation time of 0.2297s and a low computational complexity. Therefore, the proposed EMAP can be applied to realistic systems.
Single image dehazing with optimal color channels and nonlinear transformation
(Institute of Electrical and Electronics Engineers, 2021) Le Thi Thanh; Thanh, Dang N. H.; Nguyen Ngoc Hien; Erkan, Uğur; Prasath, V. B. Surya
Image dehazing is an important problem and it is useful as a preprocessing step in various automatic image analysis systems. The goal of image dehazing is the quality improvement of digital images by removing haze across the scene. In the present work, we consider an automatic image dehazing approach that is based on optimal color channels and nonlinear transformations. The proposed dehazing approach can remove haze fast and effectively with features preservation. In our experiments, we compare the image dehazing results with related image dehazing methods from the literature. Visual assessments, as well as quantitative assessments, are also done to show the improvements obtained by the dehazing model across different natural images. Obtained experimental results indicate that the dehazing approach proposed hem performs better than other dehazing models in terms of overall better visual quality and higher blind image quality metric values.
Adaptive thresholding skin lesion segmentation with gabor filters and principal component analysis
(Springer, 2020) Thanh, D.N.H.; Hien, N.N.; Surya, Prasath, V.B.; Erkan, Uğur; Khamparia, A.
In this article, we study and propose an adaptive thresholding segmentation method for dermoscopic images with Gabor filters and Principal Component Analysis. The Gabor filters is used for extracting statistical features of image and the Principal Component Analysis is applied for transforming features to various bases. In experiments, we implement tests with the ISIC dataset. Segmentation results are assessed by the Dice and the Jaccard similarities. We also compare the proposed method to other similar methods to prove its own effectiveness. © Springer Nature Singapore Pte Ltd. 2020.
Design of quad-port circular MIMO antenna with isolation improved by shorting walls
(IEEE, 2019) Toktaş, Abdurrahim; Üstün, Deniz; Tekbaş, Mustafa
A compact co-located quad-port circular multiple-input-multiple-output (MIMO) antenna system operating at a wide frequency range of 3.0 - 5.0 GHz is designed in this study. The antenna system comprises a 20 mm radius circular patch composed of four co-located elements fed by 50 Ohm probe and a 50 x 50 mm(2) ground plane. To alleviate the mutual coupling among the antenna elements, the circular patch is split into four quadrants using two orthogonal shorting walls (SWs). In order to further improve the impedance matching, two circular slots are etched on the edge of the elements. The mutual coupling reducing performance of the SW is examined through the surface current and E-field distributions. The performance analysis of the MIMO system, regarding the radiation patterns, envelope-correlation-coefficient (ECC) and peak gain is thoroughly investigated. The antenna system is eligible for especially the access points due to being compact and versatile.
An image inpainting method based on adaptive fuzzy switching median
(IEEE, 2020) Nguyen Van Son; Dang N H Thanh; Erkan, Uğur
Image inpainting is an important problem of image processing that has many applications. The goal of the image inpainting problem is to restore or fill the corrupted or missing regions of image. In this paper, we propose an image inpainting method based on the adaptive fuzzy switching median. The adaptive fuzzy switching median is to provide an accurate estimation for the values of corrupted pixels when there are many corrupted pixels on image. In the experiments, we implement the proposed method on an open dataset of real natural images. We utilize standard image quality assessment metrics such as the peak signal-to-noise ratio metric and the structured similarity metric to compare the inpainting result of the proposed method with other similar inpainting methods to prove its effectiveness. The proposed inpainting method is also extended to process colorful images.
Application of wireless sensor networks in precision apiculture
(Latvia Univ Agriculture, Faculty Engineering, Inst Mechanics, 2015) Kviesis, Armands; Zacepins, Aleksejs; Durgun, Mahmut; Tekin, Saban; Malinovska, L; Osadcuks, V
Wireless sensor networks are used in different fields. One of the fields, where such sensors can be used is apiculture for honey bee (Apis Mellifera L.) monitoring (for example, temperature and humidity data acquisition). This paper introduces a wireless sensor network system for bee colonies online monitoring. The developed wireless system consists of several wireless measurement nodes which transfer colony data to one main unit, which then sends the received data to the cloud database server. Users can see and analyze data using the developed Web system. To this moment temperature and humidity are monitored using the SHT15 sensor. Real time temperature and humidity monitoring of the bee colonies can provide the beekeeper with actual and timely data and information to help identify various states of the bee colonies. Due to the fact, that these sensor data are transmitted wirelessly, it is also easier for the beekeeper to set up such a system (there is no wiring needed).
A model of deep neural network for iris classification with different activation functions
(IEEE, 2018) Eldem, Ayşe; Eldem, Hüseyin; Üstün, Deniz
In recent years, deep neural network (DNN) has been frequently used for classification. In this study, iris flowers having 3 different types are classified by using DNN which are utilized the width and length of petal and sepal features as input. Some experiments are made for the iris dataset by using different activation functions and different epoch numbers. Then, the activation function which gives the best result is determined. The classification success of the developed model is achieved 96% for the iris dataset.
Gpr image focusing using matched filter algorithm
(IEEE, 2018) Üstün, Deniz; Yiğit, Enes; Toktaş, Abdurrahim; Sabancı, Kadir; Duysak, Hüseyin
In this study a synthetic aperture radar-based reconstruction technique is applied to focus the unwanted disruptive effects in the two-dimensional ground penetrating radar data. The formulation of the applied Matched Filter Algorithm (MFA) which completely removes the hyperbolic effects is presented in detail. To test the capability of the proposed technique an experimental measurement setup is constructed in the laboratory and MFA is operated to gathered real GPR data. Thanks to the applied technique, high-resolution focused B-Scan GPR images are successfully obtained.
Wifi based indoor localization: application and comparison of machine learning algorithms
(IEEE, 2018) Sabancı, Kadir; Yiğit, Enes; Üstün, Deniz; Toktaş, Abdurrahim; Aslan, Muhammet Fatih
Because of increasing the use of smartphones, it has become easier to identify location of any user. The most popular technique for outdoor positioning is the GPS signal which is commonly used in smartphones and transport vehicles. However, position detection can not be achieved indoor with GPS. Therefore, in this study, a location determination based on WiFi signal strengths was performed indoor where user could not correctly receive the GPS signal. The data includes the strengths of seven WiFi signals that provide information about four different rooms. Based on the WiFi signal strength values coming from seven different sources to smartphone, the position of the user at which room can be determined. In this study, classification was achieved for the determination of the indoor room. Six different Machine Learning (ML) methods were applied to the classification. These methods are Artificial Neural Networks (ANN), K-Nearest Neighbors (k-NN), Decision Trees (DT), Naive Bayes (NB) Classifier, Extreme Learning Machine (ELM) and Support Vector Machines (SVM). Successful results were obtained from all the methods and these results were compared with each other.
Optimally synthesizing multilayer radar absorbing material (RAM) using artificial bee colony algorithm
(IEEE, 2018) Toktaş, Abdurrahim; Üstün, Deniz; Yiğit, Enes; Sabancı, Kadir; Tekbaş, Mustafa
Radar absorbing material (RAM) is crucial for military vehicles that desired to be invisible to the radar systems. A vehicle coated with optimally designed multilayer RAM (MRAM) can be successfully hidden from the radar systems. At this point, optimum design of a MRAM in terms of electrical and geometric variables gains importance. In this study, variables in design of MRAM with various numbers of layers are optimally determined using artificial bee colony (ABC) which is the one of latest natural inspired algorithm. The MRAMs are considered to operate at the frequency range of 2-8 GHz and 1-20 GHz at normal incident. In optimization, a predefined material set including electrical variables existing in the literature is utilized for making a fairly comparison. The electrical variables and thickness of each layer are optimized for the objective of minimizing the reflectivity for a limited total thickness. The optimization is conducted through the formulation of impedance equivalent model in order to form the objective function. The formulation is verified through the designed MRAMs via a full wave electromagnetic solver. Moreover, a comparison is studied through the simulated MRAMs proposed in this study and the suggested ones designed using different algorithms. The proposed designs have the lest total thickness than the other ones as well as almost the same reflectivity with the best one in the literature.
Grain moisture detection by using a-scan radar measurement
(IEEE, 2018) Yiğit, Enes; Sabancı, Kadir; Toktaş, Abdurrahim; Üstün, Deniz; Duysak, Hüseyin
The amount of moisture in stored grain is an important factor which affects food safety and grain quality. A sensible and accurate detection of the moisture content in stored grain is of great significance. In order to detect the grain moisture content non-destructively, the ability of the electromagnetic (EM) wave propagating through the grain can be exploited. While the conventional methods such as capacitive, gravimetric methods are suitable for measuring of moisture of small samples, the EM-based method is more suitable to measure grain moisture of larger samples. In this paper, the wheat moisture ratio is determined by means of A-Scan radar measurement. The radar backscattering signal belongs to air and wheat filled bin are obtained using vector network analyser(VNA) between 1 to 6 GHz for a total of 75 discrete points. The range gating process covering the same interval is performed to both (air and grain measurements) range profiles obtained by taking inverse Fourier transform (IFT) of the A-scan data. Then, the dielectric constant of the wheat is determined using phase information of A-scan data and the grain moisture content is calculated using the dielectric constants of grain, dried grain and water. The wheat moisture ratio is found with 0.6% error compared to actual ratio.
An UWB antenna design having band-reject characteristic by y-hhaped strip
(IEEE, 2018) Üstün, Deniz; Toktaş, Abdurrahim; Sabancı, Kadir; Yiğit, Enes; Toktaş, Feyza
In this study, an ultra-wide band (UWB) antenna having band-notched operation for WLAN application has been designed. To model the antenna design, HyperLynx (R) 3D electromagnetic simulation program is used. The UWB antenna operates between the frequencies of 2.5 GHz and 11 GHz. To obtain the ideal rejecting characteristic over the desired frequency band, a Y-shaped strip is added into the full UWB antenna radiator. Thus, a frequency rejection response is obtained in band range of 5.0 GHz and 6.0 GHz for WLAN application. By changing the size of the Y-shaped strip, not only center frequency for interval 5 GHz and 6 GHz but also rejected bandwidth can be readily shifted. As a result, A suitable notch characteristic is achieved for desired band thanks to optimized strip geometry.
An iterative image inpainting method based on similarity of pixels values
(IEEE, 2019) Erkan, Uğur; Enginoğlu, Serdar; Thanh, Dang N. H.
Image inpainting is a process of completion of missing places by using other undamaged sections of the image or removal of unwanted objects of the image. In this study, we propose a novel image inpainting method. This method constitutes an essential place in image processing. This proposed method fills the corrupted area by using the similarity of the boundary pixels values around that corrupted regions in every iteration step. Afterwards, to evaluate image inpainting quality of the proposed method, we use Peak Signal-to-Noise Ratio (PSNR) and Structural Similarity (SSIM) metrics and present some visual results. The acquired results show that our proposed inpainting method gives an outstanding performance to fill the corrupted areas and to remove objects. We also discuss the need for further research.
3D level measurement design by using multi static X-band radar
(Institute of Electrical and Electronics Engineers Inc., 2018) Yiğit, Enes; Toktaş, Abdurrahim; Sabancı, Kadir; Üstün, Deniz; Isiker H.
The quantity of stacks in silos has commercial importance. For this reason many systems have been developed to detect the quantity of the stack in silos. Most of these systems are based on single point measurements. In this study multi static (MS) thru-air radar (TAR) based three dimensional (3D) perception system is designed. The system consist of 4 X-Band horn antennas (one transmitter, three receiver) to make 3D level measurement. A commercial grain silo is used to test the success of the developed system. Thanks to the designed MS-TAR, range information of the powerful scattering points of grain surfaces are recognized and the average height information of the surface is obtained. Then, according to the height of the surface and the density of the grain, the quantity of the stack is obtained with high accuracy.
Cloud-based adjustable and section led pattern controlled street light
(Institute of Electrical and Electronics Engineers Inc., 2019) Durgun, Mahmut; Gökrem, L.
In this study, both the amount of light and the pattern control are focused on the street lamp, which can be managed over the cloud, which reduces energy consumption costs and can be applied according to the location. The proposed lighting unit is designed to be controlled and monitored remotely. The proposed street lighting provides specific lighting according to the lighting area. The lighting amount, position and fault conditions of the lamp can be monitored. Different control strategies have been proposed for various lighting scenarios. It is foreseen that this proposed system will be an innovative solution to existing lighting problems due to its practicality and efficiency.
A formulaic model calculating the permittivity of testing materials placed on a circular patch antenna
(IEEE Computer Society, 2019) Tekbaş, Mustafa; Toktaş, Abdurrahim; Üstün, Deniz
In this study, a formulaic model optimized by artificial bee colony (ABC) algorithm is presented for calculation of the relative permittivity of testing materials which placed on a coaxial-fed circular patch antenna (CPA). The CPA with patch diameter of 34 mm and thickness of 1.6 mm is designed for operating at a resonant frequency of 2.37 GHz. Solid materials to be tested, having a thickness of 2 mm and the patch diameter size, are placed on the antenna patch. Therefore, the resonant frequency and the quality factor of the CPA with the material would change depending on the permittivity of the solid material. The resonant frequency and the quality factor of the CPA with various solid materials (the relative permittivity from 1 to 100) are obtained by simulations. An optimum model is fitted by the ABC through the simulation data for calculation of the permittivity of testing solid material. The model is also verified over the calculated permittivity for three testing materials. Therefore, the permittivity of a testing material can be accurately determined by the model without using numerical or analytical electromagnetic solutions.
Design of quad-port circular MIMO antenna with isolation improved by shorting walls
(IEEE Computer Society, 2019) Toktaş, Abdurrahim; Üstün, Deniz; Tekbaş, Mustafa
A compact co-located quad-port circular multiple-input-multiple-output (MIMO) antenna system operating at a wide frequency range of 3. 0 - 5.0 GHz is designed in this study. The antenna system comprises a 20 mm radius circular patch composed of four co-located elements fed by 50 Ohm probe and a 50 x 50mm2 ground plane. To alleviate the mutual coupling among the antenna elements, the circular patch is split into four quadrants using two orthogonal shorting walls (SWs). In order to further improve the impedance matching, two circular slots are etched on the edge of the elements. The mutual coupling reducing performance of the SW is examined through the surface current and E-field distributions. The performance analysis of the MIMO system, regarding the radiation patterns, envelope-correlation-coefficient (ECC) and peak gain is thoroughly investigated. The antenna system is eligible for especially the access points due to being compact and versatile.
Determination of feed point by surrogate model based on radial basis function for rectangular microstrip antennas
(Institute of Electrical and Electronics Engineers Inc., 2019) Üstün, Deniz; Tekbaş, Mustafa; Toktaş, Abdurrahim
Due to the latest developments in communication systems, the technology of many devices developed for wireless communication systems have also changed. Therefore, the designs of antenna with properties that are lightweight, cost-effective, small-sized and a wide operating frequency range are very important to use in the mobile wireless communication systems. However, the use of computer-Added antenna analysis techniques that can obtain accurate results in order to design antenna designs quickly and effectively has gained importance. In this study, a surrogate model has been proposed to determine the optimal feed point of rectangular microstrip antennas. Twenty-Three antennas with different dimensions and dielectric constant values presented in the literature were used for the creation of the surrogate model. The predicted feeding results by the SM are being compatible with the optimal feed points of the antennas determined in the simulation.

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