Abdurrahim Toktas

Ankara University · Department of Artificial Intelligence and Data Engineering

Temporal Convolutional Network (TCN) has received extensive attention in the field of speech synthesis. Many researchers use TCN-based models for action segmentation since both tasks focus on contextual connections. However, TCN can only capture the long-term dependencies of information and ignores the short-term dependencies, which can lead to ove...

A chaotic system is a mathematical model exhibiting random and unpredictable behavior. However, existing chaotic systems suffer from suboptimal parameters regarding chaotic indicators. In this study, a novel leader Pareto grey wolf optimizer (LP-GWO) is proposed for multiobjective (MO) design of 2D parametric hyperchaotic system (2D-PHS). The MO ca...

In this paper, a cyclic memristive neural network structure is proposed. There are counterclockwise connections between the neurons. The system generates a controllable number of multi-scroll chaos by means of memristors with multi-segment nonlinear functions, which can produce a controllable infinite coexistence of heterogeneous attractors with in...

Image encryption (IE) has been essential for internet-based storing and transferring in recent years. Effective chaotic systems play a crucial role in IE schemes which widely depend on chaotic maps and keys. However, the existing chaotic maps suffer from low performance and narrow chaotic ranges, and they utilize casual key generation approaches ra...

A chaotic map plays a critical role in image encryption (IME). The map used to generate chaotic sequences should perform high dynamic characteristics. In this study, a new chaotic system depending on the Bessel function, so-called Bessel map, and a novel Bessel map-based IME scheme are proposed for the IME. The Bessel map has three control paramete...

Image retrieval (IR) methods extract the most relevant images to the query images from an image database. The existing IR methods, which retrieve images with a low degree of similarity, use computationally expensive approaches. In this study, a novel Multi-Label Multi-Query IR (MLMQ-IR) method based on the variance of Hamming distance is presented...

Currently, discrete memristors are a focal point in the study of chaotic mappings. Similar to memristors, memcapacitors—another type of memory circuit component—have not received widespread attention in the design of chaotic mappings. In this paper, we propose a four-dimensional memcapacitive hyperchaotic Logistic map (4D-MHLM) by integrating memca...

A novel multi-space confusion image encryption (MSC-IE) method based on 2D Vincent map is presented in this study. In order to provide a more secure method, the MSC-IE consists of two-stage column and row permutation processing. The 2D Vincent map is derived from the Vincent function, which is an optimization benchmark function. The chaotic perform...

This paper devises an effective image encryption algorithm that exploits a novel hyperchaotic map and is applicable to a variety of image encryption scenarios. The newly designed hyperchaotic map exhibits enhanced ergodicity, more intricate behavior, and a substantial chaotic range, as revealed by performance evaluation. The encryption algorithm un...

A novel 2D chaotic system is presented, which is inspired by Styblinski Tang (ST) function employed as optimization test function. It is a challenge function because of having many local optima. The performance of the chaotic system namely 2D Styblinski Tang (2D-ST) map is corroborated through an extensive comparison with the literature in terms of...

This paper proposes an index-based simultaneous permutation-diffusion image encryption algorithm (ISPD-IEA) based on chaos theory and a permutation-diffusion coupled encryption mechanism. The proposed method introduces a novel two-dimensional (2D) Price map derived from the Price function and classical maps, exhibiting superior chaotic dynamical pr...

Chaotic map is a kind of discrete chaotic system. The existing chaotic maps suffer from optimal parameters in terms of chaos measurements. In this study, a novel approach of optimization of parametric chaotic map (PCM) using triple objective optimization is presented for the first time. A PCM with six parameters is first conceived and then optimize...

The hyperchaotic systems are essentially needed for various applications, especially multimedia encryption, watermarking and communications. However, existing chaotic systems have limited chaotic performance in terms of precise chaos measuring tools like bifurcation and attractor diagrams, Lyapunov exponent (LE), 0-1 test, correlation dimension (CD...

An ultra-wideband millimeter-wave (mmWave) monopole antenna is presented. The antenna with a size of 10 × 10 × 0.508 mm3 operates between 20.8 and 46.4 GHz. It consists of a half-elliptic monopole patch with two slots and a defected ground plane with a triangularly cornered notch. The monopole is fed by a stepped impedance-matched transmission line...

To provide robust security measures for audio data during transmission, this paper has developed a novel dual-channel audio encryption scheme based on chaos theory. Specifically, a new 2D chaotic system called two-dimensional Infinite Collapse with Logistic Map (2D-ICLM) is designed in this paper. Compared to traditional 2D chaotic systems, the 2D-...

This paper designs a new medical image encryption scheme based on a new hyperchaotic map, which exhibits excellent security and high efficiency that can be applied to medical images of distinctive presentation formats. Firstly a two-dimensional Logistic-Gaussian hyperchaotic map (2D-LGHM) with a wide range of hyperchaos is constructed, and performa...

Chaotic systems are the most essential tools for wide range of applications such as communication, watermark-ing, data compression and multimedia encryption. However, the existing chaotic systems suffer from low complexity and randomness. In this study, a novel 2D hyperchaotic system denoted as Schaffer map is conceived for high complexity required...

Images serve as a valuable information carrier for their properties of visualization and holding a large amount of messages. This paper presents a novel chaos-based encryption scheme to protect images from being captured or attacked. Firstly a two-dimensional Salomon map inspired by the Salomon function is proposed and there is a comprehensive comp...

This research presents a study on the nano-carbon black (NCB) added ultra-weight foam concrete by revealing its potential utilization of multi-layer microwave absorbing foam concrete (MMAFC). The fresh and hardened properties of the foam concrete samples were investigated. Four concrete samples were constituted by adding NCB with 0%, 5%, 10% and 15...

Background Circularly polarized (CP) antenna is an effective choice for wireless systems due to its insensitivity to the orientations of electromagnetic waves. Objective A novel CP triangular patch antenna (CPTA) system is designed for ultra-wideband (UWB) applications. Methods The CPTA, with a total size of 40.6 x 40.9 x 1.6 mm3, comprises a tri...

In this study, a novel 2D fully chaotic map (FULLMAP) derived through a multi-objective optimization strategy with artificial bee colony (ABC) algorithm is introduced for image encryption procedures (IMEPs). First, a model for FULLMAP with eighth decision variables was empirically constituted, and then, the variables were optimally determined using...

Artificial bee colony (ABC) and differential evolution (DE) are the most powerful and operative meta-heuristic algorithms inspired by the nature. Although both algorithms are successful, their successes vary from phase to phase, i.e. while ABC is better in the exploration ability, DE is well in the exploitation capability. Because the diversity of...

A secure and reliable image encryption scheme is presented, which depends on a novel chaotic log-map, deep convolution neural network (CNN) model, and bit reversion operation for the manipulation process. CNN is utilized to generate a public key to be based on the image in order to enhance the key sensitivity of the scheme. Initial values and contr...

Tailoring a deep convolutional neural network (CNN) for an implementation is a tedious and time-consuming task especially in image identification. In this study, an optimization scheme based on artificial bee colony (ABC) algorithm so-called optimal deep CNN (ODC) classifier for hyperparameter optimization of deep CNN is proposed for plant species...

A chaotic map generally employed to generate chaotic sequence is key element for an image encryption algorithm (IEA). In this study, an IEA using novel 2D chaotic map, which is based on Euler and Pi numbers so-called eπ-map, is presented. eπ-map exploits infinity diversity attribute of these numbers. Moreover, a diffusion operation referred to as “...

The resonant frequency values of 144 ECMAs were determined by the commercial electromagnetic simulator IE3D™ (IE3D™, version 14) running on MoM. MLP was used to model the relationship between the simulated antenna parameters, which are patch dimensions and dielectric constants, and corresponding resonant frequency values.

Abstract—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 Pimap...

Chaotic maps used to shuffle and manipulate the image pixels are important for image encryption (IE). In this study, a novel 2D optimized chaotic map (OPMAP) using a triple-objective differential evolution (TODE) algorithm is presented for IE. A model for OPMAP with eight decision variables is empirically designed, and then its variables are determ...

In this study, a method based on surrogate model (SM) for computational analysis of antenna parameters such as the resonant frequency (RF) and bandwidth (BW) is presented. Moreover, it is attempted to optimize the SM using evolutionary optimization algorithms in order to further improve the accuracy of the SM. In the conventional computational appr...

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, permutat...

A novel optimal chaotic map (OCM) is proposed for image encryption scheme (IES). The OCM is constructed using a multi-objective optimization strategy through artificial bee colony (ABC) algorithm. An empirical model for the OCM with four unknown variables is first constituted, and then, these variables are optimally found out using ABC for minimizi...

A secure and reliable image encryption scheme is presented in this study. The encryption scheme hereby introduces a novel chaotic log-map, deep convolution neural network (CNN) model for key generation, and bit reversion operation for the manipulation process. Thanks to the sensitive key generation by the CNN, initial values and control parameters...

Artificial bee colony algorithm (ABC) developed by inspiring the foraging phenomena of the natural honey bees is a simple and pow-erful metaheuristic optimization algorithm. The performance of sin-gle objective ABC performance has been well demonstrated by im-plemented to different design optimization problems from electrical and mechanical to civi...

This chapter provides an introduction and overview of this book content titled Nature-Inspired Metaheuristic Algorithms for Engineering Optimization Applications. This book supplies both theoretical standpoints and practical examples for engineering researchers and/or practitioners taking roles in obtaining optimum designs of engineering applicatio...

Flower pollination algorithm (FPA) is an outstanding metaheuristic optimization approach among the recently emerged nature inspired algorithms. It is built on pollination nature of the flowers, classify-ing into two categories; biotic and abiotic pollinations. It is observed that the performance of FPA has been well demonstrated through diverse eng...

Artificial bee colony algorithm (ABC) developed by inspiring the foraging phenomena of the natural honey bees is a simple and powerful metaheuristic optimization algorithm. The performance of single objective ABC performance has been well demonstrated by implemented to different design optimization problems from elec-trical and mechanical to civil...

Although various optimization methods for solving single-objective problems have been developed since last decades, these methods have lost their eligibility due to the fact that today's engineering problems toward multiple-objective optimization problems, in real applications. For single-objective optimization problems, e.g. in case of a minimizat...

Although various optimization methods for solving single-objective problems have been developed in the last few decades, these methods have lost their eligibility due to the fact that today’s engineering problems are toward multiple objective optimization problems, in real applications. For single-objective optimization problems, for example, in ca...

The construction sector constitutes a significant portion of global gross national expenditures with huge financial budget requirements and provides employment for more than one hundred million peo-ple. Besides, considering that people spend more than 80% of their time indoors today, it is necessary to make optimal structure de-signs. This requirem...

The construction sector constitutes a significant portion of global gross national expenditures with huge financial budget requirements and provides employment for more than one hundred million people. Besides, considering that people spend more than 80% of their time indoors today, it is necessary to make optimal structure designs. This requiremen...

This book engages in an ongoing topic, such as the implementation of nature-inspired metaheuristic algorithms, with a main concentration on optimization problems in different fields of engineering optimization applications. The chapters of the book provide concise overviews of various nature-inspired metaheuristic algorithms, defining their profits...

Published version: https://link.springer.com/article/10.1007/s11042-021-11803-1

An adaptive flower pollination algorithm (AFPA) is evolved with respect to the accuracy and stability performance. AFPA is developed by modifying both global and local search operators. The exploration and exploitation abilities of the algorithm are thus improved by integrating a spatial dispersal mechanism adapting with the number of iterations to...

In this study, a dual-element inverted multiple input multiple output (MIMO) F antenna (IFA) operating at 2.4 GHz band is designed by means of computational electromagnetic for WLAN wireless devices. The shape of IFA element resembles two superimposed E-shaped strips. IFA element with a small size of 10 x 13 mm2 operates at the frequency range of 2...

A Multilayer Radar Absorbing Material (MRAM) based on composite is designed using a dual-objective optimization method butterfly optimization algorithm (BOA). The two objective functions regard Total Reflection (TR) involving sub-reflection at the inner layers and Total Thickness (TT). In order to make the MRA material more applicable for real appl...

A three-dimensional objective space (3DOS) optimization strategy using an enhanced multi-objective artificial bee colony (ABC) algorithm for the design optimization of layered radar absorbing material (LRAM) is presented in this study. The multi-objective exploitation ability of ABC is improved with regard to the convergence and diversity by integr...

A triple-objective scheme with a novel enhanced artificial bee colony (ABC) algorithm is presented for fully optimized design of multi-layer radar absorbing material (MRAM). The exploitation ability of ABC is further enhanced by integrating with butterfly optimization algorithm (BOA), denoted butterfly-integrated ABC (BiABC). The performance of BiA...

Purpose In line with computational technological advances, obtaining optimal solutions for engineering problems has become attractive research topics in various disciplines and real engineering systems having multiple objectives. Therefore, it is aimed to ensure that the multiple objectives are simultaneously optimized by considering them among the...

Multilayer radar absorbing material (MRAM) is composed by superimposing different dielectric material layers with various thicknesses for reducing the reflection of electromagnetic (EM) wave. In this study, a novel triple-objective optimisation scheme based on Pareto-integrated artificial bee colony (P-ABC) algorithm is presented for the fully-opti...

Inverse synthetic aperture radar (ISAR) image is constructed using 2-D spatial distributions of the radar cross section of a target. ISAR data gathered from moving targets might include interphase error that causes a blurry effect in the ISAR image. In this article, an efficient motion compensation (MC) scheme depending on multicriteria decision us...

Günümüz haberleşme teknolojisinde kablosuz haberleşme sistemleri gün geçtikçe önem kazanmıştır. Bir kablosuz mobil sistem düşünüldüğünde, bu sistemin maliyet ve performansı öne çıkmaktadır. En önemli amaçlardan bir tanesi de anteninin boyutu küçüldükçe çalışma frekansını değiştirmeden verimli anten tasarımları yapabilmektir. Bu bağlamda, küçük fizi...

Mikroşerit antenler, kompakt yapıları ve baskı devre teknolojisi ile entegre ve kolay üretimi gibi avantajlarından dolayı son yıllarda haberleşme, savunma ve biyomedikal alanında yoğun bir şekilde kullanılmaktadır. Bu nedenle, bu uygulamalara yönelik küçük ve geniş bant anten tasarımı önem kazanmıştır. Bu çalışmada, 6.19 – 13.71 GHz rezonans frekan...

Today, advances in defense and communication have increased the need for compact and ultra-wideband antennas. For this reason, microstrip antennas have attracted intense interest in recent years as they are simple and smooth, small in size and easily applied to integrated circuits. In this study, a new compact ultra-wideband microstrip antenna is d...

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 mm2 ground plane. To alleviate the mutual coupl...

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. Sol...

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 communicatio...

Buluş, taşınabilir kablosuz el cihazlarına uyumlu, LPDA (log-periodic dipole array) prensibine dayanan özgün geniş-bant bir MIMO (multiple input multiple output - çok girişli çok çıkışlı) anten sistemidir.

Meteorological events have become an indispensable part of our daily life. The estimation/analysis of the meteorological data helps us to put our daily work on the track. Thanks to weather forecasts made by meteorological stations, we take precautions in many areas of our lives and prevent weather events from adversely affecting our lives. In this...

Design of multi-layer radar absorber material (MRAM) is a multi-objective problem for minimizing total reflection (TR) together with the total thickness (TT) by selecting optimum variables such as the material type for each layer from a material database and determining the thickness of each layer. In this paper, five-layer broadband and wide-incid...

Millimeter-wave synthetic aperture radar (SAR) implementations need many sampling points that means huge data collection and long processing time. Owing to compressed sensing, SAR data can be easily reconstructed with fewer random samples than Shannon/Nyquist criteria. The most used sampling strategy is to select samples from all spatial-frequency...

This article deals with the analysis of T‐shaped patch antennas (TPAs) that operates between 1 and 7 GHz at triple‐band characteristics. A TPA is composed of three monopole structures so that it has triple‐resonant frequency. Neurocomputational (NC) models eliminate the complex procedures for the analysis of patch antennas with irregular shapes. In...

In this study, a real-time system which counts the number of people with the help of a camera was demonstrated. The system can send the number of people to a mobile application via Internet of Things (IoT) and monitor simultaneously. This work is carried out in the main library of Inonu University. Background subtraction method was used to recogniz...

In this paper, artificial intelligence techniques (AIT) such as artificial neural network, naive bayes algorithm, random forest algorithm, K-nearest neighborhood (KNN) and support vector machine (SVM) are implemented to design an automatic identifier for the plant leaves. For this purpose, data of 637 healthy leaves consisting of 32 different plant...

A compact UWB G‐shaped printed monopole antenna with reconfigurable band‐notched characteristic is presented. The antenna design having a low profile of 8 × 27.5 mm2 consists of a G‐shaped radiating element size of 8 × 8 mm2 fed by a microstrip transmission line with a matching line and a defected ground structure. In order to achieve reconfigurabl...

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, v...

In this study, an image processing techniques (IPTs) and a Sugeno-typed neuro-fuzzy system (NFS) model is presented for classifying the wheat grains into bread and durum. Images of 200 wheat grains are taken by a high resolution camera in order to generate the data set for training and testing processes of the NFS model. The features of 5 dimension...

In this study, a quad-port multi-polarized ultra-wideband (UWB) multiple input multiple output (MIMO) antenna system with a new isolation technique is designed for wireless devices. The antenna structure consists of four triangular monopole elements and neutralization ring (NR) structures. The monopoles are back-to-back positioned in symmetrical an...

In this study, applications of well-known neural networks such as arti- �cial neural network (ANN), adaptive neuro-fuzzy inference system (ANFIS) and support vector machine (SVM) for wheat grain classi�cation into three species are comparatively presented. The species of wheat grains which are Kama (]70), Rosa (]70) and Canadian (]70) are designate...

L-shaped patch antenna (LPA) is formed by combining two monopole patch radiators. Proper modelling of a LPA using lumped elements is crucial in antenna design and analysis. In this study, a novel equivalent circuit (EC) modeling of an LPA using differential evolution (DE) algorithm is presented. Two parallel branches each represents the monopole pa...

In this paper, a color feature-based classification of the wheat grains into bread and durum using artificial neural network (ANN) model with bayesian regularization (BR) learning algorithm is presented. Images of 200 wheat grains are taken by a high resolution camera in order to generate the data set for training and testing processes of the ANN-B...

In this study, classification of two types of wheat grains into bread and durum was carried out. The species of wheat grains in this dataset are bread and durum and these species have equal samples in the dataset as 100 instances. Seven features, including width, height, area, perimeter, roundness, width and perimeter/area were extracted from each...

In this study, a compact ultra-wideband (UWB) multiple input multiple output (MIMO) antenna system is designed for mobile terminals. The antenna system consists of two symmetrical 8x8 mm2 square antenna elements fed by a 50 Ohm microstrip transmission line (MTL). The UWB MIMO antenna operates at large frequency range of 2.5–13.3 GHz with an isolati...

In this paper, an image processing technique (IPT) based artificial neural network (ANN) model using bayesian regularization (BR) learning algorithm is presented for classifying the wheat grains into bread and durum. Images of 200 wheat grains are taken by a high resolution camera in order to generate the data set for training and testing processes...

The millimetre wave (MW) applications has become very popular in recent years due to the high-resolution requirement in inverse synthetic aperture radar (ISAR) imaging. The most important problem encountered in MW imaging method is the high data collection requirement. Compressed sensing (CS) is often used in MW applications because it allows proce...

The notch antenna is constructed by slotting one side of rectangular patch placed on a substrate over the ground plane. The analysis of notch antenna is complicated and very difficult due to non-uniform shape. In this work, a novel resonant length expression in calculating is proposed for the notch antenna. The expression regarding the resonant len...

Determination of the operating frequency of notch antennas by simulation or measurement is both more complicated, difficult and long time consuming. In this study, Artificial Neural Network (ANN) and Extreme Learning Machines (ELM) are used for operating frequency determining and then the performances of both algorithms are compared. In order to ob...

Ground based synthetic aperture radar (GB-SAR) is a powerful imaging system which generates high resolution images of ground objects. The most challenging problem of this topic is, the removing of ground and multipath reflections from the reconstructed image. In this study Constant False Alarm Rate (CFAR) detector is used to remove clutters from GB...

In this study, an image processing techniques (IPTs) and a Sugeno-typed neuro fuzzy system (NFS) model is presented for classifying the wheat grains into bread and durum. Images of 200 wheat grains are taken by a high resolution camera in order to generate the data set for training and testing processes of the NFS model. The features of 5 dimension...

BACKGROUND A computer vision-based classifier using adaptive neuro-fuzzy inference system (ANFIS) is designed for classifying wheat grains into bread or durum. To train and test the classifier, images of 200 wheat grains (100 for bread and 100 for durum) are taken by a high resolution camera. Visual feature data of the grains related to dimension (...

In this paper, acolor feature-based classification of the wheat grains into bread and durum usingartificial neural network (ANN)model with bayesian regularization (BR) learning algorithm is presented. Images of 200 wheat grains are taken by a high resolution camera in order to generate the data set for training and testing processes of the ANN-BR m...

Reconstructed ground based synthetic aperture radar (GB-SAR) data generally presents high resolution images of objects on the ground. However ground and multipath reflections occurred from depression angle appear as a clutter signs in the image. Constant false alarm rate (CFAR) detector is commonly preferred threshold algorithm for removing the clu...

BACKGROUND A simplified computer vision-based application using artificial neural network (ANN) depending on multilayer perceptron (MLP) for accurately classifying the wheat grains into bread or durum is presented. The images of 100 bread wheat grains and 100 durum wheat grains are taken via a high resolution camera and they are subjected to a pre...

Low-profile band-notched G-shaped ultra-wideband (UWB) multiple input multiple output (MIMO) antenna design for mobile terminals has been presented in this paper. In this context, two UWB MIMO antenna systems have been designed: The first is with square elements and the second is with G- shaped elements. A MIMO antenna with two symmetrical square...

An artificial neural network (ANN) based estimator is presented for notch antenna analysis in terms of the operating frequency. The notch antenna is formed by loading an asymmetric slot on one side of a rectangular patch. Architecture of the estimator is constructed over an ANN model trained with the simulated data of the notch antennas. In order t...

The notch antenna is constructed by slotting one side of rectangular patch placed on a substrate over the ground plane. The analysis of notch antenna is crucial owing to irregular shape. In this study, a novel resonant length expression in calculating the operating frequency is proposed for analyzing notch antennas. The expression regarding the res...

An ultra-wideband (UWB) monopole microstrip antenna is designed in this study. The design consists of a radiating triangular patch antenna (TPA) fed through a 50 Ohm microstrip transmission line (MTL) constructed over a defected ground structure (DGS). The triangular monopole well is matched to MTL with inserting a thin strip line. The performance...