Electrical - Electronic Engineering / Elektrik - Elektronik Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/11
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Article Citation - WoS: 1Citation - Scopus: 1Controlling the Rotor Angle Stability of Single Machine Infinite Bus System in the Presence of Wiener and Alpha-Stable Levy Type Power Fluctuations(World Scientific Publishing, 2020) Yılmaz, Serpil; Savacı, Ferit AcarThe integration of renewable energy sources into the power systems and the growth of electricity consumption leads to a considerable increase in the power fluctuations. In the first part of this study, the control of the rotor angle stability of single machine infinite bus system in the presence of Wiener type power fluctuations has been achieved by minimizing the corresponding stochastic sensitivity function. In the second part, the power fluctuations have been modeled by alpha-stable Levy processes and since stochastic sensitivity function is not available for alpha-stable Levy processes, then the control of the rotor angle stability has been numerically achieved by minimizing the corresponding rotor angle dispersion for the first time in the literature. © World Scientific Publishing CompanyArticle Citation - WoS: 1Citation - Scopus: 2Blind Recognition of Alpha-Stable Random Carrier Signals by an Eavesdropper in Random Communication Systems(Institution of Engineering and Technology, 2019) Ahmed, Areeb; Savacı, Ferit AcarInvisibility of alpha-stable (alpha -stable) noise as carrier signals, in the presence of additive white Gaussian noise (AWGN) as channel noise, is a key factor to ensure covert transmission by employing random communication systems (RCSs). This study introduces a novel blind recognition method for an eavesdropper to detect the presence of real-valued symmetric and skewed alpha -stable random carrier signals in the presence of AWGN. The introduced method is based on the proposed random carrier signal recogniser (RCSR), which consists of fractional lower-order auto-covariance block, threshold control block and the random carrier signal recognition indicator. The proposed RCSR first detects the possible presence of alpha -stable random carrier signals and then recognises the impulsiveness and skewness parameters, exploited by the transmitter and the intended receiver, to extract covertly conveyed binary information. However, the determined covert range can be adopted to perform secure transmission by RCSs. The simulation results reflect the simplicity of the proposed method as it is capable of performing effectively in real time by utilising extremely less number of observed samples.Article Citation - WoS: 5Citation - Scopus: 5Inverse System Approach To Design Alpha-Stable Noise Driven Random Communication System(Institution of Engineering and Technology, 2020) Savacı, Ferit Acar; Ahmed, AreebIn the proposed random communication system (RCS), the alpha-stable (alpha-stable) noise as a random carrier drives the transmitter which is modelled by the linear dynamical system and the skewness parameter of the random carrier encodes the binary messages. By selecting the receiver as the inverse system of the transmitter, the output of the receiver is ensured to be alpha-stable noise whose skewness parameters are then estimated to decode the binary messages. The response of a linear system to an alpha-stable process is again alpha-stable process, however, the skewness parameters of the response differs from that of the input which can only be recovered at the output of the inverse system. Hence, estimation of skewness parameter by an eavesdropper, without using the inverse system, will not reveal the true binary messages while the intended receiver truly decodes the binary messages. The proposed inverse system based RCS provides efficient performance which is shown by comparing the bit error rate of the intended receiver and an eavesdropper where the enhancement in covertness is shown by evaluating the covertness values of the proposed RCS.Article Citation - WoS: 3Citation - Scopus: 4Stochastic bifurcation in generalized chua's circuit driven by skew-normal distributed noise(World Scientific Publishing Co. Pte Ltd, 2018) Yılmaz, Serpil; Çek, Mehmet Emre; Savacı, Ferit AcarIn this study, the stochastic phenomenological bifurcations (P-bifurcations) of generalized Chua's circuit (GCC) driven by skew-normal distributed noise have been investigated by numerically obtaining the stationary distributions of the stochastic responses. The noise intensity and/or skewness parameters of skew-normal distributed noise have been chosen as the bifurcation parameters to change the structure of the stochastic attractor. While the number of breakpoints in the piecewise-linear characteristics of the GCC are fixed, it has been observed that the number of scrolls have been changed by tuning the noise intensity and the skewness parameter of the skew-normal distributed noise.Article Citation - WoS: 9Citation - Scopus: 13Synchronisation of Alpha-Stable Levy Noisebased Random Communication System(Institution of Engineering and Technology, 2018) Ahmed, Areeb; Savacı, Ferit AcarIn this study, the pilot-assisted synchronisation method for a random communication system (RCS) has been proposed. The pilot symbol, which has alpha-stable distribution, has been used to establish synchronisation and to maintain covertness in the RCS. The introduced synchronisation block (SB) consists of fractional lower-order covariance-based correlators (FLOCCs), threshold detectors (TDs) and the synchronisation control block. To measure the performance of the proposed SB, the performance criterion, i.e. confidence ratio (CR), has been proposed. The reliability of the proposed SB can be enhanced by altering the CR and the achieved CR by using the FLOCCs and TDs in SB.Article Citation - WoS: 4Citation - Scopus: 4Bayesian Stable Mixture Model of State Densities of Generalized Chua's Circuit(World Scientific Publishing Co. Pte Ltd, 2015) Savacı, Ferit Acar; Yılmaz, SerpilIn this paper, the probability density functions (PDFs) of the states of Generalized Chua's Circuit (GCC) have been modeled by Finite Mixture α-Stable (FMαS) distributions which is a Bayesian mixture model of α-stable distributions and it provides semiparametric characterization for the distributions of multiscroll chaotic attractors. Fully Bayesian approach has been applied to estimate the mixture parameters of multimodal distributions corresponding to the multiscroll chaotic attractors.Article Citation - WoS: 14Citation - Scopus: 16Random Communication System Based on Skewed Alpha-Stable Levy Noise Shift Keying(World Scientific Publishing Co. Pte Ltd, 2017) Ahmed, Areeb; Savacı, Ferit AcarThe digital communication system is based on the skewed alpha-stable (α-stable) noise sequence which is chosen as the random carrier to modulate the binary message at the transmitter side. Antipodal characteristic of the skew parameter beta (β) is exploited for decoding information at the receiver side to obtain a secure communication system. A fast estimator used in this paper is based on Modified Extreme Value Method (MEVM) to extract the binary message from the signal received through the Additive White Gaussian Noise (AWGN) channel. Our proposed receiver is achieving better bit error rate (BER) versus Mixed Signal to Noise Ratio (MSNR) than previously introduced receivers which are based on Sinc and Logarithmic estimators. MEVM estimator is indeed less complex compared to the Sinc and Logarithmic estimators and hence more fast. Additionally, the criterion to measure the security level of random communication system, which is based on α-stable noise sequence, has also been introduced.Article Citation - WoS: 5Citation - Scopus: 5Steady-State Analysis of Nonlinearly Coupled Chua's Circuits With Periodic Input(World Scientific Publishing Co. Pte Ltd, 2003) Savacı, Ferit Acar; Yalçın, M. E.; Güzeliş, CüneytIn this paper, nonlinearly coupled identical Chua's circuits, when driven by sinusoidal signal have been analyzed in the time-domain by using the steady-state analysis techniques of piecewise-linear dynamic systems. With such techniques, it has become possible to obtain analytical expressions for the transfer functions in terms of the circuit parameters. The proposed system under consideration has also been studied by analog simulations of the overall system on a hardware realization using off-the-shelf components as well as by a time-domain analysis of the synchronization error.Article Skewed Alpha-Stable Distributions for Modeling and Classification of Musical Instruments(Türkiye Klinikleri Journal of Medical Sciences, 2012) Özbek, Mehmet Erdal; Çek, Mehmet Emre; Savacı, Ferit AcarMusic information retrieval and particularly musical instrument classification has become a very popular research area for the last few decades. Although in the literature many feature sets have been proposed to represent the musical instrument sounds, there is still need to find a superior feature set to achieve better classification performance. In this paper, we propose to use the parameters of skewed alpha-stable distribution of sub-band wavelet coefficients of musical sounds as features and show the effectiveness of this new feature set for musical instrument classification. We compare the classification performance with the features constructed from the parameters of generalized Gaussian density and some of the state-of-the-art features using support vector machine classifiers.Article Citation - WoS: 2Citation - Scopus: 2Estimating Probability Density Functions and Entropies of Chua's Circuit Using B-Spline Functions(World Scientific Publishing Co. Pte Ltd, 2012) Savacı, Ferit Acar; Güngör, Mesutn this paper, first the probability density functions (PDFs) of the states of Chua's circuit have been estimated using B-spline functions and then the state entropies of Chua's circuit with respect to the bifurcation parameter have been obtained. The results of the proposed B-spline density estimator have been compared with the results obtained from the Parzen density estimator. © 2012 World Scientific Publishing Company.