Electrical - Electronic Engineering / Elektrik - Elektronik Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/11
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Article Citation - WoS: 8Citation - Scopus: 8Wavelet Ridges for Musical Instrument Classification(Springer Verlag, 2012) Özbek, Mehmet Erdal; Özkurt, Nalan; Savacı, Ferit AcarThe time-varying frequency structure of musical signals have been analyzed using wavelets by either extracting the instantaneous frequency of signals or building features from the energies of sub-band coefficients. We propose to benefit from a combination of these two approaches and use the time-frequency domain energy localization curves, called as wavelet ridges, in order to build features for classification of musical instrument sounds. We evaluated the representative capability of our feature in different musical instrument classification problems using support vector machine classifiers. The comparison with the features based on parameterizing the wavelet sub-band energies confirmed the effectiveness of the proposed feature. © 2011 Springer Science+Business Media, LLC.Article Citation - WoS: 36Citation - Scopus: 44Continuous Time Wavelet Entropy of Auditory Evoked Potentials(Elsevier Ltd., 2010) Çek, Mehmet Emre; Özgören, Murat; Savacı, Ferit AcarIn this paper, the continuous time wavelet entropy (CTWE) of auditory evoked potentials (AEP) has been characterized by evaluating the relative wavelet energies (RWE) in specified EEG frequency bands. Thus, the rapid variations of CTWE due to the auditory stimulation could be detected in post-stimulus time interval. This approach removes the probability of missing the information hidden in short time intervals. The discrete time and continuous time wavelet based wavelet entropy variations were compared on non-target and target AEP data. It was observed that CTWE can also be an alternative method to analyze entropy as a function of time. © 2009 Elsevier Ltd. All rights reserved.Article Citation - WoS: 4Citation - Scopus: 5The Implementation of Nonlinear Dynamical Systems With Wavelet Network(Urban und Fischer Verlag GmbH und Co. KG, 2006) Özkurt, Nalan; Savacı, Ferit AcarA dynamic wavelet network circuit implementation for modelling the nonlinear dynamical networks has been proposed in this study. The dynamical wavelet network includes static wavelet network with Mexican hat wavelet function, the voltage-controlled switches and capacitors. The circuit simulations have been done in Spice for the period-1 limit cycle, the spiral and double scroll attractors of the Chua's circuit.Article Citation - WoS: 2Citation - Scopus: 2Determination of the Stationary State Densities of the Stochastic Nonlinear Dynamical Systems(Elsevier Ltd., 2006) Günel, Serkan; Savacı, Ferit AcarThe stationary state probability densities appear not only in the study of dynamical systems with random vector fields, but also in the deterministic dynamical systems exhibiting chaotic behavior when the uncertainties in the initial conditions are represented with the probability densities. But since it is very hard problem to determine these densities, in this paper the new efficient method to obtain an approximate solution of Fokker-Planck-Kolmogorov equation which arises in the determination of the stationary state probability densities has been given by representing the densities with compactly supported functions. With specific choice of the compactly supported functions as piecewise multivariable polynomials which are supported on the ellipsoidal regions, the parameters to be calculated for determining the densities can be considerably decreased compared to Multi-Gaussian Closure scheme, in which the stationary densities are assumed to be the weighted average of the Gaussian densities. The main motivation to choose the compactly supported functions is that, in the chaotic dynamics the states are trapped in a specific compact subspace of the state space. The stationary state densities of two basic examples commonly considered in the literature have been estimated using the Parzen's estimator, and the densities obtained using the newly proposed method have been compared with these estimated densities and the densities obtained with the Multi-Gaussian Closure scheme. The results indicate that the presented compactly supported piecewise polynomial scheme can be successful compared to Multi-Gaussian scheme, when the system is highly nonlinear.Article Citation - WoS: 2Citation - Scopus: 3The System Modelling and Circuit Implementation From Time-Frequency Domain Signal Specifications(Urban und Fischer Verlag GmbH und Co. KG, 2008) Savacı, Ferit Acar; Özkurt, NalanThe system modelling and the circuit implementation of the nonlinear circuits using the wavelet domain techniques has been accomplished in this study. When the time-frequency domain specifications have been given as the wavelet ridges, the signal with the given ridges has been synthesized. Then, the dynamical wavelet network has been trained for the synthesized signal. The circuit of the wavelet network has been designed and simulated. © 2007 Elsevier GmbH. All rights reserved.Article Citation - WoS: 5Citation - Scopus: 5The Circuit Realization of Mexican Hat Wavelet Function(Urban und Fischer Verlag GmbH und Co. KG, 2005) Özkurt, Nalan; Savacı, Ferit Acar; Gündüzalp, MustafaA wavelet network circuit implementation for Mexican Hat mother wavelet has been proposed for nonlinear function approximation which can also be used for the realization of the algebraic nonlinear components. The Mexican Hat mother wavelet function has been implemented with discrete circuit components and it has been observed that the experimental waveform obtained from the realized circuit is approximately same as the Spice simulation of the original function. The circuit simulations of exemplar functions implemented in Spice are also given. © 2004 Elsevier GmbH. All rights reserved.