Electrical - Electronic Engineering / Elektrik - Elektronik Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/11
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Conference Object Citation - WoS: 1Citation - Scopus: 2Dalgacık Tepeleri Kullanarak İ̇şaretlerin Bileşenlerine Ayrılması(Institute of Electrical and Electronics Engineers Inc., 2007) Özkurt, Nalan; Savacı, Ferit AcarÇok bileşenli durağan olmayan bir işaretin enerjisi tüm zaman-frekans alanına yayılır. Kaynak ayrıştırma gibi bazı uygulamalarda, işaretin farklı zaman-frekans özelliklerine sahip bileşenlerini ayırmak gerekli olabilir. Bu çalışmada, çok bileşenli durağan olmayan bir işaretin dalgacık tepeleri bulunarak bu tepeleri oluşturan doğrular Hough dönüşümünü kullanılarak saptanmış ve analitik olarak modellenmiştir. Her bir doğru parçasına ait işaret bileşeni ayrı ayrı yeniden elde edilmiştir.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: 6Citation - Scopus: 7Reconstruction of Nonstationary Signals Along the Wavelet Ridges(World Scientific Publishing Co. Pte Ltd, 2006) Özkurt, Nalan; Savacı, Ferit AcarIn this paper, the nonstationary signals have been recovered using the skeleton along the wavelet ridges in the noisy case and the attractors of the cleaned signals are reconstructed in the phase space by time-delay embedding. In order to verify the signal recovery and reconstruction procedure, the similarity measure Hausdorff distance between cleaned, noise-free original attractors have been calculated. The computations show that the procedure reduces the noise level acceptably and the reconstructed attractors are more similar to the original attractors.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: 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.Article Citation - WoS: 21Citation - Scopus: 37Determination of Wavelet Ridges of Nonstationary Signals by Singular Value Decomposition(Institute of Electrical and Electronics Engineers Inc., 2005) Özkurt, Nalan; Savacı, Ferit AcarThe ridges obtained from chaotic signals can give the relevant information about the phase structures of the dynamical systems. Therefore, a new wavelet ridge determination method for the noisy signals and nonstationary signals, which is based on the singular value decomposition (SVD) has been proposed in this paper. The proposed method has been compared with Carmona method for monocomponent signals, and multicomponent signals. The proposed method is computationally more effective than the Carmona method to determine the actual ridges. Also, the ridges of the periodic limit cycles and chaotic attractors have been determined by using the SVD-based method to find the degree of chaoticity.Article Citation - WoS: 14Citation - Scopus: 14The Circuit Implementation of a Wavelet Function Approximator(Springer Verlag, 2002) Özkurt, Nalan; Savacı, Ferit Acar; Gündüzalp, MustafaThis paper describes the analog synthesis of a wavelet function approximator using sigmoidal mother wavelet. Any finite energy multivariate function can be approximated by this analog circuit using the multiresolution approximation property of the wavelet decomposition. The approximator circuit includes bipolar junction transistors, operational amplifiers and linear passive circuit elements.