Image classification was performed using Gabor wavelet filters for image feature extraction, self-organising maps (SOM) for dimensional reduction of Gabor wavelet filters, and forward (FNN), Hermite (HNN) and Laguerre (LNN) neural networks to classify real and artificial fingerprint images from optical coherence tomography (OCT). Use of a SOM after Gabor edge detection of OCT images of fingerpr...

The influence of the number of Discrete Wavelet Transform (DWT) iterations on a wavelet OFDM (WOFDM) system performance is studied in this paper. The WOFDM transmission is tested on a flat, time variant radio channel. Basically, the number of DWT iterations coincides with the number of transmission scales used. Our simulations show that by increasing the value of this parameter, the BER perform...

Summary Wavelets provide the flexibility for analysing stochastic processes at different scales. In this article we apply them to multivariate point as a means of detecting and unknown nonstationarity, both within across component processes. To statistical tractability, temporally smoothed wavelet periodogram is developed shown be equivalent multi-wavelet periodogram. Under stationarity assumpt...

Radar images can show great variability from pixel to pixel, which is an obstacle to effective processing. This variability, due to speckle created by the radar wave coherence, necessitates the use of more adapted filters. Previous studies have shown that multiresolution wavelet analysis yields better results but produces artefacts due to multiscale decomposition. This paper proposes a method t...

The different regions of the brain have to interact to perform language processing. Such neural integration processes can be studied by measuring the synchronization of the brain signals. The purpose of this examination was to study the word fluency when one group, the Experiment group, generates word which begun by letters “A”,”B”,”F”, ”I”,”K”,”M”,”S”,”T” ,”U”. Every individual in the “Experim...

Wavelet power spectrum (WPS) and wavelet coherence analyses (WCA) are used to examine the co-movements among oil prices, green bonds, CO2 emissions on daily data from January 2014 October 2022. The WPS results show that returns exhibit significant volatility at low medium frequencies, particularly in 2014, 2019–2020, Also, Green Bond Index presents end of 2019–2020 beginning 2022 low, medium, h...

This paper presents a new filtering approach for Synthetic Aperture Radar (SAR) interferometric phase noise reduction in the shearlet domain, depending on the coherent statistical characteristics. Shearlets provide a multidirectional and multiscale decomposition that have advantages over wavelet filtering methods when dealing with noisy phase fringes. Phase noise in SAR interferograms is direct...

Abstract. This paper investigates in detail a possible mechanism of energy convergence leading to freak waves. We give examples of a freak wave as a (weak) pseudo-maximal wave to illustrate the importance of phase coherence. Given a time signal at a certain position, we identify parts of the time signal with successive high amplitudes, so-called group events, that may lead to a freak wave using...

We show that chaotic states situated in the proximity of periodic windows in bifurcation diagrams are eligible for the observation of coherence resonance. In particular, additive Gaussian noise of appropriate intensity can enhance the temporal order in such chaotic states in a resonant manner. Results obtained for the logistic map and the Lorenz equations suggest that the presented mechanism of...