A new approach for frequency analysis of recorded signals and readout the frequency of harmonics is presented in the paper. The main purpose has been achieved by the cross-correlation function and Hilbert transform. Using the method presented in the paper, there is another possibility to observe and finally to identify single harmonic apart from commonly used Fourier transform. Identification o...

In order to identify the natural frequency of ship propulsion shafting under running condition, a multi-method approach that combines Duffing Oscillator, harmonic wavelet packet transform, and probability density function is proposed. An experimental investigation on conducted test bench, response different alignment states obtained from measured bearing vibration signal. The results show can b...

[1] Recognizing that the frequency distribution of annual maximum floods at a given location may change over time in response to interannual and longer climate fluctuations, we compare two approaches for the estimation of flood quantiles conditional on selected ‘‘climate indices’’ that carry the signal of structured low-frequency climate variation, and influence the atmospheric mechanisms that ...

We give a new characterization of the Gelfand triple of function spaces in (S0, L, S′ 0) by means of a family of time-frequency localization operators. The localization operators are defined by the short-time Fourier transform and determine the local time-frequency behavior, whereas the global timefrequency distribution is characterized by a sequence space norm. We also show that the alternativ...

We demonstrate the usefulness of some signalprocessing tools for the EISCAT data analysis. These tools are somewhat less classical than the familiar periodogram, squared modulus of the Fourier transform, and therefore not as commonly used in our community. The first is a stationary analysis, ‘‘Thomson’s estimate’’ of the power spectrum. The other two belong to time-frequency analysis: the short...

Last years, Wavelet Packet Modulation (WPM) or Wavelet Packet Transform based Orthogonal Frequency Division Multiplexing (WPT-OFDM) have been introduced to wired and wireless communication fields as efficient Multicarrier Modulation (MCM) techniques. The wavelets have interesting features such as flexibility, compatibility and localization in both time and frequency domains with no need to use ...

Energy concentration of the S-transform in the time-frequency domain has been addressed in this paper by optimizing the width of the window function used. A new scheme is developed and referred to as a window width optimized S-transform. Two optimization schemes have been proposed, one for a constant window width, the other for time-varying window width. The former is intended for signals with ...

The basis functions of the continuous fractional Fourier transform (FRFT) are linear chirp signals that are suitable for time-frequency analysis of signals with chirping timefrequency content. Efforts to develop a discrete computable version of the fractional Fourier transform (DFRFT) have focussed on furnishing a orthogonal set of eigenvectors for the DFT that serve as discrete versions of the...

Partition functions Z(x) of statistical mechanics are generally approximated by integrals. The approximation fails in small cavities or at very low temperature, when the ratio x between the energy quantum and thermal energy is larger or equal to unity. In addition, the exact calculation, which is based on number theoretical concepts, shows excess low frequency noise in thermodynamical quantitie...

In this paper, we derive analytical expressions describing spectral and mutual densities of random processes by performing Fourier transform the corresponding correlation functions. On basis accepted for functions differentiable processes, density components, which is a complex frequency function, are derived. The influence on functions, densities, components (real, imaginary, amplitude, phase)...