Endurance Time Acceleration Functions are specially predesigned intensifying excitation functions that their amplitude increases with time. On the other hand, wavelet transform is a mathematical tool that indicates time variations of frequency in a signal. In this paper, an approach is presented for generating endurance time acceleration functions (ETAFs) whose response spectrum is compatible w...

The performance of Orthogonal Frequency Division Multiple Access (OFDMA) system degrades significantly in doubly dispersive channels. This is due to the fact that exponential sub-carriers do not match the singular functions of this type of channels. To solve this problem, we develop a system whose sub-carriers are chirp functions. This is equivalent to exploiting Fractional Fourier Transform (F...

‎There are different feature extraction methods in brain-computer interfaces (BCI) based on Steady-State Visually Evoked Potentials (SSVEP) systems‎. ‎This paper presents a comparison of five methods for stimulation frequency detection in SSVEP-based BCI systems‎. ‎The techniques are based on Power Spectrum Density Analysis (PSDA)‎, ‎Fast Fourier Transform (FFT)‎, ‎Hilbert‎- ‎Huang Transform (H...

Wavelet analysis is an exciting new method for solving difficult problems in mathematics, physics, and engineering, with modern applications. Wavelet transform of a function is the improved version of Fourier transform. In conventional Fourier transform, we use sinusoids for basis functions. It can only provide the frequency information. Temporal information is lost in this transformation proce...

The S transform is variable window of short time Fourier transform (STFT) or an extension of wavelet transform (WT). It is based on a scalable localizing Gaussian window and supplies the frequency dependent resolution. In this tutorial, we introduce the fundamental function of S transform and the generalized S transform. Furthermore, we present some applications of S transform: seismogram analy...

The improvement in the temporal resolution of seismic data is a critical issue in hydrocarbon exploration. It is important for obtaining more detailed structural and stratigraphic information. Many methods have been introduced to improve the vertical resolution of reflection seismic data. Each method has advantages and disadvantages which are due to the assumptions and theories governing their ...

This paper deals with the performance of the use of fractional Fourier transform (FRFT) instead of conventional Fourier transform (FFT) in either symbol timing offset (STO) and carrier frequency offset (CFO) estimation. Orthogonal frequency division multiplexing is widely used in many systems due to advantages of theses technique compared with mono-carrier systems. In spite of his advantages, O...

most geologic changes have a seismic response but sometimes this is expressed only in certain spectral ranges hidden within the broadband data. spectral decomposition is one of the methods which can be utilized to help interpreting such cases. there are several time-frequency methods including: short-time fourier transform (stft), continuous wavelet transform (cwt), wigner-ville distribution (w...