this paper presents a modified digital image watermarking method based on nonnegative matrix factorization. firstly, host image is factorized to the product of three nonnegative matrices. then, the centric matrix is transferred to discrete cosine transform domain. watermark is embedded in low frequency band of this matrix and next, the reverse of the transform is computed. finally, watermarked ...

Microring resonators (MRRs) can be used to generate optical millimetre-wave solitons with a broadband frequency of 40–60 GHz. Non-linear light behaviours within MRRs, such as chaotic signals, can be used to generate logic codes (digital codes). The soliton signals can be multiplexed and modulated with the logic codes using an orthogonal frequency division multiplexing (OFDM) technique to transm...

In this paper, some time-frequency analysis methods were studied to get the detailed characteristics of two-way automatic communication system (TWACS) outbound signal sampled from industry power network with high disturbance, . Compared with traditional time-domain detecting algorithm, time-frequency analysis methods, including short-time Fourier transform (STFT)), Wigner distribution (WD) and ...

The properties of the Gabor and Morlet transforms are examined with respect to the Fourier analysis of discretely sampled data. Forward and inverse transform pairs based on a fixed window with uniform sampling of the frequency axis can satisfy numerically the energy and reconstruction theorems; however, transform pairs based on a variable window or nonuniform frequency sampling in general do no...

Streaming video quality dependents in part upon the video encoding process. The Frequency Domain Motion Estimation process is commonly used to accelerate the entire video encoding process. It is used to reduce the encoding time by increasing the Motion Estimation Time Saving. The Combinational-Discrete Cosine Transform consumes most of the time of the Frequency Domain Motion Estimation video en...

The most popular time-frequency analysis tool, the Short-Time Fourier Transform, suffers from blurry harmonic representation when voiced speech undergoes changes in pitch. These relatively fast variations lead to inconsistent bins in frequency domain and cannot be accurately described by the Fourier analysis with high resolution both in time and frequency. In this paper a new analysis tool, cal...

The orthogonal frequency division multiplexing is used in wireless communication due to high data rate. OFDM are robustness against multi-path fading, frequency selective fading, and narrow band interference. Wavelet analysis has strong advantages over fourier transform and also allows time-frequency domain operation with flexibility. Wavelet is applied in various fields of wireless communicati...

Keywords: fractal geometry, fractional derivative, fractional Fourier transform, fractional power of a matrix, self similarity, complex partial differential equation, broadband ultrasound, frequency-dependent attenuation, time domain. 1. Backgrounds The rational behind this model is schematically illustrated below: Fractal geometry (irregular soft tissues) → Fractional Fourier transform (freque...

We present a numerical study of the resolution power of Padé Approximations to the Z-transform, compared to the Fourier transform. As signals are represented as isolated poles of the Padé Approximant to the Z-transform, resolution depends on the relative position of signal poles in the complex plane i.e. not only the difference in frequency (separation in angular position) but also the differen...

Recently, the Meyer wavelet packets transform (MWPT), the harmonic wavelet transform (HWT), and the S-transform have been used to process recorded earthquake induced strong ground motions (GMs) in various earthquake engineering and engineering seismology applications. In this paper, the potential of these three wavelet-based time-frequency representation (TFR) techniques to identify and to char...