In wavelet-based image coding, a variety of masking properties have been exploited that result in spatially-adaptive quantization schemes. It has been shown that carefully selecting uniform quantization step-sizes across entire wavelet subbands or subband codeblocks results in considerable gains in efficiency with respect to visual quality. These gains have been achieved through analysis of wav...

this paper presents a new coding method for image compression based on jpeg2000 and contourlet transform. jpeg2000 standard is a common standard that uses discrete wavelet transform (dwt) in the compression process. the main problems of dwt are failure to detect curved edges in image and its shortage representation of the ridge and furrow patterns which cause deficiency and block artifacts rema...

Elementary processes of two-dimensional (2D) turbulence have been examined by extensive analyses of finescale structures in the density distribution of a magnetized pure electron plasma that evolves from an unstable initial state to a single-peaked stable distribution through successive mergers of vortex patches. Fourier-based analyses have revealed that the spectral dynamics in the wave-number...

BACKGROUND Over 90 years after its first recording, scalp electroencephalography (EEG) remains one of the most widely used techniques in human neuroscience research, in particular for the study of event-related potentials (ERPs). However, because of its low signal-to-noise ratio, extracting useful information from these signals continues to be a hard-technical challenge. Many studies focus on s...

An accurately evaluate about the zone number and position of the gas zone is put forward in this paper. It provides the reliable basis for developing natural gas through synthetically analyzing the result of carrying on wavelet de-noising and wavelet package denoising disposal simultaneously to the density porosity curve and neutron porosity curve. If there is natural gas in the void of undergr...

Clusters of galaxies form by gravitational collapse and accretion of subgroups under the influence of gravity. Analyses of the gas thermal structure within clusters obtained from X-ray observations reveals us the underlying dark matter structure and dynamics, provided that the baryonic physics is well understood. We use hydrodynamical N-body simulations of galaxy clusters evolving in cosmologic...

The notion of a weak multiresolution analysis is defined over an arbitrary field in terms of cyclic modules for a certain affine group ring. In this setting the basic properties of weak multiresolution analyses are established, including characterizations of their submodules and quotient modules, the existence and uniqueness of reduced scaling equations, and the existence of wavelet bases. Thes...

we present here the numerical solution of damped forced oscillator problem using haar wavelet and compare the numerical results obtained with some well-known numerical methods such as runge-kutta fourth order classical and taylor series methods. numerical results show that the present haar wavelet method gives more accurate approximations than above said numerical methods.

introduction: evoked potentials arisen by stimulating the brain can be utilized as a communication tool  between humans and machines. most brain-computer interface (bci) systems use the p300 component,  which is an evoked potential. in this paper, we evaluate the use of the hidden markov model (hmm) for  detection of p300.  materials and methods: the wavelet transforms, wavelet-enhanced indepen...