Based on the sea ice grade, sea ice area and monthly atmospheric circulation index time series, wavelet and cross-wavelet methods are employed to investigate the long- term variation characteristics and climatic mechanism of sea ice in the Bohai Sea and the North Huanghai Sea.

A short-cut method of constructing Daubechies biorthonormal wavelet with even symmetry double scale parameter;

The extended matrix corresponding to multiple channelorthonormal wavelet filters is also obtained in this paper, which solves the problem of the general solutions of matrixextension associated with multiple channel orthonormal wavelet filters systematically.

Compactly supported orthonormal wavelet, compactly supported biorthogonal wavelet, and B spline wavelet, etc.

Choosing proper orthogonal wavelet function,the low frequency sub-band was enhanced obviously and the high frequency sub-band was restrained moderately to realize image enhancing via the modulation of information entropy window.

The construction of the B-spline wavelet is simple, and it has better stability than the orthogonal wavelet.

On the basis of wavelet transform technique and OFDM modulation technique, an technique substituting multi-scale orthogonal wavelet for cosine function in OFDM for the optimiza- tion design of system is proposed.