Th is method contains three dimensional coupling difference scheme with high accur acy and high resolution, and the high order time splitting methods.

A method of extracting instantaneous frequency of LFM signal is presented,according to which signal is de-noised via wavelet analysis firstly,the instantaneous phase sequence is acquired secondly,lastly the instantaneous frequency is extracted with high-order difference.

According to structural feature of typical geologic models in Shengli oilfield, the paper presented staggering mesh high-order difference forward simulation of density-variated acoustic equation.

I describe some high-order difference methods for wave equation approximation in structure and velocity images,point out their stability conditions and analyse the frequency dispersion error, Free coefficient nodes are used in difference approximation to improve computation stability.

Use of higher-order difference equations can reduce numerical dispersion and calculation errors of wave equation finite-difference time-domain(WEFDTD) method.

In this paper,we give a probability algorithm for several key stream sequence generators using higher order differential, which can find quickly the feedback polynomial using the known plaintext,and it can still succeed possibly using ciphertext only if the plaintext is umbalanced.

We give a probability algorithm for feedforward key stream sequence generators using higher order differential that it can find quickly feedback polynomial using known plaintext,and it succeed possibly using ciphertext only if plaintext isn’t balance.

The advanced integral concept its advanced derivative,and its generalization and application areintroduces,resulting in the theorem.

The paper introduces the advanced integral,following the advanced derivative,and its generaliza- tion and application,and at last arrives at the theorem.