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.
讨论一种在低信噪比条件下提取LFM信号瞬时频率的方法,即先对信号进行小波去噪处理,再求得信号的瞬时相位序列,最后利用高阶差分的方法求取瞬时频率。
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.
根据胜利油田典型地质模型的构造特点,本文提出了变密度声波方程交错网格高阶差分正演方法。
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.
理论分析表明，在构造与波速成像中采用高阶差分方法，可以减小频散误差、提高计算效率与计算精度、获得满意的效果。
Use of higher-order difference equations can reduce numerical dispersion and calculation errors of wave equation finite-difference time-domain(WEFDTD) method.
采用高阶差分格式能有效地减小波动方程时域有限差分法(WEFDTD)的数值色散和计算误差。
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.
本文运用高阶差分的思想对两类密钥流生成器给出了一种概率攻击算法:即在已知明文攻击时,能较快地求出其反馈多项式的抽头;对于唯密文攻击,只要明文非平衡,则该算法仍然有望成功。
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.
运用高阶差分的思想,对前馈密钥流生成器给出了一种概率攻击算法:即在已知明文攻击时,能较快地求出其反馈多项式的抽头;对于唯密文攻击,只要明文非平衡,则该算法仍然有望成功。
Then the article discusses forward modeling based on acoustic wave higher difference, then analyzes numerical dispersion including time and spatial dispersion and presents its stability conditions.
接着,简要介绍了基于声波高阶差分的多次波正演模拟方法,分析了这种方法的数值频散问题,包括时间和空间频散,同时给出了它的稳定性条件。
The high-order difference method of wave equation has the advantages of high accuracy and small numerical dispersion.
波动方程高阶差分法具有精度高、数值频散小的优点 。
Asymptotic Behavior of Solutions of Certain Higher Differential Equations and Higher Difference Equations;
一类高阶微分方程及高阶差分方程解的渐近性
High-Order Difference Schemes of Exponential Type for Convection Diffusion Equation with Source Term;
对流扩散方程的指数型高阶差分格式
The Study of Oscillatory Theory of Higher-Order Difference Equations and Second-Order Dynamic Equations on Time Scales;
高阶差分方程及时标上二阶动力方程的振动性理论研究
The Efficient High-Order Finite-Difference Scheme for 2-D Reaction-Diffusion Equations;
二维反应—扩散方程的实用有效的高阶差分格式
The Existence of Periodic and Subharmonic Solutions of Several Classes of Higher Order Difference Equations;
几类高阶差分方程周期解与次调和解的存在性
A Practical and Effective Algorithm of Higher-order Difference of Parabolic Equation;
抛物型方程的一个实用有效的高阶差分算法
Asymptotic behavior and existence of positive solutions for a class of higher order neutral difference equations;
一类高阶差分方程正解的存在性及渐近性质
A Fourth-Order Compact Finite Difference Method for Higher-Order Lidstone Boundary Value Problem;
高阶Lidstone边值问题的四阶紧有限差分方法
Absolutely Stable Explicit Difference Scheme for Sloving Parabolic Equation of Higher Order
高阶抛物型方程恒稳的显式差分格式
The Calculation of the Seismic Wave-field with High-order Staggered-grid Finite-difference Scheme;
高阶交错网格有限差分地震波场计算
The Qualitative Study of Several Kinds of Higher Order Nonlinear Difference Equations;
几类高阶非线性差分方程的定性研究
A High Order Parallel Difference Scheme of Parabolic Equation
抛物型方程的一种高阶并行差分格式
Analysis of Ocular Higher-order Aberrations in Refractive Amblyopia
高阶像差在屈光性弱视中的评价分析
A High Order 2D-FDFD Method for Guided Wave Structures
应用高阶二维频域有限差分方法分析导波结构
Absolutely Stable Difference Schemes of High Accuracy for solving Four Order Parabolic Equation
解四阶抛物型方程的绝对稳定高精度差分格式
High-Order Compact Finite Difference Method for Systems of Nonlinear Reaction-Diffusion Equations;
非线性反应扩散方程组的高阶紧有限差分方法
Global Asymptotic Stability for the Higher Order Rational Difference Equations;
几类高阶有理差分方程的全局渐近稳定性
Computation of matrix higher power and its application in difference systems;
矩阵高阶幂的计算及其在差分方程中的应用