1) centered schemes of finite difference
高阶中心差分
2) two-order center scheme
二阶中心差分
1.
It is shown that the new scheme has the virtue of high precision without increasing memory requirement compared to two-order center scheme.
与普通的二阶中心差分格式相比,该格式具有在不增加存储量的前提下提高计算精度的优点。
3) high-order difference
高阶差分
1.
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。
2.
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。
3.
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。
4) higher-order difference
高阶差分
1.
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。
5) higher order differential
高阶差分
1.
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。
2.
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。
6) higher difference
高阶差分
1.
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。
补充资料：对称差分(n阶的)
对称差分(n阶的)
symmetric difference of order
对称差分(n阶的)l另11111州tric山ffer曰℃eof份der‘c“MMe邓一，ecK即pa3Hoc几“op，皿Kan」，一元实变函数f在点x上的 表达式 声/n、，.、。，/.n一Zk八 △口ffx，h)=)l:’1(一1)“f lx十二二~一竺二生h 1. 一‘““一””k饥戈k/、‘产“戈一2‘’/‘将h换成Zh，下面的表达式也称为对称差分: 息川(一1)*，‘二+、。一2、)。).假若f(x)在x有n阶导数厂时(x)，那么 △二f(x，h)=./戈n)(x)h”+o(h”). T .fl .J’IyKame皿。撰
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参考词条