2) fourth-order exponential difference scheme
四阶指数差分
1.
A fourth-order exponential difference scheme and it s applications in FDTD;
四阶指数差分及其在FDTD中的应用
3) fourth-order compact difference scheme
四阶紧致差分格式
1.
Impact of fourth-order compact difference scheme on computational properties of 3D grids;
四阶紧致差分格式对三维网格计算特性的影响
4) first order differential
一阶差分
1.
The classical moving average technique and first order differential were used for segmentation.
先采用移动平均法(moving average,MA)和一阶差分法确定SEMG信号中对应的每个动作波形的起止点,再利用递归量化分析(recurrence quantifica-tion analysis,RQA)方法提取各种动作波形的非线性特征参量(确定率、递归率等),由两路SEMG信号的这些特征参量构成特征矢量,输入BP(back propagation)神经网络,完成对不同动作的分类。
2.
Combined with the first order differential algorithm, this method has solved the problem successfully.
针对双电位器式传感器检测系统存在的跳区现象，提出了一种新的判区方法，并结合一阶差分算法成功地解决了跳区问题，同时也提高了系统的抗干扰能力。
5) 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。
6) first difference
一阶差分
1.
At the meantime,during the procedure of pre-processing,according to the character that the illumination conditions on the scene of the expressway toll collection frequently change a lot,the algorithm of first difference combining the method of fixing the threshold of binarization via accumulating the points was used to complete the job of extracting the outline of the image.
在图像预处理过程中,根据高速公路收费站点光照条件不断变化的特点,采用一阶差分算法并结合累积像素点确定二值化阈值的方法,完成图像边缘轮廓的提取工作。
2.
Realizing of algorithm of composite data filter and eliminating singular term using first difference method in data collection and processing were analyzed and calculation results were given.
介绍了建材检测微机控制系统总体结构,详细分析了数据采集与处理过程中复合数据滤波、一阶差分法剔除奇异项算法的实现过程,给出了计算结果。
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