查询词典 finite difference approximation

Soybean planted in the yellow brown soil, althongh they had big difference in nodule numbers caused by different inoculation methods, there were no difference in the fresh shoot weight because of the poor nutritional conditions. Soybean planted in the brown soil, the difference between different inoculations and fresh shoot weight were obviously because of the balance nutritional conditions. Although there were big difference in nodule numbers when soybean were planted in the peat, there were no difference in the fresh shoot weight, this might be caused by peat, the peat were not a natural soil type and the nutritional conditions might be unbalance.

分期采样的结果表明，黄棕壤中栽种的大豆，虽然接种根瘤菌对结瘤作用有较大的影响，但由于黄棕壤的肥力状况欠佳，而对豆科植物地上部分生长的影响未显出作用；棕壤土中栽种的豆科植物，接种根瘤菌在结瘤方面和植物地上部分生长方面，由于土壤肥力状况较为平衡，均表现出明显的效果；草炭土中生长的豆科植物在结瘤方面虽然表现出较大差异，但由于这种土壤的肥力状况不适于豆科植物的生长，而使地上部的生长也未形成统计上的差异。

Firstly, edge extracting is conducted with a laplace operator for a k frame image of fk and a k-1 frame image of fk-1 collected by a camera; secondly, difference calculus is conducted for images of two frames whose edge is extracted, and a difference image of D is obtained; thirdly, average filtering and binary processing is conducted for the difference image of D, fourthly, the image which is processed of binary is judged, i.e. when the difference of a pixel in the difference image is more than the set threshold value, the pixel is confirmed as a target pixel; otherwise, the pixel is a static background pixel.

首先对摄像头采集的第k帧图像f k和第k-1帧图像f k-1分别采用laplace算子进行边缘提取，然后对经过边缘提取的两帧图像进行差分运算，得到差分图像D，然后对差分图像D进行均值滤波和二值化处理，最后对二值化后的图象进行判断，即认为当差分图像中某一个像素的差大于设定的阈值时，则认为该像素是目标像素，反之则认为是静止不动的背景像素。

The effects of the initial values and the network approximation error using neural network model composed of feedforward neural net and delayed output feedback in the approximation of NARMAX system are studied, and a conclusion is drawn that under some weak conditions the output of the network model has little difference from that of the actual system.

研究了用带有延迟环节的前馈网组成的网络模型逼近NARMAX系统时网络逼近误差及运行初始误差对网络模型输出的影响，指出在一些弱的条件下网络模型输出与实际系统输出间相差不大。

Paraxial approximation absorption boundary condition based on acoustic wave equation can obtain better absorption results by increasing paraxial approximation order of Taylor series. However, this kind of operation will increase the complexity of difference computation, and result in instability of computation process.

基于声波波动方程的旁轴近似吸收边界条件可以通过提高泰勒级数展开的旁轴近似阶数获得更好的吸收效果，但这样不仅增加了差分计算的复杂性，同时还导致计算过程不稳定。

The difference of results under two approximations-high order approximation and paraxial approximation are also given.

最后用计算机绘制了列阵成像系统中各观察面上的场强分布。

The method includes dividing a digital image, formed from M rows and N columns of pixels, into a plurality of band-shaped areas by partitioning at each of a prescribed number of rows; averaging, for each column, the gradation values of pixels in said band-shaped areas for each of said plurality of band-shaped areas; computing an approximation line which approximates, in each of said plurality of band-shaped areas, a distribution of said average of gradation values; and judging whether there exists a succession of d columns at which the difference between said gradation value derived from said approximation line and said average of gradation values for each column exceeds a prescribed threshold.

该方法包括：通过以规定行数为单位进行分割，将由M行N列个像素形成的数字图像划分为多个带状区域；对于所述多个带状区域的每一个，针对各列来对所述带状区域中的像素的浓淡值求平均；计算近似线，该近似线在所述多个带状区域的每一个中近似于所述浓淡值的平均值的分布；并且判断是否存在如下连续的d个列，在所述连续的d个列中，从所述近似线得到的所述浓淡值与针对各列的所述浓淡值的平均值之间的差值超出一指定阈值。

This thesis contributed to the comprehensive study of the Finite-Difference Time-Domain method and its application to the numerical computation of radiated electromagnetic fields in switched mode power supplies. The work includes mainly three parts: the study on the performance of PML absorbing boundary condition applied to pseudo low frequency electromagnetic problems; the validation of the FDTD method with PML absorbing boundary conditions and the corresponding computer software based on the numerical study of the electromagnetic field of an electric dipole antenna, and its application to the numerical computation of radiated electromagnetic fields in switched mode power supplies; the development of an improved alternating direction implicit finite-difference time-domain method.

在综合前人工作基础上，本文对时域有限差分法及其在开关电源辐射电磁场数值计算中的应用进行了系统的分析和研究，其核心内容包括：伪低频电磁场数值计算中PML吸收边界条件性能的研究；基于基准问题—电偶极子天线三维辐射电磁场，验证了本文构造的基于PML吸收边界条件的三维FDTD法及其计算软件，并应用于高频开关电源辐射电磁场的数值分析；提出了一种改进的交替方向隐格式时域有限差分法。

The main idea of the finite difference method is as follows: We consider the discrete difference equation with the finite alphas as approximate substitution for the differential equation with the continuous variant and boundary conditions.

有限差分方法的基本思想是用离散的，只含有有限个未知数的差分方程去近似代替连续变量的微分方程及边界条件，并把相应的差分方程解作为微分方程的近似解。

Within this context, four specific areas are addressed:(1) By means of finite integration technique, a new kind of the first order partial difference equation is derived from the original disperse transmission line equation of the uniform waveguide's. As it is the kind of one dimension Dirichlet's boundary problem, it is convenient for us to solve this equation from the leapfrog scheme. Because computation is carried out in one dimension, both high calculation efficiency and precision have been obtained in this method. Meanwhile, this method provide us a different selection to simulate the transient response of waveguide with non-simplical, for examples cylinder and elliptic waveguide, and avoid solving the second order equation, or using finite difference time domain to simulate a three dimension problem, sometimes the latter precision is not satisfied with the need, or low efficiency.

在这一研究内容下，主要研究四个方面的问题：(1)在完成金属波导传输线方程时域形式的基础之上，应用有限积分技术，把波导特征模式的色散传输线方程，化简为一组新的一阶偏微分方程组，该边值问题属一维Dirichlet边值问题，从而便于用蛙跳格式求解，由于是在一维中计算，该方法具有很高计算效率和精度，从而避免了以往为得到金属波导中特征模的时域响应特性，须要求解二阶方程，或用时域有限差分方法求解三维问题的方法，对于后者来说，计算有时是不准确的，或是很耗时的例如计算诸如圆波导、椭圆波导等其它复杂形状的波导。

There are many ways to analysis and computation of Mikthw's two rotations equation,finite difference method is the most one while using the finite difference method,a flood of data need be collected and computed.

而在目前高性能计算机系统中，最广泛使用的并行环境是MPI(Message Pass-ing Interface)，它已成为一种并行程序的标准。

The studies on the developing of new media are very important to the increasing of the area density of HDD and to the implementation of hybrid recoding technology.

光磁混合记录方法，是一种可以突破超顺磁极限的限制，并进一步提高硬盘记录密度和读写速率的一种新型超高密度信息存储方式。

In io, mTOR inhibition promotes T cell anergy under conditions that would normally induce priming.

体内研究中，在正常可激发免疫反应的条件下，抑制mTOR可促使T细胞无能。