近似误差

Firstly, the isotropic difference templates were introduced to approximate the differential in the ADI-FDTD method, and the weighting coefficients of difference terms were determined for implementing isotropic numerical dispersion; Then the permittivity and permeability were adjusted manually to reduce the numerical dispersion error in any directions. Therefore the simulation accuracy and efficiency can be improved effectively for time domain problems with some finite bandwidths.

该方法在ADI-FDTD方法的差分近似微分中引入各向同性差分模板，并通过确定各向同性差分的加权系数来近似实现各向同性，然后人为修正空间的介质参数来减少各个方向上的数值色散误差，因此在模拟一定带宽的时域问题时可有效提高计算精度和计算效率。

Since both of them are approximate solutions, attention to the estimation of error has to be paid.

由于这两种解法得到的都是近似解，因此近似解的误差不能不让人关注。

Coefficient distribution of the APIDCSF is similar to that of circular quincunx Neville filter and its interpolating performance outperforms the Neville filters with high orders vanishing moments.The aim of bidimensional interpolating is to diminish the error between the true value and the estimated one.

二维内插的质量是以预测值与真值之间的误差来衡量的，按照最小均方误差的准则，利用二维自相关函数模型和环形内插滤波器的系数分布特点构造了最小均方误差意义上的环形最优内插器，实验证明了全相位离散反余弦内插器近似于最优内插器。

In this paper, we expand the eigenvalue of Poisson equation using nonconforrn-ing Q1rot element. The principal term of error we get is not negative. In general, the approximate eigenvalue is the upper bound, but the approximate eigenvalue may be the lower bound when the principal term is zero.

本论文对Poisson方程的特征值采用方形旋转双线性非协调元Q_1~(rot元进行展开，得出的误差主项大于或等于零，因此在一般情况下近似特征值是上界，但当主项等于零时近似特征值可能是下界。

At the same time, the practical implementation of evolutionary algorithm is given in order that evolutionary algorithm is introduced into vector quantizer. In the fourth section the asymptotic theory of vector quantization is studied. Then the partial distortion theorem that when codebook size is large enough, each region of the partition makes an equal contribution to the distortion for an optimal quantizer, which is the key part of vector quantizer is obtained. Finally, the competitive learning algorithm based on the partial distortion theorem is proposed, which introduces the subdistortion of each region into the distortion measure to assure that the subdistortion of each region approximately equals to each other.

第四章详细研究矢量量化的渐近理论，然后得出了矢量量化器设计的核心部分——部分失真定理，当码本尺寸足够大且输出矢量的渐近概率密度与输入矢量的概率密度的幂成比例时，最优量化器划分的各个区域对该量化器的平均误差产生相同的影响，最后提出基于部分失真定理的竞争学习算法，它通过在误差测度中，引入与各区域相关的子误差以保证各区域的子误差近似相等，该算法实现较为简单，在一定程度上确保全局最优。

Both upper bound formula and lower bound formula of the global truncation error of Euler method have been derived theoretically.After making certain approximat e processing,the derived upper formula changes into current upper bound formula.

从理论上推导出了欧拉方法的整体截断误差的上限公式和下限公式，作一定的近似后，得到的整体截断误差上限公式就变为现用的整体截断误差上限公式。

Now the controllability theory in linear systems over the field R of real numbers has been heavily studied. This theory is efficacious for analyzing the characters which are determined by the value of physical parameters and system structure, nevertheless a practical system has a definite structure and has approximate, even unknown parameter sometimes because of a limit to experiment conditions, or a limit to making technology, the errors of observation. It is inconvenience for a linear system over the field R of real numbers to analyze the structure characters of a physical system, such as structural controllability.

目前，实数域上的系统的完全能控性理论研究已经很成熟了，它用于分析系统结构和物理参量的值共同决定的那些性能是有效的，然而，在工程中，由于实验条件或者制造工艺上的限制和观测上的误差，以及人为地对数据的近似处理，一个实际系统往往其结构是确定的，而参数只是近似的甚至未知的，实数域上的系统不便于分析物理系统的结构性质，如结构能控性。

One position control system is introduced as the objective controlled by FOC. Based on Mittag-Leffler function, the fractional order control system with full memory length is adopted as evaluation criterion, and an approximation performance function of discretization methods is proposed. Analyzing the time domain error and approximation performance, the investigation to various discretization methods is carried out comparatively in detail.

引入一个位置控制系统作为分数阶控制对象，将Mittag-Leffler函数的全记忆长度分数阶控制系统作为评估基准，提出了一种离散算法的近似性能函数，通过时域误差分析以及近似性能分析，对比研究了分数阶微积分算子的数字实现方法。

The problem isdiscussed and the error caused by using the approximate formula proves to be superior to that caused by using the homogeneous Taylor's polynomial and an expression is proved to be similatr to the remainder in Taylor's formula.

由讨论这个问题出发，证明了用这种近似式产生的误差，优于用同阶Taylor多项式产生的误差，并给出这个误差的一个类似于Taylor公式余项的表达式。

The paper introduces the return circuit sensitivity in the experiment of the internal resistance by sensitive amperemeter with semi-bias method.

在半偏法测灵敏电流计内阻的实验中引入回路灵敏度，并采取近似处理找出回路灵敏度不足产生误差的最小值范围，同时从理论和实验两方面对回路灵敏度不足产生误差的原因进行分析，从而找到减小这一误差的途径。

The absorption and distribution of chromium were studied in ryeusing nutrient culture technique and pot experiment.

采用不同浓度K2CrO4(0，0.4，0.8和1.2 mmol/L)的Hoagland营养液处理黑麦幼苗，测定铬在黑麦体内的亚细胞分布、铬化学形态及不同部位的积累。

By analyzing theory foundation of mathematical morphology in the digital image processing, researching morphology arithmetic of the binary Image, discussing two basic forms for the least structure element: dilation and erosion.

通过分析数学形态学在图像中的理论基础，研究二值图像的形态分析算法，探讨最小结构元素的两种基本形态：膨胀和腐蚀；分析了数学形态学复杂算法的基本原理，把数学形态学的部分并行处理理念引入到家实际应用中。