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The basic principles and evolution process of Active Power Filter are first introduced. The scheme and structure of single-phase hybrid filter system is then illustrated and quantitative analysis is made based on the harmonic and reactive compensation principles. Through theoretical derivation, the said system has been proved to have the function of harmonic and reactive compensation.

本文首先介绍了有源电力滤波器(Active Power Filter，简称APF)的基本原理及发展历程，阐述了单相混合型滤波系统的方案和结构原理，对其进行了谐波和无功补偿原理的定量分析，通过理论推导证明了该系统具有谐波和无功补偿的功能。

Starting from the Laplace equation, the solution of Laplace equation, in spherical coor dinates, is developed for the boundary value problem approximating the local gravity field over a spherical cap——spherical cap harmonic analysis, and the spherical cap harmonic expansion with integral order but nonintegral degree and practical formulae are given.

从Laplace方程出发，提出了在球冠上逼近局部重力场的大地测量边值问题——球冠谐分析理论，给出了非整阶整次球冠谐展开和实用计算公式。

In Chapter 6, by using the matrix models of 3-dimensional Minkowski space R〓, first we study deformation properties and integrablilities on spacelike surfaces with a harmonic inverse mean curvature and timelike surfaces with a Lorentz harmonic inverse mean curvature.

在第六章中，首先借助三维Minkowski空间R〓的矩阵模型，研究了R〓中具有调和逆平均曲率的类空曲面和洛伦兹调和逆平均曲率类时曲面的可积性及其形变。

Results indicate that:(1) by using HANTS, the researchers could get the EVI/NDVI harmonic curves, the mean VIs and the amplitude of the harmonics which then were utilized in the identification of the cultivated land, and EVI appeared to be more precise, with the overall accuracies of 97.17% and 95.99% and Kappa coefficients of 0.7938 and 0.6518, respectively.(2) Multiple cropping index was extracted by counting the number of the curve's peak; and when the threshold of the peak value of the NDVI and EVI curves were set as 0.25 and 0.20, respectively, the fallow land could be well figured out.(3) From harmonic curves, some eigenvalues, such as time of the maximum growth rate, time of peak and the value of peak can be extracted, based on which the crop types can be primarily distinguished. And EVI still performed better than NDVI in this section.

结果显示：（1）利用傅立叶谐波变换得到的EVI和NDVI时间谱曲线的谐波余项及谐波振幅对耕地进行识别，从识别精度来看，EVI要优于NDVI，识别精度分别为97.17%和 95.99%，Kappa系数分别达到0.7938和0.6518；（2）通过计算时间序列曲线的波峰数能够提取耕地的复种指数，并且在EVI和NDVI曲线波峰阈值分别设为0.20和0.25时，休耕地能较为准确地被识别出来；（3）通过提取作物生长期内曲线的VI最大增长速率时间点以及峰值时间点等信息，作物种类能被初步识别，并且EVI较NDVI具有更强的识别能力。

Detect and measure harmonic is needed to control harmonic.

要抑制谐波，必须对谐波进行检测和测量。

Harmonic measure method is the key of the measurement. In this paper, the harmonic measure method which based on the multiple frequency rotate transform theory is researched and analyzed.

谐波测量方法是谐波测量的核心环节，本文对基于倍频旋转变换理论的谐波测量方法进行了研究分析。

Keywords: Harmonics, active power filter, Fourier Algorithm, Harmonic analysis and measure, Harmonic prevention

谐波，有源滤波器滤波器，傅立叶变换，谐波分析测量，谐波抑制

Traditional instrument in harmonic measurement is the transformer with circularity form core coil, but it is influenced by direct current and saturated, so it could not be used to measure direct harmonic current.

基于Rogowski 线圈的光电直流谐波电流测量系统解决了传统谐波电流测量受直流分量影响的难题，是集光纤技术、电子技术、激光技术于一体的新型谐波电流互感器。

Because the harmonic is harmful to the electric net and electrical equipment, it is very important to measure the harmonic accurately and restrain it. Some methods for harmonics measurement are proposed in these years.

由于谐波对电网及用电设备有诸多危害，准确测量谐波及抑制谐波就显得尤为重要。

Use the Rogowski coil as the sensor and transmit the signal and energy with the optic fibre, analyse the principle of the measurement of harmonic current in HVDC system and the factors of its measurement of influence by opticelectricity and computer technology. The Rogowski coil is used to measure the harmonic current in HVDC system. It doesnot affect by direct current and has good frequency characteristics.

本文在全面分析高压直流谐波电流测量方法的基础上，确定以空心线圈为传感器，以光纤传输信号和能量，结合光电技术、微计算机技术，系统地分析了谐波电流测量系统的工作原理及影响其测量的多种因素，提出了解决问题的具体方法和措施。

As she looked at Warrington's manly face, and dark, melancholy eyes, she had settled in her mind that he must have been the victim of an unhappy attachment.

每逢看到沃林顿那刚毅的脸，那乌黑、忧郁的眼睛，她便会相信，他一定作过不幸的爱情的受害者。

Maybe they'll disappear into a pothole.

也许他们将在壶穴里消失