基准矢量

Among them, the algorithm of Eigenface, the most widely-used method of linear map based on PCA, has become the mainstream criterion to test the performance of various FV systems.

目前，已经提出了许多特征提取的方法，其中基于主成分分析(PCA Principle Component Analysis)的Eigenface算法及其变形已经成为测试人脸识别系统性能的基准算法，该方法是模式识别判别分析中最常用的一种线性映射方法，是根据样本点在多维模式空间的位置分布，以样本点在空间中变化最大方向，即方差最大的方向，作为判别矢量来实现数据的特征提取与数据压缩的。

On the basis, with model reference adaptive method, the rotating speed estimation for vector control system with no-peed sensor is studied. In addition, aiming at the problem that the reference model is easily influenced by the initial value and drift of integral in normal speed recognizer, the traditional MRAS is improved, and modeling simulation is also conducted.

在此基础上，应用模型参考自适应方法，对无速度传感器矢量控制系统的转速估计进行研究，并针对常规速度辨识器中的基准模型易受积分初值和漂移影响的问题，对传统的MRAS方法进行改进，并对其进行建模仿真。

In order to establish high precision laser scanning plane, the laser beam transmission is anatomized in the formation of the scanning plane.

为了建立高精度的激光扫描基准平面，对扫描平面形成过程中光束的传播进行了详细分析；根据光学矢量反射定律，推导出了扫描误差的理论公式；在此基础上揭示了误差补偿的基本原理，导出了用于补偿扫描机构产生的扫描误差的理论公式；提出了据此准则进行设计的扫描机构的模型。

The article presents the developing condition of PWM and SVPWM first.Then the theory of SVPWM is discussed in detail.The SVPWM is based on the thought of magnetic chain tracking.It makes the ideal magnetic chain circle of three-phased sysmmetry electric motor supplied by three-phased sysmmetry sine wave voltage for basis,uses the practical magnetic chain vector formed by the different switch modes of three-phased inverter to track the basic magnetic chain circle.During the course of tracking,the inverter changes the switch modes properly to form the PWM waves.Then the modulation wave of SVPWM is analyzed in detail.The modulation wave of SVPWM is implicit,but the analogous modulation wave in A-B-C axis needs to be calculated in order to expose the internal relation of SVPWM and SPWM.That is to show the implicit modulation wave of SVPWM. SVPWM actually is a transformed SPWM ruly sampled by the modulation wave which is injected by the zero prefaces based on space vectors.

本文首先对脉宽调制技术的发展现状进行了综述，在此基础上分析了电压空间矢量脉宽调制技术的发展现状；接着对空间电压矢量脉宽调制技术的基本原理进行了详细的分析和推导，SVPWM是基于磁链追踪的思想，它以三相对称正弦波电压供电下三相对称电动机定子理想磁链圆为基准，由三相逆变器不同开关模式下所形成的实际磁链矢量来追踪基准磁链圆的，在追踪的过程中，逆变器的开关模式作适当的切换，从而形成PWM波；然后详细分析了电压空间矢量脉宽调制技术的调制波，虽然SVPWM法的调制波是隐含的，但是为了揭示SVPWM法与SPWM法的内在联系，需要求出SVPWM在A-B-C坐标系上的等效调制波，也就是将SVPWM的隐含调制波显化；SVPWM实质是一种基于空间矢量在三相正弦波中注入了零序分量的调制波进行规则采样的一种变形SPWM。

We have no common name for a mime of Sophron or Xenarchus and a Socratic Conversation; and we should still be without one even if the imitation in the two instances were in trimeters or elegiacs or some other kind of verse--though it is the way with people to tack on 'poet' to the name of a metre, and talk of elegiac-poets and epic-poets, thinking that they call them poets not by reason of the imitative nature of their work, but indiscriminately by reason of the metre they write in.

索夫农 、森那库斯和苏格拉底式的对话采用的模仿没有一个公共的名称；三音步诗、挽歌体或其他类型的诗的模仿也没有——人们把&诗人&这一名词和格律名称结合到一起，称之为挽歌体诗人或者史诗诗人，他们被称为诗人，似乎只是因为遵守格律写作，而非他们作品的模仿本质。

The relationship between communicative competence and grammar teaching should be that of the ends and the means.

交际能力和语法的关系应该是目标与途径的关系。