通过零点

The results show that the zero speed point is located on the arc between two absolute speed zero points of rotation axes, and the necessity of relative speed zero point is demonstrated, From the location of speed zero point, some useful conclusions can be drawn.

对速度零点的位置进行了分析，得出了如下结论：对于一定形状的工件，通过调整两轴的转速比以及两轴夹角参数，可以将速度零点置于工件之外，从而避免速度零点对研磨的不利影响。

Focusing on the problems existing in the implementation of polarity crosscorrelation"zero-crossing"algorithm in the practical applications, an improved approach based on HSI (High-Speed-Input channel of MCS8098) is proposed, which makes the circuit much simpler. Experimental results indicate that higher response speed and higher accuracy rating of signal recording can be obtained with the improved approach.

针对极性相关测速"零点穿越"算法在实际实现过程中存在的"零点穿越"信号容易"漏记"，而对流速测量造成不利影响等问题，本文提出了一种基于HSI的极性相关测速的技术改进措施，硬件结构更加简单；通过实验验证，基于HSI的极性相关测速法的响应速度快，信号记录的准确率高，是一种简单有效的技术方案。

Given a planar point set,the moving least squaremethod is adopted to denoise and resample it so that the resulting point set is with low noise and uniform sampling density.Then the reliable signed distance field of the preprocessed point set is constructed by using the Level Set method.Finally,an algebraic B-spline function is adopted to fit the signed distance field by solving a linear equation system.

首先给定一个表示封闭曲线、可能带有噪音且分布不均匀的平面点云，采用移动最小平方(moving least square，简称MLS)方法对点云去噪、重采样，得到一个低噪音、分布均匀的"线状"点云，再通过Level Set方法建立该"线状"点云的离散几何距离场，最后用一个代数B-样条函数光顺拟合该离散距离场，代数函数的零点集即为重建曲线。

By making use of the property that the zero-order Bessel function's derivative J′0(0)=0, the DQDHT can calculate the values on the symmetry axis directly.

通过利用零阶贝塞尔函数导数在零点处为零的特性，所提出的准离散汉克尔变换算法可以直接计算光束传输时对称轴上的值。

This paper studies how to define corresponding pulse transfer function D′ of digital controller, while there are zeros of conjugate complex numbers or negative real number in D, poses a solution method and gives comparative analysis for three different situations.

本文对D中含有共轭复数零点，或负实数零点时，如何确定数字控制器的相应脉冲传递函数D′的问题进行了研究，提出了解决方法，通过实例对三种不同情形进行了对比分析。

Due to its good effect in the reservation of information of signal abrupt change, mathematical morphology is often applied in the detection and location of short-term power quality disturbance, however, there is still a defect of invalid detection existing in partial detection methods based on mathematical morphology while some zero-crossing disturbances are detected. In this paper three mathematical morphology based disturbance detection and location methods, i.e., the method based on first-order derivation and morphological gradient, the method based on morphological gradient and soft threshold processing and the method based on dq decomposition and top-hat transform, are analyzed, that is, by means of simulation the adaptability of these methods in the analysis on the signals of voltage sag, voltage swell and electromagnetic transient oscillation is compared.

数学形态学因其在保留信号突变点信息方面有很好的效果，因此常用于短时电能质量扰动的检测和定位，但基于数学形态学的部分方法仍存在对某些过零点扰动检测失效的缺点，文章分析了3种基于数学形态学的扰动检测和定位方法，即基于1阶求导和形态梯度的方法、基于形态梯度和软阈值处理的方法、基于dq分解和高帽变换的方法，通过仿真比较了3种方法在分析电压暂降、电压暂升、电磁暂态振荡等信号方面的适应性，结果发现基于dq分解和高帽变换的方法在检测过零点扰动时具有很好的效果，因此选取这种方法对实测扰动数据进行了检测和定位分析。

Based on two algebra Riccati equation method especially the structure of the system Hamilton matrix and system observability theory, the role of invariant zeros in constructing system reduced order controllers was given. That is, by the suitable selection of free parameters of the system H(subscript ∞) controller, some points which were symmetry with the unstable invariant zeros about the imaginary axis became the stable poles of the system controller which were not observable and could be reduced from the system, thus could get further reduced order controller.

基于2代数黎卡提方程方法，特别是系统Hamilton矩阵的结构特点和系统可观测性理论，论述了不变零点在构造系统降阶控制器中所起的作用，即通过选择控制器的自由参量，使某些不稳定的不变零点关于虚轴对称的点构成系统控制器不可观的稳定极点，从而实现了控制器进一步降阶。

In terms of hardware, bring forward the zero-crossing detection to compensate for the phase lag caused by filter.

硬件上通过提前过零检测来补偿加重滤波器带来的相位滞后；软件上加入判断过零点真伪的功能，以及先检测过零点再切换后级逆变桥的方法有效避免错误过零点造成的锁相失败问题，达到了很好的效果。

The solvability of quadratic matrix inequalities of singular H∞ control problems with infinite zeros is studied in this paper. It is proved that the quadratic matrix inequality can be solved directly via the generalized eigenvalue problems. The previous method of solving the quadratic matrix inequality involving complicated decompositions and transformations of the systems is avoided.

摘要研究具有无穷远零点的奇异H∞控制问题的二次矩阵不等式的可解性，证明了通过求解广义特征值问题，可以直接求得二次矩阵不等式的解，从而简化了原需通过复杂的系统分解和变换来求解二次矩阵不等式的方法。

An arc due to an AC signal usually quenches itself as soon as the voltage level passes through zero.

交流信号产生的电弧通常在电压通过零点时就会自己熄灭。

However, as the name（read－only memory）implies, CD disks cannot be written onorchanged in any way.

然而，正如其名字所指出的那样，CD盘不能写，也不能用任何方式改变其内容。

Galvanizes steel pallet is mainly export which suits standard packing of European Union, the North America. galvanizes steel pallet is suitable to heavy rack. Pallet surface can design plate type, corrugated and the gap form, satisfies the different requirements.

镀锌钢托盘多用于出口，替代木托盘，免薰蒸，符合欧盟、北美各国对出口货物包装材料的法令要求；喷涂钢托盘适用于重载上货架之用，托盘表面根据需要制作成平板状、波纹状及间隔形式，满足不同的使用要求。