阻抗

Based on varying process of generator terminal parameters after excitation fault, shortages of excitation protective principle of static stability boundary and asynchronous impedance boundary are analyzed. It proposed that excitation fault research relates to large-disturbance stability. Because dynamic power-angle character of generator after excitation fault is non-sinusoidal, there are differences between dynamic power-angle character and static state power-angle character. So it isn't ideal to protective operation result based on small-disturbance stability and static stability boundary criterion. At the same time, it proposed that asynchronous boundary impedance criterion is a constant reactive power circle moving adown j Xd′. It can ensure complete loss-of-excitation generator measuring impedance enter into the circle, but can't ensure the other condition measuring impedance including impossible losing synchronism enter. So loss-of-excitation protection would be maloperation when system voltage drops short and recovers or generator rejects load.③Based on stability principle, it puts forward setting conditions and calculation method of generator loss-of-excitation protection by direct measuring power-angle.

以励磁故障后发电机端的相关参数的变化为基础，通过对以静稳定边界和异步阻抗边界作判据的两类三种现行励磁保护在原理上存在的缺陷分析，发现：励磁故障是一个大干扰稳定性问题，励磁故障后的发电机的动态功角特性与静态功角特性有很大的差异，已远非正弦曲线，因此基于小干扰稳定性原理、以静稳定边界作判据的保护必然动作不理想；异步边界阻抗判据是一个下移j Xd′的等无功阻抗圆，它可以保证完全失磁后的发电机测量阻抗能进入该阻抗圆，但不能保证完全失磁之外的其它状态不会进入该阻抗圆，因此在系统电压短时下降或发电机突然甩负荷等情况下可能启动该保护使之误动。

From the lumped equivalent circuit model, the phase shift/attenuation and impedance characteristics of the novel structure are first analysed based on the Bloch theory, which shows the novel structure has properties analogous to those of a bandpass filter: the attenuation constant keeps zero with a continuous and smooth characteristic impedance distribution within the passband and the bandwidth may be arbitrarily specified; characteristic impedance is purely imaginary with the inhibition of the electromagetic wave propagation outside the passband.

首先从一般的等效电路模型出发，根据Bloch周期性理论对该结构的相移、衰减和阻抗特性进行了分析，结果表明该新结构具有类似带通滤波器的特性：通带内衰减常数为零，特性阻抗为实数并随频率连续平滑分布，具有可任意指定的阻抗匹配带宽；带外特性阻抗为纯虚数，电磁波传播受到抑制。

The result indicates that hydraulic resistance coefficient is not constant;it changes with the flow ratio of diffluent and conflux.

在各流态下3种阻抗孔的阻抗系数与分流比的二次曲线图几乎重合在一起，这说明了阻抗孔口的形式对相应阻抗系数大小的影响不大。

Methods: With the help of CF type peripartal detective and diagnostic instrument, ventricular ejective resistance,arterial specificity resistance,arterial terminal resistance and total peripheral resistance were observed to investigate the changes of peripheral resistance;capillary flow velocity and circulatory continuity ratio were monitored to study the changes of microcirculatio...

运用CF型围产监测仪检测左室射血阻抗、动脉特性阻抗、动脉终端阻抗及总外周阻抗，以研究外周阻力变化；检测毛细血管血流速度及微循环灌注连续性比率，探讨微循环改变；同时探讨血容量与血粘度变化。

The impedance ratio and the meander could control the frequency of the second harmonic and the baseband ratio. According to that,we analyze several kinds of stepped impeedance resonator and use them to design the dual-band bandpass filters.In the thsis , The proposed bandpass filters and dual-band bandpass filters are designed for IEEE 802.11a/b wireless communicatuon system.

双频带带通滤波器是利用步阶阻抗谐振器之阻抗比与传输线之折线，可用来控制第二次谐波的频率与基频通带的比值，藉由改变阻抗比，来求得所要的第二次谐波，利用此特性，其中分析了几种不同形式的步阶阻抗谐振器，皆可用来设计双频带带通滤波器，带通滤波器与双频带带通滤波器是针对IEEE80211a与IEEE802.11b无线区域网路所设计。

aining at high impedance weak signal measurement,the relations among measuring precision,input impedance and input bias current,the guard technology is applied to design a measuring circuit with guard circuit,adding a guard potential to low-impedance nodes of circuit,the effect of leakage current is reduced.using spice simulation and validates that guard circuit can increase the input impedance of the system and lower the input bias current,the results show that the guard circuit provids a valuable solution for high accuracy measurement of the high impedance weak signal.

摘 要：针对高阻抗微弱信号测量问题，对测量精度与系统输入阻抗、输入偏置电流的关系进行分析，应用保护技术设计了带保护电路的测量电路，将电路中的低阻抗节点加上保护电势，减小漏电流的影响。通过pspice仿真分析，验证保护电路能提高测量系统的输入阻抗和降低输入偏置电流，结果表明保护电路技术能实现对高阻抗微弱信号的高精度测量。

It usually takes a long time to fill the impedance matrix when using higher-order MoM. To solve this problem, the properties of the impedance matrix elements and the involved integral are investigated. Then it is proposed to take advantage of the symmetry of impedance matrix and the integral table to expedite the impedance matrix filling.

针对高阶矩量法阻抗矩阵填充时间很长的问题，从阻抗矩阵元素本身的性质和积分计算过程入手，提出了应用阻抗矩阵对称性和积分表方法两种加快阻抗矩阵填充的手段。

Recently, the internal research on the traffic network flow equilibrium problem has mainly used the current abroad applications to compute the link impedance,which are available with the actual situation of the urban road network.

二、目本文首先明确了路阻的定义，并将道路阻抗分为行程道路阻抗和交叉口阻抗两部分，借鉴电路网络中非线性电阻联结理论，介绍了求解道路的复合阻抗方法，并加以证明。

The high impedance line part is disposed between the first low impedance line and the second low impedance line, and the input end and output terminal are asymmetrically arranged both sides of a syntonizer composed of the high impedance line, the first low impedance line as well as the second low impedance line.

高阻抗线部分设置于第一低阻抗线与第二低阻抗线之间，且输入端与输出端非对称设置于高阻抗线与第一低阻抗线以及第二低阻抗线所组成的谐振器的两边。

The system comprises first and second antennas for receiving first and second RF signals of first and second frequencies, respectively; a mobile switch for measuring performance characteristics of the second antenna; and a switch circuit connected between the second antenna and the mobile switch for controlling flow of the first RF signal to the second antenna.

在移动通信终端内，一开关电路，用于根据工作模式控制CDMA天线的输入阻抗，该开关电路被连接在CDMA天线和移动开关之间，以便在GPS工作模式下维持CDMA天线的输入阻抗为高阻抗，来切断GPS信号的流入，以及在CDMA工作模式下维持CDMA天线的输入阻抗为低阻抗以接收CDMA信号。

They weren't aggressive, but I yelled and threw a rock in their direction to get them off the trail and away from me, just in case.

他们没有侵略性，但我大喊，并在他们的方向扔石头让他们过的线索，远离我，以防万一。

In slot 2 in your bag put wrapping paper, quantity does not matter in this case.

在你的书包里槽2把包装纸、数量无关紧要。