查询词典 impedance

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。

Impedance Cardiography is an important clinical means of detecting and diagnosing cardiovascular diseases.

中文摘要：胸阻抗血流图(Impedance Cardiography，ICG)是临床医学中检测和诊断心血管疾病的一种重要手段。

In this dissertation, the author discusses the numerical solution for the direct acoustic scattering problem with the Neumann boundary condition, and pays more attentions to discuss numerical recovering the shape of the obstacle region, which is the inverse problem of the direct acoustic scattering problem with the Dirichlet or impedance boundary condition.

本文重点研究了Neumann边界条价下的声波障碍散射正问题和Dirichlet、Impedance边界条件下的声波障碍散射区域反问题的数值计算方法，得到很好的理论结果和数值结果。

Objective To develop a new Two-step magnetic resonance electrical impedance tomography algorithm based on radial basic function neural network for imaging electrical impedance distribution of a head.

目的基于径向基函数（radial basic function，RBF）神经网络的两步核磁共振电阻抗成像（magnetic resonance electrical impedance tomography，MREIT）算法，对人体头部进行MREIT。

YAN Dandan,ZHANG Xiaotong,ZHU Shanan,Bin HeAbstract: Objective To develop a new Twostep magnetic resonance electrical impedance tomography algorithm based on radial basic function neural network for imaging electrical impedance distribution of a head.

目的 基于径向基函数(radial basic function，RBF)神经网络的两步核磁共振电阻抗成像(magnetic resonance electrical impedance tomography，MREIT)算法，对人体头部进行MREIT。

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。

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。

7 ENERGY LIMITING CIRCUIT/ENERGY LIMITING IMPEDANCE - A circuit or component depended on to limit an output to Class 2 levels or to limit energy to an accessible part .

2.7 ENERGY LIMITING CIRCUIT/ENERGY LIMITING IMPEDANCE(能量限制电路/能量限制电阻)——根据对二类级别输出的限制或对可接触能量的限制所决定的一个电路和元件。

If the fault is out of the line, the calculation value of fault component integrated impedance reflects the line capacitive impedance with a greater amplitude; if the fault is on the line, it reflects the system impedance and line impedance with a relatively smaller amplitude. According to the amplitude of the fault component integrated impedance, the fault location can be distinguished.

在外部故障时，该比值反映输电线路上的容抗，其模值较大，内部故障时，该比值反映系统电源阻抗和线路阻抗，其模值相对较小，据此可以区分线路上的内部和外部故障。

If the fault is out of the line, the calculation value of fault component integrated impedance reflects the line capacitive impedance with a greater amplitude; if the fault is on the lines it reflects the system impedance and line impedance with a relatively smaller amplitude. According to the amplitude of the fault component integrated impedance, the fault location can be distinguished.

在外部故障时，该比值反映输电线路上的容抗，其模值较大，内部故障时，该比值反映系统电源阻抗和线路阻抗，其模值相对较小，据此可以区分线路上的内部和外部故障。

Neither the killing of Mr Zarqawi nor any breakthrough on the political front will stop the insurgency and the fratricidal murders in their tracks.

在对危险的南部地区访问时，他斥责什叶派民兵领导人对中央集权的挑衅行为。

In fact,I've got him on the satellite mobile right now.

实际上 我们已接通卫星可视电话了