大电流监测信号提取的光收发及信号处理

近年来,大电流的监测成了人们十分关心的问题,这是由于大电流有强磁、高压、电流大等一系列的直接监测所不能克服的问题。这就需要把高压大电流的强电信号,经过提取后变成能在实验室中直接观测的弱电信号。为此,如何从高压大电流的信号中提取出随实时信号变化而实时变化的小信号就变成了一个关键问题。详细介绍了监测信号提取的光收发电路原理和后续信号处理电路,分析了各部分的作用,给出了必要的分析结果。     

电子电气设备的熔断器、断路器保护

熔断器、断路器是电子电气设备最常用的保护电器,熔断器可以实现过载、短路保护,断路器除具上述功能外,还能实行失压保护.根据线路特点和所保护的设备,采取相应的保护设施,确保用电安全.     

Modification to the Fringe Component of Diffraction Coefficient in TD-EEC Method

A modified formulation for fringe component of diffraction coefficient is implemented to TD-EEC method. An example of diffraction by perfectly conducting plate is used to illustrate our scheme. Comparing with the FDTD results we observe that the improved expression for fringe component is more accurate than that of Michaeli's formulation. This high frequency time domain technique is available for treating the bistatic scattering problems for millimeter waves.     

一种可调节电流的电流型PWM直流转换器

介绍一种用于驱动发光二极管(LED)的可调节电流的电流型PWM直流转换器.该直流转换器由于接有一个外接电阻,可以通过调节外接电阻的大小来调节输出电流.输出电流调节范围在5～40mA之间.主要分析了电路的输出电流调节功能,和这种输出电流可变的电流型PWM直流转换器的电流和电压反馈环的反馈实现原理.并简要介绍了这种带电流调节功能的PWM直流转换器的工作原理,最后给出了电路在输出不同电流时使用HSPICE软件对反馈参考电压,PWM锁存器输出波形的仿真结果.     

新型光电混合式电流互感器设计

设计了一种光电混合式电流互感器,它由传感头、光纤传输和光电转换器、信号处理电路和工作电源4部分组成。这种结构具有绝缘性能高、可靠性强、质量小等特点,并对误差情况进行了分析。     

静磁场中的互作用能

讨论了在激发磁场的电流保持不变时和束缚磁荷作为磁场的不变时，两种情况下磁场的相互作用能。结果与静电场类似，两种情况的互作用能中都含有相互磁化，致使物体磁化状态改变作的功。     

Possible triggering of solar activity to big earthquakes (Ms ≥ 8) in faults with near west-east strike in China

A big earthquake (Ms = 8.1) occurred at western Kunlun Mts gap on November 14, 2001. It is the biggest earthquake in China in the past 50 years and the only one with a magnitude bigger than 8 in China after Dangxiong Earthquake (M = 8) in Tibet in 1951. The big earthquake has drawn wide attention of scientists in seismological, geophysical, geological and astro-geodynamic circles. Scientists are interested in the occurrence regularity of the very big earthquakes and try to find out the fac…     

磁光玻璃光纤的偏振特性及其在全光纤电流传感器中的应用

在磁光玻璃裸光纤偏振特性研究的基础上，研制磁光玻璃光纤，偏振特性及其在全光纤电流传感器中的应用。将采用模管法拉制成的磁光玻璃光纤置于亥姆霍兹线圈产生的磁场中，当线偏振光通过该光纤时，其偏振面旋转一定角度，把该角度转换成光信号的强度，然后再用仪器进行检测。通过对线偏振光偏振面在磁场中的偏振特性的测试与实验，提出用磁光玻璃光纤构成的全光纤电流传感器，可用于电流和磁场测试。     

On the effect of a longitudinal magnetic field on oscillatory characteristics of a subnormal region in discharge in argon

Oscillating nature of current pulses under d.c. excitation in subnormal region with longitudinal magnetic field at pressure range 0.20 torr to 0.85 torr have been studied. The frequency, bandwidth, peak-peak voltage, cut-off current and rise time of the current pulses have been observed with pressure, average tube current and magnetic field. A study of these oscillograms in magnetic field, average tube current and pressure are presented. The probable mechanism for the generation of oscillation based on space-charge field modification with magnetic field is discussed     

PFC控制技术的一种改进方案

文章首先指出了目前ＰＦＣ所用控制技术的缺陷，然后提出了一各改进方案，并从理论分析和仿真验证的角度证明了改进方案的可行性和先进性。