Operation of superconducting fault current limiter using vacuum interrupter driven by electromagnetic repulsion force for commutating switch

Using conventional high‐temperature superconducting wire, a model superconducting fault current limiter (SFCL) is made and tested. Solenoid coil using Bi2223 silver sheath wire is so made that inductance is as small as possible and a vacuum interrupter is connected in series to it. A conventional reactor coil is connected in parallel. When the fault current flows in this equipment, superconducting wire is quenched and current is transferred into the parallel coil because of voltage drop of superconducting wire. This large current in parallel coil actuates magnetic repulsion mechanism of vacuum interrupter. Due to opening of vacuum interrupter, the current in superconducting wire is broken. By using this equipment, current flow time in superconducting wire can be easily minimized. On the other hand, the fault current is also easily limited by large reactance of parallel coil. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(1): 52–61, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20315     

弹力竹节牛仔布织造工艺优化

介绍了弹力竹节牛仔布的生产工艺 ,同时对KT36 8剑杆织机织造该织物的工艺进行了优化研究     

Axial vibrations of U-shaped bellows with elastically restrained end conditions

Previous work by Li et al. in the area of axial vibrations of bellows dealt with fixed end conditions. However, it is seen on several occasions that bellow ends are welded to a small pipe spool that has a lumped mass such as a valve or an instrument. Hence, the present paper aims at finding out the effect of elastically restrained ends on the axial natural frequencies. The analysis considers finite stiffness axial restraints on the bellows, i.e. solving the set of equations with non-homogeneous boundary conditions. Two bellow specimens are considered for comparison having the same dimensions as taken by Li in his analysis. The transcendental frequency equation deduced is accurate as the first, second and third mode frequencies computed are in close agreement to the ones obtained by Li.     

电镀企业火警和爆鸣事故实例

列举了作者经历的18种火警和爆呜事故，为电镀企业敲响警钟，安全重于泰山。     

蓄热式均热炉生产中存在问题的分析及解决方案

介绍了高温空气燃烧技术在均热炉上的应用情况，对应用中出现的问题进行了分析，并提出了解决方案。     

计算机高速并行通信的实现方案

利用CPLD芯片实现单片机与ISA总线接口之间的高速并行通信，给出系统的总体设计方法及程序框图。采用这种通信方式，在12MHz晶振的MCS51单片机控制的数据采集系统中，可以满足与PCI04 ISA总线接口实时通信的要求，通信速率达200khit／s。在开发工具MAX plusⅡ下，完成了整个设计的输入、编译和仿真，达到了预期效果。本设计方案能够推广应用到计算机的高速并行通信中。     

基于DSP+CPLD的高精度信号发生器

介绍了基于直接数字式频率合成(DDS)原理的全数字信号发生器(DSP),利用DSP芯片快速、高精度的运算优势以及CPLD芯片灵活的编程逻辑、大容量存储功能的特点,采用通用可编程芯片以及数字波形合成技术,形成高稳定、高精度、高动态的数字合成信号.该信号发生器可产生0～25 kHz的正弦波、三角波和方波,输出电压峰峰值为0～5 V,频率步进1 Hz,幅度步进0.001 V.     

WCDMA系统中SPT数字滤波器的一种设计方法

相对于传统的数字滤波器实现方法,符号的2次幂和(SPT)滤波器用移位寄存器替代乘法器,因而资源消耗少、速度快,更加适于专用集成电路(ASIC)设计.介绍了一种适用于宽带码分多址(WCDMA)前向信道中给定基带成形滤波器单位脉冲响应后设计SPT滤波器的方法.相对于传统的理想SPT系数优化方法,此方法更适于给定单位脉冲响应后SPT滤波器的设计,计算复杂度低;仿真结果显示,相对于更加简单的四舍五入方法,此算法在性能上又有可观的增益.     

幅频特性的数学分析

根据数控装置检测系统中传感器信号电路工作要求,以共射电压放大电路为例,分别考虑耦合电容、旁路电容、结间电容和分布电容对不同信号频率的作用,分析了电路的低频特性和高频特性,给出了上下限截止频率的解析式.由此得出,电路其他参数一定时,在低频段,下限截止频率与耦合电容、旁路电容成反比,在高频段,上限截止频率与等效输入输出电容成反比,从而为传感器系统设计提供理论依据.     

Schwingfestigkeit von Schraube‐Mutter‐Verbindungen

High cycle fatigue of bolted connections Extensive tests regarding the influences on the fatigue of bolt‐nut‐connections of preloading with torsion, of preloading with yielding, of loading with superimposed bending and of the tested lot are processed. These influences are not yet known according to VDI 2230. New testing devices were designed for these tests, which allow a far less expensive operation and may easily be used for bolts of diameters up to M100 and testing frequencies up to 1000 Hz. The validity of fatigue resistance according to VDI 2230 is specified with respect to the test results. The determined influence of the tested lots is unexpectedly high. The manufacturing process of bolts should be improved to minimize this influence.