A BOUNDARY INTEGRAL EQUATION AND ITS NUMERICAL SOLUTION OF POTENTIAL FLOW AROUND SURFACE-IRREGULA-RITIES

In this paper,using complex functional theory,the authors turn the potentialflow around the surface irregularities in a pressure conduit and semi-infinite platforms intoDirichlet problem.Based on Schwarz formula and by the application of Plemelj's formula,theauthors change the problem into the integration of a Cauchy boundary integral equation in theflow plane through the substitution of variables.Using numerical integration,the authors obtainthe velocity distribution and pressure coefficient along surface irregularities and platforms.Thephysical concept of this method is clear,the convergent speed is rapid and the computative effi-ciency is high.The calculated values agree well with the measured results.It is an effective andsimple method in solving potential flow.     

RH-KTB耐材长寿技术研究及应用

介绍了宝钢RH-KTB工艺条件下RH用镁铬砖的应用和提高浸渍管管龄、下部槽槽龄的方法.     

Optical phase conjugation of multiwavelength signals in adispersion-shifted fiber

Optical phase conjugation (OPC) of multiwavelength signals in a dispersion-shifted fiber (DSF), which can be used for dispersion compensation in the wavelength division multiplexing communication system, is theoretically studied. The multiwavelength phase-conjugate signals are generated by four-wave mixing (FWM) in the dispersion-shifted fiber. There are the pulse-shape distortion and the induced frequency chirping in the phase-conjugate signals owing to pump depletion and the cross-phase modulation among the signals and phase-conjugate signals, respectively. The FWM among the pump wave, signals, and phase-conjugate signals causes unequal conversion efficiencies for the multiwavelength signals and enhances the induced frequency chirping in the phase-conjugate signals. The induced frequency chirping may deteriorate the restoration of the pulse shape. Both the pulse-shape distortion and induced frequency chirping increase with the signal and pump powers. The formula for the induced frequency chirping that is only caused by the signals through cross-phase modulation is derived. The requirement of the signal power in the dispersion-shifted fiber for the restoration of the pulse shape by the optical phase conjugation is estimated and numerically verified     

MMDS技术综述

本文介绍多点多频道电视信号开路分配服务系统,并简述了传输接收技术。     

DX型数据采集与无线传输系统

DX型数据采集与无线传输系统能对油井压力、温度、载荷和流量等参数进行自动采集 ,并通过无线传输向总站提供实时参数 ,为及时决策提供信息。数据采集系统采用STD总线 ,测量精度高、故障低 ;无线传输系统采用短波电台和具有自动纠错功能的数传机 ,抗噪能力强、可靠性高。文章介绍了DX型数据采集与无线传输系统的组成、工作原理、功能和主要技术指标     

信钢炼钢厂转炉氧枪改造实践

对信钢炼钢厂25t转炉氧枪及喷头存在的缺陷进行分析,结合生产实践,提出了相应的改进措施,提高了冶炼速度,加快炼钢节奏,取得了良好的效果.     

利用5A284型铣齿机加工转盘螺旋锥齿轮探讨

利用引进设备5A284苏联铣齿机加工石油钻机转盘螺旋锥齿轮，建立计算程序并进行调整计算，详述了遇到的问题及解决方法，使所加工的锥齿轮质量良好。     

TEM study of PLZT ceramics

The microscopic structures of PLZT(7.9/70/30 and x/65/35, x = 7 or 8) ceramics were studied by means of transmission electron microscopy. The presence of micro-regions in PLZTs was first verfied.     

三峡工程明渠提前截流方案及水力学试验研究

论述了三期明渠提前截流方案的综合比较分析及截流水力学试验研究成果。认为拟定的提前截流诸方案各有利弊 ,其截流难度较初设方案显著增加。对于截流“基本方案”及“比较方案”的成功实施 ,必须辅之以一定的工程技术措施降低截流难度     

手机市场呼唤召回制度

我国移动电话用户数已跃居世界第一位,且依然蕴藏着巨大的商机。由此不但引发了日趋激烈的市场竞争,而且造成了产品质量投诉量的居高不下,其中对于存在先天设计缺陷产品的处理目前在我国尚无法可依。国际上对缺陷产品实行的召回制度同样适用于我国。这是市场经济规则的需要,也是商家诚信作风的体现。我国已融入世界经济大潮之中,目前建立手机召回制度是必要和适时的。对生产企业而言,一旦发现缺陷产品流入市场,即刻确认并将其召回是明智之举。