EXTREMELY LOW FREQUENCY MAGNETIC FIELD SUSCEPTIBILITY OF VISUAL DISPLAY UNITS

Extremely low frequency (ELF) magnetic field susceptibility is an index of visual display unit (VDU) quality and performance. This paper provided field measured data on the susceptibility for a large variety of VDUs. A test rig was built to study the susceptibility of VDUs to magnetic fields at fundamental and third harmonic frequencies. It was found that the susceptibility level is largely dependent on refresh rate of the VDU and the orientation of the external ELF field. It was also found that the VDU susceptibility is significantly increased in the presence of harmonic frequency magnetic fields. About 30% of the tested samples have susceptibility levels higher than that stated in IEC 1000-4-8 standard.

视频显示器的极低频磁场敏感度和辐射测量

视频显示器（VDU）易受极低频（ELF）磁场干扰，但其本身也向周围辐射电场和磁场。VDU的ELF磁场敏感度和辐射程度已经成为衡量其质量和性能的指标之一。给出了5个厂家9种型号共36台VDU的敏感度和辐射测量结果。设计制作了用于测量工频和3次谐波磁场敏感度的实验装置。发现VDU对ELF磁场的敏感度与其刷新频率和外部磁场的方向密切相关。与工频磁场相比，VDU对谐波磁场的敏感度更高。对照有关电磁兼容国际标准对敏感度和辐射测量结果进行了分析。

北京平原区中更新世晚期以来古环境演变——以平谷Zk09钻孔为例

对位于北京平谷马坊村新生代Zk09孔沉积物磁化率、色度现场测试和碳十四、光释光年龄测试表明,北京平原区东北部65m深地层沉积稳定,沉积时代约为250ka以来。期间沉积地层磁化率、色度同岩性关系密切,主要受控于氧化-还原环境条件和水动力条件,即温度和降水古气候环境,可作为重要的古气候演化替代性指标。其沉积物地层年代-磁化率、色度曲线发育7次演化旋回,较好记录了MIS1—MIS7倒数第二次冰期间冰期以来的古气候环境演化过程。

基于LabVIEW和GPIB总线的磁场辐射敏感度自动测试系统

本文介绍了用LabVIEW开发的基于GPIB总线的磁场辐射敏感度自动测试系统,它满足电磁兼容国家军用标准GJB151A/GJB152A的要求。文中详述了磁场辐射敏感度(RS101)项目自动测试系统的组成、测试原理,软件结构以及解决的难点和关键技术。与普通的台式仪器、手动测试相比,该系统提高了测试速度,并具有良好的扩展性。