Exposure to power frequency magnetic fields was estimated using a population - based jem which was specifically developed in the united states to assess occupational magnetic field exposure 电力频率磁场的职业暴露以美国特别针对职业族群所发展出来之工作矩阵进行评估。
2.
The railway power converter system will change the frequency of electricity produced by the e . on power plant to the lower frequency used by rail systems in central europe - from 50 hertz ( hz ) to 16 . 7 hz 该铁路电力转换系统将把e . on电厂产生的电力频率转换成在中欧铁路系统所使用的更低频率? ? 50赫兹到16 . 7赫兹。
