盐关微地震群的活动局限在矿区内，地震都是微震和极微震。
The activity of microearthquake swarm is limited in an area of coal mine .
随着大功率可关断元件与微处理芯片的不断发展，大功率电力电子逆变器得到了越来越多的应用。
With the high power self-turn-off devices and intelligent high-speed microcontroller development , high power electronic converters are widely used .
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