They are caused by the counter - rotating waves set up in the earth's electric field.
他们是导致在地球电场上形成逆向旋转波动的原因.
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On - line monitoring and trouble diagnosis system of counter - rotating type of axial fan for mine is introduced.
介绍了矿用对旋轴流式主通风机的在线监测和故障诊断系统.
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Equipped with reversible mechani sm to avoid the reel counter - rotating to leade the springs broken.
设置了可逆转机构,避免卷筒逆转而折断弹簧.
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