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通用型旋桨流速仪性能检定方法研究 被引量:3
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作者 周冬生 宗军 +2 位作者 曹子聪 蒋东进 杨汉塘 《水文》 CSCD 北大核心 2017年第6期39-43,共5页
流速仪检定主要问题是当检定仪器数量多、水体波动大,不符合流速仪检定理论和仪表标定原则,检定成果有可能形成系统误差,它既无标准,又难发现,用均方差表示则优。分析仪器运动机理,提出:低速,用力矩仪检测起转速V_0,使用标准修订值的低... 流速仪检定主要问题是当检定仪器数量多、水体波动大,不符合流速仪检定理论和仪表标定原则,检定成果有可能形成系统误差,它既无标准,又难发现,用均方差表示则优。分析仪器运动机理,提出:低速,用力矩仪检测起转速V_0,使用标准修订值的低速直线公式;中、高速,用干式检测法,水力螺距检定法,积分检定法和优化一速度级检定法,后者还可用于水文测站验证流速仪检定公式。 展开更多
关键词 旋桨流速仪 干式 水力螺距 积分检定 优化-速度级
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Development of a Lightning Warning System
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作者 Gyung-Suk Kil Dae-Won Park +1 位作者 Kwang-Seok Jung Chang-Hwan Ahn 《Journal of Energy and Power Engineering》 2012年第2期287-292,共6页
A lightning warning system (LWS) which can predict the possibility of lightning strike and the position of lightning discharge was developed. The LWS uses the electric field intensity at the ground as a parameter to... A lightning warning system (LWS) which can predict the possibility of lightning strike and the position of lightning discharge was developed. The LWS uses the electric field intensity at the ground as a parameter to warn the possibility of lightning strikes. A planar shutter type electric field mill (EFM) with a rotating vane is studied to measure the electric field. From a calibration experiment, the sensitivity of the EFM was adjusted to 0.15 V/kV/m, and this covers the ranges from 200 V/m to 20 kV/m. Magnetic field waveform is detected by a crossed loop coil and an integral amplifier. Frequency bandwidth of the circuit ranges from 5 kHz to 1.2 MHz. The polarity of lightning discharges is discriminated by electric field component. After fixing the polarity, we can calculate the direction and distance of lightning discharge by the peak and the zero cross time of the detected magnetic field waveform. 展开更多
关键词 Lightning warning system (LWS) electric field mill (EFM) thundercloud lightning discharge electromagnetic field loop coil.
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