To measure the performance of high precision air-pressure sensors in below normal pressure,an automatic measurement instrument has been designed and implemented.It can simulate environment of low pressure from 300hPa to 1 000hPa with high accuracy by proportional-integral-derivative（PID）control quickly,and it can also generate various relative humidity by two-pressure control.The results show that this instrument can reach controlled pressure quickly.And it works well with the minimum average pressure difference,and the fluctuation is±0.02hPa at 500hPa.And it can keep in a stable status for a long time.It works well in performance testing of pressure sensors.The structure of the system is simple,takes small investment,and can be operated conveniently.
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机译：Design and calibration of a three-dimensional localization system for automatic measurement of long and thin tube based on camera and laser displacement sensor
机译：Li et al. Comment on “Retrieval of Atmospheric Fine Particulate Density Based on Merging Particle Size Distribution Measurements： Multi-instrument Observation and Quality Control at Shooxian ”by Li et al.
机译：Reply to Comment by Peng and Bi on "Retrieval of Atmospheric Fine Particulate Density Based on Merging Particle Size Distribution Measurements: Multi-instrument Observation and Quality Control at Shouxian"
机译：Consciênciametatextual：evidênciasdevalidade para instrumento de medida Consciencia metatextual：evidencias de validez para instrumento de medida metatextual awareness：measurement of instrument of measuring instrument
