charcoal gray是什么意思

用法例句

The structure,principle,calibration method,and affecting factors in detection of a portable analyser for ash content in coal based on low-energy γ-ray method have been presented.

该法在煤炭灰分的测量精度方面虽不及试验室的常规测定,但测量周期很短,仅为30s,加之该仪器重量轻,可任意移动,将有较好的应用前景。