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本文比较了ASTM标准和国标的几种计算电阻率断面不均匀度的公式.对于断面上测出相同的ρ_M、ρ_M,按国标计算的不均匀度与按ASTM计算的不均匀度在y值很小时相差无几,在y_z值在12～30%时相差1～4%.本文推导出了按各种公式计算的不均匀度的不确定度公式.在一定的置信概率下,不确定度与仪器精密度σ/ρ成正比,与不均匀度y和测量次数的平方根N~(1/2)成反比.从而提 供了为减少测量不均匀度时的不确定度,应怎样选择仪器系统的精密度和测量方法的指导原则.列出了几种不均匀度不确定度表格,供实际工作人员应用参考.
In this paper, we compare several formulas of non-uniformity of resistivity calculated by ASTM standard and national standard.For the same ρ_M, ρ_M measured on the cross-section, the non-uniformity calculated according to the national standard and the non-uniformity calculated by ASTM H, the difference between them is 1 ~ 4% when the value of y_z is between 12% and 30% .In this paper, the formula of the uncertainty of the non-uniformity calculated by various formulas is deduced. Under certain confidence probability, Precision σ / ρ is proportional to, and with the unevenness y and the square root of the number of measurements N ~ (1/2) is inversely proportional to provide an uncertainty in the measurement of non-uniformity, how to choose the precision instrument system Degrees and Methods of Measurement Guidance Several non-uniformity uncertainty tables are listed for practical reference.