The standard uncertainty of the input quantity is the standard uncertainty u(I). The standard uncertainty of the input quantity I is mainly derived from the standard uncertainty component u (I1 caused by the measurement non-repetition of the spring scale). ), the standard uncertainty component u(I2) caused by the reading error.
(1) Evaluation of the standard uncertainty component u(I1) caused by the non-repetition of the spring degree disc scale (Class A rating) 10 times of the 8 kg weighing point of the spring dial scale under the repeating condition with the M1 grade weight Continuous measurement, get the measurement column: (8001,8003,7995,8002,7998,8001,7995,8003,8002,7997)kgI=1n
Ni=1Ii=8000kg single experiment standard deviation S=(Ii-I)2n-1=318gu(I1)=Sn=31810=101g degrees of freedomv(I1)=n-1=9(2)spring degree disk scale Evaluation of the standard uncertainty component u(I2) caused by reading error (Class B rating) u(I2)=02e6=163gk=6 Estimate u(I2)u(I2)=020, then the degree of freedom v(I2)= 12u(I2)u(I2)2=12(3) The standard uncertainty u(I) of the input quantity I is calculated because the sub-terms of the input quantity I are independent of each other, so u(I)=u2(I1)+ U2(I2)=192g degrees of freedom v(I)=u4(I)u4(I1)v(I1)+u4(I2)v(I2)=1932The standard uncertainty u(m) of the input quantity m According to the agreement in the OIMLR111 weight international recommendation, the uncertainty of the low-accuracy level weight is equal to 1/3 of the maximum tolerance specified in the tolerance table. Check the kg specification M1 level weight maximum allowable error MPE=50mg single weight The standard uncertainty component u(m1)=50/3=0029g8 standard uncertainty component of the weight u(m)=8u(m1)=023g estimate u(m)u(m)=010, then free Degree v(m)=12u(m)2=504 Evaluation of synthetic standard uncertainty 41 Mathematical model of sensitivity coefficient: E=Im sensitive system :c1=E/I=1c2=E/m=-1 The quantization error given by the instruction manual is 1 word. When the HP8902A measures the frequency offset of 34 kHz, the resolution is 10 Hz, so a=10 Hz, assuming it obeys Uniform distribution, take kj=3, then uB2=a/3=5810-3kHz(4) Synthetic standard uncertainty can be considered as the above irrelevant, synthesized uc=u2A+2i=1u2Bi=020kHz(5) extension Uncertainty U=kuc=040 kHz (k=2, p=95%) References <1> HP8902A type measurement receiver technical specification. <2> E4421B Synthetic Signal Generator Technical Specification. <3>Technology and Quality Division of the Commission of Science, Technology and Industry for National Defense. The basis of measurement technology. Beijing: Atomic Energy Press, 2002. <4> GJB3756-99 Representation and evaluation of measurement uncertainty. <5> JJF1059-1999 Measurement uncertainty evaluation and representation.
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