BOREAL LASER GasFinder FC, Руководство по эксплуатации

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9.5
Boreal Laser Inc. GasFinderFCr Operation Manual — Appendices July 17th 2017
Appendix D — Explanation of R 2
When the GasFinderFCr receives the returning laser signal after it has passed through the
sample gas, the receiver converts it to the shape of a specifi c waveform or curve. This is the
sample waveform. The
GasFinderFCr also receives a similar signal after the laser beam has
passed through the internal reference cell. These curves are then digitised and compared as
two numeric arrays.
An accepted mathematical procedure to compare curves or numeric arrays is the Linear
Least Squares Regression analysis. This analysis results in a measure of the similarity
( R
2
), between the waveform of the sample gas and that of the reference cell gas. A perfect
similarity would give a value for R
2
of 1.0, and a total mismatch would be 0.0.
The dark line represents the Linear Least Squares fi t of the data and is the best fi t of a straight
line between the reference (X) and sample (Y) data points. The slope is a component in the
ratio-metric calculation of gas concentration.
Regression Analysis for
Waveform B
R2 = 0.04
Sample Waveform B
R2 = 0.04
Sample Waveform A
R2 = 0.98
Regression Analysis for
Waveform A
R2 = 0.98