Retro-regression residual remediation for spectral/signal identification
First Claim
1. A method for improving regression-based spectroscopic analysis, comprising:
- a. computing a residual error between an estimated spectrum and a measured spectrum taken of a sample of a solid, liquid or gas substance to be analyzed using spectroscopy techniques, wherein the estimated spectrum is derived from mixing coefficients for members of a library spectra that are produced by computing a regression on the measured spectrum with the library spectra;
b. identifying peaks in the residual error that extend in a direction opposite to that of peaks in the measured spectrum;
c. performing a regression on the peaks in the residual error that extend in a direction opposite to that of the peaks in the measured spectrum to produce retro-regression coefficients;
d. computing corrected mixing coefficients based on the retro-regression coefficients by subtracting the retro-regression coefficients from the mixing coefficients for the estimated spectrum for a current iteration;
e. repeating (a) through (d) with the corrected mixing coefficients computed in (d) being used to generate a new estimated spectrum for computing the residual error in (a) at the next iteration; and
f. determining whether a chemical or biological constituent whose spectra is contained in said library spectra is present in said sample based on said new estimated spectrum.
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Abstract
An improved regression-based qualitative analysis algorithm useful when the mixture to be analyzed contains a compound not in the library spectra, a so-called unknown. A regression of a measured spectrum is computed against the library spectra. This regression is referred to as a “master” regression. Estimated mixing coefficients for an estimated spectrum are computed from the regression. Next, a residual error is computed between the estimated spectrum and the measured spectrum. Peaks in the residual error are identified that extend in a direction opposite to that of peaks in the measured spectrum. These peaks are referred to as “negative” peaks. A regression is performed on the peaks. This is referred to as a “retro-regression” to be distinguished from the master regression performed on the measured spectrum. Using information from the retro-regression, corrected mixing coefficients are computed and the process repeats.
23 Citations
17 Claims
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1. A method for improving regression-based spectroscopic analysis, comprising:
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a. computing a residual error between an estimated spectrum and a measured spectrum taken of a sample of a solid, liquid or gas substance to be analyzed using spectroscopy techniques, wherein the estimated spectrum is derived from mixing coefficients for members of a library spectra that are produced by computing a regression on the measured spectrum with the library spectra; b. identifying peaks in the residual error that extend in a direction opposite to that of peaks in the measured spectrum; c. performing a regression on the peaks in the residual error that extend in a direction opposite to that of the peaks in the measured spectrum to produce retro-regression coefficients; d. computing corrected mixing coefficients based on the retro-regression coefficients by subtracting the retro-regression coefficients from the mixing coefficients for the estimated spectrum for a current iteration; e. repeating (a) through (d) with the corrected mixing coefficients computed in (d) being used to generate a new estimated spectrum for computing the residual error in (a) at the next iteration; and f. determining whether a chemical or biological constituent whose spectra is contained in said library spectra is present in said sample based on said new estimated spectrum. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A processor readable medium storing instructions that, when executed by a processor, cause the processor to:
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a. compute a residual error between an estimated spectrum and a measured spectrum taken of a sample of a solid, liquid or gas substance to be analyzed using spectroscopy techniques, wherein the estimated spectrum is derived from a mixing coefficients for members of a library spectra that are produced by computing a regression on the measured spectrum with the library spectra; b. identify peaks in the residual error that extend in a direction opposite to that of peaks in the measured spectrum; c. perform a regression on the peaks in the residual error that extend in a direction opposite to that of the peaks in the measured spectrum to produce retro-regression coefficients; d. compute corrected mixing coefficients based on the retro-regression coefficients by subtracting the retro-regression coefficients from the mixing coefficients for the estimated spectrum for a current iteration; e. repeat (a) through (d) with the corrected mixing coefficients computed in (d) being used to generate a new estimated spectrum for computing the residual error in (a) at the next iteration; and f. determine whether a chemical or biological constituent whose spectra is contained in said library spectra is present in said sample based on said new estimated spectrum. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A system for spectroscopic analysis comprising:
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a. a sensor that produces data from a sample of a solid, liquid or gas substance to be analyzed using spectroscopy techniques; and b. a processor coupled to the sensor, wherein the processor is programmed to; i. generate a measured spectrum from the data produced by the sensor; ii. perform a regression of the measured spectrum with a library spectra; iii. generate estimated mixing coefficients from the regression; iv. compute a residual error between an estimated spectrum generated from the estimated mixing coefficients and the measured spectrum; v. identify peaks in the residual error that extend in a direction opposite to that of peaks in the measured spectrum; vi. perform a regression on the peaks in the residual error that extend in a direction opposite to that of the peaks in the measured spectrum to produce retro-regression coefficients; vii. compute corrected mixing coefficients based on the retro-regression coefficients by subtracting the retro-regression coefficients from the mixing coefficients for the estimated spectrum for a current iteration; viii. repeat (iv) through (vii) with the corrected mixing coefficients computed in (vii) being used to generate a new estimated spectrum for computing the residual error in (iv) at the next iteration; and ix. determine whether a chemical or biological constituent whose spectra is contained in said library spectra is present in said sample based on said new estimated spectrum. - View Dependent Claims (16, 17)
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Specification