| WAVELENGTH SELECTION IN MULTICOMPONENT NEAR-INFRARED CALIBRATION |
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| 作者姓名： | PHILIP J.BROWN |
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| 作者单位： | Department of |
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| 摘 要： | Modern scanning(near-)infrared reflectance/absorption(NIR)spectroscopes measure the absorptions orreflectances at a sequence of around 1000 wavelengths.Training data may consist of 10-100 carefullydesigned sample mixtures for which the true composition of the mixture is either known by formulationor accurately determined by wet chemistry.In future one wishes to predict the true composition fromthe spectrum.In this paper we compare a simple wavelength selection approach with methods whichretain all the wavelengths.It offers a powerful yet simple technique for choosing those wavelengths thatare specific to each pure component as against the other components(including the medium)for thevarying compositions.In the presence of a defined range of ingredients it thus chooses wavelengths whichare highly selective for each particular component.It has the added advantage of selecting wavelengthswhich are little effected by interaction effects and consequent non-linearities.The calibration data used consist of 125 observations of three sugars,each varying at five levels in afull 5~3 design.The validation set consists of 21 further samples specially selected to have compositionsoutside the range of the training sample.The selection methods perform much better on this predictionset than methods which retain all the wavelengths,700 in this case.The leave-one-out cross-validationinternal to the calibration data would point to the opposite finding and suggests that such cross-validations may be overly flattering to techniques such as partial least squares and may encourageoverfitting.After selection,simple straightforward least squares methods may be used,eschewing theneed for‘shrinkage’methods such as partial least squares or ridge regression.
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WAVELENGTH SELECTION IN MULTICOMPONENT NEAR-INFRARED CALIBRATION |
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| PHILIP J.BROWN.WAVELENGTH SELECTION IN MULTICOMPONENT NEAR-INFRARED CALIBRATION[J].Journal of Geographical Sciences,1992(3). |
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| Authors: | PHILIP JBROWN |
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| Institution: | PHILIP J.BROWN Department of Statistics and Computational Mathematics,University of Liverpool,PO Box,Liverpool L BX,U.K. |
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| Abstract: | |
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| Keywords: | NIR spectroscopy Wavelength selection Interaction effects Multicomponent mixtures Partial least squares Generalized least squares |
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