A model combining spectrum standardization and dominant factor based   partial least square method for carbon analysis in coal by laser-induced   breakdown spectroscopy
  Successful quantitative measurement of carbon content in coal using laser-induced breakdown spectroscopy (LIBS) is suffered from relatively low precision and accuracy. In the present work, the spectrum standardization method was combined with the dominant factor based partial least square (PLS) method to improve the measurement accuracy of carbon content in coal by LIBS. The combination model employed the spectrum standardization method to convert the carbon line intensity into standard state for more accurately calculating the dominant carbon concentration, and then applied PLS with full spectrum information to correct the residual errors. The combination model was applied to the measurement of carbon content for 24 bituminous coal samples. The results demonstrated that the combination model could further improve the measurement accuracy compared with both our previously established spectrum standardization model and dominant factor based PLS model using spectral area normalized intensity for the dominant factor model. For example, the coefficient of determination (R2), the root-mean-square error of prediction (RMSEP), and the average relative error (ARE) for the combination model were 0.99, 1.75%, and 2.39%, respectively; while those values for the spectrum standardization method were 0.83, 2.71%, and 3.40%, respectively; and those values for the dominant factor based PLS model were 0.99, 2.66%, and 3.64%, respectively. 
Xiongwei Li, Zhe Wang, Yangting Fu, Zheng Li, Weidou Ni
physics.optics