Different-years Model Transfer Of Near-infrared Spectroscopic Analysis Of Sugarcane Syrup

Cane sugar manufacturing is an important pillar industry in southern China.Clear syrup is an intermediate product in sugar production of sugarcane,and Brix is an important quality index in sugar production process analysis.Traditional measurement methods need to be sampled,diluted,and laboratory manual means such as hammer meter(or refractometer).The operation is tedious and time-consuming,which has little guiding effect on real-time production.Near infrared spectroscopy has the advantages of fast,simple and reagent-free,and has been applied to the rapid(or on-line)detection of intermediate products in sugarcane sugar production.Near infrared spectroscopy is an indirect analytical technique that requires the establishment of a calibration model from the spectra and physicochemical values of known samples to predict unknown samples.The parameter stability of the model directly affects the prediction effect of the sample.Sugarcane is an annual crop.Due to the dynamic changes of samples,instruments and measurements,NIR analysis of different years requires model transfer(dynamic maintenance),which is an important topic for urgent research.In this paper,the near infrared spectroscopy analysis of Brix in sugar cane syrup was used to study the model transfer method for three years(2006-2008).Firstly,the Norris derivative filtering(NDF)method for spectral preprocessing was studied.Based on partial least squares(PLS)regression,a Norris parameter optimization platform for the number of derivative order(d),smooth points(s)and differential interval(g)cycles was constructed.The optimal Norris parameters of PLS model for each year were determined,and the NDF joint parameter method for three-year model transfer was further proposed.Secondly,the moving window PLS(MW-PLS)method for feature wavelength selection was studied.The MW-PLS parameter optimization platform of initial wavelength(I),number of wavelengths(N)and the latent variables(LV)of PLS was constructed.The optimum parameters of MW-PLS model for each year were determined,and the MW-PLS joint waveband method for three-year model transfer was proposed.Slope/Bias(S/B)method was used to realize the model transfer of near infrared spectroscopy analysis of Brix in sugar cane syrup in 2006-2008 years.The main results are as follows:(1)Independent modeling of samples for the same year: 1)Norris-PLS model of samples in 06,07 and 08 years.The optimal Norris-PLS model parameters for the three groups were d=2,s=33,g=10;d=2,s=13,g=5;d=2,s=9,g=6,respectively.The deviation(RMSEP)between the predicted and the measured values of the Brix in syrup are 0.79,1.17 and 0.87(%),respectively.The correlation coefficient(RP) between the predicted and the measured values are 0.982,0.907 and 0.937,respectively.The relative errors(R-RMSEP)are 1.2,1.8 and 1.4(%),respectively.Compared with the direct PLS model without spectral pretreatment,the RMSEP decreased by 16.8,5.6,and 5.4(%),respectively.2)MW-PLS model of samples in 06,07,and 08 years.Based on the Norris spectrum,the MW-PLS model was optimized.The optimal MW-PLS model parameters for the three groups samples are I=1940,N=62,LV=8;I=1994,N=56,LV=7;I=478,N=213,LV=7,corresponding wavebands are 1940-2068,1940-2104,and 478-902(nm),respectively.The RMSEP values are 0.67,1.10,and 0.61(%),respectively,and the RP were 0.988,0.920,and 0.957,respectively.R-RMSEP is 1.0,1.7 and 1.0(%),respectively.Compared with the above Norris-PLS model,the RMSEP decreased by 15.2,6.0,and 29.9(%),respectively.(2)Model transfer for the three-year samples: 1)NDF joint parameter method.Based on the cluster analysis of all Norris-PLS models in each year,the NDF joint parameters for three-year model transmission are determined as d=2,s=9,g=6.On this basis of the Norris-PLS and S/B methods,six models transfer between any two years were established.The results show that there are five cases,the transfer effects of the Norris-PLS joint model were better than that of the direct PLS model without pretreatment.2)MW-PLS joint waveband method.Based on the cluster analysis of all MW-PLS models in each year,the MW-PLS joint waveband that can be used for the triennial model transfer is determined to be 884-904 nm.On this basis of MW-PLS and S/B methods,six model transfers between any two years are established.The results show that in all six cases,the transmission effect of the joint waveband MW-PLS model were better than that of the previous direct PLS model and Norris-PLS model.In this paper,the NDF joint parameter method for the three-year model transfer of sugarcane syrup was analyzed,and the MW-PLS joint waveband method was further proposed.Through the integration optimization,the transfer of the six models in any two years has achieved significant improvement.These methods proposed in this paper provides a new idea and valuable reference for solving the dynamic maintenance(model transfer)of near-infrared application model and special instrument design,which is of great significance to the quality analysis of sugarcane sugar production process in China.