We applied near-infrared(NIR)spectroscopy with chemometrics for the rapid and reagent-fee analysis of serum urea nitrogen(SUN).The modeling is based on the average effect of multiple sample partitions to achieve param...We applied near-infrared(NIR)spectroscopy with chemometrics for the rapid and reagent-fee analysis of serum urea nitrogen(SUN).The modeling is based on the average effect of multiple sample partitions to achieve parameter selection with stability.A multiparameter optimization platform with Norris derivative filter-partial least squares(Norris-PLS)was developed to select the most suitable mode(d=2,s=33,g=15).Using equidistant combination PLS(EC-PLS)with four parameters(initial wavelength I,number of wavelengths N,number of wavelength gaps G and latent variables LV),we performed wavelength screening after eliminating high-absorption wavebands.The optimal EC-PLS parameters were I=1228 nm,N=26,G=16 and LV=12.The root-mean square error(SEP),correlation coefficient(R_(p))for prediction and ratio of performance-to-deviation(RPD)for validation were 1.03 mmol L^(-1),0.992 and 7.6,respectively.We proposed the wavelength step-by-step phase-out PLS(WSP-PLS)to remove redun-dant wavelengths in the top 100 EC-PLS models with improved prediction performance.The combination of 19 wavelengths was identifed as the optimal model for SUN.The SEP,Rp and RPD in validation were 1.01 mmol L^(-1),0.992 and 7.7,respectively.The prediction effect and wavelength complexity were better than those of EC-PIS.Our results showed that NIR spectroscopy combined with the EC-PLS and WSP-PLS methods enabled the high-precision analysis ofSUN.WSP-PLS is a secondary optimization method that can further optimize any wavelength moc odel obtained through other continuous or discrete strategies to establish a simple and better model.展开更多
In this paper, we present a highly efficient structure determination pipeline software suite(X^2 DF) that is based on the "Parameter space screening" method, by combining the popular crystallographic structu...In this paper, we present a highly efficient structure determination pipeline software suite(X^2 DF) that is based on the "Parameter space screening" method, by combining the popular crystallographic structure determination programs and high-performance parallel computing. The phasing method employed in X^2 DF is based on the single-wavelength anomalous diffraction(SAD) theory. In the X^2 DF, the choice of crystallographic software, the input parameters to this software and the results display layout, are all parameters which users can select and screen automatically. Users may submit multiple structure determination jobs each time, and each job uses a slightly different set of input parameters or programs. Upon completion, the results of the calculation performed can be displayed, harvested, and analyzed by using the graphical user interface(GUI) of the system. We have applied the X^2 DF successfully to many cases including the cases that the structure solutions fail to be yielded by using manual approaches.展开更多
测量环境及仪器间光谱信号的差异导致近红外光谱模型从主机传递到从机后,经常会产生过大误差。本研究提出了一种基于稳定一致波长筛选的无标样近红外模型传递方法(Screening stable and consistent wavelengths,SSCW),剔除主从仪器间差...测量环境及仪器间光谱信号的差异导致近红外光谱模型从主机传递到从机后,经常会产生过大误差。本研究提出了一种基于稳定一致波长筛选的无标样近红外模型传递方法(Screening stable and consistent wavelengths,SSCW),剔除主从仪器间差谱的标准偏差大于样品精密度测试光谱标准偏差的波长,以及精密度测试偏差过大的波长,筛选出仪器间光谱信号一致性好且稳定的波长建立近红外光谱定标模型。分别以玉米和黄芩样本集对本算法的有效性进行了检验。结果表明,SSCW模型传递后对从机样品的预测均方根残差RMSEP较全波长PLS模型直接传递结果小一个量级,大部分情况下优于分段直接校正算法(Piecewise direct standardization,PDS)的结果和文献报道的无标样模型传递结果。本方法具有传递性能好、模型参数少、稳健等优点,在不同仪器间可实现近红外光谱模型的无标样传递。展开更多
为了进一步提升近红外光谱法测定烟草绿原酸、莨菪亭、芸香苷含量的稳定性和准确性,分别采用7500~4000 cm^-1、随机蛙跳(Random Frog)和间隔随机蛙跳(Interval Random Frog)波长或波长筛选方法结合偏最小二乘(PLS)法建立了烟草中上述3...为了进一步提升近红外光谱法测定烟草绿原酸、莨菪亭、芸香苷含量的稳定性和准确性,分别采用7500~4000 cm^-1、随机蛙跳(Random Frog)和间隔随机蛙跳(Interval Random Frog)波长或波长筛选方法结合偏最小二乘(PLS)法建立了烟草中上述3种物质的近红外校正模型,并采用模型的内部参数和外部预测集样本对建模效果进行了评价。结果表明:3种物质近红外校正模型的决定系数均有一定程度提高,校正均方根误差(RMSEC)和交叉验证均方差(RMSECV)均在一定程度上降低;外部验证预测平均相对误差均在一定程度上降低。说明采用近红外光谱法测定烟草中绿原酸、莨菪亭和芸香苷时,Interval Random Frog+PLS建模效果优于Random Frog+PLS方法,后者又优于7500~4000 cm^-1光谱波长变量+PLS。展开更多
基金supported by the Science and Technology Project of Guangdong Province of China(Nos.2014A020213016,2014A020212445)the University-enterprise Joint Research Project"Intelligent detection network technology joint research centre"(No.40115031).
文摘We applied near-infrared(NIR)spectroscopy with chemometrics for the rapid and reagent-fee analysis of serum urea nitrogen(SUN).The modeling is based on the average effect of multiple sample partitions to achieve parameter selection with stability.A multiparameter optimization platform with Norris derivative filter-partial least squares(Norris-PLS)was developed to select the most suitable mode(d=2,s=33,g=15).Using equidistant combination PLS(EC-PLS)with four parameters(initial wavelength I,number of wavelengths N,number of wavelength gaps G and latent variables LV),we performed wavelength screening after eliminating high-absorption wavebands.The optimal EC-PLS parameters were I=1228 nm,N=26,G=16 and LV=12.The root-mean square error(SEP),correlation coefficient(R_(p))for prediction and ratio of performance-to-deviation(RPD)for validation were 1.03 mmol L^(-1),0.992 and 7.6,respectively.We proposed the wavelength step-by-step phase-out PLS(WSP-PLS)to remove redun-dant wavelengths in the top 100 EC-PLS models with improved prediction performance.The combination of 19 wavelengths was identifed as the optimal model for SUN.The SEP,Rp and RPD in validation were 1.01 mmol L^(-1),0.992 and 7.7,respectively.The prediction effect and wavelength complexity were better than those of EC-PIS.Our results showed that NIR spectroscopy combined with the EC-PLS and WSP-PLS methods enabled the high-precision analysis ofSUN.WSP-PLS is a secondary optimization method that can further optimize any wavelength moc odel obtained through other continuous or discrete strategies to establish a simple and better model.
文摘In this paper, we present a highly efficient structure determination pipeline software suite(X^2 DF) that is based on the "Parameter space screening" method, by combining the popular crystallographic structure determination programs and high-performance parallel computing. The phasing method employed in X^2 DF is based on the single-wavelength anomalous diffraction(SAD) theory. In the X^2 DF, the choice of crystallographic software, the input parameters to this software and the results display layout, are all parameters which users can select and screen automatically. Users may submit multiple structure determination jobs each time, and each job uses a slightly different set of input parameters or programs. Upon completion, the results of the calculation performed can be displayed, harvested, and analyzed by using the graphical user interface(GUI) of the system. We have applied the X^2 DF successfully to many cases including the cases that the structure solutions fail to be yielded by using manual approaches.
文摘测量环境及仪器间光谱信号的差异导致近红外光谱模型从主机传递到从机后,经常会产生过大误差。本研究提出了一种基于稳定一致波长筛选的无标样近红外模型传递方法(Screening stable and consistent wavelengths,SSCW),剔除主从仪器间差谱的标准偏差大于样品精密度测试光谱标准偏差的波长,以及精密度测试偏差过大的波长,筛选出仪器间光谱信号一致性好且稳定的波长建立近红外光谱定标模型。分别以玉米和黄芩样本集对本算法的有效性进行了检验。结果表明,SSCW模型传递后对从机样品的预测均方根残差RMSEP较全波长PLS模型直接传递结果小一个量级,大部分情况下优于分段直接校正算法(Piecewise direct standardization,PDS)的结果和文献报道的无标样模型传递结果。本方法具有传递性能好、模型参数少、稳健等优点,在不同仪器间可实现近红外光谱模型的无标样传递。
文摘为了进一步提升近红外光谱法测定烟草绿原酸、莨菪亭、芸香苷含量的稳定性和准确性,分别采用7500~4000 cm^-1、随机蛙跳(Random Frog)和间隔随机蛙跳(Interval Random Frog)波长或波长筛选方法结合偏最小二乘(PLS)法建立了烟草中上述3种物质的近红外校正模型,并采用模型的内部参数和外部预测集样本对建模效果进行了评价。结果表明:3种物质近红外校正模型的决定系数均有一定程度提高,校正均方根误差(RMSEC)和交叉验证均方差(RMSECV)均在一定程度上降低;外部验证预测平均相对误差均在一定程度上降低。说明采用近红外光谱法测定烟草中绿原酸、莨菪亭和芸香苷时,Interval Random Frog+PLS建模效果优于Random Frog+PLS方法,后者又优于7500~4000 cm^-1光谱波长变量+PLS。
