[Analysis of infrared spectroscopy of ginsengs by support vector machine and wavelet transform]

In the present study, 40 samples of ginsengs (20 samples from Jian and 20 samples from Fushun) were surveyed by Fourier transform infrared (IR) spectroscopy. Meanwhile, in order to eliminate the spectral differences from the baseline drifts, the original ginseng spectra were processed using first derivative method. To avoid enhancing the noise resulting from the derivative the spectra were smoothed. This smoothing was done by using the Savitzky-Golay algorithm, a moving window averaging method. Artificial neural network (ANN), support vector machine (SVM) as the new pattern recognition technology, and wavelet transform (WT) were applied. Firstly, the spectrum variables of infrared spectroscopy were compressed through the WT technology before the models were established, in order to reduce the time in establishing models. Then, the identification models of cultivation area of ginsengs were studied comparatively by the use of ANN and SVM methods. The corresponding important parameters of models were also discussed in detail, including the parameters of wavelet compressing and training parameters of ANN and SVM models. The simulation experiment indicated that the ANN model can carry on the distinction among 40 samples of ginsengs from Jilin, and the accuracy rate of identification was 92.5%. The radial basis function (RBF) SVM classifiers and the polynomial SVM classifiers were studied comparatively in this experiment. The best experimental results were obtained using RBF SVM classifier with sigma = 0.6, and the accuracy rate of identification was 97.5%. Finally, compared with ANN approach, SVM algorithm showed its excellent generalization for identification results while the number of samples was smaller. The overall results show that IR spectroscopy combined with SVM and WT technology can be efficiently utilized for rapid and simple identification of the cultivation area of ginsengs, and thus provides the certain technology support and the foundation for further researching ginseng and other IR applications.