Study On Near Infrared Measurement Technology Applied To Grain Analysis

In this paper, first the evolution of near infrared measurement technology and its application in grain analysis are expatiated. Then the molecule vibration foundation of the near infrared spectrum and the spectrum character of the organic compound were theoretically described. Further the diffused reflection spectrum parameters and the Kubelka-Munk(K-M) function were analyzed. And the analytical method was introduced for the multiple-components based samples by using diffused reflection absorbency as the spectrum parameter. Finally, Chemometrics methods frequently employed in this work were summarized and the criterion of the grain components was confirmed. The focus of this work was to design and manufacture the near infrared spectrum analyzer for grain components with filters. The construction and the operation manner of the analyzer are main concerns in this work and the dominant parts contain: a lamp, a filters and a detector. The performance of these parts is then optimized and the parameters were chosen for these important parts in the paper. The capability of a homemade analyzer was compared with the advanced FOSS near infrared grating grain analyzer. Two problems were studied and solved in the development process as follows: 1) The bandwidth of the homemade analyzer is about 20nm. The bandwidth of FOSS analyzer is about 7nm. With 94 soybean samples, the protein, fat and water of soybean samples were calibrated and examined by using import TQ-AnalystV6 software and homemade administrant system software. The calibration and prediction results were analyzed. According to the results obtained by standard chemical method, the standard error of the prediction and calibration resulted from the homemade analyzer and homemade software was closed to the standard error resulted from the import analyzer and software. It is concluded that the technical levels of the two analyzers are very closed to each other. In order to explore the relation between the bandwidth and the examined results, the Fourier Transform Spectrophotometer with optional resolution is employed to scan the wheat powder at 2cm-1,4 cm-1,8 cm-1,16 cm-1 and 32 cm-1 resolutions. The conclusion is that the measured results of protein content are not influenced by the value of the resolution. 2) In order to guarantee the veracity of the measurement, in the current measurement, the constant of the calibration equation was everyday required to be modified by the samples whose standard chemical constant needed to be known when the near infrared spectrophotometer with the filters as the prismatic apparatus was used in practice. A sort of the resolve was to keep the instrument and the samples at constant temperature. But it is time-consuming and costly. For the sake of improving the roboticized degree of instruments and stinting the metrical time, the homemade interference-filter based near infrared grain component analyzer was employed to scanned the wheat powdered samples at temperature of 4℃, 8℃, 14℃, 19℃, 22℃and 29℃. The correctional model functioning the temperature was founded for analyzing the content of wheat protein and 45 wheat samples at different environment temperatures were used in measurement. This model was alsocompared with both the model obtained at room temperature(22 ℃) and the temperature insensitive model based on stepwise linear regression. The results show that the mean standard error of prediction (SEP) of the temperature correctional model was smallest, so this model can improve the analysis precision availably. As well, the model can guarantee the veracity of the measurement via software method without increasing the hardware cost. In the course of the study and the manufacturing for the homemade interference-filter based near infrared grain component analyzer, the experiments of spectrometer bandwidth and the experiments at different environment temperatures were analyzed. The conclusion was that the bandwidth does not influence the analytical results and the temperature correctional model can improve the analytical precision. The results obtained in this work build a foundation for the experimental and the theoretical studies for the near-infrared measurement technology. They can be used as a reference when the near infrared analyzer is designed and used in site or on line.