Abstract: A directly rapid quantitative analysis method for chemical oxygen demand (COD) of wastewater samples was established by near-infrared (NIR) spectroscopy and partial least square (PLS) method. The optimization of Savitzky-Golay (SG) smoothing modes combined with PLS factor was applied to optimize the model of NIR spectroscopy analysis here. The waveband used for modeling was the combination of 400-1878 nm and 2088-2338 nm. The optimal smoothing parameters were the 5th derivative smoothing, 5th degree polynomial, 17 smoothing points, the optimal PLS factor, root mean squared error of predication (RMSEP) and correlation coefficient of predication (RP) were 7, 33.2 (mg/L) and 0.929 respectively, which was obviously superior to the direct PLS model without SG smoothing and ones based on the whole spectral collecting region 400-2500 nm. This demonstrated that NIR spectroscopy can be applied to the rapid determination of COD of wastewater, large-scale simultaneous optimization selection of SG smoothing parameters and PLS factor can be effectively applied to the model optimization of NIR analysis.
Abstract: .Soil properties are very absent and sorely needed for many models. Conventional measurements are expensive and many samples are required. Hence it is difficult to quantitatively analysis them at a large-scale region. Hyperspectral methods are now used for the rapid characterization of a wide range of soil. In this paper, it was used to estimate organic matter content in soil of Heihe River basin. A total of 84 samples were collected and their reflected spectral were measured with ASD spectrometers. Then the organic matter were predicted using four forms of spectra and PLS method. The results show:1) the hyperspectral remote sensing can be used to predict soil organic matter content, and the precision can meet the requirement; 2) the best region of spectrum is 400~800nm in R, 1/R and Log (1/R) formation, and the FDR and FD(Log (1/R)) centered in 800nm based on the correlation coefficient and Variable Importance in Projection.
Abstract: For lack of short-wavelength-IR bands near 2.1μm, the operational capabilities of HJ-1A/B CCD in monitoring aerosols are limited overwhelmingly. To solve this problem, a new algorithm, using MODIS surface reflectance production (MOD09) to support HJ-1A/B CCD aerosol retrieval, is proposed. A model of determining HJ-1 A/B CCD surface reflectance at blue band using MODIS surface reflectance data based on the kernel-based BRDF model is proposed. Six different HJ-1A/B CCD images, which have a high-quality and cover almost all the areas in Beijing, are used to test the new method. The retrieved values are compared with the API of Beijing city. Both of them have a similar variation trend. Implementation of the algorithm has a great significance in promoting the operational running of monitoring aerosol