The on-line measurement of the main component contents is essential for production, detection and identification of compound fertilizer. Using developed VIS-NIR sensors for on-line measurement of the main component contents in compound fertilizer, primary results about nitrogen (N), phosphorus pentoxide (P2O5) and potassium oxide (K2O) were reported. A visible (VIS) and near infrared (NIR) spectrophotometer (Ocean Optics), with a measurement range of 360.18–2221.53 nm was used to measure fertilizer spectra in reflectance mode. By using principal component analysis (PCA) and mahalanobis distance method, 3 outlier samples were detected and eliminated from 174 samples firstly. Then these models of three components with the 124 samples in calibration set were established using principal component regress (PCR) and partial least squares regression (PLS) coupled respectively with the full cross-validation technique after preprocessing the original spectrum with different methods. These models were used to estimate the contents of N, P2O5 and K2O of the other 47 samples in predicted set. The research results showed that the method could be applied to rapid measurement to the main component contents in compound fertilizer. Compared with the traditional analysis method, the on-line measurement could do it rapidly, inexpensively and pollution-freely. It suggested the potential use of the VIS–NIR sensing system for on-line measurement in the production, detection and identification process of compound fertilizer.
A developed in situ measuring system uses light emitted diodes (LED) and laser diodes(LD) as light sources is employed
for the recording of algae chlorophyll fluorescence induction kinetics (Kautsky-effect). Photosynthesis activity as an
important parameter is obtained in the system which measures the chlorophyll fluorescence yield. Minimal fluorescence
is excited by the brief but really weak light pulses from LED as measure light while photosynthesis is happened, variable
fluorescence which means there is energy conversion through photosynthesis is also excited by a LED but the beam is
more stronger, LD induced saturation fluorescence stands for maximum fluorescence. The system could works for alga
chlorophyll photosynthesis activity continuous measure in situ through efficiently mechanical and optical design.
The laser-induced breakdown spectroscopy emission characteristics of trace heavy metal lead in water is studied based
on graphite conch method, with a 1064nm wavelength Nd: YAG laser as excitation source, the echelle spectrometer and
ICCD detector are used for spectral separation and high sensitive detection with high resolution and wide spectral range.
The delay time 900ns and gate time 1600ns are determined in the experiment. The calibration curve of Pb is plotted
based on the different concentration measurement results, and a limit of detection of 0.0138mg / L is obtained for Pb in
water. Graphite conch method effectively overcomes the current problems on laser-induced breakdown spectroscopy
detection of heavy metal in water. The detection limits and stability are improved. The reference data is provided for
further study on the fast measurement of trace heavy metals in water by laser induced breakdown spectroscopy
technique.
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