As a chemical detection technology for analysis of in-situ, real time and multiple materials, Laser Raman Spectroscopy is competent to take quantitative research for ingredients in ocean environment, and achieve long-term in-situ supervision of acid radical ionic concentration in seawater. Due to the inevitable interference in the actual detection environment, the spectral data often contains some outliers, the existence of which has a significant impact on the performance of the quantitative analysis model. In order to remove the outliers accurately in the in-situ detection and online analysis, the MMD algorithm was combined with the PLS quantitative analysis model (PLS-MMD model) to detect and remove the outliers in the calibration set. It was demonstrated that the PLS-MMD method can effectively eliminate the abnormal spectra in the calibration data. After removing outliers the accuracy of the measured seawater sample concentration was improved with the relative error decreasing from 1.468% to 1.160%. Correspondingly, the prediction stability of in-situ seawater is also improved.
Ocean optics discusses the light transmission in seawater, which is a specialty course combining optics and ocean study, and the core course of relevant professional directions. This paper introduces its learning goal and contents. Meanwhile, it also discusses adding study project lecture series and investigating study to realize scientific research back feeding traditional learning. This would further inspire students' interest, cultivate students' innovation and practice ability, and enable them to lay a solid foundation of professional theory.
Laser-induced breakdown spectroscopy (LIBS) has been shown to be a useful technique in elemental analysis with many
advantages including rapid analysis, simultaneous multi-element detection, in-situ or stand-off analysis capability. To
evaluate the potential application of LIBS for quantitative analysis, some experimental investigations into the laser
induced plasma process were undertaken with brass alloy sample, in the laboratory. The plasma was generated by a
Q-switched Nd:YAG laser operating at 532 nm with pulse width of 10ns and repeat frequency of 10 Hz. The LIBS signal
was coupled to the spectrometer and recorded with OMA system and a PMT in conjunction with a computer controlled
Boxcar integrator. The temporal characteristic of the plasma was investigated with the emission line of Cu atom at
324.75 nm, 327.40 nm and the emission line of Zn atom at 330.25 nm. The optimum delay time range for 324.75 nm
from Cu atoms and 330.25 nm from Zn atoms is from 300 to 600 ns. The self-absorption of Cu atomic lines at 324.75 nm
and 327.40 nm can be reduced by increasing the laser energy and recording the spectra in the early stage of the plasma
formation. The experimental results are effective for improving the slope of calibration curve.
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