Conventional chemical methods to detect pesticide residue are complex, and need professional instruments as well as much time. NIR spectral analysis provides an effective way for pesticide residue detection because of simple operation, rapid analysis and non-destruction of samples. However, conventional calibration models are only effective after spectra were measured, and different models are needed for different instruments. In this study, we propose a novel calibration transfer method by using sequential forward selection to transfer calibration models between different crops and instruments. The calibration model built by master instrument can identify three kinds of pesticide including Chlorothalonil, Chlorpyrifos and Buprofezin. Spectra obtained by slave instrument can also be predicted by the models with the method. The experiment results show that the prediction accuracies increased from 50% up to 80% by using our method.
Dynamic Acquisition of multi-spectral light field image with high resolution, is a conundrum in Computational Photography. In this paper, we propose a multispectral imaging system based on multi-view light field rendering. The hardware system architecture consists of equidistantly fixed camera array and various spectral filters, and we use an algorithm based on frequency domain pyramid decomposition to calculate the disparity at different view angles. So we can realize the cross-channel image matching so as to obtain the single- view image under the multi-spectral channel and achieve the high-resolution real-time multi-spectral imaging.
Sheets of AZ31B wrought magnesium alloy were welded by CO2 laser. Welds of "partial penetration", "weld pool
penetration", "keyhole penetration" and "excessive penetration" were obtained, and the "keyhole penetrated" weld
possessed the best quality. The light emission of welding plasma was monitored by photo-diode, and it was found that
the photo-diode signal varied with different penetration statuses. When the welds were "weld pool penetrated" and
"keyhole penetrated", the average signal amplitude
A reached its minimum value. R, which defined as ratio of
A and standard deviation δs of signal was introduced to describe the fluctuation tendency of
plasma, and the ratio reached its maximum value (which meant the lowest plasma stability) when welds were "weld pool
penetrated". By detecting the minimum value of
A and R, "keyhole penetration" can be differentiated from "weld
pool penetration" and "excessive penetration".