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With the large-scale application of composite materials in aircraft structures, the threat of visually invisible damage such as internal delamination of composite materials caused by impact from foreign objects is increasing,therefore, impact event monitoring and impact location identification of composite reinforced structures is essential.In order to verify the engineering validity of the impact localization algorithm, based on the piezoelectric sensing signal of the impact test on the composite large wall plate structure, the localization accuracy of the time-reversal focusing,error function and cross-correlation function impact monitoring algorithms is compared. The results show that, in the monitoring area of 2 360 mm×1 260 mm, the error of the cross-correlation function algorithm is smaller than that of the time-reversal focusing algorithm, and the error of the time-reversal focusing algorithm is larger at the truss, which is not suitable for impact positioning of reinforced structures.

In order to select and cultivate germplasm resources of Leymus chinensis suitable for planting in Hinggan League area, four wild Leymus chinensis germplasm resources from different geographical distribution in Hinggan League were tested for phenological characteristics, morphological indexes, quantitative indexes and nutritional indexes, and correlation analysis and comprehensive evaluation were carried out. The results showed that both morphological and quantitative traits had different degrees of variation, ranging from 2.11%~43.10%. Among the nutritional indexes, the coefficient of variation of dry matter is the smallest, which is 0.26%. The coefficient of variation of crude protein is the highest, which is 20.94%. There was a significant positive correlation between plant height and leaf width (P<0.05) and extremely significant positive correlation with dry weight (P<0.01). The ranking of weighted correlation degree was YC01> YC02>YC04>YC03. The study indicates that YC01 germplasm has good production performance and comprehensive performance in Hinggan League. [ABSTRACT FROM AUTHOR]