Adjusting planting density is a common agricultural practice used to achieve maximum yields. However, whether the quality of medicinal herbs can be improved by implementing appropriate planting densities is still uncertain. The medicinal crop Panax notoginseng was used to analyze the effects of planting density on growth and ginsenoside accumulation, and the possible mechanisms of these effects were revealed through metabonomics. The results showed that P. notoginseng achieved high ginsenoside accumulation at high planting densities (8 × 8 and 10 × 10 cm), while simultaneously achieved high biomass and ginsenoside accumulation at moderate planting density of 15 × 15 cm. At the moderate planting density, the primary metabolism (starch and sucrose metabolism) and secondary metabolism (the biosynthesis of phytohormone IAA and ginsenoside) of the plants were significantly enhanced. However, the strong intraspecific competition at the high planting densities resulted in stress as well as the accumulation of phytohormones (SA and JA), antioxidants (gentiobiose, oxalic acid, dehydroascorbic acid) and other stress resistance-related metabolites. Interestingly, the dry biomass and ginsenoside content were significantly lower at low densities (20 × 20 and 30 × 30 cm) with low intraspecific competition, which disturbed normal carbohydrate metabolism by upregulating galactose metabolism. In summary, an appropriate planting density was benefit for the growth and accumulation of ginsenosides in P. notoginseng by balancing primary metabolism and secondary metabolism.

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In order to diagnose the mechanical fault of transformer on‐load tap‐changer (OLTC) effectively, a fault diagnosis method based on improved variational mode decomposition (VMD) and relative density‐based outlier score (RDOS) is proposed. Firstly, the signal is decomposed into a series of modal components with narrow band and distinguishing centre frequency by improved VMD based on optimal quality factor. Then, the energy, permutation entropy, power spectrum concentration degree and characteristic frequency of each modal component are calculated, and Laplacian‐score method is used to select the features with better discriminative ability. Finally, a RDOS is used to diagnose the mechanical fault of OLTC, and the mechanical condition is judged according to RDOS value. An experiment is conducted on the OLTC simulation experiment platform and the collected signals are processed. The result shows that the proposed method can diagnose mechanical fault effectively.

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