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Objective. To get the spatio-temporal distribution of the syphilis epidemic in 31 provinces, municipalities directly under the Central Government and autonomous regions of the mainland of China in 2017. Methods. The data of syphilis incidence in 31 provinces, municipalities and autonomous regions of the mainland of China in 2017 were obtained from the China Public Health Science Data Center, and the time distrbution characteristics of the incidence rates were described. The global Moran's I index and Anselin local Moran's I index were used to analyze the spatial cluster characteristics of the syphilis cases, and then space-time scan analysis based on Poisson distribution was used to explore the spatio-temporal distribution characteristics. Results. In 2017, the number of syphilis cases in the 31 provinces, municipalities, and autonomous regions of the mainland of China was 475 860, and the incidence rate was 34.49/100 000. Latent syphilis accounted for most of the cases, reaching 76.78% (365 353/475 860). August had the highest incidence rate. For the spatial distribution, Xinjiang Uygur Autonomous Region was the provincial-level unit with the highest incidence rate of syphilis, reaching 91.80/100 000. The incidence rates of latent, secondary, tertiary, and congenital syphilis appeared with positive spatial autocorrelation (all P<0.05). The high-high clusters of secondary and tertiary syphilis appeared in Shanghai, Jiangsu, and Zhejiang (all P<0.05), respectively, while the high-high clusters of congenital syphilis appeared in Xinjiang and Tibet (P=0.000). The results of space-time scan analysis showed that the main cluster appeared from April to September in Fujian, Jiangxi, Zhejiang, Shanghai, Jiangsu, Hunan, Anhui, and Guangdong (P=0.000). Compared with the outside area, the relative risk of syphilis in this cluster was 1.59 times. Conclusion. The incidence rate of syphilis in China is relatively high. There are differences in the types and periods of syphilis prevention and control among provinces, municipalities and autonomous regions. From April to September, Fujian, Jiangxi, Zhejiang, Shanghai, Jiangsu, Hunan, Anhui and Guangdong are the key areas for syphilis prevention and control in the mainland of China. [ABSTRACT FROM AUTHOR]

This paper proposed a small current to ground fault line selection method with time-frequency atom and grey correlation analysis. Firstly, it calculated the base values of fault line and non-fault line based on the number of branch line of small current to ground system. Secondly, it used the matching pursuit method to decompose the transient zero-sequence current of the first 1/4 cycle indexed by Gabor atom, and calculated the damped sinusoidal atoms of every branch line which expressed the characteristic of fault state. Thirdly, it used the theory of grey relational analysis to compute the correlation degree of every damped sinusoidal atom, and got the characteristic value of every branch line. Finally, it calculated the Euclidean distance value between the characteristic values and the base values of fault line and non-fault line, and compared the size of Euclidean distance values to achieve the fault line selection accurately. The method has a lower computational complexity, an accurate fault selection proved by a large number of simulations. It is especially suitable for the multi-branch lines of small current to ground system. [ABSTRACT FROM AUTHOR]