A B S T R A C TTicks are medically-important arthropods that maintain and transmit numerous emerging viruses. China suffers severely from tick-borne viral diseases such as tick-borne encephalitis and severe fever with thrombocytopenia syndrome (SFTS), but the background of tick-borne viruses is very limited. Here we report the virome profiling of ticks and goat sera from SFTS-epidemic areas, and serological investigation of SFTS virus (SFTSV) and Nairobi sheep disease virus (NSDV). Results revealed divergent viruses in ticks and goat sera, including SFTSV and NSDV. Sequence and phylogenetic analyses showed that the SFTSV identified here was most closely related to human SFTSV in sampling and surrounding areas, and the NSDV to the previously identified NSDV from northeast China. Serological investigation of SFTSV infection in goats revealed intensive activity in those areas. Surprisingly, two different methods of NSDV serological investigation showed no sera positive for this virus.
High-power DC relays are widely used in new energy power systems and DC distribution networks, and commonly use transverse magnetic fields to accelerate arc extinguishing. In this paper, the magnetically blown arc characteristics and the resulting contact erosion mechanisms of high-power DC relays are studied by experiments and simulations. The experiments are carried out to analyze the arc motion, contact erosion mass, and contact morphologies, and to verify the simulation model. Considering the energy transfer source term, the establishment of a more perfect magnetohydrodynamic arc model is accomplished, and an erosion model is further established. The results indicate that the magnetically blown arcing process has three stages while the arc shapes and motion characteristics are different, and the heat flux acting on the contact can be accurately obtained by the arc model. The greater external transverse magnetic field is more conducive to extinguishing the arc and reducing the arc erosion time. In contrast, the Archimedes force plays a very small positive role and the self-induced magnetic field of the arc has a negative effect. For contact erosion, the temperature distribution of the molten pool appears trailing effect. Moreover, the advanced mathematical model proposed for erosion mass has good accuracy. The calculation results of erosion rates show that Cr reduces erosion while the current increases erosion nonlinearly. Besides, the flow and deformation characteristics of the molten pool will lead to convex strip-shaped erosion traces and arcing position transfer, and the moving erosion will cause the lateral accretion effect. Furthermore, the analysis shows that the reason for edge droplet sputtering is the pressure difference caused by Plateau-Rayleigh instability, and optimization suggestions for reducing contact erosion are given.
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