Analysis of key warning points and environmental conditions for the '4.04'strong downburst event in Hengyang of Hunan

On the afternoon of 4 April, 2023, an intense downburst event (referred to as the '4.04' strong downburst) occurred in Hengyang, Hunan, causing serious disasters. This study analyzes the key warning indicators and environmental conditions for extreme strong winds using conventional meteorological observations, Doppler weather radar, and NCEP 1°×1° reanalysis data. The results are as follows: (1) The '4.04' strong downburst occurred under a 'baroclinic frontogenesis' weather system configuration, with a surface cold front providing the triggering conditions. The Skew-T plots clearly showed characteristics of high-level dryness and low-level moisture, unstable atmospheric convective parameters, and corrected convective available potential energy (CAPE), along with strong vertical wind shear, all conducive to the occurrence of extreme strong winds. (2) A mesoscale convective system (MCS) with bow echoes swept through Hengyang, causing regional downbursts. Extreme strong winds occurred when the corresponding storm cells moved rapidly, with maximum reflectivity factors reaching 60 dBz. The vertical integrated liquid water content and centroid height rapidly decreased. The reflectivity factors displayed a noticeable tilted structure, with clear features of bow echoes, rear-inflow jets, and radial velocity ambiguity. The low elevation asymmetric high-speed regions and velocity convergence are key warning indicators for extreme strong winds. (3) The strong downburst exhibited significant convective potential, with strong low-level moisture flux convergence and high specific humidity. There were conditions of thermal instability and vertical upward motion, along with low-level convergence and upper-level divergence. Cold air played an important role in the occurrence and development of this downburst event

Tetrahedral Lithium Stuffing in Disordered Rocksalt Cathodes for High-Power-Density and Energy-Density Batteries

Li-rich cation-disordered rocksalt (DRX) materials introduce new paradigms in the design of high-capacity Li-ion battery cathode materials. However, DRX materials show strikingly sluggish kinetics due to random Li percolation with poor rate performance. Here, we demonstrate that Li stuffing into the tetrahedral sites of the Mn-based rocksalt skeleton injects a novel tetrahedron-octahedron-tetrahedron diffusion path, which acts as a low-energy-barrier hub to facilitate high-speed Li transport. Moreover, the enhanced stability of lattice oxygen and the suppression of transition metal migration preserve the efficacy of the Li percolation network during cycling. Overall, the tetrahedral Li stuffing DRX material exhibits high energy density (311 mAh g-1, 923 Wh kg-1) and high power density (251 mAh g-1, 697 Wh kg-1 at 1000 mA g-1). Our results highlight the potential to develop high-performance and earth-abundant cathode materials within the extensive range of rocksalt compounds

Research and Prospect of 5G Power Application

This paper investigates the 5G power application status in China, and compares the mainstream communication technologies of the existing power system, such as wired, 4G, wifi, 5G and so on. Effectively combined the advantages of 5G technology with power applications, the paper clarifies the application scenarios of 5G in the power system. The research focuses on typical power applications under the background of new power system construction, including intelligent inspection, distribution network protection and control, distributed energy grid connection and dispatching stability control, and analyzes the technical indicators and economy of various typical applications. Finally, this paper analyzes the challenges faced by 5G power application, and proposes solutions, as well as prospects for 5G power application.</jats:p