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Broadband and ultra-low reflection metamaterial absorber embedded with magnetic materials
Zhou Wei,Zhu Zhenghou,Zou Qiang,Yuan Zhifen,Liu Rongyu 한국물리학회 2022 Current Applied Physics Vol.41 No.-
In this study, we design, prepare and characterize a broadband, ultra-low reflectivity and incidence angle-insensitive metamaterial absorber. The design of this absorber not only provides a novel idea for the design of broadband absorbers, but also enhances the application prospects of metamaterial absorbers. By introducing FeSiAlp/epoxy magnetic composite and optimizing the structural parameters, the absorption performance of the metamaterial absorber has been significantly improved. The effective absorption bandwidth (bandwidth with reflectivity less than -10dB) is increased by 3.4 times from 2.19 GHz to 7.49 GHz, and the RLmin (minimum reflection loss) value reaches -38.31 dB at 17.83 GHz, that is the absorption rate reaches 99.99%. Meanwhile, the experimental results also verify the simulation design results. Therefore, the absorber not only plays the characteristics of strong absorption of metamaterial, but also absorbs the advantages of broadband of magnetic material.
Zhengjun Mao,Xiaokang Wang,Ning An,Xiaojun Li,Rongyu Wei 대한토목학회 2019 KSCE Journal of Civil Engineering Vol.23 No.10
The water disaster susceptible areas in loess multi-arch tunnels were studied. Taking Lishi multi-arch tunnel as an example, the tunnel is located in Luliang City, Shanxi Province, China, with a total length of 180 m. It is the first loess multi-arch tunnel in China. The groundwater recharge in the tunnel site is dominated by rainfall, and the surrounding rock of the tunnel is unsaturated. Considering the lateral recharge of groundwater, in this study, midas geo-technical analysis system was adopted to simulate the construction process of a middle pilot tunnel–bilateral pilot tunnel of a loess multi-arch tunnel, accounting for fluid-solid coupling. The variations in the surrounding rock stress and seepage fields of loess multi-arch tunnels during the construction process were studied. A water disaster susceptible area in a loess multi-arch tunnel was confirmed based on the catastrophe area of the displacement, stress, gross head, pore water pressure, and seepage velocity. The result show that the water disaster susceptible areas for loess multi-arch tunnels during the construction period mainly concentrated in the mid-partition, arch springs of the left and right tunnels, and the tunnel face.