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Given the increase in mining depth and intensity, tunnel failure as a result of rock burst has become an important issue in the field of mining engineering in China. Based on the Composite Rock-Bolt Bearing Structure, which is formed due to the interaction of the bolts driven into the surrounding rock, this paper analyzes a rock burst prevention mechanism, establishes a mechanical model in burst-prone ground, deduces the strength calculation formula of the Composite Rock-Bolt Bearing Structure in burst-prone ground, and confirms the rock burst prevention criterion of the Composite Rock-Bolt Bearing Structure. According to the rock burst prevention criterion, the amount of the influence on rock burst prevention ability from the surrounding rock parameters and bolt support parameters is discussed.

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A method is proposed to calibrate a planar phased array by reconstructing its aperture distribution, in which the aperture distribution is superposed within the physical range of radiating element. Consequently, the calibration coefficients are solved for the linear relationship between the superposed aperture distribution and elements' excitations. The calibration accuracy that is influenced by resolution of aperture distribution is also discussed in this paper. In practice, the reconstruction procedure of aperture distribution is based on the plane wave spectrum (PWS) theory, utilizing FFT and IFFT techniques. This method turns out to be valid by experiment.

A novel single-layer band-pass frequency selective surface (FSS) is proposed in this letter. The unit cell is composed of eight rotationally symmetrical fishbone-shaped structures surrounded by a modified octagonal loop. This fishbone-shaped FSS exhibits stable resonant frequency while the incident angle ranges from 0 • to 60 • for both TE and TM polarizations, which means that polarization insensitivity and angular stability are well demonstrated on the proposed FSS. A prototype is fabricated and measured in an anechoic chamber, and good agreements are obtained between measured and simulated results.