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In this paper we carried out experiments using two-stage light gas gun with Gram-grade cylindrical tungsten alloy projectiles, impacting concrete targets at velocity from 1.82 km/s to 3.66 km/s ton investigate the cratering mechanism of concrete targets in hypervelocity impact conditions. We obtained the penetration depth and residual length of the projectiles using computerized tomography (CT) and used the numerical simulation results conducted by Euler algorithm to further examine the mechanism of hypervelocity impact, and achieved the following results: (1) The craters were structured by spalling areas and bullet holes; (2) The penetration depth increases at first and then decreases with the increase of the impact velocities, and the maximum penetration depth was 8.5 times that of the projectile length, which showed no significant advantage over low velocity penetration; (3) According to the pressure of the interface of the projectiles and targets, the penetration processes were divided into four stages, of which the quasi-steady stage and the third stage were crucial in determining the total penetration depth; (4) When the projectiles were completely eroded with the increase of the impact velocities, the penetration depth of the quasi-steady stages almost remained the same and the penetration depth of the third stage decreased so that the total penetration depth was observed to increase at first and then decrease. 相似文献
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本文研究了 Rh B分子的 539.0 nm和 572 .5nm两荧光峰在表面增强活性银胶颗粒表面上的增强和淬灭效应 :在同一分子体系中同时观察到 530 .0 nm荧光峰的增强和 572 .5nm荧光峰的淬灭 ,并对其进行了理论计算。结果表明这两个荧光峰的增强或淬灭主要取决于局域电磁场增强和分子到金属表面无辐射能量转移衰减过程的竞争效应。当满足吸收共振增强和辐射共振增强时 ,荧光被增强 ;反之 ,荧光被淬灭。计算表明 ,荧光增强因子最高为 1 相似文献
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