The distribution of velocity is one of the basic issues in river dynamics.Based on the experimental data measured by ADV in the flume of State Key Hydraulics Laboratory (SKHL),this paper analyzed the ver- tical distri...The distribution of velocity is one of the basic issues in river dynamics.Based on the experimental data measured by ADV in the flume of State Key Hydraulics Laboratory (SKHL),this paper analyzed the ver- tical distribution of point velocity and the varying law of turbulence intensity in straight mobile compound chan- nel with an asymmetric floodplain.Above certain relative height,the streamwise point velocity follows the loga- rithmic distribution.Below the location,the velocity varies linearly approxim...展开更多
Gold disk targets were irradiated using focusing and beam smoothing methods on Xingguang (XG-Ⅱ) laser facilities with 350 nm wavelength,0.6 ns pulse width and 20-80 Joules energies. Laser absorption,light scattering ...Gold disk targets were irradiated using focusing and beam smoothing methods on Xingguang (XG-Ⅱ) laser facilities with 350 nm wavelength,0.6 ns pulse width and 20-80 Joules energies. Laser absorption,light scattering and X-ray conversion were experimentally investigated. The experimental results showed that laser ab-sorption and scattered light were about 90% and 10%,respectively,under focusing irradiation,but the laser absorption increased 5%-10% and the scattered light about 1% under the condition of beam smoothing. Compared with the case of fo-cusing irradiation,the laser absorption was effectively improved and the scattered light remarkably dropped under uniform irradiation; then due to the decrease in laser intensity,X-ray conversion increased. This is highly advantageous to the in-ertial confinement fusion. However,X-ray conversion mechanism basically did not change and X-ray conversion efficiency under beam smoothing and focusing irra-diation was basically the same.展开更多
为研究隧道截面形式对隧道围岩的影响,结合模型试验和数值模拟研究高宽比K变化时,马蹄形隧道围岩稳定性及损伤破坏规律。考虑隧道周边无宏观裂纹和含有单一裂纹2种情况,数值模拟采用ABAQUS混凝土塑性损伤模型,计算隧道周边应力;对含有...为研究隧道截面形式对隧道围岩的影响,结合模型试验和数值模拟研究高宽比K变化时,马蹄形隧道围岩稳定性及损伤破坏规律。考虑隧道周边无宏观裂纹和含有单一裂纹2种情况,数值模拟采用ABAQUS混凝土塑性损伤模型,计算隧道周边应力;对含有裂纹的情况利用J积分计算出裂纹尖端应力强度因子,利用ABAQUS中XFEM(extended finite element method)扩展有限元技术模拟高宽比为1.5时裂纹的发展路径和应力分布,与模型试验吻合较好。结果表明:隧道围岩的稳定性和损伤破坏情况随隧道高宽比K的变化而变化,对无裂纹模型,试件抗压强度在K=1.5时最大,K=1.0时最小;对有裂纹隧道模型,试件抗压强度在K=1.7时最大,K=0.7时最小。展开更多
基金Supported by Key Project of Chinese.Ministry of Education (03134)
文摘The distribution of velocity is one of the basic issues in river dynamics.Based on the experimental data measured by ADV in the flume of State Key Hydraulics Laboratory (SKHL),this paper analyzed the ver- tical distribution of point velocity and the varying law of turbulence intensity in straight mobile compound chan- nel with an asymmetric floodplain.Above certain relative height,the streamwise point velocity follows the loga- rithmic distribution.Below the location,the velocity varies linearly approxim...
文摘Gold disk targets were irradiated using focusing and beam smoothing methods on Xingguang (XG-Ⅱ) laser facilities with 350 nm wavelength,0.6 ns pulse width and 20-80 Joules energies. Laser absorption,light scattering and X-ray conversion were experimentally investigated. The experimental results showed that laser ab-sorption and scattered light were about 90% and 10%,respectively,under focusing irradiation,but the laser absorption increased 5%-10% and the scattered light about 1% under the condition of beam smoothing. Compared with the case of fo-cusing irradiation,the laser absorption was effectively improved and the scattered light remarkably dropped under uniform irradiation; then due to the decrease in laser intensity,X-ray conversion increased. This is highly advantageous to the in-ertial confinement fusion. However,X-ray conversion mechanism basically did not change and X-ray conversion efficiency under beam smoothing and focusing irra-diation was basically the same.
文摘为研究隧道截面形式对隧道围岩的影响,结合模型试验和数值模拟研究高宽比K变化时,马蹄形隧道围岩稳定性及损伤破坏规律。考虑隧道周边无宏观裂纹和含有单一裂纹2种情况,数值模拟采用ABAQUS混凝土塑性损伤模型,计算隧道周边应力;对含有裂纹的情况利用J积分计算出裂纹尖端应力强度因子,利用ABAQUS中XFEM(extended finite element method)扩展有限元技术模拟高宽比为1.5时裂纹的发展路径和应力分布,与模型试验吻合较好。结果表明:隧道围岩的稳定性和损伤破坏情况随隧道高宽比K的变化而变化,对无裂纹模型,试件抗压强度在K=1.5时最大,K=1.0时最小;对有裂纹隧道模型,试件抗压强度在K=1.7时最大,K=0.7时最小。
