The buried pipelines are widely used in oil transportation. The pipelines become suspended in the river with flushing of floodwater. If the frequency of vortex shedding is near to the nature frequency of pipelines, it...The buried pipelines are widely used in oil transportation. The pipelines become suspended in the river with flushing of floodwater. If the frequency of vortex shedding is near to the nature frequency of pipelines, it will cause resonance of the suspended pipeline and result in the damage of pipelines. In this paper, the buried parts of pipeline in soil are treated as the half unlimited long beam placed on the elastic foundations. The vibration partial differential equations of suspended pipe and the parts buried in soil are derived respectively. The iterative calculation method is then presented. The results obtained from the suggested method are proved to be identical with the measured values.展开更多
We investigate the elastic waves excited by an arbitrary plane piezoelectric source on the surface of a multilayered medium. Based on the previous studies, the 2D elastic wavefield in the multilayered medium is extend...We investigate the elastic waves excited by an arbitrary plane piezoelectric source on the surface of a multilayered medium. Based on the previous studies, the 2D elastic wavefield in the multilayered medium is extended to 3D space. The propagator matrix for the 3D wavefield is investigated and the displacement-stress response for the boundary conditions is obtained. The excitation and propagation of the Rayleigh and Love waves are analysed further. It is found that the propagation velocity of the Rayleigh and Love waves does not depend on the propagation azimuth θ in the plane parallel to the free surface of the multilayered medium while the displacement is strongly dependent on the azimuth θ.展开更多
Power Sources Unlimited公司发布其Cincon系列10A和15A非隔离型负载点变换器，采用工业上标准的单列直插(SIP)或表面贴装式封装。SIP10和SMT10系列的输入电压范围是3．0V-5．5VDC，固定输出为1．0VDC到3．3VDC，输出额定电流为10A。这...Power Sources Unlimited公司发布其Cincon系列10A和15A非隔离型负载点变换器，采用工业上标准的单列直插(SIP)或表面贴装式封装。SIP10和SMT10系列的输入电压范围是3．0V-5．5VDC，固定输出为1．0VDC到3．3VDC，输出额定电流为10A。这两种版本可通过外部电阻进行电压设定，提供严格调节的0．9VDC到3．63VDC输出，以便一种器件用于多种应用。展开更多
Development of tools for targeted modifications of specific DNA sequences in plants is of great importance to basic plant biology research as well as crop improvement.The ability to cut DNA at specific locations in th...Development of tools for targeted modifications of specific DNA sequences in plants is of great importance to basic plant biology research as well as crop improvement.The ability to cut DNA at specific locations in the genome to generate doublestrand breaks（DSBs）in vivo is a prerequisite for any genome editing efforts.展开更多
文摘The buried pipelines are widely used in oil transportation. The pipelines become suspended in the river with flushing of floodwater. If the frequency of vortex shedding is near to the nature frequency of pipelines, it will cause resonance of the suspended pipeline and result in the damage of pipelines. In this paper, the buried parts of pipeline in soil are treated as the half unlimited long beam placed on the elastic foundations. The vibration partial differential equations of suspended pipe and the parts buried in soil are derived respectively. The iterative calculation method is then presented. The results obtained from the suggested method are proved to be identical with the measured values.
基金Supported by the National Natural Science Foundation of China under Grand No 10374098.
文摘We investigate the elastic waves excited by an arbitrary plane piezoelectric source on the surface of a multilayered medium. Based on the previous studies, the 2D elastic wavefield in the multilayered medium is extended to 3D space. The propagator matrix for the 3D wavefield is investigated and the displacement-stress response for the boundary conditions is obtained. The excitation and propagation of the Rayleigh and Love waves are analysed further. It is found that the propagation velocity of the Rayleigh and Love waves does not depend on the propagation azimuth θ in the plane parallel to the free surface of the multilayered medium while the displacement is strongly dependent on the azimuth θ.
基金supported by a National Transgenic Science and Technology Program (2016ZX08010002)to R.W.a startup fund from the Huazhong Agricultural University
文摘Development of tools for targeted modifications of specific DNA sequences in plants is of great importance to basic plant biology research as well as crop improvement.The ability to cut DNA at specific locations in the genome to generate doublestrand breaks（DSBs）in vivo is a prerequisite for any genome editing efforts.
