Based on the Navier-Stokes （N-S） equations of incompressible viscous fluids and the standard k-ε turbu- lence model with assumptions of steady state and two dimensional conditions, a simulation of the aerodynamic d...Based on the Navier-Stokes （N-S） equations of incompressible viscous fluids and the standard k-ε turbu- lence model with assumptions of steady state and two dimensional conditions, a simulation of the aerodynamic drag on a maglev train in an evacuated tube was made with ANSYS/FLOTRAN software under different vacuum pressures, blockage ratios, and shapes of train head and tail. The pressure flow fields of the evacuated tube maglev train under different vacuum pressures were analyzed, and then compared under the same blockage ratio condition. The results show that the environmental pressure of 1 000 Pa in the tube is the best to achieve the effect of aerodynamic drag reduction, and there are no obvious differences in the aerodynamic drag reduction among different streamline head shapes. Overall, the blunt-shape tail and the blockage ratio of 0.25 are more efficient for drag reduction of the train at the tube pressure of 1 000 Pa.展开更多
本研究以通过花粉管通道法获得的Bt+Sck双价基因棉转基因植株为材料,利用改进的TAIL-PCR方法扩增T-DNA插入位点左、右边界的侧翼序列,结果表明:T-DNA侧翼序列均包含一段载体骨架序列;T-DNA插入区富含A,T碱基对,并且属于核基质结合区(Bin...本研究以通过花粉管通道法获得的Bt+Sck双价基因棉转基因植株为材料,利用改进的TAIL-PCR方法扩增T-DNA插入位点左、右边界的侧翼序列,结果表明:T-DNA侧翼序列均包含一段载体骨架序列;T-DNA插入区富含A,T碱基对,并且属于核基质结合区(Bind to nuclear matrices);T-DNA整合到棉花基因组后,其左、右边界均有缺失。花粉管通道转化的机理很复杂,该试验为进一步研究此转化方法提供了一种实用的研究方法。展开更多
基金supported by the Program for Changjiang Scholars and Innovative Research Team in University(PCSIRT) of the Ministry of Education of China(IRT0751)the National High Technology Research and Development Program of China (863 program: 2007-AA03Z203)+2 种基金the National Natural Science Foundation of China (Grant Nos. 50588201 and 50872116)the Research Fund for the Doctoral Program of Higher Education of China (SRFDP200806130023)the Fundamental Research Funds for the Central Universities (SWJTU09BR152, SWJTU09ZT24, and SWJTU11CX073)
文摘Based on the Navier-Stokes （N-S） equations of incompressible viscous fluids and the standard k-ε turbu- lence model with assumptions of steady state and two dimensional conditions, a simulation of the aerodynamic drag on a maglev train in an evacuated tube was made with ANSYS/FLOTRAN software under different vacuum pressures, blockage ratios, and shapes of train head and tail. The pressure flow fields of the evacuated tube maglev train under different vacuum pressures were analyzed, and then compared under the same blockage ratio condition. The results show that the environmental pressure of 1 000 Pa in the tube is the best to achieve the effect of aerodynamic drag reduction, and there are no obvious differences in the aerodynamic drag reduction among different streamline head shapes. Overall, the blunt-shape tail and the blockage ratio of 0.25 are more efficient for drag reduction of the train at the tube pressure of 1 000 Pa.
文摘本研究以通过花粉管通道法获得的Bt+Sck双价基因棉转基因植株为材料,利用改进的TAIL-PCR方法扩增T-DNA插入位点左、右边界的侧翼序列,结果表明:T-DNA侧翼序列均包含一段载体骨架序列;T-DNA插入区富含A,T碱基对,并且属于核基质结合区(Bind to nuclear matrices);T-DNA整合到棉花基因组后,其左、右边界均有缺失。花粉管通道转化的机理很复杂,该试验为进一步研究此转化方法提供了一种实用的研究方法。
