A theoretical investigation on the structural and elastic properties of ZnO nanotubes is carried out by using atomistic calculations based on an inter-atomic pair potential within the shell-model approach. The calcula...A theoretical investigation on the structural and elastic properties of ZnO nanotubes is carried out by using atomistic calculations based on an inter-atomic pair potential within the shell-model approach. The calculation results are presented for the bond length, bond angle, radius dilation, strain energy, Young modulus and Poisson ratio as a function of tube radius. For small tube radius these properties depend on the helicity of the tube, while for the tube radius larger than 6.0A, they are independent of the tube radius and helicity except for the strain energy which decreases with increasing tube radius.展开更多
A computational fluid dynamics(CFD)numerical simulation and field experiment were used to investigate optimal operating parameters of high-pressure jet grouting equipment and clarify the boundary law of the injection ...A computational fluid dynamics(CFD)numerical simulation and field experiment were used to investigate optimal operating parameters of high-pressure jet grouting equipment and clarify the boundary law of the injection area in the remediation process.The response surface optimization design results show that the optimal injection pressure is 30 MPa,rotation speed is 23 r/min,commission speed is 30 cm/min,and the optimal injection diameter is 147.3 cm.Based on the CFD numerical simulation,the ratio of the injection core,turbulent zone,and seepage zone is approximately 1∶4∶2.The distribution law of jet core,turbulence zone and seepage zone at different cross-sections under 30 MPa operating conditions is as follows:The jet core radius is approximately 100 mm,the turbulence zone is mainly distributed at 100 to 500 mm,the seepage zone is mainly distributed at 500 to 700 mm,the seepage zone could be completed within 2 h,and the proportion of the three boundary zones in the injection zone is similar to that of the numerical simulation.This study provides theoretical parameters and practical reference for the remediation of deep pollution via in-situ chemical oxidation in the Loess Plateau soil environment.展开更多
建立一种管式炉内燃烧石油焦样品前处理,然后用自动碘量库仑滴定法测定石油焦中总硫含量的方法。探讨了影响实验结果的因素,电解液采用10 m L冰乙酸溶解于250 m L蒸馏水中,避光保存,实验环境温度为20℃以上,电解液中搅拌转子的转速为500...建立一种管式炉内燃烧石油焦样品前处理,然后用自动碘量库仑滴定法测定石油焦中总硫含量的方法。探讨了影响实验结果的因素,电解液采用10 m L冰乙酸溶解于250 m L蒸馏水中,避光保存,实验环境温度为20℃以上,电解液中搅拌转子的转速为500 r/min。在优化的实验条件下,测定结果的相对标准偏差在2.36%~3.94%(n=6)之间,3种石油焦样品加标回收率在82.0%~101.5%之间。该方法可应用于石油焦中总硫含量的测定。展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 10025420, 10574121 and 90406024, the Ministry of Education of China, and Chinese Academy of Sciences.
文摘A theoretical investigation on the structural and elastic properties of ZnO nanotubes is carried out by using atomistic calculations based on an inter-atomic pair potential within the shell-model approach. The calculation results are presented for the bond length, bond angle, radius dilation, strain energy, Young modulus and Poisson ratio as a function of tube radius. For small tube radius these properties depend on the helicity of the tube, while for the tube radius larger than 6.0A, they are independent of the tube radius and helicity except for the strain energy which decreases with increasing tube radius.
基金The National Natural Science Foundation of China(No.41967043,52160003)the Natural Science Foundation of Gansu Province(No.20JR5RA461)+1 种基金the Key Project of China Railway Southwest Research Institute Co.,Ltd.(No.2018-KJ003-Z003-XB)the Industrial Support Program of the Higher Education of Gansu Province(No.2020C-40).
文摘A computational fluid dynamics(CFD)numerical simulation and field experiment were used to investigate optimal operating parameters of high-pressure jet grouting equipment and clarify the boundary law of the injection area in the remediation process.The response surface optimization design results show that the optimal injection pressure is 30 MPa,rotation speed is 23 r/min,commission speed is 30 cm/min,and the optimal injection diameter is 147.3 cm.Based on the CFD numerical simulation,the ratio of the injection core,turbulent zone,and seepage zone is approximately 1∶4∶2.The distribution law of jet core,turbulence zone and seepage zone at different cross-sections under 30 MPa operating conditions is as follows:The jet core radius is approximately 100 mm,the turbulence zone is mainly distributed at 100 to 500 mm,the seepage zone is mainly distributed at 500 to 700 mm,the seepage zone could be completed within 2 h,and the proportion of the three boundary zones in the injection zone is similar to that of the numerical simulation.This study provides theoretical parameters and practical reference for the remediation of deep pollution via in-situ chemical oxidation in the Loess Plateau soil environment.
文摘建立一种管式炉内燃烧石油焦样品前处理,然后用自动碘量库仑滴定法测定石油焦中总硫含量的方法。探讨了影响实验结果的因素,电解液采用10 m L冰乙酸溶解于250 m L蒸馏水中,避光保存,实验环境温度为20℃以上,电解液中搅拌转子的转速为500 r/min。在优化的实验条件下,测定结果的相对标准偏差在2.36%~3.94%(n=6)之间,3种石油焦样品加标回收率在82.0%~101.5%之间。该方法可应用于石油焦中总硫含量的测定。
