Tunnels are now an integral part of the infrastructure in major cities around the world. For many reasons, these tunnels have horseshoe-shaped cross-sections with round top and flat bottom. This paper presents some im...Tunnels are now an integral part of the infrastructure in major cities around the world. For many reasons, these tunnels have horseshoe-shaped cross-sections with round top and flat bottom. This paper presents some improvements to the use of the Hyperstatic Reaction Method-HRM for analysing tunnels with horseshoe-shaped cross-sections when these tunnels operate under the influence of earthquakes, particularly in cases when the tunnel lining is a continuous lining. The analysis used parameters of a tunnel from the Hanoi metro system, as well as parameters of the strongest earthquake that may occur in the central Hanoi area in the improved HRM and 2 D numerical methods using the ABAQUS software. On the basis of the results obtained, the paper gives conclusions about the HRM methodology when it is used to calculate tunnels that have horseshoe cross-sections operating under the influence of earthquakes.展开更多
Measurements were performed of K-shell ionization cross sections of Ti element by 10～30 keV positron impact using the thick-target method. The effects of multiple scattering of incident positron and from bremsstrahlu...Measurements were performed of K-shell ionization cross sections of Ti element by 10～30 keV positron impact using the thick-target method. The effects of multiple scattering of incident positron and from bremsstrahlung photons and annihilation photons with the thick-target method are discussed with the Monte Carlo code PENELOPE. Meanwhile, the Monte Carlo method is also applied to determine the detection efficiencies of X- and γ-ray detectors. Our experimental K-shell ionization cross sections for Ti element are compared with the distorted-wave Born approximation （DWBA） theoretical predictions, and it is found that the agreement of the experimental data and theoretical values is good and this indicates that the experimental method adopted in this study is applicable.展开更多
A method to deal with the electron impact excitation cross sections of an atom from low to high incident energies are presented. This method combines the partial wave method and the first Born approximation(FBA), i.e....A method to deal with the electron impact excitation cross sections of an atom from low to high incident energies are presented. This method combines the partial wave method and the first Born approximation(FBA), i.e., replacing the several lowest partial wave cross sections of the total cross sections within FBA by the corresponding exact partial wave cross sections. A new set of codes are developed to calculate the FBA partial wave cross sections. Using this method,the convergent e–He collision cross sections of optical-forbidden and optical-allowed transitions at low to high incident energies are obtained. The calculation results demonstrate the validity and efficiency of the method.展开更多
为合理评估山岭隧道施工阶段的辐射对施工人员的影响,通过测试隧道内环境的γ辐射剂量率、空气氡浓度、粉尘质量浓度、围岩放射性核素比活度等环境参数,以工人年均个人剂量为主要评估指标,推荐了一套基于新奥法施工的山岭隧道施工阶段...为合理评估山岭隧道施工阶段的辐射对施工人员的影响,通过测试隧道内环境的γ辐射剂量率、空气氡浓度、粉尘质量浓度、围岩放射性核素比活度等环境参数,以工人年均个人剂量为主要评估指标,推荐了一套基于新奥法施工的山岭隧道施工阶段辐射对施工人员影响的评估方法。运用该方法对摩岗岭隧道不同施工工序下的各项辐射指标进行测试和评估,研究得出:摩岗岭隧道施工人员各工序年均个人剂量为0.203~1.13 m Sv,隧道内部辐射环境对施工人员的影响处于较低范围。该评估方法不仅考虑了隧道不同工序施工人员接受辐射时间、辐射来源等问题,而且辐射指标的选取符合山岭隧道施工的实际情况,对隧道穿越辐射异常区的施工安全和辐射防治具有指导作用。展开更多
基金supported by the Saint Petersburg Mining University
文摘Tunnels are now an integral part of the infrastructure in major cities around the world. For many reasons, these tunnels have horseshoe-shaped cross-sections with round top and flat bottom. This paper presents some improvements to the use of the Hyperstatic Reaction Method-HRM for analysing tunnels with horseshoe-shaped cross-sections when these tunnels operate under the influence of earthquakes, particularly in cases when the tunnel lining is a continuous lining. The analysis used parameters of a tunnel from the Hanoi metro system, as well as parameters of the strongest earthquake that may occur in the central Hanoi area in the improved HRM and 2 D numerical methods using the ABAQUS software. On the basis of the results obtained, the paper gives conclusions about the HRM methodology when it is used to calculate tunnels that have horseshoe cross-sections operating under the influence of earthquakes.
基金supported by National Natural Science Foundation of China (Nos.10674097,10774106)
文摘Measurements were performed of K-shell ionization cross sections of Ti element by 10～30 keV positron impact using the thick-target method. The effects of multiple scattering of incident positron and from bremsstrahlung photons and annihilation photons with the thick-target method are discussed with the Monte Carlo code PENELOPE. Meanwhile, the Monte Carlo method is also applied to determine the detection efficiencies of X- and γ-ray detectors. Our experimental K-shell ionization cross sections for Ti element are compared with the distorted-wave Born approximation （DWBA） theoretical predictions, and it is found that the agreement of the experimental data and theoretical values is good and this indicates that the experimental method adopted in this study is applicable.
基金supported by the National Basic Research Program of China(Grant Nos.2011CB921501 and 2013CB922200)the National Natural Science Foundation of China(Grant Nos.11274035,11275029,11328401,11371218,11474031,11474032,and 11474034)the Foundation of Development of Science and Technology of Chinese Academy of Engineering Physics(Grant Nos.2013A0102005 and 2014A0102005)
文摘A method to deal with the electron impact excitation cross sections of an atom from low to high incident energies are presented. This method combines the partial wave method and the first Born approximation(FBA), i.e., replacing the several lowest partial wave cross sections of the total cross sections within FBA by the corresponding exact partial wave cross sections. A new set of codes are developed to calculate the FBA partial wave cross sections. Using this method,the convergent e–He collision cross sections of optical-forbidden and optical-allowed transitions at low to high incident energies are obtained. The calculation results demonstrate the validity and efficiency of the method.
文摘为合理评估山岭隧道施工阶段的辐射对施工人员的影响,通过测试隧道内环境的γ辐射剂量率、空气氡浓度、粉尘质量浓度、围岩放射性核素比活度等环境参数,以工人年均个人剂量为主要评估指标,推荐了一套基于新奥法施工的山岭隧道施工阶段辐射对施工人员影响的评估方法。运用该方法对摩岗岭隧道不同施工工序下的各项辐射指标进行测试和评估,研究得出:摩岗岭隧道施工人员各工序年均个人剂量为0.203~1.13 m Sv,隧道内部辐射环境对施工人员的影响处于较低范围。该评估方法不仅考虑了隧道不同工序施工人员接受辐射时间、辐射来源等问题,而且辐射指标的选取符合山岭隧道施工的实际情况,对隧道穿越辐射异常区的施工安全和辐射防治具有指导作用。
