目的验证基于临床CT的数字体相关(digital volume correlation,DVC)方法在测量股骨内部变形场时的准确性,并通过DVC进一步测量股骨在跌倒情况下的内部变形,验证基于临床CT的有限元分析方法(finite element analysis,FEA)在计算股骨内部...目的验证基于临床CT的数字体相关(digital volume correlation,DVC)方法在测量股骨内部变形场时的准确性,并通过DVC进一步测量股骨在跌倒情况下的内部变形,验证基于临床CT的有限元分析方法(finite element analysis,FEA)在计算股骨内部变形场的准确性。方法使用猪股骨,模拟侧向跌倒姿态,进行分步力学加载实验,同步进行多次CT成像。通过重复扫描和虚拟位移验证DVC方法的准确性。DVC以子体积作为配准两组图像的研究对象,分别设置8、12、16和20 mm的子体积进行测试。量化误差指标包括位移系统误差-平均值(mean)、位移随机误差-标准差(standard deviation,SD)、应变准确度-平均绝对误差(mean absolute error,MAER)和应变精确度-标准差误差(standard deviation of the error,SDER)。基于CT图像建立股骨有限元模型,模拟实验条件,计算股骨内部位移,与DVC测量的内部变形场对比验证。结果基于临床CT的DVC方法重复扫描位移偏差小于0.013 mm,MAER和SDER均小于200με;虚拟位移偏差小于0.098 mm,MAER为1093~1687με,SDER为604~1267με,远小于骨组织屈服应变。FEA计算的位移和DVC测量的位移之间具有较强的相关性(R^(2)≥0.76,P<0.05)。结论基于临床CT的DVC方法可以准确测量股骨内部变形场,并且基于临床CT的有限元模型可以准确计算股骨内部变形场。展开更多
Employing the recoil ion momentum spectroscopy we investigate the collision between He^2＋ and argon atoms. By measuring the recoil longitudinal momentum the energy losses of projectile are deduced for capture reactio...Employing the recoil ion momentum spectroscopy we investigate the collision between He^2＋ and argon atoms. By measuring the recoil longitudinal momentum the energy losses of projectile are deduced for capture reaction channels. It is found that in most cases for single- and double-electron capture, the inner electron in the target atom is removed, the recoil ion is in singly or multiply excited states （hollow ion is formed）, which indicates that electron correlation plays an important role in the process. The captured electrons prefer the ground states of the projectile. It is experimentally demonstrated that the average energy losses are directly related to charge transfer and electronic configuration展开更多
State-selective single electron capture cross sections are measured by recoil ion momentum spectroscopy technique for He^2＋ on He at 30keV incident energy. The cross sections for capture into ground and excited state...State-selective single electron capture cross sections are measured by recoil ion momentum spectroscopy technique for He^2＋ on He at 30keV incident energy. The cross sections for capture into ground and excited states are obtained and compared to classical model calculations as well as to the quantum mechanical calculations. The experimental results are in good agreement with quantum mechanical results.展开更多
We experimentally observe the signature of electron emission resulting from a single binary encounter mechanism in the intermediate collision energy regime of 30 keV/u He2＋ on argon. Electron emission spectra in the ...We experimentally observe the signature of electron emission resulting from a single binary encounter mechanism in the intermediate collision energy regime of 30 keV/u He2＋ on argon. Electron emission spectra in the transfer ionization are obtained and compared with classical calculations from a two-step model considering the initial electron velocity and re-scattering of the binary encounter electron in the recoil potential. Although the present reaction is actually a four-body problem, the model starting from a binary encounter gives out surprisingly good agreement with the experimental data. Our studies show that orbital velocities of the electron affect the emission patterns of ionized electrons significantly.展开更多
We report the study on the complete three-body Coulomb explosion(CE)of N_(2)O^(q+)(q=5,6)induced by 56-keV/u Ne8+ion collision with N2O gaseous molecule.Six CE channels for N_(2)O^(5+)and seven for N_(2)O^(6+)are iden...We report the study on the complete three-body Coulomb explosion(CE)of N_(2)O^(q+)(q=5,6)induced by 56-keV/u Ne8+ion collision with N2O gaseous molecule.Six CE channels for N_(2)O^(5+)and seven for N_(2)O^(6+)are identified by measuring three ionic fragments and the charge-changed projectile in quadruple coincidence.Correspondingly the kinetic energy release(KER)and momentum correlation angle(MCA)distributions of three ionic fragments for each of the CE channels are also deduced.Numerical computation is presented to reconstruct the geometric structure of N_(2)O^(q+0prior to dissociation based on the measured KER and MCA.The N–N and N–O bond lengths and the N–N–O bond angles of N_(2)O^(q+)for each of the channels are determined.展开更多
文摘目的验证基于临床CT的数字体相关(digital volume correlation,DVC)方法在测量股骨内部变形场时的准确性,并通过DVC进一步测量股骨在跌倒情况下的内部变形,验证基于临床CT的有限元分析方法(finite element analysis,FEA)在计算股骨内部变形场的准确性。方法使用猪股骨,模拟侧向跌倒姿态,进行分步力学加载实验,同步进行多次CT成像。通过重复扫描和虚拟位移验证DVC方法的准确性。DVC以子体积作为配准两组图像的研究对象,分别设置8、12、16和20 mm的子体积进行测试。量化误差指标包括位移系统误差-平均值(mean)、位移随机误差-标准差(standard deviation,SD)、应变准确度-平均绝对误差(mean absolute error,MAER)和应变精确度-标准差误差(standard deviation of the error,SDER)。基于CT图像建立股骨有限元模型,模拟实验条件,计算股骨内部位移,与DVC测量的内部变形场对比验证。结果基于临床CT的DVC方法重复扫描位移偏差小于0.013 mm,MAER和SDER均小于200με;虚拟位移偏差小于0.098 mm,MAER为1093~1687με,SDER为604~1267με,远小于骨组织屈服应变。FEA计算的位移和DVC测量的位移之间具有较强的相关性(R^(2)≥0.76,P<0.05)。结论基于临床CT的DVC方法可以准确测量股骨内部变形场,并且基于临床CT的有限元模型可以准确计算股骨内部变形场。
基金Supported by the National Natural Science Foundation of China under Grant No 10434100. The experiment would not be finished without the help of the ECR team. The authors would like to thank Professor Jianguo Wang and Professor Burhard Fricke for many helpful discussions.
文摘Employing the recoil ion momentum spectroscopy we investigate the collision between He^2＋ and argon atoms. By measuring the recoil longitudinal momentum the energy losses of projectile are deduced for capture reaction channels. It is found that in most cases for single- and double-electron capture, the inner electron in the target atom is removed, the recoil ion is in singly or multiply excited states （hollow ion is formed）, which indicates that electron correlation plays an important role in the process. The captured electrons prefer the ground states of the projectile. It is experimentally demonstrated that the average energy losses are directly related to charge transfer and electronic configuration
基金Supported by the National Natural Science Foundation of China under Grant No 10434100,
文摘State-selective single electron capture cross sections are measured by recoil ion momentum spectroscopy technique for He^2＋ on He at 30keV incident energy. The cross sections for capture into ground and excited states are obtained and compared to classical model calculations as well as to the quantum mechanical calculations. The experimental results are in good agreement with quantum mechanical results.
基金Supported by the National Basic Research Program of China under Grant No 2010CB832902the National Natural Science Foundation of China under Grants Nos U1332128 and 11274317,10979007 and 11004202the Program of One Hundred Talents of the Chinese Academy of Sciences
文摘We experimentally observe the signature of electron emission resulting from a single binary encounter mechanism in the intermediate collision energy regime of 30 keV/u He2＋ on argon. Electron emission spectra in the transfer ionization are obtained and compared with classical calculations from a two-step model considering the initial electron velocity and re-scattering of the binary encounter electron in the recoil potential. Although the present reaction is actually a four-body problem, the model starting from a binary encounter gives out surprisingly good agreement with the experimental data. Our studies show that orbital velocities of the electron affect the emission patterns of ionized electrons significantly.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2017YFA0402300 and 2017YFA0303501)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB34000000)。
文摘We report the study on the complete three-body Coulomb explosion(CE)of N_(2)O^(q+)(q=5,6)induced by 56-keV/u Ne8+ion collision with N2O gaseous molecule.Six CE channels for N_(2)O^(5+)and seven for N_(2)O^(6+)are identified by measuring three ionic fragments and the charge-changed projectile in quadruple coincidence.Correspondingly the kinetic energy release(KER)and momentum correlation angle(MCA)distributions of three ionic fragments for each of the CE channels are also deduced.Numerical computation is presented to reconstruct the geometric structure of N_(2)O^(q+0prior to dissociation based on the measured KER and MCA.The N–N and N–O bond lengths and the N–N–O bond angles of N_(2)O^(q+)for each of the channels are determined.
