目的对比研究新型锁定钢板(LP)与有限接触动力加压钢板(LC-DCP)固定山羊新鲜胫骨时与骨骼的接触特征;对比观察LP与DCP固定对山羊胫骨横断骨折愈合的影响。方法首先分别用8孔3.5 mm LP及LC-DCP钢板固定新鲜山羊胫骨,通过压力敏感膜与应...目的对比研究新型锁定钢板(LP)与有限接触动力加压钢板(LC-DCP)固定山羊新鲜胫骨时与骨骼的接触特征;对比观察LP与DCP固定对山羊胫骨横断骨折愈合的影响。方法首先分别用8孔3.5 mm LP及LC-DCP钢板固定新鲜山羊胫骨,通过压力敏感膜与应力、图像分析系统对两种钢板与骨骼接触面积、接触压力及应力进行分析。然后采用山羊胫骨横断骨折模型,左右侧胫骨分别用8孔LP和DCP固定,术后2、8周采用X线照片观察骨折愈合情况,术后12周处死动物取出胫骨进行3点弯曲实验。结果LP与骨面接触面积较LC-DCP明显减少,两者差异有统计学意义(P<0.05),LP与骨接触应力较LC-DCP明显升高,两者差异有统计学意义(P<0.05)。固定2周时,在X线影像学上LP和DCP组骨折线均清晰可见。固定8周时,在X线影像学上LP组骨折线消失,但DCP组骨折线仍可见。术后12周,LP固定组胫骨的弯曲强度和最大载荷均大于DCP固定组,两者差异有统计学意义(P<0.05)。结论LP能有效减少与骨表面的接触面积,骨折愈合优于传统钢板。展开更多
A new multi-mesh contact algorithm for three-dimensional material point method is presented. The contact algorithm faithfully recovers the opposite acting forces between colliding bodies. Collision procedures between ...A new multi-mesh contact algorithm for three-dimensional material point method is presented. The contact algorithm faithfully recovers the opposite acting forces between colliding bodies. Collision procedures between regular bodies and/or rigid bodies are treated within the same framework. Multi-value of momentum and mass are defined on every node to describe the contact/sliding/separation procedure. Both normal and tangential velocities of each particle at the contact surface are calculated in respective individual mesh. A Coulomb friction is applied to describe the sliding or slipping between the contacting bodies. The efficiency of the contact algorithm is linearly related to the number of the contacting bodies because the overlapped nodes are labeled by sweeping the material particles of all bodies when the nodal momentum and mass are formed at every time step. Numerical simulation shows that our contact algorithm possesses high accuracy and low numerical energy dissipation, which is very important for solving collision problems.展开更多
We report the first results on 76Ge neutrinoless double beta decay from stage one of the China dark-matter experiment （CDEX）. A p-type point-contact high-purity germanium detector with a mass of 994g has been instal...We report the first results on 76Ge neutrinoless double beta decay from stage one of the China dark-matter experiment （CDEX）. A p-type point-contact high-purity germanium detector with a mass of 994g has been installed to detect neutrinoless double beta decay events, as well as to directly detect dark matter particles. An exposure of 304kgd has been analyzed over a wide spectral band from 500keV to 3MeV. The average event rate obtained was about 0.012 counts per keV per kg per day over the 2.039MeV energy range. The half-life of76Ge neutrinoless double beta decay derived based on this result is 70v2〉6.4× 1022 yr （90%C.L.）. An upper limit on the effective Majorana-neutrino mass of 5.0eV has been achieved.展开更多
文摘目的对比研究新型锁定钢板(LP)与有限接触动力加压钢板(LC-DCP)固定山羊新鲜胫骨时与骨骼的接触特征;对比观察LP与DCP固定对山羊胫骨横断骨折愈合的影响。方法首先分别用8孔3.5 mm LP及LC-DCP钢板固定新鲜山羊胫骨,通过压力敏感膜与应力、图像分析系统对两种钢板与骨骼接触面积、接触压力及应力进行分析。然后采用山羊胫骨横断骨折模型,左右侧胫骨分别用8孔LP和DCP固定,术后2、8周采用X线照片观察骨折愈合情况,术后12周处死动物取出胫骨进行3点弯曲实验。结果LP与骨面接触面积较LC-DCP明显减少,两者差异有统计学意义(P<0.05),LP与骨接触应力较LC-DCP明显升高,两者差异有统计学意义(P<0.05)。固定2周时,在X线影像学上LP和DCP组骨折线均清晰可见。固定8周时,在X线影像学上LP组骨折线消失,但DCP组骨折线仍可见。术后12周,LP固定组胫骨的弯曲强度和最大载荷均大于DCP固定组,两者差异有统计学意义(P<0.05)。结论LP能有效减少与骨表面的接触面积,骨折愈合优于传统钢板。
基金The project supported by the Science Foundation of Laboratory of Computational Physics,Science Foundation of China Academy of Engineering Physics,and National Natural Science Foundation of China under Grant Nos.10702010,10775018,10472052,and 10604010
文摘A new multi-mesh contact algorithm for three-dimensional material point method is presented. The contact algorithm faithfully recovers the opposite acting forces between colliding bodies. Collision procedures between regular bodies and/or rigid bodies are treated within the same framework. Multi-value of momentum and mass are defined on every node to describe the contact/sliding/separation procedure. Both normal and tangential velocities of each particle at the contact surface are calculated in respective individual mesh. A Coulomb friction is applied to describe the sliding or slipping between the contacting bodies. The efficiency of the contact algorithm is linearly related to the number of the contacting bodies because the overlapped nodes are labeled by sweeping the material particles of all bodies when the nodal momentum and mass are formed at every time step. Numerical simulation shows that our contact algorithm possesses high accuracy and low numerical energy dissipation, which is very important for solving collision problems.
基金supported by the National Natural Science Foundation of China(Grant Nos.11275107,11475117,11475099,and 11675088)the National Key Basic Research Program of China(Grant No.2010CB833006)
文摘We report the first results on 76Ge neutrinoless double beta decay from stage one of the China dark-matter experiment （CDEX）. A p-type point-contact high-purity germanium detector with a mass of 994g has been installed to detect neutrinoless double beta decay events, as well as to directly detect dark matter particles. An exposure of 304kgd has been analyzed over a wide spectral band from 500keV to 3MeV. The average event rate obtained was about 0.012 counts per keV per kg per day over the 2.039MeV energy range. The half-life of76Ge neutrinoless double beta decay derived based on this result is 70v2〉6.4× 1022 yr （90%C.L.）. An upper limit on the effective Majorana-neutrino mass of 5.0eV has been achieved.
