The anchor stress extent of a prestress anchor cable project has a direct relation with the project safety and performance. Prestressed tensioning method is a kind of nondestructive testing method, by which a reverse ...The anchor stress extent of a prestress anchor cable project has a direct relation with the project safety and performance. Prestressed tensioning method is a kind of nondestructive testing method, by which a reverse stretching load is applied on the external exposure section of anchor cable under construction or in service, and then the elongation variation of stress bars is measured to determine the anchor stress. We elaborated the theory and testing mechanism of prestressed tensioning method, and systematically studied key issues during the prestressed tensioning process of anchor cable by using physical model test, including the composition of tension stress-elongation curve, the variation of anchor stress, the compensation of locked anchor stress, and the judgment of anchor stress, and verified the theory feasibility of prestressed tensioning method. A case study on slope anchor cable of one highway project was conducted to further discuss on the test method, operation procedures and judgment of prestressed tensioning method on obtaining anchor stress, and then the test data of three situations were analyzed. The result provides a theoretical basis and technical base for the application of prestressed tensioning method to the evaluation of construction quality and operation conditions of anchor cable project.展开更多
An in-situ TiCp/Al composite was prepared by a thermal explosion/quick pressure method （TE/QP）. The effect of Al content on the reaction temperature as well as the reaction rate has been studied. Phase constituents ...An in-situ TiCp/Al composite was prepared by a thermal explosion/quick pressure method （TE/QP）. The effect of Al content on the reaction temperature as well as the reaction rate has been studied. Phase constituents and the microstructure of the composites and the particle size of the reinforcement were analysed using X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The results have shown that TiCp/Al composite with 40～70 vol. pct TiC particle reinforcement and high relative density can be directly obtained by TE/QP. TiC is the only reaction product when Al content in Al-Ti-C system is no more than 60 vol. pct, but Al3Ti phase will also form when Al content is more than 60 vol. pct. Increasing Al content prolongs the initial reaction time, reduces the highest reaction temperature and the reaction rate, and decreases the size of TiC particles. In addition, the microstructure of TiCp/Al composite and the structure of interface between TiCp and Al are studied using SEM and transmission electron microscopy （TEM）. The results show that the in-situ synthesized TiC particle has fcc cubic structure. The orientation between TiC particles and Al matrix can be described as （220）Al//（022）TiC and [112]Al//[011]TiC. Results of the mechanical property tests reveal that the ultimate strength （σ） and modulus （E） are 687 MPa and 142 GPa respectively when the Al content is 40 vol. pct. On contrary, 6 elongation increases by 3.2% with increasing Al content.展开更多
In this study,measurements of the^(128)Te(n,2n)^(127m,g)Te reaction cross sections and the computation of the isomeric cross section ratio were performed around the neutron energy of 13−15 MeV.We used aγ-ray spectrom...In this study,measurements of the^(128)Te(n,2n)^(127m,g)Te reaction cross sections and the computation of the isomeric cross section ratio were performed around the neutron energy of 13−15 MeV.We used aγ-ray spectrometric technique to conduct the measurements.The neutron energy was produced by the^(3)H(d,n)^(4)He reaction.For the^(128)Te(n,2n)^(127m,g)Te reaction,the excited state,ground state,total cross section,and isomeric cross section ratio were determined using the TALYS-1.96 code,a theoretical nuclear model that allows for variations in density options.The initial experimental data,assessed nuclear data,and theoretical calculations based on the TALYS-1.96 algorithm were compared with the measurement results.The new data produced by this study are essential for validating nuclear models and establishing parameters for nuclear reactions.展开更多
基金Funded by the Science and Technolog Program of Ministry of Transport of P.R.China(No.2012318352100)
文摘The anchor stress extent of a prestress anchor cable project has a direct relation with the project safety and performance. Prestressed tensioning method is a kind of nondestructive testing method, by which a reverse stretching load is applied on the external exposure section of anchor cable under construction or in service, and then the elongation variation of stress bars is measured to determine the anchor stress. We elaborated the theory and testing mechanism of prestressed tensioning method, and systematically studied key issues during the prestressed tensioning process of anchor cable by using physical model test, including the composition of tension stress-elongation curve, the variation of anchor stress, the compensation of locked anchor stress, and the judgment of anchor stress, and verified the theory feasibility of prestressed tensioning method. A case study on slope anchor cable of one highway project was conducted to further discuss on the test method, operation procedures and judgment of prestressed tensioning method on obtaining anchor stress, and then the test data of three situations were analyzed. The result provides a theoretical basis and technical base for the application of prestressed tensioning method to the evaluation of construction quality and operation conditions of anchor cable project.
文摘An in-situ TiCp/Al composite was prepared by a thermal explosion/quick pressure method （TE/QP）. The effect of Al content on the reaction temperature as well as the reaction rate has been studied. Phase constituents and the microstructure of the composites and the particle size of the reinforcement were analysed using X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The results have shown that TiCp/Al composite with 40～70 vol. pct TiC particle reinforcement and high relative density can be directly obtained by TE/QP. TiC is the only reaction product when Al content in Al-Ti-C system is no more than 60 vol. pct, but Al3Ti phase will also form when Al content is more than 60 vol. pct. Increasing Al content prolongs the initial reaction time, reduces the highest reaction temperature and the reaction rate, and decreases the size of TiC particles. In addition, the microstructure of TiCp/Al composite and the structure of interface between TiCp and Al are studied using SEM and transmission electron microscopy （TEM）. The results show that the in-situ synthesized TiC particle has fcc cubic structure. The orientation between TiC particles and Al matrix can be described as （220）Al//（022）TiC and [112]Al//[011]TiC. Results of the mechanical property tests reveal that the ultimate strength （σ） and modulus （E） are 687 MPa and 142 GPa respectively when the Al content is 40 vol. pct. On contrary, 6 elongation increases by 3.2% with increasing Al content.
基金Supported by the National Natural Science Foundation of China(12165006,12375295)。
文摘In this study,measurements of the^(128)Te(n,2n)^(127m,g)Te reaction cross sections and the computation of the isomeric cross section ratio were performed around the neutron energy of 13−15 MeV.We used aγ-ray spectrometric technique to conduct the measurements.The neutron energy was produced by the^(3)H(d,n)^(4)He reaction.For the^(128)Te(n,2n)^(127m,g)Te reaction,the excited state,ground state,total cross section,and isomeric cross section ratio were determined using the TALYS-1.96 code,a theoretical nuclear model that allows for variations in density options.The initial experimental data,assessed nuclear data,and theoretical calculations based on the TALYS-1.96 algorithm were compared with the measurement results.The new data produced by this study are essential for validating nuclear models and establishing parameters for nuclear reactions.
文摘采用改进的垂直布里奇曼生长法生长Cd Zn Te(CZT)单晶,并在晶体生长后期采取长时间的原位恒温退火.采用红外透射显微镜、I-V特性曲线以及多道能谱仪测试经过原位退火后的晶体内部Te夹杂相分布、电阻率大小以及能谱响应.结果表明,原位退火可以大幅降低CZT晶体内部大尺寸Te夹杂相的密度,晶体内绝大部分的Te夹杂都集中在5μm以内.此外,原位退火后的晶体电阻率从4.54×108Ω·cm上升至3.73×1010Ω·cm.原位退火后的CZT晶体对241Am@59.5 ke Vγ射线表现出了良好的能量分辨率,为7.29%.
基金supported by The National High Technology Research and Development(No.2006AA12Z135)National Nature Science Foundation of China(Nos.10334030 and 60225004)Knowledge Innovation Program of Chinese Academy of Sciences(Nos.C2-38 and C2-22).
基金Projects (50872111, 50902113, 61274081) supported by the National Natural Science Foundation of ChinaProject (2011CB610406) supported by the National Basic Research Program of China+2 种基金Project (B08040) supported by the 111 Project of ChinaProject (JC20100228) supported by Foundation for Fundamental Research of Northwestern Polytechnical University (NPU), ChinaProject (SKLSP201012) supported by the Research Fund of the State Key Laboratory of Solidification Processing (NPU), China
