The localization of damage for bridges to ensure their safety is investigated in this paper. Equivalent element concept is introduced into this study at the beginning. Support reaction data of each bearing under truck...The localization of damage for bridges to ensure their safety is investigated in this paper. Equivalent element concept is introduced into this study at the beginning. Support reaction data of each bearing under truck load are found to be able to lend themselves to indicate damage. A novel index termed as symmetrical support reaction difference index （SSRDI） is then developed. The reverse mapping between the local flexurai stiffness change induced by damage and the SSRDI is generated. The proposed method based on SSRDI can be sensitive to tiny damages, and comparatively simple measurements are required during the application procedure. Another significant attraction of this method is that it can work in the presence of random uncertainties and actual support condition, which means it is suitable for real-world bridges. The effectiveness of the proposed method is demonstrated by numerical simulations performed on two kinds of bridges with reasonable damage severities. Its comparative advantage over the previous frequency method is also investigated.展开更多
Probabilistic analysis is a rational approach for engineering design because it provides more insight than traditional deterministic analysis. Probabilistic evaluation on seismic stability of three dimensional (3D) sl...Probabilistic analysis is a rational approach for engineering design because it provides more insight than traditional deterministic analysis. Probabilistic evaluation on seismic stability of three dimensional (3D) slopes is studied in this paper. The slope safety factor is computed by combining the kinematic approach of limit analysis using a three-dimensional rotational failure mechanism with the pseudo-dynamic approach. The variability of input parameters, including six pseudo-dynamic parameters and two soil shear strength parameters, are taken into account by means of Monte-Carlo Simulations (MCS) method. The influences of pseudo-dynamic input variables on the computed failure probabilities are investigated and discussed. It is shown that the obtained failure probabilities increase with the pseudo-dynamic input variables and the pseudo-dynamic approach gives more conservative failure probability estimates compared with the pseudo-static approach.展开更多
This paper presents a probabilistic reliability method for the welded shell during crack growth. The crack growth model incorporated with a failure assessment diagram（FAD） , which can provides a better estimation of...This paper presents a probabilistic reliability method for the welded shell during crack growth. The crack growth model incorporated with a failure assessment diagram（FAD） , which can provides a better estimation of the critical crack length, is developed to describe fatigue failure. All variables for particular welded joints of the shell are studied. Among them, the stress variables are based on the calculated stress by using the finite element （FE） code ANSYS. Fatigue reliability analysis of the welded shell is performed by using the Monte Carlo simulation method. The failure probability curve of the example kiln is significantly useful to determine the repair schedule of shell cracks.展开更多
Uranium enrichment determination by non-destructive assay is an important method in authenticating the nuclear warhead or uranium component in deep nuclear reduction verifications.In this paper,the feasibility of appl...Uranium enrichment determination by non-destructive assay is an important method in authenticating the nuclear warhead or uranium component in deep nuclear reduction verifications.In this paper,the feasibility of applying the high-energy photon interrogation to determine the uranium enrichment is studied.Simplified models are presented which were simulated by particle Monte Carlo transport code.The results indicate that the relation curves of the released neutrons and the enrichment of uranium objects are almost linear.For a uranium object of a given shape,the uranium enrichment can be obtained with the relation curves,which could be got in advance by calibration experiments or simulations.展开更多
The charged lepton flavor violation process is a clean and sensitive probe of new physics beyond the Standard Model. A sensitivity study is performed to the process τ^-→γμ^- based on a 3 fb^(-1) inclusive Monte Ca...The charged lepton flavor violation process is a clean and sensitive probe of new physics beyond the Standard Model. A sensitivity study is performed to the process τ^-→γμ^- based on a 3 fb^(-1) inclusive Monte Carlo sample of e^+e^- collisions at a center-of-mass energy of4.26 or 4.6 Ge V, in the framework of the BESIII software system. The 90 % confidence level upper limits on B(τ^-→γμ^-) are estimated assuming no signal is produced. We also obtain the sensitivity on B(τ^-→γμ^-) as a function of the integrated luminosity, to serve as a reference for the HIEPA being proposed in China. It is found that 6.34 ab^(-1) are needed to reach the current best upper limit of 4:4 10^(-8) and about 2510 ab^(-1) are needed to reach a sensitivity of 10^(-9) if the detector design is similar to that of BESIII.展开更多
基金National Key Basic Research and Development Program of China (973 program) (No. 2002CB412709)
文摘The localization of damage for bridges to ensure their safety is investigated in this paper. Equivalent element concept is introduced into this study at the beginning. Support reaction data of each bearing under truck load are found to be able to lend themselves to indicate damage. A novel index termed as symmetrical support reaction difference index （SSRDI） is then developed. The reverse mapping between the local flexurai stiffness change induced by damage and the SSRDI is generated. The proposed method based on SSRDI can be sensitive to tiny damages, and comparatively simple measurements are required during the application procedure. Another significant attraction of this method is that it can work in the presence of random uncertainties and actual support condition, which means it is suitable for real-world bridges. The effectiveness of the proposed method is demonstrated by numerical simulations performed on two kinds of bridges with reasonable damage severities. Its comparative advantage over the previous frequency method is also investigated.
文摘Probabilistic analysis is a rational approach for engineering design because it provides more insight than traditional deterministic analysis. Probabilistic evaluation on seismic stability of three dimensional (3D) slopes is studied in this paper. The slope safety factor is computed by combining the kinematic approach of limit analysis using a three-dimensional rotational failure mechanism with the pseudo-dynamic approach. The variability of input parameters, including six pseudo-dynamic parameters and two soil shear strength parameters, are taken into account by means of Monte-Carlo Simulations (MCS) method. The influences of pseudo-dynamic input variables on the computed failure probabilities are investigated and discussed. It is shown that the obtained failure probabilities increase with the pseudo-dynamic input variables and the pseudo-dynamic approach gives more conservative failure probability estimates compared with the pseudo-static approach.
基金National Natural Science Foundation of China(No.51075140)Scientific Research Fund of Hunan Provincial Education Department(No.09C407)
文摘This paper presents a probabilistic reliability method for the welded shell during crack growth. The crack growth model incorporated with a failure assessment diagram（FAD） , which can provides a better estimation of the critical crack length, is developed to describe fatigue failure. All variables for particular welded joints of the shell are studied. Among them, the stress variables are based on the calculated stress by using the finite element （FE） code ANSYS. Fatigue reliability analysis of the welded shell is performed by using the Monte Carlo simulation method. The failure probability curve of the example kiln is significantly useful to determine the repair schedule of shell cracks.
文摘Uranium enrichment determination by non-destructive assay is an important method in authenticating the nuclear warhead or uranium component in deep nuclear reduction verifications.In this paper,the feasibility of applying the high-energy photon interrogation to determine the uranium enrichment is studied.Simplified models are presented which were simulated by particle Monte Carlo transport code.The results indicate that the relation curves of the released neutrons and the enrichment of uranium objects are almost linear.For a uranium object of a given shape,the uranium enrichment can be obtained with the relation curves,which could be got in advance by calibration experiments or simulations.
基金the National Natural Science Foundation of China (11235011)the National Basic Research Program of China (2015CB856701)CAS Center for Excellence in Particle Physics (CCEPP)
文摘The charged lepton flavor violation process is a clean and sensitive probe of new physics beyond the Standard Model. A sensitivity study is performed to the process τ^-→γμ^- based on a 3 fb^(-1) inclusive Monte Carlo sample of e^+e^- collisions at a center-of-mass energy of4.26 or 4.6 Ge V, in the framework of the BESIII software system. The 90 % confidence level upper limits on B(τ^-→γμ^-) are estimated assuming no signal is produced. We also obtain the sensitivity on B(τ^-→γμ^-) as a function of the integrated luminosity, to serve as a reference for the HIEPA being proposed in China. It is found that 6.34 ab^(-1) are needed to reach the current best upper limit of 4:4 10^(-8) and about 2510 ab^(-1) are needed to reach a sensitivity of 10^(-9) if the detector design is similar to that of BESIII.
