A developed stereo particle image velocimetry(stereo-PIV) system was proposed to measure three-dimensional(3D) soil deformation around a laterally loaded pile in sand.The stereo-PIV technique extended 2D measurement t...A developed stereo particle image velocimetry(stereo-PIV) system was proposed to measure three-dimensional(3D) soil deformation around a laterally loaded pile in sand.The stereo-PIV technique extended 2D measurement to 3D based on a binocular vision model,where two cameras with a well geometrical setting were utilized to image the same object simultaneously.This system utilized two open software packages and some simple programs in MATLAB,which can easily be adjusted to meet user needs at a low cost.The failure planes form an angle with the horizontal line,which are measured at 27°-29°,approximately three-fourths of the frictional angle of soil.The edge of the strain wedge formed in front of the pile is an arc,which is slightly different from the straight line reported in the literature.The active and passive influence zones are about twice and six times of the diameter of the pile,respectively.The test demonstrates the good performance and feasibility of this stereo-PIV system for more advanced geotechnical testing.展开更多
The transverse permeability of unidirectional fiber tows is calculated using homogenization method.Each fiber tow consisting of 21 filaments is arranged in uniform square packing.Stokes governing equation is analogize...The transverse permeability of unidirectional fiber tows is calculated using homogenization method.Each fiber tow consisting of 21 filaments is arranged in uniform square packing.Stokes governing equation is analogized with Lame equation used in the linear elasticity problem and is solved by the finite element code ANSYS.The prediction for transverse permeability of unidirectional fiber obtained by the homogenization approach is compared with other analytical methods.The result shows a good agreement with Kozeny-Carman equation and Gebart square packing model.A model for nonuniform fiber distribution and measurement technology are proposed.It can be found that the experimental result is in excellent agreement with predicted permeability in the nonuniform distribution model.展开更多
Fission-Track Dating (FTD) has been developed as a useful technique for geological studies. Parent elements are measured by counting 235 U tracks induced by thermal neutrons. If insufficient thermalization occurs, fis...Fission-Track Dating (FTD) has been developed as a useful technique for geological studies. Parent elements are measured by counting 235 U tracks induced by thermal neutrons. If insufficient thermalization occurs, fission of 238 U and 232 Th will be induced, and further measurement error will be introduced. Therefore, whether the neutrons are well thermalized or not will affect the FTD results. Due to requirement of safe operation, the 101 reactor was terminated in 2007. By using the 492 reactor as the new thermal neutron reactor, our present paper will attempt to study the feasibility and the potential influence on FTD. By irradiating monitor glass SRM612 and CN5 in pairs, we will study the thermalization situation of the 492 reactor. Irradiated data show that thermal neutrons are not evenly distributed either in horizontal or in vertical dimension. Especially, horizontal heterogeneity is obvious. But we discovered that proper irradiation position in the reactor can meet the requirement of FTD. Under the current irradiation condition, we calculated and assessed the insufficient thermalization effects on determining fission-track ages. We found that the difference between the 232 Th/ 238 U ratios of samples and standards is the main factor to the experiment results. The results will not be affected if the 232 Th/ 238 U value of samples is equal to the standard samples. However, if the 232 Th/ 238 U ratio is larger than that of the standards, the results will be smaller than actual ages. Comparatively, the ages will be more than expected if the 232 Th/ 238 U ratio is less. Therefore, to reduce the irradiation error, we suggest either locating the position of irradiation strictly, or minimizing the influence of lateral heterogeneity by reducing the amount of each sample package. Additionally, accuracy of the experimental results can be improved by increasing standard samples to adjust ζ value and using the monitor of standard glass SRM612 and CN5 together.展开更多
In this work, the theoretical model of FBG when it is affected by double external variables (temperature and transverse pressure) and triple external variables (temperature, axial strain and transverse pressure) is de...In this work, the theoretical model of FBG when it is affected by double external variables (temperature and transverse pressure) and triple external variables (temperature, axial strain and transverse pressure) is deduced, respectively. The simulated results show that the properties of cross sensitivity would change in a certain regulation with the external effects and fiber parameters. At the same time, some valuable suggestions about how to improve the measurement accuracy are put forward as well.展开更多
基金Project(104244) supported by the Natural Sciences and Engineering Research Council of Canada
文摘A developed stereo particle image velocimetry(stereo-PIV) system was proposed to measure three-dimensional(3D) soil deformation around a laterally loaded pile in sand.The stereo-PIV technique extended 2D measurement to 3D based on a binocular vision model,where two cameras with a well geometrical setting were utilized to image the same object simultaneously.This system utilized two open software packages and some simple programs in MATLAB,which can easily be adjusted to meet user needs at a low cost.The failure planes form an angle with the horizontal line,which are measured at 27°-29°,approximately three-fourths of the frictional angle of soil.The edge of the strain wedge formed in front of the pile is an arc,which is slightly different from the straight line reported in the literature.The active and passive influence zones are about twice and six times of the diameter of the pile,respectively.The test demonstrates the good performance and feasibility of this stereo-PIV system for more advanced geotechnical testing.
基金Tianjin Natural Science Foundation, China (No.06YFJ MJC03100,013604311)
文摘The transverse permeability of unidirectional fiber tows is calculated using homogenization method.Each fiber tow consisting of 21 filaments is arranged in uniform square packing.Stokes governing equation is analogized with Lame equation used in the linear elasticity problem and is solved by the finite element code ANSYS.The prediction for transverse permeability of unidirectional fiber obtained by the homogenization approach is compared with other analytical methods.The result shows a good agreement with Kozeny-Carman equation and Gebart square packing model.A model for nonuniform fiber distribution and measurement technology are proposed.It can be found that the experimental result is in excellent agreement with predicted permeability in the nonuniform distribution model.
基金supported by State Key Laboratory of Earthquake Dynamics (Grant No.LED2009A05)National Natural Science Foundation of China (Grant No.41030317)
文摘Fission-Track Dating (FTD) has been developed as a useful technique for geological studies. Parent elements are measured by counting 235 U tracks induced by thermal neutrons. If insufficient thermalization occurs, fission of 238 U and 232 Th will be induced, and further measurement error will be introduced. Therefore, whether the neutrons are well thermalized or not will affect the FTD results. Due to requirement of safe operation, the 101 reactor was terminated in 2007. By using the 492 reactor as the new thermal neutron reactor, our present paper will attempt to study the feasibility and the potential influence on FTD. By irradiating monitor glass SRM612 and CN5 in pairs, we will study the thermalization situation of the 492 reactor. Irradiated data show that thermal neutrons are not evenly distributed either in horizontal or in vertical dimension. Especially, horizontal heterogeneity is obvious. But we discovered that proper irradiation position in the reactor can meet the requirement of FTD. Under the current irradiation condition, we calculated and assessed the insufficient thermalization effects on determining fission-track ages. We found that the difference between the 232 Th/ 238 U ratios of samples and standards is the main factor to the experiment results. The results will not be affected if the 232 Th/ 238 U value of samples is equal to the standard samples. However, if the 232 Th/ 238 U ratio is larger than that of the standards, the results will be smaller than actual ages. Comparatively, the ages will be more than expected if the 232 Th/ 238 U ratio is less. Therefore, to reduce the irradiation error, we suggest either locating the position of irradiation strictly, or minimizing the influence of lateral heterogeneity by reducing the amount of each sample package. Additionally, accuracy of the experimental results can be improved by increasing standard samples to adjust ζ value and using the monitor of standard glass SRM612 and CN5 together.
基金supported by the National Natural Science Foundation of China (No.50876120)the Natural Science Foundation Project of Chongqing, China (No.2010BB2298)
文摘In this work, the theoretical model of FBG when it is affected by double external variables (temperature and transverse pressure) and triple external variables (temperature, axial strain and transverse pressure) is deduced, respectively. The simulated results show that the properties of cross sensitivity would change in a certain regulation with the external effects and fiber parameters. At the same time, some valuable suggestions about how to improve the measurement accuracy are put forward as well.
