A mathematical model, which not only fully couples fluid flow and solid skeleton deformation in unsaturated porous elastic media but also considers deformable diaphragm walls, is formulated in axially symmetric cylind...A mathematical model, which not only fully couples fluid flow and solid skeleton deformation in unsaturated porous elastic media but also considers deformable diaphragm walls, is formulated in axially symmetric cylindrical coordinates for drawdown and land deformation. Based on this model, pumping-recovery tests in various conditions are numerically simulated to reveal the effects of elastic modulus of soil E and initial saturated hydraulic conductivity K_(sat0) on hydraulic head and land deformation. The heterogeneity with respect to E and K_(sat0) is separately taken into account. Large elastic modulus of soil contributes to both dewatering process and deformation control. Either large or small initial saturated hydraulic conductivity may cause relatively high groundwater table, while the larger one leads to smaller displacements.展开更多
This paper presents the results of numerical simulations carried out to confirm the influence of former mining activities on deformation of the mining terrain.The assessment of deformation changes was carried out with...This paper presents the results of numerical simulations carried out to confirm the influence of former mining activities on deformation of the mining terrain.The assessment of deformation changes was carried out with the use of FLAC3 D program based on the finite difference method.Numerical calculations were carried out for the example of actual mining operations in seams 703/1-2 and 707/2 of‘‘Marcel"Coal Mine.Taking into account the influence of the model’s plastic features and the so-called activation of a higher occurring seam in conducted simulations enabled obtaining a very good description of the measured subsidence.Based on the results one may state that numerical model can be used to assess the influence of former mining activities and the direction of conducted exploitation on deformations of the mining terrain.These factors are not recognized by geometric-integral theories commonly used for predicting the influence of mining operations on the surface.The results presented in this paper confirm that the applied method of simulating the phenomenon of reactivation of post-mining goafs is correct.展开更多
A systematic, accurate and robust evaluating method for fine pitch printed circuit board （PCB） positioning assessment in testing fixture is developed. Targeting reliability of bed-of-nails tester is successfully eva...A systematic, accurate and robust evaluating method for fine pitch printed circuit board （PCB） positioning assessment in testing fixture is developed. Targeting reliability of bed-of-nails tester is successfully evaluated by the 2D pattern transform. Probe offset vector with its Weibull and Gaussian distribution estimates are obtained for further investigation about the causes of misalignment on the basis of a batch tests for same kind of PCBs.展开更多
基金the National Natural Science Foundation of China(Nos.41330633 and 41372286)the Foundation of State Key Laboratory of Ocean Engineering(No.GKZD010059)
文摘A mathematical model, which not only fully couples fluid flow and solid skeleton deformation in unsaturated porous elastic media but also considers deformable diaphragm walls, is formulated in axially symmetric cylindrical coordinates for drawdown and land deformation. Based on this model, pumping-recovery tests in various conditions are numerically simulated to reveal the effects of elastic modulus of soil E and initial saturated hydraulic conductivity K_(sat0) on hydraulic head and land deformation. The heterogeneity with respect to E and K_(sat0) is separately taken into account. Large elastic modulus of soil contributes to both dewatering process and deformation control. Either large or small initial saturated hydraulic conductivity may cause relatively high groundwater table, while the larger one leads to smaller displacements.
文摘This paper presents the results of numerical simulations carried out to confirm the influence of former mining activities on deformation of the mining terrain.The assessment of deformation changes was carried out with the use of FLAC3 D program based on the finite difference method.Numerical calculations were carried out for the example of actual mining operations in seams 703/1-2 and 707/2 of‘‘Marcel"Coal Mine.Taking into account the influence of the model’s plastic features and the so-called activation of a higher occurring seam in conducted simulations enabled obtaining a very good description of the measured subsidence.Based on the results one may state that numerical model can be used to assess the influence of former mining activities and the direction of conducted exploitation on deformations of the mining terrain.These factors are not recognized by geometric-integral theories commonly used for predicting the influence of mining operations on the surface.The results presented in this paper confirm that the applied method of simulating the phenomenon of reactivation of post-mining goafs is correct.
基金This project is supported by US Pennsylvania Dept. of Community & Economic Development(No.20-906-0015)National Natural Science Foundation of China(No.50390064, No.50575230)National Basic Research Program of China(973 Program, No.2003CB716202).
文摘A systematic, accurate and robust evaluating method for fine pitch printed circuit board （PCB） positioning assessment in testing fixture is developed. Targeting reliability of bed-of-nails tester is successfully evaluated by the 2D pattern transform. Probe offset vector with its Weibull and Gaussian distribution estimates are obtained for further investigation about the causes of misalignment on the basis of a batch tests for same kind of PCBs.
