常规基于图像的绘制方法要求多幅图像作为输入或事先已知场景的三维信息才能生成新的图像.而TIP(tour into the picture)技术仅需一幅场景图像便可以生成新的视图,实现三维场景的虚拟漫游.详细介绍和实现了基于TIP的交互建模与漫游,用...常规基于图像的绘制方法要求多幅图像作为输入或事先已知场景的三维信息才能生成新的图像.而TIP(tour into the picture)技术仅需一幅场景图像便可以生成新的视图,实现三维场景的虚拟漫游.详细介绍和实现了基于TIP的交互建模与漫游,用户可以根据自己对图像的理解,利用鼠标任意设置场景关键点以恢复其三维模型,实现交互式的真实感漫游.展开更多
The vertical stability of a magnetic tip over a superconducting material is investigated by using the critical state and the frozen image models. The analytical expressions of the stiffness and the vibration frequency...The vertical stability of a magnetic tip over a superconducting material is investigated by using the critical state and the frozen image models. The analytical expressions of the stiffness and the vibration frequency about the equilibrium position are derived in term of the geometrical parameters of the magnet/superconductor system. It is found that the stability of the system depends on the shape of the superconductor as well as its thickness.展开更多
The uniformity of flow distribution of aluminum melt in tip cavity is a precondition to decide whether or not thin-gauge high-speed casting can be accomplished smoothly. The laws of aluminum melt flow and heat transfe...The uniformity of flow distribution of aluminum melt in tip cavity is a precondition to decide whether or not thin-gauge high-speed casting can be accomplished smoothly. The laws of aluminum melt flow and heat transfer in tip cavity can be found out through numerical simulation, which gives theoretical basis for solving the problem of the flow distribution of melt in tip cavity. A mathematical model with a low Reynolds number k—ε model for turbulence flow and heat transfer of aluminum melt in tip cavity was developed. The finite difference method was used to calculate the flow field and temperature field of aluminum melt in tip cavity. The phenomena and characteristics of turbulence flow and heat transfer were analyzed, including the characteristics of temperature distribution of turbulence similar to that of laminar flow. The simulation results are in good agreement with the experimental results for flow velocities and temperature at the exit of tip, which verifies the validity of the simulation results.展开更多
This paper presents a comprehensive derivation of fracture process zone size which closely parallels similar work in fracture of metals and anisotropic solid, but is adapted to conrete. Some nonlinear mechanics models...This paper presents a comprehensive derivation of fracture process zone size which closely parallels similar work in fracture of metals and anisotropic solid, but is adapted to conrete. Some nonlinear mechanics models of concrete materials will be discussed by using uniaxial stress assumptions. For uniaxial stress assumption, energy model and fracture model will be presented for nonlinear softening models. Finally, we make a comparison with those models.展开更多
The penetration of a model pile through sand was investigated via a numerical analysis. Data from nine triaxial compression tests on dense specimens at different stress levels was generalized and used to create an emp...The penetration of a model pile through sand was investigated via a numerical analysis. Data from nine triaxial compression tests on dense specimens at different stress levels was generalized and used to create an empirical non-linear plastic hardening stress-strain relation for use in the analysis. As the computer program used is capable of large displacement analyses in radial symmetry, we expected that the analysis would easily reproduce the tip resistance penetration profile of the model pile in sand of known density and stress. However, initial attempts led to over-prediction. Successful analyses required both successive reformations of the mesh and the complete elimination of the dilatant peak in soil strength, which is naturally eliminated under large confining stress directly beneath the advancing tip, and that soil in the far-field had strained insufficiently to reach peak strength. Thus, the soil around the shaft must have been sheared to a critical state as it flowed past the tip. The hypothesis that the resistance to displacement piles in sand is mainly a function of the deformability of the sand was again proven, and the use of peak strength in the traditional bearing capacity formulae was found to be inappropriate. Independent investigation in this direction is needed to quantify the hypothesis.展开更多
A three-nested-deformation model is proposed to describe crack-tip fields in rubber-like materials with large deformation. The model is inspired by the distribution of the measured in-plane and out-of-plane deformatio...A three-nested-deformation model is proposed to describe crack-tip fields in rubber-like materials with large deformation. The model is inspired by the distribution of the measured in-plane and out-of-plane deformation. The in- plane displacement of crack-tip fields under both Mode 1 and mixed-mode （Mode I-II） fracture conditions is measured by using the digital Moir6 method. The deformation character- istics and experimental sector division mode are investigated by comparing the measured displacement fields under differ- ent fracture modes. The out-of-plane displacement field near the crack tip is measured using the three-dimensional digital speckle correlation method.展开更多
文摘常规基于图像的绘制方法要求多幅图像作为输入或事先已知场景的三维信息才能生成新的图像.而TIP(tour into the picture)技术仅需一幅场景图像便可以生成新的视图,实现三维场景的虚拟漫游.详细介绍和实现了基于TIP的交互建模与漫游,用户可以根据自己对图像的理解,利用鼠标任意设置场景关键点以恢复其三维模型,实现交互式的真实感漫游.
文摘The vertical stability of a magnetic tip over a superconducting material is investigated by using the critical state and the frozen image models. The analytical expressions of the stiffness and the vibration frequency about the equilibrium position are derived in term of the geometrical parameters of the magnet/superconductor system. It is found that the stability of the system depends on the shape of the superconductor as well as its thickness.
文摘The uniformity of flow distribution of aluminum melt in tip cavity is a precondition to decide whether or not thin-gauge high-speed casting can be accomplished smoothly. The laws of aluminum melt flow and heat transfer in tip cavity can be found out through numerical simulation, which gives theoretical basis for solving the problem of the flow distribution of melt in tip cavity. A mathematical model with a low Reynolds number k—ε model for turbulence flow and heat transfer of aluminum melt in tip cavity was developed. The finite difference method was used to calculate the flow field and temperature field of aluminum melt in tip cavity. The phenomena and characteristics of turbulence flow and heat transfer were analyzed, including the characteristics of temperature distribution of turbulence similar to that of laminar flow. The simulation results are in good agreement with the experimental results for flow velocities and temperature at the exit of tip, which verifies the validity of the simulation results.
文摘This paper presents a comprehensive derivation of fracture process zone size which closely parallels similar work in fracture of metals and anisotropic solid, but is adapted to conrete. Some nonlinear mechanics models of concrete materials will be discussed by using uniaxial stress assumptions. For uniaxial stress assumption, energy model and fracture model will be presented for nonlinear softening models. Finally, we make a comparison with those models.
文摘The penetration of a model pile through sand was investigated via a numerical analysis. Data from nine triaxial compression tests on dense specimens at different stress levels was generalized and used to create an empirical non-linear plastic hardening stress-strain relation for use in the analysis. As the computer program used is capable of large displacement analyses in radial symmetry, we expected that the analysis would easily reproduce the tip resistance penetration profile of the model pile in sand of known density and stress. However, initial attempts led to over-prediction. Successful analyses required both successive reformations of the mesh and the complete elimination of the dilatant peak in soil strength, which is naturally eliminated under large confining stress directly beneath the advancing tip, and that soil in the far-field had strained insufficiently to reach peak strength. Thus, the soil around the shaft must have been sheared to a critical state as it flowed past the tip. The hypothesis that the resistance to displacement piles in sand is mainly a function of the deformability of the sand was again proven, and the use of peak strength in the traditional bearing capacity formulae was found to be inappropriate. Independent investigation in this direction is needed to quantify the hypothesis.
基金supported by the National Natural Science Foundation of China (10732080 and 11102134)
文摘A three-nested-deformation model is proposed to describe crack-tip fields in rubber-like materials with large deformation. The model is inspired by the distribution of the measured in-plane and out-of-plane deformation. The in- plane displacement of crack-tip fields under both Mode 1 and mixed-mode （Mode I-II） fracture conditions is measured by using the digital Moir6 method. The deformation character- istics and experimental sector division mode are investigated by comparing the measured displacement fields under differ- ent fracture modes. The out-of-plane displacement field near the crack tip is measured using the three-dimensional digital speckle correlation method.
