A physical value mapping （PVM） algorithm based on finite element mesh from the stamped part in stamping process to the product is presented, In order to improve the efficiency of the PVM algorithm, a search way from...A physical value mapping （PVM） algorithm based on finite element mesh from the stamped part in stamping process to the product is presented, In order to improve the efficiency of the PVM algorithm, a search way from the mesh of the product to the mesh of the stamped part will be adopted. At the same time, the search process is divided into two steps： entire search （ES） and local search （LS）, which improve the searching efficiency. The searching area is enlarged to avoid missing projection elements in ES process. An arc-length method is introduced in LS process. The validity is confirmed by the results of the complex industry-forming product.展开更多
Mapping mesh generation is widely applied in pre-processes of Finite Element Method （FEM）. In this study, the basic 3D mapping equations by Lagrange interpolating function are founded. Based these equations, a mappi...Mapping mesh generation is widely applied in pre-processes of Finite Element Method （FEM）. In this study, the basic 3D mapping equations by Lagrange interpolating function are founded. Based these equations, a mapping pattern library, which maps essential configurations e.g. line, circle, rotary body, sphere etc. to hexahedral FEM mesh, has been built. Then available FEM mesh will be generated by clipping and assembling the mapped essential objects. Study case illustrates that the proposed method is simple and efficient to generate valid FEM mesh for complex 3D engineering structure.展开更多
3D reconstruction of environment and weld workpiece can provide geometrical model for telerobotic welding and improve its intelligence. A novel framework of spacetime stereo is employed to overcome the lack of texture...3D reconstruction of environment and weld workpiece can provide geometrical model for telerobotic welding and improve its intelligence. A novel framework of spacetime stereo is employed to overcome the lack of texture of the weld workpiece and obtain subpixel disparity map of the scene. Anisotropic diffusion is adopted to smooth the original subpixel disparity map in order to reduce the noise while preserving the depth discontinuity. A simple algorithm of generation triangle mesh surface from the disparity map of the spucetime stereo is presented. The experimental results of real weld scenes are shown.展开更多
Based on the semi-quantitative approach, four environmental factors of sites (i.e. bedrock lithology, soil type, land use, and rainfall) were categorized, weighted and combined to determine and assess the relative sen...Based on the semi-quantitative approach, four environmental factors of sites (i.e. bedrock lithology, soil type, land use, and rainfall) were categorized, weighted and combined to determine and assess the relative sensitivity of the terrestrial ecosystems to acidic deposition in Fujian Province. Then the factors have been digitized and combined to assign an overall value for each mesh square (16.77 km×18.39 km) by using the geographic information system (GIS) The results indicated that the most sensitive area in Fujian was mainly located in the southeast, and the least: ensitive area was distributed sporadically in the east along the coast. Due to slow weathering rate of siliceous rocks, acid to weakly acid reactions of the soils, along with the greater percent of coniferous forests, more than 80 percent of the total area exhibits higher sensitivity classes (4–7).展开更多
针对三维微波器件优化中粗模型构建复杂、响应不连续以及优化效率低的问题,综述了近年来多策略协同加速的网格空间映射(mesh space mapping, MSM)技术的发展思路。现有研究普遍以粗网格有限元模型为基础,通过三类关键策略提升粗模型构...针对三维微波器件优化中粗模型构建复杂、响应不连续以及优化效率低的问题,综述了近年来多策略协同加速的网格空间映射(mesh space mapping, MSM)技术的发展思路。现有研究普遍以粗网格有限元模型为基础,通过三类关键策略提升粗模型构建效率:首先,利用结构锐化技术对圆角、螺钉等复杂边界进行近似简化,以降低网格数量与几何建模复杂度;其次,采用径向基函数网格变形方法,使粗模型在几何参数扰动下保持响应连续性与可导性;最后,结合灵敏度分析进行参数筛选,提取粗细模型之间的主要关联变量,从而压缩映射维度并减少训练样本量。基于上述策略体系形成的“锐化-变形-筛选”一体化粗模型构建框架,已在四阶调谐腔体滤波器优化等典型案例中得到应用,展示了其在保持优化精度前提下降低优化成本的潜力。该综述总结了不同策略在多调谐结构、高维参数空间以及响应离散性强等问题场景中的适用性,为构建自动化、低成本的电磁优化系统提供了方法参考与发展方向。展开更多
The fluid–structure interaction and aerodynamic shape optimization usually involve the moving or deforming boundaries, thus the dynamic mesh techniques are the key techniques to cope with such deformation. A novel dy...The fluid–structure interaction and aerodynamic shape optimization usually involve the moving or deforming boundaries, thus the dynamic mesh techniques are the key techniques to cope with such deformation. A novel dynamic mesh method was developed based on the Delaunay graph in this paper. According to the Delaunay graph, the mesh points were divided into groups. In each group, a factor ranging from 0 to 1 was calculated based on the area/volume ratio. By introducing a proper function for this factor, this method can control the mesh quality with high efficiency. Several test cases were compared with other dynamic mesh methods regarding mesh quality and CPU time, such as radial basis function method and Delaunay graph mapping method.展开更多
A novel VOF-type volume-tracking method for two-dimensional free-surface flows based on the unstructured triangular mesh is presented. Owing to the inherent merit of the unstructured triangular mesh in fitting curved ...A novel VOF-type volume-tracking method for two-dimensional free-surface flows based on the unstructured triangular mesh is presented. Owing to the inherent merit of the unstructured triangular mesh in fitting curved boundaries, this method can handle the free-surface problems with complex geometries accurately and directly, without introducing any complicated boundary treatment or artificial diffusion. The method solves the volume transport equation geometrically through the Modified Lagrangian-Eulerian Re-map （MLER） method, which is applied to advective fluid volumes. Moreover, the PLIC method is adopted to give a second-order reconstructed interface approximation. To validate this method, two advection tests were performed for the establishment of the accuracy and convergence rate of the solutions. Numerical results for these complex tests provide convincing evidence for the excellent solution quality and fidelity of the method.展开更多
基金This project is supported by National Natural Science Foundation ofChina(No.l9832020) and National Outstanding Youth Science Foundation ofChina(No.10125208).
文摘A physical value mapping （PVM） algorithm based on finite element mesh from the stamped part in stamping process to the product is presented, In order to improve the efficiency of the PVM algorithm, a search way from the mesh of the product to the mesh of the stamped part will be adopted. At the same time, the search process is divided into two steps： entire search （ES） and local search （LS）, which improve the searching efficiency. The searching area is enlarged to avoid missing projection elements in ES process. An arc-length method is introduced in LS process. The validity is confirmed by the results of the complex industry-forming product.
基金Supported by the National Natural Science Foundation of China (A10102006)
文摘Mapping mesh generation is widely applied in pre-processes of Finite Element Method （FEM）. In this study, the basic 3D mapping equations by Lagrange interpolating function are founded. Based these equations, a mapping pattern library, which maps essential configurations e.g. line, circle, rotary body, sphere etc. to hexahedral FEM mesh, has been built. Then available FEM mesh will be generated by clipping and assembling the mapped essential objects. Study case illustrates that the proposed method is simple and efficient to generate valid FEM mesh for complex 3D engineering structure.
文摘3D reconstruction of environment and weld workpiece can provide geometrical model for telerobotic welding and improve its intelligence. A novel framework of spacetime stereo is employed to overcome the lack of texture of the weld workpiece and obtain subpixel disparity map of the scene. Anisotropic diffusion is adopted to smooth the original subpixel disparity map in order to reduce the noise while preserving the depth discontinuity. A simple algorithm of generation triangle mesh surface from the disparity map of the spucetime stereo is presented. The experimental results of real weld scenes are shown.
文摘Based on the semi-quantitative approach, four environmental factors of sites (i.e. bedrock lithology, soil type, land use, and rainfall) were categorized, weighted and combined to determine and assess the relative sensitivity of the terrestrial ecosystems to acidic deposition in Fujian Province. Then the factors have been digitized and combined to assign an overall value for each mesh square (16.77 km×18.39 km) by using the geographic information system (GIS) The results indicated that the most sensitive area in Fujian was mainly located in the southeast, and the least: ensitive area was distributed sporadically in the east along the coast. Due to slow weathering rate of siliceous rocks, acid to weakly acid reactions of the soils, along with the greater percent of coniferous forests, more than 80 percent of the total area exhibits higher sensitivity classes (4–7).
文摘针对三维微波器件优化中粗模型构建复杂、响应不连续以及优化效率低的问题,综述了近年来多策略协同加速的网格空间映射(mesh space mapping, MSM)技术的发展思路。现有研究普遍以粗网格有限元模型为基础,通过三类关键策略提升粗模型构建效率:首先,利用结构锐化技术对圆角、螺钉等复杂边界进行近似简化,以降低网格数量与几何建模复杂度;其次,采用径向基函数网格变形方法,使粗模型在几何参数扰动下保持响应连续性与可导性;最后,结合灵敏度分析进行参数筛选,提取粗细模型之间的主要关联变量,从而压缩映射维度并减少训练样本量。基于上述策略体系形成的“锐化-变形-筛选”一体化粗模型构建框架,已在四阶调谐腔体滤波器优化等典型案例中得到应用,展示了其在保持优化精度前提下降低优化成本的潜力。该综述总结了不同策略在多调谐结构、高维参数空间以及响应离散性强等问题场景中的适用性,为构建自动化、低成本的电磁优化系统提供了方法参考与发展方向。
基金partially funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions of ChinaNational Natural Science Foundation of China (No. 11432007)Natural Science Foundation of Jiangsu Province of China (No. BK20140805)
文摘The fluid–structure interaction and aerodynamic shape optimization usually involve the moving or deforming boundaries, thus the dynamic mesh techniques are the key techniques to cope with such deformation. A novel dynamic mesh method was developed based on the Delaunay graph in this paper. According to the Delaunay graph, the mesh points were divided into groups. In each group, a factor ranging from 0 to 1 was calculated based on the area/volume ratio. By introducing a proper function for this factor, this method can control the mesh quality with high efficiency. Several test cases were compared with other dynamic mesh methods regarding mesh quality and CPU time, such as radial basis function method and Delaunay graph mapping method.
文摘A novel VOF-type volume-tracking method for two-dimensional free-surface flows based on the unstructured triangular mesh is presented. Owing to the inherent merit of the unstructured triangular mesh in fitting curved boundaries, this method can handle the free-surface problems with complex geometries accurately and directly, without introducing any complicated boundary treatment or artificial diffusion. The method solves the volume transport equation geometrically through the Modified Lagrangian-Eulerian Re-map （MLER） method, which is applied to advective fluid volumes. Moreover, the PLIC method is adopted to give a second-order reconstructed interface approximation. To validate this method, two advection tests were performed for the establishment of the accuracy and convergence rate of the solutions. Numerical results for these complex tests provide convincing evidence for the excellent solution quality and fidelity of the method.
