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Preliminary study on CAD-based method of characteristics for neutron transport calculation

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Chinese Physics C 2014年第5期38卷 114-120页

作者：陈珍平郑华庆孙光耀宋婧郝丽娟胡丽琴吴宜灿 University of Science and Technology of China Institute of Nuclear Energy Safety Technology Chinese Academy of Sciences

Our new method makes use of a CAD-based automatic modeling tool, MCAM, for geometry modeling and ray tracing of particle transport in method of characteristics （MOC）. It was found that it could considerably enhance the capability of MOC to deal with more complicated models for neutron transport calculation. In our study, the diamond-difference scheme was applied to MOC to reduce the spatial discretization errors of the fiat flux approximation. Based on MCAM and MOC, a new 2D MOC code was developed and integrated into the SuperMC system, which is a Super Multi-function Computational system for neutronics and radiation simulation. The numerical results demonstrated the feasibility and effectiveness of the new method for neutron transport calculation in MOC.

关键词： method of characteristics neutron transport calculation CAD geometry modeling

Interactive point cloud blending by drag-and-drop

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第10期8卷 1633-1641页

作者： ZOU Wan-hong?1, DING Zhan1, YE Xiu-zi1, CHEN Zhi-yang2 (1State Key Lab. of CAD and CG, School of Computer Science and Technology, Zhejiang University, Hangzhou 310027, China) (2Software College, Zhejiang University of Technology, Hangzhou 310014, China) State Key Lab. of CAD CG School of Computer Science Technology Zhejiang University Hangzhou 310027 China Software College Zhejiang University of Technology Hangzhou 310014 China

With the rapid development of 3D digital photography and 3D digital scanning devices, massive amount of point samples can be generated in acquisition of complex, real-world objects, and thus create an urgent need for advanced point-based processing and editing. In this paper, we present an interactive method for blending point-based geometries by dragging-and- dropping one point-based model onto another model’s surface metaphor. We first calculate a blending region based on the polygon of interest when the user drags-and-drops the model. Radial basis function is used to construct an implicit surface which smoothly interpolates with the transition regions. Continuing the drag-and-drop operation will make the system recalculate the blending regions and reconstruct the transition regions. The drag-and-drop operation can be compound in a constructive solid geometry (CSG) manner to interactively construct a complex point-based model from multiple simple ones. Experimental results showed that our method generates good quality transition regions between two raw point clouds and can effectively reduce the rate of overlapping during the blending.

关键词： Drag-and-drop Point cloud model Interactive blending geometry modeling

Computer aided modeling and pore distribution of bionic porous bone structure

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Journal of Central South University 2012年第12期19卷 3492-3499页

作者：李虎杨建宇苏鹏程王宛山 School of Mechanical Engineering and Automation Northeastern University State Key Laboratory of Tunnel Boring Machine(Northern Heavy Industries Group)

Artificial bone with porous structure is crucial for tissue scaffold and clinic *** provides structure support for cells and guides tissues regeneration for final tissue structure.A computational aided process of porous bone modeling was developed which described the design and fabrication of tissue scaffolds by considering intricate architecture,porosity and pore *** simulate intricate bone structure,different constructive units were *** modeling process,bone contour was gotten from computed tomography(CT)images and was divided into two *** level was represented by relatively reconstructive *** size distribution was controlled by using mesh *** whole hexahedral mesh was reduced by unit structure,when a 3D mesh with various hexahedral elements was *** simulation results show that constructive structure of porous scaffold can meet the needs of clinic implants in accurate and controlled way.

关键词： tissue scaffold geometry modeling porous structure compute aided design optimal design clinic implants

Shape Modification by Beam Model in FEM

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Chinese Journal of Aeronautics 2010年第2期23卷 246-251页

作者：王志国王小平鲍益东周来水南京航空航天大学江苏省精密与微细制造技术重点实验室

Shape modification and deformation play an important role in the filed of geometry modeling, computer graphics, conceptual design and so on. A novel physically based shape modification approach is presented in this article, with beam model in finite element method （FEM）. By means of interactively creating a beam with circle cross section based on pre-defined local coordi- nate system, the primitive geometry model is embedded in the beam globally or locally. After imposing external loads, such as concentrated force or couple, on selected nodes, their displacement can be computed. Moreover, deflection, axial deformation and twist angle of beam model can also be interpolated using shape function matrix. As a result, object is modified as a part of beam. The proposed approach is linear, simple and fast, by which stretch, bending, taping and twist deformation can be accom- plished. Finally, some experimental results are given to demonstrate that the presented method is potentially useful in geometry modeling and shape design.

关键词： geometry modeling deformation finite element method stiffness matrix

An Approach to RCS Computation for Complex Targets

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Journal of Systems Engineering and Electronics 1997年第4期8卷 56-60页

作者： Zhao Weijiang & Wang Maoguang Xidian University, Xi’an 710071, P. R. China Xidian University Xi'an 710071 P. R. China

A practical approach for calculating the RCS (Radar Cross Section) of complex targets modeled with wire-grid-frame is presented. A way for generating a polyhedron model (facet-wedge model) with the wire-grid-frame dat... 详细信息

关键词： Radar cross section geometry modeling Complex target.

CT-based Individualized Medical Implant Design

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Journal of Donghua University(English Edition) 2003年第3期20卷 46-50页

作者：叶铭朱晓峰王成焘孙坚 School of Mechanical Engineering Shanghai Jiaotong University Shanghai 200030 Shanghai Second Medical University Shanghai 200025

Most implantation cases are implemented using implants selected from the available standard set, but in some cases, only those implants conforming to individual patient's skeletal morphology can serve the purpose. This paper proposes a new approach to design and fabricate custom-made exact-fit medical implants. With a real surgical case as the example,technical design details are presented; and three algorithms are given respectively for segmentation based on object features, triangular mesh defragmentation and mesh cutting.

关键词： 3D image segmentation geometry modeling Rapid prototyping Surgical simulation

Open Volumetric Mesh-An Efficient Data Structure for Tetrahedral and Hexahedral Meshes

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Computer Aided Drafting,Design and Manufacturing 2013年第3期23卷 23-27页

作者： XIAN Chu-hua LI Gui-qing GAO Shu-ming School of Computer Science and Engineering South China University of Technology State Key Lab. Of CAD & CG Zhejiang University

This work introduces a scalable and efficient topological structure for tetrahedral and hexahedral meshes. The design of the data structure aims at maximal flexibility and high performance. It provides a high scalability by using hierarchical representa-tions of topological elements. The proposed data structure is array-based, and it is a compact representation of the half-edge data structure for volume elements and half-face data structure for volumetric meshes. This guarantees constant access time to the neighbors of the topological elements. In addition, an open-source implementation named Open Volumetric Mesh （OVM） of the pro-posed data structure is written in C＋＋ using generic programming concepts.

关键词： tetrahedral mesh hexahedral mesh geometry modeling data structure generic programming