A mathematical program is proposed for the highly nonlinear problem involving frictional contact. A program-pattern using the fast multipole boundary element method (FM- BEM) is given for 3-D elastic contact with fric...A mathematical program is proposed for the highly nonlinear problem involving frictional contact. A program-pattern using the fast multipole boundary element method (FM- BEM) is given for 3-D elastic contact with friction to replace the Monte Carlo method. A new optimized generalized minimal residual (GMRES) algorithm is presented. Numerical examples demonstrate the validity of the program-pattern optimization model for node-to-surface contact with friction. The GMRES algorithm greatly improves the computational efciency.展开更多
本文提出了一种可靠的图像去噪算法,基于观察图像是期望图像叠加了不规则噪声的假设,用有限高斯混合分布(FNM)描述期望图像分解小波系数(WC)的先验分布,用隐马尔可夫模型(HMM)描述同一方向不同分解级之间的小波系数的依赖关系,采用Baye...本文提出了一种可靠的图像去噪算法,基于观察图像是期望图像叠加了不规则噪声的假设,用有限高斯混合分布(FNM)描述期望图像分解小波系数(WC)的先验分布,用隐马尔可夫模型(HMM)描述同一方向不同分解级之间的小波系数的依赖关系,采用Bayes准则,根据期望图像的后验分布(以观测图像为条件)所对应的HMM模型的条件概率,用EM(expectation maximization)优化算法,获得MAP(maximization a posteriori)准则下的去噪图像。针对银基触头材料表面形貌去噪对几种算法作定性比较,并对去噪性能给出定量分析,仿真结果表明,此方法有效去除噪声的同时,能保留原始图像的细节信息。展开更多
A quasi-three-dimensional shell element model, which can beeffectively used to simulate the flanging and spring-backdeformation, is introduced into the independently developed CAEsoftware, KMAS, In this model, a doubl...A quasi-three-dimensional shell element model, which can beeffectively used to simulate the flanging and spring-backdeformation, is introduced into the independently developed CAEsoftware, KMAS, In this model, a double surface contact algorithm,which allows the gap between punch and die to change, and a spring-back treatment scheme based on finite element meshing are described.And then the flanging and spring-back deformations of the retractor'skickstand of a railcar made of stamped thick metal plate arenumerically simulated. The simulation results of flanging deformationare compared with those of international commercial software,PAM-STAMP, and experimental ones. Finally, a predicting scheme ofspring-back quantily for this problem is given.展开更多
This paper presents a new mathematical model for the highly nonlinear problem of frictional con- tact. A programming model, multipole boundary element method (BEM), was developed for 3-D elastic con- tact with frict...This paper presents a new mathematical model for the highly nonlinear problem of frictional con- tact. A programming model, multipole boundary element method (BEM), was developed for 3-D elastic con- tact with friction to replace the Monte Carlo method. A numerical example shows that the optimization pro- gramming model for the point-to-surface contact with friction and the fast optimization generalized minimal residual algorithm (GMRES(m)) significantly improve the analysis of such problems relative to the conven- tional BEM.展开更多
The analysis of 3-D elasto-plastic contact with friction is a highly nonlinear problem. The ele- ments in the contact and plastic zones should be refined to obtain accurate information about the real size, displacem...The analysis of 3-D elasto-plastic contact with friction is a highly nonlinear problem. The ele- ments in the contact and plastic zones should be refined to obtain accurate information about the real size, displacement, and traction in the contact zone. However, the increase in the number of degrees of freedom is limited when traditional boundary element method (BEM) is used with the larger memory size and long CPU time required for the solution procedure. This paper describes the additional mathematical friction model to the 3-D elastic multipole BEM to develop a 3-D elasto-plastic contact multipole BEM. Numerical tests show that with this new method, the needed computer memory size is only 2% of the traditional BEM model with friction, which erases large-scale computing with refined meshes and improves the computa- tional accuracy.展开更多
基金Project supported by the National Natural Science Foundation of China(No.50075075).
文摘A mathematical program is proposed for the highly nonlinear problem involving frictional contact. A program-pattern using the fast multipole boundary element method (FM- BEM) is given for 3-D elastic contact with friction to replace the Monte Carlo method. A new optimized generalized minimal residual (GMRES) algorithm is presented. Numerical examples demonstrate the validity of the program-pattern optimization model for node-to-surface contact with friction. The GMRES algorithm greatly improves the computational efciency.
文摘本文提出了一种可靠的图像去噪算法,基于观察图像是期望图像叠加了不规则噪声的假设,用有限高斯混合分布(FNM)描述期望图像分解小波系数(WC)的先验分布,用隐马尔可夫模型(HMM)描述同一方向不同分解级之间的小波系数的依赖关系,采用Bayes准则,根据期望图像的后验分布(以观测图像为条件)所对应的HMM模型的条件概率,用EM(expectation maximization)优化算法,获得MAP(maximization a posteriori)准则下的去噪图像。针对银基触头材料表面形貌去噪对几种算法作定性比较,并对去噪性能给出定量分析,仿真结果表明,此方法有效去除噪声的同时,能保留原始图像的细节信息。
基金the National Natural Science Foundation of China(No.19832020)the Ministry of Education of China.
文摘A quasi-three-dimensional shell element model, which can beeffectively used to simulate the flanging and spring-backdeformation, is introduced into the independently developed CAEsoftware, KMAS, In this model, a double surface contact algorithm,which allows the gap between punch and die to change, and a spring-back treatment scheme based on finite element meshing are described.And then the flanging and spring-back deformations of the retractor'skickstand of a railcar made of stamped thick metal plate arenumerically simulated. The simulation results of flanging deformationare compared with those of international commercial software,PAM-STAMP, and experimental ones. Finally, a predicting scheme ofspring-back quantily for this problem is given.
基金Supported by the National Natural Science Foundation of China(No. 50075075)
文摘This paper presents a new mathematical model for the highly nonlinear problem of frictional con- tact. A programming model, multipole boundary element method (BEM), was developed for 3-D elastic con- tact with friction to replace the Monte Carlo method. A numerical example shows that the optimization pro- gramming model for the point-to-surface contact with friction and the fast optimization generalized minimal residual algorithm (GMRES(m)) significantly improve the analysis of such problems relative to the conven- tional BEM.
基金Supported by the National Natural Science Foundation of China(No. 50075075)
文摘The analysis of 3-D elasto-plastic contact with friction is a highly nonlinear problem. The ele- ments in the contact and plastic zones should be refined to obtain accurate information about the real size, displacement, and traction in the contact zone. However, the increase in the number of degrees of freedom is limited when traditional boundary element method (BEM) is used with the larger memory size and long CPU time required for the solution procedure. This paper describes the additional mathematical friction model to the 3-D elastic multipole BEM to develop a 3-D elasto-plastic contact multipole BEM. Numerical tests show that with this new method, the needed computer memory size is only 2% of the traditional BEM model with friction, which erases large-scale computing with refined meshes and improves the computa- tional accuracy.
