为了克服传统基于区域的图像分割方法对图像初始划分完全随机进而导致算法效率低下的缺点,本文提出了一种基于Delaunay划分并结合最大期望值(Expectation Maximization,EM)和最大边缘概率(Maximization of the Posterior Marginal,MPM)...为了克服传统基于区域的图像分割方法对图像初始划分完全随机进而导致算法效率低下的缺点,本文提出了一种基于Delaunay划分并结合最大期望值(Expectation Maximization,EM)和最大边缘概率(Maximization of the Posterior Marginal,MPM)算法的图像分割方法。该方法首先提取图像特征点,并把特征点集作为构建Delaunay三角网的基础点集。利用Delaunay三角网的构建将影像划分成众多彼此连接的超像素,并假设这些超像素内的像素灰度值服从同一独立的正态分布,基于此完成特征场模型的建立,再运用EM\MPM方法分别模拟特征场模型和分割影像。为了验证本文提出的算法能够有效地分割图像,分别对模拟图像和真实图像进行分割测试,并和经典的初始划分完全随机的超像素影像分割算法进行对比,测试结果定性和定量地表明了该方法的有效性和准确性。展开更多
基于区域和统计的SAR分割方法,提出一种结合Voronoi划分技术、最大期望值EM(Expectation Maximization)和最大边缘概率MPM(Maximization of the Posterior Marginal)算法的多视SAR图像分割方法。首先利用Voronoi划分将图像域划分成不同...基于区域和统计的SAR分割方法,提出一种结合Voronoi划分技术、最大期望值EM(Expectation Maximization)和最大边缘概率MPM(Maximization of the Posterior Marginal)算法的多视SAR图像分割方法。首先利用Voronoi划分将图像域划分成不同的子区域,而每个子区域可以被看成待分割同质区域的一个组成部分,并假设每个子区域内的像素满足同一独立的Gamma分布,从而建立多视SAR图像模型,并在贝叶斯理论架构下建立图像分割模型,然后结合EM/MPM算法进行图像分割和模型参数估计。该方法将基于像元的马尔可夫随机场(Markov Random Field,MRF)模型扩展到基于区域的MRF模型,并且能同时有效地获取模型参数估计和基于区域的SAR图像最优分割。采用本文算法,分别对RADARSAT-Ⅰ/ⅡSAR强度图像和合成SAR强度图像进行了分割实验,定性和定量的测试结果验证了本文方法的有效性、可靠性和准确性。展开更多
A new multi-mesh contact algorithm for three-dimensional material point method is presented. The contact algorithm faithfully recovers the opposite acting forces between colliding bodies. Collision procedures between ...A new multi-mesh contact algorithm for three-dimensional material point method is presented. The contact algorithm faithfully recovers the opposite acting forces between colliding bodies. Collision procedures between regular bodies and/or rigid bodies are treated within the same framework. Multi-value of momentum and mass are defined on every node to describe the contact/sliding/separation procedure. Both normal and tangential velocities of each particle at the contact surface are calculated in respective individual mesh. A Coulomb friction is applied to describe the sliding or slipping between the contacting bodies. The efficiency of the contact algorithm is linearly related to the number of the contacting bodies because the overlapped nodes are labeled by sweeping the material particles of all bodies when the nodal momentum and mass are formed at every time step. Numerical simulation shows that our contact algorithm possesses high accuracy and low numerical energy dissipation, which is very important for solving collision problems.展开更多
The combination of Morgenstern-Price Method （MPM） with Response Surface Method （RSM） improves the eonventional RSM by replacing Finite-Element Method （FEM） with MPM, which is a type of reliability analysis metho...The combination of Morgenstern-Price Method （MPM） with Response Surface Method （RSM） improves the eonventional RSM by replacing Finite-Element Method （FEM） with MPM, which is a type of reliability analysis method-RSM based on MPM, and makes the computing process simpler. The stability of the slope was re-evaluated by use of Monte Carlo method （MCM） and the result contrasted with the fore is the conclusion. The reliability analysis of the artificial slope in Donggang Power Station was carried on, and obtained the reliable charaeteristics, which provided basis for the project.展开更多
文摘为了克服传统基于区域的图像分割方法对图像初始划分完全随机进而导致算法效率低下的缺点,本文提出了一种基于Delaunay划分并结合最大期望值(Expectation Maximization,EM)和最大边缘概率(Maximization of the Posterior Marginal,MPM)算法的图像分割方法。该方法首先提取图像特征点,并把特征点集作为构建Delaunay三角网的基础点集。利用Delaunay三角网的构建将影像划分成众多彼此连接的超像素,并假设这些超像素内的像素灰度值服从同一独立的正态分布,基于此完成特征场模型的建立,再运用EM\MPM方法分别模拟特征场模型和分割影像。为了验证本文提出的算法能够有效地分割图像,分别对模拟图像和真实图像进行分割测试,并和经典的初始划分完全随机的超像素影像分割算法进行对比,测试结果定性和定量地表明了该方法的有效性和准确性。
文摘基于区域和统计的SAR分割方法,提出一种结合Voronoi划分技术、最大期望值EM(Expectation Maximization)和最大边缘概率MPM(Maximization of the Posterior Marginal)算法的多视SAR图像分割方法。首先利用Voronoi划分将图像域划分成不同的子区域,而每个子区域可以被看成待分割同质区域的一个组成部分,并假设每个子区域内的像素满足同一独立的Gamma分布,从而建立多视SAR图像模型,并在贝叶斯理论架构下建立图像分割模型,然后结合EM/MPM算法进行图像分割和模型参数估计。该方法将基于像元的马尔可夫随机场(Markov Random Field,MRF)模型扩展到基于区域的MRF模型,并且能同时有效地获取模型参数估计和基于区域的SAR图像最优分割。采用本文算法,分别对RADARSAT-Ⅰ/ⅡSAR强度图像和合成SAR强度图像进行了分割实验,定性和定量的测试结果验证了本文方法的有效性、可靠性和准确性。
基金The project supported by the Science Foundation of Laboratory of Computational Physics,Science Foundation of China Academy of Engineering Physics,and National Natural Science Foundation of China under Grant Nos.10702010,10775018,10472052,and 10604010
文摘A new multi-mesh contact algorithm for three-dimensional material point method is presented. The contact algorithm faithfully recovers the opposite acting forces between colliding bodies. Collision procedures between regular bodies and/or rigid bodies are treated within the same framework. Multi-value of momentum and mass are defined on every node to describe the contact/sliding/separation procedure. Both normal and tangential velocities of each particle at the contact surface are calculated in respective individual mesh. A Coulomb friction is applied to describe the sliding or slipping between the contacting bodies. The efficiency of the contact algorithm is linearly related to the number of the contacting bodies because the overlapped nodes are labeled by sweeping the material particles of all bodies when the nodal momentum and mass are formed at every time step. Numerical simulation shows that our contact algorithm possesses high accuracy and low numerical energy dissipation, which is very important for solving collision problems.
文摘The combination of Morgenstern-Price Method （MPM） with Response Surface Method （RSM） improves the eonventional RSM by replacing Finite-Element Method （FEM） with MPM, which is a type of reliability analysis method-RSM based on MPM, and makes the computing process simpler. The stability of the slope was re-evaluated by use of Monte Carlo method （MCM） and the result contrasted with the fore is the conclusion. The reliability analysis of the artificial slope in Donggang Power Station was carried on, and obtained the reliable charaeteristics, which provided basis for the project.
