基于实数结构元素的多角度边缘检测算法

由于传统的边缘提取方法如Sobel、Robert、Prewitt、Log和Canny等对噪声十分敏感,而基于传统数学形态学的边缘检测算法又不能很好地利用空间信息,很难对复杂边界进行有效的处理.本文提出基于实数结构元素的多角度边缘检测算法,该算法可以充分地反映空间距离以及各个角度对边缘检测的影响.最后通过实验说明该算法在复杂图像的边缘提取中不仅有很强的抗噪性,而且可以有效地提取图像边缘.     

基于ANSYS二次开发的夹层玻璃面板有限元分析

为了准确地计算夹层玻璃面板的受力特性,基于ANSYS二次开发,考虑大位移非线性效应,实现了夹层玻璃面板仿真分析。在有限元分析中充分考虑了PVB(Polyvinyl Butyral)胶片对夹层玻璃面板承载力的影响。同时利用VB平台开发了界面友好,操作便捷,完全参数化的分析程序。通过实例论述了利用VB对ANSYS进行二次开发的关键技术,有效地提高了ANSYS在工程分析中的效率,为幕墙设计人员提供了有益的参考。     

Application of the Galerkin and Least-Squares Finite Element Methods in the solution of 3D Poisson and Helmholtz equations

This paper presents the numerical solution, by the Galerkin and Least Squares Finite Element Methods, of the three-dimensional Poisson and Helmholtz equations, representing heat diffusion in solids. For the two applications proposed, the analytical solutions found in the literature review were used to compare with the numerical solutions. The analysis of results was made from the L₂ norm (average error throughout the domain) and L_∞ norm (maximum error in the entire domain). The results of the two applications (Poisson and Helmholtz equations) are presented and discussed for testing of the efficiency of the methods.     

钢材料电磁应力传感器技术研究

现代结构普遍大量使用铁磁性钢材料作为承载构件,其受力状态直接关系到结构整体的安全性。由于应力对钢材料磁特征参量的影响比较显著,故在分析了基本原理的前提下,设计了一种管筒式电磁应力传感器。采用有限元仿真技术FLUX软件检验磁路设计的合理性,并提出了实验与仿真相结合的方法对传感器输出电压进行标定。通过实验与仿真计算结果对比,验证了该种方法的正确性,为该种应力检测传感器提供了一种高效的标定方法,使其更加具有市场价值。     

微机械气流式倾角传感器的研究

提出了一种能敏感倾角的微机械气流式传感器.采用微机械工艺在硅板上腐蚀出一个深槽,在深槽上设置2个有金属薄膜热敏电阻器的悬臂梁,用半圆球外壳封装成一个密闭腔体形成敏感元件;通过惠斯登电桥提取倾角电压信号;利用单片机和温度传感器构成补偿电路,实现温度补偿和线性度补偿.测试结果表明:测量范围为+30°,分辨率为优于0.1°,...     

圆锥壳开孔与围栏加强力学特性分析

圆锥壳由于锥角的存在,其开孔的力学特性比圆柱壳开孔更为复杂.通过有限元方法分析圆锥壳半锥角对开孔应力集中系数的影响,认为开孔偏斜角越大,导致的应力集中系数越大;并在此基础上,研究了圆锥壳开孔大小α/R对应力集中系数的影响规律.并分析了加强围栏的长度变化对孔应力集中系数的影响,表明围栏是圆锥壳开孔加强的有效措施.     

A subject-specific software solution for the modeling and the visualization of muscles deformations

Today, to create and to simulate a virtual anatomical version of a subject is useful in the decision process of surgical treatments. The muscular activity is one of the factors which can contribute to abnormal movements such as in spasticity or static contracture. In this paper, we propose a numerical solution, based on the Finite Element (FE) method, able to estimate muscles deformations during contraction. Organized around a finite element solver and a volumetric environment, this solution is made of all the modeling and simulation processes from the discretization of the studied domain to the visualization of the results. The choices of materials and properties of the FE model are also presented such as the hyperelasticity, the contention model based on inter-meshes neighboring nodes pairing, and the estimation of nodal forces based on the subject-specific muscular forces and action lines.

The geometric element transformation method for mixed mesh smoothing

The geometric element transformation method (GETMe) is a geometry-based smoothing method for mixed and non-mixed meshes. It is based on a simple geometric transformation applicable to elements bounded by polygons with an arbitrary number of nodes. The transformation, if applied iteratively, leads to a regularization of the polygons. Global mesh smoothing is accomplished by averaging the new node positions obtained by local element transformations. Thereby, the choice of transformation parameters as well as averaging weights can be based on the element quality which leads to high quality results. In this paper, a concept of an enhanced transformation approach is presented and a proof for the regularizing effect of the transformation based on eigenpolygons is given. Numerical examples confirm that the GETMe approach leads to superior mesh quality if compared to other geometry-based methods. In terms of quality it can even compete with optimization-based techniques, despite being conceptually significantly simpler.     

A split least-squares characteristic mixed finite element method for Sobolev equations with convection term

In this paper, a split least-squares characteristic mixed finite element method for a kind of Sobolev equation with convection term is proposed, in which the characteristic method is based on the approximation of the material derivative term, that is, the time derivative term plus the convection term. The resulting least-squares procedure can be split into two independent symmetric positive definite sub-schemes and does not need to solve a coupled system of equations. Theory analysis shows that the method yields the approximate solutions with optimal accuracy in L²(Ω) norm for the primal unknown and in H(div;Ω) norm for the unknown flux, respectively. Numerical examples in one dimension, which are consistent with the theoretical results, are provided to demonstrate the characteristic behavior of this approach.     

Algorithm,software, and hardware optimizations for Delaunay mesh generation on simultaneous multithreaded architectures

This article focuses on the optimization of PCDM, a parallel, two-dimensional (2D) Delaunay mesh generation application, and its interaction with parallel architectures based on simultaneous multithreading (SMT) processors. We first present the step-by-step effect of a series of optimizations on performance. These optimizations improve the performance of PCDM by up to a factor of six. They target issues that very often limit the performance of scientific computing codes. We then evaluate the interaction of PCDM with a real SMT-based SMP system, using both high-level metrics, such as execution time, and low-level information from hardware performance counters.