Material state remapping in computational solid mechanics

A computational procedure for remapping material state information from one finite element mesh to another is described. The procedure is useful in connection with evolving meshes for inelastic problems, as for example occur in the context of fracture simulation and adaptive mesh refinement. The proposed method is based on weak enforcement of equality between corresponding fields on the two meshes, where piecewise‐constant fields on both meshes are generalized from the quadrature‐point values. The essential algorithmic problem is that of calculating the volume partition of an arbitrary convex region with respect to a covering set of disjoint convex regions. Instead of geometrically resolving the associated intersections, the problem is herein approximated by a constrained optimization problem, which may be readily and efficiently solved computationally. This formulation is a main contribution of the paper. Computational examples are given that illustrate the effectiveness of the proposed procedure. Copyright © 2002 John Wiley & Sons, Ltd.     

The visual control of reaching and grasping: Binocular disparity and motion parallax.

The primary visual sources of depth and size information are binocular cues and motion parallax. Here, the authors determine the efficacy of these cues to control prehension by presenting them in isolation from other visual cues. When only binocular cues were available, reaches showed normal scaling of the transport and grasp components with object distance and size. However, when only motion parallax was available, only the transpont component scaled reliably. No additional increase in scaling was found when both cues were available simultaneously. Therefore, although equivalent information is available from binocular and motion parallax information, the latter may be of relatively limited use for the control of the grasp. Binocular disparity appears selectively important for the control of the grasp. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

一种基于MPEG-2的立体视频编码中的视差匹配快速算法

高效，快速的视差匹配是立体视频处理中的一项关键技术。本文在分析立体图像序列的视差矢量与运动矢量之间的相关性的基础上，提出一种基于MPEG-2的立体视频编码中的视差匹配快速算法。实验结果表明，与全搜索法相比，在保证重建图像质量的前提下，快速算法能显著降低视差估计的计算复杂度。     

基于梯度值的自适应窗口立体图像匹配算法

针对基于区域的立体图像匹配算法支持窗口难以选择,容易出现窗口过大或过小的问题,提出一种新的自适应窗口立体图像匹配算法。该算法利用Sobel梯度算子计算像素梯度值,并根据其梯度值动态地获取具有自适应的支持窗口,然后分别选择相似性测度函数SAD或NCC搜索最佳匹配点,获得视差图。此外,算法在窗口选择过程中进行优化,减少了计算量。实验结果表明,改进后的算法提高了匹配正确率且计算时间缩短了近5%。     

Aging and availability of binocular disparity and pictorial depth cues in 3D graphics contents

Some stereoblind observers do not perceive depth of 3D stimuli that depends on binocular disparity. These individuals, who have no disabilities, comprise over 5% of the general population. In addition, 17–30% of nonstereoblind young and young–middle people do not use disparity information in certain 3D environments, a phenomenon known as pseudo‐stereoblindness. This study aimed to investigate the relationship between aging and the proportion of pseudo‐stereoblindness in the general population. In an experiment, 134 nonstereoblind participants, ranging in age from 17 to 83 years, judged subjective depth of 3D stimuli containing binocular disparity and pictorial depth cues. Results showed that the proportion of pseudo‐stereoblindness among young (17–24 years old) and young–middle aged observers (25–39 years old) was 29%, in both cases. However, the proportion of pseudo‐stereoblind observers increased in older populations: 65% and 82% in the middle (40–54 years old) and senior (55–83 years old) age groups, respectively. These results suggest that a number of people, especially in elderly populations, have trouble perceiving depth from binocular disparity in 3D graphic contents despite their essential ability to use disparity information.     

长江三角洲地区城乡收入差距测度

基于GE指数相关理论,测度了长江三角洲的城乡收入差距,测算和分析各种收入来源对城乡之间收入差距的影响度,得出了经营性收入对城乡收入差距的贡献率最大、工资性收入其次、财产性收入和转移性收入贡献率最小等结论。     

中国硬质合金产业的技术进步

简要介绍了中国硬质合金产业技术进步的历程,阐述了在超细硬质合金、涂层硬质合金、CAD/CAM技术、喷雾干燥和气压烧结方面取得的长足进步。指出了中国硬质合金产业与国外先进水平的四大差距,提出了组建国家硬质合金工程研究中心,加强宏观调控,快速提升应用技术水平和培育高水平人才等重要对策。     

自适应分层粒子群稠密视差图估计

分析了遗传算法的缺陷,提出了自适应分层粒子群(PSO)立体匹配算法计算稠密视差图。首先采用SIFT(scale invariant feature transform)特征检测和匹配算法准确地确定视差范围;其次根据图像和视差范围的大小分层,建立由粗及细的自适应分层图像金字塔结构,加快搜索速度、减少错误匹配;然后在优化函数中引入能根据匹配窗口大小自动变化的因子来调整灰度项和平滑项数据的权重,并用改进的带变异算子的整数形式的PSO进行优化,避免了遗传算法搜索的盲目性以及容易陷入局部最优的缺陷,更快、更好地找到最优解。最后合成图像以及真实图像的实验结果表明该方法精度较高,速度较快。     

区域与特征相结合的立体匹配算法

基于区域的匹配算法是立体匹配中常用的方法之一,而基于特征的匹配算法能解决区域匹配中遇到的某些问题,根据特征匹配与区域匹配的特点,提出了一种特征匹配与区域匹配相结合的立体匹配算法.首先在特征匹配中通过改进的Harris提取角点并结合单调性约束和惟一性约束进行匹配,特征匹配的结果能减少误匹配率,为区域匹配打下了基础.然后在...     

基于纹理分析的视差估计算法

针对传统方法难以可靠估计图像中纹理单一像素点视差的问题,提出一种新的基于纹理分析的视差估计算法。与已有方法不同,在以极线约束计算像素点视差时,将极线上纹理单一且近似的像素点合并成直线段,根据连续性和唯一性约束对直线段进行整体匹配,采用直线段的视差得到纹理单一区域的稠密视差图。利用直线段进行整体匹配,提高比较基元包含的信息量,减少扫描范围,从而降低误匹配产生的概率和算法时间复杂度。实验结果表明,该方法能提高纹理单一区域稠密视差图的精度,匹配速度快,具有实用价值。