一种计算机建立多刚体动力学方程的方法

本文以多刚体动力学Kane方程的基本形式为出发点,通过对该方程的重新描述,编制了通用的自动建立动力学方程程序。对于一般多刚体系统,只要输入基本力学量就能由计算机完成动力学方程的推导,并输出易于数值解法的Fortran语言格式程序,避免了大量的手工推导工作,尤其对大自由度系统更能显示其方便性。     

Learning-based tracking of complex non-rigid motion

This paper describes a novel method for tracking complex non-rigid motions by learning the intrinsic object structure. The approach builds on and extends the studies on non-linear dimensionality reduction for object representation, object dynamics modeling and particle filter style tracking. First, the dimensionality reduction and density estimation algorithm is derived for unsupervised learning of object intrinsic representation, and the obtained non-rigid part of object state reduces even to 2-3 dimensions. Secondly the dynamical model is derived and trained based on this intrinsic representation. Thirdly the learned intrinsic object structure is integrated into a particle filter style tracker. It is shown that this intrinsic object representation has some interesting properties and based on which the newly derived dynamical model makes particle filter style tracker more robust and reliable.Extensive experiments are done on the tracking of challenging non-rigid motions such as fish twisting with selfocclusion, large inter-frame lip motion and facial expressions with global head rotation. Quantitative results are given to make comparisons between the newly proposed tracker and the existing tracker. The proposed method also has the potential to solve other type of tracking problems.     

刚体位移测量的数字散斑相关法的研究

结合计算机辅助测试CAT和虚拟仪器技术,阐述了数字散斑相关方法DSCM(Digital Speckle Correlation Method)测量刚体位移的理论与过程。同时针对求解三参数相关系数最大值点提出了一种“编程简单、时间节省、精度良好”的实用新算法,即“正方体爬山搜索法”。并利用仿真实验进行了成功验证,仿真实验效果非常理想,测量值与给定理论值相比很接近,计算速度也比较快。     

非均匀地基上自由梁的刚体模态分析

非均匀单参数(Winkler)地基和双参数(Pasternak)地基上自由梁的刚体模态与梁体—土体间的相互作用有关,当约束或支承不影响梁的平动和转动时,相应的刚体模态则会出现.刚体模态的频率和振型随的地基的不均匀性和基床系数的变化而变化.基于哈密顿原理和变化运算,获得了考虑周围土体支承影响的双参数地基梁振动特性,并分析了不均匀地基上自由梁的广义刚体模态频率及其随地基不均性的变化规律.     

基于非刚体运动光流算法的面部表情识别

本文讨论了基于光流法的面部表情识别。由于面部表情运动是一非刚体运动，容易产生形变，因此标准光流法估计不准确。为此，本文通过引入div-curl样条函数作为扩展光流约束方程的附加约束条件，推导了非刚体光流算法，并给出了一阶和二阶div-curl样条约束下光流的数值解。最后将该算法用于面部表情特征提取，构建了HMM与BP神经网络混合分类器。实验结果表明面部表情识别率得到显著提高。     

基于一维标定物的多摄像机标定

一维标定物是由三个或三个以上彼此距离已知的共线点构成的. 现有文献指出只有当一维标定物做平面运动或者绕固定点转动时，才能实现摄像机的标定. 本文的研究结果表明，当多个摄像机同时观察作任意刚体运动的一维标定物时，则该摄像机组能被线性地标定. 本文给出一种线性标定算法，并使用最大似然准则对线性算法结果进行精化. 模拟实验和真实图像实验都表明本文的算法是有效可行的.     

Unstructured finite volume method for water impact on a rigid body

A new method is presented for the water impact simulation, in which the air-water two phase flow is solved using the pressure-based computational fluid dynamics method. Theoretically, the air effects can be taken into account in the water structure interaction. The key point of this method is the air-water interface capture, which is treated as a physical discontinuity and can be captured by a well-designed high order scheme. According to a normalized variable diagram, a high order discrete scheme on unstructured grids is realised, so a numerical method for the free surface flow on a fixed grid can be established. This method is implemented using an in-house code, the General Transport Equation Analyzer, which is an unstructured grid finite volume solver. The method is verified with the wedge water and structure interaction problem.     

巴基斯坦高摩赞大坝枢纽工程拱坝坝肩稳定分析

在拱坝的设计过程中,常进行坝肩稳定性分析。采用了有限元法对拱坝受力进行分析,然后利用有限单元分析的结果采用刚体极限平衡法进行计算。结合巴基斯坦高摩赞工程右坝肩F2和F3断层形成的滑动体进行典型分析。     

小南海水电站左岸溢流坝抗滑稳定分析

小南海水电站左岸溢流坝坝基内发育有层间剪切带、地层挠曲、顺河向的长大裂隙等,使其存在抗滑稳定问题。经分析该坝段的工程地质条件,确定坝基中可能出现的深层滑动破坏模式后,分别运用刚体极限平衡法和基于FLAC 3D的强度折减法计算坝基抗滑稳定安全系数,对比分析两种方法的计算成果。由强度折减法计算所得的安全系数均高于混凝土重力坝设计规范中规定的安全系数1.10,表明坝基的可能破坏模式不会发生,而刚体极限平衡法所得安全系数较强度折减法偏小,表明坝基的双斜滑动失稳模式可能发生,需要引起注意。但是对于不同的下游反向缓倾角裂隙倾角,两种方法所得安全系数的关系曲线变化趋势是一样的,倾角为40°时安全系数最小。