FOE estimation: Can image measurement errors be totally “corrected” by the geometric method?

For the FOE estimation, there are basically three kinds of estimation methods in the literature: algebraic, geometric, and the maximum likelihood-based ones. In this paper, our attention is focused on the geometric method. The computational complexity of the classical geometric method is usually very high because it needs to solve a non-linear minimum problem with many variables. In this work, such a minimum problem is converted into an equivalent one with only two variables and accordingly a simplified geometric method is proposed. Based on the equivalence of the classical geometric method and the proposed simplified geometric method, we show that the measurement errors can at most be “corrected” only in one of the two images by geometric methods. In other words, it is impossible to correct the measurement errors in both of the two images. In addition, we show that the “corrected” corresponding pairs by geometric methods cannot in general meet some of the inherent constraints of corresponding pairs under pure camera translations. Hence, it is not proper to consider the “corrected” corresponding pairs as “faithful” corresponding pairs in geometric methods, and the estimated FOE from such pairs is not necessarily trustworthier. Finally, a new geometric algorithm, which automatically enforces the inherent constraints, is proposed in this work, and better FOE estimation and more faithful corresponding pairs are obtained.     

关于AutoCAD参数化建模中标注约束运行机制的猜想

ObjectARX是一个能快速访问AutoCAD图形数据库的DLL,新版CAD自带的参数化功能也是利用ObjectARX对其进行二次开发实现的。这篇文章着重分析了CAD参数化功能中标注约束可能的运行机制。     

Robust Structure‐Based Shape Correspondence

We present a robust method to find region‐level correspondences between shapes, which are invariant to changes in geometry and applicable across multiple shape representations. We generate simplified shape graphs by jointly decomposing the shapes, and devise an adapted graph‐matching technique, from which we infer correspondences between shape regions. The simplified shape graphs are designed to primarily capture the overall structure of the shapes, without reflecting precise information about the geometry of each region, which enables us to find correspondences between shapes that might have significant geometric differences. Moreover, due to the special care we take to ensure the robustness of each part of our pipeline, our method can find correspondences between shapes with different representations, such as triangular meshes and point clouds. We demonstrate that the region‐wise matching that we obtain can be used to find correspondences between feature points, reveal the intrinsic self‐similarities of each shape and even construct point‐to‐point maps across shapes. Our method is both time and space efficient, leading to a pipeline that is significantly faster than comparable approaches. We demonstrate the performance of our approach through an extensive quantitative and qualitative evaluation on several benchmarks where we achieve comparable or superior performance to existing methods.     

外圆磨削参数优化模型及其应用

磨削加工工艺成本很高,磨削用量的选择意义重大。分析磨削用量及其对加工精度和生产率的影响,针对外圆磨削用量的选择,建立了以磨削多工序成本组成的工艺成本最低为目标的磨削参数优化模型。该模型以表面粗糙度、磨削工件刚度、磨床功率、磨床参数、磨削余量作为约束条件,以磨削余量、纵向进给量、横向进给量3个磨削参数为优化变量。以某型号电机轴为应用案例,运用MATLAB语言对其磨削参数进行了优化求解,与根据磨削手册和经验选择的磨削参数进行比较表明:优化后的外圆磨削工艺成本可降低近18%,从而验证了模型的有效性。     

反射几何布朗运动的两个结果

主要讨论反射几何布朗运动．首先通过采用马氏过程无穷小生成元的方法得到反射几何布朗运动的平稳分布,最后对该过程的首中时问题进行了讨论,得到该首中时的拉普拉斯变换．     

考虑剪切影响时结构的动力稳定分析

对大型结构考虑剪切影响及阻尼产生的几何刚度矩阵，在纵向载荷作用下的动力稳定问题进行了较详细的分析。给出了计算动力不稳定区域和激发载荷的方法。并把有限元和解析法结合在一起，利用二次摄动方法成功地获得纵向载荷作用的动力稳定问题的解。     

脉冲TIG焊接熔池几何参数的视觉检测

介绍了作者自行研制的脉冲 TIG(Tungsten Inert Gas)焊接熔池几何参数计算机视觉检测系统 .该系统从硬件上将特殊采样时序与复合滤光措施相结合 ,减小电弧光的干扰 ,从软件上针对熔池区图像的特点 ,利用快速有效的处理算法 ,能够从正面实时检测出熔池重要几何参数 ,如熔池的最大宽度、半长、后部面积、后拖角等 ,为下一步焊接过程实时控制打下了良好基础 .     

三维融入式工程图学教学研究

为培养学生的工程图学空间思维,强化其构型设计的能力并渗透现代三维工程设计理念,就如何利用多媒体方式将三维造型技术融入工程图学教学实践进行了探索.文章着重介绍了三维造型在组合体教学中的应用.     

冲击次数为Geometric过程的系统损伤模型及其可靠性指标

针对免赔保险中的理赔背景,将整个理赔过程看作一个系统损伤模型来刻画,建立了一类系统损伤的数学模型。该模型通过引入Geometric过程来刻画系统损伤次数,以指数分布来刻画系统冲击损伤值。并且针对这一分布下的系统损伤模型,研究了其寿命函数、可靠度、平均损伤、剩余寿命、平均剩余寿命、失效率等可靠性指标。     

一个可求解非线性约束的CLP编译方案及其优化

描述了一个优化的约束逻辑程序设计(CLP)系统的编译方法和编译优化策略.该系统是一个多重论域的CLP系统,以区间算术和约束传播作为离散域和实数域上约束求解的统一方法,具有求解非线性约束的功能.实现为一个基于扩充的WAM指令集的编译系统.在国内外已有的CLP系统中,我们尚未见到同时具有多重论域,非线性约束求解和编译实现这3项特征的类似系统.