Finding Adam in random growing trees

We investigate algorithms to find the first vertex in large trees generated by either the uniform attachment or preferential attachment model. We require the algorithm to output a set of K vertices, such that, with probability at least , the first vertex is in this set. We show that for any ε, there exist such algorithms with K independent of the size of the input tree. Moreover, we provide almost tight bounds for the best value of K as a function of ε. In the uniform attachment case we show that the optimal K is subpolynomial in , and that it has to be at least superpolylogarithmic. On the other hand, the preferential attachment case is exponentially harder, as we prove that the best K is polynomial in . We conclude the paper with several open problems. © 2016 Wiley Periodicals, Inc. Random Struct. Alg., 50, 158–172, 2017     

张弦梁(桁架)结构的找形方法——分级卸载法

对张弦梁(桁架)结构的找形问题进行了深入研究,根据该类结构的受力特点,提出了分级卸载法。该方法无需假定结构零状态几何,而可以一次得到对应于初状态(即预应力态)几何的结构施工放样尺寸(即零状态几何),并通过分级加载对该方法的精度进行了检验。     

A procedure for the static analysis of cable structures following elastic catenary theory

The paper proposes an unitary strategy for the static analysis of general cable nets under conservative loads. A form-finding is first performed in order to initialize the successive non linear analysis. The numerical procedures carried on in both steps, form finding and structural analysis of the net, employ a three dimensional elastic catenary element. Equilibrium conditions at internal nodes and kinematic compatibility at the end nodes of each cable are used to derive the global equations of the net. When the pre-stresses are high and the topology of the net is involved, an accurate initializing solution is essential for the convergence of the successive numeric non linear structural analysis (performed by Newton method). The numerical applications highlight the capability of the proposed procedure to solve three dimensional problems with taut and slack cables, out of plane distributed forces (modeling wind loads), point loads along the cables. The contemporary presence of cables and compression truss elements is also considered testing the effectiveness of the method in the analysis of tensegrity structures.     

房地产业上市公司的统计数据挖掘分析研究

应用统计类数据挖掘技术对房地产业上市公司财务进行了分析。即搜集十五个房地产业上市公司的主要财务指标进行因子分析,用提取主成份的方法缩减变数,归纳出影响公司财务状况的四个主要因素。然后,对十五家房地产上市公司进行聚类分析,划分各公司的经营等级。最后,结合因子分析与聚类分析的结果对各公司的经营状况进行了综合评价,并以此指导投资者和经营管理者做出正确的决策。     

Vision system for three-dimensional position measurement based on stereo disparity

A stereo disparity-based range finding technique was developed for measuring three-dimensional coordinates of object points. It used an image-matching algorithm which functionally consisted of scene reduction, epipolar line selection, and features matching. Experiments implementing this technique were performed on an industrial vision system. An error analysis indicated that image resolution was the major source of measurement inaccuracy.     

C0复杂度的数学基础

对于许多同时具有强烈非线性和非平稳性的连续生物医学信号来说，计算其复杂度往往要求：1）在数据长度比较短的情况下也可以得出比较鲁棒的估计值；2）无需对原始信号作像二值化这样的过分的粗粒化，我们以前所提出的C0复杂度就是这样的一种度量，但是这种度量缺乏严格的数学基础，因而影响到它的应用，提出了一种改进形式，并严格证明了它的重要性质。从而表明这个量在一定条件下可以作为时间序列随机程度的指标，因而在随机性复杂度的意义下也可作为复杂性的一个定量指标，由于这个量有计算速度快的优点，因此特别适合于一些需要大量计算复杂度的场合，例如计算长时间过程中滑动窗口中复杂度的动态变化。     

Some computational methods for systems of nonlinear equations and systems of polynomial equations

This paper gives a brief survey and assessment of computational methods for finding solutions to systems of nonlinear equations and systems of polynomial equations. Starting from methods which converge locally and which find one solution, we progress to methods which are globally convergent and find an a priori determinable number of solutions. We will concentrate on simplicial algorithms and homotopy methods. Enhancements of published methods are included and further developments are discussed.     

3-D imaging and modeling – Part I: acquisition and registration

The key modules in a typical reverse engineering system consist of the acquisition, registration, and the integration of range images of three-dimensional objects with complex geometry. We first present a self-made optical digitizer that is employed for quickly acquiring range data from multiple views, then introduce a visualized registration procedure that can provide a reliable estimate for the fine registration of multiple range images in a unified coordinate system. Experiment results are given to show the effectiveness of this approach in 3-D imaging and multiple range image registration for the applications of reverse engineering.     

CCD激光测距实验

CCD激光测距实验是集光、机、电为一体的综合性实验，学生可以用简单的几何光学知识、采用激光遥感方式实现距离的非接触精确测量．本文简述了实验原理，给出了计算机自动处理和显示的系统硬件和软件环境，以及系统的校准方法，最后介绍了模拟实验结果。