二维Γ分布参数与水文统计参数之间关系的研究

本文导出了W.F.kibble的二维Г分布密度函数中各参数与水文统计参数的关系,并作出了讨论。最后给出了应用实例。     

Multidimensional scaling in the city-block metric: A combinatorial approach

We present an approach, independent of the common gradient-based necessary conditions for obtaining a (locally) optimal solution, to multidimensional scaling using the city-block distance function, and implementable in either a metric or nonmetric context. The difficulties encountered in relying on a gradient-based strategy are first reviewed: the general weakness in indicating a good solution that is implied by the satisfaction of the necessary condition of a zero gradient, and the possibility of actual nonconvergence of the associated optimization strategy. To avoid the dependence on gradients for guiding the optimization technique, an alternative iterative procedure is proposed that incorporates (a) combinatorial optimization to construct good object orders along the chosen number of dimensions and (b) nonnegative least-squares to re-estimate the coordinates for the objects based on the object orders. The re-estimated coordinates are used to improve upon the given object orders, which may in turn lead to better coordinates, and so on until convergence of the entire process occurs to a (locally) optimal solution. The approach is illustrated through several data sets on the perception of similarity of rectangles and compared to the results obtained with a gradient-based method.     

基于Gauss滤波的图像可视化检索(Ⅱ)——全局匹配

基于多尺度Gauss滤波的图像特征提取 ,能够在较大的尺度和视角变化范围内 ,检索出具有相似外观特征的图像。在讨论多尺度Gauss滤波输出用于图像的局部相似性匹配检索的基础上 ,进一步分析了如何将多尺度Gauss滤波方法用于全局相似性匹配检索。首先由图像在不同尺度下的Gauss滤波输出 ,构造出图像的曲率和相位直方图 ,得到图像的多尺度直方图表示 ;然后查询图像和数据库图像的归一化的曲率和相位直方图再进行匹配。归一化的直方图因消除了图像中点的位置信息 ,因此是图像变换如 :旋转、扭曲、拉伸下的不变量。该方法能用到基于图像外观特征的全局可视化检索中 ,并能取得很好的效果     

部分预应力混凝土受弯构件延性计算

在介绍和分析国外有关部分预应力混凝土受弯构件延性计算方法的基础上,提出了一个简化计算方法,并将计算结果与作者所完成试验的结果相比较。经比较可见,本文所提出的计算方法考虑因素较全面,计算值与试验结果符合程度更好。     

《牛顿环》实验方法的探讨

对“牛顿环”实验进行了全面分析,提出了现行教材中存在的问题和另一种可行的测量方法。     

双进组合三角恒等式的多重推广

给出了系数为双进组合三角的恒等式的多重推广,进而推广了I．J．Matrix定理。     

Lower Bounds and a Nearly Fastest General Parallel Branch-and-Bound Algorithm

In this paper, it is supposed that the B&B algorithm finds the first optimal solution after h nodes have been expanded and m active nodes have been created in the state-space tree. Then the lower bound Ω(m＋hlog h) of the running time for the general sequential B&B algorithm and the lower bound Ω(m/p ＋ hlogp) for the general parallel best-first B&B algorithm in PRAM CREW are proposed, where p is the number of processors available. Moreover, the lower bound Ω(M/p＋H＋ (H/p) log (H/p)) is presented for the parallel algorithms on distributed memory system, where M and H represent total number of the active nodes and that of the expanded nodes processed by p processors, respectively. In addition, a nearly fastest general parallel best-first B&B algorithm is put forward. The parallel algorithm is the fastest one az p ＝ max{he,r}, where ε ＝ 1/logh, and r is the largest branch number of the nodes in the state-space tree.     

用有限组合元法分析外包T型叶根小脚装配间隙的影响

本文通过有限组合元法分析了外包小脚装配间隙对叶根轮缘强度的影响。得出了在工艺许可条件下,小脚装配间隙宜尽量减小的结论。     

神经网络的非线性动力学性质与组合优化

本文综述了神经网络理论发展的历史和现状,详细介绍了神经网络的非线性动力学性质与组合优化问题,提出了该问题的研究内容和展望.     

重力场中液滴特征的研究

本文认为在重力场中运动速度不很快的液滴具有与静止液滴相同的形状,研究表明这种液滴同样满足皂泡方程,且其上部和下部的体积相等.通过对表面方程的讨论,找到了表面曲率半径与滴重、表面张力等之间的关系.