共查询到20条相似文献，搜索用时 203 毫秒
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设G是一个 2连通简单图 ,具有阶n和连通度k .Bauer等人已证明 :如果对任意三点独立集S =u ,v ,w ,都有d(u) +d(v) +d(w)≥n +k ,则G是Hamilton图 .本文改进了这个结果 .如果一个独立集S中存在距离为 2的 2点 ,则称S是一个 2独立集 .本文证明了如下结果 :如果对任意 3点 2独立集S =u ,v ,w ,都有d(u) +d(v) +d(w)≥n +k .则G是Hamilton图 .这个结果意味我们仅需要检查所有 2独立集是否满足条件 相似文献
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在曲面匹配过程中,需要大量计算测量点到设计曲面的最近点及其距离,这一过程需要大量时间。而求解测量点到设计曲面距离的快速算法是解决曲面匹配问题的关键所在。如果采用测量数据点沿曲面法向投影到设计曲面,通过求解与曲面的交点得到最近点解,由于需要计算曲面上各位置处的法向,这样计算量较大。为简化算法,本文提出了一种近似的设计曲面上测量数据点最近点的计算方法。 相似文献
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本文重点研究了形如1|p j=f j(u j),u∑j=1uj≤,chains|∑wjcj型在链不可中断的情况下连续型问题的算法及其算法复杂性,分别讨论了p j=f j(u j)是线性函数、非线性函数的情况,给出了最优排序和最优资源分配及其稳定点的定义,同时证明了由此所求出的资源分配u*确系最优资源分配. 相似文献
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一个时间点上的多指标评价对象的排序问题已有不少研究,而对多个时间点上的多指标系统进行动态综合评价研究较少。利用主分量分析和理想点法,给出了时序多指标对象排序的一种方法,并通过实例说明了此方法的合理性。 相似文献
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提出一种在数字音频信号中嵌入水印的算法，该算法基于离散傅里叶变换域，嵌入的水印不是传统的伪随机序列形式，而是视觉可辨的二值图像。首先将二维图像降成一维序列．然后对数字音频信号作分段离散傅里叶变换，最后在离散傅里叶变换域内．通过量化分段的音频信号的频域系数嵌入水印。在水印的嵌入过程中使用了伪随机排序技术。 相似文献
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在C语言中,排序是数据处理中经常要遇到的一种重要运算,其功能是按某种指定顺序将一个数据元数的无序序列调整为一个有序序列.分析、讨论和比较了排序的三种通用算法,即交换排序法、选择排序法和插入排序法,同时也提供了一种改进的排序算法———快速排序法. 相似文献
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张先叶 《渭南师范学院学报》2014,(15):11-12
对梅向明、黄敬之编写的《微分几何》教材中的3个知识点提出不同意见：曲面网的方程是一个一阶非线性微分方程;直纹面方程 r→＝a→（u ）＋vb→（u）中,参数｜v｜为导线上a→（u）点到直母线上任一点P（u,v）的距离,b→（u）也可以只是过导线上a→（u）点的直母线上的方向向量;可展曲面上动点P沿一条直母线移动时,它的法向量始终共线,切平面不变。 相似文献
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提出了一种自适应B-样条曲面重构的算法，并利用Matlab语言实现了基于散乱数据的B-样条曲面重构的可视化． 相似文献
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提出了平面散乱数据点集曲线重构的最短路逼近算法,它创造性地把散乱数据点集的曲线重构问题转化为图论中带权连通图的最短路求解问题。新方法根据散乱数据点的分布情况构造平面上的势函数,并对散乱数据点集进行Delaunay三角化。根据势函数对Delaunay三角网格的每条边赋一个权值,生成带权连通图。在带权连通图上生成重构曲线两端点间的逼近路径,简化逼近路径,找出该路径上的关键点。以关键点为控制点,势函数值为权值,生成有理B样条曲线。最短路逼近算法在实验中取得很好的效果,成功解决了移动最小二乘法难以解决的具有尖点特征的数据点集的曲线重构问题。 相似文献
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王瑞 《唐山师范学院学报》2013,(4):17-20
伊瑟尔指出,文学文本给读者提供了一个“图示化”的框架,这个框架在各个层面上都有许多“空白”,需要读者在阅读过程中去填补与充实。小说艺术的创作也要借助“空白”的设置,刻画典型人物,巧妙安排故事情节以及文本结构,借助虚构和想象来塑造艺术形象,反映现实生活。小说艺术中的空白主要表现在语言符号层、艺术形象层以及内在意蕴层三个层面上。 相似文献
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LIU Guang-hui CHEN Chuan-bo 《浙江大学学报(A卷英文版)》2007,8(8):1210-1217
When the edges of a convex polygon are traversed along one direction,the interior of the convex polygon is always on the same side of the edges. Based on this characteristic of convex polygons,a new algorithm for computing the convex hull of a simple polygon is proposed in this paper,which is then extended to a new algorithm for computing the convex hull of a planar point set. First,the extreme points of the planar point set are found,and the subsets of point candidate for vertex of the convex hull between extreme points are obtained. Then,the ordered convex hull point sequences between extreme points are constructed separately and concatenated by removing redundant extreme points to get the convex hull. The time complexity of the new planar convex hull algorithm is O(nlogh) ,which is equal to the time complexity of the best output-sensitive planar convex hull algorithms. Compared with the algorithm having the same complexity,the new algorithm is much faster. 相似文献
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提出一种减少采样点计算的改进光线投射算法进行医学体数据面绘制，以达到缩短体绘制时间的效果。同时给出改进算法的具体实现及关键步骤。最后给出本次改进算法的实验结果。 相似文献
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主流形和非线性维数化简的切向空间校正 总被引：8，自引：0，他引：8
We present a new algorithm for manifold learning and nonlinear dimensionality reduction. Based on a set of unorganized da-ta points sampled with noise from a parameterized manifold, the local geometry of the manifold is learned by constructing an approxi-mation for the tangent space at each point, and those tangent spaces are then aligned to give the global coordinates of the data pointswith respect to the underlying manifold. We also present an error analysis of our algorithm showing that reconstruction errors can bequite small in some cases. We illustrate our algorithm using curves and surfaces both in 2D/3D Euclidean spaces and higher dimension-al Euclidean spaces. We also address several theoretical and algorithmic issues for further research and improvements. 相似文献
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INTRODUCTIONTheOSSI(OffsetSurface/SurfaceIntersection)problemisasub-problemofgeneralSSI.AlthoughtheOSSIproblemcanberesolvedbyapplyinggeneralSSIalgorithm,itiscomputationallyexpensiveandexhaustive.Inrecentdecades,effortshavebeenfocusedoncomputingSSIexactly,efficiently,androbustlyinageneralsetting(Abdel-MalekandYeh,1997;Changetal.,1994;BurkeandSabharwal,1996;Mullenheim,1991).Thesetechniquescanbeclassifiedmainlyintofivecategories:algebraic,latticeevaluation,marching(tracing)method,… 相似文献
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基于一种新的曲率分析算法对散乱数据点云分块 总被引：4，自引：0，他引：4
给出了数据分块系统性方案, 即从仅含有三维坐标的散乱的点云中自动提取几何曲面特性. 首先基于局部基面参数化估算散乱数据点云的局部表面曲率分析是其方案的关键性技术. 再采用由高斯曲率和平均曲率的记号得到的8种曲面类型, 就形成初始数据分块. 通过区域增长法可以使粗略数据分块进一步被提取, 得到更小的噪声影响及更精确的区域划分. 其方案得到了实例验证, 具有较强的可操作性和实用性. 基于新曲率算法的分块方案使数据分块技术能够直接运用于散乱数据点云. 相似文献
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Conventional methods for solving intersections between two offset parametric surfaces often include iteratively using computationally
expensive SSI (surface/surface intersections) algorithm. In addition, these methods ignore the relations between the intersection
curves of parametric surfaces with different offset distances. The algorithm presented in this paper, makes full use of the
topological relations between different intersection loops and calculates intersection loops with the help of previously calculated
intersection loops. It first pre-processes two parametric surfaces to obtain the characteristic points, called topology transition
points (TTPs), which can help in the subsequent finding of the topologies of the intersection curves. Then these points are
categorized into several distinct groups, and we can determine the calculation strategy for searching initial points by analyzing
the properties of these TTPs on the surfaces. Hence, all intersection curves can be marched from initial points by the tracing
algorithm. The proposed algorithm could calculate intersection curves robustly and effectively, and has been tested to be
capable of overcoming the degenerate conditions such as loop and singularities leaking that occur frequently in conventional
algorithms.
Project supported by the National Research Foundation for the Doctoral Program (No. 2000033554) of Higher Education of China
and the Natural Science Foundation of Zhejiang Province, China (No. 6001107) 相似文献
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A non-local denoising （NLD） algorithm for point-sampled surfaces （PSSs） is presented based on similarities, including geometry intensity and features of sample points. By using the trilateral filtering operator, the differential signal of each sample point is determined and called ＂geometry intensity＂. Based on covariance analysis, a regular grid of geometry intensity of a sample point is constructed, and the geometry-intensity similarity of two points is measured according to their grids. Based on mean shift clustering, the PSSs are clustered in terms of the local geometry-features similarity. The smoothed geometry intensity, i.e., offset distance, of the sample point is estimated according to the two similarities. Using the resulting intensity, the noise component from PSSs is finally removed by adjusting the position of each sample point along its own normal direction. Experimental results demonstrate that the algorithm is robust and can produce a more accurate denoising result while having better feature preservation. 相似文献