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101.
利用张量理论研究一致超图的谱半径.首先,利用对角相似张量与原张量同谱的性质,结合张量特征值的圆盘定理,给出谱半径的上界,这一上界严格小于最大度;其次,通过超图的度向量给出谱半径的下界.改进了超图谱半径上下界的原有结果. 相似文献
102.
103.
《Journal of computational and graphical statistics》2013,22(3):464-486
In recent years, hierarchical model-based clustering has provided promising results in a variety of applications. However, its use with large datasets has been hindered by a time and memory complexity that are at least quadratic in the number of observations. To overcome this difficulty, this article proposes to start the hierarchical agglomeration from an efficient classification of the data in many classes rather than from the usual set of singleton clusters. This initial partition is derived from a subgraph of the minimum spanning tree associated with the data. To this end, we develop graphical tools that assess the presence of clusters in the data and uncover observations difficult to classify. We use this approach to analyze two large, real datasets: a multiband MRI image of the human brain and data on global precipitation climatology. We use the real datasets to discuss ways of integrating the spatial information in the clustering analysis. We focus on two-stage methods, in which a second stage of processing using established methods is applied to the output from the algorithm presented in this article, viewed as a first stage. 相似文献
104.
1IntroductionLetusa;onsi~~l'tile2-(1llTlellsiollalco'ttipetit;ion1,of-,ha--\./O]1,'lrra,s:\,s(t()lcfl.r]=.r,(l)j(t)--a,1(-t)xl--a,,(lt)x,),,.(II)ac=ac(6~(t-)--a21(t)x,--a22(t);rZ),xvhere(J:,.:x'2)eR;,~{(;t:l,.xZ)la:l20,IZ.20},l),(l),ail(t)fi{~j:lar(>conti… 相似文献
105.
N.M. Temme 《Numerical Algorithms》1997,15(2):207-225
Airy-type asymptotic representations of a class of special functions are considered from a numerical point of view. It is well known that the evaluation of the coefficients of the asymptotic series near the transition point is a difficult problem. We discuss two methods for computing the asymptotic series. One method is based on expanding the coefficients of the asymptotic series in Maclaurin series. In the second method we consider auxiliary functions that can be computed more efficiently than the coefficients in the first method, and we do not need the tabulation of many coefficients. The methods are quite general, but the paper concentrates on Bessel functions, in particular on the differential equation of the Bessel functions, which has a turning point character when order and argument of the Bessel functions are equal. 相似文献
106.
Consider the nonparametric regression model
, whereg is an unknown function to be estimated on [0, 1],
are the fixed design points in the interval [0, 1] and
is a triangular array of row iid random variables having median zero. The nearest neighbor median estimator
is taken as the estimator of the unknown functiong(x). Median cross validation (mev) criterion is employed to select the smoothing parameterh. Leth
π
*
be the smoothing parameter chosen by mev criterion. Under mild regularity conditions, the upper and lower bounds ofh
π
*
, the rate of convergence and the weak consistency of the median cross-validated estimate
are obtained.
Project supported by the National Natural Science Foundation of China and the Doctoral Foundation of Education of China. 相似文献
107.
108.
109.
110.
A scheduling problem with a common due-window, earliness and tardiness costs, and identical processing time jobs is studied. We focus on the setting of both (i) job-dependent earliness/tardiness job weights and (ii) parallel uniform machines. The objective is to find the job allocation to the machines and the job schedule, such that the total weighted earliness and tardiness cost is minimized. We study both cases of a non-restrictive (i.e. sufficiently late), and a restrictive due-window. For a given number of machines, the solutions of the problems studied here are obtained in polynomial time in the number of jobs. 相似文献