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排序方式: 共有41条查询结果,搜索用时 46 毫秒
1.
The paper analyses the convergence of sequences of control polygons produced by a binary subdivision scheme of the form
相似文献
2.
E. P. Svidritskii M. Sh. Jiang V. I. Il’in D. I. Dyn’kov A. V. Pirogov O. A. Shpigun 《Moscow University Chemistry Bulletin》2010,65(1):42-48
A procedure for simultaneous determination of alendronate, chloride, phosphite, phosphate, and methylsulphonate anions is
proposed. These ions are the main admixtures in synthetic alendronic acid, and their content should be controlled when producing
pharmaceutical preparations of alendronic acid. The developed method makes it possible to determine all the indicated ions
over a period of 4 min. Excellent efficiency (200000–500000 theoretical plates) makes it possible to determine ions even with
a high content of one of the components. The detection limits are 0.4−2.3 mg/l. The developed method has been successfully
applied for the analysis of methanesulfonic acid regenerated from the reaction mixture. 相似文献
3.
The uniqueness of monosplines and perfect splines of leastL p-norm is treated in the framework of generalized monosplines and total positivity. The analysis is based on the invariance properties of the degree of a certain mapping and on a new composition result for totally positive kernels. For theL p-case 1<p<∞, uniqueness is shown under the same extra conditions as were previously shown to be needed in theL p-case. The uniqueness in theL ∞-case is obtained without any restrictions. 相似文献
4.
Meshfree Thinning of 3D Point Clouds 总被引:1,自引:0,他引:1
An efficient data reduction scheme for the simplification of a surface given by a large set X of 3D point-samples is proposed. The data reduction relies on a recursive point removal algorithm, termed thinning, which
outputs a data hierarchy of point-samples for multiresolution surface approximation. The thinning algorithm works with a point
removal criterion, which measures the significances of the points in their local neighbourhoods, and which removes a least
significant point at each step. For any point x in the current point set Y⊂X, its significance reflects the approximation quality of a local surface reconstructed from neighbouring points in Y. The local surface reconstruction is done over an estimated tangent plane at x by using radial basis functions. The approximation quality of the surface reconstruction around x is measured by using its maximal deviation from the given point-samples X in a local neighbourhood of x. The resulting thinning algorithm is meshfree, i.e., its performance is solely based upon the geometry of the input 3D surface
point-samples, and so it does not require any further topological information, such as point connectivities. Computational
details of the thinning algorithm and the required data structures for efficient implementation are explained and its complexity
is discussed. Two examples are presented for illustration.
This paper is dedicated to Arieh Iserles on the occasion of his 60th anniversary. 相似文献
5.
Summary We develop multivariate interpolation methods constructed from sums of radial functions.Dedicated to Professor G. Hämmerlin with esteem on the occasion of his sixtieth birthdayThis work was supported by the USA-Israel Binational, Science Foundation Grant no. 86-00243 相似文献
6.
Approximation properties of the dilations of the integer translates of a smooth function, with some derivatives vanishing
at infinity, are studied. The results apply to fundamental solutions of homogeneous elliptic operators and to “shifted” fundamental
solutions of the iterated Laplacian. Following the approach from spline theory, the question of polynomial reproduction by
quasi-interpolation is addressed first. The analysis makes an essential use of the structure of the generalized Fourier transform
of the basis function. In contrast with spline theory, polynomial reproduction is not sufficient for the derivation of exact
order of convergence by dilated quasi-interpolants. These convergence orders are established by a careful and quite involved
examination of the decay rates of the basis function. Furthermore, it is shown that the same approximation orders are obtained
with quasi-interpolants defined on a bounded domain.
Supported in part by the United States under contract No. DAAL-87-K-0030, and by Carl de Boor’s Steenbock Professorship, University
of Wisconsin-Madison. 相似文献
7.
The purpose of this paper is to study certain variational principles and Sobolev-type estimates for the approximation order
resulting from using strictly positive definite kernels to do generalized Hermite interpolation on a closed (i.e., no boundary),
compact, connected, orientable, m -dimensional C
∞
Riemannian manifold , with C
∞
metric g
ij
. The rate of approximation can be more fully analyzed with rates of approximation given in terms of Sobolev norms. Estimates
on the rate of convergence for generalized Hermite and other distributional interpolants can be obtained in certain circumstances
and, finally, the constants appearing in the approximation order inequalities are explicit. Our focus in this paper will be
on approximation rates in the cases of the circle, other tori, and the 2 -sphere.
April 10, 1996. Dates revised: March 26, 1997; August 26, 1997. Date accepted: September 12, 1997. Communicated by Ronald
A. DeVore. 相似文献
8.
9.
Four-term recurrence relations with constant coefficients are derived for a wide class of T chebycheffian B-splines, LB-splines
and complex B-splines. Such a relation exists whenever the differential operator defining the underlying “polynomial” space
can be factored in two essentially different ways. The four lower order B-splines in the recurrence relation appear in two
pairs, each pair corresponding to one of these factorization. It is shown that the two-term recurrence relations for polynomial,
trigonometric and hyperbolic B-splines as well as other known two-term recurrence relations are obtained directly from the
four-term recurrence relations in a unified and systematic way. The above derivation also yields two different two-term recurrence
relations for Green’s functions of these “polynomial” spaces In this context the special examples of exponential functions
and rational functions are analyzed in detail. 相似文献
10.
Summary We say that a curve has geometric continuity if its curvatures and Frenet frame are continuous. In this paper we introduce spaces of piecewise polynomials which can be used to model space curves which have geometric continuity. We show that the basic theoretical properties of ordinary spline functions also hold for these spaces. These results extend and unify recent work on Beta-splines and Nu-splines which are used as a design tool in computer-aided geometric design of free form curves and surfaces.This work was initiated when the first author was on Sabbatical at Thomas J. Watson IBM Research Center, and was partially supported by the U.S.-Israel Binational Foundation, grant no. 86-00243/1. 相似文献
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