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排序方式: 共有719条查询结果,搜索用时 15 毫秒
1.
In this paper we consider a wavelet algorithm for the piecewise constant collocation method applied to the boundary element solution of a first kind integral equation arising in acoustic scattering. The conventional stiffness matrix is transformed into the corresponding matrix with respect to wavelet bases, and it is approximated by a compressed matrix. Finally, the stiffness matrix is multiplied by diagonal preconditioners such that the resulting matrix of the system of linear equations is well conditioned and sparse. Using this matrix, the boundary integral equation can be solved effectively. 相似文献
2.
Bernard Bialecki 《Numerical Algorithms》1994,8(2):167-184
Cyclic reduction and Fourier analysis-cyclic reduction (FACR) methods are presented for the solution of the linear systems which arise when orthogonal spline collocation with piecewise Hermite bicubics is applied to boundary value problems for certain separable partial differential equations on a rectangle. On anN×N uniform partition, the cyclic reduction and Fourier analysis-cyclic reduction methods requireO(N
2log2
N) andO(N
2log2log2
N) arithmetic operations, respectively. 相似文献
3.
Katrin Leschke 《Annals of Global Analysis and Geometry》1997,15(1):51-69
On every isoparametric submanifold M a connection with parallel second fundamental form is constructed geometrically such that M is an orbit of an s-representation if and only if the connection is a canonical one. If the rank of M is greater than one this connection is in case of homogeneity the canonical connection of the reductive decomposition given
by the orbit of s-representation.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
4.
In this paper, we present a new algorithm to estimate a regression function in a fixed design regression model, by piecewise
(standard and trigonometric) polynomials computed with an automatic choice of the knots of the subdivision and of the degrees
of the polynomials on each sub-interval. First we give the theoretical background underlying the method: the theoretical performances
of our penalized least-squares estimator are based on non-asymptotic evaluations of a mean-square type risk. Then we explain
how the algorithm is built and possibly accelerated (to face the case when the number of observations is great), how the penalty
term is chosen and why it contains some constants requiring an empirical calibration. Lastly, a comparison with some well-known
or recent wavelet methods is made: this brings out that our algorithm behaves in a very competitive way in term of denoising
and of compression. 相似文献
5.
6.
P. S. Szczepaniak 《Journal of Optimization Theory and Applications》1989,63(3):459-468
This paper deals with dynamic systems described by nonlinear differential-difference equations of retarded type. The problem considered is to determine the initial function and certain system parameters which minimize a given cost functional. A computational method is presented and some convergence results are given. Numerical examples of linear and nonlinear systems are also included. 相似文献
7.
ONBAHADURASYMPTOTICEFFICIENCYINASEMIPARAMETRICREGRESSIONMODELLIANGHUA(梁华);CHENGPING(成平)(InstituteofSystemsScience,theChineseA... 相似文献
8.
Summary Based on a thorough knowledge of the actual system precision significance testing of the primary eigen values, resulting from principal component analysis of the two-dimensional data array of HPLC with photodiode-array detection, is a powerful means to uncover unresolved chromatographic peaks. The implementation of this chemometric technique for assuring peak homogeneity and results showing the efficiency for two-component peaks in regard to spectral characteristics, chromatographic resolution and absorbance ratio of the investigated compounds are presented. 相似文献
9.
Spectroscopy and Structure of Sol-Gel Systems 总被引:1,自引:0,他引:1
Sol-gel derived glasses may differ from conventional melt-quenched glasses owing to the peculiar microstructures existing at the gel state, such that, even after gel densification, some differences may remain in their composition and molecular structure.This paper discusses structural characteristics of thin film oxide gels and glasses, with a special emphasis on SiO2-TiO2 based systems, which are of particular interest for sol-gel integrated optics applications. Short range structure aspects are discussed based on infrared, X-ray photoemission and X-ray photoabsorption spectroscopies. The chemical homogeneity of sol-gel materials is evaluated, based on X-ray photoemission and nuclear magnetic resonance spectroscopies, dealing in particular with the issue of homo- vs. heterocondensation. Finally, some microstructural features of sol-gel derived films are analyzed, namely the relationship between infrared absorption and porosity and the structure of nanocrystalline sol-gel films, based on grazing incidence X-ray diffraction and micro-Raman spectroscopy. The types of structural information obtainable by each different technique are compared in detail. 相似文献
10.
Mach Nguyet Minh 《Mathematische Nachrichten》2014,287(11-12):1341-1362
We show that under some appropriate assumptions, every weak solution (e.g. energetic solution) to a given rate‐independent system is of class SBV, or has finite jumps, or is even piecewise C1. Our assumption is essentially imposed on the energy functional, but not convexity is required. 相似文献