共查询到20条相似文献,搜索用时 31 毫秒
1.
Andreas Maurer 《Random Structures and Algorithms》2006,29(2):121-138
Following the entropy method this paper presents general concentration inequalities, which can be applied to combinatorial optimization and empirical processes. The inequalities give improved concentration results for optimal traveling salesmen tours, Steiner trees, and the eigenvalues of random symmetric matrices. © 2005 Wiley Periodicals, Inc. Random Struct. Alg., 2006 相似文献
2.
混合von Mises 模型的参数估计 总被引:1,自引:0,他引:1
有限混合von Mises模型在天文学、生物学、地理和医药等许多领域都有重要的应用.可是,不论样本量有多大,此模型的似然函数都是无界的.因此,参数的最大似然估计(MLE)是不相合的.我们发现,与混合正态模型一样,上述困难可以通过引入关于分布浓度参数的一个惩罚函数或对参数空间添加适当的约束来克服.在此文中,我们从理论上证明了这两种方法是可行的,相应的参数估计是强相合的,且是渐近有效的.我们还通过计算机模拟来探讨这些新方法在有限样本情况下的统计性质,并与现有的矩估计作了比较.结果发现,惩罚极大似然估计在均方误差方面表现最佳.最后我们还分析了一组实际数据,以进一步介绍新的估计方法. 相似文献
3.
Ning Ma Tongchao Lu Danping Yang 《Numerical Methods for Partial Differential Equations》2006,22(4):797-814
Miscible displacement of one incompressible fluid by another in a porous medium is modelled by a coupled system of two partial differential equations. The pressure equation is elliptic, whereas the concentration equation is parabolic but normally convection‐dominated. In this article, the collocation scheme is used to approximate the pressure equation and another characteristics collocation scheme to treat concentration equation. Existence and uniqueness of solutions of the algorithm are proved. Optimal order error estimate is demonstrated. © 2005 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2006 相似文献
4.
J. Pfanzagl 《Annals of the Institute of Statistical Mathematics》2003,55(1):95-110
Let
be a general family of probability measures,κ :
a functional, and
the optimal limit distribution for regular estimator sequences of κ. On intervals symmetric about 0, the concentration of
this optimal limit distribution can be surpassed by the asymptotic concentration of an arbitrary estimator sequence only forP in a “small” subset of
. For asymptotically median unbiased estimator sequences the same is true for arbitrary intervals containing 0. The emphasis
of the paper is on “pointwise” conditions for
, as opposed to conditions on shrinking neighbourhoods, and on “general” rather than parametric families. 相似文献
5.
Results are presented for the behavior of particle-laden gases in a moderate Reynolds number vertical channel down flow. The effects of mass loading on the gas-phase turbulence and particle concentration are studied. A direct numerical simulation including models of wall-particle interaction is conducted. It is confirmed that particle feedback causes the turbulence intensities to become more non-isotropic as the particle loading is increased. The particle concentration exhibits a maximum close to the wall and a slight increase in the middle of the channel. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
6.
Under the Bakry–Emery's -minoration condition, we establish the logarithmic Sobolev inequality for the Brownian motion with drift in the metric instead of the usual Cameron–Martin metric. The involved constant is sharp and does not explode for large time. This inequality
with respect to the -metric provides us the gaussian concentration inequalities for the large time behavior of the diffusion.
An erratum to this article can be found at 相似文献
7.
With the use of an analytical approach developed, the influence of distribution of a tangential load on the stress concentration
in uniaxially tensioned flat specimens of high-strength unidirectional composites near the grips of a testing machine is evaluated.
In view of singularity of the analytical solution derived at the points of discontinuity of boundary conditions, for estimating
the stress concentration, it is suggested to employ the averaged value of longitudinal stresses, which is calculated by means
of an improper integral across the thickness of a near-surface layer.
__________
Translated from Mekhanika Kompozitnykh Materialov, Vol. 42, No. 6, pp. 787–796, November–December, 2006. 相似文献
8.
Concentration of mass on convex bodies 总被引:2,自引:0,他引:2
G. Paouris 《Geometric And Functional Analysis》2006,16(5):1021-1049
We establish sharp concentration of mass inequality for isotropic convex bodies: there exists an absolute constant c > 0 such that if K is an isotropic convex body in
, then
for every
, where LK denotes the isotropic constant.
Research supported by a Marie Curie Intra-European Fellowship (EIF), Contract MEIF-CT-2005-025017. Part of this work was done
while the author was a Postdoctoral Fellow at the University of Athens under the EPEAEK program “Pythagoras II”.
Received: January 2006; Revision: March 2006; Accepted: March 2006 相似文献
9.
Dong Liang Hong Wang Robert C. Sharpley 《Numerical Methods for Partial Differential Equations》2006,22(6):1267-1288
In this article, we consider a single‐phase coupled nonlinear Stefan problem of the water‐head and concentration equations with nonlinear source and permeance terms and a Dirichlet boundary condition depending on the free‐boundary function. The problem is very important in subsurface contaminant transport and remediation, seawater intrusion and control, and many other applications. While a Landau type transformation is introduced to immobilize the free boundary, a transformation for the water‐head and concentration functions is defined to deal with the nonhomogeneous Dirichlet boundary condition, which depends on the free boundary function. An H1‐finite element method for the problem is then proposed and analyzed. The existence of the approximation solution is established, and error estimates are obtained for both the semi‐discrete schemes and the fully discrete schemes. © 2006 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2006 相似文献
10.
Michael Struwe 《Mathematische Zeitschrift》2007,256(2):397-424
For concentrating solutions weakly in H
2(Ω) to the equation on a domain with Navier boundary conditions the concentration energy is shown to be strictly quantized in multiples of the number . 相似文献
11.
This paper is concerned with the blow-up solutions of the Gross-Pitaevskii equation. Using the concentration compact principle
and the variational characterization of the corresponding ground state, we obtain the limiting profile of blow-up solutions
with critical mass in the corresponding weighted energy space. Moreover, we extend this result to small super-critical mass
case by the variational methods and scaling technique.
This work was supported by National Natural Science Foundation of China (Grant No. 10771151) and Scientific Research Fund
of Sichuan Provincial Education Department (Grant No. 2006A068) 相似文献
12.
Luk Poul 《Mathematical Methods in the Applied Sciences》2006,29(9):1035-1051
We study the long‐time behaviour of solutions to a quasilinear parabolic problem on a half‐line. The main result lies in showing the existence of a positive solution that converges to the travelling wave of solution to the stationary problem on the whole line. The main tools used here are the zero number theory and the concentration compactness principle. This result is a generalization of a result know for semilinear parabolic equations. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
13.
R. D. Maksimov S. Gaidukovs M. Kalnins J. Zicans E. Plume 《Mechanics of Composite Materials》2006,42(1):45-54
The preparation of a polymer nanocomposite by compounding an aqueous polymer emulsion with an aqueous dispersion of montmorillonite
clay is described. A styrene-acrylate copolymer emulsion and a purified native montmorillonite clay from Latvian deposits
are used. An X-ray diffraction analysis and differential scanning calorimetric thermograms are shown. Data on the influence
of montmorillonite concentration on the tensile stress-strain diagram, elasticity, yield stress, breaking stress, and ultimate
elongation of the processed nanocomposite material are obtained.
__________
Translated from Mekhanika Kompozitnykh Materialov, Vol. 42, No. 1, pp. 61–74, January–February, 2006. 相似文献
14.
Half-space problem of evaporation and condensation of a binary mixture of vapors is investigated on the basis of the linearized Boltzmann equation for hard-sphere molecules with the complete condensation condition. The problem is analyzed numerically by a finite-difference method, in which the complicated collision integrals are computed by the extension of the method proposed by Y. Sone, T. Ohwada, and K. Aoki [Phys. Fluids A 1 , 363 (1989)] to the case of a gas mixture. As a result, the behavior of the mixture is clarified not only at the level of the macroscopic quantities but also at the level of the velocity distribution function. In addition, accurate formulas of the temperature, pressure, and concentration jumps caused by the evaporation and condensation are constructed for arbitrary values of the concentration of the background reference state by the use of the Chebyshev polynomial approximation. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
15.
M. P. Fateev 《Theoretical and Mathematical Physics》2006,149(2):1519-1526
Based on the balance equation, we consider the diffusion problem on a hyperlattice with randomly distributed inaccessible
sites. Using diagram methods, we find a self-consistent expression for the configurationally averaged Green’s function in
the coherent potential approximation. We show that this approach is applicable in a broad range of concentrations of accessible
sites. Using this approximation, we find the exact asymptotic form of the static diffusion coefficient for a low concentration
of blocked sites. This allows making good estimates of the percolation threshold in the random-site diffusion problem on an
arbitrary hyperlattice.
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Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 149, No. 2, pp. 252–261, November, 2006. 相似文献
16.
Victor Ostrik 《Geometric And Functional Analysis》2008,17(6):2005-2017
We classify semisimple module categories over the tensor category of representations of quantum SL(2).
Received: May 2006, Revised: December 2006, Accepted: December 2006 相似文献
17.
Chèze Nathalie Poggi Jean-Michel Portier Bruno 《Statistical Inference for Stochastic Processes》2003,6(2):155-197
Starting from a variant of an estimator using marginal integration, this paper proposes partial and recombined estimators
for nonlinear additive regression models. Partial estimators are used for data analysis purposes and recombined estimators
are used to improve the estimation and prediction performances for small to moderate sample sizes. In the first part of the
paper, some simulations illustrate step-by-step the principle and the value of the proposed estimators, which are finally
applied to the analysis and prediction of ozone concentration in Paris area. In the second part of the paper, almost sure
convergence results as well as a multivariate central limit theorem and a test for partial additivity are provided.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
18.
In this paper we extend results from Semigroup Theory on existence and characterization of attractors in order to include
multivalued semigroups T(t) defined by generalized semiflows . In particular we show that, if is continuous, possesses a Lyapunov function, and has a global attractor which is maximal compact invariant, then = W
u
(Z()), where Z() is the stationary solutions set and W
u
(Z()) is the unstable set of Z(). We introduce the -attractor concept which does not enjoy any uniformity on time of attraction and we prove, under suitable conditions, that
the global -attractor is the set of asymptotic states described by Z().
Jacson Simsen is supported by CAPES-Brazil. 相似文献
19.
R. D. Maksimov S. Gaidukovs M. Kalnins J. Zicans E. Plume 《Mechanics of Composite Materials》2006,42(2):163-172
A variant of stepwise determination of the elastic characteristics of quasi-isotropic polymer-silicate nanocomposites with
randomly oriented platelike filler particles is considered. First, the elastic constants of transversely isotropic structural
elements with coplanarly placed filler particles are obtained, and then they are averaged over all spatial directions by using
the orientational averaging method. The characteristic features of the hierarchical structure of exfoliated and intercalated
nanocomposites are also considered. The concentration dependences of elastic constants of a nanocomposite based on a styrene-acrylate
copolymer and native montmorillonite clay are modeled, and the results obtained are compared with experimental data.
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Translated from Mekhanika Kompozitnykh Materialov, Vol. 42, No. 2, pp. 235–246, March–April, 2006. 相似文献
20.
G. Zeibig 《Applied Categorical Structures》2006,14(3):215-227
Let and be two monoids (algebras) in a monoidal category . Further let be a distributive law in the sense of [J. Beck, Lect. Notes Math., 80:119–140, 1969]; naturally yields a monoid . Consider a word in the symbols , , and . The first coherence theorem proved in this paper asserts that all morphisms coincide in , provided they arise as composites of morphisms which are -products of ’s ‘canonical’ structure morphisms, and of , , , , , , , and . Assume now that an object is endowed with both an -object structure , and an -object structure . Further assume that these two structures are compatible, in the sense that they naturally yield an -object . Let be a word in , , , and , which contains a single instance of , in the rightmost position. The second coherence theorem states that all morphisms coincide in , provided they arise as composites of morphisms which are -products of ’s ‘canonical’ structure morphisms, and of , , , , , , , , , and . 相似文献