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61.
Liping Liu Dominic P. Clemence Ronald E. Mickens 《Numerical Methods for Partial Differential Equations》2011,27(4):767-785
This study focuses on a contaminant transport model with Langmuir sorption under nonequilibrium conditions. The numerical instabilities of the standard finite difference schemes including the upwind method are investigated. By using the nonstandard finite difference method, a better finite difference model is constructed. The numerical simulation on a specific system configuration proves the advantages of the new finite difference model. © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 27: 767–785, 2011 相似文献
62.
Murat Sari Gürhan Gürarslan Asuman Zeytinoğlu 《Numerical Methods for Partial Differential Equations》2011,27(5):1313-1326
In this article, up to tenth‐order finite difference schemes are proposed to solve the generalized Burgers–Huxley equation. The schemes based on high‐order differences are presented using Taylor series expansion. To establish the numerical solutions of the corresponding equation, the high‐order schemes in space and a fourth‐order Runge‐Kutta scheme in time have been combined. Numerical experiments have been conducted to demonstrate the high‐order accuracy of the current algorithms with relatively minimal computational effort. The results showed that use of the present approaches in the simulation is very applicable for the solution of the generalized Burgers–Huxley equation. The current results are also seen to be more accurate than some results given in the literature. The proposed algorithms are seen to be very good alternatives to existing approaches for such physical applications. © 2010 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 27: 1313‐1326, 2011 相似文献
63.
Bo Wang Guang-an Zou Peng ZhaoQiang Wang 《Applied mathematics and computation》2011,217(12):5227-5235
In this paper, finite volume method is used to solve a one-dimensional parabolic inverse problem with source term and Neumann boundary conditions for the first time. Some advantages of this approach are developing difference schemes and maintaining certain properties of the physics of the problems, especially for the treatment of the source term and the unknown boundary conditions. Numerical results show that our method is more effective. 相似文献
64.
Wei LiuQimin Zhang 《Applied mathematics and computation》2011,218(8):3973-3980
In general, most of stochastic age-structured system of three species do not have explicit solutions, thus numerical approximation schemes are invaluable tools for exploring their properties. The aim of this paper is to investigate the convergence of numerical approximation solution to the true solution for stochastic age-structured system of three species. 相似文献
65.
Sorin G. Gal 《Applied mathematics and computation》2011,218(6):2944-2951
In the recent years the extension of linear positive operators from real to complex domain is one of the interesting area of research. In this context, we present the exact order of simultaneous approximation and Voronovskaja kind results with quantitative estimate for a new type of complex Durrmeyer operator (different from those previously studied), attached to analytic functions in compact disks. In this way, we put in evidence the overconvergence phenomenon for this kind of Durrmeyer operator, namely the extensions of approximation properties with exact quantitative estimates, from the real interval [1/3, 2/3] to compact disks in the complex plane. 相似文献
66.
Alexander Arhangel'skii 《Topology and its Applications》2011,158(2):215-222
Some new classes of pseudoopen continuous mappings are introduced. Using these, we provide some sufficient conditions for an image of a space under a pseudoopen continuous mapping to be first-countable, or for the mapping to be biquotient. In particular, we show that if a regular pseudocompact space Y is an image of a metric space X under a pseudoopen continuous almost S-mapping, then Y is first-countable. Among our main results are Theorems 2.5, 2.11, 2.12, 2.13, 2.14. See also Example 2.15, Corollary 2.7, and Theorem 2.18. 相似文献
67.
杨奇祥 《数学物理学报(B辑英文版)》2011,(4):1517-1534
If we use Littlewood-Paley decomposition, there is no pseudo-orthogonality for Ho¨rmander symbol operators OpS m 0 , 0 , which is different to the case S m ρ,δ (0 ≤δ < ρ≤ 1). In this paper, we use a special numerical algorithm based on wavelets to study the L p continuity of non infinite smooth operators OpS m 0 , 0 ; in fact, we apply first special wavelets to symbol to get special basic operators, then we regroup all the special basic operators at given scale and prove that such scale operator’s continuity decreases very fast, we sum such scale operators and a symbol operator can be approached by very good compact operators. By correlation of basic operators, we get very exact pseudo-orthogonality and also L 2 → L 2 continuity for scale operators. By considering the influence region of scale operator, we get H 1 (= F 0 , 2 1 ) → L 1 continuity and L ∞→ BMO continuity. By interpolation theorem, we get also L p (= F 0 , 2 p ) → L p continuity for 1 < p < ∞ . Our results are sharp for F 0 , 2 p → L p continuity when 1 ≤ p ≤ 2, that is to say, we find out the exact order of derivations for which the symbols can ensure the resulting operators to be bounded on these spaces. 相似文献
68.
本文研究了单位球上F(p,q,s)空间到βμ空间的加权Cesàro算子的有界性和紧性问题.利用泛函分析与多复变的方法,获得了单位球上F(p,q,s)空间到βμ空间的加权Cesàro算子为有界算子和紧算子的充要条件. 相似文献
69.
This paper deals with the numerical modeling of transient mechanical waves in linear viscoelastic solids. Dissipation mechanisms are described using the generalized Zener model. No time convolutions are required thanks to the introduction of memory variables that satisfy local-in-time differential equations. By appropriately choosing the relaxation parameters, it is possible to accurately describe a large range of materials, such as solids with constant quality factors. The evolution equations satisfied by the velocity, the stress, and the memory variables are written in the form of a first-order system of PDEs with a source term. This system is solved by splitting it into two parts: the propagative part is discretized explicitly, using a fourth-order ADER scheme on a Cartesian grid, and the diffusive part is then solved exactly. Jump conditions along the interfaces are discretized by applying an immersed interface method. Numerical experiments of wave propagation in viscoelastic and fluid media show the efficiency of this numerical modeling for dealing with challenging problems, such as multiple scattering configurations. 相似文献
70.
刘德金 《纯粹数学与应用数学》2011,27(2):151-157
覆盖方法的应用在粗糙集理论研究中越来越受到重视,其中拓扑空间的子集关于子基的内部和闭包两个概念尤为重要.在由它们导入的关于子基的开集,闭集的基础上,给出了拓扑空间关于子基的紧致性概念,并研究它的性质,得到一般拓扑空间中紧致性的一种推广. 相似文献