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《数学的实践与认识》2013,(24)
固井环空微间隙气体窜槽现象直接影响固井质量与油田生产,准确地描述固井环空微间隙气体窜槽的流动规律是有效控制气体窜槽的核心与"瓶颈"问题.从微观粒子运动角度出发,基于格子Boltzmann方法建立了固井环空微间隙气体粒子流动模型.选取大庆油田某区块计算模拟不同环空压差下微间隙内气体粒子流动速度分布规律,计算结果揭示了固井气窜气体粒子在微环间隙内流动的本质,为后续固井气窜问题的研究开辟新的思路. 相似文献
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空间的微重力给晶体生长提供了一个消除自然对流、由纯扩散控制的生长环境,为提高晶体质量创造了条件,引起晶体生长研究人员的关注.中国科学院物理研究所和日本东京大学电子工程系合作,1992年在中国第14颗返回式卫星上成功地生长了一根φ6 mm×30 mm外形完整的GaSb单晶.对空间生长的晶体的研究显示:晶体在空间生长部分无Ⅰ类生长条纹,表明晶体生长时既无自然对流也没有Marangoni对流.位错密度测定表明,晶体在空间生长期间熔体未与坩埚器壁接触时生长的晶体位错密度接近于零,而熔体与坩埚器壁接触后位错密度迅速增高.详细叙述了该晶体的生长和研究,分析了微重力对晶体生长的影响,并对空间晶体生长的发展提出看法. 相似文献
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模拟井筒是用于模拟油田井下高温高压环境的实验装置,为高温高压厚壁容器.基于热力学及大涡模拟(LES)理论,建立了模拟井筒温度场物理方程.基于热弹性力学理论,建立了热应力物理方程.采用投影法求解温度场控制方程,采用梯形法数值积分求解热应力控制方程,给出了控制方程的离散格式.通过虚拟密度法对流固耦合传热进行求解,根据应力叠加原理对模拟井筒热应力和压应力及其耦合作用进行了数值求解分析.研究结果表明:设计壁厚最小值为0.18 m的模拟井筒,强度能够满足在400℃加热环境、内部加压220 MPa工作参数下进行高温高压实验.通过实验验证了所建立的数学模型与数值求解方法的正确性,为高温高压厚壁容器设计提供了理论依据. 相似文献
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将描述多组分系统的复合混合物理论与微极性连续介质力学理论相结合,建立了描述微极性多组分多孔介质材料的混合物理论.假定系统由多组分的微极性弹性固体和多组分微极性粘性流体组成.给出由混合物理论建立的系统的平衡方程.依据热力学第二定律以及本构假设建立了系统的本构方程,并使场方程闭合.为考虑固相的压缩性,在液相自由能函数中引入液相体积分数作为内变量,得到动力相容条件,用以限制固、液两相界面压力差的变化.最后,基于线性化理论得到线性化的本构方程和场方程,建立了考虑介质微极性的热-水力-力学组分输运模型.此理论框架可以运用到可变形多孔介质中污染物、药物以及农药输运等问题中,所得到的微极性多组分多孔介质系统的闭合场方程经退化后,可变为固、流相都为单一组分的多孔介质系统场方程,它与Eringen得到的结果一致. 相似文献
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对流扩散方程作为偏微分运动方程的分支,在流体力学、气体动力学等领域有着重要应用.为解决对流扩散方程难以通过解析法得到解析解的难题,采用二阶一致3点积分(Quadratically Consistent 3-Point Integration,简称QC3)提高无网格法的计算效率,通过对积分点上形函数导数的修正,改善无网格法的精度和收敛性.本文将QC3无网格法拓展到对流扩散方程问题中,时域离散采用广义特征线Galerkin法,空间离散采用QC3法.数值结果表明,应用QC3无网格法得到的对流扩散问题数值解与解析解十分接近,验证了QC3无网格法解决对流扩散问题的可行性. 相似文献
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One of the most fundamental problems in theoretical biology is to explain the mechanisms by which patterns and forms are created in the'living world. In his seminal paper "The Chemical Basis of Morphogenesis", Turing showed that a system of coupled reaction-diffusion equations can be used to describe patterns and forms in biological systems. However, the first experimental evidence to the Turing patterns was observed by De Kepper and her associates(1990) on the CIMA reaction in an open unstirred reactor, almost 40 years after Turing's prediction. Lengyel and Epstein characterized this famous experiment using a system of reaction-diffusion equations. The Lengyel-Epstein model is in the form as follows 相似文献
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Kunyang Wang Feng Dai 《分析论及其应用》2007,23(1):50-63
As early as in 1990, Professor Sun Yongsheng, suggested his students at Beijing Normal University to consider research problems on the unit sphere. Under his guidance and encouragement his students started the research on spherical harmonic analysis and approximation. In this paper, we incompletely introduce the main achievements in this area obtained by our group and relative researchers during recent 5 years (2001-2005). The main topics are: convergence of Cesaro summability, a.e. and strong summability of Fourier-Laplace series; smoothness and K-functionals; Kolmogorov and linear widths. 相似文献
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Pankaj Mathur 《分析论及其应用》2006,22(2)
In this paper, we study the explicit representation and convergence of (0, 1; 0)-interpolation on infinite interval, which means to determine a polynomial of degree ≤ 3n - 2 when the function values are prescribed at two set of points namely the zeros of Hn(x) and H′n(x) and the first derivatives at the zeros of H′n(x). 相似文献
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We study a class of self-similar processes with stationary increments belonging to higher order Wiener chaoses which are similar to Hermite processes. We obtain an almost sure wavelet-like expansion of these processes. This allows us to compute the pointwise and local Hölder regularity of sample paths and to analyse their behaviour at infinity. We also provide some results on the Hausdorff dimension of the range and graphs of multidimensional anisotropic self-similar processes with stationary increments defined by multiple Wiener–Itô integrals. 相似文献
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ZHENG ShiJun 《分析论及其应用》2004,20(3)
Schr(o)dinger operator is a central subject in the mathematical study of quantum mechanics.Consider the Schrodinger operator H = -△ V on R, where △ = d2/dx2 and the potential function V is real valued. In Fourier analysis, it is well-known that a square integrable function admits an expansion with exponentials as eigenfunctions of -△. A natural conjecture is that an L2 function admits a similar expansion in terms of "eigenfunctions" of H, a perturbation of the Laplacian (see [7], Ch. Ⅺ and the notes), under certain condition on V. 相似文献
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It is considered the class of Riemann surfaces with dimT1 = 0, where T1 is a subclass of exact harmonic forms which is one of the factors in the orthogonal decomposition of the spaceΩH of harmonic forms of the surface, namely The surfaces in the class OHD and the class of planar surfaces satisfy dimT1 = 0. A.Pfluger posed the question whether there might exist other surfaces outside those two classes. Here it is shown that in the case of finite genus g, we should look for a surface S with dimT1 = 0 among the surfaces of the form Sg\K , where Sg is a closed surface of genus g and K a compact set of positive harmonic measure with perfect components and very irregular boundary. 相似文献
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Yuxian Zheng 《分析论及其应用》2006,22(2):136-140
In this paper, we study the commutators generalized by multipliers and a BMO function. Under some assumptions, we establish its boundedness properties from certain atomic Hardy space Hb^p(R^n) into the Lebesgue space L^p with p 〈 1. 相似文献
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H. H. Cuenya M.D. Lorenzo C. N. Rodriguez 《分析论及其应用》2007,23(2):162-170
In this paper we study best local quasi-rational approximation and best local approximation from finite dimensional subspaces of vectorial functions of several variables. Our approach extends and unifies several problems concerning best local multi-point approximation in different norms. 相似文献
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Journal of the Operations Research Society of China Special issue on Operations Research in Healthcare Management 下载免费PDF全文
《运筹学学报》2014,(3)
正Guest Editors:Hong Chen,Shanghai Jiao Tong University,Shanghai,China Guohua Wan,Shanghai Jiao Tong University,Shanghai,China David Yao,Columbia University,New York,USA Scope:Healthcare delivery worldwide has been fraught with high cost,low efficiency and poor quality of patient care service.For the field of operations research(OR),healthcare offers some of the biggest challenges as well as best opportunities in 相似文献