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一致椭圆扩散的一个比较定理及其应用
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作者 王梓坤 张新生 李占柄 《中国科学(A辑)》 CSCD 1993年第11期1121-1129,共9页
本文得到了一致椭圆扩散与Brown运动之间的一个比较定理,利用此比较定理我们给出了一致椭圆扩散象集的Packing测度的上界估计及其样本轨道的整体连续模的上界估计。
关键词 一致椭圆扩散 Packing测度 连续模
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多参数一致椭圆扩散的一个比较定理及其应用
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作者 张新生 《科学通报》 EI CAS CSCD 北大核心 1992年第19期1732-1735,共4页
本文主要讨论多参数一致椭圆扩散的若干样本轨道性质。我们首先建立了多参数一致椭圓扩散与多参数布朗运动之间的一个比较定理,在此基础上进一步得到了多参数一致椭圆扩散象集的Hausdorff维数与Packing维数的上界,以及样本轨道连续模的... 本文主要讨论多参数一致椭圆扩散的若干样本轨道性质。我们首先建立了多参数一致椭圓扩散与多参数布朗运动之间的一个比较定理,在此基础上进一步得到了多参数一致椭圆扩散象集的Hausdorff维数与Packing维数的上界,以及样本轨道连续模的上界估计。为了记号上的简单,这里只叙述两参数的情形,所有结果均可推广到N参数(N>2)的情形。 展开更多
关键词 椭圆扩散 PACKING维数 H-维数
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各向异性沥青防水膜鼓泡扩散机理 被引量:1
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作者 张文超 李志刚 郝培文 《中外公路》 北大核心 2015年第1期228-233,共6页
目前,用于混凝土桥面或建筑物屋面的防水体系一般都是采用基于正交各向异性沥青膜;其中,苯乙烯-丁二烯-苯乙烯共聚物(SBS)和无规聚丙烯(APP)聚合物改性沥青膜应用范围比较广,但存在自底向上的压力导致膜下形成鼓泡。该文通过弹性力学建... 目前,用于混凝土桥面或建筑物屋面的防水体系一般都是采用基于正交各向异性沥青膜;其中,苯乙烯-丁二烯-苯乙烯共聚物(SBS)和无规聚丙烯(APP)聚合物改性沥青膜应用范围比较广,但存在自底向上的压力导致膜下形成鼓泡。该文通过弹性力学建模与试验来研究它的扩散机理。为了研究复杂平面应力状态下SBS膜的材料性能,通过双轴拉伸试验对聚合物改性沥青防水卷材(PBM)的正交各向异性力学性能进行试验。然后,对测得的应力-应变数据进行分析,确定纵向和横向的材料特性常数。在混凝土板上进行鼓泡试验,通过控制PBM和混凝土板之间的压力来进行鼓泡扩散机理研究。结果发现:鼓泡在纵向和横向的扩散比值与纵向和横向弹性模量的比值相当。根据PBM的正交各向异性材料特性,通过对椭圆形鼓泡扩散过程观察,提出一个新的模型确定椭圆鼓泡的扩散能量。 展开更多
关键词 PBM防水膜 正交各向异性材料 双轴拉伸试验 椭圆鼓泡扩散
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巷道注浆加固浆液扩散数值模拟
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作者 高明中 井欢庆 陈雨雪 《安徽理工大学学报(自然科学版)》 CAS 2017年第2期6-9,共4页
通过注浆能较好地解决开挖后巷道修复和长期稳定的问题,然而注浆参数的确定往往需要借助工程类比。为探索注浆浆液扩散过程和注浆位置、注浆压力之间的关系,采用数值模拟软件UEDC对不同的注浆位置以及注浆压力,进行了数值模拟分析。通... 通过注浆能较好地解决开挖后巷道修复和长期稳定的问题,然而注浆参数的确定往往需要借助工程类比。为探索注浆浆液扩散过程和注浆位置、注浆压力之间的关系,采用数值模拟软件UEDC对不同的注浆位置以及注浆压力,进行了数值模拟分析。通过注浆数值模拟试验,分析了注浆孔位置和注浆压力等因素对浆液扩散半径的影响规律,并将模拟试验结果应用于巷道注浆工程设计与施工中。结果表明:浆液扩散的形状随注浆位置的变化而变化;注浆压力对浆液扩散面积有一定影响。调压注浆是提高注浆效果的有效措施。 展开更多
关键词 巷道 注浆加固 浆液 扩散椭圆 调压注浆
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带漂移扩散过程的一个比较定理
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作者 张新生 《汕头大学学报(自然科学版)》 1994年第1期20-25,共6页
本文得到了带漂移的一致椭圆扩散过程与带漂移的布朗运动间的一个比较定理,推广了[2]中的结果,并且所用的证明方法与[2]有本质的不同。
关键词 椭圆扩散 比较定理 布朗运动
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液化和压缩气体半球形扩散模型集的构建和应用 被引量:2
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作者 王林元 林红 《安全与环境学报》 CAS CSCD 北大核心 2017年第2期601-607,共7页
国内外液化和压缩气体的泄漏爆炸事故屡见不鲜,针对其性质和短时间近地面扩散的特点,总结、修正和扩展了瞬时泄漏下的平均半球形扩散模型。对于连续泄漏,利用数学积分理论建立了静风下的半球形扩散模型。接着对有风时的情况进行建模推导... 国内外液化和压缩气体的泄漏爆炸事故屡见不鲜,针对其性质和短时间近地面扩散的特点,总结、修正和扩展了瞬时泄漏下的平均半球形扩散模型。对于连续泄漏,利用数学积分理论建立了静风下的半球形扩散模型。接着对有风时的情况进行建模推导,将风速和气体自身扩散速度进行矢量合成,得到了半椭球形扩散和半椭圆锥与1/4椭球体组合扩散下气体的质量浓度和质量浓度变化趋势。最后用实例验证了该模型的先进性。该模型集能较好地反映液化和压缩气体泄漏后不同泄漏情况、时间、近地面区域和风速下的扩散浓度空间分布及其动态变化过程,为事故后果预估和应急救援决策提供参考。 展开更多
关键词 安全工程 液化和压缩气体 平均半球形扩散 半椭球形扩散 椭圆锥与1/4椭球体的组合扩散
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Existence of Positive Solutions for a Class of Degenerate and Nondegenerate Stable Diffusion Models
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作者 张彦肖 《Chinese Quarterly Journal of Mathematics》 CSCD 2000年第3期50-56,共7页
This paper is concerned with a class of degenerate and nondegenerate stable diffusion models.By using the upper and lower solution method and Schauder fixed point principle,the author studies the existence of positive... This paper is concerned with a class of degenerate and nondegenerate stable diffusion models.By using the upper and lower solution method and Schauder fixed point principle,the author studies the existence of positive solutions for these stable_diffusion models under some conditions. 展开更多
关键词 weak upper and lower solutions elliptic system positive solution
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Rational Form Solitary Wave Solutions and Doubly Periodic Wave Solutions to (1+1)-Dimensional Dispersive Long Wave Equation 被引量:1
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作者 WANGQi CHENYong ZHANGHong-Qing 《Communications in Theoretical Physics》 SCIE CAS CSCD 2005年第6期975-982,共8页
In this work we devise an algebraic method to uniformly construct rational form solitary wave solutions and Jacobi and Weierstrass doubly periodic wave solutions of physical interest for nonlinear evolution equations.... In this work we devise an algebraic method to uniformly construct rational form solitary wave solutions and Jacobi and Weierstrass doubly periodic wave solutions of physical interest for nonlinear evolution equations. With the aid of symbolic computation, we apply the proposed method to solving the (1+1)-dimensional dispersive long wave equation and explicitly construct a series of exact solutions which include the rational form solitary wave solutions and elliptic doubly periodic wave solutions as special cases. 展开更多
关键词 elliptic equation rational expansion method rational form solitary wavesolutions rational form jacobi and weierstrass doubly periodic wave solutions symboliccomputation (1+1)-dimensional dispersive long wave equation
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On the Behavior of Certain Turing System
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作者 Janpou Nee Hsi-Chuan Huang 《Journal of Mathematics and System Science》 2012年第6期393-397,共5页
The generalized maximum principle of Lou and Ni is extended from elliptic equations to parabolic equations. By this result, one can show that the system of fugal mycelia has a global attractor if the diffusion coeffic... The generalized maximum principle of Lou and Ni is extended from elliptic equations to parabolic equations. By this result, one can show that the system of fugal mycelia has a global attractor if the diffusion coefficient D = 0 and the solution blows up ifD= 0. The method of linearization is applied to derive the existence of Hopfs bifurcation which is the signature of instability of Turing system. The increasing of the size of the attractor and the existence of Hopf' s bifurcation indicate that there is a threshold that initiates the instability. 展开更多
关键词 Global attractor Hopf's bifurcation blow-up solution periodic solutions.
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Further Extended Jacobi Elliptic Function Rational Expansion Method and New Families of Jacobi Elliptic Function Solutions to (2+1)-Dimensional Dispersive Long Wave Equation
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作者 ZHANG Yuan-Yuan WANG Qi ZHANG Hong-Qing 《Communications in Theoretical Physics》 SCIE CAS CSCD 2006年第2期199-206,共8页
In this paper, a further extended Jacobi elliptic function rationM expansion method is proposed for constructing new forms of exact solutions to nonlinear partial differential equations by making a more general transf... In this paper, a further extended Jacobi elliptic function rationM expansion method is proposed for constructing new forms of exact solutions to nonlinear partial differential equations by making a more general transformation. For illustration, we apply the method to (2+1)-dimensionM dispersive long wave equation and successfully obtain many new doubly periodic solutions. When the modulus m→1, these sohitions degenerate as soliton solutions. The method can be also applied to other nonlinear partial differential equations. 展开更多
关键词 doubly periodic solution soliton solution (2+1)-dimensional dispersive long wave equation
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Limit Theorems of a Class of Super-Uniformly Elliptic Diffusions
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作者 唐加山 《Journal of Mathematical Research and Exposition》 CSCD 北大核心 2002年第3期345-350,共6页
In this paper, we investigate super-uniformly elliptic diffusions {Xt,t ≥ 0} with its branching mechanism given by ψ(z) = γz1+β(0 < ≤ 1), and, when the initial value X0(dx) is one kind of invariant measures of... In this paper, we investigate super-uniformly elliptic diffusions {Xt,t ≥ 0} with its branching mechanism given by ψ(z) = γz1+β(0 < ≤ 1), and, when the initial value X0(dx) is one kind of invariant measures of the underlying processes, we show that if dimension d satisfies βd ≤ 2, then the random measures Xt will converge to the null in distribution and if βd > 2, then Xt will converge to a nondegenerative random measure in the same sense. 展开更多
关键词 uniformly elliptic diffusion superproces limit theorem.
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Two-dimensional finite element model to study calcium distribution in astrocytes in presence of excess buffer 被引量:5
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作者 Brajesh Kumar Jha Neeru Adlakha M. N. Mehta 《International Journal of Biomathematics》 2014年第3期137-147,共11页
In this paper a finite element model is developed to study cytosolic calcium concen- tration distribution in astrocytes for a two-dimensional steady-state case in presence of excess buffer. The mathematical model of c... In this paper a finite element model is developed to study cytosolic calcium concen- tration distribution in astrocytes for a two-dimensional steady-state case in presence of excess buffer. The mathematical model of calcium diffusion in astrocytes leads to a boundary value problem involving elliptical partial differential equation. The model con- sists of reaction-diffusion phenomena, association and dissociation rates and buffer. A point source of calcium is incorporated in the model. Appropriate boundary conditions have been framed. Finite element method is employed to solve the problem. A MATLAB program has been developed for the entire problem and simulated to compute the numer- ical results. The numerical results have been used to plot calcium concentration profiles in astrocytes. The effect of ECTA, BAPTA and aCa influx on calcium concentration distribution in astrocytes is studied with the help of numerical results. 展开更多
关键词 Ca2+ profile BUFFER finite element method.
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