Characteristic fractional step finite difference method for nonlinear section coupled system

For the section coupled system of multilayer dynamics of fluids in porous media, a parallel scheme modified by the characteristic finite difference fractional steps is proposed for a complete point set consisting of coarse and fine partitions. Some tech- niques, such as calculus of variations, energy method, twofold-quadratic interpolation of product type, multiplicative commutation law of difference operators, decomposition of high order difference operators, and prior estimates, are used in theoretical analysis. Optimal order estimates in 12 norm are derived to show accuracy of the second order approximation solutions. These methods have been used to simulate the problems of migration-accumulation of oil resources.     

半正定两相驱动问题的多步有限体积方法及其理论分析

考虑多维半正定两相驱动方程的初边值问题,在非结构网格上构造多步的迎风有限体积格式,利用微分方程先验估计理论证明了格式的离散模形式的误差估计为D(△t~2 h),其中△t和h分别表示时空步长．数值算例进一步验证了格式的有效性．     

提高重整化群精度的一个尝试

以热逾渗分析散粒体导热率时,利用重整化群方法改变粗视化程度来定量地获得导热率的变化。实践表明这只有设法提高重整化群的精度才会有较好的结果。本文以逾渗转变为例,针对b=2的相关尺度变化方式,分别对二维和三维实空间的重整化变换进行了修正,导出了相应的重整化方程。计算精度有明显提高,计算结果与实验值更接近。     

GENERALIZED OPERATORS AND P（φ）2 QUANTUM FIELDS

In this paper by Sobolev imbedding theorem and characterization theorem of generalized operators the existence of P(φ)2 quantum fields as generalized operators is obtained and a rigorous mathematical interpretation of renormalization procedure is given under white noise theory.     

Transport properties in La0.7-xGdxSr0.3MnO3 system

The influence of Gd doping at La-site on the electrical transport properties and the colossal magnetoresistance of La0.7-xGdxSr0.3MnO3 (x = 0.00, 0.10, 0.15, 0.20, 0.30, 0.40, 0.50, 0.60, and 0.70) is studied. The experimental results indicate that the transport properties exhibit abnormal behavior under high doping condition. For x = 0.50, we find that a transition from metal to insulator occurs after the occurrence of insulator-metal transition near Tc, which seldom occurs in ABO3 structure. For samples x = 0.60 and 0.70, it exhibits insulator behavior far above Tc. These abnormal behaviors are attributed to different magnetic background, i.e. the system undergoes a transition from long range ferromagnetic order to the cluster-spin glass state and further to antiferromagnetic order.     

Pathwise Uniqueness of the Solutions toVolterra Type Stochastic DifferentialEquations in the Plane

In this paper we prove the pathwise uniqueness of a kind of two-parameter Volterra type stochastic differential equations under the coefficients satisfy the non-Lipschitz conditions. We use a martingale formula in stead of Ito formula, which leads to simplicity the process of proof and extends the result to unbounded coefficients case.     

两指标Poisson型随机微分方程的单调迭代方法

本文在一般满足通常性条件的概率空间中，利用单调迭代方法讨论了由Poisson点过程驱动的两指标随机微分方程的上下解。在系数满足非Lipschits条件下给出了两个解U（z)和V（z)使得方程的任意解x(z)有U（z)≤x(z)≤V(z).     

局部坐标有限分析法解材料非线性结构问题

本文首次将有限分析法应用于分析固体力学中的弹塑性问题,导出了二维全量理论弹塑性边值问题的计算格式。采用了局部坐标变换,使该方法能有效地用于求解某些几何形状较复杂的平面问题。算例表明,这一方法解非线性问题是有效的。     

碱土金属氧化物改性的HZSM-5表面酸性和苯、乙醇烷基化反应活性、选择性研究

用TPD、IR技术研究了MgO、CaO和BaO改性的HZSM-5表面酸性,并以苯、乙醇烷基化合成乙苯反应考察了催化剂的活性和选择性。结果表明,随着氧化物含量的增加,氨的TPD量下降,IR谱图上1550cm^-1(B酸)吸收峰减小,活性及选择性均下降(MgO含量为3%时选择性最高)。     

N-二茂铁亚胺的合成及螯合反应

合成了9个N-二茂铁亚胺化合物和2个双核配合物,合成方法简便,反应时间短,易于分离提纯,经元素分析、红外光谱、核磁共振及紫外光谱确定了结构。结果表明在缩合反应中,氨基二茂铁和芳伯胺的作用相同,产物结构类似。