Natural convection of air in a square cavity: A bench mark numerical solution

Details are given of the computational method used to obtain an accurate solution of the equations describing two-dimensional natural convection in a square cavity with differentially heated side walls. Second-order, central difference approximations were used. Mesh refnement and extrapolation led to solutions for 10³?Ra?10 ⁶ which are believed to be accurate to better than 1 per cent at the highest Rayleigh number and down to one-tenth of that at the lowest value.     

一类半线性抛物边值问题的最大值原理

文中构造了一类具有Dirichlet或Neumann边界条件的半线性抛物方程u_t=Δu+f(x,u,q,t) (q=|u|^2)的解的一个辅助函数，对其使用Hopf最大值原理和黎曼几何理论，从而获得了该函数的最大值原理，据此原理获得了梯度q和解u的估计.     

Uniqueness for the BBGKY hierarchy for hard spheres in one dimension

We prove that the stationary BBGKY hierarchy for an infinite system of hard spheres in one dimension has a unique solution for all densities, within a symmetry class that pertains to either a fluid array or to a perfect crystalline array. The solution is shown to correspond to the uniform fluid, which is the only equilibrium state of the infinite system. The proof is subject to the recursion relation for the correlation functions found by Salsburg, Zwanzig, and Kirkwood, which we show exactly reduces the infinite hierarchy to a pair of coupled equations. A brief discussion is given of the existence of multiple solutions of an approximate BBGKY equation.     

任意流场中颗粒运动方程的通解(英)

给出了任意流场中颗粒运动方程的无因次和线性微分方程形式．估计了颗粒运动方程中的一些相关项．借助于一些数学推导和处理，求得了比线性颗粒运动方程的通解．     

利用二维核磁共振法研究粉防已碱的溶液构象

本文利用二维核磁共振的质子NOE谱、四极矩二维谱、异核化学位移相关谱研究了粉防已碱的溶液构象,并确定了五条谱线的归属.     

On the periodic solution of N–Dimensional Stochastic Population Models *

Two n species stochastic population models with periodic coefficients are studied. Some sufficient conditions for the existence of asymptotically stable periodic solution process are obtained respectively     

Infrared Spectra of Tris(ethylendiamine) Cobalt(III) Complex Ion in Solid State and Dissolved in Light and Heavy Water

In recent years, at least two groups^1,2 have developed programmes for combined conformational and vibrational analysis of complicated molecular systems. A version of one of these systems² is currently being adapted for work on coordination complexes. In such work experimental data are needed, and they stem almost exclusively from x-ray structural determinations, and infrared spectra of solids. Most calculational schemes so far deal with isolated molecules, and as one objective of the calculations is to provide thermodynamic functions, which, as far as coordination complexes are concerned, are measured in aqueous solution, we consider it necessary to compare some key properties of the substances as measured in the solid state and in solution. In particular, we want to investi- gate the extent to which internal vibrations are independent of the surroundings of the complexion.     

在非光滑区域中含有透射条件的椭圆方程边值问题

本文研究非光滑区域Ω上的椭圆型方程透射问题。在Ｓｏｂｏｌｅｖ空间中，通过变分的形式，引进弱解的讨论，证明了解的存在、唯一和正则性质。     

集值映射最优化问题的严有效解集的连通性及应用

本文对集值映射最优化问题引入严有效解的概念．证明了当目标函数为锥类凸的集值映射时,其目标空间里的严有效点集是连通的;若目标函数为锥凸的集值映射时,其严有效解集也是连通的．作为应用,讨论了超有效解集的连通性．     

ABS/clay nanocomposites obtained by a solution technique: Influence of clay organic modifiers

Acrylonitrile-butadiene-styrene (ABS) polymer/clay nanocomposites were produced using an intercalation-adsorption technique from polymer in solution: polymer/clay suspensions were subjected to ultrasonic processing to increase the effectiveness of mixing. Several kinds of organically modified layered silicates (OMLS) were used to understand the influence of the surfactant nature on the intercalation-exfoliation mechanism. We show that only imidazolium-treated montmorillonite (DMHDIM-MMT) is stable at the processing temperature of 200 °C, used for hot-pressing, whereas alkyl-ammonium modified clays show significant degradation.The morphology of ABS based polymer nanocomposites prepared in this work was characterized by means of wide angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM). Dynamic-mechanical analysis (DMA) was used to determine the storage modulus and damping coefficient as a function of temperature, and to investigate the correlations between mechanical properties and morphology of the nanocomposites. The thermal stability was assessed by means of thermogravimetric analysis (TGA). DMA and TGA show that the nanocomposites based on imidazolium-modified clay out-perform the nanocomposites based on quaternary-ammonium-modified clays in terms of mechanical properties and thermal stability.