时滞差分方程的吸引性

本文给出了时滞差分方程x_n+1=x_nf(x_n,x_n-1),n=0,1,…解的全局吸引性的一个新的充分条件;作为应用,部分解决了G.Ladas的一个猜想.     

二维分数布朗运动(FBM)随机粗糙面电磁散射的基尔霍夫近似

采用二维FBM分形函数来模拟二维实际粗糙面,利用基尔霍夫近似给出了FBM粗糙面的电磁散射场和散射截面的计算公式.数值计算并分析了散射截面与分维、特征长度及入射频率的关系,并与高斯相关分布和指数相关分布粗糙面的散射结果做了比较 关键词： FBM粗糙面 分形 电磁散射 基尔霍夫近似     

金属表面荧光增强的物理增强机制

具有特殊形貌及构型的表面(如金属薄膜)能够使位于其邻近的荧光分子的荧光信号得到增强, 这种现象被称之为表面增强荧光(Surface Enhanced Fluorescence, SEF)。有关表面增强荧光效应的研究探讨已有许多报道,并先后提出了多种增强机理以试图理解和解释观测到的实验现象。本文将在总结归纳已有机理研究的基础上,从物理学的角度出发分析理解局域场增强、能量转移以及辐射衰减速率增加等理论模型,并对衬底表面与荧光分子之间的间距变化对增强效果的影响进行探讨。     

相互作用对玻色气体热力学性质及稳定性的影响

根据由赝势法得到的非理想玻色气体的自由能和状态方程，研究了相互作用对凝聚温度的影响.从热力学角度揭示了存在引力作用时定压热容量、等温压缩系数、定压膨胀系数的反常热力学特性.研究了引力作用下玻色气体系统的不稳定性，给出了不稳定性的温度判据和粒子数密度判据. 关键词： 相互作用 玻色气体 热力学性质 不稳定性判据     

一类具无穷时滞泛函微分方程的周期解

讨论具有无穷时滞中立型泛函微分方程$ \frac{\rm d}{{\rm d}t}\left(x(t)-\int_{-\infty}^{0}g(s,x(t+s)){\rm d}s\right) =A(t,x(t))x(t)+f(t,x_t)$的周期解问题,利用重合度理论中的延拓定理得到了周期解的存在性和唯一性条件;特别地,当$g(s,x)\equiv 0, A(t,x)=A(t)$时, 给出了存在唯一稳定周期解的条件.     

Z箍缩丝阵负载区域的似稳态磁场分布

 将负载区域的电流（丝阵电流、阴极板电流、阳极板电流和回流柱电流）离散成电流线或电流面等电流微元,根据毕奥-萨伐尔定律,计算所有电流微元在指定场点的磁场,再通过叠加给出该点的总磁场。研究结果发现:在丝阵外围区域,仅由丝阵电流所产生的磁场偏离无限长直导线磁场公式的值,但全部电流所产生的总磁场与公式给出的值很接近。同时,研究了不同负载结构参数下的磁场分布,结果表明：增加丝根数有助于减小单根丝表面的局部磁场,改善丝阵外围磁场分布的均匀性。     

The Hard Rod Fluid in a Uniform Gravitational Field

Abstract

The system of hard rods in an external, uniform gravitational field is studied and exact expressions obtained for the partition functions, and the one- and two-particle distributions. In principle all higher order distributions can be exactly expressed as finite sums and the Laplace transforms of the one-particle density and pressure for a semi-infinite system are reducible to single integrals. Limiting cases of weak field and small rod diameters are examined. In the former case, these results agree with Percus and Lebowitz's local density expansion. In the latter case, corrections to the barometric pressure and density laws are obtained. Finally some mathematical difficulties involved in the calculation of the virial expansion and distribution of roots of the grand partition function are mentioned.     

Thermal Conductivity of CuSbSe2 and CuBiSe2 in the Solid and Liquid State

Abstract

Thermal Conductivity of CuSbSe₂ and CuBiSe₂ have been studied in the solid and liquid state in a wide range of temperatures. Measurements of thermal conductivity were carried out using the concentric cylinder method which is based on the flow of heat through a cylindrical wall.     

The Determination of the Titre of Ascorbic Acid Standard Solutions

Abstract

A new method for the determination of the titre of ascorbic acid standard solutions employing potassium dichromate as a primary standard has been developed. In a pyrophosphate medium, the pyrophosphate complex of divalent manganese is oxidized by dichromate to the pyrophosphate complex of tervalent manganese; the latter oxidizes o-tolidine reversibly with formation of the corresponding quinonediimine, which is visually titrated by the ascorbic acid standard solution.     

Conventional processes and membrane technology for carbon dioxide removal from natural gas:A review

Membrane technology is becoming more important for CO 2 separation from natural gas in the new era due to its process simplicity,relative ease of operation and control,compact,and easy to scale up as compared with conventional processes.Conventional processes such as absorption and adsorption for CO 2 separation from natural gas are generally more energy demanding and costly for both operation and maintenance.Polymeric membranes are the current commercial membranes used for CO 2 separation from natural gas.However,polymeric membranes possess drawbacks such as low permeability and selectivity,plasticization at high temperatures,as well as insufficient thermal and chemical stability.The shortcomings of commercial polymeric membranes have motivated researchers to opt for other alternatives,especially inorganic membranes due to their higher thermal stability,good chemical resistance to solvents,high mechanical strength and long lifetime.Surface modifications can be utilized in inorganic membranes to further enhance the selectivity,permeability or catalytic activities of the membrane.This paper is to provide a comprehensive review on gas separation,comparing membrane technology with other conventional methods of recovering CO 2 from natural gas,challenges of current commercial polymeric membranes and inorganic membranes for CO 2 removal and membrane surface modification for improved selectivity.