基于统计物理的爆轰产物物态方程研究

用van der Waals等效单组分流体模型和Ross硬球微扰理论软球修正模型，计算爆轰气相产物的状态方程；用石墨相、金刚石相、类石墨液相和类金刚石液相４种相态描述凝聚成分，由Gibbs自由能最小确定不同状态下的凝聚产物相态.对爆轰产物混合系统采用Gibbs自由能最小原理，通过化学平衡方程组求解炸药爆轰产物系统的平衡组分，计算结果与Becker-Kistiakowsky-Wilson (BKW)和Lennard-Jones-Devonshire结果相近.使用该理论对炸药的爆轰参数做了预言，与BKW，Jo 关键词： 爆轰产物 物态方程 化学平衡方程组     

大粒子对高斯波束散射的数值模拟

基于广义米氏理论，精确的求解了球形粒子对高斯波束和平面波的散射，采用Matlab编程， 改进了计算方法，所能够计算的粒子的尺寸参数已突破80000. 给出了平面波与高斯波入射 时，均匀粒子以及镀层粒子的散射分布，比较了吸收粒子和非吸收粒子散射分布. 关键词： 广义米氏理论 高斯波束 光散射 波束因子     

高分子熔体和浓溶液流变性能的研究

基于多重缠结网络结构模型和高分子链上缠特点在流动中可进行动态解缠和再缠结的多重蠕动机理，用统计力学和动力学相结合的方法，分别了出了缠结链组的末端距分布函数；处于缠结状态下高分子链构象统计分布函数；受力下聚合物是性形变自由能和解除外力下高分子挤出体可回复性粘弹性形变自由能，提出了高分子挤出体可回复形变的粘弹性分子理论。推导出了的高分子熔体的回忆函数、简单剪切流下的本构方程和物料函数，并采用一种新的方法测定出物料的四种参数：η０、Ｇ＾０Ｎ、ｎ′和≤。对于高分子挤出体。可回复性粘弹性形变由快速弹性形变和慢速粘弹性形变两者组成，当把两种变量的复合结构参数－分子链的反式构象分数引入两种形变自由能表达式后，就从理论上得到了可回复形变量同挤出胀大比间的定量表达式，从而建立起一具有分子链结构参数的新的挤出胀大比方程，可回复形变     

高分子锚定的流体膜

将高分子自洽平均场理论和膜弹性理论结合起来研究高分子锚定流体膜体系，得到了高分子链热力学平衡浓度的分布和膜的形状.由于膜对高分子的不可穿透性，造成高分子可以实现的构象受到限制，导致高分子对膜施加不均匀的熵压，从而锚定点附近的膜弯离高分子，这些结果符合前人的理论分析和蒙特卡罗模拟的结果.此外，考察了膜和高分子链段之间的相互作用，高分子链长以及膜的弯曲刚性、张力对膜形变的影响. 关键词： 高分子 流体膜 自洽场理论 Helfrich膜弹性理论     

地层静温预测的非牛顿流体数学模型

根据热力学参数、泥浆参数及井筒结构参数等，先选定一个地层温度梯度进行计算，得出泥浆出口温度.将此计算值与实测温度值比较，按照比较结果再修正所选的地层温度梯度.如此反复，直到得出合理的地层温度梯度.在此基础上，从热力学及流体力学等有关方程出发， 经过推演得到井壁上温度随深度变化以及地层温度分布的数学模型.由于钻井过程中泥浆、 岩石及其温度场间是相互作用、相互影响的，这为研究热 流 固耦合渗流过程的理论与应 用提供了一种新的方法. 关键词： 温度梯度 非牛顿流体 数学模型     

正弦波导高频特性分析

对一种全金属慢波系统—–正弦波导的高频特性进行了理论分析.在用一系列相连矩形阶梯逼近余弦槽的基础上,对慢波结构进行了合理的区域划分,获得了各区域的场表达式.考虑槽区的高次驻波项,采用场匹配和导纳匹配相结合的方法,导出色散方程和耦合阻抗表达式.以应用于220 GHz行波管的正弦波导为例进行高频特性的数值求解,理论计算值与全三维电磁软件CST-MWS的仿真值符合良好.在此基础上,详细分析了尺寸参数变化对正弦波导高频特性的影响.     

固液相变过程最优控制数学定解分析及其算法

本文应用分布参数系统控制理论,采用变分法系统地分析,导出了二维固液相变传热过程最优控制问题的数学 定解条件,提出模型离散和数值求解方法,对共轭梯度最优控制算法进行适应性分析。     

静电六极装置电场分布的数值计算方法及在N2O分子转动态选择、取向中的应用

阐述求解极性分子转动态选择及取向静电六极装置中势能分布、电场分布的数值计算方法.为了获得电场分布公式,需通过数值迭代求解势能满足的Laplace方程,获取数值分布点,通过数值分布点,由待定系数的多级展开势能解析表达式进行最小二乘拟合获得势能分布公式,由势能对空间向量的微分获得电场分布.分子在六极电场中的运行轨迹采用经典Newton方程描述,并通过四阶龙格-库塔方法(Four Order Runge-Kutta Method)实现数值求解,其中能量处理采用量子力学方法.应用此方法给出静电六极装置的电场分布公式,运用获得的电场分布公式计算和讨论电场对极性分子N₂O的静电六极转动态选择、取向所带来的影响.     

透明基底表面双向反射分布函数及粗糙度特性研究

采用双向反射分布函数定量分析透明基底表面粗糙度,考虑到透明基底第二个界面的影响,从不透明基底双向反射分布函数入手,推导了实际测量的透明基底表面双向反射分布函数的表达式.依据此理论提出了通过分别测量两个表面的散射强度来联立求解透明基底实际表面反射分布函数和表面粗糙度谱的新方法.并将此结果与用原子力显微镜测量所获得的结果进行了比较,两者吻合较好.     

基于解析法的超导发电机磁场分析与结构优化

混合型高温超导发电机采用高温超导带材作励磁材料,结构上与传统电机有较大的不同,设计方法也不尽相同.本文基于傅里叶变换将超导发电机的励磁集中绕组等效为沿转子圆周正弦分布的激励源,建立了超导发电机磁场分析模型.对电机气隙磁场分布进行了求解,并分析了不同绕组张角时气隙磁密波形中的谐波含量.通过参数化分析,研究了不同环境屏、转子的尺寸对电机功率密度的影响.采用有限元法对磁场求解结果进行了验证,结果一致性较好.研究结果表明,励磁绕组张角会对电机气隙磁密波形产生影响,合理设置超导发电机环境屏及转子结构,可以提高超导发动机的功率密度.     

高分子凝胶体积相变中的氢键作用

我们把关联模型(association models)推广应用到高分子凝胶体系,研究高分子与溶剂分子间的氢键和溶剂分子与溶剂分子间的氢键在高分子凝胶体积相变中的作用.首先通过分析凝胶体积分数与温度的关系发现,由于两种氢键作用,随着温度变化高分子凝胶出现连续、不连续体积相变,结果表明在体积相变过程中两种氢键都起着重要作用.其次,对不同氢键分数条件下的旋节线的研究发现,对于高分子凝胶体积相变中出现的UCST和LCST(上临界共溶温度和下临界共溶温度)现象也是由于高分子与溶剂分子间氢键和溶剂分子与溶剂分子间氢键共同作用的结果.     

Determination of the adsorbed layer thickness of polystyrene on glass surface by viscosity measurements to the extremely dilute concentration region

A newly developed theory regarding solute adsorption effect in viscometry of a polymer solution is reviewed and extended for determining the adsorbed layer thickness of polystyrene on a glass surface in viscosity measurements. This theory can adequately describe the concentration dependence of the viscosity of a polymer solution measured by glass capillary viscometer to the extremely dilute concentration region. Using this theory, both the free polymer chains in solution and the adsorbed polymer chain on the viscometer inner wall surface can be characterized. Examples are given for the characterization of six polystyrene samples with different molar masses by measuring their solution viscosity in benzene.     

高分子梯度溶液吸声机理的研究

制备了高分子均匀溶液和梯度溶液,并在声管中测试其声衰减性能.实验结果表明,高分子梯度溶液的声衰减效果明显优于(即大于)相应的均匀溶液的声衰减.根据连续分层介质中声波传播理论建立了计算高分子梯度溶液声衰减的数学模型.计算结果与实验结果一致.由实验和理论分析结果得出了高分子梯度溶液的梯度吸声机理,即多次反射、多次吸收,最终将声能转化为热能.     

CdSe/ZnSe量子点在油水两相体系下的聚合物包覆相转移及其光谱表征

采用油水两相溶液体系,借助于双亲聚合物包覆实现了CdSe/ZnSe核壳结构量子点自油相到水相的相转移。油水两相中的聚合物包覆与已经报道的均相溶液中聚合物包覆量子点的方法不同,包覆过程在油水两相界面处完成,有效地减少了聚合物缠绕引起的量子点团聚,实现了聚合物对量子点的无团聚单分散包覆。透射电镜和激光粒度分析仪对聚合物包覆量子点的表征结果表明获得的水溶性量子点具有良好的分散性,均一的水力尺寸。吸收和发射光谱表明聚合物包覆过程对量子点的发射峰位和峰型没有引起明显的改变,维持了较高的量子产率。通过荧光微区成像技术成功实现了对人IgG蛋白的特异性检测,证实这种方法获得的聚合物包覆量子点具有较好的与生物分子偶联的功能化基团,适合于生物学标记应用。     

On the lattice theory,free volume theory,and effective volume theory of the thermodynamics of polymer solutions

The lattice theory [1, 2] of the thermodynamics of polymer solutions introduced in the early 1940s has been very useful for qualitatively explaining the state of polymer chains in solution. However, the model also contained unreasonable postulations. On this Flory stated in his book published in 1953 [3], “The adoption of a lattice scheme is not in itself a necessarily hazardous idealization. The succeeding postulate, namely, that the same lattice may be used to describe the configurations of both pure components and of the solution, is a much more serious one from the standpoint of application to real solutions. It requires (among other things) that the geometry of the two molecular species be virtually identical”. Further discussion is given under the heading “Approximations and Limitations of the Lattice Treatment”, where another important limitation is stated by the closing comment: “of importance here is the realization that the theory as developed so far is inappropriate, generally speaking, for dilute polymer solutions” [4].     

Tunable nonlinear viscoelastic "focusing" in a microfluidic device

In this Letter we describe a novel method for tunable viscoelastic focusing of particles flowing in a microchannel. It is proposed that some elasticity, inherently present in dilute polymer solutions, may be responsible for highly nonuniform spatial distribution of flowing particles across the channel cross section, yielding their "focusing" in the midplane of the channel. A theory based on scaling arguments is presented to explain the lateral migration and is found to be in a very good agreement with the experimental observations. It was found that, in agreement with the theoretical prediction, the particles would have different spatial distribution depending on their size and rheology of the suspending medium. We demonstrate how the viscoelastic focusing can be precisely controlled by proper rheological design of the carrier solution.     

Propagation and relaxation of tension in stiff polymers

We present a unified theory for the longitudinal dynamic response of a stiff polymer in solution to various external perturbations (mechanical excitations, hydrodynamic flows, electrical fields, temperature quenches, etc.) that can be represented as sudden changes of ambient/boundary conditions. The theory relies on a comprehensive analysis of the nonequilibrium propagation and relaxation of backbone stresses in a wormlike chain. We recover and substantially extend previous results based on heuristic arguments. New experimental implications are pointed out.     

线性多烯分子的共振拉曼光谱

线性多烯分子是重要的光电材料,它还具有光采集、 光防护、 防癌、 抗癌功能,也是物理学、 化学理论研究的理想分子。 共振拉曼光谱是研究线性多烯分子最有力的工具。 本文总结了线性多烯分子共振拉曼光谱的特征及其与分子结构的关系,包括：电子光谱(紫外-可见吸收光谱)、 拉曼光谱的性质及与外场的关系;电子能隙对碳碳原子振动的调制作用;给出几个实验结果：温度降低、 溶剂密度增加、 溶液浓度降低等会使线性多烯分子结构有序增加,π电子能隙减小,使紫外-可见吸收光谱红移;π电子离域扩展,有效共轭长度增加,拉曼活性提高,拉曼光谱红移,拉曼截面增加。 振幅模型是研究线性多烯分子较理想的模型。     

Electro-optical properties of dilute solutions of flexible molecules ; the wormlike chain model

A theory of propagation and scattering of light in dilute solutions of flexible chain molecules is developed. The solvent is represented as a continuous isotropic dielectric medium. The polymer molecules are modelled as dielectric objects which may have an anisotropic dielectric tensor. The theory, applied to the wormlike chain model, represents the polymer molecules as flexible cylinders of constant cross section and with an isotropic internal dielectric constant. The increment in the refractive index of the solution and the isotropic and anisotropic light scattering intensities due to the presence of the chain molecules are derived. The numerical results of our model for the depolarization ratio as a function of the contour length and the persistence length of the polymer and of the refractive index of the solvent are presented and compared with the corresponding results for the popular bond additive approximation (BAA). It is found that the differences between our model and this approximation are due to the neglect of intramolecular dipole-induced dipole interactions in the BAA.     

Polymer chain elasticity in the presence of a topological obstacle

The theory of high elasticity of polymer networks is developed under the assumption that each subchain is situated near a topological obstacle having the form of an infinite straight line, which cannot be crossed by the subchain. The statistics of a polymer chain in the presence of such an obstacle is considered using the well-known results of Edwards, Prager and Frisch, and Saito and Chen. It is shown that qualitative features of the stress-strain curves under uniaxial extension-compression obtained using the present approach correspond to those known from the experiments. However, quantitatively the deviations from the classical high elasticity theory appear to be too small.