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结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,分别计算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;受力下聚合物熔体粘弹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、 GN0、 n′和 a。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,当把两种形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,从而建立起一个具有分子链结构参数的新的挤出胀大比方程,可回复形变量同挤出条件（温度、挤出速率和量以及口模长径比不同的挤出机）和树脂结构特征（分子量及分布）的关系式以及在特殊情形下的简化表达式,并用几种高分子熔融体系的挤出胀大比和可回复性形变量的实验数据对理论进行验证,理论方程同实验数据较好的符合。     

An Area Modulus of Elasticity: Definition and Properties

A new modulus of elasticity is defined to be the ratio of an equibiaxial stress to the relative area change in the planes in which the stress acts. This area modulus of elasticity is intermediate in properties between Young's modulus and the bulk modulus. Expressions for the area modulus are computed in isotropic elasticity. A simple, convenient expression for the compliance tensor of transverse isotropy is found in terms of, amongst others, the longitudinal (axial) area modulus and this leads to a new, concise condition for positive definiteness of the compliance tensor. The limits of incompressibility, inextensibility and constant area are briefly considered. This revised version was published online in August 2006 with corrections to the Cover Date.     

带服务器的Flow Shop问题

经典的 Flow Shop问题是排序理论中一个得到广泛研究的问题. 本文研究的是带服务器的Flow Shop问题. 证明了 F2,S∥Cmax 是强 N P-C的 ,并构造了一个渐近比为 2的近似算法. 此外,还讨论了它的两种多项式可解的条件.     

四氟乙烯/偏氟乙烯乳液共聚反应的竞聚率测定

用亨利定律关联了四氟乙烯 (TFE) /偏氟乙烯 (VDF)乳液共聚合体系中的单体气相分压与其对应液相浓度间的关系 ,推导了用气相摩尔分数表示的共聚物组成方程式 .通过气相色谱和19F NMR分别测定了共聚反应前后气相单体组成和共聚物组成 ,用非线性回归法 (RREVM )计算TFE/VDF乳液共聚合反应表观竞聚率分别为γTFE=0 35和γVDF=0 6 3 .将实测的表观竞聚率代入共聚物组成方程计算共聚物组成与由19F NMR测定的结果一致 ,为进一步的工业放大试验提供科学依据     

Hydrophobically modified polyelectrolytes III. Reactivity ratio determination of FX14/AA,LA/AA and SA/AA

The reactivity ratios of three hydrophobic monomers, FX14, LA and SA, to hydrophilic monomer, acrylic acid (AA), were determined. For the fluorocarbon containing hydrophobic monomer FX14, elemental analysis was adopted to obtain the relative content of FX14 to AA. For two hydrocarbon monomers, ¹³C NMR was used. FR, KT linear method and EVM nonlinear method were applied in calculating reactivity ratios. It is found that the reactivity of LA and SA is lower than that of AA, for solution polymerization in cyclohexane. Whereas FX14 is more reactive than AA in benzene. Finally, the distribution of small amounts of these hydrophobic monomers along the polymeric chain is discussed and a random sequence is confirmed     

非线性再生散度模型的渐近性质

对非线性再生散度模型,给出了类似于Ｆａｈｒｍｅｉｒ＆Ｋａｕｆｍａｎｎ（１９８５）和Ｗｅｉ（１９９８）的正则条件．基于这些正则条件,证明了最大似然估计的存在性、强相合性和渐近正态性,推广了已有文献的工作．     

关于随机选择的一个强极限定理

本文利用似然比和区间剖分法研究相依Ｎ值随机变量序列选择的极限性质,得到关于赌博方法的一个强极限定理的若干推广。     

关于Steiner比猜想

本文所讨论的是Ｓｔｅｉｎｅｒ比猜想。全文共分两部分：第一部分包括历史回顾和对ｎ＝３,４,５三种情况对该猜想的正确性给出了简单的证明;第二部分则对于一般的ｎ给出了一个证明。     

Simultaneously Applying Multiple Mutation Operators in Genetic Algorithms

The mutation operation is critical to the success of genetic algorithms since it diversifies the search directions and avoids convergence to local optima. The earliest genetic algorithms use only one mutation operator in producing the next generation. Each problem, even each stage of the genetic process in a single problem, may require appropriately different mutation operators for best results. Determining which mutation operators should be used is quite difficult and is usually learned through experience or by trial-and-error. This paper proposes a new genetic algorithm, the dynamic mutation genetic algorithm, to resolve these difficulties. The dynamic mutation genetic algorithm simultaneously uses several mutation operators in producing the next generation. The mutation ratio of each operator changes according to evaluation results from the respective offspring it produces. Thus, the appropriate mutation operators can be expected to have increasingly greater effects on the genetic process. Experiments are reported that show the proposed algorithm performs better than most genetic algorithms with single mutation operators.     

Effects of unsymmetrical geometric confinements on depletion interactions in colloidal suspensions

The depletion interactions between two large-spheres immersed in a fluid of small spheres under unsymmetrical geometrical confinement are studied through the acceptance ratio method. The numerical results show that no matter whether the volume fraction is large or small, both the depletion potential and depletion force are affected by the presence of the two plates; the closer the two large spheres are to the plate, the larger the effects of the unsymmetrical confinements.