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51.
A transient molecular network model is built to describe the nonlinear viscoelasticity of polymers by considering the effect
of entanglement loss and regeneration on the relaxation of molecular strands. It is an extension of previous network theories.
The experimental data on three thermoplastic polymers (ABS, PVC and PA6) obtained under various loading conditions are used
to test the model. Agreement between the theoretical and experimental curves shows that the suggested model can describe successfully
the relaxation behavior of the thermoplastic polymers under different loading rates by using relatively few relaxation modes.
Thus the micromechanism responsible for strain-rate dependence of relaxation process and the origin of nonlinear viscoelasticity
may be disclosed.
The project supported by the National Natural Science Foundation of China and Doctorial Fund 相似文献
52.
53.
54.
教师课堂教学质量的多元统计分析 总被引:3,自引:0,他引:3
应用多元统计分析中的聚类分析法和主成分分析法对教师高等数学的课堂教学质量进行了统计分析,通过对数据的聚类分析结果提出教师应注重启发性教学并善于引导学生解决实际问题.同时利用主成分分析将原先众多的评价指标用三个指标代替,为进一步提高教学质量提供科学的依据. 相似文献
55.
利用球磨法制备石墨-六角氮化硼微晶混合物,并在6.1 GPa、800~1 500 ℃条件下与水进行高压反应,以便研究用水作触媒合成B-C-N三元化合物的可能性。通过对反应产物的XRD、XPS谱分析发现:高压下随着温度的升高,反应产物中出现再结晶石墨,其晶化程度逐渐提高;但没有出现再结晶六角氮化硼,也未出现立方氮化硼。在球磨不充分条件下,石墨-六角氮化硼混合物的XRD谱没有完全弥散,它们与水高压反应时,能观察到石墨与立方氮化硼分别结晶的现象,但都没有形成B-C-N晶化结构。 相似文献
56.
Jiangen Huang Guiqin Zhang Yuanhe Huang Decai Fang Deqing Zhang 《Journal of magnetism and magnetic materials》2006
A one-dimensional (1D) silver (I) complex of nitronyl nitroxide with fairly strong antiferromagnetic interaction, in which the metal ions are diamagnetic, is investigated by means of the ab initio crystal orbital method based on the density functional theory. The calculated values of the magnetic coupling constant (J) are close to the experimental measured J value in the periodic system. The magneto-structural correlation reveals that the existence of an antiferromagnetic coupling pathway along nitronyl nitroxide units via silver (I) ion in this system. The spin population distribution also shows the existence of spin delocalization along the ONCNO–Ag–ONCNO, which affords a rational interpretation for the antiferromagnetic interaction mechanism. 相似文献
57.
58.
Xi Nian FANG Jian Hua WANG 《数学学报(英文版)》2006,22(6):1819-1824
In this paper, we study the extension of isometries between the unit spheres of normed space E and C(Ω). We obtain that any surjective isometry between the unit spheres of normed space E and C(Ω) can be extended to be a linear isometry on the whole space E and give an affirmative answer to the corresponding Tingley's problem (where Ω be a compact metric space). 相似文献
59.
In this paper, we study a micro‐macro model for polymeric fluid. The system involves coupling between the macroscopic momentum equation and a microscopic evolution equation describing the combined effects of the microscopic potential and thermofluctuation. We employ an energetic variation procedure to explore the relation between the macroscopic transport of the particles and the induced elastic stress due to the microscopic structure. For the initial data not far from the equilibrium, we prove the global existence and uniqueness of classical solutions to the system. © 2006 Wiley Periodicals, Inc. 相似文献
60.
A mistake concerning the ultra LI-ideal of a lattice implication algebra is pointed out, and some new sufficient and necessary conditions for an LI-ideal to be an ultra LI-ideal are given. Moreover, the notion of an LI-ideal is extended to MTL-algebras, the notions of a (prime, ultra, obstinate, Boolean) LI-ideal and an ILI-ideal of an MTL-algebra are introduced, some important examples are given, and the following notions are proved to be equivalent in MTL-algebra: (1) prime proper LI-ideal and Boolean LI-ideal, (2) prime proper LI-ideal and ILI-ideal, (3) proper obstinate LI-ideal, (4) ultra LI-ideal.
This work was supported by the Zhejiang Provincial Natural Science Foundation of China (Grant No. Y605389) and K. C. Wong
Magna Fund in Ningbo University. 相似文献