Experimental and calculated results showed that creep proceeded in two phases and andrade theory could simulate appropriately the creep constitutive relations of pmma in single dimension . furthermore , the accumulation theory in low stress and the strain - rigidification theory in the first phase of creep could also describe approximately the constitutive relations of pmma 实验与计算结果表明，蠕变明显地分为两阶段， andrade理论能很好地模拟pmma材料在恒定应力作用下的一维蠕变型本构关系；陈化理论在低应力水平下及应变硬化理论在蠕变第一阶段也可近似地描述pmma的本构关系。
Firstly , we introduced the significance and development , and theory of fingerprinting technology in a whole and analyzed that the lower bound on the fingerprint length needed approximately grows logarithmically in the number of uses and linearly in the number of pirates in theory 本文首先对数字指纹技术的意义、发展、理论等方面作了全面的概述；并从理论上分析了理想情况下所需指纹长度的下界近似地随着码集可容纳用户数对数增加，随着抗合谋用户数线性增加的原理。
Abstract : with the increasing of suspension bridge ? s span , the gravity stiffness of suspension cable itself is more important than vertical deflection resistance stiffness of stiffening girder which is serviced for the whole structure . in order to provide more knowledge of gravity stiffness of suspension cable , in this paper , gravity stiffness of suspension cable is formulated briefly and theoretically in case of ignoring the existing of the stiffening girder . the deformation and internal force of suspension cable can be calculated approximately in this way 文摘:随着悬索桥跨度的增大，加劲梁的竖向抗弯刚度提供给整个桥跨结构的刚度仅占次要地位，而悬索自身的重力刚度却占有重要的作用.为加深对重力刚度的进一步认识，笔者对特大跨度的悬索桥的重力刚度进行简要的理论推导，在忽略加劲梁存在的情况下，可近似地计算悬索桥的变形和内力
Following is our main work and important conclusions : ( 1 ) the question of energy spectrum hardening . we used the klein - nishina ' s differential scatter formula , meanwhile utilize the thaler progression to spread out , and neglected the high - power , and then we deduced a theoretical formula of correction of energy spectrum hardening 其主要工作和结论如下： （ 1 ）对x射线能谱硬化问题，把klein - nishina微分散射方程，利用泰勒级数展开，在忽略高次项的情形下，近似地推导出了能谱硬化修正公式。
We adopted here the high accuracy method of using the expansions in orthogonal functions along the normal direction and the effective algebraic mapping to deal with the problem in the infinite region . the initial solutions of two - dimensional harmonic waves are given by landau expansion , and the mean - flow - distortion is calculated by the approximation equation . we can get the initial conditions of ts wave and sub - harmonic wave in the c - type instability by linear pse method 运用landau展开给出了二维谐波的初始解、通过求解线性pse而得到ts波和c型亚谐扰动的初始站值、以及近似地模拟初始站的均流变形值,以此为初始条件,并结合迭代-预估校正方法来实现非线性pse的求解和推进,详细地研究了非平行边界层三维扰动c型失稳过程。
