大型钢结构变形测试方法的研究与实践

介绍了精密全站仪进行结构测试的原理和方法,通过对某大型游泳跳水馆钢结构网架在张拉和加载试验中的变形测量实践,证明其具有作业简便、能够全面反映结构变形情况之优点,且精度较高,成果可靠。     

On the Occurence of Extreme Events in Long-term Correlated and Multifractal Data Sets

We review recent studies of the statistics of return intervals (i) in long-term correlated monofractal records and (ii) in multifractal records in the absence (or presence) of linear long-term correlations. We show that for the monofractal records which are long-term power-law correlated with exponent γ, the distribution density of the return intervals follows a stretched exponential with the same exponent γ and the return intervals are long-term correlated, again with the same exponent γ. For the multifractal record, significant differences in scaling behavior both in the distribuiton and correlation behavior of return intervals between large events of different magnitudes are demonstrated. In the absence of linear long-term correlations, the nonlinear correlations contribute strongly to the statistics of the return intervals such that the return intervals become long-term correlated even though the original data are linearly uncorrelated (i.e., the autocorrelation function vanishes). The distribution density of the return intervals is mainly described by a power law.     

板块运动规律梳理及其源动力实验计算研究

洋中脊是大洋的胚胎,从洋中脊为地堑式中央裂谷的形态特征来看,大洋是拉张应力的产物,因此必须依据大陆漂移造成海底被动扩张这一结论来分析研究板块运动的动力源问题.大陆漂移的方向是有规律的,根据世界大洋年龄图等资料进行逆推,还原不同阶段的洋陆展布状态,可以看出,白垩纪以来南半球大陆分解向北运动、北半球大陆分解向南运动,大陆在...