地震作用下水库坝体与水体相互作用数值模拟

地震作用下水库坝体受迫振动,推动坝后水体波动,造成水体动压作用于坝体,形成坝-水耦合作用,影响坝体安全.为了评估坝体振动引起的水面波动及坝体所受动水荷载作用,建立坝体动边界条件下的不可压水体运动数学模型,模拟了地震波作用下的坝后水体波动和动力荷载.结果 表明,在忽略坝体自身弹性变形的条件下,地震作用下坝体激发的水体表面...     

汶川地震后中国及邻区地震活动趋势——地震能量释放特征的“振荡类比”研究

根据欧亚地震带东段地质构造和地震活动特征,选取中国及邻区地震区域,对1897—2008年发生的824次震级Ｍ_s≥60地震的年度释放能量进行滤波和系统分析.结果显示,地震能量释放特征表现为周期性衰减振荡.通过振荡特征分析和计算,从理论上预测中国及邻区长期和中短期强震活动形势.计算结果表明,所选区域内大陆板块地震活跃时间应持续1537 a,如果从1897年开始,即到2050年结束.这一理论结果与中国两千多年历史地震资料分析结论一致,也为我国的地震活跃期持续150 a左右 关键词： 中国大陆及邻区 年度地震能量 强震活动预测 振荡类比     

Source mechanism model for ground motion simulation

A simple analytical model for computing ground motion in a layered half-space due to a buried seismic source is presented in this paper. The buried earthquake source is represented as a distribution of double couples varying in time as a ramp function on the fault plane. The analysis is simplified by first decoupling the governing equations into P-SV and SH problem by a coordinate transformation in the frequency-wave number domain. These two problems are solved separately and the final solution is obtained by the sum of solutions of these individual problems. Explicit expressions for ground motion in a layered half-space due to an impulsive double couple are derived. In the sequel, Green’s function for the displacement field in an infinite medium is also presented. The developed source mechanism model is also demonstrated by simulating ground motion for the Kucth earthquake (M_w = 7.7) of 26th January 2001.     

Interaction of faults under slip‐dependent friction. Non‐linear eigenvalue analysis

We analyse the evolution of a system of finite faults by considering the non‐linear eigenvalue problems associated to static and dynamic solutions on unbounded domains. We restrict our investigation to the first eigenvalue (Rayleigh quotient). We point out its physical significance through a stability analysis and we give an efficient numerical algorithm able to compute it together with the corresponding eigenfunction. We consider the anti‐plane shearing on a system of finite faults under a slip‐dependent friction in a linear elastic domain, not necessarily bounded. The static problem is formulated in terms of local minima of the energy functional. We introduce the non‐linear (static) eigenvalue problem and we prove the existence of a first eigenvalue/eigenfunction characterizing the isolated local minima. For the dynamic problem, we discuss the existence of solutions with an exponential growth, to deduce a (dynamic) non‐linear eigenvalue problem. We prove the existence of a first dynamic eigenvalue and we analyse its behaviour with respect to the friction parameter. We deduce a mixed finite element discretization of the non‐linear spectral problem and we give a numerical algorithm to approach the first eigenvalue/eigenfunction. Finally we give some numerical results which include convergence tests, on a single fault and a two‐faults system, and a comparison between the non‐linear spectral results and the time evolution results. Copyright © 2004 John Wiley & Sons, Ltd.     

控制两相邻结构地震动响应的Maxwell模型流体阻尼器优化参数研究

运用被动连接单元减小相邻结构的振动被证明是一种行之有效的手段。将两相邻结构简化为两单自由度体系,用Maxwell模型模拟连接两相邻结构的流体阻尼器,分别导出了在地面白噪声激励下主结构平均振动能量最小或两相邻结构总平均振动能量最小这两个控制目标下流体阻尼器优化参数的一般表达式,该优化参数仅与两相邻结构的相对自振频率和相对质量有关,也讨论了两相邻结构的相对自振频率和相对质量对控制效果的影响。最后,运用具有不同相对参数的三类相邻结构在El Centro 1940 NS地震波作用下时域响应的数值结果说明了这种被动优化流体阻尼器能够非常有效地减小在地震作用下两相邻结构的振动响应。     

Multisim仿真软件在三相电源相序检测中的应用

介绍一种EDA(电子设计自动化)仿真软件M u ltis im 2001应用在三相电源相序检测的仿真方法;建立三相交流电源,设计相序检测电路;调用仿真软件提供的测试工具和仪表进行仿真,根据仿真结果进行分析和观测三相电源相序的变化规律.     

用Mathcad2001进行希克斯和斯勒茨基价格效应分析(一)

利用 Mathcad2 0 0 1 ,据实例条件作出了西方经济学中的希克斯和斯勒茨基价格效应分析 (包括收入效应和替代效应 ) ,并据此分析画出了两种价格效应分析的准确图形 ,展示了 Mathcad在经济学理论中的用途 ,以期引起同仁对 Mathcad在经济学乃至其它社会科学中应用价值的高度重视 .     

用Mathcad2001进行希克斯和斯勒茨基价格效应分析(二)

利用 Mathcad2 0 0 1 ,据实例条件在上文作出了价格效应分析的基础上 ,求出了三条具有重要意义的非线性的马歇尔需求曲线、希克斯需求曲线和斯勒茨基需求曲线的方程 ,并画出了两种价格效应分析和三条需求曲线的准确图形 ,展示了 Mathcad在经济学理论中的用途 ,以期引起同仁对 Mathcad在经济学乃至其它社会科学中应用价值的高度重视     

Possible triggering of solar activity to big earthquakes (Ms ≥ 8) in faults with near west-east strike in China

This paper studies the relationship between solar activity and big earthquakes (Ms≥8) that occurred in China and western Mongolia. It is discovered that the occurrence dates of most of the big earthquakes in and near faults with west-east strike are close to the maximum years of sunspot numbers, whereas dates of some big earthquakes which are not in such faults are not close to the maximum years. We consider that it is possibly because of the appearance of many magnetic storms in the maximum years of solar activity. The magnetic storms result in anomalies of geomagnetic field and then produce eddy current in the faults gestating earthquake with near west-east strike. Perhaps the gestated big earthquakes occur easily since the eddy current heats the rocks in the faults and therefore decreases the shear resistant intensity and the static friction limit of the rocks.     

Influence of Inhomogeneity on Critical Behavior of Earthquake Model on Random Graph

We consider the earthquake model on a random graph. A detailed analysis of the probability distribution of the size of the avalanches will be given. The model with different inhomogeneities is studied in order to compare the critical behavior of different systems. The results indicate that with the increase of the inhomogeneities, the avalanche exponents reduce, i.e., the different numbers of defects cause different critical behaviors of the system. This is virtually ascribed to the dynamical perturbation.