Mass transfer and possible third-body effect on the period variations of the near-contact binary CN And

We present a period analysis of the near-contact binary CN And using all available times of light minima. It is revealed that the orbital period exhibits a long-term decrease as well as a small-amplitude cyclic oscillation. This result suggests that the secular period decrease at the rate of d P/dt =-1.4017 ×10~(-7) d yr~(-1) is caused by a combination of mass transfer and angular momentum loss due to magnetic braking. The periodic variation with an amplitude of A = 0.0036 d and a period of Pmod = 28.3542 yr should be rooted in the light-time effect of a third body, rather than cyclic magnetic activity.     

Investigation of damping in arch dam-water-foundation rock system of Mauvoisin arch dam

The overall damping of linear arch dam-water-foundation rock systems depends on the material damping of dam concrete, the material and radiation damping of semi-unbounded foundation rock, and the dam-water interaction. In this paper, the effective damping ratio of these factors is separately evaluated for Mauvoisin arch dam in Switzerland to quantitatively discuss their contributions, and to guide the damping selection in the numerical analysis. This paper also aims to investigate if the material and radiation damping of the foundation rock can be replaced by increasing the material damping of the dam to simplify numerical analysis models. The seismic responses of Mauvoisin arch dam are analyzed using the semi-unbounded and massless foundation models, respectively. The results show that the overall effective damping ratio of the system can be approximately expressed as the summation of the individual effective damping and thus the increased material damping of the dam can approximate the material and radiation damping of the semi-unbounded foundation rock.     

An improved method for estimating life losses from dam failure in China

Stochastic Environmental Research and Risk Assessment - A dam-break flood can cause catastrophic life losses due to the uncontrolled large amount of water. This paper aims to improve the estimation...     

Real-time dynamic hybrid testing for soil–structure interaction analysis

Simulating dynamic soil–structure interaction (SSI) problems is a challenge when using a shaking table because of the semi-infinity of soil foundations. This paper develops real-time dynamic hybrid testing (RTDHT) for SSI problems in order to consider the radiation damping effect of the semi-infinite soil foundation using a shaking table. Based on the substructure concept, the superstructure is physically tested and the semi-infinite foundation is numerically simulated. Thus, the response of the entire system considering the dynamic SSI is obtained by coupling the numerical calculation of the soil and the physical test of the superstructure. A two-story shear frame on a rigid foundation was first tested to verify the developed RTDHT system, in which the top story was modeled as the physical substructure and the bottom story was the numerical substructure. The RTDHT for a two-story structure mounted on soil foundation was then carried out on a shaking table while the foundation was numerically simulated using a lumped parameter model. The dynamic responses, including acceleration and shear force, were obtained under soft and hard soil conditions. The results show that the soil–structure interaction should be reasonably taken into account in the shaking table testing for structures.     

基于震源-河谷波场数值模拟的坝址地震动参数确定方法

针对目前高坝坝址地震动参数确定方法的一些不足,本文尝试了一种基于地震学理论的坝址区三维地震动场生成方法.基本思路是将地震学和工程学结合,针对设定地震,建立震源-传播介质-坝址峡谷场地数值模型,通过超大规模的数值计算,模拟地震波从发震断层破裂开始到坝址场地的物理传播过程,生成坝址区的三维地震动参数.与传统基于衰减关系的地震动参数确定方法相比,这一方法可以考虑震源机制、传播介质和坝址峡谷场地效应等三大要素的影响.对于特定的坝址,可以生成符合实际地质构造、区域岩体动力特性以及坝址峡谷地质地形条件的地震动荷载分布,具有针对性,为重大高坝枢纽工程遭遇极端地震荷载作用时的抗震安全性提供了一种新的分析手段.     

钙同位素地球化学综述

钙是主要的造岩元素之一,也是生物必需的元素之一,在地球各圈层广泛分布,因此研究钙同位素的地球化学行为有助于提高我们对各种地质过程的认识。特别的是,地表碳酸盐主要是以碳酸钙的形式存在,很大程度上决定了碳循环与钙循环是耦合的。因此,钙同位素是研究碳的再循环的重要示踪剂,可以直接提供深部碳循环的准确信息。和其他非传统稳定同位素体系一样,随着实验技术的进步及多接收电感耦合等离子体质谱(MC ICP MS)和热电离质谱(TIMS)的发展,钙同位素分析方法取得了较大的进步,但目前的测试精度(2 sd)约0.1‰,尚有提升的必要,还需开展更详细的实验工作。目前钙同位素的地质应用主要集中在地球表生低温过程,但高温地质过程中钙同位素的研究越来越引起研究者的兴趣。