苏门答腊地震的构造控制因素探讨

最近,在苏门答腊俯冲带展开了一系列相互关联的海上及陆地研究,重点针对印度尼西亚2004年和2005年的板块边界地震破裂。这项由英国(英国苏门答腊联盟)、印度尼西亚、美国、法国和德国的科学家联手开展的研究计划旨在对这一边缘的地壳结构进行成像,以分析沿走向和上倾方向地震破裂     

Experimental study of friction dissipators for seismic protection of building structures

This paper presents the results from unidirectional shaking table tests of two reduced scale steel models of a building frame, with one and two floors, respectively. These frames incorporate friction dissipators at every floor. The inputs are sine-dwells and artificial and registered earthquakes. This study is part of a larger research project aiming to assess the seismic efficiency of friction dissipators by means of an integrated numerical and experimental approach. Inside this framework, the main objectives of these experiments are to: (i) collect a wide range of results to calibrate a numerical model derived within the project, (ii) clarify some of the most controversial issues about friction dissipators (including behavior for inputs containing pulses, capacity to reduce resonance peaks, introduction of high frequencies in the response, and self-generated eccentricities), (iii) better understand their dynamic behavior, (iv) provide insight on the feasibility and reliability of using simple friction dissipators for seismic protection of building structures and (v) characterize the hysteretic behavior of these devices. Most of these objectives are satisfactorily reached and relevant conclusions are stated.     

用降雨和河川径流资料随机分析确定干旱事件的重现期

对建立的年系列而言,历时达一年的干旱事件重现期的计算可使用一些近似分布,然而对历时大于一年的水文事件的重现期,目前还没有现成的分析方法。本文的目的在于研究过去观测到的或将来可能发生的小降雨量和小河川径流量估算重现期的方法。在分析中使用了澳大利亚维多利亚五个主要水库入流和相应的流域平均降雨量资料。     

由哥伦比亚号航天飞机激发的地震

南加州的一些地震台记录了1989年8月13日哥伦比亚号航天飞机返回爱德华空军基地时引起的大气冲击波(图1)。除了这个冲击波外,在帕萨迪纳宽频IRIS-TERRA台站还记录了一个清晰的周期为2～3s的脉冲,它比冲击波早到12.5s(图2)。这个脉冲也被洛杉矶市区附近的南加州大学记录到,此处它比冲击波晚到3s。这个脉冲源不易马上识别出来。我们能够表明这     

A Theoretical Test of the Geostrophic Momentum Approximation

A previously developed model of a 2-dimensional air flow with constant horizontal shear is used to estimeate the accuracy of the geostrophic momentum approximation by comparison of exact solutions when exist with approximate ones.     

PRIMARY STUDY OF SULFATE AND CARBONACEOUS AEROSOLS IN BEIJING

Results of our aerosol study, performed during 1983–1984 in Beijing, demonstrate that ambient carbonaceous aerosols are derived mainly from coal combustion. Different SO₂ oxidation processes have been observed in summer and winter. The winter sulfate appears to be produced locally and associated with products of incomplete combustion.     

A NUMERICAL METHOD FOR SOLVING THE EVOLUTION EQUATION OF SOLITARY ROSSBY WAVES ON A WEAK SHEAR

In this paper an evoluion equation in integral-differential form for finite amplitude Rossby waves on a weak shear is presented and an efficient method for its numerical solution is set up. It is shown that a propagation of solitary wave is possible whenever a proper weak shear in basic flows acts with the nonlinear effects and dispersion of the media, both in the atmosphere and in the ocean. To test the numerical method for solving the evolution equation, a series of experiments are carried out. The results indicate that the solitary solutions, do exist and interact with each other in quite a succinct, manner. Therefore the method is successful and efficient for solving initial value problems of the above equation. The time decoupling problem arising in the numerical scheme and the related filtering technique are discussed. A variety of interesting phenomena such as the interaction of solitary Rossby waves, damping, dispersion and the development of nonlinear wave train are numerically studied.