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951.
LONG Si-sheng 《地震学报(英文版)》2000,13(5):491-498
Twenty-two earthquakes (M
L=2.2–3.7) in the joint region of Xianshuihe, Longmenshan and An’ninghe faults are studied in this paper. The source mechanism
solutions of these events are obtained using P-wave first motion method, and the characteristics of the source stress field
and rupture in the joint region are summarized preliminarily with some results of other researchers. Being strongly extruded
by the approximately horizontal regional stress with the direction from north-west to south-east and the effect of the complex
tectonics in the region, the source stress field has complex and variable characteristics. The earthquakes mainly show normal
or strike-slip faults in Yajiang, North-triangle and west of Chengdu-block areas, indicating that the vertical forces have
been playing an important role in the source stress fields, while the earthquakes mainly show reverse or strike-slip faults
in Baoxing-Tianquan area, with the horizontal components of the principal pressure stress axes identical to the south-west
direction to which the shallow mass is moving. We think that the manifold combinations of earthquake faults are the micro-mechanism
based upon which the large regional shallow crust mass has been moving continually. 相似文献
952.
IntroductionSichuan region is one of the extruded and connected parts between the Qinghai-Xizang (Tibet) Plateau and Yangtze block. And the joint region of Xianshuihe, Longmenshan and An(ninghe faults reflects the structure characteristics formed by the Qinghai-Xizang Plateau(s extruding to Yangtze block and the Sichuan basin evolutionary process as fore-land basin. The researches on seismic activity in Sichuan region were mainly around Xianshuihe, Longmenshan and An(ninghe faults separ… 相似文献
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956.
Optimal Design of TMD Under Long-Term Nonstationary Wave Loading 总被引:3,自引:0,他引:3
—Traditionally,the use of a tuned mass damper(TMD)is to improve the surviability of the pri-mary structure under extraordinary loading environment while the design loading condition is describedby either a harmonic function or a stationary random process that can be fully characterized by a powerspectral density(PSD)function.Aiming at prolonging the fatigue life of an offshore platform,this studyconsiders an optimal design of TMD for the platform under long-term nonstationary loading due tolong-term random sea waves characterized by a probabilistic power spectral density(PPSD)function.Inprinciple,a PPSD could be derived based on numerous ordinary PSD functions;and each of them is treat-ed as realization of the corresponding PPSD.This study provides a theoretical development for theoptimal TMD design by minimizing the cost function to be the mean square value of the expectedlong-term response.A numerical example is presented to illustrate the developed design procedure. 相似文献
957.
利用综合孔径射电望远镜在 232 MHz观测太阳,具有 3·8’的空间分辨率、 20 ms 的时间分辨率和高灵敏度及很好的抗干扰能力.1999年共观测到12次大爆发,其中8次与日冕物质抛射相关.可以利用米波射电爆发预报CME事件. 相似文献
958.
CHASCA TWYMAN 《The Geographical journal》2000,166(4):323-335
This paper examines the complexities of participatory conservation through a case study of the process of participation in a government funded community-based natural resource management programme in Western Botswana. The paper argues that different stakeholders have very different views on the levels of participation taking place in particular projects. Furthermore local people find it difficult to voice their concerns about the environment and issues of sustainability given the power relations involved in this 'participatory'process. The paper questions the accountability and motivation of the different stakeholders involved in participatory projects and suggests that implicit in the policy implementation process are mechanisms which constrain empowerment and dictate the forms of participatory conservation which can emerge. The paper concludes by reviewing the case study in the light of new policy developments in Botswana. 相似文献
959.
DAVID SMETHURST 《Geographical review》2000,90(1):35-56
ABSTRACT. Although mountains have been studied for centuries, they are the subject of only a slender body of formal literature. Instead, those who study high places in specific regions construct working definitions and continually recraft bibliographies. Studies of mountains often focus on comparatively limited themes: physical processes, ecology, or sacred spaces, for example. As scholars become interested in environmental degradation and the development of mountains, there is all the more need to develop a mountain geography literature that expands the study of mountains to include the political, economic, cultural, and social dimensions of their environments and peoples. Three areas‐cultural geography, political ecology, and conservation theory‐are suggested for additional research. 相似文献
960.
利用几种不同的半经验公式计算一批OH/IR星的质量损失率,并通过比较计算结果来讨论所用的公式.在一些情况下,计算质量损失率必须先给定气尘比.通过计算出样品星的气尘比,并讨论气尘比的变化情况,以修正由尘埃质量损失率到总质量损失率的关系式. 相似文献