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151.
昂仁组是一套复理石和类复理石沉积,含晚白垩世土伦期的菊石Mammites[1,2],但因未发现直接的上覆地层和化石稀少而不能肯定是否还包括晚于土伦期或至早第三纪的沉积[1,3]。1980年,笔者在昂仁、萨噶一带的昂仁组中采到瓣鳃、腹足化石;我局区调队在仲巴县错江顶一带,发现连续沉积于昂仁组之上,整合于下第三系之下一套含Masstrichtian期菊石(Sphenodiscus)的杂色地层。本文报道这一发现和对昂仁组时代问题的认识(图1)。 相似文献
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153.
In this paper, we present a new approach to estimate high-resolution teleseismic receiver functions using a simultaneous iterative time-domain sparse deconvolution. This technique improves the deconvolution by using reweighting strategies based on a Cauchy criterion. The resulting sparse receiver functions enhance the primary converted phases and its multiples. To test its functionality and reliability, we applied this approach to synthetic experiments and to seismic data recorded at station ABU, in Japan. Our results show Ps conversions at approximately 4.0 s after the primary P onset, which are consistent with other seismological studies in this area. We demonstrate that the sparse deconvolution is a simple, efficient technique in computing receiver functions with significantly greater resolution than conventional approaches. 相似文献
154.
Dev Niyogi Hsin-I Chang Fei Chen Lianhong Gu Anil Kumar Surabi Menon Roger A. Pielke Sr. 《Natural Hazards》2007,42(2):345-359
Aerosols can affect the cloud-radiation feedback and the precipitation over the Indian monsoon region. In this paper, we propose
that another pathway by which aerosols can modulate the multi-scale aspect of Indian monsoons is by altering the land–atmosphere
interactions. The nonlinear feedbacks due to aerosol/diffuse radiation on coupled interactions over the Indian monsoon region
are studied by: (1) reviewing recent field measurements and modeling studies, (2) analyzing the MODIS and AERONET aerosol
optical depth datasets, and (3) diagnosing the results from sensitivity experiments using a mesoscale modeling system. The
results of this study suggest that the large magnitude of aerosol loading and its impact on land–atmosphere interactions can
significantly influence the mesoscale monsoonal characteristics in the Indo-Ganges Basin. 相似文献
155.
A simplified approach for vulnerability assessment in moderate-to-low seismic hazard regions: application to Grenoble (France) 总被引:3,自引:2,他引:3
Philippe Guéguen Clotaire Michel Laele LeCorre 《Bulletin of Earthquake Engineering》2007,5(3):467-490
Due to the moderate seismic risks in France, the building vulnerability assessment methods developed for high seismic risk
countries could not easily be used here because of their cost and the low-risk perception among the public and officials.
A light vulnerability assessment method is proposed and tested in Grenoble (France), based on classes and scores provided
in the GNDT method but simplified in terms of visual screening and number of structural parameters used. Compared to the RiskUE
method, the damage obtained by our approach shows that 90% of buildings have residuals smaller than 0.2, i.e. one grade of
the EMS98 damage scale. A large scale survey is devised and conducted among the inhabitants of Grenoble in order to collect
the main structural parameters. By comparing the results from the survey to the historical urbanization of Grenoble and to
expert surveys performed in two urban districts, the information useful for the light method of vulnerability assessment can
be rapidly collected by non-experts reducing substantially the estimate cost. The average damage is then computed using the
GNDT formula considering the probable intensities which could be observed in Grenoble (VII and VIII). The average damage reaches
0.4 in the oldest part of Grenoble mainly made of masonry buildings and 0.2 in reinforced concrete suburbs where reinforced
concrete predominates. The results are a relative vulnerability assessment that provides useful initial information for the
urban zones of Grenoble where the vulnerability is higher. This method can be used to classify the seismic vulnerability in
wide seismic-prone regions to a fair degree of accuracy and at low cost. 相似文献
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157.
本文应用卫星云图与数值模拟结果对2000年6月2日发生的一次影响江苏的江淮气旋暴雨过程进行研究分析,阐述了这次暴雨过程表现的MCS基本特征。分析表明:MCS的形成可以由几个中β尺度对流云或对流带开始,在特定的环境场中汇合成合并;在其发展过程中必须维持湿度平流,低层到中层有暖平流,骨强偏南风急流伸向形成区,同时在其东北方向有一支高空西风急流相耦合;低层的辐合、整层凝结潜热的释放、垂直运动的增强、高层的辐散引起的正反馈机制是MCS发展的动因。 相似文献
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