北极海冰变化特征分析   总被引：3，自引：0，他引：3  

魏立新  张占海 《海洋预报》2007,24(4):42-48

本文利用NASA的海冰密集度资料(时间为1978年10月～2002年9月,分辨率为1.0×0.25),计算并分析了1978～2002年的北极海冰面积、范围的时间变化趋势以及变化的空间分布。  相似文献   

ENSO循环过程对南极海冰的影响   总被引：2，自引：0，他引：2       下载免费PDF全文

陈锦年  秦曾灏  褚健婷  许兰英 《极地研究》2003,15(2):129-137

应用 1 951- 2 0 0 2年NINO特征指数 (NINO1 +2 ,NINO3 ,NINO4 ,NINO3 .4)和 1 973-1 998年南极海冰北界范围以及 1 950- 2 0 0 1年SODA海洋温度资料。首先分析探讨了在ElNi no期间 ,堆积于赤道东太平洋的异常暖水在南半球的传播途径 ,进而研究了ENSO以及东南太平洋异常海温场与南极海冰之间的关系。结果表明 ,在ElNino期间 ,堆积于赤道东太平洋的异常暖水 ,是沿秘鲁和智利沿岸向极传播。其传播过程持续大约 1年的时间 ,但未发现沿南赤道流的西传现象。ENSO循环过程与南极海冰变化存在一定联系 ,特别是Amundsen Belling shausen海和南极半岛海冰的变化与ENSO暖事件 (ElNino)较为密切。当ElNino事件发生后 ,时滞 2年左右的时间 ,Amundsen Bellingshausen海和南极半岛的海冰将出现明显的减少现象 ,特别是南极半岛的海冰减少最为明显。ElNino事件对南极海冰的影响过程是 ,堆积于赤道东太平洋的大量异常暖水 ,沿南美 (秘鲁和智利 )沿岸近海向极地传播 ,异常暖水的这种向极传播过程将引起近极的海温场出现异常升高 ,最终导致Amundsen Bellingshausen海和南极半岛地区的海冰减少。自 2 0世纪 80年代以来 ,Amundsen Bellingshausen海和南极半岛的海冰出现明显减少的趋势 ,与这一时期的ElNino事件的频繁发生  相似文献   

从洛杉矶地区地震实验计划说起   总被引：3，自引：1，他引：3  

张先康 《国际地震动态》2003,(12):8-10

简要介绍了美国洛杉矶地震实验计划(LARSE)的研究目的、科学思路以及一些重要的研究成果。受LARSE计划实践的启发，文章对我国即将开展的城市活断层探测研究思路提出了几点科学认识：①进行深浅活动构造相结合的探测，建立直到震源深度的活动断裂立体图像；②实施折射／反射相结合的综合性探测，发展高分辨折射技术，弥补数百米-数千米深度范围成像的不足；③重要的活动断层常常具有一定的规模，在空间上构成复杂的构造格局，因此，活断层探测不能局限在城市，而应在一定的空间范围中进行。  相似文献   

Spatial Database of Geological Survey Extent in 20th Century in China     

WangQuanming YeTianzhu FangYiping ChenJianguo LiShuyu ZhangDaquan 《中国地质大学学报(英文版)》2003,14(3):220-226

During the whole 20th century in China, especially the latest 50 years, we have gotten much geological information about geological mapping, geophysics, geochemistry, mineral exploration,remote sensing, environmental geology, hydrogeology, engineering geology and oceanic geology etc. by our geologists and explorers. All the information has been accmnulated and can be used as a dcision-making foundation for the future plan of geological survey. The spatial database of geological survey ex-tents has been established by using computer technology. The database contained all kinds of exploration sections and collected about 160 000 records in this database. This paper introduces the data construc-tion ,contents and applying systemof this database, and trys to let people know what kinds of geological survey were finished, when the exploration were carried out, and how and where you can get this infor-mation.  相似文献   

Spatial Database Management System of China Geological Survey Extent   总被引：4，自引：0，他引：4  

ChenJianguo ChenZhijun WangQuanming FangYiping 《中国地质大学学报(英文版)》2003,14(3):250-256

The spatial database management system of China geological survey extent is a social service system. Its aim is to help the government and the whole social public to expediently use the spatial database, such as querying, indexing, mapping and product outputting. The management system has been developed based on MAPGIS6. x SDK and Visual C , considering the spatial database contents and structure and the requirements of users. This paper introduces the software structure, the data flow chart and some key techniques of software development.  相似文献   

Numerical and analytical observations on long and infinite slopes     

D. V. Griffiths  Jinsong Huang  Giorgia F. deWolfe 《国际地质力学数值与分析法杂志》2011,35(5):569-585

Interest in the mechanics of landslides has led to renewed evaluation of the infinite slope equations, and the need for a more general framework for estimating the factor of safety of long and infinite slopes involving non‐homogeneous soil profiles. The paper describes finite element methods that demonstrate the potential for predicting failure in long slope profiles where the critical mechanism is not necessarily at the base of the soil layer. The influence of slope angle is also examined in long slopes, leading to some counter‐intuitive conclusions about the impact of slope steepness on the factor of safety. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Drained cavity expansions in soils of finite radial extent subjected to two boundary conditions     

Mohammad Pournaghiazar  Adrian R. Russell  Nasser Khalili 《国际地质力学数值与分析法杂志》2013,37(4):331-352

The problem of drained cavity expansion in soils of finite radial extent is investigated. Cylindrical and spherical cavities expanded from zero radius subjected to either constant stress or zero displacement at the finite boundary are considered. The generalised analytical solution procedure presented enables more advanced constitutive models to be implemented than have been possible in previous studies. Results generated for Sydney quartz sand highlight substantial differences between cavity limit pressures for the two boundary conditions and for boundaries of finite and infinite radial extent. This is of significance in accounting for boundary effects when interpreting cone penetration tests conducted in calibration chambers. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

The System Analysis and Reliability Evaluation of Rock Slopes   总被引：1，自引：0，他引：1  

Luo Guoyu  Yan ChanghongDepartment of Earth Sciences  Nanjing University  Nanjing  Jiangsu Fei Zhenbi 《《地质学报》英文版》1994,68(4)

The principal of preferred plane analysis is a new research view and model of rock slope engineering geology. It advocates that the rock slope stability, boundary conditions and failure model are controlled by preferred planes. Therefore, the problem of slope stability evaluation can be converted into the search for preferred planes and determination of preferred separating bodies. The organic combination of the deterministic model and the indeterministic model can be realized by applying the systems engineering principle and the research model and method of reliability analysis in the quantitative evaluation and prediction of rock slope stability. Finally, the paper presents the case studies of slopes of the Yangtze Gorge Project and the Ma'anshan openpit mine.  相似文献   

Silent boundary for time domain wave motion analyses based on direct energy deletion     

M.O. Al-Hunaidi   《Soil Dynamics and Earthquake Engineering》1990,9(2)

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Absorbing boundary conditions for dynamic analysis of fluid-saturated porous media   总被引：8，自引：0，他引：8  

T. AkiyoshiK. FuchidaH. L. Fang 《Soil Dynamics and Earthquake Engineering》1994,13(6):387-397

Based on Biot's two-phase mixture theory and the paraxial approximation, the absorbing boundary conditions in the time domain for u-w, u-U and u-p formulations are presented for the dynamic analysis of fluid-saturated porous media. These absorbing boundaries are equivalent to the viscous boundaries in the fundamental mode. The expressions for the energy ratio and reflection coefficient between the reflected and incident waves along the absorbing boundary are given. The numerical results show that the proposed absorbing boundaries can greatly suppress the spuriously reflected wave and model the far field of the system. These results also dynamic analysis of infinite fluid-saturated porous media. for the transient dynamic analysis of infinite fluid-saturated porous media.  相似文献