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排序方式: 共有6210条查询结果,搜索用时 15 毫秒
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Determination of gravity anomaly at sea level from inversion of satellite gravity gradiometric data 总被引:1,自引:0,他引:1
Gravity gradients can be used to determine the local gravity field of the Earth. This paper investigates downward continuation of all elements of the disturbing gravitational tensor at satellite level using the second-order partial derivatives of the extended Stokes formula in the local-north oriented frame to determine the gravity anomaly at sea level. It considers the inversion of each gradient separately as well as their joint inversion. Numerical studies show that the gradients Tzz, Txx, Tyy and Txz have similar capability of being continued downward to sea level in the presence of white noise, while the gradient Tyz is considerably worse than the others. The bias-corrected joint inversion process shows the possibility of recovering the gravity anomaly with 1 mGal accuracy. Variance component estimation is also tested to update the observation weights in the joint inversion. 相似文献
84.
M. Erdik K. ŞeşetyanM.B. Demircioğlu U. HancılarC. Zülfikar 《Soil Dynamics and Earthquake Engineering》2011
This article summarizes the work done over the last decades regarding the development of new approaches and setting up of new applications for earthquake rapid response systems that function to estimate earthquake losses in quasi-real time after an earthquake. After a critical discussion of relevant earthquake loss estimation methodologies, the essential features and characteristics of the available loss estimation software are summarized. Currently operating near-real-time loss estimation tools can be classified under two main categories depending on the size of area they cover: global and local systems. For the global or regional near-real-time loss estimation systems: GDACS, WAPMERR, PAGER, and NERIES-ELER methodologies are presented together with their loss estimations for the 2009 Abruzzo (L’Aquila) earthquake in Italy. Examples are provided for the local rapid earthquake loss estimation systems, including the Taiwan Earthquake Rapid Reporting System, Real-time Earthquake Assessment Disaster System in Yokohama, Real Time Earthquake Disaster Mitigation System of the Tokyo Gas Co., and Istanbul Earthquake Rapid Response System. 相似文献
85.
The Tianjin coastal area is a typical soft soil region,where the soil is a marine deposit of the late Quaternary.The soil dynamic parameters from seismic risk assessment reports are collected,and drilling of 15 holes was carried out to sample the soils and measure their dynamic characteristics.The data was divided into 7 types based on lithology,namely,muddy clay,muddy silty clay,silt,silty clay,clay,silty sand and fine sand.Statistics of the dynamic parameters of these soils are collected to obtain the mea... 相似文献
86.
We develop a new Proper Orthogonal Decomposition (POD) reduced order model for saturated groundwater flow, and apply that model to an inverse problem for the hydraulic conductivity field. We use sensitivities as the POD basis. We compare the output when the optimizer uses the reduced order model against results obtained with a full PDE based model. The solutions generated using the POD reduced model are comparable in residual norm to the solutions formed using only the full-scale model. The material parameters are similarly comparable. The time to solution when using the reduced model is reduced by at least an order of magnitude, as are the number of calls to the full model. 相似文献
87.
Sarah E. Gasda 《Advances in water resources》2011,34(10):1268-1282
Split-operator methods are commonly used to approximate environmental models. These methods facilitate the tailoring of different approximation approaches to different portions of the differential operator and provide a means to split large coupled problems into pieces that are more amenable to parallel computation than the original fully-coupled problem. However, split-operator methods introduce an additional source of approximation error into the solution, which is typically either ignored or controlled heuristically. In this work, we develop two methods to estimate and control the error in split-operator methods, which lead to a dynamic adjustment of the temporal splitting step based upon the error estimators. The proposed methods are shown to yield robust solutions that provide the desired control of error. In addition, for a typical nonlinear reaction problem, the new methods are shown to reduce the solution error by more than two orders of magnitude compared to standard methods for an identical level of computational effort. The algorithms introduced and evaluated have widespread applicability in environmental modeling. 相似文献
88.
基于区域构造背景、应力场状态及动力学环境等,将青藏高原北部地区划分为4个相对独立的统计单元,即祁连山地震带、甘东南地区、柴达木一共和地块及库玛地震带.通过地震频度和b值拟合确定了各个地区不同下限震级的地震目录完整性起始时间;确定了各构造单元中强以上地震活跃与平静交替活动的特征;定量计算了在平均状态中强以上地震活动特征参数及平静阶段与活跃阶段地震活动特征参数;分别获得了各个区域在平均、活跃与平静状态下的小震活动状态参数. 相似文献
89.
90.
大连地区场地土动力学参数初步研究 总被引:1,自引:0,他引:1
通过收集近年来大连地区地震安全性评价报告中土动力学参数的实验资料,统计分析粉质粘土、淤泥质粉质粘土、粘土、中砂、碎石、回填土和全风化板岩等7类土的实测动力学参数,给出了它们的动剪切模量比和阻尼比的统计值.然后,选取典型钻孔并建立了土层地震反应分析模型,分别运用本文统计值、94规范值(即原大连地震小区划的土动力学参数值)和袁晓铭等(2000)的推荐值进行土层地震反应计算,并将计算结果中的地表峰值加速度和反应谱形状进行了比较.结果表明,本文的统计值与袁晓铭等( 2000)的推荐值非常接近,而与94规范值有很大的差别. 相似文献