用四维反演方法研究地震活动的深部环境   总被引：1，自引：0，他引：1       下载免费PDF全文

刘天铭  苏瑞  张伯宏 《地震工程学报》2001,23(3):217-223,237

导出了用重力和水准重复测量资料反演地壳界面密度和垂直形变随时间变化的四维反演公式，并对甘肃河西地区（包括祁连山地区）和滇西北地区的重力和水准重复测量资料进行了计算。根据计算结果，分析了2个地区莫霍西密度变化速率和垂直形变速率与地震的关系。结果表明：甘肃河西地区和滇西北地区莫霍面密度大规模减小和莫霍面大范围隆起可作为1年尺度的地震预报的深部判据。地震往往发生在莫霍面隆起区与沉降区、密度减小区与增长区的过渡地带。  相似文献   

从地壳运动角度分析大陆强震机理的一种物理方法   总被引：4，自引：0，他引：4  

申重阳  吴云  甘家思 《中国地震》2001,17(1):70-81

为了从地壳运动角度利用重复大地测量数据分析大陆强震机理,提出了利用反映地壳内部密度变化或时变的物理量来分析强震发生的密度变化机理的一种物理方法(1)介绍了地球内部密度时变的一般理论和单层密度时变理论,提出了分步迭代算法;(2)简要分析了断层位错引起的单层密度变化效应;(3)分析了1996年丽江7级地震前震区南部地壳密度时变(变化)的特征;(4)初步探讨了强震孕育过程中可能的地壳内部密度时变(变化)前兆模式或发震机制.  相似文献   

遥感技术在鄂尔多斯盆地东南部煤层气勘探中的应用   总被引：1，自引：0，他引：1  

余华琪  齐小平 《国土资源遥感》2001,12(3):11-14,69

从鄂尔多斯盆地黄土塬区煤层气勘探的实际需要出发,通过遥感解译,利用裂缝密度统计分析方法,对研究区煤层气高渗区带进行了预测,并对区内煤层气勘探的有利区带进行了初步评价,为煤层气勘探提供了重要的参考资料.  相似文献   

超声波测定盐湖卤水的密度          下载免费PDF全文

王庆忠  祁永唐  李青凤 《盐湖研究》2001,9(3):27-31

叙述了超声波在与盐湖卤水组成相关的 Mg Cl2 溶液、Na Cl溶液、Mg Cl2 和 Na Cl的混合溶液中的声时与溶液浓度、溶液温度等之间的关系 ,测定了察尔汗不同蒸发阶段的盐湖卤水密度、声时和温度值 ,并针对察尔汗盐湖卤水组成 ,将获得的实验值采用拟合及插值的方法编制成计算机程序储存在单片机中 ,从而实现了察尔汗盐湖卤水蒸发过程中密度的自动监测  相似文献   

Homotopy scattering series for seismic forward modelling with variable density and velocity     

Kui Xiang  Kjersti Solberg Eikrem  Morten Jakobsen  Geir Nvdal 《Geophysical Prospecting》2022,70(1):3-18

We have derived a convergent scattering series solution for the frequency-domain wave equation in acoustic media with variable density and velocity. The convergent scattering series solution is based on the homotopy analysis of a vectorial integral equation of the Lippmann–Schwinger type. By using the Green's function and partial integration, we have derived the vectorial integral equation of the Lippmann–Schwinger type that involves the pressure gradient field as well as the pressure field from the wave equation. The vectorial Lippmann–Schwinger equation can in principle be solved via matrix inversion, but the computational cost of matrix inversion scales like $N^3$, where $N$ is the number of grid blocks. The computational cost can be significantly reduced if one solves the vectorial Lippmann–Schwinger equation iteratively. A simple iterative solution is the Born series, but it is only convergent when the scattering potential is sufficiently small. In this study, we have used the so-called homotopy analysis method to derive an iterative solution for the vectorial Lippmann–Schwinger equation which can be made convergent even in strongly scattering media. The computational cost of our convergent scattering series scales as $N^2$. Our algorithm, which is based on the homotopy analysis method, involves a convergence control operator that we select using hierarchical matrices. We use a three-layer model and a resampled version of the SEG/EAGE salt model to show the performance of the developed convergent scattering series.  相似文献   

Determining the road traffic accident hotspots using GIS-based temporal-spatial statistical analytic techniques in Hanoi,Vietnam     

Khanh Giang Le  Pei Liu  Liang-Tay Lin 《地球空间信息科学学报》2020,23(2):153-164

ABSTRACT

This study applied GIS-based statistical analytic techniques to investigate the influence of accident Severity Index (SI) on temporal-spatial patterns of accident hotspots related to the specific time intervals of day and seasons. Road Traffic Accident (RTA) data in 3 years (2015 ? 2017) in Hanoi, Vietnam were used to analyze and test this approach. Firstly, the RTA data were divided into four seasons in accordance with Hanoi’s weather conditions and the time intervals such as the daytime, nighttime, or peak hours. Then, the Kernel Density Estimation (KDE) method was applied to analyze hotspots according to the time intervals and seasons. Finally, the results were presented by using the comap technique. This study considered both analyses with and without SI. The accident SI measures the seriousness of an accident. The approach method is to give higher weights to the more serious accidents, but not with the extremely high values calculated on a direct rate to the accident expenditures. The results showed that both analyses determined the relatively similar hotspots, but the rankings of some hotspots were quite different due to the integration of SI. It is better to take into account SI in determining RTA hotspots because the gained results are more precise and the rankings of hotspots are more accurate. From there, the traffic authorities can easily understand the causes behind each accident and provide reasonable solutions to solve the most dangerous hotspots in case of limited budget and resources appropriately. This is also the first study about this issue in Vietnam, so the contribution of the article will help the traffic authorities easily solve this problem not only in Hanoi but also in other cities.  相似文献   

X线CT机选型的依据     

丁文奎  张国桢 《CT理论与应用研究》1993,(1)

本文描述了X 线CT 机的几个主要技术特性,并根据这些特性,计论如何去选择一台价格低、图像质量高的CT 扫描机。  相似文献   

地震-重力联合反演中的非块状一致性模型   总被引：6，自引：3，他引：6  

冯锐  陶裕录 《地球物理学报》1993,36(4):463-475

完善地震-重力联合反演的一个重要措施是建立一致性模型.本文按照地震测深的常用办法,采用二维四边形非块状模型,通过网格节点的密度值来刻划连续性或间断性的物性分布.四边形单元内部的密度分布为双线性函数,本文给出了重力异常的严谨解析式.计算中可采用模型分解技术,将四边形化为矩形与直角三角形的组合,简化程序设计.算法的实施有两种途径:独立单元法和整体模型法.在联合反演的数值模拟中,还推出了剪切模量μ模型以及纵波速度V_P,与密度ρ的分布关系.  相似文献   

黑水─泉州地学断面的重磁解释          下载免费PDF全文

王懋基 《地球物理学报》1994,(3)

讨论华南黑水─泉州地学断面的重磁解释。在解释中除应用常规的２．５维重磁异常反演外，还采用等密度线算法构制梯度层密度模型，用于分辨地壳密度细结构，以及计算自由地幔而深度用于分析上地幔密度的横向不均匀性。重磁模拟结果揭示了１０ｋｍ深度内的上地壳构造以及地壳与上地幔密度的分布。提出华南造山带以低密度上地幔为特征，它可能与上地幔的改造有关；四川盆地具有较高的上地幔密度，为未经改造的原始地幔。扬子克拉通与华南造山带的分界线与上地幔密度的分界线一致。根据布格异常、地表岩石密度和地形资料的综合分析，圈定出反映内生成矿作用深部标志的密度倒转区，可作为进一步找矿的远景区。  相似文献   

前苏联铁路网的形成、发展和布局     

冯春萍 《世界地理研究》1994,(2)

前苏联是世界上铁路运输利用率最高的国家。本文从其铁路发展的背景条件出发，分析了铁路成为前苏联最主要运输方式的原因，并进一步探讨了前苏联铁路网的建设、发展和分布特点，对我国正在进行的大规模铁路建设有一定借鉴意义。  相似文献