Sequential integrated inversion of refraction and wide-angle reflection traveltimes and gravity data for two-dimensional velocity structures     

Rosaria Tondi  Roberto de Franco  & Riccardo Barzaghi' 《Geophysical Journal International》2000,141(3):679-698

A new algorithm is presented for the integrated 2-D inversion of seismic traveltime and gravity data. The algorithm adopts the 'maximum likelihood' regularization scheme. We construct a 'probability density function' which includes three kinds of information: information derived from gravity measurements; information derived from the seismic traveltime inversion procedure applied to the model; and information on the physical correlation among the density and the velocity parameters. We assume a linear relation between density and velocity, which can be node-dependent; that is, we can choose different relationships for different parts of the velocity–density grid. In addition, our procedure allows us to consider a covariance matrix related to the error propagation in linking density to velocity. We use seismic data to estimate starting velocity values and the position of boundary nodes. Subsequently, the sequential integrated inversion (SII) optimizes the layer velocities and densities for our models. The procedure is applicable, as an additional step, to any type of seismic tomographic inversion.
We illustrate the method by comparing the velocity models recovered from a standard seismic traveltime inversion with those retrieved using our algorithm. The inversion of synthetic data calculated for a 2-D isotropic, laterally inhomogeneous model shows the stability and accuracy of this procedure, demonstrates the improvements to the recovery of true velocity anomalies, and proves that this technique can efficiently overcome some of the limitations of both gravity and seismic traveltime inversions, when they are used independently.
An interpretation of field data from the 1994 Vesuvius test experiment is also presented. At depths down to 4.5 km, the model retrieved after a SII shows a more detailed structure than the model obtained from an interpretation of seismic traveltime only, and yields additional information for a further study of the area.  相似文献   

陆地中低放核废物地质处置的发展与现状   总被引：4，自引：0，他引：4  

刘平辉  管太阳  王勇 《华东地质学院学报》2000,23(3):229-234

介绍全球陆地中的中低放核废物处置的发展与现状,重点介绍近地表埋藏处置法,废矿井处置法和深岩硐地质处置法,并简要概述一些国家在陆地核废物处置领域内出现的问题及对策。  相似文献   

长沙电力学院3号教学楼人工挖孔灌注桩工程地质问题及其处理措施     

杨建成  明邵军 《湖南地质》2000,19(2):121-124

长沙电力学院 3号教学楼人工挖孔桩基的施工条件极差。经灵活采用多种经济实用的措施处理 ,成功地解决了流砂、流泥、管涌、坍塌、护壁吊烂与整体失稳等技术难题。  相似文献   

Problem regions and regional problems of socioeconomic development in China: A perspective from the coordinated development of industrialization,informatization, urbanization and agricultural modernization     

Yurui Li  Jing Wang  Yansui Liu  Hualou Long 《地理学报(英文版)》2014,24(6):1115-1130

Identifying the problem regions and regional problems, and thus improving regional policies, are crucial for the sustainable development of various economic entities. The coordinated development of industrialization, informatization, urbanization and agricultural modernization（hereinafter referred to as ＂Sihua＂） is not only a practical need but an important strategic direction of integrating urban-rural development and regional development in recent China, and it also provides a significant perspective for identifying problem regions and regional problems so as to improve the regional policies. This study mainly aims to： firstly, establish a comprehensive evaluation index system so as to explore the spatial pattern of coordinated development of Sihua in China at prefecture level; secondly, to develop an evaluation criteria system to identify the problem regions and regional problems from the perspective of coordinated development of Sihua. This paper comes first in the scientific community to evaluate the coordinated development state of Sihua in China at prefecture level and identify the problem regions and regional problems from the perspective of Sihua development by quantitative analysis. This study may benefit the improvement of regional policies and thus contribute to the sustainable socio-economic development of China.  相似文献   

A new modelling method for evaluating external disturbing potential based on theory of unified representation of gravitational field     

ZHU Zhuowen HUANG Jinshui CAO Huasheng LUO Zhicai 《地球空间信息科学学报》2000,3(2):41-46

1　ＩｎｔｒｏｄｕｃｔｉｏｎＣｏｎｖｅｎｔｉｏｎａｌｅｖａｌｕａｔｉｎｇｍｏｄｅｌｓｏｆｅｘｔｅｒｎａｌｇｒａｖｉ ｔａｔｉｏｎａｌｆｉｅｌｄｏｆｔｈｅｅａｒｔｈａｒｅｎｏｔｈｉｎｇｅｌｓｅｔｈａｎａｋｉｎｄｏｆｒｅａｌｉｚａｔｉｏｎｓｏｆｎｕｍｅｒｉｃａｌｓｏｌｕｔｉｏｎｓｔｏｇｅｏｄｅ ｔｉｃｂｏｕｎｄａｒｙｖａｌｕｅ ｐｒｏｂｌｅｍ .Ｉｎｔｈｅｓｅｎｓｅｏｆｌｉｎ ｅａｒｉｚａｔｉｏｎ ,ｇｅｏｄｅｔｉｃｂｏｕｎｄａｒｙｖａｌｕｅｐｒｏｂｌｅｍｓａｒｅｒｅ ｄｕｃｅｄｔｏｅｘｔｅｒｎａｌｂｏｕｎｄ…  相似文献   

浅析宜昌磷矿开发中存在的问题及对策   总被引：5，自引：0，他引：5  

李锦文 《化工矿产地质》2000,22(3):183-187

宜昌磷矿资源量大、品位高。经过 30余年的发展 ,已成为该地区经济收入的重要来源之一。但在开发中仍存在矿山规模过小过滥 ,设备利用率低 ,建设资金浪费 ,采富弃贫 ,资源严重浪费 ;产品附加值低 ,可持续发展后劲泛力 ;矿业秩序混乱 ,安全陷患多 ;生态环境严重被破坏等问题。针对存在问题应采取的对策为缩小开采规模 ,提高产品附加值 ;减少矿山生活服务设施投入 ,增加矿山企业的生产规模 ;减少村办、个体小矿山 ,坚持国有矿山的主导地位以及加强区域间合作 ,走矿肥集合与矿化集合的道路等。  相似文献   

A least-squares penalty method algorithm for inverse problems of steady-state aquifer models     

Hailong Li  Qichang Yang 《Advances in water resources》2000,23(8)

Based on the generalized Gauss–Newton method, a new algorithm to minimize the objective function of the penalty method in (Bentley LR. Adv Wat Res 1993;14:137–48) for inverse problems of steady-state aquifer models is proposed. Through detailed analysis of the “built-in” but irregular weighting effects of the coefficient matrix on the residuals on the discrete governing equations, a so-called scaling matrix is introduced to improve the great irregular weighting effects of these residuals adaptively in every Gauss–Newton iteration. Numerical results demonstrate that if the scaling matrix equals the identity matrix (i.e., the irregular weighting effects of the coefficient matrix are not balanced), our algorithm does not perform well, e.g., the computation cost is higher than that of the traditional method, and what is worse is the calculations fail to converge for some initial values of the unknown parameters. This poor situation takes a favourable turn dramatically if the scaling matrix is slightly improved and a simple preconditioning technique is adopted: For naturally chosen simple diagonal forms of the scaling matrix and the preconditioner, the method performs well and gives accurate results with low computational cost just like the traditional methods, and improvements are obtained on: (1) widening the range of the initial values of the unknown parameters within which the minimizing iterations can converge, (2) reducing the computational cost in every Gauss–Newton iteration, (3) improving the irregular weighting effects of the coefficient matrix of the discrete governing equations. Consequently, the example inverse problem in Bentley (loc. cit.) is solved with the same accuracy, less computational effort and without the regularization term containing prior information on the unknown parameters. Moreover, numerical example shows that this method can solve the inverse problem of the quasilinear Boussinesq equation almost as fast as the linear one.In every Gauss–Newton iteration of our algorithm, one needs to solve a linear least-squares system about the corrections of both the parameters and the groundwater heads on all the discrete nodes only once. In comparison, every Gauss–Newton iteration of the traditional method has to solve the discrete governing equations as many times as one plus the number of unknown parameters or head observation wells (Yeh WW-G. Wat Resour Res 1986;22:95–108).All these facts demonstrate the potential of the algorithm to solve inverse problems of more complicated non-linear aquifer models naturally and quickly on the basis of finding suitable forms of the scaling matrix and the preconditioner.  相似文献   

初论农业环境地质与农业环境地质问题   总被引：3，自引：0，他引：3  

严宝文  李靖 《水文地质工程地质》2000,27(5):41-43

本文初步提出了农业环境地质的概念,对它的科学地位和学科体系进行了探讨,并简述了五类主要的农业环境地质问题,以期丰富环境地学学科内容,保进农业环境地质研究。  相似文献   

上海地下工程的技术问题     

倪德祥  陈孝培 《上海国土资源》2000,(1):37-41

进入９０年代以来,上海的建（构）筑物迅速向高、大、深、重的方向发展,从而使地下工程的试验、研究、设计、施工和监测,成为上海岩土工程界的主攻方向。在软土地基上进行桩基旋工、开挖深基坑和沉井工程,都会对软弱土体产生扰动和破坏,推动稳定性的土体所表现的应用应变复杂过程,随时都会给工程带来危害。上海岩土工程界从众多工程事故实例中取得经验教训,摸索到一套行之有效的办法,对于常见的上海地下工程技术问题,从原理  相似文献   

强震短期前兆异常特征物理分析和解释的研究进展   总被引：6，自引：0，他引：6  

刘耀炜  牛安福  卢军 《地震》2004,24(4):57-65

总结了“十五” 国家科技攻关项目强震短期前兆异常特征的物理分析和解释方面的研究成果, 并将主要进展归纳为4个方面, 即: 通过大量台网数据的扫描处理和震例研究, 分析了地电、 地形变、 地下流体强震短期前兆的典型特征; 提出了典型短期前兆特征依托的实验基础和理论依据, 进行了数值模拟和理论解释; 通过数值模拟方法, 探讨了短期地震活动性图像特征和强余震触发机理; 总结了大陆强地震的卫星热红外异常演化过程, 提出了活动断裂带内、 外温度和地表温度场提取的技术方法。  相似文献