地球物理反问题中的随机反演理论     

周竹生  陆江南 《物探化探计算技术》1997,19(4):289-297

本文从最大后验概率密度观点出发，在数据噪音向量和待求模型向量为具有零均值的独立高斯随机过程的假设前提下，建立起了随机反演的非线性系统方程；给出了模型方差估计的函数表达式，并在文章最后，证明了反演解的稀疏性，即解释了随机反演的输出解的高分辨率特征。文章在最小二乘反演方法的基础上，发展并完善了随机反演方法的理论基础；揭示了随机反演方法与最小二乘反演方法之间的本质区别；阐述了随机反演方法的优越性，并指出了其广阔的应用前景。  相似文献   

A bivariate meta-Gaussian density for use in hydrology   总被引：3，自引：0，他引：3  

K. S. Kelly  R. Krzysztofowicz 《Stochastic Environmental Research and Risk Assessment (SERRA)》1997,11(1):17-31

Convenient bivariate densities found in the literature are often unsuitable for modeling hydrologic variates. They either constrain the range of association between variates, or fix the form of the marginal distributions. The bivariate meta-Gaussian density is constructed by embedding the normal quantile transform of each variate into the Gaussian law. The density can represent a full range of association between variates and admits arbitrarily specified marginal distributions. Modeling and estimation can be decomposed into i) independent analyses of the marginal distributions, and ii) investigation of the dependence structure. Both statistical and judgmental estimation procedures are possible. Some comparisons to recent applications of bivariate densities in the hydrologic literature motivate and illustrate the model.  相似文献   

Methodical approach to distribution of epilithic and drifting algae communities in a French subalpine river: Inferences on water quality assessment   总被引：2，自引：0，他引：2  

Thierry Rolland  Stéphanie Fayolle  Arlette Cazaubon  Stéphane Pagnetti 《Aquatic Sciences - Research Across Boundaries》1997,59(1):57-73

In a sub-alpine river, the Asse, with an unpredictable discharge regime, chlorophyll, density and taxonomic diversity of both drifting and periphytic communities were studied from a methodical approach. The investigations based on stamping two close cross-sections to know their spatial distributions in a heterogeneous bed substrate showed a heterogeneous pattern of colonization mainly influenced by hydrological variables as the current velocity, the size of the substrata (gravel-pebble-boulder). For the drifting algae, mainly composed with benthic species temporarily unhooked to the substrata, the heterogeneity of the distribution was reduced in fast flow which induced a mixing of the whole mass of water. For the periphyton, some results indicated that the greatest diversity and the highest chlorophyll concentration were found on pebble substratum where the current velocity was moderate. These results have also shown that the classical methods used to day for investigations were inadequate for most Mediterranean rivers. It was really difficult to estimate the water quality from classical index created for use in regular large plain rivers.  相似文献   

The law of dislocation between two sides of active faults in China and their geodynamic force     

Shuangzhong Yu  Xungang Shi  Wenping Li 《中国科学D辑(英文版)》1997,40(6):613-620

By contrasting and analyzing the characteristics of gravity field nearby some important active faults in the continent of China, it can be found that the crust blocks where Bouguer anomalies are regionally positive (or relatively positive) are moving towards the terrestrial poles and the blocks where Bouguer anomalies in a tremendous area are negative (or relatively negative) are moving towards the equator. By analysis of mechanics and mathematics calculation and based on lots of practical data, the authors hold that the change in density of a crust block is a decisive factor that causes the horizontal movement of the continental crust, while magma activity is an important factor that leads to the change in density of a crust block.  相似文献   

Assessment of hydrogeological conditions in basement aquifers of the Precambrian Oban massif, southeastern Nigeria   总被引：1，自引：0，他引：1  

A.E. Edet  C.S. Okereke 《Journal of Applied Geophysics》1997,36(4):195-204

A combined analysis of lineament length density from radar imagery and surface resistivity data is used to assess the hydrogeological conditions in the Oban massif, Nigeria. The results show that the data guided the qualitative and quantitative estimation of some aquifer parameters. These include resistivity of the water bearing formations (280–740 ω m), thickness (5–140 m), limited hydraulic conductivity (8.53-13.18 m/day) and transmissivity (410.65–725.88 m²/day) data. In addition, the lineament length density for the area ranged between less than 0.2 to slightly more than 0.4. Site evaluation for the location of productive boreholes/wells using a groundwater potential index (GWPI) indicates that areas with a GWPI of greater than 35 are consistent with relatively high yield.  相似文献   

参数椭球表面的重力   总被引：10，自引：0，他引：10       下载免费PDF全文

郝晓光 《地球科学》1997,22(2):223-226

推导了带密度参数的界面深度参数的旋转椭球表面重力的封闭公式，提出了“参数椭球”的概念。  相似文献   

PDC钻头切削齿受力随布齿密度变化关系研究   总被引：1，自引：0，他引：1  

罗超  王镇泉 《地质与勘探》1997,33(4):60-63

采用不同布齿方式的３个ＰＤＣ切削齿同步连续切削转动的岩石为模拟井底钻头切削齿实际工作状态，用切削岩石时相同的布齿参数切削砂轮来磨损切削以模拟切削的以模拟切削齿磨状态，试验研究了不同磨损程度的切削齿受力与布齿密度的关系。  相似文献   

高密度电阻率法在地下涵洞勘测中的应用   总被引：1，自引：2，他引：1  

汤洪志  官云鹏 《华东地质学院学报》1997,20(4):343-348

本文介绍的高密度电阻率法是一种新兴的电阻率方法，与常规电阻率方法相比，高密度电阻率法具有成本低，效率高，测点密集，反映地电信息更丰富，更直观以及资料解释简单方便等特点。本文运用高密度电阻率法勘测地下涵洞，实践证明，高密度电阻率法获得的图形，质量高，解释误差小，是一种方便实用，效果良好，能广泛应用于工程勘测的物探方法。  相似文献   

城市地震影响特征研究   总被引：6，自引：2，他引：6       下载免费PDF全文

潘华  赵凤新  高孟潭 《地震学报》2004,26(2):203-210

首先根据历史地震目录，计算了我国34个省会城市所受到的历史地震影响. 这些城市的地震影响烈度分布特征表明，约53%的省会城市没有遭受过Ⅵ度以上的历史地震影响，遭受过Ⅶ~Ⅸ度影响的城市有44%；大部分城市Ⅵ度地震影响的发生频次均高于Ⅵ度以上地震影响；不同城市最大发生频次的地震影响烈度也不同. 为此，在确定城市地震防御烈度时，需综合考虑最大影响烈度和最频影响烈度. 本文还考虑到历史地震记录的不完备性，以福建省69个县级以上城市为研究对象，采用模拟地震目录的方法来研究城市地震影响的特征. 结果表明，不同超越概率水平下城市地震影响烈度在不同城市之间表现出较大变化，以50年超越概率2%作为城市特征地震影响烈度，可以作为城市地震防御烈度确定的依据，并据此对城市未来地震影响进行合理的描述.   相似文献   

高密度电法勘察岩土工程实例   总被引：6，自引：1，他引：6  

陈泉霖  陈新奇 《中国煤田地质》2004,16(6):52-54

利用岩土层间的导电性差异特性，使用由WDJD-1型主机与WDZJ-1多路电极转换器组成的高密度电法测量系统，按照不同的工程要求，采取不同的排列方式进行勘探，并用RES2DINV(演示版)高密度电阻率数据二维反演软件对所采集的数据处理解释，可实现对不同岩土层界面的划分。与常规电法相比，其方法手段更为先进，定性定量解释可靠，影像图件直观清晰。  相似文献