随机AMR模型的参数估计及其在几次强震中的应用   总被引：1，自引：1，他引：1       下载免费PDF全文

王丽凤  马丽  陈时军 《地震学报》2004,26(2):162-173

通过模拟强震前累积应变能释放具有加速特征地震目录的方法，系统地研究了随机AMR模型参数估计特征．在此基础上，应用AIC（Akaikes information criteria）准则，分别对中国和新西兰几次强震加速情况进行了考察，分析强震前地震活动类型， 有无加速，及何种因素引起的加速，同时探讨加速活动的区域分布特征和预测未来强震发生时间的可能途径．   相似文献   

The thermal regime of the Northeastern-German Basin from 2-D inversion   总被引：2，自引：0，他引：2  

Hans-Dieter Vosteen  Volker Rath  Andreas Schmidt-Mumm  Christoph Clauser   《Tectonophysics》2004,386(1-2):81-95

The thermal regime and the distribution of heat flow at the base of sedimentary basins is fundamental to the understanding of the process of basin evolution and the associated mobilization and migration of hydrocarbon and other fluids. For the Northeastern-German sedimentary basin, available information on structure, temperature, and thermal properties along a seismic DEKORP reflection profile allow high resolution 2-D forward and inverse simulations. This approach is attractive in situations where much information is available, if only with considerable uncertainty. In particular, this allows to introduce “soft” information into the analysis. In our case, forward simulations yield initial a priori estimates of the parameters while inversion calculations yield a posteriori estimates of the parameters and their uncertainty. The a priori parameters as well as their assumed uncertainty are input for a Bayesian parameter estimation scheme. In respect to the Northeastern-German sedimentary basin, the inverse analysis postulates a significant and characteristic a posteriori variation of thermal conductivity of the Zechstein unit along the entire profile as well as a generally large a posteriori thermal conductivity of the (pre-Permian) basement in the northern part of the basin. For inverse calculations, we used two alternative scenarios: One assumes the thermal conductivity of the Zechstein unit to be homogeneous along the profile while the other allows a lateral variation. A posteriori heat flow across the base of the model varies from 40 to 60 and 50 to 65 mW m⁻² for models in which values for thermal conductivity and radiogenic heat generation rate were either based on literature values or direct measurements, respectively.  相似文献   

Availability of Bauxite Reserves     

Meyer  F. M. 《Natural Resources Research》2004,13(3):161-172

Based upon a large database, this paper analyzes the record of bauxite mine production, exploration success, and resource depletion and evaluates the availability of bauxite reserves in the near future. The record clearly shows that for the past 50 years world bauxite production rose by an annual increase of over 5% while per capita consumption rose during the same period by about 4%. Time trends of the world bauxite reserve life index (RLI); that is, known world reserves of a given year divided by world production of the same year, are episodic and seem to follow bauxite price cycles. The present-day RLI indicates adequate bauxite supply for about 180 years and is the same as it was in 1950. However, if an annual growth rate of 5% is considered, the currently known reserves will be exhausted within the next 20 years and the reserve base will be adequate for not more than 25 years. This scenario is based, of course, on the unrealistic assumption that future exploration efforts fail to discover additional reserves. Evaluation of the quality, in terms of bauxite signatures, and quantity of presently known bauxite prospects that may be mined in future suggests that there is sufficient potential for adequate bauxite supply for the next 20 to 25 years at least. Bauxite signatures cover a wide range of values that allows selection of the most favorable bauxite prospects for future mining, both in economic as well as environmental terms. Although, there is the general believe that the world abundance of bauxite resources will ensure sufficient supply to meet future demands significant additional reserves have to be discovered if exponential growth rates continue. As the question of future bauxite supply is subject to economic and geologic principles one has to take into consideration that increasing exploration maturity in many mineral provinces will make it difficult to locate additional bauxite reserves and that decreasing real commodity prices will influence the level of investment in bauxite exploration.  相似文献   

Uncertainty Estimate in Resources Assessment: A Geostatistical Contribution   总被引：2，自引：0，他引：2  

de Souza  Luis Eduardo  Costa  João Felipe C. L.  Koppe  Jair C. 《Natural Resources Research》2004,13(1):1-15

For many decades the mining industry regarded resources/reserves estimation and classification as a mere calculation requiring basic mathematical and geological knowledge. Most methods were based on geometrical procedures and spatial data distribution. Therefore, uncertainty associated with tonnages and grades either were ignored or mishandled, although various mining codes require a measure of confidence in the values reported. Traditional methods fail in reporting the level of confidence in the quantities and grades. Conversely, kriging is known to provide the best estimate and its associated variance. Among kriging methods, Ordinary Kriging (OK) probably is the most widely used one for mineral resource/reserve estimation, mainly because of its robustness and its facility in uncertainty assessment by using the kriging variance. It also is known that OK variance is unable to recognize local data variability, an important issue when heterogeneous mineral deposits with higher and poorer grade zones are being evaluated. Altenatively, stochastic simulation are used to build local or global uncertainty about a geological attribute respecting its statistical moments. This study investigates methods capable of incorporating uncertainty to the estimates of resources and reserves via OK and sequential gaussian and sequential indicator simulation The results showed that for the type of mineralization studied all methods classified the tonnages similarly. The methods are illustrated using an exploration drill hole data sets from a large Brazilian coal deposit.  相似文献   

Including prior information in the estimation of effective soil parameters in unsaturated zone modelling   总被引：2，自引：0，他引：2  

J Mertens  H Madsen  D Jacques 《Journal of Hydrology》2004,294(4):251-269

In this paper we propose a methodology to include prior information in the estimation of effective soil parameters for modelling the soil moisture content in the unsaturated zone. Laboratory measurements on undisturbed soil cores were used to estimate the moisture retention curve and hydraulic conductivity curve parameters. The soil moisture content was measured at 25 locations along three transects and at three different depths (surface, 30 and 60 cm) on an 80×20 m hillslope for the year 2001. Soil cores were collected in 84 locations situated in three profile pits along the hillslope. For the estimation of the effective soil hydraulic parameters the joint probability distribution of measured parameter values was used as prior information. A two-horizon single column 1D MIKE SHE model based on Richards' equation was set-up for nine soil moisture measurement locations along the middle transect of the hillslope. The goal of the model is to simulate the soil moisture profile at each location. The shuffled complex evolution (SCE) algorithm has been applied to estimate effective model parameters using either wide parameter ranges, referred to as the ‘no-prior’ case, or the joint probability distribution of measured parameter values as prior information (‘prior’ case). When the prior information is incorporated in the SCE optimisation the goodness-of-fit of the model predictions is only slightly worse compared to when no-prior information is incorporated. However, the effective parameter estimates are more realistic when the prior information is incorporated. For both the no-prior and prior case the generalised likelihood uncertainty estimation procedure (GLUE) was subsequently used to estimate the uncertainty bounds (UB) on the model predictions. When incorporating the prior information more parameter sets were accepted for the estimation of the predictive uncertainty and the parameter values were more realistic. Moreover, UB better enclosed the observations. Thus, incorporating prior information in GLUE reduces the amount of model evaluations needed to obtain sufficient behavioural parameter sets. The results indicate the importance of prior information in the SCE and GLUE parameter estimation strategies.  相似文献   

Parameter estimation of the stochastic AMR model and its application to the study of several strong earthquakes     

王丽凤  马丽  陈时军 《地震学报(英文版)》2004,17(2):177-189

Introduction According to many published papers, seismicity in time-space domain shows some characteristics, such as doughnut epicenter distribution (Mogi, 1969) or quiescence of seismic activity before large earthquakes (WANG, et al, 2002), and aftershock decay (Ogata, 1998). In recent years, more and more seismologists (Lynnr, Steven, 1990) have found that many strong earthquakes are preceded by enhancing regional seismicity and accelerating strain energy release (ZHANG, et al, 2001). T…  相似文献   

基于变异函数模型的单裂隙张开度的随机模拟     

吴蓉  周志芳 《水文》2004,24(3):1-3,45

借助变异函数的优点，即能够反映区域化变量张开度的空间变化相关性和随机性特征,利用Kriging方法对单裂隙中张开度进行估值，由交叉验证法的拟合结果认为估值结果较为合理，并且通过溶质运移试验验证了Kriging法对单裂隙张开度的估值是可行的。  相似文献   

山西墨镫-左权铁路南段地质灾害危险性模糊综合预测评价   总被引：2，自引：0，他引：2  

汪玉松  朱才宝  周爱国  李亚伟 《陕西地质》2004,22(2):84-88

新建铁路工程用地地质灾害危险性评估的特点往往是地质灾害的种类多，影响因素复杂，常规方法不易客观定量的体现各区段在危险性方面的差异。本文在介绍模糊综合评价法基础上，结合实例探讨了模糊综合评价法在新建铁路工程用地地质灾害危险性评价中的应用。  相似文献   

瞬态面波预测单桩承载力模型研究     

武炜  张献民  杨进  曹金凤 《物探与化探》2004,28(1):88-91

总结了现有单桩竖向承载力检测技术存在的一些问题,结合实例提出了一种预测单桩承载力的间接方法———瞬态面波法。剪切波速与标贯击数之间也存在着相关关系,通过标贯击数建立起剪切波速与桩侧摩阻力及桩端阻力的相关模型,应用瞬态面波测试技术可快速检测桩周土剪切波速,确定单桩承载力。  相似文献   

An Idealized Mean Wind Profile for the Atmospheric Boundary Layer     

John D. Wilson  Thomas K. Flesch 《Boundary-Layer Meteorology》2004,110(2):281-299

We test a flexible, idealized mean wind profile for the loweratmosphere that can easily be matched to whatever windobservations may be available. Its intended function is to providea `best guess' wind profile from limited observations, e.g., foruse in dispersion models, and to this end, following earlierauthors, we have matched a Monin–Obukhov layer to a baroclinic Ekman layer.To demonstrate the flexibility of the two-layer wind profile, weoptimize its free parameters to provide best interpolative fits toa sample of multi-level wind profiles. These include model windprofiles extracted from the Canadian Global EnvironmentalMulti-scale weather model (GEM), as well as experimental profilesfrom the Wangara experiment, and from an over-ocean dispersionexperiment (LROD). In most cases the two-layer profile fit issatisfactory.  相似文献