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61.
地壳应力场是地球动力学研究和地震孕育环境研究的重要基础资料.求解应力场的一种重要方法是根据断层擦痕资料反演,然而擦痕往往难以观测,但断层滑动性质也与应力场有紧密的关系,这部分资料十分丰富.本研究按照应力张量在断层面上的剪应力方向与擦痕滑动方向及断层滑动性质一致为准则提出了联合采用擦痕数据和定性断层滑动数据求解应力场的网格搜索法,并给出了反演参数的一定置信度下的置信区间.采用假定的走滑型、挤压型和拉张型应力张量产生由7个擦痕数据和80个定性断层滑动数据组成的三组数据集.采用这些人工合成数据求解应力张量的实验结果表明,该方法可以更为准确地反演应力张量参数,定性断层滑动资料的参与使得应力张量的主应力方向更加接近假定的主应力方向,并且,应力张量参数的不确定性大大减小.将该方法应用于乌鲁木齐附近的定量擦痕和定性断层滑动性质数据,得到该地区较为精确的应力张量.结果表明,乌鲁木齐主压应力方向为近南北向、主张应力方向近垂直向,应力形因子为0.03.该地区占主导地位的近东西向的逆冲断层是近南北向挤压和近垂直向拉张形成的.较低的应力形因子表明乌鲁木齐地区在南北向挤压并辅以博罗科努山和博格达山的东、西向挤压的应力状态下处于隆升状态. 相似文献
62.
63.
该文叙述了上海地区以粘性土为持力层的混凝土预制桩实测承载力低于理论计算值的现象,分析了产生此种现象的原因,提出了改进的具体措施。 相似文献
64.
The global positioning system (GPS) model is distinctive in the way that the unknown parameters are not only real-valued,
the baseline coordinates, but also integers, the phase ambiguities. The GPS model therefore leads to a mixed integer–real-valued
estimation problem. Common solutions are the float solution, which ignores the ambiguities being integers, or the fixed solution,
where the ambiguities are estimated as integers and then are fixed. Confidence regions, so-called HPD (highest posterior density)
regions, for the GPS baselines are derived by Bayesian statistics. They take care of the integer character of the phase ambiguities
but still consider them as unknown parameters. Estimating these confidence regions leads to a numerical integration problem
which is solved by Monte Carlo methods. This is computationally expensive so that approximations of the confidence regions
are also developed. In an example it is shown that for a high confidence level the confidence region consists of more than
one region.
Received: 1 February 2001 / Accepted: 18 July 2001 相似文献
65.
A daily rainfall occurrence process 总被引:1,自引:0,他引:1
A model for the periodic (annual cycle), discrete rainfall occurrence process is presented. Using this model the probabilistic properties of the process in -day intervals can be investigated. In such an interval the rainfall occurrence process is approximated by some stationary processa
t
,tIN. The processa
t
,tIN is described by the distributions of the lengths of wet and dry sequences. It is assumed that the lengths of successive wet and dry sequences are independent. For this process the distribution of the number of wet days in -day intervals is calculated. The model is fitted to 50-year rainfall data from Wroclaw, Poland. Rainfall amounts of 0.1, 1.0 and 2.0 mm are considered as thresholds defining a wet day. To estimate the distribution of the length of wet and dry sequences the family of Pascal distribution is chosen. 相似文献
66.
67.
加卸载响应比在Poisson模型下的随机分布 总被引:9,自引:2,他引:7
本文在地震的发生时间服从Poisson过程,而地震震级服从Gutenberg-Richter关系的前提下,对不同定义的加卸载响应比Y值的随机分布进行了探讨。结果表明:当在计算窗口的地震发生的期望数目较大(〉40)时,Y1 ̄Y5值的分布基本稳定,出现高加卸载响应比的概率极低。然而当计算窗口的地震期望数目过小时,Y2 ̄Y5值则变得不太稳定。也就是说,服从Poisson过程的地震序列,在计算窗口的地震期 相似文献
68.
广义极值分布理论在重现期计算的应用 总被引:3,自引:0,他引:3
在气候统计学上,常用Weibull、Gumbel、Frechet统计分布函数对极端气候要素的分布进行拟合,广义极值分布理论综合了以上三种极值分布模型,在气候分析中得到了广泛应用。以南昌市年汛期日最大降水量为例,利用广义极值分布理论对其分布进行拟合,并对重现值及其置信区间进行计算,为气候要素极值的统计分析提供了一种新的手段。 相似文献
69.
Real-time flood forecasting of the Tiber river in Rome 总被引:3,自引:2,他引:1
An adaptive, conceptual model for real-time flood forecasting of the Tiber river in Rome is proposed. This model simulates
both rainfall-runoff transformations, to reproduce the contributions of 37 ungauged sub-basins that covered about 30% of the
catchment area, and flood routing processes in the hydrographic network. The adaptive component of the model concerns the
rainfall-runoff analysis: at any time step the whole set of the model parameters is recalibrated by minimizing the objective
function constituted by the sum of the squares of the differences between observed and computed water surface elevations (or
discharges). The proposed model was tested through application under real-time forecasting conditions for three historical
flood events. To assess the forecasting accuracy, to support the decision maker and to reduce the possibility of false or
missed warnings, confidence intervals of the forecasted water surface elevations (or discharges), computed according to a
Monte Carlo procedure, are provided. The evaluation of errors in the prediction of peak values, of coefficients of persistence
and of the amplitude of confidence intervals of prediction shows the possibility to develop a flood forecast model with a
lead time of 12 h, which is useful for civil protection actions. 相似文献
70.
Kingshuk Roy Choudhury 《Mathematical Geosciences》2009,41(5):535-553
Finite strain estimation is a widely used technique for the study of rock deformation in structural geology. One particular
algorithm proposed by Shimamoto and Ikeda uses the ‘average shape matrix’ of deformed markers. This paper provides a detailed
error analysis for resulting strain estimates in two dimensions. When the number of markers exceeds 100, estimators of components
of the strain tensor are shown to have an approximately Gaussian distribution with variances that increase with their mean.
Equal variance estimators are obtained by applying a log transform for the elongation and an arcsin transformation for the
orientation estimates. Confidence interval formulae for strain tensor components are proposed. Lithology specific constants
arising in these formulae are estimated from undeformed samples. The results are validated by application to simulated data
as well as observational data from thin sections of sandstone sampled from SE Ireland. 相似文献