共查询到19条相似文献,搜索用时 78 毫秒
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依据最大熵原理求解出地震震级和地震间隔时间的最可几分布和威布尔(Weibull)分布。以甘肃天祝为例,应用极值分布模型、对数正态分布模型和威尔分布模型以及K-S检验和直方图检验2种方法,分别对该地区实际地震数据进行检验。所得结果与理论求解结果一致。 相似文献
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《地震工程与工程振动》2015,(1)
基于阈值模型(POT)的广义帕累托分布(GPD)能充分利用样本中较大的观测值,在极值计算上有广泛的应用。本文讨论了广义Pareto分布以及该分布在风压极值计算中的应用。采用极大似然估计方法,对风压样本进行GPD拟合,得到具有一定保证率的风压极值。通过与峰值因子法(PFM)和经典极值方法(GEVD)计算的结果相比较,证明GPD拟合风压数据的效果较好,高保证率下的极值估计合理。对于高斯分布的风压样本,三种方法计算得到的结果比较接近;对于非高斯分布的样本,三种计算方法的结果存在较大差别,以GPD拟合的结果最优。应用GPD方法计算风压极值无需风压分布满足高斯假定,因而具有更广泛的适用性。 相似文献
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本文根据南北地震带的构造背景和地震活动的特点,从“多震点”的角度出发,运用极值理论等方法探讨了该带地震的时空强分布的统计规律。 相似文献
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在提出极值分布区间估计理论和方法和基础上,讨论了地震预报中的区间估计问题。文中以年最大地震震级分布服从Ⅲ型极值分布为例,介绍了区间估计地震预报中的应用。 相似文献
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地震作用的概率模型及其统计参数 总被引:55,自引:9,他引:55
本文对我国华北、西北、西南三个地区45个城镇地震危险性分析的结果进行了统计和检验,结果表明地震烈度的概率分布符合极值Ⅲ型。笔者用不同方法对地震烈度的极值Ⅲ型分布参数进行推断、估计,均得到满意的结果。文中还对地震作用的概率模型及其统计参数进行了分析,给出了实用的结果。 相似文献
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本文对川滇地区中、强震震源机制解和中小地震平均节面解分析,指出川滇地区现今构造应力场在北西-北西西向压应力作用下,以水平剪切错动为主。同时,采用极值理论、最大信息熵、线性预测和灰色理论等方法综合分析,预测川滇地区未来强震的趋势。 相似文献
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本文介绍了平稳序列穿过理论及其在预测强震趋势中的应用,并用我国天山地区、西藏地区及南北地震带的地震资料进行了检验,取得了较好的结果。同时也将用这种方法所得到的结果与传统的极值法所得到的结果进行了比较,结果表明使用这种方法对强震趋势的预报是有效的,而且具有一些极值法所没有的优点。 相似文献
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In climatology and hydrology, univariate Extreme Value Theory has become a powerful tool to model the distribution of extreme events. The Generalized Pareto Distribution (GPD) is routinely applied to model excesses in space or time by letting the two GPD parameters depend on appropriate covariates. Two possible pitfalls of this strategy are the modeling and the interpretation of the scale and shape GPD parameters estimates which are often and incorrectly viewed as independent variables. In this note we first recall a statistical technique that makes the GPD estimates less correlated within a Maximum Likelihood (ML) estimation approach. In a second step we propose novel reparametrizations for two method-of-moments particularly popular in hydrology: the Probability Weighted Moment (PWM) method and its generalized version (GPWM). Finally these three inference methods (ML, PWM and GPWM) are compared and discussed with respect to the issue of correlations. 相似文献
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超高密度电法是一种新的地球物理探测技术,它通过多通道数据采集和多装置数据联合反演,极大地提高了电法勘探的成像精度.本文提出一种主成分-正则化极限学习机(PC-RELM)非线性反演方法,该方法针对超高密度电法所获取的高维勘探数据进行反演建模,通过随机设定隐层参数来简化模型的学习过程,通过主成分分析方法来进行高维数据降维,最后引入正则化因子提高反演模型的泛化能力.论文给出了超高密度电法的原理、样本构造方法和非线性反演流程,使用交叉验证方法获得了优化的隐节点数目和正则化参数,构造了优化的反演模型.通过两个经典的超高密度模型的反演结果表明,该方法能够较好地解决超高密度电法反演的高维数据非线性建模问题,能够弥补单一装置数据反演的不足,同时相较其他的非线性反演方法(ELM,BPNN和GRNN)具有更加准确的反演结果. 相似文献
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The two-component extreme value distribution for flood frequency analysis: Derivation of a new estimation method 总被引:1,自引:0,他引:1
M. Fiorentino K. Arora V. P. Singh 《Stochastic Environmental Research and Risk Assessment (SERRA)》1987,1(3):199-208
The two component extreme value (TCEV) distribution has recently been shown to account for most of the characteristics of the real flood experience. A new method of parameter estimation for this distribution is derived using the principle of maximum entropy (POME). This method of parameter estimation is suitable for application in both the site-specific and regional cases and appears simpler than the maximum likelihood estimation method. Statistical properties of the regionalized estimation were evaluated using a Monte Carlo approach and compared with those of the maximum likelihood regional estimators. 相似文献
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T. R. Kjeldsen D. Rosbjerg 《Stochastic Environmental Research and Risk Assessment (SERRA)》2002,16(5):358-373
A comparison of different methods for estimating T-year events is presented, all based on the Extreme Value Type I distribution. Series of annual maximum flood from ten gauging
stations at the New Zealand South Island have been used. Different methods of predicting the 100-year event and the connected
uncertainty have been applied: At-site estimation and regional index-flood estimation with and without accounting for intersite
correlation using either the method of moments or the method of probability weighted moments for parameter estimation. Furthermore,
estimation at ungauged sites were considered applying either a log-linear relationship between at-site mean annual flood and
catchment characteristics or a direct log-linear relationship between 100-year events and catchment characteristics. Comparison
of the results shows that the existence of at-site measurements significantly diminishes the prediction uncertainty and that
the presence of intersite correlation tends to increase the uncertainty. A simulation study revealed that in regional index-flood
estimation the method of probability weighted moments is preferable to method of moment estimation with regard to bias and
RMSE. 相似文献
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Qian Lu Shijie Wang Xiaoyong Bai Fang Liu Shiqi Tian Mingming Wang Jinfeng Wang 《Acta Geochimica》2020,(1):116-126
In near-infrared spectroscopy,the traditional feature band extraction method has certain limitations.Therefore,a band extraction method named the three-step extraction method was proposed.This method combines characteristic absorption bands and correlation coefficients to select characteristic bands corresponding to various spectral forms and then uses stepwise regression to eliminate meaningless variables.Partial least squares regression(PLSR)and extreme learning machine(ELM)models were used to verify the effect of the band extraction method.Results show that the differential transformation of the spectrum can effectively improve the correlation between the spectrum and nickel(Ni)content.Most correlation coefficients were above 0.7 and approximately 20%higher than those of other transformation methods.The model effect established by the feature variable selection method based on comprehensive spectral transformation is only slightly affected by the spectral transformation form.Infive types of spectral transformation,the RPD values of the proposed method were all within the same level.The RPD values of the PLSR model were concentrated between 1.6 and 1.8,and those of the ELM model were between 2.5 and2.9,indicating that this method is beneficial for extracting more complete spectral features.The combination of the three-step extraction method and ELM algorithm can effectively retain important bands associated with the Ni content of the soil.The model based on the spectral band selected by the three-step extraction method has better prediction ability than the other models.The ELM model of the first-order differential transformation has the best prediction accuracy(RP^2=0.923,RPD=3.634).The research results provide some technical support for monitoring heavy metal content spectrum in local soils. 相似文献
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Methods for estimating the magnitude of extreme floods are reviewed. A method which combines a probabilistic storm transposition technique with a physically-based distributed rainfallrunoff model is described. Synthetic storms with detailed spatial and temporal distributions are generated and applied to the calibrated model of the Brue river basin, U.K. (area 135 km2). The variability of catchment response due to storm characteristics (storm area, storm duration, storm movement, storm shape and within storm variation) and initial catchment wetness conditions is investigated. A probabilistic approach to estimating the return periods of extreme catchment responses is suggested. 相似文献
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ABSTRACTThere is a lack of suitable methods for creating precipitation scenarios that can be used to realistically estimate peak discharges with very low probabilities. On the one hand, existing methods are methodically questionable when it comes to physical system boundaries. On the other hand, the spatio-temporal representativeness of precipitation patterns as system input is limited. In response, this paper proposes a method of deriving spatio-temporal precipitation patterns and presents a step towards making methodically correct estimations of infrequent floods by using a worst-case approach. A Monte Carlo approach allows for the generation of a wide range of different spatio-temporal distributions of an extreme precipitation event that can be tested with a rainfall–runoff model that generates a hydrograph for each of these distributions. Out of these numerous hydrographs and their corresponding peak discharges, the physically plausible spatio-temporal distributions that lead to the highest peak discharges are identified and can eventually be used for further investigations.
Editor A. Castellarin; Associate editor E. Volpi 相似文献
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This note points out a problem with the way in which extreme value distributions have been fit to the intensities of the largest geomagnetic storms per solar cycle. An alternative method is described. This method is applied to observations of the three largest geomagnetic storms in solar cycles 11–22. 相似文献
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The greatest one-day rain amounts recorded at individual stations in the country during the last 41-year period from 1940 onwards were examined for all observatories as well as State rain-gauge stations in an attempt to bring out up-to-date information on the greatest recorded point rainfall for the duration of one day. Outstanding one-day point rainfall amounts recorded prior to 1940 were also examined and have been included in this note along with their date and year of occurrence by way of comparison. A generalized chart has been prepared based on the percentage ratios of the greatest one-day rainfall to the mean annual rainfall of about 300 observatory stations distributed uniformly over the entire country. On the basis of Depth-Area-Duration (DAD) analyses of the most severe rainstorms which occurred over different plain areas of the country, it has been found that the 2 July, 1941, rainstorm gave the highest areal rain depths in the country for different areas. Comparison with similar areal rain depths of the tropical USA has shown that rain depths of the July, 1941, rainstorm were higher for all areas excepting the areas of 500 sq. miles (1295 sq. km) and 1000 sq. miles (2590 sq. km). 相似文献