共查询到20条相似文献，搜索用时 62 毫秒
1.
线性矩法估计参数的保证修正值系数B的推求 总被引：3，自引：0，他引：3
在设计洪水的抽样误差估计中,采用保证修正值系数B方法估计均方差简单易用。应用线性矩法估计频率分布曲线的参数,有较好的无偏性和有效性,具有一定的应用前景。目前线性矩法的B值诺模图尚未确定,给用线性矩法确定参数时估计抽样误差带来了难度与不便。采用统计试验,分析了离差系数、偏态系数和样本长度对B值的影响,结果表明线性矩法估计参数时仍可采用保证修正值系数B值诺模图方法来估计抽样误差,并推求了不同偏态系数、设计频率情形下的B值,制成了线性矩法的B值诺模图备用。 相似文献
2.
介绍了基于水文气象途径的地区线性矩法的概念,通过基于次序统计量的线性矩进行参数估计与基于水文气象一致区的地区分析法相结合,以太湖流域1d时段的年极值降雨资料为例,进行暴雨频率分析。应用水文气象一致区的判别准则,将太湖流域划分为8个水文气象一致区;综合考虑三种拟合优度检测方法,选择1~8区的最优分布线型分别为:GEV、GLO、GEV、GEV、GNO、GNO、GEV、GNO;根据地区分析法原理,估算各雨量站的暴雨频率设计值。分析表明:太湖流域各重现期下的年极值降雨空间分布形态基本一致,西南山区是太湖流域的暴雨高风险区,应该在地区防洪规划中引起重视。结果表明:地区线性矩法具有很高的学术和实用价值,建议在全国范围内推广,作为防洪规划的顶层设计和基础工作,以满足工程防洪设计、地区防洪规划、山洪预警和城市防涝防洪规划等方面的需求。 相似文献
3.
关于线性矩法与概率权矩法同解关系的分析研究 总被引：2，自引：3，他引：2
对线性矩法与概率权矩法进行了分析，认为线性矩法与概率权矩法对统计参数估计的结果是一致的，它们之间具有同解关系，其计算结果略存在的差异乃是由于采用不同近似公式的计算误差所致。 相似文献
4.
以淮河流域为研究区,利用地区线性矩法进行站点极值降雨的频率分析。研究结果表明:基于气象成因和水文统计特性相结合的方法将研究区划分为6个通过异质性和不和谐性检测的水文气象一致区。在此基础上,通过蒙特卡罗模拟、均方根误差和线性矩系数的相关图综合判断得出各时段下6个一致区下的最优分布。其中,24h时段下的最优分布分别为:GEV、GNO、GLO、GEV、GLO、GEV。利用最优分布计算出淮河流域各站点一整套(多时段多重现期)的频率估计值。其中,最大值分布在沂蒙山区,这与站点的实际观测相一致。水文气象分区线性矩法是一种稳健可靠的频率分析方法,可应用于其它流域。 相似文献
5.
可考虑历史洪水信息的广义极值分布线性矩法的研究 总被引：3，自引：1，他引：2
在水文及其他行业中广义极值分布(GEV)是一种较为常用的分布线型,包括极值Ⅰ型、极值Ⅱ型和极值Ⅲ型分布.在介绍了该分布线性矩与其参数关系后,给出了有效的可以考虑历史洪水信息的线性矩公式,并对由线性矩推求分布密度函数中k值作了改进.通过统计试验计算分析了线性矩在该分布中的统计性能及历史洪水公式的适用性,并与绝对值准则和平方和准则两种不同优化适线法、矩法作了比较.统计试验表明,改进k值计算后的线性矩法略优于传统线性矩法.从总体上讲,改进k值计算后的线性矩法优于平方和准则适线法及矩法,其参数及设计值的不偏性很好,与绝对值准则适线法总体上相当. 相似文献
6.
地区线性矩法(Regional L-moments Analysis,RLMA)是目前最先进的频率估算方法之一,自20世纪90年代起被广泛应用于美国及其他一些国家的防洪设计标准的分析计算中;我国近年也在太湖流域暴雨频率分析中成功地采用推广了这一水文气象途径的频率计算方法,积累了实际经验。但是,由于地面雨量站点有限、资料长度有限以及站点空间分布的不均匀等问题,研究区中相邻水文气象一致区之间暴雨频率估算值会出现空间不连续性的现象,这个空间不一致的问题尚没有得到合理的解决。在简要介绍地区线性矩法推求频率估计值的基础上,着重讨论并介绍一种概念清楚、简单易操作的基于空间往返二次内插的校正方法,来解决频率估算值空间不连续的问题。这种空间内插平差主要通过构造一个与研究区实测站点控制面积相应分辨率的虚拟网格站网来实现。研究结果表明,经过平差后校正的研究区内各站点的频率估计值的经验频率与理论概率更加接近,频率估计值的空间分布也更加合理。 相似文献
7.
线性矩法的特点评析和应用问题 总被引：1，自引：1，他引：1
介绍了线性矩法的无偏估计与直接计算的关系，讨论了在概率权重矩计算过程中各系列之间的高度相关性及其对结果的影响，建立了直接计算线性矩法的Cv和Cs近似公式，叙述了适线问题和相应的经验频率公式。文中认为，水文频率计算时，由于资料的随机性和处理方法上的概化性，故用任何计算方法得到的结果，具有不同程度的不确定性，只能作为估计的初值，需通过时空上综合平衡，再经合理性分析和调整后，才能取用。 相似文献
8.
矩、概率权重矩与线性矩的关系分析 总被引：2，自引：5，他引：2
本文叙述了矩、概率权重矩与线性矩之间的关系，并以Г分布为例进行分析。线性矩的计算式为概率权重矩的线性组合，两者的计算结果完全相同。概率权重矩和线性矩均与指定的频率分布型式和作为权重的概率有关，结果的敏感性较差。详细分析了计算参数的近似公式及其精度。对水文应用而言，它们的计算结果仅是估计的初值，需经过合理性分析才能取用。 相似文献
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根据太湖流域96个雨量站年最大日雨量资料进行分析计算,在线性矩中当采用绘点公式Pi∶n=(i+A)/(n+B),BA-1时,选取不同参数A和B的值,通过蒙特卡洛模拟方法 ,计算实际资料频率估计值与生成资料频率估计值的平均值的均方根误差来探讨不同绘点公式对频率估计值的影响。一般认为A=0,B=0时,线性矩估算是无偏的。重点讨论当估计稀遇频率事件时,A=0,B=0是否仍然恰当;如若不是,A和B取什么值是最佳的组合。结果表明:在线性矩参数估计中对常遇频率估计值采用无偏绘点公式时频率估计值不确定性很小,而对稀遇频率估计值采用无偏绘点公式计算存在较大的不确定性。比较了不同绘点公式对太湖流域年最大日雨量100-y,1 000-y,10 000-y频率估计值的影响,发现在线性矩参数估计中对稀遇频率估计值稳健性表现最好的绘点公式是Pi∶n=(i-0.35)/n,即A=-0.35,B=0。 相似文献
11.
Emily Keeble David I. Whiteside Michael J. Benton 《Proceedings of the Geologists' Association. Geologists' Association》2018,129(2):99-119
Pant-y-ffynnon Quarry in South Wales yielded a rich cache of fossils in the early 1950s, including articulated specimens of new species (the small sauropodomorph dinosaur Pantydraco caducus and the crocodylomorph Terrestrisuchus gracilis), but no substantial study of the wider fauna of the Pant-y-ffynnon fissure systems has been published. Here, our overview of existing specimens, a few described but mostly undescribed, as well as freshly processed material, provides a comprehensive picture of the Pant-y-ffynnon palaeo-island of the Late Triassic. This was an island with a relatively impoverished fauna dominated by small clevosaurs (rhynchocephalians), including a new species, Clevosaurus cambrica, described here from a partially articulated specimen and isolated bones. The new species has a dental morphology that is intermediate between the Late Triassic Clevosaurus hudsoni, from Cromhall Quarry to the east, and the younger C. convallis from Pant Quarry to the west, suggesting adaptive radiation of clevosaurs in the palaeo-archipelago. The larger reptiles on the palaeo-island do not exceed 1.5?m in length, including a small carnivorous crocodylomorph, Terrestrisuchus, and a possible example of insular dwarfism in the basal dinosaur Pantydraco. 相似文献
12.
Gilles Serge Odin 《Comptes Rendus Geoscience》2002,334(6):409-414
Lithostratigraphy, physicochemical stratigraphy, biostratigraphy, and geochronology of the 77–70 Ma old series bracketing the Campanian–Maastrichtian boundary have been investigated by 70 experts. For the first time, direct relationships between macro- and microfossils have been established, as well as direct and indirect relationships between chemo-physical and biostratigraphical tools. A combination of criteria for selecting the boundary level, duration estimates, uncertainties on durations and on the location of biohorizons have been considered; new chronostratigraphic units are proposed. The geological site at Tercis is accepted by the Commission on Stratigraphy as the international reference for the stratigraphy of the studied interval. To cite this article: G.S. Odin, C. R. Geoscience 334 (2002) 409–414. 相似文献
13.
The effect of water on accessory phase solubility in subaluminous and peralkaline granitic melts 总被引：4，自引：0，他引：4
The solubilities of columbite, tantalite, wolframite, rutile, zircon and hafnon were determined as a function of the water contents in peralkaline and subaluminous granite melts. All experiments were conducted at 1035 °C and 2 kbar and the water contents of the melts ranged from nominally dry to approximately 6 wt.% H2O. Accessory phase solubilities are not affected by the water content of the peralkaline melt. By contrast, solubilities are affected by the water content of the subaluminous melt, where the solubilities of all the accessory phases examined increase with the water content of the melt, up to 2 wt.% H2O. At higher water contents, solubilities are nearly constant. It can be concluded that water is not an important control of accessory phase solubility, although the water content will affect diffusivities of components in the melt, thus whether or not accessory phases will be present as restite material. The solubility behaviour in the subaluminous and peralkaline melts supports previous spectroscopic studies, which have observed differences in the coordination of high field strength elements in dry vs. wet subaluminous granitic glasses, but not for peralkaline granitic glasses. Lastly, the fact that wolframite solubility increases with increasing water content in the subaluminous melt suggests that tungsten dissolved as a hexavalent species. 相似文献
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Muriel Rocher Stéphane Baize Stéphane Jaillet Edward Marc Cushing Yannick Lozac&#x;h Francis Lemeille 《Comptes Rendus Geoscience》2003,335(8):701-708
Calcite samples were extracted both from the rock matrix and the superficial coating of a karstified fault plane of an underground quarry, located in the eastern border of the Paris basin. The karstification is dated as Quaternary. Analysis of mechanical calcite twinning reveals that only the calcite matrix has also undergone a compression trending WNW that can be attributed to the Mio-Pliocene alpine collision. Both coating and matrix have undergone a strike-slip regime with σ1 roughly trending north–south, that could correspond to the regional present-day state of stress, a strike-slip compression rather trending NNW, modified by local phenomena. To cite this article: M. Rocher et al., C. R. Geoscience 335 (2003). 相似文献
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正20141520 Bo Ying(Key Laboratory of Metallogeny and Mineral Assessment,MLR,Beijing 100037,China);Liu Chenglin Saline Spring Hydrochemical Characteristics and Indicators for Potassium Exploration in Southwestern and Northern Tarim Basin,Xinjiang(Acta Geoscientica Sinica,ISSN1006-3021,CN11-3474/P,34(5),2013,p.594-602,5 illus.,3 tables,28 refs.) 相似文献
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正20141243Chen Ge(Hangzhou Research Institute of Petroleum Geology,PetroChina,Hangzhou 310023,China);Si Chunsong Study on Sedimentary Numerical Simulation Method of Fan Delta Sand Body(Journal of Geology, 相似文献
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正20142599Chen Sanming(Guangxi Key Laboratory of Concealed Deposits Exploration,Guilin University of Technology,Guilin541004,China);He Yuzhou Block Model and Reserves Estimation of Panzhihua Iron Deposit Based on 3D Geological Modeling(Journal of Guilin University of Technology,ISSN1674-9057,CN45-1375/N,33(4),2013,p.610-615,9illus.,1table,15refs.) 相似文献
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正20140594 Bai Daoyuan(Hunan Institute of Geology Survey,Changsha 410016,China);Zhong Xiang Faults in the Jingzhou Basin and Their Tectonic Settings(Geotectonica et Metallogenia,ISSN1001-1552,CN44-1595/P,37(2),2013,p.173-183,6illus.,59refs.)Key words:basin evolution,tectonic setting,South China In the Upper Paleozoic and Jurassic se- 相似文献
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正20141912Cao Hui(State Key Laboratory for Continental Tectonics and Dynamics,Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China)Gravitational Collapse and Folding during Orogenesis:A Comparative Study of FIA Trends and Fold Axial Plane Traces(Geology in China,ISSN1000-3657,CN11-1167/P,40(6),2013,p.1818-1828,9illus.,35refs.,with 相似文献