基于线性矩法的珠江三角洲区域洪水频率分析

采用线性矩法及珠江三角洲19个水位站近50a的年最高实测洪水位,在水文站点一致性分析及水文相似区鉴别的基础上,进行区域洪水频率计算及空间特征分析.结果表明:整个珠江三角洲可划分为3个水文相似区,其形成动力机制各不相同;3个水文相似区和非相似区的最佳分布函数各自不同;整个区域的洪水频率分布自上游(内河地区)到下游(沿海地区)逐渐减小,证明外海地区比上中游等其他地区面临更大的洪涝灾害威胁.     

基于线性矩法的东江流域区域枯水频率分析

线性矩法是在概率权重法基础上发展起来的一类分布函数参数确定方法．以年最小七日平均流量作为枯水径流的统计特征量，在水文站点一致性分析、水文相似区鉴别的基础上，以常见的5种三参数分布函数：Generalized Pareto分布（GPA）、Generalized Extreme-Value分布（GEV）、Generalized Logistic分布（GLO）、LogNormal分布（LN3）和Pearson type Ⅲ（PⅢ）为研究对象进行东江流域区域枯水频率分析．分析结果表明，LN3为最适合东江流域的区域枯水分布．将实测枯水流量与采用区域化方法所得到的枯水模拟结果进行对比分析，结果表明区域化所得到的模拟精度较高，可以满足实际需要．     

水文频率分析中的多项式正态变换方法研究

采用多项式正态变换(聊盯)方法,把偏态分布转换为正态分布,推求指定频率下正态分布的设计值(分位数),然后通过一一变换转换成原偏态分布对应频率的设计值．以P．Ⅲ型分布为例,用Monte-Carlo法进行模拟分析,并对PNT法的统计性能与线性矩(L广M)法的统计性能进行了比较．结果表明,PNT法的精度略差于L-M,g-ej精度．由于PNT法本质上是非参数估计方法,不需要假设水文变量的分布线型,因此该法理论上是一种较为可行的水文极值分析方法．     

可考虑历史洪水对数正态分布线性矩法的研究

简要介绍对正态分布线性矩与分布参数的关系，提出两种可考虑历史洪水的样本线性矩估计公式。统计试验结果表明，估计公式均具有较高精度。从两种估算公式中推荐一种效果更好的供实际频率计算使用，从而解决了具有历史洪水时对数正态分布的样本线性矩的计算问题。此外，对线性矩法与矩法、适线法作了对比分析，结果表明，线性矩法比矩法、适线法有较大的优越性，其不偏性能最好且具有良好的有效性。     

气候变化对衢州水文站洪水频率分析的影响

以衢州水文站为研究对象,针对衢州水文站的年最大值序列,选择广义极值分布作为该站洪水频率分析的分布函数,使用30a滑动平均法对线性矩估计所得分布函数参数的变化趋势进行分析,通过研究气候变化对衢州水文站洪水频率分析统计参数的影响来研究水文流量序列对气候变化的敏感程度.研究结果表明,气候变化对频率分析分布曲线的参数有较大影响,从而影响最终设计洪水的数值.     

皮尔逊-Ⅲ型频率曲线可视化程序开发

皮尔逊-Ⅲ型分布是我国水利水电工程水文计算规范中推荐采用的分布,现行广泛采用的是适线法。本文介绍了适线法的基本原理,利用Microsoft Visual Studio 2008软件平台开发了频率曲线可视化程序,可对一个系列的水文资料进行适线,以多种方式保存结果,计算速度快,可视化程度高,具有良好的精度、较强通用性,有一定的应用价值和教学意义。     

基于河流出水量的区域水文干旱特征及其水文频率分析——以黔中水利枢纽工程区为例

为了加强区域水文干旱预测预报系统,对区域水文干旱特征变化规律作进一步分析,基于河流出水量这一视角,以黔中水利工程区1960—2016年的逐月径流数据为基础,通过河流出水量估算,采用径流距平百分率及P-Ⅲ(PearsonⅢ)型曲线、适线法等水文频率分析法进行水文干旱特征研究。结果表明:近57年来,黔中水利工程区河流年出水量波动较大,1989年达到历史极低值,出水量总体呈递减趋势;水文干旱主要发生于黔中地区的中部区域,进入21世纪之后区域水文干旱发生得较为频繁,主要以中旱为主,各干旱程度的频率趋势依次为:轻旱中旱重旱特旱;根据P-Ⅲ型水文频率数学模型,河流出水量最小1个月低于52.70 m~3/s,最小3个月低于169.36 m~3/s,最小5个月低于313.90 m~3/s,最小7个月低于543.48 m~3/s时区域内发生20年一遇(P=95%)的水文干旱。     

东江流域枯水径流的频率分析

将线性矩法应用于东江流域由13个子流域所组成的研究区域。线性矩法具有良好的参数估计性能。利用广泛应用于枯水研究中的概率点据相关系数检验法,采用5种有效的统计特征量较为深入地分析了6种常用的三参数分布函数,即GEV、GLO、LN 3、GPA、P 3和LP 3分布的区域频率特性。概率点据相关系数检验法和四阶线性矩检验法的计算结果表明,当采用三参数对数正态分布(LN 3)作为研究区域上的枯水频率分布线型时,这5种统计特征量均为最优。因此,建议采用LN 3分布来确定东江流域年最小七日设计枯水流量。     

PWM法在水文线型假设检验中的应用

本文简述了目前水文计算中水文随机变量如洪峰，洪量等的概率分布函数的型式选择的理论和方法。在此基础上计算了当线型选为Ｐｅａｒｓｏｎ－Ⅲ型，以概率权重矩法估计其中参数时五个常用统计量的临界值表，同时用该表对僵５０个站点洪峰系列的分布线型进行了假设检验，并将检验结果与用适线法估计参数时的检验结果进行了对比，结果表明；采用Ｐ－Ⅲ型分布描述我国的洪峰系列是适合的。     

线性矩法在P-型参数估计中的应用

线性矩法(L-Moment)是在常规矩的基础上发展起来的估计洪水频率曲线参数值的一种新方法。为讨论它在洪水频率分析计算中的应用,就其在P-型分布下参数估计的算法,与传统参数估计方法在统计性能方面的差异进行分析计算。大量统计试验结果表明,线性矩法不偏性能最好且具有良好的有效性,不失为一种优良的参数估计方法。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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