基于非参数核密度估计的年径流频率计算

以陕北地区7个水文站的年径流频率计算为例,对比分析了非参数核密度估计与P-Ⅲ型及对数P-Ⅲ型两种参数模型的误差。结果表明:核密度估计具有较好的统计特性、精度和稳健性;LSCV法是计算最佳窗宽的一种较为理想的方法;非参数核密度估计拟合实测资料的能力优于参数模型。     

多因素耦合的内河限制性航道维护底宽确定方法

航道维护底宽是内河航道养护管理工作的重要指标之一。为探究限制性航道维护底宽的确定方法,基于航海学和可靠性理论,分析计算了满足通航标准、船舶运动特性、航行可靠性的航道底宽,构建了内河限制性航道维护底宽的效益-费用模型。其中效益模型由船舶运输、节能减排、替代公路运输以及防洪等效益构成,费用模型由一次性疏浚及日常维护等费用构成。在此基础上,耦合多因素综合分析计算了京杭运河镇江段的航道维护底宽,结果表明该航段40 m维护底宽较为合理。该限制性航道维护底宽确定方法较好地考虑了内河限制性航道多因素多目标需求,具有较高实用价值。     

自适应神经模糊系统的地基承载力组合模型

 碎石桩为处理软基的常用方法之一，其承载力除用静荷载试验确定外，一般用经验公式计算。但目前各公式采用的方法与理论依据不同，涉及的物理力学参数各有所侧重，难以反映诸多因素对承载力的影响。为克服单个模型(经验公式)的局限性与不确定性，在MATLAB环境下，采用非线性映射能力的自适应神经模糊推理系统(ANFIS)建立了碎石桩复合地基承载力组合模型。实例分析表明，组合模型预测相对误差小于3%，优于各子模型，其精度满足工程应用要求，为确定地基承载力提供了一种新的方法。     

基于MCMC的新安江模型参数不确定性分析及应用

针对新安江模型参数不确定性分析过程中出现的参数多、收敛慢、计算负担重等问题，提出基于MCMC方法的新安江模型参数不确定性分析，该方法通过Markov链MonteCarlo抽样方法求解得到模型各参数后验分布，显著提高了算法的计算速度和求解质量。参数后验分布结果为区间预报提供了条件，实例研究表明，以该结果进行不确定预报是可行的。     

宽顶堰式首部取水结构的泄水能力

为估算宽顶溢流堰的泄水能力， 需考虑多种因素， 但如此多的因素不宜采用某一种定律、方法或原则进行计算， 故需通过实验研究来解决这个问题。采用溢流堰模型进行了实验，并根据实验结果得出了新的计算图表及关系式， 用于计算其泄水能力。     

一种基于X型宽尾墩体型参数设计的方法

宽尾墩体型特征参数一般通过水工模型试验论证确定，但在模型试验开始前，为避免大量重复制作模型，浪费人力、物力和财力，可对宽尾墩体型进行初步设定，再通过模型试验进行适当调整，可大大缩短水工模型试验周期。本文通过查阅大量宽尾墩体型设计资料，并结合水工模型试验经验，介绍了一些基于X型宽尾墩体型设计经验参数的确定，为日后类似工程宽尾墩设计提供一定的参考。     

滑带土强度参数的人工神经网络预测

 利用改进BP网络技术，提出了确定滑带土强度参数的新方法。分析了滑带土强度参数的影响因素，并以收集的部分滑坡的实际数据作为训练和模型检验样本，采用动量法进行训练建立预测模型。模型检验表明，训练的模型具有较高的精度。该方法在确定清江水布垭古树包滑坡滑带土强度参数中效果较好，所得数据与其它常规方法综合确定的参数基本一致。     

概念性流域水文模型参数校准

为快捷有效地确定流域水文模型参数,梳理了水文模型参数校准的基本流程,文中阐述了各环节需关注的要点,重点探讨了参数优选过程中所需实测洪水数据的遴选原则及目标函数的设定,提出了一种组合型的目标函数,将多目标参数优化问题转化为单目标优化问题,使产、汇流参数优选同步进行,简化了参数优选过程,与其他多目标优化算法相比,更简单有效。本文以基于新安江模型的云峰水库入库洪水预报模型的参数校准为实例,对模型参数进行了校准,模拟结果达到了较高的精度,验证了参数校准方法的有效性。     

宽浅渠道糙率系数的确定

通过整理目前计算宽浅渠道糙率的计算方法,分析了宽浅渠道糙率的影响因素,通过模型计算,验证了宽浅渠道糙率系数的确定方法与过程。     

渗流分析中排水孔模拟复合单元法的参数研究

复合单元法是一种求解含排水孔渗流场的新方法，它将排水孔虚含于常规岩石单元内部，并为之建立新的计算模型，分析表明：该方法避免了在数据前处理工作中绘制细小、繁多的排水孔和其与岩石单元间的过渡单元，为含排水孔结构的渗流计算提供了很大的方便，具有较高的实用价值，针对该方法应用时涉及到的不确定参数取值问题，本通过算例给出含不同形式有压排水孔渗流场计算时复合单元界面参数取值规律，以利工程应用。     

Call for Papers

正As the eldest and most distributed professional journal of water industry,Water Wastewater Engineering(W WE)gained very wide acceptance from the colleagues working in this field in this country since start publication in 1964.Now it is administrated by the Ministry of Construction of the People’s Republic of China and sponsored by the China Civil Engineering Society etc.     

库水波动下库岸边坡地下水浸润线解析解及误差分析

解析法是库岸边坡地下水浸润线计算中便于实际应用的方法,但该方法须基于若干假定并对潜水运动基本方程线性化后才能求解。针对各假定和线性化过程建立不同的地下水渗流数学模型,用解析法和有限元法解答上述数学模型,分析各误差大小及其规律。结果表明:库岸垂直处理带来的误差要小于方程线性化处理和不考虑非饱和渗流带来的误差,而且它们都随渗透系数变大而减小;在三峡库区库水调度情况下,假定库水位等速变化带来的误差对大多岸坡而言可以忽略;计算库岸边坡地下水浸润线时,解析法只适用于水位变化幅度相比含水层厚度较小,且几何边界规则、岩土结构简单、岩土体渗透性较好时的情况。     

Changes in Summer Irrigated Crop Area and Water Use in Southeastern Turkey from 1993 to 2002: Implications for Current and Future Water Resources

Changes in summer irrigated cropland acreage and related water use are estimated from satellite remote sensing and ancillary data in semi-arid Southeastern Turkey where traditionally dry agricultural lands are being rapidly transformed into irrigated fields with the help of water from the Euphrates-Tigris Rivers. An image classification methodology based on thresholding of Landsat NDVI images from the peak summer period reveals that the total area of summer irrigated crops has increased three-fold (from 35,000 ha to over 100,000) in the Harran Plain between 1993 and 2002. Coupled analysis of annual irrigated crop area from remote sensing and potential evapotranspiration based estimates of irrigation water requirements for cotton indicate a corresponding increase in agricultural water use from about 370 million cubic meters to over one billion cubic meters, a volume in accordance with the state estimates. These estimates have important implications for understanding the rapid changes in current agricultural withdrawals in Southeastern Turkey and form a quantitative basis for exploring the changes in future water demands in the region. For example, expansion of irrigated lands have led to a steady decrease in potential evaporation due to increased roughness and decreased humidity deficit in the Harran Plain. Assuming that the changes in future evaporation conditions will be of similar nature, water use for irrigation is expected to decrease over 40 percent in future irrigation sites. Incorporating this decrease in overall planning of the irrigation projects currently under construction should lead to improved management, and by extension, sustainability of water resources in the region.     

Site modelling methods for detecting hydrologic alteration of flood frequency and flood duration in the floodplain below the carlyle dam,lower Kaskaskia River,Illinois, USA

Reports concerning the influence of dams on river hydrology vary among researchers, interest groups and government agencies. These often contradicting statements may occur because changes in hydrology caused by dams are distinct for each dam and river watershed. The objective of this research was to use site specific techniques to determine if the 1967 installation of the Carlyle Dam, lower Kaskaskia River, Illinois, altered flood frequency and duration within the forested floodplain located below the dam. Results indicated a decrease in flood duration and frequency, and a decrease in annual flood frequency variation at a site 6.4 km below the dam. Pre‐dam versus post‐dam differences in flood frequency and duration at the site 32.2 km below the dam were related to climate rather than dam effects. Although dam impacts are a concern, this research shows that distance downstream from the dam and downstream tributary and watershed characteristics should be considered before assuming that the dam has changed hydrologic parameters for portions of rivers. This research also indicates that areas of the lower Kaskaskia River may still maintain hydrologic ecological integrity, and could be targeted for restoration and adaptive management purposes. Hydrologic modelling combined with river gage and on‐site well measurement techniques presented in this study could provide detailed flood frequency and duration information for land use, sociological and geomorphological questions in focus areas within river floodplains. Copyright © 2008 John Wiley & Sons, Ltd.     

浅谈优化Vray渲染在制作三维场景的应用研究

用Vray三维渲染引擎来渲染三维场景,其质量和速度是由一些影响因素和参数设置决定的,不同的参数和因素,可以得出不同的三维渲染效果.因此,分析、优化三维渲染质量和速度的影响因素,正确、合理的选择参数对提高Vray最后渲染阶段的质量和速度非常重要.     

固结、渗流和沉积控制方程研究

本文从两相流体动力学的守恒方程出发，考虑固相、液相的相对运动，推导了可以考虑场的不均匀性和流体压缩性的统一形式的控制方程，并对方程所基于的物理概念和相互联系进行了必要的分析。通过对方程适当形式的表达，可导出用于大、小变形固结、渗流和沉积的简化方程，显示了在不同领域的三个理论存在一定的统一性。方程推导过程并未对本构关系加以限制，适用范围较广。依据实际问题的要求，作了不同形式的简化。     

四川省及重庆市中型水电站效益分析

该文分析了四川省及重庆市几座中型水电站的调查材料表明：四川省及重庆市中型水电站不仅在川渝主网和地方电网中起着很大的作用，并具有巨大的社会效益，同时还有综合利用效益，说明修建中型水电站的优越性．     

掺MgO混凝土的宏细观试验研究

利用MgO膨胀剂的延迟微膨胀效应能显著提高大体积混凝土的力学性能,产生的预压应力还能有效提高大体积混凝土抵抗温度开裂的能力,但目前对其微观机理研究不多。采用宏观与微观相结合的方式,研究了不同活性指数、不同掺量的MgO混凝土的力学性能,利用SEM/EDS微观分析手段揭示了MgO对混凝土性能影响的作用机理。试验结果表明:MgO取代部分水泥掺入混凝土中,混凝土的力学性能降低;掺量为4%～5%时,活性指数为100s的MgO混凝土的膨胀率大于活性指数为50 s的MgO混凝土;MgO混凝土的膨胀特性与Ca,Si,Mg,Al等元素的分布情况有关,掺入的MgO将改变界面区Ca,Si,Mg元素的富集特性,Ca元素和Mg元素更易于在界面区富集,导致混凝土宏观力学性能的降低。     

Statistical tools for thermal regime characterization at segment river scale: Case study of the Ste‐Marguerite River

Suitable thermal fish habitats are constrained by both maximum and minimum temperature tolerances. A multivariate and geostatistical approach was developed to estimate stream thermal characteristics at the river segment scale. Data from 22 temperature‐monitoring stations during summer 2007 were used to estimate monthly maximum temperature as well as thermal characteristics such as the number of events, the cumulative degree–days and the associated duration over specific temperature thresholds of 19 and 21°C. The probability of exceeding these temperature thresholds has also been interpolated. The methodology relies on the construction of a multivariate space using physiographic and hydrological characteristics of gauging stations as inputs in a canonical correlation analysis (CCA). A geostatistical interpolation technique, ordinary kriging, was subsequently used to perform interpolation in the physiographical space constructed using CCA. Results from this study were obtained for thermal characteristics estimated into two different interpolation spaces: (1) a 7 metrics space, and (2) an 8 metrics space. Cross‐validation technique has been performed and satisfactory results were obtained. Kriging thermal characteristics (magnitude and duration) into the 7 metric space for a 19°C threshold exceedance leads to best results with Relative Root Mean Square Error (RRMSE) ranging between 9.66 and 15.08%. The study shows that kriging in a multivariate space is a promising tool for water resources managers, especially in cases where risk mapping for lethal or sub‐lethal temperature thresholds may be required for a specific fish species. Copyright © 2010 John Wiley & Sons, Ltd.     

基于MIDAS软件探讨施工工序对深基坑稳定性的影响

基于武汉地铁名都站深基坑工程与水文地质勘察资料,建立了三维工程地质仿真计算模型。依据名都站深基坑开挖支护方案,利用有限元软件MIDAS的摩尔-库仑本构模型,对武汉地铁名都站深基坑施工过程中,不同施工工序下每步开挖之后,基坑的变形情况做仿真模拟计算,并对比分析其对基坑稳定性的影响。结果表明:基坑围护结构的变形情况与施工工序有很大的关系,施工工序越合理,上部土体变形越小,反之越大。因此,在基坑工程的施工过程中,要注重施工步骤的划分与合理安排,从而保证基坑工程的安全。研究成果为以后武汉地区基坑工程的施工设计提供了值得借鉴的经验。