解极近水面飞行时全机气动力中水波效应的边界元法

本文以边界元法为基础，在线性水波的假定下，对贴近水面飞行的三维飞行器，提出了一种计算气动力中水波效应的方法。本文共分三部分：I．分析了用边界元法计算非定常压力分布的困难和产生这一困难的原因，指出了对非定常问题，强度分布函数解必须保证唯一性而不能差一个随时间变化的常数。为此对无穷远条件必须有一个正确提法，并在此基础上给出了克服这一困难的方法。Ⅱ．水波效应问题的数学提法，包括各种定解条件和解的最后边界积分形式，导出了在飞行器形成的压力场的作用下波高应满足的微分积分方程，给出了求解的基本方法和步骤。Ⅲ．对于一个包含有复杂外形的机身、机翼、端板、垂尾和平尾的三维机型在贴近水面飞行时，作了包括水波效应在内的全机气动力计算，给出了水波效应随攻角、飞行高度、波幅、波长及波的入射方向等的变化，得到了有意义的结果，同时也证明了本文提出的计算非定常涡强分布函数的方法是正确的。     

挡土结构中土体被动临界滑动场及被动土压力的数值计算

本文将边坡临界滑动场方法进行推广和改进，计算挡土结构中土体被动临界滑动场PCSF和被动土压力。首先建立土体极限平衡方程并引入条间力函数，给出平衡方程求解格式；介绍改进的土体临界滑动场数值模拟技术；最后给出实用的被动土压力计算图。本文方法原理简单、精度高，可应用于工程计算。     

随机脉动水压力作用下的结构响应

本文从分析相关系数与相干函数的相似性出发，讨论了结构对连续分布的脉动压力作用的随机响应，给出了相干函数表达的结构响应，并定义了新的时空相关尺度－相干尺度，这个尺度实际上是每个频率分量随机荷重的平均作用空间，最后给出实例对比了试验与计算结果，说明提出了方法是正确的。     

三维频域有航速格林函数的数值计算与分析

Havelock型三维移动脉动源格林函数的计算是面元法求解航行船舶在波浪中的运动问题的关键.该文基于单重积分形式的移动脉动源格林函数,采用LOBATTO法以消除积分区间端点处的奇异性,采用多项式法快速准确计算复指数积分,在格林函数的偏导数积分计算中对复指数积分项进行了分部积分处理,解决了格林函数在π/2处被积函数趋于无穷且出现高频振荡所导致的积分困难.数值计算和比较表明:该方法可以准确计算出不同航速和脉动频率下任意位置的格林函数及其偏导数,能准确给出不同速度下三维移动脉动源的波形,适合用于有航速浮体的频域水动力计算中.     

三维振荡水柱波能转换装置的流体动力计算

文章对三维有侧向开口的波能转换固定式箱体;受波浪扰动时,用三维GREEN函数法计算箱体内振荡水柱的流体动力特性。在计算中使内场的响应脉动源与外场的扰动脉动源,两者在交界面上相互匹配,以满足压力与速度连续条件。计算在HP-1000型机进行,结果和模型试验比较,相当一致。     

弧形闸门流激振动的物模-数模预报

介绍了弧形闸门流激振动的物模一数模预报方法，即用重力相似的水力模型测定与有限元计算相应的各面板单元上的脉动压力，再用有限元动力计算确定结构响应；应用复变函数理论确定了弧门径向运动时的水体附加质量分布，给出了相应的经验表达式；用物模一数模方法预报了作用在石佛寺水库弧形闸门上的面脉动压力及弧门振动特性。     

数值计算域内产生波浪的方法

解决入射边界域内反射波浪吸收问题的方法之一是在域内产生所需的波浪，而在边界处采用其它方法来吸收域内反射波浪，本文采用源函数的方法。给出了Bossinesq方程计算域内产生波浪的方法，典型波浪的数值模拟计算结果表明，该方法可以在域内生产所期望的波浪。     

浅水波-流对直立桩柱作用的分层数值解法

本文采用分层方式，用水气比拟方程计算由于存在桥墩等障碍物而造成的浅水波高度的变化，以此给出水下粘性层内计算域上表面的压力，用传统的N-S方程计算粘性层内的流动，得到了波一流联合作用下桥墩上的压力分布和河床上压力与剪应力分布随时间周期性的变化过程，并得到了一些有意义的结论。     

任意形状复合油藏压力动态的边界元分析

油气藏形状对井底压力动态响应有着显著的影响，常规的解析方法只能计算规则形状油气藏的井底压力响应。该文建立了任意形状复合油藏不稳定渗流的数学模型，并将区域分割法与边界元方法相结合，研究了任意形状复合油藏不稳定压力响应的计算方法，应用杜哈美原理考虑了表皮效应与井储系数对井底压力动态响应的影响。绘制并分析了复合油藏的典型曲线，通过分析指出油藏的边界性质会影响典型曲线后期形态，而内区形状的也可能掩盖复合油藏典型曲线的特点。     

三峡原型水轮机的非定常湍流计算和压力脉动分析

本文对三峡原型混流式水轮机进行了三维非定常湍流计算，得到水轮机的非定常流场，预测了尾水管内、转轮前、活动导叶前、固定导叶前和蜗壳进口的压力脉动。通过与模型试验预测结果的比较看出，计算能够准确预测水轮机内的压力脉动。分析表明尾水管内涡带和转轮与活动导叶间的动静干扰是产生压力脉动的两个主要脉动源，并在整个水轮机流道内传播。     

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.     

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．     

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.     

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.     

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。     

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。