变速抽水蓄能机组的运维成本分析

以定速机组运维成本的分析为基础,对比变速机组与定速机组的结构差异,结合世界上变速机组的实际运行数据,分析了变速机组的运维成本。结果显示变速机组的运维成本与定速机组基本一致,但变速机组的运行时间较定速机组增加了20%以上。     

丹江口大坝加高对机组运行的影响及改造方案研究

丹江口电站首台机组于1968年10月投产发电,经过数十年的运行,机组设备老化,部分机组已陆续改造。南水北调中线工程实施丹江口大坝加高后,正常蓄水位由目前的157 m提高到170 m,对机组运行产生一定影响。本文简要介绍了机组运行现状,从机组强度、能量特性、空蚀特性、稳定性等方面详细分析了对机组运行的影响,并提出了机组改造的具体方案。     

基于振动特性试验的大型混流式机组稳定性分析与评估

针对五强溪水电厂机组运行过程中振动摆度过大等设备问题,设计了混流式水电机组振动特性试验,以试验结果为依据,对混流式机组运行稳定性进行全面分析与评估。通过机组高、中、低多水头段的稳定性试验,分析了机械因素、电气因素、水力因素等振源对机组稳定性的影响;通过机组的大负荷调节试验,研究了调节过程对机组稳定性的影响;通过机组大负荷调节与稳态运行工况对比分析研究、开停机过渡过程分析研究,评价了过渡过程机组稳定性能,并在此基础上,提出了五强溪电厂机组优化运行措施,可保障设备安全稳定运行。     

影响灯泡贯流式机组振动的因素分析

分析了灯泡贯流式机组的基本结构及其支撑特点,论述了引起灯泡贯流式机组振动的主要因素:液体气蚀造成的机组振动、卡门涡列引发机组振动造成的机组振动、导叶和桨叶协联关系参数设计不合理造成的机组振动。     

浅谈界牌电站机组技术改造

介绍了界牌电站机组现状、存在的主要问题、技术改造方案、改造后的机组主要参数,提出了对机组改造的一些认识。通过对电站机组进行整体技术改造,根除了机组运行的安全隐患问题,同时提高了机组的发电效率和电站年均发电量,达到机组技术改造的目的。     

三峡左岸电站ALSTOM机组稳定性分析

根据TN8000机组状态监测系统投运以来所记录的三峡左岸电站10号和12号机组的大量数据,利用TN8000系统提供的专业分析工具,对三峡左岸电站ALSTOM机组的运行稳定性进行了深入分析,明确了机组发生涡带脉动时的不稳定工况区,并指出机组存在特殊压力脉动区,还对10号机组异常事故情况下的数据进行了深入分析并分析了引起异常的原因。分析结论对于掌握ALSTOM机组的运行特性和指导机组运行具有重要的作用。     

兰溪发电公司机组启动流程图的开发及应用

对浙江浙能兰溪发电有限责任公司超临界燃煤机组启动过程中遇到的异常情况进行分析,有针对性地开发了机组启动流程图。介绍了机组启动流程图的构成,利用机组启动流程图来指导、规范机组启动工作,确保启动过程顺利进行。     

基于辅助服务的机组无功优化分配

建立了基于无功辅助服务的机组无功优化分配模型,并与等功率因素无功分配模型进行了比较。以二滩水电站机组为例进行了仿真分析,证明采用基于无功辅助服务的机组无功优化分配模型在满足机组安全、稳定运行的前提下,能够增加机组有偿无功辅助服务电量,提高机组经济运行水平,增加电站经济运行效益。     

湖南镇水电站#5机组减振增容改造

介绍了湖南镇水电站#5机组减振增容技术改造的原因,论述了#5机组减振增容技术改造的实施情况。湖南镇水电站。5机组改造后的试验和运行结果表明,湖南镇水电站#5机组减振增容技术改造非常成功,机组的技术指标达到了增容改造的预期效果。     

S109FA机组惰走分析

介绍了S109FA机组的特点,统计了某S109FA机组惰走曲线及惰走时间。分析了S109FA机组惰走曲线的影响因素,提出了＂统一S109FA机组惰走时间标准＂的建议,为同类型机组处理同类问题提供参考。     

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。