微观建模在城市给水管网系统中的实践

给水管网系统动态建模是自来水公司实现科学管理、提高效益、提高服务水平的重要手段。以天津市给水管网系统建模为例 ,详细地阐述了给水管网系统微观建模的理论与方法。     

微观建模在城市给水管网系统中的实践

给水管网系统动态建模是自来水公司实现科学管理、提高效益、提高服务水平的重要手段.以天津市给水管网系统建模为例,详细地阐述了给水管网系统微观建模的理论与方法.     

用节点水龄量度给水管网的水质状况

通过给水管网的水质模型推导得出了节点水龄的计算公式 ,给出了以节点水龄量度的给水管网水质状况曲线 ,并以此为基础 ,针对某大城市给水管网进行了节点水龄实例计算 ,绘制出整个给水管网等水龄线及节点 2 4h水龄变化曲线图 ,从而得出该城市给水管网基于节点水龄的水质状况。管网节点水龄的计算对从理论上分析给水管网的水质以及对提高给水系统的服务水平均具有重要意义。     

给水管网的分形特征研究

在研究给水管网分形维数的基础上,结合我国不同地区的给水管网分析了给水管网的分形规律.从功能、结构和自相似性三方面,同自然界中广泛存在的具有分形特征的物质流输送系统进行比较,阐述了给水管网的分形特征.并基于盒计数法提出了给水管网分形维数的计算方法,计算了实例管网的分形维数.计算结果表明给水管网是分形体,具有分形特征.同时,分析了影响给水管网分形维数的因素并构建了给水管网分形维数的计算方程.     

深圳市给水管网水质安全管理技术研究

分别研究了出厂水水质稳定性、管网单向冲洗、管网改造模式以及管网水质在线监测系统等技术.提出了适合深圳地区的水质稳定性参数.采用管网单向冲洗后,浊度和细菌总数明显降低,管网水质得到了有效的改善.在小区管网改造方面,将生活给水系统和消防给水系统合理分离,既可以降低消防给水系统对生活给水系统水质污染的风险,又可节省管网改造投资.建设并充分利用管网水质在线监测系统是保障饮用水安全的重要措施.     

基于EPANET本地化的给水管网教学软件开发

水力与水质模拟软件的应用已成为大型给水管网分析的主要手段,高等院校专业课程教学中必须适应给水管网技术发展的需求.为缩短给水管网教学软件的开发周期、节约资源投入,在英文软件EPANET基础上,实现了软件本地化(命名为EPANETH).开发内容包括计算器模块、图形用户界面、帮助文件和用户手册的处理,并形成安装程序,在使用中不断完善.该软件能使学生更深入地理解管网设计理论,提高给水管网系统课程的教学质量.     

母管制给水泵组的优化运行研究

采用Apros5．04高级过程仿真支撑系统,以某热电厂给水管网系统为对象,通过系统提供的图形组态建模,自动化仿真计算,开发出给水管网模型。分析模型计算出的参数,掌握给水系统运行特性,得出不同给水泵组合方式下的电耗以及对高压加热器给水流量分配的影响,进而优化出给水系统的经济运行方式。该项目的实现将大大提高全厂给水系统的运行水平与设备监控水平,完善经济指标考核与分析,对提高全厂机组运行的安全性、经济性具有重要意义。     

港区给水工程管网模拟软件的选择

随着港口经济的高速发展,大规模、综合性的港区工程对给水管网的规划和设计提出了更高更精确合理的要求,而传统的给水管网系统的设计和监控方法逐见弊端.因此,兼具水力计算和系统分析等功能的管网模拟软件逐渐成为管网系统设计和管理的重要手段。文中介绍了对目前世界上市政工程中应用较广的给水管网软件,并比较分析了其优缺点,希望能在港区工程给水管网建设、管理以及模拟软件开发方面提供参考。     

城市给水管网物理仿真模型研究

随着城市规模的不断扩大和给水管网改扩建范围的延伸,给水管网系统管理越来越复杂,管网系统运行风险也越来越高。为了保证供水系统的安全运行,建立与原给水管网等效的物理仿真模型,对于分析实际管网的运行工况和预测判断实际管网的风险,减少因管网事故带来的损失有着重要的现实意义。结合渭南市临渭区给水管网,运用管网简化理论对复杂的城市给水管网进行简化,以压力分布为约束限制,由管网理论计算与实际管网运行数据的对比结果,验证了该简化方法可较好地反映原管网的压力分布情况和整个管网的运行状态。     

给水管网可靠性计算方法

近年来随着计算机技术的不断发展,应用计算机技术解决给水管网的优化问题成为了研究的热点。然而由于考虑管网优化问题时,目标函数往往只考虑管网的运行或者投资的费用最小,没有考虑给水管网的可靠性指标,脱离了实际情况,导致难于得到真正的应用。对管网可靠性进行研究,并寻找有效且适用可靠性计算方法成为了目前需要解决的问题。一、给水系统可靠性的定义给水系统的可靠性是指在一定时间内,在一定的运行条件下给水系统完成预定功能的性质。给水系统的功能是     

地下厂房施工过程的三维非线性数值模拟分析

根据冗各电站地下厂房开挖支护的施工顺序,以隐式杆单元模拟锚杆,以壳单元模拟混凝土喷层,采用三维非线性有限元技术,对洞室群的开挖支护动态过程进行了模拟计算。通过三维非线性有限元计算分析得到:洞室群动态开挖过程中围岩应力变形的分布规律,围岩塑性区的发展规律,锚杆受力变化情况。计算结果表明:整个开挖过程中,洞周围岩位移变化规律正常,量值较小,塑性区主要分布在洞室周边,围岩稳定性较好;但在洞室交叉口处围岩的变形较大,出现较大范围的塑性区,在此基础上提出了支护措施优化方案,并对优化方案的效果进行了评价。     

Evaluation of freshwater mussel relocation as a conservation and management strategy

The relocation of unionacean mussels is commonly used as a conservation and management tool in large rivers and streams. Relocation has been used to recolonize areas where mussel populations have been eliminated by prior pollution events, to remove mussels from construction zones and to re-establish populations of endangered species. More recently, relocation has been used to protect native freshwater mussels from colonization by the exotic zebra mussel Dreissena polymorpha. We conducted a literature review of mussel relocations and evaluated their relative success as a conservation and management strategy. We found that 43% of all relocations were conducted because of construction projects that were forced to comply with the Endangered Species Act 1973 and that only 16% were monitored for five or more consecutive years. Most (43%) relocation projects were conducted from July to September, presumably a period when reproductive stress is relatively low for most species and the metabolic rate is sufficient for reburrowing in the substrate. The mortality of relocated mussels was unreported in 27% of projects; reported mortality varied widely among projects and species and was difficult to assess. The mean mortality of relocated mussels was 49% based on an average recovery rate of 43%. There is little guidance on the methods for relocation or for monitoring the subsequent long-term status of relocated mussels. Based on this evaluation, research is needed to develop criteria for selecting a suitable relocation site and to establish appropriate methods and guidelines for conducting relocation projects.     

基于模型试验的河床砂砾石层基本特性研究

为了经济可靠地确定深厚覆盖层的基本特性参数,以大渡河双江口水电站坝基河床砂砾石层基本特性研究为工程背景,进行大尺寸模型试验,研究河床砂砾石层的旁压模量和动探击数随密度、级配以及上覆压力的变化规律。根据室内模型试验结果,结合现场旁压试验及钻孔试验成果,推断出坝址区河床砂砾石相关层位的密度,并依此进行砂砾石室内力学试验,获得设计所需力学参数。研究成果可为深厚覆盖层基本特性测试提供新的方法。     

基于BP神经网络-马尔科夫链模型的隧道围岩位移预测

在隧道工程施工中,围岩位移预测起着很重要的作用。将BP神经网络-马尔科夫链模型引入到隧道围岩位移预测中来,通过对训练样本的学习,利用BP神经网络实现了对位移时间序列的滚动预测,同时得到了实测值与预测值的相对误差;在此基础上利用马尔科夫链对相对误差进行修正,有效地提高了预测结果的精度。并将该模型应用于某公路隧道拱顶下沉位移时序预测中,结果表明该模型具有精度高、科学可靠的特点,为隧道围岩变形的预测提供了新的途径。     

Short communication. Pipelines as a refuge for freshwater snails

In the lower River Murray, Australia, populations of gastropods have declined markedly over the past 40 years. Of the native fauna of about 18 species, only the ancylid Ferrissia petterdi remains common (but in patches), and another five species feature in sporadic local resurgences. Until recently the viviparid Notopala was thought to be extinct. The introduced physid Physa acuta is widespread, but in low numbers. The decline probably is associated with flow regulation, high turbidity and the introduction of common carp. Snail populations have persisted, however, in irrigation pipelines fed from the river, where they periodically cause blockages. This paper reports the discovery of the only known populaion of Notopala hanleyi in a pipeline where the inner wall accumulates microbial and other organic matter, providing high quality food for snails. In the Murray before regulation most of the periphytic biomass was probably microbial, as fluctuating water levels would have maintained littoral communities in a highly productive, early state of succession his postulated that, by stabilizing seasonal water levels, regulation has promoted the production of filamentous green algae, an inferior food source, and so displaced snail populations from the open aquatic environment.     

浙江省水域调查录入系统的设计和应用

浙江省水域调查录入系统将调查数据与电子地图相整合,对分类水域数据进行统计计算,并对输入数据进行合理性和完整性检查,得到调查范围内现有水域的详细数据,实现了水域调查数据输入、计算、统计和查询的数字化管理,提高了工作效率和工作质量,为各地下阶段水域保护规划编制和水域管理工作提供了数据支持。对该系统的设计原则、功能和技术设计等作了介绍。     

Automated system for removal and pneumatic transport of fly ash from electric precipitator hoppers

A system for removal and pneumatic transport of fly ash is examined, in which air pulses act on batches (pistons) of ash formed in a duct. Studies are made of the effect of several physical parameters on the force required to displace a piston of ash and these serve as a basis for choosing a system for removal and pneumatic transport of ash simultaneously from several hoppers of an electric precipitator. This makes it possible to separate the ash particles according to size without introducing additional components. Formulas are given for calculating the structural and dynamic parameters of this system and measurements of indirect dynamic parameters are used to calculate the input-output characteristics of the system. In order to optimize the system, configurations for summing several ducts into a single transport duct for pneumatic ash transport are proposed. Some variants of dry ash utilization and the advantages of producing of size-separated particles are considered. __________ Translated from élektricheskie Stantsii, No. 2, pp. 26–30 (2008).     

The flood pulse advantage and the restoration of river-floodplain systems

The ‘flood pulse advantage’ is the amount by which fish yield per unit mean water area is increased by a natural, predictable flood pulse. Evidence for this increase is presented from tropical and temperate fisheries. It is argued that increasing multispecies fish yield by restoring the natural hydrological regime is consistent with increasing production of other trophic levels and with restoration from ecological and aesthetic viewpoints. When applied to a river-floodplain system, this restoration would provide a large, self-sustaining potential for recreation, commercial exploitation, and flood control. An interim ‘natural flood pulse’ restoration approach is proposed for systems modified for navigation. This approach approximates the natural hydrological regime in a river reach and is intended as a first step in the long process of restoring the watershed.     

基于CT-连续加荷水泥乳化沥青混凝土细观损伤规律研究

利用CT技术对水泥乳化沥青混凝土的细观损伤过程进行实时扫描观测,获得了混凝土试件在连续加荷下的CT图像。通过采用直观分析法、CT数分析法、CT数与损伤变量关系3种方法分析表明,水泥乳化沥青混凝土的破坏过程可分为压密、扩容、裂纹扩展、破坏4个阶段,同时混凝土在受压过程中具有韧性,在极限荷载之前各断面处于压密和微扩容的强化阶段,极限荷载之后混凝土从损伤到破坏发展比较平稳。     

浅谈天湖水电站水轮机运行故障及处理措施

简述天湖水电站投运以来各种故障的表现形式，分析其原因，提出了相应的处理方法及措施，并对合理利用国内外设备提出建议。