区域夜间最小流量的灰色DGM(1,1)动态预测

针对一个实际独立计量区域(DMA),根据数据采集与监控系统(SCADA)的数据,采用趋势图和灰色关联度分析了DMA入水口的流量特征。然后基于灰色理论建立4个夜间最小流量的灰色模型,对比分析4个模型的模拟和预测精度,确定离散灰色DGM(1,1)模型是此DMA的夜间最小流量的最佳预测模型。灰色DGM(1,1)新陈代谢模型具有很好的动态预测精度,应用灰色DGM(1,1)新陈代谢区间预测方法分析了此DMA区域的夜间最小流量的阈值,从而为DMA的漏失状况起到预警作用。     

不同地区DMA流量特征分析与漏失评估

供水管网漏失是城镇供水管理面临的重要挑战。基于管网独立计量区(DMA)的流量特征来评估管网漏失是目前常用的技术,但不同地区管网的运行状况与用户用水模式不同,漏失评估技术参数的设置也应有所不同。因此,分析不同地区DMA的流量特征对漏失评估具有重要的意义。以我国华北、华东、华南、西北四个地区共计91个DMA为研究对象,分析了流量时变化、流量月变化、最小夜间流量(MNF)出现时间等流量特征,发现各地区DMA流量特征呈现出不同的规律;采用MNF与日均流量(F)比值(MNF/F)、单位户数与单位管长MNF分布等方法评估了DMA漏失情况,认为综合考虑这三个指标可对DMA的漏失状况做出更客观的评价。     

DMA不可避免漏失量计算值与实测值对比分析

构建独立计量区域（DM A ）是一种经济有效的控制供水管网漏损的方法,近年来受到国内外供水企业的广泛关注。利用IWA提出的不可避免漏失水量计算公式计算独立计量区域中不可避免漏失水量,与采用最小夜间流量法实测出的该DM A不可避免漏失水量进行对比分析。并利用SPSS软件对不可避免漏失水量经验公式影响因素进行验证,可为进一步提出适合我国独立计量区域不可避免漏失量计算方法提供依据。     

生活给水及热水供应设计秒流量计算方法的研究(二)

对我国现行生活给水及热水供应设计秒流量的计算方法与国外概率法进行比较分析 ,得到概率法能够比我国现行方法更客观计算设计秒流量的结论。分析了不同概率法之间的异同。对我国建立设计秒流量概率计算法应做的工作提出了建议     

生活给水及热水供应设计秒流量计算方法的研究(一)

指出并分析了我国现行生活给水及热水供应设计秒流量计算公式存在的缺陷和不足。深入研究了国外建立在概率理论基础上的各种设计秒流量计算方法。对俄罗斯设计秒流量计算方法的发展过程进行了研究     

伸顶通气管道系统中瞬间流排水特性的影响因素研究(三)瞬间流量在伸顶通气排水系统中流量与压力的关系探讨

为了探讨排水管道中压力与流量间的关系,使用了新型瞬间流量测量装置间接测量瞬时排水到达各层横支管位置时的流量,并通过压力传感器测定各层横支管的压力。通过分析,排水层下面各层的最大负压值与最大流量并非同步出现,流量的衰减速度与负压的衰减速度也不一致。     

基于SCADA系统给水管网实时检测爆管位置方法的研究

提出了基于SCADA系统城市给水管网实时检测爆管位置的实用方法,通过对管网测压点进行优化布置,利用SCADA系统监测到的管网爆管前后监测点的信息,对管网进行正常和爆管状态下的状态估计,根据整个管网爆管前后节点水压的变化,考虑各节点在管网中的权重,对监测点赋予较大的权重,用模糊相似优先比法快速准确地寻找爆管管段.通过对一城市概化管网的运算验证表明,漏失量在20 L/s以上时,可以达到96%以上的准确率,漏失量为5 L/s的检测准确率也在80%以上.对于DN250的管段,可检测的最小爆管出流量为5 L/s;对于DN900的管段,可检测的最小爆管出流量为40 L/s(＜40 L/s时可检测出漏水区域).     

An Integrated Model to Evaluate Losses in Water Distribution Systems

To evaluate non revenue water (NRW) and losses in water distribution networks a methodology is developed by applying “annual water balance” and “minimum night flow” analyses. In this approach the main NRW components such as leakage from reported and un-reported bursts and background leakage, with real or estimated data, enabling assessment of indices of leakage performance are evaluated. Also, a novel procedure is introduced in this paper that can determine the nodal and pipe leakage by using a hydraulic simulation model. Recognising the pressure dependency of leakage the total consumption is divided into two parts, one pressure dependent and the other independent of local pressure, and the hydraulic behaviour of the network is analyzed. A computer code is developed to evaluate all components of water losses based on the proposed methodology. For better representation of the results and management of the system, the outputs are exported to a GIS model. Using the capabilities of this GIS model, the network map and attribute data are linked and factors affecting network leakage are identified. In addition, the effects of pressure reduction are investigated. The model is illustrated by a real case study. The results show that the suggested model has overcome the shortcomings of the existing methodologies by accounting for the leakage and other NRW components in water distribution networks more realistically.     

A Stochastic Non-linear Programming Model for a Multi-period Water Resource Allocation with Multiple Objectives

A rapid increase in demand and severe droughts in recent years has increased the pressure on water supplies throughout most parts of Australia. This has resulted in the need for tools to allocate limited water across users in different regions, and explore scenarios so as to achieve economic, social and environmental benefits. A major challenge in water resource allocation is dealing with the uncertainty in the system, particularly with respect to reservoir inflow. Stochastic non-linear programming is applied to water resource allocation to accommodate this uncertainty across the time periods of the planning horizon. A large range of solutions is produced representing the distributions of uncertainty in reservoir inflow. These solutions are used in a Monte Carlo simulation to estimate the trade-off in amounts of water allocated versus risk of not achieving minimal reservoir levels. The methodology is applied to a case study in South East Queensland in Australia, a region which is currently facing a severe water shortage over the next 3 years. A new water supply initiative that the Queensland State Government is considering to overcome the water crisis is assessed using the methodology.     

全日制村镇供水管网经济流速的计算

村镇供水管网设计是一项系统工程,选择合理的经济流速对于降低管网的总费用与运行费用是非常必要的。考虑资金的时间价值,结合山东省某村镇的农村供水工程实例,得出了适合该村镇供水管网设计的经济流速。该方法可为全日制村镇供水工程设计提供参考。     

供水系统中经济流速与管径优化节能工程试验研究

针对现有供水系统设计缺陷,研究了基于经济流速的管径优化法,提出了供水系统运行费用、设备费用、管道敷设费用和泵房建设费用及总费用的时间价值.根据使总费用达到最小值的原则,给出了经济流速和管径优化的计算示例和简要说明,并分析了舍维列夫公式和海曾-威廉公式用于镀锌钢管沿程水头损失计算的适用性.     

Identifying Pipes and Valves of High Importance for Efficient Operation and Maintenance of Water Distribution Systems

Failure of a pipe or valve in a water distribution system causes service disruption and other inconveniences to the customers at or downstream of the failure location. To minimize the impact of such a pipe or valve failure, it is crucial to identify those pipes or valves whose failure will have the most severe consequences in degrading the performance of the system relative to that of other pipes or valves. In this paper, we develop two failure analysis methodologies, Pipe-by-Pipe and Valve-by-Valve, to prioritize the importance of pipes and valves in a water distribution system. The relative importance of individual pipes and valves is evaluated according to the number of customers who are forced out of service as a consequence of a pipe or valve failure. The methodologies are based on a segment-finding algorithm which defines a series of isolated pipes in the case of pipe or valve failure. A procedure based on the Breadth First Search is also developed to find sections of pipes that are unintentionally isolated in the isolation procedure for failed pipes. The number of unintentionally isolated customers is included in the Pipe-by-Pipe and Valve-by-Valve analyses in order to incorporate this negative effect of unintended isolation of pipes. The methodologies are applied to a case study of a water distribution system for which the most important pipe and valve are identified. The results are analyzed to form a guideline for improving the system reliability. The proposed methodologies were found to be a valuable tool for ensuring efficient operation and developing appropriate maintenance strategies, and thereby for improving the reliability of many water distribution systems.     

Environmental Integration of Small Hydropower Development

On the basis of cooperative research with European professionals, problems relating to environmental and ecological protection were discussed while small hydropower development in China currently was introduced in this paper. Guidelines of small hydropower development dealing with environmental protection were sug- gested hereby. Various specific technical environmental solutions focusing on small hydropower development applied in European and other developed countries were also introduced in this paper. Main environmental solutions are discussed as follows： integrated design should be advocated during plan/design stage,＂ ecohydraulic engineering and its utilization in SHP design and construction; effective technical approaches to relieve and eliminate the impact of river interception and fix the reasonable minimum biological flow; environment-friendly mitigation and compensation measures for high/low-head hydropower schemes applied in diversion works, intake, nature-like fish-passes, penstock and powerhouse design; study and application of the new technology, material and equipments; launching renovation of environmental protection in existing stations; emphasiz- ing public participation and their acceptability for the SHP environment; coordinated inter-disciplinary study at national level, etc. Two case studies in Sweden and Australia are given here.     

基于瞬变流动分析的给水管网事件模型

基于流体瞬变流动理论模型,对管网节点、水泵等边界条件的水力特性及模型方程的特征线解法进行了论述和分析;基于面向对象的分析和设计原理,对给水管网事件模型的框架架构进行了论述,应用给水管网事件模型对实例管网事件进行模拟演算并对结果进行分析。