基于延时模拟的供水管网可靠性分析

提出了一种基于延时模拟的供水管网可靠性评估模型.该模型不仅考虑到一天内用户用水量的变化,而且考虑到管网组件故障的随机性,并采用随机模拟的方法对各个节点和供水管网系统的可靠度分别进行计算,能够较为客观、真实地反映供水管网系统的可靠程度.模型的实例应用结果也证明了其实用性和合理性.     

供水管网地震漏损蒙特卡洛模拟分析

为研究供水管网在不同地震烈度下的漏损情况和水力特性,基于管道地震破坏评估模型和概率分析方法,对不同地震烈度下管线的破坏概率和渗漏状态进行了计算分析,引入折减系数对管段抗震可靠度分析方法进行改进,并与传统计算方法比较,验证了其合理性。发展了Monte Carlo模拟技术在供水管网流分析方面的应用,并考虑带渗漏和爆管两种出流方式。编制程序对一大型管网进行了模拟分析,给出了震后带漏损情况下管网的漏失率和破坏情况,结果与实际地震灾害情况相符。     

供水管网漏损评估与控制方法

随着可持续发展、经济高效性以及环境保护理念深入人心,供水管网的漏损问题已成为国际热点。漏损并不仅是水务公司所关注的经济议题,更是一项涉及环境安全与健康的问题。主要探讨了漏损的评估和控制管理,以全面的视角审视漏损技术管理水平,旨在依据低成本的手段获取管网信息,寻求切实可行的方法来改善供水管网的运行状况,提高供水的可靠性。通过对现存漏损评估和控制方法的优劣分析,为未来漏损领域的研究工作提供建议。     

基于动态模拟的城市供水管网风险评估研究

供水管网是城市生命线的重要组成部分,为了更好地服务用户,同时提高对供水管网的管理水平,对已有供水管网进行风险评估必不可少.选取管道埋深、管压、管材、管龄、管径、道路荷载、水龄7个评估指标,构建供水管网风险评估模型,并对上海市MH区供水管网进行风险评估.评估结果表明,由于管道的管龄和管材对于得分的贡献率较高,因此管龄较长...     

地震对城市供水管网的破坏情况分析

详细分析了国内外发生的大地震对城市供水管网的破坏情况，总结了不同管材、管径、接口形式、地基类型等的抗震性能差异，并对如何提高供水管网的抗震性提出了具体建议。     

基于先验信息的供水管网阻力系数识别

供水管网阻力系数识别是指通过调整管网水力模型中管道阻力系数,使模型计算值与监测值相符的过程。由于实际中监测点数量有限,管网阻力系数识别为欠定的优化问题。现行方法通常采用管道分组这一参数化方法将欠定问题转换为超定,应用遗传算法或其它随机搜索算法求解。提出了基于先验信息的供水管网阻力系数识别算法,所提出算法根据管道管材、管龄等先验信息对管道阻力系数进行估计,并将估计值作为伪观测值引入目标函数将欠定优化问题转换为超定,采用高斯-牛顿算法进行求解。与现有方法相比,所提出算法避免了管道分组不唯一的问题;再者,推导了供水管网阻力系数雅克比矩阵解析式用于搜索向量构造,提高了参数识别计算效率。采用小型管网阐明了雅克比矩阵计算及搜索向量构造,利用大型管网验证了算法的实用性。     

城市供水管网漏失的成因及控制方法

根据工作中的实际经验和体会,对城市供水管网漏失状况进行了归纳、分析,并对漏水原因、检漏方法及降低漏失措施提出了一些具体建议。     

基于GIS技术的城市供水管网信息系统

为改善和提高城市供水企业的管理水平,企业改革、改制,适应市场化发展,应用现代GIS技术,研究设计城市供水管网信息系统。本系统中,重点阐述了GIS技术的城市供水管网信息系统的结构。本研究提出采用先进的GIS技术来提高水资源的利用率和供水企业的管理水平,对于供水企业及时、合理、有效的利用现有的水资源,对促进城市建设和经济发展具有普遍的实在的意义。     

山区城市供水管网平差计算方法及应用

根据山区城市高海拔地区向低海拔地区供水的给水管网运行特点，阐述其管网平差的原理及方法。以冀中能源峰峰集团棚户区供水管网工程为例，介绍山区城市高海拔地区向低海拔地区供水的给水管网平差计算的具体过程。设计及应用情况表明．该方法简单实用，设计结果满足实际工程需要。     

基于Matlab的供水管网余氯衰减模拟

建立了基于拉格朗日时间驱动法的供水管网余氯衰减微观模型,使用具有科学计算和绘图功能的Matlab软件和Access数据库建立了供水管网余氯衰减动态模拟系统.该模拟系统不仅可以对不同工况、不同时刻供水管网的余氯衰减进行动态模拟,而且还可以动态绘制管网余氯等值线图和等值面图.经算例验证,该模拟系统可准确地进行管网余氯衰减动态模拟,通过分析模拟结果和系统绘制的动态余氯等值图可以全面反映不同时刻供水管网所有节点的余氯衰减状况.     

城市供水系统抗震防灾规划研究

基于传统理论,结合城市防灾规划的思想研究城市的供水系统防灾规划措施,对城市大震后用水量的估算进行了分析,就如何确定城市供水系统防灾管网作了探讨,提出了加固整修供水设施和制订应急方案应遵循的三个原则,以确保震后做好应急供水工作。     

Seismic functional reliability analysis of water distribution networks

Due to the huge destructive power of strong earthquakes, many breaks appear on water pipelines after such events. As a result, water leaks from these breaks, causing function loss of water distribution networks (WDNs). In order to evaluate the seismic performance of WDNs, these leaks cannot be ignored. In this paper, by adding a leakage model to the hydraulic equation of WDNs in a daily operation state, a new hydraulic equation is established to describe WDNs after the occurrence of earthquakes. As it is a stochastic equation, a random perturbation method is used to solve the equation and give the mean, standard deviation and skewness of the nodal head. In the meantime, a performance function is established to evaluate the reliability of WDNs. Three reliability analysis methods, a mean first-order second-moment method and two third-moment methods, are used to give the seismic functional reliability of WDNs. Meanwhile, two networks, a small WDN and an actual WDN which suffered serious damages during the Wenchuan Earthquake, 2008, are studied to compare the efficiency and precision of the three reliability methods.     

城市供水调度事件系统的研究与开发

在实际供水系统中,调度决策系统除常规运行调度以外,还存在事故应急等处理决策。笔者通过建立调度决策事件系统,从日常事件、计划事件和突发事件三类来进行研究,根据发生事件的不同来源和性质,采取不同的对策。同时,在全面分析调度事件系统组成的基础上,对调度事件系统软件进行了开发。     

Stochastic seismic collapse and reliability assessment of high‐rise reinforced concrete structures

To provide knowledge beyond the conventional engineering insights, attention in this work is focused on a comprehensive framework for the stochastic seismic collapse analysis and reliability assessment of large complex reinforced concrete (RC) structures. Three key notions are emphasized: the refined finite element modeling and analysis approach towards structural collapse, a physical random ground motion model, and an energy‐based structural collapse criterion. First, the softening of concrete material, which substantially contributes to the collapse of RC structures, is modeled by the stochastic damage constitutive model. Second, the physical random ground motion model is introduced to quantitatively describe the stochastic properties of the earthquake ground motions. And then the collapse‐resistance performance of a certain RC structure can be systematically evaluated on the basis of the probability density evolution method combining with the proposed structural collapse criterion. Numerical results regarding a prototype RC frame‐shear wall structure indicate that the randomness from ground motions dramatically affects the collapse behaviors of the structure and even leads to entirely different collapse modes. The proposed methodology is applicable in better understanding of the anti‐collapse design and collapse prediction of large complex RC buildings.     

给水系统可靠性的确定方法与发展

简要介绍了给水系统中管网和水厂两部分研究者所使用的传统确定系统可靠性的方法和最新发展，并对各种方法进行了简单的比较，同时概要介绍了管网可靠度问题在模型中的实现。     

供水系统运行状态实时模拟方法

建立了供水系统运行状态实时模拟模型,在已知给水管网拓扑结构的基础上,利用实测的系统总供水量和少量管网测压点数据,实时模拟管网所有节点水压.利用Rosen投影梯度法求解模拟模型,对某供水系统的模拟计算表明,该模型计算精度较高,速度较快,能满足供水系统实时模拟的需要.     

On the significance of maximum number of components failures in reliability analysis of water distribution systems

Many factors may influence the results of a reliability analysis for a water distribution system (WDS). These may include (but not limited to) the techniques chosen for reliability assessment, criterion to measure a system's reliability, number of components-failure combinations and failure probabilities and/or frequencies. Among these factors, the maximum number of components-failure scenarios is an important one which has not received sufficient attention in the literature. This study estimated the accuracy in reliability and damage tolerance analysis when an unrealistic and imprecise number of failure scenarios is assumed. Exercising a hypothetical WDS, the modified version of EPANET2 was applied for the hydraulic analysis. The reliability and redundancy or damage tolerance were evaluated based on weighted mean of performance indices of the system. The results indicated that incorporation of maximum acceptable error allow the engineers to estimate the number of failure combinations and ultimately to conduct a more computationally-efficient and realistic reliability assessment. Application of this methodology prevents redundant and unnecessary hydraulic simulations in reliability analysis and reduces computational simulations significantly.     

A resilience assessment method for urban water systems

Infrastructure planning for Urban Water Systems (UWSs) is challenged by, inter alia, increasing uncertainty in both demand and availability of water and aging infrastructure, and this is already impacting the climate-proofing of cities. In this context, the idea of resilience has been gradually embraced by the water sector, but the term itself is not yet universally defined, nor operationalised. Here, we propose a methodology to assess the resilience of a UWS, defining it as the degree to which the UWS continues to perform under increasing stress. A resilience assessment method is then proposed as a ‘stress-test’ of UWS configurations, under increasingly more stressful scenarios. We then demonstrate a toolbox assembled for the proposed analysis using, as a proof of concept, a semi-synthetic case study. Results are promising, suggesting that the approach could assist in the uptake and evolution of resilience thinking in strategic water infrastructure decision making, leading to water-wiser cities.     

An assessment of high-order bounds for structural reliability

Second-order bounds are often used to estimate the reliability of series structural systems. However, the quality of second-order bounds is poor when the failure modes are highly correlated. This paper examines the merit of third and higher-order bounds. First, the general form of the nth-order upper and lower bounds is derived. Second, an efficient algorithm for computing the n-dimensional multinormal integral is presented. Finally, the performance of the third and fourth-order bounds is examined in three numerical examples. These bounds can provide significant improvement over the second-order bounds, particularly when the number of significant failure modes is small (less than 20) or when the correlations between modes are somewhat localized.     

Evaluation of seismic reliability of gravity dam-reservoir-inhomogeneous foundation coupled system

The seismic performance of gravity dam-reservoir-foundation coupled system is investigated utilizing probabilistic approach. In this research, the uncertainties associated with modeling parameters are incorporated in nonlinear response history simulations to realistically quantify their effects on the seismic performance of the system. The methodology is applied to Pine Flat gravity dam and the foundation is considered to be inhomogeneous assuming a constant spatial geometry but with various rock material properties. The sources of uncertainty are taken into account in the reliability analysis using Latin Hypercube Sampling procedure. The effects of the deconvolution process, number of samples, and foundation inhomogeneity are investigated.