谱聚类在给水管网分区优化中的应用

利用图划分技术和图论算法实现给水管网分区。根据给水管网分析,确定分区数量,建立权重邻接矩阵并计算图拉普拉斯矩阵及其特征向量,通过多路图划分对隐藏在特征向量中的聚类信息进行数据挖掘,采用遗传算法和K均值方法实现最佳节点聚类。利用PageRank和最短路径算法确定水表和阀门位置,最终实现给水管网优化分区。实际给水管网模型分区实例表明所提方法在给水管网分区的有效性。     

Optimal joint deployment of flow and pressure sensors for leak identification in water distribution networks

ABSTRACT

A multi-objective optimization methodology is proposed herein for accurate identification of leakage in water distribution networks (WDNs) using pressure and flow sensors. We first model leakage at potential nodes using the EPANET software, and then divide WDN into near-homogenous zones using k-means clustering algorithm based on geographic distribution of nodes. Finally, flow and pressure sensors locations are optimized using the NSGA-II algorithm to identify the leakage zone accurately. Novelty of the proposed approach lies in sequential optimization of flow and pressure sensors placement, which helps improve the accuracy of leakage zone identification in WDNs. The objective functions of this study are: 1) maximizing accuracy of identified leakage zone and 2) minimizing number of sensors (and hence operational costs). Simulation results of the Mesopolis WDN corroborate the efficiency and effectiveness of the proposed approach.     

分区计量供水管网水力模型的流量分配

结合天津市供水管网实例,通过分析其计量水量的特点与水力模型的构建要求,按照水量数据来源分别侧重于小区表、户表和在线流量计,提供了分区计量供水管网水力模型的三个流量分配方案;从数据健全度、流量分配准确度、实施难度、流量分配校正依据、漏损考察功能、模型动态模拟、模型维护与应用难度和模型构建平台八个方面对三个流量分配方案进行了多角度评价,可为水力模型项目的实施提供参考。     

基于加权最小二乘法的供水管网节点流量校核

管网水力模型是实现供水系统现代化管理的重要工具,要使水力模型能比较准确地反映管网真实运行状态,达到预期使用目的,其中的参数需要校核。将管网节点流量校核作为优化问题,采用加权最小二乘法逐步迭代求解,与已有研究相比,采用矩阵分析法推导供水管网雅克比矩阵解析式,引入水量分配矩阵聚合节点流量,将欠定问题转化为超定,提高了校核的计算效率和结果的可靠性。采用简单管网阐明了雅克比矩阵的计算、节点流量的聚合及梯度向量的构造,利用实际管网验证了方法的实用性。     

A review of data-driven approaches for burst detection in water distribution systems

This study focuses on data-driven approaches for burst detection and classifies them into three categories: classification method, prediction-classification method and statistical method. The performance of these methods is discussed. By analysing uncertainty in burst detection, this paper revealed that non-stationary monitoring data and limitations present in these methods challenge the reliability of detection results. Data pre-processing and probabilistic solutions to deal with the uncertainty are summarised. From these findings and discussions, this paper concludes and recommends that: a) data-driven approaches are promising in real-life burst detection and reducing false alarms is an important issue; b) more comprehensive performance evaluation might be necessary, in particular regarding detectable burst size; c) further research on new methods employing multivariate analysis and a new category based on clustering analysis would be beneficial to tackle uncertainty; d) more focus on the use of pressure data might facilitate burst location and reduce investment in burst detection.     

Spatial distribution of ductility demand and damage index in 3D RC frame structures considering directionality effects

Most of studies that examined the influence of incidence angles of bidirection ground excitations were focused on the estimation of engineering demand parameters (EDPs) only along two orthogonal axes varying ground motion orientations. However, variations of the EDPs have not been assessed in a desired horizontal angular distance from a reference direction that could be different than the incident angle. Furthermore, the structural demands along the height of structures were not also studied for different angles of the incident of ground motion. The current paper aims to assess these issues introducing spatial distribution of ductility demands and damage index induced to multi‐storey reinforced concrete frames due to incidence‐dependent bidirection ground excitations. Employing the concept of 3D archetypical frames, several pushover analyses and nonlinear response history analyses were conducted using two sets of ground motions classified as near‐field and far‐field records. The results of these comprehensive parametric analyses including the EDPs along different angular distances from a reference point were employed to perform regression analyses obtaining the critical EDPs. Several expressions for the critical EDPs (mostly oriented in non‐principal planar directions) are suggested in terms of the orthogonal peak responses assumed to be assessed corresponding to the principal axes. Different expressions proposed in this study could be used to predict the critical ductility of structures by combining the structural ductility in two perpendicular directions when they are assessed due to the principal directions of excitations. Copyright © 2015 John Wiley & Sons, Ltd.