Equilibrating Pressure with Auto-Control Valve in Water Distribution Networks

This paper probes into the feasibility of equilibrating pressure of water distribution network through (using auto-control valves) in theory and in the economy. An optimal valve control model is designed to minimize the sum of squares of residual pressure in the network. Such an analog simulation has been performed on the year 2003 programming network of a certain littoral district in North China, through which this paper confirms that it is feasible to equilibrate pressure with auto-control valves in theory. The research work has brought about a discovery of applicable conditions of valves in economic feasibility, which avoids a great economic loss due to the wild use of auto-control valve. In addition, simulated annealing algorithm is applied to optimize valve settings and shown to identify global optimum or near-optimum.

Optimal operation of water distribution networks under local pipe failures

The optimal operation of water distribution networks under local pipe failures, such as water main breaks, was proposed. Based on a hydraulic analysis and a simulation of water distribution networks, a macroscopic model for a network under a local pipe failure was established by the statistical regression. After the operation objectives under a local pipe failure were determined, the optimal operation model was developed and solved by the genetic algorithm. The program was developed and examined by a city distribution network. The optimal operation alternative shows that the electricity cost is saved approximately 11%, the income of the water corporation is increased approximately 5%, and the pressure in the water distribution network is distributed evenly to ensure the network safe operation. Therefore, the proposed method for optimal operation under local pipe failure is feasible and cost-effective.

Calculation of the Water Distribution Networks Based on the Theory of Slow Transient Flow

Urban water supply network is a modern urban survival and development of the infrastructure of a city,and its normal running conditions have important significance. The actual hydraulic process in the variableload water distribution networks can be treated as the slow transient flow which belongs to the unsteady flow. This paper analyzes the multi-loops network slow transient model based on graph theory,and the link flow matrix is treated as the variables of the discrete solution model to simulate the process of the slow transient flow in the network. With the simulation of hydraulic regime in an actual pipe network,the changing laws of the flow in the pipes,nodal hydraulic heads and other hydraulic factors with the passage of time are obtained. Since the transient processes offer much more information than a steady process,the slow transient theory is not only practical on analyzing the hydraulic condition of the network,but also on identifying hydraulic resistance coefficients of pipes and detecting the leakage in networks.

Identification of sources of pollution and contamination in water distribution networks based on pattern recognition

An intrusion of contaminants into the water distribution network (WDN) can occur through storage tanks (via animals, dust-carrying bacteria, and infiltration) and pipes. A sensor network could yield useful observations that help identify the location of the source, the strength, the time of occurrence, and the duration of contamination. This paper proposes a methodology for identifying the contamination sources in a water distribution system, which identifies the key characteristics of contamination, such as location, starting time, and injection rates at different time intervals. Based on simplified hypotheses and associated with a high computational efficiency, the methodology is designed to be a simple and easy-to-use tool for water companies to ensure rapid identification of the contamination sources, The proposed methodology identifies the characteristics of pollution sources by matching the dynamic patterns of the simulated and measured concentrations. The application of this methodology to a literature network and a real WDN are illustrated with the aid of an example. The results showed that if contaminants are transported from the sources to the sensors at intervals, then this method can identify the most possible ones from candidate pollution sources. However, if the contamination data is minimal, a greater number of redundant contamination source nodes will be present. Consequently, more data from different sensors obtained through network monitoring are required to effectively use this method for locating multi-sources of contamination in the WDN.

Application of Dynamic Programming Method in Optimization of Water Distribution Pipe Network

With a water-supply network by dynamic programming. The minimal as an example, the network was optimized annual discounted costs were taken as an objective function and node pressure etc. as constraint conditions. The alternative pipe diameters were optimized as per enumeration method and the group allowing objective function with the least values would be the optimized one. It is proved the optimized pipe network reduced by 11.49% in terms of cost and the optimized ben- efits proved much significant.

STUDY ON OPTIMAL CONTROL OF MUNICIPAL WATER DISTRIBUTION NETWORK

A systematic investigation is made on the problems which are related to the optimal control of the municipal water distribution network.A mathematical model of forecasting the water short term demand is proposed using the time series trigonometric function analysis method;the service discharge based macroscopic model of network performance is established using the network structuring method;a relatively satisfactory mathematical model for the optimal control of water distribution network is put forward in view of security and economy,and solved by the constrained mixed discrete variable complex arithmetic.The model is applied in many examples and the results are satisfactory.

Partitioning of Water Distribution Network into District Metered Areas Using Existing Valves

Water distribution network(WDN)leakage management has received increased attention in recent years.One of the most successful leakage-control strategies is to divide the network into District Metered Areas(DMAs).As a multi-staged technique,the generation of DMAs is a difficult task in design and implementation(i.e.,clustering,sectorization,and performance evaluation).Previous studies on DMAs implementation did not consider the potential use of existing valves in achieving the objective.In this work,a methodology is proposed for detecting clusters and reducing the cost of additional valves and DMA sectorization by considering existing valves as much as possible.The procedure of DMAs identification has been divided into three stages,i.e.,a)clusters identification;b)sectorization or boundaries optimization and c)performance evaluation of the partitioned network.The proposed methodology is evaluated on a simple network and a real-world water network with the findings provided and compared to the DMAs,established for a raw water network with no existing valves.It is found that there is an adequate difference in cost of strategy implementation in both the cases for the network under consideration and the existing valve system achieved better network performance in terms of resilience index.

Identification of contamination source in water distribution network based on consumer complaints

A new methodology was proposed for contamination source identification using information provided by consumer complaints from a probabilistic view.Due to the high uncertainties of information derived from users,the objective of the proposed methodology doesn't aim to capture a unique solution,but to minimize the number of possible contamination sources.In the proposed methodology,all the possible pollution nodes are identified through the CSA methodology firstly.And then based on the principle of total probability formula,the probability of each possible contamination node is obtained through a series of calculation.According to magnitude of the probability,the number of possible pollution nodes is minimized.The effectiveness and feasibility of the methodology is demonstrated through an application to a real case of ZJ City.Four scenarios were designed to investigate the influence of different uncertainties on the results in this case.The results show that pollutant concentration,injection duration,the number of consumer complaints nodes used for calculation and the prior probability with which consumers would complaint have no particular effect on the identification of contamination source.Three nodes were selected as the most possible pollution sources in water pipe network of ZJ City which includes more than 3 000 nodes.The results show the potential of the proposed method to identify contamination source through consumer complaints.

Seismic reliability analysis of urban water distribution network

An approach to analyze the seismic reliability of water distribution networks by combining a hydraulic analysis with a first-order reliability method （FORM）, is proposed in this paper. The hydraulic analysis method for normal conditions is modified to accommodate the special conditions necessary to perform a seismic hydraulic analysis. In order to calculate the leakage area and leaking flow of the pipelines in the hydraulic analysis method, a new leakage model established from the seismic response analysis of buried pipelines is presented. To validate the proposed approach, a network with 17 nodes and 24 pipelines is investigated in detail. The approach is also applied to an actual project consisting of 463 nodes and 767 pipelines. The results show that the proposed approach achieves satisfactory results in analyzing the seismic reliability of large-scale water distribution networks.

Investigation of factors affecting rural drinking water consumption using intelligent hybrid models

Identifying the factors affecting drinking water consumption is essential to the rational management of water resources and effective environment protection. In this study, the effects of the factors on rural drinking water demand were studied using the adaptive neuro-fuzzy inference system (ANFIS) and hybrid models, such as the ANFIS-genetic algorithm (GA), ANFIS-particle swarm optimization (PSO), and support vector machine (SVM)-simulated annealing (SA). The rural areas of Hamadan Province in Iran were selected for the case study. Five drinking water consumption factors were selected for the assessment according to the literature, data availability, and the characteristics of the study area (such as precipitation, relative humidity, temperature, the number of subscribers, and water price). The results showed that the standard errors of ANFIS, ANFIS-GA, ANFIS-PSO, and SVM-SA were 0.669, 0.619, 0.705, and 0.578, respectively. Therefore, the hybrid model SVM-SA outperformed other models. The sensitivity analysis showed that of the parameters affecting drinking water consumption, the number of subscribers significantly affected the water consumption rate, while the average temperature was the least significant factor. Water price was a factor that could be easily controlled, but it was always one of the least effective parameters due to the low water fee.

Optimal locations of monitoring stations in water distribution systems under multiple demand patterns： a flaw of demand coverage method and modification

A flaw of demand coverage method in solving optimal monitoring stations problem under multiple demand patterns was identified in this paper. In the demand coverage method, the demand coverage of each set of monitoring stations is calculated by accumulating their demand coverage under each demand pattern, and the impact of temporal distribution between different time periods or demand patterns is ignored. This could lead to miscalculation of the optimal locations of the monitoring stations. To overcome this flaw, this paper presents a Demand Coverage Index （DCI） based method. The optimization considers extended period unsteady hydrau- lics due to the change of nodal demands with time. The method is cast in a genetic algorithm framework for integration with Environmental Protection Agency Net （EPANET） and is demonstrated through example applica- tions. Results show that the set of optimal locations of monitoring stations obtained using the DCI method can represent the water quality of water distribution systems under multiple demand patterns better than the one obtained using previous methods.

Hazard and vulnerability evaluation of water distribution system in cases of contamination intrusion accidents

In this paper, it proposed an index system for hazard and vulnerability evaluations of water distribution networks, based on the simulation of contamination events caused by pollutant injections at different junctions. It attempted to answer the following two questions in the case of contamination events： 1） Which are the most hazardous junctions？ 2） Which are the most vulnerable junctions？ With EPANET toolkit, it simulated the propagation of the contaminant, and calculated the peak concentration of the contaminant and mass delivered at different nodes. According to types of consumers, different weights were assigned to the consumer nodes for assessing the influence of the contaminant on the consumers. Using the method proposed herein, both the hazard index and vulnerability index were calculated for each node in the pipe network. The presented method was therefore applied to the water network of the city of Zhenjiang, which contains two water plants, two booster pump stations with storage tanks. In conclusion, the response time, the relationships between the peak concentration of contami- nant and the total absorption are the most important factors in hazard and vulnerability evaluation of the water distribution network.

Bacteriological challenges to asbestos cement water distribution pipelines

Asbestos cement （AC） pipes were commonly installed in the drinking water distribution systems from the mid 1920s to the late 1980s. In recent years, an increase in the number of water main breaks has occurred in the AC portions of some pipe networks, which can be partially attributed to the corrosion of the aged pipes. This study evaluated the potential role that microorganisms may have played in the degeneration and failure of AC pipes. In this study, a fresh AC pipe section was collected from the distribution network of the City of Regina, Canada and examined for microbiological activities and growth on inside surfaces of pipe sample. Black slime bacterial growths were found to be attached to inner pipe surfaces and a distinctively fibrous internal coating （patina） with iron oxides was formed over the time. The microbial populations inside the patina and the black slime were tested with BART^TM testers. Heterotrophic aerobic bacteria （HAB） and slime forming bacteria （SLYM） dominated in both the black growths and inside the patina. Iron related bacteria, denitrification bacteria and sulfate reducing bacteria were also commonly present. Microbial challenge assays were conducted by submerging the cut segments of the AC pipe into selected bacterial cultures for a period of 10 days under both aerobic and anaerobic environments. Weight changes were determined and the surface morphology was examined for each of the assayed pipe segments. Results indicated that acid producing bacteria, SLYM and HAB could facilitate the pipe weight loss under anaerobic environments.

Algorithms for seismic topology optimization of water distribution network

As an essential lifeline engineering system,water distribution network should provide enough water to maintain people's life after earthquake in addition to working under daily operation.However,the design of water distribution network usually ignores the influence of earthquake,resulting in water stoppage in large area during many recent strong earthquakes.This study introduced a seismic design approach of water distribution network,i.e.,topology optimization design.With network topology as the optimization goal and seismic reliability as the constraint,a topology optimization model for designing water distribution network under earthquake is established.Meanwhile,two element investment importance indexes,a pipeline investment importance index and a diameter investment importance index,are introduced to evaluate the importance of pipelines in water distribution network.Then,four combinational optimization algorithms,a genetic algorithm,a simulated annealing genetic algorithm,an ant colony algorithm and a particle swarm algorithm,are introduced to solve this optimization model.Moreover,these optimization algorithms are used to optimize a network with 19 nodes and 27 pipelines.The optimization results of these algorithms are compared with each other.

Per-unit Scheme for Integrated Solution of Hybrid Power-water Flow Problem

When applying the widely-used Newton-Raphson(N-R)method to the integrated solution of the hybrid power-water flow problem of the power-water integrated energy system(PW-IES),it is found that there are numerical differences among Jacobian elements,which may yield an ill-conditioned Jacobian matrix and even cause convergence problem.Therefore,this letter proposes to per-unitize the water distribution network(WDN)to reduce the numerical differences and thus to improve the Jacobian matrix conditioning and the integrated N-R solution to the hybrid power-water flow problem.

Dynamic Scheduling Algorithm Based on Evolutionary Reinforcement Learning for Sudden Contaminant Events Under Uncertain Environment

For sudden drinking water pollution event,reasonable opening or closing valves and hydrants in a water distribution network(WDN),which ensures the isolation and discharge of contaminant as soon as possible,is considered as an effective emergency measure.In this paper,we propose an emergency scheduling algorithm based on evolutionary reinforcement learning(ERL),which can train a good scheduling policy by the combination of the evolutionary computation(EC)and reinforcement learning(RL).Then,the optimal scheduling policy can guide the operation of valves and hydrants in real time based on sensor information,and protect people from the risk of contaminated water.Experiments verify our algorithm can achieve good results and effectively reduce the impact of pollution events.