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1.
Decision-making for the rehabilitation of water distribution networks in the traditional procedure is based on some simple
indices such as the number of incidents while several mechanical, hydraulic and qualitative factors are involved in this process.
Evidently, making decision on the rehabilitation of water networks seems to be very difficult as the number of factors increases
and they interact with each other. The main objective of this research is to prepare, implement and evaluate a conceptual
model to prioritize the rehabilitation of pipes based on different scenarios with respect to the combination effects of basic
factors in physical, hydraulic and experimental categories. In order to organize the wide range of data to be used in decision-making
models, including the plans aimed for pipe replacement, it is necessary to use geographical information systems (GIS). By
determining and introducing the factors involved in the rehabilitation of water networks, this research aims to provide an
integrated model consisting of conceptual, GIS, hydraulic analysis and the breakage models to prioritize the rehabilitation
schemes. By using the data provided from a real network, the advantages of the proposed methodology are evaluated. Based on
the obtained results, age factor, among all the other physical parameters, and pressure, among the hydraulic factors, have
the greatest influence in outlining the final rehabilitation scenario. The importance of the pipe length has decreased considerably
as well. Furthermore, it can be concluded that rehabilitation management of pipe networks can be optimized by using this methodology. 相似文献
2.
Water shortage is experienced in different parts of the world in different magnitude. In certain countries, water deficit
is a regular phenomenon and in some other countries it happens for a short duration, due to failure of any component in the
system. Shortage of water at source can be best tackled by distributing the available water equally among the consumers. This
paper deals with the design of water distribution network capable of equitable supply during shortage in addition to the satisfactory
performance under non-deficit condition. Performance of a typical water distribution network, with shortage of water at source
is illustrated in detail. Head dependent outflow analysis with extended period simulation, is used to determine the actual
supply from each node to consumers. Relationship between duration of supply and volume available at source as well as supply
from each node are established for understanding the behaviour of network under low supply situation. A term “inequity” which
is the maximum difference in supply demand ratio among different consumers is presented. This is based on the actual performance
of the network instead of surrogate measures, generally used for reliability. It is illustrated that the maximum “inequity”
in supply in a network during the entire duration of supply can be estimated with single analysis. Design of a water distribution
network, duly considering equity in addition to the cost minimization and minimum head requirement is presented. Genetic Algorithm
is used for solving this multi objective problem. The solution technique is illustrated using two benchmark problems, namely
two loop network and Hanoi network. Results show that considerable improvement in equitable supply can be achieved with additional
investment on pipes above the least cost solution. Hence it is better to design networks duly considering deficit condition
for better reliability. It is also illustrated that it will be difficult to improve equity beyond a limit for a given network,
through selection of different pipe diameters. 相似文献
3.
借助Authorware5 0 ,并结合给水管网模型模拟计算软件的实际要求 ,制作了给水管网多媒体学习软件。从实际制作经验出发 ,提出了在多媒体学习软件开发中的技巧和方法。 相似文献
4.
微观建模在城市给水管网系统中的实践 总被引:8,自引:0,他引:8
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。 相似文献
5.
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. 相似文献
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本文提出了热网中热水管道以及蒸气管道中水温,蒸汽温度以及壁温的自动监控系统,利用此法可以快速地测定这些温度的动态响应,并以图示的方法表现出来,从而为热网的自动监控打下良好的基础。 相似文献
9.
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. 相似文献
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对城市庞大的供水管网进行普查是一项复杂的系统工程。通过对武汉市武昌区供水管网的普查工作 ,探索和总结了一套较有成效的工作方法和程序。 相似文献
14.
Pressure deficient condition occurs in the water distribution network (WDN) when the nodal demands are in excess of the design discharge as in the case of fire demand, pump failure, pipe breaks, valve failure etc. It causes either no-flow or partial-flow depending upon the available pressure head at the nodes. To evaluate the nodal flows in such condition, node flow analysis (NFA) gives reasonable results in comparison to demand-driven analysis (DDA) and head-dependent analysis (HDA). The NFA works on the predefined pressure-discharge relationship to evaluate the nodal flows. However, this approach requires human intervention and hence cannot be applied to large WDN. Recently, modified pressure-deficient network algorithm (M-PDNA) has been developed by Babu and Mohan (2012) for pressure-deficient analysis with EPANET toolkit. However, it requires modification of the source code of EPANET. In this study a relationship with the M-PDNA and node flow analysis (Gupta and Bhave 1996) has been investigated and it is found that M-PDNA is the simplified version of NFA. Further, the working principle of M-PDNA has been investigated with suitable examples of Babu and Mohan (2012). The theoretical basis of M-PDNA has not been investigated in terms of head-discharge relationship. Herein, a head-discharge relationship based on the working principal of M-PDNA is proposed. Some of the toolkits are also readily available to modify demand driven solver of EPANET 2 to suit for the pressure-driven analysis and then it can be used for analysing pressure deficient network. Also in this study, a modification in M-PDNA approach is proposed which does not require the use of EPANET toolkit which is found to be capable of simulating both pressure-sufficient and pressure-deficient conditions in a single hydraulic simulation. Using the proposed approach, pressure-deficient condition is analysed with constant and variable demand pattern. 相似文献
15.
Dire Dawa, the second largest city of Ethiopia, was facing about the distribution system adopted for supplying clean water. It was being observed that an intermittent type of supply with main and secondary distribution pipes. It was observed that, the current water demand has surpassed the present existing supply about 65%. Hence, in order to provide sufficient quantity and good potable water with continuous (24 X 7) water supply for various sectors of study area: Sabiyan region, Dire Dawa, Ethiopia, was selected. Also, Dire Dawa Water Supply & Sewerage Authority has taken a strong decision in order to validate and examine the existing water distribution network for improved water supply. On the other hand, the main important factor which effects the validation is that the age of pipes and other accessories in present existing network were longstanding. Therefore, to avoid the leakage losses and various problems encountered with the present system, a detailed is study is conducted and the analysis is carried out using EPANET tool to design for continuous water supply. After thorough analysis by considering future concerns, it was suggested that, two GLSRs of each with 2.7 Mm3 capacity may be provided in order to meet the future demands. The tanks are provided at required elevation to ensure that the water flows in all pipes of the network efficiently. Based on the output it was observed that the diameter of pipes from the existing system ought to be revised. Additionally, other parameters which effect the network like frictional losses, velocity of flow in the pipes, residual head and pressure at nodes were also examined thoroughly by the use of different tools like WaterGEMS and Auto CAD in addition to EPANET. 相似文献
16.
改善城市供水管网水质的实践与探讨 总被引:16,自引:2,他引:16
嘉兴水司出厂水流经管网以后 ,浊度、色度、总铁有时升高明显 ,主要原因为出厂水稳定性较差 ,大部分管网老化严重。针对这些问题采取了用新净水工艺 ,提高出厂水水质 ,取消屋顶水箱 ,加快旧的输配水管网改造等应对措施 相似文献
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Water Resources Management - Identifying critical facilities in a water distribution system (WDS) from the standpoint of recovery resilience is significant for emergency inspection and restoration... 相似文献
19.
Distribution Network Assessment using EPANET for Intermittent and Continuous Water Supply 总被引:1,自引:0,他引:1
Sanjeeb Mohapatra Aabha Sargaonkar Pawan Kumar Labhasetwar 《Water Resources Management》2014,28(11):3745-3759
Drawbacks of intermittent water supply system and inability to shift to continuous supply mode is the main challenge in developing countries. The suitability of the infrastructure laid over past two to three decades to meet the 24/7 demand of todays population is the issue for many water mangers. The present study addresses this issue using EPANET software for a pilot study area in Nagpur city, India. GIS maps, field survey data, remote sensing data and in-situ measurements of pressure and water quality are used in model simulation study. Total 96 artificial reservoirs are inserted into the network which replicate the end-user practices of excess water withdrawal. Reservoirs are assumed connected to damand nodes with equivalent diameter pipes for intermittent supply simulation. For continuous supply, demand multipliers are derived using Monte Carlo simulation. Bulk decay coefficient 0.17 day?1 for residual chlorine is used in water quality simulation. Simulation scenario of intermittency indicates existing network is not suitable to maintain desired headloss, and pressure in most of the pipes is very low (<1 m). Water age and water quality problems reveal that rehabilitation of distribution mains and critical pipes in the central part is primarily important before implementing 24/7 water supply scheme in the study area. 相似文献
20.
This paper describes a penalty-free multi-objective evolutionary optimization approach for the phased whole-life design and rehabilitation of water distribution systems. The optimization model considers the initial construction, rehabilitation and upgrading costs. Repairs and pipe failure costs are included. The model also takes into consideration the deterioration over time of both the structural integrity and hydraulic capacity of every pipe. The fitness of each solution is determined from the trade-off between its lifetime costs and its actual hydraulic properties. The hydraulic analysis approach used, known as pressure-dependent modelling, considers explicitly the pressure dependency of the water supply consumers receive. Results for two sample networks in the literature are included that show the algorithm is stable and finds optimal and near-optimal solutions reliably and efficiently. The results also suggest that the evolutionary sampling efficiency is very high. In other words, the number of solutions evolved and analysed on average before finding a near-optimal solution is small in comparison to the total number of feasible and infeasible solutions. We found better solutions than those reported previously in the literature for the two networks considered. For the Kadu network, for example, the new best solution costs Rs125,460,980—a significant improvement. Additional statistics that are based on extensive testing are included. 相似文献