Optimal Design Of Water Distribution Networks Research Articles

Multi-objective Rao algorithm in resilience-based optimal design of water distribution networks

Abstract Multi-objective meta-heuristics are used to optimize water distribution networks (WDNs) as they can achieve a near-optimal balance between cost and resilience in a unified platform. Most of these algorithms include tuning of algorithm-specific control parameters for higher optimization efficiency, leading to an increased computational effort. The current study is inspired by the desire to address the above problem. The goal is to formulate a multi-objective Rao algorithm (MORao) considering an existing modified resilience index (MRI) in the optimal design of WDNs. The model is demonstrated to attain Pareto-optimal solutions to complex WDN problems without exclusive parameter tuning. The algorithm is written in Python and is linked to a hydraulic model of a WDN implemented in EPANET 2.2 using pressure-driven demand (PDD) analysis. The method is demonstrated on three widely used networks: Two-loop, Goyang, and Fossolo. The Pareto-optimal solutions examine a tradeoff between two objectives to recognize competitive solutions. The network's resilience is increased 2.5 times by only 0.8 times increase in least-cost of Two-loop network. This research indicates that this method can achieve a satisfactory level of performance with a limited number of function evaluations.

Flow-Uniformity Index for Reliable-Based Optimal Design of Water-Distribution Networks

AbstractThe reliability of water distribution network (WDN) designs for satisfying water demands under normal and abnormal operating conditions, including during pipe bursts and as systems age, is ...

A New Method for Quasi-Optimal Design of Water Distribution Networks

In recent years optimal design of water distribution networks (WDNs) has been a subject of interest to several researchers. In this regard, in the previous researches various optimization techniques such as linear and non-linear programming and also meta-heuristic algorithms have been used for optimal design of WDNs. Among these techniques, meta-heuristic algorithms have shown the best performance. One of the disadvantages of implementing these methods for optimizing of WDNs is their high computational costs which make their usage sometimes impossible for large real life WDNs. In this paper a new method for quasi-optimal design of WDNs is presented. In the proposed method that is based on some hydraulic rules, diameters are selected so that the energy loss per unit length of pipes will be in a specific range. Using this method and without any requirement to available optimization techniques, design of WDNs can be done in a lower time relative to the mentioned techniques, so that the cost of the designed network will be very close to the least cost. Two sample networks have been designed using the proposed new method. Comparison of the obtained results with the available optimization techniques indicates the ability of this method to find the near optimal solutions in the shortest time.

Reliability-based optimal design of water distribution networks under uncertain demands using cross-entropy method

The performance of water distribution networks (WDNs) is often measured in terms of the reliability in meeting its demands. In this paper, a methodology based on cross-entropy (CE) is presented for optimal design of WDN by considering the uncertainty in nodal demands. The nodal demands are considered as random variables and their associated uncertainties are represented by normal distributions. The CE-based methodology is applied for two case studies, namely, two-loop WDN and Hanoi WDN design under uncertain nodal demands, and the solutions are compared with deterministic model solutions. It is found that the CE method is an attractive alternative technique for optimization of the WDNs that involves discrete diameters as decision variables. Also, the presented methodology provides a mechanism to incorporate network reliability into the optimal design of WDNs and helps to analyse the tradeoffs between system reliabilities and their associated costs.

Optimal Design of Water-Distribution Networks with GIS

Many powerful optimal desgin models have been developed for municipal water-distribution networks, but few are in practical use since they are difficult for water engineers to understand and require an extensive data base for implementation. To aid in technology transfer of water-distribution system optimizers, a prototype decision support system WADSOP (Water Distribution System Optimization Program) is presented to guide water-distribution system design and analysis in response to changing water demands, timing, and use patterns; and accommodation of new developments. WADSOP integrates a geographic information system (GIS) for spatial database management and analysis with optimization theory to provide a computer-aided decision support tool for water engineers. Several comparative studies show improved performance over published results. A real-world case study for the city of Greeley, Colo., water-distribution network is also presented.

Incorporating reliability in optimal design of water distribution networks—review and new concepts

Abstract Much of the effort in optimal design of water distribution networks (WDNs) has focussed so far on minimizing cost alone, with little emphasis on reliability or on investigating the tradeoff between cost and reliability. This is a consequence of the difficulty in defining reliability measures which are meaningful and appropriate, while still of a form which can be incorporated directly into optimization models. This paper will deal with these issues. It contains three parts: (1) conceptual discussion of reliability definitions from different points of view (system versus consumers), (2) a literature survey of existing techniques to incorporate reliability in the optimal design of WDNs, and (3) a new concept for explicitly including reliability in the optimal design of WDNs.