Discussion of 'Optimal Design of Redundant Water Distribution Networks Using a Cluster of Workstations' by Sujay V. Kumar, Troy A. Doby, John W. Baugh Jr., E. Downey Brill, and S. Ranji Ranjithan

摘要

The authors have clustered nondedicated workstations and used asynchronous distributed genetic algorithm (GA) effectively for the optimal design of redundant water distribution networks (WDNs). This approach of the authors is commendable, since GA is computationally intensive especially for the redundancy-based design of practical WDNs. The level of redundancy of a WDN is defined as the number of simultaneous pipe outages the network can sustain without affecting consumer services either in part or in full. Thus, a Level 1 redundant solution of a WDN should meet the flow and pressure requirements in the event of a single pipe outage in the network. Similarly, a Level 2 redundant solution should meet the requirements in the event of outage of any two pipes. However, before assuring the hydraulic redundancy, it is necessary to assure the appropriate topologic redundancy of the desired level in the network (Kessler et al. 1990; Ormsbee and Kessler 1990; Agrawal et al. 2007). All nodes, including the source node, in a single source network should be connected by at least two pipes for a Level 1 redundant system, so that in the event of outage of any one pipe, no node is isolated from the network. For a Level 2 redundant system, all nodes should have at least three connected pipes. The authors have not considered the topologic redundancy of the appropriate level in the illustrative design problems. Therefore, the design solutions they obtained do not truly depict the Level 1 and Level 2 redundancies.