Linear programming gradient (LPG) method is an important method for the optimum design of looped water distribution systems, but the complex algorithm and slow convergence restrict its applications. In this paper, the design of the looped water distribution system is considered as a linear programming with variable coefficients. The derivatives of the cost with respect to pipe flows for water distribution system are deduced accurately for the first time. An efficient iterative algorithm for searching the optimum pipe flows is developed. An example is presented. It is shown that the new algorithm has better convergence than present algorithms

Water Resources ResearchVolume 15, Issue 6 p. 1651-1654 CommentariesFree Access Comment on ‘Design of optimal water distribution systems’ by E. Alperovits and U. Shamir G. E. Quindry, G. E. QuindrySearch for more papers by this authorE. D. Brill Jr., E. D. Brill Jr.Search for more papers by this authorJ. C. Liebman, J. C. LiebmanSearch for more papers by this authorA. R. Robinson, A. R. RobinsonSearch for more papers by this author G. E. Quindry, G. E. QuindrySearch for more papers by this authorE. D. Brill Jr., E. D. Brill Jr.Search for more papers by this authorJ. C. Liebman, J. C. LiebmanSearch for more papers by this authorA. R. Robinson, A. R. RobinsonSearch for more papers by this author First published: December 1979 https://doi.org/10.1029/WR015i006p01651Citations: 39AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat References Alperovits, E., U. Shamir, Design of optimal water distribution systems, Water Resour. Res., 136, 885–900, 1977. Citing Literature Volume15, Issue6December 1979Pages 1651-1654 ReferencesRelatedInformation

A series of experiments was conducted to determine the performance characteristics of the methane fermentation process using beef feed lot manure as a substrate. Manure was obtained from the University of Illinois beef farm. This manure was processed through four parallel fermentors each having a capacity of 775 liters. A continuous feed system was employed to determine the conversion efficiency. The effluent from the fermentation units was evaluated to determine its dewatering characteristics and the quality of the liquid and solid residues. A simple simulation model was developed to evaluate the effect of various operating conditions on processing costs and the net income. These studies clearly show that thermophilic fermentation (58 to 60/sup 0/C) substantially increase the gas yield and the rate of gas production over that obtained at the mesophilic fermentation temperature. System stability is very good. Substantial decreases in temperature or significant increases in loadings did not disrupt the process. Solids recovery from the fermented slurry was accomplished with screens, vacuum drum filters and centrifuge. Solids capture was poor unless massive dosags of conditioning chemicals were added. In terms of investment and operating costs, simple screens (20 mesh size) would capture 75 to 80 percent of the recoverable suspended solids. Manure that is obtained from open lots, especially when it has been exposed to the environment for extended periods, offers little potential for methane production. The biodegradability of this material is so low that the cost of producing the gas far exceeds its value. Fresh manure such as that obtained from environmental lots produced significant quantities of gas. It is probable that an economic system can be developed using this material as a substrate.