دانلود رایگان مقاله مقایسه عملکرد مدل کاهشی برای تشخیص نشت در شبکه توزیع آب

Abstract

This paper presents a methodology for comparing the performance of model-reduction strategies to be used with a diagnostic methodology for leak detection in water distribution networks. The goal is to find reduction strategies that are suitable for error-domain model falsification, a model based data interpretation methodology. Twelve reduction strategies are derived from five strategy categories. Categories differ according to the manner in which nodes are selected for deletion. A node is selected for deletion according to: (1) the diameter of the pipes; (2) the number of pipes linked to a node; (3) the angle of the pipes in the case of two-pipe nodes; (4) the distribution of the water demand; and, (5) a pair-wise combination of some categories. The methodology is illustrated using part of a real network. Performance is evaluated first by judging the equivalency of the reduced network with the initial network (before the application of any reduction procedure) and secondly, by assessing the compatibility with the diagnostic methodology. The results show that for each reduction strategy the equivalency of networks is verified. Computational time can be reduced to less than 20% of the non-reduced network in the best case. Results of diagnostic performance show that the performance decreases when using reduced networks. The reduction strategy with the best diagnostic performance is that based on the angle of two-pipe nodes, with an angle threshold of 165°. In addition, the sensitivity of the performance of the reduced networks to variation in leak intensity is evaluated. Results show that the reduction strategies where the number of nodes is significantly reduced are the most sensitive. Finally this paper describes a Pareto analysis that is used to select the reduction strategy that is a good compromise between reduction of computational time and performance of the diagnosis. In this context, the extension strategy is the most attractive.

6. Conclusions

The analysis of the results leads to the following conclusions. Reduction strategies used in this paper are useful for reproducing flows with simplified networks. Since it is possible to reduce computational time to up to 20% of the time for the non-reduced network, gains can be significant. The strategies that reduce computational time the most are also those which are most sensitive to leak severity. Strong network reduction may lead to decreased performance for small leaks faster than networks with lighter reduction. The reduction procedures that are most suited for leak detection using model falsification are Consumption 10%, Extension and Angle 135. A Pareto analysis shows that a good compromise between the reduction of computational time and diagnostic performance is given by the Extension reduction strategy.