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Showing 4 results for Pipe Networks

Afshar M.h.,
Volume 1, Issue 1 (9-2003)
Abstract

In this paper the analysis of the pipe networks is formulated as a nonlinear unconstrained optimization problem and solved by a general purpose optimization tool. The formulation is based on the minimization of the total potential energy of the network with respect to the nodal heads. An analogy with the analysis of the skeletal structures is used to derive tire formulation. The proposed formulation owes its significance for use in pipe network optimization algorithms. The ability and versatility of the method to simulate different pipe networks are numerically tested and the accuracy of the results is compared with direct network algorithms.
M.h. Afshar, M.r. Ghasemi,
Volume 3, Issue 2 (6-2005)
Abstract

An efficient selection operator for use in genetic search of pipe networks optimal design is introduced in this paper. The proposed selection scheme is the superior member of a family of improved selection operators developed in an attempt to more closely simulate the main features of the natural mating process which is not reflected in existing selection schemes. The mating process occurring in the nature exhibits two distinct features. First, there is a competition between phenotypes looking for the fittest possible mate which usually ends up with choosing a mate with more or less the same fitness. Second, and more importantly, the search for a mate is often confined to a community of phenotypes rather than the whole population. Four different selection operators simulating these features in a random and pre-determined manner are developed and tested. All the selection schemes exhibit good convergence characteristics, in particular the one in which both the size of the sub-community and the pair of the mates in the sub-community are determined randomly. The efficiency of the proposed selection operator is shown by applying the method for the optimal design of three well-known benchmark networks, namely two-loop, Hanoi and New-York networks. The proposed scheme produces results comparable to the best results presented in the literature with much less computational effort
M.h. Afshar, A. Afshar, M. A. Mariño, Hon. M. Asce,
Volume 7, Issue 2 (6-2009)
Abstract

This paper presents the application of an iterative penalty method for the design of water distribution pipe networks. The optimal design of pipe networks is first recasted into an unconstrained minimization problem via the use of the penalty method, which is then solved by a global mathematical optimization tool. The difficulty of using a trial and error procedure to select the proper value of the penalty parameter is overcome by an iterative use of the penalty parameter. The proposed method reduces the original problem with a priori unknown penalty parameter to a series of similar optimization problems with known and increasing value of the penalty parameters. An iterative use of the penalty parameter is then implemented and its effect on the final solution is investigated. Two different methods of fitting, namely least squares and cubic splines, are used to continuously approximate the discrete pipe cost function and are tested by numerical examples. The method is applied to some benchmark examples and the results are compared with other global optimization approaches. The proposed method is shown to be comparable to existing global optimization methods.
Mohammad Hadi Ranginkaman, Ali Haghighi, Hossein Mohammad Vali Samani,
Volume 15, Issue 4 (6-2017)
Abstract

This paper investigates the frequency response method for waterhammer phenomenon in piping networks. The unsteady flow governing equations are solved in time domain using the method of characteristics. They are also solved in frequency domain using the transfer matrix method. For the pipe network under consideration, critical transient excitation scenarios are identified. For each scenario, the frequency responses of the system as well as the time history of the transient pressures at the network nodes are calculated. The model is applied against a real pipe network and the results of the transfer matrix method are compared with those of the method of characteristics. It is concluded that the frequency response method not only presents a very fast algorithm for analyzing pipe systems but also, has an acceptable accuracy compared to the method of characteristics. The frequency response method requires linearization in some terms of the governing equations. Instead of that, it needs no computational discretization and interpolation necessary in time-space domains when using the method of characteristics.



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