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Mohammad Hadi Afshar - One of the best experts on this subject based on the ideXlab platform.

  • Sewer Network Design Optimization Problem Using Ant Colony Optimization Algorithm and Tree Growing Algorithm
    EVOLVE - A Bridge between Probability Set Oriented Numerics and Evolutionary Computation IV, 2013
    Co-Authors: R. Moeini, Mohammad Hadi Afshar
    Abstract:

    This paper presents an adaptation of the Ant Colony Optimization Algorithm (ACOA) for the efficient layout and Pipe Size optimization of sewer network. ACOA has a unique feature namely incremental solution building mechanism which is used here for this problem. Layout and Pipe Size optimization of sewer network is a highly constrained Mixed-Integer Nonlinear Programming (MINLP) problem presenting a challenge even to the modern heuristic search methods. ACOA equipped with a Tree Growing Algorithm (TGA) is proposed in this paper for the simultaneous layout and Pipe Size determination of sewer networks. The TGA is used in an incremental manner to construct feasible tree-like layouts out of the base layout, while the ACOA is used to optimally determine the cover depths of the constructed layout. Proposed formulation is used to solve three test examples of different scales and the results are presented and compared with other existing methods. The results indicate the efficiency of the proposed method to optimally solve the problem of layout and Size determination of sewer network.

  • Constrained Ant Colony Optimisation Algorithm for the layout and Size optimisation of sanitary sewer networks
    Urban Water Journal, 2013
    Co-Authors: R. Moeini, Mohammad Hadi Afshar
    Abstract:

    The incremental solution building capability of Ant Colony Optimisation Algorithm (ACOA) is used in this paper for the efficient layout and Pipe Size optimisation of sanitary sewer network. Layout and Pipe Size optimisation of sanitary sewer networks requires optimal determination of Pipe locations, Pipe diameters and Pipe slopes leading to a highly constrained mixed-integer nonlinear programming (MINLP) problem presenting a challenge even to the modern heuristic search methods. A constrained version of ACOA equipped with a Tree Growing Algorithm (TGA) is proposed in this paper for the simultaneous layout and Pipe Size determination of sewer networks. The method is based on the assumption that a base layout including all possible links of the network is available. The TGA algorithm is used in an incremental manner to construct feasible tree-like layouts out of the base layout, while the constrained ACOA is used to optimally determine the cover depths of the constructed layout. Proposed formulation is used...

  • Layout and Size optimization of sanitary sewer network using intelligent ants
    Advances in Engineering Software, 2012
    Co-Authors: R. Moeini, Mohammad Hadi Afshar
    Abstract:

    The incremental solution building capability of ant algorithm is exploited in this paper for the efficient layout and Pipe Size optimization of sanitary sewer network. Layout and Pipe Size optimization of sewer networks requires that the Pipe locations, Pipe diameters and Pipe slopes are optimally determined. This problem is a highly constrained Mixed-Integer Nonlinear Programming (MINLP) problem presenting a challenge even to the modern heuristic search methods. In this paper, the Ant Colony Optimization Algorithm (ACOA) is equipped with a Tree Growing Algorithm (TGA) to efficiently solve the sewer network layout and Size optimization problem and its performance is compared with the conventional application of the ACOA. The method is based on the assumption that a base layout including all possible links of the network is available. The TGA is used to construct feasible tree-like layouts out of the base layout defined for the sewer network, while the ACOA is used to optimally determine the Pipe diameters of the constructed layout. An assumption of sewer flow at maximum allowable relative depth is made allowing for the calculation of the optimal Pipe slopes in the absence of any pump and drop in the network. Two different formulations are, therefore, proposed and their performances are tested against hypothetical problems. In the first formulation, ACOA is used in a conventional manner for Pipe Size optimization while an ad hoc engineering concept for the layout determination. In the second formulation, however, ACOA equipped with TGA is used to simultaneously determine both the layout and Pipe Sizes of the network. Proposed formulations are used to solve three hypothetical test examples of different scales and the results are presented and compared. The results indicate the ability of the proposed method to optimally solve the problem of layout and Size determination of sewer networks.

  • EVALUATION OF SELECTION ALGORITHMS FOR SIMULTANEOUS LAYOUT AND Pipe Size OPTIMIZATION OF WATER DISTRIBUTION NETWORKS
    Scientia Iranica, 2007
    Co-Authors: Mohammad Hadi Afshar
    Abstract:

    In this paper, a genetic algorithm is presented for the simultaneous layout and Pipe Size optimization of water distribution networks and its eciency is evaluated and compared using dierent selection mechanisms. An engineering concept of reliability is used, in which the number of independent paths from source nodes to each of the demand nodes is considered as a measure of reliability. The method starts with a predened layout, which includes all possible links. The method is capable of designing a layout of predened reliability, including tree-like and looped networks. It is shown that a layout optimization of a network, followed by Size optimization, does not lead to an optimal or a near-optimal solution. This emphaSizes the need for simultaneous layout and Size optimization of networks, if an optimal solution is desired. The performance of the method for layout optimization of Pipe networks is tested against two benchmark examples in the literature and the results are presented.

  • application of a max min ant system to joint layout and Size optimization of Pipe networks
    Engineering Optimization, 2006
    Co-Authors: Mohammad Hadi Afshar
    Abstract:

    The application of a max–min ant algorithm to the layout and Size optimization of Pipe networks is described in this paper. The formulation conventionally used for the Pipe Size optimization of networks with fixed layout is extended to account for the layout determination of the networks. This is achieved by including new constraints regarding the reliability of the network and modifying some of the constraints of the optimization problem. A deterministic concept of reliability is used in which the number of independent paths from source nodes to each of the demand nodes is considered as a measure of reliability. The method starts with a predefined layout which includes all possible links. The method is capable of designing the layout and Pipe Sizes of water distribution networks of predefined reliability including tree-like and looped networks. It is also shown that a layout optimization of a network followed by Size optimization does not lead to an optimal or a near-optimal solution. This emphaSizes the...

Tiku T. Tanyimboh - One of the best experts on this subject based on the ideXlab platform.

  • Coupled Topology and Pipe Size Optimization of Water Distribution Systems
    Water Resources Management, 2013
    Co-Authors: Salah H. A. Saleh, Tiku T. Tanyimboh
    Abstract:

    This paper describes a new multi-objective evolutionary optimization approach to the simultaneous layout and Pipe Size design of water distribution systems. Pressure-deficient and topologically infeasible solutions are fully incorporated in the genetic algorithm without recourse to constraint violation penalties or tournaments. The proposed approach is demonstrated by solving three benchmark problems taken from the literature. New optimal layouts and/or new feasible solutions that are cheaper than the best solutions in the literature were found for both branched and looped network configurations. Specifically, a new best solution was generated for each of the above-mentioned benchmark problems. In addition, the case of the looped design of a hitherto branched network in the literature was considered. Detailed results are included that show that the proposed approach achieves good solutions efficiently and consistently.

  • Joint layout, Pipe Size and hydraulic reliability optimization of water distribution systems
    Engineering Optimization, 2008
    Co-Authors: Tiku T. Tanyimboh, Y. Setiadi
    Abstract:

    A multicriteria maximum-entropy approach to the joint layout, Pipe Size and reliability optimization of water distribution systems is presented. The capital cost of the system is taken as the principal criterion, and so the trade-offs between cost, entropy, reliability and redundancy are examined sequentially in a large population of optimal solutions. The novelty of the method stems from the use of the maximum-entropy value as a preliminary filter, which screens out a large proportion of the candidate layouts at an early stage of the process before the designs and their reliability values are actually obtained. This technique, which is based on the notion that the entropy is potentially a robust hydraulic reliability measure, contributes greatly to the efficiency of the proposed method. The use of head-dependent modelling for simulating Pipe failure conditions in the reliability calculations also complements the method in locating the Pareto-optimal front. The computational efficiency, robustness, accura...

Andrew Long - One of the best experts on this subject based on the ideXlab platform.

Youssef Tlili - One of the best experts on this subject based on the ideXlab platform.

  • Reliability-Based Pipe Size Computation of On-Demand Irrigation Systems
    Water Resources Management, 2012
    Co-Authors: Nicola Lamaddalena, Roula Khadra, Youssef Tlili
    Abstract:

    The variability of flow regimes in on demand pressurized irrigation systems leads to uncertainty in head at the nodes affecting the system performance, and thus it should be considered when designing and/or rehabilitating water distribution systems. Based on these considerations a new approach for the optimization of on demand pressurized irrigation systems is presented combining the minimization of cost with the maximization of reliability taking into account the stochastic variability of the flows into each section of the network. The new model, Clément and the cumulated random generated discharges model (FAO model) were applied to three pressurized irrigation networks of different dimensions (large, medium and small) operating on demand in Southern Italy. The optimization algorithm used in all the cases is the Labye iterative discontinuous method, a formulation of the dynamic programming. The results of the different models were compared showing that the cost of the optimal network calculated using the new model was reduced by more than 20%, without any significant decrease of the system reliability or reduction of the network capacity.

  • Reliability-Based Pipe Size Computation of On-Demand Irrigation Systems
    Water Resources Management, 2011
    Co-Authors: Nicola Lamaddalena, Roula Khadra, Youssef Tlili
    Abstract:

    The variability of flow regimes in on demand pressurized irrigation systems leads to uncertainty in head at the nodes affecting the system performance, and thus it should be considered when designing and/or rehabilitating water distribution systems. Based on these considerations a new approach for the optimization of on demand pressurized irrigation systems is presented combining the minimization of cost with the maximization of reliability taking into account the stochastic variability of the flows into each section of the network. The new model, Clement and the cumulated random generated discharges model (FAO model) were applied to three pressurized irrigation networks of different dimensions (large, medium and small) operating on demand in Southern Italy. The optimization algorithm used in all the cases is the Labye iterative discontinuous method, a formulation of the dynamic programming. The results of the different models were compared showing that the cost of the optimal network calculated using the new model was reduced by more than 20%, without any significant decrease of the system reliability or reduction of the network capacity.

Saeed Hashemi - One of the best experts on this subject based on the ideXlab platform.