The Experts below are selected from a list of 354 Experts worldwide ranked by ideXlab platform
Massimo Franchini - One of the best experts on this subject based on the ideXlab platform.
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Multiobjective Optimization of Rehabilitation and Leakage Detection Scheduling in Water Distribution Systems
Journal of Water Resources Planning and Management, 2009Co-Authors: Stefano Alvisi, Massimo FranchiniAbstract:This paper presents a procedure for optimal medium-term scheduling (e.g., over a time window of 5 years) of Rehabilitation and leakage detection interventions in a water distribution system given predetermined budget constraints. The decisional variables are the interventions to be scheduled, that is, which Pipes to replace and when (in which year), and where and when (in which zone and year) to carry out leakage detection surveys, while the objectives are to minimize the volumes of water lost and break repair costs. The optimizer used is the NSGA II multiobjective genetic algorithm. It is assumed that the budget allocated for leakage detection and Pipe Rehabilitation (proactive interventions) represents a separate expenditure item from that for the repair of breaks (reactive interventions). In particular, whereas repair costs are subject to minimization, the budget for proactive interventions is allocated on a yearly basis during the scheduling period and a constraint is determined by the fact that the a...
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Multiobjective Optimization of Rehabilitation and Leakage
Journal of Water Resources Planning and Management, 2009Co-Authors: Stefano Alvisi, Massimo FranchiniAbstract:This paper presents a procedure for optimal medium-term scheduling (e.g., over a time window of 5 years) of Rehabilitation and leakage detection interventions in a water distribution system given predetermined budget constraints. The decisional variables are the interventions to be scheduled, that is, which Pipes to replace and when (in which year), and where and when (in which zone and year) to carry out leakage detection surveys, while the objectives are to minimize the volumes of water lost and break repair costs. The optimizer used is the NSGA II multiobjective genetic algorithm. It is assumed that the budget allocated for leakage detection and Pipe Rehabilitation (proactive interventions) represents a separate expenditure item from that for the repair of breaks (reactive interventions). In particular, whereas repair costs are subject to minimization, the budget for proactive interventions is allocated on a yearly basis during the scheduling period and a constraint is determined by the fact that the a...
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Multiobjective Optimization of Rehabilitation and Leakage Detection Scheduling in Water Distribution Systems
Journal of Water Resources Planning and Management, 2009Co-Authors: Stefano Alvisi, Massimo FranchiniAbstract:This paper presents a procedure for optimal medium-term scheduling ͑e.g., over a time window of 5 years͒ of Rehabilitation and leakage detection interventions in a water distribution system given predetermined budget constraints. The decisional variables are the interventions to be scheduled, that is, which Pipes to replace and when ͑in which year͒, and where and when ͑in which zone and year͒ to carry out leakage detection surveys, while the objectives are to minimize the volumes of water lost and break repair costs. The optimizer used is the NSGA II multiobjective genetic algorithm. It is assumed that the budget allocated for leakage detection and Pipe Rehabilitation ͑proactive interventions͒ represents a separate expenditure item from that for the repair of breaks ͑reactive interventions͒. In particular, whereas repair costs are subject to minimization, the budget for proactive interventions is allocated on a yearly basis during the scheduling period and a constraint is determined by the fact that the amounts budgeted must be completely spent, year after year: this reflects the customary practice of water utilities, which strive to spend the entire budget available to them, since any residual amount may not be reallocated to the same expenditure item in the year or years to come. The multiobjective optimization procedure does not produce one optimal solution, but rather the Pareto front of nondominated solutions. Some considerations for identifying a range of solutions within this front, from which to choose the one to apply, are thus discussed. The procedure is applied to a real water distribution system using advanced models to represent the various processes that characterize the problem, namely, leakages as a function of Pipe age and pressure, actual nodal discharges released as a function of head, time series of Pipe breaks, etc. and the results obtained show that the proposed procedure may be a useful decision support tool for scheduling leakage detection campaigns and Rehabilitation interventions.
Florin George Iloaie - One of the best experts on this subject based on the ideXlab platform.
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choosing the optimal technology to rehabilitate the Pipes in water distribution systems using the ahp method
Energy Procedia, 2017Co-Authors: Ioan Așchilean, Ioan Giurca, Gheorghe Badea, George Sebastian Naghiu, Florin George IloaieAbstract:Abstract In this paper the authors intend to solve in a scientific way, using the AHP method, a problem faced by companies in the field of water supply in towns, and choosing the technology of Pipe Rehabilitation in water distribution systems. This paper presents a case study on the selection of the technology for the Rehabilitation of domestic water distribution network in Cluj-Napoca. We used the AHP method in order to rank the priorities regarding the Rehabilitation of water distribution network. Based on the study performed, we recommend using the Slipline method for the Rehabilitation of water distribution Pipes in Cluj-Napoca, Romania. The method presented in this paper may be used for the feasibility studies elaborated for water distribution networks. Also, the AHP method may be correspondingly used for the selection of other types of installations for buildings.
Ioan Așchilean - One of the best experts on this subject based on the ideXlab platform.
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choosing a water distribution Pipe Rehabilitation solution using the analytical network process method
Water, 2018Co-Authors: Ioan Așchilean, Ioan GiurcaAbstract:One of the major challenges faced by water companies around the world is the high level of water losses in distribution networks. This research paper presents a case study on the choice of the best technical solution for the Rehabilitation of the water distribution network Pipelines of Cluj-Napoca City, Romania. The analytical network process (ANP) method was used as the selection method, and calculations were performed using the Super Decisions 2.6.0 software. In the case study, five alternatives were analyzed based on seven criteria. The criteria taken into account in the decision-making included Pipe diameter, Pipe length, specific accomplishment duration, lifespan, pressure losses, price, and installation conditions, while the following methods were considered as Rehabilitation alternatives: Compact Pipe, Slipline, Subline, Swagelining, and Pilot Pipe. Based on the highest global priority, we recommend choosing the Subline alternative as the method of rehabilitating water distribution Pipes from asbestos cement Pipes in the case of Cluj-Napoca City, Romania.
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choosing the optimal technology to rehabilitate the Pipes in water distribution systems using the ahp method
Energy Procedia, 2017Co-Authors: Ioan Așchilean, Ioan Giurca, Gheorghe Badea, George Sebastian Naghiu, Florin George IloaieAbstract:Abstract In this paper the authors intend to solve in a scientific way, using the AHP method, a problem faced by companies in the field of water supply in towns, and choosing the technology of Pipe Rehabilitation in water distribution systems. This paper presents a case study on the selection of the technology for the Rehabilitation of domestic water distribution network in Cluj-Napoca. We used the AHP method in order to rank the priorities regarding the Rehabilitation of water distribution network. Based on the study performed, we recommend using the Slipline method for the Rehabilitation of water distribution Pipes in Cluj-Napoca, Romania. The method presented in this paper may be used for the feasibility studies elaborated for water distribution networks. Also, the AHP method may be correspondingly used for the selection of other types of installations for buildings.
Dragan Savic - One of the best experts on this subject based on the ideXlab platform.
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development of Pipe deterioration models for water distribution systems using epr
Journal of Hydroinformatics, 2008Co-Authors: Luigi Berardi, Orazio Giustolisi, Zoran Kapelan, Dragan SavicAbstract:The economic and social costs of Pipe failures in water and wastewater systems are increasing, putting pressure on utility managers to develop annual replacement plans for critical Pipes that balance investment with expected benefits in a risk-based management context. In addition to the need for a strategy for solving such a multi-objective problem, analysts and water system managers need reliable and robust failure models for assessing network performance. In particular, they are interested in assessing a conduit9s propensity to fail and how to assign criticality to an individual Pipe segment. In this paper, Pipe deterioration is modelled using Evolutionary Polynomial Regression. This data-driven technique yields symbolic formulae that are intuitive and easily understandable by practitioners. The case study involves a water quality zone within a distribution system and entails the collection of historical data to develop network performance indicators. Finally, an approach for incorporating such indicators into a decision support system for Pipe Rehabilitation/replacement planning is introduced and articulated.
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Evolutionary multi-objective optimization of the design and operation of water distribution network: total cost vs. reliability vs. water quality
Journal of Hydroinformatics, 2006Co-Authors: Raziyeh Farmani, Godfrey A. Walters, Dragan SavicAbstract:An expanded Rehabilitation of the hypothetical water distribution network of Anytown, USA is considered. As well as Pipe Rehabilitation decisions, tank sizing, tank siting and pump operation schedules are considered as design variables. Inclusion of pump operation schedules requires consideration of water system operation over the demand pattern period. Design of distribution storage facilities involves solving numerous issues and trade-offs such as locations, levels and volume. This paper investigates the application of multi-objective evolutionary algorithms in the identification of the pay-off characteristic between total cost, reliability and water quality of Anytown9s water distribution system. A new approach is presented for formulation of the model. To provide flexibility, the network must be designed and operated under multiple loading conditions. The cost of the solution includes the capital costs of Pipes and tanks as well as the present value of the energy consumed during a specified period. Optimization tends to reduce costs by reducing the diameter of, or completely eliminating, Pipes, thus leaving the system with insufficient capacity to respond to Pipe breaks or demands that exceed design values without violating required performance levels. Here a resilience index is considered as a second objective to increase the hydraulic reliability and the availability of water during Pipe failures. Considering reliability as one of the objectives in the optimization process will decrease the level of vulnerability for the solutions and therefore will result in robust networks. However, oversized distribution mains and storage tanks will have adverse effects on water age with negative effects on water quality due to low flow velocity and little turnover, respectively. Therefore, another objective in the design and operation of distribution systems with storage facilities is the minimization of residence time, thus minimizing deterioration in water quality, which is directly associated with the age of water. Residence time must include not only the time in tanks but also the travel time before and after the water9s entry into the storage facilities. The residence time of the water in the network is considered as a surrogate measure of water quality. Results are presented for the pay-off characteristics between total cost, reliability and water quality, for 24 h design and five loading conditions.
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Trade-off between Total Cost and Reliability for Anytown Water Distribution Network
Journal of Water Resources Planning and Management, 2005Co-Authors: Raziyeh Farmani, Godfrey A. Walters, Dragan SavicAbstract:This paper investigates the application of multiobjective evolutionary algorithms to the identification of the payoff characteristic between total cost and reliability of a water distribution system using the well-known "Anytown" network as an example. An expanded Rehabilitation problem is considered where the design variables are the Pipe Rehabilitation decisions, tank sizing, tank siting, and pump operation schedules. To provide flexibility, the network is designed and operated under multiple loading conditions. Inclusion of pump operation schedules requires consideration of water system operation over an extended period. The cost of the solution includes the capital costs of Pipes and tanks as well as the present value of the energy consumed during a specified period. Optimization tends to reduce costs by reducing the diameter of, or completely eliminating, some Pipes, thus leaving the system with insufficient capacity to respond to Pipe breaks or demands that exceed design values without violating required performance levels. A resilience index is considered as a second objective to increase the hydraulic reliability and availability of water during Pipe failures. Sensitivity analysis of solutions on the payoff curve generated by twin-objective optimization shows poor performance of these networks under random Pipe failure or a pump being out of service. The minimum surplus head is added as a third objective to overcome the shortcomings of the resilience index. Results are presented for the payoff characteristics between total cost and reliability for 24 h design and five loading conditions.
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Determining maintenance requirements of a water distribution network using whole life costing
Journal of Quality in Maintenance Engineering, 2002Co-Authors: Mark Engelhardt, Godfrey A. Walters, Dragan Savic, Peter Skipworth, Adrian Cashman, Adrian J. SaulAbstract:A whole life costing (WLC) methodology has been developed for determining long term maintenance expenditure requirements for water distribution networks. The methodology utilises an accounting scheme that ties the costs incurred by the operator and other stakeholders to the attributes or performance that drive the costs. It has specifically been derived with the requirements placed by the regulatory regime on the water companies that operate in England and Wales in mind. Expenditure constraints are implied by the regulator through price caps that companies can charge their customers. Appropriate levels of expenditures included as part of the price cap determinations are required by the regulator to be economically robust and tied to the service received by the customers. Therefore, maintenance decisions must reflect more immediate concerns of meeting performance requirements, but must ensure that such levels are sustainable in the long term. The WLC methodology achieves this through an integrated platform that links costs identified within a structured accounting scheme with their performance based drivers commonly modelled based on historical data. Thus, a robust and fully auditable methodology is provided that can address the requirements of all stakeholders. This methodology is the basis for software (WiLCO) that provides decision support in determining appropriate Pipe Rehabilitation and operational strategy and thus expenditure levels over extended time horizons.
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Improved design of “Anytown” distribution network using structured messy genetic algorithms
Urban Water, 1999Co-Authors: Godfrey A. Walters, Driss Halhal, Dragan Savic, Driss OuazarAbstract:Abstract The recently introduced Structured Messy Genetic Algorithm model for optimising water distribution network Rehabilitation is expanded to include not only Pipe Rehabilitation decisions but also pumping installations and storage tanks as variables. The formulation of the model is detailed with two approaches presented for handling the design of storage within the system. The application of the model to the benchmark “Anytown” problem is used as an example of its capabilities, with cheaper designs being produced than any previously published.
John C Matthews - One of the best experts on this subject based on the ideXlab platform.
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environmental impact assessment of the fabrication of Pipe Rehabilitation materials
Journal of Pipeline Systems Engineering and Practice, 2020Co-Authors: Alhossin Alsadi, John C Matthews, Elizabeth MatthewsAbstract:AbstractWith the consistent increase in the global population, sustainable construction has become a trend that will need to be practiced in perpetuity. The three main factors of sustainable constr...
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Analysis of risk management methods used in trenchless renewal decision making
Tunnelling and Underground Space Technology, 2018Co-Authors: Greta Vladeanu, John C MatthewsAbstract:Abstract The substandard condition of wastewater systems in the US, accompanied by the lack of financial resources for renewal are hindering adequate operation and maintenance of deficient sewer systems. Information about current and future Pipe condition, as well as information about the impact of possible Pipe failures are an integral part of an efficient asset management program and can help stakeholders make the best decisions to prioritize Rehabilitation and/or replacement projects. Typically, Pipes in the worst structural conditions are prioritized and budgeted within the capital improvement project planning. To be able to predict future Pipe conditions, many methods have been developed and successfully implemented that incorporate Pipe inspection data to predict the future state of these assets. Additionally, methodologies exist for determining the consequences of Pipe failures economically, socially, and environmentally. These methods have been incorporated into decision support systems (DSS) that help utility managers determine when to rehabilitate or replace their assets. DSS for trenchless Pipe renewal allow utility managers to determine the most suitable method to renew their assets, given known defects in the Pipe. The aim of this paper is to provide a review of risk management methods that allow Pipeline managers to estimate likelihood of failure and quantify consequence of failure of sewer Pipes. Additionally, an updated review of existing DSS for trenchless Pipe Rehabilitation is presented and analyzed. Finally, recommendations are made to improve existing methods to make the risk management process for trenchless Rehabilitation decision making more efficient and practical.
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Studying the Life-cycle Performance of Gravity Sewer Rehabilitation Liners in North America☆
Procedia Engineering, 2016Co-Authors: Raymond L. Sterling, Erez N Allouche, John C Matthews, Shaurav Alam, Wendy Condit, Declan DowneyAbstract:Abstract Pipe Rehabilitation and trenchless replacement technologies have seen a steadily increasing use and represent an increasing proportion of the annual expenditure on operations and maintenance of the water and wastewater infrastructure around the world. Despite the large public investment in use of these technologies, there has been little quantitative evaluation of how these technologies are performing. A retrospective study conducted by the U.S. Environmental Protection Agency collected 25 samples between 2009 and 2013 of in-service gravity sewer liners from 11 cities in North America. Testing of the various liners included thickness, annular gap, ovality, specific gravity, porosity, flexural strength, flexural modulus, tensile strength, tensile modulus, surface hardness, glass transition temperature, Raman spectroscopy, environmental stress crack resistance and Pipe stiffness as appropriate to the liner type and condition. Cured-in-place Pipe (CIPP) liners comprised 18 of the 25 samples. Other liners included were PVC fold-and-form, HDPE deform-reform and sliplining. The samples had seen from 5 years to 34 years in service. A number of areas where the QA/QC of liner installation should improve were noted in the studies but, overall, the liners were in excellent condition and the physical test results indicated that these liners are expected to last their 50-year design life and probably well beyond.
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Pipe Bursting Asbestos Cement Pipe: The Process Is Established but What's Next
Pipelines 2015, 2015Co-Authors: Edward Alan Ambler, John C Matthews, L. Pultz, Ryan StoweAbstract:The City of Casselberry completed its $10.3 million asbestos cement (AC) pre-chlorinated potable water main Pipe bursting project in April of 2014 which replaced approximately 35 miles of AC Pipe. City staff has worked closely with the contractor, engineers and regulators from local and federal government to fully understand the applicability of the National Emissions Standards for Hazardous Air Pollutants (NESHAP) to Pipe bursting of asbestos cement Pipe. The Environmental Protection Agency and industry representatives have recognized the need to understand the potential environmental impacts of AC Pipe Rehabilitation and have tasked the Water Research Foundation and the Battelle Institute with studying the various methods of AC Pipe Rehabilitation. The environmental impacts of Pipe bursting AC Pipe have been analyzed with the Casselberry Water Quality Improvement Project as its pilot project. Results of the WRF study indicate that bursting AC Pipe is more environmentally friendly than removing the existing AC Pipe while providing the option to rehabilitate the existing Pipeline in place. This paper will present the results of WRF Project #4465 while clearly describing how to burst AC Pipelines and meet all existing regulations. This paper describes the challenges and successes of implementing a Pipe bursting project, from field application of Pipe bursting technology to working directly with regulators and rightof-way controllers who may be skeptical about Pipe bursting AC Pipe. A potential path forward through submission of a potential Administrator Approved Alternate to EPA that accepts a streamlined AC Pipe bursting process is also presented.
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A retrospective evaluation of the performance of liner systems used to rehabilitate municipal gravity sewers
Tunnelling and Underground Space Technology, 2015Co-Authors: Shaurav Alam, Erez N Allouche, John C Matthews, Raymond L. Sterling, Wendy Condit, Ari Selvakumar, Jadranka SimicevicAbstract:Abstract This paper provides new results gathered as part of a 6-year project funded by the U.S. Environmental Protection Agency (USEPA) to document the in-service performance of trenchless Pipe Rehabilitation techniques. The results from a pilot study focusing on cured-in-place Pipe (CIPP) Rehabilitation technologies were previously reported and the research program was extended to allow collection of additional CIPP samples and also to extend the study to other Rehabilitation technologies (specifically included in this Phase 2 research were fold-and-form, deform–reform, and sliplining technologies). The establishment of a database to house performance evaluation data for Rehabilitation technologies used in the water and wastewater sectors is also described. The additional retrospective data for CIPP and other Rehabilitation technologies are reported and an overall assessment of CIPP life cycle performance is provided. The examination of CIPP liners with up to 34 years in service and other Rehabilitation technologies with up to 19 years of service has shown that all of the Rehabilitation technologies are showing little evidence of deterioration in service. The test results for 18 CIPP samples from nine cities across North America indicate that properly designed and installed CIPP liners should meet and likely exceed the typical 50-year expected design life. For the fold-and-form, deform–reform, and sliplining technologies, there are only two to three samples per Rehabilitation technology and hence less can be said about overall performance. Nevertheless, all of the samples tested still met the material property requirements at installations after 14–19 years of service. In summary, the results provide an excellent prognosis for the Rehabilitation technologies evaluated.