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1
Akkas, Izzet Saygin. "Reliability Based Water Distribution Network Design." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607830/index.pdf.
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The need of water and the limited sources, force the researchers to find the most economical and feasible solution in the design of a water distribution network. In this study, reliability and optimization of a water distribution network are taken into account together in the design stage of the network. The relationship between reliability of a water distribution network and its cost is examined during the design of a water distribution network. A methodology for deciding the reliability level of the selected design is proposed by examining the reliability-cost relationship. The design alternatives for the case study area are obtained by the aid of a commercially available software WADISO employing partial enumeration optimization technique. The reliability value for each of the design alternative is calculated according to Misirdali (2003)&rsquos adaptation based on the methodology proposed by Bao and Mays (1990) by the aid of a hydraulic network solver program HapMam prepared by Nohutç
u (2002). For purposes of illustration, the skeletonized form of Ankara Water Distribution Network subpressure zone (N8-1) is taken as the case study area. The methodology in this study, covering the relation between the reliability and the cost of a water distribution network and the proposed reliability level can be used in the design of new systems.
2
Keles, Gultekin. "Water Distribution Network Design By Partial Enumeration." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606816/index.pdf.
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Water distribution networks are being designed by traditional methods based on rules-of-thumb and personal experience of the designer. However, since there is no unique solution to any network design, namely there are various combinations of
pipes, pumps, tanks all of which satisfy the same pressure and velocity restrictions, it is most probable that the design performed by traditional techniques is not the optimum one.
This study deals how an optimization technique can be a useful tool for a designer during the design to find a solution. The method used within the study is the partial enumeration technique developed by Gessler. The technique is applied by a
commercially available software, i.e. WADISO SA. The study is focused on discrepancies between a network designed by traditional techniques and the same network designed by partial enumeration method. Attention is given to steps of enumeration, which are basically grouping of pipes, candidate pipe size and price function assignments, to demonstrate that the designers can control all the phases of optimization process. In this respect, special attention is given to price functions to show the effect of them on the result. The study also revealed that the cost of fitting materials cannot be included in the price function although it may have significant
effect in a system composed of closely located junctions.
The results obtained from this study are useful to show that although optimization methods do not provide a definite solutionpartial enumeration method can assist designers to select the optimum system combination.
3
Gupta, Gagan. "Monitoring Water Distribution Network using Machine Learning." Thesis, KTH, Nätverk och systemteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-221832.
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Water is an important natural resource. It is supplied to our home by water distribution network thatis owned and maintained by water utility companies. Around one third of water utilities across the globereport a loss of 40% of clean water due to leakage. The increase in pumping, treatment and operationalcosts are pushing water utilities to combat water loss by developing methods to detect, locate, and xleaks. However, traditional pipeline leakage detection methods require periodical inspection with humaninvolvement, which makes it slow and inecient for leakage detection in a timely manner. An alternativeis on-line, continuous, real-time monitoring of the network facilitating early detection and localization ofthese leakages. This thesis aims to nd such an alternative using various Machine Learning techniques.For a water distribution network, a novel algorithm is proposed based on the concept of dominantnodes from graph theory. The algorithm nds the number of sensors needed and their correspondinglocations in the network. The network is then sub-divided into several leakage zones, which serves as abasis for leak localization in the network. Thereafter, leakages are simulated in the network virtually,using hydraulic simulation software. The obtained time series pressure data from the sensor nodes ispre-processed using one-dimensional wavelet series decomposition by using daubechies wavelet to extractfeatures from the data. It is proposed to use this feature extraction procedure at every sensor nodelocally, which reduces the transmitted data to the central hub over the cloud thereby reducing the energyconsumption for the IoT sensor in real world.For water leakage detection and localization, a procedure for obtaining training data is proposed,which serves as a basis for recognition of patterns and regularities in the data using supervised Machinelearning techniques such as Logistic Regression, Support Vector Machine, and Articial Neural Network.Furthermore, ensemble of these trained model is used to build a better model for leakage detection andits localization. In addition, Random Forest algorithm is trained and its performance is compared tothe obtained ensemble of earlier models. Also, leak size estimation is performed using Support VectorRegression algorithm.It is observed that the sensor node placement using proposed algorithm provides a better leakage localizationresolution than random deployment of sensor. Furthermore, it is found that leak size estimationusing Support Vector Regression algorithm provides a reasonable accuracy. Also, it is noticed that RandomForest algorithm performs better than the ensemble model except for the low leakage scenario. Thus,it is concluded to estimate the leak size rst, based on this estimation for small leakage case ensemblemodels can be applied while for large leakage case only Random Forest can be used.Vatten ar en viktig naturresurs. Den levereras till vart hem via vattendistributionsnatet, som ags och underhalls av vattenforetag. Omkring en tredjedel av vattenforetagen over hela varlden rapporterar en forlustpa 40 % rent vatten pa grund av lackage. Okningen av pumpnings-, behandlings- och driftskostnader drivervattenforsorjningen till att bekampa vattenforluster genom att utveckla metoder for att upptacka, lokaliseraoch xa lackor. Emellertid kraver traditionella pipeline-detekteringsmetoder periodisk inspektion medstor skala mansklig inblandning, vilket gor det langsamt och ineektivt for lackage-detektion i tid. Ettalternativ ar on-line, kontinuerlig, realtidsovervakning av natverket som underlattar tidig detektering ochlokalisering av dessa lackage. Avhandlingen syftar till att hitta ett sadant alternativ med hjalp av olikamaskinlasningstekniker.For ett vattendistributionsnat foreslas en ny algoritm baserad pa begreppet dominerande noder frangrafteori. Algoritmen nner ut hur manga sensorer som behovs och deras motsvarande platser i natverket.Natverket delas sedan in i era lackagezoner, som utgor grunden for lackageplacering i natverket. Dareftersimuleras lackage i natverket praktiskt taget med hjalp av hydraulisk simuleringsprogramvara. Denerhallna tidsserie-tryckdatan fran sensornoderna forbehandlas med anvandning av endimensionell waveletseriebrytning genom att anvanda Daubechies Wavelet for att extrahera sardrag fran data. Det foreslas attanvanda detta extraktionsprocedur vid varje sensornod lokalt vilket minskar overford data till det centralanavet over molnet och darigenom minskar energiforbrukningen for IoT-sensorn i verkliga varlden.For upptackt och lokalisering av vattenlackage foreslas ett forfarande for erhallande av traningsdata,som utgor grunden for erkannande av monster och regelbundenhet i data som anvander overvakade maskininlarningstekniker, sasom logistik regression, stodvektormaskin och konstgjort neuralt natverk. Dessutomanvands ensemble av dessa tranad modeller for att bygga en battre modell for lackagespecikationoch lokalisering. Utover det ar Random Forest-algoritmen tranad och dess prestanda jamfordes med deterhallna ensemblet av tidigare modeller. Ocksa utmatning av lackstorlek utfors med hjalp av SupportVector Regression-algoritmen.Det observeras att sensorns nodplacering med anvandning av den foreslagna algoritmen ger en battrelackage-lokaliseringsupplosning an slumpmassig utplacering av sensorn. Vidare konstateras att lackstorleksuppskattningmed hjalp av supportvektorregressionsalgoritmen ger en rimlig noggrannhet. Det noterasocksa att Random Forest-algoritmen fungerar battre an ensemblemodellen med undantag for lag lackagescenario. Slutligen innebar detta att man uppskattar lackagestorleken forst. Baserat pa denna uppskattningfor sma lackagefall, kan ensemblemodeller appliceras medan for stort lackagefall kan endast RandomForest anvandas.
4
Jakubovics, Nicholas S. "Biofilms in the potable water distribution network." Thesis, University of Warwick, 1998. http://wrap.warwick.ac.uk/36980/.
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The roles of vegetative dormancy and attachment to surfaces in the survival and growth of bacteria in potable water systems were investigated. Species present in the water were identified following isolation or direct observation of static batch enrichment cultures. Using the latter approach, many prosthecate and other stalked bacteria were found. Prosthecate bacteria undergo bi- or poly-phasic life cycles involving asymmetric division to produce reproductive cells and dormant swarmer cells and their presence in tap water supports the theory that vegetative dormancy is an important survival mechanism in this environment. A continuous flow model was established to analyse the metabolic activity of planktonic and attached bacteria in potable water. A physiological dye, 5-cyano-2,3-ditolyl tetrazolium chloride (CTC), was shown to stain active cells specifically in batch cultures of a Sphingomonas sp. and Caulobacter crescentus. Unsuccessful attempts were made to identify cellular proteins of Sphingomonas sp. cells that were specific to the attached or planktonic phenotype. By comparing the total bacterial counts in potable water with the total viable counts it was shown that a large proportion of the microflora was not cultivable on heterotrophic media. However, a proportion of these cells became culturable following enrichment with peptone. After ceasing the exogenous nutrient addition cellular aggregation occurred, presumably reflecting physiological changes in response to nutrient depletion. No clear trend in the activity of attached cells during biofilm development was detected. However, firmly attached cells were buffered against changes in the chemistry of the water. Growth within biofilms and release into the water column elevated the concentration of bacteria in the water. Attached cells were resistant to 0.3 mg free chlorine 1-1 added for 3 hrs, although this did weaken the architecture of the biofilm. Long term biofilms (one year-old) were almost devoid of bacteria - an observation that could not be adequately explained.
5
Ar, Kerem. "Calibration Of Water Distribution Networks." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12613934/index.pdf.
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Water distribution network models are used for different purposes. In this study, a model, used for daily operational issues is concerned. Models results should be consistent with actual conditions for sound decisions during operational studies. Adjusting model parameters according to site measurements in order to fit the model to obtain realistic results is known as calibration. Researchers have carried out numerous studies on calibration and developed various methods. In this study, an actual network (N8.3 Pressure Zone, Ankara) has been calibrated by two classical methods developed by Walski (1983) and Bhave (1988). The network parameter calibrated in this study is Hazen-Williams roughness coefficient, C-factor, and other parameters have been lumped in the C-factor. Results of the analysis showed that, C-factors have been found in a wide range.
6
Memarian, Neda. "Resilience of Water Distribution Networks." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
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Resilience is widely interpreted as the capacity of a system to resist (preparation phase), absorb and withstand (responding phase), and rapidly recover from (restoration phase) exceptional conditions. During this study, a mixed variety of calculations were assessed in order to find the best solution for determination of resilience and reliability of a simple network. Then, Todini’s formula and failure index was applied to estimate reliability of system in different scenarios as constant demands in period of 24 hours, constant demands in period of 72 hours when tank will be empty (failure of tank), variable demands in period of 24 hours. At first hydraulic simulation of those scenarios was done by EPANET and validated by MATLAB-TOOLKIT. Then, Resilience index (RI), Failure Index (FI) and reliability (R) of system were measured. Finally, an optimization procedure was done to make a water distribution network with highest resilience and lowest failure probability. All these procedures have been applied on a real network as WDS of Modena. It concluded that this method can be used for every water system without considering the type of failure. As a result, first scenario has a constant decreased and increased trend of RI and FI respectively because of diminishing of water level in tank. During second scenario, there is significant change after the tank will be empty (or it is broke). Third scenario is more like a real network with variable demand during a day. It was concluded that there is a minimum resilience parameter during day when a peak time of water demand expected. It can be justified that the reservoir and pump system had to sustain more pressure to satisfy the demands of junctions. Maximum resilience is related to night during a day with less demands and providing water by tank to other junctions. This modelling could be useful to optimize the dimensions and features of instruments to increase availability and reliability of system.
7
Wallen, Anna Rebecca. "Water distribution network performance optimisation by layout refinement." Thesis, Brunel University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.429006.
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Gabrys, Bogdan. "Neural network based decision support : modelling and simulation of water distribution networks." Thesis, Nottingham Trent University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387534.
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9
Apaydin, Oncu. "Automated Calibration Of Water Distribution Networks." Master's thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615692/index.pdf.
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Water distribution network models are widely used for various purposes such as long-range planning, design, operation and water quality management. Before these models are used for a specific study, they should be calibrated by adjusting model parameters such as pipe roughness values and nodal demands so that models can yield compatible results with site observations (basically, pressure readings). Many methods have been developed to calibrate water distribution networks. In this study, Darwin Calibrator, a computer software that uses genetic algorithm, is used to calibrate N8.3 pressure zone model of Ankara water distribution networkin this case study the network is calibrated on the basis of roughness parameter, Hazen Williams coefficient for the sake of simplicity. It is understood that there are various parameters that contribute to the uncertainties in water distribution network modelling and the calibration process. Besides, computer software&rsquo
s are valuable tools to solve water distribution network problems and to calibrate network models in an accurate and fast way using automated calibration technique. Furthermore, there are many important aspects that should be considered during automated calibration such as pipe roughness grouping. In this study, influence of flow velocity on pipe roughness grouping is examined. Roughness coefficients of pipes have been estimated in the range of 70-140.
10
Axworthy, David H. "Water distribution network modelling, from steady state to waterhammer." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ27600.pdf.
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11
Sert, Caglayan. "Booster Disinfection In Water Distribution Networks." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/2/12610755/index.pdf.
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Disinfection of the municipal water systems is mostly achieved by means of chlorine
addition at water treatment plants known as sources. Thus, there should be an adequate
chlorine concentration at the source for an effective disinfection throughout the system
by considering upper and lower limits of disinfectant. However, since the disinfectants
are reactive and decays through the system, chlorine added at the source may not
be enough to maintain desired disinfectant residuals which may lead to water quality
problems in the water distribution system. Moreover, the disinfectants such as chlorine
has also an effect to be carcinogen due to formation of disinfectant by-products. Thus,
the system should balance the amount of disinfectant supplied while minimizing the
health risk. In such a case, it is recommended that one or more booster disinfection
stations can be located throughout the system. Such a method can provide more uniform
distribution of the chlorine concentration while reducing the amount of the disinfectant
used. In this thesis, optimum scheduling, and injection rates of the booster disinfection
stations have been searched. The objective is to minimize the injected mass dosage
rate subjected to the provision of adequate and more uniform residual concentration in
the network. Determination of variable network hydraulics and chlorine concentrations
is held out by EPANET network simulation sofware. A C++ code was developed to
interface with EPANET by means of the EPANET Programmer's Toolkit for linear optimization of the disinfectant mass dosage rate applied to the network.
12
Coelho, Sergio Carvalho de Matos Teixeira. "Performance assessment in water supply and distribution." Thesis, Heriot-Watt University, 1996. http://hdl.handle.net/10399/1297.
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13
De, Schaetzen Werner. "Optimal calibration and sampling design for hydraulic network models." Thesis, University of Exeter, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322278.
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14
Ung, Hervé. "Quasi real-time model for security of water distribution network." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0015/document.
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Le but de cette thèse est de modéliser la propagation d’un contaminant au sein d’un réseau d’eau potable muni de capteurs temps réel. Elle comporte les trois axes de développement suivant: la résolution des équations de transport, celle du problème d’identification des sources de contamination et le placement des capteurs.Le transport d’un produit chimique est modélisé dans un réseau d’eau potable par l’équation de transport réaction 1-D avec l’hypothèse de mélange parfait aux noeuds. Il est proposé d’améliorer sa prédiction par l’ajout d’un modèle de mélange imparfait aux jonctions double T et d’un modèle de dispersion prenant en compte un profil de vitesse 3-D et la diffusion radiale. Le premier modèle est créé à l’aide d’un plan d’expériences avec triangulation de Delaunay, de simulations CFD, et de la méthode d’interpolation krigeage. Le second utilise les équations adjointes du problème de transport avec l’ajout de particules évoluant à l’aide d’une marche aléatoire, cette dernière modélisant la diffusion radiale dans la surface droite du tuyau.Le problème d’identification des sources consiste, à l’aide de réponses positives ou négatives à la contamination des noeuds capteurs, à trouver l’origine, le temps d’injection et la durée de la contamination. La résolution de ce problème inverse est faite par la résolution des équations de transport adjointes par formulation backtracking. La méthode donne la liste des sources potentielles ainsi que le classement de celles-ci selon leur probabilité d’être la vraie source de contamination. Elle s’exprime en fonction de combien, en pourcentage, cette source potentielle peut expliquer les réponses positives aux capteurs.Le placement des capteurs est optimisé pour l’identification des sources. L’objectif est la maximisation du potentiel de détection de la véritable source de contamination. Deux résolutions sont testées. La première utilise un algorithme glouton combiné à une méthode de Monte Carlo.La seconde utilise une méthode de recherche locale sur graphe.Finalement les méthodes sont appliquées à un cas test réel avec dans l’ordre : le placement des capteurs, l’identification de la source de contamination et l’estimation de sa propagationThe aim of this thesis is to model the propagation of a contaminant inside a water distribution network equipped with real time sensors. There are three research directions: the solving of the transport equations, the source identification and the sensor placement. Classical model for transport of a chemical product in a water distribution network isusing 1D-advection-reaction equations with the hypothesis of perfect mixing at junctions. It isproposed to improve the predictions by adding a model of imperfect mixing at double T-junctions and by considering dispersion effect in pipes which takes into account a 3-D velocity profile. The first enhancement is created with the help of a design of experiment based on the Delaunay triangulation, CFD simulations and the interpolation method Kriging. The second one uses the adjoint formulation of the transport equations applied with an algorithm of particle backtracking and a random walk, which models the radial diffusion in the cross-section of a pipe.The source identification problem consists in finding the contamination origin, itsinjection time and its duration from positive and negative responses given by the sensors. The solution to this inverse problem is computed by solving the adjoint transport equations with a backtracking formulation. The method gives a list of potential sources and the ranking of thosemore likely to be the real sources of contamination. It is function of how much, in percentage, they can explain the positive responses of the sensors.The sensor placement is chosen in order to maximize the ranking of the real source of contamination among the potential sources. Two solutions are proposed. The first one uses agreedy algorithm combined with a Monte Carlo method. The second one uses a local search method on graphs. Finally the methods are applied to a real test case in the following order: the sensor placement, the source identification and the estimation of the contamination propagation
15
Kahler, Jens. "Optimal sizing and operational scheduling of water distribution network components." Thesis, De Montfort University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.433258.
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Tokajian, Sima Toros. "Regrowth of bacteria and their genotypic identification in drinking water in Lebanon." Thesis, University of Newcastle Upon Tyne, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270989.
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LI, ZHIWEI. "NETWORK WATER QUALITY MODELING WITH STOCHASTIC WATER DEMANDS AND MASS DISPERSION." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1147989825.
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Kleiner, Yehuda. "Water distribution network rehabilitation, selection and scheduling of pipe rehabilitation alternatives." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ27979.pdf.
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19
Atkinson, Stuart. "A futures approach to water distribution and sewer network (re)design." Thesis, University of Exeter, 2013. http://hdl.handle.net/10871/10730.
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When designing urban water systems (i.e. water distribution and sewer systems) it is imperative that uncertainty is taken into consideration. However, this is a challenging problem due to the inherent uncertainty associated with both system loading requirements and the potential for physical components failure. It is therefore desirable to improve the reliability of each system in order to account for these uncertainties. Although it is possible to directly evaluate the reliability of a water distribution systems (WDS) (using reliability measures), the calculation processes involved are computationally intensive and therefore unsuitable for some state-of-the-art, iterative design approaches (such as optimisation). Consequently, interest has recently grown in the use of reliability indicators, which are simpler and faster to evaluate than conventional direct reliability methods. In this thesis, a novel measure (the RUF) is developed to quantify reliability in urban water systems with a view to enhance their robustness under a range of future scenarios (Policy Reform, Market Forces, Fortress World and New-Sustainability Paradigm). The considered four future scenarios were synthesized in the EPSRC supported multidisciplinary 4 year project: Urban Futures. Each investigated urban future scenario is characterised by a distinct household water demand and local demand distribution (emerging due to different urban forms evolving in future scenarios). In order to assess the impact of urban futures, RUF has been incorporated into Urban Water System (UWS) dynamic simulations for both WDSs and Foul Sewer Systems (FSSs) using open source codes of EPANET and SWMM. Additionally, in order to overcome extensive computational effort, resulting from the use of traditional reliability measures, a new holistic reliability indicator, the hydraulic power entropy (IHPE) has been developed and compared to existing reliability indicators. Additionally, the relationship between the new reliability indicator and the above mentioned RUF reliability measure is investigated. Results suggest that the magnitude of the IHPE in network solutions provides a holistic indication of the hydraulic performance and reliability for a WDS. However, the performance of optimal solutions under some Urban Futures indicates that additional design interventions are required in order to achieve desired future operation. This thesis also proposes a new holistic foul sewer system (FSS) reliability indicator (the IFSR). The IFSR represents sewer performance as a function of excess pipe capacity (in terms of available increase and also decrease in inflow). The indicator has been tested for two case studies (i.e. different sewer network layouts). Results suggest that the magnitude of IFSR has positive correlations with a number of identified key performance indicators (i.e. relating to capacity, velocity, blockages). Finally, an Integrated Design Approach (IDA) has been developed in order to assess the implications of applying design interventions on both a WDS and downstream FSS. The approach holistically considers present and future operation of each interconnected system. The approach was subsequently demonstrated using two proposed design interventions. Results suggest that, for the considered design interventions, there is trade-off between the simultaneous improvement of both WDS and FSS operation and reliability.
20
Bullene, Rachel. "A Case Study of Network Design for Middle East Water Distribution." VCU Scholars Compass, 2010. http://scholarscompass.vcu.edu/etd/2260.
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The Middle Eastern region encompassing Israel, Jordan, and the Palestinian Territories (West Bank and Gaza) is an arid region with fast growing populations. Adequate and equitable access to water for all the people of the region is crucial to the future of Middle East peace. However, the current water distribution system not only fails to provide an adequate and equitable allocation of water, but also results adverse impacts on the environment. This project involves building a mathematical model to aid decision-makers in designing an optimal water distribution network. A new method for incorporating uncertainty in optimization that is based on Bayesian simulation of posterior predictive distributions is used to represent uncertainty in demands and costs. The output of the model is a most-probable least-cost modication to the existing water distribution infrastructure. Additionally, the model output includes the probability that a network component (new desalination plant, new pipe, new canal) is part of a least-cost installation.
21
Rogalski, Richard Byron. "Mathematical and artificial neural network models for simulation and optimization of chlorine residuals in water distribution systems." access full-text online access from Digital Dissertation Consortium, 2002. http://libweb.cityu.edu.hk/cgi-bin/er/db/ddcdiss.pl?NQ77034.
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Andrade-Rodriguez, Manuel Alejandro. "Computationally Intensive Design of Water Distribution Systems." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/301704.
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The burdensome capital cost of urban water distribution systems demands the use of efficient optimization methods capable of finding a relatively inexpensive design that guarantees a minimum functionality under all conditions of operation. The combinatorial and nonlinear nature of the optimization problem involved accepts no definitive method of solution. Adaptive search methods are well fitted for this type of problem (to which more formal methods cannot be applied), but their computational requirements demand the development and implementation of additional heuristics to find a satisfactory solution. This work seeks to employ adaptive search methods to enhance the search process used to find the optimal design of any water distribution system. A first study presented here introduces post-optimization heuristics that analyze the best design obtained by a genetic algorithm--arguably the most popular adaptive search method--and perform an ordered local search to maximize further cost savings. When used to analyze the best design found by a genetic algorithm, the proposed post-optimization heuristics method successfully achieved additional cost savings that the genetic algorithm failed to detect after an exhaustive search. The second study herein explores various ways to improve artificial neural networks employed as fast estimators of computationally intensive constraints. The study presents a new methodology for generating any large set of water supply networks to be used for the training of artificial neural networks. This dataset incorporates several distribution networks in the vicinity of the search space in which the genetic algorithm is expected to focus its search. The incorporation of these networks improved the accuracy of artificial neural networks trained with such a dataset. These neural networks consistently showed a lower margin of error than their counterparts trained with conventional training datasets populated by randomly generated distribution networks.
23
Hailer, Angelika Christina. "Verification of branch and bound algorithms applied to water distribution network design." Berlin Logos-Verl, 2006. http://deposit.d-nb.de/cgi-bin/dokserv?id=2844475&prov=M&dok_var=1&dok_ext=htm.
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McClymont, Kent. "Multi-objective hyper-heuristics and their application to water distribution network design." Thesis, University of Exeter, 2012. http://hdl.handle.net/10871/8542.
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Hyper-heuristics is a new field of optimisation which has recently emerged and is receiving growing exposure in the research community and literature. Hyper-heuristics are optimisation methods which are designed with a high level of abstraction from any one specific problem or class of problems and therefore are more generally applicable than specialised meta-heuristic and heuristic methods. Instead of being designed to solve a specific real-world problem, hyper-heuristics are designed to solve the problem of heuristic generation and selection. As such, hyper-heuristics can be thought of as methods for optimising the operations of an optimisation process which finds good solutions to a problem as a by-product. This approach has been shown to be very effective and in some cases provides improvement in search performance as well as reducing the burden associated with tailoring meta-heuristics which is often required when solving new problems. In this thesis, the hypothesis that hyper-heuristics can be competitively applied to real-world multi-objective optimisation problems such as the water distribution design problem is tested. Although many single-objective hyper-heuristics have been proposed in the literature, only a few multi-objective methods have been proposed. This thesis explores two different novel multi-objective hyper-heuristics: one designed for generating new specialised heuristics; and one designed for solving the online selection of heuristics. Firstly, the behaviour of a set of heuristics is explored to create a base understanding of different heuristic behavioural traits in order to better understand the hyper-heuristic behaviours and dynamics later in the study. Both approaches are tested on a range of benchmark optimisation problems and finally applied to real-world instances of the water distribution network design problem where the selective hyper-heuristics is demonstrated as being very effective at solving this difficult problem. Furthermore, the thesis demonstrates how heuristic selection can be improved by incorporating a greater level of information about heuristic performance, namely the historical joint performance of different heuristics, and shows that exploiting this sequencing information in heuristic selection can produce highly competitive results.
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Smith, Ernest Price. "An optimal replacement-design model for a reliable water distribution network system." Diss., Virginia Tech, 1994. http://hdl.handle.net/10919/37455.
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Rana, SM Masud. "Contaminant Spread Forecasting and Sampling Location Identification in a Water Distribution Network." University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1383909255.
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Christensen, Ryan T. "Age Effects on Iron-Based Pipes in Water Distribution Systems." DigitalCommons@USU, 2009. https://digitalcommons.usu.edu/etd/505.
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Pipes in water distribution systems may change as they age. The accumulation of corrosion byproducts and suspended particles on the inside wall of aged pipes can increase pipe roughness and reduce pipe diameter. To quantify the hydraulic effects of irregular accumulation on the pipe walls, eleven aged pipes ranging in diameter from 0.020-m (0.75-in) to 0.100-m (4-in) and with varying degrees of turberculation were located and subjected to laboratory testing. The laboratory test results were used to determine a relationship between pipe diameter reduction and Hazen-Williams C. This relationship, combined with a manipulation of the Hazen-Williams equation, provided a simple and direct method for correcting the diameters of aged pipes in distribution models. Using EPANET 2, the importance of correcting pipe diameters when modeling water distribution systems containing aged pipes was investigated. Correcting the pipe diameters in the sample network reduced the modeled water age by up to 10% and changed the pattern of fluctuating water age that occurred as waters with different sources moved through the pipe network. In addition, two of the aforementioned aged pipes with diameters of 0.025-m (1-in) and 0.050-m (2-in) were modeled using Reynolds-Averaged Navier-Stokes (RANS) turbulence modeling. Flow was computed at Reynolds numbers ranging from 6700 to 31,000 using three turbulence models including a 4-equation v2-f model, and 2-equation realizable k-e; and k-ω models. In comparing the RANS results to the laboratory testing, the v2-f model was found to be most accurate, producing Darcy-Weisbach friction factors from 5% higher to 15% lower than laboratory-obtained values. The capability of RANS modeling to provide a detailed characterization of the flow in aged pipes was demonstrated. Large eddy simulation (LES) was also performed on a single 0.050-m (2-in) pipe at a Reynolds number of 6800. The Darcy-Weisbach friction factor calculated using LES was 20% less than obtained from experimental tests. Roughness elements smaller than the grid scale and deficiencies in the subgrid-scale model at modeling the complex three-dimensional flow structures due to the irregular pipe boundary were identified as likely sources of error. Even so, the utility of LES for describing complex flows was established.
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Mounce, Stephen Robert. "A hybrid neural network fuzzy rule-based system applied to leak detection in water pipeline distribution networks." Thesis, University of Bradford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.695062.
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Chilaka, Neelesh. "Applications of water network tool for resilience (WNTR) for metrics and repair strategies of water distribution systems." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/24196/.
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Drinking water systems will always face multiple challenges with respective to aging infrastructure, concerns related to water quality, uncertainty in supply and demand, disruptive events like environmental urgencies, natural disasters, and cyber and terrorist attacks. All of the above-mentioned incidents have the potential to disrupt a large part of a water system or the whole water distribution system either causing the damage to vital parts of infrastructure, affecting the human health, and interrupting service to consumers.Urban or metropolitan communities have experienced loss of infrastructure or its primary functionality in the corollary of the disasters. The coincidence of earthquakes and densely populated cities shall create the potential for increased direct and indirect consequences of seismic events with respective to all infrastructure elements would be at halt until the recovery time they need for full recovery.
The resilience of all the communities to disasters is a component of the execution of infrastructure and their functionality is to be analysed. Water supply networks in the corollary of disasters offer primary assistance to enable, safeguard and improve the conditions for time being. Any interruption in these frameworks will cause inconvenience and challenges for the disrupted network community. Providing enough water at acceptable levels of service in disasters is significant.
The resilience metrics must be determined for the better outcome of the analysis for a better analogy of the work being done for the research. The resilience of the water supply network would be indeterminable accurately since the real- world parameters change from time to time. This dissertation would be using a Python based tool which is Water Network tool for the resilience metrics determination of the water supply network.
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Basaglia, Irene. "Complex networks theory for water distribution networks modelling and resilience assessment. An explorative analysis." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/22858/.
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Il tema della sostenibilità e del conseguente utilizzo di nuove tecniche per la gestione delle risorse idriche è da sempre molto complesso. La digitalizzazione e l'impiego di nuove tecnologie in campo idrico ha ridotto sia i costi che le tempistiche di molteplici processi. Un valido esempio è costituito dalla modellazione surrogata: Il tema centrale della tesi ha come scopo la
costruzione di un modello surrogato di rete di distribuzione idrica utilizzando i principi di Complex Network Theory. In particolare, per condurre questo tipo di studio è stato scelto di analizzare da un punto di vista interdisciplinare i concetti di robustezza e di resilienza ai malfunzionamenti. Le reti di distribuzione idrica possono essere facilmente assimilabili alle reti complesse presenti nella teoria dei grafi. Gli elementi strutturali delle reti idriche sono convertiti nell'equivalente grafo complesso costituito da archi e nodi. Al fine di indagare una possibile correlazione tra le reti di entrambe le discipline, sono state eseguite una serie di simulazioni idriche e valutazioni strutturali calibrando i modelli in base alle euristiche proposte in letteratura. Gli esperimenti eseguiti valutano l'effetto "small world" e altre misure per l'analisi di reti presenti nella teoria dei grafi in relazione all'intensità e alla durata dei malfunzionamenti.
Dai risultati è stata riscontrata una correlazione inversa tra la proprietà di "small world" e l'indice di durata dei malfunzionamenti. In aggiunta, i risultati ottenuti evidenziano una tendenza generale alla correlazione, sia diretta che indiretta. Un ulteriore evidenza emersa dall'analisi è la doppia correlazione presente tra altezza dei nodi, durata dei malfunzionamenti e indice di centralità per vicinanza.
Questo lavoro può dunque aiutare nell'individuazione di parametri più puntuali e adeguati suggerendo nuove vie e tecniche per una ancora più corretta creazione di modelli surrogati tramite tecniche di Complex Network.
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Koker, Ezgi. "Chance Constrained Optimization Of Booster Disinfection In Water Distribution Networks." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613640/index.pdf.
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Quality of municipal water is sustained by addition of disinfectant, generally chlorine, to the water distribution network. Because of health problems, chlorine concentration in the network is limited between maximum and minimum limits. Cancerogenic disinfectant by-products start to occur at high concentrations so it is desired to have minimum amount of chlorine without violating the limit. In addition to the health issues, minimum injection amount is favorable concerning cost. Hence, an optimization model is necessary which covers all of these considerations. However, there are uncertain factors as chlorine is reactive and decays both over time and space. Thus, probabilistic approach is necessary to obtain reliable and realistic results from the model. In this study, a linear programming model is developed for the chance constrained optimization of the water distribution network. The objective is to obtain minimum amount of injection mass subjected to maintaining more uniformly distributed chlorine concentrations within the limits while considering the randomness of chlorine concentration by probability distributions. Network hydraulics and chlorine concentration computations are done by the network simulation software, EPANET.
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Totlani, Rajiv. "Enhanced lower bounds and an algorithm for a water distribution network design model." Thesis, This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-08292008-063331/.
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Lindley, Trevor Ray. "A Framework to Protect Water Distribution Systems Against Potential Intrusions." University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin990722657.
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Graybeal, Dale Kevin. "Evaluation of water distribution system monitoring using a combined simulation-optimization approach." Thesis, This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-01312009-063527/.
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KHANAL, NABIN. "GENERALIZED SENSITIVITY ANALYSIS OF WATER DISTRIBUTION SYSTEM VULNERABILITY TO DELIBERATE INTRUSIONS." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1123791754.
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Rong, Du. "Wireless Sensor Networks in Smart Cities : The Monitoring of Water Distribution Networks Case." Licentiate thesis, KTH, Reglerteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-185453.
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The development of wireless sensor networks (WSNs) is making it possible to monitor our cities. Due to the small size of the sensor nodes, and their capabilities of transmitting data remotely, they can be deployed at locations that are not easy or impossible to access, such as the pipelines of water distribution networks (WDNs), which plays an important role in protecting environment and securing public health. The design of WSNs for WDNs faces major challenges. Generally, WSNs are resource-limited because most of the sensor nodes are battery powered. Thus, their resource allocation has to be carefully controlled. The thesis considers two prominent problems that occur when designing WSNs for WDNs: scheduling the sensing of the nodes of static WSNs, and sensor placement for mobile WSNs. These studies are reported in the thesis from three published or submitted papers. In the first paper, the scheduling of sleep/sensing for each sensor node is considered to maximize the whole WSNs lifetime while guaranteeing a monitoring performance constraint. The problem is transformed into an energy balancing problem, and solved by a dynamic programming based algorithm. It is proved that this algorithm finds one of the optimal solutions for the energy balancing problem. In the second paper, the question of how the energy balancing problem approximates the original scheduling problem is addressed. It is shown that even though these two problems are not equivalent, the gap of them is small enough. Thus, the proposed algorithm for the energy balancing problem can find a good approximation solution for the original scheduling problem. The second part of the thesis considers the use of mobile sensor nodes. Here, the limited resource is the number of available such mobile nodes. To maximize the monitoring coverage in terms of population, an optimization problem for determining the releasing locations for the mobile sensor nodes is formulated. An approximate solution algorithm based on submodular maximization is proposed and its performance is investigated. Beside WDNs, WSN applications for smart cities share a common characteristic: the area to monitor usually has a network structure. Therefore, the studies of this thesis can be potentially generalized for several IoT scenarios.QC 20160419
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Akdogan, Tevfik. "Design Of Water Distribution System By Optimization Using Reliability Considerations." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606082/index.pdf.
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ABSTRACT
DESIGN OF WATER DISTRIBUTION SYSTEM BY OPTIMIZATION USING RELIABILITY CONSIDERATIONS
Akdogan, Tevfik
Department of Civil Engineering
Supervisor : Assoc. Prof. Dr. Nuri Merzi
April 2005, 91 pages
In spite of a wide research, design of water distribution networks are not realized using optimization techniques. One reason for this fact is, design of water distribution networks is evaluated, mostly, as a least-cost optimization problem where pipe diameters being the only decision variables. The other motivation for preferring the traditional modeling practice is that, existing optimization algorithms are not presented to the user as friendly as it should be.
In fact, water distribution systems are very complex systems such that it is not easy to obtain least-cost design systems considering other constraints such as reliability, in addition to classical constraints related to hydraulic feasibility, satisfaction of nodal demands and requirement of nodal pressures. This study presents a user-friendly package concerning the design of water distribution networks by optimization using reliability considerationsthis works employs the algorithm proposed by Goulter and Coals (1986). At the end, a skeletonized network design is offered
various costs are estimated in regard to the degree of reliability.
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Tabesh, Massoud. "Implications of the pressure dependency of outflows of data management, mathematical modelling and reliability assessment of water distribution systems." Thesis, University of Liverpool, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314120.
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Gencoglu, Gencer. "Developing A Methodology For The Design Of Water Distribution Networks Using Genetic Algorithm." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608208/index.pdf.
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The realization of planning, design, construction, operation and maintenance of water supply systems pictures one of the largest infrastructure projects of municipalitieswater distribution networks should be designed very meticulously. Genetic algorithm is an optimization method that is based on natural evolution and is used for the optimization of water distribution networks. Genetic algorithm is comprised of operators and the operators affect the performance of the algorithm. Although these operators are related with parameters, not much attention has been given for the determination of these parameters for this specific field of water distribution networks. This study represents a novel methodology, which investigates the parameters of the algorithm for different networks. The developed computer program is applied to three networks. Two of these networks are well known examples from the literature
the third network is a pressure zone of Ankara water distribution network. It is found out that, the parameters of the algorithm are related with the network, the case to be optimized and the developed computer program. The pressure penalty constant value varied depending on the pipe costs and the network characteristics. The mutation rate is found to vary in a range of [0.0075 &ndash
0.0675] for three networks. Elitism rate is determined as the minimum value for the corresponding population size. Crossover probability is found to vary in a range of [0.5 &ndash
0.9]. The methodology should be applied to determine the appropriate parameter set of genetic algorithm for each optimization study. Using the method described, fairly well results are obtained.
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Buroni, Giovanni. "Near Real-Time Detection Of Pipe Bursts in Water Distribution Systems." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016.
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The research work presented in the thesis describes a new methodology for the automated near real-time detection of pipe bursts in Water Distribution Systems (WDSs). The methodology analyses the pressure/flow data gathered by means of SCADA systems in order to extract useful informations that go beyond the simple and usual monitoring type activities and/or regulatory reporting , enabling the water company to proactively manage the WDSs sections.
The work has an interdisciplinary nature covering AI techniques and WDSs management processes such as data collection, manipulation and analysis for event detection. Indeed, the methodology makes use of (i) Artificial Neural Network (ANN) for the short-term forecasting of future pressure/flow signal values and (ii) Rule-based Model for bursts detection at sensor and district level.
The results of applying the new methodology to a District Metered Area in Emilia- Romagna’s region, Italy have also been reported in the thesis. The results gathered illustrate how the methodology is capable to detect the aforementioned failure events in fast and reliable manner.
The methodology guarantees the water companies to save water, energy, money and therefore enhance them to achieve higher levels of operational efficiency, a compliance with the current regulations and, last but not least, an improvement of customer service.
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Ruzza, Valentina. "Data assimilation techniques for leakage detection in water distribution systems." Doctoral thesis, Università degli studi di Padova, 2017. http://hdl.handle.net/11577/3422772.
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Leakage in pressurized water distribution systems is a major issue for water utilities today, because of the huge concerns over public health risks and the economic constraints on energy and resources. This thesis investigates innovative techniques for the detection of leakages in water distribution systems, relying on the calibration of network hydraulic models. The main goal is to suggest a method to reduce the costs of the field surveys currently required from the leakage detection activity on real systems.
An inverse model, based on the coupling between Kalman Filter based data assimilation techniques and network hydraulic models, is proposed and critically analyzed. The model is based on the knowledge of pressure heads, pipe flow rates and volume measurements, which can be easily obtained in any network with a limited effort and no technical troubles, with exception of the flow rate measurements.
The present work investigates different aspects of the proposed coupled model, related to the data assimilation technique used (Ensemble Kalman Filter or Ensemble Smoother), the type of hydraulic analysis developed (demand driven analysis through standard EpaNET or pressure driven analysis), the type of model parameters to be calibrated (the nodal leakage flow rates or the EpaNET emitter coefficients responsible for the nodal leakage flow rates), besides distinctions on the type of assimilated data and on the number and locations of available measurements.
Despite the fact that the success of the proposed technique depends on the specific features and topological structure of the network analyzed, this coupled model applied to synthetic water distribution systems proves to be effective for leakage detection and could be a competitive solution compared to the traditionally used district metering procedures in real world cases.La gestione delle perdite nelle condotte in pressione è una delle più importanti problematiche nei sistemi di distribuzione, per le preoccupazioni riguardo il rischio per la salute pubblica e per i vincoli economici su energia e risorse. Questa tesi intende analizzare tecniche innovative per l'individuazione delle perdite nei sistemi di distribuzione, basandosi sulla calibrazione dei modelli idraulici delle reti. Lo scopo principale è suggerire un metodo per ridurre i costi delle indagini di campo attualmente richieste dall'attività di ricerca perdite su reti reali. Un modello inverso, basato sull'accoppiamento tra tecniche di assimilazione dati basate sul filtro di Kalman e i modelli idraulici delle reti, è proposto ed analizzato criticamente. Il modello si basa sulla conoscenza di misure di pressione, portata e volume, le quali possono essere facilmente ottenute in ogni rete a costi contenuti e senza problemi tecnici, ad eccezione delle misure di portata. Il presente lavoro analizza differenti aspetti del modello accoppiato proposto, relativamente alla tecnica utilizzata per l'assimilazione dati (Ensemble Kalman Filter o Ensemble Smoother), al tipo di analisi idraulica sviluppata (demand driven attraverso la versione standard di EpaNET o pressure driven), il tipo di parametri da calibrare (le portate di perdita ai nodi oppure i coefficienti di emitter responsabili della perdita ai nodi), oltre che alla distinzione sul tipo di dati assimilati e sul numero e sulle posizioni di misura a disposizione. Nonstante il successo della tecnica proposta dipenda dalle caratteristiche peculiari e dalla struttura topologica della rete analizzata, questo modello accoppiato applicato a reti di distribuzione sintetiche si dimostra efficace per l'individuazione delle perdite e può costituire un'alternativa competitiva rispetto alle tecniche di distrettualizzazione correntemente applicate nei casi reali.
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Gelin, Martin, and Skogsberg Rikard Fridsén. "Water Contamination Detection With Artificial Neural Networks." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-295605.
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Drinking water is one of our most important re- sources, so the ability to reliably monitor harmful contaminations in our water distribution network is vital. In order to minimize false alarms for water monitoring, while keeping a high sensitivity, a machine learning approach was evaluated in this project. Measurement data captured with a new kind of sensor, an electronic tongue, was provided by Linköping university. The solution was an artificial neural network, in the structure of an Autoencoder, which could learn the dynamic behaviour of natural deviations and with a false alarm rate of approximately one false alarm per week. This was done by evaluating the data and assembling an input structure to account for daily cyclic phenomena, which then was used to train the neural network. The solution could detect anomalies as small as 1.5% by comparing the input with the reconstructed vector, and raise an alarm. In conclusion, an Autoencoder is a viable method for detecting anomalies in water quality.Drickvatten är en av våra mest värdefulla tillgångar, det är därför mycket viktigt att det finns sätt att pålitligt övervaka om dricksvattennätet blivit förorenat. För att kunna minimera antalet falsklarm och samtidigt ha hög känslighet mot dessa föroreningar undersöktes och implementerades en lösning med maskininlärningsalgoritmer. Mätdata tillhandahölls av Linköpings universitet och kom från en ny sensor kallad elektronisk tunga. Lösningen var ett artificiellt neuralt nätverk i form av en Autoencoder, som kunde lära sig det dynamiska beteende som ofarliga avvikelser utgjorde. Detta gav en lösning som i medel gav ett falsklarm per sju dagar. Detta gjordes genom att utvärdera rådata och konstruera en struktur på indata som tar hänsyn till dygnsbunda naturliga fenomen. Denna struktur användes sedan för att träna det neurala nätverket. Lösningen kunde upptäcka fel ner till 1.5% genom att jämföra indata med den rekonstruerade vektorn, och på så sätt ge ett alarm.
Kandidatexjobb i elektroteknik 2020, KTH, Stockholm
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Kausar, Rukhsana [Verfasser], and Stephan [Akademischer Betreuer] Trenn. "Analysis and modeling of water distribution network in the framework of switched DAEs / Rukhsana Kausar ; Betreuer: Stephan Trenn." Kaiserslautern : Technische Universität Kaiserslautern, 2019. http://d-nb.info/1193491517/34.
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Jansen, van Vuuren A., E. Pretorius, and N. Benade. "Catchment management-model evaluation : verifying data for the implementation of the water release module of the WAS program." Interim : Interdisciplinary Journal, Vol 4, Issue 1: Central University of Technology, Free State, Bloemfontein, 2005. http://hdl.handle.net/11462/426.
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Published ArticleThe Water Administration System (WAS) is designed to be a management tool for irrigation schemes and water offices that want to manage their water accounts and supply to clients through canal networks, pipelines and rivers. The ultimate aim of WAS is to optimize irrigation water management and minimize management-related distribution losses in irrigation canals. This research project focus on the implementation of the water release module of the WAS program at the Vaalharts irrigation scheme. WAS consists of four modules that are integrated into a single program that can be used on a single PC, a PC network system (in use currently at Vaalharts) or a multi-user environment. These modules can be implemented partially or as a whole, depending on the requirements of the specific scheme or office. The four modules are an administration module, a water request module; water accounts module and a water release module. The first three modules are already implemented at Vaalharts, while module four is implemented only partially. This module links with the water request module and calculates water releases for the main canal and all its branches allowing for lag times and any water losses and accruals. Any researcher in this field should first understand where water comes from and how it will be utilized before any calculations are attempted. Only then manipulation of the release volume can commence. To precisely calculate this water release, accurate data is needed to ensure that the correct volume of water is released into the canal network. This can be done by verifying existing data with field data. To optimize the management of the irrigation scheme the fully implemented WAS program need to be installed and running at the scheme. A series of data and calculation verification needs to be executed. The exercise will show the adequacy and correctness of the available database WAS uses to do the release calculation from. This will ensure improved management of the irrigation scheme, catchment and water resource sustainability. It is planned that the information generated from this project will be used in the compilation of an integrated catchment management information system, currently underway in the school of Civil Engineering and Built Environment at the Central University of Technology, Free State, South Africa.
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PULEO, Valeria. "Real-time optimal control of water distribution systems - Models and techniques, including intermittent supply conditions." Doctoral thesis, Università degli Studi di Palermo, 2014. http://hdl.handle.net/10447/91259.
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Newbold, James Richard. "Comparison and Simulation of a Water Distribution Network in EPANET and a New Generic Graph Trace Analysis Based Model." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/31177.
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The main purpose of this study was to compare the Distributed Engineering Workstation (DEW) and EPANET models. These two models are fundamentally different in the approaches taken to simulate hydraulic systems. To better understand the calculations behind each modelsâ hydraulic simulation, three solution methods were evaluated and compared. The three solution approaches were the Todini, Hardy-Cross, and DEW bisection methods. The Todini method was included in the study because of its similarities to EPANETâ s hydraulic solution method and the Hardy-Cross solution was included due to its similarities with the DEW approach. Each solution method was used to solve a simple looped network, and the hydraulic solutions were compared. It was determined that all three solution methods predicted flow values that were very similar.
A different, more complex looped network from the solution method comparison was simulated using both EPANET and DEW. Since EPANET is a well established water distribution system model, it was considered the standard for the comparison with DEW. The predicted values from the simulation in EPANET and DEW were compared. This comparison offered insight into the functionality of DEWâ s hydraulic simulation component. The comparison determined that the DEW model is sensitive to the tolerance value chosen for a simulation. The flow predictions between the DEW and EPANET models became much closer when the tolerance value in DEW was decreased.Master of Science
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Nemeth, Lyle John. "A Comparison of Risk Assessment Models for Pipe Replacement and Rehabilitation in a Water Distribution System." DigitalCommons@CalPoly, 2016. https://digitalcommons.calpoly.edu/theses/1599.
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A water distribution system is composed of thousands of pipes of varying materials, sizes, and ages. These pipes experience physical, environmental, and operational factors that cause deterioration and ultimately lead to their failure. Pipe deterioration results in increased break rates, decreased hydraulic capacity, and adverse effects on water quality. Pipe failures result in economic losses to the governing municipality due to loss of service, cost of pipe repair/replacement, damage incurred due to flooding, and disruptions to normal business operations. Inspecting the entire water distribution system for deterioration is difficult and economically unfeasible; therefore, it benefits municipalities to utilize a risk assessment model to identify the most critical components of the system and develop an effective rehabilitation or replacement schedule.
This study compared two risk assessment models, a statistically complex model and a simplified model. Based on the physical, environmental, and operational conditions of each pipe, these models estimate the probability of failure, quantify the consequences of a failure, and ultimately determine the risk of failure of a pipe. The models differ in their calculation of the probability of failure. The statistically complex model calculates the probability of failure based on pipe material, diameter, length, internal pressure, land use, and age. The simplified model only accounts for pipe material and age in its calculation of probability of failure. Consequences of a pipe failure include the cost to replace the pipe, service interruption, traffic impact, and customer criticality impact. The risk of failure of a pipe is determined as the combination of the probability of failure and the consequences of a failure. Based on the risk of failure of each pipe within the water distribution system, a ranking system is developed, which identifies the pipes with the most critical risk. Utilization of this ranking system allows municipalities to effectively allocate funds for rehabilitation.
This study analyzed the 628-pipe water distribution system in the City of Buellton, California. Four analyses were completed on the system, an original analysis and three sensitivity analyses. The sensitivity analyses displayed the worst-case scenarios for the water distribution system for each assumed variable. The results of the four analyses are provided below.
Risk Analysis
Simplified Model
Complex Model
Original Analysis
All pipes were low risk
All pipes were low risk
Sensitivity Analysis: Older Pipe Age
Identified 2 medium risk pipes
Identified 2 medium risk pipes
Sensitivity Analysis: Lower Anticipated Service Life
Identified 2 medium risk pipes
Identified 9 high risk pipes and 283 medium risk pipes
Sensitivity Analysis: Older Pipe Age and Lower Anticipated Service Life
Identified 1 high risk pipe and 330 medium risk pipes
Identified 111 critical risk pipes, 149 high risk pipes, and 137 medium risk pipes
Although the results appeared similar in the original analysis, it was clear that the statistically complex model incorporated additional deterioration factors into its analysis, which increased the probability of failure and ultimately the risk of failure of each pipe. With sufficient data, it is recommended that the complex model be utilized to more accurately account for the factors that cause pipe failures.
This study proved that a risk assessment model is effective in identifying critical components and developing a pipe maintenance schedule. Utilization of a risk assessment model will allow municipalities to effectively allocate funds and optimize their water distribution system.
Keywords: Water Distribution System/Network, Risk of Failure, Monte Carlo Simulation, Normal Random Variable, Conditional Assessment, Sensitivity Analysis.
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Yuzugullu, Onur. "Determination Of Chlorophyll-a Distribution In Lake Eymir Using Regression And Artificial Neural Network Models With Hybrid Inputs." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12612850/index.pdf.
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Chlorophyll-a is a parameter which can be used to understand the trophic state of water bodies. Therefore, monitoring of this parameter is required. Yet, distribution of chlorophyll-a in water bodies is not homogeneous and exhibits both spatial and temporal variations. Therefore, frequent sampling and high sample sizes are needed for the determination of chlorophyll-a quantities. This would in return increase the sampling costs and labor requirement, especially if the topography makes the location hard to reach. Remote sensing is a technology that can aid in handling of these difficulties and obtain a continuous distribution of chlorophyll-a concentrations in a water body. In this method, reflectance from water bodies in different wavelengths is used to quantify the chlorophyll-a concentrations. In previous studies in literature, empirical regression models that use the reflectance values in different bands in different combinations have been derived. Yet, prediction performances of these models decline especially in shallow lakes. In this study, the spatial distribution of chlorophyll-a in shallow Lake Eymir is determined using both regression models and artificial neural network models that use hybrid inputs. Unlike the models generated before, field measured parameters which can influence the reflectance values in remotely sensed images have been used in addition to the reflectance values. The parameters that are considered other than reflectance values are photosynthetically active radiation (PAR), secchi depth (SD), water column depth, turbidity, dissolved oxygen concentration (DO), pH, total suspended solids (TSS), total dissolved organic matter (TDOM), water and air temperatures, wind data and humidity. Reflectance values are obtained from QuickBird and World View 2 satellite images. Effect of using hybrid input in mapping the reflectance values to chlorophyll-a concentrations are studied. In the context of this study, three different high-resolution satellite images are analyzed for the spatial distribution of chlorophyll-a concentration in Lake Eymir. Field and laboratory studies are conducted for the measurement of parameters other than the reflectance values. Principle component analysis is applied on the collected data to decrease the number of model input parameters. Then, linear and non-linear regression and artificial neural network (ANN) models are derived to model the chlorophyll-a concentrations in Lake Eymir. Results indicate that ANN model shows better predictability compared to regression models. The predictability of ANN model increases with increasing variation in the dataset. Finally, it is seen that in determination of chlorophyll-a concentrations using remotely sensed data, models with hybrid inputs are superior compared to ones that use only remotely sensed reflectance values.
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Colombo, Fernando. "Calibração de modelos hidráulicos de redes de abastecimento de água de sistemas reais admitindo vazamentos." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-05042007-103413/.
Full textAbstract:
Considerando a necessidade do controle mais efetivo dos sistemas de distribuição de água para abastecimento, a calibração constitui etapa fundamental a ser trilhada para garantir a reprodução do comportamento dos sistemas sob as mais diversas condições operacionais. Apesar da importância da calibração e da diversidade de modelos construídos com esse propósito no ambiente acadêmico, essa prática não tem sido amplamente utilizada pelas companhias, que demonstram certa relutância em fazer uso de modelos matemáticos. É interessante, portanto, que os modelos existentes sejam intensivamente testados em sistemas reais para que se possam estabelecer diretrizes para a sua utilização, bem como uma maior confiança no seu emprego. O presente trabalho de pesquisa visou o estudo de aplicação de um modelo especialmente construído para a calibração de sistemas, através do qual é possível identificar variáveis de campo tais como rugosidades, diâmetros, parâmetros do modelo de vazamentos, etc. O modelo empregado é abrangente o suficiente para incorporar vazamentos e demandas variáveis com a pressão. Através dele, foram realizados dois estudos de caso e discutidas as razões pelas quais discrepâncias entre os valores simulados e observados foram detectadas, apesar da consistência das respostas produzidas via simulação. Algumas recomendações são feitas também no sentido de viabilizar estudos dessa natureza que possam produzir ferramental diretamente utilizável pelas concessionárias de água para abastecimento.Considering the need for more effective control of water supply distribution systems, the calibration constitutes fundamental step to guarantee that the system behavior under several operational conditions can be reproduced. Instead of the importance of calibration and the variety of models built by the academy for this purpose, this practice has not been broadly used by the water industry, which demonstrates certain reluctance regards the use of mathematical models. It is interesting, hence, that existing models are intensively tested in real systems to establish guidelines and consequent confidence in their use. The present research focused on the study of a model especially built for the calibration of water supply systems, through which it is possible identify field variables such as roughness, diameters, parameters of leakage model, etc. The model is comprehensive enough to incorporate leakage and pressure driven demands. Two study cases were analyzed supported by the model and discussed the reasons by which disagreement between simulated and observed data were verified, instead of the consistency of results produced by simulation. Some recommendations are made to become practical this kind of study as useful tool for the water industry.
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Shukla, Raghupati. "A feasibility analysis of the use of the Skipworth model for Bridgetown Water Supply Network and a Whole Life Costing to compare the water distribution systems at Greenvale pumping station." Thesis, Curtin University, 2012. http://hdl.handle.net/20.500.11937/282.
Full textAbstract:
To promote efficient use of water resources in the developing world, there is a recognized need to make the best use of infrastructure developments and application of Whole Life Costing (WLC) in combination with computational optimization. In this way the efficiency of Water Management in public and private areas can be improved. This case study, a feasibility study and whole life costing analysis, was designed to assess the feasibility of the Skipworth model on the Bridgetown Water Supply Network.The Skipworth model was proved to be more cost effective than the current models used by the Water Corporation at Bridgetown. The whole life costing was conducted with Greenvale Pumping Station in order to compare the water distribution methods, Pump, Gravity and Combined Systems. The feasibility studies provided much information to the Water Corporation and Water Organizations of Australia to enable changes in the existing Water Distribution System of Australia. The whole life costing provided data which proved the Gravity and Combined systems were more cost effective than the current Pumping system. Recommendations were made for the implementation of the Skipworth model at Bridgetown and a Gravity and Combined system at Greenvale.