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Dissertations / Theses on the topic 'Water distribution systems'
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1
Maier, Stefan Heinrich. "Modelling water quality for water distribution systems." Thesis, Brunel University, 1999. http://bura.brunel.ac.uk/handle/2438/5431.
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Maintaining water quality in distribution systems has become a prominent issue in the study of water networks. This thesis concentrates on disinfectant and particle counts as two important indicators of water quality. The models discussed in this work are based on data collected by the author. The experimental set-up and procedure are described and observations of particle counts, particle counter size distributions, monochloramine as disinfectant, temperature, heterotrophic plate counts and epifluorescence microscopy counts are reported. A model of the response of particle counts to an increase in flow is developed. This model is obtained from specification derived from the data and assumptions, and is validated by its interpretability and its fit to data. A local shear-off density and an initial biofilm shedding profile were introduced and thus a linear model for this part of the water quality dynamics could be obtained. A procedure for the identification of the parameters of the local shear-off function and for the determination of the biofilm shedding profile is presented. This profile can be used to provide information about the status of the distribution system in terms of shear-off from the biofilm on the pipe walls. Monochloramine decay dynamics are investigated. The chlorine meter data is preprocessed with the help of titration data to correct meter drift. The data is then used in calibrating two different possible chlorine models: a model with a single decay coefficient and a model with bulk decay coefficient and wall demand (as used in Epanet). Important difficulties in identifying these parameters that come about because of the structure of the models are highlighted. Identified decay coefficients are compared and tested for flow, inlet chlorine and temperature dependence. The merits and limits of the approach to modelling taken in this work and a possible generalisation are discussed. The water industry perspective and an outlook are provided.
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Tsegaye, Seneshaw Amare. "Flexible Urban Water Distribution Systems." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4597.
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With increasing global change pressures such as urbanization and climate change, cities of the future will experience difficulties in efficiently managing scarcer and less reliable water resources. However, projections of future global change pressures are plagued with uncertainties. This increases the difficulty in developing urban water systems that are adaptable to future uncertainty.
A major component of an urban water system is the distribution system, which constitutes approximately 80-85% of the total cost of the water supply system (Swamee and Sharma, 2008). Traditionally, water distribution systems (WDS) are designed using deterministic assumptions of main model input variables such as water availability and water demand. However, these deterministic assumptions are no longer valid due to the inherent uncertainties associated with them. Hence, a new design approach is required, one that recognizes these inherent uncertainties and develops more adaptable and flexible systems capable of using their active capacity to act or respond to future alterations in a timely, performance-efficient, and cost-effective manner.
This study develops a framework for the design of flexible WDS that are adaptable to new, different, or changing requirements. The framework consists of two main parts.
The first part consists of several components that are important in the pre and post--processing of the least-cost design methodology of a flexible WDS. These components include: the description of uncertainties affecting WDS design, identification of potential flexibility options for WDS, generation of flexibility through optimization, and a method for assessing of flexibility. For assessment a suite of performance metrics is developed that reflect the degree of flexibility of a distribution system. These metrics focus on the capability of the WDS to respond and react to future changes. The uncertainties description focuses on the spatial and temporal variation of future demand.
The second part consists of two optimization models for the design of centralized and decentralized WDS respectively. The first model generates flexible, staged development plans for the incremental growth of a centralized WDS. The second model supports the development of clustered/decentralized WDS. It is argued that these clustered systems promote flexibility as they provide internal degrees of freedom, allowing many different combinations of distribution systems to be considered. For both models a unique genetic algorithm based flexibility optimization (GAFO) model was developed that maximizes the flexibility of a WDS at the least cost.
The efficacy of the developed framework and tools are demonstrated through two case study applications on real networks in Uganda. The first application looks at the design of a centralized WDS in Mbale, a small town in Eastern Uganda. Results from this application indicate that the flexibility framework is able to generate a more flexible design of the centralized system that is 4% - 50% less expensive than a conventionally designed system when compared against several future scenarios. In addition, this application highlights that the flexible design has a lower regret under different scenarios when compared to the conventionally designed system (a difference of 11.2m3/US$). The second application analyzes the design of a decentralized network in the town of Aura, a small town in Northern Uganda. A comparison of a decentralized system to a centralized system is performed, and the results indicate that the decentralized system is 24% - 34% less expensive and that these cost savings are associated with the ability of the decentralized system to be staged in a way that traces the urban growth trajectory more closely. The decentralized clustered WDS also has a lower regret (a difference of 17.7m3/US$) associated with the potential future conditions in comparison with the conventionally centralized system and hence is more flexible.
3
Mashkour, Mohammad. "Micro hydropower in water distribution systems." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/17855/.
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Considering various applications of Pump as Turbine (PAT) as an effective source of reducing the
equipment cost in small hydropower plants as well as the selecting process of appropriate location
and suitable machinery are the main concerns of this study. Vary range of PAT settings criteria
has been propound by taking into account the State-of-the-Art researches.
The purpose of this study is to establish the effectiveness of pump as turbine, considering all the
possible obstacles such as producer’s market interests, accessibility of technical information and
mechanical limitation. Cutting-edge scientific researches concerning PAT have been proposed by
implementation of various approaches. The most challenging criteria of PAT, which is selecting
the appropriate machinery, has been investigated subsequently.
A comparative methodology to model the effectiveness of PATs, both numerical and experimental,
has been developed based on the efficiency. The mechanical reliability of the hydropower devices
in situ, prototype and numerical investigation have been reviewed. These results have been
obtained through measurements and optimization of the simulated system by means of
characteristic methods against the established PAT system in many different case studies.
Water Distribution Networks (WDNs) allow to obtain a widespread and globally significant
amount of produced energy by exploiting the head drop due to the network pressure control
strategy for leak reductions. Replacing PAT in water distribution networks regarding to all the
possible obstacles, will reduce the final cost and will improve the expected efficiencies, as much
as the reduction of environmental impacts.
This study definitively answers the question whether PAT is an effective alternative in WDNs.
The comparative approach also aims for a better understanding of the impact of PAT on the
transition to renewable energy systems.
4
Qin, Xiaoli, and 秦小麗. "Biofilms in drinking water distribution systems." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B4150866X.
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Borovik, Irina. "Bursts identification in water distribution systems." Thesis, De Montfort University, 2009. http://hdl.handle.net/2086/2392.
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The presented thesis investigates the identification of burst locations in water distribution systems (WDS) by analysis of field and simulation experimental data. This required the development of a new hybrid method of burst detection and sizing, and also a burst location identification algorithm. Generally, existing practice relies on a combination of some simple procedure and experience of the involved staff and cannot be easily automated. The practical methods are based on direct manifestation of burst on the surface or on systematically surveying suspected areas e.g. by using listening sticks, such methods are very time consuming. The proposed burst location algorithm is based on comparing data by means of statistical analysis of field data with results of water network simulation. An extended network hydraulic simulator is used to model pressure dependent leakage terms. The presence of a burst changes the flow pattern and also pressure at network nodes which may be used to estimate the burst size and its location. The influence of such random factors as demand flows and background leakage on the process of burst detection is also considered. The field data is from a generalised fixed area and variable area (FAVOR) test where inlet pressure is being stepped up and down and the following variables are measured: inlet flow, inlet pressure (head) and pressure at a number of selected sensitive nodes. The method has three stages and uses two different models, one is inlet flow model (IFM) to represent the total inlet flow and another is the extended hydraulic model to simulate different burst locations. Initially the presence of a potential burst is investigated. If this is confirmed precise values of the demand, background leakage flow and burst flow in IFM are subsequently estimated. They are used to identify the burst site at the third stage of the method. The method can be easily adapted for practical use. It requires data from experiments carried out at night between 1am and 5am and involves placing typically about 20 temporary loggers to collect the measurements during this period. It also requires the availability of a hydraulic model which normally is in the possession of a water company. The program has been implemented in the Matlab package and is easy to use. The current methodology is tuned to identify a single burst but can be generalised to identify locations of multiple bursts.
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Sempewo, Jotham Ivan. "Transitioning of urban water distribution systems." Thesis, University of Birmingham, 2013. http://etheses.bham.ac.uk//id/eprint/4227/.
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The upgrade of urban water distribution systems (UWDS) amidst uncertain global change pressures is a challenging problem. To deal with this dilemma water utilities require approaches that enable UWDS to be transitioned at a minimal technical and socio-economic impact as uncertainties become known. A review of approaches for upgrading UWDS shows that existing cost models are skewed towards operation and maintenance costs without consideration for future transitionability. This thesis describes approaches for the sustainable transition of UWDS and their application on case studies. The thesis develops a conceptual framework for the analysis of UWDS transitions. It then develops a Socio-economic Impact Indicator (SII) framework based on Multi Criteria Decision Analysis and the Analytical Hierarchical Process to estimate impacts in an urban area due to UWDS transitions. It also develops an approach for modelling socio-technical transitions based on multinomial logistic regression. The thesis then develops an UWDS transition design approach that considers not only operation and maintenance costs (leakage and burst costs) but also transitionability and future socio-technical impacts costs. The developed approaches have been tested on case studies as proof of concept. Maximum cost saving can be realised when existing UWDS are upgraded with consideration of future UWDS transitionability.
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Mansoor, M. A. M. "Performance assessment of water distribution systems." Thesis, Loughborough University, 2007. https://dspace.lboro.ac.uk/2134/12569.
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Water distribution systems are often susceptible to failure events, mainly due to component malfunctions, increase in demand and pollution events. However, levels of service to the consumers cannot be compromised. Therefore, to understand the behaviour of distribution systems, performance assessment is important. In this thesis, problem of failure events in water distributions system is discussed and the causes of failure are described. Component failures are selected to simulate the extreme situations in the distribution systems. Random nature of the component failures are simulated by way of employing a Monte Carlo technique based on the failure probabilities of the components. The methodology was illustrated with an example application. Appropriateness of existing network analysis methods to simulate failure events is analysed and their shortcomings identified. To demonstrate the impact of component failures, they are simulated with the hydraulic network analysis model. The traditional demand driven network analysis approach is not sensitive to pressure variations in the system. Therefore, simulating failures with demand driven analysis methods produces inaccurate flows at the nodes. The pressure dependent demand analysis on the other hand, is capable of accommodating the flow redistributions in the water distribution network, caused by failure events. The pressure dependent functions used in the analysis are meant to predict the flows that are consumed by the secondary networks (tree network supplied from primary node). However, representing the secondary network behaviour by using only a few coefficients (as in the PDD functions) do not always results in correct predictions. An alternative method that is based on micro level models (secondary networks) is proposed. Micro level models try to simulate the exact network conditions, taking into account of the consumers piping arrangements. Applying micro level models to a large real network will be a tedious process, as the size of the network will increase by many folds. To avoid the difficulties in the micro level modeling, a method based on artificial neural networks (ANN) is introduced. The ANNs mimic the behaviour of secondary networks in the micro level model. Therefore, instead of physically attaching the secondary networks, ANNs are incorporated with the analysis. The ANN based network analysis model predicts the pressure dependent demand outflows at the nodes. The behaviour of water distribution system is evaluated using performance measures. Existing performance indicators are reviewed and their shortcomings identified. New measures are proposed that give better insights into the behaviour of the system and also the failure experience of the consumers. The improved performance assessment method is applied to a case study network and results were explained.
8
Greene, James J. "Global optimization of water distribution systems." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-10062009-020212/.
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Qin, Xiaoli. "Biofilms in drinking water distribution systems." Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B4150866X.
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Jung, Donghwi. "Robust and Resilient Water Distribution Systems." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/311454.
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The purpose of a water distribution system (WDS) is to deliver the required amount of water to the customer under the desired pressure and quality. However, demand change and component failure result in low pressures at customer taps and make it difficult to achieve the goal. To mitigate the impact of the disturbances, system performance measure such as robustness and resilience can be considered in the WDS design and operation. Robustness is generally defined as an ability of the systems to maintain its function under a defined set of disturbance. On the other hand, Resilience is a system's ability to prepare and recover from a failure. The goal of this dissertation is to develop methodologies to enhance WDS robustness and resilience. In robustness-based design, reliability has been considered. Reliability is generally defined as the system's ability to provide an adequate service to customers under uncertain system condition and measured by the probability that stochastic nodal pressures are greater than or equal to a prescribed minimum pressure. However, although improving reliability will improve system robustness, the question is how the reliability index will improve system robustness. Robustness incorporates the variation of system performance; an additional aspect of system performance that reliability does not encompass. Pipe bursts are the most common failure in WDS. Therefore, promptly detecting and locating bursts will decrease the failure duration and increase system resilience. While many burst detection methods are available, identifying the method with the highest detectability is important to system owners/operators. However, to date, no cross comparisons of these methods have been completed for burst detection using a common data set. In addition, most traditional burst detection methods do not have a mechanism to include system operational changes. This dissertation is composed of three journal manuscripts that address these three key issues on WDS robustness and resilience. For WDS robustness improvement, a new robustness index is developed and used for multi-objective robustness-based design. The robustness-based design is compared to conventional reliability-based design. For WDS resilience improvement, the best method among six Statistical Process Control (SPC) methods is identified in terms of detection effectiveness and efficiency. Finally, a burst detection method applicable under system operational condition change is posed.
11
Silvestry, Rodriguez Nadia. "Silver Disinfection in Water Distribution Systems." Diss., The University of Arizona, 2008. http://hdl.handle.net/10150/194756.
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Silver was evaluated as disinfectant to maintain water quality in water distribution system. It was used to inhibit growth of two opportunistic bacteria in planktonik form and in biofilm formation in Robbins devices with stainless steel and PVC surfaces. The results of this work show that silver is a potential secondary disinfectant to be used in water distribution systems
12
Hainsworth, G. D. "Measurement uncertainty in water distribution telemetry systems." Thesis, Nottingham Trent University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383304.
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Jonkergouw, Philip M. R. "Simulating chlorine decay in water distribution systems." Thesis, University of Exeter, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.441805.
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Kartakis, Sokratis. "Next generation cyber-physical water distribution systems." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/52704.
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Over the last decade, there has been a trend where water utility companies aim to make water distribution networks more intelligent in order to improve their quality of service, reduce water and energy waste, minimize maintenance costs etc., by incorporating Information and Communications Technologies (ICT). Current state of the art solutions use expensive power hungry deployments to monitor and transmit water network states periodically in order to detect anomalous behaviors, such as water leakage and bursts, and control water network assets. However, more than 97% of water network assets are found in remote areas, away from power and are often in geographically remote underpopulated areas; facts that make current approaches unsuitable for next generation more dynamic adaptive water networks. Battery-driven wireless sensor/actuator-based solutions are theoretically the perfect choice to support next generation cyber-physical water distribution systems. In this context, this thesis answers the question: "How can the communication be optimized to achieve sustainable Cyber-Physical Systems (CPS) deployed in such harsh environments exploiting limited resources by combining Information, Control, and Communication theory (I2C)? " In order to efficiently utilize underground wireless sensor and actuator network infrastructures, the concepts of edge data processing, anomaly detection and localization, based on compression, stream analyses and graph theory, are introduced. Furthermore, energy optimization and network sustainability by exploiting data-rate and communication scheduling adaptation, based on Lyapunov optimization, is proposed; while the benefits of aperiodic communication are investigated by accommodating event-triggered control technique into smart water networks. In addition to simulations based on real data, WaterBox and BentoBox evaluation platforms were developed to evaluate the proposed algorithms and prove the benefits of event-triggered control and Low Power Wide Area (LPWA) communication technologies against the state-of-the-art solutions. Through theoretical analysis, simulations, and real testbed experiments, the proposed algorithms and systems are shown to outperform contemporary solutions by achieving communication and actuation optimization, data reliability enhancement, while ensuring the sustainable operation of smart water networks. The work presented in this thesis should be of interest to researchers in the emerging areas Cyber-Physical Systems (CPS), Internet of Things (IoT), and Information and Communications Technology (ICT) for smart sustainable cites.
15
Huang, Danguang. "Flexible design of urban water distribution systems." Thesis, University of Birmingham, 2011. http://etheses.bham.ac.uk//id/eprint/2948/.
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Urban water distribution systems (UWDS) are highly inter-connected and under many uncertainties from water demand, pipe roughness, and component failure. Accurate projections of these uncertainties are almost impossible, and thus it may not be a proper method to design the system to meet its performance criteria for the forecasted scenario. The system is designed for the deterministic not for the uncertainties, as a result it may not be efficient or effective to be operated under different future scenarios. Flexible design is shown as a useful strategy to cost-effectively respond to uncertainties because of its consideration of uncertainties in advance, and has been successfully applied in many engineering systems. The objective of flexible design is to identify flexibility sources in UWDS and embed them into the system design to respond to uncertainties. The thesis discussed different terms to define the property of the system to respond to uncertainties and proposed a definition of flexibility for UWDS. It then proposed different measures to indicate flexibility value and introduced an efficient method to handle numerous uncertain parameters in the model. It also develops an efficient method to identify high value flexibility sources based on the Flexibility Index. Finally the thesis presents a flexibility-based optimisation model that enable water engineers to compare different flexible design alternatives and generate optimal solutions. A definition of flexibility in UWDS is proposed to illustrate broadly its property to respond to uncertainties, since it is not so useful, or at least in this thesis to distinguish similar terms to define the property of the system to respond to uncertainties. Identified flexibility sources by the proposed method is not useful for the flexibility-based optimization model to design a system, but it might be a powerful tool to locate the weak points in the system or provide better update options during rehabilitation of the system. The computational efficiency of the proposed flexibility-based optimisation model was demonstrated by dramatic decreasing on the number of the required hydraulic simulation in the case study. Flexible designs in the case study are more expensive than inflexible design, but have better hydraulic performance under uncertainties.
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Rust, Tertius. "Predicting water quality in bulk distribution systems." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/95838.
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Thesis (MScEng)--Stellenbosch University, 2014.ENGLISH ABSTRACT: The increased water demand to be supplied by municipal water distribution systems, and subsequent increased storage period of reserve water, may have implications with regards to water ageing and subsequently may have an impact on health and safety. Current master planning design standards could have a negative effect on water residence time. The decay of the disinfectant potential is a function of the residence time in the distribution system. The objective of this study is to identify and measure existing systems to optimally increase water quality in a distribution system while supplying an increase in demand, dealing with the deterioration of pipe infrastructure and the introduction of alternative water sources. To do this, one must understand the dynamics of water networks and the parameters that affect water quality. The foundation of a water quality model is based on the construction of an accurate hydraulic model. To identify and measure these systems, one must understand the aspects of water purification and the techniques used to achieve water standards in a distribution system. These techniques and standards play a huge role in the prediction of water quality. In this paper the fundamentals and techniques used to determine and measure such a model are discussed. Consequently, additional design parameters to assess water quality must be incorporated into current master planning practice to optimally design water networks. These models are used to determine the appropriate levels of disinfectant at strategic locations in a system. To illustrate these design parameters and systems currently used in practice, a case study involving Umgeni Water (UW) and EThekwini municipality (EWS) was used to determine the most suitable disinfectant strategy for a municipality’s distribution system. Future scenarios and the impact of disinfectant mixing and increased residence time of the water in the system were also determined. The use of this water quality model in a distribution system will ultimately provide a sustainable platform for a risk monitoring procedure.
AFRIKAANSE OPSOMMING: Die verhoogde aanvraag na water in munisipale voorsieningstelsels, en die daaropvolgende verhoogde stoortydperk van reserwe water, kan implikasies inhou met betrekking tot water veroudering waarna dit ‘n impak op gesondheid en veiligheid kan hê. Huidige meesterbeplanning ontwerpstandaarde kan 'n noemenswaardige uitwerking op water retensietyd hê, veral omdat chloor se vervaltyd op sy beurt 'n funksie van water retensietyd is. Die doel van hierdie studie is om 'n prosedure te identifiseer om watergehalte optimaal te verhoog in 'n waterverspreidingstelsel, terwyl die toename in water aanvraag voortduur. Om dit te kan doen moet die dinamika van water netwerke en die parameters wat die gehalte van water beïnvloed, bestudeer word. Die opstel van 'n waterkwaliteit model is gebaseer op die bou van 'n akkurate hidrouliese model. Om uiteindelik die ontwerp van 'n waterkwaliteit oplossing suksevol uit te voer, moet 'n mens al die aspekte van watersuiwering en die tegnieke wat gebruik word om waterstandaarde te handhaaf in 'n verspreidingstelsel verstaan. In hierdie verslag word die beginsels en tegnieke wat gebruik word om so 'n model op te stel, bespreek. Bykomende waterkwaliteit ontwerpparameters moet by huidige meesterbeplanning gevoeg word om waternetwerke optimaal te ontwerp. Hierdie modelle word gebruik om die geskikte vlakke van ontsmettingsmiddel op strategiese plekke in 'n stelsel te bepaal. 'n Gevallestudie van Umgeni Water (UW) en eThekwini-munisipaliteit (EWS) is gebruik om die mees geskikte ontsmettingsmiddel strategie vir 'n munisipaliteit se verspreiding te illustreer. Toekomstige scenario's en die impak van ontsmettingsmiddelvermenging en verhoogde retensietyd van die water in die stelsel sal ook bepaal kan word. Die gebruik van hierdie gehalte-watermodel in 'n verspreidingstelsel sal uiteindelik 'n volhoubare platform vir 'n risiko moniteringstelsel inhou.
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Boe-Hansen, Rasmus. "Microbial growth in drinking water distribution systems /." Environment & Resources, DTU, 2001. http://www2.er.dtu.dk/publications/fulltext/2001/MR2001-075.pdf.
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Nobliá, Matilda, and Christian Ryan. "Contamination Event Detection in Water Distribution Systems." Thesis, KTH, Skolan för elektro- och systemteknik (EES), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-214698.
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In any society, making sure that its citizens havea clean water supply is a fundamental issue. By modernizingthe way water distribution systems (WDSs) are monitored andcontrolled, the impact of contamination can be maintained andminimized. By using sensors that monitor relevant physicalparameters, a system that detects contamination and limitspopulation exposure can be designed. To achieve this, the workpresented in this report is focused on three main topics.Firstly, parameters for determining water quality are examined.This is the basis for choosing relevant sensors. Secondly,a study of contamination event detection (CED) is presented, inparticular a method to determine whether water is contaminatedor not based on sensor measurements is proposed. This iscompleted through the use of binary hypothesis testing as wellas examining existing sensors. Thirdly, the problem of optimalsensor placement in a WDS is studied. In extension, a greedyalgorithm is implemented to optimally place sensors in a modelof real-world network.
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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.
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Schal, Stacey L. "WATER QUALITY SENSOR PLACEMENT GUIDANCE FOR SMALL WATER DISTRIBUTION SYSTEMS." UKnowledge, 2013. http://uknowledge.uky.edu/ce_etds/13.
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Water distribution systems are vulnerable to intentional, along with accidental, contamination of the water supply. Contamination warning systems (CWS) are strategies to lessen the effects of contamination by delivering early indication of an event. Online quality monitoring, a network of sensors that can assess water quality and alert an operator of contamination, is a critical component of CWS, but utilities are faced with the decision of what locations are optimal for deployment of sensors. A sensor placement algorithm was developed and implemented in a commercial network distribution model (i.e. KYPIPE) to aid small utilities in sensor placement. The developed sensor placement tool was then validated using 12 small distribution system models and multiple contamination scenarios for the placement of one and two sensors.
This thesis also addresses the issue that many sensor placement algorithms require calibrated hydraulic/water quality models, but small utilities do not always possess the financial resources or expertise to build calibrated models. Because of such limitations, a simple procedure is proposed to recommend optimal placement of a sensor without the need for a model or complicated algorithm. The procedure uses simple information about the geometry of the system and does not require explicit information about flow dynamics.
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Webb, David W. "WATER QUALITY VARIATIONS DURING NITRIFICATION IN DRINKING WATER DISTRIBUTION SYSTEMS." Master's thesis, University of Central Florida, 2004. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4492.
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This thesis documents the relationship among the major water quality parametersduring a nitrification episode. Nitrification unexpectedly occurred in a chloraminated pilotdrinking water distribution system practicing with a 4.0 mg/L as Cl[subscript 2] residual dosed at 4.5:1Cl[subscript 2]:NH[subscript 3]-N. Surface, ground and sea water were treated and disinfected withmonochloramines to produce finished water quality similar to regional utility water quality.PVC, galvanized, unlined cast iron and lined iron pipes were harvested from regionaldistribution systems and used to build eighteen pilot distribution systems (PDSs). The PDSswere operated at a 5-day hydraulic residence time (HRT) and ambient temperatures.As seasonal temperatures increased the rate of monochloramine dissipation increaseduntil effluent PDS residuals were zero. PDSs effluent water quality parameters chloraminesresidual, dissolved oxygen, heterotrophic plate counts (HPCs), pH, alkalinity, and nitrogenspecies were monitored and found to vary as expected by stoichiometry associated withtheoretical biological reactions excepting alkalinity. Nitrification was confirmed in thePDSs. The occurrence in the PDSs was not isolated to any particular source water.Ammonia for nitrification came from degraded chloramines, which was common among allfinished waters. Consistent with nitrification trends of dissolved oxygen consumption,ammonia consumption, nitrite and nitrate production were clearly observed in the PDSs bulkwater quality profiles. Trends of pH and alkalinity were less apparent. To controlnitrification: residual was increased to 4.5 mg/L as Cl[subscript 2] at 5:1 Cl[subscript 2]:NH[subscript 3]-N dosing ratio, and theHRT was reduced from 5 to 2 days. Elimination of the nitrification episode was achieved after a 1 week free chlorine burn.M.S.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Civil and Environmental Engineering
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Alere, Ilze. "Aspects of water quality dynamics in drinking water distribution systems." Licentiate thesis, Luleå tekniska universitet, 1997. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-16878.
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Shi, Yi. "Biofilm impacts on water quality in drinking water distribution systems." Thesis, Cardiff University, 2018. http://orca.cf.ac.uk/111782/.
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Drinking water distribution systems (DWDSs) account for the majority of the infrastructure for transporting water from treatment plants to customers’ tap. During the transportation, water quality deteriorates due to the unavoidable accumulation of biofilm within the pipelines. The microbial activity and ecology within the biofilm have great impact on the water quality degradation process. Within DWDSs using chloramine as disinfectant, nitrification caused by nitrifying bacteria is increasingly becoming a concern as it poses a great challenge for maintaining water quality. In order to control nitrification in DWDSs, it is essential to consider both the nitrifying bacteria and their shelter. Hence, the overall aim of this study is to investigate nitrification properties under different operational conditions, in addition to biofilm characteristics in chloraminated water distribution systems. To achieve the aim, nitrifying biofilm was firstly incubated within a flow cell experimental facility. A total of four test phases were conducted to investigate the effects on the extent of nitrification of five flow rates (2, 4, 6, 8 and10 L/min) and four disinfection strategies (total chlorine=1mg/L, Cl2/NH3=3:1; total chlorine=1mg/L, Cl2/NH3=5:1; total chlorine=5mg/L, Cl2/NH3=3:1; and total chlorine=5mg/L, Cl2/NH3=5:1). Physico-chemical parameters and nitrification indicators were monitored during the tests. The main results from the study indicate that nitrification is affected by hydraulic conditions and the process tends to be severe when the fluid flow transforms from laminar to turbulent (2300 < Reynold number < 4000). Increasing disinfectant concentration and optimizing Cl2/NH3 mass ratio were found to have limited efficacy for controlling nitrification. Furthermore, several nitrification indicators were evaluated for their prediction efficiency and the results suggest that the change of nitrite, together with total organic carbon (TOC) and turbidity can indicate nitrification potential more efficiently. At the end of the tests, genomic DNA from biofilm and bulk water from each flow cell unit running at different operational conditions were subjected to a next generation sequencing (NGS) analysis by Illumina MiSeq. The results obtained showed that the microbial community and structure was different between biofilm and water samples. There was no statistical difference in microbial community in biofilm identified between different hydraulic regimes, suggesting that biofilm is a stable matrix to environment. Results further showed that Cl2/NH3 mass ratio had obvious effect on microbial structure in biofilm. This suggests that excessive ammonia is an influencing factor for microbial activity within biofilm. Within bulk water, species richness and diversity tended to be higher at lower hydraulic regimes. This confirms the influence of hydraulic condition on biofilm mechanical structure and further material mobilization to water. Opportunic pathogens such as Legionella and Mycobacterium were detected in abundance in the experimental system. This confirms that nitrification can lead to a decrease of water quality and microbial outbreaks. The characteristics of extracellular polymeric substance (EPS) from biofilm conditioned under different operational conditions were also analysed. Carbohydrate was found to be the main components within biofilm’s EPS. EPS composition and structure were found to be governed by operational conditions, but no simple linear relationship was found. This suggests the interactive effects of EPS properties, hydraulics and disinfectant strategies. EPS effects on disinfection were evaluated via disinfectant decay tests. EPS was confirmed to have an influencing in biofilm overcoming disinfection.
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Oliveira, Paulo Jose A. "Spatial and Temporal Modeling of Water Demands for Water Distribution Systems." University of Cincinnati / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1613748818835557.
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Bene, J. G. (József Gergely). "Pump schedule optimisation techniques for water distribution systems." Doctoral thesis, Oulun yliopisto, 2013. http://urn.fi/urn:isbn:9789526202662.
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Abstract This thesis deals with the pump schedule optimisation of regional water distribution systems. The aims and the possible applications of the presented methods differ from each other; all of them are intended to solve a particular but realistic problem. The developed techniques use the capacity of the water reservoirs in order to find the optimal pump-schedule of the system. The optimisation task is always deterministic and discrete in time; the stochastic behaviour of the water consumptions is approximated by expected values. A so-called neutral genetic algorithm equipped with new constraint handling is presented first. The method is able to solve the scheduling problems of real-size and complex networks, e.g. the network of Budapest with coupled hydraulic simulations where both variable and fixed speed pumps are in the network. The results are compared to other ones obtained by widely used genetic algorithms and state-of-the-art general purpose optimisation solvers. A dynamic programming based method was also carried out which provides the global optimum of the so-called ’combinatorial’ pump scheduling problems. This modelling type is very common in the industry, which can be used if the operation points of the pumps take discrete values. The basic idea of the method is exploiting the ’permutational invariance’ of the model which results in a perfect discretisation of the state space without any loss of information. An approximate dynamic programming technique is also presented which solves the same type of problems as the formerly mentioned genetic algorithm does. The technique splits the water network model into smaller units, namely into the so-called well fields and the main distribution system. The state space of the main distribution system was further decreased while the quality of the results does not decay. A part of the test examples is the same as in the case of the former presented genetic algorithm; thus, the two methods can be compared. Finally, a small water network fed by a single variable speed pump was investigated. The presented methods are based on the minimisation of the specific energy consumption. The gained results are compared to ones obtained using a high-resolution discrete dynamic program. Novel optimisation techniques for water distribution network pump scheduling were developed in this work. A particular focus was put on the dynamics between pumping, water reservoirs, and water use. The work shows the applicability of the approach via numerous realistic simulation case studiesTiivistelmä Työ käsittelee alueellisten vedenjakelujärjestelmien pumppauksen aikataulutuksen optimointia. Esitettyjen menetelmien tavoitteet ja mahdolliset sovellukset poikkeavat toisistaan. Kaikki on kuitenkin tarkoitettu tiettyjen todellisten ongelmien ratkaisemiseen. Kehitetyt tekniikat käyttävät vesivarastojen kapasiteettia optimaalisen pumppausohjelman löytämiseksi. Jokainen optimointitehtävä on aikadiskreetti ja deterministinen, vedenkulutuksen stokastista käyttäytymistä on approksimoitu odotusarvoilla. Ensimmäiseksi työssä esitetään ns. neutraaleja geneettisiä algoritmeja varustettuna rajoitusten käsittelyllä. Menetelmällä voidaan ratkaista skedulointiohjelmia reaalimittakaavaisille ja monimutkaisille verkostoille (esim. Budapestin verkosto varustettuna hydraulisilla simuloinneilla, sekä muuttuvanopeuksisilla että vakionopeuksisilla verkoston pumpuilla). Tuloksia verrataan toisiin yleisesti käytössä olevilla geneettisillä algoritmeilla saatuihin, sekä johtavilla yleiskäyttöisillä optimointitekniikoilla saatuihin tuloksiin. Työssä käytettiin myös dynaamiseen ohjelmointiin pohjaavaa menetelmää, jolla saadaan globaali optimi ns. "kombinatoorisille" pumppauksen aikataulutusongelmille. Tällainen mallinnustapa on hyvin yleistä teollisuudessa. Sitä voidaan käyttää, jos pumppujen toimintapisteet saavat diskreettejä arvoja. Menetelmän perusajatuksena on "permutationaalisen invarianssin" hyväksikäyttäminen, josta seuraa tila-avaruuden virheetön diskretointi ilman informaation häviämistä. Työssä esitellään myös approksimoidun dynaamisen ohjelmoinnin tekniikka, jonka avulla voidaan ratkaista samantyyppisiä ongelmia kuin yllämainituilla geneettisillä algoritmeilla. Tämä tekniikka jakaa vesijohtoverkoston mallin pienempiin yksiköihin: lähdekenttiin ja pääjakeluverkostoon. Pääjakeluverkoston tila-avaruutta voitiin edelleen pienentää ilman, että tulosten laatu heikkeni. Osa käsitellyistä esimerkkitapauksista on samoja kuin edellämainittujen geneettisten algoritmien osalla, joten tuloksia voidaan verrata. Lopuksi tutkittiin pienen muuttuvanopeuksisella pumpulla syötetyn vesijohtoverkoston toimintaa. Esitetyt menetelmät perustuvat ominaisenergiankulutuksen minimointiin. Saatuja tuloksia verrataan korkearesoluutioisella diskreetillä dynaamisella ohjelmoinnilla saatuihin tuloksiin. Työssä kehitettiin uusia optimointitekniikoita vedenjakelujärjestelmien pumppauksen aikataulutuksen optimintiin. Erityisesti työssä keskityttiin pumppauksen, vesitornien ja kuluttajien käyttäytymisen väliseen dynamiikkaan. Työssä osoitettiin tekniikoiden toimivuus realististen esimerkkisimulointien avulla
Kivonat Jelen doktori disszertáció regionális ivóvízellátó-hálózatok üzemvitel-optimalizációjával foglalkozik. A bemutatott módszerek alkalmazhatósági köre rendszerint eltér egymástól, mindegyik egy-egy speciális, de a való életben is előforduló problémára kíván megoldást nyújtani. A kidolgozott módszerek a medencék tárolókapacitását kihasználva, az optimális szivattyú-menetrendet keresve kívánják megtalálni az adott vízműhálózat üzemviteloptimumát. Az optimalizáció egy időben diszkrét, ugyanakkor determinisztikus feladat megoldását igényli, a vízfogyasztások sztochasztikus viselkedését a várható értékekkel közelítettem. Elsőként egy új mellékfeltétel-kezeléssel ellátott, ún. neutrális genetikus algoritmus bemutatása a cél. A kidolgozott módszer alkalmas nagy, valós méretű (pl. Budapest) és bonyolultságú (kapcsolt hidraulikai szimulációk, frekvenciaváltós és direkt szivattyúk a hálózatban) ivóvízhálózatok napi üzemvitel optimalizálására. Az eredményeket más genetikus algoritmusokkal és a világ élvonalába tartozó, de általános célú optimalizációs módszerekkel hasonlítottam össze. Kidolgozásra került egy dinamikus programozás alapú, a valós, globális optimumot adó módszer is. Az algoritmus a gyakorlatban elterjedt, ún. "kombinációs" hálózatként modellezhető vízműhálózat típusokra alkalmazható, ahol a szivattyúk munkapontjai diszkrét értékek. A megoldás alapját az ún. "permutációs invariancia" jelensége adja, mely lehetővé teszi az állapottér információveszteség nélküli, tökéletes diszkretizációját. Egy, a korábban bemutatott genetikus algoritmuséhoz hasonló problémakört megoldó, de közelítő dinamikus programozás alapú módszer is bemutatásra kerül. Az algoritmus a hálózat kisebb részegységekre (víztermelő területekre és fő elosztó hálózatra) való felbontásával és a fő elosztó hálózat állapotterének önkényes, de a megoldás jóságán jelentősen nem rontó csökkentésével éri el a program futtatásához szükséges számítási igény csökkentését. A tesztfeladatok egy része megegyezik a genetikus algoritmus tesztfeladataival, így azok közvetlenül összehasonlíthatóak. Végül bemutatásra kerül egy kisméretű, mindössze egy darab változtatható fordulat- számú szivattyúval táplált rendszer energetikai vizsgálata. Az itt bemutatott módszerek mind a fajlagos energiafelhasználás minimalizálásán alapulnak. Az eredményeket egy nagyfelbontású dinamikus programozás alapú módszerhez hasonlítottam
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Hoskins, Asher John. "Monitoring the hydraulic dynamics in water distribution systems." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/58335.
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Mankind has used pressurised pipes to deliver water over long distances for twenty five centuries and yet the importance of their dynamic hydraulic behaviour on extending the life cycle of critical assets remains poorly understood. This project has developed a novel architecture for collecting, storing, and analysing the dynamic hydraulic behaviour of water distribution systems. This architecture was used to build an extensive collection of dynamic hydraulic pressure recordings which enabled a wide ranging analysis of the effect of pressure transients upon the performance of distribution system assets. A framework, "Dynamic Data Driven Transient Analysis" (D3TA), was developed to detect network state, transient or non-transient flow conditions, to count transients, and to explore the correlation between dynamic hydraulic behaviour and system failures. The effect of calming networks, removing and minimising transient behaviour, was shown to result in a significant potential reduction in bursts. This project has revealed that the hydraulic conditions in distributions systems are rarely steady state and that hydraulic transients are both frequent and potentially damaging. The algorithms and framework developed in this project have the ability to automatically diagnose and identify network areas at risk of damage as a result of their unsteady-state hydraulic behaviour. This would allow water utilities to proactively identify and repair the sources of hydraulic instabilities in operational networks and maintain "calm" networks, thus reducing costs and extending the working lifetimes of network assets. The results show that in some systems a reduction of the dynamic behaviour could result in a significant (10-20%) reduction in bursts.
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Hoagland, Steven. "TRANSIENT-BASED RISK ANALYSIS OF WATER DISTRIBUTION SYSTEMS." UKnowledge, 2016. http://uknowledge.uky.edu/ce_etds/39.
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Water distribution system utilities must be able to maintain a system’s assets (i.e., pumps, tanks, water mains, etc.) in good working condition in order to provide adequate water quantity and quality to its customers. Various asset management approaches are employed by utilities in order to make optimal decisions regarding the renewal of system components. Part of a good asset management approach is performing a comprehensive risk analysis which consists of considering all potential ways in which the system may fail, the likelihood failure of for each scenario, and the consequences of said failure. This study investigates a water distribution system’s risk of failure due to both acute transient events (e.g., pump trip) and standard pressure fluctuations due to daily system operations. Such an analysis may be useful in optimal decision making such as asset monitoring, scheduling of condition assessments or system renewal projects, policy implementation, and investment priorities in order to keep the utility’s total costs at a minimum. It may also be useful as a precautionary measure to help prevent catastrophic failures such as large main blowouts for which the utility would incur substantial costs, both direct and indirect.
As part of this thesis, a database of water distribution system models is used to analyze the effects of an acute transient event for different system configurations. The database was created at the University of Kentucky and has been made available to the research community to test newly developed algorithms for various studies including optimal system operations and optimal system design.
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Novak, Julia Ann. "Cavitation and Bubble Formation in Water Distribution Systems." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/42435.
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Gaseous cavitation is examined from a practical and theoretical standpoint. Classical cavitation experiments which disregard dissolved gas are not directly relevant to natural water systems and require a redefined cavitation inception number which considers dissolved gases. In a pressurized water distribution system, classical cavitation is only expected to occur at extreme negative pressure caused by water hammer or at certain valves. Classical theory does not describe some practical phenomena including noisy pipes, necessity of air release valves, faulty instrument readings due to bubbles, and reports of premature pipe failure; inclusion of gaseous cavitation phenomena can better explain these events. Gaseous cavitation can be expected to influence corrosion in water distribution pipes.
Bubbles can form within the water distribution system by a mechanism known as gaseous cavitation. A small scale apparatus was constructed to track gaseous cavitation as it could occur in buildings. Four independent measurements including visual observation of bubbles, an inline turbidimeter, an ultrasonic flow meter, and an inline total dissolved gas probe were used to track the phenomenon. All four measurements confirmed that gaseous cavitation was occurring within the experimental distribution system, even at pressures up to 40 psi. Gaseous cavitation was more likely at higher initial dissolved gas content, higher temperature, higher velocity and lower pressure. Certain changes in pH, conductivity, and surfactant concentration also tended to increase the likelihood of cavitation. For example, compared to the control at pH 5.0 and 30 psig, the turbidity increased 295% at pH 9.9. The formation of bubbles reduced the pumpâ s operating efficiency, and in the above example, the velocity was decreased by 17% at pH 9.9 versus pH 5.0.Master of Science
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Chen, Jinduan. "Stochastic Demand-hydraulic Model of Water Distribution Systems." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439301579.
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Zhong, Qinghui. "Optimal operations of large scale water distribution systems." Diss., The University of Arizona, 1994. http://hdl.handle.net/10150/187025.
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Improving water distribution system operations can be achieved through the use of optimally generated pump schedules by minimizing the overall pumping cost while satisfying the water pressure and flow requirements and subject to all physical constraints. This study is devoted to developing a general methodology to determine the optimal operations of large scale water distribution systems. Rather than solving the original mixed integer nonlinear programming problem directly, a two-level hierarchical optimization scheme is proposed. The first level is a NLP problem where the decision variables are each pump station's discharge and added head, pump speeds, valve control settings, nodal pressure heads and tank water elevations. At the second level a simple DP or a direct conversion method is applied to find the best pump combinations based on the optimal solutions obtained from the first level NLP optimization. Prior to solving the two level optimization problem, pre-optimization work is performed which produces a lumped energy function for each pump station to approximate the relationship between consumed energy and pump station's added head and discharge. To make the first level NLP problem solvable, a reduction technique is proposed which uses the network simulation model to reduce the number of constraints and decision variables. This reduction, however, results in a NLP problem with implicit decision variables which are not directly controlled by the decision variables. One strategy proposed is to consider the constraints of the implicit decision variables in a penalty term appended to the objective function. The problem is then structured using an augmented Lagrangian algorithm and solved with a NLP code. The second strategy is to use an active set method. The entire NLP problem is solved using successive quadratic programming where only the active constraint set is considered during the solution process of each quadratic programming subproblem. Two case studies were performed to determine the optimal schedules and compare the two NLP approaches. The Lagrangian seemed to perform better when many constraints were initially violated, while the active set method seemed appropriate to solve systems with few initial active constraints.
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Kang, Doo Sun. "Real-Time Demand Estimation for Water Distribution Systems." Diss., The University of Arizona, 2008. http://hdl.handle.net/10150/193614.
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The goal of a water distribution system (WDS) is to supply the desired quantity of fresh water to consumers at the appropriate time. In order to properly operate a WDS, system operators need information about the system states, such as tank water level, nodal pressure, and water quality for the system wide locations. Most water utilities now have some level of SCADA (Supervisory Control and Data Acquisition) systems providing nearly real-time monitoring data. However, due to the prohibitive metering costs and lack of applications for the data, only portions of systems are monitored and the use of the SCADA data is limited. This dissertation takes a comprehensive view of real-time demand estimation in water distribution systems. The goal is to develop an optimal monitoring system plan that will collect appropriate field data to determine accurate, precise demand estimates and to understand their impact on model predictions. To achieve that goal, a methodology for real-time demand estimates and associated uncertainties using limited number of field measurements is developed. Further, system wide nodal pressure and chlorine concentration and their uncertainties are predicted using the estimated nodal demands. This dissertation is composed of three journal manuscripts that address these three key steps beginning with uncertainty evaluation, followed by demand estimation and finally optimal metering layout.The uncertainties associated with the state estimates are quantified in terms of confidence limits. To compute the uncertainties in real-time alternative schemes that reduce computational efforts while providing good statistical approximations are evaluated and verified by Monte Carlo simulation (MCS). The first order second moment(FOSM) method provides accurate variance estimates for pressure; however, because of its linearity assumption it has limited predictive ability for chlorine under unsteady conditions. Latin Hypercube sampling (LHS) provides good estimates of prediction uncertainty for chlorine and pressure in steady and unsteady conditions with significantly less effort.For real-time demand estimation, two recursive state estimators; tracking state estimator (TSE) based on weighted least squares (WLS) scheme and Kalman filter (KF), are applied. In addition, in order to find available field data types for demand estimation, comparative studies are performed using pipe flow rate and nodal pressure head as measurements. To reduce the number of unknowns and make the system solvable, nodes with similar user characteristics are grouped and assumed to have same demand pattern. The uncertainties in state variables are quantified in terms of confidence limits using the approximate methods (i.e., FOSM and LHS). Results show that TSE with pipe flow rates as measurements provide reliable demand estimations. Also, the model predictions computed using the estimated demands match well with the synthetically generated true values.Field measurements are critical elements to obtaining quality real-time state estimates. However, the limited number of metering locations has been a significant obstacle for the real-time studies and identifying locations to best gain information is critical. Here, an optimal meter placement (OMP) is formulated as a multi-objective optimization problem and solved using a multi-objective genetic algorithm (MOGA) based on Pareto-optimal solutions. Results show that model accuracy and precision should be pursued at the same time as objectives since both measures have trade-off relationship. GA solutions were improvements over the less robust methods or designers' experienced judgment.
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Ferreira, Francisco Cardoso. "Chlorine dioxide and by-products in water distribution systems." Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-11242009-020052/.
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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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Bögershausen, Sebastian K. (Sebastian Karl Friedrich) 1973. "Architecture of near real-time monitoring systems for water distribution systems." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/84258.
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Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2001.Includes bibliographical references (leaf 73).
by Sebastian K. Bögershausen.
M.Eng.
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Chang, Tao. "Robust model predictive control of water quality in drinking water distribution systems." Thesis, University of Birmingham, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.398894.
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This thesis develops online feedback control of chlorine residuals performing at the lower level of a hierarchical structure of integrated quantity and quality control in drinking water distribution systems (DWDS), which provides a practical solution for online water quality control in DWDS. Input-output and state-space models of the chlorine residuals are developed from mathematical models of chlorine residual dynamics. The existing path analysis algorithm is extended and utilized to obtain the parameter structure. Joint parameter and model structure error estimation is developed using bounding approach based on a point-parametric model. The uncertainty radius of the system is outlined through robust output prediction, through which requirements for model accuracy from robust model predictive control (MFC) are explicitly imposed on model estimation. Hence, an integrated design of controller and model estimation is achieved. MFC is applied for chlorine residual control based on the set-bounded model. To fulfil output constraints under system uncertainties, safety zones are employed, which are designed from an online evaluation of the uncertainty scenarios of the system, to restrict the output constraints. The safety zones can be obtained by solving a nonlinear constrained optimization problem using a significantly simplified relaxation-gain algorithm. The resulting robust MFC (RMPC) is decentralized assuming communication among the decentralized RMPCs is available. The proposed methodology is verified by applying it to a simulated benchmark DWDS. Simulation study of model estimation and RMPC operation is presented and discussed.
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Liu, Li. "Real-time Contaminant Source Characterization in Water Distribution Systems." NCSU, 2009. http://www.lib.ncsu.edu/theses/available/etd-04122009-193753/.
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Accidental/intentional contamination continues to be a major concern for the security management in water distribution systems. Once a contaminant has been initially detected, an effective algorithm is required to recover the characteristics of the contaminantâs source based on dynamically varying streams of sensor observations. This dissertation focuses on the development and demonstration of a new algorithm to characterize a contaminant source quickly, accurately, and robustly. An evolutionary algorithm (EA)-based adaptive dynamic optimization technique (ADOPT) is proposed, potentially providing a real-time response. In addition to offering adaptive capacity in a dynamic environment, this algorithm is able to assess the degree of non-uniqueness in the solution through multi-population scheme. This approach, however, requires a large number of time-consuming simulation runs to evaluate possible solutions, and it may be difficult to converge on the best solution or a set of alternative solutions within a reasonable computational time. For this reason, it is desirable to appropriately reduce the decision space over which the optimization procedure must search to reduce the computational burden and to produce faster convergence. A logistic regression-based prescreening technique is investigated in order to reduce the decision space by estimating the probability of a node being a contaminant source location. When a small set of potential source nodes are identified, applying the local search procedure to this set of locations is computationally efficient and potentially good at identifying the best solution. The EA-based ADOPT is then integrated with a logistic regression analysis and a local improvement method to expedite the convergence and to solve the problem potentially faster. The effectiveness of the proposed methods is demonstrated for contamination source identification problems in two illustrative water distribution networks.
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Sreepathi, Sreerama (Sarat). "CYBERINFRASTRUCTURE FOR CONTAMINATION SOURCE CHARACTERIZATION IN WATER DISTRIBUTION SYSTEMS." NCSU, 2006. http://www.lib.ncsu.edu/theses/available/etd-12142006-011340/.
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Urban water distribution systems (WDSs) are vulnerable to accidental and intentional contamination incidents that could result in adverse human health and safety impacts. This thesis research is part of a bigger ongoing cyberinfrastructure project. The overall goal of this project is to develop an adaptive cyberinfrastructure for threat management in urban water distribution systems. The application software core of the cyberinfrastructure consists of various optimization modules and a simulation module. This thesis focuses on the development of specific middleware components of the cyberinfrastructure that enables efficient seamless execution of the core software component in a grid environment. The components developed in this research include: (i) a coarse-grained parallel wrapper for the simulation module that includes additional features for persistent execution and hooks to communicate with the optimization module and the job submission middleware, (ii) a seamless job submission interface, and (iii) a graphical real time application monitoring tool. The threat management problems used in this research is restricted to contaminant source characterization in water distribution systems.
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Mansour, Rezaei Fumani Saheb. "Contaminant intrusion in water distribution systems : advanced modelling approaches." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44042.
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Since exposure to contaminants may have direct adverse impacts on public health,
contaminant intrusion has been recognized as one of the top priority in drinking water supply
research. Three components must exist to cause contaminant intrusion into a water
distribution system. These include the availability of source(s) of contaminant(s) around a
water distribution system, the existence of driving forces (low/negative pressure) to make a
contaminant enter into a water distribution system, and the presence of pathway(s) through
which contaminant(s) intrude into a water distribution system (WDS). Exposure assessment
is the most challenging part as location of contaminant intrusion, rate of intrusion, and the
fate of contaminants within WDS need to be estimated accurately.
In this dissertation, first, common uncertainty analysis techniques are discussed in the context
of conservativeness, execution time, ease of formulation, and complexity. Second, a fuzzyrule
based model has been developed to identify contaminant intrusion potential in a WDS.
The potential of contaminant intrusion has been determined by integrating the potentials for
contaminant sources existence, driving forces, and pathways. Third, a novel ingress model
has been developed for more realistic estimation of intrusion rate by taking into account the
effects of surrounding soil on intrusion rate. Coupled with an Eulerian-based transient
hydraulic model, a Lagrangian transient water quality model is developed to predict the fate
of the contaminant throughout a WDS. The proposed models are applied to case studies
available in the literature to investigate the applicability of the models. The proposed models
enhance the reliability and safety of WDSs by improving the prediction ability of the existing
modelling tools.
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Xu, Chengchao. "Optimal operation and reliability evaluation of water distribution systems." Thesis, Heriot-Watt University, 1990. http://hdl.handle.net/10399/896.
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AbdelMeguid, Hossam Saadeldin. "Pressure, leakage and energy management in water distribution systems." Thesis, De Montfort University, 2011. http://hdl.handle.net/2086/4905.
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A fast and efficient method to calculate time schedules for internal and boundary PRVs and flow modulation curves has been developed and implemented. Both time and flow modulation can be applied to a single inlet DMA. The time modulation methodology is based on solving a nonlinear programming problem (NLP). In addition, Genetic Algorithms (GA) has been proposed and investigated to calculate the optimal coefficients of a second order relationship between the flow and the outlet pressure for a PRV to minimize the background leakage. The obtained curve can be subsequently implemented using a flow modulation controller in a feedback control scheme. The Aquai-Mod® is a hydraulic device to control and modulate the outlet pressure of a PRV according to the valve flow. The controller was experimentally tested to assess its performance and functionality in different conditions and operating ranges. The mathematical model of the controller has been developed and solved, in both steady state and dynamic conditions. The results of the model have been compared with the experimental data and showed a good agreement in the magnitude and trends. A new method for combined energy and pressure management via integration and coordination of pump scheduling with pressure control aspects has been created. The method is based on formulating and solving an optimisation NLP problem and involves pressure dependent leakage. The cost function of the optimisation problem represents the total cost of water treatment and pumping energy. Developed network scheduling algorithm consists of two stages. The first stage involves solving a continuous problem, where operation of each pump is described by continuous variable. Subsequently, the second stage continuous pump schedules are discretised using heuristic algorithm. Another area of research has been developing optimal feedback rules using GA to control the operation of pump stations. Each pump station has a rule described by two water levels in a downstream reservoir and a value of pump speed for each tariff period. The lower and upper water switching levels of the downstream reservoir correspond to the pump being “ON” or “OFF”. The achieved similar energy cost per 1 Ml of pumped water. In the considered case study, the optimal feedback rules had advantage of small number of ON/OFF switches, which increase the pump stations lifetime and reduce the maintenance cost as well.
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Seyoum, Alemtsehay Gebremeskel. "Head-dependent modelling and optimisation of water distribution systems." Thesis, University of Strathclyde, 2015. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=26007.
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Smart, Andrew C. "An investigation of the ecology of water distribution systems." Thesis, University of Leicester, 1989. http://hdl.handle.net/2381/34236.
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Animal infestations of water distribution systems are a cause of considerable concern for the water industry. The appearance of an animal at a consumer's tap often gives rise to complaints. This study, in Anglian Water, Oundle Division, Northamptonshire, U.K. investigated the ecology of the infesting community and its management. Mains sampling used sequential flushes at the hydrant and a model for animal removal was constructed. Tap sampling collected animals from filters at the tap and an index of emergence (density in a day's consumption) and degree of infestation (based on density and the ability to cause complaints) were devised. Reservoir sampling used a perspex trap to sample the water column and sediments. Methods to determine the environmental and operational characteristics of the system were also devised. Community clustering on the basis of animal density determined five distinct community types. Operational and environmental parameters did not coincide with any of the types, though correlations indicated that highest densities occurred at sites further (in time) from treatment with a low turnover time. Sites fed by slow sand filters were not recolonised by chironomid larvae nor to the degree of other sites by other taxa. No successional sequence was found and it was concluded that animals recolonised on the basis of a 'competitive lottery'. The relationship between density at the tap and in the main was considered and seasonal changes in the degree of infestation between sites confirmed that water from rapid gravity filtration leads to more severe animal problems, particularly during the summer. Benthic animals penetrated treatment in low numbers, but reservoirs near treatment were dominated by limnetic animals. Many died and became an indirect food source for infesting animals, but some survived and colonised pipes. Reservoirs at the extremes of the system were not influenced by these taxa and were 'extensions' of the distribution system.
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Ahn, Taejin. "Optimal design of municipal and irrigation water distribution systems." Diss., Virginia Tech, 1993. http://hdl.handle.net/10919/38649.
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In two-dimensional flow, the point of flow separation from the surface coincides with the point at which the skin friction vanishes. However, in three-dimensional flow, the situation is much more complex and the flow separation is rarely associated with the vanishing of the wall shear stress except in a few special cases. Though the effects of cross-plane separation are substantial and have been recognized for some time, the phenomenon of flow separation over three-dimensional bodies is still far from being completely understood. The flow is so complex that no completely satisfactory analytical tools are available at the moment. In an attempt to logically identify the various effects and parametric dependence while simultaneously minimizing configuration dependent issue, the flow over a 6 to 1 prolate spheroid, which is a generic three-dimensional body, is investigated.
For the identification of the general flow pattern and better understanding of the flow field, surface-oil-flow visualization tests and force and moment tests were performed. The angle of attack effect and Reynolds number effect on the separation location are studied with natural transition. Forces and moments tests, surface pressure distribution measurements as well as the surface pressure fluctuations, and mini-tuft flow visualization tests were made to document the flow characteristics on the surface of the body with an artificial boundary layer trip.Ph. D.
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Stathis, Jonathan Alexander. "A Model for Determining Leakage in Water Distribution Systems." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/46422.
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Leaks in pipe networks cause significant problems for utilities and water users in terms of lost revenue and interrupted service. In many cities the leakage is as high as forty percent. A water audit is carried out to assess system-wide leakage. However, to detect leakage at the level of a pipeline, a physical measurement technique is generally employed. For large cities the distribution piping length amounts to a few thousand miles. Therefore, the physical measurements can become tedious and expensive. In this thesis it is assumed that a spatial distribution of leakage can be estimated at nodes based on a water audit bookkeeping scheme. A mathematical formulation consisting of continuity, energy (headloss), pressure-dependent demands and/or leakage, and flow direction preservation equations are utilized to distribute demand flows and leakage among pipes. The leakage is attributed to the formation of corrosion holes. Based upon the extent of corrosion, the leakage flow arriving at a particular node is apportioned among all pipes that are converging at that node. Therefore, the formulation presented in this thesis captures the two essential elements behind leakage, namely, pressure driven flow distribution and the vulnerability of pipes to corrosion.
The proposed formulation allows utilities to be more proactive in identifying leakage prone districts within the water distribution system. An understanding of the pressure-dependent leakage in the system is helpful when performing a water audit and in developing strategies for leak repair programs. Restoring the full capacity of the water distribution system will greatly increase the reliability of the system, thereby benefiting local utilities and water users.Master of Science
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SUBRAMANIAM, PRATHIBA. "OPTIMAL LOCATIONS OF BOOSTER STATIONS IN WATER DISTRIBUTION SYSTEMS." University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1005757573.
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Mazumder, Ram Krishna. "Risk-Based Asset Management Framework for Water Distribution Systems." Case Western Reserve University School of Graduate Studies / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=case1594169243438607.
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Hampson, William J. "Locating sources of pressure transients in water distribution systems." Thesis, University of Sheffield, 2014. http://etheses.whiterose.ac.uk/5841/.
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Telci, Ilker Tonguc. "Optimal water quality management in surface water systems and energy recovery in water distribution networks." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45861.
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Two of the most important environmental challenges in the 21st century are to protect the quality of fresh water resources and to utilize renewable energy sources to lower greenhouse gas emissions. This study contributes to the solution of the first challenge by providing methodologies for optimal design of real-time water quality monitoring systems and interpretation of data supplied by the monitoring system to identify potential pollution sources in river networks. In this study, the optimal river water quality monitoring network design aspect of the overall monitoring program is addressed by a novel methodology for the analysis of this problem. In this analysis, the locations of sampling sites are determined such that the contaminant detection time is minimized for the river network while achieving maximum reliability for the monitoring system performance. The data collected from these monitoring stations can be used to identify contamination source locations. This study suggests a methodology that utilizes a classification routine which associates the observations on a contaminant spill with one or more of the candidate spill locations in the river network. This approach consists of a training step followed by a sequential elimination of the candidate spill locations which lead to the identification of potential spill locations. In order to contribute the solution of the second environmental challenge, this study suggests utilizing available excess energy in water distribution systems by providing a methodology for optimal design of energy recovery systems. The energy recovery in water distribution systems is possible by using micro hydroelectric turbines to harvest available excess energy inevitably produced to satisfy consumer demands and to maintain adequate pressures. In this study, an optimization approach for the design of energy recovery systems in water distribution networks is proposed. This methodology is based on finding the best locations for micro hydroelectric plants in the network to recover the excess energy. Due to the unsteady nature of flow in water distribution networks, the proposed methodology also determines optimum operation schedules for the micro turbines.
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Guc, Gercek. "Optimization Of Water Distribution Networks Using Genetic Algorithm." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607192/index.pdf.
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This study gives a description about the development of a computer model, RealPipe, which relates genetic algorithm (GA) to the well known problem of least-cost design of water distribution network.
GA methodology is an evolutionary process, basically imitating evolution process of nature. GA is essentially an efficient search method basically for nonlinear optimization cases. The genetic operations take place within the population of chromosomes. By means of various operators, the genetic knowledge in chromosomes change continuously and the success of the population progressively increases as a result of these operations. GA optimization is also well suited for optimization of water distribution systems, especially large and complex systems. The primary objective of this study is optimization of a water distribution network by GA. GA operations are realized on a special program developed by the author called RealPipe. RealPipe optimizes given water network distribution systems by considering capital cost of pipes only.
Five operators are involved in the program algorithm. These operators are generation, selection, elitism, crossover and mutation. Optimum population size is found to be between 30-70 depending on the size of the network (i.e. pipe number) and number of commercially available pipe size. Elitism rate should be around 10 percent. Mutation rate should be selected around 1-5 percent depending again on the size of the network. Multipoint crossover and higher rates are advisable. Also pressure penalty parameters are found to be much important than velocity parameters. Below pressure penalty parameter is the most important one and should be roughly 100 times higher than the other.
Two known networks of the literature are examined using RealPipe and expected results are achieved. N8.3 network which is located in the northern side of Ankara is the case study. Total cost achieved by RealPipe is 16.74 percent lower than the cost of the existing networkit should be noted that the solution provided by RealPipe is hydraulically improved.
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Cox, Deborah P. "Analysis of privatization of the Jacksonville MIlitary Complex's potable water distribution systems." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1996. http://handle.dtic.mil/100.2/ADA324177.
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Thesis (M.S. in Management) Naval Postgraduate School, December 1996.Thesis advisor(s): James Fremgen, Janice M. Menker. "december 1996." Includes bibliographical references (p. 73-75). Also available online.