Dissertations / Theses on the topic 'Water distribution system design optimization'
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1
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.
2
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.
3
Xie, Xiongfei. "Operation Optimization and Water Quality Simulation of Potable Water Distribution System." Scholar Commons, 2014. https://scholarcommons.usf.edu/etd/5406.
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A potable water distribution system (WDS) consists of pipes, pumps, valves, storage tanks, control and supporting components. Traditionally, it has two basic functions. First, provides end users with potable water at sufficient pressures and good water quality. Second, provides sufficient pressure and flow for fire fighting. Currently, potable water is still the least expensive material for fire fighting. To accomplish these two goals, water utilities have to consider the integrity and security of the water network. As a result, this research selected three research topics that are closely related to the daily operation of water utilities and water quality simulation.
The first study is on optimal sampling design for chlorine decay model calibration. Three questions are investigated: (1) What is the minimum number of chlorine sample locations a water network needs? (2) How many combinations of sampling locations are available? (3) What is the optimal location combination? To answer the first two questions, the mathematical expressions of the chlorine concentrations between any two sampling locations are developed and sampling point relationship matrices are generated, then a mixed integer programming (MIP) algorithm is developed. Once obtained, the solutions to the first two questions are used to calculate the chlorine decay wall reaction coefficients and sensitivity matrix of chlorine concentration wall reaction coefficients; then, sampling location combinations achieved in the second question are sorted using a D-optimality algorithm. The model frame is demonstrated in a case study. The advantage of this method, compared to the traditional iterative sensitivity matrix method, is that a prior knowledge or estimation of wall reaction coefficients is not necessary.
The second study is on optimizing the operation scheduling of automatic flushing device (AFD) in water distribution system. Discharging stagnant water from the pipeline through AFD is a feasible method to maintain water quality. This study presents a simulation-based optimization method to minimize total AFD discharge volume during a 24-hour horizon. EPANET 2.0 is used as hydraulics and water quality simulator. This is formulated as a single objective optimization problem. The decision variables are the AFD operation patterns. The methodology has three phases. In the first phase, AFD discharge capacities are calculated, whether existing AFDs are able to maintain chlorine residuals in the water network is also evaluated. In the second phase, the decision variables are converted to AFD discharge rates. A reduced gradient algorithm is used to quickly explore and narrow down the solution space. At the end of this phase, decision variables are switched back to the AFD operation patterns. In the third phase, simulated annealing is used to search intensively to exploit the global minimum. The method is demonstrated on the water system located at the south end of Pinellas County, Florida where AFD optimal operation patterns are achieved.
The third study is on simulating contaminant intrusion in water distribution system. When contaminant matrix is introduced into water distribution system, it reacts with chlorine in bulk water rapidly and causes fast disinfectant depletion. Due to the difficulties in identifying contaminant types and chemical and biological properties, it is a challenging task to use EPANET-MSX to simulate chlorine decay under contaminant attack. EPANET 2.0 is used in the study to accomplish this goal. However, EPANET 2.0 cannot directly simulate chlorine depletion in the event of contamination attack because it assigns one time-independent bulk reaction coefficient to one specific pipe during the simulation. While under contaminant intrusion, chlorine decay bulk coefficient is not a constant. Instead, it is a temporal and spatial variable. This study presents an innovative approach for simulating contaminant intrusion in water distribution systems using EPANET multiple times. The methodology has six general steps. First, test bulk reaction coefficients of contaminant matrix in chemical lab. The uniqueness of this study is that the contaminant matrix is studied as a whole. The investigations of chemical, biological properties of individual aqueous constituents are not needed. Second, assume the contaminants as nonreactive, using EPANET 2.0 to identify where, when and at what concentrations of the inert contaminants will pass by in the water network. Third, determine the number of chlorine residual simulations based on the results in step two. Fourth, use EPANET to simulate the chlorine residual in the water network without the occurrence of contamination. Fifth, assign contaminated bulk coefficients to contaminated pipes; use EPANET to simulate the chlorine residual in the pipe network. Lastly, the chlorine concentrations of the impacted moments of impacted junctions are replaced with the results calculated in step five. This methodology is demonstrated in the south Pinellas County water distribution system.
4
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.
5
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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Siew, Calvin Yew Ming. "A penalty-free multi-objective evolutionary optimization approach for the design and rehabilitation of water distribution systems." Thesis, University of Strathclyde, 2011. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=25978.
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As a result of the increasing emphasis placed on water companies to conform to the stringent performance standards in supplying demands within a constrained financial budget, the application of optimization has inevitably become an integral part of managing a water distribution system (WDS) right from the initial phase of designing a new system to the latter stage of the network where rehabilitation and upgrading works are a necessity. This also includes the on-going operation of the WDS in particular the minimization of energy costs related to pumping and storage. This thesis is concerned with the development and application of a new multi-objective genetic algorithm in optimizing the design, operation and long term rehabilitation and upgrading of the WDS.The novelty and originality of the work done as part of this research are presented next. A seamless, augmented version of the renowned EPANET 2 with pressure dependent analysis (PDA) functionality has been developed. It integrates within the hydraulic engine a continuous nodal pressure-flow function coupled with a line search and backtracking procedure which greatly enhances the algorithm’s overall convergence rate and robustness. The hydraulic simulator is termed “EPANET-PDX” (pressure-dependent extension) herein and is capable of effectively modelling networks under pressure deficient situations which the demand driven analysis based EPANET 2 fails to accurately analyse. In terms of computational efficiency, the performance of EPANET-PDX compares very favourably to EPANET 2. Simulations of real life networks consisting of multiple sources, pipes, valves and pumps were successfully executed with no convergence complications. The simulator depicts excellent modelling performance while analysing both normal and abnormal operating conditions of the WDSs. The accuracy of the generated PDA results has been explicitly validated and verified. An optimization model for the optimal design and upgrading of WDS involving both the operation of multiple pumps and the sizing and location of multiple tanks is developed. The model couples a new boundary convergent multi-objective genetic algorithm to the highly efficient EPANET-PDX simulator which, inherently,automatically accounts for the node pressure constraints as well as the conservation of mass and energy. With accurate PDA, the direct application of the standard extended period simulation enables pump scheduling and tank sizing and siting to be seamlessly incorporated into the optimization without the need for any extraneous methodology or manual intervention. The significant advantage of this model is that it eliminates the need for ad-hoc penalty functions, additional “boundary search” parameters, or special constraint handling procedures. No operator intervention, parameter calibration and trial runs are required. Conceptually, the approach is straightforward and probably the simplest hitherto. The model is applied to several benchmark networks yielding superior results in terms of the initial network construction cost and the number of hydraulic simulations required. The above-mentioned optimization model is extended to form a module for the optimal long term design, upgrading and rehabilitation of WDSs. The multi-criteria problem is set up in a multi-objective frame work i.e. to minimize the capital cost,rehabilitation and upgrading costs, whilst maximizing the network hydraulic performance. A straightforward approach for incorporating reliability measures without further complicating the optimization formulation is utilised and its robustness validated. The effect of deterioration of both the structural integrity and hydraulic capacity of pipes over time is explicitly modelled. The model automatically determines the most cost effective strategy which includes the identification of pipes to be upgraded, the upgrading or rehabilitation options and the timing for the upgrade to be implemented. A real life network in Wobulenzi (Uganda) is used to demonstrate the effectiveness of the model. Results obtained demonstrated major improvements over previous work using the classical linear programming.
7
Zanoli, Sara. "A modularity based approach and high-level flow model in the optimal design of water distribution networks using a Genetic Heritage Evolution (GHEST) algorithm." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
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In order to reduce the environmental load and the shortage in fresh water supply, recent studies have focused in establishing rules for a green and sustainable development or redesign of cities. As far as water issues are concerned, the role of infrastructure is commonly recognized as one of the main driver in determining the environmental results. Compared to other infrastructures, modern Water Distribution Systems suffer from a more important structural delay that is nowadays producing criticalities and issues in their everyday functioning. WDNs represent the most complex and main infrastructure for the transportation of clean drinking water from reservoirs and storage tanks to industrial and residential consumers. In order to satisfy consumers demand, WDNs must be constructed with a good layout that connects all points of water demand and should provide the best possible hydraulic conditions and operational requirements, minimizing network costs. This is known as the WDN design problem. In an attempt to resolve the optimization of real WDN problem, Information and Communication Technologies and Optimization Algorithms have been exploited. In this context, the aim of this master thesis is to propose the application of new methodologies to the optimal design of WDNs that include the employment of a Graph-theory, a modularity based approach and the concept of High-level flow, employed in order to simplify the WDN complexity before the optimization process. GHEST algorithm is exploited in order to deal the optimal design problem. The methodologies were applied to DTown and ModenaS networks, both already known in literature.
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Barr?to, J?nior Manoel. "Otimiza??o de um sistema de distribui??o predial de ?gua fria: estudo de caso." Universidade Federal do Rio Grande do Norte, 2006. http://repositorio.ufrn.br:8080/jspui/handle/123456789/16019.
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Previous issue date: 2006-12-21This dissertation presents a methodology to the optimization of a predial system of cold water distribution. It s about a study of a case applied to the Tropical Buzios Residential Condominium, located in the B?zio s Beach, N?sia Floresta city, the east coast of the Rio Grande do Norte state, twenty kilometers far from Natal. The design of cold water distribution networks according to Norm NBR 5626 of the ABNT - Brazilian Association of Techniques Norms, does not guarantee that the joined solution is the optimal solution of less cost. It s necessary the use of an optimization methodology, that supplies us, between all the possible solutions, the minimum cost solution. In the optimization process of the predial system of water distribution of the Tropical B?zios Condominium, is used Method Granados, that is an iterative algorithm of optimization, based on the Dynamic Programming, that supplies the minimum cost s network, in function of the piezometric quota of the reservoir. For the application of this Method in ramifies networks, is used a program of computer in C language. This process is divided in two stages: attainment of the previous solution and reduction of the piezometric quota of headboard. In the attainment of the previous solution, the minors possible diameters are used that guarantee the limit of maximum speed and the requirements of minimum pressures. The piezometric quota of headboard is raised to guarantee these requirements. In the second stage of the Granados Method, an iterative process is used and it objective is to reduce the quota of headboard gradually, considering the substitution of stretches of the network pipes for the subsequent diameters, considering a minimum addition of the network cost. The diameter change is made in the optimal stretch that presents the lesser Exchange Gradient. The process is locked up when the headboard quota of desired is reached. The optimized network s material costs are calculated, and is made the analysis of the same ones, through the comparison with the conventional network s costs
Esta Disserta??o apresenta uma metodologia para a otimiza??o de um sistema de distribui??o predial de ?gua fria. Trata-se de um estudo de caso aplicado ao Condom?nio Residencial B?zios Tropical, localizado na Praia de B?zios, munic?pio de N?sia Floresta, litoral leste do Estado do Rio Grande do Norte, distante vinte quil?metros de Natal. O dimensionamento de redes de distribui??o predial de ?gua fria segundo os crit?rios da Norma NBR 5626 da ABNT - Associa??o Brasileira de Normas T?cnicas, n?o garante que a solu??o encontrada seja a solu??o ?tima de menor custo. ? necess?ria a utiliza??o de uma metodologia para otimiza??o, que nos forne?a, entre todas as solu??es poss?veis, a solu??o de custo m?nimo. No processo de otimiza??o do sistema de distribui??o predial do Condom?nio B?zios Tropical, ? utilizado o M?todo Granados, que ? um algoritmo iterativo de otimiza??o, baseado na Programa??o Din?mica, que fornece a rede de custo m?nimo, em fun??o da cota piezom?trica do reservat?rio. Para a aplica??o desse M?todo a redes ramificadas, ? utilizado um programa de computador em linguagem C. Esse processo ? dividido em duas etapas: obten??o da solu??o pr?via e redu??o da cota piezom?trica de cabeceira. Na obten??o da solu??o pr?via s?o utilizados os menores di?metros poss?veis que garantam o limite de velocidade m?xima e os requisitos de press?es m?nimas. A cota piezom?trica de cabeceira ? elevada ficticiamente para garantir esses requisitos. Na segunda etapa do M?todo Granados ? utilizado um processo iterativo, cujo objetivo ? reduzir gradualmente a cota de cabeceira, considerando a substitui??o de trechos da tubula??o da rede pelos di?metros subseq?entes, considerando um acr?scimo m?nimo de custo para a rede. A mudan?a de di?metro ? feita no trecho ?timo que apresenta o menor Gradiente de C?mbio. O processo se encerra quando ? atingida a cota de cabeceira desejada. S?o calculados os custos com materiais da rede otimizada e feita a an?lise dos mesmos, atrav?s da compara??o com os custos da rede convencional
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Formiga, Klebber Teodomiro Martins. "Otimização multiobjetivo de projetos de redes de distribuição de água." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-29012016-125410/.
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O dimensionamento otimizado de sistemas de distribuição de águas tem originado centenas de trabalhos científicos nas últimas quatro décadas. Vários pesquisadores têm buscado encontrar uma metodologia capaz de dimensionar essas redes considerando diversos aspectos e incertezas características desse tipo de projeto. No entanto, os resultados da maioria das metodologias desenvolvidas não podem ser aplicados na prática. O objetivo deste trabalho é elaborar uma metodologia de dimensionamento de redes de distribuição de água considerando um enfoque multiobjetivo. A metodologia desenvolvida considera três aspectos referentes ao projeto desses sistemas: custo; confiabilidade e perdas por vazamentos. Para tanto, empregou-se um método de otimização multiobjetivo baseado em algoritmos genéticos para a geração do conjunto de soluções não-dominadas e um método multicriterial para escolha da alternativa final. Para representar os objetivos do problema, foram testadas nove funções: custo, vazamentos, entropia, resiliência, tolerância à falha, expansibilidade, efeito do envelhecimento e resilientropia, sendo que sete destas são específicas para a representação da confiabilidade. Para se avaliar as alternativas geradas foi desenvolvido um modelo de análise hidráulica que fosse capaz de trabalhar com vazamentos e com demandas dependente da pressão. Os métodos escolhidos foram o Híbrido de Nielsen e o Gradiente. Das funções testadas, a resilientropia, proposta originalmente neste trabalho, foi a que melhor se ajustou ao conceito formal de confiabilidade, representado pela função tolerância. Os resultados encontrados pela metodologia mostraram-se promissores, uma vez esta foi capaz de encontrar redes eficientes ao final das simulações.The topic \"Optimized design of water distribution systems\" has generated hundreds of scientific publications in the last four decades. Several researchers have searched for a technology which would take into account a variety of aspects and uncertainties innate to the design of such networks. However, the results of most methodologies developed are not practical. The objective of this work is to develop a methodology for water distribution systems design that has a multi-objective focus. The methodology developed focuses in three aspects of the design of such systems: cost, reliability and losses by leaking. A multiobjective optimization method based on generic algorithms, generating a set of non-defined solutions, and a multi-criteria method for choosing the final alternative, was employed. Nine functions representing the objectives of the problem (method) were tested: cost, leakages, entropy, resilience, failure tolerance, expansibility, aging effect and resilienthropy, seven of which are specific to representing reliability. In order to evaluate the generated alternatives, a hydraulic analysis model, that could handle leakages and pressure dependent demands, was developed. The chosen methods were Nielsen\'s Hybrid, and the Gradient. Of all tested functions, resilientropy, originally proposed in this work, proved to be the one best adjusted to the formal concept of reliability, represented by the tolerance function. The results obtained by this methodology are promising, as they produced efficient distribution networks at the end of the simulations performed.
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DEKHANE, NIKHIL GOVIND. "DISTRIBUTION SYSTEM DESIGN USING OPTIMIZATION APPROACH." University of Cincinnati / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1092334088.
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Setiadi, Yohan. "Entropy-based design optimization of water distribution networks." Thesis, University of Liverpool, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.433064.
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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.
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Basupi, Innocent. "Adaptive water distribution system design under future uncertainty." Thesis, University of Exeter, 2013. http://hdl.handle.net/10871/14722.
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A water distribution system (WDS) design deals with achieving the desired network performance. WDS design can involve new and / or existing network redesigns in order to keep up with the required service performance. Very often, WDS design is expensive, which encourages cost effectiveness in the required investments. Moreover, WDS design is associated with adverse environmental implications such as greenhouse gas (GHG) emissions due to energy consumption. GHGs are associated with global warming and climate change. Climate change is generally understood to cause reduction in water available at the sources and increase water demand. Urbanization that takes into account factors such as demographics (population ageing, household occupancy rates, etc.) and other activities are associated with water demand changes. In addition to the aforementioned issues, the challenge of meeting the required hydraulic performance of WDSs is worsened by the uncertainties that are associated with WDS parameters (e.g., future water demand). With all the factors mentioned here, mitigation and adaptive measures are considered essential to improve WDS performance in the long-term planning horizon. In this thesis, different formulations of a WDS design methodologies aimed at mitigating or adapting the systems to the effects of future changes such as those of climate change and urbanization are explored. Cost effective WDS designs that mitigate climate change by reducing GHG emissions have been investigated. Also, water demand management (DM) intervention measures, i.e., domestic rainwater harvesting (RWH) systems and water saving appliance schemes (WSASs) have been incorporated in the design of WDSs in an attempt to mitigate, adapt to or counteract the likely effects of future climate change and urbanization. Furthermore, flexibility has been introduced in the long-term WDS design under future uncertainty. The flexible methodology is adaptable to uncertain WDS parameters (i.e., future water demand in this thesis) thereby improving the WDS economic cost and hydraulic performance (resilience). The methodology is also complimented by strategically incorporating DM measures to further enhance the WDS performance under water demand uncertainty. The new methodologies presented in this thesis were successfully tested on case studies. Finally, conclusions and recommendations for possible further research work are made. There are potential benefits (e.g., cost savings, additional resilience, and lower GHG emissions) of incorporating an environmental objective and DM interventions in WDS design. Flexibility and DM interventions add value in the design of WDSs under uncertainty.
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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.
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Kapelan, Zoran. "Calibration of water distribution system hydraulic models." Thesis, University of Exeter, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370011.
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A number of mathematical models are used nowadays to describe behaviour of the reallife water distribution system (WDS). It is a well known fact that, to have any meaningful use, any WDS mathematical model must be calibrated first. Here, calibration is defined as process in which a number of WDS model parameters are adjusted until the model mimics behaviour of the real WDS as closely as possible. In this thesis, WDS mathematical models that are used to model water quantity aspect only are analysed. Three hydraulic models considered here are: (1) steady-state flow model, (2) quasi-steady flow (extended period simulation) model and (3) unsteady flow model. The calibration problem analysed here is formulated as a constrained optimisation problem of weighted least square type with the objective defined in a way that enables effective incorporation of prior information on calibration parameters. WDS calibration problem is then analysed in detail, including special issues of identifiability, uniqueness and stability of the problem solution. A list of diagnostic and other statistics and analysis is presented to improve existing calibration approaches by providing partial insight into the calibration process. Calibration of WDS hydraulic models is further improved by the development of new hybrid optimisation method. Being closely related to calibration, the problem of sampling design for calibration of WDS hydraulic models is also addressed here. First, sampling design is formulated as a constrained two-objective optimisation problem. Then, two novel models are developed to solve it. The first model is based on standard, single-objective Genetic Algorithms (SOGA). The second model is based on multi-objective Genetic Algorithms (MOGA). Finally, all novel methodologies presented here are verified successfully on multiple case studies that involve both artificial and real-life WDS. At the end, relevant conclusions are drawn and suggestions for further research work are made.
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Chung, Gunhui. "Water Supply System Management Design and Optimization under Uncertainty." Diss., The University of Arizona, 2007. http://hdl.handle.net/10150/195506.
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Increasing population, diminishing supplies and variable climatic conditions can cause difficulties in meeting water demands. When this long range water supply plan is developed to cope with future water demand changes, accuracy and reliability are the two most important factors. To develop an accurate model, the water supply system has become more complicated and comprehensive structures. Future uncertainty also has been considered to improve system reliability as well as economic feasibility.In this study, a general large-scale water supply system that is comprised of modular components was developed in a dynamic simulation environment. Several possible scenarios were simulated in a realistic hypothetical system. In addition to water balances and quality analyses, construction and operation of system components costs were estimated for each scenario. One set of results demonstrates that construction of small-cluster decentralized wastewater treatment systems could be more economical than a centralized plant when communities are spatially scattered or located in steep areas.The Shuffled Frog Leaping Algorithm (SFLA), then, is used to minimize the total system cost of the general water supply system. Decisions are comprised of sizing decisions - pipe diameter, pump design capacity and head, canal capacity, and water/wastewater treatment capabilities - and flow allocations over the water supply network. An explicit representation of energy consumption cost for the operation is incorporated into the system in the optimization process of overall system cost. Although the study water supply systems included highly nonlinear terms in the objective function and constraints, a stochastic search algorithm was applied successfully to find optimal solutions that satisfied all the constraints for the study networks.Finally, a robust optimization approach was introduced into the design process of a water supply system as a framework to consider uncertainties of the correlated future data. The approach allows for the control of the degree of conservatism which is a crucial factor for the system reliabilities and economical feasibilities. The system stability is guaranteed under the most uncertain condition and it was found that the water supply system with uncertainty can be a useful tool to assist decision makers to develop future water supply schemes.
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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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Wen, Naijun. "Optimization of ship-pack in a two-echelon distribution system." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/61903.
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Thesis (S.M.)--Massachusetts Institute of Technology, Computation for Design and Optimization Program, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 61-62).
The traditional Economic Order Quantity (EOQ) model ignores the physical limitations of distribution practices. Very often distribution centers (DC) have to deliver merchandise in manufacturer-specified packages, which can impose restrictions on the application of the economic order quantity. These manufacturer-specified packages, or ship-packs, include cases (e.g., cartons containing 24 or 48 units), inners (packages of 6 or 8 units) and eaches (individual units). For each Stock Keeping Unit (SKU), a retailer decides which of these ship-pack options to use when replenishing its retail stores. Working with a major US retailer, we have developed a cost model to help determine the optimum warehouse ship-pack. Besides recommending the most economical ship-pack, the model is also capable of identifying candidates for warehouse dual-slotting, i.e., two picking modules for the same SKU that carry two different pack sizes. We find that SKUs whose sales volumes vary greatly over time will benefit more from dual-slotting. Finally, we extend our model to investigate the ideal case configuration for a particular SKU, that is, the ideal size for an inner package.
by Naijun Wen.
S.M.
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Bullene, Rachel. "A Case Study of Network Design for Middle East Water Distribution." VCU Scholars Compass, 2010. http://scholarscompass.vcu.edu/etd/2260.
Full textAbstract:
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.
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Bedoya, Ceballos Juan Carlos. "Optimization Methods for Distribution Systems: Market Design and Resiliency Enhancement." Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/99489.
Full textAbstract:
The increasing penetration of proactive agents in distribution systems (DS) has opened new possibilities to make the grid more resilient and to increase participation of responsive loads (RL) and non-conventional generation resources. On the resiliency side, plug-in hybrid electric vehicles (PHEV), energy storage systems (ESS), microgrids (MG), and distributed energy resources (DER), can be leveraged to restore critical load in the system when the utility system is not available for extended periods of time. Critical load restoration is a key factor to achieve a resilient distribution system. On the other hand, existing DERs and responsive loads can be coordinated in a market environment to contribute to efficiency of electricity consumption and fair electricity tariffs, incentivizing proactive agents' participation in the distribution system.
Resiliency and market applications for distribution systems are highly complex decision-making problems that can be addressed using modern optimization techniques. Complexities of these problems arise from non-linear relations, integer decision variables, scalability, and asynchronous information. On the resiliency side, existing models include optimization approaches that consider system's available information and neglect asynchrony of data arrival. As a consequence, these models can lead to underutilization of critical resources during system restoration. They can also become computationally intractable for large-scale systems. In the market design problem, existing approaches are based on centralized or computational distributed approaches that are not only limited by hardware requirements but also restrictive for active participation of the market agents.
In this context, the work of this dissertation results in major contributions regarding new optimization algorithms for market design and resiliency improvement in distribution systems. In the DS market side, two novel contribution are presented: 1) A computational distributed coordination framework based on bilateral transactions where social welfare is maximized, and 2) A fully decentralized transactive framework where power suppliers, in a simultaneous auction environment, strategically bid using a Markowitz portfolio optimization approach. On the resiliency side, this research proposed a system restoration approach, taking into account uncertain devices and associated asynchronous information, by means of a two-module optimization models based on binary programming and three phase unbalanced optimal power flow. Furthermore, a Reinforcement Learning (RL) method along with a Monte Carlo tree search algorithm has been proposed to solve the scalability problem for resiliency enhancement.Doctor of Philosophy
Distribution systems (DS) are evolving from traditional centralized and fossil fuel generation resources to networks with large scale deployment of responsive loads and distributed energy resources. Optimization-based decision-making methods to improve resiliency and coordinate DS participants are required. Prohibitive costs due to extended power outages require efficient mechanisms to avoid interruption of service to critical load during catastrophic power outages. Coordination mechanisms for various generation resources and proactive loads are in great need. Existing optimization-based approaches either neglect the asynchronous nature of the information arrival or are computationally intractable for large scale system. The work of this dissertation results in major contributions regarding new optimization methods for market design, coordination of DS participants, and improvement of DS resiliency. Four contributions toward the application of optimization approaches for DS are made: 1) A distributed optimization algorithm based on decomposition and best approximation techniques to maximize social welfare in a market environment, 2) A simultaneous auction mechanism and portfolio optimization method in a fully decentralized market framework, 3) Binary programming and nonlinear unbalanced power flow, considering asynchronous information, to enhance resiliency in a DS, and 4) A reinforcement learning method together with an efficient search algorithm to support large scale resiliency improvement models incorporating asynchronous information.
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Lan, Fujun. "Application of Optimization Techniques to Water Supply System Planning." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/323378.
Full textAbstract:
Water supply system planning is concerned about the design of water supply infrastructure for distributing water from sources to users. Population growth, economic development and diminishing freshwater supplies are posing growing challenges for water supply system planning in many urban areas. Besides the need to exploit alternative water sources to the conventional surface and groundwater supplies, such as reclaimed water, a systematic point of view has to be taken for the efficient management of all potential water resources, so that issues of water supply, storage, treatment and reuse are not considered separately, but rather in the context of their interactions. The focus of this dissertation is to develop mathematical models and optimization algorithms for water supply system planning, where the interaction of different system components is explicitly considered. A deterministic nonlinear programming model is proposed at first to decide pipe and pump sizes in a regional water supply system for satisfying given potable and non-potable user demands over a certain planning horizon. A branch-and-bound algorithm based on the reformulation-linearization technique is then developed for solving the model to global optimality. To handle uncertainty in the planning process, a stochastic programming (SP) model and a robust optimization (RO) model are successively proposed to deal with random water supply and demand and the risk of facility failure, respectively. Both models attempt to make the decision of building some additional treatment and recharge facilities for recycling wastewater on-the-site. While the objective of the SP model is to minimize the total system design and expected operation cost, the RO model tries to achieve a favorable trade-off between system cost and system robustness, where the system robustness is defined in terms of meeting given user demands against the worst-case failure mode. The Benders decomposition method is then applied for solving both models by exploiting their special structure.
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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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Sendil, Halil. "Operation Of Water Distribution Networks." Master's thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615484/index.pdf.
Full textAbstract:
With continuously increasing urbanization, consumer demands and expansion of water supply systems, determination of efficient pump schedules became a more difficult task. Pumping energy costs constitute a significant part of the operational cost of the water distribution networks. This study aims to provide an effective daily pump schedule by minimizing the energy costs for constant and also for multi tariff of electricity (3 Kademeli Elektrik Tarifesi) in water distribution network. A case study has been performed in an area covering N8.3 and N7 pressure zones which are parts of Ankara water distribution network. Both pressure zones consists of 3 multiple pumps in pump station and one tank having 5000 m3 storage volume each. By using genetic algorithm based software (WaterCAD Darwin Scheduler) least-cost pump scheduling and operation policy for each pump station has been determined while satisfying target hydraulic performance requirements such as minimum and maximum service pressures, final water level of storage tank and maximum velocity in pipeline. 32 different alternative scenarios have been created which include multi tariff energy prices, constant tariff energy price, insulated system condition, uninsulated system condition and different pump combinations. The existing base scenario and alternative scenarios which were prepared by using optimal pump schedules have been compared and the achievements of optimizing pump operation have been analyzed. At the end of the study, a satisfying result has been observed that by using determined optimal pump schedule, minimum % 14 of total energy cost can be saved in existing water supply system.
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Campisi, Salvatore. "A Water distribution system in Sicily : optimization options for the provinces of Siracusa and Ragusa /." [Beersheba, Israel] : Ben-Gurion University of the Negev, 2009. http://aranne5.lib.ad.bgu.ac.il/others/CampisiSalvatore.pdf.
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Basalike, Pie. "DESIGN, OPTIMIZATION AND ECONOMIC ANALYSIS OF PHOTOVOLTAIC WATER PUMPING TECHNOLOGIES, CASE RWANDA." Thesis, Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-28674.
Full textAbstract:
Today agriculture sector has a big contribution to the development of economy for many countries. Irrigation is a method which supplies amount of water required in proper time to the cropped land and contributes to the increases of agriculture productivity. Using diesel pump to deliver water to the place of use causes problems both in terms of profitability and environmental perspectives. Higher price of diesel increases operation costs of diesel water pumping system thereby reducing the incomes. In addition the use of diesel pump emits a huge amount of CO2 emissions which cause global warming. A possible solution to those problems is to use solar energy, a source of energy which is environmental friend and available for free. The main target of this thesis is to design and optimize a cost effective PVWPs considering three alternatives with tank storage, battery storage and a system without storages medium. The two areas in Eastern province of Rwanda were taken as case study to grow coffee and cassava with five hectares each. To run simulations, different tools have been used. Those includes CROPWAT to determine water requirements for two crops; MS Excel to design a PVWPs directly connected to irrigation system, make economic analysis, evaluate CO2 emissions and calculate other parameters. Furthermore in PVsyst software the design and simulation for PVWPs with storages medium has been carried out. Results showed that using PVWPs directly connected to irrigation system is the most profitable way when compared to the rest two alternatives. They also showed that systems designed to irrigate coffee becomes the most profitable due to huge amount of electricity surplus and higher price per kilogram of coffee. Finally fully replacement of DWPs results in annual reduction of CO2 emissions by 6.6 tonnes. Keywords: Photovoltaic system, storages medium, pumping system, economic analysis, reduction in CO2 emissions.
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Marco, Pontus. "Design & optimization of modular tanksystems for vehicle wash facilities." Thesis, Karlstads universitet, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-79009.
Full textAbstract:
Clean and safe water is important for the well being of all organisms on earth. Therefore, it is important to reduce harmful emissions from industrial processes that use water in different ways. In vehicle washing processes, water is used in high-pressure processes, as a medium for detergents, and for rinsing of vehicles. The wastewater produced by these functions passes through a water reclamation system. A water reclamation system has two main functions, to produce reusable water to be used in future washing cycles, and to separate contaminants and purify the wastewater so it can be released back into the commercial grid. The reclamation system achieves this by using a combination of different water handling processes, these include: sludge tanks, an oil-water separator, a water reclamation unit, buffer tanks, and a water purification unit. The two components that stand for the more advanced cleaning processes are the water reclamation unit and the water purification unit. In this thesis, in collaboration with the company Westmatic, the water reclamation unit consists of cyclone separators that use centrifugal forces to separate heavy particles and ozone treatment to break up organic substances and combat bad odors. The Purification unit of choice is an electrocoagulation unit that, by a direct current, creates flocculants of impurities that rises to the surface and can be mechanically removed in a water volume inside the unit. This purification process is completely chemical-free thus making the process more environmentally friendly than other purification processes used in other circumstances. This master thesis aimed to develop a dynamic design tool for a modular solution of the different parts in the water reclamation system. This design tool uses specific user input to produce construction information for each instance. As an additional sub-aim, this design tool was linked with a computer-aided design program to produce parametric 3D models with underlying blueprints. This to produce a light solution, that has a short manufacturing time and that are highly customer adjusted. The first course of action was to mathematically define the complete water reclamation system and its components. These sections were described in a flowchart that shows how the different parts interact and operate. From the wash station, wastewater runs trough a course- and fine-sludge tank. From the fine sludge tank, the wastewater is directed in two different directions. Firstly, the water is pumped to the water reclamation unit and to one or multiple buffer tanks to finally be used in the wash station as reclaimed water. Secondly, the water travels to an oil separator, pump chamber, and water purification unit. In the purification unit, 99% of the inlet mass is directed out of the system as purified water. The remaining 1% is directed to a depot that acts like the end stage of the whole system. After all equations were defined and the design was related to the user-defined input flow the design tool was structured. The program of choice to house the design tool is Microsoft Excel. In this Excel document, a user interface with navigation was constructed and the intended user is directed through a series of input pages where input data is defined. This data is used in a normally hidden page where constructional dimensions are calculated. The constructional dimensions are displayed to the user on the second last page. At this stage the Excel document can be connected to a CAD program and 3D models with blueprints can be opened that depend on the output from the Excel file. Additionally, a pipe calculator is provided on the last page of the Excel document where pipe dimensions for different cases can be found. With this solution, glass fiber tanks are molded according to the resulting blueprints that are customer specific. In this way the solution is more adaptive and easier to handle. Additionally, the provided design tool enables an easier and more well-defined methodology when deriving the different needed volume and accompanied constructional dimensions for an arbitrary water reclamation system.
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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.
Full textAbstract:
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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Mahmoud, Herman Abdulqadir Mahmoud. "Real-time operational response methodology for reducing failure impacts in water distribution systems." Thesis, University of Exeter, 2018. http://hdl.handle.net/10871/33492.
Full textAbstract:
Interruption to water services and low water pressure conditions are commonly observed problems in water distribution systems (WDSs). Of particular concern are the unplanned events, such as pipe bursts. The current regulation in the UK requires water utilities to provide reliable water service to consumers resulting in as little as possible interruptions and of as short possible duration. All this pushes water utilities toward developing and using smarter responses to these events, based on advanced tools and solutions. All with the aim to change network management style from reactive to a proactive, and reduce water losses, optimize energy use and provide better services for consumers. This thesis presents a novel methodology for efficient and effective operational, short time response to an unplanned failure event (such as pipe burst) in a WDS. The proposed automated, near real-time operational response methodology consists of isolating the failure event followed by the recovery of the affected system area by restoring the flows and pressures to normal conditions. The isolation is typically achieved by manipulating the relevant on/off valves that are located closely to the event location. The recovery involves selecting an optimal combination of suitable operational network interventions. These are selected from a number of possible options with the aim to reduce the negative impact of the failure over a pre-specified time horizon. The intervention options considered here include isolation valve manipulations, changing the pressure reducing valve’s (PRV) outlet pressure and installation and use of temporary overland bypasses from a nearby hydrant(s) in an adjacent, unaffected part of the network. The optimal mix of interventions is identified by using a multi-objective optimization approach driven by the minimization of the negative impact on the consumers and the minimization of the corresponding number of operational interventions (which acts as a surrogate for operational costs). The negative impact of a failure event was quantified here as a volume of water undelivered to consumers and was estimated by using a newly developed pressure-driven model (PDM) based hydraulic solver. The PDM based hydraulic solver was validated on a number of benchmark and real-life networks under different flow conditions. The results obtained clearly demonstrate its advantages when compared to a number of existing methods. The key advantages include the simplicity of its implementation and the ability to predict network pressures and flows in a consistently accurate, numerically stable and computationally efficient manner under both pressure-deficient and normal-flow conditions and in both steady-state and extended period simulations. The new real-time operational response methodology was applied to a real world water distribution network of D-Town. The results obtained demonstrate the effectiveness of the proposed methodology in identifying the Pareto optimal network type intervention strategies that could be ultimately presented to the control room operator for making a suitable decision in near real-time.
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Khan, Jameel Ur Rehman. "Design and optimization of a distributed generation system with the production of water and refrigeration." [Gainesville, Fla.] : University of Florida, 2006. http://purl.fcla.edu/fcla/etd/UFE0013767.
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Alvarez, Genesis Barbie. "Control Design for a Microgrid in Normal and Resiliency Modes of a Distribution System." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/94627.
Full textAbstract:
As inverter-based distributed energy resources (DERs) such as photovoltaic (PV) and battery energy storage system (BESS) penetrate within the distribution system. New challenges regarding how to utilize these devices to improve power quality arises. Before, PV systems were required to disconnect from the grid during a large disturbance, but now smart inverters are required to have dynamically controlled functions that allows them to remain connected to the grid. Monitoring power flow at the point of common coupling is one of the many functions the controller should perform. Smart inverters can inject active power to pick up critical load or inject reactive power to regulate voltage within the electric grid. In this context, this thesis focuses on a high level and local control design that incorporates DERs. Different controllers are implemented to stabilize the microgrid in an Islanding and resiliency mode. The microgrid can be used as a resiliency source when the distribution is unavailable. An average model in the D-Q frame is calculated to analyze the inherent dynamics of the current controller for the point of common coupling (PCC). The space vector approach is applied to design the voltage and frequency controller. Secondly, using inverters for Volt/VAR control (VVC) can provide a faster response for voltage regulation than traditional voltage regulation devices. Another objective of this research is to demonstrate how smart inverters and capacitor banks in the system can be used to eliminate the voltage deviation. A mixed-integer quadratic problem (MIQP) is formulated to determine the amount of reactive power that should be injected or absorbed at the appropriate nodes by inverter. The Big M method is used to address the nonconvex problem. This contribution can be used by distribution operators to minimize the voltage deviation in the system.Master of Science
Reliable power supply from the electric grid is an essential part of modern life. This critical infrastructure can be vulnerable to cascading failures or natural disasters. A solution to improve power systems resilience can be through microgrids. A microgrid is a small network of interconnected loads and distributed energy resources (DERs) such as microturbines, wind power, solar power, or traditional internal combustion engines. A microgrid can operate being connected or disconnected from the grid. This research emphases on the potentially use of a Microgrid as a resiliency source during grid restoration to pick up critical load. In this research, controllers are designed to pick up critical loads (i.e hospitals, street lights and military bases) from the distribution system in case the electric grid is unavailable. This case study includes the design of a Microgrid and it is being tested for its feasibility in an actual integration with the electric grid. Once the grid is restored the synchronization between the microgrid and electric must be conducted. Synchronization is a crucial task. An abnormal synchronization can cause a disturbance in the system, damage equipment, and overall lead to additional system outages. This thesis develops various controllers to conduct proper synchronization. Interconnecting inverter-based distributed energy resources (DERs) such as photovoltaic and battery storage within the distribution system can use the electronic devices to improve power quality. This research focuses on using these devices to improve the voltage profile within the distribution system and the frequency within the Microgrid.
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Tinh, Pham Van. "A simulation-based multi-criteria management system for optimal water supply under uncertainty." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-165776.
Full textAbstract:
For cost and reliability efficiency, optimal design and operation of pressurized water distribution networks is highly important. However, optimizing such networks is still a challenge since it requires an appropriate determination of: (1) dimension of pipe / pump / tank - decision variables (2) cost / network reliability - objective functions and (3) limits or restrictions within which the network must operate - a given set of constraints. The costs mentioned here consist in general of capital, construction, and operation costs. The reliability of a network mainly refers to the intrinsic capability of providing water with adequate volume and a certain pressure to consumers under normal and extreme conditions. These contradicting objective functions are functions of network configuration regarding component sizes and network layout. Because considerable uncertainties finally render the overall task to a highly complex problem, most recent approaches mainly focus only on finding a trade-off between minimizing cost and maximizing network reliability. To overcome these limitations, a novel model system that simultaneously considers network configuration, its operation and the relevant uncertainties is proposed in this study.
For solving this multi-objective design problem, a simulation-based optimization approach has been developed and applied. The approach couples a hydraulic model (Epanet) with the covariance matrix adaptation evolution strategy (CMA-ES) and can be operated in two different modes. These modes are (1) simulation–based Single-objective optimization and (2) simulation-based multi-objective optimization. Single-objective optimization yields the single best solution with respect to cost or network reliability, whereas multi-objective optimization produces a set of non-dominated solutions called Pareto optimal solutions which are trade-offs between cost and reliability.
In addition, to prevent a seriously under-designed network, demand uncertainties was also taken into account through a so called “robustness probability” of the network. This consideration may become useful for a more reliable water distribution network.
In order to verify the performance of the proposed approach, it was systematically tested on a number of different benchmark water distribution networks ranging from simple to complex. These benchmark networks are either gravity-fed or pumped networks which need to be optimally designed to supply urban or irrigation water demand under specific constraints. The results show that the new approach is able:
• to solve optimization problems of pressurized water distribution network design and operation regarding cost and network reliability;
• to directly determine the pumping discharge and head, thus allowing to select pumps more adequately;
• to simulate time series of tank water level;
• to eliminate redundant pipes and pumps to generate an optimal network layout;
• to respond well to complex networks other than only to simple networks;
• to perform with multiple demand loading;
• to produce reliable Pareto optimal solutions regarding multi-objective optimization.
In conclusion, the new technique can be successfully applied for optimization problems in pressurized water distribution network design and operation. The new approach has been demonstrated to be a powerful tool for optimal network design not only for irrigation but also for an urban water supply.
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Haro, Monteagudo David. "Methodology for the optimal management design of water resources system under hydrologic uncertainty." Doctoral thesis, Universitat Politècnica de València, 2015. http://hdl.handle.net/10251/45996.
Full textAbstract:
Un sistema de gestión de sequías apropiado requiere de la anticipación de los posibles
efectos que un episodio de este tipo tenga sobre el sistema de recursos hídricos. Esta tarea sin
embargo resulta más complicada de lo que parece. En primer lugar, debido al alto grado de
incertidumbre existente en la predicción de variables hidrológicas futuras. Y en segundo,
debido al riesgo de sobrerreacción en la activación de medidas de mitigación generando falsa
sensación de escasez, o sequía artificial. A este respecto, los planes especiales de sequía
proveen de herramientas para la gestión eficiente de situaciones con escasez de recursos y la
preparación de cara a futuros eventos. De todos modos, las diferentes estrategias de
operación seguidas en cada sistema de recursos hídricos hacen que las herramientas que en
algunos casos resultaron altamente útiles no lo sean tanto cuando se aplican en sistemas
distintos.
Debido a la falta de tiempo y/o al exceso de confianza en los trabajos realizados por
terceros, con excelentes resultados en sus respectivos casos, a veces se cae en el error de
implementar metodologías no del todo apropiadas en sistemas con requisitos completamente
distintos. El desarrollo y utilización de metodologías generalizadas aplicables a diferentes
sistemas y capaces de proporcionar resultados adaptados a cada caso es, por tanto, muy
deseable. Este es el caso de las herramientas de modelación de sistemas de recursos hídricos
generalizadas. Estas permiten homogeneizar los procesos mientras siguen siendo los
suficientemente adaptables para proporcionar resultados apropiados para cada caso de
estudio.
Esta tesis presenta una serie de herramientas destinadas a avanzar en el análisis y
comprensión de los sistemas de recursos hídricos, haciendo énfasis en la prevención de
sequías y la gestión de riesgos. Las herramientas desarrolladas incluyen: un modelo de
optimización generalizado para esquemas de recursos hídricos, con capacidad para la
representación detallada de cualquier sistema de recursos hídricos, y una metodología de
análisis de riesgo basada en la optimización de Monte Carlo con múltiples series sintéticas. Con
estas herramientas es posible incluir tanto la componente superficial como la subterránea del
sistema estudiado dentro del proceso de optimización. La optimización está basada en la
resolución iterativa de redes de flujo. Se probó la consistencia y eficiencia de diferentes
algoritmos de resolución para encontrar un balance entre la velocidad de cálculo, el número
de iteraciones, y la consistencia de los resultados, aportando recomendaciones para el uso de
cada algoritmo dadas las diferencias entre los mismos.
Las herramientas desarrolladas se aplican en dos casos de estudio reales en la
evaluación y posibilidad de complementación de los sistemas de monitorización y alerta
temprana de sequías existentes en los mismos. En el primer caso, se propone un enfoque
alternativo para la monitorización de la sequía en el sistema de operación anual del río Órbigo
(España), complementándolo con la utilización de la metodología de análisis de riesgo. En el
segundo caso, las herramientas se emplean en un sistema con una estrategia de operación
completamente distinta. Se estudia como el análisis de riesgo de la gestión óptima puede
ayudar a la activación anticipada de los escenarios de sequía en los sistemas de los ríos Júcar y
Turia, cuya operación es hiperanual. En esta ocasión, el sistema de indicadores existente goza
de una gran confianza por parte de los usuarios. La metodología de análisis de riesgo es, sin
embargo, capaz de anticipar los eventos de sequía con mayor alarma, aspecto que es deseable
si se quiere evitar que los episodios en desarrollo vayan a más. En ambos casos se muestra
como la evaluación anticipada de las posibles situaciones futuras del sistema permiten una
definición confiable de los escenarios de sequía con suficiente antelación para la activación
efectiva de medidas de prevención y/o mitigación en caso de ser necesarias.
La utilización de indicadores provenientes de modelos frente a indicadores basados en
datos observados es complementaria y ambos deberían utilizarse de forma conjunta para
mejorar la gestión preventiva de los sistemas de recursos hídricos. El empleo de modelos de
optimización en situaciones de incertidumbre hidrológica es muy apropiado gracias a la no
necesidad de definir reglas de gestión para obtener los mejores resultados del sistema, y
teniendo en cuenta que las reglas de operación habituales pueden no ser completamente
adecuadas en estas ocasiones.Haro Monteagudo, D. (2014). Methodology for the optimal management design of water resources system under hydrologic uncertainty [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/45996
TESIS
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Briones, Maria. "Validating the Accuracy of Neatwork, a Rural Gravity Fed Water Distribution System Design Program, Using Field Data in the Comarca Ngöbe-Bugle, Panama." Scholar Commons, 2018. https://scholarcommons.usf.edu/etd/7268.
Full textAbstract:
Despite the sustainable development goals to increase access to improved water there are still 884 million people in the world without access to an improved water source (WHO, 2017). One method to improve access to water in rural, mountainous areas, is through construction of gravity fed water distribution systems. These systems should be designed based upon fundamental principles of hydraulics. One method of doing so in a time efficient manner with minimal engineering knowledge is to utilize a downloadable computer program such as Neatwork, which aids in design of rural, gravity fed water distribution systems and has been used by volunteers in Peace Corps Panama for years. It was the goal of this research to validate the results of the Neatwork program by comparing the flow results produced in the simulation program with flow results measured at tap stands of a rural gravity fed water distribution system in the community of Alto Nube, Comarca Ngöbe Bugle, Panama.
The author measured flow under default Neatwork conditions of 40% faucets open in the system (in the field an equivalent of 8 taps) to have an initial basis as to whether the Neatwork program and field conditions yielded corresponding flows. The second objective would be to vary the number of taps open if the default condition did not produce comparable results between the field and the simulation, to pinpoint if under a certain condition of open faucets in the system the two methods would agree. The author did this by measuring flow at varying combinations from 10-100% of the open taps in the system (2-20 taps). Lastly the author observed the flow differences in the Neatwork program against the field flows, when the elevation of water in the water reservoir is set to the Neatwork default, where elevation of water is the tank outlet (at the bottom of the tank) versus when the elevation is established at the overflow at the tank (at the top of the tank) for the case of two taps open.
The author used paired t-tests to test for statistical difference between Neatwork and field produced flows. She found that for the default condition of 40% taps open and all other combinations executed between 30-80% taps open, the field and Neatwork flows did not produce statistically similar results and, in fact, had the tendency to overestimate flows. The author also found that the change in water elevation in the storage tank from outlet to overflow increased the flow at the two taps measured by 0.140 l/s and 0.145 l/s and in this case, did not change whether the flows at these taps were within desired range (0.1 -0.3 l/s). Changing the elevation of the water level in the tank in the Neatwork program to correspond to a “full” tank condition is not recommended, as assuming an empty tank will account for seasonal changes or other imperfections in topographical surveying that could reduce available head at each tap. The author also found that the orifice coefficients, θ, of 0.62 and 0.68, did not demonstrate more or less accurate results that coincided with field measurements, but rather showed the tendency of particular faucets to prefer one coefficient over the other, regardless of combination of other taps open in the system.
This study demonstrates a consistent overestimation in flow using the computer program Neatwork. Further analysis on comparisons made show that between field and flow results across each individual faucet, variations between Neatwork and the field were a result of variables dependent upon the tap, such as flow reducers or errors in surveying. Flow reducers are installed before taps to distribute flow equally amongst homes over varying distances and elevations and are fabricated using different diameter orifices depending on the location of the tap. While Neatwork allows the user to simulate the effect of these flow reducers on tap flow, it may not account for the imperfect orifices made by the simple methods used in the field to make such flow reducers.
The author recommends further investigation to be done on the results of field flow versus Neatwork simulated flow using other methods of flow reducer fabrication which produce varying degrees of accuracy in orifice sizing. The author also recommends executing these field measurements over a greater sample size of faucets and more randomized combination of open/closed taps to verify the results of this research. More work should be done to come up with a practical solution for poor and rural communities to fabricate and/or obtain more precisely sized flow reducers. A full sensitivity analysis of the input variables into the Neatwork program should be performed to understand the sensitivity of varying each input.
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Roy, Michelle. "Investigation of Future Flow Reducer Sizes in Houses Added to an Existing Gravity Flow Water System to Ensure its Sustainability." Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6580.
Full textAbstract:
Goal 6 of the United Nations Development Program’s new Sustainable Development Goals aims to ensure availability of clean water and sustainable management practices to all by the year 2030. Peace Corps Panama partners with communities in order to help provide sustainable water solutions to communities in need. Water, Sanitation, and Hygiene (WASH) Volunteers spend at least two years living in a community to identify and implement solutions to water problems and train local water committees on how to maintain their improved systems. A common solution for unequal distribution of flow in the distribution network of a gravity flow water system is through the installation of flow reducers before each faucet. These can be sized with the help of NeatWork, a free, downloadable compute software. In Panama, flow reducers (also referred to as orifices) are manufactured to create a perforated plastic diaphragm fitting placed in the distribution pipe or union section upstream of a faucet. They help ensure longevity of the aqueduct by balancing the flows between houses, thus, enabling continuous water flow for all users. An important characteristic of flow reducers is that while they can be installed in new water sys-tems, they can also be installed in existing systems to fix inequalities from inadequate original designs or extensions to the systems. However, little guidance exists for volunteers or commu-nities to ensure the sustainability of these projects. Accordingly, the object of this thesis was to investigate how adding houses to existing aqueducts would affect its serviceability and how to determine a way for communities to size the flow reducers for future houses.
The existing gravity flow water system in Santa Cruz, Panamá was surveyed including all the potential houses which were then analyzed using NeatWork. The results demonstrate that while it is better to include all potential locations during the initial survey, if it expands at an average growth rate, additional houses may decrease serviceability, but in a negligible way that will not affect the overall reliability of the distribution system.
Utilizing NeatWork, this research showed it is able to determine ideal sizes of flow reducers for additional houses that could be added. Patterns were identified and used to simplify flow reducer sizing so that community members could do it themselves. While most of the time, the ideal flow reducer size for a new house will be the same size as the flow reducer size that is installed in the closest house that is already connected to the aqueduct, sometimes this is not the case. This typically occurs towards the end of branches and in areas where not all flow reducer sizes are present. These areas are clearly identified to the water committee on a map of the distribution system that was provided to various water committee members. With this map and simple instructions, the Santa Cruz water committee can continue correctly adding flow reducers to new houses.
Through the research of this thesis, fabricating and installing flow reducers in the Santa Cruz water distribution system, and working alongside community members many lessons were learned about flow reducers and best practices. This knowledge has been converted into a guide about sustainable flow reducer projects. It has been left with current volunteers and the director of training for the WASH sector of Peace Corps Panama so that the volunteers can adapt the developed tools in their own communities.
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Brathwaite, Joy Danielle. "Value-informed space systems design and acquisition." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/43748.
Full textAbstract:
Investments in space systems are substantial, indivisible, and irreversible, characteristics that make them high-risk, especially when coupled with an uncertain demand environment. Traditional approaches to system design and acquisition, derived from a performance- or cost-centric mindset, incorporate little information about the spacecraft in relation to its environment and its value to its stakeholders. These traditional approaches, while appropriate in stable environments, are ill-suited for the current, distinctly uncertain and rapidly changing technical, and economic conditions; as such, they have to be revisited and adapted to the present context. This thesis proposes that in uncertain environments, decision-making with respect to space system design and acquisition should be value-based, or at a minimum value-informed. This research advances the value-centric paradigm by providing the theoretical basis, foundational frameworks, and supporting analytical tools for value assessment of priced and unpriced space systems.
For priced systems, stochastic models of the market environment and financial models of stakeholder preferences are developed and integrated with a spacecraft-sizing tool to assess the system's net present value. The analytical framework is applied to a case study of a communications satellite, with market, financial, and technical data obtained from the satellite operator, Intelsat. The case study investigates the implications of the value-centric versus the cost-centric design and acquisition choices. Results identify the ways in which value-optimal spacecraft design choices are contingent on both technical and market conditions, and that larger spacecraft for example, which reap economies of scale benefits, as reflected by their decreasing cost-per-transponder, are not always the best (most valuable) choices. Market conditions and technical constraints for which convergence occurs between design choices under a cost-centric and a value-centric approach are identified and discussed. In addition, an innovative approach for characterizing value uncertainty through partial moments, a technique used in finance, is adapted to an engineering context and applied to priced space systems. Partial moments disaggregate uncertainty into upside potential and downside risk, and as such, they provide the decision-maker with additional insights for value-uncertainty management in design and acquisition.
For unpriced space systems, this research first posits that their value derives from, and can be assessed through, the value of information they provide. To this effect, a Bayesian framework is created to assess system value in which the system is viewed as an information provider and the stakeholder an information recipient. Information has value to stakeholders as it changes their rational beliefs enabling them to yield higher expected pay-offs. Based on this marginal increase in expected pay-offs, a new metric, Value-of-Design (VoD), is introduced to quantify the unpriced system's value. The Bayesian framework is applied to the case of an Earth Science satellite that provides hurricane information to oil rig operators using nested Monte Carlo modeling and simulation. Probability models of stakeholders' beliefs, and economic models of pay-offs are developed and integrated with a spacecraft payload generation tool. The case study investigates the information value generated by each payload, with results pointing to clusters of payload instruments that yielded higher information value, and minimum information thresholds below which it is difficult to justify the acquisition of the system. In addition, an analytical decision tool, probabilistic Pareto fronts, is developed in the Cost-VoD trade space to provide the decision-maker with additional insights into the coupling of a system's probable value generation and its associated cost risk.
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Giraud, Xavier. "Méthodes et outils pour la conception optimale des réseaux de distribution d'électricité dans les aéronefs." Phd thesis, Institut National Polytechnique de Toulouse - INPT, 2014. http://tel.archives-ouvertes.fr/tel-00955887.
Full textAbstract:
Dans le domaine aéronautique, la dernière décennie a été marquée par une augmentation constante et progressive du taux d'électrification des systèmes embarqués. L'avion plus électrique est aujourd'hui vu comme un axe d'amélioration majeure pour l'industrie aéronautique permettant d'atteindre des objectifs toujours plus ambitieux : réduction de l'impact environnemental, rationalisation des coûts de maintenance... Dans ce contexte, le réseau de distribution électrique joue un rôle majeur. Les architectes doivent imaginer de nouveaux concepts architecturaux afin d'assurer le " service " de fourniture d'électricité tout en minimisant la masse et le coût. Ainsi les travaux de cette thèse proposent des méthodes d'aide à la conception pour les architectes de réseau. Le manuscrit se divise en 2 parties pouvant être vues comme 2 études distinctes et qui sont introduites dans le chapitre 1. La 1ère partie, traitée dans les chapitres 2 et 3, développe des méthodes et outils afin de résoudre de manière automatique et optimale 2 tâches de l'architecte : la définition des reconfigurations du réseau et l'identification de l'allocation des charges. La formalisation de ces 2 problématiques met en lumière une caractéristique commune : l'explosion combinatoire. Ainsi les résolutions sont réalisées à l'aide de méthodes issues de la recherche opérationnelle. Un processus général est défini afin de traiter les 2 tâches de manière consistante. Les aspects liés à la reconfiguration sont traités à l'aide de : la théorie des graphes pour modéliser la connectivité du réseau, un système expert capturant les règles métiers et la programmation linéaire sélectionnant les reconfigurations les plus performantes. La méthode a été appliquée avec succès sur des réseaux avions existants (A400M et A350) ainsi que sur des réseaux plus électriques prospectifs. La deuxième tâche consistant en l'allocation des charges a été résolue à l'aide de méthodes stochastiques. L'algorithme génétique utilisant une méthode de nichage se révèle être le plus performant en proposant à l'architecte réseau des solutions performantes et variées. La 2ème partie, traitée dans le chapitre 4, s'intéresse à un nouveau concept le " cœur électronique modulaire et mutualisé ". Cet organe de distribution, étroitement lié à l'avion plus électrique, se caractérise par la mutualisation de " m " modules électronique de puissance pour " c " charges électriques. Les méthodes développées dans le chapitre 4 vise à concevoir de manière optimale ce nouveau cœur en ayant 2 degrés de liberté : le nombre " m " de modules et les reconfigurations entre les " m " modules et les " c " charges. De nouveau, la formalisation du problème met en évidence l'explosion combinatoire à laquelle est confronté le concepteur. Le principal objectif de cette étude est de proposer un cadre méthodologique pour la résolution de ce problème de conception. Ainsi une heuristique a été développée pour résoudre ce problème combinatoire. Une attention particulière a été portée pour développer des modèles de composants simples et génériques dans une procédure générale organisée. Enfin une cartographie a été réalisée afin de dégager d'une part les formes de solutions les plus performantes et d'identifier les éléments ayant les impacts les plus significatifs sur la masse du système complet.
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Aubel, Laforgue Sylvie. "Un nouveau média pour l'aménagement urbain intégrant un système d'information géographique et un outil de représentation vériste et tridimensionnelle du paysage : application à l'étude du projet urbain de Saint Pierre de Chartreuse." Grenoble 1, 1997. http://www.theses.fr/1997GRE10168.
Full textAbstract:
L'instrument ideralpe est un outil pour l'etude et l'evaluation des impacts dans le paysage alpin des amenagements urbains, touristiques, d'infrastructures, etc. Produit de methodes, d'outils logiciels, materiels, et de savoir-faire empruntes a de nombreuses disciplines scientifiques, il integre trois modules techniques (sig, modele mathematique, representation 3d du paysage) qui ont a remplir une fonction precise a un stade donne du montage du projet d'amenagement. L'objet de cette these est de rendre compte des finalites de l'equipe pluridisciplinaire, des savoir-faire scientifiques et artistiques mobilises. La problematique du sig urbain pour une approche globale de l'amenagement est abordee au chapitre 1. Les projets d'amenagement etant toujours particulierement conditionne par le contexte economique, politique de la commune, nous nous attardons a l'expose des contraintes et des conditions d'evolutions de st. Pierre-de-chartreuse, site experimental (chapitre 2). La methode d'elaboration du sig urbain est l'objet du chapitre 3. Il s'agit de rechercher les donnees, leurs sources, leur format, leur disponibilite, de les collecter, d'organiser leur coherence et de les structurer pour aboutir a une base de donnees communale conforme a nos objectifs initiaux. Les traitements sur les donnees sont abordes au chapitre 4. Nous avons definis trois types de traitements : - les calculs elabores sur les donnees du sig. Ce travail est illustre par la modelisation mathematique du reseau de distribution d'eau qui, par simulations, permet de comprendre le fonctionnement et les implications de la realisation du projet d'amenagement. - la manipulation des donnees. Arc/info et cg urba sont les deux sig sur lesquels nous avons portes un regard critique. - la mise en forme des donnees 3 d du paysage pour la representation veriste et esthetique. Au dela de la conception methodologique et technique des differents modules, notre reflexion s'est focalisee sur les contraintes, les enjeux de la mise en uvre d'une approche globale de l'amenagement urbain, du travail en equipe, pour que la cooperation entre les services (technique, urbanisme) et le partage de l'information soient des realites quotidiennes. Nous evoquons quelques propositions qui nous semblent pertinentes et importantes pour ameliorer les pratiques.
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Коваленко, Владислав Вячеславович. "Дослідження режимів мереж 35/10кВ операторів системи розподілу електроенергії." Bachelor's thesis, КПІ ім. Ігоря Сікорського, 2020. https://ela.kpi.ua/handle/123456789/39563.
Full textAbstract:
В бакалаврській роботі на тему «Дослідження режимів мереж 35/10кВ операторів системи розподілу електроенергії » виділяються дві частини: перша – розрахункова (розділ1), де реалізуються загальні електроенергетичні задачі розрахунку та оптимізації режимів і визначення струмів короткого замикання для достатньо складних електричних мереж та друга – дослідницька (розділ 2), що присвячена аналізу режимів схем 35/10кВ Одесаобленерго.
Об`єктом дослідження є індивідуальна підстанція 110/35/10кВ, постачальна та розподільчі мережі 10/35кВ, та характерні проблемно-оріентовані експерементальні або промисловні моделі.
Предметом дослідження є невідомі режимні характеристики (напруги, втрати, регулюючі значення реактивної потужності, струми К.З. та інше), а також моделі матриць провідності і опору, методи рішення нелінійних електроенергетичних рівнянь та інше.
Мета роботи – підтвердити рівень інженерної кваліфікації бакалаврської роботи та згідно індивідуального завдання, виконати розробку розрахункової схеми Одесаобленерго і визначення головних характеристик (напруги, втрати потужності, споживання електроенергії) для режимних днів літнього та зимового максимуму.
Бакалаврська робота містить 67 сторінок, 29 рисунків, 7 таблиць, 4 креслення та 11 літературних посилань. Для реалізації завдання задіяно учбовий комп`ютерний комплекс L_APEZ, промислові електроенергентичні комплекси РАОТВ, Z_REGIM, OPTIM.QT. В процесі реалізації задач розроблені індивідуальні розрахункові схеми.In the bachelor's thesis on "Study of 35 / 10kV network modes of electricity distribution system operators" there are two parts: the first - calculation (section 1), which implements the general power problems of calculation and optimization of modes and short circuit currents for sufficiently complex electrical networks and the second - research (section 2), which is devoted to the analysis of the regimes of 35 / 10kV schemes of Odesaoblenergo. The object of studythere is an individual 110/35/10 kV substation, 110/35 kV supply and distribution networks, and typical problem-oriented experimental or industrial models. The subject of research there are unknown mode characteristics (voltages, losses, regulating values of reactive power, currents KZ, etc.), and also models of matrices of conductivity and resistance, methods of the decision of nonlinear electric equations and other. The goal of the work - to confirm the level of engineering qualification of the bachelor's degree and according to the individual task, to develop the calculation scheme of Odesaoblenergo and determine the main characteristics (voltage, power loss, electricity consumption) for the regime days of summer and winter maximum. The bachelor's thesis contains 67 pages, 29 drawings, 7 tables, 4 illustrations and 11 literary references. To implement the task, the educational computer complex L_APEZ, industrial power complexes RAOTV, Z_REGIM, OPTIM.QT are involved. In the process of realization of tasks individual calculation schemes are developed.
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Lin, Bi Liang, and 林碧亮. "Development of System Design Optimization for Water Distribution Networks." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/09211081973858889034.
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博士國立中央大學
土木工程研究所
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Topics related to the system design optimization for water distribution network have been discussed consistently in the literature for the past three decades. However, there are few papers on similar subject in the local publications. Given the complex nature of the water distribution system, its optimization model faces some difficulty in two major concerns- solution and practical application. This study develops a design optimization model for the water distribution network system using commercial pipe diameter as discrete variables. On solution, this model studies, improves and develops different algorithms and compares their respective applicability. On practical application, this model can be used for case study under different engineering requirements. This paper has performed a series of systematic study from theoretical propositions to practical engineering designs and obtained satisfactory results which will help the management of complex systems and offer practical applications. This study has attained the following important findings and conclusions: 1. This study used various methods to improve the solution efficiency of enumeration while retaining the characteristics of optimal solution, and its theoretical basis on optimal combination can be applied to other fields. 2. This study developed and established a rule-based heuristic approach based on the notion of evolution. Our case study results demonstrated that this approach allowed the effective finding of an economical system in a very short span, and at the same time, provided a well-working solution algorithm for large-scale system that previously had difficulty obtaining a solution. 3. When seeking solution respectively or collectively using enumeration, rule-based heuristic approach and genetic algorithm, the outcome showed that there existed a balance relationship between solution efficiency and system cost. The combination of enumeration helped improve the chance of solution, but the execution time required was relatively long. Genetic algorithm was adequate for medium-scale systems in terms of system cost and efficiency of solution finding. But for larger system, rule-based heuristic approach was more pertinent. 4. The optimization models for the design of water distribution system currently available encountered some difficulties in practical application, given the varying demands in different stages of engineering planning and the complexity of the distribution network system. The optimization model presented herein from both the theoretical and practical standpoints, with solution algorithms applied and developed, can meet the demands of practical application. In addition to enhancing the solution efficiency, the optimal design developed based on the model helped save the construction cost by 13.3% to 30.2% in comparison with conventional designs, without compromising the conformity to design criteria. 5. The design of pipe network system often put more focus on cost, while overlooking risk factors. A case in point is the design of small-region pipe network where the hydraulic power at both the main intake and auxiliary intake should be taken into account. Other risks that should be analyzed include multi-load supply pattern, the incidence of broken pipes or emergency water demand in the case fire fighting. The optimization model can give consideration to both the application and potential risks and provides a balanced point between economics and safety.
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Roshani, EHSAN. "WATER DISTRIBUTION SYSTEM DESIGN AND REHABILITATION UNDER CLIMATE CHANGE MITIGATION SCENARIOS." Thesis, 2013. http://hdl.handle.net/1974/7895.
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The water industry is a heavy consumer of electricity to pump water. Electricity generated with fossil fuel sources produce greenhouse gas (GHG) emissions that contribute to climate change. Carbon taxation and economic discounting in project planning are promising policies to reduce GHG emissions. The aim of this research is to develop novel single- and multi-objective optimization frameworks that incorporate a new gene-coding scheme and pipe ageing models (pipe roughness growth model, a pipe leakage model, and a pipe break model) to examine the impacts of a carbon tax and low discount rates on energy use, GHG emissions, and design/operation/rehabilitation decisions in water systems. Chapter 3 presents a new algorithm that optimizes the operation of pumps and reservoirs in water transmission systems. The algorithm was applied to the KamalSaleh transmission system near Arak, Iran. The results suggest that a carbon tax combined with a low discount rate produces small reductions in energy use and GHG emissions linked to pumping given the high static head of the KamalSaleh system. Chapter 4 presents a new algorithm that optimizes the design and expansion of water distribution networks. The algorithm was applied to the real-world Fairfield water network in Amherstview, Ontario, Canada. The results suggest that a carbon tax combined with a low discount rate does not significantly decrease energy use and GHG emissions because the Fairfield system had adequate installed hydraulic capacity. Chapters 5 and 6 present a new algorithm that optimizes the optimal rehabilitation type and timing of water mains in water distribution networks. In Chapter 5, the algorithm is applied to the Fairfield network to examine the impact of asset management strategies (quantity and infrastructure adjacency discounts) on system costs. The results suggest that applying discounts decreased capital and operational costs and favored pipe lining over pipe replacement and duplication. In Chapter 6, the water main rehabilitation optimization algorithm is applied to the Fairfield network to examine the impact of a carbon tax and low discount rates on energy use and GHG emissions. The results suggest that adopting a low discount rate and levying a carbon tax had a small impact in reducing energy use and GHG emissions and a significant impact in reducing leakage and pipe breaks in the Fairfield system. Further, a low discount rate and a carbon tax encouraged early investment in water main rehabilitation to reduce continuing leakage, pipe repair, energy, and GHG costs.Thesis (Ph.D, Civil Engineering) -- Queen's University, 2013-04-21 13:58:08.302
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MacLeod, Stephanie Patricia. "Evaluating the Impact of Climate Change Mitigation Strategies on Water Distribution System Design and Optimization." Thesis, 2010. http://hdl.handle.net/1974/5996.
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In response to growing environmental concerns, policy makers in Canada have been developing climate change mitigation strategies that will enable Canada to meet medium and long-term greenhouse gas (GHG) emission reduction targets. The water industry is energy- and carbon-intensive, thus the magnitude and long-term uncertainty of proposed carbon mitigation policies could have implications for water distribution system capital planning decisions that are made today.
The intent of this thesis was to examine the implications of discount rate and carbon price uncertainty on cost, energy use and GHG emissions in the design/optimization of the Amherstview water distribution system in Loyalist Township, Ontario, Canada. A non-dominated sorting genetic algorithm is coupled with the hydraulic solver EPANET2 in a single-objective optimization approach to identify network expansion designs that minimize total cost as the sum of: i) capital cost of installing new and parallel pipes and of cleaning and lining existing pipes; ii) operation cost of electricity for pumping water; and iii) carbon cost levied on electricity used for pumping water. The Amherstview system was optimized for a range of discount rates and carbon prices reflective of possible climate change mitigation strategies in Canada over the next 50 years. The problem formulation framework was developed according to a “real-world” municipal approach to water distribution system design and expansion. Decision variables such as pipe sizes are restricted to “real-world” commercially-available pipe diameters and parameter values are chosen according to engineering judgment and best-estimates. Parameter uncertainty is characterized by sensitivity analysis rather than the more computationally-demanding and data-intensive Monte Carlo simulation method. The impact of pipe material selection on energy use and GHG emissions was investigated for polyvinyl chloride and cement-mortar lined ductile iron pipes. Results from this first-ever study indicate that the discount rate and carbon prices investigated had no significant influence on energy use and GHG emissions in the Amherstview system. Pipe material selection was also found to minimally affect the amount of GHG emitted in the Amherstview system.Thesis (Master, Civil Engineering) -- Queen's University, 2010-08-26 15:01:27.174
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"Investigation of Sustainable and Reliable Design Alternatives for Water Distribution Systems." Doctoral diss., 2012. http://hdl.handle.net/2286/R.I.14590.
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abstract: Nowadays there is a pronounced interest in the need for sustainable and reliable infrastructure systems to address the challenges of the future infrastructure development. This dissertation presents the research associated with understanding various sustainable and reliable design alternatives for water distribution systems. Although design of water distribution networks (WDN) is a thoroughly studied area, most researchers seem to focus on developing algorithms to solve the non-linear hard kind of optimization problems associated with WDN design. Cost has been the objective in most of the previous studies with few models considering reliability as a constraint, and even fewer models accounting for the environmental impact of WDN. The research presented in this dissertation combines all these important objectives into a multi-objective optimization framework. The model used in this research is an integration of a genetic algorithm optimization tool with a water network solver, EPANET. The objectives considered for the optimization are Life Cycle Costs (LCC) and Life Cycle Carbon Dioxide (CO2) Emissions (LCE) whereby the system reliability is made a constraint. Three popularly used resilience metrics were investigated in this research for their efficiency in aiding the design of WDNs that are able to handle external natural and man-made shocks. The best performing resilience metric is incorporated into the optimization model as an additional objective. Various scenarios were developed for the design analysis in order to understand the trade-offs between different critical parameters considered in this research. An approach is proposed and illustrated to identify the most sustainable and resilient design alternatives from the solution set obtained by the model employed in this research. The model is demonstrated by using various benchmark networks that were studied previously. The size of the networks ranges from a simple 8-pipe system to a relatively large 2467-pipe one. The results from this research indicate that LCE can be reduced at a reasonable cost when a better design is chosen. Similarly, resilience could also be improved at an additional cost. The model used in this research is more suitable for water distribution networks. However, the methodology could be adapted to other infrastructure systems as well.Dissertation/Thesis
Ph.D. Construction 2012
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Wang, Peng. "A Systematic Investigation of Multi-Objective Evolutionary Algorithms Applied to the Water Distribution System Problem." Thesis, 2021. https://hdl.handle.net/2440/133074.
Full textAbstract:
Water distribution systems (WDSs) are one of society’s most important infrastructure assets. They consist of a great number of pumps, valves, junctions and a tremendous number of pipes that connect these nodes within the system, all of which induce a significant capital cost at the time of construction. However, there is no singular option for designing a WDS, and each potential design affects the cost and performance of the system differently (i.e., the pressure at each node and flow rates for each pipe). To identify solutions with a better trade-off between the cost and performance, multi-objective evolutionary algorithms (MOEAs) provide a robust optimisation tool to solve this type of problem. This PhD thesis focuses on improving and developing a more effective MOEA for WDS problems, and optimisation problems in general. The first stage of the research is to study the impact of select critical processes in MOEAs on algorithm performance and understand the reasons behind the performance observations. There are two chapters related to the first stage. The second stage is to develop a proposed General Multi-Objective Evolutionary Algorithm (GMOEA) and compare this with existing MOEAs for WDS problems. This is associated with the third content chapter.
In the first paper, the impact of the operators on an algorithm’s performance has been studied. The operators are the key component for exchange of information between solutions in populations to produce offspring solutions, thereby exploring alternative regions of the search space. These have a significant impact on an algorithm’s search behaviour. However, the composition and number of operators that should be included in an MOEA is generally fixed, based on choices made by the developers of these algorithms. To explore this issue, an assessment was conducted via comprehensive numerical experiments that isolate the influence of the size of the operator set, as well as its composition. In addition, the relative influence of other search processes affecting search behaviour (e.g., the selection strategy and hyperheuristic) have been studied. It has been found that operator set size is a dominant factor affecting algorithm performance, having a greater influence than operator set composition and other search processes affecting algorithm search behaviour. Moreover, it was also found that an existing MOEAs’ performance can be improved by simply increasing the number of operators used within the algorithm. This finding can be applied to justify the usage of operators for designing a new MOEA in the future.
In the second paper, a new convex hull contribution selection strategy for population-based MOEAs (termed CHCGen) has been proposed and compared with existing MOEAs in order to study the impact of the selection strategy on MOEA performance. It has been found that the CHCGen selection strategy is able to emphasise selection of the population of solutions on the convex hull of the non-dominated set of solutions. The CHCGen selection strategy has demonstrated that it can also improve an existing MOEAs’ performance. The finding suggests different selection strategies have an impact on MOEA performance. In addition, CHCGen can be used for developing a new MOEA in the future.
In the third paper, a new multi-objective evolutionary algorithm, called GMOEA(CHCGen,12,T,A)1 has been proposed by conducting comprehensive numerical experiments to determine the optimised component configuration for each MOEA process. The components considered within the algorithm construction include: the selection strategy, hyperheuristic, and operator set size. The numerical experiments not only explore the impact of each process’s component on algorithm performance comprehensively, but also investigate the correlation of each pairwise combination of the process’s components. In addition, the optimal form of the algorithm GMOEA(CHCGen,12,T,A) was compared with seven other existing MOEAs with an extended computational budget for a range of WDS problems. From the results, GMOEA(CHCGen,12,T,A) was shown not only to have outperformed all other MOEAs considered, but also to find a greater number of new Pareto front solutions for intermediate and large scale problems.Thesis (Ph.D.) -- University of Adelaide, School of Civil, Environmental and Mining Engineering, 2020
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Broad, Darren Ross. "Water distribution system optimization using metamodels." Thesis, 2014. http://hdl.handle.net/2440/98139.
Full textAbstract:
Evolutionary Algorithms (EAs) have been shown to apply well to optimizing the design and operations of water distribution systems (WDS). Recent research in the field has focussed on improving existing EAs and developing new ones so as to obtain better solutions (closer to the global optimum) and/or find solutions more efficiently. The primary aim of this research, however, has been to broaden the scope of optimization to include a number of the many factors that planning engineers need to consider when designing or planning the operations of WDS. Those factors considered here are (1) water quality criteria, (2) real-world, complex systems, and (3) the incorporation of data uncertainty. Incorporating each of these factors independently increases computational run-time of EA-based optimization of an algorithm that is already computationally intensive compared to other (inferior) algorithms that have been used in WDS optimization. Water quality models tend to run slower than hydraulic models due to the shorter timestep that is required to ensure sufficient accuracy, and the need for extended period simulations thereby increasing the simulation duration. Real-world models run slower due to their size. Data uncertainty is typically accounted for through the use of Monte Carlo simulations, that add several orders of magnitude to the computational requirements of optimization. Considering each of these factors together compounds the computational requirements to a point where it is impossible to optimize WDS using EAs in a reasonable amount of time. In this research metamodels have been used in place of simulation models within an EA to reduce this computational burden. A metamodel is a model of a model that runs much faster than the said model, but is still a high-fidelity approximation of it. The particular type of metamodel used in this research is an Artificial Neural Network (ANN) due to its theoretical capabilities and demonstrated effectiveness in water resources applications. The use of metamodels to act as surrogates for complex simulation models is not a trivial task. Therefore, guidelines have been developed on how best to incorporate them into the WDS optimization process. The overall metamodel-empowered, EA-based optimization algorithm developed in this research was applied to several case studies. Two small case studies, both variations of the New York Tunnels problem were studied for proof-of-concept purposes. They demonstrated that near globally-optimal solutions could still be found using the metamodel-based approach, i.e. there was minimal compromise in the effectiveness of the EA-based approach. Two larger, real-world problems were also studied: Wallan (operations planning) and Pacific City (system augmentation). These last two case studies were key to demonstrating the power of using metamodels in that they enabled a computational speed-up of up to 1375 times (137,500%) compared to a non-metamodel approach. This speed-up includes factoring in the computational overheads of using metamodels, i.e. time to generate calibration data and calibrate the metamodels.Thesis (Ph.D.) (Research by Publication) -- University of Adelaide, School of Civil, Environmental and Mining Engineering, 2014.
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Byambadoo, Monkhbayar. "Optimization Techniques for Water Distribution Network Design in Mongolia." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/23947067868026663165.
Full textAbstract:
碩士明志科技大學
電機工程系碩士班
105
ABSTRACT OPTIMIZATION TECHNIQUES FOR WATER DISTRIBUTION NETWORK DESIGN IN MONGOLIA Munkhbayar Byambadoo Department of Electrical Engineering Supervisor : Dr. Chia-Der Chang June 2017 Water supply system is one of the urgent issues for Mongolia. In recent years, many streams have stopped falling groundwater levels. We are doing research on save and management of water use. Ulaanbaatar has lived in half of the Mongolia's population. Therefore, the infrastructure is very important to develop and expand. Optimization of water supply system (WSS) is extremely important. In this study is first to compare the results of optimized diameter and pressure of pipes for branches of water supply system by using Genetic Algorithm (GA) and Particle Swarm Optimization (PSO). Then the results are verified by using EPANET software on the Ulaanbaatar City water supply system. GA and PSO operations are realized on MATLAB tools. Through simulation we found that the optimization techniques are well suited for optimization of water supply systems, especially large and complex systems. The study results will provide appropriate indicators for the future expansion of water supply systems in Mongolia. Keywords—Water supply system, Genetic Algorithm, Particle Swarm Optimization, EPANET software
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巫宗政, Tzong-Jeng Wu, and 巫宗政. "Indoor Distribution Antenna System Design and Optimization for HSPA Network." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/xrk7z4.
Full textAbstract:
碩士國立臺北科技大學
電腦與通訊研究所
101
With the advanced progress of High Speed Packet data Access（HSPA）network, the development of mobile communication technology has transformed from the voice service to data transmission service currently. Moreover, users of the global mobile phone take advantages of the mobile network to integrate various value-added services such as voice, multimedia streaming and community communication. According to the related study statistics, mobile users mostly access to the data network indoors, thus the indoor signal coverage rate and system capacity become key factors to determine the success of HSPA network. Since the number of users provided by HSPA network is still limited, consequently, when many users access to the network in the indoor environment, they may encounter the situation of network unavailable or jam due to the insufficient resource on the base station. Therefore, if the cell number of the indoor base station can be effectively expanded to avoid the interference effectively, the efficiency of using the mobile network resource will be improved greatly. This paper verifies expanding the small honeycomb cells respectively when implementing active and passive distributed antenna system (DAS) under the same area of indoor environment. It also measures the signal coverage scope, link quality, transmitting power and transmission rate. By the means of statistic analysis, it confirms the planning and use way suitable to the base station in the indoor hotspots. The study results show that the Active DAS with low gain antenna has a clear cell coverage scope and smaller overlapping, so the overall channel link quality Ec/Io is 3.6dB higher than that of Passive DAS, and the Pilot Pollution is decreased by 24% accordingly. With the increase of the proportion of using the high order modulation, the overall transmission performance of Active DAS is 17.7% higher than that of Passive DAS. The result of this study can provide reference for mobile communication operators in planning the HSPA network in the indoor hotzones.
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Johnston, John. "Minimizing Energy Consumption in a Water Distribution System: A Systems Modeling Approach." Thesis, 2011. http://hdl.handle.net/1969.1/ETD-TAMU-2011-05-9287.
Full textAbstract:
In a water distribution system from groundwater supply, the bulk of energy consumption is expended at pump stations. These pumps pressurize the water and transport it from the aquifer to the distribution system and to elevated storage tanks. Each pump in the system has a range of possible operating conditions with varying flow rates, hydraulic head imparted, and hydraulic efficiencies.
In this research, the water distribution system of a mid-sized city in a subtropical climate is modeled and optimized in order to minimize the energy usage of its fourteen pumps. A simplified model of the pipes, pumps, and storage tanks is designed using freely-available EPANET hydraulic modeling software. Physical and operational parameters of this model are calibrated against five weeks of observed data using a genetic algorithm to predict storage tank volume given a forecasted system demand. Uncertainty analysis on the calibrated parameters is performed to assess model sensitivity. Finally, the pumping schedule for the system's fourteen pumps is optimized using a genetic algorithm in order to minimize total energy use across a 24-hour period.
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Bexiga, Maria Inês Cardoso. "Photovoltaic powered water pumping systems: design and optimization of an irrigation system." Master's thesis, 2014. http://hdl.handle.net/10451/15897.
Full textAbstract:
Tese de mestrado integrado em Engenharia da Energia e do Ambiente, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2014Este trabalho tem como âmbito o estudo da possibilidade do uso de energia solar fotovoltaica em sistemas de bombagem de água. Foi sugerido pela Martifer Solar o dimensionamento de um sistema de irrigação para um relvado situado na sede da empresa, em Oliveira de Frades, Portugal. A área total do relvado é 16,119m2. Inicialmente foi feito o estado da arte, onde foram discutidas as várias aplicações destes sistemas e as suas vantagens. De seguida, é descrita uma metodologia de dimensionamento, servindo como um guia para dimensionar e otimizar um sistema solar de bombagem de água. Para o dimensionamento foi abordado um método apresentado em Firatoglu et al. [1]. Primeiro foi estudada a quantidade de água necessária para a irrigação. Por se tratar de um relvado, a quantidade diária de água necessária varia ao longo dos meses desde 15m3 até 80m3. Depois, foi estudado o recurso solar para o local. Foi logo concluído que a variação da quantidade de água necessária varia de forma semelhante com a radiação solar disponível. Através do estudo de parâmetros dos vários componentes, foi feita uma correspondência entre os módulos fotovoltaicos e o motor/bomba. Foram calculadas curvas de potência máxima e curvas de pontos de equilíbrio. O principal objetivo é modelar, usando o Matlab. as duas de forma a ficaram o mais próximas possível, sem o uso de qualquer controlador eletrónico. Após o estudo de várias configurações ficou concluído que o sistema seria constituído por 14 módulos fotovoltaicos(2S×7P, com um motor com os parâmetros Kv=0.18 V/rpm e Ra=0.50Ω e com tanques de armazenamento de água. A quantidade de água necessária fica assegurada ao longo de todo o ano.
This work has the objective of studying the possible application of photovoltaic solar energy to supply water pump systems. It was suggested by Martifer Solar to size an irrigation photovoltaic water pumping system. This system is studied for the location of the headquarters of the company, in Oliveira de Frades, Portugal. The total area to irrigate was 16,119 m2. A state-of-the art was made first, where advantages and different applications of these systems were presented. After, the methodology is described as a guide to sizing and optimize solar water pumping systems. For that sizing, a multi-step method was used presented in Firatoglu et al. [1]. First, water demand was studied. Because it is a grass field, values of water daily demand change from 15m3 to 80m3, depending on the month. After, average data from solar resource was studied. The first conclusion to achieve was that water demand changes seasonally in a similar way as solar radiation available. A match between PV array and motor/pump assembly was made, through the study of manufacturer’s data of the different components. Curves from maximum power point and equilibrium operation point were calculated. The main goal is to match as much as possible both curves, with no use of any electronic controller. The modulation of the system was made using Matlab. After the study of several configurations, it was concluded that the system would have 14 PV panels, (2S×7P) with a DC motor with Kv=0.18 V/rpm and Ra=0.50Ω and storage water tanks. It is assured that water demand is fulfilled throughout the year.
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Gibbs, Matthew S. "Real-coded genetic algorithm parameter setting for water distribution system optimisation." 2008. http://hdl.handle.net/2440/49644.
Full textAbstract:
The management of Water Distribution Systems (WDSs) involves making decisions about various operations in the network, including the scheduling of pump operations and setting of disinfectant dosing rates. There are often conflicting objectives in making these operational decisions, such as minimising costs while maximising the quality of the water supplied. Hence, the operation of WDSs can be very difficult, and there is generally considerable scope to improve the operational efficiency of these systems by improving the associated decision making process. In order to achieve this goal, optimisation methods known as Genetic Algorithms (GAs) have been successfully adopted to assist in determining the best possible solutions to WDS optimisation problems for a number of years. Even though there has been extensive research demonstrating the potential of GAs for improving the design and operation of WDSs, the method has not been widely adopted in practice. There are a number of reasons that may contribute to this lack of uptake, including the following difficulties: (a) developing an appropriate fitness function that is a suitable description of the objective of the optimisation including all constraints, (b) making decisions that are required to select the most appropriate variant of the algorithm, (c) determining the most appropriate parameter settings for the algorithm, and (d) a reluctance of WDS operators to accept new methods and approaches. While these are all important considerations, the correct selection of GA parameter values is addressed in this thesis. Common parameters include population size, probability of crossover, and probability of mutation. Generally, the most suitable GA parameters must be found for each individual optimisation problem, and therefore it might be expected that the best parameter values would be related to the characteristics of the associated fitness function. The result from the work undertaken in this thesis is a complete GA calibration methodology, based on the characteristics of the optimisation problem. The only input required by the user is the time available before a solution is required, which is beneficial in the WDS operation optimisation application considered, as well as many others where computationally demanding model simulations are required. Two methodologies are proposed and evaluated in this thesis, one that considers the selection pressure based on the characteristics of the fitness function, and another that is derived from the time to convergence based on genetic drift, and therefore does not require any information about the fitness function characteristics. The proposed methodologies have been compared against other GA calibration methodologies that have been proposed, as well as typical parameter values to determine the most suitable method to determine the GA parameter values. A suite of test functions has been used for the comparison, including 20 complex mathematical optimisation problems with different characteristics, as well as realistic WDS applications. Two WDS applications have been considered: one that has previously been optimised in the literature, the Cherry Hills-Brushy Plains network; and a real case study located in Sydney, Australia. The optimisation problem for the latter case study is to minimise the pumping costs involved in operating the WDS, subject to constraints on the system, including minimum disinfectant concentrations. Of the GA calibration methods compared, the proposed calibration methodology that considered selection pressure determined the best solution to the problem, producing a 30% reduction in the electricity costs for the water utility operating the WDS. The comparison of the different calibration approaches demonstrates three main results: 1. that the proposed methodology produced the best results out of the different GA calibration methods compared; 2. that the proposed methodology can be applied in practice; and 3. that a correctly calibrated GA is very beneficial when solutions are required in a limited timeframe.http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1325448
Thesis (Ph.D.) - University of Adelaide, School of Civil, Environmental and Mining Engineering, 2008
50
Gibbs, Matthew S. "Real-coded genetic algorithm parameter setting for water distribution system optimisation." Thesis, 2008. http://hdl.handle.net/2440/49644.
Full textAbstract:
The management of Water Distribution Systems (WDSs) involves making decisions about
various operations in the network, including the scheduling of pump operations and setting
of disinfectant dosing rates. There are often conflicting objectives in making these
operational decisions, such as minimising costs while maximising the quality of the water
supplied. Hence, the operation of WDSs can be very difficult, and there is generally considerable
scope to improve the operational efficiency of these systems by improving the
associated decision making process. In order to achieve this goal, optimisation methods
known as Genetic Algorithms (GAs) have been successfully adopted to assist in determining
the best possible solutions to WDS optimisation problems for a number of years.
Even though there has been extensive research demonstrating the potential of GAs for
improving the design and operation of WDSs, the method has not been widely adopted
in practice. There are a number of reasons that may contribute to this lack of uptake,
including the following difficulties: (a) developing an appropriate fitness function that is
a suitable description of the objective of the optimisation including all constraints, (b)
making decisions that are required to select the most appropriate variant of the algorithm,
(c) determining the most appropriate parameter settings for the algorithm, and (d) a reluctance
of WDS operators to accept new methods and approaches.
While these are all important considerations, the correct selection of GA parameter values
is addressed in this thesis. Common parameters include population size, probability of
crossover, and probability of mutation. Generally, the most suitable GA parameters must
be found for each individual optimisation problem, and therefore it might be expected that
the best parameter values would be related to the characteristics of the associated fitness
function.
The result from the work undertaken in this thesis is a complete GA calibration methodology,
based on the characteristics of the optimisation problem. The only input required
by the user is the time available before a solution is required, which is beneficial in the WDS operation optimisation application considered, as well as many others where computationally
demanding model simulations are required. Two methodologies are proposed
and evaluated in this thesis, one that considers the selection pressure based on the characteristics
of the fitness function, and another that is derived from the time to convergence
based on genetic drift, and therefore does not require any information about the fitness
function characteristics.
The proposed methodologies have been compared against other GA calibration methodologies
that have been proposed, as well as typical parameter values to determine the most
suitable method to determine the GA parameter values. A suite of test functions has been
used for the comparison, including 20 complex mathematical optimisation problems with
different characteristics, as well as realistic WDS applications.
Two WDS applications have been considered: one that has previously been optimised in
the literature, the Cherry Hills-Brushy Plains network; and a real case study located in
Sydney, Australia. The optimisation problem for the latter case study is to minimise the
pumping costs involved in operating the WDS, subject to constraints on the system, including
minimum disinfectant concentrations. Of the GA calibration methods compared,
the proposed calibration methodology that considered selection pressure determined the
best solution to the problem, producing a 30% reduction in the electricity costs for the
water utility operating the WDS.
The comparison of the different calibration approaches demonstrates three main results:
1. that the proposed methodology produced the best results out of the different GA
calibration methods compared;
2. that the proposed methodology can be applied in practice; and
3. that a correctly calibrated GA is very beneficial when solutions are required in a
limited timeframe.Thesis (Ph.D.) - University of Adelaide, School of Civil, Environmental and Mining Engineering, 2008