Assessing the Performance Level of a Water System

Kanakoudis, Vasilis; Tolikas, D.

doi:10.1023/b:wafo.0000044807.41719.c7

Cited by 29 publications

(19 citation statements)

References 14 publications

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“…Of course, other types of costs (like costs of water losses, loss of revenues etc. -see, e.g., [5,11,12,18]) are commonly considered in the literature. Among others, I should also mention restoration and diagnostic costs.…”

Section: Maintenance Costsmentioning

confidence: 99%

“…In literature, these costs are related to various sources and models, like a rehabilitation of a pipe and breakage repair costs (see, e.g., [12]), an extra energy, water losses and a loss of revenues (see, e.g., [11]) etc. In this paper the costs are modelled using their constant and variable part.…”

Section: In This Paper I Focus On An Evaluation Of Maintenance Costs mentioning

confidence: 99%

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Optimization of maintenance costs of a pipeline for a V-shaped hazard rate of malfunction intensities

Romaniuk¹

2018

Eksploatacja i Niezawodność – Maintenance and Reliability

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Article citation info: (*) Tekst artykułu w polskiej wersji językowej dostępny w elektronicznym wydaniu kwartalnika na stronie www.ein.org.pl IntroductionFrom the customers' point of view, the main aim of a water distribution system (which is further abbreviated as WDS) is to deliver water, moreover -water of desirable quality and in necessary quantity. Therefore, different maintenance services have to be performed, e.g., broken or simply malfunctioned pipes or other parts of a WDS should be repaired or replaced. Because water is an indispensable good for humans, therefore also scientific literature devoted to reliability of water distribution systems is abundant. Firstly, let us mention reviews of various methods, approaches and literature, which can be found in, e.g., [15,28,29]. The papers themselves are very varied -some of them concern hydraulic and physical characteristics of parts of a WDS (see, e.g., [4,17]), other discuss rather a "macro-management" of a WDS rehabilitation problem (see, e.g., [12,22]) or only a "micromanagement" scale (e.g., for a single building, see [1]). Even some monitoring systems for failures detection in a WDS are proposed (see, e.g., [23]).Usually, if maintenance costs for a WDS are considered, planning for a relatively long-time horizon should be taken into account. Such a time interval covers 20, 50 or even 60 years (see, e.g., [12]). Of course, one unit of money, which is paid now, and the same unit in 50-60 years, are not equal. Therefore, an influence of a future / present value of the money onto a calculation of the maintenance costs should be taken into account. However, most of the authors apply only a constant interest rate, as a discount factor, to calculate a present value of future cash flows. Such an assumption is, of course, too strong and unrealistic in practical situations. Therefore, in this paper I adopt a more realistic and complex model -a variable interest rate, which is described by the widely known one-factor Vasicek model. Moreover, some model for intensities of malfunctions of parts of a WDS has to be assumed. As it is proposed in literature, it can be based on selected physical aspects of a pipe and numerical equations (like the Hazen-Williams equation, see, e.g., [12]), it can be described with some type of Markov or semi-Markov process (see, e.g., [13,16,26]) or malfunctions are randomly generated using a hazard rate function (HRF). A RomAniuk m. optimization of maintenance costs of a pipeline for a V-shaped hazard rate of malfunction intensities. Eksploatacja i niezawodnosc -maintenance and Reliability 2018; 20 (1): 46-56, http://dx.doi.org/10.17531/ein.2018.1.7. maciej RomAniuk OptimizatiOn Of maintenance cOsts Of a pipeline fOr a V-shaped hazard rate Of malfunctiOn intensitiesOptymalizacja kOsztów eksplOatacyjnych rurOciągu dla V-kształtnej funkcji intensywnOści uszkOdzeń* [29]. In this paper I propose a new kind of a HRF, which can be easily adapted to real-life data and which is very efficient during the Monte Carlo simulations. Very often in...

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Section: Maintenance Costsmentioning

confidence: 99%

Section: In This Paper I Focus On An Evaluation Of Maintenance Costs mentioning

confidence: 99%

Optimization of maintenance costs of a pipeline for a V-shaped hazard rate of malfunction intensities

Romaniuk¹

2018

Eksploatacja i Niezawodność – Maintenance and Reliability

View full text Add to dashboard Cite

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“…The literature devoted to the problems of simulation of the WDS behaviour and to analysis of its reliability is very rich (see, e.g, [3,4,7,10,11,15,17,19,25,29] for a description of various approaches, and [16,28] for a more detailed review of methods and literature). Because of a necessary long-time horizon planning (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…Such an assumption may be accepted, even in practical situations (see, e.g., [28] for a more detailed discussion), but in many papers the required time is modelled using some random variable. For example,in [11], the generalized exponential density is applied. The authors also describe various types of the costs related to repairs, like the costs of a procedure itself, the costs of an extra energy (which is necessary to satisfy the public demands), the costs of water losses and a loss of revenues (which takes place, when the water demands are not satisfied).…”

mentioning

confidence: 99%

On simulation of maintenance costs for water distribution system with fuzzy parameters

Romaniuk

2016

EiN

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Article citation info: (*) Tekst artykułu w polskiej wersji językowej dostępny w elektronicznym wydaniu kwartalnika na stronie www.ein.org.pl IntroductionThe main aim of each water distribution system (WDS, water pipes network) is to deliver water of desirable quality and assumed quantity for customers. In order to meet these requirements, maintenance services, like repairs and replacements of broken or malfunctioned parts, are required.The literature devoted to the problems of simulation of the WDS behaviour and to analysis of its reliability is very rich (see, e.g, [3, 4, 7, 10, 11, 15, 17, 19, 25, 29] for a description of various approaches, and [16,28] for a more detailed review of methods and literature). Because of a necessary long-time horizon planning (e.g. 20 or even 50 years), an influence of a value of the money in the future on maintenance costs should be taken into account. Also such a problem is addressed in many papers.For example, in [20], the main aim is to estimate and validate various cost functions for different types of assets of a WDS, if their hydraulic (e.g., flow, pump head, pump power) and physical characteristics (e.g., volume, material, nominal diameter) are stored in a specially prepared data base. A method of a linear regression is used to model a dependency between various types of the costs (like an equipment cost) and the mentioned characteristics of a pipe (like a nominal diameter) based on data from several Portuguese urban water utilities. However, a method for a calculation of a present value of the total costs is not developed there in a more detailed way.Contrary to the previous paper, in [12], let's say, a "macro-management" approach for a WDS rehabilitation problem with a real long-time horizon is widely discussed. In this paper, both an economics and hydraulic capacity of a WDS is analysed, if a deterioration of a pipe follows the Hazen-Williams equation. The total costs are related RomAniuk m. on simulation of maintenance costs for water distribution system with fuzzy parameters. Eksploatacja i niezawodnoscmaintenance and Reliability 2016; 18 (4): 514-527, http://dx.doi.org/10.17531/ein.2016.4.6. to a rehabilitation of a pipe and some additional maintenance costs (mainly breakage repair costs). To model the breakage rate, the exponential dependency on an age of a pipe is assumed. The present value of the total costs is then calculated using a constant discount rate. The main aim of the whole procedure is to minimize the total costs associated with a rehabilitation, if some hydraulic constraints, necessary for a quality and a quantity of the supplied water, are preserved. As mentioned in this paper, an analysis period for such a procedure is typically equal to 30-60 years.There are also more specialized approaches to the problem of the costs estimation. For example, in [25], an optimisation procedure for a problem of minimising the costs is also described. In this case, the authors express the total cost of a renewal, risk and an unavailability of a WDS as one func...

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“…A systematic plan for replacement and remediation is in effect for the maintenance of the city waterworks [6][7][8]. Though improvement projects for old waterworks are being implemented, it is difficult to reduce the system's economic losses and improve its function via the evaluation of old pipes and accident prevention, which depend on empirical judgment [9,10].…”

Section: Introductionmentioning

confidence: 99%

Estimation of Non-Revenue Water Ratio for Sustainable Management Using Artificial Neural Network and Z-Score in Incheon, Republic of Korea

Jang

Choi

2017

Sustainability

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Abstract:The non-revenue water (NRW) ratio in a water distribution system is the ratio of the loss due to unbilled authorized consumption, apparent losses and real losses to the overall system input volume (SIV). The method of estimating the NRW ratio by measurement might not work in an area with no district metered areas (DMAs) or with unclear administrative district. Through multiple regression analyses is a statistical analysis method for calculating the NRW ratio using the main parameters of the water distribution system, although its disadvantage is lower accuracy than that of the measured NRW ratio. In this study, an artificial neural network (ANN) was used to estimate the NRW ratio. The results of the study proved that the accuracy of NRW ratio calculated by the ANN model was higher than by multiple regression analysis. The developed ANN model was shown to have an accuracy that varies depending on the number of neurons in the hidden layer. Therefore, when using the ANN model, the optimal number of neurons must be determined. In addition, the accuracy of the outlier removal condition was higher than that of the original data used condition.

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Assessing the Performance Level of a Water System

Cited by 29 publications

References 14 publications

Optimization of maintenance costs of a pipeline for a V-shaped hazard rate of malfunction intensities

Optimization of maintenance costs of a pipeline for a V-shaped hazard rate of malfunction intensities

On simulation of maintenance costs for water distribution system with fuzzy parameters

Estimation of Non-Revenue Water Ratio for Sustainable Management Using Artificial Neural Network and Z-Score in Incheon, Republic of Korea

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