scholarly journals Multi-stage parameter-constraining inverse transient analysis for pipeline condition assessment

2018 ◽  
Vol 20 (2) ◽  
pp. 281-300 ◽  
Author(s):  
Chi Zhang ◽  
Aaron C. Zecchin ◽  
Martin F. Lambert ◽  
Jinzhe Gong ◽  
Angus R. Simpson
Keyword(s):  
Transient Analysis ◽  
Distribution Systems ◽  
Water Distribution ◽  
Search Space ◽  
Condition Assessment ◽  
Estimation Accuracy ◽  
Model Parameters ◽  
Multi Stage ◽  
Study Results ◽  
Transmission Pipelines

Abstract Fault detection in water distribution systems is of critical importance for water authorities to maintain pipeline assets effectively. This paper develops an improved inverse transient analysis (ITA) method for the condition assessment of water transmission pipelines. For long transmission pipelines ITA approaches involve models using hundreds of discretized pipe reaches (therefore hundreds of model parameters). As such, these methods struggle to accurately and uniquely determine the many parameter values, despite achieving a very good fit between the model predictions and measured pressure responses. In order to improve the parameter estimation accuracy of ITA applied to these high dimensional problems, a multi-stage parameter-constraining ITA approach for pipeline condition assessment is proposed. The proposed algorithm involves the staged constraining of the parameter search-space to focus the inverse analysis on pipeline sections that have a higher likelihood of being in an anomalous state. The proposed method is verified by numerical simulations, where the results confirm that the parameters estimated by the proposed method are more accurate than the conventional ITA. The proposed method is also verified by a field case study. Results show that anomalies detected by the proposed methods are generally consistent with anomalies detected by ultrasonic measurement of pipe wall thickness.

scholarly journals A Numerical Investigation into the PAT Hydrodynamic Response to Impeller Rotational Speed Variation

2021 ◽  
Vol 13 (14) ◽  
pp. 7998
Author(s):  
Maxime Binama ◽  
Kan Kan ◽  
Hui-Xiang Chen ◽  
Yuan Zheng ◽  
Daqing Zhou ◽  
...  
Keyword(s):  
Rotational Speed ◽  
Distribution Systems ◽  
Water Distribution ◽  
Production Efficiency ◽  
Operating Conditions ◽  
Energy Regulation ◽  
Speed Increase ◽  
Energy Field ◽  
Long Run ◽  
Study Results

The utilization of pump as turbines (PATs) within water distribution systems for energy regulation and hydroelectricity generation purposes has increasingly attracted the energy field players’ attention. However, its power production efficiency still faces difficulties due to PAT’s lack of flow control ability in such dynamic systems. This has eventually led to the introduction of the so-called “variable operating strategy” or VOS, where the impeller rotational speed may be controlled to satisfy the system-required flow conditions. Taking from these grounds, this study numerically investigates PAT eventual flow structures formation mechanism, especially when subjected to varying impeller rotational speed. CFD-backed numerical simulations were conducted on PAT flow under four operating conditions (1.00 QBEP, 0.82 QBEP, 0.74 QBEP, and 0.55 QBEP), considering five impeller rotational speeds (110 rpm, 130 rpm, 150 rpm, 170 rpm, and 190 rpm). Study results have shown that both PAT’s flow and pressure fields deteriorate with the machine influx decrease, where the impeller rotational speed increase is found to alleviate PAT pressure pulsation levels under high-flow operating conditions, while it worsens them under part-load conditions. This study’s results add value to a thorough understanding of PAT flow dynamics, which, in a long run, contributes to the solution of the so-far existent technical issues.

scholarly journals Modeling Bacterial Regrowth and Trihalomethane Formation in Water Distribution Systems

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 463
Author(s):  
Gopinathan R. Abhijith ◽  
Leonid Kadinski ◽  
Avi Ostfeld
Keyword(s):  
Distribution Systems ◽  
Water Distribution ◽  
Mechanistic Model ◽  
Water Distribution Systems ◽  
Sensitivity Study ◽  
Operating Conditions ◽  
Growth Rate Constant ◽  
Model Parameters ◽  
Bacterial Regrowth ◽  
The Impact

The formation of bacterial regrowth and disinfection by-products is ubiquitous in chlorinated water distribution systems (WDSs) operated with organic loads. A generic, easy-to-use mechanistic model describing the fundamental processes governing the interrelationship between chlorine, total organic carbon (TOC), and bacteria to analyze the spatiotemporal water quality variations in WDSs was developed using EPANET-MSX. The representation of multispecies reactions was simplified to minimize the interdependent model parameters. The physicochemical/biological processes that cannot be experimentally determined were neglected. The effects of source water characteristics and water residence time on controlling bacterial regrowth and Trihalomethane (THM) formation in two well-tested systems under chlorinated and non-chlorinated conditions were analyzed by applying the model. The results established that a 100% increase in the free chlorine concentration and a 50% reduction in the TOC at the source effectuated a 5.87 log scale decrement in the bacteriological activity at the expense of a 60% increase in THM formation. The sensitivity study showed the impact of the operating conditions and the network characteristics in determining parameter sensitivities to model outputs. The maximum specific growth rate constant for bulk phase bacteria was found to be the most sensitive parameter to the predicted bacterial regrowth.

scholarly journals Development and identification of a multi-species water quality model for reclaimed water distribution systems

2015 ◽  
Vol 5 (3) ◽  
pp. 360-371
Author(s):  
Shun Li ◽  
Fu Sun ◽  
Siyu Zeng ◽  
Xin Dong ◽  
Pengfei Du
Keyword(s):  
Water Quality ◽  
Distribution Systems ◽  
Water Distribution ◽  
Reclaimed Water ◽  
Water Distribution Systems ◽  
Water Quality Model ◽  
Bulk Liquid ◽  
Model Parameters ◽  
Quality Model ◽  
Long Distance

With the rapid development of a centralized wastewater reuse scheme in China, water quality concerns arise considering the long-distance transport of reclaimed water in distribution systems from wastewater treatment plants to points of use. To this end, a multi-species water quality model for reclaimed water distribution systems (RWDSs) was developed and validated against the data from part of a full-scale RWDS in Beijing. The model could simulate organics, ammonia nitrogen, residual chlorine, inert particles, and six microbial species, i.e. fecal coliforms, Enterococcus spp., Salmonella spp., Mycobacterium spp., and other heterotrophic and autotrophic bacteria, in both the bulk liquid and the biofilm. Altogether, 56 reaction processes were involved, and 37 model parameters and seven initial values were identified. Despite the limited monitoring data and the associated gross uncertainty, the model could simulate the reclaimed water quality in the RWDS with acceptable accuracy. Regional sensitivity analysis suggested that the model had a balanced structure with a large proportion of sensitive parameters, and the sensitivity of model parameters could be reasonably interpreted by current knowledge or observation. Furthermore, the most sensitive model parameters could generally be well identified with uncertainties significantly reduced, which also favored the trustworthiness of the model. Finally, future plans to improve and apply the model were also discussed.

Multi-stage response to contaminant ingress into water distribution systems and probability quantification

2009 ◽  
Vol 36 (11) ◽  
pp. 1764-1772 ◽  
Author(s):  
Hailiang Shen ◽  
Edward A. McBean ◽  
Mirnader Ghazali
Keyword(s):  
Data Mining ◽  
Distribution System ◽  
Euclidean Distance ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution System ◽  
Location Information ◽  
Multi Stage ◽  
Actual Point

A multi-stage response procedure for identifying possible ingress nodes (PINs) and quantifying the likelihood that a PIN in a given water distribution system is the actual point of ingress is described. The procedure uses data mining to successively decrease the number of PINs based on a pre-constructed database. In each stage, query sentences are executed to locate the PINs and a Euclidean distance is proposed to estimate the probability, to allow the identification of locations with the highest probabilities of being the true ingress location. As demonstrated in a case study, the ranges of PINs are reduced in the 1st, 2nd, and 3rd stages; except the first sensor alarm, the Euclidean distance metric can identify the true ingress node with the program run-time of less than 2 min; the multi-stage procedure saves roughly 3 h in identifying the true ingress node after the second sensor alarm, instead of waiting for a third sensor alarm to provide the location information. The multi-stage response procedure is shown to be an effective and efficient way for identification and probability quantification of PINs.

scholarly journals A hybrid cuckoo–harmony search algorithm for optimal design of water distribution systems

2015 ◽  
Vol 18 (3) ◽  
pp. 544-563 ◽  
Author(s):  
Razi Sheikholeslami ◽  
Aaron C. Zecchin ◽  
Feifei Zheng ◽  
Siamak Talatahari
Keyword(s):  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Heuristic Algorithms ◽  
Optimization Problems ◽  
Search Algorithm ◽  
Harmony Search ◽  
Cuckoo Search ◽  
Search Space ◽  
Optimization Method

Meta-heuristic algorithms have been broadly used to deal with a range of water resources optimization problems over the past decades. One issue that exists in the use of these algorithms is the requirement of large computational resources, especially when handling real-world problems. To overcome this challenge, this paper develops a hybrid optimization method, the so-called CSHS, in which a cuckoo search (CS) algorithm is combined with a harmony search (HS) scheme. Within this hybrid framework, the CS is employed to find the promising regions of the search space within the initial explorative stages of the search, followed by a thorough exploitation phase using the combined CS and HS algorithms. The utility of the proposed CSHS is demonstrated using four water distribution system design problems with increased scales and complexity. The obtained results reveal that the CSHS method outperforms the standard CS, as well as the majority of other meta-heuristics that have previously been applied to the case studies investigated, in terms of efficiently seeking optimal solutions. Furthermore, the CSHS has two control parameters that need to be fine-tuned compared to many other algorithms, which is appealing for its practical application as an extensive parameter-calibration process is typically computationally very demanding.

Adaptable urban water demand prediction system

2015 ◽  
Vol 15 (5) ◽  
pp. 958-964 ◽  
Author(s):  
G. Banjac ◽  
M. Vašak ◽  
M. Baotić
Keyword(s):  
Mutual Information ◽  
Water Demand ◽  
Distribution Systems ◽  
Water Distribution ◽  
Meteorological Data ◽  
Model Parameters ◽  
Prediction System ◽  
Prediction Ability ◽  
Demand Prediction ◽  
Water Demand Prediction

In this work, identification of 24-hours-ahead water demand prediction model based on historical water demand data is considered. As part of the identification procedure, the input variable selection algorithm based on partial mutual information is implemented. It is shown that meteorological data on a daily basis are not relevant for the water demand prediction in the sense of partial mutual information for the analysed water distribution systems of the cities of Tavira, Algarve, Portugal and Evanton East, Scotland, UK. Water demand prediction system is modelled using artificial neural networks, which offer a great potential for the identification of complex dynamic systems. The adaptive tuning procedure of model parameters is also developed in order to enable the model to adapt to changes in the system. A significant improvement of the prediction ability of such a model in relation to the model with fixed parameters is shown when a certain trend is present in the water demand profile.

Operational Costs Optimization in Water Distribution Systems

2014 ◽  
Author(s):  
Dhafar Al-Ani ◽  
HamedHossien Afshari ◽  
Saeid Habibi
Keyword(s):  
Distribution Systems ◽  
Water Distribution ◽  
Optimization Problems ◽  
Water Distribution Systems ◽  
Cost Savings ◽  
Search Space ◽  
Optimal Solutions ◽  
Multi Objective Optimization ◽  
Multi Objective ◽  
Objective Space

Pump management and reservoir management have many similarities, and therefore, should ideally be analyzed in an integrated way to plan effectively the daily operation of water distribution systems. Historically, these two management activities have been evolved as separate tasks in energy-efficiency (i.e., energy optimization) studies and are often carried out in an isolated way. The latter being most often associated directly with the concepts of multimodal and multi-objective optimization problems, whereas the former is usually considered as a single optimization problem to be solved. When some single optimization problems appear at part of the solution tied to a local (i.e., regional) search-space (i.e., objective space), this artificial integration (i.e., multi-modal and multi-objective optimization) can always obtain optimal solutions. Similarly when system constraints and load conditions are considered, a set of feasible and innovative optimal solutions can be obtained in order to continue the enhancement of energy consumption that turns into a significant reduction in the overall operational cost (i.e., a potential of 6.24% cost savings) without affecting the level of services provided to the clients in a safe and protected manner.

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