Towards Achieving a Reliable Leakage Detection and Localization Algorithm for Application in Water Piping Networks: An Overview
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paper_title: Study on New Methods of Improving the Accuracy of Leak Detection and Location of Natural Gas Pipeline

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As negative pressure wave is applied to leak detection and location of natural gas pipeline, the key is how to realize accurate measurement of propagation velocity of pressure wave and time difference. However, there exists problem of lower accuracy in negative pressure wave method. Aiming at the problems of velocity measurement formula with low precision and low accuracy of leaking location, a modified velocity measurement formula is proposed. In addition, based on the theory of singularity detection of wavelet transform, the singular characteristic of the transform wave caused by pipeline leakage is detected accurately. The experimental results show that it can achieve leak detection and location of natural gas with higher accuracy through these methods.
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paper_title: Leakage detection algorithm integrating water distribution networks hydraulic model

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Paper presented at SimHydro 2017: Choosing the right model in applied hydraulics, 14-16 June 2017, Sophia Antipolis, France
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paper_title: Pressure Management Strategies for Water Loss Reduction in Large-Scale Water Piping Networks: A Review

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In water distribution networks (WDNs), water loss through leaking pipes is inevitable, as it constitutes a major threat to the operational services of water utilities. While water utilities are keen to providing an adequate supply of water to its end users, the undermined service quality, wasted energy resources and financial loss caused by leakages are major concerns. The financial loss, among others, associated with leaky pipes is increasingly growing at an alarming rate in recent years. Therefore, monitoring pipelines health through leakage control is crucial. Nevertheless, several methods for controlling leakages in WDNs have proposed. Research efforts conducted in the past acknowledged water pressure control as an effective method for reducing losses in water piping networks. Although, adequate pressure is required in the system to meet customer’s demands, it is a general agreement that reducing pressure will reduce the leakage flow rate as well as the possibility of pipe burst or crack. Several pressure management strategies have been proposed for leakage reduction in water distribution systems. In this work, we present an overview of the pressure management approaches proposed for reducing leakages in water distribution networks. Some previous and recent research efforts are outlined. Furthermore, information about leakage control, which may be useful for water utilities and pipeline engineers are provided.
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paper_title: A review of methods for leakage management in pipe networks

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Leakage in water distribution systems is an important issue which is affecting water companies and their customers worldwide. It is therefore no surprise that it has attracted a lot of attention by both practitioners and researchers over the past years. Most of the leakage management related methods developed so far can be broadly classified as follows: (1) leakage assessment methods which are focusing on quantifying the amount of water lost; (2) leakage detection methods which are primarily concerned with the detection of leakage hotspots and (3) leakage control models which are focused on the effective control of current and future leakage levels. This paper provides a comprehensive review of the above methods with the objective to identify the current state-of-the-art in the field and to then make recommendations for future work. The review ends with the main conclusion that despite all the advancements made in the past, there is still a lot of scope and need for further work, especially in area of rea...
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paper_title: Water losses investigation and evaluation in water distribution system – the case of SA city in China

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Faced with the severe leakage and chaotic water management situation in developing countries, this research is committed to provide an appropriate and practical water audit calculation method for most water companies so as to guide their leakage control management. It prepares a recommended basic standard terminology for calculation of real and apparent losses, which can be consistent with practice in China. Due to more detailed subdivision of unmetered water along with water component analysis, the water consumption of SA city can be calculated more accurately. The proportion of water loss in SA is 18.02%, while unbilled authorized consumption contributes no more than 1% to the total water consumption. Meanwhile, the “Neighbourhood Metering Area (NMA)” project in SA city also suggests that metering inaccuracies and leakage on service connections up to the point of customer metering can be prioritized for active leakage control in China.
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paper_title: Wavelet transform analysis of acoustic emission in monitoring friction stir welding of 6061 aluminum

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In this paper, acoustic emission (AE) signals are detected and preliminarily analyzed in order to investigate the possibility of applying the AE technique for the in-process monitoring of an entire friction-stir-welding (FSW) process. Experimental tests are carried out using a high-speed rotating tool traversing on two, butted 6061 aluminum alloy plates with three equally spaced gaps made of two notches aligned along the butting joint of the parts. The wavelet transform (WT) is used to decompose the AE signal into various discrete series of sequences over different frequency bands. There are significant sudden changes in the band energy at the moment when the probe penetrates into and pulls out of the weld joint, as well as when the shoulder makes contact with or detaches from the plates. The band energy variation during the traversing of the tool over the defected region reflects the existence, location, and size of the weld defects. A three-dimensional representation of band energy vs time and scale gives valuable information on the potential weld defects during friction stir welding. Coupled with a contour mapping, the representation can be effectively utilized for monitoring the transient welding state and quickly identifying gap defects.
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paper_title: Monitoring of Distributed Pipeline Systems by Wireless Sensor Networks

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This paper describes a sensor network platform for pipeline system monitoring. Pipeline systems are widely used for distribution and transportation of petroleum, natural gas, water, and sewage. Leaks and ruptures due to an aging and fast decaying pipeline system infrastructure cost millions of dollars a year; they also make clear the necessity for continuous, automatic monitoring systems that can provide early detection and early warning of defects, such as corrosion and leaks, before they reach the magnitude of a major disaster. In this paper, we discuss how sensor networks can detect, localize, and quantify bursts, leaks and other anomalies in pipeline systems. Lamb waves are guided ultrasonic waves that can propagate for considerable distances in plates. Research has shown that it is possible to detect flaws over a large area with active sensing devices such as Lead Zirconate Titanate (PZT) for simultaneous actuation and sensing. PZT sensors can be mounted on the curve surface of the pipelines for generating and measuring guided waves that propagate along the pipes. A network of PZT actuators/sensors provide a real-time continuous and automatic monitoring of the health of the pipeline systems. Complications that encountered in Lamb wave propagation include the existence of multiple propagation modes and the dispersive nature of the modes, which makes the sensing, communication, and control a difficult task. In this paper, we will address the detection and localization problems for the proposed acoustic sensor networks using signal processing techniques. We will discuss strategies to deal with the Lamb wave dispersive propagation to achieve reasonable performance for real-time monitoring.
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paper_title: LEAK DETECTION IN WATER-FILLED PLASTIC PIPES THROUGH THE APPLICATION OF TUNED WAVELET TRANSFORMS TO ACOUSTIC EMISSION SIGNALS

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A new method to detect leakage in a water-filled plastic pipe is proposed. In this method, a leakage signal-signature in time domain is first captured by monitoring the Short Time Fourier Transforms (STFT) of AE (Acoustic Emission) signals over a relatively long time-interval. The captured signal is then used to find a mother wavelet (tuned wavelet) for the best signal localization in time and frequency domains. The technique for AE signal detection using tuned wavelet is then described. Practical application of the method proposed herein is then presented using a water-filled plastic pipe as a case study. Signals generated from this experimental setup are collected to identify leakage signal-signatures from other interfering signals (background, pipe natural frequency, splash and environmental noise). The results of the experiment prove that using tuned wavelet, AE events can be detected and identified precisely in time. In addition, sources of signals due to leakage and their respective energy levels can also be recognized.
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paper_title: Hierarchical Leak Detection and Localization Method in Natural Gas Pipeline Monitoring Sensor Networks

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In light of the problems of low recognition efficiency, high false rates and poor localization accuracy in traditional pipeline security detection technology, this paper proposes a type of hierarchical leak detection and localization method for use in natural gas pipeline monitoring sensor networks. In the signal preprocessing phase, original monitoring signals are dealt with by wavelet transform technology to extract the single mode signals as well as characteristic parameters. In the initial recognition phase, a multi-classifier model based on SVM is constructed and characteristic parameters are sent as input vectors to the multi-classifier for initial recognition. In the final decision phase, an improved evidence combination rule is designed to integrate initial recognition results for final decisions. Furthermore, a weighted average localization algorithm based on time difference of arrival is introduced for determining the leak point’s position. Experimental results illustrate that this hierarchical pipeline leak detection and localization method could effectively improve the accuracy of the leak point localization and reduce the undetected rate as well as false alarm rate.
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paper_title: Leak noise propagation and attenuation in submerged plastic water pipes

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Detection of water leaks in buried distribution pipes using acoustic methods is common practice in many countries. Correlation techniques are widely used in leak detection, and these have been extremely effective when attempting to locate leaks in metal pipes. However, a number of difficulties have been highlighted when trying to determine the position of leaks in plastic pipes. Of particular interest here is what happens to the leak noise when the pipe passes through an expanse of water, such as across a river or lake. In this paper, the low-frequency acoustic propagation and attenuation characteristics of a submerged plastic water pipe are investigated experimentally in the laboratory, supported by predictions from a theoretical model. It is found that, whilst the signal attenuation for a submerged pipe is increased relative to that for a similar in-vacuo pipe, energy does not, in fact, radiate into the water; furthermore, the attenuation is small compared with that for a pipe buried in soil.
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paper_title: A model of the correlation function of leak noise in buried plastic pipes

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A common technique for locating leaks in buried water distribution pipes is the use of the cross-correlation on two measured acoustic signals, on either side of a leak. This technique can be problematic for locating leaks in plastic pipes as the acoustic signals in these pipes are generally narrow-band and low frequency. The effectiveness of the cross-correlation technique for detecting leaks in plastic pipes has been investigated experimentally in an earlier study. This paper develops an analytical model to predict the cross-correlation function of leak signals in plastic pipes. The model is based on a theoretical formulation of wave propagation in a fluid-filled pipe in vacuo and the assumption that the leak sound, at source, has a flat spectrum over the bandwidth of interest. The analytical model is used to explain some of the features of correlation measurements made in actual water pipes. Leak noise signals are generally passed through a band-pass filter before calculating the cross-correlation function. The model is used to demonstrate the importance of the cut-off frequency of the high-pass filter and the insensitivity of the correlation to the cut-off frequency of the low-pass filter.
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paper_title: Wavelet-based AE characterization of composite materials

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Abstract This paper addresses an application of recently developed wavelet-based signal processing technique on a composite fracture behavior study. Here, the wavelet methodology is introduced, and a complete procedure of wavelet-based acoustic emission (AE) analysis methods developed by the author are demonstrated. In this research, the AE signals from glass fiber reinforced (GFR) composites are collected during the standard quasi-static tensile testing and transformed by the Daubechies discrete wavelets using the programs developed by the author. Based on AE tests, the fracture behaviors are studied for the material. In the study of GFR composite fracture behavior, classical linear fracture mechanics method is used for comparison. The exponential constant m value used to determine the relationship between stress and stress intensity factor are compared relative to the classical fracture mechanics and the AE techniques. In order to demonstrate the advantage of the wavelet-based AE techniques, the conventional AE analysis is also provided side-by-side for comparison. The results verify that the wavelet-based method better approximates residual strength relative to the classical AE techniques. In this paper, the results of the wavelet-based AE analysis of glass fiber composites are presented. The results indicate that wavelets-based signal processing is an efficient tool in the analysis and the transformation of AE signals.
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paper_title: An overview of pipeline leak detection and location systems

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Leak detection in transmission pipelines is crucially important for safe operation. Delay in detecting leaks leads to loss of property and human life in fire hazards and loss of valuable material. Leaking of methane and hydrocarbon gas causes negative impacts on the eco system such as global warming and air pollution. Pipeline leak detection systems play a key role in minimization of the probability of occurrence of leaks and hence their impacts. Today there are many available technologies in the domain of leak detection. This paper provides an overview on external and internal leak detection and location systems and a summary of comparison regarding performance of each system.
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paper_title: Distributed Optical Fibre Sensors and their Applications in Pipeline Monitoring

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Health monitoring of civil infrastructure systems has recently emerged as a powerful tool for condition assessment of infrastructure performance. With the widespread use of modern telecommunication technologies, structures could be monitored periodically from a central station located several kilometres away from the field. This remote capability allows immediate damage detection, so that necessary actions are taken to reduce the risk. Optical fiber sensors offer a relatively new technology for monitoring the performance of spatially distributed structures such as pipelines. In this regards, several commercially available strain and temperature sensing equipment such as discrete FBGs (Fibre Bragg Gratings) and fully distributed sensing techniques such as Raman DTS (distributed temperature sensor) and Brillouin Optical Time Domain Reflectometry (BOTDR) typically offer sensing lengths of the order of 100 km's. Distributed fiber optic sensing offers the ability to measure temperatures and/or strains at thousands of points along a single fiber. In this paper, the authors will give a brief overview of these optical fiber technologies, outline potential applications of these technologies for geotechnical engineering applications and experience in utilising BOTDR in water pipeline monitoring application.
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paper_title: Intelligent pipelines using fiber optic sensors

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This paper presents an investigation of the application of "long gage" fiber optic sensors (FOS) to monitor the behaviour and integrity of pipelines. A description of the long gage sensor technology is provided, together with the sensor system developed for structural applications. Tests were conducted on pipe sections under a variety of load conditions, including internal pressure, axial compression, bending and local buckling. Long gage sensors were boneded to the pipes and displacements measured using a FOX-TEK FTI 3300 instrument that employs an interferometric technique to obtain displacements to an acuracy of 20 microns. Results obtained showed that the FOS could track changes in loads, detect prebuckling deformations, and measure post-buckling plastic strains. The long gage sensors were then applied to a tailings pipeline in northern Alberta (Canada) to monitor continuously the pipe wall thinning due to erosion/corosion. Employing the FTI 3300 with a PC containing an Aircard for wireless transmission, test data were monitored remotely through internet access. Using analytical models in combination with real-time measurements of the pipe's response, predictions of the operational lifetime for the pipe were made.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
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paper_title: A Source Separation Technique for Processing of Thermometric Data From Fiber-Optic DTS Measurements for Water Leakage Identification in Dikes

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Distributed temperature sensors (DTSs) show real advantages over conventional temperature sensing technology such as low cost for long-range measurement, durability, stability, insensitivity to external perturbations, etc. They are particularly interesting for long-term health assessment of civil engineering structures such as dikes. In this paper, we address the problem of identification of leakage in dikes based on real thermometric data recorded by DTS. Formulating this task as a source separation problem, we propose a methodology based on Principal Component Analysis (PCA) and Independent Component Analysis (ICA). As the first PCA estimated source extracts an energetic subspace, other PCA sources allow to access the leakages. The energy of a leakage being very low compared to the entire data, a temporal windowing approach guarantees the presence of the leakages on these other PCA sources. However, on these sources, the leakages are not well separated from other factors like drains. An ICA processing, providing independent sources, is thus proposed to achieve better identification of the leakages. The study of different preprocessing steps such as normalization, spatial gradient, and transposition allows to propose a final scheme that represents a first step towards the automation of the leakage identification problem.
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paper_title: An overview of pipeline leak detection and location systems

paper_content:

Leak detection in transmission pipelines is crucially important for safe operation. Delay in detecting leaks leads to loss of property and human life in fire hazards and loss of valuable material. Leaking of methane and hydrocarbon gas causes negative impacts on the eco system such as global warming and air pollution. Pipeline leak detection systems play a key role in minimization of the probability of occurrence of leaks and hence their impacts. Today there are many available technologies in the domain of leak detection. This paper provides an overview on external and internal leak detection and location systems and a summary of comparison regarding performance of each system.
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paper_title: Hierarchical Leak Detection and Localization Method in Natural Gas Pipeline Monitoring Sensor Networks

paper_content:

In light of the problems of low recognition efficiency, high false rates and poor localization accuracy in traditional pipeline security detection technology, this paper proposes a type of hierarchical leak detection and localization method for use in natural gas pipeline monitoring sensor networks. In the signal preprocessing phase, original monitoring signals are dealt with by wavelet transform technology to extract the single mode signals as well as characteristic parameters. In the initial recognition phase, a multi-classifier model based on SVM is constructed and characteristic parameters are sent as input vectors to the multi-classifier for initial recognition. In the final decision phase, an improved evidence combination rule is designed to integrate initial recognition results for final decisions. Furthermore, a weighted average localization algorithm based on time difference of arrival is introduced for determining the leak point’s position. Experimental results illustrate that this hierarchical pipeline leak detection and localization method could effectively improve the accuracy of the leak point localization and reduce the undetected rate as well as false alarm rate.
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paper_title: MISE-PIPE : Magnetic induction-based wireless sensor networks for underground pipeline monitoring

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Underground pipelines constitute one of the most important ways to transport large amounts of fluid (e.g. oil and water) through long distances. However, existing leakage detection techniques do not work well in monitoring the underground pipelines due to the harsh underground environmental conditions. In this paper, a new solution, the magnetic induction (MI)-based wireless sensor network for underground pipeline monitoring (MISE-PIPE), is introduced to provide low-cost and real-time leakage detection and localization for underground pipelines. MISE-PIPE detects and localizes leakage by jointly utilizing the measurements of different types of sensors that are located both inside and around the underground pipelines. By adopting an MI waveguide technique, the measurements of different types of the sensors throughout the pipeline network can be reported to the administration center in real-time. The system architecture and operational framework of MISE-PIPE is first developed. Based on the operational framework, research challenges and open research issues are then discussed.
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paper_title: Pressure wave behaviour and leak detection in pipelines

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In the present work on-line computational techniques have been developed and used in the analysis of hydraulic transients caused by leakage, in order to detect and locate pipeline ruptures. Pressure transients were obtained in two PVC pipelines 34″ diameter by using four pressure transducers connected to a PC computer equipped with A/D and D/A converters. The pipelines were 433 m and 1,248 m long. Leaks were simulated at different positions along the pipelines. Experiments were carried out for different liquid flow rates corresponding to Reynolds number in the range from 2,000 to 13,000. Leak percentage were in the range from 5% to 50% of the nominal liquid flow. A computer program to be run on-line was developed to simulate the leak, to read and filter the pressure transducers data, to display the pressure transient plots and to obtain leak location information. The detection system showed good performance in the detection of small leaks. Leaks as small as 5 % of the nominal liquid flow rate are readily detected. Leak locations were computed from pulse time delay between the various pressure transducers. The computed leak positions approached the actual values with precision. The developed software shows to be a very useful tool to the automatic supervision of pipelines as instantaneous leaks are readily detected and located.
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paper_title: Negative pressure wave based pipeline Leak Detection: Challenges and algorithms

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Negative pressure wave is a popular method to detect the occurrence and location of leak incidents in oil/gas pipeline. Three core technical challenges and related algorithm are discussed in this paper. The first is data quality. The balance between noise level and locating precision is discussed in filter design. The second one is dynamic slope in anomaly detection, whence a bi-SPC (Static Process Control) algorithms is proposed to make the threshold be adaptive. The third one is the false alarm caused normal working condition changes. Multiple-sensor paring algorithms is presented. With these algorithms, the robustness and locating precision of LDS (Leak Detection System) can be ensured.
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paper_title: Hydraulic Transients used for Leakage Detection in Water Distribution Systems

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The current paper focuses on leakage detection and location in pipe networks based on a recent and novel approach, known as inverse transient analysis. The main idea behind this methodology is the identification of leaks location in pipe networks using observed pressure data, collected during the occurrence of transient events, and the minimisation of the difference between observed and calculated parameters. This approach is presented conceptually and implemented in a software tool. The methodology is tested and verified with laboratory data collected in an experimental facility at Instituto Superior Tecnico (Technical University of Lisbon). Based on this preliminary data analysis, the main practical difficulties of the implementation of this methodology in field network systems are outlined.
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paper_title: Leak Detection in Pipelines using the Damping of Fluid Transients

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Leaks in pipelines contribute to damping of transient events. That fact leads to a method of finding location and magnitude of leaks. Because the problem of transient flow in pipes is nearly linear, the solution of the governing equations can be expressed in terms of a Fourier series. All Fourier components are damped uniformly by steady pipe friction, but each component is damped differently in the presence of a leak. Thus, overall leak-induced damping can be divided into two parts. The magnitude of the damping indicates the size of a leak, whereas different damping ratios of the various Fourier components are used to find the location of a leak. This method does not require rigorous determination and modeling of boundary conditions and transient behavior in the pipeline. The technique is successful in detecting, locating, and quantifying a 0.1% size leak with respect to the cross-sectional area of a pipeline.
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paper_title: Experimental Observation and Analysis of Inverse Transients for Pipeline Leak Detection

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Fluid transients result in a substantial amount of data as pressure waves propagate throughout pipes. A new generation of leak detection and pipe roughness calibration techniques has arisen to exploit those data. Using the interactions of transient waves with leaks, the detection, location, and quantification of leakage using a combination of transient analysis and inverse mathematics is possible using inverse transient analysis (ITA). This paper presents further development of ITA and experimental observations for leak detection in a laboratory pipeline. The effects of data and model error on ITA results have been explored including strategies to minimize their effects using model error compensation techniques and ITA implementation approaches. The shape of the transient is important for successful application of ITA. A rapid input transient (which may be of small magnitude) contains maximum system response information, thus improving the uniqueness and quality of the ITA solution. The effect of using he...
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paper_title: Leakage Zone Identification in Large-Scale Water Distribution Systems Using Multiclass Support Vector Machines

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AbstractThis paper presents a new method for identifying leakage zones of water distribution systems. A large water network is first divided into a number of zones. The zone number is used as the category label of the multiclass support vector machine (M-SVM), which is trained with the data set generated by simulation of the possible leakages using a hydraulic model. The trained M-SVM is used as the leakage zone identification model and applied to determine the likely leakage zones with the observed field data. Two case studies are presented in this paper to demonstrate the effectiveness of the method. The results indicate that this method has many unique advantages in solving the nonlinear and high-dimensional pattern recognition problem with a small sample data set. Together with the method of pressure-dependent leakage detection (PDLD), the proposed approach enables engineers to improve the effectiveness and efficiency of leakage detection for large water distribution systems.
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paper_title: Transient Test-Based Technique for Leak Detection in Outfall Pipes

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A technique is proposed for leak detection and evaluation in outfall pipes based on properties of transient pressure waves. Transients are caused by an increase of the piezometric head at the initial section of the outfall pipe. Since high overpressures are not necessary for the success of the technique and simple equipment is required, tests may be repeated periodically to check the state of the pipe. In order to verify the possibility of locating a possible leak on the basis of the results of transient tests, the effects of a leak on wave propagation from the numerical point of view are discussed first. A first-order formula for preliminary evaluation of the discharge behavior of the leak is also given. Results of some laboratory tests carried out on a long pipe are shown in order to confirm the reliability and validity of the proposed technique. Inverse transient calculations are proved to be able to provide precise information about the characteristics of the leak.
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paper_title: Gas Leakage Fault Detection of Pneumatic Pipe System Using Neural Networks

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This paper is concerned with gas leakage fault detection of a pneumatic pipe system using a neural network filter. In modern plants, the ability to detect and identify gas leakage faults is becoming increasingly important. The main difficulty to detect gas leakage faults by sound signals lies in that the practical plants are usually very noisy. In this research, neural networks are used as nonlinear filters to eliminate noise and raise the signal noise ratio of the sound signal. Neural networks have a self-learning ability. This ability can be utilized to build a self-adaptive nonlinear filter. By learning from practical samples of noise and adjusting coefficients of connection weights of neural networks, a neural network filter can predict the future sample values of noise based on present and previous sample values. The predicted error between predicted values and practical ones constitutes output of the filter. If the predicted error is zero, then there is no leakage. If the predicted error is greater than a certain value, then there is a leakage fault. Through application to practical pneumatic systems, it is verified that nonlinear filters with neural networks was effective in gas leakage detection from noise background.
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paper_title: Leak Detection and Calibration Using Transients and Genetic Algorithms

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Leak detection and calibration of pipe internal roughnesses in a water distribution network are significant issues for water authorities around the world. Computer simulation of water distribution systems to determine the location and size of leaks is emerging as an important tool. A major uncertainty in developing computer models is the condition of the interior of the pipes in the network, especially if they are old. An innovative technique for leak detection and calibration called the inverse transient technique has been recently developed. This paper uses the genetic algorithm (GA) technique in conjunction with the inverse transient method to detect leaks and friction factors in water distribution systems. A continuous variable representation has been developed for the GA coding scheme in this paper. Two new GA operators for crossover and mutation are also introduced. The inverse transient method using the GA technique is effective at finding leakage locations and magnitudes while simultaneously findi...
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paper_title: Pressure waves as a tool for leak detection in closed conduits

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In recent decades, growing water demand and a scarcity of easily exploitable high-quality water sources has reinvigorated interest in the further development of already stressed groundwater resources. Since leakage reduction often means the acquisition of new high-quality water resources, utility managers are realizing that water loss must be considered in plans to extend water supply and leak detection is now perceived as a money-saving expense. Among leak detection methodologies, those based on transient analysis can be some of the fastest and cheapest. This article briefly outlines the properties of pressure waves in closed single pipe systems. Past findings from the analysis of pressure signals within the time domain framework are reviewed and time series of pressure variations acquired in laboratory experiments at one measurement section are examined. Emphasis is placed on the analysis of transient test results in the frequency domain and the use of the wavelet transform for interpreting pressure sig...
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paper_title: LEAK DETECTION IN SIMULATED WATER PIPE NETWORKS USING SVM

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The detection and location of leaks in water pipe networks is a significant problem, which would benefit from more effective solutions. The information about the presence and location of leaks in a pipe network could be contained in the distribution of pressure or flow values at various points in the network; however, the information is encoded in such a way that its extraction is a complex inverse engineering problem. Such problems can be solved effectively through the use of pattern recognition techniques such as artificial neural networks ANNs or support vector machines SVMs. This article presents a method of using SVM analysis to interpret the data obtained by a collection of pressure sensors or flow-measuring devices monitoring a pipe network in order to obtain information about the location and size of leaks in the network.
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paper_title: Leak detection in petroleum pipelines using a fuzzy system

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A methodology for pipeline leakage detection using a combination of clustering and classification tools for fault detection is presented here. A fuzzy system is used to classify the running mode and identify the operational and process transients. The relationship between these transients and the mass balance deviation are discussed. This strategy allows for better identification of the leakage because the thresholds are adjusted by the fuzzy system as a function of the running mode and the classified transient level. The fuzzy system is initially off-line trained with a modified data set including simulated leakages. The methodology is applied to a small-scale LPG pipeline monitoring case where portability, robustness and reliability are amongst the most important criteria for the detection system. The results are very encouraging with relatively low levels of false alarms, obtaining increased leakage detection with low computational costs. D 2005 Elsevier B.V. All rights reserved.
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paper_title: Leakage detection and location in water distribution systems using a fuzzy-based methodology

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Loss of water due to leakage is a common phenomenon observed practically in all water distribution systems (WDS). However, the leakage volume can be reduced significantly if the occurrence of leakage is detected within minimal time after its occurrence. This paper proposes a novel methodology to detect and diagnose leakage in WDS. In the proposed methodology, a fuzzy-based algorithm has been employed that incorporates various uncertainties into different WDS parameters such as roughness, nodal demands, and water reservoir levels. Monitored pressure in different nodes and flow in different pipes have been used to estimate the degree of membership of leakage and its severity in terms of index of leakage propensity (ILP). Based on the degrees of leakage memberships and the ILPs, the location of the nearest leaky node or leaky pipe has been identified. To demonstrate the effectiveness of the proposed methodology, a small distribution network was investigated which showed very encouraging results. The proposed...
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paper_title: Using neural networks to monitor piping systems

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The paper proposes a state estimation technique, which uses Artificial Neural Networks (ANN) to monitor the status of piping networks carrying hazardous fluids, in order to identify and locate spills and leakages. A Multilayer Perceptron ANN is used to process pressure and flow rate information coming from a limited number of sensors distributed across the network. The ANN is trained on different sets of input data, which characterize several states of the fluid network under normal and abnormal operating conditions. During the running phase, it acts as a classifier in order to estimate the actual system status and pinpoint leaks, based on available information, thereby solving the stated inverse problem. A two-level architecture is selected, composed of a main ANN at the first level, to identify the branch in which the leakage occurs, and several branch-specific ANNs at the second-level to accurately estimate the magnitude and location of the leaks. After describing the proposed methodology and the system architecture, we present a realistic application example in order to show the technique's potential.
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paper_title: Statistical models for the analysis of water distribution system pipe break data

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The deterioration of pipes leading to pipe breaks and leaks in urban water distribution systems is of concern to water utilities throughout the world. Pipe breaks and leaks may result in reduction in the water-carrying capacity of the pipes and contamination of water in the distribution systems. Water utilities incur large expenses in the replacement and rehabilitation of water mains, making it critical to evaluate the current and future condition of the system for maintenance decision-making. This paper compares different statistical regression models proposed in the literature for estimating the reliability of pipes in a water distribution system on the basis of short time histories. The goals of these models are to estimate the likelihood of pipe breaks in the future and determine the parameters that most affect the likelihood of pipe breaks. The data set used for the analysis comes from a major US city, and these data include approximately 85,000 pipe segments with nearly 2500 breaks from 2000 through 2005. The results show that the set of statistical models previously proposed for this problem do not provide good estimates with the test data set. However, logistic generalized linear models do provide good estimates of pipe reliability and can be useful for water utilities in planning pipe inspection and maintenance.
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paper_title: A survey on gas leak detection and localization techniques

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Abstract Gas leaks can cause major incidents resulting in both human injuries and financial losses. To avoid such situations, a considerable amount of effort has been devoted to the development of reliable techniques for detecting gas leakage. As knowing about the existence of a leak is not always enough to launch a corrective action, some of the leak detection techniques were designed to allow the possibility of locating the leak. The main purpose of this paper is to identify the state-of-the-art in leak detection and localization methods. Additionally we evaluate the capabilities of these techniques in order to identify the advantages and disadvantages of using each leak detection solution.
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paper_title: Comparing risk of failure models in water supply networks using ROC curves

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Abstract The problem of predicting the failure of water mains has been considered from different perspectives and using several methodologies in engineering literature. Nowadays, it is important to be able to accurately calculate the failure probabilities of pipes over time, since water company profits and service quality for citizens depend on pipe survival; forecasting pipe failures could have important economic and social implications. Quantitative tools (such as managerial or statistical indicators and reliable databases) are required in order to assess the current and future state of networks. Companies managing these networks are trying to establish models for evaluating the risk of failure in order to develop a proactive approach to the renewal process, instead of using traditional reactive pipe substitution schemes. The main objective of this paper is to compare models for evaluating the risk of failure in water supply networks. Using real data from a water supply company, this study has identified which network characteristics affect the risk of failure and which models better fit data to predict service breakdown. The comparison using the receiver operating characteristics (ROC) graph leads us to the conclusion that the best model is a generalized linear model. Also, we propose a procedure that can be applied to a pipe failure database, allowing the most appropriate decision rule to be chosen.
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paper_title: Bayesian Belief Networks for predicting drinking water distribution system pipe breaks

paper_content:

Abstract In this paper, we use Bayesian Belief Networks (BBNs) to construct a knowledge model for pipe breaks in a water zone. To the authors’ knowledge, this is the first attempt to model drinking water distribution system pipe breaks using BBNs. Development of expert systems such as BBNs for analyzing drinking water distribution system data is not only important for pipe break prediction, but is also a first step in preventing water loss and water quality deterioration through the application of machine learning techniques to facilitate data-based distribution system monitoring and asset management. Due to the difficulties in collecting, preparing, and managing drinking water distribution system data, most pipe break models can be classified as “statistical–physical” or “hypothesis-generating.” We develop the BBN with the hope of contributing to the “hypothesis-generating” class of models, while demonstrating the possibility that BBNs might also be used as “statistical–physical” models. Our model is learned from pipe breaks and covariate data from a mid-Atlantic United States (U.S.) drinking water distribution system network. BBN models are learned using a constraint-based method, a score-based method, and a hybrid method. Model evaluation is based on log-likelihood scoring. Sensitivity analysis using mutual information criterion is also reported. While our results indicate general agreement with prior results reported in pipe break modeling studies, they also suggest that it may be difficult to select among model alternatives. This model uncertainty may mean that more research is needed for understanding whether additional pipe break risk factors beyond age, break history, pipe material, and pipe diameter might be important for asset management planning.
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paper_title: Leak Estimation in Water Distribution Systems by Statistical Analysis of Flow Readings

paper_content:

A new method is presented for detecting the magnitude of leaks in small residential service zones (under 1,000 homes) of a drinking water distribution system. It is assumed that continuous measurements of flow rates through the main supply line into a residential service zone are available during periods of low use. The sample mean and variance from the set of measured flow rates are computed as the set is truncated progressively from below. Trajectories of the sample statistics and their derivatives are plotted versus the level of data truncation. In the presence of leaks, these trajectories diverge from their expected theoretical path when plotted on a standardized graph derived from a mixed truncated normal distribution. The point of departure on the standardized graph indicates where the truncation threshold matches the maximum rate of network leakage. A performance limit for the proposed method is derived to account for network size and time averaging. Several examples, based on observed and simulated pipe flows, demonstrate application of the leak detection method.
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paper_title: An analysis of pipe breakage in urban water distribution networks

paper_content:

The rates of pipe breakage with increasing pipe diameter and times are investigated. Failure rates for cast-iron pipe are found to decrease with increasing diameter. Changes in pipe failure rates for the various modes of failures are examined in detail. Asbestos-cement and cast-iron pipe overall failure rates are found to increase with time, but for different reasons. Analysis of the modes of failure shows that joint failure is predominant for cast-iron pipe systems with bolted and universal joints whereas the predominant mode of failure for asbestos-cement pipe systems is circumferential cracking. Key words: asbestos cement, cast iron, cracking, diameter, failure rate, joint, regression analysis.
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paper_title: Leak detection using instantaneous frequency analysis

paper_content:

Leaking pipes are a primary concern for water utilities around the globe as they compose a major portion of losses. Contemporary interest surrounding leaks is well documented and there is a proliferation of leak detection techniques. Although the reasons for these leaks are well known, some of the current methods for leak detection and location are either complicated, inaccurate and most of them are time consuming. Transient analyses offer a plausible route towards leak detection due to their robustness and simplicity. These approaches use the change of pressure response of the fluid in a pipeline to identify features. The method used in the current study employ a single pressure transducer to obtain the time domain signal of the pressure transient response caused by a sudden opening and closing of a solenoid valve. The device used is fitted onto a standard UK hydrant and both cause a pressure wave and acquire the pressure history. The work described here shows that the analysis using Hilbert transform (HT), Hilbert Huang transform (HIHT) and EMD based method is a promising tool for leak detection and location in the pipeline network. In the first part of the work, the analysis of instantaneous characteristics of transient pressure signal has been calculated using HT and HHT for both simulated and experimental data. These instantaneous properties of the signals are shown to be capable of detecting the reflection from the features of the pipe such as leakages and outlet. When tested with leak different locations, the processed results still show the existing of the features in the system. In the second part of the work, the study is based on newly method of analysing nonstationary data called empirical mode decomposition (EMD) for instantaneous frequency calculation for leak detection. First, the pressure signals were filtered in order to remove the noise using EMD. Then the instantaneous frequency was calculated and compared using different methods. With this method, it is possible to identify the leaks and also the features in the pipeline network. These were tested at different locations of a real water distribution system in the Yorkshire Water region.
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paper_title: Wavelets for the Analysis of Transient Pressure Signals for Leak Detection

paper_content:

Transient tests can be reliably used for the diagnosis of pressurized pipe systems. As a matter of fact, the pressure signals acquired during these tests can reveal the presence of anomalies, e.g., leaks, since any irregularity in the pipe gives rise to reflected waves which in turn create discontinuities in the observed signal at the measurement section. In order to make the most of the interpretation of the pressure signals, as well as to improve the effectiveness of the location of leaks, wavelet analysis—a powerful tool within the realm of harmonic analysis—can be used. It aids in the diagnosis of pressure pipe systems by better exposing pressure signal discontinuities and precisely determining the arrival time of the pressure waves reflected by leaks, thus locating the leak itself. Since many wavelet transforms are available and the choice is driven by the specific application, both continuous and discrete wavelet transforms are considered in the paper, comparing different mother wavelets. Then the r...
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paper_title: Detection of leak acoustic signal in buried gas pipe based on the time―frequency analysis

paper_content:

Abstract A time–frequency technique for locating leaks in buried gas distribution pipes involves the use of the cross-correlation on two measured acoustic signals on either side of a leak. This technique can be problematic for locating leaks in steel pipes, as the acoustic signals in these pipes are generally narrow-band and low frequency. The effectiveness of the time–frequency technique for detecting leaks in steel pipes was investigated experimentally in an earlier study. The object of this paper is to identify the characteristics of this dispersive acoustic wave through analysis of the cut-off frequency by using the time–frequency method experimentally and BEM (boundary element method) theoretically for the development of an experimental tool to analyze the leak signals in steel pipe. The tool is based on experimental work and theoretical formulation of wave propagation in a fluid-filled pipe. This tool uses the time–frequency method to explain some of the features of wave propagation measurements made in gas pipes. Leak noise signals are generally passed through a time–frequency filter for detection of impulse signal related leakage.
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paper_title: Standing Wave Difference Method for Leak Detection in Pipeline Systems

paper_content:

The current paper focuses on leakage detection in pipe systems by means of the standing wave difference method (SWDM) used for cable fault location in electrical engineering. This method is based on the generation of a steady-oscillatory flow in a pipe system, by the sinusoidal maneuver of a valve, and the analysis of the frequency response of the system for a certain range of oscillatory frequencies. The SWDM is applied to several configurations of pipe systems with different leak locations and sizes. A leak creates a resonance effect in the pressure signal with a secondary superimposed standing wave. The pressure measurement and the spectral analysis of the maximum pressure amplitude at the excitation site enable the identification of the leak frequencies and, consequently, the estimation of the leak approximate location. Practical difficulties of implementation of this technique in real life systems are discussed.
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paper_title: Frequency domain analysis for detecting pipeline leaks

paper_content:

This paper introduces leak detection methods that involve the injection of a fluid transient into the pipeline, with the resultant transient trace analyzed in the frequency domain. Two methods of leak detection using the frequency response of the pipeline are proposed. The inverse resonance method involves matching the modeled frequency responses to those observed to determine the leak parameters. The peak-sequencing method determines the region in which the leak is located by comparing the relative sizes between peaks in the frequency response diagram. It was found that a unique pattern was induced on the peaks of the frequency response for each specific location of the leak within the pipeline. The leak location can be determined by matching the observed pattern to patterns generated numerically within a lookup table. The procedure for extracting the linear frequency response diagram, including the optimum measure- ment position, the effect of unsteady friction, and the way in which the technique can be extended into pipeline networks, are also discussed within the paper.
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paper_title: Pipeline Network Features and Leak Detection by Cross-Correlation Analysis of Reflected Waves

paper_content:

This paper describes progress on a new technique to detect pipeline features and leaks using signal processing of a pressure wave measurement. Previous work (by the present authors) has shown that the analysis of pressure wave reflections in fluid pipe networks can be used to identify specific pipeline features such as open ends, closed ends, valves, junctions, and certain types of bends. It was demonstrated that by using an extension of cross-correlation analysis, the identification of features can be achieved using fewer sensors than are traditionally employed. The key to the effectiveness of the technique lies in the artificial generation of pressure waves using a solenoid valve, rather than relying upon natural sources of fluid excitation. This paper uses an enhanced signal processing technique to improve the detection of leaks. It is shown experimentally that features and leaks can be detected around a sharp bend and up to seven reflections from features/leaks can be detected, by which time the wave has traveled over 95 m. The testing determined the position of a leak to within an accuracy of 5%, even when the location of the reflection from a leak is itself dispersed over a certain distance and, therefore, does not cause an exact reflection of the wave.
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paper_title: Spectral analysis of leak detection in a zigzag pipeline: A filter diagonalization method-based algorithm application

paper_content:

Abstract Pipeline monitoring plays a key role in many industrial processes and human activities, in particular, for the management of water resources. Spectral analysis response, used for leak detection, is generally based on fast Fourier transform (FFT). The aim of this paper is to develop an alternative method based on filter diagonalization method (FDM), mainly used in nuclear magnetic resonance, in order to overcome limitations of FFT approach. Thanks to its robustness, FDM allows difficulties created by zigzag pipeline, buried water tubes and in general by the presence of noisily boundary conditions to be solved. Moreover, another objective is reached by reducing FFT recovery error for narrow pipelines. An experimental facility has been constructed to show the results of this alternative approach.
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paper_title: Leak Detection in Pipes by Frequency Response Method

paper_content:

The frequency response method is used to determine the location and rate of leakage in open loop piping systems. A steady-oscillatory flow, produced by the periodic opening and closing of a valve, is analyzed in the frequency domain by using the transfer matrix method, and a frequency response diagram at the valve is developed. For a system with leaks, this diagram has additional resonant pressure amplitude peaks (herein referred to as the secondary pressure amplitude peaks) that are lower than the resonant pressure amplitude peaks (herein called primary amplitude peaks) for the system with no leaks. Several piping systems are successfully analyzed for all practical values of the friction factor to detect and locate individual leaks of up to 0.5% of the mean discharge. The method, requiring the measurement of pressure and discharge fluctuations at only one location, has the potential to detect leaks in real-life pipe systems conveying different types of fluids, such as water, petroleum, and so on.
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paper_title: Find that leak

paper_content:

Digital signal processing can help cut losses from leaking water mains. The authors explain how one new development, sponsored by Thames Water, is helping it in the battle to locate leaks more quickly and reliably. From the outset their aim was to develop a `virtual' instrument approach based on a standard personal computer (PC). In this way, as the knowledge base increases and further improvements are made, software upgrades can be implemented on the same hardware platform. The use of a standard commercially available sound card fits in with this approach. In practice the software development proceeded in two main stages: an initial programme of algorithm development, followed by real-time algorithm implementation and graphical user interface (GUI).
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paper_title: Impedance Method for Leak Detection in Zigzag Pipelines

paper_content:

Transportation of liquids is a primary aspect of human life. The most important infrastructure used accordingly is the pipeline. It serves as an asset for transporting different liquids and strategic goods. The latter are for example: chemical substances, oil, gas and water. Thus, it is necessary to monitor such infrastructures by means of specific tools. Leakage detection methods are used to reveal liquid leaks in pipelines for many applications, namely, waterworks, oil pipelines, industry heat exchangers, etc.. The configuration of pipelines is a key issue because it impacts on the effectiveness of the method to be used and, consequently, on the results to be counterchecked. This research illustrated an improvement of the impedance method for zigzag pipeline by carrying out an experimental frequency analysis that has been compared with other methods based on frequency response. Hence, the impedance method is generally used for simple (straight) pipeline configurations because complicated pipelines with many curves introduce difficulties and major uncertainties in the calculation of characteristic impedance and in the statement of boundary conditions. The paper illustrates the case of a water pipeline where the leakage is acquired thanks to pressure transducers.
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paper_title: Experimental verification of the frequency response method for pipeline leak detection

paper_content:

This paper presents an experimental validation of the frequency response method for pipeline leak detection. The presence of a leak within the pipe imposes a periodic pattern on the resonant peaks of the frequency response diagram. This pattern can be used as an indicator of leaks without requiring the “no-leak” benchmark for comparison. In addition to the experimental verification of the technique, important issues, such as the procedure for frequency response extraction and methods for dealing with frequency-dependent friction are considered in this paper. In this study, transient signals are generated by a side-discharge solenoid valve. Non-linearity errors associated with large valve movements can be prevented by a change in the input parameter to the system. The optimum measuring and generating position for two different system boundary configurations—a symmetric and an antisymmetric system—are discussed in the paper and the analytical expression for the leak-induced pattern in these two cases is derived
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paper_title: A technical note on the inclusion of pressure dependent demand and leakage terms in water supply network models

paper_content:

Abstract This note suggests a technique for including pressure dependent demand and leakage terms in simulation models for water distribution systems. Empirical functions are used to relate consumer outflows and leakage losses to the network pressures and the inclusion of these functions in the mathematical formulation of the network analysis problem is described. An application to an existing distribution system is presented where it is shown that the extended network model proposed leads to more realistic simulation results when the network pressures are too low to provide specified consumer demands, or high enough to cause significant leakage losses. It is also found that the computational requirements of network analysis and simulation are not significantly affected by the inclusion of the additional terms.
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paper_title: Pressure-Dependent Leak Detection Model and Its Application to a District Water System

paper_content:

Cost-effective reduction of water loss is a compelling but challenging task for water utilities. This paper presents a model-based optimization method for leakage detection of water distribution systems. Leakage hotspots are assumed to exist at the model nodes identified. Leakage is represented as pressure-dependent demand simulated as emitter flows at selected model nodes. The leakage detection method is formulated to optimize the leakage node locations and their associated emitter coefficients such that the differences between the model predicted and the field observed values for pressure and flow are minimized. The optimization problem is solved by using a competent genetic algorithm. The leakage detection method is developed as an add-on feature of the optimization-based model calibration tool. This enables engineers to undertake leakage hotspot optimization as an independent task or combine the task with hydraulic model calibration, subject to suitably varied field data. Two case studies are discusse...
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paper_title: Leakage detection algorithm integrating water distribution networks hydraulic model

paper_content:

Paper presented at SimHydro 2017: Choosing the right model in applied hydraulics, 14-16 June 2017, Sophia Antipolis, France
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paper_title: Parameter-Less Remote Real-Time Control for the Adjustment of Pressure in Water Distribution Systems

paper_content:

Copyright: 2017 ASCE - American Soc Civil Engineers. Due to copyright restrictions, the attached PDF file only contains the abstract of the full text item. For access to the full text item, please consult the publisher's website. The definitive version of the work is published in Journal of Water Resources Planning and Management, 143(9), pp 1-12
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paper_title: Development of Pipeline Leak Detection Technologies

paper_content:

New development continues in pipeline leak detection technologies in order to meet the increasing demand of the oil, gas, chemical and water industry. After a review of the available technologies, this paper discusses the advances made in two key technologies: statistical volume balance and negative pressure wave.
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paper_title: Progress in practical prediction of pressure: leakage, pressure: burst frequency and pressure: consumption relationships

paper_content:

Substantial advances have been made in the last decade in the development of practical methods for understanding and predicting how leakage rates and burst frequencies in distribution systems, and some elements of consumption, are influenced by pressure. Members of the Pressure Management Team of the Water Losses Task Force continue to try to improve the practical methods available for analysis and prediction. The combination of existing and new material is presented under four principal topic headings: • Predicting pressure: leakage rate relationships using Power Law exponents • Extending the range of operating pressures for the UARL formula • New information on pressure: consumption relationships • Pressure: new burst frequency relationships The paper concludes with a brief listing of some practical research topics that could usefully be pursued, and explains that, by using software specifically designed for pressure management, practical predictions can usually be made rapidly without the need for network analysis models.
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paper_title: An overview of pipeline leak detection and location systems

paper_content:

Leak detection in transmission pipelines is crucially important for safe operation. Delay in detecting leaks leads to loss of property and human life in fire hazards and loss of valuable material. Leaking of methane and hydrocarbon gas causes negative impacts on the eco system such as global warming and air pollution. Pipeline leak detection systems play a key role in minimization of the probability of occurrence of leaks and hence their impacts. Today there are many available technologies in the domain of leak detection. This paper provides an overview on external and internal leak detection and location systems and a summary of comparison regarding performance of each system.
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paper_title: Pressure control for leakage minimization in water supply networks Part 1: Single period models

paper_content:

The issue of minimizing leakage in water supply networks by appropriate control of the settings of pressure-reducing valves is addressed. The problem is first formulated as a non-linear, non-convex optimization problem. The limitations of iterative linearization are then discussed. Alternative linearized models based on separable programming are presented. Results of case studies to assess the efficacy and computational efficiency of the proposed models are presented and discussed.
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paper_title: A survey on gas leak detection and localization techniques

paper_content:

Abstract Gas leaks can cause major incidents resulting in both human injuries and financial losses. To avoid such situations, a considerable amount of effort has been devoted to the development of reliable techniques for detecting gas leakage. As knowing about the existence of a leak is not always enough to launch a corrective action, some of the leak detection techniques were designed to allow the possibility of locating the leak. The main purpose of this paper is to identify the state-of-the-art in leak detection and localization methods. Additionally we evaluate the capabilities of these techniques in order to identify the advantages and disadvantages of using each leak detection solution.
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paper_title: Acoustical Characteristics of Leak Signals in Plastic Water Distribution Pipes

paper_content:

Abstract Acoustical characteristics of leak signals in plastic pipes were investigated in this study for several types of leaks simulated under controlled conditions at an experimental site. The investigation included the characterization of frequency content of sound or vibration signals as a function of leak type, flow rate, pipe pressure and season, the determination of the attenuation rate, and the variation of propagation velocity with frequency. The information presented in this paper for the acoustic characteristics of leak signals will help leak detection professionals in the selection of appropriate instrumentation, the design of appropriate measurement procedures, and in the case of propagation velocity, in accurately locating leaks using the cross-correlation method.
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paper_title: Negative pressure wave based pipeline Leak Detection: Challenges and algorithms

paper_content:

Negative pressure wave is a popular method to detect the occurrence and location of leak incidents in oil/gas pipeline. Three core technical challenges and related algorithm are discussed in this paper. The first is data quality. The balance between noise level and locating precision is discussed in filter design. The second one is dynamic slope in anomaly detection, whence a bi-SPC (Static Process Control) algorithms is proposed to make the threshold be adaptive. The third one is the false alarm caused normal working condition changes. Multiple-sensor paring algorithms is presented. With these algorithms, the robustness and locating precision of LDS (Leak Detection System) can be ensured.
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paper_title: Study on New Methods of Improving the Accuracy of Leak Detection and Location of Natural Gas Pipeline

paper_content:

As negative pressure wave is applied to leak detection and location of natural gas pipeline, the key is how to realize accurate measurement of propagation velocity of pressure wave and time difference. However, there exists problem of lower accuracy in negative pressure wave method. Aiming at the problems of velocity measurement formula with low precision and low accuracy of leaking location, a modified velocity measurement formula is proposed. In addition, based on the theory of singularity detection of wavelet transform, the singular characteristic of the transform wave caused by pipeline leakage is detected accurately. The experimental results show that it can achieve leak detection and location of natural gas with higher accuracy through these methods.
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paper_title: Leak location using blind system identification in water distribution pipelines

paper_content:

This paper presents a new leak location method without knowledge of pipe length in water distribution pipes. In conventional leak location surveys using acoustic signals in buried water distribution pipelines, the most widely used techniques are based on the correlation technique. The prerequisite of the method is that the accurate length of pipeline between two detection points is known. However, in practice, this prerequisite is not always satisfied. Based on the fact that the acquired acoustic signals contain the characteristics related to the two propagation channels, the blind system identification strategy is applied to estimate the transmission performances of the two acoustic channels. Due to the long impulse response of acoustic channel, the overlap-save and cross-correlation fitting technique are utilized in blind system identification to estimate the acoustic channels under a built constraint condition. In order to avoid converging to the local minima, the genetic algorithm is adopted to optimize the channel identification. The times due to the propagation of the leak source signal traveling from the leak point to either sensor are extracted from the identified acoustic channels. Consequently, for leak location, the pipe length is no longer a prerequisite. The practical location results show the validness of the proposed scheme.
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paper_title: Small scale windmill

paper_content:

In this letter the authors report experimental results on an optimized small scale piezoelectric windmill, which can solve the problems associated with autonomous sensor networks in outdoor, remote or inaccessible locations. The whole structure of the windmill is made of plastic, and it utilizes 18 piezoelectric bimorphs which makes this design extremely cost effective. The windmill was tested at average wind speed of 10miles∕h and it provided 5mW continuous power. The threshold wind speed for the windmill was found to be of the order of 5.4miles∕h. Further, the authors present analysis on two other windmill structures which illustrate the design parameters required for small scale windmill.
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paper_title: Focal design issues affecting the deployment of wireless sensor networks for pipeline monitoring

paper_content:

Wireless sensor networks (WSNs) are a target technology for oil and gas pipeline monitoring because they offer benefits of low cost, ease of deployment and ability to cater for data acquisition at great spatial and temporal scales. In order for WSN to achieve trademark performance in remote monitoring of pipelines, and surpass the performance of present-day traditional monitoring systems, certain design requirements must be met. In this paper, we identify vital design issues that must be considered to facilitate the employment of WSN for pipeline monitoring. We classify these design issues into five different categories namely; sensing modality, power efficiency, energy harvesting, network reliability and localization. In addition, we discuss the concept of cooperative communication for pipeline-monitoring sensor networks deployed in sub-sea environments. We also study the employment of sensor networks for monitoring underground pipelines. Our findings are based on extensive study of the recent literature and comprehensive survey of existing WSN technologies. The WSN design considerations presented in this paper are particularly prolific for pipeline monitoring scenarios, they can however be easily extended to other oil and gas infrastructures. For example; well-head and heat exchanger monitoring, oil platform process monitoring, monitoring of natural gas storage facilities and data collection on coastal infrastructures that could support oil and gas exploration.
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paper_title: Smart water meter system for user-centric consumption measurement

paper_content:

Water scarcity and water stress issues pose a serious threat to the global population. The traditional way of manual meter reading is furthermore inconvenient and time consuming, and it wastes resources. This method is also unable to manage the sustainable water resources effectively since it requires efficient, accurate and reliable monitoring techniques that enable the utilities sector and consumers to know the level of water consumption in real-time. Real-time smart water meters that can be monitored by the user are essential and constitute a key component of the water management system. A smart watermonitoring system will make users mindful of their water consumption and help them to reduce their water usage. At the same time, users will be alerted to abnormal water usage to reduce water loss. This paper introduces the water management system based on wireless sensor networks (WSN). The system uses the IEEE 802.15.4 standard embedded in ContikiOS LibCoAP as an open-source application to create a robust and intelligent system. Visualisation and monitoring of the system is achieved following the development of a web-based system and through Pandora FMS.
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paper_title: New measures for characterizing the significance of nodes in wireless ad hoc networks via localized path-based neighborhood analysis

paper_content:

The synergy between social network analysis and wireless ad hoc network protocol design has recently created increased interest for developing methods and measures that capture the topological characteristics of a wireless network. Such techniques are used for the design of routing and multicasting protocols, for cooperative caching purposes and so on. These techniques are mandatory to characterize the network topology using only limited, local connectivity information—one or two hop information. Even though it seems that such techniques can straightforwardly be derived from the respective network-wide techniques, their design presents significant challenges since they must capture rich information using limited knowledge. This article examines the issue of finding the most central nodes in neighborhoods of a given network with directed or undirected links taking into account only localized connectivity information. An algorithm that calculates the ranking, taking into account the N-hop neighborhood of each node is proposed. The method is compared to popular existing schemes for ranking, using Spearman’s rank correlation coefficient. An extended, faster algorithm which reduces the size of the examined network is also described.
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paper_title: Nondestructive monitoring of a pipe network using a MEMS-based wireless network

paper_content:

A MEMS-based wireless sensor network (WSN) is developed for nondestructive monitoring of pipeline systems. It incorporates ::: MEMS accelerometers for measuring vibration on the surface of a pipe to determine the change in water pressure ::: caused by rupture and the damage location. This system enables various sensor boards and camera modules to be daisychained ::: underground and to transmit data with a shared radio board for data uplink. Challenges include reliable long-range ::: communication, precise time synchronization, effective bandwidth usage, and power management. The low-cost MEMS ::: technology, saved wiring cost, and simple installation without destructive modification enable large-scale deployment at ::: an affordable cost.
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paper_title: A Proposed Scalable Design and Simulation of Wireless Sensor Network-Based Long-Distance Water Pipeline Leakage Monitoring System

paper_content:

Anomalies such as leakage and bursts in water pipelines have severe consequences for the environment and the economy. To ensure the reliability of water pipelines, they must be monitored effectively. Wireless Sensor Networks (WSNs) have emerged as an effective technology for monitoring critical infrastructure such as water, oil and gas pipelines. In this paper, we present a scalable design and simulation of a water pipeline leakage monitoring system using Radio Frequency IDentification (RFID) and WSN technology. The proposed design targets long-distance aboveground water pipelines that have special considerations for maintenance, energy consumption and cost. The design is based on deploying a group of mobile wireless sensor nodes inside the pipeline and allowing them to work cooperatively according to a prescheduled order. Under this mechanism, only one node is active at a time, while the other nodes are sleeping. The node whose turn is next wakes up according to one of three wakeup techniques: location-based, time-based and interrupt-driven. In this paper, mathematical models are derived for each technique to estimate the corresponding energy consumption and memory size requirements. The proposed equations are analyzed and the results are validated using simulation.
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paper_title: SmartPipes: Smart Wireless Sensor Networks for Leak Detection in Water Pipelines

paper_content:

Asset monitoring, specifically infrastructure monitoring such as water distribution pipelines, is becoming increasingly critical for utility owners who face new challenges due to an aging network. In the UK alone, during the period of 2009–2010, approximately 3281 mega litres (106) of water were wasted due to failure or leaks in water pipelines. Various techniques can be used for the monitoring of water distribution networks. This paper presents the design, development and testing of a smart wireless sensor network for leak detection in water pipelines, based on the measurement of relative indirect pressure changes in plastic pipes. Power consumption of the sensor nodes is minimised to 2.2 mW based on one measurement every 6 h in order to prolong the lifetime of the network and increase the sensor nodes’ compatibility with current levels of power available by energy harvesting methods and long life batteries. A novel pressure sensing method is investigated for its performance and capabilities by both laboratory and field trials. The sensors were capable of measuring pressure changes due to leaks. These pressure profiles can also be used to locate the leaks.
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paper_title: Real-time Dynamic Hydraulic Model for Water Distribution Networks: Steady State Modelling

paper_content:

Proceedings of the Sixth IASTED International Conference, Environment and Water Resource Management (AfricaEWRM 2016), 5-7 September 2016 Gaborone, Botswana.
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paper_title: Wireless sensor networks testbed: ASNTbed

paper_content:

Wireless sensor networks (WSNs) have been used in different types of applications and deployed within various environments. Simulation tools are essential for studying WSNs, especially for exploring large-scale networks. However, WSN testbeds are still required for further testing before the real implementation. In this paper we propose an indoor testbed which is built on the ceiling board of the demonstration room. The purpose of this testbed is to evaluate various types of algorithms and protocols before using them in real world applications. This paper focuses on how to implement such testbed and what are the main challenges that we experienced while implementing the ASNTbed (Advanced Sensor Networks Testbed) and how to solve them. This paper can be considered as a guideline to help other researchers and developers to implement similar testbed.
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paper_title: A survey on routing protocols for wireless sensor networks

paper_content:

Recent advances in wireless sensor networks have led to many new protocols specifically designed for sensor networks where energy awareness is an essential consideration. Most of the attention, however, has been given to the routing protocols since they might differ depending on the application and network architecture. This paper surveys recent routing protocols for sensor networks and presents a classification for the various approaches pursued. The three main categories explored in this paper are data-centric, hierarchical and location-based. Each routing protocol is described and discussed under the appropriate category. Moreover, protocols using contemporary methodologies such as network flow and quality of service modeling are also discussed. The paper concludes with open research issues. � 2003 Elsevier B.V. All rights reserved.
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paper_title: Wireless underground sensor networks : Research challenges

paper_content:

This work introduces the concept of a Wireless Underground Sensor Network (WUSN). WUSNs can be used to monitor a variety of conditions, such as soil properties for agricultural applications and toxic substances for environmental monitoring. Unlike existing methods of monitoring underground conditions, which rely on buried sensors connected via wire to the surface, WUSN devices are deployed completely belowground and do not require any wired connections. Each device contains all necessary sensors, memory, a processor, a radio, an antenna, and a power source. This makes their deployment much simpler than existing underground sensing solutions. Wireless communication within a dense substance such as soil or rock is, however, significantly more challenging than through air. This factor, combined with the necessity to conserve energy due to the difficulty of unearthing and recharging WUSN devices, requires that communication protocols be redesigned to be as efficient as possible. This work provides an extensive overview of applications and design challenges for WUSNs, challenges for the underground communication channel including methods for predicting path losses in an underground link, and challenges at each layer of the communication protocol stack. � 2006 Elsevier B.V. All rights reserved.
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paper_title: A Novel Energy-Aware Approach for Locating Leaks in Water Pipeline Using a Wireless Sensor Network and Noisy Pressure Sensor Data

paper_content:

We propose a novel energy-aware approach to detect a leak and estimate its size and location in a noisy water pipeline using least-squares and various pressure measurements in the pipeline network. The novelty in our work hinges on the fusion of the duty-cycling (DC) and data-driven (DD) strategies, both well-known techniques for energy reduction in a wireless sensor network (WSN). To maximize the information gain and minimize the energy consumed by the WSN, we first study the effects of (a) various levels of sensor measurement uncertainty and (b) the use of the smallest possible number of pressure sensors on the overall accuracy of our approach. Using the DD strategy only, a noisy environment, and a small number of sensors, the performance of our scheme shows that, for small leak sizes, the estimation error in both leak location and size becomes unacceptably high. Next, using as few sensors as possible for an acceptable accuracy, we fused the DD strategy with the DC one to minimize the sensing, processing, and communication energies. The fusion approach yielded a better performance with significant energy saving, even in noisy environments. EPANET was used to model the pipeline network and leak and MATLAB to implement, analyze, and evaluate our fusion approach.
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paper_title: MISE-PIPE : Magnetic induction-based wireless sensor networks for underground pipeline monitoring

paper_content:

Underground pipelines constitute one of the most important ways to transport large amounts of fluid (e.g. oil and water) through long distances. However, existing leakage detection techniques do not work well in monitoring the underground pipelines due to the harsh underground environmental conditions. In this paper, a new solution, the magnetic induction (MI)-based wireless sensor network for underground pipeline monitoring (MISE-PIPE), is introduced to provide low-cost and real-time leakage detection and localization for underground pipelines. MISE-PIPE detects and localizes leakage by jointly utilizing the measurements of different types of sensors that are located both inside and around the underground pipelines. By adopting an MI waveguide technique, the measurements of different types of the sensors throughout the pipeline network can be reported to the administration center in real-time. The system architecture and operational framework of MISE-PIPE is first developed. Based on the operational framework, research challenges and open research issues are then discussed.
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paper_title: Embedded Damage Detection in Water Pipelines Using Wireless Sensor Networks

paper_content:

This paper proposes a distributed real-time detection algorithm for detecting rupture events in water pipelines noninvasively. The purpose is to suppress not only unnecessary transmission but also local processing in order to save power without sacrificing sensitivity or specificity of the events of interest. All these goals are accomplished by adaptive thresholding, a cascaded wake-up chain, local processing, and aggressive power management. Experimental results show that the proposed algorithm achieves high sensitivity and high specificity while reducing the total energy consumption significantly.
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paper_title: Small-scale energy harvesting through thermoelectric, vibration, and radiofrequency power conversion

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As sensors for a wide array of applications continue to shrink and become integrated, increasing attention has been focused on creating autonomous devices with long-lasting power supplies. To achieve this, energy will have to be harvested from the sensors’ environment. An energy harvesting device can power the sensor either directly or in conjunction with a battery. Presented herein is a review of three types of energy harvesting with focus on devices at or below the cm3 scale. The harvesting technologies discussed are based on the conversion of temperature gradients, mechanical vibrations, and radiofrequency waves. Operation principles, current state of the art, and materials issues are presented. In addition, requirements and recent developments in power conditioning for such devices are discussed. Future challenges specific to miniaturization are outlined from both the materials and device perspectives.
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paper_title: A Wireless Sensor Network-Based Infrastructure for Real-Time and Online Pipeline Inspection

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The aim of this paper is to present a secure wireless sensor network-based infrastructure for fast and accurate detection of eventual leaks that might occur in multiphase pipelines (i.e., pipelines which carry simultaneously more than one fluid). The system is scalable to monitor long distances of pipelines. It consists of a newly designed low-cost pipeline set which is composed of an inner pipe that carries the multiphase fluid, surrounded by a second outer pipe that holds the leak detection unit. This latest comprises an air-ultrasonic sensor which continuously senses the presence of the leak. The location of the leak is determined by a bidirectional microphone. Both these sensors are interfaced to a wireless sensor module which performs control, signal processing, and transmission tasks. Hence, the second contribution of this paper is to provide a new secure and reliable communication protocol that takes into consideration the nature of the network in terms of packets patterns and hardware constraints of the communicating nodes. Online tests in a laboratory scale flow loop indicate that the system is capable to accurately determine the location of the leak and its rate (in 1/min) in fast response time for different scenarios of leaks.
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paper_title: A Simple Security Architecture for Smart Water Management System

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Abstract Water scarcity and water stress issues have become clear threat to the global population. This makes water management a critical aspect to ensure sustainable water. An efficient water management system requires thousands of constraint devices (sensors and/or actuators) to be deployed across the water distribution network to enable near-real time monitoring and control of the water grid components. Security at both the device and network level is critical to the operation of such a system. Although several IT security controls have developed over the past few decades, they cannot be used directly with such constraint devices. This is due to their limited resources and unique requirements. However, some of these techniques can be adapted and used with these constraint devices. In this paper, we propose security architecture for smart water management systems, the architecture leverages existing security solutions and design patterns
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paper_title: Real-time dynamic hydraulic model for potable water loss reduction

paper_content:

Abstract South Africa is a water scarce country with limited water resources and steadily growing water demand. Unacceptably high water losses and non-revenue water threaten our water resource security as well as the financial viability of municipal water service provision. Traditional approaches of solving water loss problems are not enough to make a significant improvement; for this, new approaches involving increased automation and monitoring are needed. Furthermore, the sensory and automation ICT-overlay required for the WDN can itself be a cause of technical problems that also need to be solved before water utilities will implement these techniques. This paper propose a real-time dynamic hydraulic model (DHM) based control system connected to near real-time sensing and actuation capability on the WDN as an effective approach to implementing an efficient, reliable and adaptive WDN. This is in contrast to current design and operation of most WDNs that rely on steady-state hydraulic models which have inherent limitations with respect to reliability and efficiency.
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paper_title: Prototype implementation of ambient RF energy harvesting wireless sensor networks

paper_content:

Energy harvesting is a key technique that can be used to overcome the barriers that prevent the real world deployment of wireless sensor networks (WSNs). In particular, solar energy harvesting has been commonly used to overcome this barrier. However, it should be noted that WSNs operating on solar power suffer form energy shortage during nighttimes. Therefore, to solve this problem, we exploit the use of TV broadcasts airwaves as energy sources to power wireless sensor nodes. We measured the output of a rectenna continuously for 7 days; from the results of this measurement, we showed that Radio Frequency (RF) energy can always be harvested. We developed an RF energy harvesting WSN prototype to show the effectiveness of RF energy harvesting for the usage of a WSN. We also proposed a duty cycle determination method for our system, and verified the validity of this method by implementing our system. This RF energy harvesting method is effective in a long period measurement application that do not require high power consumption.
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paper_title: A fault‐tolerant energy‐efficient clustering protocol of a wireless sensor network

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Energy efficiency in specific clustering protocols is highly desired in wireless sensor networks. Most existing clustering protocols periodically form clusters and statically assign cluster heads (CHs) and thus are not energy efficient. Every non-CH node of these protocols sends data to the CH in every time slot of a frame allocated to them using the time division multiple access scheme, which is an energy-consuming process. Moreover, these protocols do not provide any fault tolerance mechanism. Considering these limitations, we have proposed an efficient fault-tolerant and energy-efficient clustering protocol for a wireless sensor network. The performance of the proposed protocol was tested by means of a simulation and compared against the low energy adaptive clustering hierarchy and dynamic static clustering protocols. Simulation results showed that the fault-tolerant and energy-efficient clustering protocol has better performance than both the low energy adaptive clustering hierarchy and dynamic static clustering protocols in terms of energy efficiency and reliability. Copyright © 2012 John Wiley & Sons, Ltd.
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paper_title: Negative pressure wave based pipeline Leak Detection: Challenges and algorithms

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Negative pressure wave is a popular method to detect the occurrence and location of leak incidents in oil/gas pipeline. Three core technical challenges and related algorithm are discussed in this paper. The first is data quality. The balance between noise level and locating precision is discussed in filter design. The second one is dynamic slope in anomaly detection, whence a bi-SPC (Static Process Control) algorithms is proposed to make the threshold be adaptive. The third one is the false alarm caused normal working condition changes. Multiple-sensor paring algorithms is presented. With these algorithms, the robustness and locating precision of LDS (Leak Detection System) can be ensured.
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paper_title: ALWadHA Localization Algorithm: Yet More Energy Efficient

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Many wireless sensor networks (WSNs) applications, techniques, and algorithms require the position of the sensor nodes. Sensor nodes mainly rely on localization algorithms to determine their own physical location. Usually, these sensor nodes are equipped with a limited power source. Therefore, a localization algorithm used by a WSN should be an energy-aware algorithm. One of the energy efficient localization algorithms that has been proposed recently is an efficient localization algorithm for wireless ad hoc sensor networks with high accuracy (ALWadHA). In this paper, we investigate the impact of using three techniques by ALWadHA in improving the energy efficiency of ALWadHA: first, a single-estimation approach whereby a node estimates its position only once; second, dynamic power control whereby reference nodes reduce their transmission power based on their distance to the node that broadcasts the location request; and third an incremental and exponential requesting rate approach, which controls the frequency rate of sending the location request. Simulation results show that the final approach reduces the energy consumption of ALWadHA by 51.5%, without compromising the accuracy of the position estimation.
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paper_title: A Balanced Energy Consuming and Hole Alleviating Algorithm for Wireless Sensor Networks

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In wireless sensor networks, energy balancing and energy efficiency are the key requirements to prolong the network lifetime. In this paper, we investigate the problem of energy hole, in which sensor nodes located near the sink or in some other parts of the network die early due to unbalanced load distribution. Moreover, there is a dire need to utilize the energy resource efficiently. For this purpose, balanced energy consumption and hole alleviation, and energy-aware balanced energy-consuming and hole-alleviating algorithms are proposed. These algorithms balance the distribution of load along with efficient energy consumption. An optimal distance and energy-based transmission strategy with least expected error rate is adopted to forward the data packets of different sizes. Furthermore, the data distribution between high-energy consuming nodes and low-energy consuming nodes in each corona is analyzed. This distribution enables the proposed algorithms to outperform their counterparts in term of network lifetime, balanced energy consumption, and throughput on the cost of increased end-to-end delay.
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paper_title: Channel model and analysis for wireless underground sensor networks in soil medium

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Wireless underground sensor networks (WUSNs) constitute one of the promising application areas of the recently developed wireless sensor networking techniques. The main difference between WUSNs and the terrestrial wireless sensor networks is the communication medium. The propagation characteristics of electromagnetic (EM) waves in soil and the significant differences between propagation in air prevent a straightforward characterization of the underground wireless channel. To this end, in this paper, advanced channel models are derived to characterize the underground wireless channel and the foundational issues for efficient communication through soil are discussed. In particular, the underground communication channel is modeled considering not only the propagation of EM waves in soil, but also other effects such as multipath, soil composition, soil moisture, and burial depth. The propagation characteristics are investigated through simulation results of path loss between two underground sensors. Moreover, based on the proposed channel model, the resulting bit error rate is analyzed for different network and soil parameters. Furthermore, the effects of variations in soil moisture are investigated through field measurement results. The theoretical analysis and the simulation results prove the feasibility of wireless communication in underground environment and highlight several important aspects in this field. This work will lead to the provision of a generic framework for underground wireless communication and the realization of WUSNs.
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Title: Towards Achieving a Reliable Leakage Detection and Localization Algorithm for Application in Water Piping Networks: An Overview

Section 1: INTRODUCTION
Description 1: Introduce the importance of pipelines, the issue of leakages, factors causing pipe failures, and the significance of effective leakage detection methods.

Section 2: LEAKAGE DETECTION USING EXTERNALLY-BASED METHOD
Description 2: Discuss different externally-based methods for leakage detection, including acoustic emission, fiber optics sensing, gas injection, magnetic induction, and ground penetration radar methods. Compare their performance and limitations.

Section 3: LEAKAGE DETECTION USING INTERNALLY-BASED METHODS
Description 3: Explore internally-based methods such as balancing methods, pressure/flow monitoring, transient based methods, statistical methods, signal processing, and model-based detection methods. Compare their effectiveness and challenges.

Section 4: LEAK LOCALIZATION
Description 4: Describe techniques for localizing leakages, including traditional methods and recent advancements such as gradient intersection and wave propagation methods. Discuss their accuracy and practical applications.

Section 5: UTILIZATION OF WSN FOR LEAKAGE DETECTION
Description 5: Examine the role of wireless sensor networks (WSNs) in real-time leakage detection and pipeline health monitoring. Highlight challenges such as energy conservation, secure communication, and practical deployment strategies.

Section 6: CONCLUSIONS AND FUTURE WORKS
Description 6: Summarize the findings from the survey, highlighting the strengths and weaknesses of current leakage detection methods. Suggest areas for future research, particularly in detecting background type leakes and improving WSN deployment.