David Ayala-Cabrera

GPR-based water leak models in water distribution systems

This paper addresses the problem of leakage in water distribution systems through the use of ground penetrating radar (GPR) as a nondestructive method. Laboratory tests are performed to extract features of water leakage from the obtained GPR images. Moreover, a test in a real-world urban system under real conditions is performed. Feature extraction is performed by interpreting GPR images with the support of a pre-processing methodology based on an appropriate combination of statistical methods and multi-agent systems. The results of these tests are presented, interpreted, analyzed and discussed in this paper.

WATER SUPPLY CLUSTERS BY MULTI-AGENT BASED APPROACH

The rational distribution of water in a water supply network (WSN) is a complex problem, especially for systems of large scale. Its complexity is continually increasing from the point of view of technical management. This represents a really important problem for water companies around the world that witness how the mathematical models of their networks are not accurate anymore and their engineering tools become obsolete. As a consequence, they do not have a clear vision of the balance between production and distribution, that is to say, between supply and demand. As a result, many companies worldwide, especially those managing big cities networks, are interested in new methods to improve the control and management of their networks, essentially to control leaks and to improve water quality. One of the methods that attracts great interest is division into DMA (district metered areas). The division of WSN into DMA is a partition of the supply network into subsystems with controlled inputs and outputs, building smaller independent networks. Due to the complexity of the problem, efficient techniques are required. In this contribution we use a multi-agent based approach that takes advantage of the distributed nature of water distribution systems. This methodology offers an adequate solution to DMAs paradigm through clusters that allows the conditions for these clusters to become small water supply networks.

Water supply system component evaluation from GPR radargrams using a multi-agent approach ☆

Abstract This paper uses a multi-agent approach as a quick and easy tool for the interpretation and analysis of the characteristics of Water Supply System (WSS) components when working on a collection of Ground Penetrating Radar (GPR) survey files. The multi-agent algorithm proposed in this paper has been developed in Matlab and is based on Game Theory. The input is the result of the GPR radargram survey and the output consists of the agent scores in the game proposed in this paper. Useful information can be gained by interpreting the columns of the output matrix that describe the agents’ movements, together with the associated racing times. In effect, this analysis enables a simple determination of the electromagnetic properties of the underground system and provides an accurate classification of these properties. The results of this agent racing algorithm are promising, since it groups, and consequently, decreases the number of points that make up the initial radargrams; while at the same time preserving its main properties, and enabling clearer views of pipes and a better identification of the components in WSS.

Towards the visualization of water supply system components with GPR images

We propose a methodological tool for examining the layout and revealing the concealed characteristics of urban water supply systems (WSS). For this purpose, we use underground images obtained with ground penetrating radar (GPR) as a method that does not alter the system conditions and environmental characteristics (non-destructive methods). The study focuses on wave amplitude and uses intensive matrix manipulation. We obtain promising results as the methodology, which is non-subjective and repeatable, visualizes buried pipes with efficiency. This tool will help WSS managers obtain a more accurate picture of WSS and so offer a better service to users.

GPR data analysis using multi-agent and clustering approaches: A tool for technical management of water supply systems

In this paper a combination of the multi-agent paradigm and a very well known clustering technique is used for unsupervised classification of subsoil characteristics working on a collection of ground penetrating radar (GPR) survey files. The main objective is to assess the feasibility of extracting features and patterns from radargrams. By optimizing both the field work and the interpretation of the raw images our target is to obtain visualizations that are automatic, fast, and reliable so to suitably assess the characteristics of the prospected areas and extract relevant information. The architecture of the system may be split into three interrelated processes: (a) pre-processing, (b) hierarchical agglomerative clustering, and (c) retrieval and visualization. The proposed system shows the viability of arranging GPR data from survey files into clusters, thus reducing the amount of information to be dealt with, while preserving its reliability. The system also helps characterize subsoil properties in a very natural and fast way, favors GPR files interpretation by non-highly qualified personnel, and does not require any assumptions about subsoil parameters. A powerful tool to analyze underground components in water supply systems is thus generated that acts in a non-destructive way and supports decision-making in water supply management.

Multi-Agent Simulation of Hydraulic Transient Equations in Pressurized Systems

AbstractComputational modeling pervades virtually every industrial process. By using numerical representations of the behavior of elements that constitute a system it is possible to obtain efficient and safe designs. Moreover, system operation can be better defined by using such models, thus enabling greater reliability and control. In this paper the use of agents to solve the equations describing fast transients in water networks is investigated. As the simulation of hydraulic transients in pressurized systems is a naturally distributed problem, the authors argue that a multi-agent based system is very suitable for the solution of this complex engineering phenomenon. A hybrid solution is built by deploying agents to work with sets of equations describing hydraulic transient behavior in pipeline systems. The details necessary to assemble a complete and lubricated machine to model the complex phenomenon of hydraulic transients in pressurized systems are described. This research develops a platform that con...

Analysis of gpr data through interpretation of pre-processed images obtained by a multi-agent approach to identify pipes in water supply systems

This work focuses on the development of easy application procedures for visualizing the characteristics of the components of water supply systems (WSS), quickly and by non highly qualified staff. We study databases related to the underground obtained with GPR (ground penetrating radar). In this study we perform GPR imaging of pipes of four different materials commonly used in WSSs buried in dry soil. The data obtained from the survey are pre-processed with a multi-agent method consisting in a race of agents. Subsequently, analysis and interpretation of the results, seeking to generate forms that allow a quick understanding, are performed. These forms are analyzed in order to assess the feasibility of pattern recognition revealing existence of pipes. The results are promising in the attempt of generating suitable databases and parameters to train intelligent systems for characterizing components of WSS.

Error Analysis of Some Demand Simplifications in Hydraulic Models of Water Supply Networks

Mathematical modeling of water distribution networks makes use of simplifications aimed to optimize the development and use of the mathematical models involved. Simplified models are used systematically by water utilities, frequently with no awareness of the implications of the assumptions used. Some simplifications are derived from the various levels of granularity at which a network can be considered. This is the case of some demand simplifications, specifically, when consumptions associated with a line are equally allocated to the ends of the line. In this paper, we present examples of situations where this kind of simplification produces models that are very unrealistic. We also identify the main variables responsible for the errors. By performing some error analysis, we assess to what extent such a simplification is valid. Using this information, guidelines are provided that enable the user to establish if a given simplification is acceptable or, on the contrary, supplies information that differs substantially from reality. We also develop easy to implement formulae that enable the allocation of inner line demand to the line ends with minimal error; finally, we assess the errors associated with the simplification and locate the points of a line where maximum discrepancies occur.