Leakage Localization In Virtual District Metered Areas With Differential Evolution

Leakages in water distribution systems (WDS) can lead to supply interruptions, contaminations and economic losses. Hence finding leaks before they cause severe problems is a crucial task for water utilities. To identify the existence of leaks, night flow measurements in district-metered areas (DMA) are common practice. Therefore, the entire system has to be subdivided in hydraulically separated partial networks. However, many utilities do not want to lose the hydraulic redundancy of their system and hence search for other solutions to identify and allocate leaks. In our research, the effects of leakages on the hydraulic behaviour of WDS are utilized to find the optimal solution for placing hydraulic sensors. From the discrepancy of the unperturbed and the perturbed WDS due to the occurrence of leakage, a methodology is developed which enables an efficient placement of flow meters and pressure sensors. This is achieved by a Fault Sensitivity Matrix (FSM). Finding the optimal position of a minimum number of sensors is carried out by a specific Genetic Algorithm called Differential Evolution (DE). DE is chosen due to its good rate of convergence reducing the computation time. This is of special interest for large WDS. Once an optimal sensor placement is obtained, DE is also used for leakage localization. The methodology has been applied and tested in two different WDS. The first WDS was a model network published by Poulakis in 2003. The second was a partial network of an Austrian city. Here the task was to place as few sensors as possible concerning economical costs while guaranteeing leakage localization in an area of a predefined size. In this paper it is shown that DE performs well, both on sensor placement and leakage localization, for both investigated systems. Additionally the implementation of demand and measurement uncertainties is outlined

Computational Efficient Small Signal Model For Fast Hydraulic Simulations

To increase the performance, quality and reliability of water distribution systems, implementing efficient computational and algorithmic techniques, has become a major tasks in hydraulic modelling. Examples can be found in online condition monitoring, real time control applications, or model based leakage detection and location approaches, etc. All these techniques require extensive hydraulic simulations. Well known and trusted hydraulic simulation tools like EPANET, etc. are deployed within the individual task specific code using provided interface routines. The flow dependent friction models of hydraulic systems require an iterative solution strategy to solve the problem. Although this is done efficiently using Newton-Raphson methods, the simulation output provided by those tools is limited to raw information (i.e. flow and head). Yet the superior algorithms often require more information than the raw output. I.e. gradient based optimization methods rely on derivative information. In this paper we report on a hydraulic small signal model which can be directly derived from the output of the hydraulic simulation tool itself. The model provides cheap computational access to internal information like gradients, sensitivity, etc. of the hydraulic simulation. The ATCA equilibrium structure of the model is numerically suitable and provides properties like a positive definite stiffness matrix enabling the efficient use of direct solvers like Cholesky decomposition. Further, the symmetry provides the property of self adjointness which enables the efficient use of Greens functions. We will present how the model can be assembled from the raw simulator output and present how to use it as linear approximation, for the computation of search directions in gradient based optimization schemes, for sensitivity analysis, as well as for the computation of covariance propagation due to uncertain demands

Benchmarking the scientific output of industrial wastewater research in Arab world by utilizing bibliometric techniques

Rapid population growth, worsening of the climate, and severity of freshwater scarcity are global challenges. In Arab world countries, where water resources are becoming increasingly scarce, the recycling of industrial wastewater could improve the efficiency of freshwater use. The benchmarking of scientific output of industrial wastewater research in the Arab world is an initiative that could support in shaping up and improving future research activities. This study assesses the scientific output of industrial wastewater research in the Arab world. A total of 2032 documents related to industrial wastewater were retrieved from 152 journals indexed in the Scopus databases; this represents 3.6 % of the global research output. The h-index of the retrieved documents was 70. The total number of citations, at the time of data analysis, was 34,296 with an average citation of 16.88 per document. Egypt, with a total publications of 655 (32.2 %), was ranked the first among the Arab countries followed by Saudi Arabia 300 (14.7 %) and Tunisia 297 (14.6 %). Egypt also had the highest h-index, assumed with Saudi Arabia, the first place in collaboration with other countries. Seven hundred fifteen (35.2 %) documents with 66 countries in Arab/non-Arab country collaborations were identified. Arab researchers collaborated mostly with researchers from France 239 (11.7 %), followed by the USA 127 (6.2 %). The top active journal was Desalination 126 (6.2 %), and the most productive institution was the National Research Center, Egypt 169 (8.3 %), followed by the King Abdul-Aziz University, Saudi Arabia 75 (3.7 %). Environmental Science was the most prevalent field of interest 930 (45.8 %). Despite the promising indicators, there is a need to close the gap in research between the Arab world and the other nations. Optimizing the investments and developing regional experiences are key factors to promote the scientific research

Assessing the Potential of LPWAN Communication Technologies for Near Real-Time Leak Detection in Water Distribution Systems

While low-power wide-area network (LPWAN) technologies have been studied extensively for a broad spectrum of smart city applications, their potential for water distribution system monitoring in high temporal resolution has not been studied in detail. However, due to their low power demand, these technologies offer new possibilities for operating pressure-monitoring devices for near real-time leak detection in water distribution systems (WDS). By combining long-distance wireless communication with low power consumption, LPWAN technologies promise long periods of maintenance-free device operation without having to rely on an external power source. This is of particular importance for pressure-based leak detection where optimal sensor positions are often located in the periphery of WDS without a suitable power source. To assess the potential of these technologies for replacing widely-used wireless communication technologies for leak detection, GPRS is compared with the LPWAN standards Narrowband IoT, long-range wide area network (LoRaWAN) and Sigfox. Based on sampling and transmission rates commonly applied in leak detection, the ability of these three technologies to replace GPRS is analyzed based on a self-developed low-power pressure-monitoring device and a simplified, linear energy-consumption model. The results indicate that even though some of the analyzed LPWAN technologies may suffer from contractual and technical limitations, all of them offer viable alternatives, meeting the requirements of leak detection in WDS. In accordance with existing research on data transmission with these technologies, the findings of this work show that even while retaining a compact design, which entails a limited battery capacity, pressure-monitoring devices can exceed runtimes of 5 years, as required for installation at water meters in Austria. Thus, LPWAN technologies have the potential to advance the wide application of near real-time, pressure-based leak detection in WDS, while simultaneously reducing the cost of device operation significantly

Serious Sensor Placement—Optimal Sensor Placement as a Serious Game

In this paper, we present a novel approach in water loss research combining two different topics: The optimal placement of pressure sensors to localize leaks in water distribution systems and Serious Gaming—games that are not only entertaining but that are also serving another purpose. The goal was to create a web interface, through which gamers could place sensors in a water distribution system model, in order to improve these sensor positions after they had been evaluated by a suitable algorithm. Two game objectives are to be pursued by the players: reaching a specified net coverage while not using more than a maximum number of sensors. For this purpose, an existing optimal sensor placement algorithm was extended and implemented, together with two hydraulic models taken from literature. The resulting Serious Game was then tested and rated in a case study. The results showed that human players are able to reach solutions that are similar regarding net coverage to those obtained by optimization, within in a short amount of time. Furthermore, it was shown that the implementation of the ideal sensor placement problem as a Serious Game motivates the players to get better and better results, while also providing them with an enjoyable gaming experience

Sensor Placement and Leakage Localization considering Demand Uncertainties

AbstractDetecting and locating leaks in water distribution systems is of great interest. For the localization of leaks we make use of pressure sensors alongside a calibrated hydraulic EPANET model of the investigated system. Leakage localization is solved with a Differential Evolution algorithm. For sensor placement we use a non-binarized leak sensitivity matrix with a projection-based leak isolation approach. Additionally, the effect of uncertain hydraulic model parameters on the measurement quantities is investigated by Monte Carlo simulations and was incorporated in the sensor placement algorithm. Uncertainty analysis, sensor placement and leakage location was tested on two hydraulic systems