The LEAKAGE is one of the most important issues in WATER Distribution Systems (WDS) which imposes huge costs to WATER industries. Current methods detecting LEAKAGEs are costly, time consuming, and labor intensive. New methods have recently been considered based on calibrating nodal pressures. Modeling and calibrating the nodal pressure using genetic algorithm is one of these methods which unfortunately is not yet accurate enough to be applied widely on real networks and more investigations is needed in this regard. In this paper, a new approach is developed which detects and eliminate the nodes with no LEAKAGE among unknown demand nodes step-by-step. In this method, an ordinary calibration was accomplished. Some nodes with no LEAKAGEs are then eliminated from the set of leaky nodes and the network was calibrated again. Several iteration of this process have shown a good improvement in the LEAKAGE DETECTION in WDS.

WATER distribution networks are of the most important urban infrastructure for WATER supply. Given that WATER loss is currently a global concern, and WATER demand s increasing,this has made it necessary to manage demand and improve consumption patterns. One of the most important ways to manage consumption is to reduce unaccounted-for WATER. LEAKAGE is one of the components of unaccounted-for WATER in the WATER supply networks. Also, due to population growth and WATER crisis in a large part of the world, the issue of LEAKAGE in urban WATER supply networks has become very important. LEAKAGE in WATER distribution networks wastes energy and WATER resources, increasing damage to infrastructure, and contaminating drinking WATER. WATER LEAKAGE in the WATER distribution systems (WDSs) varies between 5 to 55% of the total WATER. Therefore, LEAKAGE has an important effect on system performance. The importance of LEAKAGE can be found in issues such as WATER scarcity, optimal use of available resources and high costs of WATER treatment and distribution. In other words, in the discussion of WATER transmission and use, we are observing obvious and hidden waste, which is important in dry and semi-arid countries like Iran, so this need to minimize the amount of waste so that resources can be used optimally. In recent years, various solutions have been considered to reduce LEAKAGE by researchers and managers of the WATER industry,this includes hardware methods (acoustic procedures, flow measurements, etc. ) and software methods (neural network, genetic algorithm, EPANET, WATERGEMS, etc. ). In this paper, a software method is developed to facilitate LEAKAGE DETECTION and eliminate uncertainty of hardware methods such as human and device errors. In other words, to reduce the cost and time of hardware methods, a simulation-modeling method is developed here based on harmonic search algorithm. For this purpose, EPANET hydraulic model and MATLAB environment have been used. Different scenarios for locating leaks and finding LEAKAGE sizes were investigated in two WATER supply networks. Scenarios include one leak and three simultaneous leaks in different parts of the networks. Also, the variability of nodal demands during the day and night was considered as an uncertainty parameter, and thus the coefficients of the consumption pattern during 24 hours were allocated to the nodes of both networks in EPANET software. After that, the main body of the Harmony Search Algorithm was written in MATLAB environment, and in accordance with each of the location and LEAKAGE scenarios, the Harmony Search Algorithm was developed. Algorithm parameters were also adjusted according to the type of scenario, the size of the studied network (number of nodes) and the number of variables to produce acceptable responses. The algorithm in MATLAB environment was linked to EPANET software. The developed model examined 14 different scenarios. The results show that the developed model has been successful in locating one leak, finding the size of the leak, and locating three leaks, respectively. In general, the model has had an acceptable performance in locating and finding the size of LEAKAGE during the day and night.

WATER loss has been changed into a global concern in recent decades [1]. Since WATER demand has been increased, it is necessary to manage its consumption patterns to overcome this problem. The most important part of managing WATER consumption, is to decrease the WATER loss. In this paper a new idea has been presented to detect the LEAKAGE location and its quantity in a WATER distribution network, using nodal pressures analyzes in two cases of with and without LEAKAGE discharges. The results have shown that this method not only can determine the location of leaky node, but also the LEAKAGE quantity, by using nodal pressure data.

Iran has limited WATER resources that require preservation and reducing WATER loss from reservoirs, especially in arid and semi arid regions. There are a number of methods available for to control WATER loss from reservoirs and canals. Concrete linings in WATER reservoirs and ponds are durable, but their efficiency is limited. Geomembrane sheets are another method of controlling LEAKAGE from WATER reservoirs. In this research, high density polyethylene was used to lining a concrete WATER reservoir to test its suitability for WATER proofing and chemical resistance. The benefits and drawbacks of this new lining material were investigated in the design, execution and operation stages. Subsequently, the effectiveness of this liner to control WATER loss was tested under different. The results showed that a geomembrane liner over a concrete lining requires special consideration during design, installation and maintenance and accessories such as pipes and sumps to reduce excessive stress on the liner. The analysis of WATER LEAKAGE from the liner showed that proper design and installation of the liner and accessories reduce WATER loss about 38% and limit LEAKAGE to 16.9 mm/day/m2.

Nowadays WATER loss has been turned into a global concern and on the other hand the demand for WATER is increasing. This problem has made the demand management and consumption pattern reform necessary. One of the most important methods for managing WATER consumption is to decrease the WATER loss. In this study by using neural networks, a new method is presented to specify the location and quantity of LEAKAGEs in WATER distribution networks. In this method, by producing the training data and applying it to neural network, the network is able to determine approximate location and quantity of nodal LEAKAGE with receiving the nodal pressure. Production of training data is carried out by applying assumed LEAKAGE to specific nodes in the network and calculating the new nodal pressures. The results show that by minimum use of hydraulic data taken from pressures, not only this method can determine the location of nodal LEAKAGEs, but also it can specify the amount of LEAKAGE on each node with reasonable accuracy.

AbstractIntroduction: Conventional leak DETECTION methods are costly and time-consuming, so attention has recently been drawn to methods that detect LEAKAGE by network modeling comprehensively.Methods: In these methods, the difference between the measured pressure and flow rate and those obtained by the model is minimized as a fitness function by calibrating the network and adjusting the nodal demands. It has been established by analysis that the fitness function in itself cannot be a good guide to achieving the minimum point. This drawback was solved by using the ACO method. In addition to the fitness, this method employs a parameter called heuristic guidance to improve its capabilities.Results: This research compared three ACO-based optimization methods. The first was ACO with fixed heuristic guidance already introduced in the literature. In the second method, the heuristic guidance varies by the values of the observed pressures and pressure decline versus the no-leak state. The third is studied and compared by integrating SSEM and ACO models. These methods were investigated on a network derived from the literature and the Birjand network.Conclusion: The results revealed that the methods proposed here achieved more precise results in a shorter time and with fewer iterations.

One of the most important requirements for gas and fluid industrial pipelines is the on-line LEAKAGE DETECTION and investigation. In this paper, DETECTION of leak and determination of its amount using radioactive tracer injection method has been simulated by Monte Carlo MCNP code. The detector array included two NaI (Tl) detectors which were located before and after the considered position, measures emitted gamma from radioactive tracer. After calibration of radiation detectors, the amount of LEAKAGE can be calculated based on the count difference of areas under the radiation detectors. Also, the factors affecting the detectable amount of LEAKAGE such as the material, thickness, diameter of pipe, types of fluid, radiation detector crystal dimension, the activity of tracer and its type (24Na, 82Br, 131I, 99mTc, 113mIn) have been investigated. According to the results, for example, LEAKAGE more than 0. 007% in volume of the inlet fluid for iron pipe with outer diameter 4 inch and thickness of 0. 5 cm, petrol as fluid inside pipe, 3 3 inch detector and 24Na with activity of 100 mCi as detector can be detected by the presented method.

One of the main responsibilities of WATER and wasteWATER companies in the field of operating of WATER distribution networks (WDNs) is the management and control of LEAKAGE from these networks. In this regard, active LEAKAGE control is one of the main strategies in reducing LEAKAGE and achieving economic level of LEAKAGE (ELL). In this paper, a practical methodology was developed to determine the economic level of LEAKAGE which is included the steps determining the points of pressure and flow rate measurements, collecting of required field data and cost data, the estimation of LEAKAGE level in the network and the determination of the economic level of LEAKAGE of the network based on the active LEAKAGE control strategy. Economic performance indicators such as the economic LEAKAGE index (ELI) and the economic network efficiency (ENE) are also obtained using the determined ELL. The developed methodology was applied for a district of the WDN of Mashhad. The results showed that the economic level of LEAKAGE in the study area is 27. 5 m3/connection/year. While the current level of LEAKAGE was estimated to be around 49. 2 m3/connection/year, based on the minimum night flow (MNF) analysis. Moreover, the ELI and ENE were calculated 1. 79 and 56% respectively. The developed methodology in this paper can assist practitioners and managers of WATER and wasteWATER companies for target-setting of the level of LEAKAGE and determining of the ELL based on it.

Background: Anastomotic LEAKAGE (AL) is the main complication of colorectal surgeries. Recent studies haveassessed the effects of the ghost ileostomy on preventing complications related to a defunctioning stoma (DS)in high-risk anastomoses. In this study, we aimed to review patients who underwent ghost ileostomy and assesstheir colon LEAKAGE score (CLS) and Dutch LEAKAGE score (DULK) to evaluate their preoperative AL risk andpost-operative AL diagnostic score, respectively. We examined whether the suggested cut-off points of thesescores (>11 for CLS and >4 for DULK) could be appropriate criteria for determining when to insert ghostileostomy and when to convert it to a DS.Methods: All patients from three referral hospitals in Shiraz, Iran who underwent colorectal surgery withghost ileostomy during 2019-2020 were enrolled in this retrospective case series. We calculated preoperativeCLS and post-operative DULK scores for all patients and assessed what diagnostic and therapeutic measureswere performed for them based on their scores.Results: AL was diagnosed in two of 34 patients. Eight patients had a total CLS score of 11 and above, butonly one of them experienced AL. The other case of AL had a CLS score of 10. The DULK score of these twopatients increased during hospitalization.Conclusion: Because of the importance of accurately identifying high-risk patients for ghost ileostomy, itis imperative to undertake additional research aimed at determining the optimal cut-off value for CLS ordevising alternative valid scoring systems. DULK score could be an appropriate post-operative monitoring toolto reduce morbidity.