Optimal Design of District Metering Areas

Abstract The search for optimal segmentations aimed at defining district metering areas (DMAs) is a challenging and crucial issue in the analysis, planning and management of water distribution networks (WDNs). The need to select optimal segmentations relates to a number of important technical reasons. Today, the most relevant one is the leakage management by means of pressure-control zones. This contribution proposes a novel two-steps strategy for DMAs planning. The strategy is based on the segmentation design as first step, to achieve a scenario of optimal locations of "conceptual cuts"; during the second step, these are the candidate for the location of (closed) gate valves or flow measurement devices that gave rise to district monitoring areas (DMAs). The segmentation step is performed solving a multi-objective optimization problem (i.e. WDN-oriented modularity maximization versus the number of "conceptual cuts" minimization). The second step accomplishes the real DMAs design by solving a three-objective optimization, i.e. the minimization of the background leakages versus the unsupplied customers demand versus the flow observations. This means that the procedure will search for a set of scenarios having a number of closed gate valves installed at the "conceptual cuts" that do not decrease the WDN hydraulic capacity below that necessary for a sufficient service to customers, while contemporarily reducing the background leakages. A pressure-driven modelling approach is used to predict background leakage reduction and the unsupplied customers demand. The procedure is explained on a benchmark network from literature, the Apulian network

Towards serious gaming for water distribution networks sizing: a teaching experiment

Abstract Real-life engineering problems relate to different technical aspects to be considered at the same time. Traditional teaching techniques for engineering students (i.e., future decision-makers for such problems) sometimes need to be supplemented to convey this complexity, and thus innovative approaches are needed. A new and useful approach allowing a more intuitive understanding of real-life problems is serious gaming (SG), which combines a game environment and utility functions to address real problems. This paper describes a first attempt to use SG to help engineering students learn and deal with the complexities of designing water distribution networks given multiple objectives and uncertainty. This application of SG relates to five benchmark water distribution networks, and students were asked to find the optimal value of pipe diameters to minimize the capital cost of pipes. The results of the experiment show that students learn in less time how to design water distribution networks while enjoying the experience. Most students found the approach useful, claiming that the difficulty in approaching the pipe sizing problem decreased considerably as the practice of the game increases. The results of the experiment suggest that SG may have value in learning how to design other engineering systems

Sewer networks monitoring through a topological backtracking

The interest in wastewater monitoring is always growing, with applications mainly aimed at detection of pollutants and at the environmental epidemiological surveillance. However, it often happens that the strategies proposed to manage these problems are inapplicable due to the lack of information on the hydraulics of the systems. To overcome this problem, the present paper develops and proposes a topological backtracking strategy for the optimal monitoring of sewer networks, which acts by subrogating the hydraulic information with the geometric ones, e.g., diameter and slope, thus not requiring any hydraulic simulation. The topological backtracking approach aims at evaluating an impact coefficient for each node of the network used to face with the problems of sensor location and network coverage for purposes related to the spread of contaminants and pathogens. Finally, the positioning of the sensors for each monitoring scheme is addressed by a priority rank, based on the efficiency of each sensor in terms of network coverage with respect to a specific weight (e.g., length, flow). The main goal is to design a monitoring scheme that provide the required coverage of the network by minimizing the number of sensors with respect to specific measurement threshold value. The results show the effectiveness of the strategy in supporting the optimal design with the topological-based backtracking approach without the necessity of performing hydraulic simulations, with great advantage in terms of required data and computational time

Active Leakage Control with WDNetXL

Abstract Water losses in Water Distribution Networks (WDNs) are classified in background and burst outflows. Bursts are generally the natural evolution of background leakages, driven by external factors that entail major water outflows, generating changes of WDN hydraulic functioning, detectable as anomalies in monitored flow/pressure data. Active leakage control strategies aim at prompt detection, localization and repair of pipe burst, thus reducing possible damages to private/public properties, minimize unplanned works, and reduce volume of lost water. This contribution presents the novel Leakage Control module of the WDNetXL system, aimed at supporting various active leakage control actions ranging from the design of effective pressure sampling system up to prioritizing of possible failed pipes to survey

Orientation-Dependent Electronic Structures and Charge Transport Mechanisms in Ultrathin Polymeric n-Channel Field-Effect Transistors

We investigated the role of metal/organic semiconductor interface morphology on the charge transport mechanisms and energy level alignment of the n-channel semiconductor poly{[N,N'-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)} (P-(NDI2ODT2)). Variable-temperature study of well-ordered edge-on-oriented P(NDI2OD-T2) monolayer and multilayer field-effect transistors fabricated via Langmuir-Schafer (LS) method reveals a higher activation energy for the edge-on morphology when compared to that extracted for the face-on oriented P(NDI2OD-T2) spin-coated films, which showed a weaker temperature dependence. Near-ultraviolet inverse photoemission and low-energy electron transmission spectroscopies are utilized to study these rnicrostructurally defined polymeric films. The cross correlations of these techniques with the device characterization reveals the role of the molecular orientation at the semiconductor/contact interface in shifting the charge injection barrier. Finally, we demonstrate that the injection barrier for electrons is higher for the LS/edge-on than in the spin-coated/face-on films

Activation of α7 nicotinic acetylcholine receptor by nicotine selectively up-regulates cyclooxygenase-2 and prostaglandin E(2 )in rat microglial cultures

BACKGROUND: Nicotinic acetylcholine (Ach) receptors are ligand-gated pentameric ion channels whose main function is to transmit signals for the neurotransmitter Ach in peripheral and central nervous system. However, the α7 nicotinic receptor has been recently found in several non-neuronal cells and described as an important regulator of cellular function. Nicotine and ACh have been recently reported to inhibit tumor necrosis factor-α (TNF-α) production in human macrophages as well as in mouse microglial cultures. In the present study, we investigated whether the stimulation of α7 nicotinic receptor by the specific agonist nicotine could affect the functional state of activated microglia by promoting and/or inhibiting the release of other important pro-inflammatory and lipid mediator such as prostaglandin E(2). METHODS: Expression of α7 nicotinic receptor in rat microglial cell was examined by RT-PCR, immunofluorescence staining and Western blot. The functional effects of α7 receptor activation were analyzed in resting or lipopolysaccharide (LPS) stimulated microglial cells pre-treated with nicotine. Culture media were assayed for the levels of tumor necrosis factor, interleukin-1β, nitric oxide, interleukin-10 and prostaglandin E(2). Total RNA was assayed by RT-PCR for the expression of COX-2 mRNA. RESULTS: Rat microglial cells express α7 nicotinic receptor, and its activation by nicotine dose-dependently reduces the LPS-induced release of TNF-α, but has little or no effect on nitric oxide, interleukin-10 and interleukin-1β. By contrast, nicotine enhances the expression of cyclooxygenase-2 and the synthesis of one of its major products, prostaglandin E(2). CONCLUSIONS: Since prostaglandin E(2 )modulates several macrophage and lymphocyte functions, which are instrumental for inflammatory resolution, our study further supports the existence of a brain cholinergic anti-inflammatory pathway mediated by α7 nicotinic receptor that could be potentially exploited for novel treatments of several neuropathologies in which local inflammation, sustained by activated microglia, plays a crucial role

Monitoring planning for urban drainage networks

Urban drainage network (UDN) monitoring is an important task whose planning can be related to various purposes, as for example contaminant detection and epidemiological studies. This paper proposes two different strategies for the identification of a monitoring system for UDNs. The optimal solution, in terms of location and number of sensors, is firstly addressed using a deterministic approach. A new mathematical model is developed and a global optimization solver is employed to perform the optimization procedure. Secondly, the position of devices is also investigated using a new strategy based on the complex network theory (CNT) tools. The comparison between the results achieved by both the strategies is finally presented with reference to a benchmark network

Relevance of hydraulic modelling in planning and operating real-time pressure control: case of oppegård municipality

Abstract Technical best practices recommend pressure control as an effective countermeasure to reduce leakages in water distribution networks (WDNs). Information and communication technologies allow driving pressure reducing valves (PRVs) in real-time based on pressure observed at remote control nodes (remote real-time control – RRTC), going beyond the limitations of classic PRV control (i.e. with target pressure node just downstream of the device). Nowadays, advanced hydraulic models are able to simulate both RRTC-PRVs and classic PRVs accounting for unreported and background leakages as diffused pressure-dependent outflows along pipes. This paper studies how such models are relevant to support pressure control strategies at both planning and operation stages on the real WDN of Oppegård (Norway). The advanced hydraulic model permits demonstration that RRTC-PRVs in place of existing classic PRVs might reduce unreported and background leakages by up to 40%. The same analysis unveils that advanced models provide reliable evaluation of leakage reduction efforts, overcoming the inconsistencies of lumped indexes like the Infrastructure Leakage Index (ILI). Thereafter, the model allows comparison of three strategies for the real-time electric regulation of PRVs in some of the planned scenarios, thus supporting real-time operation of RRTC-PRVs