Average Leakage Rate Research Articles

Research on the Dynamic Leaking and Diffusion Law of Hydrogen-Blended Natural Gas under the Soil–Atmosphere Coupled Model

With the breakthrough in mixing hydrogen into natural gas pipelines for urban use, the widespread application of hydrogen-blended natural gas (HBNG) in energy delivery is imminent. However, this development also introduces significant safety concerns due to notable disparities in the physical and chemical properties between methane and hydrogen, heightening the risks associated with gas leaks. Current models that simulate the diffusion of leaked HBNG from buried pipelines into the atmosphere often employ fixed average leakage rates, which do not accurately represent the dynamic nature of gas leakage and diffusion. This study uses computational fluid dynamics (CFD) 2024R1 software to build a three-dimensional simulation model under a soil–atmosphere coupling model for HBNG leakage and diffusion. The findings reveal that, in the soil–atmosphere coupling model, the gas diffusion range under a fixed leakage rate is smaller than that under a dynamic leakage rate. Under the same influencing factors in calm wind conditions, the gas primarily diffuses in the vertical direction, whereas under the same influencing factors in windy conditions, the gas mainly diffuses in the horizontal direction.

Estimating leakage rates for Ontario forest offset projects

Forest offset projects can contribute to climate change mitigation. The key question is whether mitigation benefits of forest offset projects are undermined by shifting emissions elsewhere—a problem known as leakage. In this study, we estimated leakage caused by market effects for forest offset projects in Ontario, Canada, using a well-known method developed by Murray et al. (2004). Leakage was calculated using price elasticities of supply and demand from a literature search of studies relevant to Ontario. The average leakage rate was 52.2%, with the 5–95th percentile range from 24.7% to 76.2%. Leakage estimates were tested for sensitivity to policy scale and substitutability parameters.

Ni–Co spinel based oxide as new type of additive to glass seal for solid oxide fuel cells

Glass seals utilized in Solid Oxide Fuel Cells (SOFCs) can be subject to modification through the incorporation of oxide additives to bolster their mechanical strength. This research focuses on a novel class of additives, specifically protective coating materials designed for alloy interconnects. It is crucial to emphasize that the glass seal interfaces directly with the protective coating, bypassing direct contact with the alloy itself. The efficacy of this approach is exemplified through the utilization of Ni–Co spinel-based oxide, established as an effective protective substance for stainless steel interconnects. The introduction of a minute quantity of Ni–Co oxides does not induce alterations in the glass seal properties, encompassing phase structure, microstructure, thermal expansion coefficient (CTE), and softening behavior. The Ni–Co oxide additive serves to mitigate the glass devitrification tendency, leading to a substantial augmentation in shear strength at the seal-interconnect interface and a marked enhancement in sealing properties. The composite seal, enriched with 3.0 wt% Ni–Co oxide, showcases superior sealing performance, demonstrating exceptional stability throughout a rigorous 1200-h test. The average leakage rate during this test period stands at 0.0024 sccm⋅cm−1. The incorporation of Ni–Co oxide triggers the formation of needle-shaped crystals, playing a pivotal role in averting channel void formation and augmenting the bonding strength between the seal and interconnect. Consequently, this fortifies gas tightness, ensuring the maintenance of outstanding sealing performance over an extended duration.

An In-Vitro Comparison of Steady State Leakage Rates through Introducer Sheaths Used for Fenestrated Endovascular Aortic Aneurysm Repair

Objectives– fEVAR involves deploying a covered stent into the aorta followed by multiple visceral stents through fenestrations in the main body of graft. The most commonly used large sheaths for cannulation of visceral vessels are the Gore DrySeal Flex, Cook Performer Check-Flo and Medtronic Sentrant. None of these sheaths were designed for the insertion of multiple sheaths, and so a slow but steady leakage of blood occurs during the procedure. The aim of this paper is to assess in an in vitro setting which large bore sheath has the best valve for use when multiple smaller sheaths are inserted through it. MethodsThree large bore introducer sheaths (LBIS) were used for this study, The Gore DrySeal Flex LBIS, Medtronic Sentrant LBIS and Cook Performer Check-Flo LBIS. A test rig was constructed, made of an 18-litre fluid reservoir mounted vertically and receiving a constant supply of water from a domestic water supply which flowed into the reservoir and out of an overflow. The reservoir was connected to the LBIS by a vertical plastic pipe with an internal diameter of 40mm and an isolation valve. The LBIS was connected to the isolation valve by inserting the LBIS up a flexible silicone tube connected to the isolation valve. The LBIS was subject to a constant column/pressure of water and fluid leakage from the LBIS was collected in a plastic pot/tray placed underneath the LBIS. The leakage rates through each LBIS were determined for the following smaller diameter sheath combinations inserted through the valve, one 6 French Sheath, two 6 French Sheaths, two 6 French Sheaths and one 7 French Sheath. This was done to closely mimic a fEVAR procedure in vitro. The procedure was to insert different sheath combinations through the non-return valves in the LBIS and measure the volume of fluid that leaked through the valves. The leaked fluid was weighed, and the weight was converted to volume using the density of water (1g/ml). ResultsThe average (mean) leakage rates for each LBIS and each sheath combination showed that leakage rates when only one sheath was inserted were very low. For all three LBIS’s tested, the leakage rates increased dramatically when multiple sheaths were inserted. The Medtronic LBIS leaked the most, followed by Cook, followed by Gore. For the Cook LBIS, the leakage rates exhibited with 2 x 6 French sheaths were approx. 106 times greater than those for the Gore LBIS and five times greater for the 2 x 6 French + 1 x 7 French sheath combination. A similar comparison for the Medtronic LBIS vs the Gore LBIS yields factors of 132 and 8. ConclusionsLeakage rates increase significantly when multiple sheaths are inserted and the Gore LBIS demonstrates significantly lower leakage than both the Cook and Medtronic during procedures that require simultaneous, multiple insertions of smaller sheaths. Although the Gore Dryseal has by far the lowest leakage rate when three small diameter sheaths are inserted (just under 1ml/s), depending on the duration of the procedure this could still result in significant blood loss.

Research on thermal deformation of cylinder bore with orthogonal experiment method of aluminum alloy cylinder block in diesel engine

Using aluminum alloy materials provides an efficient and direct method for achieving engine weight reduction. In this study, a thermo-mechanical coupling simulation model of the diesel engine was established to investigate the deformation of cylinder bores in both cast iron and aluminum alloy cylinder blocks. The reliability of the simulation model is validated by the temperature field test of the cast iron cylinder. Four evaluation indexes, namely average roundness, cylindricity, coaxiality, and light leakage, were used to assess the deformation of the cylinder bore. The results indicate that the temperature is the primary factor contributing to the deformation in both cast iron and aluminum alloy cylinder bores. Under thermo-assembly condition, the average roundness, cylindricity, coaxiality, and light leakage rate of aluminum alloy cylinder bore were observed to be higher by 36.71 %, 12.69 %, 14.77 %, and 18.85 %, respectively, compared to those of cast iron cylinder bore. To decrease the deformation of the cylinder bore, the orthogonal experiment method was used to study the three factors affecting the heat dissipation of the water jacket. It was discovered that extending the water jacket extends upward was the most effective way to reduce the temperature of the cylinder block. By selecting the optimal combination scheme for simulation calculations, an optimized cylinder temperature of 162 °C, with the maximum deformation of the cylinder bore decreasing by 13.64 %. Additionally, the average roundness, cylindricity, coaxiality, and light leakage rate of the cylinder bore showed reductions of 17.48 %, 21.8 %, 23.00 %, and 14.10 %, respectively, when compared to the original aluminum alloy cylinder block.

A Novel Vascular Anastomotic Coupling Device for End-to-End Anastomosis of Arteries and Veins.

Hand-sutured (HS) techniques remain the gold standard for most microvascular anastomoses in microsurgery. HS techniques can result in endothelial lacerations and back wall suturing, leading to complications such as thrombosis and free tissue loss. A novel force-interference-fit vascular coupling device (FIF-VCD) system can potentially reduce the need for HS and improve end-to-end anastomosis. This study aims to describe the development and testing of a novel FIF-VCD system for 1.5 to 4.0 mm outside diameter arteries and veins. Benchtop anastomoses were performed using porcine cadaver arteries and veins. Decoupling force and anastomotic leakage were tested under simulated worst-case intravital physiological conditions. The 1.5 mm FIF-VCD system was used to perform cadaver rat abdominal aorta anastomoses. Benchtop testing showed that the vessels coupled with the FIF-VCD system could withstand simulated worst-case intravital physiological conditions with a 95% confidence interval for the average decoupling force safety factor of 8.2 ± 1.0 (5.2 ± 1.0 N) and a 95% confidence interval for the average leakage rate safety factor of 26 ± 3.6 (8.4 ± 0.14 and 95 ± 1.4 μL/s at 150 and 360 mmHg, respectively) when compared to HS anastomotic leakage rates (310 ± 14 and 2,100 ± 72 μL/s at 150 and 360 mmHg, respectively). The FIF-VCD system was successful in performing cadaver rat abdominal aorta anastomoses. The FIF-VCD system can potentially replace HS in microsurgery, allowing the safe and effective connection of arteries and veins. Further studies are needed to confirm the clinical viability and effectiveness of the FIF-VCD system.

Leakage Benchmarking for Universal Gate Sets.

Errors are common issues in quantum computing platforms, among which leakage is one of the most-challenging to address. This is because leakage, i.e., the loss of information stored in the computational subspace to undesired subspaces in a larger Hilbert space, is more difficult to detect and correct than errors that preserve the computational subspace. As a result, leakage presents a significant obstacle to the development of fault-tolerant quantum computation. In this paper, we propose an efficient and accurate benchmarking framework called leakage randomized benchmarking (LRB), for measuring leakage rates on multi-qubit quantum systems. Our approach is more insensitive to state preparation and measurement (SPAM) noise than existing leakage benchmarking protocols, requires fewer assumptions about the gate set itself, and can be used to benchmark multi-qubit leakages, which has not been achieved previously. We also extended the LRB protocol to an interleaved variant called interleaved LRB (iLRB), which can benchmark the average leakage rate of generic n-site quantum gates with reasonable noise assumptions. We demonstrate the iLRB protocol on benchmarking generic two-qubit gates realized using flux tuning and analyzed the behavior of iLRB under corresponding leakage models. Our numerical experiments showed good agreement with the theoretical estimations, indicating the feasibility of both the LRB and iLRB protocols.

Airtightness of Estonian dwellings – median and base-values for heat loss estimation.

The field measurements of airtightness in Estonian detached houses and apartment buildings, conducted between 2003 – 2022, were combined into a large dataset for statistical analysis. The buildings (539 in total) constructed between 1810 and 2022 were classified based on dwelling type, building structure, number of storeys, year of construction, energy classification and compactness factors. The data was statistically analysed to determine the mean and median air leakage rates at 50 Pa and tested (Kruskal-Wallis test with post-hoc Conover test) for significant differences within the grouping factors. Buildings constructed after the enforcement of the compulsory Energy Performance certification have on average across all building structure types significantly lower mean air leakage rate (1.6 m3/(h·m2)) than older buildings (6.9 m3/(h·m2)), although log-wood and brick construction types feature slightly higher average air leakage rate. Previous experience with air leakage measurements help to achieve better airtightness on building site. A systematic and recurring measurement practice within a single construction company leads to significantly lower air leakage also for new concrete buildings. Detailed assessment of older buildings showed that all timber-based construction types had significantly higher air leakage rate along with higher variability compared to precast large concrete panel stone and small block wall and brick buildings. All apartment buildings built before 2010 had significantly lower air leakage rate compared to detached houses while there was no difference in new buildings. Along with the mean and median value a base value of air leakage rate q E50,base was calculated for all construction types and age groups including 50% of measured buildings around the mean within each group with 84 % confidence interval. The calculated mean, median and base values of air leakage rate provide a way for more accurate heat loss estimation at the district-level or building-level modelling of energy saving potential of different retrofitting strategies based on building age, construction type and other building information data.

A framework to simulate the blowout of CO2 through wells in geologic carbon storage

It is important to evaluate the risks associated with CO2 leakage in large scale carbon capture and storage (CCS) projects. Leaky wells are considered a major concern for potential CO2 leakage in geologic carbon storage. The most rapid and spectacular mode of CO2 leakage is the blowout of a CO2 storage well. The Sheep Mountain CO2 blowout in March 1982 is an example of this type of catastrophe wherein several thousand tons of CO2 were released into the atmosphere every day. The blowout was stopped only in early April. In the current work we present a numerical framework to simulate blowouts of CO2 wells accounting for the supercritical-liquid–gas–solid phase transitions of CO2 during the process. It is an in-house finite volume method based code for CO2 transport in open wells, relying on a hybrid Span–Wagner equations of state. We present extensive verification and validation of the code against numerical and experimental data in the literature. When applied to well blowouts, our numerical method is able to identify the locations along the well where CO2 transitions between its different phases. Our simulations show that while the heat transfer between CO2 and the casing has a significant impact on the transient characteristics of the blowout, it does not affect the steady-state leakage rate significantly. We also find that the CO2 leakage rate increases as the total depth of the well increases, with an average leakage rate of 2.09×104 tons per day across all the well depths simulated ranging between 1 km and 3.5 km. Our simulations show that when the temperature and pressure at the well bottom are appreciably lower than the geothermal temperature and hydrostatic pressure at the given depth, CO2 is released as dry ice at the wellhead. The dry ice modeled here has a significant time-averaged mass fraction of 30% at quasi-steady state, and causes rapid fluctuations in the CO2 leakage rate.

PERFORMANCE ANALYSIS OF A POINT-TOPOINT SYSTEM UNDER ACTIVE ATTACK

—In wireless communications, security issues have become difficult due to unchangeable and unpredictable nature of the wireless medium. There are many traditional cryptographic techniques which were used previously. The physical layer security used for ensuring secure wireless communications apart from the cryptographic techniques, which is achieved after proper understanding of the nature wireless channels. Classical information theoretic secrecy is one of the metrics followed, in which, we assume that there is no(zero) leaked information at the eavesdropper which means the information decoding probability at the eavesdropper is '0'. But, practically achieving classical information theoretic secrecy is not possible. So, this project deals with partial secrecy. The partial secrecy of a system is measured in terms of equivocation, which gives the information of the level at which the eavesdropper (active) is confused. It means that in partial secrecy, there is information leakage but the eavesdropper cannot exactly decode the original message. The new secrecy metrics used GSOP (generalized secrecy outage probability), AFE (average fractional equivocation) and AILR (average information leakage rate) altogether provides more comprehensive and in-depth understanding of the secrecy performance over the fading channels.

Design and Working Parameter Optimization of Pneumatic Reciprocating Seedling-Picking Device of Automatic Transplanter

To improve the seedling-picking efficiency of the vegetable transplanter and reduce the damage rate of the seedling pot, a reciprocating seedling-picking device driven by full air pressure was designed. In this paper, the structure and working principle of the pneumatic seedling-picking device are introduced. Through the mechanical analysis between the seedling-picking claw and the seedling pot, working parameters such as the stroke and driving force of the pneumatic seedling-picking claw clamping cylinder were determined. According to the action sequence of the seedling-picking mechanism, which is horizontally dispersed and longitudinally conveyed, the pneumatic control scheme of the seedling-picking and -dropping system was formulated. The simulation model for the control loop of the longitudinal cylinder was created with AMESim simulation software, and the simulation analysis was carried out. The Box–Behnken response surface design optimization method was used to determine the best operating parameters of the cylinder. The optimized peak value of shock vibration at the end of the cylinder was optimized from −65.64 mm·s−2 to 35.41 mm·s−2, proving that the optimization of pneumatic working parameters has a positive effect on the success rate of seedling picking. The bench test of the seedling-picking mechanism was conducted on 72-hole plug seedlings with two picking frequencies of 120 plants·min−1 and 144 plants·min−1, respectively, and the average seedling leakage rate, seedling damage rate, and seedling pot damage rate at different picking frequencies were counted. The experimental results show that under the two seedling-picking frequencies, the average success rate of seedling picking and throwing after optimization is increased from 96.4% and 92.4% to 97.9% and 95.3%, respectively. This is in line with the requirements of high-speed seedling picking and confirms the rationality of the seedling-picking mechanism design.

Collaborative Governance of Rural Relative Poverty under Blockchain and Back Propagation Neural Network

It aims at exploring the effect of coordinated relative poverty governance in rural areas based on blockchain and back propagation (BP) neural network, so that the living standard of rural areas can be significantly improved. In view of the shortcomings and defects existing in the rural relative poverty governance, artificial intelligence technologies such as blockchain and neural network are innovatively introduced to conduct intelligent storage and data visualization analysis on the rural relative poverty governance process. A visualized governance and mechanism innovation model of rural relative poverty data based on blockchain and BP neural network is constructed. Finally, its performance is analyzed through experiments. The results show that the accuracy of data visualization prediction of the proposed algorithm model reaches 94.31%. When the amount of data is 5.5 Mb, the calculation consumption of the proposed algorithm is 0.08 s, and the average leakage rate finally stabilizes below 10%. Therefore, the constructed poverty data visualization governance model can achieve good data transmission security performance while ensuring high classification accuracy. It can provide experimental basis and contribution for the intelligent development and mechanism innovation of rural relative poverty governance.

Advanced Autonomous Welding for Refabrication and Follow-On Testing of Previously Irradiated Nuclear Fuel

The performance of follow-on experiments using irradiated nuclear fuel at any point in its lifecycle is a critical step in understanding phenomena and behavior. Transient experiments with high-burnup fuel can deepen the understanding of fuel fragmentation, relocations, and dispersal under loss-of-coolant accidents. An advanced autonomous welding process to refabricate commercial fuel rods inside a hot cell was created and tested to enable flexible experiment approaches on fuels irradiated in commercial and test reactors. Irradiated light water reactor fuel test pins from experiments performed at the Advanced Test Reactor (ATR) at Idaho National Laboratory were used to demonstrate the refabrication process. The welding process was found to be sensitive to welding parameters but flexible such that multiple passes could be performed on the same location until a hermetic weld was obtained. The refabrication of rodlets and successful welds was also found to be sensitive to the preparation of the irradiated cladding and endcaps. Thorough defueling of the fuel at the weld location and proper sizing of the endcaps and backing material mitigated these issues. The use of strategically located heat sinks in contact with the cladding and endcap materials also increased welding and refabrication success. For this work, the test pins were sectioned to remove the original endcaps and fuel was removed from both ends of each rodlet. The reassembly of the rodlets was then completed in four steps, which included the press fitting of new endcaps, the circumferential welding of rodlet endcaps to the cladding, rodlet pressurization in a pressure chamber, and seal welding the rodlet under pressure. The integrity of the refabricated rodlets was then verified via helium leak checking inside a vacuum chamber. The advanced welding system is capable of refabricating rodlets up to 380 mm in length, and repressurizing them up to 15 500 kPa. The refabricated lengths of the rodlets used in this work ranged from 149 to 165 mm and the refabricated fuel stack heights ranged from 70.4 to 79.8 mm. The rodlets were pressurized with argon to an average pressure of 3617 kPa, and the average leak rate after refabrication was 6.7∙10−8∙cm3∙s−1.

Security in Diffusive Molecular Timing Channels: An Amount of Confusion Level Perspective

Secure transmission of information to a desired receiver is an important attribute of any molecular communication system. This paper analyzes the secrecy performance for a multi-particle diffusive molecular timing channel. We first obtain the fractional equivocation and then employ three standard secrecy performance metrics, namely, generalized secrecy outage probability, average fractional equivocation, and average information leakage rate to evaluate the secrecy performance of the channel in the presence of an eavesdropping user. We then propose a new secrecy performance metric, the amount of confusion level, which quantifies the severity of the confusion level at the eavesdropping user. Compared to the aforementioned metrics which are mainly based on the first-order statistics, the amount of confusion level is a second order measure that characterizes the eavesdropping effect in a better way, especially in environments with very small value of the Lévy noise parameter. The dependence of various secrecy metrics on various physical parameters, especially the Lévy noise parameter and the degradation rate of information molecules, is studied. Our analysis suggests that an increase in the value of each of these parameters results in an improvement in the secrecy performance. Numerical results corroborate the derived analytical findings.

Cooperative Friendly Jamming Techniques for Drone-Based Mobile Secure Zone.

Threats of eavesdropping and information leakages have increased sharply owing to advancements in wireless communication technology. In particular, the Internet of Things (IoT) has become vulnerable to sniffing or jamming attacks because broadcast communication is usually conducted in open-network environments. Although improved security protocols have been proposed to overcome the limitations of wireless-communication technology and to secure safe communication channels, they are difficult to apply to mobile communication networks and IoT because complex hardware is required. Hence, a novel security model with a lighter weight and greater mobility is needed. In this paper, we propose a security model applying cooperative friendly jamming using artificial noise and drone mobility, which are autonomous moving objects, and we demonstrate the prevention of eavesdropping and improved security through simulations and field tests. The Cooperative Friendly Jamming Techniques for Drone-based Mobile Secure Zone (CFJ-DMZ) can set a secure zone in a target area to support a safe wireless mobile communication network through friendly jamming, which can effectively reduce eavesdropping threats. According to the experimental results, the average information leakage rate of the eavesdroppers in CFJ-DMZ-applied scenarios was less than or equal to 3%, an average improvement of 92% over conventional methods.

Study on the preparation and application of phenolic resin-based filling composite materials in coal mines

ABSTRACT An in situ modification method is used to synthesize a new type of phenolic resin-based composite material used to fill goafs and seal air leaks in roadways. This was followed by scanning electron microscopy, oxygen index, and compression tests. The results show that when the aluminium hydroxide, Sd-31 silicone oil and methylene chloride are added to the phenolic resin in a mass fraction ratio of 8%:5%:3%, the overall performance of the composite material is the best. Compared with unmodified phenolic resin, the oxygen index and compressive strength of thecomposite material are increased by 40.16% and 3.5 times, respectively. The maximum reaction temperature of foaming and curing is also reduced from 120.3 to 87.2°C. To verify the performance of the new material, field tests were carried out at Matigou coal mine in Gansu, China. The average air leakage rate of the working face was reduced from 12.8 to 2.1 %.

Deep-Ultraviolet LEDs With All-Inorganic and Hermetic Packaging by 3D Ceramic Substrate

In this letter, an all-inorganic and hermetic packaging technology was proposed for deep-ultraviolet light-emitting diodes (DUV-LEDs). The package was fabricated by bonding the quartz cap on the three-dimensional (3D) ceramic substrate at low temperature. The bonding layer was formed by an inorganic adhesive and presented a reliable and dense state. The average air leakage rate of the packaging structure was 3.79 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-8</sup> Pa.m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> /s and the average tensile strength between quartz cap and ceramic substrate was 4.3 MPa. The peak emission intensity was at 280 nm and the peak width at half height was about 10 nm. At the current of 40 mA, the voltage was 5.63 V and the light output power was 3.0 mW. After the accelerated aging test, the light output power of packaged DUV-LEDs only decreased by 14.9%, while that of unpackaged reference decreased by 55.8%.

Secrecy Optimization for Diffusion-Based Molecular Timing Channels

Security in the context of molecular communication systems is an important design aspect that has not attracted much attention till date. This letter analyzes the information-theoretic secrecy of diffusive molecular timing channels when the distance of the eavesdropper is assumed to be random and uniformly distributed. Using an existing upper bound on the timing channel capacity, we calculate the optimal secrecy rate and optimal transmission rate for Bob which would help in achieving an improved secrecy throughput performance. Based on this optimal rate, we calculate the maximum achievable throughput. We then use this formulation to minimize the generalized secrecy outage probability (GSOP) by simultaneously maximizing the average fractional equivocation and minimizing the average information leakage rate. The numerical results show that while choosing the system parameters, there is always a trade-off between different performance metrics like GSOP, average fractional equivocation, and average information leakage rate. The proposed secrecy optimization provides a robust understanding of the physical layer secrecy at the molecular level, enabling the design of secure molecular communication systems.

Using particle swarm optimization algorithm to optimally locating and controlling of pressure reducing valves for leakage minimization in water distribution systems

The main objective of pressure management in a water distribution system (WDS) is to minimize leakages, bursts and maintain the required pressure at every node. One of the methods for pressure management is using pressure-reducing valves (PRV). This paper outlines an optimization-simulation approach to determine the optimum location and settings of the PRVs to control the pressure and minimize the leakage in WDSs. To solve the problem, the particle swarm optimization (PSO) tool was coupled with EPANET hydraulic simulation software in MATLAB environment. The results revealed that by observing all the regulations of the problem, through utilizing the proposed method for finding optimal location and regulating the PRVs, the network average leakage rate in a 24-h utilization period dropped by 23%. The performance of the PSO-based model in pressure management was compared with models based on three specific types of powerful algorithms including a genetic algorithm (GA) from the evolutionary algorithms (EA), artificial bee colony (ABC) from the swarm intelligence, and cultural algorithm (CA) from human behavior. The PSO-based model with the lowest objective function call compared to the other three algorithms, was able to reduce leakage compared to GA, ABC, and CA by 1.63, 3.45, and 8.53%, respectively. That shows the presented method is successful in regulating the pressure level to minimize network leakage.

Optimal Operational Scheduling of Available Partially Closed Valves for Pressure Management in Water Distribution Networks

This paper investigates an effective and practical method to define optimal operational scheduling of available Partially Closed Valves (PCVs) for pressure management in Water Distribution Networks (WDNs). The aim is to determine which of the valves and how much does it is opened every hour of the day to maximize the Network Pressure Reliability Index (NPRI) of WDNs. The Particle Swarm Optimization (PSO) algorithm is applied to find which of valves needs adjustment by using the Pipe Closure Index (PCI) in a calibration process, and the Ant Colony Optimization (ACO) algorithm is used to find the setting of valves. The developed models are prepared by linking the optimization algorithm with the hydraulic simulator (EPANET) in the MATLAB. A sample network and real WDN are used to validate the proposed method. The comparison of the results for the real WDN indicates that by using the proposed method, the average reliability index increases up to 32.6%, and the average leakage rate decreases up to 31.7%. So the proposed method is effective in increasing the reliability and decreasing the leakage rate of the network.