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"leakage"
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Monitoring SFsub.6 Gas Leakage Based on a Customized Binocular System
Sulfur hexafluoride (SF[sub.6]) gas is extensively utilized as an insulating and arc-quenching medium in the circuit breakers and isolating switches of electrical equipment. It effectively isolates the circuits from the atmosphere and promptly extinguishes arcs. Therefore, the issue of SF[sub.6] gas leakage poses a significant threat to the related application fields, and the detection of SF[sub.6] gas leakage becomes extremely important. Infrared imaging detection offers advantages including non-contact, high precision, and visualization. However, most existing infrared detection systems are equipped with only one filter to detect SF[sub.6] gas. The images captured contain background noise and system noise, making these systems vulnerable to interference from such noises. To address these issues, we propose a method for monitoring SF[sub.6] gas leakage based on a customized binocular imaging (CBI) system. The CBI system has two filters, greatly reducing the interference of system noise and background noise. The first filter features the absorption resonant peak of SF[sub.6] gas. The second filter is used to record background noise and system noise. One aspect to note is that, in order to avoid the interference of other gases, the central wavelength of this second filter should keep away from the absorption resonant peaks of those gases. Accordingly, the central wavelengths of our customized filters were determined as 10,630 nm and 8370 nm, respectively. Then, two cameras of the same type were separately assembled with a customized filter, and the CBI prototype was accomplished. Finally, we utilized the difference method using two infrared images captured by the CBI system, to monitor the SF[sub.6] gas leakage. The results demonstrate that our developed system achieves a high accuracy of over 99.8% in detecting SF[sub.6] gas. Furthermore, the CBI system supports a plug-and-play customization to detect various gases for different scenarios.
Journal Article
A Selective Literature Review on Leak Management Techniques for Water Distribution System
Water Distribution System suffers from leakages causing social and economic costs. There is need of platform to manage water distribution system more efficiently by detecting, localizing and controlling the leakages even before or as soon as they occur, ensuring quality water services to the consumers. Since last two decades, high efforts have been made by researchers for the development of efficient leakage management techniques for reduction of water losses in distribution system. This paper provides a comprehensive analysis on leakage management techniques covering three aspects: leakage assessment, leakage detection and leakage control, with an objective to identify present challenges and future scope in their respected field. Role of smart water technologies for efficient leakages management in pipeline network is also examined and discussed. Conclusion is drawn regarding current leakage management techniques and proposals for future work and existing challenges are also outlined.
Journal Article
Novel Cascaded PV System with Common Mode Leakage Current Suppression
The problem of large common mode leakage current (CMLC) in cascaded H4 transformerless PV systems is investigated. Firstly, the reasons for the large CMLC of the cascaded system are analyzed, the common mode equivalent circuit is established, based on which the cascaded iH6 PV system is proposed, and the mechanism by which the cascaded iH6 system is able to effectively suppress the CMLC is analyzed and explained. Finally, the system is verified by simulation in Matlab/Simulink.
Journal Article
Ultrathin ferroic HfO2–ZrO2 superlattice gate stack for advanced transistors
With the scaling of lateral dimensions in advanced transistors, an increased gate capacitance is desirable both to retain the control of the gate electrode over the channel and to reduce the operating voltage
1
. This led to a fundamental change in the gate stack in 2008, the incorporation of high-dielectric-constant HfO
2
(ref.
2
), which remains the material of choice to date. Here we report HfO
2
–ZrO
2
superlattice heterostructures as a gate stack, stabilized with mixed ferroelectric–antiferroelectric order, directly integrated onto Si transistors, and scaled down to approximately 20 ångströms, the same gate oxide thickness required for high-performance transistors. The overall equivalent oxide thickness in metal–oxide–semiconductor capacitors is equivalent to an effective SiO
2
thickness of approximately 6.5 ångströms. Such a low effective oxide thickness and the resulting large capacitance cannot be achieved in conventional HfO
2
-based high-dielectric-constant gate stacks without scavenging the interfacial SiO
2
, which has adverse effects on the electron transport and gate leakage current
3
. Accordingly, our gate stacks, which do not require such scavenging, provide substantially lower leakage current and no mobility degradation. This work demonstrates that ultrathin ferroic HfO
2
–ZrO
2
multilayers, stabilized with competing ferroelectric–antiferroelectric order in the two-nanometre-thickness regime, provide a path towards advanced gate oxide stacks in electronic devices beyond conventional HfO
2
-based high-dielectric-constant materials.
In the standard Si transistor gate stack, replacing conventional dielectric HfO
2
with an ultrathin ferroelectric–antiferroelectric HfO
2
–ZrO
2
heterostructure exhibiting the negative capacitance effect demonstrates ultrahigh capacitance without degradation in leakage and mobility, promising for ferroelectric integration into advanced logic technology.
Journal Article
Single-crystalline metal-oxide dielectrics for top-gate 2D transistors
Two-dimensional (2D) structures composed of atomically thin materials with high carrier mobility have been studied as candidates for future transistors
1
–
4
. However, owing to the unavailability of suitable high-quality dielectrics, 2D field-effect transistors (FETs) cannot attain the full theoretical potential and advantages despite their superior physical and electrical properties
3
,
5
,
6
. Here we demonstrate the fabrication of atomically thin single-crystalline Al
2
O
3
(c-Al
2
O
3
) as a high-quality top-gate dielectric in 2D FETs. By using intercalative oxidation techniques, a stable, stoichiometric and atomically thin c-Al
2
O
3
layer with a thickness of 1.25 nm is formed on the single-crystalline Al surface at room temperature. Owing to the favourable crystalline structure and well-defined interfaces, the gate leakage current, interface state density and dielectric strength of c-Al
2
O
3
meet the International Roadmap for Devices and Systems requirements
3
,
5
,
7
. Through a one-step transfer process consisting of the source, drain, dielectric materials and gate, we achieve top-gate MoS
2
FETs characterized by a steep subthreshold swing of 61 mV dec
−1
, high on/off current ratio of 10
8
and very small hysteresis of 10 mV. This technique and material demonstrate the possibility of producing high-quality single-crystalline oxides suitable for integration into fully scalable advanced 2D FETs, including negative capacitance transistors and spin transistors.
By using intercalative oxidation techniques, stable, stoichiometric and atomically thin single-crystalline Al
2
O
3
films can be produced, which can be effectively used as a dielectric in top-gated field-effect transistors based on two-dimensional materials.
Journal Article
Study on the influence mechanism of air leakage on gas extraction in extraction boreholes
Borehole leakage is an important cause of gas extraction failure. In order to study the influence mechanism of borehole leakage on gas extraction, the borehole air leakage mode was studied, and a mathematical model was established to describe the borehole air leakage of the gas extraction. In addition, this paper also analyzed the change rules of borehole air leakage and gas extraction effect at different borehole sealing depth, negative extraction pressure, degree of fracture development and borehole sealing quality. Research shows that: (1) The hole sealing depth has a certain influence on the borehole air leakage and the gas extraction effect. As the hole sealing depth increased, the borehole air leakage gradually decreased. Moreover, the net amount of gas extraction gradually decreased, but the gas extraction concentration increased to some extent, and the increasing range gradually decreased. The reasonable sealing depth of this coal seam was 9∼10 m. (2) The negative pressure of borehole extraction has little influence on borehole air leakage and gas extraction. With the increase of the negative extraction pressure, the gas extraction net amount and borehole air leakage both increased, but the gas extraction concentration decreased. In the later stage of the gas extraction, the negative pressure can be properly reduced to improve the gas extraction effect. (3) The borehole sealing quality has a great influence on the borehole air leakage and gas extraction effect. With the improvement of the sealing quality, the coal-rock permeability gradually decreased. Moreover, the borehole air leakage significantly reduced, and the gas extraction concentration increased significantly. Therefore, attention should be paid to the selection and improvement of sealing materials and sealing techniques in the actual production so that the airtightness and sealing quality of the hole sealing section can be improved.
Journal Article
Leak Management in Water Distribution Networks Through Deep Reinforcement Learning: A Review
Leak management in water distribution networks (WDNs) is essential for minimising water loss, improving operational efficiency, and supporting sustainable water management. However, effectively identifying, preventing, and locating leaks remains a major challenge owing to the ageing infrastructure, pressure variations, and limited monitoring capabilities. Leakage management generally involves three approaches: leakage assessment, detection, and prevention. Traditional methods offer useful tools but often face limitations in scalability, cost, false alarm rates, and real-time application. Recently, artificial intelligence (AI) and machine learning (ML) have shown growing potential to address these challenges. Deep Reinforcement Learning (DRL) has emerged as a promising technique that combines the ability of Deep Learning (DL) to process complex data with reinforcement learning (RL) decision-making capabilities. DRL has been applied in WDNs for tasks such as pump scheduling, pressure control, and valve optimisation. However, their roles in leakage management are still evolving. To the best of our knowledge, no review to date has specifically focused on DRL for leakage management in WDNs. Therefore, this review aims to fill this gap and examines current leakage management methods, highlights the current role of DRL and potential contributions in the water sector, specifically water distribution networks, identifies existing research gaps, and outlines future directions for developing DRL-based models that specifically target leak detection and prevention.
Journal Article
Research on Leak Detection and Localization Algorithm for Oil and Gas Pipelines Using Wavelet Denoising Integrated with Long Short-Term Memory (LSTM)–Transformer Models
Traditional leakage prediction models for long-distance pipelines have limitations in effectively synchronizing spatial and temporal features of leakage signals, leading to data processing that heavily relies on manual experience and exhibits insufficient generalization capabilities. This paper introduces a novel leakage detection and localization algorithm for oil and gas pipelines, integrating wavelet denoising with a Long Short-Term Memory (LSTM)-Transformer model. The proposed algorithm utilizes pressure sensors to collect real-time pipeline pressure data and applies wavelet denoising to eliminate noise from the pressure signals. By combining LSTM’s temporal feature extraction with the Transformer’s self-attention mechanism, we construct a short-term average pressure gradient-average instantaneous flow network model. This model continuously predicts pipeline flow based on real-time pressure gradient inputs, monitors deviations between actual and predicted flow, and employs a pressure curve distance algorithm to accurately determine the leakage location. Experimental results from the Jilin-Changchun long-distance oil pipeline demonstrate that the model possesses superior leakage warning and localization capabilities. Specifically, the leakage prediction accuracy reaches 99.995%, with a leakage location error margin below 2.5%. Additionally, the model can detect leaks exceeding 0.6% of the main pipeline flow without generating false alarms during operation.
Journal Article
Development law of air leakage fractures in shallow coal seams: a case study in the Shendong Coalfield of China
Continuous air leakage from ground mining-induced cracks is a significant cause of coal spontaneous combustion, low oxygen at the working face and other disasters in shallow coal seams. This paper studies mining-induced cracks and air leakage caused by the repeated mining of shallow coal seams at the Bulianta coal mine, Shendong Coalfield, China. A similar simulation experiment was carried out in the laboratory, and then the ground mining-induced cracks were observed and the crack air leakage was detected. The results showed that the surface air flowed into the composite goaf before the fractures redeveloped to the surface during the process of lower coal seam mining. Due to the different development processes of vertical fractures in various regions, the width of the vertical fractures in the boundary area of the overlying goaf increases significantly after the repeated mining of coal seams, while the vertical fractures in the central area of the overlying goaf experience almost no change. The distribution of the surface air leakage cracks is in the shape of “回”. Graben-type cracks and half-graben-type cracks are surface air leakage cracks, which are the focus of surface air leakage problems, especially the half-graben-type cracks. The results are important in engineering for reducing air leakage from surface mining-induced cracks.
Journal Article