Leakage in water distribution systems is an important issue which is affecting water companies and their customers worldwide. It is therefore no surprise that it has attracted a lot of attention by ...both practitioners and researchers over the past years. Most of the leakage management related methods developed so far can be broadly classified as follows: (1) leakage assessment methods which are focusing on quantifying the amount of water lost; (2) leakage detection methods which are primarily concerned with the detection of leakage hotspots and (3) leakage control models which are focused on the effective control of current and future leakage levels. This paper provides a comprehensive review of the above methods with the objective to identify the current state-of-the-art in the field and to then make recommendations for future work. The review ends with the main conclusion that despite all the advancements made in the past, there is still a lot of scope and need for further work, especially in area of real-time models for pipe networks which should enable fusion of leakage detection, assessment and control methods.
Sulfur hexafluoride (SFsub.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 SFsub.6 gas leakage poses a significant threat to the related application fields, and the detection of SFsub.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 SFsub.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 SFsub.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 SFsub.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 SFsub.6 gas leakage. The results demonstrate that our developed system achieves a high accuracy of over 99.8% in detecting SFsub.6 gas. Furthermore, the CBI system supports a plug-and-play customization to detect various gases for different scenarios.
Remote vital sign detection using Doppler radar has gained increasing interest over the years. However, challenges remain in improving radar system sensitivity to extend the detection range. In this ...article, we analyze noise contributions in a dual-PLL low-IF Doppler radar system and identify RF leakage/coupling as a major component of the system noise floor. This effect results in negligible SNR improvement when the transmit output power is increased beyond a certain threshold. By applying RF leakage/coupling cancellation through phase and magnitude adjustments, we demonstrate significant improvements to radar system performance. Furthermore, we propose and validate an automatic RF leakage cancellation scheme. The proposed technique is shown to achieve a vital-sign-sensing range of <inline-formula> <tex-math notation="LaTeX">4</tex-math> </inline-formula> m under a very low transmit power of <inline-formula> <tex-math notation="LaTeX">-</tex-math> </inline-formula>31 dBm and with a high confidence level of three beats per minute against the ground truth measured by an oximeter sensor.
Pipeline transportation of hydrogen-blended natural gas is susceptible to leakage or rupture accidents caused by pipeline construction, corrosion, and hydrogen embrittlement, posing significant ...threats to the environment, human safety, and property. This paper improves the model of non-adiabatic pipeline leakage to study the flow characteristics of hydrogen-blended natural gas leakage, and its accuracy is validated using OLGA software and experiment data. The impact of the heat transfer coefficient, initial pressure and hydrogen blending ratio on the leakage flow characteristics is also analyzed. The findings indicate that the initial pressure in the pipe increases linearly at 0.5 MPa and the mass leakage velocity decreases linearly at a rate of nearly 9 kg/s; meanwhile, the temperature drop in the pipe and the overall leakage time increase. An increased hydrogen blending ratio corresponds to lower mass leakage velocity and shorter leakage time. The maximum dangerous distance of pure methane pipeline leakage is greater than that of a pure hydrogen pipeline. Furthermore, changes in the heat transfer coefficient predominantly affect the temperature inside the pipe.
•The non-adiabatic leakage model of natural gas pipeline is improved.•The variation law of parameters in pipeline leakage process is discussed.•The effects of heat transfer, initial pressure and hydrogen blended ratio on pipeline leakage flow are studied.
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.
Heavy-ion microbeams are employed for probing the radiation-sensitive regions in commercial silicon carbide (SiC) vertical double-diffused power (VD)-MOSFETs with micrometer accuracy. By scanning the ...beam spot over the die, a spatial periodicity was observed in the leakage current degradation, reflecting the striped structure of the power MOSFET investigated. Two different mechanisms were observed for degradation. At low drain bias (gate and source grounded), only the gate-oxide (at the JFET or neck region) is contributing in the ion-induced leakage current. For exposures at drain-source bias voltages higher than a specific threshold, additional higher drain leakage current is observed in the p-n junction region. This provides useful insights into the understanding of basic phenomena of single-event effects in SiC power devices.
Leakage of private information has become a threat to the security of computing systems. It has become a common security requirement that a cryptography scheme should withstand various leakage ...attacks, even the continuous leakage attacks. However, in the current constructions on the (continuous) leakage-resilient identity-based encryption (CLR-IBE) scheme, the leakage parameter is a fixed value. Aiming to solve these problems, in this study, the authors show how to construct the CLR-IBE scheme, and the adaptive chosen-ciphertext attacks security of proposed construction can be proved in the standard model. To further improve the practicability of CLR-IBE scheme, they design an improved IBE scheme with continuous leakage amplified property, and the leakage parameter has an arbitrary length.
Leakage current minimization is one of the most important considerations in transformerless photovoltaic (PV) inverters. In the past, various transformerless PV inverter topologies have been ...introduced, with leakage current minimized by the means of galvanic isolation and common-mode voltage (CMV) clamping. The galvanic isolation can be achieved via dc-decoupling or ac-decoupling, for isolation on the dc- or ac-side of the inverter, respectively. It has been shown that the latter provides lower losses due to the reduced switch count in conduction path. Nevertheless, leakage current cannot be simply eliminated by galvanic isolation and modulation techniques, due to the presence of switches' junction capacitances and resonant circuit effects. Hence, CMV clamping is used in some topologies to completely eliminate the leakage current. In this paper, several recently proposed transformerless PV inverters with different galvanic isolation methods and CMV clamping technique are analyzed and compared. A simple modified H-bridge zero-voltage state rectifier is also proposed, to combine the benefits of the low-loss ac-decoupling method and the complete leakage current elimination of the CMV clamping method. The performances of different topologies, in terms of CMV, leakage current, total harmonic distortion, losses and efficiencies are compared. The analyses are done theoretically and via simulation studies, and further validated with experimental results. This paper is helpful for the researchers to choose the appropriate topology for transformerless PV applications and to provide the design principles in terms of common-mode behavior and efficiency.
Gate leakage mechanisms in AlInN/GaN and AlGaN/GaN metal insulator semiconductor high-electron-mobility transistors (MIS-HEMTs) with SiN x as gate dielectric have been investigated. It is found that ...the conduction in the reverse gate bias is due to Poole-Frenkel emission for both MIS-HEMTs. The dominant conduction mechanism in low to medium forward bias is trap-assisted tunneling while it is Fowler-Nordheim tunneling at high forward bias. However, conduction near zero gate bias is dominated by defect-assisted tunneling for both sets of MIS-HEMTs. The gate leakage current is primarily dependent on the properties of the gate dielectric material and dielectric/ semiconductor interface rather than the barrier layer. A model is proposed for the gate leakage current in GaN-based MIS-HEMTs, and the method to extract the related model parameters is also presented in this paper. The proposed gate current model matches well with the experimental results for both AlInN/GaN and AlGaN/GaN MIS-HEMTs over a wide range of gate bias and measurement temperature.
Pointwise Maximal Leakage Saeidian, Sara; Cervia, Giulia; Oechtering, Tobias J. ...
IEEE transactions on information theory,
12/2023, Letnik:
69, Številka:
12
Journal Article
Recenzirano
Odprti dostop
We introduce a privacy measure called pointwise maximal leakage , generalizing the pre-existing notion of maximal leakage , which quantifies the amount of information leaking about a secret X by ...disclosing a single outcome of a (randomized) function calculated on X . Pointwise maximal leakage is a robust and operationally meaningful privacy measure that captures the largest amount of information leaking about X to adversaries seeking to guess arbitrary (possibly randomized) functions of X , or equivalently, aiming to maximize arbitrary gain functions. We study several properties of pointwise maximal leakage, e.g., how it composes over multiple outcomes, how it is affected by pre-and post-processing, etc. Furthermore, we propose to view information leakage as a random variable which, in turn, allows us to regard privacy guarantees as requirements imposed on different statistical properties of the information leakage random variable. We define several privacy guarantees and study how they behave under pre-processing, post-processing and composition. Finally, we examine the relationship between pointwise maximal leakage and other privacy notions such as local differential privacy, local information privacy, f -information, and so on. Overall, our paper constructs a robust and flexible framework for privacy risk assessment whose central notion has a strong operational meaning which can be adapted to a variety of applications and practical scenarios.
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