Type Of Discharge Research Articles

Gap distance of UHV substation in areas with an altitude of 5000 m and below

Abstract In view of the increasing energy consumption and power demand, the construction of UHV AC is growing rapidly, and the construction of the project is gradually advancing to higher altitudes. It is urgent to conduct research on typical gap discharge in substations at high altitudes. Combined with the engineering requirements, this paper corrects the test data at an altitude of 0 m according to GB/T 24842 standard through altitude correction and combines the discharge voltage requirements of various typical gaps in substations to obtain the minimum air gap distance in UHV substations at an altitude of 5000 m and below. The calculation results of the two altitude correction methods are compared and analyzed, and the applicability of the two methods is analyzed.

Machine learning for parameters diagnosis of spark discharge by electro-acoustic signal

Discharge plasma parameter measurement is a key focus in low-temperature plasma research. Traditional diagnostics often require costly equipment, whereas electro-acoustic signals provide a rich, non-invasive, and less complex source of discharge information. This study harnesses machine learning to decode these signals. It establishes links between electro-acoustic signals and gas discharge parameters, such as power and distance, thus streamlining the prediction process. By building a spark discharge platform to collect electro-acoustic signals and implementing a series of acoustic signal processing techniques, the Mel-Frequency Cepstral Coefficients (MFCCs) of the acoustic signals are extracted to construct the predictors. Three machine learning models (Linear Regression, k-Nearest Neighbors, and Random Forest) are introduced and applied to the predictors to achieve real-time rapid diagnostic measurement of typical spark discharge power and discharge distance. All models display impressive performance in prediction precision and fitting abilities. Among them, the k-Nearest Neighbors model shows the best performance on discharge power prediction with the lowest mean square error (MSE = 0.00571) and the highest -squared value ( ). The experimental results show that the relationship between the electro-acoustic signal and the gas discharge power and distance can be effectively constructed based on the machine learning algorithm, which provides a new idea and basis for the online monitoring and real-time diagnosis of plasma parameters.

GIS Partial Discharge Pattern Recognition Based on IWOA-SVM Algorithm

Abstract To effectively recognize partial discharge (PD) types in gas-insulated switchgear (GIS) equipment, a novel PD pattern recognition method is proposed. This method leverages an improved whale optimization algorithm (IWOA) to optimize the support vector machine (SVM). Firstly, typical PD defects were simulated in the GIS chamber. The PRPS results demonstrated significant differences among four PD defects. Secondly, multiple feature values of PD results were calculated for feature extraction. Finally, the IWOA-SVM algorithm was employed for the recognition of PD patterns in GIS. Experimental results indicate that the IWOA-SVM algorithm can effectively recognize different PD types and the predicted accuracy rate can reach 99.1667%, which is much higher than SVM and WOA-SVM algorithms, providing information to construction units for maintenance.

Driving voltage frequency and electrode material effects on electromagnetic radiation of the surface dielectric barrier discharge in the air

The electrical discharges are, among others, accompanied by the emission of electromagnetic waves of various frequencies. We studied this emission for the surface dielectric barrier discharge in the air. We used the discharge with one strip-driven electrode and a sinusoidal driving voltage of frequencies 5 and 10 kHz. From the spectra of emitted waves in the frequency band up to 3 GHz, we found that this type of discharge emits the radiation of frequencies below 500 MHz. In this frequency band, we focused on the effect of the driving voltage frequency and driven electrode material on the spectra of these waves. It was found that emitted radiation is distributed in several packages of frequencies, and an increase in the driving voltage frequency or voltage increases the power level of emitted radiation. Compared with the radiation spectrum of the discharge with an aluminium-driven electrode in the spectrum of the discharge with the copper-driven electrode, new peaks of various power levels and the shift of certain radiation frequencies to lower values appear. To understand the underlying mechanism of the discharge electromagnetic waves emission, we focused on the correlation between the electric component of emitted EMWs and the discharge electrical parameters as a function of time and discharge voltage.Graphical abstract

Transformer Fault Diagnosis Based on Intelligent Algorithm and Partial Discharge

Abstract As an important part of power transmission and transformation equipment and power systems, transformers’ operating conditions will have a direct impact on the stability and reliability of the power system. In view of the problems of high diagnosis cost and low accuracy of diagnosis results in existing fault diagnosis technology, this paper uses the pulse current method to detect the pulse signal generated by the discharge model based on the partial discharge experimental platform data, analyzes and studies the discharge characteristics of different discharge defects, and draws For the partial discharge phase distribution (PRPD) spectrum of each defect type, the statistical characteristic parameters characterizing the characteristics of the spectrum were extracted. The partial discharge statistical characteristics were used as classification feature quantities and input into three network models: RBF, GRNN, and PSO-GRNN. The results show that PSO-GRNN has a good recognition effect and is suitable for partial discharge type identification. It has important practical significance and application value for the all-round health management of power transformers.

Determinants of Bacterial Vaginosis: A Retrospective Study

Background: Among women who can have children, bacterial vaginosis (BV) is the most common cause ofabnormal vaginal discharge. Due to its high prevalence and morbidity, it is crucial to prevent BV by addressing its risk factors. Objective: This study aimed to determine the incidence and determinants of BV in the sexually transmitted infection (STI) division of the Dermatovenereology Department at Dr. Soetomo Hospital in Surabaya. Methods: This retrospective analytical observational study was conducted using a cross-sectional approach. Electronic data from 56 patients were included in the study, covering the period from 2019 to 2022. The patients were divided into two groups: BV patients and controls. BV patients were diagnosed with BV by fulfilling three out of four Amsel criteria, while controls with typical vaginal discharge. Results: The study included 34 BV patients and 22 control patients. Bivariate analysis showed a significant correlation between the incidence of BV and the number of sexual partners (p = 0.009) and the use of intrauterine devices (IUD) (p = 0.002). Multivariate analysis confirmed that both factors were determinants of BV incidence, with IUD use being the most dominant determinant (95% CI 1.86~135.02, p = 0.01). Conclusion: The study found that the use of IUDs and the number of sexual partners significantly determined BV incidence.

Enhancing fine particle removal by electrostatic precipitation from flue gas with a high PM concentration: Effect of various electrode configurations

Particle pollution has hazardous effects on air quality and human health, especially fine particle. However, the highly efficient removal of fine particles is an unsolved problem in electrostatic precipitators (ESPs). In this study, a transparent ESP was designed to investigate the effect of fine particles on the corona discharge performance and the role of ionic wind in particle migration. And five types of typical discharge electrodes were applied. The results showed that the presence of fine particles could weaken the corona current produced by electrode discharge. Among these electrodes, the spike electrode can reduce the adverse effect of the particle space charge. The maximum ionic wind velocity around the electrode tips and within the near-plate region could reached 5.67 m/s and 5.00 m/s under an applied voltage of 30 kV, respectively. Combining the effects of corona discharge and ionic wind, the collection efficiencies of fine particles decreased in the following order: spike electrode (medium needle) > spike electrode (longest needle) > arista electrode > spike electrode (shortest needle) > sawtooth electrode. In general, spike electrode discharge has better performance for particle charging and particle collection efficiency and is suitable for fine particle removal in ESPs. In addition, electrode configuration/arrangement optimization methods were proposed to enhance fine particle removal in ESPs.

The Potential of Cold Atmospheric Pressure Plasmas for the Direct Degradation of Organic Pollutants Derived from the Food Production Industry.

Specialized chemicals are used for intensifying food production, including boosting meat and crop yields. Among the applied formulations, antibiotics and pesticides pose a severe threat to the natural balance of the ecosystem, as they either contribute to the development of multidrug resistance among pathogens or exhibit ecotoxic and mutagenic actions of a persistent character. Recently, cold atmospheric pressure plasmas (CAPPs) have emerged as promising technologies for degradation of these organic pollutants. CAPP-based technologies show eco-friendliness and potency for the removal of organic pollutants of diverse chemical formulas and different modes of action. For this reason, various types of CAPP-based systems are presented in this review and assessed in terms of their constructions, types of discharges, operating parameters, and efficiencies in the degradation of antibiotics and persistent organic pollutants. Additionally, the key role of reactive oxygen and nitrogen species (RONS) is highlighted. Moreover, optimization of the CAPP operating parameters seems crucial to effectively remove contaminants. Finally, the CAPP-related paths and technologies are further considered in terms of biological and environmental effects associated with the treatments, including changes in antibacterial properties and toxicity of the exposed solutions, as well as the potential of the CAPP-based strategies for limiting the spread of multidrug resistance.

Are Ecological Risk Indices for Trace Metals Relevant for Characterizing Polluted Substrates in the Katangese Copperbelt (DR Congo) and for Assessment of the Performance of Remediation Trials?

This study aims to contribute to the characterization of Katangese Copperbelt’s (DR Congo) mining wastes and soils polluted with trace metals, using pollution indices and direct concentration measurements. This study also evaluated the use of these indices in assessing the success of remediation projects. Data from previous studies and samples collected from six types of discharge and one polluted soil were used to address the first objective. Soil and plant samples were collected at Kipushi and Penga Penga for the second objective. The results reveal very high concentrations of As, Cd, Co, Cu, Mn, Pb, and Zn in all mine tailings and polluted soils, compared with local references. The degree of contamination (DC) values (from 72 to 5440) and potential ecological risk (RI) values (from 549 to 162,091) indicate very high-risk situations associated with polluted discharges and soils. Regarding revegetation trials, the results show lower concentrations and RIs in tree rhizospheres compared with unamended areas at both sites. However, trace metal concentrations are higher in tree rhizospheres compared with local references, and RI values are in the considerable risk range for Penga Penga (RI = 533) and in the very high range (>1500) for Kipushi. Bioconcentration factor values are below 1, indicating low accumulation in roots, wood, and leaves, and low risk of contamination of the trophic chain. In this context, it seems that the pollution indices used are suitable for characterizing pollution and prioritization for remediation. However, their seems unsuitable for assessing the effectiveness of phytotechnology processes based on metal stabilization. Direct plant performance measurements combined with direct measurements of metals in substrates and plants to assess transfer and efficiency are more appropriate.

Analysis of changes in water quality and treatment effectiveness of seven major river basins in China from 2001 to 2020

The seven major river basins (the Yangtze River, the Yellow River, the Pearl River, the Songhua River, the Huai River, the Hai River and the Liao River) are the most important surface water resources in China, but there is a lack of quantitative analyses of water quality change trends, horizontal comparisons of governance effects, and systematic review of effective policies since the 21st century. Based on the water resources bulletin and environmental status bulletin issued by government departments, the changes in water quality, pollutant indicators and treatment effectiveness of seven major basins from 2001 to 2020 have been scientifically analyzed using mathematical and statistical methods. (1) Over the period 2001 to 2020, the overall water quality in the seven major river basins exhibited a gradual improvement. Different basins demonstrated varied growth values for Grade I-III water, reduction values for Grade IV-V, and inferior Grade V water. (2) Between 2001 and 2020, changes in sewage discharge volume and types led to adjustments in the main pollutant indicators of the seven basins. (3) The ranking of the pollution degree in the seven major basins exhibited dynamic changes but also remained relatively stable during specific periods or years. (4) Assessing the average annual growth rate of Grade I-III water and the average annual reduction rate of Grade IV-V and inferior Grade V water, the Huai River basin demonstrated the most outstanding governance effectiveness, while the Liao River basin, the Yellow River basin, and the Songhua River basin also achieved notable treatment results. (5) The improvement in water quality across the seven major river basins can be attributed to scientific planning, enhanced policies and regulations, surge in investment in water conservancy infrastructure, heightened environmental protection awareness, application of green production technology. To sum up, the research findings not only provide a scientific foundation for the governance and protection of the seven major basins but also offer a valuable reference for other developing countries to strike a balance between economic development and environmental protection.

Hospitalization information and burden of pediatric inpatients in transport accidents

BackgroundTransport accidents are one of the leading causes of child morbidity and mortality worldwide and represent a significant public health burden. This study aimed to investigate the hospitalization information and burden of pediatric inpatients in transport accidents in China.MethodsIn this study, we collected the cover page of the medical records of pediatric inpatients in transport accidents using the Futang Research Center of Pediatric Development (FRCPD) database from January 1, 2016 to December 31, 2021. Then, we extracted the epidemiological characteristics, including demographic characteristics, cases distribution, disease information, and hospitalization burden.ResultsAmong 36,455 included inpatients, males, aged 1–3 years, East China, July were dominant in different subgroups. In transport accidents, pedestrians were the most frequently type of injury (65.69%). Of all known lesions, craniocerebral/nerve injury was the more common results in pediatric inpatients in transport accidents (33.93%). In addition to pedal cyclists more susceptible to sport system injury, other types of injured person with transport accidents were mainly craniocerebral/nerve injury. In terms of the type of discharge, occupant of heavy transport vehicle or bus and people with craniocerebral/nerve injury had the highest mortality rate after hospitalization in all type and lesion of injured person groups, respectively. The largest hospitalization burden in the type of injured person was occupant of heavy transport vehicle or bus.ConclusionsThis study revealed that epidemiological characteristics and the main factor influencing the hospitalization information and burden of children with traffic accidents in China.

Unaccompanied Migrant Children in US Government Custody: 2014–2023

Between October 1, 2014, and March 1, 2023, the US Office of Refugee Resettlement (ORR) took custody of 568,890 unaccompanied migrant children. Drawing on a unique dataset that ORR produced in response to Freedom of Information Act requests and litigation, we provide the first comprehensive, long-term demographic study of the population of unaccompanied migrant children while in ORR custody. Our analysis reveals the children's differential treatment and experiences across time and demographic characteristics. We contextualize ORR's treatment of the children in its custody by identifying legal standards governing their care. We also examine how specific instances of legal, political, and social change in the United States correlate with fluctuations in the origin-based demographics of unaccompanied migrant children seeking refuge in the United States. Results highlight the differential treatment and intense uncertainty that unaccompanied migrant children face in the United States based on their age, gender, country and region of origin, ORR program placements, and discharge types.

Optimizing electrode arrangement in plasma actuators: a study on induced velocity and efficiency

This study investigates the performance of two types of multi-encapsulated electrode (MEE) plasma actuators, compared to typical dielectric barrier discharge (DBD) plasma actuators, in quiescent air. The objective is to determine whether the multiple encapsulated structure can enhance the performance of the plasma actuator. In the present paper, flow characteristics are investigated by using particle image velocimetry (PIV) and Schlieren visualisation. In addition, the distribution of body force over the gas volume based on the Navier–Stokes equations is calculated from velocity measurements. The obtained results demonstrate that the starting vortex behavior is influenced by electrode arrangement. Specifically, it can be observed that when the first encapsulated electrode is positioned closer to the exposed electrode, then a significantly higher induced velocity can be obtained compared to the baseline condition. In fact, the induced velocity can be increased by up to 1.5 times under this optimize configuration. These results highlight the importance of electrode arrangement in the plasma actuator design. Based on body force estimation, MEE plasma actuators exhibit a significantly higher momentum transfer, particularly in the wall normal direction. The investigation on the mechanical efficiency also reveals that the optimized configuration proposed in the present study can significantly enhance the efficiency. In fact, a four-fold increase in maximum efficiency compared to the typical configuration is observed. These results suggest that the proposed configuration could be considered a promising solution for improving the mechanical efficiency of plasma actuators.

Experimental study on Local Scour around Bridge Pier Models generated by Flash Floods carrying Debris

The analysis of local scouring around bridge piers currently is based on typical river flood discharges. However, extreme events like flash floods with high velocity and discharge, carry wooden debris that accumulates upstream of the bridge pier. This results in additional forces due to flow diversion and reduction in flow area, so impacting hydraulic structures and exacerbating the scouring process. The study objective was to examine the impact of debris transported by flash floods on the depth and distribution patterns of scouring around bridge piers. This research was conducted in a 15.5-m-length, 0.5-m-width, and 1.0-m-height glass flume, layered by 25 cm thick of sand which is d50=0.52 mm and σg=2.327. Flash flood simulations were conducted by flowing the water mixed with debris content of 0, 5, 10, and 15% to hit a sharp nose pier model which is installed in the channel. Scour depth was measured using point gauges at 50 points around the pier. The findings indicated that an irregular distribution pattern of scour is formed around the pier, and scour depth decrease when increasing debris content. It is necessary to corrected in the range of 0.65-1.43 for 0-15% debris content carried by the flash flood compared to normal flood.

Linear stability analysis of the electrostatic drift wave in the electron thermal internal transport barrier in EAST

An alternative local electrostatic gyrokinetic eigenvalue code is developed for the ion-temperature-gradient-driven mode, the trapped-electron mode (TEM), and the electron-temperature-gradient (ETG)-driven mode. It numerically solves the linear eigenvalue problem for the electrostatic drift waves in the Fourier transformed space and benchmarks well with the HD-7 code and FULL code. The linear ETG and TEM instabilities in the electron thermal internal transport barrier (eITB) with dominant electron heating in experimental advanced superconducting tokamak are analyzed by using this code. The linear analysis results are consistent with that from the critical electron-temperature-gradient threshold analysis. Moreover, the sensitivity of ETG and TEM instabilities to parameters during the eITB formation has been investigated. For the typical eITB discharge, it is found that the instability of ETG mode is more sensitive to the stabilizing effect of the electron–ion temperature ratio (τe), while the instability of TEM is more sensitive to the destabilizing effect of ηe. In addition, mixing length estimation of the turbulent transport in the eITB is also discussed, which suggests that the TEM may be saturated by other nonlinear effects than the resonance broadening.

Spectral diagnosis of underwater microsecond high-current pulsed discharge plasma

Underwater microsecond high-current pulsed discharge can generate powerful shock waves and a significant number of active ions, offering a wide range of applications. To analyse the characteristics of plasma channel formed by the discharge, this study established a comprehensive test platform and conducted spectral diagnosis for underwater high-current pulsed discharge. Considering the randomness of the pulsed arc discharge, the voltage and current waveforms under different discharge cases were measured, and the images and emission spectra of the plasma channel were obtained. The origin of the continuous emission of the initial spectra was analysed. A spectral fitting algorithm was proposed, which could separate the spectral lines into line emission of Hα and continuous background, and correct the self-absorption. The time-varying characteristics of electron density were obtained under three typical discharge cases, the possible errors caused by baseline shift were considered, and the influencing factors of line broadening were analysed. Under the test conditions of this study, the electron density of plasma channel was in the order of 1024–1025 m−3.

Innovative Approach for Detecting Early-Stage Partial Discharges in Instrument Transformers via Ultrasound and Random Forest Analysis

This article introduces a novel technique for detecting and classifying Partial Discharges in Instrument Transformers, addressing the gradual breakdown of external insulation in high-voltage electrical equipment through ultrasound measurements. The use of hand-held probe-microphones for ultrasonic sensing gains prominence for its versatility and online diagnostic capabilities. The proposed method combines insights into partial discharge types and the pollution level within the equipment, thereby transforming ultrasonic readings into useful information and facilitating informed decision-making. Laboratory tests simulate real-world conditions to which current and voltage transformers of 145 kV and 245 kV are subjected. These tests result in ultrasonic and apparent charge measurements, also known as Phase-Resolved Partial Discharges (PRPD). A random forest model achieves over 92 % accuracy in classifying ultrasonic signals into eight class: normal, light partial discharge, light corona, corona, light superficial, light saline pollution, moderate saline pollution and heavy saline pollution; enhancing the understanding and predictive maintenance of instrument transformers.

АТОМНО-ДИСЛОКАЦИОННАЯ МОДЕЛЬ УДАЛЕНИЯ ПОВЕРХНОСТНЫХ СЛОЕВ СТРУЙНЫМ ЭЛЕКТРОЛИТНО-ПЛАЗМЕННЫМ ПОЛИРОВАНИЕМ

This work is devoted to the development of a model for the removal of surface layers of anode material due to a jet electrolyte-plasma discharge formed by a hollow cathode. The results of studies of the main types of discharges that occur during the formation of jet electrolyte-plasma processing are presented. The influence of each type of discharge on the morphology of the surface layer of the anode-product was studied. The power, lifetime and energy of single discharges are estimated, and their influence on the surface is assessed. A theory has been proposed for the removal of surface layers by single discharges at the atomic dislocation level. Theoretical calculations are confirmed by the results of experimental studies and multiphysics simulations carried out in the COMSOL Multiphysics program. Practical research results confirm the possibility of reducing the roughness parameter Ra during jet electrolyte plasma by more than 20 times, while obtaining an extremely low parameter Ra of 0.019 μm. The area of application of the results of these studies may be the development of technological processes for dimensional and finishing processing of curved surfaces, such as blisks, turbine blades, and various products for household and medical purposes.

Underwater electrical wire explosions under different discharge types: An experimental study with high initial energy storage

In this study, underwater electrical explosions of aluminum wires of various sizes were carried out with an initial energy storage of ∼53.5 kJ. Two piezoelectric probes were adopted to record the pressure waveforms. The experiments were divided into different discharge types, and the statistical properties of the electrical and shock-wave parameters of the different discharge types were compared. The experimental results show that there are three discharge types, called type A (breakdown type), type B (transition type), and type C (matched type). The three types differ in the resistance characteristics of the plasma channel during the plasma growth process, which are determined from the average electrical field strength and the remaining energy in the circuit at the peak voltage. Shock waves from type C discharges are more likely to exhibit a higher peak pressure, a larger impulse, and a higher energy density than the other types. However, using a matched wire that matches a specific discharge type, a high peak pressure, large impulse, and high energy density can also be achieved under type A or type B discharges. For example, the maximum peak pressures at ∼33 cm under type B and type C discharges are 38.7 and 42.4 MPa, respectively. These results provide significant guidance for load selection in underwater electrical wire explosion engineering applications.

En-route charge scheduling for an electric bus network: Stochasticity and real-world practice

Bus electrification, with its high energy conversion efficiency and zero tailpipe emissions, has a significant impact on addressing the petroleum crisis and lowering carbon emissions in urban transportation. However, long charging times and uncertain operational risks hinder their wider adoption. This paper explores the robust en-route charge scheduling problem for electric buses to overcome uncertain energy consumption while ensuring charging accessibility. The problem is first described as a deterministic mixed-integer linear programming model that employs a time-of-use electricity price to balance the charging demand. Additionally, a robust counterpart model is formulated to account for stochastic energy. Numerical studies are designed to evaluate the proposed model in a real network, followed by a sensitivity analysis to investigate the impact of battery type, fleet composition, and depth of discharge on the charging schedule. The results show that the robust optimization model provides system feasibility against uncertainty with a comparable price and emissions.