Occurrence Of Discharges Research Articles

The Influence of the Gap Phenomenon on the Occurrence of Consecutive Discharges in WEDM Through High-Speed Video Camera Observation

The Wire Electrical Discharge Machining (WEDM) process is an accurate method for manufacturing high-added-value components for industry. Continuous developments in the process have resulted in specialized machines used in sectors such as aerospace and biomedical engineering. However, some fundamental aspects of the discharge process remain unresolved. This work aims to study the influence of discharge location and bubble expansion on the occurrence of subsequent discharges. A high-speed video camera observation system was constructed to capture images of each discharge. From the acquired images, an algorithm was devised to determine the discharge location based on grayscale analysis. Moreover, the voltage and current waveforms of the discharges and the framing signals of the high-speed video camera were then obtained using an oscilloscope. Synchronizing the observation images and signals allowed for calculating the delay time for each single discharge. The results indicate that most of the discharges occurred near the boundary of the bubble and during bubble expansion. This finding has been observed for a variety of machining conditions and can be explained by the effect of the debris particles concentrated at the bubble boundary. This study provides useful information for better understanding the discharge process in WEDM.

Localization of partial electrical discharges using compressive spherical frequency-difference beamforming.

Accurate localization of partial electrical discharges is essential for the diagnosis of high-voltage systems. The current study achieves this by employing an acoustic sensor array and a beamforming approach. The occurrence of a partial discharge is accompanied by the emission of high-frequency sounds in the ultrasonic range, making localization a challenging task requiring many sensors to avoid spatial aliasing. Compressive frequency-difference beamforming, as previously proposed, can be effective in addressing this issue. We expand the method to include near-field localization by utilizing a spherical wave and propose a two-step normalization process. This eliminates the bias associated with nonplanar waves and standardizes the field variables, thereby preserving only the phase and relative amplitude information. A distributed algorithm based on the alternating direction multiplier method is used to solve the associated convex optimization problem. The proposed method is demonstrated using simulated and experimental data.

Partial Discharge Detection Technique Based on Full Convolutional Network with Channel-wise Convolution and Channel Mixing

Abstract The occurrence of partial discharge (PD) serves as an indication of power equipment failure, which, if not given due attention, may result in severe power accidents. Traditionally, the detection of PD involves applying various pre-processing techniques to the original signal and extracting specialized signal features that are subsequently classified using a classifier. The process is intricate and demands extensive expertise. One drawback of the conventional detection approach lies in its failure to consider the information conveyed between the phases of a three-phase electrical signal during the process of identifying PD in medium voltage three-phase cables. The present study proposes a novel method for detecting PDs, which is based on channel-wise convolution and channel mixing(C2CM) using full convolutional networks. Firstly, a set of pulses for each phase of a three-phase signal is extracted and combined to form a three-phase pulse set, serving as the input to the network. Subsequently, we introduce a FCN-C2CM network designed specifically for PD detection, capable of learning both the time-domain features of the input signal and the phase features of the three-phase signal, thereby enhancing recognition accuracy. We evaluated our approach using online testing tools on publicly available datasets, with experimental results demonstrating its superiority over existing.

Variability of cortico-cortical evoked potentials in the epileptogenic zone is related to seizure occurrence.

Cortico-cortical evoked potentials (CCEPs) were described as reproducible during trains of single-pulse electrical stimulations (SPES). Still, few studies described a variability of CCEPs that was higher within the epileptogenic zone (EZ). This study aimed at characterizing the relationship of CCEP variability with the occurrence of interictal/ictal epileptiform discharges at the temporal vicinity of the stimulation, but not during the stimulation, by effective connectivity modifications. We retrospectively included 20 patients who underwent SPES during their stereo-electroencephalography (SEEG). We analyzed the variability of CCEPs by using the post-stimulation time course of intertrial standard deviation (amplitude) and the timing of peak amplitude signal of CCEP epochs (latency). Values were corrected for the Euclidian distance between stimulating/recording electrodes. Receiver operating characteristics curves were used to assess the relationship with the EZ. The link between CCEP variability and interictal discharges occurrence, seizure frequency prior to the SEEG recording, and number of seizures during SEEG recording was assessed with Spearman's correlations. A relationship was demonstrated between the EZ and both the distance-corrected latency variation (area under the curve (AUC): 0.73-0.74) and the distance-corrected amplitude variation (AUC: 0.71-0.72) and both were related with the occurrence of seizures. Seizures before/during SEEG impact the dynamics of effective connectivity within the epileptogenic network by reducing the variability of CCEP latency/amplitude when the seizure frequency increases. It suggests a strengthening of the epileptogenic network with the occurrence of many seizures. These findings stress the importance of early epilepsy surgery at a time when the network organization has not yet been complete.

Recent progress of JT-60SA project toward plasma operation

Abstract Superconducting tokamak JT-60SA plays an essential role in fusion research and development by supporting and complementing ITER project, providing directions to the DEMO design activity and fostering next generation scientists and engineers. Since the incident of the Equilibrium Field coil #1 during the Integrated Commissioning (IC) in March 2021, both EU and JA Implementing agencies (IAs) have examined how to ensure safety operation of JT-60SA by mitigating the risk of possible discharge occurrence inside the cryostat. Based on the experience of the Global Paschen tests, the IAs have established a strategy of risk mitigation measures, which is a combination of (i) reinforcement of insulation, (ii) avoiding unnecessary voltage application to the coil systems and (iii) immediate de-energization of the coils when deteriorated vacuum condition is detected. Thanks to the considerable efforts of the Integrated Project Team (IPT) members, the IC restarted in May 2023. After the confirmation of superconducting state of coil systems (TF, EF and CS), the coil energization test and the plasma operation (OP-1) starts. The first plasma was successfully achieved on 23 October 2023 with a limited value of applied voltage and current to the coils. The plasma configuration control will be also confirmed with low plasma current and low auxiliary heating power conditions. Based on the IO-F4E-QST collaboration, activities of JT-60SA have been shared with the IO and provided an important lesson learned for ITER assembly and commissioning, and will provide an outstanding contribution to fusion research at large. After OP-1, Maintenance & Enhancement phase 1 (M/E-1) starts from January 2024, in which in-vessel components are installed, and heating system and diagnostic system are extensively upgraded to allow high power heating experiment planned in OP-2. In order to make the best use of JT-60SA, newly organized JT-60SA experiment team will refine the research plan in the future high heating power operation phase.

Detecting and Locating Corona Discharges in Low-Pressure Aircraft Environments Using Optical Sensors

Today, there is a clear trend toward electrification of transportation systems, including aircraft. Due to the enormous power requirements, they must operate at high voltages. However, the combined effect of higher voltage levels and low pressure environments is conducive to the occurrence of electrical discharges in electrical systems. Therefore, there is an urgent need to develop cost-effective systems to detect the discharges in the early stages before major failures can occur. This paper compares two optical sensors for early discharge detection in a simulated aircraft environment. The experimental study is performed in a low pressure chamber using a needle plane electrode. The pressure is changed from that corresponding to ground level to that corresponding to flight altitude, i.e., from 100 kPa to 20 kPa. The effect of the supply frequency is also studied, since modern aircraft operate in a wide range of frequencies up to about 800 Hz. Both variables, especially pressure, have shown significant effects on the CIV value. The results have also shown a similar sensitivity of both sensors for all the experimental conditions analysed, allowing a fast and sensitive detection and localization of incipient electrical discharge activity.

Simulation study of the effect of electrode polarity on microscale corona discharge characteristics

Abstract The occurrence and application scenarios of micro-scale corona discharge are diverse, and the effect of micro-scale corona discharge mechanism and needle electrode polarity on corona discharge characteristics is still unclear. This paper establishes a microscale simulation model of pin-plate DC positive and negative corona fluid chemical reactions. The phenomenon of positive and negative corona discharge is being investigated. The internal discharge mechanism is analyzed from the microscopic point of view. Results demonstrate that positive corona discharge generates space charges that reduce the electric field strength between the needle electrode and amplify it between the plate electrodes. In contrast, negative corona discharge exhibits the opposite effect. The number of charged particles produced by microscale negative corona discharge is larger than that produced by positive corona, and the discharge phenomenon is more intense than that of positive corona. Under the simulation conditions in this paper, the ionization reaction rate of micro-scale positive and negative corona rises rapidly at the initial discharge. It will gradually remain stable after experiencing an upward pulse. The pulse peak value generated by micro-scale negative corona discharge is much higher than that of positive corona, and the pulse width of negative corona discharge is about half smaller than that of positive corona, which can reach a stable corona discharge state faster.

An automatic robot for ultrasonic partial discharge detection of gas-insulated switchgear

PurposeGas-insulated switchgear (GIS) stands as a pivotal component in power systems, susceptible to partial discharge occurrences. Nevertheless, manual inspection proves labor-intensive, exhibits a low defect detection rate. Conventional inspection robots face limitations, unable to perform live line measurements or adapt effectively to diverse environmental conditions. This paper aims to introduce a novel solution: the GIS ultrasonic partial discharge detection robot (GBOT), designed to assume the role of substation personnel in inspection tasks.Design/methodology/approachGBOT is a mobile manipulator system divided into three subsystems: autonomous location and navigation, vision-guided and force-controlled manipulator and data detection and analysis. These subsystems collaborate, incorporating simultaneous localization and mapping, path planning, target recognition and signal processing, admittance control. This paper also introduces a path planning method designed to adapt to the substation environment. In addition, a flexible end effector is designed for full contact between the probe and the device.FindingsThe robot fulfills the requirements for substation GIS inspections. It can conduct efficient and low-cost path planning with narrow passages in the constructed substation map, realizes a sufficiently stable detection contact and perform high defect detection rate.Practical implicationsThe robot mitigates the labor intensity of grid maintenance personnel, enhances inspection efficiency and safety and advances the intelligence and digitization of power equipment maintenance and monitoring. This research also provides valuable insights for the broader application of mobile manipulators in diverse fields.Originality/valueThe robot is a mobile manipulator system used in GIS detection, offering a viable alternative to grid personnel for equipment inspections. Comparing with the previous robotic systems, this system can work in live electrical detection, demonstrating robust environmental adaptability and superior efficiency.

THE CORRELATION BETWEEN KNOWLEDGE AND BEHAVIOR OF VULVA HYGIENE WITH PATHOLOGICAL LEUKORRHEA INCIDENCE

Vulva hygiene is important to prevent pathological vaginal discharge. Adolescent girls are susceptible to such discharge due to insufficient awareness of proper hygiene practices. A preliminary study identified instances of improper wiping techniques and failure to adequately dry the vulva before donning underwear among students. Moreover, some students reported experiencing genital itching. The purpose of this study was to determine the correlation between knowledge and behavior of vulva hygiene with pathological vaginal discharge This study employed a correlational cross-sectional design. The population consisted of 52 female students at Al-Hasani Islamic Boarding School, selected through total sampling. Data were collected using validated and reliable questionnaires. Statistical analysis utilized Kendall's Tau correlation test. This research has passed an ethical review with letter number 1450/UN22.9/PG/2024 which considers research ethics in the form of informed consent, anonymity, privacy, confidentiality, justice, and beneficience. The results are 65.4% of respondents had good knowledge of vulva hygiene, 53.8% exhibited good vulva hygiene behavior, and 50% experienced pathological leucorrhea. Correlation analysis revealed no significant correlation between knowledge (ρ value = 0.087) or behavior (ρ value = 0.582) of vulva hygiene and pathological leucorrhea incidence. Further research is needed regarding factors associated with the occurrence of pathological vaginal discharge.

Analysis of capacitive discharges in motor bearings under different operation conditions

AbstractDespite being a well‐known problem, bearing faults are still one of the major challenges that the industry face. The growing use of voltage source inverters imposed the alertness of possible bearing damage due to their high‐frequency signals. The aim of this paper is to investigate the effect of capacitive discharges on a rolling element bearing to obtain a series of faulty bearings with different deterioration levels. An ageing test bench is built to generate bearing roughness using Electric Discharge Machining. The purpose is to study the effect of operation conditions, such as frequency of drive, amplitude of shaft voltage, radial load level as well as rotational speed, on the capacitive discharge occurrence within the bearing. Having the desire to further understand this phenomenon, the influence of each parameter on the discharge activity and the discharge waveform is analysed. A worst‐case scenario is conducted and applied to a series of bearings. Finally, the bearing damage is examined, and a quantitative fault detection method is presented based on a microscopic inspection of the bearing's surface.

Optimizing the Shape of the Spinning Electrode for Needleless Coaxial Electrospinning

This work deals with designing the optimal shape of the spinning electrode to optimize the distribution of the electric field and suppress the formation of corona discharges on the surface of the electrode during electrospinning using direct current (DC). Some of the solutions used for electrospinning are solved in flammable solvents, such as PVB; therefore, corona discharges are hazardous, as they cause sparks that can cause fires and explosions. The shape optimization was carried out on a plate weir electrode, which uses the principle of free surface spinning. Using the electric field simulation, an analysis of the plate weir spinner was carried out, and its optimization was aimed at minimizing the occurrence of corona discharges, which negatively affect the spinning process. Based on the simulations’ results, the spinning electrode design parameters were adjusted so that an even distribution of the electric field over the entire active surface of the electrode was ensured, and the incidence of corona discharges was prevented. A laboratory experiment was used to validate the function of the design changes in the spinning electrode.

Discharge mitigation methods in MPGD-based detectors

This work reviews various methods used to minimize the probability of discharge occurrence in MPGDs or to mitigate the effect of spark discharges on the detector system. These include techniques that can reduce the probability that the fundamental discharge limits of MPGD structures are reached during detector operation, methods based on the HV scheme optimization, or the implementation of resistive electrodes to enhance local discharge quenching capabilities in an amplification structure. In addition, design optimization and quality control methods to ensure stable, long-term operation of an MPGD-based detector, are considered.

What is happening with frequency and occurrence of the maximum river discharges in Bosnia and Herzegovina?

In this study, we explored the frequency and occurrence rate of maximum river discharges in the Una and Sana rivers, to understand hydrological variations amidst climate change. We categorized maximum discharges into severe (Una River M1 > 98.2 m3/s; Sana River M1 > 118.2 m3/s) and extreme (Una River, M2, > 123.4 m3/s; Sana River M2 > 246.4 m3/s) events, and identified trends in these events, crucial for assessing environmental impacts. Our findings reveal a nuanced pattern: both rivers experience an increase in severe events from 58 to 55 and 56 to 54 days return period respectively, indicating complex hydrological dynamics. The trends underscore the significant shifts in annual event occurrences, the evolving nature of river systems and underscore the necessity for adaptive management strategies.

Surgical Closure of Equine Abdomen, Prevention, and Management of Incisional Complications.

Although rarely fatal, complications of ventral midline laparotomy incision in equine patients increase hospitalization cost and duration and may jeopardize return to athletic function. Therefore, many techniques have been developed to reduce their occurrence and expedite their resolution when they occur. Our technique of celiotomy incision closure includes the use of tension sutures (vertical U mattress) of polyglactin 910 on the linea alba, which is then apposed by polyglactin 910 interrupted sutures or a simple continuous pattern suture with a stop midway before routine closure of the superficial layers. The celiotomy incision is protected by an elastic bandage during the immediate postoperative period. This technique has been associated with favorable results: 5.3% confirmed incisional infections after a single celiotomy and 26.7% after repeat celiotomy. The overall incisional complication (serous/sanguineous discharge, hematoma, infection, hernia formation, and complete wound breakdown) occurrence was 9.5% and 33.3% after single and repeat laparotomy, respectively. In cases considered more susceptible to infection (early relaparotomy or laparotomy incisions longer than 30 cm), negative pressure therapy was found easy to apply on closed incisions. No detrimental effects were observed. However, the potential prophylactic benefit of this therapy needs to be confirmed in a larger group. In infected laparotomy wounds requiring drainage, the use of negative pressure therapy seemed to have a positive effect on the formation of granulation tissue. However, there was no control group to allow statistical confirmation. Finally, one case of complete breakdown of the laparotomy incision was managed by stainless steel retention sutures, the application of negative pressure therapy, and a hernia belt. At re-evaluation 15 months post-surgery, several small hernias were detected, but the horse had returned to his previous level of sports performance and had not shown any episode of colic.

A method for calculating space charge distribution in ultra-high voltage direct current transmission lines based on the transport of diluted species theory

The occurrence of corona discharge in ultra-high-voltage direct current transmission lines results in the generation of space charge, which significantly affects the nearby electromagnetic environment. To investigate the micro-physical mechanisms of discharge and provide better guidance for the calculation of the ground ion current density and total electric field, a method based on the theory of the transport of diluted species is proposed. This method enables the visualization and analysis of the movement process of space charge in air medium, as well as the calculation of the total electric field below the transmission lines. To validate the effectiveness of this algorithm, experimental tests of the total electric field are conducted on actual transmission lines. The experimental results demonstrate that the algorithm not only highlights the evident differences in the transient microscopic processes between positive and negative corona discharges but also accurately calculates the total electric field below the transmission lines. In addition, considering the weather conditions in the Chongqing region, relevant recommendations are provided under the influence of wind speed, aiming to offer protection guidelines for individuals engaged in activities near transmission lines.

Examining electrical equivalent circuit models of insulators in transmission lines under pollution conditions: a comprehensive study and analysis

This research presents a comprehensive study investigating the behavior of insulators in transmission lines under various pollution conditions. Utilizing equivalent electrical circuits, the analysis aims to understand the impact of pollution on insulator performance, which is crucial for maintaining the reliability and efficiency of power transmission systems. By providing valuable insights into the relationship between pollution and insulator behavior, this study contributes to the development of improved strategies for mitigating the effects of pollution on transmission lines, ultimately enhancing the overall safety and stability of electrical power networks. The study focuses on a digital model that enables the visualization of potential and electric field distribution within a series of glass insulators utilized in Algerian electrical grids. Initially, a parallel RC network equivalent circuit was devised and its parameters were determined through finite element analysis using Comsol Multiphysics. This equivalent circuit was subsequently integrated into ATP/EMTP software to simulate leakage currents, yielding satisfactory outcomes. The model was then incorporated into the isolator's equivalent circuit. Results from various simulations indicate that the occurrence of discharge along the dry strip impacts leakage current. Furthermore, the re-initiation of discharge on the contaminated insulator's surface is influenced by the pollutant deposit's conductivity and distribution. Therefore, understanding the pollution level is vital for accurately evaluating and sizing the insulator chain at the installation site.

Endoplasmic reticulum stress produced by Thapsigargin affects the occurrence of spike-wave discharge by modulating unfolded protein response pathways and activating immune responses in a dose-dependent manner

The Endoplasmic Reticulum (ER) is associated with many cellular functions, from post-transcriptional modifications to the proper folding of proteins, and disruption of these functions causes ER stress. Although the relationship between epileptic seizures and ER stress has been reported, the contribution of ER stress pathways to epileptogenesis is still unclear. This study aimed to investigate the possible effects of ER stress-related molecular pathways modulated by mild- and high-dose Thapsigargin (Tg) on absence epileptic activity, CACNA1H and immune responses in WAG/Rij rats. For this purpose, rats were divided into four groups; mild-dose (20 ng) Tg, high-dose (200 ng) Tg, saline, and DMSO and drugs administered intracerebroventriculary. EEG activity was recorded for 1 h and 24 h after drug administration following the baseline recording. In cortex and thalamus tissues, GRP78, ERp57, GAD153 protein changes (Western Blot), Eif2ak3, XBP-1, ATF6, CACNA1H mRNA expressions (RT-PCR), NF-κB and TNF-α levels (ELISA) were measured. Mild-dose-Tg administration resulted in increased spike-wave discharge (SWD) activity at the 24th hour compared to administration of saline, and high-dose-Tg and it also significantly increased the amount of GRP78 protein, the expression of Eif2ak3, XBP-1, and CACNA1H mRNA in the thalamus tissue. In contrast, high-dose-Tg administration suppressed SWD activity and significantly increased XBP-1 and ATF6 mRNA expression in the thalamus, and increased NF-κB and TNF-α levels. In conclusion, our findings indicate that Tg affects SWD occurrence by modulating the unfolded protein response pathway and activating inflammatory processes in a dose-dependent manner.

Sex-Related Differences in Utilization and Outcomes of Extracorporeal Cardio-Pulmonary Resuscitation for Refractory Cardiac Arrest.

Sparse data exist on sex-related differences in extracorporeal cardiopulmonary resuscitation (ECPR) for refractory cardiac arrest (rCA). We explored the role of sex on the utilization and outcomes of ECPR for rCA by retrospective analysis of the Extracorporeal Life Support Organization (ELSO) International Registry. The primary outcome was in-hospital mortality. Exploratory outcomes were discharge disposition and occurrence of any specific extracorporeal membrane oxygenation (ECMO) complications. From 1992 to 2020, a total of 7,460 adults with ECPR were identified: 30.5% women; 69.5% men; 55.9% Whites, 23.7% Asians, 8.9% Blacks, and 3.8% Hispanics. Women's age was 50.4 ± 16.9 years (mean ± standard deviation) and men's 54.7 ± 14.1 ( p < 0.001). Ischemic heart disease occurred in 14.6% women vs. 18.5% men ( p < 0.001). Overall, 28.5% survived at discharge, 30% women vs. 27.8% men ( p = 0.138). In the adjusted analysis, sex was not associated with in-hospital mortality (odds ratio [OR] = 0.93 [confidence interval {CI} = 0.80-1.08]; p = 0.374). Female sex was associated with decreased odds of neurologic, cardiovascular, and renal complications. Despite being younger and having fewer complications during ECMO, women had in-hospital mortality similar to men. Whether these findings are driven by biologic factors or disparities in health care warrants further investigation.

Improvement of Methods and Devices for Multi-Parameter High-Voltage Testing of Dielectric Coatings

Currently, the high voltage testing method is widely used to detect pinholes and porosity defects in dielectric coatings. However, most modern coatings also have requirements for the minimum allowable coating thickness. Conducting tolerance tests on the thickness of dielectric coatings concurrently along with monitoring integrity within a single technological process appears promising. Additionally, mitigating the impact of various interfering parameters is crucial. This paper conducts a theoretical and experimental examination of spark formation processes in both gas and dielectrics. This analysis takes place during the identification of both through and non-through defects in dielectric coatings on conductive substrates. The principles of selecting the test voltage for the investigated dielectric coatings, considering the need to detect both through defects and inadmissible thinning, are theoretically and experimentally justified. It is suggested to utilize a probabilistic approach for evaluating the detectability of the mentioned defects. It is demonstrated that, when the dielectric strength of the coating is known, it is feasible to identify both through and non-through defects in coatings with a calculated probability under a specified test voltage. The conditions of occurrence of partial discharges in the process of testing are investigated, and measures to suppress their influence on the inspection results are proposed. The influence of the substrate surface roughness on the magnitude of the breakdown voltage during testing is considered.

Sensing behavior of modified two-dimensional GeTe monolayer to detect air discharge components: A first-principles study

It is crucial to determine the operating condition of air-insulated equipment by monitoring air discharge components (O3, NO2, CO) to detect any occurrence of partial discharges (PD). Although GeTe is widely applied in gas sensing technology, its performance in selective detection is relatively subpar. This study investigatesthe modification of structures of GeTe monolayers by doping single transition-metal (TM) atom (Fe, Co, Ir, Pt, Pd, and Rh) to enhance its gas adsorption capability and selectivity of different doped GeTe monolayers to gases according to competitive adsorption. Multiple properties such as adsorption energy, charge transfer, charge difference density (CDD), density of states (DOS), occupation function, desorption time, and work function were discussed, indicating that doped GeTe exhibits greater adsorption capabilities. Specifically, Ir-GeTe demonstrates the highest absolute value of adsorption energy for O3 at 2.75 eV, while Co-GeTe exhibits the highest absolute value of adsorption energy for NO2 at 2.13 eV. Furthermore, the analysis of atomic orbital overlap reveals stronger chemical interactions between Ir-GeTe and O3, as well as Co-GeTe and NO2. Considering selectivity and working function, Fe-GeTe emerges as a potential sensing material for detecting NO2. This research offers promising and practical applications for single TM atom-doped GeTe as gas-sensitive materials.