Surface Discharge Research Articles

Plasma Analyzer for the Chinese FY-3E Satellite: In-Orbit Performance and Ground Calibration

The plasma analyzer (PMA) on the Fengyun-3E (FY-3E) meteorological satellite series is a critical sensor of the space environment monitoring package that is capable of the comprehensive in situ detection of the thermal plasma environment and surface discharge effects. In this paper, we conducted a thorough evaluation of the PMA’s performance and reliability through a combination of ground-based laboratory calibration and in-orbit testing. During the ground-based calibration, the PMA underwent assessments for the energy range, field of view (FOV), and measurement accuracy, and obtained the detection accuracy and the geometric factors. During the in-orbit testing, the PMA successfully obtained the typical distribution characteristics of low-energy ions and electrons in orbital space regions, as well as the precipitating particles in the middle and high latitudes of both hemispheres. Notably, the PMA observed an expansion of the particle distribution in the high-latitude regions during a moderate geomagnetic storm. The results from both the ground-based calibration and in-orbit testing demonstrated that the PMA met the requirements for thermal plasma detection, with reliable and scientifically valid in-orbit detection data. These results provide a crucial foundation for studying spatial weather variations, improving the accuracy of space environment forecasts and enhancing disaster detection and monitoring capabilities.

Dielectric exposed on DC-pulsed helium plasma jet: Hollow distribution of the surface electric field

In this study, the electric field distribution on the dielectric surface exposed to helium atmospheric pressure plasma jets with varying operating parameters was investigated. The study considered the effect of applied voltage (7–10 kV), pulse width (0.9–150 μs), and rate (400–2000 sccm), with the investigation based on the Pockels effect. The results suggest that the surface electric field arises from the charge transfer by ionization waves and the expansion of surface discharges. The evolution of the electric field can be segmented into three phases: establishment, maintenance, and dissipation. The gas flow rate determines the mixing “boundary” between helium and air, and consequently affects the shape of the surface electric field distribution. At 400 sccm, the field structure exhibits a solid, elongated shape. At 800–1200 sccm, the field takes on a hollow-ring appearance, and at 1600–2000 sccm, it is presented as two channels. As the applied voltage increases, the surface discharge can be extended further, even surpassing the designated boundary. At 10 kV, the maximum surface electric field and total deposited charge are 5.9 kV/cm and 4.3 nC, respectively. At a fixed frequency of 5 kHz, changing the pulse width affects charging time. The maximum value of the surface electric field and the total deposited charge exhibits an initial increase followed by a decrease. Short pulses (0.9–2 μs) result in incomplete charge transfer, while long pulses (100–150 μs) form a “dark channel” of predominantly negative charge at falling edge of the pulse, which neutralizes the positive charge in the subsequent pulse. A pulse width of 20 μs allows complete charge transfer with less influence from the dark channel.

Biotic-Abiotic Radial-Acicular Crystal Fan Fabrics with Rosickýite at the Angel Springs Tufa-Travertine Deposit in Southern British Columbia

Abstract The tufa-travertine deposit at Angel Springs developed through the interaction of thermal waters with bedrock of the Proterozoic Okanagan Gneiss, which extends along the eastern margin of the Okanagan Valley fault system in south-central British Columbia. This warm spring is proximal to Miocene plateau basalt flows that cut the Okanagan Gneiss bedrock eastward of the Okanagan Valley. The carbonate deposit, which is widely referenced as tufa, consists of a tufa and an overlying travertine. These texturally and petrographically different deposits developed in response to a shift in the groundwater pathway wherein the surface discharge transitioned from multiple vents of the tufa to a single downslope vent pool of the overlying travertine. Lower interval tufa fabrics are characterized by networks of fenestral-type porosity supported by a framework of curvilinear stromatolitic sheets of calcite that resulted from the partial coalescence of sub-horizontal arrays of calcite-encrusted cyanobacteria. These tufa fabrics aligned with the strong stream flow emanating from multiple vents. In contrast, radial crystal fan fabrics of the upper interval travertine developed with the transition from biotic calcite encrustations of upward branching cyanobacteria to the abiotic development of radial crystal fans. Length-long mouldic porosity tubules were occluded as the abiotic sheaf- and fan-shaped crystal growth surfaces expanded radially with rapid degassing. Core areas of the radial crystal arrays coalesced and were partially recrystallized, resulting in spheroidal crystalline fabrics that preserve inclusion-delineated concentric growth surfaces. Syntaxial overgrowths of radially aligned acicular crystals rapidly expanded from these core areas of coalesced calcite, resulting in the formation of abiotic radial-acicular and starburst crystal arrangements. The biotic–abiotic transition resulted in the rapid growth of abiotic crystal fans as the dominant deposition process of the upper interval travertine fabrics, but not in the lower interval tufa fabrics. Activities of sulfate-reducing bacteria in the sulfate-rich thermal water of both intervals resulted in precipitation of rosickýite, the monoclinic polymorph of S, as nanocrystalline globular protuberances on surfaces of calcite crystals. This is the first recorded occurrence of rosickýite in a tufa-travertine deposit and the first recognition of this mineral in Canada.

Исследование течения, создаваемого скользящим разрядом, с помощью методов компьютерного зрения

A quantitative study has been made of the flow with shock waves generated in air by a sliding surface discharge lasting less than one microsecond. The high-speed flow was visualized using the shadowgraph method, the process was recorded at a rate of 124 000 frames/s, the exposure time was 1 μs. The aim of this work is to study the dynamics of the two discontinuities: the cylindrical shock wave and the contact surface generated by the discharge. Each experiment allowed several hundred images to be taken of a short-lived gas-dynamic process lasting up to 1 ms. A YOLOv8 convolutional neural network was trained and used to determine the positions of the discontinuities. A data set of 984 markups was labeled. The model on the mAP50 metric achieved 0.887 and the mAP50-95 was 0.557. The model was used to automatically measure the vertical dimensions of the contact discontinuity. It expands at times up to 0.4 - 0.8 ms to a vertical size of 5 - 11 mm. The x-t plots and the velocities of the cylindrical shock waves were measured. It is shown that up to 1 ms after the discharge, the flow development is due to the blast wind motion behind the shock wave. It is shown that the use of computer vision can significantly speed up the analysis of high-speed flow visualizations and the extraction of quantitative information.

Investigation of electric field distribution on dielectric exposed to DC-pulsed He plasma jet with shielding gas

Atmospheric pressure plasma jets (APPJs) produce reactive species and electric fields for biomedical applications. Gas shields control plasma plume-surrounding gas interactions, regulating reactive species generation and electric field strength. However, the surface electric field distribution is still unclear and needs urgent attention. Here, the electric field distribution on the surface exposed to a helium APPJ with shielding gas is investigated using the Pockels technique. This study considers the influence of the type of shielding gas (ambient air, dry air, nitrogen, oxygen, nitrogen-oxygen mixture) and the flow rate (2000–6000 sccm). The results show that the surface electric field develops in three phases: establishment, maintenance, and dissipation. Both flow rate and oxygen content of the shielding gas significantly influence surface discharge behavior and the maximum electric field value. The analysis suggests that the establishment phase of the electric field results from charge transfer by ionization waves to the dielectric, while the maintenance of the electric field depends on pulse duration. During the dissipation phase, the positive surface charge attracts negatively charged species to the surface (electrons and negative ions), which causes charge neutralization at the surface. The oxygen content in the shielding gas impacts the electric field establishment phase, with a low oxygen content leading to lower photo-ionization rates and, consequently, surface discharges with branching. Shielding gas flow rates affect the amount of shielding gas mixed into the helium channel. Mixing less oxygen into the APPJ increases the electric field strength, as the ionization potential is lower than nitrogen. Excessive oxygen mixing traps more free electrons due to electronegativity, causing fewer ionized collisions and more negative ions in APPJ, ultimately lowering the electric field strength. This study shows that shielding gas type and flow rates can adjust surface charging, aiding in optimizing biomedical APPJ.

Study on surface discharge of nonlinear conductive epoxy resin/SrTiO3 composites in 80–300 K temperature zone

AbstractBisphenol F epoxy resin (EP) is often used in terminal current lead insulation of superconducting equipment because of its good insulation performance, high mechanical strength, good toughness at cryogenic temperatures, and resistance to cold shock and heat shock. However, due to the wide temperature range of 80–300 K and the strong electric field, the EP‐N2 interface is prone to surface flashover, resulting in terminal insulation failure. To improve the reliability of the current lead insulation, non‐linear conductive EP/strontium titanate (SrTiO3) composites were prepared by modification with nano filling. The changes of dielectric, surface discharge, flashover, and trap distribution characteristics of composite materials were studied, and the mechanism of SrTiO3 on the surface flashover of composite materials was analysed. The results show that the conductivity of the composite increases with the rise of SrTiO3 filling content, and the amplitude of improvement is greater under the strong electric field, showing a more significant non‐linearity. The composite has a lower trap energy level and a greater number of shallow traps compared to pure EP, which accelerates surface charge de‐trapping and reduces charge accumulation, effectively enhancing the discharge and surface flashover voltage of the composite.

Interactions Between Flow Fields Induced by Surface Dielectric Barrier Discharge Arrays

This study investigates the flow field induced by a surface dielectric barrier discharge (SDBD) system, known for its efficient pollution remediation of volatile organic compounds (VOCs). We aim to understand the flow dynamics that contribute to the high conversion observed in similar systems using this specific SDBD design. Examining how the surface discharge affects the gas mixing in chemical processes is important for both understanding the fundamentals and for potential industrial applications. Experimental techniques, including schlieren imaging and particle image velocimetry (PIV), applied with high temporal resolution, were used to analyse the flow field. Complementary, fluid simulations are employed to investigate the coupling between streamer and gas dynamics. Results show distinct fluid field behaviours for different electrode configurations, which differ in geometric complexity. The fluid field analysis of the most basic electrode design revealed behaviours commonly observed in actuator studies. The simulation results indicate the local information about the electron density as well as different temporal phases of the fluid flow velocity field containing the development of the experimental found vortex structure, its direction and speed of rotation. The electrode design with mostly parallel grid line structures exhibits confined vortices near the surface. In contrast, an electrode design also used in previous studies, is shown to promote strong gas transport through extended vortex structures, enhancing gas mixing and potentially explaining the high conversion observed.

Detecting surface discharge faults in switchgear by using hybrid model

<span>Switchgear plays a crucial role in power systems, providing protection and control over electrical equipment. However, tracking (surface discharge) can lead to insulation degradation and switchgear failure, necessitating reliable and effective identification of tracking defects. In this paper, we propose a hybrid one-dimension convolutional neural network long short-term memory networks (1D-CNN-LSTM) model as a solution to this problem. Data from both time domain analysis (TDA) and frequency domain analysis (FDA) are utilized for model evaluation. The model achieved error-free accuracy of 100% in both TDA and FDA during the training, validation, and testing phases. The model's performance is further assessed using performance measures and the visualization of accuracy and loss curves. The results show that the hybrid 1D-CNN-LSTM model works well to accurately find and classify surface discharge tracking defects in switchgear. The model offers precise and dependable fault identification, which has the potential to significantly enhance switchgear functionality. By enabling proactive maintenance and timely intervention, the proposed model contributes to the overall reliability and performance of switchgear in power systems. The findings of this research provide valuable insights for the design and implementation of advanced fault detection systems in switchgear applications.</span>

Effect of Extremely Cold Weather and Shrinkage Stress on Interfacial Discharge Between Epoxy and Silicone Rubber in HV Cable Terminations

Gas insulated switchgear (GIS) cable terminations have higher failure rates at low temperatures. In this study, a 110-kV full-size GIS cable termination model is developed to investigate this failure mechanism. The coupling characteristics of the thermal and mechanical stress distributions in the termination are analyzed. A pressure-controlled interfacial discharge experimental setup is established, and the partial discharge characteristics and damage features of tracking are investigated for different interface pressures. At temperatures as low as -40 °C, pressure distortion is observed at the interface between the stress cone and epoxy bushing, such that the interface pressure can drop below 0.1 MPa. The tracking at low interface pressures has a higher growth rate and fewer and finer branches than at high interface pressures. The accumulated damage area tends to develop from the epoxy resin towards the silicone rubber. As the interfacial pressure drops, the characteristics of the partial discharge change from those for internal discharge type to those for coexistence between internal discharge and surface discharge. Finally, a scheme for tracking development and damage under different interface pressures is proposed to explain the failure process for cable termination in an extremely cold environment, which is highly consistent with the characteristics of actual failure.

Parameters of Surface Microwave Discharge Initiated by the Passage of a Gyrotron Microwave Pulse through a Quartz Plate with Embedded Metal Particles

The results of an experimental study of the initiation, development and maintenance of a plasma surface discharge initiated by microwave (microwave) radiation of a gyrotron (75 GHz, 300 kW, 6 ms) in air under normal conditions on the surface of a quartz substrate with metal inclusions are presented. It is shown that the velocity of the propagation of the discharge ionization front reaches 40 m/s, which corresponds to the thermal conduction propagation mechanism. In this case, the maximum calculated gas temperature of the plasma reaches 5500 K, which leads to the sublimation of metal inclusions. For the first time, the plasma parameters of a surface microwave discharge on metal-dielectric targets, which have been used in various aeroplasma and plasma-chemical applications, are presented.

Full cycle, self-consistent, two-dimensional analysis of a packed bed DBD reactor for plasma-assisted splitting: spatiotemporal inhomogeneous, glow to streamer to surface discharge transitions

We investigate the full-cycle operation of a coaxial Packed Bed Dielectric Barrier Discharge (PB-DBD) reactor operating in pure . The reactor is packed with high permittivity dielectric rods and is analyzed with a two-dimensional (2D) self-consistent plasma model. We show that the PB-DBD operation is governed by both glow and volume/surface streamer discharges, forming alternatively and non-uniformly inside the gas volume. The presence and surface charging of the dielectric rods and dielectric layer is crucial for the initiation, propagation, annihilation and afterglow of these microdischarges. Our calculations show maximum electron and densities in the order 1020 m−3, an average discharge power of 353.42 W m−1 in the first cycle, microdischarge peak currents in the order of 50–400 A m−1, total half-cycle plasma charge of around 6 µC m−1, which compare well with experimental findings. Dominant negative ions are found to be . CO molecules and O atoms are mainly formed during the MDs development and the streamer-surface ionization waves. Molecular oxygen () is preferentially formed during the glow, current-decaying and afterglow phase of each microdischarge. The spatially average reduced electric field inside the reactor lies in the 20–100 Td range. Each MD, presents distinct non-uniform and non-repeatable glow and volume/streamer discharges owed to the non-uniform surface charging processes which dictate the complex spatial distribution of produced neutral (and ion) species. These detailed results shed light on crucial, largely non-uniform plasma spatiotemporal characteristics that can help design efficient PB-DBD reactors for splitting and beyond, while emphasizing the important insights obtained by 2D simulations which can not be captured with 0D-global or 1D models.

Runoff hydrographs using Snyder and SCS synthetic unit hydrograph methods: A case study of ungauged watersheds of Imam Turki Bin Abdullah Royal Nature Reserve (ITBA) - Saudi Arabia

Background: The estimation of surface runoff and discharge peak using the Snyder’s model and SCS Dimensionless UH (SCS-DUH) method are one of the best alternatives solutions appropriate for analyzing the hydrologic systems in the ungauged watersheds. These two methods were applied to estimate the discharge peak and design their hydrographs in the drainage basins of Royal Nature Reserve (Imam Turki Bin Abdullah) in Saudi Arabia. - Aims: To estimate the discharge peak by applying Snyder’s model and SCS-DUH method using the morphometric parameters deriving from the SRTM DEM30m and three rainstorms of 40, 50 and 60mm. - Methods: The estimation of discharge peak (Qp) using Snyder’s model was depended on the SRTM DEM30m outputs and the hydrology parameters of the duration (Td) of Unit Hydrograph (UH), time to peak (Tp), time base of the UH (Tb), UH width at 50% and 75% of the peak discharge. However, the estimation of the discharge peak by The SCS-DUH method was computed using the drainage area (A), the direct runoff (Qd) and the time to peak (Tp). The direct runoff was determined by the runoff ratio 0.20 of the unimproved areas, proposed by the Soil Conservation Service (SCS). But, the time to peak was computed using the average of the concentration time obtained from Johnstone-Cross and Dooge models. The hydrographs design was done by the time ratio method recommended by the SCS. - Results: The estimated discharge peak computed by Snyder’s model varies with a maximum of 93.4 to 2092.9 m3/s, an average of 61.1 to 1368.4 m3/s and a minimum of 28.7 to 644.0 m3/s in Al Shuwaiki and Khtal watersheds, respectively. The estimated discharge peak computed by SCS-DUH method was ranged from 21.5 to 482.3 m3/s for the rainstorm of 40mm in Al Suwayki and Khtal, respectively, from 28.5 to 602.9 m3/s for the rainstorm of 50mm and from 34.1 to 723.5 m3/s for the rainstorm of 60mm, in Um Nqy and Khtal, respectively. - Conclusion: The hydrology study of ungauged basins in Royal Nature Reserve (ITBA) shows the great potential of the integrated emplyement of GIS technics and the hydrology models to estimate the discharge peak and design their hydrographs.

Where the water goes: Partitioning surface flow and streambed infiltration in an ephemeral river laboratory experiment

Ephemeral and intermittent flow in dryland streams plays a vital role in supporting delicate ecosystems and recharging groundwater in underlying aquifers. Despite extensive research, accurately predicting surface runoff, streambed water infiltration, and groundwater recharge during ephemeral streamflow events remains challenging due to the complex physical processes involved. Such processes are logistically difficult to observe in the field and should not be assessed through numerical studies alone. To tackle this complexity, we utilized an 8 m long, 0.25 m wide, and 0.6 m deep laboratory flume filled with fine sand as a physical model for event flows along a dry stream. This flume allowed us to measure both streamflow and streambed infiltration volumetrically as the stream wetting front advanced along its length during 8 steady inflow rates. The flume was divided into separate compartments to measure water across the sediment surface (streamflow) and water exiting through the flume’s bottom (groundwater recharge). To validate our physical tests, we compared them with simulated flows in an integrated surface–subsurface hydrological numerical model. The model results exhibited good agreement with the observed stream and groundwater dynamics. Through a parametric numerical investigation, we identified that hydraulic conductivity significantly controlled the rate of surface infiltration and the advancement of the stream wetting front. Interestingly, we found a linear relationship between surface discharge and stream wetting front location, as well as groundwater recharge, under steady-state conditions, in line with the governing equations. However, our simulations of variable streambed heterogeneity and elevation unveiled the crucial influence of these factors in determining the timing of downstream flow progression. This insight is essential for establishing ecological connectivity along non-perennial rivers and has significant implications for delivering environmental flows in arid regions where ephemeral rivers are prevalent. Our study underscores the value of flume experiments in elucidating the transient physical processes during surface water and groundwater interactions in intermittent streams. By employing a combination of physical modelling and numerical simulations, we advance our understanding of these vital hydrological interactions, contributing to sustainable water management practices in semi-arid and arid environments.

Heat Transfer and Pressure Loss Correlations for Leading Edge, Jet Impingement Using Racetrack-Shaped Jets With Filleted Edges

Abstract This paper presents an experimental investigation of heat transfer and pressure loss for leading-edge jet impingement using racetrack-shaped jets. The majority of literature for gas turbine cooling applications considers jet impingement using square or sharp-edged orifices. However, the edge of the jet orifices generally has some degree of filleting (or rounding) along the edges, due to casting the airfoils or material wear due to long-term operation. Engineers need data under realistic engine configurations to improve the utilization of coolant while adequately protecting the airfoil. The current experimental study is a parametric investigation of heat transfer and pressure loss for leading-edge jet impingement, where the effects of jet Reynolds number (Re = 10,000–100,000), jet–to–jet spacing (s/d = 2–8), jet–to–target surface spacing (z/d = 2–4), surface curvature (D/d = 2.67–5.33), and jet fillet–to–jet plate thickness (r/l = 0.16–0.5) are each considered. The edge rounding at both the inlet and outlet of the jet plate yields reduced heat transfer compared to the square-edged jets. However, the fillets significantly improve the discharge coefficients associated with the racetrack-shaped orifices. With the extensive testing completed in this study, design correlations have been developed to predict the surface Nusselt number and discharge coefficients, with 10% and 19% deviation from experimental results, respectively. Engine designers can predict the level of heat transfer and pressure loss for leading-edge jet impingement using these correlations.

Analysis of The Itsg-Grace Daily Models in The Determination of Polar Motion Excitation Function

ABSTRACT The main aim of this study is to evaluate the usefulness of Institute of Geodesy at Graz University of Technology (ITSG) daily gravity field models in the determination of hydrological angular momentum (HAM) at nonseasonal time scales. We compared the equatorial components (χ1 and χ2) of HAM calculated with the ITSG daily gravity field models (ITSG-Gravity Recovery and Climate Experiment [ITSG-GRACE] 2016 and ITSG-GRACE 2018) with HAM and sea-level angular momentum (SLAM) from hydrological land surface discharge model (LSDM) and the hydrological signal in the polar motion excitation (known as geodetic residuals [GAO]). Data from ITSG have a daily temporal resolution and allow us to determine oscillations with higher frequencies than the more commonly used monthly data. We limited our study to the period between 2004 and 2011 because of the gaps in GRACE observations before and after this period. We evaluated HAM obtained from ITSG GRACE models in spectral and time domains and determined the amplitude spectra of the analyzed series in the spectral range from 2 to 120 days. Our analyses confirm the existence of a sub-monthly signal in the HAM series determined from ITSG daily data. We observed a similar signal in LSDM-based HAM, but with notably weaker amplitudes. We also observed common peaks around 14 days in the amplitude spectra for the GAO- and ITSG-based series, which may be related to the Earth’s tides. ITSG daily gravity field models can be useful to determine the equatorial components of HAM at nonseasonal time scales.

A novel robust SCR with high holding voltage for on-chip ESD protection of industry-level bus

In an industry-level bus, strong electrostatic interference seriously threatens the reliability of chips. However, the holding voltage (Vh) and robustness of traditional silicon-controlled rectifier (SCR) cannot meet the electrostatic discharge (ESD) window of industry-level applications. To better cope with extreme environments, this paper proposes a novel SCR with high robustness and latch-up immunity for on-chip ESD protection of the industry-level RS485 bus. By incorporating a surface current diverting path into the traditional SCR, the ESD characteristics of the proposed device are significantly improved. Through two-dimensional device simulation, the ESD characteristics of traditional SCR, proposed P-Well Floating SCR (PFSCR) and proposed P-Well Grounded SCR (PGSCR) are compared, with a focus on exploring the role of surface discharge path. Three types of SCR are realized based on the 0.18 μm BCD process. The transmission line pulse (TLP) test results show that PGSCR (13.64 V) has a higher Vh and higher robustness than traditional SCR (2.13 V) and PFSCR (4.39 V). In addition, the trigger voltage (Vt1:22.9 V) and failure current (It2:18.49A) of the PGSCR fully meet the ESD window of the target chip.

(Invited) Visualization of Charge Density Distribution in Parallel-Plate Dielectric Barrier Discharge Under Atmospheric-Pressure Air

Dielectric barrier discharge (DBD) is one of the atmospheric nonequilibrium plasma and is typically driven by sinusoidal or pulse voltage with electrodes that dielectric is inserted. DBD has been used in some industries such as plasma medicine and material processing. However, the fundamental process of DBD has not been elucidated yet. When a parallel plate DBD is driven by sinusoidal voltage under atmospheric pressure, numerous filamentary discharges called microdischarges (MDs) are observed. The surface charge deposited on the dielectric after the discharge plays a major role in the behavior of these MDs. As the MD develops during the gap and reaches the dielectric surface, a surface discharge occurs and deposits the charge on the dielectric surface.We performed dielectric surface charge measurements using Bi4Ge3O12, a Pockels crystal, in a short-gap, parallel-plate DBD of 0.5 and 0.3 mm driven by a sinusoidal high voltage. The high-speed camera enabled measurement of the spatio-temporal distribution of surface charge and estimation of the net electric field and the characteristics of microdischarges (MDs).The net electric field strength in the gap was estimated from the measurement results. The axial reduced electric field strength generated by the surface charge was found to be equivalent to 50-60% of the peak value of the applied electric field with all the voltage amplitude and gap length in this study, and the gap electric field after discharge was suppressed to less than 100 Td. Such a strong field keeps the MDs in a nonequilibrium plasma and also prevents re-discharge in the same position at the half cycle. On the other hand, the lateral electric field strength generated by the surface charge is largely characterized by the charge distribution—i.e., the voltage amplitude, gap length, and charge polarity—as mentioned above. Higher amplitude of applied voltage leads to an increase in the area of high lateral electric field strength above 100 Td. Compared to the gap length of 0.5 mm, the lateral electric field weakened, while the axial electric field generated by the surface charge was stronger in the gap length of 0.3 mm. As for the relationship between the charge polarity and the lateral electric field, the lateral field at the anodic dielectric, which the negative charge is deposited on, is dominant in the region of less than 100 Td. Meanwhile, on the cathodic dielectric, which the positive charge is deposited on, the area of above 100 Td is larger. That is, the strong lateral electric field can be observed near the cathodic dielectric, rather than the anodic dielectric. Thus, different chemical reactions may occur in the vicinity of the anodic and cathodic dielectrics, respectively, because of the difference in the drifting charged particles and the lateral field strength.

Mapping of heterogeneity on groundwater level and potential zones along expeditiously urbanizing tropical coastal regions

The study of coastal groundwater potential is critical as freshwater availability is under tremendous stress due to increased coastal region development and noticeable monsoonal changing patterns over time. In addition to these factors, Odisha's coastal region has a larger drainage network in low-lying plains, which reduces freshwater recharge by increasing surface discharge. To sustain freshwater usage, the demarcation of the Groundwater potential zone (GWPZ) was done using Geographic Information System (GIS), Analytical Hierarchy Process (AHP), and Multi Influence Factor (MIF). Factors such as geomorphology, geology, land use/land cover, rainfall, lineament density, drainage density, elevation, slope, and soil were considered to accurately predict GWPZ. The AHP technique was used to construct a pairwise comparison matrix (PCM) and assign weights to each thematic layer, whereas the MIF method computes a recommended score for each layer based on the sum of the major and minor effect weights. The findings demonstrate that a significant portion of the study area falls into the "good" GWPZ (∼ 83% for both methods) category, indicating that the aquifer's storage is adequate. The output was validated by the Receiver operating curve (ROC) and groundwater prospects data. The ROC findings showed that the Area under curve (AUC) was 81% and 80.1% for AHP and MIF, respectively. This outcome signifies moderate to high precision indicating that the model could make accurate positive predictions. Analysis of pre-monsoon and post-monsoon water levels reveals spatial variations, with lower water levels indicating higher potential. Water levels in low-lying plains with high groundwater potential zones (GWPZ) are declining due to coastal erosion, sediment accumulation, limited infiltration, and increasing seawater intrusion. Continued groundwater abstraction may aggravate seawater intrusion despite favorable geological conditions. This study would be advantageous for coastal region decision-making involving water resource management and planning for sustainable development.

Advanced Diagnostic Approach for High-Voltage Insulators: Analyzing Partial Discharges through Zero-Crossing Rate and Fundamental Frequency Estimation of Acoustic Raw Data

Acoustic inspection is a valuable technique that can detect early stage defects in equipment, thereby facilitating predictive maintenance. In recent times, ultrasonic sensors have made detecting partial discharges through acoustic sensing increasingly feasible. However, interpreting the acoustic signals can pose challenges, as it requires extensive expertise and knowledge of equipment configuration. To address this issue, a technique based on zero-crossing rate and fundamental frequency estimation has been proposed to standardize insulator diagnosis. In an experiment involving a database of 72 raw acoustic signals with frequencies ranging from 0 to 128 kHz, various types of pollution and defects were introduced to a chain of insulators. By employing the proposed technique, the occurrence of partial discharges can be detected and classified according to type, such as corona or surface discharges. This advanced approach to diagnosis simplifies the process while providing valuable insights into the severity of observed phenomena in the field.

Sediment modeling using laboratory-scale rainfall simulator and laser precipitation monitor

The characterization of a rainfall simulator provides an excellent opportunity to study the potential of soil erosivity without waiting for natural rain. But, precise instrumentation is required to estimate the parameters, which is seldom available. To overcome this problem, the empirical and conceptual relationships obtained through physically-based modeling help to correlate the rain parameters contributing to soil erosion. The present laboratory study used five pressurized nozzles of different capacities and a Laser Precipitation Monitor (LPM) to generate different rain intensities (21.0–79.0 mm h−1) and to register drop size distribution, respectively. The sediment transportation induced by rain and runoff was measured with an erosion flume of 2.50 × 1.25 × 0.56 m with an adjustable longitudinal slope. The spatial uniformity, drop size distribution, drop velocity, and kinetic energy were used to evaluate the simulator's performance. The different rain erosivity parameters were correlated and tested statistically using linear and non-linear regression analysis. The rain simulation experiments of different intensities at different pressure ranges were performed on flat, 5, 10, and 15% slopes of the erosion flume to evaluate rain characteristics and record the surface runoff and sediment yield. The median drop sizes produced during the simulator ranged from 0.38 to 2.11 mm, coinciding with natural rain. The empirical relationships were developed to correlate surface discharge and sediment yield with rain intensity by optimizing the parameters for further study of experimental field plots of different slopes. The observed and estimated rain erosivity parameters showed a significant relationship (R2 = 0.75 to 0.93; P < 0.001) in multiple regression analysis, and the metrics used to test the developed regression equations showed lower MAE, MSE, and RMSE errors indicating the adequacy of the relationships. The results indicated that the simulator helps to understand the complex task of soil erosion with hydrologic and geomorphic processes in laboratory experimentation with sufficient accuracy in measuring sediment transport events.