High Voltage Electrical Discharges Research Articles

Epilepsy secondary to brain injury by electrocution: A case report

Introduction: According to the Yearbook of Accidents of Electrical Origin for the year 2022, 853 accidents due to electric shock were reported in Brazil, of which 592 died, a reduction of 12.2% in mortality compared to the previous year. Three conditions elucidate trauma switches caused by the passage of electric current, the regulatory alterations by the passage of electric current, the conversion of electrical energy into thermal, known as the Joule effect, and muscle damage by the electrical stimulus of exacerbated contractions. Case Report: A 51-year-old male patient was followed up on an outpatient basis due to a nervous breakdown caused by accident with a high-voltage electrical discharge 15 years ago. After the event, he evolved with conduction aphasia, homonymous hemianopia on the right, hypoesthesia on the right side of the body, dysmetria on the right upper limb, and epileptic seizures of focal onset, evolving into tonic-clonic seizures. For seizure control, carbamazepine 200 mg 3 times a day was administered, with complete seizure control since then. Conclusion: Therefore, it is important to emphasize that the damage caused by electrocution to the central nervous system (CNS) is varied. Still, due to the patient’s clinical presentation, his neuroimaging findings, and his history, this is epilepsy secondary to electrocution. Encephalomalacia demonstrates a large scar in the brain tissue, and its control of seizure episodes with the adopted pharmacotherapy also corroborates.

A generalized physical principle of development of plasma channel of a high-voltage pulse spark discharge in a dielectric

Goal. Development of the generalized physical principle of development of plasma channel of a high-voltage electrical pulse spark discharge in the homogeneous dielectric of the different aggregate state. Methodology. Basis of physical optics, theoretical electrical engineering, electrophysics bases of technique of high-voltage and large pulse currents, bases of high-voltage pulse technique and measuring technique. Results. Development of physical principle of development of plasma channel of an electric pulse spark discharge is executed in a homogeneous gas dielectric on the applied example of the use in calculations and experiments of the double-electrode discharge system (DEDS) with a long air interval, testing action of standard interconnect аperiodic pulse of high-voltage of temporal shape of Tm/Тd≈200 μs/1990 μs of positive polarity. The generalized formula is got for the calculation of total length of lc of the real way of development of an pulse spark discharge in an air dielectric, which allowed to formulate the offered physical principle in the following kind: «The plasma channel of an pulse spark discharge in a gas dielectric spreads from one of its points to other after a way length of lc, providing the least falling on it of electric voltage of Uc». It is shown that this principle in the first approaching can be applied and to the homogeneous liquid and hard dielectrics. Comparison of the developed physical principle of distribution of plasma channel of an electrical spark discharge is executed in a dielectrical environment with fundamental Fermat physical principle (a law) for distribution of light in an optically transparent environment, which specifies on mathematical likeness and closeness on destiny of these physical principles. Calculation estimations of falling of electric voltage of Uc on total length of lc of the real zigzag way of development in the air dielectric of DEDS a «edge-plane» with the least length of its discharge interval of lmin=1,5 m is presented, that a value Uc does not exceed 9 % from the experimental level of aggressive voltage of Umd≈611,6 кV in this DEDS for the аperiodic pulse of voltage of Tm/Тd≈200 μs/1990 μs. It is set that the estimated time of td advancement of leader channel of electric pulse discharge in air DEDS (lmin=1,5 m) on its real way total length of lc≈1,53 m makes td≈15,3 μs, and experimental duration of cut of Tdc of the indicated аperiodic impulse of voltage utilized in experiments, characterizing time of short circuit by the plasma channel of discharge of air interval in DEDS, appears equal Тdc≈td≈17 μs. Originality. The generalized physical principle of development of plasma channel of a high-voltage electrical pulse spark discharge is first developed in the homogeneous dielectric of the different aggregate state. Practical value. Application in electrical engineering practice and high-voltage pulse technique of the offered principle of distribution in the dielectrics of plasma channel of an pulse spark discharge will allow to develop both new and to perfect the existent methods of computer design of electro-discharge processes in the gas, liquid and hard insulation of different high-voltage electrical power engineering and electrophysics devices, directed on the increase of reliability of their operation.

Microstructure and Phase Composition of Ti-Al-C Materials Obtained by High Voltage Electrical Discharge/Spark Plasma Sintering.

Titanium-based composite materials arouse interest in fields like aerospace, transportation, medicine, and other applications. This research project presents the analysis of phase composition of sintered Ti-Al-C composite materials under high voltage electrical discharge. The new technology, described in the previous work of the authors, allows to synthesise the composites containing various intermetallics, carbides, and nanostructures. The samples of Ti-Al-C powder composites were tested by SEM, Raman spectroscopy, and XRD. It was determined that the treatment of the powder by high voltage electrical discharge (HVED) and further sintering at high temperatures using the spark plasma sintering (SPS) method encouraged the formation of the intermetallic reinforcing phases, carbides, and different nanocarbon structures like graphene and fullerenes, as well as pure graphite. Intermetallic phases and nanocarbon structures improved the mechanical and physical properties of the composites. By using the experimental methods mentioned above, the phase composition of Ti-Al-C powder composites obtained at different sintering temperatures was determined. It was revealed that new composite materials produced by HVED and further SPS were rich with carbides, intermetallics, and MAX phases. Therefore, the carbon nanostructures (graphene and graphite) were detected existing in the structure of the produced new Ti-Al-C composite material. All these reinforcing particles improved the microstructure and the mechanical properties of the composites, as was proved in the previous research by the authors and by the different scientific resources. This project is a pilot experimental work, therefore not all peaks of Raman and XRD were detected; they will be analysed in future works.

Recent advances incombined Avant-garde technologies (thermal-thermal, non-thermal-non-thermal, and thermal-non-thermal matrix) to extract polyphenols from agro byproducts.

Because food byproducts (waste) are rich in phytoconstituents, valorizing them is crucial for global food security. However, conventional extraction (CE), including decoction, maceration, Soxhlet, etc., for agro byproducts' polyphenol extraction are time-consuming and rely significantly on vast volumes of potentially aggressive solvents. Hence, Avantgarde extraction technologies, including non-thermal (high hydrostatic pressure (HHPE), pulsed-electric field (PEF), high voltage electrical discharges (HVED), etc.) and thermal extraction (supercritical fluid (SCF), subcritical water extraction (SWE), microwave-assisted extraction (MAE), etc.), as well as their thermal combinations (SCF-PLE, SCCO2-SWE, SCCO2-MAE, etc.), non-thermal combinations (HHPE + UAE, PEF + UAE, HVED + UAE, etc.) and combined thermalnon-thermal (MAE-UAE, etc.) are increasingly replacing CE. However, a review of combined Avant-garde extraction escalation technologies (non-thermal/thermal extraction matrix) for extracting polyphenols from agro-byproducts is limited. Hence, this manuscript reviewed Avant-garde extraction technologies (non-thermal/thermal extraction matrix) for extracting phenolics from agro-byproducts in the last 5 years. The key factors affecting polyphenols' extraction from the byproduct, the recent applications of Avant-garde technologies, and their principle were reviewed using databases from Web of Science and Lens.org. The results demonstrated that combined Avant-garde extraction escalation technologies increase extractability, resulting in polyphenols with higher extraction rates, fewer contaminants, and preservation of thermosensitive components. Therefore, combined Avant-garde extraction technologies should be explored over the next five years. Implementing an integrated process and the strategic sequencing of diverse Avant-garde extraction technologies are important. Thus, further investigation is required to explore the sequencing process and its potential impact on the extraction of phenolics from agro-byproducts.

Experimental study on the dynamics of a spark bubble near the top of a cylinder and associated annular secondary cavitation bubbles

This paper presents an experimental study focused on the annular secondary cavitation caused by the interaction between a high-voltage spark bubble and a cylinder. A 2000 V high-voltage underwater electric discharge was used to create the bubble, which reached a maximum diameter of approximately 31 mm. High-speed photography was employed to capture the behavior of the spark bubble and the induced secondary cavitation bubbles. The formation and evolution of the annular secondary cavitation bubbles near the cylinder's edge were captured and analyzed. The study classified the morphology of the annular secondary cavitation bubbles into three different types based on various bubble distances and cylinder diameters. Notably, unique bubble morphologies, such as the terraced bubble shape, were identified, resulting from the coupling between the spark bubble, the annular secondary cavitation bubble, and the cylinder. The interaction between the annular secondary cavitation bubble and the spark bubble, including coalescence, and the resulting effects on bubble shape and period were investigated. The changes of secondary cavitation bubbles are compared when the cylinder has different chamfer angles. Moreover, the study examined the dynamic characteristics of the bubbles, including their shape evolution, jetting behavior, period length, and pressure pulses upon collapse, at various distances from the top-surface of cylinders with different diameters. The experiment also introduced flow visualization with dye into spark bubble experiments for the first time to trace the vortex around the annular secondary bubble. Additionally, the transparency of bubbles in the images was improved through multi-source lighting techniques.

Effect of high-voltage electrical discharge (HVED) at high frequency on vacuum freeze-drying time and physicochemical properties of blueberries

Vacuum freeze-drying provides high-quality food products. However, it requires long operating times and high energy consumption. High voltage electrical discharge (HVED) is an emerging technology that could enhance freeze-drying rates and final product quality. This study aimed to evaluate the effect of HVED at high frequency (200 kHz) on freeze-drying kinetics of blueberries (effective moisture diffusivity, drying times) and the physicochemical properties of the resulting freeze-dried fruits. Blueberries were pretreated at different electric field strengths (10, 20, and 30 kV/cm) and operational times (10, 20, and 30 s) and freeze-dried until constant weight. The HVED treatment at 30 kV/cm and 30 s exhibited the best moisture diffusivity values and reduced drying time by at least 30% compared with untreated samples. Samples treated with HVED and freeze-dried preserved their shape and prevented shrinkage. Applying HVED as a pretreatment electrotechnology can help improve the efficiency of freeze-drying and the quality of dried food products.

Experimental Studies of Hydrodynamic and Energy Characteristics of a High-Voltage Electrochemical Explosion in Limited Liquid Volumes

In this paper, the dependence of the charging voltage, stored electrical energy, and the mass of the combusted exothermic mixture on electrical, energy and hydrodynamic characteristics of a high-voltage electrochemical explosion (HVEE) in limited volumes of liquid on is experimentally studied. A comparison with other methods of initiating an electric discharge under similar conditions was made. The results established that the HVEE makes it possible to carry out a high-voltage electric discharge with low energy losses (less than 9%) and to realize an electrical breakdown mode close to aperiodic. It has been found that HVEE can generate pressure waves with an amplitude up to 37% and a pulse up to 45% larger (at a charging voltage of 25 kV or higher) than that of an electric explosion of an initiating metallic conductor of optimum length under the same initial conditions. It was found that an increase in the charging voltage leads to an increase in the amplitude and pulse of the generated pressure wave along a linear dependence. A compre-hensive analysis of the dependences of the energy and hydrodynamic characteristics showed that the main influence on the formation of the pressure wave pulse during the HVEE is provided by both the stored electrical energy and the interconnection between the electrical parameters of the discharge circuit and the mass of the burning exothermic mixture, which determines the shape of the discharge characteristics.

Electric performance of hybrid busbar joints under service and high voltage conditions

This paper is focused on hybrid busbar joints with a twofold objective of understanding the differences in electrical resistance under service conditions and evaluating their performance when subjected to hazardous high voltages. Three different types of joints fabricated by conventional bolting, friction stir spot welding and injection lap riveting are selected and two different experimental setups are used to allow the hybrid busbars to be tested up to high voltage electrical discharges of 30 kV. The work is an enhancement of previous experimental and numerical investigations of the authors in the field with results showing no signs of damage or catastrophic failure when the different types of busbars are subjected to high voltage electrical discharges. Results also confirm the good overall performance and advantages of injection lap riveted hybrid busbar joints against bolted and friction stir spot welded.

Investigation of the Microstructure of Sintered Ti-Al-C Composite Powder Materials under High-Voltage Electrical Discharge.

Dispersion-hardened materials based on TiC-AlnCn are alloys with high heat resistance, strength, and durability that can be used in aircraft and rocket technology as a hard lubricant. The titanium-rich composites of the Ti-Al-C system were synthesized via the spark plasma sintering process. Composite powder with 85% of Ti, 15% of Al, and MAX-phases was processed using high-voltage electrical discharge in kerosene at a specific energy of 25 MJ kg-1 to obtain nanosized particles. This method allows us to analyze the most efficient, energy saving, and less waste-generating technological processes producing materials with improved mechanical and physical properties. An Innova test indentation machine was used to determine the hardness of the synthesized composites. The microhardness of Ti-Al-C system samples was determined as approximately 500-600 HV. Scanning electron microscopy and energy-dispersive X-ray spectroscopy were performed to identify the hard titanium matrix reinforced by intermetallic phases and the clusters of carbides. Three types of reinforcing phases were detected existing in the composites-TiC, Al4C3, and Al3Ti, as well as a matrix consisting of α- and β-titanium. The lattice parameters of all phases detected in the composites were calculated using Rietveld analysis. It was determined that by increasing the temperature of sintering, the amount of aluminum and carbon increases in the carbides and intermetallic phases, while the amount of titanium decreases.

Application of radiation technologies, increase of catalysts surface activity

The catalyst surface was processed in the high-voltage electrical discharge device in oxygen environment. Continuous active oxide centers formed on the surface and complete filling of the surface with oxygen occur, and its thermo-physical properties, thermo-luminescence curves, scanning electron microscope and ESR spectrometers were studied. It was determined that the activity of the catalyst at values of the absorbed dose [Formula: see text][Formula: see text]kGy is many times higher than that of conventional catalysts. Thus, due to the sorption volume of the surface, the volume of the product formed in the liquid phase increases by 1.6 times.

Alternative methods for RuBisCO extraction from sugar beet waste: A comparative approach of ultrasound and high voltage electrical discharge

Ultrasound (US) and high voltage electric discharge (HVED) with water as a green solvent represent promising novel non-thermal techniques for protein extraction from sugar beet (Beta vulgaris subsp. vulgaris var. altissima) leaves. Compared to HVED, US proved to be a better alternative method for total soluble protein extraction with the aim of obtaining high yield of ribulose-1,5-bisphosphate carboxylase-oxygenase enzyme (RuBisCO). Regardless of the solvent temperature, the highest protein yields were observed at 100% amplitude and 9 min treatment time (84.60 ± 3.98 mg/gd.m. with cold and 96.75 ± 4.30 mg/gd.m. with room temperature deionized water). US treatments at 75% amplitude and 9 min treatment time showed the highest abundance of RuBisCO obtained by immunoblotting assay. The highest protein yields recorded among HVED-treated samples were observed at a voltage of 20 kV and a treatment time of 3 min, disregarding the used gas (33.33 ± 1.06 mg/gd.m. with argon and 34.89 ± 1.59 mg/gd.m. with nitrogen as injected gas), while the highest abundance of the RuBisCO among HVED-treated samples was noticed at 25 kV voltage and 3 min treatment time. By optimizing the US and HVED parameters, it is possible to affect the solubility and improve the isolation of RuBisCO, which could then be purified and implemented into new or already existing functional products.

Synergy Effect during Water Treatment by Electric Discharge and Chlorination

Water treatment, such as disinfection, is an integral stage of its use for human life. The use of plasma technology with high-voltage electric discharge in a liquid for obtaining a bactericidal effect is discussed. It has been experimentally shown that among the factors accompanying a high-voltage electric discharge in a liquid and affecting the viability of bacteria, cavitation is the main one. Simultaneous use of electric discharge in the special cavitation mode and oxidizing agents makes it possible to achieve stable disinfection of water. At the same time, bactericidal doses of the oxidizing agent are reduced by a factor of 10 relative to existing standards, and the energy costs for electric discharge exposure, enhanced by small doses of an oxidizing agent, are reduced by 6 times compared to the costs of disinfection by only an electric discharge.

Development of Determination Methodology of Electrical Conductivity of Titanium-based Composites

The Ti-based metal matrix composite samples are novel, fabricated by using high voltage electric discharge and spark plasma sintering processes. They have potential usage in the aviation industry. A research that allowed measuring an electrical conductivity of Ti-based composites was performed. A collinear four-point probe method was chosen for measurement of electrical conductivity. Needle-like probes were used to contact the tested sample. Other aspects of the measurement setup are discussed and selected according to relevant literature. A simulation was performed using COMSOL software to validate the measurement method. Furthermore, a simulation performed for contact force of the probes was performed. A 3D model of the measurement tool was created and designed. The measurement setup was tested and validated by using a copper sample. electrical resistance of Ti-based composite samples was measured, and electrical conductivity was calculated. Furthermore, samples were measured at different temperatures and resistivity dependence to temperature was presented. Experimental results are compared to similar research results.

Encapsulation of Rosemary Extracts using High Voltage Electrical Discharge in Calcium Alginate/Zein/Hydroxypropyl Methylcellulose Microparticles.

The increased demand for functional food with added health benefits is directing industrial procedures toward more sustainable production of naturally added bioactive compounds. The objective of this research was to investigate the potential of bioactive compounds from rosemary extract obtained using high-voltage electrical discharge as a green extraction method, for microencapsulation as a protective method for future application in functional food. Four types of microparticles were made via the ionic gelation method using alginate (Alg), zein (Z), and hydroxypropyl methylcellulose (HPMC) biopolymers and were analyzed considering the physicochemical properties. The diameter of dry microparticles ranged from 651.29 to 1087.37 μm. The shape and morphology analysis of microparticles showed that the obtained microparticles were quite spherical with a granular surface. The high encapsulation efficiency was obtained with a loading capacity of polyphenols up to 11.31 ± 1.47 mg GAE/g (Alg/Z microparticles). The microencapsulation method showed protective effects for rosemary polyphenols against pH changes during digestion. Specifically, the addition of both zein and HPMC to calcium-alginate resulted in microparticles with a prolonged release for better availability of polyphenols in the intestine. This research background indicates that the release of rosemary extract is highly dependent on the initial biopolymer composition with high potential for further functional food applications.

Synthesis of Combined Energy Sources Based on High-Voltage Electrochemical Explosion

An algorithm of the stage-by-stage synthesis of combined energy sources based on a high-voltage electrochemical explosion (HVECHE) was developed. The algorithm provides the necessary space-time force and energy impact on processing objects to perform specified technological operations. At the first stage, the synthesis of an energy source based on a high-voltage electric discharge in condensed media was done by means of solving inverse synthesis problems and, as a result, determining the required total energy with its subsequent optimal separation into electrical and chemical components. Experimental studies of the dependence functions of the force impact on the processing object on the energy characteristics of the HVECHE were carried out. Based on those studies, the criteria for the optimal proportion between the electrical and chemical components of the required total energy were determined. An example of a specific use of the developed algorithm for the synthesis of a combined energy source based on the HVECHE was given, which confirms the possibility to use this algorithm for engineering calculations.

Erosion of an Electrode during a High-Voltage Electric Discharge in a Liquid

Erosion of an Electrode during a High-Voltage Electric Discharge in a Liquid

Extraction of Mycosporine-like Amino Acids and Proteins from the Agarophyte Gelidium corneum Using Pulsed Power Techniques

Gelidium corneum (syn. sesquipedale) is an industrially and ecologically important species of red alga used for the production of high-quality agar. However, the species is also of growing interest for the production of other valuable compounds, such as mycosporine-like amino acids (MAAs), with potential cosmeceutical and biomedical applications. Novel methods using two pulsed power techniques, high-voltage electrical discharges (HVED) and pulsed electrical fields (PEF), were evaluated for efficacy of MAA extraction. Algal suspensions were prepared at two ratios (1:20 and 1:40 w:v). Four different extraction protocols were compared: (i) high-voltage electrical discharges, (ii) pulsed electric fields, (iii) maceration at room temperature, and (iv) maceration at 50 °C. The algae were treated in three states: freshly harvested, dried, and powdered. HVED and PEF treatments were effective when performed on fresh algae, and in particular the HVED treatment resulted in yields of MAAs twenty times higher than the control: 0.81 ± 0.05 mg/gDry Weight (DW) vs. 0.037 ± 0.002 mg/gDW. This effect was not observed to the same extent when the algae were dried or powdered, although HVED remained the most selective method overall.

MODELING THE DYNAMICS OF HEAT AND MASS TRANSFER PROCESSES IN A TUBULAR HEAT EXCHANGER UNDER PULSED INFLUENCES

The paper discusses the results of experimental studies of the influence of the degree of inhomogeneity of a liquid flow on the dynamics of heat and mass transfer processes under pulsed impacts. High-voltage electric discharges in a liquid medium were used as impulse actions, through which an electro-hydraulic effect is realized, accompanied by the appearance of shock waves. The dynamics ofthe occurring nonlinear, rapidly changing heat and mass transfer processes at high hydraulic pressures cannot be described using differential equations. The simulation was carried out on the basis of the method of group consideration of arguments, the advantage of which is the construction of polynomial dependencies using a small amount of experimental data. The results of constructing polynomial dependences made it possible to reveal the synergistic effect of the influence of flow parameters on the dynamics of the impulse pressure amplitude and the intensity of heat transfer.

Effects of High Voltage Electrical Discharge (HVED) on Endogenous Hormone and Polyphenol Profile in Wheat.

High voltage electrical discharge (HVED) is an eco-friendly low-cost method based on the creation of plasma-activated water (PAW) through the release of electrical discharge in water which results in the formation of reactive particles. Recent studies have reported that such novel plasma technologies promote germination and growth but their hormonal and metabolic background is still not known. In the present work, the HVED-induced hormonal and metabolic changes were studied during the germination of wheat seedlings. Hormonal changes including abscisic acid (ABA), gibberellic acids (GAs), indol acetic acid (IAA) and jasmonic acid (JA) and the polyphenol responses were detected in the early (2nd day) and late (5th day) germination phases of wheat as well as their redistribution in shoot and root. HVED treatment significantly stimulated germination and growth both in the shoot and root. The root early response to HVED involved the upregulation of ABA and increased phaseic and ferulic acid content, while the active form of gibberellic acid (GA1) was downregulated. In the later phase (5th day of germination), HVED had a stimulatory effect on the production of benzoic and salicylic acid. The shoot showed a different response: HVED induced the synthesis of JA_Le_Ile, an active form of JA, and provoked the biosynthesis of cinnamic, p-coumaric and caffeic acid in both phases of germination. Surprisingly, in 2-day-old shoots, HVED decreased the GA20 levels, being intermediate in the synthesis of bioactive gibberellins. These HVED-provoked metabolic changes indicated a stress-related response that could contribute to germination in wheat.

The use of machine learning methods to predict the processes and results of high-voltage electric discharge processing of titanium powder in kerosene with the implementation of volume-distributed multi-spark discharge

The possibility of using machine learning methods to predict the results of high-voltage electric discharge treatment of titanium powder in a hydrocarbon liquid is studied. Distribution surfaces for the average particle diameter of Titanium powder. The amount of Titanium carbide formed during processing, and the number of spherical particles of titanium powder depending on the interelectrode gap and the number of pulses, when using volume-distributed multi-spark discharge and with Titanium powder concentration in kerosene of 0.07 kg / dm3, pulse repetition frequency 0.3 Hz and the energy of single discharge of 1 kJ, were obtained.