Articoli di riviste: "High voltage electrical discharge (HVED)"

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Gryszkin, Artur, Marijana Grec, Đurđica Ačkar, Tomasz Zięba, Antun Jozinović, Drago Šubarić, Borislav Miličević, Marijana Blažić e Jurislav Babić. "Phosphorylation of Maize Starch Enhanced with High-Voltage Electrical Discharge (HVED) Instead of Thermal Treatment". Polymers 13, n. 19 (23 settembre 2021): 3231. http://dx.doi.org/10.3390/polym13193231.

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The aim of this research was to explore the use of a high-voltage electrical treatment (HVED) as a substitute for heating during the phosphorylation of maize starch. Starch was treated with HVED, phosphorylated with Na2HPO4 or Na5P3O10 with and without thermal treatment and phosphorylated in combination with HVED prior to and after the chemical modification. When starch was phosphorylated with Na2HPO4, HVED was more efficient in catalyzing reaction (3.89 mg P/kg for 30 min HVED in relation to 0.43 mg P/kg for thermal treatment), whereas with Na5P3O10 similar P content was achieved as with thermal treatment (0.76 P/kg for 30 min HVED in relation to 0.86 mg P/kg). The order of HVED and chemical reactions did not have a marked effect on phosphorous content. In combination with Na2HPO4, HVED pre-treatment had a more pronounced effect on the solubility and water absorption, whereas post-treatment was favoured with Na5P3O10. Mean diameter was increased by all treatments, where HVED had a marked effect. Enthalpy of gelatinization ranged from 11.76 J/g for starch treated with Na5P3O10 and 10 min-HVED to 13.58 J/g for Na5P3O10 treated sample. G′ and G″ increased after both thermally and HVED enhanced phosphorylations, with a slightly more pronounced effect of the HVED.

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Lojková, Lea, Sanja Zec Zrinušić, Helena Pluháčková, Radim Cerkal e Tihana Marček. "The effect of high voltage electrical discharge (HVED) treatment on small seed plants". Croatian journal of food science and technology 16, n. 1 (19 giugno 2024): 45–55. http://dx.doi.org/10.17508/cjfst.2024.16.1.04.

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The High Voltage Electrical Discharge (HVED) is a physical hydropriming method which alters the physicochemical properties of water, creating the plasma activated water (PAW). The mixture of highly reactive ions and molecules can break down the seed dormancy and speed up the growing process. Previous studies presented the promotional role of HVED technology on the germination, growth and polyphenol content. The aim of this study was to explore the effect of HVED technology on germination ability and vitality of three types of seeds with low germination rate. Selected species included carrot (Daucus carota L.), melilot (Melilotus albus Medik.), and mallow (Malva verticillata L.). In carrot and mallow, HVED (20Hz/30s) significantly promoted germination percentage, whilst in melilot seeds, germination was unchanged. HVED treatment enhanced the growth of shoots and roots in both carrot and mallow. In melilot, shorter treatment time of exposure to high voltage (30Hz/10s) resulted in longer shoots and roots. Perspectives of HVED as a method for improvement of germination exist, especially in mellow and carrot, but it is necessary to optimize the process parameters for each type of seed separately.

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Ačkar, Đurđica, Marijana Grec, Ivanka Grgić, Artur Gryszkin, Marzena Styczyńska, Antun Jozinović, Borislav Miličević, Drago Šubarić e Jurislav Babić. "Physical Properties of Starches Modified by Phosphorylation and High-Voltage Electrical Discharge (HVED)". Polymers 14, n. 16 (17 agosto 2022): 3359. http://dx.doi.org/10.3390/polym14163359.

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High-voltage electrical discharge (HVED) is considered as a novel, non-thermal process and is currently being researched regarding its effect on microorganisms (decontamination of food), waste water treatment, and modification of different compounds and food components. In this paper, four native starches (maize, wheat, potato, and tapioca) were treated with HVED, phosphorylated with Na2HPO4 and Na5P3O10, and modified by a combination of HVED with each phosphorylation reaction both prior and after chemical modification. Pasting properties, swelling power, solubility, gel texture, and particle size were analyzed. Although HVED induced lower contents of P in modified starches, it had an effect on analyzed properties. The results revealed that HVED treatment alone had a limited effect on pasting properties of starches, but it had an effect on properties of phosphorylated starches, both when it was conducted prior and after the chemical modification, reducing the influence of Na5P3O10 and Na2HPO4 on the decrease of pasting temperature. With minor exceptions, the gel strength of starches increased, and the rupture strength decreased by all modifications. HVED treatment resulted in a decrease of the particle size after the modification of maize and wheat starches, while potato and tapioca starches were not significantly influenced by the treatment.

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Marček, Tihana, Kamirán Áron Hamow, Tibor Janda e Eva Darko. "Effects of High Voltage Electrical Discharge (HVED) on Endogenous Hormone and Polyphenol Profile in Wheat". Plants 12, n. 6 (8 marzo 2023): 1235. http://dx.doi.org/10.3390/plants12061235.

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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.

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Marček, Tihana, Tihomir Kovač, Katarina Jukić, Ante Lončarić e Maja Ižaković. "Application of High Voltage Electrical Discharge Treatment to Improve Wheat Germination and Early Growth under Drought and Salinity Conditions". Plants 10, n. 10 (9 ottobre 2021): 2137. http://dx.doi.org/10.3390/plants10102137.

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The environmentally friendly, physical method of high voltage electrical discharge (HVED) was developed to improve the drought and salinity tolerance of two wheat genotypes. Unlike other plasma technologies, HVED treatment involves the discharge of electricity in water. In this study, the effect of HVED pretreatment on wheat germination and early vegetative growth under drought (0%, 15%, 20% and 30% PEG) and salinity (0, 90, 160 and 230 mM NaCl) stress conditions was investigated. HVED-exposed seeds showed altered seed surfaces and became more permeable to water uptake, resulting in higher germination percentages, germination index values, and shoot and root growth under the control and all drought and salinity concentrations. Moreover, the electrical conductivity of the water medium increased significantly, indicating HVED-induced reactions of ionization and dissociations of water molecules occurred. In addition, HVED pretreatment in the salt experiment improved the tolerance index values of the shoots and roots. The most pronounced genotypic variations occurred under the highest stress levels (30% PEG or 230 mM NaCl) and varied with the stress intensity and growth stage. The study results indicate that HVED pretreatment has the potential to improve drought and salt tolerance in wheat.

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Tomašević, Marina, Karin Kovačević Ganić, Katarina Lukić, Natka Ćurko, Tomislava Vukušić e Stela Križanović. "Potential application of high voltage electrical discharge plasma control of Brettanomyces bruxellensis in wine". Glasnik zaštite bilja 42, n. 5 (31 ottobre 2019): 54–60. http://dx.doi.org/10.31727/gzb.42.5.6.

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The aim of this work was to investigate the effect of high voltage electrical discharge (HVED) plasma on inactivation of Brettanomyces bruxellensis yeast in red wine. Research was conducted in two phases. Firstly, the efficacy of two main plasma parameters was examined - frequency (60, 90 and 120 Hz) and treatment duration (3, 5, 10, 20 and 30 min). Second phase included monitoring long-term effect of HVED plasma using optimal frequency during selected treatment durations, where culturability of B. bruxellensis was determined after 30, 60 and 90 days of storage. Results show that frequency of 120 Hz caused slightly higher inactivation than the lower ones. Furthermore, longer treatment durations resulted in significantly higher inactivation, wherein the treatment of 30 min showed the best results. Finally, during storage period, the inactivation effect of HVED plasma was reversed and B. bruxellensis yeast recovered almost completely in treated wine.

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Barišić, Veronika, Ivana Flanjak, Mirela Kopjar, Mirta Benšić, Antun Jozinović, Jurislav Babić, Drago Šubarić et al. "Does High Voltage Electrical Discharge Treatment Induce Changes in Tannin and Fiber Properties of Cocoa Shell?" Foods 9, n. 6 (19 giugno 2020): 810. http://dx.doi.org/10.3390/foods9060810.

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Cocoa shell is a by-product of the chocolate industry that is rich in dietary fiber and bioactive components. In this research, the influence of high voltage electric discharge (HVED) treatment on chemical and physical characteristics of the cocoa shell, i.e., the effects of applied time and frequencies on grinding ability, water binding capacity (WBC), dietary fibers and tannin content was investigated. HVED had a significant influence on the chemical and physical properties of cocoa shell, all of which could be linked to changes in fiber properties. Along with the fiber content, grinding ability and water binding capacity were increased. These properties have already been linked to fiber content and soluble/insoluble fiber ratio. However, this research implies that change in fiber properties could be linked to tannin formation via complexation of other polyphenolic components. Additional research is needed to verify this effect and to establish mechanisms of tannin formation induced by HVED and its influence on fiber quantification.

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Tiban, Nela Nedić, Mirela Šimović, Martina Polović, Antonija Šarić, Ivana Tomac, Petra Matić e Lidija Jakobek. "The Effect of High Voltage Electrical Discharge on the Physicochemical Properties and the Microbiological Safety of Rose Hip Nectars". Foods 11, n. 5 (23 febbraio 2022): 651. http://dx.doi.org/10.3390/foods11050651.

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Although neglected as an industrial raw material, rose hip has been important for both nutritional and medical purposes for centuries. The main goal of this study was to propose a rapid and inexpensive non-thermal technique such as high voltage electrical discharge (HVED) to preserve valuable rose hip bioactive compounds, towards the development of high-quality products, including low-calorie products. The objective of this work was to evaluate the effects of HVED on the physicochemical properties and the microbiological safety of rose hip nectar formulations and, for comparison, on a pasteurised sample. Physicochemical analysis proved that rose hip pulp and the prepared nectars were valuable sources of polyphenols and ascorbic acid with high antioxidant activity. The HVED technique had minimal effects on the quality characteristics of the nectars under the different process conditions (50, 100 Hz; 10, 15, 20 min). In addition, the pasteurised nectar showed the greatest loss of ascorbic acid (54%) and phenolic compounds (40%). The microbiological quality of nectars was examined immediately after preparation/treatment and after 6 and 12 days of storage at 4 °C. In addition to the pasteurised sample, HVED-treated rose hip nectar prepared from microwave-blanched puree with extended shelf life had satisfactory microbiological safety after storage.

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Nutrizio, Marinela, Jasenka Gajdoš Kljusurić, Zvonimir Marijanović, Igor Dubrović, Marko Viskić, Elena Mikolaj, Farid Chemat e Anet Režek Jambrak. "The Potential of High Voltage Discharges for Green Solvent Extraction of Bioactive Compounds and Aromas from Rosemary (Rosmarinus officinalis L.)—Computational Simulation and Experimental Methods". Molecules 25, n. 16 (14 agosto 2020): 3711. http://dx.doi.org/10.3390/molecules25163711.

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Rosemary (Rosmarinus officinalis L.) is a Mediterranean medicinal and aromatic plant widely used due to valuable bioactive compounds (BACs) and aromas. The aim of the study was to evaluate the extraction of intracellular compounds from rosemary combining experimental procedure by means of high voltage electrical discharge (HVED), with a theoretical approach using two computational simulation methods: conductor-like screening model for real solvents and Hansen solubility parameters. The optimal HVED parameters were as follows: frequency 100 Hz, pulse width 400 ns, gap between electrodes 15 mm, liquid to solid ratio 50 mL/g, voltage 15 and 20 kV for argon, and 20 and 25 kV for nitrogen gas. Green solvents were used, water and ethanol (25% and 50%). The comparison was done with modified conventional extraction (CE) extracted by magnetic stirring and physicochemical analyses of obtained extracts were done. Results showed that HVED extracts in average 2.13-times higher total phenol content compared to CE. Furthermore, nitrogen, longer treatment time and higher voltage enhanced higher yields in HVED extraction. HVED was confirmed to have a high potential for extraction of BACs from rosemary. The computational stimulation methods were confirmed by experimental study, ethanol had higher potential of solubility of BACs and aromas from rosemary compared to water.

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Žuntar, Irena, Predrag Putnik, Danijela Bursać Kovačević, Marinela Nutrizio, Filip Šupljika, Andreja Poljanec, Igor Dubrović, Francisco Barba e Anet Režek Jambrak. "Phenolic and Antioxidant Analysis of Olive Leaves Extracts (Olea europaea L.) Obtained by High Voltage Electrical Discharges (HVED)". Foods 8, n. 7 (8 luglio 2019): 248. http://dx.doi.org/10.3390/foods8070248.

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Background: The aim of this study was to evaluate high voltage electrical discharges (HVED) as a green technology, in order to establish the effectiveness of phenolic extraction from olive leaves against conventional extraction (CE). HVED parameters included different green solvents (water, ethanol), treatment times (3 and 9 min), gases (nitrogen, argon), and voltages (15, 20, 25 kV). Methods: Phenolic compounds were characterized by ultra-performance liquid chromatography-tandem mass spectrometer (UPLC-MS/MS), while antioxidant potency (total phenolic content and antioxidant capacity) were monitored spectrophotometrically. Data for Near infrared spectroscopy (NIR) spectroscopy, colorimetry, zeta potential, particle size, and conductivity were also reported. Results: The highest yield of phenolic compounds was obtained for the sample treated with argon/9 min/20 kV/50% (3.2 times higher as compared to CE). Obtained results suggested the usage of HVED technology in simultaneous extraction and nanoformulation, and production of stable emulsion systems. Antioxidant capacity (AOC) of obtained extracts showed no significant difference upon the HVED treatment. Conclusions: Ethanol with HVED destroys the linkage between phenolic compounds and components of the plant material to which they are bound. All extracts were compliant with legal requirements regarding content of contaminants, pesticide residues and toxic metals. In conclusion, HVED presents an excellent potential for phenolic compounds extraction for further use in functional food manufacturing.

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Banožić, Marija, Antun Jozinović, Jovana Grgić, Borislav Miličević e Stela Jokić. "High Voltage Electric Discharge for Recovery of Chlorogenic Acid from Tobacco Waste". Sustainability 13, n. 8 (16 aprile 2021): 4481. http://dx.doi.org/10.3390/su13084481.

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Three fractions of tobacco waste (scrap, dust and midrib) were subjected to a high voltage electric discharge (HVED) assisted extraction procedure under different experimental conditions: solvent:solid ratio (300, 500, 700 mL/g), frequency (40, 70, 100 Hz) and treatment time (15, 30, 45 min), in order to study the influence of these conditions on the content of chlorogenic acid. The content of chlorogenic acid ranged from 1.54 to 3.66 mg/100 g for scrap, from 1.90 to 2.97 mg/100 g for dust, and from 2.30 to 3.38 mg/100 g for midrib extract, showing a strong dependence on the applied process parameters. The temperature change and the change in pH and electrical conductivity of the extracts after high voltage discharge treatment were also observed. The studied process parameters showed a statistically significant effect on the chemical and physical properties of the extracts from tobacco waste as well as on the content of chlorogenic acid, indicating the potential of HVED assisted processes in the separation of chlorogenic acid from tobacco industry waste. Multiple regression analysis was used to fit the results for the chlorogenic acid to a second order polynomial equation and the optimum conditions were determined.

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McReynolds, Colin, Amandine Adrien, Antoine Silvestre de Ferron, Nadia Boussetta, Nabil Grimi, Laurent Pecastaing e Susana C. M. Fernandes. "Extraction of Mycosporine-like Amino Acids and Proteins from the Agarophyte Gelidium corneum Using Pulsed Power Techniques". Foods 12, n. 7 (30 marzo 2023): 1473. http://dx.doi.org/10.3390/foods12071473.

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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.

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Ivanov, Mia, Tomislava Vukušić Pavičić, Klara Kraljić, Dijana Grgas, Tibela Landeka Dragičević e Zoran Herceg. "Effects of High Voltage Electrical Discharge Plasma on Olive Mill Wastewater Treatment". Sustainability 13, n. 3 (2 febbraio 2021): 1552. http://dx.doi.org/10.3390/su13031552.

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High voltage electrical discharge plasma technology (HVED) is considered as a promising technology for wastewater remediation due to its fast removal rate and environmental compatibility. Olive mill wastewater (OMWW) treatment presents crucial environmental issues because of its high organic load and intense toxicity and phytotoxicity. The effect of cold plasma at frequencies of 60 Hz and 120 Hz, with injected gas (air, oxygen and nitrogen) and with and without the addition of FeCl3x6H2O, during 30 min, on degradation and removal of organic compounds, as well as polyphenols from OMWW, were investigated. The efficiency of cold plasma was monitored by pH, temperature, electroconductivity, redox potential, oxygen saturation and reduction of chemical oxygen demand (COD) and polyphenols. The best removal efficiency of 50.98% of organic compounds was achieved at 120 Hz with nitrogen and the addition of FeCl3x6H2O, and a 60.32% reduction of polyphenols at a frequency of 60 Hz with the air and FeCl3x6H2O added was obtained. Also, the plasma treatment resulted in a decrease in coloring intensity, with the most significant color change at 120 Hz with the addition of FeCl3x6H2O with nitrogen and air.

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Kandrotaitė Janutienė, Rasa, Olha Syzonenko, Darius Mažeika, Laura Gegeckienė, Ingrida Venytė e Andrii Torpakov. "Microstructure and Phase Composition of Ti-Al-C Materials Obtained by High Voltage Electrical Discharge/Spark Plasma Sintering". Materials 17, n. 1 (25 dicembre 2023): 115. http://dx.doi.org/10.3390/ma17010115.

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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.

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Smirnov, A. P., e O. V. Khvoshchan. "Experimental Studies of Hydrodynamic and Energy Characteristics of a High-Voltage Electrochemical Explosion in Limited Liquid Volumes". Elektronnaya Obrabotka Materialov 59, n. 5 (novembre 2023): 42–55. http://dx.doi.org/10.52577/eom.2023.59.5.42.

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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.

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Nutrizio, Marinela, Gianpiero Pataro, Daniele Carullo, Serena Carpentieri, Luisa Mazza, Giovanna Ferrari, Farid Chemat, Mara Banović e Anet Režek Jambrak. "High Voltage Electrical Discharges as an Alternative Extraction Process of Phenolic and Volatile Compounds from Wild Thyme (Thymus serpyllum L.): In Silico and Experimental Approaches for Solubility Assessment". Molecules 25, n. 18 (10 settembre 2020): 4131. http://dx.doi.org/10.3390/molecules25184131.

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The objective of this study was to evaluate the potential of green solvents for extractions of bioactive compounds (BACs) and essential oils from wild thyme (Thymus serpyllum L.) using theoretical and experimental procedures. Theoretical prediction was assessed by Hansen solubility parameters (HSPs) and conductor-like screening model for realistic solvents (COSMO-RS), to predict the most suitable solvents for extraction of BACs. An experimental procedure was performed by nonthermal technology high voltage electrical discharge (HVED) and it was compared with modified conventional extraction (CE). Obtained extracts were analyzed for chemical and physical changes during the treatment. Theoretical results for solution of BACs in ethanol and water, as green solvents, were confirmed by experimental results, while more accurate data was given by COSMO-RS assessment than HSPs. Results confirmed high potential of HVED for extraction of BACs and volatile compounds from wild thyme, in average, 2.03 times higher yield of extraction in terms of total phenolic content was found compared to CE. The main phenolic compound found in wild thyme extracts was rosmarinic acid, while the predominant volatile compound was carvacrol. Obtained extracts are considered safe and high-quality source reach in BACs that could be further used in functional food production.

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Barišić, Veronika, Jovana Petrović, Ivana Lončarević, Ivana Flanjak, Drago Šubarić, Jurislav Babić, Borislav Miličević, Kristina Doko, Marijana Blažić e Đurđica Ačkar. "Physical Properties of Chocolates Enriched with Untreated Cocoa Bean Shells and Cocoa Bean Shells Treated with High-Voltage Electrical Discharge". Sustainability 13, n. 5 (1 marzo 2021): 2620. http://dx.doi.org/10.3390/su13052620.

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Recently, the enrichment of chocolate has become a very interesting topic, along with the management of food industry by-products, such as cocoa shells. Cocoa shells could be a great raw material for the cocoa industry, both for economical reasons (maximized utilization of cocoa beans) and for their functional properties (increased fiber content). In this research, we used untreated and high-voltage electrical discharge (HVED)-treated cocoa shells in the production of chocolate. Different proportions of cocoa mass were replaced with cocoa shells to produce dark and milk chocolates in a ball mill. Additionally, dark chocolate with 15% and milk chocolate with 5% of shells were chosen for further research and to study the alteration of the composition. The rheology, particle size distribution, hardness, and color were determined for all the prepared samples. Treated cocoa shells provided chocolates with inferior physical properties compared to chocolates with untreated shells. Therefore, untreated cocoa shells were selected for further analysis. The addition of both treated and untreated cocoa shells resulted in softening and darkening of samples, which could have a positive effect for consumers. On the other hand, the particle size distribution and rheology were negatively affected. Further research is needed to find a solution for these problems.

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Cai, Zhixiang, Hui Zhang, Kerou Liu, Yufei Chen e Qing Yu. "Experimental Investigation and Mechanism Analysis on Rock Damage by High Voltage Spark Discharge in Water: Effect of Electrical Conductivity". Energies 13, n. 20 (18 ottobre 2020): 5432. http://dx.doi.org/10.3390/en13205432.

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High voltage spark discharge (HVSD) could generate strong pressure waves that can be combined with a rotary drill bit to improve the penetration rate in unconventional oil and gas drilling. However, there has been little investigation of the effect of electrical conductivity on rock damage and the fragmentation mechanism caused by HVSD. Therefore, we conducted experiments to destroy cement mortar, a rock-like material, in water with five conductivity levels, from 0.5 mS/cm to 20 mS/cm. We measured the discharge parameters, such as breakdown voltage, breakdown delay time, and electrical energy loss, and investigated the damage mechanism from stress waves propagation using X-ray computed tomography. Our study then analyzed the influence of conductivity on the surface damage of the sample by the pore size distribution and the cumulative pore area, as well as studied the dependence of internal damage on conductivity by through-transmission ultrasonic inspection technique. The results indicated that the increase in electrical conductivity decreased the breakdown voltage and breakdown delay time and increased the energy loss, which led to a reduction in the magnitude of the pressure wave and, ultimately, reduced the sample damage. It is worth mentioning that the relationship between the sample damage and electrical conductivity is non-linear, showing a two-stage pattern. The findings suggest that stress waves induced by the pressure waves play a significant role in sample damage where pores and two types of tensile cracks are the main failure features. Compressive stresses close horizontal cracks inside the sample and propagate vertical cracks, forming the tensile cracks-I. Tensile stresses generated at the sample–water interface due to the reflection of stress waves produce the tensile cracks-II. Our study is the first to investigate the relationship between rock damage and electrical conductivity, providing insights to guide the design of drilling tools based on HVSD.

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Ketegenov, Tlek, Kaster Kamunur, Lyazzat Mussapyrova, Aisulu Batkal e Rashid Nadirov. "Enhancing Rare Earth Element Recovery from Coal Ash Using High-Voltage Electrical Pulses and Citric Acid Leaching". Minerals 14, n. 7 (3 luglio 2024): 693. http://dx.doi.org/10.3390/min14070693.

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The study investigates the application of high-voltage electrical pulses (HVEP) as a pretreatment to enhance the leaching efficiency of rare earth elements (REE) from coal ash (CA) produced from the combustion of Ekibastuz Basin coal in Almaty, Kazakhstan. HVEP treatment was applied to the finest (<40 µm) non-magnetic fraction of CA under controlled conditions, optimizing discharge current, voltage, and treatment duration. Leaching experiments with 1 M citric acid at various solid-to-liquid ratios, temperatures, and durations were conducted on both treated and untreated samples. Results indicated that HVEP-treated CA significantly improved REE recovery rates compared to untreated samples, with optimal conditions achieving 74% cerium, 79% yttrium, and 77% lanthanum recovery. The leaching of untreated CA under the specified conditions allowed no more than 28% REE to be extracted into the solution. The leaching process was found to follow first-order kinetics, with the chemical reaction of metal dissolution being the rate-limiting step.

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Li, Changping, Xiaohui Wang, Longchen Duan e Bo Lei. "Study on a Discharge Circuit Prediction Model of High-Voltage Electro-Pulse Boring Based on Bayesian Fusion". Energies 15, n. 10 (23 maggio 2022): 3824. http://dx.doi.org/10.3390/en15103824.

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Abstract (sommario):

It is necessary to develop new drilling and breaking technology for hard rock construction. However, the process of high-voltage electro-pulse (HVEP) rock-breaking is complex, and the selection of electro-pulse boring (EPB) process parameters lacks a theoretical basis. Firstly, the RLC model, TV-RLC model, and TV-CRLC model are established based on the characteristics of the HVEP circuit to predict the EPB dynamic discharge curve. Secondly, the parameters are identified by the Particle Swarm Optimization Genetic Algorithm (PSO-GA). Finally, due to the nonlinear and complex time-varying characteristics of the discharge circuit, the discharge circuit prediction models based on Bayesian fusion and current residual normalization fusion method are proposed, and the optimal weight of these three models is determined. Compared with the single models for EPB current prediction, the average relative error reduction rates based on Bayesian fusion and current residual normalization fusion methods are 25.5% and 9.5%, respectively. In this paper, the discharge circuit prediction model based on Bayesian fusion is established, which improves the prediction accuracy and reliability of the model, and it guides the selection of process parameters and the design of pulse power supply and electrode bits.

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21

Lončarić, Ante, Maria Celeiro, Antun Jozinović, Josip Jelinić, Tihomir Kovač, Stela Jokić, Jurislav Babić, Tihomir Moslavac, Sandra Zavadlav e Marta Lores. "Green Extraction Methods for Extraction of Polyphenolic Compounds from Blueberry Pomace". Foods 9, n. 11 (23 ottobre 2020): 1521. http://dx.doi.org/10.3390/foods9111521.

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Abstract (sommario):

In this study, green extraction methods—high voltage electrical discharges (HVED), pulsed electric field (PEF), and ultrasound-assisted extraction (UAE)—were compared in terms of extraction yield of total and individual polyphenolic compounds, as well as the antioxidant capacity of blueberry pomace extracts. All extractions were performed with methanol- and ethanol-based solvents. The highest total polyphenols content (TPC) (10.52 mg of gallic acid equivalent (GAE) per g of dry weight (dw)) and antioxidant activity (AA) (0.83 mmol TE/g dw) were obtained by PEF-assisted extraction in the ethanol-based solvent after 100 pulses and 20 kV/cm, which corresponds to an energy input of 41.03 kJ/kg. A total of eighteen individual polyphenols were identified in all investigated blueberry pomace extracts by high-performance liquid chromatography with the diode-array detector (HPLC-DAD) and liquid chromatography electrospray ionization tandem mass spectrometric (LC-(HESI)-MS/MS). The highest anthocyanin (1757.32 µg/g of dw) and flavanol (297.86 µg/g of dw) yields were obtained in the methanol-based solvent, while the highest phenolic acid (625.47 µg/g of dw) and flavonol (157.54 µg/g of dw) yields were obtained in the ethanol-based solvent by PEF-assisted extraction at the energy input of 41.03 kJ/kg. These results indicated that PEF is a promising green extraction method which can improve the blueberry pomace’s polyphenol extraction yield.

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22

Zhang, Qingyu, Guanglin Wang, Xudong Pan, Yuefeng Li, Jianqi He, Yue Qi e Juesuan Yang. "High Voltage Electric Pulse Drilling: A Study of Variables through Simulation and Experimental Tests". Energies 16, n. 3 (20 gennaio 2023): 1174. http://dx.doi.org/10.3390/en16031174.

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Abstract (sommario):

With the deepening of drilling depth, the difficulty of drilling engineering increases gradually due to the complex geological conditions. The traditional mechanical drilling method shows the problems of high energy consumption, low efficiency, long cycle and high cost. Because of the characteristics of rock, the high abrasiveness of rock causes great wear to the bit, which becomes an important factor affecting the drilling rate. High voltage electric pulse (Abbreviated as HVEP later in this paper) drilling technology is a new technology developed in the past several decades. The technology uses plasma channel, water jet or shock wave generated by high voltage electric pulse discharge to break rock. It has the characteristics of environmental protection, directional breaking, easy control of rock breaking process and fast speed in the face of complex hard rock. In this paper, the mechanism and technology of rock breaking by high voltage electric pulse method in deep drilling are studied, and the functional test is carried out.

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23

Galtseva, Olga, Sergey Bordunov, Alexandr Zhiganov, Inna Plotnikova e Jian Min Li. "Technology of Gold-Containing Technogenic Raw Materials Processing Using the Electric Explosion Method". Materials Science Forum 942 (gennaio 2019): 30–39. http://dx.doi.org/10.4028/www.scientific.net/msf.942.30.

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Abstract (sommario):

The paper shows fundamental possibility of processing of gold-bearing technogenic raw materials using the method of electric explosion. A series of experiments using a laboratory and pilot-production high-voltage pulsed discharge (HVPD) installation for the processes of enrichment of gold-bearing mineral raw materials of Komsomolsk mine tailings in Kemerovo region is conducted with a relatively low energy electrical discharge in the pulse of up to 112.5 Joules and the cost of electric power of about 1.5 kW/ton of raw material, that allows complete destruction of clay components agglomerations to less than 0.045 mm (micron and submicron sizes). Solid minerals such as quartz are simultaneously destroyed by defects in the grains and withdrawn from the installation with water, thus increasing gold degree of the concentrate. The results of particle-size and X-ray structural analyses of gold-bearing mineral raw materials of Komsomolsk mine tailings in Kemerovo region obtained by the method of electric explosion are discussed.

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24

Esehaghbeygi, Ali, Arash Hajisadeghian e Masih Nasri Nasrabadi. "Role of a corona field application in the physicochemical properties of stored strawberries". Research in Agricultural Engineering 67, No. 2 (25 giugno 2021): 58–64. http://dx.doi.org/10.17221/50/2020-rae.

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Abstract (sommario):

Grey mould disease caused by the fungus Botrytis cinerea Pers is widely distributed on strawberries as the dominant postharvest disease. Therefore, fruits have been treated using a pin-to-plate corona electrical field at a high voltage electric field (HVEF) intensity of 3.61, 4.56, and 5.13 kV·cm–1 for 60 minutes. The result revealed that the corona discharge demolished the B. cinerea growth using 20 kV·cm–1 for 10 min in the Petri dishes. In addition, the treated strawberries at 4.56 kV·cm–1 had an average infection rate of 23.33% compared with non-treated samples rate of 45.33%. The HVEF-treated samples showed significantly lower mass losses. The analysis of variance showed that the HVEF did not significantly affect the total soluble solids content, pH, titratable acidity, and softness; however, the lower acidity affected the Botrytis cinerea growth. No significant differences were observed among the mean values in the colour change parameters and colour difference for 4.56 kV·cm–1 compared with the control, while the lightness was significantly higher. The result show that the corona electrical field was able to demolish the B. cinerea growth, and an electric field intensity at 4.56 kV·cm–1 was found to extend the strawberries' cold storage and to lead to a lower mass loss.

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25

Jokić, Stela, Nika Pavlović, Antun Jozinović, Đurđica Ačkar, Jurislav Babić e Drago Šubarić. "High-Voltage Electric Discharge Extraction of Bioactive Compounds from the Cocoa Bean Shell". Chemical & biochemical engineering quarterly 33, n. 2 (2019): 271–80. http://dx.doi.org/10.15255/cabeq.2018.1525.

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Abstract (sommario):

This study is focused on the application of high-voltage electric discharge (HVED) to recover some bioactive compounds from the cocoa bean shell. Different extraction times (30, 60, 90 min), frequencies (40, 70, 100 Hz) and solvent-solid ratios (10, 30 and 50 mL g–1) were used to obtain cocoa bean shell extracts. Desired bioactive compounds, methylxanthines and phenolic compounds were measured in obtained extracts by high-pressure liquid chromatography with diode array detector. The obtained extracts showed that theobromine was the most abundant, ranging from 2530.13 to 6031.51 mg kg–1, while caffeine content was in the range from 316.08 to 849.88 mg kg–1. In addition, significant amounts of phenolic compounds were found, namely catechin (115.91 to 284.33 mg kg–1), epicatechin (20.20 to 358.90 mg kg–1), and gallic acid (80.28 to 219.17 mg kg–1). Results showed that different parameters of HVED extraction have statistically significant influence on cocoa bean shell composition, suggesting how this byproduct can be used in the production of valuable extracts.

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26

Sizonenko, O. N., E. G. Grigoryev, N. S. Pristash, A. D. Zaichenko, A. S. Torpakov, Ye V. Lypian, V. A. Tregub, A. G. Zholnin, A. V. Yudin e A. A. Kovalenko. "Plasma Methods of Obtainment of Multifunctional Composite Materials, Dispersion-Hardened by Nanoparticles". High Temperature Materials and Processes 36, n. 9 (26 settembre 2017): 891–96. http://dx.doi.org/10.1515/htmp-2016-0049.

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Abstract (sommario):

AbstractHigh voltage electric discharge (HVED) in disperse system “hydrocarbon liquid – powder” due to impact of plasma discharge channel, electromagnetic fields, shock waves mechanical impact, hydro flows and volume microcavitation leads to synthesis of nanocarbon, metal powders dispersion and synthesis of micro- (from 10−6 to 10−7 m) and nanosized (from 10−7 to 10−9 m) composite powders of hardening phases. Spark plasma sintering (SPS) of powder mixtures allows targeted control of grain growth rate and thus allows obtainment of multifunctional composite materials dispersion hardened by nanoparticles. Processes of HVED synthesis of micro- and nanosized powders of new compositions from elemental metal powders and their mixtures with the subsequent application of high-speed SPS of obtained powders create conditions for increase of strength (by 10–20 %), hardness and wear-resistance (by 30–60 %) of obtained materials.

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27

Debs, Espérance, Anna-Maria Abi-Khattar, Hiba N. Rajha, Roula M. Abdel-Massih, Jean-Claude Assaf, Mohamed Koubaa, Richard G. Maroun e Nicolas Louka. "Valorization of Olive Leaves through Polyphenol Recovery Using Innovative Pretreatments and Extraction Techniques: An Updated Review". Separations 10, n. 12 (29 novembre 2023): 587. http://dx.doi.org/10.3390/separations10120587.

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Abstract (sommario):

Olive leaves are naturally generated as a by-product during olive harvesting and olive oil production. Usually discarded with no specific use, they are a valuable source of bioactive compounds that should not be overlooked. Their valorization must therefore be achieved through the recovery of their polyphenols using an ecological strategy. Conventional extraction is commonly known as an energy- and solvent-consuming process, whereas emerging and innovative extraction technologies, such as ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE), pulsed-electric-field-assisted extraction (PEF), high-voltage-electric-discharge-assisted extraction (HVED), supercritical fluid extraction (SFE), infrared-assisted extraction (IAE), and “Intensification of Vaporization by Decompression to the Vacuum” (IVDV), are considered more sustainable and environmentally friendly. The aim of this review is to provide a comprehensive and updated overview of the valorization of olive leaves through both pretreatment and extraction techniques via an analysis of the recovered polyphenols and their potential applications.

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28

Gulski, E. "Discharge pattern recognition in high voltage equipment". IEE Proceedings - Science, Measurement and Technology 142, n. 1 (1 gennaio 1995): 51–61. http://dx.doi.org/10.1049/ip-smt:19951632.

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29

Chadni, Morad, Nadia Boussetta, Cédric Guerin, Fabien Lagalle, Aya Zoghlami, Patrick Perré, Florent Allais, Nabil Grimi e Irina Ioannou. "Improvement of Sinapine Extraction from Mustard Seed Meal by Application of Emerging Technologies". Foods 12, n. 3 (23 gennaio 2023): 520. http://dx.doi.org/10.3390/foods12030520.

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Abstract (sommario):

Sinapine is a phenolic compound found in mustard (Brassica juncea) seed meal. It has numerous beneficial properties such as antitumor, neuroprotective, antioxidant, and hepatoprotective effects, making its extraction relevant. In this study, the extraction of sinapine was investigated using three methods: (i) from a mustard seed meal defatted by a supercritical CO2 (SC-CO2) pretreatment, (ii) by the implementation of high-voltage electrical discharges (HVEDs), (iii) and by the use of ultrasound. The use of SC-CO2 pretreatment resulted in a dual effect on the valorization of mustard seed meal, acting as a green solvent for oil recovery and increasing the yield of extracted sinapine by 24.4% compared to the control. The combination of ultrasound and SC-CO2 pretreatment further increased the yield of sinapine by 32%. The optimal conditions for ultrasound-assisted extraction, determined through a response surface methodology, are a temperature of 75 °C, 70% ethanol, and 100% ultrasound amplitude, resulting in a sinapine yield of 6.90 ± 0.03 mg/g dry matter. In contrast, the application of HVEDs in the extraction process was not optimized, as it led to the degradation of sinapine even at low-energy inputs.

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30

Vovchenko, А. I., L. Yu Demydenko, S. S. Kozyrev e L. E. Ovchinnikova. "High Voltage Electrochemical Explosion in Pulse-Discharge Technologies". Elektronnaya Obrabotka Materialov 58, n. 1 (febbraio 2022): 85–92. http://dx.doi.org/10.52577/eom.2022.58.1.85.

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Abstract (sommario):

The analysis and generalization of the results of studies of high-voltage electrochemical explosions (HVECHE) proceeding under various conditions, driven by special aspects and needs of the existing HVECHE based pulse-discharge technologies, was carried out. A methodology to calculate combined energy sources is proposed in relation to the needs of various discharge-pulse technologies using a high-voltage electrochemical explosion. Based on the analysis of the results of experimental studies, the advantage of using a high-voltage electrochemical explosion with a controlled input of electrical energy into the discharge channel was substantiated. An algorithm was developed to calculate the parameters of a combined electric-discharge source of a controlled HVECHE and the required mass of the exothermic composition which provides the energy characteristics specified by a specific discharge-pulse technology. The results of testing the developed calculation algorithm are presented confirming the possibility of its use for engineering calculations of combined power sources with a controlled input of electrical energy into the discharge channel.

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31

TOMIZAWA, Tomonori, Koji YOSHIDA, Hideo SHOJI e Hidenori TANAKA. "Fuel Injection System Using the High Voltage Electrical Discharge". Proceedings of Yamanashi District Conference 2002 (2002): 85–86. http://dx.doi.org/10.1299/jsmeyamanashi.2002.85.

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32

Smirnov, A. P., O. V. Khvoshchan e V. G. Zhekul. "Electrode Erosion During High-Voltage Electrical Discharge in a Liquid". Elektronnaya Obrabotka Materialov 58, n. 3 (giugno 2022): 21–33. http://dx.doi.org/10.52577/eom.2022.58.3.21.

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Abstract (sommario):

The paper presents the results of experimental studies of the mass value of electrode (anode) erosion during a high-voltage electric discharge in a liquid. The results obtained made it possible to determine the influence of technological parameters and operating conditions of high-voltage electric discharge installations on the mass erosion of an anode. It is noted that with an increase in the specific electrical conductivity of the working fluid and in the length of the interelectrode gap, a decrease in the value of the mass erosion of the anode is observed. Comparison of mass erosion of anodes made of copper, steel, and aluminum showed that among them the steel anode has the highest erosion resistance during an electric discharge in water. Based on the results of the performed experimental studies, an empirical technique was developed that allows to estimate the mass erosion of the anode in one electric discharge in water.

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33

Burany, Nandor, Laszlo Huber e Predrag Pejovic. "Corona Discharge Surface Treater Without High Voltage Transformer". IEEE Transactions on Power Electronics 23, n. 2 (marzo 2008): 993–1002. http://dx.doi.org/10.1109/tpel.2007.915760.

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34

Sobczyk, A. T., A. Jaworek, Eryk Rajch e Maria Sozańska. "Formation of Carbon Fibres in High-Voltage Low-Current Electrical Discharges". Solid State Phenomena 140 (ottobre 2008): 103–8. http://dx.doi.org/10.4028/www.scientific.net/ssp.140.103.

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Abstract (sommario):

A novel method to synthesize carbon fibres using low-current electrical-discharge plasma in hydrocarbon vapours is presented in the paper. The low-current arc discharge of positive polarity was generated between a stainless steel needle, and a nickel alloy plate, over a voltage range from 2 kV to 30 kV. The discharge was stabilised by a high series resistance (1 – 12.5 M'). The experiments were carried out in an argon atmosphere at normal temperature and atmospheric pressure. The arc discharge of current in the range of 1 to 4 milliamps was found to be a potentially effective method for the production of carbon fibres. The diameter of the fibres varied from about 20 to 120 μm with a growth rate of about 0.5 mm/s.

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35

Li, Zongming, Lei Liu, Yang Fan e Jun Xi. "Kinetic modeling for high voltage electrical discharge extraction based on discharge energy input". Food Chemistry 314 (giugno 2020): 126168. http://dx.doi.org/10.1016/j.foodchem.2020.126168.

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36

Pei, Jing Yu, Chang Ning Guo e De Jin Hu. "Electrical Discharge Grinding of Polycrystalline Diamond". Materials Science Forum 471-472 (dicembre 2004): 457–61. http://dx.doi.org/10.4028/www.scientific.net/msf.471-472.457.

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Abstract (sommario):

This paper presents the tests of electrical discharge grinding (EDG) of polycrystalline diamond (PCD) on electrical discharge machine tool with high speed rotating device. The effects of wheel speed, open circuit voltage, peak current, pulse on time, and pulse off time of EDG on the material removal rate (MRR), wheel wear rate (WWR) and surface roughness (SR) are investigated respectively. The tests indicate that it is possible to shape PCD blank with EDG. The wheel speed makes the MRR increase dramatically. The higher the open circuit voltage, the larger is the MRR. The effect of peak current on the MRR, WWR and the SR is similar with that of open circuit voltage. However, the influence of the peak current is much larger than that of the open circuit voltage. Moreover, the peak current should be smaller than 32A. There is a best ratio between the pulse on time and pulse off time. If a ratio is larger or smaller than that value, there may be adverse effect on the SR and the MRR. Large pulse on time makes the MRR increase and the WWR decrease. However, all the parameters investigated have little influence on the SR of PCD. The SR is determined mainly by the grain size of PCD.

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37

Mu, Xin, Ming Zhou, Shengzuo Yao e Jianwei Yang. "High Efficient Electrical Discharge Machining by Servo Voltage Adaptive Control". Procedia CIRP 68 (2018): 654–59. http://dx.doi.org/10.1016/j.procir.2017.12.149.

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38

Jun-liang, Ding, Wu Yun e Zhou You-tian. "Discharge characteristic and flow control experiment for pneumatic actuator of dielectric barrier discharge multistage plasma". International Journal of Electrical Engineering & Education 57, n. 1 (1 dicembre 2018): 41–53. http://dx.doi.org/10.1177/0020720918813815.

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Abstract (sommario):

Test and diagnosis of the characteristics of the air flow induced by the pneumatic actuation of the plasma are the important basis for the plasma flow control. In order to well understand the electrical characteristics of the pneumatic actuation of the plasma and the influence of the actuation voltage amplitude and the phase on the induced flow characteristics, the dielectric barrier discharge actuators symmetrically distributed were selected for the experimental research. The experiment result shows that the discharge form of the actuators symmetrically distributed is filamentary discharge, uniformly occurring around the high-voltage electrodes, and this is different from the discharge picture of the actuators asymmetrically distributed; when the voltage applied on the high-voltage electrode near to the actuators has the same amplitude and phase, the induced directional jet flow is vertical to the actuator surface, and the speed is at the order of meter per second; the change of the amplitude or phase of the voltage applied on the high-voltage electrode of the actuator can induce a jet flow towards the upper left or the upper right, but cannot effectively increase the induced airflow velocity.

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Lan, Yu Dan, e Li Ming He. "Electrical Characteristics Investigation of Transient Plasma Ignition". Applied Mechanics and Materials 110-116 (ottobre 2011): 503–7. http://dx.doi.org/10.4028/www.scientific.net/amm.110-116.503.

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Abstract (sommario):

A pseudo-spark based high repetition pulse generator is used, and a rapid charger (3μF) is used for repetitive discharge, and the frequency of typical discharge is 10 kHz. The pulse generator can provide pulse with duration of 1~2μs, which can be generated at 10~100 kHz maximum repetition rate in burst mode, with amplitudes up to 140 kV and 7 J of energy per ignition pulse. This paper studies the changing laws of voltage and current in TPI under different electrodes and discharge voltages. The result indicates that the use of screw thread electrode can increase the discharge times of TPI, reduce applied voltage without reducing the peak burst power. With the same time, TPI can raise the pulse energy and reduce pulse time by increasing voltage.

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40

Samira, Benharat, Belgacem Leila, Doufene Dyhia, Bouazabia Slimane, Haddad Abderrahmane e Sakmeche Mounir. "Electrical discharge reproduction in rod-barrier-plane system". Indonesian Journal of Electrical Engineering and Computer Science 34, n. 1 (1 aprile 2024): 1. http://dx.doi.org/10.11591/ijeecs.v34.i1.pp1-10.

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Abstract (sommario):

The present paper deals with new modeling to reproduce the electric discharge in the rod-plane air gap system with rubber insulating barrier under AC and impulse voltage. This model considers the randomness character of discharge evolution which is governed by the electric field. The discharges shape obtained by this model are compared with ones given by experimental tests. The established model reproduces correctly the forms of discharges obtained by experimental tests under AC voltage. It is found that the behavior of the electrical discharge depends not only on the dimension (thickness and width) of the insulating barriers but on its positions in the air gap as well. It is to highlight that the mode of applied voltage is of key importance barrier. Experimental investigation shows that the developed arc can evolve on 1 to 4 channels. The generated discharges in AC voltage distinguish by the formation of a multiple-channel arc. Whereas, the discharge under lightning impulse voltage found to progress in a single channel whatever the barrier position and dimensions. The model confirms that electric field is the most important factor in the behavior of the rod-insulating barrier-plane system submitted to high voltage.

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Wang, Xiaodong, e Jing Zhu. "Research and Applications of High-voltage Pulse Discharge Crushing". European Journal of Electrical Engineering 21, n. 2 (30 giugno 2019): 157–63. http://dx.doi.org/10.18280/ejee.210205.

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42

Aranda, Rosa María, Fátima Ternero, Beatriz Aranda, Juan Manuel Montes e Francisco G. Cuevas. "Low-Voltage Capacitor Electrical Discharge Consolidation of Iron Powder". Metals 12, n. 9 (31 agosto 2022): 1461. http://dx.doi.org/10.3390/met12091461.

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Abstract (sommario):

Commercially pure iron powder has been processed by the capacitor electrical discharge consolidation technique. This consolidation technique applies an external pressure and, at the same time, heats a metallic powder mass by the Joule effect of a high-voltage and high-intensity electric current. In this work, a capacitor charged at low voltage has been used instead. The effect of the initial porosity of the Fe powder mass, i.e., of the precompaction pressure, and the number of discharges from the capacitor have been studied. The densification and remaining porosity, the sintering level, the Vickers microhardness, and the electrical resistivity of the sintered compacts have been studied. Compacts sintered by the conventional powder metallurgy route of cold pressing and furnace sintering were also prepared for comparison. Results show that a high initial porosity provides a high electrical resistance in the powder column, a necessary requisite for the Joule effect to increase densification with the number of discharges. Thus, the final porosity decreases to 0.22 after 50 discharges in the powder mass with an initial porosity of 0.30. With this initial porosity, the sintering process increases Vickers microhardness from 29 to 51 HV10 and decreases the electrical resistivity of the powder mass from 3.53 × 10−2 to 5.38 × 10−4 Ω·m. An initial porosity of 0.2 does not make the compacts densify, but a certain bond between particles is attained, increasing microhardness and decreasing electrical resistivity as the number of discharges increases. Lower initial porosities make the powder mass behave as an electrical conductor with no appreciable changes even after 50 electrical discharges.

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Baranov, M. I. "A generalized physical principle of development of plasma channel of a high-voltage pulse spark discharge in a dielectric". Electrical Engineering & Electromechanics, n. 1 (1 gennaio 2024): 34–42. http://dx.doi.org/10.20998/2074-272x.2024.1.05.

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Abstract (sommario):

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.

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Moore, James H., C. W. Bray, S. T. Griffin, P. D. Mixon e J. C. Williams. "High-Voltage Monitor for Measuring Electrical Characteristics of Pulsed Hollow Cathode Discharges". Applied Spectroscopy 48, n. 10 (ottobre 1994): 1204–7. http://dx.doi.org/10.1366/0003702944027354.

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Abstract (sommario):

A high-voltage monitor has been developed for measuring small signal differences between large voltage waveforms. This device reduces the number of channels needed for a differential measurement from two to one while maximizing the performance of an oscilloscope by removing large common-mode signals present in typical discharge applications.

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45

Saveliev, A. S. "Formation of a Spray of Conducting Liquid under High Voltage and Electrical Discharge Plasma". Физика плазмы 49, n. 11 (1 novembre 2023): 1237–46. http://dx.doi.org/10.31857/s0367292123600966.

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Abstract (sommario):

The joint impact of an electrical discharge and a gas–droplet flow of a conducting liquid created by a centrifugal nozzle is studied. In the experiment, the electrical parameters of the discharge are recorded, and the local characteristics of the spray, namely, the droplet diameter distributions of the number of droplets and the components of their velocity vector are measured. The measurements are carried out using double shadow microphotography. The effect of a spray of a conducting liquid on the time-averaged electrical parameters of the discharge, as well as changes in the properties of the spray under the influence of high voltage and current, are studied. Additionally, the spray characteristics are measured when a high voltage of pre-breakdown value is applied. High-speed photography of a discharge in the presence of droplets of conducting liquid is carried out.

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46

Florkowski, M., e B. Florkowska. "Distortion of partial-discharge images caused by high-voltage harmonics". IEE Proceedings - Generation, Transmission and Distribution 153, n. 2 (2006): 171. http://dx.doi.org/10.1049/ip-gtd:20050008.

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VOEVODIN, Vadim V., Marina V. SOKOLOVA, Viktor R. SOLOV’YEV e Nikolay Yu LYSOV. "The Influence of Barrier and Applied Voltage Parameters on the Impulse Surface Discharge Characteristics". Elektrichestvo 11, n. 11 (2020): 17–27. http://dx.doi.org/10.24160/0013-5380-2020-11-17-27.

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Abstract (sommario):

The results from an experimental study of impulse surface discharge occurring in an electrode system containing a dielectric plate are presented. On one of its sides, the plate had a corona-producing electrode made of 50 mm thick copper foil grounded through a current shunt for measuring the discharge current. On its other side, the plate had a high-voltage electrode, to which the voltage from a pulse generator was applied. The article presents the results from measurements of the initial voltage and the sizes of the surface discharge area in air when applying single voltage pulses with different pulse front steepness in the range 0,1–3,4 kV/ms and amplitude in the range 7–15 kV. The measurements were carried out for different dielectric barrier materials with the e values from 2 to 35. The dielectric barrier thickness was 0,9–1,8 mm. The study results have shown that the initial surface discharge ignition voltage depends essentially on the voltage pulse parameters, whereas the barrier characteristics have a weaker effect on this voltage. It has been determined that the discharge has different discharge zone length and different structure depending on the dielectric barrier properties and applied voltage parameters. The streamer zone sizes decrease with increasing the barrier material e value at the same voltage pulse steepness and increase with increasing the steepness for each barrier material. The data obtained for a wide range of external conditions can be used in numerical modeling of discharge.

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Oßwald, K. Prof, D. Murnberger, T. Kappler e G. Sedlmayr. "High Speed Wire Electrical Discharge Machining*/High-Speed Wire Electrical Discharge Machining - An explorative study of a hybrid electro machining process". wt Werkstattstechnik online 106, n. 06 (2016): 430–38. http://dx.doi.org/10.37544/1436-4980-2016-06-60.

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Diese Untersuchung beschäftigt sich mit einer in den westlichen Industrienationen kaum bekannten Variante des Drahterodierens. Es wird zunächst ein Überblick über die Merkmale der Technologie (beispielsweise Aufbau, verwendeter Draht, Prozessflüssigkeit) gegeben, die sich teilweise deutlich von der konventionellen Technik unterscheiden. Des Weiteren werden die Verläufe von Strom und Spannung des Prozesses gemessen sowie die gefertigten Werkstückoberflächen untersucht.   This study deals with a variant of Wire Electrical Discharge Machining that is barely known in western industrialized countries. An overview of this technology‘s characteristics (setup, wire, fluid) is given, some of which are significantly different from conventional wire EDM (Electro Discharge Machining) technology. Furthermore, current and voltage profiles of the HSWEDM (High Speed Wire Electrical Discharge Machining) pulses are analyzed as well as the machined work piece surfaces.

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Arleevsky, I. P. "Some theoretical and clinical aspects of electro-pulse therapy for cardiac arrhythmias". Kazan medical journal 66, n. 6 (15 dicembre 1985): 470. http://dx.doi.org/10.17816/kazmj62284.

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It is shown that a high-voltage discharge of a capacitor causes two-phase changes in the transmembrane potential, impedance, electrical resistance, and parameters of the current-voltage characteristic, which are determined by the density of the discharge current.

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Denisyuk, T. D., A. R. Rizun e A. D. Blashchenko. "Investigation of Hydrodynamic Characteristics of Pulse-Wave Action for Various Technological Modes of Electric Discharge Installations for the Destruction of Non-Metallic Materials". Elektronnaya Obrabotka Materialov 60, n. 1 (marzo 2024): 80–88. http://dx.doi.org/10.52577/eom.2024.60.1.080.

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Abstract (sommario):

A method for the calculation of high voltage discharge channel parameters (pressure, radius, and expansion velocity) for electric discharge units for destruction of non-metallic materials is presented. It allowed to investigate the influence of installation parameters (inductance, voltage and capacitance) on the hydrodynamic parameters of the discharge channel and generated pressure wave. It is noted that increasing inductivity results in decreasing pressure and expanding discharge channel rate, increasing voltage results in increasing active characteristics of the discharge channel, and increasing capacitance results in increasing discharge current, while pressure and expanding discharge channel rate remaining practically unchanged. The effective area of destruction which depends on the parameters of the technological modes of the cycles, strength properties of the destructible material and electrical conductivity of the discharge medium were determined. The recommendations for selecting operating modes of electrodischarge installations for disintegration of non-metallic materials have been given.

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