11 results on '"Pulsed mode"'
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2. Membrane free alkaline sono-electrolysis for hydrogen production: An experimental approach.
- Author
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Merabet, Nour Hane and Kerboua, Kaouther
- Subjects
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HYDROGEN production , *NICKEL electrodes , *WATER electrolysis , *IONIC conductivity , *ELECTROLYTIC cells , *ELECTROLYSIS - Abstract
The present paper deals with hydrogen generation using sono-electrolysis. The experimental investigation is based on a parametric study of water electrolysis system according to the nature of the dissolved salt KOH/NaOH, the concentration of salt in the electrolyte, the temperatures of the electrolyte and the bath (27, 40, 45, 50, 55 and 60 °C), and the nature of the electrode (stainless steel 304, nickel, nickel foam and graphite). Two electrolyzer designs were adopted, namely Hoffmann cell and H-cell. The parametric study revealed the optimum configuration under silent conditions, before integrating the ultrasound power both in continuous and pulsed modes, in order to assess its effect on the energy efficiency of the process and the kinetics of hydrogen production. Under optimal conditions of electrolyte and electrode material, i.e., in KOH electrolyte using nickel foam electrodes, the integration of continuous ultrasound resulted in an increase of 7.78% in the cell current under ambient temperature, corresponding to 64% reduction in the bubble resistance. With the same configuration, the effect of sonication was negligible at the optimal solution temperature of 45 °C, while room temperature operation of the sono-electrolyzer conducted to a better performance than under silent conditions. Finally, continuous sonication mode led to the most performant operation with all the studied configurations, both kinetically and energetically, as compared to pulsed mode. • The geometry of the electrolytic cell controls the ionic transport between both anodic and cathodic compartments. • The effect of the electrolyte in sono-electrolysis is related to surface tension and ionic conductivity. • Heterogeneous solid liquid acoustic cavitation controls the kinetics of H 2 production by sono-electrolysis using nickel foam. • Continuous sono-electrolysis using KOH and nickel foam leads to 64% reductio of the bubble resistance. • Continuous sonication is the optimal mode in sono-electrolysis, both kinetically and energetically. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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3. A Model Describing the Process of the Electrodeposition of Zinc Loose Deposits in Pulsed Current Modes.
- Author
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Nikitin, V. S., Ostanina, T. N., Rudoy, V. M., and Ostanin, N. I.
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ELECTROPLATING , *DENDRITES , *DENSITY , *ELECTROLYSIS - Abstract
A phenomenological model describing the change in the structural characteristics of loose zinc deposits obtained in pulsed current modes is presented. Comparison of experimental data on the structural properties of deposits with the results of model calculations indicates the adequacy of the model. To describe the features of the dendritic deposit growth and to determine the duration of the homogeneous structure formation in pulsed modes, the concept of critical thickness is introduced, at which a sharp change in the loose deposit density occurs. The dependence of the zinc deposit critical thickness on the pulse duty ratio under pulsed current modes is determined. The increasing of the pulse duty ratio leads to denser deposits with rounded dendrite shapes and fewer growth points, as compared with the deposit obtained in galvanostatic mode. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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4. Heating Dynamics of the Active Region of High-Power Semiconductor Lasers (λ = 1060 nm) with an Ultra-Wide Aperture (800 µm) in the Quasi-CW Mode.
- Author
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Shashkin, I. S., Rybkin, A. D., Kryuchkov, V. A., Kazakova, A. E., Romanovich, D. N., Rudova, N. A., Slipchenko, S. O., and Pikhtin, N. A.
- Abstract
An approach is developed to study temporal behavior of the active region overheating in high-power semiconductor lasers (λ = 1060 nm) with an ultrawide aperture (800 μm) operating in a quasi-continuous regime of pumping by current pulses with an amplitude of 21 A, a duration of 1 ms, and a repetition rate of 10 Hz. The approach is based on measuring the lasing dynamics with spectral selection. The lasing spectrum analysis shows that the region of the rising edge, where the amplitude of the current pulse increases, is characterized by a maximum red-shift rate of 30 nm ms
–1 , which is due to both thermal and nonthermal effects. The pulse region corresponding to a constant pump current amplitude is characterized only by a thermal red shift of the lasing spectrum long-wavelength edge at a rate of ~1 nm ms–1 . The obtained experimental active region overheating is 2.78°C for the constant pump current amplitude range, which agrees with the calculated overheating of 3.08°C for the pump conditions under study. [ABSTRACT FROM AUTHOR]- Published
- 2023
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5. Phonophoresis treatment of subacromial impingement syndrome: Pulsed or continuous: A randomized-controlled clinical trial.
- Author
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Kelle, Bayram, Deniz, Volkan, and Ortaç, Emine Aygül
- Abstract
Objectives: This study aims to compare the effectiveness of pulsed and continuous modes of therapeutic ultrasound (US) for phonophoresis in the treatment of subacromial impingement syndrome (SAIS). Patients and methods: Between April 2019 and January 2021, a total of 66 patients with SAIS (17 males, 49 females; mean age: 48.2±8.6 years; range, 19 to 64 years) were included. The patients were randomized to the phonophoresis with continuous mode group (n=22), phonophoresis with pulsed mode group (n=22), and phonophoresis with sham US group (n=22). Five grams of ibuprofen phonophoresis was applied in five sessions per week for three weeks for all groups. Primary outcomes were pain intensity as assessed by the Visual Analog Scale (VAS) and shoulder functions by the short version of Disabilities of the Arm, Shoulder and Hand Questionnaire (QuickDASH). The secondary outcome was the quality of life as assessed by the Nottingham Health Profile (NHP). All patients were evaluated at pre-treatment, post-treatment, and at three months after the end of the treatment. Results: There was a significant improvement in pain during activity, shoulder function, and quality of life after treatment in phonophoresis with continuous and pulsed modes compared to phonophoresis with sham US (p<0.05). Phonophoresis with continuous mode was superior to other groups in reducing pain at rest (p<0.05). Changes between pre-treatment and the three-month follow-up showed a significant improvement in pain during activity and shoulder functions in phonophoresis with continuous and pulsed modes, compared to phonophoresis with sham US (p<0.05). Phonophoresis with pulsed mode was more effective than the other interventions in improving quality of life during the same period (p<0.05). Conclusion: Despite a significant change in phonophoresis with continuous and pulsed modes, it is more pronounced for rest pain in the early period in continuous mode and for quality of life during follow-up in pulsed mode. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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6. On the Dynamics of the Development and the Results of the Action of Electric Discharge in an Aquatic Environment.
- Author
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Khlyustova, A. V., Sirotkin, N. A., Agafonov, A. V., Stepovich, M. A., and Shipko, M. N.
- Abstract
The properties of synthesized nanostructured materials are determined by the methods of their preparation. The combination of electric discharges with liquid is a new tool for the synthesis of pure structures but the conditions for obtaining structures play an important role as in the case of traditional synthesis methods. In this work, the electrical and emission characteristics of a low-temperature direct-current plasma in contact with water at currents of 0.25 and 0.80 A are studied. The values of the power (energy) of single discharges are calculated. It is established that this type of discharge burns in the pulsed mode. The value of the discharge current affects the frequency of occurrence of discharges and the energy of a single discharge. It is shown that low-temperature underwater plasma is an effective tool for the synthesis of nanocomposites based on metal oxides, the precursors of which are metal electrodes. The emission spectroscopy method is used to study the emission spectra of underwater plasma. The sputtering of electrodes during plasma combustion is established. X-ray phase analysis shows that the phase composition of the resulting products is determined by the strength of the plasma current. The formation of oxides and hydroxides of Ni and Cr with different valences of metal ions is found. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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7. ТЕХНОЛОГІЇ РЕМОНТУ КАТОДНОГО ВУЗЛА ЕЛЕКТРОН- НО-ПРОМЕНЕВОЇ ГАРМАТИ ІЗ ЗАСТОСУВАННЯМ ЕЛЕК- ТРОННО-ПРОМЕНЕВОГО ЗВАРЮВАННЯ.
- Author
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Загорніков, В. І., Нестеренков, В. М., Орса, Ю. В., and Ігнатенко, А. М.
- Subjects
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WELDING defects , *ELECTRON beam welding , *BRAZING , *BRAZED joints , *WELDING , *ELECTRON gun , *ELECTRON beams - Abstract
The elements of repair technology of electron beam welding in the manufacture of a metal-ceramic cathode unit of a powerful welding electron beam gun are considered. A low degree of heat generation at the place of weld overlapping inherent in electron beam welding reduces the risk of buckling parts being joined and provides the maximum compliance with the required sizes of the unit. The need in repair of the cathode unit was determined by the cases of supplying imported insulators with defects in the form of deviations of a thickness from 0.5 to 1.0 mm in the wall of the metal flange («collar») in the brazed joint with the insulator. It was necessary to eliminate the consequences of a violation of the mechanical treatment of the insulator collar after brazing. The possible ways and schemes of repair technologies of such units are shown that allow avoiding the rejection of valuable parts and transferring them to the category of those subjected to restoration. The presented repair technologies involve the use of circumferential insertsbandages of different configuration for two variants to eliminate welding defects associated both with local repair of the edge as well as with repair of its quite elongated areas. Due to a correct choice of the shape of repair inserts, the use of some technological methods and observance of the accuracy of assembly and the sequence of repair welding, it became possible to preserve geometric dimensions and to ensure the functionality of the welded assembly as a whole. 6 Ref., 6 Tabl., 6 Fig. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
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8. TECHNOLOGIES OF REPAIRING CATHODE UNIT OF ELECTRON BEAM GUN WITH THE USE OF ELECTRON BEAM WELDING.
- Author
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Zagornikov, V. I., Nesterenkov, V. M., Orsa, Yu. V., and Ignatenko, A. M.
- Subjects
ELECTRON beam welding ,ELECTRON gun ,WELDING defects ,ELECTRON beams ,CATHODES ,BRAZING ,BRAZED joints - Abstract
The elements of repair technology of electron beam welding in the manufacture of a metal-ceramic cathode unit of a powerful welding electron beam gun are considered. A low degree of heat generation at the place of weld overlapping inherent in electron beam welding reduces the risk of buckling parts being joined and provides the maximum compliance with the required sizes of the unit. The need in repair of the cathode unit was determined by the cases of supplying imported insulators with defects in the form of deviations of a thickness from 0.5 to 1.0 mm in the wall of the metal flange ("collar") in the brazed joint with the insulator. It was necessary to eliminate the consequences of a violation of the mechanical treatment of the insulator collar after brazing. The possible ways and schemes of repair technologies of such units are shown that allow avoiding the rejection of valuable parts and transferring them to the category of those subjected to restoration. The presented repair technologies involve the use of circumferential inserts-bandages of different configuration for two variants to eliminate welding defects associated both with local repair of the edge as well as with repair of its quite elongated areas. Due to a correct choice of the shape of repair inserts, the use of some technological methods and observance of the accuracy of assembly and the sequence of repair welding, it became possible to preserve geometric dimensions and to ensure the functionality of the welded assembly as a whole. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
9. UV-LED TECHNOLOGY: THE FUTURE OF SAFE AND SUSTAINABLE WATER DISINFECTION.
- Author
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Ångbäck, Ida, Persson, Kenneth M., and Paul, Catherine
- Subjects
LIGHT emitting diodes ,SUSTAINABILITY ,DRINKING water ,WATER disinfection - Abstract
Copyright of Vatten is the property of Foreningen Vatten and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2021
10. Working process calculation of the control circuit for pulsed operation regime of the MPD accelerator
- Author
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Tashayev, Yuriy
- Subjects
discharge current ,pulse shape ,Morgan scheme ,дискретные плазменные образования ,pulsed mode ,плазменные ускорители ,схема Моргана ,plasma accelerators ,discrete plasma formations ,импульсный режим ,разрядный ток ,форма импульса - Abstract
A circuit for controlling the discharge current of an MPD accelerator based on the Morgan circuit is considered. It is shown that theoretically operation regime of the accelerator, depending on the parameters of the circuit, can be stationary, modulation, and pulsed. The necessary condition for the accelerator operation in the periodic mode is established. Calculations of the pulse shape of the discharge current are carried out. The experimentally observed pulse forms are compared with the calculated ones., Рассмотрена схема управления током разряда МПД-ускорителя, основанная на схеме Моргана. Теоретически показано, что режим работы ускорителя в зависимости от параметров схемы может быть стационарным, модуляционным и импульсным. Найдено необходимое условие работы ускорителя в периодическом режиме. Проведены расчеты формы импульса разрядного тока. Найдено условие перехода от модуляционного режима к импульсному. Экспериментально наблюдаемые формы импульсов сравниваются с расчетными.
- Published
- 2023
- Full Text
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11. Processes of formation of iron oxide nanoparticles by pulse modulation of RF discharge at atmospheric pressure
- Subjects
pulsed mode ,наноÑаÑÑиÑÑ Ð¾ÐºÑида железа ,iron oxide nanoparticles ,вÑÑокоÑаÑÑоÑÐ½Ð°Ñ Ð¿Ð»Ð°Ð·Ð¼Ð° ,плазмоакÑивиÑÑемое Ñ Ð¸Ð¼Ð¸ÑеÑкое оÑаждение из газовой ÑÐ°Ð·Ñ ,plasma-assisted chemical vapor deposition ,импÑлÑÑнÑй Ñежим ,high-frequency plasma - Abstract
УникалÑнÑе Ñ Ð°ÑакÑеÑиÑÑики наноÑаÑÑÐ¸Ñ Ð¾ÐºÑида железа делаÑÑ Ð¸Ñ Ð¿ÑивлекаÑелÑнÑми Ð´Ð»Ñ Ð¸ÑÑледований в ÑазлиÑнÑÑ Ð¾Ð±Ð»Ð°ÑÑÑÑ , ÑÐ°ÐºÐ¸Ñ ÐºÐ°Ðº биомедиÑина, ÑлекÑÑоÑÐµÑ Ð½Ð¸ÐºÐ°, ÑвÑÐ·Ñ Ð¸ дÑ. ÐÐ»Ð°Ð·Ð¼Ð¾Ñ Ð¸Ð¼Ð¸ÑеÑкое оÑаждение из газовой ÑÐ°Ð·Ñ Ð¾Ð´Ð¸Ð½ из вÑÑокоÑÑÑекÑивнÑÑ ÑпоÑобов ÑинÑеза наноÑаÑÑиÑ, позволÑÑÑий на недоÑогом обоÑÑдовании полÑÑаÑÑ ÑаÑÑиÑÑ Ð·Ð°Ð´Ð°Ð½Ð½Ð¾Ð³Ð¾ ÑазмеÑа как в лабоÑаÑоÑнÑÑ ÑÑловиÑÑ , Ñак и в пÑомÑÑленнÑÑ Ð¼Ð°ÑÑÑÐ°Ð±Ð°Ñ Ñ Ð²ÑÑокой ÑкоÑоÑÑÑÑ Ð¾ÑÐ°Ð¶Ð´ÐµÐ½Ð¸Ñ Ð¼Ð°ÑеÑиала.Ð ÑабоÑе бÑли полÑÑÐµÐ½Ñ Ð½Ð°Ð½Ð¾ÑаÑÑиÑÑ Ð² ÑазлиÑнÑÑ ÑÐµÐ¶Ð¸Ð¼Ð°Ñ ÑабоÑÑ ÑкÑпеÑименÑалÑной ÑÑÑановки меÑодом Ð¿Ð»Ð°Ð·Ð¼Ð¾Ñ Ð¸Ð¼Ð¸ÑеÑкого оÑÐ°Ð¶Ð´ÐµÐ½Ð¸Ñ Ð¸Ð· газовой ÑазÑ. ÐÑоанализиÑован ÑоÑÑав ÑаÑÑÐ¸Ñ Ð¼ÐµÑодом ÐРФÑÑÑе-ÑпекÑÑоÑкопии, подÑвеÑдилоÑÑ Ð½Ð°Ð»Ð¸Ñие окÑидов железа (FeO, Fe2O3 и Fe3O4). ÐÑл пÑоведÑн ÑенÑгеноÑÑÑÑкÑÑÑнÑй анализ вÑÑвивÑий налиÑие в обÑазÑÐ°Ñ Ð¿ÑимеÑей, в пеÑвÑÑ Ð¾ÑеÑÐµÐ´Ñ ÑглеÑода и его окÑидов.ÐÑоизведÑн анализ ÑÑÐµÑ Ð¸Ð¾Ð¼ÐµÑÑиÑеÑкого ÑоÑÑава, а Ñакже оÑенка ÑаÑпÑÐµÐ´ÐµÐ»ÐµÐ½Ð¸Ñ ÑазмеÑов наноÑаÑÑÐ¸Ñ Ð¿Ð¾ ÑезÑлÑÑаÑам анализа изобÑажений ÑканиÑÑÑÑей ÑлекÑÑонной микÑоÑкопии. РезÑлÑÑаÑÑ Ð¿Ð¾Ð·Ð²Ð¾Ð»ÑÑÑ ÑооÑнеÑÑи влиÑние Ñежимов оÑÐ°Ð¶Ð´ÐµÐ½Ð¸Ñ Ð½Ð° ÑкоÑоÑÑÑ ÑоÑÑа и ÑÑаÑиÑÑиÑеÑкое ÑаÑпÑеделение по ÑазмеÑам наноÑаÑÑÐ¸Ñ Ð¾ÐºÑидов железа., The unique characteristics of iron oxide nanoparticles make them attractive for research in various fields, such as biomedicine, electrical engineering, communications, and others. Plasma-enhanced chemical vapor deposition is one of the highly efficient methods for the synthesis of nanoparticles, which makes it possible to obtain particles of a given size on inexpensive equipment both in laboratory conditions and on an industrial scale with a high material deposition rate.In the work, nanoparticles were obtained in various modes of operation of the experimental setup by plasma-enhanced chemical vapor deposition from the gas phase. The composition of the particles was analyzed by FTIR spectroscopy, and the presence of iron oxides (FeO, Fe2O3 and Fe3O4) was confirmed. X-ray diffraction analysis was carried out, which revealed the presence of impurities in the samples, primarily carbon and its oxides.In this work, an analysis of the stoichiometric composition was made, as well as an assessment of the size distribution of nanoparticles based on the results of the analysis of images of scanning electron microscopy. The results allow us to correlate the effect of deposition modes on the growth rate and the statistical size distribution of iron oxide nanoparticles.
- Published
- 2022
- Full Text
- View/download PDF
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