480 results on '"Pulsed mode"'
Search Results
2. Membrane free alkaline sono-electrolysis for hydrogen production: An experimental approach.
- Author
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Merabet, Nour Hane and Kerboua, Kaouther
- Subjects
- *
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
- View/download PDF
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.
- Subjects
- *
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
- Full Text
- View/download PDF
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
- Full Text
- View/download PDF
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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- View/download PDF
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
- *
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. Laboratory and Numerical Study of the Peculiarities of Sea Surface Cooling in Coastal Waters.
- Author
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Kupriyanova, A. E. and Gritsenko, V. A.
- Subjects
- *
TERRITORIAL waters , *SALINE waters , *CHEMICAL stability , *BUOYANCY , *SEAWATER - Abstract
The initial phases of penetration of cold waters from the sea surface into the depth are analyzed within a study of the process of sea surface cooling. The phases of immersion of small volumes of water with negative buoyancy, reaching the bottom, and propagation along the bottom slope have been studied in laboratory experiment and numerical simulation. The interaction between two small volumes of salt water, which sequentially originate in the surface freshwater layer, during their immersion and subsequent propagation along the bottom slope is described in detail. Laboratory experiments have shown that the second of two water spots, equal in volumes and negative buoyancy, always reaches the first one during propagation along the bottom slope. A phenomenological explanation of this fact is suggested. The images of individual phases of the water-spot propagation show quite long-term stability of laminar structure of tracers inside the water spots. The simulation allows distinguishing two characteristic phases (advective and viscous) of interaction between two water spots. The experimental and simulation results allow us to suggest the general scheme of the negative-buoyancy water dynamics in coastal waters. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
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11. DEFINITION OF THE INFLUENCE OF PULSED DEPOSITION MODES ON THE ELECTROCHROMIC PROPERTIES OF Ni(OH)2- POLYVINYL ALCOHOL FILMS.
- Author
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Kotok, Valerii and Kovalenko, Vadym
- Subjects
GLASS coatings ,OXIDE coating ,POLYVINYL alcohol ,DENSITY currents ,CURRENT distribution ,ELECTRIC power consumption - Abstract
In this work, the influence of some types of the pulsed deposition mode of electrochromic films from aqueous solutions of nickel nitrate with the addition of polyvinyl alcohol was investigated. Glass coated with a fluorine-doped tin oxide film was used as the basis for deposition. The deposition of nickel (II) hydroxide – polyvinyl alcohol electrochromic films was carried out in three pulsed modes: –0.2 mA/cm²×5 s, 0 mA cm²×5 s (10 minutes); –0.5 mA/cm²×2 s, 0 mA/cm²×8 s (10 minutes); –1 mA/cm²×1 s, 0 mA/cm²×9 s. In this case, the amount of electricity used for the formation of thin-film electrodes was the same for all samples. The resulting films showed dramatic differences in electrochemical, optical, and quality characteristics. The sample obtained in the mode of the highest cathode current density and the duration of the no-current condition (1 mA/cm²×1 s, 0 mA/cm²×9 s) had the worst specific capacity and optical characteristics. This sample was characterized by the highest number of coating defects and color non-uniformity as well. The sample, which was obtained at average current densities (–0.5 mA/cm²×2 s, 0 mA/cm²×8 s), had the highest specific characteristics among the electrodes in the series. The coating was uniform and solid. Also, this sample had the greatest stability of the coloration depth value, which varied from 79.1 to 78.1 % (first to fifth cycles). The sample obtained in the mode –0.2 mA/cm²×5 s, 0 mA/cm²×5 s showed moderate specific indicators, however, there were some coating defects. According to the results obtained, a mechanism was proposed that explained the differences in the characteristics of thin-film electrodes formed in different modes. This mechanism consists of changing the time of non-stationary processes and the distribution of the current density with a change in the value of the deposition current density, the duration of the cathode period, and the no-current condition. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
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12. Optimization of pulsed-mode ultrasound assisted extraction of bioactive compounds from pomegranate peel using response surface methodology.
- Author
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Kumar, Ankit and Srinivasa Rao, Pavuluri
- Subjects
BIOACTIVE compounds ,EXTRACTION (Chemistry) ,POMEGRANATE ,FLAVONOIDS ,PHENOLS - Abstract
In this study, a pulsed mode ultrasound assisted extraction was performed for the extraction of bioactive compounds from Pomegranate (Punica granatum L.) peel. Box-Behnken experimental design combined with response surface methodology, was applied for the optimization of process conditions. The independent variables investigated were ultrasound amplitude (50–80%), sonication time (5–15 min), duty cycle (0.2–0.8), and methanol concentration (30–70%) to maximize the yield of total phenolic content, flavonoid content, total condensed and hydrolysable tannin (TCT and THT respectively), and antioxidant activity (DPPH and FRAP). The experimental results were fitted to quadratic models, and statistical analysis in terms of multiple regression, and analysis of variation was carried out for each response variable. The optimum predicted values of the response variables were obtained at 70% methanol concentration, 12.8 min of sonication treatment at a duty cycle of 0.58, and 80% ultrasound amplitude. A comparative analysis at optimized condition showed better recovery of bioactive compounds in pulsed mode, compared to continuous mode of sonication. Correlation analysis of the response variables was done to find the associations among the variables. Multivariate analysis using principal component analysis, and hierarchical cluster analysis was done for better understanding of interactions among experimental treatments and responses. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
13. ENVELOPE FLUCTUATIONS DISTRIBUTION OF SIMPLE RADAR PULSE BACKSCATTERING IN RARIFIED MEDIUM
- Author
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D. A. Denisenkov, A. G. Gorelik, and S. F. Kolomietc
- Subjects
radar ,pulsed mode ,rarified medium ,kerr-rice model ,radar meteorology ,Motor vehicles. Aeronautics. Astronautics ,TL1-4050 - Abstract
The basis of modern radar techniques is the direct use of radio-physical data on the power of backscattering. At the same time, the data volume received from the radar allows us to form new estimates and essentially specify classical ones. Significant steps have been made in this direction, using, for example, phase (Doppler) methods. The "modified Rayleigh model" used in radar meteorology to form a scattered field on rarefied medium particles is called the Kerr-Rice model. The main advantage of the Rayleigh model is its simplicity. But it itself contains a deep contradiction, consisting in its logical completion. Based on the statistics study of the first distribution in the rains of varying intensity the authors on a large statistical material have determined the fact of their not Rayleigh form and extreme stability of the latter in relation to natural changes of precipitation intensity. The first distribution is different from the theoretically expected one in the Kerr-Rice model, which makes it possible to use linear-logarithmic detection. It is concluded that the width and the mean of the spectrum of the same signal have the expected dynamics with respect to changes in precipitation intensity and dynamic processes in them. Tables with experimental data are presented. Two main distribution models are considered: lognormal and "logo-gamma-functional". It is concluded that, despite the absence of qualitative differences, the difference in the form of the distributions obtained with different equipment can be a natural consequence of significant discrepancies in the peak power and / or the width of the antenna pattern. The graphs of the first experimental distributions of envelope fluctuations on a linear and semi-logarithmic scale are presented.
- Published
- 2018
- Full Text
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14. Stability of Ion Flow and Role of Boundary Conditions in a Simplified Model of the E × B Plasma Accelerator with a Uniform Electron Mobility.
- Author
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Romadanov, I. V., Smolyakov, A. I., Sorokina, E. A., Andreev, V. V., and Marusov, N. A.
- Abstract
Resistive oscillations of axial plasma with ionization effects are analyzed in configuration similar to the Hall effect thrusters. From analysis of stationary equations we have identified different types of the steady-state plasma flow profiles and use these solutions as initial conditions in time-dependent initial value simulations. We have identified unstable regimes with intrinsic oscillations, as well as stable regions without oscillations. It was found that nonlinear oscillations may exist in different form depending on the range of plasma parameters. Single mode coherent, multi-mode with nonlinear harmonics, and incoherent (stochastic) mode regimes were identified. We have further investigated the role of boundary conditions on the characteristics of nonlinear oscillations. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
15. ОСОБЛИВОСТІ ЗАСТОСУВАННЯ ЕЛЕКТРОННО-ПРОМЕНЕВОГО ЗВАРЮВАНЯ ПРИ ВИГОТОВЛЕННІ КАТОДНОГО ВУЗЛА ЕЛЕКТРОННОЇ ГАРМАТИ
- Author
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Нестеренков, В. М., Загорніков, В. І., Орса, Ю. В., and Ігнатенко, О. М.
- Abstract
The efficiency of using electron beam welding in producing dissimilar joints of structural materials of all thicknesses and shapes is well-known. The work for the first time considers the possibility of using electron beam welding for the production of high-precision parts of optical system in cathode unit, providing the necessary parameters and their joining with electron beam gun insulator in future. The use of electron beam welding at the final stage of manufacturing cathode unit opens the opportunity of minimizing the number of further technological operations. It is noted that to create the welding technology, in which the operation of welding would become a final assembly operation, the development of new designs of welded joints and schemes for assembly of cathode unit are required. Due to a correct design of welding units and compliance with the accuracy of assembling for welding, it became possible to preserve geometric dimensions after electron beam welding and to provide the operational reliability of the design as a whole. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
16. FEATURES OF APPLYING ELECTRON BEAM WELDING IN MANUFACTURE OF THE CATHODE ASSEMBLY OF THE ELECTRON GUN.
- Author
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Nesterenkov, V. M., Zagornikov, V. I., Orsa, Yu. V., and Ignatenko, O. M.
- Subjects
ELECTRON beam welding ,ELECTRON beams ,ELECTRON gun ,WELDED joints ,MANUFACTURING processes ,CONSTRUCTION materials - Abstract
The efficiency of using electron beam welding in producing permanent joints of structural materials of all thicknesses and shapes is well-known. The work for the first time considers the possibility of using electron beam welding for the production of high-precision parts of optical system in cathode unit, providing the necessary parameters and their joining with electron beam gun insulator in future. The use of electron beam welding at the final stage of manufacturing cathode unit opens the opportunity of minimizing the number of further technological operations. It is noted that to create the welding technology, in which the operation of welding would become a final assembly operation, the development of new designs of welded joints and schemes for assembly of cathode unit are required. Due to a correct design of welding units and compliance with the accuracy of assembling for welding, it became possible to preserve geometric dimensions after electron beam welding and to provide the operational reliability of the design as a whole. 5 Ref., 6 Figures. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
17. A Study on the Stability of Water-Gated Organic Field-Effect-Transistors Based on a Commercial p-Type Polymer
- Author
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Rosaria Anna Picca, Kyriaki Manoli, Eleonora Macchia, Angelo Tricase, Cinzia Di Franco, Gaetano Scamarcio, Nicola Cioffi, and Luisa Torsi
- Subjects
poly-3-hexylthiophene ,electrolyte-gated OFET ,degradation ,pulsed mode ,biosensors ,Chemistry ,QD1-999 - Abstract
Robust electrolyte-gated organic field-effect-transistors (OFETs) are particularly needed for the development of biosensing devices. However, when a FET biosensor operates in aqueous environments or even in real biological fluids, some critical issues may arise due to the possible lack of environmental long-term and/or operational stability. An important source of instability is associated with the degradation of the organic electronic channel materials such as for instance, poly-3-hexylthiophene (P3HT), a benchmark commercially available p-type organic semiconductor. In this work, the investigation of critical parameters, such as the control over spurious electrochemical phenomena as well as the operating conditions that can affect water-gated OFETs lifetime, is reported, together with a proposed modeling of the P3HT stability curve over 1 week in water. The investigation of possible morphological/chemical modifications occurring at the polymer surface after operating in water for 2 weeks was carried out. Moreover, it is proven how the addition of a gel layer can extend the P3HT based water-gated OFET shelf life up to 2 months.
- Published
- 2019
- Full Text
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18. 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
- View/download PDF
19. Biopsy of oral soft tissue lesions by 808 nm and 980 nm diode laser: a morphological and histochemical evaluation
- Author
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Kaajal Gill, Rajat Bhandari, Neerja Sethi, and Simarpreet V Sandhu
- Subjects
Materials science ,medicine.diagnostic_test ,business.industry ,Mean value ,Soft tissue ,Connective tissue ,Orthodontics ,Laser ,law.invention ,medicine.anatomical_structure ,law ,Biopsy ,medicine ,Periodontics ,Pulsed mode ,Dentistry (miscellaneous) ,Thermal damage ,Oral Surgery ,Nuclear medicine ,business ,Diode - Abstract
Laser-induced thermal damage and corresponding histological artefacts interfere with accurate histological interpretation, thus hampering the judgment of given pathology and creating a dilemma about the effectiveness of lasers as a bioptic tool. The objective of the present study was to compare macroscopic and microscopic (morphometric, pathomorphological and histochemical) characteristics of biopsies procured by scalpel and two diode laser systems (808 nm and 980 nm) Study was conducted on 105 patients (81 male, 24 female; mean SD age 42 years) who were randomly divided into three groups (808 nm diode laser, 980 nm diode laser and scalpel) with 35 patients each. A total of 525 sections of 5 μm thickness were obtained from 105 formalin-fixed paraffin-embedded blocks. A total of 315 sections were stained using H&E for evaluation of morphometric (LTD) and pathomorphological changes (epithelial, connective tissue, vascular and cytological). PAS and Giemsa special stains were used for the evaluation of glycogen content and assessment of inflammation in 105 sections. The 808 nm DL at 2.5W continuous wave (cw) and 980 nm DL at 5W pulsed mode (pm) showed charring in 48% and 31% of samples respectively, while there was no charring in the scalpel group. Mean value of LTD in 808 nm DL group at cw was found to be five times higher than that produced in 980 nm DL group at pm. The 808 nm DL produced higher number of pathomorphological artefacts compared to the other two study groups (980 nm DL, scalpel group). On histochemical evaluation, majority of PAS stained sections showed uniform distribution in scalpel group, while 60% sections in 980 nm DL group and 54.2% sections in 808 nm DL showed patchy distribution.80% of Giemsa-stained sections revealed dense inflammation in scalpel group, 54.2% showed less dense in 808 nm DL group and inflammation was absent in 34.2% sections in 980 nm DL group. The 980 nm diode laser proved to be an effective and preferred bioptic tool over the 808 nm diode laser.
- Published
- 2021
20. Effect of Parameters of Pulsed Potential Mode on Concentration Changes in the Bulk Loose Zinc Deposit and Its Properties.
- Author
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Nikitin, V. S., Ostanina, T. N., and Rudoi, V. M.
- Subjects
- *
ZINC , *CRYSTAL growth , *ANODES , *CATHODES , *DENDRITIC crystals , *ELECTROLYSIS - Abstract
It is shown that the parameters of pulsed potential modes (pulse-on and pulse-off times) have a pronounced effect on the growth dynamics and properties of loose metal deposits in the cases that the process proceeds under the conditions of non-steady-state diffusion. It is proposed to use a ratio between the cathodic and anodic charges in a cycle as a parameter that characterizes the concentration changes. By varying the parameters of pulsed potential, zinc deposits of various morphology can be obtained: from compact deposits to highly porous deposits that consist of branched dendritic particles. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
21. Influence of the Design Features of a Piezoelectric Transducer on Probing Signal Duration.
- Author
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Konovalov, R. S., Konovalov, S. I., and Kuz’menko, A. G.
- Subjects
- *
PIEZOELECTRIC transducers , *MICROELECTROMECHANICAL systems - Abstract
A piezoelectric transducer in the form of a damped plate radiating into steel through a system of transition layers is considered. The algorithm for calculating the frequency response of the transducer is described, and its pulsed operation mode is investigated. A voltage pulse in the form of a half sine wave at the plate’s antiresonance frequency is selected as an electrical excitation signal. Some materials used for manufacturing certain transducer design elements are considered. Based on estimative calculations of the geometrical thicknesses of layers actually encountered in the practice of ultrasonic testing, their wave thicknesses are chosen. The data obtained is used to determine the shape of the emitter output signal. Calculations are carried out in a wide range of specific acoustic impedances of the wear plate. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
22. Nitriding of Stainless Steel in Electron-Beam Plasma in the Pulsed and DC Generation Modes.
- Author
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Gavrilov, N. V., Mamaev, A. S., and Chukin, A. V.
- Abstract
The influence of electron-beam parameters on the thickness and phase composition of a hardened layer formed upon the nitriding of austenitic stainless steel 12Cr18Ni10Ti in plasma produced by a beam in a low-pressure (3 Pa) nitrogen--argon mixture is studied. The results obtained in the DC and pulse-periodic modes of beam generation with the same mean current and electron energy are compared. In this case the negative bias voltage applied to the samples is 100 V. The nitriding temperature of 400°C is maintained at a mean beam current of 2.6 A and various combinations of frequency (100--500 Hz) and current pulse durations (0.1-0.3 ms) with an amplitude of 80 A. The mean ion-plasma current densities in the DC and pulsed modes are close in magnitude (2-3 mA/cm² at 400°C). The high pulsed ion-current density (35-70 mA/cm²) creates conditions under which the surface sputtering rate during the pulse exceeds the growth rate of the nitrided layer. The nitriding of steel in the pulsed and DC modes over four hours gives the same result. Hardened layers with a thickness of 7-8 µm and a microhardness of the surface component of 15 ± 1 GPa in which the main phase is a supersaturated nitrogen solid solution (expanded austenite) are formed. A possible explanation is that nitriding in an electron-beam plasma proceeds mainly under the action of long-lived active neutral nitrogen particles rather than as a result of ion bombardment. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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23. Definition of the influence of pulsed deposition modes on the electrochromic properties of Ni(OH)2-polyvinyl alcohol films
- Author
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Valerii Kotok and Vadym Kovalenko
- Subjects
Materials science ,pulsed mode ,nickel hydroxide ,Analytical chemistry ,Energy Engineering and Power Technology ,chemistry.chemical_element ,engineering.material ,composite coating ,Polyvinyl alcohol ,Industrial and Manufacturing Engineering ,law.invention ,chemistry.chemical_compound ,Coating ,law ,Management of Technology and Innovation ,electrochromism ,T1-995 ,Industry ,Electrical and Electronic Engineering ,Technology (General) ,Applied Mathematics ,Mechanical Engineering ,HD2321-4730.9 ,Cathode ,Computer Science Applications ,Nickel ,polyvinyl alcohol ,chemistry ,Control and Systems Engineering ,Electrochromism ,Electrode ,engineering ,electrodeposition ,Deposition (chemistry) ,Current density - Abstract
In this work, the influence of some types of the pulsed deposition mode of electrochromic films from aqueous solutions of nickel nitrate with the addition of polyvinyl alcohol was investigated. Glass coated with a fluorine-doped tin oxide film was used as the basis for deposition. The deposition of nickel (II) hydroxide – polyvinyl alcohol electrochromic films was carried out in three pulsed modes: –0.2mA/cm2×5s, 0mA/cm2×5s (10minutes); –0.5mA/cm2×2s, 0mA/cm2×8s (10minutes); –1mA/cm2×1s, 0mA/cm2×9s. In this case, the amount of electricity used for the formation of thin-film electrodes was the same for all samples. The resulting films showed dramatic differences in electrochemical, optical, and quality characteristics. The sample obtained in the mode of the highest cathode current density and the duration of the no-current condition (1mA/cm2×1s, 0mA/cm2×9s) had the worst specific capacity and optical characteristics. This sample was characterized by the highest number of coating defects and color non-uniformity as well. The sample, which was obtained at average current densities (–0.5mA/cm2×2s, 0mA/cm2×8s), had the highest specific characteristics among the electrodes in the series. The coating was uniform and solid. Also, this sample had the greatest stability of the coloration depth value, which varied from 79.1 to 78.1% (first to fifth cycles). The sample obtained in the mode –0.2mA/cm2×5s, 0mA/cm2×5s showed moderate specific indicators, however, there were some coating defects. According to the results obtained, a mechanism was proposed that explained the differences in the characteristics of thin-film electrodes formed in different modes. This mechanism consists of changing the time of non-stationary processes and the distribution of the current density with a change in the value of the deposition current density, the duration of the cathode period, and the no-current condition.
- Published
- 2021
24. Reasons to go for thulium-based anatomical endoscopic enucleation of the prostate
- Author
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Thorsten Bach, Giorgio Bozzini, Christopher Netsch, A. J. Gross, Thomas R. W. Herrmann, Dmitry Enikeev, and Benedikt Becker
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Male ,Laser surgery ,medicine.medical_specialty ,Urology ,medicine.medical_treatment ,Enucleation ,Prostatic Hyperplasia ,030232 urology & nephrology ,chemistry.chemical_element ,Lasers, Solid-State ,Thulium laser ,law.invention ,03 medical and health sciences ,0302 clinical medicine ,Prostate ,law ,medicine ,Humans ,Prostatectomy ,business.industry ,Endoscopy ,Laser ,Prostatic enlargement ,Thulium ,medicine.anatomical_structure ,chemistry ,030220 oncology & carcinogenesis ,Pulsed mode ,Radiology ,business - Abstract
To summarize the current evidence and the reasons to go for thulium-based anatomical endoscopic enucleation of the prostate (AEEP). This review discusses the available literature on thulium-based AEEP. Thulium lasers operate at a wavelength between 1940 and 2013 nm. This wavelength, which has a low penetration depth in water, allows to perform smooth cuts in the prostatic tissue and allows urologists to perform various procedures: resection, vaporization, enucleation, or vapoenucleation of the prostate. Depending on the type of thulium laser, it can be used either in a continuous, or pulsed mode. In recent years, an increasing amount of evidence has described the thulium laser as a minimally invasive and size-independent treatment option for benign prostatic enlargement with excellent long-term results.
- Published
- 2021
25. Effect of Gallium Arsenide Charge Carrier Life Time on the Generation and Detection Efficiency of Continuous and Pulsed Terahertz Radiation
- Author
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I. Kolesnikova, R. A. Redkin, A. V. Tyazhev, and D. A. Kobtsev
- Subjects
Materials science ,фотопроводящие дипольные антенны ,Terahertz radiation ,Physics::Optics ,General Physics and Astronomy ,терагерцовое излучение ,01 natural sciences ,law.invention ,Gallium arsenide ,арсенид галлия ,Condensed Matter::Materials Science ,chemistry.chemical_compound ,law ,0103 physical sciences ,Dipole antenna ,время жизни носителей заряда ,010302 applied physics ,Condensed Matter::Other ,010308 nuclear & particles physics ,business.industry ,Photoconductivity ,Life time ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,chemistry ,Pulsed mode ,Optoelectronics ,Charge carrier ,business - Abstract
A configuration and test samples of photoconductive dipole antennas based on SI-GaAs:Cr and LT-GaAs for generation and detection of terahertz radiation are developed. Their operating characteristics in the pulsed mode and in the mode of operation as photomixers are experimentally investigated.
- Published
- 2021
26. Comparative efficacy of kneading massage and pulsed mode ultrasound in the management of chronic knee osteoarthritis
- Author
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Wasiu Abiodun Fatai and Adesola Ojo Ojoawo
- Subjects
musculoskeletal diseases ,medicine.medical_specialty ,Massage ,business.industry ,Ultrasound ,Physical therapy ,Medicine ,Pulsed mode ,Osteoarthritis ,business ,medicine.disease - Abstract
Introduction. Osteoarthritis of the knee is the most common presentation of osteoarthritis with prevalence between 12% and 35% of general population and is considered the leading cause of musculoskeletal disability in the elderly population worldwide. Aim. The study compared efficacy of kneading massage and pulsed ultrasound on pain, joint stiffness and difficulty in knee osteoarthritis (KOA). Material and methods. Fifty subjects with radiological evidence of KOA participated in the study. They were randomly allocated into kneading massage group (KMG) (25) and Ultrasound group (USG) (25). KMG received kneading massage for 7 minutes while USG received pulsed mode ultrasound for 15 minutes. Treatment was twice in a week for six weeks. Pain intensity (PI), joint stiffness and difficulty were assessed pre, 3rd and 6th weeks of treatment session with semantic differential scale and WOMAC. The data were analyzed using descriptive and inferential statistics, alpha level was set at 0.05 Results. There was a significant difference in present PI (F=11.45,P=0.001) and stiffness (F= 11.32, P=0.003) in USG. There was a significant reduction in PI (F=7.95, P=0.001) and joint stiffness (F=8.86, P=0.003) in KMG. At the 6th week, there was a significant differences in PI (t=12.23,P=0.000) and stiffness (t=8.08, P=0.000) when USG (3.00+0.4, vs 7.14+ 1.49) was compared with KMG (3.16+0.5 vs 7.50+1.5). Conclusion. Ultrasound (US) and kneading massage (KM) reduced PI and joint stiffness of KOA effectively; however US reduced PI than KM while KM reduces joint stiffness than US.
- Published
- 2021
27. Closure of skin incision by dual wavelength (980 and 1064 nm) laser application.
- Author
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Uba, Abdullahi Ibrahim, Tabakoglu, Haşim Ozgur, Abdullahi, Umar Aliyu, and Sani, Musbahu Muhammad
- Subjects
- *
SURGICAL site , *LASER therapy , *CONTINUOUS wave lasers , *LASER welding , *WOUND healing - Abstract
Thermal effect of dual wavelength (980 and 1064 nm) laser application in skin incision closure was assessed on 18 male and female Wister rats. 1-cm-long incisions were made on the shaved dorsal region of 220–250 g animals. The incisions were closed by laser irradiation at 1 W and exposure time, 5 seconds in continuous-wave mode (CW) and 1 W and exposure time, 10 seconds in pulsed mode to deliver total energies of 5 J and 10 J per spot onto the incisions, respectively. Animals from each group were sacrificed at 0th, 4th, and 7th days and the skin samples of the weld area were excised for histological analysis using Hematoxylin and Eosin (H & E) stain. Mean thermally altered area (TAA) of CW-mode laser-treated groups was found to increase significantly (p< 0.05) compared with pulsed mode laser treated group at 0th and 4th days post-irradiation while no significant difference (p> 0.05) was statistically found at 7th day post-irradiation. Moreover, tighter closure was observed with CW group at 7th day post-irradiation. We thus conclude that 1 W, 5 J for 5 seconds CW mode laser application of 980 and 1064 nm combined beam form in skin incision closure was found to have absolute wound healing capability with minimal thermal alteration.ABSTRACT FROM PUBLISHERCopyright of Journal of Cosmetic & Laser Therapy is the property of Taylor & Francis Ltd 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. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
28. InAs‐based quantum cascade lasers emitting close to 25 µm.
- Author
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Loghmari, Z., Bahriz, M., Meguekam, A., Teissier, R., and Baranov, A.N.
- Abstract
Indium arsenide (InAs)‐based quantum cascade lasers (QCLs) operating close to 25 µm are reported. Thick n‐doped InAs cladding layers were used for optical confinement. Fabry–Perot lasers exhibited a threshold current density as low as 1.1 kA/cm2 in pulsed mode at 80 K. The lasers operated in this regime up to 240 K, where the threshold current density increased up to 1.7 kA/cm2. These are the lowest threshold current densities for QCLs operating above 20 µm. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
29. Effects of phonophoresis with acetic acid in the treatment of calcific tendinitis of the shoulder: case report
- Author
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Heleodório Honorato dos Santos, Edilene Araújo Pamplona, and Andressa Medeiros Araújo
- Subjects
Right shoulder ,Therapeutic ultrasound ,Shoulders ,business.industry ,medicine.medical_treatment ,Calcific tendinitis ,medicine.disease ,Acetic acid ,chemistry.chemical_compound ,chemistry ,Anesthesia ,Statistical significance ,medicine ,Pulsed mode ,business ,Phonophoresis - Abstract
Background: The calcific tendinitis of the shoulder is a dysfunction conservatively treated by shock waves, iontophoresis, and phonophoresis, associated or not with the use of acetic acid. Objective: To check the effects of phonophoresis with acetic acid in the treatment of calcific tendinitis of the shoulder in resorption stage. Methods: Measurements of ROM, muscle strength and functionality of the shoulder (SPADI) were made pre and post-physiotherapeutic treatment. The treatment protocol consisted of 10 sessions of therapeutic ultrasound with acetic acid (frequency = 3 MHz; intensity = 1.4 W/cm2; pulsed mode of 1:4), for 10 minutes, 3 times a week. The data were analyzed using the SPSS software (20.0), through the Student’s t-test (paired) considering a significance level of 5%. Results: There was significant improvement regarding the ROM, muscle strength and functionality of the right shoulder (SPADI) comparing pre vs. post-treatment (P0.05), in the comparison between the shoulders (right X left) in the post-treatment. Conclusion: According to the results of this case study, the protocol used (10 sessions of therapeutic ultrasound + 5% acetic acid) was effective in the treatment of calcific tendinitis of shoulder, improving the ROM, muscle strength and functional capacity, in addition to eliminating the pain of the shoulder affected.
- Published
- 2020
30. Effect of layer-by-layer formation of ingot during electroslag remelting on the quality of its surface and solidification structure
- Author
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Igor Protokovilov, Vitaly Porokhonko, and Victor Shapovalov
- Subjects
Surface (mathematics) ,Materials science ,Fusion zone ,Mechanical Engineering ,Metallurgy ,Layer by layer ,Metals and Alloys ,law.invention ,Quality (physics) ,Mechanics of Materials ,law ,Materials Chemistry ,Pulsed mode ,Crystallization ,Ingot - Abstract
The article presents the results of experimental studies of the features of forming the side surface and the crystallization structure of steel ingots, produced by the method of electroslag remelti...
- Published
- 2020
31. 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
32. Performance optimization of water-jet assisted underwater laser cutting of AISI 304 stainless steel sheet.
- Author
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Mullick, Suvradip, Madhukar, Yuvraj K., Roy, Subhransu, and Nath, Ashish K.
- Subjects
- *
WATER jets , *UNDERWATER welding & cutting , *LASER beam cutting , *STAINLESS steel sheets , *ELECTRONIC modulation , *EXPERIMENTAL design - Abstract
Recent development of water-jet assisted underwater laser cutting has shown some advantages over the gas assisted underwater laser cutting, as it produces much less turbulence, gas bubble and aerosols, resulting in a more gentle process. However, this process has relatively low efficiency due to different losses in water. Scattering is reported to be a dominant loss mechanism, which depends on the growth of vapor layer at cut front and its removal by water-jet. Present study reports improvement in process efficiency by reducing the scattering loss using modulated laser power. Judicious control of laser pulse on- and off-time could improve process efficiency through restricting the vapor growth and its effective removal by water-jet within the laser on- and off-time, respectively. Effects of average laser power, duty cycle and modulation frequency on specific energy are studied to get an operating zone for maximum efficiency. Next, the variation in laser cut quality with different process parameters are studied within this operating zone using Design of experiment (DOE). Response surface methodology (RSM) is used by implementing three level Box-Behnken design to optimize the variation in cut quality, and to find out the optimal process parameters for desired quality. Various phenomena and material removal mechanism involved in this process are also discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
33. On some paradoxes in the analysis of pulsed operation mode of acoustic transducers by the method of integral transformations.
- Author
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Balabaev, S. and Ivina, N.
- Subjects
- *
ACOUSTIC transducers , *WAVENUMBER - Abstract
Reasons for the appearance of 'precursors' and 'tails' in the analysis of pulsed operation mode of acoustic transducers by the method of integral transformations are considered. It is emphasized that the reason is the impossibility to make an accurate allowance for the actual dependence of the complex wave number on frequency over the entire frequency range. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
34. Equipment for electric arc metallizing with pulsed discharge of the air-spraying jet.
- Author
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Royanov, V. A. and Bovikov, V. I.
- Subjects
ELECTRIC arc ,ELECTRIC discharges ,JETS (Fluid dynamics) ,DATA analysis ,ELECTRIC power consumption ,COMPRESSED air - Abstract
The results of a review of literature data show that electric arc metallizing systems are characterized by high consumption of compressed air. Spraying is accompanied by the high-intensity interaction of the spraying air jet with the liquid metal of the molten ends of the electrodes, leading to rapid burnout of the alloying elements. The intensity of the oxidation reaction depends on the heat resistance of the sprayed material, the dispersion of the particles, the affinity of the components for oxygen and the technological parameters of the coatings. In order to reduce the oxidation effect, it is proposed to use a pulsed air-spraying jet. To solve this problem, experiments were carried out to develop appropriate equipment for the EN-17 stationary electric arc metallizing system characterized by the pulsed discharge of the air-spraying jet in the range 0–130 Hz. The experimental results show that the spraying jet is pulsed with temporary breaks. When using circular cross sections, the pulse smoothly becomes larger. The application of the right-angled section results in the pulse shape increasing at a higher rate. The experimental results show that the oxidation effect of the air-spraying jet is reduced. It is also shown that the optimum frequency resulting in improved properties of the coating is in the range 40–80 Hz. [ABSTRACT FROM PUBLISHER]
- Published
- 2016
- Full Text
- View/download PDF
35. Определение влияния импульсных режимов осаждения на электрохромные свойства пленок Ni(OH)2-поливиниловый спирт
- Subjects
поливиниловый спирт ,электроосаждение ,pulsed mode ,nickel hydroxide ,композитное покрытие ,гидроксид никеля ,імпульсний режим ,композитне покриття ,composite coating ,електроосадження ,полівініловий спирт ,polyvinyl alcohol ,электрохромизм ,гідроксид нікелю ,electrodeposition ,electrochromism ,импульсный режим ,електрохромізм - Abstract
In this work, the influence of some types of the pulsed deposition mode of electrochromic films from aqueous solutions of nickel nitrate with the addition of polyvinyl alcohol was investigated. Glass coated with a fluorine-doped tin oxide film was used as the basis for deposition. The deposition of nickel (II) hydroxide – polyvinyl alcohol electrochromic films was carried out in three pulsed modes: –0.2 mA/cm2×5 s, 0 mA/cm2×5 s (10 minutes); –0.5 mA/cm2×2 s, 0 mA/cm2×8 s (10 minutes); –1 mA/cm2×1 s, 0 mA/cm2×9 s. In this case, the amount of electricity used for the formation of thin-film electrodes was the same for all samples. The resulting films showed dramatic differences in electrochemical, optical, and quality characteristics. The sample obtained in the mode of the highest cathode current density and the duration of the no-current condition (1 mA/cm2×1 s, 0 mA/cm2×9 s) had the worst specific capacity and optical characteristics. This sample was characterized by the highest number of coating defects and color non-uniformity as well. The sample, which was obtained at average current densities (–0.5 mA/cm2×2 s, 0 mA/cm2×8 s), had the highest specific characteristics among the electrodes in the series. The coating was uniform and solid. Also, this sample had the greatest stability of the coloration depth value, which varied from 79.1 to 78.1 % (first to fifth cycles). The sample obtained in the mode –0.2 mA/cm2×5 s, 0 mA/cm2×5 s showed moderate specific indicators, however, there were some coating defects. According to the results obtained, a mechanism was proposed that explained the differences in the characteristics of thin-film electrodes formed in different modes. This mechanism consists of changing the time of non-stationary processes and the distribution of the current density with a change in the value of the deposition current density, the duration of the cathode period, and the no-current condition., В работе было исследовано влияние некоторых режимов импульсного режима нанесения электрохромных пленок из водных растворов нитрата никеля с добавкой поливинилового спирта. В качестве основ для осаждения использовали стекло, покрытое пленкой оксида олова допированного фтором. Осаждение электрохромных пленок гидроксид никеля (II) – поливиниловый спирт было проведено в трех импульсных режимах: –0,2 мА/см2×5с, 0мА/см2 ×5с (10минут); –0,5мА/см2×2с, 0мА/см2×8с (10минут); –1мА/см2×1с, 0мА/см2×9с. При этом количество электричества, которое пошло на формирование тонкопленочных электродов было одинаковым для всех образцов. Полученные пленки показали кардинальные отличия в электрохимических, оптических и качественных характеристиках. Образец, полученный в режиме наибольшей катодной плотности тока и длительности бестоковой паузы (1мА/см2×1с, 0мА/см2×9с), имел наихудшие удельные емкостные и оптические характеристики. Также этот образец характеризовался наибольшим количеством дефектов покрытия и неравномерностью цвета. Образец, который был получен при средних плотностях токов (–0,5мА/см2×2с, 0мА/см2×8с), имел самые высокие удельные характеристики среди электродов серии. Покрытие было равномерное и сплошное. Также данный образец имел наибольшую стабильность величины глубины затемнения, которая менялась с 79,1 до 78,1% (первый-пятый циклы). Образец полученный в режиме –0,2мА/см2×5с, 0мА/см2×5 с продемонстрировал средние удельные показатели, однако при этом имели место дефекты покрытия. Согласно полученным результатам, был предположен механизм, который объясняет отличия характеристик тонкопленочных электродов, сформированных в разных режимах. Этот механизм заключается в изменении времени нестационарных процессов и распределении плотности тока при изменении величины плотности тока осаждения, длительности катодного периода и бестоковой паузы, Було досліджено вплив деяких режимів імпульсного режиму нанесення електрохромних плівок з водних розчинів нітрату нікелю з добавкою полівінілового спирту. У якості основи для осадження використовували скло, покрите плівкою оксиду олова допованого фтором. Осадження електрохромних плівок гідроксиду нікелю (II) – полівініловий спирт було проведено в трьох імпульсних режимах: –0,2мА/см2×5с, 0 мА/см2×5с (10хвилин); –0,5мА/см2×2с, 0мА/см2×8 з (10хвилин); –1мА/см2×1с, 0мА/см2×9с. При цьому кількість електрики, яка пішла на формування тонкоплівкових електродів, була однаковою для всіх зразків. Отримані плівки показали кардинальні відмінності в електрохімічних, оптичних і якісних характеристиках. Зразок, отриманий в режимі максимальної катодної густини струму і тривалості безструмової паузи (1мА/см2×1с, 0мА/см2×9с), мав найгірші питомі ємкісні і оптичні характеристики. Також цей зразок характеризувався найбільшою кількістю дефектів покриття і нерівномірністю кольору. Зразок, який був отриманий при середніх щільності струмів (–0,5мА/см2×2с, 0мА/см2×8с), мав найвищі питомі характеристики серед електродів серії. Покриття було рівномірне і суцільне. Також даний зразок мав найбільшу стабільність величини глибини затемнення, яка змінювалася з 79,1 до 78,1% (перший-п'ятий цикли). Зразок, отриманий в режимі –0,2мА/см2×5с, 0мА/см2×5с, продемонстрував середні питомі показники, однак при цьому мали місце дефекти покриття. Згідно з отриманими результатами, був припущений механізм, який пояснює відмінності характеристик тонкоплівкових електродів, сформованих в різних режимах. Цей механізм полягає в зміні часу нестаціонарних процесів і розподілі щільності струму при зміні величини густини струму осадження, тривалості катодного періоду і безструмової паузи
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- 2021
36. Using pulsed mode scanning electron microscopy for cathodoluminescence studies on hybrid perovskite films
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Rachel A. Oliver, Jordi Ferrer Orri, Stuart Macpherson, Elizabeth M. Tennyson, Giorgio Divitini, Gunnar Kusch, Caterina Ducati, Samuel D. Stranks, Ferrer Orri, Jordi [0000-0002-0432-5932], Tennyson, Beth [0000-0003-0071-8445], Kusch, Gunnar [0000-0003-2743-1022], Divitini, Giorgio [0000-0003-2775-610X], Macpherson, Stuart [0000-0003-3758-1198], Oliver, Rachel [0000-0003-0029-3993], Ducati, Caterina [0000-0003-3366-6442], Stranks, Samuel [0000-0002-8303-7292], Apollo - University of Cambridge Repository, Ferrer Orri, J [0000-0002-0432-5932], Tennyson, EM [0000-0003-0071-8445], Kusch, G [0000-0003-2743-1022], Divitini, G [0000-0003-2775-610X], Macpherson, S [0000-0003-3758-1198], Stranks, SD [0000-0002-8303-7292], Apollo-University Of Cambridge Repository, Tennyson, Elizabeth M [0000-0003-0071-8445], and Stranks, Samuel D [0000-0002-8303-7292]
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Paper ,Materials science ,Scanning electron microscope ,business.industry ,Focus on Cathodoluminescence and Electron Beam Induced Current of Semiconductor Nanostructures ,pulsed mode ,hyperspectral mapping ,hybrid perovskite ,Cathodoluminescence ,cathodoluminescence ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,7. Clean energy ,01 natural sciences ,0104 chemical sciences ,beam damage ,Optoelectronics ,Pulsed mode ,0210 nano-technology ,business ,Perovskite (structure) - Abstract
The use of pulsed mode scanning electron microscopy cathodoluminescence (CL) for both hyperspectral mapping and time-resolved measurements is found to be useful for the study of hybrid perovskite films, a class of ionic semiconductors that have been shown to be beam sensitive. A range of acquisition parameters is analysed, including beam current and beam mode (either continuous or pulsed operation), and their effect on the CL emission is discussed. Under optimized acquisition conditions, using a pulsed electron beam, the heterogeneity of the emission properties of hybrid perovskite films can be resolved via the acquisition of CL hyperspectral maps. These optimized parameters also enable the acquisition of time-resolved CL of polycrystalline films, showing significantly shorter lived charge carriers dynamics compared to the photoluminescence analogue, hinting at additional electron beam-specimen interactions to be further investigated. This work represents a promising step to investigate hybrid perovskite semiconductors at the nanoscale with CL.
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- 2021
37. Medical Applications of Diode Lasers: Pulsed versus Continuous Wave (cw) Regime
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Michał Stajnke, Tomasz Ochrymiuk, Jacek Szymańczyk, Michał Michalik, and Adam Cenian
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Materials science ,laryngology ,Article ,law.invention ,030207 dermatology & venereal diseases ,03 medical and health sciences ,laser diodes ,0302 clinical medicine ,law ,TJ1-1570 ,Mechanical engineering and machinery ,Electrical and Electronic Engineering ,030223 otorhinolaryngology ,Diode ,business.industry ,medical applications ,Mechanical Engineering ,Laser ,dermatology ,Wavelength ,Control and Systems Engineering ,Pulsed mode ,Continuous wave ,Optoelectronics ,pulsed and continuous wave (cw) regimes ,business - Abstract
The paper deals with the medical application of diode-lasers. A short review of medical therapies is presented, taking into account the wavelength applied, continuous wave (cw) or pulsed regimes, and their therapeutic effects. Special attention was paid to the laryngological application of a pulsed diode laser with wavelength 810 nm, and dermatologic applications of a 975 nm laser working at cw and pulsed mode. The efficacy of the laser procedures and a comparison of the pulsed and cw regimes is presented and discussed.
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- 2021
38. Ultrasound-guided glossopharyngeal nerve block via the styloid process for glossopharyngeal neuralgia: a retrospective study
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Guanghong He, Qian Liu, Guoqiang Tang, and Qing Zhong
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medicine.medical_specialty ,business.industry ,Visual analogue scale ,medicine.medical_treatment ,Ultrasound ,Retrospective cohort study ,Microvascular decompression ,Ultrasound guided ,Glossopharyngeal neuralgia ,Surgery ,03 medical and health sciences ,0302 clinical medicine ,Anesthesiology and Pain Medicine ,030202 anesthesiology ,Medicine ,Pulsed mode ,business ,Glossopharyngeal nerve block ,030217 neurology & neurosurgery - Abstract
Objective To examine the effectiveness and safety of ultrasound-guided glossopharyngeal nerve block via the styloid process for primary glossopharyngeal neuralgia. Methods This retrospective study included all patients receiving glossopharyngeal nerve block via the styloid process under ultrasound guidance for primary glossopharyngeal neuralgia between January 2015 and May 2018 at our hospital. The primary outcome of the study was pain relief as assessed using the visual analog scale (VAS). Treatment was considered effective if the VAS score decreased by more than 2 points. Results Twelve patients were included in the analysis. The baseline VAS scores ranged from 5 to 9. All patients received previous pharmacotherapy. Other previous treatments included pulsed mode radiofrequency (n=4), microvascular decompression (n=2), and glossopharyngeal nerve block (not under ultrasound guidance; n=2). The patients completed a total of 48 injections for glossopharyngeal nerve block. At discharge from the hospital, and at 6, 12, and 18 months thereafter, 10/12, 10/12, 7/12, and 4/12 patients achieved pain relief and the effective rate was 83.3% at discharge, 83.3% at 6 months, 58.3% at 1 year, and 33.3% at 18 months, respectively. Conclusion Ultrasound-guided glossopharyngeal nerve block via the styloid process is a safe, radiation-free, repeatable, convenient, and effective treatment. It can provide a treatment option for patients with glossopharyngeal neuralgia.
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- 2019
39. Comparative Study of Pulsed Versus Continuous High‐Intensity Focused Ultrasound Ablation Using In Vitro and In Vivo Models
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Hongfei Han, Jianzhong Zou, Lu Jiang, Qi Wang, Yanhao Wang, Yong Luo, Jianli Chen, Lidan Gan, and Zihuan Zeng
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Necrosis ,medicine.medical_treatment ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,0302 clinical medicine ,In vivo ,Liver tissue ,medicine ,Animals ,Radiology, Nuclear Medicine and imaging ,030219 obstetrics & reproductive medicine ,Radiological and Ultrasound Technology ,business.industry ,Ablation ,In vitro ,High-intensity focused ultrasound ,Liver ,Models, Animal ,Microbubbles ,High-Intensity Focused Ultrasound Ablation ,Pulsed mode ,Cattle ,Rabbits ,medicine.symptom ,business ,Biomedical engineering - Abstract
OBJECTIVES To compare the efficacy of pulsed high-intensity focused ultrasound (PHIFU) versus continuous high-intensity focused ultrasound (CHIFU) ablation at identical doses. METHODS Continuous and pulsed HIFU (1200 J) at duty cycles (DCs) of 60% and 20% were examined for their capacity to ablate bovine liver tissue in vitro and rabbit liver tissue in vivo. After ablation, grayscale changes and pathologic characteristics were observed or measured, and the tissue necrosis volume, energy efficiency factor, and average grayscale density were calculated. RESULTS The pulsed mode generated greater liquefaction necrosis. An inconspicuous grayscale change was observed for PHIFU at a DC of 20% in some samples, which appeared as an elliptical cavity. The energy efficiency factor of PHIFU at a DC of 60% was significantly lower than that of CHIFU, as observed both in vitro and in vivo (P
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- 2019
40. The efficiency indicator for information visualization system of the Tokamak experimental device operating in repetitively pulsed mode
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V.M. Pavlov, A.A. Deriglazov, O. Kabrysheva, A. A. Mezentsev, and Yu. N. Golobokov
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Tokamak ,business.industry ,Computer science ,Mechanical Engineering ,Real-time computing ,Control (management) ,01 natural sciences ,Multi-objective optimization ,010305 fluids & plasmas ,law.invention ,Task (computing) ,Information visualization ,Nuclear Energy and Engineering ,law ,0103 physical sciences ,Multiple criteria ,Pulsed mode ,General Materials Science ,Relevance (information retrieval) ,010306 general physics ,business ,Civil and Structural Engineering - Abstract
The multi-objective method evaluating the performance of the information visualization system of tokamak-type experimental device is presented. The method takes into account special features of the tokamak operation. The indicator includes not only evaluation of the space-time distribution of information in the shared display space of the information visualization system, but also relevance of information. The task of multiple criteria decision making is performed using Pareto optimization. This method is used to design the information visualization system of control console for the KTM tokamak.
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- 2019
41. Plasma generation in the pulsed mode of the non-self-sustained arc discharge with combined heated and hollow cathods
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Yu.Kh. Akhmadeev, V. V. Denisov, V. V. Yakovlev, N. N. Pedin, N. N. Koval, and S. S. Kovalsky
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Electric arc ,Materials science ,business.industry ,Optoelectronics ,Pulsed mode ,Plasma ,Geotechnical Engineering and Engineering Geology ,business - Published
- 2019
42. Posterior laryngofissure using a surgical contact diode laser: an experimental feasibility study
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Paulo Manuel Pêgo-Fernandes, Christopher Kengo Nagao, Paulo Francisco Guerreiro Cardoso, Mauro Canzian, Benoit Jacques Bibas, José Pinhata Otoch, Arteiro Queiroz Menezes, Isaac de Faria Soares Rodrigues, Helio Minamoto, Marília Wellichan Mancini, and Marisa Dolhnikoff
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Larynx ,Swine ,Scalpel blade ,Dermatology ,law.invention ,030207 dermatology & venereal diseases ,03 medical and health sciences ,0302 clinical medicine ,law ,Electrocoagulation ,Animals ,Medicine ,business.industry ,Significant difference ,030206 dentistry ,Laser ,medicine.anatomical_structure ,Morphometric analysis ,Feasibility Studies ,Pulsed mode ,Surgery ,Thermal damage ,Laser Therapy ,Lasers, Semiconductor ,business ,Nuclear medicine - Abstract
To evaluate the feasibility of a 980-nm contact diode laser (CDL) as a method for creating a posterior laryngofissure in live pigs. Twenty-eight Landrace pigs (15–20 kg) were anesthetized, intubated, ventilated, and submitted to a cervical tracheostomy. An anterior and posterior midline longitudinal laryngofissure incision was created according to randomization—control (n = 4), posterior laryngofissure with a scalpel blade; electrocautery (n = 12), posterior laryngofissure by electrocautery (10, 15, 20, 25 W powers); CDL (n = 12), posterior laryngofissure by the CDL (10, 15, 20, 25 W peak powers in pulsed mode). Larynx and proximal trachea were excised, prepared for histopathology, and digital morphometric analysis. Measurements in and within each group were analyzed (Kruskal-Wallis and Dunn test) with a level of significance of p
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- 2019
43. Radiation safety study for the beam commissioning of IFMIF/EVEDA LIPAc RFQ in Rokkasho
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Juan Knaster, S. Ohira, Dominique Gex, Keishi Sakamoto, Masayoshi Sugimoto, Keitaro Kondo, Atsushi Kasugai, and Hervé Dzitko
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Mechanical Engineering ,Nuclear engineering ,Beam commissioning ,Radiation ,01 natural sciences ,010305 fluids & plasmas ,Nuclear Energy and Engineering ,Duty cycle ,0103 physical sciences ,Water pipe ,Environmental science ,Pulsed mode ,General Materials Science ,Neutron ,010306 general physics ,Dose rate ,Civil and Structural Engineering - Abstract
The construction of the Linear IFMIF Prototype Accelerator (LIPAc) is in progress at Rokkasho, Japan. The important milestone of the project is to commission the necessary components, namely RFQ, MEBT and diagnostics, to accelerate the proton beam up to 2.5 MeV or the deuteron beam up to 5.0 MeV in pulsed mode with a low duty cycle of 0.1%. The detailed radiation safety analysis has been conducted for the beam commissioning with the consideration of the specific radiation source conditions and the building configuration. As a result, it turned out that the dose rate expected outside the accelerator vault during deuteron beam operation at 5 MeV is mostly dominated by the neutron streaming effect through three major penetration sectors, i.e. HVAC ducts, water pipe holes and underground pits, while it is negligibly small during the proton beam operation at 2.5 MeV. It was confirmed that the dose rate expected does not exceed the legal limit for the controlled area boundary and no serious radiological issues exist in the beam commissioning planned.
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- 2018
44. Valorization of the use of Waste Agricultural Materials for the Anodic Oxidation of Amaranth Red (E123) using SS/PbO2 Anodes Elaborated by Pulsed Mode Current
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Amina Othmani
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chemistry.chemical_compound ,Materials science ,chemistry ,Anodic oxidation ,Metallurgy ,Pulsed mode ,Amaranth ,Current (fluid) ,Anode - Abstract
The present paper aims to valorize the use of cheap agricultural waste materials for polluted water decontamination. An evaluation of the efficiency of coupling anodic oxidation (AO) using SS/PbO 2 electrodes with biosorption by Luffa cylindrica (L.C) for the removal of Amaranth Red (E123) from aqueous solution was investigated. The effects of pH, contact time, and initial concentration were studied. The regeneration of L.C was estimated based on biosorption /desorption tests. The performance of the coupling process was evaluated based on the color, chemical organic carbon (COD), Total organic carbon (TOC) removals, the energy consumed, and the time required for the degradation of Amaranth. A comparison between the efficiency of the AO and the coupling process for the increase of the lifetimes of the anodes used was done. 54.1, 97.8, and 99.9% of 50 mg.L -1 of Amaranth were removed respectively after 85, 65, and 50 min by biosorption, AO, and coupling AO with biosorption. An increase in the percentages of COD, TOC, germination indexes (GI), and Amaranth removals were observed when adopting the coupling process. Furthermore, a decrease in the release of Pb 2+ ions was observed confirming the good stability of the elaborated anodes during the coupling process. Atomic absorption analysis showed that the Pb 2+ ions reached about 0.020 mg.L -1 , after the total removal of Amaranth dye (60 min) and 0.051 after (80 min) respectively, for coupling AO with biosorption and the AO process. These values are inferior to those allowed by the Standards. Phytotoxicity tests confirmed the possibility of the reuse of the treated solutions.
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- 2021
45. Photoionization of cobalt impurities in zinc oxide.
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Ivanov, Vitalii Yu., Godlewski, Marek, and Dejneka, Alexander
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PHOTODISSOCIATION , *FIELD ionization , *ZINC oxide , *PHOTOIONIZATION , *ELECTRON spin - Abstract
Electron Spin Resonance investigations allow to attribute a broad absorption band below the band-to-band transition of ZnO:Co to photoionization transitions of Co-ions. This absorption, with the onset at about 2.4-2.6 eV, is due to cobalt recharging, as concluded from the photo-ESR and pulsed ESR experiments. In these experiments light sensitive ESR signals of Co2+ and shallow donor are observed. Their response to light favors cobalt 2+ to 3+ photoionization. [ABSTRACT FROM AUTHOR]
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- 2015
- Full Text
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46. APPLICATION OF PULSE ATOMIZING JET IN ELECTRIC ARC METALLIZING.
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ROYANOV, V. A. and BOBIKOV, V. I.
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ELECTRIC welding ,DYNAMIC pressure ,ELECTRIC arc ,STATIC pressure ,MICROSTRUCTURE - Abstract
The paper presents the results of investigation of pulse atomizing air jet application in electric arc metallizing. To ensure the pulsed mode, the respective device was developed allowing control of outflowing of a jet with frequency within 0-130 Hz. Oscillograms of variation of dynamic pressure are given. Dependence of pulse atomizing air jet on frequency of closing the spray gun nozzle channel is shown. Coating microstructures are given. Influence of pulsation frequency on composition of coatings spray-deposited with PP-MM-2 wire is shown. 15 Ref., 6 Figures. [ABSTRACT FROM AUTHOR]
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- 2014
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47. Diode-End-Pumped Midinfrared Multiwavelength Er:Pr:GGG Laser.
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Zhenyu You, Yan Wang, Jinlong Xu, Zhaojie Zhu, Jianfu Li, and Chaoyang Tu
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We report a diode-end-pumped midinfrared multiwavelength Er:Pr:GGG laser, generating the output powers of 324 and 354 mW in CW and pulsed modes, respectively. The slope efficiencies of CW and pulsed modes are 15.18% and 16.06%, respectively. Compared with Er:GGG, the laser properties of Er:Pr:GGG are much better and the self-termination bottleneck is broken successfully. The transverse beam profile and spectra of Er:Pr:GGG laser are measured and the relationship between lasing wavelengths and operating temperature in the triwavelength emission state are also studied. The Er:Pr:GGG crystal is a potential midinfrared laser gain medium in medical and military application. [ABSTRACT FROM PUBLISHER]
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- 2014
- Full Text
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48. High power microsecond fiber laser at 1.5 μm
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Ihor Pavlov, M. Emre Yagci, Ersan Tunckol, Svitlana Pavlova, and S. Koray Eken
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Amplified spontaneous emission ,Materials science ,business.industry ,Pulse duration ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Power (physics) ,Pulse (physics) ,010309 optics ,Microsecond ,Optics ,Fiber laser ,0103 physical sciences ,Pulsed mode ,Laser beam quality ,0210 nano-technology ,business - Abstract
In this work, we demonstrate a single frequency, high power fiber-laser system, operating at 1550 nm, generating controllable rectangular-shape μs pulses. In order to control the amplified spontaneous emission content, and overcome the undesirable pulse steepening during the amplification, a new method with two seed sources operating at 1550 nm and 1560 nm are used in this system. The output power is about 35 W in CW mode, and the peak power is around 32 W in the pulsed mode. The repetition rate of the system is tunable between 50 Hz to 10 kHz, and the pulse duration is adjustable from 10 μs to 100 μs, with all on the fly electronically configurable design. The system demonstrates excellent long and short time stability, as well as spectral and spatial beam quality.
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- 2020
49. Continuous versus pulsed microwave ablation in the liver: any difference in intraoperative pain scores?
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Athanasios Tsochantzis, Nevio Tosoratti, Argyro Mazioti, George Velonakis, Dimitrios Filippiadis, Alexis Kelekis, and Nikolaos Kelekis
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Percutaneous ,business.industry ,medicine.medical_treatment ,Microwave ablation ,Significant difference ,Gastroenterology ,Continuous mode ,Ablation ,continuous ,liver ,pulsed ,Intraoperative Pain ,Intensity (physics) ,percutaneous ,Medicine ,Pulsed mode ,Original Article ,Nuclear medicine ,business - Abstract
Background This study prospectively compared intraoperative pain scores during percutaneous microwave ablation of the liver in patients randomized between continuous and pulsed energy delivery algorithms. Methods During a 12-month period, 20 patients who underwent microwave liver ablation were prospectively randomized between 2 different energy delivery modes: "continuous mode" (CM, n=10) and "pulsed mode" (PM, n=10). All ablation sessions were performed using the same microwave ablation platform under computed tomographic guidance and intravenous analgesia. Within 30 min post ablation, all patients completed a questionnaire assigning a numeric pain intensity score from 0 (no pain) to 10. Results Mean pain scores were 8.17±1.850 in the CM group and 4.50±1.567 in the PM group, with a statistically significant difference of 3.667±2.807 pain units (P=0.001). The mean procedure time was 53.5±20.90 min in the PM group vs. 58.5±17.44 min in the CM group (P=0.279). The mean size of the lesions was 2.81±0.95 cm in the PM group and 2.81±0.85 cm in the CM group (P=0.984). On a per-lesion basis, technical success was achieved in all evaluable tumors in both groups. No difference was noted in the local tumor control on the 6-month imaging evaluation. No complications were observed in the CM arm, while small perihepatic hemorrhagic fluid collections were reported in the PM group. Conclusions Both algorithms for microwave energy delivery have comparable treatment effects in terms of 6-month local tumor control for liver lesions
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- 2020
50. First synthesis of monodispersed microparticles of copper oxide films by pulsed spray pyrolysis (PSP): structural, optical, and morphological investigations
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A. Chetoui, M. Ghemid, A. Zouaoui, and M. R. Khelladi
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Copper oxide ,Materials science ,Atomic force microscopy ,Analytical chemistry ,General Chemistry ,Spray pyrolysis ,symbols.namesake ,chemistry.chemical_compound ,chemistry ,parasitic diseases ,symbols ,Pulsed mode ,General Materials Science ,Raman spectroscopy - Abstract
This work describes the first synthesis of monodispersed systems by capitalizing on the Leidenfrost effect. We report herein the synthesis of monodispersed particles of copper oxide films by spray pyrolysis technique in pulsed mode. The aim of this work is to investigate the effect of different pulse sequences on the particles’ size. One pulse sequence consists of three spray-on durations $$\tau_{{{\text{on}}}}^{{{\text{spray}}}}$$ separated by two spray-off $$\tau_{{{\text{off}}}}^{{{\text{spray}}}}$$ time intervals. In this work, we have varied the $$\tau_{{{\text{off}}}}^{{{\text{spray}}}}$$ duration from 15 to 45 s by a step of 10 s and the spray-on period is kept constant on 15 s. The effect of the spray-off duration on structural, optical and morphological properties of copper oxide material is reported. Indeed, the obtained films are characterized by XRD, spectrophotometer, Raman spectroscopy, AFM, and SEM. It was revealed that the spray-off duration has a great impact on the copper oxide particles’ size.
- Published
- 2020
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