scholarly journals Влияние времени нарастания напряжения на переходные процессы при токовой перегрузке в стабилизированных ВТСП-проводах второго поколения

2019 ◽  
Vol 45 (22) ◽  
pp. 7
Author(s):  
В.А. Мальгинов
Keyword(s):  
Input Voltage ◽  
Alternating Current ◽  
Resistive State ◽  
Current Limitation ◽  
Reverse Transition ◽  
Htsc Tape ◽  
First Time

The effect of spontaneous reverse transition of the stable HTSC tape from the normal to the resistive state with rapid input voltage and current overload at alternating current is detected. For the first time it is established that during the occurrence of this effect and at the thickness of the stabilizer above 13 µm, the main heat releases occur in the copper stabilizer and are effectively discharged into the refrigerant, which significantly reduces the heating of the HTSC layer. In this case, the resistance of the secondary resistive state decreases and the time of its existence increases. These data make it possible to use the detected effect to increase the time of current limitation and reliability of HTSC current limiters.

scholarly journals Dissolution of iron in sodium chloride solution during alternating current polarization

2021 ◽  
Vol 318 (3) ◽  
pp. 51-62
Author(s):  
A. Bayeshova ◽  
◽  
A. Bayeshov ◽  
A. Kadirbayeva ◽  
F. Zhumabay ◽  
...  
Keyword(s):  
Sodium Chloride ◽  
Iron Hydroxide ◽  
Alternating Current ◽  
Iron Electrode ◽  
Half Cycle ◽  
Iron Compounds ◽  
Titanium Electrode ◽  
Sodium Chloride Solutions ◽  
Multi Stage ◽  
First Time

Iron compounds are widely used in many industries and engineering, and even in medicine. The existing methods of obtaining iron compounds are multi-stage and complex. The purpose of this work is to obtain iron (II) hydroxide and oxide from metal waste under alternating current action using one and two half-cycles. For the first time, the electrochemical behavior of iron electrode was studied by electrolysis method during alternating current polarization of industrial frequency in sodium chloride solutions. The iron polarization was carried out in pair with titanium, while the current density on the iron electrode varied in the range of 200-1200 A/m2, and on the titanium is in the range of 20-100 kA/m2. It is established that in the anode half-cycle of alternating current, iron is oxidized to form divalent ions. At this moment, the titanium electrode is in the cathode half-cycle, hydrogen is released on it, hydroxyl ions are formed in the cathode space. In the solution, ions interact with iron (II) ions to produce iron hydroxide. At temperatures above 600C, iron (II) hydroxide is dehydrated with the production of iron (II) oxide. The electrolysis was carried out in two electrolyzers connected to each other in parallel with the immersion of pair of “titanium-iron” electrodes into each electrolyzer. The iron dissolution occurs simultaneously in two half-cycles of alternating current and this approach is proposed for the first time. The process productivity increases by more than 1.5 times.

Solving the Conundrum of Active Site Density of PGM-free ORR Catalysts in situ Fuel Cells Using Fourier Transform Alternating Current Voltammetry

2021 ◽  
Author(s):  
Rifael Snitkoff ◽  
Ariel Friedman ◽  
Yan Yurko ◽  
Piotr Zelenay ◽  
Alan Bond ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Active Site ◽  
Alternating Current ◽  
Reduction Reaction ◽  
Active Species ◽  
Site Density ◽  
Alternating Current Voltammetry ◽  
Commercial Applications ◽  
First Time

Abstract Advances in the development of Pt-group metal-free (PGM-free) catalysts for oxygen reduction reaction in fuel cells produced active catalysts that allow to reduce the performance gap to the incumbent Pt-based materials. However, the utilization of the state-of-the-art PGM-free catalysts in commercial applications is currently impeded by their relatively low durability. Methods designed to study catalyst degradation in operating fuel cells are critical for the understanding and ultimately solving the durability issues. This work is the first report on the use of Fourier-transformed alternating current voltammetry (FTacV) as an electrochemical method for accurately quantifying the electrochemical site density of PGM-free ORR catalysts, and following their degradation during the operation of polymer electrolyte fuel cells. Using this method we were capable of detecting changes in performance of electrochemically active species (electrocatalytic centers in this case), allowing us, for the first time, to calculate the electrochemical active site density (EASD) which is necessary for the elucidation of the degradation mechanisms of PGM-free ORR catalysts in situ fuel cells.

scholarly journals Observation of the shock-induced β-Sn to b.c.t.-Sn transition using time-resolved X-ray diffraction

2019 ◽  
Vol 26 (1) ◽  
pp. 96-101 ◽  
Author(s):  
R. Briggs ◽  
R. Torchio ◽  
A. Sollier ◽  
F. Occelli ◽  
L. Videau ◽  
...  
Keyword(s):  
Phase Transition ◽  
European Synchrotron Radiation Facility ◽  
Maximum Pressure ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Reverse Transition ◽  
First Time ◽  
Pressure Phase ◽  
Good Agreement

Time-resolved X-ray diffraction measurements have been carried out on dynamically compressed Sn up to a maximum pressure of ∼13 GPa at the European Synchrotron Radiation Facility. The phase transition from β-Sn to body-centered tetragonal (b.c.t.) Sn has been observed using synchrotron X-ray diffraction for the first time undergoing shock compression and release. Following maximum compression, the sample releases to lower pressures for several nanoseconds until the reverse transition occurs. The data are in good agreement with previous shock boundaries that indicate that the β-Sn phase is stable ∼2 GPa higher than the static boundary upon compression and the b.c.t.-Sn phase is stable ∼1 GPa lower upon release. The transition to the high-pressure phase reveals a loss of texture in the X-ray diffraction data from the `quasi' single-crystal β-Sn structure to a more powder-like Debye–Scherrer ring.

Simulation of Three Levels Single Phase Inverter Using Proteus Software

2015 ◽  
Vol 793 ◽  
pp. 315-319
Author(s):  
M. Zhafarina ◽  
M. Irwanto ◽  
A.H. Haziah ◽  
N. Gomesh ◽  
Y.M. Irwan ◽  
...  
Keyword(s):  
Direct Current ◽  
Output Voltage ◽  
Single Phase ◽  
Pulse Wave ◽  
Input Voltage ◽  
Alternating Current ◽  
Exact Simulation ◽  
Phase Inverter ◽  
Single Phase Inverter

Photovoltaic is use to supply electricity from sunlight. Inverter is used to convert the direct current (DC) from photovoltaic to alternating current (AC). This project is to design and develop a single phase inverter that able to invert the input voltage of DC to output voltage of AC using PROTEUS software. The inverter based on 8 bits for one cycle of a driver pulse wave. This simulation used before doing the hardware. This software can save a lot of time on this exact simulation of the prototype.

scholarly journals Charge pump system operation of DC-DC converter MAX1759 in the voltage boost mode

2017 ◽  
pp. 48-59
Author(s):  
V. K. Bityukov ◽  
A. V. Mironov ◽  
N. G. Mikhnevich ◽  
V. A. Petrov
Keyword(s):  
Integrated Circuit ◽  
Output Voltage ◽  
Charge Pump ◽  
Input Voltage ◽  
System Operation ◽  
Pump System ◽  
Load Current ◽  
First Time

The study tested output voltage pulsations and pulsations of voltage on a flying capacitor when MAX 1759 integrated circuit of DC-DC converter is pumped in a voltage boost mode with an output voltage of 3.6V and 5.2V at an input voltage of 3.2V and a load current in the range of 5...100 mA. The analysis of the results obtained shows that the hysteresis comparator is the basis for the charge pump control. The algorithm for operating the charge pump system is described for the first time in detail

Alternating Current Photoconductivity in a Negative Photoconductivity Region

1972 ◽  
Vol 50 (14) ◽  
pp. 1685-1687 ◽  
Author(s):  
R. W. Tokarsky ◽  
D. E. Brodie
Keyword(s):  
Frequency Response ◽  
Unique Feature ◽  
Impurity Scattering ◽  
Alternating Current ◽  
Impurity Level ◽  
Charged Impurity ◽  
Intensity Modulated ◽  
First Time ◽  
Charged Impurity Scattering ◽  
Modulated Light

A.C. photoconductance measurements on Cu-doped CdSe films are carried out for the first time in a negative photoconductive region, using intensity modulated light (intrinsic). A unique feature of the frequency response is an increase in photoconductance, with increasing frequency, for frequencies between 1.5 and 10 Hz. This anomaly in the photoconductance is explained by including the effect of a mobility dependence on impurity level occupancy (i.e. charged impurity scattering).

Transitions and oscillatory regimes in two-layer geostrophic hetons and tripoles

2016 ◽  
Vol 810 ◽  
pp. 535-553 ◽  
Author(s):  
Biana Shteinbuch-Fridman ◽  
Viacheslav Makarov ◽  
Ziv Kizner
Keyword(s):  
Hamiltonian Dynamics ◽  
Vortex Structures ◽  
Central Vortex ◽  
Transition Mechanism ◽  
Reverse Transition ◽  
Numerical Noise ◽  
Fluid Layers ◽  
Different Types ◽  
Centrally Symmetric ◽  
First Time

We investigate numerically the transitions and oscillatory regimes in two-layer quasigeostrophic hetons and tripoles composed of patches of uniform potential vorticity (PV). The contour-surgery algorithms are employed, in which either some symmetries are preserved, or asymmetric evolution of the vortex structures is allowed, induced by generally asymmetric numerical noise. The fluid layers are assumed equally thick. First, the evolution of hetons is considered. A heton, a steadily translating pair of vortices residing in different layers, is antisymmetric in the sense that the two PV patches are opposite in sign and symmetric in shape about the axis of translation. A feebly stable heton, when exposed to weak antisymmetric perturbations, responds by developing an oscillation, which culminates in a transition to a new, substantially robust oscillating heton. The results obtained reinforce our earlier findings regarding the modon-to-modon transition (Kizner et al., J. Fluid Mech., vol. 468, 2002, pp. 239–270; Kizner, Phys. Fluids, vol. 18 (5), 2006, 056601; Kizner, UTAM Symposium on Hamiltonian Dynamics, Vortex Structures, Turbulence (ed. Borisov et al.), IUTAM Bookseries, vol. 6, 2008, pp. 125–133. Springer) and clarify the transition mechanism. Asymmetric perturbations might cause a heton-to-tripole transition. Next we consider the transitions and oscillations in carousel tripoles exposed to weak, generally asymmetric perturbations. A carousel tripole is a steadily rotating centrally symmetric ensemble of three PV patches, with the central vortex being located in one layer and the two remaining, satellite vortices in the other layer. Depending on the tripoles’ size, hence also on the shape of the satellite vortices, three different types of transition are revealed, the transition to a ringed (shielded) monopole being one of them. Whereas the transition of a ringed monopole into a tripole is a known phenomenon, the reverse transition in baroclinic flows is detected for the first time.

scholarly journals Operation of an inverting DC-DC converter with charge pumping and LDO in the LM 27762 microcircuit

2019 ◽  
pp. 35-43
Author(s):  
V. K. Bityukov ◽  
V. A. Petrov ◽  
A. A. Sotnikova
Keyword(s):  
Output Voltage ◽  
Voltage Drop ◽  
Input Voltage ◽  
Constant Frequency ◽  
Charge Pumping ◽  
Pumping System ◽  
Low Load ◽  
Normalized Parameters ◽  
Pumping Mode ◽  
First Time

The paper focuses on the study of operation of an inverting DC-DC converter with charge pumping and LDO, which are the part of the combined bipolar secondary power supply LM 27762. The measurements covered two modes amply included in the range of normalized parameters with input voltages equal to 3.5 and 5.5 V, and output voltages 1.8 and 4.9 V, respectively, as well as the mode with an input voltage of 5.0 V and an output voltage 4.7 V, with a difference in the input and output voltage not exceeding the normalized limit of the voltage drop across LDO . Pulsations of voltages were measured at various load currents from 15 to 250 mA at the positive and negative poles of the flying capacitor, at the output of the charge pumping system and, in the latter case, also at the output of the microcircuit. Based on the results obtained, it was shown for the first time how at low load currents up to about 100 mA the charge pumping system operates in the burst mode, and at higher currents, it operates in the charge pumping mode with a constant frequency

scholarly journals Novel method for immunofluorescence staining of mammalian eggs using non-contact alternating-current electric-field mixing of microdroplets

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Hiromitsu Shirasawa ◽  
Jin Kumagai ◽  
Emiko Sato ◽  
Katsuya Kabashima ◽  
Yukiyo Kumazawa ◽  
...  
Keyword(s):  
Electric Field ◽  
Three Dimensional ◽  
Alternating Current ◽  
Immunofluorescence Staining ◽  
Ac Electric Field ◽  
Novel Method ◽  
A New Technique ◽  
Antigen Antibody ◽  
First Time ◽  
Mammalian Eggs

Abstract Recently, a new technique was developed for non-catalytically mixing microdroplets. In this method, an alternating-current (AC) electric field is used to promote the antigen–antibody reaction within the microdroplet. Previously, this technique has only been applied to histological examinations of flat structures, such as surgical specimens. In this study, we applied this technique for the first time to immunofluorescence staining of three-dimensional structures, specifically, mammalian eggs. We diluted an antibody against microtubules from 1:1,000 to 1:16,000 and compared the chromatic degree and extent of fading across dilutions. In addition, we varied the frequency of AC electric-field mixing from 5 Hz to 46 Hz and evaluated the effect on microtubule staining. Microtubules were more strongly stained after AC electric-field mixing for only 5 minutes, even when the concentration of primary antibody was 10 times lower than in conventional methods. AC electric-field mixing also alleviated microtubule fading. At all frequencies tested, AC electric-field mixing resulted in stronger microtubule staining than in controls. There was no clear difference in a microtubule staining between frequencies. These results suggest that the novel method could reduce antibody consumption and shorten immunofluorescence staining time.

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