Статті в журналах: "Currents and voltages asymmetry"

1

Marciniak, Lubomir, and Mateusz Piątek. "The influence of the network asymmetry on the settings and sensitivity of an earth fault protection using higher harmonics." E3S Web of Conferences 84 (2019): 02008. http://dx.doi.org/10.1051/e3sconf/20198402008.

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Detection of high resistance earth faults in medium voltage networks is an important problem due to ineffectiveness of traditional earth fault protections. Such short circuits can be detected by the criterion of a reactive power of higher harmonics for zero sequence current and voltage. The main problem is determination of the power setting value in the protection, which depends on the asymmetry of phase-to-earth capacitances and higher harmonics in supply voltages, which are generated by non-linear loads. The intensive tests of the asymmetry of the zero sequence currents and voltages for harmonics and their reactive power have been carried out in 15 kV compensated network as a function of all relevant parameters, i.e.: maximum capacitance deviation of the network and protected line, percentage content of harmonics in supply voltages, capacitive current of the network and the line. It has been shown that third harmonics of the zero sequence voltage and current are the best suited for practical use, since the asymmetry reactive power of these components is the smallest among the considered harmonics and the protection sensitivity will be the highest.

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2

Romanova, Victoria, and Sergey Khromov. "Effect of asymmetry of supply voltages on asynchronous motor operation modes." E3S Web of Conferences 58 (2018): 03013. http://dx.doi.org/10.1051/e3sconf/20185803013.

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Effect of asymmetry of supply voltages on asynchronous motor operation modes was investigated using the computer-aided simulation experiments, the software complex Matlab and the package program Simulink. Publication relevance is determined by the necessity for performance of comparative analysis of the level of effect of asymmetry of supply voltages on asynchronous motors of different series and power capacities. Six motors of three different power capacities (5.5, 55, 160 kW) and of two different series (4A, AI) were modeled for investigation. The value of asymmetry of supply voltages was changed from 0 to 5%. The motor shaft load was changed from 0 to 120% of the motor rated load. Comparison of dependencies of the phase currents on the voltage unbalance ratio by reverse sequence (K2U) of asynchronous motors with short-circuited rotor series 4A and AI was made. The analysis and discussion of obtained investigation results were performed, recommendations on operation of asynchronous motors series 4A and AI in conditions of asymmetry of supply voltages were given.

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3

Marius Bîrlea, Nicolae, and Sînziana Iulia Bîrlea. "The current-voltage relation of a pore and its asymptotic behavior in a Nernst-Planck model." Journal of Electrical Bioimpedance 3, no. 1 (July 23, 2019): 36–41. http://dx.doi.org/10.5617/jeb.296.

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Abstract A model for current-voltage nonlinearity and asymmetry is a good starting point for explaining the electrical behavior of nanopores in synthetic or biological membranes. Using a Nernst-Planck model, we found three behaviors for the calculated current density in a membrane's pore as a function of voltage: a quasi-ohmic, slow rising linear current at low voltages; a nonlinear current at intermediate voltages; and a non-ohmic, fast rising linear current at large voltages. The slope of the quasi-ohmic current depends mainly on the height of the energy barrier inside the pore, w, through an exponential term, ew. The magnitude of the non-ohmic linear current is controlled by the potential energy gradient at the pore entrance, w/r. The current-voltage relationship is asymmetric if the ion's potential energy inside the pore has an asymmetric triangular profile. The model has only two assumed parameters, the energy barrier height, w, and the relative size of the entrance region of the pore, r, which is a useful feature for fitting and interpreting experimental data.

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4

Гольдман, Е. И., С. А. Левашов та Г. В. Чучева. "Особенности характеристик устойчивых к полевым повреждениям структур кремний-сверхтонкий окисел-поликремний". Журнал технической физики 53, № 4 (2019): 481. http://dx.doi.org/10.21883/ftp.2019.04.47444.9011.

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AbstractResults of studying the features of the current–voltage ( I – V ) and capacitance–voltage characteristics of field-resistant silicon–ultrathin oxide–polysilicon structures are presented. It turns out that the total recharging of localized electron states and minority carriers concentrated near the substrate–insulator interface, which occurs with a variation in the field voltage, is an order of magnitude higher than that of samples susceptible to damage by the field stress effect. The tunneling I – V characteristic is significantly asymmetric; notably, the current flowing from the field electrode into the silicon substrate is several orders of magnitude lower when compared with the current flowing from silicon to polysilicon at identical external voltages dropping across the insulating layer. To explain this asymmetry, it is assumed that a potential barrier in the transition layer from polysilicon to oxide, which separates the semiconductor electrode and substrate, has a height of ~1 eV and therefore always hinders electrical transport; for reverse currents, this barrier stops limiting the conductivity as soon as the tunneling level becomes higher than it.

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5

Zhezhelenko, I. V., V. E. Kryvonosov, and S. V. Vasilenko. "Criteria for Detecting Turn-To-Turn Short Circuit in Stator Windings Using Vector Analysis of Electric Motor Phase Currents." ENERGETIKA. Proceedings of CIS higher education institutions and power engineering associations 64, no. 3 (June 4, 2021): 202–18. http://dx.doi.org/10.21122/1029-7448-2021-64-3-202-218.

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At industrial enterprises, seaports, ships, more than 80 % of all electrical engineering equipment is asynchronous motors. In a number of cases, asynchronous motors operate with a sharply variable load, in an aggressive environment; herewith they receive power from the network with deviations of the power quality indicators from the normative ones, which causes their high damageability. Turn circuits in the stator windings account for about 40 % of cases of damage to the insulation of the asynchronous motors windings. Untimely detection of the initial moment of the appearance of defects in the asynchronous motors or disruption of the operating modes of the supply network and current circuits result in emergency situations of the electrical complex, equipment downtime and damage. The article discusses the issues of diagnostics of non-full-phase modes of current circuits, mains voltages and turn circuits in the stator windings of the asynchronous motors that receiving power from the networks in conditions of voltage asymmetry. The analysis of the vector diagrams of currents, voltages and additional phase angles of the phase currents displacement arising from the asymmetry of the mains voltages and turn circuits in the stator windings has been fulfilled. The results obtained made it possible to formulate criteria for identifying the initial moment of the turn circuit and two-phase modes, both in the network and in current circuits, in stationary modes. A method for non-destructive testing of the asynchronous motors state as well as a device for its implementation has been developed. The method is based on comparing the vectors of the measured phase currents of the asynchronous motors with their calculated values. The article presents the results of modeling the change in the vectors of phase currents from the number of closed turns in the winding of the asynchronous motors. The power series of asynchronous motors was established, for which the sensitivity of detecting the initial moment of the turn-to-turn short circuit is maximum. Analytical results of the dependence of the sensitivity coefficient for turn-to-turn short circuit on the absolute increment of the modules of phase currents and the corresponding phase angles have been obtained.

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6

Palka, Ryszard, Konrad Woronowicz, and Jan Kotwas. "Current mode performance of a traction linear induction motor driven from the voltage converter." Transportation Systems and Technology 4, no. 3 suppl. 1 (November 19, 2018): 105–14. http://dx.doi.org/10.17816/transsyst201843s1105-114.

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Background: The paper deals with the modelling of a traction Linear Induction Motor (LIM) for public transportation. Typical problems arising from the electromagnetic finite element model development are described. The end effect causes asymmetry of phase impedances of the LIM. Because of that, if the LIM is supplied from the voltage inverter, which is usually the case, the phase currents become asymmetric. This causes performance calculation discrepancies in models that assume phase current symmetry. Aim: The aim of the paper is to develop a method for calculating the imbalanced three-phase LIM currents to precisely predict the LIM performance. Methods: Here, a method is developed to calculate the LIM phase current asymmetry by means of a self-developed electromagnetic finite element program – ELMAG, capable of adapting mesh generation based on Reynolds, Péclet and skin-depth numbers. Results: The calculated asymmetric currents are used in a real size traction LIM calculation in COMSOL, to derive the performance characteristics for comparison with the results achieved when supplying the LLIM with the symmetric three phase current. Conclusion: These results show that the natural asymmetry of the currents is an important factor that must be considered in appropriately calculating the LIM performance.

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7

Warzecha, Adam, and Witold Mazgaj. "Effects Generated by the Magnetic Core Anisotropy of an Induction Motor." Energies 13, no. 9 (May 1, 2020): 2189. http://dx.doi.org/10.3390/en13092189.

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A theoretical analysis enables effects generated by the magnetic core anisotropy of an induction motor to be determined qualitatively. Relationships formulated between currents and magnetic flux linkages that are associated with three-phase stator windings enable the qualitative determination of spectra of currents or voltages of a typical induction motor. These relationships account for nonlinear and anisotropic magnetization characteristics of the motor core, both during idle running and motor starting. Based on these relationships, components of the amplitude Fourier spectra of symmetrical components of currents or voltages, which are useful in the diagnostics of stator or rotor core anisotropy, were selected. Field calculations were performed for the core of a two-pole 5.5 kW motor supplied by three-phase sinusoidal currents. The components of the induced voltage Fourier spectra in both the idle running and short-circuit state were similar to analogous components predicted based on theoretical studies. The components occurring in the spectra, which were obtained based on field calculations, were distinguished in the measured spectra of the symmetrical components of the phase currents. These components were applied to estimate representative current signal levels in the diagnostics of motor core anisotropy. Relative values of these signals did not exceed 60 dB; however, they were significant for assessing the internal asymmetry level of the motor stator or rotor core. The results of laboratory measurements confirmed the results of the theoretical analysis.

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8

Artemenko, M. Yu, Y. V. Kutafin, V. M. Mykhalskyi, S. Y. Polishchuk, V. V. Chopyk, and I. A. Shapoval. "SHUNT ACTIVE FILTER CONTROL OF A THREE-PHASE THREE-WIRE NETWORK IN THE COORDINATE SYSTEM OF THE TWO WATTMETERS METHOD." Tekhnichna Elektrodynamika 2021, no. 5 (August 16, 2021): 11–20. http://dx.doi.org/10.15407/techned2021.05.011.

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A combined control system for a shunt active filter in the coordinate system of the two-wattmeters method has been proposed, which, depending on the conditions of use, implements one of the four active filtration strategies, optimal according to a certain quality indicator. The most promising is the proposed integral strategy for active filtration control with the reference vector of line voltages of direct sequence, which provides symmetric sinusoidal currents of the network and the minimum pulsation of power consumption for the almost identical energy-saving effect as the concept of S. Fryze. New formulas for calculating the energy-saving effect and pulsations of the instantaneous power in a three-phase system of power in the case of the formation of an active current in the transmission line in the conditions of asymmetry of loading voltage and linear asymmetric load have been developed. Simulation studies have confirmed the adequacy of the proposed strategies and calculations. References 15, figures 5, tables 2.

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9

AFANAS’YEV, Alexander A. "Equations of a magnetoelectric valve motor for loop closures of the stator winding." Elektrichestvo 11, no. 11 (2020): 47–52. http://dx.doi.org/10.24160/0013-5380-2020-11-47-52.

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The article considers the differential equations of a switched permanent magnet motor in which a short-circuit fault occurred in one or more turns in one of parallel stator winding branches. Owing to the occurred asymmetry of the phase quantities, symmetrical line-to-line voltages at the stator winding terminals are assumed. It is shown that turn-to-turn short-circuit faults give rise to non-sinusoidal and imbalanced phase currents and voltages at the nominal load torque on the shaft, and it should be noted that initially, a growth of the frequency and ratios of currents in the phases with an increase in the number of short-circuited turns are observed, after which the phase currents tend to decrease (with a continuing growth in the current through the short-circuited loop), and the rotor stalling occurs. The growth of motor rotation frequency and decrease of its overloading capacity take place due to a growth in the demagnetizing effect of armature reaction caused by the current through the short-circuited stator winding turns.

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10

Chernyshov, Maxim, Valery Dovgun, Sergei Temerbaev, and Zumeyra Shakurova. "Hybrid power quality conditioner for three-phase four-wire power systems." E3S Web of Conferences 178 (2020): 01009. http://dx.doi.org/10.1051/e3sconf/202017801009.

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The article considers a hybrid power quality conditioner (HQPC) for 3-phase 4-wire systems with a distributed modular structure. Some conditioner modules provide compensation for the component currents and voltages that form the negative and zero sequence systems. The open structure of the HQPC, consisting of independent modules, allows compensating for distortions of currents and voltages of the 3-phase network caused by the nonlinear nature and asymmetry of single-phase loads. The compensation characteristics of the proposed conditioner were researched using a model developed in the MatLab environment. The simulation showed that the proposed conditioner can ensure normalization of power quality in 3-phase 4-wire system at various modes of network operation.

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11

Naumov, Igor, Sergey Podyachikh, Dmitri Ivanov, Alexander Tretyakov, and Andrey Bastron. "Analysis of unbalanced load low-voltage electrical networks operating modes." E3S Web of Conferences 295 (2021): 02005. http://dx.doi.org/10.1051/e3sconf/202129502005.

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The article discusses distribution electrical networks 0.38 kV operating modes, feeding individual residential buildings. The electrical energy parameters measurement were certified RESURS-UF2M device carried out. The currents and voltages time diagrams based on the measurements made and using Matlab technologies were constructed. It is established that the level of phase currents unbalance is quite high and causes significant three-phase power supply system unbalance voltage accordingly. The power of quality indicators - calculations, characterizing voltage unbalance were made, which were based on the measurements and the computer program “Asymmetry” was used. As well as the additional power losses coefficient determining by the phase currents unbalance, were calculations. Time diagrams these indicators are constructed and their analysis were made. As a result, the power of quality is significantly reduced by unbalance power consumption in the studied electrical network were founded. At the same time, the additional power losses are significant increases. Specific recommendations for the normalization electrical network-operating mode are given.

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12

Veinović, Slavko, Žarko Janda, Đorđe Stojić, Jasna Dragosavac, Dušan Joksimović, Ilija Klasnić, and Milan Đorđević. "Load angle estimation of synchronous generator." Zbornik radova Elektrotehnicki institut Nikola Tesla 30, no. 30 (2020): 81–91. http://dx.doi.org/10.5937/zeint30-29158.

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In this paper a load angle estimation method of round rotor synchronous generator is presented, for load angle limiter in AVR systems design purpose. To get information of load angle, it is necessary to have values of the one terminal voltage, one phase current and q-axis reactance Xq. Mentioned values are acquired by synchronous sampling technique and processed by discrete Fourier transformation. The accuracy of presented method highly depends on quality of zero-crossing detection of the input voltage signal and on the calculation estimation of the fundamental frequency. This method is of reduced sensitivity to higher harmonics presence contence in voltages and current waveforms. Another advantage, when compared to other dq or ab based calculations estimations, is the necessity of use only two measurement channels. Drawback of described approach is lack of immunity to current asymmetry. However, a solution to overcome this problem is offered by introducing the additional measurements into the algorithm to extract the synchronous sampled direct components of all three phase currents.

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13

Vu, Q. S., Bui Vu Minh, Minh Tran, and N. V. Korovkin. "New proposed fractional-polynomial functions: new recommendation for overcome the imbalance in three-phase systems." International Journal of Power Electronics and Drive Systems (IJPEDS) 12, no. 4 (December 1, 2021): 2243. http://dx.doi.org/10.11591/ijpeds.v12.i4.pp2243-2250.

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Non-linear loads or load imbalances, etc., are the typical causes of asymmetric operation of three-phase systems. The appearance of inverse (positive) and homopolar (zero) symmetric components cause damage to the systems and electrical equipment and increase the power losses on the transmission lines. Reactive power compensation is one of the solutions that can overcome this asymmetry. The difficulty that exists in many different methods is the optimal calculation of the value of the compensator. In this paper, a new method to overcome these problems is proposed and investigagted. The proposed method is based on the fundamental electrical quantities (voltages and currents) on the controllable values of the static compensation devices and overcoming of the asymmetric operation regime in the three-phase systems.

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14

Dziendziel, Agnieszka, Henryk Kocot, and Paweł Kubek. "Construction and Modeling of Multi-Circuit Multi-Voltage HVAC Transmission Lines." Energies 14, no. 2 (January 14, 2021): 421. http://dx.doi.org/10.3390/en14020421.

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A transmission network’s main objective is to continuously supply electrical energy to consumers. This article presents an analysis of the use of multi-circuit, multi-voltage overhead lines as a compromise between ensuring the system’s safe operation by increasing the transmission network capacity and managing the constraints related to its expansion. The considerations presented in this work include the construction of such lines, their operation, and modeling aspects. As part of the study, the potential for improving the environmental conditions around the lines is discussed in terms of the necessary area for their construction and the peak electromagnetic field strength in their vicinity. We also present a mechanical analysis of stress and sag coordination in the individual circuits of these lines. Then, we detail the method for determining the electrical parameters of multi-voltage lines’ series impedances and capacitance. Specific attention is given to the possibility of zero-sequence voltage that occurs in the systems despite the symmetric supply and load of circuits—especially in the circuits with the lowest voltages—that result from the line’s geometric asymmetry. We evaluate the impact of the line’s geometric asymmetry on the power system’s correct operation by determining the asymmetry factors. Finally, the accuracy of using a simplified symmetric model for lines with various geometric asymmetries is analyzed by studying the error of the short-circuit currents.

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15

Pizarro, G., L. Csernoch, I. Uribe, M. Rodríguez, and E. Ríos. "The relationship between Q gamma and Ca release from the sarcoplasmic reticulum in skeletal muscle." Journal of General Physiology 97, no. 5 (May 1, 1991): 913–47. http://dx.doi.org/10.1085/jgp.97.5.913.

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Asymmetric membrane currents and fluxes of Ca2+ release were determined in skeletal muscle fibers voltage clamped in a Vaseline-gap chamber. The conditioning pulse protocol 1 for suppressing Ca2+ release and the "hump" component of charge movement current (I gamma), described in the first paper of this series, was applied at different test pulse voltages. The amplitude of the current suppressed during the ON transient reached a maximum at slightly suprathreshold test voltages (-50 to -40 mV) and decayed at higher voltages. The component of charge movement current suppressed by 20 microM tetracaine also went through a maximum at low pulse voltages. This anomalous voltage dependence is thus a property of I gamma, defined by either the conditioning protocol or the tetracaine effect. A negative (inward-going) phase was often observed in the asymmetric current during the ON of depolarizing pulses. This inward phase was shown to be an intramembranous charge movement based on (a) its presence in the records of total membrane current, (b) its voltage dependence, with a maximum at slightly suprathreshold voltages, (c) its association with a "hump" in the asymmetric current, (d) its inhibition by interventions that reduce the "hump", (e) equality of ON and OFF areas in the records of asymmetric current presenting this inward phase, and (f) its kinetic relationship with the time derivative of Ca release flux. The nonmonotonic voltage dependence of the amplitude of the hump and the possibility of an inward phase of intramembranous charge movement are used as the main criteria in the quantitative testing of a specific model. According to this model, released Ca2+ binds to negatively charged sites on the myoplasmic face of the voltage sensor and increases the local transmembrane potential, thus driving additional charge movement (the hump). This model successfully predicts the anomalous voltage dependence and all the kinetic properties of I gamma described in the previous papers. It also accounts for the inward phase in total asymmetric current and in the current suppressed by protocol 1. According to this model, I gamma accompanies activating transitions at the same set of voltage sensors as I beta. Therefore it should open additional release channels, which in turn should cause more I gamma, providing a positive feedback mechanism in the regulation of calcium release.

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16

Kholiddinov, I. Kh, G. F. Musinova, M. E. Yulchiev, Z. Z. Tuychiev, and M. M. Kholiddinova. "Modeling Of Calculation Of Voltage Unbalance Factor Using Simulink (Matlab)." American Journal of Engineering And Techonology 02, no. 10 (October 31, 2020): 33–37. http://dx.doi.org/10.37547/tajet/volume02issue10-07.

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This paper presents the problem of power quality in asymmetric modes in low-voltage electrical networks. The modeling of determination of power value, voltages and currents and, accordingly, their symmetric components, using the Simulink package in the MatLab program is shown.

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17

Gao, Wei Zhao, Qing Chao Zhang, Ming Zhong Zheng, and Heng Chao Zhang. "A Control of Homeostasis for Three-Phase Load in Power System." Applied Mechanics and Materials 521 (February 2014): 298–302. http://dx.doi.org/10.4028/www.scientific.net/amm.521.298.

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With the increasing asymmetry of the three-phase load, the problem of three-phase imbalance in power system is becoming more serious every day. Asymmetrical three-phase voltages and currents affect the safe and stable operation of the power system.The main direction for solving the problem of unbalanced three-phase power system is reactive power compensation. But in present paper, we demonstrate a new method. First, we load the single-phase load into the phase with smallest current and keep oscillation. Then, considering that system stability requires as small as possible imbalance, so we treat line current as criterion and adjust part load into system phases to reduce the neutral current to a value less action. Thus we can achieve homeostasis of three-phase load. We also have realized it by simulation.

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18

ABU-QAHOUQ, JABER A., HONG MAO, and ISSA BATARSEH. "NONISOLATED MULTIPHASE HALF-BRIDGE-BUCK TOPOLOGY WITH INHERENT CURRENT SHARING CAPABILITY AND SOFT-SWITCHING AND COUPLED-INDUCTORS CURRENT-DOUBLER." Journal of Circuits, Systems and Computers 13, no. 03 (June 2004): 443–66. http://dx.doi.org/10.1142/s0218126604001672.

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Point-of-load DC–DC converter requirements and design are increasingly becoming stricter than ever. This is due to the required tight dynamic tolerances allowed for supply voltages and high dynamic performance demand coupled with very high power density. Moreover, as the required converter output voltage becomes smaller, higher voltage step-down ratio is required, which results in smaller switching duty cycle in the nonisolated topologies. Step-down transformer with large turns ratio is used in the isolated topologies to step-down the voltage and keep larger duty cycle. Most of the nonisolated DC–DC topologies are buck-derived and unfortunately work at hard-switching which degrades the efficiency. DC–DC interleaved buck topologies were proposed but are highly sensitive to interleaved phases asymmetry and require high performance current sharing loop. In this paper, a nonisolated multiphase nonisolated half-bridge-buck topology is presented. This topology makes it possible to achieve soft-switching, works at larger switching duty cycle with lower output voltages, and does not require current sharing loop because of the inherent current sharing capability. Moreover, a coupled-inductor current doubler topology is also presented in this paper allowing higher step-down ratio and lower output current ripple. Theoretical analysis and experimental results are presented.

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19

Zhang, Chong, Daozhuo Jiang, Xuan Zhang, and Yiqiao Liang. "Research on an Asymmetric Fault Control Strategy for an AC/AC System Based on a Modular Multilevel Matrix Converter." Energies 12, no. 16 (August 15, 2019): 3137. http://dx.doi.org/10.3390/en12163137.

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This paper studies control strategies for an AC/AC system based on a modular multilevel matrix converter (M3C) when an asymmetric fault occurs in the secondary side ac system. Firstly, the operating principle of M3C is briefly introduced and verified by simulation. Then, based on its mathematical model by double αβ0 transformation, the decoupled control strategies for the primary side and secondary side systems are designed. In view of the asymmetric fault condition of the secondary side system, the positive sequence and negative sequence components of voltages and currents are separated and extracted, and then a proportional resonant controller (PR) is used to regulate the positive and negative sequence currents at the same time to realize decoupled current control in the αβ reference frames. The capacitor voltage balancing control, which consists of an inter-subconverter balancing control and an inner-subconverter balancing control, is realized by adjusting four circulating currents. Finally, the proposed control strategy is validated by simulation in the PSCAD/EMTDC software (Manitoba HVDC Research Center, Canada). The result shows that during the period of the BC-phase short-circuit fault occurring in the secondary side system, the whole system can still operate stably and transmit a certain amount of active power, according to their set values. Furthermore, the capacitor voltages are balanced, with a slight increase during the fault period. The simulation results verify the effectiveness of the proposed control strategy.

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20

Richardson, W. H. "Quantum Description of a Degenerate P-N Junction Coupled to an Electrical Circuit." International Journal of Modern Physics B 12, no. 24 (September 30, 1998): 2513–40. http://dx.doi.org/10.1142/s0217979298001472.

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A theory of Coulomb blockade of tunneling in a degenerate p-n junction is presented. Perturbation theory and temperature Green's functions are used to obtain the current–voltage characteristics. The formulation extends the theory of Coulomb blockade in MIM junctions, to junctions in which the characteristics of the device, is partly determined by the many particle interaction in the electrodes. Exact analytical expressions for the I-V at zero temperature and approximate expressions at nonzero temperatures are obtained. Among the novel features observed are: an asymmetry in the current–voltage characteristics even for voltages on the scale of the Coulomb blockade threshold and threshold like behavior below (e/2C).

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21

Константинян, К. И., Г. А. Овсянников, А. М. Петржик, А. В. Шадрин, Ю. В. Кислинский, G. Cristiani та G. Logvenov. "Резонансные ступени тока в джозефсоновских структурах с прослойкой из материала, обладающего сильным спин-орбитальным взаимодействием". Физика твердого тела 62, № 9 (2020): 1385. http://dx.doi.org/10.21883/ftt.2020.09.49758.03h.

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We report on results of experimental study of mesa heterostructures Nb/Au/Sr2IrO4/YBa2Cu3Ox with the barrier layer of Sr2IrO4, a material known as Mott antiferromagnetic insulator with high spin-orbit interaction energy, ESO ~ 0.4 eV. Under the influence of magnetic field H<15 Oe the resonant steps were registered at voltages Vn  1/L, inversely proportional to the width of the structures L. In contrast to the equidistant Fiske steps, changing the polarity of biasing current I, an asymmetry in Vn has been observed with a difference of voltage spacing between the steps. A change of applied magnetic field H has no effect of the voltages positions Vn , but the amplitudes of steps oscillate. Under microwave irradiation the Shapiro steps were observed demonstrating an oscillating behavior with power of applied microwaves.

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22

Shirokova, N., G. Pizarro, and E. Ríos. "A damped oscillation in the intramembranous charge movement and calcium release flux of frog skeletal muscle fibers." Journal of General Physiology 104, no. 3 (September 1, 1994): 449–76. http://dx.doi.org/10.1085/jgp.104.3.449.

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Asymmetric membrane currents and calcium transients were recorded simultaneously from cut segments of frog skeletal muscle fibers voltage clamped in a double Vaseline-gap chamber in the presence of high concentration of EGTA intracellularly. An inward phase of asymmetric currents following the hump component was observed in all fibers during the depolarization pulse to selected voltages (congruent to -45 mV). The average value of the peak inward current was 0.1 A/F (SEM = 0.01, n = 18), and the time at which it occurred was 34 ms (SEM = 1.8, n = 18). A second delayed outward phase of asymmetric current was observed after the inward phase, in those experiments in which hump component and inward phase were large. It peaked at more variable time (between 60 and 130 ms) with amplitude 0.02 A/F (SEM = 0.003, n = 11). The transmembrane voltage during a pulse, measured with a glass microelectrode, reached its steady value in less than 10 ms and showed no oscillations. The potential was steady at the time when the delayed component of asymmetric current occurred. ON and OFF charge transfers were equal for all pulse durations. The inward phase moved 1.4 nC/microF charge (SEM = 0.8, n = 6), or about one third of the final value of charge mobilized by these small pulses, and the second outward phase moved 0.7 nC/microF (SEM = 0.8, n = 6), bringing back about half of the charge moved during the inward phase. When repolarization intersected the peak of the inward phase, the OFF charge transfer was independent of the repolarization voltage in the range -60 to -90 mV. When both pre- and post-pulse voltages were changed between -120 mV and -60 mV, the equality of ON and OFF transfers of charge persisted, although they changed from 113 to 81% of their value at -90 mV. The three delayed phases in asymmetric current were also observed in experiments in which the extracellular solution contained Cd2+, La3+ and no Ca2+. Large increases in intracellular [Cl-] were imposed, and had no major effect on the delayed components of the asymmetric current. The Ca2+ transients measured optically and the calculated Ca2+ release fluxes had three phases whenever a visible outward phase followed the inward phase in the asymmetric current. Several interventions intended to interfere with Ca release, reduced or eliminated the three delayed phases of the asymmetric current.(ABSTRACT TRUNCATED AT 400 WORDS)

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23

Panchenko, Vladyslav, and Oleksandr Turenko. "ANALYSIS OF THE INFLUENCE OF VOLTAGE ASYMMETRY ON THE OPERATION OF THE TRACTION ASYNCHRONOUS ELECTRIC MOTOR USING THE SIMULATION MODEL." Collected scientific works of Ukrainian State University of Railway Transport, no. 198 (May 12, 2022): 145–50. http://dx.doi.org/10.18664/1994-7852.198.2021.256648.

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The asymmetry of the supply voltage adversely affects the operation of electricmotors, in particular induction ones. With an uneven load of the phases of the network, the voltagebecomes asymmetric - unequal between the individual phases. Voltage asymmetry leads to the factthat the currents in the phases of the stator winding of the electric motor differ sharply from oneanother. A phase with a high current can overheat above acceptable limits even with a small voltageunbalance. In addition, the active steel of the motor rotor overheats. Overheating of the motorwinding causes an increase in electrical losses, ripples of the electromagnetic torque also appear,and other negative consequences. These factors can lead to process failure, accelerated insulationaging, or even motor failure.In the event of a mains phase failure, running three-phase motors switch to single-phase mode.If the motor load before phase failure was no more than 60% of the rated value, then the motorcontinues to operate with slightly worse energy performance, the rotor speed decreases slightly, thewinding temperature is within acceptable limits. Under heavy loads, the motor winding overheatsexcessively, and in some cases the motor rotor stops and a large current flows through two phases ofthe stator winding. After stopping the engine, it cannot be started even at idle, since a pulsatingmagnetic field is obtained in the engine with a single-phase current.To study the effect of supply voltage asymmetry on the operation of an asynchronous electricmotor, simulation modeling was carried out in the ANSYS Electronics software package for directstart of induction motor with the introduction of a supply voltage asymmetry of one of the phases ata level of 4% in the steady state operation of the electric motor. The characteristics of the rotationfrequency and electromagnetic torque were obtained with asymmetry of the supply voltage and acomparison was made with the symmetrical mode of operation of the electric motor. The results ofsimulation show a slight change in the frequency of rotation of the rotor of the electric motor,however, there are significant ripples of the electromagnetic torque.

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24

Peter, A. B., J. C. Schittny, V. Niggli, H. Reuter, and E. Sigel. "The polarized distribution of poly(A+)-mRNA-induced functional ion channels in the Xenopus oocyte plasma membrane is prevented by anticytoskeletal drugs." Journal of Cell Biology 114, no. 3 (August 1, 1991): 455–64. http://dx.doi.org/10.1083/jcb.114.3.455.

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Foreign mRNA was expressed in Xenopus laevis oocytes. Newly expressed ion currents localized in defined plasma membrane areas were measured using the two-electrode voltage clamp technique in combination with a specially designed chamber, that exposed only part of the surface on the oocytes to channel agonists or inhibitors. Newly expressed currents were found to be unequally distributed in the surface membrane of the oocyte. This asymmetry was most pronounced during the early phase of expression, when channels could almost exclusively be detected in the animal hemisphere of the oocyte. 4 d after injection of the mRNA, or later, channels could be found at a threefold higher density at the animal than at the vegetal pole area. The pattern of distribution was observed to be similar with various ion channels expressed from crude tissue mRNA and from cRNAs coding for rat GABAA receptor channel subunits. Electron microscopical analysis revealed very similar microvilli patterns at both oocyte pole areas. Thus, the asymmetric current distribution is not due to asymmetric surface structure. Upon incubation during the expression period in either colchicine or cytochalasin D, the current density was found to be equal in both pole areas. The inactive control substance beta-lumicolchicine had no effect on the asymmetry of distribution. Colchicine was without effect on the amplitude of the expressed whole cell current. Our measurements reveal a pathway for plasma membrane protein expression endogenous to the Xenopus oocyte, that may contribute to the formation and maintenance of polarity of this highly organized cell.

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25

Kozlovskaya, V. B., and V. N. Kalechyts. "Asymmetrical Modes of Outdoor Lighting Lines." ENERGETIKA. Proceedings of CIS higher education institutions and power engineering associations 62, no. 3 (June 3, 2019): 232–46. http://dx.doi.org/10.21122/1029-7448-2019-62-3-232-246.

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Asymmetrical modes of the outdoor lighting network can be caused by disconnecting of a part of the luminaires in order to electrical energy savings at night; also – by asymmetry of voltage in power points. The possible alternative symmetric modes of energy saving to replace the incomplete-phase operation of the line have been analyzed. Calculations of various symmetric and asymmetric modes of the lighting line were carried out without taking into account and taking into account high harmonics up to the 39th one. Calculations have been performed with the programs of MathCad software. As light sources, in the calculations the widely used luminaries with high-pressure sodium arc lamps connected through electromagnetic start-up equipment were considered. Such luminaries are sources of high harmonics, and they distort the sinusoidal voltage. The values of currents, power, power loss, voltage drop in all areas of the lighting line, the voltage at the terminals of the lamps for each phase (operating parameters) are determined. The diagrams of the voltage distribution at the points of the lighting line are plotted for the considered modes of operation. The annual electric power consumption of the lighting line has been calculated for different variants of operation, and the obtained results have been compared. When refusing to disconnection of part of the luminaires at night and using a smooth transition to a lower voltage (symmetrical) at a power point or using two-stage ballast devices, uneven illumination appears less when the level of electricity consumption is comparable. The presence of voltage asymmetry at the power point, as well as the disconnection of one phase, leads to an increase in currents, power losses and voltage. The current in the zero working conductor can exceed the currents in the phase conductors (when calculated taking into account the higher harmonics). Accounting for higher harmonics allows one to determine the operating parameters more accurately, on the basis of which the electricity power consumption can be estimated.

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26

Grigoriev, Nikolai, Ivan Ignatenko, Vladimir Kovalev, and Polina Trofimovich. "Improvement of External and Traction Power Supply System’s Efficiency by Normalizing the Schemes." Известия высших учебных заведений. Электромеханика 64, no. 4-5 (2021): 72–78. http://dx.doi.org/10.17213/0136-3360-2021-4-5-72-78.

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The article deals with improvement off the efficiency of external and traction power supply systems using for example indicators of traction substations for a real electric transmission line segment of a traction network of 25 kV. The analysis of the functioning of a real section of electrified railways with traction substations, two of which are connected according to the "feeding" scheme is providing in the article. The currents in the wind-ings of traction transformers are calculate for these substations. The proportion of the currents values of the most loaded winding to the two less loaded is 2: 1. The coefficient asymmetry of currents of transformer wind-ings operating on existing traction substations is equal to 1. The results prove a significant currents asymmetry of transformers windings and phases of electric transmission lines which leads to an increasing voltage unbal-ance. New schemes for connecting traction substations for the considered section of electrified railways have been developed in order to improve the quality indicators of electrical energy. New connection schemes for three traction substations, determined according to the requirements for connecting to the external and trac-tion power supply system are presents in the article. The calculation for new schemes of connecting traction substations, similar to the previously considered option, has been performed. The values of winding currents, power transmission line phases and coefficient asymmetry were obtained for new substation connection schemes. The proposed schemes for connecting traction substations provide a decrease in the coefficient asym-metry of the winding currents from 1 to 0.5 and a decrease in the current modulus in the most loaded windings by 1.5 times. New schemes for connecting traction substations reduce the currents of the most loaded windings and phases of the power transmission line, as well as the asymmetry of currents, which ensures an improvement in the efficiency of the external and traction power supply systems of the real traction network.

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27

SOLJAN, Zbigniew. "Part 2: Reactive Compensation of the Linear Load in Three-Phase Four-Wire Systems Supplied with Asymmetrical Sinusoidal Voltage Following Currents’ Physical Components Theory." AUTOMATYKA, ELEKTRYKA, ZAKLOCENIA 11, no. 4(42)2020 (December 30, 2020): 52–64. http://dx.doi.org/10.17274/aez.2020.42.03.

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Four-wire systems are the most common ones in everyday life. Electrical installations within the home, office, or industrial plant are mostly four-wire installations. Receivers connected to such a system are mainly single-phase loads, which from the power connection are an unbalanced three-phase load. Apart from, the load imbalance, the supply voltage also has some asymmetry. Voltage asymmetry, load imbalance, the design of reactance compensators are issues that were not simultaneously included in the power equation in fourwire systems. This article presents the mathematical fundamentals of the construction of reactance compensators operating in voltage asymmetry.

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28

Kumar, R., and R. W. Joyner. "Calcium currents of ventricular cell pairs during action potential conduction." American Journal of Physiology-Heart and Circulatory Physiology 268, no. 6 (June 1, 1995): H2476—H2486. http://dx.doi.org/10.1152/ajpheart.1995.268.6.h2476.

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We have studied the L-type calcium current that occurs during action potential conduction between an isolated pair of guinea pig ventricular cells. To accomplish this, we first recorded action potentials from the leader cell (stimulated cell, cell 1) and the follower cell (nonstimulated cell, cell 2) with a fixed coupling resistance between the cells supplied by a coupling clamp circuit. We then applied these recorded action potentials as command potential waveforms for other cells studied in the voltage-clamp mode in which internal and external solutions that isolated the L-type calcium current were used. The action potential waveform of the leader cell had a rapid upstroke and then a partial repolarization during the conduction delay before activation of the follower cell. The L-type calcium current occurred with a large magnitude during the conduction delay for the leader cell but not for the follower cell. This leads to an asymmetry of calcium current for the two cells, with greater calcium current for the leader cell than for the follower cell. When we reversed the direction of conduction for cell 1 and cell 2 by stimulating cell 2, we found that application of these recorded waveforms for the action potentials for cell 1 and cell 2 to the voltage-clamped cells also reversed the asymmetry of the magnitude of the calcium current. We conclude that discontinuous conduction in cardiac tissue is associated with a directionally determined asymmetry in the magnitude of the calcium current, with the leader cell experiencing a greater peak calcium current than the follower cell.

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29

Saeed, Ismael Kareem, and Kamal Sheikhyounis. "Power quality improvement of distribution systems asymmetry caused by power disturbances based on particle swarm optimization-artificial neural network." Indonesian Journal of Electrical Engineering and Computer Science 25, no. 2 (February 1, 2022): 666. http://dx.doi.org/10.11591/ijeecs.v25.i2.pp666-679.

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With an increase of non-linear load in today’s electrical power systems, the rate of power quality drops and the voltage source and frequency deteriorate if not properly compensated with an appropriate device. Filters are most common techniques that employed to overcome this problem and improving power quality. In this paper an improved optimization technique of filter applies to the power system is based on a particle swarm optimization with using artificial neural network technique applied to the unified power flow quality conditioner (PSO-ANN UPQC). Design particle swarm optimization and artificial neural network together result in a very high performance of flexible AC transmission lines (FACTs) controller and it implements to the system to compensate all types of power quality disturbances. This technique is very powerful for minimization of total harmonic distortion of source voltages and currents as a limit permitted by IEEE-519. The work creates a power system model in MATLAB/Simulink program to investigate our proposed optimization technique for improving control circuit of filters. The work also has measured all power quality disturbances of the electrical arc furnace of steel factory and suggests this technique of filter to improve the power quality.

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30

Chernetskaya, I. E., and R. Yu Zakurdaev. "REVIEW OF EXISTING INSTRUMENTATION TO CORRECTION OF ASYMMETRY AND ANALYSIS OF ITS COMPLIANCE WITH THE MODERN AND PERSPECTIVE LEVEL OF INFORMATIZATION OF MUNICIPAL ELECTRIC NETWORKS." Proceedings of the Southwest State University 21, no. 5 (October 28, 2017): 16–26. http://dx.doi.org/10.21869/2223-1560-2017-21-5-16-26.

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The article deals with the problem of unbalance of currents and voltages of communal utilities and the degree of correspondence of existing solutions to the level of informatization. The classification and structure of measures to reduce asymmetry, existing means and devices for balancing are considered. Particular attention is paid to the switching method of asymmetry’s correction. The advantages of this method in comparison with the others are indicated in the article. It is established that at present the realization of this method is associated with considerable labor costs for personnel with minimal automation of the process. A comparative analysis of devices based on the switching method of balancing with other devices is performed. Several examples of devices are given. It was found out that devices, the principle of operation of which is based on the switching method, require significantly less investment than other devices. The analysis of the correspondence between the level of automation of the balancing process and the capabilities of automated systems for data collection and processing is carried out. Several devices of automated systems for monitoring and accounting of electric power and automated devices for monitoring the quality of electricity were considered. It was found out that automated systems for monitoring and accounting of electric power, in spite of lower accuracy of measurements, have an advantage over automated systems for monitoring the quality of electric power in their greater prevalence. It is concluded that with the existing level of equipping networks with such systems, information on asymmetry can be obtained with the necessary accuracy and without additional capital investments. The conclusion is made that the problem is topical and because of the analysis of existing methods for reducing asymmetry, the task is formulated of developing new methods, the realization of which is possible with the help of an automated advisory system.

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31

KAMOLOV, Mukhammadzhon М., Sagid A. АBDULKERIMOV, Khurshed B. NAZIROV, Shokhin D. DZHURAEV, and Saidjon Т. ISMOILOV. "Consideration of Nonsinusoidal/Unbalanced Operating Conditions of a Municipal Electric Network for Calculating the Current Level through the Neutral Conductor." Elektrichestvo 1, no. 1 (2021): 35–43. http://dx.doi.org/10.24160/0013-5380-2021-1-35-43.

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During the operation of 0.4 kV electric networks, asymmetry of currents and voltages is unavoidable. As is known, unbalanced operation of 0.4 kV networks is stemming from nonuniform distribution of loads between the phases. This results in that a fundamental frequency zero-sequence current will flow through the neutral conductor in a four-wire three-phase electric network. On the other hand, during balanced operation of a four-wire electric network containing loads with a nonlinear volt-ampere characteristic, higher harmonic currents multiple to three are summed in the neutral conductor. Therefore, it is of relevance to analyze unbalanced operating conditions of a four-wire electric network containing loads with a nonlinear volt-ampere characteristic. The article presents the characteristics of a municipal load for analyzing unbalanced/nonsinusoidal conditions of its operation. For carrying out full-valued assessment of unbalanced operating conditions of a four-wire electric network, a simulation model of a 0.4 kV network section containing a nonsinusoidal load is developed. It is shown that during unbalanced operation of an electric network containing electric loads with a nonlinear volt-ampere characteristic it is recommended to take into account zero-sequence current higher harmonic components that are not multiple to three. An algorithm for calculating the neutral conductor current harmonic component for determining the cable temperature rating is developed.

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32

Costa, Miraci S., Antônio T. M. Beirão, Carlos A. B. da Silva, Shirsley J. S. da Silva, and Jordan Del Nero. "Majorana Field Effect Transistor. Majorana Fermion Detection and Transport Properties." Journal of Computational and Theoretical Nanoscience 17, no. 11 (November 1, 2020): 4826–34. http://dx.doi.org/10.1166/jctn.2020.9406.

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In this work we obtain analytically the transport properties as current and conductance in a toy model system formed by a quantum dot with a single level connected to a Kitaev chain deposited on a s-wave superconductor to identify the signature of Majorana zero modes (MZMs) called Majorana Fermions in solid state. For this, we use the Non-Equilibrium Green’s Functions (NEGF) also named as Keldysh formalism in the matrix form to obtain the current–voltage (I–V) and conductance– voltage (G–V) curves to which goes to characterize the investigated system. Thus, it’s possible to verify the presence of the Majorana Fermions in three points: (i) Conductance peak in zero polarization; (ii) The current difference depends on the asymmetry of μL and μR. We find that only for μL = μR, the source and drain currents are equal. (iii) The current difference depends on the asymmetry of ΓL and ΓR.

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33

Omorov, T. T., B. K. Takyrbashev, and T. D. Koibagrov. "Electricy Losses Management in Distribution Network as a Composition of Automated Meter Reading and Control System (AMRCS)." Mekhatronika, Avtomatizatsiya, Upravlenie 22, no. 4 (April 5, 2021): 191–99. http://dx.doi.org/10.17587/mau.22.191-199.

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The problem of electricity losses management in distribution electric networks (DEN) operating in conditions of asymmetry of currents and voltages is reviewed. As it is known, the asymmetry factor leads to significant losses of active power and, as a result, decreases the efficiency and technical and economic indicators of the DEN. The purpose of the control is to minimize technical energy losses in the distribution network based on the creation of an automatic control system (ACS) for the process of balancing a three-phase network in the composition of automated meter reading and control system (AMRCS). The latter are currently being widely implemented to automate information processes in DEN. However, AMRCS does not include in its composition technologies designed to solve the problem under review. A method is proposed for constructing a digital ACS controller, the main function of which is to maintain phase currents at the network input at a given level in real time. The concept of the method is based on the idea of the desired redistribution of electricity flows between the phases of the distribution network by appropriate switching of single-phase consumers (customers) so that the minimum spread of phase currents from their specified level is ensured. To achieve the goal of control, criterion functions are constructed that determine the qualitative indicators of the functioning of the ACS. Algorithms for the functioning of the digital controller and the formation of control actions on the subject have been developed. The latter are a digital code containing data on the coordinates of electricity meters of consumers of a three-phase network to be switched to another phase.

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34

SOLJAN, Zbigniew. "Part 1: Decomposition of the Load’s Current in Three-phase Four-wire Systems Supplied with Asymmetrical Sinusoidal Voltage Following Currents’ Physical Components Theory." AUTOMATYKA, ELEKTRYKA, ZAKLOCENIA 11 (September 30, 2020): 34–42. http://dx.doi.org/10.17274/aez.2020.41.03.

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Electricity receivers in low-voltage networks are mainly single-phase loads, which, when grouped within a given consumer, create a three-phase load. Such a replacement three-phase load works in a four-wire system. Besides, under real conditions, the supply voltage has some amplitude and phase asymmetry. Voltage unbalances, load's imbalances are issues that not simultaneously included in the power equation in four-wire systems. This article eliminates the limitations of electrical engineering in this area by deriving the power equation for three-phase loads supplied with unbalanced voltage.

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35

Plaszkó, Noel L., Peter Rakyta, József Cserti, Andor Kormányos, and Colin J. Lambert. "Quantum Interference and Nonequilibrium Josephson Currents in Molecular Andreev Interferometers." Nanomaterials 10, no. 6 (May 28, 2020): 1033. http://dx.doi.org/10.3390/nano10061033.

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We study the quantum interference (QI) effects in three-terminal Andreev interferometers based on polyaromatic hydrocarbons (PAHs) under non-equilibrium conditions. The Andreev interferometer consists of a PAH coupled to two superconducting and one normal conducting terminals. We calculate the current measured in the normal lead as well as the current between the superconducting terminals under non-equilibrium conditions. We show that both the QI arising in the PAH cores and the bias voltage applied to a normal contact have a fundamental effect on the charge distribution associated with the Andreev Bound States (ABSs). QI can lead to a peculiar dependence of the normal current on the superconducting phase difference that was not observed in earlier studies of mesoscopic Andreev interferometers. We explain our results by an induced asymmetry in the spatial distribution of the electron- and hole-like quasiparticles. The non-equilibrium charge occupation induced in the central PAH core can result in a π transition in the current-phase relation of the supercurrent for large enough applied bias voltage on the normal lead. The asymmetry in the spatial distribution of the electron- and hole-like quasiparticles might be used to split Cooper pairs and hence to produce entangled electrons in four terminal setups.

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36

Jackman, C. M., and S. W. H. Cowley. "A model of the plasma flow and current in Saturn's polar ionosphere under conditions of strong Dungey cycle driving." Annales Geophysicae 24, no. 3 (May 19, 2006): 1029–55. http://dx.doi.org/10.5194/angeo-24-1029-2006.

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Abstract. We propose a simple model of the flow and currents in Saturn's polar ionosphere. This model is motivated by theoretical reasoning, and guided quantitatively by in situ field and flow data from space missions, ground-based IR Doppler measurements, and Hubble Space Telescope images. The flow pattern consists of components which represent (1) plasma sub-corotation in the middle magnetosphere region resulting from plasma pick-up and radial transport from internal sources; (2) the Vasyliunas-cycle of internal plasma mass-loss down the magnetospheric tail at higher latitudes; and (3) the polar Dungey-cycle flow driven by the solar wind interaction. Upstream measurements of the interplanetary magnetic field (IMF) indicate the occurrence of both extended low-field rarefaction intervals with essentially negligible Dungey-cycle flow, and few-day high-field compression regions in which the Dungey-cycle voltage peaks at a few hundred kV. Here we model the latter conditions when the Dungey-cycle is active, advancing on previous axi-symmetric models which may be more directly applicable to quiet conditions. For theoretical convenience the overall flow pattern is constructed by adding together two components - a purely rotational flow similar to previous axi-symmetric models, and a sun-aligned twin vortex representing the dawn-dusk asymmetry effects associated with the Vasyliunas-and Dungey-cycle flows. We calculate the horizontal ionospheric current associated with the flow and the field-aligned current from its divergence. These calculations show that a sheet of upward-directed field-aligned current flows at the boundary of open field lines which is strongly modulated in local-time by the Dungey-cycle flows. We then consider implications of the field-aligned current for magnetospheric electron acceleration and aurorae using two plasma source populations (hot outer magnetospheric electrons and cool dense magnetosheath electrons). Both sources display a strong dawn-dusk asymmetry in the accelerating voltages required and the energy fluxes produced, resulting from the corresponding asymmetry in the current. The auroral intensities for the outer magnetosphere source are typically ~50 kR at dawn and ~5 kR at dusk, in conformity with recent auroral observations under appropriate conditions. However, those for the magnetosheath source are much smaller. When the calculated precipitating electron energy flux values are integrated across the current layer and around the open closed field line boundary, this yields total UV output powers of ~10 GW for the hot outer magnetosphere source, which also agrees with observations.

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37

Khakimovich, Siddikov Ilkhomjon. "The Electromagnetic Transducers of Asymmetry of Three-phases Electrical Currents to Voltage." Universal Journal of Electrical and Electronic Engineering 3, no. 5 (September 2015): 146–48. http://dx.doi.org/10.13189/ujeee.2015.030502.

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38

Al-Shameri, Najla S., and Hassen Dakhlaoui. "Spin-Current Oscillations in Diluted Magnetic Semiconductor Multibarrier GaMnAs/GaAs: Role of Temperature and Bias Voltage." Coatings 12, no. 4 (April 8, 2022): 504. http://dx.doi.org/10.3390/coatings12040504.

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This paper has studied the electronic properties of multi-diluted magnetic semiconductor (DMS) layers Ga(1 − x)MnxAs interposed between nonmagnetic GaAs layers. The asymmetry of confining potential on the transmission coefficient by tuning the temperature and the size of the (DMS) layers was discussed. The diluted magnetic layers Ga(1 − x)MnxAs behave as barriers for spin-up holes and quantum wells for spin-down holes. Furthermore, we have addressed the impact of an applied bias voltage and the temperature on the variation of the spin-polarization and spin current densities. Our findings reveal that the transmission coefficients present an oscillating behavior due to the resonant states and strongly depend on the temperature of the system and the number of magnetic layers. Furthermore, the obtained results demonstrated that the number of these states is multiplied by augmenting the magnetic layers. Moreover, we demonstrate that the asymmetric structure presents a completely different transmission of holes than the symmetric structure. Furthermore, the negative differential resistance (NDR) is demonstrated in the current density variations. Especially, this (NDR) was more intense for spin-up holes than spin-down holes. The findings in the present paper can be useful in manufacturing spin-filters by adjusting the values of the temperature and the external voltages.

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39

Ridley, A. J., T. I. Gombosi, and D. L. DeZeeuw. "Ionospheric control of the magnetosphere: conductance." Annales Geophysicae 22, no. 2 (January 1, 2004): 567–84. http://dx.doi.org/10.5194/angeo-22-567-2004.

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Abstract. It is well known that the ionosphere plays a role in determining the global state of the magnetosphere. The ionosphere allows magnetospheric currents to close, thereby allowing magnetospheric convection to occur. The amount of current which can be carried through the ionosphere is mainly determined by the ionospheric conductivity. This paper starts to quantify the nonlinear relationship between the ionospheric conductivity and the global state of the magnetosphere. It is found that the steady-state magnetosphere acts neither as a current nor as a voltage generator; a uniform Hall conductance can influence the potential pattern at low latitudes, but not at high latitude; the EUV generated conductance forces the currents to close in the sunlight, while the potential is large on the nightside; the solar generated Hall conductances cause a large asymmetry between the dawn and dusk potential, which effects the pressure distribution in the magnetosphere; a uniform polar cap potential removes some of this asymmetry; the potential difference between solar minimum and maximum is ∼11%; and the auroral precipitation can be related to the local field-aligned current through an exponential function. Key words. Ionosphere (ionosphere-magnetosphere interactions; modelling and forecasting; polar ionosphere)

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40

Xiao, Muxuan, Feng Wang, Zhixing He, Honglin Ouyang, Renyifan Hao, and Qianming Xu. "Power Control and Fault Ride-Through Capability Analysis of Cascaded Star-Connected SVG under Asymmetrical Voltage Conditions." Energies 12, no. 12 (June 19, 2019): 2361. http://dx.doi.org/10.3390/en12122361.

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Анотація:

The cascaded H-bridge static var generator (SVG) has been employed to provide reactive power and regulate grid voltages for many years because of its good modularity, easy scalability, and improved harmonic performance. A novel cluster-balancing power control method combining negative-sequence currents and zero-sequence voltage is proposed to redistribute the unbalanced active powers and eliminate the power oscillation under asymmetrical conditions. Simultaneously, the dynamic performance of the SVG power balance control can be improved under asymmetrical conditions with the zero-sequence voltage expression derived in this paper. On the basis of the proposed method, the fault ride through capability of star-connected SVG under asymmetrical conditions is compared among active power oscillation elimination (APOE), reactive power oscillation elimination (RPOE), and balanced positive sequence current (BPSC) injection references calculation strategies from the perspective of the zero-sequence voltage, maximum phase voltage, and maximum phase current. The method provides the theoretical reference for power control under asymmetric conditions and the analysis results show that under asymmetrical conditions, the current of BPSC is minimal and symmetrical, while the RPOE has the least voltage and no zero- sequence voltage needs to be injected. Finally, the results of simulation and experiment have been given to verify the theoretical studies.

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41

SKRYPNYK, S., and A. SHEINA. "Short circuits currents comparison of 6 (10) kV and 20 kV." Journal of Electrical and power engineering 14, no. 1 (February 27, 2020): 21–26. http://dx.doi.org/10.31474/2074-2630-2020-1-21-26.

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Most failures in electrical installations are caused by short circuits (short circuits), which occur as a result of a failure in the electrical strength of the insulation of the conductive parts. A short circuit is an electrical connection of two points of an electric circuit with different values of potential, which is not provided by the design of the device, which interferes with its normal operation. Short circuits may result from a failure of the insulation of the current-carrying elements or the mechanical contact of the non- insulated elements. Also called a short circuit is a condition where the load resistance is less than the internal resistance of the power source. The reasons for such violations are various: aging of insulation, breakages of wires of overhead transmission lines, mechanical damages of isolation of cable lines at ground works, lightning strikes in the transmission line and others. Most often, short-circuits occur through transient resistance, such as through the resistance of an electric arc that occurs at the point of damage to the insulation. Sometimes there are metallic short circuits in which the resistance of the electric arc is very small. The study of short circuits in the power grid is a major step in the design of modern electrical networks. The research is conducted using computer software, first by modeling the system and then simulating errors. A malfunction usually leads to an increase in the current flowing in the lines, and failure to provide reliable protection can result in damage to the power unit. Thus, short-circuit calculations are the primary consideration when designing, upgrading, or expanding a power system. The three-phase short circuit is the least likely. However, in many cases, the three-phase short circuit is associated with the most severe consequences, as it causes the highest power imbalances on the shafts of the generators. The study of transients begins with the mode of three-phase closure due to its relative simplicity in comparison with other types of asymmetry. In most cases, the analysis and calculation of the transient regime of the electrical system involves the preparation of a calculated scheme of substitution, in which the parameters of its elements are determined in named or relative units. The electrical substitution circuitry is used to further study the transients in the power system. The definition of electrical and electromagnetic quantities in relative units is widely used in the theory of electric machines. This is because it significantly simplifies the theoretical calculations and gives the results a generalized view in the practical calculations of currents and residual voltages at the short circuit. By the relative value of any value is understood as its relation to another value of the same name, taken as the base. So, before presenting any quantities in relative units, we need to choose the basic units. In the electrical system with increased voltages, the overall load capacity of the network increases, which in turn makes it possible to supply high-quality electrical energy over a greater distance. In the process of comparing the type of transmission lines, it should be noted that the advantages of the cable transmission line. According to the results of the calculation of short-circuit currents, it can be concluded that in networks with a larger line cross-section and a higher voltage, the short-circuit currents are larger. Thus, during the transition of the electric networks to the higher voltage class of 20 kV, the currents of the KZ increased by 43% compared to the 6 kV electric network. This analysis shows that the importance of reliable power supply in the power supply system for high voltage classes must be high and have equipment to prevent emergencies. In the future, it is planned to develop a systematic calculation of short-circuit currents for a number of transmission lines and to conduct mathematical modeling in the system of applications for the study of transient processes at short circuits.

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42

Sobolev, Aleksandr Sergeevich, Alexei Viktorovich Vyngra, and Sergey Grigoryevich Cherniy. "Developing simulation model of active filter for marine intelligent transportation systems." Vestnik of Astrakhan State Technical University. Series: Marine engineering and technologies 2021, no. 2 (May 31, 2021): 90–98. http://dx.doi.org/10.24143/2073-1574-2021-2-90-98.

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The article studies the factors influencing the quality of electricity in the power supply systems of sea vessels. Problems caused by electromagnetic interference on ships including voltage drop in the electrical networks due to the nonlinear loads in the system, as well as power asymmetry are considered. The necessity of using active filters in autonomous power systems is found out. A model of an active filter for a closed power supply system with a nonlinear asymmetric load has been developed. The diagram of the active filter model in MATLAB / Simulink environment is illustrated. The simulation was carried out paying attention to various parameters of the system. There has been given an example of a program code for transforming the abc coordinates to the dq coordinates. The disadvantage of the considered circuit is stated: the greater the asymmetry and nonlinearity of the load, the lower the power for current filtering. There are considered the dependences between the measured value of voltage harmonic distortion (according to International Electronic Commission (IEC) 61000-2-4: 2002) and the observed phenomena in the unit; the measured value of the harmonic current distortion and the observed phenomena in the unit. According to the simulation results, it was inferred that the active current compensating filter will improve the quality of power on board the ship. The filter eliminates the imbalance, evens current harmonics and compensates the reactive component of currents. The scheme is advisable for using in autonomous systems of limited power on the merchant ships.

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43

Radovanović, J., V. Milanović, Z. Ikonić, and D. Indjin. "Design Considerations for Nonmagnetic Semiconductor-Based Spin Filters." Materials Science Forum 555 (September 2007): 41–46. http://dx.doi.org/10.4028/www.scientific.net/msf.555.41.

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In this paper we have analyzed the possibility of enhancing spin-polarization performance of conventional nonmagnetic semiconductor heterostructures which rely on the resonant tunneling mechanism. Both the bulk inversion asymmetry (BIA) and the structural inversion asymmetry (SIA) effects are taken into account in the presented model. The aim is to engineer nanostructures with maximal degree of spin separation in the electron tunneling current, which might be useful in studying various spin-related phenomena in semiconductor materials. Spin-polarization status of the current, in the devices under consideration, should be controllable by moderate emitter-collector voltages. Additionally, the spin orbit-interactions affect the dwell times of electrons in spin-up and spin-down states, therefore the prospects of spin-filtering in the time domain may be considered as well.

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44

Kandratsyeu, Aleh, Uladzimir Sabaleuski, Luis Redondo, and Andrei G. Pakhomov. "Four Channel 6.5 kV, 65 A, 100 ns–100 µs Generator with Advanced Control of Pulse and Burst Protocols for Biomedical and Biotechnological Applications." Applied Sciences 11, no. 24 (December 11, 2021): 11782. http://dx.doi.org/10.3390/app112411782.

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Pulsed electric fields in the sub-microsecond range are being increasingly used in biomedical and biotechnology applications, where the demand for high-voltage and high-frequency pulse generators with enhanced performance and pulse flexibility is pushing the limits of pulse power solid state technology. In the scope of this article, a new pulsed generator, which includes four independent MOSFET based Marx modulators, operating individually or combined, controlled from a computer user interface, is described. The generator is capable of applying different pulse shapes, from unipolar to bipolar pulses into biological loads, in symmetric and asymmetric modes, with voltages up to 6.5 kV and currents up to 65 A, in pulse widths from 100 ns to 100 µs, including short-circuit protection, current and voltage monitoring. This new scientific tool can open new research possibility due to the flexibility it provides in pulse generation, particularly in adjusting pulse width, polarity, and amplitude from pulse-to-pulse. It also permits operating in burst mode up to 5 MHz in four independent channels, for example in the application of synchronized asymmetric bipolar pulses, which is shown together with other characteristics of the generator.

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45

Kryukov, Andrey, and Evgeniy Bezridnyy. "MODELING TRACTION NETWORKS WHEN PASSING HEAVY TRAINS." Modern Technologies and Scientific and Technological Progress 2020, no. 1 (June 16, 2020): 207–8. http://dx.doi.org/10.36629/2686-9896-2020-1-207-208.

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The results of computer studies of the modes of traction power supply systems when passing trains weighing 12,000 tons are presented. The parameters are compared with the situation when trains are moving weighing 3,000 tons. It is shown that increasing the mass of trains with the same traffic volume leads to an increase in currents in the traction network, a decrease in voltage at the current collectors, the growth of asymmetry and harmonic distortion in the external power supply system

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46

Пустовая, О. А., Е. А. Пустовой, and Т. А. Илюхина. "INFLUENCE ON THE PERFORMANCE OF AUTOMATED SYSTEMS OF PHYSICAL PHENOMENA OCCURRING IN SINUSOIDAL CURRENT CIRCUITS." Vestnik APK Verhnevolzh`ia, no. 1(57) (March 30, 2022): 97–104. http://dx.doi.org/10.35694/yarcx.2022.57.1.015.

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Приводится обзор влияния качества электрической энергии и несимметричных режимов работы на системы автоматического управления технологическими линиями в сельском хозяйстве, с учётом приоритетных направлений развития российской промышленности и сельского хозяйства, а также с учётом перспективы цифровизации экономики страны. Рассмотрен вопрос влияния качества электроэнергии на термическое состояние электронных компонентов, работу асинхронных двигателей и другого оборудования. Показана возможность проведения диагностики электрического оборудования при помощи преобразования Парка. За время исследования среднее значение перекоса фаз по напряжению составило 3%, по току – 26,7%, для осветительного оборудования по напряжению – до 14%. Рассмотрено влияние перекоса фаз на работу цифровых систем управления высокого и низкого уровня автоматики и на компоненты электронных схем. Показано влияние перекоса токов и напряжений на деградацию электронных компонентов, в том числе SMD компонентов и микроконтроллеров. Показана возможность термического пробоя на примере твердотельного реле управления, которое было использовано совместно с асинхронным двигателем. Предложены методы устранения негативного влияния низкого качества электрической энергии и несимметрии токов и напряжений. Для устранения перекоса фаз высокотехнологичное оборудование рекомендуется подключать с использованием промышленных стабилизаторов напряжения, а также вести работу по модернизации электрических сетей 0,4 кВ. An overview of the influence of the quality of electric energy and asymmetric operating modes on automatic control systems of technological lines in agriculture is given, taking into account the priority areas of the development of Russian industry and agriculture, as well as taking into account the prospect of digitalization of the country's economy. The issue of influence of electric power quality on thermal state of electronic components, operation of asynchronous motors and other equipment is considered. The possibility of electrical equipment diagnostics by means of Park's transformation is shown. During the research the average value of phase imbalance in voltage was 3%, in current – 26.7%, for lighting equipment in voltage – up to 14%. Influence of phase imbalance on operation of digital control systems of high and low level of automation and on components of electronic circuits is considered. The influence of current and voltage distortion on the degradation of electronic components, including SMD components and microcontrollers, is shown. The possibility of thermal breakdown is shown on the example of a solid-state control relay, which was used together with an asynchronous motor. Methods of elimination of negative influence of low quality of electric energy and asymmetry of currents and voltages are proposed. To eliminate phase imbalance high-tech equipment is recommended to be connected using industrial voltage stabilizers, as well as to modernize 0.4 kV electrical networks.

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47

Naumov, I. V., N. V. Savina, and M. V. Shevchenko. "Modeling of three-phase electric motor operation by the MATLAB system with deteriorated power quality in the 0.38 kV distribution networks." E3S Web of Conferences 58 (2018): 03016. http://dx.doi.org/10.1051/e3sconf/20185803016.

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One of the main operation modes that characterizes power quality in distribution networks is asymmetry of three-phase voltage system. Operation of an induction motor (IM) with disturbed voltage symmetry in the supply network can not be considered as a rated one. The system of voltages applied to the stator winding of IM under these conditions contains positive- and negative-sequence components. This worsens the performance characteristics of IM essentially. In order to balance the 0.38 kV network operation and enhance the efficiency of the three-phase electric motor operation it is suggested to use a special balancing unit (BU) that minimizes the negative-sequence components of current and voltage. The operation modes of the obtained system “supply source – induction motor – balancing unit” are simulated within the MATLAB software package of applied programs, which allows one to assess the impact of low quality of power on the operating characteristics of the electric motor and the efficiency of the balancing unit to increase the “durability” of the motor under the asymmetrical power consumption.

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48

Dwyer, T. M. "Guanidine block of single channel currents activated by acetylcholine." Journal of General Physiology 88, no. 5 (November 1, 1986): 635–50. http://dx.doi.org/10.1085/jgp.88.5.635.

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The acetylcholine-activated channel of chick myotube was studied using the patch-clamp method. Single channel current amplitudes were measured between -300 and +250 mV in solutions containing the permeant ions Cs+ and guanidine (G+). G+ has a relative permeability, PG/PCs, of 1.6, but carries no more than half the current that Cs+ does, with an equivalent electrochemical driving force. Experiments using G+ revealed an asymmetry of the acetylcholine-activated channel, with G+ being more effective at reducing Cs+ currents when added to the outside than when added to the inside. The block caused by outside, but not inside, G+ was evident for both inward and outward currents. The block caused by outside G+ was voltage dependent, first increasing and then being partially relieved when the driving force was made more negative. Experiments with mixtures of Cs+ and G+ revealed anomalously low magnitudes for reversal potentials, relative to predictions based on the Goldman-Hodgkin-Katz equation. These findings are consistent with a two-well, three-barrier Eyring rate model for ion flow, and demonstrate that a highly permeant ion, guanidine, can block asymmetrically by acting from within the voltage field of the acetylcholine-activated channel.

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49

Masruroh, A., and Masayuki Toda. "Studies of Asymmetric Hysteresis Loops and Leakage Current Behaviors in Pt/Al₂O₃/SiO₂/Si /PZT/Au Structures Prepared by MOCVD Method." Applied Mechanics and Materials 110-116 (October 2011): 294–98. http://dx.doi.org/10.4028/www.scientific.net/amm.110-116.294.

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The polarization-voltage (P-V) and leakage currents density (J-V) characteristics were investigated on the ferroelectric PZT films deposited on Pt/Al2O3/SiO2/Si substrate with a vapor-deposited gold top electrode. The P-V hysteresis loops and the J-V characteristics were measured after performing a rapid thermal annealing (RTA) process. A ferroelectric test system (Precision LC Radiant Technology) was used to measure their electrical properties with a 90-nm PZT thickness and an area of 7.85 x10-5 cm2. The measurements were taken by connecting a Pt bottom electrode to the drive of the precision LC and the Au top electrode to the drive of the precision LC. The P-V hysteresis and J-V characteristics of PZT samples showed the asymmetry for both measurements. The asymmetric hysteresis loops and leakage current behavior were shifted in the positive direction when the drive was applied to the Pt electrode, while being negatively shifted in the converse case. The asymmetric behavior of the polarized state in the hysteresis loops due to the electrode configuration resulted from different work function between the Pt and Au electrodes, further influencing the leakage current behavior.

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50

Gontar, Yu, and T. Antonets. "Influence of heating dynamics of polymer insulation of medium voltage power cables on their performance." Lighting engineering and power engineering 3, no. 59 (November 27, 2020): 127–30. http://dx.doi.org/10.33042/2079-424x-2020-3-59-127-130.

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Currently, global trends in the development of medium voltage cable networks are aimed at the introduction of cables with cross-linked polyethylene insulation. Such cables are innovative products of domestic cable manufacturers. Most often, single-core cables are laid in parallel in one plane. The article analyzes a number of significant features of cables with cross-linked polyethylene insulation, which affect the thermal regime both in working condition and in emergency operation, among which - the dependence of thermal conductivity and heat capacity of polymer insulation on temperature. Cable throughput, which is determined by regulatory models and average environmental parameters, provides only preliminary information about its heating, useful for comparing its throughput with other cables of the same type. For certain requirements and for innovative cable designs, it is necessary to determine the capacity according to thermal constraints in specific operating conditions. Thermal and electrical asymmetry must also be taken into account in the test conditions of cables intended for laying three single-core cables in the plane. The heating of medium voltage cables with crosslinked polyethylene insulation was studied [1], an experimental assessment of the influence of the distance between the cables on the asymmetry of currents and temperatures was performed using three single-phase single-core cables АПвЭгаПу 1х70/16–35with the same current direction. It is established that in the absence of longitudinal currents in electrically conductive screens, the current in the middle core can be practically taken as a basis. It is proposed to use the method of concentrated heat capacities for the analysis of cable heating by overload current, which allows to significantly reduce the test time in production conditions. The study aims to create a method for determining the allowable current of medium voltage cables in specific operating conditions.

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