Alternating Voltage Source Research Articles

2D electrical admittance lattice model of biological cellular system for modeling electroporation

In this work, a new modeling approach is presented to obtain a two-dimensional transport lattice of a biological cellular system for the calculation of the potential distribution throughout the system and investigation of the corresponding membrane electroporation. The presented model has been obtained by a modified bilayer model of the cell membrane. This modified membrane model allows for an effective inclusion of the shape of the cell membrane in the potential calculation. The results of the model have shown good agreement with the results of the well-known Schwan equation and COMSOL Multiphysics for the circular cell. The simulation results show that both membranes of a mitochondrion can be simultaneously electroporated by an alternating voltage source with frequencies between 1 MHz and 1 GHz.

The effect of magnetic field variations on the spectral properties of tornado plasma

At atmospheric pressure and at a frequency of 9.1 kHz, a constructed magnetically stabilized tornado gliding arc discharge (MSGAD) system was utilized in this study to generate a non-thermal plasma with an alternating voltage source from 2,4,6,8 to 10 kV. Argon gas was used to generate the arc plasma with an adjustable flow rate using a flow meter regulator to stabilize the gas flow rate to 2 L/min. A gliding plasma discharge is achieved by a magnetic field for the purpose of a planned investigation. The influence of the magnetically stabilized tornado gliding arc discharge parameters such as magnetic field and applied voltage on microscopic tornado plasma parameters was studied. The electron temperature1was measured using a Boltzmann plot and the electron1density was1determined by the Stark1broadening method. The electron temperature ranged from 0.818 eV to 1.495 eV, and the electron density varied from 1.37 × 1018 cm−3 to 2.49 × 10 18 cm−3 at a magnetic coil with 350 turns. Subsequently, the electron temperature increased to a range of 1.029 eV–1.794 eV, and the electron density reached a range of 1.53 × 1018 cm−3 to 2.89 × 1018 cm−3 at a magnetic coil with 500 turns. It can be observed that the plasma properties exhibit a rise as the number of turns of the coil and the applied voltage increase.

Influence of the initial winding displacement on the indicators of the electromechanical induction accelerator of cylindrical configuration

Purpose. The purpose of the article is to determine the influence of the initial displacement of the windings on the indicators of an electromechanical induction accelerator of a cylindrical configuration with pulsed excitation from a capacitive energy storage and with short-term excitation from an alternating voltage source. Methodology. To take into account the interrelated electrical, magnetic, mechanical and thermal processes, as well as a number of nonlinear dependencies, we use the lumped parameters of the windings, and the solutions of the equations describing these processes are presented in a recurrent form. The mathematical model of the accelerator takes into account the variable magnetic coupling between the windings during the excitation of the inductor winding. When calculating the parameters and characteristics of the accelerator, a cyclic algorithm is used. Results. At a frequency of an alternating voltage source of 50 Hz, the current amplitude in the armature winding is less than in the inductor winding. With an increase in the source frequency to 250 Hz, the phase shift between the winding currents decreases. The current in the inductor winding decreases, and in the armature winding it increases. The accelerating components of the force increase, and the braking ones decrease. With an increase in the source frequency to 500 Hz, the current density in the armature winding exceeds that in the inductor winding. In this case, the phase shift between the windings is further reduced. Originality. When a cylindrical accelerator is excited, the largest amplitude of the current density in the inductor winding occurs at the maximum initial displacement of the windings, but the amplitude of the current density in the armature winding is the smallest. The largest value of the current density in the armature winding occurs in the absence of an initial displacement. When excited from a capacitive energy storage, the electrodynamic force between the windings has an initial accelerating and subsequent braking components. As a result, the speed of the armature initially increases to a maximum value, but decreases towards the end of the electromagnetic process. When a cylindrical accelerator is excited from an alternating voltage source, a phase shift occurs between the currents in the windings, which leads to the appearance of alternating accelerating and decelerating components of electrodynamic forces. The accelerating components of the force prevail over the braking components, which ensures the movement of the armature. Practical value. At a frequency of an alternating voltage source of 50 Hz, the highest speed at the output of the accelerator vzf=0.5 m/s is realized at an initial displacement of the windings z0=6.2 mm, at a frequency of 250 Hz, the highest speed vzf=2.4 m/s is realized at z0=3.1 mm, and at a frequency of 500 Hz the highest speed vzf=2.29 m/s is realized at z0=2.3 mm.

INFLUENCE OF AN EXCITATION SOURCE ON THE POWER INDICATORS OF A LINEAR PULSE ELECTROMECHANICAL CONVERTER OF INDUCTION TYPE

The purpose of the article is to evaluate the efficiency of an induction-type linear pulse electromechanical converter (LPEC) when operating in shock-power mode and excitation from an alternating voltage source (AVS) in comparison with excitation from a capacitive energy storage (CES). A mathematical model of an induction-type LPEC has been developed both when excited by a unipolar pulse from a CES and from an AVS using lumped parameters of the windings, which takes into account the interrelated electromagnetic, mechanical and thermal processes. It has been found that when the LPEC is excited from the AVS with a voltage frequency of 50 Hz, the electrodynamic force takes on a periodic decaying character with a significant prevalence of positive components of forces over negative ones. The maximum value of the force is much less, and the value of its impulse is much greater than in the LPEC, excited from the CES. With an increase in the frequency of the AVS voltage from 50 to 150 Hz, the highest value of the current density of the inductor winding decreases, and in the armature winding it increases. The greatest values of force and impulse of force are realized at a voltage frequency of 150 Hz. With an increase in the AVS frequency, the relative indicator of the efficiency of the LPEC increases. References 15, figures 4.

Displacement currents—class room demonstration

Maxwell’s equations describe the basic laws of electromagnetism. Ampere's law was not in accordance with the equation of continuity. Maxwell modified this law by introducing displacement current density. This forms the foundation for generation of electromagnetic waves leading to wireless communication. According to this modified Ampere's law, varying the electric field induces a changing magnetic field. This can be observed in the case of oscillation of charges in a capacitor connected to an alternating voltage source. The concept of displacement current density continues to puzzle the students. A classroom experiment to demonstrate/measure the displacement current density is proposed. Use of a coil–magnet system to generate varying voltage instead of an oscillator makes the setup simpler and cheaper. Also, this method serves multiple objectives of providing clear understanding on the generation of alternating voltage and its visualisation, the behaviour of capacitors, and the extension of this experiment to the working of antennas.

EFFECT OF VARYING VOLTAGE ON ELECTRON DENSITY IN OXYGEN HOMOGENEOUS DIELECTRIC BARRIER DISCHARGE UNDER ATMOSPHERIC PRESSURE

The formation of uniform dielectric barrier discharges (DBDs) under atmospheric pressure is a remarkable achievement with the addition of electronegative gasses in closed reactors. This work is the part of dielectric barrier discharge achieved under atmospheric pressure. A uniform glow discharge is produced in capacitive discharge reactor. An alternating voltage source (0-2.5) kV having frequency of 50Hz is applied across the two parallel disc electrodes. A couple of dielectrics (glass) used as a discharge barriers one on each electrode. The oxygen gas injected into the reactor controlled by mass flow controller with flow rate 30ml/min. The current-voltage waveforms for oxygen discharge achieved, fulfilling the basic conditions of discharge homogeneity. The diagnostic techniques rely on electrical discharge method and power balance method to differentiate discharges and estimate the electron density for different values of applied voltages. A significant relation is found indicating the variation of electron density with applied voltage.

Electrodynamic tests of power transformers with reactive-power compensation

It is shown that electrodynamic tests of power transformers are accompanied by the predominant consumption of a reactive power that is many times higher than the active-power consumption. A scheme of electrodynamic tests with longitudinal compensation of the reactive power using a capacitor bank is proposed. It allows a considerable reduction of the power that is consumed from the power-supply system. The parameters of the capacitor bank and the preliminary-charging voltage levels were determined that provide various current regimes for conducting both adjusting and actual short-circuiting experiments. The possibility of performing electrodynamic tests of power transformers with nominal powers of up to 630 MV A under the conditions of factory test centers using a controlled alternating-voltage source with a regulation range of 1.5–7.5 kV and a power of 22 MW was substantiated. Short-circuiting tests have a negative effect on the power-supply system because they are able to initiate a voltage dip with a duration of up to 0.2 s and even a dynamic-stability loss. As a result, the quality and reliability of electric-power supply of other consumers of the power-supply system deteriorate. The above negative consequences can be avoided and the required testing short-circuit current simultaneously provided via reduction of the total power consumed from the powersuppl system. In this study, the problem of the electromagnetic compatibility of an electrodynamic-test bench and a power-supply system is solved by compensating the reactive power during short-circuiting experiments.

Development of power supply devices for limitations of short circuit on the ship's hull

The authors of the paper have analysed the reasons and consequences of single-phase ground faults (hull faults). For all varieties of devices limiting the current single-phase ground faults, the most effective devices were found to be the arc-suppression coils with different switching circuits. In this case the measurement of circuit capacitance takes on a great importance. A number of variants of capacitance measurement is presented in the paper. The authors have had a detailed look at a device, limiting the single-phase short-circuit current. This device was developed on the basis of the Far Eastern Federal University under the direction of Dr. G.E. Kuvshinov. The device is provided with power supply that converts alternating current (AC) to direct current (DC), and is realised due to the use of semiconductor devices - transistors and diodes - in a bridge circuit. The technical outcome of this power supply application consists in the reduction of size and weight parameters (compared to the closest analogues) in order to connect the controlled voltage rectifier to the alternating voltage source, including mass and size of the capacitor bank of the current limiting circuit, and enhancing the dynamic parameters of the stage of uncontrolled charge of the output capacitor of the controlled voltage rectifier.

Dynamical Coulomb blockade of tunnel junctions driven by alternating voltages

The theory of dynamical Coulomb blockade is extended to tunneling elements driven by a time-dependent voltage. It is shown that for standard set-ups where an external voltage is applied to a tunnel junction via an impedance, time-dependent driving entails an excitation of the modes of the electromagnetic environment by the applied voltage. Previous approaches for ac driven circuits need to be extended to account for the driven bath modes. A unitary transformation involving also the variables of the electromagnetic environment is introduced which allows to split-off the time-dependence from the Hamiltonian in the absence of tunneling. This greatly simplifies perturbation-theoretical calculations based on treating the tunneling Hamiltonian as a perturbation. In particular, the average current flowing in the leads of the tunnel junction is studied. Explicit results are given for the case of an applied voltage with a constant dc part and a sinusoidal ac part. The connection with standard dynamical Coulomb blockade theory for constant applied voltage is established. It is shown that an alternating voltage source reveals significant additional effects caused by the electromagnetic environment. The hallmark of dynamical Coulomb blockade in ac driven devices is a suppression of higher harmonics of the current by the electromagnetic environment. The theory presented basically applies to all tunneling devices driven by alternating voltages.

교류 전압원의 극성에 따라 구동하는 양방향 반도체 변압기의 설계

Abstract In this paper, we propose a transformer of alternating voltage source utilizing a semiconductor, operating in bidirectional fashion. Transformer is a device transferring energy by inductive coupling between its winding circuits. Conventional transformer is a device, composed of a primary coil and a secondary coil, transforming an alternating voltage. The system we propose is designed with a single circuit transforming the level of voltage signal in two ways; from the source to the load, and vice versa. For semiconductor switches, the NPN transistor is connected to the alternating voltage source terminal, and emitter terminal is connected to the inductor in the system as an energy storage element. The control signal is applied to the base terminal of the semiconductors. We have shown that the system we propose, by adopting only one circuit, drives an alternating voltage transformer that changes the amplitudes of voltage signal in reciprocal way. Key Words : Transformer, Electromotive force (EMF), Semiconductor switches, Gradient of current flow, Time ratio

BOSONIZATION AND ITS APPLICATION TO TRANSPORT IN QUANTUM WIRES

This paper reviews the method of bosonization for one-dimensional interacting fermions. Example of its application to mesoscopic systems is presented with an explicit calculation of the spin and charge currents in an interacting quantum wire subject to a uniform magnetic field and alternating voltage source. Special emphasis is given to the details of the calculation using bosonization and Keldysh techniques.

Analysis and Control of Induced Electromotive Force in Control Cable

Causes of induced electromotive force (emf) in other circuit are analyzed when a single loop in control cable is connected to an alternating voltage source in this paper. The size of induced emf and its influence factors are discussed. Based on theoretical analysis and test, the control measures of induced emf in control cable are put forward.

A MEMS-Stabilized AC Voltage Reference Source

Two electronic circuits are described in which the pull-in voltage of capacitive microelectromechanical system (MEMS) devices is applied as a reference for a stable alternating voltage source at frequencies between 5 kHz and 100 kHz. The first circuit is a simple harmonic oscillator. This low-cost circuit is capable of achieving a stability of better than 10 muV/V over one day. The second circuit shows a concept for a self-adjusting feedback technique. The circuit adjusts itself to operate the MEMS capacitor at its pull-in voltage

Is Maxwell’s displacement current a current?

A recent TPT article describes an experiment in which a toroidal coil is placed between the plates of a capacitor that is connected to an alternating voltage source. An alternating voltage signal is developed between the ends of the toroid. It is often claimed that such an experiment demonstrates the magnetic field produced by Maxwell’s displacement current. The purpose of this note is to examine that claim. The key question is: Does the displacement current act as a source of magnetic field in the same way as a current in a wire? Our answer — although it is not new — may surprise some readers.

Minimal compression of ultrathin sections with use of an oscillating diamond knife.

With the aim to minimize compression artefacts in ultrathin sections, coincident with the stroke direction, we have invented an oscillating diamond knife. Results and theoretical considerations explaining its function are discussed. During conventional ultrathin sectioning the resultant compression is in the order of 20-35% of section height. This holds true for sections of samples embedded into Lowicryl HM20 and of the polymer polystyrene, cut with a 45 degrees diamond knife and floated on water. The oscillating knife reduces this compression almost completely. It consists of a diamond knife on which a low voltage piezoelectric translator (piezo) is mounted, which oscillates when the piezo is driven by an alternating voltage source. No additional cutting artefacts were observed in the micrographs when they were compared with sections produced without oscillating the knife.

Newton–Raphson approach for the analysis of ferroresonant circuits

During switching operations in a power system there is a possibility that an unloaded transformer may be energised by a voltage source through an intervening capacitor. The capacitor could be a stray capacitance between an energised transmission line and the transformer terminals, a capacitance between the open contacts of a circuit breaker or a capacitive divider of a capacitive voltage transformer. The series connection of an alternating voltage source, a linear capacitor and a saturable inductor is generally known as a ferroresonant circuit. Determination of the steady-state periodic responses of a ferroresonant circuit is described. The responses were obtained using a time-domain Newton-Raphson procedure and also using a hybrid technique. A continuation procedure is described for determining the multiple solutions of the ferroresonant circuit and the bifurcating solution branches.

Turnstile device for heralded single photons: Coulomb blockade of electron and hole tunneling in quantum confined p-i-n heterojunctions.

We show that if a double-barrier mesoscopic p-i-n heterojunction is driven by an alternating voltage source, then Coulomb blockade and quantum confinement effects together can suppress the quantum fluctuations usually associated with electron and hole injection processes in semiconductors. It is therefore possible to generate heralded single-photon states without the need for a high-impedance current source. Since the frequency of the alternating voltage source determines the repetition rate of the single-photon states and the magnitude of the junction current, the present scheme promises high precision photon-flux and current standards.

An implantable pressure sensor for use in cardiology

A miniaturized capacitive pressure sensor has been developed for implantation in the human heart. Since no d.c. current (max 10 μA) can be tolerated inside the heart for safety reasons, an a.c. measuring circuit is mandatory for this purpose. The sensor measures 2 mm × 2 mm and is sealed to a glass substrate by anodic bonding. For the a.c. mode of operation, a capacitive voltage divider and impedance converter have been designed and processed in a standard 3 μm CMOS process. The divider consists of the sensor capacitor and a reference capacitor, and the circuit is powered by an alternating voltage source. The pressure signal modulates the current in the power line. This results in a two-wire approach, with a low output impedance, in total absence of any d.c. components.