Interaction Of Magnetic Field Research Articles

Mitigation of Insulator Lightning-Induced Voltages by Installing Parallel Low-Voltage Surge Arresters

In this paper, we propose a mitigation method for reducing lightning-induced insulator voltages based on the installation of low-voltage surge arresters aligned parallelly to the insulator. The three-dimensional finite-difference time-domain (FDTD) method is applied to numerically model a real surge arrester residual voltage evaluation system. The application of a transient current pulse, typical of lightning discharges, is considered in our numerical model. We considered cases with one or two surge arresters installed per phase, in three different geometric and parametric configurations for installing distribution surge arresters. In addition to the Kirchhoff current division, which reduces both the absorbed energy and the thermal stress, the results associated with the installation of two surge arresters parallelly aligned to the insulator show that the interaction of magnetic fields generated by the surge arresters’ currents can produce an additional strong reduction in lightning-induced voltage over the insulator, as presented in this paper. Conditions for maximum voltage reduction are also identified. A brief cost-effectiveness analysis is also provided.

Spin-induced multipartite steady-state entanglement of motional modes in hexagonal boron nitride membranes

In this paper, we focus on a scheme in which three high-quality-factor mechanical modes of a hexagonal boron nitride (hBN) membrane monolayer are coupled to a common optically addressable spin defect present in the membrane via magnetic field interaction. We show that this coupling induces an effective phonon-phonon interaction in the dispersive regime and under appropriate magnetic field and microwave modulation. We derive the Langevin-Heisenberg equations of motion for vibrational modes to analyze optimal parameter regimes for reaching a physically stable system. We also investigate the effect of coupling strength on purity and entanglement. Our results demonstrate that bipartite and genuinely tripartite steady-state entanglement between different vibrational modes of hBN may be achieved in a broad spectrum of experimental parameters. This study has the potential to enable scalability to be implemented for the generation of two-dimensional continuous-variable cluster states for universal quantum computation.

Magnetic field and nuclear spin influence on the DNA synthesis rate

The rate of a chemical reaction can be sensitive to the isotope composition of the reactants, which provides also for the sensitivity of such “spin-sensitive” reactions to the external magnetic field. Here we demonstrate the effect of the external magnetic field on the enzymatic DNA synthesis together with the effect of the spin-bearing magnesium ions (^{25}Mg). The rate of DNA synthesis monotonously decreased with the external magnetic field induction increasing in presence of zero-spin magnesium ions (^{24}Mg). On the contrary, in the presence of the spin-bearing magnesium ions, the dependence of the reaction rate on the magnetic field induction was non-monotonous and possess a distinct minimum at 80–100 mT. To describe the observed effect, we suggested a chemical scheme and biophysical mechanism considering a competition between Zeeman and Fermi interactions in the external magnetic field.

Magnetic field-induced asymmetric mechanical metamaterials

We propose a magnetic field-induced asymmetric mechanical metamaterial. The tunable metamaterial integrates hard-Magnetic Active Elastomers (hMAEs) into the microstructural design combining snap-through, bi-stability, and local resonant effects. The proposed metamaterial design comprises resonating units made out of hMAE, and these units are supported by highly deformable curved beams connected with an elastomeric matrix. Activated by a magnetic field, the resonating units attain an unstable regime with dramatic configuration and stiffness variation. These controlled transformations significantly affect the elastic wave propagation. We illustrate that the proposed magnetoactive metamaterial enables bandgap tunability over a broadband low-frequency range. Thus, the proposed design allows remote and reversible control of the metamaterial performance. Moreover, the hMAE-based systems can incorporate the polarity and chirality stemming from the interaction of external magnetic fields and hMAE phases, giving rise to the unusual behavior of the metamaterial, and potentially enabling elastic cloaking.

Directional solidification of A356 aluminium alloy under the interaction of DC magnetic field and electric current

This article describes an experimental investigation and results of electromagnetic (EM) interaction during the continuous casting of the silicon-rich aluminum alloy A356. Directional solidification of aluminum rods with a diameter of 10 to 12 mm under the interaction of a moderate static magnetic field of 0.45 T and an applied DC electric current has been studied. The developed EM interaction drives a small-scale molten metal flow directly in the mushy zone, which impacts the heat and solute transport. However, this affects the microstructure and, in the end, the properties of the alloy. Tables 3, Figs 23, Refs 23.

Directional Solidification of Aluminum A360 under Moderate DC Magnetic Field and Electric Current

Metal additive manufacturing is rapidly developing technology, but its application in wider scale is limited by several factors. One of these is expensive raw material, because it requires certain physical properties. Two most popular metal additive manufacturing methods are printing from powder and printing from wire. Wire is usually produced by drawing it from rod. Rod can be produced by directional solidification, which is well known method to study the microstructure formation depending on various parameters during solidification. In this study directional solidification of A360 aluminum alloy with electromagnetic interaction is investigated. Aluminum alloy is induction melted and then directionally solidified into the rod 12-20 mm in diameter. Aim of this work is to investigate the role of axial DC magnetic field and electric current interaction on the grain refinement and mechanical properties of A360 aluminum alloy. It is found that electromagnetic interaction can be the approach to refine the grains, regulate the growth of oriented columnar grains and to improve mechanical properties of the material.

Stress-strain magnetoactive propulsion system

It is possible to create deformations in magnetically active polymeric materials by applying magnetic fields to them. This work develops a symmetrical design scheme of the device, in which the drive and control are carried out by two actuators located on opposite sides. The symmetric scheme with control from two sides allows transporting objects (cargo) in mutually opposite directions (forward and backward). It is proposed to use a magnetically active gel together with a magnetically active elastomer as magnetically active materials. The resulting force effect in the device actuator is produced by interaction of magnetic fields of electromagnets with magnetic fields of permanent magnets. Expressions for obtaining alternating magnetic fields which create conditions for generating alternating magnetic forces in the actuator of the device are given. A prototype design with a controller control device in which signals are generated for an optimum current pulse generator with adjustable duty cycle and duration is presented.

Magnetic field modulated dynamics of partial discharges in defects of high voltage insulating materials

This paper presents original measurement methodology and detection approach to determine the influence of the magnetic field on the partial discharge (PD) dynamics. The application areas refer to insulation systems of both grid and industrial network devices and emerging segments such as high-speed rail, electric vehicles or more electric aircrafts. Conventionally PD measurements are executed only in electric field, however the interaction of magnetic and electric fields influences the dynamics of PDs. The measurement technique allowed to detect quantitatively the effect of magnetic fields on PDs in two representative arrangements: in gaseous void in dielectric material and in corona point-plane setup. Measurements in both configurations have revealed amplification of PDs intensity. The quantitative comparison of PDs evolution in the magnetic field is a novel aspect shown in this paper. Combination of phase resolved images and time-sequence intensity diagrams obtained at magnetic field switching allowed to visualize and determine quantitatively this impact. This effect is attributed to the extension of the charged particle trajectory and the amplification of the electron energy due to acceleration. Thus, the investigated impact of a magnetic field can be perceived as an additional element that influences the PD dynamics.

Nigel Oscar Weiss. 16 December 1936—24 June 2020

Nigel Weiss was an astrophysicist and applied mathematician, born in South Africa but based in Cambridge for most of his career. He made a number of important contributions to the study of sunspots, where he produced a detailed model of their complex structure. He also made important contributions to theory of the solar 22-year magnetic cycle, using pioneering numerical modelling and drawing attention to the dynamical effects of symmetry breaking and of historic proxy data through observations of radioactive isotopes in tree rings and ice cores. A major part of his work was the numerical and theoretical investigation of many aspects of the interaction of magnetic fields with thermal convection in the Sun and stars. The numerical studies in particular were pioneering in the context of computer resources at that time. He led a talented group of students and postdocs, many of whom have held senior positions in UK and US universities. He combined great physical insight with expertise in numerical computation, nonlinear dynamics and bifurcation theory, and was an inspirational supervisor and mentor, combining high academic standards with an open generous nature. Apart from his work he had a strong interest in twentieth-century art and served on the National Gallery Consultative Group for many years.

Effect of magnetic and electric field interaction on non-classical properties of graphene coherent states

Effect of magnetic and electric field interaction on non-classical properties of graphene coherent states

A study of pressure-driven flow in a vertical duct near two current-carrying wires using finite volume technique.

For heating, ventilation or air conditioning purposes in massive multistory building constructions, ducts are a common choice for air supply, return, or exhaust. Rapid population expansion, particularly in industrially concentrated areas, has given rise to a tradition of erecting high-rise buildings in which contaminated air is removed by making use of vertical ducts. For satisfying the enormous energy requirements of such structures, high voltage wires are used which are typically positioned near the ventilation ducts. This leads to a consequent motivation of studying the interaction of magnetic field (MF) around such wires with the flow in a duct, caused by vacuum pump or exhaust fan etc. Therefore, the objective of this work is to better understand how the established (thermally and hydrodynamically) movement in a perpendicular square duct interacts with the MF formed by neighboring current-carrying wires. A constant pressure gradient drives the flow under the condition of uniform heat flux across the unit axial length, with a fixed temperature on the duct periphery. After incorporating the flow assumptions and dimensionless variables, the governing equations are numerically solved by incorporating a finite volume approach. As an exclusive finding of the study, we have noted that MF caused by the wires tends to balance the flow reversal due to high Raleigh number. The MF, in this sense, acts as a balancing agent for the buoyancy effects, in the laminar flow regime.

Sensing Magnetic Field and Intermolecular Interactions in Diamagnetic Solution Using Residual Dipolar Couplings of Zephycandidine

An unusual residual dipolar coupling of methylene protons was recorded in NMR spectra because aromatic zephycandidine has preferential orientation at the external magnetic field. The observed splitting contains contribution from the dipole-dipole D-coupling and the anisotropic component of J-coupling. Absolute values of the anisotropy of magnetic susceptibility |Δχax| are larger for protic solvents because of the hydrogen-bonding compared to aprotic solvents for which polar and dispersion forces are more important. The energy barrier for the reorientation due to hydrogen-bonding is 1.22 kJ/mol in methanol-d4, 0.85 kJ/mol in ethanol-d6 and 0.87 kJ/mol in acetic acid-d6. In dimethyl sulfoxide-d6, 1.08 kJ/mol corresponds to the interaction of solvent lone pair electrons with π-electrons of zephycandidine. This energy barrier decreases for acetone-d6 which has smaller electric dipole moment. In acetonitrile-d3, there is no energy barrier which suggests solvent ordering around the solute due to the solvent-solvent interactions. The largest absolute values of the magnetic anisotropy are observed for aromatic benezene-d6 and tolune-d8 which have their own preferential orientation and enhance the order in the solution. The magnetic anisotropy of "isolated" zephycandidine, not hindered by intermolecular interaction could be estimated from the correlation between Δχax and cohesion energy density.

To management of the properties of materials for the subsequent optimization of life cycles of products

Objective. The aim of the study is to establish the possibility of recognizing the characteristics of the internal state and confirm the influence of atomic or molecular bonds on the change of certain indicators of physical and mechanical properties of non-magnetic metallic (aluminum, copper) and non-metallic (polymeric) materials. Methods. The research is carried out on the basis of magnetic resonance using neodymium magnets and electric current modulated by white noise signal, as well as with the help of two neodymium magnets. Results. When using neodymium magnets and electric current modulated by a white noise signal in the range of 15-20000 Hz to create the effect of magnetic resonance for non-magnetic metallic materials, an increase in strength is observed until peak values are reached with a gradual decrease to the average value. The interaction of magnetic fields of neodymium magnet and electric current occurs in the body of samples at subcrystalline and subatomic levels. Therefore, this effect is explained by the fact that as a result of vibrations in the material there is a compaction of dislocations. At the moment of change of rest friction to sliding friction, the dislocation accumulation barrier is destroyed, after which the process is repeated again. When two neodymium magnets are used to create the effect of magnetic resonance for textolite and Plexiglas, i.e. for a group of non-metallic materials, the theory of a simultaneous decrease in entropy in the form of an increase in orderliness, namely the orderliness of domains and compaction of dislocations, with an increase in strength is confirmed. The influence of magnetic resonance treatment on changes occurring at the atomic and molecular level in polymeric materials is confirmed. Scientific novelty. The established dependences indicate a connection between the strengthening of the material and the improvement of the quality of its structure: ordering of domains and compaction of dislocations created by magnetic resonance. Practical significance. The obtained data give grounds for the development of a complex method of influence on a number of parameters of physical and mechanical properties using magnetic resonance based on neodymium magnets for influence and the possibility of predicting the life cycle.

Open bottom mesons in magnetized matter: Effects of (inverse) magnetic catalysis

In-medium masses of the pseudoscalar and vector open bottom mesons ([Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text], [Formula: see text], [Formula: see text]) are studied in the magnetized nuclear matter by considering the effects of Dirac sea, within the chiral effective model. The mass modifications arise due to the interactions of the open bottom mesons with the nucleons and the scalar mesons, calculated in terms of the scalar and number densities of the nucleons and the scalar fields fluctuations, within the chiral model. The effects of the magnetized Dirac sea lead to the considerable changes in the scalar fields with increasing magnetic field, which are related to the condensates of light quark–antiquark pairs. There is observed to be a (reduction) enhancement in the QCD light quark condensates with rising magnetic field, a phenomenon called (inverse) magnetic catalysis. The contribution of the magnetic field on the Fermi sea of nucleons is also taken into account through protons Landau energy levels and anomalous magnetic moments (AMMs) of the nucleons. The additional contribution of the lowest Landau level for the charged mesons is taken into account. In the presence of an external magnetic field, the spin–magnetic field interaction between the longitudinal component of the vector mesons and the pseudoscalar mesons ([Formula: see text], [Formula: see text] and [Formula: see text]) are studied, which lead to level repulsion between their masses with increasing magnetic field. The magnetic fields are observed to have significant contribution on the masses of the open bottom mesons through the Dirac sea effects taking into account the AMMs of nucleons. In vacuum, appreciable medium modifications are obtained due to the magnetized Dirac sea contribution with nonzero nucleonic AMMs.

Radiation Effects on Inclined Magnetohydrodynamics Mixed Convection Boundary Layer Flow of Hybrid Nanofluids over a Moving and Static Wedge

Nowadays, hybrid nanofluids play an important role in heat transfer systems. They are a good alternative to increase the efficiency of heat transfer and save the energy. Thermal radiation and mixed convection flow of hybrid nanofluids past a permeable moving and stationary wedge were studied in this research. This research uses water as a base fluid to investigate the effects of silver (Ag) and magnesium oxide (MgO) nanoparticles. Similarity transformation techniques are used to convert the partial differential equations of hybrid nanofluids to ordinary differential equations, which is then solved numerically by applying the implicit finite difference Keller box method. The results of the research are illustrated graphically to show the behavior of velocity and temperature profiles, as well as skin friction and Nusselt number. Increasing the parameters of the aligned magnetic field, magnetic field interaction, mixed convection, and wedge angle parameter results in higher velocity profiles but lower temperature profiles. As the radiation parameter and the nanoparticle volume fraction increase, the temperature rises and the velocity decreases. With the exception of the radiation parameter, the skin friction and Nusselt number increase as the alignment angle of the magnetic field, the interaction of the magnetic field, the mixed convection, the wedge angle parameter, and the volume fraction of nanoparticle Ag and MgO rise. As a result of these findings, the velocity profiles and Nusselt numbers of moving wedges are higher, but the temperature profiles and skin friction are lower than those of stationary and moving against flow wedges. In addition, a comparison with previously published research is presented, with excellent agreement discovered. The results of this research will contribute to the field of knowledge in mathematics by bringing additional information for mathematician interested in future research on hybrid nanofluids.

Hydrogenic impurity effect on the optical properties of Ga1-xAlxAs quantum wire under terahertz field

In this study, the effect of impurity factor on the optical absorption coefficients, refractive index changes, second harmonic generation, and third-harmonic generation for the intersubband transitions is explored between the electronic states of Ga1-xAlxAs quantum wire initiated by the symmetric parabolic potential. The system is conquered by the presence of an intense electric field, magnetic field, and Rashba spin-orbit interaction. For the linear and non-linear optical absorption coefficients, refractive index, second harmonic generation, and third harmonic generation coefficient, the analytical expressions are obtained with the assistance of the compact density-matrix approach. The arithmetical outcomes illustrate the optical properties are significantly intuitive to the concentration of impurity and can be controlled by this parameter. The variation in the magnitude and position of peaks via impurity factor indicates the opportunity in the mechanism of optical non-linearity in the quantum wire and also, helps in the optical non-linearity tuning which has device application.

An observer design for the flux of line start permanent magnet synchronous motors

The permanent magnet flux is an important model parameter that determines the operation of the line start permanent magnet synchronous motor. It is degraded with operating time due to the permanent magnet demagnetization which is principally caused by the armature magnetic field interaction and operating temperature. This paper introduces an observer design study aimed at estimating the permanent magnet flux of the line start permanent magnet synchronous motor from the measurement of stator currents. Derived from the mathematical description in the dq0 reference frame, a model of the motor with state variables of stator currents, magnetic fluxes and rotor angular frequency is considered. Model analysis and with a new flux variable setting allow an estimation of the rotor flux through the open loops from the stator currents. The observer is then designed with a constant gain for the system with states of stator currents and permanent magnet flux. Simulation confirms the efficiency and robustness of the designed observer.

Critical Current and AC Ripple Loss Analysis of a Global Self-Shielding HTS DC Cable Made of Filament REBCO Tapes

For the high-temperature superconducting dc cable with the same current orientation in every layer, the maximum magnetic field generally arises in the outermost layer. When the cable transmits a large current, the generated strong magnetic field will make the utilization rate of tapes extraordinarily low. The current direction of two neighboring layers in the self-shielding sandwich cable is inverse, which can whittle the magnetic field interaction of each layer, so as to minish the critical current attenuation of REBCO tape. The previous global self-shielding dc cable adjusts the current distribution between layers to homogenize the magnetic field. However, this article proposes a new global self-shielding dc cable made of filament REBCO tapes, which adjusts the current distribution in each layer. The uniformity of magnetic field can be improved further by using filament tapes to wind the cable. In this article, <bold xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>T-A</i></b> formulation is adopted to study the critical current and ac ripple loss of global self-shielding sandwich cables made of filament REBCO tapes in detail. The simulation results demonstrate that the structure made of filament tapes has better performance than the previous global self-shielding structure.

Theoretical analysis of entropy production in exothermic/endothermic reactive magnetized nanofluid flow through curved porous space with variable permeability and porosity

In current analysis, flow of magnetized nanofluids in porous curved stretchable surface with variable characteristics has been inspected by imposing the thermal radiation, and activation energy. The exothermic/endothermic reactive effect is included along with Buongiorno nanofluid model to investigate the thermal performance more extensively. The Lorentz force characteristics that cause the interaction of magnetic field with nanoliquid motion is further investigated. Additionally, production of entropy in the porous curved system because of irreversible process has been considered here. The modeled systems for considered model are firstly transformed into ODEs via appropriate variables and then computed by employing NDSolve technique using tool of Mathematica. Flow fields variation against relevant variables is inspected via tables and sketches. The key outcome of analysis is that, the entropy rate upsurges for higher local inertia parameter, radiation variable and Brinkman number.

Magnetic manipulation of discontinuous ferromagnetic fibers in viscous fluids: Dynamics of single fiber alignment

AbstractThe method of fiber morphology manipulation using magnetic field interaction is proposed for single discontinuous steel fibers dispersed in viscous fluids and subjected to low magnetic fields. The goal of this study was to investigate the fiber behavior under different test conditions. The effects of the fluid viscosity, the fiber aspect ratio and the strength of the magnetic field on the dynamics of fiber alignment were analyzed. In‐plane magnetic alignment tests with a single fiber were carried out to avoid fiber‐fiber interactions and fiber clustering. Based on the experimental results, a model to predict ferromagnetic fiber alignment caused by a static unidirectional magnetic field was provided. Existing models focus on the different torques occurring in the realignment process. The presented model is based on single‐term exponential equations and considers all previously mentioned variables. It is shown that a good agreement between experimental data and fiber realignment predictions for single fibers is achieved.