Rotating Magnetic Field Research Articles

Effect of rotating magnetic field (RMF) on the microstructure and mechanical properties of Al–2%Fe eutectic alloy

The effect of rotating magnetic field (RMF) on the solidification of microstructures and mechanical properties of Al–2%Fe (wt.%) eutectic alloy are studied in this manuscript. SEM, EDS and TEM techniques are adopted to analyze the evolution of Al3Fe intermetallics morphology in Al–2%Fe eutectic alloy. Without RMF, the length of Al3Fe intermetallics with large plate-like and long acicular shape are about 173 μm and 189 μm, respectively. With the RMF, the Fe-rich intermetallics is refined due to collision and shear action by the Lorentz force. When the intensity of the RMF reaches to 80 V, the average length of acicular Al3Fe intermetallics is 17 μm, and the average diameter of plate-like Al3Fe is 40 μm. However, when the intensity reaches to 100 V, the Al3Fe intermetallics coarsens. With the introduction of RMF, the tensile strength and elongation of the Al–2%Fe alloy increase accordingly. When the intensity of the RMF is 80V, the maximum tensile strength and elongation are 94.24 MPa and 13.37%, respectively. The influential mechanism of RMF is also discussed in this manuscript.

Modeling and optimisation of magnetic field assisted electrochemical spark drilling using hybrid technique

ABSTRACT The present paper focuses on the application of a hybrid methodology for multi-objective optimisation (MOO) of an in-house deigned and fabricated magnetic field-assisted electrochemical spark drilling (MF-ECSD) process where an electromagnetic unit is added in the setup to create magnetic field of different intensities. The process combines Taguchi methodology (TM) with response surface methodology (RSM) for modelling and grey relational analysis (GRA) with principal component analysis (PCA) methodology for MOO. TM is utilised as the core values in RSM to create the second-order response model, and it is used to find the optimum level of input parameters, namely, voltage (V), electrolyte concentration (EC), tool rotational speed (TRS) and magnetic field intensity (MFI). Material removal rate (MRR), machining depth (MD) and overcut (OC) are the responses. PCA is used to calculate the weight associated with each quality feature.

Switchbacks in the Young Solar Wind: Electron Evolution Observed inside Switchbacks between 0.125 au and 0.25 au

Switchbacks are localized deviations from the nominal Parker spiral field in the solar wind. In this study, we investigate the electron distributions inside switchbacks, focusing primarily on the suprathermal (halo and strahl) populations. We explore electron parameters in relation to the angle of rotation of the magnetic field from radial to determine whether electron distributions observed within switchbacks have any differences from those outside of switchbacks. Our observations reveal several trends in the suprathermal electron populations inside switchbacks. We find that the sunward deficit in the electron velocity distribution function typically observed near the Sun is filled in at larger rotation angles. This results in the suprathermal electron density and heat flux in the antistrahl direction changing from a negative to a positive value. On many days, we also observe a positive correlation between the halo density and rotation angle, and this may suggest that the growth of the halo may fill in the sunward deficit. We also find that strahl distributions have an increased average angular spread at large magnetic field rotation angles. The increase in suprathermal electron flux in the antistrahl direction, and the increase in strahl width, together could suggest that enhanced scattering occurs inside switchbacks. Electron core beta values tend to increase with the magnetic field rotation angle, mainly due to a decrease in magnetic pressure. An increase in electron beta may favor the growth of instabilities inside switchbacks. The Parker Solar Probe observations therefore support an enhanced role for wave–particle interactions in switchbacks.

Effect of rotating magnetic field on the microstructure and properties of Sn-Ag-Sb lead-free solder alloys

PurposeThe purpose of this paper is to study the microstructure and properties of Sn-3.5Ag and Sn-3.5Ag-0.5Sb lead-free solder alloys with and without a rotating magnetic field (RMF).Design/methodology/approachOptical microscopy, scanning electron microscopy and X-ray diffraction were used to analyze the effect of an RMF on the microstructure of the solders. Differential scanning calorimetry was used to study the influence of the RMF on the thermal characteristics of the solders. The mechanical properties of the alloys were determined by tensile measurements at different strain rates.FindingsThe ß-Sn grains and intermetallic compounds for the Sn-3.5Ag and Sn-3.5Ag-0.5Sb lead-free solder alloys were refined under an RMF, and the morphology of the ß-Sn grains changed from dendritic to equiaxed. The pasty range was significantly reduced under an RMF. The ultimate tensile strength (UTS) of Sn-3.5Ag improved under the RMF, whereas the UTS of Sn-3.5Ag-0.5Sb decreased slightly. The addition of Sb to the Sn-3.5Ag alloy significantly enhanced the UTS and elongation (El.%) of the samples. The UTS of the solder increased with increasing strain rate.Originality/valueThe results revealed that the application of RMF in the molten alloy had a significant effect on its microstructure and mechanical properties. The thermal characteristics of the Sn-3.5Ag and Sn-3.5Ag-0.5Sb solder alloys were improved under the RMF. This research is expected to fill a knowledge gap regarding the behaviour of Sn-Ag solder alloys under RMF.

Improvement of radial confinement of plasma via applying rotating magnetic fields

We report a novel method to control the plasma radial transport, namely, applying a rotating magnetic field (RMF) to create azimuthal shear flow, which is found to change the transport from Bohm to classical diffusion if the ratio of magnetization parameter to penetration parameter is greater than 1.5. Upon application of the RMF, the peak density is observed to increase by 33% above the normal value. Specifically, the ratio increases from 4 × 1018 m−3 to 6 × 1018 m−3, and the corresponding density gradient length changes from 11 cm to 6 cm, or the steepness increases by about a factor of 2. Further increasing the RMF strength cannot steepen the density further. The results suggest the RMF can be a non-intrusive method to control the radial transport and hence the plasma density profile.

Simulating single-particle dynamics in magnetized plasmas: The RMF code.

The RMF (Rotating Magnetic Field) code is designed to calculate the motion of a charged particle in a given electromagnetic field. It integrates Hamilton's equations in cylindrical coordinates using an adaptive predictor-corrector double-precision variable-coefficient ordinary differential equation solver for speed and accuracy. RMF has multiple capabilities for the field. Particle motion is initialized by specifying the position and velocity vectors. The six-dimensional state vector and derived quantities are saved as functions of time. A post-processing graphics code, XDRAW, is used on the stored output to plot up to 12 windows of any two quantities using different colors to denote successive time intervals. Multiple cases of RMF may be run in parallel and perform data mining on the results. Recent features are a synthetic diagnostic for simulating the observations of charge-exchange-neutral energy distributions and RF grids to explore a Fermi acceleration parallel to static magnetic fields.

Rotational Discontinuities in the Magnetopause of an Open Magnetosphere

AbstractIn this paper, we analyze the fine structure of rotational discontinuities (RDs) in the magnetopause of an open magnetosphere using four‐point magnetic field measurements recorded by the Magnetospheric MultiScale mission. An RD is commonly observed within the magnetopause when reconnection occurs in the magnetopause. Furthermore, an RD usually occurs closer to the magnetosheath side of the magnetopause. The magnetic structure of RD is usually much thinner than 110 km. The magnetic field rotation maxima and magnetic strength minima are within the RD. The radius of curvature of the magnetic field lines reaches a minimum in the RD (∼83–1,491 km). In addition, the radius of curvature of the magnetic field lines of the RD is usually much larger than the thickness of the magnetic structure of the RD, indicating that the magnetic field lines almost lie in the RD. Generally, a field‐aligned current dominates in the RD.

Four bright eclipsing binaries with γ Doradus pulsating components: CM Lac, MZ Lac, RX Dra, and V2077 Cyg

ABSTRACT The study of pulsating stars in eclipsing binaries holds the promise of combining two different ways of measuring the physical properties of a star to obtain improved constraints on stellar theory. Gravity (g) mode pulsations such as those found in γ Doradus stars can be used to probe rotational profiles, mixing, and magnetic fields. Until recently few γ Doradus stars in eclipsing binaries were known. We have discovered g-mode pulsations in four detached eclipsing binary systems from light curves obtained by the Transiting Exoplanet Survey Satellite (TESS) and present an analysis of their eclipses and pulsational characteristics. We find unresolved g-mode pulsations at frequencies 1–1.5 d−1 in CM Lac, and measure the masses and radii of the component stars from the TESS data and published radial velocities. MZ Lac shows a much richer frequency spectrum, including pressure modes and tidally excited g-modes. RX Dra is in the northern continuous viewing zone of TESS so has a light-curve covering a full year, but shows relatively few pulsation frequencies. For V2077 Cyg we formally measure four pulsation frequencies, but the available data are inadequate to properly resolve the g-mode pulsations. V2077 Cyg also shows total eclipses, with which we obtain the first measurement of the surface gravity of the faint secondary star. All four systems are bright and good candidates for detailed study. Further TESS observations are scheduled for all four systems, with much improved temporal baselines in the cases of RX Dra and V2077 Cyg.

Coupled Effects of Using Magnetic Field, Rotation and Wavy Porous Layer on the Forced Convection of Hybrid Nanoliquid Flow over 3D-Backward Facing Step.

In the present study, the effects of using a corrugated porous layer on the forced convection of a hybrid nanofluid flow over a 3D backward facing step are analyzed under the coupled effects of magnetic field and surface rotation. The thermal analysis is conducted for different values of the Reynolds number (Re between 100 and 500), the rotational Reynolds number (Rew between 0 and 2000), the Hartmann number (Ha between 0 and 15), the permeability of the porous layer (the Darcy number, Da between and ) and the amplitude (ax between 0.01 ap and 0.7 ap) and wave number (N between 1 and 16) of the porous layer corrugation. When rotations are activated, the average Nusselt number (Nu) and pressure coefficient values rise, while the increment of the latter is less. The increment in the average Nu is higher for the case with a higher permeability of the layer. When the corrugation amplitude and wave number are increased, favorable impacts of the average Nu are observed, but at the same time pressure coefficients are increased. Successful thermal performance estimations are made by using a neural-based modeling approach with a four input-two output system.

V889 Her: abrupt changes in the magnetic field or differential rotation?

We have applied Zeeman-Doppler imaging (ZDI) to an extensive spectropolarimetric HARPSpol data set of the magnetically active young solar analogue V889 Her, covering 35 spectra obtained during six nights in May 2011. The data set allows us to study Stokes V profiles of the star at almost identical rotational phases, separated by one or more stellar rotations. We use these data to study if the line profiles evolve from one rotation to the next, and find that some evolution does indeed occur. We consider two possible explanations for this: abrupt changes in the large-scale magnetic field or differential rotation. We find it quite difficult to distinguish between the two alternatives using ZDI alone. A strong differential rotation could, however, explain the changes in the line profiles, so we conclude that it must be present, and the abrupt magnetic field evolution is left uncertain. Commonly, rapidly rotating stars are assumed to have only weak differential rotation. If the strong differential rotation of V889 Her is indeed present, as has been found in other studies as well, it could indicate that the theoretical and numerical results of differential rotation still need to be revised. The rapid changes that may have occurred in the magnetic field indicate that one should be quite cautious when interpreting ZDI maps constructed from data over long time intervals.

Plume Performance of Electrodeless Plasmoid Electromagnetic Propulsion

Electrodeless plasmoid electromagnetic propulsion was recently proposed for robotic and crewed space missions. This electrodeless construction has the potential to solve the existing limitations, such as duration and low efficiency. The rotating magnetic field (RMF) excitation and Lorentz Force acceleration mechanism of the plasmoid has the advantage of producing a highly variable thrust and a discrete impulse. In this article, the plume performance of the proposed propulsion primer was presented for the first time and evaluated by varying the RMF input power, bias magnetic field, and flow rate, while the power of the preionization source and discharge propellant are held constant. The RMF excitation and Lorentz Force acceleration mechanism of the plasmoid were confirmed by the plume performance and discharge characteristics. The stable discharge in Ar, N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , and Xe demonstrated the potential application of this electrodeless technology in future multipropellant high-power propulsion applications. The phase angle of 90° in the RMF coil was essential for the higher performance of the plasma plume. The propulsion thrust and specific impulse were estimated to be 16.1 mN and 1600 N <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\cdot $ </tex-math></inline-formula> s, respectively, at 1.2 kW from the initial test conducted using the Langmuir probe, assuming a complete penetration of RMF in the plasma.

The Effect of Strong Magnetic Field and Engine Rotation on Fuel Consumption and Exhaust Gas Emissions for Gasoline Engines

An Iincreasing number of means of transportation in various cities causes air pollution. There have been many studies to reduce air pollution due to motorized vehicles. One of them relates to the fuel line. The purpose of this study was to determine the relationship between the strength of the magnetic field in the fuel line on fuel consumption and exhaust emissions. The research method uses a pure experimental method. The independent variables are magnetic field strength (51, 102, 152, 202, and 249 gauss) in the fuel line and engine speed (1500 rpm, 2500 rpm, 3500 rpm and 4500 rpm). The dependent variable is fuel consumption (ltr/hour) and exhaust emissions. Test was carried Fourier transform infrared out to determine the chemical compound group of the fuel. The results showed that the highest concentration of transmittance at a wavelength of 2850 cm־¹ - 2970 cm־¹ was 77.75% with a magnetic field strength of 249 gauss, when compared to standard conditions it was 33.05%. At a strong magnetic field of 249 gauss with a rotation of 2500 rpm, it can save fuel consumption of 0.2 liters/hour. In addition, it can also reduce the level of exhaust gas O₂ by 4.16% (3500 rpm), CO gas by 1.29% (2500 rpm), CO₂ gas by 5.2% (1500 rpm) and HC gas by 215.66%. (4500 rpm).

A Novel Dual Helical Magnetorheological Fluid Micro-Robot

To address the problem of flexible drive control of gastrointestinal (GI) tract micro-capsule robot posture, a novel dual helix magnetorheological fluid (MRF) micro-robot (DHMRFMR) is proposed and developed in this paper. Based on the mechanical properties of magnetorheological fluid, the relationship model of magnetic field force is obtained, and the thrust model is established. Double micro DC deceleration motor is used to drive the two ends of the helical actuator to make the DHMRFMR forward and backward, by changing the external magnetic field rotation speed, direction and distance, adjust the attitude direction of the robot. Numerical simulation software ANSYS is used to analyze the motion law of external fluid of DHMRFMR, and the visualization of fluid velocity and pressure distribution is realized. The front-end helix actuator can change the flow path of the fluid, and the middle and tail of the DHMRFMR bear less pressure, which improves the stability and flexibility of the robot. The novel DHMRFMR is suitable for internal drive in bending environment, and has a good application prospect in biomedical engineering field in human intestinal unstructured environment.

Modelling magnetically channeled winds in 3D – I. Isothermal simulations of a magnetic O supergiant

ABSTRACT In this paper we present the first set of 3D magnetohydrodynamic (MHD) simulations performed with the riemann geomesh code. We study the dynamics of the magnetically channeled winds of magnetic massive stars in full three dimensions using a code that is uniquely suited to spherical problems. Specifically, we perform isothermal simulations of a smooth wind on a rotating star with a tilted, initially dipolar field. We compare the mass-loss, angular momentum loss, and magnetospheric dynamics of a template star (with the properties that are reminiscent of the O4 supergiant ζ Pup) over a range of rotation rates, magnetic field strengths, and magnetic tilt angles. The simulations are run up to a quasi-steady state and the results are observed to be consistent with the existing literature, showing the episodic centrifugal breakout events of the mass outflow, confined by the magnetic field loops that form the closed magnetosphere of the star. The catalogued results provide perspective on how angular-momentum loss varies for different configurations of rotation rate, magnetic field strength, and large magnetic tilt angles. In agreement with previous 2D MHD studies, we find that high magnetic confinement reduces the overall mass-loss rate, and higher rotation increases the mass-loss rate. This and future studies will be used to estimate the angular-momentum evolution, spin-down time, and mass-loss evolution of magnetic massive stars as a function of magnetic field strength, rotation rate, and dipole tilt.

Some Preliminary Results to Eradicate Leukemic Cells in Extracorporeal Circulation by Actuating Doxorubicin-Loaded Nanochains of Fe3O4 Nanoparticles

Leukemia is a non-solid cancer which features the malignant proliferation of leukocytes. Excessive leukocytes of lesions in peripheral blood will infiltrate organs, resulting in intumescence and weakening treatment efficiency. In this study, we proposed a novel approach for targeted clearance of the leukocytes in the peripheral blood ex vivo, which employed magnetic nanochains to selectively destroy the leukocytes of the lesions. The nanochains were doxorubicin-loaded nanochains of Fe3O4 nanoparticles which were fabricated by the solvent exchange method combined with magnetic field-directed self-assembly. Firstly, the nanochains were added into the peripheral blood during extracorporeal circulation and subjected to a rotational magnetic field for actuation. The leukocytes of the lesion were then conjugated by the nanochains via folic acid (FA) targeting. Finally, the rotational magnetic field actuated the nanochains to release the drugs and effectively damage the cytomembrane of the leukocytes. This strategy was conceptually shown in vitro (K562 cell line) and the method’s safety was evaluated in a rat model. The preliminary results demonstrate that the nanochains are biocompatible and suitable as drug carriers, showing direct lethal action to the leukemic cells combined with a rotational magnetic field. More importantly to note is that the nanochains can be effectively kept from entry into the body. We believe this extracorporeal circulation-based strategy by activating nanochains magnetically could serve as a potential method for leukemia treatment in the future.

Magneto-Optical Imaging of Arbitrarily Distributed Defects in Welds under Combined Magnetic Field

Using the traditional magneto-optical detection methods, micro-weld defects parallel with the magnetic field direction may be overlooked. In order to overcome this, a non-destructive testing method based on magneto-optical imaging under a vertical combined magnetic field (VCMF) is proposed. To demonstrate this, the experimental results of the magneto-optical imaging of weld defects excited by a vertical combined magnetic field (VCMF) or parallel combined magnetic field (PCMF) are compared with those of traditional magnetic fields (constant magnetic field (CMF), alternating magnetic field (AMF), and rotating magnetic field (RMF)). It is found that the magneto-optical imaging under a VCMF can accurately detect weld defects of any shape and distribution. In addition, the center difference method is used to eliminate the influence of noise on the defect contour extraction of magneto-optical images, and the active contour of weld defects in the magneto-optical images is extracted. The results show that many noises can be identifiedby the robustness of the level set method, operating in low-pass filtering, so that much information that is usually lost can be retained.

Effect of pine essential oil and rotating magnetic field on antimicrobial performance

This work presents the results ofa study which concerns the influence of rotating magnetic field (RMF) on the antibacterial performance of commercial pine essential oil. A suspension of essential oil in saline solution and Escherichia coli were exposed to the rotating magnetic Afield (the frequency of electrical current supplied by a RMF generator f = 1–50 Hz; the averaged values of magnetic induction in the cross-section of the RMF generator B = 13.13 to − 19.92 mT, time of exposure t = 160 min, temperature of incubation 37 °C). The chemical composition of pine (Pinus sylvestris L.) essential oil was determined by gas chromatography coupled with mass spectrometry (GC–MS). The main constituents were α-pinene (28.58%), β-pinene (17.79%), δ-3-carene (14.17%) and limonene (11.58%). The present study indicates the exposition to the RMF, as compared to the unexposed controls causing an increase in the efficacy of antibacterial properties of pine oil. We have shown that rotating magnetic fields (RMF) at a frequency, f, between 25 Hz to and 50 Hz increased the antimicrobial efficiency of oil a concentration lower than 50%.

Antimicrobial properties of pristine and Pt-modified titania P25 in rotating magnetic field conditions

Effective and cheap water purification is one of the most important tasks facing humanity. Among various methods of water treatment, heterogeneous photocatalysis is probably most recommended. However, the application of artificial sources of irradiation results in high investment and operating costs. Accordingly, either vis-responsive photocatalysts or different ways of photocatalyst activation should be developed. In the present study, rotating magnetic field (RMF) has been tested to inactivate gram-positive (Staphylococcus epidermidis) and gram-negative (Escherichia coli) bacteria in the presence of pristine and Pt-modified titania P25 photocatalyst. Liquid cultures of the bacteria have been exposed to the titania and RMF (RMF frequency of 1–50 Hz, RMF magnetic induction of ca. 19.92 mT, 180 min exposure time, temperature of incubation at 37 °C). It has been found that highly active titania photocatalyst might also work in the absence of photoirradiation but under RMF. Moreover, its modification with platinum besides highly improved photocatalytic activity (tested for two model reactions of oxidative decomposition of acetic acid and anaerobic dehydrogenation of methanol under UV/vis irradiation) results in significant enhancement of antimicrobial effect under RMF. Additionally, photocatalysts with larger content of oxidized forms of platinum show higher antimicrobial activity, and thus it is proposed that platinum oxides are more active than zero-valent platinum under RMF. This study provides evidence of antimicrobial effect of titania without photoirradiation, indicating that RMF might efficiently activate photocatalyst.

Regulatory and Enterotoxin Gene Expression and Enterotoxins Production in Staphylococcus aureus FRI913 Cultures Exposed to a Rotating Magnetic Field and trans-Anethole.

The study aimed to examine the influence of a rotating magnetic field (RMF) of two different frequencies (5 and 50 Hz) on the expression of regulatory (agrA, hld, rot) and staphylococcal enterotoxin (SE—sea, sec, sel) genes as well as the production of SEs (SEA, SEC, SEL) by the Staphylococcus aureus FRI913 strain cultured on a medium supplemented with a subinhibitory concentration of trans-anethole (TA). Furthermore, a theoretical model of interactions between the bacterial medium and bacterial cells exposed to RMF was proposed. Gene expression and SEs production were measured using quantitative real-time PCR and ELISA techniques, respectively. Based on the obtained results, it was found that there were no significant differences in the expression of regulatory and SE genes in bacteria simultaneously cultured on a medium supplemented with TA and exposed to RMF at the same time in comparison to the control (unexposed to TA and RMF). In contrast, when the bacteria were cultured on a medium supplemented with TA but were not exposed to RMF or when they were exposed to RMF of 50 Hz (but not to TA), a significant increase in agrA and sea transcripts as compared to the unexposed control was found. Moreover, the decreased level of sec transcripts in bacteria cultured without TA but exposed to RMF of 50 Hz was also revealed. In turn, a significant increase in SEA and decrease in SEC and SEL production was observed in bacteria cultured on a medium supplemented with TA and simultaneously exposed to RMFs. It can be concluded, that depending on SE and regulatory genes expression as well as production of SEs, the effect exerted by the RMF and TA may be positive (i.e., manifests as the increase in SEs and/or regulatory gene expression of SEs production) or negative (i.e., manifests as the reduction in both aforementioned features) or none.

Speed Estimation of an Asynchronous Motor with Feed Forward Neural Network

Abstract: AC asynchronous motors are the most frequent motors used in industrial motion control systems as well as in mainpowered domestic appliances. AC asynchronous motors provide several advantages, including a simple and durable construction, low cost, low maintenance, and direct connection to an AC power source. On the market, there are many different types of AC asynchronous motors. Diverse motors are suitable for various applications. Like other motors, an AC asynchronous motor contains a stator that is fixed on the outside and a rotor that spins within, separated by a precisely designed air gap. Almost all electric motors use magnetic field rotation to spin their rotors. Asynchronous motors are the most commonly utilized electromechanical machinery in industrial applications. There have been several research on their control, as well as a variety of approaches for achieving high-performance speed drivers. The properties of asynchronous motors alter with time and under different operating situations. Even though much research has gone into developing artificial neural network techniques to estimate the speed of an asynchronous motor and some of the parameters such as flux and torque, there hasn't been much work done on asynchronous motor speed estimation using artificial neural networks. The main purpose of this paper is to build a speed estimator for an asynchronous motor using a feed-forward artificial neural network. A mathematical model for the asynchronous motor is developed and implemented in Matlab. A speed estimator is then developed using a feed-forward neural network and coupled to the asynchronous motor to estimate its speed. After that, simulations are done to see how well the proposed speed estimator performed. Keywords: Space Vector Modulation PWM (SVPWM), Artificial Neural Networks (ANN), magnet Permanent magnet Synchronous Motor (PMSM)