Magnitude Of Magnetic Flux Research Articles

Electron confinement investigation in low beta magnetic polywell configurations

This study uses numerical simulations to investigate the effects of magnetic field topology resulting from various polywell fusion setup configurations, including the cube configuration (6 coils), dodecahedron configuration (12 coils), double-layer configuration (14 coils) and disco configuration (26 coils). The results suggest that increased number of magnetic coils and magnitude of magnetic flux density through increased coil current leads to a longer electron confinement time. This is shown by the increased magnetic flux density and magnetic well width with increasing number of coils. In addition, each configuration is investigated to predict the capacity of electron confinement. Numerical electron injections are applied to each magnetic field topology to determine the decay behavior of electron numbers, from which the electron confinement time is calculated.

BIOIMPACT OF HYPOMAGNETIC FIELDS

Hypomagnetic fields (HMF), or nearly zero magnetic fields, are fields with a value of magnetic flux density lower than the Earth's geomagnetic field. The effects of these so-called weak magnetic fields can manifest in living organisms by influencing biological functions such as the circadian system, calcium balance in cells, DNA methylation, concentration of reactive oxygen species, as well as changes in metabolic and developmental processes. This article describes how HMF affects selected cellular structures through specific exposure parameters, whose selective impact has been verified on the proliferative activity of the yeast strain Saccharomyces cerevisiae. In 25 experiments, the inhibitory effect of a time-varying magnetic field at a level of 0.365 µT was confirmed, which corresponds to the magnitude of magnetic flux density in the vicinity of 100 kV power lines. Global organizations also point out the possible correlation between HMF generated by 50 Hz power lines and various diseases, particularly childhood leukemia.

Electromagnetic Performance Investigation of Rectangular-Structured Linear Actuator with End Ferromagnetic Poles

Saving energy from domestic appliances is a focus in the effort to combat energy challenges. Linear compressors are a more efficient alternative to the traditional compressors used in refrigerators, which account for 20–40% of all residential electricity use. This article investigates the new topology of the moving magnet (MM), dual-stator single-mover linear oscillating actuator (DSSM-LOA) for linear compressor application. Both the stators were C-shaped, with coils looped across their end sides. Two permanent magnets (PMs) that were axially magnetized were housed on the mover. The PM structural shape significantly affected its fabrication cost and magnitude of magnetic flux density (B). The DSSM-LOA makes use of axially magnetized rectangular-shaped PMs because they are inexpensive and generate high electromagnetic (EM) force density. End ferromagnetic core materials were used to improve the magnetic flux, linking from the stator to the mover. All the design parameters were optimized through parametric analysis using the finite parametric sweep method. Parameters present within the three primary parameters (length, height, and depth) that were assumed constants were optimized, and the optimal dimensions were selected based on the EM force. The investigated DSSM-LOA was contrasted with traditional LOA designs, and they showed significant improvement in EM force per ampere, generally named motor constant (MC), MC per PM mass, MC density, cogging force, and stroke. Additionally, the proposed DSSM-LOA had a simple structure and low cost, and it operated in a feasible range of strokes for linear compressor application.

Magnetohydrodynamics analysis of magnetorheological fluid damper

A key feature of magnetorheological fluid is its variability of rheological properties in which upon exposing this fluid, the viscosity of the fluid changes accordingly. Hence this nature can be implemented in various engineering applications. To understand its influence in a magnetorheological (MR) damper, it is essential to study the flow behaviour using computational and numerical methods. The main objective of this work is to estimate the influence of the external magnetic field on the fluid flow velocity inside the damper using magnetohydrodynamic analysis. Finite element analysis, magnetostatic analysis, and magnetohydrodynamic (MHD) analysis have been carried out to investigate the change in the shape of the velocity profile across the flow gap of the monotube MR damper under the various magnitude of magnetic force using the MHD module of ANSYS fluent software. The simulation is conducted by considering laminar, steady-state, and incompressible fluid flow. In finite element analysis, the magnitude of magnetic flux density (MFD) ‘B’ was evaluated at various direct currents. Later, obtained MFD has been applied perpendicular direction to the flow of MR fluid. The effective length of the fluid exposed to the MFD is taken as 2 mm to 28 mm in an overall flow length of 30 mm. The extracted results have shown that the fluid flow velocity reduces with an increase in the magnetic flux density. It has been observed that 10.42 % reduction in velocity upon increasing the magnetic flux density from 0.25 T to 1 T at 75 kPa pressure. The reason for a reduction in velocity is because of variation in the rheological properties of the fluid under the magnetic field, which is very much essential to produce a good damping effect in the MR damper.

The Effect of Magnetic Flux Density Magnitude on Machine Performance

The effect of magnetic flux density magnitude on electromagnetic performance of a double stator permanent magnet synchronous machine is investigated and presented in this study. Finite element analysis method is applied in computing the results. The considered machine variables are: torque, losses, efficiency and electromagnetic power. The results reveal that output performances of a given machine would be affected by the magnitude of its magnetic flux density, particularly under saturation condition. Most promising electric machine characteristics are shown to be obtained from the device when the magnetic flux density magnitude is within 1.5 to 2.0 Tesla. The impact of this flux density amplitude should be taken into consideration during the design and operation of electrical machines, for effective and efficient output delivery. Highest amount of output torque, power and efficiency of 2.61 Nm, 109.46 W and 89.22 % are obtained from the simulated model at flux density amplitude of 1.6 Tesla.

Experimental analysis and numerical simulation of flow behavior of fresh steel fibre reinforced concrete in magnetic field

• A numerical method was developed to investigate flow behavior of steel fibre concrete. • Magnetic flux density, initial position of steel fibre and resistance of mortar affect orientation. • Fluidity along magnetic field direction decreases with increase of magnetic flux density. Fluidity is an important index to describe the performance of fresh concrete, which has a great influence on the transportation and casting process of concrete. By applying a magnetic field to steel fibre reinforced concrete, in which steel fibre can be oriented to improve flow performance and strength. In this paper, the mechanical model of steel fibre in magnetic field was established in EDEM, and the simulations of magnetic field orientation as well as slump of steel fibre concrete were carried out and compared with the experiment. The errors between numerical and experimental results are less than 5%, which confirms the validity of the model. The effects of magnetic flux density and duration on the orientation of steel fibre and the effect of orientation on flow of mortar were analyzed. It was found that the larger the magnetic flux density, the better orientation of steel fibre. And regardless of the magnitude of magnetic flux density, most steel fibres can be oriented in a relatively short time. Due to the effect of gravity, orientation of mortar in the bottom is more difficult than that in the upper. The magnetic flux density, the initial position of the steel fibre and the resistance to the steel fibre affect the final orientation. When the magnetic field direction is horizontal, the fluidity of mortar along the magnetic field direction decreases with the increase of magnetic flux density, while the fluidity along the vertical magnetic field direction increases. The vertical magnetic field has no obvious effect on the fluidity.

A Modified Inverse Vector Hysteresis Model for Nonoriented Electrical Steels Considering Anisotropy for FEA

This paper presents a modified Mayergoyz-based vector hysteresis model to describe the anisotropic material behavior of nonoriented (NO) steels over a wide range of rotational excitations. The proposed model adopts a new representation of a vector Everett function, which is actually an elliptical interpolation motivated by the real anisotropic behavior of NO steel, to deal with the uniaxial anisotropy characteristic, which is especially pronounced at low induction levels. The biaxial anisotropy occurring at high densities is described by a nonlinear coefficient, which is actually a function of the magnitude of magnetic flux density. A systematic identification algorithm is given in detail. The validity of this model is verified through comparison with experimental data under both alternating and rotational excitations. The 2-D finite element analysis (FEA) of incorporating this model into TEAM problem 32 simulation is also illustrated.

Design and Comparison of Magnetically-Actuated Dexterous Forceps Instruments for Neuroendoscopy.

Robot-assisted minimally invasive surgical (MIS) techniques offer improved instrument precision and dexterity, reduced patient trauma and risk, and promise to lessen the skill gap among surgeons. These approaches are common in general surgery, urology, and gynecology. However, MIS techniques remain largely absent for surgical applications within narrow, confined workspaces, such as neuroendoscopy. The limitation stems from a lack of small yet dexterous robotic tools. In this work, we present the first instance of a surgical robot with a direct magnetically-driven end effector capable of being deployed through a standard neuroendoscopic working channel (3.2 mm outer diameter) and operate at the neuroventricular scale. We propose a physical model for the gripping performance of three unique end-effector magnetization profiles and mechanical designs. Rates of blocking force per external magnetic flux density magnitude were 0.309 N/T, 0.880 N/T, and 0.351 N/T for the three designs which matched the physical model's prediction within 14.9% error. The rate of gripper closure per external magnetic flux density had a mean percent error of 11.2% compared to the model. The robot's performance was qualitatively evaluated during a pineal region tumor resection on a tumor analogue in a silicone brain phantom. These results suggest that wireless magnetic actuation may be feasible for dexterously manipulating tissue during minimally invasive neurosurgical procedures.

Uticaj armirano betonskog stuba na raspodelu magnetskog polja mešovitog voda

In this paper, the analysis of magnetic field distribution of overhead mixed power line (20 kV/0.4 kV) supported by reinforced concrete towers, named MNL-12 is presented. The impact of ferromagnetic, conductive parts of the pylons (reinforcing bars, billets and cross arm beams) on magnetic field distribution is investigated. The numerical calculations were performed in COMSOL Multiphysics program package on simplified 2D model. The main goal of the calculations was to examine the impact of currents induced in ferromagnetic conductive parts on magnetic field produced by currents in the power system’s conductors. The calculation results are presented graphically, as the diagrams of the magnetic flux density magnitude distribution in the tower plan, normal to the system’s axe. The calculation results demonstrated that the magnetic field of induced currents decreases the magnetic field produced by the currents of overhead power system.

Efficient wireless charging system for supercapacitor-based electric vehicle using inductive coupling power transfer technique

Wireless charging has become an emerging challenge to reduce the cost of a conventional plug-in charging system in electric vehicles especially for supercapacitors that are utilized for quick charging and low-energy demands. In this article, the design of an efficient wireless power transfer system has been presented using resonant inductive coupling technique for supercapacitor-based electric vehicle. Mathematical analysis, simulation, and experimental implementation of the proposed charging system have been carried out. Simulations of various parts of the systems are carried out in two different software, ANSYS MAXWELL and MATLAB. ANSYS MAXWELL has been used to calculate the various parameters for the transmitter and receiver coils such as self-inductance ( L), mutual inductance ( M), coupling coefficient ( K), and magnetic flux magnitude ( B). MATLAB has been utilized to calculate output power and efficiency of the proposed system using the mathematical relationships of these parameters. The experimental setup is made with supercapacitor banks, electric vehicle, wattmeters, controller, and frequency generator to verify the simulation results. The results show that the proposed technique has better power transfer efficiency of more than 75% and higher power transfer density using a smaller coil size with a bigger gap of 4–24 cm.

Comparison of magnetic field distributions generated by various permanent magnets for transcranial static magnetic stimulation: A simulation study

Recent experimental studies have shown that static magnetic field can be effective in modulating human brain functions. Following this discovery, a new noninvasive brain stimulation technique was developed: the transcranial static magnetic stimulation (tSMS). Various types of permanent magnets have been used in previous experimental studies, with the aim of validating the effectiveness of tSMS; nevertheless, the spatial distributions of magnetic field generated by these permanent magnets have not been fully investigated. In this study, we compared the distributions of magnetic field on the human cortical surface generated by five different cylindrical magnets (of various dimensions), using the finite element method. Our simulation results demonstrated that the magnitude of magnetic flux density induced in the cortical grey matter of the human brain is proportional to the volume of permanent magnets used, while the magnetic field gradient is not necessarily proportional to the volume of the magnets. Additionally, we showed that the use of magnets with internal holes might not be advantageous. The differences in magnetic field properties induced by various types of permanent magnets suggested that their careful selection, based on magnetic field simulations, might be necessary to increase the effectiveness of tSMS.

Investigation of magnetorheological brake with rotor of combined magnetic and non-magnetic materials

Magnetorheological (MR) brakes are a type of electromagnetic brakes that make use of controllable viscoelastic properties of magnetorheological fluid for braking. The torque capacity of the MR brake depends on the magnitude of magnetic flux density generated in the MR fluid. In this study, the effect of combination of magnetic and non-magnetic materials for rotor disk of MR brake with the objective to maximizing the flux density in the MR fluid gap at the rotor periphery was investigated. Initially, the MR brake rotor disk radius and MR fluid gap thickness were determined by using Genetic Algorithm optimization technique for desired torque ratio and torque capacity. Magnetostatic analyses were performed at different current magnitudes to determine the magnetic field and flux density in the MR brake. Further, to enhance the magnetic field intensity in the MR fluid at the rotor periphery, the rotor was modeled with three different configurations of MR brake with combinations of magnetic and non-magnetic steel and magnetostatic analyses of the MR brake were performed. It was found that the leakage of flux away from rotor periphery was reduced and there is significant increase and concentration of the magnetic field and flux density in the MR fluid gap through the use of rotor disk with combined magnetic and non-magnetic materials which would subsequently increase the torque capacity of the MR brake.

Performance analysis of planar microcoils for biomedical wireless power transfer links

Planar microcoils are significant components of inductive devices used for biomedical wireless power transfer applications. Biomedical devices implanted inside the human body needs to be powered up at regular intervals which can be done electromagnetically through a planar microcoils’ setup. Different types of planar microcoils such as spiral and non-spiral planar microcoils are compared in this work in terms of their electrical parameters. An analytical model is also developed which is validated using experimental results. The fabrication advantages and low power dissipation of non-spiral coil structures make them a strong alternative for conventional spiral planar coils. Though the magnitude of magnetic flux density is slightly lesser for non-spiral coils, series resistance required for wireless power link is found to be better for the same. The fabrication of non-spiral planar microcoils of various geometries is shown using a single mask level. Coupling factors of various wireless power links are also simulated using different non-spiral planar microcoil geometries to select the optimum geometry for the wireless power link application.

Hand-Held Magnetic Field Meter Based on Colossal Magnetoresistance-B-Scalar Sensor

This paper describes a newly developed hand-held magnetic field meter, which enables the measurement of the magnitude of pulsed, alternating, or permanent magnetic flux density in a range from 0.06 up to 10 T. The device measures the magnitude of magnetic flux density independent of the field direction (B-scalar) and its measurement frequency ranges from dc to 100 kHz. This magnetometer consists of a hand-held magnetic field measurement meter and a pluggable probe whose main element is a spintronic sensor based on the colossal magnetoresistance (CMR) phenomenon. The new design of a probe containing a temperature sensor and a CMR-B-scalar sensor made from two manganite films with different resistivity versus temperature dependences ensures a reduced response signal dependence on temperature and thus increased the accuracy of the measurements. The hand-held meter has a graphical color touch screen for the display of the waveforms and provides measurements without the use of external oscilloscopes or other analog graphing devices. This magnetometer can be used for various industrial and scientific applications such as for the investigation of high-power electrical motors, fast high electrical current transients appearing in cases of the commutation of pulsed power circuits, for the measurement of pulsed magnetic fields in magnetic coils, or for measuring the dynamics of magnetic fields during electromagnetic metal forming and welding.

Prediction of topological Hall effect in a driven magnetic domain wall

We investigate the possible emergence of topological Hall effect (THE) in a driven magnetic domain wall (DW). Numerical simulations based on the Landau–Lifshitz-Gilbert-Slonczewski equation shows that the emergent magnetic flux appears when the DW is in a non-equilibrium state. The magnitude of magnetic flux is modulated by the Dzyaloshinskii–Moriya interaction (DMI), providing an experimental test of the predicted THE by a voltage controlled DMI modulation. These results indicate that the THE can be observed even in a topologically trivial magnetic DW, and therefore open up new possibility to electrically detect the dynamical spin structure.

Alfenol patch-, galfenol patch- and galfenol paint-based torque sensor characterization studies

Alfenol (Fe-Al) and Galfenol (Fe-Ga) are iron-based structural magnetostrictive alloys that, for compositions of ∼81% iron, are increasingly being used in sensing, actuating, and energy harvesting devices [Park et al., AIP Advances 6(5), 056221 (2016)]. Recent improvements in the development of magnetostrictive materials using the deformation processing methods of rolling to produce highly textured thin sheet [Park et al., AIP Advances 6(5), 056221 (2016)] and ball milling to produce (001)-oriented micron-size flakes [S. M. Na, J. Galuardi, and A. B. Flatau, IEEE Transactions on Magnetics 53(11), 1–4 (2017)] provide the opportunity to develop a non-contact torque sensor. Torque-induced shear forces at the surface of a shaft lead to a measurable change in the flux passing through the air above the surface of a shaft to which a magnetostrictive layer has been bonded. The current study builds on prior work which demonstrated that torque influenced the magnitude of magnetic flux in the air gaps located between a piece of Galfenol and the rest of a magnetic circuit [Raghunath et al., Proceedings of the ASME, 2013]. The current work overcomes limitations of the prior work. This work demonstrates that using a magnetostrictive layer made of a patch of Alfenol, an alloy that is less expensive, more ductile, and less magnetostrictive than Galfenol, but has almost the same saturation magnetization of ∼1.5T, slightly outperformed the patches made of Galfenol. Additional contributions of the present work include a first look at the application to a shaft of an epoxy-based paint containing micron-sized flakes of (001)-oriented Galfenol, and a comparison of square and ring-shaped patches (aspect ratios of 1 and of ∼4). Data are presented from quasi-static testing and from dynamic tests at rotational rates of up to 1000 rpm.

Modelling External Magnetic Fields of Magnetite Particles: From Micro- to Macro-Scale

We determine the role of particle shape in the type of magnetic extraction processes used in mining. We use a micromagnetic finite element method (FEM) to analyze the effect of external magnetic fields on the magnetic structures of sub-micron magnetite particles. In non-saturating fields, the magnetite particles contain multiple possible non-uniform magnetization states. The non-uniformity was found to gradually disappear with increasing applied field strength; at 100 mT the domain structure became near uniform; at 300 mT the magnetic structure saturates and the magnetization direction aligned with the field. In magnetic separation techniques, we suggest that 100 mT is the optimal field for magnetite to maximize the magnetic field with the lowest energy transfer; larger particles, i.e., >1 µm, will likely saturate in smaller fields than this. We also examined the effect of external magnetic fields on a much larger irregular particle (L × W × H = 179.5 × 113 × 103 μm) that was too large to be examined using micromagnetics. To do this we used COMSOL. The results show the relative difference between the magnitude of magnetic flux density of the particle and that of a corresponding sphere of the same volume is <5% when the distance to the particle geometry center is more than five times the sphere radius. The ideas developed in this paper have the potential to improve magnetic mineral extraction yield.

Magnetic flux control laws in differential electric drive

This paper considers scheme options of the multimotor differential electric drive system. These schemes have competitive energy and weight-size parameters. The number of independent control commands exceed the number of controlled coordinates. Magnetic flux magnitude of the electric machine may be accepted as a control command. Methods of nonlinear programming synthesized the flux control laws in a multimotor differential electric drive system. The minimum weight-size characteristic of the electric power equipment was taken as an optimization criterion. Possibility of founded control laws approximation was shown by the simple piecewise linear equation. Speed control of the electric drive was changed only by one electric machine flux for each of the segments. Fluxes of other machines remained unchanged, equal to the nominal values. Additional losses did not exceed few percent in case of refusal from the exact control law in the area of small loads. Also, it was not observed in the rated area at all.

Modelling of surface roughness in a new magnetorheological honing process for internal finishing of cylindrical workpieces

A new magnetorheological honing (MRH) process has been developed for internal surface finishing of cylindrical workpieces with different diameters. The process makes use of the tool with radial polarized curved permanent magnet strips and a smart magnetorheological (MR) polishing fluid for finishing the internal surface of the cylindrical workpieces. The MRH tool has the uniqueness that its radial curved permanent magnets can move inwards or outwards just like a honing tool so that the different diametric sizes of the internal surface of the cylindrical components can be finished. In the present work, a mathematical model has been developed for predicting the change in surface roughness while finishing the internal surface of ferromagnetic cylindrical workpieces. An analytical approach is adopted to evaluate the magnitude of magnetic flux density at different points in the working gap where MR polishing fluid is present. While finishing the internal surface of ferromagnetic cylindrical workpieces, a magnetic field is also contributed in the working gap due to the effect of iron particles (present in the MR polishing fluid) and the ferromagnetic cylindrical workpiece. The present developed mathematical model evaluates the magnitude of magnetic flux density in the working gap by also considering the contribution of the magnetic effect of iron particles and the ferromagnetic cylindrical workpiece. Theoretically calculated magnetic flux density distribution in the working gap is validated with the experimentally and also through finite element (FE) analysis using Maxwell Ansoft V13 software. With the evaluated values of magnetic flux density at various points in the working gap, the magnetic normal force exerting over the active silicon carbide (SiC) particle has been evaluated. The computed magnetic normal force exerting over the active SiC particle is utilized to calculate the removal of material in terms of decrease in surface roughness values with various finishing cycles. Also, the developed mathematical model for the present MRH process has been validated by performing the experimentations with same parameters and conditions as selected in modeling for the different number of finishing cycles. Results acquired from the mathematical model are found in close relation to the results obtained from experimentations with the maximum percentage error of 8.06% and least of 1.03%. The developed mathematical model for MRH process can be used to predict the process's finishing performance for various ferromagnetic cylindrical workpieces which can make it useful for industries.

Design, Simulation and Fabrication of a Novel Phage Filter for Pathogens Testing from Large Volumes of Water

In this paper, a phage filter has been developed to capture, concentrate and isolate small numbers of pathogens from large volumes of water. The phage filter consists of a magnetized filter frame and hundreds of phage-coated filter elements made of a magnetoelastic material. ANSYS Maxwell simulations have been conducted on filter designs. Pairs of magnets were used to generate a uniform magnitude of magnetic flux density and a desired direction of flux vectors to align and hold filter elements on the frame. The strip-like filter elements were made of Metglas 2826MB ribbon by mechanically dicing. A prototype filter with high density of filter elements in the size of 2″ has been demonstrated.