Magnetic Array Research Articles

An Advanced Hall Element Array-Based Device for High-Resolution Magnetic Field Mapping.

The precise mapping of magnetic fields emitted by various objects holds critical importance in the fabrication of industrial products. To meet this requirement, this study introduces an advanced magnetic detection device boasting high spatial resolution. The device's sensor, an array comprising 256 unpackaged gallium arsenide (GaAs) Hall elements arranged in a 16 × 16 matrix, spans an effective area of 19.2 mm × 19.2 mm. The design maintains a 1.2 mm separation between adjacent elements. For enhanced resolution, the probe scans the sample via a motorized rail system capable of executing specialized movement patterns. A support structure incorporated into the probe minimizes the measurement distance to below 0.5 mm, thereby amplifying the magnetic signal and mitigating errors from nonparallel probe-sample alignment. The accompanying interactive software utilizes cubic spline interpolation to transform magnetic readings into detailed two- and three-dimensional magnetic field distribution maps, signifying field strength and polarity through variations in color intensity and amplitude sign. The device's efficacy in accurately mapping surface magnetic field distributions of magnetic and magnetized materials was corroborated through tests on three distinct samples: a neodymium-iron-boron magnet, the circular magnetic array from a smartphone, and a magnetized 430 steel plate. These tests, focused on imaging quality and magnetic field characterization, underscore the device's proficiency in nondestructive magnetic field analysis.

A piezoelectric and electromagnetic hybrid energy harvester based on two-stage magnetic coupling

Traditional piezoelectric energy harvesters cannot adapt to environmental energy with low frequency, wideband, and randomness because of the narrow working bandwidth. The introduction of magnetic coupling can improve the narrow-band characteristics of piezoelectric energy harvesting structures. To explore more efficient broadband methods, this paper designs a piezoelectric and electromagnetic hybrid energy harvester (PEEH) based on two-stage magnetic coupling to realize the expansion of piezoelectric energy harvesting bandwidth. In this paper, the magnetic pole alternating frequency is changed and the output of the structure is tested, and the operating frequency bands under different alternating frequencies are compared according to the test results. It can be seen from the experimental results that the output performance of the structure is obviously improved by increasing the AC frequency of the magnetic pole while reducing the optimal frequency point of the structure. When the number of magnets in the rotor magnet array is 6, increasing the pole alternating frequency can effectively improve the output performance of the electromagnetic unit when the rotor speed is low, and can also increase the maximum output voltage and energy harvest bandwidth of the piezoelectric unit by 189% and 150%, respectively. Therefore, by increasing the alternating frequency of magnetic poles, the output voltage of the structure can be improved, and the bandwidth of the structure can be broadened.

Dynamics and capability of along orbit debris self-collecting with rotating constant magnets

Orbital debris with equivalent size of 1∼10 cm is hard to be detected and its number is huge, which is the most harmful to on-orbit spacecraft while there is still no effective removal means. Inspired by vacuum cleaner, applying the conductive property of orbital debris and the physical law that variable magnetic flux would induce eddy current on the surface of a conductive material, this paper put forward a novel approach of ‘along orbit debris self-collecting with rotating constant magnetic dipole array’. Based on dynamic modeling, self-collecting feasibility and control capability analysis, evolution law of relative orbital motion with induced magnetic force derivation, and on-orbit debris magnetic collecting numerical simulation, this novel approach has been verified and the corresponding requirements of magnetic collector are put forward. In addition, this paper also gave how to use several key parameters to adjust the region of along orbit debris self-collecting, and pointed out several problems needing to be researched in-depth for actual application.

Exploring physical and digital architectures in magnetic nanoring array reservoir computers

Physical reservoir computing (RC) is a machine learning technique that is ideal for processing of time dependent data series. It is also uniquely well-aligned to in materio computing realisations that allow the inherent memory and non-linear responses of functional materials to be directly exploited for computation. We have previously shown that square arrays of interconnected magnetic nanorings are attractive candidates for in materio RC, and experimentally demonstrated their strong performance in a range of benchmark tasks (Dawidek et al 2021 Adv. Funct. Mater. 31 2008389, Vidamour et al 2022 Nanotechnology 33 485203, Vidamour et al 2023 Commun. Phys. 6 230). Here, we extend these studies to other lattice arrangements of rings, including trigonal and Kagome grids, to explore how these affect both the magnetic behaviours of the arrays, and their computational properties. We show that while lattice geometry substantially affects the microstate behaviour of the arrays, these differences manifest less profoundly when averaging magnetic behaviour across the arrays. Consequently the computational properties (as measured using task agnostic metrics) of devices with a single electrical readout are found to be only subtly different, with the approach used to time-multiplex data into and out of the arrays having a stronger effect on properties than the lattice geometry. However, we also find that hybrid reservoirs that combine the outputs from arrays with different lattice geometries show enhanced computational properties compared to any single array.

Solving inverse problems in magnetic field leakage sensor array inspection of petroleum tank floor

The MFL method is a qualitative inspection tool and is a reliable, fast, and economical nondestructive testing method for tank floors. In this paper, before presenting the defect reconstruction procedure, we studied the effect of defect parameters on the magnetic field leakage measured by a single Hall sensor. As predicted, the study of each parameter has demonstrated that any variation in the geometrical parameters of the studied defect induce a significant influence on the MFL signal amplitude and distribution; for this reason, all the defect parameters must be determined precisely and prudently. After that, we have studied the performance of defect shape reconstruction from MFL array sensor imaging and depth estimation while using an iterative inversion method. Indeed, the first stage consists of determining the defect width and length from magnetic flux leakage mapping reconstructed from the recorded signals of the micro-integrated magnetic sensors. As a second step, after coupling Comsol and Matlab software, the defect depth is obtained by coupling the 3D finite elements method and a fast iterative algorithm recently developed. Consequently, the defect shape and size are obtained after a few iterations with a relative error of less than 2%; which makes this method very appropriate for real-time defect reconstruction and quantification. Furthermore, this method of defect reconstruction and seizing can be extended for irregular shape such as cracks and corrosion. In fact, this can be done while subdividing the affected area of non-constant depth into elementary zones of a constant depths. Then, while modifying the previous algorithm, we determine the corresponding depth of each zone.

Smart nodding duck: A hybrid Halbach electromagnetic piezoelectric self-powered sensor for smart fisheries

Wave energy harvesting plays a crucial part in promoting the sustainable development of marine fisheries. This paper presents a novel hybrid electromagnetic and piezoelectric Self-powered Sensor, known as the Smart Nodding Duck (SND). The SND consists primarily of two components: an electromagnetic generator (EMG) responsible for power generation and a piezoelectric generator (PEG) dedicated to monitoring purposes. The SND absorbs wave energy through the shell of the nodding duck, while the planetary wheel system forms a coaxial counter-rotating augmentation structure. Also, the Halbach magnetic array serves as the electromagnetic generator, simultaneously exciting the piezoelectric structure to generate voltage signals. These features enable the SND to contribute to the LSTM network modeling self-sensing system, facilitating the monitoring of sea states. To verify the power generation effect of the SND, we conducted bench tests. The results demonstrate that the electromagnetic generator achieves an average output power of 96.26mW under a wave excitation of 0.8 Hz with an amplitude of 80 mm, yielding a power density of 16 W/m3. Furthermore, the self-sensing sea state monitoring model exhibits an impressive accuracy of 99.3 %. Moreover, tank experiment verified the feasibility of the SND, further contributing to the construction of a smart marine fishery Internet of Things.

A neural network inverse problem solution for a MIMO magnetic levitation actuator

A multiple-input and multiple-output planar actuator is proposed, which utilizes mechanically driven stator magnet arrays to levitate a permanent magnet mover. A state of levitation and actuation is obtained by mechanically altering the orientation of the stator magnets to control the forces and torques on the mover. A challenge for the design and control of the actuator is inverting the relationship between the force and stator magnet rotation angles, as there is no closed-form analytical solution. In this study, a feed-forward neural network is applied to model the forward relation between stator magnet angle input and a force and torque output to reduce the forward computation time for the design process and for error estimation in real-time applications. Additionally, the neural network is considered for inverting the solution for a motion profile sampled at 1000 Hz. The developed forward model is able to calculate the forces and torques on the mover a factor 10 faster than the equivalent charge or Fourier model with an absolute error of 3 mN and 0.1 mNm for the forces and torques, respectively, and a feed-forward neural network is able to accurately learn an inverse solution for small motion profiles.

A Rapid Localization Method Based on Super Resolution Magnetic Array Information for Unknown Number Magnetic Sources.

A rapid method that uses super-resolution magnetic array data is proposed to localize an unknown number of magnets in a magnetic array. A magnetic data super-resolution (SR) neural network was developed to improve the resolution of a magnetic sensor array. The approximate 3D positions of multiple targets were then obtained based on the normalized source strength (NSS) and magnetic gradient tensor (MGT) inversion. Finally, refined inversion of the position and magnetic moment was performed using a trust region reflective algorithm (TRR). The effectiveness of the proposed method was examined using experimental field data collected from a magnetic sensor array. The experimental results showed that all the targets were successfully captured in multiple trials with three to five targets with an average positioning error of less than 3 mm and an average time of less than 300 ms.

A Lorentz force-based SH-typed electromagnetic acoustic transducer using flexible circumferential printed circuit

Structural health monitoring (SHM) of in-service structures is becoming increasingly important. The fundamental shear horizontal (SH0) guided wave mode in plate-like structures shows great potential in damage detection due to its non-dispersive and in-plane vibration properties. In order to generate SH0 waves, a practical Lorentz force-based electromagnetic acoustic transducer (EMAT) was introduced in this study using the flexible circumferential printed circuit (CPC). The designed principle of CPC-EMAT was similar to that of the circumferential magnet array (CMA)-based EMAT. However, the structure of the CMA-EMAT is complex, and it is difficult to assemble for generating high frequency and uniformly distributed omnidirectional SH0 waves. Firstly, the performance of the CMA-EMAT with different numbers of magnets was investigated by finite element simulations. Then, the CPC was proposed to replace the CMA with an optimized designed on its size. The CPC-EMAT is easier to fabricate compared to the CMA-EMAT. Finally, experimental tests were conducted for systematic validations on the transducer properties. Simulation and experimental results show that the CPC-EMAT can successfully generate the desirable and acceptable omnidirectional SH0 waves. The proposed CPC-EMAT is anticipated to find widespread application in SH-typed guided wave-based SHM.

Measurement-driven neural-network training for integrated magnetic tunnel junction arrays

Measurement-driven neural-network training for integrated magnetic tunnel junction arrays

Electromagnetic vibrational energy harvester with targeted frequency-tuning capability based on magnetic levitation

Electromagnetic vibrational energy harvester with targeted frequency-tuning capability based on magnetic levitation

Evaluation of stress-loaded ferromagnetic structures using the magnetic recording method and extended signal analysis

This paper presents a new method of analysis of results obtained using the Magnetic Recording Method (MRM), which was applied to inspect tensile stress-loaded ferromagnetic samples. The MRM method comprised a two-step procedure. In the first step, a strictly defined magnetic pattern is recorded on the samples using an array of permanent magnets, and then the original residual magnetization is measured. Next, the samples are subjected to static stress. In the second step, the residual magnetization measurement is repeated. Comparative analysis of the measurement results allows for an accurate and unambiguous assessment of applied stress in steel components. Moreover, the magnetization was measured again after three years to investigate the effect of time on magnetization patterns. The study confirms that the method is stable and has a negligible time dependence.

Calculation of the parameters of an axial flux motor as an actuator of automotive systems

Problem. Axial flux electric motors offer several significant advantages compared to electric motors of traditional design. Currently, scientific periodicals contain numerous publications regarding the development and use of axial flux electric motors with printed windings across various fields. These include applications such as HDD-drives in computer technology, fans and pumps of various capacities, propulsion systems for bicycles and motorcycles, including in-wheel motors, manipulator drives for machine tools and industrial robots, and even within space technologies. Research confirms the high efficiency and size-to-weight ratios of axial flux motors when modern technologies are employed. However, there is little information available regarding the application of such motors in automotive electromechanical equipment. A distinctive feature of automotive electrical systems is their predominantly 12 V onboard power supply, along with high demands on size-to-weight ratios and reliability in conditions of elevated vibrations and wide temperature ranges. In this context, the development of an axial flux motor for automotive applications becomes relevant, particularly as an actuating mechanism for auxiliary systems such as window lifters, windshield wipers, air conditioning, and cooling fans, etc. Goal. The goal of the article is to determine the feasibility of using an axial flux electric motor as an actuator for automotive auxiliary systems by comparing its calculated parameters with the parameters of motors of traditional design using modern technologies and materials. Methodology. The methods and algorithms used for the calculation of electric machines take into account the characteristics and physical processes specific to axial flux machines with printed windings and permanent magnet arrays. Results. A comparison of the obtained characteristics of the designed motor with the characteristics of a modern prototype of traditional design was conducted. Based on the comparison, it was determined that the designed motor has better size-to-weight ratios while maintaining energy performance. Consequently, a conclusion was drawn about the feasibility of using electric motors with axial flux as actuators for automotive auxiliary systems. Originality. The prototype of the designed motor is considered to be a 250 W DC motor with a supply voltage of 12 V. The imposed constraint on the external diameter of the designed motor is set to 100 mm. Practical value. At the same output power and nearly identical torque, the calculated motor exhibits higher size-to-weight ratios. The weight of the calculated motor is 46% of the weight of the prototype. With an external diameter 54% larger than the prototype, the axial length of the calculated motor is 73% smaller. The mass of the calculated motor is 2.34 times smaller than the mass of the prototype.

Weft insertion guideway design based on high-temperature superconducting levitation

Abstract Wide-width weaving machines typically employ the method of increasing the shuttle’s initial speed to achieve a broader weft insertion. However, this approach not only leads to issues such as significant equipment vibrations, high noise levels, increased energy consumption, and reduced lifespan but also has limitations in achieving substantial increases in the fabric width. The article proposes a wide-width weft insertion method based on high-temperature superconducting magnetic levitation technology. It utilizes the levitation characteristics of high-temperature superconducting shuttles in a permanent magnet array’s magnetic field to levitate the shuttle. The shuttle is then propelled by a traveling wave magnetic field generated by an array of electromagnetic coils, enabling wide-width weft insertion. Based on the required thrust values and weaving speed for the shuttle insertion process, the structural parameters of the weft insertion guideway were calculated. A superconducting suspended weft insertion structure was designed, and a mathematical model between the weft insertion guideway and the shuttle was established. Subsequently, a simulation model of the weft insertion guideway was created using Simulink, and the model was simulated, verified, and analyzed using the field-oriented control algorithm. The simulation results indicate that the operating speed of the levitated shuttle and the driving force for weft insertion meet the requirements for high-speed wide-width weaving.

Mixed convection by buoyancy and magnetothermal forces

The magnetic force in the paramagnetic fluid depends on the local gradient of magnetic flux density and the temperature-dependent magnetic susceptibility. In the presence of the gravity, the buoyant force due to the temperature difference additionally overlaps, and the resultant flow becomes a mixed convection. In this study, the effect of the temperature-dependent magnetic force (magnetothermal force) on the natural convection was numerically investigated. The magnetic field formed by the permanent-magnet array was employed and effective one was discussed in terms of the heat transfer. A three-dimensional Rayleigh-Benard convection simulation was conducted with the magnet array below the bottom hot wall. It was found that the magnetothermal force enhances the convection not only where the magnet locates but also away from the magnet due to the force profile.

Improving the homogeneity of Halbach arrays by optimizing magnet combinations using a genetic algorithm.

The purpose of this study was to test the effectiveness of using a genetic algorithm to find the optimal combination of permutations of permanent magnets in a Halbach magnet array in order to achieve the best magnetic field homogeneity in this work area. The test took place on a simple Halbach magnet array of 32 cubic permanent magnets. The magnetization of these magnets was preliminary assessed. Our calculations demonstrate that it is possible to achieve homogeneity of the magnetic field within the working area comparable to that of ideal identical magnetic blocks. Therefore, our study shows that combinatorics can be used to optimize homogeneity without selecting magnetic blocks, which can significantly reduce the cost of manufacturing the final structure.

Signal Processing Using a Circular Sensor Array to Measure the Torsional Angle of a Bolted Joint.

This study presents a new approach to determining the preload force of bolted joints. The concept involves measuring the torsional angle without contact. For this purpose, we present a circular magnetic sensor array integrated into the torque wrench. The torsional angle in bolted joints depends on the dimensions of the screw and the materials used and is typically less than four degrees. For this reason, one requirement is a high angular resolution so that a continuous recording of the torsion angle is feasible during the assembly process. This can be achieved using the circular sensor array and adapted signal processing methods. Two signal processing approaches are utilized. First, the direct method uses the discrete Fourier transformation to calculate the rotation angle from the signal phase. This approach is robust to signal distortion and does not depend on signal amplitude. Second, the method with a learning phase employs Gaussian process regression to minimize the angle error. In an experiment, both approaches were applied within a test bench and showed promising results. The direct method demonstrated a very good angular resolution without training and calibration. For mobile and less-complex applications where a reference system is unavailable, the direct method is preferable. However, in complex measurement systems where reference systems can be utilized initially, significant enhancements to an excellent resolution can be achieved through prior training.

A Concentrically Moveable Erosion Zone Magnetron for In Operando Tailoring of Alloy Nanoparticles in a Gas Aggregation Source

AbstractOne particularly interesting approach for the deposition of highly pure nanoparticles (NPs) in a solvent‐ and surfactant‐free process is the gas phase synthesis of nanoparticles using a gas aggregation source (GAS) based on magnetron sputtering. Apart from the possibility of tuning the NP size‐distribution via process parameters, e.g., gas flow, pressure, and aggregation length, multicomponent targets in a GAS enable in operando composition tuning of alloy NPs. However, in the practical application of the GAS, two main challenges have to be addressed: low target utilization and low conversion efficiency. This work describes a magnetron with a concentrically moveable erosion zone (cMEZ magnetron), and showcases its applicability for the deposition of metal (Cu) and metal alloy (CuNi) NPs via GAS. The cMEZ magnetron relies on an in operando reconfigurable outer magnet array, which enables tuning of the position of the erosion zone, impacting target utilization. By weighting the targets and substrates before and after deposition, the conversion efficiency is determined for different operating pressures and magnet configurations. Furthermore, the multicomponent target approach is tested with the cMEZ magnetron, which enabled the in operando composition tuning of the Ni content in CuNi NPs from ≈5 to ≈35 at% only by varying the magnetic field.

A CGLS-based method for solving magnetic moments of hybrid-model magnetic targets

In order to solve the problem of magnetic moment estimation of magnetic targets, the inverse problem of magnetic moment estimation was constructed based on the hybrid model of ellipsoid and magnetic dipole array. In order to solve the ill-posed problem of the magnetic moment estimation equations, the method was designed to estimate the magnetic moment parameters of the ellipsoid and magnetic dipole array, and the improved discrepancy principle and the maximum chi-square distribution stop criterion were introduced to improve the semi-convergence behavior of the conjugate gradient least squares (CGLS) method. Through simulation examples of magnetic target magnetic moment estimation and ship model measurement data, the performance of two CGLS methods, Tikhonov algorithm and stepwise regression method, were compared and analyzed from four aspects: relative error of magnetic moment estimation, relative error of magnetic field fitting, relative error of magnetic field extrapolation, and computational time complexity. The CGLS method has the advantages of high accuracy of magnetic moment estimation, high immunity of magnetic moment estimation to interference, high accuracy of magnetic field fitting and extrapolation, and low computational time complexity.

Insight of Jeffrey flow over a stretching Riga plate with activation energy and viscous dissipation: Melting heat transfer regime

AbstractPresent article highlights the significance of Arrhenius activation energy along with viscous dissipation in Jeffrey fluid over a Riga plate. Riga plate is basically an actuator made up of array of magnets and electrodes scaled on a plane surface to tackle the weaker electrical conductivity during fluid flow. In order to ensure the novelty, a reliable melting heat surface condition has been incorporated on nonlinear stretching Riga plate of variable thickness to reconnoiter features of heat transfer. Moreover, stagnation point has been retained in this study. Adequate transformations are employed in order to attain system of nonlinear ordinary differential equations. A well known semi analytical technique (Homotopy analysis method) is utilized to obtain series solutions of prevailing dimensionless equations. Influence of several apposite parameters on velocity, thermal and concentration distributions is analyzed graphically. Physical evaluation and graphical sketch is presented for drag force coefficient and rate of heat transfer. Analysis of velocity as well as associated boundary layer thickness gives the growing up impact for the strength of modified Hartmann number. Enhancement of dimensionless reaction rate and endothermic/exothermic reaction parameter results in increment for heat flux over stretching Riga plate. Increase in thermal distribution takes place for higher Eckert number while thermal boundary layer thickness depicts opposite trend in this case. Concentration boundary layer thickness enhances while concentration profile declines for higher Schmidt number. Velocity distribution is found to be incremented for intense melting process. Higher dimensionless activation energy parameter is analyzed to be responsible for growing up concentration field.