Induced Research Articles

Barkhausen Noise‐ and Eddy Current‐Based Measurements for Online Detection of Deformation‐Induced Martensite During Flow Forming of Metastable Austenitic Steel AISI 304L

ABSTRACTThis paper deals with micromagnetic measurements for online detection of strain‐induced α′‐martensite during plastic deformation of metastable austenitic steel AISI 304L. The operating principles of the sensors are magnetic Barkhausen noise (MBN) and eddy currents (EC), which are suitable for detection of microstructure evolution due to formation of ferromagnetic phases. The focus of this study was put on the qualification of different micromagnetic techniques and different measurement systems under conditions similar to the real ones during production, which is crucial for implementation of a property‐controlled flow forming process. The investigation was carried out on tubular specimens produced by flow forming, which have different content of α′‐martensite. To characterize the sensitivity of the sensors, different contact conditions between sensors and workpieces were reproduced. MBN sensors are suitable for detecting amount of α′‐martensite, but the measurements are affected by the surface roughness. This entails that the calibration models for MBN sensors must take account of these effects. EC sensors show a closer match with the amount of α′‐martensite without having major affectation by other effects.

3D numerical simulation of magnetization loss in multifilamentary MgB2wires at 20 K

Abstract High-power density all-superconducting rotating machines have potential for application in electrical aircraft motors.
However, superconductors in the armature windings of such rotating machines carry AC currents under AC/rotating magnetic fields, resulting in AC losses For. reducing AC loss, low-cost, round magnesium diboride (MgB2) wires are one promising material due to their multifilamentary structure, fine filament size and tight twist. To date, previous 3D AC loss simulations have focused on MgB2 wires with a magnetic matrix operating at low frequency and 4.2 K, which are not relevant to aviation applications. In this work, 3D simulations of magnetization loss at 20 K of twisted 2-filament and 54-filament wires with a non-magnetic matrix are carried out using the finite element method, based on the H-formulation, with AC field amplitudes from 0.1 T to 2 T and frequencies up to 200 Hz. The measured Jc(B, 20 K) and n(B, 20 K) data of a non magnetic MgB- 2 wiremanufactured by Hyper Tech Research is assumed as input parameters. For the 2-filament wire, the operational frequency,the twist pitch, the filament size, the matrix resistivity, and inter-filament gap have been varied to systematically study their impacts on magnetization loss and its loss components (hysteresis loss, coupling loss and eddy currents). The simulation results show that the 2-filament wire with a 5 mm twist pitch and a higher resistivity matrix operated at 50 Hz has the lowest magnetization loss through decoupling the filaments. Furthermore, a lower coupling loss at 200 Hz for field amplitudes exceeding 1 T is observed, this is because critical coupling frequency fc shifts to small values with increasing field amplitudes. For the 54-filament MgB2 wire, the magnetization loss of a 5 mm twist pitch and a higher resistivity matrix wire operated at 50 Hz is estimated. The simulations show that the hysteresis loss of the 54-filament wire can be well predicted by the analytical hysteresis loss equation for a cylindrical superconductor multiplied by 54 (the number of filaments) because the filaments are in an uncoupled state. Good agreement is also observed between the simulated coupling loss and the analytical coupling loss equation from Wilson book for a circular-arranged multifilamentary superconducting wire.

Transformer-ultrasonic synchronised rotating sensor for detection of drum shaft defects

ABSTRACT This study presents a novel defect detection system that combines transformer technology with ultrasonic synchronous rotation in drum shafts. Based on electromagnetic induction, a piezoelectric sensor is driven by the transformer’s secondary pulse signal to enable synchronised transmission of both transformer and ultrasonic guided waves as the drum shaft rotates. This integration improves the accuracy and reliability of defect detection. The design process centres on optimising transformer coupling efficiency, ultrasonic guided wave propagation, and synchronisation mechanisms to achieve high-resolution imaging and real-time monitoring in an easy-to-operate system. The results indicate that the system effectively detects defects by analysing echo signals, locating defects through time differences, and functions well within rotating equipment.

Novel Process Approach for Extrusion-Based Metal Wire Additive Manufacturing Using Induction Heating as a Heat Source

A growing number of additive manufacturing (AM) applications use induction heating because of its precision, affordability, safety, and cleanliness. It is widely used in many industrial processes, such as melting, welding, brazing, and preheating. Wire is a considerably more efficient material to use than powder when used as feedstock. Unfortunately, there is still much to learn about the application of induction heating as a heat source in extrusion-based metal additive manufacturing, particularly when wire feedstock is used. This gap was filled by investigating, inhouse developed metal AM system which consists of the combination of induction heating as a heat source and metal wire as a feedstock in additive manufacturing. For this kind of application, induction heating is especially useful since it produces heat inside the workpiece by creating eddy currents. Finite element analysis was initially used to analyze the suitability of extruder material for printing aluminum material. After this investigation, the ability to print aluminum alloy in an extrusion-based metal wire additive manufacturing process with a cast iron extruder has been evaluated through experimentation. Simulation and experimentation results confirm the suitability of cast iron as an extruder material for printing aluminium alloys in a semi-solid state. The tensile test results of wire samples printed through induction heated metal additive manufacturing have been comparable to those of the original wire due to printing the same in a semi-solid state. Though they did not reach the levels attained by wire arc additive manufacturing and casting processes, it was found that the new extrusion-based wire samples showed better elongation and yield strength than the original wire.

Effect of electromagnetic radiations on the dynamics of a five-chain coupled inertial Hopfield neural network and control of multi-stability with the selection of a desired attractor

Abstract In this paper, we investigate the effect of electromagnetic radiation on the dynamics of a network consisting of five chain-coupled inertial Hopfield neurons. The study revealed that the neural system designed such a way involves several complex phenomena, namely Hopf bifurcation, chaos, hyperchaos and the coexistence of up to thirty-two attractors in phase space. The complexity specific to our system is due to the higher number of equilibrium points, namely two hundred and forty-three. Under the conditions of safe functioning of our neural system (chaos or hyperchaos), we have been able to observe that electromagnetic radiation has a harmful character for the system, because we found for a range of variation in the intensity of the electromagnetic feedback induction current a coexistence of chaotic and periodic states (epileptic state). We then controlled the multi-stability using a desired attractor selection scheme, with the aim of suppressing the pathological state. All the work carried out in this contribution is done with the help of dynamical system analysis tools such as the bifurcation diagram, the spectrum and the maximum exponent of Lyapunov, phase portraits and basins of attraction. The scheme used is the Runge-Kutta-4. In order to validate the numerical results, we use analog calculation and some results were derived from the Pspice software. These results are in good accordance in amplitude and location on the plane to those of numerical simulations.

Uncovering soil compaction: performance of electrical and electromagnetic geophysical methods

Abstract. Monitoring soil structure is of paramount importance due to its key role in the critical zone as the foundation of terrestrial life. Variations in the arrangement of soil components significantly influence its hydro-mechanical properties and therefore its impact on the surrounding ecosystem. In this context, soil compaction resulting from inappropriate agricultural practices not only affects soil ecological functions, but also decreases the water-use efficiency of plants by reducing porosity and increasing water loss through superficial runoff and enhanced evaporation. In this study, we compared the ability of electric and electromagnetic geophysical methods, i.e., electrical resistivity tomography (ERT) and frequency-domain electromagnetic (FDEM) method, to assess the effects caused by both heavy plastic soil deformations generated by a super-heavy vehicle and the more common tractor tramlines on silty-loam soils. We then tested correlations between geophysical response and soil variables (i.e., penetration resistance, bulk density, and volumetric water content on collected samples) at different homogeneous areas defined by k-means clustering. This work is intended to be a contribution to clarify expectations about the use of geophysical techniques to rapidly investigate soil compaction at various spatial scales, dissecting their suitability and limitations. It also aims to contribute to the methodological optimization of agrogeophysical acquisitions and data processing in order to obtain accurate soil models through a non-invasive approach. Electrical prospecting has finer spatial resolution and allows a tomographic approach, requiring higher logistic demands and the need for ground galvanic contact. On the other hand, contactless electromagnetic induction methods can be quickly used to define the distribution of electrical conductivity in the shallow subsoil in an easier way. In general, compacted soil portions are imaged as high-electrical-conductivity anomalies relative to the context. Results, validated with traditional soil characterization, show the pros and cons of both techniques and how differences in their spatial resolution heavily influence the ability to characterize compacted areas with good confidence.

Dual-frequency electromagnetic sounding of a Triton ocean from a single flyby.

Triton, the largest satellite of Neptune, is in a retrograde orbit and is likely a captured Kuiper Belt Object (KBO). Triton has a mean density of only 2.061 gm/cm3 and is therefore believed to have a 250-400 km thick hydrosphere. Triton is also one of the few planetary satellites to possess a thick ionosphere whose height-integrated Pedersen conductivity exceeds 104 S, complicating the sounding of Triton's subsurface using electromagnetic induction. Triton experiences a time-varying magnetic field dominated by two periods, one at 14.4 h, at the synodic rotation period of Neptune (from Neptune's tilted field) and one at 141 h, at the orbital period of Triton (from large inclination of Triton's orbit). We show that for most models of ionospheric conductivity, the 14.4 h wave creates a large response from the ionosphere itself and is unable to sound the putative ocean below. However, the 141 h wave penetrates the ionosphere easily and provides information on Triton's ocean. We introduce a technique that allows us to determine the complex magnetic moments generated at the two key periods from the magnetic data from a single flyby, allowing us to infer the presence of a subsurface ocean.This article is part of the theme issue 'Magnetometric remote sensing of Earth and planetary oceans'.

The mechanism of electric field control in the solidification of welding lines in magnesium alloy casting-rolling

According In this paper, two current loading methods are used to improve the solidification welding line of magnesium alloy casting-rolling from "Ɔ" to "1" shape. The results show that the Joule thermal effect can improve the temperature field distribution in the casting-rolling zone after the magnesium alloy melt is energized. Especially in the case of scheme 1, the temperature field distribution in the casting-rolling zone changes obviously. After the electric field is applied, the range of eddy current increases obviously, the accumulation of high temperature metal liquid appears at the eddy current, and the shape of solidification welding line is improved. When the current density is greater than 2.5 e7A /m2, the distance from the bonding point K to the outlet is less than the distance from K "to the outlet. The casting-rolling force on the edge of plate is small, which is conducive to inhibiting the edge crack of magnesium alloy cast-rolled sheet.

Enhancing heat transfer efficiency in solar storage devices using eddy current structures and vibrations

This study introduces a novel phase change material (PCM)-based solar energy storage system integrating Tesla valve-inspired eddy current structures and mechanical vibrations to enhance thermal performance. By systematically optimizing the geometric design and vibration parameters, a 90°shunt angle was identified as the most effective configuration, achieving a significant 59.9% reduction in PCM melting time and completing the melting process in just 178 s. This superior performance was attributed to the generation of strong eddy currents, which disrupted the thermal boundary layer and enhanced heat transfer between the heat transfer fluid (HTF) and PCM. Mechanical vibrations (0.0003 m amplitude and 100 Hz frequency) further improved performance, particularly for shunt angles of 30°and 60°, where melting times were reduced by 13.4% and 13.36%, respectively, demonstrating the synergistic effects of geometry and vibration.The impact of natural convection was evaluated across a range of Rayleigh numbers (11,400 to 1,140,000), revealing that higher Rayleigh numbers enhanced heat transfer, especially for the 90°configuration. In contrast, shunt angles exceeding 90°showed reduced efficiency due to the thickening of boundary layers. Comparative analysis with existing heat transfer enhancement studies demonstrated the superior performance of the proposed system, which achieved greater reductions in melting time compared to designs using fin structures or optimized inclinations. This research provides valuable insights into the development of high-performance, scalable, and sustainable solar energy storage systems, bridging the gap between laboratory innovation and practical application.

A review on magnetic permeability in heat and fluid flow characteristics: Applications in magnetized shielding

Magnetic permeability as a material property has a significant impact on the characteristics of a heated surface where induction heating or magneto-thermal systems are involved. In the heat and fluid flow mechanism where heat induction is used, magnetic permeability has a significant and crucial impact. Materials-like ferromagnetic materials with high magnetic permeability enhance the eddy current formation and can concentrate the magnetic field during the processes. These eddy currents lead to Joule heating in terms of electric current induced within the conductor by a changing magnetic field. Magnetic permeability also impacts the temperature profile within the material. Materials with extraordinary permeability due to the concentration of magnetic field can cause localized heating. The variable material properties in the presence of localized heating lead to non-uniform temperature distribution throughout the medium. In the magnetohydrodynamics heat and fluid flow region in the presence of magnetic permeability, some materials perform magnetostrictive impacts; therefore, they change shape or size under the influence of a magnetic field. The role of magnetic permeability along the heated surface is multifaceted in the system where an electromagnetic field is involved and affects how heat is generated, distributed, and dissipated. It is pertinent to mention that in the system where the electromagnetic field is involved, the magnetic permeability directly impacts the efficiency and uniform heating. Therefore, the understanding and controlling of magnetic permeability is important to design the systems that rely on exact thermal management, such as in magnetic shielding, magneto-thermal devices, and induction heating.

Assessing the Effectiveness of Satellite and UAV-Based Remote Sensing for Delineating Alfalfa Management Zones Under Heterogeneous Rootzone Soil Salinity

Site-specific application of agricultural inputs is crucial for optimizing resource utilization in alfalfa (Medicago sativa L.) production and addressing challenges such as soil salinity. The main objective of this study was to assess the effectiveness of PlanetScope and UAV-based NDVI imagery for delineating alfalfa management zones under heterogeneous rootzone soil salinity. The research was conducted in the alfalfa field located in Imperial Valley, CA. The extent of rootzone soil salinity was assessed using Electromagnetic induction (EMI) technology and deep soil sampling. Reference management zones were then defined using the soil salinity (ECe) map derived from apparent electrical conductivity (ECa) data. Additionally, a time series of NDVI images from PlanetScope imagery and an NDVI image captured using an unmanned aerial vehicle were used to delineate remote sensing-based management zones. Laboratory analysis of disturbed soil samples collected at various depths provided soil physicochemical property data. Soil salinity of the samples ranged from 2.2 to 13.4 dS m−1 with a moderate level of variability (CV = 37.7%). ECe-based management zones accounted for approximately 83% of the field's variability and exhibited substantial differentiation among delineated zones concerning diverse soil properties, including ECa, ECe, gravimetric water content, Mg2+, boron, Ca2+, Na+, and Cl−. Notably, NDVI images effectively captured field variability on par with ECe-based zoning. Moreover, NDVI images recommended the same optimal number of zones (i.e., three) to address the field's variability, aligning with the ECe-based zoning approach. Our findings highlight that heterogeneity of soil salinity in the root zone primarily impacts the variability of alfalfa NDVI early in the growing season. Consequently, this early stage emerges as the most opportune timeframe for NDVI-based zoning for rapid assessment of rootzone soil salinity concerns.

Homogenization Technique of Nanocrystalline Cores Considering the Inter-Laminar Eddy Currents Due to Inter-Layer Contact

Homogenization Technique of Nanocrystalline Cores Considering the Inter-Laminar Eddy Currents Due to Inter-Layer Contact

In vivo reduction of biofilm seeded on orthopaedic implants.

Electromagnetic induction heating has demonstrated in vitro antibacterial efficacy over biofilms on metallic biomaterials, although no in vivo studies have been published. Assessment of side effects, including thermal necrosis of adjacent tissue, would determine transferability into clinical practice. Our goal was to assess bone necrosis and antibacterial efficacy of induction heating on biofilm-infected implants in an in vivo setting. Titanium-aluminium-vanadium (Ti6Al4V) screws were implanted in medial condyle of New Zealand giant rabbit knee. Study intervention consisted of induction heating of the screw head up to 70°C for 3.5 minutes after implantation using a portable device. Both knees were implanted, and induction heating was applied unilaterally keeping contralateral knee as paired control. Sterile screws were implanted in six rabbits, while the other six received screws coated with Staphylococcus aureus biofilm. Sacrifice and sample collection were performed 24, 48, or 96 hours postoperatively. Retrieved screws were sonicated, and adhered bacteria were estimated via drop-plate. Width of bone necrosis in retrieved femora was assessed through microscopic examination. Analysis was performed using non-parametric tests with significance fixed at p ≤ 0.05. The width of necrosis margin in induction heating-treated knees ranged from 0 to 650 μm in the sterile-screw group, and 0 to 517 μm in the biofilm-infected group. No significant differences were found between paired knees. In rabbits implanted with sterile screws, no bacteria were detected. In rabbits implanted with infected screws, a significant bacterial load reduction with median 0.75 Log10 colony-forming units/ml was observed (p = 0.016). Induction heating was not associated with any demonstrable thermal bone necrosis in our rabbit knee model, and might reduce bacterial load in S. aureus biofilms on Ti6Al4V implants.

Research and design of transient test platform for DC current transformer

This article studies the design and simulation of a transient test platform for DC current transformers to verify the effectiveness of the design scheme. DC current transformers convert large currents on the primary side into small currents on the secondary side through electromagnetic induction principles and are widely used in power systems. In order to verify the feasibility of the design scheme, simulation research was adopted, and the simulation parameters were the same as the actual scheme, including controllable current source parameters, cable parameters, and MOS switch branches. The simulation results show that the designed DC transient square wave current source can effectively compensate for the impulse current, and the output current waveform is stable, meeting the design requirements.

Evaluation of MRI safety of Ru-106 Eye applicators

Introduction: Ruthenium-106 brachytherapy is a primary treatment for Uveal Melanoma (UM), the most common intraocular malignancy in adults. This study evaluated the safety of Ru-106 applicators at 3 Tesla (T) MRI and their impact on image quality. Methods: Magnetic attraction and eddy currents were tested on a 20mm diameter Ru-106 applicator using a nylon string and a porcine eye. Safety criteria were defined by ocular oncologists, comparing magnetic field interactions to the forces exerted on the eye during surgery. Five UM patients were scanned at 3T MRI with the applicator in-situ using both conventional anatomical sequences and scans optimized to reduce metal artifacts. Results: Minimal magnetic interactions was observed. Eddy currents caused slight lagging during fast movements, and temporary detachment of the applicator of the porcine eye in conditions that were considered unrealistic for clinical scans. Significant susceptibility artifacts compromised image quality of the affected eye. Conclusion: Patients with Ru-106 applicators can be safely used in 3T MRI with some simple precautions. MR-image quality of the eye was poor due to major susceptibility artefacts, however, imaging of extra-ocular anatomy is feasible.

A Thermal Cycler Based on Magnetic Induction Heating and Anti-Freezing Water Cooling for Rapid PCR

Distinguished by its exceptional sensitivity and specificity, Polymerase Chain Reaction (PCR) is a pivotal technology for pathogen detection. However, traditional PCR instruments that employ thermoelectric cooling (TEC) are often constrained by cost, efficiency, and performance variability resulting from the fluctuations in ambient temperature. Here, we present a thermal cycler that utilizes electromagnetic induction heating at 50 kHz and anti-freezing water cooling with a velocity of 0.06 m/s to facilitate rapid heating and cooling of the PCR reaction chamber, significantly enhancing heat transfer efficiency. A multi-physics theoretical heat transfer model, developed using the digital twin approach, enables precise temperature control through advanced algorithms. Experimental results reveal average heating and cooling rates of 14.92 °C/s and 13.39 °C/s, respectively, significantly exceeding those of conventional methods. Compared to commercial PCR instruments, the proposed system further optimizes cost, efficiency, and practicality. Finally, PCR experiments were successfully performed using cDNA (Hepatitis B virus) at various concentrations.

Dynamics and implementation of a functional neuron model with hyperchaotic behavior under electromagnetic radiation

Prolonged exposure to electromagnetic radiation (EMR) may be hazardous to human health and plays a key role in the medical diagnosis of some diseases. And this effect can be better demonstrated by constructing a neuron model of EMR. Flux-controlled memristors can estimate the effects of EMR on neurons. In this work, a discrete flux-controlled memristor is used to estimate the behavior of EMR. Furthermore, the memristor is introduced into a neuron model to explore the effects of EMR on the behavior of neurons. The rich and interesting complex dynamical behavior of the model is investigated using analytical methods from nonlinear theory, including plotting bifurcation diagrams, Lyapunov exponent spectra (LEs) and complexity. By modulating the electromagnetic induction strength k of the memristor, it was observed that the introduction of EMR is able to generate hidden hyperchaotic attractors and initial-boosted behavior. The constructed neuron model is implemented based on a DSP platform. Pseudo random number generators (PRNGs) are further designed and the NIST test results illustrate the excellent random performance of the sequences generated by the neuron model. The properties exhibited in the neuron model under EMR provide a reference solution for EMR in the diagnosis and treatment of certain diseases.

Research on comprehensive heat dissipation characteristics of AlSi7Mg TPMS heat sinks manufactured by laser powder bed fusion

The comprehensive heat transfer characteristics of triply periodic minimal surface heat sinks were investigated in this research, and triply periodic minimal surface structures were manufactured by laser powder bed fusion with AlSi7Mg powder. The average surface temperature, thermal resistance, heat transfer coefficient, and specific heat transfer coefficient of heat sinks were tested, and the heat dissipation mechanism was analyzed by finite element thermal flow analysis. The results of thehomogeneous triply periodic minimal surface show that Primitive has the best comprehensive heat transfer performance under forced convection, and Gyroid is the best without forced convection. Compared with homogeneous and gradient triply periodic minimal surfaces, the P-Quadratic ΙΙ structure has the best comprehensive heat transfer performance under forced convection and natural thermal conductivity. Compared with homogeneous Primitive, the average convection heat transfer coefficient of P-Quadratic ΙΙ is increased by 13.44 % ∼ 19.78 %. The finite element thermal flow analysis shows that the narrow tube effect of Bernoulli’s principle and eddy current enhanced the heat transfer performance of Primitive and gradient Primitive.

Bioinspired Magnetized String with Tension-Dependent Eigenfrequencies for Wearable Human-Machine Interactions.

Flexible and wearable devices have exhibited potential for applications in the fields of human-machine interactions (HMIs) and Internet of Things. However, challenges remain in the improvement of the communication storage capacity with a simplified architecture. Inspired by tension regulation in natural tendons, a single-channel wearable HMI strategy is proposed using the eigenfrequency of magnetized strings as a sensing solution. Based on electromagnetic induction, mechanical vibration of the magnetized string can electrically induce periodical damping signals in the coil that are associated with the intrinsic eigenfrequency property of the string. Using a theoretical vibration model, nonoverlapping eigenfrequencies are precisely customized by designing the dimension/modulus or tension status of the string to broaden the eigenfrequency library. By integrating strings with different eigenfrequencies, multiple commands can be realized with a single communication channel. Moreover, identifiable commands can be flexibly tuned with only one magnetized string by customizing the tensile length (string tension) for eigenfrequency regulation. Demonstrations such as tactile addressing, authentication systems, and robotic control indicate the potential of the interface for multifunctional HMI applications. We expect that this strategy will provide a valuable reference for the future design of wearable HMI interfaces with high storage capacity and controllability in an accessible architecture.

Electromagnetic induction imaging with a SERF atomic magnetometer

We construct an electromagnetic induction imaging (EMI) system based on a SERF (Spin-Exchange-Relaxation-Free) atomic magnetometer. The homemade SERF magnetometer relies on the optical magnetic resonance absorption to obtain the magnitude of the secondary magnetic fields of object, and only one laser beam is used for both pumping and detection. Besides, by using sub-harmonics in beating signal, the scheme of the imaging system is simplified with fast Fourier transform (FFT) instead of the lock-in amplifier. Overall, our scheme has a simple structure, which is very conducive to miniaturization and portability. In our experiment, the frequency regions of RF and the corresponding magnitude of the generational secondary magnetic field are both investigated to find that the optimal operation RF frequency is about kHz, which lead to a deeper object’s penetration depth. Furthermore, due to the high sensitivity of SERF atomic magnetometer, we can have a clear imaging based solely on the magnitude of the secondary magnetic fields without the information of its phase.