Induced Research Articles

Electromagnetic Nanocoils Based on InGaN Nanorings

Energy issues, including energy generation, conversion, transmission and detection, are fundamental factors in all systems. In micro- and nanosystems, dealing with these energy issues requires novel nanostructures and precise technology. However, both concept and setup are not well established yet in the microsystems, especially for those at the nanometer scale. Here, we demonstrate electromagnetic nanocoils with 100 nm diameters based on uniform and periodic InGaN nanoring arrays grown on patterned GaN surfaces using nanoscale selective area epitaxy (NSAE). We observed stronger photoluminescence from the periodic InGaN nanoring arrays compared to the non-uniform InGaN nanorings, which indicates good crystal quality of the InGaN nanostructure with the NSAE. Based on this kind of nanostructure, electromagnetic induction from the nanorings is detected through the rebound movement of high-energy electron diffraction patterns that are influenced by a modulated external magnetic field. Our results clearly show the generation of an inductive current and internal magnetic field in the nanorings. We anticipate this kind of nanostructure to be a potential key element for energy conversion, transfer and detection in nanosystems. For example, it could be used to fabricate microtransformers and micro- and nanosensors for electromagnetic signals.

Effect of a Crack on the Displacement Current Field of Non–electrically Conductive Materials via Electromagnetic Induction Testing

Effect of a Crack on the Displacement Current Field of Non–electrically Conductive Materials via Electromagnetic Induction Testing

FOOTSTEP POWER GENERATOR

The growing need for sustainable and renewable energy sources is driven by environmental issues and energy shortages. The footstep power generator is a groundbreaking energy harvesting system that transforms the mechanical energy produced by human footsteps into electrical energy. This paper examines different methodologies, operational principles, and applications of footstep power generation. It also explores the benefits, challenges, and future potential of this technology. Key Words: Footstep power generation, renewable energy, piezoelectric energy, electromagnetic induction, sustainable technology, smart cities, IoT, smart sensors.

Complex dynamics in chain HNN with parameter-relied equilibria and memristive electromagnetic induction.

Investigating the dynamics of neural networks under electromagnetic induction contributes to understanding the complex electrical activity in the brain. This paper proposes a memristive chain Hopfield neural network (MCHNN) containing unidirectional synaptic connections, where a flux-controlled memristor mimics the electromagnetic induction between neurons. Under different parameters, the equilibria of MCHNN have different numbers and properties, thus producing diverse dynamics. Numerical analysis shows that there are diverse coexisting attractors, such as point attractors and periodic and chaotic attractors, which are yielded from different initial conditions. Moreover, the memristor's internal parameter can be considered as a special signal controller. It acts on the oscillation amplitude of the neuron's output signal, along with amplitude control and offset-boosting about the flux. By building a feasible hardware platform, the numerical analysis outcomes are supported, and the existence of the proposed MCHNN is verified. In addition, the NIST test outcomes indicate that MCHNN has good pseudo-randomness and is suitable for engineering applications.

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

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

A novel physical vapor deposition setup applying high-frequency currents: Deposition of Cu thin films

A novel physical vapor deposition setup applying high-frequency currents: Deposition of Cu thin films

Anisotropic resistivity estimation and uncertainty quantification from borehole triaxial electromagnetic induction measurements: Gradient-based inversion and physics-informed neural network

Anisotropic resistivity estimation and uncertainty quantification from borehole triaxial electromagnetic induction measurements: Gradient-based inversion and physics-informed neural network

2D boron nitride synthesis via electromagnetic induction heating: Experiments and thermochemical modeling

2D boron nitride synthesis via electromagnetic induction heating: Experiments and thermochemical modeling

Numerical investigation of the velocity field around the spur dike in 90° bend

This study simulated the velocity field in a 90° bend with the spur dike using Computational Fluid Dynamics (CFD) and Artificial Neural Network (ANN). The Model results were compared with the physical model data. The Computational Fluid Dynamics model used governing equations for incompressible viscous fluid motion in the turbulent state. The ANN model used Cartesian coordinate system components as input variables and velocity values as output variables. The results showed that both models could successfully identify the eddy currents around the spur dike, the velocity variations through the channel, the accuracy of the estimating model was assessed by computing the correlation coefficient. The results of the error evaluation criteria, including correlation coefficient (R2), Mean Absolute Percentage Error (MAPE) and Scatter Index (SI) are equal to 0.79, 30.7 and 0.05 for the CFD model and 0.97, 6.1 and 0.02 for the ANN model respectively.

Revisiting the safety limit in magnetic nanoparticle hyperthermia: insights from eddy current induced heating

Objective.Magnetic nanoparticle hyperthermia (MNH) emerges as a promising therapeutic strategy for cancer treatment, leveraging alternating magnetic fields (AMFs) to induce localized heating through magnetic nanoparticles. However, the interaction of AMFs with biological tissues leads to non-specific heating caused by eddy currents, triggering thermoregulatory responses and complex thermal gradients throughout the body of the patient. While previous studies have implemented the Atkinson-Brezovich limit to mitigate potential harm, recent research underscores discrepancies between this threshold and clinical outcomes, necessitating a re-evaluation of this safety limit. Therefore, in this study, through electromagnetic (EM) simulations, the complex interaction between AMFs and anatomical models was investigated.Approach.In particular, we considered a circular coil configuration placed at different positions along the craniocaudal axis of various anatomical human models. The excitation current was normalized, at different frequencies, to meet the basic restriction of local 10 g-averaged specific energy absorption rate (SAR) in the human models, as defined by the exposure guidelines of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) and the standard IEC 60601-2-33 of the International Electrotechnical Commission (IEC).Main results.The resulting permissible magnetic field strength values, for the reference levels set by the ICNIRP 2020 guidelines, emerged to be up to approximately 1.4 and 3 times less than that defined in the Atkinson-Brezovich limit. The widely used limit was found to align more closely with the first level of controlled operating mode defined in the IEC 60601-2-33 standard.Significance.The results indicate that the permissible magnetic field amplitude during MNH treatment should be much lower than that in the Atkinson-Brezovich limit. This study offers valuable insights into the role of computational simulations in advancing the potential to establish a reliable metric for safety evaluation and monitoring within the clinical framework of MNH.

Additive manufacturing of Fe-6.5Si cores with metal-insulator-metal structure via dual-nozzle material extrusion (MEX) technology

ABSTRACT This study proposes a novel approach for fabricating Fe-6.5 wt. %Si (Fe-6.5Si) soft magnetic cores using a dual-nozzle material extrusion (MEX) three-dimensional (3D) printing technology followed by a spark plasma sintering (SPS) process. A SiO2 insulator was printed between the Fe-6.5Si layers to fabricate metal–insulator-metal (MIM)-structured cores. Densified Fe-6.5Si soft magnetic cores (over 99%) were obtained owing to the resolution of the sintering problem with Fe-6.5Si because of its brittle nature using SPS. The magnetic core with a 0.2 mm-printed insulator (MC0.2) achieved a uniform insulator thickness of approximately 85 µm. Despite MC0.2 being approximately three times thicker than the single Fe-6.5Si layer (magnetic core single layer, MCS), a SiO2 insulator used in the cores of MC0.2 and MCS, resulted in comparable eddy current losses at 1 kHz. This highlighted the effectiveness of the MIM structure in suppressing the eddy currents. Thus, the proposed approach offers a promising solution for overcoming the geometric limitations of traditional stamping processes and paves the way for advanced magnetic core applications in additive manufacturing.

Design and analysis of the road energy harvester with an elastic element

This study introduces the integration of an elastic component into a speed bump-type energy harvester designed to generate power from the pressure exerted by passing vehicles. The research begins by presenting a passively actuated speed bump design, which serves as the input mechanism for the harvester and fully lowers when vehicles travel below a specific speed. Subsequently, a design equation integrating the elastic element into the energy harvester is formulated. Numerical simulations and experimental testing were conducted to evaluate the effects of the elastic element on the harvester’s performance. The results demonstrate that the elastic component can extend the duration of power generation, although it may reduce the peak power output. Additionally, the elastic element was found to reduce stress on the harvester’s transmission components, thereby improving its durability. These enhancements suggest that the elastic element could increase the viability of speed bump energy harvesters, particularly those employing electromagnetic induction, for practical road applications.

Induction heating boosts water splitting on iron–coated nickel foam

Abstract Alkaline water electrolysis at high temperatures can rival acidic proton-exchange membranes.
However, they suffer from increased energy consumption, reduced lifespan of materials and heightened safety risks. Magnetic hyperthermia is a method of localizing intense heating in the presence of an external high-frequency alternating magnetic field. In this study, we developed a custom electromagnetic induction device capable of generating a small magnetic field of about 2 µT. High-permeability nickel foam is used as electrodes. Results show that the iron coated nickel foam decreases the overpotential of the hydrogen evolution reaction and oxygen evolution reaction by ~150 mV and 60 mV, respectively, at 20 mAcm−2 when subjected to magnetic heating in a high-frequency alternating magnetic field. The overall water splitting current of Ni foam/Fe increases 540% under intermittent induction. The enhanced stability of Ni foam/Fe is attributed to the high binding energy of metal-O on the surface. The density function theory calculations further indicates that the lattice expansion of the metal electrode under induction heating optimizes the adsorption and desorption of H*, thereby enhancing the HER performance.

Detection of Sub-pT Field of Magnetic Responses in Metals and Magnetic Materials by Highly Sensitive Magnetoresistive Sensors

We developed a measurement system capable of detecting magnetic responses in various material samples. The system utilizes an excitation coil to apply an alternating magnetic field within the frequency range of 1–10 kHz. The magnetic field generated in the samples was detected using a highly sensitive magnetoresistive sensor. The system demonstrated a detection lower limit in the sub-pT range for magnetic fields arising from magnetic responses such as eddy currents and magnetization changes. The frequency dependence of the detected signal intensities correlated well with the physical mechanisms underlying the magnetic responses. Notably, the distance between the excitation coil and the magnetic sensor was maintained at 300 mm. These results, which demonstrate the detection of a sub-pT magnetic field using a highly sensitive magnetic sensor, have not been previously reported and provide valuable insights for advancing practical applications in non-destructive testing and clinical diagnostic imaging.

Aluminium foil micro-defect detection method based on motion-induced eddy current using differential TMR sensor spatial position compensation

ABSTRACT Lithium-ion batteries are a key technology in the energy storage field, and aluminum foil, a common cathode current collector, can develop micro-defects that significantly affect battery performance, especially during high-speed manufacturing. Motion-induced eddy current (MIEC) sensing is effective for detecting defects in conductive materials. However, lift-off fluctuations degrade the signal-to-noise ratio (SNR), making it challenging to detect small or shallow defects. Traditional methods, such as differential sensor outputs, help reduce these fluctuations, but baseline signal deviations caused by varying relative positions between the sensor and the permanent magnet limit their effectiveness. To address this, this study proposes a spatial compensation method for differential tunnel magnetoresistance (TMR) sensors, which reduces baseline deviations caused by position differences, mitigating lift-off fluctuations and improving the SNR for micro-defect detection.

Utilizing Flexible Magnetic-Alloy Sheet with Rolling-to-Attaching Method to Fabricate a Smart Nail for Electromagnetic Screw-Hole Targeting in Intramedullary Interlocking-Nail Surgery

Abstract In this paper, we present a novel method to fabricate a smart nail for electromagnetic targeting of distal screw-holes in intramedullary interlocking-nail surgery. The nail is fabricated by using a flexible magnetic-alloy Metglas sheet with a rolling-to-attaching method. That is, among most high permeable magnetic materials, the Metglas sheet has superior features in flexibility and bendability and therefore can be rolled and inserted inside the nail to accordingly conform to curvature of inner surface of the nail. Regarding the targeting system, we used a conventional c-shaped electromagnet (consisting of a c-shaped silicon steel core, emitting coil, and receiving coil) with measurement electronics as the targeting system. At first, an AC input voltage is applied to the emitting coil to generate magnetic flux in the air-gap between emitting coil and receiving coil. Consequently, by electromagnetic induction, an AC voltage is induced in the receiving coil. As the nail is axially moved or rotated within the air-gap between the emitting and receiving coils, the magnetic flux between the coils is influenced, leading to a change in the voltage output of the receiving coil. This voltage change is further analyzed to determine location and orientation of the Metglas sheet (as well as screw holes). Based on this targeting principle, we conduct location and orientation targeting tests. Results show that our method not only can successfully achieve these targeting, but also significantly simplifies the complexity of both targeting system and surgical procedure, in practical perspective.

A Previously Unknown Building Structure in Ancient Olympia (Western Peloponnese, Greece) Revealed by Geoarchaeological Investigations and Its Interpretation as a Possible Harbor

The ancient site of Olympia is located on the northern fringe of the Basin of Makrisia at the confluence of the Kladeos and Alpheios rivers (western Peloponnese, Greece) and was used as a venue for the Panhellenic Games from Archaic times until the 4th century AD. Geophysical prospection (frequency domain electromagnetic induction and electrical resistivity tomography) was carried out as a basis for detailed geoarchaeological investigations. In doing so, we identified a previously unknown building structure adjacent to the Altis, the inner part of the sanctuary at Olympia. Situated south of the Southwest Thermae, this structure measures at least 100 m (WSW-ENE) by 80 m (NNW-SSE). Its external orientation is in line with the orientation of the Southwest Thermae and the Leonidaion. We retrieved sediment cores from 17 different locations in combination with high-resolution direct push sensing from inside the newly found structure. All cores revealed distinct units of organic-rich limnic sediments dominated by clay and fine silt. Geochemical and micropaleontological analyses of selected sediment samples indicate highly eutrophic conditions, as evidenced by elevated phosphorous concentrations and the dominance of the ostracod species Cyprideis torosa, which is able to live under low-oxygen conditions. Moreover, molecular biomarker analyses show a significant input of lipid fecal markers, implying strong anthropogenic pollution. Further, the limnic sediments include numerous charcoal remains and abundant diagnostic artifacts such as ceramic fragments and building material. Radiocarbon dating documents that these limnic conditions persisted within the building structure from at least the 5th century BC to the 6th century AD. The identified building structure lies in the immediate proximity to the Lake of Olympia, which was recently found to have existed from the mid-Holocene to the Medieval period. Its characteristic filling with fine-grained sediments and multiple indications for a strongly polluted and heavily used standing water environment let us hypothesize that it was possibly used as a harbor installation. A harbor at ancient Olympia could have been used to reach the sanctuary by boat and to transport goods of all kinds.

Thermal Analysis of Electromagnetic Induction Heating for Cylinder-Shaped Objects.

Induction heating is one of the cleanest and most efficient methods for heating materials, utilizing electromagnetic fields induced through AC electric current. This article reports an analytical solution for transient heat transfer in a three-dimensional (3D) cylindrical object under induction heating. A simplified form of Maxwell's equations is solved to determine the heat generation inside the cylinder by calculating the current density distribution within the body. The temperature within the solid is found from the solution of the unsteady heat equation based on Green's function. Owing to multiple spatial dimensions and time, a separation of variables technique is used to find Green's function. In addition, an innovative algorithm is proposed to take care of the variable material properties in analytical treatment. The analytical solution for temperature is verified with the data obtained from experiments for identical operating conditions. The analytical solution is used to study the impact of heat transfer coefficient and input AC current frequency and amplitude during transient heat diffusion. Our analytical solution suggests that the temperature-dependent material properties significantly affect the thermal response within the solid. Unlike many other conventional heating methods, the thermal boundary condition changes with time in induction heating, which makes our solution much more challenging.

Electromagnetic induction properties of filamentous bacteria in sediment.

Microbial perception of spatial electromagnetic fields is essential for navigation and communication on Earth's surface system, but current understanding of this phenomenon is limited. At present, cable bacteria of the Desulfobulbaceae family have the longest known range of electron transport. In fact, the flow of electrons along these long filamentous bacteria generates an external electrostatic field, suggesting a potential for electromagnetic induction mirroring that of metallic wires. In this study, we measured the responses of cable bacteria to externally applied electric waves. We noted the formation and disappearance of square waves caused by a pair of spatially variable electric fields, generating negative and positive mirror-symmetric inductions (±1.20 mV in marine sediment) along the horizontally filamentous bacterial layer. Both seawater Candidatus Electrothrix and freshwater Ca. Electronema exhibited this electric induction. The distinct spatial boundary of bacterial induction was strictly confined within 12.5 mm below the surface of the seawater sediment. The results of this study open further avenues of research into understanding how bacteria sense and respond to spatial electromagnetic information.

Towards the Measurement of Sea-Ice Thickness Using a Time-Domain Inductive Measurement System.

Frequency-domain electromagnetic induction (EMI) is routinely used to detect the presence of seawater due to the inherent electrical conductivity of the seawater. This approach is used to infer sea-ice thickness (SIT). A time-domain EMI sensor is presented, which demonstrates the potential for correlating the spectroscopic properties of the received signal with the distance to the sea surface. This is a novel approach to SIT measurement, which differs from existing methods in that it uses measurements from 10 kHz to 93 kHz rather than a single frequency. The sensor was tested at a tidal pool containing seawater and measured to have a conductivity of 57.3 mS/cm. Measurements were performed at a range of heights between 0.2 m and 1.9 m above the sea surface and for inclinations from 0° to 45°. These measurements were correlated with Finite Element Modeling (FEM) simulations performed in COMSOL. The measured and simulated datasets are presented along with a proposed form of post-processing, which establishes a correlation between the distance to the sea surface and the measured EMI response. This forms a proxy measurement for the absolute distance from the EMI sensor to the sea surface. Because the air gap between the sensor and the seawater is indicative of the properties of sea ice, this study demonstrates a novel approach to non-destructive measurement of sea-ice thickness. The measurements show that this distance to the sea surface can be estimated to within approximately 10% of the known value from 0.2-1.5 m and 15% from 1.5 to 1.9 m.