Induced Research Articles

Enhancement of laser ablation via high-frequency electromagnetic induction heating

The efficiency of pulsed laser ablation has always been the focus point of research. A novel high-frequency electromagnetic induction heating-assisted laser ablation scheme is proposed and investigated to enhance the efficiency and improve the surface processing quality during the nanosecond laser ablation of metal substrates. To reduce laser energy required to reach the ablation threshold of metal, this method utilizes the electromagnetic induction to rapidly elevate substrate temperature, making the metal easier to be ablated. The results show that ablation width increases 16% and ablation depth increases 31% with the assistance of electromagnetic induction heating at a laser fluence of 1.32 J/cm2, which increases 90% of the laser-ablated volume. Meanwhile, the surface ablation quality is significantly improved due to the smaller temperature gradient around the ablation region. This new method has great potentials in the laser micromachining at a higher processing efficiency and better laser-processed surface quality.

Study of the effect of electromagnetic damping force on a magnet oscillating near a non-ferromagnetic conducting plate

Abstract We have designed an experiment that involves studying the effects of a conducting plate on the motion of an oscillating disc magnet. We have employed the video analysis method by ‘Tracker’ software to investigate the variation of electromagnetic damping coefficient with distance between the plate and the magnet. This experiment can indeed serve as a valuable educational tool for undergraduate students, covering topics such as damped oscillation, electromagnetic damping, Lenz's law, and eddy currents.

Effect of aging level on the healing properties of an induction-heated ultra-thin wearing course and its mechanism

Electromagnetic induction heating can accelerate crack self-healing in asphalt concrete and extend its service life. In the maintenance project of existing pavements, induction heating and ultra-thin wearing course can be combined by paving functional induction heating wearing course. However, the ultra-thin wearing course is directly affected by the environment and loading, and undergoes aging in the service process. Thermo-oxidative aging is an irreversible and important mechanism that seriously affect the rheological and healing properties of asphalt. Therefore, the purpose of this work is to examine the impact of thermo-oxidative aging on the induction heating-healing of an ultra-thin wearing course mixture. Firstly, the AC-5 induction heated ultra-thin wearing course (IHUC) containing 1 % steel wool fiber by aggregate mass was prepared. Subsequently, the IHUC was aged to six different levels. Then, the induction heating and healing properties of the aged IHUC were evaluated. Simultaneously, the aged asphalt binder was extracted and its rheological characteristics and chemical alterations were studied. The outcomes showed that the heating rate of IHUC decreased, but the temperature gradient effect reduced at higher aging level. The optimal healing temperature of IHUC shifted to a higher temperature region and the healing rate decreased. Both heating cycles and thermo-oxidative aging reduce healing effectiveness, but the impact of heating cycles is less compared to aging. Rheology and chemical structure test results of extracted asphalt binder showed that the transformation of the molecular structure caused the fluidity and self-healing properties of asphalt were decreased. This ultimately decreased the healing rate of IHUC.

Lift-Off Effect of Koch and Circular Differential Pickup Eddy Current Probes

A flexible or planar eddy current probe with a differential structure can suppress the lift-off noise during the inspection of defects. However, the extent of the lift-off effect on differential probes, including different coil structures, varies. In this study, two planar eddy current probes with differential pickup structures and the same size, Koch and circular probes, were used to compare lift-off effects. The eddy current distributions of the probes perturbed by 0° and 90° cracks were obtained by finite element analysis. The analysis results show that the 90° crack can impede the eddy current induced by the Koch probe even further at relatively low lift-off distance. The peak-to-peak values of the signal output from the two probes were compared at different lift-off distances using finite element analysis and experimental methods. In addition, the effects of different frequencies on the lift-off were studied experimentally. The results show that the signal peak-to-peak value of the Koch probe for the inspection of cracks in 90° orientation is larger than that of the circular probe when the lift-off distance is smaller than 1.2 mm. In addition, the influence of the lift-off distance on the peak-to-peak signal value of the two probes was studied via normalization. This indicates that the influence becomes more evident with an increase in excitation frequency. This research discloses the lift-off effect of differential planar eddy current probes with different coil shapes and proves the detection merit of the Koch probe for 90° cracks at low lift-off distances.

Design of a system for detection of non-ferromagnetic metallic foreign bodies based in eddy currents and GMI magnetometer

A portable magnetic mapping system was designed to determine the three-dimensional location of non-ferromagnetic metallic foreign bodies to ensure fast and successful surgical procedures for their removal. The system is based on the induction of eddy currents in the foreign body by an excitation stage and the measurement of the magnetic field generated by these currents employing a commercially available high-resolution magnetometer based on the Giant Magneto-Impedance effect. The instrument topology is based on decoupling the excitation and measurement stages with a configuration that produces a high primary magnetic field in the foreign body region and a weak one in the GMI sensor region. This feature allows increasing the primary excitation magnetic field without saturating the GMI magnetometer, making it feasible to overcome relevant limitations evidenced in a previously developed instrument proposal. Computational simulations were built considering four possible configurations, with two models of excitation and two options for the magnetometer GMI sensitivity axis orientations. International guidelines for exposure limits to non-ionizing radiation and the principles of biometrology, besides constructive and electrical aspects, were also considered in the system design. The performance analysis of the most promising settings confirmed the viability of the proposed measuring instrument, optimizing the linear operation of the magnetometer during the measurement procedure and contributing to the construction of a complete measurement system prototype, with performance and safety characteristics ensured for the intended biomedical application.

Advancements in Continuum Mechanics and Electrodynamics by a spacetime geometric approach

AbstractResults achieved by the authors in the course of research activity on continuum mechanics and electrodynamics (CME) during the past twenty years are illustrated, revised and discussed. Adoption of a geometric approach leads to renewal of concepts and methods of classical CME and to formulation in Euclid (3+1)D ambient spacetime wherein innovation, clarity and depth of a geometric treatment naturally emerge. The dissemination of novel concepts and methods in CME is not delayable, with critical revisitation of problematic notions, analyses and results still currently on the scene. Material frame indifference, equilibrium in a reference configuration, extremality principles in Dynamics, finite elasticity, chain decomposition of finite strain in elasto-thermo-plasticity, variance of electro-magnetic induction laws under frame changes, action on electric charges moving in a magnetic field, are under the spotlight of innovation and advancement. Fostering basic knowledge of Differential Geometry and application of geometric notions and methods contribute effective tools in formulating meaningful rules, amending misstatements and dimming debates based on vague affirmations.

Generation mechanism and empirical model of eddy current force and torque in drum-type eddy current separation

Enhancing the recovery efficiency of non-ferrous metals in eddy current separation is of great significance. In this study, the accuracy of the simulation model was verified by comparing the eddy current force. The transformation mechanism of the Lorentz forces into the eddy current force and torque in non-ferrous metal particles was revealed by analyzing various physical fields. Then, the influence of magnetic field parameters on eddy current, eddy current force, and torque was studied. It shows that the eddy current force and torque are affected by the vector gradient of the magnetic field and the magnetic flux density, respectively. Additionally, the time derivative of the magnetic field impacts the magnitude of the eddy current force and torque by controlling the eddy current. On this basis, the empirical models of eddy current force and torque were established by similarity theory. The results obtained can improve and expand the application of eddy current separation.

The configuration and detection characteristics of a 3D holographic LWD instrument antenna system based on multi-component EM induction theory

In order to improve the precision of electromagnetic resistivity logging, while ensuring the reliability of boundary detection and anisotropy identification, this study starts from the theory of multi-component electromagnetic induction. Through deriving the formula of component responses, the analytical expressions of electromagnetic wave fields are obtained for various coil pairs of azimuthal instruments. A 3D holographic LWD instrument antenna configuration is constructed, with co-planar and non-coplanar, tilted and orthogonal coil combinations, all components of the magnetic field tensor Hxx,Hxy,Hxz,Hyx,Hyy,Hyz,Hzx,Hzx,HzzHxx,Hxy,Hxz,Hyx,Hyy,Hyz,Hzx,Hzx,Hzz are successfully resolved. With the combination of some or all components, functional signals are generated for specific detection objectives. Numerical simulation of the response of those signals shows that the distance of boundary detection and anisotropy identification capability are superior to traditional geo-signals. The response relationship shows that as the contrast of the formation resistivity decreases and the well deviation angle increases, the anisotropy identification capability gradually strengthens, and the signal strength and identification capability are better at frequency in the range of 400–600 kHz. The proposed antenna configuration has the potential to significantly enhance formation evaluation and to improve geo-steering capability, contributing technology-wise to the optimal landing trajectory and best wellbore position, resulting in cost saving and maximize oil & gas production.

Processing map for touch‐free flash sintering of a whiteware ceramic

AbstractFlash sintering has evolved into touch‐free sintering, where free‐standing workpieces can be sintered without attaching electrodes. Instead, the flash is transmitted from the surface of a reactor into the workpiece with superimposition of a magnetic field. Thus, sintering now depends on two independent parameters: the current used to sustain the flash in the reactor and the current flowing through the induction coil. We present a first report on the influence of these two parameters on the quality of the sintered workpiece. The specimens were made from whiteware, consisting of aggregates of ceramic particles interspersed with particles of a glass phase. The results are presented in a map with the reactor current and the induction current as the control variables. Three regimes are identified: insufficient sintering, good sintering, and the formation of defects. The reactor current emerges as an important variable: densification is poor if it is too low, and defects form if it is too high, with high density achieved in the intermediate regime. High induction currents are needed to achieve good sintering. Touch‐free flash sintering has also been shown to sinter and at the same time transform powders of elemental oxides into a single‐phase multicomponent ceramic.

Performance improvement of metal hydride hydrogen compressors using electromagnetic induction heating

While there are some hydrogen refueling stations (HRS) functioning in different parts of the world, their use is not widespread enough, primarily due to their expensive cost. Hydrogen compression is a main contributor to the capital and operation costs of the HRS. By improving H2 compression technology, it is possible to optimize the infrastructure for refueling with hydrogen in terms of cost and performance. The use of metal hydride hydrogen compressors (MHHCs), which have the potential to be inexpensive and have the ability to use waste heat and renewable energy sources for the H2 compression, is a promising solution to overcome this issue. The duration of the H2 compression cycle is nevertheless a serious challenge due to the metal hydride (MH) bed's low heat conductivity. As a heating technique to improve the performance of MHHCs, electromagnetic induction (EMI) is examined numerically for the first time in this work. The dynamic behavior of a two-stage MHHC with each MH reactor having an external heat exchanger and being ringed by a copper coil traversed by an alternating current is described by a two-dimensional mathematical model, which was established and successfully verified by the reference data. Numerical simulations were performed with the help of this model, and the findings showed that the EMI heating method is faster than the heat transfer fluid (HTF) heating technique. For instance, at a delivery temperature of 373 K and a supply pressure of 20 bar, it is possible to produce 106 NL H2 per kilogram of HPMH at a pressure of 97 bar with a 74 % shorter compression time than with the HTF heating technique.

Experimental study of the importance of fibre breakage on the strength of thermoplastic matrix composites subjected to compression after impact

Post-impact strength and damage tolerance of composite structures stands as a paramount design consideration in the aeronautical industry. In the event of a low velocity impact, a set of damage manifestations within laminated structures are induced, including matrix cracking, delamination and fiber breakage. Despite the critical importance of discerning the influence of each damage type on post-impact compression strength, only a limited number of studies have endeavored to quantify these effects comprehensively. In response to this research gap, we have developed a novel methodology capable of mimicking damage extension and shape caused by a low-velocity impact, while preserving fiber integrity. This innovation is achieved through the application of induced electrical currents, thereby facilitating controlled damage simulation without compromising fiber structural integrity. Our investigation compares the residual stiffness and strength of AS4/PEEK laminates subjected to low velocity impacts and induction currents, under conditions of equivalent damage. Our findings reveal that fiber breakage significantly influences the loss of stiffness in the laminate, but not its strength. Moreover, our results confirm the role of delamination as the primary determinant of strength degradation in the damaged material.

Bolt loosening monitoring with passive wireless-based smart washers

Ensuring sufficient preload of bolted connections is crucial for maintaining the safety of railway operations. Accidents resulting from loose bolts caused by inadequate preload are a recurring concern. Traditional bolt preload detection methods suffer from reliability issues and bulky equipment requirements. To address these challenges, this study proposes a novel solution utilising passive wireless measurement systems. However, the communication effectiveness of these systems can be significantly impacted by the surrounding metal environment. This research introduces an intelligent clover washer design to mitigate the adverse effects of eddy currents induced by the metal environment. The design incorporates a new clover antenna and washer structure, effectively reducing the influence of the metal environment and improving the communication quality. The proposed design has undergone comprehensive prototyping, simulation and experimental verification. The results demonstrate a significant improvement over the traditional circular antenna and washer combination under similar conditions. Specifically, the sensing distance of the new clover washer is enhanced by 60% and the stable communication distance is improved by 75%. The experimental results highlight the ability of the new clover smart washer to generate a stronger spatial magnetic field and exhibit reduced susceptibility to the metal washer, thereby enhancing communication effectiveness.

Thermal measurements of boiling granular films.

This study focused on two familiar items in our daily lives: grains and boiling water. Accurately measuring boiling dense granular beds requires specialized instruments and novel techniques. An annular vertical riser was used to boil granular films. The riser was filled with glass beads and then immersed in liquid water. The water is heated by inducing eddy currents at the base of the riser, which is composed of carbon steel. Beyond the critical electric current, Ic, the Lyapunov exponent of the time series of the measured temperature distributions within the granular films became positive. This indicates the chaotic behavior of the films. Slightly above Ic, patterned instabilities with affine fractal-like structures were observed in the boiling granular films. Chaotic boiling granular films manifested percolation and transition to turbulence. Computer simulations of the above system under the guidance of generative AI (GenAI) successfully reproduced many critical features of the experimental observations, which can be considered a significant breakthrough in the modeling and simulation of complex systems. With this success in utilizing GenAI, more accurate instruments can be developed, resulting in the world of tomorrow rapidly becoming today's world.

3D printing of ferromagnetic passive shims for field shaping in magnetic resonance imaging

Magnetic Resonance Imaging (MRI) often encounters image quality degradation due to magnetic field inhomogeneities. Conventional passive shimming techniques involve the manual placement of discrete magnetic materials, imposing limitations on correcting complex inhomogeneities. To overcome this, we propose a novel 3D printing method utilizing binder jetting technology to enable precise deposition of a continuous range of concentrations of ferromagnetic ink. This approach grants complete control of the magnitude of the magnetic moment within the passive shim enabling tailored corrections of B0 field inhomogeneities. By optimizing the magnetic field distribution using linear programming and an in-house written Computer-Aided Design (CAD) generation software, we printed shims with promising results in generating low spherical harmonic corrections. Experimental evaluations demonstrate feasibility of these 3D printed passive shims to induce target magnetic fields corresponding to second-order spherical harmonic, as evidenced by acquired B0 maps. The electrically insulating properties of the printed shims eliminate the risk of eddy currents and heating, thus ensuring safety. The dimensional fabrication accuracy of the printed shims surpasses previous methods, enabling more precise and localized correction of subject-specific inhomogeneities. The findings highlight the potential of binder-jetted 3D printed passive shims in MRI shimming as a versatile and efficient solution for fabricating passive shims, with the potential to enhance the quality of MRI imaging while also being applicable to other types of Magnetic Resonance systems.

Enhancing the catalytic H2 production performance of magnetic Ni-Fe2O3-C catalyst in biomass steam gasification using electromagnetic induction heating

In this study, a novel magnetic Ni-Fe2O3-C catalyst combined with electromagnetic induction heating in bioamass steam gasification was proposed to enhance H2 production. Better catalytic performance for H2 production was observed with the Ni-Fe2O3-C catalyst under induction heating, resulting in an increase in H2 yield from 735.1 to 2271.2 mL/g-biomass (a 209.1 % enhancement). SEM, TGA and XRD analysis demonstrated a significant decrease in coking deposition, caking, and particle agglomeration of the Ni-Fe2O3-C catalyst under induction heating, while maintaining more active sites. Importantly, the benefits of induction heating were also applicable to different magnetic catalysts like Ni-Al2O3-C, Ni-ZrO2-C, and Ni-MgO-C. Experimental results revealed a logarithmic correlation between the increase in H2 yields due to induction heating and the magnetic saturation (Ms) of the catalysts. The Ni-Fe2O3-C catalyst, with a high Ms of 50.9 emu/g, showed the highest catalytic activity for H2 production under induction heating in this study.

Experimental study on preheating and salt circulation performance of a single receiver tube based on induction heating

The design of a light source for a molten salt receiver experimental system has become challenging owing to the complex heating characteristics of the half-circumference surface during operation. Electromagnetic induction heating is an innovative technology that can replicate a half-circle heating scenario. However, its feasibility must be verified. In this study, we constructed a single receiver tube experimental system using induction heaters and developed a 3D numerical model coupling electromagnetic field to analyze the tube temperature distribution and molten salt temperature rise during preheating and salt circulation, considering various parameters. The results indicated that the numerical simulation agreed well with the experimental results, and the induction heater successfully reproduced the half circumference heating scenario. During preheating, a lower heat flux and higher wind speed result in a more uniform temperature distribution along the circumference of the tube wall, facilitating comprehensive preheating. During salt circulation, the heat flux and inlet salt mass flow significantly affected the temperature of the tube wall but had a relatively small effect on the back-side wall. Wind speed had the opposite effect, which was related to the arrangement of the experimental site. A higher heat flux, lower wind speed, and higher inlet salt mass flow led to a higher temperature increase in the molten salt.

Learning with multiple external representations in physics: Concreteness fading versus simultaneous presentation

AbstractMultiple external representations (MERs) are useful for teaching complex content in science education. An open question is whether there is an especially effective way to sequence MERs. On the one hand, the so‐called concreteness fading approach suggests starting instruction with more concrete representations and proceeding stepwise to more idealized representations. The effectiveness of this fading approach is, however, supported mainly by studies in mathematics education, while the results in physics are equivocal. On the other hand, presenting different representations simultaneously may support linking, that is, the comparison and contrast of representations, which may benefit learning. In an experimental classroom study (N = 187), we compared concreteness fading and simultaneous presentation of MERs for learning a challenging physics content in high school, namely, Faraday's law. We found no significant differences between conditions in posttest performance, and an equivalence test with bounds d = −0.5 to 0.5 showed that both approaches performed equally. The results align with previous findings questioning the superiority of concreteness fading over other ways of sequencing MERs. Therefore, facilitating students' understanding of a complex physics content may involve more than determining the optimal order of presenting MERs. We discuss limitations of the present study and implications for future research and practice.

Photons in Physics with real Magnetic Charges and the Falsity Existing Notion of Expansion Universe (How Physicists; "Yawn" Real Magnetic Charges, Curved Space and Sentenced the Universe to Expansion)

The experiments of F. Ehrenhaft as well as the experimental and theoretical studies of the author showed that it is magnetic charges are the direct sources of the magnetic field. Eddy currents of magnetic charges (rotating magnetic dipoles g- - g+) which actually exist in atoms and substance, are untwisted by electric current in conductors, are direct sources of the well-known vortex magnetic field rotH. Together with electric charges, magnetic charges make up the shells of atoms, which are actually electromagnetic, not electronic. It is the electromagnetic shells of atoms that are the sources of the vortex electromagnetic (gravitational) field, which is described by the vortex vector rot[E – H]. The vector character of GF is in many respects similar to the vortex magnetic field, which has been known for hundreds of years, but no one has come up with the version of spatial magnetic waves. Therefore, the notion of gravitational waves, according to the author, is another fake, inspired by crooked physics, in which there is absolutely no representation of the real physics of the gravitational field. The introduction of real magnetic charges into the basic physical representations, as well as the discovery by the author of the World Physical Triad, made it possible to clarify the essence of spinor fields which are flows of elementary particles of the world Energo-medium, which are formed by spinor (charged) particles. In addition, the article proves that the concept of the expansion of the Universe was the result of E. Hubble's erroneous (extremely superficial) perception, back in 1929, of the manifestation of the cosmological redshift of the photon frequency, which he interpreted as a Doppler shift in the frequency of the so-called light waves. The inclusion of real magnetic charges in the physical representations showed that the frequency processes in photons are determined exclusively by the intra-photon physics embedded in into at the moment of formation and cannot be the result of any spatial wave formations in the environment, i.e. the shifts of photonic frequency ∆ω have nothing to do with the Doppler effect and depend only on changes in the translational velocity of their source. In other words, the redshift of the photon frequency under the conditions of the translational motion of their sources is exactly the same, both in the case of the source moving to the observer, and in the case of its movement at the same speed away from the observer. As for the violet shift of the photon frequency, this is an unambiguous sign of the rotational dynamics of photon source, and in the case of combined motion of source (translational and rotational), the mechanism of photon frequency pulsations is possible.

Remote measurement of transient heat flux based on the thermomagnetic effect

Abstract Heat flux is a physical quantity that characterises the strength of heat transfer per unit area. Heat transfer occurs with a temperature difference. Herein, a remote heat flux measurement method based on the thermomagnetic effect is proposed. Using Bloch’s law, Faraday’s law of electromagnetic induction, and Fourier’s law, a temperature measurement model from heat flux to magnetisation of the magnetic film and finally to the induced electromotive force in the Helmholtz coil is established. A compression corner was fabricated, and the heat flux measurement method was experimentally verified in a Mach 6 shock tube wind tunnel. In addition, a Schlieren experiment was performed for comparison. In the experiments, the temperature resolution of the magnetic film reached 0.36 K, and the temperature response reached 100 kHz. The range of the proposed heat flux measurement method is up to 5 MW m m − 2 , and the measurement error is less than 10%. At a resolution of 10 μs, the change in heat flow is mapped when there is a transition for the magnetic film from flat to turbulent flow, which shows the different effects of hypersonic heat flux on the boundary layer and attachment position. The magnetic thin film shows the potential for heat flux estimation in our experiment.

Enhancing Electrical Conductivity of Stretchable Liquid Metal-Silver Composites through Direct Ink Writing.

Structure-property-process relationships are a controlling factor in the performance of materials. This offers opportunities in emerging areas, such as stretchable conductors, to control process conditions during printing to enhance performance. Herein, by systematically tuning direct ink write (DIW) process parameters, the electrical conductivity of multiphase liquid metal (LM)-silver stretchable conductors is increased by a maximum of 400% to over 1.06 × 106 S·m-1. This is achieved by modulating the DIW print velocity, which enables the in situ elongation, coalescence, and percolation of these multiphase inclusions during printing. These DIW printed filaments are conductive as fabricated and are soft (modulus as low as 1.1 MPa), stretchable (strain limit >800%), and show strain invariant conductivity up to 80% strain. These capabilities are demonstrated through a set of electromagnetic induction coils that can transfer power wirelessly through air and water, even under deformation. This work provides a methodology to program properties in stretchable conductors, where the combination of material composition and process parameters leads to greatly enhanced performance. This approach can find use in applications such as soft robots, soft electronics, and printed materials for deformable, yet highly functional devices.