Induced Research Articles

In-situ 3D temperature field modeling and characterization using eddy current for metal additive manufacturing process monitoring

Metal additive manufacturing (AM) is a critical capability for Industry 4.0, with particular potential in the aerospace and medical industries. Its ability to create dense metal parts with intricate geometries makes it appealing for demanding environments requiring specific thermal and mechanical properties, as well as long-term reliability. Despite its potential, challenges such as low surface quality and buried porosity have impeded the widespread adoption of metal AM. Therefore, advances such as real-time monitoring of AM processes are necessary to realize the full capability of these new manufacturing methods. Here we examine the feasibility of one promising approach: eddy current (EC) measurements for in-situ LPBF AM temperature monitoring, which is different from existing EC method to monitor near surface porosity or crack. The temperature-dependent electrical conductivity of many materials used in AM processes suggests it may be possible to measure the internal temperature using an eddy current probe. These measurements of the temperature history could then inform the quality of build layers, such as internal stress, which would otherwise be inaccessible to characterization. We first developed a thermally-coupled electromagnetic simulation to examine this phenomenon. Our model reveals a complex internal temperature distribution created during dynamic laser heating processes. Notably, the simulation also indicates that the EC response can dynamically reflect the temperature of the AM material during both the heating and cooling processes. We performed experiments to validate our simulations, using a soldering iron tip as a point heating source on a metal plate, together with a commercial EC apparatus. The results showed that this method can achieve real-time temperature monitoring in the range 420–700 K, suggesting potential for addressing a critical need process monitoring need for enhancing metal AM processes.

Simultaneous quantitative detection of thinning defects on the connection surface of heterogeneous metal plates

Abstract The significant difference in electromagnetic properties between aluminum and steel makes detecting corrosion thinning defects at their interface particularly challenging. In this study, we propose a method for the simultaneous detection and quantification of corrosion thinning defects at the interface of double-layered heterogeneous metal plates using pulsed eddy current (PEC) technology. First, a finite element simulation model was developed to classify and identify feature signals through principal component analysis (PCA). Next, a novel approach based on Characterization Feature Points (CFP) was introduced to detect and quantitatively evaluate corrosion thinning defects at the aluminum-steel interface. Finally, an experimental system was constructed, and comprehensive experimental studies were conducted. The results demonstrate that the proposed method can effectively distinguish and quantify corrosion thinning defects at aluminum-steel interfaces. Among the simultaneous quantification methods, the method based on Characterization Feature Point Time (CFPT) exhibits a maximum relative measurement error of 33.54% and a minimum of 2.06%. In contrast, the method based on Characterization Feature Point Amplitude (CFPA) demonstrates significantly lower errors, with a maximum relative measurement error of 5.95% and a minimum of 0.24%. This study presents a novel approach for the differentiation and simultaneous quantification of corrosion thinning defects in double-layer heterogeneous metal plates.

The origins of neuromuscular electrodiagnosis. 1800-1950: a crucial period.

The two components of today's electroneuromyography (i.e. neurography and myography) gradually emerged from the harmful practice of electrotherapy during the crucial period of 1800-1950. At the beginning of the 19th century, galvanism was supplemented by the fashionable induction coils created by Heinrich Daniel Ruhmkorff (1803-1877). In the same decades, major physiological research was performed by the Italian Carlo Matteuci (1811-1868), the Germans Emil Heinrich du Bois Reymond (1818-1896) and Eduard Pflüger (1829-1910) and the French Claude Bernard (1813-1878). This led to the description of the nerve action potential and to the measurement of the speed of nerve impulses in frogs by Hermann von Helmholtz (1821-1894). In the mid-19th century, Guillaume Duchenne de Boulogne (1806-1875) designed his own electrical equipment to perform faradisation, a focal electrification using induction current. Duchenne's methodology and conclusions led to a heated debate with Robert Remak (1815-1865) about the use of galvanic current, and with Hugo von Ziemssen (1829-1902) about the points which were to become the motor point. In the following years, the galvanic polar method was developed. Rudolf Brenner (1821-1884) formalised a literal notation of this method, expressing the muscle contraction formula by a system of letters. From the 1880s, a standardisation of electrodiagnostic exploration began. The German neurologist Wilhelm Erb (1840-1921) formalised a more complex situation called Entartungsreaktion (degenerative reaction). During WW1, a bipolar method was used and André Strohl (1887-1977) performed the electrical recording of tendon reflexes. Myography emerged in the first years of the 20th century thanks to the physiological work of Keith Lucas (1879-1916) and Charles Sherrington (1857-1952). The concentric needle, designed by Edgar Adrian (1889-1977) and Detlev Bronk (1807-1975), and the development of the cathode-ray oscilloscope were of great interest for electromyography. Such oscilloscopes also allowed Joseph Erlanger (1874-1965) and Herbert Gasser (1888-1963) to graph the action potential of a frog's sciatic nerve. During WW2, the American James G. Golseth (1912-2003) and James A. Fizzell (1912-1995) worked with the Canadian Herbert H. Jasper (1906-1999). They demonstrated the importance of interpreting myography and neurography together. In England, Herbert Seddon (1903-1977) and Graham Weddell (1908-1990) described the evolution of nerve injuries and muscle denervation on wounded soldiers. In the 1950s, the first widespread marketing of electromyographic devices allowed a new generation of neurologists to be invested in this novel topic.

Micromagnetic stimulation (μMS) controls dopamine release: an in vivo study using WINCS Harmoni

Research into the role of neurotransmitters in regulating normal and pathologic brain functions has made significant progress. Yet, clinical trials that aim to improve therapeutic interventions do not take advantage of thein vivochanges in the neurochemistry that occur in real time during disease progression, drug interactions or response to pharmacological, cognitive, behavioral, and neuromodulation therapies. In this work, we used the WINCSHarmonitool to study the real timein vivochanges in dopamine release in rodent brains for the micromagnetic neuromodulation therapy. Although still in its infancy, micromagnetic stimulation (μMS) using micro-meter sized coils or microcoils (μcoils) has shown incredible promise in spatially selective, galvanic contact free and highly focal neuromodulation. These μcoils are powered by a time-varying current which generates a magnetic field. As per Faraday's Laws of Electromagnetic Induction, this magnetic field induces an electric field in a conducting medium (here, the brain tissues). We used a solenoidal-shaped μcoil to stimulate the medial forebrain bundle (MFB) of the rodent brainin vivo. The evokedin vivodopamine releases in the striatum were tracked in real time by carbon fiber microelectrodes (CFM) using fast scan cyclic voltammetry (FSCV). Our experiments report that μcoils can successfully activate the MFB in rodent brains, triggering dopamine releasein vivo. We further show that the successful release of dopamine upon micromagnetic stimulation is dependent on the orientation of the μcoil. Furthermore, varied intensities of μMS can control the concentration of dopamine releases in the striatum. This work helps us better understand the brain and its conditions arising from a new therapeutic intervention, like μMS, at the level of neurotransmitter release. Despite its early stage, this study potentially paves the path for μMS to enter the clinical world as a precisely controlled and optimized neuromodulation therapy.

Detecting Defects in Materials Using Nondestructive Microwave Testing Techniques: A Comprehensive Review

Microwave nondestructive testing (MNDT) has shown great potential in detecting defects in various materials. This is due to it being safe and noninvasive. Safety is essential for the operators as well as the specimens being tested. Being noninvasive is important in maintaining the health of critical structures and components across various industries. In this paper, a review of MNDT methods is given with a comparison against other NDT techniques. First, the latter techniques are described, namely testing using a dye penetrant, ultrasound, eddy currents, magnetic particles, or radiography. Next, an overview of various microwave NDT methods is provided through a review of the applications, advantages, and limitations of each technique. Further, a detailed review of emerging MNDT techniques like microwave microscopy, active microwave thermography, and chipless radio frequency identification is presented. Next, a brief description of current and emerging algorithms employed in MNDT is discussed, with emphasis on those using artificial intelligence. By providing a comprehensive review, this article aims to shed light on the current state of MNDT, thus serving as a reference for subsequent innovations in this rapidly evolving domain.

Magnetic Field‐Assisted Conductive Nerve Guidance Conduit Enabling Peripheral Nerve Regeneration with Wireless Electrical Stimulation

AbstractNerve guidance conduits capable of wireless stimulation represent a promising approach for addressing peripheral nerve defects. However, traditional electrical stimulation methods are not sufficiently convenient and may cause secondary damage. In this study, a conductive nerve guidance conduit combined with wireless electrical stimulation using alternating magnetic fields is presented. The conduit coated with nanographene and incorporated with Fe3O4 nanoparticles induces currents and creates a supportive microenvironment enhancing nerve regeneration. Finite element analysis confirms that the conduit generates electromotive force under an external alternating magnetic field. The conduit exhibits improved morphology, physicochemical properties, and conductivity by six orders of magnitude. In vitro experiments demonstrate that the conduit promotes Schwann cell proliferation, migration, and intercellular communication through microcurrents, as well as neuronal axon extension. TEM images confirm axon extension and myelin sheath thickness, indicating its high conductivity and efficiency in promoting nerve regeneration across defects. In vivo studies show that the conduit generated microcurrent using wireless electromagnetic stimulation, significantly enhancing myelin restoration, gastrocnemius muscle regeneration, motor function recovery, and nerve tissue growth, achieving results comparable to the gold‐standard autograft method. Overall, this work highlights the effectiveness of electromagnetic induction in nerve repair and presents a new, non‐invasive stimulation for peripheral nerve regeneration.

Black Phosphorus Enabled Non Invasive Protein Detection with electromagnetic induction well Terahertz Biosensor Chips

Black Phosphorus Enabled Non Invasive Protein Detection with electromagnetic induction well Terahertz Biosensor Chips

Resistivity measurement for non-magnetic materials using high-order resonance mode of MFM-cantilever oscillation

Abstract A method to measure the electrical resistivity of materials using magnetic- force microscopy (MFM) is discussed, where MFM detects the magnetic field caused by the tip-oscillation-induced eddy current. To achieve high sensitivity, a high cantilever oscillation frequency is preferable, because it induces large eddy currents in the material. Higher-order resonance modes of the cantilever oscillation lead to higher frequency. To discuss such high-order-mode oscillation, a differential equation governing MFM cantilever oscillation in the high-order resonance mode is formulated, and an analytical solution of the phase difference is obtained. The result shows that the phase difference decreases at higher modes, because the effective spring constant increases faster than the force from the eddy current.

Sequential multi‐dimensional parameter inversion of induction logging data

AbstractStructural information about the subsurface near the borehole can be obtained from reconstructed conductivity distributions. These distributions may be reconstructed via the inversion of deep‐sensing electromagnetic induction log data. Unfortunately, these complex media often display anisotropy and structural variations in both horizontal and vertical directions, making the three‐dimensional inversion computationally demanding and ill‐posed. To address these challenges, we introduce a sequential inversion strategy of deep‐sensing electromagnetic induction logging data that is measured while drilling. For the inversion at each logging position, we employ a matrix‐free implementation of the adjoint integral equation method and a quasi‐Newton algorithm. To tackle the ill‐posed nature of the problem, we regularize the inverse problem by employing a multi‐dimensional inversion parameter technique that shifts from zero‐ to three‐dimensional parameterization. The model derived from the inversion of the data at multiple positions is incrementally integrated by utilizing the sensitivity data at each logging position. To validate our approach, we tested our method on simulated data using an anisotropic model. These experiments show that this approach produces a good reconstruction of the true conductivity for the whole track while only doing the inversion at a single position at a time.

Efficient and accurate pulsed eddy current modelling: enhancing BPNN performance through Box-Cox transform

ABSTRACT The current modelling method for pulsed eddy current (PEC) based on the BP neural network (BPNN) exhibits certain limitations. Specifically, when the amplitudes of impedance changes are small, the relative errors of the BPNN prediction results become notably large, which in turn leads to poor modelling accuracy of the PEC signal. To address this issue, this paper proposes an improved BP neural network (IBPNN) method, which combines the Box-Cox transform with BPNN. Firstly, the Box-Cox transform is used to process the sample data, effectively reducing the data skewness and amplifying the impedance changes with smaller amplitudes. Subsequently, the mapping of the lift-off, thickness, and frequency with the impedance change after the Box-Cox transform is established through BPNN. By comparing the influence of different data transform methods on BPNN, it is found that the Box-Cox transform significantly improves the prediction accuracy of BPNN. Eventually, the correctness and effectiveness of the IBPNN method are verified by matching with the experimental signals provided by the reference. This study not only demonstrates the advantages of the Box-Cox transform in dealing with nonlinear data but also provides new ideas for improving the accuracy and reliability of PEC analytical modelling.

Electromagnetic induction disinfection applied to cemented knee arthroplasty implants: safety evaluation of potential changes in the bone cement.

Electromagnetic induction heating is a newly developed disinfection method aimed at improving periprosthetic infection outcomes after Debridement and Implant Retention (DAIR). One safety concern is its effect over polymethylmethacrylate (PMMA). The objective of this in-vitro study is to assess such effect on cement adjacent to metallic arthroplasty components. Two different PMMA products, with and without antibiotic, were applied on three total-knee arthroplasty implants. A portable device was used to administer induction-heating protocols: 70 °C, 3.5 min and 100 °C, 3.5 min, while the third prosthesis served as control. The 602 cm-1 and 558 cm-1 bands in Raman spectroscopy were used to assess isotactic and syndiotactic components of PMMA, while 1339 cm-1, 1295 cm-1 and 882 cm-1 bands in infrared spectroscopy (ATR-FTIR) were used to assess crystallinity. Isotactic/syndiotactic ratios were 0.27(±0.02) for antibiotic-free cement, and 0.41(±0.02) for gentamicin-loaded cement. After induction-heating protocols, isotactic fraction increased in antibiotic-free cement, and decreased in gentamicin-loaded cement. No evidence of crystallization was found in ATR-FTIR, except for a small increase in 1340 cm-1 band after 100 °C protocol. Spectroscopic techniques confirmed that PMMA only experienced minor structural changes after induction heating treatments. From a structural viewpoint, these results suggest that electromagnetic induction heating could be a safe disinfection technique for cemented implants in total knee arthroplasty.

Diffusion-prepared imaging with amplitude navigation for correction of motion-induced signal loss.

Diffusion-prepared imaging is a flexible alternative to conventional spin-echo diffusion-weighted EPI that allows selection of different imaging readouts and k-space traversals, and permits control of image contrast or image artifacts. We investigate a new signal model and reconstruction for diffusion-prepared imaging that addresses signal variations caused by motion-sensitizing diffusion gradients. A signal model, sampling theory, and reconstruction framework were developed assuming that motion-induced phases and the measured signals are random variables. The reconstruction incorporates real-valued amplitude weights estimated from low-resolution images into a linear system. A diffusion-prepared sequence was applied in phantom and in vivo acquisitions using different methods for managing phase errors from eddy currents or motion. This acquisition was performed with a high number of NEX and retrospectively undersampled to analyze errors in ADC estimation, and compared to spin-echo diffusion-weighted EPI, as well as conventional diffusion-prepared methods. The B1 sensitivity of the sequence was investigated using simulation and phantom experiments. Images reconstructed using the proposed method had similar image structures when compared to conventional spin-echo diffusion-weighted EPI, and demonstrated improved SNR efficiency compared to previous diffusion-prepared approaches. ADC errors followed a trend consistent with the derived signal model, sampling theory, and expected B1 sensitivity. The sampling requirement was shown to depend on the magnitude of motion-induced phases, as well as phases from residual eddy currents. Employing amplitude weights in the reconstruction of a diffusion-prepared sequence can improve SNR efficiency at the cost of a greater minimum sampling time and increased sensitivity to B1 inhomogeneity.

Electromagnetic Induction Sensor Design for Metal Oil Wear Particle Detection

When the mechanical equipment is working, the internal units interact with each other to produce different degrees of wear, wear will produce wear particles, the generated wear particles will flow around with the lubricating oil, if not timely detection and maintenance, it will aggravate the wear process, thus affecting the service life of the entire mechanical system. In this paper, a new high-precision three-coil electromagnetic induction sensor for metal oil wear in mechanical equipment is proposed, and Laval nozzle is innovarily applied to the oil inlet of the sensor. Firstly, based on the principle of electromagnetic induction, the physical characteristics of metal particles and their influence on magnetic field are analyzed, and the working principle and key parameters of the sensor are determined. Secondly, the overall structure of the sensor is designed, and the packaging and protection design are carried out according to the working condition. Finally, the coil schematic was established in Maxwell and boundary conditions and initial conditions consistent with the actual working conditions were set up for simulation verification under different types of wear particles at 1m/s. The results showed that the sensor's signal response was obvious under different particle sizes, which verified the rationality of the sensor design.

Eddy currents of a magnet falling through a copper pipe with slits

We present a theoretical model for the eddy currents induced by a cylindrical magnet falling through a copper pipe with vertical slits and the resulting inductive drag force. This system maintains the mathematically convenient cylindrical geometry of the classic intact pipe problem while introducing boundary conditions that result in fascinating eddy current patterns. Previous experiments have demonstrated that the inductive drag force is smaller in a slit pipe than in an intact pipe of the same radius, suggesting that the presence of slits reduces but does not eliminate the horizontal induced eddy currents required to produce a vertical drag force. Our theoretical model suggests that the horizontal eddy currents are reduced in slit pipes partly because the formation of a slit requires the removal of conducting material where eddy currents would otherwise have formed, and partly because the induced currents must flow purely vertically along the slit walls. We show that our theoretical model is consistent with our experimental data for the terminal velocities of magnets falling through copper pipes with different size slits and different numbers of slits. This experiment might serve as an advanced undergraduate laboratory activity.

Coupling CO2 capture process with electrochemically enhanced membrane distillation system for lithium-ion battery recovery: Reagent-Saving and environmental footprint reducing.

Coupling CO2 capture process with electrochemically enhanced membrane distillation system for lithium-ion battery recovery: Reagent-Saving and environmental footprint reducing.

The impact of the physical, electrical and magnetic properties of ferromagnetic materials on their excess loss

The impact of the physical, electrical and magnetic properties of ferromagnetic materials on their excess loss

Reducing axial temperature gradient in thick wall during local heat treatment of pressure vessels with electromagnetic induction

Abstract Post welding heat treatment (PWHT) is a key manufacturing procedure of thick-walled pressure vessel. Local PWHT is thereby needed due to large size of pressure vessels. Different from module furnace heating and resistance heating , electromagnetic induction heating is a new heating technology with the merits of green and high heating efficiency. However, the axial temperature gradient is inevitably generated. Excessive axial temperature gradient can reduce the effectiveness of heat treatment and even result in material scrap. In this paper, the electromagnetic-thermal multi-field coupling simulation was carried out on the thick-walled pressure vessel cylinder. The distribution of induced magnetic field, eddy current field and temperature field in the electromagnetic induction heating process was explored in detail. The influence of the number of cable turns, the width of outer wall insulation band, spaces between turns and the current frequency on the axial temperature gradient were explored. The parameters were optimized from the view of reducing axial temperature gradient. The optimized induction heating process parameters required by the cylinder were determined: 16 turns, 1460mm in outer insulation width, 32mm in spaces width and 2kHz current frequency.

Soil conductance classification for crop performance assessment using electromagnetic induction and geospatial techniques in coastal region of Indian Sundarbans

Soil conductance classification for crop performance assessment using electromagnetic induction and geospatial techniques in coastal region of Indian Sundarbans

Magnetic field induced by convective flow in Europa’s subsurface ocean

Magnetic field induced by convective flow in Europa’s subsurface ocean

A multi-channel MRI console for ultra-high field up to 14 T.

Ultra-high field magnetic resonance imaging (MRI) offers significant advantages in terms of signal-to-noise ratio and spatial resolution. In this study, we detail the development of a multi-channel home-built MRI console operating at 14T. We propose a hybrid analog-digital framework that shifts high-frequency radio frequency transmission and reception issues to lower frequencies, utilizing software-defined radio technology to process these low-frequency signals. Digital pre-emphasis is used in gradient calculations to counteract the effects of eddy currents during gradient switching. Our console can transmit and receive at center frequencies up to 600MHz. The pulse programmer module achieves a timing resolution of 20ns, while the transmitter can independently generate waveforms with varying amplitude, frequency, phase, and envelope. The receiver's dual-stage gain control provides 63 dB of adjustable range, optimizing the magnetic resonance (MR) signal's dynamic range. After frequency conversion, the MR signals are digitized with 16-bit resolution and 100MHz sampling rate. High-resolution water phantom images are acquired on the 14T Bruker Ascend 600 nuclear magnetic resonance magnet, demonstrating its potential for clinical research and application.