Induction Measurements Research Articles

Walking on snow-covered Arctic sea ice to infer ice thickness.

The ice-covered Arctic Ocean constitutes a unique underwater acoustic waveguide; it is a half-channel, upward refracting environment possessing a rough upper boundary consisting of sea ice of varying thickness. The sea ice itself is an acoustic waveguide, capable of supporting the propagation of compressional and shear waves. In particular, the ice supports compressional wave resonances created by impulsive forces on the upper surface of the ice. During ICEX20 and ICEX22, observations were made of compressional wave resonances excited by hammer drops, as well as by near-impulsive signals generated from the compression of dry snow underfoot while walking on the ice. Results demonstrate that ice thickness can be inferred from compressional wave resonances in the sea ice waveguide using signals generated by walking on the snow-covered ice. Inferred ice thickness estimates were consistent with observations made by magnetic induction and physical measurements in holes drilled through the ice. Average first- and multi-year ice thicknesses were inferred to be 1.1-1.3 m and 2.4-2.5 m, respectively.

INVESTIGATION OF THE HEMPEL PARADOX WITH CLASSES IN BIG DATA OF SOCIO-ECONOMIC SYSTEMS

The methods of self-learning and learning with an artificial intelligence teacher are being investigated. The research is carried out in the interests of solving the problems of countering money laundering and terrorist financing on incomplete, heterogeneous big data of socio-economic systems. The N-scheme of the Markov algorithm with a quantitative measure of induction is synthesized. A method is proposed for recording the number of relationships (interactions) of big data objects in the database of artificial intelligence. The theoretical provisions of Hempel’s paradox with classes are considered. The Hempel paradox is evaluated in heterogeneous big data. The Markov occurrence diagram for Hempel’s paradox with classes is synthesized. The Hempel paradox with classes is investigated under conditions of incompleteness and heterogeneity of the data sample. A method of inductive self-learning of artificial intelligence in the N-scheme of the Markov algorithm with a quantitative measure of induction is proposed. The method of using the associator m for training artificial intelligence in the N-scheme of the Markov algorithm is presented. A method of category, predetermined, inductive, teacher-directed self-study is proposed. It is concluded that self-learning methods have a limited potential for mathematical expressiveness. The reason for the low expressiveness is the inability to correctly operate with classes and categories, as well as the limitations of the possibility of logical predestination of truth, taking into account the heterogeneous, anthropogenic nature of objects and morphisms. The study of methods of teaching without a teacher revealed the scientific task of overcoming the Hempel paradox for classes of objects. It is indicated that the proposed method of categorically predetermined, inductive, teacher-directed self-learning actually shows that artificial intelligence a priori must be trained by a teacher, in other words, it cannot correctly self-study without it.

Measurement of inductive components impedance at low frequencies

The method of three voltmeters allows you to determine the components of the in-ductive impedance by measuring the voltages on the tested impedance, on the reference active resistance and at the output of the harmonic voltage source that feeds the meas-uring circuit. The analysis of the measuring circuit using the method of three voltmeters was carried out, mathematical expressions were found for calculating the active resistance and inductance as components of the investigated impedance based on the results of the measurement of three voltages. Regarding the values of the voltages on the investigated impedance, on the reference active resistance and on the output of the harmonic voltage source, there is a well-founded condition under which the obtained results will be valid. Using the method of three voltmeters, the frequency characteristics of the active resistance, inductance and Q-factor of the reference coil were experimentally determined in the range up to 100 kHz from a set of exemplary inductance measurements with previously known parameters. Experimental frequency dependences indicate the presence of a region of constant value of the impedance components at low frequencies. At frequencies higher than 30 kHz, there is a region of growth of the active component due to the influence of the proximity effect and skin effect and a region of apparent increase in inductance due to the influence of the distributed capacitance of the coil. The obtained characteristics make it possible to choose a frequency range in which the interfering influence of the distributed capacitance is minimal, as well as to determine the optimal frequency at which the Q-factor of the inductance is maximal. The relative error of inductance determination was no more than 0.3%, active resistance – 8.7%, Q factor – 5%.

Magnetic Forces by Permanent Magnets to Manipulate Magnetoresponsive Particles in Drug-Targeting Applications.

This study presents preliminary computational and experimental findings on two alternative permanent magnet configurations helpful for magnetic drug administration in vivo. A numerical simulation and a direct experimental measurement of the magnetic induction on the magnet system's surface were used to map the magnetic field. In addition, the ferrite-type (grade Y35) and permanent neodymium magnets (grade N52) to produce powerful magnetic forces were also examined analytically and quantitatively. Ansys-Maxwell software and Finite Element Method Magnetism (FEMM) version 4.2 were used for all numerical computations in the current investigation. For both magnets, the generated magnetic fields were comparatively studied for targeting Fe particles having a diameter of 6 μm. The following findings were drawn from the present investigation: (i) the particle deposition on the vessel wall is greatly influenced by the intensity of the magnetic field, the magnet type, the magnet size, and the magnetic characteristics of the micro-sized magnetic particles (MSMPs); (ii) ferrite-type magnets might be employed to deliver magnetoresponsive particles to a target location, even if they are less powerful than neodymium magnets; and (iii) the results from the Computational Fluid Dynamics( CFD) models agree well with the measured magnetic field induction, magnetic field strength, and their fluctuation with the distance from the magnet surface.

In situ estimation of soil hydraulic and hydrodispersive properties by inversion of electromagnetic induction measurements and soil hydrological modeling

Abstract. Soil hydraulic and hydrodispersive properties are necessary for modeling water and solute fluxes in agricultural and environmental systems. Despite the major efforts in developing methods (e.g., laboratory-based, pedotransfer functions), their characterization at applicative scales remains an imperative requirement. Accordingly, this paper proposes a noninvasive in situ method integrating electromagnetic induction (EMI) and hydrological modeling to estimate soil hydraulic and transport properties at the plot scale. To this end, we carried out two sequential water infiltration and solute transport experiments and conducted time-lapse EMI surveys using a CMD Mini-Explorer to examine how well this methodology can be used to (i) monitor water content dynamic after irrigation and to estimate the soil hydraulic van Genuchten–Mualem parameters from the water infiltration experiment as well as (ii) to monitor solute concentration and to estimate solute dispersivity from the solute transport experiment. We then compared the results with those estimated by direct time domain reflectometry (TDR) and tensiometer probe measurements. The EMI significantly underestimated the water content distribution observed by TDR, but the water content evolved similarly over time. This introduced two main effects on soil hydraulic properties obtained by the two methods: (i) similar water retention curve shapes, but underestimated saturated water content from the EMI method, resulting in a scaled water retention curve when compared with the TDR method; the EMI-based water retention curve can be scaled by measuring the actual saturated water content at the end of the experiment with TDR probes or by weighing soil samples; (ii) almost overlapping hydraulic conductivity curves, as expected when considering that the shape of the hydraulic conductivity curve primarily reflects changes in water content over time. Nevertheless, EMI-based estimations of soil hydraulic properties and transport properties were found to be fairly accurate in comparison with those obtained from direct TDR measurements and tensiometer probe measurements.

Contactless Measurement of Current and Mutual Inductance in Wireless Power Transfer System Based on Sandwich Structure

The mutual inductance between the transmitter and receiver sides is critical for the efficiency of a wireless power transfer (WPT) system. This article proposes a novel online mutual inductance measurement method based on a local detection coil with a sandwich structure. The mutual inductance and the receiver current are obtained by measuring the induced voltage of the sandwich coil and the output voltage of the inverter, with contactless measurement from the receiver side. Using the ferrite substrate as the skeleton of the sandwich detection coil not only increases the differential mutual inductance between the receiver coil and the sandwich coil but also maintains the differential mutual inductance almost constant when horizontal misalignment occurs. Moreover, the differential mutual inductance is used to calculate the mutual inductance between the transmitter and receiver coils and the orthogonal eigenvalue expansion method is exploited to analyze the sandwich detection coil in a finite region. Then, the factors affecting the differential mutual inductance are analyzed and optimized, and a stable differential mutual inductance is obtained by formulating a standard coil design procedure. Finally, a prototype is built to verify the proposed method. The experimental results show that the differential mutual inductance remains almost constant when the horizontal misalignment reaches 50% of the outer radius of the transmitter/receiver coil, and the maximum calculated error of the detected mutual inductance is 2.18%.

Time-resolved velocity and ion sound speed measurements from simultaneous bow shock imaging and inductive probe measurements.

We present a technique to measure the time-resolved velocity and ion sound speed in magnetized, supersonic high-energy-density plasmas. We place an inductive ("b-dot") probe in a supersonic pulsed-power-driven plasma flow and measure the magnetic field advected by the plasma. As the magnetic Reynolds number is large (RM > 10), the plasma flow advects a magnetic field proportional to the current at the load. This enables us to estimate the flow velocity as a function of time from the delay between the current at the load and the signal at the probe. The supersonic flow also generates a hydrodynamic bow shock around the probe, the structure of which depends on the upstream sonic Mach number. By imaging the shock around the probe with a Mach-Zehnder interferometer, we determine the upstream Mach number from the shock Mach angle, which we then use to determine the ion sound speed from the known upstream velocity. We use the sound speed to infer the value of Z̄Te, where Z̄ is the average ionization and Te is the electron temperature. We use this diagnostic to measure the time-resolved velocity and sound speed of a supersonic (MS ∼ 8), super-Alfvénic (MA ∼ 2) aluminum plasma generated during the ablation stage of an exploding wire array on the Magpie generator (1.4 MA, 250ns). The velocity and Z̄Te measurements agree well with the optical Thompson scattering measurements reported in the literature and with 3D resistive magnetohydrodynamic simulations in GORGON.

Self-rollable Polymer Stent Integrated with Wireless Pressure Sensor for Real-time Monitoring of Cardiovascular Pressure

In this paper, we propose a self-rollable polymer (SU-8) stent integrated with a passive LC pressure sensor for the uninterrupted monitoring of cardiovascular pressure. The design of the LC pressure sensor and polymer stent was optimized by varying the turns of inductor and the stent thickness. A wireless pressure sensor with 30 turns of coils was selected based on the experimental results of inductance and radial force measurements. The sensor was fabricated simultaneously with a stent structure with a thickness of 40 µm on a two-dimensional plane using conventional micromachining processes. The fabricated smart stent was placed inside a silicon tube, and its performance was evaluated as a function of working distance (0–11 mm), working pressure (0–100 mmHg), and different media (air, DI water, and saline). After the preliminary experiment, the entire stent device was encapsulated with a thin parylene C layer, and improvements in biocompatibility were confirmed using a viability test with human umbilical vein endothelial cells. The proposed smart stent is expected be widely used in medical applications owing to its structural excellence.

Diagnosing Disk-Space Variation in Transformer Windings Using High-Frequency Inductance Measurement

Leakage and magnetizing inductances of transformer windings are routinely measured by power utilities during scheduled maintenance. They are often used to confirm the diagnosis of mechanical damages in windings after Swept Frequency Response Analysis shows a mismatch. Inductance measurements performed at power frequency can possibly reveal the presence of damages that have substantially progressed but cannot detect them at their nascent stages since inductances at power frequency remain almost unaltered. This paper investigates the possibility of using high-frequency inductance to this end considering a frequently encountered mechanical damage, viz., disk-space variation in a disk winding. Effect of disk-space variation is investigated in this article using FEM at first and inductances at different frequencies are considered: magnetizing and leakage inductances at 50 Hz, and inductance at a higher frequency region corresponding to winding resonances, say, 500 kHz. The inductance at high frequencies not only exhibited increased sensitivity compared to that at power frequency, but also captured the extent of damage. Simulations performed using Ansys Maxwell and experimental results on an actual 1- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\phi$</tex-math></inline-formula> transformer are reported. Results show that the high-frequency inductance not only offers a considerably increased sensitivity to disk-space variation in windings compared to the power frequency inductances, but also provides insight regarding the extent of movement which is not apparent from the frequency response.

Variability of coil inductance measurements inside an interleaving structure

The present article is a continuation of our previous works on the anomalies in the decay rates and the capacitance measurements inside a modified Faraday cage. Here we present the anomalous variations in the measurements of inductance when a coil is placed inside an interleaving structure of metal and organic material. The fluctuation in the inductance values was found to be in the range − 0.007 to 0.018 mH. Additionally, it was observed that the temperature coefficient which was 0.0062 mH/°C initially jumped to two distinct levels, 0.0095 mH/°C and 0.0145 mH/°C, respectively. A multiple factor analysis of our results revealed a very strong correlation (R2 = 95.2%) between the inductance and the combination of the temperature and the relative humidity both measured inside the cage, next to the inductor.

Modelling a dynamic magneto-agglutination bioassay

The process of developing an end-to-end model of a magneto-immunoassay is described, simulating the agglutination effect due to the specific binding of bacteria to paramagnetic particles. After establishing the properties of the dose-specific agglutination through direct imaging, a microfluidic assay was used to demonstrate changes in the magnetophoretic transport dynamics of agglutinated clusters via transient inductive magentometer measurements. End-to-end mathematical modelling is used to establish the physical processes underlying the assay. First, a modified form of Becker–Döring nucleation kinetic equations is used to establish a relationship between analyte dose and average cluster size. Next, Stokes flow equations are used to establish a relationship between cluster size and speed of motion within the fluid chamber. This predicts a cluster-size dynamic profile of concentration of PMPs versus time when the magnetic field is switched between the two actuated magnets. Finally, inductive modelling is carried out to predict the response of the magnetometer circuit in response to the dynamics of magnetic clusters. The predictions of this model are shown to agree well with the results of experiments, and to predict the shape of the dose-response curve.

Elevated and Sustained Intracellular Calcium Signalling Is Necessary for Efficacious Induction of the Human Sperm Acrosome Reaction.

Progesterone and prostaglandin E1 are postulated to trigger the human sperm acrosome reaction (AR). However, their reported efficacy is very variable which likely, in part, reflects the plethora of experimental conditions and methodologies used to detect this physiologically relevant event. The purpose of this study was to develop an assay for the robust induction and objective measurement of the complete AR. Sperm from healthy volunteers or patients undertaking IVF were treated with a variety of ligands (progesterone, prostaglandin E1 or NH4Cl, alone or in combinations). AR, motility and intracellular calcium measurements were measured using flow cytometry, computer-assisted sperm analysis (CASA) and fluorimetry, respectively. The AR was significantly increased by the simultaneous application of progesterone, prostaglandin E1 and NH4Cl, following an elevated and sustained intracellular calcium concentration. However, we observed notable inter- and intra-donor sample heterogeneity of the AR induction. When studying the patient samples, we found no relationship between the IVF fertilization rate and the AR. We conclude that progesterone and prostaglandin E1 alone do not significantly increase the percentage of live acrosome-reacted sperm. This assay has utility for drug discovery and sperm toxicology studies but is not predictive for IVF success.

Superconducting boron doped nanocrystalline diamond microwave coplanar resonator

A coplanar waveguide resonator (CPR) is presented for kinetic inductance (Lk) and penetration depth (λL) measurements of superconducting boron doped nanocrystalline diamond (B-NCD) at microwave frequencies of 0.4 to 1.2 GHz and at temperatures below 3 K. Using finite element modelling and experimental measurements, this work demonstrates that thin granular B-NCD films (thickness d≈ 500nm) on Si have a large penetration depth (λL≈3.8μm), and therefore an associated high kinetic inductance per square (Lk,□≈ 670 to 690 pH/□). These values are much larger than those typically obtained for films on single crystal diamond, which is likely due to the high granularity of the nanocrystalline films. Based on the measured Q factors of the structure, the calculated surface resistance is found to be around ≈ 1 to 6μΩ at T<2 K in the 0.4 to 1.2 GHz range, demonstrating the potential for granular B-NCD for high quality factor superconducting microwave resonators and highly sensitive kinetic inductance detectors.

Magnetic and Electromechanical Characterization of a High-JC RRP Wire for the HL-LHC MQXF Cable

In this work, we summarize the results of a series of inductive and transport measurements aimed at the evaluation of the electromechanical performance of a 0.85 mm diameter RRP wire procured for the HL-LHC project. The critical current dependence on the magnetic field and uniaxial applied strain (between −0.2 and 0.5%) has been investigated in a temperature range between 4.5 K and 10 K. Furthermore, the wire magnetization up to 12 T has been measured at different temperatures (4.3 K–14 K) to determine the wire's effective filament diameter and to complement the critical current density in the temperature and field range where transport current measurements were not available. The experimental results have been analysed in the framework of the Extrapolative Scaling Expression, by using a multi-step approach for the data fitting. These results provide an accurate parameterization of the critical surface in terms of field, temperature and strain, and can be used as a general reference for magnet design.

DC Characterization of a Low-Field Nb3Sn Prototype Conductor for a DEMO TF Coil

A Low Field W&R (Wind and React) conductor, developed in the frame of the conceptual design studies for the Toroidal Field (TF) coils of DEMO, has been designed to be constituted of a small number of superconducting Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn strands and a high number of stabilization copper wires. It has been extensively characterized at the SULTAN facility at Swiss Plasma Center (SPC) in February 2021. The conductor has been operated up to its target current, 70.8 kA, and characterized up to a background magnetic field of 10.78 T. The test program included AC loss measurements, current sharing temperature ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T_cs</i> ) and critical current ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I_c</i> ) measurements before and after cyclic loading. Critical temperature ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T_c</i> ) measurements were performed on the virgin conductor at the beginning and at the end of the test campaign. In this work we are focusing on the DC characterization, while the AC measurements analysis will be the object of a following work. Concerning DC tests, premature quench phenomena prevented from operating the conductor at the target current – field conditions. Nevertheless, at lower currents <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T_cs</i> stability was observed, with no performance degradation due to cycling. The present paper investigates these results and tries to give an explanation through measurements and tomographic analysis. Furthermore, the achieved strain distribution in the conductor, obtained by means of inductive measurements analysis, will be shown. The implications of the design approach on the performance, based on the outcome of such tests, are discussed.

Object Composition Identification by Measurement of Local Radio Frequency Magnetic Fields with an Atomic Magnetometer

Proof of principle of object composition identification based on inductive measurements with an atomic magnetometer has been demonstrated in highly engineered laboratory conditions. Progress in the development of portable miniaturised magnetometers has encouraged on the parallel development of the measurement technologies involving this sensor, in particular concepts that would enable operation in complex test scenarios. Here, we explore the problem of material identification in the context of measurements performed with variable distance between the object and the primary radio-frequency field source and sensor. We identify various aspects of the measurement affected by variable distance and discuss possible solutions, based on the signal phase analysis, a combination of frequency and angular signal dependencies and the implementation of a pair of excitation coils.

Magnetic Permeability Sensor Array Prototype to Evaluate Reservoir Phase Permeability in situ Downhole

A measurement system capable of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in situ</i> measurements of formation permeability is described. The measurement method relies upon imaging the distribution of magnetic permeability fluid injected into a wellbore system through mutual inductance measurements between pairs of coils and relating the change in distribution of this fluid over time to a direct measurement of formation phase permeability. Analysis of the mutual inductance measurement method shows a unique response to distributions of magnetic permeability for various coil spacings and insensitivity to other confounding electrical parameters. The lower bound of measurement variance for this system is modeled for a continuum of coil spacings and radii of investigation for a perturbation in magnetic permeability.

Micro magnet location using spin waves

In this work, we present experimental data demonstrating the feasibility of magnetic object location using spin waves. The test structure includes a Y3Fe2(FeO4)3 film with four micro-antennas placed on the edges. A constant in-plane bias magnetic field is provided by the NdFeB permanent magnet. Two antennas are used for spin wave excitation, while the other two are used for the inductive voltage measurement. There are nine selected places for the micro magnet on the top of the film. The micro magnet was subsequently placed in all nine positions and spin wave transmission and reflection were measured. The obtained experimental data show the difference in the output signal amplitude depending on the micro magnet position. All nine locations can be identified by the frequency and the amplitude of the absolute minimum in the output power. All experiments are accomplished at room temperature. Potentially, spin waves can be utilized for remote magnetic bit readout. The disadvantages and physical constraints of this approach are also discussed.

THE INFLUENCE OF ANNEALING TEMPERATURE ON THE MAGNETIC PROPERTIES OF CRYO-ROLLED NON-ORIENTED ELECTRICAL STEEL

The paper is focused on a comparison of the magnetic properties of the non-oriented isotropic electrical steel containing 3.5% Si. The material was processed by conventional ambient temperature rolling and progressive rolling at the cryogenic conditions at liquid nitrogen. Deformations of the samples in both thermal conditions were in the interval εÎ&lt;5;35&gt;[%]. Subsequently, the samples were heat treated at temperatures TÎ&lt;900;1100&gt; [°C]. Measuring of the magnetic properties was carried out in an alternating magnetic field at frequencies f= 50; 100; 150 Hz. At a frequency of 50 Hz were achieved smallest magnetic losses and therefore further measurements were made at a given frequency. Followed measurements of the magnetic induction were conducted at different intensities of the magnetic field. EBSD analyses were performed to obtain the IPF maps on which the resulting structure was evaluated after processing of the material. The specific magnetic losses were compared to different processing methods. The best magnetic properties defined as by minimal values of core loses were reached after samples rolled at cryogenic temperature followed by subsequently annealed. Also, higher proportion of cubic texture was archived after rolling at cryogenic temperature with compared to samples processed at ambient temperature.

Euler–Lagrange method for low-frequency metamaterials

PurposeThe purpose of this paper is to develop a modeling method for the analysis of low-frequency metamaterials (MTMs) and their near-field applications.Design/methodology/approachThe Euler–Lagrange method is introduced. An MTM is modeled as a multi-degree-of-freedom system without homogenization. The properties and the responses of the MTM in a near-field device are readily and rigorously studied through the motion equation derived from the Lagrange equations. The resonance frequencies and the corresponding resonance modes are solved from the characteristic equation.FindingsThe numerical results of the proposed method show good agreement with the experimental ones. A measurement of MTM-core coil resistance and inductance shows high accuracy of the proposed method.Originality/valueThe proposed Euler–Lagrange method provides a new study perspective and enables more flexible, rigorous and straightforward analysis of low-frequency MTMs in near-field applications. Consequently, the presented work greatly facilitates further explorations and studies on various novel MTM-based low-frequency near-field devices and systems.