Ferromagnetic Rods Research Articles

Localization of a Crack in Moving Cylindrical Ferromagnetic Rods by Measuring the Fourier Coefficients of the Leakage Magnetic Flux

Localization of a Crack in Moving Cylindrical Ferromagnetic Rods by Measuring the Fourier Coefficients of the Leakage Magnetic Flux

Development and experimental validation of conceptual models for solenoid-based in-vessel two-channel control rod position indicator

In this study, we proposed in-vessel two-channel control rod positioner models for small nuclear reactors and carried out performance tests to evaluate applicability of the models. Embedding control rod positioners in reactors reduces the volume of small reactors and minimizes the penetration parts of reactor. In this study, two models having two physically separated solenoids were developed for measuring the position of the control rod by using the inductance change of a solenoid. First, the principle of measuring the position of a ferromagnetic rod by using a solenoid was formulated, and the change in solenoid inductance with the rod position was calculated through finite element analysis. Based on the proposed models, test products were manufactured and tested on three items to confirm the feasibility of the proposed solenoid-based two-channel control rod position indicator.

Electromagnetic Mill-Promoted Palladium-Catalyzed Heck-Type Cyclization/Decarboxylative Coupling of (Z)-1-Iodo-1,6-diene with Propiolic Acids.

Electromagnetic mill (EMM)-promoted solid-state cascade Heck-type cyclization/decarboxylative coupling of propiolic acid with (Z)-1-iodo-1,6-diene derivate was demonstrated. The reaction was realized via palladium catalysis, which is solvent-free and involves no additional heating. The collision between ferromagnetic rods could not only be a favor to the mixing between the solid substrates and the catalyst system, but also the thermogenic action could accelerate this transformation. More importantly, this EMM strategy realized multiple bond construction under mechanochemical conditions in one pot.

Circumferential Localization of a Crack in Cylindrical Ferromagnetic Rods Based on the Fourier Coefficients of the Radial Directional Magnetic Flux Leakage

In this paper, we present a novel magnetic flux leakage method to estimate the circumferential position of a crack in cylindrical ferromagnetic rods by modelling the crack as a magnetic dipole. The first-order Fourier coefficients of the radial component of the magnetic flux leakage are measured using two coils with widths proportional to | cos ϕ| and | sin ϕ|, where ϕ is the circumferential location of the rod surface. The circumferential and axial location of a crack is estimated using only two sensors, as demonstrated for an S45C cylindrical rod.

Narushenie kiral'noy simmetrii i neodnorodnye sostoyaniya v deformirovannykh ferromagnetikakh

The general form of chiral terms associated with deformation of a ferromagnet is determined. The possibility of a transition from the helical state to the vortex state is demonstrated for a ferromagnetic rod subjected to elastic torsional strain. In the case of a single screw dislocation, the formation of the skyrmion state due to elastic strains and the helical distribution of magnetization induced by strains in the dislocation core is indicated. The conditions in which a transition from one chiral magnetization distribution to another distribution in an ensemble of identical dislocations are determined.

Eddy Current Testing Methods and Design for Pipeline Inspection System: A Review

Non-destructive testing and complex systems integration are commonly used in transportation, aircraft, automotive, manufacturing, petrochemical, and defence. Eddy current testing (ECT) is a common non-destructive evaluation technique, especially in the coating, nuclear, and oil and gas industries. However, the eddy current testing method must continue to focus on the probe’s construction and application. It ascribed noisy data to inadequate detection and a severe false alarm problem. Nonetheless, only few academics have elaborated on the intelligent ECT crack detection method. This study provides an overview of the eddy current testing technique and the probe structure design elements that influence fracture detection accuracy. The first section describes the Eddy current testing by encircling coil system for a differential probe (ECDP) and an encircling coil for an absolute probe design (ECDP). The explanations focus mostly on the probe’s creation and detection in Rotating electromagnetic field eddy current (RoFEC). The advantages and disadvantages of eddy current testing surrounding probes are analysed. In addition, a summary of prior studies investigating testing samples of ferromagnetic pipe, steel rod, and wire rope is presented. The second segment focuses on Eddy current testing employing a Giant Magnetoresistance (GMR) sensor system, with a particular emphasis on sensor arrays, GMR, and conventional eddy current coils for crack identification. Finally, a comprehensive overview of eddy current testing methods and design for non-destructive pipeline inspection systems is presented.

THE MAGNETIC CHAIN MATHEMATICAL MODELS OF A NEW ANGULAR DISPLACEMENT CONVERTER WITH A VARIABLE ACTIVE AREA OF A MOVABLE CORE

The article develops mathematical models of the magnetic chain of new differential type angular displacement transformer converter with a variable active area of the movable core, in which the width of the movable ferromagnetic core is a function of the angular displacement of the converter. In this case, the magnetic chain of the converter, divided into three characteristic (before the mobile ferromagnetic core, ferromagnetic core and after the ferromagnetic core) sections, is considered as a magnetic chain with distributed parameters. It is established that when the magnetic resistance of the magnetic chain steel part is not taken into account, the working magnetic flux is a linear function of the angular displacement of the movable ferromagnetic core of the converter. The obtained mathematical models of the magnetic chain of the transformer converter of angular displacements in the form of analytical expressions of the magnetic flux in long ferromagnetic rods and the magnetic voltage between them for three characteristic sections allow to take into account the distribution of the parameters of the magnetic resistance of long ferromagnetic rods and the magnetic capacity of the air gap between them, as well as the magnetic capacity of the air gap between the rods and the movable ferromagnetic core.

Magnetostriction Generator as Acoustic Wave Generator for Underwater Applications

At this time the research related to the effect of magnetostriction for underwater applications is still limited. Acoustic or sound waves are more easily propagated underwater than electromagnetic waves or light. An acoustic wave or sound can be generated by utilizing the magnetostriction effect, where this effect occurs when a rod of ferromagnetic material such as iron or nickel is magnetized and interacts with another magnetic field, resulting in vibration of the metal rod. This research aims to design and realize a magnetostriction generator as an acoustic wave generator at a frequency of 1 to 10 kHz for underwater applications, consisting of: a tuned LC oscillator circuit, and a ferromagnetic metal rod which is magnetized using a dc voltage. The results of measurements and testing of the magnetostriction generator show: (1) if it is equipped with a membrane, can work to emit an acoustic wave or sound at a frequency of ± 8.62 kHz in the air up to a distance of 15 cm without distortion with an average amplitude decrease of ± 0.648 dB for each the distance increased by 1 cm, and (2) if equipped with a membrane and enclosed in a waterproof casing, capable of transmitting the acoustic waves at a frequency of ± 8.31 kHz underwater up to a distance of 7 cm without distortion with an average amplitude decrease of ± 4.217 dB for each the distance up 1 cm. Overall the magnetostriction generator designed can work to generate and transmit the acoustic waves or sound underwater, as expected.

Vibration sensor for monitoring systems of construction elements of high-voltage power lines

PURPOSE. To develop a differential parametric inductive transducer of vibration values into an electrical signal, which is a vibration displacement sensor (DV) with a new principle of operation. Theoretically substantiate the performance of the proposed DV. To develop a new system for vibroacoustic monitoring of the technical condition of overhead power transmission line (TL) supports using the proposed DV. METHODS. When solving this goal, the theory of parametric transducers and the main provisions of the theory of vibration diagnostics were used. RESULTS. The design feature of the developed DV is the absence of an excitation coil, and its functional elements form a full-fledged measuring bridge, the arms of which include interturn capacitances of the windings of the first and second measuring coils, as well as capacitances formed by a metal cylindrical electrode with a coaxially located inside it ferromagnetic rod and the first lower rows of wire windings of the measuring coils. The bridge circuit operates in a resonant mode, which ensures the high sensitivity of the proposed sensor, and the quadrature conversion of the information signal provides the necessary level of noise immunity. The received signal is a functional dependence of the output voltage of the measuring bridge on the magnitude of external vibrations, the characteristics of the temporary realizations of which reflect the degradation processes occurring in the power transmission line supports. CONCLUSION. The proposed system for monitoring the integrity of power transmission line supports is actually a distributed real-time sensor network that implements PLC technology. The DV of each sensor module registers microvibrations of the structural elements of the corresponding power transmission line support, caused by natural disturbing factors during their operation, and converts them into an electrical information signal, which forms the basis of monitoring information about the current state of the power transmission line support structural elements.

Dirac cones and valley topological states of classical spin waves in artificial magnonic crystals with two-dimensional honeycomb lattice

A model of artificial magnonic crystals (AMCs) with a two-dimensional honeycomb lattice of cylindrical ferromagnetic rods embedded in another ferromagnetic material is proposed. Topological properties including Dirac cones, Dirac-like point and valley states of classical spin waves in the above AMCs are theoretically investigated by numerically solving the Landau-Lifshitz equation. It is shown that Dirac cones and valley states at the boundary of the first Brillouin zone can be generated in the dispersion relation. Furthermore, Dirac-like point can also be obtained at the center of the first Brillouin zone due to the accidental degeneracy of the magnonic bands. These discoveries of Dirac cones, Dirac-like point and valley topological states in artificial magnonic crystals not only open a new field in topological condensed matter, but also provide a novel platform for fabricating topological classical spin-wave devices.

Residual Stress Distribution Monitoring and Rehabilitation in Ferromagnetic Steel Rods.

Different means of residual stress distribution monitoring in magnetic rods are illustrated in this paper, through measurements of permeability, magnetoelastic uniformity using two different setups, sound velocity, and eddy currents. The effectiveness of these techniques was assessed through the stress monitoring of the same magnetic rod, suffering residual stresses in two known volumes caused by controlled hammering. Furthermore, rehabilitation has been achieved by means of stress annihilation, achieved by localized induction heating. As a result, the magnetoelastic and sound velocity uniformity measurements are more appropriate for the monitoring of localized residual stresses, while eddy current measurements are useful for the monitoring of the geometrical deformation.

Effects of the magnetic field on the viscoelastic wave propagation and dynamic material properties

In this paper, the longitudinal wave propagation of a thin ferromagnetic (Fe-Cr-Al alloy) rod under the transverse magnetic field is investigated analytically without ignoring the viscoelastic characteristics of this alloy. The analysis is based on the Bernoulli-Euler rod theory and a 4-element viscoelastic model based on the experimental observation. The viscoelastic wave characteristics and the behaviours of dynamic material properties under the magnetic field are investigated. The analytically results show that the longitudinal wave propagation and the dynamic material properties of the rod are affected by the magnetic field existence (for magnetic field magnitude values greater than about 107A/m), except the imaginary part of the complex elasticity modulus. Furthermore, in a large frequency range, depending on the ratio of the group velocity to the phase velocity an abnormal dispersion characteristic is observed.

Fractional derivative resolution of the anomalous magnetic field diffusion through a ferromagnetic steel rod: Application to eddy current testing

Electromagnetic evaluations are performed daily by steel manufacturers and steel user companies. Among different methods, Eddy Current Testing (ECT) is routinely used. It is versatile, simple, and conveys rich information. ECT evaluations on steel specimens remain complex to interpret quantitatively. Most steels are ferromagnetic and exhibit high nonlinear magnetic behaviors. Such nonlinearities are an issue when it comes to signal analysis and interpretation. The magnetic field diffusion in a steel rod is highly frequency-dependent. It is the direct consequence of the Eddy current generation. If the rod is ferromagnetic, the unstable distribution of the magnetic domains interacts with the macroscopic Eddy current circulation and perturbs the magnetic field diffusion, which becomes anomalous. Fractional derivative diffusion equations are appropriate tools for the simulation of these phenomena. The fractional order acts as an adjustment parameter that provides flexibility in the simulation method. In this study, a 2D fractional diffusion equation has been solved by using finite differences in polar coordinates to anticipate the magnetic field diffusion and the ECT measurement in a steel rod specimen. Defects have been simulated through local variations of the physical properties. Good simulation results have been obtained and validate the fractional diffusion equation as an efficient method for the simulation of the anomalous diffusion magnetic field and the interpretation of ECT measurements.

ФЕРРОЗОНДОВЫЕ МАГНИТОМЕТРЫ С НОВЫМ СПОСОБОМ ВОЗБУЖДЕНИЯ НА ОСНОВЕ МАГНИТОЭЛЕКТРИЧЕСКОГО ВЗАИМОДЕЙСТВИЯ

The analysis of the functional peculiarities of the known flux gates has shown that the constructive and technological methods used to increase their operational characteristics within the framework of traditional so-lutions have basically exhausted themselves. The paper proposes a method for exciting flux gates based on a new physical principle relying on the effect of magnetoelectric interaction. The possibility of obtaining a magnetoelectric effect in local inhomogeneities of solid-state structures of ferrite elements of flux-gates when exposed to an alternating electric field is analyzed and substantiated. In this case, in the entire volume of the fer-romagnetic core at the same frequencies of electromechanical and magnetic resonances, a modulating physical process is excited in the form of a standing magnetoelectric wave. This creates a corresponding magnetic modu-lation structure in the entire volume of the ferromagnetic system of the flux gate. The considered design of a fluxgate modulator implements a new method of exciting flux gates, containing a ferromagnetic rod system in the form of two ferrite rod half-elements, located coaxially and joined together by a ferrite permanent magnet with magnetization along the axis of the rods. The authors have experimentally studies a new method for exci¬ting flux gates. The proposed method for exciting flux gates opens up wide opportunities for research in a new direction in science – spintronics, in particular, the applied use of magnetoelectric interaction, which can be effectively used to create various options for flux gates based on new physical principles of operation.

Особенность намагничивания ферромагнетика переменным полем

It has been experimentally established that the demagnetizing field of the magnetic poles formed at the ends of an open ferromagnetic cylinder decreases with increasing frequency of the magnetizing field due to a decrease in their size under the influence of the surface effect. For this reason, as the frequency of the magnetizing external field increases, the internal field in a ferromagnetic cylinder near the surface approaches it in amplitude. In addition, it has been found that the field on the surface of a ferromagnetic rod magnetized by an alternating field significantly exceeds the latter in strength with increasing frequency of this field.

Magnetic Field Scattering of a Transformer Winding on a Round Rod for a Safety Relay

A model permitting simulation of the magnetic field scattering of a current-bearing winding on a round ferromagnetic rod is developed. The model is verified experimentally.

Modeling of magnetic fields of scattering of transformer windings on a round rod for relay protection

A mathematical model is developed that allows with sufficient accuracy to simulate the magnetic field scattering of the coil and the current windings located on a round ferromagnetic rod. Correctness of the calculation is verified by experimental data. Keywords winding, transformer, relay protection, magnetic field, scattering, modeling. novozhilova_on@mail.ru

Dispersion of magnetic susceptibility in a suspension of flexible ferromagnetic rods

The properties of suspensions of magnetosomes extracted from magnetotactic bacteria are investigated. By using dynamic light scattering and measuring the dispersion of magnetic susceptibility it is shown that sonicated samples with broken magnetosome chains have qualitatively different behavior in comparison with native samples. This is explained by the presence of flexible chains of magnetosomes in non-sonicated samples which have the qualitative features of magnetic susceptibility predicted by the model of flexible magnetic rods. • The model of flexible magnetic rods of magnetic susceptibility is proposed. • Broken magnetosome chains have qualitatively different behavior as native samples. • Frequency dependence of magnetosomes' complex susceptibility is analyzed.

Express Diagnostic Method of the Stress State of Weakly Magnetized Ferromagnetic Rods

A method for express diagnostics of weakly magnetized ferromagnetic rods is proposed. It is based on measuring the stray magnetic field of the rod. We analyze the inverse magnetostatic problem and formulate the conditions when its regularization is possible. In this case, it is possible to connect the value of the average transverse component of magnetization with the results of the measured stray magnetic field. The distributions of transverse magnetization values were experimentally studied using rods made of SV08G2S [transliterated from Russian] and ER-308LSi steels as an example. The studied samples were subjected to impact plastic deformation, tensile deformation, and torsion deformation. It is shown that this method allows to register areas with stress concentrations without additional magnetization of the test sample. A feature of the method is the use of once calculated system functions without solving large systems of equations and using unstable spectral methods. The method is applicable for cylindrical objects of small radius far from the edge of the test sample, when the magnetization in the cross section of the sample can be considered as constant.

3:27 PM Abstract No. 221 Multicenter preliminary experience with percutaneous ultrasound gastrostomy: do interventional radiologists need fluoroscopy for gastrostomy placement?

To evaluate the initial feasibility and safety of percutaneous ultrasound gastrostomy (PUG) using the novel technique of magnetic gastropexy by interventional radiologists at two institutions. Institutional review board approval was obtained at both institutions, and all attempted PUG procedures were retrospectively reviewed. Data collected included BMI, procedural details, time to initiate feeds, and complications. Briefly, the stomach is coapted to the abdominal wall using an external high field magnet and orogastric tube with a ferromagnetic rod within an inflatable balloon. Direct ultrasound guidance is used to puncture the balloon and the balloon is used as a snare for a pigtail wire. A push technique self-dilating gastrostomy tube is then placed over the wire. Twenty patients underwent attempt at PUG. Patient demographics included a mean age of 67.3 ± 12 years and BMI of 24.0 ± 3.3 kg/m2. Most procedures were done with moderate sedation (17/20). Technically successful placement of PUG was achieved in 75% of patients (15/20), including one case performed completely at the bedside without fluoroscopy. Fluoroscopy was used for confirmation or assistance in placement during all other cases (median fluoro time, 1.5 ± 4.1 min). Three patients required adjunctive techniques for PUG placement. One patient with a gastroesophageal stricture required conversion to fluoroscopically guided gastrostomy tube placement. One major and one minor complication related to tube placement occurred. Additionally, one patient was admitted with aspiration pneumonia 16 days post procedure. Tube feeds were initiated in less than 24 hours in 16 patients. Percutaneous ultrasound gastrostomy (PUG) using a proprietary external magnet for coaptation gastropexy is a safe technique for gastrostomy placement, allowing prompt initiation of supplemental nutrition. This study demonstrates that as with all interventional radiology procedures, appropriate patient selection is critical. With continued experience and refinement of technique, fluoroscopy will not be required as was demonstrated with the successful bedside gastrostomy.