Nonlinear Magnetic Properties Research Articles

The Magnetic Properties of Fluorenyl and tert-Butyl-nitroxyl Acene-Based Derivatives: A Quantum Chemical Insight

Acenes, as a class of polycyclic aromatic hydrocarbons, attract considerable attention due to their remarkable nonlinear optical and magnetic properties. The aim of this work was the elucidation of the capability of radical-substituted acene derivatives to undergo spin-state-switching rearrangements. For this purpose, a series of acene-based (anthracene, pentacene, heptacene) molecules bearing fluorenyl and tert-butyl-nitroxyl radicals were investigated through comprehensive quantum chemical modeling of their electronic structures, isomerization and magnetic properties. A possible mechanism of the transformation of the closed-shell folded isomer into the biradical twisted structure of the bis-fluorenyl anthracene has been ascertained by applying the procedure of searching for the Minimum Energy Crossing Point. The conditions favoring the occurrence of spin-state-switching in such classes of polycyclic aromatic hydrocarbon derivatives have been formulated. By varying the size of an acene core and the type of radical substituent, the compounds capable of changing their magnetic properties have been revealed. Considering the unique features of radical-bearing acene-based derivatives, the proposed molecules can be used as functional materials in photonics and electronics.

Impact of Particle Size on the Nonlinear Magnetic Response of Iron Oxide Nanoparticles during Frequency Mixing Magnetic Detection.

Magnetic nanoparticles (MNPs), particularly iron oxide nanoparticles (IONPs), play a pivotal role in biomedical applications ranging from magnetic resonance imaging (MRI) enhancement and cancer hyperthermia treatments to biosensing. This study focuses on the synthesis, characterization, and application of IONPs with two different size distributions for frequency mixing magnetic detection (FMMD), a technique that leverages the nonlinear magnetization properties of MNPs for sensitive biosensing. IONPs are synthesized through thermal decomposition and subsequent growth steps. Our findings highlight the critical influence of IONP size on the FMMD signal, demonstrating that larger particles contribute dominantly to the FMMD signal. This research advances our understanding of IONP behavior, underscoring the importance of size in their application in advanced diagnostic tools.

Topology optimization of non-linear electromagnetic actuator based on Reluctance Network Analysis

Topology Optimization (TO) enables unrestricted exploration within a design domain and is typically based on a spatial discretization that is also used as the mesh for simulation. In this article, we propose to use for the simulation a mesh-based equivalent circuit method termed the Reluctance Network Analysis (RNA), with nonlinear magnetic properties of the material. The simulation tool is then used in a topology optimization process solved with generalized optimality criteria (GOC) method. During the optimization, the sensitivity matrix is needed, and we describe here how to derive the matrix in the case of a nonlinear RNA using Adjoint Variable Method (AVM). Finally, we implemented this topology optimization through a case study of an electromagnetic actuator.

A hybrid energy harvester inspired by bionic flapping wing structure based on magnetic levitation.

A hybrid energy harvester based on magnetic levitation is inspired by the structure of the flapping wing, which consists of two parts: one is a flapping wing structure mounted with a piezoelectric sheet, which can achieve piezoelectric energy harvesting; the other is an intermediate muscle unit, which is vertically arranged by three groups of permanent magnets to achieve magnetic levitation electromagnetic energy harvesting. An electromechanical-electromagnetic coupling model of this harvester is established based on electromechanical coupling characteristics. The simulation analysis can evaluate the magnetic field distribution and nonlinear magnetic properties and also analyze its effects on the output performance. Several experiments are designed to verify the effectiveness of the hybrid energy harvesting structure and to check the influence of the number of magnets on the output power. The maximum output power of the proposed structure can generate 13.61 mW at 4.5Hz excitation.

БЕСКОНТАКТНЫЙ ФЕРРОЗОНДОВЫЙ ДАТЧИК ПОЛОЖЕНИЯ ДЛЯ КОНТРОЛЯ СОСТОЯНИЯ КЛАПАНА

The aim of the study is to develop a non-contact fluxgate position sensor to control the open /closed state of the valve. There are many examples of the use in modern technology of elements or devicesthat interact with a magnetic field. One of the most urgent tasks is to use the influence of the magneticfield as a means of control or as a component of the control environment. The use of magnetoopticalsensors for monitoring the functioning of technical objects is due to their non-contact measure ment method, the ability to measure not only magnetic, but also various other physical quantities, therelative simplicity, reliability and low cost of the design of the sensitive element, flexibility in use, operationin low-temperature and high-temperature environments. One of the sensors of this type is a fluxgatemagnetic field converter. Valves of various pneumohydraulic systems are an example of the object ofintroduction of a fluxgate sensor. The essence of the task is to create a non-contact limit switch of thevalve spool, signaling the closed or open state of the valve and transmitting this information to the controlsystem. It is proposed to divide this task into stages and their sequential implementation. First, asearch and analysis of existing solutions, literature on the topic of research of magnetic transducers iscarried out. Next, a model design of the sensor is developed, according to which a geometric 3D modeland a 2D model of the sensing element are created, and the proposed material of the constituent elementsof the sensor is selected. With the help of numerical methods of computer simulation and mathematicalmodels, the operation of the sensor is simulated and its output characteristics are determinedunder various operating modes. According to the design characteristics, the optimal design and configurationof the sensor's sensing element is selected and calculated. As a result of the simulation, assemblyand working drawings of the sensor are developed. The proposed method for solving the problem ischaracterized by the complexity of studying nonlinear magnetic systems and their modeling. The resultsof this study can be recommended for the development of magneto-optical sensors of this or anothertype and for the study of materials with nonlinear magnetic properties.

Model Free Predictive Current Control Based on a Grey Wolf Optimizer for Synchronous Reluctance Motors

A Model-based predictive current control (MBPCC) has recently become a powerful advanced control technology in industrial drives. However, MBPCC relies on the knowledge of the system model and parameters, being, therefore, very sensitive to parameters errors. In the case of the synchronous reluctance motor (SynRM), where the parameters vary due to its ferromagnetic structure and nonlinear magnetic properties, MBPCC performance would suffer significantly. Accordingly, in this paper, a Grey Wolf Optimizer based model-free predictive current control (GW-MFPCC) of SynRM is proposed, to skip all the effects of the model dependency and parameters uncertainty. The proposed method predicts the stator current through tracking the minimum cost function using the grey wolf optimizer. The proposed GW-MFPCC scheme is compared to MBPCC, and its effectiveness is evaluated and confirmed by experimental results.

3-Phenyl-4-(prop-2-en-1-yl)-5-[(prop-2-en-1-yl)sulfanyl]-4H-1,2,4-triazole

1,2,4-Triazoles appear to be attractive substances due to their wide range of applications. Previously 3-phenyl-4-(prop-2-en-1-yl)-5-[(prop-2-en-1-yl)sulfanyl]-4H-1,2,4-triazole (Atr) has proven to be an effective precursor for us to prepare Cu(I)-π,σ-coordination compounds with nonlinear optical and magnetic properties. In this study, we present the structural characterization of Atr by a single-crystal X-ray diffraction method. The crystals are monoclinic, Sp.gr. P21, Z = 2, unit cell dimensions: a = 5.6967(3), b = 7.8045(3), c = 14.9327(7) Å, β = 91.113(4)°, V = 663.78(5) Å3 at 150 K. To analyze the intermolecular interactions in the crystal structure of Atr, a DFT computational study was also performed.

БЕСКОНТАКТНЫЙ ФЕРРОЗОНДОВЫЙ ДАТЧИК ПОЛОЖЕНИЯ ДЛЯ КОНТРОЛЯ СОСТОЯНИЯ КЛАПАНА

The aim of the study is to develop a non-contact fluxgate position sensor to control the open/ closed state of the valve. There are many examples of the use in modern technology of elementsor devices that interact with a magnetic field. One of the most urgent tasks is to use the influenceof the magnetic field as a means of control or as a component of the control environment. The useof magneto-optical sensors for monitoring the functioning of technical objects is due to their noncontactmeasurement method, the ability to measure not only magnetic, but also various otherphysical quantities, the relative simplicity, reliability and low cost of the design of the sensitiveelement, flexibility in use, operation in low-temperature and high-temperature environments.One of the sensors of this type is a fluxgate magnetic field converter. Valves of variouspneumohydraulic systems are an example of the object of introduction of a fluxgate sensor.The essence of the task is to create a non-contact limit switch of the valve spool, signaling theclosed or open state of the valve and transmitting this information to the control system. It is proposedto divide this task into stages and their sequential implementation. First, a search and analysisof existing solutions that implement the position sensor using the fluxgate control method iscarried out to improve the design being developed. Next, the initial design of the sensitive elementof the fluxgate transducer is developed, according to the initial design, a geometric 3D model ofthe sensitive element is created, and the proposed material of the constituent elements of the sensoris selected. With the help of numerical methods of computer simulation, the operation of thesensor is simulated and its output characteristic is determined under various operating modes.According to the design characteristics, the optimal design and configuration of the sensor's sensingelement is selected and calculated. As a result of the simulation, assembly and working drawingsof the sensor are developed. The proposed method for solving the problem is characterized bythe complexity of studying nonlinear magnetic systems and their modeling. The results of this studycan be recommended for the development of magneto-optical sensors of this or another type andfor the study of materials with nonlinear magnetic properties.

Improved nonlinear optical and magnetic properties of Eu-doped nano-maghemite

Improved nonlinear optical and magnetic properties of Eu-doped nano-maghemite

Fourier-Based Modeling of an Induction Machine Considering the Finite Permeability and Nonlinear Magnetic Properties

Performance prediction of induction machines (IMs) is highly dependent on the accuracy of the material characteristics and geometry of the machine during the modeling stage. To reduce the complexity of an IM model, normally the slotting effects are neglected. Likewise, the permeability of the stator and rotor cores are assumed to be infinite leading to an ideal set of partial differential equations (PDEs) for homogenous and isotropic materials. In this paper, the permeability of the stator and rotor cores are assumed not to be infinite and the slotting effects are taken into consideration to propose a more accurate and realistic model of an IM to reduce the discrepancies between the performance expectations and actual results. Fourier-based (FB) magnetic field approach is used to fulfill this aim via anisotropic layer theory (ALT) enabling the proposed model to include distortion of magnetic flux in the slotted regions. Air-gap flux density, core losses, efficiency and torque of an IM are predicted via the FB model and are validated through the finite element analysis (FEA) and experimental studies.

Iron loss estimation of soft magnetic materials for power transformers considering hysteretic properties

AbstractThis paper investigates an efficient iron loss calculation method for soft magnetic materials of power transformers. To accurately estimate iron losses in the materials such as structural steels and magnetic shielding, the magnetic field analysis taking account of the nonlinear magnetic properties is considered to be effective. In this paper, quasi‐DC magnetic properties of the soft magnetic materials are measured and the iron losses are calculated by using a three‐dimensional finite element method. Furthermore, the effect of considering hysteretic properties on the accuracy of the iron loss calculation is discussed based on a theoretical representation of eddy current loss in a conductive rectangular plate.

Acene-Linked Zethrenes and Bisphenalenyls: A DFT Search for Organic Tetraradicals.

Polycyclic aromatic hydrocarbons are of special interest due to their promising nonlinear optical and magnetic properties. A series of acene-linked zethrenes and bisphenalenyls comprising from five to nine benzene rings in the linker group have been computationally studied by the DFT UB3LYP/6-311++G(d,p) quantum-chemical modeling of their electronic structure, possible spin states, and exchange interactions. The zethrenes with octacene and nonacene linkers as well as bisphenalenyls comprising heptacene, octacene, and nonacene linker groups have been revealed to possess tetraradicaloid nature, which makes them promising building blocks for organic optoelectronic and spintronic devices. The results obtained open a way of constructing tetraradicaloid organic molecules characterized by the presence of two types of paramagnetic centers.

Eddy-Current Losses Estimation on Nonlinear Magnetic Property in Single-Phase Wound Core

Eddy-current analysis and losses estimation are significant components in the optimized design of the tractive transformer. The conventional analytical method forces to linearize the nonlinear magnetic property and as an important quantity in the calculation, the permeability is only acquired dependent on the empirical method. Furthermore, the computational precision is often difficult to assure in losses estimation when distorted excitation originated from nonlinear magnetized relation in electrical steel is neglected. In our study, the eddy-current field problem is delicately solved by analytical deduction, in which the nonlinear constitutive relation toward media and the harmonic component in the excitation source are sufficiently considered. Compared with the accuracy of the traditional formula, the proposed model achieves better accuracy on eddy-current losses with finite-element analysis, especially when the operating condition is closed to magnetic saturation.

Features of field modeling of electromagnetic processes of trolley busbar

Purpose. Research and analysis trolley busbar’s parameters in condition of higher current harmonic actions, with taking into account the structural features of nonlinearity of magnetic and electrical properties of materials, proximity effects, surface and external surface effects.
 Methodology. The researches were carried out using the electromagnetic field theory methods, the electrical circuit theory, mathematical physics, finite elements, interpolation, approximation and regression analysis.
 Findings. The mathematical spatial model of electromagnetic processes in a steel trolley busbar in time statement of a problem of distribution of an electromagnetic field is developed. The dependences of the distribution of equipotential lines of the resulting z-component of the magnetic potential vector along the busbar, as well as the distribution of the resulting normal component of magnetic induction and magnetic field strength in the transverse (XY) cross section at non-sinusoidal current in busbar trolleys is obtained. Along the length of the busbar, in their cross section, the magnetic field tends to a plane-parallel shape it is proved. The error of the modulus of the vector magnetic potential along the length of the busbar does not exceed 0.9-1.2%. To reduce the dimension of the problem, computational resources and calculation time, a two-dimensional plane-parallel mathematical model in the frequency setting of the electromagnetic field distribution is proposed. To take into account the nonlinear magnetic properties of steel trolleys, to determine the effective magnetization curve for the nonlinear two-dimensional problem of the electromagnetic field of the busbar it is proposed. The verification results, according to the calculated voltage drop, confirm the high accuracy of the calculation and the reliability of the obtained results (error does not exceed 1.88% ÷ 2.06%) of the two-dimensional model in the frequency setting relative to the spatial model in the problem of time-dependent electrical -magnetic field is obtained.
 Originality. A mathematical two-dimensional model of electromagnetic processes in the frequency formulation of the problem of electromagnetic field distribution in a trolley busbar is proposed, which takes into account design features, nonlinearity of magnetic and electrophysical properties of materials, proximity effects, surface and external surface effects, influence of harmonic current components power transmission, which allows with high accuracy and efficiency of numerical implementation to determine the parameters of the bus trolls for the corresponding values of the amplitudes and frequencies of the frequencies harmonics of the current.
 Practical value. Verification of the calculated voltage drop confirms the high accuracy of the calculation and the reliability of the results (error does not exceed 1.88% ÷ 2.06%) of the two-dimensional model in the frequency reference relative to the spatial model in the problem of time-dependent electromagnetic field distribution is performed.

The Correlation between Non-Linear Acoustic and Magnetic Properties and Local Misorientation Induced by Plastic Strain in Metastable Austenitic Stainless Steel

The Correlation between Non-Linear Acoustic and Magnetic Properties and Local Misorientation Induced by Plastic Strain in Metastable Austenitic Stainless Steel

Modeling of magnetic fields and signals of a ferromagnetic pipe flaw detector induced by a through hole defect

A numerical model has been developed for interaction of the magnetizing field of a short solenoid with a ferromagnetic pipe exhibiting a through hole in the wall, which takes into account nonlinear magnetic properties of the test object. This model was used to calculate spatial distribution of magnetic induction in the pipe wall and spatial distribution of the components of the magnetic induction vector near the pipe surface with a through hole. The validity of the numerical model was confirmed by physical modeling results. The results of theoretical and experimental studies were used to develop a simplified analytical model that describes behavior of the magnetic field of the defect and the electrical signal of the induction transducer of a magnetic flaw detector that implements the method of magnetic flux leakage. It is shown that the dependence of the signal of the induction transducer induced by the through hole on the gap is close to a linear one, and its dependence on the hole diameter is close to a quadratic one. The results obtained in the study can be used for creation, numerical modeling and measurement of magnetic fields.

Cubic magnetic response of diamagnetic molecules via third-order electronic current density.

An approach to nonlinear magnetic properties of a diamagnetic molecule in the presence of a strong homogeneous magnetic field B is proposed, introducing the notion of third-order electronic current density and associated fourth-rank current density tensors via a perturbation expansion. It is shown that cubic magnetic response properties, e.g., fourth-rank magnetizability and fourth-rank nuclear magnetic shielding, can be expressed by relationships alternative to those arrived through perturbation theory by means of third-order current density. A sum rule, providing a condition in integral form for electron charge conservation to the third order in B, has been obtained.

Nonlinear Magnetic Properties of Magnetic Fluids for Automotive Applications

The external magnetic field required to activate a magnetic fluid in an industrial application is sufficiently large that magnetization is no longer a linear function of the external field strength, i.e. magnetic fluids exhibit nonlinear characteristics. The aim of our research was to develop a measuring system which is capable of determining the nonlinear AC susceptibility of magnetic fluids at discrete frequencies and in the presence of a high-intensity driving magnetic field. The measurement of susceptibility is based on the determination of the change in frequency of a low-intensity field, which is generated by an LC oscillator. The application of sinusoidal excitation to the material results in a variation in the susceptibility that modulates the frequency of the measured low-intensity field and in the appearance of higher-order harmonics of the driving field. The higher-order components of the nonlinear AC susceptibility are extracted from the measured response by Fourier analysis. By applying the measuring system, the nonlinear susceptibility of water-based ferrofluids (Ferrotec’s EMG 700) and its dependence on the magnetic field strength were investigated.

Magneto-Thermal Analysis of an Axial-Flux Permanent-Magnet-Assisted Eddy-Current Brake at High-Temperature Working Conditions

This article proposes an analytic coupled magneto-thermal analysis of an axial-flux (AF) permanent-magnet-assisted (PMA) eddy-current brake (ECB) at high-temperature working conditions. In the topology investigated, permanent magnets (PMs) are placed into stator slot openings to increase the braking torque production capability. This modification enables to control the magnet flux by altering the dc excitation current. However, the utilization of PMs will make the construction vulnerable at high operating temperatures simply because the magnet properties and the brake capability are strongly dependent on temperature. Such problems require complex coupled multiphysics finite-element analyses to obtain the actual brake performance. The proposed approach offers a simple and effective solution that consists of magnetic and thermal models, which are coupled to each other in the time domain. The nonlinear electrical, magnetic, and thermal properties are influenced by the temperature variation in time. An AF-PMA-ECB prototype is manufactured to validate the proposed coupled models and the experimental studies confirm that the proposed approach provides very practical results to determine the working conditions of the AF-PMA-ECB at high-temperature operations.

Three-dimensional numerical study of heat-affected zone in induction welding of tubes

Purpose Quality of the weld joint produced by high-frequency induction (HFI) welding of steel tubes is attributed to a number of process parameters. There are several important process parameters such as the speed of the welding line, the angle of the approaching strip edges, the physical configuration of the induction coil, impeder, formed steel strip and weld rolls with respect to each other, the pressure of the weld rolls and frequency of the high-frequency current in the induction coil. The purpose of this paper is to develop a 3D model of tube welding process that incorporates realistic material properties and movement of the strip. Design/methodology/approach 3D numerical simulation by the finite element method (FEM) can be used to understand the influence of these process parameters. In this study, the authors have developed a quasi-steady model along with the coupling of electromagnetic and thermal model and incorporation of non-linear electromagnetic and thermal material properties. Findings In this study, 3D FEM model has been established which gives results in accordance with previously published work on induction tube welding. The effect of the Vee-angle and frequency on the temperature profile created in the strip edge during the electromagnetic heating is studied. Practical implications The authors are now able to simulate the induction tube welding process at a more reasonable computational cost enabling an analysis of the process. Originality/value A 3D model has been developed for induction tube welding. A non-linearly coupled system of Maxwell’s electromagnetic equation and the heat equation is implemented using the fixed point iteration method. The model also takes into account non-linear magnetic and thermal material properties. Adaptive remeshing is implemented to optimise mesh size for the electrical skin depth of induced current in the strip. The model also accounts for the high welding-line speeds which influence the mode of heat transfer in the strip.