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This paper presents an engineering modeling methodology for magnetostrictive materials based on a simplified piezo-electric governing equation. For verifying the modeling performance, a proof-of-concept non-contact strain sensor utilizing a prototype magnetostrictive (Fe–Ga alloy, Galfenol) strip on a steel plate is used to evaluate sensor performance prediction. Typically, the performance of Galfenol is measured in a compressional load region because it has a higher response. However, in this paper, we are aiming to develop a sensor for tensile stress measurement. To achieve a compression effect from a tension load in the sensing element, a Galfenol strip is aligned perpendicular to a tension bar so that tension in the bar creates compression in the strip via the Poisson effect. The experimental setup in this paper consists of a polycrystalline Galfenol strip bonded in the horizontal direction of a steel dog-bone shaped tension specimen. Permanent magnets are attached at each end of the Galfenol strip to provide an even magnetic bias field through the strip. The magnetic flux through the Galfenol strip is measured with non-contact Hall sensors during the tensile load test. The simulation results agree well with the experiments for the value of $H$ studied. [ABSTRACT FROM AUTHOR]

The utilization of a bismuth-substituted iron garnet as a magnetooptic Faraday rotator (MOFR) has been reported for all-optical networking purposes as well as for other applications. Our measurements and observations demonstrate that the MOFR saturates once a significantly large magnetic field (>225 G) is applied. After the applied magnetic field enters the saturation region, the material’s magnetic domains can become pinned at intermediate levels of magnetization. Pinning in this form has not been reported nor well studied for this application. In this paper, a method to detect and describe anomalous pinning in terms of Faraday rotation is presented. Measurements on the changes in the state of polarization that a pinned material produces are examined. This paper will also present practical methods for unpinning the MOFR material, which are traditionally considered to be challenging. [ABSTRACT FROM AUTHOR]

In this paper, we propose a loss calculation method considering minor hysteresis loops for permanent magnet (PM) motors driven by pulsewidth modulated (PWM) inverters. In the governing equation of the proposed method, both the effects of the major and minor hysteresis phenomena are expressed by a reaction magnetic field. This field is determined by iterative calculations of finite-element analysis (FEA) with a simple hysteresis modeling that considers the minor loops. The proposed method is applied to a PM motor, and the experimental verification is carried out. It is clarified that the minor hysteresis loops affect not only the hysteresis loss but also the eddy current loss because the skin depth varies with the differential permeability of the minor loops. [ABSTRACT FROM AUTHOR]

This paper presents an identification algorithm of the scalar Preisach model by using a set of symmetric minor hysteresis loops and suggests an improved vector Preisach model to describe the vector and anisotropic hysteresis behavior of a non-oriented (NO) electrical steel sheet (ESS) under rotating magnetic fields. Symmetric minor hysteresis loop is quite easy measured, so an identification algorithm based on symmetric minor hysteresis loop instead of first-order reverse curve is presented in this paper. The vector Preisach model employs a nonlinear coefficient, which is a function of magnitude and a direction of magnetic flux density, to describe the anisotropic property of the NO ESS and increases the numerical accuracy. The validity of the suggested vector Preisach model is investigated through comparisons with the experimental results under various magnetic field conditions. [ABSTRACT FROM AUTHOR]

Arrays of nanosized hollow spheres of Ni were studied using micromagnetic simulation by the Object Oriented Micromagnetic Framework. Before all the results, we will present an analysis of the properties for an individual hollow sphere in order to separate the real effects due to the array. The results in this paper are divided into three parts in order to analyze the magnetic behaviors in the static and dynamic regimes. The first part presents calculations for the magnetic field applied parallel to the plane of the array; specifically, we present the magnetization for equilibrium configurations. The obtained magnetization curves show that decreasing the thickness of the shell decreases the coercive field and it is difficult to obtain magnetic saturation. The values of the coercive field obtained in our work are of the same order as reported in experimental studies in the literature. The magnetic response in our study is dominated by the shape effects and we obtained high values for the reduced remanence, Mr/MS = 0.8 . In the second part of this paper, we have changed the orientation of the magnetic field and calculated hysteresis curves to study the angular dependence of the coercive field and remanence. In thin shells, we have observed how the moments are oriented tangentially to the spherical surface. For the inversion of the magnetic moments we have observed the formation of vortex and onion modes. In the third part of this paper, we present an analysis for the process of magnetization reversal in the dynamic regime. The analysis showed that inversion occurs in the nonhomogeneous configuration. We could see that self-demagnetizing effects are predominant in the magnetic properties of the array. We could also observe that there are two contributions: one due to the shell as an independent object and the other due to the effects of the array. [ABSTRACT FROM PUBLISHER]

In previous studies on precise computation methods of iron loss, it has been shown that the 1-D dynamic magnetic field analysis with hysteresis in post-processing is effective. However, there is a problem in that the hysteresis makes the convergence of nonlinear iterations unstable. This paper proposes a stabilization method for the 1-D dynamic magnetic field analysis with hysteresis. The proposed method is characterized as an approach for improving the initial value and the step size in the Newton–Raphson method. The results of this paper showed that the convergence characteristic of the nonlinear 1-D magnetic field analysis for variety flux density waveforms of each part in an electric motor is improved using the proposed method. [ABSTRACT FROM AUTHOR]

Recently, the demagnetization has been actively researched to reduce the magnetic field of a warship according to the development of the magnetic detection technology of the magnetic mines. In these studies, it was assumed that the warship was composed of one magnetic material in order to establish an effective deperming protocol. However, since the actual warship was composed of various materials, the magnetic interaction between the materials inevitably occurs during the demagnetization process. Due to the interaction, demagnetization may not be performed well. Therefore, in this paper, the effects of interactions in demagnetization of multiple materials were studied by using the Preisach model, and the optimal protocol was proposed. [ABSTRACT FROM AUTHOR]

In the fabrication of linear magnetic tunnel junction (MTJ) sensors, the utilization of magnetic bias field along the easy-axis direction makes the response of MTJ nonlinear, and the Néel and magnetostatic coupling usually induces a strong interlayer coupling field along the hard-axis direction. In this paper, we investigated the influence of hard-axis and easy-axis bias fields on the linearity of MTJ magnetic sensor. The prediction and optimization of linearity were done by applying an appropriate hard-axis bias field in the specific easy-axis bias field and the practical tunnel magneto-resistance (TMR) ratio, and the model was verified by experiments. This paper can give guidance to improve the linearity and to maximize the practical TMR ratio of the MTJ sensors under a given linearity requirement. [ABSTRACT FROM AUTHOR]

This paper introduces a comparative study of two different hysteresis models, limiting loop model and elemental operator model. The former is regarded as a mathematical approach based on the traditional Preisach model. To circumvent the difficulty of determining the distribution function in the Preisach model, the data of the limiting hysteresis loop and a function transform on the Preisach diagram are employed. The latter is a physical method which adopts a vectorial elemental operator with biaxial anisotropy based on the magnetization mechanisms of the ferromagnetic material. These two models are analyzed and compared in terms of the underlying principle, numerical implementation, and calculation accuracy in this paper. To verify the introduced models, the magnetic properties of non-oriented silicon steel Lycore-140 and soft magnetic composite material Somaloy 500 under alternating excitations are measured and compared with simulated results, which show the validity and practicability of the models but with different calculation accuracy and speed. [ABSTRACT FROM AUTHOR]

This paper presents the characteristic analysis and experiment of surface-mounted type variable-flux permanent-magnet machines considering magnetization and demagnetization based on electromagnetic transfer relations. For this purpose, we derive the analytical solutions for the magnetic fields generated by the magnetization level of AlNiCo magnets and currents on the basis of the transfer relations in terms of a 2-D polar coordinate system. The magnetization levels of the AlNiCo magnets are determined by the magnetic fields generated by the armature reaction field. A 2-D permeance function is also introduced to consider slotting effects. The analytical results of the magnetic field are validated extensively with finite-element (FE) analyses. On the basis of these solutions, the induced voltage is also determined analytically. Finally, the predictions are compared with FE analyses and measured data to confirm the validity of the analysis methods presented in this paper. [ABSTRACT FROM AUTHOR]

This paper presents a theoretical and experimental study on high-frequency (>5000 Hz) output characteristics of the giant magnetostrictive transducer (GMT) at varied operating conditions. Based on the Jiles–Atherton model, Maxwell’s equations, Newton’s law, and Fourier’s heat transfer equation, a nonlinear electromagnetic–mechanical–thermal multi-field coupled finite element model for GMT is established. The output displacement amplitude of the magnetostrictive rod and the acceleration of vibrating horn at the GMT device are measured and analyzed at varied exciting amplitude of ac magnetic field and frequencies (from 5600 to 7000 Hz). The frequency dependences of permeability and magnetoelastic coupling coefficient obtained from the experimental results are used in revising the model parameters. These output characteristics analysis results can provide theoretical and experimental guidance in the optimization of structural design and precise controlling for high-frequency GMT system. [ABSTRACT FROM AUTHOR]

Cobalt-rich amorphous wires have been extensively used as a core of many types of magnetic field sensors, notably of a fundamental model orthogonal fluxgates, because they allow us to manufacture sensors with very low noise. However, commercial wires are available only in one diameter, namely, $125~\mu \text{m}$ ; therefore, most of the literature is always referred to this diameter. In this paper, we investigated the effects of different diameters versus the noise of the sensor. Our purpose is to understand that if there is a room for improvement of noise by producing amorphous wires with different diameters. We casted wires with (Co0.94Fe0.06)72.5Si12.5B15 composition and a diameter spanning from 80 to $220~\mu \text{m}$ , and we discovered that the wires show crystalline structure starting from $200~\mu \text{m}$. This means we can increase the diameter to values higher than $125~\mu \text{m}$ and still achieve an amorphous structure, considering the upper limit of $200~\mu \text{m}$. Then, we studied the noise of the sensors based on wires with three different diameters, namely, 80, 120, and $175~\mu \text{m}$. Because the diameter affects the demagnetizing factor, we also changed the length of the wire in the range from 40 to 120 mm. We discovered that increasing the diameter of the wire always decreases the noise, regardless of the demagnetizing effect, which indicates larger cross section of the wire is a predominant factor. [ABSTRACT FROM AUTHOR]

In this paper, combined rational and power functions are used to represent magnetization curves of high magnetic permeability ferromagnetic materials. The proposed functions cover much wider range of magnetic fields than functions currently used in simulation software packages. The objective is to present simple functions for approximation of magnetization curves with minimum number of unknown constants. The calculated functions are finally compared with measured magnetization curves to validate the precision in a wide field range from 10−2 to 106 A/m. [ABSTRACT FROM AUTHOR]

Barkhausen noise emissions occur in ferromagnetic materials on application of an externally varying magnetic field. These emissions primarily occur due to the presence of pinning sites or discontinuities within a material which act as inhibitors to domain wall motion. Overall, Barkhausen noise emissions can capture variations in microstructure, chemical composition, lattice strain, and grain size, and can detect the presence of residual stresses in materials. In this paper, the Barkhausen noise response for a Jominy end-quench test steel sample is examined. Microstructural variations in the form of constituent phases, such as martensite, bainite, pearlite, or ferrite, can be detected via changes in Barkhausen noise signatures. Through Barkhausen noise measurements, it is observed that characteristic peaks corresponding to different phases appear in the spectrum. The characteristic peaks become distinct when the contribution to Barkhausen noise from individual phases becomes significant. This analysis method may be further used to monitor microstructural evolution, and thus understand the contributions of constituent phases to material properties. The technique may be used as a potential tool for the nondestructive evaluation of ferromagnetic materials employed in industrial applications. [ABSTRACT FROM AUTHOR]

This paper presents a simple dynamic vector-play model to calculate the iron loss and describe the vector hysteresis behavior of a non-oriented (NO) electrical steel sheet (ESS) under 50 Hz rotating magnetic fields. Based on the iron loss separation theory, the proposed model is separated to the static hysteresis component and eddy current component. The static hysteresis component is constructed by vector play model, which is identified by using 1 Hz minor B – H loops. And two coefficients \omega x and \omega y are introduced to consider the anisotropic property of NO ESS and the excess loss of eddy-current component under 50 Hz magnetic field. The validity of the proposed dynamic vector hysteresis model is verified by comparing it with the experimental results under various 50 Hz magnetic field conditions. [ABSTRACT FROM AUTHOR]

In the frame of this paper, the synthesis of self-assembled magnetic and biocompatible nanovehicles movable in aqueous solutions by a magnetic field gradient is presented. The systems consist of a mesoporous silicon template and encapsulated iron oxide nanostructures, both materials known to be biocompatible. Two routes are applied to produce iron oxide nanostructures embedded within porous silicon. First, readily synthesized superparamagnetic iron oxide nanoparticles (NPs) are infiltrated into the pores. The second attempt is the chemical deposition of iron oxide structures inside the PSi templates. Concerning the adjustability of the magnetic properties of the system the loading procedure of the PSi with iron oxide NPs will be elucidated in detail as well as the growth of iron oxide structures within the pores. An assessment of the iron oxide deposition dependent on the template and the chemical parameters as well as of the magnetic properties in dependence on the particle size and template morphology of the nanocomposite will be presented. A further approach is the transition from a magnetite to the stable hematite phase by heat treatment of the specimens. A sufficient filling leading to a magnetization high enough for the movement of the nanovehicles within aqueous surroundings (e.g., body fluid) by magnetic field gradients could be reached easily. [ABSTRACT FROM AUTHOR]

This paper proposes a novel estimation method for iron loss considering hysteretic property. In the proposed method, iron loss considering hysteretic property is estimated with play model as a postprocessing of usual finite element magnetic field analysis based on ordinary magnetization curve. Numerical results are compared with measured results to demonstrate the effectiveness of the proposed estimation method for iron losses. [ABSTRACT FROM AUTHOR]

This paper proposes an equivalent magnetic hysteresis (B–H) curve for magnetic multiscale problems of complex materials composed of electrical conductors separated by insulating material. The conventional method, which assigns equivalent material constants to each material, cannot properly express the local eddy current loss and the extra magnetic field derived from the local eddy current. To solve this problem, we derive the magnetic hysteresis curve from the volume-averaged magnetic flux density and the surface magnetic field in the micro-model, and apply this curve to the macro-model. The mesh number of the novel macro-model is reduced to around one-tenth that of the micro-model. Magnetic hysteresis is treated by a free energy magnetic hysteresis model, and the macro-model ignores electrical conductivity. The magnetic hysteresis curve and the numerically calculated losses are consistent in the micro- and macro-models. The proposed method well expresses the local eddy current phenomena. [ABSTRACT FROM AUTHOR]

This paper proposes a homogenization method for a laminated iron core taking into account hysteretic property. The proposed method is applicable to a static or low-frequency problem neglecting eddy currents induced by the magnetic flux parallel to the lamination. Furthermore, we apply the proposed homogenization method to finite-element magnetic field analyses to demonstrate its effectiveness. As a consequence, it is verified that the proposed homogenization method can accurately estimate a hysteresis loss of a laminated iron core and decrease computational costs. [ABSTRACT FROM AUTHOR]

This paper presents a laboratory test procedure to determine the parameters of the inverse hysteresis model (IHM) applicable to single-phase toroidal transformer low-frequency modeling. The model parameters are obtained through a fitting procedure of the history-independent IHM of a series of open-circuit experiments and waveform recordings. These experiments can be easily executed during the transformer acceptance testing at the factory laboratory. The performance of the model is verified under various operational conditions, such as sinusoidal excitation, varied frequencies and voltages, and non-sinusoidal excitations. The results show that the model performs very well under all tested conditions giving great confidence that the proposed method can be used for parameter determination. [ABSTRACT FROM PUBLISHER]

The measurement of biological targets using nanoparticle magnetic markers has been extensively studied for its applications in magnetic immunoassays (MIAs). Compared with the optical immunoassay method, the MIA methods have some attractive characteristics such as a wash-free process that does not need bound/free marker separation and the ability to detect biological targets in a nebulous liquid. In addition, the wash-free process is very fast. In this paper, we tried to reduce the reaction time for the antigen-antibody reaction in order to make the MIA method more attractive. The reduction in reaction time and the detection characteristic of biological targets were demonstrated using C-reactive proteins (CRPs) as biological targets for diagnosing inflammation. To shorten the reaction time, a magnetic-shaking method using the magnetic field gradient from a neodymium magnet was developed. When comparing the reaction times with and without magnetic shaking, it was found that the reaction time decreased with magnetic shaking for all CRP concentrations. Even after the magnetic-shaking treatment, the dependence of the CRP concentration on the magnetic signal was observed. The number of surface modifications per magnetic marker and the magnetic marker concentration also affected the reaction time. In order to obtain the desired measurement range based on the CRP response characteristic, it is necessary to optimize the number of magnetic markers and polymer beads used. [ABSTRACT FROM AUTHOR]

This paper proposes a frozen permeability method for magnetic field analyses considering hysteretic property. In the proposed method, the effect of magnetic hysteresis is regarded as a reaction field in a broad sense with respect to the corresponding normal magnetization curve. To verify the effectiveness of the proposed method, the numerical results of torque separation in a hysteretic magnetic field analysis of an interior magnet synchronous motor with concentrated winding are discussed. [ABSTRACT FROM AUTHOR]

This paper investigates the online fault detection (FD) of the inter-turn short-circuit (ITSC) fault in direct torque control (DTC)-driven induction motors (IMs). We conducted the investigations of harmonic, inter-harmonic, and sub-harmonic contents for FD purposes. The harmonics in the flux leakage spectrum appear as a result of diverse causes including stator fault, DTC reaction to the fault, switching activities, and core saturation effect. Physics-based co-simulation was held through the coupling between a finite-element model (FEM) of the faulty IM and the circuit simulation of DTC. Its advantages are: 1) the IM harmonic contents including stator slots, rotor slots, saturation, switching activity, and fault are simulated and 2) dangerous experimentations of a faulty IM can be avoided. Therefore, we can safely study all the characteristics on a faulty IM. We exploited FEM for the verification of the experimental harmonic signatures of the scattered magnetic field. We verified the online FD technique based on the radiated magnetic field’s spectrum through the co-simulation and experimental results. This indicated that the method is able to correctly detect the ITSC faults with 1% severity factor. [ABSTRACT FROM AUTHOR]

This paper presents the analytical solution of levitation problem for both magnetically anisotropic and conductive balls. The magnetic field exerts eddy currents in magnetic and conductive balls. The forces, both Lorentz (of eddy current) and material (caused by inhomogeneity of reluctivity), lead to the levitation of the ball. The electromagnetic field is determined by means of variable separation method. The forces, both Lorentz and material acting upon the ball, are calculated. Power losses are calculated twice by means of Joule volume integral and Poynting surface integral. The total force is evaluated three times by Maxwell, coenergy, and Lorentz methods. Levitation force and power losses versus frequency are presented. Asymptotic relations for levitation force and power losses are derived. The comparison to levitating disk at the same volume is presented. [ABSTRACT FROM AUTHOR]

Rotational magnetic flux in the plane of steel laminations causes core losses which far exceed than alternating magnetic flux. Traditional testing methods such as Epstein frame detected only in one direction may lead to inaccurate predictions of core losses. This paper developed a 3-D magnetic properties testing device to measure the magnetic properties of high grain-oriented silicon steel. By using the automatic control system and novel surface B–H sensing coils, the dynamic magnetic hysteresis properties of the silicon steel are accurately measured with a static magnetic field along the laminated direction of the specimen. Finally, an ellipsoid magnetic anisotropy model is established which parameters can be identified by the magnetic measurement results with biased magnetic field. [ABSTRACT FROM AUTHOR]

Brushless doubly fed machine (BDFM), a new type of adjustable-speed machine with special structure, shows promising features for the field of variable frequency speed regulation and wind power generation due to its inherent characteristics. However, the traditional loss calculation method is no longer applicable due to the special structure and complex magnetic field distribution of BDFM, especially for the proposed novel hybrid rotor structure which has better coupling ability than the commonly used rotor structures such as cage rotor and reluctance rotor. In this paper, in order to calculate the core loss accurately, an improved E&S model is applied to BDFM with hybrid rotor, and the analysis and calculation procedure are presented. In addition, based on the time-stepping finite-element model and harmonic analysis method, three different core loss models are established and compared with the proposed improved E&S model. Furthermore, the experimental result from a BDFM with hybrid rotor prototype is compared with the calculation results obtained by the above models, and the accuracy and feasibility of the improved E&S model are verified. [ABSTRACT FROM AUTHOR]

Nanocrystalline (NC) alloy may confront saturation problems with different high-frequency operation circumstances, which are summarized as two typical situations in this paper. One case is “dynamic saturation (DS)” where the alternating magnetic field contains the weak dc biasing field. Another situation is “static saturation (SS)” where the hybrid field comprises not only the weak time-varying field but also the strong dc biasing field. The external and internal factors that affect the saturation magnetization process for the NC alloys were analyzed, under two types of saturation magnetic fields. Two parameters including the saturation time and the rotational velocity of magnetic moment were employed. The external factors, which determine the working condition of the NC alloys, are the dc biasing field and the frequency of the alternating field. The effects of the above two factors are related to the type of saturated magnetic field. In the DS field, the promoting effect of frequency increase on the magnetization process is greater than that of the biasing field, while in the SS field, the opposite is true. The internal factor, which is the grain size, is essential to the soft magnetic properties of the NC alloys. The effects of this factor are independent of the type of saturation field. Increasing the grain size of the NC alloys will delay the magnetization process. [ABSTRACT FROM AUTHOR]

This paper compares two different identification methods of a static rate-independent energy-based hysteresis model with regard to the dynamic hysteresis loop shape prediction when coupled to the parametric magnetodynamic lamination model. The values of hysteresis model parameters are determined solely based on the quasi-static major loop. A semiphysical approach identifying the reversible and irreversible field components independently and a purely mathematical scheme using a differential evolution optimization algorithm determining all parameters simultaneously are compared. Both variants of parameter identification are analyzed in terms of hysteresis loop shape prediction for quasi-static as well as dynamic loops. [ABSTRACT FROM AUTHOR]

The systematic effects of applied current amplitude to the magnetizing coil, distance between the poles of the electromagnetic yoke, magnetic excitation frequency, sensitivity and frequency response of magnetic Barkhausen noise (MBN) pickup coil, and the geometry of the test sample on the applied magnetic field strength, the tangential magnetic field strength, and the MBN signal profile are presented in this paper. The influence of different parameters is discussed with measurement results obtained from harder case-carburized steel and softer spheroidized annealed steel samples. This paper shows the importance of maximizing the shape of the MBN profile for an appropriate evaluation of ferritic steels. [ABSTRACT FROM AUTHOR]

This paper describes an analysis method for inductance and iron loss considering the magnetic hysteresis property in reactors. We discuss inductance calculation methods based on magnetization curves and hysteresis loops. Furthermore, we propose a novel iron loss analysis method under ac excitation with single high-frequency ripples with low computational cost. These numerical results are compared with the experimental results. [ABSTRACT FROM AUTHOR]

Recent advances have been made into modeling the soft-magnetic materials using the surface charge model. Until now, the model has only been used to model the field outside the soft-magnetic material. To include the saturation in the future, the magnetic field inside the material should be known. In this paper, the model is used to calculate the field inside the material when three different shapes of boundaries are considered. Comparing the results with Finite Element Method shows that the differences in the air region are <1 mT and those in the soft-magnetic region are <4 mT. Larger discrepancies can, however, occur near the corner of the material. [ABSTRACT FROM AUTHOR]

Magnetic flux leakage (MFL) technique is generally considered as an efficient and effective nondestructive testing method, which has been widely used in the drill pipe detection in oil field. This paper aims at studying the magnetic concentrating effect, and proposing a method of gathering the MFL by means of magnetic concentrating device. Electromagnetic finite-element analysis shows that pipe MFL signals centralize near defects obviously and the leakage signals detected by Hall elements enhance greatly as magnetic concentrating structure can collect useful magnetic component. A drill pipe MFL experiment confirms the analysis results that the probe with magnetic concentrating device could obviously improve SNR of MFL signals, increase measuring the width of defects and reduce the requirements of liftoff value. Therefore, it is of great help to improve pipe leakage flux testing sensitivity. [ABSTRACT FROM AUTHOR]

A new closed-loop magnetic current sensor is presented in this paper. The sensor consists of two toroidal magnetic cores. One core works in fluxgate principle for the measurement of dc and low-frequency ac, and the other one is used as a current transformer for higher frequency application. Based on the simulation results, a prototype was designed, and the test results have a good agreement with the simulation results. The closed-loop configuration with a magnetic core and a feedback winding in the sensor improved the sensitivity of the sensor, eliminated the offset and drift related to temperature, and greatly reduced the error caused by magnetic hysteresis phenomenon. It can measure currents up to 20 A, with an accuracy of 0.5%, and a 50 kHz small signal bandwidth. [ABSTRACT FROM PUBLISHER]

This paper presents a new concept of magnetic field sensor, employing a magnetostrictive active material and a strain sensor based on a fiber Bragg grating (FBG). The integration of the FBG with the magnetostrictive alloy, allows the transduction of the field signal into a wavelength shift of the FBG. Such an approach allows reliable and multipoint measurements also in harsh environments. Unlike a similar approach [6], the proposed concept sensor employ a Fe-Ga alloy (Galfenol), presenting better performances in terms of rate-independent memory effects (hysteresis) and this would avoid complex procedures for the field reconstruction. Moreover, the possibility to produce samples with frozen prestress in the material, would also allow a better tailoring of the active material with respect to the required sensor characteristics. [ABSTRACT FROM AUTHOR]

Geometric or magnetic asymmetries in synthetic antiferromagnetic particles give rise to ferrimagnetic-like magnetization behavior, both quasi-static and dynamic. Such asymmetries in synthetic ferrimagnets can originate from a thickness imbalance or a fringing field from the reference layer in a nanopillar stack. In this paper, we theoretically describe the effects of the corresponding magnetic asymmetry contribution on the structure’s static and spin-dynamic behavior. The developed model is then used to experimentally determine the asymmetry parameters of typical nanoscale spin-flop junctions, as well as successfully describe their microwave resonant properties, such as the frequency splitting and the field dependence of the optical spin-resonance spectra. [ABSTRACT FROM AUTHOR]

This paper deals with the fundamental theoretical background of a 1-D parametric magneto-dynamic (PMD) model, which analytically solves the interdependence of the magnetic field and macroscopic eddy currents inside a thin soft magnetic steel sheet (SMSS). Furthermore, the loss calculation using the discussed model is presented, where instantaneous powers due to static hysteresis and induced eddy currents, as well as their power loss distributions across the SMSS thickness are calculated. The calculated results are validated by measurements on a non-oriented SMSS using sinusoidal excitations within wide frequency and magnetic flux density ranges. [ABSTRACT FROM AUTHOR]

In this paper, a fast H(M) magnetostatic hysteresis model is presented, tested, and used in Simulink and partial element equivalent circuit (PEEC) environments. The model is primarily designed to achieve full compatibility with the current 3-D PEEC formalism for nonlinear isotropic magnetic materials, compatibility not met by any direct model. The capabilities of the proposed model are shown in stand-alone configuration and as a core of circuit components within the Simulink environment. Its effectiveness in the 3-D PEEC formulation is then demonstrated. [ABSTRACT FROM AUTHOR]

Fe-based amorphous thin films of two compositions (Fe80B20 and Fe65.6Co9.4B25) were deposited by RF magnetron sputtering with and without applying an in situ magnetic field along the films’ in-plane direction. In addition, films with varying thickness were deposited for each composition. Hysteresis loops and residual stress were measured and compared to study the effect of in situ fields on the magnetic and magnetostrictive behavior of the films. Results showed that in situ magnetic fields can lower the in-plane coercivity for the Fe80B20 films. Also, when the residual stress was below a certain level, its distribution in different directions shows a uniaxial feature due to the applied in situ field. This uniaxial distribution of stress adds an extra magnetoelastic anisotropy to the films. This paper provides insight for optimizing magnetic thin films’ properties for applications where the magnetostriction is relevant, in terms of the in situ magnetic field, coercivity, and residual stress. [ABSTRACT FROM PUBLISHER]

An analysis method for characteristics calculation of electric machines is proposed in order to take the effects of eddy currents and hysteresis phenomenon in laminated cores into account. In the proposed method, both the effects of eddy currents and hysteresis phenomenon are expressed as reaction magnetic fields against the exciting field. These fields are determined by coupling the main electromagnetic field analysis that neglects the detailed structures of laminated cores, and 1-D time-stepping analysis along the thickness of electrical steel sheets. The validity of this coupling is confirmed by comparing the measured and calculated results of the core-material characteristics. The effects of the reaction field on the torque characteristics of rotating machines are also clarified. [ABSTRACT FROM AUTHOR]

This paper is devoted to the study of magnetocaloric effect (MCE) in Ni-Mn-In-Co Heusler alloys by direct methods in high magnetic fields. Ni-Mn-In-Co Heusler alloys demonstrate the inverse MCE in the magnetostructural transition area. The adiabatic temperature change value ( \Delta T\mathrm {ad} ) is determined by direct extraction method in magnetic fields up to 10 T. It is shown that the value of \Delta T\mathrm {ad} increases with decrease in the difference between the temperature of magnetostructural transition and the Curie point temperatures of the compounds. The amount of isothermal heat emission (sorption) for Ni43Mn37.8In12.2Co7 alloy is determined as a result of magnetization in magnetic field up to 10 T in the magnetostructural transition area. The obtained results are discussed from the viewpoint of magnetic and lattice subsystems influences on the total entropy change ( \Delta St ). [ABSTRACT FROM AUTHOR]

Magnetic shape memory alloys (MSMAs), which are a class of innovative functional materials, are used as the actuators to be applied widely in high-precision positioning. However, the hysteresis nonlinearity in the MSMA seriously affects the precision positioning of the MSMA-based actuator. In this paper, to study the hysteresis nonlinearity in the MSMA, the Krasnosel’skii–Pokrovskii (KP) model is employed to describe the hysteresis nonlinearity in the MSMA-based actuator, and the density function of the KP model is identified by the Elman neural network. The simulations show that the modeling error rate of the KP model using the Elman neural network is 0.81%, which is reduced by 63.5% compared with that of the KP model based on a recursive least-squares method. This result demonstrates that the KP model based on the Elman neural network can accurately describe the hysteresis nonlinearity in the MSMA-based actuator. [ABSTRACT FROM AUTHOR]

A miniature tri-axis magnetometer with in-plane giant magnetoresistance (GMR) sensors and a fluxguide was designed, implemented, and characterized in this paper. Three GMR sensor dies were aligned on a printed circuit board with their sensing directions in the same plane. By using the flux bending effect of a fluxguide, the magnetic field components in the mounting plane of GMR sensors were generated, and hence, the effective sensing directions are not in the same plane. The tilt of effective sensing direction from the mounting plane allows the device to detect the out-of-plane field component. When the device was used as an electronic compass, the digitally demodulated sensor outputs were converted into the orthogonal geomagnetic field components by using a real-time conversion process with the voltage-to-field transfer matrix. The result shows that the device is suitable for compass application. Further works to implement the similar design on a CMOS chip with integrated GMR elements and a planar modulation coil will realize a compact and easy-to-fabricate tri-axis magnetic field sensor. [ABSTRACT FROM AUTHOR]

This paper presents an improved identification algorithm of the scalar play model, and suggests a novel vector play model to describe the vector hysteretic behavior of a nonoriented electrical steel sheet (ESS) under rotating magnetic fields. The proposed identification algorithm gives much better numerical accuracy than a conventional one by assigning more play operators than the measured asymmetric minor loops. The vector-shape function of the suggested vector play model consists of two scalar shape functions, which are independently identified by using measured hysteresis loops under alternating magnetic fields along rolling and transverse direction of ESS, respectively. The vector play model, furthermore, employs a nonlinear coefficient, which is a function of the magnitude and direction of magnetic flux density, to increase the numerical accuracy. The validity of the suggested vector play model is verified by comparing it with experimental results under various magnetic-field conditions. [ABSTRACT FROM AUTHOR]

This paper presents numerical procedures for the treatment of tensors related to the vector Jiles–Atherton (JA) model applied to the finite element method (FEM). The method is based on the 3-D differential permeability formulation. A more precise calculation implies the determination of the off-diagonal terms of tensor parameters. The main goal is to verify if such a change improves the convergence stability of the model coupled with FEM and if the use of the JA off-diagonal terms yields a more accurate hysteresis representation. We present results comparing experimental data of the Testing Electromagnetic Analysis Methods problem 32 with the proposed method. [ABSTRACT FROM AUTHOR]

In this paper, we introduce a novel approach for obtaining steady-state solutions in time-periodic magnetic field analyses considering hysteresis. First, we extract the poorly converged error component in transient calculations using the parallel time-periodic explicit-error correction method. Then, tentative steady-state solutions are obtained for each element by correcting the extracted error components. Based on the tentative periodic waveforms of the flux density vectors, the magnetization history of each element is also corrected. Numerical results are presented to demonstrate the effectiveness of the developed approach. [ABSTRACT FROM AUTHOR]

The nondestructive evaluation of the opposite side defects of the steel wall in the petrochemical plant is necessary for safe maintenance. Generally, the alternating magnetic flux leakage testing (AMT) is used for detecting only the surface defect of the steel wall. In this paper, electromagnetic nondestructive inspection method for the detecting of the opposite side defect in the steel plate using this AMT method by applying the residual magnetism is investigated. The synthetic magnetic field of both residual magnetism and alternating magnetic field is estimated by the 3-D nonlinear finite element method taking account of the hysteresis and minor loop characteristics of the steel plate. [ABSTRACT FROM AUTHOR]

Magnetically driven micromachines play an essential role in a number of biomedical and other remote control applications. In this paper, a magnetically driven robot composed of customized UV-curable resin was fabricated by (3-D) printing via initiator-triggered radical polymerization and the subsequent polyelectrolyte-brush-assisted electroless plating. A layer of magnetic material was grown in situ on the 3-D printed structure, which exhibited soft-magnetic properties proved by the vibrating sample magnetometer measurement. The magnetic robot was successfully actuated under the rotating magnetic field produced from a manipulator of permanent magnet. By utilizing the spiral structure, the 3-D robot was designed to translate rotational movement into linear motion. A comprehensive investigation was also carried out on the optimization of spiral shape, liquid viscosity and the strategy of magnetic controlling. The remote controlling experiments demonstrate that this initiator-integrated 3-D printing is an effective technique for making magnetically driven objects. [ABSTRACT FROM AUTHOR]

This paper mainly explores the influence of bending stresses on the magnetic characteristics of three-phase amorphous transformers. Different types of core structures, including C-shaped and toroidal cores, are considered for a comparison of magnetic properties using VSM, XRD, and SEM. Among all specimens, those taken from the limb plane and the rectangular corner of a C-core have the lowest and highest coercivities, respectively. In addition, the crystalline property of Fe and \alpha-Fe of rectangular cores is stronger than that of toroidal cores. Subsequently, the properties of magnetic loss and magnetic anisotropy are investigated. The experimental results of three-phase amorphous core transformers with a capacity of 100 kVA demonstrate that the toroidal core transformer has better magnetic characteristics in terms of lower core loss and exciting power than conventional C-core transformers. [ABSTRACT FROM AUTHOR]

This paper presents results of iron-loss evaluation of an induction motor model core by using the finite element method considering two-dimensional vector magnetic properties. We propose a new iron-loss calculation method considering higher harmonic components of the flux density waveforms caused by the secondary slot ripples. Influence of the harmonic components on the total iron loss is clarified numerically. In addition, reduction of rotational iron losses is investigated by making holes at the tooth base parts. The results show that the rotational magnetic flux distribution is effectively controlled by making holes. In this paper, obtained knowledge about iron-loss control with holes in the stator core is presented and discussed. [ABSTRACT FROM PUBLISHER]

This paper deals with the mathematical definition of a general vector hysteresis operator in 3-D, as an extension of previous papers where the theory has been limited to the 2-D case. Although the paper is mainly focused on magnetic hysteresis, the definitions and the results reported can be applied to any general physical phenomenon that exhibits hysteresis. We show here the main general properties of the general hysteresis operator in 3-D. [ABSTRACT FROM AUTHOR]