Magnetochemistry

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2 pages, 156 KiB

Open AccessEditorial

Special Issue: Advances in Computational Electromagnetics

by Valerio De Santis

Magnetochemistry 2021, 7(6), 89; https://doi.org/10.3390/magnetochemistry7060089 - 21 Jun 2021

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Abstract

Recent advances in computational electromagnetics (CEMs) have made the full characterization of complex magnetic materials possible, such as superconducting materials, composite or nanomaterials, rare-earth free permanent magnets, etc [...] Full article

(This article belongs to the Special Issue Advances in Computational Electromagnetics)

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22 pages, 6117 KiB

Open AccessArticle

Oscillatory Copper Deposition on Conical Iron Electrodes in a Nonuniform Magnetic Field

by Giovanni Marinaro, Mengyuan Huang, Gerd Mutschke, Xuegeng Yang and Kerstin Eckert

Magnetochemistry 2021, 7(4), 46; https://doi.org/10.3390/magnetochemistry7040046 - 28 Mar 2021

Cited by 5 | Viewed by 2391

Abstract

We report the effect of a magnetic field on the deposition of copper ions on a conically shaped iron probe. In our setup, the magnetic forces and buoyancy are the key factors influencing the electrolyte flow and the mass transfer. Without external current, [...] Read more.

We report the effect of a magnetic field on the deposition of copper ions on a conically shaped iron probe. In our setup, the magnetic forces and buoyancy are the key factors influencing the electrolyte flow and the mass transfer. Without external current, a spontaneous reduction of copper on the iron cone occurs, known as electroless deposition. Mach–Zehnder and differential interferometry indicate a variation in the concentration of copper ions near the cone. After an initial transient of about 60 s, temporal oscillations in the copper concentration are found under the effect of a magnetic field. In galvanostatic conditions, a similar oscillatory behavior of the concentration of the electrolyte is observed. Numerical simulations show that the oscillations are caused by the magnetic gradient, Lorentz force, and buoyancy force counteracting one another, and the oscillation frequency is estimated analytically based on this mechanism. Furthermore, we present a study on the oscillation frequency for both electroless and galvanostatic conditions with different current densities. The results of this study may stimulate future research aimed at the local control of the deposition rate and the realization of miniaturized, regularly structured deposits using magnetic fields. Full article

(This article belongs to the Special Issue Advances in Computational Electromagnetics)

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11 pages, 1915 KiB

Open AccessArticle

Numerical Computation and Analysis of Electromagnetic Field in Magnetic Suspension and Balance System

by Mingda Zhai, Wentao Xia, Zhiqiang Long and Fengshan Dou

Magnetochemistry 2021, 7(3), 33; https://doi.org/10.3390/magnetochemistry7030033 - 26 Feb 2021

Cited by 1 | Viewed by 2409

Abstract

The magnetic suspension wind tunnel balance (MSBS) is an entirely new device for aerodynamic measurement, and it makes the best of the electromagnetic force to suspend the aircraft model in the wind tunnel without contact. Compared with conventional wind tunnel balance, it absolutely [...] Read more.

The magnetic suspension wind tunnel balance (MSBS) is an entirely new device for aerodynamic measurement, and it makes the best of the electromagnetic force to suspend the aircraft model in the wind tunnel without contact. Compared with conventional wind tunnel balance, it absolutely abandons the model support and airflow interference. Therefore, the aerodynamic measurement environment is more authentic and the aerodynamic measurement results are more accurate. The electromagnetic field in MSBS plays a major role in bearing the force of wind. The numerical computation and finite element numerical analysis are performed to investigate key factors of electromagnetic force under different conditions. The calculation results based on finite element method (FEM) have revealed that the diameter and the spacing of of the axial coil, the number of segments and the pitch angle of the suspension model are key factors of electromagnetic force. Based on the above key factors, the structure of the magnetic suspension balance is optimized to maximize the electromagnetic force under multiple constraints. Full article

(This article belongs to the Special Issue Advances in Computational Electromagnetics)

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11 pages, 3475 KiB

Open AccessArticle

Chassis Influence on the Exposure Assessment of a Compact EV during WPT Recharging Operations

by Valerio De Santis, Luca Giaccone and Fabio Freschi

Magnetochemistry 2021, 7(2), 25; https://doi.org/10.3390/magnetochemistry7020025 - 7 Feb 2021

Cited by 9 | Viewed by 2052

Abstract

In this study, the external magnetic field emitted by a wireless power transfer (WPT) system and the internal electric field induced in human body models during recharging operations of a compact electric vehicle (EV) are evaluated. The magneticfield is calculated with a hybrid [...] Read more.

In this study, the external magnetic field emitted by a wireless power transfer (WPT) system and the internal electric field induced in human body models during recharging operations of a compact electric vehicle (EV) are evaluated. The magneticfield is calculated with a hybrid scheme coupling the boundary element method with the surface impedance boundary conditions in order to fit the multiscale open-boundary characteristics of the problem. A commercial software is then used to perform numerical dosimetry. Specifically, two realistic anatomical models, both in a driving position and in a standing posture, are considered, and the chassis of the EV is modeled either as a currently employed aluminum alloy and as a futuristic carbon fiber composite panel. Aligned and misaligned coil configurations of the WPT system are considered as well. The analysis of the obtained results shows that the International Commission on Non-Ionizing Radiation Protection (ICNIRP) reference levels are exceeded in the driving position, especially for the carbon fiber chassis, whereas the system is compliant with the basic restrictions, at least for the considered scenarios. Full article

(This article belongs to the Special Issue Advances in Computational Electromagnetics)

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11 pages, 5701 KiB

Open AccessFeature PaperArticle

Identification of Material Properties and Optimal Design of Magnetically Shielded Rooms

by Aldo Canova, Fabio Freschi, Luca Giaccone, Maurizio Repetto and Luigi Solimene

Magnetochemistry 2021, 7(2), 23; https://doi.org/10.3390/magnetochemistry7020023 - 6 Feb 2021

Cited by 6 | Viewed by 2274

Abstract

In this paper, we propose an optimal design procedure for magnetically shielded rooms. Focusing on multi-layer ferromagnetic structures, where inner layers operate at very low magnetic field, we propose an identification method of the magnetic material characteristic in the Rayleigh region. A numerical [...] Read more.

In this paper, we propose an optimal design procedure for magnetically shielded rooms. Focusing on multi-layer ferromagnetic structures, where inner layers operate at very low magnetic field, we propose an identification method of the magnetic material characteristic in the Rayleigh region. A numerical model to simulate the shielding efficiency of a multi-layer ferromagnetic structure is presented and experimentally tested on different geometries and layer configurations. The fixed point iterative method is adopted to handle the nonlinearity of the magnetic material. In conclusion, the optimization of the design parameters of a MSR is discussed, using the Vector Immune System algorithm to minimize the magnetic field inside the room and the cost of the structure. The results highlight that a linear magnetic characteristic for the material is sufficient to identify the suitable geometry of the shield, but the nonlinear model in the Rayleigh region is of fundamental importance to determine a realistic shielding factor. Full article

(This article belongs to the Special Issue Advances in Computational Electromagnetics)

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16 pages, 5207 KiB

Open AccessFeature PaperArticle

Vector Hysteresis Processes for Innovative Fe-Si Magnetic Powder Cores: Experiments and Neural Network Modeling

by Simone Quondam Antonio, Francesco Riganti Fulginei, Antonio Faba, Francesco Chilosi and Ermanno Cardelli

Magnetochemistry 2021, 7(2), 18; https://doi.org/10.3390/magnetochemistry7020018 - 24 Jan 2021

Cited by 6 | Viewed by 1857

Abstract

A thorough investigation of the 2-D hysteresis processes under arbitrary excitations was carried out for a specimen of innovative Fe-Si magnetic powder material. The vector experimental measurements were first performed via a single disk tester (SDT) apparatus under a controlled magnetic induction field, [...] Read more.

A thorough investigation of the 2-D hysteresis processes under arbitrary excitations was carried out for a specimen of innovative Fe-Si magnetic powder material. The vector experimental measurements were first performed via a single disk tester (SDT) apparatus under a controlled magnetic induction field, taking into account circular, elliptic, and scalar processes. The experimental data relative to the circular loops were utilized to identify a vector model of hysteresis based on feedforward neural networks (NNs), having as an input the magnetic induction vector B and as an output the magnetic field vector H. Then the model was validated by the simulation of the other experimental hysteresis processes. The comparison between calculated and measured loops evidenced the capability of the model in both the reconstruction of the magnetic field trajectory and the prediction of the power loss under various excitation waveforms. Finally, the computational efficiency of the model makes it suitable for future application in finite element analysis (FEA). Full article

(This article belongs to the Special Issue Advances in Computational Electromagnetics)

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12 pages, 2287 KiB

Open AccessArticle

A Novel Computational Method to Identify/Analyze Hysteresis Loops of Hard Magnetic Materials

by Alessandro Giuseppe D’Aloia, Antonio Di Francesco and Valerio De Santis

Magnetochemistry 2021, 7(1), 10; https://doi.org/10.3390/magnetochemistry7010010 - 7 Jan 2021

Cited by 6 | Viewed by 3069

Abstract

In this study, a novel computational method capable of reproducing hysteresis loops of hard magnetic materials is proposed. It is conceptually based on the classical Preisach model but has a completely different approach in the modeling of the hysteron effect. Indeed, the change [...] Read more.

In this study, a novel computational method capable of reproducing hysteresis loops of hard magnetic materials is proposed. It is conceptually based on the classical Preisach model but has a completely different approach in the modeling of the hysteron effect. Indeed, the change in magnetization caused by a single hysteron is compared here to the change in velocity of two disk-shaped solids elastically colliding with each other rather than the effect of ideal geometrical entities giving rise to so-called Barkhausen jumps. This allowed us to obtain a simple differential formulation for the global magnetization equation with a significant improvement in terms of computational performance. A sensitivity analysis on the parameters of the proposed method has indeed shown the capability to model a large class of hysteresis loops. Moreover, the proposed method permits modeling of the temperature effect on magnetization of neodymium magnets, which is a key point for the design of electrical machines. Therefore, application of the proposed method to the hysteresis loop of a real NdFeB magnet has been proven to be very accurate and efficient for a large temperature range. Full article

(This article belongs to the Special Issue Advances in Computational Electromagnetics)

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19 pages, 4285 KiB

Open AccessFeature PaperArticle

The Microstructural Model of the Ferromagnetic Material Behavior in an External Magnetic Field

by Anatoli A. Rogovoy, Oleg V. Stolbov and Olga S. Stolbova

Magnetochemistry 2021, 7(1), 7; https://doi.org/10.3390/magnetochemistry7010007 - 1 Jan 2021

Cited by 9 | Viewed by 2740

Abstract

In this paper, the behavior of a ferromagnetic material is considered in the framework of microstructural modeling. The equations describing the behavior of such material in the magnetic field, are constructed based on minimization of total magnetic energy with account of limitations imposed [...] Read more.

In this paper, the behavior of a ferromagnetic material is considered in the framework of microstructural modeling. The equations describing the behavior of such material in the magnetic field, are constructed based on minimization of total magnetic energy with account of limitations imposed on the spontaneous magnetization vector and scalar magnetic potential. This conditional extremum problem is reduced to the unconditional extremum problem using the Lagrange multiplier. A variational (weak) formulation is written down and linearization of the obtained equations is carried out. Based on the derived relations a solution of a two-dimensional problem of magnetization of a unit cell (a grain of a polycrystal or a single crystal of a ferromagnetic material) is developed using the finite element method. The appearance of domain walls is demonstrated, their thickness is determined, and the history of their movement and collision is described. The graphs of distributions of the magnetization vector in domains and in domain walls in the external magnetic field directed at different angles to the anisotropy axis are constructed and the magnetization curves for a macrospecimen are plotted. The results obtained in the present paper (the thickness of the domain wall, the formation of a 360-degree wall) are in agreement with the ones available in the current literature. Full article

(This article belongs to the Special Issue Advances in Computational Electromagnetics)

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