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To analyze effectively magnetic shielding effects by shields with fine structure.

Simplification of the fine structure makes it possible to analyze them efficiently. The authors have introduced a homogenization method to estimate effective permeability of magnetic composite structure for the static field. The homogenization method is applied to the analysis of magnetic shields composed of steel plates and steel rods against DC power lines to test its feasibility.

The properties of the magnetic shielding are analyzed by using the homogenization method. The errors of the magnetic fields increase in case of very few layers.

The simplification of the magnetic shields with fine structure by using the homogenization method makes it possible to analyze efficiently magnetic shielding effects, although the accuracy becomes worse in case of very few layers.

The purpose of this paper is to introduce a numerical calculation method to study the uniformity of the magnetic field in a cold crucible used for directional solidification (DS) and provide information for designing a cold crucible that can induce a uniform magnetic field.

To obtain the characteristics of the magnetic field in a cold crucible and its influence on the directional solidification processing, based on experimental verification, 3‐D finite element (FE) models with different crucible configuration‐elements and power parameters were established to study the uniformity of the magnetic field in a cold crucible. In addition, different TiAl ingots were directionally solidified with different cold crucibles, and the solid/liquid (S/L) interfaced were examined to investigate the effect of the magnetic field on the macrostructure of those ingots.

The uniformity of the magnetic field in a given domain can be quantitatively analyzed by statistical methods. Numerical calculation results showed that the uniformity of the magnetic field can be improved by optimizing the crucible configuration and adopting lower frequency. Better uniformity of the magnetic field in a cold crucible is beneficial to directional solidification.

The calculation of the uniformity of the magnetic field is proposed as a method for quantitative study of the distribution characteristics of the magnetic field in a cold crucible. The relationship between the S/L interfaces of TiAl ingots and the uniformity of the magnetic field is initially characterised; additionally, techniques for improving the uniformity of the magnetic field in a cold crucible are suggested.

The purpose of this paper is to reduce computation time of magnetic characteristic analysis considering 2D vector magnetic properties.

The paper proposes a complex E&S modelling with assumption that both flux density and field strength waveforms are sinusoidal. The computation time of the complex E&S modeling becomes 1/10 in comparison with one of the conventional E&S modeling. This modeling is applicable up to 1.4 T of the local magnetic flux density condition in the case of non‐oriented magnetic materials.

In the results of the magnetic field analyses of a linear‐induction motor model core by means of the finite element method taking account of the complex E&S modeling, the distributions of the flux density and the field strength were able to be approximately analyzed and their phase differences in space were represented. The results of the magnetic characteristic analysis of the linear‐induction motor showed that the teeth‐end shape had large influences on the thrust and cogging.

This technique helps to know approximately local vector magnetic properties in core materials. This modeling is very useful for magnetic core design taking account of the simplified 2D vector magnetic properties.

The method presented in this paper enables expression of the simplified 2D vector magnetic properties in magnetic field analyses. The computation time can be considerably reduced in comparison with the conventional method.

Magnetization is one of the most important parameters of magnetic fluids. The shape of the magnetization curve often determines the application of a fluid in a device. On the basis of the magnetization curve, it is also possible to estimate, for example, the distribution and size of the particles in a magnetic fluid carrier fluid. The aim of this paper is to present a new approach for estimating the magnetization curve.

The proposed method is an iterative method based on the measurement of magnetic induction on a test stand. To determine the magnetization curve, a numerical simulation of the magnetic field distributions for the preliminary magnetization curve should also be performed. Numerical simulations for modified forms of the magnetization curve are performed until the difference between the results obtained by the measurement and numerical simulation are the smallest.

This paper presents the results of magnetization curve research for ferrofluids and magnetorheological fluids.

The discussed method shows the possibilities of using numerical simulations of magnetic field distribution to determine the magnetic properties of magnetic fluids. This method may be an alternative for estimating the magnetization curve of the magnetic fluid compared to other methods.

The purpose of this paper is to simulate the flow of a conducting fluid past a circular cylinder placed centrally in a channel subjected to an imposed transverse magnetic field to study the effect of a magnetic field on vortex shedding at different Reynolds numbers varying from 50 to 250.

The two‐dimensional incompressible laminar viscous flow equations are solved using a second‐order implicit unstructured collocated grid finite volume method.

An imposed transverse magnetic field markedly reduces the unsteady lift amplitude indicating a reduction in the strength of the shed vortices. It is observed that the periodic vortex shedding at the higher Reynolds numbers can be completely suppressed if a sufficiently strong magnetic field is imposed. The required magnetic field strength to suppress shedding increases with Reynolds number. The simulation shows that the separated zone behind the cylinder in a steady flow is reduced as the magnetic field strength is increased.

In this paper, due attention is given to resolve and study the unsteady cylinder wake and its interaction with the shear‐layer on the channel wall in the presence of a magnetic field. A critical value of the Hartmann number for complete suppression of the shedding at a given Reynolds number is found.

This paper seeks to present some new designs of sliding bearings lubricated with magnetic fluids (ferrofluids) and the possibility of using them in modern bearing technology, in new computer and audiovisual equipment among others.

The paper presents new designs of journal, thrust and journal‐thrust sliding bearings lubricated and sealed with magnetic fluids such as: magnetic fluid bearing bushing made of magnetizable material, pivot bearings with porous sleeve impregnated with ferrofluid, self‐aligning bearings, hydrodynamic ferrofluid bearings with spiral and herringbone grooves structure are presented. Moreover, examples are shown of applications in modern bearing technology.

The paper provides information about new designs of magnetic fluid sliding bearings assemblies and gives the main advantages of these bearings over conventional ball bearings, such as extremely low non‐repetitive run‐out (high‐accuracy of rotation), good damping and quietness of operation, maintenance free service and high reliability.

This paper offers some new designs of compact, low friction and self‐contained magnetic fluid sliding bearings and points up their practical applications.

The purpose of this paper is to report a numerical solution for the problem of steady, two dimensional boundary layer buoyant flow on a vertical magnetized surface, when both the viscosity and thermal conductivity are assumed to be temperature-dependent. In this case, the motion is governed by a coupled set of three nonlinear partial differential equations, which are solved numerically by using the finite difference method (FDM) by introducing the primitive variable formulation. Calculations of the coupled equations are performed to investigate the effects of the different governing parameters on the profiles of velocity, temperature and the transverse component of magnetic field. The effects of the thermal conductivity variation parameter, viscosity variation parameter, magnetic Prandtl number Pm_r, magnetic force parameter S, mixed convection parameter Ri and the Prandtl number Pr on the flow structure and heat transfer characteristics are also examined.

FDM.

It is noted that when the Prandtl number Pr is sufficiently large, i.e. Pr=100, the buoyancy force that driven the fluid motion is decreased that decrease the momentum boundary layer and there is no change in thermal boundary layer is noticed. It is also noted that due to slow motion of the fluid the magnetic current generates which increase the magnetic boundary layer thickness at the surface. It is observed that the momentum boundary layer thickness is increased, thermal and magnetic field boundary layers are decreased with the increase of thermal conductivity variation parameter =100. The maximum boundary layer thickness is increased for =100 and there is no change seen in the case of thermal boundary layer thickness but magnetic field boundary layer is deceased. The momentum boundary layer thickness shoot quickly for =40 but is very smooth for =50.There is no change is seen for the case of thermal boundary layer and very clear decay for =40 is noted.

This work is original research work.

The paper presents a method of creating electrical equivalent diagrams of magnetic circuits. The method is based on bond‐graph techniques, using flux derivative as flow variable. Couplings between magnetic and electric part of the system are represented by gyrators. Simple models of magnetic branches, including non‐linear effects due to saturation, hysteresis and eddy currents, are presented. These models can be easily combined into magnetic circuit models, which can be transformed into dual electric equivalent circuit. Various equivalent circuits of transformers are discussed. The proposed models are simple and particularly useful for system‐level simulation of power electronic and motion control systems with magnetic elements. These models can be easily developed if needed. Theoretical considerations are illustrated by examples of digital simulation and experimental results.

The purpose of this paper is to propose a magnetic‐geared motor with permanent magnets only on the high‐speed rotor as a solution to the problems of magnetic gears. Magnetic gears have some advantages such as no mechanical loss and maintenance‐free operation that are not observed in conventional mechanical gears. Furthermore, they have inherent overload protection. A novel structure which the magnetic gear is integrated with the brushless motor (magnetic‐geared motor) was proposed by Atallah et al. This magnetic‐geared motor is based on the magnetic gear which consists of a high‐ and low‐speed rotor, and a stator. Although this magnetic‐geared motor has a high‐torque density, problems with manufacturing and cost exist because multi‐pole permanent magnets are mounted on the high‐speed rotor and stator.

A magnetic‐geared motor with permanent magnets only on the high‐speed rotor was proposed and its operational principle was described. The cogging torque characteristics were mathematically formulated and the authors ascertained that the cogging torque contains components of multiples of 60th order. In order to verify the order of the cogging torque, the 3‐D finite element method analysis was conducted and measurements on a prototype were carried out.

The 60th component and its multiples were observed in the computed and measured cogging torque waveform. However, the cogging torque characteristics, especially the order of the cogging torque on the low‐speed rotor, have not been clarified.

In the near future, cogging torque reduction methods will be proposed, and verified by conducting 3‐D FEM analyses and carrying out measurements on a prototype. Furthermore, the torque characteristics when an electrical current is applied to the coils and the eddy‐current loss characteristics will be verified.

In many different engineering fields often there is a need to protect regions from electromagnetic interference. According to static and low-frequency magnetic fields the common strategy bases on using a shield made of conductive or ferromagnetic material. Another screening technique uses solenoids that generate an opposite magnetic field to the external one. The purpose of this paper is to discuss the shielding effect for a magnetic and conducting cylindrical screen rotating in an external static magnetic field.

The magnetic flux density is expressed in terms of the magnetic vector potential. Applying the separation of variables method analytical solutions are obtained for an infinitely long magnetic conducting cylindrical screen rotating in a uniform static transverse magnetic field.

Analytical formulas of the shielding factor for a cylindrical screen of arbitrary conductivity and magnetic permeability are given. A magnetic Reynolds number is found to be an appropriate indication of the change in magnetic field inside the screen. Useful simplified expressions are presented.

This paper treats in a qualitative way the possibility of static magnetic field shielding by using rotating conducting magnetic cylindrical screens. Analytical solutions are given. If the angular velocity is equal to zero or the relative permeability of the shield is equal to one the shielding factor has forms well known from literature.