Phenomenological Interpretation of Classical Expression for Force Affecting a Ferroparticle in the Magnetic Field

2014 ◽  
Vol 595 ◽  
pp. 70-75
Author(s):  
Anna Sandulyak ◽  
Alexander Sandulyak ◽  
Vera Ershova ◽  
Alexander Snedkov ◽  
Darya Sandulyak
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
Magnetic Separation ◽  
Magnetic Induction ◽  
Magnetic Force ◽  
Magnetic Gradient ◽  
Polar Surface ◽  
Magnetic Elements ◽  
Classical Expression ◽  
Force Impact

The unprecedented attempt has been made to fully expand classical and often quoted (above all by magnetic separation regimes and conditions analysis) expression for the force affecting the ferroparticle in magnetic field with the functional character of the following parameters of this expression being taken into account: magnetic induction, magnetic gradient and ferroparticle magnetic susceptibility. For this purpose a particular case of force impact has been analyzed in field approximating one-dimensional field. This field is produced in module of two distantly oriented magnetic elements. The obtained dependences for magnetic induction, magnetic gradient and ferroparticle magnetic susceptibility (according to distance x to polar surface one of the magnetic elements) have been used. By the analysis the fact has been taken into account that ferroparticle magnetic susceptibility depends on its shape as well as substance magnetic susceptibility depends, in its turn, on magnetic field intensity around ferroparticle. In other words, magnetic susceptibility of material depends on distance x to polar surface usually being ignored. The analysis of the following expanded variant of magnetic force expression allows to determine that phenomenological dependence (on parameter x) which has a very simple exponential form can be an alternative to this expression. Such dependence can be reasonably used by decision-making in theoretical and practical tasks of magnetic separation. The undertaken attempt to specify the role of another parameter B0 – magnetic induction on polar surface (that is often considered as the most essential) – shows the power (approximating square) character of magnetic force concerning this parameter.

scholarly journals The Effect of Roasting Temperature on Ilmenite Particle Rotation Characteristics in a Rotating Magnetic Field

2003 ◽  
Vol 12 (3) ◽  
pp. 133-143
Author(s):  
N. R. Allen
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
Rotating Magnetic Field ◽  
Magnetic Rotation ◽  
Particle Rotation ◽  
Particle Measurements ◽  
The Earth ◽  
Magnetic Elements ◽  
Force Increase ◽  
Roasting Temperature

Individual ilmenite particle measurements of magnetic susceptibility and magnetic rotation index show that, as ilmenite roast temperatures increase, both the magnetic anisotropy and the coercive force increase. By around 650°C the particles are behaving magnetically, in magnetic fields up to 0.3 T as though they contain magnetic elements with a single unidirectional magnetic axis.The presence of some magnetic field, even that of the earth, during the cooling of ilmenite samples roasted above 500°C may be essential to the magnetising roast process.

scholarly journals Rayleigh-Bénard Convection of Paramagnetic Liquid under a Magnetic Field from Permanent Magnets

Symmetry ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 341
Author(s):  
Kengo Wada ◽  
Masayuki Kaneda ◽  
Kazuhiko Suga
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Magnetic Induction ◽  
Magnetic Force ◽  
Permanent Magnets ◽  
Cell Pattern ◽  
Benard Convection ◽  
Rayleigh Benard Convection ◽  
Rayleigh Benard ◽  
High Magnetic Induction

The convection control is important in terms of the heat transfer enhancement and improvement of the applied devices and resultant products. In this study, the convection control by a magnetic field from block permanent magnets is numerically investigated on the Rayleigh-Bénard convection of paramagnetic fluid. To enhance the magnetic force from the available permanent magnets, pairs of alternating-pole magnets are employed and aligned near the bottom heated wall. The lattice Boltzmann method is employed for the computation of the heat and fluid flow with the consideration of buoyancy and magnetothermal force on the working fluid. It is found that, since the magnetic force at the junction of pair magnets becomes strong remarkably and in the same direction as the gravity, descending convection flow is locally enhanced and the pair of symmetrical roll cells near the magnet junction becomes longitudinal. The local heat transfer corresponds to the affected roll cell pattern; locally enhanced at the magnet junctions and low heat transfer area is shifted aside the magnet outer edge. The averaged Nusselt number on the hot wall also increases proportionally to the magnetic induction but it is saturated at high magnetic induction. This suggests the roll cell pattern is no more largely affected at extremely-high magnetic induction.

A modified magnetic force model and experimental validation of a tri-stable piezoelectric energy harvester

2020 ◽  
Vol 31 (7) ◽  
pp. 967-979 ◽  
Author(s):  
Guangqing Wang ◽  
Haiqiang Wu ◽  
Wei-Hsin Liao ◽  
Sujuan Cui ◽  
Zexiang Zhao ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Separation ◽  
Magnetic Dipole ◽  
Magnetic Force ◽  
Energy Harvester ◽  
Separation Distance ◽  
Force Model ◽  
Point Dipole ◽  
Transition Mechanism ◽  
Piezoelectric Energy

Nonlinear tri-stable piezoelectric energy harvesters with magnetic field coupling have attracted many researchers’ interest in ambient vibration energy harvesting and conversion. In such a tri-stable piezoelectric energy harvester, the nonlinear magnetic force generated by the external magnetic field is mainly calculated by the equivalent magnetic dipole method. However, this method will give highly erroneous results when the magnetic separation distance is small. This study presents a modified magnetic force model to precisely calculate the nonlinear magnetic force exerted on the tip of the cantilever beam. Unlike the equivalent magnetic dipole method regarding the magnet as a point dipole at its body center, this model only considers the surface magnetization current of the left and right surfaces of the magnets and replaced them by the one of the center point dipoles on these associated surfaces. With this model, the nonlinear magnetic force, the potential energy, and the transition mechanism of the tri-stable piezoelectric energy harvester are numerically investigated. Experimental validations are consequently performed to testify the numerical results. Compared with the equivalent magnetic dipole method, the modified magnetic force model has a much higher accuracy to be more applicable for different magnetic separation distances, especially when the magnetic separation distance is small.

Effect of Rod Arrangement in Matrix on High Gradient Magnetic Separation Performance

2013 ◽  
Vol 634-638 ◽  
pp. 3351-3354 ◽  
Author(s):  
Lu Zheng Chen ◽  
Guo Dong Xu ◽  
Shu Ming Wen ◽  
Si Qing Liu ◽  
Li Kun Gao
Keyword(s):  
Magnetic Separation ◽  
Magnetic Induction ◽  
Pilot Scale ◽  
Superior Performance ◽  
Separation Performance ◽  
Collision Efficiency ◽  
High Gradient Magnetic Separation ◽  
High Gradient ◽  
Magnetic Elements ◽  
The Matrix

The effect of rod arrangement in a rod matrix on high gradient magnetic separation (HGMS) performance has been comparatively investigated through a cyclic pilot-scale centrifugal HGMS separator, with contiguously and orthogonally arranged rod matrixes respectively. The results of investigation indicate that the arrangement of rod elements in the matrix has a distinct effect on the HGMS performance, for relatively low magnetic inductions; beyond the threshold magnetic induction, the magnetic induction dominates that of the arrangement and the importance of the arrangement is significantly weakened even vanished. It was thus concluded that the combinatorial optimization for magnetic elements in the matrix improves the collision efficiency of particles with matrix, and gives a superior performance in a HGMS separator, at a lower energizing consumption.

scholarly journals The Applicability of Davis Tube Tests to Ore Separation by Drum Magnetic Separators

2003 ◽  
Vol 12 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Vasile Murariu ◽  
Jan Svoboda
Keyword(s):  
Magnetic Field ◽  
Rare Earth ◽  
Field Strength ◽  
Magnetic Induction ◽  
Magnetic Force ◽  
Current Practice ◽  
Magnetic Separator ◽  
Operating Field ◽  
Correct Information ◽  
The Magnetic Field

The current practice of assessing the efficiency of recovery of magnetite and ferrosilicon by drum magnetic separators is to conduct Davis tube tests at a magnetic induction equal to that on the surface of the drum. It is, however, the magnetic force or the force index, and not the magnetic field strength, that are decisive in the operation of a magneticseparator. Since the magneticfield gradients generated by Davis tube and drum magnetic separators are generally different, it is unlikely that the above practice would yield correct information. This article analyses the patterns of the force index generated by drum magnetic separators and a Davis tube operated at different field strengths. It is shown that in order to obtain a correct assessment of the efficiency of separation by a ferrite drum magnetic separator, a Davis tube should be operated at the field of about 0.1 T, which is lower than the current practice suggests. For a rare-earth drum separator the Davis tube operating field should be at least 0.3 T.

Analysis of magneto rheological elastomers for energy harvesting systems

2020 ◽  
Vol 64 (1-4) ◽  
pp. 439-446
Author(s):  
Gildas Diguet ◽  
Gael Sebald ◽  
Masami Nakano ◽  
Mickaël Lallart ◽  
Jean-Yves Cavaillé
Keyword(s):  
Magnetic Field ◽  
Energy Harvesting ◽  
Shear Strain ◽  
Magnetic Induction ◽  
Magnetic Particles ◽  
Homogeneous Magnetic Field ◽  
Electrical Signal ◽  
Harvesting Systems ◽  
Dc Bias ◽  
Magneto Rheological

Magneto Rheological Elastomers (MREs) are composite materials based on an elastomer filled by magnetic particles. Anisotropic MRE can be easily manufactured by curing the material under homogeneous magnetic field which creates column of particles. The magnetic and elastic properties are actually coupled making these MREs suitable for energy conversion. From these remarkable properties, an energy harvesting device is considered through the application of a DC bias magnetic induction on two MREs as a metal piece is applying an AC shear strain on them. Such strain therefore changes the permeabilities of the elastomers, hence generating an AC magnetic induction which can be converted into AC electrical signal with the help of a coil. The device is simulated with a Finite Element Method software to examine the effect of the MRE parameters, the DC bias magnetic induction and applied shear strain (amplitude and frequency) on the resulting electrical signal.

An Augmented Iteratively Re-weighted and Refined Least Squares Method for lp Minimization Problem in Inverse Modeling of Potential Field Magnetic Data

2020 ◽  
Vol 1 (3) ◽  
Author(s):  
Maysam Abedi
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
Least Squares ◽  
Minimization Problem ◽  
Potential Field ◽  
Field Data ◽  
Least Squares Method ◽  
Porphyry Copper ◽  
Magnetic Data ◽  
Magnetic Field Data

The presented work examines application of an Augmented Iteratively Re-weighted and Refined Least Squares method (AIRRLS) to construct a 3D magnetic susceptibility property from potential field magnetic anomalies. This algorithm replaces an lp minimization problem by a sequence of weighted linear systems in which the retrieved magnetic susceptibility model is successively converged to an optimum solution, while the regularization parameter is the stopping iteration numbers. To avoid the natural tendency of causative magnetic sources to concentrate at shallow depth, a prior depth weighting function is incorporated in the original formulation of the objective function. The speed of lp minimization problem is increased by inserting a pre-conditioner conjugate gradient method (PCCG) to solve the central system of equation in cases of large scale magnetic field data. It is assumed that there is no remanent magnetization since this study focuses on inversion of a geological structure with low magnetic susceptibility property. The method is applied on a multi-source noise-corrupted synthetic magnetic field data to demonstrate its suitability for 3D inversion, and then is applied to a real data pertaining to a geologically plausible porphyry copper unit.  The real case study located in  Semnan province of  Iran  consists  of  an arc-shaped  porphyry  andesite  covered  by  sedimentary  units  which  may  have  potential  of  mineral  occurrences, especially  porphyry copper. It is demonstrated that such structure extends down at depth, and consequently exploratory drilling is highly recommended for acquiring more pieces of information about its potential for ore-bearing mineralization.

Study of MFM Application in Semiconductor Failure Analysis

2004 ◽  
Author(s):  
Way-Jam Chen ◽  
Lily Shiau ◽  
Ming-Ching Huang ◽  
Chia-Hsing Chao
Keyword(s):  
Magnetic Field ◽  
Failure Analysis ◽  
Magnetic Force Microscopy ◽  
Magnetic Force ◽  
Current Flow ◽  
Force Microscopy ◽  
The Magnetic Field ◽  
A Current

Abstract In this study we have investigated the magnetic field associated with a current flowing in a circuit using Magnetic Force Microscopy (MFM). The technique is able to identify the magnetic field associated with a current flow and has potential for failure analysis.

scholarly journals Peristaltic Flow of a Magneto-Micropolar Fluid: Effect of Induced Magnetic Field

2008 ◽  
Vol 2008 ◽  
pp. 1-23 ◽  
Author(s):  
Kh. S. Mekheimer
Keyword(s):  
Magnetic Field ◽  
Current Distribution ◽  
Micropolar Fluid ◽  
Magnetic Force ◽  
Flow Analysis ◽  
Pressure Rise ◽  
Shear Stresses ◽  
Induced Magnetic Field ◽  
Symmetric Channel ◽  
Axial Pressure Gradient

We carry out the effect of the induced magnetic field on peristaltic transport of an incompressible conducting micropolar fluid in a symmetric channel. The flow analysis has been developed for low Reynolds number and long wavelength approximation. Exact solutions have been established for the axial velocity, microrotation component, stream function, magnetic-force function, axial-induced magnetic field, and current distribution across the channel. Expressions for the shear stresses are also obtained. The effects of pertinent parameters on the pressure rise per wavelength are investigated by means of numerical integrations, also we study the effect of these parameters on the axial pressure gradient, axial-induced magnetic field, as well as current distribution across the channel and the nonsymmetric shear stresses. The phenomena of trapping and magnetic-force lines are further discussed.

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