Analytical model for the magnetic field and force in a magnetophoretic microsystem

2006 ◽  
Vol 39 (9) ◽  
pp. 1724-1732 ◽  
Author(s):  
E P Furlani ◽  
Y Sahoo
Keyword(s):  
Magnetic Field ◽  
Analytical Model ◽  
The Magnetic Field

scholarly journals Normalization of double-circuit overhead line magnetic field inside Khrushchev building

2021 ◽  
pp. 38-41
Author(s):  
K. V. Chunikhin ◽  
V. S. Grinchenko
Keyword(s):  
Magnetic Field ◽  
Numerical Simulation ◽  
Analytical Model ◽  
Reference Level ◽  
Overhead Line ◽  
Field Normalization ◽  
Living Space ◽  
The Magnetic Field

This paper deals with the mitigation of 110 kV double-circuit overhead line magnetic field inside five-story Khrushchev buildings. We show that the magnetic field can exceed the reference level 0.5 μT in 90 % part of living space. To mitigate the magnetic field, we propose the inverted L-shaped grid shield with conductors on the wall and in the attic of the building. Using the analytical model of the grid shield and the numerical simulation, we determine the parameters of the L-shaped grid shield which provides the magnetic field normalization in 97 % part of living space. Further improvement of the grid shield profile, in particular, the placement of some conductors in the basement, allows to reduce the quantity of metal of the shield by 15 % while maintaining the shielding efficiency. Also we consider the magnetic field normalization for the overhead line with a rated current of 500 A. In this case, the quantity of metal of the grid shield increases 2.74 times.

Electromagnetic Nondestructive Testing Model and Surface Magnetic Field Analysis for Circumferential Cracks on Metal Rod

2019 ◽  
Vol 2 (4) ◽  
Author(s):  
Feng Jiang ◽  
Shulin Liu ◽  
Shaojie Xin ◽  
Hongli Zhang
Keyword(s):  
Magnetic Field ◽  
Analytical Model ◽  
Magnetic Induction ◽  
Crack Depth ◽  
Field Analysis ◽  
Surface Magnetic Field ◽  
Circumferential Crack ◽  
Inner Surface ◽  
Magnetic Induction Intensity ◽  
The Magnetic Field

Abstract In this paper, an analytical model for a metal rod with a coating layer is proposed to evaluate circumferential crack from the signals of the surface magnetic field. In the proposed model, magnetic vector equations for four regions of space were built, and series expressions of the magnetic field were proposed by the truncated region eigenfunction method. The calculation results can show the three-dimensional distribution of axial and radial magnetic induction intensities on the surface of a metal rod clearly. In addition, the analytical model is verified by using comsol finite element simulation, which also demonstrates that induced eddy currents on the inner surface of the metal rod with cracks appear to be propelled toward the inner layer of the metal rod and the presence of a circumferential crack directly causes a decrease in the induced eddy current on the inner surface of the rod. The results calculated from the analytical model indicated that the model is capable of providing an accurate variation in the magnetic field due to circumferential cracks at different depths. The analytical results showed that the radial magnetic induction intensity increases by 0.16 × 10−3 T, while the axial magnetic induction intensity decreases by 0.3 × 10−3 T as the crack depth increases from 0 to 3 mm.

scholarly journals Analytical Model for the Magnetic Field Distribution in a Flux Modulation Superconducting Machine

2019 ◽  
Vol 55 (12) ◽  
pp. 1-9 ◽  
Author(s):  
Alexandre Colle ◽  
Thierry Lubin ◽  
Sabrina Ayat ◽  
Olivier Gosselin ◽  
Jean Leveque
Keyword(s):  
Magnetic Field ◽  
Analytical Model ◽  
Field Distribution ◽  
Magnetic Field Distribution ◽  
Flux Modulation ◽  
The Magnetic Field

Design and Analysis of a New Type of Electromagnetic Damper With Increased Energy Density

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Lei Zuo ◽  
Xiaoming Chen ◽  
Samir Nayfeh
Keyword(s):  
Magnetic Field ◽  
Analytical Model ◽  
Eddy Current ◽  
High Efficiency ◽  
High Reliability ◽  
Damping Force ◽  
Element Analysis ◽  
Eddy Current Damper ◽  
New Type ◽  
The Magnetic Field

Eddy current dampers, or electromagnetic dampers, have advantages of no mechanical contact, high reliability, and stability, but require a relatively large volume and mass to attain a given amount of damping. In this paper, we present the design and analysis of a new type of eddy current damper with remarkably high efficiency and compactness. Instead of orienting the magnetic field in a uniform direction, we split the magnetic field into multiple ones with alternating directions so as to reduce the electrical resistance of the eddy current loops and increase the damping force and damping coefficient. In this paper, an analytical model based on the electromagnetic theory for this type of eddy current damper is proposed, and a finite-element analysis (FEA) is carried out to predict the magnetic field and current density. Experimental results agree well with the analytical model and FEA predictions. We demonstrate that the proposed eddy current damper achieves a damping density (N s/m m3) and a dimensionless damping constant as much as 3–5 times as those in the literature. The dependence of damping on velocity and frequency is also examined.

Conduit Flow Control Through Magnetorheology

2011 ◽  
Author(s):  
Mario F. Letelier ◽  
Juan S. Stockle ◽  
Dennis A. Siginer
Keyword(s):  
Magnetic Field ◽  
Pressure Gradient ◽  
Flow Control ◽  
Analytical Model ◽  
Working Conditions ◽  
Constant Pressure ◽  
Working Fluid ◽  
Instantaneous Rate ◽  
Flow Fluctuations ◽  
The Magnetic Field

In this paper it is addressed the problem of flow stability in conduits when an essentially steady flow is perturbed by undesirable fluctuations of the pressure gradient. This problem may arise when working conditions in conduit systems induce sporadic or permanent oscillations of the pressure at the end of some conduits. In cases where the flow occurs in closed circuits and it is important to reduce or eliminate flow fluctuations, it is possible to impose flow control by making use of the magnetorheological properties of some fluids. An analytical model is presented in which the working fluid is assumed to be affected by a magnetic field whose strength is proportional to the instantaneous rate of flow. In this way, it is shown that oscillatory perturbations of an otherwise constant pressure gradient can be damped away through the synchronized oscillations of the yield stress generated in the fluid by the magnetic field. The paper includes the solution of the analytical model and several examples of applications.

Steady flows in the core of precessing planets : effects of the geometry and an applied magnetic field.

2020 ◽  
Author(s):  
Raphael Laguerre ◽  
Aymeric Houliez ◽  
David Cébron ◽  
Véronique Dehant
Keyword(s):  
Magnetic Field ◽  
Analytical Model ◽  
Inner Core ◽  
Rotation Axis ◽  
The Body ◽  
External Boundary ◽  
Core Size ◽  
Major Purpose ◽  
Resonance Amplitude ◽  
The Magnetic Field

<p>The Earth is submitted to the gravitational effect of different objects,  resulting  in  small  variations  of  the  orientation  of  its  axis  rotation.   The  precession corresponds to the rotation of the body spin axis around the normal to the elliptic plane. The primary flow forced by precession in a sphere is mainly a tilted solid body rotation, a flow of uniform vorticity. In this study we focused on the pseudo-resonance between the precessional forcing  and  the  spin-over  mode,  detected  as  a  peak  of  amplitude  of  the  norm  of the  vorticity  of  the  fluid.   We  show  the  influences  of  both  the  geometry and the application of an uniform external magnetic field on the external boundary, onto this pseudo-resonance.  The major purpose is to validate a semi-analytical model to allow its interpolation to planetary bodies.  We compared the semi-analytical model [Noir and C ́ebron, 2013] with numerical simulations performed with XSHELLS [Schaeffer, 2013],  which give us the components of the fluid vorticity in a precessing frame. We compared also the spin-over mode coefficients, used to simulate the viscous  effect  on  the  model,  with  two  methods :  an  empirical  equation  and  the numerical solver Tintin [Triana et al., 2019], taking into account the solid inner-core size (η=RI/R).  The differential rotation between the flow and the container, obtained with the model and the XSHELLS simulations, show us a verygood agreement especially for a small Ekman number (E= 10^−5), thus the spin-over mode coefficients for small E and η≤0.5.  An increase of the inner-core size  implies  a  decrease  of  the  resonance  amplitude  caused  by  the  supplementary Ekman layer added at the Inner Core Boundary (ICB); nevertheless thecolatitude (αf) and the longitude (φf) of the fluid don’t change significantly.The  application  of  a  uniform  magnetic  field  at  the  CMB  implies  a  decrease of the resonance amplitude, but also a modification of the mean rotation axis direction.  Indeed, the coupling between the viscous flow and the magnetic field induces a modification of the αfand φf, which follow the main direction angle of the magnetic field axis.  We observe small discrepancies between the simulations (XSHELLS and Tintin) and the model but the behavior following different parameters (Po,α angle,Ro,η,β angle, Λ) is well understood.  As a result, we applied the models at few parameter ”realistic values” of planetary objects like terrestrial planets but also ice’s satellites.</p><p>References</p><p>[Noir and C ́ebron, 2013]  Noir,  J.  and  C ́ebron,  D.  (2013).    Precession-driven flows in non-axisymmetric ellipsoids.Journal of Fluid Mechanics, 737:412–439.</p><p>[Schaeffer, 2013]  Schaeffer, N. (2013).  Efficient spherical harmonic transforms aimed  at pseudospectral numerical  simulations.Geochemistry, Geophysics,Geosystems, 14(3):751–758.</p><p>[Triana et al., 2019]  Triana, S. A., Rekier, J., Trinh, A., and Dehant, V. (2019).The coupling between inertial and rotational eigenmodes in planets with liq-uid cores.Geophysical Journal International.</p>

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