A state space approach and formulation for the solution of nonlinear 3-D transient eddy current problems

Mohammed, Osama A.; Uler, F.G.

doi:10.1109/20.123878

Cited by 7 publications

(10 citation statements)

References 5 publications

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“…Here we used the state-space approach based on the magnetic vector potential and electric scalar potential ( A − ϕ ) method to derive the FEM solution (Mohammed & Üler 1992). Consider a whole volume V that consists of a conductive region V 2 and an insulating region V 1 , while the region V 2 is surrounded by the region V 1 .…”

Section: Methodsmentioning

confidence: 99%

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Solving the forward problem of magnetoacoustic tomography with magnetic induction by means of the finite element method

Zhu

et al. 2009

Phys. Med. Biol.

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Magnetoacoustic Tomography with Magnetic Induction (MAT-MI) is a recently proposed imaging modality to image the electrical impedance of biological tissue. It combines the good contrast of electrical impedance tomography with the high spatial resolution of sonography. In this paper, threedimensional MAT-MI forward problem was investigated using the finite element method (FEM). The corresponding FEM formulas describing the forward problem are introduced. In the finite element analysis, magnetic induction in an object with conductivity values close to biological tissues was first carried out. The stimulating magnetic field was simulated as that generated from a threedimensional coil. The corresponding acoustic source and field were then simulated. Computer simulation studies were conducted using both concentric and eccentric spherical conductivity models with different geometric specifications. In addition, the grid size for finite element analysis was evaluated for model calibration and evaluation of the corresponding acoustic field.

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Section: Methodsmentioning

confidence: 99%

“…Assuming J i 1 ( t ) is piecewise homogeneous and using the property of the state transfer matrix in (12), Eq. 11 becomes (Mohammed & Üler 1992)…”

Section: Methodsmentioning

confidence: 99%

Solving the forward problem of magnetoacoustic tomography with magnetic induction by means of the finite element method

Zhu

et al. 2009

Phys. Med. Biol.

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“…The finite element method (FEM) has proven to be an effective numerical technique for solving electromagnetic field problems, including modeling large-scale eddy current problems in electromagnetic engineering (12)(13)(14)(15)(16)(17). It has also been adopted to establish the eddy currents model of the PM MRI system with a static magnetic field of 0.12T for the 2D model with longitudinal coils (18)(19)(20) and a 3D model with transverse coils (21,22).…”

Section: Introductionmentioning

confidence: 99%

Characterization and reduction of X‐gradient induced eddy currents in a NdFeB magnetic resonance imaging magnet‐3D finite element method‐based numerical studies

Li¹,

Xia²,

F³

et al. 2011

Concepts Magn Reson

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ABSTRACT:In permanent magnetic resonance imaging (MRI) systems, pulsed gradient fields induce strong eddy currents in the conducting structures of the magnet. The gradient field for image encoding is perturbed by these eddy currents, thus leading to MR image distortions. The conventional approach for the reduction of the eddy current effects is to employ passive shielding (an eddy current board). However, the analysis of the passive shielding structure is typically nonoptimal. In this article, a comprehensive 3D finite element method (FEM) model for the characterization of eddy currents in the ferromagnetic materials of the magnet is developed, which is helpful for the evaluation of the shielding effects and the improvement of passive shielding designs. During the numerical analyses, the eddy current source was introduced through X-gradient coils, nonlinearity, and the anisotropy of the laminated silicon steel structure was considered, with the selection of a penalty factor in the FEM governing equations being also detailed. Based on the simulations results, suggestions have been made for passive shielding designs.

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“…Recently, this model has also been used for the study of characteristics of permanent magnet materials [23]. The FE method has proven to be an effective numerical technique to solve electromagnetic field problems, including model large-scale eddy current problems in electromagnetic engineering [24][25][26][27][28][29]. In this paper, the eddy currents in pole pieces are analyzed using the FE method combined with a scalar Preisach model.…”

Section: Introductionmentioning

confidence: 99%

Finite element analysis of gradient z-coil induced eddy currents in a permanent MRI magnet

Xia

Chen

et al. 2011

Journal of Magnetic Resonance

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A state space approach and formulation for the solution of nonlinear 3-D transient eddy current problems

Cited by 7 publications

References 5 publications

Solving the forward problem of magnetoacoustic tomography with magnetic induction by means of the finite element method

Solving the forward problem of magnetoacoustic tomography with magnetic induction by means of the finite element method

Characterization and reduction of X‐gradient induced eddy currents in a NdFeB magnetic resonance imaging magnet‐3D finite element method‐based numerical studies

Finite element analysis of gradient z-coil induced eddy currents in a permanent MRI magnet

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