Outputs (33)

Characterisation of multiple conducting permeable objects in metal detection by polarizability tensors (2018)
Journal Article
Ledger, P. D., Lionheart, W. R. B., & Amad, A. A. S. (2019). Characterisation of multiple conducting permeable objects in metal detection by polarizability tensors. Mathematical Methods in the Applied Sciences, 42(3), 830-860. https://doi.org/10.1002/mma.5387

Realistic applications in metal detection involve multiple inhomogeneous-conducting permeable objects, and the aim of this paper is to characterise such objects by polarizability tensors. We show that, for the eddy current model, the leading order te... Read More about Characterisation of multiple conducting permeable objects in metal detection by polarizability tensors.

Transient solutions to nonlinear acousto-magneto-mechanical coupling for axisymmetric MRI scanner design: Transient nonlinear acousto-magneto-mechanical coupling in MRI (2018)
Journal Article
Bagwell, S., Ledger, P., Gil, A., & Mallett, M. (2018). Transient solutions to nonlinear acousto-magneto-mechanical coupling for axisymmetric MRI scanner design: Transient nonlinear acousto-magneto-mechanical coupling in MRI. International Journal for Numerical Methods in Engineering, 115(2), 209-237. https://doi.org/10.1002/nme.5802

In this work, we simulate the coupled physics describing a magnetic resonance imaging (MRI) scanner by using a higher-order finite element discretisation and a Newton-Raphson algorithm. To apply the latter, a linearisation of the nonlinear system of... Read More about Transient solutions to nonlinear acousto-magneto-mechanical coupling for axisymmetric MRI scanner design: Transient nonlinear acousto-magneto-mechanical coupling in MRI.

An Explicit Formula for the Magnetic Polarizability Tensor for Object Characterization (2018)
Journal Article
Ledger, P. D., & Lionheart, W. R. B. (2018). An Explicit Formula for the Magnetic Polarizability Tensor for Object Characterization. IEEE Transactions on Geoscience and Remote Sensing, 56(6), 3520-3533. https://doi.org/10.1109/tgrs.2018.2801359

The magnetic polarizability tensor (MPT) has attracted considerable interest due to the possibility it offers for characterizing conducting objects and assisting with the identification and location of hidden targets in metal detection. An explicit f... Read More about An Explicit Formula for the Magnetic Polarizability Tensor for Object Characterization.

A linearisedhp-finite element framework for acousto-magneto-mechanical coupling in axisymmetric MRI scanners: ACOUSTO-MAGNETO-MECHANICAL COUPLING IN MRI SCANNERS (2017)
Journal Article
Bagwell, S., Ledger, P. D., Gil, A. J., Mallett, M., & Kruip, M. (2017). A linearisedhp-finite element framework for acousto-magneto-mechanical coupling in axisymmetric MRI scanners: ACOUSTO-MAGNETO-MECHANICAL COUPLING IN MRI SCANNERS. International Journal for Numerical Methods in Engineering, 112(10), 1323-1352. https://doi.org/10.1002/nme.5559

We propose a new computational framework for the treatment of acousto-magneto-mechanical coupling that arises in low-frequency electro-magneto-mechanical systems such as magnetic resonance imaging scanners. Our transient Newton–Raphson strategy invol... Read More about A linearisedhp-finite element framework for acousto-magneto-mechanical coupling in axisymmetric MRI scanners: ACOUSTO-MAGNETO-MECHANICAL COUPLING IN MRI SCANNERS.

Resolving the sign conflict problem for hp–hexahedral Nédélec elements with application to eddy current problems (2017)
Journal Article
Kynch, R., & Ledger, P. (2017). Resolving the sign conflict problem for hp–hexahedral Nédélec elements with application to eddy current problems. Computers and Structures, 181, 41-54. https://doi.org/10.1016/j.compstruc.2016.05.021

A procedure for addressing the sign conflict issue for conforming hexahedral meshes.An efficient implementation of hierarchic hp-Nedelec elements in deal.II.Solution of a series of challenging 3D eddy current benchmark problems.Description of the ext... Read More about Resolving the sign conflict problem for hp–hexahedral Nédélec elements with application to eddy current problems.

Magnetic polarizability tensors for low frequency object classification and detection (2017)
Presentation / Conference Contribution
Ledger, P. D., & Lionheart, W. R. B. (2017, March). Magnetic polarizability tensors for low frequency object classification and detection. Paper presented at 2017 International Applied Computational Electromagnetics Society Symposium - Italy (ACES), Florence

There is considerable interest in obtaining a low-cost mathematical description, which describes the interaction between a low frequency alternating magnetic field and a conducting object. Electrical engineers have proposed that the voltage perturbat... Read More about Magnetic polarizability tensors for low frequency object classification and detection.

hp-Finite element solution of coupled stationary magnetohydrodynamics problems including magnetostrictive effects (2016)
Journal Article
Jin, D., Ledger, P., & Gil, A. (2016). hp-Finite element solution of coupled stationary magnetohydrodynamics problems including magnetostrictive effects. Computers and Structures, 164, 161-180. https://doi.org/10.1016/j.compstruc.2015.11.008

The first computational treatment of magnetostritive effects in conducting fluids.Consistent linearisation of the coupled non-linear equations.Computational solution using Newton-Raphson and hp-finite elements.Benchmarking against problems with homog... Read More about hp-Finite element solution of coupled stationary magnetohydrodynamics problems including magnetostrictive effects.

Understanding the magnetic polarizability tensor (2015)
Journal Article
Ledger, P. D., & Lionheart, W. R. B. (2016). Understanding the magnetic polarizability tensor. IEEE Transactions on Magnetics, 52(5), 1-16. https://doi.org/10.1109/tmag.2015.2507169

The aim of this paper is to provide new insights into the properties of the rank 2 polarizability tensor M̆ proposed by Ledger and Lionheart for describing the perturbation in the magnetic field caused by the presence of a conducting object in the ed... Read More about Understanding the magnetic polarizability tensor.

Characterizing the shape and material properties of hidden targets from magnetic induction data (2015)
Journal Article
Ledger, P. D., & Lionheart, W. R. B. (in press). Characterizing the shape and material properties of hidden targets from magnetic induction data. IMA Journal of Applied Mathematics, hxv015. https://doi.org/10.1093/imamat/hxv015

The aim of this paper is to show that, for the eddy current model, the leading order term for the perturbation in the magnetic field, due to the presence of a small conducting magnetic inclusion, can be expressed in terms of a symmetric rank 2 polari... Read More about Characterizing the shape and material properties of hidden targets from magnetic induction data.

A computational framework for the analysis of linear piezoelectric beams using hp-FEM (2015)
Journal Article
Poya, R., Gil, A. J., & Ledger, P. D. (2015). A computational framework for the analysis of linear piezoelectric beams using hp-FEM. Computers and Structures, 152, 155-172. https://doi.org/10.1016/j.compstruc.2015.01.012

A new computational framework for 3D linear piezoelectric beams using hp-FEM.Framework suitable for statics, dynamics, actuation and energy harvesting problems.Framework suitable for any anisotropy or electric polarisation orientation.New set of beam... Read More about A computational framework for the analysis of linear piezoelectric beams using hp-FEM.