References of "Specogna, Ruben"
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See detailA perturbation method for the T-Ω geometric eddy-current formulation
Codecasa, Lorenzo; Dular, Patrick ULg; Specogna, Ruben et al

in IEEE Transactions on Magnetics (2010), 46(8), 3045-3048

A perturbation method for the T-Ω geometric formulation to solve eddy-current problems is introduced. The proposed formulation is applied to the feasibility design of a nondestructive evaluation device ... [more ▼]

A perturbation method for the T-Ω geometric formulation to solve eddy-current problems is introduced. The proposed formulation is applied to the feasibility design of a nondestructive evaluation device suitable to detect “long” longitudinal flaws in hot steel bars. [less ▲]

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See detailTime-domain geometric eddy-current A formulation for hexahedral grids
Codecasa, Lorenzo; Dular, Patrick ULg; Specogna, Ruben et al

in IEEE Transactions on Magnetics (2010), 46(8), 3301-3304

The aim of this paper is to present a 3-D time-domain eddy-current A formulation based on the discrete geometric approach (DGA) over unstructured and nonorthogonal hexahedral dual grids. The resulting ... [more ▼]

The aim of this paper is to present a 3-D time-domain eddy-current A formulation based on the discrete geometric approach (DGA) over unstructured and nonorthogonal hexahedral dual grids. The resulting differential algebraic system of equation, solved by means of a singly-diagonally implicit Runge-Kutta (SDIRK) variable step-size solver, leads to very accurate results at reduced computational costs, as shown by numerical analysis. [less ▲]

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See detailA non-destructive testing application solved with A-X geometric eddy-current formulation
Codecasa, Lorenzo; Dular, Patrick ULg; Specogna, Ruben et al

in COMPEL (2010), 29(6), 1606-1615

Purpose – The purpose of this paper is to introduce a perturbation method for the A-X geometric formulation to solve eddy-current problems and apply it to the feasibility design of a non-destructive ... [more ▼]

Purpose – The purpose of this paper is to introduce a perturbation method for the A-X geometric formulation to solve eddy-current problems and apply it to the feasibility design of a non-destructive evaluation device suitable to detect long-longitudinal volumetric flaws in hot steel bars. Design/methodology/approach – The effect of the flaw is accurately and efficiently computed by solving an eddy-current problem over an hexahedral grid which gives directly the perturbation due to the flaw with respect to the unperturbed configuration. Findings – The perturbation method, reducing the cancelation error, produces accurate results also for small variations between the solutions obtained in the perturbed and unperturbed configurations. This is especially required when the tool is used as a forward solver for an inverse problem. The method yields also to a considerable speedup: the mesh used in the perturbed problem can in fact be reduced at a small fraction of the initial mesh, considering only a limited region surrounding the flaw in which the mesh can be refined. Moreover, the full three-dimensional unperturbed problem does not need to be solved, since the source term for computing the perturbation is evaluated by solving a two-dimensional flawless configuration having revolution symmetry. Originality/value – A perturbation method for the A-X geometric formulation to solve eddy-current problems has been introduced. The advantages of the perturbation method for non-destructive testing applications have been described. [less ▲]

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See detailConstitutive matrices using hexahedra in a discrete approach for eddy currents
Dular, Patrick ULg; Specogna, Ruben; Trevisan, Francesco

in IEEE Transactions on Magnetics (2008), 44(8), 694-697

We examine the construction of reluctivity and Ohm's constitutive matrices for discrete geometric approaches using nonregular hexahedra as primal volumes. The effect of element deformation on the ... [more ▼]

We examine the construction of reluctivity and Ohm's constitutive matrices for discrete geometric approaches using nonregular hexahedra as primal volumes. The effect of element deformation on the representation of uniform fields have been investigated for static fields. Then convergence and accuracy of the proposed matrices has been carried out using an eddy-current problem as working example. [less ▲]

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