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In this paper a method is presented for an efficient solution of the direct problem (find the scattered field for a given thin crack and driving field) in the time domain. This is a fundamental step in any non destructive evaluation problem. Two different approaches, one in the time domain and the other based on Fourier analysis, are used and compared with reference to a configuration for which some experimental results are available. The advantages and drawbacks of the two approaches are briefly discussed.

In this paper we present a fast method for the computation of matrix‐by‐vector products arising from the discretization of an integral formulation of the three‐dimensional eddy current problem. The approach is based on the distinction between short and long range interactions. The features of the method will be discussed with reference to some numerical examples, also in view of an extension to the nonlinear case of superconductors.

To investigate the possible application of carbon nanotubes (CNTs) as interconnects and antennas.

An electromagnetic macroscopic modelling of CNT is derived. The conduction electrons of the nanotube are considered as a 2D fluid moving on the surface representing the positive ion lattice. The linearized Euler's equation describing the fluid motion is used as a macroscopic constitutive relationship to be coupled to Maxwell's equation. A surface integral formulation coupled to the fluid model is solved numerically using a finite element method. For peculiar configurations, transmission line‐like parameters of CNTs are derived.

Single wall CNT interconnects, due to the high resistance and characteristic impedance with respect to ideally scaled silicon technology, should be used in arrays and bundles.

Only single wall CNTs are considered.

The paper present a novel approach to CNTs and provides a comparison among the behaviour of CNTs with respect to ideally‐scaled silicon technology.

To apply two different integral formulations of full‐Maxwell's equations to the numerical study of interconnects in a low‐frequency range and compare the results.

The first approach consists of a surface formulation of the full‐Maxwell's equations in terms of potentials, giving rise to a surface electric field integral equation. The equation, given in a weak form, is solved by using a finite element technique. The solenoidal and non‐solenoidal components of the electric current density are separated using the null‐pinv decomposition to avoid the low‐frequency breakdown. The second model is an extension of partial element equivalent circuit technique to unstructured meshes allowing the use of triangular meshes. Two systems of meshes tied by duality relations are defined on multiconductor systems. The key point in the definition of the equivalent network is to associate the pair primal edge/dual face to a circuit branch. Solution of the resulting electrical network is performed by a modified nodal analysis method and regularization of the outcoming matrix is accomplished by standard techniques based on the addition of suitable resistors.

Both the formulation have a regular behaviour at very low frequency. This is automatically achieved in the first approach by using the null‐pinv decomposition.

Surface sources of fields.

Two different integral formulations of full‐Maxwell's equations for the numerical study of interconnects are compared in terms of low‐frequency behaviour.

The purpose of the study is to design the compensation network of a dynamic wireless power transfer system, considering the movement of the receiving coil along an electrified track with a large number of inductors buried on the road.

A finite element model has been developed to calculate the self-inductances of transmitting and receiving coils as well as the mutual inductances between the receiving coil and the transmitting ones in the nearby and for various relative positions. The calculated lumped parameters, self-inductances and mutual inductances depending on the relative positions between the coils, have been considered to design the compensation network of the active coils, which is composed of three capacitive or inductive reactances connected in the T form. The optimal values of the six reactances, three for the transmitting coils and three for the receiving one, have been calculated by resorting to the Genetic Algorithm NSGA-II.

In this paper, the results obtained by means of the optimizations have broadly discussed. The optimal values of the reactances of the compensation networks show a clear trend in the receiving part of the circuit. On the other hand, the problem seems very sensitive to the values of the reactances in the transmitting circuit.

Dynamic wireless power transfer system is one of the newest ways of recharging electric vehicles. Hence, the design of compensation networks for this kind of systems is a new topic, and there is the need to investigate possible solutions to obtain a good performance of the recharging system.

To provide a validation of a three‐dimensional (3D) macroscopic model for superconductors comparing numerical to experimental AC losses of a BSCCO‐2223 tape subject to an orthogonal magnetic field and a transport current.

We solve in 3D geometries the eddy current problem in presence of superconductors, represented by a power‐law characteristic rewritten into a variational form. An integral formulation of the magneto‐quasistatic Maxwell's equations is used. The solution of the problem is found by an unconstrained minimization of a suitable functional. The numerical results on AC losses computation are compared to experimental data.

The agreement between numerical and experimental data is good in a wide range of currents and magnetic fields.

The magnetic field is assumed to be orthogonal to the tape. Different incidence angles should be taken into account.

It is possible to extend the range of validity of the engineering formulae for AC losses used in the work.

The paper provides a validation of a numerical code against experimental results: this is always challenging in the field of applied superconductivity.

Nowadays, nano-antennas or nanoscale absorbers made by innovative materials such as carbon nanotubes are gaining more and more interest, because of their outstanding features. The purpose of this paper is to investigate the scattering properties of carbon nanotubes, either isolated or arranged in arrays. The peculiar behaviour of such innovative materials is studied, taking also into account the finite length of the structure and the dependence of the scattering field from the operating temperature.

First a model is presented for the electrical transport along the carbon nanotubes, based on Boltzmann quasi-classical transport theory. The model includes quantistic and inertial phenomena observed in the carbon nanotube electrodynamics. The model also includes the effects of temperature. Using this electrodynamical model, the electromagnetic formulation of the scattering problem is cast in terms of a Pocklington-like equation. The numerical solution is obtained by means of the Galerkin method, with special care in handling the logarithmic singularity of the kernel. Case studies are carried out, either referred to isolated single-wall carbon nanotubes (SWCNTs) and array of SWCNTs.

The scattering properties of SWCNT are strongly influenced by the temperature and by the distance between the tubes. As temperature increases, the amplitude of the resonance peaks decreases, at a rate which is double the rate of changes of temperature. The resonance frequencies are insensitive to temperature. As for the distance between the tubes in an array, it influence the scattering resonance introducing a shift in the resonance frequencies which is appreciable for distances lower than the semi-length of the CNT. For higher distances the CNT scattered field may be regarded as the sum of the fields emitted by each CNT, as if they were isolated.

As far as now only SWCNTs have been studied. The multi-wall carbon nanotubes would show a richer behaviour with temperature, due to the joint effect of reduction of the mean free path and increase of the number of conducting channels, as temperature increases.

Possible use of carbon nanotubes as absorbing material or scatterers.

The model presented here is based on a self-consistent and physically meaningful description of the CNT electrodynamics, which takes rigorously into account the effect of temperature, size and chirality of each CNT.

A new method for the numerical computation of the dynamic behaviour of electro‐dynamic loudspeakers is presented. The numerical scheme, based on the finite element method (FEM), allows the simulation of coupled magnetic, mechanical and acoustic fields. The obtained simulation results are in good agreement with measured data.

The paper aims to present an overview of techniques for the identification in the frequency domain of reduced order models for distributed passive electromagnetic structures.

Most known approaches proposed in different application contexts are described within a unified framework.

A passive reduced order model of an unshielded twisted pair is fully developed with the combination of vector fitting algorithm and the passivity enforcement via Hamiltonian perturbation.

A state‐of‐the‐art picture of the frequency domain identification and passivity enforcement techniques is given, and a test case of actual interest fully analysed.

In the ideal crack model (negligible thickness and an impenetrable barrier to electric current) in eddy‐current testing frame, the field‐flaw is equivalent to a current dipole layer on its surface. This dipole density is the solution of an integral equation with a hyperstrong kernel. This model has shown its efficiency, as well the computing accuracy, as for the CPU time. Furthermore, the case of a current leakage across crack was considered by introducing an equivalent conductivity of the crack. This paper aims at simulating a local varying conductivity. In particular, we focus on a constant piecewise conductivity. In this last case, because of the presence of the hypersingular kernel in the equation, the numerical scheme using the ideal case has to be modified.