Salvatore Ganci

Physiological compatibility of wireless chargers for electric bicycles

The Inductive Power Transfer represents a viable solution of wireless battery charging for all users of electric mobility. This method brings some benefits to the electric vehicles, being a convenient technique, compared to the conventional wire-based battery charging. Among the electric vehicles, the electric bicycles particularly fit with this innovative method of battery charging. Nevertheless, the physiological effects of the produced magnetic fields need to be taken into account. In this paper, the design of an Inductive Power Transfer system for E-bike wireless battery charging is presented and the measurements concerning the surrounding magnetic field are provided in order to validate the model and evaluate the physiological compatibility of the system.

A Meshfree Solver for the MEG Forward Problem

Non-invasive estimation of brain activity via magnetoencephalography (MEG) involves an inverse problem whose solution requires an accurate and fast forward solver. To this end, we propose the method of fundamental solutions as a meshfree alternative to the boundary element method (BEM). The solution of the MEG forward problem is obtained, via the method of particular solutions, by numerically solving a boundary value problem for the electric scalar potential, derived from the quasi-stationary approximation of Maxwells equations. The magnetic field is then computed by the Biot-Savart law. Numerical experiments have been carried out in a realistic single-shell head geometry. The proposed solver is compared with a state-of-the-art BEM solver. A good agreement and a reduced computational load show the attractiveness of the meshfree approach.

The method of fundamental solutions in solving coupled boundary value problems for M/EEG

The estimation of neuronal activity in the human brain from electroencephalography (EEG) and magnetoencephalography (MEG) signals is a typical inverse problem whose solution process requires an accurate and fast forward solver. In this paper the method of fundamental solutions is, for the first time, proposed as a meshfree, boundary-type, and easy-to-implement alternative to the boundary element method (BEM) for solving the M/EEG forward problem. The solution of the forward problem is obtained by numerically solving a set of coupled boundary value problems for the three-dimensional Laplace equation. Numerical accuracy, convergence, and computational load are investigated. The proposed method is shown to be a competitive alternative to the state-of-the-art BEM for M/EEG forward solving.

Unconditionally stable meshless integration of time-domain Maxwell's curl equations

Grid based methods coupled with an explicit approach for the evolution in time are traditionally adopted in solving PDEs in computational electromagnetics. The discretization in space with a grid covering the problem domain and a stability step size restriction, must be accepted. Evidence is given that efforts need for overcoming these heavy constraints. The connectivity laws among the points scattered in the problem domain can be avoided by using meshless methods. Among these, the smoothed particle electromagnetics, gives an interesting answer to the problem, overcoming the limit of the grid generation. In the original formulation an explicit integration scheme is used providing, spatial and time discretization strictly interleaved and mutually conditioned. In this paper a formulation of the alternating direction implicit scheme is proposed into the meshless framework. The developed formulation preserves the leapfrog marching on in time of the explicit integration scheme. Studies on the systems matrices arising at each temporal step, are reported referring to the meshless discretization. The new method, not constrained by a grid in space and unconditionally stable in time, is validated by numerical simulations.

An augmented MFS approach for brain activity reconstruction

Weak electrical currents in the brain flow as a consequence of acquisition, processing and transmission of information by neurons, giving rise to electric and magnetic fields, which can be modeled by the quasi-stationary approximation of Maxwell’s equations. Electroencephalography (EEG) and magnetoencephalography (MEG) techniques allow for reconstructing the cerebral electrical currents and thus investigating the neuronal activity in the human brain in a non-invasive way. This is a typical electromagnetic inverse problem which can be addressed in two stages. In the first one a physical and geometrical representation of the head is used to find the relation between a given source model and the electromagnetic fields generated by the sources. Then the inverse problem is solved: the sources of measured electric scalar potentials or magnetic fields are estimated by using the forward solution. Thus, an accurate and efficient solution of the forward problem is an essential prerequisite for the solution of the inverse one. The authors have proposed the method of fundamental solutions (MFS) as an accurate, efficient, meshfree, boundary-type and easy-to-implement alternative to traditional mesh-based methods, such as the boundary element method and the finite element method, for computing the solution of the M/EEG forward problem. In this paper, further investigations about the accuracy of the MFS approximation are reported. In particular, the open question of how to efficiently design a good solution basis is approached with an algorithm inspired by the Leave-One-Out Cross Validation (LOOCV) strategy. Numerical results are presented with the aim of validating the augmented MFS with the state-of-the-art BEM approach. Promising results have been obtained.

Review of acoustic methods for space charge measurement

In the last decade, due to the increased use of direct current, the space charge accumulation phenomenon has reached more interest. In this regard, several non-destructive measurement systems were used. In particular, for solid dielectrics, the acoustic methods have had greater success. This review presents a brief historical evolution of the Pulse Electro-Acoustic (PEA) method, describing the working operation, the thicknesses analyzed and the spatial resolution for the different configurations of the PEA cell. The Pressure Wave Propagation (PWP) method in both configurations Piezo-PWP and Laser Induced Pressure Pulse (LIPP) is also described.

A numerical method for imaging of biological microstructures by VHF waves

Imaging techniques give a fundamental support to medical diagnostics during the pathology discovery as well as for the characterization of bio-medical structures. The imaging methods involve electromagnetic waves in a frequency range that spans from some Hz to GHz and over. Most of these methods involve ionizing waves and scanning of a large human body area even if only a focused inspection is needed. In this paper, a numerical method to evaluate the shape of microstructures for application in the medical field, with a very low invasiveness for the human body, is proposed. In particular, the tooths root canal is considered. In fact, this is one of the hot topics in the endodontic procedures where rotary instruments are widely used. These instruments are subjected to sudden mechanical damage during the surgical process, due to cyclic fatigue directly related to the canals geometrical characteristics. In order to develop an improved endodontic procedure so that instrument breakage probability and canal milling precision are optimized, preliminary canal root reconstruction techniques have to be implemented. These techniques are usually based on invasive X-ray imaging. Thus, a minimally invasive, easy to use imaging technique that can be applied many times on the patient is of great interest. To this aim, a method based on a flexible thin-wire antenna radiating non ionizing VHF waves is proposed. By measuring the spatial magnetic field distribution in the neighboring area, it is possible to reconstruct the microstructure image by estimating the shape of the antenna against a sensor panel. The mathematical model is strictly non-linear and the inverse problem described above is solved numerically; first simulation results are presented in order to show the validity and the robustness of the proposed approach.

Attenuation of low frequency magnetic fields produced by HV underground power cables

High-voltage underground cable systems are becoming more common as the demand for electrical power within urban centers increase, also considering the difficulties in building new overhead power lines in the vicinity of city centers because of authorization issues. Therefore, interest towards the evaluation of magnetic fields produced by high-voltage power lines has been triggered during the last decade and concern about effects on human health of exposure to extra low frequency (ELF) magnetic fields due to power lines has been increasing as well. Hence, the evaluation of the magnetic field produced by underground power cables is important in order to develop methods for mitigating their influence on the surrounding environment. In this paper, after a description of some technical solutions adopted nowadays to reduce ELF magnetic fields generated by power cables, a case study on a 380 kV power line will be considered.

A novel numerical meshless approach for electric potential estimation in transcranial stimulation

In this paper, a first application of the method of fundamental solutions in estimating the electric potential and the spatial current density distribution in the brain due to transcranial stimulation, is presented. The coupled boundary value p roblems for the electric potential are solved in a meshless way, so avoiding the use of grid based numerical methods. A multi-spherical geometry is considered and numerical results are discussed.

Mitigation of 50 Hz magnetic field produced by an overhead transmission line

Power transmission utilities are challenged by the need to expand transmission system capacity to meet growing energy demands. The impact of high voltage overhead transmission lines on the environment represents a hot topic in the context of transport and distribution of electrical energy. In particular, interest towards the effects of extra low frequency (ELF) magnetic fields generated by high-voltage power transmission lines has been increasing significantly during the last decade, giving rise to a number of policy initiatives and research activities. Therefore, the evaluation of the magnetic field generated by conductors of overhead lines is of primary importance in order to develop methods for mitigating the influence of overhead lines on the surrounding environment. In this paper, some technical solutions that are used nowadays to reduce 50 Hz magnetic fields generated by power lines are analyzed; simulation results concerning a case study on an actual 150 kV Italian power transmission line are also presented.