A multi-sphere particle numerical model for non-invasive investigations of neuronal human brain activity

In this paper, a multi-sphere particle method is built-up in order to estimate the solution of the Poisson's equation with Neumann boundary conditions describing the neuronal human brain activity. The partial differential equations governing the relationships between neural current sources and the data produced by neuroimaging technique, are able to compute the scalp potential and magnetic field distributions generated by the neural activity. A numerical approach is proposed with current dipoles as current sources and going on in the computation by avoiding the mesh construction. The current dipoles are into an homogeneous spherical domain modeling the head and the computational approach is extended to multilayered con¯guration with different conductivities. A good agreement of the numerical results is shown and, for the first time compared with the analytical ones

An advanced variant of an interpolatory graphical display algorithm

In this paper an advanced interpolatory graphical display algorithm based on cardinal B-spline functions is provided. It is well-known that B-spline functions are a flexible tool to design various scale rapresentations of a signal. The proposed method allows to display without recursion a function at any desiderable resolution so that only initial data and opportune vectors weight are involved. In this way the structure of the algorithm is independent across the scale and a computational efficiency is reached. In this paper mono and bi-dimensional vectors weight generated by means of centered cubic cardinal B-spline functions have been supplied

IL METODO DELLE SOLUZIONI FONDAMENTALI PER LA SOLUZIONE DEL PROBLEMA DIRETTO M/EEG

The research already started on the mesh-free solution of the M / EEG direct problem has led to the development of a solver based on the method of fundamental solutions (MFS, method of fundamental solutions) able to manage the physical-geometric complexity of realistic models of the head more efficiently than traditional

The Interaction between Electric Field and Partial Discharges Simultaneously Detected in a HVDC cable under operating conditions

The reliability assessment of HVDC systems greatly depends on the insulating materials aging level and, among these, the cable insulation layer plays a fundamental role. With this in mind, in this work, the correlation between the electric field distribution and the triggering and evolution of PD in a DC cable containing an internal air void defect and subjected to normal operating conditions has been investigated. The aim is to demonstrate that the PD activity under DC depends on the electric field distribution which, in turn, is related to the conductivity gradient that varies with load. In a previous paper, the field distribution in a cable specimen was simulated. Here, instead, the field profiles have been experimentally obtained starting from the measured space charges detected simultaneously with the PD activity. For the charge detection and for the PD monitoring, an innovative PEA cell and a PD acquisition system have been used, respectively. Measurement results highlight that the PD behavior depends on both the electric field distribution and the time constant tau. Specifically, during the first 10 minutes of the beginning of the test, the field in the outer cable radius passes from 12 to 17 kV/mm and it is maintained around this last value until 30 minutes. PD are triggered after 1 minutes from the start of the test, corresponding to a PDIEF of 12.6 kV/mm calculated in the healthy cable section. The detected PD activity shows a PDRR with maximum value equal to 110 pulse/min at the beginning of the test. Whereas, after 15 minutes, the electric field variation dE/dt is approximately zero and the PDRR, that is maintained only by dE/dt results around 10 pulse/minute

A Meshfree Solver for the MEG Forward Problem

Noninvasive 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 (MFS) 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 (MPS), by numerically solving a boundary value problem for the electric scalar potential, derived from the quasi-stationary approximation of Maxwell’s 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