Stochastic Uncertainty Quantification of the Conductivity in EEG Source Analysis by Using Polynomial Chaos Decomposition

in IEEE Transactions on Magnetics (2010), 46(8), 3457-3460

The electroencephalogram (EEG) is one of the techniques used for the non-invasive diagnosis of patients suffering from epilepsy. EEG source localization identifies the neural activity, starting from ... [more ▼]

The electroencephalogram (EEG) is one of the techniques used for the non-invasive diagnosis of patients suffering from epilepsy. EEG source localization identifies the neural activity, starting from measured EEG. This numerical localization procedure has a resolution, which is difficult to determine due to uncertainties in the EEG forward models. More specifically, the conductivities of the brain and the skull in the head models are not precisely known. In this paper, we propose the use of a non-intrusive stochastic method based on a polynomial chaos decomposition for quantifying the possible errors introduced by the uncertain conductivities of the head tissues. The accuracy and computational advantages of this non-intrusive method for EEG source analysis is illustrated. Further, the method is validated by means of Monte Carlo simulations. [less ▲]

Finite-Element Analysis of a Shielded Pulsed-Current Induction Heater-- Experimental Validation of a Time-Domain Thin-Shell Approach

in Proceedings of the 8th International Symposium on Electric and Magnetic Fields (EMF2009) (2009)

A time-domain extension of the classical frequency-domain thin-shell approach is used for the finite-element analysis of a shielded pulse-current induction heater. The time-domain interface conditions at ... [more ▼]

A time-domain extension of the classical frequency-domain thin-shell approach is used for the finite-element analysis of a shielded pulse-current induction heater. The time-domain interface conditions at the shell surface are expressed in terms of the average (zero-order) instantaneous flux and current density vectors in the shell, as well as in terms of a limited number of higher-order components. The three-dimensional thin-shell model is validated by comparing the numerical results with measurements performed on the heating device at different working frequencies. [less ▲]

Analysis of perforated magnetic shields for electric power applications

in Proceedings of the 13th Biennial IEEE Conference on Electromagnetic Field Computation (CEFC2008) (2008)

Inclusion of a stress-dependent Preisach model in 2D FE calculations

in Compel-the International Journal for Computation and Mathematics in Electrical and Electronic Engineering (2006), 25(1), 81-90

Purpose - Mechanical stress can heavily affect the magnetic behaviour law in ferromagnetic materials. This paper, aims to take into account the effect of mechanical stress into a hystreresis model. This ... [more ▼]

Purpose - Mechanical stress can heavily affect the magnetic behaviour law in ferromagnetic materials. This paper, aims to take into account the effect of mechanical stress into a hystreresis model. This model is implemented in a finite element analysis code and tested in the case of a simple system. Design/methodology/approach - A simple extension of the classical Preisach model is proposed, in which a function linked to the Preisach density is parameterized using the mechanical stress as a supplementary parameter. The methodology is based on experimental measurements for identifying the required function. As a first approach, a linear interpolation is used between the measurements in order to have a continuous evolution of the magneto-mechanical behaviour. This model has been tested in the case of a steel sheet in which width is not constant in order to obtain a non-uniform distribution of stress and magnetic flux density. Findings - The model can predict the magneto-mechanical behaviour with a good accuracy in the case of tensile stress. Implementation of the model in finite element analysis has shown that the model can predict the behaviour of steel sheet subject to a non-uniform stress distribution. Originality/value - This paper shows that a classical hysteresis model can be extended to take into account the magneto-mechanical behaviour. This is useful for the design of electrical machines which are subject to non-negligible mechanical stress. [less ▲]