of;
Electromechanical;
Engineering,;
University;
of;
Beira;
Interior,;
Calqada;
Fonte;
do;
Lameiro,;
Covilh6;
6201-001,;
Portugal;
of;
Electrical;
Engineering;
and;
Computer,;
Instituto;
Superior;
TOcnico,;
Av.;
Rovisco;
Pais,;
Lisbon;
1049-001,;
Portugal;