Margarida Almeida

Slip-casting of alumina bodies with differential porosities

Abstract Rheological and sedimentation studies were used to determine floc structure in aqueous alumina suspensions in which the degree of flocculation was varied by modifying the pH of the suspensions. A slip-casting technique was developed to allow fabrication of alumina bodies with differential porosities by varying the degree of flocculation of the suspensions during the forming period. The porosity and density of the pre-sintered bodies were determined. The results show that the conditions of the starting suspensions influence the density of the bodies and that their variation during the slip-casting process enable samples to be fabricated with differential porosity.

Thermal expansion of ceramics in the MgO-CaO system

The thermal expansion coefficients of refractory ceramics with different compositions in the MgO-CaO system have been measured, and compared with theoretical values for multiphase composites calculated on the basis of the equations of Turner and of Kerner. Good agreement with the predictions of the Turner equation has been found.

Automatic identification in accessible iTV services: proposal of an IPTV interface

Interactive Television (iTV) services that currently exist may be subject to a set of improvements in order to become more efficient and meet the needs of visually impaired users (VIU). The current television distribution infrastructures, since supplemented with a return channel and appropriated Set-Top Boxes (STB), open an interesting opportunity for the creation of an iTV service that integrates advanced features and can be automatically adjusted to the preferences of users with visual impairment. In this context, this paper proposes an adapted iTV service for visually impaired users complemented by an automatic user identification system. With this complementarity, the service can be dynamically adjusted to the preferences of the user that is in fact watching TV, automatically invoking the options previously selected in the respective settings.