This paper describes a fuzzy quality-controller for video coding systems based on the H.261 recommendation. The picture quality is tuned by a classification of the blocks of each frame of the sequence based on a simplified model of the human visual system. The quantization parameter is evaluated according to this classification making more relevant parts be coded with finer details at the expense of less significant regions. The system is based on a restricted number of fuzzy rules and can be easily reconfigured if a different classification criterion must be adopted. The subjective quality of coded sequences is better than the one obtained by the reference model at the cost of higher computational tasks.

A low-power architecture for 2D-DCT is presented. It has been designed for portable H.261-compliant video-telephone applications, but most of the results and considerations apply to MPEG systems too. The presence of quantization in the coding process has been exploited, adapting the precision of DCT calculations to the quantization noise level. The proposed architecture has the capability of dynamically controlling power consumption by reducing the precision to the minimum required level and turning off sub-systems when they are not necessary for the computation. Compared with a standard implementation, power consumption is reduced by a factor between 7 and 10, without appreciable degradation of the transmission quality.

The problems related to the hydrodynamic simulation of semiconductor devices operating at liquid nitrogen temperature are investigated, with emphasis on the numerical aspects. A discretization strategy is proposed that allows one to incorporate in a conventional hydrodynamic program typical low-temperature effects, such as Fermi statistics and incomplete ionization, as well as proper boundary conditions. The suggested technique has been implemented in the hydrodynamic version of the program HFIELDS, and it has been tested by means of the simulation of a submicron n-channel MOSFET.>