In this paper, the classic Levy identification method is reviewed and reformulated using a complex representation. This new formulation addresses the well known bias of the classic method at low frequencies. The formulation is generic, coping with both integer order and fractional order transfer functions. A new algorithm based on a stacked matrix and its pseudoinverse is proposed to accommodate the data over a wide range of frequencies. Several simulation results are presented, together with a real system identification. This system is the Archimedes Wave Swing, a prototype of a device to convert the energy of sea waves into electricity.

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A brief introduction to the fractional continuous-time linear systems is presented. It will be done without needing a deep study of the fractional derivatives. We will show that the computation of the impulse and step responses is very similar to the classic. The main difference lies in the substitution of the exponential by the Mittag-Leffler function. We will present also the main formulae defining the fractional derivatives.

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A CMOS analogue circuit for Gaussian noise generation as well as a novel circuit for transforming Gaussian noise into uniform noise, both designed for operating with a supply voltage of 1.5V, are presented. Both circuits are optimized for a 0.35 {\ensuremathμ}m standard CMOS technology using an equation-based design methodology based on genetic algorithms. Electrical simulations demonstrate that high noise amplitudes together with reasonable bandwidths can be achieved with relatively low power dissipation. Potential applications include self-calibration and on-chip self-testing of video-rate analogue-to-digital converters.

A software tool for the analysis of the High-Resolution Electrocardiogram (HR-ECG) for Arrhythmia detection is introduced. New algorithms based on Wavelet analysis are presented and compared with the classic Simson protocol over the P and QRS segments of the Electrocardiogram (EEG). A novel procedure based on a two step wavelet analysis and synthesis is performed in order to obtain a frequency description of the P, T or QRS segments. This frequency ?signature? is useful for the detection of otherwise asymptomatic Arrhythmia patients. The tool has been developed in Matlab, and deployed for a standalone C application.

O desenvolvimento de um pacote de software para lidar facilmente com electrocardiogramas de alta resolução tornou-se importante para pesquisa na área de electrocardiografia. O desenvolvimento de novas técnicas para detecção de potenciais tardios e outros problemas associados a arritmias cardíacas têm sido objecto de estudo ao longo dos anos. No entanto, ainda existe a lacuna de um pacote de software que facilmente permita implementar algumas destas inovadoras técnicas de uma forma integrada, possibilitando avaliar técnicas clássicas como o protocolo de Simson para a detecção de sinais não estacionários (potenciais tardios). Algumas destas inovadoras técnicas envolvem a detecção tempo-frequência usando escalogramas ou a análise espectral usando metodologias wavelet-packet, sendo implementadas no software desenvolvido com flexibilidade e versatilidade suficientes para que futuramente sirva de plataforma de pesquisa para o refinamento destas mesmas técnicas no que toca ao processamento de sinais de electrocardiogramas de alta resolução. O software aqui desenvolvido foi também desenhado de forma a suportar dois tipos de ficheiros diferentes provenientes de outros tantos sistemas de aquisição. Os sistemas suportados são o ActiveTwo da Biosemi e o USBamp da g.tec.

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