Ktonas, PY, Golemati S, Xanthopoulos P, Sakkalis V, Ortigueira MD, Tsekou H, Zervakis M, Paparrigopoulos T, Soldatos CR.
2007.
Potential dementia biomarkers based on the time-varying microstructure of sleep EEG spindles. 2007 29th Annual International Conference of the IEEE Engineering in Medicine and Biology Society. :2464–2467.
AbstractThe time-varying microstructure of sleep EEG spindles may have clinical significance in dementia studies. In this work, the sleep spindle is modeled as an AM-FM signal and parameterized in terms of six parameters, three quantifying the instantaneous envelope (IE) and three quantifying the instantaneous frequency (IF) of the spindle model. The IE and IF waveforms of sleep spindles from patients with dementia and normal controls were estimated using the time-frequency technique of complex demodulation (CD). Sinusoidal curve-fitting using a matching pursuit (MP) approach was applied to the IE and IF waveforms for the estimation of the six model parameters. Specific differences were found in sleep spindle instantaneous frequency dynamics between spindles from dementia subjects and spindles from controls.
Ortigueira, MD, Serralheiro AJ.
2007.
Pseudo-fractional ARMA modelling using a double Levinson recursion. IET Control Theory & Applications. 1:173., Number 1: IEEE
AbstractThe modelling of fractional linear systems through ARMA models is addressed. To perform this study, a new recursive algorithm for impulse response ARMA modelling is presented. This is a general algorithm that allows the recursive construction of ARMA models from the impulse response sequence. This algorithm does not need an exact order specification, as it gives some insights into the correct orders. It is applied to modelling fractional linear systems described by fractional powers of the backward difference and the bilinear transformations. The analysis of the results leads to propose suitable models for those systems.
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