Manuel Duarte Ortigueira

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Fractional centred differences and derivatives definitions are proposed generalising to real orders the existing ones valid for even and odd positive integer orders. For each one, suitable integral formulations are obtained. The computations of the involved integrals lead to new generalisations of the Cauchy integral derivative. To compute this integral, a(More)
The 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(More)
This paper addresses the ARMA spectral estimation problem, using as starting point, the Double Levinson Recursion Formulation proposed by Carayannis and al. in 1980 , to compute the AR parameters of an AREA model. A theoretical analysis of the Double Levinson Recursion Formulation led to the derivation of a theorem from which the correct AR and MA orders(More)
1 UNINOVA and DEE, Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa, Campus da FCT da UNL, Quinta da Torre, 2829-516 Caparica, Portugal 2 INESC ID, Rua Alves Redol, 9, 2o, 1000-029 Lisboa, Portugal 3 L2F INESC ID, Rua Alves Redol, 9, 2o, 1000-029 Lisboa, Portugal 4 Academia Militar, Rua Gomes Freire, 1150-175 Lisboa, Portugal Abstract – In(More)