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On the HHT, its problems, and some solutions
Ortigueira, M.D.; Rato, R.T.; Batista, A. G.Mechanical Systems and Signal Processing, Vol.22, Number 6 ; The empirical mode decomposition (EMD) is reviewed and some questions related to its effective performance are discussed. Its interpretation in terms of AM/FM modulation is done. Solutions for its drawbacks are proposed. Numerical simulations are carried out to empirically evaluate the proposed modified EMD.
On the relation between the fractional Brownian motion and the fractional deriv...
Ortigueira, M.D.; Batista, A. G.Physics Letters A, vol. 372; Issue 7 ; The definition and simulation of fractional Brownian motion are considered from the point of view of a set of coherent fractional derivative definitions. To do it, two sets of fractional derivatives are considered: (a) the forward and backward and (b) the central derivatives, together with two representations: generalised difference and integral. It is shown that for thes...
ECG wave detector and delineation with wavelets
Ortigueira, M.D.; Alves, L. B.; Batista, A. G.; Pinto, I. V.Proceedings of the International Conference on Computational Intelligence in Medicine Healthcare, CIMED 2005, Costa da Caparica, June 29 - July 1, 2005 ; Efficient R wave detection is a crucial preprocessing step of most of the ECG signal analysis . Likewis e, ECG delineation comprising P wave and QRS complex, is required for ECG processing, namely in High- Resolution Electrocardiography (HR-ECG). We have perf...
A fractional linear system view of the fractional brownian motion
Ortigueira, M.D.; Batista, A. G.Nonlinear Dynamics, Vol. 38 ; A definition of the fractional Brownian motion based on the fractional differintegrator characteristics is proposed and studied. It is shown that the model enjoys the usually required properties. A discrete-time version based in the backward difference and in the bilinear transformation is considered. Some results are presented.
Time-frequency and time-scale characterisation of the beat-by-beat high-resolut...
Ortigueira, M.D.; Batista, A. G.; Rodrigues, J. MachadoProceedings of the Sixth Portuguese Conference on Bioemedical Engineering faro, Portugal ; Time-Frequency and Time-Scale distributions of sequential ST segments the High-Resolution Electrocardiogram, are represented using both the Morlet Wavelet based scalogram and the Zhao-Atlas-Marks representation. Resolution and representation readability, concerning the Ventricular Late Potentials are compared. The beat-t...
A signal processing view of differintegration
Ortigueira, M.D.; Batista, A. G.Proceedings of the European Control Conference, ECC’01, Porto, Portugal, September 2001 ; The fractional differintegration problem is treated from the Signal Processing point of view. A brief review of the Laplace transform approach to differintegration is done. The continuoustime/ discrete-time system conversion is discussed and presented a Grünwald-Letnikov integration.
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