Abstract
Two features should be kept in mind when the parametric spectrum analysis, such as AR or MEM method, is applied to the turbulence in the aorta. Firstly, the broad frequency band width spectrum is the main interest in turbulence research. Spectra of this kind are apt to be regarded as originated from noises rather than a signal of interest in other fields. Secondly, in an unsteady stochastic process, only ensemble average technique is strictly valid for the definition of statistical measures. Spectral calculations, therefore, should be based on an ensemble average, while parametric methods so far reported are not.
In the present study, a method of spectral calculation based on the ensemble average technique, which is a natural expansion of the Burg's maximum entropy method, is proposed. This method is applied to a set of numerical simulation data which simulates turbulent velocity fluctuations data measured in the canine aorta with a hot-film anemometer. Autoregressive order of the spectral calculation is chosen by the minimum AIC (Akaike's Information Criterion) method. It is shown that the proposed method has a very good performance in the short time quasi-steady spectral analysis of the turbulence in the aorta.
