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Multifractal Estimators of Long Range Dependences |
Danuta Makowiec |
Gdansk University, Institute of Theoretical Physics and Astrophysics, (IFTiA UG), Wita Stwosza 57, Gdańsk 80-952, Poland |
Abstract |
Multifractal approach is a generalization of fractal techniques. It offers an attractive and compact frame to qualify and quantify multiscaling aspects immersed in any system represented by time series. A lot of simulations were performed to validate numerical procedures (Abry et al., Stoev et al., Oświęcimka et al., Lashermes et al., Makowiec et al. 2009, Makowiec et al. 2010). However available tools still seem to be not powerful enough to discern reliably all specificity of the real data organization. One can find a lot of advice how to overcome possible traps. For example, it is advised to investigate series that are long enough (Oświęcimka et al.), to use parallelly tools which are of different numerical origin (Kantelhardt). As a good rule of thumb is to question results if a multifractal spectrum is concentrated at h=1 or h=0 (Gao et al.). Finally, it is said that specific knowledge about the phenomenon from which a signal is analyzed should be carefully taken into account (Veitch et al., Stoev et al.). Therefore multifractal estimates demand special protocols describing how to proceed with systematic errors of numerical methods used, and how to extract reliable fractal characterization of a given data. We want to present the method which consists in working together on two multifractal spectra received numerically from a given signal. The first spectrum describes the signal itself while the second spectrum is calculated for the integrated signal. By such approach each signal is analyzed twice: if it is a stochastic walk (a direct signal), and if it is a noise (when integrated). Moreover, the scaling options for the partition functions are kept firmly within the particular time interval to detect phenomena related to that time interval. Our proposition bases ob wide simulation experiments in which the software of Physionet (i.e., multifractal.c and dfa.c modified to receive the multifractal scaling) was applied to synthetic data. Abry B, Jaffard S and Lashermes B 2004, Revisiting scaling, multifractal, and multiplicative cascades with wavelet leader lens Optic East, Wavelet Applications in Industrial Applications II vol. 5607 103, Philadelphia, USA, 2004. Gao J, Cao Y, Tung W-W, Hu J 2007, Multiscale analysis of complex time series. Integration of Chaos and random Fractal Theory, and Beyond (John Wiley\& Sons, Inc). Kantelhardt J W 2009, Fractal and multifractal time series in Encyclopedia of Complexity and Systems Science Meyers R A(Ed.), Springer. Lashermes B, Roux S G, Abry P and Jaffard J 2008, Comprehensive multifractal analysis of turbulent velocity using the wavelet leaders Eur.Phys.J B 61 201.Makowiec D, Dudkowska A, Gałąska R and Rynkiewicz A 2009, Multifractal estimates of monofractality in RR-heart series in power spectrum ranges Physica A 388 3486. Makowiec D and Fuliński A 2010, Multifractal Detrended Fluctuation Analysis as the Estimator of Long-Range Dependence. Acta Phys. Pol. B 41 1025. Oświęcimka P, Kwapień J and Drożdż Z 2006, Wavelet versus detrended fluctuation analysis of multifractal structures Phys. Rev. E 74 016103. Stoev S, Taqqu M S, Park Ch and Marron J S 2005, On the wavelet spectrum diagnostic for Hurst parameter estimation in the analysis of Internet traffic Comp.Networks 48 423. Veitch D, Hohn N and Abry P 2005, Multifractality in TCP\ IP traffic: the case against Comp. Networks 48 293. |
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Presentation: Oral at 5 Ogólnopolskie Sympozjum "Fizyka w Ekonomii i Naukach Społecznych", by Danuta MakowiecSee On-line Journal of 5 Ogólnopolskie Sympozjum "Fizyka w Ekonomii i Naukach Społecznych" Submitted: 2010-10-15 16:24 Revised: 2010-10-15 16:50 |