Fractals 

About: Fractals is an academic journal published by World Scientific. The journal publishes majorly in the area(s): Fractal & Computer science. It has an ISSN identifier of 0218-348X. Over the lifetime, 2531 publications have been published receiving 31589 citations.

Estimators for long-range dependence: an empirical study

Abstract: Various methods for estimating the self-similarity parameter and/or the intensity of long-range dependence in a time series are available. Some are more reliable than others. To discover the ones t...

Some fractal characters of porous media

Abstract: In this paper, a unified model for describing the fractal characters of porous media is deduced. The theoretical predictions from the proposed unified model are compared with those from the previous models and from the box-counting method. The results from the proposed model are found to be in good agreement with both the previous models and box-counting method. The results also indicate that the proposed unified model is applicable to both the exactly and statistically self-similar fractal media. A statistical property of porous media is also described based on the basic fractal theory and technique. A criterion, for determining whether a porous medium can be characterized by fractal theory and technique or not, is proposed based on the fractal statistical property.

Multifractal Cascade Dynamics and Turbulent Intermittency

Abstract: Turbulent intermittency plays a fundamental role in fields ranging from combustion physics and chemical engineering to meteorology. There is a rather general agreement that multifractals are being very successful at quantifying this intermittency. However, we argue that cascade processes are the appropriate and necessary physical models to achieve dynamical modeling of turbulent intermittency. We first review some recent developments and point out new directions which overcome either completely or partially the limitations of current cascade models which are static, discrete in scale, acausal, purely phenomenological and lacking in universal features. We review the debate about universality classes for multifractal processes. Using both turbulent velocity and temperature data, we show that the latter are very well fitted by the (strong) universality, and that the recent (weak, log-Poisson) alternative is untenable for both strong and weak events. Using a continuous, space-time anisotropic framework, we th...

1/f NOISE IN A TRAFFIC MODEL

Abstract: One-dimensional traffic flow is simulated by a cellular-automaton-type discrete model. As we increase the car density, the model shows a phase transition between a jam phase and a non-jam phase. By adding random perturbations we found a 1/f power spectrum in the jam phase, whereas a white noise is observed in the non-jam phase.

Multifractal spectra as a measure of complexity in human posture

Abstract: Human posture is the result of a complex control system. The joint output of several physiological — most likely nonlinearly interacting — processes leads to constant correctional movements which enable humans to stand upright. These correctional body movements reflect features of the underlying control mechanisms and have recently been shown to be multifractal processes. We analyze the movements of healthy quiet standing persons by means of wavelet-based multifractal spectra. We show that the functional form of these spectra depends on the mode of balance control. We compare the findings from a group of healthy persons to a group of patients suffering from balance disorders. As the main result we find that if balance control inputs, such as visual cues or tactile information are reduced, the dominant fractal exponent becomes smaller and the range of fractal exponents strongly narrows. We suggest to use a set of multifractal spectrum parameters as a "measure of complexity."