نتایج جستجو برای: power law frequency fractal model

تعداد نتایج: 2991823  

2003
A. Ostling

Power-law relationships appear to characterize many patterns observed in ecology, from the level of individuals to the level of ecosystems (Calder 1984, Gaston and Blackburn 2000). These power laws often hold over scale ranges sufficiently large to justify the search for a unifying theoretical framework explaining the relationship between these patterns. A promising avenue for discovering such ...

2005
W. Chen

The absorption of acoustic wave propagation in a broad variety of lossy media is characterized by an empirical power law function of frequency, y ω α0 . It has long been noted that exponent y ranges from 0 to 2 for diverse media. Recently, the present author developed a fractional Laplacian wave equation to accurately model the power law dissipation, which can be further reduced to the fraction...

2009
L. Egghe

Two-dimensional informetrics is defined in the general context of sources that produce items and examples are given. These systems are called “Information Production Processes” (IPPs). They can be described by a size-frequency function f or, equivalently, by a rank-frequency function g. If f is a decreasing power law then we say that this function is the law of Lotka and it is equivalent with t...

2005
José Gaite

– We examine the proposal that a model of the large-scale matter distribution consisting of randomly placed haloes with power-law profile, as opposed to a fractal model, can account for the observed power-law galaxy-galaxy correlations. We conclude that such model, which can actually be considered as a degenerate multifractal model, is not realistic but suggests a new picture of multifractal mo...

Journal: :Physical review. E, Statistical, nonlinear, and soft matter physics 2015
B B Cael Bennett Lambert Kelsey Bisson

Studies over the past decade have reported power-law distributions for the areas of terrestrial lakes and Arctic melt ponds, as well as fractal relationships between their areas and coastlines. Here we report similar fractal structure of ponds in a tidal flat, thereby extending the spatial and temporal scales on which such phenomena have been observed in geophysical systems. Images taken during...

2002
Donald L. Turcotte

A fractal (power-law) distribution is the only statistical distribution applicable to a scale-invariant process. One of the major problems in petrology is the distribution of trace elements in the Earth’s crust. Extreme values of this distribution result in ore deposits. There is accumulating observational evidence that tonnage–grade statistics of ore deposits are often fractal (powerlaw). Rayl...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2002
Donald L Turcotte Bruce D Malamud Fausto Guzzetti Paola Reichenbach

We consider the frequency-size statistics of two natural hazards, forest fires and landslides. Both appear to satisfy power-law (fractal) distributions to a good approximation under a wide variety of conditions. Two simple cellular-automata models have been proposed as analogs for this observed behavior, the forest fire model for forest fires and the sand pile model for landslides. The behavior...

2001
Bruce G. Elmegreen

Three-dimensional fractal models on grids of ∼ 200 pixels are generated from the inverse Fourier transform of noise with a power law cutoff, exponentiated to give a log normal distribution of density. The fractals are clipped at various intensity levels and the mass and size distribution functions of the clipped peaks and their subpeaks are determined. These distribution functions are analogous...

2004
Agnès Desolneux Bernard Sapoval Andrea Baldassarri A. BALDASSARRI

Classically, percolation critical exponents are linked to the power laws that characterize percolation cluster fractal properties. It is found here that the gradient percolation power laws are conserved even for extreme gradient values for which the frontier of the infinite cluster is no more fractal. In particular the exponent 7/4 which was recently demonstrated to be the exact value for the d...

Journal: :Physical review. E, Statistical, nonlinear, and soft matter physics 2001
H Qi J Ma P Z Wong Pz

We report a numerical study of van der Waals adsorption and capillary condensation effects on self-similar fractal surfaces. An assembly of uncoupled spherical pores with a power-law distribution of radii is used to model fractal surfaces with adjustable dimensions. We find that the commonly used fractal Frankel-Halsey-Hill equation systematically fails to give the correct dimension due to cros...

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