نتایج جستجو برای: power spectrumarea fractal analysis
تعداد نتایج: 3217380 فیلتر نتایج به سال:
This work proposes the application of fractal descriptors to the analysis of nanoscale materials under different experimental conditions. We obtain descriptors for images from the sample applying a multiscale transform to the calculation of fractal dimension of a surface map of such image. Particularly, we have used the Bouligand-Minkowski fractal dimension. We applied these descriptors to disc...
Dynamical systems in nature exhibit selfsimilar fractal fluctuations and the corresponding power spectra follow inverse power law form signifying long-range space-time correlations identified as self-organized criticality. The physics of selforganized criticality is not yet identified. The Gaussian probability distribution used widely for analysis and description of large data sets underestimat...
Horizontal distribution of the copepod Neocalanus cristatus was shown to be fractal on the scale between tens of meters and over 100 km. The fractal dimensions ranged between 1.68–1.89, significantly higher than those of oceanic turbulence and phytoplankton distribution. 1. Introduction Heterogeneity in the horizontal distribution of zooplankton has been recognized for many years (e.g. Hardy, 1...
Our purpose is to describe some recent progress in applying fractal concepts to systems of relevance to biology and medicine. We review several biological systems characterized by fractal geometry, with a particular focus on the long-range power-law correlations found recently in DNA sequences containing noncoding material. Furthermore, we discuss the finding that the exponent alpha quantifying...
in this work, sio2 –zro2 mixed oxides was prepared by the polymeric sol–gel route. the characterization of pore structure, which determines the permeation process of membrane, is of great importance. so far, most investigations have focused on such pore structure as specific surface area and pore size distribution, but the surface fractal, the important parameter reflecting the roughness of por...
Slant-discrimination thresholds were measured for textures with the property that their power spectra, when log transformed, are inversely proportional to log spatial frequency: P(f) alpha f-beta. As the exponent beta changes from high values to low values, the slope of the power spectrum of the image decreases. As the parameter passes through values in the fractal range the resulting texture c...
BACKGROUND Measures of EEG during ECT, for example, smaller post-seizure fractal dimension have predicted antidepressant response. The earlier study on this subject used bilateral ECT. This study aims to examine if this finding holds good even for unilateral ECT, using both fractal dimension and spectral power analysis of EEG. METHODS Fifty-one right-handed, drug-free patients with major depr...
A fractal is an object or a structure that is self-similar in all length scales. Fractal geometry is an excellent mathematical tool used in the study of irregular geometric objects. The concept of the fractal dimension, D, as a measure of complexity is defined. The concept of fractal geometry is closely linked to scale invariance, and it provides a framework for the analysis of natural phenomen...
Electrocortical group neuron activity describe changes in neurotransmision cause by different factors. Such changes could by qualitative described by spectral analysis of electrocortical activity as a variation of relative spectral power in different frequency ranges. We used fractal dimension to compare treated animals with control to quantitativily describe degree of pathophysiological state....
power transformers are important equipments in power systems. thus there is a large number of researches devoted of power transformers. however, there is still a demand for future investigations, especially in the field of diagnosis of transformer failures. in order to fulfill the demand, the first part reports a study case in which four main types of failures on the active part are investigate...
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