نتایج جستجو برای: fractal dimension
تعداد نتایج: 133816 فیلتر نتایج به سال:
PURPOSE This study describes how to identify the coincidence of desired planning isodose curves with film experimental results by using a mathematical fractal dimension characteristic method to avoid the errors caused by visual inspection in the intensity modulation radiation therapy (IMRT). METHODS AND MATERIALS The isodose curves of the films delivered by linear accelerator according to Pla...
The difficulty to obtain a stable estimate of fractal dimension for stochastic fractal (e.g., urban form) is an unsolved issue in fractal analysis. The widely used box-counting method has three main issues: 1) ambiguities in setting up a proper box cover of the object of interest; 2) problems of limited data points for box sizes; 3) difficulty in determining the scaling range. These issues lead...
The fractal and self-similarity properties are revealed in many real complex networks. However, the classical information dimension of complex networks is not practical for real complex networks. In this paper, a new information dimension to characterize the dimension of complex networks is proposed. The difference of information for each box in the box-covering algorithm of complex networks is...
and Applied Analysis 3 where k is a constant, α is the fractal dimension, L0 is the smallest measure, and u t is the distance between two points in the porous media. The distance between two points in a discontinuous space is
BACKGROUND The purpose of this study was to quantify the heterogeneous distribution of echodensities in the pericardial fluid of patients with tuberculous pericarditis using echocardiography and fractal analysis, and to determine whether there were differences in the fractal dimensions of effusive-constrictive and effusive non-constrictive disease. METHODS We used fractal geometry to quantify...
The calculation of dimensions is a useful tool to quantify structural information of artificial and natural objects. There are some types of dimension [9]: the Euclidean one, the Hausdorff-Besicovitch dimension, and so on. We are going to work with the fractal dimension in the special case of text documents. There are many objects which fractal dimension cannot be determined analytically, but t...
In this paper, a pilot study regarding carotid atherosclerotic plaque instability using B-mode ultrasound (US) images was carried out. The fractal dimension of plaques obtained from ten symptomatic subjects (i.e., subjects having experienced neurological symptoms) as well as from nine asymptomatic subjects, was estimated using a novel method, called the kth nearest neighbour (KNN) method. The r...
Fractal analysis has been applied in many fields since it was proposed by Mandelbrot in 1967. Fractal dimension is a basic parameter of fractal analysis. According to the difference of fractal dimensions for images, natural landscapes and urbanscapes could be differentiated, which is of great significance. In this paper, two methods were used for two types of landscape images to discuss the dif...
“When we say that space has the dimensions three, what do we mean? If to divide a continuum C it suffices to consider as cuts a certain number of distinguishable points, we say that this continuum is of dimension one. If, on the contrary, to divide a continuum it suffices to use cuts which form one or several continua of dimension one, then we say that C is a continuum of dimension two. If cuts...
On the basis of similar structure of solution for a second-order linear differential equation’s boundary value problem, and our analysis of the relationship between this similar structure and its kernel function, the differential equation, and the boundary conditions, we propose a new simple solution—similar constructive method of solution (SCMS)—and sum up its detailed steps. We set up a porou...
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