Papers by Keyword: Fractal Dimension

Abstract: The fractal dimension of a large group of nano-silica, alumina, titanium oxide, and Gd₂O₃ and Y₂O₃ was calculated by means of original program. Nanopowders of used oxides are created in two main ways, such as evaporation substances by relativistic electron beam and high temperature hydrolysis. The fractal dimension was calculated upon transmission electron microscopy images obtained with different magnification. It was managed to establish that it's possible to make a comparative assessment of the degree of hydrophilicity of the nano-silica's samples by means of attitude fractal dimension to the specific surface.

Abstract: The classification precision of remote sensing image has always been one of the problems to each scholar. The traditional classification method is based on the spectral information. With the advancement of technology, the resolution of remote sensing image is gradually improving, and texture features included are getting rich, so adding texture characteristics to spectral characteristics for image classification can remedy the shortage of only relying on spectral characteristics. This paper uses experimental area of aerial image with 0.5m resolution in Datong, calculates fractal dimension using differential box-counting model, extracts the spatial texture features, and classifies precisely combining spectral characteristics in maximum likelihood method. Through comparing different classification results based on different characteristics, it show that classification accuracy based on combination of texture characteristics and spectral characteristics is more accurate (92% overall accuracy and kappa=0.91) than the one based on single spectral feature (88% overall accuracy and kappa=0.85) and texture feature (69% overall accuracy and kappa=0.65), which verifies the effectiveness of this method.

Abstract: Coal is a natural porous media, its porosity and structural integrity influenced the gas adsorption and desorption characteristics greatly, as well as physical and mechanical properties of coal. Scanning electron microscopy (SEM) is applied to acquire SEM image of four kinds of coal samples at different zoom levels, and the box dimension can be worked out based on the pore preprocessing of SEM images. Then, the numerical value of box dimension is used to describe the development degree of the four kinds of coal sample and four development degrees’ sequence. At last, the intrinsic relevance between fractal dimension and other parameters is analyzed through mathematic method. The results show as follows: coal sample has self-similarity characteristic; the fractal dimension is related to both the total number of pores and porosity degree; the data of the coal pore, analyzed through fractal dimension, are consistent with that through traditional method; what’s more, fractal dimension has more advantages in describing accuracy and simplicity.

Abstract: Based on the spatial land use database of Mingcheng town of Panshi City in Jilin, fractal dimension and stability of land use types are studied by using GIS technology and fractal theory. The land use is classified into 7 types: cropland, garden plot, wood land, water, road land, industrial and mining, residential areas, unused land, and other lands. The fractal dimension for the patches of the land use types is analyzed. Results showed that all the land use types have fractal characteristics and the fractal dimension (D) values vary from 1.1028 to 1.6638. In terms of the land use stability given by the fractal dimension, the order of the land use types from high to low is water, industrial and mining residential areas, cropland, wood land, unused land, road land, garden plot. And land use shape index, fragmentation index and the separation index in the spatial distribution law are largely affected by human activities influence and interference, then it can provided reference for the reason utilizing of land resource.

Abstract: This paper adopted the vacuum sintering technology to prepare titanium fiber porous material with a three-dimensional spatial network fiber backbone and connectivity pore structure. With the help of fractal geometry theory and scanning and digitizing the image, the fractal research of pore-structure in porous titanium fibers is executed and we studied the influence of adopting the box-counting dimension method to calculate the fractal dimension. Additionally, we determined the quantitative relationship between fractal dimension and the porosity of the porous in titanium fiber, while described the physical meaning of the fractal dimension.

Abstract: Conventional characterization methods of grinding surface using surface roughness parameters, e.g., Ra, depend on either the resolution of the measuring instrument or the length of the sample. But fractal dimension (FD) as a scale-independent fractal parameter is effective to evaluate the ground surface at any length scale and represent lots of surface phenomenon at its relevant length scales. In this paper, a three-dimensional (3D) box-counting fractal analysis method is used to investigate ground surface morphology of monocrystal sapphire by calculating 3D fractal dimension of the ground surface. The results obtained show that fractal dimension decreases with the increasing surface roughness. For the ground surface with higher fractal dimension, its microtopography is more exquisite with minor defects. Once the fractal dimension become smaller, deep cracks and pronounced defects are exhibited in ground surface. Moreover, the ground surface obtained in ductile mode has much higher fractal dimension than that in brittle mode. Therefore, the fractal analysis method has the potential to reveal the ground surface characteristics of monocrystal sapphire.

Abstract: Fractal analysis of plant spatial patterns has been used to characterize the regressive ecological succession. The fractal dimension is used as a variable to help in charactering specific patterns in different kind of trees. A computational program was developed to process, analyze and extract the features of images of tree branch structure. Results are presented from four experiments to determine plant species from the color image of tree branch growth.

Abstract: Monocrystal sapphire ground surfaces obtained by ductile mode and brittle mode are analyzed in this paper. A two dimension (2D) fractal properties of different ground surfaces are calculated and analyzed by a box-counting fractal method. The results show that the fractal dimension (FD) in parallel grinding direction can imply the material removal mode, especially for the surfaces with a similar roughness Ra obtained in different material removal modes. The ground surface obtained in ductile mode has much higher FD in the parallel direction than that in brittle mode. For the surface with high FD in parallel direction, its profile is more exquisite and surface quality is better. For the surface with a small FD in the parallel direction, a deeper crack and more pronounced defects occur. On the other hand, the profile FD distributions can reflect the anisotropic features of monocrystal sapphire ground surfaces. Therefore, the fractal analysis method has the potential to reveal precisely and comprehensively the ground surface characteristics of monocrystal sapphire.

Abstract: In order to solve complex problems of traditional methods used to evaluate the rock fracability, the relationship between fractal dimension, rock brittleness and fracture density these three parameters was studied. The multiple linear regression is reasonable through nine kinds cores. The regression coefficients demonstrate both rock brittleness and surface fracture density play positive roles on fractal dimension value, the larger they are, the better the fracability. Therefore, the two parameters can be converted to consider only one parameter that is the fractal dimension of rock. The larger the fractal dimension, the better the fracability is, that is using fractal dimension represents brittle index and surface density to participate in fracability evaluation.

Abstract: Five kinds of powder activatedcarbons were studied to investigate the removal of SO₂ from flue gasin a fixed bed reactor. The fractal dimension of activated carbon was determined by N₂ adsorption isothermat 77Kand SO₂ adsorptioncapacity was correlated with thefractal dimension. The results show thatthe activated carbons prepared from different precursors by differentactivation methods have different fractal dimension. Big differences in SO₂ adsorption capacity are found between fivekinds of activated carbons. SO₂ adsorption capacity increases with the fractaldimension increasing. The results indicate that the fractal dimension could be used as a indicator of SO₂removal capacity on powder activated carbon.