Papers by Keyword: Fractal Dimension

Abstract: The fractal characteristics of the surface cracks and the damage evolution process of rubber concrete beams under concentrated load are studied. The experimental conclusions show that there exists a quantitative relationship between the fractal dimension and the mechanical properties. The fractal dimension of surface-crack of the rubber concrete beams is able to act as a damage feature index to reflect the damage degree of them effectively. In investigating the crack evolving process of the rubber concrete beams, fractal geometry provides a new technique for the structural health monitoring and the safety evaluation.

Abstract: A fractal model to simulate cement paste internal pore structure, and on this basis deduce that fractal dimension is D and the corresponding pore is r, the relationship between porosity is P. MIP was measured test. Then calculated the different ages of the fractal dimension of cement and concrete compressive strength, tensile strength and permeability coefficient. The results showed that: compressive strength, permeability and fractal dimension has a good correlation. Whey in cement in the process of hydration of cement products continue to fill the pores, making the compressive strength increased 70%, permeability is declining.

Abstract: A fractal model simulate the internal structure of the sludge, and on the model deduce that fractal dimension is D and the corresponding pore is r, the porosity is P. Determine the rate in the air-blast and microwave drying and calculate its different fractal dimension under different ages. The results showed that: the fractal dimension and its rate of water loss has a good correlation. Fractal dimension can describe a certain amount of sludge pore channels and internal cell rupture can cause that which would accelerate the evaporation of bound water. Microwave and the excessive energy of air-blast can be caused by temperature changes in the structure of the sludge that could change the structure of sludge.

Abstract: The complexity of Groundwater dynamic was determined based on the fractal dimensions of groundwater depth sequence of all farms in Jiansanjiang calculated in Grassberger-Procaccia algorithm. It is showed that groundwater dynamic in Jiansanjiang is of certain complexity for fractal dimensions of all wells greater than 1. The complexity of groundwater in Jiansanjiang has a significant spatial variance structure characterized with the complexity of groundwater dynamic in the northwest lower than that in southeast, which indicates that the groundwater system in the southeast fluctuates more strongly and affected by natural and human disturbances more seriously.

Abstract: Focusing on the damage detection using the fractal dimension analysis in plates, this study begins by giving a fractal dimension scanning method for beams. Then extend the algorithm to the plates by degrading the plate mode shape into transverse and longitudinal directions. With the affine transformation, the proposed method overcomes the incapability of identifying damage when using the higher-order mode shapes of the existing fractal dimension methods. Numerical results show that different types of cracks, crack locations and lengths can be detected using this method.

Abstract: The hydrological processes are becoming more and more complex. Fractal dimension is one of the important measurements of complexity. This paper utilizes wavelets transform technique to calculate the fractal dimension of runoff for eight stations (Zhimenda, Shigu, Ganzi, Yajiang, Guili, Luning, Xiaodeshi, Pingshan ) in the Jinsha River Basin. The results show: the runoff series in the Jinsha River Basin is fractal; the approach for estimating the fractal dimension by using wavelet transform coefficients is feasible and effective; the fractal dimension of runoff reflect the influence of factors on the runoff.

Abstract: New-to-old concrete freeze-thawing durability affects the safety and normal service of structure. In this paper, the freeze-thawing resistance of new-to-old concrete with different rough substrate surfaces was studied. The roughness of substrate surface was characterized by fractal dimension. Test results show that freeze-thawing damage of new-to-old concrete has two stage changes: first stage, freeze-thawing damage increases rapidly, mainly caused by the damage of interface; second stage, freeze-thawing damage increases slower, mainly reflects damage of substrate and overlay. Compared with smooth surface, rough surface can significantly improve freeze-thawing resistance of new-to-old concrete. In a certain range, with the increase of fractal dimension, the freeze-thawing resistance improves. When the fractal dimension is beyond the range, the freeze-thawing resistance impairs while the fractal dimension increases. A freeze-thawing damage model applied to new-to-old concrete is proposed, and a good correlation is found between the model and experimental results.

Abstract: The estimation and characterization of laser cutting heavy plate surface topography is very significant to the study on the formation mechanism of laser cutting surface and the relationship between machined surface formation and the processing parameters. The article characterizes the surface topography of the laser cutting heavy plate based on the fractal geometry theory, use box-counting method to calculate the fractal dimension of the laser cutting heavy plate surface. The results show the laser cutting heavy plate surface of low carbon steel has a obvious fractal feature, the fractal dimension of laser cutting surface range from 1.283 to 1.395 in a certain scale, the laser cutting surface topography is relatively complex, the relation between Fractal dimension D and surface roughness Ra are not linear correspondence, and then the surface topography of laser cutting heavy plate can be comprehensively estimated in accordance with D and Ra.

Abstract: Based on fractal theory and WZ model of gas discharge, The spacial temporal behavior in discharge process from Thundercloud to Ground was simulated efficiently. Moreover, we discussed the probability index and the field intensity of the discharge path and their influence on the fractal dimension and the discharge path., and pointed out that the research should focus on the relation between the probability index and the fractal dimension.

Abstract: The structures of nonwovens are so nonlinear and out-of-order that traditional methods can hardly measure it. There exist several basic parameters to characterize it, such as thickness, grammage, average density and pore characteristics etc.. It is necessary to find one integrated parameter to characterize nonwovens, and fractal approach seems to be a useful tool. In this paper, the fractal dimension is implemented to describe the structure of nonwovens. And then the relationship between the fractal dimension and several basic structural parameters are built up.