Papers by Keyword: Fractal Dimension

Abstract: The characterization of guide way joint surface micro-topography is very important for the study of real guide way joint surface. Based on fractal theory, fractal characteristics of rough surface are investigated. The 3D surface topography of specimen which is closed to machine tool guide way both in material and processing condition is obtained by atomic force microscope (AFM). The structure function method is employed to gain fractal dimension and the analysis of fractal characteristics. The results show that meet the processing conditions, the guide way joint surface in the region which can scale show good linear relationship and has obvious fractal.

Abstract: To the energy limited of nodes and imbalance energy consuming among nodes, this paper propose a algorithm of wireless sensor networks based on network building and complexity calculating, analyzed the energy consumption ration between classical cluster algorithm and new strategy. The algorithm uses a method that calculating each cluster complex and adjusting the structure of clusters if which clusters has high degree complexity. The analysis of the results shows that the algorithm improves energy efficiency and the life time of sensor network.

Abstract: With dry sieving and wet sieving methods, we studied the distribution characteristics and stability of the aggregates in the typical orchard soils with different cultivation years in northern China under long-term freezing-thawing conditions. The results show that: the contents of the aggregates with particle size above 10 mm or between 0.25 and 10 mm are significantly increased with cultivation years and annual growth rates were respectively 1.28% and 0.078%. Fractal dimension in the orchard soils was gradually decreased and lower than that in uncultivated area near the orchard in corresponding cultivation year. MWD of orchard soils shows annual increasing trend of 0.76%. The content of the water stable macro aggregates in orchard soils was increased with the cultivation years and was about 11.65%-20.18% higher than that of uncultivated soils near the orchard. Average annual growth of orchard soils was 0.37%. Fractal dimension was decreased year by year on the water stable macro aggregates. MWD of the water stable macro aggregates was significantly greater than that of uncultivated soils near the orchard and increased with cultivation years. Aggregate destruction rate was gradually decreased to 31.61% of that in the 60^th year and annual average decrease rate was 0.91%. Soil bulk density was gradually decreased.

Abstract: Heterogeneity has been considered as a critical character of the rock structure. Fractal dimension makes it applicable to describe the complexity structure quantitatively. The evolution of rock heterogeneity has been investigated by surface fractal dimension parameter and covering projection method. The fractal behavior of meso-structure of the rock corroded by acid mine drainage was obviously observed. The fractal dimension of the rock structure was chosen to describe the heterogeneity of the rock structure attacked by Acid Mine Drainage. It observed that the fractal dimension of the rock structure increased and the rock heterogeneity became more distinctive during the process of attack.

Abstract: In this paper a new method is proposed for intelligent sort of battery from waste paper based on Invariant Moments and Fractal Dimension (IMFD). In IMFD, a new distinctive feature that based on the edge contours is extracted to describe the target picture. At first invariant moments technique is used to extract Hus seven moments as the global descriptors from the target image. Then the fractal dimensions are extracted as local invariant descriptors by using Fractal Dimension. At last, a combing descriptor is built according the distinctive feature, which combines the global descriptor and the local descriptor together. The features are highly distinctive, and can be matched with high probability against a large database of features. The practical tests performed in this article show that the proposed method has a significant effect on increasing the stability, the accuracy of classification, and also can effectively against the huge-information during the image processing.

Abstract: The frequency and time of precipitation can influence the storage, allocation and management of water resources. But the precipitation frequency becomes more random and the precipitation process becomes more complexity due to the climate change and human activities, which increases the difficulty of technology and management. In this research, the fractal dimension based on Continuous Wavelet Transform (CWT) as the index of the precipitation complexity is applied to describe the precipitation process; using it, the complexity distributions of different precipitation processes in Liu-Kuang zone of Qingzhang basin China in different periods is illuminated respectively. The result indicates that in research region: (1) the annual precipitation frequency in the late period is less than that in the early period; (2) the urbanization and human activities increase the precipitation frequency. This result can reflect the frequency change of precipitation in changing environment and provide reference for the decision-making of water resources management in the local basin.

Abstract: CaO-Al₂O₃-P₂O₅cementitious material (PAC) is a type of new developed hydraulic cement, which has excellent cementitious performance and mechanical property. In cement based materials, the pore structure of hardened cement paste has a significant effect on their performance, such like strength, permeability and durability. In the current paper, pore structure parameters of hardened PAC paste samples in five different curing stages were measured respectively by MIP (Mercury Intrusion Porosimetry). The pore fractal features (pore volume, pore area, porosity) were investigated with fractal theory. Results showed that the porosity of hardened PAC paste does not exactly decline with elongation of curing age and increase of compression strength. The PAC pastes pore structures have typical fractal nature which changes with curing age and pore diameter distribution. The fractal feather of hardened PAC paste can be effectively understood by using porosity fractal dimension.

Abstract: Basing on fractal geometry theory, establish fractal calculation model in effective stress, analyze and discuss the relationship between microstructure of porous medium and effective stress, reveal the influence law of the latter on the former. The results of the study show that the fractal calculation model of effective stress can describe the relationship between them. With the increase of effective stress, the fractal dimension of porous medium increases exponentially, porosity and pore number in porous medium decrease exponentially and mean radius of pore decreases.

Abstract: A 3D finite element model (FEM) of metal cutting was constructed based on the thermal-mechanical coupling theory. The cutting process of Sialon ceramic tools turning Inconel 718 was simulated and experimented. The effect of cutting speed, feed rate and depth of cut on the cutting force was analyzed. According to the correlation characteristics between the data points, the fractal characteristics of cutting forces in the cutting process were also investigated. The results showed that the cutting speed had a great effect on the fractal dimension of cutting force. The simulation results were in good agreement with the experimental findings. It was concluded that the minimum fractal dimension of cutting force was obtained at v=230 m/min under these experiment conditions. The fractal analysis is a simple and powerful tool for quantifying the stability of cutting process. The finding of this research is valuable for future practical implementation.

Abstract: With the rapid development of city, many large and medium-sized cities sprawl in urban space,triggering a series of socio-economic issues related to land-use. Based on RS and GIS, selected Kunming as study area for its typical representation of Yunnan plateau mountain cities, used the method of spatial quadrant orientation analysis, obtained the number and structure of construction land expansion in specific direction of study area in period of two different years, and calculated the intensity index and fractal dimensions of the urban expansion. Finally, according to local conditions, spatial expansion variations features of Kunming were analyzed systematically.