Papers by Keyword: Fractal Dimension

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Authors: Guang Ming Zheng, Jun Zhao, Xin Yu Song, Xiang Cheng
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.
Authors: Zheng Wang, Wei Yun Xie, Lu Wang, Jian Xiong Liu
Abstract: The fractal dimension is a basic parameter to indicate the random self-similar shape and phenomena. The damage process is the result of co-effect of all the cracks, which shows a good collective behavior and random statistical complexity. The collective evolution of short fatigue cracks was experimentally studied through cylindrical specimens with annular notches with respect to the variation of nominal strain amplitudes. The maximum between-class variance method (Otsu's method) was adopted for the denoised image binarization and the fractal dimensions were obtained. The results show that: the collective behavior of short fatigue cracks possesses good fractal characteristics; as the evolution of the short fatigue cracks, fractal dimensions underwent two stages: a primary stage of high growth speed, a relatively stable stage of almost to zero growth speed; the critical cut-off point at about 30% of the fatigue life according to the experimental results can be used to represent a threshold value of the MSC and PSC of short fatigue cracks.
Authors: Jie Xu, Giusepe Lacidogna
Abstract: A fractal is a property of self-similarity, each small part of the fractal object is similar to the whole body. The traditional box-counting method (TBCM) to estimate fractal dimension can not reflect the self-similar property of the fractal and leads to two major problems, the border effect and noninteger values of box size. The modified box-counting method (MBCM), proposed in this study, not only eliminate the shortcomings of the TBCM, but also reflects the physical meaning about the self-similar of the fractal. The applications of MBCM shows a good estimation compared with the theoretical ones, which the biggest difference is smaller than 5%.
Authors: A. Al-Hajry, Mohammad Al-Assiri, Stefano Enzo, Kwang Su Na, Neil Cowlam, J. Hefne, L. Jones, Francesco Delogu, H. Brequel
Authors: Zheng Liu, Xiao Mei Liu
Abstract: Microstructural characteristics of A356 alloy prepared by low superheat pouring were researched, and the fractal dimensions of morphology of primary phase in the alloy was calculated. The results indicated that morphology of primary phase in A356 alloy belonged to fractal structure, and the microstructural characteristics in the alloy can be characterized by fractal dimension. There were the different fractal dimensions for the morphology of primary phase prepared by the different process.
Authors: Ai Ping Jiang, Dong Dong Bai, Bo Yu Zhu
Abstract: Combined with the characteristics of forest image, the paper puts forward a new forest fire image segmentation method based on YCBCR and local fractal dimension. First of all, convert the image in RGB color space into YCBCR. Secondly, original triangle prism model algorithm which calculates the square of block matrix is replaced with four pyramid model. This algorithm is easy to be realized, reduce the amount of calculation model, and speed up the image segmentation speed. Segmentation effect significantly is improved, and the simulation experimental results show that this algorithm can be very good for the segmentation image of the flame extracted from complex background. It has obvious, accurate and fast effect and provides a good foundation for the future image analysis and recognition processing.
Authors: Jin Xie, Yu Guan Zhong
Abstract: Fractal dimension is proposed to evaluate grit protrusion feature concerning grit protrusion area and length. The aim is to investigate crystal integrate of diamond grit protruded from grinding wheel after dressing. First, 3D crystal diamond grits are established in AutoCAD concerning various crystal configurations. Second, fractal dimension for original diamond grit is analyzed theoretically. Then, dressing experiment is carried out to investigate fractal dimension of grit protrusion topography by suing image processing of SEM photos of dressed grinding wheel surface. Finally, grit protrusion feature is investigated by fractal dimension concerning the depth of cut in dressing process. It is confirmed that fractal dimension can display grit protrusion feature and it may be used to evaluate dressing performance.
Authors: Rui Qing Qie
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.
Authors: Liang Wen Ji, Mei Li Tsai
Abstract: This paper is based on theoretical methods to study the computer simulation and analysis of the growth of semiconductor thin films. First, according to the traditional theory of thin-film growth, the relationship between the growth morphology and the physical parameters are discussed. Then, fractal theory has been applied to improve the diffusion-limited aggregation (DLA) model. And the simulations of the two-dimensional and three-dimensional thin-film growth are proposed. A computer program of the simulation of the thin-film growth is developed with help of MATLAB. Finally, the results of the simulation of the thin-film growth have been analyzed by the fractal dimension and multifractal spectra. The results of this paper can be applied to the dynamic simulation of nanometer thin-film growth, and an effective simulation tool is to provide the semiconductor process.
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