检索结果-南通市图书馆

Some remarks on the box-counting dimensions

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 1999年第6期 10-16页

作者：丰德军文志英吴军 Department of Applied Mathematics Tsinghua University Beijing 100084 China Center for Advanced Study Department of Applied Mathematics Tsinghua University Beijing 100084 China Department of Mathematics Wuhan University Wuhan 430072 China Department of Mathematics Wuhan University Wuhan 430072 China

Some properties of the upper ami lower box-eounting dimensions and their geometrical explanations are presented. There exists an essential difference between the upper and the lower box-counting dimension. In particul... 详细信息

关键词： box-counting dimension continuity of dimension.

Fractal characterization and frequency properties of near-fault ground motions

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2013年第4期12卷 503-518页

作者： Yang Dixiong Zhang Changgeng Department of Engineering Mechanics State Key Laboratory of Structural Analysis for Industrial EquipmentDalian University of Technology

This study explores the irregularity and complexity of strong earthquake ground motions from the perspective of fractal geometry, and constructs a relation with the frequency content of the ground motions. The box-counting fractal dimensions and five representative period parameters of near-fault ground motions from the Chi-Chi and Northridge earthquakes are calculated and compared. Numerical results indicate that the acceleration and velocity time histories of ground motions present the statistical fractal property, and the dominant pulses of near-fault ground motions have a significant influence on their box dimensions and periods. Further, the average box dimension of near-fault impulsive ground motions is smaller, and their irregular degree of wave forms is lower. Moreover, the box dimensions of ground motions reflect their frequency properties to a large extent, and can be regarded as an alternative indicator to represent their frequency content. Finally, the box dimension D of the acceleration histories shows a considerably negative correlation with the mean period T. Meanwhile, the box dimension of the velocity histories Dye is negatively correlated with the characteristic period T and improved characteristic period Tgi.

关键词： near-fault ground motions fractal property box-counting dimension frequency content indicators correlation analysis

Visualization of collision and aggregation behavior of particles simulating movement of inclusions in molten steel

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2018年第2期25卷 173-180页

作者： Qiang Yue Zeng Hu Zhao-yang Wu Hong-ming Long Qing-min Meng Key Laboratory of Metallurgical Emission Reductionand Resources Recycling (Anhui University of Technology) Ministry of Education Ma'anshan 243002 Anhui China The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081 Hubei China School of Metallurgical Engineering Anhui Universityof Technology Ma'anshan 243002 Anhui China

Inclusions with sizes less than 1 μm in molten steel are difficult to float up to the molten steel and slag interface owing to their slow terminal velocity. Thus, increasing the size of inclusion is essential for accelerating the removal of inclusions. Polystyrene particles simulating inclusions in molten steel were quantified by direct observation of the particle collision behavior in a turbulent flow in a water model. The box-counting fractal dimension of particles was calculated by processing the binary images of aggregated particles. The fractal dimension of the outer contours of the single plastic particles was smaller than that of the aggregated particles. The fractal dimension was varied from 1.14 to 1.35. When two or more monomer particles collide, the aggregates are separated more easily, as the temperature increases from 40 to 80 ℃. The aggregated particles were loose and easy to separate in the high-temperature aqueous solution. The effect of temperature on the surface tension of liquid and the interracial tension of solid and liquid is obvious. The particles are wetting in the water solution at a temperature more than 60 ℃. The relationship between the velocity of the particles and the fractal dimension of the solid particles with the equivalent diameter was discussed.

关键词： Non-metallic inclusion Fractal box-counting dimension Visualization Collision. Aggregation

THE REGULARITY OF RANDOM GRAPH DIRECTED SELF-SIMILAR SETS

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mathematica Scientia 2004年第3期24卷 485-492页

作者： ZhangXiaoqun LiuYanyan DepartmentofMathematics WuhanUniversityWuhan430072China

A set in Rd is called regular if its Hausdorff dimension coincides with its upper box counting dimension. It is proved that a random graph-directed self-similar set is regular a.e..

关键词： Random graph-directed self-similar set Hausdorff dimension box-counting dimension regular

Fractals in Spatial Patterns of Vegetation Formations

在线全文

学校读者我要写书评

暂无评论

Tsinghua Science and Technology 2006年第4期11卷 462-469页

作者：宋志远黄大明 Masae Shiyomi 王昱生 Shigeo Takahashi Hori Yoshimichi Yasuo Yamamuru 陈俊 Institute of Ecology Department of Biological Sciences and Biotechnology Tsinghua University Beijing 100084 China Faculty of Science Ibaraki University Bunkyo 2-1-1 Mito 310-8512 Japan Grassland Research Station College of Animal Science Northeast Agricultural University Harbin 150030 China National Institute of Livestock and Grassland Science 768 Senbonmatsu Nishinasuno Tochigi 329-2793 Japan

The spatial distribution patterns of species are always scale-dependent and spatially self-similar in ecological systems. In this work, vegetation distribution data collected from the vegetation map of the Xigaze region was analyzed using a box-counting method. The power law of the box-counting dimension （DB） across a range of scales （5-160 km） confirms the fractal patterns for most vegetation formations, while the fluctuations of the scale-specific DB among the different abundance groups indicate limitations of fractal coherence. The fractal method is shown to be a useful tool for measuring the distribution patterns of vegetation formations across scales, which provides important information for both species and habitat conservation, especially in landscape management.

关键词： area of occupancy box-counting dimension fractal scale vegetation formation

Fractal analysis of thermal conduction of loose coal

在线全文

学校读者我要写书评

暂无评论

Mining Science and Technology 2010年第6期20卷 831-834,838页

作者： WANG Yijiang ZHOU Guoqing WEI Yazhi ZHOU Yang School of Mechanics & Civil Engineering China University of Mining & Technology Xuzhou 221116 China State Key Laboratory of Geomechanics & Deep Underground Engineering China University of Mining & Technology Xuzhou 221008 China

For deep mining engineering, heat transfer of coal mass is a vital factor in the thermal environment of coal mines. In order to study the thermal conduction mechanism, we obtained gray images of coal mass microstructure by scanning samples with a digital microscope. With the use of Matlab, these gray images were transformed into binary images, which were then transformed into a corresponding matrix consisting only of the values 0 and 1. According to the calculation method of box-counting dimension, we calculated the fractal dimension of the loose coal to be approximately 1.86. The thermal conductivity expressions of loose coal were derived based on the simulation method of thermal resistance. We calculated the thermal conductivity of loose coal by using a fractal model and compared the calculated values with our experimental data. The results show that the test data show an encourag-ing agreement with the calculated values. Hence fractal theory is a feasible method for studying thermal conductivity of loose coal.

关键词： loose coal thermal conductivity fractal theory box-counting dimension

Fractal Studies on Primary Phase Morphology of TA15 Titanium Alloy after Hot Compressive Deformation

在线全文

学校读者我要写书评

暂无评论

Journal of Shanghai Jiaotong university(Science) 2011年第3期16卷 343-346页

作者：杨夏炜朱景川来忠红刘勇占家军 School of Materials Science and Engineering Harbin Institute of Technology

The goal of this study is to establish relationships between the hot compression deformation behaviors and the fractal dimension of primary phase morphology of TA15 titanium alloy using the analytical methods of metallurgical microscope and transmission electron microscope coupled with box-counting dimension method. The hot compression deformation behaviors vary with decreasing fractal dimension owing to the change of microstructure caused by different parameters of the hot compressive *** results indicate that TA15 alloy shows dynamic recrystallization characteristics at deformation temperature lower than 850℃while fractal dimension exhibits a moderate decreasing trend with the temperature increasing,and shows dynamic recovery characteristics at deformation temperature higher than 850℃while fractal dimension reduces rapidly with the temperature *** fractal dimension displays non-linear relationship with fraction of primary phase and with aspect ratio of primary phase.

关键词： compression deformation behaviors fractal dimension TA15 alloy box-counting dimension