共查询到19条相似文献,搜索用时 78 毫秒
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分形概念及其在材料科学中的应用 总被引:1,自引:0,他引:1
本文首先结合几个数学构造分形的例子介绍分形概念,然后对分形在材料科学中的应用作了简要介绍,主要包括:粉体生长中的分形、断裂面的分形、离子注入等非平衡方法产生的分形、表面分形、无机材料中的分形、自旋玻璃中的分形. 相似文献
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透射电镜研究表明,4,40-双硬脂酰胺基二苯醚在水中聚集、自组装成缠绕细纤维状聚集体,进而使整个体系形成三维网络结构.水分子被包囊在这个网络结构中,形成一种新型的凝聚体系(水分子凝胶).水分子凝胶是一种典型的纳米介孔物质,其复杂的微孔结构可以用分形维数D来表征,通过气体吸附方法(孔度法和比表面积法)计算,求得水分子凝胶体系的微孔结构的分形维数为2.1?2.2.对于纤维状三维网络结构的分形表征,通过粘度法和Cayley分形树模型得出分形维数为1.98.由此推测其分形网络形成的过程是一个初始成核-生长-枝化的循环过程. 相似文献
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利用分形图形具有无限可分和比例尺度上的自相似的特征以及可以产生无限变量重复码的特点,通过计算机控制激光双光束干涉光刻成点阵全息光栅,从而形成数字像素全息图.构造出分形图形的迭代函数系统框架,形成丰富多彩,变化多端的分形图形,以此对点阵全息光栅编码,光刻成分形数字像素全息图. 相似文献
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The fractal and multi-fractal patterns of metal atoms are observed in the surface layer and cross section of a metal ion implanted polymer using TEM and SEM for the first time. The surface structure in the metal ion implanted polyethylene terephthalane (PET) is the random fractal. Certain average quantities of the random geometric patterns contain self-similarity. Some growth origins appeared in the fractal pattern which has a dimension of 1.67. The network structure of the fractal patterns is formed in cross section, having a fractal dimension of 1.87. So it can be seen that the fractal pattern is three-dimensional space fractal. We also find the collision cascade fractal in the cross section of implanted nylon, which is similar to the collision cascade pattern in transverse view calculated by the TRIM computer program. Finally, the mechanism for the formation and growth of the fractal patterns during ion implantation is discussed. 相似文献
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Experimental study is performed of optical diffractions by two-dimensional, self-similar mass and surface fractal apertures as well as mass fractal apertures bounded by surface fractals. Self-similar intensity distributions are observed in the Fraunhofer diffraction fields from surface and mass fractal apertures. Power law decays in average intensities of the diffraction patterns are also investigated for the mass, surface and combined fractal apertures in connection with the fractal dimensions of the objects. 相似文献
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FENG Shaotong HAN Dianrong & DING Heping Department of Physics Nanjing Normal University Nanjing China 《中国科学G辑(英文版)》2004,47(4):485-491
The extension of ordinary Fourier transform to the fractional Fourier transform (FRFT) was first accomplished by Namias in 1980. He gave a complete mathematical definition and discussed the eigenfunction of the transform. Using a system of lenses Lohmann et al.[1] first successfully realized the FRFT optically and designed the single lens mode and double lens mode for the realization of the FRFT of continuously variable fractional order. The concept of fractals was first proposed by Man… 相似文献
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With the aid of an improved projective approach and a linear variable separation method,new types of variable separation solutions (including solitary wave solutions,periodic wave solutions,and rational function solutions)with arbitrary functions for (2 1)-dimensional Korteweg-de Vries system are derived.Usually,in terms of solitary wave solutions and rational function solutions,one can find some important localized excitations.However,based on the derived periodic wave solution in this paper,we find that some novel and significant localized coherent excitations such as dromions,peakons,stochastic fractal patterns,regular fractal patterns,chaotic line soliton patterns as well as chaotic patterns exist in the KdV system as considering appropriate boundary conditions and/or initial qualifications. 相似文献
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分形介质的传热与传质分析(综述) 总被引:9,自引:0,他引:9
本文论述了分形介质的分形理论和数学基础,并简要综述了用分形理论和方法研究分形介质的传热与传质特性(如多孔介质的渗透率、热导率以及池核态沸腾换热)方面目前所取得的研究进展,最后扼要展望了用分形理论和方法进一步研究分形介质的传热与传质的可能的若干课题和方向。 相似文献
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MA Zheng-Yi ZHU jia-Min ZHENG Chun-Long 《理论物理通讯》2004,42(10)
A novel phenomenon that the localized coherent structures of a (2 1)-dimensional physical model possess fractal behaviors is revealed. To clarify the interesting phenomenon, we take the (2 1)-dimensional Boiti-Leon Pempinelli system as a concrete example. Starting from an extended homogeneous balance approach, a general solution of the system is derived. From which some special localized excitations with fractal behaviors are obtained by introducing some types of lower-dimensional fractal patterns. 相似文献
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MAZheng-Yi ZHUJia-Min ZHENGChun-Long 《理论物理通讯》2004,42(4):521-523
A novel phenomenon that the localized coherent structures of a (2 1)-dimensional physical model possess fractal behaviors is revealed. To clarify the interesting phenomenon, we take the (2 1)-dimensional Boiti Leon-Pempinelli system as a concrete example. Starting from an extended homogeneous balance approach, a general solution of the system is derived. From which some special localized excitations with fractal behaviors are obtained by introducin gsome types of lower-dimensional fractal patterns. 相似文献