一种基于小波域的分形编码预测方法

提出了一种小波域内相邻子图的分形编码预测方法.首先选择合适小波基对图像进行二级分解,然后对三个二级高频子图进行Jacqain方法的分形编码,利用小波域内同方向不同分辨率子图之间的相似性,对得到的分形编码参数进行适当比例变换,最终从水平、垂直和斜方向等三个方向近似预测出对应的一级高频子图分形编码.实验表明,与Jacqain相比本方法在同类图像基本保证解压图像质量的同时,极大地缩短了编码时间和提高了压缩比.     

近红外图像消噪方法的对比实验研究

为了选择一种既能消除近红外图像噪声又能达到保持其图像边缘要求的消噪方法,通过比较各种常见的图像去噪算法,采用信噪比(SNR)、均方根误差(RMSE)和图像灰度曲面图等作为图像去噪效果的评估.对实际拍摄的多幅近红外图像进行消噪效果对比,仿真实验结果表明:在综合考滤图像去噪平滑效果、图像清晰程度和时间复杂度的基础上,分形消噪法较优,可应用于近红外图像的消噪处理.     

有耗分形粗糙面电磁散射的相位微扰法

本文采用Weierstrass－Mandelbrot分形函数描述粗糙表面,根据粗糙面的电磁散射理论,利用相位微抗法推导出有耗分形粗糙介质表面电磁散射系数的理论计算公式。     

海面电磁散射回波的分形特性

本文引入时变分形Weistrass—Mandelbrot函数描述海面的局部动态特征，采用Kirchhoff解近似分析电磁散射场的时域分形特性，导出了海面电磁散射系数的分形模型。理论分析和试验结果表明，海面的散射回波信号保留了海面的一些分形特征，散射系数属于分形函数，其盒维数与海面的分形维数近似相等。     

基于分级匹配和分形插值的图像压缩编码

本文在分形方块图像编码的基础上,提出一种分级匹配分形编码和分形插值相结合的图像压缩方法,实验结果表明,在基本保持重建图像质量的前提下,编码时间大为缩短。     

基于IFS分形理论的信源编码技术的研究

本文首次系统地研究了基于ＩＦＳ分形理论的信源压缩编码与传统方法的关系。     

含噪声混沌信号的小波去噪方法研究

基于混沌信号具有分形结构的特点，提出了一种分数维与小波变换相结合的带观测噪声混沌信号的噪声去除新方法，利用噪声小波变换特性提取信号的真实分数维，进而根据欲处理混沌时间序列分数维与信号真实分数维之差控制小波包除噪的阈值及位置，达到噪声与信号的自适应分离。该方法克服了以往对未知动力系统方程信号除噪的盲目性，仿真结果表明此法有效可行。     

Microstructure–function relationships of heat-induced gels of porcine haemoglobin

The purpose of this work was to use image analysis to study the microstructural properties of haemoglobin gels, with structural changes induced by pH conditions, and their correlations with physical properties such as texture and water holding capacity (WHC). Two types of networks showing great differences in the dimensions of the gel structure were obtained as influenced by pH. At pH < 5.5 there was a shift from an aggregated to a fine-stranded gel type. Fractal dimension values revealed that more complex structures corresponded to softest and non-exudative gels. Lacunarity and pore size, which were used to study the pore distribution within the network, confirmed that softest gels with high WHC showed large number of small cavities. Finally, correlations between textural attributes, i.e. springiness and adhesiveness, and spatial variability, referred quantitatively to the degree of compactness, were also established.     

On the fractal characteristics of low Damköhler number flames

Knowledge of the fractal properties of premixed flame surfaces can potentially be used to help develop turbulent combustion models. Here, direct numerical simulations of low Damköhler number flames are used to analyse the fractal nature of the flames. Two sets of data are considered: (i) thermochemical hydrogen–air turbulent premixed plane-jet flames with detailed chemistry and (ii) thermonuclear flames in type Ia supernovae. A three-dimensional box counting method is used to investigate fractal dimension of the flame surface, characterising the self similarity of flame fronts. In the premixed flames, the fractal dimension is found to vary in time between 2.1 and 2.7. The supernovae flames in distributed combustion regimes yield fractal dimension about 2.7. The results for the maximum fractal dimensions are higher than previously reported. They are explained theoretically by a Reynolds number similarity argument which posits that the high Reynolds number, low Damköhler number limiting value of the fractal dimension is 8/3. Also tested is Mandelbrot’s fractal additive law which relates the fractal dimension determined in two dimensions, which is typical of experimental measurements, to that in three dimensions. The comparison of the fractal dimension in both two-dimensional and three-dimensional spaces supports the additive law, even though the flames considered do not formally satisfy isotropy. Finally, the inner-cut off is extracted from the hydrogen flames and found to be consistent in order of magnitude with Kolmogorov scaling.