基于可变步长的光谱响应曲线分形维计算方法研究

提出了一种基于可变步长(即基于不同采样率)的高光谱图像响应曲线分形维计算方法。该方法在不同的采样率下对光谱响应曲线进行采样,计算相邻点的光谱响应差值,统计采样点的差值总和,利用最小二乘法求出分形维。为了提高计算效率,运用多线程的技术将高光谱图像分成几个部分,各部分的分形维由多核计算机同时并行计算。实验结果表明,该方法能较好地改善量规法与网格法计算效率低、精度不高等问题,取得了良好的效果。

基于加权小波分形的卫星遥感图像飞机类型识别

针对卫星遥感图像中飞机目标的特点,提出一种基于加权小波分形的识别算法。首先利用小波对图像的“显微”能力和“极化”能力,提取子波段显著特征;然后应用分形理论对其进行分析降维,由分形维构成特征向量;并根据各子波段的不同描述能力,对分形维向量进行加权处理;用最小距离分类器识别分类。实验结果表明:该算法能够兼顾目标的整体信息和局部细节,与Hu不变矩、Zernike矩、Fourier描述子相比,识别率高。

非线性机械设备系统的分形神经网络诊断方法

从分形原理出发 ,提出了非线性机械设备系统信号的分形计算维数的概念。将分形计算维数概念与多层感知器神经网络结合 ,建立了机械设备的分形神经网络诊断方法。通过对滚动轴承系统实例诊断获得了较为准确的模式识别的结果。

分形模糊神经网络诊断方法研究和应用

从分形理论和神经网络原理出发 ,基于信号分形计算维数定义 ,以采样周期和分形计算维数两个坐标对信号特征进行合理地模糊化处理 ,提出分形维数隶属度特征量概念·以多时间尺度采样所获得的分形维数隶属度作为网络输入 ,单位矩阵为网络输出的分形模糊神经网络 ,建立了时域精确诊断新方法 ,通过对典型齿轮系统故障进行精确诊断 ,结果表明分形模糊神经网络诊断方法的有效性·

基于Matlab程序对干湿状态下沥青路面磨损情况的定性定量分析研究

基于福州滨海新区施工建设的沥青路面工程,在通车使用过程中发现路表面出现磨损松散病害,一定程度上影响了交通行车安全性和路面的服役寿命。因此,对福州滨海新城10条沥青路面进行磨损调查,观测沥青路面在干湿状态下的磨损情况,并采用Matlab程序对干湿状态下的磨损图像进行二值化处理和分形维数计算,通过统一的标准定性定量分析沥青路面的磨损情况。

快速高准确度云检测算法及其应用

采用光谱阈值判别和纹理分析相结合的方法,提出一种基于树状判别结构的快速高准确度云检测算法,综合利用多个判别准则,确定图像中云层覆盖情况,与传统方法相比能够获得更高的分辨精确度。树状判别结构还能够在平均意义上显著提高算法运行效率。同时,提出了一种改进的分形维数计算方法,能够在不影响精确度的前提下,使算法的运行效率提高5倍左右,基本满足实时性的要求。所提出的云检测算法已在中巴地球资源卫星项目中实际应用,实际测试结果表明,该算法达到自动云检测的虚警概率小于5%,漏警概率小于10%的工程要求。

Morphology characteristics of joint surface in rock mass

In order to quantify the characteristics of the surface of jointed rock mass,new equipment,the three-dimensional laser surface topography instrument,was used to accurately measure surface morphology of joints.Scan pictures and parameters were obtained to describe the rock joint surface characteristics,for example,the height frequency of surface,and mean square roughness.Using the method of fractal dimension,the values of joint roughness coefficient(JRC) were calculated based on the above parameters.It could access to the joint surface rock sample morphology of the main parameters of characteristic.The maximum peak height is 2.692 mm in the test joint plane.The maximum profile height is 4.408 mm.JRC value is 6.38 by fractal dimension computing.It belongs to the smooth joint surface.The results show that it is a kind of the effective method to quantitatively evaluate the surface topography by the three-dimensional laser surface topography instrument and the fractal dimension method.According to the results,during the process of underground large-scale mining,safe measures to prevent slip failure of the joint plane by controlling surface tension and shear mechanical response were proposed.

分形定量选择遥感影像最佳空间分辨率的方法与实验

遥感影像观测尺度是遥感信息提取研究的重要内容之一,也是遥感信息提取的焦点。以往,遥感影像尺度特征的分析大多基于地统计学,其主要体现遥感影像中的线性特征,而实质上遥感影像中既存在线性特征,又存在非线性特征。因此,在深入剖析遥感影像尺度效应及分形特征机理的基础上,本文探讨了分形理论定量选择遥感影像最佳空间分辨率(也称最佳像元观测尺度)的方法。以IKONOS全色影像的建筑用地、耕地、林地为研究对象,分别使用FBM、DBM、TPM 3种分形维数计算模型,实现了3种地物在不同空间分辨率下分形维数的计算。实验结果表明,每种地物的分形维数是随空间分辨率的增大,总体呈下降趋势,且在某些特征空间分辨率上会出现拐点。从遥感影像尺度效应分析可知,遥感影像空间格局随尺度的不同,其内部结构也不同。且随着尺度的增大,很多细节将会被忽略,影像的粗糙度也随着降低。而分形维数是目前为止描述对象自相似性和不规则度的唯一基本量化值,其直观上与物体表面的粗糙程度相吻合。因此,这些拐点对应的分形维数对地物的最佳空间分辨率的选择具有一定指示意义。通过本文研究可知,使用分形理论方法研究遥感影像最佳空间分辨率(或最佳像元观测尺度),打破以往观测尺度方法研究范畴,从不同角度去分析遥感影像观测尺度问题对GIS研究与地学应用具有一定的理论和指导意义。

Realizing the Box-counting Method for Calculating Fractal Dimension of Urban Form Based on Remote Sensing Image

In the research of fractal cities, the fractal dimension is very important. It is used to describe the fractal character of the city. The authors have designed two approaches to calculate the fractal dimension by the box-counting method through an example of Beijing, which are called the vector method and the grid method, respectively. The former calculates the fractal dimension through an intersecting analysis in ArcView; and the latter is carried out by programming in Matlab. They are compared from three aspects： the calculating process, the limits in use, and the results. As a result, the conclusion is made that there are merits and faults on both methods, and they should be chosen to use properly in practical situation.

Fractal characteristics of far-field diffraction patterns for two-dimensional Thue-Morse quasicrystals

We report a numerical method to analyze the fractal characteristics of far-field diffraction patterns for two-dimensional Thue-Morse (2-D TM) structures. The far-field diffraction patterns of the 2-D TM structures can be obtained by the numerical method, and they have a good agreement with the experimental ones. The analysis shows that the fractal characteristics of far-field diffraction patterns for the 2-D TM structures are determined by the inflation rule, which have potential applications in the design of optical diffraction devices.