Extended stochastic gradient identification algorithms for Hammerstein–Wiener ARMAX systems

An extended stochastic gradient algorithm is developed to estimate the parameters of Hammerstein–Wiener ARMAX models. The basic idea is to replace the unmeasurable noise terms in the information vector of the pseudo-linear regression identification model with the corresponding noise estimates which are computed by the obtained parameter estimates. The obtained parameter estimates of the identification model include the product terms of the parameters of the original systems. Two methods of separating the parameter estimates of the original parameters from the product terms are discussed: the average method and the singular value decomposition method. To improve the identification accuracy, an extended stochastic gradient algorithm with a forgetting factor is presented. The simulation results indicate that the parameter estimation errors become small by introducing the forgetting factor.     

Classification of Fuzzy Mathematical Morphologies Based on Concepts of Inclusion Measure and Duality

Mathematical morphology was originally conceived as a set theoretic approach for the processing of binary images. Extensions of classical binary morphology to gray-scale morphology include approaches based on fuzzy set theory. This paper discusses and compares several well-known and new approaches towards gray-scale and fuzzy mathematical morphology. We show in particular that a certain approach to fuzzy mathematical morphology ultimately depends on the choice of a fuzzy inclusion measure and on a notion of duality. This fact gives rise to a clearly defined scheme for classifying fuzzy mathematical morphologies. The umbra and the level set approach, an extension of the threshold approach to gray-scale mathematical morphology, can also be embedded in this scheme since they can be identified with certain fuzzy approaches.

遥感图像分形特征提取与分割

分形理论由B.B.Mandelbrot于20世纪70年代中期创立,现已被广泛地应用于自然科学和社会科学的几乎所有领域.本文在前人研究的基础上,利用双毯法(Double Blanket Method)提取出图像的分形特征并用于图像分割,进一步证实了分形在此领域的可行性和有效性.首先,通过比较局部分形维数偏移全局分形维数的标准差来确定适合该方法的最优滑动窗口.其次,考虑到单尺度分维特征的局限性,提取出多尺度的特征值并建立分形维数谱.然后,以模拟图像为例,分析图像中各区域的分维谱,选择适当尺度的分形特征,利用最大似然法对图像进行分割.最后,将分形理论应用于遥感图像中,与传统的基于灰度值特征的图像分割方法相比,加入图像的空间分形纹理特征后分割精度明显提高.研究结果表明:分维值的大小和变化趋势可以表示不同地物的空间复杂度,结合地物的光谱以及灰度信息能有效地识别目标地物.     

基于多尺度空间边缘检测的研究

边缘检测一直是计算机视觉和图像处理领域的经典研究课题之一。该文综述了多尺度边缘检测技术;介绍了多尺度检测的基本概念;归纳了现有的各种多尺度形态学边缘检测方法。     

基于工作站机群并行求解有限元线性方程组

随着计算机高速网络技术的发展,工作站机群正在成为并行计算的主要平台.有限元线性方程组在土木工程结构分析中是最常见的问题.预处理共轭梯度法(PCGM)是求解线性方程组的迭代方法.对预处理共轭梯度法进行并行化并在两个不同的机群上实现,对存储方式进行详细分析,编程中采用了稀疏矩阵向量相乘的优化技术.数值结果表明,设计的并行算法具有良好的加速比和并行效率,说明并行计算能更快地求解大规模问题.     

嵌入式GPS／GIS系统设计的几个关键问题及解决方法

提出嵌入式GPS/GIS系统设计中的几个关键技术问题并给出解决方案。对GPS数据质量采用神经元辨识的方法进行控制;对大数据量底图数据采用一种新的地图综合方法建立多级显示机制,节省内存,提高图形显示效率;建立基于la-bel的空间算子实现方式,完成采集图斑的现场变更,减少内业数据处理的工作量。实际应用表明,这些方法能够满足嵌入式GPS/GIS系统应用于土地调查业务的需要,提高了调查效率。     

液剂视频序列中运动异物的模糊自适应分割

运动异物的正确分割是实现液剂自动检测的关键.提出一种基于帧差图空间方差和方差梯度的液剂异物模糊自适应阈值分割算法.首先将4帧序列图像差分得到的2幅帧差图分为5×5的图像块,计算2幅帧差图对应图像块间的方差和方差梯度,并以两者的乘积构成新特征图;然后使用自适应阈值对新特征图进行运动异物分割和提取.为使阈值能够跟随图像块灰度变化,阈值的调整采用模糊推理依据方差和方差梯度变化自适应实现.实验及实际测试结果表明,该算法能够满足低对比度和局部光照变化的液剂异物实时检测要求,是一种实用有效的图像分割算法.     

基于二重差分法的光流场运动检测

对视频图像序列中运动目标的检测,是计算机视觉领域长期关注的问题.传统的Horn-Schunck光流算法非常耗时,不利于在视频图像序列中做实时分析,故提出采用结合背景差分法与帧间差分法的二重差分法(DS)来做光流算法的预处理.实验结果也表明二重差分法的光流算法(DSOF)比单纯用Horn-Schunck方法计算光流效率更高,用时更短,能更好地满足对视频图像序列做实时运动检测分析的需求.     

一种基于鲁棒Hausdorff距离的目标匹配算法

在传统的基于边缘位置的Hausdorff距离匹配的基础上,将边缘的梯度信息引入到距离度量当中,构造了一种新的三维距离函数。在此基础上,提出了一种鲁棒的三维Hausdorff距离及其目标匹配算法,采用粗匹配与精匹配相结合的两步匹配策略有效解决了由距离度量维数增加所导致的算法复杂性增大的问题。实验表明,该算法相对于传统的基于边缘位置的Hausdorff距离目标匹配算法在鲁棒性上有很大的提高。     

Pixel level image fusion scheme based on accumulated gradient and PCA transform

A new image fusion scheme based on local accumulated gradient and PCA transform is presented. The image fusion process begins by taking the Dual tree complex wavelet transform of the source images. Then, the fused local detailed coefficients are chosen according to local accumulated gradient rule, and the fused approximate coefficients are acquired by selection or averaging rule based on PCA. Finally, the fused image can be obtained by taking the inverse dual tree complex wavelet transform of the fused composite coefficients. The experimental results show that the proposed method is an efficient approach to image fusion.