Total and selective reuse of Krylov subspaces for the resolution of sequences of nonlinear structural problems

This paper deals with the definition and optimization of augmentation spaces for faster convergence of the conjugate gradient method in the resolution of sequences of linear systems. Using advanced convergence results from the literature, we present a procedure on the basis of a selection of relevant approximations of the eigenspaces for extracting, selecting and reusing information from the Krylov subspaces generated by previous solutions in order to accelerate the current iteration. Assessments of the method are proposed in the cases of both linear and nonlinear structural problems. Copyright © 2012 John Wiley & Sons, Ltd.     

基于多分辨率阈值的非均匀光照微视觉图像实时分割技术研究

为了满足微纳和生物医学领域对微视觉图像目标信息高精度实时提取的需求,提出一种基于多分辨率阈值的非均匀光照微视觉图像实时分割技术.针对传统方法所存在的在非均匀光照微视觉图像分割过程中难以精确估计阈值和实时性差等问题,首先根据微视觉图像的梯度概率密度稀疏分布特性,建立灰度强度分布估计目标函数,并利用迭代加权最小二乘法实现灰...     

结构损伤识别中小波基函数的选择

基于小波变换损伤指标不仅可以反映试件不同加载阶段的损伤程度,还可以为判断结构何时屈服提供一定的依据。小波基函数的选用是该损伤指标应用的一大难点。通过枚举法挑选合适的小波基函数及分解层数,并用此对两种不同边缘约束措施的叠合板式剪力墙和两种普通剪力墙进行了分析,计算结果与试验结果吻合良好,表明该方法是可靠的。     

多分辨率压缩感知技术软件仿真与分析

压缩感知理论(Compressed Sensing,CS)为宽带信号的直接信息采样(Analog-to-Information,A-to-I)提供了解决方法。针对现有的CS压缩算法没有充分考虑信息的重要性差异,运用仿真手段验证了多分辨率压缩感知(Multiresolution CS,MCS)思想的正确性,仿真结果表明:MCS能够动态地保护信号中蕴含的重要信息,且与单一分辨率CS重构算法比较,精度明显提高。为下一步将MCS为直接信息采样提供软件支持。     

非整点扩展矩阵FMRA小波的存在性

对于一类非整点矩阵A,通过构造最小频率支撑框架小波的方法,证明了存在一类非整点框架多分辨率分析小波。     

小波域声呐图像自适应增强

声呐图像受噪声污染严重、对比度低,给后期的定位识别带来不便,而传统的处理方法容易造成边缘模糊.针对这一问题,提出了一种图像自适应增强算法.该算法利用形态小波对声呐图像进行自适应的多分辨率分析,分别增强不同尺度上的信号或细节,通过多通道重构图像的加权实现去噪和对比度提高.仿真结果表明该算法快速有效,对高斯噪声和冲击性噪声都具有较好的鲁棒性,处理后的声呐图像边缘细节信息保留完好,得到了理想的增强效果.     

用VSP资料实现声测井与地面地震资料的匹配

在分析声测井与地面地震资料的差异以及回顾多分辨率分析理论的基础上，试验了在ＶＳＰ资料的约束下，用多分辨率分析方法改善声测井与地面地震资料的匹配问题，理论模型和野外实测数据表明，ＶＳＰ资料提供的直接深时关系是实现声测井与地面地震资料正确标定的宝贵资料；多分辨率分析方法与直接抽取、多眯平均及中值滤波等方法相比，能使声测井与地震资料得到更好地匹配。     

A new approach for flicker analysis using information‐theory‐based wavelet energy entropy

Flicker is one of the critical power quality disturbances seen in power distribution networks nowadays. Besides its effects on the human life, it causes malfunctioning and misoperation of sensitive electrical equipment. The measurement of the flicker level is defined in IEC 61000‐4‐15 standard by a flicker meter, which deals only with voltage signals and is not sufficient to understand the contribution of the load and background power systems separately. Therefore, in this letter we present a new approach to the evaluation of flicker characteristics in the light of multiresolution wavelet analysis and information‐theory‐based wavelet energy entropy analysis together. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Long-range Dependence: Revisiting Aggregation with Wavelets

The aggregation procedure is a natural way to analyse signals which exhibit long-range-dependent features and has been used as a basis for estimation of the Hurst parameter, H . In this paper it is shown how aggregation can be naturally rephrased within the wavelet transform framework, being directly related to approximations of the signal in the sense of a Haar multiresolution analysis. A natural wavelet-based generalization to traditional aggregation is then proposed: 'a-aggregation'. It is shown that a-aggregation cannot lead to good estimators of H , and so a new kind of aggregation, 'd-aggregation', is defined, which is related to the details rather than the approximations of a multiresolution analysis. An estimator of H based on d-aggregation has excellent statistical and computational properties, whilst preserving the spirit of aggregation. The estimator is applied to telecommunications network data.     

Multiresolution for Algebraic Curves and Surfaces using Wavelets

This paper describes a multiresolution method for implicit curves and surfaces. The method is based on wavelets, and is able to simplify the topology. The implicit curves and surfaces are defined as the zero-valued piece-wise algebraic isosurface of a tensor-product uniform cubic B-spline. A wavelet multiresolution method that deals with uniform cubic B-splines on bounded domains is proposed. In order to handle arbitrary domains the proposed algorithm dynamically adds appropriate control points and deletes them in the synthesis phase.