Optimal allocation in stratified sampling with partial information

Summary The classical allocation formula of Neyman is replaced by a new formula which can accommodate prior information on the ratio of means in two strata. To accomplish this, a Bayesian approach is adopted and in this context partial prior information is quantified over the spectrum from absolute certainty to completely unknown.     

A learning-based method for compressive image recovery

Compressive sensing (CS) theory dictates that a sparse signal can be reconstructed from a few random measurements. An important issue of compressive image recovery (CIR) is that the optimal sparse space is usually unknown and/or it often varies spatially for non-stationary signals (e.g., natural images). In this paper, apart from fixed sparse spaces, prior models, specifically a set of piecewise autoregressive (AR) models that encode the common statistics of image micro-structures, are learned from example image patches, and they are then used to construct adaptive sparsity regularizers for CIR. Furthermore, a complementary non-local structural sparsity regularizer is also incorporated into the CIR process to improve the robustness. The regularization by local AR model and non-local redundancy makes the proposed CIR very effective. Experimental results on benchmark images validate that the proposed algorithm can outperform significantly previous CIR methods in terms of both PSNR and visual quality.     

Effects of Prior Corrosion with and Without Stress on the Mechanical Properties of 7475-T761 Aluminum Alloy

The effect of prior corrosion on the mechanical properties of 7475-T761 aluminum alloy was investigated by immersion test, stress corrosion test, cathode charge method and electrochemical polarization test. Results show that prior corrosion in the solution with 3 wt% Na Cl and 0.5 wt% H2O2 leads to mechanical properties deterioration of 7475-T761 aluminum alloy. Moreover, the elongation decreases significantly. This is mainly attributed to electrochemical corrosion and hydrogen embrittlement, in which corrosion plays a major role. Tensile stress promotes the degradation of the mechanical properties by accelerating the pitting corrosion and hydrogen embrittlement.     

空间预警系统的关机点时间估计及精度分析

在空间预警系统中,由于系统采用红外测量,数据采样率低,很难直接获得关机点的高精度观测值.分别针对单星和多星预警系统,在已知先验信息的条件下,首先基于一次具体的测量,给出了合理的关机点时间的估计方法,分析和计算了参数估计的误差分布函数和估计精度;然后在不考虑具体测量情况下,得到了整个预警系统的关机点时间估计精度的量化表达式.这有助于深入了解关机点时间参数估计的特性,也为落点的精度估计提供了依据.     

一种基于分类的融合算法

提出了一种基于分类的融合算法 ,可用于融合低分辨率多光谱影像和配准的高分辨率全色波段影像 .算法的主要步骤如下 :(1)将 1m高分辨率全色波段影像和 4 m低分辨率多光谱影像进行几何配准 ;(2 )采用监督或非监督分类算法对高分辨率影像和配准的多光谱影像进行统一分类 ;(3)根据每一类所对应的高分辨率全色波段影像直方图和相应的空间关系 ,对配准后单个波段的多光谱影像进行调整 .(4)采用柱状坐标系对调整后的多谱影像进行 HIS(Hue,Intensity,Saturation)变换 ,并反变换至 RGB(red,green,blue)彩色空间 ,从而得到融合影像 .以天安门附近 10 0× 10 0大小 IKONOS的 1m高分辨率全色波段影像和 4 m多光谱影像为例 ,对融合算法进行了验证 .实验结果表明 :(1)此算法可以融合分类信息、全色波段的高分辨率信息和多光谱波段的光谱信息 ,突出分类信息作为先验知识的重要性 [1 ] ;(2 )在精确分类的基础上 ,可部分消除目标物边界的假彩色现象 ,有较好的目视判读效果 ;(3)对融合过程中 ,先验知识与空间关系的加入作了一些有益的尝试 .     

Estimation of weibull reliability from few life tests

The 2–parameter Weibull model can be re–parameterized in terms of shape parameter and a prefixed age for which a reliability estimation is required. Using the uniform and beta priors, some new point and lower bound reliability estimators were derived. These estimators appear to be very suitable to meet the needs of fast and cheap reliability evaluation during production. Their characteristics were studied by means of a Monte Carlo simulation and were compared with those of the maximum likelihood estimators.     

综合单元验前信息的系统可靠度Bayes评估

针对目前可靠性评估方法的不足，提出了综合单元验前信息的系统可靠度Bayes评估方法。该方法根据验前信息确定各单元的验前分布，将寿命型单元等效为成败型单元，将混联系统等效为串联系统，从而将复杂系统转化为成败型单元串联系统，在此基础上利用各单元的验后前两阶矩进行系统可靠度综合，能够较好地解决传统方法对数据依赖性过强、不能有效综合验前信息等缺陷。最后通过仿真示例验证了该方法的合理性与有效性。     

An Improved FoE Model for Image Deblurring

Image restoration from noisy and blurred image is one of the important tasks in image processing and computer vision systems. In this paper, an improved Fields of Experts model for deconvolution of isotropic Gaussian blur is developed, where edges are preserved in deconvolution by introducing local prior information. The edges with different local background in a blur image are retained since local prior information is adaptively estimated. Experiments indicate that the proposed approach is capable of producing highly accurate solutions and preserving more edge and object boundaries than many other algorithms.     

改进学习贝叶斯网络结构的MDL准则

文章针对用于BN结构学习的MDL准则在继承性方面的不足,通过扩充DL测度的组成要素,在其中增加一项旨在反映目标网络结构与当前网络结构拓扑差异度的描述长度指标,改进MDL准则,使其具备处理先验知识的能力。