基于尺度相关性的旋转不变纹理图像渐进式检索算法

在常用的基于小波变换域旋转不变纹理图像检索算法中,由于存在方向信息提取有限且多尺度间系数相关性被忽略的局限性,检索效率受到影响。提出一种基于尺度相关性的渐进式旋转不变纹理图像检索算法。该算法首先采用Log-polar变换与非下采样Contourlet变换组合的方式获取具备旋转不变性的多尺度多方向变换系数,然后利用广义高斯模型拟合低通波段的全局结构信息作为粗判依据,方向子带间的尺度相关信息则采用非高斯双变量模型拟合,并作为精细渐进式检索的特征变量。基于Brodatz标准纹理库的实验结果表明,与小波变换及基于层内关系模型方法相比,该方法能以更低的特征维数获得更高的检索效率及检索准确率,是一种进行旋转纹理检索的有效手段。     

双变量EMD分析的平面离散曲线光顺方法

曲线的光顺在计算机辅助设计及其相关制造业中都有着重要作用.通过把平面离散曲线当作非平稳信号来处理,提出了一种双变量经验模式分解(EMD)的平面数字曲线光顺方法.方法首先将平面数字曲线的各个变量分离,参数化为两个一维信号;然后运用一维EMD方法对一维化的信号进行滤波处理,去除高频噪声;最后对两个处理好的信号进行合成,得到...     

Statistical Algorithms for Designing Geophysical Surveys to Detect UXO Target Areas

The U.S. Department of Defense is in the process of assessing and remediating closed, transferred, and transferring military training ranges across the United States. Many of these sites have areas that are known to contain unexploded ordnance (UXO). Other sites or portions of sites are not expected to contain UXO, but some verification of this expectation using geophysical surveys is needed. Many sites are so large that it is often impractical and/or cost prohibitive to perform surveys over 100% of the site. In such cases, it is particularly important to be explicit about the performance required of the surveys. This article presents the statistical algorithms developed to support the design of geophysical surveys along transects (swaths) to find target areas (TAs) of anomalous geophysical readings that may indicate the presence of UXO. The algorithms described here determine (1) the spacing between transects that should be used for the surveys to achieve a specified probability of traversing the TA, (2) the probability of both traversing and detecting a TA of anomalous geophysical readings when the spatial density of anomalies within the TA is either uniform (unchanging over space) or has a bivariate normal distribution, and (3) the probability that a TA exists when it was not found by surveying along transects. These algorithms have been implemented in the Visual Sample Plan (VSP) software to develop cost-effective transect survey designs that meet performance objectives.     

Bivariate p-boxes and maxitive functions

We give necessary and sufficient conditions for a maxitive function to be the upper probability of a bivariate p-box, in terms of its associated possibility distribution and its focal sets. This allows us to derive conditions in terms of the lower and upper distribution functions of the bivariate p-box. In particular, we prove that only bivariate p-boxes with a non-informative lower or upper distribution function may induce a maxitive function. In addition, we also investigate the extension of Sklar’s theorem to this context.     

Bivariate threshold models for genetic evaluation of susceptibility to and ability to recover from mastitis in Danish Holstein cows

Mastitis in dairy cows is an unavoidable problem and genetic variation in recovery from mastitis, in addition to susceptibility, is therefore of interest. Genetic parameters for susceptibility to and recovery from mastitis were estimated for Danish Holstein-Friesian cows using data from automatic milking systems equipped with online somatic cell count measuring units. The somatic cell count measurements were converted to elevated mastitis risk, a continuous variable [on a (0–1) scale] indicating the risk of mastitis. Risk values >0.6 were assumed to indicate that a cow had mastitis. For each cow and lactation, the sequence of health states (mastitic or healthy) was converted to a weekly transition: 0 if the cow stayed within the same state and 1 if the cow changed state. The result was 2 series of transitions: one for healthy to diseased (HD, to model mastitis susceptibility) and the other for diseased to healthy (DH, to model recovery ability). The 2 series of transitions were analyzed with bivariate threshold models, including several systematic effects and a function of time. The model included effects of herd, parity, herd-test-week, permanent environment (to account for the repetitive nature of transition records from a cow) plus two time-varying effects (lactation stage and time within episode). In early lactation, there was an increased risk of getting mastitis but the risk remained stable afterwards. Mean recovery rate was 45% per lactation. Heritabilities were 0.07 [posterior mean of standard deviations (PSD) = 0.03] for HD and 0.08 (PSD = 0.03) for DH. The genetic correlation between HD and DH has a posterior mean of ?0.83 (PSD = 0.13). Although susceptibility and recovery from mastitis are strongly negatively correlated, recovery can be considered as a new trait for selection.     

A dynamic investigation of cognitive dedifferentiation with control for retest: Evidence from the Swiss Interdisciplinary Longitudinal Study on the Oldest Old.

Empirical examinations of the hypothesis of dedifferentiation of cognitive abilities in old and very old age (a) do not account for possible retest effects, which consequently may yield biased estimates of age effects, and (b) focus on time-independent relations (e.g., number of latent constructs, correlations between latent or measured variables). The authors applied a structural equation model with statistical control for retest effects to investigate the dynamic relations between a marker of perceptual speed (cross out) and a marker of verbal fluency (category-fruits). Longitudinal data are from 5 waves of the Swiss Interdisciplinary Longitudinal Study on the Oldest Old (N = 377, baseline age range = 79.5- 84.5 years). The authors found that, independently of retest effects, performance on the cross-out task affected changes in performance on the category task while the opposite did not hold true. This analytical technique could be applied to various markers of broad fluid-mechanic and broad crystallized-pragmatic components of cognition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

用“匈牙利算法”求解一类最优化问题

文章给出了改进的“匈牙利算法”的一般步骤和Matlab实现的通用程序,可用此来求解著名的指派问题、婚配问题、锁具装箱问题,以及任何完全或非完全的赋权二分图的最优(大)匹配问题。     

The distribution of sums, products and ratios for Lawrance and Lewis's bivariate exponential random variables

We derive the exact distributions of R=X+Y, P=XY and W=X/(X+Y) and the corresponding moment properties when X and Y follow Lawrence and Lewis's bivariate exponential distribution. The expressions turn out to involve special functions. We also provide extensive tabulations of the percentage points associated with the distributions. These tables—obtained using intensive computing power—will be of use to practitioners of the bivariate exponential distribution.     

基于NABEMD的飞行参数噪声能量估计与消除

飞参系统(Flight Data Recorder,简称FDR)记录的飞行参数采样率低、噪声与野值混杂且呈非线性非平稳性的特点使得传统噪声处理方法难以适用,因而提出一种基于噪声辅助复数据经验模态分解(Noise Assisted Bivariate Empirical Mode Decomposition,简称NABEMD)的噪声能量估计与消除方法,用于飞行参数的降噪问题。该方法首先利用飞行参数和高斯白噪声构造复数据并进行BEMD分解,然后根据虚部各层内禀模态函数(Intrinsic Mode Function,简称IMF)的能量来估计实部IMF包含的噪声能量,最后根据噪声能量估计值对IMF进行分层处理得到降噪后的信号。仿真结果表明,本文方法相对于现有方法具有一定优势,可以进一步提高飞行参数的降噪精度。     

二元多项式法在烧结机尾断面图像校正中的运用

针对烧结机尾断面图像,提出了运用二元多项式法对其进行图像校正,实验结果表明选用合适的二元多项式的次数和标定点数能有效地对烧结机尾断面图像进行校正.