BP神经网络在缺失数据估计中的应用

由于飞行参数记录系统所记录的数据很容易被污染,所以对飞参数据进行预处理已显得十分重要,而预处理的一项重要内容就是对缺失参数数据进行合理且有效地估计,真实地反映飞行器当时的状态.通过分析神经网络理论和飞参数据特征,提出了一种基于BP神经网络的缺失数据估计的方法,有效地解决了目前飞行参数记录系统记录数据时缺失数据的问题.利用某型飞机真实的数据进行仿真,结果表明了这种方法是可行且有效的.     

词频规范化改善信息检索查准率

研究了词频规范化，通过实例指出并分析了极大规范化词频、对数词频和平均词频这3种现有的词频规范化方法的不足，在理论上探究了影响词频规范化的因素。通过引入新参数的方法对词频规范化予以改进，以试错法给出了3种可能的词频规范化形式，并经数学推导，最终给出了改进的词频规范化方法，并通过实验验证了改进的词频规范化形式的有效性。     

DETECTION OF SCANS

Abstract

Most automatic parallelizes are based on the detection of independent operations. Dependence analysis is mainly a syntactical process, in which the actual data transformations are ignored. There is another source of parallelism, which relies on semantical information, namely the detection of reductions and scans. Scans and reductions are quite frequent in scientific codes and are implemented efficiently on most parallel computers. We present here a new Scan detector which is based on the normalization of systems of recurrence equations. This allows the detection of scans in loops nests of arbitrary depth and on multi-dimensional arrays, and gives a uniform treatment for scalar reductions, array reductions, and arrays of reductions.     

模糊数学在机械设计综合评判中的应用

以模糊数学为理论基础,通过对高压大流量乳化液泵结构方案的分析,建立了机械产品结构方案的模糊综合评判模型,从而将人们头脑中的模糊概念应用于计算机辅助设计,为机械产品设计提供了一种较为客观的选优方式。     

Score normalization in multimodal biometric systems

Multimodal biometric systems consolidate the evidence presented by multiple biometric sources and typically provide better recognition performance compared to systems based on a single biometric modality. Although information fusion in a multimodal system can be performed at various levels, integration at the matching score level is the most common approach due to the ease in accessing and combining the scores generated by different matchers. Since the matching scores output by the various modalities are heterogeneous, score normalization is needed to transform these scores into a common domain, prior to combining them. In this paper, we have studied the performance of different normalization techniques and fusion rules in the context of a multimodal biometric system based on the face, fingerprint and hand-geometry traits of a user. Experiments conducted on a database of 100 users indicate that the application of min–max, z-score, and tanh normalization schemes followed by a simple sum of scores fusion method results in better recognition performance compared to other methods. However, experiments also reveal that the min–max and z-score normalization techniques are sensitive to outliers in the data, highlighting the need for a robust and efficient normalization procedure like the tanh normalization. It was also observed that multimodal systems utilizing user-specific weights perform better compared to systems that assign the same set of weights to the multiple biometric traits of all users.     

A face recognition system based on automatically determined facial fiducial points

In this paper, a completely automatic face recognition system is presented. The method works on color images: after having localized the face and the facial features, it determines 24 facial fiducial points, and characterizes them applying a bank of Gabor filters which extract the peculiar texture around them (jets). Recognition is realized measuring the similarity between the different jets. The system is inspired by the elastic bunch graph method, while it does no assumption on the scale, pose, and the background. Comparison with standard algorithms is presented and discussed.     

Radiometric correction of multi-temporal Landsat data for characterization of early successional forest patterns in western Oregon

Detecting and characterizing continuous changes in early forest succession using multi-temporal satellite imagery requires atmospheric correction procedures that are both operationally reliable, and that result in comparable units (e.g., surface reflectance). This paper presents a comparison of five atmospheric correction methods (2 relative, 3 absolute) used to correct a nearly continuous 20-year Landsat TM/ETM+ image data set (19-images) covering western Oregon (path/row 46/29). In theory, full absolute correction of individual images in a time-series should effectively minimize atmospheric effects resulting in a series of images that appears more similar in spectral response than the same set of uncorrected images. Contradicting this theory, evidence is presented that demonstrates how absolute correction methods such as Second Simulation of the Satellite Signal in the Solar Spectrum (6 s), Modified Dense Dark Vegetation (MDDV), and Dark Object Subtraction (DOS) actually make images in a time-series somewhat less spectrally similar to one another. Since the development of meaningful spectral reflectance trajectories is more dependant on consistent measurement of surface reflectance rather than on accurate estimation of true surface reflectance, correction using image pairs is also tested. The relative methods tested are variants of an approach referred to as “absolute-normalization”, which matches images in a time-series to an atmospherically corrected reference image using pseudo-invariant features and reduced major axis (RMA) regression. An advantage of “absolute-normalization” is that all images in the time-series are converted to units of surface reflectance while simultaneously being corrected for atmospheric effects. Of the two relative correction methods used for “absolute-normalization”, the first employed an automated ordination algorithm called multivariate alteration detection (MAD) to statistically locate pseudo-invariant pixels between each subject and reference image, while the second used analyst selected pseudo-invariant features (PIF) common to the entire image set. Overall, relative correction employed in the “absolute-normalization” context produced the most consistent temporal reflectance response, with the automated MAD algorithm performing equally as well as the handpicked PIFs. Although both relative methods performed nearly equally in terms of observed errors, several reasons emerged for preferring the MAD algorithm. The paper concludes by demonstrating how “absolute-normalization” improves (i.e., reduces scatter in) spectral reflectance trajectory models used for characterizing patterns of early forest succession.     

非汉字词语的性质和规范原则--非汉字词语问题讨论会纪要

本文记录了对非汉字词语的不同看法，指出在目前所存在的各种问题。这一现状不利于我国语文建设，建议尽快制定出非汉字词语的规范、标准，并提出了规范原则和方法。     

红土化学成分的变化特征

红土是母岩经历不同程度的红土化作用形成的，不同地区、不同母岩、不同气候条件形成的不同类型红土，其主要化学成分之间存在统计规律，研究结果表明：红土的化学成分都是以SiO2,Fe2O3和Al2O3为主,随着SiO2含量的减小，Fe2O3,Al2O3和R2O3的含量增大；而红土的pH值、烧失量随着R2O3含量的增大而增大；归一化的SiO2与倍半氧化物R2O3关系不论是以含量计算或分子量计算，都存在二项式的分布规律，红土的化学成分实质上是红土化作用结果的反映。     

一种用于识别用户解释冲突的算法

对于面向对象数据库的规范化理论 ,用户解释与模式的冲突是一个关键问题 .本文引入一种统一的面向对象模式和用户解释的 (0 - 1)矩阵表示方法 ,并在此基础上给出了用户解释与模式的冲突的多项式时间的识别算法 ,为面向对象数据库的规范化理论的研究开辟出一个新途径