高速侵彻复杂介质的实时测定

对目标介质的实时测定与识别是提供稳定、实时的引信决策的重要基础。基于规则的特征提取方法是一种全新思路的实时测定方法，是利用加速度信号的幅值、导数值以及幅值陡变等三个方面提取相应特征值，以确定被侵彻介质的性质和类别。采用这种方法对典型的介质数据集的鉴别结果相当准确，与以往决策算法相比该方法实现简单、应用范围广、灵敏度高。     

基于CPLD控制的DDS数字频率合成器设计

介绍了ADI公司新一代DDS芯片AD9952和XILINX公司新一代CPLD产品XC2C128的主要性能，提出了用XC2C128作控制电路，由AD9952构成宽带、低相噪、低功耗数字合成频率源的设计方案，同时对如何提高DDS频谱纯度进行了探讨，给出了超宽带应用电路解决方案。     

陆东凹陷低熟油特征及形成条件分析

陆东凹陷白垩系所产原油多为低熟油。其特征为低含硫，中含蜡，凝固点中等，粘度中等，密度偏高，饱和烃含量低，芳烃非烃含量偏高。饱和烃色谱特征，生物标记化合物特征和稳定碳同位素组成特征均表明，菌藻类低等生物是重要的成烃母质。     

Ge_xSi_1-x/Si异质结构的近红外吸收光谱测量

测量分析了采用 RRH/VLP—CVD 方法外延生长的 Ge_xSi_(1-x)/Si 异质结构中 Ge_xSi_(1-x)合金薄层的近红外吸收光谱。由谱线计算出 Ge_(0.15)Si_(0.85)与 Ge_(0.45)Si(0.55)合金层的带隙分别为1.02eV 和O.88eV,与相同组分的体合金一致。结果表明用红外吸收光谱测量研究异质结构薄层材料的能带结构及带隙是一种准确、简便的方法。     

用大气压离子质谱法测量高纯氮中的氧

大气压离子质谱（ＡＰＩ－ＭＳ）法以其高灵敏度及特效性，特别适合于分析高纯气体中的痕量物质。我们用ＡＰＩ－ＭＳ法对高纯氮中的痕量氧进行了定量分析，结果表明，测量灵敏度达１×１０－９ｍｏｌ／ｍｏｌ，而测量精度优于±１０％。文中介绍了有关的取样技术及定量方法，并讨论了高纯氮中的Ｈ２Ｏ、ＣＯ２和ＮＯ等含氧化合物对氧含量测量的影响     

Critical point detection in fluid flow images using dynamical system properties

This paper introduces an algorithm for critical point detection in textured fluid flow images. A new measure is defined, based on dynamical system properties, that identifies candidate critical points in an orientation field. The candidates are verified or rejected based on estimates of the local flow field properties. The algorithm can locate partially occluded and degraded flow structures, and applications of this algorithm to experimental flow imagery are included. The algorithm performance is quantified, and it is compared to other detectors.     

Pattern recognition of jet fuels: comprehensive GC×GC with ANOVA-based feature selection and principal component analysis

Two-dimensional comprehensive gas chromatography (GC×GC) is applied to a pattern recognition problem involving classification of jet fuel mixtures. Analysis of variance (ANOVA)-based feature selection is initially used to identify and select chromatographic features relevant to a given classification in two studies. Then, principal component analysis (PCA) was used for pattern recognition classification. In the first study, a 1% volumetric composition change in mixtures of JP-5 and JP-7 jet fuel is readily distinguished. In this first study, the effective combination of GC×GC, ANOVA-based feature selection and PCA is developed and evaluated as a chemical analysis tool. The second study involved the analysis of three samples each of three different jet fuel types, JP-5, JP-8, and JP-TS, as well as blends incorporating two or three jet fuels. Each of the nine jet fuel samples originated from various geographic locations within the United States. These samples were analyzed in order to determine if a classification based on fuel type is possible in the presence of sample variability (due to geographic origin) with GC×GC/pattern recognition analysis. Chromatographic features that are adept at classification of jet fuel type and are not sensitive to geographic origin of the sample were generated for the sample set consisting of the original fuel types as well as mixtures of the three different, original jet fuels. The combination of GC×GC with ANOVA-based feature selection was found to be a useful tool to enhance the chemical selectivity, and thus the classification power of the analytical procedure, when coupled with PCA.     

Address block location on envelopes using Gabor filters

The large volume of mail and the increased cost of handling it has made postal automation an important domain for pattern recognition and computer vision research. A substantial amount of work is being done to design an automatic mail sorting system which can read and interpret the destination address on a mail piece and direct it to the appropriate bin. Robust optical character recognition (OCR) systems are now available which can read printed characters with great accuracy (> 99%). But, in order to read the destination address, the region in the image containing the address must first be located. Even though several approaches to address block location have been proposed in the literature, it remains a difficult problem. A simple method is presented for automatically identifying regions in envelope images which are candidates for being the destination address. The envelope image is considered to contain different textured regions, one of which corresponds to the text-content in the image. Thus, a texture-based segmentation method is used to identify the regions of text in the image. The method for texture discrimination is based on Gabor filters which have been successfully used earlier for a variety of texture classification and segmentation tasks. It is shown that only a small number of even-symmetric Gabor filters are needed in this application. The success of the texture-based segmentation algorithm for identifying address blocks is demonstrated on a number of test images. These results also demonstrate the invariance of the method to the orientation of text in the envelope image and the variations in the size and font of the text.     

两种状态下GPS时间比对的频谱特性分析

为了了解受ＳＡ效应影响的ＧＰＳ时间比对特性，１９９２年初进行了一些实验，实验的数据取样时间为１０秒，卫星跟踪时间为１小时。频谱分析的结果表明：１）正常状态下，ＧＰＳ时间比对的频谱特性是基本平坦的，没有明显的周期现象，噪声过程为调相白噪声；２）当ＧＰＳ时间比对受ＳＡ效应影响时，低频谱较明显，有明显的周期现象，其中５－１５分钟的周期信号约占７７％。这就是导致ＧＰＳ时间比对精度显著下降的原因。