Preprocessing of ionospheric echo Doppler spectra

The real-time information of the distant ionosphere can be acquired by using the Wuhan ionospheric oblique backscattering sounding system (WIOBSS), which adopts a discontinuous wave mechanism. After the characteristics of the ionospheric echo Doppler spectra were analyzed, the signal preprocessing was developed in this paper, which aimed at improving the Doppler spectra. The results indicate that the preprocessing not only makes the system acquire a higher ability of target detection but also suppresses the radio frequency interference by 6–7 dB. __________ Translated from Journal of Wuhan University (Natural Science), 2006, 52(1): 114–118 [译自: 武汉大学学报(理学版)]     

MnO_2的预处理对LiMn_2O_4正极材料的影响

研究了对前躯体MnO2(EMD)进行不处理、去离子水处理和LiOH处理对合成LiMn2O4正极材料的性能影响。测试结果表明,LiOH处理得到的MnO2杂质含量少,结构稳定,制备的LiMn2O4X射线衍射峰增强,结晶性变好。LiOH处理MnO2制备的LiMn2O4的电化学性能优于去离子水处理MnO2制备的LiMn2O4和不处理MnO2制备的LiMn2O4。LiOH处理、去离子水处理及不处理MnO2制备的LiMn2O4在0.5C的放电比容量分别为115.56mAh/g、109.98mAh/g和100.67mAh/g;1C充放电90次循环下所对应的容量保持率分别为86.79%、86.56%、57.30%。     

基于DCT的PCA人脸识别系统研究

人脸识别是一种重要的生物特征识别技术。本文提出了一种基于DCT的PCA的特征提取方法,该算法先对整个原始人脸图像进行DCT变换得到系数矩阵,再提取包含原始图像大部分信息的少量系数作PCA,提取出特征脸,再进行分类识别。对ORL人脸库仿真实验表明,该方法优于单独DCT与PCA特征提取的识别方法,并且减少了运算量。     

基于机器视觉掘进机位姿检测应用现状与趋势

机器视觉技术依靠非接触、获取信息丰富的特点,在煤矿智能化的进程中得到了广泛应用,同时在煤炭开采中,掘进机的位姿检测有利于掘进机的自动化以及智能化操作进而有利于煤矿智能化进程的推进,不仅能缓解采掘失衡的矛盾,同时能降低工人的劳动强度,本文分析了近几年来机器视觉技术在掘进机位姿检测中的应用现状与趋势,研究了各种掘进机位姿检测方法中所涉及的图像预处理以及位姿检测模型的关键共性问题,并就关键共性问题,提出了机器视觉技术在掘进机位姿检测的应用中,应在图像采集硬件、位姿检测的冗余性以及特征提取的精确性方面做出突破。     

Natural Language Compression on Edge-Guided text preprocessing

This paper presents Edge-Guided (E-G), an optimized text preprocessing technique for compression purposes. It transforms the original text into a word net, which stores all relationships between adjoining words. A specific directed graph is proposed to model this transformation: words are stored in vertices, whereas edges represent word transitions. Thus, the word net has a text representation which reflects the natural word order in the text, so it can be used directly for encoding purposes. A specific coding scheme is described at the top of the word net. It regards a text as a sequence of word transitions, in such a way that each word is encoded by traversing a specific edge from the vertex which stores the preceding word. This accomplishes a 1-order text preprocessing whose output is an intermediate byte representation that can be effectively encoded with universal techniques. This technique is called E-G₁ and performs on some variants.This experience is used to revisit the concept of word net. It is used to identify significative 2-word symbols by performing a specific transformation on frequent edges. The resultant transformed word net appends these 2-word symbols to the original word vocabulary, and allows a specific hierarchical relationship between them and their component words. The transformed approach also enhances the original coding scheme to handle these new features. A new technique, called E-G₂, approximates a 2-order model on words that also support specific variants.Both techniques are studied from empirical and experimental perspectives. Some compressors are also used to analyze the preprocessing ability of E-G with respect to different compression approaches. Competitive space/time trade-offs are achieved when our approaches are used to compress medium-large size texts. The best results are achieved when E-G preprocessing is coupled with high-order compressors such as Prediction by Partial Matching (PPM).     

车牌字符的预处理研究

由于在汽车牌照自动识别系统中，因天气或拍摄角度等原因造成车牌图像模糊、倾斜和光照不均等现象，给车牌的处理带来了很大困难。本文针对这些问题，提出了相应的处理方法，高效地完成了车牌字符的预处理。     

ANSYS前处理与AutoCAD的系统集成

介绍了一种基于ObjectARX的ANSYS前处理与AutoCAD的系统集成方法，开发的系统以面向对象的ObjectARX作为开发工具，实现与AutoCAD的无缝结合，能够方便地将AutoCAD几何模型转换为ANSYS有限元模型。     

一种改进的基于干扰源定向的零点预处理算法

基于在零陷对准干扰信号的情况下，零陷过深导致主瓣展宽、副瓣较高，使得主波束形状不佳等问题，提出了一种改进算法，该算法可以在准确抑制干扰信号的同时保持良好的主波束形状及副瓣电平；同时提出了原算法对干扰来向误差较为敏感的改进办法。计算机仿真结果证明了新算法的有效性。     

文字识别中的图象自适应预处理

为了提高文字识别的正确率，本文比较详细地探讨了手写文字图象在归一化、细化过程中存在的复杂的随机变形，提出了一些有特色的自适应性较强的预处理方法来解决诸如手写文字图象的总尺寸与其构成的笔划宽度一般不成正比等难题，我们还研究出比较符合人眼视觉效果的快速自适应细化算法（375字／秒），这些处理的结果能很稳定地保持原始文字的结构信息，为识别手写的汉字、字母、数字带来了方便。     

三维AVO反演预处理技术试验研究

与常规处理相比,AVO反演预处理在动校正、多次波压制、保幅处理等方面要求更高。针对海上地震资料,对AVO反演预处理中的相对振幅恢复、子波处理、精细切除处理、高精度速度分析与剩余时差校正、多次波衰减、叠前去噪等主要技术进行了试验研究。在上述研究基础上,对DF11区三维地震数据体进行了处理,并对该区Ⅱ上含气砂体的空间展布进行了预测,其结果已被钻井所证实。