基于LPC2138的超市收银机系统设计

给出一种基于Philips公司的ARM7 LPC2138微控制器的超市收银管理系统的设计方法。该系统不仅实现商品价目表（PLU）,销售日志保存、记录和打印,中英文字符和数字输入等基本功能,还实现了对超市环境参数监测报警、语音播报及语音识别等功能。     

Reduced cross‐talk in shutter‐glass‐based stereoscopic LCD

Abstract— It is expected that 3‐D will be the next step in the enhanced viewing experience. At present, there are two competing 3‐D technologies for glasses‐based consumer TVs: active shutter glasses and passive polarized glasses. With the ongoing reduction in response time of liquid‐crystal displays (LCDs), this article will focus on shutter‐glass‐based stereoscopic LCDs. In this paper, the properties of such a display system is described and it is demonstrated that by adding a line‐scanning backlight, the cross‐talk can be reduced to less than 1.4%, allowing for excellent 3‐D portrayal. For images of extreme contrast, this is perceivable, but not judged annoying by a panel of expert viewers. Which characteristics of the display and shutter glasses that should be optimized to create an inexpensive, cross‐talk‐free, 3‐D LCD are discussed.     

电阻抗扫描成像计算机辅助诊断方法研究

为了提高电阻抗扫描成像EISI(Electrical Impedance Scanning Imaging)在乳腺疾病检查方面的准确性,将独立分量方法(ICA)应用于EISI数据的特征提取,并结合支持向量机(SVM)进行乳腺疾病计算机辅助诊断(CAD)。实验结果表明:ICA方法所提取的特征对于乳腺疾病分类是有效的。对于良性肿瘤和恶性肿瘤的鉴别,提出的CAD方法灵敏度为74.2%,特异度为82.8%,准确度为80%。结合所提出的CAD方法和传统的EISI检查方法,可以提高EISI在乳腺疾病检查方面的可靠性,降低假阳性率,避免对良性肿瘤患者进行活检。     

Classifying species of individual trees by intensity and structure features derived from airborne laser scanner data

The objective of this study was to identify candidate features derived from airborne laser scanner (ALS) data suitable to discriminate between coniferous and deciduous tree species. Both features related to structure and intensity were considered. The study was conducted on 197 Norway spruce and 180 birch trees (leaves on conditions) in a boreal forest reserve in Norway. The ALS sensor used was capable of recording multiple echoes. The point density was 6.6 m^− 2. Laser echoes located within the vertical projection of the tree crowns, which were assumed to be circular and defined according to field measurements, were attributed to three categories: “first echoes of many”, “single echoes”, or “last echoes of many echoes”. They were denoted FIRST, SINGLE, and LAST, respectively. In tree species classification using ALS data features should be independent of tree heights. We found that many features were dependent on tree height and that this dependency influenced selection of candidate features. When we accounted for this dependency, it was revealed that FIRST and SINGLE echoes were located higher and LAST echoes lower in the birch crowns than in spruce crowns. The intensity features of the FIRST echoes differed more between species than corresponding features of the other echo categories. For the FIRST echoes the intensity values tended to be higher for birch than spruce. When using the various features for species classification, maximum overall classification accuracies of 77% and 73% were obtained for structural and intensity features, respectively. Combining candidate features related to structure and intensity resulted in an overall classification accuracy of 88%.     

Effects of different sensors, flying altitudes, and pulse repetition frequencies on forest canopy metrics and biophysical stand properties derived from small-footprint airborne laser data

Canopy height distributions were created from small-footprint airborne laser scanner (ALS) data collected over 40 field sample plots with size 1000 m² located in mature conifer forest. ALS data were collected with two different instruments, i.e., the ALTM 1233 and ALTM 3100 laser scanners (Optech Inc.). The ALTM 1233 data were acquired at a flying altitude of 1200 m and a pulse repetition frequency (PRF) of 33 kHz. Three different acquisitions were carried out with ALTM 3100, i.e., (1) a flying altitude of 1100 m and a PRF of 50 kHz, (2) a flying altitude of 1100 m and a PRF of 100 kHz, and (3) a flying altitude of 2000 m and a PRF of 50 kHz. Height percentiles, mean and maximum height values, coefficients of variation of the heights, and canopy density at different height intervals above the ground were derived from the four different ALS datasets and for single + first and last echoes of the ALS data separately. The ALS-derived height- and density variables were assessed in pair-wise comparisons to evaluate the effects of (a) instrument, (b) flying altitude, and (c) PRF. A systematic shift in height values of up to 0.3 m between sensors when the first echoes were compared was demonstrated. Also the density-related variables differed significantly between the two instruments. Comparisons of flying altitudes and PRFs revealed upwards shifted canopy height distributions for the highest flying altitude (2000 m) and the lowest PRF (50 kHz). The distribution of echoes on different echo categories, i.e., single and multiple (first and last) echoes, differed significantly between acquisitions. The proportion of multiple echoes decreased with increasing flying altitude and PRF. Different echo categories have different properties since it is likely that single echoes tend to occur in the densest parts of the tree crowns, i.e., near the apex where the concentration of biological matter is highest and distance to the ground is largest. To assess the influence of instrument, flying altitude, and PRF on biophysical properties derived from ALS data, regression analysis was carried out to relate ALS-derived metrics to mean tree height (h_L) and timber volume (V). Cross validation revealed only minor differences in precision for the different ALS acquisitions, but systematic differences between acquisitions of up to 2.5% for h_L and 10.7% for V were found when comparing data from different acquisitions.     

基于身份密码的安全电子邮件系统

针对现有电子邮件系统中的安全性问题,采用基于身份的密码体制和基于内容的过滤扫描技术,构建具有反垃圾／反病毒功能的邮件服务器及具有涉密扫描功能的邮件网关服务器,设计并实现了邮件系统客户端及其必备管理控制中心。系统具有扫描并过滤涉密邮件、加密或解密邮件、签名或认证邮件等功能,能够满足在不可控、动态和松散企业组织成员问的安全通信。     

气象水文到报监测的实时性设计

到报监测是气象水文数据传输、处理等的重要环节,其实时性是关键设计目标.通过分析文件目录扫描方法和消息通知机制的应用特点,结合气象水文资料传输、处理规程及应用模式,重点阐述了结合实时性和可靠性要求的到报监测方法,并给出一种重构性强、应用灵活的到报监测模块的设计方案.     

基于改进PrefixSpan的序列模式挖掘算法

针对PrefixSpan算法构造投影数据库开销大的问题,提出一种基于改进PrefixSpan的序列模式挖掘算法SPMIP。该方法通过添加剪枝步和减少某些特定序列模式生成过程的扫描,来减少投影数据库的规模及扫描投影数据库的时间,提高算法效率,并最终得到需要的序列模式。实验结果证明在获得序列模式不受影响情况下,SPMIP算法比PrefixSpan算法效率更高。     

正规网格等值线的虚路径扫描算法

等值线图在工程分析和计算领域有着广泛的应用。该文以正规化的采样数据为研究对象,提出了一种全新的虚路径扫描算法。算法在数据网格基础之上构筑一虚拟的路径网格,利用路径网格上的线段（虚路径）来记录等值点的追踪路径信息。所有等值线的虚路径的捕获只需通过一次性扫描即可完成,不仅提高了追踪效率,而且避免了以往等值线追踪算法初始点选择困难、网格出口边判断复杂等一系列问题。算法的另一优点是追踪结果的精度是可控的,取决于等值点如何取值。该算法在土地定级中的作用分等值线图绘制中得到很好的应用。虚路径的思想同样适用于非正规的采样数据。     

Scanning electron microscopic observations on micro-organisms in the root nodules of Tribulus terrestris L. (Zygophyllaceae)

Scanning electron microscopic observations were made on the micro-organisms of root nodules of Tribulus terrestris L. The results showed that nodules of T. terrestris contained dual infection consisting of Rhizobium sp. and Newmania karachiensis. Based on these observations, T. terrestris should be grouped with nonlegume Parasponia-type bacterial nodules.