卫星导航接收机的抗干扰研究

GPS是一种高精度的导航系统,主要针对GPS抗干扰系统进行研究,介绍了GPS接收机信号组成以及接收机的工作原理,并针对GPS接收机的主要干扰信号给出了五种GPS接收机的抗干扰方法。     

基于ＤＳＰＢｕｉｌｄｅｒ全数字接收机定时载波同步算法的实现

讨论了全数字接收机中同步算法的设计与实现,给出了基于Ｇａｒｄｎｅｒ反馈环路的定时 同步算法和基于数字Ｃｏｓｔａｓ环的载波相位补偿算法的定点实现方案,并在Ａｌｔｅｒａ公司的ＤＳＰ Ｂｕｉｌｄｅｒ上实现了该算法．计算机仿真和ＦＰＧＡ（ＦｉｅｌｄＰｒｏｇｒａｍｍａｂｌｅＧａｔｅＡｒｒａｙ）实现都验证了其有 效性,测试结果表明,该系统信噪比恶化小于１５ｄＢ,时钟捕捉带大于±１％,载波频差捕捉带 大于±４％．     

基于FPGA的中频数字接收机设计与实现

介绍了一种基于FPGA的中频数字接收机的设计与实现,给出了系统实现的总体方案,并阐述了各部分硬件电路的设计。重点对FPGA内部各主要功能模块做了详细阐述,对各个模块的设计方法以及实现过程进行了细致描述,给出了各模块的具体实现的顶层文件,并对系统功能扩展做了简要说明。     

知识扩散场的建立与实证分析

本文引入了物理学中势能、势差、能量转换的概念,建立知识扩散场。提出了一种用于描述吸收体在知识扩散过程中知识发展状态的经济模型,用它阐明知识扩散的条件、过程,及在扩散的不同阶段各个影响因素的作用机理。最后进行了实证检验。     

从信息的“消费者”到“生产者”——网络传播中受众地位变化分析

网络媒体的出现给新闻传播行为带来了太多的冲击波,其中最突出的就是“受众地位”的变化。网络打破了以往“以传者为中心”的传播模式,逐渐走向“以受众为中心”的符合全球传播观念发展规律的全新传播模式,受众开始通过网络从信息的“消费者”向信息的“生产者”转化。在看到这个转化带来的优势的同时,其变化动因和带来的弊端也值得进行研究分析。     

RGB POV在点阵旋转屏中的应用及其电源解决方案

为了研究并优化RGB发光二极管旋转显示屏及其电源解决方案,在系统仿真研究的基础上,设计并改善了无线能量传送电路、无线能量接收电路以及低电压单片机控制系统,在Keil-汇编语言环境下编写了单片机控制程序,制作出PCB电路板并进行了软硬件调试。实验结果表明:所设计的RGB发光二极管旋转显示屏具有良好实用性,其无线能量传送的供电方案完美解决了电源问题,为产品化提供了有力支持。     

Utility of icteric index in clinical laboratories: more than a preanalytical indicator

IntroductionTotal bilirubin tests are highly demanded in clinical laboratories. Since icteric index (I-index) has zero cost, we aimed to evaluate its clinical utility and cost-effectiveness to determine if total bilirubin is necessary to be tested. We took into account if haemolysis could interfere to icteric index determination.Material and methodsRetrospectively we reviewed I-index results in two cohorts (43,372 and 8507 non-haemolysed and haemolysed samples, respectively). All determinations were done using Alinity c chemistry analysers (Abbott Diagnostics). Receiver operating characteristic (ROC) curve was used to determine the optimal index cut-off to discriminate between normal and abnormal bilirubin concentration (20.5 µmol/L).ResultsThe ROC curve analysis suggested 21.4 µmol/L as the optimal I-index cut-off but differences in sensitivity and specificity were detected between patient derivation. For rejecting purpose, 15.4 µmol/L and 17.1 µmol/L I-index thresholds were selected based on patient derivation (inpatients and emergency room; and primary care and outpatients, respectively) with 97% sensitivity and 0.25% false negative results. Sensitivity was much lower in haemolysed samples. We selected 34.2 µmol/L I-index as threshold to detect hyperbilirubinemia with 99.7% specificity and 0.26% false positive results, independent of haemolysis. With the icteric index cut-offs proposed, we would save 66% of total bilirubin requested and analyse total bilirubin in around 2% of samples without total bilirubin requested.ConclusionsThis study supports the use of I-index to avoid bilirubin determination and to identify patients with hyperbilirubinemia. This work considers that the economic and test savings could help to increase the efficiency in clinical laboratories.     

卫星电视信号传输、接收与调试

介绍了卫星电视信号的上行发射、星载转发和下行接收,并讨论了卫星电视信号下行接收天线焦距、极化方式、方位角和仰角的计算公式与调试方法。     

The Hong Kong Behaviour Checklist for Primary Students: Developing a brief dyslexia screening measure

The authors report on the development of a brief dyslexia screening measure based on revising the 65-item Hong Kong Behaviour Checklist of Specific Learning Difficulties in Reading and Writing. Teachers’ ratings of 1063 primary students aged 6–14 years on the behaviour checklist provided data for its psychometric evaluation using traditional measurement and Rasch measurement model analyses. Rasch scaling suggested that the revised 36-item checklist could be regarded as a unidimensional scale that assesses global dyslexic dysfunction, and receiver operating characteristics analysis suggested that a score of 18 could be an optimal cut-off score when it is used as a dyslexia screening measure. The validity of this revised checklist was supported by its substantial and significant correlations with external measures of literacy and cognitive skills. Implications of the findings for the use of adaptive testing to provide an effective procedure for screening are discussed.     

Impact of product involvement,message format,and receiver sex on the efficacy of comparative advertising messages

Although comparative advertising accounts for nearly half of all television commercial messages, much remains to be learned about its use and effectiveness. This investigation probed the role and impact of receiver involvement in product class, comparative message format, and receiver sex on the relative effectiveness of comparative advertising messages. The results indicate that females and males respond uniquely to comparative advertising, revealing consistent patterns regarding both circumstances and approaches. The findings of this study suggest important nuances for advertising professionals in their efforts to design and to target comparative messages.