利用船载GPS姿态仪提高磁场的测量精度

舰船的磁场是舰船物理场的重要信息,对它的测量对研究舰船物理场的特征具有重要的意义。然而,在海水中舰船的磁场信息势必受到舰船姿态信息变化的影响,因此提出修正舰船姿态信息对磁场测量影响的方法。本文具体论述了用船载GPS姿态仪获取舰船姿态信息的原理和实现方法,并提出了用舰船姿态信息修正舰船磁场的计算方法,从而提高舰船磁场的测量精度。     

时间统一系统同步误差测量方法研究

传统的人工时间同步误差的测量方法存在操作复杂和效率低下的缺点。为解决这些问题,提出一种同步误差的测量方法,该方法基于复杂可编程逻辑器件（CPLD）技术,并利用全球定位系统来测量时间统一系统的同步误差。相对于传统的测量方法,该方法显著提高了同步误差测量的智能化程度,减轻了测试人员的工作量。通过实验,验证了本设计方案的可行性及正确性。     

Passenger travel characteristics and bus operational states: a study based on IC card and GPS data in Yinchuan,China

ABSTRACT

In recent years, public transport has been developing rapidly and producing large amounts of traffic data. Emerging big data-mining techniques enable the application of these data in a variety of ways. This study uses bus intelligent card (IC card) data and global positioning system (GPS) data to estimate passenger boarding and alighting stations. First, an estimation model for boarding stations is introduced to determine passenger boarding stations. Then, the authors propose an innovative uplink and downlink information identification model (UDI) to generate information for estimating alighting stations. Subsequently, the estimation model for the alighting stations is introduced. In addition, a transfer station identification model is also developed to determine transfer stations. These models are applied to Yinchuan, China to analyze passenger flow characteristics and bus operations. The authors obtain passenger flows based on stations (stops), bus lines, and traffic analysis zones (TAZ) during weekdays and weekends. Moreover, average bus operational speeds are obtained. These findings can be used in bus network planning and optimization as well as bus operation scheduling.     

An analysis of the factors influencing differences in survey-reported and GPS-recorded trips

Recent advances in global positioning systems (GPS) technology have resulted in a transition in household travel survey methods to test the use of GPS units to record travel details, followed by the application of an algorithm to both identify trips and impute trip purpose, typically supplemented with some level of respondent confirmation via prompted-recall surveys. As the research community evaluates this new approach to potentially replace the traditional survey-reported collection method, it is important to consider how well the GPS-recorded and algorithm-imputed details capture trip details and whether the traditional survey-reported collection method may be preferred with regards to some types of travel. This paper considers two measures of travel intensity (survey-reported and GPS-recorded) for two trip purposes (work and non-work) as dependent variables in a joint ordered response model. The empirical analysis uses a sample from the full-study of the 2009 Indianapolis regional household travel survey. Individuals in this sample provided diary details about their travel survey day as well as carried wearable GPS units for the same 24-h period. The empirical results provide important insights regarding differences in measures of travel intensities related to the two different data collection modes (diary and GPS). The results suggest that more research is needed in the development of workplace identification algorithms, that GPS should continue to be used alongside rather than in lieu of the traditional diary approach, and that assignment of individuals to the GPS or diary survey approach should consider demographics and other characteristics.     

水底清淤装备控制系统研究与实现

本文针对我国重点世纪工程-港珠澳大桥岛隧工程在施工中碰到的铺设整平已完成的碎石基床上出现严重回淤现象的问题,提出了使用一套定点清淤装置解决该问题的应用方法。该方法通过升降调节油缸以调整吸头的垂直高度,在垄沟进行清淤作业时保证清淤后基床的平整度并保护吸头不被基石阻挡而损坏。为了补偿因挠度差异产生的轴变化量,根据采集到的GPS信号通过PID控制方式实时调节油缸伸缩。本文从清淤系统的PLC电控方面展开,详细介绍了清淤功能的实现方式。     

基于导航战的GPS压制式干扰技术研究

简要介绍了GPS导航战策略和卫星导航系统在现代战争中的作用,对基于导航战的GPS压制式干扰技术的原理与性能做了一定的分析,并得出了一些有价值的结论。     

基于PDA和GPS实时坐标转换系统的设计与实现

为了满足GPS海上打桩定位的需要,开发了相应的PDA实时坐标转换软件。介绍了基于PDA和GPS的实时坐标转换系统的基本原理和串口通信模块。详细介绍了该系统的开发和设计,介绍了系统与GPS打桩定位系统的集成。试验结果表明,该系统精度高、操作简单,提高了打桩定位的精度和效率。     

基于距离准则的地图匹配算法研究

为了弥补车辆导航中位置点匹配算法的不足,对轨迹曲线匹配的思想进行了必要的介绍,并重点从距离要素出发,对匹配准则进行了研究。在分析了各种常见距离定义的不足后,提出了基于面积法的距离匹配准则,并对距离准则的算法设计和适用性进行了详细的分析和描述。结论表明,采用该算法后的总体定位精度优于GPS的定位精度,算法准确性也比位置点匹配高。     

土地调查用GPS/PDA实时差分定位系统的坐标转换及精度测试

基于GPS/PDA技术的土地调查用实时差分定位系统能进行全数字化的数据采集、存储和处理.为将GPS测得的WGS-84坐标系下的点位坐标转换成土地利用数据的当地坐标系,采用平面四参数转换模型并进行基准点的兼容性检验.在北京等试点的大量测试表明,该系统能达到厘米级定位精度.     

基于无线定位技术的电子关锁的设计

无线定位电子关锁是在普通的射频电子关锁的基础上,融合了GPS、GPRS技术。文章介绍了GPS、GPRS、单片机等技术在电子关锁上的应用方案,对各个模块进行了介绍;较为详细地描述了软件总体设计思想、通信命令及格式等。