基于Hadoop平台的XML Twig查询处理方法

为解决半结构化XML大数据的处理分析问题,分析了Twig查询结构特点和Hadoop平台架构特征。基于Hadoop平台,通过对XML数据的水平切分,设计了XML数据在HDFS上的分布式存储策略;将Twig查询分解为线性路径,实现了基于MapReduce编程模型的并行查询方法。最后通过实验验证了该方法的有效性。     

基于模糊综合评价的关联性能分析

针对单一指标无法较完整的对数据融合中的数据关联效果进行评估的问题,本文提出应用模糊综合评价法,综合多个指标、多个场景对数据关联的性能进行综合评估.实验表明,该模型可以对数据关联的性能进行定量评价,并且能够对不同关联算法的性能进行比较.     

Testability integrated evaluation method based on testability virtual test data

Testability virtual test is a new test method for testability verification, which has the advantages such as low cost, few restrictions and large sample of test data. It can be used to make up the deficiency of testability physical test. In order to take the advantage of testability virtual test data effectively and to improve the accuracy of testability evaluation, a testability integrated eval- uation method is proposed in this paper based on testability virtual test data. Considering the char- acteristic of testability virtual test data, the credibility analysis method for testability virtual test data is studied firstly. Then the integrated calculation method is proposed fusing the testability vir- tual and physical test data. Finally, certain helicopter heading and attitude system is presented to demonstrate the proposed method. The results show that the testability integrated evaluation method is feasible and effective.     

A numerical model for bird strike on sidewall structure of an aircraft nose

In order to examine the potential of using the coupled smooth particles hydrodynamic(SPH) and finite element(FE) method to predict the dynamic responses of aircraft structures in bird strike events, bird-strike tests on the sidewall structure of an aircraft nose are carried out and numerically simulated. The bird is modeled with SPH and described by the Murnaghan equation of state, while the structure is modeled with finite elements. A coupled SPH–FE method is developed to simulate the bird-strike tests and a numerical model is established using a commercial software PAM-CRASH. The bird model shows no signs of instability and correctly modeled the break-up of the bird into particles. Finally the dynamic response such as strains in the skin is simulated and compared with test results, and the simulated deformation and fracture process of the sidewall structure is compared with images recorded by a high speed camera. Good agreement between the simulation results and test data indicates that the coupled SPH–FE method can provide a very powerful tool in predicting the dynamic responses of aircraft structures in events of bird strike.     

国际空间站测控通信系统研究

测控通信系统是国际空间站的重要组成部分,可靠的测控通信系统是确保空间站长期稳定在轨运行的基础。对国际空间站测控通信系统进行了较为深入的研究,介绍了国际空间站测控通信系统的组成,梳理了国际空间站中继S系统、中继Ku系统、空空通信系统的链路特性与工作方式,并总结归纳了国际空间站测控通信系统多手段备份、采用高性能编码等特点,以及对我国的启示,能够为我国测控通信系统的发展提供借鉴与参考。     

基于任意两点试验信息的寿命分散系数法

在试验数据缺失无法获得中位寿命时,为避免偶然因素导致个别试验结果偏低而造成技术寿命偏低,浪费寿命的情况,提出了基于任意两点试验信息的寿命分散系数法.推导了基于对数正态分布小子样任意两点试验信息的寿命分散系数计算公式,计算了给定置信度下相应的寿命分散系数.算例表明:利用提出的方法及相应寿命分散系数,得到的技术寿命与基于中位寿命获得的技术寿命结果接近,方法合理.最后给出了该方法的适用范围.      

基于在高原机场降落的喷气运输机QAR数据的飞行特性分析(英文)

Flight data of a twin-jet transport aircraft in revenue flight are analyzed for potential safety problems.Data from the quick access recorder (QAR) are first filtered through the kinematic compatibilit...     

基于Bayes理论的多源可靠性数据融合方法应用研究

对Bayes方法在多源可靠性数据融合中的应用进行了分析。将Bootstrap方法和随机抽样法应用于确定不同先验信息下的先验分布或先验分布中的超参数。论证了采用线性加权进行多源先验分布融合的合理性,并提出了将样本的边缘分布作为该方法中确定权重的一个衡量尺度。最后,采用上述方法对某飞机组件的寿命进行了统计推断。     

基于FlightGear的飞行导航数据可视化仿真研究

飞行器的飞行导航数据显示是控制其飞行轨迹不可缺少的一部分,针对飞行导航数据可视化仿真分析的需求,本文讨论了基于FlightGear软件的飞行导航数据可视化的实现方法。首先分析了FlightGear软件的特点及其相关组件的功能;之后,在导航系统工作基本原理的基础上,研究了导航数据三维可视化显示的可行性;最后针对FlightGear软件的特点以及与外部数据的传输方式,设计了导航数据可视化显示方案,实现了对飞行导航数据的三维可视化显示,达到人机交互的效果。     

高码率导航电文引起的跟踪环路失锁及其解决方法

卫星信号的多普勒频移会引起导航数据跳变点在1ms中频采样数据中的相对位置发生滑动,当跳变点处于采样数据段的中间位置时,相关器输出接近于零,造成环路失锁。本文在详细分析这一问题的基础上,针对“北斗II”信号提出了一种改进的环路跟踪方法。新方法通过在连续的两段1ms数据中找出不包含数据位跳变点的数据段,将该段数据的鉴相结果用于2ms环路更新。仿真和GNSS模拟器的实验验证了该方法的有效性。