From the actual perspective of working principle of localizer beacon subsystem of Instrument Landing System (ILS), consideration of the distance information from localizer antenna to field monitor antenna and wide ape...From the actual perspective of working principle of localizer beacon subsystem of Instrument Landing System (ILS), consideration of the distance information from localizer antenna to field monitor antenna and wide aperture effect of localizer antenna, broke through the limitation of signals synthesized only far-field (FF), established the near-field (NF) model. The three-dimensional mathematical model of localizer beacon was designed, and the signals at both near-field and far-field were analyzed qualitatively. At the environment of Antenna Fault as well as Antenna Distribution Unit (ADU) phase shifter simulation, the characteristics of near-field and far-field were also compared. The simulation results showed that the model met the requirement of theory of localizer beacon, and the gap between two models was so evident, which resulted from the broken geometric symmetry in NF area. The model could provide valuable theoretical basis for performance evaluation and maintenance of the ILS, and meanwhile, provide reference for the further analysis of localizer beacon.展开更多
文摘From the actual perspective of working principle of localizer beacon subsystem of Instrument Landing System (ILS), consideration of the distance information from localizer antenna to field monitor antenna and wide aperture effect of localizer antenna, broke through the limitation of signals synthesized only far-field (FF), established the near-field (NF) model. The three-dimensional mathematical model of localizer beacon was designed, and the signals at both near-field and far-field were analyzed qualitatively. At the environment of Antenna Fault as well as Antenna Distribution Unit (ADU) phase shifter simulation, the characteristics of near-field and far-field were also compared. The simulation results showed that the model met the requirement of theory of localizer beacon, and the gap between two models was so evident, which resulted from the broken geometric symmetry in NF area. The model could provide valuable theoretical basis for performance evaluation and maintenance of the ILS, and meanwhile, provide reference for the further analysis of localizer beacon.
文摘面向未来5G和卫星网构成的空地高通量互联场景,为实现飞机着陆风险提前预警.首先基于统计与模型,建立了一套以多源运行实时数据为主,融合历史统计和专家知识的着陆预警体系;然后,针对现有研究计算结果滞后问题,先通过对ARJ21飞机着陆过程快速存取记录器(QAR)数据的聚类分析,将飞行员着陆操作模式分为4类,进而构建基于决策场理论的飞行员着陆操作模式预测模型,计算并讨论不同场景下、不同个性飞行员的着陆模式选择;在上述基础上,针对着陆过程的复杂性和不确定性,提出一种分层计算的置信规则库推理方法,融合定性与定量信息实现着陆动态风险评估和预警.最后,通过对“2020.10.16攀枝花跑道外接地事件”和“2010.8.2伊春空难”着陆过程的风险推理验证了预警方法的有效性,其中攀枝花事件提前预警时间可达13 s.
