Effect of the seed perturbation amplitude on the equatorial spread F initiation during solar minimum

The contribution of gravity wave (GW) to the initiation/development of spread F during a solar minimum year was investigated through the comparison of the observed precursory parameters and characteristics of the corresponding equatorial spread F (ESF) events. The ionospheric parameters were recorded at the magnetic equatorial station Sao Luis (2.3°S, 44°W, dip latitude 2°S) during March and October 2010. These data were used to estimate the influence of the relative gravity wave amplitude and the ambient ionospheric condition on the diurnal variation of the spread F initiation. The vertical velocity drift indicated a clear control and defines the threshold for the seasonal variability of the ESF occurrence. However, it was insufficient to solely determine or predict the day to day variation of ESF occurrence. Thus, few days with contrasting ambient ionospheric condition and magnitude of GW amplitude were analysed in order to investigate the role of the different precursory factors in the observed diurnal variation of the plasma irregularity development. The density scale length and gravity wave amplitude were shown to immensely contribute to the linear instability growth rate, especially during the days with a low post-sunset rise. Thus, the experimental observations have demonstrated the strong inter-dependence between the precursory factors and they have also highlighted the probable control of the ESF morphology.     

贴地飞行时旋翼空气动力学实验研究

 本文对贴地飞行时的旋翼进行了流场显示和桨盘处下洗速度测量的实验研究。揭示并研究了环流和地面涡现象及其对旋翼平面下洗速度分布的影响,指出了旋翼贴地飞行时拉力、力矩等剧烈变化的原因。     

Evaluation of airborne data link communication

An experimental prototype of a cockpit data link communication interface (modified Navigation Display (ND) and Multi-purpose Control and Display Unit (MCDU)) was developed and tested in an Airbus A340 Full Flight Simulator. 8 crews (16 professional pilots) performed simulator flights in a mixed voice and data link scenario. After each experiment video recordings were presented to the pilots and they were asked to estimate subjective strain (NASA task load index) and situational aspects retrospectively. Results show an increase in subjective strain and a decrease of ‘feeling of sovereignty’ and situation awareness under data link conditions. The effect is similar to the one caused by higher workload.     

瞬态时域数据合成冲击响应谱算法研究

某液体火箭发动机的部件采用振动台进行模拟冲击环境试验,冲击控制谱的冲击时域波形由软件采用基本波形合成,基本波形有正弦波、合成小波、Chirp波形,而国内常用正弦波合成冲击谱进行冲击环境试验。给出了瞬态冲击数据合成法的算法过程,提取某液体火箭发动机试车过程中的冲击时域数据来合成冲击控制谱的冲击时域波形,计算结果表明算法有效,所合成的冲击时域数据能够满足冲击响应谱的精度要求。     

一种基于计算几何控制无量纲参数的叶片造型方法

应用目前先进的自由曲线理论,开发了一种新的叶片造型方法——B样条控制中线角叶型(BMAA)方法。分别选取准均匀B样条和贝塞尔曲线,实现了对叶型中线和厚度的方便、灵活控制;同时综合考虑方便性与实用性,选取四点控制参数进行设计。分别利用BMAA方法与原有定制叶型、任意中线方法,对某单级压气机进行设计,结果表明:对于超/跨声叶片设计,BMAA方法设计的叶片性能略优于定制叶型;与任意中线叶型达到的性能相当,但叶型控制便捷性和叶型光滑性优于任意中线叶型。     

任务计划地面站编队数据加载方法研究

随着航空电子系统不断发展,任务计划地面站作为航电系统的一个场站保障设备,为飞行前数据的组织、任务数据加载、飞行后记录数据的管理传输和视频/音频的回放提供了一种快速、准确、规范和安全的技术手段。为适应航空电子系统多机编队任务参数地面加载需求,确保多个任务计划中加载数据的准确性,降低用户对编队内几架甚至十几架飞机制作任务参数的难度,本文提出了合理有效的编队数据加载方案,给用户的使用带来了极大的方便。     

冲击试验条件的转换方法及其应用

对冲击试验条件的转换方法进行了研究。利用从频域响应谱到时域激励信号的不唯一性,由小波合成法构造足够数量满足响应谱试验规范的时域激励信号,并施加到单机的有限元模型。用MSC．NASTRAN软件仿真计算单机中元器件安装位置处的响应。统计响应样本,获得在一定概率条件下元器件可能出现的响应峰值。将该峰值作为元器件冲击试验的半正弦波幅值,并以元器件产生最大响应的激励持续时间作为元器件冲击试验的作用时间参数,实现冲击试验条件的转换。给出了一个单机模型的冲击试验条件转换实例。     

基于多种并发机制的卫星电子设备地面测试软件设计方法

在卫星电子设备测试系统中,地面测试软件不仅要访问测试系统硬件,而且需要与用户直接交互,并完成测试数据的存储和管理,并发处理能力是测试系统可靠和正确的关键,传统软件设计采用的串行策略无法适应卫星地面测试软件中的并发处理需求.为解决上述问题,提出多线程、消息机制、共享缓冲区、P-V操作4种并发机制相结合进行程序设计的方法.实际应用表明采用这种基于多种并发机制的程序设计方法能可靠实现卫星地面测试软件,有效解决了软件开发中的并行性问题.     

基于方波信号的半全局极值搜索算法

针对半全局极值搜索算法,采用正弦信号作为激励信号时,幅值自适应律初始值选取严格、输出存在颤振的问题,提出了采用方波信号作为激励信号。利用平均化方法证明了激励信号选取较小的初始值即可使目标函数收敛到全局极值,同时减弱了输出颤振;采用正弦和方波信号作为激励信号进行仿真对比,说明方波信号可以提高算法的半全局收敛性,有效减弱输出颤振。