考虑预防性维修的离散时间单部件系统的可用度模型

对预防性维修的单部件离散可修系统,假定系统寿命、修复性维修和预防性维修的修复时间均遵从离散的一般分布,修复为完全修复,利用概率分析的方法详细讨论了系统正常、修复性维修和预防性维修3个状态之间的转移关系,在此基础上建立了该系统的瞬态可用度模型,最后进行了仿真校验。结果表明,预防性维修对系统瞬时可用度的影响较大,特别是当系统故障率为单调递增时,合理的预防性维修将起到提高系统可用度的效果,该模型能较好地反映工程中的情况,具有良好的工程应用前景,可以帮助维修人员更好地完成工程系统的保障和维修。     

机身气动载荷计算

介绍了机身气动载荷垂直平面内和水平平面内的几种典型分布形式,并推导出各分布形式下的计算公式。     

数据链技术的发展及其在空面导弹中的应用

现代战争样式由平台中心战演变成信息中心战,数据链技术在教练机训练装备和导弹武器系统中起到了重要作用。从分析国外武器装备系统的数据链技术发展情况入手,浅析我国武器数据链新技术在空面武器中的初步应用,研究了数据链网络容量/质量与效能关系,提出了发展空面武器的数据链应用时需先明确数据链的战术功能。分析表明:空面导弹互通技术的应用需要有相匹配的网络体系保障,以及多军种联合作战对数据链信息兼容。     

引气在超声进气道中的研究现状及应用探讨

激波/附面层干扰现象的存在严重影响超声进气道的气动性能和稳定工作范围。经过50多年的研究和实践,引气作为主动控制的有效方式,现已广泛用于超声进气道的流动控制。从附面层控制引气和稳定性控制引气两个方面对引气在超声进气道中的研究应用进行了回顾。阐述并总结了引气对激波/附面层干扰的控制机理及其对超声进气道流动稳定性的影响,展望了高超声速进气道中引气技术的发展趋势。     

基于光纤传感技术的着靶点测量系统设计

为检验武器系统的制导精度,必须对制导武器命中靶标的相对位置即脱靶量进行测量。针对靶船着靶点测量的需求,提出基于光纤传感技术的测量方案。在分析光纤传感器测量原理的基础上,通过光纤传感器网格、光源发射装置、信息采集、数据接收处理等分系统的设计,实现对靶船着靶点的高精度实时测量。通过对系统工程实现及关键技术问题的研究,表明该系统的技术可行性和工程可实现性,并可推广应用于其它靶标系统。     

Statistical seismo-ionospheric precursors of M7.0+ earthquakes in Circum-Pacific seismic belt by GPS TEC measurements

The Circum-Pacific seismic belt is the region heavily affected by earthquakes in the world. The relationship between earthquake (e.g., the geographic location, occurrence time, magnitude, and focal depth) and ionospheric anomalies in the belt was investigated using 100 M7.0+ earthquakes during 2006–2015. The ground-based GPS measurements and global ionosphere map (GIM) data were used for the analyses of the ionospheric variations preceding the earthquakes. The results indicated that the occurrence rate of total electron content (TEC) anomalies was proportional to the magnitude and inversely proportional to the focal depth to a certain degree, and the occurrence frequency of anomalies had a rising trend with the days getting close to the main shock. The occurrence rate of TEC anomalies in the Southern hemisphere was larger than that in the Northern hemisphere. Besides, the spatial characteristics of TEC anomalies showed that the anomalies in low-middle latitudes did not coincide with the epicenter, sometimes the anomalies were also observed in the corresponding conjugated region. However, the TEC anomalies in the high latitude usually appeared around the epicenter and within the seismogenic zone while no TEC anomalies appeared in the conjugated area. These results may have potential applications to the earthquake prediction in the Circum-Pacific seismic belt.     

低雷诺数涡轮内部流场分析

利用三维数值模拟手段研究涡轮内部流动.对比分析了不同飞行高度工作时涡轮内部流场结构的差异,以反映雷诺数的降低对流动结构和性能的影响.结果表明:在高空工作环境下,雷诺数下降近一个量级,负荷分布发生变化,叶片吸力面发生大范围分离,二次流以及径向掺混明显增强,由此导致涡轮性能恶化,效率急剧下降,这些因素在低雷诺数涡轮气动设计中需给予更多的关注.同时指出,负荷分布形式的选择对低雷诺数涡轮设计有重要意义.     

Observations of Vertical Reflections from the Topside Martian Ionosphere

The Martian ionosphere has for the first time been probed by a low frequency topside radio wave sounder experiment (MARSIS) (Gurnett et al., 2005). The density profiles in the Martian ionosphere have for the first time been observed for solar zenith angles less than 48 degrees. The sounder spectrograms typically have a single trace of echoes, which are controlled by reflections from the ionosphere in the direction of nadir. With the local density at the spacecraft derived from the sounder measurements and using the lamination technique the spectrograms are inverted to electron density profiles. The measurements yield electron density profiles from the sub-solar region to past the terminator. The maximum density varies in time with the solar rotation period, indicating control of the densities by solar ionizing radiation. Electron density increases associated with solar flares were observed. The maximum electron density varies with solar zenith angle as predicted by theory. The altitude profile of electron densities between the maximum density and about 170m altitude is well approximated by a classic Chapman layer. The neutral scale height is close to 10 to 13 km. At altitudes above 180 km the densities deviate from and are larger than inferred by the Chapman layer. At altitudes above the exobase the density decrease was approximated by an exponential function with scale heights between 24 and 65 km. The densities in the top side ionosphere above the exobase tends to be larger than the densities extrapolated from the Chapman layer fitted to the measurements at lower altitudes, implying more efficient upward diffusion above the collision dominated photo equilibrium region.     

我国民航维修业的现状与挑战

中国民航运输业的快速发展,推动了民航维修业的成长与变革。本文回顾了飞机维修业的发展历程,分析了基于国情的现状特点。展望了维修业的发展趋势,包括布局向中西部发展,迎接通航市场,面临机型更新换代的挑战,企业维修资质认可性增强,大型企业进行升级转型,发展“客改货”等业务,涉足设计领域等。并重点关注了人才培养的问题,指明了高校、企业、培训机构在人才培养上的问题和改进方向。     

天翼1无人机电动化改造可行性分析

电动飞机正在国内外通用航空领域蓬勃发展,并影响着未来航空的发展方向。利用电推进技术对无人机进行电动化改造,能大大提高无人机的安全性、可靠性和维修性,降低使用成本。以天翼1无人机为电动化改造对象,提出了电动化改造方案,详细计算分析了电推进系统中电动机和锂电池组的主要参数,并从无人机的重量重心、性能以及电推进系统的安装方式等方面分析了改造的可行性。分析结果表明,天翼1无人机电动化改造基本可行;并提出了后续改造实施中需注意的问题。