飞机红外辐射及大气透过率计算方法

研究了飞机目标的红外辐射特性,以及红外辐射在大气中的辐射衰减特性.根据现有的理论基础以及飞机自身结构特性,将飞机的红外辐射源分为蒙皮、尾喷口和羽流3部分,并提出了3个辐射源在不同波段、不同角度下的红外辐射特性计算方法.根据红外辐射的大气传输特性,采用了不同波长、不同弹目距离下的大气透过率简易计算方法,并将其与Lowtran7进行比较.计算了飞机在不同波段下,经大气衰减后,最终到达红外探测器的辐射强度.     

2相多循环脉冲爆震发动机燃烧噪声辐射特性试验研究

对内径为60 mm的2相多循环脉冲爆震发动机燃烧噪声辐射特性,在其测量位置处和一定试验频率范围内进行了试验研究。经研究发现:在一定低频范围内,噪声辐射频谱由气流脉冲的基频(即爆震频率)和谐频组成;脉冲噪声是1个或多个持续时间小于1s的猝发声组成的噪声;距离发动机喷口方向越近,噪声的声压级越强;反之,噪声衰减的速度越快。     

Quasi-biennial oscillation signals in outgoing long-wave radiation of the equator

In the present paper, the authors use wavelet transform technique to study time-series of outgoing long-wave radiation (OLR) anomaly at the equator during 1979–2005. The results show that quasi-biennial oscillation (QBO) signals exist in the OLR variation and the QBO cycle has remarkable temporal variability in its amplitude and phase. The periodic length of the QBO fluctuation is about 2.2-year before 1986. After that time, the length mainly changes from about 2.4- to 2.6-year. Analyzing the anomaly data set of 850 MB trade wind index (TWI) at west Pacific during this period, we have found that the obvious time-variations characteristics of the QBO cycle also exist in the TWI change at west Pacific and are in good consistence with that of the OLR change. The quasi-biennial fluctuation of the TWI change can explain that of the OLR change to a large extent.     

蒙皮热辐射特性对平流层浮空器氦气温度影响

分析了平流层球形超压浮空器在运行高度所受的各种环境辐射,研究浮空器处于热平衡状态时辐射传热、对流换热的作用规律,建立了浮空器的热平衡模型,分析太阳辐射、地面反照、地面辐射等环境辐照因素对浮空器全天各个时刻蒙皮材料和内部氦气平均温度影响,对比了吸收率、发射率和吸收发射比等辐射参数对浮空器热性能的影响.分析结果表明:具有低吸收发射比的蒙皮材料具有较好的热控效果;对于吸收发射比相同的蒙皮材料,具备低吸收率特性的蒙皮材料热控效果更为明显,更适用于长航时平流层超压浮空器.分析结果对浮空器蒙皮材料选择和总体设计具有指导意义.     

空间粒子辐射监测器用模拟信号源的实现

空间粒子辐射监测器需要有模拟信号源在其生产和测试、试验阶段对其进行电性能检测,并随其辗转于各测试场地。使用进口模拟信号源存在操作复杂、设备笨重及只有单路输出等问题,因此需要设计一种专用模拟信号源。根据空间粒子辐射监测器的要求自行研制的模拟信号源有多路模拟信号输出,且各路信号幅度可独立调节,并采用内部电源供电。经过测试验证,该模拟信号源可作为空间粒子辐射监测器的配套设备使用,性能优于原进口模拟信号源,其电路设计亦可为相关设备提供参考。     

新型航天器抗辐射加固技术的研究重点

未来新型航天器在研制模式、设计技术、元器件及材料等方面与以往卫星相比将有较大变化,从而对抗辐射加固技术提出新的要求。因此,抗辐射加固技术的研究重点须在以往研究基础上进行调整。文章从航天器总体角度,对新型航天器抗辐射加固技术的研究重点进行探讨。     

空间重离子辐照效应评述

文章对生物、半导体、光学材料、金属、聚合物的空间重离子辐照效应的研究工作进行了评述,也阐明了深入开展重离子空间环境模型以及重离子辐照效应与演化规律的研究具有重要意义。研究表明空间环境中重离子的含量虽少,但由于其高的电离能力和穿透力,对生物、半导体、光学材料、金属、聚合物等会产生各种辐射损伤效应,导致卫星信号故障、光学器件失效、金属与聚合物性能及形貌改变,甚至影响航天员的生命安全。     

Analysis of solar spike events by means of symbolic dynamics methods

We have searched for interrelations of spikes emitted simultaneously at different frequencies during the impulsive phase of flare events (Fig.1). As the spikes are related to the flare energy release and are interpreted as emissions that originate at different sites having different magnetic field strengths, any relation in frequency is interpretated as a relation in space. Quantities of symbolic dynamics, such as mutual information, Shannon information and algorithmic complexity are appropriate to characterize such spatiotemporal patterns, whereas the popular estimate of fractal dimensions can be applied to low-dimensional systems only.The goal is to decide between two possible types of fragmentation depending on the energy release and emission processes, which we callglobal andlocal organization. In the global organization the whole region becomes supercritical, and the energy is released in independent, small regions. The alternative local scenario requires a trigger that spreads from initial localized events and ignites nearby regions.Mutual information which is a generalization of correlation indicates a relation in frequency beyond the bandwidth of individual spikes. The scans in the spectrograms with large mutual information also show a low level of Shannon information and algorithmic complexity, indicating that the simultaneous appearance of spikes at other frequencies is not a completely stochastic phenomenon (white noise). It may be caused by a nonlinear deterministic system or by a Markov process. By means of mutual information we find a memory over frequency intervals up to 60 MHz (Fig. 2). Shannon information and algorithmic complexity, however, describe spike events as a whole, i.e. a global source region. A global organization is also apparent in quasi-periodic changes of the Shannon information and algorithmic complexity in the range of 2–8 seconds (Fig. 3).This findings is compatible with a scenario of local organization in which the information of one spike event spreads spatially and hence triggers further spike events at different places. The region is not an ensemble of independently flashing sources, each representing a system that cascades in energy after an initial trigger. On the contrary, there is a causal connection between the sources at any time.The analysis of four spike events suggests that the simultaneous appearance of spikes is not stochastically independent but a process in which spikes at nearby locations are simultaneously triggered by a common exciter.We have shown in the case in the case of spikes that quantities from nonlinear dynamics used in this paper are helpful in detecting structural properties of complex spatio-temporal patterns. This approach seems to be promising also for several other astrophysical applications.