论现有远地点发动机用于新航天飞行器的有关问题

为了使正进入鉴定阶段的远地点发动机(TE-M-616)用于广播试验卫星,本文介绍了该新航天飞行器对远地点发动机的各系统及分系统提出的要求。由于加拿大通讯技术卫星和广播试验卫星对远地点发动机在环境和性能要求上有所不同,为了解决此问题,必须使远地点发动机经受住最恶劣的环境。喷管设计以及远地点发动机与航天器的对接都利用现有设计结构。根据对远地点发动机分析的结果,已经表明,若保持安全系数不变,只需要对现在进行的试验计划做一些修改和补充。另一方面,对于航天器提出的技术条件必须进一步审核,以便使新航天飞行器设计有最大可能利用现有的远地点发动机。     

一种大变形多空间域连续体结构拓扑优化方法

针对大变形非线性结构拓扑优化问题,提出了基于混合细胞自动机(HCA, Hybrid Cellular Automata)多空间域连续体结构拓扑优化方法;采用密度法,建立了单元相对密度表示的材料弹-塑性模型;以单元相对密度和应变能作为细胞自动机(CA,Cellular Automata)的状态信息,利用CA局部控制规则,修改相对密度,迭代实现各设计空间域应变能均匀分布;设计了多空间域拓扑优化HCA算法,采取多个对象同时耦合优化迭代,各自收敛策略,解决了多空间域优化迭代算法收敛稳定性问题;最后,以汽车保险杆结构横梁和支撑等两个设计空间为例,施加大变形动态载荷作用,对提出的多空间结构优化算法进行了验证,优化后结构有效地降低了碰撞作用力峰值达54％,提高了结构安全性.     

DS/FH混合扩频快速捕获技术的研究

在DSFFH混合扩频通信系统中,快速捕获是一个非常关键的技术。通过采用快速扫描和等待式相结合的方法用来实现跳频信号的快速捕获,利用神经网络技术实现直扩信号的快速捕获,通过这2种方式,就可实现DSFFH混合扩频的快速捕获。     

The Physical Foundation of Forecasting Disturbances in the Geospace From Solar Disk Characteristics

The five main types of antisunward propagating energetic fluxes (particles and emission) may be thought of as well established to date, the effects of which lead to a particilar character of disturbance in the near-terrestrial environment (the Earth's magnetosphere, ionosphere and atmosphere). The strongest global restructuring of the magnetosphere and ionosphere is caused by fluxes of relatively dense n of 1-70 cm-3 at the Earth's orbit) Solar Wind (SW) quasi-neutral, low-energy (E ＜ 10 keV) plasma which cause magnetospheric and ionospheric storms lasting 24 hours or longer. For that reason, main attention is given to their study at the initial stage of research. The physical essence of the method of predicting disturbances in the near-terrestrial space environment, the amplitude of which can be expressed in, for example, the Kp index units, involves:(1) identifying all the most geo-effective SW streams of type, (2) determing their sources on the solar disk,and (3) quantifying the correlations between the characteristics of their solar sources with a maximum value of the Kp-index that is caused by the concerned type of SW stream. Semi-phenomenological relations have been obtained, which relate parameters of type SW stream sources to characteristics of geomagnetic storms:storm commencement, the time at which the storm intensity reaches its maximum values, the storm duration,as well as to the storm amplitude expressed in terms of geomagnetic indeces.      

Study of the Enhancement Events of Relativistic Electron at the Geosynchronous Orbit

The high flux of energetic electron on geostationary orbit can induce many kinds of malfunction of the satellite there, within which the bulk-charging is the most significant that several broadcast satellite failures were confirmed to be due to this effect. The electron flux on geostationary orbit varies in a large range even up to three orders accompanied the passage of interplanetary magnetic cloud and the following geomagnetic disturbances. Upon the investigation of electron flux enhancement events, two types of events were partitioned as recurrent events and random ones. Both of the two kinds of events relate to the interplanetary conditions such as solar wind parameters, IMF etc and their evolution characters as well. As for the recurrent events, we found that, (1) all of the events exhibits periodic recurrence about 27 days, (2) significant increase of electron flux relates to interplanetary index and characters of their distribution, (3) the electron flux also has relation to solar activity index. An artificial neural network was constructed to estimate the flux I day ahead. The random electron flux enhancement events are rare and present different distribution figures to the recurrent ones. The figure of the random events and the conditions of their occurrence is also discussed in this paper.      

电推进系统为何会扰乱MRO行业

<正>随着电推进系统研发工作取得持续的进展,航空维修领域非常有必要提前了解电推进的发展现状和未来走势,尤其是发动机维修售后市场参与者需要尽早参与电动飞机设计过程,以便获得对飞机维修性的最直接的实践反馈,并且及早建立与之相适应的维修能力、维修设施、维修模式和维修培训系统等。     

先进的模块化跟踪器：一个实时的电视跟踪器

本文叙述先进的模块化跟踪器(AMT)，一个可以实时跟踪诸如运载火箭、卫星等目标的电视跟踪器。AMT是美国空军菲力浦实验室为捕获、跟踪、瞄准(ATP)实验而自行开发的一个项目。它采用了DATACUBE公司并行流水式图象处理硬件和图象流软件。目前的AMT版本使用：DATACUBE公司的MAXVIDEO-20、MAXSCAN和MLA860板。AMT可同时对二个不同的视频输入进行行星、边缘和相关跟踪，并可实时进行输入图象的视频转换、实时直方图计算及图象的处理。AMT具有自动捕获跟踪目标，自动调节阈值和波门大小的能力，它可用于任何地基、空基和天基等需要自动跟踪的应用场合。     

棒状推进剂的侵蚀燃烧模型及其测定方法

大弹径的无缝单孔棒状推进剂的侵蚀燃烧效应,对其内弹道性能有显著的影响。为研究其侵蚀燃烧现象,提出了一种着重强调湍流与燃烧相互作用的易行模型。实验台上用的是一种设计成大肉厚的(约1.0cm)、中孔圆筒形药柱。药柱燃面的瞬时位置,用实时X射线照相术来测定。X射线照片表明,在强横向流作用下,实测的NOSOL—363棒状推进剂的瞬时燃速,明显地高于它的线燃速(4—32倍)。证明了这种测试方法的有效性。     

热塑塑料在宇航结构中的应用

介绍热塑塑料及其复合物的种类和在宇航领域中的应用;其潜力能否充分挖掘取决于是否能经济有效地设计和制造这些材料.正涌现出的热塑塑料在竞争激烈的工程领域有可能满足宇航应用的要求.添加合适的纤维加强物使中空成微球状来减小密度和个电特性,“塑性”材料就能广泛应用,热塑塑料当然是其中之一.但热塑塑料也不会完全取代热固性材料,它们只是相互取长补短.