基于多流路体积力模型的翼身融合布局飞机计算方法

针对翼身融合布局(BWB)飞机分布式系统一体化研究方法存在计算资源耗费巨大的问题,发展基于多流路体积力的飞机分布式系统一体化计算方法。从沿流线的体积力模型出发,将压气机对气流的作用力用沿流线的源项场代替。将单流路的计算模型加以扩展,综合考虑分布式推进系统与BWB的耦合影响,在分布式推进系统的压缩系统所在区域添加体积力源项,建立多流路体积力计算模型。将其应用于某大型BWB飞机进行一体化数值仿真。结果显示:相较于传统的全周定常数值模拟方法,采用多流路的体积力模型能够在保证一定计算精度的条件下提高至少10倍的计算效率。     

ARINC 653分区实时系统的主时间框架设计

综合模块化航空电子系统中的ARINC 653标准规定系统采用分区内调度和分区间调度双层调度机制。根据标准,分区内的调度由分区设计者指定,分区之间则按照静态的主时间框架进行调度。如何基于多个分区应用设计用于分区间调度的主时间框架是系统集成阶段需要解决的问题。首先利用可调度分析导出了分区的有界延迟模型参数,进一步将该参数转化为分区的调度参数用于分区间调度。然后进行分区间调度生成主时间框架,提出了最少窗口数目匹配-最佳匹配（MFBF）算法用于减少分区窗口的切换次数。提出的从分区参数推导到分区间调度流程能够基于若干分区应用生成ARINC 653系统的主时间框架。实验结果表明:时间窗口优化算法能有效减少分区窗口切换次数。      

航天器任务规划中资源约束的可分配处理方法

面对深空探测过程中环境的不确定性和扰动,航天器需要利用任务规划技术实现自主控制。航天器应用规划算法时,需要考虑到执行活动时满足的时间约束和资源约束。通过分析资源约束之间的关系,提出了可重复资源在规划执行时的可分配处理方法,和判断资源变量是否满足的可分配性条件。通过航天器仿真算例,验证了可重复资源的可分配处理方法在规划执行时的有效性。     

Review of in-space assembly technologies

With the rapid development of space technology and the increasing demand for space missions, the traditional spacecraft manufacturing, deployment and launch methods have been unable to meet existing needs. In-space assembly (ISA) technologies can effectively adapt to the assembly of large space structures, improve spacecraft performance, and reduce operating costs. In this paper, the development and technologies for ISA are reviewed. ISA is classified from multiple angles, and the research status of ISA is shown clearly through the visual mapping knowledge domain. Then the development status of autonomous robot assembly in the United States, Europe, Japan, Canada and China is reviewed. Furthermore, the key technologies of ISA are analyzed from three aspects: assembly structure design, robot technologies and integrated management technologies. ISA technologies are still facing major challenges and need to be further explored to promote future development. Finally, future development trends and potential applications of ISA are given, which show that ISA will play a vital role in human space exploration in the future.     

On the practical exploitation of perturbative effects in low Earth orbit for space debris mitigation

This paper presents the results of a numerical evaluation of the natural lifetime reduction in low Earth orbit, due to dynamical perturbations. The study considers two values for the area-to-mass ratio, a nominal ratio which resembles a typical value of spacecraft in orbit today, and an enhanced ratio which covers the surface augmentation. The results were obtained with two orbit propagators, one of a semi-analytical nature and the second one using non-averaged equations of motion. The simulations for both propagators were set up similarly to allow comparison. They both use the solar radiation pressure and the secular terms of the geopotential ($J_2,J_4$ and $J_6$). The atmospheric drag was turned on and off in both propagators to alternatively study the eccentricity build up and the residual lifetime. The non-averaging case also covers a validation with the full 6?×?6 geopotential. The results confirm the findings in previous publications, that is, the possibility for de-orbiting from altitudes above the residual atmosphere if a solar sail is deployed at the end-of-life, due to the combined effect of solar radiation pressure and the oblateness of the Earth. At near polar inclinations, shadowing effects can be exploited to the same end. The results obtained with the full, non-averaging propagator revealed additional de-orbiting corridors associated with solar radiation pressure which were not found by previous work on space debris mitigation. The results of both tools are compared for specific initial conditions. For nominal values of area-to-mass ratio, instead, it is confirmed that this resonance effect is negligible.The paper then puts the findings in the perspective of the current satellite catalogue. It identifies space missions which are currently close to a resonance corridor and shows the orbit evolution within the resonances with a significantly shorter residual orbital lifetime. The paper finishes with a discussion on the exploitation of these effects with regards to the long-term simulation of the space debris environment and a flux and collision probability comparison.     

多约束条件下月球南极探测返回窗口设计

针对月球南极探测任务,综合考虑中国地基深空测控系统现状、月球南极地区光照及地球再入终端等约束条件,利用月球反垂点概念,提出一种从环月轨道出发的三级返回窗口搜索策略.其次,提出一种改进多圆锥截线法,将月球非球形摄动加入到区间的轨道外推中,基于二级返回窗口对返回轨道进行了初步设计.给出以月球南极地区Shackleton撞击坑边缘一点为假定落点,于2020年自月球南极地区返回的仿真算例.仿真结果表明：一方面,窗口搜索方法可以有效解决多约束条件下的月球南极返回窗口设计问题;另一方面,改进多圆锥截线法作为一种初始轨道设计方法,可以有效减少再入误差,同时为后续高精度轨道积分提供良好初值.     

Effects of dust polarity and nonextensive electrons on the dust-ion acoustic solitons and double layers in earth atmosphere

Propagation of dustion acoustic solitary waves (DIASWs) and double layers is discussed in earth atmosphere, using the Sagdeev potential method. The best model for distribution function of electrons in earth atmosphere is found by fitting available data on different distribution functions. The nonextensive function with parameter $q=0.58$ provides the best fit on observations. Thus we analyze the propagation of localized waves in an unmagnetized plasma containing nonextensive electrons, inertial ions, and negatively/positively charged stationary dust. It is found that both compressive and rarefactive solitons as well as double layers exist depending on the sign (and the value) of dust polarity. Characters of propagated waves are described using the presented model.     

一种低信噪比条件下的深空探测载波捕获算法

针对深空测控通信系统中,接收端收到的载波信号信噪比极低的特点,提出了一种时分复用的二维FFT载波捕获方法。该方法在降低资源消耗的情况下,能够有效实现低信噪比条件下的载波捕获。仿真实验表明,使用此种方法,能够在载噪比为17 dBHz的条件下,完成对载波频偏最大为100 kHz、载波频率变化率最大为100 Hz/s的载波信号的快速捕获,是一种兼顾性能和工程应用的捕获方法。     

民用飞机综合模块化航电系统资源状态监控技术研究

随着处理器和机载嵌入式实时分区操作系统等相关技术的不断升级换代,IMA系统功能的集成度也越来越高,高集成度增加了系统资源分配的难度,需要通过对系统资源状态进行实时监控和分析进而不断优化系统配置。首先对IMA系统的分区特性进行了深入研究,基于探针插桩监控数据采集技术,提出了一种系统行为和时间资源状态监控的策略。研究了数据监控采集系统的软件架构,在此基础上设计和实现了系统行为监视器和时间资源监视器,并在某民机重点预研课题中进行了应用验证。结果表明,能够有效帮助应用开发者和系统综合者直观分析系统时间性能瓶颈,优化资源配置方案,实现计算资源的负载均衡。对IMA系统资源状态监控及资源配置优化具有一定的指导意义和实用价值。     

陆地卫星地面接收站微波系统扩充方案

讨论了为接收Landsat-6而扩充的陆地卫星地面接收站微波系统方案。该工作完成后,不仅能实现对Landsat-5、Landsat-6、SPOT 卫星的兼容,而且配上相应的解调器也能接收ERS-1、JERS-1及中国即将发射的资源卫星及其它工作在8025～8400MHz 的任何卫星的发射数据。