天基星空背景观测覆盖范围计算方法研究

针对日趋复杂的空间环境，天基观测由于其分布灵活和全天候观测的特性受到越来越多的关注，该类问题为典型的星空背景观测（above-the-horizon，ATH）问题。基于分段积分思想，提出了一种ATH观测三维空间覆盖范围的计算方法，涵盖了该问题所有可能的10种积分形式，适用于因观测约束参数不同取值而形成的任意几何构型场景。不仅在二维平面覆盖问题上与现有方法进行了比较并验证，还首次解决了ATH在三维空间中覆盖体积的定量解析计算难题。仿真结果表明，平面和空间覆盖最大化所对应的最优观测轨道高度存在明显差异，空间覆盖计算模型能更为准确有效地表示卫星覆盖性能，同时能为星座优化设计提供参考。     

基于语义的仿真网格模型资源发现技术

针对现有网格资源管理中间件缺乏对仿真模型资源语义层次的描述和发现匹配这一问题,引入本体概念,定义了仿真模型描述本体,实现了对仿真模型的语义描述;提出了基于本体推理的仿真模型语义匹配算法,将仿真模型语义匹配的量化程度映射到了 上的连续值域,并且支持仿真模型输入/输出的组合匹配;将研究结果应用于仿真网格的仿真模型匹配发现服务的实现中,通过典型的应用实例,有效地验证了提出的仿真模型描述本体和语义匹配算法.      

直升机减振的旋翼桨叶优化设计研究综述

围绕降低直升机振动水平的旋翼桨叶减振优化设计,对国内外这方面研究进展情况作了综述;着重讨论了降低旋翼激振力减振优化设计分析中的几个主要问题,包括桨叶减振优化设计途径与目标,桨叶优化设计中的分析模型,优化设计方法及灵敏度分析技术,以及桨叶优化减振设计研究的最新发展方向和需进一步研究的问题等.      

New atomic data for the FeXII coronal ion

Various FeXII spectroscopic lines in the UV and EUV range have been proved to be ideal diagnostic tools for measuring electron temperature, density and iron abundance in the solar corona. In the framework of the “IRON PROJECT” we have provided improved theoretical calculations of the atomic data required to analyse the intensity of these lines and to apply the results to SOHO (Solar Heliospheric Observatory) observations. Extensive configuration interaction and relativistic effects have been allowed for in the atomic structure computations which have provided energy levels and an extensive set of radiative data. The e-FeXII collisional problem has been tackled with the multichannel R-matrix method, a close-coupling calculation for the determination of electron impact collision strengths. Final results are presented for FeXII thermally averaged collision strengths, for fine-structure forbidden transitions within the ground configuration.     

基于改进遗传算法对小卫星星群任务规划研究

针对小卫星星群任务运行特点,建立小卫星星群多任务规划问题模型,提出了基于成像任务时间及任务均衡度的多指标优化函数.针对所建模型,采用改进型遗传算法,引入资源随机分配的解码策略及精英保留策略,保证了算法的全局收敛性,提高了算法的性能.通过仿真算例,验证了算法在解决小卫星星群多目标任务规划问题上的有效性.      

一种用于SGCMG奇异规避的CVP轨迹规划

采用单框架控制力矩陀螺(SGCMG)作为执行机构的小型敏捷卫星在姿态机动过程中存在着奇异问题.本文从SGCMG姿态控制系统整体出发，将奇异问题转化为状态约束的动态控制问题，基于控制变量参数化(CVP)方法，设计了一种用于SGCMG奇异规避的轨迹规划.该算法在实现小型敏捷卫星大角度姿态机动过程无奇异的基础上，将SGCMG框架角转速的最优轨迹通过CVP方法进行分段线性规划.这种规划策略对框架伺服系统的算法设计无复杂要求，仅需要简单的加减速控制，从而节约了星上资源.在轨迹规划实现过程中，考虑了工程实际中的约束条件，可以按照姿态机动任务要求规划出一条综合考虑能量资源和目标精度的最优轨迹.仿真结果表明：该算法实现了姿态参数轨迹和星体角速度轨迹的平缓变化，目标误差在1×10-3量级，星体在机动过程中运行稳定，SGCMG不会出现奇异现象.     

皮秒级时间间隔定标技术研究

传统的时间间隔产生和测量技术的不确定度只能到1 ns左右,无法满足高速测量需求。介绍了一种新的时间间隔定标技术,利用现有仪器解决了皮秒级时间间隔产生、校准的难题,将皮秒级时间间隔溯源到了时间频率的国防最高标准,实现了小至1 ps的皮秒级时间间隔准确定标技术。     

任意波形失真度的一种评价方法

鉴于失真度指标在评价波形总体质量方面具有的独特优势并获得广泛认可,在对任意波形失真度定义分析的基础上,提出一种使用波形非线性拟合方式进行任意波形失真度的评价方法.对于待评价的任意波形,首先通过模型平移,从时间维度上与被评价任意波形进行“相似拟合”,然后通过最小二乘拟合,在幅度上与被评价任意波形进行拟合,从而得到被评价任意波形的最佳拟合曲线,进而计算得到任意波形的失真度.实验结果显示,该方法具有较强的可行性与适应性,能够解决对于任意波形失真度的评价问题,并进而解决对任意波形以及任意波发生器的计量校准问题.      

Status of the NASA continuing investigation of catastrophic balloon failures

Since the beginning of the 1980's, the USA National Aeronautics and Space Administration (NASA) Balloon Program has been besieged with a continuing problem of catastrophic balloon failures. In 1983 NASA conducted an investigation to identify possible causes for the failures and to determine the necessary corrective action(s) to prevent further occurrence of the problem. The investigation indicated the most probable cause of the failures was the balloon material. Subsequent corrective action(s) were taken to eliminate the problem by establishing a material acceptance criteria for balloon film. Although improvements have been noted in certain classes of balloons, the problem of catastrophic balloon failures continues. Efforts continue, to determine the cause(s) of the diminished performance of current balloons, including investigation of the microstructure of present and past balloon film, stress effects and simplified stress modeling including shape studies, and the equipment and procedures used in the manufacture of balloons. Most recently, a special team of experts has been assembled to aid in the investigation of the failure problems and the methods needed for a solution. The findings and status of the continuing investigation along with the future plans for the NASA program are presented.     

Engineering strategies for the design of plant nutrient delivery systems for use in space: approaches to countering microbiological contamination.

Microbiological contamination of crops within space-based plant growth research chambers has been postulated as a potentially significant problem. Microbial infestations; fouling of Nutrient Delivery System (NDS) fluid loops; and the formation of biofilms have been suggested as the most obvious and important manifestations of the problem. Strict sanitation and quarantine procedures will reduce, but not eliminate, microbial species introduced into plant growth systems in space habitats. Microorganisms transported into space most likely will occur as surface contaminants on spacecraft components, equipment, the crew, and plant-propagative materials. Illustrations of the potential magnitude of the microbiological contamination issue will be drawn from the literature and from documentation of laboratory and commercial field experience. Engineering strategies for limiting contamination and for the development of countermeasures will be described. Microbiological control technologies and NDS hardware will be discussed. Configurations appropriate for microgravity research facilities, as well as anticipated bio-regenerative life support system implementations, will be explored. An efficiently designed NDS, capable of adequately meeting the environmental needs of crop plants in space, is considered to be critical in both the research and operational domains. Recommended experiments, tests, and technology developments, structured to allow the development of prudent engineering solutions also will be presented.     

一种推进系统故障诊断反问题模型与算法

针对大型液体火箭推进系统故障诊断工作的需要, 建立了一种推进系统故障诊断反问题模型,并提出了基于遗传算法的反问题求解算法.在对故障诊断反问题的特点与困难及其求解方法研究的基础上,重点论述了基于遗传算法的反问题求解算法和基本过程.最后,给出了液体火箭推进系统故障诊断反问题求解的具体例子,表明所建立的推进系统故障诊断反问题模型及所提出的算法是合理有效的.      

Progress towards a new global foF2 model for the International Reference Ionosphere (IRI)

A new neural network (NN) based global empirical model for the foF2 parameter, which represents the peak electron density has been developed using extended temporal and spatial geophysical relevant inputs. The first results from this new model were presented at the International Reference Ionosphere (IRI) 2006 workshop in Buenos Aires, Argentina, and showed that this new model would be a suitable replacement for the URSI and CCIR maps currently used within the IRI model for the purpose of F2 peak electron density predictions. Measured ground based ionosonde data, from 85 global stations, spanning the period 1995–2005 and, for a few stations from 1976 to 1986, obtained from various resources of the World Data Centre (WDC) archives (Space Physics Interactive Data Resource SPIDR, the Digital Ionogram Database, DIDBase, and IPS Radio and Space Services) have been used for training a NN.     

一种用于图像翘曲变换的高速缓冲存储器设计

车载平视显示（HUD）系统通过图像翘曲变换将原始平面图像信息显示在挡风玻璃曲面上，原始图像数据的非线性访问会造成存储器访问效率下降。为此，设计了一种高速缓冲存储器（Cache），以最大程度保证像素数据访问的连续性，减少存储器访问次数并提高带宽资源利用率。为优化Cache性能，提出存储空间分离管理技术和地址分级比较技术，提高图像像素在Cache中的存储密度，并节省逻辑资源。此外，提出一种Cache容量动态调整的方法，在保证命中率前提下减少Cache存储资源的使用、降低功耗。实验结果显示，存储空间分离管理技术使存储资源节省25%，地址分级比较技术使逻辑资源节省近10%，Cache容量可以减少75%，且动态功耗减少67.578%，静态功耗减少14.060%。      

How the astronomical aspects of climate science were settled? On the Milankovitch and Bacsák anniversaries,with lessons for today

It was 100 years ago (on August 7, 1920), that the comprehensive mathematical foundations of climate change research, written by a Serbian researcher, Milutin Milankovitch, were published. A later interpreter and developer of his results, Georg (in Hungarian: György) Bacsák (Pozsony/Pressburg/Bratislava, June 5, 1870 - Fonyód, March 4, 1970) was born 150 years ago and died at the age of one hundred, half a century ago. In this commemorative paper we look back to special circumstances in revealing the secrets of ice ages that had puzzled scientists for at least several centuries. Recently, after 100 years, the Milankovitch theory, including related short-term forcings (ranging from interannual, multidecadal to millennial timescales) has not only been confirmed, but its climate forcing mechanism has also been identified and proposed. Owing to the uniqueness of the problem, the science of the orbital forcing of climate change can be proclaimed to be essentially settled.     

基于FPGA的CCSDS星载数据无损压缩系统设计

星载数据的无损压缩对星载数据的存储和传输具有重要意义.CCSDS推荐的RICE算法对于实现数据的无损压缩具有很好的效果.本文针对RICE算法中k值选择算法计算量大的缺点,利用预处理样本最大值优化k值的方法,使优化后的算法计算复杂度更低,资源占用率更小,运行时间更短,但压缩比相近.利用FPGA进行硬件实现并通过仿真和试验测试,使星载数据的压缩比达到1.5以上,可以满足星载系统对数据压缩的要求,为星上其他载荷提供更多资源.      

面向深空探测应用的集成一体化载荷数管技术

深空探测对探测器有效载荷电子学及数管的轻小型化和自主能力提出了更高要求.将各载荷电子学与传统的载荷数管集成一体化设计,构建新型高度集成的载荷数管体系结构,可以实现资源集约利用,提高信息融合能力,利于实施自主管理.本文介绍了嫦娥系列探测器载荷电子学及数管设计的现状;提出两种新型一体化载荷数管体系结构,其中第一种低成本集成化方案已应用在中国首次火星探测任务中;通过对未来深空探测载荷数管的技术需求进行分析,对载荷数管发展趋势进行了展望.      

基于启发式算法的可重构性指标分配

串联有约束条件下的可重构性指标分配问题,针对考虑部件故障的系统给出了可重构度的概念和计算方法,并论证了其合理性.结合最优冗余分配理论和可重构度定义给出了可重构度最大化的冗余分配模型,在此基础上提出了基于启发式算法的可重构性指标分配方法,该方法可解决约束条件内资源优化配置问题,并得到系统最大可重构度的解.直接寻查法作为以往具有代表性的最优冗余分配方法,用作系统可重构性指标分配仿真,与所提方法作比较,结果显示基于启发式算法的可重构性指标分配方法较前者有更高的有效性.     

利用GPS实现高轨卫星定位的抗远近效应算法

针对GPS应用于高轨卫星定位面临的远近效应问题, 提出利用正交相关的联合极大似然估计算法来对GPS信号进行二维搜索, 可以得到正确的码延时及多普勒估计. 极大似然估计算法首先利用滑行相关法对仿真信号中的强信号进行搜索, 得到强信号模型, 然后利用正交相关去掉强信号, 最终实现对弱信号的正确捕获. 本文对高轨卫星接收到的GPS信号进行了功率分析, 并建立了信号模型, 进行了算法仿真. 结果表明, 这种估计算法能够提高二维搜索性能, 有效解决远近效应问题.      

GTO发射轨道的两级分解全局优化设计策略

文章提出了包含两级规划、轨道分解优化以及混合遗传算法的GTO发射轨道优化设计策略。针对最优控制变量和总体变量耦合所带来的收敛性差问题 ,建立了两级规划模型 ,其中上面级问题处理总体变量 ,下面级问题处理单独的轨迹控制变量。整个发射轨道优化设计问题被划分成两个轨道段优化设计子问题 ,采用串行混合遗传算法完成子问题的求解。选择一个二级GTO运载火箭 ,进行最大运载能力优化设计 ,对俯仰角选择、发射轨道参数选择等问题进行了分析 ,得出了一些有益的结论。算例分析结果表明所提出的GTO发射轨道优化设计策略的优良性能 ,在运载火箭总体设计中有良好的应用价值。