Relation algebras over containers and surfaces: An ontological study of a room space

Recent research in geographic information systems hasbeen concerned with the construction of algebras tomake inferences about spatial relations by embeddingspatial relations within a space in which decisionsabout compositions are derived geometrically. Wepursue an alternative approach by studying spatialrelations and their inferences in a concrete spatialscenario, a room space that contains such manipulableobjects as a box, a ball, a table, a sheet of paper,and a pen. We derive from the observed spatialproperties an algebra related to the fundamentalspatial concepts of containers and surfaces and showthat this container-surface algebra holds allproperties of Tarski's relation algebra, except forthe associativity. The crispness of the compositionscan be refined by considering the relative size of theobjects) and their roles (i.e., whether it isexplicitly known that the objects are containers orsurfaces).     

星载ADS-B相关研究进展及展望

星载ADS-B技术作为未来空中交通管制的重要技术,可以克服地面设备难以在荒漠、远洋、极地等地部署的难题.星载ADS-B具有侦收范围广、可全球覆盖的特点,由此各国纷纷展开相关研究.针对星载ADS-B技术特点,进行了星载ADS-B相关研究进展的调查.首先综述了星载ADS-B原理及相关卫星研究情况;其次围绕天线技术、射频电路...     

空间机器人操作：一种多任务学习视角

利用空间机器人辅助、代替航天员完成在轨服务操作是近年的技术发展趋势。基于学习的空间机器人操作以深度神经网络为控制器载体,对非结构化太空环境适应能力强,在高轨、地外、深空等场景具有良好应用前景。目前,无论是空间机器人操作,还是地面机器人操作,多数研究只关注单一任务学习问题。立足一种多任务学习新视角,针对空间机器人操作面临的多任务适应性要求高、精细化要求高、不确定性强问题,首先分析了在轨服务的多样化任务需求。其次,全面综述了机器人操作多任务学习算法与应用相关工作,分析了开展空间机器人操作多任务学习的难点挑战,给出了关键技术发展建议。相关关键技术的突破将有助于提升空间机器人系统的自主性、鲁棒性,进而助力中国在轨服务技术向无人全自主方向推进。     

基于多项式近似的空间碎片群体轨道预报算法

快速准确地分析空间碎片群轨道演化行为对于其他在轨航天器碰撞规避至关重要。在各摄动力的作用下,空间碎片群演化运动呈现出复杂的非线性特征。空间碎片群体个体数量巨大,如果通过对空间碎片群中每个空间碎片进行轨道积分来分析群体预报的方法会导致计算量过大。针对该问题,提出一种基于多项式近似的轨道快速预报分析方法。该方法将空间碎片群分为少量的标称碎片和其他大量关联碎片。针对标称碎片的轨道预报采用数值积分求解保证预报精度;而针对其他大量的关联碎片轨道预报问题,采用多项式泰勒展开半解析方法求解,从而在保证预报精度的前提下有效减少空间碎片群轨道预报的计算量。为了验证方法的有效性,对不同空间碎片群进行了轨道预报仿真。仿真结果表明,当轨道预报精度设定在1m范围内时,多项式近似算法的计算量较蒙特卡洛方法计算效率提高了2.2~17.2倍,验证了所提出方法的有效性。     

适用于深空探测器的时间线转移路标启发式规划方法

针对深空探测器各子系统状态并行及约束耦合的特点,设计了最大转移代价计算方法,并在此基础上提出了时间线路标提取方法。然后,针对路标集合重复计算耗时长的问题,提出了路标增量式搜索算法实现路标集合动态快速更新,并进一步结合最大目标节点筛选策略提出了时间线转移路标启发式规划方法。仿真结果表明,时间线转移路标启发式规划方法能够有效减少冗余规划步数,提高规划求解效率。     

空间拦截修正比例导引律研究

基于追踪导引律和比例导引律,提出了一种新的空间拦截末制导律。通过调整两种导引法的系数决定其在导引法中的权重。考虑空间末段拦截的具体情况,在相对运动方程进行线性化处理的基础上可以得出运动方程的解析解。将非线性方程得出的数值解和这种导引律的解析解相比,仿真表明这种方法的解析解与数值解一致,且避免了最优制导复杂的解析结果。     

Examining the effects of anti-space weaponization arguments in the media: Some experimental findings from Canada

This study examines how political activists are framing the space weaponization debate in Canada and whether their arguments can influence public attitudes and perceptions about the issue. Eighty university students from two undergraduate courses were recruited as participants in a quasi-experiment. One class (n = 38) was exposed to the documentary Masters of Space, an episode of the Canadian Broadcasting Corporation's program The Nature of Things, and another class (n = 42) served as the control group. Pre-test and post-test questionnaires were used to measure the effects of viewing anti-weaponization arguments in the media, while also controlling for the influence of prior beliefs and background characteristics of participants. Results suggest that visually depicting the use of satellite technology in society can convince viewers that satellites are important to their way of life, but not necessarily to the defense of North America. Framing missile defense as a ‘space weapon in disguise’ also seemed to raise opposition to Canada's participation in continental missile defense. The findings, meanwhile, indicate that viewers respond strongly to the issue of space debris and that mobilizing support for joint military space projects may best be achieved by emphasizing the usefulness of these projects for locating and tracking such debris. In the end, media exposure seemed to help legitimize anti-weaponization arguments based more on rational self-interests than on idealistic beliefs. These findings can have implications for the way space policies are communicated to the public.     

基于改进Hough变换的临近空间高超声速目标航迹起始方法

针对传统算法不能对临近空间高超声速目标进行有效航迹起始的问题,提出了一种基于改进Hough变换的快速航迹起始方法.量测数据经过Hough变换后,首先提取出参数空间中超过阀值的峰值点,形成备选积累单元位置矩阵,然后将备选积累单元位置矩阵中各列元素与本列各元素相减,并将超过距离偏差和角度偏差的点剔除,得到差值单元位置矩阵,最后对差值单元位置矩阵对应参数空间的所有点求均值,将均值作为曲线在参数空间的交点起始目标航迹.Mont Carlo仿真表明,新方法能够实现对多批临近空间高超声速目标的航迹起始,有效解决了航迹簇拥问题,具有一定工程实践意义.     

空间机械臂视觉相机内参标定技术研究

针对空间机械臂视觉相机的任务需求与配置,内参标定技术是相机高精度获取合作目标位置、方向等运动信息的首要前提和重要保障。文章设计了一种基于二维平面靶的机械臂相机内参标定方法,用于解算焦距、主点坐标、畸变系数等。首先,利用相机拍摄多幅平面靶图像,求解平面靶与相机图像之间的映射矩阵;其次,构建相机内参约束方程;再次,利用特征值分解,解算焦距、主点坐标等参数值;最后,引入径向、切向畸变构建非线性模型,将解得的内参作为初值,利用Levenberg-Marquardt优化算法即可计算出相机内参最优解。试验结果表明,该方法完全适用于机械臂相机内参标定,标定结果均满足机械臂视觉相机获取合作目标三维位姿的测量精度要求。