成分数据的空间自回归模型

针对已有成分数据线性回归模型对研究对象相互独立的严格要求,提出了含有成分数据和普通数据的空间自回归模型,在此基础上提出了成分数据空间自回归模型的估计方法。新模型结合了空间自回归模型处理因变量之间相互依赖的优势,可同时处理成分数据和普通数据。通过利用等距对数比（ilr）变换将成分数据解约束,得到了新模型的参数估计量。蒙特卡罗模拟实验验证了所提估计方法的有效性。      

基于广义S变换的空间锥体进动微多普勒分析

锥体进动特性是用于空间目标识别的重要依据之一.为了研究这一问题,提出一种基于广义S变换的空间锥体进动微多普勒特性分析方法.根据锥体进动的物理运动过程建立了相应的数学模型,推导出锥体进动微多普勒频率的理论表达式,并通过仿真结果验证其正确性.该模型采用共原点的目标多坐标体系,使其仅存在旋转关系,从而简化了模型的结构与计算复杂性.在此基础上,利用广义S变换实现了对模拟雷达进动回波的微多普勒特性分析.在不同信噪比条件下的仿真结果表明:该方法时频分辨性较好,而且具有较高的鲁棒性.     

实心圆柱式永磁同步电机转子偏心气隙磁场的空间和频率特性

针对两极平行充磁实心圆柱式永磁同步电机(SCPMSM),分析转子偏心对气隙磁场空间和频率特性的影响。通过引入转子静态偏心和动态偏心磁导修正系数,建立了转子偏心气隙磁场的数学模型,分析了空载和负载情形下转子静态偏心以及动态偏心气隙磁场的空间和频率特性。以1台2极12槽SCPMSM为例,对转子偏心气隙磁场特性进行了有限元分析,验证了理论分析的正确性。     

激光测距传感器光束矢向和零点位置标定方法

激光测距传感器常用于飞机壁板法向检测。为了解决激光测距传感器加工和安装误差导致的法向检测精度下降问题,提出和实施了一种利用几何数学模型和最小二乘法进行激光测距传感器光束矢向和零点位置标定的方法。首先,利用角度标定理论获取激光束与主轴进给方向的夹角。然后,借助激光跟踪仪建立坐标系,根据激光测距传感器射在与电主轴进给方向成不同夹角的平面上的测量值,利用几何数学模型计算出各激光点之间的相对坐标,运用最小二乘法拟合出激光束的空间方程,进而得到光束矢向和零点位置。最后,在航空制孔机器人平台上进行标定实验,并且根据标定结果进行了实验验证。实验结果证明:该方法能够较为准确地标定出激光测距传感器的光束矢向和零点位置,可使法向检测精度在0.18°内。      

协同控制下的空间信息网络简单虚拟局域网构想

针对空间信息网的组网实现问题,考虑卫星通信网络的长时延、动态性、资源受限等网络特性,提出了一种协同控制下的虚拟局域网组网构想：首先,通过将空间信息网络划分成多个虚拟局域网的方法分割空间广域网,减轻星载计算机的信息处理负担和带宽资源的无谓损耗。其次,基于一致性算法,在协同控制律中加入路由算法实现虚拟局域网内节点卫星信息的两两联通,提高空间信息网络的可靠性和协同处理性能,将这种时变时滞协同控制律应用在空间信息网结构中能够实现空间强连通组网,应用于单个卫星上则可以实现关键节点卫星的冗余备份和负载均衡。最后,模拟仿真空间信息网框架结构和冗余节点虚拟局域网,在50s内迅速实现预定轨迹收敛,且收敛后具有较为稳定的星间时延,从而验证了方案的可行性。     

再入飞行器脉动压力环境特性分析

文章通过数值求解球头单锥飞行器绕流流场结构,利用均方根脉动压力系数、功率谱密度和窄带空间相关系数3个统计参数分析飞行器湍流附面层脉动压力环境特性,为飞行器结构改进设计提供依据,并为飞行器环境条件加载位置、加载密度等参数的确定提供参考。研究结果表明,脉动压力强度沿流向逐渐减小,压力脉动能量主要集中在比湍流附面层脉动特征频率小的频域内;脉动压力空间相关性沿流向逐渐增强,其衰减能力随间隔距离的减小而增加,符合脉动压力的传播和衰减特征。     

Individual Differences in Representational Precision Predict Spatial Working Memory Span

Perhaps the signature feature of working memory is that it is limited. In the same subjects, we used two different retrieval tasks to independently measure two different limits of spatial memory. Precision was measured by asking participants to localize a missing target item among a field of other targets and distracters. Capacity was measured with a similar task where participants identified, rather than localized, a set of remembered targets from within a larger set of identical items. Across participants, the precision of localization was positively correlated with the number of successfully retrieved items. These data suggest that an individual's representational capacity may ultimately be constrained by their ability to form precise representations of space.     

Learning Spatial Localization: From Rat Studies to Computational Models of the Hippocampus

In his landmark article, Richard Morris (1981) introduced a set of rat experiments intended “to demonstrate that rats can rapidly learn to locate an object that they can never see, hear, or smell provided it remains in a fixed spatial location relative to distal room cues” (p. 239). These experimental studies have greatly impacted our understanding of rat spatial cognition. In this article, we address a spatial cognition model primarily based on hippocampus place cell computation where we extend the prior Barrera–Weitzenfeld model (2008) intended to allow navigation in mazes containing corridors. The current work extends beyond the limitations of corridors to enable navigation in open arenas where a rat may move in any direction at any time. The extended work reproduces Morris's rat experiments through virtual rats that search for a hidden platform using visual cues in a circular open maze analogous to the Morris water maze experiments. We show results with virtual rats comparing them to Morris's original studies with rats.     

Qualitative Spatial Reasoning in Interpreting Text and Narrative

Abstract

Simple natural language texts and narratives often raise problems in commonsense spatial knowledge and reasoning of surprising logical complexity and geometric richness. In this article, I consider a dozen short texts—five taken from literature, the remainder contrived as illustrations—and discuss the spatial reasoning involved in understanding them. I conclude by summarizing their common features, and by tentatively drawing some morals for research in this area.     

基于空间7R机构的联轴器运动学及动力学仿真

应用机械系统动力学仿真分析软件ADAMS,建立了基于空间7R机构的联轴器的仿真模型,并进行了运动学和动力学仿真分析;结合有限元仿真分析软件ANSYS,进一步对该联轴器在转动过程中的应力变化进行了分析。为基于空间7R机构的联轴器的设计提供了理论依据,通过CAE仿真软件对基于空间7R机构的联轴器进行运动和动力性能分析,为该联轴器的实际应用以及进一步的分析打下了良好的基础。