Assessment of between-floor structural and topological properties on cognitive map development in multilevel built environments

The present study investigated cognitive map development in multilevel built environments. Three experiments were conducted in complex virtual buildings to examine the effects of five between-floor structural factors that may impede the accuracy of humans’ ability to build multilevel cognitive maps. Results from Experiments 1 and 2 (of three experiments) revealed that difficulties in developing multilevel cognitive maps are not solely caused by the z-axis offset, as is suggested in the literature, but are due to the factorial combination of a between-floor overlap and a z-axis offset. Results from Experiment 2 showed that this process becomes substantially more difficult when the reference directions between different floors have an angular offset from each other. Finally, results from Experiment 3 demonstrated that confusing between-floor heading shifts in aligned buildings did not make it reliably harder to build multilevel cognitive maps. The implications of these findings are discussed in terms of theories of mental representations in multilayered three-dimensional spaces, as well as for architectural design.     

RN-FD型固体氡气源的稳定性及应用分析

对测氡仪器进行精确校准是氡测量工作中的重要环节,固体氡气源的稳定性、可靠性在校准中则显得至关重要。本文通过分析RN-FD型固体氡气源对闪烁室K值的稳定性实验结果,认为:RN-FD型固体氡气源标称的浓度值与实际浓度值不一致,标称浓度值只是理论浓度值而不是实际浓度值,需重新刻度才能使用;RN-FD型固体氡气源抽气循环时间不同则浓度不同,但抽气循环时间固定,观测结果比较稳定;对于没有α检查源的台站,RN-FD型固体氡气源可用于氡观测仪器坪区检查。     

高温环境下大尺度薄壁结构的电性能优化设计

考虑温度引起的热变形和材料电磁参数变化对天线罩电性能的影响,基于口径积分-表面积分法(AI-SI)和有限元法(FEM),提出了高温环境下天线罩电性能分析方法;进而基于粒子群算法(PSO),建立了计及热效应的天线罩结构电性能优化流程。分别选取常温环境、均匀高温环境和非均匀高温环境三种典型工况,对比研究了温度对天线罩电性能的影响规律,并对天线罩电性能进行了优化,研究结果表明:高温会引起天线罩透波系数的下降和瞄准误差的上升,在天线罩优化设计中应重视温度对电性能的影响;计及热效应的天线罩结构电性能优化方法能显著提升天线罩的透波系数、降低瞄准误差,具有良好的优化效果。     

一种GPS抗干扰及干扰DOA估计工程集成方法

卫星导航干扰对消技术和干扰测向技术是卫星导航干扰对抗的两个典型方向,并逐渐成为当前卫星导航抗干扰装备的标配功能。如何实现干扰对消和干扰测向的高效集成成为制约工程实现的主要瓶颈之一。提出一种GPS抗干扰及DOA估计的工程集成方法,通过优化噪声子空间估计工程实现,实现了高性能抗干扰和高精度干扰测向的高效集成,与抗干扰模块和干扰测向模块相比,集成模块极大降低了工程实现资源。测试结果表明该方法可以有效对抗干信比60dB的干扰,并提供2度的测向精度。     

超宽带变频系统中的本振产生技术研究

本振源是超宽带变频系统中的核心部件，本文以超宽带上变频系统为例，介绍变频系统中本振信号的产生技术。本文所设计的超宽带变频系统，经过三次上变频，可将(0.8~2.8)GHz 的低频信号变换至（0.5~40）GHz。变频过程中需要一系列点频本振和一组宽带本振，基于PLL+DFS 的方法产生点频本振，基于DDS+DFS 的方式产生宽带本振。     

航天器近距离交会的固定时间终端滑模控制

针对航天器近距离交会段的位置姿态耦合控制问题，假设航天器受外界干扰且目标航天器存在空间自由翻滚情形时，基于固定时间概念设计了一种六自由度位姿终端滑模自适应控制器，通过引入显含正弦函数的切换项来避免奇异问题。此外所设计的控制器含双幂次项，不仅能全局提高姿态和位置的跟踪速度及精度，还能估计系统稳定所需的时间上界，且该上界与状态初始值无关。基于Lyapunov方法分析了闭环系统的固定时间稳定性。仿真结果表明，该控制器能快速实现对航天器近距离交会时相对位置和姿态的控制，具有较高的精度和良好的干扰抑制能力。     

基于EVENT模型的单向循环航路侧向碰撞风险分析

我国空域骨干航路拥挤不堪,一些支线航路的利用率却很低,单向循环航路的出现很好地解决了这一问题,对其进行安全评估是划设航路最重要的工作之一。在总结EVENT理论和相关文献的基础上,对单向循环航路和混合航路侧向碰撞风险进行比较分析,推算出目标安全等级下单向循环航路容量,并对单向循环航路侧向碰撞风险进行预测。结果表明,单向循环航路侧向碰撞风险远低于混合航路侧向碰撞风险,且未来10年均保持在比较稳定的安全水平。     

The Kumtag meteorite strewn field

The Kumtag meteorite strewn field was found in the Kumtag desert, 132 km south of Hami city in the Xinjiang province, China. It is an ellipse of 2.5 × 7.9 km, with a long axis extending along the northeast-southwest direction. The largest individual meteorite of the strewn field weighs about 10 kg; the smallest individual has a mass of only 27 g. In total, more than 100 individuals with a total mass of more than 180 kg were collected. The location and the distribution of the fragments suggest that the Kumtag meteoroid entered the atmosphere in the direction Northeast-Southwest. All meteorites collected in this strewn field are samples from the same unique meteorite shower. The Kumtag meteorite is an H5 ordinary chondrite with a shock stage S2, and a weathering grade W2. The cosmic ray exposure age of Kumtag is 6.7 ± 0.8 Ma, which is rather typical for H chondrites and which indicates that Kumtag was derived from the massive impact event on its parent body ~7 Ma ago. A significant amount of He has been lost during certain unknown processe(s) before the Kumtag meteorite was ejected from its parent body.     

基于子阵级非周期的有限扫描阵列研究

对基于子阵级非周期的有限扫描阵列进行研究,采用数值仿真和遗传算法对基于不同子阵规模的非周期阵列进行优化设计,分析4?4和2?2两种子阵规模对接收多波束应用中伴随波束方向图的影响,研究表明子阵规模过大会引起伴随波束方向图的旁瓣抬升,通过减小子阵规模可以避免该问题,论证了设计的基于2?2子阵的非周期八角阵可应用于有限视场扫描相控阵中。