An Investigation into Vertical Bias Effects

ABSTRACT

In three experiments, after exploring a virtual environment (VE), adult participants made spatial judgments about the location of target objects that were higher and lower than their perceived test location within the VE. In Experiment 1, the locations of the target objects were inferred from verbal instructions. The main results were a tendency to judge objects as closer to the horizontal plane than their true locations, and more efficient downward than upward judgments. Both effects generally accord with findings reported by Wilson et al. (2004a Wilson, P. N., Foreman, N., Stanton, D. and Duffy, H. 2004a. Memory for targets in a multilevel simulated environment: Evidence for vertical asymmetry in spatial memory. Memory & Cognition, 32: 283–297. [Crossref] , [Google Scholar], 2004b Wilson, P. N., Foreman, N., Stanton, D. and Duffy, H. 2004b. Memory for targets in a multi-level simulated-environment: A comparison between able-bodied and physically disabled children. British Journal of Psychology, 95: 325–338.  [Google Scholar]). In Experiments 2 and 3, which were closely modeled on the design of the Wilson et al. studies, regression to the horizontal plane was noted but no downward bias was observed. A misperception in the viewing height between the floors and ceilings of the virtual rooms was apparent in both experiments. The results from the present study together with earlier investigations suggest different hierarchical encoding of between-axis and within-axis information.     

一种高超声速滑翔飞行器轨迹智能预测方法

针对高超声速滑翔飞行器(Hypersonic glide vehicle, HGV)机动性强、轨迹预测困难的问题,选取气动加速度作为预测参数,提出了一种基于集合经验模态分解和注意力长短时记忆网络的HGV轨迹智能预测方法。首先,以HGV六自由度运动方程为基础,分析了其机动特性和气动力变化规律,建立了动力学跟踪模型,对气动加速度进行实时估计;其次,利用集合经验模态分解对估计的气动加速度进行分解和重构,减弱噪声影响,避免对预测模型的干扰;最后,利用去噪后的气动加速度数据对注意力长短时记忆网络进行训练,进而预测未来气动加速度数据并重构HGV未来轨迹,实现轨迹的在线预测。实验仿真表明,该方法能有效预测HGV机动轨迹,预测精度高、稳定性好。     

Sliding mode control based guidance law with impact angle constraint

The terminal guidance problem for an unpowered lifting reentry vehicle against a sta- tionary target is considered. In addition to attacking the target with high accuracy, the vehicle is also expected to achieve a desired impact angle. In this paper, a sliding mode control （SMC）-based guidance law is developed to satisfy the terminal angle constraint. Firstly, a specific sliding mode function is designed, and the terminal requirements can be achieved by enforcing both the sliding mode function and its derivative to zero at the end of the flight. Then, a backstepping approach is used to ensure the finite-time reaching phase of the sliding mode and the analytic expression of the control effort can be obtained. The trajectories generated by this method only depend on the initial and terminal conditions of the terminal phase and the instantaneous states of the vehicle. In order to test the performance of the proposed guidance law in practical application, numerical simulations are carried out by taking all the aerodynamic parameters into consideration. The effec- tiveness of the proposed guidance law is verified by the simulation results in various scenarios.     

三维内转式进气道对双旁进气飞行器力矩特性的影响分析

为了研究三维内转式进气道对飞行器力矩特性的影响规律,对一系列设计状态为Ma=6.5的内转式进气道展开力矩特性研究。对不同布局形式,进气形式以及基准流场中心体的内转式进气道对飞行器力矩特性的影响展开分析研究。研究结果表明,对于内转式进气道而言,有连接板的水滴型进气道双侧布局力矩特性较优,且容易满足飞行器总体需求;布局形式对进气道的力矩特性影响最显著,进气形式对侧滑力矩的影响比基准流场中心体影响更明显,而抬头力矩和滚转力矩受基准流场中心体影响更加突出;中心体在0~0.1Rs(Rs为基准流场入口半径)变化时,抬头力矩变化不大,而在0.1~0.2Rs抬头力矩变化明显。     

倒立摆系统的建模与积分滑模控制

在研究了倒立摆系统动力学模型的基础上,提出了一种积分滑模变结构的控制方法。通过设计积分性质的非线性滑模面,可以减少系统静差,提高控制精度,系统鲁棒性能获得了很好的保存。仿真证明,该方法能够在较短时间内实现系统的稳定,提高系统的控制精度,使倒立摆系统具有更高的稳定性和鲁棒性。     

脉冲雷达凝视模式下低轨碎片相对运动特征分析

脉冲雷达凝视模式是一种探测低轨小碎片的重要方式,其中低轨碎片与雷达的径向运动关系是碎片统计分析的基础.为推算碎片相对雷达的运动特征,基于坐标系的相互转换,先利用雷达测站信息,得到可见碎片在地惯坐标系下的轨道信息;再逆向将目标不同时刻的位置转换至测站坐标系下,得到目标的径向运动特征.在不同要素（雷达波束指向、雷达仰角、测站纬度、目标距离）下,仿真及对比分析了各个参数对速度模糊度、雷达可见性等的影响,得出在凝视模式下目标相对雷达近似做径向匀加速运动,这为后续试验工作提供有力的依据.     

基于滑模自适应控制的不确定混沌系统修正函数投影同步

研究了一类不确定混沌系统的修正函数投影同步。首先,设计了一类滑模曲面;基于该曲面设计了同步控制器,并采用自适应技术设计了自适应律对不确定参数进行逼近。在一定条件下,该同步控制方案可以实现2个不确定异结构混沌系统的修正函数投影同步。然后,为保证合适的控制量,对控制增益进行了优化。从同步效果来看,所设计的控制器对混沌系统的不确定项的影响具有较强的鲁棒性。最后,数值仿真验证了该控制器的有效性和可行性。     

Categorical Bias in Line Angle Judgments: Sex Differences and the Use of Multiple Categories

According to the Category Adjustment (CA) model, spatial estimates (e.g., of location) involve Bayesian combination across multiple, hierarchical pieces information, each weighted by its relative certainty. Recent work, though, has shown that men and women differ in terms of their certainty regarding fine-grained and categorical information in location memory. Here we demonstrate that this reflects a more general sex difference in visuospatial processing by examining bias patterns in a line angle judgment task (JLAP-15). In addition, the data suggest that multiple, hierarchical levels of categorical information influenced spatial judgments. These results imply that the hierarchical combination outlined by the CA model extends beyond two levels, and that men and women apply differential weighting to these representations.     

滑动运行继电式激光制导系统

 继电控制式激光制导系统的简单性使它具有高可靠性、低成本等优点。而系统自振使得弹着点散布大,降低了制导精度。将滑动运动模态引人系统,使其变成滑动运行的继电控制方式。结果,弹着点散布压缩,制导精度提高,而且保持了原系统的优点。介绍了该系统的组成,分析了提高制导精度的原理,并提供一些仿真结果。     

造型细节和离地间隙对轿车气动性能影响研究_修改稿

汽车造型的不同处理方法、发动机安放位置、离地间隙、发动机舱冷却风的排出模式对轿车气动性能产生影响。应用FLUENT软件，分别对汽车造型的不同处理方法、发动机安放位置、离地间隙、发动机舱冷却风的排出模式进行气动性能仿真。结果表明：汽车造型的处理方法中以加车轮和加发动机舱对气动性能影响最大，发动机存在最佳的安放位置，不同的离地间隙对仿真结果影响很大，选择发动机舱冷却风的排出模式要综合考虑阻力系数和升力系数。