Development of Landmark Knowledge at Decision Points

Two experiments investigated how people develop different landmark knowledge at decision points. Participants learned a route in a virtual city once or five times. One distinctive landmark was placed at each intersection of the route. At test, participants were released at each intersection according to the learning order and were required to determine the turning direction. At each intersection, the landmark was removed (no landmark), correctly placed (one landmark), duplicated on the other side (two identical landmarks), or misplaced from another intersection (two different landmarks) to disrupt the landmark sequence. The results suggested that humans develop different landmark knowledge (landmark knowledge for guidance, landmark knowledge for place recognition and knowledge of landmark sequence) with different navigation experience.     

Is Memory for Routes Enhanced by an Environment's Richness in Visual Landmarks?

We tested the hypothesis that a route's memorability is dependent on the frequency with which people are exposed to visual landmarks. Undergraduates learned either a route through an urban area lacking visually salient features, or a route in a neighborhood with many shops and urban objects. They were then asked to recall the learned route in the form of route directions and sketch maps. The results showed higher recall performance for the richer environment. When presented with photographs depicting scenes along the route, participants exposed to the richer environment had higher recognition scores and shorter response times than the others. The data confirm the functional role of landmarks in route memory and wayfinding.     

The Influence of Geometrical and Nongeometrical Features on the Use of the Lexical Concepts NEAR and FAR in English and Finnish

Abstract

This paper investigates the impact of geometrical and nongeometrical features on the use of the lexical concepts NEAR and FAR in English and Finnish. Participants' acceptability ratings for these concepts demonstrate that a bar in between a Figure and a Ground acts as a scale-setting object but not as a distance enhancing barrier, shows that the influence of the geometrical feature Figure–Ground distance exceeds the influence of several nongeometrical features, but most of all reveals that language specific lexical properties associated with NEAR and FAR predict language dependent effects for functional relatedness in interaction with Figure–Ground distance and bar presence.     

一种有效支持空间分析的空间数据组织

Ｒｅａｌｍｓ是一种用于描述空间平面的数学模型。它提出了一种所有空间对象共享一个共同的空间元素集合的思想以及一种空间元素的排序规则。这些特点使得二维空间能够线性化为一维有序的元素集合，将二维空间问题转化为一维线性问题，从而使得基于Ｒｅａｌｍｓ的空间数据组织能有效地支持平面扫描算法。通过对空间对象的简单扫描，能够实现多数空间分析算法。以Ｒｅａｌｍｓ为基础实现空间数据管理系统能取得较高的效率，并且降低了     

特征趋势分区Gauss伪谱法解再入轨迹规划问题

针对强约束下的滑翔再入轨迹规划问题,采用基于特征趋势分区的Gauss伪谱法将连续最优问题转换为多个并行非线性规划问题并对其进行求解。针对传统拟谱方法在处理状态受限时,非平滑最优控制解难以收敛的问题,引入Sobolev空间证明了分区并行的收敛性和一致性。基于Letts准则提出了非连续特征趋势提取方法,通过分析离散点配置导数进行了可变分区的迭代设定,并结合导数变化趋势给出了各分区的动态配点数。利用不同阶次的多项式进行精度逼近,保证了在考虑多项强约束条件下弹道规划的可行解获取。结合状态分区的策略进行离线状态的分解,提高了计算效率。最终针对典型的再入应用进行了轨迹规划应用。仿真结果表明,所提出的方法可有效应对多种约束条件,能够根据飞行器的气动能力规划出可行的轨迹,过程条件满足约束,且可适应气动力20%的拉偏范围。     

“资源三号”卫星正视影像区域网平差

目前卫星影像的区域网平差技术已经有了初步的发展,但大多数研究都基于国际高分辨率卫星影像,针对大区域范围内的中国卫星影像的快速平差还鲜有提及。文章以“资源三号”卫星正视影像为数据源,配合高分辨率的控制点影像和数字高程模型（DEM）数据,基于RPC（rational polynomial coefficients）模型参数精确解算和一种新的控制点选取策略对大区域范围内仅使用少量控制点的区域网平差进行了研究与试验。在试验过程中,文章采用地形坡度统计的方法来快速获取多景影像中控制点的优先选取区域,缩小控制点选取范围。除此之外,文章还通过添加选取相对较为容易的连接点替代部分控制点来保证影像平差精度。结果表明：采用文中方法能大量减少控制点选取难度并有效提高中国遥感影像的几何定位精度,真正实现数字正射影像（DOM）产品的快速生产。     

基于地面任务-空间姿态映射的敏捷卫星任务规划

面向观测时间窗口相互重叠的多点目标观测任务需求,对敏捷卫星单星单轨任务规划问题进行研究。针对传统方法在卫星机动能力受限和成像任务冗余两种情况下求解效率低的缺陷,引入任务-姿态协同规划思想。首先,建立地面任务和空间姿态映射关系,并考虑相邻任务间姿态机动时间的最优性使得卫星在观测相邻任务时无多余等待时间,以此来设计任务-姿态协同规划数学模型。其次,根据任务-姿态协同规划数学模型,设计自适应伪谱遗传算法（APGA）,用以求解满足调整时间最优性的敏捷卫星任务规划问题。最后,通过仿真实验,验证了模型和算法能够有效地解决传统算法求解敏捷卫星任务规划问题时存在的求解效率低的缺陷。     

综合化航空电子分区隔离的建模与设计方法

分区技术是航空电子系统综合化模块化发展中不可缺少的技术.针对航空电子系统安全关键性的要求,基于ARINC653标准,提出了分层分区的体系结构模型,该模型实现了不同安全关键级别应用软件之间的隔离.为了满足航空电子系统强实时可预测性的约束,双层分区模型中系统层采用轮转调度策略,区间层采用单调速率调度策略.然后对分区任务进行可调度分析,在充分保证航空电子系统强实时的前提下,提出了分区关键参数的设计方法,并推导了最坏情况下的系统可调度利用率.计算机仿真结果表明,该方法在保证实时性的同时,能支持更多的系统负载,具有优越性.