通量限制器与LED性质、空间离散精度

本文从标量形式的ＵＳＬＩＰ格式出发,从理论上分析了通量限制器与ＬＥＤ性质和空间离散精度的关系。利用Ｒｏｅ平均矩阵的Ｕ特性和广义数值Ｒｉｅｍａｎｎ不变量的概念,将此类格式应用于二维翼型跨声流场的数值模拟,针对提供的来流条件,考查了不同的通量限制器对流场计算精度的影响。     

一类含小参数微分方程鸭解的存在性

本文应用微分方程定性理论、 渐进分析方法、 隐函数定理以及不动点理论的方法研究一类单参数二维奇异摄动系统.给出了当系统的奇点在破坏点的小邻域时鸭解和鸭极限环存在的充分条件.证明了存在参数值a=a\-c(ε),使得对a\-c(ε)小邻域中的所有参数a, 系统存在鸭极限环.并给出了鸭解和鸭极限环的渐近估计式以及鸭极限环随参数变化的规律.本文推广了文献[1]和文献[2]的结果.     

A New Optimal Hatch Filter to Minimize the Effects of Ionosphere Gradients for GBAS

At present, the main problem faced by ground-based augment system （GBAS） is that though carder smoothing filter and local differential global positioning system （LDGPS） improve the accuracy of the pseudorange by reducing the noise in it and eliminating almost all the common errors between the user and the reference station, they also cause extra errors on account of the effects of the ionosphere temporal and spatial gradients. Based on the analysis of these errors as well as the smoothing noise, this article suggests a new algorithm to design the optimal Hatch filter, whose smoothing window width varies real-time with the satellite elevation, ionosphere variation, and distance from the user to the reference station. By conducting the positioning process in the GBAS emulation platform for several hours and after its comparison with the performances of traditional Hatch filters, it is found that the errors in the differential correction become smaller and the positioning accuracy gets heightened with this new method.     

基于SAR图像匹配结果可信度评价的INS/SAR自适应Kalman滤波算法

在惯性导航系统（INS）/合成孔径雷达（SAR）组合导航系统中,SAR图像易受斑点噪声的影响,图像匹配的精度对整个导航系统精度的影响十分明显,能够准确地分析SAR图像匹配过程中的误差特性,利用有效的图像匹配信息辅助INS进行组合定位尤为重要。针对上述问题,在加权Hausdorff距离匹配算法的基础上,对影响SAR图像匹配精度的因素进行了分析,提出了一种基于模糊推理的匹配结果可信度评价准则,经过可信度筛选,将有效的匹配信息与INS进行组合;对合理范围内的匹配误差变化引起量测噪声统计特性发生变化,进而导致Kalman滤波精度下降的问题,研究采用改进的Sage-Husa自适应滤波算法对量测噪声方差阵进行动态调整,使其更加接近系统的当前状态。搭建仿真验证平台对所提算法进行了验证,结果表明,该算法能够在合理的匹配误差范围内,有效地筛选出可信的图像匹配结果,相比常规Kalman滤波算法,显著地提升了INS/SAR组合导航系统水平方向的定位精度。     

一种十字阵列模型下的新型测向算法

为提高精确制导的实时性,实现空间谱测向,提出了一种新型的正交传播算子算法(propagator method,PM)。该算法基于十字型阵列模型,引入了噪声子空间的投影算子构造伪谱,并采用一维谱峰搜索实现二维测向。与利用二维谱峰搜索测向的二维PM算法相比,该算法大大减少了计算量,降低了计算复杂度,可实现多目标信号测向,解决了二维角度的配对问题,也可有效估计出相同方位角(或仰角)的目标。该算法可广泛应用在雷达测向、导引头测向及跟踪等。     

面向机电产品布线规划的空间预处理技术

针对面向布线优化求解的空间模型的性能评价研究不足,目前的空间模型仍然广泛存在影响布线算法求解效率和质量的问题,首先建立了布线空间模型性能评价模型;然后分析了布线规划对空间模型的需求,提出了基于八叉树的空间信息模型及其空间预处理技术;最后通过实例验证了基于八叉树的空间预处理技术的有效性,以及布线空间模型评价模型的可行性。     

Interactivity in map learning: The effect of cognitive load

The hypothesis that active learning is beneficial relative to passive observation was assessed in the context of spatial knowledge derived from maps. Active and passive participants studied a map either while performing a simultaneous spatial tapping task (high cognitive load) or in the absence of this task (low cognitive load). Active participants controlled how the map was learned, with passive participants observing map learning without exercising control. Spatial recall was assessed in two tests, directional judgements and map drawing. Map drawing and directional judgments showed a similar pattern of results, with performance detrimentally affected by a high load for active participants, but not for passive participants. The results indicate that activity and cognitive load interact, suggesting that active learning can be detrimental to spatial learning in cognitively demanding tasks.     

Wayfinding Through Orientation

Dominant approaches in computer-assisted wayfinding support adhere to the deeply problematic principles of turn-by-turn navigation. In this article, we suggest a new approach called “Wayfinding Through Orientation,” which supports the acquisition of spatial knowledge and cognitive mapping for advancing the user’s spatial orientation. Being oriented on one’s way is a prerequisite to enabling people to verify instructions and to incorporate new spatial information into their existing knowledge structure. In three studies described in this article we first present empirical evidence that people can be supported in survey knowledge acquisition through suitable wayfinding instructions. Consequently, we explore orientation information in human wayfinding instructions. Finally, we outline how orientation information can be communicated within a prototypically implemented navigation assistance system.     

卫星天线振动信息融合试验研究

讨论了D -S证据推理理论 ,给出了传感器特征信息融合算法。结合卫星天线振动频率分配控制问题 ,进行相应的实验研究 ,对传感器的特征信息进行融合 ,给出了振动响应频率特征信息提取方法 ,剔除边界条件对测试结果置信度的影响