Application of ERS-1 scatterometer data to studying land surfaces ──Distributive characteristic of backscattering coefficient over China land surfaces

ERS 1 WSC data were obtained by international cooperation. The distributive characteristics of radar backscattering coefficient image of China land surface are analyzed and the research results are presented. The capability of ERS 1 WSC data for monitoring land surfaces is investigated. The results show that the radar backscattering coefficient images can reveal the natural landform features of China land. Using the WSC data can discriminate six types of major land coverage, including evergreen vegetation and snow covered region, vegetation and crops, mountains, grassland, desert and grassland, desert. On the whole, the radar backscattering coefficient image of China land is the synthesis of the vegetation map and terrain map. Statistical study of the typical terrain shows that the radar backscatter coefficients of China land range from -29 dB to -5 dB. The lowest value corresponds to the deserts of Badain Jaran, Takla Makan, and Tengger. The highest value corresponds to snow covered regions of Himalaya Mountains and Tianshan Mountains.     

基于感觉运动BCI系统的EEG手部运动分类

对于残疾人或者运动不便的健全人,感觉运动相关的BCI（Brain Computer Interface）系统是十分必要的.BCI系统的关键部分是对EEG（Eletroencepalograph）信号的采集、提取和分类.本文研究的是手部三种动作在运动执行的情况下,人脑产生的EEG信号的不同.利用EEG信号在运动时发生于大脑感觉运动皮层区域的ERS（Event-Related Synchronization）和ERD（Event-Related Desynchronization）现象,运用EMD（Empirical Mode Decomposition）等算法进行信号的特征提取,然后进行分类,得出了平均准确率为78.75％的良好结果.此次研究提供了一种基于EMD新的有效的运动相关BCI系统研发中的EEG信号的特征提取算法.     

一种变步长前瞻性电子侦察卫星引导调度方法

针对存在区域先验信息的电子侦察卫星引导调度问题,提出了一种变步长前瞻性引导调度机制.以卫星实时侦察信息引导后续有限步长内的卫星侦察策略,随着侦察信息的不断下传形成滚动推进的引导调度窗口;提出了一种基于贝叶斯规则的更新方法对区域状态进行预测,建立了引导调度窗口内有限前瞻步长的通用多目标规划模型,并针对模型特点设计了一种改进型多目标蚁群算法进行求解.仿真对比实验表明,该方法能够有效解决面向区域搜索的电子侦察卫星引导调度问题.     

EEG-based asynchronous BCI control of a car in 3D virtual reality environments

Brain computer interface (BCI) aims at creating new communication channels without depending on brain’s normal output channels of peripheral nerves and muscles. However, natural and sophisticated interactions manner between brain and computer still remain challenging. In this paper, we investigate how the duration of event-related desynchronization/synchronization (ERD/ERS) caused by motor imagery (MI) can be modulated and used as an additional control parameter beyond simple binary decisions. Furthermore, using the non-time-locked properties of sustained (de)synchronization, we have developed an asynchronous BCI system for driving a car in 3D virtual reality environment (VRE) based on cumulative incremental control strategy. The extensive real time experiments confirmed that our new approach is able to drive smoothly a virtual car within challenging VRE only by the MI tasks without involving any muscular activities. Supported by the National High-Tech Research Program of China (Grant No. 2006AA01Z125) and the National Basic Research Program of China (Grant No. 2005CB724301)     

基于ICA与PSD的ERD／ERS信号检测

介绍一种基于独立分量分析（ICA）空间滤波结合功率谱密度（PSD）曲线分析法用于提取大脑在想象动作时产生事件相关去同步／同步（ERD／ERS）信号的方法．其检测流程为：先对想象动作诱发的脑电（EEG）信号进行ICA分解得到独立分量与相应的解混矩阵,再按特征频段取其主要分量得到滤波后数据,然后采用短时傅里叶变换计算相关导联EEG信号在特征时段与频段的PSD曲线,引入ERD／ERS系数作为量化指标以进行想象动作的识别．计算结果表明,上述方法能够显著增强运动想象脑电信号的ERD／ERS特征信息,且通过实际分类验证,采用该方法可以获得更高的识别正确率,较传统信息检测方法平均提高8％以上．     

导电性聚席夫碱的研究——Ⅲ.碘掺杂含硫聚席夫碱的ESR波谱

共轭型含硫聚席夫碱以碘掺杂后,其宏观导电性会大幅度增加(从10~(-11)S/cm增至10~(-3)S/cm)。为了解释这一掺杂过程的微观变化,对碘掺杂含硫聚席夫碱进行了ESR波谱分析。结果表明,聚合物在掺杂过程中,会形成自旋性阳离子自由基=(?)—(极子)。随着掺杂度提高,聚合物导电性一直增加,而样品中自旋浓度则首先增加,然后逐渐降低,表明由掺杂而形成的极子会部分地转变为无自旋的双极子。还探讨了聚合物掺杂过程中ESR峰形及线宽的变化原因。