Multisensor Estimation Fusion on Statistical Manifold

In the paper, we characterize local estimates from multiple distributed sensors as posterior probability densities, which are assumed to belong to a common parametric family. Adopting the information-geometric viewpoint, we consider such family as a Riemannian manifold endowed with the Fisher metric, and then formulate the fused density as an informative barycenter through minimizing the sum of its geodesic distances to all local posterior densities. Under the assumption of multivariate elliptical distribution (MED), two fusion methods are developed by using the minimal Manhattan distance instead of the geodesic distance on the manifold of MEDs, which both have the same mean estimation fusion, but different covariance estimation fusions. One obtains the fused covariance estimate by a robust fixed point iterative algorithm with theoretical convergence, and the other provides an explicit expression for the fused covariance estimate. At different heavy-tailed levels, the fusion results of two local estimates for a static target display that the two methods achieve a better approximate of the informative barycenter than some existing fusion methods. An application to distributed estimation fusion for dynamic systems with heavy-tailed process and observation noises is provided to demonstrate the performance of the two proposed fusion algorithms.     

SINR- and MI-Based Double-Robust Waveform Design

Owing to cognitive radar breaking the open-loop receiving–transmitting mode of traditional radar, adaptive waveform design for cognitive radar has become a central issue in radar system research. In this paper, the method of radar transmitted waveform design in the presence of clutter is studied. Since exact characterizations of the target and clutter spectra are uncommon in practice, a single-robust transmitted waveform design method is introduced to solve the problem of the imprecise target spectrum or the imprecise clutter spectrum. Furthermore, considering that radar cannot simultaneously obtain precise target and clutter spectra, a novel double-robust transmitted waveform design method is proposed. In this method, the signal-to-interference-plus-noise ratio and mutual information are used as the objective functions, and the optimization models for the double-robust waveform are established under the transmitted energy constraint. The Lagrange multiplier method was used to solve the optimal double-robust transmitted waveform. The simulation results show that the double-robust transmitted waveform can maximize SINR and MI in the worst case; the performance of SINR and MI will degrade if other transmitted waveforms are employed in the radar system.     

Cancer Segmentation by Entropic Analysis of Ordered Gene Expression Profiles

The availability of massive gene expression data has been challenging in terms of how to cure, process, and extract useful information. Here, we describe the use of entropic measures as discriminating criteria in cancer using the whole data set of gene expression levels. These methods were applied in classifying samples between tumor and normal type for 13 types of tumors with a high success ratio. Using gene expression, ordered by pathways, results in complexity–entropy diagrams. The map allows the clustering of the tumor and normal types samples, with a high success rate for nine of the thirteen, studied cancer types. Further analysis using information distance also shows good discriminating behavior, but, more importantly, allows for discriminating between cancer types. Together, our results allow the classification of tissues without the need to identify relevant genes or impose a particular cancer model. The used procedure can be extended to classification problems beyond the reported results.     

基于图像处理的光学谐振腔自准直研究方法

针对我国氧碘化学激光器输出能量不断提高的情况下,主要限制光束质量的因素之一是出光过程中的光腔失调,提出了一种基于图像处理的光学谐振腔自准直研究方法。该研究方法利用氦氖穿腔光通过凹腔镜中心孔,并在凸腔镜后方放置工业相机,在屏幕上方形成一个干涉同心圆环。通过借助OpenCV库中二值化、霍夫圆检测等图像处理的方法,获得干涉同心圆环的圆心坐标,再通过以圆心为中心将图像分成上下左右四个部分,通过判断这四部分亮点像素的数量差值来预估干涉同心圆环的偏移状态,进而获得空腔条件下光学谐振腔发生变化的理论判据。实验结果表明,该方法可以获得相当精准的光学谐振腔失调判据,其失调判据选取左右亮点像素差值30 000,上下亮点像素差值45 000,为今后失调判据与步进电机自动调腔的结合做好充足的准备。

     

强混响背景下悬浮目标的时反成像

提出了一种加权宽带全信号子空间时反成像方法,将扩展性目标建模为有限数量个、相互独立的点散射体构成,实现了时反成像在可疑目标区域的全信号子空间和整个宽带的累加。在实验室波导水池中,底部放置圆柱筒制造混响背景,共进行了两个实验,一是扩展性的悬浮目标位于圆柱筒附近,其回波与圆柱筒反射的混响不在同一个时间窗内,二是弱点目标回波与圆柱筒反射的混响重叠于同一个时间窗内,对所提出的方法进行强混响背景下弱悬浮目标的成像能力验证。结果表明,此方法对强混响背景下的弱悬浮目标的成像质量明显优于传统的时反成像方法。     

论隐私的社会生成机制—以习俗和法律关系为视角

隐私是一种普遍存在的社会制度。它不仅有助于人们维护人格尊严和抵御社会压力,也有助于人群组织或者社会的构成与团结。隐私可以生成为习俗、契约和权利等多种形态。在传统社会,隐私主要以习俗为载体;进入现代社会后,隐私权则成为更主要的隐私制度。出现这一转变的原因在于：信息技术的进步,打破了传统社会阶层之间的信息壁垒;社会物质条件的改善,让人们享有更为独立的私人空间,以及形成了多元化的社会生活场景;人与人之间的亲密性,也因为空间结构以及公私关系的改变,变得越来越淡薄。传统隐私习俗已经不能满足新的社会需求,而隐私权则能更好地适应隐私制度碎片化和个人化的趋势。但是只要人们依然需要社会生活,那么也就需要在人群、组织以及社会范围内分享隐私。因此在现代社会,隐私权不能成为唯一的隐私制度,而隐私习俗依然具有新生的可能性。     

向长波方向发展的光子数分辨探测技术

研究了光子数分辨探测器技术发展的物理基础,技术现状和发展趋势.重点分析了目前能达到单光子分辨的发展中的三种探测技术：越界超导传感技术（superconducting transition-edge sensor）,电荷积分单光子探测技术(charge integration photon detection)和雪崩光电二极管单光子分布探测技术(delayed single photon probability mapping based on avalanche photodiode),讨论了探测器的光子数分辨能力及其噪音来源.     

测定微小晶体结构的电子晶体学图像处理技术

介绍了2005年国家自然科学奖二等奖获奖项目“微小晶体结构测定的电子晶体学研究”.研究目的是建立一种借助高分辨电子显微像测定晶体结构的新方法.为此提出了高分辨电子显微学与衍射晶体学相结合的思想,在实现此思想的过程中,研究了像衬的规律,得出实用的像衬公式和理论,阐明了不同种类原子像衬与晶体厚度的关系,而且用理论指导实验,观察到晶体中锂原子的像衬.以此理论为依据,把衍射晶体学中的多种分析方法特包是直接法引入到高分辨电子显微学中,建立了一套全新的电子晶体学图像处理技术,开发了相应的可视化专用软件包,并应用于测定多个未知晶体结构.文中逐一介绍了研究工作全过程的关键问题和研究结果.     

半导体光放大器的光-光互作用及其应用

半导体光放大器(SOA)中的非线性系数约为普通光纤的109,为光子晶体光纤的107,而且有4种光-光互作用,即交叉增益调制（XGM）、交叉相位调制(XPM)、交叉偏振调制（XSM）及四波混频（FWM）,可以灵活地组成各种光信号处理器件,如波长变换器、全光触发器、全光逻辑、全光时钟恢复、全光缓存器……等,正成为整个光信号处理的基础。文章介绍了它们的原理和简单应用     

脉冲Nd:YAG激光熔覆修复塑料模具工艺参数的优化

激光器的电压、电流、脉冲宽度、脉冲频率与激光的扫描速度、光斑直径等工艺参数直接影响着脉冲Nd:YAG激光熔覆质量。为了简化工艺调整过程,提出了重叠率的概念,并进行了理论推导,建立了重叠率与脉冲频率、激光扫描速度、激光光斑直径相互关系的方程式。利用预置法在低碳钢基体上熔覆Ni基合金粉末,获得了2组最佳工艺参数,即单脉冲能量、重叠率分别为6.7 J,97.4%和21 J,69.4%。研究表明：在单脉冲能量和重叠率一定的条件下,改变电流、脉宽、脉冲频率及熔覆速度不会影响熔覆质量。