昆虫运动的跟踪技术

昆虫运动的跟踪对跟踪系统提出了特殊的要求。介绍了用来跟踪昆虫飞行的微型线圈跟踪技术、谐波雷达跟踪技术和图像跟踪技术 ,分析比较了它们的特点。     

机动多目标跟踪与被动分辨技术

为了提高多目标跟踪性能，本文结合使用了机动多目标跟踪技术和被动分辨技术。两种方法相互补充可以保证跟踪的连续性，实现很高的目标分辨力。文中对涉及到的算法进行了分析和验证并仿真设计了实现跟踪与被动分辨的显示软件。仿真结果表明，采用此跟踪分辨技术，跟踪结果正确，跟踪轨迹连续。     

基于非线性扩散滤波的双目视觉跟踪与测量研究实现

针对双目视觉跟踪与测量技术的研究主要集中在缩短时间,精确性问题考虑不够充分。结合KAZE特征提取算法,利用卡尔曼预测对目标进行跟踪,提出一种基于图像匹配的双目视觉跟踪与测量算法。将KAZE特征提取算法和SIFT、SURF等算法进行仿真对比,结果表明KAZE算法具有更加出色的匹配率,而跟踪速度相当。运用KAZE算法与卡尔曼预测跟踪技术实现了基于Visual Studio环境下的双目视觉测量与跟踪系统,测试结果表明,该系统可进行有效的高精度测量。     

虚拟产品开发技术（VPD）在光电跟踪仪设计中的应用

从系统工程出发。叙述光电跟踪仪在开发阶段采用VPD(Virtual Product Development)技术实现光电跟踪仪全数字化屏幕样机的方法和过程。介绍光电跟踪仪的组成、原理及设计过程。     

基于LabVIEW的目标跟踪方法设计与实现

针对图像处理技术目标跟踪的特点及技术要求,根据LabVIEW的功能特点及其强大的函数库,提出以LabVIEW为开发环境,利用视觉开发模块,采用图形化、模块化设计思想,为了解决一些文本软件开发方式的可扩展性差、调试困难及可操作性弱的问题,设计实现了一种基于LabVIEW的MeanShift目标跟踪方法;实验结果表明,利用该软件实现的目标跟踪方法运行可靠,易于扩展,便于使用,而且跟踪效果良好,在目标发生旋转、缩放、移动或目标部分遮挡时能够实现很好的跟踪。     

再生反馈技术在跟踪控制系统中的应用

为提高伺服系统跟踪精度，利用现代计算机辅助控制技术，用软件进行坐标变换与反变换、数字计算与滤波和再生补偿量的计算，构成具有再生反馈(近似前馈)的复合控制跟踪系统，最终实现对高速运动目标的高精度跟踪。此技术应用于国家某重点项目中，经过陆地试验和海上试验，充分验证了试验效果很理想。本技术可应用于各种运动目标的跟踪系统中，可有效提高系统跟踪精度。     

光电跟踪仪多传感器数据采集研究

光电跟踪仪数据采集是利用DSP处理技术及多总线结构,实现电视跟踪通道、红外跟踪通道、激光测距机、光纤陀螺仪等多传感器数据的提取,并采用CPCI总线技术结合双端口存储器（双端口RAM）实现系统中信息的快速传输,为光电跟踪仪伺服控制系统提供可靠的数据信息。介绍数据采集系统的设计思想及工作原理,重点研究系统中各传感器的控制方式和接口设计等,并简要说明各系统之间的信息传输方式。     

光电跟踪系统中的惯性稳定技术

在侦查探测、激光通讯等领域,光电跟踪系统的闭环精度是其重要技术指标之一。为了提高闭环精度,一般可使用图像稳定技术,惯性稳定技术或整体自稳定技术。惯性稳定技术因其良好的稳定效果,已在光电跟踪系统中得到广泛应用。采用对比分析的方法对光电跟踪系统中的机架惯性稳定、反射镜惯性稳定以及惯性基准光稳定技术进行了原理分析,优势比较以及发展展望,总结出多种惯性稳定技术交叉使用的复合轴惯性稳定仍是未来一段时间的发展趋势。     

舰载光电系统高精度跟踪控制技术

在舰船摇摆条件下提高光电跟踪系统对目标动态跟踪精度，其控制系统设计的关键技术是隔离扰动和减小高速跟踪时的动态滞后误差。对几种陀螺反馈惯性空间稳定技术进行了详细叙述和对比，得到了采用高测量带宽的陀螺反馈回路可以有效提高系统隔离度，并推导出系统隔离度的计算公式。同时，介绍了计算机辅助跟踪技术的原理以及在陀螺反馈惯性稳定技术的基础上结合计算机辅助跟踪的综合控制技术在舰载光电设备上的应用。以数据说明了这种综合控制技术的有效性和实用性。     

月球目标的探测与跟踪技术研究

研究了月球目标探测成像及自动跟踪系统。利用CCD图像传感器、图像处理技术以及图像跟踪算法可以取代对月球的手动跟踪,无需预知月球的运动轨道,在自动跟踪的同时记录月球影像,便于对月球表面数据的记录和处理,并能进行实时图像处理,利于对月球图像的分析,为月球探测跟踪做了一次有益的新方法尝试。     

TRACKING CONTROL OF THE FLEXIBLE SLIDER-CRANK MECHANISM SYSTEM UNDER IMPACT

The variable structure control (VSC) and the stabilizer design by using pole placement technique are applied to the tracking control of the flexible slider-crank mechanism under impact. The VSC strategy is employed to track the crank angular position and speed, while the stabilizer design is involved to suppress the flexible vibrations simultaneously. From the theoretical impact consideration, three approaches including the generalized momentum balance (GMB), the continuous force model (CFM), and the CFM associated with the effective mass compensation EMC are adopted, and are derived on the basis of the energy and impulse-momentum conservations. Simulation results are provided to demonstrate the performance of the motor-controller flexible slider-crank mechanism not only accomplishing good tracking trajectory of the crank angle, but also eliminating vibrations of the flexible connecting rod.     

电视跟踪在光电火控系统中的应用及发展趋势

电视跟踪在各种武器系统中得到越来越广泛应用。根据电视跟踪的工作原理和特点,论述电视跟踪在光电火控系统中的应用。分析国内外技术水平,并对其发展趋势进行了展望。     

Towards dynamic structure of biological complexes at atomic resolution by cryo-EM

Cryo-electron microscopy makes use of transmission electron microscopy to image vitrified biological samples and reconstruct their three-dimensional structures from two-dimensional projections via computational approaches. After over40 years of development, this technique is now reaching its zenith and reforming the research paradigm of modern structural biology. It has been gradually taking over X-ray crystallography as the mainstream method. In this review, we briefly introduce the history of cryo-EM, recent technical development and its potential power to reveal dynamic structures. The technical barriers and possible approaches to tackle the upcoming challenges are discussed.     

Geometrical optics-based ray field tracing method for complex source beam applications

Due to the fact that traditional ray field tracking approaches require a large number of geometrical optical(GO) ray tubes,they are very inefficient in many practical applications.An improved ray model scheme for a complex source beam(CSB) tracking technique is proposed in this paper.The source field can be expressed by a superposition of CSBs,then every CSB basis function has a Gaussian-type amplitude distribution and is suitable for replacing a GO ray tube in the ray tracing approach.The complex phase matching technique is adopted to find the reflected beam in the reflection point where local approximation is used to represent the curved surface in its neighborhood.A new solution to multiple reflections using the conventional right-handed reflected system is used to track the field easily.Numerical results show the accuracy of the proposed method.     

光电图像自动识别跟踪技术

概述自动目标识别的军事应用,论述光电混合实时光学相关器算法和实时器件,并介绍光电图像自动跟踪技术的发展情况。     

光电精确制导战术武器的发展

本文简述光电精确制导技术武器发展的基本特征，探讨新一代自动寻的精确制导战术武器发展的趋势和技术途径，分析精确制导战术武器的关键技术。     

A noise cross PSD estimator based on improved minimum statistics method for two-microphone speech enhancement dedicated to a bilateral cochlear implant

Coherence based methods have been successfully applied to dual-microphone noise reduction systems. These techniques showed good results when noise signals on two microphones were uncorrelated, but their performance decreased with correlated noises. It could be improved when the cross power spectral density (CPSD) of received noises is available.In this paper, an improved minimum tracking (IMT) technique for noise CPSD estimation was proposed. The performance of this technique was compared to two other noise CPSD estimators based on voice activity detection (VAD) and minimum tracking (MT) approaches. Evaluation was performed at four signal-to-noise ratios (SNR) and two interfering noise source configurations.Results showed a superiority of the IMT approach in terms of low computing time and quality indicated by the perceptual evaluation of speech quality (PESQ) scores. Then, subjective listening tests were carried out with 50 normal hearing listeners using a specific bilateral cochlear implant (BCI) simulator and utilizing the French Lafon database corrupted by additional babble noise. Results obtained with the proposed technique were better than the two previously mentioned noise CPSD estimators.     

航空光电侦察技术发展研究北大核心CSCD

航空光电侦察具有隐蔽性强、直观性好、分辨率高等优点,一直是各国军事侦察的重要手段。根据作战任务需求,将航空光电系统分为凝视观瞄、情报侦察监视、红外搜索与跟踪、告警与对抗四大类。列举了典型产品,分析其特点及技术途径,从光学实现、稳定平台演进、瞄准线稳定、态势感知、轻量化、多任务协同、开放式系统架构(open systems architecture, OSA)等多方面分析国内外航空光电侦察技术和装备的发展情况及趋势。     

ON FEEDBACK CONTROL OF DELAYED CHAOTIC SYSTEM

In this paper two different types of feedback control technique are discussed: the standard feedback control and the time-delay feedback control which have been successfully used in many control systems. In order to understand to what extent the two different types of control technique are useful in delayed chaotic systems, some analytic stabilization conditions for chaos control from the two types of control technique are derived ased on Lyapunov stabilization arguments. Similarly, we discuss the tracking problem by applying the time-delay feedback control. Finally, numerical examples are provided.     

Intersubject variability in the analysis of diffusion tensor images at the group level: fractional anisotropy mapping and fiber tracking techniques

Introduction

Diffusion tensor imaging (DTI) provides comprehensive information about quantitative diffusion and connectivity in the human brain. Transformation into stereotactic standard space is a prerequisite for group studies and requires thorough data processing to preserve directional inter-dependencies. The objective of the present study was to optimize technical approaches for this preservation of quantitative and directional information during spatial normalization in data analyses at the group level.

Methods

Different averaging methods for mean diffusion-weighted images containing DTI information were compared, i.e., region of interest-based fractional anisotropy (FA) mapping, fiber tracking (FT) and corresponding tractwise FA statistics (TFAS). The novel technique of intersubject FT that takes into account directional information of single data sets during the FT process was compared to standard FT techniques. Application of the methods was shown in the comparison of normal subjects and subjects with defined white matter pathology (alterations of the corpus callosum).

Results

Fiber tracking was applied to averaged data sets and showed similar results compared with FT on single subject data. The application of TFAS to averaged data showed averaged FA values around 0.4 for normal controls. The values were in the range of the standard deviation for averaged FA values for TFAS applied to single subject data. These results were independent of the applied averaging technique. A significant reduction of the averaged FA values was found in comparison to TFAS applied to data from subjects with defined white matter pathology (FA around 0.2).

Conclusion

The applicability of FT techniques in the analysis of different subjects at the group level was demonstrated. Group comparisons as well as FT on group averaged data were shown to be feasible. The objective of this work was to identify the most appropriate method for intersubject averaging and group comparison which incorporates intersubject variability of the directional information.