光谱成像技术在海上目标探测识别中的应用探讨

光谱成像可同时获得光谱和空间信息,这使得光谱成像技术在解决复杂海洋环境背景下目标探测与识别时表现出独特的优势,已成为光电目标检测领域的一个前沿研究方向。对光谱成像技术的原理、特点进行了讨论并重点列举了该技术在探测领域的应用;介绍了光谱成像技术在海上目标探测识别中的研究进展,并对光谱成像技术在该领域的应用价值进行了探讨。     

基于Matlab与VC的WSN定位跟踪仿真平台

无线传感器网络(WSN)是目前信息科学和通信技术领域的一个研究热点。目标定位跟踪是WSN的一项基本功能,在军事和民用领域都具有广泛的应用前景。但目前常用基于目标跟踪的实验仿真平台还不够完善,因此,本文主要研究了Matlab与VC的混合编程接口实现,实现在VC环境中的WSN实验仿真平台,为后续WSN定位跟踪研究提供保障。     

偏振成像探测技术发展现状及关键技术

考虑偏振成像探测技术在目标探测中具有独特优势,本文介绍了偏振成像探测技术的概念,概括了国外偏振成像探测技术的研究历程和发展现状。基于上述描述,针对偏振成像探测的关键技术进行了深入的讨论,包括目标偏振特性、信道环境下的偏振传输特性和偏振成像目标全偏振图像的获取等。最后总结了该研究领域存在的主要问题,归纳了偏振成像探测技术的发展趋势。     

听觉外周计算模型研究进展

在简单介绍听觉外周特性之后,对近30年听觉外周计算模型的研究及其在语音识别领域的应用进行了评述,针对未来语音信号处理领域中听觉外周的建模,提出了一些设想；讨论了在被动声呐目标识别任务中应用听觉模型的可能性,同时,结合声呐目标识别的特点,对听觉外周模型的适用性建模研究,提出了若干建议。     

基于K-粒子滤波和边缘检测的图像目标跟踪研究

图像目标跟踪是根据图像序列探测和跟踪某个目标,在军事目标的探测与跟踪、安全保护监控、城市与高速公路的交通监测等许多领域有着重要的应用.首先基于背景减图像分割,提出了一种有效的图像边缘检测方法,检测感兴趣的运动图像目标;其次提出了改进的最近邻域数据关联方法和K-粒子运动图像目标估计方法;最后以一个多行人的图像目标为例,对上述方法进行了仿真研究.仿真结果表明了上述方法的有效性和较高的跟踪精度.     

希格斯玻色子找到后,美国物理学家在想些什么

<正>科学家在想什么"科学家在想什么"是本刊在专家的建议下开辟的新栏目,将不定期刊出。本栏目试图通过介绍科学家对自身研究领域的关注热点、研究计划、研究目标及其对研究前景的展望,来提升读者对相关科学领域的认知高度和深度。希望有关专家、学者踊跃投稿,以保证此栏目繁荣。     

基于ACE算法的高光谱隐蔽目标探测

隐蔽目标的探测一直都是军事上重点研究的领域,随着高光谱成像技术的发展,为这一领域提供了新的解决思路。利用高光谱数据高的谱间分辨率,可在某些波段实现对隐蔽目标和背景的光谱区分,提出了一种基于ACE(alternation conditional expectations)算法高光谱隐蔽目标探测技术,充分利用背景和隐蔽目标在不同波段光谱不同的特点,引入光谱重排技术和一阶微分技术,使得背景光谱出现振荡,从而提取出目标。相较其他算法,该文提出的算法提取精度高、虚警率低,实现了较好的隐蔽目标探测效果。     

空间目标光谱实测技术与表面材料分析研究

随着航天活动的日益增加,空间碎片的数量急剧增多,对未知空间碎片进行编目和识别显得尤为重要。由于火箭箭体、人造卫星及其裂解碎片等在空间中处于外表裸露状态,其表面材料的物理与化学特性会产生较大变化。目前,针对空间目标表面材料的研究主要集中在地面实验室,无法对其在深空中的状态变化进行准确判断。利用空间目标光电望远镜及光谱测试终端组合,可以实时地对空间目标的光谱特性开展研究,进一步探究材料特性变化对目标特性识别的影响。通过利用长春人卫站1.2 m空间目标光电望远镜及相关光谱测试终端,同时结合图像预处理软件获取空间目标的高光谱图像,进一步运用天文学方法IRAF提取光谱一维数据,得到可分析数据。通过偏最小二乘法反演分析表面材料的面积比、置信度。实验将6个空间目标光谱数据分别进行反演,通过6种常用航空材料的反演结果显示所有目标均可解析出至少两种材料,其共同反演出现金色保温膜,它是空间目标表面一定含有的材料之一,其所占表面积比例也较高,结果分别约为0.75,0.78,0.78,0.59,0.71和0.45。其中,4个目标反演出现碳纤维板,结果分别约为0.19,0.22,0.07和0.24;3个目标反演出现砷化镓,结果分别约为0.07,0.15和0.17;2个目标反演出现Si,结果分别约为0.29和0.55。并且置信度分别约为84.7%,80.4%,84.1%,82.8%,82.6%和79.6%。实验结果表明观测方法可信性更高,在空间目标领域的观测技术、获取数据、研究分析等方面的研究结果对后续深入探索具有参考作用。实验结果和空间目标来源自洽度高,研究方法简单易行且与传统光学观测兼容性好。该方法拓展了精密跟踪型空间目标观测的研究领域,不仅具有目标所在空间环境分析的科学意义,也具有空间目标运行安全的应用前景。     

遥感遥测中偏振信息的研究进展

偏振是光的固有特性之一。地球表面和大气中的任何目标物在与光相互作用的过程中,由于目标物的表面结构、内部结构以及光入射的角度不同,都会产生其自身性质决定的特征偏振。而偏振遥感探测就是以目标物辐射能量的偏振特征作为探测信息,可以在复杂的背景中提取目标的七维信息并很好地分辨目标物上低反射区域和目标轮廓,解决了传统遥感所不能解决的大气探测和伪装识别方面的问题,具有良好的应用前景。文章介绍了偏振遥感遥测的机理,详细阐述了偏振探测的理论模拟、偏振遥感探测仪以及偏振遥感探测技术在大气探测、地球资源探测、海洋表面与水下探测、生物医学、天文探测、军事等领域应用的国内外研究概况、水平和发展趋势,归纳了目前存在的问题,并指出目前国内外偏振探测技术的研究方向,以期为后续的同类研究提供参考。     

角反射体RCS微波暗室测量及分析

角反射体雷达散射截面(RCS)的测量是雷达目标识别、成像等研究领域的一个关键环节;在对目标RCS测量原理分析的基础上,介绍了一个在微波暗室中基于紧缩场和矢量网络分析仪测量目标RCS的测量系统;利用该系统对角反射体垂直姿态和45°姿态的RCS进行了360度转角扫频的测量,结果与FEKO软件仿真计算的结果对比表明,两种方法得到的数据走势基本一致。     

等离子体微带开关特性

提出一种基于微放电等离子体的微带开关。它是以“时变等离子体”取代微带线射频微机电开关的“金属悬臂”,利用等离子体的导体或介质特性使电磁波沿其表面进行传输或截止,从而实现微带线上电磁波传输的动态控制。等离子体微带开关的基本结构包括用以隔断电磁波的微带间隙和产生片状等离子体的放电装置。放电产生时,电磁波因等离子体导体性通过开关,形成“开”状态;放电停止后,电磁波被微带间隙反射,形成“关”状态。利用CST软件仿真研究了等离子体开关特性,结果表明:这种开关的带宽由等离子体密度决定,隔离度由间隙决定,而工作插损与等离子体密度和电子碰撞频率有关。等离子体位形（宽度、厚度等）对于开关性能也非常重要。     

Multi-step phase-shifting algorithms insensitive to linear phase shift errors

We describe and analyse a group of multi-step phase calculation algorithms for evaluation of interferometric measurements using the phase-shifting technique. Phase-shifting algorithms are proposed, with a constant but arbitrary phase shift between captured frames of the irradiance of the interference field. The algorithms are similarly derived as so called Carré algorithm. The phase evaluation process is not dependent on linear phase shift errors. An advantage of the described algorithms is their ability to determine the phase shift value at every point of the detector plane. Moreover, a complex error analysis of proposed algorithms is performed and the algorithms are compared to several common error compensating phase stepping algorithms.     

Error-Compensating Phase Measuring Algorithms in a Fizeau Inter ferometer

In phase-shifting Fizeau interferometers, nonlinear motion of the phase shifter and multiple-beam interference are the most common sources of systematic errors affecting high-precision phase measurement. A new class of algorithms with extended compensating capability for these errors is proposed. Measurement errors for the new algorithms and two groups of conventional algorithms: discrete Fourier algorithms and the Schwider-Larkin-Hibino algorithms are estimated as a function of the number of sampled images when these systematic error sources are equally dominant. It is shown that the conventional phase-measuring algorithms produce significant errors when the reflectivity of the testing surface exceeds ten percent. Also, these algorithms have an optimum number of samples at around seven with which the residual errors become minimum. The new class of algorithms shows a substantial reduction of the residual errors when the number of samples exceeds ten. There is no optimum number of samples for the new algorithms. For fewer than six samples, discrete Fourier algorithms which have no error-compensating capability for the nonlinearity of phase modulation give a minimum error.     

图像旋转算法的分析与对比

为提高图像旋转补偿算法的效率,需要研究合理的空间变换方法,通过分析直接法、三步法和累加法的基本原理和计算复杂性,比较了三种方法的计算效率.实验表明,累加法减少了图像旋转中大量的浮点运算以及取整运算,可以在保证旋转质量的前提下,使图像旋转的平均处理速度明显提高.     

Five-step phase-shifting algorithms with unknown values of phase shift

The presented work offers new algorithms for phase evaluation in interferometric measurements. Several phase-shifting algorithms with an arbitrary but constant phase-shift between captured intensity frames are proposed. These phase calculation algorithms need to measure five frames of the intensity of the interference field. The algorithms are similarly derived as so called Carré algorithm. The phase evaluation process then does not depend on the linear phase shift errors. Furthermore, the detailed analysis of the algorithms with respect to most important factors, which affect interferometric measurements, is carried out. It is also studied the dependency of the evaluation algorithms on the phase shift values, and the proposed phase calculation algorithms are compared with respect to the resulting phase errors. The influence of most important factors in the measurement and evaluation process was simulated as systematic and random errors using a proposed mathematical model.     

Detection and tracking of targets in infrared images using Bayesian techniques

Simple yet robust techniques for detecting targets in infrared (IR) images are an important component of automatic target recognition (ATR) systems. In our previous works, we have developed IR target detection and tracking algorithms based on image correlation and intensity. In this paper, we discuss these algorithms, their performances and problems associated with them and then propose novel algorithms to alleviate these problems. Our proposed target detection and tracking algorithms are based on frequency domain correlation and Bayesian probabilistic techniques, respectively. The proposed algorithms are found to be suitable for real-time detection and tracking of static or moving targets, while accommodating for detrimental affects posed by the clutter and background noise. Finally, limitations of all these algorithms are discussed.     

Symplectic Runge-Kutta and related methods: recent results

Symplectic algorithms are numerical integrators for Hamiltonian systems that preserve the symplectic structure in phase space. In long time integrations these algorithms tend to perform better than their nonsymplectic counterparts. Some symplectic algorithms are derived by explicitly finding a generating function. Other symplectic algorithms are members of standard families of methods, such as Runge-Kutta methods, that just turn out to preserve the symplectic structure. Here we survey what is known about the second type of symplectic algorithms.     

孤立波方程的保结构算法

讨论了孤立波方程的保结构差分算法，以一些经典的孤立波方程为例，如KdV，sine-Gordon，K-P方程，给出了它们的辛和多辛结构，说明辛和多辛算法的可适用性．提出局部守恒算法和广义保结构算法的概念，它们是保结构算法的概念自然推广．还给出一种能系统构造局部守恒格式的复合方法．数值例子说明，保结构数值能很好模拟各种孤立波的演化。     

图像增强算法综述

图像增强算法能够提高图像整体和局部的对比度,突出图像的细节信息,使增强后的图像更符合人眼的视觉特性且易于机器识别,在军事和民用领域具有广泛的应用。本文从图像增强算法的原理出发,归纳总结了近年来应用比较广泛的4类图像增强算法及其改进算法,包括直方图均衡图像增强算法、小波变换图像增强算法、偏微分方程图像增强算法和基于Retinex理论的图像增强算法。结合人眼视觉特性、噪声抑制、亮度保持和信息熵最大化等图像增强的改进算法,在保证增强图像具有较高对比度的前提下,可进一步提升图像的质量。实现了9种较为典型的图像增强算法,采用主观和客观的评价方法对增强效果进行了对比,分析了不同增强算法的优缺点,并给出了这些算法的计算时间。对这些算法的深入研究能够推动图像增强技术向更高水平发展,从而使图像增强技术在多个学科领域发挥重要作用。     

Static and dynamic routing and wavelength assignment algorithms for future transport networks

In this paper, two static and three dynamic routing algorithms have been proposed and compared to some of the existing algorithms on the basis of blocking probability. The two proposed static routing and wavelength assignment (RWA) algorithms reduce the blocking probability to maximize the utilization of network. For dynamic algorithms, first a model with no weights assignments is presented and then three algorithms are proposed and analysed with weight assignment resulting in reduction of blocking probability. All these algorithms are analysed and compared with four wavelength assignment schemes which are first-fit, random, most used and least used. It is shown that our proposed static algorithms give the best performance for first-fit wavelength assignment and most used wavelength assignment strategies with reduced complexity. For least used wavelength assignment and random wavelength assignment, 1 fixed and 2 alternate routing algorithm gives the lowest blocking probability. For dynamic routing, it has been shown that our proposed algorithm “less weight to maximum empty and nearest” gives the least blocking probability as compared to the other dynamic routing algorithms for random, most used and least used wavelength assignment strategies.