简易无源定位雷达技术

针对静默哨兵系统等隐身雷达的战场机动能力不足,提出了一种便携式无源侦察系统的设计方法。通过三点布站对目标测距定位,对信号作相关处理,提高侦测距离,用时域遍历代替相控天线在空域遍历实现多目标功能。计算结果表明,最大侦测距离可达70 km,最多可同时探测20个目标。方法简洁,造价低廉,对构建国土和城市重点防御有一定参考价值。     

非协同目标识别技术的研究进展

非协同目标识别技术是识别领域研究的新课题,它通过处理侦测到的目标物理特征来实现对目标身份的识别。该技术可提供更全面、更完善的战场目标信息,有助于作战人员及时掌握战场态势、减少友军误伤。从目标识别的基础理论开始,介绍了几种适合非协同目标识别的融合方法及其改进措施,总结了目前非协同目标识别技术研究的主要进展,即采用基于统计推理的数据融合技术,对多个传感器侦测的目标特征信息进行处理,实现了对属性、类型、型号、作战意图及威胁程度等目标信息的判定和分析。同时,指出国外一些使用数据融合技术的武器装备已具备对多个非协同目标的识别能力和战场信息感知能力。最后,提出了今后的研究方向。     

便携式无源探测雷达研究

针对静默哨兵系统等隐身雷达的战场机动能力不足,提出了一种便携式无源侦察系统的设计方法.通过三点布站对目标测距定位,对信号作相关处理提高侦测距离,用时域遍历代替相控天线在空域遍历实现多目标功能.方法简洁、造价低廉,对构建国土和城市重点防御有一定参考价值.     

激光主动侦测系统探测能力分析

激光主动侦测系统可实现远距离猫眼目标的成像探测与识别,探测能力分析是系统设计的前提和基础.为了评估激光主动侦测系统对猫眼目标的探测能力,以激光回波功率为基础,建立了系统信噪比的数学物理模型.分析了影响探测能力的因素,数值模拟了信噪比与接收光学镜头直径、发射激光峰值功率、激光束散角以及等效反射面离焦量的定量关系.结果表明,在一定作用距离范围内,散粒噪声、背景噪声与暗电流噪声、热噪声相差至少2个数量级,系统噪声主要来源于散粒噪声及背景噪声;提高系统探测能力最为有效的方法是选用激光束散角小的光源.这一结果可用于指导激光主动侦测系统的设计.     

红外空域弱小目标探测系统中恒虚警技术研究

对空域中弱小目标的探测是红外成像防御与制导的关键技术。由于空域中弱小目标距离较远,在红外探测器上呈现为无纹理特征的弱小点。由于红外探测器噪声与视场中杂波干扰,很难将目标从红外图像中提取出来。在红外空域弱小目标探测系统中,虚警率与探测率是一对矛盾的概念。针对这一问题提出了一种基于杂波模型估计理论的恒虚警(CFAR)检测技术。该CFAR技术是建立在对红外图像背景杂波分析建模的基础上,根据Neyman-Pearson准则设计CFAR检测器,实现在恒定虚警的前提下最大化追求系统的探测率,以此提高红外空域弱小目标探测系统的探测距离和目标识别能力。     

一种基于深度特征的信号分类方法

针对实际侦测辐射源目标信号交叠、参数灵活多变、波形不完整等特点,以及传统目标分类识别方法准确率不高的问题,提出了一种基于深度特征的信号分类方法.通过数据积累对全脉冲数据进行补全、纠错,综合时域、频域、空域、能量域、调制域等多域参数提取隐藏特征,搭建深度学习网络对侦测数据进行持续训练,实现对复杂目标信号的分类.     

基于卡尔曼预测采样与空域图描述的稳健红外目标跟踪

目标状态采样策略和观测概率模型是影响粒子滤波理论框架下红外目标跟踪性能的主要因素.为了提高红外目标跟踪性能,介绍了一种基于卡尔曼预测采样与空域图描述的红外目标跟踪方法.目标状态采样采用卡尔曼预测采样策略,通过卡尔曼预测过程将目标的观测信息组合到重要性建议分布;采用空域图技术实现红外目标的稳健描述,通过计算参考目标的空域图与目标样本的空域图之间的Bhattacharyya距离,建立观测概率模型.传感器自运动场景、辐射不稳定场景及海杂波背景下的红外目标跟踪实验证明:该方法是有效的和稳健的.     

自由曲面数字化测量中黏性目标识别技术研究

自由曲面数字化测量中,由于传感器单元测量区域较小或被测物体本身遮挡等特性的限制,实现整体测量需要进行多次的图像拼接。黏性目标的应用较好地解决了空间图像拼接中不同坐标系的转换与统一。提出了一种基于不变曲线矩法对多重圆弧平面型黏性目标进行识别的技术。这种方法可以准确地对黏性目标进行识别,同时具有较强的鲁棒性。根据这种方法实现的三维空间距离测量相对误差优于0．6％。     

奇妙的飞思卡尔TM加速度传感器

加速传感器工作原理及架构飞思卡尔传感器产品主要分为三大部分:惯性传感器、压力传感器与安全和报警IC。其中,惯性传感器即为加速传感器,可以用于侦测倾斜、振动及撞击,因此可以用在汽车乘客安全、振动监控、运动诊断、防盗装置、电器平衡、地震检测、倾角／倾斜仪及便携式电子设备中。     

岸基雷达的海杂波特性及抑制方法研究

岸基雷达在执行具体任务的过程中,常常会受到海杂波的干扰,从而降低其侦测能力。由于海杂波的变化无明显规律且性质难以掌控,因此其消除工作也比较困难。海杂波和海域、气象等各种因素都有关系,当海杂波不存在时,雷达画面比较清晰,而受到海杂波干扰后,往往会令雷达无法对目标进行准确的定位与侦测。本文从海杂波特性入手,从时域、空域、频域三个方面提出了海杂波的消除方法。     

An Unsupervised Classification for Fully Polarimetric SAR Data Using SPAN/H/ IHSL Transform and The FCM Algorithm

 In this paper, the IHSL transform and the Fuzzy C-Means (FCM) segmentation algorithm are combined together to perform the unsupervised classification for fully polarimetric Synthetic Ap-erture Rader (SAR) data. We apply the IHSL colour transform to space to obtain a new space (RGB colour space) which has a uniform distinguishability among inner parameters and contains the whole polarimetric information in Then the FCM algorithm is applied to this RGB space to finish the classification procedure. The main advantages of this method are that the parameters in the color space have similar interclass distinguishability, thus it can achieve a high performance in the pixel based segmentation algorithm, and since we can treat the parameters in the same way, the segmentation procedure can be simplified. The experiments show that it can provide an improved classification result compared with the method which uses the space di-rectly during the segmentation procedure.     

AN UNSUPERVISED CLASSIFICATION FOR FULLY POLARIMETRIC SAR DATA USING SPAN/H/α IHSL TRANSFORM AND THE FCM ALGORITHM

In this paper, the IHSL transform and the Fuzzy C-Means (FCM) segmentation algorithm are combined together to perform the unsupervised classification for fully polarimetric Synthetic Ap-erture Rader (SAR) data. We apply the IHSL colour transform to H/α/SPANspace to obtain a new space (RGB colour space) which has a uniform distinguishability among inner parameters and contains the whole polarimetric information in H/α/SPAN.Then the FCM algorithm is applied to this RGB space to finish the classification procedure. The main advantages of this method are that the parameters in the color space have similar interclass distinguishability, thus it can achieve a high performance in the pixel based segmentation algorithm, and since we can treat the parameters in the same way, the segmentation procedure can be simplified. The experiments show that it can provide an improved classification result compared with the method which uses the H/α/SPANspace di-rectly during the segmentation procedure.     

Cryptographic distinguishability measures for quantum-mechanicalstates

This paper, mostly expository in nature, surveys four measures of distinguishability for quantum-mechanical states. This is done from the point of view of the cryptographer with a particular eye on applications in quantum cryptography. Each of the measures considered is rooted in an analogous classical measure of distinguishability for probability distributions: namely, the probability of an identification error, the Kolmogorov distance, the Bhattacharyya coefficient, and the Shannon (1948) distinguishability (as defined through mutual information). These measures have a long history of use in statistical pattern recognition and classical cryptography. We obtain several inequalities that relate the quantum distinguishability measures to each other, one of which may be crucial for proving the security of quantum cryptographic key distribution. In another vein, these measures and their connecting inequalities are used to define a single notion of cryptographic exponential indistinguishability for two families of quantum states. This is a tool that may prove useful in the analysis of various quantum-cryptographic protocols     

基于Gabor函数能量特征的指纹增强

指纹图像增强技术可以有效地加强指纹的脊线特征,为指纹细节的提取和匹配奠定可靠的基础,直接影响指纹识别的识别率和识别速度.用Gabor函数变换将空域的指纹图像变换到联合空间频率域,并将联合空间频率域的能量分布作为指纹的特征.Gabor函数滤波器在频域内对子块其主方向上频率能量分布进行高分辨率滤波,进行了识别匹配.实验表明...     

时频空交叠信号的脉内调制类型识别算法

复杂电磁环境下的雷达信号分选技术充分利用被侦察信号的特征信息,把分属于不同信号源的雷达脉冲流分离开来。随着脉冲流密度的增加,出现了一些在时频空3个维度上均严重交叠的脉冲,这些脉冲的辐射源信息差别很小,以至于识别算法无法正确将它们区分,进而造成脉冲丢失或错误识别,使得信号分选的性能大大下降。以6种常见的脉内调制类型脉冲为研究对象,针对脉冲之间两两交叠的情况,提出了基于部分快速傅里叶变换算法的时频空交叠信号脉内调制类型识别算法,并通过一系列仿真分析了算法的性能,证明了算法能够有效地分辨频域和空域高度重叠但时域不完全重叠的信号脉冲流,提高信号分选的性能。     

情感识别中的迁移学习问题综述

情感识别是实现自然人机交互的必要过程。然而,情感数据高昂的采集和标注成本成为了限制情感识别研究发展的一大瓶颈。在无标注或有限标注的场景下,利用知识的跨领域或跨任务迁移提升情感识别效果的问题值得探索。本文对情感识别中的迁移学习问题进行了梳理和分析。首先,将迁移学习问题划分为针对领域差异和针对任务差异的两大部分,并进一步将每部分问题细分为多种不同的情况。随后,基于情感识别领域的研究现状,分别总结不同情况下的现有工作。在目标领域训练资源匮乏的情况下,可以利用其他带标注的数据集作为源领域训练模型,并对齐不同领域下的特征分布,或将特征映射到域间共享的空间。考虑到情感标签所提供的监督信息往往较为有限,为了进一步提升模型的识别效果,可以引入其他相关任务进行联合训练,或将预训练模型、外部知识库提供的先验语义知识迁移到情感识别任务中。最后,讨论了情感识别领域中未来需要得到更多关注和探索的迁移学习问题,旨在为研究者带来新的启发。     

A novel zero-watermarking scheme with enhanced distinguishability and robustness for volumetric medical imaging

The authenticity and copyright protection of volumetric medical images has become extremely important when these images are distributed online for diagnosis and education purpose. Compared to the authenticity and copyright protection of conventional images, there are two additional challenges for protecting the volumetric medical images. On one hand, the content of the protected medical images must be distortion-free to ensure unbiased diagnosis. On the other hand, it requires enhanced distinguishability to avoid misclassification of non-protected images into the protected set because volumetric medical images of different persons in the same modality share similar visual structures. To address these issues, a novel multi-slice feature based zero-watermarking scheme with enhanced distinguishability and robustness for volumetric medical imaging is proposed. In this scheme, ring statistics are deployed to guarantee both the watermarking distinguishability and robustness. In addition, an intra-slice variation based mechanism is designed to further enhance the watermarking distinguishability. Finally, a logistic-logistic system based chaotic map is used to ensure the watermarking security. Our experimental results demonstrate that the proposed scheme not only satisfies the lossless quality requirement but also ensures the watermarking distinguishability and robustness, which outperforms the state-of-the-art schemes.     

Diagnosability and Distinguishability Analysis and Its Applications

As systems become more complex, it becomes necessary to understand, simplify, and apply fault diagnosis and fault-tolerant design. Although some graph-theoretical diagnostic models such as self-diagnosis model have been studied, the model can not be applied to most systems due to the assumption that each unit has its own testing capability. This paper presents a graph-theoretical diagnosis model expressed by a set of fallible units, a set of measurements, and an incident matrix indicating binary relation between these two sets. Since this model explicitly separates tested units (fallible units) and testing units (measurements), we can discuss diagnostic aspects from both sides. Diagnosability and distinguishability of the model with multiple faults are discussed from combinatorial point of view. Measures of t-fault diagnosability and t-out-of-s diagnosability which was introduced on the self-diagnosis model are discussed. Conditions for these diagnosabilities are expressed by a topological concept of fault distance. The concept of distinguishability is generalized to multiple fault situations called t-fault distinguishability. A lower bound for the distinguishability is obtained by using fault distance. The new concept of s-distinguishability class (s-dc) is presented. This analysis is recommended in the design of systems to attain a required level of diagnosability and distinguishability as well as in the analysis of present systems to investigate their diagnostic aspects. Two application examples are presented: Diagnosability and distinguishability analysis of error-correcting codes, and design of instrumentation systems of large plants with a required level of diagnosability.     

不同光源对激光尘埃粒子计数器性能的影响

使用Beam Profile2350光束诊断仪测量了氦氖激光和半导体激光两种典型光源的光束特性,并分析了将它们作为激光尘埃粒子计数器的光源时,其在光敏区所产生光场的不均匀性。同时讨论了光场不均匀对计数器性能的影响,计算了两种不同光源下,计数器计数效率和分辨比率的差异。结果表明,以半导体激光作为计数器光源时,光敏区的光强均匀性更好,计数效率更高,粒径的分辨比率较氦氖激光作用时提高了17％,增大了粒径的有效测量范围。     

图像过完备稀疏表示理论及应用综述

超完备字典稀疏表示作为一种有效表示模型,广泛应用于各种信号和图像处理任务中。介绍了稀疏表示的理论框架以及主要研究方向,分别从稀疏表示的可重构性和区分性两方面对其在图像处理及图像分析领域的应用进行综述。