基于改进欧几里得算法的卷积码快速盲识别算法

卷积码盲识别技术在信号截获、智能移动通信、多点广播通信等领域具有广泛应用,针对卷积码的快速盲识别问题,对经典欧几里得算法进行了改进,提出了一种基于改进欧几里得算法的卷积码的快速盲识别方法。算法对卷积码码率进行遍历,通过欧几里得迭代算法求解卷积的校验多项式,实现了任意码率卷积码的快速盲识别。对算法进行了仿真,仿真结果验证了算法的有效性,且算法的计算量小于文献中已有算法。     

矩阵变换特征与码序列联合学习的卷积码识别方法

现有基于深度学习的卷积码识别方法仍存在参数规模较大、识别性能较弱等不足。针对该问题,提出了一种基于矩阵变换特征与码序列联合学习的卷积码识别方法。将接收到的码字序列排列成矩阵形式,利用软信息剔除可靠性较低的码字,通过一种新的矩阵变换算法得到特征矩阵。在识别时,将原始码字矩阵和特征矩阵输入到具有多模态数据联合学习能力的网络模型,在神经网络中完成特征的提取融合与卷积码的识别。仿真结果表明,所提方法性能明显优于现有基于深度学习的识别方法,特别是对于高码率卷积码;当码率较低时,同样优于传统识别方法。当信噪比达到5 dB时,25种不同参数卷积码的识别率均可达到100%。     

一种雷达辐射源识别自学习算法研究

针对目前雷达对抗系统面临的辐射源识别精度不高、智能化水平低的特点,将自学习理论引入到雷达对抗系统中。提出了基于遗传算法(GA)的自学习算法实现雷达辐射源智能识别的方法。实验表明:在使用相同的特征参数"前件"条件下,通过这种自学习方法得到的正确识别率高于其它识别方法。     

一种RS码快速盲识别方法

为了获取数字通信中未知线路的纠错编码信息,提出了一种RS码快速盲识别方法.通过对RS码的二进制表示进行码根求解的方法来检测未知线路的RS码长、本原多项式阶数以及可能的本原多项式;进而遍历得到的本原多项式对RS序列进行伽罗华域的傅里叶变换(GFFT),通过连零位置和个数最终确定未知线路的真实本原多项式和生成多项式.实验验...     

点数任意时的快速插值算法

本文建立了运算量级为O(nlog_2m) 的多项式快速除法(其中,m,n分别为除式与被除式的多项式次数),把点数n+1为2的幂次的多项式快速插值推广到n+1为任意数情形,提出了运算量级为O (n log_2~2n) 的快速插值算法。     

利用单位矩阵求有解线性方程组

将n行m列矩阵A与n阶单位矩阵E联合组成一个矩阵(AE)。对矩阵(AE)的行施行初等变换变为矩阵(—AE)。可以看出：—A是距阵A施行该变换的结果；-E是矩阵E施行该变换的结果并且还有以下结论存在：     

m 序列完备递归采样值的存在条件

本文用群论方法讨论了n级m序列完备递归采样值的存在条件,证明了对任意n级m序列,其完备递归采样值存在的充要条件是商群G=Z_p~*/H(其中p=2~n—1,Z_p~*={s|(s,p)=1},H={1,2,2~2,…,2~(n-1))为循环群。在完备递归采样值存在的条件下,求出了完备递归采样值的个数为n.φ(φ(2~n—1)/n)。最后给出了递归采样值的一个重要性质。     

滚动轴承含噪声谐波信号的欠确定盲源分离方法研究

目前使用的大多数盲源分离方法都依赖于观测传感器数量大于或等于信号源数目这样一个基本假设。算法主要针对传感器数量m小于源信号数量n(欠确定)情况下旋转机械含噪声谐波信号的盲源分离问题展开研究。它在输入信号频域稀疏性假设和源信号之间线性混合假设的前提下,提出了一种势函数聚类的源数目估计方法,并对通道衰减和延时进行了计算。实验信号仿真结果证明了该方法的可行性和可靠性。     

两向二维NFA及其在SAR目标识别中的应用

通过对传统线性鉴别分析局限性的分析,提出一种基于两向二维非参数特征分析((2D)2NFA)的SAR图像目标识别方法,该方法有效克服了线性鉴别分析的固有缺陷并且运算量也大大降低。首先,定义一种图像矩阵的近邻样本选取方法,继而利用k近邻样本构造(2D)2NFA的类间散度矩阵和类内散度矩阵,然后使用(2D)2NFA提取样本的特征,最后在特征空间中使用简单的最近邻分类器进行待识别测试目标的分类识别。用美国运动和静止目标获取与识别(MSTAR)计划录取的SAR图像数据进行了仿真实验,实验结果表明(2D)2NFA增强了提取特征的可鉴别性,能够获得更高的识别率,而且减小了特征维数。     

基于神经网络的分段供电驱动脉冲信号识别方法

针对分段供电驱动信号的质量评价与边界识别问题,首先采用内积运算作为两组布尔信号相似性的度量给出了基于标准信号的测量矩阵,并提出了一种对样本权重平衡的方法训练神经网络,实现了对驱动脉冲频率和占空比异常的检测;然后,给出了抗干扰的驱动脉冲边界的识别方法;最后,通过实验对该方法进行了验证。实验结果表明:该方法可对驱动脉冲的信号质量和边界进行有效识别。     

READY,SET, TRACE

Tracing small arms and light weapons has been identified as an important component in reducing the illicit trafficking of weapons to regions of conflict as well as use in violent crime. At the national, regional and international levels policy makers and practitioners are working to make tracing more effective. This article outlines some of the key elements of an effective tracing regime and reviews where areas of agreement currently exist. It concludes with observations on some of the challenges facing countries as they try to implement these systems and respond to the problem of illicit arms trafficking.     

基于扩张观测器的三维有限时间收敛导引律

为了保证视线角速率在弹目碰撞前收敛到零附近的较小邻域内从而达到准平行接近的状态,本文基于自抗扰控制的不确定性估计补偿思想,应用反演控制方法设计了一种考虑导弹自动驾驶仪二阶动态特性和目标机动的三维有限时间收敛导引律。根据有限时间收敛控制理论,严格证明了系统的有限时间收敛特性;为抑制量测噪声,将传统跟踪微分器进行改进并应用于扩张状态观测器与反演控制的设计中。仿真结果表明:在自动驾驶仪响应延迟情况下,所设计的导引律能够导引导弹在有限时间内精确地拦截高速机动目标;改进的跟踪微分器精度高、响应快;基于改进跟踪微分器的扩张观测器估计效果理想。     

Consumer drone evolutions: trends,spaces, temporalities,threats

ABSTRACT

While the drone has become synonymous with the War on Terror, the asymmetric iconography of the battlefield is shifting. Commercially available off-the-shelf (COTS) drones are increasingly prevalent features of global battlefields, employed by non-state actors in both visualising such spaces, and the directing and inflicting of harm. As such usage increases, so too do concerns around their evolving adoption, adaptation, and potential portability into homeland spheres. While cognizant of the range of positive drone applications, it is asserted that drones nonetheless remain simultaneously bound to an inverse potential for exploitation. In examining drone risk, this article approaches the consumer drone through a series of sites and spaces through which it is technically and socially constructed. Reflecting upon industry innovation, community-driven experimentation, and evolving airspace – it calls for greater attention to the drone’s malleability, arguing that understandings of COTS drones must remain attentive to both drone potential and potential drone threat.     

COOPERATION,SIGNALS, AND SANCTIONS

This paper uses game theory and modeling to address the role of incentive structures and information dynamics in nuclear inspections. The traditional argument is that compliant states should be willing to allow inspections to prove their innocence, while proliferating states are likely to impede inspections. This argument does not take into account the historical variation in inspection, signaling, and sanctioning behaviors. Using a game theoretic analysis and model, it is shown that the separation of proliferators from nonproliferators only occurs when the likelihood of proliferation is high and punishment costs are moderate. The model assumes that states can choose how much to cooperate with inspectors and must pay opportunity or secrecy costs when inspections are effective. The results are tested against a set of real-life cases, providing support for the claims of historical variation and the model's deductive propositions.     

Drones,spies, terrorists,and second-class citizenship in Pakistan

This essay reviews seven recent books and reports that focus upon the use of US armed drones in Pakistan's Federally Administered Tribal Areas (FATA). This essay synthesizes a historical account of the program, critically interrogates key arguments and evidence advanced by the authors, and draws attention the particular problems that confront those who live in the FATA and the second-class citizenship that the Pakistani state has bestowed upon them for reasons of domestic and foreign policy concerns. This review essay does not intend to be the final word on any of the ongoing policy debates. But it does hope to enable a wider audience to take part in these important deliberations.     

Terrorism,insurgency, kidnapping,and security in Africa's energy sector

Energy continues to serve as the bedrock of modern economies and the main driver of modern society. For Africa, the production and supply of energy resources such as crude oil, natural gas, uranium, coal, biomass, biofuels and other renewables are an important source of employment, rents, taxes, royalties and profits. This sector brings in several tens of billions of dollars of revenue annually. The production and delivery of such resources, however, depend on critical infrastructures such as pipelines, refineries, processing plants, terminals, rigs, electrical energy pylons, substations, pump stations, vessels, and tankers. These infrastructures have been attacked by terrorists, insurgents, vandals and saboteurs, all of whom see them as targets against which to register their grievances and extract concessions from the state. This paper is a chronological account of some of the documented incidents of terrorism, insurgency, kidnapping, destruction, sabotage, and human casualties suffered in the oil and gas sectors in Africa between 1999 and 2012. It is based on data extracted from the databases of the RAND Database of World Terrorism Incidents and the University of Maryland's Global Terrorism Database (GTD).     

Ethnicity,class, and civil war: the role of hierarchy,segmentation, and cross-cutting cleavages

Why are some countries prone to ethno-nationalist conflict, whereas others are plagued by class conflict? This is a question that has seldom been raised and rarely been examined empirically. This paper presents a social-structural theory to account for the variable incidence of these two forms of political instability. These two types of conflict result from distinct principles of group solidarity – ethnicity and class – and since each individual is simultaneously a member of an ethnic group (or many such groups) and a particular class, these two principles vary in the degree to which they are mutually exclusive or cross-cutting. The degree of economic stratification between groups and economic segmentation within them shapes the relative salience of each principle of group solidarity in any society and is associated with a characteristic form of political mobilization. In places where between-group inequalities are high, and within-group inequalities low, ethnicity should be the dominant principle of group solidarity and serve as the primary basis of group conflict. By contrast, in countries where between-group inequalities are low, and within-group inequalities high, class is more likely to serve as the dominant principle of group solidarity, and conflicts along class lines are more likely. We test these conjectures with data in over 100 countries on cross-cutting cleavages, ethnic war, and class conflict. The results are supportive of the theory, and provide evidence that how groups are stratified and segmented in societies shapes the type of civil war.