新的互补序列在雷达通信一体化中的应用

雷达通信一体化能有效整合系统射频资源,可利用射频前端同时实现目标探测和通信.针对一体化中存在的随机通信数据引起的高距离旁瓣及严重的回波遮掩性问题,提出了一种基于离散傅里叶矩阵循环扩展的互补码构造方法,设计了一种新的基于完全互补码的雷达通信一体化方案,该方案采用扩频多载波信号形式.理论分析和仿真结果表明,所提出的信号设计...     

基于特征值的频谱感知算法仿真研究

频谱感知是认知无线网络中的一个重要功能,是实现其他功能的基础。研究了新型的基于特征值的感知算法,充分利用随机矩阵的渐近谱分布特性和特征值的收敛特性来设置判决门限,提高感知性能。理论分析和仿真结果均表明,新型算法性能明显优于典型的能量检测算法,克服了能量检测算法的噪声不确定性问题。

Abstract：

Spectrum Sensing is an important function in the cognitive radio networks.A new eigenvalue-based detection scheme for spectrum sensing was studied,and decision thresholds were set to have good performance by using the property of asymptotic spectrum distribution and convergence of maximum eigenvalue of random matrices.Theoretical analysis and simulations results show that the new detection scheme can obviously outperform the classical energy detection,and overcome the noise uncertainty problem.     

确定测试性验证试验方案的贝叶斯方法

现有的测试性验证试验方案在一定的风险约束下都需要较大的故障样本量。针对这一问题,以故障检测率(fault detection rate, FDR)为验证指标,提出利用研制阶段试验数据和专家信息制定测试性验证试验方案的贝叶斯方法。该方法首先利用研制阶段试验数据建立了产品的FDR增长模型,以此描述FDR在研制阶段的变化趋势,然后利用专家信息确定模型中的超参数,进而得到FDR的验前分布,最后依据贝叶斯最大后验风险准则制定了新的测试性验证试验方案。通过实例的对比分析表明,与经典试验方案相比,新方案样本量减少效果明显,在样本量保持不变的条件下双方风险大大降低。     

具有概念漂移的P2P网络流量识别研究

针对P2P网络流量产生过程中存在概念漂移现象,提出具有概念漂移检测功能的多分类器动态集成流量识别方案。该方案包括概念漂移检测和分类器动态集成两大模块,由卡方统计推断原理实现概念漂移检测模块功能,采用基分类器的性能优先淘汰策略进行动态集成解决流量概念漂移发生后的识别问题。在以贝叶斯分类器、支持向量机、决策树作为基分类器,针对不同集成规模、数据块大小进行仿真实验,结果证明方案是可行的,模型的识别准确率达到82%以上。     

小子样变总体下的Bayes测试性验证方法

现有测试性验证试验方案一般都需要较大的故障样本量,利用装备研制阶段的测试性数据则可能有效解决这一问题。但研制阶段的测试性数据和现场试验数据一样属于“小子样”且具有“变总体”特点,为此提出一种基于Bayes理论的测试性验证方法。首先根据装备研制各阶段积累的测试性试验信息构建装备测试性参数故障检测/隔离率(fault detection rate/fault isolation rate,FDR/FIR)的动态增长模型,用以揭示装备测试性水平的动态变化规律,并对其测试性指标进行预测。然后根据最大熵原理计算系统FDR/FIR的先验分布。最后结合少量现场试验数据,根据Bayes最大验后风险准则制定装备测试性验 证方案,对装备测试性指标进行验证。通过实例对比分析表明,该方法有效融合了研制阶段数据与现场试验数据,能在小样本的情况下提高验证结论的置信度,降低评估风险。     

Self-organizing map of complex networks for community detection

Detecting communities from complex networks is an important issue and has attracted attention of researchers in many fields. It is relevant to social tasks, biological inquiries, and technological problems since various networks exist in these systems. This paper proposes a new self-organizing map (SOM) based approach to community detection. By adopting a new operation and a new weight-updating scheme, a complex network can be organized into dense subgraphs according to the topological connection of each node by the SOM algorithm. Extensive numerical experiments show that the performance of the SOM algorithm is good. It can identify communities more accurately than existing methods. This method can be used to detect communities not only in undirected networks, but also in directed networks and bipartite networks.     

Detection of Stealthy False Data Injection Attacks Against Cyber-Physical Systems: A Stochastic Coding Scheme

This paper, from the view of a defender, addresses the security problem of cyber-physical systems (CPSs) subject to stealthy false data injection (FDI) attacks that cannot be detected by a residual-based anomaly detector without other defensive measures. To detect such a class of FDI attacks, a stochastic coding scheme, which codes the sensor measurement with a Gaussian stochastic signal at the sensor side, is proposed to assist an anomaly detector to expose the FDI attack. In order to ensure the system performance in the normal operational context, a decoder is adopted to decode the coded sensor measurement when received at the controller side. With this detection scheme, the residual under the attack can be significantly different from that in the normal situation, and thus trigger an alarm. The design condition of the coding signal covariance is derived to meet the constraints of false alarm rate and attack detection rate. To minimize the trace of the coding signal covariance, the design problem of the coding signal is converted into a constraint non-convex optimization problem, and an estimation-optimization iteration algorithm is presented to obtain a numerical solution of the coding signal covariance. A numerical example is given to verify the effectiveness of the proposed scheme.

     

GP-RBF网络应用于飞行器外测数据野值实时剔除

测量数据集合中严重偏离大部分数据所呈现趋势的小部分数据点被称为野值点。野值的实时剔除对提高目标实时跟踪精度有十分重要的意义。采用了一种新的含有广义参数的径向基函数神经网络(GP-RBF网络)对航天靶场外测数据进行野值实时剔除。该网络可以通过对参数的自适应调整达到实时剔除野值的目的。采用经差商预处理后的飞行器弹道仿真数据，构成GP_RBF网络的训练集和测试集，试验结果表明利用该网络可以快速、有效地解决野值实时剔除问题。     

投影寻踪模型在水资源工程方案优选中的应用

提出了水资源工程方案优选的投影寻踪(PP)模型的新方法。利用PP模型可把方案多维评价指标值综合成一维投影值,投影值越大表示该方案优选,根据投影值的大小就可对方案集进行优选。采用实码加速遗传算法进行PP建模,简化了投影寻踪技术的实现过程,克服了目前投影寻踪技术计算复杂、编程实现困难的缺点,为投影寻踪技术在水资源系统工程中的广泛应用提供了新的有力工具。应用实例的结果说明,直接由样本数据驱动的PP模型用于水资源工程方案优选简便可行,PP模型的投影值比较分散、易于决策,适用性和可操作性强,不需确定评价指标的权重,优选结果较为客观。     

在滑动窗口中判决的自适应门限检测方法

对在突发通信中基于噪声功率和基于信号功率的自适应门限信号检测方法进行研究,提出了在滑动窗口中进行比较判决的自适应门限检测方法,用多个采样点进行比较判决以取得最优的同步信号。仿真比较不同情况下的系统性能,结果表明改进方案能得到精确的系统同步信号,低信噪比时,基于噪声功率的自适应检测方法检测概率较大。     

基于STFT的宽带数字ESM接收技术

提出了一种新的基于瞬时测频的宽带数字电子支援（electronic support measure, ESM）接收技术。首先对输入信号进行短时傅里叶变换,通过对变换结果进行快速插值,实现瞬时测频;然后利用多门限完成瞬时频域检测,并根据检测带宽进行抽取。这种新的接收技术能够有效解决ESM系统对宽带同时到达信号的侦收难题,且算法结构规整,易于用现场可编程逻辑门阵列（field programmable gate array, FPGA）芯片进行硬件实现。计算机仿真结果表明,系统单信号检测灵敏度可达-5 dB,当输入信噪比为-5 dB~15 dB时,单信号正确检测概率可达90％以上,动态范围达20 dB,双信号瞬时动态范围可达18 dB。     

基于行空间映射的连续中继网络预编码干扰消除方案

针对转发放大(amplify-and-forward,AF)模式下双路径连续中继(two-path successive relay,TPSR)存在的中继间干扰(inter-relay interference,IRI)问题,提出了新颖的基于行空间映射的中继干扰消除方案。新方案对源节点信号进行交替行空间预编码,从而将接收期望信号与IRI信号映射到不依赖信道的正交子空间,在未知信道下实现IRI和累计噪声的完美消除,从而消除非理想信道估计带来的剩余自干扰和累积噪声对TPSR性能的影响。在这基础上,推导不同信道估计误差下系统平均误比特率（bit error ratio,BER）的闭合表达式和近似表达式,并通过仿真验证理论推导的正确性。通过对比该方案与传统基于信道估计的干扰消除方案在不同估计误差下的检测性能,表明新方案能够完全消除IRI和累积噪声,有效提升连续中继网络性能。     

Compressive sensing based multiuser detector for massive MBM MIMO uplink

Media based modulation(MBM)is expected to be a prominent modulation scheme,which has access to the high data rate by using radio frequency(RF)mirrors and fewer transmit antennas.Associated with multiuser multiple input multiple output(MIMO),the MBM scheme achieves better performance than other conventional multiuser MIMO schemes.In this paper,the massive MIMO uplink is considered and a conjunctive MBM transmission scheme for each user is employed.This conjunctive MBM transmission scheme gathers aggregate MBM signals in multiple continuous time slots,which exploits the structured sparsity of these aggregate MBM signals.Under this kind of scenario,a multiuser detector with low complexity based on the compressive sensing(CS)theory to gain better detection performance is proposed.This detector is developed from the greedy sparse recovery technique compressive sampling matching pursuit(CoSaMP)and exploits not only the inherently distributed sparsity of MBM signals but also the structured sparsity of multiple aggregate MBM signals.By exploiting these sparsity,the proposed CoSaMP based multiuser detector achieves reliable detection with low complexity.Simulation results demonstrate that the proposed CoSaMP based multiuser detector achieves better detection performance compared with the conventional methods.     

航班运行风险网络的传播与控制改进

为探究航班运行风险的产生、传播与控制过程, 首先统计华北区域航班运行数据共计76个风险节点。然后，采用偏秩相关系数构建风险网络, 再使用社团模块探测算法与三角最大滤波法验证网络适用性。并且, 提出一种适用于航班运行风险分析的SEIR(susceptible-infected-exposed-recovered)模型。根据动力学传播结果, 聚类定位网络传播中关键节点。最后, 采用前置预防与战术处置两类控制方案。计算结果表明，仅控制5个节点后, 感染峰值可降低18.44%, 峰值时间推后两个周期, 起降等重要操纵节点被感染次数平均下降11.74%。该方案在感染峰值、感染周期、重要节点感染3个方面的抑制效果均占优。以上结果证实, 所提方案可有效用于航班运行风险问题分析。     

高斯杂波中距离扩展目标的模糊CFAR检测

为提高高分辨雷达的检测性能,提出了一种高斯杂波背景下距离扩展目标的模糊检测方法。该方法采用模糊恒虚警率(constant false alarm rate, CFAR)检测器代替传统的二进制CFAR检测器,将距离单元值转换成映射到虚警空间的模糊隶属函数值,然后采用模糊积累准则进行积累,得到检测统计量。研究了模糊代数积、模糊代数和两种积累准则,推导出这两种方法虚警概率的数学解析式。仿真结果表明,高斯杂波背景下模糊代数积积累较双门限二进制积累可获得近2 dB的性能改善。同时,模糊检测方法只采用单个检测门限,具有易于调节的优点。     

Secret sharing scheme with inherited characteristic

1. INTRODUCTION Secret sharing is an important method to realize the information safety and data encryption in the crypt- ography field. It is also a fundamental protocol and tool in the multi-party setting. Now it has been applied to many applications such as electronic election, dig- ital cash and so on. The concept of secret sharing was invented independently by Shamir and Blakley in 1979, which original motivation is to cope with the problem on the safety of key management. And the b…     

Cochannel interference cancelation for multiple access systems

Many properties of frequency-hopped spread-spectrum multiple access (FH/SSMA), such as, robustness against frequency selective fading and jamming make it a preferred multiple access communication scheme. But cochannel interference (CCI) can seriously harm the system's performance. On the basis of the analysis of the CCI pattern of frequency hopped multiple access signal, a new multiuser detection algorithm for canceling the CCI in frequency hopped multiple access systems is proposed. In the proposed scheme, the CCI is canceled by first detecting the frequency hopping slot, and then classifying and regenerating the candidates of the interference pattern from the time-frequency matrix. Both the theoretical analysis and computer simulation results show that compared to the conventional detector and Mabuchi's detector, this new multiuser detector has lower complexity, better convergence stability, and is suitable for both additive white Gaussian noise (AWGN) channels and Rayleigh fading channels.     

不确定网络化控制系统鲁棒故障检测

针对一类具有未知输入和模型不确定性的网络化控制系统,基于H_∞滤波器研究了系统的鲁棒故障检测问题.利用输入时滞方法,将含有网络传输时滞和数据丢包的不确定网络化控制系统建模成一类具有双加性状态时滞项的连续系统.采用Lyapunov-Krasovskii泛函方法分析了新系统的H_∞性能,并将所得结果应用于原系统鲁棒故障检测滤波器的设计,得到了滤波器存在的时滞依赖条件.最后,通过仿真验证了该方法的有效性.     

一种基于HRCT影像的肺结节计算机辅助检测方法

肺癌是威胁人类生命的第一杀手,如果肺癌能在早期被发现、诊断和治疗,将大大提高肺癌患者的生存率。提出了一种自动的基于高分辨率CT影像(HRCT)的肺结节计算机辅助检测(CAD)方法,可以分为肺实质分割、感兴趣区域(ROI)识别、肺结节特征提取与分类、三维可视化显示几个步骤,综合采用了自适应阈值分割、数学形态学、偏微分方程与不变矩分析等算法。通过对多组肺癌患者CT影像的测试,该方法可以帮助医生有效的提高对于肺癌疾病的诊断准确率。     

考虑多种真实情况的软件可靠性增长模型

进行软件可靠性评估主要通过构建软件可靠性模型实现。软件可靠性模型通常给出被检出的故障可以立即被排除,并且不会有新的故障被引入的假设,这与实际的检错过程是不相符的。针对以上假设条件,提出了一种新的软件可靠性增长模型。该模型将软件的检错过程和排错过程作为两个独立的非齐次泊松过程分别进行建模,并将软件中存在的故障数看作是一个变化的函数,该函数包括软件中初始故障及引入的故障。在两个数据集上进行相应实验证明,较之其他模型,新建模型的拟合和预测效果更好。