On Annihilators in Fewer Variables： Basic Theory and Applications

Algebraic attacks on stream ciphers exploit annihilators of low degree. From another point of view, we concentrate on annihilators in fewer variables in this paper. This work consists of two parts. Firstly, the concept of singular annihilators is proposed and the basic theory is established. Secondly we present two applications of singular annihilators. We propose a variant of the Filter states guessing attack （FSGA） introduced by Pasalic （2009）. Our attack outperforms the FSGA in many cases. Moreover, we put forward a probabilistic algorithm, which can screen out a large number of Boolean functions with annihilators of low degree at a lower cost for the resistance against algebraic attacks.     

滑翔制导炸弹变增益鲁棒控制器设计与仿真

针对滑翔制导炸弹,提出了一种变增益鲁棒控制器设计方法.通过将作战空域划分为几个小空域,并在其中一边界点对线性化后的系统,采用双回路鲁棒设计方法,设计满足系统性能和动态性能的鲁棒控制器.然后在各个边界点,采用插值方法将控制器内回路设计成与高度和速度相关的连续变增益控制回路,使内回路控制参数随着滑翔制导炸弹的飞行状态变化而变化,从而提高系统的性能.仿真结果表明,设计的控制器具有良好的时域响应性能,可以控制滑翔制导炸弹在大范围飞行过程中稳定,获得了满意的控制效果.     

基于Dempster-Shafer证据理论与抗频谱感知数据篡改攻击的协作式频谱检测算法

针对恶意用户伪造认知用户或者控制已有认知用户、频谱感知数据篡改（SSDF）、使现有协作式频谱检测算法的性能大幅下降问题,提出了一种抗SSDF攻击干扰的协作式频谱检测算法。将SSDF攻击干扰分为Ⅰ类和Ⅱ类,通过Dempster-Shafer (D-S)证据理论设置用户权重和判决门限,区分Ⅰ类恶意用户、Ⅱ类恶意用户和可信用户,只使用可信的频谱检测数据进行信息融合,以判决频谱占用的情况、提高检测性能。理论分析与仿真结果表明,该算法能够有效对抗Ⅰ类和Ⅱ类 SSDF的攻击干扰,其检测性能明显优于现有D-S证据融合频谱检测算法。     

一种双基地雷达探测性能评估的改进方法

一发两收配置下双基地高频地波雷达相对于单基地雷达的优势为提高探测精度和目标截获能力.同时, 双基地高频地波雷达作为一种大型的雷达探测系统, 影响其探测性能的因素众多, 为双基地高频雷达探测性能建立一套有效的评估体系, 对于雷达初期建设与使用过程中的维护与升级, 都具有重要的指导意义.本文结合高频地波雷达和双基地雷达各自特点, 提出了一种基于粒子群算法改进的层次分析法, 克服了传统层次分析法的判断矩阵和一致性检测分离的缺点, 提高了评估方法的可信度与可靠性, 为双基地高频地波雷达探测性能评估提供了一种较为可靠的方法.     

频变交叉耦合带通滤波器的耦合矩阵综合研究

综合代表滤波器拓扑结构和特性的耦合矩阵是交叉耦合滤波器设计的重点。提出了一种基于广义特征值的优化综合方法,通过非线性最小二次求解,将耦合矩阵的广义特征值逼近至广义切比雪夫响应多项式传输函数零极值参考点,优化求解出带有频变交叉耦合带通滤波器的耦合矩阵。通过3个数值实例演示了该方法,并验证其有效性。这是对经典带通滤波器耦合矩阵综合方法的补充,为频变交叉耦合滤波器的设计建立了基础。     

Synthesis and growth of nonlinear infrared crystal material CdSe via seeded oriented temperature gradient solution zoning method

Single crystals of CdSe were grown by using seeded oriented temperature gradient solution zoning (STGSZ) method with the sizes of 20 mm in diameter and 80 mm in length. The crystals were characterized with X-ray diffraction, transmission spectrophotometer and infrared microscope. The transmission spectra showed that the infrared transmission is above 65% and the mean absorption was 0.01-0.04 cm-1 in the range of 2.5-20 μm.With 2.797 μm Cr, Er:YSGG laser as pumping source,experiments of optical parametric oscillator (OPO) were performed by using fabricated 5mm×5mm×30mm device crystal. The signal and idler wavelengths and the output average power were respectively 4.3 μm, 8 μm and 400 μJ. Optical-to-optical conversion efficiency was obtained by 12%.     

常见3G流媒体业务投诉的分析与排查

3G流媒体业务,是移动通信发展的方向.随着3G多媒体手机的大规模上市,以手机为载体的相关产业也将随之得到空前发展,通过音频、视频工具提供的服务将占主导地位.但运营商要发展流媒体业务还需解决诸多技术问题,如文件制作技术、文件定位调度管理技术、节点选择技术、同步技术、容错技术、终端能力以及安全机制等.结合日常流媒体投诉处理的一些经验,总结出几种常见流媒体业务投诉的处理和分析方法.     

蜂窝物联网中短包域能量效率最大化波束成形优化与设计

为了满足未来蜂窝物联网(IoT)中超高可靠和超低时延的要求,该文提出一种适用于多小区多用户超高可靠极低时延网络短包域公平性能量效率最大化算法。首先,以最小用户传输速率、每个发射机最大功率等约束为限制,构建了一个关于波束成形矢量的非线性分式规划资源配置模型。随后,采用变量代换、连续凸近似等技术,将原始非凸优化问题转化为标准的凸问题,进而提出一种短包域迭代能量效率最优化方法进行求解。最后,数值仿真结果验证了所提算法在短包域具有良好的能量效率性能。     

Joint frequency and DOA estimation using spatial-temporal co-prime sampling with off-grid sources

A method of joint frequency and direction of arrival (DOA) estimation using spatial-temporal co-prime sam-pling with off-grid sources was proposed to solve the problem of two-dimensional (2D) mismatches of signals.Firstly,the received signal was sampled by spatio-temporal co-prime sampling technique to construct 2D sparse reconstruction model with the filled coarray.Then the frequency mismatch term and angle mismatch term were incorporated into the re-ceived data model.Based on the above modified model,an improved greedy algorithm was presented to obtain the fre-quency mismatch and angle mismatch by estimating the spectrum leakage terms jointly.So the 2D off-grid sources can be corrected to accurate positions.The method can increase the degrees of freedom (DOF) in the space-frequency domain.Moreover,the method has reduced the amount of computation,and it can improve the frequency and DOA estimation accuracy in the meantime.Simulation results demonstrate the correctness and effectiveness of the proposed approach.     

Efficient distributed traffic offloading algorithm based on SDN architecture

For addressing the problem of mobile data traffic offloading,network service cost minimization problem model was proposed,which considered the cost of base stations and the consumption of access points under the SDN architecture.Due to the defects of convergence speed and privacy security in the traffic offloading algorithm based on dual decomposition,the traffic offloading algorithm based on proximal Jacobian ADMM was proposed and an implementation scheme to ensure the privacy and security was designed.Meanwhile,the simulation results show that the algorithm based on the proximal Jacobian ADMM is superior to the dual decomposition algorithm in terms of convergence speed.