分形海面及其上方目标电磁散射的混合算法

采用一维带限Weierstrass分形粗糙海面模拟实际的粗糙海面,运用基于矩量法(method of moment, MOM)结合基尔霍夫近似(Kirchhoff approximation, KA)的混合算法,研究了分形海面与上方需考虑旋转的复杂矩形截面导体柱的复合电磁散射。将不同入射角情形下的混合算法计算结果与传统的MOM结果进行了比对,结果表明该混合算法具有较高的准确性和计算效率。最后,讨论了复合散射系数与粗糙海面参数、目标参数以及入射波参数之间的依赖关系,得到了较完整的复合电磁散射特征。     

基于模糊综合评判的机场打击效果评估

针对机场打击效果评估这一热点问题,根据机场的基本组成结构和特点,提出了基于几何、纹理和整体特征的机场毁伤评估准则以及知识推理模糊综合评估数学模型,对模型的结构和评估过程进行了一定的描述,研究并实现了基于模糊综合评判理论的机场跑道打击效果评估系统。实验结果表明,该系统是一种可行的机场打击效果评估系统。     

基于数据融合技术的多属性群决策方法

利用模糊数相关理论及数据融合技术,对不同决策者对同一个方案的评价值具有不同程度冲突,属性值和属性权重均为模糊数的多属性群决策问题提出了解决方案。对模糊数的排序问题,利用可信性测度概念,通过模糊模拟方法对两个模糊数比较的大小进行计算,并建立互补判断矩阵得到最终的排序结果。算例的结果证实了该方法的可行性、有效性和合理性。     

Clustering routing algorithm of wireless sensor networks based on Bayesian game

To avoid uneven energy consuming in wireless sensor networks, a clustering routing model is proposed based on a Bayesian game. In the model, Harsanyi transformation is introduced to convert a static game of incomplete information to the static game of complete but imperfect information. In addition, the existence of Bayesian nash equilibrium is proved. A clustering routing algorithm is also designed according to the proposed model, both cluster head distribution and residual energy are considered in the design of the algorithm. Simulation results show that the algorithm can balance network load, save energy and prolong network lifetime effectively.     

基于修正贝努利滤波的被动多目标跟踪算法

针对势平衡多目标多贝努利(cardinality balanced multi target multi Bernoulli, CBMeMBer）滤波中的量测信息弱化问题,提出一种改进的多目标多贝努利（improved multi target multi Bernoulli, IMeMBer）滤波。该算法通过对漏检目标的多贝努利随机集进行修正,在解决目标数过估问题的同时,避免了CBMeMBer滤波中的量测信息弱化问题。在此基础上,将高斯粒子滤波引入IMeMBer算法中,通过一组高斯粒子近似多贝努利随机集中元素的概率分布,实现被动测角情况下的多目标跟踪。仿真结果表明,所提算法能够以较小的运算代价达到高斯混合粒子劳势估计的概率假设密度滤波相似的跟踪精度,具有良好的工程应用前景。     

Lattice-reduction-aided MMSE precoding for correlated MIMO channels and performance analysis

The lattice-reduction (LR) has been developed to improve the performance of the zero-forcing (ZF) precoder in multiple input multiple output (MIMO) systems. Under the assumptions of uncorrelated flat fading channel model and perfect channel state information at the transmitter (CSIT), an LR-aided ZF precoder is able to collect the full transmit diversity. With the complex LenstraLenstra-Lova′sz (LLL) algorithm and limited feedforward structure, an LR-aided linear minimum-mean-square-error (LMMSE) precoder for spatial correlated MIMO channels and imperfect CSIT is proposed to achieve lower bit error rate (BER). Assuming a time division duplexing (TDD) MIMO system, correlated block flat fading channel and LMMSE uplink channel estimator, it is proved that the proposed LR-aided LMMSE precoder can also obtain the full transmit diversity through an analytical approach. Furthermore, the simulation results show that with the quadrature phase shift keying (QPSK) modulation at the transmitter, the uncoded and coded BERs of the LR-aided LMMSE precoder are lower than that of the traditional LMMSE precoder respectively when E b / N0 is greater than 10 dB and 12 dB at all correlation coefficients.     

BNE-based concurrent transmission considering channel quality and its PSO searching strategy in Ad Hoc networks

The paper proposes a decentralized concurrent transmission strategy in shared channels based on an incomplete information game in Ad Hoc networks.Based on the nodal channel quality,the game can work out a channel gain threshold,which decides the candidates for taking part in the concurrent transmission.The utility formula is made for maximizing the overall throughput based on channel quality variation.For an achievable Bayesian Nash equilibrium(BNE) solution,this paper further prices the selfish players in utility functions for attempting to improve the channel gain one-sidedly.Accordingly,this game allows each node to distributedly decide whether to transmit concurrently with others depending on the Nash equilibrium(NE).Besides,to make the proposed game practical,this paper next presents an efficient particle swarm optimization(PSO) model to fasten the otherwise very slow convergence procedure due to the large computational complexity.Numerical results show the proposed approach is feasible to increase concurrent transmission opportunities for active nodes and the convergence can be swiftly obtained with a few of iteration times by the proposed PSO algorithm.     

星载双基地雷达杂波抑制能力分析与构型优选

星载双基地雷达具有覆盖范围广、抗隐身,抗干扰等优势,在未来具有极大的应用潜力.然而,由于星载双基系统具有轨道构型差异大、空间尺度异构的特点,使得双基系统的杂波谱结构在不同的轨道构型下具有较大的差异.本文结合星载双基几何模型,综合考虑分辨率空变、地形起伏等因素对杂波协方差矩阵的影响,分析了同轨道高度下的类单基构型与远距双...     

基于改进的SVM学习算法及其在信用评分中的应用

对于处理大规模问题的信用评分方法除要求达到一定的准确率之外,其速度、可解释性、简洁性等性能也非常重要. 借鉴SMO的思想, 首先提出一个基于三变量的改进的SVM学习算法, 即将SVM问题分解为一系列含有三个变量的二次规划子问题,其优点是所求的相应松弛子问题都有解析解,使得该方法能够更加精确和快速地逼近最优解;其次将新算法应用于信用评分问题,在UCI机器学习库中的三个公共数据集上的数值试验表明了新方法的有效性:不仅节省了模型的计算代价, 而且还提高了分类精度.     

多元LDPC随机译码的似然概率快速生成算法

多元随机译码算法能有效解决译码复杂度高的问题,但似然概率生成的计算仍有较高的计算复杂度. 为解决这一问题,文中提出一种针对M阶正交振幅调制下的多元低密度奇偶校验码的随机译码算法. 通过计算星座图中部分星座点和接收信号点之间的欧几里德距离来确定随机译码的似然概率,而不必计算所有星座点的似然概率,省去了复杂的幂次运算. 仿真结果表明,该算法能有效降低多元LDPC码随机译码的计算复杂度,性能损失较小,是一种适合多元LDPC译码器前端实现的译码算法.