共查询到20条相似文献,搜索用时 78 毫秒
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基于最大似然的准则,研究了理想信道估计条件下和非理想信道估条件下OFDM系统的最优检测算法。研究结果表明,当发送信号为PSK调制方式时,无论是理想信道估计还是非理想信道估计,最大似然检测算法与传统的迫零检测算法等价。但当信道估计非理想且发送信号的调制方式为16QAM或高阶QAM时,采用最大似然检测算法才能够获得更好的性能。 相似文献
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对3种抽样方式讨论了余重对数二元回归概率模型的极大似然估计和极大惩罚似然估计。并对数据及模型作了进一步的推广。 相似文献
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如何利用较少的阵元个数得到比较理想的空间分辨力,准确找到噪声源位置,一直是人们比较关心的问题,因此介绍了基于最大似然估计的辐射噪声源近场定位方法,并利用遗传算法寻求最大似然估计的全局最优解,从而实现噪声源近场定位,其具有比常规聚焦波束形成更高的空间分辨力,且可以有效实现相干声源近场定位。通过计算机仿真详细分析了信噪比、测量距离及基阵孔径对本文算法定位性能的影响,说明了仅利用小孔径基阵就可实现辐射噪声源近场高分辨定位,最后通过湖试实验验证了该方法的有效性,具有一定的工程应用价值。 相似文献
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本文提出了在最大似然阵处理中以矢量的内积运算代替交错投影法的二次项运算的迭代算法。这种算法减小了运算量,收敛、性能好。计算机模拟结果验证了算法的有效性。 相似文献
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介绍了已有的分布源目标方位估计中的最大似然估计(MLE)算法,它是四维非线性最优化问题,文中称之为四维MLE算法,因计算量庞大,同时提出了一种降为三维的MLE算法,简化为三维非线性最优化,称之为三维MLE算法。两种算法均采用牛顿型搜索算法,来搜索未知参数的全局最优点。在单次迭代过程中,三维MLE算法比四维MLE算法减少了51次协方差矩阵求逆和87次矩阵乘法,搜索效率得到提高,并且节省了存储空间。得出了新算法克拉美-罗界的计算公式,其计算量也有所降低。计算机仿真验证,三维MLE算法和四维MLE算法的估计精度相当,新算法在减少计算量的同时并无损失性能,所以实用性和实时性都得到显著提高。 相似文献
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A hybrid differential evolution and estimation of distribution algorithm based on neighbourhood search for job shop scheduling problems 总被引:1,自引:0,他引:1
Job shop scheduling problem (JSSP) is a typical NP-hard problem. In order to improve the solving efficiency for JSSP, a hybrid differential evolution and estimation of distribution algorithm based on neighbourhood search is proposed in this paper, which combines the merits of Estimation of distribution algorithm and Differential evolution (DE). Meanwhile, to strengthen the searching ability of the proposed algorithm, a chaotic strategy is introduced to update the parameters of DE. Two mutation operators are adopted. A neighbourhood search (NS) algorithm based on blocks on critical path is used to further improve the solution quality. Finally, the parametric sensitivity of the proposed algorithm has been analysed based on the Taguchi method of design of experiment. The proposed algorithm was tested through a set of typical benchmark problems of JSSP. The results demonstrated the effectiveness of the proposed algorithm for solving JSSP. 相似文献
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水平阵是水声通信中常见的阵列接收形式,但垂直阵也有重要的应用场合。文章提出了一种适用于垂直阵的水声通信多通道最大似然联合均衡译码方法,相比现有仅在信道均衡中叠加各通道信号的多通道判决反馈均衡方法(Multichannel Decision Feedback Equalizer, M-DFE),该方法利用最大似然准则,在一体化联合均衡译码过程中融合空间多通道接收信息,将空间增益直接用于抵抗水声信道多途衰落和译码纠错,有效提升了水声通信的性能。仿真结果表明,在误码率同样达到10-3的条件下,该方法所需信噪比相比M-DFE方法可下降2 dB。海上实验结果显示,在多种信道条件下,该方法实现正确译码的通信速率是M-DFE方法的1.25倍以上。 相似文献
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摩擦力是电机运行时受到的外部扰动,会降低直线电机的跟踪精度.根据摩擦模型设计前馈补偿器是降低摩擦影响的重要方法.首先分析摩擦特性,选用合适的摩擦模型.其次设计电机速度前馈控制器和加速度前馈控制器,提高电机的跟踪性能.根据测得的电机在不同速度下的摩擦力值,运用差分进化算法辨识直线电机的摩擦模型参数,以此设计前馈控制器,实现永磁同步直线电机的摩擦抑制.仿真结果表明,摩擦模型能准确描述被测直线电机的摩擦特性,基于摩擦模型辨识结果设计出的摩擦前馈控制器可以有效地消除摩擦力引起的速度粘滑现象并且减小电机的位置跟踪误差. 相似文献
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为了使声呐阵列在有限的载体空间内获得较高的角度分辨率,设计了基于频率分集的多输入多输出(MultipleInput Multiple-Output,MIMO)声呐。该MIMO声呐采用N发M收的布阵方式,接收阵为M元均匀线阵,发射阵由N个阵元组成,且各发射阵元发射中心频率不同、包络相同的窄带信号。建立密集式频分MIMO声呐的回波模型,并以此模型为基础提出了波达方向估计算法方向-相位域多重信号分类(Direction and Phase Domain-Multiple Signal Classification,DPD-MUSIC)算法。仿真实验中以双频MIMO声呐为例,将频分MIMO声呐的DPD-MUSIC算法的估计性能与单输入多输出(Single-Input Multiple-Output,SIMO)声呐MUSIC算法的估计性能进行了对比。仿真结果表明,频分MIMO声呐利用DPD-MUSIC算法可以获得优于等接收阵元数SIMO声呐的角度分辨率和角度估计精度。 相似文献
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A. Nourmohammadi 《国际生产研究杂志》2013,51(10):2833-2855
In this paper, we propose a multi-objective differential evolution algorithm (MODEA) to solve the multi-objective simple assembly line balancing problem type-2 (SALBP-2). This problem arises when in an existing assembly line, changes in the production process or demand structure take place and the organisation wants to produce the optimum number of items using a fixed number of workstations, which is associated with optimally assigning the tasks to an ordered sequence of stations such that the precedence relations are not violated and some measures of performance are optimised. The two considered objectives are: minimising the cycle time and the smoothness index of the assembly line. To that purpose, we develop a MODEA which unlike the existing algorithms deals with the considered objectives separately in selecting the next population members by proposing a new acceptance scheme based on the Pareto dominance concept and a new evaluation scheme based on TOPSIS. Also, by using the Taguchi method, we tune the effective factors of the developed algorithm. Then its efficiency is tested over available assembly line balancing benchmarks and compared to a new algorithm provided recently in the bi-objective SALBP-2 literature. Computational experiments indicate that the developed algorithm outperforms the existing meta-heuristic over a large group of benchmarks. 相似文献
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研究了广播信道分布式干扰消除算法的性能,提出了一种基于动态功率分配的多天线广播干扰信道对齐算法.该算法利用多用户多天线干扰信道相关矩阵的迹来计算分配功率,并采用最大化码流信干噪比的方法来得到预编码矩阵和接收滤波器矩阵.数值仿真表明,该动态功率分配算法与等功率分配算法相比,尽管低负荷下干扰对齐后的平均信干噪比增益不明显,但中、高负荷下其干扰对齐后的平均信干噪比大幅提高,特别是高负荷下可以解决等功率方法存在的信干噪比瓶颈效应.由于低负荷的应用需求并不强烈,因而该算法是一种实用的广播信道干扰消除方法. 相似文献
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Fu‐Kwun Wang Berihun Bizuneh Xiao‐Bin Cheng 《Quality and Reliability Engineering International》2019,35(6):1634-1645
The statistical learning classification techniques have been successfully applied to statistical process control problems. In this paper, we proposed a one‐sided control chart based on support vector machines (SVMs) and differential evolution (DE) algorithm to monitor a process with multivariate quality characteristics. The SVM classifier provides a continuous distance from the boundary, and the DE algorithm is used to obtain the optimal parameters of the SVM model by minimizing mean absolute error (MAE). The average run length of the proposed chart is computed using the Monte Carlo simulation approach. Several simulated cases are conducted using a multivariate normal distribution with 10 and 20 dimensions and three different process shift scenarios. In addition, we consider two non‐normal distribution cases. The ARL performance of the proposed chart is better than the distance‐based SVM chart. A real example is used to illustrate the application of the proposed control chart. 相似文献