Matched interface and boundary (MIB) for the implementation of boundary conditions in high‐order central finite differences

High‐order central finite difference schemes encounter great difficulties in implementing complex boundary conditions. This paper introduces the matched interface and boundary (MIB) method as a novel boundary scheme to treat various general boundary conditions in arbitrarily high‐order central finite difference schemes. To attain arbitrarily high order, the MIB method accurately extends the solution beyond the boundary by repeatedly enforcing only the original set of boundary conditions. The proposed approach is extensively validated via boundary value problems, initial‐boundary value problems, eigenvalue problems, and high‐order differential equations. Successful implementations are given to not only Dirichlet, Neumann, and Robin boundary conditions, but also more general ones, such as multiple boundary conditions in high‐order differential equations and time‐dependent boundary conditions in evolution equations. Detailed stability analysis of the MIB method is carried out. The MIB method is shown to be able to deliver high‐order accuracy, while maintaining the same or similar stability conditions of the standard high‐order central difference approximations. The application of the proposed MIB method to the boundary treatment of other non‐standard high‐order methods is also considered. Copyright © 2008 John Wiley & Sons, Ltd.     

基于内部回归神经网络的强化学习

在强化学习和动态规划算法的基础上,提出一种不需要预测模型的改进的强化学习算法：该学习算法在模型未知和没有先验经验的条件下,能通过自身神经网络的在线学习,有效控制不稳定的非线性系统：该学习算法的网络结构采用内部回归神经网络,这样可以增强网络本身处理动态信息的能力,使其更适合复杂系统的稳定控制。应用到一级倒立摆物理实体的控制．实验结果表明了该学习算法在性能上优于其他同类强化学习算法．     

线性调频信号特征分析及其在现代雷达中的应用

简要介绍现代雷达的发展过程,给出线性词频信号的时域和频域特点,重点计算和分析了此类信号经匹配滤波压缩处理的过程和结果,最后介绍了线性调频信号产生方法和压缩处理方法,以及几种典型应用。     

倾斜并联内螺纹管汽-水两相流密度波型脉动试验研究

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Microwave joining of two long hollow tubes: an asymptotic theory and numerical simulations

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基于空间谱的多天线盲频谱感知算法

现有的频谱感知算法主要在时间、频率以及地理空间维度进行检测,对角度维的利用尚不成熟。将多天线技术中的到达角（AOA, angle of arrival）估计算法应用到频谱感知领域,提出了2种基于空间谱的盲频谱感知算法,分别为最大—最小延迟相加谱值比检测和平均—最小延迟相加谱值比检测。利用空域匹配滤波的优势,新算法在低信噪比下得到了较高的检测概率,同时为角度维的频谱接入提供了AOA信息,从而提高了频谱利用率。此外,运用随机矩阵理论,推导了检测阈值和检测概率的理论值。仿真结果表明,在Nakagami-m信道下,提出的算法具有比现有盲感知算法更优的检测性能。     

灰阶纯位相匹配滤波器编码方法研究

根据空间光调制器的相位调制作用,提出了一种灰阶纯位相匹配滤波器编码方法。计算机仿真和光学实验结果均表明该方法在相关峰值、信噪比和峰相关能量比等方面比二元纯位相编码方法均有较大提高。另外还给出了相关峰的位置变化规律,有利于对目标的定位。     

嵌入匹配网络的电小天线的优化设计

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基于主成分分析的MACH滤波器设计

针对解决畸变不变目标识别中选择目标样本数目过多的问题,提出了一种基于主成分分析的MACH匹配滤波器设计方法,这是使用去除冗余的本质特征图像来替代目标样本图像的一种方法,能够减少匹配滤波器设计的样本数量,在对一定范围内的畸变目标进行识别,只需要少数几个匹配滤波器就可以完成,而且同一匹配滤波器还可以对不同的畸变方式(如尺度缩放、角度旋转、运动模糊失真)目标进行识别,实验结果表明,这种匹配滤波器在较大的畸变范围内仍然能够得到较尖锐的相关峰。     

基于张量滤波器的多波段红外目标辨识

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