四元数矩阵奇异值分解的算法

本文主要讨论了四元数矩阵的奇异值分解,借助于四元数矩阵的复表示矩阵,对其进行双对角化,对得到的双对角矩阵进行奇异值分解,并构造左右奇异值向量,给出了四元数矩阵奇异值分解的一个算法。     

基于四元数矩阵奇异值分解的彩色图像匹配方法

提出了一种基于四元数的彩色图像匹配算法.该算法将彩色图像用四元数矩阵模型描述,抽取四元数矩阵的奇异值作为匹配特征.对奇异值进行去噪处理,增+了匹配算法的抗噪能力.采用分层搜索策略,减少运算量,提高了匹配速度.实验结果验证了方法的有效性.     

四元数分形奇异值分解方法与彩色图像重建

基于四元数矩阵彩色图像奇异值分解,得到表征彩色图像的不同分量的奇异值,运用分形快速确定图像的拐点。该方法具有快速和简单可行的优点。以受噪声污染图像为例,该方法针对彩色图像去噪具有较好的效果。     

麦克风阵列声源定位的实验设计与实现

基于麦克风阵列的声源定位技术,可以应用在智能交互、智能家电、视频会议、语音识别等领域。该文设计了一个使用麦克风阵列进行声源定位的综合型实验项目,并应用到本科生开放创新实验中。实验充分利用多个麦克风阵元间的空域和时域信息,采用时延估计算法对不同阵元波达时间延迟进行估计。通过构建阵元几何关系并利用阵元信号的时延,获得了在噪声环境下较好的声源定位效果。教学实践表明,该实验项目可以较好地拓展学生的信号处理能力,有利于对学生创新设计能力和解决复杂问题能力的培养。     

基于近场声聚焦的水下目标方位估计

基于水下无人平台的目标定位与跟踪技术逐渐成为近年来水声工程中的研究热点。随着目标辐射噪声级越来越低、探测平台需要尽量靠近被探测目标以实现近场定位。针对利用线列阵聚焦波束形成进行定位处理时出现"左右舷模糊",且目标定位精度低的问题。本文研究一种基于最小方差无畸变响应(MVDR)的半圆阵近场声聚焦技术,以近场声传播特性为基础推导近场半圆阵信号处理的数学模型,理论推导结果证明半圆阵能够克服直线阵存在的方位模糊缺点。最小方差无畸变方法根据信号子空间与噪声子空间的能量特性差异实现对目标的方位估计。数值仿真结果说明,半圆阵近场声聚焦技术的定位性能明显优于线列阵,可以获得目标的高方位分辨率。     

平面相控阵天线的单元设计与分析

基于工作频率在1.79GHz的矩形微带天线,利用FDTD进行建模和仿真,设计出几种平面阵列天线。针对三角阵和矩形阵,分别计算了它们的远场辐射方向图,讨论了阵列天线单元分布的影响,对比分析了微带阵列天线的主要性能参数,计算了前后比和波瓣宽度,并得出了结论。仿真实验结果表明,和三角阵相比,使用4元矩形阵能提供较高的增益和较低的栅瓣电平。     

关于正定矩阵子矩阵的范数不等式

对于两个正定矩阵的子阵的奇异值之间的关系,给出了一个范数不等式。     

一四元数矩阵方程的最小二乘解

利用四元数体上自共轭矩阵的奇异值分解,得到了实四元数矩阵方程X+AXB=C的最小二乘解的表达式,同时给出了在相应解集中矩阵方程的极小范数解.     

基于Matlab的阵列天线方向图仿真北大核心

构建直线阵列、圆阵列和平面阵列天线的数学模型并推导其阵因子表达式,借助Matlab对3种不同类型的阵列天线方向图进行仿真研究。对比阵元数、波长、阵元间距等参数对不同类型阵列天线方向图的影响,仿真结果表明:直线阵、平面阵的性能与阵元数、阵元间距呈正相关,与波长呈负相关;圆阵的性能与阵元数呈正相关,而与圆阵半径和波长的关系并不是线性的。     

基于长基线系统绝对测阵的测距修正算法优化

长基线水声导航定位系统工作前必须首先完成对海底应答器基阵坐标的精确测量和校准,即绝对测阵。由于测量母船有速度,导致发射和接收点分离,使得测距数据与实际距离存在偏差。文章提出新的测距修正算法并通过基于测阵模型的仿真比较,有效降低修正误差,系统的精度有较大提高。     

地面干扰源定位问题中飞机参数估计新方法

民航地空通信受到无线电干扰会严重危机民航飞机的正常飞行。发射信号经过飞机反射后的回波信号中包含了与目标有关的多普勒频率信息,通过对多普勒频率信息检测便可以实现对目标的定位。但是怎样获得飞机的实时状态信息成为另一个研究的重点。本文在地面干扰源定位的研究背景下,提出了一种估计飞机运动状态信息的新方法。首先提出一个新的回波信号模型。并采用二维MUSIC算法实现了目标的二维角的联合估计。进一步,根据阵列模型中的几何关系,实现了对目标的运动状态及空间位置估计,从而实现了对飞机状态信息的准确的实时估计,为后续地面干扰源定位打下良好的基础。仿真实验验证了算法的有效性。     

基于时延抽头模型的宽带信号方位谱估计

讨论了均匀圆阵中宽带信号的谱估计问题.将目标带宽分成若干个不重叠的子频带,并将时延抽头模型方法用于均匀圆阵宽带信号的采集中,然后用MUSIC算法估计信号的来波方向.仿真结果表明该方法的有效性.     

线阵组合平面阵的指向性研究

利用Bridge乘积定理得到了线阵组合平面阵的指向性函数,并运用MATLAB软件绘制出该阵列的三维指向性图.借助于此图分析了线阵组合平面阵的指向性特点,以及声波的波长、阵列的尺寸对指向性的影响.该研究对线阵组合平面阵的设计提供了参考.     

A new approach for target motion analysis with signal time delay

A new approach is proposed in this paper for the problem of the target motion analysis (TMA) with signal propagation time delay. This problem is an unobservable tracking problem in which the acoustic signal transmits with time delay. We present an intelligent range parameterized unscented Kalman filter (IRPUKF) algorithm to estimate the state of the nonlinear unobservable tracking system and propose a recursive model parameter online adjustment method to deal with the time delay in signal propagation. In a simulation of tracking target using a maneuvering acoustic sensor with signal time delay case study, the effectiveness and efficiency of the proposed algorithm is testified to perform better, compared with the range parameterized extended Kalman filter (RPEKF) algorithm.     

The Use of Letter Position Cues in the Visual Processing of Words by Children with an Intellectual Disability and Nondisabled Children

TWO EXPERIMENTS were designed to investigate possible deficiencies in strategies used for decoding words by children with an intellectual disability. The experiments focused specifically on the use of letter position cues as aids to word identification. In Experiment 1,20 children with an intellectual disability (ID) aged 10 to 12 years were matched with two groups of nondisabled children, one for mental age (MA) and one for chronological age (CA), on a visual search task, with response times to array types (word, pseudoword, or nonword) and target position in positive arrays as the dependent variable. The ID group showed response time advantages only when the target letter was in the initial position of an array; however both nondisabled groups responded faster when the target letter was in either the initial or final position, compared to the medial position, and this pattern occurred for words (MA group) and words and pseudowords (CA group) but not for nonwords. Experiment 2 extended the investigation to the oral reading of isolated words. In substitution errors made by children with an intellectual disability, the incorrect word tended to resemble the test word only in the initial letter. In errors made by MA‐matched children, however, both the initial and final letters tended to be the same as those in the test word, suggesting that these are salient cues to word recognition. The findings are interpreted with reference to previous work on early reading acquisition and to research which suggests a more generalised deficiency in the acquisition and use of strategies by ID subjects in cognitive tasks.     

Pithc-synchronous articulatory synthesis incorporated with the inverse solution of speech production

This paper presents a new proposal to synthesize natural sounds with less control parameters by combining the inverse speech production and pitch-synchronous articulatory synthesis. The pitch-synchronous excited Reflection-Type Line Analog (RTLA) model is employed as the synthesis filter. Multi-rate system sampling and dynamic scattering wave adjustment are used to handle the variable VT length and the acoustic continuity. The synthesizer is controlled by vocal-tract (VT) area functions. Given the targets of formant trajectories, the dynamic VT area function which is modeled by time variant VT length is derived using an inverse solution of speech production. A distinguishing feature of this method is that artificially specified formant trace can be precisely aimed in the synthetical sounds. Experimental results show that the formant target can be well matched by the synthetic sounds. Potential application to text-to-speech conversion of this method is discussed. Project supported by NSFC (69972046), and Zhenjiang Provincial Natural Science Foundation of China (698076).     

Source localization with minimum variance distortionless response for spherical microphone arrays

To improve localization accuracy, the spherical microphone arrays are used to capture high-order wavefield information. For the far field sound sources, the array signal model is constructed based on plane wave decomposition. The spatial spectrum function is calculated by minimum variance distortionless response (MVDR) to scan the three-dimensional space. The peak values of the spectrum function correspond to the directions of multiple sound sources. A diagonal loading method is adopted to solve the ill-conditioned cross spectrum matrix of the received signals. The loading level depends on the alleviation of the ill-condition of the matrix and the accuracy of the inverse calculation. Compared with plane wave decomposition method, our proposed localization algorithm can acquire high spatial resolution and better estimation for multiple sound source directions, especially in low signal to noise ratio (SNR).     

岩石声波测试实验数据高速传输及多点测试方法探讨

针对实验室现有非金属声波检测仪在使用中存在的问题,研究了实现岩石声波数据高速传输的方法,探讨了实现对岩石试样进行多点声波测试所需装置的设计思路,结果表明,该方法与装置可实现对围岩或岩石声波测试实验数据的高速传输,并可对围岩或岩石多点位的声波进行监测。     

混合气体各组份浓度的C程序设计

气体组份的分析在许多领域特别是在环境保护中具有重要意义，对于混合气体中各组份浓度的分析，人们提出了多种方法．章根据气体的光声效应，利用气体的光声光谱对混合气体各组份的浓度用C语言编程进行计算。     

声目标识别技术研究

本文对声目标识别的关键技术进行研究,探讨用小波分析来进行声信号处理和特征提取,用BP神经网络和支持向量机的模式分类方法来进行分类识别.通过对四种声信号的仿真实验表明,使用小波变换和人工神经网络技术及支持向量机分类技术相结合对声目标进行识别是有效、可行的.