基于Matlab的信号与系统教学改革初探

本文针对学生在学习"信号与系统"这门课程中所存在的问题,引入Matlab软件,使这门课程的计算机辅助更便捷。通过运用Matlab工具实现。"信号与系统"中时域运算的演示,频域抽样定理的具体实例。Matlab使得信号系统中复杂的计算和抽象问题变得直观和简单。Matlab软件的引入大大改善了"信号与系统"课程的教学方法和手段,丰富了教学内容,取得了良好的教学效果,提高教学的效率。     

Matlab在"信号与系统"教学中的应用研究

本文针对学生在学习"信号与系统"课程中存在的问题,提出在该课程教学中引入Matlab软件辅助课程教学的思路.通过运用Matlab实现信号时域运算的演示、频域抽样定理等具体实例,说明引入Matlab软件对改善"信号与系统"课程的教学方法和手段,丰富教学内容,提高课堂教学效率具有良好的促进作用.     

Matlab在"信号与系统"分析中的应用

Matlab的出现使"信号与系统"课程的计算机辅助教学更为便捷.本文详细论述了使用Matlab工具将"信号与系统"中复杂的理论计算和绘图等抽象问题通过编程变得简单而直观.Matlab的运用大大改善了"信号与系统"的教学方法和手段,丰富了教学内容,取得了良好的教学效果,对于教学水平的提高十分有益.     

信号与系统仿真实验的研究

传统的实验手段无法全面的反映“信号与系统”课程中的许多基本理论,特别是非周期信号的时域与频域分析、基本运算性质、系统的设计与实现等。本文展开了计算机仿真和虚拟实验的研究,力求用形象生动的二维、三维图形表现形式,加深学生对“信号与系统”课程理论的理解。     

基于卷积运算的多载波信号分析与仿真

"信号与系统"课程是电类专业的重要主干课程,在学习掌握信号与系统分析基本原理与方法的基础上如何做到学以致用,以提高学生的学习兴趣与实践能力,应该是任课老师必须思考的一个问题.本文基于信号与系统的基本理论与分析方法对OFDM信号传输过程进行了分析与探讨,以使学过信号与系统及通信原理课程的同学也能理解与掌握OFDM信号的传输原理与结构特点.应用Matlab仿真环境建立了OFDM传输方案的仿真平台,通过实验,提高学生的分析能力、理解问题能力及实践动手能力.     

Matlab在“信号与系统”分析中的应用

Matlab作为时下最流行的一种工程类软件,在汽车行业、计算机技术、语音处理、图像信号处理等诸多行业当中都有较为广泛的应用。将其应用在理论性较强、系统分析复杂、现代高校电信等专业必修的"信号与系统"知识分析当中尤为重要。本文在简单介绍Matlab内容和信号与系统内容的基础上,对Matlab在"信号与系统"中信号分解与合成、复杂模型处理和系统S域分析几方面的应用进行了详细的论述。     

小波分析在微型光谱仪信号去噪处理中的应用

针对微型光谱仪光谱信号存在的噪声问题,利用小波变换在时频域具有多分辨率,能同时进行时频域局部分析的特性,运用Mallat分解和重构算法,通过C语言编程实现对光谱信号的噪声抑制.将程序应用到MS-Ⅱ明思微型生化分析仪系统中,对算法的有效性进行了验证.结果表明,用小波变换对光谱信号进行分析和处理,提高了光谱信号分析的精度,从而提高了系统测试的准确性和稳定性.     

基于Rimoldi分解的连续相位调制信号Turbo频域均衡算法

针对高阶部分响应连续相位调制(CPM)信号均衡中存在的复杂度高和性能较差等问题,该文从Rimoldi分解的角度出发,设计了一种新的适用于倾斜相位CPM信号的发射帧结构,并在此基础上结合单载波频域均衡(FDE)和Turbo均衡的思想,提出了一种适用于高阶CPM信号的Turbo频域均衡算法。该算法通过将信号均衡转化到频域进行处理,避免了时域均衡算法在计算均衡器系数时存在的大矩阵求逆问题,同时使用Turbo均衡的软信息迭代处理来改善系统的性能。理论分析和仿真结果表明,对于四阶部分响应CPM信号,在存在严重符号间干扰的多径衰落信道的条件下,该算法与现有的基于符号的频域均衡算法相比,在保持较低复杂度的同时,具有大约1.5 dB的性能增益。     

"信号与系统"课程中的教学互动

本文论述了对"信号与系统"课程中师生互动方式的思考.在分析"信号与系统"课程教学过程中存在问题的基础上,结合教学实践,着重阐述了课堂互动方式、作业本互动方式以及学习论坛互动方式三个方面的内容,其中重点介绍了本课程的学习论坛可支持公式的在线输入,解决了本课程网络互动难以广泛开展的难题.教学实践证明这些教学互动方式对提高教学质量有重要作用.     

“信号与系统”教学中工程实践能力的培养

"信号与系统"课程的理论概念抽象,课堂上直接理解吸收较困难。教师在授课过程中,适当地引入一些工程实践项目与实验环节可以加强学生对基础理论与工程分析思想的理解与掌握,从而更好地提高学生分析问题和解决问题的能力,以实现学以致用,理论联系实际。     

微透镜阵列的制作及其在光场成像中应用的研究进展

文章综述了微透镜阵列制备技术的最新研究进展,并将这些制备方法分为直接法和间接法进行了对比分析。回顾了微透镜在光场成像应用中的研究进展,指出目前该领域的研究重点是光场相机设计的新思路及提高分辨率的相应模型算法。     

基于可变形卷积神经网络的遥感影像密集区域车辆检测方法

车辆检测是遥感图像分析领域的热点研究内容之一,车辆目标的智能提取和识别,对于交通管理、城市建设有重要意义。在遥感领域中,现有基于卷积神经网络的车辆检测方法存在实现过程复杂并且对于车辆密集区域检测效果不理想的缺陷。针对上述问题,该文提出基于端到端的神经网络模型DF-RCNN以提高车辆密集区域的检测精度。首先,在特征提取阶段,DF-RCNN模型将深浅层特征图的分辨率统一并融合;其次,DF-RCNN模型结合可变形卷积和可变形感兴趣区池化模块,通过加入少量的参数和计算量以学习目标的几何形变。实验结果表明,该文提出的模型针对密集区域的车辆目标具有较好的检测性能。     

Helical‐Like 3D Ultrathin Piezoelectric Element for Complicated Ultrasonic Field

The developments of personalized medicine, ultrasound imaging, and contactless “microscopic handle” techniques are pushing ultrasonic transducers toward features of high frequency, device miniaturization, and even novel function. However, the conventional ultrasonic transducer has severely limited the development of novel ideas for applications due to its ordinary ultrasonic field. Although transducer arrays and monolithic acoustic holograms are capable of producing the complicated ultrasonic field, it is still difficult to achieve high frequency, device miniaturization, and novel function simultaneously. Here, a simple but effective approach is introduced that aims at reconstructing the complicated and high‐frequency ultrasonic field via a compact single‐element ultrasonic transducer. The 3D ultrathin piezoelectric element with a complex configuration is demonstrated theoretically and experimentally to produce the desired complicated ultrasonic field. With helical‐like configuration, the single‐element ultrasonic transducer offers efficient noncontact trapping and manipulation of suspended microparticles and biological cells. Moreover, its strong trapping capability leads to the 3D stacking of microparticles, which is a novel and interesting phenomenon achieved by a single‐element ultrasonic transducer. This work brings the possibility of a complicated ultrasonic field for achieving novel high‐frequency ultrasound applications through the design of smart structure ultrathin piezoelectric materials.     

宽光谱日夜两用摄像镜头设计

分析了宽光谱短焦距光学系统的像差特点,并给出该光学系统的传递曲线,同时介绍了采用Zemax设计的日夜两用微型视频摄像镜头,无需调焦,其结构型式为天塞物镜,实现了0.7视场其空间频率为50 lp/mm的调制传递函数均大于0.5,具有较高的分辨率.     

Hilbert-Huang变换的自适应频率多分辨分析研究

Hilbert-Huang变换方法能自适应地提取非平稳数据的局部均值曲线,将复杂的叠加信号分解成有限数量的、且有物理意义的内蕴模式分量函数,从而得到有意义的瞬时频率和希尔伯特时频谱.它是一种局域波分析方法.其特点是比小波分析有更高的时频分辨率,没有Wigner-Ville分布的交叉项,特别适合分析非平稳数据.本文根据Hilbert-Huang变换的原理,推导出内蕴模式函数的递推表达式,给出了希尔伯特谱的最高频率分辨率,首次提出了一种新的的自适应频率多分辨分析原理和方法,从而完善了局域波分析的理论.     

基于动态噪底跟踪的宽带接收机信号检测

对不平坦噪声基底的准确估计是宽带接收机信号检测的关键,传统的宽带检测多采用基于迭代形态学运算的静态噪底估计方法,不同时刻的估计结果之间互不相关,存在分辨率低、迭代耗时和时间连续性差等问题。针对上述问题,提出了一种动态噪底跟踪方法。首先建立带内各频点噪声基底的时变模型,然后将其作为系统状态引入卡尔曼滤波框架进行时间维度的噪底连续估计,同时结合频率维度的高斯平滑,实现了时间-频率两个维度的噪底跟踪。通过实采宽带信号验证,所提算法相较传统方法在噪底估计分辨率、连续性、计算效率等方面均有明显提升。     

Two-dimensional digital filters for geophysical applications: A simple design method leading to an easy implementation

A simple procedure for the design of two-dimensional digital filters will be presented. Its main interest is in the field of geophysical signal processing, since the design implies in these cases simple structures for the implementation. The 2-D problem is reduced to one, two or complicated cases to several 1-D problems. By 3 examples, relevant in geophysics, the power of this method will be demonstrated. The design is applicable for arbitrary ideal frequency responses, however the simple realization will be lost in general. The result is a suboptimal filter, which can be used, if desired, as an initial solution for an L_∞-approximation. However, the efficiency of the presented method is established by the fact that the design and implementation go hand in hand and are adapted to the special problem under consideration.     

基于对标学习的智能优化算法

科研、工程和管理中的很多问题都可以转化为优化问题。应用于这些优化问题的各种方法本身就是各种模型,设计不同的方法即设计不同的模型。将标杆管理理念建模成为一种用于单目标优化问题的元启发式搜索方法。基于奥卡姆剃刀原则,摒弃了复杂的操作算子的概率调优规则,用一个简单的框架来组织核心算子,从而达到许多组合算法的搜索效果。     

Radio tomography of the ionosphere

An overview of tomographic approaches to ionospheric remote sensing in the radio-wave range is provided. Tomographic methods are divided into deterministic and statistical ones. Deterministic tomography problems can be subdivided into ray radio tomography and diffraction radio tomography. The statistical radio tomography approach is used when it is necessary to reconstruct the statistical structure of a great number of inhomogeneities, on the basis of measurements of field statistics (instead of one realization of the reconstruction of an inhomogeneity). Methods of solving radio tomography problems, and their connection with inverse scattering problems, are considered. The results of some initial experiments that show the possibilities of the radio tomography approaches are described. Future applications and problems are discussed     

Coupling of finite element and moment methods for electromagneticscattering from inhomogeneous objects

A hybrid formulation which combines the method of moments (MM) with the finite element method (FEM) to solve electromagnetic scattering and/or absorption problems involving inhomogeneous media is discussed. The basic technique is to apply the equivalence principle and transform the original problem into interior and exterior problems, which are coupled on the exterior dielectric body surface through the continuities of the tangential electric field and magnetic field. The interior problem involving inhomogeneous medium is solved by the FEM, and the exterior problem is solved by the MM. The coupling of the interior and exterior problems on their common surface results in a matrix equation for the equivalent current sources for the interior and exterior problems. Combining advantages of both methods allows complicated inhomogeneous problems with arbitrary geometry to be treated in a straightforward manner. The validity and accuracy of the formulation are checked by two-dimensional numerical results, which are compared with the exact eigenfunction solution, the unimoment solution, and Richmond's pure moment solution