Combined digital filtering of harmonic content of phase-shift keyed signals in the problem of estimation of the time delay

We propose a two-step method for digital filtering of phase-shift keyed signals filtering in the problem of determination of the time delay during the multichannel propagation. The first step is realized as an information-optimal linear filter with complex coefficients, while the second step, as a quadratic filter based on the minimum-variance criterion. The e.ciency of the proposed method is demonstrated for short PSK signals with various carrier frequencies against the background of additive and multiplicative noise. The developed algorithm can easily be implemented in real time on the basis of a digital signal processor. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 50, No. 3, pp. 255–264, March 2007.     

Analysis on the Development of Digital Economy in Guangdong Province Based on Improved Entropy Method and Multivariate Statistical Analysis

The lack of adequate indicators in the research of digital economy may lead to the shortage of data support on decision making for governments. To solve this problem, first we establish a digital economy indicator evaluation system by dividing the digital economy into four types: “basic type”, “technology type”, “integration type” and “service type” and select 5 indicators for each type. On this basis, the weight of each indicator is calculated to find the deficiencies in the development of some digital economic fields by the improved entropy method. By drawing on the empowerment idea of Analytic Hierarchy Process, the improved entropy method firstly compares the difference coefficient of indicators in pairs and maps the comparison results to the scales 1–9. Then, the judgment matrix is constructed based on the information entropy, which can solve as much as possible the problem that the difference among the weight of each indicator is too large in traditional entropy method. The results indicate that: the development of digital economy in Guangdong Province was relatively balanced from 2015 to 2018 and will be better in the future while the development of rural e-commerce in Guangdong Province is relatively backward, and there is an obvious digital gap between urban and rural areas. Next we extract two new variables respectively to replace the 20 indicators we select through principal component analysis and factor analysis methods in multivariate statistical analysis, which can retain the original information to the greatest extent and provide convenience for further research in the future. Finally, we and provide constructive comments of digital economy in Guangdong Province from 2015 to 2018.     

Method for superposing reconstructed images from digital holograms of the same object recorded at different distance and wavelength

A method for allowing direct perfect superimposition and comparison of Fresnel-transform reconstructions of digital holograms recorded of the same object at different distances and wavelengths is proposed and demonstrated. The method takes into account the dependence of the reconstruction pixel on the distance and the wavelength by the Fresnel-transform algorithm. The method avoids the need for image scaling at the end of the reconstruction process that usually is performed in multi-wavelength digital holography. Demonstration is given by superposing the numerical reconstructions of holograms recorded at different distances and wavelengths. The method can be potentially very useful for real-time monitoring in biological processes or for recognition and ranging by multiple wavelengths of a target with fast movements or finally for very fast investigation and study of very fast processes.     

基于System Generator的射频直接带通采样MRI信号接收方法

本文将软件无线电技术应用于磁共振成像（Magnetic Resonance Imaging，MRI）信号接收，提出了射频直接带通采样MRI信号接收的方法.基于此接收方法设计了一种MRI信号数字解调方法，该方法利用Xilinx公司推出的数字信号处理（Digital Signal Processing，DSP）设计开发工具——System Generator实现，同时设计验证了能够灵活实现数字下变频（Digital Down Conversion，DDC）功能的DDC系统.仿真与实验平台均验证了该接收方法的正确性和有效性.     

一种基于二元位相加密的大信息量数字全息水印

研究了一种基于二元位相加密的大信息量数字全息水印方法,对需隐藏的水印信息用二元位相编码,然后再用2台阶位相密钥进行加密,作为水印插入宿主图像中,解码后得到了高质量的水印结果.与平面波照明数字全息水印相比,采用位相密钥数字全息水印有效地提高了水印提取的安全性和相对光学效率,并保持了对大信息量水印的提取质量,解码过程不依赖于原图像. 计算和分析了二元位相密钥的空间分布对水印信息提取质量的影响,计算结果验证了理论的正确性.     

Estimation of parameters of motion of a moving sound source by digital processing of a set of Doppler-shifted underwater acoustic signals

A method is proposed for estimating the parameters of motion of a moving sound source on the basis of digital processing of Doppler-shifted underwater acoustic signals received by a set of hydrophones. A two-step approximation algorithm is used. An example of implementing the method of estimating the parameters of motion is presented for a two-hydrophone receiving system. Errors in estimating the parameters by means of the proposed method are considered.     

基于数字图像处理技术的人脸检测算法研究

为了提高人脸检测的准确性及检测速度,需要对基于数字图像处理技术的人脸检测算法进行研究。使用当前方法进行人脸检测时,需要提取脸部特征数目较多、检测速度过慢,降低人脸检测效率。为此,提出一种基于数字图像处理技术的人脸检测算法。该方法首先获取人脸数字图像,通过拉开数字图像的灰度间距,使数字图像灰度均匀分布,进而提高数字图像对比度,使图像更加清晰,再通过Wiener维纳滤算法对处理后的数字图像进行图像平滑去噪,在此基础上使用Robert边缘检测算子方法对数字图像人脸边缘每个像素点检测,得到数字图像中人脸边缘的基本图像,将其输入到计算机数字图像处理系统中进行识别检测。实验仿真证明,所提算法在检测速度及准确性等方面具有明显的优势。     

L曲线方法在地基红外高光谱反演温度廓线中的应用

利用地基红外高光谱辐射数据可以反演得到高时间分辨率的边界层大气温度廓线。目前的AERIoe最优化反演算法相比于传统的“剥洋葱”算法有较大的改进,且对初值的依赖程度较低。但AERIoe算法中正则化算子的选择对反演结果的稳定性和反演时间有重要影响。目前主要采用经验的方法选择正则化算子,迭代步数较多,耗费大量的计算时间。提出了利用L曲线方法代替经验法选取正则化算子的改进方案,以提高AERIoe方法的反演速度。改进后的算法通过绘制解范数和残余范数的二维曲线图,取其拐点作为最优的正则化参数,相比于传统的经验法有着更好的理论基础。采用2011年美国大气辐射测量计划中SGP站点的晴空大气红外辐射数据进行反演实验。结果表明,利用该方法得到的反演结果具有很好的稳定性、收敛性和精度。相比于经验的方法,利用L曲线方法获得的正则化算子反演温度廓线时的收敛速度更快,迭代步数较少,可以节约大量的计算时间;在反演精度方面,L曲线方法在边界层中上层的反演精度更高,1～3 km高度上温度廓线的RMSE值提高了大约0.2 K。     

The coherent digital processing of the output signal of the Snail gravitational antenna

The statistical problem of the synthesis of a digital processing algorithm for the output signal of the Snail resonant gravitational antenna by analog prototype is considered. The discretization step in the ADC-DAC system is selected on the basis of the Kotelnikov theorem (a sampling theorem) for quasi-harmonic signals.     

实现FTIR光谱仪动镜扫描的全数字控制研究

动镜扫描是导致FTIR光谱仪动态测量误差的主要因素,其运动的平稳性直接制约着测量光谱的信噪比,并影响到后续光谱定性定量分析的精度,对FTIR光谱仪整体性能优劣有举足轻重的作用。针对传统基于模/数混合设计的动镜运动控制系统的复杂性,研究了一种简洁实效的全数字控制方法,将动镜运动产生的正交编码信号A和B送入数字逻辑芯片CPLD,在该芯片内编写相应的位置和速度控制算法,生成两路PWM信号,再通过数字功率芯片驱动挂载动镜的音圈电机完成扫描。实验表明,该控制方法使动镜在匀速阶段的速度平均稳定性优于97.2%,可显著提高测量光谱信噪比,为FTIR光谱仪高精度定量分析提供保障。     

Method of state code matrixes in the realization of optical switching using Perfect Shuffle

Based on the Left Perfect Shuffle (LPS) optical communication network constructed by cascade multi-stage LPS interconnection, using Looping algorithm, any arbitrary sequence of the input signals can be realized. However, instead of obtaining the simultaneous state codes of the same level node switches through mathematical analytical expressions directly, only routing tags of each channel can be obtained through mathematical analytical expressions so as to draw out topological chart of the network to obtain the state codes implied in the chart. Thus, the states of the switches cannot be directly programmed and controlled by computer in practical application. In this paper, based on the Looping algorithm, a method of stage code matrixes is presented to resolve this problem. By using the method, the simultaneous state codes of the same level’s four node switches can be directly obtained, which is convenient for the computer to provide controlled signals needed to finish the permutation for each node switch. The method of stage code matrixes provides further theoretical basis for the realization of optical switching by integration of Perfect Shuffle and high-speed optical switches.     

基于BEPCⅡ数据的数字束流位置测量器算法离线分析

介绍了数字BPM算法的原理和架构,并基于高能物理研究所自制的数字BPM硬件平台获取了BEPC Ⅱ束流流强为600 mA条件下的ADC采样数据。然后在MATLAB环境中设计了NCO模块、CIC滤波器、FIR滤波器以及BEPC Ⅱ束流逐圈位置数据计算模块,并给出了各模块的具体设计参数。最后通过实际ADC数据对各算法模块进行检验,给出了各模块处理后的频域分析结果,并得到了实际束流下水平方向和垂直方向上的逐圈位置分辨率分别为4.55 μm和4.28 μm,为FPGA在线算法的实现与优化提供了可靠的理论依据。     

基于拟牛顿法的连铸结晶器热传导反问题求解

在实际的工业过程中,热传导反问题广泛的存在于各个应用领域。由于连铸的生产环境恶劣,给连铸钢坯的测温造成了很大的困难,导致连铸结晶器热传导反问题的求解是很困难的。在研究了热传导反演算法的基础上,基于连铸结晶器的有限的测量点,通过热传导反演算法可以求出结晶器的热流密度,给连铸的优化和控制提供依据。在建立了连铸热传导反问题模型的基础上,提出了基于拟牛顿法的连铸结晶器热传导反问题求解的改进算法,该算法可以有效的利用当前搜索过程中的信息,通过近似目标函数的二阶导数来加快算法的搜索效率,采用了Wolf步长选择规则克服了算法收敛速率慢的缺点,并且该算法无需计算Hessen矩阵,能够有效降低计算的复杂度。实验结果表明该算法能够快速有效的求解该问题。该方法用于连铸结晶器热传导反问题是可行的、有效的。     

葡萄糖注射液中不溶性微粒的识别算法研究

针对传统人工目测法以及光阻检测法在葡萄糖注射液中不溶性微粒识别判断效率较低现象,提出了一种背景差预处理与改进的Mean Shift算法相结合的微粒识别算法。利用高分辨率数码相机采集在一定照度下葡萄糖注射液中不溶性微粒产生散射光的序列数字图像。对序列数字图像进行预处理及并标定数字图像有效检测区域。建立序列数字图像背景模型并对背景噪声与随机噪声进行抑制处理。采用改进的Mean Shift算法对葡萄糖注射液中不溶性微粒进行目标跟踪。通过对序列数字图像中被检测对象的分割与特征提取,实现了葡萄糖注射液中粒径在25μm以上不溶性微粒的识别。     

干涉型光纤传感器相位生成载波技术研究与改进

对干涉型光纤传感器的相位生成载波解调技术进行了研究.对PGC算法进行了数学推导和仿真计算,对数字低通滤波器进行了详细分析,给出了其影响PGC解调性能的原因及数字滤波器的设计方法.讨论了传感器干涉光强对PGC算法输出结果的影响,提出了改进的PGC算法,该算法可以有效的实现自动增益控制,消除干涉光强漂移对解调的影响,并大大减小由干涉光强引入的系统噪音;还可以在有限阶数低通滤波器的情况下,极大的增加系统可解调的大信号幅度,提高系统动态范围12 dB以上.     

中子数字图像几何不锐度校正算法研究

以中子数字成像系统的开发为背景,提出一种用于中子数字图像几何不锐度校正的图像复原算法。首先分析了中子数字成像的准直成像系统,得到引起中子数字图像几何不锐度的点扩展函数。据此,提出一种正则化的Lucy-Richardson(LR)算法,该算法利用贝叶斯(Bayes)最大后验估计理论研究了小波系数的双变量层间模型,推导出一种有效的小波降噪方法,并将小波降噪引入LR算法的迭代过程,此方法可有效解决原始LR算法的噪声放大问题。将改进的LR算法用于一个测试样品中子数字图像的几何不锐度校正,结果表明,该算法可以克服原始LR算法的不足,并优于频域小波域联合正则化图像复原算法。该方法还可以推广到其他图像复原的应用中。     

Analysis of holographic microscopy data to quantitatively investigate three-dimensional settlement dynamics of algal zoospores in the vicinity of surfaces

In this article we describe the technical aspects of digital in-line holographic microscopy to track multiple macrofouling Ulva linza zoospores simultaneously during their exploration of surfaces. Using an effective method of artefact suppression at the edges of holograms in combination with projection of volume reconstructions, a fast algorithm was developed which allows a reliable determination of a large number of subsequent spore positions. Thus, statistical analysis of swimming behaviour in the vicinity of surfaces becomes possible. Using glass surfaces as example, velocity and diving direction distributions are calculated and the swimming behaviour is statistically analysed. Diving direction analysis provides a straightforward way to determine segments within traces with surface contact. The presented method of data analysis allows high throughput analysis of holographic microscopy data and sets the basis for different applications including biofouling.     

A Bregman-Split-Based Compressive Sensing Method for Dynamic Harmonic Estimation

In order to overcome the spectral interference of the conventional Fourier transform in the International Electrotechnical Commission framework, this paper introduces a Bregman-split-based compressive sensing (BSCS) method to estimate the Taylor–Fourier coefficients in a multi-frequency dynamic phasor model. Considering the DDC component estimation, this paper transforms the phasor problem into a compressive sensing model based on the regularity and sparsity of the dynamic harmonic signal distribution. It then derives an optimized hybrid regularization algorithm with the Bregman split method to reconstruct the dynamic phasor estimation. The accuracy of the model was verified by using the cross entropy to measure the distribution differences of values. Composite tests derived from the dynamic phasor test conditions were then used to verify the potentialities of the BSCS method. Simulation results show that the algorithm can alleviate the impact of dynamic signals on phasor estimation and significantly improve the estimation accuracy, which provides a theoretical basis for P-class phasor measurement units (PMUs).     

基于DSP+FPGA的元器件焊接垂直度识别方法

为实现电路板上柱状元器件焊接垂直度的精准检测,设计了一款基于DSP+FPGA的垂直度识别系统。DSP承担核心算法任务,FPGA作为数据预处理单元,完成接口的逻辑、系统的互连以及数据通道。在硬件平台上嵌入了基于元器件形心配准的垂直度识别算法。首先对预处理的图像利用改进的Canny算法提取元器件的像素级边缘,并采用边缘跟踪算法去除噪点和干扰边缘并对元器件进行编号,在粗提取的边缘上用Zernike矩算法来精确定位元器件亚像素级边缘。在此基础上,提取元器件轮廓的最小外接矩形来修正边缘并得到每个元器件的形心坐标,最后根据形心的偏移距离来完成每个元器件垂直度的识别。实验结果表明,该垂直度识别系统的设计方案识别结果精度高,检测速度快,满足实时性要求,具有重要的实际工程意义。     

基于Facet模型的闪光图像边缘检测

针对闪光图像的特点,对经典边缘检测算子进行了分析,发现存在检测出的边缘粗和对噪声的干扰比较敏感的缺点,提出了一种基于Facet模型的爆轰实验图像边缘检测算法。该方法吸取了其它同类方法的优点,引进了正交基简化了运算,用离散正交多项式对图像每个像素的邻域作最佳曲面拟合,在此基础上使用整体梯度算子寻求二阶方向导数的零交叉点,最终提取边缘点。结果表明:该方法检测出的边缘细,并且光滑连续,对图像噪声干扰有较强的抑制能力,对于孤立的边缘能够给出较精确的定位。