Digital Filtering with Zero Phase Error

Aiming at the problem of phase error caused by normal filters in signal processing , summarizes the important meaning of digital filtering with zero phase error. Puts forward RRF Filtering which is a new way to realize digital filtering with zero phase error through reversing the time serials of the signal. Another way to realize digital filtering with zero phase error is suggested through reversing the time serials of normal filter. Testifies the way to realize digital filtering with zero phase error. Points out how to design the digital filter with zero phase frequency peculiarity. Solves the problem of phase error in DSP.     

Detecting EEG Sleep Spindles by Digital Filtering with Zero Phase Error

EEG signal is a kind of very complex non stationary signal. It is of important clinical values for using EEG most efficiently to distinguish all kinds of components in EEG or getting needed components to judge some pathology features effectively. The phase moving of the system can change the relative phase relation between the components in the inputed signal, so there can be a great change of the feature in time domain of inputed signal. The FRR and RRF digital filtering methods and their realization are discussed. By using these methods, the system can be of the feature of zero phase error, and the filtering of EEG signals with zero phase error can be realized. Based on the definition of sleep spindles, we can detect sleep spindles in time domain directly by using digital filtering with zero phase error.     

Noise-reduction of Digital Video Image Based on Time-recursive Filtering

With the analysis of the principle of time-recursive filter, the authors find that the nature of time-recursive filter is Weighted Mean Low-Pass filter and the relationship between filter coefficients and SNR and the artifact arising from the area where motion can not be tracked. One approach based on Automatic Control Method is proposed to solve the artifacts problem during the process of filtering and the authors designed the corresponding hardware based on FPGA and software respectively. The experimental results show that the time-recursive filtering is good at digital video image denoising and reduces the random noise of digital camera system.     

INFORMATION THEORY COMBINATION FOR ERROR ANALYSIS OF. SAMPLING-QUANTIZATION FOR DIGITAL MEASUREMENT SYSTEMS

This paper presents a new error analysis method based on the information theory. The analyse results of error of a digital measurement system will be illustrated more reasonably. This method is defined information theory combination, it will overcome the unintention between the uncertainty and the standard error of measuring results by traditional error analysis. On the basis of error spectrum analysis of sampling and quantization, an optimum digital filtering method is also presented in this paper. Simulation and testing show that the method is more resultful.     

Dynamic Characteristic of Micromachined Arrayed Microphone

Several kinds of microphone developed via silicon Micro Electro Mechanical System (MEMS) processes in recent years are investigated in this paper. The analysis and research of the merits and demerits of them show that: these conventional microphones mainly function as acoustic electric converters; the filtering against noise is implemented by a special filter circuit or a digital filter. Therefore, a design method for silicon micro array filter microphone is presented, where the filtering is achieved while converting signals. The effects of damping, silicon reed number and sensor element pair on dynamic characteristic are discussed; it follows that: Increasing damping can reduce microphone's sensitivity, while increasing silicon reed number can improve the sensitivity curve, furthermore, the implementation of the filter function is simultaneous with acquiring of the noise signal.     

Embedded Intellingent Dynamic Balance Testing System and Its Digital Filter Designing

A lot of information needs processing in time in dynamic balance testing, but the current intelligent dynamic balance instruments and the controlling box of dynamic balance machines made up ofsinglemicrocontroller do not meet the request.A method isgioen that the DSP-Microcontroller will be useddiredtlyinthe system of the intelligent dynamic balance instrumentby using embedded design technique. A principal and subordinate control system compose of DSP and microcontroller. The Microcontroller the system as a principal controller and the DSP implements digital filtering and FFT in dynamic balanc by means of its fast operation. The system develoyed according tothe method can do more analysisin time areaand frequency area.     

基于数字图像的玉米叶面积测量方法研究

【研究目的】以数字图像处理技术为基础,采用数码相机获取数字图像,建立使用Visual C++6.0开发的图像处理软件进行玉米叶面积测量的方法。【方法】首先,用数码相机拍摄挂在墙上粘贴着玉米叶片的参照白板来获得数字图像。然后提取图像的蓝色分量,利用中值滤波、膨胀、腐蚀等方法去除图像噪声,最大类间方差法自动阈值分割目标。接着进行区域标记与区域像素数统计,区域像素数结合图像分辨率就可以获得玉米叶片的实际面积。【结果】与直尺法所测结果具有很好的相关性,且比直尺法更精确,【结论】此种拍摄方法避免了几何畸变的产生。蓝色分量图像中目标和背景的灰度差异最大,便于分割。     

Calculation of Room Impulse Reponse and Acoustic Parameters by Finite-difference Time-domain Method

The administrator boundaries in room were modeled by digital filters of complex impedance in finite-difference time-domain (FDTD) method. Doors, windows and walls were described respectively by their complex impedance boundaries with digital filters. Impulse responses in a room were calculated with the FDTD model, and typical room acoustics parameters were obtained from the responses. The high correlation coefficients between the calculated and measured impulse responses and the good agreement in acoustic parameters show that sound field in room can be properly simulated by this FDTD model.     

乌兰察布地区马铃薯气候适宜度模型研究

为了定量描述马铃薯全生育期气候条件对其生长发育的适宜程度,利用内蒙古乌兰察布地区马铃薯观测资料和气象资料,采用多项式拟合方法构建了旬尺度的气候适宜度模型,建立了乌兰察布地区马铃薯生长全过程气候适宜度动态评价指标;并与株高和产量做了相关分析。结果表明：模型计算的气候适宜度与株高、产量存在显著正相关(P＜0.05);气候适宜度与株高的相关系数(R)在0.2881 以上（样本数位57 个）;气候适宜度与产量相关系数(R)在0.3633 以上（样本数位32 个）。本研究建立的旬尺度气候适宜度模型更为精细地描述了马铃薯气候适宜度的连续变化过程。     

基于多重滤波的高分辨率影像中线性特征提取

在高分辨率遥感影像中,线性特征提取一直是个难题,难主要表现在线性地物的边缘信息和噪音是一对矛盾体,边缘信息越明显,噪音就越强。本文利用高通滤波和统计滤波器,构建一个多重滤波,对IKONOS影像进行处理,通过三种不同高通滤波窗口对IKONOS影像处理结果的比对,得到一个较好的高通滤波处理窗口,处理后的IKONOS影像边界特征突出、区域模糊程度减小,目标地物大致轮廓已经区分出来,在此基础上对影像进行统计滤波处理,噪音明显减少,灰度分布更加集中和平滑,对高通滤波和统计滤波处理后的图像进行边缘检测,经过统计滤波后的图像较只进行高通滤波后的图像检测结果较好。实验结果表明：滤波后的影像噪音明显降低,信噪比明显提高,统计滤波后的影像,能够提高检测精度,表明了从高分辨率卫星影像上自动提取矢量信息的可行性,并为边缘检测的细化与跟踪处理提供了可靠的数据来源。     

Attack modeling using colored petri net and alerts correlation algorithms design

In order to improve the alerts quality and prediction capability of traditional intrusion detection systems (IDS), the advanced alerts correlation algorithms are proposed, which is based on attack scenarios modeling using colored petri net (CPN). The current analysis approach information filtering is updated to messages logic deduction by reasoning under the model. The alert and the attack are converted to two different parameters for computation. By means of transforming CPN model and calculating the minimal covering set, the algorithms for multi-step attack and cooperative attack are designed. The experimental alerts correlation analysis system (ACAS) is programmed. That experiment results indicate that these algorithms could be applied to improve the alerts quality and prediction ability of IDS effectively.     

基于机器视觉的棉花群体叶绿素监测

研究了利用机器视觉技术快速获取棉花群体叶绿素信息的方法，以期获得预测性高的颜色特征参数。结果表明，RGB颜色系统的G－R、(G－R)/(G+R)、r与g的组合值和棉花功能叶叶绿素含量、群体绿色指数呈极显著相关，而且拟合度较高；HIS颜色系统的Hue值和棉花功能叶叶绿素含量、群体绿色指数之间也极显著相关。对筛选出的两组模型进行检验，预测精度在84.07%~93.04%之间，推荐预测精度最高的G－R参数作为获取棉花群体叶绿素信息的最佳颜色指标。G－R预测叶绿素含量和群体绿色指数的模型分别为y=－1.3008+0.2125(G－R)－0.0038(G－R)2（R²=0.8669**）和y=－0.9726+0.1227 (G－R)－0.0016(G－R)²（R²=0.7487**）。     

中国基层乡镇政府行政过程中的数字鸿沟现象及解决对策

在全球信息化的发展建设中,对于“数字鸿沟”的广泛关注主要是在美国国家远程通信和信息管理局发表《在网络中落伍》的系列著名报告之后。数字鸿沟也是中国信息化建设中一个重要的研究课题,在基层乡镇的行政过程中,数字鸿沟现象客观存在。就中国数字鸿沟宏观大背景、乡镇的数字化建设和电子政务建设中的数字鸿沟以及乡镇数字鸿沟的弥合等做了简单分析和阐述。研究结果表明,在互联网使用与普及过程中,中国与发达国家之间、中国地区与地区之间以及群体与群体之间均存在数字鸿沟现象;中国基层乡镇政府行政过程中存在“外部”和“内部”两种形式的数字鸿沟,不能完全消除,只能尽力弥合,要以政府为主导,加强资金投入,积极借鉴国外先进经验,联合社会各界共同缩小数字鸿沟现象。     

基于数码图像的棉花叶片氮含量估测研究

为了探究利用数码图像处理技术诊断棉花氮素营养的最佳图像特征参数和最佳叶位,以‘新陆早53号’为材料,使用智能手机获取棉花不同叶位叶片图像,利用数字图像处理技术提取叶片图像颜色和纹理特征参数,分析叶片氮含量和特征参数的相关性,构建基于不同图像特征参数的氮含量估测模型。结果表明：颜色特征参数r、G/(B+R)、G/B和纹理特征参数COR、ASM与叶片氮含量相关性较好,相关性系数(r)均大于0.55。基于颜色-纹理综合特征参数构建的氮含量估测模型均优于基于颜色或纹理特征参数所建模型,其中倒4叶氮含量估测模型最优,模型决定系数(R²)为0.875、均方根误差(RMSE)为1.324、相对误差(RE)为8.09%。因此,利用数字图像处理进行棉花氮素营养诊断时,应选择的最佳图像特征参数为r、G/(B+R)、G/B、COR、ASM,应选择的最佳叶位为棉花倒4叶。     

中山市日平均气温时间序列的周期性与混沌性分析

用广东省中山市1955-2017年日平均气温时间序列分析周期与混沌性质。结果表明,功率谱为363d左右的年周期变化,为周期吸引子;是太阳直射点在南北移动导致。在滤去频率范围为0~0.005/d的年周期变化信息以后,功率谱呈连续谱;最大Lyapunov指数是正的,关联维数为10.1,表明高频气温变化部分具有混沌性。     

Application of Wavelet Denoising in Partial Discharge Online Monitoring of Transformer

Because of the strong interferences, such as discrete spectrum interferences (DSI), white noise and pulse-shaped interferences, it is still a difficult work to extract the partial discharge (PD) signal for transformer online monitoring techniques. Through deeply study on the automatic selection of threshold value and mother wavelet, the wavelet-based de-noising method for partial discharge signals is proposed. The analyzing results on simulation signal and field-measured signal indicate that the proposed method is fit for de-noising white noise but for DSI the comparably worse de-noising results is acquired. Hence it is predicted that good de-noising results will be achieved with the wavelet-based de-noising method combined with digital filtering method fitting for de-noising DSI.     

Performance and Method of Despread-spectrum in a Matched-filter

The archtecture and characteristic of digital matched filter circuit used for PN code synchronization are introduced and the method of PN code serial search acquition based on DMF has been researched in AWGN channel.Furthermore the detection probability and false alarm probability are derived for different correlation time(partitive period or whole period).Finally,the results of calculation and emulation are given in order to be employed as useful theoretical bases for reserching the acquisition performance of digital matched filter.     

基于无人机遥感图像的苎麻产量估测研究

本研究旨在探索一种利用无人机-RGB系统提取的苎麻株高和可见光图像光谱信息估测产量的新方法。试验于2019年在湖南农业大学耘园苎麻基地进行,利用无人机搭载高清数码相机获取二季苎麻苗期和成熟期的图像。首先利用Pix4Dmapper生成苎麻冠层2个生育期的数字表面模型和高清数码正射图像;然后基于数字表面模型采用"差分法"计算试验小区的平均株高(DSM-based H);基于正射图像提取试验小区RGB通道均值,进而计算遥感图像数码变量和植被指数,分析苎麻种质间的图像光谱表型性状和产量株高比性状的差异性与多样性;最后采用逐步回归方法建立苎麻产量预测模型,并对各项产量解释因子进行相关性分析。结果表明:(1)基于无人机-RGB系统遥感株高与实测株高显著相关(r=0.90),修正遥感株高的均方根误差为0.04 m。(2)苎麻产量与株高信息存在极显著相关性(r=0.91),而与图像光谱表型相关性不明显。(3)融合遥感图像株高和种质特征差异构建的苎麻产量估测模型精度较高, R²=0.85, RMSE=0.71。因此,基于无人机遥感图像的苎麻产量估测是可行的,这对苎麻种质特征评价和产...     

Research to Algorithms of the Regulators in Digital Control System

The R S T algorithms structures of usual digital regulator are researched and the results are given. It has solved the problem of relationship between the digital regulator and dynamical characterization of system. It is a direct and quick algorithm of the digital regulator based on the characteristic equation of control system. This algorithm is especially suitable for numerical simulation of control system which contains digital regulator.[WT5HZ]     

汽车转弯自动照明控制系统数据采集滤波方法

为了减少汽车转弯自动照明控制系统数据滤波处理中的延时,在滑动中值滤波方法基础上,提出了一种带补偿的限幅滑动中值滤波算法,通过补偿的方式跟随信号的变化趋势。该算法通过2个步骤完成滤波,先对数据进行带补偿方式的限幅处理,再进行滑动中值滤波处理。该算法综合了滑动中值滤波法的实时性以及限幅滤波法对偶然性干扰滤除的有效性,实现更准确的滤波。仿真与实测结果表明,与滑动中值滤波方法相比较,改进后的算法滤波能够实时地滤除数据中的干扰,处理时间可减少62%,滤波效果较好,且速度信号的数据滞后时间较短,实时性较高,满足系统设计要求。