A2 paradox in statistical processing of weak signals

A statistical method for the detection and conversion of weak ultrabandwidth radar signals in a mode of small sample size is investigated by means of modeling and analytic calculations. The newly discovered and demonstrated phenomenon in signal processing is called the A2 paradox.     

Adaptive spatial processing of electromagnetic field signals in antenna arrays

The expressions for an adaptive spatial filter and Capon??s direction-finding profile have been obtained using the maximum likelihood method. It has been shown that Capon??s method lies in the maximization of the energy of the output signal of the adaptive spatial filter. Adaptive methods for spatial localization of radiation sources with filtering of the stationary field component are proposed. The problems of the taking polarization of the electromagnetic field into account are considered. The results of a numerical simulation are presented.     

Adaptive processing for beamforming with coherent interference using uniform circular arrays

The paper deals with the problem of adaptive array beamforming using a uniform circular array (UCA) in the presence of coherent interference. The well-known scheme of spatial smoothing (SS) widely used to tackle the coherent problem in the cases of 1-D uniform linear array (ULA) and uniform rectangular array (URA) cannot work for the UCA case. This is mainly due to the fact that the direction vector of each signal received by a UCA does not possess a Vandermonde structure. In this paper, we present a method based on subarray beamforming in conjunction with an averaging scheme to effectively mitigate the effect due to coherent interference in the UCA case. Theoretical analysis regarding the validity of the proposed method is also presented. Several simulation examples are provided for showing the effectiveness of the proposed method.     

基于受控Lorenz系统的微弱脉冲信号检测

利用Lorenz系统的参数非共振激励混沌抑制原理,实现强噪声背景下微弱周期脉冲信号的检测．将频率远大于系统特征频率的脉冲信号作为系统内置激励信号,根据平均法和重整化方法得到受控Lorenz系统与原系统的参数等效关系,并确定使系统由混沌状态突变为周期状态的检测参数临界值．仿真结果表明此系统可以达到较低的信噪比工作下限．此方法可根据理论分析结果预测参数临界值范围,检测方式简便易行,适于在目标探测和故障诊断领域推广应用．     

多通道微弱电压信号同步采集系统开发

针对微纳尺度测量领域对微弱电压信号多通道同步采集的需求,开发了一种基于ADS1274的微弱电压信号同步采集系统。该系统以A/D转换模块为核心,以C8051F120高性能微处理器与外围电路构成控制单元,具有4通道电压同步采集功能。通过设计液晶显示电路,可实时显示测量值。实验结果表明,该系统可实现预定功能,分辨率达到亚微伏级。     

强光干扰下的火焰前景提取技术研究

火焰前景提取是视频型火灾检测算法的重要步骤,也是后续火焰特征识别算法的基础。针对现有火焰前景提取算法在强光干扰下或在背景与火焰颜色相近时无法正确提取火焰前景的问题,提出一种新的火焰前景提取算法。首先通过计算瞬时运动区域和火焰颜色区域来确定初级疑似火焰区域;然后对初级疑似区域和非疑似区域制定不同的背景建模策略来得到运动前景;最后由运动区域和高亮区域得到最终的火焰前景。与4种已有的火焰前景提取算法的对比实验表明,该算法在复杂背景下的火焰前景提取准确率为96.2%,远高于现有算法;能适应不同类型的复杂背景,并且满足实时性要求。     

Intelligent processing of multimedia signals

Multimedia Tools and Applications -     

Two weak pursuers in a game against a single evader

We consider an antagonistic differential game where the first player controls the actions of two pursuers that aim to minimize, at a given time instant their miss with respect to an evader. The second (maximizing) player is identified with the evader. We study the case when dynamic capabilities of pursuers are less than the capabilities of the evader. We propose a quasioptimal control method for the first player with switching lines. We also show modeling results.     

Optimal filtering of a random background in image processing problems

We describe a recurrent construction procedure for mean-square optimal linear spatio-temporal filtering of a random background, which makes it possible to construct filtered frames using explicitly written compact analytical expressions.     

基于Duffing振子的MEMS陀螺微弱周期信号检测

Duffing混沌振子系统对周期小信号具有敏感性,对噪声具有免疫性。对此进行了特性分析,讨论了振子方程参数变化带来的影响。对Duffing振子微弱信号检测的原理进行了实验验证,以LCG50陀螺为例,用Duffing振子检测方法对其周期误差信号进行了检测和分析,基于检测结果设计了FIR滤波器对MEMS陀螺周期误差信号滤波,结果表明:Duffing振子方法在MEMS陀螺微弱信号检测与信号处理中的可行性和有效性。     

用阻塞矩阵法实现弱信号二维DOA估计

基于矩形平面阵列,将一维阻塞矩阵推广至二维,提出了一种强干扰背景下弱信号的二维DOA估计算法。首先构造二维阻塞矩阵对阵列接收数据进行预处理,抑制掉已知方位强干扰,再进行弱信号的谱估计。算法提高了弱信号的检测概率和估计精度。理论分析和仿真实验表明了该算法的有效性和正确性。     

图像的自适应粗糙集边界检测

粗糙集是解决模糊性、随机性、复杂性和不可分辨性问题的有效工具。利用粗糙集理论,给出了一种基于粗糙集的图像边界检测算法,研究了算法的基本原理、实现和复杂度。实验结果表明该算法在计算速度、抗噪能力、鲁棒性、可控能力和检测效果等方面,均优于其他边界检测算法。     

Simulation of atomic quantum dynamics in combined intense laser and weak electric fields

Numerical simulations are presented for a two-dimensional model of a hydrogen-like nitrogen ion in such intense laser fields that the electron velocity becomes non-negligible to that of light. With increasing laser field intensity, the role of its magnetic field component becomes more significant and a notable magnetically induced electron drift in laser propagation direction occurs. We show that this drift can be controlled to some degree by applying additional static or oscillating electric fields polarized in the laser propagation direction.     

复杂场景下自适应背景减除算法

目的 复杂场景下的背景减除是智能视频监控研究领域的研究重点和热点之一.针对混合高斯模型中高斯分布个数固定和参数初始化粗糙问题,提出一种应用于复杂场景中的基于混合高斯模型的自适应背景减除算法(AMGBS).方法 通过灰度值归类算法自适应调整模型的高斯分布个数,使得背景模型能够适应场景的变化,并且结合在线 K均值(online K-means)算法和在线期望最大化(online EM)算法初始化混合高斯模型参数.结果 针对灰度值统计结果调整高斯分布数,以及采用优化参数初始化过程,实验表明,本文方法的平均查准率和平均查全率比传统的混合高斯算法高出10%左右,比其他改进的混合高斯算法高出2%左右.结论 提出一种新的自适应背景减除算法,针对灰度值统计结果调整高斯分布数,以及采用优化参数初始化过程.实验结果表明,该方法对复杂场景有较强的适应能力,能够有效快速地完成背景减除,进而实现运动目标的提取.     

基于同源性检验的干扰信号识别方法

针对强干扰背景下管道泄漏声波检测产生的误报和漏报,提出一种基于同源性检验的干扰信号识别方法。将干扰信号和泄漏信号均作为异常信号,在基于迭代计算的异常信号自适应提取和一对一互相关延时估计的基础上,找出定位在站点的上下游异常信号并计算出相应的传播衰减特性。以同源信号的传播衰减频域特征和互相关系数为特征向量,建立异常信号同源性检验的支持向量数据描述(SVDD)诊断模型,实现站上干扰信号的识别和分离。对实际原油输送管线历史数据的离线测试结果表明:提出的方法能够可靠识别与分离干扰信号,有效减少系统的误报和漏报,并提高泄漏检测的可靠性和定位精度。     

Modification of the statistical method for detecting weak noisy signals

In this paper, a modification of the statistical method for detecting noisy signals is studied; this modification gives an increased signal-to-noise ratio. Corresponding computational formulas are obtained.     

Adaptive technology of the sampling of noise-corrupted signals

It is shown that, for certain industrial objects, the range of the spectrum of technical parameters can vary in time depending on the operating regime, the environment, the raw material properties, the appearance of defects which can appear, and other operating conditions. A technology that makes it possible to adapt the sampling step to the spectrum of the signal range is proposed. This technology accounts for the metrological parameters of analog-to-digital converters used for this purpose.     

混沌背景中微弱信号参数估计新方法

本文提出一种基于单向耦合同步的混沌背景中谐波频率估计的新方法。该方法把混沌背景中的谐波频率估计问题转变为同步误差中的谐波频率估计问题,改善了信噪比,在混沌背景中存在强随机噪声情况下,仍能估计出谐波信号频率。仿真实验表明,该方法简单有效,计算量小,且估计效果要优于RBF神经网络方法。     

一种新的背景预测方法在红外弱小目标检测中的应用

针对空中红外弱小目标的检测,提出了一种新的背景预测方法。该方法对云层边缘区域的点采用亮暗点分类,寻求最相似点的方法进行预测;对非边缘区域的点采用基本背景预测法进行预测;最后经过背景对消和阈值分割,将弱小目标检测出来。实验结果表明,该方法能够提高对起伏背景预测的准确性,减小由于云层边缘预测不准确而引起的虚警,从而能够更加有效地检测到弱小目标。     

Fuzzy rough set techniques for uncertainty processing in a relational database

This paper concerns the modeling of imprecision, vagueness, and uncertainty in databases through an extension of the relational model of data: the fuzzy rough relational database, an approach which uses both fuzzy set and rough set theories for knowledge representation of imprecise data in a relational database model. The fuzzy rough relational database is formally defined, along with a fuzzy rough relational algebra for querying. Comparisons of theoretical properties of operators in this model with those in the standard relational model are discussed. An example application is used to illustrate other aspects of this model, including a fuzzy entity–relationship type diagram for database design, a fuzzy rough data definition language, and an SQL‐like query language supportive of the fuzzy rough relational database model. This example also illustrates the ease of use of the fuzzy rough relational database, which often produces results that are better than those of conventional databases since it more accurately models the uncertainty of real‐world enterprises than do conventional databases through the use of indiscernibility and fuzzy membership values. ©2000 John Wiley & Sons, Inc.