电气信号数字化检测技术研究

本文首先介绍了电气设备检测与故障诊断系统的组成,以及目前信号处理技术在电气设备检测中的应用状况,在此基础上分析了电气设备检侧技术的发展方向,总结出信号数字化在电气检测技术发展中的作用.希望本文的研究能够为电气设备检测技术的研究提供借鉴之据.     

电气信号数字化检测技术研究

本文首先介绍了电气设备检测与故障诊断系统的组成，以及目前信号处理技术在电气设备检测中的应用状况，在此基础上分析了电气设备检侧技术的发展方向，总结出信号数字化在电气检测技术发展中的作用。希望本文的研究能够为电气设备检测技术的研究提供借鉴之据。     

扩频信号的声光谱相关检测

传统检测扩频信号的声光技术,是将扩频信号建模为随机平稳过程,而扩频信号是被伪随机码调制的周期信号,应建模为循环平稳随机过程。基于声光技术与循环谱相关技术,提出了扩频信号的声光谱相关检测方法。建立了基于声光时间积分的声光谱相关检测模型,分析了当干扰瞄准扩频接收机时,扩频信号在循环频率α=1/Tc的循环谱,给出了循环谱峰的检测公式TcRs1/。仿真实验结果表明,与传统的声光技术检测扩频信号的功率谱相比,在光电检测阵列上检测的循环谱峰,谱峰旁瓣几乎为零,并可多获得约3dB的增益,表明声光谱相关检测方法具有更优异的检测和抗干扰性能。     

强背景干扰中微弱信号检测的新尝试

介绍１种检测强背景干扰中微弱信号的新方法，将其应用于医用Ｘ线滤线栅性能测试后，实现了检测手段的智能化；工作效率提高数１０倍以上。     

用多重自相关法检测微弱正弦信号

在LabVIEW平台的基础上，研究了利用多重自相关来检测微弱正弦信号的方法。此方法利用正弦函数的特性，通过多重自相关运算，再对信号进行频谱分析，就能准确检测出湮没于强大噪声的微弱正弦信号的频率信息和幅值信息。     

基于数字相关的弱信号检测方法的研究

通过对数字相关解调器工作原理的介绍,针对光纤结冰传感器的特点,提出了光纤结冰传感器微弱信号检测的总体设计方案.设计了数字相关算法,并以Labwindows8.0为基础进行了算法仿真,验证了相关算法检测微弱周期信号的可用性,并将数据采集板用于光纤结冰试验台架测量实际信号,检测结果与模拟相关器检测的结果一致.     

基于相位调制的多通道半色调信息隐藏技术

目的研究多通道半色调信息隐藏技术,通过相位调制技术,使彩色隐藏信息隐藏于不同色调的母版当中。方法在基础层,基于最小阈值矩阵原理,使用基于相位调制阈值矩阵加网技术定位各通道隐藏信息位置,并在母版中对正常图像部分网点的生长趋势进行改变,实现在位置上的调制,从而保证各通道信息良好的隐蔽性。结果使用相位调制技术可以达到多通道信息的隐蔽,达到彩色信息隐藏的预期效果。结论该技术有利于提高半色调加网信息隐藏技术在印刷防伪中的应用范围,提高半色调加网信息隐藏技术的防伪性能。     

声相关计程仪检测技术

声相关计程仪(Acoustic Correlation Log,ACL)检测技术用于对ACL在陆上进行功能检测。阐述了检测技术原理、检测方案以及检测平台的设计与实现。采用声呐阵对接检测的方案,可以连续对ACL完成一系列的检测。为了对70k Hz ACL进行功能检测,使用快速多通道并行的A/D、D/A模块,基于运行在PXI控制器的WINDOWS平台,开发了微软基础类库(Microsoft Foundation Classes,MFC)框架下的检测软件,搭建了完整有效的可视化检测平台。该检测平台可以完成对70 k Hz ACL的在载体功能检测,包括发射通道检测、接收通道检测以及串口输出检测等主要功能检测。检测平台使用便捷,性能稳健。经实验室测试证明,检测方案具备可行性,检测平台具有实用性。     

基于自相关和经验模态分解的微弱信号检测方法研究

本文针对自相关方法所存在的只能检测单一正弦信号和EMD方法易受噪声干扰的问题,提出将二者结合,先用自相关方法提高信噪比,而后用EMD方法分解信号,获取其中所包含的各有用信号成分,达到在低信噪比情况下检测出信号中有用成分的目的.仿真结果表明,该方法在低达-23dB的信噪比情况下仍能有效检测出仿真信号中包含的多频正弦成分,方法简单,效果明显.     

A method of data hiding in audio signal

Information hiding and secret communication is one of the most interesting and fascinating domains. This hiding method exploits some features of audio signals to be able to hide data from perception robustly. Every year researchers introduce their work and discuss how to make these techniques more and more robust against different types of attacks. In this article, we present an improved audio steganography approach that reduces distortion of the stego audio. Using the proposed algorithm, secret information is strongly protected from hackers and sent to its destination in a safe manner.     

A study of correlation technique on pyramid processed images

The pyramid algorithm is potentially a powerful tool for advanced television image processing and for pattern recognition. An attempt is made to design and develop both hardware and software for a system which performs decomposition and reconstruction of digitized images by implementing the Burt pyramid algorithm. In this work, an attempt is also made to study correlation performance on reconstructed images. That is, the reference image is taken from the original image and correlation is performed on expanded images of the same size. Similarly, correlation performance study is carried out on different pyramid-processed levels. In this paper results are presented in terms of RMS error between original and expanded images. Only still images are considered, and the hardware is designed around an i486 processor and software is developed in PL/M 86.     

复杂背景下多目标提取的高灵敏度方法

对电视经纬仪拍摄到的飞行小目标图像进行了归一化高斯模板相关。传统的模板相关方法不能将真假目标集合充分分离,导致真目标的漏检或引入虚假目标。基于模板相关的高斯函数拟合方法(Gaussian Function Fitting Method, GFFM),对模板相关所得到的目标集(含有真目标和假目标)中的每一个元素进行高斯函数拟合,并引入了一个更为灵敏的检验量—高斯函数拟合误差,可以将真假目标集合明显区分开,减小阈值确定的难度。实验表明:当相关系数阈值rth=0.8时,传统模板相关方法漏检率20%,虚警率40%;而GFFM方法则检出了所有真目标,且无虚假目标。     

A single-camera telecentric imaging stereo-digital image correlation system and its application to carotid pulse signal detection

Carotid pulse signal (CPS) is one of the most important biomarkers for evaluating cardiovascular risk. To realize easy-to-operate and accurate CPS detection, a single-camera telecentric imaging stereo-digital image correlation (stereo-DIC) system is established. The system uses a specially designed colour separation device and a single colour camera attached with a telecentric lens to record images of blue and red colours from different optical paths. By processing the recorded two sub-channel colour images using regular stereo-DIC algorithm, full-field 3D displacements of the skin on the neck directly over the carotid artery are obtained. The maximum fluctuations in the out-of-plane displacement direction are extracted as CPS, based on which velocity, acceleration and frequency can be further extracted. The performance of the established system was demonstrated by detecting the pulse signal of a volunteer before and after exercise.     

Quality factor analysis and optimization of digital filtering signal reconstruction for liquid ionization calorimeters

The Optimal Filtering (OF) reconstruction of the sampled signals from a particle detector such as a liquid ionization calorimeter relies on the knowledge of the normalized pulse shapes. This knowledge is always imprecise, since there are residual differences between the true ionization pulse shapes and the predicted ones, whatever the method used to model or fit the particle-induced signals. The systematic error introduced by the residuals on the signal amplitude estimate is analyzed as well as the effect on the quality factor provided by the OF reconstruction. An analysis method to evaluate the residuals from a sample of signals is developed and tested with a simulation tool. The correction obtained is showed to preserve the original amplitude normalization, while restoring the expected χ²-like behavior of the quality factor.     

A correlation method of estimating object coordinates in digital images from optoelectronic systems

A method is proposed for estimating the coordinates of an object invariant with respect to localization and size on digital images on the basis of the closeness function for nested arrays of images of the object and the standard. __________ Translated from Izmeritel’naya Tekhnika, No. 7, pp. 15–19, July, 2008.     

可见光图像背景起伏的平稳性和相关性分析

提出了单位根假设检验可见光图像背景起伏平稳性的方法,理论上证明了时空域变化的广义平稳性。该方法采用ADF假设检验,从时域和空域分析背景灰度的变化,利用线性回归的方法进行协整性检验,从而得出结论。在平稳的基础上,使用相关长度刻划背景起伏的时空域相关性,得到两个结论。(1)一维指数模型的时间相关长度分析表明背景起伏具有强时相关性。并且这种强相关性集中体现在像素点灰度均值和相邻的有限帧(1～2帧)。因此提出低阶AR模型(1～2阶)对这种特性进行描述,得到的模型参数可用于图像背景估计。(2)空间相关长度分析证实了背景起伏具有强的空域相关性。并且图像可以分割成若干个不相关的区域。总的来说,背景起伏具有时空域的双重平稳性和强相关性。     

Gabor小波时频分析在声发射信号处理中的应用

介绍Gabor小波时频分析的基本理论,用数值仿真举例验证Gabor小波时频分析可同时在时域和频域上来表征信号分布的特点。利用该方法可得到声发射源定位中传感器接收到的声发射信号在时域和频域上的分布,并用于区分声发射信号的传播模式和不同的信号组成,得到声发射波群的准确到达时间,从而提高时差定位的精度。     

The power of collective intelligence in a signal detection task

ABSTRACT

A novel spatial display for a classic signal detection problem was tested in an experiment with 30 naive volunteers and 2 experts, measuring the signal detection properties of a spatially organised display compared with temporally organised display. The collective performance of committees was also measured. The spatial display was quantitatively and qualitatively superior, resulting in a 4.6% increase in correctness of classifications and a 30.5% decrease in miss percentages. Qualitatively, 83% of participants preferred the new display. The collective receiver operating characteristic performance of the top half of the best performing naive participants was superior to that of most individuals and all experts. However, in an analysis that examined the value added of both the improved spatial display and the collective intelligence approach, the results demonstrated that the bulk of performance gains can be attributed to the improved design, as compared to the value of collective action, by roughly 2:1.     

Vibration signal modeling of a planetary gear set for tooth crack detection

In a planetary gearbox, there are multiple vibration sources, and the transmission path of vibration signals changes due to the rotation of the carrier. This study aims to model the vibration signals of a planetary gearbox and investigate the vibration properties in the healthy condition and in the cracked tooth condition. A dynamic model is developed to simulate the vibration source signals. A modified Hamming function is proposed to represent the effect of the transmission path. By incorporating the effect of multiple vibration sources and the effect of transmission path, resultant vibration signals of a planetary gearbox are obtained. Through analyzing the resultant vibration signals, some vibration properties of a planetary gearbox are revealed and the fault symptoms of sun gear tooth crack are identified and located. Finally, the proposed approach is experimentally verified.