共查询到18条相似文献,搜索用时 93 毫秒
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针对泄漏声发射信号的非平稳随机特性,进行了泄漏声信号可调Q因子小波变换(Tunable Q-Factor Wavelet Transform,TQWT)的理论分析和实验研究。首先通过对典型泄漏声信号的TQWT分析,研究品质因子和分解尺度对泄漏声特征提取的影响。然后根据峭度最大原则,优选出适合泄漏声信号分析的TQWT参数。在此基础上,提出了一种基于TQWT提取管道泄漏声特征分量的方法,并将提取的特征分量进行互相关分析用于管道泄漏定位。实验结果表明,利用该方法可以有效提取出泄漏声信号中的特征分量,从而更好实现泄漏定位,定位误差较小。该项研究工作为实际工程管道泄漏检测提供了可行的解决方案。 相似文献
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针对基于声发射技术的自来水管网泄漏检测定位方法,研究因泄漏而形成的声信号频率分布及不同泄漏量对频率分布的影响。实际泄漏检测时,通常采用互相关法估计泄漏信号到达不同传感器间的时间延迟实现漏点定位,因此,借助互相关分析法研究了管道的不同口径及泄漏信号传播距离对泄漏信号频率分布的影响。同时,泄漏声信号的传播不可避免要经过管道间的接口,因此分析了两种管道接口对信号频率成分的影响。进而为设计合理的管道泄漏检测过程提供依据,并为泄漏声信号形成及多种因素对泄漏声信号特征产生影响的机制研究奠定基础。 相似文献
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针对在军事演习或爆炸实验中对冲击波超压传感器位置的精确定位,设计了一种实时主动声定位系统。该系统由声信号发射系统、声信号接收处理系统和无线监控终端系统三部分组成。声信号发射系统与无线监控终端以单片机STC12C5A60S2作为核心控制器,接收处理系统以ARM9系列的S3C2440作为核心控制器。发射系统发射四种已知频率的声信号,接收处理系统接收并处理收到的四种声信号,然后把处理结果反馈到无线监控终端。通过实验表明,该系统在一定条件下,能够稳定地发射、接收并处理声信号,达到实时定位目标,并在200 m范围内将定位误差控制在厘米级内。 相似文献
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城市燃气在管道运输过程中存在很大的安全隐患,一旦发生危险,后果不堪设想,燃气管道泄漏的监测与定位意义重大。为解决目前大部分管道泄漏检测与定位方法存在的易受环境干扰、精度低、适用范围窄、计算难度较高等问题,提出了一种基于时延估计的光栅阵列(wFBG)管道泄漏检测与定位方法,该方法通过光栅阵列技术采集振动信号,根据采集到的泄漏振动信号时域、频域上的特征,首先通过基于短时能量分析的方法检测管道是否泄漏,然后对满足要求的信号片段进行峰值间多项式拟合获取泄漏信息到达的时刻,最后根据时间差定位泄漏点。实验结果表明,该方法能有效检测泄漏,并且在测量距离为40 m的情况下,定位误差在1 m左右。 相似文献
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为了提高火电厂电站管线漏电检测的准确性和实时性,并最大程度降低对管线的损坏,设计并实现了一种基于ASDX/ASCX的火电厂电站管线漏电无损检测系统。采用ASDX/ASCX传感器完成对电站管线漏电信号传播速度数据以及电站管线漏电信号所在管线高度数据等的采集,基于可编程逻辑控制器PLC(Program Logic Control,PLC),对采用传感器采集管线中的数据过程进行实时控制,通过实时分析采集的数据,进而实时的对管线进行无损检测,系统硬件设计给出了基于ASDX/ASCX三轴加速度传感器、ARM微处理器以及USB2085数据采集卡等硬件的设计原理,软件设计中,对PLC控制的软件平台选择及运行流程进行了详细设计,并给出了无损检测漏电信号TMS320VC5509A DSP处理流程。实验结果表明,系统控制误差在2%以内,比传统系统平均节能120J,运算效率提高22%左右。系统控制精度高,响应速度快,可靠性强,满足用户使用要求。 相似文献
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提出了一种光纤声发射传感器并构建传感系统实现变压器局部放电在线监测,利用传感光栅体积小,重量轻,灵敏度高和抗电磁干扰的特点,将传感器置于变压器内部实现局部放电声发射信号的测量。研究了传感光栅实现声发射应力波测量的机理,声发射信号引起传感光栅反射光谱发生漂移,导致特定频点处反射光强发生变化,通过反射光强的变化实现声发射信号的测量。构建声发射传感系统实验模型并提出了一种系统性能优化策略,使系统工作在传感光栅反射光谱上升或下降沿的半峰值频点处,从而保障传感系统具有良好的线性输出特性;研究传感系统工作点稳定技术,设计信号反馈回路自动跟踪反射光谱的漂移,保证系统稳定工作在传感光栅半峰值频点处,消除温度变化对传感系统测量精度的影响。将封装好的传感器用于变压器局部放电现场检测,结果表明,光纤光栅声发射传感器与压电传感器相比具有灵敏度高、动态范围宽等优点,可以实现变压器局部放电在线监测。 相似文献
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Leak Detection of Gas Pipelines Based on Characteristics of Acoustic Leakage and Interfering Signals
When acoustic method is used in leak detection for natural gas pipelines, the external interferences including operation of compressor and valve, pipeline knocking, etc., should be distinguished with acoustic leakage signals to
improve the accuracy and reduce false alarms. In this paper, the technologies of extracting characteristics of acoustic signals were summarized. The acoustic leakage signals and interfering signals were measured by experiments and the
characteristics of time-domain, frequency-domain and time-frequency domain were extracted. The main characteristics of time-domain are mean value, root mean square value, kurtosis, skewness and correlation function, etc. The features in frequency domain were obtained by frequency spectrum analysis and power spectrum density, while time-frequency analysis was accomplished by short time Fourier transform. The results show that the external interferences can be removed effectively by the characteristics of time domain, frequency domain and time-frequency domain. It can be drawn that the acoustic leak detection method can be applied to natural gas pipelines and the characteristics can help reduce false alarms and missing alarms. 相似文献
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When using laser interferometer to detect surface acoustic wave at fluid–solid interface, there are two factors which will cause the optical path length variation of the probe laser beam: interface deformation, and refractive index changes in fluid induced by acoustic leakage. Influence of acoustic leakage on laser interferometric detection for surface acoustic wave is researched here. A metal plate immersed in an infinite fluid is used as a physical model. Interface deformation due to laser-induced acoustic wave and pressure in fluid due to acoustic leakage are computed for select cases by finite element method. The optical path length variation caused by the two factors are calculated respectively and compared. The results show that the influence of acoustic leakage increases with the increasing acoustic impedance matching of fluid and solid, the peak-to-peak of influence degree increases linearly with the increasing acoustic impedance of fluid, and that decreasing the distance between the interferometer and interface can effectively reduce the influence of acoustic leakage. 相似文献
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本文介绍在数字声学测量分析系统中,通过双传声器信号互谱密度的计算进行声强及声功率测量的基本原理。该数学分析系统由微计算机,数字信号处理卡和A/D变换卡组成。在一个数字系统中,通过快速傅里叶变换(FET)进行互谱计算是十分有效的。本文着重介绍了,在声强的测量分析中对声强探头两传声器的固有相位差进行补偿的重要性和补偿方法,这是声强测量的重要环节。 相似文献
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In this paper, the decomposition of Rhodamine B (RhB) by hydrodynamic cavitation (HC), acoustic cavitation (AC) and the combination of these individual methods (HAC) have been investigated. The degradation of 20 L RhB aqueous solution was carried out in a self-designed HAC reactor, where hydrodynamic cavitation and acoustic cavitation could take place in the same space simultaneously. The effects of initial concentration, inlet pressure, solution temperature and ultrasonic power were studied and discussed. Obvious synergies were found in the HAC process. The combined method achieved the best conversion, and the synergistic effect in HAC was even up to 119% with the ultrasonic power of 220 W in a treatment time of 30 min. The time-independent synergistic factor based on rate constant was introduced and the maximum value reached 40% in the HAC system. Besides, the hybrid HAC method showed great superiority in energy efficiency at lower ultrasonic power (88–176 W). Therefore, HAC technology can be visualized as a promising method for wastewater treatment with good scale-up possibilities. 相似文献