以多道面波分析技术(MASW)为代表的主动源面波方法已经在地表勘探领域获得越来越多的应用.准确的面波相速度频散成像是利用主动源面波法进行近地表横波速度反演的必要条件.本文提出了一种新的主动源面波频散成像方法—CCPS(Cross-Correl...以多道面波分析技术(MASW)为代表的主动源面波方法已经在地表勘探领域获得越来越多的应用.准确的面波相速度频散成像是利用主动源面波法进行近地表横波速度反演的必要条件.本文提出了一种新的主动源面波频散成像方法—CCPS(Cross-Correlation and Phase-Shifting)法.首先,将单炮面波记录由时空域变换到频率空间域并消去振幅谱的影响,得到归一化频谱.然后,依次将每道信号与整个记录进行互相关的同时进行相速度扫描叠加.最后经过一次求和过程即得到最终的频散图像.通过理论数据、实际工程地震面波资料和石油勘探面波资料比较了普通相移法和CCPS法的频散成像效果.研究表明:新方法相对于普通相移法而言,明显提高了频散图像的质量,相速度聚焦性能和背景噪声压制能力有显著改善.展开更多
为解决扰动监测系统定位精度低的问题,基于对光纤马赫-曾德尔干涉的研究,设计了改进型双马赫-曾德尔分布式光纤扰动监测系统。利用双马赫-曾德尔光纤传感系统光程差定位原理,通过互相关算法估算光程差导致的时间差确定扰动点。淹没于高...为解决扰动监测系统定位精度低的问题,基于对光纤马赫-曾德尔干涉的研究,设计了改进型双马赫-曾德尔分布式光纤扰动监测系统。利用双马赫-曾德尔光纤传感系统光程差定位原理,通过互相关算法估算光程差导致的时间差确定扰动点。淹没于高频噪声的扰动信号经自主设计的信号预处理电路,采用低通巴特沃斯滤波器滤除3.3 k Hz以上高频噪声,通过嵌入式采集与处理模块对得到的数据进行平滑滤波,提高了扰动信号的相关性,有效减小了定位误差。通过多次重复测试和数据分析结果表明,系统定位误差约为10 m,可用于扰动实时监测。展开更多
An improved phase averaging method based on cross-correlation of the instantaneous velocity field determined by TR-PIV measurements is proposed in this article. A Time-Resolved Particle Image Velocimetry （TR-PIV） is...An improved phase averaging method based on cross-correlation of the instantaneous velocity field determined by TR-PIV measurements is proposed in this article. A Time-Resolved Particle Image Velocimetry （TR-PIV） is used to measure the two-dimensional wake behind the square cylinder. The phase signals associated with the deterministic appearance of the Karman vortex street are obtained by calculating the correlation matrix of the low-pass filtered velocity field, and can provide the complete information of the phase-averaged wake flow. The results show the advantages of the enhanced methodology in extracting the quasi-periodic flow patterns related to the shedding coherent structures without using additional reference signals.展开更多
文摘以多道面波分析技术(MASW)为代表的主动源面波方法已经在地表勘探领域获得越来越多的应用.准确的面波相速度频散成像是利用主动源面波法进行近地表横波速度反演的必要条件.本文提出了一种新的主动源面波频散成像方法—CCPS(Cross-Correlation and Phase-Shifting)法.首先,将单炮面波记录由时空域变换到频率空间域并消去振幅谱的影响,得到归一化频谱.然后,依次将每道信号与整个记录进行互相关的同时进行相速度扫描叠加.最后经过一次求和过程即得到最终的频散图像.通过理论数据、实际工程地震面波资料和石油勘探面波资料比较了普通相移法和CCPS法的频散成像效果.研究表明:新方法相对于普通相移法而言,明显提高了频散图像的质量,相速度聚焦性能和背景噪声压制能力有显著改善.
文摘为解决扰动监测系统定位精度低的问题,基于对光纤马赫-曾德尔干涉的研究,设计了改进型双马赫-曾德尔分布式光纤扰动监测系统。利用双马赫-曾德尔光纤传感系统光程差定位原理,通过互相关算法估算光程差导致的时间差确定扰动点。淹没于高频噪声的扰动信号经自主设计的信号预处理电路,采用低通巴特沃斯滤波器滤除3.3 k Hz以上高频噪声,通过嵌入式采集与处理模块对得到的数据进行平滑滤波,提高了扰动信号的相关性,有效减小了定位误差。通过多次重复测试和数据分析结果表明,系统定位误差约为10 m,可用于扰动实时监测。
基金supported by the National Natural Science Foundation of China (Grant Nos.50606024,50711140398)
文摘An improved phase averaging method based on cross-correlation of the instantaneous velocity field determined by TR-PIV measurements is proposed in this article. A Time-Resolved Particle Image Velocimetry （TR-PIV） is used to measure the two-dimensional wake behind the square cylinder. The phase signals associated with the deterministic appearance of the Karman vortex street are obtained by calculating the correlation matrix of the low-pass filtered velocity field, and can provide the complete information of the phase-averaged wake flow. The results show the advantages of the enhanced methodology in extracting the quasi-periodic flow patterns related to the shedding coherent structures without using additional reference signals.
