Research on the imaging of concrete defect based on the pulse compression technique     

Li Chang-Zheng  Zhang Bi-Xing  Shi Fang-Fang  Xie Fu-Li 《应用地球物理》2013,10(3):337-348

When the synthetic aperture focusing technology (SAFT) is used for the detection of the concrete, the signal-to-noise ratio (SNR) and detection depth are not satisfactory. Therefore, the application of SAFT is usually limited. In this paper, we propose an improved SAFT technique for the detection of concrete based on the pulse compression technique used in the Radar domain. The proposed method first transmits a linear frequency modulation (LFM) signal, and then compresses the echo signal using the matched filtering method, after which a compressed signal with a narrower main lobe and higher SNR is obtained. With our improved SAFT, the compressed signals are manipulated in the imaging process and the image contrast is improved. Results show that the SNR is improved and the imaging resolution is guaranteed compared with the conventional short-pulse method. From theoretical and experimental results, we show that the proposed method can suppress noise and improve imaging contrast, and can also be used to detect multiple defects in concrete.  相似文献   

基于超声波合成孔径技术的钻孔成像方法     

汪进超  陶东新  黄燕庆  王川婴  韩增强  胡胜 《岩土力学》2019,40(Z1):557-564

随着地下空间开发的深入,钻孔岩壁上特殊区域的重视程度越来越高,为了克服传统超声波钻孔成像技术分辨率低的不足,提出一种基于超声波合成孔径技术的钻孔成像方法,提高钻孔图像的分辨率和图像质量。采用高分辨率的合成孔径SAFT成像技术综合处理大量的断面扫描回波信号,达到增强反射信号和抑制干扰信号的目的,使对应的岩壁特征区域回波更加突显,在该基础上提取出扫描断面回波信号的声幅和声时参数。综合声幅和声速参数的特征,提出了基于相关性的超声波钻孔图像重建原则,选择合适的成像数据点,在叠加不同深度的探测数据后形成了关注区域更加明显的钻孔重建图像。将该方法应用到了实际工程中,验证了该方法的可行性和准确性。  相似文献   

合成孔径聚焦超声成像方法研究     

杜英华  张聪颖  陈世利  孙芳  刘婧  靳世久 《海洋技术学报》2010,29(2)

合成孔径聚焦成像方法(SAFT)具有分辨率高、能在近场区工作的优点,是超声成像领域发展起来的新技术。文中介绍了合成孔径超声成像的原理,根据换能器阵列的声场辐射理论建立了数学模型,利用MATLAB对模型进行了数值仿真,最后进行了合成孔径超声成像实验。实验结果表明,合成孔径成像方法能够有效提高成像系统的分辨率。  相似文献