基于合成孔径聚焦技术的混凝土断面二维成像方法研究
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摘要
针对提高混凝土结构超声无损检测分辨率的需要,提出了两种处理方法。在对低频B扫描数据进行合成孔径聚焦处理时,由于低频探测信号时间宽度大,波包会被拉伸,发生波包变形现象,为此,引入波包分解技术来解决这个问题。波包分解技术实质是用一些模型参数去描述检测信号,可以避免对回波信号所有采样点进行处理,不仅解决了波包变形问题,而且可以简化计算。对于实验中商用超声传感器引起的余振问题,提出一种数字滤波的补偿方法,通过水浸方式采集数据建立传感器系统补偿模型,用于实际检测信号中振铃的抑制,可提高成像的时空分辨率。数值仿真和实验结果证明,采用这两种方法后内嵌目标定位理准确,成像分辨率明显提高。
Two signal processing approaches are presented to improve imaging resolution in ultrasonic NDT of con- crete structures.When low-frequency B-scan data are processed by Synthetic Aperture Focusing Technique (SAFT), wavepacket will be further elongated because low-frequency detection signal covers a relative long period.Wavepacket Decomposition Technique (WDT) is introduced here to solve this problem.This method uses a few parameters to describe the original signal so that it can avoid the processing of the whole time history of signals.In practical mea- surement,ringing of commercial ultrasonic transducers also affects the discrimination of the detected signal,a method based on digital filtering is proposed to build the compensation model of transducer system.By eliminate the ringings with the filter,the spatiotemporal resolution of ultrasonic imaging is improved.Numerical simulation and experimental results have proved the efficiency of the methods.Imaging resolution is improved obviously and the embedded object in a test specimen is located accurately.
Two signal processing approaches are presented to improve imaging resolution in ultrasonic NDT of con- crete structures.When low-frequency B-scan data are processed by Synthetic Aperture Focusing Technique (SAFT), wavepacket will be further elongated because low-frequency detection signal covers a relative long period.Wavepacket Decomposition Technique (WDT) is introduced here to solve this problem.This method uses a few parameters to describe the original signal so that it can avoid the processing of the whole time history of signals.In practical mea- surement,ringing of commercial ultrasonic transducers also affects the discrimination of the detected signal,a method based on digital filtering is proposed to build the compensation model of transducer system.By eliminate the ringings with the filter,the spatiotemporal resolution of ultrasonic imaging is improved.Numerical simulation and experimental results have proved the efficiency of the methods.Imaging resolution is improved obviously and the embedded object in a test specimen is located accurately.
引文
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2孙宝申，张凡，沈建中．合成孔径聚焦声成像时域算法研究．声学学报，1997；22(1)：42—49
3刘纪元，唐劲松，孙宝申等．合成孔径声呐成像自聚焦方法研究．声学学报，2003；28(2)：151—154
4 Schickert M.Ultrasonic NDE of concrete.Proc.of 2002 IEEE Ultrasonics Symposium,Miinchen,2002,NY:Insti- tute of Electrical and Electronics Engineers (IEEE),2002: 718—727
5 Schmitz V,Chakhlov S,Miiller W.Experiences with syn- thetic aperture focusing technique in the field.Ultrasonics, 2000;38(8):739—744
6 Kroggel O,Schnapp J,Schickert M.Statistical evaluation of ultrasound images of concrete structures.British Insti- tute of Non-Destructive Testing,2002;45(12):853—859
7 Kazys R,Svilainis L.Analysis of adaptive imaging algo- rithms for ultrasonic non-destructive testing.Ultrasonics, 1995;33(1):19—30
8 Chaix J F,Garnier V,Corneloup G.Ultrasonic wave prop- agation in heterogeneous solid media:theoretical analy- sis and experimental validation.Ultrasonics,2006;44(2): 200—210
9 Delsanto P P,Hirsekorn S.A unified treatment of non- classical nonlinear effects in the propagation of ultrasound in heterogeneous media.Ultrasonics,2004;42(1):1005—1010
10 Mallat S,Zhang Z.Matching pursuit with time-frequency dictionaries.IEEE Trans.Signal Processing,1993;SP- 41:3397—3415
11 Shi L H,Chen B,Gao C.Design and modeling of signals by using wavelets for the pulse-echo NDT approaches.Proc. of 2001 SPIE-The International Society for Optical En- gineering,Newport Beach,CA,2001,Washington:SPIE, 2001:146—153
12石立华，徐其威，高成等．小波建模法在混凝土材料介电常数时域测量中的应用研究．解放军理工大学学报(自然科学版)，2002；3(6)：35—38
13 Demirli R,Saniie J.Model-based estimation of ultrasonic echoes part I:analysis and algorithms.IEEE Transac- tions on Ultrasonics,Ferroelectrics,and Frequency Con- trol,2001;48(3):787—802
14 Demirli R,Saniie J.Model-based estimation of ultra- sonic echoes partⅡ:nondestructive evaluation applica- tions.IEEE Transactions on Ultrasonics,Ferroelectrics, and Frequency Control,2001;48(3):803—811
15林书玉，桑永杰，田华．径向复合压电陶瓷超声换能器的径向振动特性研究。声学学报，2007；32f4)：310—315
16高天赋，曾娟，彭大勇．压电陶瓷换能器宽带匹配特性分析．声学学报，2007；32(2)：97—102
17孙海波，孔德仁，何瑛．传感器动态误差修正方法探讨．南京理工大学学报，2000；24f4)：330—333
18 Ljung L.System Identification:theory for the user.2nd. N J:Prentice-Hall,1999
19 Yoshikazu Ohara.Koichiro Kawashima.Detection of inter- hal micro defects by nonlinear resonant ultrasonic method using water immersion.Japanese Journal of Applied Physics,2004;43(5):3119—3120
20 Hak-joon Kiml,Sung-Jin Song,Schmerr L W.Modeling ultrasonic pulse-echo signals from a flat-bottom hole in im- mersion testing using a multi-Gaussian beam.Journal of Nondestructive Evaluation,2004;23(1):11—19
2孙宝申，张凡，沈建中．合成孔径聚焦声成像时域算法研究．声学学报，1997；22(1)：42—49
3刘纪元，唐劲松，孙宝申等．合成孔径声呐成像自聚焦方法研究．声学学报，2003；28(2)：151—154
4 Schickert M.Ultrasonic NDE of concrete.Proc.of 2002 IEEE Ultrasonics Symposium,Miinchen,2002,NY:Insti- tute of Electrical and Electronics Engineers (IEEE),2002: 718—727
5 Schmitz V,Chakhlov S,Miiller W.Experiences with syn- thetic aperture focusing technique in the field.Ultrasonics, 2000;38(8):739—744
6 Kroggel O,Schnapp J,Schickert M.Statistical evaluation of ultrasound images of concrete structures.British Insti- tute of Non-Destructive Testing,2002;45(12):853—859
7 Kazys R,Svilainis L.Analysis of adaptive imaging algo- rithms for ultrasonic non-destructive testing.Ultrasonics, 1995;33(1):19—30
8 Chaix J F,Garnier V,Corneloup G.Ultrasonic wave prop- agation in heterogeneous solid media:theoretical analy- sis and experimental validation.Ultrasonics,2006;44(2): 200—210
9 Delsanto P P,Hirsekorn S.A unified treatment of non- classical nonlinear effects in the propagation of ultrasound in heterogeneous media.Ultrasonics,2004;42(1):1005—1010
10 Mallat S,Zhang Z.Matching pursuit with time-frequency dictionaries.IEEE Trans.Signal Processing,1993;SP- 41:3397—3415
11 Shi L H,Chen B,Gao C.Design and modeling of signals by using wavelets for the pulse-echo NDT approaches.Proc. of 2001 SPIE-The International Society for Optical En- gineering,Newport Beach,CA,2001,Washington:SPIE, 2001:146—153
12石立华，徐其威，高成等．小波建模法在混凝土材料介电常数时域测量中的应用研究．解放军理工大学学报(自然科学版)，2002；3(6)：35—38
13 Demirli R,Saniie J.Model-based estimation of ultrasonic echoes part I:analysis and algorithms.IEEE Transac- tions on Ultrasonics,Ferroelectrics,and Frequency Con- trol,2001;48(3):787—802
14 Demirli R,Saniie J.Model-based estimation of ultra- sonic echoes partⅡ:nondestructive evaluation applica- tions.IEEE Transactions on Ultrasonics,Ferroelectrics, and Frequency Control,2001;48(3):803—811
15林书玉，桑永杰，田华．径向复合压电陶瓷超声换能器的径向振动特性研究。声学学报，2007；32f4)：310—315
16高天赋，曾娟，彭大勇．压电陶瓷换能器宽带匹配特性分析．声学学报，2007；32(2)：97—102
17孙海波，孔德仁，何瑛．传感器动态误差修正方法探讨．南京理工大学学报，2000；24f4)：330—333
18 Ljung L.System Identification:theory for the user.2nd. N J:Prentice-Hall,1999
19 Yoshikazu Ohara.Koichiro Kawashima.Detection of inter- hal micro defects by nonlinear resonant ultrasonic method using water immersion.Japanese Journal of Applied Physics,2004;43(5):3119—3120
20 Hak-joon Kiml,Sung-Jin Song,Schmerr L W.Modeling ultrasonic pulse-echo signals from a flat-bottom hole in im- mersion testing using a multi-Gaussian beam.Journal of Nondestructive Evaluation,2004;23(1):11—19
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