Resolution enhancement of ultrasonic echo signals for nondestructive evaluation

本项目的最终目标是开发一种稳定的超声回波分离算法，以提高超声扫描的定时分辨率。目标应用领域是使用一种称为“飞行时间衍射”的几何技术来评估管道焊缝中的裂纹深度。传统的提高时间分辨率的技术大多基于一种称为反褶积的信号处理反演技术，然而，在实际应用中，使用固定参考波形的反褶积常常失败，因为实际应用中返回波形已经被衰减、色散和缺陷几何变化所修改。因此，我们提出了一种能够使用自适应参考波形的新算法。换能器建模将为我们的回波分离算法提供物理基础。该算法将在合成超声扫描和实际超声扫描中进行测试，以评估其有效性。我们将评估所提出的算法与合成孔径聚焦技术相结合以提高二维超声扫描的时间和横向分辨率的可行性。

The ultimate goal of this project is to develop a stable ultrasonic echo separation algorithm to improve thetiming resolution of ultrasonic scans. The targeted area of application is assessment of crack depths in pipelinegirth welds using a geometric technique called "time-of-flight diffraction. Conventional techniques to improvetemporal resolution are mostly based on on a signal processing inversion technique called deconvolution.However, deconvolution using a fixed reference waveform often fails in actual applications where the returnwaveforms have been modified by attenuation, dispersion and variations in defect geometry. Consequently, wepropose a new algorithm that enables the use of adaptive reference waveforms.Transducer modeling will be used to give a physical basis for our echo separation algorithm. The algorithmwill be tested on both synthetic and actual ultrasonic scans to assess its effectiveness. We will evaluate thefeasibility of combining the proposed algorithm with the Synthetic Aperture Focusing Technique to improveboth temporal and lateral resolution in 2D ultrasonic scans.