The photothermal wave field and high-resolution photothermal pulse compression thermography for ceramic/metal composite solids

2021 ◽  
pp. 115069
Author(s):  
Zhitao Luo ◽  
Hao Luo ◽  
Sheng Wang ◽  
Feilong Mao ◽  
Guodong Yin ◽  
...  
Keyword(s):  
High Resolution ◽  
Wave Field ◽  
Pulse Compression ◽  
Metal Composite

scholarly journals New broadband methods for resonance classification and high-resolution imagery of fish with swimbladders using a modified commercial broadband echosounder

2010 ◽  
Vol 67 (2) ◽  
pp. 365-378 ◽  
Author(s):  
Timothy K. Stanton ◽  
Dezhang Chu ◽  
J. Michael Jech ◽  
James D. Irish
Keyword(s):  
High Resolution ◽  
Pulse Compression ◽  
Target Strength ◽  
Compression Technique ◽  
Range Resolution ◽  
High Resolution Imagery ◽  
Broadband Signal ◽  
Scattering Strength ◽  
Broadband Signal Processing ◽  
Lower Frequencies

Abstract Stanton, T. K., Chu, D., Jech, J. M., and Irish, J. D. 2010. New broadband methods for resonance classification and high-resolution imagery of fish with swimbladders using a modified commercial broadband echosounder. – ICES Journal of Marine Science, 67: 365–378. A commercial acoustic system, originally designed for seafloor applications, has been adapted for studying fish with swimbladders. The towed system contains broadband acoustic channels collectively spanning the frequency range 1.7–100 kHz, with some gaps. Using a pulse-compression technique, the range resolution of the echoes is ∼20 and 3 cm in the lower and upper ranges of the frequencies, respectively, allowing high-resolution imaging of patches and resolving fish near the seafloor. Measuring the swimbladder resonance at the lower frequencies eliminates major ambiguities normally associated with the interpretation of fish echo data: (i) the resonance frequency can be used to estimate the volume of the swimbladder (inferring the size of fish), and (ii) signals at the lower frequencies do not depend strongly on the orientation of the fish. At-sea studies of Atlantic herring demonstrate the potential for routine measurements of fish size and density, with significant improvements in accuracy over traditional high-frequency narrowband echosounders. The system also detected patches of scatterers, presumably zooplankton, at the higher frequencies. New techniques for quantitative use of broadband systems are presented, including broadband calibration and relating target strength and volume-scattering strength to quantities associated with broadband signal processing.

scholarly journals A Crack Size Quantification Method Using High-Resolution Lamb Waves

Sensors ◽  
2021 ◽  
Vol 21 (20) ◽  
pp. 6941
Author(s):  
Xianjun Li ◽  
Jinsong Yang ◽  
Guangdong Zhang
Keyword(s):  
Signal Processing ◽  
High Resolution ◽  
Pulse Compression ◽  
Lamb Waves ◽  
Tone Burst ◽  
Crack Size ◽  
Time Duration ◽  
Quantification Method ◽  
Wave Package ◽  
Signal Processing Methods

Traditional tone burst excitation cannot attain a high output resolution, due to the time duration. The received signal is much longer than that of excitation during the propagation, which can increase the difficulty of signal processing, and reduce the resolution. Therefore, it is of significant interest to develop a general methodology for crack quantification through the optimal design of the excitation waveform and signal-processing methods. This paper presents a new crack size quantification method based on high-resolution Lamb waves. The linear chirp (L-Chirp) signal and Golay complementary code (GCC) signal are used as Lamb wave excitation signals. After dispersion removal, these excitation waveforms, based on pulse compression, can effectively improve the inspection resolution in plate-like structures. A series of simulations of both healthy plates and plates with different crack sizes are performed by Abaqus CAE, using different excitation waveforms. The first wave package of the S0 mode after pulse compression is chosen to extract the damage features. A multivariate regression model is proposed to correlate the damage features to the crack size. The effectiveness of the proposed crack size quantification method is verified by a comparison with tone burst excitation, and the accuracy of the crack size quantification method is verified by validation experiments.

High Resolution Ultrasonic Distance Measurement Systems Using Pulse Compression and Their Applications

2005 ◽  
Vol 295-296 ◽  
pp. 301-306 ◽  
Author(s):  
Herbert F. Schweinzer ◽  
H. Elmer
Keyword(s):  
High Resolution ◽  
Pulse Compression ◽  
Noise Suppression ◽  
Low Cost ◽  
Distance Measurement ◽  
Measurement Systems ◽  
High Measurement ◽  
New Applications ◽  
Measurement Rate ◽  
Small Resolution

Ultrasonic distance measurement in air is broadly used for industrial and commercial low cost applications with medium or small resolution. Configurations for the applications are usually restricted to passive reflection and A-B measurement. This paper gives a survey of the ultrasonic distance measurement method with high resolution based on pulse compression. Improvements resulting from this method include good noise suppression, possibility to operate several systems in parallel without disturbing influence of cross talk, and high measurement rate. Modified configurations and the available high resolution lead to new applications which are summarized.

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