Modeling skull's acoustic attenuation and dispersion on photoacoustic signal

2017 ◽  
Author(s):  
L. Mohammadi ◽  
H. Behnam ◽  
M. R. Nasiriavanaki
Keyword(s):  
Photoacoustic Signal ◽  
Acoustic Attenuation ◽  
Attenuation And Dispersion

An Improved Phased Array Ultrasonic Testing Technique for Thick-Wall Polyethylene Pipe Used in Nuclear Power Plant

2018 ◽  
Author(s):  
Yinkang Qin ◽  
Jianfeng Shi ◽  
Jinyang Zheng
Keyword(s):  
Numerical Simulation ◽  
Ultrasonic Testing ◽  
Nuclear Power ◽  
Phased Array ◽  
Propagation Distance ◽  
Ultrasonic Field ◽  
Thick Wall ◽  
Acoustic Attenuation ◽  
Waveform Distortion ◽  
Attenuation And Dispersion

With the application of High-density polyethylene (HDPE) pipe with thick wall in nuclear power plant (NPP), great attention has been paid to the safety of the pipeline’s joints, which can be assessed by phased array ultrasonic testing (PAUT). PAUT creates constructive interference of acoustic waves to generate focused beams according to delay law based on time-of-flight. However, due to the existence of acoustic attenuation and dispersion, waveform distortion occurs when ultrasonic pulse propagates in HDPE, which will accumulate with the increase of propagation distance, and then results in imaging errors. In this paper, the relationship of acoustic attenuation and dispersion in HDPE was obtained by numerical simulation in Field II®, which can be verified by the experiment of our previous work. Besides, the investigation of the waveform distortion revealed the linear relation between peak offset and propagation distance. Considering the relation, an improved delay law was proposed to increase the intensity of ultrasonic field. This improved delay law was compared with the conventional one by numerical simulation of ultrasonic field and PAUT experiments, which showed that the improved delay law could increase the image sensitivity.

Order‐disorder phenomena. VIII. Acoustic attenuation and dispersion in NH4Cl

1973 ◽  
Vol 58 (11) ◽  
pp. 5002-5008 ◽  
Author(s):  
Carl W. Garland ◽  
Richard J. Pollina
Keyword(s):  
Acoustic Attenuation ◽  
Attenuation And Dispersion

Investigation on Acoustic Propagation of Ultrasound in Polyethylene Pipe Used in Nuclear Power Plant

2017 ◽  
Author(s):  
Xiong Sheng ◽  
Dongsheng Hou ◽  
Jinyang Zheng
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Phase Velocity ◽  
Attenuation Coefficient ◽  
Nuclear Power ◽  
Image Resolution ◽  
Energy Concentration ◽  
Acoustic Attenuation ◽  
Hdpe Pipe ◽  
Attenuation And Dispersion

Polyethylene (PE) pipe, particularly high-density polyethylene (HDPE) pipe, has been successfully utilized to transport cooling water for both non-safety-related applications and safety-related applications in nuclear power plant (NPP). However, concerns of a lack of non-destructive examination (NDE) procedures and qualifications specialized for HDPE pipe impede its broader application. Traditional approximation without considering effects of acoustic dispersion could work for PE pipe with a small inspection depth. But for PE pipe of large size used in nuclear power plant, effects of acoustic attenuation and dispersion accumulate with depth, and have influence on waveforms of target pules, which brings great challenges to the energy concentration when performing ultrasonic phased-array inspection for PE pipe in NPP. In this paper, a theoretical method applying Szabo’s causal convolutional propagation operator based on causality theory was presented to obtain wave equations of ultrasound in PE considering both attenuation and dispersion, in which attenuation coefficient and phase velocity were used to separately characterize acoustic attenuation and dispersion. Then, an experimental method using ultrasonic spectroscopy technology was proposed to confirm the proposed model, and a good agreement was obtained. The results indicated that attenuation coefficient of PE had an approximately linear relation with frequency and that phase velocity rose logarithmically with frequency. Finally, effects of attenuation and dispersion on amplitude spectrum and waveform in time domain of the target signal were investigated. Frequency downshift and time delay shift had an influence on image resolution and focus capability, and were believed to be a restriction of current inspection technology. This work also theoretically proved that lower testing frequencies (less than 2.5MHz) could improve the inspection effectiveness of the applied inspecting systems for HDPE pipes in NPP applications.

scholarly journals Resolution Limits in Photoacoustic Imaging Caused by Acoustic Attenuation

2019 ◽  
Vol 5 (1) ◽  
pp. 13 ◽  
Author(s):  
Peter Burgholzer ◽  
Johannes Bauer-Marschallinger ◽  
Bernhard Reitinger ◽  
Thomas Berer
Keyword(s):  
Acoustic Waves ◽  
Photoacoustic Imaging ◽  
Signal To Noise Ratio ◽  
Finite Size ◽  
Photoacoustic Signal ◽  
Dissipated Energy ◽  
Reconstruction Method ◽  
Square Root ◽  
Resolution Limit ◽  
Acoustic Attenuation

In conventional photoacoustic tomography, several effects contribute to the loss of resolution, such as the limited bandwidth and the finite size of the transducer, or the space-dependent speed of sound. They can all be compensated (in principle) technically or numerically. Frequency-dependent acoustic attenuation also limits spatial resolution by reducing the bandwidth of the photoacoustic signal, which can be numerically compensated only up to a theoretical limit given by thermodynamics. The entropy production, which is the dissipated energy of the acoustic wave divided by the temperature, turns out to be equal to the information loss, which cannot be compensated for by any reconstruction method. This is demonstrated for the propagation of planar acoustic waves in water, which are induced by short laser pulses and measured by piezoelectric acoustical transducers. It turns out that for water, where the acoustic attenuation is proportional to the squared frequency, the resolution limit is proportional to the square root of the distance and inversely proportional to the square root of the logarithm of the signal-to-noise ratio. The proposed method could be used in future work for media other than water, such as biological tissue, where acoustic attenuation has a different power-law frequency dependence.

An Improved Phased Array Ultrasonic Testing Technique for Thick-Wall Polyethylene Pipe Used in Nuclear Power Plant

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Yinkang Qin ◽  
Jianfeng Shi ◽  
Jinyang Zheng ◽  
Dongsheng Hou ◽  
Weican Guo
Keyword(s):  
Numerical Simulation ◽  
Ultrasonic Testing ◽  
Nuclear Power ◽  
Phased Array ◽  
Propagation Distance ◽  
Ultrasonic Field ◽  
Thick Wall ◽  
Acoustic Attenuation ◽  
Waveform Distortion ◽  
Attenuation And Dispersion

With the application of high-density polyethylene (HDPE) pipe with thick wall in nuclear power plant (NPP), great attention has been paid to the safety of the pipeline joints, which can be assessed by phased array ultrasonic testing (PAUT). PAUT creates constructive interference of acoustic waves to generate focused beams according to delay law based on time-of-flight. However, due to the existence of acoustic attenuation and dispersion, waveform distortion occurs when ultrasonic pulse propagates in HDPE, which will accumulate with the increase of propagation distance, and then results in imaging errors. In this paper, the relationship between acoustic attenuation and dispersion in HDPE was obtained by numerical simulation in Field II®, which can be verified by the experiment of our previous work. Then, the investigation of the waveform distortion revealed the linear relation between peak offset and propagation distance. Considering the relation, an improved delay law was proposed to increase the intensity of ultrasonic field. This improved delay law was compared with the conventional one by numerical simulation of ultrasonic field and PAUT experiments, which showed that the improved delay law could increase the image sensitivity.

COATING FOR AN UNDERWATER ACTIVE ACOUSTIC ATTENUATION CONTROL SYSTEM

1990 ◽  
Vol 51 (C2) ◽  
pp. C2-801-C2-804
Author(s):  
T. R. HOWARTH ◽  
X.-Q. BAO ◽  
V. K. VARADAN ◽  
V. V. VARADAN
Keyword(s):  
Control System ◽  
Acoustic Attenuation
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