Skull's acoustic attenuation and dispersion modeling on photoacoustic signal

2018 ◽  
Author(s):  
Leila Mohammadi ◽  
Hamid Behnam ◽  
Jahan Tavakkoli ◽  
Mohammadreza Nasiriavanaki
Keyword(s):  
Photoacoustic Signal ◽  
Dispersion Modeling ◽  
Acoustic Attenuation ◽  
Attenuation And Dispersion

scholarly journals Skull’s Photoacoustic Attenuation and Dispersion Modeling with Deterministic Ray-Tracing: Towards Real-Time Aberration Correction

Sensors ◽  
2019 ◽  
Vol 19 (2) ◽  
pp. 345 ◽  
Author(s):  
Leila Mohammadi ◽  
Hamid Behnam ◽  
Jahan Tavakkoli ◽  
Mohammad Avanaki
Keyword(s):  
Ray Tracing ◽  
Mode Conversion ◽  
Ex Vivo ◽  
Photoacoustic Imaging ◽  
Time Shift ◽  
Dispersion Modeling ◽  
Transmission Coefficients ◽  
Time Domain Signal ◽  
Wave Transmission Coefficients ◽  
Attenuation And Dispersion

Although transcranial photoacoustic imaging has been previously investigated by several groups, there are many unknowns about the distorting effects of the skull due to the impedance mismatch between the skull and underlying layers. The current computational methods based on finite-element modeling are slow, especially in the cases where fine grids are defined for a large 3-D volume. We develop a very fast modeling/simulation framework based on deterministic ray-tracing. The framework considers a multilayer model of the medium, taking into account the frequency-dependent attenuation and dispersion effects that occur in wave reflection, refraction, and mode conversion at the skull surface. The speed of the proposed framework is evaluated. We validate the accuracy of the framework using numerical phantoms and compare its results to k-Wave simulation results. Analytical validation is also performed based on the longitudinal and shear wave transmission coefficients. We then simulated, using our method, the major skull-distorting effects including amplitude attenuation, time-domain signal broadening, and time shift, and confirmed the findings by comparing them to several ex vivo experimental results. It is expected that the proposed method speeds up modeling and quantification of skull tissue and allows the development of transcranial photoacoustic brain imaging.

Dissipative attenuation and dispersion modeling with application in Campos basin

1987 ◽  
Author(s):  
Carlos Lopo Varela ◽  
Vandemir Ferreira de Oliveira ◽  
Eduardo Lopes de Faria
Keyword(s):  
Dispersion Modeling ◽  
Campos Basin ◽  
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.

Modeling of attenuation and dispersion

Geophysics ◽  
1993 ◽  
Vol 58 (8) ◽  
pp. 1167-1173 ◽  
Author(s):  
Carlos Lopo Varela ◽  
Andre L. R. Rosa ◽  
Tadeusz J. Ulrych
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Low Cost ◽  
Real Data ◽  
Dispersion Modeling ◽  
Minimum Phase ◽  
The Time Domain ◽  
Wavefield Extrapolation ◽  
Attenuation And Dispersion ◽  
Proper Solutions

At the present time, proper solutions for absorption modeling are based on wavefield extrapolation techniques which, in some instances, may be considered expensive. Two alternative, low cost, but incomplete solutions exist in the literature. The first models dispersion in the frequency domain in accordance with the Futterman dispersive relations but does not consider attenuation. The second models both attenuation and dispersion in the time domain but assumes a digital minimum‐phase formulation that results in an inadequate treatment of the dispersion. We show that this second solution can be adapted to perform attenuation and/or dispersion modeling in agreement with the Futterman attenuation‐dispersion relationships thus obviating the shortcoming mentioned above. Synthetic and real data examples are shown to illustrate the performance of the proposed algorithm.

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