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

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.

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.

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

INFLUENCE OF MAGNETIC NANOPARTICLES ON ACOUSTIC ATTENUATION IN LIQUIDS

Akustika ◽  
2020 ◽  
pp. 8-13
Author(s):  
Štefan Hardoň ◽  
Jozef Kúdelčík
Keyword(s):  
Magnetic Nanoparticles ◽  
Heat Exchangers ◽  
Magnetic Fluids ◽  
Magnetic Flux Density ◽  
Acoustic Attenuation ◽  
Cooling Systems ◽  
Practical Applications ◽  
Acoustic Spectroscopy ◽  
Aggregation Processes ◽  
Diagnostics And Therapy

Magnetic fluids with nanoparticles dispersed in water or oils offer attractive applications in biomedicine and industry. Biocompatible magnetic fluids are used for diagnostics and therapy in medical applications, in pharmacy, and biosensors. Application of ferrofluids is expanding into energy conservation, faster and efficient cooling, and hence better performance in a wide variety of practical applications (in heat exchangers, mainly in micro-cooling systems). For the study of the influence of an external magnetic field on the aggregation processes of magnetic nanoparticles in magnetic fluids, acoustic spectroscopy was used. The jump changes of the magnetic flux density at various temperatures influenced the acoustic attenuation. The measured changes were results of nanoparticle aggregations into new structures.

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