Analysis of Acoustic Wave Due to Gas Leakage in Buried Gas Pipe

2009 ◽  
Author(s):  
Eui Youl Kim ◽  
Min Soo Kim ◽  
Sang Kwon Lee
Keyword(s):  
Wave Propagation ◽  
Acoustic Wave ◽  
Low Frequency ◽  
Acoustic Signals ◽  
Frequency Method ◽  
Theoretical Formulation ◽  
Steel Pipes ◽  
Time Frequency ◽  
Gas Leakage ◽  
Made In

A time frequency technique for locating leaks in buried gas distribution pipes involves the use of the cross-correlation on two measured acoustic signals on either side of a leak. This technique can be problematic for locating leaks in steel pipes, as the acoustic signals in these pipes are generally narrowband and low frequency. The effectiveness of the time-frequency technique for detecting leaks in steel pipes was investigated experimentally in an earlier study. The object of this paper is to identify the characteristics of this dispersive acoustic wave through analysis of the cut-off frequency by using the time-frequency method experimentally and BEM (boundary element method) theoretically for the development of an experimental tool to analyze the leak signals in steel pipe. The tool is based on experimental work and theoretical formulation of wave propagation in a fluid-filled pipe. This tool uses the time-frequency method to explain some of the features of wave propagation measurements made in gas pipes. Leak noise signals are generally passed through a time-frequency filter for detection of impulse signal related leakage.

IDENTIFICATION OF IMPACT FORCE ON THE GAS PIPE BASED ON ANALYSIS OF THE ACOUSTIC WAVE

2008 ◽  
Vol 22 (09n11) ◽  
pp. 1039-1044 ◽  
Author(s):  
MIN-SOO KIM ◽  
SANG-KWON LEE ◽  
SUNG-JONG KIM
Keyword(s):  
Acoustic Wave ◽  
Cavity Mode ◽  
Impact Force ◽  
Correlation Technique ◽  
Frequency Method ◽  
Time Frequency ◽  
Long Time ◽  
Mode Characteristics ◽  
The Impact ◽  
The Waves

An acoustic wave signal measured on the gas pipe due to impact force is transfer to the far distance through the medium inside of duct. This signal is very complex since it includes the acoustic wave and solid wave. Acoustic wave is affected by the cavity mode inside of duct. The analysis of this acoustic wave gives information about the impact force. For the analysis of this signal, the correlation technique has been used for a long time. This method has a limitation for the application since the waves have dispersive and cavity mode characteristics for the flexible wave. In this paper, we present the time-frequency method for the identification of impact force and the location of impact on the gas pipe. The results give the useful information for the impact force and are applied to the analysis of leakage location of the gas pipe.

scholarly journals ANOMALOUS SEISMO-ACOUSTIC WAVE PROPAGATION AND DETERMINATION SOURCE OF INFRASOUND

2017 ◽  
pp. 29-35
Author(s):  
Bayarsaikhan Ch ◽  
Tungalag L ◽  
Lkhagvajav Ch ◽  
Alexis Le Pichon
Keyword(s):  
Wave Propagation ◽  
Acoustic Wave ◽  
Frequency Analysis ◽  
Acoustic Signals ◽  
General Analysis ◽  
Acoustic Wave Propagation ◽  
Speed Distribution ◽  
Wide Range ◽  
Seasonal Wind

The network of infrasound stations (I34MN) in Mongolia daily registers set of infrasound from various sources besides explosions. The data from explosions in mines in region and from other sources detected since 2000 to 2009 in seismic and infrasound stations is analyzed. The analysis these signals dependence of speed distribution of sound from seasonal, wind forces and direction moreover on short distances. From detected in infrasound stations (I34MN) in year 80-90 % of signals make microbaroms, the wide range of their sources is visible from the frequency analysis. From the general analysis registered seismo and acoustic signals of explosions on the seismic and infrasound networks stations miscalculate not only speeds of distribution of sounds on close distances (50-500 km),  and also the speed model of atmosphere is made.

scholarly journals Ultrasound shear wave elastography: numerical modeling and time-frequency analysis with an application in HIFU thermal lesion detection

2021 ◽  
Author(s):  
Pooya Sobhe Bidari
Keyword(s):  
Wave Propagation ◽  
Acoustic Wave ◽  
Shear Wave ◽  
Frequency Analysis ◽  
Acoustic Wave Propagation ◽  
Thermal Lesion ◽  
Time Frequency Analysis ◽  
Time Frequency ◽  
Thermal Lesions ◽  
Viscoelastic Parameters

In this work, a new numerical framework is proposed and implemented to simulate acoustic wave propagation in 3D viscoelastic heterogeneous media. The framework is based on the elastodynamic wave equation in which a 3D second-order time-domain perfectly matched layer (PML) formulation is developed to model unbounded media. The numerical framework is discretized by a finite difference formulation and its stability analysis is discussed. The proposed numerical method is capable of simulating 3D shear and longitudinal acoustic waves for arbitrary source geometries and excitations, together with arbitrary initial and boundary conditions. After validation of the framework, it was used to simulate the propagation of ultrasound shear wave in high intensity focused ultrasound (HIFU) induced thermal lesions located within soft tissue. The parameters in these simulations were obtained from standard double-indentation measurements of the viscoelastic parameters of normal and thermally coagulated chicken breast tissue samples. A HIFU system was used to induce thermal lesions in tissue. In this study, a new elastography procedure was also introduced to differentiate between the normal and HIFU induced thermal lesions. This method is based on time-frequency analysis of shear wave propagation within the tissue. In the proposed method, the Wigner-Ville distribution has been used as a time-frequency analytical technique to detect the location of shear wave propagating within the tissue, and to estimate the shear speed of the wave as well as its center frequency and attenuation coefficient. This method was applied to the acoustic wave propagation simulation results of the HIFU thermal lesion. It was finally used to estimate the local viscoelastic parameters of the medium. It was demonstrated that the proposed method is capable of differentiating the thermal lesions from the normal tissue based on their viscoelastic parameters.

scholarly journals Identification of ship wake structures by a time–frequency method

2015 ◽  
Vol 765 ◽  
pp. 229-251 ◽  
Author(s):  
T. Torsvik ◽  
T. Soomere ◽  
I. Didenkulova ◽  
A. Sheremet
Keyword(s):  
High Frequency ◽  
Individual Component ◽  
Energy Content ◽  
Low Frequency ◽  
Frequency Method ◽  
Ship Wake ◽  
Time Frequency ◽  
Time Space ◽  
Short Time ◽  
Ship Speed

AbstractThe wake of a ship that sails at relatively large Froude numbers usually contains a number of components of different nature and with different heights, lengths, timings and propagation directions. We explore the possibilities of the spectrogram representation of one-point measurements of the ship wake to identify these components and to quantify their main properties. This representation, based on the short-time Fourier transform, facilitates a reliable decomposition of the wake into constituent components and makes it possible to quantify their variations in the time–space domain and the energy content of each component, from very low-frequency precursor waves up to high-frequency signals within the frequency range of typical wind-generated waves. A method for estimation of the ship speed and the distance of its sailing line from the measurement site is proposed, which only uses information available within the record of the ship wake surface elevation, but where it is assumed that the wake pattern does not deviate significantly from the classical Kelvin wake structure. The wake decomposition using the spectrogram method allows investigation of the energy content that can be attributed to each individual component of the wake. We demonstrate that the majority (60–80 %) of wake energy from strongly powered large ferries that sail at depth Froude numbers ${\sim}0.7$ is concentrated in components that are located near the edge of the wake wedge. Finally, we demonstrate that the spectrogram representation offers a convenient way to identify a specific signature of single types of ships.

Modelling of low-frequency acoustic wave propagation in dilute gas-bubbly liquids

2021 ◽  
pp. 106979
Author(s):  
Zizhen Wang ◽  
Weidong Zhou ◽  
Tengfei Shu ◽  
Qilong Xue ◽  
Rui Zhang ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Acoustic Wave ◽  
Low Frequency ◽  
Acoustic Wave Propagation ◽  
Bubbly Liquids ◽  
Dilute Gas
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