12 results on '"Source location"'
Search Results
2. A New Acoustic Emission Source Location Method Using Tri-Variate Kernel Density Estimator
- Author
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Zilong Zhou, Riyan Lan, Yichao Rui, Jing Zhou, Longjun Dong, Ruishan Cheng, and Xin Cai
- Subjects
Acoustic emission (AE) ,distribution model ,Kernel density estimator ,outlier ,source location ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 - Abstract
A new AE location method using tri-variate kernel density estimator is developed in this paper. Firstly, combinations of every six arrivals are obtained from a multi-sensor location system, and the preliminary location results are obtained by solving the systems of linear equations constructed by these arrival combinations. Secondly, the tri-variate scaled kernel functions at each AE source coordinate are established. The tri-variate kernel density estimator is constructed by adding and normalizing these scaled kernel functions. Finally, the extreme value of the density function is calculated and the coordinate corresponding to the extreme value is extracted as the final location result. Pencil-lead break experiments were carried out. The results verified that the proposed method was more accurate and effective than traditional methods in the location performance. Moreover, the influence of outlier scales and proportions of the proposed method were investigated by simulation tests. Results showed that the location performance of the proposed method was higher than that of traditional methods under different outlier scales and proportions.
- Published
- 2019
- Full Text
- View/download PDF
3. Acoustic emission characteristics of a fine-grained marble with different thermal damages and specimen sizes.
- Author
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Peng, Jun, Rong, Guan, Yao, Mengdi, Wong, Louis Ngai Yuen, and Tang, Zhicheng
- Subjects
- *
ACOUSTIC emission , *MARBLE , *ROCK deformation , *FAILURE mode & effects analysis , *TIME pressure - Abstract
Acoustic emission (AE) is a technique which has been widely used in geomechanics to study the progressive micro-cracking behavior of rocks in response to different loadings. However, the study of the combined effects of thermal damage and specimen size on the performance of rocks using the AE technique is still limited, which needs further investigation. This study experimentally investigated the AE characteristics of a fine-grained marble with different thermal damages and specimen sizes. The variation of AE counts in response to the rock deformation can divide the stress−strain relation into several stages. The AE activity is limited in the initial deformation stage and multiplies at a stress level about 0.7 to 0.8 times the peak stress. However, the AE signals in the initial stage become more prominent as the treatment temperature increases. The accumulated AE parameters (i.e., AE counts, AE hits, and AE energy) are found to decrease with the increase in the treatment temperature. The b-value, which generally decreases as the stress approaches the peak strength, correlates well with the stress−strain relation. It is also found that the b-value generally increases as the treatment temperature gradually increases, which is mainly attributed to the initially generated thermal micro-cracks in the rock specimen. The real-time spatial distribution of AE events is in considerable agreement with the failure mode observed in laboratory tests. Overall, the results in this study reveal that the AE technique is capable of studying the micro-cracking behavior involved in the deformation process of rocks possessing different degrees of thermal damage and with different specimen sizes. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
4. A Closed-Form Method of Acoustic Emission Source Location for Velocity-Free System Using Complete TDOA Measurements
- Author
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Zilong Zhou, Yichao Rui, Xin Cai, Riyan Lan, and Ruishan Cheng
- Subjects
acoustic emission (AE) ,source location ,time difference of arrival (TDOA) ,velocity-free ,Chemical technology ,TP1-1185 - Abstract
A closed-form method of acoustic emission (AE) source location for a velocity-free system using complete time difference of arrival (TDOA) measurements is proposed in this paper. First, this method established the governing equation of unknown acoustic velocity for each sensor; then, the governing equations of each of the three sensors were transformed into a linear equation, which can form a system of linear equations with the complete TDOA measurements. Third, the least squares solutions of the AE source coordinate and acoustic velocity were separately solved by an orthogonal projection operator. The proposed method was verified by the pencil-lead break experiment, and the results showed that the location accuracy and stability of the proposed method were better than those of traditional methods. Moreover, a simulation test was carried out to investigate the influence of noise scales on the location accuracy, and the results further prove that the proposed method holds higher noise immunity than the traditional methods.
- Published
- 2020
- Full Text
- View/download PDF
5. Guided wave mode dispersion of transient acoustic emission on copper pipes—Its visualisation and application to source location.
- Author
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Wang, Chao, Joe Au, Y.H., Li, Lin, and Cheng, Kai
- Subjects
- *
ELASTIC waves , *DISPERSION (Chemistry) , *COPPER pipe , *ACOUSTIC emission , *FOURIER transforms , *VISUALIZATION - Abstract
In this paper is presented an improved method for locating a transient acoustic emission (AE) source on a pipeline with two broad-band AE sensors. Using Short Time Fourier Transform (STFT), the method identifies a flexural wave mode, F (1,1), in the two AE signals detected, notes its respective arrival times at different frequencies, and determines the location of the AE source based on the arrival times. Due to velocity dispersion, the arrival time of the wave mode varies with frequency. The method has three main advantages: that the wave speed is not required in the calculation, that it is insensitive to threshold setting for arrival time estimation, and that, at least in theory, the accuracy of the source location can be made as high as desired. The paper first demonstrates, by way of an experiment, the inadequacy of threshold-crossing as a method for identifying the first arrival time of the AE wave. The paper then presents the theory of the proposed method and of the estimated error inherent in the theory and an explanation on how the error can be reduced. The method is then verified experimentally using results obtained from a 3-m long copper pipe of 22 mm diameter. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
6. A New Acoustic Emission Source Location Method Using Tri-Variate Kernel Density Estimator
- Author
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Longjun Dong, Xin Cai, Ruishan Cheng, Riyan Lan, Yichao Rui, Jing Zhou, and Zilong Zhou
- Subjects
distribution model ,source location ,General Computer Science ,Kernel density estimation ,Probability density function ,02 engineering and technology ,010502 geochemistry & geophysics ,System of linear equations ,01 natural sciences ,General Materials Science ,Extreme value theory ,Acoustic emission (AE) ,0105 earth and related environmental sciences ,Mathematics ,General Engineering ,021001 nanoscience & nanotechnology ,outlier ,Random variate ,Acoustic emission ,Kernel (statistics) ,Outlier ,lcsh:Electrical engineering. Electronics. Nuclear engineering ,0210 nano-technology ,lcsh:TK1-9971 ,Algorithm ,Kernel density estimator - Abstract
A new AE location method using tri-variate kernel density estimator is developed in this paper. Firstly, combinations of every six arrivals are obtained from a multi-sensor location system, and the preliminary location results are obtained by solving the systems of linear equations constructed by these arrival combinations. Secondly, the tri-variate scaled kernel functions at each AE source coordinate are established. The tri-variate kernel density estimator is constructed by adding and normalizing these scaled kernel functions. Finally, the extreme value of the density function is calculated and the coordinate corresponding to the extreme value is extracted as the final location result. Pencil-lead break experiments were carried out. The results verified that the proposed method was more accurate and effective than traditional methods in the location performance. Moreover, the influence of outlier scales and proportions of the proposed method were investigated by simulation tests. Results showed that the location performance of the proposed method was higher than that of traditional methods under different outlier scales and proportions.
- Published
- 2019
7. A Closed-Form Method of Acoustic Emission Source Location for Velocity-Free System Using Complete TDOA Measurements
- Author
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Xin Cai, Riyan Lan, Yichao Rui, Zilong Zhou, and Ruishan Cheng
- Subjects
source location ,Letter ,02 engineering and technology ,System of linear equations ,lcsh:Chemical technology ,Biochemistry ,Least squares ,Analytical Chemistry ,0202 electrical engineering, electronic engineering, information engineering ,lcsh:TP1-1185 ,Particle velocity ,Electrical and Electronic Engineering ,Instrumentation ,Mathematics ,time difference of arrival (TDOA) ,velocity-free ,Orthographic projection ,Mathematical analysis ,020206 networking & telecommunications ,021001 nanoscience & nanotechnology ,Multilateration ,Atomic and Molecular Physics, and Optics ,Noise ,acoustic emission (AE) ,Acoustic emission ,0210 nano-technology ,Linear equation - Abstract
A closed-form method of acoustic emission (AE) source location for a velocity-free system using complete time difference of arrival (TDOA) measurements is proposed in this paper. First, this method established the governing equation of unknown acoustic velocity for each sensor; then, the governing equations of each of the three sensors were transformed into a linear equation, which can form a system of linear equations with the complete TDOA measurements. Third, the least squares solutions of the AE source coordinate and acoustic velocity were separately solved by an orthogonal projection operator. The proposed method was verified by the pencil-lead break experiment, and the results showed that the location accuracy and stability of the proposed method were better than those of traditional methods. Moreover, a simulation test was carried out to investigate the influence of noise scales on the location accuracy, and the results further prove that the proposed method holds higher noise immunity than the traditional methods.
- Published
- 2020
8. Acoustic emission source location on large plate-like structures using a local triangular sensor array
- Author
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Aljets, Dirk, Chong, Alex, Wilcox, Steve, and Holford, Karen
- Subjects
- *
ACOUSTIC emission , *STRUCTURAL plates , *STRUCTURAL analysis (Engineering) , *STRUCTURAL health monitoring , *NONDESTRUCTIVE testing , *DETECTORS , *ALGORITHMS , *CALIBRATION - Abstract
Abstract: A new acoustic emission (AE) source location method was developed for large plate-like structures, which evaluates the location of the source using a combined time of flight and modal source location algorithm. Three sensors are installed in a triangular array with a sensor to sensor distance of just a few centimeters. The direction from the sensor array to the AE source can be established by analysing the arrival times of the A 0 component of the signal to the three sensors whilst the distance can be evaluated using the separation of S0 and A0 mode at each sensor respectively. The close positioning of the sensors allows the array to be installed in a single housing. This simplifies mounting, wiring and calibration procedures for non-destructive testing (NDT) and structural health monitoring (SHM) applications. Furthermore, this array could reduce the number of sensors needed to monitor large structures compared to other methods. An automatic wave mode identification method is also presented. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
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9. Acoustic emission source location from P-wave arrival time corrected data and virtual field optimization method.
- Author
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Shang, Xueyi, Wang, Yi, and Miao, Runxue
- Subjects
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ACOUSTIC emission , *ACOUSTIC radiators , *SIGNAL sampling , *CONSTRUCTION cost estimates , *FAILURE mode & effects analysis , *DATA compression , *DATABASES - Abstract
• P-wave arrival time system error (PATSE) was observed during pencil-lead break tests. • A Bayesian framework using MCMC sampling was established to estimate the PATSE. • The improved VFOM has a better location result than the L1 and L2 norm based methods. • The PATSE corrected data based method has a good location accuracy. Acoustic emission (AE) event location plays an important role in structural safety assessments. However, accurately locating an AE event is usually difficult, especially for a small structure. Interestingly, a pencil-lead break (PLB) experiment shows that the P-wave arrival time of a sensor is always significantly different (~260 µs) from that of the other sensors. This time difference is much greater than the P-wave travel time in the range of the experimental sample. Therefore, it can be inferred that there is a P-wave arrival time system error (PATSE) for each sensor. The PATSE may be due to a combined result of the sensor site effect and signal transfer delay time from the sensor to the signal storage. To handle this, a Bayesian inversion framework was built to estimate PATSEs. A synthetic test demonstrated the effectiveness of the proposed Bayesian method for noisy P-wave arrival time data. Then, Bayesian inversion was applied to 15 PLB events, which confirmed the existence of PATSE in an AE experiment for the first time. The average PATSE reached 1.47 µs without considering the P-wave arrival time significantly different sensor. The average location error of 25 PLB events was 14.30 mm and 6.58 mm for PATSE unremoved and removed data, respectively. To achieve this, a high-precision virtual field optimization location method (VFOM) was used. This demonstrates the necessity of removing the PATSEs. Finally, the AE event location performance for the PATSE unremoved and removed data was compared, where the AE events were obtained from the uniaxial compression of a red sandstone sample. The results indicated that there was a higher location detection success rate for the corrected data. The AE locations based on the corrected data were in a better correlation with the rock sample failure mode than that without correction. Moreover, increase the signal sampling frequency for AE event identification, use a real-time inverted 3D velocity model and update the PATSEs in real time could be used to further improve the AE event location accuracy. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
10. A Closed-Form Method of Acoustic Emission Source Location for Velocity-Free System Using Complete TDOA Measurements.
- Author
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Zhou, Zilong, Rui, Yichao, Cai, Xin, Lan, Riyan, and Cheng, Ruishan
- Subjects
- *
ACOUSTIC radiators , *SPEED of sound , *ACOUSTIC emission , *ORTHOGRAPHIC projection , *LINEAR equations , *LINEAR systems - Abstract
A closed-form method of acoustic emission (AE) source location for a velocity-free system using complete time difference of arrival (TDOA) measurements is proposed in this paper. First, this method established the governing equation of unknown acoustic velocity for each sensor; then, the governing equations of each of the three sensors were transformed into a linear equation, which can form a system of linear equations with the complete TDOA measurements. Third, the least squares solutions of the AE source coordinate and acoustic velocity were separately solved by an orthogonal projection operator. The proposed method was verified by the pencil-lead break experiment, and the results showed that the location accuracy and stability of the proposed method were better than those of traditional methods. Moreover, a simulation test was carried out to investigate the influence of noise scales on the location accuracy, and the results further prove that the proposed method holds higher noise immunity than the traditional methods. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
11. Acoustic Emission Mapping of Discharges in Spark Erosion Machining
- Author
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Smith, Craig, Koshy, Philip, and Mechanical Engineering
- Subjects
Manufacturing ,Electrical Discharge Machining (EDM) ,Mapping ,Acoustic Emission (AE) ,Spark Erosion Machining ,Source Location - Abstract
Electrical discharge machining (EDM) is a non-conventional machining process utilizing a series of electrical discharges to melt and vaporize workpiece material. In a wire EDM configuration wire breakage is a limiting factor in the machining productivity during the machining of workpieces with varying heights. Present methods of estimating workpiece height on-line in an effort to optimize machining parameters monitor the electrical signals for changes which may not be completely indicative of a change in workpiece height. This thesis intends to utilize acoustic emission (AE) sensors as a method for mapping the discharge location in order to estimate the workpiece height. This represents a novel approach as acoustic emission testing, while prevalent in the process monitoring of numerous conventional machining processes has yet to be significantly studied in combination with EDM. Another useful application of AE sensors with the EDM process under consideration is during the fast hole EDM process, where excessive wear is seen in the electrode causing true electrode length to remain uncertain. By using acoustic emission sensors to determine the true length of the electrode it could be possible to aid in the breakout detection of the electrode. Master of Applied Science (MASc)
- Published
- 2012
12. Source location error analysis and optimization methods
- Author
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Mao Chen Ge
- Subjects
source location ,Mathematical optimization ,Microseism ,Computer science ,least squares method ,BASIC DATA STRUCTURE ,Geotechnical Engineering and Engineering Geology ,Residual ,error ,residual ,acoustic emission (AE) ,Acoustic emission ,Error analysis ,microseismic (MS) ,Compatibility (mechanics) ,Comparison study ,Optimization methods ,absolute value method ,Algorithm - Abstract
The efficiency of an optimization method for acoustic emission/microseismic (AE/MS) source location is determined by the compatibility of its error definition with the errors contained in the input data. This compatibility can be examined in terms of the distribution of station residuals. For an ideal distribution, the input error is held at the station where it takes place as the station residual and the error is not permitted to spread to other stations. A comparison study of two optimization methods, namely the least squares method and the absolute value method, shows that the distribution with this character constrains the input errors and minimizes their impact, which explains the much more robust performance by the absolute value method in dealing with large and isolated input errors. When the errors in the input data are systematic and/or extreme in that the basic data structure is altered by these errors, none of the optimization methods are able to function. The only means to resolve this problem is the early detection and correction of these errors through a data screening process. An efficient data screening process is of primary importance for AE/MS source location. In addition to its critical role in dealing with those systematic and extreme errors, data screening creates a favorable environment for applying optimization methods.
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