This paper presents another application of an images group model for a special enclosure geometry and source orientation. A previous work outlined the concept via application to a special tight-fitting enclosure. Application of the concept to a fan plenum requires different mathematical descriptions for the image groups. This paper describes the sound reverberation inside a sound enclosure with mostly open sides where the primary noise sources are the air inlets and exhausts of axial type fans located at the top of the enclosure, the sound transmission through the air inlet openings, and the radiation to wayside positions. The main reverberation between the floor and ceiling is determined with an image based mathematical model. The model considers how the main reverberant part image group is amplified by its images from two parallel bulkheads and any side wall frame members. The method of images approach allows the hard surfaces of an untreated plenum to be represented by perfectly reflecting surfaces with zero sound absorption coefficients, thus not requiring any estimate or measurement for these surfaces. Numerical results show excellent comparison to experimental results for an actual plenum. The image model is also shown to be significantly more accurate than the standard large room diffuse field reverberant model.
{"title":"An Image Based Mathematical Model for the Propagation of Fan Noise in a Plenum with Large Side Openings","authors":"Michael J. Panza","doi":"10.1155/2015/361678","DOIUrl":"https://doi.org/10.1155/2015/361678","url":null,"abstract":"This paper presents another application of an images group model for a special enclosure geometry and source orientation. A previous work outlined the concept via application to a special tight-fitting enclosure. Application of the concept to a fan plenum requires different mathematical descriptions for the image groups. This paper describes the sound reverberation inside a sound enclosure with mostly open sides where the primary noise sources are the air inlets and exhausts of axial type fans located at the top of the enclosure, the sound transmission through the air inlet openings, and the radiation to wayside positions. The main reverberation between the floor and ceiling is determined with an image based mathematical model. The model considers how the main reverberant part image group is amplified by its images from two parallel bulkheads and any side wall frame members. The method of images approach allows the hard surfaces of an untreated plenum to be represented by perfectly reflecting surfaces with zero sound absorption coefficients, thus not requiring any estimate or measurement for these surfaces. Numerical results show excellent comparison to experimental results for an actual plenum. The image model is also shown to be significantly more accurate than the standard large room diffuse field reverberant model.","PeriodicalId":44068,"journal":{"name":"Advances in Acoustics and Vibration","volume":"2015 1","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2015-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2015/361678","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64921082","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Time-frequency representation algorithms such as spectrograms have proven to be useful tools in marine biosonar signal analysis. Although there are several different time-frequency representation algorithms designed for different types of signals with various characteristics, it is unclear which algorithms that are best suited for transient signals, like the echolocation signals of echolocating whales. This paper describes a comparison of seven different time-frequency representation algorithms with respect to their usefulness when it comes to marine biosonar signals. It also provides the answer to how close in time and frequency two transients can be while remaining distinguishable as two separate signals in time-frequency representations. This is, for instance, relevant in studies where echolocation signal component azimuths are compared in the search for the exact location of their acoustic sources. The smallest time difference was found to be 20 µs and the smallest frequency difference 49 kHz of signals with a −3 dB bandwidth of 40 kHz. Among the tested methods, the Reassigned Smoothed Pseudo Wigner-Ville distribution technique was found to be the most capable of localizing closely spaced signal components.
{"title":"Evaluation of seven time-frequency representation algorithms applied to broadband echolocation signals","authors":"Josefin Starkhammar, M. Hansson-Sandsten","doi":"10.1155/2015/342503","DOIUrl":"https://doi.org/10.1155/2015/342503","url":null,"abstract":"Time-frequency representation algorithms such as spectrograms have proven to be useful tools in marine biosonar signal analysis. Although there are several different time-frequency representation algorithms designed for different types of signals with various characteristics, it is unclear which algorithms that are best suited for transient signals, like the echolocation signals of echolocating whales. This paper describes a comparison of seven different time-frequency representation algorithms with respect to their usefulness when it comes to marine biosonar signals. It also provides the answer to how close in time and frequency two transients can be while remaining distinguishable as two separate signals in time-frequency representations. This is, for instance, relevant in studies where echolocation signal component azimuths are compared in the search for the exact location of their acoustic sources. The smallest time difference was found to be 20 µs and the smallest frequency difference 49 kHz of signals with a −3 dB bandwidth of 40 kHz. Among the tested methods, the Reassigned Smoothed Pseudo Wigner-Ville distribution technique was found to be the most capable of localizing closely spaced signal components.","PeriodicalId":44068,"journal":{"name":"Advances in Acoustics and Vibration","volume":"2015 1","pages":"1-13"},"PeriodicalIF":0.0,"publicationDate":"2015-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2015/342503","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64908375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Y. Sidibé, F. Druaux, D. Lefebvre, F. Léon, G. Maze
Detection and diagnosis method is proposed for surface damage in immersed structures. It is based on noncontact ultrasonic echography measurements, signal processing tools, and artificial intelligence methods. Significant features are extracted from the measured signals and a classification method is developed to detect the echoes resulting from surface damage in an immersed structure. The identification of the damage is also provided. Gaussian neural networks trained with a specific learning algorithm are developed for this purpose. The performance of the method is validated by laboratory experiments which indicate that this method could be suitable for the monitoring of inaccessible systems like marine turbines whose unavailability causes severe economic losses.
{"title":"A Noncontact Method for the Detection and Diagnosis of Surface Damage in Immersed Structures","authors":"Y. Sidibé, F. Druaux, D. Lefebvre, F. Léon, G. Maze","doi":"10.1155/2015/429749","DOIUrl":"https://doi.org/10.1155/2015/429749","url":null,"abstract":"Detection and diagnosis method is proposed for surface damage in immersed structures. It is based on noncontact ultrasonic echography measurements, signal processing tools, and artificial intelligence methods. Significant features are extracted from the measured signals and a classification method is developed to detect the echoes resulting from surface damage in an immersed structure. The identification of the damage is also provided. Gaussian neural networks trained with a specific learning algorithm are developed for this purpose. The performance of the method is validated by laboratory experiments which indicate that this method could be suitable for the monitoring of inaccessible systems like marine turbines whose unavailability causes severe economic losses.","PeriodicalId":44068,"journal":{"name":"Advances in Acoustics and Vibration","volume":"2015 1","pages":"1-10"},"PeriodicalIF":0.0,"publicationDate":"2015-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2015/429749","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64961628","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An exact solution for free vibrations of a series of uniform Euler-Bernoulli beams connected by Kelvin-Voigt is developed. The beams have the same length and end conditions but can have different material or geometric properties. An example of five concentric beams connected by viscoelastic layers is considered.
{"title":"Free Vibrations of a Series of Beams Connected by Viscoelastic Layers","authors":"S. G. Kelly, Clint Nicely","doi":"10.1155/2015/976841","DOIUrl":"https://doi.org/10.1155/2015/976841","url":null,"abstract":"An exact solution for free vibrations of a series of uniform Euler-Bernoulli beams connected by Kelvin-Voigt is developed. The beams have the same length and end conditions but can have different material or geometric properties. An example of five concentric beams connected by viscoelastic layers is considered.","PeriodicalId":44068,"journal":{"name":"Advances in Acoustics and Vibration","volume":"2015 1","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2015-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2015/976841","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64191739","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper presents a novel hybrid fuzzy logic based artificial intelligence (AI) technique applicable to diagnosis of the crack parameters in a fixed-fixed beam by using the vibration signatures as input. The presence of damage in engineering structures leads to changes in vibration signatures like natural frequency and mode shapes. In the first part of this work, a structure with a failure crack has been analyzed using finite element method (FEM) and retrospective changes in the vibration signatures have been recorded. In the second part of the research work, these deviations in the vibration signatures for the first three mode shapes have been taken as input parameters for a fuzzy logic based controller for calculation of crack location and its severity as output parameters. In the proposed fuzzy controller, hybrid membership functions have been taken. Several fuzzy rules have been identified for prediction of crack depth and location and the results have been compared with finite element analysis. A database of experimental results has also been considered to check the robustness of the fuzzy controller. The results show that predictions for the nondimensional crack location, , deviate ~2.4% from experimental values and for the nondimensional crack depth, , are less than ~−2%.
{"title":"Fault Diagnosis of Beam-Like Structure Using Modified Fuzzy Technique","authors":"D. Thatoi, S. Choudhury, P. K. Jena","doi":"10.1155/2014/491510","DOIUrl":"https://doi.org/10.1155/2014/491510","url":null,"abstract":"This paper presents a novel hybrid fuzzy logic based artificial intelligence (AI) technique applicable to diagnosis of the crack parameters in a fixed-fixed beam by using the vibration signatures as input. The presence of damage in engineering structures leads to changes in vibration signatures like natural frequency and mode shapes. In the first part of this work, a structure with a failure crack has been analyzed using finite element method (FEM) and retrospective changes in the vibration signatures have been recorded. In the second part of the research work, these deviations in the vibration signatures for the first three mode shapes have been taken as input parameters for a fuzzy logic based controller for calculation of crack location and its severity as output parameters. In the proposed fuzzy controller, hybrid membership functions have been taken. Several fuzzy rules have been identified for prediction of crack depth and location and the results have been compared with finite element analysis. A database of experimental results has also been considered to check the robustness of the fuzzy controller. The results show that predictions for the nondimensional crack location, , deviate ~2.4% from experimental values and for the nondimensional crack depth, , are less than ~−2%.","PeriodicalId":44068,"journal":{"name":"Advances in Acoustics and Vibration","volume":"2014 1","pages":"1-18"},"PeriodicalIF":0.0,"publicationDate":"2014-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2014/491510","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64518782","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Investigations of modal parameters for a mistuned packet of turbine blades due to lacing wire damage are reported using analytical and numerical studies with a simplified model. The turbine blade is assumed to be an Euler-Bernoulli beam connected with a lacing wire which is modeled as a mass less linear elastic spring. Thus, the blade is considered as a continuous system and lacing wire as a discrete system. The analytical results using Eigen value analysis are compared with numerical results obtained using commercial finite element package. In real life situation, though not reported in the literature, it is the failure of lacing wire that occurs quite often compared to the turbine blade and acts as precursor to the subsequent blade damage if it goes undetected. Therefore, studying the modal parameters of the grouped turbine blades in the context of lacing wire failure becomes important. The effect of variation of lacing wire location and stiffness indicative of damage resulting in the loss of stiffness on modal parameters is investigated. The study reveals a lot of fundamental understandings pertaining to dynamic behavior of grouped blades compared to the stand-alone blade under the influence of damaged lacing wire.
{"title":"Analytical and Numerical Investigation of Lacing Wire Damage Induced Mistuning in Turbine Blade Packet","authors":"M. Kotambkar, Animesh Chatterjee","doi":"10.1155/2014/164638","DOIUrl":"https://doi.org/10.1155/2014/164638","url":null,"abstract":"Investigations of modal parameters for a mistuned packet of turbine blades due to lacing wire damage are reported using analytical and numerical studies with a simplified model. The turbine blade is assumed to be an Euler-Bernoulli beam connected with a lacing wire which is modeled as a mass less linear elastic spring. Thus, the blade is considered as a continuous system and lacing wire as a discrete system. The analytical results using Eigen value analysis are compared with numerical results obtained using commercial finite element package. In real life situation, though not reported in the literature, it is the failure of lacing wire that occurs quite often compared to the turbine blade and acts as precursor to the subsequent blade damage if it goes undetected. Therefore, studying the modal parameters of the grouped turbine blades in the context of lacing wire failure becomes important. The effect of variation of lacing wire location and stiffness indicative of damage resulting in the loss of stiffness on modal parameters is investigated. The study reveals a lot of fundamental understandings pertaining to dynamic behavior of grouped blades compared to the stand-alone blade under the influence of damaged lacing wire.","PeriodicalId":44068,"journal":{"name":"Advances in Acoustics and Vibration","volume":"2014 1","pages":"1-16"},"PeriodicalIF":0.0,"publicationDate":"2014-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2014/164638","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64374181","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper is concerned with the sinking of the Korean naval warship (ROKS Cheonan) and the reported spectra of the seismic signals recorded at the time of the incident. The spectra of seismic signals show prominently amplitude peaks at around 8.5 Hz and its harmonics. These frequencies were explained with the vibrations of a water column due to an underwater explosion. This explanation is highly doubtful and concerns about its validity have already been raised in the scientific community. In this work an alternative explanation is presented: it is shown that the recorded seismic spectra are consistent with the natural frequencies of vibrations of a large submarine with a length of around 113 m. This finding raises the possibility that the ROKS Cheonan sunk because of the collision with a large submarine rather than the explosion of a torpedo or an underwater mine.
{"title":"What Really Caused the ROKS Cheonan Warship Sinking","authors":"Hwang-Su Kim, M. Caresta","doi":"10.1155/2014/514346","DOIUrl":"https://doi.org/10.1155/2014/514346","url":null,"abstract":"This paper is concerned with the sinking of the Korean naval warship (ROKS Cheonan) and the reported spectra of the seismic signals recorded at the time of the incident. The spectra of seismic signals show prominently amplitude peaks at around 8.5 Hz and its harmonics. These frequencies were explained with the vibrations of a water column due to an underwater explosion. This explanation is highly doubtful and concerns about its validity have already been raised in the scientific community. In this work an alternative explanation is presented: it is shown that the recorded seismic spectra are consistent with the natural frequencies of vibrations of a large submarine with a length of around 113 m. This finding raises the possibility that the ROKS Cheonan sunk because of the collision with a large submarine rather than the explosion of a torpedo or an underwater mine.","PeriodicalId":44068,"journal":{"name":"Advances in Acoustics and Vibration","volume":"44 4 1","pages":"1-10"},"PeriodicalIF":0.0,"publicationDate":"2014-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2014/514346","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64529395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The occurrence of an overlapping signal is a significant problem in performing multiple objects localization. Doppler velocity is sensitive to the echo shape and is also able to be connected to the physical properties of moving objects, especially for a pulse compression ultrasonic signal. The expectation-maximization (EM) algorithm has the ability to achieve signal separation. Thus, applying the EM algorithm to the overlapping pulse compression signals is of interest. This paper describes a proposed method, based on the EM algorithm, of Doppler velocity estimation for overlapping linear-period-modulated (LPM) ultrasonic signals. Simulations are used to validate the proposed method.
{"title":"Doppler Velocity Estimation of Overlapping Linear-Period-Modulated Ultrasonic Waves Based on an Expectation-Maximization Algorithm","authors":"N. Thong-un, M. Kurosawa","doi":"10.1155/2014/921876","DOIUrl":"https://doi.org/10.1155/2014/921876","url":null,"abstract":"The occurrence of an overlapping signal is a significant problem in performing multiple objects localization. Doppler velocity is sensitive to the echo shape and is also able to be connected to the physical properties of moving objects, especially for a pulse compression ultrasonic signal. The expectation-maximization (EM) algorithm has the ability to achieve signal separation. Thus, applying the EM algorithm to the overlapping pulse compression signals is of interest. This paper describes a proposed method, based on the EM algorithm, of Doppler velocity estimation for overlapping linear-period-modulated (LPM) ultrasonic signals. Simulations are used to validate the proposed method.","PeriodicalId":44068,"journal":{"name":"Advances in Acoustics and Vibration","volume":"2014 1","pages":"1-7"},"PeriodicalIF":0.0,"publicationDate":"2014-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2014/921876","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64743982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Zagrouba, M. S. Bouhdima, M. S. Bouhdima, M. Ghozlen
The present work deals with functionally graded materials (FGM) isotropic plates in the neighborhood of the first-order symmetric zero group velocity (S1-ZGV) point. The mechanical properties of functionally graded material (FGM) are assumed to vary continuously through the thickness of the plate and obey a power law of the volume fraction of the constituents. Governing equations for the problem are derived, and the power series technique (PST) is employed to solve the recursive equations. The impact of the FGM basic materials properties on S1-ZGV frequency of FGM plate is investigated. Numerical results show that S1-ZGV frequency is comparatively more sensitive to the shear modulus. The gradient coefficient does not affect the linear dependence of ZGV frequency as function of cut-off frequency ; only the slope is slightly varied.
{"title":"S1-ZGV Modes of a Linear and Nonlinear Profile for Functionally Graded Material Using Power Series Technique","authors":"M. Zagrouba, M. S. Bouhdima, M. S. Bouhdima, M. Ghozlen","doi":"10.1155/2014/401042","DOIUrl":"https://doi.org/10.1155/2014/401042","url":null,"abstract":"The present work deals with functionally graded materials (FGM) isotropic plates in the neighborhood of the first-order symmetric zero group velocity (S1-ZGV) point. The mechanical properties of functionally graded material (FGM) are assumed to vary continuously through the thickness of the plate and obey a power law of the volume fraction of the constituents. Governing equations for the problem are derived, and the power series technique (PST) is employed to solve the recursive equations. The impact of the FGM basic materials properties on S1-ZGV frequency of FGM plate is investigated. Numerical results show that S1-ZGV frequency is comparatively more sensitive to the shear modulus. The gradient coefficient does not affect the linear dependence of ZGV frequency as function of cut-off frequency ; only the slope is slightly varied.","PeriodicalId":44068,"journal":{"name":"Advances in Acoustics and Vibration","volume":"2014 1","pages":"1-7"},"PeriodicalIF":0.0,"publicationDate":"2014-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2014/401042","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64479878","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sound scattering by a Janus sphere type is considered. The sphere has two surface zones: a soft surface of zero acoustic impedance and a hard surface of infinite acoustic impedance. The zones are arranged such that axisymmetry of the sound field is preserved. The equivalent source method is used to compute the sound field. It is shown that, by varying the sizes of the soft and hard zones on the sphere, a significant reduction can be achieved in the scattered acoustic power and upstream directivity when the sphere is near a free surface and its soft zone faces the incoming wave and vice versa for a hard ground. In both cases the size of the sphere’s hard zone is much larger than that of its soft zone. The boundary location between the two zones coincides with the location of a zero pressure line of the incoming standing sound wave, thus masking the sphere within the sound field reflected by the free surface or the hard ground. The reduction in the scattered acoustic power diminishes when the sphere is placed in free space. Variations of the scattered acoustic power and directivity with the sound frequency are also given and discussed.
{"title":"Sound Scattering and Its Reduction by a Janus Sphere Type","authors":"Deliya Kim, E. Avital, T. Miloh","doi":"10.1155/2014/392138","DOIUrl":"https://doi.org/10.1155/2014/392138","url":null,"abstract":"Sound scattering by a Janus sphere type is considered. The sphere has two surface zones: a soft surface of zero acoustic impedance and a hard surface of infinite acoustic impedance. The zones are arranged such that axisymmetry of the sound field is preserved. The equivalent source method is used to compute the sound field. It is shown that, by varying the sizes of the soft and hard zones on the sphere, a significant reduction can be achieved in the scattered acoustic power and upstream directivity when the sphere is near a free surface and its soft zone faces the incoming wave and vice versa for a hard ground. In both cases the size of the sphere’s hard zone is much larger than that of its soft zone. The boundary location between the two zones coincides with the location of a zero pressure line of the incoming standing sound wave, thus masking the sphere within the sound field reflected by the free surface or the hard ground. The reduction in the scattered acoustic power diminishes when the sphere is placed in free space. Variations of the scattered acoustic power and directivity with the sound frequency are also given and discussed.","PeriodicalId":44068,"journal":{"name":"Advances in Acoustics and Vibration","volume":"2014 1","pages":"1-11"},"PeriodicalIF":0.0,"publicationDate":"2014-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2014/392138","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64475906","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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