Nathan Geib, S. Wallen, M. Haberman, Christina J. Naify
Acoustic metamaterials exhibit effective material properties not found in naturally occurring media, and, as such, have received considerable attention for their potential applications in noise and vibration control, diagnostic imaging, and nonreciprocal transmission. Complementary acoustic metamaterials have been proposed as a means of compensating for the high impedance mismatches of aberrating layers that disrupt the acoustic field and hence distort acoustic images. More recently, a complementary acoustic metamaterial featuring active components was shown in principal to compensate for both the impedance mismatch and energy attenuation of lossy materials, but a physical realization of the concept has not yet been implemented. Here, we present results from a one-dimensional acoustic model showing how a plane wave incident on a lossy material can be augmented by point monopole and dipole sources to allow for near perfect transmission, thus rendering the lossy medium acoustically transparent. We present general expressions for source magnitudes that are dimensionless with respect to frequency, material thickness, and the background medium. We show that these results are consistent with three-dimensional finite element simulations, where the appropriate monopolar and dipolar forces are generated using finite dimensional velocity sources with real loudspeaker characteristics mounted in an acoustic waveguide.
{"title":"A model for near-perfect transmission through lossy media with acoustic sources","authors":"Nathan Geib, S. Wallen, M. Haberman, Christina J. Naify","doi":"10.3397/nc_2023_0071","DOIUrl":"https://doi.org/10.3397/nc_2023_0071","url":null,"abstract":"Acoustic metamaterials exhibit effective material properties not found in naturally occurring media, and, as such, have received considerable attention for their potential applications in noise and vibration control, diagnostic imaging, and nonreciprocal transmission. Complementary\u0000 acoustic metamaterials have been proposed as a means of compensating for the high impedance mismatches of aberrating layers that disrupt the acoustic field and hence distort acoustic images. More recently, a complementary acoustic metamaterial featuring active components was shown in principal\u0000 to compensate for both the impedance mismatch and energy attenuation of lossy materials, but a physical realization of the concept has not yet been implemented. Here, we present results from a one-dimensional acoustic model showing how a plane wave incident on a lossy material can be augmented\u0000 by point monopole and dipole sources to allow for near perfect transmission, thus rendering the lossy medium acoustically transparent. We present general expressions for source magnitudes that are dimensionless with respect to frequency, material thickness, and the background medium. We show\u0000 that these results are consistent with three-dimensional finite element simulations, where the appropriate monopolar and dipolar forces are generated using finite dimensional velocity sources with real loudspeaker characteristics mounted in an acoustic waveguide.","PeriodicalId":19195,"journal":{"name":"Noise & Health","volume":"126 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75368778","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A complicated source can be represented by a series of acoustic free velocity sources. The sound pressure at a position in the field can be predicted by summing the products of the acoustic free velocity source strengths and their respective transfer functions. These transfer functions relate the sound pressure in the field to the acoustic source strength. In this research, the sound pressure is measured at positions in the free field and then is used to determine the acoustic free velocity source strengths via an inverse method. The approach is applied to characterize a laboratory source with high directivity. It is then demonstrated that the sources can be used to predict the insertion loss of a barrier introduced to block the source from the receiver.
{"title":"Prediction of sound radiation using reconstructed acoustic free velocity sources","authors":"Xin Yan, D. Herrin","doi":"10.3397/nc_2023_0057","DOIUrl":"https://doi.org/10.3397/nc_2023_0057","url":null,"abstract":"A complicated source can be represented by a series of acoustic free velocity sources. The sound pressure at a position in the field can be predicted by summing the products of the acoustic free velocity source strengths and their respective transfer functions. These transfer functions relate the sound pressure in the field to the acoustic source strength. In this research, the sound pressure is measured at positions in the free field and then is used to determine the acoustic free velocity source strengths via an inverse method. The approach is applied to characterize a laboratory source with high directivity. It is then demonstrated that the sources can be used to predict the insertion loss of a barrier introduced to block the source from the receiver.","PeriodicalId":19195,"journal":{"name":"Noise & Health","volume":"34 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88481041","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P. Gilmore, U. Gandhi, S. M. S. Shaihan, R. Rangarajan
Quasi-zero stiffness isolators are a promising technology to reduce vibration transmission over a large frequency range while maintaining passive operation and low cost. Many different types of QZS isolators have been demonstrated utilizing a variety of mechanical, pneumatic, and magnetic components. While some of these types have their own unique challenges, other challenges are more general. Two of these challenges are mass sensitivity and hysteresis in the load-deflection curve caused by snap-through buckling, friction, or structural damping. This work investigates the impact of force-deflection hysteresis on isolation performance through experimental techniques. Results show that increasing hysteresis reduces the mass sensitivity but worsens the isolation performance at low frequencies. A tradeoff must be made between these two aspects but can be overcome by shifting the QZS region to difference forces. A simple method to achieve this adaptability exists for certain types of QZS structures, therefore enabling a variety of practical applications within a certain design window.
{"title":"Tradeoff between mass sensitivity and performance in quasi-zero stiffness vibration isolators","authors":"P. Gilmore, U. Gandhi, S. M. S. Shaihan, R. Rangarajan","doi":"10.3397/nc_2023_0139","DOIUrl":"https://doi.org/10.3397/nc_2023_0139","url":null,"abstract":"Quasi-zero stiffness isolators are a promising technology to reduce vibration transmission over a large frequency range while maintaining passive operation and low cost. Many different types of QZS isolators have been demonstrated utilizing a variety of mechanical, pneumatic, and magnetic\u0000 components. While some of these types have their own unique challenges, other challenges are more general. Two of these challenges are mass sensitivity and hysteresis in the load-deflection curve caused by snap-through buckling, friction, or structural damping. This work investigates the impact\u0000 of force-deflection hysteresis on isolation performance through experimental techniques. Results show that increasing hysteresis reduces the mass sensitivity but worsens the isolation performance at low frequencies. A tradeoff must be made between these two aspects but can be overcome by shifting\u0000 the QZS region to difference forces. A simple method to achieve this adaptability exists for certain types of QZS structures, therefore enabling a variety of practical applications within a certain design window.","PeriodicalId":19195,"journal":{"name":"Noise & Health","volume":"68 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74761374","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A few case studies regarding public utility and transportation noise are presented. These address concerns regarding the prediction and attenuation of noise from electrical transformers, gas regulators, and interstate highways. Our approach to computer modeling, model adjustments to match measured conditions, and before/after measurements will be presented.
{"title":"Validation of utility and transportation noise modeling","authors":"M. Conaway, Joseph A. Keefe","doi":"10.3397/nc_2023_0028","DOIUrl":"https://doi.org/10.3397/nc_2023_0028","url":null,"abstract":"A few case studies regarding public utility and transportation noise are presented. These address concerns regarding the prediction and attenuation of noise from electrical transformers, gas regulators, and interstate highways. Our approach to computer modeling, model adjustments to\u0000 match measured conditions, and before/after measurements will be presented.","PeriodicalId":19195,"journal":{"name":"Noise & Health","volume":"25 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72999440","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Brigham Young University has been studying questions related to NASA X-59 community noise testing. A summary of the key findings and recommendations to date are presented. Among these are weather-resistant ground microphone setups that reduce wind noise, methods for treating the problem of ambient noise contamination on sonic boom metrics and spectra, and the turbulence-induced variability seen over relatively small-aperture arrays. Also discussed are recommendations for data post-processing, e.g., employing a digital pole-shifting filter and zero-padding to improve the fidelity and smoothness of low-frequency spectral data. Finally, the relative merits of various sonic boom metrics are considered. Although Perceived Level has been the most widely-used metric, it is relatively sensitive to ambient noise contamination and turbulence-induced variability. [Work supported by NASA Langley Research Center through the National Institute of Aerospace.]
{"title":"Towards high-quality X-59 sonic thump measurements","authors":"Mark C. Anderson, K. Gee, J. Durrant, A. Loubeau","doi":"10.3397/nc_2023_0144","DOIUrl":"https://doi.org/10.3397/nc_2023_0144","url":null,"abstract":"Brigham Young University has been studying questions related to NASA X-59 community noise testing. A summary of the key findings and recommendations to date are presented. Among these are weather-resistant ground microphone setups that reduce wind noise, methods for treating the problem\u0000 of ambient noise contamination on sonic boom metrics and spectra, and the turbulence-induced variability seen over relatively small-aperture arrays. Also discussed are recommendations for data post-processing, e.g., employing a digital pole-shifting filter and zero-padding to improve the fidelity\u0000 and smoothness of low-frequency spectral data. Finally, the relative merits of various sonic boom metrics are considered. Although Perceived Level has been the most widely-used metric, it is relatively sensitive to ambient noise contamination and turbulence-induced variability. [Work supported\u0000 by NASA Langley Research Center through the National Institute of Aerospace.]","PeriodicalId":19195,"journal":{"name":"Noise & Health","volume":"10 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84282785","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Statistical energy analysis (SEA) is a vibro-acoustic modeling technique suitable for systems where high modal densities exist. Traditionally SEA is used for predicting system response in higher frequency bands. However, for systems such as an air-handler that contain large, flat panels constructed of sheet metal the usefulness of SEA stretches into mid and lower frequency bands as well. Measured results of an air-handling cabinet were obtained by spatially averaging accelerations of cabinet surfaces caused by an input of white noise into the cabinet side by a shaker. Energy from each sub-panel of the cabinet was normalized with the panel into which the energy was input for easy comparison with modeled data. A simplified model of the air-handling cabinet processed in VA One software yielded results generally within 10 dB of measured results. Some lower frequency band limitations were realized due to cabinet geometry and construction. These results focus primarily on the structure and less so on the acoustic volume of the air-handling cabinet.
{"title":"Statistical energy analysis simulation of an air-handling cabinet","authors":"Matt Smither, D. Herrin","doi":"10.3397/nc_2023_0070","DOIUrl":"https://doi.org/10.3397/nc_2023_0070","url":null,"abstract":"Statistical energy analysis (SEA) is a vibro-acoustic modeling technique suitable for systems where high modal densities exist. Traditionally SEA is used for predicting system response in higher frequency bands. However, for systems such as an air-handler that contain large, flat panels\u0000 constructed of sheet metal the usefulness of SEA stretches into mid and lower frequency bands as well. Measured results of an air-handling cabinet were obtained by spatially averaging accelerations of cabinet surfaces caused by an input of white noise into the cabinet side by a shaker. Energy\u0000 from each sub-panel of the cabinet was normalized with the panel into which the energy was input for easy comparison with modeled data. A simplified model of the air-handling cabinet processed in VA One software yielded results generally within 10 dB of measured results. Some lower frequency\u0000 band limitations were realized due to cabinet geometry and construction. These results focus primarily on the structure and less so on the acoustic volume of the air-handling cabinet.","PeriodicalId":19195,"journal":{"name":"Noise & Health","volume":"30 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88852772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jeremy Plé, Tenon Charly Kone, Alla Eddine Benchikh Lehocine, R. Panneton
In a society where the vast majority of people spend their time inside buildings or vehicles, the need to filter the air is essential to ensure a certain level of comfort. The integration of air exchanger systems in these enclosed spaces generates noise pollution which can deteriorate the quality of the air. Thus, controlling the noise generated by these systems becomes a major challenge for the construction industry. Recent traditional solutions such as acoustic sonic crystals only allow high frequency noise control. One solution is the incorporation of inner structured acoustic materials for the control of low frequency transmission. This paper proposes a coupling of sonic crystals and structural acoustic materials for the control of sound transmission at low and high frequencies. To achieve this, research and simulations of the acoustic properties of various metamaterial models under the COMSOL software were established as well as a system of the selected solutions, using the transfer matrix method. Experimental impedance tube analyses are being carried out for varying geometries, along with a fabrication method for prototyping.
{"title":"Sound attenuation by acoustic metamaterials applied to kitchen hoods","authors":"Jeremy Plé, Tenon Charly Kone, Alla Eddine Benchikh Lehocine, R. Panneton","doi":"10.3397/nc_2023_0044","DOIUrl":"https://doi.org/10.3397/nc_2023_0044","url":null,"abstract":"In a society where the vast majority of people spend their time inside buildings or vehicles, the need to filter the air is essential to ensure a certain level of comfort. The integration of air exchanger systems in these enclosed spaces generates noise pollution which can deteriorate\u0000 the quality of the air. Thus, controlling the noise generated by these systems becomes a major challenge for the construction industry. Recent traditional solutions such as acoustic sonic crystals only allow high frequency noise control. One solution is the incorporation of inner structured\u0000 acoustic materials for the control of low frequency transmission. This paper proposes a coupling of sonic crystals and structural acoustic materials for the control of sound transmission at low and high frequencies. To achieve this, research and simulations of the acoustic properties of various\u0000 metamaterial models under the COMSOL software were established as well as a system of the selected solutions, using the transfer matrix method. Experimental impedance tube analyses are being carried out for varying geometries, along with a fabrication method for prototyping.","PeriodicalId":19195,"journal":{"name":"Noise & Health","volume":"278 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83072462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Live music is hosted at many small restaurants and breweries as a means for attracting customers and helping to expose patrons to local bands. Outdoor live music, especially during warm spring and summer seasons provides flexibility for venues in terms of seating capacity, patron comfort, and the integration of natural scenery. However, sound from outdoor entertainment can be a vexing problem for the surrounding community, especially for late evening and nighttime performances. In response to community concerns, outdoor live music venues located in three different communities (rural, small town urban, and waterfront) were each required to provide in-situ demonstrations to assess the effect of outdoor music on nearby homes. The effectiveness of these demonstrations, along with an analysis of mitigation measures, is discussed.
{"title":"Evaluation and mitigation of outdoor live music","authors":"H. Singleton","doi":"10.3397/nc_2023_0078","DOIUrl":"https://doi.org/10.3397/nc_2023_0078","url":null,"abstract":"Live music is hosted at many small restaurants and breweries as a means for attracting customers and helping to expose patrons to local bands. Outdoor live music, especially during warm spring and summer seasons provides flexibility for venues in terms of seating capacity, patron comfort,\u0000 and the integration of natural scenery. However, sound from outdoor entertainment can be a vexing problem for the surrounding community, especially for late evening and nighttime performances. In response to community concerns, outdoor live music venues located in three different communities\u0000 (rural, small town urban, and waterfront) were each required to provide in-situ demonstrations to assess the effect of outdoor music on nearby homes. The effectiveness of these demonstrations, along with an analysis of mitigation measures, is discussed.","PeriodicalId":19195,"journal":{"name":"Noise & Health","volume":"1 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76238726","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Spring-supported concrete floating floors are often used as a high-end solution to mitigate noise and vibration disturbances in fitness centers. Suppliers of these floors typically provide impressive sound test results, but information regarding their low-frequency vibration isolation capabilities is scarce. In this study, the authors collected in-situ vibration data from an existing fitness center equipped with a 4-in (102-mm) thick spring-supported concrete floating floor while conducting various activities such as running on a treadmill, dropping a dumbbell, putting down a barbell and slamming a medicine ball on the floor. Frequency measurements revealed that entrapped air led to an increase in the natural frequency of the floating floor. The data demonstrated that floating slab effectively isolated noise and high-frequency vibrations, but was not able to isolate low-frequency vibrations. Additionally, a finite element model of the structure was developed, incorporating the floating floor and the base structural slab. The model was used to simulate treadmill running and weight drops, and calculated vibration levels were presented as heat maps across the entire floor. The model's predictions aligned closely with the actual measurements, demonstrating that vibration analysis based on finite element models is a valuable method to design effective mitigation strategies for fitness centers.
{"title":"Vibration Isolation with Spring Supported Concrete Floating Floors on Fitness Centers","authors":"Omer F. Tigli, M. Royvaran","doi":"10.3397/nc_2023_0090","DOIUrl":"https://doi.org/10.3397/nc_2023_0090","url":null,"abstract":"Spring-supported concrete floating floors are often used as a high-end solution to mitigate noise and vibration disturbances in fitness centers. Suppliers of these floors typically provide impressive sound test results, but information regarding their low-frequency vibration isolation\u0000 capabilities is scarce. In this study, the authors collected in-situ vibration data from an existing fitness center equipped with a 4-in (102-mm) thick spring-supported concrete floating floor while conducting various activities such as running on a treadmill, dropping a dumbbell, putting\u0000 down a barbell and slamming a medicine ball on the floor. Frequency measurements revealed that entrapped air led to an increase in the natural frequency of the floating floor. The data demonstrated that floating slab effectively isolated noise and high-frequency vibrations, but was not able\u0000 to isolate low-frequency vibrations. Additionally, a finite element model of the structure was developed, incorporating the floating floor and the base structural slab. The model was used to simulate treadmill running and weight drops, and calculated vibration levels were presented as heat\u0000 maps across the entire floor. The model's predictions aligned closely with the actual measurements, demonstrating that vibration analysis based on finite element models is a valuable method to design effective mitigation strategies for fitness centers.","PeriodicalId":19195,"journal":{"name":"Noise & Health","volume":"12 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85404375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Heating, Ventilation and Air Conditioning (HVAC), are crucial in every building for the well being of the occupants. While these equipments take care of the air quality with exhausting polluted air out and bringing fresh air in, they can let a polluant in: noise. Noise can have non-physical effects like disturbed sleep, cognitive problems or even influences on heart diseases. Recent developments in the acoustic field shown the use of metamaterials that can reduce noise while keeping good ventilation. The sonic crystals, disposed in a certain pattern following the Bragg's law, can be tuned to reduce noise on a wide frequency band. The design of an air vent, known as a metacage, was made by using open source numerical simulations. Based on a numerical plan and optimization methods, this study's goal was to find the optimal solution for the HVAC to reduce noise while minimizing ventilation loss. Following the simulations results, the metacage generated was 3D printed for validation in the laboratory, showing the corroboration with the simulations. The final results show third-octave bands with a TL peak over 10dB and an average of 3dB for all the others bands up to 10kHz. All this while keeping minimal ventilation loss.
{"title":"Air vent shape optimization with metamaterials.","authors":"Marco Lizotte, R. Panneton, J. Piaud","doi":"10.3397/nc_2023_0111","DOIUrl":"https://doi.org/10.3397/nc_2023_0111","url":null,"abstract":"Heating, Ventilation and Air Conditioning (HVAC), are crucial in every building for the well being of the occupants. While these equipments take care of the air quality with exhausting polluted air out and bringing fresh air in, they can let a polluant in: noise. Noise can have non-physical\u0000 effects like disturbed sleep, cognitive problems or even influences on heart diseases. Recent developments in the acoustic field shown the use of metamaterials that can reduce noise while keeping good ventilation. The sonic crystals, disposed in a certain pattern following the Bragg's law,\u0000 can be tuned to reduce noise on a wide frequency band. The design of an air vent, known as a metacage, was made by using open source numerical simulations. Based on a numerical plan and optimization methods, this study's goal was to find the optimal solution for the HVAC to reduce noise while\u0000 minimizing ventilation loss. Following the simulations results, the metacage generated was 3D printed for validation in the laboratory, showing the corroboration with the simulations. The final results show third-octave bands with a TL peak over 10dB and an average of 3dB for all the others\u0000 bands up to 10kHz. All this while keeping minimal ventilation loss.","PeriodicalId":19195,"journal":{"name":"Noise & Health","volume":"30 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82095622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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