The proportion of box-girder bridges in high-speed railways in China is high. The noise caused by trains passing a box-girder bridge is more intense than the noise in other sections of the railway because it is radiated by the bridge. This study investigates the acoustic radiation characteristics and mechanism of the box-girder bridge including low-frequency vibrations below the hearing threshold. The foregoing is examined in terms of natural vibration characteristics, vibration responses of the bridge under nonlinear train–track dynamic interactions, and structural noise radiation principle. The results show that the structural resonance, acoustic radiation efficiency, acoustic–vibration coupling in the bridge cavity, and severe train-induced vibrations play important roles in the acoustic radiation of the box-girder bridge. Under moving train loads, bridge vibrations are mainly in the 80- to 100-Hz frequency range and cause distinct noise radiation. Moreover, the low-frequency (20 Hz) train-induced vibrations of the bridge can generate distinct low-frequency noise. Additionally, the box-girder bridge cavity induces acoustic–vibration coupling, which can aggravate the noise radiation on both sides of the box-girder bridge.
{"title":"Case study: Acoustic radiation characteristics and mechanism of high-speed railway box-girder bridge","authors":"Xiaoan Zhang, Jianjin Yang","doi":"10.3397/1/377125","DOIUrl":"https://doi.org/10.3397/1/377125","url":null,"abstract":"The proportion of box-girder bridges in high-speed railways in China is high. The noise caused by trains passing a box-girder bridge is more intense than the noise in other sections of the railway because it is radiated by the bridge. This study investigates the acoustic radiation characteristics and mechanism of the box-girder bridge including low-frequency vibrations below the hearing threshold. The foregoing is examined in terms of natural vibration characteristics, vibration responses of the bridge under nonlinear train–track dynamic interactions, and structural noise radiation principle. The results show that the structural resonance, acoustic radiation efficiency, acoustic–vibration coupling in the bridge cavity, and severe train-induced vibrations play important roles in the acoustic radiation of the box-girder bridge. Under moving train loads, bridge vibrations are mainly in the 80- to 100-Hz frequency range and cause distinct noise radiation. Moreover, the low-frequency (20 Hz) train-induced vibrations of the bridge can generate distinct low-frequency noise. Additionally, the box-girder bridge cavity induces acoustic–vibration coupling, which can aggravate the noise radiation on both sides of the box-girder bridge.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135761900","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Q. Feng, Zhou Yang, W. Guo, Jianfei Lu, Yuxiong Liang
The vertical vibration band gap characteristics of the ballast track were investigated in this paper. The rail was simplified as a beam with double layer of periodic supports. The dispersion characteristics were studied considering the rail as Timoshenko beam, using the plane wave expansion method. The eigenvalue equation of the Timoshenko beam with complex boundary conditions, which was a problem for the traditional plane wave expansion method, has been solved using special mathematical solution of matrix inversion. The band gap of the flexural waves in periodic track structure was confirmed by the rail vibration transmission characteristics obtained from the experiments. The physical significance of band gap frequency was analyzed in detail in this paper. In addition, we give a more accurate prediction model of Bragg band gap frequency of periodic track structure compared previous studies. The band gap of the flexural waves in periodic track structure was confirmed by the rail vibration transmission characteristics obtained from the experiments. The influence of temperature force on the band gap characteristics of the flexural waves was also analyzed, and a sensitivity index of temperature force was given as a result. The results indicate that the square of the band gap frequency has a linear relation with the longitudinal temperature force, which is different from the previous research.
{"title":"The propagation characteristics of flexural wave in periodic ballast track","authors":"Q. Feng, Zhou Yang, W. Guo, Jianfei Lu, Yuxiong Liang","doi":"10.3397/1/377120","DOIUrl":"https://doi.org/10.3397/1/377120","url":null,"abstract":"The vertical vibration band gap characteristics of the ballast track were investigated in this paper. The rail was simplified as a beam with double layer of periodic supports. The dispersion characteristics were studied considering the rail as Timoshenko beam, using the plane wave expansion\u0000 method. The eigenvalue equation of the Timoshenko beam with complex boundary conditions, which was a problem for the traditional plane wave expansion method, has been solved using special mathematical solution of matrix inversion. The band gap of the flexural waves in periodic track structure\u0000 was confirmed by the rail vibration transmission characteristics obtained from the experiments. The physical significance of band gap frequency was analyzed in detail in this paper. In addition, we give a more accurate prediction model of Bragg band gap frequency of periodic track structure\u0000 compared previous studies. The band gap of the flexural waves in periodic track structure was confirmed by the rail vibration transmission characteristics obtained from the experiments. The influence of temperature force on the band gap characteristics of the flexural waves was also analyzed,\u0000 and a sensitivity index of temperature force was given as a result. The results indicate that the square of the band gap frequency has a linear relation with the longitudinal temperature force, which is different from the previous research.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43938371","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
U-shaped Network (UNet) has shown excellent performance in a variety of speech enhancement tasks. However, because of the intrinsic limitation of convolutional operation, traditional UNet built with convolutional neural network (CNN) cannot learn global and long-term information well. In this work, we propose a new Swin-UNet-based speech enhancement method. Unlike the traditional UNet model, the CNN blocks are all replaced with Swin-Transformer blocks to explore more multi-scale contextual information. The Swin-UNet model employs shifted window mechanism which not only overcomes the defect of high computational complexity of the Transformer but also enhances global information interaction by utilizing the powerful global modeling capability of the Transformer. Through hierarchical Swin-Transformer blocks, global and local speech features can be fully leveraged to improve speech reconstruction ability. Experimental results confirm that the proposed method can eliminate more background noise while maintaining good objective speech quality.
{"title":"A new speech enhancement method based on Swin-UNet model","authors":"Chengli Sun, Weiqi Jiang, Y. Leng, Feilong Chen","doi":"10.3397/1/377122","DOIUrl":"https://doi.org/10.3397/1/377122","url":null,"abstract":"U-shaped Network (UNet) has shown excellent performance in a variety of speech enhancement tasks. However, because of the intrinsic limitation of convolutional operation, traditional UNet built with convolutional neural network (CNN) cannot learn global and long-term information well.\u0000 In this work, we propose a new Swin-UNet-based speech enhancement method. Unlike the traditional UNet model, the CNN blocks are all replaced with Swin-Transformer blocks to explore more multi-scale contextual information. The Swin-UNet model employs shifted window mechanism which not only\u0000 overcomes the defect of high computational complexity of the Transformer but also enhances global information interaction by utilizing the powerful global modeling capability of the Transformer. Through hierarchical Swin-Transformer blocks, global and local speech features can be fully leveraged\u0000 to improve speech reconstruction ability. Experimental results confirm that the proposed method can eliminate more background noise while maintaining good objective speech quality.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49218371","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Wafaa El Khatiri, Raef Cherif, Khalid El Bikri, Noureddine Atalla
In the aeronautical industry, the vibrations generated by mechanical systems produce unwanted noise perceived by users, which affects their comfort. Engineers encounter several difficulties in carrying out experimental measurements when studying complex systems. To solve this problem, a solution was proposed for the manufacturers' benefit, allowing them to access the various identified measurement points, describe the systems' vibroacoustic behavior, whether coupled or decoupled, and share the work between several teams and reduce the time spent on measurements. This paper deals with the experimental study performed on an aircraft noise abatement isolator. The component-based transfer path analysis hybrid inverse method is developed to allow the work on the subsystems separately between several teams and characterize them on an external test bench outside real functioning conditions. The studied system consists of a mass coupled by a noise abatement isolator fixed in an aluminum plate backed by a concrete cavity. Several parameters are studied such as the number of transfer paths to be considered to see the effect of neglecting certain transfer paths, the effects of coupling versus decoupling of the connected substructures and the number of indicator points chosen and used in the inversion method. The results are compared to the direct method.
{"title":"Case study: Hybrid inverse method for aircraft noise abatement isolator: Experimental and vibroacoustic assessment","authors":"Wafaa El Khatiri, Raef Cherif, Khalid El Bikri, Noureddine Atalla","doi":"10.3397/1/377124","DOIUrl":"https://doi.org/10.3397/1/377124","url":null,"abstract":"In the aeronautical industry, the vibrations generated by mechanical systems produce unwanted noise perceived by users, which affects their comfort. Engineers encounter several difficulties in carrying out experimental measurements when studying complex systems. To solve this problem, a solution was proposed for the manufacturers' benefit, allowing them to access the various identified measurement points, describe the systems' vibroacoustic behavior, whether coupled or decoupled, and share the work between several teams and reduce the time spent on measurements. This paper deals with the experimental study performed on an aircraft noise abatement isolator. The component-based transfer path analysis hybrid inverse method is developed to allow the work on the subsystems separately between several teams and characterize them on an external test bench outside real functioning conditions. The studied system consists of a mass coupled by a noise abatement isolator fixed in an aluminum plate backed by a concrete cavity. Several parameters are studied such as the number of transfer paths to be considered to see the effect of neglecting certain transfer paths, the effects of coupling versus decoupling of the connected substructures and the number of indicator points chosen and used in the inversion method. The results are compared to the direct method.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":"136 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135761899","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In tropical climate countries, the house structure with a vent hole is widely used. The vent hole has a structure that penetrates the house's outer wall, allowing fresh air from outside to enter the room. However, external traffic noise also enters the living spaces through the vents. A novel type of soundproof vent hole unit with both soundproofing and ventilation functions was proposed in previous work. An elliptical cavity was used for this unit, but it is difficult to manufacture an elliptical cavity with a high eccentricity; also, the installation and adjustment work are expected to be difficult. A rectangular cavity with an inlet and outlet in orthogonal planes fitted to the house walls is used in this study to provide soundproofing functionality to the vent hole. First, the generation mechanism of sound pressure components propagating inside the unit was theoretically elucidated using the three-dimensional wave equation. Second, to maximize soundproofing ability, methods for reducing the number of resonances and reducing the effect of higher-order sound pressure components are described.
{"title":"Improvement of a soundproofing vent hole","authors":"Nishimura Sohei, Nishimura Yuya, Tsukamoto Akifumi","doi":"10.3397/1/377119","DOIUrl":"https://doi.org/10.3397/1/377119","url":null,"abstract":"In tropical climate countries, the house structure with a vent hole is widely used. The vent hole has a structure that penetrates the house's outer wall, allowing fresh air from outside to enter the room. However, external traffic noise also enters the living spaces through the vents.\u0000 A novel type of soundproof vent hole unit with both soundproofing and ventilation functions was proposed in previous work. An elliptical cavity was used for this unit, but it is difficult to manufacture an elliptical cavity with a high eccentricity; also, the installation and adjustment work\u0000 are expected to be difficult. A rectangular cavity with an inlet and outlet in orthogonal planes fitted to the house walls is used in this study to provide soundproofing functionality to the vent hole. First, the generation mechanism of sound pressure components propagating inside the unit\u0000 was theoretically elucidated using the three-dimensional wave equation. Second, to maximize soundproofing ability, methods for reducing the number of resonances and reducing the effect of higher-order sound pressure components are described.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45276971","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abnormal vibration often occurs in the liquid oxygen kerosene transmission pipe- line of rocket engines, seriously threatening the safety of rocket engines. Improper handling will result in rocket launch failure and enormous economic losses. Therefore, the vibration of the transmission pipeline must be studied. In this paper, a three-dimensional high-pressure transmission pipeline model comprising a corrugated pipe, a multi-section bending pipe, and other auxiliary structures is established. Using the two-way fluid–solid coupling method, vibration analysis is performed on the pipeline under external pressure pulse excitation. The accuracy of the computation results is verified by a thermal test. Two vibration reduction strategies are presented and validated by simulation in accordance with the findings of the vibration study. The main conclusions are as follows: (1) At the same frequency, the amplitude distribution of vibration acceleration significantly correlates with the flow field pressure, indicating that fluid pressure fluctuation is the root cause of the abnormal vibration of the pipeline, and the vibration of the pipeline increases with the average pressure. (2) The time-average value and fluctuation amplitude of the larger stress and strain are mainly concentrated in the two supports, namely, the inside of the elbow and the bellows, which is different from the distribution of vibration acceleration. Such places are prone to structural failure and should be given attention. (3) The guide plate and the support enhancement method can reduce the vibration, but the support enhancement method has a better effect, reducing the vibration velocity and acceleration by 86.4% and 93%, respectively.
{"title":"Case study: Analysis and research on pipeline vibration of liquid oxygen kerosene of rocket engine and vibration reduction measures Measures","authors":"S. Yong, Gong Wu-qi","doi":"10.3397/1/377114","DOIUrl":"https://doi.org/10.3397/1/377114","url":null,"abstract":"Abnormal vibration often occurs in the liquid oxygen kerosene transmission pipe- line of rocket engines, seriously threatening the safety of rocket engines. Improper handling will result in rocket launch failure and enormous economic losses. Therefore, the vibration of the transmission\u0000 pipeline must be studied. In this paper, a three-dimensional high-pressure transmission pipeline model comprising a corrugated pipe, a multi-section bending pipe, and other auxiliary structures is established. Using the two-way fluid–solid coupling method, vibration analysis is performed\u0000 on the pipeline under external pressure pulse excitation. The accuracy of the computation results is verified by a thermal test. Two vibration reduction strategies are presented and validated by simulation in accordance with the findings of the vibration study. The main conclusions are as\u0000 follows: (1) At the same frequency, the amplitude distribution of vibration acceleration significantly correlates with the flow field pressure, indicating that fluid pressure fluctuation is the root cause of the abnormal vibration of the pipeline, and the vibration of the pipeline increases\u0000 with the average pressure. (2) The time-average value and fluctuation amplitude of the larger stress and strain are mainly concentrated in the two supports, namely, the inside of the elbow and the bellows, which is different from the distribution of vibration acceleration. Such places are\u0000 prone to structural failure and should be given attention. (3) The guide plate and the support enhancement method can reduce the vibration, but the support enhancement method has a better effect, reducing the vibration velocity and acceleration by 86.4% and 93%, respectively.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46461783","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Min-Hyeok Kim, Suk-Yoon Hong, Jee-hun Song, Beom-Jin Joe, Woen-Sug Choi
Fans generate tone noise and broadband noise. The first blade-passing frequency noise is a tone noise and is the most dominant; attaching a duct and a stator can reduce this noise. However, there has been no theoretical development in using structural characteristics to reduce the noise generated by ducted fans. In this study, noise predictions using Lighthill's equation and Green's function were performed to determine the optimal duct length for a ducted fan's noise reduction. New formulations for predicting the length were derived using a modal noise analysis. Noise sources were obtained from computational fluid dynamics data and wall pressure spectra. The formulations deduce a linear relationship between a duct's radius and length and can be used as a tool to indicate fan size at the design stage under space and weight constraints without high computational costs.
{"title":"Optimal duct length of ducted fans for minimizing first blade-passing frequency noise","authors":"Min-Hyeok Kim, Suk-Yoon Hong, Jee-hun Song, Beom-Jin Joe, Woen-Sug Choi","doi":"10.3397/1/377116","DOIUrl":"https://doi.org/10.3397/1/377116","url":null,"abstract":"Fans generate tone noise and broadband noise. The first blade-passing frequency noise is a tone noise and is the most dominant; attaching a duct and a stator can reduce this noise. However, there has been no theoretical development in using structural characteristics to reduce the noise\u0000 generated by ducted fans. In this study, noise predictions using Lighthill's equation and Green's function were performed to determine the optimal duct length for a ducted fan's noise reduction. New formulations for predicting the length were derived using a modal noise analysis. Noise sources\u0000 were obtained from computational fluid dynamics data and wall pressure spectra. The formulations deduce a linear relationship between a duct's radius and length and can be used as a tool to indicate fan size at the design stage under space and weight constraints without high computational\u0000 costs.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45054746","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An efficient exhaust muffler needs to satisfy the rather conflicting requirements of adequate insertion loss (IL) with limited back pressure, weight, size and cost. The unmuffled exhaust noise of an internal combustion engine peaks at the engine firing frequency and the first few harmonics thereof. Designing the muffler (a wide-band low pass acoustical filter) for such low frequencies is quite a challenge. Therefore, design of efficient mufflers has remained an art as well as science. During the last two decades or so, however, (a) multi-hole cross-flow perforates, (b) multiply connected perforated pipes and baffles, and (c) the double-tuned, grazing-flow concentric tube resonators have emerged as promising constituent elements. In this paper, elements (a) and (c) have been combined ingeniously to synthesize efficient muffler configuration for diesel generator (DG) sets as well as automotive engines. Relatively simpler lumped parameter approximation for perforates opening into cavities, electro-acoustic analogies, and the simple expansion chamber equivalence of the double-tuned concentric tube resonator have been used to develop a rational design methodology. A novel feature of this methodology is incorporation of the given back-pressure limit into the acoustic design process. The resulting muffler configurations are robust and can be scaled up (and down) easily for IL as well as back pressure.
{"title":"State of the art of rational design of efficient mufflers","authors":"M.L. Munjal, K.M. Kumar","doi":"10.3397/1/377115","DOIUrl":"https://doi.org/10.3397/1/377115","url":null,"abstract":"An efficient exhaust muffler needs to satisfy the rather conflicting requirements of adequate insertion loss (IL) with limited back pressure, weight, size and cost. The unmuffled exhaust noise of an internal combustion engine peaks at the engine firing frequency and the first few harmonics thereof. Designing the muffler (a wide-band low pass acoustical filter) for such low frequencies is quite a challenge. Therefore, design of efficient mufflers has remained an art as well as science. During the last two decades or so, however, (a) multi-hole cross-flow perforates, (b) multiply connected perforated pipes and baffles, and (c) the double-tuned, grazing-flow concentric tube resonators have emerged as promising constituent elements. In this paper, elements (a) and (c) have been combined ingeniously to synthesize efficient muffler configuration for diesel generator (DG) sets as well as automotive engines. Relatively simpler lumped parameter approximation for perforates opening into cavities, electro-acoustic analogies, and the simple expansion chamber equivalence of the double-tuned concentric tube resonator have been used to develop a rational design methodology. A novel feature of this methodology is incorporation of the given back-pressure limit into the acoustic design process. The resulting muffler configurations are robust and can be scaled up (and down) easily for IL as well as back pressure.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135345190","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Acoustic metamaterial attains uncommon material properties over natural material such as negative effective mass density, negative effective bulk modulus, or both. To start with, the present research demonstrates and establishes robust method to estimate and measure acoustic metamaterial properties of a Helmholtz resonator analytically using transfer matrix (TM) method and experimentally in detail. The proposed method extracts the reflection and transmission coefficients from corresponding TM to evaluate the effective acoustic metamaterial properties. For a single Helmholtz resonator, the effective bulk modulus has been observed negative; however, the effective density remains positive. In order to attain double negative material properties, the perforated panel (PP) and microperforated panel (MPP) have been introduced in parallel to resonator. The 1D electro-acoustic modeling has been carried out for all configurations to estimate effective properties analytically. Successively, the experiments have been conducted to measure the effective properties from acoustic metamaterial prospective. The analytical and experimental investigations on five different cases reveal that one can attain negative effective compressibility and effective density by cascading two PPs or MPPs with a finite duct. Moreover, by backing a Helmholtz resonator from both sides with two PPs or MPPs in parallel, one can attain double negative properties comparatively higher than earlier configuration in low-frequency zone in broadband. In total, eight different configurations have been investigated analytically and experimentally, where it has been demonstrated that the proposed compact model is more effective than a finite array of same Helmholtz resonators.
{"title":"Estimating effective acoustic properties of various configuration of perforated panels","authors":"J. Dandsena","doi":"10.3397/1/377118","DOIUrl":"https://doi.org/10.3397/1/377118","url":null,"abstract":"Acoustic metamaterial attains uncommon material properties over natural material such as negative effective mass density, negative effective bulk modulus, or both. To start with, the present research demonstrates and establishes robust method to estimate and measure acoustic metamaterial\u0000 properties of a Helmholtz resonator analytically using transfer matrix (TM) method and experimentally in detail. The proposed method extracts the reflection and transmission coefficients from corresponding TM to evaluate the effective acoustic metamaterial properties. For a single Helmholtz\u0000 resonator, the effective bulk modulus has been observed negative; however, the effective density remains positive. In order to attain double negative material properties, the perforated panel (PP) and microperforated panel (MPP) have been introduced in parallel to resonator. The 1D electro-acoustic\u0000 modeling has been carried out for all configurations to estimate effective properties analytically. Successively, the experiments have been conducted to measure the effective properties from acoustic metamaterial prospective. The analytical and experimental investigations on five different\u0000 cases reveal that one can attain negative effective compressibility and effective density by cascading two PPs or MPPs with a finite duct. Moreover, by backing a Helmholtz resonator from both sides with two PPs or MPPs in parallel, one can attain double negative properties comparatively higher\u0000 than earlier configuration in low-frequency zone in broadband. In total, eight different configurations have been investigated analytically and experimentally, where it has been demonstrated that the proposed compact model is more effective than a finite array of same Helmholtz resonators.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44725577","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper presents the development of an empirical noise reduction coefficient model for the prediction of low-density, less than 50 kg/m3, thin, less than 20 mm thick, fibrous materials using multiple linear regression. The purpose of this empirical model is to assist design engineers, working with thin and low-density materials, efficiently and effectively select the most appropriate material for the design. Therefore, several models were developed using software such as Statistical Analysis System. Thereafter, the models were compared using an internal and external data set. A selection metric was developed to assist in the objective selection of the best model. It was found that the log model performed the best overall and thus was selected as the model of choice.
{"title":"Development of an empirical model for the prediction of the noise reduction coefficient for thin and low-density fibrous materials","authors":"Regan Dunne, Dawood Desai, S. Heyns","doi":"10.3397/1/377117","DOIUrl":"https://doi.org/10.3397/1/377117","url":null,"abstract":"This paper presents the development of an empirical noise reduction coefficient model for the prediction of low-density, less than 50 kg/m3, thin, less than 20 mm thick, fibrous materials using multiple linear regression. The purpose of this empirical model is to assist design engineers,\u0000 working with thin and low-density materials, efficiently and effectively select the most appropriate material for the design. Therefore, several models were developed using software such as Statistical Analysis System. Thereafter, the models were compared using an internal and external data\u0000 set. A selection metric was developed to assist in the objective selection of the best model. It was found that the log model performed the best overall and thus was selected as the model of choice.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46671225","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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