R. F. Madvari, Mohammad Jafari, T. W. Hong, F. Laal, M. N. Sharak
Metal foams are interesting as sound absorbers because of their strength, low mass, high hardness, and damping. To foam fabrication more accurate and achieve higher sound absorption coefficient (SAC), the effective parameters should be optimized. In earlier study (DOI: 10.32604/sv.2021.09729), the parameters of porosity percent- age (Ω), pore size (D) and pore opening size (d) were optimized by the authors. In this study, we intend to investigate the effect of optimized Ω percentage, D size and d size on the SAC of aluminum foam in the frequency 0 to 8000 Hz with the thicknesses of 5, 10, 20, and 30 mm. The genetic algorithm was performed employing the Lu model, using MATLAB software. According to the results, the optimum values of Ω, D, and d at different frequencies and thicknesses are not constant. That is, at any given thickness and frequency, there are specific optimum amounts. This study provides a way to improve the SAC performance of porous metal materials for various and targeted applications.
{"title":"Effect of porosity, pore size, and pore-opening size optimized on the sound absorption coefficient of aluminum foam","authors":"R. F. Madvari, Mohammad Jafari, T. W. Hong, F. Laal, M. N. Sharak","doi":"10.3397/1/37718","DOIUrl":"https://doi.org/10.3397/1/37718","url":null,"abstract":"Metal foams are interesting as sound absorbers because of their strength, low mass, high hardness, and damping. To foam fabrication more accurate and achieve higher sound absorption coefficient (SAC), the effective parameters should be optimized. In earlier study (DOI: 10.32604/sv.2021.09729),\u0000 the parameters of porosity percent- age (Ω), pore size (D) and pore opening size (d) were optimized by the authors. In this study, we intend to investigate the effect of optimized Ω percentage, D size and d size on the SAC of aluminum foam in the frequency 0 to 8000 Hz with the thicknesses\u0000 of 5, 10, 20, and 30 mm. The genetic algorithm was performed employing the Lu model, using MATLAB software. According to the results, the optimum values of Ω, D, and d at different frequencies and thicknesses are not constant. That is, at any given thickness and frequency, there are specific\u0000 optimum amounts. This study provides a way to improve the SAC performance of porous metal materials for various and targeted applications.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47167486","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}
To study the damping effect of different track structures on the environmental vibration, field tests of train-induced vertical acceleration were performed on four types of track structures, namely, ordinary track (OT), medium vibration-damping fastener track (MVDFT), floating-ladder track (FLT) and steel-spring floating slab track (SSFST). The measurement points were set on the rails, track slabs, and tunnel walls. Eventually, the time domain, frequency domain, and one-third- octave frequency division vibration level were adopted to investigate the vibration characteristics of four track structures. The results were obtained as follows. (1) The root-mean-square acceleration values of the four track structures at different measurement points were analyzed in the time domain. Overall, the results could not effectively reflect the damping capacity of the vibration-reduction measures. (2) Based on the one-third octave frequency analysis, regarding 10À6 m/s2 as the decibel reference value, we found that three vibration-reduction measures' vertical vibration level of the tunnel wall was significantly lower than that of OT. Specifically, the damping effect of SSFST was the most obvious. The Z-weighted vibration levels of the three vibration-reduction measures on the tunnel wall have been reduced by 8.919, 11.745 and 13.744 dB, respectively. (3) According to the results of the vibration-transmission characteristics in the frequency domain, the main vibration-frequency regions of the four track structures at the track slab and tunnel wall were all in the range of 1 to 20,00 Hz. Concerning OT, MVDFT, FLT, and SSFST, the peak values of the vibration transmission from the rail to the tunnel wall sequentially decreased, and the damping effect sequentially increased. This paper compared the damping capacity of the above four track structures at 1 to 80 Hz according to ISO 2631-1. In addition, their more detailed vibration characteristics at 1 to 2000 Hz were also considered. It aims to provide a more comprehensive study for the application of subway vibration-reduction measures.
{"title":"Comparison and analysis of vibration characteristics of different subway tracks","authors":"Z. Zeng, Xiangdong Huang, Weidong Wang, Xinwei Luo, Hua-tuo Yin, Zhi-peng Wu","doi":"10.3397/1/377112","DOIUrl":"https://doi.org/10.3397/1/377112","url":null,"abstract":"To study the damping effect of different track structures on the environmental vibration, field tests of train-induced vertical acceleration were performed on four types of track structures, namely, ordinary track (OT), medium vibration-damping fastener track (MVDFT), floating-ladder\u0000 track (FLT) and steel-spring floating slab track (SSFST). The measurement points were set on the rails, track slabs, and tunnel walls. Eventually, the time domain, frequency domain, and one-third- octave frequency division vibration level were adopted to investigate the vibration characteristics\u0000 of four track structures. The results were obtained as follows. (1) The root-mean-square acceleration values of the four track structures at different measurement points were analyzed in the time domain. Overall, the results could not effectively reflect the damping capacity of the vibration-reduction\u0000 measures. (2) Based on the one-third octave frequency analysis, regarding 10À6 m/s2 as the decibel reference value, we found that three vibration-reduction measures' vertical vibration level of the tunnel wall was significantly lower than that of OT. Specifically, the damping effect\u0000 of SSFST was the most obvious. The Z-weighted vibration levels of the three vibration-reduction measures on the tunnel wall have been reduced by 8.919, 11.745 and 13.744 dB, respectively. (3) According to the results of the vibration-transmission characteristics in the frequency domain, the\u0000 main vibration-frequency regions of the four track structures at the track slab and tunnel wall were all in the range of 1 to 20,00 Hz. Concerning OT, MVDFT, FLT, and SSFST, the peak values of the vibration transmission from the rail to the tunnel wall sequentially decreased, and the damping\u0000 effect sequentially increased. This paper compared the damping capacity of the above four track structures at 1 to 80 Hz according to ISO 2631-1. In addition, their more detailed vibration characteristics at 1 to 2000 Hz were also considered. It aims to provide a more comprehensive study for\u0000 the application of subway vibration-reduction measures.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":"1 1","pages":""},"PeriodicalIF":0.4,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42850424","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}
Z. Laly, N. Atalla, R. Panneton, S. Ghinet, Chris M. Mechefske
The propagation of acoustic waves in porous materials attenuates with distance. When the thickness of the porous material is equal to the acoustic penetration depth, or critical depth, the sound absorption coefficient reaches an asymptotic value so that any additional thickness of the porous layer provides no significant increase of the sound absorption. To overcome the limitations of the critical depth, a design of sound absorbing material containing periodic holes with decreasing profile diameter is proposed in this paper. The finite element method is used to demonstrate the improved sound absorption over a large frequency band. An extraordinary improvement of the sound absorption coefficient using a periodic conical hole is demonstrated where the critical depth of the porous material is eliminated. The results using the finite element method are compared with theoretical results from a transfer matrix method using a double porosity model, and a good agreement is obtained. A parametric analysis is presented using finite element simulations to illustrate the effects of the different parameters of the decreasing hole profile diameter on the sound absorption coefficient. Different hole shapes with decreasing profile diameters distributed periodically inside the porous layer are compared, and the results show good acoustic performance. The proposed sound absorbing material is applied in a rectangular room as anechoic termination. The result of the reflection coefficient obtained by a mirror source method is close to zero over a large frequency band. This illustrates good sound attenuation of the proposed design.
{"title":"Finite element analysis of sound absorbing material with periodic decreasing hole profiles","authors":"Z. Laly, N. Atalla, R. Panneton, S. Ghinet, Chris M. Mechefske","doi":"10.3397/1/37717","DOIUrl":"https://doi.org/10.3397/1/37717","url":null,"abstract":"The propagation of acoustic waves in porous materials attenuates with distance. When the thickness of the porous material is equal to the acoustic penetration depth, or critical depth, the sound absorption coefficient reaches an asymptotic value so that any additional thickness of the\u0000 porous layer provides no significant increase of the sound absorption. To overcome the limitations of the critical depth, a design of sound absorbing material containing periodic holes with decreasing profile diameter is proposed in this paper. The finite element method is used to demonstrate\u0000 the improved sound absorption over a large frequency band. An extraordinary improvement of the sound absorption coefficient using a periodic conical hole is demonstrated where the critical depth of the porous material is eliminated. The results using the finite element method are compared\u0000 with theoretical results from a transfer matrix method using a double porosity model, and a good agreement is obtained. A parametric analysis is presented using finite element simulations to illustrate the effects of the different parameters of the decreasing hole profile diameter on the sound\u0000 absorption coefficient. Different hole shapes with decreasing profile diameters distributed periodically inside the porous layer are compared, and the results show good acoustic performance. The proposed sound absorbing material is applied in a rectangular room as anechoic termination. The\u0000 result of the reflection coefficient obtained by a mirror source method is close to zero over a large frequency band. This illustrates good sound attenuation of the proposed design.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43591679","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}
The aluminum square tube is one of the ceiling materials that have been produced in recent years. It has become the most popular product in the decoration market because its lines are bright and clean with distinct layers, reflecting the simple modern style, and it is easy to install and dismantle. However, the aluminum square tube used in the market is mostly a single aluminum panel structure, mainly used for decoration, without sound absorption and noise reduction. In order to improve the sound absorption properties of the aluminum square tube, a microporous aluminum square tube space absorber is proposed. The reverberation chamber method is used to investigate the sound absorption properties of the microporous aluminum square tube. The results show that the sound absorption performance of the aluminum square tube can be greatly improved by the formation of micropores on it. The sound absorption performance of the aluminum square tube perforated on three sides is better than that of the aluminum square tube perforated on only two sides. In the case of perforation on only two sides, with the increase in the height of the perforated surface, the peak value of sound absorption is gradually increased. In addition, the sound absorption peak gradually shifts to the low-frequency direction as the distance between the perforated surfaces increases. The reasonable design of structural parameters of microporous aluminum square tube can make it have beautiful decorative effect and good sound absorbing effect.
{"title":"Experimental study on sound absorption performance of microporous aluminum square tube space absorber","authors":"Xiao-Ling Gai, Zenong Cai, Xian-hui Li, Wencheng Hu, Tuo Xing, Xiwen Guan, Jiabin Zhao","doi":"10.3397/1/37719","DOIUrl":"https://doi.org/10.3397/1/37719","url":null,"abstract":"The aluminum square tube is one of the ceiling materials that have been produced in recent years. It has become the most popular product in the decoration market because its lines are bright and clean with distinct layers, reflecting the simple modern style, and it is easy to install\u0000 and dismantle. However, the aluminum square tube used in the market is mostly a single aluminum panel structure, mainly used for decoration, without sound absorption and noise reduction. In order to improve the sound absorption properties of the aluminum square tube, a microporous aluminum\u0000 square tube space absorber is proposed. The reverberation chamber method is used to investigate the sound absorption properties of the microporous aluminum square tube. The results show that the sound absorption performance of the aluminum square tube can be greatly improved by the formation\u0000 of micropores on it. The sound absorption performance of the aluminum square tube perforated on three sides is better than that of the aluminum square tube perforated on only two sides. In the case of perforation on only two sides, with the increase in the height of the perforated surface,\u0000 the peak value of sound absorption is gradually increased. In addition, the sound absorption peak gradually shifts to the low-frequency direction as the distance between the perforated surfaces increases. The reasonable design of structural parameters of microporous aluminum square tube can\u0000 make it have beautiful decorative effect and good sound absorbing effect.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48416041","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}
The automotive turbocharger compressor in the present experimental study features a ported shroud casing treatment, which is known to elevate tonal noise at the blade-pass frequency (BPF) while reducing broadband whoosh noise and providing higher boost pressures at low mass flow rates. The high operating rotational speeds of such modern turbocharger compressors push the BPF to ranges where acoustic wave propagation is multi-dimensional within the compressor ducting. Simultaneously propagating acoustic modes at the BPF result in strong circumferential and axial variation of in-duct sound pressure levels. This poses a challenge for acoustic characterization and comparison of different hardware since typical measurement techniques do not consider the sensitivity of acoustic pressure to the measurement location. The current work utilizes a steady-flow turbocharger gas stand with a unique rotating compressor inlet duct fitted with multiple wall-mounted dynamic pressure transducers capable of performing a modal decomposition of the acoustic field. The decomposition is done using time-resolved acoustic pressure measurements from different orientations of the rotating inlet duct during steady compressor operation. The resulting modal amplitudes are then used to determine the sound power level, a quantity that is independent of the acoustic pressure measurement locations. Therefore, in addition to revealing the modal content of noise at the compressor inlet, the rotating inlet duct experimental setup better characterizes the acoustic field with sound power levels across the operating flow range at various compressor rotational speeds.
{"title":"An experimental modal decomposition method to compute sound power of multi-dimensional acoustic waves from turbocharger compressors","authors":"P. Sriganesh, A. Selamet","doi":"10.3397/1/377111","DOIUrl":"https://doi.org/10.3397/1/377111","url":null,"abstract":"The automotive turbocharger compressor in the present experimental study features a ported shroud casing treatment, which is known to elevate tonal noise at the blade-pass frequency (BPF) while reducing broadband whoosh noise and providing higher boost pressures at low mass flow rates.\u0000 The high operating rotational speeds of such modern turbocharger compressors push the BPF to ranges where acoustic wave propagation is multi-dimensional within the compressor ducting. Simultaneously propagating acoustic modes at the BPF result in strong circumferential and axial variation\u0000 of in-duct sound pressure levels. This poses a challenge for acoustic characterization and comparison of different hardware since typical measurement techniques do not consider the sensitivity of acoustic pressure to the measurement location. The current work utilizes a steady-flow turbocharger\u0000 gas stand with a unique rotating compressor inlet duct fitted with multiple wall-mounted dynamic pressure transducers capable of performing a modal decomposition of the acoustic field. The decomposition is done using time-resolved acoustic pressure measurements from different orientations\u0000 of the rotating inlet duct during steady compressor operation. The resulting modal amplitudes are then used to determine the sound power level, a quantity that is independent of the acoustic pressure measurement locations. Therefore, in addition to revealing the modal content of noise at the\u0000 compressor inlet, the rotating inlet duct experimental setup better characterizes the acoustic field with sound power levels across the operating flow range at various compressor rotational speeds.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49329072","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}
Levent Bozcu, İ. E. Söğütlü, Sinem Öztürk, H. Erol
In this study, a control system actively canceling the noise will be developed through a model-based algorithm to reduce the noise generated in the room on individuals in an environment as much as possible. The model-based design approach is preferred because it is convenient for optimization and can be applied much more effortlessly than real experiments; it is applied using the finite difference method. The model developed within this scope has been validated by comparing it with the acoustic test data performed in an empty room. The positioning of loudspeakers was accomplished through a heuristic search algorithm to obtain the highest local cancellation of noise originating in the acoustic cavity from any position(s) in the targeted area. The feedforward adaptive control system chosen to drive the control loudspeakers is implemented using the least mean squares algorithm. The efficiency of the designed system under different noise conditions was examined, and two of them were included in the study.
{"title":"On optimum speaker placement with a model-based approach for indoor local active noise control applications","authors":"Levent Bozcu, İ. E. Söğütlü, Sinem Öztürk, H. Erol","doi":"10.3397/1/377110","DOIUrl":"https://doi.org/10.3397/1/377110","url":null,"abstract":"In this study, a control system actively canceling the noise will be developed through a model-based algorithm to reduce the noise generated in the room on individuals in an environment as much as possible. The model-based design approach is preferred because it is convenient for optimization\u0000 and can be applied much more effortlessly than real experiments; it is applied using the finite difference method. The model developed within this scope has been validated by comparing it with the acoustic test data performed in an empty room. The positioning of loudspeakers was accomplished\u0000 through a heuristic search algorithm to obtain the highest local cancellation of noise originating in the acoustic cavity from any position(s) in the targeted area. The feedforward adaptive control system chosen to drive the control loudspeakers is implemented using the least mean squares\u0000 algorithm. The efficiency of the designed system under different noise conditions was examined, and two of them were included in the study.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44255404","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}
Sunit Girdhar, A. Barnard, J. Blough, John Loverde, Wayland Dong
The current ASTM and International Standards Organization (ISO) standard im- pact test method for floor-ceiling assemblies does not require the test engineer to measure the input force during the impact. A standard tapping machine or a standard impact ball is used for these tests, but these input sources usually do not have any provision to measure the input force. In this work, the input force of these impact methods was measured on seven different assemblies, and a modal hammer was used as a “control” source. The input force and average floor impedance were measured and compared to each other. The peak input force levels due to the tapping machine vary by approximately 38 dB from one floor to the other, and the frequency excitation bandwidth varies widely based on the type of floor construction. This shows that there is a need to measure the input force and scale the output sound quantity with the input force to get a frequency response function (FRF)-like quantity to compare different floor-ceiling assemblies. For the impact ball, the variation in low-frequency input force levels is almost non-existent, but the impact ball has a poor measurement signal-to-noise ratio above 80 Hz one-third octave band. The impedance measured using the impact ball matches closely with the control impedance measured using the modal hammer.
{"title":"Input force and floor impedance measurement for the standard tapping machine and the standard impact ball","authors":"Sunit Girdhar, A. Barnard, J. Blough, John Loverde, Wayland Dong","doi":"10.3397/1/37716","DOIUrl":"https://doi.org/10.3397/1/37716","url":null,"abstract":"The current ASTM and International Standards Organization (ISO) standard im- pact test method for floor-ceiling assemblies does not require the test engineer to measure the input force during the impact. A standard tapping machine or a standard impact ball is used for these tests, but\u0000 these input sources usually do not have any provision to measure the input force. In this work, the input force of these impact methods was measured on seven different assemblies, and a modal hammer was used as a “control” source. The input force and average floor impedance were\u0000 measured and compared to each other. The peak input force levels due to the tapping machine vary by approximately 38 dB from one floor to the other, and the frequency excitation bandwidth varies widely based on the type of floor construction. This shows that there is a need to measure the\u0000 input force and scale the output sound quantity with the input force to get a frequency response function (FRF)-like quantity to compare different floor-ceiling assemblies. For the impact ball, the variation in low-frequency input force levels is almost non-existent, but the impact ball has\u0000 a poor measurement signal-to-noise ratio above 80 Hz one-third octave band. The impedance measured using the impact ball matches closely with the control impedance measured using the modal hammer.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45192662","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}
Micro-vibration is an important factor that influences the imager orientation accu- racy and even deteriorates the quality of image of high-resolution satellite. To eliminate the influences of micro-vibration, a passive micro-vibration isolation method is proposed for reaction wheels (RWs) of satellite. At the same time, the launch environment is fully considered in the design of isolation system to guarantee the safety of both RWs. The isolation efficiency and orientation stability experiment results show that, without isolators, the peak value of the torque output reaches more than 10 Nm that is sharply depressed with isolation system operating mode. Without isolators, four clear peak values located at 10 Hz, 41 Hz, 47 Hz, 83 Hz are found in the orientation oscillation of RW. The random vibration experiments show that the maximal acceleration output 34.61 g is much lower than the RW design value 49 g which guarantees the safety of RW under harsh launch environment. The isolating efficiency is higher than 75% which is suitable for the requirement of the imager on-board the SDLT-1 satellite.
{"title":"Design and validation of micro-vibration isolator for reaction wheels in consideration of launch environment of satellite","authors":"Jie Huang, Z.F. Yu","doi":"10.3397/1/37715","DOIUrl":"https://doi.org/10.3397/1/37715","url":null,"abstract":"Micro-vibration is an important factor that influences the imager orientation accu- racy and even deteriorates the quality of image of high-resolution satellite. To eliminate the influences of micro-vibration, a passive micro-vibration isolation method is proposed for reaction wheels\u0000 (RWs) of satellite. At the same time, the launch environment is fully considered in the design of isolation system to guarantee the safety of both RWs. The isolation efficiency and orientation stability experiment results show that, without isolators, the peak value of the torque output reaches\u0000 more than 10 Nm that is sharply depressed with isolation system operating mode. Without isolators, four clear peak values located at 10 Hz, 41 Hz, 47 Hz, 83 Hz are found in the orientation oscillation of RW. The random vibration experiments show that the maximal acceleration output 34.61 g\u0000 is much lower than the RW design value 49 g which guarantees the safety of RW under harsh launch environment. The isolating efficiency is higher than 75% which is suitable for the requirement of the imager on-board the SDLT-1 satellite.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47953276","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}
Aircraft noise is generally regarded as the most annoying source of environmental noise and is the most common source of complaints raised by residents living in the vicinity of airports. Many different types of abatement measures can be utilized by airports to reduce the noise impact, but the manner of their implementation can vary between airports. To assess how noise control strategies are implemented across the United States (US), a national survey of noise abatement strategies was conducted. The paper provides a summary of this survey and reports the noise control approaches at 42 different airports across the US. The survey considered general aspects of noise control, as well as specific questions related to noise abatement procedures, noise limits and curfews. Participants were also asked their opinion on the impact of the International Civil Aviation Organization (ICAO) Balanced Approach, which is the ICAO recommended framework to address aircraft noise. Although just a snapshot of activities across the US is presented, results indicate that a wide array of noise abatement procedures is being implemented. Results also suggest that the ICAO Balanced Approach has yet to be fully embraced in the US, with a large proportion of respondents reporting that they are not familiar with this approach.
{"title":"Survey of aircraft noise abatement strategies in the US","authors":"E. King, Paul E. Slaboch","doi":"10.3397/1/37714","DOIUrl":"https://doi.org/10.3397/1/37714","url":null,"abstract":"Aircraft noise is generally regarded as the most annoying source of environmental noise and is the most common source of complaints raised by residents living in the vicinity of airports. Many different types of abatement measures can be utilized by airports to reduce the noise impact,\u0000 but the manner of their implementation can vary between airports. To assess how noise control strategies are implemented across the United States (US), a national survey of noise abatement strategies was conducted. The paper provides a summary of this survey and reports the noise control approaches\u0000 at 42 different airports across the US. The survey considered general aspects of noise control, as well as specific questions related to noise abatement procedures, noise limits and curfews. Participants were also asked their opinion on the impact of the International Civil Aviation Organization\u0000 (ICAO) Balanced Approach, which is the ICAO recommended framework to address aircraft noise. Although just a snapshot of activities across the US is presented, results indicate that a wide array of noise abatement procedures is being implemented. Results also suggest that the ICAO Balanced\u0000 Approach has yet to be fully embraced in the US, with a large proportion of respondents reporting that they are not familiar with this approach.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43171019","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}
The contribution analysis of various automobile noise sources to the interior noise is important, enabling to design an automobile with a low interior noise level. However, it is difficult to experimentally analyze the contribution of physically meaningful noise sources to the interior noise using the state-of-the-art contribution analysis method, for example, based on the transmissibility matrix method and the singular value decomposition (SVD), since the source strengths decomposed by using the SVD procedure are difficult to be associated with physical sources. Here, it is proposed to decompose an interior noise auto-spectrum into multiple auto-spectra, each represents the contribution of a physically meaningful noise source to the interior noise, by using the LDL decomposition. Through an experiment with the three speakers driven by three independent, filtered random noise signals, it was shown that the measured noise spectrum could be successfully decomposed into three contributions, each associated with noise radiated from only one speaker. Then, an automobile instrumented with 64 exterior and 4 interior microphones was tested on a highway at the speeds of 65 miles per hour (mph) and 80 mph. The contribution results obtained by processing the measured microphone signals indicated the highest contributions of the aeroacoustic sources on the windows and the hood to the interior noise.
{"title":"Experimental contribution analysis of external noise components to interior noise of an automobileExperimental contribution analysis of external noise components to interior noise of an automobile","authors":"Seongil Hwang, Myunghan Lee, K. Ih, Yong-Joe Kim","doi":"10.3397/1/37712","DOIUrl":"https://doi.org/10.3397/1/37712","url":null,"abstract":"The contribution analysis of various automobile noise sources to the interior noise is important, enabling to design an automobile with a low interior noise level. However, it is difficult to experimentally analyze the contribution of physically meaningful noise sources to the interior\u0000 noise using the state-of-the-art contribution analysis method, for example, based on the transmissibility matrix method and the singular value decomposition (SVD), since the source strengths decomposed by using the SVD procedure are difficult to be associated with physical sources. Here, it\u0000 is proposed to decompose an interior noise auto-spectrum into multiple auto-spectra, each represents the contribution of a physically meaningful noise source to the interior noise, by using the LDL decomposition. Through an experiment with the three speakers driven by three independent, filtered\u0000 random noise signals, it was shown that the measured noise spectrum could be successfully decomposed into three contributions, each associated with noise radiated from only one speaker. Then, an automobile instrumented with 64 exterior and 4 interior microphones was tested on a highway at\u0000 the speeds of 65 miles per hour (mph) and 80 mph. The contribution results obtained by processing the measured microphone signals indicated the highest contributions of the aeroacoustic sources on the windows and the hood to the interior noise.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48956032","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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