{"title":"Comparative Study of the Propagation of Jet Noise in Static and Flow Environments","authors":"Wen Zhao, Dongxing Mao, Zaixiu Jiang","doi":"10.32604/SV.2019.04368","DOIUrl":"https://doi.org/10.32604/SV.2019.04368","url":null,"abstract":"","PeriodicalId":49496,"journal":{"name":"Sound and Vibration","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81525400","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mining aeroengine operational data and developing fault diagnosis models for aeroengines are to avoid running aeroengines under undesired conditions. Because of the complexity of working environment and faults of aeroengines, it is unavoidable that the monitored parameters vary widely and possess larger noise levels. This paper reports the extrapolation of a diagnosis model for 20 gas path faults of a double-spool turbofan civil aeroengine. By applying support vector machine (SVM) algorithm together with genetic algorithm (GA), the fault diagnosis model is obtained from the training set that was based on the deviations of the monitored parameters superimposed with the noise level of 10%. The SVM model (C = 24.7034; γ = 179.835) was extrapolated for the samples whose noise levels were larger than 10%. The accuracies of extrapolation for samples with the noise levels of 20% and 30% are 97% and 94%, respectively. Compared with the models reported on the same faults, the extrapolation results of the GASVM model are accurate.
{"title":"Extrapolation for Aeroengine Gas Path Faults with SVM Bases on Genetic Algorithm","authors":"Yixiong Yu","doi":"10.32604/sv.2019.07887","DOIUrl":"https://doi.org/10.32604/sv.2019.07887","url":null,"abstract":"Mining aeroengine operational data and developing fault diagnosis models for aeroengines are to avoid running aeroengines under undesired conditions. Because of the complexity of working environment and faults of aeroengines, it is unavoidable that the monitored parameters vary widely and possess larger noise levels. This paper reports the extrapolation of a diagnosis model for 20 gas path faults of a double-spool turbofan civil aeroengine. By applying support vector machine (SVM) algorithm together with genetic algorithm (GA), the fault diagnosis model is obtained from the training set that was based on the deviations of the monitored parameters superimposed with the noise level of 10%. The SVM model (C = 24.7034; γ = 179.835) was extrapolated for the samples whose noise levels were larger than 10%. The accuracies of extrapolation for samples with the noise levels of 20% and 30% are 97% and 94%, respectively. Compared with the models reported on the same faults, the extrapolation results of the GASVM model are accurate.","PeriodicalId":49496,"journal":{"name":"Sound and Vibration","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85875858","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dry-Type Cast Resin Distribution Transformers (CRT) is the secondgeneration of air-cooled distribution transformers where oil is replaced by resin for electrical insulation. CRT transformers may installed indoor adjacent to or near residential areas since they are clean and safe comparing to the conventional transformers. But, as it is obvious, noise discrepancy is intrinsically accompanied with all types of transformers and is inevitable for CRT transformers too. Minimization of noise level caused by such these transformers has biological and ergonomic importance. As it is known the core of transformers is the main source of the noise generation. In this paper, experimental and numerical investigation is implemented for a large number of fabricated CRT transformers in IT Co (Iran Transfo Company) to evaluate the effective geometrical parameters of the core on the overall sound level of transformers. Noise Level of each sample is measured according to criteria of IEC60651 and is reported in units of Decibel (dB). Numerical simulation is done using noncommercial version of ANSYS Workbench software to extract first six natural frequencies and mode shapes of CRT cores which is reported in units of Hz. Three novel non-dimensional variables for geometry of the transformer core are introduced. Both experimental and numerical results show approximately similar response to these variables. Correlation between natural frequencies and noise level is evaluated statistically. Pearson factor shows that there is a robust conjunction between first two natural frequencies and noise level of CRTs. Results show that noise level decreases as the two first natural frequencies increases and vice versa, noise level increases as the two natural frequencies of the core decreases. Finally the noise level decomposed to two parts.
{"title":"Experimental and Numerical Study of the Key Non-Dimensional Geometrical Parameters on the Noise Level of Dry-Type Cast Resin Transformers","authors":"Mahdi Soltanmohammadi, Vahid Monfare","doi":"10.32604/sv.2019.05811","DOIUrl":"https://doi.org/10.32604/sv.2019.05811","url":null,"abstract":"Dry-Type Cast Resin Distribution Transformers (CRT) is the secondgeneration of air-cooled distribution transformers where oil is replaced by resin for electrical insulation. CRT transformers may installed indoor adjacent to or near residential areas since they are clean and safe comparing to the conventional transformers. But, as it is obvious, noise discrepancy is intrinsically accompanied with all types of transformers and is inevitable for CRT transformers too. Minimization of noise level caused by such these transformers has biological and ergonomic importance. As it is known the core of transformers is the main source of the noise generation. In this paper, experimental and numerical investigation is implemented for a large number of fabricated CRT transformers in IT Co (Iran Transfo Company) to evaluate the effective geometrical parameters of the core on the overall sound level of transformers. Noise Level of each sample is measured according to criteria of IEC60651 and is reported in units of Decibel (dB). Numerical simulation is done using noncommercial version of ANSYS Workbench software to extract first six natural frequencies and mode shapes of CRT cores which is reported in units of Hz. Three novel non-dimensional variables for geometry of the transformer core are introduced. Both experimental and numerical results show approximately similar response to these variables. Correlation between natural frequencies and noise level is evaluated statistically. Pearson factor shows that there is a robust conjunction between first two natural frequencies and noise level of CRTs. Results show that noise level decreases as the two first natural frequencies increases and vice versa, noise level increases as the two natural frequencies of the core decreases. Finally the noise level decomposed to two parts.","PeriodicalId":49496,"journal":{"name":"Sound and Vibration","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73023502","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, we present our report on the forced vibration of a bilayered plate-strip with initial stress resting on a rigid foundation induced by a time-harmonic force. The investigation is carried out according to the piecewise homogeneous body model with utilizing the three-dimensional linearized theory of elastic waves in initially stressed bodies (TLTEWISB). The materials of the body are chosen to be linearly elastic, homogeneous, and isotropic. The interface between the layers is assumed to be imperfect, and is simulated by the springlayer model. A similar degree of imperfection on the interface is realized in the normal and tangential directions. The mathematical model for the problem under consideration is designed, and the system of the equations of motion is approximately solved by employing the finite element method (FEM). The numerical results explaining the influence of the parameter that characterizes the degree of corresponding imperfectness on the dynamic response of the plate-strip are presented. In particular, we demonstrate that the distributions of the normal stress become flat, as the normal-spring parameter increases.
{"title":"A Spring-Layer Model for a Bi-Layered Plate-Strip with Initial Stress Through Imperfect Contact Interface","authors":"Ahmet Daşdemir","doi":"10.32604/sv.2019.04087","DOIUrl":"https://doi.org/10.32604/sv.2019.04087","url":null,"abstract":"In this paper, we present our report on the forced vibration of a bilayered plate-strip with initial stress resting on a rigid foundation induced by a time-harmonic force. The investigation is carried out according to the piecewise homogeneous body model with utilizing the three-dimensional linearized theory of elastic waves in initially stressed bodies (TLTEWISB). The materials of the body are chosen to be linearly elastic, homogeneous, and isotropic. The interface between the layers is assumed to be imperfect, and is simulated by the springlayer model. A similar degree of imperfection on the interface is realized in the normal and tangential directions. The mathematical model for the problem under consideration is designed, and the system of the equations of motion is approximately solved by employing the finite element method (FEM). The numerical results explaining the influence of the parameter that characterizes the degree of corresponding imperfectness on the dynamic response of the plate-strip are presented. In particular, we demonstrate that the distributions of the normal stress become flat, as the normal-spring parameter increases.","PeriodicalId":49496,"journal":{"name":"Sound and Vibration","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81192998","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Longitudinal Vibration Analysis of Elastically Coupled Nanorods System with General Boundary Supports","authors":"Deshui Xu, J. Du, Yuhao Zhao","doi":"10.32604/SV.2019.04033","DOIUrl":"https://doi.org/10.32604/SV.2019.04033","url":null,"abstract":"","PeriodicalId":49496,"journal":{"name":"Sound and Vibration","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83451346","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Mohanty, A. Adarsh, P. Dash, K. Parida, P. Pradhan
Condition monitoring is implementation of the advanced diagnostic techniques to reduce downtime and to increase the efficiency and reliability. The research is for determining the usage of advanced techniques like Vibration analysis, Oil analysis and Thermography to diagnose ensuing problems of the Plant and Machinery at an early stage and plan to take corrective and preventive actions to eliminate the forthcoming breakdown and enhancing the reliability of the system. Nowadays, the most of the industries have adopted the condition monitoring techniques as a part of support system to the basic maintenance strategies. Major condition monitoring technique they follow is Vibration Spectrum Analysis, which can detect faults at a very early stage. However implementation of other techniques like Oil analysis or Ferrography, Thermography etc. can further enhance the data interpretation as they would detect the source of abnormality at much early stage thus providing us with a longer lead time to plan and take the corrective actions. In Large Captive Power Plants and Aluminium Smelters, Integrated Condition Monitoring techniques play an important role as stoppage of primary system and its auxiliaries (boiler, steam turbine, generator, coal and ash handling plants etc.) results into the stoppage of the entire plant, which in turn leads to loss of productivity. From economical and operational point of view, it is desirable to ensure optimum level of system availability.
{"title":"Integrated Condition Monitoring of Large Captive Power Plants and Aluminum Smelters","authors":"J. Mohanty, A. Adarsh, P. Dash, K. Parida, P. Pradhan","doi":"10.32604/sv.2019.07737","DOIUrl":"https://doi.org/10.32604/sv.2019.07737","url":null,"abstract":"Condition monitoring is implementation of the advanced diagnostic techniques to reduce downtime and to increase the efficiency and reliability. The research is for determining the usage of advanced techniques like Vibration analysis, Oil analysis and Thermography to diagnose ensuing problems of the Plant and Machinery at an early stage and plan to take corrective and preventive actions to eliminate the forthcoming breakdown and enhancing the reliability of the system. Nowadays, the most of the industries have adopted the condition monitoring techniques as a part of support system to the basic maintenance strategies. Major condition monitoring technique they follow is Vibration Spectrum Analysis, which can detect faults at a very early stage. However implementation of other techniques like Oil analysis or Ferrography, Thermography etc. can further enhance the data interpretation as they would detect the source of abnormality at much early stage thus providing us with a longer lead time to plan and take the corrective actions. In Large Captive Power Plants and Aluminium Smelters, Integrated Condition Monitoring techniques play an important role as stoppage of primary system and its auxiliaries (boiler, steam turbine, generator, coal and ash handling plants etc.) results into the stoppage of the entire plant, which in turn leads to loss of productivity. From economical and operational point of view, it is desirable to ensure optimum level of system availability.","PeriodicalId":49496,"journal":{"name":"Sound and Vibration","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83154485","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Li Li, Xiaopeng Fan, KechengWu, Zhuanglei Zou, Yongyan Zhou, Dianhai Zhang, Z. Ren, Yanli Zhang
{"title":"Investigation on Noise Pollution Comprehensive Treatment of Distribution Transformer in Living Area","authors":"Li Li, Xiaopeng Fan, KechengWu, Zhuanglei Zou, Yongyan Zhou, Dianhai Zhang, Z. Ren, Yanli Zhang","doi":"10.32604/sv.2019.05252","DOIUrl":"https://doi.org/10.32604/sv.2019.05252","url":null,"abstract":"","PeriodicalId":49496,"journal":{"name":"Sound and Vibration","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73038545","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tim Chen, W. Marriott, A. Nicholson, Mars Kmieckowiak, J. Chen
{"title":"Corrections Notice to: Evolved Algorithm and Vibration Stability for Nonlinear Disturbed Security Systems","authors":"Tim Chen, W. Marriott, A. Nicholson, Mars Kmieckowiak, J. Chen","doi":"10.32604/sv.2019.00308","DOIUrl":"https://doi.org/10.32604/sv.2019.00308","url":null,"abstract":"","PeriodicalId":49496,"journal":{"name":"Sound and Vibration","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76843705","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
One of the practical approaches in identifying structures is the nonlinear resonant decay method which identifies a non-linear dynamic system utilizing a model based on linear modal space containing the underlying linear system and a small number of extra terms that exhibit the non-linear effects. In this paper, the method is illustrated in a simulated system and an experimental structure. The main objective of the non-linear resonant decay method is to identify the non-linear dynamic systems based on the use of a multi-shaker excitation using appropriated excitation which is obtained from the force appropriation approach. The experimental application of the method is indicated to provide suitable estimates of modal parameters for the identification of nonlinear models of structures.
{"title":"Experimental and Numerical Study of Structural Identification Using Non-Linear Resonant Decay Method","authors":"M. Sarmast, H. Ghafari, J. Wright","doi":"10.32604/sv.2019.04193","DOIUrl":"https://doi.org/10.32604/sv.2019.04193","url":null,"abstract":"One of the practical approaches in identifying structures is the nonlinear resonant decay method which identifies a non-linear dynamic system utilizing a model based on linear modal space containing the underlying linear system and a small number of extra terms that exhibit the non-linear effects. In this paper, the method is illustrated in a simulated system and an experimental structure. The main objective of the non-linear resonant decay method is to identify the non-linear dynamic systems based on the use of a multi-shaker excitation using appropriated excitation which is obtained from the force appropriation approach. The experimental application of the method is indicated to provide suitable estimates of modal parameters for the identification of nonlinear models of structures.","PeriodicalId":49496,"journal":{"name":"Sound and Vibration","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87009768","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Haiming Mai, Bo-sun Xie, Jianliang Jiang, D. Rao, Yang Liu
Ambisonics is a series of flexible spatial sound reproduction systems based on spatial harmonics decomposition of sound field. Traditional horizontal and spatial Ambisonics reconstruct horizontal and spatial sound field with certain order of spatial harmonics, respectively. Both the Shannon-Nyquist spatial sampling frequency limit for accurately reconstructing sound field and the complexity of system increase with the increasing order of Ambisonics. Based on the fact that the horizontal localization resolution of human hearing is higher than vertical resolution, mixed-order Ambisonics (MOA) reconstructs horizontal sound field with higher order spatial harmonics, while reconstructs vertical sound field with lower order spatial harmonics, and thereby reaches a compromise between the perceptual performance and the complexity of system. For a given order horizontal Ambisoncis or MOA reproduction, the number of horizontal loudspeakers is flexible, providing that it exceeds some low limit. By using Moore’s revised loudness model, the present work analyzes the influence of the number of horizontal loudspeakers on timbre both in horizontal Ambisonics and MOA reproduction. The binaural loudness level spectra (BLLS) of Ambisoncis reproduction are calculated and then compared with those of target sound field. The results indicate that below the Shannon-Nyquist limit of spatial sampling, increasing the number of horizontal loudspeakers influence little on BLLS then timbre. Above the limit, however, the BLLS for Ambisoncis reproduction deviate from those of target sound field. The extent of deviation depends on both the direction of target sound field and the number of loudspeakers. Increasing the number of horizontal loudspeakers may increase the change of BLLS then timbre in some cases, but reduce the change in some other cases. For MOA, the influence of the number of horizontal loudspeakers on BLLS and timbre reduces when virtual source departs from horizontal plane to the high or low elevation. The subjective evaluation experiment also validates the analysis.
{"title":"Influence of the Number of Loudspeakers on the Timbre in Horizontal and Mixed-Order Ambisoncis Reproduction","authors":"Haiming Mai, Bo-sun Xie, Jianliang Jiang, D. Rao, Yang Liu","doi":"10.32604/SV.2019.04275","DOIUrl":"https://doi.org/10.32604/SV.2019.04275","url":null,"abstract":"Ambisonics is a series of flexible spatial sound reproduction systems based on spatial harmonics decomposition of sound field. Traditional horizontal and spatial Ambisonics reconstruct horizontal and spatial sound field with certain order of spatial harmonics, respectively. Both the Shannon-Nyquist spatial sampling frequency limit for accurately reconstructing sound field and the complexity of system increase with the increasing order of Ambisonics. Based on the fact that the horizontal localization resolution of human hearing is higher than vertical resolution, mixed-order Ambisonics (MOA) reconstructs horizontal sound field with higher order spatial harmonics, while reconstructs vertical sound field with lower order spatial harmonics, and thereby reaches a compromise between the perceptual performance and the complexity of system. For a given order horizontal Ambisoncis or MOA reproduction, the number of horizontal loudspeakers is flexible, providing that it exceeds some low limit. By using Moore’s revised loudness model, the present work analyzes the influence of the number of horizontal loudspeakers on timbre both in horizontal Ambisonics and MOA reproduction. The binaural loudness level spectra (BLLS) of Ambisoncis reproduction are calculated and then compared with those of target sound field. The results indicate that below the Shannon-Nyquist limit of spatial sampling, increasing the number of horizontal loudspeakers influence little on BLLS then timbre. Above the limit, however, the BLLS for Ambisoncis reproduction deviate from those of target sound field. The extent of deviation depends on both the direction of target sound field and the number of loudspeakers. Increasing the number of horizontal loudspeakers may increase the change of BLLS then timbre in some cases, but reduce the change in some other cases. For MOA, the influence of the number of horizontal loudspeakers on BLLS and timbre reduces when virtual source departs from horizontal plane to the high or low elevation. The subjective evaluation experiment also validates the analysis.","PeriodicalId":49496,"journal":{"name":"Sound and Vibration","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79539285","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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