Pub Date : 2018-12-28DOI: 10.1177/1461348418819405
Yen Liang Yeh
This paper uses the Barycentric Lagrange interpolation method to explore the free vibration of a plate with the regular and irregular domain using the Chebyshev function, allowing us to consider multiple dimensions. From our results, it can be shown that the Barycentric Lagrange interpolation method can solve three-dimensional problems. In the analysis, we can see that the Barycentric Lagrange interpolation method can solve the dynamic motion of the plate with regular domain, and the error of the simulation can be reduced to 0.15%. The effect of the geometric node number on the simulated error of the natural frequency of the plate is very profound. The Barycentric Lagrange interpolation method and the extrapolation difference method can solve the natural frequency of the plate with irregular domain. The error of the simulation on the natural frequency can be reduced to 1.084%. This allows us to understand the vibration of the plate with the regular and irregular domain under various boundary conditions quickly.
{"title":"Vibration analysis of the plate with the regular and irregular domain by using the Barycentric Lagrange interpolation","authors":"Yen Liang Yeh","doi":"10.1177/1461348418819405","DOIUrl":"https://doi.org/10.1177/1461348418819405","url":null,"abstract":"This paper uses the Barycentric Lagrange interpolation method to explore the free vibration of a plate with the regular and irregular domain using the Chebyshev function, allowing us to consider multiple dimensions. From our results, it can be shown that the Barycentric Lagrange interpolation method can solve three-dimensional problems. In the analysis, we can see that the Barycentric Lagrange interpolation method can solve the dynamic motion of the plate with regular domain, and the error of the simulation can be reduced to 0.15%. The effect of the geometric node number on the simulated error of the natural frequency of the plate is very profound. The Barycentric Lagrange interpolation method and the extrapolation difference method can solve the natural frequency of the plate with irregular domain. The error of the simulation on the natural frequency can be reduced to 1.084%. This allows us to understand the vibration of the plate with the regular and irregular domain under various boundary conditions quickly.","PeriodicalId":56118,"journal":{"name":"Journal of Low Frequency Noise Vibration and Active Control","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2018-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/1461348418819405","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"65361714","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}
Pub Date : 2018-12-03DOI: 10.1177/1461348418813031
Mohammad Abdulrahman Al-Mashhadani
The analysis of the random vibrations that occur during the flight of the unmanned aerial vehicles is important, as these random vibrations have random characteristic properties and have the ability to decrease the endurance of such systems. The accuracy of data collected from sensors in the unmanned aerial vehicle system is important for the flight control system. The transferring of these data among different sensors such as inertial measurement unit, axis accelerometers, GPS or cameras is usually affected by many factors. One of the important factors is the random vibration, which is usually caused by aerodynamic excitation or air turbulence. The problem of random vibrations has been studied for a long time and explained in many text books. In this study, the author introduces a mathematical analysis for random vibrations that are independent of their sources by considering these vibrations as a random and non-stationary process and designs a control methodology based on expectations and probability theory to reduce the effect of these vibrations. The analysis used in this research is based on the assumptions of practical approximation techniques.
{"title":"Random vibrations in unmanned aerial vehicles, mathematical analysis and control methodology based on expectation and probability","authors":"Mohammad Abdulrahman Al-Mashhadani","doi":"10.1177/1461348418813031","DOIUrl":"https://doi.org/10.1177/1461348418813031","url":null,"abstract":"The analysis of the random vibrations that occur during the flight of the unmanned aerial vehicles is important, as these random vibrations have random characteristic properties and have the ability to decrease the endurance of such systems. The accuracy of data collected from sensors in the unmanned aerial vehicle system is important for the flight control system. The transferring of these data among different sensors such as inertial measurement unit, axis accelerometers, GPS or cameras is usually affected by many factors. One of the important factors is the random vibration, which is usually caused by aerodynamic excitation or air turbulence. The problem of random vibrations has been studied for a long time and explained in many text books. In this study, the author introduces a mathematical analysis for random vibrations that are independent of their sources by considering these vibrations as a random and non-stationary process and designs a control methodology based on expectations and probability theory to reduce the effect of these vibrations. The analysis used in this research is based on the assumptions of practical approximation techniques.","PeriodicalId":56118,"journal":{"name":"Journal of Low Frequency Noise Vibration and Active Control","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2018-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/1461348418813031","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"65361648","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}
Pub Date : 2009-06-01DOI: 10.1260/0263-0923.28.2.105
Frits van den Berg
Suffering from more or less continuous and more or less steady low pitched sounds at home can be a serious threat to well-being. Often the sound source is not obvious or cannot be found. In many cases there is no clear evidence from the analysis of the ambient sound what the disturbing sound could be. Thus Low Frequency Noise (LFN) has become an ominous concept, a confrontation between sufferers asking for understanding and a solution and experts who are frequently helpless. From reported measurements one must conclude that at least in some cases it is improbable or even impossible that LFN is actually present at a relevant level. Although, even then, sufferers often are convinced there has to be a real, external source. A much simpler explanation may be there is not, but the sound originates within the person. When brought in a very quiet environment, normally hearing people often hear low pitched and other sounds not physically present: phantom sounds. A hypothesis is that, when the presence of a physical sound cannot be confirmed, LFN sufferers hear low pitched phantom sounds as other people would in a dead quiet place, but do not recognize it than such. It may help sufferers to know this is a neurological phenomenon, not a psychological one. More knowledge of the sufferer about such sounds combined with the presence of more real sound at home could help to relieve the complaints.
{"title":"Low Frequency Noise and Phantom Sounds","authors":"Frits van den Berg","doi":"10.1260/0263-0923.28.2.105","DOIUrl":"https://doi.org/10.1260/0263-0923.28.2.105","url":null,"abstract":"Suffering from more or less continuous and more or less steady low pitched sounds at home can be a serious threat to well-being. Often the sound source is not obvious or cannot be found. In many cases there is no clear evidence from the analysis of the ambient sound what the disturbing sound could be. Thus Low Frequency Noise (LFN) has become an ominous concept, a confrontation between sufferers asking for understanding and a solution and experts who are frequently helpless. From reported measurements one must conclude that at least in some cases it is improbable or even impossible that LFN is actually present at a relevant level. Although, even then, sufferers often are convinced there has to be a real, external source. A much simpler explanation may be there is not, but the sound originates within the person. When brought in a very quiet environment, normally hearing people often hear low pitched and other sounds not physically present: phantom sounds. A hypothesis is that, when the presence of a physical sound cannot be confirmed, LFN sufferers hear low pitched phantom sounds as other people would in a dead quiet place, but do not recognize it than such. It may help sufferers to know this is a neurological phenomenon, not a psychological one. More knowledge of the sufferer about such sounds combined with the presence of more real sound at home could help to relieve the complaints.","PeriodicalId":56118,"journal":{"name":"Journal of Low Frequency Noise Vibration and Active Control","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2009-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1260/0263-0923.28.2.105","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66039434","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}
Pub Date : 2008-12-01DOI: 10.1260/026309208786926787
J. Ljungberg
The aim of this review is to shed light on a research area that concerns the studies of psychological responses to combined exposures of noise and whole-body vibration (WBV). Vehicle drivers are a group of workers that are often exposed to multiple stressors like noise, WBV and mental loads. Degraded performance because of environmental stressors may lead to injury or accidents. Standards that govern health risk assessment do not take into consideration the complexities of these multiple exposure environments (ISO 1997a, ISO 1999). Some studies have shown that the effect of one factor may be different than the effect of two factors presented together. For example, negative combined effects have been found in tracking tasks (Sommer and Harris, 1973), in arithmetic tasks (Harris and Schoenberger, 1980), as well as in subjective ratings (Ljungberg, Neely, Lundstrom, 2004), although in many of the studies the noise and WBV stimuli have been very unlike those that can be found in real workmg environments. Applying methods from the “irrelevant sound” paradigm (e.g. Jones, 1990) by using short-term memory tasks with a serial component as well as focus on frequencies rather than level has been revealed to tap the resources both objectively and subjectively more in both noise and WBV studies (e.g. Banbury et al. 2001; Kjellberg, 1990) Still, most experiments that have been conducted have focused on rather short exposure times in controlled laboratory settings. Using longer exposure times might also reveal other results since longer exposure times may be negatively related to sensitivity to noise and WBV (Abbate et al. 2004; Neely, Lundstrom, and Bjorkvist, 2002, Weinstein, 1978)
这篇综述的目的是为噪声和全身振动(WBV)联合暴露的心理反应研究提供一个新的研究领域。汽车司机是一群经常暴露于多种压力源的工人，如噪音、WBV和精神负荷。由于环境压力导致的性能下降可能导致伤害或事故。管理健康风险评估的标准没有考虑到这些多重接触环境的复杂性(ISO 1997a, ISO 1999)。一些研究表明，一个因素的影响可能不同于两个因素共同作用的影响。例如，在跟踪任务(Sommer and Harris, 1973)、算术任务(Harris and Schoenberger, 1980)以及主观评分(Ljungberg, Neely, Lundstrom, 2004)中发现了负面的综合效应，尽管在许多研究中，噪音和WBV刺激与在真实工作环境中发现的刺激非常不同。应用“无关声音”范式的方法(例如Jones, 1990)，通过使用具有串行分量的短期记忆任务以及关注频率而不是水平，在噪声和WBV研究中都揭示了更多地利用客观上和主观上的资源(例如Banbury等人，2001;Kjellberg, 1990)尽管如此，大多数已经进行的实验都集中在受控的实验室环境中相当短的暴露时间。使用较长的曝光时间也可能揭示其他结果，因为较长的曝光时间可能与对噪声和WBV的敏感性负相关(Abbate等人，2004;Neely, Lundstrom, and Bjorkvist, 2002; Weinstein, 1978)
{"title":"Combined Exposures of Noise and Whole-Body Vibration and the effects on Psychological Responses, a Review","authors":"J. Ljungberg","doi":"10.1260/026309208786926787","DOIUrl":"https://doi.org/10.1260/026309208786926787","url":null,"abstract":"The aim of this review is to shed light on a research area that concerns the studies of psychological responses to combined exposures of noise and whole-body vibration (WBV). Vehicle drivers are a group of workers that are often exposed to multiple stressors like noise, WBV and mental loads. Degraded performance because of environmental stressors may lead to injury or accidents. Standards that govern health risk assessment do not take into consideration the complexities of these multiple exposure environments (ISO 1997a, ISO 1999). Some studies have shown that the effect of one factor may be different than the effect of two factors presented together. For example, negative combined effects have been found in tracking tasks (Sommer and Harris, 1973), in arithmetic tasks (Harris and Schoenberger, 1980), as well as in subjective ratings (Ljungberg, Neely, Lundstrom, 2004), although in many of the studies the noise and WBV stimuli have been very unlike those that can be found in real workmg environments. Applying methods from the “irrelevant sound” paradigm (e.g. Jones, 1990) by using short-term memory tasks with a serial component as well as focus on frequencies rather than level has been revealed to tap the resources both objectively and subjectively more in both noise and WBV studies (e.g. Banbury et al. 2001; Kjellberg, 1990) Still, most experiments that have been conducted have focused on rather short exposure times in controlled laboratory settings. Using longer exposure times might also reveal other results since longer exposure times may be negatively related to sensitivity to noise and WBV (Abbate et al. 2004; Neely, Lundstrom, and Bjorkvist, 2002, Weinstein, 1978)","PeriodicalId":56118,"journal":{"name":"Journal of Low Frequency Noise Vibration and Active Control","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2008-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1260/026309208786926787","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66039340","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}
Pub Date : 1995-06-01DOI: 10.1177/026309239501400205
Henrik MØller
The article, published in the most recent issue of the Journal, presents measurements of low and infrasonic noise emitted from an industrial zone and transmitted into a residential area. The measurements seem to have been carried out with relevant equipment and care, and the results are very much in line with, what I believe can be found in many residential areas lying close to industrial zones. However, the authors have used G-weighted levels for evaluation of noise with significant energy in the range about 20 Hz, despite the fact that the Gcurve has a low frequency cut-off at 20 Hz. This misunderstanding leads to peculiar conclusions, and it calls for comments. The article may leave the reader with the impression that infrasound having G-weighted levels as low as 62-70 dB can be perceived by humans and give rise to complaints. This indication is far from the presently accepted threshold of perception of 90-100 dB(G), and it certainly cannot be concluded on basis of the observations reported. The authors also use unweighted levels, but filtered with a low pass filter at 20 Hz, and obviously this does not change the problem. The introduction of the article reports on "reasons for complaints ... of acoustical origin", and on problems relating to infrasound as being "of increasing importance". Measurements within the residential area show Gweighted levels of 62-70 dB, and levels of 57-66 dB, when measured linearly up to 20 Hz (lower limit not reported). The authors do not mention audibility explicitly, but state that these levels are "harmless to the human hearing organs". Taken the introduction into account, the reader may understand that the measured levels can be perceived by humans, but they do not damage the ear. The authors continue by claiming that the "... possibility of non-auditory effects of infrasound on the housing estate inhabitants cannot be definitely precluded ...". Well it cannot be precluded, but on the other hand, nothing in the study has suggested that infrasound should be the cause of the effects, and the statement would have been equally true, had the G-weighted levels been even lower. No effort was done to report more precisely on the non-auditory effects and to discuss their existence, nature and origin. Nevertheless, the connection to infrasound is suggested to the reader without the slightest foundation in the study. The authors seem unnecessarily concentrated on the infrasonic region. Their
{"title":"Comments to: Infrasounds in Residential Area – Case Study1","authors":"Henrik MØller","doi":"10.1177/026309239501400205","DOIUrl":"https://doi.org/10.1177/026309239501400205","url":null,"abstract":"The article, published in the most recent issue of the Journal, presents measurements of low and infrasonic noise emitted from an industrial zone and transmitted into a residential area. The measurements seem to have been carried out with relevant equipment and care, and the results are very much in line with, what I believe can be found in many residential areas lying close to industrial zones. However, the authors have used G-weighted levels for evaluation of noise with significant energy in the range about 20 Hz, despite the fact that the Gcurve has a low frequency cut-off at 20 Hz. This misunderstanding leads to peculiar conclusions, and it calls for comments. The article may leave the reader with the impression that infrasound having G-weighted levels as low as 62-70 dB can be perceived by humans and give rise to complaints. This indication is far from the presently accepted threshold of perception of 90-100 dB(G), and it certainly cannot be concluded on basis of the observations reported. The authors also use unweighted levels, but filtered with a low pass filter at 20 Hz, and obviously this does not change the problem. The introduction of the article reports on \"reasons for complaints ... of acoustical origin\", and on problems relating to infrasound as being \"of increasing importance\". Measurements within the residential area show Gweighted levels of 62-70 dB, and levels of 57-66 dB, when measured linearly up to 20 Hz (lower limit not reported). The authors do not mention audibility explicitly, but state that these levels are \"harmless to the human hearing organs\". Taken the introduction into account, the reader may understand that the measured levels can be perceived by humans, but they do not damage the ear. The authors continue by claiming that the \"... possibility of non-auditory effects of infrasound on the housing estate inhabitants cannot be definitely precluded ...\". Well it cannot be precluded, but on the other hand, nothing in the study has suggested that infrasound should be the cause of the effects, and the statement would have been equally true, had the G-weighted levels been even lower. No effort was done to report more precisely on the non-auditory effects and to discuss their existence, nature and origin. Nevertheless, the connection to infrasound is suggested to the reader without the slightest foundation in the study. The authors seem unnecessarily concentrated on the infrasonic region. Their","PeriodicalId":56118,"journal":{"name":"Journal of Low Frequency Noise Vibration and Active Control","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"1995-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/026309239501400205","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"65060613","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}
Pub Date : 1994-06-01DOI: 10.1177/026309239401300203
Hans-Juergen von Martens, A. Taubner
INTRODUCTION In the past ten years. novel air-borne vibration exciters and interferometric measuring facilities have been developed allowing the accurate dynamic calibration of accelerometers. velocimeters and displacement transducers to be performedl-l. Since 1990, standard methods for the excitation and measurement of angular accelerations, angular velocities and rotational angles with specific time dependences have been developed at the Physikalisch-Technische Bundesanstalt (PTB). The facilities available in the PTB's "Acceleration" laboratory in Berlin for the calibration of translational and rotational quantity transducers are based on a universal concept for both the generation and measurement of the motion quantities. This concept and its application, especially for the low-frequency calibration of transducers. are presented in this paper.
{"title":"Interferometric Low-Frequency Calibration of Translation and Rotation Quantity Transducers","authors":"Hans-Juergen von Martens, A. Taubner","doi":"10.1177/026309239401300203","DOIUrl":"https://doi.org/10.1177/026309239401300203","url":null,"abstract":"INTRODUCTION In the past ten years. novel air-borne vibration exciters and interferometric measuring facilities have been developed allowing the accurate dynamic calibration of accelerometers. velocimeters and displacement transducers to be performedl-l. Since 1990, standard methods for the excitation and measurement of angular accelerations, angular velocities and rotational angles with specific time dependences have been developed at the Physikalisch-Technische Bundesanstalt (PTB). The facilities available in the PTB's \"Acceleration\" laboratory in Berlin for the calibration of translational and rotational quantity transducers are based on a universal concept for both the generation and measurement of the motion quantities. This concept and its application, especially for the low-frequency calibration of transducers. are presented in this paper.","PeriodicalId":56118,"journal":{"name":"Journal of Low Frequency Noise Vibration and Active Control","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"1994-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/026309239401300203","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"65060595","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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