Acta Acustica united with Acustica最新文献_第4页

Role of Plate Length on Noise from Wall Jets 板长对壁面射流噪声的影响

Acta Acustica united with Acustica Pub Date : 2019-11-01 DOI: 10.3813/aaa.919374

Rahul S. Arackal, T. Jothi

{"title":"Role of Plate Length on Noise from Wall Jets","authors":"Rahul S. Arackal, T. Jothi","doi":"10.3813/aaa.919374","DOIUrl":"https://doi.org/10.3813/aaa.919374","url":null,"abstract":"The present study experimentally investigates the effect of the growth of inner layer on noise emission characteristics of wall jets. The plate length L considered for the current study vary in the range of L/h = 2.5 to 30, where h is the nozzle height. The jet\u0000 is issued from a nozzle having the exit dimensions of 20 cm in width and 2 cm in height h. The jet Reynolds number, based on the nozzle height and jet exit velocity Uj, is varied up to 7.0 · 104. Acoustic measurements revealed the distinct variations in\u0000 the noise levels with different plate lengths. The L/h = 2.5 wall jet has an increase in noise levels by around 10 dB compared to that of a free jet (background noise). Wall jets in the range of L/h = 5 to 20 radiate higher noise levels compared to other plates, while the least\u0000 noise emissions are observed from fully developed wall jets (L/h > 20). The significant sources identified for noise emissions are the trailing edge and the secondary shear layer in the wall jets. The low frequency noise corresponding to the Strouhal number (based on h) below\u0000 0.2 is characterized as the trailing edge noise. The spectra of the wall jets collapse in the Strouhal number range (based on the inner layer thickness of wall jets) of ∼0.2 to 1.0 indicating the secondary shear layer noise of wall jets.","PeriodicalId":35085,"journal":{"name":"Acta Acustica united with Acustica","volume":"47 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80490248","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}

引用次数: 3

A Review of Gunshot Noise as Factor in Hearing Disorders 枪声噪声作为听力障碍因素的研究进展

Acta Acustica united with Acustica Pub Date : 2019-11-01 DOI: 10.3813/aaa.919371

Ewa B. Skrodzka, A. Wicher, Roman Gołe¸biewski

{"title":"A Review of Gunshot Noise as Factor in Hearing Disorders","authors":"Ewa B. Skrodzka, A. Wicher, Roman Gołe¸biewski","doi":"10.3813/aaa.919371","DOIUrl":"https://doi.org/10.3813/aaa.919371","url":null,"abstract":"The impulse noise produced by personal weapons (guns, rifles, shotguns) during military activity, and while people engage in sport, training and hunting, is a threat to the auditory systems of soldiers, civilians, policemen, hunters, forest officers, sportspeople and bystanders not\u0000 actively engaged in professional or recreational firing. An overview of noise levels generated by different types of weapon is provided, and potential short-term and long-term consequences for the human auditory system are described. The mean values of LC, peak sound pressure level during\u0000 the shot, at the shooter's ears, for various types of weapons are approximately 160 dB SPL. These are levels that can cause permanent, irreversible negative effects on hearing (hearing loss, tinnitus, etc.) even as a result of a single shot being fired. One of the largest groups of weapon\u0000 users in Poland (about 120 thousand) are hunters and field masters. They are not obligated by any regulations to protect their auditory systems from impulse noise. This means that this group of firearm users is at particularly high risk of hearing damage. On the basis of the literature review,\u0000 it is shown that hearing exposure to high-level impulse noise such as a gunshot can result in such consequences as damage to the middle ear and destruction of the outer/inner hair cells in the cochlea. Especially difficult to diagnose is 'hidden hearing loss', i.e. damage to the synaptic connections\u0000 between the hair cells of the inner ear and the auditory nerve fibres, which is not reflected in the results of basic audiometric testing and can cause hearing problems many years after impulse noise exposure. The wide range of negative consequences of gunfire noise clearly indicates the need\u0000 for the hearing of the shooters to be protected.","PeriodicalId":35085,"journal":{"name":"Acta Acustica united with Acustica","volume":"25 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85668399","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}

引用次数: 4

Measurement of Sound Absorption Using a Single Fixed Microphone in a Circular Pulse-Tube 在圆形脉冲管内使用单个固定麦克风测量吸声

Acta Acustica united with Acustica Pub Date : 2019-11-01 DOI: 10.3813/aaa.919399

Zheng-yu Wei, H. Hou, Nansha Gao, Yunke Huang, Jianhua Yang

引用次数: 1

Study on Natural Frequencies of Transverse Free Vibration of Functionally Graded Axis Beams by the Differential Quadrature Method 用微分正交法研究功能梯度轴梁横向自由振动固有频率

Acta Acustica united with Acustica Pub Date : 2019-11-01 DOI: 10.3813/aaa.919388

Jinlong Zhang, Liaojun Zhang, R. Ge, Li Yang, J. Xia

引用次数: 0

Detection and Evaluation of Amplitude Modulation From a Wind Energy Development, Ireland 爱尔兰风能开发的调幅检测与评估

Acta Acustica united with Acustica Pub Date : 2019-11-01 DOI: 10.3813/aaa.919383

S. Jennings, J. Kennedy

{"title":"Detection and Evaluation of Amplitude Modulation From a Wind Energy Development, Ireland","authors":"S. Jennings, J. Kennedy","doi":"10.3813/aaa.919383","DOIUrl":"https://doi.org/10.3813/aaa.919383","url":null,"abstract":"Amplitude modulation (AM) is a characteristic of wind turbine noise that has only been recognised as an issue in recent years. It is a characteristic related to aerodynamic noise and descriptions of it include \"swishing\", \"whooshing\" or less frequently a \"thumping\" sound. Due to increased\u0000 awareness among exposed communities AM presents a potentially serious obstacle to future wind farm developments. This work reports on the application of a recently developed calculation method for AM in a practical setting. Correlations will be drawn with subjective reports of AM by nearby\u0000 residents keeping a noise diary. The suitability of the method and its ability to quantitatively confirm subjective reports of AM will be assessed. A study is presented here whereby subjectively recorded occurrences of AM by residents living near a wind energy development in Ireland are correlated\u0000 to calculated levels over a twenty day period. In order to detect and calculate AM a method published by the Amplitude Modulation Working Group of the Institute of Acoustics, referred to as the Reference Method, is applied. A subjective assessment of the sound recordings to confirm the presence\u0000 of AM is discussed, including estimating the expected frequency range that AM occurs. The results of the Reference Method calculation are presented for periods with and without a subjective report of AM by the residents. Consideration is given to the criteria and thresholds for valid AM ratings\u0000 within the Reference Method especially where intermittent periods of AM are identified. The Reference Method is shown to be highly suitable as a quantitative measure of AM which correlates well with subjective reports. Caution must be taken when using the method as valid periods of AM may\u0000 be overlooked due to the rigorous detection thresholds set by the method.","PeriodicalId":35085,"journal":{"name":"Acta Acustica united with Acustica","volume":"56 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80200691","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}

引用次数: 3

Numerical Modelling of Boundary Layers and Far Field Acoustic Propagation in Thermoviscous Fluid 热粘性流体边界层及远场声波传播数值模拟

Acta Acustica united with Acustica Pub Date : 2019-11-01 DOI: 10.3813/aaa.919392

N. Joly, P. Honzík

引用次数: 1

Lumped Parameter Description of Thermoviscous Acoustics in Tubes with Equilateral Triangular Cross-Sections 等边三角形截面管内热粘性声学的集总参数描述

Acta Acustica united with Acustica Pub Date : 2019-11-01 DOI: 10.3813/aaa.919407

R. Christensen

引用次数: 0

Low-Frequency Guided Wave Quantitative Reconstruction of Corrosion in Plates, 1D Diffraction Problem 板材腐蚀的低频导波定量重建，一维衍射问题

Acta Acustica united with Acustica Pub Date : 2019-11-01 DOI: 10.3813/aaa.919378

William Cailly, H. Walaszek, Sébastien Brzuchacz, Fan Zhang, P. Lasaygues

{"title":"Low-Frequency Guided Wave Quantitative Reconstruction of Corrosion in Plates, 1D Diffraction Problem","authors":"William Cailly, H. Walaszek, Sébastien Brzuchacz, Fan Zhang, P. Lasaygues","doi":"10.3813/aaa.919378","DOIUrl":"https://doi.org/10.3813/aaa.919378","url":null,"abstract":"Guided Wave Tomography is a nondestructive imaging technique that consists in inverting guided wave propagation data to localize defects. In particular, this technique should provide quantitative information about the corrosion state of metallic plates by reconstructing a thickness\u0000 map from diffraction or time-of-flight measurements. In this paper we first present an analytical framework for corrosion profile reconstruction considering the 1D case. Due to the fact that, in practice, the low frequency ultrasound range (typically 50 to 100 kHz) is used for long range inspections,\u0000 the first-order shear deformation approximation is relevant for plate thicknesses encountered in metallic structures. This leads to an analytical description of guided wave phenomena: diffraction, refraction and mode conversion, for 5 modes: A0, S0, SH0, A1 and SH1. The validity of an analytical\u0000 approach to modeling thickness loss defects, in particular the validity of the first Born approximation, is discussed by comparing with elastodynamic numerical results. The comparison results show that the nonlinear behavior with depth increase, or width increase, of the defects (distortion)\u0000 can be fully described using a multimodal high order Born series. Consequently, a consistent iterative inversion Born series based algorithm can be used to deal with the reconstruction of strong thickness losses.","PeriodicalId":35085,"journal":{"name":"Acta Acustica united with Acustica","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90422286","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}

引用次数: 1

High-Frequency Diffraction of a Point Source Field by a Strongly Elongated Elliptic Cylinder 强细长椭圆圆柱对点源场的高频衍射

Acta Acustica united with Acustica Pub Date : 2019-11-01 DOI: 10.3813/aaa.919372

I. Andronov

引用次数: 0

Excitation of Non-Wave Modes by Sound of Arbitrary Frequency in a Chemically Reacting Gas 化学反应气体中任意频率声音对非波模式的激发

Acta Acustica united with Acustica Pub Date : 2019-11-01 DOI: 10.3813/aaa.919373

A. Perelomova

引用次数: 2