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Fanigliulo, Roberto, Lindoro Del Duca, Laura Fornaciari, Renato Grilli, Roberto Tomasome, and Danieele Pochi. "Efficiency of an ANC system in the tractor cabin under controlled engine workload." Noise Control Engineering Journal 68, no. 5 (September 1, 2020): 339–57. http://dx.doi.org/10.3397/1/376829.
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The noise at the driver seat of an agricultural tractor is produced mostly by the engine. Its characteristic broadband noise spectrum varies considerably with engine workload. The passive noise control techniques adopted in tractor cabins, based on the application of sound-absorbing and sound-proofing materials, are effective against medium-high frequencies noise components. The residual noise in sound-proof cabins is characterized by tonal emissions with low frequency components (< 500 Hz) but regarded as responsible for various disorders and diseases following long-term exposure. In addition to the "A" weighting filter adopted to evaluate occupational exposure to noise, other approaches are reported in the scientific literature considered more appropriate to evaluate low frequency noise (LFN), as well as studies testifying the effectiveness of active noise control (ANC) technologies in the low frequency range. In this article, the performance of an ANC system is evaluated in its ability to reduce noise levels inside the soundproof cabin of an agricultural tractor. To test this system, spectro-phonometric measurements of the equivalent linear sound pressure level were conducted under controlled and repeatable engine workloads, obtained by connecting the tractor to a dynamometric brake, while simultaneously acquiring the related engine performance curves. Altogether, three different couples of loudspeakers were tested. Frequency analysis in one-third octave band showed that the ANC system was mainly effective against LFN components (below 120 Hz) with peaks of reduction up to 20 dB. Then, on the basis of indications from previous studies, the data of linear sound pressure levels were processed applying the "A", "B", and "C" weighting filters, to show the different emphasis given to the effects of the system. Eventually, a point-by-point composition of the equivalent levels of sound pressure was drawn over the whole range of the engine, to highlight the conditions in which the ANC system was more effective.
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WATANABE, KEN'ICHI. "Ear noises. II. Ear acoustic emission and ear noise control by a band noise trout car." AUDIOLOGY JAPAN 38, no. 5 (1995): 595–96. http://dx.doi.org/10.4295/audiology.38.595.
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Gabbert, Ulrich, Fabian Duvigneau, and Stefan Ringwelski. "NOISE CONTROL OF VEHICLE DRIVE SYSTEMS." Facta Universitatis, Series: Mechanical Engineering 15, no. 2 (August 2, 2017): 183. http://dx.doi.org/10.22190/fume170615009g.
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The paper presents an overall simulation approach to control the noise emission of car engines at a very early stage of the design process where no real prototypes are available. The suggested approach combines different physical models and couples different software tools such as multi-body analysis, fluid dynamics, structural mechanics, magneto-electrodynamics, thermodynamics, acoustics and control as well. The general overall simulation methodology is presented first. Then, this methodology is applied to a combustion engine in order to improve its acoustical behavior by passive means, such as changing the stiffness and the use of damping materials to build acoustic and thermal encapsulations. The active control by applying piezoelectric patch actuators at the oil sump as the noisiest part of the engine is discussed as well. The sound emission is evaluated by hearing tests and a mathematical prediction model of the human perception. Finally, it is shown that the presented approach can be extended to electric engines, which is demonstrated at a newly developed electric wheel hub motor.
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Akin Ocal, F. C., G. G. Kesici, S. G. Gurgen, R. Ocal, and S. Erbek. "The effect of intratympanic oxytocin treatment on rats exposed to acoustic trauma." Journal of Laryngology & Otology 133, no. 06 (May 17, 2019): 466–76. http://dx.doi.org/10.1017/s0022215119001014.
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AbstractObjectiveTo investigate whether oxytocin can prevent ototoxicity related to acoustic trauma.MethodsTwenty-eight rats were divided into four groups: noise (group 1), control (group 2), noise plus oxytocin (group 3), and oxytocin (group 4). Intratympanic oxytocin was administered on days 1, 2, 4, 6, 8 and 10 in groups 3 and 4. Groups 1 and 3 were exposed to acoustic trauma. Distortion product otoacoustic emission and auditory brainstem response testing were performed in all groups.ResultsIn group 1, auditory brainstem response thresholds increased significantly after acoustic trauma. In group 3, auditory brainstem response thresholds increased significantly on day 1 after acoustic trauma, but there were no significant differences between thresholds at baseline and on the 7th and 21st days. In group 1, significant differences were observed between distortion product otoacoustic emission signal-to-noise ratios measured before and on days 1, 7 and 21 after acoustic trauma. In group 3, no significant differences were observed between the distortion product otoacoustic emission signal-to-noise ratios measured before and on days 7 and 21 after acoustic trauma.ConclusionOxytocin had a therapeutic effect on rats exposed to acoustic trauma in this experiment.
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Barat, Vera, Artem Marchenkov, Dmitry Kritskiy, Vladimir Bardakov, Marina Karpova, Mikhail Kuznetsov, Anastasia Zaprudnova, Sergey Ushanov, and Sergey Elizarov. "Structural Health Monitoring of Walking Dragline Excavator Using Acoustic Emission." Applied Sciences 11, no. 8 (April 11, 2021): 3420. http://dx.doi.org/10.3390/app11083420.
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The article is devoted to the organization of the structural health monitoring of a walking dragline excavator using the acoustic emission (AE) method. Since the dragline excavator under study is a large and noisy industrial facility, preliminary prospecting researches were carried out to conduct effective control by the AE method, including the study of AE sources, AE waveguide, and noise parameters analysis. In addition, AE filtering methods were improved. It is shown that application of the developed filtering algorithms allows to detect AE impulses from cracks and defects against a background noise exceeding the useful signal in amplitude and intensity. Using the proposed solutions in the monitoring of a real dragline excavator during its operation made it possible to identify a crack in one of its elements (weld joint in a dragline back leg).
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Kowalski, K. J., A. J. Brzeziński, J. B. Król, P. Radziszewski, and Ł. Szymański. "Traffic Analysis and Pavement Technology as a Tool for Urban Noise Control." Archives of Civil Engineering 61, no. 4 (December 1, 2015): 107–26. http://dx.doi.org/10.1515/ace-2015-0039.
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Traffic related noise is currently considered as an environmental pollution. Paper presents results of multidirectional study attempting to serve urban traffic without the need to erect noise barriers interfering urban space. Initial concept of the road expansion included construction of 1000 m of noise barriers dividing city space. Improvement in the acoustic conditions after construction completion is possible due to the applied noise protection measures: vehicle speed limit, smooth of traffic flow, use of road pavement of reduced noise emission and the technical improvement of the tramway.
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Chraponska, Anna, Stanislaw Wrona, Jaroslaw Rzepecki, Krzysztof Mazur, and Marek Pawelczyk. "Active Structural Acoustic Control of an Active Casing Placed in a Corner." Applied Sciences 9, no. 6 (March 13, 2019): 1059. http://dx.doi.org/10.3390/app9061059.
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Electric appliances used in workplaces and everyday life often generate a low-frequency noise, which affects human body systems. Passive methods employed to reduce noise are not effective at low frequencies. The classical approach to active noise control practically involves the generation of local zones of quiet, whereas at other areas the noise is reinforced. Moreover, it usually requires a large number of secondary sound sources. Hence, an active casing approach has been developed. The active casing panels’ vibrations are controlled to reduce the device noise emission. Efficiency of this method has been previously confirmed by the authors and the results have been reported in multiple journal publications. However, in the previous research experiments, the active casing was placed at a distance from the enclosure walls. In this research, the active casing is located in a corner and such placement is intentionally used to facilitate the active control system’s operation. The noise reduction performance is investigated at multiple configurations, including a range of distances from the corner and different error microphone arrangements. The analysis of both primary and secondary paths is given. Advantages and drawbacks of different active casing configurations are presented and discussed.
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Seleznev, M. N., and A. Yu Vinogradov. "The application of acoustic emission method for ultrasonic fatigue testing monitoring." Vektor nauki Tol'yattinskogo gosudarstvennogo universiteta, no. 2 (2021): 47–56. http://dx.doi.org/10.18323/2073-5073-2021-2-47-56.
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The ultrasonic fatigue testing (USFT) is an effective method for rapid determination of the fatigue properties of structural materials under high cycle (≥106 cycles) loading. However, the occurrence and accumulation of fatigue damage with this test method remain uncertain due to the limitations of the existing measurement methods. Currently used monitoring methods allow detecting the fatigue cracks, but only in the late stages of failure. Despite the superior sensitivity to localized processes in materials, the use of the acoustic emission (AE) method in ultrasonic testing is extremely difficult due to the presence of resonant noise. This work aimed to suppress resonant noise and extract the signal for early detection of fatigue damage. The authors tested the samples of the AlSi9Cu3 aluminum alloy under the asymmetric cyclic loading (R=0.1) at a resonant frequency of 19.5 kHz with a non-threshold AE registration. The fracture surfaces were analyzed by electron and optical microscopy. The authors processed AE by two different methods: (1) the digital filtering method consisted of detecting resonant noise and removing it from the spectrum; (2) the φ-function method consisted of differentiating the spectrogram by time. The processed spectrograms were integrated by the frequency with further extraction of the AE events using the threshold method. The digital filtering method revealed a correlation between AE signals and fatigue damage, whereas the undamaged control sample showed no signals. The φ-function technique demonstrated ambiguous results, showing high AE activity on the control sample.
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Wang, Zhong, Chang Zheng Chen, and Xiang Jun Kong. "Isolation System Design and Noise Control of Roots Blower Room." Advanced Materials Research 971-973 (June 2014): 1021–24. http://dx.doi.org/10.4028/www.scientific.net/amr.971-973.1021.
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With the actual case of isolation system design and noise control of roots blower room of a pharmaceutical factory in Shenyang taken into consideration, the overall computation was done on the basis of multi-vibration noise source. The vibration energy of equipments and noise propagation were analyzed both qualitatively and quantitatively with the spectral characteristics of vibration and wideband noise taken into account. Furthermore, the acoustic environment in the blower room was improved and the noise emission of the factory got down to the standard after the vibration isolation and noise reduction measures were applied. This work has important guiding significance and reference value for the projects on vibration isolation and noise control in the future.
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Khorsov, Petr, Nikolay Khorsov, and Vladimir Surzhikov. "Control of Defects on the Parameters of the Electromagnetic Response under Pulsed Mechanical Excitation of the Sample." Advanced Materials Research 1085 (February 2015): 316–18. http://dx.doi.org/10.4028/www.scientific.net/amr.1085.316.
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The paper assessed the possibility of using acoustic emission from the dielectric sample during stepwise loading. The electromagnetic signal from the sample was detected by using an apparatus of mechanical repeatedly pulsed excitation of the sample at each stage of loading. It was found that the response consists of a deterministic component (due to the excitation pulse) and random components noise and acoustic emission. It were allocated random components, calculated their standard deviations. The influence of the electromagnetic emission on standard deviation of the random component of response under step load on the specimen was evaluated. It has been shown that the component of the electromagnetic emission can be an informative parameter to evaluate defectiveness of the object of a dielectric material under load.
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Górski, Jarosław, Karol Szymanowski, Piotr Podziewski, Katarzyna Śmietańska, Paweł Czarniak, and Mariusz Cyrankowski. "Use of cutting force and vibro-acoustic signals in tool wear monitoring based on multiple regression technique for compreg milling." BioResources 14, no. 2 (March 7, 2019): 3379–88. http://dx.doi.org/10.15376/biores.14.2.3379-3388.
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This study focused on a computerised TCM (tool condition monitoring) system as a part of automated monitoring of the machining processes in the wood industry. The system’s principal task was to evaluate the actual state of tool wear without disrupting the normal course of machine tool exploitation for cutting force and vibro-acoustic signals analysis. During the experiment, five physical quantities that are generated during machining were measured and recorded: cutting forces in two directions (Fx, Fy), ultrasonic stress waves (acoustic emission – AE), acoustic pressure in the range of audible frequencies (noise – N), and acceleration of mechanical vibrations (V). Six pairs of tools were used in the experiment. One tool from each pair was experimental, the other was a control tool. Out of the five physical quantities generated during machining that were tested as an indirect source of information on the tool condition, signals of cutting forces and mechanical vibrations proved the most useful. Both acoustic emission and noise signals emerged as wholly inadequate as evidence to predict tool wear.
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Rastegaev, Igor, Dmitry Merson, Inna Rastegaeva, and Alexei Vinogradov. "A Time-Frequency Based Approach for Acoustic Emission Assessment of Sliding Wear." Lubricants 8, no. 5 (May 9, 2020): 52. http://dx.doi.org/10.3390/lubricants8050052.
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The acoustic emission method is one of few contemporary non-destructive testing techniques enabling continuous on-line health monitoring and control of tribological systems. However, the existence of multiple “pseudo”-acoustic emission (AE) and noise sources during friction, and their random occurrence poses serious challenges for researchers and practitioners when extracting “useful” information from the upcoming AE signal. These challenges and numerous uncertainties in signal classification prevent the unequivocal interpretation of results and hinder wider uptake of the AE technique despite its apparent advantages. Currently, the signal recording and processing technologies are booming, and new applications are born on this support. Specific tribology applications, therefore, call for developing new and tuning existing approaches to the online AE monitoring and analysis. In the present work, we critically analyze, compare and summarize the results of the application of several filtering techniques and AE signal classifiers in model tribological sliding friction systems allowing for the simulation of predominant wear mechanisms. Several effective schemes of AE data processing were identified through extensive comparative studies. Guidelines were provided for practical application, including the online monitoring and control of the systems with friction, characterizing the severity and timing of damage, on-line evaluation of wear as sliding contact tests and instrumented acceleration of tribological testing and cost reduction.
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Aksoy, F., R. Dogan, A. Yenigun, B. Veyseller, O. Ozturan, and B. Ozturk. "Thymoquinone treatment for inner-ear acoustic trauma in rats." Journal of Laryngology & Otology 129, no. 1 (January 2015): 38–45. http://dx.doi.org/10.1017/s0022215114002680.
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AbstractObjective:To investigate whether thymoquinone has any eliminative effects against inner-ear damage caused by acoustic trauma.Methods:Thirty-two male rats were divided into four groups. Group 1 was only exposed to acoustic trauma. Group 2 was given thymoquinone 24 hours before acoustic trauma and continued to receive it for 10 days after the trauma. Group 3 was only treated with thymoquinone, for 10 days. Group 4, the control group, suffered no trauma and received saline instead of thymoquinone. Groups 1 and 2 were exposed to acoustic trauma using 105 dB SPL white noise for 4 hours.Results:There was a significant decrease in distortion product otoacoustic emission values and an increase in auditory brainstem response thresholds in group 1 on days 1, 5 and 10, compared with baseline measurements. In group 2, a decrease in distortion product otoacoustic emission values and an increase in auditory brainstem response threshold were observed on day 1 after acoustic trauma, but measurements were comparable to baseline values on days 5 and 10. In group 3, thymoquinone had no detrimental effects on hearing. Similarly, the control group showed stable results.Conclusion:Thymoquinone was demonstrated to be a reparative rather than preventive treatment that could be used to relieve acoustic trauma.
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Shanbhag, Vignesh V., Thomas J. J. Meyer, Leo W. Caspers, and Rune Schlanbusch. "Defining acoustic emission-based condition monitoring indicators for monitoring piston rod seal and bearing wear in hydraulic cylinders." International Journal of Advanced Manufacturing Technology 115, no. 9-10 (May 28, 2021): 2729–46. http://dx.doi.org/10.1007/s00170-021-07340-8.
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AbstractFluid leakage from hydraulic cylinders is a major concern for the offshore industries as it directly affects hydraulic cylinder energy efficiency and causes environmental contamination. There have been attempts made in literature to develop robust condition monitoring techniques for hydraulic cylinders. However, most of these studies were performed to identify degradation of single components. Therefore, in this study, the aim is to monitor degradation of multiple components simultaneously in hydraulic cylinders using acoustic emissions. Experiments performed consist of three test phases and were performed using a hydraulic test rig. In the first test phase, the study is performed to identify acoustic emission features that can be used to monitor piston rod seal wear. In the second test phase, acoustic emission features are identified that can be used to understand bearing wear when unworn, semi-worn or worn piston rod seals are used in hydraulic test rig. In the third test phase, a run-to-failure test is conducted to identify acoustic emission features that can indicate fluid leakage initiation due to piston rod seal wear. The median frequency feature showed good repeatability in all the three test phases to identify piston rod seal wear, bearing wear and fluid leakage initiation during the initial stages in the hydraulic test rig. The proposed acoustic emission-based condition monitoring technique is robust and can be used for the hydraulic cylinders in the industries, as it identifies acoustic emission features based on particular frequency bands associated to specific components, making it less susceptible to noise from other components.
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Bianchi, S., A. Corsini, F. Rispoli, and A. G. Sheard. "Detection of aerodynamic noise sources in low-speed axial fans with tip end-plates." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 223, no. 6 (March 18, 2009): 1379–92. http://dx.doi.org/10.1243/09544062jmes1277.
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This article reports on the use of modified blade-tip configurations designed with a view to passive noise control in low-speed fans for compact cooling units. The addition of end-plates at the tip of a datum fan blade is shown to have a positive influence on the fan's rotor-only aero-acoustic signature. The aerodynamic effects of the modified blade tips are experimentally tested in a fully ducted configuration in the near field and far field using a correlation technique. The nature of the flow mechanisms in the blade-tip region are correlated with the specific end-plate design features and their role in the creation of overall acoustic emissions is clarified. The noise emitted by the fans is analysed in terms of coherent vortex structures, tip-leakage flow, and noise sources. Differences in human perception of the noise emitted to the environment are also investigated using a dot-pattern visualization. The study concludes that the modified tip configurations have a marked effect on tip-leakage vortex formation by altering the near-wall fluid paths on blade surfaces. The reduction in rotor noise emission is correlated with the control of tip-leakage flows produced by the tip end-plates.
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Faisal, Nadimul Haque, John A. Steel, Rehan Ahmed, R. L. Reuben, G. Heaton, and Bryan Allcock. "Application of Acoustic Emission for Monitoring the HVOF Thermal Spraying Process." Advanced Materials Research 13-14 (February 2006): 291–98. http://dx.doi.org/10.4028/www.scientific.net/amr.13-14.291.
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This research aims to characterise and quantify the acoustic emission (AE) generated during the high velocity oxy-fuel (HVOF) thermal spraying process, recorded using piezoelectric AE sensors. The HVOF process is very complex involving high temperature turbulent flow through a nozzle with entrained particles, the projection of these particles, and their interaction with the target surface. Process parameters such as gun speed, oxy-fuel pressure and powder specification affect various characteristics of the coating, including thermal residual stresses; the lamellar microstructure and the topology and geometry of pores, all formed when the fused powder hits the surface, forming “splats”. It is widely acknowledged in the thermal spray industry that existing quality control techniques and testing techniques need to be improved. New techniques which help to understand the effects of coating process parameters on the characteristics of the coating are therefore of value, and it was anticipated that recording the AE produced when the fused particles contact the surface would aid this understanding. As a first stage, we demonstrated here that AE associated with particle impact can, in fact, be discerned in the face of the considerable airborne and structure-borne noise. In order to do this, a new test method using a masking sheet with slits of varying size was developed. Thermal spraying was carried out for a range of spray gun speeds and process parameters. The AE was measured using a broad band AE sensor positioned on the back of the sample as the spot was traversed across it. The results show that the amplitude and energy of the AE signals is related to the spray gun speed, powder used and the oxy-fuel pressure. Using a simple geometrical model for particle impact, the measured AE was found to vary with the energy and number of particles impacting on the sample in a predictable way.
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Morzyński, Leszek, and Grzegorz Szczepański. "Active noise control system in a fire helmet – a proposal of the solution." Occupational Safety – Science and Practice 558, no. 3 (March 21, 2018): 11–15. http://dx.doi.org/10.5604/01.3001.0011.6431.
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An auditory warning signal emitted by a moving emergency vehicle is intended to inform other road users about an approaching emergency vehicle and the need to give way to it. Emission of a warning signal with the highest possible sound pressure level is the main method of ensuring the audibility and recognition of the warning signal by traffic participants at unknown and varying traffic noise, acoustic insulation of vehicles and noise in the interior of the vehicle. The A-weighted sound pressure level of the auditory warning signal reaching the interior of an emergency vehicle may exceed 90 dB, which can be harmful to the hearing, can adversely affect psychophysical fitness of the crew members and can significantly hinder verbal communication in the vehicle. This article presents the concept and results of numerical simulations of an active noise control system in fire helmets, which will reduce the exposure of the crew to the warning signal and improve the quality of verbal communication in an emergency vehicle. This system is integrated with the signal generation system. The Notch algorithm and the NLMS adaptation algorithm were used in the system's control algorithm. The construction of the controller was based on a microcontroller from the STM32F4 family.
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Sharma, Sidharath, Alberto Broatch, Jorge García-Tíscar, John M. Allport, and Ambrose K. Nickson. "Acoustic characteristics of a ported shroud turbocompressor operating at design conditions." International Journal of Engine Research 21, no. 8 (November 27, 2018): 1454–68. http://dx.doi.org/10.1177/1468087418814635.
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In this article, the acoustic characterisation of a turbocharger compressor with ported shroud design is carried out through the numerical simulation of the system operating under design conditions of maximum isentropic efficiency. While ported shroud compressors have been proposed as a way to control the flow near unstable conditions in order to obtain a more stable operation and enhance deep surge margin, it is often assumed that the behaviour under stable design conditions is characterised by a smooth, non-detached flow that matches an equivalent standard compressor. Furthermore, research is scarce regarding the acoustic effects of the ported shroud addition, especially under the design conditions. To analyse the flow field evolution and its relation with the noise generation, spectral signatures using statistical and scale-resolving turbulence modelling methods are obtained after successfully validating the performance and acoustic predictions of the numerical model with experimental measurements. Propagation of the frequency content through the ducts has been estimated with the aid of pressure decomposition methods to enhance the content coming from the compressor. Expected acoustic phenomena such as ‘buzz-saw’ tones, blade passing peaks and broadband noise are correctly identified in the modelled spectrum. Analysis of the flow behaviour in the ported shroud shows rotating structures through the slot that may impact the acoustic and vibration response. Further inspection of the pressure field through modal decomposition confirms the influence of the ported shroud cavity in noise generation and propagation, especially at lower frequencies, suggesting that further research should be carried out on the impact these flow enhancement solutions have on the noise emission of the turbocharger.
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BLEICHER, Friedrich, Christoph REICHL, Felix LINHARDT, Peter WIMBERGER, Christoph HABERSOHN, and Stephan KRALL. "INVESTIGATION OF NOISE TRANSMISSION OF A MACHINE TOOL ENCLOSURE." Journal of Machine Engineering 19, no. 3 (September 15, 2019): 5–17. http://dx.doi.org/10.5604/01.3001.0013.4076.
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Machine tools are highly integrated mechatronic systems consisting of dedicated mechanic design and integrated electrical equipment - in particular drive systems and the CNC-control - to realize the complex relative motion of tool towards work piece. Beside the process related capabilities, like static and dynamic stiffness as well as accuracy behavior and deviation resistance against thermal influence, safety aspects are of major interest. The machine tool enclosure must fulfill multiple requirements like retention capabilities against the moving parts of broken tools, lose work pieces or clamping components. In regular use, the noise emission have to be inhibited at the greatest possible extent by the machine tool enclosure. Nevertheless, the loading door and the moving parts of the workspace envelope are interfaces where noise transmission is harder to be avoided and therefore local noise emissions increase. The aim of the objective investigation is to analyse the noise emission of machine tools to determine the local noise transmission of a machine tool enclosure by using arrays of microphones. By the use of this measuring method, outer surfaces at the front, the side and on the top of the enclosure have been scanned. The local transient acoustic pressures have been recorded using a standard noise source placed on the machine table. In addition, an exemplary manufacturing process has been performed to analyse the frequency dependent location resolved sound emissions.
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Soobbarayen, K., S. Besset, and J. J. Sinou. "A simplified approach for the calculation of acoustic emission in the case of friction-induced noise and vibration." Mechanical Systems and Signal Processing 50-51 (January 2015): 732–56. http://dx.doi.org/10.1016/j.ymssp.2014.05.014.
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Mousavi, Seyed Mahmood, and Reza Kamali. "Mathematical Modeling of the Vortex Shedding Structure and Sound Pressure Level of a Large Wind Turbine Tower." International Journal of Applied Mechanics 12, no. 06 (July 2020): 2050070. http://dx.doi.org/10.1142/s1758825120500702.
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The level of noise emission of a circular cylinder, especially a tower of a wind turbine, is remarkably dependent on vortex shedding behind the body of the tower. For these configurations, the key element to reduce noise emission is the upstream flow control of the body. In this paper, the sound pressure level of a wind turbine tower was investigated numerically. In this regard, an in-house OpenFoam solver with Curle’s acoustic analogy was used, and the results were compared with available experimental data, showing proper consistency among them. Then, three passive control methods such as longitudinal slot, splitter plate, and helical strake were applied to control the Kármán vortex shedding behind the tower, followed by the reduction in the level of sound pressure. The results showed that all the above control methods play an essential role in diminishing the fluctuation forces and affect the frequency of vortex shedding. However, the helical strake can lead to the significant suppression of Kármán vortex shedding due to the delay of boundary layer flow separation. Based on the observations, the tower with helical strake reduced the overall level of sound pressure as well as the Aeolian tones in a specific Strouhal number range.
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Denkena, B., B. Bergmann, and H. Blech. "Schadenserfassung auf Radsatzlaufflächen/Defect detection on wheelset treads – Measurement of Magnetic Barkhausen Noise to detect varying workpiece conditions." wt Werkstattstechnik online 109, no. 11-12 (2019): 811–15. http://dx.doi.org/10.37544/1436-4980-2019-11-12-13.
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Unterschiedliche Belastungshistorien von Eisenbahnrädern führen zu Werkstoffveränderungen in der Lauffläche. Diese verursachen sporadisches Werkzeugversagen und verringern so die Prozesssicherheit. Die Messung der Material- und Prozesseigenschaften mit Barkhausenrauschen und Körperschall erlauben, individuelle Bearbeitungsparameter für jedes Exemplar festzulegen. Gezeigt werden die Herausforderungen in der Radsatzbearbeitung, und welche Informationen sich durch die Messtechniken gewinnen lassen. Different load histories of train wheels lead to high variance of material properties on the running tread. Those cause unpredictable tool break and reduce process reliability. The measurement of magnetic Barkhausen noise and acoustic emission allow to gain information of the workpiece and the running process, to find optimal process parameters for the reconditioning of every individual wheel. Typical issues in train wheel machining and results of measurements are presented.
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Yonemura, Shinji, Lin Zhou, and Frank E. Talke. "An Investigation of Slider Vibrations in Near Contact Recording Using a Digital Laser Doppler Vibrometer." Journal of Tribology 125, no. 3 (June 19, 2003): 571–75. http://dx.doi.org/10.1115/1.1540124.
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At a flying height of 10 nanometers, contacts between slider and disk are likely to occur, and control of contact-induced slider vibrations is an important design consideration. In this study, slider vibrations during contact are investigated using a digital laser Doppler vibrometer (LDV). The noise level of the digital interferometer is compared with that of a conventional analog LDV. In addition, acoustic emission (AE) sensors are used to evaluate the contact behavior of the slider. A comparison of AE and LDV data is performed. The results show that the noise level of the digital LDV is lower than that of the analog LDV, and that suspension sway mode vibrations and torsion mode vibrations are excited during contact as a function of the skew angle.
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Karabulut, H., M. Dagli, A. Ates, and Y. Karaaslan. "Results for audiology and distortion product and transient evoked otoacoustic emissions in patients with systemic lupus erythematosus." Journal of Laryngology & Otology 124, no. 2 (October 26, 2009): 137–40. http://dx.doi.org/10.1017/s0022215109991332.
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AbstractThe aim of the current study was to investigate hearing loss and cochlear function in patients with systemic lupus erythematosus, using audiology, distortion product otoacoustic emissions and transient evoked otoacoustic emissions.Study design:Prospective, case–control study.Methods:The study included 26 randomised patients with systemic lupus erythematosus (52 ears) and 30 healthy control subjects (60 ears). Pure tone audiometry was performed at 250 and 500 Hz and at 1, 2, 4, 6, 8, 10, 12, 14 and 16 kHz. Distortion product otoacoustic emissions and transient evoked otoacoustic emissions were measured using Biologic System equipment with Scout Acoustic Emissions System software.Results:The distortion product otoacoustic emission signal responses were significantly different only at 750 Hz, while the distortion product otoacoustic emission signal–noise ratios were significantly different at 750 Hz and 6 kHz (p < 0.05), comparing patients and controls. The transient evoked otoacoustic emission signal–noise ratios were significantly different at 2 and 3 kHz, comparing patients and controls (p < 0.05). The transient evoked otoacoustic emission total signal–noise ratios were significantly different, comparing patients and controls (p < 0.05). In addition, the pure tone audiometry thresholds were significantly different at 250 and 500 Hz and at 1, 2, 10 and 12 kHz, comparing patients and controls (p < 0.05).Conclusion:Our findings do not completely agree with those of previous temporal bone histopathological studies. However, our results do support a general picture of low frequency hearing loss in systemic lupus erythematosus patients. We consider these results to be related to endolymphatic and cochlear hydrops, and we suggest that electrocochleography could be performed in further studies for clarification of this subject.
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Tupov, Vladimir, and O. Matasova. "Calculation of Acoustic Efficiency of Exhaust Silencers for Automotive Internal Combustion Engines." Safety in Technosphere 9, no. 3 (June 10, 2021): 41–47. http://dx.doi.org/10.12737/1998-071x-2021-9-3-41-47.
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Insertion losses as the main characteristic that mathematically describes the acoustic efficiency of a noise silencer has been considered. This characteristic shows the reduction of noise generated by its source, in particular by the internal combustion engine’s exhaust system, at the control point as a silencer use result. Has been presented a mathematical description of the insertion losses, and have been considered parameters necessary for calculating this characteristic. Has been demonstrated the analytical dependence of impedance for the sound emission by the exhaust system’s end hole from the coefficient of acoustic waves reflection by this hole. The performed analysis of the widely used formulas for calculating the coefficient of sound reflection by the end hole has showed their insufficient accuracy for project designs performing. Have been proposed calculation dependences providing high accuracy for calculations of the reflection coefficient modulus, and the attached length of the channel end hole without a flange in the entire range of the existence of plane waves in it. It has been shown that the end correction of this hole at ka = 0 is 0.6127, and not 0.6133, as it was mistakenly believed until now in world acoustics. Has been proposed a method for calculation the exhaust noise source internal impedance. This method more accurately, in comparison with the already known ones, describes the acoustic processes in the internal combustion engine’s exhaust manifold, thanks to increases the accuracy of calculation the silencer acoustic efficiency, that allows develop the silencer at the early stages of the design of an automotive internal combustion engine.
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Zimroz, Paweł, Paweł Trybała, Adam Wróblewski, Mateusz Góralczyk, Jarosław Szrek, Agnieszka Wójcik, and Radosław Zimroz. "Application of UAV in Search and Rescue Actions in Underground Mine—A Specific Sound Detection in Noisy Acoustic Signal." Energies 14, no. 13 (June 22, 2021): 3725. http://dx.doi.org/10.3390/en14133725.
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The possibility of the application of an unmanned aerial vehicle (UAV) in search and rescue activities in a deep underground mine has been investigated. In the presented case study, a UAV is searching for a lost or injured human who is able to call for help but is not able to move or use any communication device. A UAV capturing acoustic data while flying through underground corridors is used. The acoustic signal is very noisy since during the flight the UAV contributes high-energetic emission. The main goal of the paper is to present an automatic signal processing procedure for detection of a specific sound (supposed to contain voice activity) in presence of heavy, time-varying noise from UAV. The proposed acoustic signal processing technique is based on time-frequency representation and Euclidean distance measurement between reference spectrum (UAV noise only) and captured data. As both the UAV and “injured” person were equipped with synchronized microphones during the experiment, validation has been performed. Two experiments carried out in lab conditions, as well as one in an underground mine, provided very satisfactory results.
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Фролов, Виктор Петрович, Галина Ивановна Сокол, and Владислав Юрьевич Котлов. "ВОЛНОВОЙ ПАРАМЕТР КАК КРИТЕРИЙ В ОСНОВЕ МЕТОДА ИССЛЕДОВАНИЯ АКУСТИЧЕСКИХ ИСТОЧНИКОВ ПРИ СТАРТЕ РАКЕТ." Aerospace technic and technology, no. 3 (June 27, 2018): 4–12. http://dx.doi.org/10.32620/aktt.2018.3.01.
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The purpose of this work is to develop a method for determining the types of acoustic sources of radiation and their acoustic fields during the space rockets launch in the first seconds based on the wave parameter values. The main noise source during the space rocket launch is its propulsion system (PS). The cross-section of the nozzle is taken as the oscillation source. The theory of siren sound emission is based on the acoustic power calculation of a jet as a volume sound radiator or a radiator with a space velocity. In the model of a volumetric spherical radiator, the front of a spherical wave is a spherical surface, and the sound rays, according to the definition of the wave front, coincide with the radii of the sphere. As a result of the divergence of waves, the sound intensity decreases with distance from the source. The present work has a prospective character for clarifying the nature of the acoustic fields and for calculating the noise levels from the space rocket launch when designing the cosmodromes. In the requirements for the construction of such structures, the noise impact on the environment of infrasound radiation upon launching launch vehicles is identified. A method for determining the types of acoustic radiation sources during the space rocket launch and their acoustic fields has been developed. The method makes it possible to develop physical models of acoustic fields and apply known mathematical models to calculating their characteristics. The method is applicable for the study of acoustic emissions in the first seconds of the space rocket launch based on the determination of the wave parameter kR and allows us to provide valid data on the levels of sound pressure, intensity and acoustic power at specific points of airspace around the PS in the first seconds of the launch. The character of the acoustic wave radiation from a hole in a specific size gas flue has been studied. To calculate the acoustic characteristics, an algorithm and a program on Java programming language have been developed. Two models of acoustic field generation in the environment are described during the work of a rocket as a plane radiator and spherical waves, depending on the value of the wave parameter kR. A technique for calculating the noise of a remote control in the range for the first 1.5-4 seconds of the space rocket start time is developed
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Hao, Qiushi, Yi Shen, Yan Wang, and Jian Liu. "An adaptive extraction method for rail crack acoustic emission signal under strong wheel-rail rolling noise of high-speed railway." Mechanical Systems and Signal Processing 154 (June 2021): 107546. http://dx.doi.org/10.1016/j.ymssp.2020.107546.
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Abderrahmane, Belkallouche, Tahar Rezoug, and Laurent Dala. "Passive control of cavity acoustics via the use of surface waviness at subsonic flow." Aircraft Engineering and Aerospace Technology 91, no. 2 (February 4, 2019): 296–308. http://dx.doi.org/10.1108/aeat-01-2018-0061.
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PurposeAircraft noise is dominant for residents near airports when planes fly at low altitudes such as during departure and landing. Flaps, wings, landing gear contribute significantly to the total sound emission. This paper aims to present a passive flow control (in the sense that there is no power input) to reduce the noise radiation induced by the flow over the cavity of the landing gear during take-off and landing.Design/methodology/approachThe understanding of the noise source mechanism is normally caused by the unsteady interactions between the cavity surface and the turbulent flows as well as some studies that have shown tonal noise because of cavity resonances; this tonal noise is dependent on cavity geometry and incoming flow that lead us to use of a sinusoidal surface modification application upstream of a cavity as a passive acoustics control device in approach conditions.FindingsIt is demonstrated that the proposed surface waviness showed a potential reduction in cavity resonance and in the overall sound pressure level at the majority of the points investigated in the low Mach number. Furthermore, optimum sinusoidal amplitude and frequency were determined by the means of a two-dimensional computational fluid dynamics analysis for a cavity with a length to depth ratio of four.Research limitations/implicationsThe noise control by surface waviness has not implemented in real flight test yet, as all the tests are conducted in the credible numerical simulation.Practical implicationsThe application of passive control method on the cavity requires a global aerodynamic study of the air frame is a matter of ongoing debate between aerodynamicists and acousticians. The latter is aimed at the reduction of the noise, whereas the former fears a corruption of flow conditions. To balance aerodynamic performance and acoustics, the use of the surface waviness in cavity leading edge is the most optimal solution.Social implicationsThe proposed leading-edge modification it has important theoretical basis and reference value for engineering application it can meet the demands of engineering practice. Particularly, to contribute to the reduce the aircraft noise adopted by the “European Visions 2020”.Originality/valueThe investigate cavity noise with and without surface waviness generation and propagation by using a hybrid approach, the computation of flow based on the large-eddy simulation method, is decoupled from the computation of sound, which can be performed during a post-processing based on Curle’s acoustic analogy as implemented in OpenFOAM.
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Rangwala, S., and D. Dornfeld. "Sensor Integration Using Neural Networks for Intelligent Tool Condition Monitoring." Journal of Engineering for Industry 112, no. 3 (August 1, 1990): 219–28. http://dx.doi.org/10.1115/1.2899578.
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A framework for intelligent sensors in unmanned machining is proposed. In the absence of human operators, the process monitoring function has to be performed with sensors and associated decision-making systems which are able to interpret incoming sensor information and decide on the appropriate control action. In this paper, neural networks are used to integrate information from multiple sensors (acoustic emission and force) in order to recognize the occurrence of tool wear in a turning operation. The superior learning and noise suppression abilities of these networks enable high success rates for recognizing tool wear under a range of machining conditions. The parallel computation ability of these networks offers the potential for constructing intelligent sensor systems that are able to learn, perform sensor fusion, recognize process abnormalities, and initiate control actions in real-time manufacturing environments.
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Algermissen, Stephan, and Hans Peter Monner. "On the stability of decentralized AVC/ASAC for large-scale structures." Journal of Intelligent Material Systems and Structures 28, no. 16 (January 9, 2017): 2255–64. http://dx.doi.org/10.1177/1045389x16682843.
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Promising results have been achieved in controlling vibration and noise emission/transmission of single panel structures using active vibration control (AVC) and active structural acoustic control (ASAC). In most cases the contributed work has focused on a single panel or a section of the fuselage/lining. However, an AVC/ASAC system can only be effective when it is expanded to the entire fuselage structure. This expansion inevitably leads to a large number of sensors and actuators. For model-based control approaches especially, the system identification and the proof-of-stability would be challenging and probably not realizable. In this article a strategy for such large-scale problems is investigated. A decentralized control approach with collocated actuator–sensor pairs is proposed. Since adjacent control loops are highly coupled by the underlying structure, special attention has to be given to the global stability of the entire control system. Instead of proving local stability and setting a global master gain, a method for the tuning of the single collocated control loops is developed that takes the cross-couplings into account. Based on data of DLR’s experimental aircraft Dornier 728, it can be shown that the new method increases the performance of the control system compared to the master-gain method.
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Józsa, Viktor, and Gergely Novotni. "Wavelet analysis of flame blowout of a liquid-fueled swirl burner with quarls." Noise Control Engineering Journal 67, no. 5 (September 1, 2019): 394–403. http://dx.doi.org/10.3397/1/376734.
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Lean swirl combustion is the leading burner concept today, used in several steadyoperating applications to ensure awide operating range and low pollutant emissions. Approaching lean blowout is highly desired by design to achieve the lowest possible NOX emission. It was shown earlier that quarls could significantly extend the operating regime of liquid-fueled swirl burners. In the present study, the accompanying acoustic noise is evaluated by continuous wavelet transformation to show the effect of various quarl geometries on lean flame blowout. However, the desired flame shape of swirl burners is V, first, and a straight flame, and then a transitory regime can be observed before the developed V-shaped flame through increasing the swirl number. If the axial thrust is excessive, blowout might occur in earlier stages. Presently, the characteristic bands before blowout were analyzed and evaluated at various quarl geometries, swirl numbers, and atomizing pressures. The latter parameter also acts as an axial thrust control to adjust the swirl number. firstly, a straight flame, then a transitory regime can be observed before the developed V-shaped flame through increasing the swirl number. If the axial thrust is excessive, blowout might occur in earlier stages. Presently, the characteristic bands before blowout were analyzed and evaluated at various quarl geometries, swirl numbers, and atomizing pressures. The latter parameter also acts as an axial thrust control to adjust the swirl number.
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Ponti, Fabrizio, Vittorio Ravaglioli, and Matteo De Cesare. "Real-Time Processing of Engine Acoustic Emission for Diesel Injectors Diagnostic and Recentering." Journal of Engineering for Gas Turbines and Power 140, no. 9 (May 29, 2018). http://dx.doi.org/10.1115/1.4039751.
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Diesel engine control strategies use complex injection patterns which are designed to meet the increasing request for engine-out emissions and fuel consumption reduction. As a result of the large number of tuneable injection parameters in modern injection systems (such as start and duration of each injection), injection patterns can be designed with many degrees-of-freedom. Each variation of the injection parameters modifies the whole combustion process and, consequently, engine-out emissions. Aging of the injection system usually affects injection location within the cycle as well as the amount of injected fuel (compared to the target value), especially for small pre-injections. Since diesel combustion is very sensitive to injection pattern variations, aging of injectors strongly affects engine behavior, in terms of both efficiency and pollutant emissions production. Moreover, such variations greatly affect other quantities related to the effectiveness of the combustion process, such as noise radiated by the engine. This work analyses the effects of pre-injection variations on combustion, pollutant emissions, and noise radiated by the engine. In particular, several experimental tests were run on a 1.3 L common rail diesel engine varying the amount of fuel injected in pre-injections. Torque delivered by the engine and center of combustion (MFB50) were kept constant using a specifically designed closed-loop combustion controller. During the tests, noise radiated by the engine was measured by properly processing the signal coming from a microphone faced to the engine block. The investigation of the correlation between the combustion process and engine noise can be used to setup a closed-loop algorithm for detecting and recentering injectors' drifts over time.
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Oliveira, Marco A., Luis Bragança, Sandra M. Silva, Dinara Paixão, and Julieta António. "Noise reduction performance of a low energy façade-integrated mechanical ventilator." Building Acoustics, October 25, 2020, 1351010X2096618. http://dx.doi.org/10.1177/1351010x20966185.
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Acoustic comfort and indoor air quality are essential for the health and wellbeing of the occupants of the building. Thus, the façade must guarantee enough sound insulation and ventilation conditions. However, these aspects conflict because opening windows or using ventilation openings reduces the sound insulation of the envelope and allows the exterior noise entrance. To limit noise transmission into the building, ventilators use passive, active or hybrid noise control techniques. This work addresses the noise reduction performance of a mechanical ventilator for façades, evaluating the effect of different options of passive noise control strategies in the sound insulation of the proposed ventilator. In addition, the air change rate and energy consumption of the ventilator were also investigated. Three prototypes were fabricated and tested at an acoustic chamber, along with ventilation tests carried out in a room equipped with a blower door. CFD simulations were used to enhance the aeraulic geometry of the prototypes, prior to its fabrication. The acoustic experiments showed Dn,e,w values up to 55 dB and noise emission levels lower than 25 dB(A). The use of resistive sound absorbers proved to be more effective in mitigating noise than reactive absorbers, over the entire frequency range. The ventilation tests revealed air change rates of 3.7 h−1 at 50 Pa, while the ventilator’s annual energy consumption was 17.52 kWh. The results highlight the proposed device as a viable alternative for decentralised mechanical ventilation, capable of ensuring noise protection and satisfactory ventilation rates, under a sustainable perspective of minimum energy demand.
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Meng, Sheng, Hao Zhou, and Kefa Cen. "Application of the Perforated Plate in Passive Control of the Nonpremixed Swirl Combustion Instability Under Acoustic Excitation." Journal of Engineering for Gas Turbines and Power 141, no. 9 (June 5, 2019). http://dx.doi.org/10.1115/1.4043848.
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Perforated plates are widely used to attenuate noise emission and as acoustic liners in combustion chambers. In this study, the damping performance of the perforated plate located in the combustor inlet section is experimentally and numerically studied. The primary response of nonpremixed swirl flame under 30–400 Hz acoustic excitation with a 445 mm inlet length occurs at 134 Hz and 210 Hz modes. The perforated plate designed for 210 Hz sound absorption with a 328 mm cavity length and an 8.04% porosity is compared to plates with various cavity lengths and different orifice patterns. The acoustic absorption capability of perforated plates is evaluated by the Luong model and tested in an impedance tube. The acoustic measurements show that the sound absorption performance of each plate is strongly affected by the bias flow velocity and cavity length. The combustion results indicate that the installation of perforated plates at the inlet section has two effects: sound attenuation and redistribution of the pressure mode of the combustor. The acoustic mode analysis further demonstrated that, for damping the nonpremixed flame when the combustion instability is caused by the inlet pressure fluctuation, modification of the inlet acoustic mode shape is more efficient than the sound attenuation.
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Westman, Martha R., Daniel B. Putterman, Angela C. Garinis, Lisa L. Hunter, and M. Patrick Feeney. "Wideband Acoustic Reflex Growth in Adults With Cystic Fibrosis." American Journal of Audiology, March 4, 2021, 1–9. http://dx.doi.org/10.1044/2020_aja-20-00117.
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Purpose Individuals with cystic fibrosis (CF) are often treated with intravenous (IV) aminoglycoside (AG) antibiotics to manage life-threatening bacterial infections. Preclinical animal data suggest that, in addition to damaging cochlear hair cells, this class of antibiotics may cause cochlear synaptopathy and/or damage to higher auditory structures. The acoustic reflex growth function (ARGF) is a noninvasive, objective measure of neural function in the auditory system. A shallow ARGF (small reflex-induced changes in middle ear function with increasing elicitor level) has been associated with synaptopathy due to noise exposure in rodent and human studies. In this study, the ARGF was obtained in CF patients with normal hearing, some of whom have been treated with IV AGs, and a control group without CF. The hypothesis was that patients with IV-AG exposure would have a shallow ARGF due to cochlear synaptopathy caused by ototoxicity. Method Wideband ARGFs were examined in four groups of normal-hearing participants: a control group of 29 individuals without CF; and in 57 individuals with CF grouped by lifetime IV-AG exposure: 15 participants with no exposure, 21 with low exposure, and 21 with high exposure. Procedures included pure-tone audiometry, clinical immittance, wideband acoustic immittance battery, including ARGFs, and transient evoked otoacoustic emissions. Results CF subjects with normal pure-tone thresholds and either high or low lifetime IV-AG exposure had enhanced ARGFs compared to controls and CF participants without IV-AG exposure. The groups did not differ in transient evoked otoacoustic emission signal-to-noise ratio. Conclusion These results diverge from the shallow ARGF pattern observed in studies of noise-induced cochlear synaptopathy and are suggestive of a central mechanism of auditory dysfunction in patients with AG-induced ototoxicity.
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Premkumar, S., and K. C. Udaiyakumar. "Numerical Simulation and Design Optimization of Baffle Perforations for Better Noise Reduction." International Journal of Vehicle Structures and Systems 12, no. 3 (October 19, 2020). http://dx.doi.org/10.4273/ijvss.12.3.13.
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An increasing vehicle population always pressurizes to focus on environmental concerns for reduced noise level and harmful emissions. Even though many qualitatively optimized exhaust systems are developed during last two decades, still researchers focus on noise reduction and emission control. Abundant research and development activities are carried out to get a reasonable back pressure drop along with a significant noise reduction in the muffler. The development in computational coding leads to a realistic prediction of flow and acoustic characteristics inside the muffle. Hence the present research work focuses on computational simulation of muffler with single and multi-chambers separated by baffles along with porous pipes. The present work analyses a conventional single baffle muffler configuration and compares the flow behaviour with multi chambers separated by multiple baffle configurations. The shape of the baffle holes is also optimised to get better acoustic performance based on the transmission losses. The flow behaviour and its details are studied inside the muffler to identify the possibility of design improvements. Among the muffler configurations with single and multiple chambers, the overall pressure losses are calculated and compared to get an optimized design with reasonable sound attenuation.
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Afifi, Pretty Omar, Tayseer Taha Tayseer Abdel Rahman, and Ahmed Gamal Khafagy. "Auditory fatigue among call center operators with headset." Egyptian Journal of Otolaryngology 36, no. 1 (October 27, 2020). http://dx.doi.org/10.1186/s43163-020-00044-y.
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Abstract Background To assess whether call center operators are subject to or suffer from any auditory fatigue when compared to normal subjects. A prospective case-control study where twenty-eight call center operators (10 females and 18 males) with an age range from 25 to 46 years and twenty controls (12 females and 8 males) with an age range from 23 to 44 years were included. All call center operators use a headset for up to 8 h daily for a minimum of two consecutive years. Audiological assessments were done to all participants that included pure tone audiometry (PTA), speech audiometry, tympanometry, and acoustic reflexes. Moreover, transient-evoked otoacoustic emission (TEOAE) absolute threshold and distortion product otoacoustic emission (DPOAE) signal to noise thresholds as well as contralateral suppression of TEOAEs and DPOAEs were recorded for both groups. Results There was no significant variation in auditory performances detected with either PTA or OAE (TEOAEs and DPOAEs) test. Besides, there was no statistically significant difference in OAEs (TEOAEs and DPOAEs) with contralateral suppression for both the call center operators and control groups. However, call center operators expressed a feeling of tiredness. Conclusions There was no detectable central or peripheral auditory fatigue experienced by the call center operators when using headsets. However, their sensation of auditory fatigue could be due to cognitive fatigue rather than noise-induced fatigue.
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Sasongko, S., T. Boesoirie, I. Parwati, H. Sastramihardja, and J. Bashirudin. "Effect of Orally Administered Glutathione Peroxidase Mimetic towards Glutathione and Malondialdehyde Blood Level and Otoacoustic Emissions Result in Soldiers with Acoustic Trauma Risk Caused by Howitzer 105 Artillery Weapon BLAST." Asian Journal of Applied Sciences 7, no. 1 (March 18, 2019). http://dx.doi.org/10.24203/ajas.v7i1.5734.
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Excessive noise exposure may cause mechanical and metabolic (oxidative stress) to the inner ear structure (cochlea), resulting in acoustic trauma (TA). Oxidative stress which caused by increasing of free radical ROS/RNS in the organs of Corti, causing apoptosis and necrosis of cochlear hair cell. Oxidative stress was characterized by increasing of malondialdehyde (MDA), decreasing of glutathione peroxidase (GPx) enzyme, and abnormal otoacoustic emission value (refer). Defense mechanism toward oxidative stress was mediated by endogenous antioxidant enyzme (superoxide dismutase/SOD, catalase/CAT, and GPx). Cellular mechanism of glutation peroxidase mimetic was similar as GPx.    Aim of this study was to determine the impact of glutathione peroxidase mimetic to glutathione peroxidase and malondialdehyde level in blood, also otoacoustic emission value on soldiers with risk of TA due to explosion of Howitzer 105 artillery weapon. The design of this study was clinical trial pre and post design, randomized, double blind and placebo controlled, on 34 new recruit soldiers in Artillery Academy of Indonesian Army, during the soldiers were trained to firing Howitzer 105 artillery weapon, from 7th-10th July 2014 in Cimahi and Batujajar. Subjects were divided into 2 groups, the exposure group (group given treatment) and control group. Exposure group was given glutathione peroxidase mimetic (Ebselen SPI 1005) 200mg, orally once daily during the training, meanwhile control group was given. Malondialdehyde and Glutathione Peroxidase level in blood, pure tone audiometry and otoacoustic emission value (DPOAEs) was measured from those two groups, before and after firing training. The data was analyzed using parametric and non parametric, with Number Needed to Treat (NNT, 95%CI) and significance value (p<0.05).    The results of this study showed the number of acoustic trauma events in controle group based on pure tone audiometry test was 23.5%, exposure group was 0%, and based on DPOAEs test the controle group showed 47.1% abnormal/refer, exposure group showed 100% normally/pass, and this difference stastically significance (p<0.051). The group which was given Ebselen SPI 1005 showed increasing 82.4% erythrocyte GPx level (NNT, 95%CI=1.889 [1.159-3.016]; p=0.004), showed increasing 88.2% plasma GPx level (NNT, 95%CI=1.417 [0.970-1.775]; p<0.001), decreasing 100% erythrocyte MDA level (NNT, 95%CI = 2.125 [1.335-3.987]; p=0.01),  showed decreasing 94.1% plasma MDA level (NNT, 95%CI=2.125 [1.29-3.904]; p=0.01), and resulting 100% in normal/pass DPOAEs value (NNT, 95%CI = 2.125 [1.335-3.987]; p=0.01). This study concluded that giving Ebselen SPI 1005 to soldiers with risk of acoustic trauma during the firing Howitzer 105 artillery weapon, increasing GPx level in blood, decreasing MDA level in blood, and resulting normally DPOAEs value (pass)
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"Modified Efficient Protection of Palm Disaster from RPW Larvae using WSNs." International Journal of Recent Technology and Engineering 8, no. 5 (January 30, 2020): 245–51. http://dx.doi.org/10.35940/ijrte.d8158.018520.
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Red Palm Weevil (Rhynchophorus ferrugineus) is the most dangerous and deadly pest to date for coconut, date, sago, oil, and other palms. Because of the dissemble nature of feeding, RPW infestation is detected in the last stage. RPW larvae acoustic activity consists of crawling, chewing, emission and quick oscillating sound. Network of wireless sensor are used to record the sound produced by the Weevil larvae and early stage detection of larvae infestation to coconut tree is conducted using Acoustic techniques. Coconut palm tree is fixed with wireless sensors to receive the sound wave produced by RPW larvae to transmit to server via access points which is capturing the signals from six tree arranged in hexagonal form to process using the Mat lab tools and fundamental frequency of received may also comprise of environment noise. Mel scale in frequency which is nonlinear for spectrum of log power to cosine transform of linear for power spectrum of short term to represent the cepstrum of Mel frequency for processing of received sound. Featured extraction is performed using the Mel Frequency Cepstral. Mel frequency for feature extraction is most used method for feature extraction in frequency domain. Algorithm model of back propagation with neural network of Feed forward are used to enhance the recognize performance. The adopted method is less expensive than current methods of RPW larvae detection. The results in simulation are stimulated in early stage larvae detection and before the damage affect the economic threshold helping the farmers to follow the control measures.
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Schnell, R., J. Yin, C. Voss, and E. Nicke. "Assessment and Optimization of the Aerodynamic and Acoustic Characteristics of a Counter Rotating Open Rotor." Journal of Turbomachinery 134, no. 6 (September 4, 2012). http://dx.doi.org/10.1115/1.4006285.
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The present study demonstrates the aerodynamic and acoustic optimization potential of a counter rotating open rotor. The objective was to maximize the propeller efficiency at top of climb conditions and to minimize the noise emission at takeoff while fulfilling the given thrust specifications at two operating conditions (takeoff and top of climb) considered. Both objectives were successfully met by applying an efficient multi-objective optimization procedure in combination with a 3D RANS method. The acoustic evaluation was carried out with a coupled U-RANS and an analytic far field prediction method based on an integral Ffowcs Williams-Hawkings approach. This first part of the paper deals with the application of DLR’s CFD method TRACE to counter rotating open rotors. This study features the choice and placement of boundary conditions, resolution requirements, and a corresponding meshing strategy. The aerodynamic performance in terms of thrust, torque, and efficiency was evaluated based on steady state calculations with a mixing plane placed in between both rotors, which allowed for an efficient and reliable evaluation of the performance, in particular, within the automatic optimization. The aerodynamic optimization was carried by the application of AutoOpti, a multi-objective optimization procedure based on an evolutionary algorithm, which also was developed at the Institute of propulsion technology at DLR. The optimization presented in this paper features more than 1600 converged 3D steady-state CFD simulations at two operating conditions, takeoff and top of climb, respectively. In order to accelerate the optimization process, a surrogate model based on a Kriging interpolation on the response surfaces was introduced. The main constrains and regions of interest during the optimization were a given power split between the rotors at takeoff, retaining an axial outflow at the aft rotor exit at top of climb, and fulfilling the given thrust specifications at both operating conditions. Two objectives were defined: One was to maximize the (propeller) efficiency at top of climb conditions. The other objective was an acoustic criteria aiming at decreasing the rotor/rotor interaction noise at takeoff by smoothening the front rotor wakes. Approximately 100 geometric parameters were set free during the optimization to allow for a flexible definition of the 3D blade geometry in terms of rotor sweep, aft rotor clipping, hub contour as well as a flexible definition of different 2D profiles at different radial locations. The acoustic evaluation was carried out based on unsteady 3D-RANS computations with the same CFD method (TRACE) involving an efficient single-passage phase-lag approach. These unsteady results were coupled with the integral Ffowcs Williams-Hawkings method APSIM via a permeable control surface covering both rotors. The far field directivities and spectra for a linear microphone array were evaluated, here mainly at the takeoff certification point. This (still time consuming) acoustic evaluation was carried out after the automatic optimization for a few of the most promising individuals only, and results will be presented in comparison with the baseline configuration. This detailed acoustic evaluation also allowed for an assessment of the effectiveness of the acoustic cost function as introduced within the automatic optimization.
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Rao, Prahalad, Satish Bukkapatnam, Omer Beyca, Zhenyu (James) Kong, and Ranga Komanduri. "Real-Time Identification of Incipient Surface Morphology Variations in Ultraprecision Machining Process." Journal of Manufacturing Science and Engineering 136, no. 2 (January 16, 2014). http://dx.doi.org/10.1115/1.4026210.
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Real-time monitoring and control of surface morphology variations in their incipient stages are vital for assuring nanometric range finish in the ultraprecision machining (UPM) process. A real-time monitoring approach, based on predicting and updating the process states from sensor signals (using advanced neural networks (NNs) and Bayesian analysis) is reported for detecting the incipient surface variations in UPM. An ultraprecision diamond turning machine is instrumented with three miniature accelerometers, a three-axis piezoelectric dynamometer, and an acoustic emission (AE) sensor for process monitoring. The machine tool is used for face-turning aluminum 6061 discs to a surface finish (Ra) in the range of 15–25 nm. While the sensor signals (especially the vibration signal in the feed direction) are sensitive to surface variations, the extraneous noise from the environment, machine elements, and sensing system prevents direct use of raw signal patterns for early detection of surface variations. Also, nonlinear and time-varying nature of the process dynamics does not lend conventional statistical process monitoring techniques suitable for characterizing UPM-machined surfaces. Consequently, instead of just monitoring the raw sensor signal patterns, the nonlinear process dynamics wherefrom the signal evolves are more effectively captured using a recurrent predictor neural network (RPNN). The parameters of the RPNN (weights and biases) serve as the surrogates of the process states, which are updated in real-time, based on measured sensor signals using a Bayesian particle filter (PF) technique. We show that the PF-updated RPNN can effectively capture the complex signal evolution patterns. We use a mean-shift statistic, estimated from the PF-estimated surrogate states, to detect surface variation-induced changes in the process dynamics. Experimental investigations show that variations in surface characteristics can be detected within 15 ms of their inception using the present approach, as opposed to 30 ms or higher with the conventional statistical change detection methods tested.
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Sasongko, Sigit. "PENGARUH GLUTATION PEROKSIDASE MIMETIK PERORAL TERHADAP KADAR GLUTATION PEROKSIDASE DAN MALONDIALDEHID DARAH SERTA NILAI EMISI OTOAKUSTIK PADA PRAJURIT DENGAN RISIKO TRAUMA AKUSTIK AKIBAT LEDAKAN MERIAM HOWITZER 105 - Effect Of Orally Administered Glutathione Peroxidase Mimetic Towards Glutathione And Malondialdehyde Blood Level And Otoacoustic Emissions Result In Soldiers With Acoustic Trauma Risk Caused By Howitzer 105 Artillery Weapon Blast." Indonesian Journal of Applied Sciences 5, no. 1 (April 30, 2015). http://dx.doi.org/10.24198/ijas.v5i1.16651.
Full textAbstract:
AbstrakBising impulsif berlebihan mengakibatkan kerusakan mekanik maupun metabolik (stres oksidatif) pada struktur telinga dalam (koklea), sehingga terjadi trauma akustik (TA). Stres oksidatif yang disebabkan peningkatan radikal bebas ROS/RNS di dalam organ Korti, mengakibatkan apoptosis serta nekrosis sel-sel rambut koklea. Stres oksidatif ditandai oleh peningkatan malondialdehid (MDA), penurunan enzim glutation peroksidase (GPx), dan hasil emisi otoakustik abnormal (refer), Mekanisme pertahanan tubuh terhadap stres oksidatif dilakukan oleh enzim anti oksidan endogen (Superoksid dismutase/SOD, katalase/CAT dan GPx). Mekanisme kerja seluler glutation peroksidase mimetik sama dengan GPx. Penelitian bertujuan untuk mengetahui pengaruh glutation peroksidase mimetik terhadap kadar glutation peroksidase dan malondialdehid darah serta nilai emisi akustik pada prajurit dengan risiko TA akibat ledakan meriam Howitzer 105. Rancangan penelitian adalah clinical trial pre and post design, randomized, double blind and placebo controllel, yang dilakukan pada 34 orang prajurit siswa Tamtama baru Pusdik Armed saat latihan menembak meriam Howitzer 105 pada tanggal 7-10 Juli 2014 di Cimahi dan Batujajar. Subjek penelitian dibagi dua, yakni kelompok perlakuan dan kontrol. Kelompok perlakuan diberi glutation peroksidase mimetik (Ebselen SPI 1005) 1x200 mg peroral saat latihan, sedangkan kelompok kontrol diberi plasebo. Kedua kelompok diukur kadar MDA dan GPx darah serta hasil audiometri nada murni dan nilai emisi otoakustik (DPOAEs) sebelum dan setelah latihan menembak. Data dianalisis menggunakan uji parametrik dan non parametrik, dan besarnya manfaat perlakuan dihitung menggunakan Number Needed to Treat (NNT, 95%CI). Kemaknaan hasil ditentukan berdasarkan nilai p < 0,05. Hasil penelitian menunjukkan kejadian TA menggunakan pemeriksaan audiometri nada murni pada kelompok kontrol sebanyak 23,5%, dan pada kelompok perlakuan sebanyak 0%, sedangkan menggunakan pemeriksaan DPOAEs pada kelompok kontrol sebanyak 47,1% abnormal/refer dan pada kelompok perlakuan 100% normal/pass, dan perbedaan ini secara statistik bermakna (p<0,05).Pemberian Ebselen SPI 1005 pada kelompok perlakuan meningkatkan 82,4% kadar GPx eritrosit (NNT, 95%CI=1,889 [1,1593,016]; p=0,004), meningkatkan 88,2% kadar GPx plasma (NNT, 95%CI=1,417 [0,970-1,775]; p<0,001), menurunkan 100% kadar MDA eritrosit (NNT, 95%CI = 1,417 [0,994-1,836]; p<0,001), dan menurunkan 94,1% kadar MDA plasma (NNT, 95%CI=2,125 [1,29-3,904]; p=0,01), serta menghasilkan 100% nilai DPOAEs normal/pass (NNT, 95%CI = 2,125 [1,335-3,987]; p=0,01). Penelitian ini menyimpulkan bahwa pemberian Ebselen SPI 1005 pada prajurit dengan risiko trauma akustik selama pelaksanakan latihan menembak meriam Howitzer 105, meningkatkan kadar GPx darah, menurunkan kadar MDA darah, dan menghasilkan nilai DPOAEs normal/pass. Kata kunci : Ebselen, Emisi otoakustik, GPx, MDA,Trauma akustik.AbstractExcessive noise exposure may cause mechanical and metabolic (oxidative stress) to the inner ear structure (cochlea), resulting in acoustic trauma (TA). Oxidative stress which caused by increasing of free radical ROS/RNS in the organs of Corti, causing apoptosis and necrosis of cochlear hair cell. Oxidative stress was characterized by increasing of malondialdehyde (MDA), decreasing of glutathione peroxidase (GPx) enzyme, and abnormal otoacoustic emission value (refer). Defense mechanism toward oxidative stress was mediated by endogenous antioxidant enyzme (superoxide dismutase/SOD, catalase/CAT, and GPx). Cellular mechanism of glutation peroxidase mimetic was similar as Gpx. Aim of this study was to determine the impact of glutathione peroxidase mimetic to glutathione peroxidase and malondialdehyde level in blood, also otoacoustic emission value on soldiers with risk of TA due to explosion of Howitzer 105 artillery weapon. The design of this study was clinical trial pre and post design, randomized, double blind and placebo controlled, on 34 new recruit soldiers in Artillery Academy of Indonesian Army, during the soldiers were trained to firing Howitzer 105 artillery weapon, from 7th-10th July 2014 in Cimahi and Batujajar. Subjects were divided into 2 groups, the exposure group (group given treatment) and control group. Exposure group was given glutathione peroxidase mimetic (Ebselen SPI 1005) 200mg, orally once daily during the training, meanwhile control group was given. Malondialdehyde and Glutathione Peroxidase level in blood, pure tone audiometry and otoacoustic emission value (DPOAEs) was measured from those two groups, before and after firing training. The data was analyzed using parametric and non parametric, with Number Needed to Treat (NNT, 95%CI) and significance value (p<0.05). The results of this study showed the number of acoustic trauma events in controle group based on pure tone audiometry test was 23.5%, exposure group was 0%, and based on DPOAEs test the controle group showed 47.1% abnormal/refer, exposure group showed 100% normally/pass, and this difference stastically significance (p<0.051). The group which was given Ebselen SPI 1005 showed increasing 82.4% erythrocyte GPx level (NNT, 95%CI=1.889 [1.159-3.016]; p=0.004), showed increasing 88.2% plasma GPx level (NNT, 95%CI=1.417 [0.9701.775]; p<0.001), decreasing 100% erythrocyte MDA level (NNT, 95%CI = 2.125 [1.335-3.987]; p=0.01), showed decreasing 94.1% plasma MDA level (NNT, 95%CI=2.125 [1.29-3.904]; p=0.01), and resulting 100% in normal/pass DPOAEs value (NNT, 95%CI = 2.125 [1.335-3.987]; p=0.01). This study concluded that giving Ebselen SPI 1005 to soldiers with risk of acoustic trauma during the firing Howitzer 105 artillery weapon, increasing GPx level in blood, decreasing MDA level in blood, and resulting normally DPOAEs value ( pass )Keywords : Acoustic trauma, Ebselen, GPx, MDA, Otoacoustic emission