bluuebunny/crossref_metadata_2025 huggingface dataset:
Energy Management Strategy for P1 + P3 Plug-In Hybrid Electric Vehicles
Authors: Zhang Bo , Shi Peilin , Mou Xiangli , Li Hao , Zhao Yushuai , Zheng Liaodong
Published: December 2023

In order to simultaneously improve the fuel economy and overall performance of plug-in hybrid electric vehicles (PHEVs), this study selected the P1 + P3 configuration as its research object. Through a configuration analysis of hybrid vehicles, it confirmed the feasibility of P1 + P3 configuration-PHEV operating modes. Based on this, a rule-based control strategy was developed, and simulation models for the entire vehicle and control strategy were constructed in both Cruise and MATLAB/Simulink software. The study conducted simulation analysis by combining three sets of Worldwide Harmonized Light vehicles Test Cycle (WLTC) driving cycles to assess the fuel-saving potential of the dual-motor P1 + P3 configuration. The simulation results showed that the vehicle model was reasonably constructed and the proposed control strategy had good control effects on the entire vehicle. Compared to conventional gasoline vehicles, the P1 + P3 configuration PHEV achieved a 67.4% fuel economy improvement, demonstrating a significant enhancement in fuel efficiency with the introduction of electric motors.
Walls in office building ended against ceiling plate - measured sound insulation
Authors: Larsen Bernt Mikal
Published: December 2023

In Norway there are many experiences with office buildings with measured R'w around 32-37 dB between offices. Such values of sound insulation are measured for situations were the walls are ended against the ceiling, and not splitting the ceiling on both sides of the wall. In office
building in Kristiansand with 40 mm Thermatex Silence (Dn,f,w 44 dB) as ceiling plate and walls ended against the ceiling, measured sound insulation between offices was R'w 41-45 dB. The reason for these good results is due to good sealing between wall and the ceiling plate of mineral wool.
Experience from other situations with low sound insulation for such solutions, seems basically to be explained by sound leakage in the connection between wall and ceiling plate. It will be possible to achieve measured sound insulation between offices with walls ended against ceiling of mineral
wool of at least R'w 40 dB or better, with good enough sealing between wall and ceiling and a good enough ceiling plate.
Theoretical analysis of conversion process of tire tread vibration to road noise exciting force
Authors: Ishihama Masao
Published: December 2023

Tire tread vibration due to unevenness of the road surface, through some process, acts on the axle, which is the excitation source of solid-borne components of road noise. However, this conversion process has not been fully understood until now. Therefore, the author decomposed it into
two parts and analyzed it theoretically. They are: a) variations in cavity pressure, b) variations in sidewall contact angle with the wheel rim. As a result, it is now possible to formulate the relationship between tread displacement/velocity and the force acting on the axle. This study enabled
us to calculate the effect of these two processes on a typical tire shape, size and pressure.
Vibration behaviors of orthogonally stiffened cylindrical shell coupled with internal circular plates in wavenumber-frequency domain
Authors: Wu Duoting , Su Jinpeng , Hua Hongxing
Published: December 2023

In this paper, vibration characteristics of orthogonally stiffened cylindrical shell coupled with multiple internal circular plates are discussed using wavenumber analysis. The theoretical model and formulation for the orthogonally stiffened cylindrical shell coupled with internal circular
plates are developed by employing a modified variational method. A unified variational modeling procedure is employed to ensure the continuity conditions between each substructure, including cylindrical shell, circular plate, longitudinal stringer, and circumferential ring. The displacement
components of the cylindrical shell are described by Fourier series along the circumferential direction and orthogonal polynomials along meridional direction. Thus, the responses of the shell in wavenumber domain can be naturally obtained. Convergence studies for the theoretical model are
conducted by finite element method to verify the reliability of the present method. The vibration behaviors of the coupled model under three typical external loads, including single point force, multiple uniformly spaced point forces, and line force, are studied based on the vibration fields
in wavenumber domain. The results indicate that the circumferential modal coupling effect and modal contribution to the total vibrations are sensitive to the types of external excitations, which induces the different vibration behaviors.
Comparison of sound emission in ASJ RTN-Model 2018 and several European prediction models
Authors: Okada Yasuaki , Yoshihisa Koichi
Published: December 2023

The road traffic noise prediction model ASJ RTN-Model 2018 is used widely as a support tool in the environmental impact assessment of development projects in Southeast Asia as well as in Japan. In European countries, various prediction models such as Nord and CNOSSOS-EU have been published.
Since 2018, the specific noise emission, which can be incorporated into CNOSSOS-EU, was proposed in several countries: CNOSSOS-NL, -FR and sonROAD. Also, the coefficients of the emission model in CNOSSOS-EU were replaced in 2021. In this study, the values of noise emission and its frequency
characteristics were compared between these prediction models using immission values calculated considering the effects of the ground surface and a barrier. The results revealed that the emission values for three vehicle types in ASJ RTN-Model 2018 are almost 1 dB lower on average than those
in European models, and the immission values on the reflective ground are independent of differences in the frequency characteristic between the emission models.
Geometrical influence of structures in close proximity to a railway wheel on its sound radiation
Authors: Zhang Xianying , Bai Xubo , Thompson David , Squicciarini Giacomo
Published: December 2023

The most important noise source from railways is rolling noise. It is produced by vibration of the track and wheel, which is induced by their combined surface roughness at the wheel/rail contact. The component of noise radiated by the wheel is generally often the greatest above 2 kHz.
The current models used to predict the sound radiation from the wheel consider this to be in free space; in practice, however, the rail beneath the wheel, the ground in close proximity and the bogie frame around it have geometrical effects on the wheel radiation. This paper investigates their
influence in terms of the sound power and the directivity at 7.5 m from the track center. The sound radiation of a single wheel in free space is analysed first by using the combination of vibration finite element method and acoustic boundary element method in 3D. The geometry of the rail and
ground beneath the wheel are then introduced and their effects on the wheel radiation are predicted. The bogie frame is also introduced to find its influence on the sound radiation from the wheel.
Frequency domain adaptation of multichannel active road-noise sound control system with virtual sensing
Authors: Elliott Stephen J. , Vered Yoav
Published: December 2023

The convergence speed of multichannel adaptive active noise control algorithms can be improved by pre-whitening the reference signals and reducing their cross-correlations. When considering nonstationary processes, like road noise, it proves advantageous to use a short time-based cross-correlation
estimation of the reference signal, which can be obtained as part of the bin-normalised frequency domain least-means-squares algorithm. However, the regularisation of such an algorithm is crucial to its success and can further improve the convergence rate. In addition, virtual sensors can
be employed by using the additional filter method, which provides targets for the measured error signals to follow, generated from the reference signals. Still, the performance of this virtual sensing is known to be degraded if the properties of the reference signals change, so special consideration
should be taken when the reference signals are nonstationary.
A theoretical study of self-soise generation in turbulent jets using one-dimensional turbulence and Lighthill's acoustic analogy
Authors: Sharma Sparsh , Ayton Lorna , Klein Marten , Méndez Juan A. Medina
Published: December 2023

Modeling and simulation of turbulent jet noise is an ongoing numerical challenge relevant to noise pollution control. In the present study, the concept of a novel dimensionally reduced modeling approach based on the so-called one-dimensional turbulence model (ODT) is discussed. ODT
aims to resolve source terms due to velocity and kinematic pressure variations in the acoustic near-field at all relevant scales, but only for a single physical coordinate. In the standalone formulation of the model, the physical coordinate taken as a notional line of sight that is pointing
in radial cross-stream direction and advected downstream with the axial velocity of the jet while the microscales evolve. Thereby, turbulence is represented by a stochastically sampled sequence of discrete mapping events that punctuate the deterministic molecular diffusive advancement. It
is discussed how an ensemble of small-scale resolving independent flow realizations can be used to estimate turbulent noise sources from a range of scales. The main objective is to present an approach for the prediction of broadband self-noise generated by a turbulent jet using ODT and Lighthill's
equation. Dedicated experimental measurements are conducted for verification and validation of the numerical modeling approach.
Indoor-outdoor method for measuring building noise reduction
Authors: Sharp Ben H. , Cox J. Eric , He Hua
Published: December 2023

Recent research has resulted in the development of a new SAE Recommended Practice (ARP 6973) for measuring building noise reduction in determining the eligibility of aircraft noise impacted structures for participation in FAA-funded Airport Sound Insulation Programs. The SAE ARP follows
methods previously described in ASTM E966 by requiring an external loudspeaker and measurement of the difference between the exterior and interior noise levels, but has a special focus on aviation noise applications and provides detailed guidelines for practitioners working in the field. Like
the methods described in ASTM E966, the SAE ARP 6973 method require the application of adjustment factors to the exterior noise level measurements to account for the reflection of sound energy from the façade surface. However, there are situations encountered in the field, such as areas
with limited exterior space, where it is either difficult to place a loudspeaker, or to generate a uniform distribution of sound energy over the building facade. In an attempt to overcome these limitations, an alternative method for measuring noise reduction is described, where a loudspeaker
is placed inside the house and the noise reduction measured from inside to outside, eliminating the need for any adjustments to the measured levels, and removing restrictions on the placement of an external loudspeaker.
Integrated aircraft noise data processing at Narita International Airport
Authors: Kondo Kentaro , Nojiri Yasufumi , Hasegawa Osamu , Shinohara Naoaki
Published: December 2023

In the area around Narita International Airport, the relevant local governments and Narita International Airport Corporation (NAA) have set up aircraft noise monitoring stations to continuously monitor and measure aircraft noise in order to confirm compliance with the Environmental
Quality Standards of Aircraft Noise, to respond to complaints from residents, and to study noise control measures. The measurement data are aggregated and processed by Narita Airport Regional Symbiosis Promotion Foundation (NSF) from a centralized and neutral standpoint, and the results are
released to the public after deliberation and verification by a third-party organization established at NSF. This paper introduces NSF's unprecedented efforts to centrally aggregate and process measurement data from monitoring stations installed around the airport. Keywords: Aircraft Noise,
Data Processing
Sound radiation from a cylindrical shell in an underwater waveguide
Authors: Kha Jamie , Karimi Mahmoud , Maxit Laurent , Skvortsov Alex , Kirby Ray
Published: December 2023

Sound radiation from cylindrical structures immersed in an underwater acoustic waveguide, that is, a fluid layer with an upper free surface and lower rigid floor, is a challenging engineering problem to analyze due to the complex interaction of the radiation from the excited structure
and its subsequent propagation within an acoustic waveguide. To contribute to the understanding of this phenomenon, an analytical model is presented. The model involves an infinitely-long three-dimensional cylindrical shell that is point-excited and submerged in a perfect underwater waveguide,
where the reflections off the free surface and rigid floor have no absorption. The equations of motion of the shell are given by thin shell theory with heavy fluid loading. The image-source method is applied directly to the acoustic boundary conditions to account for the vibroacoustic coupling
of the shell and waveguide. Together, these techniques combine into an analytical framework that can evaluate both the vibration of the shell and its acoustic radiation. Results include the far-field radiated sound pressure with observations of the relative and combined effect of the waveguide
boundaries.
Loss-induced multiple modal coalescences in an acoustic ring cavity
Authors: Liu Tuo , Shi Tongyang
Published: December 2023

Chiral exceptional points refer to a class of non-Hermitian degeneracies where two counter-propagating whispering-gallery-like eigenmodes coalesce into one travelling eigenmode, which have been utilized to create orbital angular momentum in various wave systems. However, most studies
in this field have so far focused on the modal coalescence for a specific azimuthal order. In this work, we investigate the eigenmodes evolution of an acoustic ring cavity under complex spatial modulation of refractive index along the azimuthal direction. We show that a careful engineering
of the complex modulation, possibly realized with acoustic metamaterials, can lead to multiple modal coalescences to produce a series of travelling eigenmodes with different orbital angular momentum orders. These coalesced eigenmodes can be directly excited by a simple source at their resonant
frequencies. Our work provides a straightforward approach to the generation and manipulation of acoustic orbital angular momentum.
Field measurement of ground effect for road traffic noises
Authors: Sakamoto Shinichi , Zhang Xinyi , Yonemura Miki
Published: December 2023

In ASJ RTN-Model 2018, which was proposed by the Acoustical Society of Japan, a practical calculation method of the ground effect in A-weighted overall level for road traffic noise is specified by relatively simple formulae. The method is derived from the solution of the ground effect
based on wave theory. By the practical calculation method, the attenuation level by the ground effect for a relatively long distance between the source and receivers tends to become larger on softer ground. Especially in the cases of lower sound source positions as specified in the ASJ RTN-Model
2018, the excess attenuation becomes large. To investigate the appropriate treatment of the ground condition in the case of road traffic noise propagation on soft ground, the authors have performed a field measurement of road traffic noise. The measurement results were compared with calculation
results by both the ASJ RTN-Model 2018 and the theoretical solution based on the wave theory. From the comparison, the features of the propagation characteristics obtained by the ASJ RTN-Model 2018 were discussed.
How the bundengan string material affects its musical sound
Authors: Parikesit Gea Oswah Fatah , Aulia Fadhil , Kusumaningtyas Indraswari
Published: December 2023

Bundengan is a traditional musical instrument from Wonosobo Regency, Central Java, Indonesia. Bundengan consists of several main components, namely the kowangan resonator, a set of loaded strings, and a set of bamboo bars. Bundengan can imitate the sound of the percussive elements in
gamelan lengger Wonosobo, such as gong, kempul, kenong and kethuk. This research aims to analyze the impact of the choice of bundengan string material on the frequency spectrum and temporal dynamics of the sound produced by the bundengan. Quantitative data is obtained by measuring the acoustical
signal produced by each bundle string that is tested. Our data indicates that the natural gut badminton string is the most suitable string for the sound of gong, kempul and kethuk, with errors of 1.87 cents, 23.88 cents, and 0.88 cents, for the sound of gong, kempul, and kethuk, respectively.
Meanwhile, the solid core badminton string with single wrap is the most suitable string for kenong, with an error of 3.29 cents. The data also shows that the natural string gut has the most suitable damping factor to produce the sound of the gong, with a damping factor of 0.036.
Noise by neighbours: an update
Authors: Poll Ric van , Simon Sendrick
Published: December 2023

RIVM conducts an annual survey of residents' perceptions of their living environment. This includes monitoring data on residents' perception of noise, odours and vibrations. Between 2019 and 2022, more than 8,000 Dutch residents aged 16 and over took part in these surveys. Online questionnaires
presented people with a range of possible sources of annoyance and sleep disturbance in their homes and neighbourhoods. Road traffic noise is a major source of severe annoyance and sleep disturbance. Mopeds and motorcycles in particular cause severe noise annoyance. Compared to 2016, more
people experience severe annoyance from the sound of vans. Road traffic also causes annoyance through vibrations. Neighbours are the second most important source of noise annoyance and the most important source of severe odour annoyance in the Netherlands. The latter is mainly due to odours
from fireplaces, fire pits and barbecues. Neighbours' activities also cause severe annoyance due to vibrations.
Review of Japanese PERS pavements by Yokohama and Nipponroad in Japan: Our challenge and withdrawal
Authors: Fujita Hitoshi , Izawa Katunori
Published: December 2023

A Porous Elastic Road Surface (PERS) is a pavement using rubber chip, fine aggregate and polyurethane. Its acoustical absorption characteristics and flexibility make it a superior low noise pavement compared to porous asphalt pavement. In Japan, Yokohama Rubber and Nipponroad were engaged
to develop an on-site construction type of PERS. During this development many difficult problems needed to be solved, especially de-bonding problems between PERS and the base layer. Finally, we could develop PERS which showed 10 dB noise reduction and more than 3 years life span. There was
also the European PERS project named PERSUADE, but the life span of the pavements tried there were only 1-2 years. In this paper, field test result are presented and the difference between Japanese PERS and PERSUADE PERS are discussed. At present, Japanese PERS R&D activites have come
to end. We hope our experiences will be help for the future development of low noise pavement. Please take note that construction of PERS in Japan was made by other organizations too, which is not treated here.
Experimental studies on the effect of ceiling materials on the sound environment of underpass concourse using the station simulator
Authors: Yonemura Miki , Sakamoto Shinichi , Tomizawa Hideo , Ishiwata Yasuhiro , Nakazawa Shiniji , Arai Yuko , Hamaguchi Masayoshi , Takahashi Akihisa
Published: December 2023

Sound environments in railway stations are often noisy because of sound-reflective materials and many noise sources. Especially in underpass concourses, structure-borne sounds are radiated from the ceiling due to vibrations when trains pass by. This results in a high noise level, which
often interferes with listening to the announcements. In this study, to examine interior materials that effectively reduce such noise in railway stations, the following measurements and laboratory experiments were carried out: 1) Field measurements of vibrations of the ceiling and environmental
sound in stations in Tokyo. 2) Reproduction of vibrations and sounds in the station simulator (full-scale mock-up of a station building), under the four different types of ceilings. 3) Auditory tests to evaluate the noisiness of train passing sounds and environmental sounds, using reproduced
sounds in the station simulator as test sounds. As a result, the ceiling with damping material was effective for structure-borne sound, while the ceiling with porous sound-absorbing material was effective for air-borne sound. This result suggests that it is important to consider the placement
of ceiling materials according to the noise situations.
Proposal of guideline for the development of announcement at a railroad station in Japan with consideration for an elderly people
Authors: Tsujimura Sohei
Published: December 2023

In Japan, the birthrate is declining, and the population is aging rapidly. It is estimated that the percentage of the population aged 65 and over will reach about 38% by 2065. The use of railroads by the elderly will increase in the future. For smooth transferring at railroad stations,
it is necessary to acquire not only visual information but also audio information. Hearing levels tend to decline with age, and the elderly are more likely to have difficulty acquiring audio information than younger people. For reasons such as improved safety and convenience of platforms and
concourses, diversification of information provided to railroad users, and the necessity to provide an environment that considers various types of disabilities, it is desirable to provide easy-to-hear voice information to all users. Especially for the elderly, station announcement is one of
the most effective support methods for guiding and directing them along routes that are becoming increasingly complex. In this paper, the author comprehensively summarizes the results of research on control methods for station announcements at railroad stations for an aging society and proposes
a guideline for the development of announcement at railroad stations from the perspective of universal design.
Quantification of noise levels for the flying drones in accordance with operating condition
Authors: Park Dong-Chae , Ahn Ok-Cheol , Kim Jun-Young , Kim Yong-Hee , Kim Sang-Ho , Lee Seung-Soo
Published: December 2023

This study investigated quantification method of drone noise levels according to various operating conditions through the field measurements. In South Korea, a pilot credential is mandatorily required to operate a drone more than 250 g in accordance with the Aviation Safety Act. Pilot
credentials are divided into 4 levels, and Type 1 credential is the highest grade for covering drones of 25 kg to 150 kg which are high-risk unmanned aerial vehicles. For the pilot credential test, a standard flight pattern is defined with various operating conditions such as taking-off, landing,
hovering, cruise, triangular and circumferential flights. Accordingly, the environmental noise characteristics according to the standard flight pattern were measured for two types of drones. The measurements are carried out at three points which are 5 m apart from the center of the basic operational
range, and one point which is 2 m apart from the center of the route passing-by during the cruise operation. As results, the appropriate evaluation indicators and measurement points were suggested by each operating condition. In addition, repeatability and reproducibility of the measurement
results were discussed, and the relationship with environmental noise standards was reviewed.
Experimental characterization of road roughness input for tyre dynamics simulations
Authors: Paglia Ivano La , Rapino Luca , Ripamonti Francesco , Corradi Roberto , Baro Simone
Published: December 2023

In the framework of road vehicle noise and vibration assessment, the experimental evaluation and the synthesis of artificial road surfaces are typically used for vehicle dynamics simulations and for the estimation of passengers' ride comfort. Indeed, besides the tyre/road interaction
and the dynamics of the specific tyre, the road input represents a fundamental aspect for the prediction of the vehicle NVH (Noise, Vibration, Harshness) performances. Moreover, to perform complete simulations of specific environmental conditions, tyre models and road surfaces must be properly
combined. In this context, tyre manufactures rely extensively on Finite Element Modelling (FEM) to carry out sensitivity analyses on design parameters. To account for the tyre dynamics in the frequency ranges of interest, very refined meshes are used and, therefore, tyre footprints are modelled
as interface surfaces with a significant number of nodes in contact with the ground. To properly run tyre dynamics FEM simulations, this paper proposes a methodology for the experimental evaluation of a road surfaces. Measurements are carried out by means of lasers and a dedicated linear rail
system. The Power Spectral Density of the road vertical profile is estimated and, eventually, the road surface was generated by means of a dedicated algorithm.
Component-wise regression sound source models for the aircraft noise prediction framework J-FRAIN
Authors: Takaishi Takehisa , Kobayashi Tomohiro , Ikuta Yuho , Imamura Taro
Published: December 2023

In this study, we created sound source models for a newly developed simulation framework named 'J-FRAIN' that can accurately predict the time histories of noises from each major aircraft noise-generating component at ground observation points during the landing approach phase. Sound
source distributions of more than twenty types of jet transport aircraft have been measured in flight using a microphone array deployed under the final approach path to an airport. In this paper, the Boeing 787-8 is presented as an example for modeling. The sound powers of each aircraft component
- engines, landing gear, and high-lift devices - were calculated quantitatively from the domain integration of the measured acoustic maps. Then, component-wise regression sound source models were created based on the relationship between engine rotational speed, airspeed, and deployment angle
of high-lift devices. The models were implemented in the 'J-FRAIN' simulation framework that integrates a sound propagation model. The predicted time histories of ground noise were compared with measurement results from a single microphone placed at the center of the microphone array, and
were found to be in good agreement.
Experimental investigation of road surface parameters affecting tire/road noise
Authors: Koike Hiroshi , Ushiro Kosuke
Published: December 2023

It is known that tire/road noise is strongly affected by the properties of the road surface such as its profile and sound absorption coefficient. Several parameters, represented by mean profile depth (MPD), have been proposed or standardized as surface profile parameters, but none of
them clearly explains the relationship with tire/road noise generation. This study attempted to identify a new surface parameter that correlates more closely with tire/road noise. Surface profile measurements and close proximity (CPX) measurements were conducted on several road surfaces with
different properties on test tracks. Tire P1, the reference tire for the CPX method, and two types of passenger car tires were used for the CPX measurements. According to our experience, the variation of the peak height of the road surface with distance is closely related to the excitation
input to the tires and thus noise generation. Therefore, we devised a road profile parameter to quantitatively evaluate the variation of peak height. A relatively strong correlation was observed between this parameter and the CPX level. The validity of this parameter will be verified by further
measurements on general roads in the future.
Prediction of wind turbine noise: Comparison of three standardized prediction methods
Authors: Evensen Karen Brastad , Gjestland Truls , Kokowski Piotr , Libiszewski Paweł , Kaczmarek Tomasz , Gałuszka Michał
Published: December 2023

Noise from wind turbines seems to be relatively more annoying than noise from other sources. Yet wind turbines are considered important for the shift to renewable energy sources. In the planning process of new wind farms, it is important to accurately predict the noise impact on nearby
communities in order to minimize noise conflicts. Noise from an existing 2 MW wind turbine has been measured in a number of positions under various wind conditions. The results have been compared with predictions using sound propagation modules according to ISO 9613-2, CnossosEU and Nord 2000.
The work is part of the ongoing Polish-Norwegian research project HETMAN, Healthy Society towards optimal management of wind turbine noise. The actual results presented in this paper should therefore be considered preliminary.
Employing the maximum likelihood fitting method in the principle of probability and statistics to continually apply the original FHWA road traffic noise prediction model
Authors: Zhang Jiping
Published: December 2023

The original federal highway administration (FHWA) model for road traffic noise (RTN) prediction in the United States (US) has been widely applied in many countries. However, the condition was that the intensities of vehicle noise sources at the reference distance must be determined
based on the empirical formula related to vehicle speed and road surface obtained by applying the measured results of a large number of different vehicles in the US. Because the dominant vehicle types and road pavement structures in other countries are not the same, the classification of vehicles
and the calculation formula for the source intensity will be different. Even in the US, because of the older modeling data, the current vehicles and their changed noise source, and the new traffic noise model (TNM), the original FHWA model may produce errors if applied in other countries.
Therefore, by employing the maximum likelihood method in probability and statistics, this study proposes a method that can continue to directly apply the original FHWA model according to the local vehicle traffic flow, together with a simple method of measuring the attenuation of RTN with
distance, to eliminate the uncertainty of the source intensity.
Underwater radiated noise from a submerged cylinder: measurements in far and near field conditions
Authors: Decaux Matthieu , Hugues Florian , Leclère Quentin , Maxit Laurent , Meyer Valentin , Carbonell Cédric
Published: December 2023

Measurements of radiated pressure from a cylinder hull immersed in water are of interest for naval research. Generally, the far-field pressure pattern in a wide frequency range is required. We compare the direct measurement of the far-field underwater noise generated by a vibrating
cylinder submerged in a large dock to the far-field prediction obtained via near-field measurements of the same structure in a reverberant tank. Both measurements require advanced signal processing to minimize the impacts of undesired factors such as low signal-to-noise ratio or with disturbing
echos. The results associated with both environments are confronted and provide general guidance to evaluate the radiated sound power.
Design of an instrumentation system for assessing the acoustic attenuation performance of ducted Helmholtz resonators in the presence of grazing flow
Authors: Xue Rong , Mak Cheuk Ming , Cai Chenzhi , Ma Kuen Wai
Published: December 2023

The Helmholtz resonator (HR) has been widely used as a duct silencer to reduce low-frequency noise. However, the presence of grazing flow could influence the noise attenuation performance of the HR in ductwork systems. This study aimed to design an instrumentation system for studying
the acoustic attenuation performance of ducted HRs in the presence of grazing flow. The instrumentation system includes a centrifugal fan, diffusion section, anechoic termination, flow development section, test section, and sound source. In this study, a HR as a ducted silencer was installed
in the test section of the instrumentation system. Transmission loss (TL) due to the HR insertion was measured in the presence of forward and reverse grazing flows. The results showed that the instrumentation system succeeded in assessing the noise attenuation performance of the HR under a
high sound pressure level and different flow rates and directions.
Measurement system for harmonic source noise directivity definition, based on phase correlation in multimicrophone configuration
Authors: Kozupa Michał , Baranski Robert , Wszołek Tadeusz , Pawlik Paweł
Published: December 2023

The paper is aimed at describing the measurement system for noise propagation of strictly harmonic noise source like electrical transformer. The system consists of fourteen microphones with phase calibration, equally spaced around the tested object in three distances. Electrical transformer
is source of stationary and harmonic noise creating acoustic filed with many phase interactions. This acoustic wave correlations create positive and negative phase interference in the acoustic near field called also reactive field. The described measurement system can define the wave front
for every frequency emitted by the source, thus allows to analyze the phase interference in the acoustic field. The phase interference comes from noise propagation of the transformer tank having complex vibration deflection shapes. The study and results allow for better understanding and definition
of the critical distance for the reactive acoustic field created by multi-harmonic noise sources like transformers.
Numerical investigation of communicating turbulent boundary layers through porous media
Authors: Hunter Thomas P. , Doan Nguyen Anh Khoa , Avallone Francesco , Ragni Daniele
Published: December 2023

The reduction of trailing edge noise can be achieved through the use of porous trailing edges. It has been found that the unsteady interaction between the suction and pressure side of the airfoil is of relevance for noise reduction. Therefore, this study aims at investigating such ow
physics. The proposed numerical setup consists of two vertically stacked temporally developing channel ows (4 ˇ (2 + t) ˇ 4, where and t are the half-charnnel height and the porous medium thickness respectively). The ow eld is solved using the lattice Boltzmann method through PowerFLOW.
The two channel ows communicate through a fully resolved porous medium. In this work, the porous medium is a 75% porous Schwarz' P triply periodic minimal surface. Results show span-wise coherent turbulent structures developing on both sides of the porous medium. This is consistent with previous
work on turbulent channels over porous media which enable ow in the stream-wise direction. However, the communication between both turbulent boundary layers results in these span-wise structures to be out-of-phase on either side of the permeable material. This phenomenon occurs at a frequency
range where the noise reduction of porous trailing edges is the highest when compared to previous studies. A shift in turbulent kinetic energy carrying scales, with more energy being present in larger scales, is also observed. It can be concluded that this would increase the likelihood of
interference occurring in the various locations of hydrodynamic pressure uctuation scattering and as such increase the noise reduction of porous trailing edges.
Multizone sound field reproduction based on equivalent source decomposition
Authors: Du Bokai , Yan Qun
Published: December 2023

Multizone sound field reproduction attempts to recreate a desired sound field on the bright zone and reduce sound field energy on the dark zone. Conventional pressure-matching based multizone reproduction method is only able to control sound pressures at limited number of measurement
points on the bright zones which are equal to target sound field recording points number. The reproduction performance is strongly affected by the number of recording points. In this paper, a reproduction method based on the sparse plane wave decomposition method is proposed to improve the
reproduction performance when the target sound field is generated by one or a small number of sources. The recorded target sound field is decomposed into a group of plane waves. Loudspeaker weights are calculated as a summation precalculated corresponding plane waves weights. A simulation
is conducted in a room to verify the performance of the proposed method. Compared with the conventional method, the proposed method achieves better sound field reproduction accuracy on the bright zone and similar acoustic contrast performance.
Numerical investigation on the mechanism of cascade unsteady force control based on pre-stator actuated oscillating trailing edge flaps
Authors: Tang Wanghao , Shi Shuaikang , Huang Xiuchang
Published: December 2023

Unsteady force caused by rotor - stator interaction is one of the main excitation sources of impeller machinery vibration. To suppress the unsteady force, the stator wakes are conducted by the secondary flow generated by stator actuated oscillating trailing edge flaps (AOTEF). The unsteady
Reynolds averaged Navier-Stokes equation (RANS) method based on the shear transport turbulence k-ω model and the improved delayed detached eddy simulation (IDDES) method are employed to numerically study a single cascade with AOTEF. The results show that the AOTEF oscillating phase angle
determines the phase relationship between the stator wake and the rotor blade, and then affects the strength of the interaction between the stator wake and the rotor blade. Under the optimal phase of AOTEF, the rotor unsteady force decreases by 3 dB at rotor-stator blade passing frequency.
The AOTEF significantly rises the peak value of the stator wake deficit. The amplitude of stator wake vorticity is significantly weakened by AOTEF, and the vortex shedding phase is regulated by AOTEF actuating phase. This study provides a new idea for the vibration and noise reduction of turbomachinery.
Simulation Research on Active Noise Control in Turboprop Cabin with Complex Sound Field Environment
Authors: DONG Ningjuan , YAN Qun , HOU Feng , XUE Qing
Published: December 2023

This article summarizes the research work on the complex sound field environment in the cabin of a certain turboprop aircraft, the construction of multi-channel noise active control system and the verification of noise reduction effect were carried out. On the basis of spectrum analysis
and distribution characteristic analysis of the measured data in the cabin of this turboprop, taking the key peak frequency as the target frequency, a multi-channel noise active control system with 16 inputs and 16 outputs that meets the requirements of noise reduction indicators is built.
And a comprehensive verification platform for the noise reduction effect of turboprop aircraft similar to the real environment was built in a semi-anechoic chamber to verify the real environment was built in a semi-anechoic chamber to verify the noise reduction effect of the system. The result
show that the system can reduce the sound pressure level at key frequencies by 14.9 dB(A), the system noise reduction effect is significant and effective.
Sound attenuation analysis of a honeycomb structure with extended necks
Authors: Laly Zacharie , Mechefske Christopher , Ghinet Sebastian , Ashrafi Behnam , Kone Charly T. , Atalla Noureddine
Published: December 2023

In this paper, a honeycomb structure metamaterial consisting of 95 necks that are attached to the perforated top panel is presented and its sound absorption coefficient and transmission loss are investigated using the finite element method. Helmholtz resonators are therefore created
by each honeycomb cell (cavity) and the attached neck, which is protruding within each cell. The structure has therefore a high bending stiffness due to the honeycomb mechanical performance and constitutes a sound absorber based on the parallel assembly of multiple Helmholtz resonators. This
study demonstrates the importance of properly designing the diameter and the length of each neck to create a broadband sound absorption. One resonant sound absorption peak is observed when all the necks are identical, and two absorption peaks are obtained using two different sets of neck parameters.
When the number of different necks increases, the sound absorption frequency band improves and when the parameters of all the necks are different, resulting in a parallel assembly of 95 different Helmholtz resonators, the sound absorption frequency band broadens. The material design studied
in this paper can be useful in various applications where available space is limited and high mechanical stiffness and noise reduction are required in one structural element.
Implementing Construction Noise Mitigation Management Framework to Achieve Quiet Building Demolition in Urban Environment of Hong Kong: A Case Study on Demolition of a Multi-storey Carpark Building
Authors: LEONG Ka-long Karen , WONG Mei-ch , KWOK Kwun-ting Chris , WONG Chor-kuen, Alfred , NG Tsz-wai, Jason , WONG Wai-keung, John
Published: December 2023

Hong Kong is a compact city. Construction noise impact from noisy construction activities such as building demolition work in urban areas, if not properly handled, could easily arouse concern from neighbouring residents. Tremendous efforts in planning and implementation of noise mitigation
measures are usually required for developing infrastructure projects in Hong Kong. The Central Kowloon Route project was one of the mega projects to construct a 4.7 km long trunk road across urban districts in Hong Kong. Under this project, a Multi-storey Carpark Building, which was built
atop an existing heavily trafficked flyover and situated in a densely populated area with less than 20 m away from the nearest high-rise residential building, was required to be demolished atop the existing flyover without interfering its operation or causing unacceptable noise impact to the
nearby residents. This paper presents the successful implementation of the construction noise mitigation management framework of the Central Kowloon Route project to achieve quiet demolition of the Multi-storey Carpark Building, including the relevant Construction Noise Mitigation Measure
Plan, Contract Specifications on adopting quieter measures and Community Engagement Plan. The paper also analyzes the actual noise performance of the quieter measures adopted and nearby public responses when the demolition of the carpark building is actively pursuing.
Aeroacoustic analysis of a bass-reflex loudspeaker using LES: Validation of 2D and 3D numerical model with experiment
Authors: Tabata Ryoya , Uchida Katsuya , Okada Yuko , Honji Yoshikazu , Takahashi Kin'ya
Published: December 2023

A bass-reflex loudspeaker has a port that amplifies low frequencies through Helmholtz resonance. However, high sound pressure levels can cause fluid flow near the port tip, leading to noise and distortion. Two-dimensional axisymmetric aeroacoustic analysis is commonly used to predict
these non-linear phenomena; however, it has been reported to overestimate harmonic distortion. Presently, its accuracy has not been adequately verified through three-dimensional simulations or comparison with experimental results. This study validates the numerical model by comparing results
from three- and two-dimensional analyses with experimental measurements on a straight tube port axisymmetric speaker model. In aeroacoustic analysis, large-eddy simulations are adopted, and the speaker model is acoustically driven at the Helmholtz resonance frequency. The results show that
while the two-dimensional axisymmetric model overestimates the harmonic distortion and noise in the frequency response of far-field sound pressure, the three-dimensional model agrees well with the experiment up to the band where the harmonic distortion and port noise appear. This indicates
that three-dimensional aeroacoustic analysis is necessary to accurately reproduce the fluid-induced distortion and noise of a bass-reflex port speaker.
How many languages can be broadcast simultaneously as an emergency announcement?
Authors: Sato Hayato , Morimoto Masayuki , Sato Hiroshi
Published: December 2023

In spaces where people from various countries come and go, voice guidance is often broadcast sequentially in multiple languages. However, this method is disadvantageous to users of the language broadcast later, and this problem can be particularly severe in evacuation broadcasts. In
addition, the broadcast time may be too long, which may increase the annoyance/noisiness and spoil the soundscape. We propose the use of simultaneous multilingual broadcasts as a challenging method of achieving language barrier-free and saving the time required for information transmission.
In the present study, we examined how many languages can be broadcast simultaneously to clarify the feasibility of the method. The intelligibility of simultaneous broadcasts of up to four languages (Japanese, English, Chinese, and Korean) was examined through listening experiments. Participants
were instructed to write down Japanese speech only. The experimental parameters were the arrival direction of the target/distracting speech and the background noise level. The results of the experiments suggested that broadcasting two languages simultaneously is sufficiently practical, and
even three languages can be practical under certain conditions.
Review on Current Applications of Metamaterial in Hong Kong Noise Control and its Potential Application in Construction Sites
Authors: CHONG Stephen Wai Tung , CHAN Silver Cheuk Kiu , CHAN Edward Siu Leung , LEUNG Joe Cho Shing , LEE Chee Kwan , TSANG Terence Sai Wing , MAK Ho Yiu , CHOW Tsz Pong , CHEN Shuyu , YANG Min
Published: December 2023

During the past few years, construction works for infrastructure and housing developments in Hong Kong have been brisk with economic growth. There are nearly two construction sites in every square kilometer of our limited urban/built-up land. Hence, noise from construction works is
one of the major concerns to our community. Striking a balance between ever-tightening construction programme and quieter living environments is crucial to support our sustainable development. Typical construction noise control pinned on using noise barriers for meeting both noise standards
and rising public expectations. However, conventional material of noise barriers cannot effectively address and reduce construction machinery noise with a characteristic spectrum under various engineering constraints, e.g. loading, space, construction time and cost, etc. Recently, an emerging
technology, acoustic metamaterials, takes a new approach that allows optimization of noise reduction targeting the characteristic spectrum within the said constraints. This paper will briefly introduce the principle of acoustic metamaterial and its current applications in noise control industries.
Perspective applications of acoustic metamaterial for construction noise control and the potential benefits will also be discussed.