bluuebunny/crossref_metadata_2025 huggingface dataset:
Incoherent Integration of Hyperbolic Frequency Modulated Pulses by the Radon Transform
Authors: Gu Zhaoning , Zhu Chuanqi , Fang Shiliang
Published: February 2023

We herein investigate the incoherent integration of hyperbolic frequency modulated (HFM) pulses for improvement of detection performance under heavy ocean noise. In active sonar systems, combining wideband transmit signals and matched filtering offers considerable processing gain. However,
when relative motion exists between the target and sonar system, the processing gain decreases due to the mismatch caused by the Doppler distortion. As a Doppler invariant signal, the HFM waveform gets the property at the cost of a bias in the matched filter output. We propose an incoherent
pulse integration method based on the Radon transform to take advantage of the property of HFM signals and handle the bias in outputs of matched filters. In the proposed method, return pulses are first matched filtered, and the Radon transform is performed on the outputs afterward. After that,
range bias compensation is performed based on the transform results. The proposed method offers reliable detection performance under heavy ambient ocean noise thanks to the processing gain obtained by both pulse integration and matched filtering. Also, with the help of the Radon transform,
detection, bias compensation, and target parameter (range and radial velocity) estimation could be carried out simultaneously.
Factor analysis of power seat noise using blocked force
Authors: Usui Ryohei , Yoshida Junji , Inose Yasuo
Published: February 2023

In recent years, operating noise generated by various devices in cabin has been focused and becomes noise reduction target due to the reduction of vehicle running noise. In this study, we then conducted the noise evaluation and investigated the noise factors of a power seat at the operating
condition. At first, the operating noise at around driver's ear position and vibration of the seat frame were measured using an artificial head microphones and acceleration sensors. As a result, the noise and vibration at 400-500 Hz band was found to be large and the reduction was essential
to decrease the noise. Subsequently, Component TPA was applied to understand the main factor of the large vibration of the frame at the target frequency. The result shows the vibration was increased largely due to the resonance between the rotational order input force from the driving motor
and the natural frequency of the frame. As an instance of the countermeasure, small weight was added to the resonated part of the frame to avoid the resonance and the vibration and noise was observed to decrease at the target frequency band.
Inter-channel Conv-TasNet for source-agnostic multichannel audio enhancement
Authors: Lee Dongheon , Choi Jung-Woo
Published: February 2023

Deep neural network (DNN) models for the audio enhancement task have been developed in various ways. Most of them rely on the source-dependent characteristics, such as temporal or spectral characteristics of speeches, to suppress noises embedded in measured signals. Only a few studies
have attempted to exploit the spatial information embedded in multichannel data. In this work, we propose a DNN architecture that fully exploits inter-channel relations to realize source-agnostic audio enhancement. The proposed model is based on the fully convolutional time-domain audio separation
network (Conv-TasNet) but extended to extract and learn spatial features from multichannel input signals. The use of spatial information is facilitated by separating each convolutional layer into dedicated inter-channel 1x1 Conv blocks and 2D spectro-temporal Conv blocks. The performance of
the proposed model is verified through the training and test with heterogeneous datasets including speech and other audio datasets, which demonstrates that the enriched spatial information from the proposed architecture enables the versatile audio enhancement in a source-agnostic way.
Runway determination using two-point time difference method
Authors: Higashioka Taichi , Tadahira Yoshio , Sugiura Manabu , Fujita Etsushi , Kohashi Osamu
Published: February 2023

Around airports having multiple runways, aircraft noise affected areas vary depending on the runway operation because the flight path changes by the operation. Therefore, it is important to figure out exactly which runway was used for analyzing the noise impact on the surrounding area.
For this purpose, runway information included in flight data provided by the airport operator can be used in most commercial airports. However, for some airports, the data is unavailable or not always accurate. We developed "Takeoff/ landing runway determination system; DL-TLS" for
determining runway operations and have been utilizing it to aircraft noise analysis. However, that system requires to place measurement stations at the end of each runway to ensure the high level of accuracy. To solve this issue, we focused on difference in acquisition time of the same transponder
signal at two measurement stations. This new approach achieved satisfactory level of runway determination accuracy, by matching the time difference changes with template for each runway. We proved that this method can be used in combination with the current DL-TLS with even higher accuracy.
In addition, we showed the possibility of reducing number of measurement stations and eliminating the measurement location constraint.
Prediction of rattle noise in steering gear system and analysis of contributing factors through neural networks using design and manufacturing data
Authors: Jo Hyeon-Cheol , Seo Jae-Yong , Park Kyung-Hwan
Published: February 2023

In a vehicle, rattle noise may occur when driving on bumpy roads due to clearance between parts of steering gear systems. The rattle noise is perceived by the drivers' ears and it can be the cause of a repair campaign. In order to reduce rattle noise, the dimensions of clearance between
parts are optimally designed. Also, in the development stage, general auto parts companies manage rattle noise below a certain level. However, it is impossible to measure noise for all products at the production stage due to cost and time issues. In this paper, the noise prediction model using
the neural network model for all products based on design factors and the data of manufacturing execution system was introduced. In addition, the main factors contributing to rattle noise were analyzed in the process of creating the model. By referring to the main factors contributing to noise,
it helps in the design of the steering gear to reduce the rattle noise value.
ERP components analysis of selective attention to auditory signals in meaningful or meaningless noise using adaptive correlation filter.
Authors: Tamesue Takahiro
Published: February 2023

Open offices that make effective use of limited space and encourage dialogue, interaction, and collaboration among employees, are becoming an increasingly. However, productive work-related conversation might actually decrease the performance of other employees within earshot more so
than other random, meaningless noises. On the other hands, it is well known that the Event-Related Potential (ERP) in the brain wave elicited by internal or external stimuli are related to the operation of selective attention. The present experiment was designed to determine the effects of
meaningfulness of external noise on ERP in the auditory odd-ball paradigms. First, in order to decide on a template of adaptive correlation filter, multivariate analysis such as the Principal Component Analysis (PCA) for ERP components was performed. Next, performance of algorithm on adaptive
correlation filter for estimating average waveform of ERPs was evaluated. Furthermore, differences in the ERP components due to the meaningfulness of external noise were examined.
Vibration of a metaplate made of an acoustic black hole and local resonators
Authors: Deng Jie , Gausch Oriol , Maxit Laurent , Gao Nansha
Published: February 2023

In recent years, acoustic black holes (ABHs) exhibit fascinating damping effects at mid-to-high frequencies. However, flexural waves having long wavelength cannot be trapped in the ABH pit when there is a residual thickness at the ABH tip, therefore below the cut-on frequency the ABH
effect fails to work. While locally resonant acoustic metamaterials allows mitigating vibrations in subwavelength scale, usually in a narrow band. In this paper we combine the advantages of the metamaterials and ABHs (MMABH) to control vibrations in the whole frequency band. The designed MMABH
plate remains the same weight to the reference uniform plate. To characterize the MMABH performance, an artificial spring component mode synthesis (GECMS) method is suggested, based on the modal coupling between the resonators and the ABH plate via springs. The band gap for the infinite periodic
MMABH and the modes for the finite MMABH have been accurately predicted with the GECMS, compared to a reference FEM model. Numerical results show that the low-frequency peaks of the ABH plate can be substantially suppressed when the resonators with proper loss factor are set at its first resonant
frequency. The proposed MMABH shows great potentials for light-weight and whole-band vibration reduction.
Radiation of a metaplate made of an acoustic black hole and local resonators
Authors: Deng Jie , Guasch Oriol , Maxit Laurent , Gao Nansha
Published: February 2023

In recent years, acoustic black holes (ABHs) have been shown very effective to suppress radiation. However, below the cut-on frequency, the waves cannot be trapped into the ABH. In this paper, locally resonant metamaterials are introduced to the ABH plate to improve the low-frequency
performance. The suggested material is called MMABH. The total mass of resonators is kept the same to the one when fabricating the ABH, such that the lightweight feature still remains valid for the MMABH. Using the Gaussian expansion component mode synthesis (GECMS) method, the band gap and
the coincidences between the MMABH and the air are first characterized, together with the paramagnetic studies of the plate thickness and lattice constant. In what follows, the vibration field of the MMABH is recovered, showing that whole-band reduction can be achieved. The sound pressure,
power and radiation efficiency are next characterized via a discretized radiation model. Likewise, the radiated power is substantially mitigated in the whole frequency range being considered. Finally, the implementation of non-negative intensity (NNI) shows that the sound reduction not only
associates with the outstanding damping capabilities of the resonators and the ABH, but also involves the wave slowdown phenomenon that breaks the coupling with air.
In situ characterisation of exemplary rail vehicle structure borne sound sources
Authors: Böhm Jenny , Brick Haike
Published: February 2023

A narrowband characterisation of structure borne sound sources is needed for an accurate prediction of rail vehicle interior noise. Typical rail vehicle sources are relatively large and heavy structures. In 2019, a measurement method for the indirect determination of the blocked force
was standardised. It can be applied in situ, with the source connected to an arbitrary receiving structure and was found to be promising for rail vehicle applications in recent research projects. One major challenge is the need to measure the coupled velocity and mobility of all relevant degrees
of freedom (six directions per coupling point). Within the European Shift2Rail project DESTINATE, measurements were carried out using a traction motor and an HVAC unit as exemplary sources to investigate the suitability of the in situ method for rail vehicle sources. The measurements include
translational and rotational degrees of freedom. Recently, they were further analysed to investigate the effects of neglecting degrees of freedom. The results will be shown in this contribution.
Prediction of combustion instabilities based on the Green's function in a three-dimensional annular combustor with multiple flames
Authors: Qin Lei , Wang Xiaoyu , Zhang Guangyu , Sun Xiaofeng
Published: February 2023

The prediction of combustion instabilities is essential for modern annular combustors fed by multiple flames. This paper develops a model based on Green's function to study the interaction of multiple flame responses with different types in a three-dimensional (3D) geometry. The flame
responses are described by flame transfer functions and are recognized as monopole sources in 3D cavities. Then the dispersion relation equation in the form of matrix is performed with the condition of equality of pressure. Thermoacoustic complex frequencies, mode structure, as well as the
stability behaviors in combustor can be obtained in this model and the analysis is accomplished using Rayleigh index. The results are compared to the values of existing theoretical models and a good agreement is achieved. Furthermore, the effects of non-identical flame responses on complicated
slanted mode under the condition of asymmetric are studied. In addition, the combustion instabilities of radial mode can be predicted by this model when the radial position distributions of the heat sources move in the case of small ratio of inner wall to outer wall.
In situ characterization of wall linings with perforated facings
Authors: Briere de La Hosseraye Baltazar , Yang Jieun , Hornikx Maarten
Published: February 2023

The in-situ characterization of acoustic materials is one of the main challenges in room acoustics. Previously, the characterization of a single porous layer backed by a hard wall was successfully done by combining pressure-velocity measurements near the surface of the material with
an impedance model fitting approach. In practice however, most porous materials are mounted behind a membrane or a rigid perforated facing. By again combining pressure-velocity measurements and a model fitting procedure, this work studies the possibility to characterize such systems. This
was done by measuring a variety of perforated facings and membrane facings, whether in front of an air cavity or backed by a porous layer and comparing the obtained impedance model parameters to the reference values. Good agreement was observed between the retrieved parameters and the references,
with error in retrieved moving mass, facing thickness, cavity depth, porous layer thickness and porous layer flow resistivity not exceeding 15%.
Practical calibration method of airborne ultrasound measurement system by using acoustic calibrators
Authors: Takahashi Hironobu , Hirano Koto , Yamada Keisuke
Published: February 2023

Airborne ultrasonic apparatus, such as haptic devices and parametric speakers, have been actively developed and are becoming increasingly popular. In order to evaluate the performance of these apparatuses and to assess their safety against exposure to airborne ultrasound, quantitative
sound pressure measurement of the emitted airborne ultrasound is required. Currently, various instruments are used to measure airborne ultrasound. However, since there is no instrument like a sound level meter that integrates the measurement and the display of the measured value, we need to
set up a measurement system and then calibrate the system. For the feasibility of calibration, a system comprising a measurement microphone as specified in IEC 61094-4 and general measuring instruments is more realistic. There are a few possible calibration methods for this system. Considering
the calibration effort and the required accuracy in actual measurement, it is practical to calibrate one specific frequency by an acoustic calibrator and the other frequencies by adopting the relative sensitivity curve of the microphone given by a manufacturer or the specification of the instruments.
The paper discusses the uncertainty when the measurement system is calibrated as described above.
Noise mitigation of UAV operations through a Complex Networks approach
Authors: Siljak Harun , Kennedy John , Byrne Stephen , Einicke Karina
Published: February 2023

This research combines complex systems science, geographical information systems, and environmental noise modelling to analyse effects of future air mobility in urban settings and plan efficient routes for vehicles. The research used the environmental noise maps of an urban agglomeration
produced under the Environmental Noise Directive (END) as input to inform the UAV operations. These maps reveal potential routes for the UAV operations where the noise impact of the vehicle can be embedded within a high background noise due to the existing sources modelled under the END. When
an agent based model is superimposed on a real-world map simple strategies of the diverse agents in interaction with the environment reveal patterns, such as dominant paths, points of congestion, and suggest positioning of terrestrial infrastructure. We investigate how agents can overcome
the conflicts and find trade-off solutions by interacting only with their immediate neighbours-therefore enabling autonomy, decentralization, and putting to use emergent self-organising behaviour. The potential impact of increased drone operations on urban and peri urban regions is significant.
Route optimisation which does not consider the noise is likely to impact on quite areas within our residential spaces and should be considered as part of noise action planning.
High-resolution vibro-acoustic measurement and analysis of the DLR ISTAR aircraft to assess engine-induced cabin noise
Authors: Winter René
Published: February 2023

Aircraft engines, especially when mounted directly to the fuselage, inject a considerable amount of tonal vibrations into the airframe causing audible and comfort reducing cabin noise. Reducing this noise requires the development of specialised noise reduction systems. This is a time
consuming and expensive endeavour. To speed up and ease this process a sufficiently detailed numerical model of the aircraft structure and the force injected by the engines is required. The DLR ISTAR, a Dassault Falcon 2000, was used for an extensive vibration measurement campaign. The goal
of this campaign was twofold: Getting spatially dense information about the aircrafts vibro-acoustic behaviour to later update a finite element model for calculations in the mid-frequency range and to analyse the vibration injected by running engines into the fuselage structure. The measurements
include the vibrational response to both shaker excitation and engine vibration of the DLR ISTAR at about 1400 positions acquired by a rowing grid of sensors. The results are presented in the form of operational deflection shapes and energy transfer paths calculated using structural intensity
analysis.
A Method for Separating Knocking Sounds from Engine Radiation Noise by Deep Learning
Authors: Watabe Hikaru , Kasahara Taro
Published: February 2023

Knocking is the abnormal combustion of a gasoline engine, it generates a metallic noise. Engine knocking can damage the engine, so workers detect knocking by listening to the sound. There is a need to develop a way to automate this kind of work. We developed the deep learning model
which separates Knocking sound from engine radiation noise measured by a microphone. This model obtains the time-frequency mask from the paired data of engine emissions and cylinder pressure. The time-frequency mask enables the separation of knocking sound from engine radiation noise. By training
various rotation speeds, the proposed model can separate the knocking sound without training target engine speed.
Aeroacoustic shape optimization using adjoint sensitivity analysis based on lattice Boltzmann method for bluff bodies
Authors: Kusano Kazuya
Published: February 2023

The present study developed a shape optimization method using adjoint sensitivity analysis based on lattice Boltzmann method to suppress aerodynamically sound generation around bluff bodies. In this method, flow and acoustic fields are directly simulated using the lattice Boltzmann
equation (LBE) with an athermal model under low-Mach-number conditions. The sensitivities of far-field sounds to numerous design variables that define an object shape can be evaluated by solving the adjoint equation, which is derived from the LBE. The adjoint equation can be computed easily
and efficiently, similar to the LBM. The proposed method was applied to the cylinder Aeolian tone, and the cylinder shape was optimized.
Masking effect of sounds during treatment on dental drill sound
Authors: Yamada Tomomi , Nozaki Kazunori , Kuwano Sonoko , Hayashi Mikako
Published: February 2023

A dental drill has influence on acoustic environment in a dental clinic. Sounds of dental drills are temporary varying and have several prominent frequency components in a wide frequency range. Many patients experienced unpleasant feeling with the sound of a dental drill. In Japan,
the use of dental aerosol suction devices, of which loudness level are high, during dental treatment has increased dramatically compared with their use before the COVID-19 pandemic. In this study, the sounds emitted by dental drills and sound related to dental aerosol suction devices were
prepared and psychoacoustic evaluation of the stimuli combined the both noise was conducted. The results may help to improve the discomfort feeling in the dental sound environment.
Effects of traffic speed reduction interventions on noise-induced annoyance and self--reported sleep disturbances: a longitudinal study in Zurich
Authors: Brink Mark , Mathieu Simone , Artho Jürg , Rüttener Stefanie
Published: February 2023

For the purpose of evaluating acceptance and effects of permanent speed reductions on noise level, noise annoyance and self-reported sleep disturbance, we surveyed about 1300 randomly sampled inhabitants, before and after a speed regime changeover from 50 km/h to 30 km/h along 15 small-
and mid-sized city streets in Zurich. Concurrently, individual noise exposure calculations based on traffic counts and on-site speed measurements were carried out. The results show a decrease of road traffic noise levels at the loudest facade point by an average of 1.6 dB during the day and
1.7 dB at night, a significant decrease of road noise annoyance and of self-reported sleep disturbances as well as a significant but moderate increase of the perception of road safety. Most importantly, the exposure-response relationships for annoyance and sleep disturbance were shifted towards
lower effects in the 30 km/h condition by, depending on receiver point, between about 2 and 4 dB during the day and about 4 dB at night, indicating lower effects at the same average level. We conclude that besides the lower average level alone, additional factors related to the lower driving
speed must play a role in the reduction of annoyance and sleep disturbance.
A high-order stabilized finite-element model for the Linearized Navier-Stokes equations
Authors: Olto Simone , Bériot Hadrien , Le Bras Sophie , Denayer Hervé
Published: February 2023

A numerical approach based on high-order stabilized finite elements is proposed to solve thermo-acoustic and visco-acoustic problems accounting for non-uniform mean flow effects. The approach is based on the Linearized Navier-Stokes equations written in conservative form in the frequency
domain. An adaptive polynomial Finite-Element Method (FEM) using hierarchic shape functions is applied for accuracy and ease-of-use. A new enrichment strategy, inspired by the extended Finite Element Method (X-FEM), is developed to resolve the finer scales near the walls at a reasonable computational
cost. It relies on a re-orthogonalization procedure proposed to preserve both the continuity of the solution and the conditioning properties of the discrete model. The performance of the method is first evaluated by performing two-dimensional simulations of acoustic waves affected by visco-thermal
wall losses and mean flow effects while propagating in a duct. Numerical results are in good agreement with the analytical solution. The applicability of this new methodology is then demonstrated by computing the sound absorption of an acoustic liner installed in an impedance tube in the presence
of a grazing flow in 2D. Numerical predictions of the sound pressure levels in the tube are compared to experimental data from the literature.
Applying Spanish Acoustic Regulations to mechanical ventilation with heat recovery systems. Case study.
Authors: Carrascal García Teresa , Romero Fernández Amelia , Casla Herguedas Belén
Published: February 2023

Due to recent changes in IAQ (Indoor Air Quality) and energy efficiency requirements, MVHR (Mechanical Ventilation with Heat Recovery) has become increasingly common in Spanish new build dwellings. Regarding acoustics, Spanish Decree RD 1367/2007 sets out limits for sound pressure levels
due to building services and describes the noise measurement and assessment procedure, which applies also to ventilation noise. The assessment procedure consists of a series of measurements of different noise parameters and then the calculation of corrections due to tonal, low frequency and
impulsive components. This paper shows an example of a MVHR fan unit installed in the ceiling of a common dwelling, where some measurements were performed. Based on these measurements, this paper discusses the noise measurement and assessment procedures and proposes some improvements for the
Spanish acoustic regulations. In addition, it also analyses the available calculation methods (ASHRAE and VDI 2081) and their application to comply with Spanish requirements.
Prediction methodology and assessment of low frequency noise break-in for a science building
Authors: Karatsovis Christos , Quaranta Erika
Published: February 2023

More often than not the effects of anthropogenic (or man-made) noise are evident in all facets of the built environment: from residencies and offices through to state-of-the-art R&D facilities. Often external ambient noise can penetrate the fabric of these buildings and adversely
affect, for instance, human symbiosis on a socio-political level or mar the outcome of advanced technological research in scientific facilities. The principles of acoustic design of buildings are mainly limited to a specific frequency range, i.e. within the standard sonic range, and usually
do not account for the effect of lower frequency noise, such as sound in the less audible range (infrasound). It is in the remit of this work to outline a practical method of estimating the impact of lower frequency noise on a science building housing particularly sensitive experiments susceptible
to infrasound. An analytical model of the excitation mechanism of the external building fabric will therefore be outlined and used in tandem with a structural/acoustical numerical model of a science building in order to predict the low frequency acoustic levels within the labs. A set of measured
noise data in the actual labs will also lend a level of support to the described method of predictions.
Numerical investigation of power flow input into a fuselage due to jet engine induced wing vibrations
Authors: Zettel Sebastian , Winter René , Norambuena Marco , Böswald Marc
Published: February 2023

The wings of passenger aircrafts are constantly vibrating due to various loads. There are transient low-frequency vibrations caused by gust loads. But there are also higher-frequency vibrations caused by the vibration load of the jet engines. The higher-frequency stationary vibrations
of the wing are partially introduced as a power flow into the fuselage and radiated there as sound, which is then perceived as noise. In this work, which is part of the EU CleanSky2 framework, this chain of effects is being investigated in more detail aiming for the quantification of the vibrational
power flow input into the fuselage by utilizing structural intensity. In this paper, numerical investigations are carried out on FEM models of an Airbus A320 wing generated with a parametric model generator. First, the structural components mainly responsible for the power transmission are
identified, and second, the magnitude of the power input into the fuselage is determined in dependence of the pylon position along the wing. The engine vibrations are approximated by a custom-developed model. In the further course of the project, these numerical results will be validated by
a test campaign. For this purpose, a real wing of an A320 is available as a test structure.
LOWNOISEPAD: Low-cost noise control by optimized rail pad: Feasibility study on the use of rail pad as noise mitigation measure
Authors: Verhelst Eduard , Yilmazer Pinar , Oertli Jakob , Dinhobl Guenter
Published: February 2023

When aiming to minimize track noise, there is a significant conflict of aims that must be considered. Tracks with stiff rail pads are generally less noisy than ones with soft rail pads. Stiff rail pads, however, can decrease the long-term quality of the track. In order to achieve an
optimum, beside stiffness also rail pad damping at relevant frequencies must be considered. The International Union of Railways (UIC) works with its members to better understand the noise-generation and rail pad effects. The LOWNOISEPAD project brings together the European railway community
in an effort to find an optimal rail pad for both noise and track quality issues and for the different situations encountered in 12 European railway networks. Besides acoustic rail roughness, the stiffness and damping properties of rail fastening systems such as rail pads have a considerable
influence on rail noise. In practice, rail pad design is always a compromise between track engineers' demand for flexibility and acoustic engineers' expectations for sufficiently high Track Decay Rate. The paper describes the measurements undertaken in the project, shows first conclusions
as well as a software tool that allows determining noise levels after installing rail pads with given stiffness and damping properties.
Using data-driven techniques to provide feedback during material characterisation
Authors: Gaborit Mathieu , Jaouen Luc
Published: February 2023

The aim of the work is to study the feasibility of using machine learning techniques to design a decision helper to assist the characterisation of acoustic materials (porous media for instance). The tool is intended to alert the human operator about specific physical phenomena occurring
during the measurements or common mistakes in handling the characterization rig or its parameters. Examples of classical issues include leakage around the samples, unintentional compression during the sample mounting, errors in input parameters such as the static pressure or temperature, etc.
The proposed helper relies on a physical analysis and a k-nearest neighbours classifier using the Fréchet distance to score the measurements. This approach allows to measure the similarity between curves, independently from sampling. The training phase is performed on a labelled dataset
created from actual impedance tube measurements and possibly some computer generated results to bridge gaps. The inputs are frequency-dependent quantities including normal sound absorption curves, surface impedance, dynamic mass density and dynamic bulk modulus.
Piezoelectric vibration suppression of a flexible mounting link for precise space robot operating
Authors: Li Feng , Hu Lanqing , Zou Huaiwu
Published: February 2023

In large-range manipulator operating mission, it is essential to connect an additional link with end-effectors to enlarge the operation space, which unavoidably introduces the vibration disturbance. An active piezoelectric vibration suppression method is proposed in this paper. The
multiple piezoelectric patches shunted with time-variant resonant circuit are mounted on the link and an adaptive controller acting on circuit is utilized for suppressing the vibration due to excitation on various mass on the tip of the link during the robot operating. The electro-mechanical
system of a kinematic manipulator model and an analytical flexible link model is established. The vibration controller is designed using the neural network which maps the relationship between the output voltage of piezoelectric sensors and the proper impedance of the circuit. The simulation
study shows that the proposed method in this paper could be well applied in space robot operating.
An ocean acoustical ray-tracing tool based on Fermat's least time principle in real a environment
Authors: Gonçalves João Duarte
Published: February 2023

Recently the Underwater Acoustics Modelling and Sonar Prediction - SeaRider tool was developed by the Portuguese Naval Academy. Based on Fermat's least-time principle, 2D and 3D models of propagation of acoustic rays in the ocean were developed. These models consist of an algebraic
differential system of equations. In this work we considered additionally the possibility of calculating the trajectory, addressing the occurrence of acoustic ray reflections either on the water surface or on the ocean floor. The reflections in the boundaries were assumed specular and were
modelled based on Snell's law. We also considered the possibility of calculating the trajectories, taking into account the actual data of the speed of sound in the ocean as well as the bathymetry of the bottom. For this purpose, the 2D and 3D ocean-acoustic ray tracing developed can use existing
data bases (GEBCO, NOAA, WOD18 and TEOS-10), extracting information onthe topography and climatology to compute the acoustic ray trajectories in a real environment. This tool allows us, for example, to identify positions of ecosystems subjects to the effects of different sources of noise.
The developed algorithms were submitted to several numerical simulations and compared with other ocean-acoustic modelling programs.
Subwoofer array design for optimal performance and minimal noise pollution in the Roman theatre of Italica, Spain
Authors: Kopplin Claus , Gomez-Agustina Luis , Grilo Bensusan Alvaro
Published: February 2023

Subwoofer arrays are widely used in live sound events. However, the performance of sound systems and the generated environmental noise pollution in the vicinity of Roman theatres is not well researched and documented. The investigation aimed to determine the most suitable subwoofer
array configuration for an outdoor Roman theatre according to their low frequency coverage across the audience area and overspill on nearby residential areas. Performance suitability was determined by measuring the overall sound pressure (dBA) and spectrum levels of the arrays within the audience
area at several locations representative of nearby residential areas. The Array Performance Rating (APR) was calculated for each array configuration to complement performance assessments. Results showed a notorious difference between coupled and uncoupled arrays, as well as between ground-based
and flown subwoofer configurations. It was proven that the flown point source array offered overall less sound pressure levels and spectral variability in the audience plane and it caused the least environmental noise pollution. The conclusions drawn from this study can provide valuable guidance
applicable to future sound system deployments and reconstruction projects of ancient outdoor theatres of similar architectural and environmental characteristics.
The new buildings acoustic classification scheme in Spain: the standard UNE 74201
Authors: Romero Fernández Amelia , Carrascal García María Teresa , Casla Herguedas María Belén
Published: February 2023

In September 2021, the document that develops an acoustic classification scheme was approved in Spain. It is the UNE 74201 standard that is described in this paper. The Spanish ACS is applicable to new and existing buildings for private or public residential use, for health/hospital
and educational use. The development of this document has been a challenge which, requested by the construction sector, has been completed after 5 years of collaborative work, within the Technical Committee CTN74/SC2 - Building Acoustics of the Spanish Standardisation Body, UNE. It's been
achieved an ACS compatible with the "DB HR" Spanish building acoustics regulations and, in turn, in agreement as much as possible with ISO/TS 19488:2021. The standard defines different levels of noise protection by using a system of six classes for the requirements, A to F, where
Class D defines the minimum requirements for acoustic quality that are mandatory to fulfil in the building code. Criteria for airborne, impact and façade sound insulation, for service equipment noise and for reverberation time are included. This paper shows in detail the verification,
sampling and class assignment procedures developed in the standard. A comparison of the most general aspects with other European schemes is also shown.
An experimental investigation into the influence of installed passively controlled jet flows on wall-pressure fluctuations
Authors: Carbini Edoardo , Lawrence Jack , Proença Anderson , Meloni Stefano , Camussi Roberto
Published: February 2023

Jet-surface interaction(JSI) represents a significant noise problem in the installation of modern ultra-high bypass ratio turbofan engines. The use of chevron nozzles is known to reduce low-frequency jet mixing noise(JM) by increasing the velocity gradient in the jet shear layer. This
effect is expected to influence the jet flow in the vicinity of the wing and to modify the jet-surface interaction noise. To clarify the physics of these two(JSI and JM) noise source mechanisms, an extensive experimental investigation has been conducted in the anechoic chamber of the Doak
Laboratory at the University of Southampton. Various measurements were carried out on an isolated subsonic jet and an installed beneath a 2D NACA4415 airfoil using different nozzle shapes and passive vortex generator geometries. The wall-pressure field on the airfoil surface was investigated
using a set of wall-pressure transducers flush-mounted in the streamwise and spanwise directions on the pressure side of the airfoil. The unsteady wall-pressure data were analysed in both time and frequency domains to assess changes in: 1) surface trailing edge spanwise correlation length,
2) streamwise convection velocity of the hydrodynamic pressure field, and 3) modification of the hydrodynamic pressure field in the vicinity of the surface trailing edge.
Experimental and Numerical Studies on the Hilbert Fractal Architecture as an Acoustic Metamaterial
Authors: Comandini Gianni , Ting Valeska , Azarpeyvand Mahdi , Scarpa Fabrizio
Published: February 2023

Experiments and numerical methods were used to investigate the key parameters which affect the transmission loss behaviour of Hilbert fractal acoustic metamaterials. The tests were conducted using a four-microphone impedance tube, and the numerical simulation was performed using COMSOL
Multiphysics software. Fractal order and cavity slot widths on Hilbert fractal metamaterials were investigated. 3D printing manufacturing techniques were used to make polylactic acid specimens. The COMSOL model developed utilised thermo-viscous and lossless domains with boundary layer mesh
in the fractal cavities. The tests and simulations' frequency range were 0.2 kHz to 3.0 kHz, with parametric gap widths ranging from 0.5 mm to 3.0 mm. There is a reasonable agreement between the numerical models and the experimental results; the second-order Hilbert fractal had the most significant
effect on transmission loss, with an experimental peak of nearly 50 dB around 1600 Hz. Moreover, multiple transmission loss peaks were observed as a function of the gap width in the five Hilbert fractal orders studied. The gap width is one of the critical parameters for optimising the performance
of the Hilbert fractal as an acoustic metamaterial.
Low-frequency vibration of a timber joist floor section connected by metal screws: experimental validation of FEM models
Authors: Shen Xiaoxue , Hopkins Carl
Published: February 2023

The structural dynamics of a timber floor junction (six pieces of chipboard plate screwed to a single timber joist) have been investigated experimentally in a frequency range up to 200Hz. Experimental Modal Analysis (EMA), transfer mobilities and velocity level ratios between the chipboard
walking surface and the joist were measured with 12 or 24 screw connections between the joist and the chipboard. These experimental data were used to validate Finite Element (FE) models that focussed on the interaction between the chipboard and the joist due to the screws. The aim is to develop
validated FE models for timber floors that can be used to assess heavy impacts (such as the rubber ball impact source) and act as a reference for the future development of TSEA models for lightweight structures. The screws were modelled using both rigid connections and springs. For the latter,
each point connection was modelled by four springs with stiffness (three coordinate directions and one rotational direction), with model updating using a Deep Neural Network (DNN). A comparison of mode frequencies and mode shapes from EMA and FEM will be made along with forced vibration of
the structure.
Monitoring of combustion oscillation by cascade extended state observer
Authors: Wang Zhaohui
Published: February 2023

In modern gas turbines, active control has proved to be a useful tool in the suppression of combustion oscillation. As the basis of early warning and control, signal monitoring will directly affect the performance of the whole system. Traditionally, time series analysis and machine
learning methods are often applied to monitor system information. However, there are some drawbacks, such as a large amount of calculation, limited accuracy and insufficient generality, which limit the engineering application. To solve these problems, this paper presents a monitoring method
based on extended state observer (ESO), which utilizes the observed derivative information for online monitoring. Due to the difficulty in parameter tuning and sensitivity to noise, conventional high order ESO is modified to cascade low order ESO. Meanwhile, a compensation scheme based on
Taylor expansion is proposed to tackle the phase delay caused by the cascade group. Combined with known system information, the structure of ESO can be further updated, which improves monitoring accuracy. Simulation results show that the proposed method can achieve computation simplicity,
high monitoring accuracy, and has great robustness and noise immunity.
Listening effort for sentence comprehension in noisy classroom: the mediating role of linguistic factors, inhibitory control and noise sensitivity
Authors: Visentin Chiara , Prodi Nicola , Pellegatti Matteo , Garraffa Maria , Di Domenico Alberto
Published: February 2023

Children learn in noisy classrooms, where often the main masker is their own babble. Even when the acoustic conditions are favorable (i.e. low noise levels), differences in individual performance and listening effort in complex academic tasks are observed. Personal characteristics such
as linguistic and cognitive skills, and sensitivity to noise have been reported as factors supporting students' performance. Moreover, the Framework for Understanding Effortful Listening (FUEL) postulates that the additional individual dimension of children's motivation should be considered
when evaluating listening effort besides task-related cognitive demands. This study aims to explore the interplay of the above-mentioned individual factors for primary school children (N=120, grades 3 to 5) doing a sentence comprehension task in a two-talkers background noise. Data on both
accuracy and response time, as well as self-ratings of effort and motivation were acquired. In addition, inhibitory control, linguistic competences and self-ratings of noise sensitivity were measured in quiet. Results first highlight how acoustic conditions and linguistic competencies influence
child's motivation, and then show how the child's inhibitory control and noise sensitivity mediate behavioral and subjective effort. Thus, individual factors shall be taken into consideration when evaluating the effect of classroom acoustics on the performance in academic tasks.
The dependence of transformer sound power measurement accuracy on microphone configurations in the anechoic chamber.
Authors: Kozupa Michal , Kamiński Filip , Baranski Robert , Wszolek Tadeusz , Pawlik Pawel
Published: February 2023

The paper is aimed at investigating the number and location of microphones required to accurately calculate the sound power level of a harmonic noise source. The measurement procedure performed is based on the IEC standard for the determination of transformer sound power level. The
current procedure defines numerous measurement points around the tested transformer. Reducing the number of measurement points could significantly speed up the measurement procedure when a transformer is tested during the manufacturing process. Within the research work, estimations on the
number and location of measurement points are identified to accurately calculate sound power level. The approach is tested and validated using specially developed software in LabView, that allows inclusion or exclusion of measurement points from the sound power level calculations. To prevent
harmonic wave interference, acoustic wave reflections and background noise, the measurement procedure took place in the anechoic chamber.
Modeling the Influence of Under-Sleeper Pads on the Vibration Emissions from Railway Traffic
Authors: Mahlert Nils , Hermann Sascha
Published: February 2023

One of the aims of the European research project FINE-2 is to contribute to reducing noise and vibrations caused by railway traffic. In this context, the development of models describing the influence of relevant parameters on the excitation of train-induced vibration emissions were
investigated in WP 8 "Ground Vibration" which is led by DB Systemtechnik. Here, resilient track components and especially under-sleeper pads were considered by a new modelling approach. Dependent on the dynamic stiffness of the relevant superstructure components, the model is based
on the German standard DIN 45673-4, which describes an approach to compute the insertion loss of under-ballast mats by using an impedance model. The paper will show a general description of the model, the steps taken to adapt the existing model to consider under-sleeper pads instead of under-ballast
mats, as well as results validated by using existing measurements.
A Boundary Element Method (BEM) Solver for Low Frequency Room Modes
Authors: Cicero Andrea , Hargreaves Jonathan A.
Published: February 2023

Room modes are known to be problematic in small critical listening environments. They degrade the acoustic quality at low frequencies, producing peaks and nulls in the frequency domain and ringing in the time domain. The Finite Element Method (FEM) is currently the easiest way to predict
such resonances for arbitrarily shaped rooms. This solves for mode frequencies and shapes, as well as Q-factors and decay rates. Such 'eigenfrequency' solvers are commonplace in FEM, but FEM has the disadvantage of needing to mesh the entire air volume in the room. The Boundary Element Method
(BEM) avoids this and only requires a simple boundary mesh, but solution of its eigenfrequency problems is much more challenging and appears in only a few academic papers. Here we transfer those approaches to Room Acoustics. We implement the block Sakurai-Sugiura method, which uses a contour
integral in the complex frequency plane to convert the BEM eigenfrequency problem, which is usually non-linear in wavenumber, into a standard linear eigenfrequency problem that is straightforward to solve. The method is demonstrated through application to a cuboid room and an irregularly shaped
room, both with impedance boundary conditions. Results are validated against FEM and discussed.