1,721,045 research outputs found
Analysis of Sound Propagation in Lined Ducts and Parallel Baffle Silencers
No full textA test campaign was carried out, by means of an experimental apparatus compliant with EN ISO 11691 and EN ISO 7235, with the aim to determine the acoustical attenuation produced by several lined ducts and parallel baffle silencers, varying both the geometry and the physical properties of the sound-absorbing material.
A second experimental campaign was carried on, by means of a standing wave tube, to study the effects of confinement on the acoustical properties of porous sound-absorbing materials. The data obtained showed consistency with the data found in the literature, i.e. that over a specific percentage open area of the perforated facing, equal to about 20%, the facing itself is "transparent" to the sound and has the only behaviour of a mere support of the sound absorbing material.
This information has been useful in order to avoid the modelling of the perforated facings in the comparative study developed to analyze the behaviour of a finite element model versus two of the most widely used theoretical methods to estimate the noise attenuation in lined ducts, from Sabine and Kurze.
A commercial silencer (FCR series SQ-A model 110-600) of known performance was tested in the above mentioned test facility and later modelled by means of FEM and Sabine’s and Kurze’s theories for a frequency range from 125 Hz to 8000 Hz: the numerical approach has been found to be the best choice to tackle the problem of the study of sound propagation in rectangular ducts, compared to the high cost of field surveys and experiments or to the poor and nowadays inadequate accuracy of existing analytical methods
Obtaining .3tx files from almost any elevation source using VTBuilder
No full textPeople using the "INM" software may find VTBuilder useful for obtaining .3tx files from almost any elevation source
A multi disciplinary approach for harbour noise pollution reduction: The report project
No full textWithin the framework of the Interreg initiative, funded by the European Regional Development Fund, the cross border programme Italy-France Maritime 2014-2020 aims to achieve the goals of the EU 2020 Strategy in the Northern Mediterranean area by promoting smart, sustainable and inclusive growth. In particular, the specific object of the axis 3 - lot 2 of the programme is the improvement of the sustainability of commercial ports and logistics platforms to reduce noise pollution. The project "REPORT - Rumore E PORTi" seeks to realize a joint multidisci-plinary study, acting as a link between the other twin projects (LIST Port, DECIBEL, RUMBLE and MON ACUMEN), aimed at creating models for managing the reduction of port noise from different points of view (technical, management, socio-economic) and at different levels (port sources, propagation). This will be possible by means of numerical simulations and by the definition of new algorithms and methodologies aimed to outline and define the best common strategies for the abatement of noise pollution. The result will be a set of easily replicable "instruments" effective for every port reality, that will allow to deal with the different aspects of port noise management in a holistic and therefore sustainable way, in order to guarantee a correct scientific approach and management when assessing the acoustical impact of ports
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