Journal of Food, Agriculture and Environment

An optimization process for a T-shaped noise barrier coated by primitive root diffuser equipped with perforated sheets

Author(s):

Mohammad Reza Monazzam ¹, Mahdiyeh Naderzadeh ^2*, Samaneh Momen Bellah Fard ³

Recieved Date: 2011-11-18, Accepted Date: 2012-01-03

Abstract:

Application of noise barriers along highways and motorways as a drastic noise control solution is already known in most countries. The aim of this paper was to optimize the efficiency of a T-shaped roadside noise barrier covered with primitive root diffuser (PRD) using a new cost function based on the new multiple-impedance discontinuities method. The parameter to optimize is the position of perforated sheets inside the wells of PRD barrier. Moving the perforated sheet’s position changes the amount of imaginary part of admittance. With the use of this fact and its effect on overall performance of diffuser barrier, it is possible to find an optimum sequences for perforated sheet locations within the wells to achieve a high performance for its corresponding PRD barrier. This study was conducted through an iteration method considering dominant frequency of 125 Hz as an example in traffic noise frequency characteristics in Tehran, Iran. It was found that the best depth sequence of perforated sheets was at 0.01, 0.01, 0.26, 0.03, 0.2 and 0.03 cm from the end of each well in a primitive root diffuser with design frequency of 400 Hz. The highest improvement was seen by adding perforated sheets in the proper optimize places inside the diffuser’s wells by a further 4 dB (A). It is also found that maximum effectiveness of the optimized barrier compared with a T-shaped barrier equipped with PR diffuser is observed when the receivers were 4-6 m above the ground and 50-100 m away from the barrier

Keywords:

Optimization, new multiple-impedance discontinuities, perforated sheets, primitive root diffuser, noise barrier, boundary element method, traffic noise, diffusive surface, noise control, insertion loss

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Journal: Journal of Food, Agriculture and Environment
Year: 2012
Volume: 10
Issue: 1
Category: Environment
Pages: 993-996

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