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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Assessment of the diffraction efficiency of novel barrier profiles using an MLS based approach

Watts, Gregory R., Morgan, P., Surgand, M. 29 May 2009 (has links)
No / In recent years there has been growing interest in the use of noise barrier profiles that can enhance the diffraction efficiency of plane barriers. These are placed on the top of the barrier in order to reduce sound diffracted into the shadow zone. A variety of shapes have been tested including T-shapes, multiple-edges and various cylindrical configurations. Despite numerous demonstrations that the profiles enhance performance there is no universal agreement on how the improvements can be quantified and incorporated into noise prediction models. Without such quantification it is likely that such profiles will not receive widespread acceptance. TRL has carried out an experimental investigation of the performance of novel-shaped barriers for the Transport Research Foundation. The approach relies on quantifying diffraction efficiency in the near field using a novel application of the Maximum Length Sequence (MLS)-based method. Measurements on 4 different profiles were taken in the vertical plane perpendicular to the barrier face. Two source and four receiver positions were used and results were obtained under a range of wind conditions. Results show large differences between the efficiency of the different options with the absorptive T-shaped and multiple-edge profiles performing best.

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