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REPORT DATE (DD-MM-YYYY)
March 2003
REPORT TYPE
DISTRIBUTION/AVAILABILITY STATEMENTApproved for public release; distribution unlimited.
SUPPLEMENTARY NOTESAMSCode:622784H7111 DA Project: AH71
ABSTRACTParabolic equation (PE) techniques have been successfully used to obtain numerical solutions of sound pressure attenuation in which sound propagation is affected by turbulence and vertical gradients in wind and temperature. The PE models generally produce accurate attenuation values, but the execution time is excessive for applications when near real-time results are required. To obtain sound level attenuation predictions at selected locations more quickly, we are developing an artificial neural network. As a first step in tliis effort, tlie PE and boundary conditions were modified to obtain a nondimensional version, written in the MATLAB code. Tliis nondimensional version was developed to be used to train the artificial neural network because a fewer number of parameters (seven) would be required to be specified, resulting in a reduced number of model runs to develop the training algorithm. Tliis report documents the derivation of tlie appropriate equations that are used in tlie modified (nondimensional) version of tlie acoustic propagation model. In addition, graphical data are provided tliat identify the sensitivity of sound pressure attenuation to each of tlie seven nondimensional parameters.
SUBJECT TERMS