Amethod for approximating acoustic-field-amplitude uncertaintycaused by environmental uncertainties

摘要

In underwater acoustics, the accuracy of computational field predictions is commonly limited byuncertainty in environmental parameters. An approximate technique for determining the probabilitydensity function (PDF) of computed field amplitude, A, from known environmental uncertainties ispresented here. The technique can be applied to several, N, uncertain parameters simultaneously,requires N+ 1 field calculations, and can be used with any acoustic field model. The techniqueimplicitly assumes independent input parameters and is based on finding the optimum spatial shiftbetween field calculations completed at two different values of each uncertain parameter. This shiftinformation is used to convert uncertain-environmental-parameter distributions into PDF(A). Thetechnique's accuracy is good when the shifted fields match well. Its accuracy is evaluated inrange-independent underwater sound channels via an L_1 error-norm defined between approximateand numerically converged results for PDF(A). In 50-m- and 100-m-deep sound channels with 0.5%uncertainty in depth (N=1) at frequencies between 100 and 800 Hz, and for ranges from 1 to 8 km,95% of the approximate field-amplitude distributions generated L_1 values less than 0.52 using onlytwo field calculations. Obtaining comparable accuracy from traditional methods requires of order 10field calculations and up to 10~NwhenN>1.