Transmission Loss Calculations HLS Research（传输损耗计算HLS研究）.ppt

Advanced Acoustical Modeling Tools for ESME Martin Siderius and Michael Porter Science Applications Int. Corp. 10260 Campus Point Dr., San Diego, CA sideriust@ michael.b.porter@ Acoustic Modeling Goals Through modeling, try to duplicate sounds heard by marine mammals (e.g. SONAR, shipping) Develop both high fidelity and very efficient simulation tools Acoustic Modeling Goals Accurate field predictions in 3 dimensions Computational efficiency (i.e. fast run times) Propagation ranges up to 200 km R-D bathymetry/SSP/seabed with depths 0-5000 m Frequency band 0-10 kHz (or higher) Moving receiver platform Arbitrary waveforms (broadband time-series) Directional sources Model Comparisons Motivation Fast Coupled NM Method Range dependent environment is treated as series of range independent sectors Each sector has a set of normal modes Modes are projected between sectors allowing for transfer of energy between modes (matrix multiply) Algorithm marches through sectors Speeds up in flat bathymetry areas Pre-calculation of modes allows for gains in run-time (important for 3D calculation) Very fast at lower frequencies and shallow water Mid Atlantic Bight: Example Mammal Risk Mitigation Map Shipping Simulator Using the fast coupled normal-mode routine shipping noise can be simulated This approach can rapidly produce snapshots of acoustic data (quasi-static approximation) Self noise can also be simulated (i.e. on a towed array) Together with a wind noise model this can predict the background ambient noise level Example: Simulated BTR Input environment, array geometry (e.g. towed array hydrophone positions) and specify ship tracks (SL, ranges, bearings, time) Example: BTR from SWELLEX96 Computing Time-Series Data for Moving Receiver 1. Interpolating the Impulse Response In most cases the broad band impulse response cannot be simply interpolated For example, take responses from 2 points at slightly different ranges: 2. “Stitching” the Responses Together Even if the impulse