The specific goal of this research is to develop a model of acoustic scattering due to volume heterogeneity consistent with existing propagation models in elastic layered sea beds and therefore to provide a self-consistent theoretical basis for improving and upgrading current bottom interaction codes (such as GABIM). At this first stage of research, the model should be capable of explaining bac...

Recent improvements in the parabolic equation method are combined to extend this approach to a larger class of seismo-acoustics problems. The variable rotated parabolic equation [J. Acoust. Soc. Am. 120, 3534-3538 (2006)] handles a sloping fluid-solid interface at the ocean bottom. The single-scattering solution [J. Acoust. Soc. Am. 121, 808-813 (2007)] handles range dependence within elastic s...

Inversion of Scholte wave is one of the most common methods to estimate the shear speeds in the bottom. This inversion involves running a forward model, with shear speeds in the sediment among the input parameters, and minimizing the data-model mismatch. A numerical model is developed based on the dynamic stiffness matrix approach to model the phase velocity dispersion of Scholte waves in this ...

My long term goal is to examine how inorganic factors, such as differences in sediment character or packing, contribute to the reflectance, scattering, and fluoresence of incident light at the seabed in coastal environments. Of particular interest is the degree to which the water column light field is sensitive to inorganic changes in bottom type, and whether such changes can be described in si...

This paper presents travel time geoacoustic inversion of broadband data collected on a vertical line array at short range of 230 m during the Shallow Water 2006 experiments. A ray-tracing method combined with a hybrid optimization algorithm that utilizes differential evolution and downhill simplex was used for the inversion of sediment properties. The ocean sound speed profile and geometric par...

Reported measurements of seabed scattering are largely confined to relatively low frequencies, up to 300 kHz, see, e.g., [Jackson and Richardson] and references therein. Still higher frequencies, up to a few megahertz, are used in seafloor imagery (e.g., in pencil-beam sonars), particularly to observe dynamic processes at the seafloor in shallow water. From the physics of sound-sediment interac...

The principal objective of this work is to contribute to the development of effective remote autonomous mine countermeasure operations by providing pertinent flow, heat flux and sediment transport characteristics in the benthic boundary layer to missions engaged in sea mine reconnaissance and hunting. These environmental characteristics govern acoustic and light propagation, chemical and biogen...

The collection, processing and certification of a new sediment Standard Reference Material (SRM), SRM 2704, is described. Collected from the bottom of the Buffalo River in New York State during the fall of 1986, SRM 2704 is certified for 25 elements with information provided on another 22 elements. Improvements in analytical methods as well as the application of well-defined quality-control pro...

As a part of the MAST2 GS-M Coastal Morphodynamics project, the predictions of four sediment transport models have been compared with detailed laboratory data sets obtained in the bottom boundary layer beneath regular waves, asymmetrical waves, and regular waves superimposed co-linearly on a current. Each data set was obtained in plane bed, sheet flow, conditions and each of the four untuned nu...