The approach includes both theoretical and measurement components. One measurement approach exploits the very high geoacoustic information content in direct path measurements of seabed reflection and scattering. Another measurement approach, based on long-range reverberation, has much less information content but is nonetheless a powerful way to explore scales inherent in the seabed. Both kinds...

The ocean floor is home to a wealth of species, some of which—such as this bamboo coral (Isidella tentaculum)—have only recently been discovered. Proponents of seabed mining claim it causes less ecological damage than terrestrial extraction. But some researchers are concerned that seabed mining could overwhelm deep-sea ecosystems, adding to concerns about the health of the oceans.

UWB (ultra wide-band) pulse radar is a promising candidate for surveillance systems. The fast SEABED (Shape Estimation Algorithm based on BST and Extraction of Directly scattered waves) imaging algorithm is deployed in the application of UWB pulse radar in fields that require real-time operations. However, since the SEABED algorithm uses signals received at multiple locations, this method eithe...

A technique has been developed to measure the speed of sound in marine sediments at discrete frequencies from 0.6 to 10 kHz by transmitting pulses from acoustic projectors within the water column and measuring the angle to which they are refracted on directional receivers buried in the seabed. The receivers are vectors sensors that measure three-axis acceleration and pressure allowing acoustic ...

The seabed can be classified using data from vertical, split-beam echosounders. This was demonstrated recently using amodel parameterized with acoustic estimates of slope, roughness, normal-incidence backscattering strength, and variation of backscattering strength by frequency and incidence angle. These seabed classifications were interpreted and validated using published surficial geology map...

The kurtosis statistic is introduced as a sensitive tool for efficient preliminary analysis of flowinduced vibration response data. The kurtosis of sequential blocks of time series data allows one to distinguish single mode lock-in events. The problem of predicting lock-in is then discussed. Instructional examples are introduced to illustrate the relative importance of flow-speed, power-in leng...

This paper presents results obtained as part of the DeepStar Phase 10 program on VIV Factors of Safety. The objective was to develop a general methodology to calibrate Factors of Safety for VIV-induced fatigue and to apply it to partially straked risers. This was achieved using reliability methods, accepted industry VIV prediction software and state-of-the-art model test experiments. Most oil c...

Vortex-induced vibration (VIV) of a long riser in sheared current is often considered as an energy balance problem: Excitation forces in the power-in region add an equal amount of energy to the system as is dissipated by damping forces outside this region and structural damping. A riser may have different excitation and damping regions depending on the actual oscillation frequency, cross-sectio...