The autonomous underwater glider "Spray"

A small (50-kg, 2-m long) underwater vehicle with operating speeds of 20-30 cm/s and ranges up to 6000 km has been developed and field tested. The vehicle is essentially an autonomous profiling float that uses a buoyancy engine to cycle vertically and wings to glide horizontally while moving up and down. Operational control and data relay is provided by GPS navigation and two-way communication through ORBCOMM low-Earth-orbit satellites. Missions are envisioned with profile measurements repeated at a station or spaced along a transect. The initial instrument complement of temperature, conductivity, and pressure sensors was used to observe internal waves and tides in the Monterey underwater canyon     

Beach accretion and erosion, Burullus-Gamasa coast, Egypt

Several areas of erosion and accretion were observed along the Burullus-Gamasa beach. The accreted sands are coarser and less sorted than the eroded ones. Differentiation between them could be achieved on the basis of their grain-size fractions, shape of grain-size distribution curves and statistical grain-size parameter relationships.     

Plate boundaries and evolution of the Solomon Sea region

The Solomon Sea Plate was widely developed during late Oligocene, separating the proto-West Melanesian Arc from the proto-Trobriand Arc. Spreading in the Bismarck Sea and in the Woodlark Basin resulted from interaction between the Pacific and Australian Plates, specifically from the collision of the proto-West Melanesian Arc with north New Guinea, which occurred after arc reversal. This model explains the extensive Miocene, Pliocene, and Quaternary volcanism of the Papua New Guinea mainland as it related to southward subduction of the Trobriand Trough. Our interpreted plate motions are concordant with the geological evidence onshore and also with complex tectonic features in the Solomon Sea Basin Region.     

Influence of structural flexibility and wave interference on dynamic behavior of idealized offshore platform

An approximate method is presented to estimate the hydrodynamic loading and structural response of an idealized offshore platform subjected to a regular train of linear surface waves. The platform is taken to consist of four bottom-mounted, flexible, circular cylinders supporting a rigid deck and is assumed to be aligned parallel to the incident wave direction. The response of each column is assumed to be one-dimensional and to be governed by linear beam theory. The solution technique for the fluid velocity potential involves replacing scattered waves by equivalent plane waves together with non-planar, first-correction terms, and can be shown to be a large spacing approximation.Numerical results are presented which show the effect of hydrodynamic interference and structural flexibility on the platform response.     

Simplified method of deep-tow seismic profiling

To improve resolution of seismic-reflection profiles in continental slope water depths of 900 to 1500 m, a single hydrophone was towed about 150 m off the bottom to receive reflected signals from a surface-towed sparker sound source. That deep-towed hydrophone data show that valleys which appear V-shaped in records from a surface-towed hydrophone are flat-bottomed, and that subbottom reflections from an erosional unconformity can be much better resolved. The data produced by this technique are very hepful when used in conjunction with records from conventional surface-towed seismic-profiling equipment.     

Uptake of plutonium from seawater and sediment by a marine polychaete worm

The results of the uptake of plutonium 239 from sediment by a marine polychaete wormNereis diversicolor is reported in the present paper. A comparison is made of the relative importance of two possible uptake pathways, sediment and seawater by which this worm may obtain its plutonium body-burden. Under the laboratory conditions used for the comparison of those two routes it would appear thatNereis obtains greater than 98% of its body activity from seawater.