Wave loading on axisymmetric bodies using axisymmetric hybrid integral equation method

The wave diffraction problem on axisymmetric structures are solved by treating the fluid field as two separate domains. The velocity potential in the inner domain is represented by a 1/r type Green's function whilst that of the outer domain is represented by an eigenfunction expansion. The simple form of the Green's function in the inner domain reduces significantly the computational effort whilst the eigenfunction expansion in the outer domain is able to satisfy the radiation boundary condition completely. The method requires to have elements cover the entire containing boundary. Results for a number of typical structural geometries are presented and discussions are made on the effect of various parameters.     

Rapid visualization of plankton abundance and taxonomic composition using the Video Plankton Recorder

Traditional methods for determining spatial distributions of planktonic taxa involve net, pump, and bottle collections followed by the tedious and time-consuming task of plankton sample analysis. Thus, plankton ecologists often require months or even years to process samples from a single study. In this paper, we present a method that allows rapid visualization of the distribution of planktonic taxa while at sea. Rapid characterization of plankton distributions is essential in the dynamic physical environment, where biological and physical patterns can change quickly. Such a “sample-and-observe” capability is necessary for mapping ephemeral features (such as patches, eddies, jets, plumes) and determining appropriate locations to conduct more localized sampling, including in situ observational studies. We describe the techniques used in imaging the plankton, analyzing the video, and visualizing the data. We present an example of at-sea data analysis conducted aboard R.V. Columbus Iselin on Georges Bank in May 1994 and visualizations of the 3-dimensional distribution of selected planktonic taxa in a 2 × 2 km × 90 m volume of seawater. A video of the image processing and visualization is included on the CD-ROM accompanying this volume and is an essential part of this paper.     

Petrology and mineral chemistry of sedimentary rocks from the Western Solomon Sea

Multichannel seismic reflection profiles recorded in the northern Red Sea show structures that we interpret to be a result of the intrusion of uppermost Miocene salt. We believe that the evaporites are underlaid by attenuated continental crust and the flow of salt is due to renewed faulting of basement in the Pliocene when sea floor spreading began between latitudes 21°N and 15°30°N.     

Recent and Late Holocene environments on the southeastern shelf of the Laptev Sea as inferred from microfossil data

The study of diatoms and benthic foraminifers from the southeastern shelf of the Laptev Sea shows that their most diverse and abundant recent assemblages populate the peripheral underwater part of the Lena River delta representing the marginal filter of the sea. This area is characterized by an intense interaction between the fresh waters of the Siberian rivers and the basin seawater, the Atlantic one included. Local Late Holocene (～last 2300 years) environments reflect the main regional and global paleoclimatic changes, the Medieval Warm Period (～600–1100 years B.P.) and the Little Ice Age (～100–600 years B.P.) inclusive. In addition, the composition and distribution of planktonic foraminifers implies a strong influence of the Atlantic water during the Holocene optimum ～5100–6200 years B.P.