Dynamic response of dolos armor units to drop test impact loads

Dolos concrete units have been used extensively throughout the world for the protection of shorelines and rubble structures. A three-dimensional finite element model is used to determine the states of dynamic stress in dolosse with varying dimensions and concrete properties. An analytical procedure is developed which accurately predicts the tensile stress in the shank and horizontal fluke of dolosse subject to drop test loading conditions Numerical examples are presented which illustrate the application of prediction and iso-stress equations.     

Validation of a finite difference method for the simulation of vortex-induced vibrations on a circular cylinder

The Karman Vortex Street generated by a circular cylinder is investigated by the numerical solution of the compressible Navier–Stokes equations in the incompressible Mach number range (Mach<0.3) using the Beam and Warming implicit scheme. The agreement with the fully incompressible projection method (Chorin, 1968) is fairly good while convergence time is very much better. The investigation suggests that the compressible Navier–Stokes equations may be used as an efficient alternative to study incompressible flows as well. Mach numbers just below 0.3 are enough to simulate incompressible flow behavior and at the same time do not cause numerical ill-conditioning in the solution. In addition, some relevant features of the vortices generated and carried by the wake of the cylinder could be fairly well captured.     

A field-based population model for the sediment toxicity test organism Leptocheirus plumulosus: I. Model development

We describe the development of a stage-structured population matrix model for the estuarine amphipod Leptocheirus plumulosus, a sediment toxicity test organism, based on regular sampling of a natural population for approximately 2 years. Annual population dynamics were characterized by abundance peaks in the spring and fall, and low densities in the summer and winter. We use a sequence of seasonal projection matrices to capture these qualitative patterns in population dynamics. We compare two methods for estimating transition probabilities: multiple regression and truncated singular value decomposition (SVD). Overall, SVD gave more realistic parameter estimates than regression, although fecundity estimation was problematic. There were predictable trends in growth, survival and fecundity within years. The SVD-derived model provides a framework for assessing the population-level effects of contaminants on Leptocheirus.     

Kimberlites: Their relation to mantle hotspots

Available age data support the hypothesis that kimberlite intrusions are formed by mantle hotspots. The hypothesis has been tested by inverting the volcanic traces formed by three hotspots to determine the post-Triassic motions of Africa, South America, and North America relative to these hotspots. Then, using these motions, the kimberlites intruded on these continents within the last 150 m.y. are relocated to their place of origin in the present hotspot reference frame. The result indicates that a majority of the kimberlites formed within 5° of a mantle hotspot. Statistical analysis shows that this kimberlite/hotspot correlation is significant at above the 90% level.     

Heterotrophic Nanoflagellates in the Pelagic Zone and Sediments of the Eastern Laptev Sea

Oceanology - For the first time, the species composition of heterotrophic nanoflagellates, their quantitative characteristics, and abundance and biomass of their main food objects—bacteria...     

Cosmic weather,physical-chemical systems,and the technosphere

This paper is a short review of publications on the influence that solar activity and geomagnetic disturbances (cosmic weather) have on physical-chemical systems. The effects of cosmic weather may some-times be detected by the presence of an uncontrolled factor in these experiments. Direct reactions to cosmic weather are reliably identified in quantitative observations over various test systems, mainly water solutions. The effects of cosmic weather are also found from the data obtained by monitoring some simple physical systems, including semiconductors. All these effects are either cosmic physical rhythms or they are easily registered sporadic heliogeophysical events (e.g., magnetic storms). There are convincing data that demonstrate the influence that cosmic weather has on the accident rate in various engineering and physical systems. Researchers are at odds on the physical nature of the main physical agent, but the contribution of electromagnetic fields to these processes is considered important.