A new genus of Barleeidae Gray, 1857 (Mollusca, Gastropoda) and the first occurrence of the genus Pseudodiala Ponder, 1967 off the Brazilian coast

Ketosia new genus, Barleeidae, is described from off the Brazilian coast, based on conchological analysis of specimens collected through the REVIZEE Program and others from oil prospecting, off the coast of Rio de Janeiro State (24 o W). The new genus is characterised by: anteriorly convex to slightly convex shell profile; protoconch paucispiral, dome-shaped, its surface covered with irregular pits; and teleoconch smooth but with minute deep pits. The aperture is oval, and may be separated from the peripheral region of the teleoconch by a depression. Two new species belonging to this new genus are described herein. We also record, for the first time, the occurrence of the genus Pseudodiala Ponder, 1967 from the Brazilian coast, describing a new species.

Design of a Frangible Laminated Composite Launch Tube Closure

The concepts of designing a laminated composite frangible launch tube closure are elaborated. The frangible closure is a convex shell structure of which the external failure pressure is much higher than the internal failure pressure. The frangible closure is designed in such a way that when subjected to an internal impulsive pressure of magnitude greater than certain value, the closure will be broken into several pieces in accordance with a predetermined failure pattern. A number of frangible closures of different sizes are fabricated and subjected to burst strength tests. The failure modes and the effects of some specific design variables on the burst strength of the closure are studied using the experimental results. Basically, the frangible closure can achieve the design objectives.

On the Minimal Convex Shell of a Convex Body

For any convex body C in ℝd we introduce the notion of the convex shell and we prove that there exists a unique "minimal" convex shell, extending the notion of the minimal spherical shell of C. Then we prove that a "typical" convex body touches the boundary of its minimal convex shell in precisely d + 2 points.