Hydrodinamic Aspects of a High-Speed SWATH and New Hull Form

The main problems of high-speed ships operating in open seas are their insufficient seaworthiness and speed loss in high sea states. Small Water-plane Area Twin-Hulls (SWATH) are characterised by excellent seaworthiness, but the hull forms of a traditional SWATH are not suited for higher speeds. A new shape of underwater gondola has been developed for a semi-planing (S/P) SWATH. Additionally, hydrofoils can be applied to this ship to provide the optimal dynamic draught and trim, to mitigate motions in rough seas, and even to carry a part of the ship weight. The relative speed of this SWATH can be beneficially increased up to the displacement Froude number 3. Several concept designs addressing naval and civil transportation needs are outlined in this paper

Quasi 1D Metal-Semiconductor Heterostructures

The band offsets occurring at the abrupt heterointerfaces of suitable material combinations offer a powerful design tool for high performance or even new kinds of devices. Because of a large variety of applications for metal-semiconductor heterostructures and the promise of low-dimensional systems to present exceptional device characteristics, nanowire heterostructures gained particular interest over the past decade. However, compared to those achieved by mature two-dimensional processing techniques, quasi one-dimensional (1D) heterostructures often suffer from low interface and crystalline quality. For the GaAs-Au system, we demonstrate exemplarily a new approach to generate epitaxial and single crystalline metal-semiconductor nanowire heterostructures with atomically sharp interfaces using standard semiconductor processing techniques. Spatially resolved Raman measurements exclude any significant strain at the lattice mismatched metal-semiconductor heterojunction. On the basis of experimental results and simulation work, a novel self-assembled mechanism is demonstrated which yields one-step reconfiguration of a semiconductor-metal core-shell nanowire to a quasi 1D axially stacked heterostructure via flash lamp annealing. Transmission electron microscopy imaging and electrical characterization confirm the high interface quality resulting in the lowest Schottky barrier for the GaAs-Au system reported to date. Without limiting the generality, this novel approach will open up new opportunities in the syntheses of other metal-semiconductor nanowire heterostructures and thus facilitate the research of high-quality interfaces in metal-semiconductor nanocontacts