A supersonic crowdion in mica: Ultradiscrete kinks with energy between 40^{40}K recoil and transmission sputtering

In this chapter we analyze in detail the behaviour and properties of the kinks found in an one dimensional model for the close packed rows of potassium ions in mica muscovite. The model includes realistic potentials obtained from the physics of the problem, ion bombardment experiments and molecular dynamics fitted to experiments. These kinks are supersonic and have an unique velocity and energy. They are ultradiscrete involving the translation of an interstitial ion, which is the reason they are called 'crowdions'. Their energy is below the most probable source of energy, the decay of the $^{40}$K isotope and above the energy needed to eject an atom from the mineral, a phenomenon that has been observed experimentallyComment: 28 pages, 15 figure

Experimental Investigation of the Performance of Two New Types of Soft-Switching Power Converters for Electric Ships

Power electronic converters are significant contributors to system mass, system loss, and system cost in the all-electric ship, and are, therefore, a significant area of interest. This paper investigates the reduction of switching losses in high power (MW level) converters. These losses remain a major obstacle to the development of converters capable of operating at higher frequencies and higher power densities using silicon power electronics. The Auxiliary Resonant Commutated Pole (ARCP) soft-switching converter topology offers the potential for minimization of switching losses, but has some inherent limitations. This paper examines two new converter designs based on the ARCP soft-switching topology that allow for more compact converter units by reducing the semiconductor switching losses generated within them. These concepts have been proven with simulation and laboratory testing of a sub-scale 20 kW test converter configurable in four distinct modes of operation. Efficiency has been measured for the two new ARCP topologies, as well as the original ARCP and standard hardswitching (conventional) technology using an induction motor as a load. New control algorithms to drive the ARCPs switches have also been developed, which improve the performance and reduce the amount of sensors that are required. The new proposed topologies are described and experimental waveforms and efficiency measurements are given.Center for Electromechanic