Søren Asbjørn Hattel

FORCE Technology · Hydro- and Aerodynamics

Based on data from a simple low-cost plug and play device for automatic logging of performance data we analyse the statistical properties of different performance indicators. Data originate from several ships from time periods of between one and twelve months of recorded data. We study correlations between the performance indicators and autologged...

Data collected by a simple low cost plug and play device for automatic logging is used to supplement data collected in noon reports for analysis of vessel performance. The quality of the performance analysis for the cases with and without the automatically logged data are compared. We observe that the scatter in the performance analysis is better t...

The dynamics of a system of three long Josephson transmission lines coupled at a common end point is investigated. We report several periodic fluxon states and trace out the corresponding zero field steps. The boundary conditions at the common point lead to a very different stability of steps for odd and even numbers of fluxons. In addition we find...

Monte Carlo simulations of the frustrated 2D XY model were carried out at small commensurate values of the frustration $f$. For $f=1/30$ a single transition was observed at which phase coherence (finite helicity modulus) and vortex lattice orientational order vanish together. For $f=1/56$ a new phase in which phase coherence is absent but orientati...

Collective depinning transitions in Coulomb solid-on-a-lattice systems are investigated in the low-charge-density limit. It is argued that depinning occurs at an inverted, continuous, dislocation unbinding transition of the Halperin-Nelson type. The depinning transition temperature is shown to be linear in the charge density, with a slope which is...

The equilibrium velocity of a 2pi-kink in a long Josephson junction is calculated analytically for low bias currents using the expression for the tunnel current from microscopic theory. The result is compared to the results of numerical simulations and excellent agreement is found, but the dynamics is very sensitive to the detailed form of the comp...

The statics and dynamics of a system of three long coupled Josephson junctions is described. Analytical soliton solutions are given and an oscillating mode for a soliton pinned at the common point of the junctions is given. The analytical results are accompanied by numerical simulations.

We present a numerical scheme for solving a nonlinear partial integro-differential equation with nonlocal time dependence. The equation describes the dynamics in a long Josephson junction modeled by use of the microscopic theory for tunneling between superconductors. We demonstrate that the detailed behavior of a solitonic mode (fluxon dynamics) in...

In this thesis we examine the principles of the approximate Werthamer model for the tunnel current in Josephson junctions originally developed by Odintsov et al. [12]. The major assumption of the model is that the current kernels in Werthamers expression for the tunnel current [6] can be approximated sufficiently well by a Dirichlet series with onl...

In the recent years the tunnel junctions of ultrasmall size have drawn attention of many researchers. This is due to new effects of correlated tunneling of charged particles (single electrons and Cooper pairs) in the junctions and their very alluring applications (see, e.g., Refs. 1-3). The physics of correlated transfer of single electrons in ultr...