28 research outputs found
Towards a Process Algebra for Shared Processors
AbstractWe present initial work on a timed process algebra that models sharing of processor resources allowing preemption at arbitrary points in time. This enables us to model both the functional and the timely behaviour of concurrent processes executed on a single processor. We give a refinement relation that describes that one process is more deterministic than another. Applications of the model for process scheduling, programming language semantics, and kernel development are outlined
Securing Statically-verified Communications Protocols Against Timing Attacks
AbstractWe present a federated analysis of communication protocols which considers both security properties and timing. These are not entirely independent observations of a protocol; by using timing observations of an executing protocol it is possible to calculate encryption keys which were intended to be secret or to deduce derived information about the nature of the communication even in the presence of unbreakable encryption. Our analysis is based on expressing the protocol as a high-level model and deriving from this process calculus models analysable by the Imperial PEPA Compiler and the LySatool
Pinhole junctions in d-wave superconductors
We present a self consistent treatment of pinhole junctions in
superconductors. The current-phase relation is studied at different
temperatures and at different angles between the crystal -axis
and the junction (surface) normal. We show that the critical current of a
junction can be reduced by pair-breaking effects at the separation. We also
study the Josephson energy of a pinhole as a function of the phase difference
across the junction. In particular are mapped the positions of the energy
minima at different temperatures as functions of
(), the crystal orientations of the left and right
superconductors. With decreasing temperature there is an increasing range of
crystal orientations where varies continuously from 0 to .Comment: 14 pages, RevTeX, 11 PostScript figures, accepted for publication in
Physica
Shot noise in normal metal-d-wave superconducting junctions
We present theoretical calculations and predictions for the shot noise in
voltage biased junctions of superconductors and normal metal
counter-electrodes. In the clean limit for the d-wave superconductor the shot
noise vanishes at zero voltage because of resonant Andreev reflection by
zero-energy surface bound states. We examine the sensitivity of this resonance
to impurity scattering. We report theoretical results for the magnetic field
dependence of the shot noise, as well the fingerprints of subdominant - and
pairing channels.Comment: 15 pages, 8 figures and 3 tables embedde