1,781 research outputs found
Diophantine approximation on Veech surfaces
We show that Y. Cheung's general -continued fractions can be adapted to
give approximation by saddle connection vectors for any compact translation
surface. That is, we show the finiteness of his Minkowski constant for any
compact translation surface. Furthermore, we show that for a Veech surface in
standard form, each component of any saddle connection vector dominates its
conjugates. The saddle connection continued fractions then allow one to
recognize certain transcendental directions by their developments
Spectral stability of the Coulomb-Dirac Hamiltonian with anomalous magnetic moment
We show that the point spectrum of the standard Coulomb-Dirac operator H_0 is
the limit of the point spectrum of the Dirac operator with anomalous magnetic
moment H_a as the anomaly parameter tends to 0. For negative angular momentum
quantum number kappa, this holds for all Coulomb coupling constants c for which
H_0 has a distinguished self-adjoint realisation. For positive kappa, however,
there are some exceptional values for c, and in general an index shift between
the eigenvalues of H_0 and the limits of eigenvalues of H_a appears,
accompanied with additional oscillations of the eigenfunctions of H_a very
close to the origin
Construction and Test of New Precision Drift-Tube Chambers for the ATLAS Muon Spectrometer
ATLAS muon detector upgrades aim for increased acceptance for muon triggering
and precision tracking and for improved rate capability of the muon chambers in
the high-background regions of the detector with increasing LHC luminosity. The
small-diameter Muon Drift Tube (sMDT) chambers have been developed for these
purposes. With half of the drift-tube diameter of the MDT chambers and
otherwise unchanged operating parameters, sMDT chambers share the advantages of
the MDTs, but have an order of magnitude higher rate capability and can be
installed in detector regions where MDT chambers do not fit in. The chamber
assembly methods have been optimized for mass production, minimizing
construction time and personnel. Sense wire positioning accuracies of 5 ?micons
have been achieved in serial production for large-size chambers comprising
several hundred drift tubes. The construction of new sMDT chambers for
installation in the 2016/17 winter shutdown of the LHC and the design of sMDT
chambers in combination with new RPC trigger chambers for replacement of the
inner layer of the barrel muon spectrometer are in progress
Ergodicity for Infinite Periodic Translation Surfaces
For a Z-cover of a translation surface, which is a lattice surface, and which
admits infinite strips, we prove that almost every direction for the
straightline flow is ergodic
Recurrence in generic staircases
The straight-line flow on almost every staircase and on almost every square
tiled staircase is recurrent. For almost every square tiled staircase the set
of periodic orbits is dense in the phase space
A Functional Reference Model for Manufacturing Execution Systems in the Automotive Industry
Being confronted with IT strategic questions of how to constantlyreduce IT operating costs and at the same time live up to everincreasing manufacturing demands, automobile manufacturers areencountering problems to find appropriate IT support forproduction planning and execution. Moreover, they are facing thechallenge to clearly define and demarcate Enterprise ResourcePlanning (ERP) and Manufacturing Execution Systems (MES)functionality. Despite the existence of a number of standardizationefforts addressing MES functionality, automobile manufacturersare still struggling to reach a common understanding for the termMES and a clear functional design. The paper addresses this needby developing a functional reference model for MES in theautomotive industry based on a multiple case study approach. Thecase studies examine the design and implementation ofmanufacturing-related functionality in four leading automotivemanufacturing companies
Affine diffeomorphisms of translation surfaces : periodic points, fuchsian groups, and arithmeticity
Probing fractal magnetic domains on multiple length scales in Nd2Fe14B
Using small-angle neutron scattering, we demonstrate that the complex
magnetic domain patterns at the surface of Nd2Fe14B, revealed by quantitative
Kerr and Faraday microscopy, propagate into the bulk and exhibit structural
features with dimensions down to 6 nm, the domain wall thickness. The observed
fractal nature of the domain structures provides an explanation for the
anomalous increase in the bulk magnetization of Nd2Fe14B below the
spin-reorientation transition. These measurements open up a rich playground for
studies of fractal structures in highly anisotropic magnetic systems.Comment: Accepted for publication in Phys. Rev. Lett. (4 pages, 4 figures
- …