3,423 research outputs found
Photorealistic ray tracing of free-space invisibility cloaks made of uniaxial dielectrics
The design rules of transformation optics generally lead to spatially
inhomogeneous and anisotropic impedance-matched magneto-dielectric material
distributions for, e.g., free-space invisibility cloaks. Recently, simplified
anisotropic non-magnetic free-space cloaks made of a locally uniaxial
dielectric material (calcite) have been realized experimentally. In a
two-dimensional setting and for in-plane polarized light propagating in this
plane, the cloaking performance can still be perfect for light rays. However,
for general views in three dimensions, various imperfections are expected. In
this paper, we study two different purely dielectric uniaxial cylindrical
free-space cloaks. For one, the optic axis is along the radial direction, for
the other one it is along the azimuthal direction. The azimuthal uniaxial cloak
has not been suggested previously to the best of our knowledge. We visualize
the cloaking performance of both by calculating photorealistic images rendered
by ray tracing. Following and complementing our previous ray-tracing work, we
use an equation of motion directly derived from Fermats principle. The rendered
images generally exhibit significant imperfections. This includes the obvious
fact that cloaking does not work at all for horizontal or for ordinary linear
polarization of light. Moreover, more subtle effects occur such as
viewing-angle-dependent aberrations. However, we still find amazingly good
cloaking performance for the purely dielectric azimuthal uniaxial cloak.Comment: 12 pages, 3 figures, journal pape
Triggering and W-Polarisation Studies with CMS at the LHC
Results from studies on the commissioning of the Global Calorimeter Trigger (GCT)
of the CMS experiment are presented. Event-by-event comparisons of the hardware
with a bit-level software emulation are used to achieve 100% agreement for all trigger
quantities. In addition, a missing energy trigger based on jets is motivated using a
simulation study, and consequently implemented and commissioned in the GCT.
Furthermore, a templated-fit method for measuring the polarisation of W bosons
at the LHC in the “Helicity Frame” is developed, and validated in simulation. An
analysis of the first 3.2 pb−1 of
√
s = 7 TeV LHC data in the muon channel yields
values of (fL − fR)+ = 0.347 ± 0.070, f+
0 = 0.240 ± 0.176, and (fL − fR)− =
0.097 ± 0.088, f−
0 = 0.262 ± 0.196 for positive and negative charges respectively.
The errors quoted are statistical. A preliminary systematic study is also presented
Persistent issues in encryption software: A heuristic and cognitive walkthrough
The support information accompanying security software can be difficult to understand by end-users, who have little knowledge in cyber security. One mechanism for ensuring the integrity and confidentiality of information is encryption software. Unfortunately, software usability issues can hinder an end-user’s capability to properly utilise the security features effectively. To date there has been little research in investigating the usability of encryption software and proposing solutions for improving them. This research paper analysed the usability of encryption software targeting end-users. The research identified several issues that could impede the ability of a novice end-user to adequately utilise the encryption software. A set of proposed recommendations are suggested to improve encryption software which could be empirically verified through further research
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