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