Signal processing by opto-optical interactions between self-localized and free propagating beams in liquid crystals

The reorientational nonlinearity of nematic liquid crystals enables a self-localized spatial soliton and its waveguide to be deflected or destroyed by a control beam propagating across the cell. We demonstrate a simple all-optical readdressing scheme by exploiting the lens-like perturbation induced by an external beam on both a nematicon and a co-polarized guided signal of different wavelength. Angular steering as large as 2.2 degrees was obtained for control powers as low as 32mW in the near infrared

Deforming Maps for Lie Group Covariant Creation and Annihilation Operators

Any deformation of a Weyl or Clifford algebra A can be realized through a `deforming map', i.e. a formal change of generators in A. This is true in particular if A is covariant under a Lie algebra g and its deformation is induced by some triangular deformation $U_h g$ of the Hopf algebra $Ug$. We propose a systematic method to construct all the corresponding deforming maps, together with the corresponding realizations of the action of $U_h g$. The method is then generalized and explicitly applied to the case that $U_h g$ is the quantum group $U_h sl(2)$. A preliminary study of the status of deforming maps at the representation level shows in particular that `deformed' Fock representations induced by a compact $U_h g$ can be interpreted as standard `undeformed' Fock representations describing particles with ordinary Bose or Fermi statistics.Comment: Latex file, 26 pages, no figures. Extended changes. Final Version to appear in J. Math. Phy

Twin Grid-array as 3.6 GHz Epidermal Antenna for Potential Backscattering 5G Communication

Emerging 5G infrastructures can boost innovative paradigms for future wearable and epidermal devices exploiting low-power (even passive) wireless backscattering-based communication. To compensate high body- and path-losses, and to extend the read range, array configurations are required. This work proposes a flexible monolithic epidermal layout, based on Krauss array concept, that operates at 3.6 GHz and it is suitable to be directly attached to the human body. The antenna involves a dual grid configuration with a main radiating grid backed by a grid reflector placed in touch with the skin. Overall, the amount of conductor an dielectric substrate are minimized with benefit to breathability. The antenna is suitable to surface feeding and produces a broadside radiation. Parametric analysis are performed and an optimal configuration of four-cells grid is derived and experimentally demonstrated to provide a maximum gain of more than 6 dBi

A dynamic model of ballasted rail track with bituminous sub-ballast layer

The bituminous sub-ballast layer within the ballasted rail track allows some mechanical and environmental advantages. An analytical model of a ballasted rail track with sub-ballast layer has been proposed by considering the rail as viscous-elastic continuous beam discretely supported, at four levels of elasticity. The model was used to compare the mechanical performance of both ballasted track with and without bituminous sub-ballast layer. The results confirmed that the bituminous sub-ballast layer reduces the dynamic forces on the ground and achieves the technical objectives as reduction of ground borne vibrations and increase of the design life of the rail track