Method of making inflatable honeycomb Patent

Technique for making foldable, inflatable, plastic honeycomb core panels for use in building and bridge structures, light and radio wave reflectors, and spacecraf

Spoof surface plasmons guided by narrow grooves

An approximate description of surface waves propagating along periodically grooved surfaces is intuitively developed in the limit where the grooves are narrow relative to the period. Considering acoustic and electromagnetic waves guided by rigid and perfectly conducting gratings, respectively, the wave field is obtained by interrelating elementary approximations obtained in three overlapping spatial domains. Specifically, above the grating and on the scale of the period the grooves are effectively reduced to point resonators characterised by their dimensions as well as the geometry of their apertures. Along with this descriptive physical picture emerges an analytical dispersion relation, which agrees remarkably well with exact calculations and improves on preceding approximations. Scalings and explicit formulae are obtained by simplifying the theory in three distinguished propagation regimes, namely where the Bloch wavenumber is respectively smaller than, close to, or larger than that corresponding to a groove resonance. Of particular interest is the latter regime where the field within the grooves is resonantly enhanced and the field above the grating is maximally localised, attenuating on a length scale comparable with the period

Singular perturbations approach to localized surface-plasmon resonance: Nearly touching metal nanospheres

Metallic nano-structures characterised by multiple geometric length scales support low-frequency surface-plasmon modes, which enable strong light localization and field enhancement. We suggest studying such configurations using singular perturbation methods, and demonstrate the efficacy of this approach by considering, in the quasi-static limit, a pair of nearly touching metallic nano-spheres subjected to an incident electromagnetic wave polarized with the electric field along the line of sphere centers. Rather than attempting an exact analytical solution, we construct the pertinent (longitudinal) eigen-modes by matching relatively simple asymptotic expansions valid in overlapping spatial domains. We thereby arrive at an effective boundary eigenvalue problem in a half-space representing the metal region in the vicinity of the gap. Coupling with the gap field gives rise to a mixed-type boundary condition with varying coefficients, whereas coupling with the particle-scale field enters through an integral eigenvalue selection rule involving the electrostatic capacitance of the configuration. By solving the reduced problem we obtain accurate closed-form expressions for the resonance values of the metal dielectric function. Furthermore, together with an energy-like integral relation, the latter eigen-solutions yield also closed-form approximations for the induced-dipole moment and gap-field enhancement under resonance. We demonstrate agreement between the asymptotic formulas and a semi-numerical computation. The analysis, underpinned by asymptotic scaling arguments, elucidates how metal polarization together with geometrical confinement enables a strong plasmon-frequency redshift and amplified near-field at resonance.Comment: 13 pages, 7 figure

Inflatable honeycomb Patent

Inflatable honeycomb panel element for lightweight structures usable in space stations and other constructio

Manned space station Patent

Manned space station launched in packaged condition and self erecting in orbi

Dynamic duopoly with best-price clauses

This article investigates best-price clauses as a strategic devise to facilitate collusion in a dynamic duopoly game. Best-price clauses guarantee rebates on the purchase price if a customer finds a better price after his purchase. Two different price clauses are distinguished: "most favored customer" and "meet or release." I examine the collusive potential of both clauses in a finite-horizon duopoly model with homogeneous durable goods. In each period, new consumers enter the market. I show that in this context, meet-or-release clauses have a greater anticompetitive potential than most-favored-customer clauses