Localization of Electromagnetic Fields in Disordered Fano Metamaterials

We present the first study of disorder in planar metamaterials consisting of strongly interacting metamolecules, where coupled electric dipole and magnetic dipole modes give rise to a Fano-type resonant response and show that positional disorder leads to light localization inherently linked to collective magnetic dipole excitations. We demonstrate that the magnetic excitation persists in disordered arrays and results in the formation of "magnetic hot-spots"

Superlensing properties of one-dimensional dielectric photonic crystals

We present the experimental observation of the superlensing effect in a slab of a one-dimensional photonic crystal made of tilted dielectric elements. We show that this flat lens can achieve subwavelength resolution in different frequency bands. We also demonstrate that the introduction of a proper corrugation on the lens surface can dramatically improve both the transmission and the resolution of the imaged signal.Comment: 9 pages, 9 figure

On the first eigenvalue of the Dirichlet-to-Neumann operator on forms

We study a Dirichlet-to-Neumann eigenvalue problem for differential forms on a compact Riemannian manifold with smooth boundary. This problem is a natural generalization of the classical Steklov problem on functions. We derive a number of upper and lower bounds for the first eigenvalue in several contexts: many of these estimates will be sharp, and for some of them we characterize equality. We also relate these new eigenvalues with those of other operators, like the Hodge Laplacian or the biharmonic Steklov operator.Comment: 26 page

Weak localization of light in superdiffusive random systems

L\'evy flights constitute a broad class of random walks that occur in many fields of research, from animal foraging in biology, to economy to geophysics. The recent advent of L\'evy glasses allows to study L\'evy flights in controlled way using light waves. This raises several questions about the influence of superdiffusion on optical interference effects like weak and strong localization. Super diffusive structures have the extraordinary property that all points are connected via direct jumps, meaning that finite-size effects become an essential part of the physical problem. Here we report on the experimental observation of weak localization in L\'evy glasses and compare results with recently developed optical transport theory in the superdiffusive regime. Experimental results are in good agreement with theory and allow to unveil how light propagates inside a finite-size superdiffusive system

Uticaj gustine zasnivanja na prinos krme žutog zvezdana gajenog za kombinovano korišćenje

Birdsfoot trefoil grown for seed (cv. Bokor) was examined in agroecological conditions of Western Serbia during period 2007-2009. The goal was to determine herbage yield which could be achieved growing seed crop, using different interrow spacing (12.5, 25 and 50 cm) and various seeding rates (2, 4 and 8 kg ha-1). The highest hay yield was obtained in the third production year at the narrowest spacing and using the highest seeding rate (5.26 t ha-1). Total hay production during 3 years using birdsfoot trefoil seed crop for herbage yield ranged from 9.11 to 14.83 t ha-1 depending on row spacing and from 10.74 to 13.2 t ha-1 depending on seeding rate. The highest stand density (8 kg ha-1 seeding rate and 12.5 cm interrow spacing) produced the highest herbage yield of birdsfoot trefoil in the combined usage (for forage and seed production).Žuti zvezdan za proizvodnju semena, sorte Bokor, ispitivan je u agroekološkim uslovima zapadne Srbije, u periodu 2007-2009. godine. Ispitivana je količina biomase koja se može dobiti gajenjem žutog zvezdana za seme, pri zasnivanju na različitom međurednom rastojanju (12,5, 25 i 50 cm) i sa različitom normom semena (2, 4 i 8 kg ha-1). Najveći prinosi sena ostvareni su u trećoj godini gajenja useva na najužem međurednom rastojanju od 12,5 cm (6,56 t ha-1) i pri najvećoj količini semena od 8 kg ha-1 (5,73 t ha-1). Ukupna produkcija sena u trogodišnjem periodu korišćenja semenskog useva žutog zvezdana bila je od 9,11 do 14,83 ha-1 u zavisnosti od međurednog rastojanja i od 10,74 do 13,20 ha-1 u zavisnosti od setvene norme. Žuti zvezdan u kombinovanom korišćenju (za seme i krmu) je imao najveći potencijal za prinos krme pri većoj gustini zasnivanja (8 kg ha-1 i 12,5 cm međuredno rastojanje)

High orders of Weyl series for the heat content

This article concerns the Weyl series of spectral functions associated with the Dirichlet Laplacian in a $d$-dimensional domain with a smooth boundary. In the case of the heat kernel, Berry and Howls predicted the asymptotic form of the Weyl series characterized by a set of parameters. Here, we concentrate on another spectral function, the (normalized) heat content. We show on several exactly solvable examples that, for even $d$, the same asymptotic formula is valid with different values of the parameters. The considered domains are $d$-dimensional balls and two limiting cases of the elliptic domain with eccentricity $\epsilon$: A slightly deformed disk ($\epsilon\to 0$) and an extremely prolonged ellipse ($\epsilon\to 1$). These cases include 2D domains with circular symmetry and those with only one shortest periodic orbit for the classical billiard. We analyse also the heat content for the balls in odd dimensions $d$ for which the asymptotic form of the Weyl series changes significantly.Comment: 20 pages, 1 figur

The super-oscillating superlens

We demonstrate a lens that creates a sub-wavelength focal spot beyond the near-field by exploiting the phenomenon of super-oscillation

Co-sintering of dense electrophoretically deposited YSZ films on porous NiO-YSZ substrates for SOFC applications

An original process for the preparation of YSZ dense films with a thickness lower than 10 μm over NiO-YSZ substrates is presented. This process involves the preparation of a green membrane of NiO-YSZ and subsequent electrophoretic deposition (EPD) of commercial YSZ powder on this polymer-rich membrane. A single thermal treatment allowed removal of the organic compounds, sintering of the layers and full densification of the electrolyte. © 2005 Materials Research Society