234 research outputs found
Applicability of point dipoles approximation to all-dielectric metamaterials
All-dielectric metamaterials consisting of high-dielectric inclusions in a
low-dielectric matrix are considered as a low-loss alternative to resonant
metal-based metamaterials. In this contribution we investigate the
applicability of the point electric and magnetic dipoles approximation to
dielectric meta-atoms on the example of a dielectric ring metamaterial. Despite
the large electrical size of high-dielectric meta-atoms, the dipole
approximation allows for accurate prediction of the metamaterials properties
for the rings with diameters up to ~0.8 of the lattice constant. The results
provide important guidelines for design and optimization of all-dielectric
metamaterials.Comment: 10 pages, 5 fugures, submitted to Physical Review
All-dielectric one-dimensional periodic structures for total omnidirectional reflection and partial spontaneous emission control
A remarkable property of one-dimensional all-dielectric periodic structures
has recently been reported, namely a one-dimensional lattice can totally
reflect electromagnetic wave of any polarization at all angles within a
prescribed frequency region. Unlike their metallic counterpart, such
all-dielectric omnidirectional mirrors are nearly free of loss at optical
frequencies. Here we discuss the physics, design criteria and applications of
the thin-film all-dielectric omnidirectional mirror. The experimental
demonstration of the mirror is presented at optical frequencies.Comment: 6 pages, 9 figures; submitted to IEEE Journal of Lightwave Technolog
Observation of total omnidirectional reflection from a one-dimensional dielectric lattice
We show that under certain conditions one-dimensional dielectric lattice
possesses total omnidirectional reflection of incident light. The predictions
are verified experimentally using Na3AlF6/ZnSe multilayer structure developed
by means of standard optical technology. The structure was found to exhibit
reflection coefficient more then 99% in the range of incident angles 0-86
(degree) at the wavelength of 632.8 nm for s-polarization. The results are
believed to stimulate new experiments on photonic crystals and controlled
spontaneous emission.Comment: 4 pages, 5 figures; submitted to Applied Physics
Homogenization of metasurfaces formed by random resonant particles in periodical lattices
In this paper we suggest a simple analytical method for description of
electromagnetic properties of a geometrically regular two-dimensional
subwavelength arrays (metasurfaces) formed by particles with randomly
fluctuating polarizabilities. Such metasurfaces are of topical importance due
to development of mass-scale bottom-up fabrication methods, for which
fluctuations of the particles sizes, shapes, and/or composition are inevitable.
Understanding and prediction of electromagnetic properties of such random
metasurfaces is a challenge. We propose an analytical homogenization method
applicable for normal wave incidence on particles arrays with dominating
electric dipole responses and validate it with numerical point-dipole modeling
using the supercell approach. We demonstrate that fluctuations of particles
polarizabilities lead to increased diffuse scattering despite the subwavelength
lattice constant of the array. The proposed method can be readily extended to
oblique incidence and particles with both electric and magnetic dipole
resonances.Comment: 10 pages, 5 figure
Bloch-mode analysis for retrieving effective parameters of metamaterials
We introduce a new approach for retrieving effective parameters of
metamaterials based on the Bloch-mode analysis of quasi-periodic composite
structures. We demonstrate that, in the case of single-mode propagation, a
complex effective refractive index can be assigned to the structure, being
restored by our method with a high accuracy. We employ both surface and volume
averaging of the electromagnetic fields of the dominating (fundamental) Bloch
modes to determine the Bloch and wave impedances, respectively. We discuss how
this method works for several characteristic examples, and demonstrate that
this approach can be useful for retrieval of both material and wave effective
parameters of a broad range of metamaterials.Comment: 12 pages, 10 figure
Development of methodology for assessing the innovation potential of organisations in the region
Nowadays, one of the main aims of any organization is to increase innovation component of growth. It is also necessary to move to intensive development, what is always connected with introduction of new industrial technologies and output of rival products, because it is not enough only to increase industrial scale to reach competitive advantages in the market. But, in fact, there is a problem, connected with the lack of complex researches, methodical developments and conceptual approaches to assessment the innovation potential and its effective use. So the research of innovation capacity is a topical problem for all modern organizations
Development of methodology for assessing the innovation potential of organisations in the region
Nowadays, one of the main aims of any organization is to increase innovation component of growth. It is also necessary to move to intensive development, what is always connected with introduction of new industrial technologies and output of rival products, because it is not enough only to increase industrial scale to reach competitive advantages in the market. But, in fact, there is a problem, connected with the lack of complex researches, methodical developments and conceptual approaches to assessment the innovation potential and its effective use. So the research of innovation capacity is a topical problem for all modern organizations
Euclidean-signature Supergravities, Dualities and Instantons
We study the Euclidean-signature supergravities that arise by compactifying
D=11 supergravity or type IIB supergravity on a torus that includes the time
direction. We show that the usual T-duality relation between type IIA and type
IIB supergravities compactified on a spatial circle no longer holds if the
reduction is performed on the time direction. Thus there are two inequivalent
Euclidean-signature nine-dimensional maximal supergravities. They become
equivalent upon further spatial compactification to D=8. We also show that
duality symmetries of Euclidean-signature supergravities allow the harmonic
functions of any single-charge or multi-charge instanton to be rescaled and
shifted by constant factors. Combined with the usual diagonal dimensional
reduction and oxidation procedures, this allows us to use the duality
symmetries to map any single-charge or multi-charge p-brane soliton, or any
intersection, into its near-horizon regime. Similar transformations can also be
made on non-extremal p-branes. We also study the structures of duality
multiplets of instanton and (D-3)-brane solutions.Comment: Latex, 50 pages, typos corrected and references adde
Improving Methods for the Assessment of the Innovative Potential of the Organization on the Example of OJSC «Berezovsky Cheese-Making Plant»
The essence of the innovative capacity has been determined. The proposed method of the integrated assessment of the innovation is based on two modules: scientific-technical and industrial-financial, which includes a number of indicators that characterize the innovative condition of the organization. Also, the innovative capacity has been analyzed on the example of OJSC "Berezovsky Cheese-making Plant" in accordance with this method
Improving Methods for the Assessment of the Innovative Potential of the Organization on the Example of OJSC «Berezovsky Cheese-Making Plant»
The essence of the innovative capacity has been determined. The proposed method of the integrated assessment of the innovation is based on two modules: scientific-technical and industrial-financial, which includes a number of indicators that characterize the innovative condition of the organization. Also, the innovative capacity has been analyzed on the example of OJSC "Berezovsky Cheese-making Plant" in accordance with this method
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