115 research outputs found
Design, theory, and measurement of a polarization insensitive absorber for terahertz imaging
We present the theory, design, and realization of a polarization-insensitive
metamaterial absorber for terahertz frequencies. We derive
geometrical-independent conditions for effective medium absorbers in general,
and for resonant metamaterials specically. Our fabricated design reaches and
absorptivity of 78% at 1.145 ThzComment: 6 Pages, 5 figures; figures update
Comment on "Quantum Friction - Fact or Fiction?"
If quantum friction existed [J.B. Pendry, New J. Phys. 12, 033028 (2010)] an
unlimited amount of useful energy could be extracted from the quantum vacuum
and Lifshitz theory would fail. Both are unlikely to be true.Comment: Comment on J.B. Pendry, New J. Phys. 12, 033028 (2010
Symmetry and reciprocity constraints on diffraction by gratings of quasi-planar particles
Symmetry and reciprocity constraints on polarization state of the field
diffracted by gratings of quasi-planar particles are considered. It is shown
that the optical activity effects observed recently in arrays of quasi-planar
plasmonic particles on a dielectric substrate are due to the reflection of the
field at the air-dielectric slab interface and are proportional to this
reflection coefficient.Comment: 11 pages, 3 figures, 12 references; minor corrections for better
appearanc
Perfect lensing with phase conjugating surfaces: Towards practical realization
It is theoretically known that a pair of phase conjugating surfaces can
function as a perfect lens, focusing propagating waves and enhancing evanescent
waves. However, the known experimental approaches based on thin sheets of
nonlinear materials cannot fully realize the required phase conjugation
boundary condition. In this paper we show that the ideal phase conjugating
surface is in principle physically realizable and investigate the necessary
properties of nonlinear and nonreciprocal particles which can be used to build
a perfect lens system. The physical principle of the lens operation is
discussed in detail and directions of possible experimental realizations are
outlined.Comment: 16 pages, 5 figure
Study (301)-(000) D2O band in 10200 - 10450 cm-1 spectral region
Measurements of D2O absorption spectra in the visible spectral region near 0.98 ΞΌm are performed using FT-spectrometer IFS-125M and Light-emitting diode (LED) as source of radiation. Water vapor spectrum has been obtained by averaging over 17136 scans recorded at 24 m optical path length, temperature 24 Π‘ and pressure of sample 27 mBar. Due to strong emission of LED source it was possible to achieve signal-to-noise ratio about 104 and to record weak lines with intensities of 6 10-27 cm/molecule. Comparisons with results of early works are made. Β© (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only
Repulsive Casimir Force in Chiral Metamaterials
We demonstrate theoretically that one can obtain repulsive Casimir forces and
stable nanolevitations by using chiral metamaterials. By extending the Lifshitz
theory to treat chiral metamaterials, we find that a repulsive force and a
minimum of the interaction energy exist for strong chirality, under realistic
frequency dependencies and correct limiting values (for zero and infinite
frequencies) of the permittivity, permeability, and chiral coefficients.Comment: 4 pages, 4 figures, letter. submitted to Phys. Rev. Let
On homogenization of electromagnetic crystals formed by uniaxial resonant scatterers
Dispersion properties of electromagnetic crystals formed by small uniaxial
resonant scatterers (magnetic or electric) are studied using the local field
approach. The goal of the study is to determine the conditions under which the
homogenization of such crystals can be made. Therefore the consideration is
limited by the frequency region where the wavelength in the host medium is
larger than the lattice periods. It is demonstrated that together with known
restriction for the homogenization related with the large values of the
material parameters there is an additional restriction related with their small
absolute values. From the other hand, the homogenization becomes allowed in
both cases of large and small material parameters for special directions of
propagation. Two unusual effects inherent to the crystals under consideration
are revealed: flat isofrequency contour which allows subwavelength imaging
using canalization regime and birefringence of extraordinary modes which can be
used for beam splitting.Comment: 16 pages, 12 figures, submitted to PR
ΠΠΏΡΠΈΠΌΠΈΠ·Π°ΡΠΈΡ ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΠΎΠ² Π»Π°Π·Π΅ΡΠ½ΠΎΠ³ΠΎ ΡΠ°ΡΠΊΠ°Π»ΡΠ²Π°Π½ΠΈΡ ΡΠΈΠ»ΠΈΠΊΠ°ΡΠ½ΡΡ ΡΡΠ΅ΠΊΠΎΠ» ΡΠ»Π»ΠΈΠΏΡΠΈΡΠ΅ΡΠΊΠΈΠΌΠΈ ΠΏΡΡΠΊΠ°ΠΌΠΈ Π² ΠΏΠ»ΠΎΡΠΊΠΎΡΡΠΈ, ΠΏΠ°ΡΠ°Π»Π»Π΅Π»ΡΠ½ΠΎΠΉ ΠΏΠΎΠ²Π΅ΡΡ Π½ΠΎΡΡΠΈ
Regression and neural network models of the process of laser splitting of silicate glasses by elliptical
beams in a plane parallel to the surface were obtained. To conduct a numerical experiment, a central compositional plan was used. The processing speed, laser beam power and its geometric parameters were selected as
variable factors. As responses, the values of maximum temperatures and the values of maximum thermoelastic
tensile stresses in the processing zone were determined, the calculation of which was performed using
the APDL programming language. An effective architecture for an artificial neural network created using
the TensorFlow program has been established. A comparative analysis of neural network and regression models was carried out. The influence of input parameters on responses was assessed. Using the MOGA algorithm
of the ANSYS program, the optimal modes for the formation of laser-induced cracks by elliptical beams were
determined, ensuring the effective implementation of parallel laser splitting of silicate glass.ΠΠΎΠ»ΡΡΠ΅Π½Ρ ΡΠ΅Π³ΡΠ΅ΡΡΠΈΠΎΠ½Π½ΡΠ΅ ΠΈ Π½Π΅ΠΉΡΠΎΡΠ΅ΡΠ΅Π²ΡΠ΅ ΠΌΠΎΠ΄Π΅Π»ΠΈ ΠΏΡΠΎΡΠ΅ΡΡΠ° Π»Π°Π·Π΅ΡΠ½ΠΎΠ³ΠΎ ΡΠ°ΡΠΊΠ°Π»ΡΠ²Π°Π½ΠΈΡ ΡΠΈΠ»ΠΈΠΊΠ°ΡΠ½ΡΡ
ΡΡΠ΅ΠΊΠΎΠ» ΡΠ»Π»ΠΈΠΏΡΠΈΡΠ΅ΡΠΊΠΈΠΌΠΈ ΠΏΡΡΠΊΠ°ΠΌΠΈ Π² ΠΏΠ»ΠΎΡΠΊΠΎΡΡΠΈ, ΠΏΠ°ΡΠ°Π»Π»Π΅Π»ΡΠ½ΠΎΠΉ ΠΏΠΎΠ²Π΅ΡΡ
Π½ΠΎΡΡΠΈ. ΠΠ»Ρ ΠΏΡΠΎΠ²Π΅Π΄Π΅Π½ΠΈΡ ΡΠΈΡΠ»Π΅Π½Π½ΠΎΠ³ΠΎ
ΡΠΊΡΠΏΠ΅ΡΠΈΠΌΠ΅Π½ΡΠ° Π±ΡΠ» ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ ΡΠ΅Π½ΡΡΠ°Π»ΡΠ½ΡΠΉ ΠΊΠΎΠΌΠΏΠΎΠ·ΠΈΡΠΈΠΎΠ½Π½ΡΠΉ ΠΏΠ»Π°Π½. Π ΠΊΠ°ΡΠ΅ΡΡΠ²Π΅ Π²Π°ΡΡΠΈΡΡΠ΅ΠΌΡΡ
ΡΠ°ΠΊΡΠΎΡΠΎΠ² Π²ΡΠ±ΡΠ°Π½Ρ ΡΠΊΠΎΡΠΎΡΡΡ ΠΎΠ±ΡΠ°Π±ΠΎΡΠΊΠΈ, ΠΌΠΎΡΠ½ΠΎΡΡΡ Π»Π°Π·Π΅ΡΠ½ΠΎΠ³ΠΎ ΠΏΡΡΠΊΠ° ΠΈ Π΅Π³ΠΎ Π³Π΅ΠΎΠΌΠ΅ΡΡΠΈΡΠ΅ΡΠΊΠΈΠ΅ ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΡ.
Π ΠΊΠ°ΡΠ΅ΡΡΠ²Π΅ ΠΎΡΠΊΠ»ΠΈΠΊΠΎΠ² ΠΎΠΏΡΠ΅Π΄Π΅Π»ΡΠ»ΠΈΡΡ Π·Π½Π°ΡΠ΅Π½ΠΈΡ ΠΌΠ°ΠΊΡΠΈΠΌΠ°Π»ΡΠ½ΡΡ
ΡΠ΅ΠΌΠΏΠ΅ΡΠ°ΡΡΡ ΠΈ Π·Π½Π°ΡΠ΅Π½ΠΈΡ ΠΌΠ°ΠΊΡΠΈΠΌΠ°Π»ΡΠ½ΡΡ
ΡΠ΅ΡΠΌΠΎΡΠΏΡΡΠ³ΠΈΡ
Π½Π°ΠΏΡΡΠΆΠ΅Π½ΠΈΠΉ ΡΠ°ΡΡΡΠΆΠ΅Π½ΠΈΡ Π² Π·ΠΎΠ½Π΅ ΠΎΠ±ΡΠ°Π±ΠΎΡΠΊΠΈ, ΡΠ°ΡΡΠ΅Ρ ΠΊΠΎΡΠΎΡΡΡ
Π±ΡΠ» Π²ΡΠΏΠΎΠ»Π½Π΅Π½ Ρ ΠΏΡΠΈΠΌΠ΅Π½Π΅Π½ΠΈΠ΅ΠΌ ΡΠ·ΡΠΊΠ° ΠΏΡΠΎΠ³ΡΠ°ΠΌΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΡ APDL. Π£ΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½Π° ΡΡΡΠ΅ΠΊΡΠΈΠ²Π½Π°Ρ Π°ΡΡ
ΠΈΡΠ΅ΠΊΡΡΡΠ° ΠΈΡΠΊΡΡΡΡΠ²Π΅Π½Π½ΠΎΠΉ Π½Π΅ΠΉΡΠΎΠ½Π½ΠΎΠΉ ΡΠ΅ΡΠΈ, ΡΠΎΠ·Π΄Π°Π½Π½ΠΎΠΉ Ρ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ΠΈΠ΅ΠΌ ΠΏΡΠΎΠ³ΡΠ°ΠΌΠΌΡ TensorFlow. ΠΡΠΎΠ²Π΅Π΄Π΅Π½ ΡΡΠ°Π²Π½ΠΈΡΠ΅Π»ΡΠ½ΡΠΉ Π°Π½Π°Π»ΠΈΠ· Π½Π΅ΠΉΡΠΎΡΠ΅ΡΠ΅Π²ΡΡ
ΠΈ ΡΠ΅Π³ΡΠ΅ΡΡΠΈΠΎΠ½Π½ΡΡ
ΠΌΠΎΠ΄Π΅Π»Π΅ΠΉ. ΠΡΠΏΠΎΠ»Π½Π΅Π½Π° ΠΎΡΠ΅Π½ΠΊΠ° Π²Π»ΠΈΡΠ½ΠΈΡ Π²Ρ
ΠΎΠ΄Π½ΡΡ
ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΠΎΠ² Π½Π° ΠΎΡΠΊΠ»ΠΈΠΊΠΈ. Π‘ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ΠΈΠ΅ΠΌ Π°Π»Π³ΠΎΡΠΈΡΠΌΠ° MOGA ΠΏΡΠΎΠ³ΡΠ°ΠΌΠΌΡ ANSYS ΠΎΠΏΡΠ΅Π΄Π΅Π»Π΅Π½Ρ ΠΎΠΏΡΠΈΠΌΠ°Π»ΡΠ½ΡΠ΅ ΡΠ΅ΠΆΠΈΠΌΡ
ΡΠΎΡΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΡ ΡΠ»Π»ΠΈΠΏΡΠΈΡΠ΅ΡΠΊΠΈΠΌΠΈ ΠΏΡΡΠΊΠ°ΠΌΠΈ Π»Π°Π·Π΅ΡΠ½ΠΎ-ΠΈΠ½Π΄ΡΡΠΈΡΠΎΠ²Π°Π½Π½ΡΡ
ΡΡΠ΅ΡΠΈΠ½, ΠΎΠ±Π΅ΡΠΏΠ΅ΡΠΈΠ²Π°ΡΡΠΈΠ΅ ΡΡΡΠ΅ΠΊΡΠΈΠ²Π½ΡΡ ΡΠ΅Π°Π»ΠΈΠ·Π°ΡΠΈΡ ΠΏΠ°ΡΠ°Π»Π»Π΅Π»ΡΠ½ΠΎΠ³ΠΎ Π»Π°Π·Π΅ΡΠ½ΠΎΠ³ΠΎ ΡΠ°ΡΠΊΠ°Π»ΡΠ²Π°Π½ΠΈΡ ΡΠΈΠ»ΠΈΠΊΠ°ΡΠ½ΠΎΠ³ΠΎ ΡΡΠ΅ΠΊΠ»Π°
Light-emitting-diode Fourier-transform spectroscopy of HD16O between 11200 and 12400 cm-1
The absorption spectrum of monodeuterated water, HDO has been investigated between 11200 and 12400 cm-1. The spectrum has been recorded using IFS-125M interferometer with spectral resolution of 0.05 cm-1. For measurements Whiteβs-type cell were used. The bright light emitting diode (LED) EDEI-1LS3-R was applied as a source of radiation. Signal to noise ratio was about 104. The spectral line parameters - line positions, intensities and half-widths were obtained by least square fitting. As a result of the spectrum analysis the line list containing more than 1500 lines was created. The spectral line parameters have been compared with the previous measured and calculated data. Β© (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only
Finding co-solvers on Twitter, with a little help from Linked Data
In this paper we propose a method for suggesting potential collaborators for solving innovation challenges online, based on their competence, similarity of interests and social proximity with the user. We rely on Linked Data to derive a measure of semantic relatedness that we use to enrich both user profiles and innovation problems with additional relevant topics, thereby improving the performance of co-solver recommendation. We evaluate this approach against state of the art methods for query enrichment based on the distribution of topics in user profiles, and demonstrate its usefulness in recommending collaborators that are both complementary in competence and compatible with the user. Our experiments are grounded using data from the social networking service Twitter.com
- β¦