941 research outputs found
Development of Small and Medium-Sized Regional Enterprises: Creation of Priority Areas (the Case of Sverdlovsk Region)
This article presents the results of the research which deals with the current level of development of small and medium enterprises (SMEs) in Sverdlovsk region. The study analyses the statistics of entrepreneurship development as well as Russian and international experience in this sphere. It also includes a sociological survey of entrepreneurs’ satisfaction with the business climate in the region. The research was aimed at elaborating guidelines for the long-term development of a regional entrepreneurship support system. This system seeks to facilitate the implementation of the ‘Strategy for the Development of Small and Medium Enterprises in Sverdlovsk Region before 2030’. As a result, an amalgam of strategic responses for the development of SMEs is presented. The completed response comprises measures intended to address the problems entrepreneurs face by developing SME support tools; to solve the endemic problems of the sector by improving the system of regional SME support; and to promote the realization of concrete priority areas for entrepreneurship development.The research work was carried out in collaboration with the Ural Federal University n.a. the First President of Russia B. N. Yeltsin and OOO “Analytical Centre Expert-Ural’” at the request of Sverdlovsk Regional Entrepreneurship Support Fund. The research was conducted in the period of September-November 2014. The state programme of Sverdlovsk region ‘Development of Industry and Science in Sverdlovsk Region Before 2020’ (approved by the Order of Sverdlovsk government of 24 October 2013 № 1293-ПП)
Transient Cherenkov radiation from an inhomogeneous string excited by an ultrashort laser pulse at superluminal velocity
An optical response of one-dimensional string made of dipoles with a
periodically varying density excited by a spot of light moving along the string
at the superluminal (sub-luminal) velocity is theoretically studied. The
Cherenkov radiation in such system is rather unusual, possessing both transient
and resonant character. We show that under certain conditions, in addition to
the resonant Cherenkov peak another Doppler-like frequency appears in the
radiation spectrum. Both linear (small-signal) and nonlinear regimes as well as
different string topologies are considered.Comment: accepted to Phys. Rev.
Double-cavity Fabry-Perot resonators based on one-dimensional silicon photonic crystals
This is the final version. Available from AIP Publishing via the DOI in this record.The 3rd Joint International Conference on Energy Engineering and Smart Materials (ICEESM-2018) and
International Conference on Nanotechnology and Nanomaterials in Energy (ICNNE-2018)In this work we report on optical properties of Fabry-Pérot (FP) resonator based on Si-air one-dimensional photonic crystal (1D PC) with coupled double-cavity modes (or defects). These defects obtained by infiltration of the air-cavities of refractive index (nAir) with the filler of tunable refractive index. In the periodic structure of 1D PC, the filling of two defined grooves with a filler with a refractive index different from nAirleads to the appearance of two resonant modes, the position of which can be adjusted purposefully with changing of n filler. In comparison with (λ / 2) air resonators, the splitting of the doublet increases, which is explained by the increase in the coupling between the resonant modes due to the decrease in reflection R of the internal mirror. The coupled FP resonators design is CMOS compatible and has potential for application in tuning of individual transmission bands in wave-division multiplexing systems as well as for multiple narrow filters in the wide infrared spectral range.We acknowledge financial support from: The Engineering and Physical Sciences Research Council (EPSRC) of the
United Kingdom via the EPSRC Grant No. EP/NO35569/1, and the Royal Society International Exchange Grant
2015/R3. The part of this research at the Ioffe Institute was supported by the Russian Federal Agency of Scientific
Organizations
Experiments on Sonoluminescence: Possible Nuclear and QED Aspects and Optical Applications
Experiments aimed at testing some hypothesis about the nature of Single
Bubble Sonoluminescence are discussed. A possibility to search for micro-traces
of thermonuclear neutrons is analyzed, with the aid of original low-background
neutron counter operating under conditions of the deep shielding from Cosmic
and other sources of background. Besides, some signatures of QED-contribution
to the light emission in SBSL are under the consideration, as well as new
approaches to probe a temperature inside the bubble. An applied-physics portion
of the program is presented also, in which an attention is being paid to
single- and a few-pulse light sources on the basis of SBSL.Comment: 4 pages; to be published by AIP in the Proc. ISNA-1
Sun-Sized Water Vapor Masers in Cepheus A
We present the first VLBI observations of a Galactic water maser (in Chepeus
A) made with a very long baseline interferometric array involving the
RadioAstron Earth-orbiting satellite station as one of its elements. We
detected two distinct components at -16.9 and 0.6 km/s with a fringe spacing of
66 microarcseconds. In total power, the 0.6 km/s component appears to be a
single Gaussian component of strength 580 Jy and width of 0.7 km/s.
Single-telescope monitoring showed that its lifetime was only 8~months. The
absence of a Zeeman pattern implies the longitudinal magnetic field component
is weaker than 120 mG. The space-Earth cross power spectrum shows two
unresolved components smaller than 15 microarcseconds, corresponding to a
linear scale of 1.6 x 10^11 cm, about the diameter of the Sun, for a distance
of 700 pc, separated by 0.54 km/s in velocity and by 160 +/-35 microarcseconds
in angle. This is the smallest angular structure ever observed in a Galactic
maser. The brightness temperatures are greater than 2 x 10^14K, and the line
widths are 0.5 km/s. Most of the flux (about 87%) is contained in a halo of
angular size of 400 +/- 150 microarcseconds. This structure is associated with
the compact HII region HW3diii. We have probably picked up the most prominent
peaks in the angular size range of our interferometer. We discuss three
dynamical models: (1) Keplerian motion around a central object, (2) two chance
overlapping clouds, and (3) vortices caused by flow around an obstacle (i.e.,
von Karman vortex street) with Strouhal number of about~0.3.Comment: 15 pages, 9 figures. Accepted for publication in ApJ, February 16,
201
Multi-channel Si-liquid crystal filter with fine tuning capability of individual channels for compensation of fabrication tolerances.
This is the final version. Available on open access from Springer via the DOI in this record.In this study, a technique for the optimization of the optical characteristics of multi-channel filters after fabrication is proposed. The multi-channel filter under consideration is based on a Si photonic crystal (PhC), tunable liquid crystal and opto-fluidic technologies. By filling air grooves in the one-dimensional, Si-Air PhC with a nematic liquid crystal, an efficiently coupled multi-channel filter can be realised in which a wide stop band is used for channel separation over a wide frequency range. By selectively tuning the refractive index in various coupled cavities, continuous individual tuning of the central channel (or edge channels) up to 25% of the total channel spacing is demonstrated. To our knowledge, this is the first report on the electro-optical solution for the compensation of fabrication tolerances in an integrated platform.This work has been supported by the ICGEE Programme (Ireland) and NAP-368 (Science Foundation Ireland)
Learning analytics in massive open online courses as a tool for predicting learner performance
Learning analytics in MOOCs can be used to predict learner performance, which is critical as higher education is moving towards adaptive learning. Interdisciplinary methods used in the article allow for interpreting empirical qualitative data on performance in specific types of course assignments to predict learner performance and improve the quality of MOOCs. Learning analytics results make it possible to take the most from the data regarding the ways learners engage with information and their level of skills at entry. The article presents the results of applying the proposed learning analytics algorithm to analyze learner performance in specific MOOCs developed by Ural Federal University and offered through the National Open Education Platform. © 2018, National Research University Higher School of Economics.This study was support- ed by financial assis- tance provided under the Resolution of the Government of the Rus sian Federation No. 211, Contract No. 02. A03.21.0006. Translated from Russian by I. Zhuchkova
Liquid Crystal WDM filter in Si photonic crystal technology with individual channel fine-tuning capability
We demonstrate a simple, low-cost solution for a single multi-channel WDM (Wavelength Division Multiplexing) filter with fine–tuning capability of individual channels. The filter is based on Si photonic crystal technology and can be integrated with CMOS processes. Although, fabrication technologies of Si integrated WDM systems have significantly advanced over the last decade, the most difficult challenges are posed by wavelength accuracy control as well as wavelength drifts and optical switching time. The proposed novel design of a multichannel integrated filter is based on the 1D silicon photonic crystal (PhC) model. By infiltration of the certain grooves of 1D PhC with matching filler, an efficient coupled Fabry-Pérot microresonator can be realized in which the wide-band stop band (SB) is used for frequency channel separation. By using the commercial nematic liquid crystal 5CB [1], we demonstrated electro-optical switching in the range of 30-50 nanoseconds and the continuous tuning of the individual channels up to 30 % of the channel-spacing. The fabricated multichannel filters have bandwidth of 0.1-0.9 nm with high extinction ration of 20dB at high modulation of reflection/ transmission coefficient. Using the gap map approach as a core engineering tool allows to predict formation and separation of transmission channels within the SBs and, thus, effectively determine the exact design parameters of the optical device. The obtained experimental spectral characteristics in the NIR range around 1.31 and 1.55 μm validated the proposed method and its applicability for the wavelength selective switching (WSS) as well as for the WDM in Si chip optical interconnects. [1] M. W. Geis, T. M. Lyszczarz, R. M. Osgood, and B. R. Kimball, " 30 to 50 ns liquid-crystal optical switches", Opt. Express 18, 18886-18893 (2010)The authors acknowledge the EPSRC Centre for Doctoral Training in
Metamaterials, Exeter, Devon for the continue support in this project
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