161 research outputs found
Effect of grain refinement on deformation behavior of technical grade titanium under tension
The paper deals with the study on the impact of grain refinement by severe plastic deformation upon the microstructure, as well as deformation and fracture behavior under tensile loading of technical grade titanium. The microstructure of coarse- and ultra-fine grain technical grade titanium was investigated by optical, transmission electron microscopy and X-ray diffraction. In situ monitoring of deformation behavior was conducted by means of acoustic emission and digital image correlation. Scanning electron microscopy was employed for fracture surface observation. The results of the tensile tests have revealed significant growth in ultimate strength and decrease of ductility due to grain-boundary strengthening. The experimental data obtained allow one to get the appropriate understanding of the mechanisms responsible for variation of mechanical properties and fracture patterns as well as to attain quantitative estimation of strain localization induced by the grain refinement
Correlation effects during liquid infiltration into hydrophobic nanoporous mediums
Correlation effects arising during liquid infiltration into hydrophobic
porous medium are considered. On the basis of these effects a mechanism of
energy absorption at filling porous medium by nonwetting liquid is suggested.
In accordance with this mechanism, the absorption of mechanical energy is a
result expenditure of energy for the formation of menisci in the pores on the
shell of the infinite cluster and expenditure of energy for the formation of
liquid-porous medium interface in the pores belonging to the infinite cluster
of filled pores. It was found that in dependences on the porosity and,
consequently, in dependences on the number of filled pores neighbors, the
thermal effect of filling can be either positive or negative and the cycle of
infiltration-defiltration can be closed with full outflow of liquid. It can
occur under certain relation between percolation properties of porous medium
and the energy characteristics of the liquid-porous medium interface and the
liquid-gas interface. It is shown that a consecutive account of these
correlation effects and percolation properties of the pores space during
infiltration allow to describe all experimental data under discussion
The Phantom Bounce: A New Oscillating Cosmology
An oscillating universe cycles through a series of expansions and
contractions. We propose a model in which ``phantom'' energy with
grows rapidly and dominates the late-time expanding phase. The universe's
energy density is so large that the effects of quantum gravity are important at
both the beginning and the end of each expansion (or contraction). The bounce
can be caused by high energy modifications to the Friedmann equation, which
make the cosmology nonsingular. The classic black hole overproduction of
oscillating universes is resolved due to their destruction by the phantom
energy.Comment: Four pages, one figure. V3: version to appear in JCA
Gravitational Wave Bursts from Collisions of Primordial Black Holes in Clusters
The rate of gravitational wave bursts from the mergers of massive primordial
black holes in clusters is calculated. Such clusters of black holes can be
formed through phase transitions in the early Universe. The central black holes
in clusters can serve as the seeds of supermassive black holes in galactic
nuclei. The expected burst detection rate by the LISA gravitational wave
detector is estimated.Comment: 10 pages, 2 figure
Gamma Ray Bursts from the Evolved Galactic Nuclei
A new cosmological scenario for the origin of gamma ray bursts (GRBs) is
proposed. In our scenario, a highly evolved central core in the dense galactic
nucleus is formed containing a subsystem of compact stellar remnants (CSRs),
such as neutron stars and black holes. Those subsystems result from the
dynamical evolution of dense central stellar clusters in the galactic nuclei
through merging of stars, thereby forming (as has been realized by many
authors) the short-living massive stars and then CSRs. We estimate the rate of
random CSR collisions in the evolved galactic nuclei by taking into account,
similar to Quinlan & Shapiro (1987), the dissipative encounters of CSRs, mainly
due to radiative losses of gravitational waves, which results in the formation
of intermediate short-living binaries, with further coalescence of the
companions to produce GRBs. We also consider how the possible presence of a
central supermassive black hole, formed in a highly evolved galactic nucleus,
influences the CSR binary formation. This scenario does not postulate ad hoc a
required number of tight binary neutron stars in the galaxies. Instead, it
gives, for the most realistic parameters of the evolved nuclei, the expected
rate of GRBs consistent with the observed one, thereby explaining the GRB
appearance in a natural way of the dynamical evolution of galactic nuclei. In
addition, this scenario provides an opportunity for a cosmological GRB
recurrence, previously considered to be a distinctive feature of GRBs of a
local origin only. We also discuss some other observational tests of the
proposed scenario.Comment: 25 pages, LATEX, uses aasms4.sty, accepted by Ap
The Development of Youth Entrepreneurship at a University Taking into the Factor of Cooperation with Partners
The article presents the authorβs view on the development of youth entrepreneurship at a university based on the factor of cooperation with partners. The main objective of the study is to establish the methodological framework for the use of the potential of the partners of a university for the development of youth entrepreneurship. The relevance of the study is determined by the need to develop approaches to stimulate the development of youth entrepreneurship in Russia, including at universities. The article considers theoretical and methodological foundations of youth entrepreneurship. The authors defines the stimulatory and constraining factors, as well as endogenous (transformational and transactional) and exogenous conditions for the development of youth entrepreneurship. A comprehensive mechanism is proposed in the context of four main structural units and principles of entrepreneurship taking into account the interaction of the university with its partners - businesses, territorial, educational and scientific communities. The authors systematizes the specific experience of Russian universities in the framework of the functioning elements of an integrated mechanism for the development of youth entrepreneurship, considering interaction with their partners. Common features and differences in the intensity of the support and development of youth entrepreneurship have been identified. The significant role of partners at this stage of the functioning of universities is obvious. Interaction with partners of a university in the development of youth entrepreneurship has a significant potential, based on the relevance of entrepreneurship support as a whole, the need to intensify the development of business activities of individual companies and institutions through the implementation of entrepreneurial initiatives and the social importance of discovering entrepreneurial skills in young people. The universities that have been studied use opportunities to attract external projects that further the development of youth entrepreneurship. The results can be used for analysis of current activity and formation of strategic documents in the field of youth entrepreneurship development for universities, private companies, scientific organizations and public associations.Π ΡΡΠ°ΡΡΠ΅ ΠΏΡΠ΅Π΄ΡΡΠ°Π²Π»Π΅Π½ Π°Π²ΡΠΎΡΡΠΊΠΈΠΉ Π²Π·Π³Π»ΡΠ΄ Π½Π° ΡΠ°Π·Π²ΠΈΡΠΈΠ΅ ΠΌΠΎΠ»ΠΎΠ΄Π΅ΠΆΠ½ΠΎΠ³ΠΎ ΠΏΡΠ΅Π΄ΠΏΡΠΈΠ½ΠΈΠΌΠ°ΡΠ΅Π»ΡΡΡΠ²Π° Π² ΡΠ½ΠΈΠ²Π΅ΡΡΠΈΡΠ΅ΡΠ΅ Π½Π° ΠΎΡΠ½ΠΎΠ²Π΅ ΡΠ°ΠΊΡΠΎΡΠ° Π²Π·Π°ΠΈΠΌΠΎΠ΄Π΅ΠΉΡΡΠ²ΠΈΡ Ρ ΠΏΠ°ΡΡΠ½Π΅ΡΠ°ΠΌΠΈ. ΠΡΠ½ΠΎΠ²Π½Π°Ρ ΡΠ΅Π»Ρ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ ΡΠΎΡΡΠΎΠΈΡ Π² ΡΠΎΡΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΠΈ ΠΌΠ΅ΡΠΎΠ΄ΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΎΠΉ Π±Π°Π·Ρ Π΄Π»Ρ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ΠΈΡ ΠΏΠΎΡΠ΅Π½ΡΠΈΠ°Π»Π° ΠΏΠ°ΡΡΠ½Π΅ΡΠΎΠ² ΡΠ½ΠΈΠ²Π΅ΡΡΠΈΡΠ΅ΡΠ° Π΄Π»Ρ ΡΠ°Π·Π²ΠΈΡΠΈΡ ΠΌΠΎΠ»ΠΎΠ΄Π΅ΠΆΠ½ΠΎΠ³ΠΎ ΠΏΡΠ΅Π΄ΠΏΡΠΈΠ½ΠΈΠΌΠ°ΡΠ΅Π»ΡΡΡΠ²Π°. ΠΠΊΡΡΠ°Π»ΡΠ½ΠΎΡΡΡ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ ΠΎΠΏΡΠ΅Π΄Π΅Π»ΡΠ΅ΡΡΡ Π½Π΅ΠΎΠ±Ρ
ΠΎΠ΄ΠΈΠΌΠΎΡΡΡΡ Π²ΡΡΠ°Π±ΠΎΡΠΊΠΈ ΠΏΠΎΠ΄Ρ
ΠΎΠ΄ΠΎΠ² ΠΊ ΡΡΠΈΠΌΡΠ»ΠΈΡΠΎΠ²Π°Π½ΠΈΡ ΡΠ°Π·Π²ΠΈΡΠΈΡ ΠΌΠΎΠ»ΠΎΠ΄Π΅ΠΆΠ½ΠΎΠ³ΠΎ ΠΏΡΠ΅Π΄ΠΏΡΠΈΠ½ΠΈΠΌΠ°ΡΠ΅Π»ΡΡΡΠ²Π° Π² Π ΠΎΡΡΠΈΠΈ, Π² ΡΠΎΠΌ ΡΠΈΡΠ»Π΅ Π½Π° Π±Π°Π·Π΅ ΡΠ½ΠΈΠ²Π΅ΡΡΠΈΡΠ΅ΡΠΎΠ². Π ΡΡΠ°ΡΡΠ΅ ΡΠ°ΡΡΠΌΠΎΡΡΠ΅Π½Ρ ΡΠ΅ΠΎΡΠ΅ΡΠΈΠΊΠΎ-ΠΌΠ΅ΡΠΎΠ΄ΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΠ΅ ΠΎΡΠ½ΠΎΠ²Ρ ΠΌΠΎΠ»ΠΎΠ΄Π΅ΠΆΠ½ΠΎΠ³ΠΎ ΠΏΡΠ΅Π΄ΠΏΡΠΈΠ½ΠΈΠΌΠ°ΡΠ΅Π»ΡΡΡΠ²Π°. ΠΠ²ΡΠΎΡΠ°ΠΌΠΈ ΠΎΠΏΡΠ΅Π΄Π΅Π»Π΅Π½Ρ ΡΡΠΈΠΌΡΠ»ΠΈΡΡΡΡΠΈΠ΅ ΠΈ ΡΠ΄Π΅ΡΠΆΠΈΠ²Π°ΡΡΠΈΠ΅ ΡΠ°ΠΊΡΠΎΡΡ, Π° ΡΠ°ΠΊΠΆΠ΅ ΡΠ½Π΄ΠΎΠ³Π΅Π½Π½ΡΠ΅ (ΡΡΠ°Π½ΡΡΠΎΡΠΌΠ°ΡΠΈΠΎΠ½Π½ΡΠ΅ ΠΈ ΡΡΠ°Π½ΡΠ°ΠΊΡΠΈΠΎΠ½Π½ΡΠ΅) ΠΈ ΡΠΊΠ·ΠΎΠ³Π΅Π½Π½ΡΠ΅ ΡΡΠ»ΠΎΠ²ΠΈΡ ΡΠ°Π·Π²ΠΈΡΠΈΡ ΠΌΠΎΠ»ΠΎΠ΄Π΅ΠΆΠ½ΠΎΠ³ΠΎ ΠΏΡΠ΅Π΄ΠΏΡΠΈΠ½ΠΈΠΌΠ°ΡΠ΅Π»ΡΡΡΠ²Π°. ΠΡΠ΅Π΄Π»ΠΎΠΆΠ΅Π½ ΠΊΠΎΠΌΠΏΠ»Π΅ΠΊΡΠ½ΡΠΉ ΠΌΠ΅Ρ
Π°Π½ΠΈΠ·ΠΌ Π² ΡΠ°Π·ΡΠ΅Π·Π΅ ΡΠ΅ΡΡΡΠ΅Ρ
ΠΎΡΠ½ΠΎΠ²Π½ΡΡ
ΡΡΡΡΠΊΡΡΡΠ½ΡΡ
Π±Π»ΠΎΠΊΠΎΠ² ΠΈ ΠΏΡΠΈΠ½ΡΠΈΠΏΡ ΡΠ°Π·Π²ΠΈΡΠΈΡ ΠΏΡΠ΅Π΄ΠΏΡΠΈΠ½ΠΈΠΌΠ°ΡΠ΅Π»ΡΡΡΠ²Π° Ρ ΡΡΠ΅ΡΠΎΠΌ Π²Π·Π°ΠΈΠΌΠΎΠ΄Π΅ΠΉΡΡΠ²ΠΈΡ ΡΠ½ΠΈΠ²Π΅ΡΡΠΈΡΠ΅ΡΠ° ΡΠΎ ΡΠ²ΠΎΠΈΠΌΠΈ ΠΏΠ°ΡΡΠ½Π΅ΡΠ°ΠΌΠΈ β Π΄Π΅Π»ΠΎΠ²ΡΠΌ, ΡΠ΅ΡΡΠΈΡΠΎΡΠΈΠ°Π»ΡΠ½ΡΠΌ, ΠΎΠ±ΡΠ°Π·ΠΎΠ²Π°ΡΠ΅Π»ΡΠ½ΡΠΌ ΠΈ Π½Π°ΡΡΠ½ΡΠΌ ΡΠΎΠΎΠ±ΡΠ΅ΡΡΠ²Π°ΠΌΠΈ. ΠΠ²ΡΠΎΡΠ°ΠΌΠΈ ΡΡΠ°ΡΡΠΈ ΡΠΈΡΡΠ΅ΠΌΠ°ΡΠΈΠ·ΠΈΡΠΎΠ²Π°Π½ ΡΠ°ΡΡΠ½ΡΠΉ ΠΎΠΏΡΡ ΡΠΎΡΡΠΈΠΉΡΠΊΠΈΡ
ΡΠ½ΠΈΠ²Π΅ΡΡΠΈΡΠ΅ΡΠΎΠ² Π² ΡΠ°ΠΌΠΊΠ°Ρ
ΡΡΠ½ΠΊΡΠΈΠΎΠ½ΠΈΡΠΎΠ²Π°Π½ΠΈΡ ΡΠ»Π΅ΠΌΠ΅Π½ΡΠΎΠ² ΠΊΠΎΠΌΠΏΠ»Π΅ΠΊΡΠ½ΠΎΠ³ΠΎ ΠΌΠ΅Ρ
Π°Π½ΠΈΠ·ΠΌΠ° ΡΠ°Π·Π²ΠΈΡΠΈΡ ΠΌΠΎΠ»ΠΎΠ΄Π΅ΠΆΠ½ΠΎΠ³ΠΎ ΠΏΡΠ΅Π΄ΠΏΡΠΈΠ½ΠΈΠΌΠ°ΡΠ΅Π»ΡΡΡΠ²Π° Ρ ΡΡΠ΅ΡΠΎΠΌ Π²Π·Π°ΠΈΠΌΠΎΠ΄Π΅ΠΉΡΡΠ²ΠΈΡ Ρ ΠΏΠ°ΡΡΠ½Π΅ΡΠ°ΠΌΠΈ ΡΠ½ΠΈΠ²Π΅ΡΡΠΈΡΠ΅ΡΠ°. ΠΡΡΠ²Π»Π΅Π½Ρ ΠΎΠ±ΡΠΈΠ΅ ΡΠ΅ΡΡΡ ΠΈ ΡΠ°Π·Π»ΠΈΡΠΈΠ΅ Π² ΠΈΠ½ΡΠ΅Π½ΡΠΈΠ²Π½ΠΎΡΡΠΈ ΠΏΠΎΠ΄Π΄Π΅ΡΠΆΠΊΠΈ ΠΈ ΡΠ°Π·Π²ΠΈΡΠΈΡ ΠΌΠΎΠ»ΠΎΠ΄Π΅ΠΆΠ½ΠΎΠ³ΠΎ ΠΏΡΠ΅Π΄ΠΏΡΠΈΠ½ΠΈΠΌΠ°ΡΠ΅Π»ΡΡΡΠ²Π°. ΠΡΠΈ ΡΡΠΎΠΌ Π΄Π΅ΠΉΡΡΠ²Π΅Π½Π½Π°Ρ ΡΠΎΠ»Ρ ΠΏΠ°ΡΡΠ½Π΅ΡΠΎΠ² Π½Π° ΡΠ΅ΠΊΡΡΠ΅ΠΌ ΡΡΠ°ΠΏΠ΅ ΡΡΠ½ΠΊΡΠΈΠΎΠ½ΠΈΡΠΎΠ²Π°Π½ΠΈΡ ΡΠ½ΠΈΠ²Π΅ΡΡΠΈΡΠ΅ΡΠΎΠ² ΠΎΡΠ΅Π²ΠΈΠ΄Π½Π°. ΠΠ·Π°ΠΈΠΌΠΎΠ΄Π΅ΠΉΡΡΠ²ΠΈΠ΅ Ρ ΠΏΠ°ΡΡΠ½Π΅ΡΠ°ΠΌΠΈ ΡΠ½ΠΈΠ²Π΅ΡΡΠΈΡΠ΅ΡΠ° Π² ΠΎΠ±Π»Π°ΡΡΠΈ ΡΠ°Π·Π²ΠΈΡΠΈΡ ΠΌΠΎΠ»ΠΎΠ΄Π΅ΠΆΠ½ΠΎΠ³ΠΎ ΠΏΡΠ΅Π΄ΠΏΡΠΈΠ½ΠΈΠΌΠ°ΡΠ΅Π»ΡΡΡΠ²Π° ΠΈΠΌΠ΅Π΅Ρ Π·Π½Π°ΡΠΈΡΠ΅Π»ΡΠ½ΡΠΉ ΠΏΠΎΡΠ΅Π½ΡΠΈΠ°Π», ΠΎΠΏΠΈΡΠ°ΡΡΠΈΠΉΡΡ Π½Π° Π°ΠΊΡΡΠ°Π»ΡΠ½ΠΎΡΡΡ ΠΏΠΎΠ΄Π΄Π΅ΡΠΆΠΊΠΈ ΠΏΡΠ΅Π΄ΠΏΡΠΈΠ½ΠΈΠΌΠ°ΡΠ΅Π»ΡΡΡΠ²Π° Π² ΡΠ΅Π»ΠΎΠΌ, Π½Π΅ΠΎΠ±Ρ
ΠΎΠ΄ΠΈΠΌΠΎΡΡΠΈ ΠΈΠ½ΡΠ΅Π½ΡΠΈΡΠΈΠΊΠ°ΡΠΈΠΈ ΡΠ°Π·Π²ΠΈΡΠΈΡ Ρ
ΠΎΠ·ΡΠΉΡΡΠ²ΡΡΡΠ΅ΠΉ Π΄Π΅ΡΡΠ΅Π»ΡΠ½ΠΎΡΡΠΈ ΠΎΡΠ΄Π΅Π»ΡΠ½ΡΡ
ΠΊΠΎΠΌΠΏΠ°Π½ΠΈΠΉ ΠΈ ΡΡΡΠ΅ΠΆΠ΄Π΅Π½ΠΈΠΉ Π·Π° ΡΡΠ΅Ρ ΡΠ΅Π°Π»ΠΈΠ·Π°ΡΠΈΠΈ ΠΏΡΠ΅Π΄ΠΏΡΠΈΠ½ΠΈΠΌΠ°ΡΠ΅Π»ΡΡΠΊΠΈΡ
ΠΈΠ½ΠΈΡΠΈΠ°ΡΠΈΠ² ΠΈ ΠΎΠ±ΡΠ΅ΡΡΠ²Π΅Π½Π½ΠΎΠΉ Π·Π½Π°ΡΠΈΠΌΠΎΡΡΠΈ ΡΠ°ΡΠΊΡΡΡΠΈΡ ΠΏΡΠ΅Π΄ΠΏΡΠΈΠ½ΠΈΠΌΠ°ΡΠ΅Π»ΡΡΠΊΠΈΡ
ΡΠΏΠΎΡΠΎΠ±Π½ΠΎΡΡΠ΅ΠΉ ΠΌΠΎΠ»ΠΎΠ΄Π΅ΠΆΠΈ. ΠΡΠ΅ ΠΏΡΠΎΠ°Π½Π°Π»ΠΈΠ·ΠΈΡΠΎΠ²Π°Π½Π½ΡΠ΅ Π°Π²ΡΠΎΡΠ°ΠΌΠΈ ΡΠ°Π±ΠΎΡΡ ΡΠ½ΠΈΠ²Π΅ΡΡΠΈΡΠ΅ΡΡ ΠΈΡΠΏΠΎΠ»ΡΠ·ΡΡΡ Π²ΠΎΠ·ΠΌΠΎΠΆΠ½ΠΎΡΡΠΈ, ΡΠΏΠΎΡΠΎΠ±ΡΡΠ²ΡΡΡΠΈΠ΅ ΡΠ°Π·Π²ΠΈΡΠΈΡ ΠΌΠΎΠ»ΠΎΠ΄Π΅ΠΆΠ½ΠΎΠ³ΠΎ ΠΏΡΠ΅Π΄ΠΏΡΠΈΠ½ΠΈΠΌΠ°ΡΠ΅Π»ΡΡΡΠ²Π°. Π Π΅Π·ΡΠ»ΡΡΠ°ΡΡ ΡΠ°Π±ΠΎΡΡ ΠΌΠΎΠ³ΡΡ Π±ΡΡΡ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½Ρ Π΄Π»Ρ Π°Π½Π°Π»ΠΈΠ·Π° ΡΠ΅ΠΊΡΡΠ΅ΠΉ Π΄Π΅ΡΡΠ΅Π»ΡΠ½ΠΎΡΡΠΈ, Π° ΡΠ°ΠΊΠΆΠ΅ ΡΠΎΡΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΡ ΡΡΡΠ°ΡΠ΅Π³ΠΈΡΠ΅ΡΠΊΠΈΡ
Π΄ΠΎΠΊΡΠΌΠ΅Π½ΡΠΎΠ² Π² ΡΡΠ΅ΡΠ΅ ΡΠ°Π·Π²ΠΈΡΠΈΡ ΠΌΠΎΠ»ΠΎΠ΄Π΅ΠΆΠ½ΠΎΠ³ΠΎ ΠΏΡΠ΅Π΄ΠΏΡΠΈΠ½ΠΈΠΌΠ°ΡΠ΅Π»ΡΡΡΠ²Π° Π΄Π»Ρ ΡΠ½ΠΈΠ²Π΅ΡΡΠΈΡΠ΅ΡΠΎΠ², ΡΠ°ΡΡΠ½ΡΡ
ΠΊΠΎΠΌΠΏΠ°Π½ΠΈΠΉ, Π½Π°ΡΡΠ½ΡΡ
ΠΎΡΠ³Π°Π½ΠΈΠ·Π°ΡΠΈΠΈ ΠΈ ΠΎΠ±ΡΠ΅ΡΡΠ²Π΅Π½Π½ΡΡ
ΠΎΠ±ΡΠ΅Π΄ΠΈΠ½Π΅Π½ΠΈΠΉ.Π‘ΡΠ°ΡΡΡ Π²ΡΠΏΠΎΠ»Π½Π΅Π½Π° Π² ΡΠΎΠΎΡΠ²Π΅ΡΡΡΠ²ΠΈΠΈ Ρ ΠΏΠ»Π°Π½ΠΎΠΌ ΠΠΠ ΠΠ½ΡΡΠΈΡΡΡΠ° ΡΠΊΠΎΠ½ΠΎΠΌΠΈΠΊΠΈ Π£ΡΠ Π ΠΠ β ΡΠ΅ΠΌΡ 0404-2015-0021 Π² ΠΠ‘ΠΠ Π€ΠΠ
Improving accuracy and generalization performance of small-size recurrent neural networks applied to short-term load forecasting
The load forecasting of a coal mining enterprise is a complicated problem due to the irregular technological process of mining. It is necessary to apply models that can distinguish both cyclic components and complex rules in the energy consumption data that reflect the highly volatile technological process. For such tasks, Artificial Neural Networks demonstrate advanced performance. In recent years, the effectiveness of Artificial Neural Networks has been significantly improved thanks to new state-of-the-art architectures, training methods and approaches to reduce overfitting. In this paper, the Recurrent Neural Network architecture with a small-size model was applied to the short-term load forecasting of a coal mining enterprise. A single recurrent model was developed and trained for the entire four-year operational period of the enterprise, with significant changes in the energy consumption pattern during the period. This task was challenging since it required high-level generalization performance from the model. It was shown that the accuracy and generalization properties of small-size recurrent models can be significantly improved by the proper selection of the hyper-parameters and training method. The effectiveness of the proposed approach was validated using a real-case dataset. Β© 2020 by the authors. Licensee MDPI, Basel, Switzerland
Phantom scalar emission in the Kerr black hole spacetime
We study the absorption probability and Hawking radiation spectra of a
phantom scalar field in the Kerr black hole spacetime. We find that the
presence of the negative kinetic energy terms modifies the standard results in
the greybody factor, super-radiance and Hawking radiation. Comparing with the
usual scalar particle, the phantom scalar emission is enhanced in the black
hole spacetime.Comment: 11 pages, 6 figures, a revised version accepted for publication in
CQ
Data Mining Applied to Decision Support Systems for Power Transformersβ Health Diagnostics
This manuscript addresses the problem of technical state assessment of power transformers based on data preprocessing and machine learning. The initial dataset contains diagnostics results of the power transformers, which were collected from a variety of different data sources. It leads to dramatic degradation of the quality of the initial dataset, due to a substantial number of missing values. The problems of such real-life datasets are considered together with the performed efforts to find a balance between data quality and quantity. A data preprocessing method is proposed as a two-iteration data mining technology with simultaneous visualization of objectsβ observability in a form of an image of the dataset represented by a data area diagram. The visualization improves the decision-making quality in the course of the data preprocessing procedure. On the dataset collected by the authors, the two-iteration data preprocessing technology increased the dataset filling degree from 75% to 94%, thus the number of gaps that had to be filled in with the synthetic values was reduced by 2.5 times. The processed dataset was used to build machine-learning models for power transformersβ technical state classification. A comparative analysis of different machine learning models was carried out. The outperforming efficiency of ensembles of decision trees was validated for the fleet of high-voltage power equipment taken under consideration. The resulting classification-quality metric, namely, F1-score, was estimated to be 83%. Β© 2022 by the authors.Ministry of Education and Science of the Russian Federation,Β MinobrnaukaThe research funding from the Ministry of Science and Higher Education of the Russian Federation (Ural Federal University Program of Development within the Priority-2030 Program) is gratefully acknowledged
Supernovae - Optical Precursors of Short Gamma-Ray Bursts
The probability of observing "supernova - gamma-ray burst" (GRB) pair events
and recurrent GRBs from one galaxy in a time interval of several years has been
estimated. Supernova explosions in binary systems accompanied by the formation
of a short-lived pair of compact objects can be the sources of such events. If
a short GRB is generated during the collision of a pair, then approximately
each of ~300 short GRBs with redshift z must have an optical precursor - a
supernova in the observer's time interval <2(1+z)yr. If the supernova explosion
has the pattern of a hypernova, then a successive observation of long and short
GRBs is possible. The scenario for the generation of multiple GRBs in
collapsing galactic nuclei is also discussed.Comment: 12 pages, 1 figure; this paper has the e-precursor arXiv:1101.3298
[astro-ph.HE
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