477 research outputs found
Kinetics of dislocation ensembles in deformable irradiated materials
The development of plastic instability in the initial deformation stages of irradiated materials is studied. The dependence of the fraction of dislocations which overcome obstacles in the dynamic regime (dislocation ‘‘channeling’’) on the degree of radiation hardening (irradiation dose) and the dislocation velocity is analyzed. It is shown that this effect plays a role in radiation embrittlement of reactor materialsyesBelgorod State Universit
Accuracy of one-dimensional collision integral in the rigid spheres approximation
The accuracy of calculation of spectral line shapes in one-dimensional
approximation is studied analytically in several limiting cases for arbitrary
collision kernel and numerically in the rigid spheres model. It is shown that
the deviation of the line profile is maximal in the center of the line in case
of large perturber mass and intermediate values of collision frequency. For
moderate masses of buffer molecules the error of one-dimensional approximation
is found not to exceed 5%.Comment: LaTeX, 24 pages, 8 figure
Relativistic Energy Density Functional Description of Shape Transition in Superheavy Nuclei
Relativistic energy density functionals (REDF) provide a complete and
accurate, global description of nuclear structure phenomena. A modern
semi-empirical functional, adjusted to the nuclear matter equation of state and
to empirical masses of deformed nuclei, is applied to studies of shapes of
superheavy nuclei. The theoretical framework is tested in a comparison of
calculated masses, quadrupole deformations, and potential energy barriers to
available data on actinide isotopes. Self-consistent mean-field calculations
predict a variety of spherical, axial and triaxial shapes of long-lived
superheavy nuclei, and their alpha-decay energies and half-lives are compared
to data. A microscopic, REDF-based, quadrupole collective Hamiltonian model is
used to study the effect of explicit treatment of collective correlations in
the calculation of Q{\alpha} values and half-lives.Comment: 23 pages, 10 figure
Role of internal stresses in the localization of plastic flow of irradiated materials
The collective behavior of dislocations in irradiated materials is studied using the kinetic equation for the dislocation density, taking account of a Burgers-type nonlinearity. It is shown that the degree of dislocation localization in slip bands is higher in the irradiated materials than in the unirradiated materialsyesBelgorod State Universit
Bulk Nanocrystalline Thermoelectrics Based on Bi-Sb-Te Solid Solution
A nanopowder from p-Bi-Sb-Te with particles ~ 10 nm were fabricated by the
ball milling using different technological modes. Cold and hot pressing at
different conditions and also SPS process were used for consolidation of the
powder into a bulk nanostructure and nanocomposites. The main factors allowing
slowing-down of the growth of nanograins as a result of recrystallization are
the reduction of the temperature and of the duration of the pressing, the
increase of the pressure, as well as addition of small value additives (like
MoS2, thermally expanded graphite or fullerenes). It was reached the
thermoelectric figure of merit ZT=1.22 (at 360 K) in the bulk nanostructure
Bi0,4Sb1,6Te3 fabricated by SPS method. Some mechanisms of the improvement of
the thermoelectric efficiency in bulk nanocrystalline semiconductors based on
BixSb2-xTe3 are studied theoretically. The reduction of nanograin size can lead
to improvement of the thermoelectric figure of merit. The theoretical
dependence of the electric and heat conductivities and the thermoelectric power
as the function of nanograins size in BixSb2-xTe3 bulk nanostructure are quite
accurately correlates with the experimental data.Comment: 35 pages, 24 figures, 4 tables, 52 reference
On athermic mechanism of materials radiation embrittlement
To elucidate the mehanisms of radiation embrittlement of materials the temperature dependence of mechanical properties of irradiated materials has been studiedyesBelgorod State Universit
Photometric observations of the supernova 2009nr
We present the results of our UBVRI CCD photometry for the second brightest
supernova of 2009, SN 2009nr, discovered during a sky survey with the
telescopes of the MASTER robotic network. Its light and color curves and
bolometric light curves have been constructed. The light-curve parameters and
the maximum luminosity have been determined. SN 2009nr is shown to be similar
in light-curve shape and maximum luminosity to SN 1991T, which is the prototype
of the class of supernovae Ia with an enhanced luminosity. SN 2009nr exploded
far from the center of the spiral galaxy UGC 8255 and most likely belongs to
its old halo population. We hypothesize that this explosion is a consequence of
the merger of white dwarfs
Steppe rodents at the edge of their range: A case study of Spalax microphthalmus in the north of Ukraine
Based on results obtained during 2000–2018 by field research, polls of colleagues, and OSINT analysis, features of distribution of the greater mole rat Spalax microphthalmus in the eastern forest steppe of Ukraine were considered. The studied part of the species’ range is unique and represents the northern range edge of the entire Spalacidae family and of European steppe faunal assemblages in general. In total, data on 146 record localities were amassed, including 13 localities in the fragmented and 133 in the continuous part of the range. The offshoots of the Central Russian Upland in the valley of the Psel river (east of Sumy Oblast) are the sites with the highest density of settlements, while the species’ type biotopes are steppe balka slopes. The abundance of the greater mole rat decreased from the east to the west, and its colonies are the most fragmented along the Dnipro River. The species occurs in steppe and meadow habitats of an area of at least 20–50 ha. Analysis of the current and former distribution of the greater mole rat revealed that the species range contracts from the west; earlier it was a common species in different regions of the Middle Dnipro Area (including Kyiv city), but the current range edge runs along the line connecting Buryn – Nedryhailiv – Lokhvytsia – Myrhorod – Hadiach – Zinkiv – Zaliznychne. Isolated settlements exist in adjacent territories, particularly in Ichnia Raion of Chernihiv Oblast, and Lubny, Khorol, and Kobeliaky Raions of Poltava Oblast. The study showed that the species’ range contracted by two times to 35,000 km2 for the last 100 years, which includes only 430,000 ha of suitable habitats (15% of the range), allowing the existence here of 86,000–215,000 individuals. In fact, the species remained only in habitats that have been minimally affected by arable farming and other forms of active agricultural use. Besides, the species shows a clear confinement to habitats located near human settlements such as untilled lands, pastures with moderate grazing, waste and neglected lands, which constitute a separate group of transformed and semi-natural habitats. Formally, this allows the greater mole rat to be considered as a synanthropic species, because its inhabited biotopes, beside the zone of offshoots of the Central Russian Upland, have remained only near villages and along roads. The species also has an important biocoenotic role due to its burrowing activity and as prey of predatory birds (e.g., of the long-legged buzzard and Eurasian eagle owl) and mammals. The feeding period of the offspring of these predators generally coincides with the aboveground activity of mole rats, which lasts during May–July with a peak in June. Aboveground activity is mainly related to the resettlement of mole rats to new sites and dispersal of the young, due to which they became victims of predators
Методические аспекты повышения качества услуг в сфере транспортной логистики
Розробка методичних аспектів підвищення якості обслуговування в транспортно-логістичних компаніях на основі вимог міжнародних стандартів якості ISO 9000:2008 з використанням простих інструментів контролю якості.Article on developing methodological aspects of service quality improvement in transportation and logistics companies, based on the requirements of international quality standards ISO 9000:2008, using simple tools of quality control. This paper defines the key issues to improve the quality of logistics services, approaches to the selection of methods and tools to ensure continuous improvement of transport and logistics companies. The mechanisms of implementing the requirements of the standard relating to the measurement of the quality of the provision of logistics services. The essence of the method and the role of «six sigma» in implementing the concept of «zero defects». Defines the approaches to the selection criteria and evaluation methodology for outsourcing companies, and recommendations on the use of quality control tools to improve the quality of logistics services.Разработка методических аспектов повышения качества обслуживания в транспортно-логистических компаниях на основе требований международных стандартов качества ISO 9000:2008 с использованием простых инструментов контроля качества
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