Lyubov V.K.,Lomonosov North Arctic Federal University |
Malygin P.V.,Lomonosov North Arctic Federal University |
Popov A.N.,Lomonosov North Arctic Federal University |
Popova E.I.,Lomonosov North Arctic Federal University
Thermal Engineering (English translation of Teploenergetika) | Year: 2015
A refined procedure for determining heat loss into the environment from heat-generating installations is presented that takes into account the state of their lining and heat insulation quality. The fraction of radiative component in the total amount of heat loss through the outer surfaces is determined. The results from experimental investigations of the thermal engineering and environmental performance characteristics of a foreign hot-water boiler in firing wood pellets are presented. A conclusion is drawn about the possibility of using such hot-water boilers for supplying heat to low-rise buildings, especially for the conditions of the North-Arctic region. The results from a thermal engineering investigation of wood pellets and furnace residue carried out on installations of a thermal analysis laboratory are presented together with the grain-size composition of fuel and indicators characterizing the mechanical strength of wood pellets. The velocity fields, flue gas flow rates, and soot particle concentrations are determined using the external filtration methods, and the composition of combustion products is investigated using a gas analyzer. The graphs of variation with time of boiler external surface temperature from the moment of achieving the nominal mode of operation and heat loss into the environment for stationary boilers are presented. © 2015, Maik Nauka-Interperiodica Publishing, all rights reserved.
Makarov D.N.,Lomonosov North Arctic Federal University |
Matveev V.I.,Lomonosov North Arctic Federal University
Journal of Experimental and Theoretical Physics | Year: 2014
We develop a method for calculating the spectra of reemission of ultrashort (attosecond and shorter) electromagnetic field pulses by neutral multielectron atoms with a nuclear charge from 1 to 92. The method makes it possible to exactly take into account the spatial nonuniformity of the field of an ultrashort pulse and photon momenta in reemission processes. The results are represented as analytical formulas with several coefficients and screening parameters tabulated for all atoms for which the electron densities can be described by the familiar Dirac-Hartree-Fock-Slater model. By way of example, the spectra of remission of ultrashort electromagnetic field pulses by carbon, silicon, germanium, tin, and lead atoms are calculated. © 2014, Pleiades Publishing, Inc.
Zvyagina N.V.,Lomonosov North Arctic Federal University |
Sokolova L.V.,Lomonosov North Arctic Federal University
Human Physiology | Year: 2013
Neurophysiological mechanisms of visual perception of verbalized and nonverbalized stimuli have been studied in girls (n = 89) and boys (n = 109) aged seven to eight years. It has been shown that, in children of this age, neurophysiological mechanisms of the visual perception system during the selection of verbalized and nonverbalized stimuli have similar organizations of functional rearrangements and are characterized by the general involvement of cortical areas and by the lack of clear specialization of the cerebral hemispheres. However, the choice of nonverbalized visual stimuli is characterized by a more pronounced generalization of the functional interaction between cortical areas and by the increased spectral power of the EEG's high-frequency components in anterior associative areas. The increased spatial synchronization in the EEG θ- and β bands in the frontal areas emphasizes the contribution of these structures to the analysis and processing of visual stimuli at this stage of development. Differences in the neurophysiological mechanisms of visual perception in boys and girls have been detected. Spatial and temporal organizations of bioelectric activity (BEA) of the brain in girls performing visual tasks is characterized by a stronger and more varied ipsi- and contralateral statistical relationships in the fronto-occipital direction and displacement of interaction centers to the left hemisphere. In boys perceiving verbalized and nonverbalized visual stimuli, a greater contribution of posterocentral cortical areas has been observed. The detected differences are considered to reflect a greater maturity of identification mechanisms in girls aged seven to eight years as compared to boys. © 2013 Pleiades Publishing, Ltd.