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  • 1995-1999  (8)
  • 1965-1969
  • 1998  (8)
  • 1
    Electronic Resource
    Electronic Resource
    Modeling the oxygen regime of stratified reservoirs (1998)
    Springer
    Power technology and engineering 32 (1998), S. 618-624 
    Details
    ISSN: 1570-1468
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Conclusions A mathematical model is proposed for the oxygen regime of a stratified reservoir. A model is based on representation of the reservoir on the whole or its layers individually as an ideal mixer. The thermal regime of a stratified reservoir is schematized by a two-layer model-epilimnion and hypolimnion, which provide the plane with a pronounced variation in water temperature (thermocline). In calculating the oxygen regime, the epilimnion and hypolimnion are considered individual reservoirs with their own water balance, which is linked, however, to the water balance of the reservoir on the whole. Characteristic features of the aeration and reaeration of the epilimnion and hypolimnion, and also the selectivity of water intake from the reservoir are considered here. Practical use of the model is illustrated in an example of the calculation of the oxygen regime of a hypothetical stratified reservoir, the characteristics of which are determined on the basis of field data derived from observations on the water bodies of the Zagorsk water-storage power plant. The proposed model can be used to predict the oxygen regime of stratified reservoirs and the ecological feasibility of nature-conserving measures directed toward improving the quality of their water and conserving fauna.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02446338
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Transformation of nonradiative recombination centers in GaAs/AlGaAs quantum well structures upon treatment in a CF4 plasma followed by low-temperature annealing (1998)
    Springer
    Semiconductors 32 (1998), S. 1293-1298 
    Details
    ISSN: 1063-7826
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The influence of low-temperature annealing on the photoluminescence of GaAs/AlGaAs single-quantum-well structures treated in a low-energy CF4 plasma is investigated. It is established that annealing at 160–300 °C causes a decrease of the photoluminescence intensity of the quantum wells located in the near-surface region, while annealing at 350–450 °C leads to partial restoration of their photoluminescence. The activation energy for the diffusion of plasma-produced point defects and the activation energy for the annealing of these defects are determined. These energies are equal to 150 and 540 meV, respectively. It is discovered that the photoluminescence of the quantum wells near the substrate, which had a low intensity in the as-grown sample, increases after treatment in the plasma and decreases after subsequent annealing monotonically with increasing annealing temperature. Repeated treatment in a CF4 plasma leads to a repeated increase in the photoluminescence intensity of these quantum wells. It is theorized that the defects induced by the CF4 plasma form complexes with defects introduced during growth and that these complexes are not recombination centers. After low-temperature annealing, the complexes dissociate, and the nonradiative recombination centers are recreated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.1187617
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Universal effective coupling constants for the generalized Heisenberg model (1998)
    Springer
    Physics of the solid state 40 (1998), S. 1169-1174 
    Details
    ISSN: 1063-7834
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The aim of this study is to find universal critical values of the effective dimensionless coupling constant g 6 and refined universal values g 4 for Heisenberg ferromagnets with n-component order parameters. These constants appear in the equation of state and determine the nonlinear susceptibilities χ 4 and χ 6 in the critical region. Calculations are made of the first three terms of the expansion of g 6 in powers of g 4 in the limits of O(n) symmetry three-dimensional λϕ 4 theory, the resultant series is resummed by the Padé-Borel method, and then by substituting the fixed point coordinates g 4 * in the resultant expression, numerical values of g 6 * are obtained for different n. These numbers g 4 * for n〉3 were determined from a six-loop expansion for the β-function resummed using the Padé-Borel-Leroy technique. An analysis of the accuracy of these g 6 * values showed that they may differ from the true values by no more than 1.6%. These values of g 6 * were compared with those obtained by the 1/n expansion method which allowed the level of accuracy of this method to be assessed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.1130512
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  • 4
    Electronic Resource
    Electronic Resource
    Self-consistent diffusion-controlled growth of nuclei from eutectic solutions (1998)
    Springer
    Physics of the solid state 40 (1998), S. 1467-1469 
    Details
    ISSN: 1063-7834
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A study is made of the dynamics of self-consistent motion and growth of spherical new-phase nuclei from a eutectic melt. The growth rate of nuclei is shown to be proportional to supersaturation in both components. Motion of a single nucleus in a concentration-gradient field and of a pair of nuclei in a self-consistent concentration field is investigated. The velocity of motion of the nucleus as a whole has been established to depend on the key parameters of the problem, namely, supersaturation, radii of the nuclei, and their separation. The force of mutual attraction between nuclei is estimated, and it is shown to be inversely proportional to the fifth power of their separation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.1130577
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    A flexible climate model for use in integrated assessments (1998)
    Springer
    Climate dynamics 14 (1998), S. 291-303 
    Details
    ISSN: 1432-0894
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract  Because of significant uncertainty in the behavior of the climate system, evaluations of the possible impact of an increase in greenhouse gas concentrations in the atmosphere require a large number of long-term climate simulations. Studies of this kind are impossible to carry out with coupled atmosphere ocean general circulation models (AOGCMs) because of their tremendous computer resource requirements. Here we describe a two dimensional (zonally averaged) atmospheric model coupled with a diffusive ocean model developed for use in the integrated framework of the Massachusetts Institute of Technology (MIT) Joint Program on the Science and Policy of Global Change. The 2-D model has been developed from the Goddard Institute for Space Studies (GISS) GCM and includes parametrizations of all the main physical processes. This allows it to reproduce many of the nonlinear interactions occurring in simulations with GCMs. Comparisons of the results of present-day climate simulations with observations show that the model reasonably reproduces the main features of the zonally averaged atmospheric structure and circulation. The model’s sensitivity can be varied by changing the magnitude of an inserted additional cloud feedback. Equilibrium responses of different versions of the 2-D model to an instantaneous doubling of atmospheric CO2 are compared with results of similar simulations with different AGCMs. It is shown that the additional cloud feedback does not lead to any physically inconsistent results. On the contrary, changes in climate variables such as precipitation and evaporation, and their dependencies on surface warming produced by different versions of the MIT 2-D model are similar to those shown by GCMs. By choosing appropriate values of the deep ocean diffusion coefficients, the transient behavior of different AOGCMs can be matched in simulations with the 2-D model, with a unique choice of diffusion coefficients allowing one to match the performance of a given AOGCM for a variety of transient forcing scenarios. Both surface warming and sea level rise due to thermal expansion of the deep ocean in response to a gradually increasing forcing are reasonably reproduced on time scales of 100–150 y. However a wide range of diffusion coefficients is needed to match the behavior of different AOGCMs. We use results of simulations with the 2-D model to show that the impact on climate change of the implied uncertainty in the rate of heat penetration into the deep ocean is comparable with that of other significant uncertainties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003820050224
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Equipment for cleaning cooling channels of the chamber of a rubber mixer (1998)
    Springer
    Chemical and petroleum engineering 34 (1998), S. 304-305 
    Details
    ISSN: 1573-8329
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02418797
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  • 7
    Electronic Resource
    Electronic Resource
    Surface hardening of low-carbon martensitic steels by boronizing (1998)
    Springer
    Metal science and heat treatment 40 (1998), S. 266-268 
    Details
    ISSN: 1573-8973
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A large group of low-carbon martensitic steels developed recently possesses some advantages that make them widely applicable in the industry. The main merit of these steels consists in the possibility of deformation-free quenching in air and welding in a nonheat-treated state. These features are accompanied by a deep hardenability and high strength characteristics of the products and semiproducts. However, when these steels are used to produce parts operating under the conditions of contact friction their surface hardness and wear resistance should be increased. Since such steels are relatively novel, the methods of their surface hardening are still being developed. The present work is devoted to determining the possibility of optimizing the process of diffusion boronizing of carbon martensitic steels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02474889
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  • 8
    Electronic Resource
    Electronic Resource
    Implication of sympathetic innervation of the heart in antiarrhythmic action of intra-atrial laser irradiation (1998)
    Springer
    Bulletin of experimental biology and medicine 126 (1998), S. 1106-1109 
    Details
    ISSN: 1573-8221
    Keywords: myocardial ischemia ; cardiac arrhythmias ; ventricular fibrillation ; laser irradiation ; sympathetic cardiac regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The role of sympathetic nervous system in the antiarrhythmic effect of intra-atrial laser irradiation (λ=632.8 nm) during myocardial ischemia was studied in acute experiments on Nembutal-anesthetized cats. Laser irradiation applied after bilateral, dextral, or sinistral transection of cardiac branches of stellate ganglia increased the number of ischemic rhythm disturbances that developed after occlusion of the circumflex branch of the left coronary artery. The maximum increase in the number of arrhythmias was observed after dextral transection, the occurrence of ventricular fibrillation being 100%. Bilateral transection provoked a larger number of ischemic rhythm disturbances than the sinistral transection. It is probable that the development of the antiarrhythmic effect of laser irradiation requires sustained sympathetic activity targeted at the nonischemic regions in the myocardium that could play a stabilizing role during local ischemic damage to the heart.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02447246
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    Paper (German National Licenses)
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