Исследование спектральных характеристик тепловых свойств многослойных металлических материалов
The possibility of using periodic pulsed laser radiation for spectral analysis of the thermal properties of multilayer metallic materials is studied. Pulse and frequency characteristics of samples are found. An expression for the transfer constant of a thermal signal in multilayer materials is obtained. A parametric model is used to determine the thermal conductivity of the interface in a three_layer Mo(1 μm)–W(48 μm)–Mo(1 μm) sample from the amplitude–frequency characteristic measured before and after irradiation by 9_MeV electrons.
A method is developed to analyze the state of the interface in a multilayer metallic system; it is based on spectral analysis of a heat_transfer coefficient. A coefficient of correlation is used to find the relation between the spectral characteristics and the thermal conductivity of the interphase interface. The change in the coefficient of correlation induced by 10_MeV electron irradiation of a multilayer W–Mo system is studied.
The irradiation of type EP-838 austenitic stainless steel by electrons in a high-voltage microscope results in decomposition of the solid solution. The decomposition takes place in two stages. The first stage occurs as a spinodal decomposition which tends to form a lattice of rod-like precipitates along the  direction. The second stage is connected with the formation of needle-shaped precipitates oriented along the  direction.
Within the framework of model calculations the possibility of occurrence of the ion-acoustic oscillation instability in a plasma without current and particle fluxes, but with an anisotropic distribution function, which corresponds to heat flux is shown. The model distribution function was selected taking into account the medium conditions. The increment of ion-acoustic oscillation is investigated as functional of the distribution function parameters. The threshold condition for the anisotropic part of the distribution function, under which the build-up of ion-acoustic oscillation with the wave vector opposite to the heat flux begins is studied. The critical heat flux, which corresponds to the threshold of ion-acoustic instability, is determined. For the solar conditions, the critical heat flux proved to be close to the heat flux from the corona into the chromosphere on the boundary of the transition region. The estimations show that outside of active regions and even in active regions with weaker magnetic fields ion-acoustic turbulence can be responsible for the formation of the sharp temperature jump. The generalized Wiedemann-Franz law for a non-isothermic quasi-neutral plasma with developed ion-acoustic turbulence is discussed. This law determines the relationship between electrical and thermal conductivities in a plasma with well-developed ion-acoustic turbulence. The anomalously low thermal conductivity responsible to the formation of high temperature gradients in the zone of the temperature jump is explained. The results are used to explain some properties of stellar atmosphere transition regions.
This volume presents new results in the study and optimization of information transmission models in telecommunication networks using different approaches, mainly based on theiries of queueing systems and queueing networks .
The paper provides a number of proposed draft operational guidelines for technology measurement and includes a number of tentative technology definitions to be used for statistical purposes, principles for identification and classification of potentially growing technology areas, suggestions on the survey strategies and indicators. These are the key components of an internationally harmonized framework for collecting and interpreting technology data that would need to be further developed through a broader consultation process. A summary of definitions of technology already available in OECD manuals and the stocktaking results are provided in the Annex section.