Some problems of precise measurements of heat transfer coefficients in glass melts : Part 1. Measurements of effective conductivity

In the paper the method of measurements of the so-called effective conductivity of glass melts basing on characteristic of temperature gradient in a molten glass inside a refractory tank is analyzed. For this purpose a computer model based on the solution of the radiative transfer equation in a semitransparent medium was used. Among the papers on effective conductivity measurements published so far, only two contained enough numerical information on the details of measurement which permitted to perform the corresponding calculations. The authors of the present paper show what particular defects of experimental procedure could be the reason of surprising results reported in these publications, namely that the measured effective conductivity coefficient of a number of glasses was found to be lower than the radiative conductivity alone

Continuing the Traditions of Studying the Time of Troubles

The traditions of studying the Time of Troubles in Volgograd: history and modernity

Basic principles of building of E-network model of a complex technical system

Methodological bases of building of dynamic models of hybrid systems using principles of a «block» modelling are exposed on the basis of the E-network formalism. The presented methods are based on use of mechanisms of hierarchical interaction of dynamic model elements. Principles of organization of E-network hierarchical circuits with use of rigid and flexible structures are shown. The mechanism of interaction of static and dynamic components is specified

An experimental determination of the scale length of N2O in the soil of a grassland

Concentration profiles of N2O in a grassland soil and dynamic response curves to disturbance of the soil concentration (relaxation curves) were measured with a new membrane tube technique. Diffusive properties of the soil were derived from 222Rn measurements. The mathematical analysis of the relaxation curves yielded N2O uptake rates U soil diffusivities Ds, scale lengths z*, and production rates P at different levels under the surface. The following ranges were found during 2 days of measurements: Ds = (0.4–5) × 10−7 m2 s−1, U = (1–20) × 10−4 s−1, z* = 0.7–2.8 cm, and P = 0.02–4.4 ppb s−1. These values were used to reproduce the measured N2O concentration profiles with a one-dimensional diffusive transport model of N2O in the soil air-filled pore space and to deduce flux profiles. Bidirectional fluxes occurred with small deposition fluxes up to a few ppt ms−1 during intensive growing phases of the grass. Uptake rates were high enough that N2O produced at greater depth did not reach the atmosphere