Browsing by Author "Stepanyants, YA"

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    Application of acoustical methods to the measurement of water content in sand
    (Australian Nuclear Science and Technology Organisation, 2000-10) Nazarov, VE; Radostin, AV; Stepanyants, YA; Bennett, JW
    Results of laboratory experiments on the propagation of high-frequency acoustic waves (f = 100 kHz) in a glass tube filled with river sand are presented. Several sand samples have been used with different water content: dry unsaturated and completely water saturated. It is shown that the dissipative coefficient of acoustic waves decreases with increasing wave amplitude. This 'self-brightening' phenomenon takes place over the whole range of moisture content from zero to 100% but its degree of manifestation depends on the moisture content. The exponent of the dissipative nonlinearity α is found to be the most sensitive parameter to the moisture content and is determined on the basis of measurements. It is considered to be a good indicator of water content in porous media and provides an opportunity to measure water content in such materials indirectly by means of an acoustic method. A simple phenomenological model is presented to explain the experimental results.
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    Model for the description of oxidation in sulfidic waste rock dumps.
    (Australian Nuclear Science and Technology Organisation, 2000-03) Pantelis, G; Ritchie, AIM; Stepanyants, YA; Bennett, JW
    Basic mathematical equations which describe the processes of sulfide oxidation and gas and water transport in waste rock dumps are presented and discussed. The governing equations account for gas and water flow vaporisation and condensation with latent heat effects heat transport and mass balance. Gas water and solid phases are assumed to be in local thermal equilibrium at all times. Air is approximated as an ideal three-component gas. Different semi-empirical relationships between physical values are used: Darcy's law for fluid flow ideal gas law the Van Genuchten formula for the relationship between degree of water saturation and pressure head Mualem's formula for the relative hydraulic conductivity as a function of pressure head etc. Some important global quantities such as the fraction of sulfide sulfur oxidised and the global oxidation rate are defined and considered as functions of time. The full set of equations is collected and presented in explicit form convenient for further numerical modelling. The glossary of some technical terms and the table of definitions of the main parameters as well as their units and characteristic values are displayed.