Propagation of Acoustic Waves in Porous Media and their Reflection and Transmission at a Pure Fluid/Porous Medium Permeable Interface

International audienceWe find a sufficient condition of hyperbolicity for a differential system governing the motion of a onedimensional porous medium, so ensuring the existence of a solution for the associated Cauchy problem. We study propagation of linear waves impacting at a pure-fluid/porous-medium interface and we deduce novel expressions for the reflection and transmission coefficients in terms of the spectral properties of the governing differential system. We show three dimensional plots drawing reflection and transmission coefficients as functions of Biot's parameters. In such a way we propose an indirect method for measuring Biot's parameters when the measurement of the reflection and transmission coefficients associated to the traveling waves is possible

About the causes of deactivation of the nickel catalyst methane conversion in the course of its operation

The results of studies of the chemical, phase composition, and structure of the samples of lining materials, and conversion catalysts of natural gas used in the mine unit are outlined. Possible mechanism of nickel ablation from catalyst that caused the reduction of the specific active surface of the catalyst and consequently its activity is described

Results of a search for daily and annual variations of the Po-214 half-life at the two year observation period

The brief description of installation TAU-2 intended for long-term monitoring of the half-life value $\tau$ ($\tau_{1/2}$) of the $^{214}$Po is presented. The methods of measurement and processing of collected data are reported. The results of analysis of time series values $\tau$ with different time step are presented. Total of measurement time was equal to 590 days. Averaged value of the $^{214}$Po half-life was obtained $\tau=163.46\pm0.04$ $\mu$s. The annual variation with an amplitude $A=(8.9\pm2.3)\cdot10^{-4}$, solar-daily variation with an amplitude $A_{So}=(7.5\pm1.2)\cdot10^{-4}$, lunar-daily variation with an amplitude $A_L=(6.9\pm2.0)\cdot10^{-4}$ and sidereal-daily variation with an amplitude $A_S=(7.2\pm1.2)\cdot10^{-4}$ were found in a series of $\tau$ values. The maximal values of amplitude are observed at the moments when the projections of the installation Earth location velocity vectors toward the source of possible variation achieve its maximal magnitudes.Comment: Talk at The International Workshop on Prospects of Particle Physics: "Neutrino Physics and Astrophysics" February 1 - Ferbuary 8, 2015, Valday,Russia, 7 pages, 12 figure (to be published in PEPAN

Influence of certain types of phosphate raw materials on the technological process of production extraction phosphoric acid and complex fertilizers

Research on definition of phase structure of various sources of phosphate raw materials was carried out. The possible material compositions of the studied natural phosphate are calculated on the basis of cations and anions balance according to their charge. Comparative analyses of technological parameters of the production of phosphoric acid during the transition to alternative forms of phosphate raw materials is executed