Ceramic fuel cells using novel proton-conducting BaCe0.5Zr0.3Y0.1Yb0.05Zn0.05O3-δ electrolyte

Journal of Solid State Electrochemistry - Protonic ceramic fuel cells have become extremely interesting due to their high power output at the intermediate temperature range...     

Helical chains of [MO5Cl] octahedra – Three compounds in the new family AEM2Te3O8Cl2 (AE = Ca,Sr and M = Co,Ni)

The compounds CaCo₂Te₃O₈Cl₂, SrCo₂Te₃O₈Cl₂ and SrNi₂Te₃O₈Cl₂ were synthesized via solid–gas reactions and investigated using single-crystal X-ray diffraction. While the compound CaCo₂Te₃O₈Cl₂ formed large enough single crystals to allow for a detailed structural analysis, crystals of the Sr-containing compounds yielded evidence that they are isostructural. CaCo₂Te₃O₈Cl₂ crystallizes in the monoclinic system, space group P2₁/c, a = 6.537(2) Å, b = 9.088(2) Å, c = 19.500(9) Å, β = 113.36(4)°, Z = 4. It exhibits [CoO₅Cl] helical chains along the [010] direction, connected by [CaO₈] polyhedra, [TeO₃E] tetrahedra and [TeO₄E] trigonal bipyramids (the lone pair of electrons on Te^IV is designated as E) to form a layer. The layers are held together only by weak van der Waals forces; the shortest interlayer distance is a Te?Cl contact of 3.432(4) Å.     

Analytical results on two-phase rows in ducts

A deterministic stochastic approach is successfully applied to the investigation of some problems of the fluid-dynamics of two-phase systems. The method follows the guidelines of the theory of differential equations with random initial conditions.Dusty gas flows and bubble flows are considered in circumstances where the action of the particulate matter on the fluid flow field is negligible. In all the cases, collisions between particles of the disperse phase are neglected. As significant applications, the entrance flow of dust particles in a tube and the behaviour of a population of bubbles imbedded in a pipe-flow subject to an abrupt area, change are considered. The probable distributions of the particles are evaluated as functions of assigned statistical distributions of the objects at the initial time.

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Analytische Ergebnisse von Zweiphasen-Strömungen in Kanälen

Zusammenfassung Ein deterministisch-stochastischer Ansatz wird erfolgreich auf die Untersuchung einiger Strömungsprobleme von Zweiphasensystemen angewandt. Die Methode entspricht der Theorie von Differential-gleichungen mit zufälligen Anfangsproblemen.Staub-Gas-Strömungen und Blasen-Strömungen werden unter Bedingungen behandelt, bei denen der Einfluß des betreffenden Stoffes auf das Strömungsfeld vernachlässigt werden kann. In allen Fällen werden auch Kollisionen zwischen Partikeln der dispersen Phase vernachlässigt. Als kennzeichnende Anwendungen werden die Eintrittsströmungen von Staub in ein Rohr und das Verhalten eines Blasenschwarmes an einer sprunghaften Querschnittsveränderung eines Rohres behandelt. Die wahrscheinlichen Teilchenverteilungen werden als Funktionen bestimmter Anfangsverteilungen ermittelt.

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Nomenclature A normalization factor - A,b,c,kj,G,, dimensionless quantities defined in the text - h _a/_c - H _w/_a - J operator defined at page 2 - K Boltzmann constant - p dimensionless pressure - P probability density - p probability - r⁺ radius of the tube, reference length - R radial co-ordinate (dimensionless) - Re Reynolds number of the relative motion of the particles with respect to the fluid - t⁺ reference time, r⁺ /U⁺ - t time (dimensionless) - U⁺ reference velocity - U_a,U_r axial and radial velocity components, respectively, of the fluid flow - 183-01 state vector of a particle - V_a,V_r axial and radial velocity components respectively of a particle - Z dimensionless axial co-ordinate along the tube - viscosity - mass density - diameter of a particle, dimensionless with respect to r⁺ Indexes ()_a air - ()_c coal - ()_t at the time t - ()_w water - ()_o at the time t=o