Values Of Effective Coefficient Research Articles

Definition of effective coefficients of thermal conductivity in spatially reinforced composites on the basis of energy criterion of equivalence

The models of thermal conductivity in fibrous spatially reinforced medium were developed at overall anisotropy of components; the approach is based on equality between dissipation in equivalent material and the considered composite. The calculated values of effective coefficients of thermal conductivity for two cases (unidirectional and cross-loaded) composites were compared with experimental data. Agreement between calculated and experimental data is satisfactory. It was demonstrated that developed models give the upper and lower estimates for effective coefficients of thermal conductivity in fibrous compositions.

Computer modeling of negative electrode operation in lithium-ion battery: Model of equal-sized grains, galvanostatic discharge mode, calculation of characteristic parameters

A computer simulation of the negative electrode (anode) operation in a lithium-ion battery is performed. A complete research program is carried out in accordance with the recommendations of the theory of porous electrodes: the “model of equal-sized grains of two types” was studied, percolation properties of the anode active layer were researched, values of effective coefficients were calculated for charge transfer and mass transport, a complete system of equations describing operation of the anode is presented. Two specific cases of galvanostatic mode of anode discharge are considered in detail: an “ideal” anode and anode with nanosize particles. Working anode parameters are calculated: optimum bulk concentration of graphite in the active layer, active layer thickness, time of complete anode discharge, its specific electric capacitance and final potential on the active/layer interelectrode space interface. Advisability of working with anodes with nanosize grains and electrolyte with enhanced specific conductivity is shown.

Amounts and character of distribution of impurities in zone-melted single-crystal lanthanum hexaboride

In the work described, lanthanum hexaboride single crystals were grown and refined by the levitation zone melting technique with induction heating. The amounts and character of distribution of impurities in the starting and zone-melted materials were determined by quantitative spectral analysis. It is shown that zone melting effectively purifies a starting lanthanum hexaboride powder from many contaminants. The effectiveness of removal of some low-melting-point and volatile elements is increased by their evaporation and escape in the gaseous form from the molten zone. Estimated values of effective coefficients of distribution of many impurities are given.