Psychological Peculiarities of the Foreign Languages Maste-ring by the Primary School Children

Статтю присвячено актуальній психологічній проблемі − дослідженню психологічних особливостей оволодіння іноземною мовою дітьми молодшого шкільного віку з позиції когнітивного та комунікативного підходів. The article is devoted to the psychological peculiarities of foreign languages mastering by the primary school children

Ice crystallization during cold-start of a proton-exchange-membrane fuel cell

Under subfreezing conditions, ice forms in the gas-diffusion (GDL) and catalyst layers (CL) of proton-exchange-membrane fuel cells (PEMFCs), drastically reducing cell performance. Although a number of strategies exist to prevent ice formation, there is little fundamental understanding of ice-crystallization mechanisms and kinetics within PEMFC components. We incorporate recently developed ice-crystallization kinetic expressions (1-3) within the CL and GDL of a simplified 1-D transient PEMFC cold-start model. To investigate the importance of ice-crystallization kinetics, we compare liquid-water and ice saturations, and cell-failure time predicted using our kinetic rate expression relative to that predicted using a thermodynamic-based approach. We identify conditions under which ice-crystallization kinetics is critical and elucidate the impact of freezing kinetics on low-temperature PEMFC operation. © The Electrochemical Society

Known and new results on absolute convergence of Fourier integrals

New sufficient conditions for representation of a function via the absolutely convergent Fourier integral are obtained in the paper. In the main result, Theorem 1.1, this is controlled by the behavior near infinity of both the function and its derivative. This result is extended to any dimension d >= 2