We evaluated the use of pressure support to compensate for the added inspiratory work of breathing due to the resistances of endotracheal tubes and a ventilator demand-valve system for continuous positive airway pressure (CPAP). A mechanical model was used to simulate spontaneous breathing at five respiratory rates through 7-mm, 8-mm, and 9-mm endotracheal tubes with and without a ventilator de...

In 3 experiments, the authors examined mathematical problem solving performance under pressure. In Experiment 1, pressure harmed performance on only unpracticed problems with heavy working memory demands. In Experiment 2, such high-demand problems were practiced until their answers were directly retrieved from memory. This eliminated choking under pressure. Experiment 3 dissociated practice on ...

The operation and the development of power system networks introduce new types stability problems. effect generation consumption on frequency can be described as a demand/generation imbalance resulting from sudden increase/decrease in demand and/or generation. This paper investigates impact loss transient behaviour grid frequency. A simplified model is proposed to examine change main parameters...

Wall displacements and ground pressure acting on the lining of a tunnel increase with time. These time-dependent deformations are both due to face advance effect and to the time-dependent behavior of the rock mass.  Viscoelastic materials exhibit both viscous and elastic behaviors. Thorough this study, the effect of different linear viscoelastic models including Maxwell, Kelvin and Kelvin-Voigt...