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Solid oxide fuel cells (SOFCs) are expected to be widely applicable
for both small and large-scale power generation systems. The reason
is that the SOFC is simple, highly efficient, tolerant to
impurities, and can at least partially internally reform
hydrocarbon fuels. A multi-physics, multi-scale model structure is
proposed by integrating three submodels, i.e., a macro-continuum
model, a micro-scale model (random walk model) and an
atomistic-level model. This multi-scale model has the capability of
handling transport mechanisms on different length scales at the
same time. The coarsest macro-continuum model is first proposed to
simulate all energy transport processes in an
electrolyte-/anode-supported SOFC. Then a novel micro-level model
(random walk model) is developed to investigate the electrochemical
performance in a composite electrode. Finally, a multi-scale model
by combining the developed macro-level model and micro-level model
is proposed for a lower temperature SOFC. Based on this multi-scale
model, the dependence of electrochemical performance on the global
parameters and micro-structures is assessed for the entire fuel
cell stack.
Chilldown process is a complicated process involves unsteady
two-phase heat and mass transfer and initiates the cryogenic fluids
transport. To advance the understanding of this process, both
experimental and modeling investigations have been carried. The
chilldown process can be generally divided into three regions which
are associated with different flow regimes and heat transfer
mechanisms. Under low flow conditions, the two-phase flow during
chilldown is dispersed. The statistic feature of the liquid
filaments is studied and a model, in which the heat transfer at the
bottom is considered as a sum of vapor and liquid components, has
been developed for the dispersed flow film boiling. The bottom wall
heat flux is found to decrease under microgravity condition. A
cryogenic chilldown model has also been developed. The model
focuses on both vertical tube orientation and microgravity
chilldown and shows a good agreement with previous experimental
data.
Working memory (WM), which includes short-term memory and cognitive
control, has been found to be closely related to a wide range of
high-level cognitive abilities and academic achievement. Prior
studies showed children with attention-deficit/hyperactivity
disorder improved their WM and fluid intelligence through
computerized cognitive training (CCT) in a clinical setting. This
research examined whether regular middle-school students would
significantly improve their WM through CCT on WM; and if so,
whether increase in WM would lead to improved fluid intelligence
and science achievement. Two randomized pretest-posttest
control-group experimental studies were conducted to answer these
questions. Results showed CCT effectively improved regular
students' WM in a school setting, with more increase in short-term
memory than in cognitive control. No significant improvement was
observed in fluid intelligence and science achievement immediately
following training. Given the increasingly complex learning
environment in schools, using CCT to improve students' cognition
and academic learning has important implications for both
practitioners and researchers in education.
This report examines Pittsburgh Public Schools' implementation and
outcomes of the Pittsburgh Principal Incentive Program from school
years 2007-2008 through 2010-2011, how principals and other school
staff have responded to the reforms, and what outcomes accompanied
program implementation.
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