205 research outputs found
Bubble formation and growth - Study of the boundary conditions at a liquid-vapor interface through irreversible thermodynamics Quarterly progress report, Mar. - May 1966
Nonequilibrium effect on vapor bubble growth determined in study of boundary conditions at liquid-vapor interfac
Bubble formation and growth - Study of the boundary conditions at a liquid-vapor interface through irreversible thermodynamics Quarterly progress report, Jun. - Aug. 1966
Steady state mercury evaporation experiment to measure transport coefficient in liquid-vapor interface boundary condition stud
Optimizing the performance of thermionic devices using energy filtering
Conventional thermionic power generators and refrigerators utilize a barrier
in the direction of transport to selectively transmit high-energy electrons.
Here we show that the energy spectrum of electrons transmitted in this way is
not optimal, and we derive the ideal energy spectrum for operation in the
maximum power regime. By using suitable energy filters, such as resonances in
quantum dots, the power of thermionic devices can, in principle, be improved by
an order of magnitude.Comment: 3 pages, 2 figure
Efficiency in nanostructured thermionic and thermoelectric devices
Advances in solid-state device design now allow the spectrum of transmitted
electrons in thermionic and thermoelectric devices to be engineered in ways
that were not previously possible. Here we show that the shape of the electron
energy spectrum in these devices has a significant impact on their performance.
We distinguish between traditional thermionic devices where electron momentum
is filtered in the direction of transport only and a second type, in which the
electron filtering occurs according to total electron momentum. Such 'total
momentum filtered' kr thermionic devices could potentially be implemented in,
for example, quantum dot superlattices. It is shown that whilst total momentum
filtered thermionic devices may achieve efficiency equal to the Carnot value,
traditional thermionic devices are limited to efficiency below this. Our second
main result is that the electronic efficiency of a device is not only improved
by reducing the width of the transmission filter as has previously been shown,
but also strongly depends on whether the transmission probability rises sharply
from zero to full transmission. The benefit of increasing efficiency through a
sharply rising transmission probability is that it can be achieved without
sacrificing device power, in contrast to the use of a narrow transmission
filter which can greatly reduce power. We show that devices which have a
sharply-rising transmission probability significantly outperform those which do
not and it is shown such transmission probabilities may be achieved with
practical single and multibarrier devices. Finally, we comment on the
implications of the effect the shape of the electron energy spectrum on the
efficiency of thermoelectric devices.Comment: 11 pages, 15 figure
Dynamic structure of motor cortical neuron coactivity carries behaviorally relevant information
AbstractSkillful, voluntary movements are underpinned by computations performed by networks of interconnected neurons in the primary motor cortex (M1). Computations are reflected by patterns of coactivity between neurons. Using pairwise spike time statistics, coactivity can be summarized as a functional network (FN). Here, we show that the structure of FNs constructed from an instructed-delay reach task in nonhuman primates is behaviorally specific: Low-dimensional embedding and graph alignment scores show that FNs constructed from closer target reach directions are also closer in network space. Using short intervals across a trial, we constructed temporal FNs and found that temporal FNs traverse a low-dimensional subspace in a reach-specific trajectory. Alignment scores show that FNs become separable and correspondingly decodable shortly after the Instruction cue. Finally, we observe that reciprocal connections in FNs transiently decrease following the Instruction cue, consistent with the hypothesis that information external to the recorded population temporarily alters the structure of the network at this moment
Applied thermionic research Final report, 1 Dec. 1967 - 1 Dec. 1968
Quadrupole mass spectrometer for thermochemical properties of cesium oxid
Applied thermionic research Quarterly progress report, 4 Mar. - 4 Jun. 1968
Oxidation products of cesium studied by differential thermal analysi
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