106 research outputs found
The thermal effect of radiative transfer in the atomic oxygen line near 63 mu
Thermal effect of radiative transfer in atomic oxygen lin
Possibility of Turbulence from a Post-Navier-Stokes Equation
We introduce corrections to the Navier-Stokes equation arising from the
transitions between molecular states and the injection of external energy. In
the simplest application of the proposed post Navier-Stokes equation, we find a
multi-valued velocity field and the immediate possibility of velocity reversal,
both features of turbulence
Specific features of space-time variations of ozone during the development of intensive tropical disturbances
An analysis of specific features of space-time variations of ozone in the tropical areas which has been performed on the basis of processing of the results of special expedition studies in the Atlantic and Pacific in 1987-1990 and the data of observations at the stations of the world ozonometric network over the 25-year period. The existence of a cause-and-effect relation has been revealed between the processes determining tropical cyclone (TC) development, and specific features of variations of the total content of ozone (TCO) and the vertical distribution of ozone (VDO) in the regions of TC action. Characteristic features of day-to-day and daily variations of TCO during TC development have been found. On the periphery of a developing TC, 1-4 days before it reaches the stage of storm, TCO increases, on average, by 5-8 percent, and a substantial increase in the concentration of ozone occurs in the middle and upper troposphere. The most probable physical mechanisms relating the observed specific features of ozone variations to TC evolution have been suggested. A hypothesis of the possibility of using ozone as an indicator for early prediction of TC development has been substantiated
Local heating method for growth of aligned carbon nanotubes at low ambient temperature
We use a highly localised resistive heating technique to grow vertically aligned multiwalled nanotube
films and aligned single-walled nanotubes on substrates with an average temperature of less than 100°C. The
temperature at the catalyst can easily be as high as 1000 °C but an extremely high temperature gradient
ensures that the surrounding chip is held at much lower temperatures, even as close as 1μm away from the
local heater. We demonstrate the influence of temperature on the height of multi-walled nanotube films,
illustrate the feasibility of sequential growth of single-walled nanotubes by switching between local heaters
and also show that nanotubes can be grown over temperature sensitive materials such as resist polymer
Local heating method for growth of aligned carbon nanotubes at low ambient temperature
We use a highly localised resistive heating technique to grow vertically aligned multiwalled nanotube
films and aligned single-walled nanotubes on substrates with an average temperature of less than 100oC. The
temperature at the catalyst can easily be as high as 1000 oC but an extremely high temperature gradient
ensures that the surrounding chip is held at much lower temperatures, even as close as 1μm away from the
local heater. We demonstrate the influence of temperature on the height of multi-walled nanotube films,
illustrate the feasibility of sequential growth of single-walled nanotubes by switching between local heaters
and also show that nanotubes can be grown over temperature sensitive materials such as resist polymer
In situ Raman studies of single-walled carbon nanotubes grown by local catalyst heating
Using in situ Raman spectroscopy we investigate single wall carbon nanotube growth on Mo electrodes,using a highly localized resistive heating technique. Small diameter semiconducting single wall nanotubesgrow very rapidly when the catalyst support is heated to a temperature of 800 C. The G/D ratioshows an interesting time-dependent behaviour. It first decreases, indicating the presence of amorphouscarbon and then significantly increases again after ca. 5 min growth while retaining the position andshape expected for predominantly semiconducting carbon nanotubes
Determination of the Bending Rigidity of Graphene via Electrostatic Actuation of Buckled Membranes
The small mass and atomic-scale thickness of graphene membranes make them
highly suitable for nanoelectromechanical devices such as e.g. mass sensors,
high frequency resonators or memory elements. Although only atomically thick,
many of the mechanical properties of graphene membranes can be described by
classical continuum mechanics. An important parameter for predicting the
performance and linearity of graphene nanoelectromechanical devices as well as
for describing ripple formation and other properties such as electron
scattering mechanisms, is the bending rigidity, {\kappa}. In spite of the
importance of this parameter it has so far only been estimated indirectly for
monolayer graphene from the phonon spectrum of graphite, estimated from AFM
measurements or predicted from ab initio calculations or bond-order potential
models. Here, we employ a new approach to the experimental determination of
{\kappa} by exploiting the snap-through instability in pre-buckled graphene
membranes. We demonstrate the reproducible fabrication of convex buckled
graphene membranes by controlling the thermal stress during the fabrication
procedure and show the abrupt switching from convex to concave geometry that
occurs when electrostatic pressure is applied via an underlying gate electrode.
The bending rigidity of bilayer graphene membranes under ambient conditions was
determined to be eV. Monolayers have significantly lower
{\kappa} than bilayers
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