38,649 research outputs found
Horizontally mounted solar collector
Solar energy is collected by using a vertical deflector assembly, a stationary reflector and a horizontally mounted solar collector. The deflector assembly contains a plurality of vanes which change the direction of the solar energy to the vertical, while constantly keeping the same side of the deflector facing the sun. The vertical rays are then reflected off the stationary reflector and are then absorbed by the collector
Centerscope
Centerscope, formerly Scope, was published by the Boston University Medical Center "to communicate the concern of the Medical Center for the development and maintenance of improved health care in contemporary society.
Conservation Equations of a Viscous, Heat-Conducting Fluid in Curvilinear Orthogonal Coordinates
Conservation equations of viscous heat conducting fluid in curvilinear orthogonal coordinate
A new technique for monitoring the water vapor in the atmosphere
In the correction of satellite Doppler data for tropospheric effects the precipitable water vapor (PWV) is inferred at the tracking site. The technique depends on: (1) an ephemeris for the satellite; (2) an analytic model for the refraction range effect that is good to a few centimeters; (3) Doppler data with noise level below 10 centimeters; and (4) a surface pressure/temperature measurement at the tracking site. The PWV is a by product of the computation necessary to correct the Doppler data for tropospheric effects. A formulation of the refraction integral minimizes the necessity for explicit water vapor, temperature and pressure profiles
Classifying the secondary component of the binary star W Aquilae
AIMS: The object W Aql is an asymptotic giant branch (AGB) star with a faint
companion. By determining more carefully the properties of the companion, we
hope to better constrain the properties of the AGB star. METHODS: We present
new spectral observations of the binary star W Aql at minimum and maximum
brightness and new photometric observations of W Aql at minimum brightness.
RESULTS: The composite spectrum near minimum light is predominantly from the
companion at wavelengths < 6000 . This spectrum can be
classified as F8 to G0, and the brightness of the companion is that of a dwarf
star. Therefore, it can be concluded that the companion is a main sequence
star. From this, we are able to constrain the mass of the AGB component to 1.04
- 3 and the mass of the W Aql system to 2.1 - 4.1 . Our
photometric results are broadly consistent with this classification and suggest
that the main sequence component suffers from approximately 2 mag of extinction
in the V band primarily due to the dust surrounding the AGB component.Comment: 5 pages, 1 figure, research not
Exploring the structure of a possible light scalar nonet
We first review the work of the Syracuse group, which uses an effective
chiral Lagrangian approach, on meson-meson scattering. An illustration
providing evidence for the existence of a strange scalar resonance of mass
around 900 MeV is given. An attempt to fit this together with a
similarly obtained and the well known and
into a nonet pattern suggests that the underlying structure is closer to a dual
quark-dual antiquark than to a quark-antiquark. A possible mechanism to explain
a next higher-in mass scalar meson nonet is also discussed. This involves
mixing between and states.Comment: 8 pages, 4 figures, invited talk at workshop "Possible Existence of
the Light Sigma Resonance and its Implications to Hadron Physics", Yukawa
Institute for Theoretical Physics, Kyoto, Japan, June 200
Light Scalar Mesons
We review how a certain effective chiral Lagrangian approach to pi pi
scattering, pi K scattering and eta-prime decay to eta pi pi provides evidence
for the existence of light scalars sigma(550) and kappa(900) as well as
describing the f0(980) and the a0(980). An attempt to fit these into a nonet
suggests that their structure is closer to a dual quark-dual antiquark than to
a quark-antiquark. A possible mechanism to explain the next higher mass scalar
nonet is also proposed.Comment: 10 pages, 4 figures, talk given at Hadron Physics: Effective Theories
of Low Energy QCD, Coimbra, Portugal, Sept. 199
Sulphur molecules in the circumstellar envelopes of M-type AGB stars
The sulphur compounds SO and SO have not been widely studied in the
circumstellar envelopes of asymptotic giant branch (AGB) stars. By presenting
and modelling a large number of SO and SO lines in the low mass-loss rate
M-type AGB star R Dor, and modelling the available lines of those molecules in
a further four M-type AGB stars, we aim to determine their circumstellar
abundances and distributions. We use a detailed radiative transfer analysis
based on the accelerated lambda iteration method to model circumstellar SO and
SO line emission and molecular data files for both SO and SO that are
more extensive than those previously available. Using 17 SO lines and 98 SO2
lines to constrain our models for R Dor, we find an SO abundance of
6.7x10 and an SO abundance of 5x10 with both species having
high abundances close to the star. We also modelled SO and found an
abundance of 3.1x10, giving an SO/SO ratio of 21.6. We
derive similar results for the circumstellar SO and SO abundances and their
distributions for the low mass-loss rate object W Hya. For these stars, the
circumstellar SO and SO abundances are much higher than predicted by
chemical models and these two species may account for all available sulphur.
For the higher mass-loss rate stars, we find shell-like SO distributions with
peak abundances that decrease and peak abundance radii that increase with
increasing mass-loss rate. The positions of the peak SO abundance agree very
well with the photodissociation radii of HO. We find evidence that SO is
most likely through the photodissociation of HO and the subsequent reaction
between S and OH. The S-bearing parent molecule appears not to be HS. The
SO models suggest an origin close to the star for this species, also
disagreeing with current chemical models.Comment: 25 page
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