27,397 research outputs found
Apparatus for making curved reflectors Patent
Forming mold for polishing and machining curved solar magnesium reflector with reinforcing rib
Process sequence produces strong, lightweight reflectors of excellent quality
Large compound curved surfaces for collecting and concentrating radiation are fabricated by the use of several common machining and forming processes. Lightweight sectors are assembled into large reflectors. With this concept of fabrication, integrally stiffened reflective sectors up to 25 square feet in area have been produced
Method and apparatus for making curved reflectors Patent
Fabrication of curved reflector segments for solar mirro
Interfaces between highly incompatible polymers of different stiffness: Monte Carlo simulations and self-consistent field calculations
We investigate interfacial properties between two highly incompatible
polymers of different stiffness. The extensive Monte Carlo simulations of the
binary polymer melt yield detailed interfacial profiles and the interfacial
tension via an analysis of capillary fluctuations. We extract an effective
Flory-Huggins parameter from the simulations, which is used in self-consistent
field calculations. These take due account of the chain architecture via a
partial enumeration of the single chain partition function, using chain
conformations obtained by Monte Carlo simulations of the pure phases. The
agreement between the simulations and self-consistent field calculations is
almost quantitative, however we find deviations from the predictions of the
Gaussian chain model for high incompatibilities or large stiffness. The
interfacial width at very high incompatibilities is smaller than the prediction
of the Gaussian chain model, and decreases upon increasing the statistical
segment length of the semi-flexible component.Comment: to appear in J.Chem.Phy
The Relation between Solar Eruption Topologies and Observed Flare Features I: Flare Ribbons
In this paper we present a topological magnetic field investigation of seven
two-ribbon flares in sigmoidal active regions observed with Hinode, STEREO, and
SDO. We first derive the 3D coronal magnetic field structure of all regions
using marginally unstable 3D coronal magnetic field models created with the
flux rope insertion method. The unstable models have been shown to be a good
model of the flaring magnetic field configurations. Regions are selected based
on their pre-flare configurations along with the appearance and observational
coverage of flare ribbons, and the model is constrained using pre-flare
features observed in extreme ultraviolet and X-ray passbands. We perform a
topology analysis of the models by computing the squashing factor, Q, in order
to determine the locations of prominent quasi-separatrix layers (QSLs). QSLs
from these maps are compared to flare ribbons at their full extents. We show
that in all cases the straight segments of the two J-shaped ribbons are matched
very well by the flux-rope-related QSLs, and the matches to the hooked segments
are less consistent but still good for most cases. In addition, we show that
these QSLs overlay ridges in the electric current density maps. This study is
the largest sample of regions with QSLs derived from 3D coronal magnetic field
models, and it shows that the magnetofrictional modeling technique that we
employ gives a very good representation of flaring regions, with the power to
predict flare ribbon locations in the event of a flare following the time of
the model
Neutron-irradiation effects in LaO0.9F0.1FeAs superconductor
The effect of atomic disorder induced by neutrons irradiation on
superconducting and normal state properties of polycrystalline LaFeAsO_0.9F_0.1
was investigated. The irradiation of the sample by a moderate neutron fluence F
= 1.6*1019 cm^-2 at Tirr = 50 +- 10 C leads to the suppression of
superconductivity which recovers almost completely after annealing at
temperatures Tann < 750 C. It is shown that the reduction of superconducting
transition temperature Tc under atomic disordering is not determined solely by
the value of Hall concentration nH, i.e. doping level, but is governed by the
reduction of electronic relaxation time. This behavior can be described
qualitatively by universal Abrikosov-Gorkov equation which presents evidence on
the anomalous type of electrons pairing in Fe-based superconductors.Comment: 8 pages, 11 figure
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