32,254 research outputs found
Convergence and Optimality of Adaptive Mixed Finite Element Methods
The convergence and optimality of adaptive mixed finite element methods for
the Poisson equation are established in this paper. The main difficulty for
mixed finite element methods is the lack of minimization principle and thus the
failure of orthogonality. A quasi-orthogonality property is proved using the
fact that the error is orthogonal to the divergence free subspace, while the
part of the error that is not divergence free can be bounded by the data
oscillation using a discrete stability result. This discrete stability result
is also used to get a localized discrete upper bound which is crucial for the
proof of the optimality of the adaptive approximation
On the Computation Power of Name Parameterization in Higher-order Processes
Parameterization extends higher-order processes with the capability of
abstraction (akin to that in lambda-calculus), and is known to be able to
enhance the expressiveness. This paper focuses on the parameterization of
names, i.e. a construct that maps a name to a process, in the higher-order
setting. We provide two results concerning its computation capacity. First,
name parameterization brings up a complete model, in the sense that it can
express an elementary interactive model with built-in recursive functions.
Second, we compare name parameterization with the well-known pi-calculus, and
provide two encodings between them.Comment: In Proceedings ICE 2015, arXiv:1508.0459
Star formation associated with a large-scale infrared bubble
Using the data from the Galactic Ring Survey (GRS) and Galactic Legacy
Infrared Mid-Plane Survey Extraordinaire (GLIMPSE), we performed a study for a
large-scale infrared bubble with a size of about 16 pc at a distance of 2.0
kpc. We present the 12CO J=1-0, 13CO J=1-0 and C18O J=1-0 observations of HII
region G53.54-0.01 (Sh2-82) obtained at the the Purple Mountain Observation
(PMO) 13.7 m radio telescope to investigate the detailed distribution of
associated molecular material. The large-scale infrared bubble shows a
half-shell morphology at 8 um. H II regions G53.54-0.01, G53.64+0.24, and
G54.09-0.06 are situated on the bubble. Comparing the radio recombination line
velocities and associated 13CO J=1-0 components of the three H II regions, we
found that the 8 um emission associated with H II region G53.54-0.01 should
belong to the foreground emission, and only overlap with the large-scale
infrared bubble in the line of sight. Three extended green objects (EGOs, the
candidate massive young stellar objects), as well as three H II regions and two
small-scale bubbles are found located in the G54.09-0.06 complex, indicating an
active massive star-forming region. C18O J=1-0 emission presents four cloud
clumps on the northeastern border of H II region G53.54-0.01. Via comparing the
spectral profiles of 12CO J=1-0, 13CO J=1-0, and C18O J=1-0 peak at each clump,
we found the collected gas in the three clumps, except for the clump coincided
with a massive YSO (IRAS 19282+1814). Using the evolutive model of H II region,
we derived that the age of H II region G53.54-0.01 is 1.5*10^6 yr. The
significant enhancement of several Class I and Class II YSOs around G53.54-0.01
indicates the presence of some recently formed stars, which may be triggered by
this H II region through the collect and collapse (CC) process.Comment: 9 pages, 6 figures, accepted for publication in A&
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