15,734 research outputs found
Parallel Graph Decompositions Using Random Shifts
We show an improved parallel algorithm for decomposing an undirected
unweighted graph into small diameter pieces with a small fraction of the edges
in between. These decompositions form critical subroutines in a number of graph
algorithms. Our algorithm builds upon the shifted shortest path approach
introduced in [Blelloch, Gupta, Koutis, Miller, Peng, Tangwongsan, SPAA 2011].
By combining various stages of the previous algorithm, we obtain a
significantly simpler algorithm with the same asymptotic guarantees as the best
sequential algorithm
Improved Parallel Algorithms for Spanners and Hopsets
We use exponential start time clustering to design faster and more
work-efficient parallel graph algorithms involving distances. Previous
algorithms usually rely on graph decomposition routines with strict
restrictions on the diameters of the decomposed pieces. We weaken these bounds
in favor of stronger local probabilistic guarantees. This allows more direct
analyses of the overall process, giving: * Linear work parallel algorithms that
construct spanners with stretch and size in unweighted
graphs, and size in weighted graphs. * Hopsets that lead
to the first parallel algorithm for approximating shortest paths in undirected
graphs with work
P/N InP homojunction solar cells by LPE and MOCVD techniques
P/N InP homojunction solar cells have been prepared by using both liquid phase epitaxy (LPE) and metallorganic chemical vapor deposition (MOCVD) growth techniques. A heavily doped p-In sub 0.53Ga sub 0.47As contacting layer was incorporated into the cell structure to improve the fill factor and to eliminate surface spiking at the front surface. The best conversion efficiencies (total area) obtained under AM 1 illumination are 14.2 percent for a LPE cell and 15.4 percent for a MOCVD cell
Recognizing and Curating Photo Albums via Event-Specific Image Importance
Automatic organization of personal photos is a problem with many real world
ap- plications, and can be divided into two main tasks: recognizing the event
type of the photo collection, and selecting interesting images from the
collection. In this paper, we attempt to simultaneously solve both tasks:
album-wise event recognition and image- wise importance prediction. We
collected an album dataset with both event type labels and image importance
labels, refined from an existing CUFED dataset. We propose a hybrid system
consisting of three parts: A siamese network-based event-specific image
importance prediction, a Convolutional Neural Network (CNN) that recognizes the
event type, and a Long Short-Term Memory (LSTM)-based sequence level event
recognizer. We propose an iterative updating procedure for event type and image
importance score prediction. We experimentally verified that image importance
score prediction and event type recognition can each help the performance of
the other.Comment: Accepted as oral in BMVC 201
Emoji Disorder
The introduction of emoji to language creates a universal form of communication through expression. The thesis posits that with the contemporary context of a rising digital and visual language, the elastic architectural design language has the capability to be updated. The updated design language is translated from the existing context of emoji and reflects its pragmatics and characteristics. The duck, based on form, and the decorated shed, based on signage, are no longer adequate to project meaning on architecture. The symbolic language of emojis calls for a new model: the duckerated shed. This thesis will use the house typology as a testing ground to test this new language
Anomalous high energy dispersion in photoemission spectra from insulating cuprates
Angle resolved photoelectron spectroscopic measurements have been performed
on an insulating cuprate Ca_2CuO_2Cl_2. High resolution data taken along the
\Gamma to (pi,pi) cut show an additional dispersive feature that merges with
the known dispersion of the lowest binding energy feature, which follows the
usual strongly renormalized dispersion of ~0.35 eV. This higher energy part
reveals a dispersion that is very close to the unrenormalized band predicted by
band theory. A transfer of spectral weight from the low energy feature to the
high energy feature is observed as the \Gamma point is approached. By comparing
with theoretical calculations the high energy feature observed here
demonstrates that the incoherent portion of the spectral function has
significant structure in momentum space due to the presence of various energy
scales.Comment: 5 pages, 3 figure
Nonanalytic metric in the presence of gravitomagnetic monopoles
The nonanalytic property of metric resulting from the presence of
gravitomagnetic monopoles is considered. The curvature tensors, dual curvature
tensors, dual Einstein tensor (and hence the gravitational field equation of
gravitomagnetic matter) expressed in terms of nonanalytic metric are analyzed.
It is shown that the spinor gravitomagnetic monopole may be one of the
potential origins of the cosmological constant. An alternative approach to the
cosmological constant problem is thus proposed based on the concept of
gravitomagnetic monopole.Comment: 5 pages, no figures. Keywords: Gravitomagnetic monopole; Nonanalytic
metric; Dual curvature tensors; cosmological constan
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