3,254 research outputs found
Constructing efficient self-organising application layer multicast overlays
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Constructing efficient self-organising application layer multicast overlays
This thesis investigates efficient techniques to build both low cost (i.e. low resource usage) and low delay ALM trees. We focus on self-organising distributed proposals that use limited information about the underlying physical network, limited coordination between the members, and construct overlays with bounded branching degree subject to the bandwidth constraint of each individual member
Spontaneous Subtle Expression Detection and Recognition based on Facial Strain
Optical strain is an extension of optical flow that is capable of quantifying
subtle changes on faces and representing the minute facial motion intensities
at the pixel level. This is computationally essential for the relatively new
field of spontaneous micro-expression, where subtle expressions can be
technically challenging to pinpoint. In this paper, we present a novel method
for detecting and recognizing micro-expressions by utilizing facial optical
strain magnitudes to construct optical strain features and optical strain
weighted features. The two sets of features are then concatenated to form the
resultant feature histogram. Experiments were performed on the CASME II and
SMIC databases. We demonstrate on both databases, the usefulness of optical
strain information and more importantly, that our best approaches are able to
outperform the original baseline results for both detection and recognition
tasks. A comparison of the proposed method with other existing spatio-temporal
feature extraction approaches is also presented.Comment: 21 pages (including references), single column format, accepted to
Signal Processing: Image Communication journa
Echocardiographic parameters versus CHA2DS2-VASc score in prediction of overall cardiac events, heart failure, and stroke in non-valvular atrial fibrillation
Background: Apart from stroke, atrial fibrillation (AF) is associated with higher mortality and heart failure (HF), in which risk stratification scheme is lacking. Therefore this investigation examined the prognostic value of echocardiographic predictors against CHA2DS2-VASc score in permanent non- -valvular AF (NVAF).
Methods: In 252 asymptomatic or mildly symptomatic consecutive patients with NVAF, comprehensive echocardiography was performed. Left atrial deformation parameters were also obtained by two-dimensional speckle tracking echocardiography. End-points pertaining to HF deterioration, ischemic stroke and cardiac death were recorded.
Results: There were 74 cardiovascular events, including 44 deterioration of HF, 22 ischemic strokes and 8 cardiovascular deaths during an average follow-up period of 20.8 ± 13.5 months (interquartile range, 8–31 months). For prediction of overall prognosis and HF, left ventricular mass index, peak early filling velocity (E), and E to tissue Doppler mitral annular early diastolic velocity ratio (E/e’) outperformed CHA2DS2-VASc score in multivariate analysis, area under curve, and stepwise nested regression models. Left ventricular hypertrophy and E/e’ > 8 showed worse overall and heart-failure free survival in Kaplan-Meier curves. For prediction of ischemic stroke, the addition of E or E/e’ to CHA2DS2-VASc score provides extra prognostic value.
Conclusions: Echocardiographic parameters offer incremental value over CHA2DS2-VASc score for prediction of future cardiac events in NVAF. (Cardiol J 2018; 25, 1: 60–71
Light double-gluon hybrid states with the exotic quantum numbers and
We apply the QCD sum rule method to study the double-gluon hybrid states with
the quark-gluon contents () and . We
construct twenty-eight double-gluon hybrid currents, eleven of which are found
to be zero due to some internal symmetries between the two gluons fields. We
concentrate on the non-vanishing currents with the exotic quantum numbers
and . Their masses are calculated to be GeV, GeV, GeV, and GeV. The decay behaviors of the states
are studied, and we propose to search for them in the channels in future particle experiments.Comment: 14 pages, 3 figures, 2 tables, accepted by PR
Numerical investigations on interactions between 2D/3D conical shock wave and axisymmetric boundary layer at Ma=2.2
Numerical simulation and analysis are carried out on interactions between a
2D/3D conical shock wave and an axisymmetric boundary layer with reference to
the experiment by Kussoy et al., in which the shock was generated by a 15-deg
half-angle cone in a tube at 15-deg angle of attack (AOA). Based on the RANS
equations and Menter's SST turbulence model, the present study uses the newly
developed WENO3-PRM211 scheme and the PHengLEI CFD platform for the
computations. First, computations are performed for the 3D interaction
corresponding to the conditions of the experiment by Kussoy et al., and these
are then extended to cases with AOA = 10-deg and 5-deg. For comparison, 2D
axisymmetric counterparts of the 3D interactions are investigated for cones
coaxial with the tube and having half-cone angles of 27.35-deg, 24.81-deg, and
20.96-deg. The shock wave structure, vortex structure, variable distributions,
and wall separation topology of the interaction are computed. The results show
that in 2D/3D interactions, a new Mach reflection-like event occurs and a Mach
stem-like structure is generated above the front of the separation bubble,
which differs from the model of Babinsky for 2D planar shock wave/boundary
layer interaction. A new interaction model is established to describe this
behavior. The relationship between the length of the circumferentially
unseparated region in the tube and the AOA of the cone indicates the existence
of a critical AOA at which the length is zero, and a prediction of this angle
is obtained using an empirical fit, which is verified by computation. The
occurrence of side overflow in the windward meridional plane is analyzed, and a
quantitative knowledge is obtained. To elucidate the characteristics of the 3D
interaction, the scale and structure of the vortex and the pressure and
friction force distributions are presented and compared with those of the 2D
interaction
Effectiveness of RSS feed item duplication detection using word matching
Users of feed aggregators know that duplicated articles are found occasionally on the feeds they subscribe to. It can be time consuming to read all articles and stumble upon duplicated items they have already read. Our work here is to determine the effectiveness of using basic word matching to remove duplicated items and only show the most relevant item, thus saving readers’ time. The method described in this paper to remove duplicates involves word matching heuristics with an appropriate matching percentage. The duplicated feeds are then ranked to only display the highest ranked article. Ranking is done using the number of search items found on the titles of the news feeds where the highest number returned will be considered the highest ranked article. Using Malaysian online news feeds, our method found that with a matching percentage of 40%, our method will be able to minimize duplicates effectively with minimal errors. We did further empirical studies using 9 technology blog feeds over a longer period to provide us with a better averaging results. The matching percentage obtained is also within the same quantum. The method described here has a low overhead in terms of processing for the duplicates and with careful selection of matching percentage, the system will effectively remove the majority of duplicate
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