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Automatic parsing of sports videos with grammars
Motivated by the analogies between languages and sports videos, we introduce a novel
approach for video parsing with grammars. It utilizes compiler techniques for integrating both semantic
annotation and syntactic analysis to generate a semantic index of events and a table of content for a given
sports video. The video sequence is first segmented and annotated by event detection with domain
knowledge. A grammar-based parser is then used to identify the structure of the video content.
Meanwhile, facilities for error handling are introduced which are particularly useful when the results of
automatic parsing need to be adjusted. As a case study, we have developed a system for video parsing in
the particular domain of TV diving programs. Experimental results indicate the proposed approach is
effectiv
Finite density phase transition of QCD with and using canonical ensemble method
In a progress toward searching for the QCD critical point, we study the
finite density phase transition of and 2 lattice QCD at finite
temperature with the canonical ensemble approach. We develop a winding number
expansion method to accurately project out the particle number from the fermion
determinant which greatly extends the applicable range of baryon number sectors
to make the study feasible. Our lattice simulation was carried out with the
clover fermions and improved gauge action. For a given temperature, we
calculate the baryon chemical potential from the canonical approach to look for
the mixed phase as a signal for the first order phase transition. In the case
of , we observe an "S-shape" structure in the chemical potential-density
plane due to the surface tension of the mixed phase in a finite volume which is
a signal for the first order phase transition. We use the Maxwell construction
to determine the phase boundaries for three temperatures below . The
intersecting point of the two extrapolated boundaries turns out to be at the
expected first order transition point at with . This serves as a
check for our method of identifying the critical point. We also studied the
case, but do not see a signal of the mixed phase for temperature as
low as 0.83 .Comment: 28 pages, 11 figures,references added, final versio
Critical point of QCD from lattice simulations in the canonical ensemble
A canonical ensemble algorithm is employed to study the phase diagram of QCD using lattice simulations. We lock in the desired quark number sector
using an exact Fourier transform of the fermion determinant. We scan the phase
space below and look for an S-shape structure in the chemical potential,
which signals the coexistence phase of a first order phase transition in finite
volume. Applying Maxwell construction, we determine the boundaries of the
coexistence phase at three temperatures and extrapolate them to locate the
critical point. Using an improved gauge action and improved Wilson fermions on
lattices with a spatial extent of 1.8 \fm and quark masses close to that of
the strange, we find the critical point at and baryon
chemical potential .Comment: 5 pages, 7 figures, references added, published versio
Experimental evidence for new symmetry axis of electromagnetic beams
The new symmetry axis of a well-behaved electromagnetic beam advanced in
paper Physical Review A 78, 063831 (2008) is not purely a mathematical concept.
The experimental result reported by Hosten and Kwiat in paper Science 319, 787
(2008) is shown to demonstrate the existence of this symmetry axis that is
neither perpendicular nor parallel to the propagation axis.Comment: 10 pages and 3 figure
Boosted Tidal Disruption by Massive Black Hole Binaries During Galaxy Mergers FROM The View of N-Body Simulation
Supermassive black hole binaries (SMBHBs) are productions of the hierarchical
galaxy formation model. There are many close connections between central SMBH
and its host galaxy because the former plays very important roles on the
formation and evolution of a galaxy. For this reason, the evolution of SMBHBs
in merging galaxies is an essential problem. Since there are many discussions
about SMBHB evolution in gas rich environment, we focus on the quiescent
galaxy, using tidal disruption as a diagnostic tool. Our study is based on a
series of numerical large particle number direct N-body simulations for dry
major mergers. According to the simulation results, the evolution can be
divided into three phases. In phase I, the tidal disruption rate for two well
separated SMBHs in merging system has similar level to single SMBH in isolate
galaxy. After two SMBHs getting close enough to form a bound binary in phase
II, the disruption rate can be enhanced for ~ 2 order of magnitudes within a
short time. This "boosted" disruption stage finishes after the SMBHB evolving
to compact binary system in phase III, corresponding to a drop back of
disruption rate to a level of a few times higher than that in Phase I. How to
correctly extrapolate our N-body simulation results to reality, and
implications of our results to observations, are discussed too.Comment: 16 pages, Accepted for publication in Ap
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