14,702 research outputs found
Towards Distributed Convoy Pattern Mining
Mining movement data to reveal interesting behavioral patterns has gained
attention in recent years. One such pattern is the convoy pattern which
consists of at least m objects moving together for at least k consecutive time
instants where m and k are user-defined parameters. Existing algorithms for
detecting convoy patterns, however do not scale to real-life dataset sizes.
Therefore a distributed algorithm for convoy mining is inevitable. In this
paper, we discuss the problem of convoy mining and analyze different data
partitioning strategies to pave the way for a generic distributed convoy
pattern mining algorithm.Comment: SIGSPATIAL'15 November 03-06, 2015, Bellevue, WA, US
Exact solution of a model of qubit dephasing due to telegraph noise
We present a general and exact formalism for finding the evolution of a
quantum system subject to external telegraph noise. The various qubit
decoherence rates are determined by the eigenvalues of a transfer matrix. The
formalism can be applied to a qubit subject to an arbitrary combination of
dephasing and relaxational telegraph noise, in contrast to existing
non-perturbative methods that treat only one or the other of these limits. We
present 3 applications: 1) We obtain the full qubit dynamics on time scales
short compared with the enviromental correlation times. In the strong coupling
cases this reveals unexpected oscillations and induced magnetization
components; 2) We find in strong coupling case strong violations of the widely
used relation 1/T = 1/2T + 1/T, which is a result of
perturbation theory; 3) We discuss the effects of bang-bang and spin-echo
controls of the qubit dynamics in general settings of the telegraph noises.
%The result shows that these methods are not very effective in %reducing
decoherence arising from a single telegraph noise. Finally, we discuss the
extension of the method to the cases of many telegraph noise sources and
multiple qubits. The method still works when white noise is also present.Comment: 7 pages, 6 figures, revised and extende
A conjecture on Hubbard-Stratonovich transformations for the Pruisken-Sch\"afer parameterisations of real hyperbolic domains
Rigorous justification of the Hubbard-Stratonovich transformation for the
Pruisken-Sch\"afer type of parameterisations of real hyperbolic
O(m,n)-invariant domains remains a challenging problem. We show that a naive
choice of the volume element invalidates the transformation, and put forward a
conjecture about the correct form which ensures the desired structure. The
conjecture is supported by complete analytic solution of the problem for groups
O(1,1) and O(2,1), and by a method combining analytical calculations with a
simple numerical evaluation of a two-dimensional integral in the case of the
group O(2,2).Comment: Published versio
Characterization of volatiles Tribolium castaneum (H.) in flour using solid phase microextraction-gas chromatography mass spectrometry (SPME-GCMS)
The objective of this study was to identify volatile organic compounds (VOCs) from flour, Tribolium castaneum (Herbst) and flour infested by T. castaneum separately, to confirm the difference of healthy flour and flour infested by T. castaneum and to explore the new technique to diagnose stored flour's quality by its VOCs change. Headspace-solid phase microextraction (HS-SPME) coupled with gas chromatography (GC) and gas chromatography–mass spectrometry (GC-MS) were used to detect the VOCs of three different samples. Totally, 71 different compounds were identified in flour, T. castaneum and T. castaneum infested flour. Therefore, 27 VOCs were identified from flour alone, 32 VOCs from T. castaneum and 39 VOCs from T. castaneum infested flour. The compound 2-ethyl-2,5-cyclohexadiene-1,4-dione is only found in T. castaneum infested flour. This suggests that 2-ethyl-2,5-cyclohexadiene-1,4-dione can be a useful VOC for detecting T. castaneum in flour
Strong decays of heavy baryons in Bethe-Salpeter formalism
In this paper we study the properties of diquarks (composed of and/or
quarks) in the Bethe-Salpeter formalism under the covariant instantaneous
approximation. We calculate their BS wave functions and study their effective
interaction with the pion. Using the effective coupling constant among the
diquarks and the pion, in the heavy quark limit , we calculate
the decay widths of () in the BS formalism under the
covariant instantaneous approximation and then give predictions of the decay
widths .Comment: 41 pages, 1 figure, LaTex2e, typos correcte
Reference based contrast functions in a semi-blind context
International audienceWe deal with blind signal extraction in the framework of a convolutive mixture of independent sources. Considering so-called reference signals, we generalize former identifiability conditions. Based on this result, we propose to incorporate some a priori information in the references. We show the validity of reference based contrast functions in two semi-blind situations. The results are confirmed by computer simulation
A possible disk mechanism for the 23d QPO in Mkn~501
Optically thin two-temperature accretion flows may be thermally and viscously
stable, but acoustically unstable. Here we propose that the O-mode instability
of a cooling-dominated optically thin two-temperature inner disk may explain
the 23-day quasi-periodic oscillation (QPO) period observed in the TeV and
X-ray light curves of Mkn~501 during its 1997 high state. In our model the
relativistic jet electrons Compton upscatter the disk soft X-ray photons to TeV
energies, so that the instability-driven X-ray periodicity will lead to a
corresponding quasi-periodicity in the TeV light curve and produce correlated
variability. We analyse the dependence of the instability-driven
quasi-periodicity on the mass (M) of the central black hole, the accretion rate
() and the viscous parameter () of the inner disk. We
show that in the case of Mkn~501 the first two parameters are constrained by
various observational results, so that for the instability occurring within a
two-temperature disk where , the quasi-period is expected to
lie within the range of 8 to 100 days, as indeed the case. In particular, for
the observed 23-day QPO period our model implies a viscosity coefficient
, a sub-Eddington accretion rate and a transition radius to the outer standard disk of , and predicts a period variation due to the
motion of the instability region.Comment: 18 pages, 1 figure, accepted by AP
Long-Term Visual Object Tracking Benchmark
We propose a new long video dataset (called Track Long and Prosper - TLP) and
benchmark for single object tracking. The dataset consists of 50 HD videos from
real world scenarios, encompassing a duration of over 400 minutes (676K
frames), making it more than 20 folds larger in average duration per sequence
and more than 8 folds larger in terms of total covered duration, as compared to
existing generic datasets for visual tracking. The proposed dataset paves a way
to suitably assess long term tracking performance and train better deep
learning architectures (avoiding/reducing augmentation, which may not reflect
real world behaviour). We benchmark the dataset on 17 state of the art trackers
and rank them according to tracking accuracy and run time speeds. We further
present thorough qualitative and quantitative evaluation highlighting the
importance of long term aspect of tracking. Our most interesting observations
are (a) existing short sequence benchmarks fail to bring out the inherent
differences in tracking algorithms which widen up while tracking on long
sequences and (b) the accuracy of trackers abruptly drops on challenging long
sequences, suggesting the potential need of research efforts in the direction
of long-term tracking.Comment: ACCV 2018 (Oral
Entangling two distant nanocavities via a waveguide
In this paper, we investigate the generation of continuous variable
entanglement between two spatially-separate nanocavities mediated by a coupled
resonator optical waveguide in photonic crystals. By solving the exact dynamics
of the cavity system coupled to the waveguide, the entanglement and purity of
the two-mode cavity state are discussed in detail for the initially separated
squeezing inputs. It is found that the stable and pure entangled state of the
two distant nanocavities can be achieved with the requirement of only a weak
cavity-waveguide coupling when the cavities are resonant with the band center
of the waveguide. The strong couplings between the cavities and the waveguide
lead to the entanglement sudden death and sudden birth. When the frequencies of
the cavities lie outside the band of the waveguide, the waveguide-induced cross
frequency shift between the cavities can optimize the achievable entanglement.
It is also shown that the entanglement can be easily manipulated through the
changes of the cavity frequencies within the waveguide band.Comment: 8 pages, 8 figure
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