2,778 research outputs found
SURGE: Continuous Detection of Bursty Regions Over a Stream of Spatial Objects
With the proliferation of mobile devices and location-based services,
continuous generation of massive volume of streaming spatial objects (i.e.,
geo-tagged data) opens up new opportunities to address real-world problems by
analyzing them. In this paper, we present a novel continuous bursty region
detection problem that aims to continuously detect a bursty region of a given
size in a specified geographical area from a stream of spatial objects.
Specifically, a bursty region shows maximum spike in the number of spatial
objects in a given time window. The problem is useful in addressing several
real-world challenges such as surge pricing problem in online transportation
and disease outbreak detection. To solve the problem, we propose an exact
solution and two approximate solutions, and the approximation ratio is
in terms of the burst score, where is a parameter
to control the burst score. We further extend these solutions to support
detection of top- bursty regions. Extensive experiments with real-world data
are conducted to demonstrate the efficiency and effectiveness of our solutions
Kondo Metal and Ferrimagnetic Insulator on the Triangular Kagom\'e Lattice
We obtain the rich phase diagrams in the Hubbard model on the triangular
Kagom\'e lattice as a function of interaction, temperature and asymmetry, by
combining the cellular dynamical mean-field theory with the continuous time
quantum Monte Carlo method. The phase diagrams show the asymmetry separates the
critical points in Mott transition of two sublattices on the triangular
Kagom\'e lattice and produces two novel phases called plaquette insulator with
an obvious gap and a gapless Kondo metal. When the Coulomb interaction is
stronger than the critical value Uc, a short range paramagnetic insulating
phase, which is a candidate for the short rang resonating valence-bond spin
liquid, emerges before the ferrimagnetic order is formed independent of
asymmetry. Furthermore, we discuss how to measure these phases in future
experiments
Anisotropic Rabi model
We define the anisotropic Rabi model as the generalization of the spin-boson
Rabi model: The Hamiltonian system breaks the parity symmetry; the rotating and
counter-rotating interactions are governed by two different coupling constants;
a further parameter introduces a phase factor in the counter-rotating terms.
The exact energy spectrum and eigenstates of the generalized model is worked
out. The solution is obtained as an elaboration of a recent proposed method for
the isotropic limit of the model. In this way, we provide a long sought
solution of a cascade of models with immediate relevance in different physical
fields, including i) quantum optics: two-level atom in single mode cross
electric and magnetic fields; ii) solid state physics: electrons in
semiconductors with Rashba and Dresselhaus spin-orbit coupling; iii) mesoscopic
physics: Josephson junctions flux-qubit quantum circuits.Comment: 5 pages+ 6 pages supplementary, 7 figures, accepted by Phys. Rev.
- …