1,835 research outputs found
PRESS: A Novel Framework of Trajectory Compression in Road Networks
Location data becomes more and more important. In this paper, we focus on the
trajectory data, and propose a new framework, namely PRESS (Paralleled
Road-Network-Based Trajectory Compression), to effectively compress trajectory
data under road network constraints. Different from existing work, PRESS
proposes a novel representation for trajectories to separate the spatial
representation of a trajectory from the temporal representation, and proposes a
Hybrid Spatial Compression (HSC) algorithm and error Bounded Temporal
Compression (BTC) algorithm to compress the spatial and temporal information of
trajectories respectively. PRESS also supports common spatial-temporal queries
without fully decompressing the data. Through an extensive experimental study
on real trajectory dataset, PRESS significantly outperforms existing approaches
in terms of saving storage cost of trajectory data with bounded errors.Comment: 27 pages, 17 figure
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Dehn twists and Lagrangian spherical manifolds
Funder: University of CambridgeAbstract: We study Dehn twists along Lagrangian submanifolds that are finite free quotients of spheres. We describe the induced auto-equivalences to the derived Fukaya category and explain their relations to mirror symmetry
The Radiation Structure of PSR B201628 Observed with FAST
With the largest dish Five-hundred-meter Aperture Spherical radio Telescope
(FAST), both the mean and single pulses of PSR B201628, especially including
the single-pulse structure, are investigated in detail in this study. The mean
pulse profiles at different frequencies can be well fitted in a conal model,
and the peak separation of intensity-dependent pulse profiles increases with
intensity. The integrated pulses are obviously frequency dependent (pulse width
decreases by as frequency increases from 300 MHz to 750 MHz), but
the structure of single pulses changes slightly (the corresponding correlation
scale decreases by only ). This disparity between mean and single
pulses provides independent evidence for the existence of the RS-type vacuum
inner gap, indicating a strong bond between particles on the pulsar surface.
Diffused drifting sub-pulses are analyzed. The results show that the modulation
period along pulse series () is positively correlated to the separation
between two adjacent sub-pulses (). This correlation may hint a rough
surface on the pulsar, eventually resulting in the irregular drift of sparks.
All the observational results may have significant implications in the dynamics
of pulsar magnetosphere and are discussed extensively in this paper.Comment: Sci. China-Phys. Mech. Astron. 62, 959505 (2019
Detection of small single-cycle signals by stochastic resonance using a bistable superconducting quantum interference device
We propose and experimentally demonstrate detecting small single-cycle and
few-cycle signals by using the symmetric double-well potential of a radio
frequency superconducting quantum interference device (rf-SQUID). We show that
the response of this bistable system to single- and few-cycle signals has a
non-monotonic dependence on the noise strength. The response, measured by the
probability of transition from initial potential well to the opposite one,
becomes maximum when the noise-induced transition rate between the two stable
states of the rf-SQUID is comparable to the signal frequency. Comparison to
numerical simulations shows that the phenomenon is a manifestation of
stochastic resonance.Comment: 5 pages 3 figure
An Evolutionary Computation Based Feature Selection Method for Intrusion Detection
Data Availability: The data used to support the fndings of this study are available from the corresponding author upon request. This work was supported by the National Natural Science Foundation of China (61403206, 61771258, and 61876089), the Natural Science Foundation of Jiangsu Province (BK20141005 and BK20160910), the Natural Science Foundation of the Jiangsu Higher Education Institutions of China (14KJB520025), the Priority Academic Program Development of Jiangsu Higher Education Institutions, the Open Research Fund of Jiangsu Engineering Research Center of Communication and Network Technology, NJUPT (JSGCZX17001), and the Natural Science Foundation of Jiangsu Province of China under Grant BK20140883.Peer reviewedPublisher PD
A new framework for the analysis of finite element methods for fluid-structure interaction problems
Finite element methods and kinematically coupled schemes that decouple the
fluid velocity and structure's displacement have been extensively studied for
incompressible fluid-structure interaction (FSI) over the past decade. While
these methods are known to be stable and easy to implement, optimal error
analysis has remained challenging. Previous work has primarily relied on the
classical elliptic projection technique, which is only suitable for parabolic
problems and does not lead to optimal convergence of numerical solutions to the
FSI problems in the standard norm. In this article, we propose a new
kinematically coupled scheme for incompressible FSI thin-structure model and
establish a new framework for the numerical analysis of FSI problems in terms
of a newly introduced coupled non-stationary Ritz projection, which allows us
to prove the optimal-order convergence of the proposed method in the
norm. The methodology presented in this article is also applicable to numerous
other FSI models and serves as a fundamental tool for advancing research in
this field
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