488 research outputs found
Constraints on interacting dark energy models from time-delay cosmography with seven lensed quasars
Measurements of time-delay cosmography of lensed quasars can provide an
independent probe to explore the expansion history of the late-time universe.
In this paper, we employ the time-delay cosmography measurements from seven
lenses (here abbreviated as the TD data) to constrain interacting dark energy
(IDE) models. We mainly focus on the scenario of vacuum energy (with )
interacting with cold dark matter, and consider four typical cases of the
interaction form . When the TD data alone is employed, we find that the IDE
models with seem to have an advantage in relieving the
tension between the cosmic microwave background (CMB) and TD data. When
the TD data is added to the CMB+BAO+SN+ data, we find that: (i) the
coupling parameter in all the considered IDE models is positive within
1 range, implying a mild preference for the case of cold dark matter
decaying into dark energy; (ii) all the considered IDE models aggravate the
tension, while the tension could be slightly relieved in the
IDE model with ; (iii) the Akaike information
criteria of the IDE models with are lower than that of
the CDM model, indicating that these IDE models are more preferred by
the current mainstream data. We conclude that the considered IDE models have
their own different advantages when the TD data is employed, and none of them
can achieve good scores in all aspects.Comment: 10 pages, 4 figure
Constraints on the DGP Universe using observational Hubble parameter
AbstractIn this work, we use observations of the Hubble parameter from the differential ages of passively evolving galaxies and the recent detection of the Baryon Acoustic Oscillations (BAO) at z1=0.35 to constrain the Dvali–Gabadadze–Porrati (DGP) Universe. For the case with a curvature term, we set a prior h=0.73±0.03 and the best-fit values suggest a spatially closed Universe. For a flat Universe, we set h free and we get consistent results with other recent analyses
LF-PGVIO: A Visual-Inertial-Odometry Framework for Large Field-of-View Cameras using Points and Geodesic Segments
In this paper, we propose LF-PGVIO, a Visual-Inertial-Odometry (VIO)
framework for large Field-of-View (FoV) cameras with a negative plane using
points and geodesic segments. The purpose of our research is to unleash the
potential of point-line odometry with large-FoV omnidirectional cameras, even
for cameras with negative-plane FoV. To achieve this, we propose an
Omnidirectional Curve Segment Detection (OCSD) method combined with a camera
model which is applicable to images with large distortions, such as panoramic
annular images, fisheye images, and various panoramic images. The geodesic
segment is sliced into multiple straight-line segments based on the radian and
descriptors are extracted and recombined. Descriptor matching establishes the
constraint relationship between 3D line segments in multiple frames. In our VIO
system, line feature residual is also extended to support large-FoV cameras.
Extensive evaluations on public datasets demonstrate the superior accuracy and
robustness of LF-PGVIO compared to state-of-the-art methods. The source code
will be made publicly available at https://github.com/flysoaryun/LF-PGVIO.Comment: Accepted to IEEE Transactions on Intelligent Vehicles (T-IV). The
source code will be made publicly available at
https://github.com/flysoaryun/LF-PGVI
Accumulative time-based ranking method to reputation evaluation in information networks
With the rapid development of modern technology, the Web has become an
important platform for users to make friends and acquire information. However,
since information on the Web is over-abundant, information filtering becomes a
key task for online users to obtain relevant suggestions. As most Websites can
be ranked according to users' rating and preferences, relevance to queries, and
recency, how to extract the most relevant item from the over-abundant
information is always a key topic for researchers in various fields. In this
paper, we adopt tools used to analyze complex networks to evaluate user
reputation and item quality. In our proposed accumulative time-based ranking
(ATR) algorithm, we incorporate two behavioral weighting factors which are
updated when users select or rate items, to reflect the evolution of user
reputation and item quality over time. We showed that our algorithm outperforms
state-of-the-art ranking algorithms in terms of precision and robustness on
empirical datasets from various online retailers and the citation datasets
among research publications
Study on cosmogenic activation in copper for rare event search experiments
The rare event search experiments using germanium detectors are performed in
the underground laboratories to prevent cosmic rays. However, the cosmogenic
activation of the cupreous detector components on the ground will generate long
half-life radioisotopes and contribute continually to the expected background
level. We present a study on the cosmogenic activation of copper after 504 days
of exposure at an altitude of 2469.4 m outside the China Jinping Underground
Laboratory (CJPL). The specific activities of the cosmogenic nuclides produced
in the copper bricks were measured using a low background germanium gamma-ray
spectrometer at CJPL. The production rates at sea level, in units of
nuclei/kg/day, are 18.6 \pm 2.0 for Mn-54, 9.9 \pm 1.3 for Co-56, 48.3 \pm 5.5
for Co-57, 51.8 \pm 2.5 for Co-58 and 39.7 \pm 5.7 for Co-60, respectively.
Given the expected exposure history of the germanium detectors, a Monte Carlo
simulation is conducted to assess the cosmogenic background contributions of
the detectors' cupreous components.Comment: 6 pages, 4 figure
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