1,061 research outputs found
Assessment of the tradeoff between energy efficiency and transfer opportunities in an urban rail transit network
Urban rail transit (URT) in metropolitan areas consumes huge energy. Energy-efficient timetabling (EET) of URT is an essential measurement of URT management and technologies toward carbon neutralization initiatives. However, the majority EET studies focus on single URT lines ignoring passenger transfer and path choice in the entire URT network. As passenger path choice and timetabling are interdependent in a URT network, the ignorance of passenger transfers potentially results in irrelevant energy efficiency of a URT network. This paper proposes a bi-objective EET model incorporating the minimization of passenger transfer times as an objective in addition to energy efficiency. The timetabling objectives and constraints are linearized, and the bi-objective is transformed into a single objective by a linear weighting method. Utilizing the passenger demand and speed profile data of URT in the City of Xi'an (China), a case study is performed to demonstrate the effectiveness of the proposed EET model. The numerical results show that an optimized timetable solution can reduce 25.1% energy consumption and save 3.3% passenger transfer time.</p
Causal Structure Learning Supervised by Large Language Model
Causal discovery from observational data is pivotal for deciphering complex
relationships. Causal Structure Learning (CSL), which focuses on deriving
causal Directed Acyclic Graphs (DAGs) from data, faces challenges due to vast
DAG spaces and data sparsity. The integration of Large Language Models (LLMs),
recognized for their causal reasoning capabilities, offers a promising
direction to enhance CSL by infusing it with knowledge-based causal inferences.
However, existing approaches utilizing LLMs for CSL have encountered issues,
including unreliable constraints from imperfect LLM inferences and the
computational intensity of full pairwise variable analyses. In response, we
introduce the Iterative LLM Supervised CSL (ILS-CSL) framework. ILS-CSL
innovatively integrates LLM-based causal inference with CSL in an iterative
process, refining the causal DAG using feedback from LLMs. This method not only
utilizes LLM resources more efficiently but also generates more robust and
high-quality structural constraints compared to previous methodologies. Our
comprehensive evaluation across eight real-world datasets demonstrates
ILS-CSL's superior performance, setting a new standard in CSL efficacy and
showcasing its potential to significantly advance the field of causal
discovery. The codes are available at
\url{https://github.com/tyMadara/ILS-CSL}
Back Attention Knowledge Transfer for Low-Resource Named Entity Recognition
In recent years, great success has been achieved in the field of natural
language processing (NLP), thanks in part to the considerable amount of
annotated resources. For named entity recognition (NER), most languages do not
have such an abundance of labeled data as English, so the performances of those
languages are relatively lower. To improve the performance, we propose a
general approach called Back Attention Network (BAN). BAN uses a translation
system to translate other language sentences into English and then applies a
new mechanism named back attention knowledge transfer to obtain task-specific
information from pre-trained high-resource languages NER model. This strategy
can transfer high-layer features of well-trained model and enrich the semantic
representations of the original language. Experiments on three different
language datasets indicate that the proposed approach outperforms other
state-of-the-art methods
Observation of in
Using a sample of events recorded with
the BESIII detector at the symmetric electron positron collider BEPCII, we
report the observation of the decay of the charmonium state
into a pair of mesons in the process
. The branching fraction is measured for the first
time to be , where the first uncertainty is
statistical, the second systematic and the third is from the uncertainty of
. The mass and width of the are
determined as MeV/ and
MeV.Comment: 13 pages, 6 figure
Evidence of a resonant structure in the cross section between 4.05 and 4.60 GeV
The cross section of the process for
center-of-mass energies from 4.05 to 4.60~GeV is measured precisely using data
samples collected with the BESIII detector operating at the BEPCII storage
ring.
Two enhancements are clearly visible in the cross section around 4.23 and
4.40~GeV.
Using several models to describe the dressed cross section yields stable
parameters for the first enhancement, which has a mass of 4228.6 \pm 4.1 \pm
6.3 \un{MeV}/c^2 and a width of 77.0 \pm 6.8 \pm 6.3 \un{MeV}, where the
first uncertainties are statistical and the second ones are systematic.
Our resonant mass is consistent with previous observations of the
state and the theoretical prediction of a molecule.
This result is the first observation of associated with an
open-charm final state.
Fits with three resonance functions with additional , ,
, , or a new resonance, do not show significant
contributions from either of these resonances. The second enhancement is not
from a single known resonance. It could contain contributions from
and other resonances, and a detailed amplitude analysis is required to better
understand this enhancement
Observation and study of the decay
We report the observation and study of the decay
using events
collected with the BESIII detector. Its branching fraction, including all
possible intermediate states, is measured to be
. We also report evidence for a structure,
denoted as , in the mass spectrum in the GeV/
region. Using two decay modes of the meson ( and
), a simultaneous fit to the mass spectra is
performed. Assuming the quantum numbers of the to be , its
significance is found to be 4.4, with a mass and width of MeV/ and MeV, respectively, and a
product branching fraction
. Alternatively, assuming , the
significance is 3.8, with a mass and width of MeV/ and MeV, respectively, and a product
branching fraction
. The angular distribution of
is studied and the two assumptions of the
cannot be clearly distinguished due to the limited statistics. In all
measurements the first uncertainties are statistical and the second systematic.Comment: 10 pages, 6 figures and 4 table
Observation of and confirmation of its large branching fraction
The baryonic decay is observed, and the
corresponding branching fraction is measured to be
, where the first uncertainty is statistical
and second systematic. The data sample used in this analysis was collected with
the BESIII detector operating at the BEPCII double-ring collider with
a center-of-mass energy of 4.178~GeV and an integrated luminosity of
3.19~fb. The result confirms the previous measurement by the CLEO
Collaboration and is of greatly improved precision, which may deepen our
understanding of the dynamical enhancement of the W-annihilation topology in
the charmed meson decays
Challenges in QCD matter physics - The Compressed Baryonic Matter experiment at FAIR
Substantial experimental and theoretical efforts worldwide are devoted to
explore the phase diagram of strongly interacting matter. At LHC and top RHIC
energies, QCD matter is studied at very high temperatures and nearly vanishing
net-baryon densities. There is evidence that a Quark-Gluon-Plasma (QGP) was
created at experiments at RHIC and LHC. The transition from the QGP back to the
hadron gas is found to be a smooth cross over. For larger net-baryon densities
and lower temperatures, it is expected that the QCD phase diagram exhibits a
rich structure, such as a first-order phase transition between hadronic and
partonic matter which terminates in a critical point, or exotic phases like
quarkyonic matter. The discovery of these landmarks would be a breakthrough in
our understanding of the strong interaction and is therefore in the focus of
various high-energy heavy-ion research programs. The Compressed Baryonic Matter
(CBM) experiment at FAIR will play a unique role in the exploration of the QCD
phase diagram in the region of high net-baryon densities, because it is
designed to run at unprecedented interaction rates. High-rate operation is the
key prerequisite for high-precision measurements of multi-differential
observables and of rare diagnostic probes which are sensitive to the dense
phase of the nuclear fireball. The goal of the CBM experiment at SIS100
(sqrt(s_NN) = 2.7 - 4.9 GeV) is to discover fundamental properties of QCD
matter: the phase structure at large baryon-chemical potentials (mu_B > 500
MeV), effects of chiral symmetry, and the equation-of-state at high density as
it is expected to occur in the core of neutron stars. In this article, we
review the motivation for and the physics programme of CBM, including
activities before the start of data taking in 2022, in the context of the
worldwide efforts to explore high-density QCD matter.Comment: 15 pages, 11 figures. Published in European Physical Journal
Search for the decay
We search for radiative decays into a weakly interacting neutral
particle, namely an invisible particle, using the produced through the
process in a data sample of
decays collected by the BESIII detector
at BEPCII. No significant signal is observed. Using a modified frequentist
method, upper limits on the branching fractions are set under different
assumptions of invisible particle masses up to 1.2 . The upper limit corresponding to an invisible particle with zero mass
is 7.0 at the 90\% confidence level
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