140 research outputs found
Communication-Efficient Decentralized Multi-Agent Reinforcement Learning for Cooperative Adaptive Cruise Control
Connected and autonomous vehicles (CAVs) promise next-gen transportation
systems with enhanced safety, energy efficiency, and sustainability. One
typical control strategy for CAVs is the so-called cooperative adaptive cruise
control (CACC) where vehicles drive in platoons and cooperate to achieve safe
and efficient transportation. In this study, we formulate CACC as a multi-agent
reinforcement learning (MARL) problem. Diverging from existing MARL methods
that use centralized training and decentralized execution which require not
only a centralized communication mechanism but also dense inter-agent
communication, we propose a fully-decentralized MARL framework for enhanced
efficiency and scalability. In addition, a quantization-based communication
scheme is proposed to reduce the communication overhead without significantly
degrading the control performance. This is achieved by employing randomized
rounding numbers to quantize each piece of communicated information and only
communicating non-zero components after quantization. Extensive experimentation
in two distinct CACC settings reveals that the proposed MARL framework
consistently achieves superior performance over several contemporary benchmarks
in terms of both communication efficiency and control efficacy.Comment: 11 pages, 7 figure
Explicit gain equations for hybrid graphene-quantum-dot photodetectors
Graphene is an attractive material for broadband photodetection but suffers
from weak light absorption. Coating graphene with quantum dots can
significantly enhance light absorption and create extraordinarily high photo
gain. This high gain is often explained by the classical gain theory which is
unfortunately an implicit function and may even be questionable. In this work,
we managed to derive explicit gain equations for hybrid graphene-quantum-dot
photodetectors. Due to the work function mismatch, lead sulfide (PbS) quantum
dots coated on graphene will form a surface depletion region near the interface
of quantum dots and graphene. Light illumination narrows down the surface
depletion region, creating a photovoltage that gates the graphene. As a result,
high photo gain in graphene is observed. The explicit gain equations are
derived from the theoretical gate transfer characteristics of graphene and the
correlation of the photovoltage with the light illumination intensity. The
derived explicit gain equations fit well with the experimental data, from which
physical parameters are extracted.Comment: 14 pages, 6 figure
Reconstruction of the event vertex in the PandaX-III experiment with convolution neural network
The tracks left by charged particles in a gaseous time projection
chamber~(TPC) incorporate important information about the interaction process
and drift of electrons in gas. The electron diffusion information carried by
the tracks is an effective signature to reconstruct , the vertex position
in drift direction at which the event takes place. In this paper, we propose to
reconstruct with convolution neural network~(CNN) in the PandaX-III
experiment. A CNN model VGGZ0net is built and validated with Monte Carlo
simulation data. It gives with a 11~cm precision for the events above
2~MeV uniformly distributed along a drift distance of 120~cm, and then the
electron lifetime can be deduced. The energy resolution of detector is
significantly improved after the electron lifetime correction, i.e., from
10.1\% to 4.0\% FWHM at the Q-value of double beta decay of Xe for the
scenario with an electron lifetime of 6.5~ms. The CNN model is also
successfully applied to the experimental data of the PandaX-III prototype
detector for reconstruction
Signal identification with Kalman Filter towards background-free neutrinoless double beta decay searches in gaseous detectors
Particle tracks and differential energy loss measured in high pressure
gaseous detectors can be exploited for event identification in neutrinoless
double beta decay~() searches. We develop a new method based
on Kalman Filter in a Bayesian formalism (KFB) to reconstruct meandering tracks
of MeV-scale electrons. With simulation data, we compare the signal and
background discrimination power of the KFB method assuming different detector
granularities and energy resolutions. Typical background from Th and
U decay chains can be suppressed by another order of magnitude than
that in published literatures, approaching the background-free regime. For the
proposed PandaX-III experiment, the search half-life
sensitivity at the 90\% confidence level would reach ~yr
with 5-year live time, a factor of 2.7 improvement over the initial design
target
- …