100 research outputs found
FF2: A Feature Fusion Two-Stream Framework for Punctuation Restoration
To accomplish punctuation restoration, most existing methods focus on
introducing extra information (e.g., part-of-speech) or addressing the class
imbalance problem. Recently, large-scale transformer-based pre-trained language
models (PLMS) have been utilized widely and obtained remarkable success.
However, the PLMS are trained on the large dataset with marks, which may not
fit well with the small dataset without marks, causing the convergence to be
not ideal. In this study, we propose a Feature Fusion two-stream framework
(FF2) to bridge the gap. Specifically, one stream leverages a pre-trained
language model to capture the semantic feature, while another auxiliary module
captures the feature at hand. We also modify the computation of multi-head
attention to encourage communication among heads. Then, two features with
different perspectives are aggregated to fuse information and enhance context
awareness. Without additional data, the experimental results on the popular
benchmark IWSLT demonstrate that FF2 achieves new SOTA performance, which
verifies that our approach is effective.Comment: 5pages. arXiv admin note: substantial text overlap with
arXiv:2203.1248
Ultrasensitive, high-dynamic-range and broadband strain sensing by time-of-flight detection with femtosecond-laser frequency combs
Ultrahigh-resolution optical strain sensors provide powerful tools in various
scientific and engineering fields, ranging from long-baseline interferometers
to civil and aerospace industries. Here we demonstrate an ultrahigh-resolution
fibre strain sensing method by directly detecting the time-of-flight (TOF)
change of the optical pulse train generated from a free-running passively
mode-locked laser (MLL) frequency comb. We achieved a local strain resolution
of 18 p{\epsilon}/Hz1/2 and 1.9 p{\epsilon}/Hz1/2 at 1 Hz and 3 kHz,
respectively, with largedynamic range of >154 dB at 3 kHz. For remote-point
sensing at 1-km distance, 80 p{\epsilon}/Hz1/2 (at 1 Hz) and 2.2
p{\epsilon}/Hz1/2 (at 3 kHz) resolution is demonstrated. While attaining both
ultrahigh resolution and large dynamic range, the demonstrated method can be
readily extended for multiple-point sensing as well by taking advantage of the
broad optical comb spectra. These advantages may allow various applications of
this sensor in geophysical science, structural health monitoring, and
underwater science.Comment: 20 pages, 4 figure
Atmospheric impacts and regulation framework of shipping emissions:achievements, challenges and frontiers
Currently, over 80% of the international trade volume is carried by sea. Marked by persistent growth, evident atmospheric impacts, intricate mitigation challenges, international shipping has been recognized as one of the most “hard-to-abate” sectors gathering increasing attention from both academic community and governmental sectors in recent years. Against the backdrop of the ambitious climate and clean air objectives, the quantitative shipping emission characterization, impact assessment and policy effectiveness research are not only fundamental to understand the status quo and ramifications of shipping emissions but also beneficial for future emission regulations. Here, we summarized the achievements in shipping emission modelling and impact research in the past two decades, and identified the challenges lying in the transition pathway towards a clean and carbon-neutral shipping. To address the pressing demand for this, we proposed an innovative framework which aims to facilitate emission abatement. Finally, promising directions for future work were delineated, including the indirect effects of shipping emitted aerosols on the climate, the emissions and impacts of novel contaminants, synergies and conflicts among different emission reduction measures, projections on future shipping emission inventories, Arctic shipping emissions, etc
Room-temperature continuous-wave pumped exciton polariton condensation in a perovskite microcavity
Microcavity exciton polaritons (polaritons) as part-light part-matter
quasiparticles, garner significant attention for non-equilibrium Bose-Einstein
condensation at elevated temperatures. Recently, halide perovskites have
emerged as promising room-temperature polaritonic platforms thanks to their
large exciton binding energies and superior optical properties. However,
currently, inducing room-temperature non-equilibrium polariton condensation in
perovskite microcavities requires optical pulsed excitations with high
excitation densities. Herein, we demonstrate continuous-wave optically pumped
polariton condensation with an exceptionally low threshold of ~0.6 W cm-2 and a
narrow linewidth of ~1 meV. Polariton condensation is unambiguously
demonstrated by characterizing the nonlinear behavior and coherence properties.
We also identify a microscopic mechanism involving the potential landscape in
the perovskite microcavity, where numerous discretized energy levels arising
from the hybridization of adjacent potential minima enhance the polariton
relaxation, facilitating polariton condensate formation. Our findings lay the
foundation for the next-generation energy-efficient polaritonic devices
operating at room temperature.Comment: 16 pages, 4 figure
Direct mapping of bending and torsional dynamics in individual nanostructures
Investigating coherent acoustic vibrations in nanostructured materials provides fundamental insights into optomechanical responses and microscopic energy flow. Extensive measurements of vibrational dynamics have been performed for a wide variety of nanoparticles and nanoparticle assemblies. However, virtually all of them show that only the dilation modes are launched after laser excitations, and the acoustic bending and torsional motions, which are commonly observed in photoexcited chemical bonds, are absent. Unambiguous identification and refined characterization of these “missing” modes have been a long-standing issue. In this report, we investigated the acoustic vibrational dynamics of individual Au nanoprisms on free-standing graphene substrates using an ultrafast high-sensitivity dark-field imaging approach in four-dimensional transmission electron microscopy. Following optical excitations, we observed low-frequency multiple-mode oscillations and higher superposition amplitudes at nanoprism corners and edges on the subnanoparticle level. In combination with finite-element simulations, we determined that these vibrational modes correspond to out-of-plane bending and torsional motions, superimposed by an overall tilting effect of the nanoprisms. The launch and relaxation processes of these modes are highly pertinent to substrate effects and nanoparticle geometries. These findings contribute to the fundamental understanding about acoustic dynamics of individual nanostructures and their interaction with substrates
- …