38 research outputs found
The dependence of the structure of planet-opened gaps in protoplanetary disks on radiative cooling
Planets can excite density waves and open annular gas gaps in protoplanetary
disks. The depth of gaps is influenced by the evolving angular momentum carried
by density waves. While the impact of radiative cooling on the evolution of
density waves has been studied, a quantitative correlation to connect gap depth
with the cooling timescale is lacking. To address this gap in knowledge, we
employ the grid-based code Athena++ to simulate disk-planet interactions,
treating cooling as a thermal relaxation process. We establish quantitative
dependences of steady-state gap depth (Eq. 36) and width (Eq. 41) on planetary
mass, Shakura-Sunyaev viscosity, disk scale height, and thermal relaxation
timescale . We confirm previous results that gap opening is the
weakest when thermal relaxation timescale is comparable to local dynamical
timescale. Significant variations in gap depth, up to an order of magnitude,
are found with different . In terms of width, a gap is at its narrowest
around , approximately to narrower compared to the
isothermal case. When , it can be wider, and higher
viscosity enhances this effect. We derive possible masses of the gas
gap-opening planets in AS 209, HD 163296, MWC 480, and HL Tau, accounting for
the uncertainties in local thermal relaxation timescale.Comment: 19 pages, 16 figures, 4 tables, accepted for publication in Ap
Atmospheric Recyling of Volatiles by Pebble-Accreting Planets
Planets, embedded in their natal discs, harbour hot envelopes. When pebbles
are accreted by these planets, the contained volatile components may sublimate,
enriching the envelope and potentially changing its thermodynamical properties.
However, the envelopes of embedded planets actively exchange material with the
disc, which would limit the buildup of a vapour-rich atmosphere. To properly
investigate these processes, we have developed a new phase change module to
treat the sublimation process with hydrodynamical simultions. Combined with the
recently developed multi-dust fluid approach, we conduct 2D self-consistent
hydrodynamic simulations to study how pebble sublimation influences the water
content of super-Earths and sub-Neptunes. We find the extent and the amount of
vapour that a planet is able to hold on to is determined by the relative size
of the sublimation front and the atmosphere. When the sublimation front lies
far inside the atmosphere, vapour tends to be locked deep in the atmosphere and
keeps accumulating through a positive feedback mechanism. On the other hand,
when the sublimation front exceeds the (bound) atmosphere, the ice component of
incoming pebbles can be fully recycled and the vapour content reaches a low,
steady value. Low disc temperature, small planet mass and high pebble flux
(omitting accretion heating by pebbles) render the planet atmosphere
vapour-rich while the reverse changes render it vapour-poor. The phase change
module introduced here can in future studies also be employed to model the
chemical composition of the gas in the vicinity of accreting planets and around
snowlines.Comment: 21 pages, 16 figures. Accepted for publication in MNRAS on June 5th
202
Learning to Check Contract Inconsistencies
Contract consistency is important in ensuring the legal validity of the
contract. In many scenarios, a contract is written by filling the blanks in a
precompiled form. Due to carelessness, two blanks that should be filled with
the same (or different)content may be incorrectly filled with different (or
same) content. This will result in the issue of contract inconsistencies, which
may severely impair the legal validity of the contract. Traditional methods to
address this issue mainly rely on manual contract review, which is
labor-intensive and costly. In this work, we formulate a novel Contract
Inconsistency Checking (CIC) problem, and design an end-to-end framework,
called Pair-wise Blank Resolution (PBR), to solve the CIC problem with high
accuracy. Our PBR model contains a novel BlankCoder to address the challenge of
modeling meaningless blanks. BlankCoder adopts a two-stage attention mechanism
that adequately associates a meaningless blank with its relevant descriptions
while avoiding the incorporation of irrelevant context words. Experiments
conducted on real-world datasets show the promising performance of our method
with a balanced accuracy of 94.05% and an F1 score of 90.90% in the CIC
problem.Comment: Accepted by AAAI 202
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Efficient and bright warm-white electroluminescence from lead-free metal halides.
Solution-processed metal-halide perovskites are emerging as one of the most promising materials for displays, lighting and energy generation. Currently, the best-performing perovskite optoelectronic devices are based on lead halides and the lead toxicity severely restricts their practical applications. Moreover, efficient white electroluminescence from broadband-emission metal halides remains a challenge. Here we demonstrate efficient and bright lead-free LEDs based on cesium copper halides enabled by introducing an organic additive (Tween, polyethylene glycol sorbitan monooleate) into the precursor solutions. We find the additive can reduce the trap states, enhancing the photoluminescence quantum efficiency of the metal halide films, and increase the surface potential, facilitating the hole injection and transport in the LEDs. Consequently, we achieve warm-white LEDs reaching an external quantum efficiency of 3.1% and a luminance of 1570 cd m-2 at a low voltage of 5.4 V, showing great promise of lead-free metal halides for solution-processed white LED applications
DeePMD-kit v2: A software package for Deep Potential models
DeePMD-kit is a powerful open-source software package that facilitates
molecular dynamics simulations using machine learning potentials (MLP) known as
Deep Potential (DP) models. This package, which was released in 2017, has been
widely used in the fields of physics, chemistry, biology, and material science
for studying atomistic systems. The current version of DeePMD-kit offers
numerous advanced features such as DeepPot-SE, attention-based and hybrid
descriptors, the ability to fit tensile properties, type embedding, model
deviation, Deep Potential - Range Correction (DPRc), Deep Potential Long Range
(DPLR), GPU support for customized operators, model compression, non-von
Neumann molecular dynamics (NVNMD), and improved usability, including
documentation, compiled binary packages, graphical user interfaces (GUI), and
application programming interfaces (API). This article presents an overview of
the current major version of the DeePMD-kit package, highlighting its features
and technical details. Additionally, the article benchmarks the accuracy and
efficiency of different models and discusses ongoing developments.Comment: 51 pages, 2 figure