3,935 research outputs found
First-principles calculations of phase transition, elasticity, and thermodynamic properties for TiZr alloy
tructural transformation, pressure dependent elasticity behaviors, phonon,
and thermodynamic properties of the equiatomic TiZr alloy are investigated by
using first-principles density-functional theory. Our calculated lattice
parameters and equation of state for and phases as well as
the phase transition sequence of
are
consistent well with experiments. Elastic constants of and
phases indicate that they are mechanically stable. For cubic phase,
however, it is mechanically unstable at zero pressure and the critical pressure
for its mechanical stability is predicted to equal to 2.19 GPa. We find that
the moduli, elastic sound velocities, and Debye temperature all increase with
pressure for three phases of TiZr alloy. The relatively large values
illustrate that the TiZr alloy is rather ductile and its ductility is more
predominant than that of element Zr, especially in phase. Elastic wave
velocities and Debye temperature have abrupt increase behaviors upon the
transition at around 10 GPa and exhibit
abrupt decrease feature upon the
transition at higher pressure. Through Mulliken population analysis, we
illustrate that the increase of the \emph{d}-band occupancy will stabilize the
cubic phase. Phonon dispersions for three phases of TiZr alloy are
firstly presented and the phase phonons clearly indicate its
dynamically unstable nature under ambient condition. Thermodynamics of Gibbs
free energy, entropy, and heat capacity are obtained by quasiharmonic
approximation and Debye model.Comment: 9 pages, 10 figure
Privacy-preserving communication and power injection over vehicle networks and 5G smart grid slice
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Self-organization and phase transition in financial markets with multiple choices
Market confidence is essential for successful investing. By incorporating
multi-market into the evolutionary minority game, we investigate the effects of
investor beliefs on the evolution of collective behaviors and asset prices.
When there exists another investment opportunity, market confidence, including
overconfidence and under-confidence, is not always good or bad for investment.
The roles of market confidence is closely related to market impact. For low
market impact, overconfidence in a particular asset makes an investor become
insensitive to losses and a delayed strategy adjustment leads to a decline in
wealth, and thereafter, one's runaway from the market. For high market impact,
under-confidence in a particular asset makes an investor over-sensitive to
losses and one's too frequent strategy adjustment leads to a large fluctuation
in asset prices, and thereafter, a decrease in the number of agents. At an
intermediate market impact, the phase transition occurs. No matter what the
market impact is, an equilibrium between different markets exists, which is
reflected in the occurrence of similar price fluctuations in different markets.
A theoretical analysis indicates that such an equilibrium results from the
coupled effects of strategy updating and shift in investment. The runaway of
the agents trading a specific asset will lead to a decline in the asset price
volatility and such a decline will be inhibited by the clustering of the
strategies. A uniform strategy distribution will lead to a large fluctuation in
asset prices and such a fluctuation will be suppressed by the decrease in the
number of agents in the market. A functional relationship between the price
fluctuations and the numbers of agents is found
A Simple and Effective Self-Supervised Contrastive Learning Framework for Aspect Detection
Unsupervised aspect detection (UAD) aims at automatically extracting
interpretable aspects and identifying aspect-specific segments (such as
sentences) from online reviews. However, recent deep learning-based topic
models, specifically aspect-based autoencoder, suffer from several problems,
such as extracting noisy aspects and poorly mapping aspects discovered by
models to the aspects of interest. To tackle these challenges, in this paper,
we first propose a self-supervised contrastive learning framework and an
attention-based model equipped with a novel smooth self-attention (SSA) module
for the UAD task in order to learn better representations for aspects and
review segments. Secondly, we introduce a high-resolution selective mapping
(HRSMap) method to efficiently assign aspects discovered by the model to
aspects of interest. We also propose using a knowledge distilling technique to
further improve the aspect detection performance. Our methods outperform
several recent unsupervised and weakly supervised approaches on publicly
available benchmark user review datasets. Aspect interpretation results show
that extracted aspects are meaningful, have good coverage, and can be easily
mapped to aspects of interest. Ablation studies and attention weight
visualization also demonstrate the effectiveness of SSA and the knowledge
distilling method
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