65 research outputs found
Alpha-decay half-lives and Q_alpha values of superheavy nuclei
The alpha-decay half-lives of recently synthesized superheavy nuclei (SHN)
are investigated based on a unified fission model (UFM) where a new method to
calculate the assault frequency of alpha-emission is used. The excellent
agreement with the experimental data indicates the UFM is a useful tool to
investigate these alpha-decays. It is found that the half-lives become more and
more insensitive to the Q_alpha values as the atomic number increases on the
whole, which is favorable for us to predict the half-lives of SHN. In addition,
a formula is suggested to compute the Q_alpha values for the nuclei with Z > 92
and N > 140 with a good accuracy, according to which the long-lived SHN should
be neutron rich. With Q_alpha values from this formula as inputs, we predict
the half-lives of isotopes of Z = 117, which may be useful for experimental
identication in the future.Comment: 7 pages, 3 figure
Intertwined charge and pair density orders in a monolayer high-Tc iron-based superconductor
Symmetry-breaking electronic phase in unconventional high-temperature
(high-Tc) superconductors is a fascinating issue in condensed-matter physics,
among which the most attractive phases are charge density wave (CDW) phase with
four unit-cell periodicity in cuprates and nematic phase breaking the C4
rotational symmetry in iron-based superconductors (FeSCs). Recently, pair
density wave (PDW), an exotic superconducting phase with non-zero momentum
Cooper pairs, has been observed in high-Tc cuprates and the monolayer FeSC.
However, the interplay between the CDW, PDW and nematic phase remains to be
explored. Here, using scanning tunneling microscopy/spectroscopy, we detected
commensurate CDW and CDW-induced PDW orders with the same period of lambda =
4aFe (aFe is the distance between neighboring Fe atoms) in a monolayer high-Tc
Fe(Te,Se) film grown on SrTiO3(001) substrate. Further analyses demonstrate the
observed CDW is a smectic order, which breaks both translation and C4
rotational symmetry. Moreover, the smecticity of the CDW order is strongest
near the superconducting gap but weakens near defects and in an applied
magnetic field, indicating the interplay between the smectic CDW and PDW
orders. Our works provide a new platform to study the intertwined orders and
their interactions in high-Tc superconductors
La recherche et la pratique du management interculturel à la centrale nucléaire de Daya Bay
En nous référant à la théorie traditionnelle du management interculturel qui étudie la différence culturelle des nations, nous tenterons de construire un modèle structurant du management interculturel et d’analyser en recourant à ce modèle des actions du management interculturel sur le centrale de Daya Bay. Nous nous proposons par cette recherche de formaliser une nouvelle méthode de management interculturel qui pourrait être une référence pour la construction et le management des futures centrales nucléaires en Chine.Referring to the traditional theory of the intercultural management that studies the cultural difference of the nations, we are tempted to establish a frame model of the intercultural management and resorting to this model analyzer the actions of intercultural management in Daya Bay Station. By this research, we intend to formalize a new model of intercultural management that may be a reference for the construction and management of the futures nuclear power plants in Chine
Hierarchical Pruning of Deep Ensembles with Focal Diversity
Deep neural network ensembles combine the wisdom of multiple deep neural
networks to improve the generalizability and robustness over individual
networks. It has gained increasing popularity to study deep ensemble techniques
in the deep learning community. Some mission-critical applications utilize a
large number of deep neural networks to form deep ensembles to achieve desired
accuracy and resilience, which introduces high time and space costs for
ensemble execution. However, it still remains a critical challenge whether a
small subset of the entire deep ensemble can achieve the same or better
generalizability and how to effectively identify these small deep ensembles for
improving the space and time efficiency of ensemble execution. This paper
presents a novel deep ensemble pruning approach, which can efficiently identify
smaller deep ensembles and provide higher ensemble accuracy than the entire
deep ensemble of a large number of member networks. Our hierarchical ensemble
pruning approach (HQ) leverages three novel ensemble pruning techniques. First,
we show that the focal diversity metrics can accurately capture the
complementary capacity of the member networks of an ensemble, which can guide
ensemble pruning. Second, we design a focal diversity based hierarchical
pruning approach, which will iteratively find high quality deep ensembles with
low cost and high accuracy. Third, we develop a focal diversity consensus
method to integrate multiple focal diversity metrics to refine ensemble pruning
results, where smaller deep ensembles can be effectively identified to offer
high accuracy, high robustness and high efficiency. Evaluated using popular
benchmark datasets, we demonstrate that the proposed hierarchical ensemble
pruning approach can effectively identify high quality deep ensembles with
better generalizability while being more time and space efficient in ensemble
decision making.Comment: To appear on ACM Transactions on Intelligent Systems and Technolog
Rethinking Learning Rate Tuning in the Era of Large Language Models
Large Language Models (LLMs) represent the recent success of deep learning in
achieving remarkable human-like predictive performance. It has become a
mainstream strategy to leverage fine-tuning to adapt LLMs for various
real-world applications due to the prohibitive expenses associated with LLM
training. The learning rate is one of the most important hyperparameters in LLM
fine-tuning with direct impacts on both fine-tuning efficiency and fine-tuned
LLM quality. Existing learning rate policies are primarily designed for
training traditional deep neural networks (DNNs), which may not work well for
LLM fine-tuning. We reassess the research challenges and opportunities of
learning rate tuning in the coming era of Large Language Models. This paper
makes three original contributions. First, we revisit existing learning rate
policies to analyze the critical challenges of learning rate tuning in the era
of LLMs. Second, we present LRBench++ to benchmark learning rate policies and
facilitate learning rate tuning for both traditional DNNs and LLMs. Third, our
experimental analysis with LRBench++ demonstrates the key differences between
LLM fine-tuning and traditional DNN training and validates our analysis
Discovery of a pair density wave state in a monolayer high-Tc iron-based superconductor
The pair density wave (PDW) is an extraordinary superconducting state where
Cooper pairs carry nonzero momentum. It can emerge when the full condensation
of zero momentum Cooper pairs is frustrated. Evidence for the existence of
intrinsic PDW order in high-temperature (high-Tc) cuprate superconductors and
kagome superconductors has emerged recently. However, the PDW order in
iron-based high-Tc superconductors has not been observed experimentally. Here,
using scanning tunneling microscopy/spectroscopy, we report the discovery of
the PDW state in monolayer iron-based high-Tc Fe(Te,Se) films grown on
SrTiO3(001) substrates. The PDW state with a period of {\lambda}~3.6a_Fe (a_Fe
is the distance between neighboring Fe atoms) is observed at the domain walls
by the spatial electronic modulations of the local density of states,
superconducting gap, and the {\pi}-phase shift boundaries of the PDW around the
dislocations of the intertwined charge density wave order. The discovery of the
PDW state in the monolayer Fe(Te,Se) film provides a low-dimensional platform
to study the interplay between the correlated electronic states and
unconventional Cooper pairing in high-Tc superconductors
Invisible Watermarking for Audio Generation Diffusion Models
Diffusion models have gained prominence in the image domain for their
capabilities in data generation and transformation, achieving state-of-the-art
performance in various tasks in both image and audio domains. In the rapidly
evolving field of audio-based machine learning, safeguarding model integrity
and establishing data copyright are of paramount importance. This paper
presents the first watermarking technique applied to audio diffusion models
trained on mel-spectrograms. This offers a novel approach to the aforementioned
challenges. Our model excels not only in benign audio generation, but also
incorporates an invisible watermarking trigger mechanism for model
verification. This watermark trigger serves as a protective layer, enabling the
identification of model ownership and ensuring its integrity. Through extensive
experiments, we demonstrate that invisible watermark triggers can effectively
protect against unauthorized modifications while maintaining high utility in
benign audio generation tasks.Comment: This is an invited paper for IEEE TPS, part of the IEEE CIC/CogMI/TPS
2023 conferenc
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