198 research outputs found
Application of Rigorous Interface Boundary Conditions in Mesoscale Plasticity Simulations
The interactions between dislocations and interface/grain boundaries,
including dislocation absorption, transmission, and reflection, have garnered
significant attention from the research community for their impact on the
mechanical properties of materials. However, the traditional approaches used to
simulate grain boundaries lack physical fidelity and are often incompatible
across different simulation methods. We review a new mesoscale interface
boundary condition based on Burgers vector conservation and kinetic dislocation
reaction processes. The main focus of the paper is to demonstrate how to unify
this boundary condition with different plasticity simulation approaches such as
the crystal plasticity finite element, continuum dislocation dynamics, and
discrete dislocation dynamics methods. To validate our interface boundary
condition, we implemented simulations using both the crystal plasticity finite
element method and a two-dimensional continuum dislocation dynamics model. Our
results show that our compact and physically realistic interface boundary
condition can be easily integrated into multiscale simulation methods and yield
novel results consistent with experimental observations.Comment: 19 pages and 7 figure
Machine Learning-Enabled IoT Security: Open Issues and Challenges Under Advanced Persistent Threats
Despite its technological benefits, Internet of Things (IoT) has cyber
weaknesses due to the vulnerabilities in the wireless medium. Machine learning
(ML)-based methods are widely used against cyber threats in IoT networks with
promising performance. Advanced persistent threat (APT) is prominent for
cybercriminals to compromise networks, and it is crucial to long-term and
harmful characteristics. However, it is difficult to apply ML-based approaches
to identify APT attacks to obtain a promising detection performance due to an
extremely small percentage among normal traffic. There are limited surveys to
fully investigate APT attacks in IoT networks due to the lack of public
datasets with all types of APT attacks. It is worth to bridge the
state-of-the-art in network attack detection with APT attack detection in a
comprehensive review article. This survey article reviews the security
challenges in IoT networks and presents the well-known attacks, APT attacks,
and threat models in IoT systems. Meanwhile, signature-based, anomaly-based,
and hybrid intrusion detection systems are summarized for IoT networks. The
article highlights statistical insights regarding frequently applied ML-based
methods against network intrusion alongside the number of attacks types
detected. Finally, open issues and challenges for common network intrusion and
APT attacks are presented for future research.Comment: ACM Computing Surveys, 2022, 35 pages, 10 Figures, 8 Table
ConstGCN: Constrained Transmission-based Graph Convolutional Networks for Document-level Relation Extraction
Document-level relation extraction with graph neural networks faces a
fundamental graph construction gap between training and inference - the golden
graph structure only available during training, which causes that most methods
adopt heuristic or syntactic rules to construct a prior graph as a pseudo
proxy. In this paper, we propose , a novel graph
convolutional network which performs knowledge-based information propagation
between entities along with all specific relation spaces without any prior
graph construction. Specifically, it updates the entity representation by
aggregating information from all other entities along with each relation space,
thus modeling the relation-aware spatial information. To control the
information flow passing through the indeterminate relation spaces, we propose
to constrain the propagation using transmitting scores learned from the Noise
Contrastive Estimation between fact triples. Experimental results show that our
method outperforms the previous state-of-the-art (SOTA) approaches on the DocRE
dataset
Ultra-short-term load prediction of integrated energy system based on load similar fluctuation set classification
Due to the strong coupling characteristics and daily correlation characteristics of multiple load sequences, the prediction method based on time series extrapolation and combined with multiple load meteorological data has limited accuracy improvement, which is tested by the fluctuation of load sequences and the accuracy of Numerical Weather Prediction (NWP). This paper proposes a multiple load prediction method considering the coupling characteristics of multiple loads and the division of load similar fluctuation sets. Firstly, the coupling characteristics of multivariate loads are studied to explore the interaction relationship between multivariate loads and find out the priority of multivariate load prediction. Secondly, the similar fluctuating sets of loads are divided considering the similarity and fluctuation of load sequences. Thirdly, the load scenarios are divided by k-means clustering for the inter-set sequences of similar fluctuating sets, and the Bi-directional Long Short-Term Memory (BI-LSTM) models are trained separately for the sub-set of scenarios and prioritized by prediction. Finally, the effectiveness of the proposed method was verified by combining the multivariate load data provided by the Campus Metabolism system of Arizona State University
Preserving Knowledge Invariance: Rethinking Robustness Evaluation of Open Information Extraction
The robustness to distribution changes ensures that NLP models can be
successfully applied in the realistic world, especially for information
extraction tasks. However, most prior evaluation benchmarks have been devoted
to validating pairwise matching correctness, ignoring the crucial measurement
of robustness. In this paper, we present the first benchmark that simulates the
evaluation of open information extraction models in the real world, where the
syntactic and expressive distributions under the same knowledge meaning may
drift variously. We design and annotate a large-scale testbed in which each
example is a knowledge-invariant clique that consists of sentences with
structured knowledge of the same meaning but with different syntactic and
expressive forms. By further elaborating the robustness metric, a model is
judged to be robust if its performance is consistently accurate on the overall
cliques. We perform experiments on typical models published in the last decade
as well as a popular large language model, the results show that the existing
successful models exhibit a frustrating degradation, with a maximum drop of
23.43 F1 score. Our resources and code are available at
https://github.com/qijimrc/ROBUST.Comment: Accepted by EMNLP 2023 Main Conferenc
Polarization-Insensitive Metasurface for Harvesting Electromagnetic Energy with High Efficiency and Frequency Stability over Wide Range of Incidence Angles
In this paper, a polarization-insensitive metasurface, harvesting electromagnetic (EM) energy with high efficiency and frequency stability over a wide range of incidence angles, is proposed. The previously reported metasurfaces suffer from their maximum efficiencies shifting with the frequency when the incidence angle increases. By introducing a square-shaped metal via ring around the elements, the mutual coupling among adjacent cells is reduced so that the proposed metasurface can maintain maximum efficiency at the fixed operation frequency over a wide range of incidence angles. Furthermore, with one single harvesting via in the proper position for the connection of a harvesting load, the metasurface can collect EM energy effectively with both transverse electric (TE) and transverse magnetic (TM) polarizations in one single harvesting load. Compared with the reported metasurfaces, this proposed metasurface has a higher efficiency and fixed operation frequency within a wide incidence range. The energy distribution, harvesting efficiency, and surface current are simulated to investigate the operation mechanism of the proposed metasurface. The simulation results show that the maximum harvesting efficiency is 91% at 5.8 GHz for both TE and TM polarizations at the normal incidence. When the incident angle increases to 75°, the maximum efficiency is achieved at 5.79 GHz (0.19% shift), and the maximum efficiencies of TM and TE polarizations are 91% and 68%, respectively. A 5 × 5 array is fabricated and tested. The experimental results are in good agreement with the simulated ones
Stress-Induced Epinephrine Enhances Lactate Dehydrogenase A and Promotes Breast Cancer Stem-Like Cells
Chronic stress triggers activation of the sympathetic nervous system and drives malignancy. Using an immunodeficient murine system, we showed that chronic stress–induced epinephrine promoted breast cancer stem-like properties via lactate dehydrogenase A–dependent (LDHA-dependent) metabolic rewiring. Chronic stress–induced epinephrine activated LDHA to generate lactate, and the adjusted pH directed USP28-mediated deubiquitination and stabilization of MYC. The SLUG promoter was then activated by MYC, which promoted development of breast cancer stem-like traits. Using a drug screen that targeted LDHA, we found that a chronic stress–induced cancer stem-like phenotype could be reversed by vitamin C. These findings demonstrated the critical importance of psychological factors in promoting stem-like properties in breast cancer cells. Thus, the LDHA-lowering agent vitamin C can be a potential approach for combating stress-associated breast cancer
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