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AHermitian C^(2) Differential Reproducing Kernel Interpolation Meshless Method for the 3D Microstructure-Dependent Static Flexural Analysis of Simply Supported and Functionally Graded Microplates

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Computer Modeling in Engineering & Sciences 2024年第10期141卷 917-949页

作者： Chih-Ping Wu Ruei-Syuan Chang Department of Civil Engineering National Cheng Kung UniversityTainan70101Taiwan

This work develops a Hermitian C^(2) differential reproducing kernel interpolation meshless(DRKIM)method within the consistent couple stress theory(CCST)framework to study the three-dimensional(3D)microstructuredependent static flexural behavior of a functionally graded(FG)microplate subjected to mechanical loads and placed under full simple *** the formulation,we select the transverse stress and displacement components and their first-and second-order derivatives as primary ***,we set up the differential reproducing conditions(DRCs)to obtain the shape functions of the Hermitian C^(2) differential reproducing kernel(DRK)interpolant’s derivatives without using direct *** interpolant’s shape function is combined with a primitive function that possesses Kronecker delta properties and an enrichment function that constituents *** a result,the primary variables and their first-and second-order derivatives satisfy the nodal interpolation ***,incorporating ourHermitianC^(2)DRKinterpolant intothe strong formof the3DCCST,we develop a DRKIM method to analyze the FG microplate’s 3D microstructure-dependent static flexural *** Hermitian C^(2) DRKIM method is confirmed to be accurate and fast in its convergence rate by comparing the solutions it produces with the relevant 3D solutions available in the ***,the impact of essential factors on the transverse stresses,in-plane stresses,displacements,and couple stresses that are induced in the loaded microplate is *** factors include the length-to-thickness ratio,the material length-scale parameter,and the inhomogeneity index,which appear to be significant.

关键词： Consistent/modified couple stress theory differential reproducing kernel methods microplates point collocation methods static flexural 3D microstructure-dependent analysis

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Validity of fatty liver prediction scores for diagnosis of fatty liver by Fibroscan

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Hepatobiliary & Pancreatic Diseases International 2024年第4期23卷 353-360页

作者： Seogsong Jeong Sun Jae Park Seong Kyun Na Sang Min Park Byung-Cheol Song Yun Hwan Oh Department of Biomedical Sciences Seoul National University Graduate SchoolSeoul 03080Korea Department of Biomedical Informatics CHA University School of MedicineCHA UniversitySeongnam 13488Korea Department of Internal Medicine Inje University College of MedicineSeoul 50834Korea Department of Family Medicine Seoul National University HospitalSeoul National University College of MedicineSeoul 03080Korea Department of Internal Medicine Jeju National University HospitalJeju National University College of MedicineJeju 63241Korea Department of Family Medicine Jeju National University HospitalJeju National University College of MedicineJeju 63241Korea Department of Family Medicine Chung-Ang University Gwangmyeong HospitalChung-Ang University College of MedicineGwangmyeong 14353Korea

Background:The Korea national Health and Nutrition Examination Survey nonalcoholic fatty liver disease(K-NAFLD)score was recently developed with the intent to operationally define nonalcoholic fatty liver disease(NAFLD).However,there remained an external validation that confirmed its diagnostic performance,especially in patients with alcohol consumption or hepatitis virus ***:Diagnostic accuracy of the K-NAFLD score was evaluated in a hospital-based cohort consisting of 1388 participants who received Fibroscan®.Multivariate-adjusted logistic regression models and the contrast estimation of receiver operating characteristic curves were used for validation of the K-NAFLD score,fatty liver index(FLI),and hepatic steatosis index(HSI).Results:K-NAFLD-moderate[adjusted odds ratio(aOR)=2.53,95%confidence interval(CI):1.13-5.65]and K-NAFLD-high(aOR=4.14,95%CI:1.69-10.13)groups showed higher risks of fatty liver compared to the K-NAFLD-low group after adjustments for demographic and clinical characteristics,and FLI-moderate and FLI-high groups revealed aORs of 2.05(95%CI:1.22-3.43)and 1.51(95%CI:0.78-2.90),*** addition,the HSI was less predictive for Fibroscan®-defined fatty *** K-NAFLD and FLI also demonstrated high accuracy in the prediction of fatty liver in patients with alcohol consumption and chronic hepatitis virus infection,and the adjusted area under curve values were comparable between K-NAFLD and ***:Externally validation of the K-NAFLD and FLI showed that these scores may be a useful,noninvasive,and non-imaging modality for the identification of fatty *** addition,these scores also predicted fatty liver in patients with alcohol consumption and chronic hepatitis virus infection.

关键词： Nonalcoholic fatty liver disease Fatty liver index Hepatic steatosis index

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N, P co-doped 3D porous carbon with self-assembled morphological control via template-free method for potassiumion battery anodes

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Rare Metals 2024年第9期43卷 4243-4252页

作者： Jeehoon Yu Dae Kyom Kim Hong Geun Oh Seung-Keun Park Youngjae Yoo Department of Advanced Materials Engineering Chung-Ang University

The larger ionic radius of potassium ions than that of lithium ions significantly limits the accomplishment of rapid diffusion kinetics in graphite electrodes for potassium-ion batteries （PIBs）,resulting in comparatively poor rate performance and cycle ***,we report a high-rate performance and cycling stability amorphous carbon electrode achieved through nitrogen and phosphorous *** as-prepared N,P co-doped carbon electrodes have distinct 3D structures with large surface areas,hierarchical pore architectures,and increased interlayer spaces resulting from the direct pyrolysis of supramolecular self-assembled aggregates without *** obtained electrode N3P1 exhibits a reversible specific capacity of 258 m Ah·g-1at a current density of 0.1A·g-1and a good long-term cycle performance (96.1%capacity retention after 800 cycles at 0.5 A·g-1).Kinetic investigations show that the N3P1 electrode with the welldeveloped porous structure and large number of surface defects exhibits capacitive-driven behavior at all scan rates,which may be attributed by N and P ***-situ transmission electron microscopy analyses in the fully discharged and charged states demonstrate structural stability and reversibility owing to the expanded interlayer *** suggested synthesis approach is simple and effective for producing heteroatom-doped carbon materials for PIBs and other advanced electrochemical energy storage materials.

关键词： 3D porous structures Amorphous carbons Nitrogen and phosphorous co-doping Potassium-ion batteries

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Granger causal representation learning for groups of time series

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Science China(Information Sciences) 2024年第5期67卷 56-68页

作者： Ruichu CAI Yunjin WU Xiaokai HUANG Wei CHEN Tom Z.J.FU Zhifeng HAO School of Computer Science Guangdong University of Technology Peng cheng Laboratory College of Science Shantou University

Discovering causality from multivariate time series is an important but challenging *** existing methods focus on estimating the Granger causal structures among multivariate time series,while ignoring the prior knowledge of these time series, e.g., the group of the time series. Focusing on discovering the Granger causal structures among groups of time series, we propose a Granger causal representation learning method to solve this problem. First, we use the multiset canonical correlation analysis method to learn the Granger causal representation of each group of time series. Then, we model the Granger causal relationships among the learned Granger causal representations using a recurrent neural network with temporal information. Finally, we formulate the above two stages into one unified optimization problem, which is efficiently solved using the augmented Lagrangian method. We conduct extensive experiments on synthetic and real-world datasets to validate the correctness and effectiveness of the proposed method.

关键词： Granger causal discovery Granger causal representation learning time series data recurrent neural network multiset canonical correlation analysis

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Understanding adversarial attacks on observations in deep reinforcement learning

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Science China(Information Sciences) 2024年第5期67卷 69-83页

作者： You QIAOBEN chengyang YING Xinning ZHOU Hang SU Jun ZHU Bo ZHANG Department of Computer Science and Technology Beijing National Research Center for Information Science and Technology Tsinghua-Bosch Joint Center for Machine Learning Institute for Artificial Intelligence Tsinghua University Peng cheng Laboratory

Deep reinforcement learning models are vulnerable to adversarial attacks that can decrease the cumulative expected reward of a victim by manipulating its observations. Despite the efficiency of previous optimization-based methods for generating adversarial noise in supervised learning, such methods might not achieve the lowest cumulative reward since they do not generally explore the environmental ***, a framework is provided to better understand the existing methods by reformulating the problem of adversarial attacks on reinforcement learning in the function space. The reformulation approach adopted herein generates an optimal adversary in the function space of targeted attacks, repelling them via a generic two-stage framework. In the first stage, a deceptive policy is trained by hacking the environment and discovering a set of trajectories routing to the lowest reward or the worst-case performance. Next, the adversary misleads the victim to imitate the deceptive policy by perturbing the observations. Compared to existing approaches, it is theoretically shown that our adversary is strong under an appropriate noise level. Extensive experiments demonstrate the superiority of the proposed method in terms of efficiency and effectiveness, achieving state-of-the-art performance in both Atari and MuJoCo environments.

关键词： deep learning reinforcement learning adversarial robustness adversarial attack

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Progenitor-age dependence of type Ia supernova luminosity and its cosmological implication

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Science China(Physics,Mechanics & Astronomy) 2024年第1期67卷 180-181页

作者： Yanhong Yao Yang Wang Haitao Miao School of Physics and Astronomy Sun Yat-sen UniversityZhuhai 519082China Peng cheng Laboratory Shenzhen 518000China national Astronomical Observatories Chinese Academy of SciencesBeijing 100101China

Empirically standardised peak luminosity of Type Ia supernovae(SNe Ia)as a standard candle has become one of the most powerful probes of the expansion history of the late *** the existence of such a consistent peak luminosity could be interpreted as a consequence of the fixed critical Chandrasekhar mass at which a carbon-oxygen white dwarf explodes,there is growing evidence for a more complex environmental dependence to the SN Ia luminosity beyond the current understanding of the SN Ia physics.

关键词： luminosity supernova consequence

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Reconfigurable transmissive metasurface with a combination of scissor and rotation actuators for independently controlling beam scanning and polarization conversion

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Microsystems & Nanoengineering 2024年第2期10卷 173-180页

作者： Chhunheng Lor Ratanak Phon Sungjoon Lim Intelligent Semiconductor Engineering Chung-Ang UniversityHeukseok-DongDongjak-GuSeoul06974Republic of Korea School of Electrical and Electronic Engineering Chung-Ang UniversityHeukseok-DongDongjak-GuSeoul06974Republic of Korea

Polarization conversion and beam scanning metasurfaces are commonly used to reduce polarization mismatch and direct electromagnetic waves in a specific direction to improve the strength of a wireless ***,identifying suitable active and mechanically reconfigurable metasurfaces for polarization conversion and beam scanning is a considerable challenge,and the reported metasurfaces have narrow scanning ranges,are expensive,and cannot be independently *** this paper,we propose a reconfigurable transmissive metasurface combined with a scissor and rotation actuator for independently controlling beam scanning and polarization conversion *** metasurface is constructed with rotatable unit cells(UCs)that can switch the polarization state between right-handed(RHCP)and left-handed circular polarization(LHCP)by flipping the UCs to reverse their phase ***,independent beam scanning is achieved using the scissor actuator to linearly change the distance between the *** and experimental results confirm that the proposed metasurface can perform beam scanning in the range of 28°for both the positive and negative regions of a radiation pattern(RHCP and LHCP beams)at an operational frequency of 10.5 GHz.

关键词： beam rotation controlling

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A Dual Closed-Loop Digital Twin Construction Method for Optimizing the Copper Disc Casting Process

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IEEE/CAA Journal of Automatica Sinica 2024年第3期11卷 581-594页

作者： Zhaohui Jiang Chuan Xu Jinshi Liu Weichao Luo Zhiwen Chen Weihua Gui IEEE the School of Automation Central South UniversityChangsha 410083China the Peng cheng Laboratory Shenzhen 518000China

The copper disc casting machine is core equipment for producing copper anode plates in the copper metallurgy *** copper disc casting machine casting package motion curve(CPMC) is significant for precise casting and efficient ***,the lack of exact casting modeling and real-time simulation information severely restricts dynamic CPMC *** this end,a liquid copper droplet model describes the casting package copper flow pattern in the casting ***,a CPMC optimization model is proposed for the first *** top of this,a digital twin dual closed-loop self-optimization application framework(DT-DCS) is constructed for optimizing the copper disc casting process to achieve self-optimization of the CPMC and closed-loop feedback of manufacturing information during the casting ***,a case study is carried out based on the proposed methods in the industrial field.

关键词： Copper disc casting machine digital twin(DT) mechanism modeling self-optimization

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Macroscopic model and statistical model to characterize electromagnetic information of a digital coding metasurface

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national Science Review 2024年第3期11卷 159-171页

作者： Rui Wen Shao Jun Wei Wu Zheng Xing Wang Hui Xu Han Qing Yang Qiang cheng Tie Jun Cui Institute of Electromagnetic Space Southeast University State Key Laboratory of Millimeter Waves Southeast University Peng cheng Laboratory Pazhou Laboratory(Huangpu)

A digital coding metasurface is a platform connecting the digital space and electromagnetic wave space, and has therefore gained much attention due to its intriguing value in reshaping wireless channels and realizing new communication architectures. Correspondingly, there is an urgent need for electromagnetic information theory that reveals the upper limit of communication capacity and supports the accurate design of metasurface-based communication systems. To this end, we propose a macroscopic model and a statistical model of the digital coding metasurface. The macroscopic model uniformly accommodates both digital and electromagnetic aspects of the meta-atoms and predicts all possible scattered fields of the digital coding metasurface based on a small number of simulations or measurements. Full-wave simulations and experimental results show that the macroscopic model is feasible and accurate. A statistical model is further proposed to correlate the mutual coupling between meta-atoms with covariance and to calculate the entropy of the equivalent currents of digital coding metasurface. These two models can help reconfigurable intelligent surfaces achieve more accurate beamforming and channel estimation, and thus improve signal power and coverage. Moreover, the models will encourage the creation of a precoding codebook in metasurface-based direct digital modulation systems, with the aim of approaching the upper limit of channel capacity. With these two models, the concepts of current space and current entropy, as well as the analysis of information loss from the coding space to wave space, is established for the first time, helping to bridge the gap between the digital world and the physical world, and advancing developments of electromagnetic information theory and new-architecture wireless systems.

关键词： electromagnetic information theory current entropy current space digital coding metasurface macroscopic model statistical model

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Novel N-doped multichannel carbon nanofiber architecture with porous CoS nanoprisms for high-performance potassium-ion batteries

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Rare Metals 2024年第3期43卷 971-983页

作者： Jae Bong Lim Seung-Keun Park Department of Advanced Materials Engineering Chung-Ang UniversityGyeonggi-do17546Republic of Korea Department of Intelligence Energy and Industry Chung-Ang UniversitySeoul06974Republic of Korea Western Seoul Center Korea Basic Science InstituteSeoul03759Republic of Korea

Potassium-ion batteries(PIBs)have gained significant attention as an alternative to lithium-ion batteries(LIBs)due to the abundance of potassium(K)and low ***,the difficulty in finding appropriate electrode materials that can efficiently store the larger K ions has hindered their practical ***,we report a novel anode material,N-doped multichannel carbon nanofibers embedded with porous CoS nanoprisms(CSP@NMCNF),for high-performance *** CSP@NMCNF was synthesized using a two-step strategy comprising of the electrospinning of Co acetate hydroxide nanoprism/binary polymer blend and a subsequent heat *** porous CoS nanoprisms with an anisotropic morphology were well aligned along the length axis of the N-doped multichannel carbon nanofibers,thus ensuring their structural stability during the repeated charge-discharge *** addition,numerous pores facilitated the transport of electrons and ***,the CSP@NMCNF anode exhibited excellent electrochemical performance,delivering a high specific capacity of 368 mAh·g^(-1)at 0.5 A·g^(-1)after 200 cycles and excellent rate capability(232 mAh·g^(-1)at 2.0 A·g^(-1)).

关键词： K-ion batteries Cobalt sulfide Multichannel structured composite Electrospinning Nanoprism Porous structure

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