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An isogeometric approach for nonlocal bending and free oscillation of magneto-electro-elastic functionally graded nanobeam with elastic constraints

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Frontiers of Structural and Civil Engineering 2024年第9期18卷 1401-1423页

作者： Thu Huong NGUYEN THI Van ke TRAN Quoc Hoa PHAM School of Mechanical and Automotive Engineering Hanoi University of IndustryHanoi 100000Vietnam Faculty of Mechanical Engineering Le Quy Don Technical UniversityHanoi 100000Vietnam Faculty of Engineering and Technology Nguyen Tat Thanh UniversityHo Chi Minh City 700000Vietnam

This work uses isogeometric analysis(IGA),which is based on nonlocal hypothesis and higher-order shear beam hypothesis,to investigate the static bending and free oscillation of a magneto-electro-elastic functionally graded(MEE-FG)nanobeam subject to elastic boundary constraints(BCs).The magneto-electric boundary condition and the Maxwell equation are used to calculate the variation of electric and magnetic potentials along the thickness direction of the *** study is innovative since it does not use the conventional boundary ***,an elastic system of straight and torsion springs with controllable stiffness is used to support nanobeams’beginning and end positions,creating customizable *** governing equations of motion of nanobeams are established by applying Hamilton’s principle and IGA is used to determine deflections and natural frequency *** studies were performed to evaluate the convergence and accuracy of the proposed *** from this,the impact of the input parameters on the static bending and free oscillation of the MEE-FG nanobeam is examined in *** findings could be valuable for analyzing and designing innovative structures constructed of functionally graded MEE materials.

关键词： elastic boundary conditions isogeometric analysis nanobeam via nonlocal theory grading of magneto-electro-elastic functions

A hybrid attention model based on first-order statistical features for smoke recognition

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Science China(Technological Sciences) 2024年第3期67卷 809-822页

作者： GUO Nan LIU JiaHui DI keXin GU ke QIAO Junfei Beijing Laboratory of Smart Environmental Protection Beijing Key Laboratory of Computational Intelligence and Intelligent SystemBeijing Artificial Intelligence InstituteBeijing 100124China Faculty of Information Technology Beijing University of TechnologyBeijing 100124China

Smoke and fire recognition are of great importance on foreseeing fire disasters and preventing environmental pollution by monitoring the burning process of objects(e.g., straw, fuels). However, since fire images suffer from problems like the variability of the features, complexity of scenarios, interference from background, changeable weather conditions as well as image quality problems, identifying smoke and fire accurately and promptly from a given image still remains a substantial challenge. Automatically learning the features of smoke images by CNNs has improved the target recognition ability compared to traditional approaches,nonetheless, convolutions and pooling operations in CNNs may cause severe information loss which may lead to *** tackle the above problems, this paper proposed a hybrid attention model based on the characteristics of smoke images. This model adopted multiple optimized attention mechanism in several stages to quickly and precisely capture the important features,achieving state-of-the-art performance on smoke and fire recognition in terms of accuracy and speed. Our proposed module mainly consists of two stages: pooling and attention. In the first stage, we conducted several newly proposed first-order pooling methods. Through traversing the data space in a larger scope, features are better reserved, thus constructing a more intact feature space of smoke and fire in an image. In the second stage, feature maps are aggregated together to perform channel and spatial attention. The channel and spatial dependencies allow us to quickly catch the important features presented in an image. By fully exploring the feature space and prominent salient features, characteristics of smoke and fire are better presented so as to obtain better smoke and fire detection results. Experiments have been conducted on public smoke detection dataset and new proposed fine-grained smoke and fire detection database. Experimental results revealed that the propose

关键词： hybrid attention first-order pooling smoke and fire detection deep convolutional neural networks

Reinforcement Learning-Based Dynamic Order Recommendation for On-Demand Food Delivery

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Tsinghua Science and Technology 2024年第2期29卷 356-367页

作者： Xing Wang Ling Wang Chenxin Dong Hao Ren ke Xing Department of Automation Tsinghua UniversityBeijing 100080China School of Mechanical and Automotive Engineering Qingdao Hengxing University of Science and TechnologyQingdao 266100China Meituan Beijing 100015China

On-demand food delivery(OFD)is gaining more and more popularity in modern *** a kernel order assignment manner in OFD scenario,order recommendation directly influences the delivery efficiency of the platform and the delivery experience of *** paper addresses the dynamism of the order recommendation problem and proposes a reinforcement learning solution *** actor-critic network based on long short term memory(LSTM)unit is designed to deal with the order-grabbing conflict between different ***,three rider sequencing rules are accordingly proposed to match different time steps of the LSTM unit with different *** test the performance of the proposed method,extensive experiments are conducted based on real data from Meituan delivery *** results demonstrate that the proposed reinforcement learning based order recommendation method can significantly increase the number of grabbed orders and reduce the number of order-grabbing conflicts,resulting in better delivery efficiency and experience for the platform and riders.

关键词： on-demand food delivery order recommendation reinforcement learning actor-critic network long short term memory

One-step pore diffusion mechanism of Li^(+) in solid electrolyte interphase for fast-charging lithium-ion battery

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Rare Metals 2024年第7期43卷 3438-3440页

作者： Shan Wang Shu-Yuan Liu Alireza Khataee ke-Zhen Qi College of Pharmacy Dali UniversityDali 671000China Research Laboratory of Advanced Water and Wastewater Treatment Processes Department of Applied ChemistryFaculty of ChemistryUniversity of TabrizTabriz 51666-16471Iran Peoples'Friendship University of Russia(RUDN University) Moscow117198Russian Federation

Li^(+) transport in solid electrolyte interphase is recognized as important factor,which has become a research ***,an one-step pore diffusion mechanism for Li^(+) transport through solid electrolyte interphase was proposed,which was different from previous two-step *** one-step pore diffusion process could effectively eliminate the dynamic limitations of Li^(+) transport in solid electrolyte interphase (SEI) for rapid charging *** work will contribute to the development of rapid charging lithium-ion batteries.

关键词： battery mechanism electrolyte

Highly cycle-stable VOPO_(4)-based cathodes for magnesium ion batteries:Insight into the role of interlayer engineering in batteries performance

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Nano Research 2024年第7期17卷 6127-6138页

作者： Jiahe Zhang Jing Shang Xiaojun Zhang ke Wang Yihe Zhang Engineering Research Center of Ministry of Education for Geological Carbon Storage and Low Carbon Utilization of Resources Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid WastesNational Laboratory of Mineral MaterialsSchool of Materials Science and TechnologyChina University of Geosciences(Beijing)Beijing 100083China

It is the sluggish ion migration kinetics that seriously affects the practical performance of the magnesium ion *** though an electrode material design using rational interlayer engineering method could effectively solve this issue,the optimal interlayer distance remains ***,various VOPO_(4)-based electrodes with expanded interlayer spacing were fabricated and the relationship between interlayer structure and battery performance was *** analysis combined with computations unveils the existence of an optimal interlayer structure,as inadequate expansion failed to fully utilization of the material performance,while excessive expansion degraded the electrode *** them,the electrode with triethylene glycol(TEG)intercalation exhibited optimized performance,maintaining excellent cycling stability(191.3 mAh·g^(−1)after 800 cycles).Density functional theory(DFT)demonstrated the effectiveness and limitations to lowering the migration energy barrier by expanding the interlayer *** addition,systematic mechanism research revealed the Mg^(2+)storage process:The stepwise shuttling of Mg^(2+)along the directions that lie in(001)plane triggers two pairs of redox processes,namely V^(5+)/V^(4+)and V^(4+)/V^(3+).This study,regulation of layer spacing to achieve the best integrated performance of electrodes,could deepen the understanding of interlayer engineering and guide the design of advanced multivalent-ion batteries.

关键词： magnesium ion batteries layered electrodes interlayer engineering energy storage mechanisms high kinetics

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Frontiers of Computer Science 2024年第3期18卷 227-229页

作者： Qianwen GOU Yunwei DONG YuJiao WU Qiao ke School of Computer Science Northwestern Polytechnical UniversityXi’an 710129China School of Mathematics and Statistics Northwestern Polytechnical UniversityXi’an 710129China

1 Introduction Program retrieval aims to enable the flexible retrieval of program snippets based on a natural language query,significantly accelerating software development *** shows that over 60%of developers perform program retrieval daily[1].Recent years have witnessed an increasing interest in deep learning-based program retrieval,which aims to construct embedding representations for program snippets and ***,the distribution of natural languages and programs is inconsistent,resulting in a semantic *** critical challenge is to bridge the semantic gap between the programming language and natural language,and accurately measure their similarity.

关键词： semantic similarity retrieval

Hybrid Dynamic Variables-Dependent Event-Triggered Fuzzy Model Predictive Control

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IEEE/CAA Journal of Automatica Sinica 2024年第3期11卷 723-733页

作者： Xiongbo Wan Chaoling Zhang Fan Wei Chuan-ke Zhang Min Wu IEEE the School of Automation China University of Geosciencesthe Hubei Key Laboratory of Advanced Control and Intelligent Automation for Complex Systemsand the Engineering Research Center of Intelligent Technology for Geo-ExplorationMinistry of EducationWuhan 430074China

This article focuses on dynamic event-triggered mechanism(DETM)-based model predictive control(MPC) for T-S fuzzy systems.A hybrid dynamic variables-dependent DETM is carefully devised,which includes a multiplicative dynamic variable and an additive dynamic *** addressed DETM-based fuzzy MPC issue is described as a “min-max” optimization problem(OP).To facilitate the co-design of the MPC controller and the weighting matrix of the DETM,an auxiliary OP is proposed based on a new Lyapunov function and a new robust positive invariant(RPI) set that contain the membership functions and the hybrid dynamic variables.A dynamic event-triggered fuzzy MPC algorithm is developed accordingly,whose recursive feasibility is analysed by employing the RPI *** the designed controller,the involved fuzzy system is ensured to be asymptotically *** examples show that the new DETM and DETM-based MPC algorithm have the advantages of reducing resource consumption while yielding the anticipated performance.

关键词： Dynamic event-triggered mechanism(DETM) hybrid dynamic variables model predictive control(MPC) robust positive invariant(RPI)set T-S fuzzy systems

Effect of Operation Parameters on the Thermal Characteristics in a Planar Solid Oxide Fuel Cell

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Journal of Thermal Science 2024年第5期33卷 1974-1989页

作者： WANG Mingyuan WANG ke WANG Yongqing CHEN Jiangshuai AN Bo TU Shantung School of Mechanics and Safety Engineering Zhengzhou UniversityZhengzhou 450001China key Laboratory of Process Heat Transfer and Energy Saving of Henan Province Zhengzhou UniversityZhengzhou 450002China School of Mechanical and Power Engineering Zhengzhou UniversityZhengzhou 450001China key Laboratory of Pressure Systems and Safety(MOE) East China University of Science&TechnologyShanghai 200237China

Effective operation strategies in the solid oxide fuel cell(SOFC)can adjust the spatial distribution of temperature gradient favoring the long-term *** investigate the effects of different operating conditions on the thermal behavior inside SOFC,a three-dimensional model is developed in this *** model is verified by comparing it with the experimental *** heat generation rate and its variation under different operating conditions are *** combined effects of operating voltage and gas temperature are considered to be the key factor influencing the temperature *** to the original case,the temperature of SOFC decreases by 21.4 K when the fuel velocity reaches 5 m/*** the maximum temperature gradient increases by21.2%.Meanwhile,higher fuel velocities can eliminate about 32%of the area with higher temperature *** when the oxidant velocity reaches 7.5 m/s,the peak temperature gradient effectively decreases by 16.59%.Simultaneous adjustment of the oxidant and fuel velocities can effectively reduce the peak temperature gradient and increase the safety *** effects of operation conditions on the temperature gradient of the cell are clarified in this study,which can be a reference for further research on the reliability of SOFCs.

关键词： SOFC heat generation temperature gradient distribution heat source thermal behavior

Effects of grain's shape-and size-polydispersities,orientation,and area fraction on tortuosity and permeability of 2D granular media

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Particuology 2024年第7期90卷 535-557页

作者： ke Cao Huisu Chen Mohammad Iqbal Khan Mingqi Li Lin Liu Jiangsu key Laboratory of Construction Materials School of Materials Science and EngineeringSoutheast UniversityNanjing 211189China Department of Civil Engineering College of EngineeringKing Saud UniversityP.O.Box 800Riyadh 11421Saudi Arabia School of Civil and Transportation Engineering Hebei University of TechnologyTianjin 300401China College of Civil and Transportation Engineering Hohai UniversityNanjing210098China

The microstructure of granular media, including grain's shape- and size-polydispersities, orientation, and area fraction can potentially affect its permeability. However, few studies consider the coupling effects of these features. This work employs geometrical probability and stereology to establish quantitative relationships between the above microstructural features and the geometric tortuosity of the two-dimensional granular media containing superellipse, superoval, and polygon grains. Then the lattice Boltzmann method (LBM) is used to determine the permeabilities of these granular media. By combining the tortuosity model and the LBM-derived permeabilities, modified K–C equations are formulated to predict the permeability and the shape factor, considering the grain's shape- and size-polydispersities, orientation, and area fraction. The reliability of these methods can be verified by comparing them with both our simulations and available experimental, theoretical, and numerical data reported in the literature. The findings implicate that the tortuosity and permeability of the granular media are strongly correlated with the grain's shape, orientation, and area fraction but unaffected by the size polydispersity and spatial arrangement of grains. Only circularity is not enough to derive a unified formula for considering the impact of grain shape on tortuosity and permeability, other shape parameters need to be explored in the future.

关键词： Geometric tortuosity Konzey-Carman equation Shape and size ploydispersities Grain orientation Lattice Boltzmann method Granular media