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The optimal strong convergence rates of the truncated EM and logarithmic truncated EM methods for multi-dimensional nonlinear stochastic differential equations

arXiv

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arXiv 2025年

作者： Hu, Xingwei Dai, Xinjie Xiao, Aiguo School of Mathematics and Computational Science Hunan Key Laboratory for Computation and Simulation in Science and Engineering Xiangtan University Hunan Xiangtan411105 China School of Mathematics and Statistics Yunnan University Yunnan Kunming650504 China

The truncated Euler–Maruyama (EM) method, developed by Mao (2015), is used to solve multi-dimensional nonlinear stochastic differential equations (SDEs). However, its convergence rate is suboptimal due to an unnecessary infinitesimal factor. The primary goal of this paper is to demonstrate the optimal convergence of the truncated EM method without infinitesimal factors. Besides, the logarithmic truncated EM method has not been studied in multi-dimensional cases, which is the other goal of this paper. We will show the optimal strong convergence order of the positivity-preserving logarithmic truncated EM method for solving multi-dimensional SDEs with positive solutions. Numerical examples are given to support our theoretical conclusions. Copyright © 2025, The Authors. All rights reserved.

关键词： Stochastic systems

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Deep Learning and Network Analysis:Classifying and Visualizing Geologic Hazard Reports

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Journal of Earth science 2024年第4期35卷 1289-1303页

作者： Wenjia Li Liang Wu Xinde Xu Zhong Xie Qinjun Qiu Hao Liu Zhen Huang Jianguo Chen School of Geography and Information Engineering China University of GeosciencesWuhan430078China Key Laboratory of Geological Survey and Evaluation of Ministry of Education China University of GeosciencesWuhan430078China School of Computer Science China University of GeosciencesWuhan430078China Key Laboratory of Urban Land Resources Monitoring and Simulation Ministry of Natural ResourcesShenzhen518034China Hubei Key Laboratory of Intelligent Vision Based Monitoring for Hydroelectric Engineering China Three Gorges UniversityYichang443002China Wuhan Geomatics Institute Wuhan430074China Faculty of Earth Resources China University of GeosciencesWuhan430074China

If progress is to be made toward improving geohazard management and emergency decision-making,then lessons need to be learned from past geohazard information.A geologic hazard report provides a useful and reliable source of information about the occurrence of an event,along with detailed information about the condition or factors of the *** such reports,however,can be a challenging process because these texts are often presented in unstructured long text formats,and contain rich specialized and detailed *** text classification is commonly used to mine disaster text data in open domains(e.g.,news and microblogs).But it has limitations to performing contextual long-distance dependencies and is insensitive to discourse *** deficiencies are most obviously exposed in long text ***,this paper uses the bidirectional encoder representations from Transformers(BERT),to model long ***,utilizing a softmax layer to automatically extract text features and classify geohazards without manual *** latent Dirichlet allocation(LDA)model is used to examine the interdependencies that exist between causal variables to visualize *** proposed method is useful in enabling the machine-assisted interpretation of text-based ***,it can help users visualize causes,processes,and other geohazards and assist decision-makers in emergency responses.

关键词： geologic hazard network analysis latent dirichlet allocation text classification deep learning

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Synergistic phosphorized NiFeCo and MXene interaction inspired the formation of high-valence metal sites for efficient oxygen evolution

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Journal of Materials science & Technology 2022年第11期106卷 90-97页

作者： Ning Li Jingrui Han Kaili Yao Mei Han Zumin Wang Yongchang Liu Lihua Liu Hongyan Liang School of Materials Science and Engineering Tianjin UniversityTianjin 300350China Key Laboratory of Efficient Utilization of Low and Medium Grade Energy Ministry of EducationTianjin UniversityTianjin 300350China College of Innovation and Entrepreneurship Shanghai Jianqiao UniversityShanghai 201306China State Key Lab of Hydraulic Engineering Simulation and Safety School of Materials Science and EngineeringTianjin UniversityTianjin 300354China

Exploring low-cost,high-performance,and stable electrocatalysts toward the oxygen evolution reaction(OER)is highly desired but remains *** metal hydroxide has been wildly utilized as a promising candidate,but practical implementation is impeded by insufficient catalytic activity,easy agglomeration,and poor ***,we report that both phosphorization and combination with MXnene can improve the catalysts’intrinsic activity and ***,MXene also prevents the agglomeration of the nanoparticles,resulting in the enhanced exposure of active *** char-acterizing and density functional theory simulations revealed that P species can attract electrons to pro-mote the formation of high-valence states of adjacent metal atoms,and coupling MXene support can effectively modulate the electronic structure and optimize the d-band center,which boosts the OER ***,the optimized NiFeCoP/Mxene catalyst exhibits a low overpotential of 240 mV at a current density of 10 mA cm^(−2),a small Tafel slope of 55 mV dec^(−1),and superior long-term stability of 40 h in 1 M KOH electrolyte,which is superior to other counterparts.

关键词： Transition metal phosphide Ti3C2Tx MXene Electrocatalyst Oxygen evolution

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A PRIORI AND A POSTERIORI ERROR ESTIMATES OF A REALLY PRESSURE-ROBUST VIRTUAL ELEMENT METHOD FOR THE INCOMPRESSIBLE BRINKMAN PROBLEM

arXiv

引用

arXiv 2024年

作者： Xiong, Yu Chen, Yanping School of Science Nanjing University of Posts and Telecommunications Nanjing210023 China School of Mathematics and Computational Science Hunan Key Laboratory for Computation and Simulation in Science and Engineering Xiangtan University Hunan Xiangtan411105 China

This paper presents both a priori and a posteriori error analyses for a really pressure-robust virtual element method to approximate the incompressible Brinkman problem. We construct a divergence-preserving reconstruction operator using the Raviart–Thomas element for the discretization on the right-hand side. The optimal priori error estimates are carried out, which imply the velocity error in the energy norm is independent of both the continuous pressure and the viscosity. Taking advantage of the virtual element method’s ability to handle more general polygonal meshes, we implement effective mesh refinement strategies and develop a residual-type a posteriori error estimator. This estimator is proven to provide global upper and local lower bounds for the discretization error. Finally, some numerical experiments demonstrate the robustness, accuracy, reliability and efficiency of the method. Copyright © 2024, The Authors. All rights reserved.

关键词： Mesh generation

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Osteoporotic Vertebral Fracture Classification in X-rays Based on a Multi-modal Semantic Consistency Network

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Journal of Bionic engineering 2022年第6期19卷 1816-1829页

作者： Yuzhao Wang Tian Bai Tong Li Lan Huang College of Computer Science and Technology Jilin UniversityChangchun130012China Key Laboratory of Symbolic Computation and Knowledge Engineering of Ministry of Education Jilin UniversityChangchun130012China Department of Orthopedics The Second Hospital of Jilin UniversityChangchun130012China

Osteoporotic Vertebral Fracture(OVFs)is a common lumbar spine disorder that severely affects the health of *** a clear bone blocks boundary,CT images have gained obvious advantages in OVFs *** with CT images,X-rays are faster and more inexpensive but often leads to misdiagnosis and miss-diagnosis because of the overlapping *** how to transfer CT imaging advantages to achieve OVFs classification in X-rays is *** this purpose,we propose a multi-modal semantic consistency network which could do well X-ray OVFs classification by transferring CT semantic consistency *** from existing methods,we introduce a feature-level mix-up module to get the domain soft labels which helps the network reduce the domain offsets between CT and *** the meanwhile,the network uses a self-rotation pretext task on both CT and X-ray domains to enhance learning the high-level semantic invariant *** employ five evaluation metrics to compare the proposed method with the state-of-the-art *** final results show that our method improves the best value of AUC from 86.32 to 92.16%.The results indicate that multi-modal semantic consistency method could use CT imaging features to improve osteoporotic vertebral fracture classification in X-rays effectively.

关键词： Osteoporotic vertebral fracture classification Cross-modality Unsupervised domain adaptation Transfer learning Convolutional neural network Computer-aided diagnosis

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Design approach of contingency point return trajectory for manned lunar missions based on homotopy continuation 3

Design approach of contingency point return trajectory for m...

引用

2024 3rd International Conference on Aerospace, Aerodynamics and Mechatronics engineering, AAME 2024

作者： Lu, Lin Li, Haiyang Dong, Tianshan Zhu, Binyu College of Aerospace Science and Engineering National University of Defense Technology Changsha410073 China Hunan Key Laboratory of Intelligent Planning and Simulation for Aerospace Missions Changsha410073 China Beijing Institute of Spacecraft System Engineering Beijing100094 China

In terms of the requirement of contingency return during the circumlunar flight phase in manned lunar missions, this article presents a contingency point return trajectory design approach. In consideration of the point return constraint, an initial value estimate model is proposed. A nonlinear programming problem is constructed and solved by adopting an improved differential evolution algorithm with good global search ability. On the basis of the initial value estimate, homotopy continuation is used to gradually approximate and obtain the high-fidelity solution. The simulation results indicate that the design approach can effectively calculate a contingency point return trajectory with good convergence. © Published under licence by IOP Publishing Ltd.

关键词： Lunar missions

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Event-Based Dissipative Path Following Control for Autonomous Ground Vehicles With External Disturbances and Actuator Faults

IEEE Transactions on Intelligent Vehicles

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IEEE Transactions on Intelligent Vehicles 2024年第9期9卷 5728-5738页

作者： Li, Wenfeng Wong, Pak Kin Xie, Zhengchao Gao, Jinwu Hu, Yunfeng Zhao, Jing Northeastern University School of Mechanical Engineering and Automation Shenyang110819 China Northeastern University Foshan Graduate School of Innovation Foshan528311 China University of Macau Department of Electromechanical Engineering 999078 China South China University of Technology Department of Mechanical Engineering Guangzhou510641 China Jilin University State Key Laboratory of Automotive Simulation and Control Department of Control Science and Engineering Changchun130025 China

In this paper, a novel event-based dissipative fuzzy control method is proposed for path following systems of autonomous ground vehicles subject to external disturbances and actuator faults. As the varying longitudinal velocity causes highly nonlinearities in the path following systems, a Takagi-Sugeno fuzzy vehicle dynamics model is established for controller design. Moreover, the time delay, multiple actuator faults and external disturbances are fully considered in the modeling of vehicle dynamic systems. For the improvement of path following performance, a dissipative performance index is employed in the controller design to strengthen the reliability of the control method. To achieve a better economization of the limited resource, an enhanced adaptive event-triggered mechanism is introduced into the controller design. Based on an augmented Lyapunov-Krasovskii functional candidate, a less conservative theorem is obtained by employing some extended integral inequalities. The theorem guarantees that the resulted fuzzy path following control system meets the strict dissipative performance on the premise of asymptotic stability. Finally, experimental results validate the superiority of the proposed method. © 2016 IEEE.

关键词： Linear matrix inequalities

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Generating Redstone Style Cities in Minecraft 5

Generating Redstone Style Cities in Minecraft

引用

5th Annual IEEE Conference on Games, CoG 2023

作者： Huang, Shuo Hu, Chengpeng Togelius, Julian Liu, Jialin Southern University of Science and Technology Guangdong Provincial Key Laboratory of Brain-Inspired Intelligent Computation Department of Computer Science and Engineering Shenzhen518055 China New York University Tandon School of Engineering Department of Computer Science and Engineering New York10012 United States

ISBN: (纸本)9798350322774

Procedurally generating cities in Minecraft provides players more diverse scenarios and could help understand and improve the design of cities in other digital worlds and the real world. This paper presents a city generator that was submitted as an entry to the 2023 Edition of Minecraft Settlement Generation Competition for Minecraft. The generation procedure is composed of six main steps, namely vegetation clearing, terrain reshaping, building layout generation, route planning, streetlight placement, and wall construction. Three algorithms, including a heuristic-based algorithm, an evolving layout algorithm, and a random one are applied to generate the building layout, thus determining where to place different redstone style buildings, and tested by generating cities on random maps in limited time. Experimental results show that the heuristic-based algorithm is capable of finding an acceptable building layout faster for flat maps, while the evolving layout algorithm performs better in evolving layout for rugged maps. A user study is conducted to compare our generator with outstanding entries of the competition's 2022 edition using the competition's evaluation criteria and shows that our generator performs well in the adaptation and functionality criteria. © 2023 IEEE.

关键词： Heuristic algorithms

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Exploring the role of iron in Fe_(5)Ni_(4)S_(8)toward oxygen evolution through modulation of electronic orbital occupancy

引用

Journal of Energy Chemistry 2024年第5期92卷 52-62页

作者： Zhengyan Du Zeshuo Meng Haoteng Sun Yifan Li Chao Jiang Yaxin Li Xiaoying Hu Yi Cui Shansheng Yu Hongwei Tian Key Laboratory of Automobile Materials of MOE School of Materials Science and EngineeringJilin UniversityChangchun 130012JilinChina College of Science and Laboratory of Materials Design and Quantum Simulation Changchun UniversityChangchun 130022JilinChina i-lab Vacuum Interconnected Nanotech Workstation(Nano-X)Suzhou Institute of Nano-Tech and Nano-BionicsChinese Academy of SciencesSuzhou 215123JiangsuChina Department of Chemistry Brown UniversityRI 02912United States

Ni-Fe-based catalysts are considered to be among the most active catalysts for the oxygen evolution reaction(OER)under alkaline conditions,with Fe playing a crucial ***,Fe leaching occurs during the reaction due to thermodynamic instability,which has resulted in conflicting reports within the literature regarding its *** clarify this point,we propose a strategy consisting of modulating the electronic orbital occupancy to suppress the extensive loss of Fe atoms during the OER *** calculations,in-situ X-ray photoelectron spectroscopy,molecular dynamics simulations,and a series of characterization showed that the stable presence of Fe not only accelerates the electron transfer process but also optimizes the reaction barriers of the oxygen evolution intermediates,promoting the phase transition of Fe_(5)Ni_(4)S_(8)to highly active catalytic *** modulated Fe_(5)Ni_(4)S_(8)-based pre-catalysts exhibit improved OER activity and long-term *** study provides a novel perspective for understanding the role of Fe in the OER process.

关键词： Oxygenevolution Fe_(5)Ni_(4)S_(8) Electronic orbital occupancy modulation Reconstruction dynamics

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Uncertainty-Aware Physical simulation of Neural Radiance Fields for Fluids

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Computer Modeling in engineering & sciences 2024年第7期140卷 1143-1163页

作者： Haojie Lian Jiaqi Wang Leilei Chen Shengze Li Ruochen Cao Qingyuan Hu Peiyun Zhao Key Laboratory of In-Situ Property-Improving Mining of Ministry of Education Taiyuan University of TechnologyTaiyuan030024China Henan International Joint Laboratory of Structural Mechanics and Computational Simulation College of Architectural and Civil EngineeringHuanghuai UniversityZhumadian463000China National Innovation Institute of Defense Technology Academy of Military ScienceBeijing100091China School of Software Taiyuan University of TechnologyJinzhong030600China School of Science Jiangnan UniversityWuxi214122China

This paper presents a novel framework aimed at quantifying uncertainties associated with the 3D reconstruction of smoke *** approach reconstructs color and density fields from 2D images using Neural Radiance Field(NeRF)and improves image quality using frequency *** NeRF model is obtained via joint training ofmultiple artificial neural networks,whereby the expectation and standard deviation of density fields and RGB values can be evaluated for each *** addition,customized physics-informed neural network(PINN)with residual blocks and two-layer activation functions are utilized to input the density fields of the NeRF into Navier-Stokes equations and convection-diffusion equations to reconstruct the velocity *** velocity uncertainties are also evaluated through ensemble *** effectiveness of the proposed algorithm is demonstrated through numerical *** presentmethod is an important step towards downstream tasks such as reliability analysis and robust optimization in engineering design.

关键词： Uncertainty quantification neural radiance field physics-informed neural network frequency regularization twolayer activation function ensemble learning

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