检索结果-内蒙古大学图书馆

Fast θ -Maruyama scheme for stochastic Volterra integral equations of convolution type: mean-square stability and strong convergence analysis

引用

computational and Applied Mathematics 2023年第3期42卷

作者： Wang, Mengjie Dai, Xinjie Yu, Yanyan Xiao, Aiguo Hunan Key Laboratory for Computation and Simulation in Science and Engineering National Center for Applied Mathematics in Hunan Key Laboratory of Intelligent Computing and Information Processing of Ministry of Education Xiangtan University Hunan Xiangtan411105 China School of Mathematics and Statistics Yunnan University Yunnan Kunming650504 China

In this paper, a fast θ-Maruyama method is proposed for solving stochastic Volterra integral equations of convolution type with singular and Hölder continuous kernels based on the sum-of-exponentials approximation. Furthermore, the average storage O(N) and the calculation cost O(N2) of θ-Maruyama scheme are reduced to O(log N) and O(Nlog N) for T 1 or O(log 2N) and O(Nlog 2N) for T≈ 1 , respectively, which implies that the fast θ-Maruyama scheme is confirmed to improve the computational efficiency of the θ-Maruyama method. Under the local Lipschitz and linear growth conditions, strong convergence of the given numerical scheme are obtained. Then, for the linear test equation, we show the asymptotic behavior of solutions in mean square sense. Further, we obtain the explicit structure of the stability matrices and some numerical results of the mean-square stability for the fast θ-Maruyama method applied to the linear test equation. Finally, some numerical experiments are also given to illustrate the effectiveness of the method. © 2023, The Author(s) under exclusive licence to Sociedade Brasileira de Matemática Aplicada e Computacional.

关键词： computational efficiency

来源：评论

学校读者我要写书评

暂无评论

3D Face Alignment and Face Reconstruction Based on Image Sequence 14

3D Face Alignment and Face Reconstruction Based on Image Seq...

引用

14th International Conference on Digital Image Processing, ICDIP 2022

作者： Wei, Yao Qiao, Biao Wang, Huabin Zhang, Mengxin Liu, Shijun Tao, Liang Anhui Provincial Key Laboratory of Multimodal Cognitive Computation School of Computer Science and Technology Anhui University Hefei China School of Computer Science and Information Engineering Bengbu University Bengbu China

ISBN: (纸本)9781510657564

Existing 3D face alignment and face reconstruction methods mainly focus on the accuracy of the model. When the existing methods are applied to dynamic videos, the stability and accuracy are significantly reduced. To overcome this problem, we propose a novel regression framework that strikes a balance between accuracy and stability. First, on the basis of lightweight backbone, encoder-decoder structure is used to jointly learn expression details and detailed 3D face from video images to recover shape details and their relationship to facial expression, and dynamic regression of a small number of 3D face parameters, effectively improve the speed and accuracy. Secondly, in order to further improve the stability of face landmarks in video, a jitter loss function of multi-frame image joint learning is proposed to strengthen the correlation between frames and face landmarks in video, and reduce the difference amplitude of face landmarks between adjacent frames to reduce the jitter of face landmarks. Experiments on several challenging datasets verify the effectiveness of our method. © 2022 SPIE.

关键词： Jitter

来源：评论

学校读者我要写书评

暂无评论

HIGH ACCURACY TECHNIQUES BASED ADAPTIVE FINITE ELEMENT METHODS FOR ELLIPTIC PDES

arXiv

引用

arXiv 2025年

作者： Xiao, Jingjing Liu, Ying Yi, Nianyu School of Mathematics Shandong University Jinan250100 China School of Science Xi’an University of Technology Xi’an710048 China School of Mathematics and Computational Science Xiangtan University Hunan National Center for Applied Mathematics Hunan Key Laboratory for Computation and Simulation in Science and Engineering Xiangtan411105 China

This paper aims to develop an efficient adaptive finite element method for the second-order elliptic problem. Although the theory for adaptive finite element methods based on residual-type a posteriori error estimator and bisection refinement has been well established, in practical computations, the use of non-asymptotic exact of error estimator and the excessive number of adaptive iteration steps often lead to inefficiency of the adaptive algorithm. We propose an efficient adaptive finite element method based on high-accuracy techniques including the superconvergence recovery technique and high-quality mesh optimization. The centroidal Voronoi Delaunay triangulation mesh optimization is embedded in the mesh adaption to provide high-quality mesh, and then assure that the superconvergence property of the recovered gradient and the asymptotical exactness of the error estimator. A tailored adaptive strategy, which could generate high-quality meshes with a target number of vertices, is developed to ensure the adaptive computation process terminated within 7 steps. The effectiveness and robustness of the adaptive algorithm is numerically demonstrated. Copyright © 2025, The Authors. All rights reserved.

关键词： Triangulation

来源：评论

学校读者我要写书评

暂无评论

Uplink Control Information Based Clustered Access and Discontinuous Reception Management for mMTC

引用

IEEE Communications Letters 2025年第6期29卷 1380-1384页

作者： Wang, Shao-Di Wang, Chang-Long Wang, Hui-Ming Zhou, Feng Leung, Victor C. M. Xidian University Key Laboratory of Electronic Information Countermeasure and Simulation Technology of Ministry of Education Xi’an710071 China Xi’an Jiaotong University School of Information and Communication Engineering Ministry of Education Key Lab for Intelligent Networks and Network Security Xi’an710049 China Shenzhen MSU BIT University Artificial Intelligence Research Institute Shenzhen518172 China Shenzhen University College of Computer Science and Software Engineering Shenzhen518060 China The University of British Columbia Department of Electrical and Computer Engineering VancouverBCV6T 1Z4 Canada

Uplink control information (UCI) and discontinuous reception (DRX) play important roles for massive machine type communication (mMTC). Despite their standalone significance, a conspicuous gap exists in comprehensively exploring the synergy between UCI and DRX concerning both energy conservation and latency reduction for mMTC. In this letter, we propose a UCI-based clustered access and DRX management (UCADM) scheme that strikes a balance between these two critical performance metrics, reducing energy usage while preserving low latency in uplink-downlink interaction for mMTC. Specifically, we present a strictly feasible solution for the proposed UCADM scheme by using the spectral radius and the constraint projection, which can effectively solve DRX switching operations as indicated by scheduling information from UCI. simulation results confirm the effectiveness of our scheme. © 1997-2012 IEEE.

关键词： Information management

来源：评论

学校读者我要写书评

暂无评论

Large Language Models as Evolutionary Optimizers 13

Large Language Models as Evolutionary Optimizers

引用

13th IEEE Congress on Evolutionary computation, CEC 2024

作者： Liu, Shengcai Chen, Caishun Qu, Xinghua Tang, Ke Ong, Yew-Soon Southern University of Science and Technology Centre for Frontier Ai Research A∗star Department of Computer Science and Engineering China Centre for Frontier Ai Research A∗star Singapore Tianqiao & Chrissy Chen Institute China Southern University of Science and Technology Guangdong Provincial Key Laboratory of Brain-Inspired Intelligent Computation Department of Computer Science and Engineering China Nanyang Technological University Centre for Frontier Ai Research A∗star College of Computing and Data Science Singapore

ISBN: (纸本)9798350308365

Evolutionary algorithms (EAs) have achieved remarkable success in tackling complex combinatorial optimization problems. However, EAs often demand carefully-designed operators with the aid of domain expertise to achieve satisfactory performance. In this work, we present the first study on large language models (LLMs) as evolutionary combinatorial optimizers. The main advantage is that it requires minimal domain knowledge and human efforts, as well as no additional training of the model. This approach is referred to as LLM-driven EA (LMEA). Specifically, in each generation of the evolutionary search, LMEA instructs the LLM to select parent solutions from current population, and perform crossover and mutation to generate offspring solutions. Then, LMEA evaluates these new solutions and include them into the population for the next generation. LMEA is equipped with a self-adaptation mechanism that controls the temperature of the LLM. This enables it to balance between exploration and exploitation and prevents the search from getting stuck in local optima. We investigate the power of LMEA on the classical traveling salesman problems (TSPs) widely used in combinatorial optimization research. Notably, the results show that LMEA performs competitively to traditional heuristics in finding high-quality solutions on TSP instances with up to 20 nodes. Additionally, we also study the effectiveness of LLM-driven crossover/mutation and the self- adaptation mechanism in evolutionary search. In summary, our results reveal the great potentials of LLMs as evolutionary optimizers for solving combinatorial problems. We hope our research shall inspire future explorations on LLM-driven EAs for complex optimization challenges. © 2024 IEEE.

关键词： Traveling salesman problem

来源：评论

学校读者我要写书评

暂无评论

Spatiotemporal pattern of ENSO-induced modulation on landscape fires over Pacific Rim from 2001 to 2020

引用

Advances in Climate Change Research 2024年第6期15卷 1057-1066页

作者： Fang-Zhou LI Ning-Ran LI Martin J.WOOSTER Wen-Shi LIN Tao XUE Tong ZHU State Key Joint Laboratory of Environment Simulation and Pollution Control College of Environmental Sciences and EngineeringPeking UniversityBeijing 100871China State Environmental Protection Key Laboratory of Atmospheric Exposure and Health Risk Management and Center for Environment and HealthPeking UniversityBeijing 100871China School of Science Swinburne University of TechnologyMelbourne VIC 3122Australia Leverhulme Centre for Wildfires Environment&SocietyDepartment of GeographyKing's College LondonLondon WC2R 2LSUK NERC National Centre for Earth Observation Department of GeographyKing's College LondonLondon WC2R 2LSUK School of Atmospheric Sciences Sun Yat-sen UniversitySouthern Marine Science and Engineering Guangdong Laboratory(Zhuhai)Zhuhai 519000China Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies Sun Yat-sen UniversityZhuhai 519000China Institute of Reproductive and Child Health National Health Commission Key Laboratory of Reproductive Health/Department of Epidemiology and BiostatisticsMinistry of Education Key Laboratory of Epidemiology of Major Diseases(PKU)School of Public HealthPeking University Health Science CentreBeijing 100191China Research Station of Alpine Ecology Environment and Health Tibet UniversityLhasa 850000China

While El Niño-Southern Oscillation(ENSO)modulates landscape fire activities across the Pacific Rim,the detailed patterns and mode-specific variations of these effects remain poorly *** study aims to address that gap by systematically assessing the spatiotemporal variations in burned areas from 2001 to 2020 during different modes of ENSO,namely,Eastern Pacific(EP)El Niño,EP La Niña,Central Pacific(CP)El Niño and CP La Niñ*** evaluate the modulation patterns using classical correlation and cross-spectrum analyses,focusing on five hotspot regions:Temperate North America(TENA),Southern Hemisphere South America(SHSA),Northern Hemisphere South America(NHSA),Equatorial Asia(EQAS)and Australia and New Zealand(AUST).El Niño and La Niña exhibit asymmetrical opposite effects on burned areas,as *** findings reveal spatial non-uniformity in the impact of ENSO on landscape fires,with La Niña enhancing burned areas in TENA and SHSA,whereas El Niño predominantly affects AUST,EQAS and *** and EP ENSO events differ in intensity and their large-scale circulation *** differences cause notable variations in the regional burned *** vapour redistribution emerges as the key *** study emphasises the heterogeneity in ENSO modes in regulating landscape fires,providing insights for future landscape fire risk assessment and prevention efforts under climate change.

关键词： ENSO mode Landscape fire Burned area Pacific Rim

来源：评论

学校读者我要写书评

暂无评论

A Simultaneous Wireless Information and Power Transfer-based Multi-hop Clustering Routing Protocol for RF Energy Harvesting-Cognitive Radio Sensor Networks

Journal of Network Intelligence

引用

Journal of Network Intelligence 2023年第3期8卷 991-1007页

作者： Wang, Ji-Hong Su, Xi-Tong Ge, Yi-Yang Chen, Yeh-Cheng Key Laboratory of Modern Power System Simulation and Control & Renewable Energy Technology Ministry of Education Northeast Electric Power University China School of Electrical Engineering Northeast Electric Power University 169 Changchun Road Jilin132012 China Department of Computer Science University of California DavisCA001313 United States

Radio frequency energy harvesting (RF EH) and clustering are promising solutions to solve the energy constraint problem faced by cognitive radio sensor networks (CRSNs). However, study on clustering routing protocol design for RF EH-CRSNs is still in the initial stage, and there lacks of solutions for inter-cluster routing problem, which restricts the network scalability. In addition, unbalanced harvested energy and energy consumption may result in premature death of nodes in key position, which will significantly reduce the network performance. In this paper, a simultaneous wireless information and power transfer (SWIPT)-based multi-hop clustering routing protocol (SMCRP) is proposed for RF EH-CRSNs to well balance the residual energy distribution among nodes and postpone node death. Apart from the RF energy harvested from dedicated or ambi-ent energy sources, the energy obtained through intra-cluster and inter-cluster SWIPT is also considered to facilitate high-quality cluster heads selection, cluster formation and inter-cluster route establishment. Power splitting ratio is derived based on the residual energy of CRSNs nodes and their energy consumption to enable effective implementation of SWIPT in CRSNs. simulation results show that SMCRP is effective in balancing the residual energy distribution among nodes and improving node sustainability. To be specific, compared with current clustering protocols, the network lifetime is extended by 64.07% while intra-cluster energy balance degree and network energy balance degree are improved by 15.1% and 7.82%, respectively. © 2023 ISSN 2414-8105 (Online).

关键词： Cognitive radio

来源：评论

学校读者我要写书评

暂无评论

A Simple Graph Contrastive Learning Framework for Short Text Classification

arXiv

引用

arXiv 2025年

作者： Liu, Yonghao Giunchiglia, Fausto Huang, Lan Li, Ximing Feng, Xiaoyue Guan, Renchu Key Laboratory of Symbolic Computation and Knowledge Engineering of the Ministry of Education College of Computer Science and Technology Jilin University China University of Trento Italy

Short text classification has gained significant attention in the information age due to its prevalence and real-world applications. Recent advancements in graph learning combined with contrastive learning have shown promising results in addressing the challenges of semantic sparsity and limited labeled data in short text classification. However, existing models have certain limitations. They rely on explicit data augmentation techniques to generate contrastive views, resulting in semantic corruption and noise. Additionally, these models only focus on learning the intrinsic consistency between the generated views, neglecting valuable discriminative information from other potential views. To address these issues, we propose a Simple graph contrastive learning framework for Short Text Classification (SimSTC). Our approach involves performing graph learning on multiple text-related component graphs to obtain multi-view text embeddings. Subsequently, we directly apply contrastive learning on these embeddings. Notably, our method eliminates the need for data augmentation operations to generate contrastive views while still leveraging the benefits of multi-view contrastive learning. Despite its simplicity, our model achieves outstanding performance, surpassing large language models on various datasets. Copyright © 2025, The Authors. All rights reserved.

关键词： Contrastive Learning

来源：评论

学校读者我要写书评

暂无评论

Oxidation Mechanism and Toxicity Evolution of Linalool,a Typical Indoor Volatile Chemical Product

引用

Environment & Health 2024年第7期2卷 486-498页

作者： Zihao Fu Song Guo Ying Yu Hong-Bin Xie Shiyu Li Daqi Lv Putian Zhou Kai Song Zheng Chen Rui Tan Kun Hu Ruizhe Shen Maosheng Yao Min Hu State Key Joint Laboratory of Environmental Simulation and Pollution Control International Joint Laboratory for Regional Pollution ControlMinistry of Education(IJRC)College of Environmental Sciences and EngineeringPeking UniversityBeijing 100871China Collaborative Innovation Center of Atmospheric Environment and Equipment Technology Nanjing University of Information Science&TechnologyNanjing 210044China Key Laboratory of Industrial Ecology and Environmental Engineering(Ministry of Education) School of Environmental Science and TechnologyDalian University of TechnologyDalian 116024China Institute for Atmospheric and Earth System Research/Physics Faculty of ScienceUniversity of HelsinkiP.O.Box 64FIN-00014 HelsinkiFinland

Linalool,a high-reactivity volatile chemical product(VCP)commonly found in cleaning products and disinfectants,is increasingly recognized as an emerging contaminant,especially in indoor *** the gas-phase oxidation mechanism of linalool is crucial for assessing its impact on atmospheric chemistry and human *** quantum chemical calculations and computational toxicology simulations,we investigated the atmospheric transformation and toxicity evolution of linalool under low and high NO/HO_(2)·levels,representing indoor and outdoor *** findings reveal that linalool can undergo the novel mechanisms involving concerted peroxy(RO_(2)·)and alkoxy radical(RO·)modulated autoxidation,particularly emphasizing the importance of cyclization reactions *** expands the widely known RO_(2)·-dominated H-shift-driven autoxidation and proposes a generalized autoxidation mechanism that leads to the formation of low-volatility secondary organic aerosol(SOA)*** analysis shows that over half of transformation products(TPs)exhibited higher carcinogenicity and respiratory toxicity compared to *** also propose time-dependent toxic effects of TPs to assess their long-term *** results indicate that the strong indoor emission coupled with slow consumption rates lead to significant health risks under an indoor *** results highlight complex indoor air chemistry and health concerns regarding persistent toxic products during indoor cleaning,which involves the use of linalool or other VCPs.

关键词： volatile chemical products(VCPs) peroxy radicals(RO_(2)·) atmospheric autoxidation secondary organic aerosol(SOA) computational toxicology

来源：评论

学校读者我要写书评

暂无评论

Efficient numerical methods for computing stationary states of spherical Landau-Brazovskii model

arXiv

引用

arXiv 2025年

作者： Qiu, Qun Si, Wei Ji, Guanghua Jiang, Kai School of Mathematical Sciences Beijing Normal University Beijing100875 China School of Mathematics Sciences Peking University Beijing100871 China School of Mathematics and Computational Science Hunan Key Laboratory for Computation and Simulation in Science and Engineering Key Laboratory of Intelligent Computing and Information Processing of Ministry of Education Xiangtan University Hunan Xiangtan411105 China

In this paper, we develop a set of efficient methods to compute stationary states of the spherical Landau-Brazovskii (LB) model in a discretization-then-optimization way. First, we discretize the spherical LB energy functional into a finite-dimensional energy function by the spherical harmonic expansion. Then five optimization methods are developed to compute stationary states of the discretized energy function, including the accelerated adaptive Bregman proximal gradient, Nesterov, adaptive Nesterov, adaptive nonlinear conjugate gradient and adaptive gradient descent methods. To speed up the convergence, we propose a principal mode analysis (PMA) method to estimate good initial configurations and sphere radius. The PMA method also reveals the relationship between the optimal sphere radius and the dominant degree of spherical harmonics. Numerical experiments show that our approaches significantly reduce the number of iterations and the computational time. Copyright © 2025, The Authors. All rights reserved.

关键词： Conjugate gradient method

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：