检索结果-内蒙古大学图书馆

RKDG Methods with Multi-resolution WENO Limiters for Solving Steady-State Problems on Triangular Meshes

Communications on Applied Mathematics and Computation 2024年第3期6卷 1575-1599页

作者： Jun Zhu Chi-Wang Shu Jianxian Qiu State Key Laboratory of Mechanics and Control of Mechanical Structures and Key Laboratory of Mathematical Modelling and High Performance Computing of Air Vehicles(NUAA) MIITNanjing University of Aeronautics and AstronauticsNanjing 210016JiangsuChina Division of Applied Mathematics Brown UniversityProvidenceRI 02912USA School of Mathematical Sciences and Fujian Provincial Key Laboratory of Mathematical Modeling and High-Performance Scientific ComputingXiamen UniversityXiamen 361005FujianChina

In this paper, we design high-order Runge-Kutta discontinuous Galerkin (RKDG) methods with multi-resolution weighted essentially non-oscillatory (multi-resolution WENO) limiters to compute compressible steady-state problems on triangular meshes. A troubled cell indicator extended from structured meshes to unstructured meshes is constructed to identify triangular cells in which the application of the limiting procedures is required. In such troubled cells, the multi-resolution WENO limiting methods are used to the hierarchical L^(2) projection polynomial sequence of the DG solution. Through using the RKDG methods with multi-resolution WENO limiters, the optimal high-order accuracy can be gradually reduced to first-order in the triangular troubled cells, so that the shock wave oscillations can be well suppressed. In steady-state simulations on triangular meshes, the numerical residual converges to near machine zero. The proposed spatial reconstruction methods enhance the robustness of classical DG methods on triangular meshes. The good results of these RKDG methods with multi-resolution WENO limiters are verified by a series of two-dimensional steady-state problems.

关键词： RKDG method Steady-state problem Multi-resolution WENO limiter Triangular mesh Machine zero

来源：评论

学校读者我要写书评

暂无评论

DISCRETE ENERGY ANALYSIS OF THE THIRD-ORDER VARIABLE-STEP BDF TIME-STEPPING FOR DIFFUSION EQUATIONS

引用

Journal of Computational Mathematics 2023年第2期41卷 325-344页

作者： Hong-lin Liao Tao Tang Tao Zhou Department of Mathematics Nanjing University of Aeronautics and AstronauticsNanjing 211106China Key Laboratory of Mathematical Modelling and High Performance Computing of Air Vehicles(NUAA) MIITNanjing 211106China Division of Science and Technology BNU-HKBU United International CollegeZhuhai 519087China Institute of Computational Mathematics and Scientific/Engineering Computing Academy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing100190China

This is one of our series works on discrete energy analysis of the variable-step BDF *** this part,we present stability and convergence analysis of the third-order BDF(BDF3)schemes with variable steps for linear diffusion equations,see,e.g.,[SIAM ***.,58:2294-2314]and[***.,90:1207-1226]for our previous works on the BDF2 *** this aim,we first build up a discrete gradient structure of the variable-step BDF3 formula under the condition that the adjacent step ratios are less than 1.4877,by which we can establish a discrete energy dissipation ***-robust stability and convergence analysis in the L^(2) norm are then *** the mesh robustness means that the solution errors are well controlled by the maximum time-step size but independent of the adjacent time-step *** also present numerical tests to support our theoretical results.

关键词： Diffusion equations Variable-step third-order BDF scheme Discrete gradient structure Discrete orthogonal convolution kernels Stability and convergence

来源：评论

学校读者我要写书评

暂无评论

Mean square stability of stochastic theta method for stochastic differential equations driven by fractional Brownian motion

arXiv

引用

arXiv 2021年

作者： Li, Min Hu, Yaozhong Huang, Chengming Wang, Xiong School of Mathematics and Physics Center for Mathematical Sciences China University of Geosciences Wuhan China Department of Mathematical and Statistical Sciences University of Alberta Edmonton Canada School of Mathematics and Statistics Hubei Key Laboratory of Engineering Modelling and Scientific Computing Huazhong University of Science and Technology Wuhan China

In this paper, we study the mean square stability of the solution and its stochastic theta scheme for the following stochastic differential equations drive by fractional Brownian motion with Hurst parameter H ∈ (1/2,1): dX(t) = f(t,X(t))dt+g(t,X(t))dBH(t). Firstly, we consider the special case when f(t,X) = −λκtκ-1X and g(t,X) = µX. The solution is explicit and is mean square stable when κ ≥ 2H. It is proved that if the parameter 2H ≤ κ ≤ 3/2 and √3/2·e/√3/2·e+1 (≈ 0.77) ≤ θ ≤ 1 or κ > 3/2 and 1/2 MSC Codes 65C30, 65L20, 60G22, 60H10, 33C15 Copyright © 2021, The Authors. All rights reserved.

关键词： Stochastic systems

来源：评论

学校读者我要写书评

暂无评论

Randomized double and triple Kaczmarz for solving extended normal equations

arXiv

引用

arXiv 2020年

作者： Du, Kui Sun, Xiao-Hui School of Mathematical Sciences Fujian Provincial Key Laboratory of Mathematical Modelling and High Performance Scientific Computing Xiamen University Xiamen361005 China School of Mathematical Sciences Xiamen University Xiamen361005 China

The randomized Kaczmarz algorithm has received considerable attention recently because of its simplicity, speed, and the ability to approximately solve large-scale linear systems of equations. In this paper we propose randomized double and triple Kaczmarz algorithms to solve extended normal equations of the form A>Ax = A>b − c. The proposed algorithms avoid forming A>A explicitly and work for arbitrary A ∈ Rm×n (full rank or rank deficient, m ≥ n or m Copyright © 2020, The Authors. All rights reserved.

关键词： Linear systems

来源：评论

学校读者我要写书评

暂无评论

Redefining pandemic preparedness:Multidisciplinary insights from the CERP modelling workshop in infectious diseases,workshop report

引用

Infectious Disease modelling 2024年第2期9卷 501-518页

作者： Marta C.Nunes Edward Thommes Holger Fröhlich Antoine Flahault Julien Arino Marc Baguelin Matthew Biggerstaff Gaston Bizel-Bizellot Rebecca Borchering Giacomo Cacciapaglia Simon Cauchemez Alex Barbier-Chebbah Carsten Claussen Christine Choirat Monica Cojocaru Catherine Commaille-Chapus Chitin Hon Jude Kong Nicolas Lambert Katharina B.Lauer Thorsten Lehr Cédric Mahe Vincent Marechal Adel Mebarki Seyed Moghadas Rene Niehus Lulla Opatowski Francesco Parino Gery Pruvost Andreas Schuppert Rodolphe Thiébaut Andrea Thomas-Bachli Cecile Viboud Jianhong Wu Pascal Crépey Laurent Coudeville Center of Excellence in Respiratory Pathogens(CERP) Hospices Civils de Lyon(HCL)and Centre International de Recherche en Infectiologie(CIRI)Équipe SantéPubliqueÉpidémiologie etÉcologieÉvolutive des Maladies Infectieuses(PHE3ID)Inserm U1111CNRS UMR5308ENS de LyonUniversitéClaude Bernard Lyon 1LyonFrance South African Medical Research Council Vaccines&Infectious Diseases Analytics Research UnitFaculty of Health SciencesUniversity of the WitwatersrandJohannesburgSouth Africa New Products and Innovation(NPI) Sanofi Vaccines(Global)TorontoOntarioCanada Department of Mathematics and Statistics University of GuelphGuelphOntarioCanada Fraunhofer Institute for Algorithms and Scientific Computing(SCAI) Department of BioinformaticsSchloss BirlinghovenSankt AugustinGermany University of Bonn Bonn-Aachen International Center for IT(b-it)BonnGermany Institute of Global Health Faculty of MedicineUniversity of GenevaGenevaSwitzerland and Swiss School of Public HealthZürichSwitzerland Department of Mathematics University of ManitobaWinnipegManitobaCanada MRC Centre for Global Infectious Disease Analysis School of Public HealthImperial College LondonLondonUK Centre for Mathematical Modelling of Infectious Diseases Department of Infectious Disease EpidemiologyLondon School of Hygiene&Tropical MedicineLondonUK National Center for Immunization and Respiratory Diseases(NCIRD) US Centers for Disease Control and Prevention(CDC)AtlantaGAUSA Departement of Computational Biology Departement of Global HealthInstitut PasteurParisFrance Institut de Physique des Deux Infinis de Lyon(IP2I) UMR5822IN2P3/CNRSUniversitéClaude Bernard Lyon 1VilleurbanneFrance Mathematical Modelling of Infectious Diseases Unit Institut PasteurUniversitéParis CitéUMR2000 CNRSParisFrance Decision and Bayesian Computation Institut PasteurUniversitéParis CitéCNRS UMR 3571France Fraunhofer-Institute for Translational Medicine and Pharmacology HamburgGermany Institute of Global Health Faculty of MedicineUniversity of

In July 2023,the Center of Excellence in Respiratory Pathogens organized a two-day workshop on infectious diseases modelling and the lessons learnt from the Covid-19 *** report summarizes the rich discussions that occurred during the *** workshop participants discussed multisource data integration and highlighted the benefits of combining traditional surveillance with more novel data sources like mobility data,social media,and wastewater *** advancements were noted in the development of predictive models,with examples from various countries showcasing the use of machine learning and artificial intelligence in detecting and monitoring disease *** role of open collaboration between various stakeholders in modelling was stressed,advocating for the continuation of such partnerships beyond the pandemic.A major gap identified was the absence of a common international framework for data sharing,which is crucial for global pandemic ***,the workshop underscored the need for robust,adaptable modelling frameworks and the integration of different data sources and collaboration across sectors,as key elements in enhancing future pandemic response and preparedness.

关键词： modelling Covid-19 Infectious diseases Pandemic preparedness Workshop

来源：评论

学校读者我要写书评

暂无评论

Numerical methods for stochastic Volterra integral equations with weakly singular kernels

arXiv

引用

arXiv 2020年

作者： Li, Min Huang, Chengming Hu, Yaozhong School of Mathematics and Statistics Huazhong University of Science and Technology Wuhan430074 China Hubei Key Laboratory of Engineering Modelling and Scientific Computing Huazhong University of Science and Technology Wuhan430074 China Department of Mathematical and Statistical Sciences University of Alberta EdmontonT6G 2G1 Canada

In this paper, we first establish the existence, uniqueness and Hölder continuity of the solution to stochastic Volterra integral equations with weakly singular kernels. Then, we propose a θ-Euler-Maruyama scheme and a Milstein scheme to solve the equations numerically and we obtain the strong rates of convergence for both schemes in Lp norm for any p ≥ 1. For the θ-Euler-Maruyama scheme the rate is min{1 − α, 12 − β} and for the Milstein scheme the rate is min{1 − α, 1 − 2β} when α, 12, where (0 12 ). These results on the rates of convergence are significantly different from that of the similar schemes for the stochastic Volterra integral equations with regular kernels. The difficulty to obtain our results is the lack of Itô formula for the equations. To get around of this difficulty we use instead the Taylor formula and then carry a sophisticated analysis on the equation the solution satisfies. Copyright © 2020, The Authors. All rights reserved.

关键词： Integral equations

来源：评论

学校读者我要写书评

暂无评论

Twofold saddle-point formulation of biot poroelasticity with stress-dependent diffusion

arXiv

引用

arXiv 2021年

作者： Gómez-Vargas, Bryan Mardal, Kent-André Ruiz-Baier, Ricardo Vinje, Vegard Sección de Matemática Sede de Occidente Universidad de Costa Rica San Ramón Ala juela Costa Rica Department of Mathematics Division of Mechanics University of Oslo Norway Simula Research Laboratory Lysaker1325 Norway School of Mathematics Monash University 9 Rainforest Walk MelbourneVIC3800 Australia Institute of Computer Science and Mathematical Modelling Sechenov University Moscow Russia Universidad Adventista de Chile Casilla 7-D Chillán Chile Department for Numerical Analysis and Scientific Computing Simula Research Laboratory Lysaker Norway

We introduce a stress/total-pressure formulation for poroelasticity that includes the coupling with steady nonlinear diffusion modified by stress. The nonlinear problem is written in mixed-primal form, coupling a perturbed twofold saddle-point system with an elliptic problem. The continuous formulation is analysed in the framework of abstract fixed-point theory and Fredholm alternative for compact operators. A mixed finite element method is proposed and its stability and convergence analysis are carried out. We also include a few illustrative numerical tests. The resulting model can be used to study waste removal in the brain parenchyma, where diffusion of a tracer alone or a combination of advection and diffusion are not sufficient to explain the alterations in rates of filtration observed in porous media *** Codes 65N60, 92C50 © 2021, CC BY.

关键词： Diffusion

来源：评论

学校读者我要写书评

暂无评论

Combined effects of hydrometeorological hazards and urbanisation on dengue risk in Brazil: a spatiotemporal modelling study

引用

The Lancet Planetary Health 2021年第4期5卷 e209-e219页

作者： Lowe, Rachel Lee, Sophie A Brady, Oliver J Bastos, Leonardo Carrasco-Escobar, Gabriel de Castro Catão, Rafael Colón-González, Felipe J Barcellos, Christovam Carvalho, Marilia Sá Blangiardo, Marta Rue, Håvard Gasparrini, Antonio Centre for Mathematical Modelling of Infectious Diseases London School of Hygiene & Tropical Medicine London United Kingdom Centre on Climate Change and Planetary Health London School of Hygiene & Tropical Medicine London United Kingdom Department of Infectious Disease Epidemiology London School of Hygiene & Tropical Medicine London United Kingdom Department of Public Health Environments and Society London School of Hygiene & Tropical Medicine London United Kingdom Centre for Statistical Modelling London School of Hygiene & Tropical Medicine London United Kingdom Scientific Computing Program Oswaldo Cruz Foundation Rio de Janeiro Brazil Health Information and Communication Institute Oswaldo Cruz Foundation Rio de Janeiro Brazil Scripps Institution of Oceanography University of California San Diego San Diego CA United States Health Innovation Laboratory Institute of Tropical Medicine Alexander von Humboldt Universidad Peruana Cayetano Heredia Lima Peru Department of Geography Federal University of Espírito Santo Vitória Brazil MRC Centre for Environment and Health Department of Epidemiology and Biostatistics Imperial College London London United Kingdom Statistics Program Computer Electrical and Mathematical Sciences and Engineering Division King Abdullah University of Science and Technology Thuwal Saudi Arabia

Background: Temperature and rainfall patterns are known to influence seasonal patterns of dengue transmission. However, the effect of severe drought and extremely wet conditions on the timing and intensity of dengue epidemics is poorly understood. In this study, we aimed to quantify the non-linear and delayed effects of extreme hydrometeorological hazards on dengue risk by level of urbanisation in Brazil using a spatiotemporal model. Methods: We combined distributed lag non-linear models with a spatiotemporal Bayesian hierarchical model framework to determine the exposure-lag-response association between the relative risk (RR) of dengue and a drought severity index. We fit the model to monthly dengue case data for the 558 microregions of Brazil between January, 2001, and January, 2019, accounting for unobserved confounding factors, spatial autocorrelation, seasonality, and interannual variability. We assessed the variation in RR by level of urbanisation through an interaction between the drought severity index and urbanisation. We also assessed the effect of hydrometeorological hazards on dengue risk in areas with a high frequency of water supply shortages. Findings: The dataset included 12 895 293 dengue cases reported between 2001 and 2019 in Brazil. Overall, the risk of dengue increased between 0–3 months after extremely wet conditions (maximum RR at 1 month lag 1·56 [95% CI 1·41–1·73]) and 3–5 months after drought conditions (maximum RR at 4 months lag 1·43 [1·22–1·67]). Including a linear interaction between the drought severity index and level of urbanisation improved the model fit and showed the risk of dengue was higher in more rural areas than highly urbanised areas during extremely wet conditions (maximum RR 1·77 [1·32–2·37] at 0 months lag vs maximum RR 1·58 [1·39–1·81] at 2 months lag), but higher in highly urbanised areas than rural areas after extreme drought (maximum RR 1·60 [1·33–1·92] vs 1·15 [1·08–1·22], both at 4 months lag). We also found the den

关键词：

来源：评论

学校读者我要写书评

暂无评论

Mycorrhizal symbioses and tree diversity in global forest communities

引用

Science Advances 2025年第24期11卷 eadt5743页

作者： Feng Jiang Xucai Pu Bernhard Schmid Peter B. Reich Jingjing Liang Akane O. Abbasi Jesús Aguirre-Gutiérrez Angelica Maria Almeyda Zambrano Jan Altman Juan Gabriel Álvarez-González Luciana F. Alves Bienvenu H. K. Amani Christian Ammer Gerardo A. Aymard Naveen Babu Kanda Meredith L. Bastian Jean-Francois Bastin Marijn Bauters Pascal Boeckx Svetlana N. Bondarchuk Alexander Bondarev Francis Q. Brearley Sophie Brennan Jaime Briseño-Reyes Eben N. Broadbent Goran Češljar Han Y. H. Chen Chelsea Chisholm WookJin Choi Emil Cienciala Connie J. Clark Alessio Collalti José Javier Corral-Rivas Javid Ahmad Dar Selvadurai Dayanandan Sergio de-Miguel Ashaq Ahmad Dar Géraldine Derroire Ilija Djordjevic Tran Van Do Jiří Doležal Aurélie Dourdain Teresa Eyre Adandé Belarmain Fandohan Lorenzo Frizzera Roberto Cazzolla Gatti Damiano Gianelle M. Socorro González Elizondo Elisa Grieco David J. Harris Andy Hector Bruno Hérault Cang Hui Nobuo Imai Andrzej M. Jagodziński Chengjun Ji Lin Jiang Carlos A. Joly Viktor N. Karminov Kuswata Kartawinata Justin N. Kassi Elizabeth Kearsley Gunnar Keppel Mohammed Latif Khan Carine Klauberg Kirill A. Korznikov Subashree Kothandaraman Florian Kraxner Leonid Krivobokov Dmitry Kucher Amit Kumar Anna Kvashnina Gaia Vaglio Laurin Rodrigo Vieira Leite Moses B. Libalah Ekaterina S. Lonkina Huicui Lu Shan Luo Yuan Luo Emma Mackintosh Andrew R. Marshall Rodolfo Vásquez Martínez Radim Matula William McDonald Ayyappan Narayanan María Guadalupe Nava-Miranda Jagadeesan Naveenkumar Abel Monteagudo Mendoza Stanisław Miścicki Tatyana Moskalyuk Liudmila Mukhortova Sharif A. Mukul Gert-Jan Nabuurs Victor J. Neldner Radovan Nevenic Anny E. N’Guessan Michael Ngugi Alain Paquette Elena I. Parfenova Marc Parren Narayanaswamy Parthasarathy Pablo L. Peri Sebastian Pfautsch Maria T. F. Piedade Galina Polyakova Axel Dalberg Poulsen John R. Poulsen Hans Pretzsch Mirco Rodeghiero Ervan Rutishauser Purabi Saikia Philippe Saner Dmitry Schepaschenko Jochen Schöngart Eric B. Searle Douglas Sheil Zehao Shen Stephanie Shooner Anatoly Sh Institute of Ecology and State Key Laboratory for Vegetation Structure Function and Construction (VegLab) College of Urban and Environmental Sciences Peking University Beijing China. Remote Sensing Laboratories Department of Geography University of Zürich Zürich Switzerland. Department of Forest Resources University of Minnesota St Paul MN 55108 USA. Hawkesbury Institute for the Environment Western Sydney University Penrith New South Wales Australia. Institute for Global Change Biology and School for Environment and Sustainability University of Michigan Ann Arbor MI 48109 USA. Forest Advanced Computing and Artificial Intelligence Laboratory (FACAI) Department of Forestry and Natural Resources Purdue University West Lafayette IN USA. Environmental Change Institute School of Geography and the Environment University of Oxford Oxford UK. Leverhulme Centre for Nature Recovery University of Oxford Oxford UK OX13QY. Spatial Ecology and Conservation (SPEC) Lab Center for Latin American Studies University of Florida Gainesville FL 32611 USA. Institute of Botany of the Czech Academy of Sciences Třeboň Czech Republic. Faculty of Forestry and Wood Sciences Czech University of Life Sciences Prague Czech Republic. Departamento de Ingeniería Agroforestal Universidad de Santiago de Compostela Lugo Spain. Center for Tropical Research Institute of the Environment and Sustainability University of California Los Angeles Los Angeles CA 90095 USA. Université Jean Lorougnon Guédé Unité de Formation et de Recherche en Agroforesterie BP 150 Daloa Ivory Coast. Université Nangui Abrogoua Unité de Formation et de Recherche en Sciences de la Nature 02 BP 801 Abidjan 02 Laboratoire d’Écologie et du Développement durable (LEDD) Abidjian Ivory Coast. Silviculture and Forest Ecology Georg August-University of Göttingen Göttingen Germany. UNELLEZ-Guanare Programa de Ciencias del Agro y el Mar Herbario Universitario (PORT) Portuguesa Venezuela. Jardín Botánico de Bogotá José Cele

Unraveling the mechanisms underlying the maintenance of species diversity is a central pursuit in ecology. It has been hypothesized that ectomycorrhizal (EcM) in contrast to arbuscular mycorrhizal fungi can reduce tree species diversity in local communities, which remains to be tested at the global scale. To address this gap, we analyzed global forest inventory data and revealed that the relationship between tree species richness and EcM tree proportion varied along environmental gradients. Specifically, the relationship is more negative at low latitudes and in moist conditions but is unimodal at high latitudes and in arid conditions. The negative association of EcM tree proportion on species diversity at low latitudes and in humid conditions is likely due to more negative plant-soil microbial interactions in these regions. These findings extend our knowledge on the mechanisms shaping global patterns in plant species diversity from a belowground view.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Corrigendum: Differential geometric analysis of alterations in MH α‐helices

引用

Journal of Computational Chemistry 2013年第32期34卷

作者： B. Hischenhuber H. Havlicek J. Todoric S. Höllrigl‐Binder W. Schreiner B. Knapp Center for Medical Statistics InformaticsIntelligent Systems Section for Biosimulation and Bioinformatics Medical University of ViennaVienna Austria Faculty of Mathematics and GeoinformationInstitute of Discrete Mathematics and Geometry Research Group for Differential Geometry and Geometric Structures Vienna University of TechnologyViennaAustria Laboratory of Gene Regulation and Signal Transduction Departments of Pharmacology and PathologySchool of Medicine University of CaliforniaSan Diego USA Department of Laboratory MedicineMedical University ViennaVienna Austria Faculty of Mathematics and GeoinformationInstitute of Analysis and Scientific Computing Research Group for Mathematical Modelling and Simulation Vienna University of TechnologyVienna Austria Department of StatisticsProtein Informatics Group University of OxfordOxford United Kingdom

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

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

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

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

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：