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arXiv 2024年

作者： Zheng, Nanyi Cai, Xiaofeng Qiu, Jing-Mei Qiu, Jianxian Department of Mathematical Sciences University of Delaware NewarkDE19716 United States Research Center for Mathematics Advanced Institute of Natural Sciences Beijing Normal University Zhuhai519087 China Guangdong Provincial Key Laboratory of Interdisciplinary Research and Application for Data Science BNU-HKBU United International College Zhuhai519087 China School of Mathematical Sciences Fujian Provincial Key Laboratory of Mathematical Modeling and High-Performance Scientific Computing Xiamen University Fujian Xiamen361005 China

In this paper, we develop high-order, conservative, non-splitting Eulerian-Lagrangian (EL) Runge-Kutta (RK) finite volume (FV) weighted essentially non-oscillatory (WENO) schemes for convection-diffusion equations. The proposed EL-RK-FV-WENO scheme defines modified characteristic lines and evolves the solution along them, significantly relaxing the time-step constraint for the convection term. The main algorithm design challenge arises from the complexity of constructing accurate and robust reconstructions on dynamically varying Lagrangian meshes. This reconstruction process is needed for flux evaluations on time-dependent upstream quadrilaterals and time integrations along moving characteristics. To address this, we propose a strategy that utilizes a WENO reconstruction on a fixed Eulerian mesh for spatial reconstruction, and updates intermediate solutions on the Eulerian background mesh for implicit-explicit RK temporal integration. This strategy leverages efficient reconstruction and remapping algorithms to manage the complexities of polynomial reconstructions on time-dependent quadrilaterals, while ensuring local mass conservation. The proposed scheme ensures mass conservation due to the flux-form semi-discretization and the mass-conservative reconstruction on both background and upstream cells. Extensive numerical tests have been performed to verify the effectiveness of the proposed scheme. © 2024, CC BY.

关键词： Mesh generation

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Gradient inequality and convergence of the normalized Ricci flow

arXiv

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arXiv 2021年

作者： Kavallaris, Nikos I. Suzuki, Takashi Department of Mathematical and Physical Sciences University of Chester Thornton Science Park Pool Lane Ince ChesterCH2 4NU United Kingdom Center for Mathematical Modeling and Data Science Osaka University Japan

We study the problem of convergence of the normalized Ricci flow evolving on a compact manifold Ω without boundary. In [11, 12] we derived, via PDE techniques, global-in-time existence of the classical solution and pre-compactness of the orbit. In this work we show its convergence to steady-states, using a gradient inequality of Lojasiewicz type. We have thus an alternative proof of [7], but for general manifold Ω and not only for unit sphere. As a byproduct of that approach we also derive the rate of convergence according to this steady-sate being either degenerate or non-degenerate as a critical point of a related energy *** Codes 35K55 © 2021, CC BY.

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The role of herbivores in the grassland carbon budget for Three-Rivers Headwaters region,Qinghai-Tibetan Plateau,China

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Grassland Research 2022年第3期1卷 207-219页

作者： Junbang Wang Xinquan Zhao Xihuang Ouyang Liang Zhao Wenying Wang Chan Zuo Zhenhua Zhang Huakun Zhou Alan Watson Yingnian Li Key Laboratory of Ecosystem Network Observation and Modeling National Ecosystem Science Data CenterInstitute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijingChina State Key Laboratory of Plateau Ecology and Agriculture Qinghai UniversityXiningChina Qinghai Provincial Key Laboratory of Restoration Ecology for Cold Region Northwest Institute of Plateau BiologyChinese Academy of SciencesXiningChina University of Chinese Academy of Sciences BeijingChina College of Life Sciences Qinghai Normal UniversityXiningChina Rocky Mountain Research Station USDA Forest ServiceMissoulaMontanaUSA

Background:An accurate assessment of the carbon budget is a crucial part of projecting future climate change and its impact on *** foster multiple ecological functions including support for wild animals and *** intake forage biomass carbon,then digest and metabolize,and finally retain some *** carbon processes have not been well quantified,resulting in uncertainties in the estimation of regional carbon budgets for grassland ***:An animal metabolic carbon flux model was developed for herbivores in the Three-Rivers Headwaters region of *** forage intake and metabolic carbon rates were estimated through metabolic body weight and daily digested measures for the main herbivore ***:The carbon intake was 5.52 Tg C year−1(45%)from partial aboveground biomass(12.2 Tg C year−1),in which 39.31%was released into the atmosphere by respiration CO_(2),43.77%was returned to the ecosystem as feces and urine,and 16.96%was retained in herbivores for population regeneration or for human ***:This study,as the first research on this topic,quantified the carbon flux of herbivores and found livestock accounts for a major part of consumed carbon on grasslands,which is important for understanding regional carbon budgets to mitigate and adapt to climate change over grasslands worldwide.

关键词： aboveground biomass alpine grassland carbon budget herbivores livestock metabolism

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Corrigendum and addendum to “From risk sharing to pure premium for a large number of heterogeneous losses” [Insurance: Mathematics and Economics 96 (2021) 116–126]

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Insurance: Mathematics and Economics 2021年 101卷 640-644页

作者： Michel Denuit Christian Y. Robert Institute of Statistics Biostatistics and Actuarial Science - ISBA Louvain Institute of Data Analysis and Modeling - LIDAM UCLouvain Louvain-la-Neuve Belgium Laboratory in Finance and Insurance - LFA CREST - Center for Research in Economics and Statistics ENSAE Paris France

This paper supplements the previous contribution by Denuit and Robert (2021) . First, the compound Poisson case is revisited and the strong law of large number is rigorously established for the conditional expectations defining the conditional mean risk allocation. Then, a weak law of large numbers is proposed, providing the actuary with a criterion ensuring that the variance of individual contributions tends to 0. This is appealing for applications since this behavior is a key success factor for collaborative insurance pools.

关键词： G22 Conditional expectation Risk pooling Law of large number

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Online federated learning framework for classification

arXiv

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arXiv 2025年

作者： Guo, Wenxing Xie, Jinhan Lu, Jianya Jiang, Bei Dai, Hongsheng Kong, Linglong School of Mathematics Statistics and Actuarial Science University of Essex ColchesterCO4 3SQ United Kingdom Yunnan Key Laboratory of Statistical Modeling and Data Analysis Yunnan University Kunming650091 China Department of Mathematical and Statistical Sciences University of Alberta EdmontonABT6G 2G1 Canada School of Mathematics Statistics and Physics Newcastle University Newcastle upon TyneNE1 7RU United Kingdom

In this paper, we develop a novel online federated learning framework for classification, designed to handle streaming data from multiple clients while ensuring data privacy and computational efficiency. Our method leverages the generalized distance-weighted discriminant technique, making it robust to both homogeneous and heterogeneous data distributions across clients. In particular, we develop a new optimization algorithm based on the Majorization-Minimization principle, integrated with a renewable estimation procedure, enabling efficient model updates without full retraining. We provide a theoretical guarantee for the convergence of our estimator, proving its consistency and asymptotic normality under standard regularity conditions. In addition, we establish that our method achieves Bayesian risk consistency, ensuring its reliability for classification tasks in federated environments. We further incorporate differential privacy mechanisms to enhance data security, protecting client information while maintaining model performance. Extensive numerical experiments on both simulated and real-world datasets demonstrate that our approach delivers high classification accuracy, significant computational efficiency gains, and substantial savings in data storage requirements compared to existing methods. © 2025, CC BY.

关键词： Federated learning

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Resilience to hazards overlapping a pandemic: A shelter resource stabilization model

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International Journal of Mass Emergencies & Disasters 2023年第1期41卷 164 - 173页

作者： Nicole S Hutton Jennifer L Whytlaw Joshua Behr Juita-Elena (Wie) Yusuf Taiwo C Olanrewaju Lasisi Jennifer Marshall Vicky Seiler Rimer Department of Political Science and Geography Old Dominion University Norfolk VA USA Virginia Modeling Analysis & Simulation Center Old Dominion University Norfolk VA USA School of Public Service and Institute for Coastal Adaptation and Resilience Old Dominion University Norfolk VA USA CLIR Postdoctoral Fellow in Community Data Literacy at Carnegie Mellon University Libraries PA USA College of Public Health University of South Florida FL USA Department of Marketing Old Dominion University Norfolk VA USA

COVID-19 and the resulting financial impacts had budget and workforce implications for organizations involved in emergency shelter provision. To address distancing and sanitation protocols as well as virus transmission and vaccination rates, shelter supplies, facility modifications, and staffing adjustments were needed. As funding and authorizations to implement public health guidance and stabilize the workforce expired, emergency managers had to determine whether to continue pandemic protocols. In order to understand these relationships, we conducted a workshop in September 2021 with 137 emergency managers, public health leaders, and other government and nonprofit practitioners from 20 states, the U.S. Virgin Islands, and Canada to identify resource reallocation strategies utilized for sheltering from post-lockdown to post-vaccine periods of the COVID-19 pandemic. We applied a fiscal recovery framework to explore how these operational changes were influenced by and have implications for fiscal and policy support as well as operational adaptability. Results show that as fiscal and policy support waned, some pandemic protocols were suspended, thereby shifting and reducing human and facility resource needs. Distancing protocols benefited from improvements in masking, vaccine, and testing availability without consistent mandates, but non-congregate shelter provision was reduced as authorizations and funding expired. Modified service contracts and increased utilization of special needs registries can realign resources with health and safety needs. Based on participant responses, we developed a Retractable Stabilization Model to indicate how shelter resources can be reallocated and supported by future policy interventions to provide a range of emergency sheltering options during pandemics and overlapping hazards.

关键词： Pandemic hazard resilience emergency shelter

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Sentence Generation from IMU-based Human Whole-Body Motions in Daily Life Behaviors

Sentence Generation from IMU-based Human Whole-Body Motions ...

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IEEE/SICE International Symposium on System Integration

作者： Wataru Takano Center for Mathematical Modeling and Data Science Mathematics and Computer Science Osaka University 1-3 Machikaneyamacho Toyonaka Japan

ISBN: (数字)9781728166674

ISBN: (纸本)9781728166681

This paper presents a probabilistic approach to-ward integrating human whole-body motions with natural language. Human whole-body motions in daily life are recorded by inertial measurement units (IMU) and subsequently encoded into motion symbols. Sentences are manually attached to the human motion primitives for their annotation. Two aspects of semantics and syntactics are represented by probabilistic graphical models. One probabilistic model trains the linking of motion symbols to words, and the other model represents sentence structure as word sequences. These two models are useful toward translating human whole-body motions into descriptions, where multiple words are associated from the human motions by the first model, and the second model searches for syntactically consistent sentences consisting of the associated words. The proposed approach was tested on a large dataset of human whole-body motions and sentences to annotate these motions. The linking of human motions to natural language enables robots to understand observations of human behavior as sentences.

关键词： Probabilistic logic Mathematical model Robot sensing systems Graphical models Optical variables measurement Natural languages

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Approximate Bayesian computational methods to estimate the strength of divergent selection in population genomics models

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Journal of Computational Mathematics and data science 2024年 10卷 100091页

作者： Lukaszewicz, Martyna Issaka Salia, Ousseini Hohenlohe, Paul A. Buzbas, Erkan O. Institute for Interdisciplinary Data Sciences (IIDS) University of Idaho Moscow ID United States Department of Mathematics and Statistical Science University of Idaho Moscow ID United States Department of Biological Sciences University of Idaho Moscow ID United States Institute for Modeling Collaboration and Innovation (IMCI) University of Idaho Moscow ID United States Department of Horticulture Washington State University Pullman WA United States

Statistical estimation of parameters in large models of evolutionary processes is often too computationally inefficient to pursue using exact model likelihoods, even with single-nucleotide polymorphism (SNP) data, which offers a way to reduce the size of genetic data while retaining relevant information. Approximate Bayesian Computation (ABC) to perform statistical inference about parameters of large models takes the advantage of simulations to bypass direct evaluation of model likelihoods. We develop a mechanistic model to simulate forward-in-time divergent selection with variable migration rates, modes of reproduction (sexual, asexual), length and number of migration-selection cycles. We investigate the computational feasibility of ABC to perform statistical inference and study the quality of estimates on the position of loci under selection and the strength of selection. To expand the parameter space of positions under selection, we enhance the model by implementing an outlier scan on summarized observed data. We evaluate the usefulness of summary statistics well-known to capture the strength of selection, and assess their informativeness under divergent selection. We also evaluate the effect of genetic drift with respect to an idealized deterministic model with single-locus selection. We discuss the role of the recombination rate as a confounding factor in estimating the strength of divergent selection, and emphasize its importance in break down of linkage disequilibrium (LD). We answer the question for which part of the parameter space of the model we recover strong signal for estimating the selection, and determine whether population differentiation-based summary statistics or LD–based summary statistics perform well in estimating selection. © 2024 The Author(s)

关键词： ABC Joint parameters estimation Kernel Mechanistic model Population genomics Summary statistics

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Structure-preserving interpolation of quadratic-bilinear systems via regular multivariate transfer functions

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PAMM 2024年第3期24卷

作者： Peter Benner Serkan Gugercin Steffen W. R. Werner Max Planck Institute for Dynamics of Complex Technical Systems Magdeburg Germany Faculty of Mathematics Otto von Guericke University Magdeburg Magdeburg Germany Division of Computational Modeling and Data Analytics Department of Mathematics Academy of Data Science Virginia Tech Blacksburg Virginia USA

For the accurate modeling of real-world phenomena, high-dimensional nonlinear dynamical systems are indispensable. Quadratic-bilinear nonlinearities are of particular importance since many systems with general nonlinearities can be remodeled into this form. Such nonlinear systems typically encode physical properties via their internal differential structure. This leads to a high demand for structure-preserving model order reduction techniques for quadratic-bilinear systems that allow for the accurate representation of their dynamics by a small number of differential equations while retaining the internal system structure. In this paper, we provide formulae for structured regular subsystem transfer functions of quadratic-bilinear systems with internal differential structures and provide a corresponding interpolation theory for the efficient construction of the resulting structured reduced-order models. The presented theoretical results are illustrated in numerical experiments including a time-delayed nonlinear reaction–diffusion equation and a molecular simulation.

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Development of a daily soil moisture product for the period of2002–2011 in Chinese mainland

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science China Earth sciences 2020年第8期63卷 1113-1125页

作者： Kun YANG Yingying CHEN Jie HE Long ZHAO Hui LU Jun QIN Donghai ZHENG Xin LI Ministry of Education Key Laboratory for Earth System Modeling Department of Earth System ScienceTsinghua UniversityBeijing 100084China National Tibetan Plateau Data Center Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China Center for Excellence in Tibetan Plateau Earth Sciences Chinese Academy of SciencesBeijing 100101China School of Geographical Sciences Southwest UniversityChongqing 400715China

Soil moisture is an essential climate variable(ECV) concerned widely. Due to its high spatial variability, it is costly to measure soil moisture at tens of kilometers scale. In this study, a ten-year(2002–2011) daily soil moisture dataset at 0.25° spatial resolution for Chinese mainland was produced through assimilating the Advanced Microwave Scanning Radiometer for Earth Observing System(AMSR-E) brightness temperature(TB) data into a land surface model(LSM). The obtained soil moisture data was evaluated against soil moisture-measuring networks deployed in two wet areas and one dry area of the Tibetan *** results show that for the wet areas the accuracy of the soil moisture product obtained from the assimilation is considerably higher than that of both AMSR-E official soil moisture products and land surface simulation results, and for the dry area their accuracy is comparable to each other. The spatial pattern of the soil moisture from the new product is consistent with that of soil porosity from an independent survey-based dataset, further confirming the credibility of the new product. According to this product, the transition regions in China show stronger seasonal variation of soil moisture than dry and wet regions, and drier regions have stronger inter-annual variability of soil moisture than wetter regions, particularly during transitional seasons(spring and autumn). The soil moisture product is accessible at the National Tibetan Plateau data Center.

关键词： Soil moisture Microwave signal data assimilation Spatiotemporal variability Tibetan Plateau

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