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Bilinear Forms for the Recovery-Based Discontinuous Galerkin Method for Diffusion

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Communications in Computational Physics 2009年第2期5卷 683-693页

作者： Marc van Raalte Bram van Leer centrum voor wiskunde en informatica P.O.Box 940791090 GB AmsterdamThe Netherlands W.M.Keck Foundation Laboratory for Computational Fluid Dynamics Department of Aerospace EngineeringThe University of MichiganAnn ArborMI 48109-2140USA

The present paper introduces bilinear forms that are equivalent to the recovery-based discontinuous Galerkin formulation introduced by Van Leer in *** recovery method approximates the solution of the diffusion equation in a discontinuous function space,while inter-element coupling is achieved by a local L_(2)projection that recovers a smooth continuous function underlying the discontinuous *** we introduce the concept of a local“recovery polynomial basis”–smooth polynomials that are in the weak sense indistinguishable from the discontinuous basis polynomials–and show it allows us to eliminate the recovery *** recovery method reproduces the symmetric discontinuous Galerkin formulation with additional penalty-like terms depending on the targeted accuracy of the *** present the unique link between the recovery method and discontinuous Galerkin bilinear forms.

关键词： Diffusion equation discontinuous Galerkin methods recovery basis L_(2)projection

New strategy for searching disturbance vector of SHA-1 collision attack

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Science China(Information Sciences) 2017年第12期60卷 280-282页

作者： Hao FenG Guang ZenG Wenbao HAN Yang YANG State Key Laboratory of Mathematical engineering and Advanced Computing centrum wiskunde & informatica Amsterdam 1098 XG Zhengzhou Information Science and Technology Institute Trusted Computing and Information Assurance Laboratory Institute of SoftwareChinese Academy of Sciences

Dear editor,We present a new algorithm to search for effective disturbance vectors with a complexity of 2;based on the following two properties of disturbance *** property is the weight correlation between the first 16-step disturbance vectors and the60-step disturbance *** other property requires all the differences of the active bit positions of the first 16-step disturbance vectors to be

关键词： New strategy for searching disturbance vector of SHA-1 collision attack

Bayesian Model Calibration with Interpolating Polynomials based on Adaptively Weighted Leja Node

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Communications in Computational Physics 2020年第1期27卷 33-69页

作者： Laurent van den Bos Benjamin Sanderse Wim Bierbooms Gerard van Bussel centrum wiskunde&informatica P.O.Box 940791090 GBAmsterdamThe Netherlands Delft University of Technology P.O.Box 52600 AADelftThe Netherlands

An efficient algorithm is proposed for Bayesian model calibration,which is commonly used to estimate the model parameters of non-linear,computationally expensive models using measurement *** approach is based on Bayesian statistics:using a prior distribution and a likelihood,the posterior distribution is obtained through application of Bayes’*** novel algorithm to accurately determine this posterior requires significantly fewer discrete model evaluations than traditional Monte Carlo *** key idea is to replace the expensive model by an interpolating surrogate model and to construct the interpolating nodal set maximizing the accuracy of the *** determine such a nodal set an extension to weighted Leja nodes is introduced,based on a new weighting *** prove that the convergence of the posterior has the same rate as the convergence of the *** the convergence of the posterior is measured in the Kullback–Leibler divergence,the rate *** algorithm and its theoretical properties are verified in three different test cases:analytical cases that confirm the correctness of the theoretical findings,Burgers’equation to show its applicability in implicit problems,and finally the calibration of the closure parameters of a turbulence model to show the effectiveness for computa-tionally expensive problems.

关键词： Bayesian model calibration interpolation Leja nodes surrogate modeling

A Projected Algebraic Multigrid Method for Linear Complementarity Problems

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Numerical Mathematics(Theory,Methods and Applications) 2012年第1期5卷 85-98页

作者： Jari Toivanen Cornelis W.Oosterlee Institute for Computational and Mathematical engineering Durand Buildingroom 023AStanford UniversityStanfordCA 94305USA and Department of Mathematical Information TechnologyAgoraFI-40014 University of JyväskyläFinland centrum voor wiskunde en informatica ModellingAnalysis and Simulation(MAS2)Kruislaan 413AmsterdamThe Netherlands and Delft University of TechnologyDelft Institute of Applied MathematicsMekelweg 42628 CD DelftThe Netherlands

We present an algebraic version of an iterative multigrid method for obstacle problems,called projected algebraic multigrid(PAMG)*** show that classical algebraic multigrid algorithms can easily be extended to deal with this kind of *** paves the way for efficient multigrid solution of obstacle problems with partial differential equations arising,for example,in financial engineering.

关键词： Linear complementarity problem algebraic multigrid American options elasto-plastic torsion problem

LIPS-200离子推力器放电室原初电子动力学行为的数值模拟研究

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推进技术 2015年第1期36卷 155-160页

作者：陈娟娟张天平刘明正贾艳辉孙安邦兰州空间技术物理研究所甘肃兰州730000 centrum wiskunde & informatica 1090 GB Amsterdam

为了得到试验测量不到的气体放电过程中电磁场作用下单个原初电子的动力学行为，建立了LIPS-200离子推力器放电室二维仿真模型，应用网格粒子法（PIC）和蒙特卡洛碰撞（MCC）模拟法对其进行了研究。模拟得到在额定工况下原初电子和中性... 详细信息

为了得到试验测量不到的气体放电过程中电磁场作用下单个原初电子的动力学行为，建立了LIPS-200离子推力器放电室二维仿真模型，应用网格粒子法（PIC）和蒙特卡洛碰撞（MCC）模拟法对其进行了研究。模拟得到在额定工况下原初电子和中性原子之间的碰撞概率、原初电子损耗率、电磁场分布对其运动速度及运动轨迹的影响等。结果表明磁铁表面磁感强度最大，越靠近放电室内部磁感强度越小，对称轴区域无磁场分布，原初电子在电磁场作用下沿磁力线作加速螺旋运动；运动等离子体的自洽电势大小范围仅为0~2.0V，几乎不会影响等离子体运动；对应总原初电子个数为1.2×106时直接被阳极表面吸收的损耗率仅为0.02%。

关键词： LIPS-200 离子推力器放电室原初电子 PIC/MCC数值模拟

ON THE VALIDITY OF THE LOCAL FOURIER ANALYSIS

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Journal of Computational Mathematics 2019年第3期37卷 340-348页

作者： Carmen Rodrigo Francisco J.Gaspar Ludmil T.Zikatanov Departamento de Matematica Aplicada IUMAUniversidad de ZaragozaZaragozaSpain CWI Centrum Wiskunde & InformaticaScience Park 1231090 AmsterdamThe Netherlands Department of Mathematics The Pennsylvania State UniversityUniversity ParkPennsylvania 16802USAInstitute for Mathematics and InformaticsBulgarian Academy of SciencesSofia.Bulgaria

Local Fourier analysis(LFA)is a useful tool in predicting the convergence factors of geometric multigrid methods(GMG).As is well known,on rectangular domains with periodic boundary conditions this analysis gives the exact convergence factors of such met *** other boundary conditions are considered,however,this analysis was judged as been heuristic,with limited capabilities in predicting multigrid convergence *** this work,using the Fourier method,we extend these results by proving that such analysis yields the exact convergence factors for a wider class of problems,some of which can not be handled by the traditional rigorous Fourier analysis.

关键词： Local Fourier analysis Multigrid Fourier method

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贝叶斯因子及其在JASP中的实现

心理科学进展 2018年第6期26卷 951-965页

作者：胡传鹏孔祥祯 Eric-Jan Wagenmakers Alexander Ly 彭凯平清华大学心理学系北京100084 Neuroimaging Center Johannes Gutenberg University Medical Center55131 MainzGermany Language and Genetics Department Max Planck Institute for Psycholinguistics6500 AH NijmegenThe Netherlands Department of Psychological Methods University of Amsterdam1018 VZ AmsterdamThe Netherlands centrum wiskunde&informatica 1090 GB AmsterdamThe Netherlands

统计推断在科学研究中起到关键作用,然而当前科研中最常用的经典统计方法——零假设检验(Null hypothesis significance test,NHST)却因难以理解而被部分研究者误用或滥用。有研究者提出使用贝叶斯因子(Bayes factor)作为一种替代和(或... 详细信息

统计推断在科学研究中起到关键作用,然而当前科研中最常用的经典统计方法——零假设检验(Null hypothesis significance test,NHST)却因难以理解而被部分研究者误用或滥用。有研究者提出使用贝叶斯因子(Bayes factor)作为一种替代和(或)补充的统计方法。贝叶斯因子是贝叶斯统计中用来进行模型比较和假设检验的重要方法,其可以解读为对零假设H_0或者备择假设H_1的支持程度。其与NHST相比有如下优势:同时考虑H_0和H_1并可以用来支持H_0、不"严重"地倾向于反对H_0、可以监控证据强度的变化以及不受抽样计划的影响。目前,贝叶斯因子能够很便捷地通过开放的统计软件JASP实现,本文以贝叶斯t检验进行示范。贝叶斯因子的使用对心理学研究者来说具有重要的意义,但使用时需要注意先验分布选择的合理性以及保持数据分析过程的透明与公开。

关键词：贝叶斯因子贝叶斯学派频率学派假设检验 JASP

An Investigation of Optimal Machine Learning Methods for the Prediction of ROTI

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Journal of Geodesy and Geoinformation Science 2020年第2期3卷 1-15页

作者： Fulong XU Zishen LI Kefei ZHANG Ningbo WANG Suqin WU Andong HU Lucas Holden School of environment Science and Spatial Information China University of Mining and TechnologyXuzhou 221116China Satellite Positioning for Atmosphere Climate and Environment(SPACE)Research CentreRoyal Melbourne Institute of Technology(RMIT)UniversityMelbourne VIC 3001Australia Aerospace Information Research Institute Chinese Academy of SciencesBeijing 10094China centrum wiskunde&informatica(CWI) P.O.Box 940791090 GB Amsterdam NETHERLANDS

The rate of the total electron content(TEC)change index(ROTI)can be regarded as an effective indicator of the level of ionospheric scintillation,in particular in low and high latitude *** accurate prediction of the ROTI is essential to reduce the impact of the ionospheric scintillation on earth observation systems,such as the global navigation satellite ***,it is difficult to predict the ROTI with high accuracy because of the complexity of the *** this study,advanced machine learning methods have been investigated for ROTI prediction over a station at high-latitude in *** methods are used to predict the ROTI in the next 5 minutes using the data derived from the past 15 minutes at the same *** results show that the method of the bidirectional gated recurrent unit network(BGRU)outperforms the other six approaches tested in the *** is also confirmed that the RMSEs of the predicted ROTI using the BGRU method in all four seasons of 2017 are less than 0.05 TECU/*** is demonstrated that the BGRU method exhibits a high level of robustness in dealing with abrupt solar activities.

关键词： machine learning ROTI prediction ionospheric scintillation high-latitude region

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贝叶斯方差分析在JASP中的实现

心理技术与应用 2023年第9期11卷 528-541页

作者：王允宏 Don van den Bergh Frederik Aust Alexander Ly Eric-Jan Wagenmakers 胡传鹏上海师范大学心理学系上海200234 Department of Psychological Methods University of Amsterdam1018 VZ AmsterdamThe Netherlands centrum wiskunde&informatica 1090 GB AmsterdamThe Netherlands 南京师范大学心理学院南京210024

贝叶斯统计应用于假设检验的方法——贝叶斯因子——在心理学研究中的应用日渐增加。贝叶斯因子能分别量化所支持的相应假设或模型的证据,进而根据其数值大小做出当前数据更支持哪种假设或模型的判断。然而,国内尚缺乏对方差分析的贝叶... 详细信息

贝叶斯统计应用于假设检验的方法——贝叶斯因子——在心理学研究中的应用日渐增加。贝叶斯因子能分别量化所支持的相应假设或模型的证据,进而根据其数值大小做出当前数据更支持哪种假设或模型的判断。然而,国内尚缺乏对方差分析的贝叶斯因子的原理与应用的介绍。基于此,本文首先介绍贝叶斯方差分析的基本思路及计算原理,并结合实例数据,展示如何在JASP中对五种常用的心理学实验设计(单因素组间设计、单因素组内设计、二因素组间设计、二因素组内设计和二因素混合设计)进行贝叶斯方差分析及如何汇报和解读结果。贝叶斯方差分析提供了一个能有效替代传统方差分析的方案,是研究者进行统计推断的有力工具。

关键词：贝叶斯统计贝叶斯因子方差分析 JASP