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Iterative Subregion Correction Preconditioners with Adaptive Tolerance for Problems with Geometrically Localized Stiffness

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Communications on Applied Mathematics and Computation 2024年第2期6卷 811-836页

作者： Michael Franco Per-Olof persson Will Pazner Department of Mathematics University of CaliforniaBerkeleyBerkeleyCA 94720-3840USA Fariborz Maseeh Department of Mathematics and Statistics Portland State UniversityPortlandOR 97201USA

We present a class of preconditioners for the linear systems resulting from a finite element or discontinuous Galerkin discretizations of advection-dominated *** preconditioners are designed to treat the case of geometrically localized stiffness,where the convergence rates of iterative methods are degraded in a localized subregion of the *** convergence may be caused by a number of factors,including the mesh size,anisotropy,highly variable coefficients,and more challenging *** approach taken in this work is to correct well-known preconditioners such as the block Jacobi and the block incomplete LU(ILU)with an adaptive inner subregion *** goal of these preconditioners is to reduce the number of costly global iterations by accelerating the convergence in the stiff region by iterating on the less expensive reduced *** tolerance for the inner iteration is adaptively chosen to minimize subregion-local work while guaranteeing global convergence *** present analysis showing that the convergence of these preconditioners,even when combined with an adaptively selected tolerance,is independent of discretization parameters(e.g.,the mesh size and diffusion coefficient)in the *** demonstrate significant performance improvements over black-box preconditioners when applied to several model convection-diffusion ***,we present performance results of several variations of iterative subregion correction preconditioners applied to the Reynolds number 2.25×10^(6)fluid flow over the NACA 0012 airfoil,as well as massively separated flow at 30°angle of attack.

关键词： Subregion correction Nested Krylov Geometrically localized stiffness

Why ecosystem characteristics predicted from remotely sensed data are unbiased and biased at the same time-and how this affects applications

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Forest Ecosystems 2024年第1期11卷 24-31页

作者： Goran Ståhl Terje Gobakken Svetlana Saarela Henrik J.persson magnus Ekstrom Sean P.Healey Zhiqiang Yang Johan Holmgren Eva Lindberg Kenneth Nystrom Emanuele Papucci Patrik Ulvdal Hans OleØrka Erik Næsset Zhengyang Hou Håkan Olsson Ronald E.McRoberts Department of Forest Resource Management Swedish University of Agricultural Sciences90183UmeåSweden Faculty of Environmental Sciences and Natural Resource Management Norwegian University of Life SciencesÅsNorway USDA Forest Service Rocky Mountain Research StationOgdenUTUSA The Key Laboratory for Silviculture and Conservation of Ministry of Education Beijing Forestry UniversityBeijing100083China Department of Forest Resources University of MinnesotaSt.PaulMNUSA

Remotely sensed data are frequently used for predicting and mapping ecosystem characteristics,and spatially explicit wall-to-wall information is sometimes proposed as the best possible source of information for ***,wall-to-wall information typically relies on model-based prediction,and several features of model-based prediction should be understood before extensively relying on this type of *** such feature is that model-based predictors can be considered both unbiased and biased at the same time,which has important implications in several areas of *** this discussion paper,we first describe the conventional model-unbiasedness paradigm that underpins most prediction techniques using remotely sensed(or other)auxiliary *** this point of view,model-based predictors are typically ***,we show that for specific domains,identified based on their true values,the same model-based predictors can be considered biased,and sometimes severely *** suggest distinguishing between conventional model-bias,defined in the statistical literature as the difference between the expected value of a predictor and the expected value of the quantity being predicted,and design-bias of model-based estimators,defined as the difference between the expected value of a model-based estimator and the true value of the quantity being *** show that model-based estimators(or predictors)are typically design-biased,and that there is a trend in the design-bias from overestimating small true values to underestimating large true ***,we give examples of applications where this is important to acknowledge and to potentially make adjustments to correct for the design-bias *** argue that relying entirely on conventional model-unbiasedness may lead to mistakes in several areas of application that use predictions from remotely sensed data.

关键词： Bias Model-based inference Design-based inference

Cellulose synthesis in land plants

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Molecular Plant 2024年第2期17卷 359-361页

作者： Gustav B.Pedersen Leonard Blaschek Kristian E.H.Frandsen Lise C.Noack Staffan persson 不详

After the original publication of the above article,we and/or attentive readers identified several instances of unclear or erroneous writing that needed correcting,as *** are added for emphasis.

关键词： synthesis instance identif

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Rubber–ice friction

Friction 2023年第8期11卷 1534-1543页

作者： Toshi TADA Satoshi KAWASAKI Ryouske SHIMIZU Bo N.J.persson Sumitomo Rubber Industries Ltd.Material Research&Development HQ.2-1-1Kobe 651-0071Japan Peter Grünberg Institute(PGI-1) Forschungszentrum JülichJülich 52425Germany MultiscaleConsulting Jülich 52428Germany

We study the friction when a rectangular tire tread rubber block is sliding on an ice surface at different temperatures ranging from−38 to−2℃,and sliding speeds ranging from 3μm/s to 1 cm/*** low temperatures and low sliding speeds we propose that an important contribution to the friction force is due to slip between the ice surface and ice fragments attached to the rubber *** temperatures above−10℃ or for high enough sliding speeds,a thin premelted water film occurs on the ice surface and the contribution to the friction from shearing the area of real contact is *** this case the dominant contribution to the friction force comes from viscoelastic deformations of the rubber by the ice *** comment on the role of waxing on the friction between skis and snow(ice particles).

关键词： ice friction rubber friction ice premelting

Colorless-to-colorful switching of electrochromic MXene by reversible ion insertion

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Nano Research 2022年第4期15卷 3587-3593页

作者： Jianxia Jiang Leiqiang Qin Joseph Halim Per O.Å.persson Lintao Hou Johanna Rosen Guangzhou Key Laboratory of Vacuum Coating Technologies and New Energy Materials Physics DepartmentJinan UniversityGuangzhou 510632China Department of Physics Chemistry and Biology(IFM)Linköping UniversityLinköping SE-58183Sweden

Electrochromic(EC)materials that change color with voltage have been widely studied for use in dynamic ***,colorless-to-colorful switching with high contrast ratio is generically unattainable,especially for colorless-to-black electrochromic materials with an ultrahigh contrast ratio over the entire visible *** this work,we developed Nb_(1.33)C MXene-based dynamic windows with colorless-to-black switching of up to 75%reversible change in transmittance from 300 to 1,500 *** exploring the electrochromic effects of different electrolytes through in situ optical changes and electrochemical quartz crystal microbalance(EQCM),it is found that electrochromic behavior is greatly influenced by the extent of reversible Li^(+)insertion/deinsertion between the two-dimensional Nb_(1.33)C MXene *** addition,a colorless-to-black EC device based on Nb_(1.33)C with an overall integrated contrast ratio over 80%was successfully constructed by a solution-processable spin coating *** work enables a simple route to fabricate MXene-based high-performance electrochromic smart windows,which is important for further expanding the application of MXenes to optoelectronic and photonic applications.

关键词： MXenes electrochromic materials colorless-to-black switching high contrast ratio reversible Li^(+)insertion

Topological graph-based analysis of solid-state ion migration

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npj Computational Materials 2023年第1期9卷 1337-1341页

作者： Jimmy-Xuan Shen Haoming Howard Li Ann Rutt Matthew K.Horton Kristin A.persson Materials Science Division Lawrence Livermore National LaboratoryLivermoreCAUSA Materials Sciences Division Lawrence Berkeley National LaboratoryBerkeleyUSA Department of Material Science and Engineering University of CaliforniaBerkeleyCAUSA Molecular Foundry Lawrence Berkeley National LaboratoryBerkeleyUSA

To accelerate the development of ion conducting materials,we present a general graph-theoretic analysis framework for ion migration in any crystalline *** nodes of the graph represent metastable sites of the migrating ion and the edges represent discrete migration events between adjacent *** from a collection of possible metastable migration sites,the framework assigns a weight to the edges by calculating the individual migration energy barriers between those *** pathways in the periodic simulation cell corresponding to macroscopic ion migration are identified by searching for the lowest-cost cycle in the periodic migration *** exemplify the utility of the framework,we present the automatic analyses of Li migration in different polymorphs of VO(PO_(4)),with the resulting identification of two distinct crystal structures with simple migration pathways demonstrating overall<300 meV migration barriers.

关键词： analysis migration metastable

MXene-based symmetric supercapacitors with high voltage and high energy density

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Materials Reports(Energy) 2022年第1期2卷 105-111页

作者： Wei Zheng Joseph Halim Per O.Å.persson Johanna Rosen Michel W.Barsoum Department of Physics Chemistry and Biology(IFM)Linkoping University58183LinkopingSweden Department of Materials Science and Engineering Drexel University19104PhiladelphiaPAUSA

MXene-based aqueous symmetric supercapacitors(SSCs)are attractive due to their good rate performances and green ***,it remains a challenge to reach voltages much over 1.2 V,which significantly diminishes their energy ***,we report on Mo_(1.33)CTz MXene-based SSCs possessing high voltages in a 19.5 M LiCl *** from the vacancy-rich structure and high stable potential window of Mo_(1.33)CTz,the obtained SSCs deliver a maximum energy density of>38.2 mWh cm^(-3) at a power density of 196.6 mW cm^(-3) under an operating voltage of 1.4 V,along with excellent rate performance and impressive cycling *** highly concentrated LiCl electrolyte is also applicable to Ti_(3)C_(2)Tz,the most widely studied MXene,achieving a maximum energy density of>41.3 mWh cm^(-3) at a power density of 165.2 mW cm^(-3) with an operating voltage of 1.8 *** drop in energy density with increasing power in the Ti_(3)C_(2)Tz cells was steeper than for the Mo-based *** work provides a roadmap to develop superior SSCs with high voltages and high energy densities.

关键词： MXene Symmetric supercapacitor High voltage High energy density Highly concentrated electrolyte

Cellulose Synthases and Synthesis in Arabidopsis

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Molecular Plant 2011年第2期4卷 199-211页

作者： Anne Endler Staffan persson Max-Planck-Institute for Molecular Plant Physiology Am M6hlenberg 1 14476 Potsdam Germany

Plant cell walls are complex structures composed of high-molecular-weight polysaccharides, proteins, and lignins. Among the wall polysaccharides, cellulose, a hydrogen-bonded β-1,4-1inked glucan microfibril, is the main load-bearing wall component and a key precursor for industrial applications. Cellulose is synthesized by large multi-meric cellulose synthase （CesA） complexes, tracking along cortical microtubules at the plasma membrane. The only known components of these complexes are the cellulose synthase proteins. Recent studies have identified tentative interaction partners for the CesAs and shown that the migratory patterns of the CesA complexes depend on phosphorylation status. These advances may become good platforms for expanding our knowledge about cellulose synthesis in the near future. In addition, our current understanding of cellulose chain polymerization in the context of the CesA complex is discussed.

关键词： Cell expansion cell walls cytoskeleton-cell wall interactions Arabidopsis.

An Update on Xylan Synthesis

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Molecular Plant 2012年第4期5卷 769-771页

作者： Anett Doering Rahul Lathe Staffan persson Max-Planck-Institute for Molecular Plant Physiology Am Muehlenberg 1 14476 Potsdam Germany

Plant cell walls are complex structural frameworks that affect cell shape and differentiation, and that protect the plant cell against environmental conditions （Scheller and Ulvskov, 2010）. One of the major componen... 详细信息

关键词： GLYCOSYL TRANSFERASES BIOSYNTHESIS GENES PROTEINS MEMBERS IRX15 GT43