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Implementation of 2D DomainDecomposition in the UCAN Gyrokinetic Particle-in-Cell Code and Resulting Performance of UCAN2

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Communications in Computational Physics 2016年第1期19卷 205-225页

作者： Jean-Noel G.Leboeuf viktor k.decyk David E.Newman Raul Sanchez Department of Physics University of AlaskaFairbanksAK 99775-5920USA Department of Physics and Astronomy and Institute for Digital Research and Education(IDRE)University of CaliforniaLos AngelesCA 90095-1547USA Departamento de Fsica Universidad Carlos IIILeganes 28911MadridSpain

The massively parallel,nonlinear,three-dimensional(3D),toroidal,electrostatic,gyrokinetic,particle-in-cell(PIC),Cartesian geometry UCANcode,with particle ions and adiabatic electrons,has been successfully exercised to identify non-diffusive transport characteristics in present day tokamak *** limitation in applying UCAN to larger scale discharges is the 1D domain decomposition in the toroidal(or z-)direction for massively parallel implementation using MPI which has restricted the calculations to a few hundred ion Larmor radii or gyroradii per plasma minor *** exceed these sizes,we have implemented 2D domain decomposition in UCANwith the addition of the y-direction to the processor *** has been facilitated by use of relevant components in the P2LIB library of field and particle management routines developed for UCLA’s UPIC Framework of conventional PIC *** gyroaveraging specific to gyrokinetic codes is simplified by the use of replicated arrays for efficient charge accumulation and force *** 2D domain-decomposed UCAN2 code reproduces the original 1D domain nonlinear results within *** of UCAN2 on the Cray XC30 Edison at NERSC demonstrate ideal scaling when problem size is increased along with processor number up to the largest power of 2 available,namely 131,072 *** particle weak scaling benchmarks also indicate that the 1 nanosecond per particle per time step and 1 TFlops barriers are easily broken by UCAN2 with 1 billion particles or more and 2000 or more processors.

关键词： Gyrokinetic simulation particle-in-cell method massive parall

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Jetting-based bioprinting:process,dispense physics,and applications

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Bio-Design and Manufacturing 2024年第5期7卷 771-799页

作者： Wei Long Ng viktor Shkolnikov Singapore Centre for 3D Printing(SC3DP) School of Mechanical and Aerospace EngineeringNanyang Technological University(NTU)Singapore 639798Singapore HP Inc. Palo AltoCA 94304USA

Jetting-based bioprinting facilitates contactless drop-on-demand deposition of subnanoliter droplets at well-defined positions to control the spatial arrangement of cells,growth factors,drugs,and biomaterials in a highly automated layer-by-layer fabrication *** to its immense versatility,jetting-based bioprinting has been used for various applications,including tissue engineering and regenerative medicine,wound healing,and drug development.A lack of in-depth understanding exists in the processes that occur during jetting-based *** review paper will comprehensively discuss the physical considerations for bioinks and printing conditions used in jetting-based *** first present an overview of different jetting-based bioprinting techniques such as inkjet bioprinting,laser-induced forward transfer bioprinting,electrohydrodynamic jet bioprinting,acoustic bioprinting and microvalve ***,we provide an in-depth discussion of various considerations for bioink formulation relating to cell deposition,print chamber design,droplet formation and droplet ***,we highlight recent accomplishments in jetting-based *** present the advantages and challenges of each method,discuss considerations relating to cell viability and protein stability,and conclude by providing insights into future directions of jetting-based bioprinting.

关键词： 3D bioprinting Biofabrication Jetting-based Dispense physics Machine learning

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Experimental study on influence of blade angle and particle size on particle mechanics on a batch-operated single floor of a multiple hearth furnace

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Particuology 2024年第2期85卷 224-240页

作者： Max kriegeskorte Nikoline Hilse Phil Spatz viktor Scherer Institute for Energy Plant Technology(LEAT) Ruhr University BochumUniversitätsstraβe 15044780 BochumGermany

In industry,multiple hearth furnaces are used for the thermal treatment of particulate *** current contribution concentrates on the experimental analysis of particle mechanics for a batch-operated single floor of a multiple hearth *** particles are agitated on the circular floor by a single,rotating rabble arm equipped with three flat rabble blades of 10 mm *** blade angle,defined as the angle,which the blade is inclined against the tangential direction,is varied from 0°to 90°.A single layer of spherical polyoxymethylene(POM)particles with three different diameters(5,10 and 20 mm)is placed on the *** analyze the results,two parameters have been extracted from image analysis when the bed of particles is agitated,first,the area not covered by particles and second,the frequency distribution of the mean distance among the *** particle free surface area increases with the inclination of the *** evolution of the particle free surface area differs for the different particle *** general,the maximum particle free area for all blade angles is the largest for the 5 mm particles followed by the 20 mm *** the 10 mm particles,the particle free surface area starts for a blade angle of 0°at larger values than for the 20 mm particles but the values fall below the values for the 20 mm particles for larger blade *** reason for this behavior is discussed in *** mean distance among the particles is a parameter characterizing the length scales dominating the effects on the *** frequency distribution of the mean distance among particles provides infor-mation about the morphology of the particle bulk,for example,whether the free surface area is inter-spersed with particles.

关键词： Hearth furnace floor Particle movement Spherical particles Particle free surface area Mean distance among particles

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Cardiovascular mechanisms of thyroid hormones and heart failure:Current knowledge and perspectives

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World Journal of Cardiology 2024年第5期16卷 226-230页

作者： viktor Culic Department of Cardiology and Angiology University Hospital Centre SplitUniversity of Split School of MedicineSplit 21000Croatia

A multiple hormonal imbalance that accompanies heart failure(HF)may have a significant impact on the clinical course in such *** non-thyroidal illness syndrome(NTIS),also referred to as euthyroid sick syndrome or low triiodothyronine syndrome,can be found in about 30%of patients with *** represents a systemic adaptation to chronic illness that is associated with increased cardiac and overall mortality in patients with *** conclusions on thyroid-stimulating hormone,free triiodothyronine,total and free thyroxine are currently unresolved,serum total triiodothyronine levels and the ratio of free triiodothyronine to free thyroxine seem to provide the best correlates to the echocardiographic,laboratory and clinical parameters of disease *** patients with either hyper-or hypothyroidism should be treated according to the appropriate guidelines,but the therapeutic approach to NTIS,with or without HF,is still a matter of *** treatment options include better individual titration of levothyroxine therapy,combined triiodothyronine plus thyroxine therapy and natural measures to increase *** research should further examine the cellular and tissue mechanisms of NTIS as well as new therapeutic avenues in patients with HF.

关键词： Heart failure Non-thyroidal illness syndrome Low triiodothyronine syndrome Therapy Thyroxine Triiodothyronine

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Is Veillonella a unique marker of physical exercise?Commentary on:

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Journal of Sport and Health Science 2024年第5期13卷 682-684页

作者： viktor Bielik Ivan Hric Riadh Hammami Department of Biological and Medical Science Faculty of Physical Education and SportComenius University in BratislavaBratislava 81469Slovakia Department of Molecular Biology Faculty of Natural SciencesComenius University in BratislavaBratislava 84215Slovakia Biomedical Research Center Institute of Clinical and Translational ResearchSlovak Academy of SciencesBratislava 84505Slovakia School of Nutrition Sciences Faculty of Health SciencesUniversity of OttawaOttawaON K1N 6N5Canada Department of Biochemistry Microbiology and ImmunologyFaculty of MedicineUniversity of OttawaOttawaON K1N 6N5Canada

In 2020,kostic1 published commentary on the bacterial genus Veillonella associated with the interaction between the intestinal microbiota and skeletal *** then,novel perspectives on the bidirectional gut-muscle communication axis have gained a lot of *** purpose of this commentary is to explore some of the challenging issues presented in Scheiman et al.

关键词： skeletal gained

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Investigating the inflow into a granular bed using a locally resolved method

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Particuology 2024年第2期85卷 89-101页

作者： Maximilian Brommer Maik Scharnowski Enric Illana Mahiques Siegmar Wirtz viktor Scherer Ruhr University Bochum Institute of Energy Plant TechnologyUniversitätsstraβe 15044780BochumGermany

Discrete Element Method-Computational Fluid Dynamics(DEM/CFD)simulations of industrial-scale granular systems employ spatial averaging(porous media approach)for the fluid-particle interaction in the whole domain,which can lead to poor accuracy,for instance at flow inlets,as local particle bulk morphology is not *** paper presents an approach where the interstitial flow in crucial areas with large gradients can be resolved locally in an otherwise unresolved domain,so that a mixed resolved-unresolved method is *** a generic example to show the feasibility and performance of the new approach,the inflow of ambient air into a flat-bottom hopper through a narrow orifice is *** an experimental setup,the vertical profile of the pressure decay through the inlet and across the packing is chosen for com-parison with respective *** obtained with the conventional porous media method and the locally resolved approach are compared to these experiments for varying volume flow rates and for two different particle *** of different size as well as dodecahedrons are *** is found that although averaging methods already provide good approximations,the locally resolved method can improve the result especially when conventional drag laws are not applicable due to wall effects or if large velocity gradients exist.

关键词： DEM/CFD Packed bed Pressure drop

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A reduced model for particle calcination for use in DEM/CFD simulations

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PARTICUOLOGY 2024年第10期93卷 316-327页

作者： Mieg, Lucas Bergold, Torben Mahiques, Enric Illana Scherer, viktor Moennigmann, Martin Ruhr Univ Bochum Automat Control & Syst Theory Bochum Germany Ruhr Univ Bochum Energy Plant Technol Bochum Germany

We treat the accurate simulation of the calcination reaction in particles, where the particles are large and, thus, the inner-particle processes must be resolved. Because these processes need to be described with coupled partial differential equations (PDEs) that must be solved numerically, the computation times for a single particle are too high for use in simulations that involve many particles. Simulations of this type arise when the Discrete Element Method (DEM) is combined with Computational Fluid Dynamics (CFD) to investigate industrial systems such as quicklime production in lime shaft kilns. We show that, based on proper orthogonal decomposition and Galerkin projection, reduced models can be derived for single particles that provide the same spatial and temporal resolution as the original PDE models at a considerably reduced computational cost. Replacing the finite volume particle models with the reduced models results in an overall reduction of the reactor simulation time by about 40% for the sample system treated here. (c) 2024 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY license (http:// ***/licenses/by/4.0/).

关键词： Calcination Reactive bulk Model reduction Discrete element method Galerkin projection SOLID HEAT-TRANSFER DEM-CFD SIMULATION MASS-TRANSFER WOOD CHIPS DECOMPOSITION COMBUSTION REDUCTION LIMESTONE DYNAMICS FLOW

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Shape-changing particles for locally resolved particle geometry in DEM simulations

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Particuology 2024年第6期89卷 185-190页

作者： Enric Illana klidi Qyteti Maik Scharnowski Maximilian Brömmer Siegmar Wirtz viktor Scherer Institute of Energy Plant Technology Ruhr-University BochumBochumGermany

Taking into account the complex shape of particles in discrete element method (DEM) simulations of large-scale granular systems is computationally demanding due to the time-consuming contact detection algorithms for polyhedral particles. In this short communication, a novel approach that locally resolves the particle shapes where needed and uses a simplified representation elsewhere, to accelerate simulations without compromising accuracy, is presented. For this purpose, a method employing a smooth transition of the particle shape representation from analytical spheres to shape-resolving polyhedra is introduced in DEM. The feasibility and correct implementation of this approach are demonstrated through simulations of hopper discharge involving spherical and dodecahedral particles from a flat bottom silo or shaft kiln. The model capabilities, in terms of accuracy as well as reduction in computational effort, are quantified for a moving bed with continuous outflow.

关键词： Polyhedron Size change Shape change Locally resolved DEM

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Age and geochemical evolution of granite magmatism in Olkhon region from Caledonian syncollisional ore-free granite to the rare metal granite and pegmatite of Middle Paleozoic intraplate setting

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China Geology 2024年第1期7卷 63-79页

作者： viktor Antipin Valentina Makrygina Larisa kushch Nataliya Sheptyakova Vinogradov Institute of Geochemistry SB RAS664033 IrkutskRussia

The detailed description of two granite complexes in the Olkhon subterrane is *** Early Paleozoic Sharanur complex was formed by granitization of gneisses of the Olkhon *** includes migmatites,granite-gneisses,granites and pegmatites of normal alkalinity;they belong to the type of syncollisional *** Middle Paleozoic Aya granite complex includes mother Aya massif of amazonite-bearing granites and several types of rare-metal *** have elevated alkalinity,low of Ba,Sr,and high LILE and HFSE elements *** Aya pegmatites lie in northwest cracks of stretching and associated with the rise of the territory under the influence of the North Asian *** cracks and pegmatites mark the beginning of a new intraplate geodynamic *** geochemical types are distinguished among the pegmatites of this *** are amazonite pegmatites of Li-F type with Ta mineralization and complex type pegmatite with Be-Rb-Nb-Ta and Li-F mineralization(the Ilixin vein).The Tashkiney pegmatite vein is similar to Ilixin,but lies in the gneisses of the Olkhon *** shows high concentrations of Be,Nb,Ta,as well as W,Sn,but lacks Li and F,due to a greater depth and higher temperature of the melt crystallization of this pegmatite.

关键词： Pegmatite Geochemistry Submantle plume Magmatism Caledonian collision Middle Paleozoic intraplate setting Be-Rb-Nb-Ta-Li-F mineralization Olkhon region Russia

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Convective drying of wood chips:Accelerating coupled DEM-CFD simulations with parametrized reduced single particle models

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Particuology 2024年第1期84卷 158-167页

作者： Lucas Reineking Jonas Fischer Ali Mjalled Enric Illana Siegmar Wirtz viktor Scherer Martin Monnigmann Automatic Control and System Theory Ruhr-Universität-BochumUniversitätstraße 150Bochum44801Germany Energy Plant Technology Ruhr-Universität-BochumUniversitätstraße 150Bochum44801Germany

The simulation of industry-scale reactive bulks is challenging due to the complex interaction between fluid and *** particles in the bulk and their interaction with the fluid flow can be described by combined Discrete Element Method-Computational Fluid Dynamics(DEM-CFD)***,the computational cost of the Finite Volume(FV)methods deployed in these models can become prohibi-tively expensive,especially for high inner-particle *** particle Reduced Models(RMs)can be used to achieve both fast and accurate descriptions of the processes in each *** an example of bulk systems comprising heat and mass transfer,we compared FV and RM simulations for the drying of wood chips in a bulk reactor.A manifold-based nonlinear interpolation was applied to resolve changing boundary conditions for the *** simulations showed that RMs provide accurate values for the thermodynamic state variables of the ***,the time required for the bulk simulation was reduced by 67%with the *** is evident that simulations with high inner-particle resolution can be accelerated by RMs if manifold-based nonlinear interpolation is used to address changing boundary conditions.

关键词： Reduced model Reactive bulk Discrete element method Manifold-based interpolation Drying of porous mediaDEM-CFD

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