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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

Human brain computing and brain-inspired intelligence

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National Science Review 2024年第5期11卷 8-9页

作者： Jianfeng Feng viktor Jirsa Wenlian Lu Institute of Science and Technology for Brain-Inspired Intelligence Fudan University Key Laboratory of Computational Neuroscience and Brain-Inspired Intelligence(Fudan University) Ministry of Education Shanghai Center for Mathematical Sciences Fudan University Department of Computer Science University of Warwick Zhangjiang Fudan International Innovation Center Institut de Neurosciences des Systèmes Faculté de Medécine

The relationship between structure, neural activity dynamics and intelligent human brain function is complex and multifaceted with deep roots in several academic disciplines. Its understanding is a fundamental goal of brain research [1] and may indicate the way towards the next generation of artificial intelligence [2]. There are major challenges on the way, several of which are addressed in this Special Topic of National Science Review.

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Magnetic methods in studies of new superconducting hydrides in a diamond anvil cell

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National Science Review 2024年第7期11卷 16-18页

作者： viktor V.Struzhkin Ho-kwang Mao Center for High Pressure Science&Technology Advanced Research

In recent years, we have witnessed great success in discoveries of high-transition-temperature（Tc） hydrides using high-pressure experiments. This has been achieved by creating metallic hydrogen‘alloys’ with other ...

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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

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

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： Lucas Mieg Torben Bergold Enric Illana Mahiques viktor Scherer Martin Mönnigmann Automatic Control and System Theory Ruhr University BochumGermany Energy Plant Technology Ruhr University BochumGermany

We treat the accurate simulation of the calcination reaction in particles,where the particles are large and,thus,the inner-particle processes must be *** 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 *** 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 *** 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 *** 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.

关键词： Calcination Reactive bulk Model reduction Discrete element method Galerkin projection

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

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