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Comprehensive Euler/Lagrange modelling including particle erosion for confined gas-solid flows

Particuology 2024年第1期84卷 209-235页

作者： Guiherme A.Novelletto Ricardo martin Sommerfeld Multiphase Flow Systems Institute of Process EngineeringOtto-von-Guericke-University MagdeburgHoher Weg 7b06120Halle(Saale)Germany

The present research aims to assess the capability of a comprehensive Euler/Lagrange approach for predicting gas-solid flows and the associated solid particle *** open-source code OpenFOAM®4.1 was used to carry out the numerical simulations,where the standard Lagrangian libraries were substantially extended to account for all necessary *** are tracked considering both translational and rotational motion as well as all relevant forces,such as gravity/buoyancy,drag and transverse lift due to shear and particle *** tracking time step was dynamically adapted ac-cording to the locally relevant time scales,which drastically reduces computational *** approaches are adopted to model particle turbulent dispersion,particle collisions with rough walls and particle-particle *** solid particle erosion models,available in the literature,were considered to estimate pipe bend *** study cases are provided to validate the adopted nu-merical approach and erosion models *** first case intends to evaluate the ability of the extended CFD code to predict the behaviour of gas-solid flows in pneumatic conveying *** goal is achieved by comparing the numerical results with the experimental data obtained by Huber(1997)and Huber and Sommerfeld(1994,1998)in a pneumatic conveying ***,the importance of considering inter-particle collisions and surface roughness for predicting particle velocity,mass flux and mean diameter distributions in gas-solid flows is *** second and third case intend to evaluate the ability of the erosion models in estimating bend erosion in diluted gas-solid *** erosion data obtained experimentally by Mazumder et al.(2008)and Solnordal et al.(2015)in very dilut pneumatic conveying systems is used for validating the numerical results,neglecting now inter-particle collisions and two-way *** a comprehensive analysis of the different influential properti

关键词： Pneumatic conveying Pipe bend Numerical calculation(CFD) Euler/Lagrange approach Erosion models Wall roughness

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Coal mine roof rating(CMRR),rock mass rating(RMR)and strata control:Carborough Downs Mine,bowen basin,Australia

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International Journal of Mining Science and Technology 2020年第2期30卷 225-234页

作者： martin brook bruce Hebblewhite Rudrajit Mitra School of Environment University of AucklandAuckland 1010New Zealand School of Mining Engineering University of New South WalesNSW 2052Australia School of Mining Engineering University of the WitwatersrandJohannesburg 2050South Africa

The rock mass rating(RMR)has been used across the geotechnical industry for half a *** contrast,the coal mine roof rating(CMRR)was specifically introduced to underground coal mines two decades ago to link geological characterization with geotechnical risk *** premise of CMRR is that strength properties of mine roof rock are influenced by defects typical of coal measures *** CMRR has been used in longwall pillar design,roof support methods,and evaluation of extended cuts,but is rarely ***,the RMR and CMRR are applied to a longwall coal *** rock mass classifications were undertaken at 67 locations across the *** classifications showed marked spatial variability in terms of roof *** and reverse faulting occur across the mine,and while no clear relationships exist between rock mass character and faulting,a central graben zone showed heterogeneous rock mass properties,and divergence between CMRR and ***,the CMRR data fell within the broad envelope of results reported for extended cuts at Australian and *** *** corollary is that the CMRR is useful,and should not be used in isolation,but rather as a component of a strata control programme.

关键词： Rock mass classification Roof strength Coal mine CMRR RMR bowen basin

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THAI experimental research on hydrogen risk and source term related safety systems

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Frontiers in Energy 2021年第4期15卷 887-915页

作者： Sanjeev GUPTA martin FREITAG Gerhard POSS becker Technologies GmbH Rahmannstrasse 11Eschborn 65760Germany

In the defense-in-depth concept employed for the safety of nuclear installations,maintaining integrity of containment as the last barrier is of high importance to limit the release of radioactivity to the environment in case of a severe *** active and passive safety systems implemented in containments of light water reactors(LWRs)are designed to limit the consequences of such *** the performance and reliability of such systems under accident conditions is critical to the safety of nuclear *** the aftermath of the Fukushima accident,there has been focus on re-examining the existing safety systems to demonstrate their capabilities for a broader range of boundary conditions comprising both the early as well as the late phases of an *** addition to the performance testing of safety systems,their interaction with containment atmosphere needs detailed investigations to evaluate the effects of operation of safety systems on H2 risk and fission product(FP)behavior in containment,which may ultimately have an impact on the source term to the *** this context,an extensive containment safety related experimental research has been conducted in a thermalhydraulics,hydrogen,aerosols,and iodine test facility(THAI,60 m3,single vessel)/(THAI+,80 m3,two interconnected vessels).Related to the subject of this paper,experimental investigations covered performance testing of various safety and mitigation systems,i.e.,containment spray,passive autocatalytic recombiner(PAR),pressure suppression pool(water pools),and effects of their operation on H2 risk and in-containment FP *** experimental results have provided a better phenomenological understanding and database for validation and further improvement of a safety analysis tool based on computation fluid dynamic(CFD)and lumped parameter(LP)modeling *** paper summarizes the main insights obtained from the aforesaid THAI experimental research covering safety systems

关键词： severe accident containment safety mitigation H2 risk source term

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The Sandfish's Skin:Morphology,Chemistry and Reconstruction

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Journal of bionic Engineering 2007年第1期4卷 1-9页

作者： Werner baumgartner Friederike Saxe Agnes Weth David Hajas Darwin Sigumonrong Jens Emmerlich martin Singheiser Wolfgang bhme Jochen M. Schneider Department of Cellular Neurobionics RWTH-Aachen Kopernikusstr. 16 52056 Aachen Germany Material Chemistry RWTH-Aachen Kopernikusstr. 16 52056 Aachen Germany Institute of Zoology RWTH-Aachen Kopernikusstr. 16 52056 Aachen Germany Zoologisches Forschungsmuseum Alexander Koenig (ZFMK) Adenauerallee 160 53113 Bonn Germany

The sandfish is a lizard having the remarkable ability to move in desert sand in a swimming-like fashion. The most outstanding adaptations to this mode of life are the low friction behaviour and the extensive abrasion resistance of the sandfish skin against sand, outperforming even steel. We investigated the topography, the composition and the mechanical properties of sandfish scales. These consist of glycosylated keratins with high amount of sulphur but no hard inorganic material, such as silicates or lime. Remarkably, atomic force microscopy shows an almost complete absence of attractive forces between the scale surface and a silicon tip, suggesting that this is responsible for the unusual tribological properties. The unusual glycosylation of the keratins was found to be absolutely necessary for the described phenomenon. The scales were dissolved and reconstituted on a polymer surface resulting in properties similar to the original scale. Thus, we provide a pathway towards exploitation of the reconstituted scale material for future engineering applications.

关键词： Sandfish Skink Scincus scincus tribology nanoindentation keratin abrasion

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Leaf-inhabiting endophytic fungi of European beech (Fagus sylvatica L.) co-occur in leaf litter but are rare on decaying wood of the same host

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Fungal Diversity 2013年第3期60卷 43-54页

作者： martin Unterseher Derek Peršoh martin Schnittler Institute of botany and Landscape Ecology Ernst-Moritz-Arndt University GreifswaldGrimmer Str.8817487 GreifswaldGermany Department Mykologie University BayreuthUniversitätsstr.3095440 BayreuthGermany

Many microfungi are able to live in living plant *** contrast to plant pathogens and parasites the socalled endophytic fungi do not cause obvious disease symptoms in their ***,they constitute an ubiquitous active component in direct and multitrophic *** present study was conducted to assess the level of overlap of cultivable microfungi in living and decaying tissues of European beech(Fagus sylvatica L.)from a forest stand in North-Eastern *** focus lay on the hypothesized fall-spring relationship of leaf-inhabiting forest endophytes,which means that endophytes from autumn leaves persist as saprobes in litter or dead wood,sporulate and re-invade living leaves in *** cultures were isolated from living leaves,leaf litter and dead wood still attached to the tree by dilution-to-extinction cultivation in the years 2007–*** of species identity,species richness and species composition were based on microscopic identification and of sequencing the fungal DNA‘barcode’ITS(internal transcribed spacer).Species richness of litter-inhabiting microfungi equaled that of wood-inhabiting fungi and exceeded that of leaf *** most distinctive species assemblage was observed on wood,fungal species composition in living leaves and leaf litter were also significantly different from each *** the other hand a considerable compositional and phylogenetic overlap between leaf and litter fungi was revealed with phylogenetics,cluster analysis and non-metric multidimensional *** taxa accounting most to the similarity between living and decaying leaves belonged to Capnodiales,Xylariales,Diaporthales and ***,data from cultivated leaf-inhabiting beech endophytes were compared with a fungal 454 sequence data set from beech *** analysis allowed the partition of species lists into active fungal endophytes,fungal“epiphytes”and dormant fungal propagules.

关键词： Substrate turnover Community composition Fungal diversity Fungal life cycle Dilution-to-extinction cultivation

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Virtual Reality As a New Tool in the City Planning Process

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Tsinghua Science and Technology 2008年第S1期13卷 255-260页

作者： Kaj Sunesson Carl martin Allwood Dan Paulin Ilona Heldal Mattias Roupé Mikael Johansson brje Westerdahl Chalmers University of Technology

The introduction of virtual reality (VR)-models in the city planning process will cause changes in the traditional roles of the involved parties. In order to better understand some of these changes, the events involving the use of VR-models in an architectural competition concerning rebuilding-proposals for the city library in a Swedish city were analyzed. The study shows that VR was introduced into the competition as an extra add-on and that the VR-presentation was experienced as useful by the jury. The transformation of the architects’ contributions into VR was experienced as problematic by the architects, partly because they lost full control over the presentation. In the future architects are likely to have to produce the VR-models for their proposals themselves. This may make it more difficult for smaller architectural firms to enter the market but their proposals will be more accessible to a wider group of stakeholders.

关键词： architecture architectural competition city planning construction planning VR-models

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Kamenev-type criteria for nonlinear damped dynamic equations

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Science China Mathematics 2015年第7期58卷 1445-1452页

作者： bOHNER martin LI TongXing Department of Mathematics and Statistics Missouri University of Science and Technology School of Mathematical Sciences University of Jinan Department of Mathematics Linyi University

We establish a new Kamenev-type theorem for a class of second-order nonlinear damped delay dynamic equations on a time scale by using the generalized Riccati transformation technique. The criterion obtained improves related contributions to the subject. An example is provided to illustrate assumptions in our theorem are less restrictive.

关键词： oscillation second-order dynamic equation nonlinear damped delay equation time scale

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Hybrid 2D–3D optical devices for integrated optics by direct laser writing

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Light(Science & Applications) 2014年第1期3卷 173-181页

作者： martin Schumann Tiemo buckmann Nico Gruhler martin Wegener Wolfram Pernice Institute of Applied Physics and DFG-Center for Functional Nanostructures(CFN) Karlsruhe Institute of Technology(KIT)76131 KarlsruheGermany Institute of Nanotechnology(INT) 76344 Eggenstein-LeopoldshafenGermany

Integrated optical chips have already been established for application in optical *** also offer interesting future perspectives for integrated quantum optics on a *** present,however,they are mostly fabricated using essentially planar fabrication approaches like electron-beam lithography or UV optical *** further design options would arise if one had complete fabrication freedom in regard to the third dimension normal to the chip without having to give up the virtues and the know-how of existing planar fabrication *** a step in this direction,we here use three-dimensional dip-in direct-laser-writing optical lithography to fabricate three-dimensional polymeric functional devices on pre-fabricated planar optical chips containing Si3N4 waveguides as well as grating couplers made by standard electron-beam *** first example is a polymeric dielectric rectangular-shaped waveguide which is connected to Si3N4 waveguides and that is adiabatically twisted along its axis to achieve geometrical rotation of linear polarization on the *** rotator’s broadband performance at around 1550 nm wavelength is verified by polarization-dependent grating *** polarization rotation on the optical chip cannot easily be achieved by other *** second example is a whispering-gallery-mode optical resonator connected to Si_(3)N_(4) waveguides on the chip via polymeric *** mechanically connecting the latter to the disk,we can control the coupling to the resonator and,at the same time,guarantee mechanical stability of the three-dimensional architecture on the chip.

关键词： direct laser writing integrated optics nanophotonic circuits polarization conversion

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Perturbation Theory for Solutions to Second Order Elliptic Operators with Complex Coefficients and the L^p Dirichlet Problem

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Acta Mathematica Sinica,English Series 2019年第6期35卷 749-770页

作者： martin DINDO? Jill PIPHER School of Mathematics The University of Edinburgh and Maxwell Institute of Mathematical Sciences Department of Mathematics Brown University

We establish a Dahlberg-type perturbation theorem for second order divergence form elliptic operators with complex coefficients. In our previous paper, we showed the following result: If L_0 = div A^0(x)? + b^0(x) · ? is a p-elliptic operator satisfying the assumptions of Theorem 1.1 then the LpDirichlet problem for the operator L_0 is solvable in the upper half-space Rn+. In this paper we prove that the Lpsolvability is stable under small perturbations of L_0. That is if L_1 is another divergence form elliptic operator with complex coefficients and the coefficients of the operators L_0 and L_1 are sufficiently close in the sense of Carleson measures, then the LpDirichlet problem for the operator L_1 is solvable for the same value of p. As a corollary we obtain a new result on Lpsolvability of the Dirichlet problem for operators of the form L = div A(x)? + b(x) · ? where the matrix A satisfies weaker Carleson condition(expressed in term of oscillation of coefficients). In particular the coefficients of A need no longer be differentiable and instead satisfy a Carleson condition that controls the oscillation of the matrix A over Whitney boxes. This result in the real case has been established by Dindoˇs,Petermichl and Pipher.

关键词： Complex coefficients elliptic PDEs perturbation theory boundary value problems

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3D mixed finite elements for curved,flat piezoelectric structures

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International Journal of Smart and Nano Materials 2019年第4期10卷 249-267页

作者： martin Meindlhumer Astrid Pechstein Institute of Technical Mechanics Johannes Kepler University LinzLinzAustria

The Tangential-Displacement Normal-Normal-Stress(TDNNS)method is a finite element method that was originally introduced for elastic solids and later extended to piezoelectric *** uses tangential components of the displacement and normal components of the normal stress vector as degrees of freedom for *** the electric field,the electric potential is *** TDNNS method has been shown to provide elements which do not suffer from shear *** thin structures(*** patch actuators)can be modeled *** and prismatic elements of arbitrary polynomial order are provided in the current *** show that these elements can be used to discretize curved,shelllike geometries by curved elements of high aspect *** order of geometry approximation can be chosen independently from the polynomial order of the shape *** present two examples of curved geometries,a circular patch actuator and a radially polarized piezoelectric *** results of the TDNNS method are compared to results gained in *** obtain good results for displacements and electric potential as well as for stresses,strains and electric field when using only one element in thickness direction.

关键词： Piezoelasticity mixed finite elements curved elements locking free

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