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Simulation of spray coating in a spouted bed using recurrence CFd

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Particuology 2019年第1期17卷 92-103页

作者： Paul Kieckhefena Thomas Lichtenegger Swantje Pietsch stefan Pirker stefan Heinrich Institute of Solids Process Engineering and Particle Technology Hamburg University of Technology. HamburgGermany department for Particulate Flow Modelling. Johannes Kepler University LinzAustria Linz Institute of Technology (LIT) Johannes Kepler UniversityLinzAustria

Although numerical models such as the computational fluid dynamics–discrete element method (CFd–dEM) have enabled the accurate simulation of laboratory-scale apparatuses, the application of these methods to large-scale apparatuses with many particles and time scales ranging from minutes to hours remains a challenge. The recently developed recurrence CFd (rCFd) method seeks to overcome these issues in pseudo-periodic processes by extrapolating globally recurring patterns in a physically meaningful way and describing the transport and interaction of passive scalars using Lagrangian tracers. Spouted beds represent an interesting target because of the associated variety of flow regimes. They can be effectively described by CFd–dEM on the time scale of tens of seconds, whereas industrially relevant processes typically take hours. In this contribution, we established the validity of applying the Lagrangian rCFd method to spouted beds by demonstrating the accurate reproduction of the particle residence time distribution in a fictitious spray zone. The deposition of spray droplets onto tracer particles was simulated for 1 h, and the particle surface coverage distribution was estimated using a statistical approach for both an unstabilized prismatic spouted bed and one stabilized by draft plates.

关键词： CFd–dEM Recurrence CFd Spray coating Time-scale decoupling Spouted bed draft plate

Product design based on discrete particle modeling of a fluidized bed granulator

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Particuology 2014年第1期12卷 13-24页

作者： Lennart Fries Sergiy Antonyuk stefan Heinrich Gerhard Niederreiter stefan Palzer Nestlé Research Center Institute of Solids Process Engineering and Particle Technology Hamburg University of Technology

Fluidized bed agglomeration is a process commonly used to construct powdered food or pharmaceuti cal products to improve their instant properties. This works analyzes the influence of a wide range of operating parameters （i.e., fluidization air flow rate, temperature, and liquid injection rate） on growth rate, process stability, and product particle structure. different granulator configurations （i.e., top spray, Wurster coater, spouted bed） are compared using identical process parameters. The impacts of both pro cess variables and granulator geometry on the fluidization regime, the particle and collision dynamics, and the resulting product structure and corresponding properties are studied in detailed simulations using a discrete particle model （dPM） and labscale agglomeration experiments with amorphous dextrose syrup （dE21）. The combination of numerical and experimental results allows to correlate the kinetics of micro scale particle interactions and the final product properties （i.e., agglomerate structure and strength）. In conclusion, detailed dPM simulations are proven as a valuable tool for knowledgebased product design.

关键词： FluidizationAgglomerationdiscrete element methodFood powderCollision dynamics

Quantum-gas microscopes:a new tool for cold-atom quantum simulators

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National Science Review 2016年第2期3卷 170-172页

作者： stefan Kuhr department of Physics University of Strathclyde

Imagine a new generation of computers that dramatically surpasses the most powerful supercomputers,being able to tackle the most challenging of computational *** problems arise,for example,in quantum physics where the... 详细信息

关键词： Quantum-gas microscopes body

Factors influencing the spinal motoneurons in development

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Neural Regeneration Research 2015年第11期10卷 1773-1776页

作者： stefan Wiese Faculty for Biology and Biotechnology Group for Molecular Cell Biology Universitaetsstr.150 Ruhr University Bochum

The development of the spinal cord needs a concerted interaction of transcription factors activating diverse genes and signals from outside acting on the specification of the different cells. Signals have to act on the segments of the embryo as well as on the cranial-caudal axis and the dorso-ventral axis. Additionally the axons of the motoneurons have to cross the central nervous system barrier to connect to the periphery. Intensive anatomical studies have been followed by molecular characterization of the different subsets of transcription factors that are expressed by cells of the developing spinal cord. Here, intensive studies for the most important appearing cells, the motoneurons, have resulted in a good knowledge on the expression patterns of these proteins. Nonetheless motoneurons are by far not the only important cells and the concert activity of all cells besides them is necessary for the correct function and integrity of motoneurons within the spinal cord. This article will briefly summarize the different aspects on spinal cord development and focuses on the differentiation as well as the functionalization of motoneurons.

关键词： axon neurite synapse muscle extracellular matrix transcription factors

Nanocrystalline rare earth fluorides doped with Pr^(3+) ions

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Journal of Rare Earths 2016年第8期34卷 802-807页

作者： Marcin Runowski stefan Lis department of Rare Earths Faculty of Chemistry Adam Mickiewicz University

Praseodymium（III） doped CeF3, CeF3：Gd, LaF3, GdF3 and YF3 inorganic fluorides were precipitated in an aqueous, sur- factant-free solution, using NH4F as a source of fluoride ions. The as-prepared products were subjected to a hydrothermal treatment, which led to the formation of crystalline nanoluminophores, composed of spherical （30 nm） and elongated （40-200 nm） nanos- tructures. due to the presence of Pr3＋ ions, the synthesized nanomaterials showed yellow luminescence under a blue light irradiation. The nanoluminophore based on the YF3 host revealed the most promising spectroscopic properties, i.e., bright and intensive emission, hence it was investigated in detail. The photophysical properties of the nanomaterials obtained were studied by powder X-ray diffrac- tion （XRd）, transmission electron microscopy （TEM） and spectrofluorometry, i.e., measurements of excitation/emission spectra and luminescence decay curves.

关键词： yellow luminescence lanthanide fluorides Pr3+ doping nanocrystals hydrothermal post-treatment Ce3+ quenching rare earths

Origin of non-uniform plasticity in a high-strength Al-Mn-Sc based alloy produced by laser powder bed fusion

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Journal of Materials Science & Technology 2022年第8期103卷 121-133页

作者： dina Bayoumy Kwangsik Kwak Torben Boll stefan dietrich daniel Schliephake Jie Huang Junlan Yi Kazuki Takashima Xinhua Wu Yuman Zhu Aijun Huang Monash Centre for Additive Manufacturing 15-17 Normanby RdNotting HillVIC 3168Australia department of Materials Science and Engineering Monash UniversityClaytonVIC 3800Australia department of Materials Science and Engineering Kumamoto University2-39-1 KurokamiChuo-kuKumamoto 860-8555Japan Karlsruhe Nano Micro Facility(KNMF) Karlsruhe Institute of Technology(KIT)Hermann-von-Helmholtz-Platz 176344Eggenstein-LeopoldshafenGermany Institute for Applied Materials(IAM-WK) Karlsruhe Institute of Technology(KIT)Engelbert-Arnold-Straße 476131 KarlsruheGermany Aeronautical Manufacturing Technology Institute Shanghai Aircraft Manufacturing Co.Ltd.Shanghai 201324China

The Al-Mn-Sc-based alloys specific for additive manufacturing(AM)have been recently developed and can reach ultrahigh strength and adequate ***,these alloys commonly exhibit nonuniform plasticity during tensile deformation,which is a critical issue hindering their wider *** this work,the origin of this non-uniform plasticity of the alloys produced by laser powder bed fusion(LPBF)has been systematically investigated for the first *** results show that the loss of uniform plasticity in the alloy originates from microstructural regions containing equiaxed fine-grains(FGs)(~650nm in size)at the bottom of the melt *** micro-tensile tests,the strength of these FG regions can reach a peak of~630 *** this,an apparent yield drop occurs,followed by rapid strain *** FG behavior is associated with intermetallic particles along grain boundaries and a lack of uniform mobile dislocations during *** columnar coarse-grain(CG)regions in the remaining melt pools show uniform plasticity and moderate work ***,the quantitative calculations indicate that the solid solution strengthening in these two regions is ***,secondary Al_(3)Sc precipitates contribute to~260 MPa strength in the FG,compared to 310 MPa in the CG due to their different number *** addition,grain boundary strengthening can reach 230 MPa in the FG region;nearly double the CG region value.

关键词： Aluminium alloy Laser powder bed fusion Crystal plasticity Microstructures Strengthening

Flexible Furnace Concepts for Vacuum Heat Treatment Combined with High-pressure Gas Quenching

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材料热处理学报 2004年第5期25卷 607-611页

作者： Karl killer stefan Wiebach ALd Vacuum Technologies AG Hanau - GermanyALD Vacuum Technologies AG Hanau - Germany

IN the past five years the process combination of vacuum hardening, respectively vacuum carburizing with high-pressure gas quenching was successfully introduced to the market, especially in the manufacture of gears. In the meantime furnace concepts for various applications are available to the industry. In the following report three plant varieties are introduced, which differ in process flexibility and throughput. This report also explains criteria for the selection of a furnace in view of the existing application requirements. Besides this a short introduction is given into the vacuum carburizing process and the high-pressure gas quenching technology.

关键词：真空热处理真空渗碳高压气体流淬火炉子

Impact of Si on the high-temperature oxidation of AlCr(Si)N coatings

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Journal of Materials Science & Technology 2022年第5期100卷 91-100页

作者： Nikolaus Jager Michael Meindlhumer Michal Zitek stefan Spor Hynek Hruby Farwah Nahif Jaakko Julin Martin Rosenthal Jozef Keckes Christian Mitterer Rostislav daniel Christian doppler Laboratory for Advanced Synthesis of Novel Multifunctional Coatings at the department of Materials Science Montanuniversität LeobenAustria voestalpine eifeler Vacotec GmbH DüsseldorfGermany Institute of Ion Beam Physics and Materials Research Helmholtz-Zentrum Dresden-RossendorfDresdenGermany department of Physics University of JyvaskylaFinland European Synchrotron Radiation Facility GrenobleFrance Erich Schmid Institute for Materials Science Austrian Academy of SciencesAustria department of Materials Science Montanuniversität LeobenAustria

The resistance of wear protective coatings against oxidation is crucial for their use at high ***,three nanocomposite AlCr(Si)N coatings with a fixed Al/Cr atomic ratio of 70/30 and a varying Si-content of 0 at.%,2.5 at.% and 5 at.% were analyzed by differential scanning calorimetry,thermogravimetric analysis and X-ray in order to understand the oxidation behavior depending on their ***,a partially oxidized AlCrSiN coating with 5 at.%Si on a sapphire substrate was studied across the coating thickness by depth-resolved cross-sectional X-ray nanodiffraction and scanning trans-mission electron microscopy to investigate the elemental composition,morphology,phases and residual stress evolution of the oxide scale and the non-oxidized coating *** results reveal enhanced oxidation properties of the AlCr(Si)N coatings with increasing Si-content,as demonstrated by a retarded onset of oxidation to higher temperatures from 1100℃ for AlCrN to 1260℃ for the Si-containing coatings and a simultaneous deceleration of the oxidation *** annealing of the AlCrSiN sample with5 at.%Si at an extraordinary high temperature of 1400℃ for 60 min in ambient air,three zones developed throughout the coating strongly differing in their composition and structure:(i)a dense oxide layer comprising an Al-rich and a Cr-rich zone formed at the very top,followed by(ii)a fine-grained transition zone with incomplete oxidation and(iii)a non-oxidized zone with a porous *** varying elemental composition of these zones is furthermore accompanied by micro-structural variations and a complex residual stress development revealed by cross-sectional X-ray *** results provide a deeper understanding of the oxidation behavior of AlCr(Si)N coatings depending on their Si-content and the associated elemental,microstructural and residual stress evolution during high-temperature oxidation.

关键词： AlCrSiN Nanocomposite Cathodic arc Oxidation behaviour Cross-sectional X-ray nanodiffraction

database and primer selections affect nematode community composition under different vegetations of Changbai Mountain

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Soil Ecology Letters 2023年第1期5卷 142-150页

作者： Yixin Sun Xiaofang du Yingbin Li Xu Han Shuai Fang stefan Geisen Qi Li CAS Key Laboratory of Forest Ecology Management Institute of Applied EcologyChinese Academy of SciencesShenyang 110016China University of Chinese Academy of Sciences Beijing 100049China Laboratory of Nematology Wageningen UniversityWageningenThe Netherlands

High-throughput sequencing technology is increasingly used in the study of nematode ***,the annotation difference of commonly used primers and reference databases on nematode community is still *** compared two pairs of primers(3Ndf/C_1132rmod,NF1F/18Sr2bR)and three databases(NT_V20200604,SILVA138/18s Eukaryota and PR2_v4.5 databases)on the determination of nematode community from four different vegetation types in Changbai Mountain,including mixed broadleaf-conifer forest,dark coniferous forest,betula ermanii Cham and alpine *** results showed that the selection of different primers and databases influenced the annotation of nematode taxa,but the diversity of nematode community showed consistent pattern among different vegetation *** findings emphasize that it is necessary to select appropriate primer and database according to the target taxonomic *** difference in primers will affect the result of nematode taxa at different classification levels,so sequencing analysis cannot be used for comparison with studies using different *** terms of annotation effect in this study,3Ndf/C_1132rmod primers with NT_v20200604 database could provide more information than other combinations at the genus or species levels.

关键词： Soil nematodes Primer database High-throughput sequencing Community composition