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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

Electric-field driven stability control of skyrmions in an ultrathin transition-metal film

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npj Computational Materials 2022年第1期8卷 992-1000页

作者： Souvik Paul stefan Heinze Peter Grünberg Institut and Institute for Advanced Simulation Forschungszentrum Jülich and JARA52425JülichGermany Institute of Theoretical Physics and Astrophysics Christian-Albrechts-Universität zu KielLeibnizstrasse 1524098KielGermany

To realize future spintronic applications with magnetic skyrmions—topologically nontrivial swirling spin structures—it is essential to achieve efficient writing and deleting capabilities of these ***-field assisted nucleation and annihilation is a promising route,however,the understanding of the underlying microscopic mechanisms is still ***,we show how the stability of individual magnetic skyrmions in an ultrathin transition-metal film can be controlled via external electric *** demonstrate based on density functional theory that it is important to consider the changes of all interactions with electric field,i.e.,the pair-wise exchange,the Dzyaloshinskii–Moriya interaction,the magnetocrystalline anisotropy energy,and the higher-order exchange *** energy barriers for electric-field assisted skyrmion writing and deleting obtained via atomistic spin simulations vary by up to a factor of three more than the variations of the interactions calculated from *** surprising effect originates from the electric-field dependent size of metastable skyrmions at a fixed magnetic *** large changes in lifetimes allow the possibility of electric-field assisted thermally activated writing and deleting of skyrmions.

关键词： field stability film

Can Distributed Ledgers Help to Overcome the Need of Labeled Data for Agricultural Machine Learning Tasks?

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Plant Phenomics 2023年第3期5卷 391-394页

作者： stefan Paulus Benjamin Leiding Institute of Sugar Beet Research Holtenser Landstr.7737079 GöttingenGermany Institute for Software and Systems Engineering TU ClausthalWallstr.638640 GoslarGermany

Introduction Plant phenotyping describes the result of the interaction of genotype with the environment[1].This is performed with high throughput in greenhouses by automated screening systems using different types of imaging and non-imaging sensors[2].The high-throughput imaging routines result in large amounts of data,which require sophisticated processing *** and reusing phenotype-related data are not common,because its acquisition and processing are resource costly and technically intensive[3].

关键词： routine processing throughput

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

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

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

Photovoltaic yield prediction using an irradiance forecast model based on multiple neural networks

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Journal of Modern Power Systems and Clean Energy 2018年第2期6卷 255-267页

作者： Saad Parvaiz DURRANI stefan BALLUFF Lukas WURZER stefan KRAUTER Paderborn University Bosch Thermotechnik GmbH

In order to develop predictive control algorithms for efficient energy management and monitoring for residential grid connected photovoltaic systems, accurate and reliable photovoltaic(PV) power forecasts are required.A PV yield prediction system is presented based on an irradiance forecast model and a PV model. The PV power forecast is obtained from the irradiance forecast using the PV model. The proposed irradiance forecast model is based on multiple feed-forward neural networks. The global horizontal irradiance forecast has a mean absolute percentage error of 3.4% on a sunny day and 23% on a cloudy day for Stuttgart. PV power forecasts based on the neural network irradiance forecast have performed much better than the PV power persistence forecast model.

关键词： Grid connected photovoltaic(GCPV) Photovoltaic(PV) PV power prediction Irradiance forecast Neural network(NN)

Surgical management of peritonitis secondary to acute superior mesenteric artery occlusion

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World Journal of Gastroenterology 2014年第29期20卷 9936-9941页

作者： stefan Acosta Vascular Centre Malm?Sk?ne University Hospital

Diagnosis of acute arterial mesenteric ischemia in the early stages is now possible using modern computed tomography with intravenous contrast enhancement and imaging in the arterial and/or portal *** patients have acute superior mesenteric artery(SMA)occlusion,and a large proportion of these patients will develop peritonitis prior to mesenteric revascularization,and explorative laparotomy will therefore be necessary to evaluate the extent and severity of intestinal ischemia,and to perform bowel *** establishment of a hybrid operating room in vascular units in hospitals is most important to be able to perform successful intestinal *** review outlines current frontline surgical strategies to improve survival and minimize bowel morbidity in patients with peritonitis secondary to acute SMA *** laparotomy needs to be performed *** treatment is based upon intestinal revascularization followed by bowel *** no vascular imaging has been carried out,SMA angiography is *** case of embolic occlusion of the SMA,open embolectomy is performed followed by *** case of thrombotic occlusion,the occlusive lesion can be recanalized retrograde from an exposed SMA,the guidewire snared from either the femoral or brachial artery,and stented with standard devices from these access *** resections and sometimes gall bladder removal due to transmural infarctions are performed at initial laparotomy,leaving definitive bowel reconstructions to a planned second look laparotomy,according to the principles of damage control *** with peritonitis secondary to acute SMA occlusion should be managed by both the general and vascular surgeon,and a hybrid revascularization approach is of utmost importance to improve outcomes.

关键词： Acute mesenteric ischemia Peritonitis Explorative laparotomy Endovascular treatment Hybrid revascularization Superior mesenteric artery occlusion