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finite cell method compared to h-version finite element method for elasto-plastic problems

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Applied Mathematics and Mechanics(English Edition) 2014年第10期35卷 1239-1248页

作者： A.ABEDIAN J.PArVIZIAN A.DSTEr E.rANK Department of Mechanical Engineering Daneshpajoohan Higher Education Institute Department of Mechanical Engineering Isfahan University of Technology Numerische Strukturanalyse mit Anwendungen in der Schiffstechnik (M-10) Technische Universitt Hamburg-Harburg lehrstuhl fr Computation in Engineering Fakultt fr Bauingenieur-und Vermessungswesen Technische Universitt Mnchen

The finite cell method （fCM） combines the high-order finite element method （fEM） with the fictitious domain approach for the purpose of simple meshing. In the present study, the fCM is used to the Prandtl-reuss flow theory of plasticity, and the results are compared with the h-version finite element method （h-fEM）. The numerical results show that the fCM is more efficient compared to the h-fEM for elasto-plastic problems, although the mesh does not conform to the boundary. It is also demonstrated that the fCM performs well for elasto-plastic loading and unloading.

关键词： finite cell method (fCM) h-version finite element method (h-fEM),Prandtl-reuss quadtree octree

The Swelling Equilibria of N-isopropylacrylamide Based Hydrogel in Aqueous Solution of Ethanol

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Chinese Journal of Chemical Engineering 2003年第3期11卷 264-268页

作者：许小平 HüTHEr Andreas MAUrEr Gerd Department of Chemical Engineering Fuzhou UniversityFuzhou 350002China lehrstuhl für technische thermodynamik Universitt KaiserslauternPostfach 304967663 KaiserslauternGermany

N-isopropylacrylamide (NIPAAm) was used to synthesize NIPAAm homopolymer (nonionized) and NIPAAm-sodium methacrylate copolymer (ionized). The swelling equilibria for both gels were obtained in aqueous solution of ethanol with concentration ranging from 0 to 100%(by mass) at 25℃. The swollen gel in water shrank first with the addition of a small amount of ethanol and then reswelled with further addition of ethanol showing not only a discontinuous volume phase transition but also a typical reentrant phenomenon. A thermodynamic model based on the UNIQUAC with the 'free-volume' contribution was applied to correlate and predict the swelling behavior of the poly(NIPAAM)-gels in ethanol-water mixture.

关键词： hydrogel swelling poly(N-isopropylacrylamide) model

MEASUrEMENT Of ADHESION fOrCES IN AIr WITH THE VIBrATION METHOD

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China Particuology 2005年第1期3卷 3-9页

作者： Siegfried ripperger Konrad Hein lehrstuhl für Mechanische Verfahrenstechnik Technische Universit(a|¨)t Kaiserslautern67653 Kaiserslautern Germany lehrstuhl für Mechanische Verfahrenstechnik Technische Universit(a|¨)t Dresden 01062 Dresden Germany

The vibration method represents a practical method for the measurement of adhesion forces and adhesion force distributions. This method causes sinusoidally alternating stresses and yields detachment and contact forces between particles and substrate of the same order of magnitude. Alternating contact forces of the vibration method can cause an adhesion force intensification through flattening of asperities. The measuring principle of the vibration method and the analysis of experimental results are described in the article. Normal adhesion forces (pull-off forces) are measured using the vibration method and the colloidal probe technique. The results of both methods show good agreement for small particle sizes. The influence of the detachment force direction is shown by comparing tangential and normal adhesion forces measured using particle reentrainment in a turbulent air flow and the vibration method, respectively. The surface roughness of the substrate and the relative humidity are shown to significantly influence the measured adhesion forces. for the calculation of the adhesion forces, an approach by rabinovich was combined with approximations of plastic micro asperity flattening. The rabinovich approach accounts for roughness effects on the van der Waals force by incorporating the rms roughness of the interacting surfaces, rms-values of the particles and substrates were measured with atomic force microscopy at different scanning areas.

关键词： adhesion force vibration method roughness

In situ characterization of particle formation in spray flame synthesis using wide-angle light scattering

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Particuology 2024年第3期86卷 304-312页

作者： Simon Aβmann franz J.T.Huber Stefan Will lehrstuhl für technische thermodynamik(LTT) Friedrich-Alexander-Universitat Erlangen-Nürnberg(FAU)Erlangen91058Germany Erlangen Graduate Schoolin Advanced Optical Technologies(SAOT) Friedrich-Alexander-Universitat Erlangen-Nurnberg(FAU)Erlangen91052Germany Competence Unit Engineering of Advanced Materials(EAM) Friedrich-Alexander-Universitat Erlangen-Nürnberg(FAU)Erlangen91052Germany

Wide-angle light scattering(WALS)was used for in situ measurements of droplet and nanoparticle size distributions during the synthesis of titania and iron oxide particles from liquid precursor solutions in the standardized SpraySyn burner for spray flame *** was synthesized from titanium tetraisopropoxide(TTIP)and iron oxide from iron(II)nitrate nonahydrate(INN)using ethanol(EtOH)as *** images were taken at heights up to 120 mm above the burner surface and classified into droplet and particle *** size distributions were derived from a sequential analysis of scattering data containing the oscillating Mie pattern,the lognormal size distribution parameters for spherical and fractal particle fractions from a multivariate approach on averaged particle scattering *** results show that the precursor addition leads to altered evaporation behavior and even droplet disruption probably induced by puffing or micro-explosions compared to pure *** the case of TTIP(a hygroscopic alkoxide),the synthesis of a large fraction of spheres was observed,while the nitrate INN leads to the formation of mostly fractal aggregates.

关键词： Spray flame synthesis Metal oxide particles Elastic light scattering Droplet size distribution Nanoparticle morphology Particle size distribution

THE EXAMINATION Of TUrBULENCE MODELING WITH LES DATABASE

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Applied Mathematics and Mechanics(English Edition) 1994年第11期15卷 1047-1053页

作者：苏铭德 1. Qinghua University Beijing 2. lehrstuhl für fluidsmechanik technische Universit?t München Germany

In this paper the database obtained from LES is used to examine the algebraicturbulence model in Demuren and rodi’s work. The results show that the prediction ofnormal reynolas stresses and turbulence energy by means of turbulence modeling isbetter than that of shear reynolde stresses. The comparison shows the LES methodcan be used to examine turbulence modelling.

关键词： Turbulence LES (large eddy simulation) turbulence model

Kinematic Analysis of Leaf Growth in Grasses:A Comment on Spatial and Temporal Quantitative Analysis of Cell Division and Elongation rate in Growing Wheat Leaves under Saline Conditions

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Journal of Integrative Plant Biology 2009年第5期51卷 433-436页

作者： Hans Schnyder Monika Kavanova C.Jerry Nelson lehrstuhl für Grünlandlehre Technische Universitt München85350 Freising-WeihenstephanGermany Department of Cell & Developmental Biology John Innes Centre Division of Plant Sciences University of Missouri

Hu and Schmidhalter （2008） conducted a study with wheat seedlings growing in saline and non-stressed （control） conditions with the aim of identifying and quantifying the cellular basis for the reduction in leaf growth. We applaud their goals as salinity is an important issue for plant ecology and food production; however, we have concerns about the methodology used and the subsequent conclusJons that are drawn.

关键词： Kinematic Analysis of Leaf Growth in Grasses cell length

Emission from quantum-dot high-β microcavities: transition from spontaneous emission to lasing and the effects of superradiant emitter coupling

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Light(Science & Applications) 2017年第1期6卷 638-645页

作者： Sören Kreinberg Weng W Chow Janik Wolters Christian Schneider Christopher Gies frank Jahnke Sven Höfling Martin Kamp Stephan reitzenstein 无 Institut für festkörperphysik Technische Universität BerlinBerlin 10623Germany Sandia National Laboratories AlbuquerqueNM 87185-1086USA lehrstuhl für technische Physik Universität WürzburgWürzburg 97074Germany School of Physics and Astronomy University of St AndrewsSt Andrews KY169SSUK Institute for Theoretical Physics University of BremenBremen 28334Germany

Measured and calculated results are presented for the emission properties of a new class of emitters operating in the cavity quantum electrodynamics *** structures are based on high-finesse GaAs/AlAs micropillar cavities,each with an active medium consisting of a layer of InGaAs quantum dots(QDs)and the distinguishing feature of having a substantial fraction of spontaneous emission channeled into one cavity mode(highβ-factor).This paper demonstrates that the usual criterion for lasing with a conventional(lowβ-factor)cavity,that is,a sharp non-linearity in the input–output curve accompanied by noticeable linewidth narrowing,has to be reinforced by the equal-time second-order photon autocorrelation function to confirm *** paper also shows that the equal-time second-order photon autocorrelation function is useful for recognizing superradiance,a manifestation of the correlations possible in high-βmicrocavities operating with *** terms of consolidating the collected data and identifying the physics underlying laser action,both theory and experiment suggest a sole dependence on intracavity photon *** for this assertion comes from all our measured and calculated data on emission coherence and fluctuation,for devices ranging from light-emitting diodes(LEDs)and cavity-enhanced LEDs to lasers,lying on the same two curves:one for linewidth narrowing versus intracavity photon number and the other for g(2)(0)versus intracavity photon number.

关键词： coherence laser physics microlasers nanolasers optoelectronics photon statistics quantum dots quantum optics

UNIQUAC法预报N-异丙基丙烯酰胺凝胶在乙醇水溶液中的溶胀行为

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计算机与应用化学 2003年第6期20卷 783-788页

作者：许小平 HüTHErAndreas MAUrErGerd 福州大学化学化工学院 lehrstuhl für technische thermodynamik Universitat Kaiserslautern Postfach 304967663 KaiserslauternGermany

以N-异丙基丙烯酰胺(NIPAAm)为单体,合成了NIPAAm均聚凝胶。研究了25℃时它们在乙醇水溶液中的溶胀平衡。实验发现;当乙醇浓度约为12％时,少量乙醇的进一步加入将使溶涨的凝胶突然剧烈收缩,表明NIPAAm凝胶在乙醇水溶液中有不连续体积相... 详细信息

以N-异丙基丙烯酰胺(NIPAAm)为单体,合成了NIPAAm均聚凝胶。研究了25℃时它们在乙醇水溶液中的溶胀平衡。实验发现;当乙醇浓度约为12％时,少量乙醇的进一步加入将使溶涨的凝胶突然剧烈收缩,表明NIPAAm凝胶在乙醇水溶液中有不连续体积相变。随着乙醇不断加入,凝胶又重新溶涨。结合“自由体积”概念,利用UNIQUAC模型的关联和预报了NIPAAm凝胶在乙醇-水溶液中的这种溶涨行为。

关键词： UNIQUAC法 N-异丙基丙烯酰胺凝胶制备乙醇水溶液溶胀行为

Single-pulse ultrafast real-time simultaneous planar imaging of femtosecond laser-nanoparticle dynamics in flames

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Light(Science & Applications) 2024年第10期13卷 2312-2320页

作者： Yogeshwar Nath Mishra Peng Wang florian J.Bauer Murthy S.Gudipati Lihong V.Wang Caltech Optical Imaging Laboratory Andrew and Peggy Cheng Department of Medical EngineeringDepartment of Electrical EngineeringCalifornia Institute of Technology1200 East California BoulevardMail Code 138-78PasadenaCA 91125USA Science Division Jet Propulsion LaboratoryCalifornia Institute of Technology4800 Oak Grove DrivePasadenaCA 91109USA lehrstuhl für technische thermodynamik(LTT)and Erlangen Graduate School in Advanced Optical Technologies(SAOT) Universität Erlangen-NürnbergErlangen 91058Germany

The creation of carbonaceous nanoparticles and their dynamics in hydrocarbon flames are still debated in environmental,combustion,and material *** this study,we introduce single-pulse femtosecond laser sheetcompressed ultrafast photography(fsLS-CUP),an ultrafast imaging technique specifically designed to shed light on and capture ultrafast dynamics stemming from interactions between femtosecond lasers and nanoparticles in flames in a ***-CUP enables the first-time real-time billion frames-per-second(Gfps)simultaneous twodimensional(2D)imaging of laser-induced fluorescence(LIf)and laser-induced heating(LIH)that are originated from polycyclic aromatic hydrocarbons(PAHs)and soot particles,***,fsLS-CUP provides the real-time spatiotemporal map of femtosecond laser-soot interaction as elastic light scattering(ELS)at an astonishing 250 *** contrast to existing single-shot ultrafast imaging approaches,which are limited to millions of frames per second only and require multiple laser pulses,our method employs only a single pulse and captures the entire dynamics of laserinduced signals at hundreds of *** a single pulse does not change the optical properties of nanoparticles for a following pulse,thus allowing reliable spatiotemporal ***,we found that particle inception and growth are derived from *** essence,as an imaging modality,fsLS-CUP offers ultrafast 2D diagnostics,contributing to the fundamental understanding of nanoparticle’s inception and broader applications across different fields,such as material science and biomedical engineering.

关键词： pulse scattering dynamics