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Contact Angle Determination in Multicomponent Lattice Boltzmann Simulations

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Communications in Computational Physics 2011年第5期9卷 1165-1178页

作者： sebastian Schmieschek Jens Harting Institute for Computational Physics University of StuttgartPfaffenwaldring 2770569 StuttgartGermany Department of Applied Physics Eindhoven University of TechnologyP.O.Box 5135600 MB EindhovenThe Netherlands

Droplets on hydrophobic surfaces are ubiquitous in microfluidic applications and there exists a number of commonly used multicomponent and multiphase lattice Boltzmann schemes to study such *** this paper we focus on a popular implementation of a multicomponent model as introduced by Shan and ***,interactions between different components are implemented as repulsive forces whose strength is determined by model *** this paper we present simulations of a droplet on a hydrophobic *** investigate the dependence of the contact angle on the simulation parameters and quantitatively compare different approaches to determine *** show that the method is capable of modelling the whole range of contact *** find that the a priori determination of the contact angle is depending on the simulation parameters with an uncertainty of 10%to 20%.

关键词： Lattice Boltzmann Shan-Chen model contact angle droplets hydrophobic surface

An Optimised Surface Structure for Passive, Unidirectional Fluid Transport Bioinspired by True Bugs

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Journal of Bionic Engineering 2021年第2期18卷 375-386页

作者： sebastian Lifka Florian Hischen Johannes Heitz Werner Baumgartner Institute of Biomedical Mechatronics Johannes Kepler University LinzAltenberger Straße 694040 LinzAustria Institute of Applied Physics Johannes Kepler University LinzAltenberger Straße 694040 LinzAustria

Some true bug species use droplet-shaped,open-capillary structures for passive,unidirectional fluid transport on their body surface in order to spread a defensive fluid to protect themselves against *** this paper we investigated if the shape of the structures found on bugs(bug-structure)could be optimised with regard to better performance in unidirectional fluid ***,to use this kind of surface structure in technical applications where fluid surface interaction occurs,it is necessary to adapt the structure geometry to the contact angle between fluid and *** on the principal of operation of the droplet-shaped structures,we optimised the structure shape for better performance in targeted fluid flow and increase in flexibility in design of the structure *** adapt the structure geometry and the structure spacing to the contact angle,we implemented an equilibrium simulation of the,the structure surrounding,*** order to verify the functionality of the optimised structure,we designed and manufactured a *** testing this prototype with pure water used as fluid,the functionality of the optimised structure and the simulation could be *** kind of structure may be used on technical surfaces where targeted fluid transport is needed,*** of condensate in order to prevent the surface from mold growth,microfluidics,lab-on-a-chip applications and on microneedles for efficient drug/vaccine coating.

关键词： biomimetics true bugs liquid-surface interaction passive unidirectional fluid transport microfluidics lab-on-a-chip

A NEW APPROACH TO RECOVERY OF DISCONTINUOUS GALERKIN

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Journal of Computational Mathematics 2009年第6期27卷 697-712页

作者： sebastian Franz Lutz Tobiska Helena Zarin Institut für Numerische MathematikTechnische Universitt Dresden Institut für Analysis und NumerikOtto-von-Guericke Universitt Magdeburg Department of Mathematics and Informatics University of Novi SadTrg Dositeja Obradovica 421 000 Novi Sad

A new recovery operator P ：Qn^disc（T）→Qn＋1^disc（M） for discontinuous Galerkin is derived. It is based on the idea of projecting a discontinuous, piecewise polynomial solution on a given mesh T into a higher order polynomial space on a macro mesh M. In order to do so, we define local degrees of freedom using polynomial moments and provide global degrees of freedom on the macro mesh. We prove consistency with respect to the local L2-projection, stability results in several norms and optimal anisotropic error estimates. As an example, we apply this new recovery technique to a stabilized solution of a singularly perturbed convection-diffusion problem using bilinear elements.

关键词： Discontinuous Galerkin Postprocessing Recovery.

Homogalacturonan MethyI-Esterification and Plant Development

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Molecular Plant 2009年第5期2卷 851-860页

作者： sebastian Wolf Gregory Mouille Jerome Pelloux Heidelberg Institute for Plant Science Im Neuenheimer Feld 360 69120 Heidelberg Germany Laboratoire de Biologie Cellulaire Institut Jean-Pierre Bourgin INRA Centre de Versailles-Grignon Route de St Cyr 78026 Versailles France EA3900-BioPI Biologie des Plantes et contrble des Insectes ravageurs Universite de Picardie 33 Rue St Leu 80039 Amiens France

The ability of a plant cell to expand is largely defined by the physical constraints imposed by its cell wall. Accordingly, cell wall properties have to be regulated during development. The pectic polysaccharide homogalacturonan is a major component of the plant primary walls. Biosynthesis and in muro modification of homogalacturonan have recently emerged as key determinants of plant development, controlling cell adhesion, organ development, and phyllotactic patterning. This review will focus on recent findings regarding impact of homogalacturonan content and methylesterification status of this polymer on plant life. Demethyl-esterification of homogalacturonan occurs through the action of the ubiquitous enzyme ＇pectin methyl-esterase＇. We here describe various strategies developed by the plant to finely tune the methyl-esterification status of homogalacturonan along key events of the plant lifecycle.

关键词： Carbohydrate metabolism cell walls Arabidopsis Pectin.

A phononic rectifier based on carbon schwarzite host–guest system

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Chinese Physics B 2020年第12期29卷 50-55页

作者： Zhongwei Zhang Yulou Ouyang Jie Chen sebastian Volz Center for Phononics and Thermal Energy Science School of Physics Science and EngineeringTongji UniversityShanghai 200092China China-EU Joint Laboratory for Nanophononics Tongji UniversityShanghai 200092China Institute of Industrial Science The University of TokyoTokyo 153-8505Japan Laboratory for Integrated Micro and Mechatronic Systems CNRS-IIS UMI 2820The University of TokyoTokyo 153-8505Japan

Thermal rectification is a promising way to manipulate the heat flow,in which thermal phonons are spectrally and collectively *** phononic devices are mostly relying on monochromatic phonons,in this work we propose a phononic rectifier based on the carbon schwarzite host–guest *** using molecular dynamic simulations,we demonstrate that the phononic rectification only happens at a specific frequency of the hybridized mode for the host–guest system,due to its strong confinement ***,a significant rectification efficiency,~134%,is observed,which is larger than most of the previously observed *** study of length and temperature effects on the phononic rectification shows that the monochromaticity and frequency of the rectified thermal phonons depend on the intrinsic anharmonicity of the host–guest system and that the on-center rattling configuration with weak anharmonicity is *** study provides a new perspective on the rectification of thermal phonons,which would be important for controlling monochromatic thermal phonons in phononic devices.

关键词： thermal rectification phonon thermal transport

A COMPARATIVE STUDY OF THE INVENTORY SYSTEM WITH SERVICE FACILITY AND POSTPONED DEMANDS

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Journal of Systems Science and Systems Engineering 2014年第2期23卷 176-195页

作者： J.sebastian Arockia Jenifer B.Sivakumar School of Mathematics Madurai Kamaraj University

In this article, we present a continuous review （s,S） inventory system with a service facility consisting of finite buffer （capacity N ） and a single server. The customers arrive according to a Poisson process. The individual customer＇s unit demand is satisfied after a random time of service, which is assumed to be exponential. When the inventory level drops to s＇an order for Q（= S-s） items is placed. The lead time of reorder is assumed to be exponential distribution. An arriving customer, who finds the buffer is full, enters into the pool of infinite size or leaves the system according to a Bernolli trial. At the time of service completion, if the buffer size drops to a preassigned level L （1 〈 L 〈 N） or below and the inventory level is above s, we select the customers from the pool according to two different policy ： in first policy, with probability p （0 〈 p 〈 1） we select the customer from the head of the pool and we place the customer at the end of the buffer; in the second policy, with p （0 〈 p 〈 1） the customer from the pool is transferred to the buffer for immediate service and after completion of his service we provide service to the customer who is in the buffer with probability one. If at a service completion epoch the buffer turns out to be empty, there is at least one customer in the pool and the inventory level is positive, then the one ahead of all waiting in the pool gets transferred to the buffer, and his service starts immediately. The joint probability distribution of the number of customers in the pool, number of customers in the buffer and the inventory level is obtained in the steady-state case. Various stationary system performance measures are computed and total expected cost rate is calculated. A comparative result of two models is illustrate numerically.

关键词： Continuous review inventory system postponed demands service facility finite waiting hall pool with infinite size

Multi-material additive manufacturing-functionally graded materials by means of laser remelting during laser powder bed fusion

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Frontiers of Mechanical Engineering 2023年第4期18卷 183-193页

作者： Alexander SCHMIDT Felix JENSCH sebastian HÄRTEL Chair of Hybrid Manufacturing Brandenburg University of TechnologyCottbus 03046Germany

Many processes may be used for manufacturing functionally graded *** them,additive manufacturing seems to be predestined due to near-net shape manufacturing of complex geometries combined with the possibility of applying different materials in one *** adjusting the powder composition of the starting material layer by layer,a macroscopic and step-like gradient can be *** further improve the step-like gradient,an enhancement of the in-situ mixing degree,which is limited according to the state of the art,is *** this paper,a novel technique for an enhancement of the in-situ material mixing degree in the melt pool by applying laser remelting(LR)is *** effect of layer-wise LR on the formation of the interface was investigated using pure copper and low-alloy steel in a laser powder bed fusion *** cross-sectional selective electron microscopic analyses were carried *** applying LR,the mixing degree was enhanced,and the reaction zone thickness between the materials was ***,an additional copper and iron-based phase was formed in the interface,resulting in a smoother gradient of the chemical composition than the case without *** Marangoni convection flow and thermal diffusion are the driving forces for the observed effect.

关键词： multi-material additive manufacturing(MMAM) functionally graded materials(FGMs) laser powder bed fusion(L-PBF) laser remelting(LR) pure copper

Effect of Different Calcination Temperatures and Post Annealing on the Properties of Acetic Acid Based Sol-Gel (Na_(0.5)K_(0.5))NbO_3(NKN) Thin Films

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Journal of Materials Science & Technology 2013年第2期29卷 142-148页

作者： sebastian Wiegand Stefan Flege Olaf Baake Wolfgang Ensinger Materials Analysis Group Department of Materials and Geosciences Technische Universitt Darmstadt Petersenstrasse 23 64287 Darmstadt Germany

（Na0.5K0.5）NbO3 （NKN） lead free thin films were synthesized by means of an acetic acid based sol-gel process on Pt/Ti/SiO2/Si substrates. Na-acetate, K-acetate and Nb-pentaethoxide were used as metal precursors and acetic acid as the solvent. The effect of different calcination temperatures on the properties of the NKN films was investigated by X-ray diffraction, scanning electron microscopy, leakage current and hysteresis measurements. Low calcination temperatures led to low currents at high electric fields whereas high calcination temperatures led to low currents at low electric fields. Based on these findings calcination at low temperature was combined with a post annealing treatment. Low leakage currents of 4×10^-4 A/cm2 at 150 kV/cm and 2Pr and 2Ec values of 28 μC/cm2 and 150 kV/cm, respectively, could be obtained. All films were single phase NKN with random crystal orientations and no crack or pore formation was visible on the surface.

关键词： Sol-gel process (Na0.5K0.5)NbO3 Thin film Perovskite Lead-free Piezo material

Synthesis and Characterization of(Na_(0.5)K_(0.5))NbO_3(NKN) Thin Films Formed by a Diol-based Sol-gel Process

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Journal of Materials Science & Technology 2012年第6期28卷 500-505页

作者： sebastian Wiegand Stefan Flege Olaf Baake Wolfgang Ensinger Technische Universitt Darmstadt Department of Materials and GeosciencesMaterials Analysis GroupPetersenstrasse 2364287 DarmstadtGermany

Lead-free （***0.5）Nb03 （NKN） thin films were fabricated by spin coating on Pt/Ti/SiO2/Si substrates by a diol-based sol-gel process. Na-acetate, K-acetate, Nb-pentaethoxide and 1,3 propanediol were used to prepare the NKN precursor solution. Thermal analysis showed two characteristic temperatures of 360 and 600℃. Based on these temperatures, a heat treatment program with pyrolysis at 360℃ and calcination at 600℃ after every layer was used. To avoid inhomogeneities and secondary phases, an excess of sodium and potassium was necessary. To evaluate the proper excess amount of sodium and potassium secondary ion mass spectrometry （SIMS） lateral element maps and X-ray diffraction （XRD） patterns were recorded. An excess amount of 20% led to homogeneous distribution of the elements and to single phase perovskite NKN films with random crystal orientation. Scanning electron microscopy （SEMI images showed a pore free surface with 100 nm grains. The leakage current measurements showed a current of lx10-3 A/cm2 at 150 kV/cm.

关键词： Sol-gel process (Nao.sK0.5)NbO3 Thin film Perovskite Lead-free Piezo material