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Discrete elem.nt sim.lation of cylindrical particles using super-ellipsoids

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Particuology 2019年第5期17卷 55-66页

作者： Yongzhi Zhao Lei Xu Paul B. Um.anhowar richard m. Lueptow Institute of Process Equipm.nt College of Energy Engineering Zhejiang University Hangzhou 310027 China Departm.nt of m.chanical Engineering Northwestern University Evanston Illinois 60208 USA Departm.nt of Chem.cal and Biological Engineering Northwestern University Evanston. Illinois 60208 USA The Northwestern Institute on Com.lex System. (NICO) Northwestern University Evanston Illinois 60208 USA

A discrete elem.nt m.del based on super-ellipsoids was used to sim.late cylindrical particle flow. The m.del can describe a cylindrical particle accurately provided the shape indices of the super-ellipsoids are set to appropriate values. To achieve m.re rapid calculations, we im.lem.nted an "oriented bounding box algorithm.(OBBA) for the initial contact detection of cylindrical particles. Several types of Sim.lations were perform.d to validate the super-ellipsoid m.del and the contact-detection algorithm. First, the effect of shape index of the super-ellipsoids on m.del accuracy was investigated through three sim.lations: im.act of a cylindrical particle on a flat wall, flow of cylindrical particles in a rotating tum.ler, and segregation of cylindrical particles of different length flowing down a bounded heap. The sim.lation results show that the super-ellipsoids describe cylindrical particles accurately when the shape index that specifies the sharpness of the cylinder edges is sufficiently large. The efficiency of the OBBA is m.asured by sim.lations in which a box is filled with cylindrical particles and a tum.ler that contains cylindrical particles is rotated. The sim.lation results show that the OBBA can accelerate the calculations significantly. The effect of particle shape (such as aspect ratio and shape index) on the calculation speed was obtained. The sim.lation of rod-like particles tended to take m.re calculation tim. than that of disk-like particles, and the sim.lation tim. increased with an increasing particle-shape index.

关键词： Discrete elem.nt m.thod Super-ellipsoid Super-quadric Cylindrical particle Non-spherical particle Granular m.terial

Sperm.ne induced reversible collapse of deoxyribonucleic acid-bridged nanoparticle-based assem.lies

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Nano Research 2018年第1期11卷 383-396页

作者： Kristian L. Goeken richard B. m. Schasfoort Vinod Subram.niam.Ron Gill m.RA Institute for Biom.dical Technology and Technical m.dicine University of Twente Dfienerlolaan 5 7522 NB Enschede the Netherlands Vrije UniversiteitAm.terdam De Boelelaan 1105 1081 HVAmsterdam the Netherlands Saxion University of Applied Sciences M. H. Tromplaan 28 7513 A8 Enschede the Netherlands

DNA-linked 2D and 3D nano-assem.lies find use in a diverse set of applications, ranging from.DNA-origam. in drug delivery and m.dical im.ging, to DNA-linked nanoparticle structures for use in plasm.nics and （bio）sensing. However, once these structures have been fully assem.led, few options are available to m.dulate structure geom.try. Here, we investigated the use of the polycation sperm.ne to induce DNA collapse in sm.ll oligonucleotide-linked （54 bp） gold nanoparticle structures by m.nitoring shifts in the localized surface plasm.n resonance （LSPR） peak and by com.aring the data with finite-difference tim.-dom.in （FDTD） sim.lations. Our data shows that low concentrations of sperm.ne can be applied to induce large changes in DNA conform.tion, leading to a significant reduction in interparticle distance （from.- 25 to - 3 nm. and enhanced plasm.nic coupling. The DNA collapse is near-instantaneous and reversible, and its application at low and high DNA densities is dem.nstrated with surface plasm.n resonance im.ging （SPRi）, showing the potential of sperm.ne to dynam.cally m.dulate distances and geom.try in DNA-based nano-assem.lies.

关键词： nanoparticles sperm.ne deoxyribonucleic acid localized surface plasm.nresonance surface plasm.n resonanceim.ging

Wild dogm. II： The role and im.lications of wild dogm. for wild dog m.nagem.nt in Australia

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Current Zoology 2011年第6期57卷 737-740页

作者： Benjam.n L. ALLEN richard m. ENGEm.N Lee R. ALLEN The University of Queensland School of Animal Studies Warrego Highway Gatton QLD 4343 National Wildlife Research Centre 4101 l_aPorte Avenue Fort Collins CO 80521-2154 USA. Richard.M.Engeman@aphis.usda.gov Biosecurity Queensland Robert Wicks Pest Animal Research Centre Tor Street Toowoomba QLD 4350. Lee.Allen@ deedi.qld.gov.au

The studies of Allen （2011） and Allen et al. （2011） recently exam.ned the m.thodology underpinning claim. that dingoes provide net benefits to biodiversity by suppressing foxes and cats. They found m.st studies to have design flaws and/or observational m.thods that preclude valid interpretations from.the data, describing m.st of the current literature as ＇wild dogm.＇. In this short supplem.nt, we briefly highlight the roles and im.lications of wild dogm. for wild dog m.nagem.nt in Australia. We discuss nom.nclature, and the influence that unreliable science can have on policy and practice changes related to apex predator m.nagem.nt

关键词： Apex predator Canis lupus dingo Practice change Public perceptions Wild dog m.nagem.nt

Teaching and learning in STEm

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Teaching and learning in STEM

Feedback Stabilization of Hopf Bifurcationwith SO(2) Sym.etry

作者： (1939-)Felder richard m. (1956-)Brent Rebecca

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Feedback Stabilization of Hopf Bifurcationwith SO(2) Symmetr...

第七届全国非线性动力学学术会议和第九届全国非线性振动学术会议

作者： richard m. m.rray Division of Engineering and Applied Science California Institute of Technology Pasadena California 91125 U.S.A.

— In this paper we analyze the feedback stabi- lizability of Hopf bifurcations with SO(2) sym.etry. The m.de associated with the eigenvalues that becom. linearly unstable is assum.d to be linearly uns

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二阶时滞微分方程边值问题的上下解方法

数学学报（中文版） 2010年第3期53卷 489-494页

作者：王宏洲 richard m. TIm.NEY 北京理工大学数学系北京100081 School of m.them.tics Trinity College DublinDublinIreland

主要利用上下解方法和Schauder不动点定理,研究一类二阶时滞微分方程边值问题的正解存在性.为了验证结论的正确性,本文在结尾部分给出了两个例子.

关键词：边值问题时滞上下解