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Three-dimensional particle shape acquisition and use of shape library

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Three-dimensionalparticleshapeacquisitionanduseofshapelibrary

forDEMandFEM/DEMsimulation

John-PaulLathama,*,AntonioMunjizab,XavierGarciaa,JianshengXianga,RomainGuisesa

aEarthScienceandEngineering,ImperialCollege,SouthKensington,LondonSW72AZ,UnitedKingdombDepartmentofEngineering,QueenMaryLondonUniversity,MileEnd,LondonE14NS,UnitedKingdom

articleinfo

Articlehistory:Received20December2007Accepted30May2008Availableonline26July2008

Keywords:DiscreteelementmodellingSimulationMineralprocessingGravityconcentrationSortingmethodsabstract

Numericalsimulationthatwillcapturethecomplexbehaviourofrockfragmentsystems,e.g.,inminingandcivilengineering,requiresboththecomputationalmechanicscapabilitytomodelparticleinterac-tionsbetweencomplexshapesandanassociatedmeanstorepresentthekindofarbitraryorangulargeometryrelevanttoproblemsinvolvingrockfragments.Thispaperisconcernedlesswiththemodellingandmorewiththerepresentation.Here,wefocusonrepresentationgearedto‘softcontact’modellingusingeithercombinedfinite-discreteelement(FEM/DEM)methods,ornon-sphericalDEMmethodssuchasmulti-sphereapproximationsofirregulargeometry.3Dlaserranging(LADAR)isusedtocaptureaston-ishinglyrealisticrockaggregategeometries.Wereportontheworkflowprocedurestogeneratecompu-tationallymeshedvirtualparticlesformodelling.ThedesignofashapelibraryandasuggestedprocedureforselectingvirtualparticlesforinputtoFEM/DEMorDEMmodelsisdiscussedtogetherwiththeuseofinertiamomentsforshapedescriptors.Useoftheshapelibraryforshapedescriptoranalysisisalsoillus-trated.DEMsimulationsofpackingusingirregularparticlesfromtheshapelibraryarepresented.Ó2008ElsevierLtd.Allrightsreserved.

1.Introduction

Ourdevelopmentanduseofavirtualgeoscienceworkbench

(VGW)forthestudyofparticulatesystemshasfocussedinitially

onlengthscalessimilartorockaggregates,i.e.,hand-sizedparti-

cleswhoseinteractionsaredominatedbygravityforces.Thework

ishowever,genericandhaswiderelevance,e.g.,topowdertech-

nologies.Theimportanceoftheinfluenceofparticleshapeinmin-

ing,e.g.,draw-pointandhopperhang-ups,mineralprocessing,civil

engineeringandthebehaviourofbituminous-andcementitious-

boundgeomaterialshascontributedtothedevelopmentanduse

ofDEMandFEM/DEMsimulationtechniquesthatcanhandleirreg-

ularparticleshapeinteractions(e.g.,ClearyandSawley,2002;Fa-

vieretal.,1999;Wangetal.,2007).

Themodellingofinteractionsbetweennon-rigidirregularparti-

clesusingDEMadoptsessentiallytwodifferenttypesofapproach.

Thefirstarethosethatinordertocomputenormalandtangential

contactforcesrelyonawelldefinedparametricformforthecurva-

turesandoverlapvolumesofthecolliding/contactingparticlessuch

asmultisphere,ellipsoidalandsuperquadricmodels.Anintriguing

andpowerfulrecentdevelopmenthasbeentheworkofGarboczi(2002)onsphericalharmonicsrepresentationofnatural

irregularparticlesurfaces.Themostwidelyemployedmodelling

approachofthisDEMtypeistoclumporoverlapspherestocreate

irregulargenerallybumpyorcurvedcompositeparticles(e.g.,Lim

andMcDowell,2005;Favieretal.,1999,2001;Priceetal.,2007).

Such‘‘super-particle”modelsallowtheretentionofthesimplicity

ofsphere-basedDEMmethodsforcomputingcontactforceinterac-

tions,andwheretangentialcontactforceisimplemented,aCou-

lombfrictioncriterionisusuallyapplied.Anotherapproachisto

treattheparticlesascomplexpolyhedramadeupoftetrahedralele-

ments,seeforexamplethecombinedFEM/DEMmethodofMunjiza

(2004)andirregularbodycollisionsolutionsofMunjizaandAn-

drews(2000),Munjizaetal.(2003),whichemployadistributed

contactforceandpenaltyfunctionmethodforthecomputedover-

lapvolumeinvolvingmanytetrahedralnodesineachcollisioncal-

culation.Therealismofearlyresultswithirregularshapedunits

andcubes(LathamandMunjiza2004),suggestssuchFEM/DEM

methodscanhandletheinteractionsbetweencomplex-shapedpar-

ticleswithreasonableaccuracywhichhasencouragedresearchers

toapplyMunjiza’sapproach(e.g.,PolojarviandTuhkuri,2007)

andcontinuetoseekmorerobust3DFEM/DEMmethods.

Anotherreasonformodellingrealisticshapeistocapturethe

breakagebehaviourofgranularmaterialsmorerealistically,irreg-

ulargeometrieswithsharpedgesbeingmuchmoresusceptibleto

breakagethanroundedobjects.Insimulatinggranularcrushingin

pseudo-staticloadingorinimpactsorflowsinvolvingmultiple

0892-6875/$-seefrontmatterÓ2008ElsevierLtd.Allrightsreserved.

doi:10.1016/j.mineng.2008.05.015*Correspondingauthor.Tel.:+4402075947327.E-mailaddresses:j.p.latham@imperial.ac.uk(J.-P.Latham),a.munjiza@qmul.a-c.uk(A.Munjiza),x.garcia06@imperial.ac.uk(X.Garcia),j.xiang@imperial.ac.uk(J.Xiang),r.guises@imperial.ac.uk(R.

Guises).MineralsEngineering21(2008)797–805

ContentslistsavailableatScienceDirect

MineralsEngineering

journalhomepage:www.elsevier.com/lo

cate/mineng

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七年级下册英语书十八页的3d方写作文

七年级下册英语书十八页的3d方写作文

七年级下册英语书十八页的3d方写作文

全文共10篇示例，供读者参考

篇1

Hi guys! Today, I'm going to write a super cool essay about

3D shapes from our 7th grade English book. Let's get started!

3D shapes are shapes that have three dimensions - length,

width, and height. They are like real-life objects that we can

touch and feel. Some examples of 3D shapes are cubes, spheres,

cones, cylinders, and pyramids.

One of the most common 3D shapes is a cube. A cube has six

faces, all of which are squares. It has 12 edges and 8 vertices. You

can find cubes in everyday objects like dice and boxes.

Another cool 3D shape is a sphere. A sphere is perfectly

round, like a ball. It has no edges or vertices. You can find

spheres in nature, like the sun and planets.

Cones are also interesting 3D shapes. They have a circular

base and a pointy tip called the vertex. Cones can be seen in ice

3d粒子旋转爱心代码

3d粒子旋转爱心代码

3d粒子旋转爱心代码

下面是一个使用Three.js库创建的3D粒子旋转爱心的简单示例。请注意，运行此代码需要在支持WebGL的浏览器中查看。

3D粒子旋转爱心

这段代码使用Three.js库创建一个简单的3D场景，其中包含一个由粒子组成的爱心形状。通过在渲染循环中旋转粒子系统，实现了粒子旋转的效果。你可以将这段代码保存为一个HTML文件并在支持WebGL的浏览器中打开以查看效果。

请注意，为了运行这段代码，你需要在HTML文件中引入Three.js库，你可以通过在标签中添加

src="/threejsorg/build/three.js">来引入。

三维可视化英语

三维可视化英语

三维可视化英语

English:

Three-dimensional visualization, also known as 3D visualization, is

the process of creating graphical displays of three-dimensional data

or objects. This technology is commonly used in various fields such

as architecture, medicine, gaming, and manufacturing, allowing users

to interact and manipulate 3D models in a virtual environment.

Three-dimensional visualization has become an essential tool for

designers and engineers to conceptualize and communicate their

ideas more effectively. It provides a more realistic representation of

the object or data, which helps in making better-informed decisions.

Whether it is creating realistic architectural renderings, simulating

medical procedures, designing video games, or visualizing complex

engineering designs, three-dimensional visualization plays a crucial

viral particle vg 单位

viral particle vg 单位

viral particle vg 单位

"Viral particle" 是一个生物学术语，用于描述病毒的基本单位。病毒是一种非常简单的微生物，它只由一个蛋白质外壳（也称为蛋白质囊壳或盖壳）和内部的核酸（DNA或RNA）组成。这些组成部分共同构成了病毒颗粒。

然而，关于 "vg" 这个单位，我无法找到与 "viral particle" 直接相关的信息。在科学计量单位中，"vg" 通常代表 "微微克"，即 10^-12 克。但这个单位似乎并不直接应用于描述病毒颗粒。

对于病毒颗粒的计数或测量，通常使用的单位是 PFU（Plaque Forming Unit，噬斑形成单位）或 TCID50（50% Tissue Culture Infective Dose，组织培养半数感染量）。这些单位用于描述病毒的感染力或活性，而不是直接用于描述病毒颗粒的数量。

如果你是在特定的科学文献或研究中遇到了 "viral particle" 和 "vg" 这两个词，我建议你仔细阅读相关文献或联系该领域的专家以获取更准确和详细的信息。在科学领域，计量单位和术语的使用是非常精确的，不同的领域和上下文可能会有不同的解释和应用。因此，具体的定义和应用可能需要更深入的专业知识和上下文理解。