简介:Fromthegroupmovementofthebedloadwithinthebottomlayer,detailsofthenonlineardynamiccharacteristicsofbedloadmovementarediscussedinthispaper.Whetherthesedimentisinitiatedintomotioncorrespondstowhethertheconstanttermintheequationisequaltozero.Ifconstanttermiszeroandnodispersiveforceisconsidered,theequationrepresentsthetraditionalShieldsinitiationcurve,andifconstanttermiszerowithoutthedispersiveforcebeingconsidered,thenanewShieldscurvewhichismuchlowerthanthetraditionaloneisgot.Thefixedpointoftheequationcorrespondstotheequilibriumsedimenttransportofbedload.Inthemutationanalysis,wehavefoundthattheinflectionpointisthedemarcationpointofbreaking.Intheory,thebreakingpointcorrespondstothedividingboundaryline,acrosswhichthebedformchangesfromflatbedtosandrippleorsanddune.ComparedwiththeexperimentaldataofChatouHydraulicLabinFrance,theconclusionsareverified.
简介:尽管全面结构或结构的成员没完全被破坏,因为高速度水泥碎片,源于接触爆炸的具体平板或墙的分裂在结构内组成风险到人员和设备。正确地预言任何潜力引起的损坏联系爆炸能导致更好的筑堡设计承受强风装载。学习涉及具体平板和墙的分裂的机制因此意义大。这个话题上的存在研究经常采用简化材料模型和1D波浪分析,它不能在分裂过程复制现实主义的反应。数字模拟因此用LS-DYNA在免费的空中在不同接触强风装载下面被执行。复杂具体、增强的酒吧材料模特儿被收养,考虑紧张和压缩上的紧张率效果。侵蚀技术被用来在张力的应力下面为材料的破裂和失败建模。变丑的完整的过程和平板和平凡具体平板这样是的增强的水泥(RC)的动态损坏写实地观察了。随炸药的数量的增加,损坏坑增加和平板的尺寸经历四个不同损坏模式,这被注意,也就是爆炸的坑,spalling,穿孔,并且打。在增强锁的RC平板表演的平凡具体平板和那些的模拟结果之间的比较能提高正直和平板的砍的抵抗到某个程度,并且同时稀释喷射速度和减少水泥的尺寸碎裂。因此,优化加强安排能改进平板和墙的反分裂能力到某个程度。
简介:为前面的kinematics的一个系统的方法一自由(5-DOF)的五度有腿的平行机制“拓扑学4-UPS/UPU,被开发。如此的机制由四相同6-DOF连接到底的一个活动平台组成加有它作为活动站台的指定DOF一模一样的DOF的一活跃手足的活跃手足。Threetranslational和二旋转DOF能被完成。第一,前面的位置分析的一套多项式方程基于机制的建筑学被提出。然后,方程的系统被降级从对五维借助于分析消除三维。最小平方和高斯牛顿算法的方法被用来构造客观功能并且解决它。分别地。通过在16ms以内的4倍的重复,客观功能集成到提供的误差公差的例子表演,10~(-4)。
简介:Basedonthemechanismoftheeffectofhydrationontheheatstabilityoflysozymeandthetheoryofwatermoleculeclusters,theeffectofstructure-changedwateronheatstabilityoflysozymehasbeenstudied.Theresultsobtainedbydifferentialscanningcalorimetry(DSC)showedthatthethermaldenaturationtemperatureoflysozymehadbeenelevated8.47Kthroughhydrationoflysozymewithprocessedwaterwhosestructurehadbeenchangedsoitwascalled'structuredwater'comparedtoordinarywater.Thereasonisthatstructuredwaterchangedthedipolemomentofwatermoleculesandeasilyformedcyclicwaterhexamerorcage-likewaterhexamer,sothattheinteractingforceofmaintainingthree-dimensionalconformationoflysozymecouldbereinforced.
简介:Gainingathoroughunderstandingofthetheoreticalprinciplesofrockbreakingwithadisccutterisacriticalissueintunnelboringmachine(TBM)technology.Tofullyconsiderthecomplexityandimportanceofthebasicprinciplesofrockbreakingduringtunnelexcavation,inthispaperweuseanewmethod,thesmoothparticlehydrodynamics(SPH),tostudytherock-breakingmechanismandverifyitsaccuracyandfeasibility.UsingtheSPHmethod,weinducetherockfragmentationprocesswithtwocuttersinsynchronousandsequentialorders.Theresultsshowthatwhenthecuttersactonrocksequentially,thesecondindentationinfluencesthecrackevolutionofthefirstindentation.Withincreasedcutterspacing,thesecondcrackgraduallybecomesindependentofthefirstcrack.Undersynchronousactionofthetwocutters,abursiformnucleusisgeneratedbeneaththecuttersandtheareaofthenucleusincreaseswithincreasedcutterspacing.Whetherthecuttersactontherocksequentiallyorsynchronously,wefoundtheoptimumcutterspacingofourchosenrocktypetobe60mm.Ouranalysesresultsshowthattheefficiencyofsequentialrockcuttingissuperiortosynchronouscutting,bothwithrespecttocrackevolutionandcutterforce.
简介:Temporalmodedirectnumericalsimulationwasdonefortheprocessoflaminar-turbulenttransitioninanincompressibleboundarylayeronaflatplate.Theanalysisoftheresultsshowedthatduringthebreakdownprocessoflaminar-turbulenttransition,themodificationofthemeanflowprofilebythedisturbancesledtoaremarkablechangeinitsstabilitycharacteristics,manifestedinthesignificantenlargementofthelinearunstablezoneandthemaximumamplificationrate,andledtothatmanymoredisturbanceswereexcitedandenhancedrapidly,correspondinglytheturbulentenergyalsoincreasedrapidly,andthemeanflowprofilesevolvedswiftlyfromlaminartoturbulent.Itwasalsofoundthatiftheobliquewavesintheinitialdisturbancesdidnotformsymmetricalpairs,thesubsequentspan-wisemeanvelocitieswould,ingeneral,benonzeroduetononlinearinteraction,whichwouldhaveagreateffectonthestabilitycharacteristicsandalsoimpliedthattheturbulenceobtainedbydirectnumericalsimulationmightnotbefullyarandomprocess.
简介:根据输入的开车的率更新参数,率依赖者Prandtl-Ishlinskii(PI)模型广泛地在磁滞现象建模和赔偿被使用。以便改进当模特儿的精确性,独立以低、高的开车的率识别的二个PI模型通过一条联合法律被合并。为驾驶piezo的基于弯曲的机制,低抑制比率使使结构的颤动激动容易。作为结果,测量磁滞现象环极大地被弄歪,识别PI模型的当模特儿的精确性显著地被影响。在这份报纸,作为控制输入利用附加正弦曲线信号的一个新奇时间有效的参数鉴定方法被建议。这个方法有效地避免结构的颤动的刺激。另外,作为附加正弦曲线信号的开车的率盖住一个宽范围,为为率依赖建模要求的所有系数能通过仅仅试验性的数据的一个集合被识别。当模特儿的磁滞现象和追踪实验的轨道在2-DOF上被执行驾驶piezo的基于弯曲的机制。试验性的结果证明联合磁滞现象模型在基于弯曲的机制的全部工作范围上维持当模特儿的精确性。机制磁滞现象被反的PI模型的使用显著地作为前馈控制控制器压制;并且当一个反馈环也被合并时,更好的结果被完成。基于弯曲的机制的追踪的表演极大地被改进。