学科分类
/ 7
131 个结果
  • 简介:Debrisflowsinnaturegenerallyfallintothreegroupsdistinctintheirgraincomposition:water-stoneflow,orsub-viscousdebrisflow,dominatedbycoarsegrains;muddyflow,dominatedbyfinegrains;andviscousdebrisflowcomposedofgrainsinlargerange.Liquid-phasevelocityandsedimentarydeliveryresistanceofsub-viscousdebrisflowhavebeendiscussedbasedonthecompositioncharactersofsub-andhigh-viscousdebrisflows.Itisrevealedthatthepresenceoffinegrainsplaysavitalroleinaffectingresistanceandaveragevelocity,particularlywhenthevolumefractionofgrainsintheflowisrelativelyhigh,i.e.Sv>0.45.Grain-sizedistributionofviscousdebrisflowischaracterizedbyabimodalcurve,whichexplainsthepropertieslikehighdensityandlowresistancegradientofdebrisflows.Acalculationformulaisfinallyputforward,whichhastosomeextentovercomelocalitylimitsandachievedagoodagreementwiththefieldobservationsofdebrisflowsinSouthwestChina.

  • 标签: Sub-viscous DEBRIS flow Viscous DEBRIS flow Grain composition Concentration Velocity
  • 简介:AnonlinearBurgers’modelisusedtodescribeverticalinfiltrationofwaterintoanon--swellingsoilwithprescribedconcentrationconditionsattheboundary.Theexactsolutionisconstructedintermsofaseriesinvolvingcomplementaryerrorintegrals.

  • 标签: exact INFILTRATION COMPLEMENTARY PRESCRIBED BURGERS 十华
  • 简介:Insteady,solid-liquidtwo-phaseturbulentflows,thereexisttwotypicalpatternsoftheverticaldistributionofparticleconcentration.ThepatternIshowsamaximumconcentrationatanelevationabovethebed.ThepatternIIshowsanincreaseoftheparticleconcentrationdownwardoverthewholevertical,withthemaximumatthebed.MostofthetheoriesonparticleconcentrationdistributionhavebeendonewiththepatternII,anditislackofasuccessfultheorycovetingbothofthetwopatterns.Thispaperreviewstheparticledistributiontheories,includingthediffusiontheory,themixturetheory,theenergytheory,thesimilaritytheory,thestochastictheoryandthekinetictheory.Thekinetictheoryisalsoappliedtodescribetheverticaldistributionofparticleconcentrationinbothdiluteanddenseflows.

  • 标签: PARTICLE CONCENTRATION distribution DIFFUSION theory KINETIC
  • 简介:Thepaperpresentsexperimentalstudyofdebrisflows.Theequilibriumconcentrationofsolidparticleintheflowisafunctionoftheenergyslope,densityofsolidparticleandkineticfrictionangleofparticles.Thekineticfrictionangleisafunctionofinternalfrictionangle,theconcentrationofsolidparticlesandthemaximumpossibleconcentration.Todeterminethefunctionbetweenthekineticfrictionangleandinternalfrictionangleistheaimofthisresearch.Flumeexperimentsofequilibriumconcentrationaboutparticlesinwaterandslurrywereconducted.Thelargedensityslurrymadethecoarseparticlesbeabletomoveinsmallslope.Thefunctionbetweenthekineticfrictionangleandinternalfrictionanglewasfoundfromtheseexperiments.Thecoarseparticlesandfineparticlesarewellmixed.D50demarcationlinewassuggestedinthispapertodemarcatethecoarseparticleandfineparticleofdebrisflows.TheequilibriumconcentrationofdebrisflowswascalculatedbyusingDs0demarcationforthedebrisflowsinfield.Theequilibriumconcentrationofdebrisflowscalculatedbythefunctionbetweenthekineticfrictionangleandinternalfrictionanglewasclosetotheequilibriumconcentrationdataofdebrisflowsinfield.

  • 标签: DEBRIS flows EQUILIBRIUM concentration SORTING of
  • 简介:Theeffectsofheatlossonthestructureoflaminarflamelets,whicharetheconstitutiveelementsofturbulentflamesunderthemostcommonoperatingconditions,areinvestigatedfortypicalaeronauticalgas-turbineoperatingconditionsattake-off.Themagnitudeofheatlossisquantifiedviathe"enthalpydefect"measuredwithrespecttoanadiabaticflame.Aproceduretogeneratelaminarflameletswithanassignedenthalpydefectattheboundariesisdevisedandappliedtononpremixedpropane/airflames,aspropanereproducestheessentialfeaturesofhigherhydrocarboncombustion.Itisfound,contrarytocommonlyheldbeliefs,thattheenthalpydefecthasasignificanteffectontheconcentrationnotonlyofminorspecies,butalsoofmainreactionproducts.Sucheffectsarefoundingeneraltobemorepronouncedforfuel-richconditions.Animpactisanticipatedontheformationrateofnitricoxides.Theeffectsofscalardissipationratearealsodiscussed.

  • 标签: 火焰结构 热损失 浓度 物种 航空燃气轮机 层流火焰
  • 简介:在2006年5月,高紧张野火在Daxing'an山发生在Songling森林区域,中国。八个离子的集中变化(K[+],Na[+],Ca[2+],Mg[2+],Cl,Br,NO3;SO4[2])被测量在烧;在到2006年10月的从5月的火以后的未燃的溪流。大多数离子流动是更高的在的结果表演在采样时期期间在未燃的溪流比那烧了溪流,;从烧的溪流搬运的大多数离子的最大的集中发生在7月。在火以后,大多数振幅化学药品离子是Ca[2+],谁的平均集中,是5.50mg·L[1]比那高在里面未燃的溪流,;每个化学离子的全部的集中介绍趋势Ca[2+]>SO4[2]>Na[+]>Mg[2+]>NO3。Ca的平均集中[2+],SO4[2],Na[+],Mg[2+],NO3显示出K的一个增加趋势,而是那些[+],Cl,Br有一个减少的趋势。SO4[2]在这些阴离子之中有最大的损失,由NO3列在后面。总的来说,阳离子的增加度比在烧以后的阴离子的大。

  • 标签: 森林防火 河流 水质量 养分 射击效果
  • 简介:Thepresentpaperisfocussedontheeffectsofviscousandturbulentshearstressesonbothverticalvelocityandconcentrationdistributionsinlargesuspensionofsands.Whentheflowcarrieslargeamountofsedimentsinsuspension,thepropertiesoffluidmixturearechangedintermsofmodifiedviscosity,densityandfallvelocity,andhencetheflowcharacteristics.Theoreticalmodelshavebeendevelopedforbothvelocityandconcentrationprofiles,takingintoaccounttheviscousandturbulentshearstresses,whicharethefunctionofvolumetricconcentration.Comparisonoftheoreticalmodelswithexperimentaldatarevealsthat(i)themodifiedvelocityandconcentrationprofilesagreewellwiththeobserveddataforhighsuspension,(ii)thehigherthesedimentsuspension,thesmallerthevonKarmanconstant,and(iii)sedimentdiffusioncoefficientislessthanmomentumdiffusioncoefficientforfinesandsinsuspension.

  • 标签: SEDIMENT suspension Viscosity Turbulent shear stress Hindered settling Velocity and
  • 简介:Logicqubitplaysanimportantroleincurrentquantumcommunication.Inthispaper,weproposeanefficiententanglementconcentrationprotocol(ECP)foranewkindoflogicBellstate,wherethelogicqubitistheconcatenatedGreenber-Horne-Zeilinger(C-GHZ)state.OurECPreliesonthenondemolitionpolarizationparitycheck(PPC)gatesconstructedwithcross-Kerrnonlinearity,andcandistillonepairofmaximallyentangledlogicBellstatefromtwosamepairsofless-entangledlogicBellstates.BenefitfromthenondemolitionPPCgates,theconcentratedmaximallyentangledlogicBellstatecanberemainedforfurtherapplication.Moreover,ourECPcanbercpeatedtofurtherconcentratetheless-entangledlogicBellstate.ByrepeatingtheECP.thetotalsuccessprobabilitycanbeeffectivelyincreased.Basedonabovefeatures,thisECPmaybeusefulinfuturelong-distancequantumcommunication.

  • 标签: CONCATENATED Greenber-Horne-Zeilinger (C-GHZ) state single PHOTON
  • 简介:ObjectivesPlasmauricacid(UA)concentrationwassuspectedtoelevateinelderlywithischemiccardiomyopathy(ICM).MethodsWeanalyzedthedataof235elderlyaged60yearsandolderwithcoronaryheartdisease:silentmyocardialischemiaoranginapectorisconfirmedbyangiography.Amongthesepatients,154hadICMdefinedasleftventricularend-diastolicdiameter(LVDd)male>55mm,female>50mm(mean:63.51±7.70mm)measuredbyechocardiography.DifferenceinUAwasanalyzedbetweenpatientswithandwithoutICM.ResultsTherewassignificantincreaseofUAinICMcomparedwithnon-ICM(432.82±143.05umol/Lvs361.06±137.35umol/L,P<0.05);andUAwaspositivelyrelatedtoLVDd(r=0.25,P<0.05).ConclusionsTherewassignificantincreaseofUAinelderlywithICMduetolongtermsilentmyocardialischemiaandanginapectoris.Moreover,UAwaspositivelyrelatedtoLVDd.

  • 标签: 心肌缺血 老年人 酸浓度 心肌病 尿酸 ICM
  • 简介:ObjectiveTorecordtheendocochlearpotential(EP)andcalculatepotassiumconcentration[K+]inMinipigcochleae.MethodsWeusedmulti-barreledelectrodestomeasuretheEPandthepotential,[K+].EPandpotassiumelectroderecordingweremadein9cochleaefrom5minipigstogetnormalEPvalues.ResultsTheaverageEPvalueinthecochleafromtheminipigswas77.3±14mV.Theaverage[K+]fortheminipigswas147.1±13mM.ConclusionsTheEPandpotential,[K+]inminipigsarelowerthaninthehumanandrodents.ThismaybethereasonwhyporcineABRthresholdsareslightlyhigherthanhumansandrodents.

  • 标签: stria vascularis POTASSIUM SECRETION endocochlear POTENTIAL