简介:Backconversionisanintrinsicphenomenoninnonlinearfrequencydown-conversionprocesses.However,thephysicalreasonforitsoccurrenceisnotwellunderstood.Here,wetheoreticallyrevealthatbackconversionistheresultofaπ-phasejumpassociatedwiththedepletionofoneinteractingwave.Bysuppressingtheidlerphasejumpthroughadeliberatecrystalabsorption,thebackconversioncanbeinhabited,thusenhancingtheconversionefficiencyfromthepumptothesignal.TheresultspresentedinthisLetterwillfurthertheunderstandingofnonlinearparametricprocessesandpavethewaytowardthedesignofhighlyefficientdown-conversionsystems.
简介:1、词汇缺项及弥补方式词汇缺项(lexical gap)是人类语言中普遍存在的一个问题。一般而言,特指的名词在数量上远远超过特指的动词。例如,英语中原本不存在表示诸如“为……理发剃须”、“在……上洒(或浇)水”等具体行为的特指动词。为了达意,人们只得采取迂回的方式,通过“cutthehairand(shave)thebeard for…”,“pourwater over…”等等这一类旧词搭配而成的结构来解决上述所举的特指词汇缺项问题。追求经济、简洁是人类普遍存在的一大心理趋向,而英语中N→V Conversion(名词转化为动词)便是人类这—心理特征在语言上的反映。“转化”这一简
简介:Theobjectiveofthispaperistocomparetheperformancesoftheturbines,whichcouldbeusedforwaveenergyconversioninthenearfuture,undervariousirregularwaveconditions.Theturbinesincludedinthepaperareasfollows:(1)Wellsturbinewithguidevanes;(b)impulseturbinewithself-pitch-controlledguidevanes;(c)impulseturbinewithfixedguidevanes.Inthisstudy,experimentalinvestigationswerecarriedouttoclarifytheperformancesoftheturbinesundersteadyflowconditions,andthenanumericalsimulationwasusedforpredictingtheperformancesunderirregularwaveconditionswithvarioussignificantwaveheights.Asaresult,itwasfoundthattherunningandstartingcharacteristicsoftheimpulseturbinescouldbesuperiortothoseoftheWellsturbine.
简介:TransmissionofananisotropicmetasurfaceisanalyzedinapolarbaserelyingontheJonescalculus,andpolarizationconversionfromthespatialuniformpolarizationtothespatialnonuniformpolarizationisexplored.Simpleandcompactpolarizationconvertersbasedonrectangularholesorcrossholesetchedinsilverfilmaredesigned,andpolarizationconversionsfromthelinearandcircularpolarizationtotheradialandazimuthalpolarizationarerealized.Numericalsimulationsofthreedesignedpolarizationconvertersconsistingofrectangularholesequivalenttopolarizersandquarter-andhalf-waveplates,exhibittheperfectpolarizationconversion.Theexperimentresultsconsistentwiththesimulationsverifytheoreticpredictions.Thisstudyishelpfulfordesigningmetasurfacepolarizationconvertersandexpandingtheapplicationofametasurfaceinpolarizationmanipulations.
简介:Directconversionofmethanetohigherhydrocarbonsisaneffectiveprocesstosolvetheproblemofnaturalgasutilization.Althoughremarkableprogresshasbeenachievedonthedehydro-aromatizationofmethane(DAM),lowconversioncausedbyseverethermodynamiclimitations,cokeformation,andcatalysisdeactivationremainimportantdrawbackstothedirectconversionprocess.MolybdenumcatalystssupportedonHZSM-5typezeolitesupportareamongthemostpromisingcatalysts.Thisreviewfocusesontheaspectsofdirectmethaneconversion,intermsofcatalystscontainingmetalandsupport,reactionconditions,andconversionindifferenttypesofreactors.Thereactionmechanismforthiscatalyticprocessisalsodiscussed.
简介:Thispaperdiscussestheconversionofnitricoxide(NO)withalow-temperatureplasmainducedbyacatalyticpacked-beddielectricbarrierdischarge(DBD)reactor.Aluminaoxide(Al_2O_3),glass(SiO_2)andzirconiumoxide(ZrO_2),threedifferentsphericalpackedmaterialsofthesamesize,wereeachpresentintheDBDreactor.TheNOconversionundervaryinginputvoltageandspecificenergydensity,andtheeffectsofcatalysts(titaniumdioxide(TiO_2)andmanganeseoxide(MnOx)coatedonAl_2O_3)onNOconversionwereinvestigated.TheexperimentalresultsshowedthatNOconversionwasgreatlyenhancedinthepresenceofpackedmaterialsinthereactor,andthecatalyticpackedbedofMnOx/Al_2O_3showedbetterperformancethanthatofTiO_2/Al_2O_3.Thesurfaceandcrystalstructuresofthematerialsandcatalystswerecharacterizedthroughscanningelectronmicroscopyanalysis.ThefinalproductswereclearlyobservedbyaFouriertransforminfraredspectrometerandprovidedabetterunderstandingofNOconversion.
简介:Intheproductionofhotextrusionpipes,thebilletwillbeheatedinaninductionfurnace,beforepiercingorextrusion,toacertaintemperature.Theinductionheatingtemperaturefieldprofileinthebilletwillexertaninfluenceonthedeformationprocesses.ThestudyhasdevelopedandataconversionprogramtoconvertthetemperaturedatafrominductionheatingbyANSYStodeformationsimulationsoftwareDEFORM;therefore,notonlytherelativelyaccuratetemperaturefieldcanbemadeavailable,comparedwiththeusuallyassumeduniformtemperaturefield,butalsotheconnectionbetweeninductionheatinganddeformationcanbeestablished,whichisessentialtoevaluatetheprocessingparameters.Numericalsimulationofthepiercingprocessesofdifferenttemperaturefieldsbyinductionheatingwascarriedout,andtheresultshaveshownthatthedifferentinitialtemperaturefieldsinthebilletcanleadtodifferentdeformationcurves,whichindicatesthattheconversionprogramisnecessarytostudytheproductionprocessofhotextrusionpipes.
简介:Inordertoimprovetheperformanceofawellsturbinetheeffectofguidevaneswithvariousgapsbetweenturbinerotorandguidevanehasbeenclarifiedbymodeltestingandnumericalsimulation.Theresultshavebeencomparedwiththoseofthecasewithoutguidevanes,ItisfoundthattheoverallCharacteriticsareconsiderablyimprovedbytheinletguidevanes.Furthermore,asuitablechoiceofdesignfactorforthegaphasbeensuggested.
简介:CommercialproductionofvinylchloridefromacetylenereliesontheuseofHgCl2asthecatalyst,whichhascausedsevereenvironmentalproblemandthreatstohumanhealthbecauseofitstoxicity.Therefore,itisvitaltoexplorealternativecatalystswithoutmercury.WereportherethatN-dopedcarboncancatalyzedirectlytransformationofacetylenetovinylchloride.Particularly,N-dopedhighsurfaceareamesoporouscarbonexhibitsaratherhighactivitywiththeacetyleneconversionreaching77%andvinylchlorideselectivityabove98%ataspacevelocityof1.0mLmin-1g-1and200℃.Itdeliversastableperformancewithinatestperiodof100handnoobviousdeactivationisobserved,demonstratingpotentialstosubstitutethenotoriouslytoxicmercuricchloridecatalyst.
简介:这研究的目的是表明杆菌SP3的基本特征并且在不同原油上评估它的效果。紧张SP3是在华东从Shengli油田的一座水库被孤立的能动的、克积极的、生产孢子的杆。紧张SP3的Thecells在5.5-8.5的氢指数范围在高温度成长了直到58℃。grewfacultatively拉紧SP3并且能使用不同器官的底层,并且生产一些代谢物如此的as4-hydroxy-4-methyl-2-pentanone,methyl-2-nitrogen苯并且1,2-benzenedicarboxylic酸bisest嗯。实验室研究证明了紧张变换了并且降级不同部件并且变化物理并且原油的化学性质。紧张SP3降级了原油和原油上的细菌的生长导致了芳香的烃,树脂和沥青质的损失。原油的简历变换将在更轻的烃和全面再分配导致丰富浸透烃。有原油的微生物的相互作用是可变的,取决于微生物引起的种类和原油的化学成分。
简介:有效的氨兆兆赫(THz)洞激光试验性地被报导。不同于象洞couplers和独立网孔couplers那样的过去的设计计划,在我们的系统,输入和输出couplers被扔镍制作ZnSe和高抵抗力的硅底层上的电容的金属性的网孔。因此couplers能不仅作为一个F-P振荡器被构造而且能是封上更容易执行排列的调整与的窗户被使用。为了提高THz激光,输出精力和光子变换效率,象泵紧张那样的主导的因素和煤气的压力试验性地被调查。最后,有在1.09kPa操作的90m波长(3.33THz)的氨激光的1.35mJ兆兆赫放射与9R(16)由402mJ茶CO2激光抽了线被产生,并且6.5%的光子变换效率被完成。
简介:AnewmethodologyofvoiceconversionincepstrumeigenspacebasedonstructuredGaussianmixturemodelisproposedfornon-parallelcorporawithoutjointtraining.Foreachspeaker,thecepstrumfeaturesofspeechareextracted,andmappedtotheeigenspacewhichisformedbyeigenvectorsofitsscattermatrix,therebytheStructuredGaussianMixtureModelintheEigenSpace(SGMM-ES)istrained.Thesourceandtargetspeaker’sSGMM-ESarematchedbasedonAcousticUniversalStructure(AUS)principletoachievespectrumtransformfunction.Experimentalresultsshowthespeakeridentificationrateofconversionspeechachieves95.25%,andthevalueofaveragecepstrumdistortionis1.25whichis0.8%and7.3%higherthantheperformanceofSGMMmethodrespectively.ABXandMOSevaluationsindicatetheconversionperformanceisquiteclosetothetraditionalmethodundertheparallelcorporacondition.TheresultsshowtheeigenspacebasedstructuredGaussianmixturemodelforvoiceconversionunderthenon-parallelcorporaiseffective.