简介:为了辅助静脉穿刺及相关的医疗操作,设计了一款基于投影式头戴显示器(HMPD)的静脉显像系统,其光学系统由近红外成像系统和穿透型HMPD构成。利用光学设计软件ZEMAX优化设计近红外成像系统,使其具有F/2.6的大数值孔径,有利于弱反射红外光的收集成像。穿透型HMPD采用与近红外成像系统相同的光学结构,有利于简化系统的加工装调。设计结果表明,近红外成像系统成像质量优异,分辨率达到QXGA(2048×1536)。穿透型HMPD具有18mm的大出瞳直径及25mm的大出瞳距离,场曲小于0.03D,畸变小于0.32%,达到QXGA分辨率显示模式。与现行的静脉显像系统相比,本显像系统结构简单紧凑、佩戴舒适,且具有超高分辨率,是一款适用于辅助医疗的目视系统。
简介:Onenewsesquiterpenecompound,namely,illihenlactoneA(1),andonenewprenylatedC6–C3compound,illihenryioneH(2),alongwiththreeknownsesquiterpenes(3–5)wereisolatedfromthestemsofIlliciumhenryi.Thestructuresof1and2wereelucidatedbyspectroscopicevidenceincludingNMR,HRESIMSandcirculardichroism(CD).Compound2exhibitedaweakinhibitoryratioforbglucuronidasereleaseinducedbyplatelet-activatingfactor(PAF)inratpolymorphonuclearleukocytes(PMNs)invitro.
简介:Inthispaper,weintroduceaconditionweakerthantheLpdifferentiability,whichwecallCpcondition.Weprovethatifafunctionsatisfiesthisconditionatapoint,thenthereexiststhebestlocalapproximationatthatpoint.WealsogiveanecessaryandsufficientconditionforthatafunctionbeLpdifferentiable.Inaddition,westudytheconvexityofthesetofclusterpointsofthenetofbestappoximationsoff,{Pe(f)}ase→0.
简介:ThefirststarsintheearlyUniversewereformedabout400millionyearsafterthebigbang.VerificationoftheexistenceofthesestarsisimportantforourunderstandingoftheevolutionoftheUniverse[1].IthasbeenpredictedthatforPopulation-IIIstellarproductionyields,theabundancesofodd-Zelementsareremarkablydeficientcomparedtotheiradjacenteven-Zelements[2].Astronomersaresearchingforlong-lived,lowmassstarswiththeuniquenucleosyntheticpatternmatchingthepredictedyields[3].
简介:TheeffectofacidcomponentincludingvariousconventionalacidsandtungsticcompoundsonglucosehydrogenationoveraseriesofbinarycatalystsystemcontainingRu/Ccatalystwasinvestigated.TheresultsshowedthatHCl,H2SO4,H3BO3,H3PO4,andHNO3hadnegligibleeffect,whileallthetungsticcompoundsimposedinhibitingeffectsonthehydrogenationofglucoseoverRu/Ccatalyst,andthesuppressingeffectfollowedtheorderofH2WO4>HPW>WO3>AMT>HSiW.Thisorderisthesameastheorderofethyleneglycol(EG)yieldsintheone-potconversionofglucosetoEG,suggestingtheimportantroleofcompetitionbetweenglucosehydrogenationandretro-aldolcondensationincontrollingtheselectivityofEG.
简介:Inthispaper,weintroducegeneralizedcyclicC-contractionsthroughpnumberofsubsetsofaprobabilisticmetricspaceandestablishtwofixedpointresultsforsuchcontractions.InourfirsttheoremweusetheHadzictypet-norm.InournexttheoremweuseLukasiewiczt-norm.OurresultsgeneralizetheresultsofChoudhuryandBhandari[11].Acontrolfunction[3]hasbeenutilizedinoursecondtheorem.Theresultsareillustratedwithsomeexamples.
简介:Arylhalidesareakindofextremelyvaluablecompoundsusedintransition-metal-catalyzedcouplingreactions,aswellasimportantstructuremotifsinmanynaturalproductsandmanufactureddrugs[1,2].Theclassicalapproachforpreparationofhaloarenesiselectrophilicaromaticsubstitution(EAS)usingvarioushalogenatingreagentsoroxidativehalogenationswithhalogenatingreagentgeneratedinsitufromhalidesandoxidants,suchasperoxide,oxygenandmeta-cholorperoxybenzoicacid(mCPBA)[3,4].However,harshreactionconditionsarerequiredforhalogenationoflessactivearomatics.orthoMetalationfollowedbyhalogenquenchingisanotherapproachforhalogenationofaromatics[5].However,thereareobviousdrawbacksforthesemethods,suchaslowregioselectivity,harshconditionsandevendangerousprocedures.Therefore,thedevelopmentofanalternativeandpracticalwayremainschallengeinorganicsynthesis.
简介:Toeffectivelysolvetheagglomerationproblemsinthesolidstatereactionprocess,pre-addingglucoseisadoptedtothesynthesisofLiFePO4/CenergymaterialsusingFe–Pwasteslag.Theaverageparticle&grainsizeofLiFePO4/Cdecreases,andtheimpuritiesinLiFePO4/Ccompositesreducetoagreatextent.Itmakesgreatsensetothemassindustrialproduction.Theoptimumsynthesisconditionsdeterminedinthisworkarebasedontheorthogonalexperiments.Thesamplessynthesizedinascaleof500gexhibithighpurity,excellentelectrochemicalperformance,highreactionactivity,goodreversibility,andlowpolarizationlevel.Thedischargecapacitiesare145,134,117,and102mAh/gatthecurrentdensitiesof0.1C,0.2C,0.5Cand1C,respectively.ThisworkputsforwardapracticalsuggestionformassproducingenvironmentalbenignandlowcostLiFePO4/Cascathodematerialsoflithiumionbatteries.
简介:Theroleofpulseparametersonnanoparticlepropertyisinvestigatedself-consistentlybasedonacoupleoffluidmodelandaerosoldynamicsmodelinacapacitivelycoupledparallel-plateacetylene(C2H2)discharge.Inthismodel,themasscontinuityequation,momentumbalanceequation,andenergybalanceequationforneutralgasaretakenintoaccount.Thus,thethermophoreticforceariseswhenagastemperaturegradientexists.Thetypicalresultsofthismodelarepositiveandnegativeiondensities,electronimpactcollisionsrates,nanoparticledensity,andchargedistributions.Thesimulationisperformedfordutyratio0.4/0.7/1.0,aswellaspulsemodulationfrequencyfrom40kHzto2.7MHzforpureC2H2dischargesatapressureof500mTorr.Wefindthatthepulseparameters,especiallythedutyratio,haveagreataffectonthedissociativeattachmentcoefficientandthenegativedensity.Moreimportantly,bydecreasingthedutyratio,nanoparticlesstarttodiffusetothewall.Undertheactionofgasflow,nanoparticledensitypeakiscreatedinfrontofthepulseelectrode,wherethegastemperatureissmaller.
简介:本文讨论矩阵方程ATX+xTA=C的一般解及其最佳逼近解的正交投影迭代解法.首先,利用矩阵的结构特点及相关性质,并借助矩阵空间的相关理论,给出求该矩阵方程一般解正交投影迭代算法;其次,根据奇异值分解、F-范数正交变换不变性证明算法的收敛性并推导出算法的收敛速率估计式,当方程相容时,该算法收敛于问题的极小范数解,且对该算法稍加修改,就可得到相应最佳逼近解;最后,用数值实例验证算法的有效性.
简介:本文证明第二种服务可选的M/M/1排队模型的主算子的点谱包含一个区间(-α,0),α〉0.此结果表明该主算子生成的C_0-半群不是紧算子,甚至不是最终紧算子.本文的结果与我们以前的结果合并后得到:(i)该C_0-半群的本质增长界为0.从而,该C_0-半群不是拟紧算子.(ii)该模型的时间依赖解不可能指数收敛于其稳态解.(iii)该C_0-半群的本质谱半径等于1.
简介:Theoreticalmodelsofstellarevolutionpredictnegligiblequantitiesof6Li,9Be,and11Binthehydrogenburningphasesofastar’sevolution[1].TheprimordialBig-Bangnucleosynthesis(BBN)modelmightbemoregenerousinitsproductionoftheseelements[2].Theradiative-capturecrosssectionforprotoncaptureon11Bleadingto12CissmallatastrophysicallyinterestingenergiesbecauseofthelargeCoulombbarrier.