简介:对于我来说,钱是无论如何也花不完的,我早已不再将它看作是个人能力的象征。1美元,够了。史蒂夫·乔布斯坐在美国加州CUPERTINO总部的会议室内,这位苹果电脑公司的首席执行官双手托在脑后,全神贯注地听着公司2000年第二财季的财务报告,脸上不时露出欣慰的笑容。在这一财季中,苹果电脑公司共销售计算机系统1,043,000套,实现利润2.33亿美元,与去年同期1.35亿美元的利润收益相比,有了较大幅度的
简介:ThelowresistancePTCceramicthermistormaterialwithexcellenteleectricalpropertiesaresuccessfullyfabricatedbyrawmaterialsatindustrialrangemadeinourcountryonthestudyofitscompositionexpressionandfabricationprocessbyusingtheadditionofNb,La,Y,Ta,microstructureregulatorBNandASTLphase.Thecompositionanditsfabricationmethodarestudied.TherelationofelectricalpropertiesofthePTCceramicmaterialtoitscompositionexpressionanditsrelatedelectricalpropertiesarediscussed.
简介:Thedeterminationofthesoundpowerofasourceissimpleinareverberationchamber,butusuallylowervalvesareobtainedatlowfrequenciesthanthefree-spacevalue.Itisshownthatthesoundpowerdeterminedinareverberationchamberdependsnotonlyonitsfree-spacepower,butalsoonthepositionsofthesourceandthereveiver,aswellasthewaythemeasurementsaremadeandaveraged.Exactandstatisticalformulasarederivedtoaccountforthesefactors.Theresultsexplainthediscrepancyandagreewellwithearlierexperiments.Basedonthetheory,parcticabletechniquesofsoundpowerdetermina-tionarepropesedandcorrectpowerformulaspresented.
简介:Theharmonicanalysismethodbasedonhighandlowwaterlevelsisdiscussedinthispaper.Inordertomakefulluseoftheinformationofhighandlowwaterobservations(thetimederivativeofwaterlevelattheobservationtimeiszero),theweightcoefficient,w,isintroducedtocontroltheimportanceofthepartrelatedtothisinformationintheerrorformula.Themajordiurnalconstituents,O1andK1,andsemi-diurnalconstituents,N2,M2andS2areselecteddirectlyfromthemonthlydataanalysis,andsomeotherimportantconstituents,P1,v2andK2,areincludedastheinferredconstituents.Theobtainedharmonicconstantsofthemajorconstituentsareveryclosetothoseobtainedfromtheanalysisofhourlydata,andthisshowsthathighandlowwaterdatacanbeusedtoextracttidalconstantswithhighaccuracy.Theanalysisresultalsoshowsthattheinferenceandtheweightingcoefficientareimportantinthehighandlowwaterdataanalysis,anditissuggestedthatw≥1shouldbetakeninmonthlyhighandlowwaterdataanalysis.Thisanalysismethodcanbeuseddirectlytoanalyzealtimetricdatawithw=0.
简介:Thereisatypeofnodalsurfaceimposedbysymmetryonwavefunctions.Thesesurfacesarecrucialtotheorderingoflow-lyingstates.Basedonananalysisofthistypeofsurfaceandbasedonexistingtheoreticalresults,thefeatureofthelow-lyingspectrumoftheHe-tetramerisstudied,andthecandidatesofboundstatesandnarrowresonancesaresuggested.