简介:Theneedforcleanerfuelshasresultedinacontinuingworldwidetrendtoreducedieselsulfurandaromatics.Therearemanyapproachestoreducingsulfurandaromaticsindiesel.Mostofthemhaveacommondrawbackofhighcostbecauseofadoptingtwostagesofhydrotreatingandusingnoble-metalcatalyst,especiallyforreducingaromatics.TheattempttoresolvethisissuehasledtotherecentdevelopmentoftheSingleStageHydrotreating(SSHT)processbyResearchInstituteofPetroleumProcessing(RIPP),SINOPEC.TheSSHTprocessisasingle-stagehydrotreatingtechnologyforproducinglowsulfurandlowaromaticsdiesel.Theprocessusesoneortwonon-noble-metalcatalystssystemandoperatesatmoderatepressure.Whenrevampinganexistingunittomeetlowaromaticsdieselspecification,theonlythingtodoistoaddareactororreplacetheexistingreactor,Inpilotplanttests,theSSHTtechnologyhassuccessfullytreatedSRGO(StraightRunGasOil),LCO(LightCycleOil)ortheblendofthem.ItisshownthatbyusingtheSSHTprocessdieselwithsulfurof30ppmandaromaticsof15m%canbeproducedfromMiddle-EastSRGOanddieselwitharomaticscontentof25m%canbeproducedfromcrackedfeed,suchasFCC-LCO.Highdieselyieldandcetanenumbergain(fromcrackedfeedstocks)givetheSSHTtechnologyaperformanceadvantagecomparedtoconventionalhydrocrackingandhydrotreatingprocesses.Thelowerinvestmentandoperatingcostisanotheradvantage.ThefirstcommercialapplicationoftheSSHTtechnologyhasbeeninoperationsinceSeptember2001.
简介:Lowgainfeedbackreferstocertainfamiliesofstabilizingstatefeedbackgainsthatareparameterizedinascalarandgotozeroasthescalardecreasestozero.Lowgainfeedbackwasinitiallyproposedtoachievesemi-globalstabilizationoflinearsystemssubjecttoinputsaturation.Itwasthencombinedwithhighgainfeedbackindifferentwaysforsolvingvariouscontrolproblems.Theresultingfeedbacklawsarereferredtoaslow-and-highgainfeedback.Sincetheintroductionoflowgainfeedbackinthecontextofsemi-globalstabilizationoflinearsystemssubjecttoinputsaturation,therehasbeenefforttodevelopalternativemethodsforlowgaindesign,tocharacterizekeyfeaturesoflowgainfeedback,andtoexplorenewapplicationsofthelowgainandlow-and-highgainfeedback.Thispaperreviewsthedevelopmentsinlowgainandlow-and-highgainfeedbackdesigns.
简介:Anovellowpowerandlowvoltagecurrentmirrorwithaverylowcurrentcopyerrorispresentedandtheprincipleofitsoperationisdiscussed.Inthiscircuit,thegainboostingregulatedcascodeschemeisusedtoimprovetheoutputresistance,whileusinginverterasanamplifier.ThesimulationresultswithHSPICEinTSMC0.18umCMOStechnologyaregiven,whichverifythehighperformanceoftheproposedstructure.Simulationresultsshowaninputresistanceof0.014Ωandanoutputresistanceof3GΩ.Thecurrentcopyerrorisfavorableaslowas0.002%togetherwithaninput(theminimuminputvoltageofvin,min~0.24V)andanoutput(theminimumoutputvoltageofvout,min~0.16V)complianceswhileworkingwiththe1Vpowersupplyandthe50uAinputcurrent.Thecurrentcopyerrorisnearzeroattheinputcurrentof27uA.Itconsumesonly76uWandintroducesaverylowoutputoffsetcurrentof50pA.
简介:Themanagementofpatientswithseveresymptomaticaorticstenosisandahightransvalvulargradientisstraightforward.Itrequiresaorticvalvereplacement.Managementofaorticstenosispatientswithlowflow,lowejectionfractionandlowgradientisfraught.Suchpatientsrarelyfulfillallthetenetsof“severity”andalsohavesevereleftventriculardysfunction.Bothcircumstancesmaketheoutcomeofaorticvalvereplacementuncertain.Thusthemanagementofthisgroupofpatientsrequiresintegrationofalldiagnosticmodalitiesavailable.Thephysicalexamination,degreeofvalvecalcification,theappearanceofthevalveduringsonographicexaminationandthepresenceofinotropicreserveallcontributeimportantlyinjudgingstenosisseverityandthelikelihoodofsuccessfulvalvereplacement.
简介:Themagneticimprovisedexplosivedevices(IEDs),alsocommonlyknownasatypeofastickybomb,issimplyconstructeddevicesyetverylethal.Thispaperputsforwardtheideaofanelectroniccompassthatiscapableofsensingthechangeofamagneticfieldgeneratedbyamagnetandtranslatingitintointerpretabledata,whichcouldactasthebaseforthefurtherstudiesandassistindevelopingagreenerautomatedsystemfordetectingthisdevice.Theelectroniccompassisspecificallychosenforreducingpowerconsumptionofsystemsinadditiontothefactthatitisavailableatalowcost.
简介:Au/TbMnO3/YBa2Cu3O7-xcapacitorswerefabricatedonSrTiO3substratesbypulselaserdepositiontechnique,ofwhichelectricpropertieswereinvestigatedinthetemperaturerangefrom25to300K.Bothcurrent-voltagecharacteristicsandjunctionresistanceswithbiasvoltagesshowedremarkabletemperaturedependence,inwhichobviousthermallyexcitedrelaxationprocesseswerefoundbetween150and200K.Atthetemperatureslowerthantheactivationprocess,theleakagecurrentsofthecapacitorswerestudied.Interestingly,athighelectricfield,themechanismoftheleakagewasPoole-Frenkelemission.However,atlowelectricfield,theconductionwasnotOhmic,andideallnJ∝E1/4characteristicswereobserved.Analysisshowedthatthepossibleoriginwasrelatedtotheinherentinhomogeneousnatureofactivationlesspercolatingtransport.
简介:InviewofthelimitationsofaRn-GnmodelinthelowfrequencyrangeandthedefectsofanEn-Inmodelincommonusenow,thispaperbuildsacompleteEn-Inmodelaccordingtothetheoryofrandomharmonic.Theparametersforthelow-noisedesignsuchastheequivalentinputnoisyvoltageEns,theoptimumsourceimpedanceZsoptandtheminimumnoisefigureFmincanbecalculatedaccuratelybyusingthisEn-Inmodelbecauseitconsidersthecoherencebetweenthenoisesourcesfully.Moreover,thispaperpointsoutthatitwillcausethemaximum30%miscalculationwhenneglectingtheeffectsofthecorrelationcoefficient7.Usingtheseries-seriescircuitsasanexample,thispaperdiscussesthemethodsfortheEn-InnoiseanalysisofelectroniccircuitspreliminarilyanddemonstratesitscorrectnessthroughthecomparisonbetweenthesimulatedandmeasuredresultsoftheminimumnoisefigureFminofasinglecurrentseriesnegativefeedbackcircuit.
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:Strainageinginsteelwasfirstobservedduringthe19thcenturywhenthemaximumloadcarryingcapacityofatestpiecewasincreasedafterithadbeenretestedfollowingapreviousseriesoftestinginaplasticrange.Overthelastdecades,agreatdealofresearchhasbeenperformedtogaindeeperinsightsintothephenomenonofstrainageing.Thesynergisticdevelopmentoftheoreticalhypothesisandnewexperimentalevidenceshaspromotedtheunderstandingofthemechanismsunderlyingstrainageing.Thecontentofthispaperisorganizedintofourcomponents.First,wehavecomparedthemaintheoriesdevelopedinrecentyears.Second,wehavesummarizedthemetallurgicaleffectsonthestrainageingbehaviorobservedinexperiments.Moreover,wehavemadeanattempttocorrelatetheexperimentalresultsandtheabove-mentionedtheories.Third,wehaveproposedafeasiblesolutiontocontrolstrainageinginlowcarbonsteels.Finally,wehaveelaboratedthepotentialityoftheatomprobetechniqueinfacilitatingdirectcharacterizationofthedistributionofsoluteatoms.