学科分类
/ 25
500 个结果
  • 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.

  • 标签: 单级加氢精制 芳香族 柴油 硫含量 脱硫 石油炼制
  • 简介:剪下页面左下角的奶牛,使其翻过山顶,到达山下的挤奶棚。按照Twinkle,TwinkleLittleStar的曲调演唱这首歌。移动奶牛,沿着花朵翻越山顶,使奶牛到达山下的挤奶棚。上山时,音调逐渐升高;下山时,音调逐渐降低。

  • 标签: 小学 英语教学 教学方法 阅读教学
  • 简介:Low这个词……真是,算是目前最流行的最有力的用来鄙视别人的词了吧。和过去不一样的是,你想看不起谁,无论是他的穿衣打扮、言行举止,还是他为人处世方面,都不用再费心地去想什么侮辱性贬损性词汇,只要摇摇头,冷淡地说一句“他太low了”,立刻体内会分泌一种高大上的物质,让自己感觉好到不得了,俨然上帝视角俯视了一下世界,特别恨铁不成钢。

  • 标签: 言行举止 为人处世
  • 简介:Lowgainfeedbackreferstocertainfamiliesofstabilizingstatefeedbackgainsthatareparameterizedinascalarandgotozeroasthescalardecreasestozero.Lowgainfeedbackwasinitiallyproposedtoachievesemi-globalstabilizationoflinearsystemssubjecttoinputsaturation.Itwasthencombinedwithhighgainfeedbackindifferentwaysforsolvingvariouscontrolproblems.Theresultingfeedbacklawsarereferredtoaslow-and-highgainfeedback.Sincetheintroductionoflowgainfeedbackinthecontextofsemi-globalstabilizationoflinearsystemssubjecttoinputsaturation,therehasbeenefforttodevelopalternativemethodsforlowgaindesign,tocharacterizekeyfeaturesoflowgainfeedback,andtoexplorenewapplicationsofthelowgainandlow-and-highgainfeedback.Thispaperreviewsthedevelopmentsinlowgainandlow-and-highgainfeedbackdesigns.

  • 标签: 增益控制 状态反馈 收入 高增益反馈 半线性系统 综述
  • 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.

  • 标签: 电流镜 低功耗 低电压 性能 高精度 输出电阻
  • 简介:Themanagementofpatientswithseveresymptomaticaorticstenosisandahightransvalvulargradientisstraightforward.Itrequiresaorticvalvereplacement.Managementofaorticstenosispatientswithlowflow,lowejectionfractionandlowgradientisfraught.Suchpatientsrarelyfulfillallthetenetsof“severity”andalsohavesevereleftventriculardysfunction.Bothcircumstancesmaketheoutcomeofaorticvalvereplacementuncertain.Thusthemanagementofthisgroupofpatientsrequiresintegrationofalldiagnosticmodalitiesavailable.Thephysicalexamination,degreeofvalvecalcification,theappearanceofthevalveduringsonographicexaminationandthepresenceofinotropicreserveallcontributeimportantlyinjudgingstenosisseverityandthelikelihoodofsuccessfulvalvereplacement.

  • 标签: AORTIC STENOSIS valvular HEART disease HEART
  • 简介:Themagneticimprovisedexplosivedevices(IEDs),alsocommonlyknownasatypeofastickybomb,issimplyconstructeddevicesyetverylethal.Thispaperputsforwardtheideaofanelectroniccompassthatiscapableofsensingthechangeofamagneticfieldgeneratedbyamagnetandtranslatingitintointerpretabledata,whichcouldactasthebaseforthefurtherstudiesandassistindevelopingagreenerautomatedsystemfordetectingthisdevice.Theelectroniccompassisspecificallychosenforreducingpowerconsumptionofsystemsinadditiontothefactthatitisavailableatalowcost.

  • 标签: 数字传感器 低成本 IED 低功耗 双轴 检测
  • 简介:摘要在Low-E玻璃使用过程中,由于工程技术人员对其类别、特性、功能、生产方式、辩别方式等知识了解不够全面或者不了解,在材料采购、施工、监理等工作中很难分辩识别,本文对Low-E玻璃的特点、类别及区别、鉴别方法进行阐述

  • 标签: LOW-E 玻璃概述 分类区别 鉴别方法 特点
  • 简介:译码性能的涡轮将在为剩余频率和阶段的原因的条件在搬运人抵消的低signal-to-noise比率(SNR)下面承受严肃的降级。在这份报纸,一个改进剩余搬运人频率偏移量评价算法基于upriori概率帮助了(APPA)阶段评价被建议。一起联合反复的涡轮解码器和阶段评估者的一个搬运人同步环被构造,在从涡轮解码器获得的外来的信息被用来帮助反复的阶段评价进程的地方。算法在很低的SNR下面成功地执行的模拟结果表演调节(例如,不到-7.4dB)与大频率偏移量和阶段错误和这的表演,算法离最佳地同步的系统很靠近。

  • 标签: 低信噪比 载波同步 载波频率偏移 TURBO译码器 迭代译码器 相位估计
  • 简介:Au/TbMnO3/YBa2Cu3O7-xcapacitorswerefabricatedonSrTiO3substratesbypulselaserdepositiontechnique,ofwhichelectricpropertieswereinvestigatedinthetemperaturerangefrom25to300K.Bothcurrent-voltagecharacteristicsandjunctionresistanceswithbiasvoltagesshowedremarkabletemperaturedependence,inwhichobviousthermallyexcitedrelaxationprocesseswerefoundbetween150and200K.Atthetemperatureslowerthantheactivationprocess,theleakagecurrentsofthecapacitorswerestudied.Interestingly,athighelectricfield,themechanismoftheleakagewasPoole-Frenkelemission.However,atlowelectricfield,theconductionwasnotOhmic,andideallnJ∝E1/4characteristicswereobserved.Analysisshowedthatthepossibleoriginwasrelatedtotheinherentinhomogeneousnatureofactivationlesspercolatingtransport.

  • 标签: 低电场 电荷载体 运输 脉冲激光沉积技术 电影 低温
  • 简介:InviewofthelimitationsofaRn-GnmodelinthelowfrequencyrangeandthedefectsofanEn-Inmodelincommonusenow,thispaperbuildsacompleteEn-Inmodelaccordingtothetheoryofrandomharmonic.Theparametersforthelow-noisedesignsuchastheequivalentinputnoisyvoltageEns,theoptimumsourceimpedanceZsoptandtheminimumnoisefigureFmincanbecalculatedaccuratelybyusingthisEn-Inmodelbecauseitconsidersthecoherencebetweenthenoisesourcesfully.Moreover,thispaperpointsoutthatitwillcausethemaximum30%miscalculationwhenneglectingtheeffectsofthecorrelationcoefficient7.Usingtheseries-seriescircuitsasanexample,thispaperdiscussesthemethodsfortheEn-InnoiseanalysisofelectroniccircuitspreliminarilyanddemonstratesitscorrectnessthroughthecomparisonbetweenthesimulatedandmeasuredresultsoftheminimumnoisefigureFminofasinglecurrentseriesnegativefeedbackcircuit.

  • 标签: En-In MODEL LOW-FREQUENCY CIRCUITS LOW-NOISE DESIGN
  • 简介:

  • 标签:
  • 简介:ThelowresistancePTCceramicthermistormaterialwithexcellenteleectricalpropertiesaresuccessfullyfabricatedbyrawmaterialsatindustrialrangemadeinourcountryonthestudyofitscompositionexpressionandfabricationprocessbyusingtheadditionofNb,La,Y,Ta,microstructureregulatorBNandASTLphase.Thecompositionanditsfabricationmethodarestudied.TherelationofelectricalpropertiesofthePTCceramicmaterialtoitscompositionexpressionanditsrelatedelectricalpropertiesarediscussed.

  • 标签: 半导体陶瓷 低电阻 PTC 正温度系数 热敏电阻
  • 简介:Thedeterminationofthesoundpowerofasourceissimpleinareverberationchamber,butusuallylowervalvesareobtainedatlowfrequenciesthanthefree-spacevalue.Itisshownthatthesoundpowerdeterminedinareverberationchamberdependsnotonlyonitsfree-spacepower,butalsoonthepositionsofthesourceandthereveiver,aswellasthewaythemeasurementsaremadeandaveraged.Exactandstatisticalformulasarederivedtoaccountforthesefactors.Theresultsexplainthediscrepancyandagreewellwithearlierexperiments.Basedonthetheory,parcticabletechniquesofsoundpowerdetermina-tionarepropesedandcorrectpowerformulaspresented.

  • 标签: chamber averaged EARLIER EXPLAIN corrected FORMULAS
  • 简介:Strainageinginsteelwasfirstobservedduringthe19thcenturywhenthemaximumloadcarryingcapacityofatestpiecewasincreasedafterithadbeenretestedfollowingapreviousseriesoftestinginaplasticrange.Overthelastdecades,agreatdealofresearchhasbeenperformedtogaindeeperinsightsintothephenomenonofstrainageing.Thesynergisticdevelopmentoftheoreticalhypothesisandnewexperimentalevidenceshaspromotedtheunderstandingofthemechanismsunderlyingstrainageing.Thecontentofthispaperisorganizedintofourcomponents.First,wehavecomparedthemaintheoriesdevelopedinrecentyears.Second,wehavesummarizedthemetallurgicaleffectsonthestrainageingbehaviorobservedinexperiments.Moreover,wehavemadeanattempttocorrelatetheexperimentalresultsandtheabove-mentionedtheories.Third,wehaveproposedafeasiblesolutiontocontrolstrainageinginlowcarbonsteels.Finally,wehaveelaboratedthepotentialityoftheatomprobetechniqueinfacilitatingdirectcharacterizationofthedistributionofsoluteatoms.

  • 标签: 应变时效 低碳钢 实验证据 溶质原子 承载试验 最大负荷