简介:ThesimultaneousdiagonalizationbycongruenceofpairsofHermitianquatemionmatricesisdiscussed.Theproblemisreducedtoaparalleloneoncomplexmatricesbyusingthecomplexadjointmatrixrelatedtoeachquatemionmatrix.Itisprovedthatanytwosemi-positivedefiniteHermitianquatemionmatricescanbesimultaneouslydiagonalizedbycongruence.
简介:Atwo-stagedelectronicballastwithwidedimmingrange,highpowerfactor(PF)andlowelectromagneticinterference(EMI)ispresented.Itchangestheinputvoltageofthestageofpowerinverterfordimmingcontrol,soitovercomessomelimitationsoftraditionalelectronicballaststhatusefrequencyvariation.Atthesametime,thestageofpowerinverterrunsunderthesoft-switchingatthefixedswitchingfrequencyandreducesEMIgreatly.Itsprincipleandcharacteristicareanalyzedindetail,andexperimentalandsimulatedresultsareobtainedona40Wfluorescentlamp.
简介:Inthispaper,theauthorspointoutanddemonstratethedifferenceoftheconceptsconcerningco-satisfiableandco-validbetweenonefirst-orderlanguageandtwofirst-orderlanguages,andputforwardtheconceptsaboutuniformco-identicaltruthanduniformco-satisfiability.Thussometheoremsinthebook“ACourseinMathematicalLogic”,writtenbyJ.L.BellandM.Machover,arecorrected.
简介:作为在bioethanol生产的设备的一关键片,煮坦克通常被用来保证液化的一致性。在这份报纸,我们建议煮坦克保证在一个大规模过程作为伪塞子流动知道的淀粉泥浆流动的一种类型的一种新奇类型。在流动地的分析,我们使用了计算液体动力学(CFD)。模仿液体固体二阶段的流动,我们基于粒子动力学选择了一个Euler-Euler模型。我们在流动地上调查了几个关键结构的参数的效果。结果与12,800为一辆坦克显示出那?在高度的公里并且1000?在从0潰楳楴湯?瑳畲瑣牵?湡??晲捡?潭灲潨潬祧戠?的直径,优化入口试管角度和入口试管直径范围的公里?慲?楤晦慲瑣潩?攠敮杲?楤灳牥楳敶堠爭祡猠数瑣潲敭牴??卄?堠爭祡瀠潨潴汥'虪箿e数瑣潲捳灯?猠慣湮湩?汥'虪箿珱^驿麙盏?匨??琠慲獮業獳潩?汥'虪箿珱^驿麙盏??卄攠敬敭瑮污洠灡楰杮吗??
简介:AhomogeneoustheoreticalmodelisdevelopedtopredicttheperformanceofR22andR290inadiabaticcapillarytubes.Themodelisbasedonconservationequationsofmass,momentumandenergy.Metastablebothliquidandtwo-phaseflowregionsareconsideredinthemodel.Inmetastabletwo-phaseregion,superheatedliquidisintroducedintothemetastablemixtureviscosityandtwomethodsarepresentedtoevaluateit.Themodelisvalidatedbycomparingthepredictedpressureandtemperatureprofileandmassflowratewithseveralinvestigators′experimentaldataofR22andoneofitsalternativesR290reportedinliterature.Allofthepredictedmassflowratesarewithin±8%ofmeasuredvalues.Comparisonsarealsomadebetweenthepresentmodelandotherinvestigators′modelsorsizingcorrelation.Themodelcanbeusedfordesignorsimulationcalculationofadiabaticcapillarytubes.
简介:CharacteristicsofR22anditsnewalternativerefrigerantR290flowingthroughadiabaticcapillarytubesareinvestigatedbasedonthehomogeneousmodel.Extensiveflowvariablesalongtubelengthsuchaspressure,temperature,viscosity,velocity,Reynoldsnumber,frictionfactorandvaporqualityetcarecomparedbetweenthetwofluidsunderthesameoperatingcondition.Twocasesareconsidered,namely,eitherthesametubelengthorthesamemassflowrateasinletcondition.TheresultsshowthatthemassflowrateinthecapillarytubeofR290is40%lowerthanthatofR22duetothedifferencesofphysicalpropertiesbetweenthetwofluids.Further,aparametricanalysisisperformedanditappearsthateffectsofgeometricandthermodynamicparametersonmassflowrateofR290areweakerthanthatofR22.Whenthecondensingtemperatureisincreasedfrom40℃to50℃,themassflowrateforR22isincreasedby16%,whiletheincreasingrateforR290is13%.