简介:Forthestabilityrequirementofnumericalresultants,themathematicaltheoryofclassicalmixedmethodsarerelativelycomplex.However,generalizedmixedmethodsareautomaticallystable,andtheirbuildingprocessissimpleandstraightforward.Inthispaper,basedontheseminalideaofthegeneralizedmixedmethods,asimple,stable,andhighlyaccurate8-nodenoncompatiblesymplecticelement(NCSE8)wasdevelopedbythecombinationofthemodifiedHellinger-Reissnermixedvariationalprincipleandtheminimumenergyprinciple.Toensuretheaccuracyofin-planestressresults,asimultaneousequationapproachwasalsosuggested.NumericalexperimentationshowsthattheaccuracyofstressresultsofNCSE8arenearlythesameasthatofdisplacementmethods,andtheyareingoodagreementwiththeexactsolutionswhenthemeshisrelativelyfine.NCSE8hasadvantagesoftheclearingconcept,easycalculationbyafiniteelementcomputerprogram,higheraccuracyandwideapplicabilityforvariouslinearelasticitycompressibleandnearlyincompressiblematerialproblems.ItispossiblethatNCSE8becomesevenmoreadvantageousforthefractureproblemsduetoitsbetteraccuracyofstresses.
简介:Thehighpowerholeyfiberisanefficientsupercontinuumlightsourcebyusingpicosecondpulse,whichisalessexpensivelasersourcecomparedwithlowpowerandexpensivefemtosecondlasersources.Inthispaper,ahighpowerhighlynonlinearholeyfiber(HN-HF)withalowconfinementlossisproposedforsupercontinuumlightsources.ThefinitedifferencemethodisusedtocalculatethedifferentpropertiesoftheproposedHN-HF.Highnonlinearcoefficientsareobtainedat1.06μm,1.31μm,and1.55μmwavelengthswithflattenedchromaticdispersionandlowconfinementlossessimultaneously.Moreover,numericalsimulationresultsshowthathighpowerbroadsupercontinuumspectrawithveryshortlengthoftheproposedphotoniccrystalfiberareachieved.
简介:DistributedBraggreflectors(DBRs)areessentialcomponentsforthedevelopmentofoptoelectronicdevices.Inthispaper,wefirstreporttheuseofthenanoporousGaN(NP-GaN)DBRasatemplateforregrowthofInGaN-basedlight-emittingdiodes(LEDs).Thewafer-scaleNP-GaNDBR,whichisfabricatedbyelectrochemicaletchinginaneutralsolution,hasasmoothsurface,highreflectivity(>99.5%),andwidespectralstopbandwidth(>70nm).ThechemicalcompositionoftheregrownLEDthinfilmissimilartothatofthereferenceLED,butthephotoluminescence(PL)lifetime,PLintensity,andelectroluminescenceintensityoftheLEDwiththeDBRareenhancedseveraltimescomparedtothoseofthereferenceLED.TheintensityenhancementisattributedtothelightreflectioneffectoftheNP-GaNDBRandimprovedcrystallinequalityasaresultoftheetchingscheme,whereastheenhancementofPLlifetimeisattributabletothelatter.
简介:Theyolk-shellFe3O4@Cnanocubesweresuccessfullysynthesizedthroughcarbothermicreductionprocessfromcarbon-coateda-Fe2O3precursor.Theresultsshowthattheyolk-shellFe3O4@Cnanocubesareuniformlycoatedwithathincarbonlayer,andaclearcavityabout150nminwidthbetweenFe3O4coreandcarbonshellareformedduetothevolumeshrinkageduringthereductiontreatment.Theobtainedyolk-shellFe3O4@Cnanocubesexhibitexcellentcyclingstability(thedischargecapacityis709.7mAh/gafter100cyclesatthecurrentdensityof0.1C)andrateperformance(1023.4mAh/gat0.1C,932.5mAh/gat0.2C,756.1mAh/gat0.5C,405.6mAh/gat1C,and332.3mAh/gat2C,andmoreimportantly,whenthecurrentdensityfinallybacksto0.1C,acapacityof776.8mAh/gcanberestored).Theoutstandinglithiumstoragepropertiesmaybeattributedtotheuniqueyolk-shellstructures.
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