简介:Westudyaninventorysysteminwhichproductsareorderedfromoutsidetomeetdemands,andthecumulativedemandisgovernedbyaBrownianmotion.Excessivedemandisbacklogged.Wesupposethattheshortageandholdingcostsassociatedwiththeinventoryaregivenbyageneralconvexfunction.Theproductorderingfromoutsideincursalinearorderingcostandasetupfee.Thereisaconstantleadtimewhenplacinganorder.Theoptimalpolicyisestablishedsoastominimizethediscountedcostincludingtheinventorycostandorderingcost.
简介:Afewclassesoforganiccompoundsarepromisingelectrode-activematerialsduetotheirhighpowerandenergydensities,lowcost,environmentalfriendliness,andfunctionality.Inthepresentwork,thepossibilityofusingKlasonligninextractedfrombuckwheathusksasacathode-activematerialforaprimarylithiumbatteryhasbeeninvestigatedforthefirsttime.Thereactionmechanisminthelithium/ligninelectrochemicalcellwassuggestedbasedonthedeepgalvanostaticdischarge(upto0.005V)dataandcyclicvoltammetryresults.ThedependenceoftheelectrochemicalbehavioroftheKlasonligninonthemillingdegreewasevaluated.Themaximumspecificcapacityoftheligninisequalto600mAhg-1atadischargecurrentdensityof75μAcm-2.BeneficialeffectofthethermaltreatmentoftheKlasonlignincathodeat250°Conthecellperformancewasestablished.Itwasfoundthatthedischargecapacityofthecellincreasedby30%intherangefrom3.3to0.9Vforthetreatedcathodematerial.TheseresultsdemonstratetheprospectsofusingKlasonlignin-basedelectrochemicalcellsaslow-rateprimarypowersources.
简介:Here,wereportthesynthesisofhardcarbonmaterials(RH)madefromnaturalricehuskthroughasinglepyrolysisprocessandtheirapplicationasananodeinsodium-ionbatteries.ThestudiesshowthattheelectrochemicalpropertiesofRHsareaffectedbythetreatmenttemperatures,whichdeterminethematerialsmorphology,inparticular,theirdegreeofgraphitizationandextentofcontinuouschannels(nanovoids).Thelatterareaccessibletosodiumionsandsignificantlycontributetochargestoragecapacityoftheproducedanodes.TheRHsobtainedat1600°Cdeliverthehighestreversiblecapacityof276mAhg-1mainlyduetoinsertionofsodiumionsintothenanovoids.Thisworkdeepensthebasicunderstandingoftheinfluenceofthecarbonizationtemperatureonthesodiumstoragemechanism.
简介:Thispaperproposesanonmonotonicbacktrackingtrustregionalgorithmviabilevellinearprogrammingforsolvingthegeneralmulticommodityminimalcostflowproblems.Usingthedualitytheoryofthelinearprogrammingandconvextheory,thegeneralizeddirectionalderivativeofthegeneralmulticommodityminimalcostflowproblemsisderived.Theglobalconvergenceandsuperlinearconvergencerateoftheproposedalgorithmareestablishedundersomemildconditions.
简介:WedescribeandexperimentallydemonstrateameasuringtechniqueforMach–Zehnderinterferometer(MZI)basedintegratedphotonicbiochemicalsensors.OurtechniqueisbasedonthedirectmeasurementofphasechangesbetweenthearmsoftheMZI,achievedbysignalmodulationononeofthearmsoftheinterferometertogetherwithpseudoheterodynedetection,anditallowsustoavoidtheuseofcostlyequipmentsuchastunablelightsourcesorspectrumanalyzers.Theobtainedoutputsignalisintrinsicallyindependentofwavelength,powervariations,andglobalthermalvariations,makingitextremelyrobustandadequateforuseinrealconditions.Usingasilicon-on-insulatorMZI,wedemonstratethereal-timemonitoringofrefractiveindexvariationsandachieveadetectionlimitof4.1×10-6refractiveindexunits(RIU).
简介:Industrialgrademulti-walledcarbonnanotubes(IG-MWCNTs)arealow-costsubstituteforcommerciallypurifiedmulti-walledcarbonnanotubes(P-MWCNTs).Inthiswork,IG-MWCNTswerefunctionalizedwithtetraethylenepentamine(TEPA)forCO2capture.TheTEPAimpregnatedIG-MWCNTswerecharacterizedwithvariousexperimentalmethodsincludingN2adsorption/desorptionisotherms,elementalanalysis,X-raydiffraction,Fouriertransforminfraredspectroscopyandthermogravimetricanalysis.BoththeadsorptionisothermsofIGMWCNTs-nandtheisostericheatsofdifferentadsorptioncapacitieswereobtainedfromexperiments.TEPAimpregnatedIG-MWCNTswerealsoshowntohavehighCO2adsorptioncapacitycomparabletothatofTEPAimpregnatedP-MWCNTs.TheadsorptioncapacityofIG-MWCNTsbasedadsorbentswasintherangeof2.145to3.088mmol/g,dependingonadsorptiontemperatures.Havingtheadvantagesoflow-costandhighadsorptioncapacity,TEPAimpregnatedIG-MWCNTsseemtobeapromisingadsorbentforCO2capturefromfluegas.
简介:Weproposeapositionsensorlesscontrolschemeforafour-switch,three-phasebrushlessDCmotordrive,basedonthezerocrossingpointdetectionofphaseback-EMFvoltagesusingnewlydefinederrorfunctions(EFs).Thecommutationin-stantsare30°afterdetectedzerocrossingpointsoftheEFs.DevelopedEFshavegreatermagnituderatherthanphaseorlinevoltagessothatthesensorlesscontrolcanworkatalowerspeedrange.Moreover,EFshavesmoothtransitionsaroundzerovoltagelevelthatreducesthecommutationerrors.EFsarederivedfromthefilteredterminalvoltagesvaoandvbooftwolow-passfilters,whichareusedtoeliminatehighfrequencynoisesforcalculationoftheaverageterminalvoltages.Thefeasibilityoftheproposedsensorlesscontrolisdemonstratedbysimulationandexperimentalresults.
简介:Facileproductionofhighqualityactivatedcarbonsfrombiomassmaterialshasgreatlytriggeredmuchattentionpresently.Inthispaper,aseriesofinterconnectedporouscarbonmaterialsfromlotusrootshellsbiomassarepreparedviasimplepyrolysisandfollowedbyaKOHactivationprocess.Thepreparedcarbonsexhibithighspecificsurfaceareasofupto2961m~2/gandlargeporevolume~1.47cm3/g.Inaddition,theresultantporouscarbonsservedaselectrodematerialsinsupercapacitorexhibithighspecificcapacitanceandoutstandingrecyclingstabilityandhighenergydensity.Inparticular,theirspecificcapacitanceretentionwasalmost100%after10500cyclesatacurrentdensityof2A/g.Remarkabely,theimpactofthetailoredspecificsurfaceareasofvariouscarbonsamplesontheircapacitiveperformancesissystematicallyinvestigated.Generally,itwasbelievedthatthehighly-developedporosityfeatures(includingsurfaceareasandporevolumeandporesize-distributions),togetherwiththegoodconductivityofactivatedcarbonspecies,playakeyroleineffectivelyimprovingthestorageenergyperformancesoftheporouscarbonelectrodematerialsinsupercapacitor.
简介:UniqueZnSnanobunsdecoratedwithreducedgrapheneoxide(RGO)wassynthesizedandfoundtoexhibitasynergeticeffectasahighlyefficientandlow-costcounterelectrode(CE)indye-sensitizedsolarcells(DSCs).UsingthisZnS-RGOCE,apowerconversionefficiency(PCE)of7.03%wasachieved.Thisvaluewas53%and41%higherthanthoseofpureZnSandRGOCEs,respectively.TheZnS-RGOnanocompositeisindeedanefficientandcost-effectivePt-likealternativeforiodinereductionreaction.
简介:Wehavedevelopedacost-effectiveandhighlycompact100-Gb/scoarsewavelengthdivisionmultiplexing(CWDM)transmitteropticalsubassembly(TOSA)usinglens-freehybridintegration.Toachievelargealignmenttolerances,distributedfeedbacklaserdiodes(DFB-LDs)arebutt-coupledtoafour-channelsilica-basedplanarlightwavecircuit(PLC)arrayedwaveguidegrating,withthesiliconsub-mountsandPLCadhesivelybonded.Then,aflexibleprintedcircuitisemployedtoconnecttheinternalDFB-LDsandtheexterioroftheTOSApackageforradiofrequencysignaltransmission,eliminatingtheexpensiveceramicfeed-through.ThepackagedCWDMTOSA,whichis15.8mm×7.0mm×6.0mminsize,showsaside-modesuppressionratioof>40dB,a3dBbandwidthof>18GHz,anderror-freetransmissionwithanaverageopticaloutputpowerof>0dBmanddynamicextinctionratioof>4.0dBat25.78125Gb/sovera10kmsingle-modefiberforallfourlanes.