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446 个结果
  • 简介:Thechaoticbehaviorofone-dimensional,2-segmentand3-segmentpiecewise-linearmapsisexaminedbyusingtheconceptofsnap-backrepellersintroducedbyMarottoandtheparametersconditionsofexistenceforsnap-backrepellerareobtained.Simulationresultsarepresentedtoshowthesnap-backrepeller,someperiodicpointsandattractingintervalcycleswithchaoticintervals.

  • 标签: 混沌性质 双峰映射 时滞循环 分段线性连续 反射级反驳说 不动点
  • 简介:Generalizedcase-cohortdesignhasbeenprovedtobeacost-effectivewaytoenhancetheefficiencyoflargeepidemiologicalcohort.Inthisarticle,weproposeaninferenceprocedureforestimatingtheunknownparametersinCox’sproportionalhazardsmodelingeneralizedcase-cohortdesignandestablishanoptimalsamplesizeallocationtoachievethemaximumpoweratagivenbudget.Thefinitesampleperformanceoftheproposedmethodisevaluatedthroughsimulationstudies.TheproposedmethodisappliedtoarealdatasetfromtheNationalWilm’sTumorStudyGroup.

  • 标签: 队列分析 风险模型 COX 比例 病例 广义
  • 简介:采用密度泛函理论的B3LYP方法、从头算的MP2方法和自洽反应场极化连续模型(PCM),在6-311++G(2d,2p)基组水平上研究了N,N’-二甲基-S-异苯并呋喃在气相和溶液中发生S→N烷基重排反应的机理、溶剂效应和取代基效应.结果表明:该反应通过四元环机理和双位迁移机理生成产物,在气相和溶剂水中,双位迁移途径的能垒均比四元环途径低,反应主要通过双位迁移途径生成产物.在气相,苯环上发生-Cl,-NO2和-OCH3取代时,双位迁移途径的能垒在MP2/6-311++G(2d,2p)水平上比没有取代时分别低4.18,7.61,4.96kJ/mol,反应的取代基效应不明显.而在溶剂水中,苯环上发生-Cl,-NO2和-OCH3取代时,双位迁移途径的能垒在PCM-MP2/6-311++G(2d,2p)水平上比气相时分别低37.73,39.96和37.17kJ/mol,反应的溶剂化效应非常明显.理论研究结果与实验观察结果一致.

  • 标签: N N’-二甲基-S-异苯并呋喃 S→N烷基重排 溶剂化效应 反应机理 密度泛函理论
  • 简介:Lithiumsulfurbattery(LSB)offersseveraladvantagessuchasveryhighenergydensity,low-cost,andenvironmental-friendliness.However,itsuffersfromseriousdegradationofitsreversiblecapacitybecauseofthedissolutionofreactionintermediates,lithiumpolysulfides,intotheelectrolyte.Tosolvethislimitation,therearemanystudiesusinggraphene-basedmaterialsduetotheirexcellentmechanicalstrengthandhighconductivity.Comparedwithgraphene,grapheneoxide(GO)containsvariousoxygenfunctionalgroups,whichenhancethereactionwithlithiumpolysulfides.Here,weinvestigatedthepositiveeffectofusingGOmixedwithcarbonblackontheperformanceofcathodeinLSB.WehaveobservedasmallerdropofcapacityinGOmixedsulfurcathode.Wefurtherdemonstratethatthemechanisticoriginofreversibilityimprovement,asconfirmedthroughCVandRamanspectra,canbeexplainedbythestabilizationofsulfurinlithiumpolysulfideintermediatesbyoxygenfunctionalgroupsofGOtopreventdissolution.Ourfindingssuggestthattheuseofgrapheneoxide-basedcathodeisapromisingroutetosignificantlyimprovethereversibilityofcurrentLSB.

  • 标签: 多硫化物 氧化石墨 可逆容量 阴极 电池 反应中间体
  • 简介:Inthispaper,wederivetwogeneralparameterizedboundariesoffinitedifferenceschemeforVee’sPDEwhichisusedtopricebothfixedandfloatingstrikeAsianoptions.Usingthesetwoboundaries,wecandealwithallkindsofsituations,especially,someextremecases,likeoverhighvolatility,verysmallvolatility,etc,underwhichtheAsianoptionisusuallymispricedinmanyexistingnumericalmethods.Numericalresultsshowthatourboundariesareprettyefficient.

  • 标签: 期权定价 PDE 边界 胶合板 有限差分方法 数值方法
  • 简介:WestudythestructureofBernstein’sfirstsummableoperatorsandshowthattheycon-vergeuniformlytocontinuonsfunctionsonthespecialrealorthogonalgroupSO(n)inthispaper.Inaddition,wehavealsodiscussedtheapproximationdegreetoaclassoffunctionLipα(0<α≤1)onSO(n).

  • 标签: OPERATORS verge FIRST REAL UNIFORMLY kernel
  • 简介:ForagiventriangulationΔofaregionRofinterest,letS82(Δ):={s∈C2(R):s|1∈P8,l∈Δ}bethespaceofallsplinesofdegree8andsmoothness2,wheretdenotesanytriangleofΔandP8thespaceofpolynomialsoftotaldegree≤8.Furthermore,letS82(Δ):={sS83(Δ):s∈C3atv,v∈Δ}beasupersplinesubspaceofS82(Δ).WeconstruelacollectionoflocallysupportedsplinesinS82(Δ)whichcanbeusedtoachievelhefullapproximationorderofS82(Δ)anditscardinalilyislessthanthedi-mensionofsupersplinespacespaceS82(Δ).

  • 标签: spline TRIANGULATION triangle collection SMOOTHNESS vertex
  • 简介:我们在场这里周期的oligo(乙烯adipate)的第一合成经由有乙烯乙二醇的adipoyl氯化物的伪高度冲淡冷凝作用反应的s(COEA),和合成相应poly(乙烯adipate)(豌豆)经由COEA的melt聚合。COEA的结构被1H-NMR和MALDI-TOF团大小。器官的底,反应温度和到COEA的收益上的乙烯乙二醇的adipoyl氯化物的比率的效果被学习,并且最佳反应条件被揭示。豌豆,二酸和diol基于半水晶的绿脂肪族的聚酯,被COEA的melt聚合用Ti综合(n-C4H9O)是的4是的催化剂和1,10-decanediol在200点的开始者在上到葡萄牙的语言的BPI在巴西说瞄准它的以后的用法在癌症病人生活测量疼痛的紧张和干扰。方法:BPI-B从原来的位/英寸被开发,用背翻译和委员会评论。背Translatio?

  • 标签: 二酸乙二醇酯 聚合合成 熔融聚合 POLY 环状 脂肪族聚酯
  • 简介:Thecombustionperformanceoftheboilerlargelydependsonthecoaltype.Lotsofexperimentalresearchshowsthatdifferentfuelshavedifferentcombustioncharacteristics.ItisobviousthatfuelwillchangethewholeoperatingperformanceofCirculatingFluidizedBedCombustion(CFBC).Weknoweveninapilot-scalerunningboiler,themeasurementofsomeparametersisdifficultandcostly.Therefore,wedevelopedthewayofsimulationtoevaluatethecombustionperformanceofChinesecoalsinCFB,Thesimulationresultsshowthat,differentcoalswillresultindifferentcoalparticlediameterandcominutiondependingontheirmineralcomponentandthechangewillaffectthedistributionofashinCFBCsystem.Inaword.thecomputationalresultsareinaccordancewithexperimentalresultsqualitativelybuttherearesomedifferencesquantitatively.

  • 标签: 锅炉 燃烧 CFB 循环流化床 模拟
  • 简介:Inthispaperweobtainthebestapproximationconstantoffunctionf(x)(∈C2π)bytheJackson’stypeoperatorJπ3(f;x),i.e.‖Jn,3(f,x)-f(x)‖c≤(4-6/π)ω(f,1/n),‖Jn,3(f,x)-f(x)‖c≤(8-17/π)ω2(f,1/n)

  • 标签: umber EQUALITY INTEGER 刁刀 DERIVE OPERA
  • 简介:在吝啬地的三地点的BoseHubbard模型以内,偶极的bosonic气体与的通道动力学一周期性地,散布的s波浪的调整被调查。系统经历通道(CDT)的协调破坏转移在下邻居偶极子偶极子相互作用,所在地的相互作用和散布的调制s波浪之中源于相关效果的复杂、富有的协调通道(CT)。特别地,为产生CT(CDT)散布的调制s波浪的区域是最宽(最狭窄)什么时候所在地的相互作用和下邻居偶极子偶极子相互作用一些相关与通道精力和系统的相互作用精力有关仔细珍视,它是。为出现CDT的相关的值能理论上从通道精力和系统的相互作用精力被获得。

  • 标签: 偶极相互作用 周期性调制 玻色系统 隧道掘进 波散射 HUBBARD模型
  • 简介:在这份报纸,我们使用任意的Riemann解答者,它不能满足Maire的要求,到Maire发展在的基于节点的Lagrangian计划[P.H。Maire等,暹罗J。Sci。Comput,29(2007),1781-1824]。特别地,我们使用所谓的多液体隧道onAveraged体积(MFCAV)Riemann解答者和适应地把MFCAV解答者与另外的更消散的Riemann解答者相结合到Maire的计划的一个Riemann解答者。任何一个二个解答者都不满足Maire的要求,这被注意。数字实验被介绍证明二个Riemann解答者的应用程序是成功的。[从作者抽象]

  • 标签: 拉格朗日法 求解器 黎曼 应用 作者 体育发展
  • 简介:ThechoicenumberofagraphG,denotedbyX1(G),istheminimumnumberksuchthatifalistofkcolorsisgiventoeachvertexofG,thereisavertexcoloringofGwhereeachvertexreceivesacolorfromitsownlistnomatterwhatthelistsare.Inthispaper,itisshowedthatX1(G)≤3foreachplanegraphofgirthnotlessthan4whichcontainsno6-,7-and9-cycles.

  • 标签: 平面图 二部图 EULER公式 可选择性