简介:SeveralARMAmodelingapproachesareaddressed.Inthesemethodsonlypartofacorrelationsequenceisemployedforestimatingparameters.Itissatisfying,ifthegivencorrelationsequenceisofrealARMA,sinceanARMAprocesscanbecompletelydeterminedbypartofitscorrelationse-quence.Butforthecaseofameasuredcorrelationsequencethewholesequencemaybeusedtore-ducetheeffectoferroronmodelparameterestimation.Inaddition,thesemethodsnowdonotguar-anteeanonnegativespectralestimate.Inviewoftheabove-mentionedfact,aconstrainedleastsquaresfittingtechniqueisproposedwhichutilizesthewholemeasuredcorrelationsequenceandguar-anteesanonnegativespectralestimate.
简介:Stochasticadaptivecontrolisconsideredforthediscrete-timemulti-inputandmulti-outputsystemofmulti-delaywithnoiseexpressedbyanARMAprocess.TheCARIMAmodelisaspecialcaseofthesysteminquestion.Theoptimaladaptivecontrollawisgivenanditisshownthataquadraticcostfunctionisminimizedandtheclosed-loopsystemisstable.Further,whenthesystemisofminimumphase,theconvergenceratesofparameterestimatesandofthecost-functionarealsoderived.
简介:Atimeseriesx(t),t≥1,issaidtobeanunstableARMAprocessifx(t)satisfiesanunstableARMAmodelsuchasx(t)=a1x(t-1)+a2x(t-2)+…+a8x(t-s)+w(t)wherew(t)isastationaryARMAprocess;andthecharacteristicpolynomialA(z)=1-a1z-a2z2-…-a3z3hasallrootsontheunitcircle.Asymptoticbehaviorofsumform1ton(x2(t))willbestudiedbyshowingsomeratesofdivergenceofsumform1ton(x2(t)).ThiskindofpropertiesWillbeusedforgettingtheratesofconvergenceofleastsquaresestimatesofparametersa1,a2,…,a?
简介:NUK儿童安全牙膏德国品质无氟温和配方,有效保护宝宝牙龈与牙齿本品为婴幼儿专用配方,不含氟、刺激性SLS、麸质、糖和人工甜昧剂,温和无刺激。保护宝宝萌出的第一颗小乳牙,温和清洁宝宝口腔。含木糖醇和维生素E,有效营养牙龈并预防蛀牙,清新的苹果香蕉味,让宝宝不抗拒刷牙。德国制造,原装进口,符合欧盟与国标标准。经典升级非同以往植村秀全新如胶似漆眼线笔2013年.植村秀推出第一款具有划时代意义的笔状眼线胶.并以其柔滑如胶、浓郁似漆的特点在眼线市场上拔得头筹。2017年。如胶似漆
简介:Basedonthemulti-sensoroptimalinformationfusioncriterionweightedbymatricesinthelinearminimumvariancesense,usingwhitenoiseestimators,anoptimalfusiondistributedKalmansmootherisgivenfordiscretemulti-channelARMA(autoregressivemovingaverage)signals.Thesmoothingerrorcross-covariancematricesbetweenanytwosensorsaregivenformeasurementnoises.Furthermore,thefusionsmoothergiveshigherprecisionthananylocalsmootherdoes.
简介:目的探讨应用时间序列ARMA模型对甲肝发病趋势进行预测的可行性,为预防和控制甲肝提供依据。方法采用SPSS13.0对中山市2004-2009年的甲肝月发病人数资料建立ARMA模型,并对2010年上半年数据进行2步递推预测,通过对拟合残差的白噪声检验评价模型的拟合效果,采用绝对误差百分比、均方根误差评价预测效果。结果AR(1)是拟合中山市2004-2009年甲肝逐月发病数较为合适的模型,模型为yt=5.137+0.435yt-1+at,其AR1系数为0.435(t=4.026,P〈0.001);模型拟合残差的自相关系数和偏相关系数在不同时刻均无统计学意义,Ljung-BoxQ统计量差异无统计学意义(Q=6.609,P=0.636),残差检验符合白噪声,模型拟合效果良好;绝对误差百分比和均方根误差分别为0.029和0.856,预测效果良好。结论AR(1)模型能较好的模拟中山市甲肝发病情况,且能较好地预测未来短期内的发病趋势。
简介:StatisticalpropertiesofwindsneartheTaichungHarbourareinvestigated.The26years′incompletedataofwindspeeds,measuredonanhourlybasis,areusedasreference.ThepossibilityofimputationusingsimulatedresultsoftheAuto-Regressive(AR),Moving-Average(MA),and/orAuto-RegressiveandMoving-Average(ARMA)modelsisstudied.Predictionsofthe25-yearextremewindspeedsbasedupontheaugmenteddataarecomparedwiththeoriginalseries.Basedupontheresults,predictionsofthe50-and100-yearextremewindspeedsarethenmade.