简介:研究了一类用于时间序列建模的混合自回归滑动平均模型,该模型是由m个ARMA分量经过混合得到的,给出了混合自回归滑动平均模型参数估计的期望极大化(EM)算法,从而得到了混合系数和分量模型的参数,通过仿真说明了其有效性。
简介:Theground-stateandthermodynamicpropertiesofquantummixed-spinchainsof1/2-1/2-1-1and3/2-3/2-1-1areinvestigatedbyaquantumMonteCarlosimulationwiththeloop-clusteralgorithm.For1/2-1/2-1-1chain,wefindithastwophasesseparatedbyanenergy-gapvanishingpointintheground-state.For3/2-3/2-1-1chain,thenumericalresultsshowtwoenergy-gapvanishingpointsisolatedbydifferentphasesinitsground-state.Ourcalculationsindicatethatallthesegroundstatephasescanbeunderstoodbymeansofvalence-bond-solidpicture,andthethermodynamicbehavioratfinitetemperaturesiscontinuousasafunctionofparameterα=J2/J1.
简介:利用压力传感器测量扑翼的瞬时力,利用数字粒子测速仪(digitalparticleimagevelocimetry,DPIV)系统测量扑翼的前缘涡以及周围的流场,来揭示前缘涡在不同间距下对扑翼平均推力的影响.实验在-个低Reynolds数循环水洞中进行,两串列扑翼均做二维正弦平动.在固定的相位差下,当间距增加时,后翅前缘涡对前翅的影响具有相似性,均提高或者均降低前翅的平均推力.前翅平均推力的提高是由于后翅的前缘涡提高了前翅尾部的射流速度以及有效攻角.随着间距的增加,后翅前缘涡对前翅的影响急剧下降,使得前翅的平均推力快速接近于单翼值.在固定的相位差下,当间距增加时,前翅的脱落涡对后翅的影响变化非常大,后翅的平均推力可能先升高后降低,这是因为间距改变了前翅脱落涡作用于后翅的时间点.当前翅脱落涡遇到后翅,并且和后翅的前缘涡有相同的旋转方向时,前翅的脱落涡会抑制后翅前缘涡的形成,并且后翅的有效攻角减小,其平均推力降低.如果这两个涡的旋转方向相反,那么后翅有效攻角就会增大,平均推力值就会提高.
简介:6,9,11-Trihydroxy-6a,12a-dehydrorotenoid1(coccineoneB)wassynthesizedfrom2-hydroxybenzaldehyde2andphloroglucinol.
简介:ElectrochemicalBettednotonlycanobtaintheconductingfilmofpolyanilineonaglasscarbonelectrode,butalsocanimobilizePMo12O403-inthefilmtoformaorganicconductingfilmelectrodemodifiedbyheteropolyanion.ThepaperherereportselectrochemicalchangesinthepreparationofPMo12O403--polyanilinemodifiedelectrode,theelectrochemicalreactionmechanismofthemodifiedelectrodewasobtainedfromthestudyonitsredoxproperties.Moreover,theaboveelectrodeshowedmarkedelectrocatalysisforthereductionreactionofCIO?-.
简介:TheimmunomodulatingeffectsofF12onmouseperitonealmacroplhageswasintendedtobestudiedwithdifferentdosesof20,40,80,and120mg/Kg.F12increasedperoxidaseactivityindexcdependentmammerfrom0.02±0.001,to0.175±0.038,0.211±0.041,0.137±0.045and0.078±0.036,respectively,increasedcytotoxicityfrom127.33±22.96to162.74±19.53,237.30±25.15,178.62±36.22and158.66±42.75dpm,respectively,promotedphagocyticactivityfrom0.03±0.01to0.21±0.016,0.43±0.041,0.40±0.032and0.30±0.160^b,Furthermore,F12inaconcentrationof15,30,60,120ug/mlenhancedIL-1productionfrom0.15±0.02to0.20±0.005^b0.21±0.02,0.22±0.005,0.24±0.002and0.22±0.02,respectively,ThusF12canbeconsideredasaneffectivestimulatorofmacrophages.