简介：Theultrafastchargedynamicsfollowingtheinteractionofanultra-intenselaserpulsewithafoiltargetleadstothelaunchofanultra-short,intenseelectromagnetic（EM）pulsealongawireconnectedtothetarget.Duetothestrongelectricfield（oftheorderofGVm^-1）associatedtosuchlaser-drivenEMpulses,thesecanbeexploitedinatravelling-wavehelicalgeometryforcontrollingandoptimizingtheparametersoflaseracceleratedprotonbeams.ThepropagationoftheEMpulsealongahelicalpathwasstudiedbyemployingaprotonprobingtechnique.Thepulse-carryingcoilwasprobedalongtwoorthogonaldirections,transverseandparalleltothecoilaxis.Thetemporalprofileofthepulseobtainedfromthetransverseprobingofthecoilisinagreementwiththepreviousmeasurementsobtainedinaplanargeometry.Thedataobtainedfromthelongitudinalprobingofthecoilshowsaclearevidenceofanenergydependentreductionoftheprotonbeamdivergence,whichunderpinsthemechanismbehindselectiveguidingoflaser-drivenionsbythehelicalcoiltargets.

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。