简介:Theseaicecoverdisplaysvariousdynamicalcharacteristicssuchasbreakup,rafting,andridgingunderexternalforces.Tomodeltheicedynamicprocessaccurately,theeffectivenumericalmodelingmethodshouldbeestablished.Inthispaper,amodifiedparticle-in-cell(PIC)methodforseaicedynamicsisdevelopedcouplingthefinitedifference(FD)methodandsmoothedparticlehydrodynamics(SPH).Inthismethod,theicecoverisfirstdiscretizedintoaseriesofLagrangianiceparticleswhichhavetheirownsizes,thicknesses,concentrationsandvelocities.TheicethicknessandconcentrationatEuleriangridpositionsareobtainedbyinterpolationwiththeGaussianfunctionfromtheirsurroundingiceparticles.ThemomentumoficecoverissolvedwithFDapproachtoobtaintheEuleriancellvelocity,whichisusedtoestimatetheiceparticlevelocitywiththeGaussianfunctionalso.Thethicknessandconcentrationoficeparticlesareadjustedwithparticlemassdensityandsmoothlength,whichareadjustedwiththeredistributionoficeparticles.WiththeabovemodifiedPICmethod,numericalsimulationsforicemotioninanidealizedrectangularbasinandtheicedynamicsintheBohaiSeaarecarriedout.ThesesimulationsshowthatthismodifiedPICmethodisapplicabletoseaicedynamicssimulation.
简介:ItisnecessaryforanMC-CDMAuplinkreceivertoemployMUD(multiuserdetection)inafrequencyselectivefadingchannel.AfteranalyzingthealgorithmofPIC(parallelinterferencecancellation)MUD,anovelMUDscheme,Soft-PIC(softparallelinterferencecancellation)isproposed.Basedonthereliabilityofeachdetectedusersignalintheformerstage,thisSoft-PICdetectionschemesubstitutesasoftdecisionofthevariablefortheharddecisioninPICscheme.ComparedwiththePICscheme,itcanreconstructtheinterferencesignalsmoreaccuratelyandeliminateMAI(multipleaccessinterference)inamoreefficientway.PICisoneofthemostpracticalschemesinnumerousmultiuserdetectiontechnologies.However,Soft-PICasanimprovedPICschemedeservesfurtherstudy.
简介:MicrochipTechnology(美国微芯科技公司)推出配备多种外设的通用闪存PIC单片机,有助于实现更具成本效益的风扇或小型电机控制。全新14引脚PIC16F616/610和8引脚PIC12F615/609单片机集成了多种专用外设,可大大减少系统所需的元件,降低成本。这些外设包括具有死区控制的全桥脉宽调制(PWM)、用于脉宽测量的Timerl门、霍尔效应传感器接口比较器,以及具有温度和其他监控功能的数/模转换器。同系列器件PIC16HV616/610和PIC12HV615/609增加了内置分流稳压器,使PIC单片机无需另加稳压器就可以在更高电压轨上运行。