简介：2004年12月20日晚7点。清华大学东门外的学研大厦三层多功能厅门外．三五成群的年轻人越聚越多．这些时常游走于水木清华BBS的清华网虫们．都是为了观看一部水木清华DV爱情故事的贺岁首映而赶来的。

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简介：Thepaperpresentsthreeformalprovingmethodsforgeneralizedweaklygroundterminatingproperty,i.e.,weaklyterminatingpropertyinarestricteddomainofatermrewritingsystem,onewithstructuralinduction,onewithcover-setinduction,andthethirdwithoutinduction,anddescribestheirmechanizationbasedonameta-computationmodelfortermrewritingsystems-dynamictermrewritingcalculus.Themethodscanbeappliedtonon-terminating,nonconfluentand/ornon-left-lineartermrewritingsystems.Theycando"forwardproving"byapplyingpropositionsintheproof,aswellas"backwardproving"bydiscoveringlemmasduringtheproof.

简介：Thispaperproposesanewasymptoticattitudetrackingcontrollerforanunderactuated3-degree-of-freedom（DOF）laboratoryhelicoptersystembyusinganonlinearrobustfeedbackandaneuralnetwork（NN）feedforwardterm.Thenonlinearrobustcontrollawisdevelopedthroughamodifiedinner-outerloopapproach.TheapplicationoftheNN-basedfeedforwardistocompensateforthesystemuncertainties.Theproposedcontroldesignstrategyrequiresverylimitedknowledgeofthesystemdynamicmodel,andachievesgoodrobustnesswithrespecttosystemparametricuncertainties.ALyapunov-basedstabilityanalysisshowsthattheproposedalgorithmscanensureasymptotictrackingofthehelicopter＇selevationandtravelmotion,whilekeepingthestabilityoftheclosed-loopsystem.Real-timeexperimentresultsdemonstratethatthecontrollerhasachievedgoodtrackingperformance.