简介:摘要飞机的起落架系统为飞机在地面停放和操作时提供支撑作用。起落架系统包括两个主起落架和一个前起落架。本文主要介绍了B737的起落架系统、系统部件,一些实例故障分析和维护方法,对B737的起落架系统有更深的了解。
简介:High-frequencystocktrendpredictionusingmachinelearnershasraisedsubstantialinterestinliterature.Nevertheless,thereisnogoldstandardtoselecttheinputsforthelearners.Thispaperinvestigatestheapproachofadaptiveinputselection(AIS)forthetrendpredictionofhigh-frequencystockindexpriceandcomparesitwiththecommonlyuseddeterministicinputsetting(DIS)approach.TheDISapproachisimplementedthroughcomputationoftechnicalindicatorvaluesondeterministicperiodparameters.TheAISapproachselectsthemostsuitableindicatorsandtheirparametersforthetime-varyingdatasetusingfeatureselectionmethods.Twostate-of-the-artmachinelearners,supportvectormachine(SVM)andartificialneuralnetwork(ANN),areadoptedaslearningmodels.AccuracyandF-measureofSVMandANNmodelswithboththeapproachesarecomputedbasedonthehigh-frequencydataofCSI300index.TheresultssuggestthattheAISapproachusingt-statistics,informationgainandROCmethodscanachievebetterpredictionperformancethantheDISapproach.Also,theinvestmentperformanceevaluationshowsthattheAISapproachwiththesamethreefeatureselectionmethodsprovidessignificantlyhigherreturnsthantheDISapproach.
简介:摘要:近年来我国风电厂建设规模提升较快,风电厂的安全运行对于风电能源的使用具有直接影响。本文从风电机组雷击破坏原理和具体形式分析入手,探讨了风电机组防雷保护的原则与具体措施。
简介:利用信息技术实现水电机组的状态监测和故障诊断是提高水电厂经济效益和安全运行的重要技术保证。本文重点介绍了水电机组状态监测和故障诊断系统及其经济效益和成功案例。