简介:摘要双向AC-DC变换器作为交直流混合微电网的重要组成部分,对系统的稳定运行和功率的协调分配有着重要作用。本文基于切换系统理论,提出一种双向AC-DC切换控制方法。该方法首先建立双向AC-DC切换动态模型,选取系统的储能函数作为共同Lyapunov函数。基于此,设计了系统最优切换律并分析了该切换律条件下系统在切换平衡点处的稳定性。为了便于控制器数字化实现,建立了切换系统单步预测模型并对切换策略离散化。仿真和实验结果验证了本文所采用的建模方法和控制策略的有效性。
简介:TheAl-alloyarc-weldingshapingsystembasedonarc-weldingrobotisestablished,andtheAl-alloyshapingmanufactureisrealizedwiththeDC(directcurrent)gasmetalarcwelding(GMAW).TheresearchindicatesthatthemetaltransfertypeofDCGMAW,heatinputandtheinitialtemperatureoftheworkpiecegreatlyaffecttheAl-alloyshapingbasedonarcweldingrobot.Onthepenetration,theweldwidthandthereinforcement,theinfluenceofweldingparametersisanalyzedbygeneralizedregressionneuralnetwork(GRNN)fitting.
简介:查干凹陷火山岩储集层主要为孔洞-裂缝或裂缝-孔洞型,为典型的特殊油气藏储集层,在火山岩钻探过程中,由于井壁垮塌非常普遍,井径扩大率较大,使得声波时差、密度等测井资料失真,造成利用测井资料识别火山岩储集层困难,而综合录井参数具有不受井径扩大影响的特点。火山岩储集层孔隙度与可钻性的相关性分析表明,两者线性相关(r^2=0.845);dc指数随孔隙度的增大而减小,当dc指数小于1.85时,孔隙度值达到11%以上,为有利储集层区。实践表明,dc指数较小的区域储集层发育,油气显示富集,反之储集层物性较差,应用dc指数法进行火山岩储集层识别与评价取得了较好效果。
简介:AluminumfilmscoatedonDIsteelsheetswerepreparedbydirectcurrent(DC)magnetronsputtering.Theinfluenceofthedepositionconditionsandfilmthicknessontheformabilityofcoatedsteelsheetswasstudied.TheresultsofthecuppingtestanddrawingtestshowthatthesubstratetemperatureandthicknessofAlfilmsarethekeyfactorsthataffectAladhesionandformabilityofcoatedsteelsheets.AdhesionbecameworsewhenthethicknessofAlsheetswasmorethan2μm.Andformabilitywasimprovedremarkablywhenthesubstratetemperaturewasincreasedto200℃.
简介:Thispaperproposesanewmethodtopredictthecoronaonsetvoltageforarodplaneairgap,basedonthesupportvectormachine(SVM).BecausetheSVMisnotlimitedbythesize,dimensionandnonlinearityofthesamples,thismethodcanrealizeaccuratepredictionwithfewtrainingdata.Onlyelectricfieldfeaturesarechosenastheinput;nogeometricparameterisincluded.Therefore,theexperimentdataofonekindofelectrodecanbeusedtopredictthecoronaonsetvoltagesofotherelectrodeswithdifferentsizes.Withtheexperimentaldataobtainedbyozonedetectiontechnology,andexperimentaldataprovidedbythereference,theefficiencyoftheproposedmethodisvalidated.Accuratepredictedresultswithanaveragerelativelessthan3%areobtainedwithonly6experimentaldata.
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简介:虽然AMD公司近几年的发展速度让英特尔公司备感压力.但AMD在笔记本电脑平台上给对手的压力远没有DIY市场上明显.在笔记本电脑平台上,英特尔还是绝对的王者。究其原因.正是因为相对于英特尔集成处理器.无线网卡和显卡的迅驰计算平台,AMD的处理器显出了单兵作战的势单力薄。为了改变这种尴尬境地,AMD在近日推出了白金汉平台。”BetterbyDesign”计划,俗称白金汉,AMD的这个平台构成和迅驰平台不同.其包括AMD的处理器.ATi或nVIDIA显卡和Broadcom.Airgo、Atheros、RealTek等的无线网卡三部分,
简介:Aneworganicsemiconductortartaricaciddopedsaltofemeraldinepolyaniline(PANI-C4H6O6)hasbeenobtainedbythemethodofoxidativepolymerizationofmonomericanilinewithammoniumpersulfateinacidicsolution.ThestructurewascharacterizedbyFourierTransformInfraredtechnique(FTIR)andX-raydiffraction(XRD).Thetemperaturedependencedcconductivityδdc(T)showsasemiconductorbehaviorandfollowsthequasionedimensionalvariablerangehopping(Q1D-VRH)model.Dataonδdc(T)arealsodiscussed.