简介:Ananalyticalstudywaspresentedonactivecontrolofsoundtransmissionintoavibro-acousticenclosurecomprisingtwoflexibleplates.Twotypesofactuatorswereused,i.e.acousticactuatoranddistributedleadzirconatetitanatepiezoelectric(PZT)actuatorinsteadofpointforceactuator.Usingthemodalacoustictransferimpedance-mobilitymatrices,theexcitationandinteractioninthecoupledsoundtransmissionsystemcanbedescribedwithclearphysicalsignificance.Withthecontrolsystemdesignedtogloballyreducethesoundfield,differentcontrolsystemconfigurationswereconsidered,includingthestructuralactuatorontheincidentplate,actuatoronthereceivingplate,acousticactuatoronthecavity,andtheircombinations.Theeffectivenessandperformanceofthecontrolstrategycorrespondingtoeachsystemconfigurationwerecomparedanddiscussed.Theroleandcontrolmechanismofeachtypeofactuatorwereofparticularinterest.Itwasshownthattheincidentplateactuatoriseffectiveincontrollingthecavity-dominatedmodesandthestructuralmodesdominatedbytheincidentplateandreceivingplate.Twomaincontrolmechanismsareinvolvedinthiscontrolconfiguration,i.e.,modalsuppressingandmodalrearrangement.Forcontrolsystemconfigurationwithonlyacousticactuatorintheenclosure,themechanisminvolvedinthisarrangementispurelymodalsuppression.Desirableplacementsofstructuralactuatorsintermsoftotalpotentialenergyreductionwerealsodiscussed.
简介:针对STCW公约马尼拉修正案履约过渡期船员教育和培训工作,从中国海事局下发的"关于印发《STCW公约马尼拉修正案过渡规定实施办法》的通知"等对航海培训机构的要求和影响进行分析,提出履约过渡期的应对策略。
简介:从理论上分析海事电子产品销售网络和售后服务网络的重要性、多样性和销售网络建立的原则、目标。深入分析成功案例(AISClassA船载应答机的销售和售后服务网络建立及策略),其中内容主要包括产品市场容量、产品销售的特点、建立产品销售网络的战略意义、销售网络构架、销售网络机构职责、开发销售网络的策略、建立售后服务网络的分析,将理论用于实践,从实践中总结理论。