简介:Inconsideringthetheoryofstructuraldynamicoptimizationdesign,adesignmethodofthestructuralstyleofshipcompositebracewithrigidvibrationisolationmasswasstudied.Twokindsofstructuraldynamicoptimizationformulationsminimizingthevibrationaccelerationofthenon-pressurehullontherestrainingconditionofthegrossweightoftheshipcabinwereestablished:1)dynamicoptimizationofthesectionaldimensionsoftherigidvibrationisolationmassinthecompositebrace;2)dynamicoptimizationofthearrangingpositionoftherigidvibrationisolationmass.Throughtheoptimizationresults,sectionaldimensionsandthearrangingpositionoftherigidvibrationisolationmasswithbetterperformanceinreducingvibrationweregained,andsomereferencewasprovidedforpracticalengineeringdesignsaswellasenrichmentofthedesignmethodofanovelshipvibration-isolationbrace.
简介:Rigidblockingmassesarelocatedinthetypicalbasestructureofapowercabinbasedontheimpedancemismatchprinciple.Bycombiningtheacoustic-structuralcouplingmethodandstatisticalenergyanalysis,thefull-bandvibrationandsoundradiationreductioneffectofvibrationisolationmasseslocatedinabasestructurewasresearched.Theinfluenceoftheblockingmass’cross-sectionsizeandshapeparametersandthelayoutlocationofthebaseisolationperformancewasdiscussed.Furthermore,theeffectivenessofrigidvibrationisolationdesignofthebasestructurewasvalidated.Theresultsshowthatthemediumandhighfrequencyvibrationandsoundradiationofapowercabinareeffectivelyreducedbyablockingmass.Concerningweightincrementandsectionrequirement,suitablyincreasingtheblockingmasssizeandsectionheightandreducingsectionwidthcanresultinanefficiency-costratio.
简介:OnMarch26,2010anunderwaterexplosion(UWE)ledtothesinkingoftheROKSCheonan.TheofficialMultinationalCivilian-MilitaryJointInvestigationGroup(MCMJIG)reportconcludedthatthecauseoftheunderwaterexplosionwasa250kgnetexplosiveweight(NEW)detonationatadepthof69mfromaDPRK'CHT-02D'torpedo.KimandGitterman(2012a)determinedtheNEWandseismicmagnitudeas136kgatadepthofapproximately8mand2.04,respectivelyusingbasichydrodynamicsbasedontheoreticalandexperimentalmethodsaswellasspectralanalysisandseismicmethods.ThepurposeofthisstudywastoclarifythecauseoftheUWEviamoredetailedmethodsusingbubbledynamicsandsimulationofpropellersaswellasforensicseismology.Regardingtheobservedbubblepulseperiodof0.990s,0.976sand1.030swerefoundincaseofa136NEWatadetonationdepthof8musingtheboundaryelementmethod(BEM)and3Dbubbleshapesimulationsderivedfora136kgNEWdetonationatadepthof8mapproximately5mportsidefromthehullcenterline.Hereweshowthroughanalyticalequations,modelsand3Dbubbleshapesimulationsthatthemostprobablecauseofthisunderwaterexplosionwasa136kgNEWdetonationatadepthof8mattributabletoaROKlittoral'landcontrol'mine(LCM).
简介:介绍了一种基于Spalding公式拟合的脊状表面减阻测试方法,相比于用天平等测力设备测试的方法,其优点在于简便实用,从应用实例来看,准确性也是令人满意的.由于该方法依靠的数据基础是壁面边界层内层速度分布,因此,速度分布测量的准确程度是影响该方法测试结果准确与否的决定因素.
简介:由于跨江桥梁钢箱梁吊装工艺的特殊性,施工过程中对水域通航产生碍航,为避免产生船舶碰撞事故,本文以虎门二桥所跨坭洲桥梁处为横截面的船舶AIS数据为基础,针对桥梁建设中的水上交通环境在时间上划定阶段性、在空间上划定区块性进行分析,针对性提出临时交通管制、推荐航路航道转换等面向水上交通风险的对策.研究成果为海事监管部门提供了实践性指导意见,减小了对桥梁周围水域航行船舶碍航性及降低警戒力量的投入,所提出的移动安全作业区、航路转换、合理布置警戒力量等通航安全保障措施以期为同类施工作业提供基于情景案例的实践参考.