简介:以港珠澳大桥钢桥面铺装为研究背景,采用3种沥青含量,分析沥青含量变化对GMA浇注式沥青混凝土的施工和易性、高温稳定性、疲劳性能的影响。研究表明:流动度随沥青含量的增加而减小;沥青含量对其路用性能影响显著。研究成果可为其它类似桥面铺装质量控制提供较好的借鉴。
简介:Inordertostudytheeffectsofgeometricparametersoftherudderonthehydrodynamicperformanceofthepropeller-ruddersystem,thesurfacepanelmethodisusedtobuildthenumericalmodelofthesteadyinteractionbetweenthepropellerandruddertoanalyzetherelevantfactors.Theinteractionbetweenthepropellerandrudderisconsideredthroughtheinducedvelocities,whicharecircumferentiallyaveraged,sotheunsteadyproblemistranslatedtosteadystate.Aniterativecalculationmethodisuseduntilthehydrodynamicperformanceconverges.Firstly,thehydrodynamicperformanceofthechosenpropeller-ruddersystemiscalculated,andthecomparisonbetweenthecalculatedresultsandtheexperimentaldataindicatesthatthecalculationprogramisreliable.Then,thevariableparametersofrudderareinvestigated,andthecalculationresultsshowthatthepropeller-rudderspacinghasanegativerelationshipwiththeefficiencyofthepropeller-ruddersystem,andtherudderspanhasanoptimalmatchrangewiththepropellerdiameter.Futhermore,therudderchordandthicknessbothhaveapositivecorrelationwiththehydrodynamicperformanceofthepropeller-ruddersystem.
简介:针对708研究所自主研发的科研设计管理信息系统,应用SQL优化技术、数据查询访问优化技术和高级优化技术等方法,就单表检索及表间检索两方面展开优化研究,得到了可以适用于一般信息管理系统的指导性方法。