简介:摘要:在人类历史的长河中,建筑只是被动地抵御寒冷。工业革命以后,各种新型建筑材料的应用,以及采暖通风和空调设备的普及,使人们享受着四季如春的室内环境。但是这种享受是建立在消耗大量的不可再生能源,以及排放有害气体的基础之上的。
简介:摘要:隧道施工是城市网络交通通行保障中的重要的一部分,而盾构机作为一种安全且有时效性的隧道掘进机械,在隧道推进种中得到了大范围的应用。由于上海市城市道路中心受各方面外部条件的制约,在市区的作业环境下基本采用上下层隧道设计,因此盾构机在南、北两个工作井先后下井吊装时存在高差,本文旨在探讨隧道项目中盾构设备下井吊装施工的技术要点,为相关工程提供参考。
简介:IsothermalcompressionofaTi-5.6Al-4.8Sn-2.0ZralloywasconductedonaThermecmaster-Zsimulatoratthedeformationtemperaturesrangingfrom960to1060°C,thestrainratesrangingfrom0.001to10.0s-1,andthemaximumheightreductionof70.0%.Inthetwo-phaseregionoftheTi-5.6Al-4.8Sn-2.0Zralloy,thevolumefractionofαphasedecreaseswithanincreaseindeformationtemperature,butthegrainsizehasaslightvariationwithdeformationtemperature.ThestrainrateaffectsbothmorphologiesandgrainsizeoftheαphaseintheisothermalcompressionoftheTi-5.6Al-4.8Sn-2.0Zralloy.Theoptimalheightreductionalsocontributestothesmallandwell-distributedαphaseintheisothermalcompressionofTi-5.6Al-4.8Sn-2.0Zralloy.
简介:
简介:Sn-dopedTiO_2nanoparticleswithhighsurfaceareaof125.7m~2·g~(-1)aresynthesizedviaasimpleone-stephydrothermaimethodandexploredasthecathodecatalystsupportforprotonexchangemembranefuelcells.ThesynthesizedsupportmaterialsarestudiedbyX-raydiffractionanalysis,energydispersiveX-rayspectroscopyandtransmissionelectronmicroscopy.Itisfoundthattheconductivityhasbeengreatlyimprovedbytheadditionof30mol%SnandPtnanoparticlesarewelldispersedonTi_(0.7)Sn_(0.3)O_2supportwithanaveragesizeof2.44run.ElectrochemicalstudiesshowthattheTi_(0.7)Sn_(0.3)O_2nanoparticleshaveexcellentelectrochemicalstabilityunderahighpotentialcomparedtoVulcanXC-72.Theas-synthesizedPt/Ti_(0.7)Sn_(0.3)O_2exhibitshighandstableelectrocatalyticactivityfortheoxygenreductionreaction.ThePt/Ti_(0.7)Sn_(0.3)O_2catalystreservesmostofitselectrochemicallyactivesurfacearea(ECA),anditshalfwavepotentialdifferenceis11mV,whichislowerthanthatofPt/XC-72(36mV)under10hpotentialholdat1.4Vvs.NHE.Inaddition,theECAdegradationofPt/Ti_(0.7)Sn_(0.3)O_2is1.9timeslowerthancommercialPt/XC-72under500potentialcyclesbetween0.6Vand1.2Vvs.NHE.Therefore,theassynthesizedPt/Ti_(0.7)Sn_(0.3)O_2canbeconsideredasapromisingalternativecathode,catalystforprotonexchangemembranefuelcells.
简介:【摘要】目的:研究分析超声TI-RADS分级对甲状腺癌的临床诊断应用。方法:研究对象为2010年1月至2021年2月到我院就诊的
简介:采用电磁悬浮方法,通过原位观察再辉曲线进行过冷Ti-46Al-7Nb亚包晶合金的快速凝固研究,获得的最大过冷度为240K。在一定过冷度下对悬浮的熔体进行铜基底悬淬,进而对凝固合金的微观组织进行分析。超过一定的临界过冷度(ΔT*=205K),凝固模式将从具有包晶转变特征向包晶转变被抑制转化。当熔体初始过冷度ΔT≤ΔT*时,遵循包晶合金的典型凝固规律,β相作为初生相析出,在随后的冷却过程中包晶相α以包晶反应、包晶转变的方式析出。当ΔT〉ΔT*时,β相直接凝固,包晶相α的析出被抑制。包晶反应能否发生取决于包晶相α的孕育时间τP与再辉后熔体完全β相凝固所需的时间tβ的相对大小。当过冷度相差不大时,通过改变凝固过程的冷速,组织中获得β相向α"相的马氏体转变。