排序方式: 共有48条查询结果,搜索用时 31 毫秒
31.
奎先运营隧道射流通风效果的卫生学评价 总被引:2,自引:0,他引:2
目的 摸清当前车流密度下不同运营状态,自然及机械通风排烟效果,同时探索不同给风时间对排烟效果的影响。项目 在奎先隧道内进行空气中C0、N0x、C02,02的测定。结果 射流式通风的排烟效果明显优于自然通风,试验提前通风与列车上行出洞后实施机械通风较为合适。结论 奎先运营隧道射流通风效果基本达到通风设计要求。 相似文献
32.
用裂尖强度极限作为临界条件,给出了计算裂纹扩展寿命的算式,为确定大型港口机械金属结构件的巡检周期提供了科学依据。 相似文献
33.
叙述了使用中的趸船因生产需要而设置起重机基础时的多种方案,讨论了起重机因吨位的增加而需要加固时的设计方案和实施方法,同时指出施工中应保证船体结构整体性。 相似文献
34.
大型沥青砼摊铺机液压自动调平回路分析 总被引:2,自引:0,他引:2
沥青砼摊铺机是当前高等级沥青路面施工中的重要机械,其液压自动调平回路的性能对路面的平整度有着重要影响.文中简要介绍了沥青砼摊铺机自动调平回路的工作原理,分析、比较了国内外几种大型沥青砼摊铺机的自动调平液压回路的特点,简要论述了当前沥青砼摊铺机自动调平系统的最新进展. 相似文献
35.
目的 研究中国男性群体中D-氨基酸氧化酶激活剂(DAOA)基因多态性与精神分裂症的相关性.方法 采用等位基因特性PCR方法对272例男性精神分裂症患者和206例对照DAOA基因区域的3个单核苷酸多态性位点(SNP:rs778294,rs778293和rs3918342)进行基因分型和统计分析.结果 DAOA基因区域rs778294的一个等位基因(C)与精神分裂症显著相关(P=0.03).由3个SNP构建的单倍型分析表明,单倍型CAT在病例-对照组中表现出显著的差异.结论 在中国汉族男性群体中,DAOA基因可能是精神分裂症的一个易感基因,NMDA受体途径可能是发生精神分裂症的一个重要潜在因素. 相似文献
36.
With the rudder angles getting larger and larger, the moment and force on propeller shafts, which are caused by complex flowing field, become more and more. They influence the shafting alignment greatly. Stress analysis of propeller shafts has been done under increasing rudder corner conditions with complex hydrodynamics simulation for a great domestic liquified natural gas (LNG) vessel, which is with dual propulsion systems. The improved three-moment equation is adopted in the process of dual propulsive shafting alignment. The calculated results show that the propeller hydrodynamic characteristics, which affect dual propulsive shafting alignment greatly, must be considered under large rudder angle conditions. Shafting accidents of Korean LNG vessels are interpreted reasonably. At the same time, salutary lessons and references are afforded to the marine multi-propulsion shafting alignment in the future. 相似文献
37.
Autonomous underwater gliders are highly efficient, buoyancy-driven, winged autonomous underwater vehicles. Their dynamics
are multivariable nonlinear systems. In addition, the gliders are underactuated and difficult to maneuver, and also dependent
on their operational environment. To confront these problems and to design an effective controller, the inverse system method
was used to decouple the original system into two independent single variable linear subsystems. The stability of the zero
dynamics was analyzed, and an additional closed-loop controller for each linear subsystem was designed by sliding mode control
method to form a type of composite controller. Simulation results demonstrate that the derived nonlinear controller is able
to cope with the aforementioned problems simultaneously and satisfactorily. 相似文献
38.
39.
40.
水下滑翔机动力系统工作性能的研究 总被引:2,自引:1,他引:1
从温差能驱动水下滑翔机的运动轨迹和航行环境出发,对感温工质获取温差能的相变过程进行动态分析,以确定滑翔机工作特性.研究表明,液相感温工质与海水的对流换热效应,导致暖水层航程中的固液相变效率远高于冷水层航程;根据相变的过程特征,动力系统在一个锯齿形航行轨迹中,可分为6个工作过程加以研究;分析感温工质液态和固态的保持时间,可确定滑翔机的航行深度范围,也为动力系统的控制和单向阀的动作时序控制提供了依据,保证了滑翔机动力系统循环工作的特性. 相似文献