排序方式: 共有101条查询结果,搜索用时 843 毫秒
81.
本文首先根据该多用途重吊船设计特点及700t吊车吊重试验和2台重吊联吊作业要求,论述了700t重吊的保障需求,并提出了重吊保障装置的优化配置及随船布置的必要性;然后根据各保障装置的特点提出了平衡浮箱(兼吊重试验标准吊重)、“L”型连接吊臂和联吊梁等保障装置的布置原则;依托全船总布置方案基于该布置原则分别提出了各重吊保障装置各种可能的布置方案,并分析研究各布置方案在总布置、船体稳性、装载能力、吊车使用成本、结构强度、吊用方便程度等多个方面的优缺点,最终确定平衡浮箱布置于1号货舱底部、“L”型连接吊臂立式布置于2号货船右舷通道和边舱围阱内、四根联吊梁沿船宽方向布置于2号货舱与上建之间;并提出了各重吊保障装置详细的布置方案及各保障装置系固设计要求;研究成果可用于支撑多用途重吊船的重吊保障装置设计及布置方案设计。 相似文献
82.
设备在不同运行状态下的最佳保修期分析 总被引:1,自引:0,他引:1
池洁 《重庆交通大学学报(自然科学版)》2008,27(5):831-834
通过对设备故障规律、维修方式的分析,以提高设备利用效率为目标,分析了设备在不同的使用阶段,应采取的维修管理对策。并得出:当故障率λ′(t)=0时(设备偶发故障期),对设备进行预防性维修,不可能提高设备的利用效率;当故障率λ′(t)≠0时(耗损故障期、初期故障期),最佳维修周期T应满足的条件(integral from n=0 to T (tλ′(t)dt)=tp/tf)。同时根据空压机(ZW-17/29)在使用过程中的故障数据,得到了该设备在耗损故障期内的最佳维修周期T,提出设备的维修保养计划。 相似文献
83.
84.
85.
86.
87.
88.
Protection distance of surge protective devices (SPDs) is an important problem in designing a good location scheme of SPDs in low voltage distribution systems for protecting electrical equipments against overvoltage caused by lightning stroke. The simplified lumped-parameter circuit model and the circuit method were used to study the protection distance problem of SPDs. The analytical solutions of the load voltage and generale quations of the protection distance of SPDs under different load conditions were given. Simulation results of examples proved the validity of the proposed analytical method. 相似文献
89.
Bjrn Bohling 《Journal of Marine Systems》2009,75(3-4):330-335
For studies on sediment transport processes experimental data on the erosion behaviour of sediments are necessary. Because of significant differences in experimental setups and subsequently in resulting values comparisons and, where possible, correlations between methods are required. This study presents measurements with two different erosion devices (straight flume and microcosm erosion chamber), which were used for the determination of critical shear stress velocities for sandy submarine sediments and sieved sediment fractions. An approach is presented to convert measured current velocities into shear stress velocities via roughness length values and drag coefficients under hydrodynamically smooth and transitional turbulent flow conditions. The results from both devices show a good agreement and the measured erosion threshold values fit to established correlations between critical shear stress velocity and grain size. In the grain size range below 200 µm results for naturally composed sediments are influenced by effects caused by the silt- and clay fraction. Sieved sediment fractions in this grain size range tend to show lowered erosion thresholds in relation to the Shields' curve. 相似文献
90.