对遇局面中避让行动有效性的评价

根据《1972年国际海上避碰规则》第8条的规定,通过对对遇局面形成判断的详细分析,讨论该局面避让行动的要求,并对避让行动的有效性进行评价。     

白车身随行夹具气路控制的设计

为满足多车型的定位夹紧功能,将零件定位夹具设计成随行夹具,并按新设计的气路控制系统进行顺序动作,随行夹具上气路控制系统进为纯气路控制形式。根据零件定位工艺要求,结合夹具数模设计一种气路控制系统,并根据气缸动作顺序,得出气控系统原理图。纯气路控制系统有以下优点:1、纯气路控制相对安全可靠;2、控制原理简单易懂、层次分明,能保证定位夹具各机构的动作顺序正确,定位精度达到工艺要求。该气路控制系统的设计为汽车白车身随行夹具正常工作提供保证。     

静风效应和架设方法对悬索桥施工过程颤振稳定性的影响研究

悬索桥在施工过程的结构刚度比较小,空气静力作用产生的非线性效应以及桥面主梁架设方法都将对悬索桥施工过程的颤振稳定性产生重要的影响。运用大跨度桥梁颤振分析的三维非线性方法,分析宜昌长江大桥采用不同主梁架设方法时的颤振稳定性变化趋势,并探讨静风效应和主梁架设方法对悬索桥施工过程颤振稳定性影响的程度、机理和规律。     

Joint earthquake and wave action on the monopile wind turbine foundation: An experimental study

Offshore wind turbines in regions of active seismicity are under a potential threat caused by the joint earthquake and ocean wave action. Taking NREL-5MW monopile wind turbine as the prototype, this study is devoted to probe the joint action of strong earthquakes and moderate sea conditions. A series of shake table model tests of scale 30:1 have been carried out by the contemporary world unique facility (Earthquake, Wave and Current Joint Simulation System) to investigate the structural response in dry flume, low and high calm water levels, with and without regular or random waves. Particular interest has been in the nacelle acceleration subjected to strong ground motions as well as to random waves. The experimental results of nacelle peak accelerations and corresponding dynamic amplification factors show that the joint earthquake and wave action is important for the proper evaluation of structural response. Ignoring the effect of wave action in seismic analysis will lead to underestimation of structural response, especially when the monopile foundation is dynamically sensitive. The coupling of earthquake and wave actions is sourced not only from the relative velocity of vibration but also from the initial condition induced by waves. It has been also derived that the peak acceleration excited by a moderate sea condition is comparable to that by a moderate earthquake.     

细胞内记录动作电位测定蛙单根有髓神经纤维强度—时间关系

本文介绍了一种简单的细胞内记录蛙有髓神经纤维动作电位方法。将该方法用于测定神经纤维阈刺激的强度-时间关系,所得结果能够满足一般科研及教学工作的需要。     

混凝土联锁块护底软体排抗掀稳定分析

针对规范中软体排抗掀稳定计算公式未考虑水深影响的问题,对水流作用下混凝土联锁块软体排受力进行研究。采用理论推导方法,得出了新的混凝土联锁块软体排抗掀稳定计算公式,结合数模分析确定新公式的相关参数取值。新公式中考虑了水深的影响,采用临界断面平均流速替代规范公式的软体排边缘临界流速,较规范公式更为准确。分别采用新公式和规范公式对黑沙洲水道航道整治二期工程护底软体排抗掀稳定进行计算。分析结果表明:新公式较规范公式更能反映软体排实际受力情况。工程实践证明新公式具有较好的可靠性,可供类似工程参考和借鉴。     

The effect of wheel set gyroscopic action on the hunting stability of high-speed trains

This study explores the effects of wheel set gyroscopic action on hunting stability by calculating linear and nonlinear critical speeds. First, a dynamic model for a high-speed vehicle with 23 degrees of freedom is developed by considering wheel set gyroscopic action. The linear and nonlinear critical speeds are calculated by eigenvalue analysis and drawing a bifurcation map, respectively. Two computer programs for linear and nonlinear stability analysis are developed. Second, based on an actual high-speed vehicle in China, the effects of wheel set gyroscopic action on hunting stability are quantitatively investigated using computer simulation. Furthermore, the difference between the effects of gyroscopic moments about the x-axis and z-axis is discussed. The results show that the moment about the x-axis is harmful to hunting stability, but the moment about the z-axis is beneficial to hunting stability. However, the integrated effect of these two moments can enhance the critical speeds and suppress the hunting motion.     

无缝线路纵向温度力作用下的动力特性分析

通过建立无缝线路有限元动力计算模型,运用数值分析方法深入分析了无缝线路钢轨的自振频率与温度变化引起的纵向应力之间的关系,为无缝线路钢轨纵向温度力的测试提供一种可行的思路和方法.模型不仅包括钢轨模型、轨下弹性垫板及扣件模型、轨枕模型,还考虑了道床模型及路基模型,并分析了钢轨磨耗以及轨下基础刚度等因素对钢轨竖向振动特性与纵...     

铁路简支T梁混凝土冬季施工

简述了铁路简支T梁冬季施工过程中的混凝土施工,从原材料、搅拌、灌筑、养护到脱模的过程描述,以及冬季混凝土施工中出现的一些质量通病及其防治措施等。实践证明,冬季生产的桥梁混凝土无一处受到冻害,且桥梁结构物表面无裂纹,效果良好。     

议船舶航行中的追越对遇交叉相遇及其避让行动

追越、对遇和交叉相遇是航行中两船相遇的 3种局面 .船舶在航行中如何避免碰撞 ,要正确地判断当时的局面与存在的碰撞危险 ,按《内规》的要求 ,采取有效地避让行动