发动机冷却液的作用及添加剂对环境的影响

随着汽车工业科技的不断进步和社会对环境保护意识的不断增强,研发、推广环保型的防冻液成为汽车工业未来的发展方向。     

船用液动阀误动作分析与解决方案

在分析船用液动阀误动作产生原因的基础上,系统加装液单向阀．该单向阀由接头式阀体、锥形阀芯、弹簧等组成,具有结构简单、安装方便的特点,用于现用液压系统的改造,能有效防止液压设备压力波动相互干扰、液压冲击.     

地震-波浪耦合作用下考虑相位差影响的深水桥墩动力响应分析

跨海深水桥墩往往受到不可忽视的波浪作用,在设计时需考虑波浪力.在地震作用下,桥墩附近海域的波浪场受到地震动水压力的干扰,波浪作用也受到影响,桥墩的动力响应需考虑两者的耦合作用.另一方面,地震起振时,墩底处地震波的相位可简单视为0,而桥墩处的波浪相位可能在0～2π之间变化,地震与波浪之间的相位差将直接影响波浪作用的大小,...     

列车通过3JG和1LQ区段时编码电路的设计与硏究

以某双线自动闭塞铁路区间轨道电路设计为例,针对列车正向通过3JG区段和反向通过1L Q区段时出现闪U2的现象进行分析,对编码电路设计时需要注意的事项进行研究,并提出合理可行的设计建议和改进措施,以期对其他类似工程起到参考和借鉴作用。     

Effect of surface roughness and initial gap on the vortex-induced vibrations of a freely vibrating cylinder in the vicinity of a plane wall

We studied the effects of the surface roughness and initial gap on the responses of vortex-induced vibration (VIV) of a circular cylinder near a stationary plane wall, employing numerical methods. The VIV response amplitudes, lock-in regions, hydrodynamic forces, VIV trajectories and flow fields for three different surface roughnesses and two different initial gaps were systematically compared. The results reveal that the reduced velocity range can be divided into three regions based on the VIV amplitude as pre-lock-in, lock-in, and post-lock-in regions. The width of the lock-in region is not sensitive to the variation of the roughness. The mean drag coefficient has a decreasing tendency with the increased roughness. For a small initial gap, the clockwise wall boundary layer vortices has coalesced with the clockwise vortices shed from the upper side of the cylinder, which further suppresses the shedding of the counter-clock wise vortices from the lower side of the cylinder. The vortex shedding flow pattern displays a weak 2S mode. However, for a large initial gap, there is no coalescing action operating in the wake region and hence most of the vortex shedding flow patterns show an asymmetric 2S mode.     

河床墩台局部冲刷计算公式及其影响因素研究

在介绍国内外桥墩局部冲刷公式的基础上,以泰州长江公路大桥为例,验算了我国现行规范中的桥墩局部冲刷计算公式,分析局部冲刷的影响因素。结果表明:桥墩非黏性土冲刷公式中,65-1修正式计算结果较为合理;影响桥墩局部冲刷深度的因素有潮流作用和偏角大小。     

浅析隆鑫二代三轮自卸摩托车的开发设计

采用液压动力单元的三轮自卸摩托车与传统三轮自卸摩托车相比,发动机动力传递系统与自卸驱动系统相互独立,并且自卸驱动系统集成于一体,使整个结构进一步紧凑,避免了互相产生的不利影响,自卸过程较稳定,拆卸和安装方便,能够安装于不同车辆,通用性较强。     

波浪作用下考虑桩土相互作用的桩柱响应*

以一离岸深水桩柱为例,依据JTJ 2132—1998《海港水文规范》的环境条件和环境荷载规范,对桩柱进行有限元离散。在海洋深水环境条件下考虑流固耦合效应,计算了在海洋极端规则波以及不规则波条件下桩柱的运动响应;为了进一步研究分析泥面以下土体对桩柱运动响应的影响,对比分析了在考虑桩土耦合相互作用下桩柱的响应与基岩面固结解下的响应;考虑到海洋地基为两相饱和土介质,对比了在不同简化阻抗处理下的运动响应结果。结果表明,桩土耦合相互作用对于波浪尤其是不规则波作用下的桩柱响应有很大影响,简化阻抗下的运动响应相比两相饱和地基阻抗处理论误差在10%左右,考虑桩土耦合效应对于工程设计具有指导意义和实用价值。     

小直径钢管排桩支挡结构抗滑机理及工程应用

通过对小直径钢管排桩作为抗滑支挡结构的系统研究,提出其抗滑机理主要表现为桩土复合结构“类抗滑桩”作用,破坏模式为受拉构件锚固段拔出、受压构件桩体弯剪破坏和压杆失稳等。在此基础上,给出了此类支挡结构设计技术要点,包括钢管桩排数确定、桩间距和排间距选择、锚固深度计算、连系梁设计等。小直径钢管排桩在广巴高速公路K78+230~+400段路堤滑坡得到成功应用,确保了高速公路安全,取得了良好的社会、经济效益。     

Improvement actions for reducing transport’s impact on climate: A shipper’s perspective

The purpose of this paper is to compare improvement actions for reducing transport’s impact on climate from the shipper’s perspective. To that end, it introduces an evaluation tool for comparing improvement actions in transport systems in terms of transport costs, impact on climate, and barriers to implementation. Within the context of five international flows involving a food producer, three actions—namely, engaging intermodal transport, increasing load factors by double-stacking pallets, and using high-capacity vehicles—were evaluated. Shipment data were collected to calculate reductions in transport costs and impact on climate, whereas interviews with the food producer were conducted to identify barriers. Results showed that reductions in transport costs and impact on climate attributed to the improvement actions differed among the five flows. Engaging intermodal transport reduced the system’s impact on climate by 27–53%, double-stacking pallets by 0–23%, and using high-capacity vehicles by 7–15%, with differences primarily due to different freight densities. Concerning barriers to implementation, the improvement actions also varied by flow. Altogether, unlike other papers, which have examined improvement actions separately, this paper offers an evaluation tool for comparing several improvement actions at once, as applied to a particular empirical case. Shippers with multiple flows and several possible improvement actions can use the evaluation tool to efficiently reduce their systems’ impact on climate.