Three-dimensional vortex-induced vibrations of a circular cylinder predicted using a wake oscillator model

This paper reports a numerical study based on a wake oscillator model, to determine the three-dimensional vortex-induced vibration (VIV) responses on a flexible cylinder with pinned-pinned boundary conditions subjected to a uniform flow. Four different aspect ratios have been selected for the study. The coupling equations of the structural oscillator models and wake oscillator models in both the cross-flow (CF) and in-line (IL) directions have been solved using a standard central difference method of the second order. The structural displacement, structural frequency, response wave pattern, response trajectory, and lift force coefficient, for four aspect ratios, have been compared. The numerical results establish that, for a small aspect ratio, the CF displacements have absolute standing wave behaviors without travelling wave behaviors, and the IL displacements have dominant standing wave behaviors with slight travelling wave behaviors. Further, the VIV trajectory is repeatable and displays figure-eight shapes. However, for a large aspect ratio, the CF displacements display identical characteristics with the IL displacements for a small aspect ratio, and the IL displacements for a large aspect ratio are simultaneously dominated by standing and travelling wave behaviors. Moreover, the VIV trajectory is apparently aperiodic and shows chaotic shapes.     

基于容差模型的发动机悬置系统稳健优化设计

应用稳健优化设计理论,考虑设计变量的不确定性对结果的影响,建立稳健优化模型。以发动机悬置系统能量解耦为目标,用Pareto遗传算法对系统的刚度参数进行稳健优化,并将优化结果运用Monte Carlo方法进行分析.结果表明,优化方法可以有效提高悬置系统的稳健性。     

浅析新能源汽车发展现状及发展趋势

以新能源汽车发展现状和发展趋势为主线,详细介绍了当前各类新能源汽车的技术特点,并在此基础上系统地分析了未来新能源汽车的发展前景。最后,在权衡目前的技术状态和未来新技术的可行性后,分析了汽车工业发展的趋势。     

浅谈关于泵站节能的一些措施

该文根据泵站的实际特点,阐述了泵站节能所采取的一些措施,可供同行参考。     

Stability enhancement and fuel economy of the 4-wheel-drive hybrid electric vehicles by optimal tyre force distribution

In this paper, vehicle stability control and fuel economy for a 4-wheel-drive hybrid vehicle are investigated. The integrated controller is designed within three layers. The first layer determines the total yaw moment and total lateral force made by using an optimal controller method to follow the desired dynamic behaviour of a vehicle. The second layer determines optimum tyre force distribution in order to optimise tyre usage and find out how the tyres should share longitudinal and lateral forces to achieve a target vehicle response under the assumption that all four wheels can be independently steered, driven, and braked. In the third layer, the active steering, wheel slip, and electrical motor torque controllers are designed. In the front axle, internal combustion engine (ICE) is coupled to an electric motor (EM). The control strategy has to determine the power distribution between ICE and EM to minimise fuel consumption and allowing the vehicle to be charge sustaining. Finally, simulations performed in MATLAB/SIMULINK environment show that the proposed structure could enhance the vehicle stability and fuel economy in different manoeuvres.     

基于非稳态温度场解析解的沥青混凝土路面温度分布研究

研究以实测气象资料来预估沥青混凝土路面结构层内温度场的分布状况为目的.通过分析太阳辐射、大气温度两种主要影响参数,运用传热学理论建立沥青混凝土路面二维非稳态温度场解析方程.并在云南大理地区埋设温度传感器进行实时数据采集,对计算模型和实测数据相关关系进行了对比分析.最终在云南省不同温度分区基础上,计算得到不同路表温度的结构内部温度分布曲线.研究结果表明:建立的以太阳辐射和大气温度日变化规律为基础的温度场解析方程模型计算结果与实测结果相比,误差最大3℃左右;温度分布曲线反映出在不同路表温度时,结构内部一定深度内温度分布的规律性和温度梯度的改变趋势,能有效地帮助材料设计,计算结果证明了该模型的合理性和有效性.     

趸船风光互补供电系统的开发研究

分析趸船上使用风光互补供电系统的可行性,通过设计开发的原理、环境分析、典型施工安装案例、环境效益等方面的论证,证明风光互补发电系统是具有较高性价比的一种新型能源发电系统,具有很好的应用前景。     

外置式液压蓄能鱼雷发射装置缩比模型假海试验方案仿真分析

为研究及探索外置式液压蓄能鱼雷发射装置关键技术,根据相似准则,按照1:3的比例设计了该装置的缩比模型假海试验方案,并做了仿真分析。仿真结果显示,该方案能较好地反映原型机的内弹道性能。在确定相似准则后,还可以根据具体实际需要,选择不同的比例系数进行缩比模型试验。本文为外置式液压蓄能鱼雷发射装置缩比模型假海试验提供了理论依据。     

ERTG能量回收节能及全电动转过场系统的应用

为了提高使用岸电的场桥(ERTG)的工作效率,研制了ERTG的能量回收系统和全电动转场系统。论述了能量回收节能及全电动转过场系统的原理、工况及操作规程。该系统取消了柴油发电机组,转过场时实现无间断电源及全电动操作,同时该系统能够吸收部分势能,起到节能作用,实现了ERTG全电动作业及真正的零排放。     

系泊船舶在横浪作用下撞击能量计算参数Cm 取值研究

船舶附加水体质量系数Cm的取值对计算系泊船舶在横浪作用下的撞击能量具有十分重要的影响,目前国内外相关文献对该参数取值差异较大,且国内水运行业规范的参数取值偏小,给结构安全带来一定隐患。经过对取值规定的比较,并参照计算公式、结合工程实例分析计算结果,得知国内现行规范Cm的取值明显小于国内外相关规范和研究报告的取值。建议20万吨级以上船舶增大Cm取值为1.7～2.0。