斜坡式防波堤堤心石动力特性试验研究

我国现行规范规定防波堤堤心材料为重量10～100 kg之间的块石,但实际工程往往很难达到这一重量范同的标准.如果利用重量范隔更大(如:1-800 kg)的块石作为堤心石,对整个斜坡堤的正常工作影响如何,同前国内对这方面的研究较少.因此,结合深水斜坡堤的丁程实例,利用模型试验,对不同重量范围的堤心石进行动力特性方面的研究.初步结论认为,1～800 kg块石作为堤心石,其动水压强较10～100 kg的值大,而静水压强较小.     

热油泵机械密封泄漏原因及对策

冷却系统结垢后,摩擦副端面温度过高,这是导致热油泵机械密封失败的根本原因.采取软化水夹套冷却和新增静环背冷等措施,可降低摩擦副端面温度,从而解决密封泄漏的问题.     

能效设计指数EEDI功率曲线的直接计算方法

船舶能效规则强制生效后，所有适用船舶必须满足Attained EEDI≤Requied EEDI的条件，因此准确估算或预报功率曲线从而计算得到Attained EEDI将对适用船型具有极为重要的意义。根据国内外关于功率-转速-航速预报的最新进展，依据螺旋桨敞水性能图谱，采用KT/J^2系数，给出了功率曲线的直接计算方法，经实际算例验证，该方法相对传统的间接计算方法更为清晰简便，且结果准确可靠。     

A substitute model of two-dimensional dry friction exposed to dither generated by rolling contact of wheel and rail

Dither generated by rolling contact of wheel and rail smoothes dry friction damping provided by the primary suspension dampers of freight wagons and it should be taken into account in numerical simulations. But numerically the problem is non-smooth and this leads to long execution time during simulation, especially when the vehicle with friction dampers is modelled in the environment of an multi-body system simulation program, whose solver has to cope with many strong non-linearities. The other difficulty is the necessity of handling within the code a number of big volume files of recorded dither sampled with high frequency. To avoid these difficulties, a substitute model of two-dimensional dry friction exposed to dither is proposed that does not need application of dither during simulation, but it behaves as if dither were applied. Due to this property of the model, the excitation of the vehicle model by track irregularities may be supplied as low-frequency input, which allows fast execution and, the necessity of handling high-volume files of recorded dither is avoided. The substitute model is numerically effective. To identify parameters of the substitute model, a pre-processing employing a sample of the realistic dither is carried-out on a simple two-degrees-of-freedom system. The substitute model is anisotropic, describing anisotropic properties of the two-dimensional friction arising in the presence of one-dimensional dither. The model may be applied in other branches of engineering, for example, in mechatronics and robotics, where application of dither may improve the accuracy of positioning devices.     

摩擦焊在十吨挂车车轴焊接中的应用

摩擦焊技术以其可靠的工艺、稳定的质量、安全的使用性在汽车零部件制造中得到认可。摩擦焊过程参数控制和工艺验证，是保证挂车车轴焊接可靠性的重要条件，对挂车车轴生产质量的稳定起着关键性作用。     

Multibody dynamics modelling of the freight train bogie system

Previous work in the railway technology laboratory at Virginia Polytechnic Institute and State University (Virginia Tech) focused on better capturing the dynamics of the friction wedge, modelled using three-dimensional rigid body dynamics with unilateral contact conditions. The current study extends the previous work to a half-bogie model treated as an application of multibody dynamics with unilateral contact to model the friction wedge interactions with the bolster and the sideframe. The half-bogie model was derived using MATLAB and functions as a three dimensional, dynamic, and multibody dynamics model comprised of four rigid bodies: a bolster, two friction wedges, and a sideframe assembly. This expanded model allows each wedge four degrees of freedom: vertical displacement, longitudinal displacement (between the bolster and sideframe), pitch (rotation around the lateral axis), and yaw (rotation around the vertical axis). The bolster and the sideframe are constrained to have only the vertical degree of freedom. The geometry of these bodies can be adjusted for various simulation scenarios. The bolster can be initialised with a pre-defined yaw (rotation around the vertical axis) and the sideframe may be initialised with a pre-defined pitch/toe (rotation around the lateral axis). The results of the multibody dynamics in half-bogie model simulation are shown in comparison with results from NUCARS^®, an industry standard in train-modelling software, for similar inputs.     

如何提高路基分层压实系数一次验收合格率

通过包西铁路通道陕西段路基土方填筑施工过程的实践,分析总结影响路基分层压实系数一次验收合格率的多种因素,有针对性地制定相应工程措施,指导施工生产。     

车市波动规律的新发展

为分析中国车市当前发展趋势，给汽车产销单位和领导机关决策提供参考，文章采用“车市波动分析法”，从宏观经济与车市波动关系入手，进行数据处理，作出车市波动图和数据表。分析研究后得出以下结论：中国车市2009年底已进入“第6次扩张高峰期”，达到创纪录的新水平，但后继波动恐难避免。文章根据中国车市发展实际提出波形组成内容变化新建议。     

30年来中国轿车市场的5次波动

系统论述了中国轿车市场1978--2008年发生的5次波动。通过对前4次波动的研究，提出了新的车市研究方法体系一车市波动分析法，该方法成功预报了第5次波动期的主要阶段。详细介绍了轿车市场第5次波动期的全过程，分析了中国轿车市场波动规律的“井喷”和“余喷”现象，以及2009--2010年轿车市场发展趋势。     

汽车载质量利用系数公告申报管理合理上限研究

目前汽车企业申报"小吨大标"车越来越多,严重地影响到车辆的行驶安全。本文通过三辆车的试验结果分析载质量利用系数的合理上限值,以限制"小吨大标"车的申报,为相关管理部门提供参考。