State observer-based sliding mode control for semi-active hydro-pneumatic suspension

This paper proposes an improved virtual reference model for semi-active suspension to coordinate the vehicle ride comfort and handling stability. The reference model combines the virtues of sky-hook with ground-hook control logic, and the hybrid coefficient is tuned according to the longitudinal and lateral acceleration so as to improve the vehicle stability especially in high-speed condition. Suspension state observer based on unscented Kalman filter is designed. A sliding mode controller (SMC) is developed to track the states of the reference model. The stability of the SMC strategy is proven by means of Lyapunov function taking into account the nonlinear damper characteristics and sprung mass variation of the vehicle. Finally, the performance of the controller is demonstrated under three typical working conditions: the random road excitation, speed bump road and sharp acceleration and braking. The simulation results indicated that, compared with the traditional passive suspension, the proposed control algorithm can offer a better coordination between vehicle ride comfort and handling stability. This approach provides a viable alternative to costlier active suspension control systems for commercial vehicles.     

主汽门安装方式对汽轮机受力影响分析

船用凝汽式汽轮发电机组主汽门通常安装于汽轮机上,工作状态下管道产生的蒸汽力对汽轮机的受力状态有较大的影响。给出三种不同主汽门安装位置与进汽方向的安装方式,通过有限元方法对其受力进行了计算。结果表明,采用主汽门侧挂安装方式会对汽轮机各支点支反力以及各定位键产生较大的不平衡力,恶化汽轮机的稳定性;而采用主汽门中心线安装方式会大大减小各支点受力的不均匀性,同时降低各定位键的侧向力,提高汽轮机的稳定性。     

建设武汉城市圈城际轨道交通的必要性研究

借鉴国内外城市圈城际轨道交通发展经验,分析武汉城市圈社会经济及交通现状与发展目标,从促进区域经济发展、引导城市空间布局、建设“资源节约型、环境友好型”社会、优化综合运输体系、适应城际客流需求等方面论述建设城际轨道交通的必要性。     

低速自润滑滑动轴承油盘带油的试验研究

低速自润滑滑动轴承可靠运行的关键技术,是在低速区能保证提供充足的润滑油,本文就是对一种特殊结构的油盘和集油器进行试验研究,摸索出油盘带油量与各相关物理量的关系,由此来指导设计.     

基于谱分析的船舶模拟器的输入轨迹生成方案

应用Stewart机构模拟船舶在波浪中的不规则摇荡,首要任务是获得机构六通道的输入轨迹。针对这一问题,以模拟船舶的不规则横摇运动为例,将船舶运动谱分析方法与并联机构反解理论相结合,提出了一种输入轨迹的生成方案。将生成的输入轨迹输入到船舶模拟器实验平台中进行实验,实验结果表明所得输入轨迹可以实现Stewart机构对船舶不规则运动的模拟,验证了该方案的可行性,并为模拟船舶不规则摇荡的后续工作奠定了基础。     

基于滑移网格的带桨水面船自航性能预报研究

应用FINE/Marine软件对KCS船、KP505桨以及考虑自由液面的船桨组合体进行数值计算,并计算其自航性能。利用滑移网格技术和随体网格来实现船桨之间的相互耦合。考虑到原有的自航性能数据处理方法并不代表实际情况,文中借鉴强制自航法的概念提出了一种新的船舶自航点求解方法预报船舶自航性能,并与模型试验结果进行比较,吻合良好,其中推力减额系数、伴流分数以及船舶推进效率的计算误差分别为0.5%、2.18%、6.76%。本文研究为预报船舶自航性能提供了一种新的研究手段。     

Estimation of train dwell time at short stops based on track occupation event data: A study at a Dutch railway station

Train dwell time is one of the most unpredictable components of railway operations, mainly because of the varying volumes of alighting and boarding passengers. However, for reliable estimations of train running times and route conflicts on main lines, it is necessary to obtain accurate estimations of dwell times at the intermediate stops on the main line, the so‐called short stops. This is a great challenge for a more reliable, efficient and robust train operation. Previous research has shown that the dwell time is highly dependent on the number of boarding and alighting passengers. However, these numbers are usually not available in real time. This paper discusses the possibility of a dwell time estimation model at short stops without passenger demand information by means of a statistical analysis of track occupation data from the Netherlands. The analysis showed that the dwell times are best estimated for peak and off‐peak hours separately. The peak‐hour dwell times are estimated using a linear regression model of train length, dwell times at previous stops and dwell times of the preceding trains. The off‐peak‐hour dwell times are estimated using a non‐parametric regression model, in particular, the k‐nearest neighbor model. There are two major advantages of the proposed estimation models. First, the models do not need passenger flow data, which is usually impossible to obtain in real time in practice. Second, detailed parameters of rolling stock configuration and platform layout are not required, which makes the model more generic and eases implementation. A case study at Dutch railway stations shows that the estimation accuracy is 85.8%–88.5% during peak hours and 80.1% during off‐peak hours, which is relatively high. We conclude that the estimation of dwell times at short stop stations without passenger data is possible. Copyright © 2016 John Wiley & Sons, Ltd.     

燃油泵滑动轴承摩擦副材料试验研究

船舶燃油泵滑动轴承在贫油及介质中含有大量杂质的状态下易出现故障,利用磨损试验,通过改变轴瓦材料和轴颈表面处理工艺,分析轴承对异物的包容性、嵌藏性和自润滑性能.结果表明,合适轴瓦材料和轴颈表面处理工艺,可降低轴瓦的磨损,提高燃油泵滑动轴承工作的可靠性.     

简支梁桥上连续结合式无碴轨道层间连接设计

针对32m简支梁桥上连续结合式无碴轨道结构,分别用换算截面法、有限元法及刚性简化计算法计算了列车活载、轨道板与底座板间温差及列车制动作用下的层间剪力,得到了层间剪力分布图,依据该图进行了层间连接件的设计。研究结果表明:在列车荷载作用下,层间剪力自梁端至跨中大致呈线性递减分布;轨道板与底座板间存在10℃温差时,层间剪力主要集中在桥梁两端5m范围内;制动力作用下,结合面上层间剪力沿跨长均匀分布,均等于作用在轨道板之上的扣件纵向分布阻力;当三者共同作用时,轨道板与底座板之间的温差起控制作用,因此,桥梁端部受温差影响较大的5m范围内应加密销钉与连接钢筋设置。     

双孔预应力非对称无砟轨道板设计与分析

针对我国高速铁路桥上采用的板式无砟轨道普遍存在线间排水困难和板底易出现横向裂缝问题,提出一种新型双孔型板式无砟轨道,采用有限元软件ANSYS建立三维空间模型,分析在2种不同工况下新型轨道板的应力、变形和承载力性能,并在组合外力矩作用下进行预应力非对称配筋设计.研究结果表明,新型双孔型板式无砟轨道可以有效解决线间排水困难问题,与普通无砟板式轨道相比,新型轨道板具有更好的稳定性;在竖向荷载作用下,双孔型轨道板的最大应力、位移和裂缝宽度均满足设计要求;在配筋总量相对较少的情况下,轨道板的非对称预应力筋设计可以有效减小板底裂缝最大宽度,板底抗裂程度相对于普通轨道板增大33.3%,增强了轨道板的耐久性,且经济性能良好.