整平机升降系统设计与分析

本文依托一种自浮式水下基床整平机,对该整平机上的重要的组成部分——升降系统进行了设计与分析,提出了一种结构简单、运行可靠的升降系统；对组成升降系统的升降机构提出了液压环梁插销式升降机构、齿轮齿条式升降机构和液压缸升降机构,对支撑机构考虑了十字转动支撑机构和万向球轴承支撑机构,对锁紧机构提出了楔块锁紧机构和棘爪锁紧机构,通过对各种方案进行分析论证,最终确定了升降系统由液压缸升降机构、十字转动支撑机构和棘爪锁紧机构组成；最后对棘爪锁紧机构进行了瞬态动力学计算,计算结果得出棘爪锁紧机构所受最大应力为154.52MPa小于其许用应力172.5MPa,验证了棘爪锁紧机构的强度满足要求。     

F型与直壁型护栏在客车撞击下的仿真研究

为了对比研究A类防撞等级中F型混凝土护栏和直壁型混凝土护栏的防护性能,建立两种护栏与客车的有限元模型,运用ANSYS Workbench软件中显式动力学模块,控制仿真碰撞的试验参数,将大客车模型以规定的初速度和碰撞角度进行计算机仿真碰撞试验,从车辆的加速度、车辆运行轨迹、护栏的最大动态变形量等方面综合对比两种护栏的防护性能。结果表明:相比直壁式护栏,F型混凝土护栏防撞性能、安全性能、导向性能较好。     

基于AR模型的并靠两船相对运动预报研究

根据两船相对运动的特点,利用两船模相对运动的测量数据,运用基于自回归模型的时间序列分析法,建立了两船相对运动的数学模型,并给出了运动姿态的预报值.通过本方法的研究,可以得到满意的相对运动预报精度,为两船补给波浪、补偿装置的开发打下了理论基础.     

软弱富水地层浅埋暗挖隧道地表沉降和支护结构受力的模型试验

以莞惠城际轨道交通工程项目GZH-5标段中DK32+300~DK32+927.303段为背景,通过2组模型试验,其中一组无超前注浆,另一组进行超前注浆,研究软弱富水地层浅埋暗挖隧道地表沉降和支护结构受力规律及超前注浆对其受力变形造成的影响,最后,针对软弱富水地层浅埋暗挖隧道施工,提出几点隧道工程设计和施工的相关建议。     

基于基准有限元模型的箱梁TMD振动控制研究

针对高架桥梁结构引起的振动噪声问题,研究TMD控制箱梁结构振动的特性。为了获得精准的箱梁有限元模型,首先以铁路32 m简支箱梁桥为原型,按10:1的几何相似比设计制作简支箱梁缩尺试验模型,应用ANSYS软件建立初始动力有限元模型;对有限元模型模态分析与试验模型模态测试得到的自由模态信息进行误差分析,并采用基于灵敏度分析的模型修正技术对初始动力有限元模型弹性模量和密度进行修正,得到基准有限元模型,误差确认结果显示修正后的有限元模型更精准地反应箱梁的振动特性;进一步利用基准有限元模型,开展TMD控制简支箱梁桥振动的研究,研究结果表明TMD对于抑制桥梁竖向共振有很好的效果。     

铁路路基动态变形模量的数值模拟分析

介绍铁路路基动态变形模量理论计算公式的推导及动态变形模量的测试原理,采用有限元软件模拟动态变形模量的测试过程,分析承载板与土体接触压力、路基动态变形模量的影响因素,并计算动态变形模量的有效测试深度.结果表明:在承载板中心一定范围内,接触压力模拟结果较理论计算值大;土体的动弹性模量对接触压力影响很小,可以忽略;路基动态变形模量测试冲击荷载作用下,土体只发生弹性变形;动态变形模量与土体动弹性模量呈线性关系,路基动态变形模量的模拟结果大于理论计算值;土体的泊松比对动态变形模量影响较小;动态变形模量有效测试深度建议取0.5~0.6 m.     

跃龙门隧道多功能钢拱架安装机快速施工配套技术

隧道施工机械化是我国隧道施工的发展方向。相较于开挖、衬砌机械化的快速发展,钢拱架安装机械化水平存在不足,长期以来较多采用人工作业,施工人员多、劳动强度大、施工效率及安装精度低,同时存在很大的安全隐患。本文通过跃龙门隧道机械化配置配套应用,分析了钢拱架安装机在机械化快速施工体系中的关键作用,并详细介绍了XZGMT411多功能钢拱架安装机相关参数、施工操作要点及注意事项。多功能钢拱架安装机的使用大幅提高了隧道施工效率及施工质量,缩短了施工工期。     

Eco-driving behaviors of electric vehicle users: A survey study

Previous research has shown that electric vehicle (EV) users could behave differently compared to internal combustion engine vehicle (ICEV) drivers due to their consciousness or practices of eco-driving, but very limited research has fully investigated this assumption. This research explores this topic through investigating EV drivers’ eco-driving behaviors and motivations. We first conducted a questionnaire survey on EV drivers’ driving behavior and some hypothetical decisions of their driving. It indicates various characteristics between EV and ICEV commuters, including self-reported daily driving habits, preferences of route choices, tradeoff between travel time and energy saving, and adoption of in-vehicle display (IVD) technologies. Then, through statistical analysis with Fisher’s exact test and Mann-Whitney U test, this research reveals that, compared to ICEV drivers, EV drivers possess significantly calmer driving maneuvers and more fuel-efficient driving habits such as trip chaining. The survey data also show that EV drivers are much more willing to save energy in compensation of travel time. Furthermore, the survey data indicate that EV drivers are more willing to adopt eco-friendly IVD technologies. All these findings are expected to improve the understanding of some unique behavior found in EV drivers.     

Buckle propagation of damaged SHCC sandwich pipes: Experimental tests and numerical simulation

Sandwich pipe (SP) combining high-strength performance and thermal insulation has been considered an effective solution for oil and gas transportation in ultra-deepwater. Strain hardening cementitious composite (SHCC) is well known for its capacity to withstand both tensile load and external hydrostatic pressure. The sandwich pipe considered in the research is constituted of concentric steel pipes with SHCC annular layer. In the present research work, the SHCC was manufactured, and full scale sandwich pipes were assembled. Intact and damaged specimens were submitted to controlled external pressure in a hyperbaric chamber to obtain the collapse and propagation pressures, respectively. Modeling and simulation of the buckle propagation of the SPs were correlated with the experimental results. The results show that sandwich pipe with SHCC core has an excellent structural strength under high external pressure in both intact and damaged conditions. Moreover, the results also show that the interaction between the annular and the inner/outer pipes provides a significant contribution to the buckling resistance under propagation pressure.     

Optimal bus fleet management strategy for emissions reduction

Transportation is a major cause for environmental degradation via exhaust emissions. For many transit-oriented metropolitan areas, bus trips often constitute a sizeable mode share. Managing the bus fleet, in particular updating buses to comply with the newer emissions standards, therefore, can have a substantial impact on transportation-induced air quality. This paper presents the approach of remaining life additional benefit–cost (RLABC) analysis for maximising the total net benefit by either early-retiring or retrofitting the current bus fleet within their lifespans. By referring to the net benefits for different bus types estimated by RLABC analysis, the most beneficial management scheme for the current bus fleet can be identified. Optimal bus fleet management (BFM) models based on the RLABC analysis for the operator and the government are developed. Then a government subsidy plan is produced to achieve win–win solutions, which will offer efficient and flexible management schemes. To illustrate the approach, the largest bus company in Hong Kong, which carries more than 23% of the total trips in Hong Kong, is taken as a case study example. Instead of adopting a fixed retirement plan, such as replacing buses at the age of 17 as is currently practised, the proposed method develops an optimal BFM scheme that progressively phases out buses or retrofits them. This study produces promising results to demonstrate the large benefit of this approach for optimal bus fleet management.