浅谈旋挖钻孔桩坍孔原因及处理措施

论文通过沈阳地区某深基坑支护工程支护桩施工实例,从旋挖钻机成孔工艺原理出发,分析旋挖钻机在砂卵砾石层中坍孔事故的原因,提出施工中应注意问题和控制坍孔事故的措施。在不可避免出现坍孔事故的情况下,通过理论和实践的结合,给出了几种可行的处理措施方案。笔者目的在于为类似的深基坑支护桩施工工程提供可借鉴的经验。     

桩板墙在万州某滑坡体整治工程中的应用

以桩板墙在重庆万州某滑坡体整治工程中的应用为例,介绍滑坡体处治中的处理方案的选择及相关施工。实践表明,对于库区处于陡坡的滑坡体,采用桩板墙是一种有效提高边坡安全系数的滑坡处治措施。     

质子交换膜燃料电池汽车冷起动性能的研究

建立了一个质子交换膜燃料电池电堆的冷起动模型,对燃料电池汽车的冷起动性能进行仿真,旨在通过对电堆中不同位置、不同数量的电池进行外部加热,使电堆充分利用自身的热量,以减小冷起动过程中所需的外部加热功率。结果表明,该方法可使电堆中有更多的单电池在冷起动过程中恢复工作,冷起动的时间更短,从而明显有效地提高燃料电池电堆的冷起动性能。     

动力总成悬置动静刚度的应用与影响因素

对发动机动力总成悬置的动刚度和静刚度参数的确定及相互关系进行阐述,提出动力总成悬置匹配计算中关于动、静刚度的一般选取原则,指出影响动刚度值的因素主要有频率、预载荷和动态载荷幅值三个因素。     

Impact of hilly road information on fuel economy of FCHEV based on parameterization of hilly roads

Under real-life driving conditions, hilly roads are prevalent. Hilly road profile substantially influences fuel economy (FE) due to large impacts (increase or decrease) on power demand profile. Thus, the utilization of future altitude profile information has large potential to improve FE. In this paper, for optimal energy management of fuel cell hybrid electric vehicles (FCHEV), we investigate how much FE could potentially be improved when future altitude profile information is available. In particular, the simulation results are analyzed to justify the reason for this potential improvement and to identify which characteristics of hilly roads leads to large FE improvements. First of all, four statistical parameters are defined to characterize hilly roads: mean value, standard deviation (STD), distance interval (DI), and total distance. Then, several types of virtual hilly roads are generated based on various parameter combinations. In order to evaluate the potential FE improvement two energy management strategies (EMSs) are utilized: the first is Dynamic Programming, which evaluates the globally optimal FE when future hilly road information is available; the other is the Equivalent Consumption Minimization Strategy (ECMS) with adaptive equivalent factor for charge-sustenance, which represents the baseline EMS when future hilly road information is not available. The results show that downhill roads have much larger potential than uphill roads do for FE improvements when the future altitude profile is properly used for EMS. Furthermore, if the battery capacity is not large enough to handle the difference in potential energy, future hilly road information is more important to prevent violations of the maximum state-of-charge bound.     

Road boundary detection and tracking for structured and unstructured roads using a 2D lidar sensor

Road boundaries can give useful information for evaluating safe vehicle paths in intelligent vehicles. Much previous research has studied road boundary detection, using different types of sensors such as vision, radar, and lidar. Lidar sensors, in particular, show advantages for road boundary extraction including high resolution and wide field of view. However, none of the previous studies examined the problem of detecting road boundaries when roads could be either structured or unstructured. In this study, we developed a road boundary detection and tracking algorithm using lidar sensing for both structured and unstructured roads. The algorithm extracts road features as line segments in polar coordinates relative to the lidar sensor. The extracted road features are then tracked with respect to a vehicle’s local coordinates using a nearest neighbor filter. The proposed algorithm accurately detected the road boundaries regardless of the road type.     

焊后退火工艺对S355J2W钢焊接接头力学性能的影响

通过显微硬度试验、室温冲击试验和冲击试样显微断口形貌分析,对空冷和退火两种处理的S355J2W钢焊接接头进行了性能研究．结果表明：适当的退火工艺可以降低焊接接头的硬度,消除其残余应力,使焊接接头的组织分布更加均匀,提高焊接接头各微区的冲击性能．     

An enhanced safe distance car-following model

Gipps＇ model, a well-known safe distance car-following model, has a very strict restriction on the car-following behavior that the following vehicle has to maintain the exact safe distance to the leading vehicle to avoid rear crash. However, this restriction is not consistent with the real traffic condition. Due to that, an enhanced safe distance car-following model is proposed first, and then calibrated and evaluated using the field data. Furthermore, the simulation is conducted to analyze the characteristics of the new model. The results of evaluation and simulation illustrate that the proposed model has higher simulation accuracy than the original Gipps＇ model, and can reproduce the stable flow and shock wave phenomena that are very common in real traffic. Moreover, the simulation results also prove that the enhanced model can better stabilize the traffic flow than Gipps＇ model.     

三峡库区变动回水区趸船系留设施疲劳性能评估

针对三峡库区变动回水区重庆段内某一典型码头工程项目,分别计算得到在4种随机过程条件下,其趸船系留设施中各缆绳、锚链在疲劳寿命期内的日均系缆、系锚应力-历时关系。根据Miner线性累积损伤理论,结合各缆绳、锚链材料的T-N曲线,计算得到各缆绳、锚链的总疲劳损伤,并预测各构件的疲劳寿命年限。本文中所用到的疲劳分析理论及计算过程不仅可以为三峡库区变动回水区趸船系留设施疲劳安全整改提供一定程度上的技术支撑,也可为类似工程项目的疲劳设计与评估提供有价值的参考依据。