基于三维仿真的自动化集装箱码头堆场布置形态

为探究垂直岸线布置的多泊位自动化集装箱码头工程中集装箱水-水中转集疏运比例对自动化集装箱堆场布置形态的影响,在目前国内典型自动化集装箱码头工艺模式及平面布置的基础上,运用Flexterm对堆场垂直于码头岸线和平行于码头岸线2种布置模式进行三维仿真。通过分析2种布置形态下水平运输设备的运距以及对码头装卸效率的影响,总结2种堆场布置形态对垂直岸线布置的自动化集装箱码头工程的适应性,为类似自动化集装箱码头工程的设计提供理论依据。     

悬挂式单轨空、重车线路动力学响应分析

基于多体动力学软件Universal Mechanism建立60自由度的悬挂式单轨车辆系统动力学模型,主要基于乘客舒适度评价指标,探讨空、重车以80 km/h速度通过平竖曲线时动力学响应的异同。结果表明,结构的特殊性使得悬挂式单轨驶过缓圆点和缓直点后车体横向摆动幅度明显,车体横向偏角时变率、未被平衡离心加速度及其时变率结果均会产生一个较大的跃变现象,且重车工况下变化量更大。由于重车惯性更大的缘故,导致振动衰减过程中车体横向低频晃动更剧烈,同一平面线路工况下,重车比空车要多3个振动衰减周期;竖曲线条件下空、重车的振动衰减周期基本一致,但重车的最大垂向加速度更大。因此,鉴于空、重车在平竖曲线处动力特性差异的事实,有必要综合考虑两者用以后期悬挂式单轨列车线路参数的确定。     

平纵组合路段事故严重程度致因辨识模型

为解析平纵组合路段事故严重程度致因及影响机制，在系统选取影响事故严重程度潜在变量的基础上，利用有序Logit模型获取影响事故严重程度的显著自变量，并运用偏比例优势模型修正变量参数，从而构建平纵组合路段事故严重程度致因辨识的两阶段模型 (TSM)，以云南省元(谋)-双(柏)公路为例进行分析.结果表明：提出的TSM模型比有序概率模型拟合度更优，更适用于研究该问题；涉及车辆数、平曲线曲率及竖曲线曲率等7个变量对一般及以上事故具有正效应，驾驶人性别及接入口等3个变量对一般及以上事故具有负效应；就影响程度来看，接入口最大(边际效应为14.466%)，驾驶人性别次之(10.581%)，竖曲线长度最小(0.114%).     

波纹腹板开孔对预应力钢-混凝土组合梁抗火性能影响研究

桥梁工程中为了方便工程检修与管线布设,经常在梁腹板上开孔。为研究腹板开孔对预应力波纹腹板钢-混凝土组合梁抗火性能的影响,按照完全抗剪连接设计了2片承受两点对称集中荷载作用的预应力波纹腹板钢-混凝土简支组合梁,其中一片是预应力波纹腹板开孔组合梁,另一片是预应力波纹腹板无孔组合梁;采用ISO834国际标准升温曲线对其进行了恒载升温耐火试验,同时采用有限元软件ABAQUS对其进行了数值研究。研究结果表明:高温下2类预应力波纹腹板钢-混凝土组合梁均在剪弯区发生剪切屈曲;在截面尺寸和跨度相同条件下,承受相同的绝对荷载时,腹板开孔后的预应力波纹腹板钢-混凝土组合梁相对于后者在临界状态下抗弯刚度降低,抗火性能下降;在高温作用下,腹板开孔波纹腹板钢-混凝土组合梁相对于腹板未开孔波纹腹板钢-混凝土组合梁,预应力拉索的效率更高,下降速率更慢;腹板开孔后的预应力波纹腹板钢-混凝土组合梁,在升温后期其滑移曲线发展速率略高于腹板未开孔钢-混凝土组合梁;对于腹板开孔波纹腹板钢-混凝土组合梁,在未出现腹板局部屈曲截面上,腹板分担的剪力可达截面总剪力的78%;开孔截面的总剪力几乎完全由混凝土板承担;临界状态下钢梁腹板正应力略高于常温下的腹板正应力水平。     

Centrifuge modelling of a combined pile-type anchor subjected to general inclined loading

One of the main challenges associated with anchoring offshore platforms is the logistic needed to install them in deep water. The growing need for high capacity anchors has prompted the development of new systems where the feasibility of transporting them out to sea is a crucial consideration. With respect to torpedo piles used by Petrobras in Brazil, new platforms installed in deep water required robust anchoring systems, and a cluster of small torpedoes was considered instead of one large torpedo. However, torpedo pile installation is hindered by deep water streams, which can deviate their trajectory during the fall. This is of great concern for the design of torpedo pile clusters because the distance between the piles cannot be controlled during installation. The present study aims to determine the variation in the load capacity of a cluster or array of single piles as a function of the distance between the piles and the load direction after installation on the seabed. To that end, a series of centrifuge tests were carried out on pile clusters installed in loose sand, varying the distance between the piles and the loading direction. The results show considerable interactions between the adjacent piles depending on the load direction and pile spacing. The optimal spacing for maximum cluster efficiency was determined, and comparisons were made with values from the literature for capped pile clusters.     

大型船舶深水抛锚控制关键因素

大型船舶在深水抛锚时容易出现安全问题,如丢锚、弃链、损坏锚机等。研究了船舶深水抛锚时的极限水深、出链长度和抛锚方法等,提出了大型船舶深水抛锚控制的关键因素,可供相关人员参考。     

大型船舶T型材焊接工艺试验及工艺再造

焊接是船体装配中的重要环节,是船体质量好坏的决定性因素。因此,对焊接进行工艺试验是必要的。针对在实际生产过程中,船舶T型材坡口宽度不一致,通常是上宽下窄的情况,选取不同间隙的坡口进行工艺试验,并对获得的参数进行数学建模,推算出具有普遍适用性的焊接参数。     

高速铁路大高差桥墩竖向温度变形对行车舒适性和安全性影响研究

墩顶竖向变形是高速铁路桥梁安全的重要参数之一。在温度效应下,相邻桥墩高差较大时,桥梁会出现竖向变位差,造成轨道不平顺,这将影响高速铁路的舒适性和安全性。目前国内各类规范对桥墩竖向变形的限值规定不尽相同,为了研究大高差桥墩顶竖向变形的温度效应影响,以合福高铁巷坑大桥为例,对大高差桥墩在温度效应下的墩顶竖向变形进行现场测量,将测量和计算结果同各类规范进行对比,进一步对考虑温度效应时车辆通过桥梁结构时耦合响应进行仿真分析,结果表明:巷坑大桥桥墩顶竖向变形差超过规范限值,但车辆通行时的舒适性和安全性均能满足规范要求,车辆走行性偏于安全,合福高铁通车至今该桥一直运营正常。综上所述,现行规范对大跨度桥梁桥墩的变形指标要求偏严,特殊情况下无法满足规范要求时,建议参考公式,适当放松验收指标。本研究对突破规范限制,在大跨度桥梁铺设无砟轨道具有重要的意义。     

An analysis of airport–airline vertical relationships with risk sharing contracts under asymmetric information structures

We analyze the double moral hazard problem at the joint venture type airport–airline vertical relationship, where two parties both contribute efforts to the joint venture but neither of them can see the other’s efforts. With the continuous-time stochastic dynamic programming model, we show that by the de-centralized utility maximizations of two parties under very strict conditions, i.e., optimal efforts’ cost being negligible and their risk averse parameters both asymptotically approaching to zero, the vertical contract could be agreed as the optimal sharing rule, which is the linear function of the final state with the slope being the product of their productivity difference and uncertainty (diffusion rate) level index.If both parties’ productivities are same, or the diffusion rate of the underlying process is unity, optimal linear sharing rule do not depend on the final state. If their conditions not dependent on final state are symmetric as well, then risk sharing disappears completely. In numerical examples, we illustrate the complex impact of uncertainty increase and end-of-period load factor improvement on the optimal sharing rule, and the relatively simple impact on total utility levels.     

Airport capacity choice under airport-airline vertical arrangements

This study investigates the effects of airport-airline vertical arrangements on airport capacity choices under demand uncertainty. A multi-stage game is analysed, in which competing airlines contribute to capacity investments and share airport revenues. Our analytical results suggest that for a profit-maximising airport, such a vertical arrangement leads to higher capacity but may not increase its profit, whereas for a welfare-maximising airport, such an arrangement has no effect on capacity or welfare. Capital cost savings brought by airport-airline cooperation, if any, always lead to higher capacity, and to higher profit for a profit-maximising airport and higher welfare for a welfare-maximising airport. Numerical simulations reveal that win-win outcomes may be achieved for an airport and its airlines without government intervention.