钢板与砂泥岩混合填土接触面力学特性试验研究

基于直接剪切试验原理,研究了钢板与砂泥岩混合填土接触界面的剪切力学特性。试验中,钢板采用Q235钢材制作;砂泥岩混合土料采用弱风化砂岩和泥岩的破碎颗粒料按照5种不同的颗粒级配曲线以质量比8∶2配制。试验结果表明,钢板与砂泥岩混合填土接触界面的剪切应力-位移曲线可用双曲线拟合;抗剪强度可用摩尔-库伦强度准则来描述;抗剪参数粘聚力值随土体特性粒径d10,d30,d50,d60,d90的增大呈先减小后增大的抛物线型变化;摩擦角值随土体特性粒径d10,d30,d50,d60,d90的增大呈先增大后减小的抛物线型变化;粘聚力和摩擦角与土体不均匀系数和曲率系数的相关性不明显。     

Solving procurement problems in public transport: Examining multi-principal roles in relation to effective control mechanisms

Despite the EU’s increasing role in regulating public transport procurement, few studies have considered this aspect when analysing procurement problems of public transport. This paper examines how the institutional relationships between different actors, including international governmental bodies, in public transport effects the possibility of exerting control over a county public transport authority (PTA) in a multi-principal setting. The analysis is carried out using empirical material from an infringement process including a Swedish PTA and the EU. The conclusions have clear policy implications for the procedural order when exerting control over the PTA in cases of procurement problems. It is for example shown, that the implementation process would be much more efficient if the regulations allowed the EU to impose sanctions directly towards the local authorities without having to involve the national government when the procurement laws are violated.     

自适应路径规划系统研究

针对目前的路径规划系统普遍采用距离最短或时间最少等单一指标,不能自动识别驾驶员路径选择习惯,为驾驶员自适应地提供符合驾驶员偏好的诱导路径的问题,设计了自适应路径规划系统的框架,提出了一种基于驾驶员路径选择偏好的自适应路径规划算法。算法中设计了基于驾驶员路径选择偏好的多目标路阻函数、基于主成分分析和加权评分分析的评价指标确定方法以及驾驶员路径选择偏好权重的确定方法。最后,利用Mapx、VisualC＋＋和Access数据库联合开发出了自适应路径规划系统,并用长春市驾驶员的实例数据验证了系统的有效性和算法模型的正确性。     

Short-term liner shipping bunker procurement with swap contracts

The bunker price fluctuations in recent years have severely threatened the stability of liner shipping companies’ operations. As an efficient countermeasure, the swap contract is widely adopted throughout the liner shipping industry to hedge the procurement risk resulting from the bunker price fluctuation. This paper looks at the short-term liner shipping bunker procurement problem with swap contracts (BPPSC), aiming to optimally plan the amount of bunker purchased from the spot market and the amount hedged by the swap contract for several months ahead. This BPPSC is first formulated as a bunker procurement cost mean-variance minimization (MVM) model, and is subsequently solved using a tangible two-step approach developed in this study. In the first step, the movements of the swap contract price and the spot market price of the bunker are described using a calibrated multivariate generalized autoregressive conditional heteroskedasticity (mGARCH) time series model. In the second step, the MVM model is approximated and solved by a price scenario tree constructed from the mGARCH time series model. A numerical example shows that the risk hedging strategy obtained can simultaneously control the bunker procurement cost as well as the procurement risk from price fluctuations. This article is a revised and expanded version of the abridged eight-page paper entitled ‘Optimal hedging for liner bunker procurement’ presented at ‘2015 International Conference on Logistics and Maritime Systems (LOGMS 2015)’, Hong Kong, 27–29 August 2015.     

颗粒组成对冰水堆积土路基填料工程特性的影响

在我国大陆西部地区,冰水堆积地貌较为多见,冰水堆积物数量巨大且分布广泛.这些地区工程地质条件较为特殊,冰水堆积物组成和结构均较为复杂,且不同地域或同一地域不同地区冰水堆积土特性差异巨大,给当地工程施工建设带来巨大困难.以蒲都高速TJ-8标路基工程为依托,通过开展颗粒分析试验、界限含水率试验、击实试验等,分析颗粒组成、颗...     

骨架密实型沥青混合料矿料级配的设计与优化

在有关沥青混合料矿料级配设计理论与方法的基础上,提出了在拌制沥青混合料试验之前,先由筛分试验结果和测试的材料密度对骨架密实型沥青混合料进行矿料级配设计的方法,并利用Matlab、Excell等办公软件对矿料组成进行了优化.按该方法设计的矿料级配拌制沥青混合料,进行了动稳定度和冻融劈裂试验.结果表明,在相同原材料条件下,按该方法设计与优化的矿料级配拌制的沥青混合料具有比按规范级配范围中值拌制的沥青混合料具有更好的路用性能,尤其是高温稳定性和表面抗滑性.     

Environmental benefits from improving transportation efficiency in wood procurement systems

Forest operations use fossil fuels, which should be considered when environmental impact in the wood procurement is of concern. Road freight transportation is the most common operation in timber transportation, and thus is an important source of greenhouse gas emissions. This study assesses the impact of the new larger and heavier vehicles (LHV) on environmental emissions using the synchronized calculation method. The maximum (theoretical) and operational effects of 76 t LHV with calculations made for three weight limits (60, 64 and 68 t) are compared in Finland. Based on Enterprise Resource Planning (ERP) data, environmental energy efficiency (measured in relation to the trip) increased 9.2%. The reduction in fuel consumption was 12.5%, though this is likely to under-estimate the long-term effects that will be achieved when forest operations are fully adjusted to the maximum weight limit. A comparison with the European countries and a preliminary sensitivity analysis of the system demonstrate that the technological development to improve the transporting efficiency is essential for realizing 76 t LHV utilization in Finland.     

沥青混合料生产配合比的确定

在沥青混合料目标配合比给定之后,针对间歇式热拌沥青混合料生产设备的工作特点,在振动筛倾斜角和振动筛振动频率等已知条件下,根据现有矿料初次筛分,再经过热料仓取料二次筛分、矿粉含量优化等过程后,准确确定生产配合比。通过进行此配比的沥青混合料的抽提和马歇尔试验,表明各项指标达到设计要求,从根本上保证了沥青混合料的质量及路用性能。     

计及指标重要度的地铁供电设备健康状态分级评估方法

针对现有维修模式中存在的“维修不足”和“维修过度”等问题,提出了一种计及指标重要度的地铁供电设备健康状态分级评估方法。根据层次分析和模糊统计相结合的方法求解设备健康值,并将指标的重要度考虑在内,对设备所处的健康状态进行等级划分,最后以干式变压器为例进行实例分析。研究结果表明：利用本文提出的评估方法能够合理地表征地铁供电设备的健康状态,与实际情况符合,验证了方法的准确性及可行性。     

安山岩集料级配设计

研究了安山岩的路用性能,安山岩内摩阻力大,安山岩表面的孔隙吸收了大量沥青,给安山岩的级配设计和推广使用造成了困难。根据安山岩物理性质的特殊性,提出了针对安山岩的断级配。采用该级配生产的安山岩沥青混合料,具有较好的水稳定性和优异的高温稳定性。在安山岩的推广应用上做了一些探索,以缓解当前某些地区资源紧张的压力,也给其他地区集料和级配的选择增加了可选的范围。