Imperfect reversibility of air transport demand: Effects of air fare,fuel prices and price transmission

There are recent evidence that air transport demand may not have a perfectly reversible relationship with income and jet fuel prices, as is assumed in most demand models. However, it is not known if the imperfectly reversible effects of jet fuel price are a result of asymmetries in the supply side, i.e., asymmetries in cost pass through from fuel prices to air fare, or of demand side behavioral asymmetries whereby people value gains and losses differently. This paper uses US time series data and decomposes air fare and fuel price into three component series to develop an econometric model of air transport demand that is capable of capturing the potential imperfectly reversible relationships and test for the presence or absence of reversibility. We find that air transport demand shows asymmetry with respect to air fare, indicating potential imperfect reversibility in consumer behavior. We also find evidence of asymmetry and hysteresis in cost pass-through from jet fuel prices to air fare, showing rapid increases in airfare when fuel prices increases but a slower response in the opposite direction.     

Walking-distance introduced queueing model for pedestrian queueing system: Theoretical analysis and experimental verification

We have introduced the effect of delay in walking from the head of a queue to the service windows in the queueing model and obtain a suitable type of queueing system under various conditions by both computational simulation and theoretical analysis. When there are multiple service windows, the queueing theory indicates that mean waiting time in a fork-type queueing system (Fork), which collects pedestrians into a single queue, is smaller than that in a parallel-type queueing system (Parallel), i.e., queues for each service window. However, in our walking-distance introduced queueing model, we have examined that mean waiting time in Parallel becomes smaller when both the arrival probability of pedestrians and the effect of walking distance are large. Moreover, enhanced Forks, which shorten waiting time by reducing the effect of walking distance, are considered, and parts of our results are also verified by real queueing experiments.     

Incentive Contracts for Venture Capital Syndication

IntroductionThe uncertainty in venture capital market and in-formation asymmetry during venture capital investingprocess make syndication in the second and later sta-ges a hot issue.The syndication is important for re-ducing the risk effectively,increasin…     

不对称连续刚构合拢段的施工控制

结合不对称连续刚构合拢段施工实践,介绍了不对称连续刚构合拢段各施工阶段的控制方法。详细阐述了防止张拉预应力导致箱梁底板混凝土开裂的措施、顶推过程以及合拢段预应力张拉顺序控制等具体内容,并介绍施工控制中需要注意的问题。     

不对称连续刚构桥地震反应分析

文章以贵州省六盘山市一座不对称连续刚构桥为工程实例,利用结构分析软件MIDASCIVIL建立了该桥的有限元分析模型,并选用Taft波与时程分析法计算了该桥的地震响应情况。结果表明桥墩是地震作用下全桥受力最不利的位置,必须重视桥墩的抗震设计和验算。     

20000TEU集装箱船抗扭箱结构的焊接变形预控

抗扭箱作为20000TEU超大型集装箱船的关键结构,由于其组成的板材较厚且与集装箱直接接触,因此需严格控制该结构的面外焊接变形。采用基于固有变形理论的弹性有限元分析,预测抗扭箱的焊接变形,且与实际测量结果比较吻合;通过设计大厚板的非对称X型坡口来控制面外变形,结果表明：采用非对称设计的X型焊接坡口更有利于减小变形,仅需一次翻身、提高生产效率。在不考虑装配间隙时,基于高效的热-弹-塑性有限元计算归纳出超厚板(40mm~85mm)的最佳正反面坡口深度比;而考虑实际生产中的装配间隙时,最佳正反面坡口深度比与板材厚板呈非线性关系。最后将考虑装配间隙时,优化的非对称坡口焊接接头应用到抗扭箱结构中,面外焊接变形减小明显,有利于指导船厂的实际生产。     

A car-following model considering asymmetric driving behavior based on long short-term memory neural networks

Asymmetric driving behavior is a critical characteristic of human driving behaviors and has a significant impact on traffic flow. In consideration of the asymmetric driving behavior, this paper proposes a long short-term memory (LSTM) neural networks (NN) based car-following (CF) model to capture realistic traffic flow characteristics by incorporating the driving memory. The NGSIM data are used to calibrate and validate the proposed CF model. Meanwhile, three characteristics closely related to the asymmetric driving behavior are investigated: hysteresis, discrete driving, and intensity difference. The simulation results show the good performance of the proposed CF model on reproducing realistic traffic flow features. Moreover, to further demonstrate the superiority of the proposed CF model, two other CF models including recurrent neural network based CF model and asymmetric full velocity difference model, are compared with LSTM-NN model. The results reveal that LSTM-NN model can capture the asymmetric driving behavior well and outperforms other models.     

Development of signal optimization models for asymmetric two-leg continuous flow intersections

Despite extensive studies have been reported to address the operational issues of full Continuous Flow Intersection (CFI) in the literature, the asymmetric two-leg CFI, which is more applicable in practice, has not received adequate attentions yet. To satisfy such need, this study develops two signal optimization models for asymmetric CFI based on its unique geometric features. The first proposed model, following a two-step procedure, determines the cycle length, phase design and sequence, and green split in the first step and optimizes intersection offset in the second step. To benefit both intersections’ capacity maximization and signal progression design by optimizing phase plan and sequence, the second proposed model takes the Mixed-Integer-Linear-Programming (MILP) technique to concurrently optimize all signal control variables. With extensive case studies on a field site in Maryland, the simulation results prove that the proposed models can effectively provide signal progression to critical path-flows and prevent the potential queue spillover on the short turning bays/links. Further comparisons between the two proposed models reveal that the second model is more flexible in designing phase plan but the first model performs better in reducing link queue length.     

基于轨道电路解决站内分路不良方案的研究

本文首先分析了我国站内轨道电路分路不良产生的原因，然后在分析国外解决分路不良方案的基础上，结合我国实际情况，提出了几种解决分路不良切实可行的技术方案。     

非对称齿齿轮泵设计研究

针对非对称齿齿轮泵的特点进行了理论研究,推导出流量分析及流量脉动公式,并为以后该泵的国产化提供了理论基础。