A dynamic model for marginal cost pricing of port infrastructures

ABSTRACT

A dynamic model for marginal cost pricing of port infrastructures links costs to system performance by combining a power-law function with time-dependent queueing analysis. Additionally, the model incorporates the marginal cost of capacity, including the effects of economies of scale. This allows the calculation of the marginal cost price under a dynamic framework. The model accounts for nonlinear behaviour of port demand, which is sensitive to price and service levels. The effects over time of cost and service levels on the port’s operational performance are quantified. The proposed model allows determining the optimal timing for capacity investment. The model is a starting point for the application of marginal cost pricing to ports. However, for practical application of such pricing method it is necessary to apply a system’s approach, as productivity and costs must be assessed at the terminal’s component level. This should allow the derivation of a marginal cost function at the terminal’s component level.     

基于船舶领域和MMG的最晚施舵点/CRI研究

提出了一种基于MMG和船舶领域的LSP计算模型,以及改进的空间碰撞危险度（space collision risk index,SCRI）/时间碰撞危险度（time collision risk index,TCRI）模型,并进行了计算机仿真.结果表明：水动力模型精度可满足研究与实践要求;基于二分法的LSP模型能快速、可靠收敛;LSP和SCRI/TCRI模型更符合海员通常做法和避碰规则的公认理解.     

互通立交匝道端部纵断面设计探讨

匝道纵断面设计是互通立交设计中的重要一环,尤其是位于匝道起终点端部处的设计高程及设计坡度的计算更是其中一大难点.笔者根据多年设计经验,结合现有规范,对这一难点进行分析,并提出一种新的设计思路以供参考.     

出海路祖山至马蹄岭段路况调查

出海路祖山至马蹄岭段主要为水泥混凝土路面,路段经过12年的运营各种病害发展迅速.2012年4月通过咨询、调查、收集、测试等手段,对该路段气象水文、交通组成、养护维修历史、路面结构、路面检测指标、路面病害种类、桥涵情况进行了详细调查,获得了真实可靠的资料,为大修方案的确定提供了依据.     

Modeling the behavioral determinants of travel behavior: An application of latent transition analysis

This paper applies the relatively new method of latent class transition analysis to explore the notion that qualitative differences in travel behavior patterns are substantively meaningful and therefore relevant from explanatory point of view. For example, because the bicycle may function as an important access and egress mode, a car user who also (occasionally) uses the bicycle may be more likely to switch to a public transit profile than someone who only uses the car. Data from the Dutch mobility panel are used to inductively reveal travel behavior patterns and model transitions in these patterns over time. Additionally, the effects of seven exogenous variables, including two important life events (i.e. moving house and changing jobs), on cluster membership and the transition probabilities are assessed. The results show that multiple-mode users compared to single-mode users are more likely to switch from one behavioral profile to another. In addition, age, the residential environment, moving house and changing jobs have strong influences on the transition probabilities between the revealed behavioral patterns over time.     

山前区云母石英片岩风化层滑坡分析与治理

结合合福铁路某滑坡,从地形、地质特征、地下水、地表降水等特点综合分析该滑坡的形成机理,确立滑坡体的合理滑面、规模,并结合滑坡体特征采用减载、支挡防护及排水治理方案进行综合整治。研究结果:通过施工完成后近1年的变形监测及雨季检验,该滑坡体整体稳定。研究结论:对于山前区云母石英片岩风化层滑坡,应该从地形、地质特征及降水等角度合理确定滑坡体的性质,并采取有针对性的加固措施。     

霍金的意义:上帝、外星人和世界的真实性

本文从新的视角考察了霍金最近发表的两条引起媒体极大兴趣的言论:关于宇宙是不是上帝创造的,关于我们要不要和外星文明交往,以及他另一个不太受关注的依赖模型的实在论观点,得出结论认为霍金在这些重要问题上其实并没有提供新的立场,只是完成了站队,但由于他的科学之神的传奇身份和影响,霍金却能通过老生常谈为人类做出新的贡献。本文还认为,霍金的新作《大设计》可能是他最后的学术遗嘱。     

Verifying liner Shipping Alliance’s stability by applying core theory

The core is a vital concept in cooperative game theory and has been widely used in analyzing alliance’s stability. It is especially interesting to apply core theory in liner shipping market due to the latter’s exceptional characteristic of non-homogeneous cost curves as well as divisible and fluctuant demand. Having observed some new phenomena and trends in the industry, this paper studies the economic performance and stability of liner shipping alliance by applying core theory where business cooperation is partly realized by delivering joint-service with mega container ships. To demonstrate the core situation in liner shipping alliance, a cost function is first identified on the basis of two assumptions regarding cooperation: 1) sharing or pooling vessels and 2) deploying mega container ships if needed. Taking cost functions as basis, two conditions of approaching core may be groomed, i.e., collective rationality and individual rationality. The first condition is discussed from the perspective of market, while the second condition is studied within the alliance. Stability of liner shipping alliance is then observed based on these two conditions. An illustrative case study is conducted in order to show some implications and explicitly clarify the theory.     

外倾式非对称曲线拱桥力学特性分析

针对一座外倾式非对称钢箱拱桥,通过利用桥梁结构专业软件Midas/civil建立其空间杆系有限元模型进行整体受力性能分析,探讨主要受力结构拱肋、吊杆以及钢箱主梁的力学特点;并通过外倾角的改变研究分析了吊杆内力随拱肋外倾角改变的变化规律,对于完善该类异型拱桥的设计理论、工程施工,确保结构安全、设计合理等方面都有一定的参考价值。     

Using automated walking gait analysis for the identification of pedestrian attributes

Collecting microscopic pedestrian behavior and characteristics data is important for optimizing the design of pedestrian facilities for safety, efficiency, and comfortability. This paper provides a framework for the automated classification of pedestrian attributes such as age and gender based on information extracted from their walking gait behavior. The framework extends earlier work on the automated analysis of gait parameters to include analysis of the gait acceleration data which can enable the quantification of the variability, rhythmic pattern and stability of pedestrian’s gait. In this framework, computer vision techniques are used for the automatic detection and tracking of pedestrians in an open environment resulting in pedestrian trajectories and the speed and acceleration dynamic profiles. A collection of gait features are then derived from those dynamic profiles and used for the classification of pedestrian attributes. The gait features include conventional gait parameters such as gait length and frequency and dynamic parameters related to gait variations and stability measures. Two different techniques are used for the classification: a supervised k-Nearest Neighbors (k-NN) algorithm and a newly developed semi-supervised spectral clustering. The classification framework is demonstrated with two case studies from Vancouver, British Columbia and Oakland, California. The results show the superiority of features sets including gait variations and stability measures over features relying only on conventional gait parameters. For gender, correct classification rates (CCR) of 80% and 94% were achieved for the Vancouver and Oakland case studies, respectively. The classification accuracy for gender was higher in the Oakland case which only considered pedestrians walking alone. Pedestrian age classification resulted in a CCR of 90% for the Oakland case study.