Routing and fleet deployment in liner shipping with spot voyages

The routing, scheduling and fleet deployment is an important integrated planning problem faced by liner shipping companies which also lift load from the spot market. This paper is concerned with coordinating the decisions of the assignment of ships to contractual and spot voyages, and the determination of ship routes and schedules in order to maximize profit. We propose a new model for representing voyages as nodes of a directed graph which is used to build a mixed integer programming formulation. Besides contractual and spot nodes, another type of node is put forward to represent a combination of a contractual voyage with one or more spot voyages. In addition, the concept of dominated nodes is introduced in order to discard them and reduce the effort of the search for an optimal solution. A set of test problems has been generated taking into account real world assumptions. The test problems are solved by an optimization software and computational results are reported. The results show the potential of the approach to solve test problems of moderate size.     

What Does Happen to Our Driving When We Get Older?

Abstract

The objective of this paper is to uncover the main antecedents associated with driving errors among older drivers in order to establish a framework for analyzing potential skill improvements using other approaches, for example, games. The article also aims at classifying age-related declines in seniors' abilities associated with their driving performance. The research undertakes an analysis of attempts made through the investigation of the literature. We have systematically searched papers and extracted (1) prevalent driving errors among seniors and (2) underlying age-related declines in seniors' abilities associated with their driving performance. We have also identified some characteristics of the research in this area (e.g. the research methods and geographical distribution of the research). Our expert panel mapped the functional declines in seniors' abilities to the driving errors to identify the relationship between these findings. A reliability test resulted in 81% reliability of findings. We have identified eight groups of driving errors, which could be affected by physical, visual, and cognitive declines among seniors. According to the experts' opinions, the underlying relationship of physical, visual, and cognitive declines among seniors and their driving errors were also presented. Our findings show that there is a potential for the use of innovative interventions such as playing video games to create an inexpensive, motivational, and enjoyable method that may provide a transfer effect to specific driving skills. This could help improve seniors' driving performance by improving specific functional abilities associated with driving.     

A bi-level model of dynamic traffic signal control with continuum approximation

This paper proposes a bi-level model for traffic network signal control, which is formulated as a dynamic Stackelberg game and solved as a mathematical program with equilibrium constraints (MPEC). The lower-level problem is a dynamic user equilibrium (DUE) with embedded dynamic network loading (DNL) sub-problem based on the LWR model (Lighthill and Whitham, 1955; Richards, 1956). The upper-level decision variables are (time-varying) signal green splits with the objective of minimizing network-wide travel cost. Unlike most existing literature which mainly use an on-and-off (binary) representation of the signal controls, we employ a continuum signal model recently proposed and analyzed in Han et al. (2014), which aims at describing and predicting the aggregate behavior that exists at signalized intersections without relying on distinct signal phases. Advantages of this continuum signal model include fewer integer variables, less restrictive constraints on the time steps, and higher decision resolution. It simplifies the modeling representation of large-scale urban traffic networks with the benefit of improved computational efficiency in simulation or optimization. We present, for the LWR-based DNL model that explicitly captures vehicle spillback, an in-depth study on the implementation of the continuum signal model, as its approximation accuracy depends on a number of factors and may deteriorate greatly under certain conditions. The proposed MPEC is solved on two test networks with three metaheuristic methods. Parallel computing is employed to significantly accelerate the solution procedure.     

基于非合作博弈的不同公共交通方式间的定价方法

不同的公共交通方式之间是既竞争又互补的关系,其定价策略既要受到竞争对手的影响,又要受到政府限价的影响。采用MNL交通方式选择模型、收益函数模型和非合作博弈模型结合的方式研究不同公共交通方式间的均衡定价策略,提出了定价方法。     

采用博弈思想对暗标投标进行分析

招投标机制的建立,使得招标过程中,投标人与投标人之间、招标人与投标人之间都存在着博弈行为。在密封投标(暗标投标)条件下,利用博弈论思想及模型对招投标及密封投标进行了分析,以供参考。     

A network wide simulation strategy of alternative fuel vehicles

This paper presents an integrated simulator “CUIntegration” to evaluate routing strategies based on energy and/or traffic measures of effectiveness for any Alternative Fuel Vehicles (AFVs). The CUIntegration can integrate vehicle models of conventional vehicles as well as AFVs developed with MATLAB-Simulink, and a roadway network model developed with traffic microscopic simulation software VISSIM. The architecture of this simulator is discussed in this paper along with a case study in which the simulator was utilized for evaluating a routing strategy for Plug-in Hybrid Electric Vehicles (PHEVs) and Electric Vehicles (EVs). The authors developed a route optimization algorithm to guide an AFV based on that AFV driver’s choice, which included; finding a route with minimum (1) travel time, (2) energy consumption or (3) a combination of both. The Application Programming Interface (API) was developed using Visual Basic to simulate the vehicle models/algorithms developed in MATLAB and direct vehicles in a roadway network model developed in VISSIM accordingly. The case study included a section of Interstate 83 in Baltimore, Maryland, which was modeled, calibrated and validated. The authors considered a worst-case scenario with an incident on the main route blocking all lanes for 30 min. The PHEVs and EVs were represented by integrating the MATLAB-Simulink vehicle models with the traffic simulator. The CUIntegration successfully combined vehicle models with a roadway traffic network model to support a routing strategy for PHEVs and EVs. Simulation experiments with CUIntegration revealed that routing of PHEVs resulted in cost savings of about 29% when optimized for the energy consumption, and for the same optimization objective, routing of EVs resulted in about 64% savings.     

铁路改制后关于铁路客运票价制定的博弈分析

铁路票价的高低是影响铁路经济效益的重要因素。文中分析现行铁路客票体系存在的问题,并用博弈论方法对铁路票价制定和消费者购买行为进行经济学分析,从铁路客流呈现季节性变化的角度出发,将铁路客票价格按照节假日和非节似H两个模型进行博弈分析,对未来铁路票价的合理制定提供依据,并给予相应的建议。     

基于博弈的无线Mesh网络高效可靠路由算法

由于无线网络节点自身资源有限,末端节点往往会表现出自私行为以保证其生存时间和工作效率.针对这些特点提出了一种基于博弈的能量容忍策略（ETS）模型,该模型在经典针锋相对（TFT）策略的基础上,加入合作度及能量容忍因子,宽容节点一定程度的自私行为,并给予自私节点改过自新的机会,使其能够恢复合作.同时,基于ETS设计一种路由激励机制,通过奖惩激励自私节点放弃自私行为,并对能量相对较低的节点进行保护,在一定程度上避免个别繁忙节点过度消耗,均衡网络能量,延长了网络的运行时间.实验表明ETS激励机制在防止节点自私行为、优化网络吞吐率和网络生存时间方面等表现出较好的性能优势.     

大体积混凝土高桩墩台的施工设计

高桩墩台是码头施工的重点控制工序,因其抵御风险能力差,模板设计的成功与否决定其成败。文章由成功的工程实例,系统分析了墩台模板设计、施工的全过程,探讨以安全为首要设计控制,通过以对策分析为基础的施工设计,结构构造设计,以强度、刚度验算和重点部位抗剪验算为基础的计算设计等三个步骤进行施工模型设计的方法。依此方法进行模板设计和工艺安排,工序控制合理,未出现任何危险情况,交工质量优良,并降低了施工成本,保证了工程提前竣工。     

基于市场进入博弈的高速铁路与航空竞争分析

提出了一个市场进入博弈模型来研究高铁和航空在中等运输距离上的竞争，重点考虑了票价、服务频率和乘客在不同交通方式之间因价格变动产生的转移等因素. 作为市场在位者，航空有允许和阻止两种策略，而高铁可以选择进入或者不进入市场，运用逆向归纳法求解出各种策略组合下航空和高铁的最佳策略，通过京沪高铁的实例展示了航空和高铁博弈的结果，给出了博弈双方的利润、票价、服务频率，以及在市场需求变动、机型变动和沉没成本变动条件下三者的变动情况. 结果表明，如果高铁的沉没成本不高并且市场需求充足，其最佳策略是进入市场，而航空的最佳策略是允许.