Train routing and timetabling problem for heterogeneous train traffic with switchable scheduling rules

This paper proposes a mathematical model for the train routing and timetabling problem that allows a train to occasionally switch to the opposite track when it is not occupied, which we define it as switchable scheduling rule. The layouts of stations are taken into account in the proposed mathematical model to avoid head-on and rear-end collisions in stations. In this paper, train timetable could be scheduled by three different scheduling rules, i.e., no switchable scheduling rule (No-SSR) which allows trains switching track neither at stations and segments, incomplete switchable scheduling rule (In-SSR) which allows trains switching track at stations but not at segments, and complete switchable scheduling rule (Co-SSR) which allows trains switching track both at stations and segments. Numerical experiments are carried out on a small-scale railway corridor and a large-scale railway corridor based on Beijing–Shanghai high-speed railway (HSR) corridor respectively. The results of case studies indicate that Co-SSR outperforms the other two scheduling rules. It is also found that the proposed model can improve train operational efficiency.     

Closed-loop Inventory Routing Problem for returnable transport items

Increasing concerns on supply chain sustainability have given birth to the concept of closed-loop supply chain. Closed-loop supply chains include the return processes besides forward flows to recover the value from the customers or end-users. Vendor Managed Inventory (VMI) systems ensure collaborative relationships between a vendor and a set of customers. In such systems, the vendor takes on the responsibility of product deliveries and inventory management at customers. Product deliveries also include reverse flows of returnable transport items. The execution of the VMI policy requires vendor to deal with a Closed-loop Inventory Routing Problem (CIRP) consisting of its own forward and backward routing decisions, and inventory decisions of customers. In CIRP literature, traditional assumptions of disregarding reverse logistic operations, knowing beforehand distribution costs between nodes and customers demand, and managing single product restrict the usage of the proposed models in current food logistics systems. From this point of view, the aim of this research is to enhance the traditional models for the CIRP to make them more useful for the decision makers in closed-loop supply chains. Therefore, we propose a probabilistic mixed-integer linear programming model for the CIRP that accounts for forward and reverse logistics operations, explicit fuel consumption, demand uncertainty and multiple products. A case study on the distribution operations of a soft drink company shows the applicability of the model to a real-life problem. The results suggest that the proposed model can achieve significant savings in total cost and thus offers better support to decision makers.     

浅谈船舶定线制在长江尹公洲航段的深化实施

文中通过分析尹公洲航段的复杂环境及航路航法，分析造成尹公洲航段事故多发的主要原因并探讨解决的方法。     

A Secure Multi-Routing Platform for Ad Hoc Network

In an ad hoc network, it is usually difficult to optimize the assignment of network routing resources using a single type of routing protocol due to the differences in network scale, node moving mode and node distribution. Therefore, it is desirable to have nodes run multiple routing protocols simultaneously so that more than one protocols can be chosen to work jointly. For this purpose,a multiple routing platform for Ad hoc networks is proposed on a higher level of current routing protocols. In order to ensure the security of the platform, a security mechanism and its formal analysis by BAN logic is given. The simulation results of the network performance demonstrate that the proposed multi-routing platform is practicable in some complex applications.     

Book reviews

THE U.S. AIRFREIGHT INDUSTRY, by Nawal K. Taneja. Lexington Books, Lexington, Mass., 1979. 244 pp.

TRAFFIC, OPERATIONAL RESEARCH, FUTUROLOGY, by Arne Jensen. North Holland Publishing Company, Amsterdam, 1980. 321 pp. ($39.00)

PROBLEMS OF THE CARLESS, by R. E. Paaswell and W. W. Recker. Praeger Publishers, New York, 1978. 190 pp.

TRANSPORTATION AND THE ELDERLY, by Martin Wachs. University of California Press, Berkeley, 1980.

PUBLIC TRANSPORTATION: PLANNING, OPERATIONS AND MANAGEMENT, edited by George E. Gray and Lester A Hoel. Prentice Hall, Englewood Cliffs, New Jersey, 1979. 749 pp.

ETHYL ALCOHOL PRODUCTION AND USE AS A MOTOR FUEL, edited by J. K. Paul. Noyes Data Corporation, New Jersy, 1979. 354 pp ($48.00).

URBAN PLANNING AND PUBLIC TRANSPORT, edited by Roy Cresswell. The Construction Press, London, 1980. 172 pp. (£15.00)     

Dynamic routing-and-inventory problems: a review

The paper presents a review of the available literature on a class of problems denoted as dynamic routing-and-inventory (DRAl) problems. They are characterized by the simultaneous relevance of routing and of inventory issues in a dynamic environment, within the framework of distribution logistics. A classification scheme is first proposed for these problems. Then the results obtained in this area are summarized. Finally, the papers available in the literature are clustered and discussed according to the proposed scheme.     

Optimum routing of a sailing wind farm

To acquire the wind energy of the oceans, a sailing wind farm has been proposed. The wind farm considered is composed of a semisubmersible floating structure, 11 windmills, four sails, six thrusters, and storage for hydrogen. To maximize the acquired energy, an effective algorithm to search for optimum routes was developed. The algorithm is based on the fact that beam winds yield a maximum of acquired energy. This feature reduces the computation time, and, consequently, efficient route optimization becomes possible in a reasonable time. After setting an operational area for the wind farm, navigation simulations for a 1-year period were carried out. A numerical weather forecast was used as well as the responses of the floating structure, such as the speed of the structure, the output power of the windmills, and the time of course changes. In the simulation, the wind farm evades rough seas to avoid structural damage, and an optimum route is searched for. The capacity factor of the system was used to evaluate the efficiency of the optimized routes. From the simulations, the maximum capacity factor achieved was 42.6%. The dependency of the capacity factor on the initial position of the wind farm was also examined. It was shown that offshore from Sanriku in northeastern Japan is an area suited to the operation of the wind farm. The effect of the initial position on consecutive periods of operation is discussed.     

Floating car based travel times for city logistics

City logistics routing requires time-dependent travel times for each network link. We rely on the concept of Floating Car Data (FCD) to develop and provide such travel times. Different levels of aggregation in the determination of time-dependent travel times from a database of historical FCD are presented and evaluated with regard to routing quality. Furthermore, a Data Mining approach is introduced, allowing for a substantial reduction of the volume of input data required for city logistics routing. The different approaches are investigated and evaluated by a huge amount of FCD collected for the urban area of Stuttgart, Germany. The results show that the Data Mining approach enables efficient provision of time-dependent travel times without a significant loss of routing quality for city logistics applications.     

TXJK型驼峰信号溜放进路自动控制系统

介绍ＴＸＪＫ驼峰信号溜放进路自动控制系统的结构，功能及特点。     

A dynamic behavioural traffic assignment model with strategic agents

Foresee traffic conditions and demand is a major issue nowadays that is very often approached using simulation tools. The aim of this work is to propose an innovative strategy to tackle such problem, relying on the presentation and analysis of a behavioural dynamic traffic assignment.The proposal relies on the assumption that travellers take routing policies rather than paths, leading us to introduce the possibility for each simulated agent to apply, in real time, a strategy allowing him to possibly re-route his path depending on the perceived local traffic conditions, jam and/or time already spent in his journey.The re-routing process allows the agents to directly react to any change in the road network. For the sake of simplicity, the agents’ strategy is modelled with a simple neural network whose parameters are determined during a preliminary training stage. The inputs of such neural network read the local information about the route network and the output gives the action to undertake: stay on the same path or modify it. As the agents use only local information, the overall network topology does not really matter, thus the strategy is able to cope with large and not previously explored networks.Numerical experiments are performed on various scenarios containing different proportions of trained strategic agents, agents with random strategies and non strategic agents, to test the robustness and adaptability to new environments and varying network conditions. The methodology is also compared against existing approaches and real world data. The outcome of the experiments suggest that this work-in-progress already produces encouraging results in terms of accuracy and computational efficiency. This indicates that the proposed approach has the potential to provide better tools to investigate and forecast drivers’ choice behaviours. Eventually these tools can improve the delivery and efficiency of traffic information to the drivers.