Minimizing greenhouse gas emissions in intermodal freight transport: an application to rail service design

Freight transport has undesirable effects on the environment. The most prominent of these is greenhouse gas emissions. Intermodal freight transport, where freight is shipped from origin to destination by a sequence of at least two transportation modes, offers the possibility of shifting freight (either partially or in full) from one mode to another in the hope of reducing the greenhouse emissions by appropriately scheduling the services and routing the freight. Traditional planning methods for scheduling services in an intermodal transportation network usually focus on minimizing travel or time-related costs of transport. This article breaks away from such an approach by addressing the issue of incorporating environment-related costs (greenhouse gases, to be specific) into freight transportation planning and proposes an integer program in the form of a linear cost, multicommodity, capacitated network design formulation that minimizes the amount of greenhouse gas emissions of transportation activities. Computational results based on an application of the proposed approach on a real-life rail freight transportation network are presented.     

基于CVaR的危险品公铁联运路径选择研究

公铁联运在危险品的多式联运中扮演着重要角色,为了降低危险品公铁联运风险,提高危险品公铁联运的安全性,危险品公铁联运的路径选择至关重要。本文运用条件风险价值(CVaR)理论,在对危险品公铁联运网络进行变形的基础上构建了考虑决策者风险规避程度的危险品公铁联运路径选择模型,设计了求解该模型的算法,并进行了算例分析。研究结果表明:通过该模型及其算法,可根据决策者对所需运输的危险品的运输风险规避程度,在危险品公铁联运网络中快速地选出使危险品公铁联运风险最小的运输路径和运输方式;决策者的风险规避程度会对危险品公铁联运过程中的运输路径和运输方式的选择产生重要影响。     

Optimal control of road freight flows by route choice inducement: A case from Mexico

Contrasting with much of the research in freight transportation around the impacts to transport operators, this work focuses on the Road Planner providing the infrastructure. This viewpoint, seeking minimal repair costs and other payments generally conflicts with the carriers’ view, looking for the best hauling route.On a random utility frame, the user-planner interaction is modelled on a partially tolled road network, considering two types of costs: (a) lorries’ trip cost guiding the route choice, and affected by planners’ actions, and (b) planners’ road repair costs, depending on the traffic, the vehicles’ type and the control implementation. A Monte Carlo simulation bases the stochastic assignment on the network, determining optimal subsidies that divert traffic to tolled roads. On a portion of the Mexican Paved network optimal subsidies are found, increasing the toll roads’ use and reducing traffic on the non-charged roads, generally having weaker pavements and higher maintenance costs.     

Determining crane areas in intermodal transshipment yards: The yard partition problem

At rail–road transshipment yards, gantry cranes move containers from freight trains to trucks and vice versa. They constitute important entities in today’s intermodal transportation systems. Real-world yards are often partitioned into several disjunct crane areas, so that crane interferences during container transshipment are avoided. In practice, the lengths of such crane areas are typically determined by simple rules of thumb, i.e., each crane receives an equally sized area, which might result in an unleveled division of labor among cranes and, thus, prolong train processing times. This paper provides an exact solution procedure which determines disjunct yard areas of varying size for multiple gantry cranes in polynomial runtime, so that the workload for a given pulse of trains is equally distributed among cranes. Furthermore, we investigate the potential acceleration of train processing as compared to equally sized areas in a yard simulation.     

Intermodal shipments as recourse in logistics disruptions

This research deals with the flexibility of transportation systems when faced with disruptions. A network optimization model is used to investigate the feasibility of using intermodal shipments as recourse to disruptions in a transportation network. In a study of US interstate highways and intermodal rail networks, performance of over-the-road and intermodal shipments is compared under different disruption scenarios. The results show that the topology of US transportation system and locations of existing intermodal terminals provide required path redundancies and a strategic benefit for intermodal shipments to bypass disrupted regions with lower costs and competitive shipment times compared to rerouted road shipments.     

On a new class of nonlinear set covering problems arising in wireless network design

This is a summary of the author’s PhD thesis, supervised by Edoardo Amaldi and defended on 28 April 2006 at Politecnico di Milano, Dipartimento di Matematica. The thesis is written in English and is available from the author upon request. The thesis investigates a class of nonlinear set covering variants arising from the problem of designing single-frequency Wireless Local Area Networks (WLANs) with maximum efficiency. In the first part of the thesis a basic hyperbolic formulation of the problem is considered. After a complexity and approximability study, the problem is tackled by linearization techniques, and by Lagrangean and Dantzig–Wolfe decompositions. The second part of the thesis focuses on variants accounting for various relevant features of the WLAN application. A Branch-and-Price algorithm is presented, and extensions to the multiple-frequency WLAN design problem are considered.      

Data mining-based dispatching system for solving the local pickup and delivery problem

The Local Pickup and Delivery Problem (LPDP) has drawn much attention, and optimization models and algorithms have been developed to address this problem. However, for real world applications, the large-scale and dynamic nature of the problem causes difficulties in getting good solutions within acceptable time through standard optimization approaches. Meanwhile, actual dispatching solutions made by field experts in transportation companies contain embedded dispatching rules. This paper introduces a Data Mining-based Dispatching System (DMDS) to first learn dispatching rules from historical data and then generate dispatch solutions, which are shown to be as good as those generated by expert dispatchers in the intermodal freight industry. Three additional benefits of DMDS are: (1) it provides a simulation platform for strategic decision making and analysis; (2) the learned dispatching rules are valuable to combine with an optimization algorithm to improve the solution quality for LPDPs; (3) by adding optimized solutions to the training data, DMDS is capable to generate better-than-actuals solutions very quickly.     

Combining linear programming and automated planning to solve intermodal transportation problems

When dealing with transportation problems Operational Research (OR), and related areas as Artificial Intelligence (AI), have focused mostly on uni-modal transport problems. Due to the current existence of bigger international logistics companies, transportation problems are becoming increasingly more complex. One of the complexities arises from the use of intermodal transportation. Intermodal transportation reflects the combination of at least two modes of transport in a single transport chain, without a change of container for the goods. In this paper, a new hybrid approach is described which addresses complex intermodal transport problems. It combines OR techniques with AI search methods in order to obtain good quality solutions, by exploiting the benefits of both kinds of techniques. The solution has been applied to a real world problem from one of the largest spanish companies using intermodal transportation, Acciona Transmediterránea Cargo.     

Modelling and Optimal Receding-horizon Control of Maritime Container Terminals

The main objective of this paper consists in modelling, optimizing, and controlling container transfer operations inside intermodal terminals. More specifically, maritime container terminals are here considered, involving three kinds of transportation modes, i.e., maritime, rail, and road transport. Generally speaking, an intermodal port terminal can be seen as a system of container flows with two interfaces, towards the hinterland and towards the sea, respectively. Moreover, inside a terminal, unloading operations of inbound containers, container storage, and loading operations of outbound containers are carried out. A simple model for maritime container terminals is proposed in this paper. In the model, a system of queues represents the standing of containers and their movements inside the terminal. The dynamic evolutions of these queues are described by discrete-time equations, where the state variables represent the queue lengths and the control variables take into account the utilization of terminal resources such as load/unload handling rates. On the basis of the proposed model, an optimization problem is defined that consists in minimizing the transfer delays of containers in the terminal. The problem is stated as an optimal control problem whose solution is sought by adopting a receding-horizon strategy.      

A capacitated hub location problem in freight logistics multimodal networks

In this paper we deal with a capacitated hub location problem arising in a freight logistics context; in particular, we have the need of locating logistics platforms for containers travelling via road and rail. The problem is modelled on a weighed multimodal network. We give a mixed integer linear programming model for the problem, having the goal of minimizing the location and shipping costs. The proposed formulation presents some novel features for modelling capacity bounds that are given both for the candidate hub nodes and the arcs incident to them; further, the containerised origin-destination (\(o-d)\) demand can be split among several platforms and different travelling modes. Note that here the network is not fully connected and only one hub for each \(o-d\) pair is used, serving both to consolidate consignments on less transport connections and as reloading point for a modal change. Results of an extensive computational experimentation performed with randomly generated instances of different size and capacity values are reported. In the test bed designed to validate the proposed model all the instances up to 135 nodes and 20 candidate hubs are optimally solved in few seconds by the commercial solver CPLEX 12.5.     

A truck scheduling problem arising in intermodal container transportation

We address a truck scheduling problem that arises in intermodal container transportation, where containers need to be transported between customers (shippers or receivers) and container terminals (rail or maritime) and vice versa. The transportation requests are handled by a trucking company which operates several depots and a fleet of homogeneous trucks that must be routed and scheduled to minimize the total truck operating time under hard time window constraints imposed by the customers and terminals. Empty containers are considered as transportation resources and are provided by the trucking company for freight transportation. The truck scheduling problem at hand is formulated as Full-Truckload Pickup and Delivery Problem with Time Windows (FTPDPTW) and is solved by a 2-stage heuristic solution approach. This solution method was specially designed for the truck scheduling problem but can be applied to other problems as well. We assess the quality of our solution approach on several computational experiments.     

Solving scheduling problems from high-level models

This is the summary of the author??s PhD thesis supervised by Yves Deville and Pascal Van Hentenryck, and defended on 25 May 2010?at the Université catholique de Louvain in Louvain-la-Neuve. The thesis is written in English and is available from the author, or downloadable from http://becool.info.ucl.ac.be/files2/thesis-monette.pdf. This work is about the gap between high-level modelling of scheduling problems and its efficient resolution. We propose to automatically classify models of scheduling problems, and to apply an appropriate search algorithm. Thanks to the strong separation between model and search, we propose also a simple way to create hybrid algorithms. A second part of the thesis deals with Constraint Programming approaches for two scheduling problems: The one-machine non-preemptive problem and the Just-In-Time Job-Shop problem. All parts are accompanied by experimental results showing their practicality.     

Transfer distance between partitions and search of dense zones in graphs

This text summarizes the Ph.D. thesis defended by the author in November 2006 under the supervision of Olivier Hudry, at the Université Paris 1. The thesis is written in French and can be obtained from the author upon request. The first part of the thesis is mainly devoted to the study of distances between partitions, and more precisely to the transfer distance. In the second part, we design a method for overlapping clustering and we apply it to protein interactions networks.     

Stochastic hybrid simulation

This is a summary of the author’s PhD thesis supervised by Bart Scheers and Antoine Van de Capelle and defended on 20 November 2009 at the Royal Military Academy, Brussels. The thesis () is written in English and is available from the author upon request. This work deals with an extension to the hybrid simulation paradigm, i.e. the combination of event-driven simulation and analytical modelling, applied to packet telecommunication networks. In order to speed up the simulation only a small part of all packets, the foreground traffic, is processed in an event-driven way. On each arrival of a foreground packet, the waiting time of the packet is sampled from the virtual waiting time distribution function of the combined foreground and background traffic. This distribution function is stochastically modelled by the exact large deviations asymptotic of the virtual waiting time in a many sources regime. This novel methodology is not only valid for wired point-to-point queueing networks having a fixed transmission capacity, but it can also be applied to queueing networks for which the transmission capacity varies with the traffic load of all the elements in the network. The results obtained by the stochastic hybrid simulator are compared to full-blown event-driven simulations. An important reduction in simulation run-time is gained without sacrificing accuracy.     

Methods to solve multi-skill project scheduling problem

This is a summary of the author’s PhD thesis supervised by P. Martineau and E. Néron and defended on 28 November 2006 at the Université François-Rabelais de Tours. The thesis is written in French, and is available upon request from the author. This work deals with the problem of scheduling a project. The activities of this project requires skills that may not be mastered by all persons involved. First of all, the problem is defined in the introduction part. Then we propose different methods to solve it: lower bounds in part 2, different heuristics and meta-heuristics in part 3, and finally a branch-and-bound procedure in the last part.     

Some classical combinatorial problems on circulant and claw-free graphs: the isomorphism and coloring problems on circulant graphs and the stable set problem on claw-free graphs

This is a summary of the author’s Ph.D. thesis supervised by Sara Nicoloso and Gianpaolo Oriolo and defended on 3 April 2008 at Sapienza Università di Roma. The thesis is written in English and is available from the author upon request. This work deals with three classical combinatorial problems, namely the isomorphism, the vertex-coloring and the stable set problem, restricted to two graph classes, namely circulant and claw-free graphs. In the first part (joint work with Sara Nicoloso), we derive a necessary and sufficient condition to test isomorphism of circulant graphs, and give simple algorithms to solve the vertex-coloring problem on this class of graphs. In the second part (joint work with Gianpaolo Oriolo and Gautier Stauffer), we propose a new combinatorial algorithm for the maximum weighted stable set problem in claw-free graphs, and devise a robust algorithm for the same problem in the subclass of fuzzy circular interval graphs, which also provides recognition when the stability number is greater than three.     

Enhanced mixed integer programming techniques and routing problems

This is a summary of the author’s PhD thesis supervised by Andrea Lodi and Paolo Toth and defended on 16 April 2009 at the Università di Bologna. The thesis is written in English and is available from the author upon request. This work is focused on Mixed Integer Programming (MIP). In particular, the first part of the thesis deals with general purpose cutting planes, which are probably the key ingredient behind the success of the current generation of MIP solvers. The second part is instead focused on the heuristic and exact exploitation of integer programming techniques for hard combinatorial optimization problems in the context of routing applications.     

Real inversion and jump formula for the laplace transform,part II

A generalization of the Hirschman inversion formula and a new jump formula for the Laplace transform are proved. This paper is the second part of a paper with the same name (see this Journal v., 1, 1963, pp. 85–104). The notations used here are the same as in the first part. §1–§4 belong to the first part. This paper is to be a part of the first author’s Ph. D. thesis written under the direction of the second author at the Hebrew University, Jerusalem. The participation of the second author in this paper has been sponsored in part by the Air Force Office of Scientific Research, OAR, through the European Office of Aerospace Research, United States Air Force.     

Real inversion and jump formulae for the Laplace transform. Part I

Generalizations of the Laplace asymptotic method are obtained and real inversion formulae of the Post-Widder type for the Laplace transform are generalized. This paper is to be a part of the first author’s Ph.D. thesis written under the direction of the second author at The Hebrew University of Jerusalem. The participation of the second author in this paper has been sponsored in part by the Air Force Office of Scientific Research OAR through the European Office, Aerospace Research, United States Air Force.     

A review of recent research on green road freight transportation

Road freight transportation is a major contributor to carbon dioxide equivalent emissions. Reducing these emissions in transportation route planning requires an understanding of vehicle emission models and their inclusion into the existing optimization methods. This paper provides a review of recent research on green road freight transportation.