Lexi-Term : approches plurielles de la lexicographie spécialisée et de la terminologie/terminographie

Ce numéro de R.I.L.A. ‒ Rassegna Italiana di Linguistica Applicata, sur Lexi-Term : approches plurielles de la lexicographie spécialisée et de la terminologie/terminographie, naît de l’intérêt que le Groupe de Recherche Modena Lexi-Term porte à la lexicographie spécialisée, à la terminologie et à la terminographie mono- et bilingues, ainsi qu’à l’étude du comportement des termes en contexte, étroitement liée à l’analyse de corpus de textes authentiques. aduzione giuridica

Conclu* in English and Italian historical research articles

This paper integrates the tools of corpus linguistics and a more genre-oriented perspective in order to explore the lemmatizations of conclu* in the Conclusions of English and Italian research articles in history. Specifically, the main emphasis is placed on second-level Summarizers and concluders (Siepmann 2005) and the way they interact with other discourse markers and metadiscourse across moves. As will be seen, SLDMs represent a marked option,in that they add extra-meaning to their more general, more transparent, more frequent, and lessspecific counterparts. Whereas variation within the unit or pattern results from combinations with discourse markers from the same or other categories, variation across English and Italian isbetter accounted for within an interpersonal model of metadiscourse (Hyland 2004, 2008), interms of different strategies on the interactional level

Train unit scheduling guided by historic capacity provisions and passenger count surveys

Train unit scheduling concerns the assignment of train unit vehicles to cover all the journeys in a fixed timetable. Coupling and decoupling activities are allowed in order to achieve optimal utilization while satisfying passenger demands. While the scheduling methods usually assume unique and well-defined train capacity requirements, in practice most UK train operators consider different levels of capacity provisions. Those capacity provisions are normally influenced by information such as passenger count surveys, historic provisions and absolute minimums required by the authorities. In this paper, we study the problem of train unit scheduling with bi-level capacity requirements and propose a new integer multicommodity flow model based on previous research. Computational experiments on real-world data show the effectiveness of our proposed methodology

A Fast Heuristic Algorithm for the Train Unit Assignment Problem

In this paper we study a railway optimization problem known as the Train Unit Assignment Problem. A train unit consists of a self-contained train with an engine and a set of wagons with passenger seats. Given a set of timetabled train trips, each with a required number of passenger seats, and a set of train units, each with a given number of available seats, the problem calls for the best assignment of the train units to the trips, possibly combining more than one train unit for a given trip, that fulfills the seat requests. We propose a heuristic algorithm based on the computation of a lower bound obtained by solving an Integer Linear Programming model that gives the optimal solution in a "peak period" of the day. The performance of the heuristic algorithm is computationally evaluated on real-world instances provided by a regional Italian Train Operator. The results are compared with those of existing methods from the literature, showing that the new method is able to obtain solutions of good quality in much shorter computing times

A branch-and-price approach for solving the train unit scheduling problem

We propose a branch-and-price approach for solving the integer multicommodity flow model for the network-level train unit scheduling problem (TUSP). Given a train operator’s fixed timetable and a fleet of train units of different types, the TUSP aims at determining an assignment plan such that each train trip in the timetable is appropriately covered by a single or coupled train units. The TUSP is challenging due to its complex nature. Our branch-and-price approach includes a branching system with multiple branching rules for satisfying real-world requirements that are difficult to realize by linear constraints, such as unit type coupling compatibility relations and locations banned for coupling/decoupling. The approach also benefits from an adaptive node selection method, a column inheritance strategy and a feature of estimated upper bounds with node reservation functions. The branch-and-price solver designed for TUSP is capable of handling instances of up to about 500 train trips. Computational experiments were conducted based on real-world problem instances from First ScotRail. The results are satisfied by rail practitioners and are generally competitive or better than the manual ones

Recoverable Robustness for Railway Rolling Stock Planning

In this paper we explore the possibility of applying the notions of Recoverable Robustness and Price of Recoverability (introduced by [5]) to railway rolling stock planning, being interested in recoverability measures that can be computed in practice, thereby evaluating the robustness of rolling stock schedules. In order to lower bound the Price of Recoverability for any set of recovery algorithms, we consider an "optimal" recovery algorithm and propose a Benders decomposition approach to assess the Price of Recoverability for this "optimal" algorithm. We evaluate the approach on real-life rolling stock planning problems of NS, the main operator of passenger trains in the Netherlands. The preliminary results show that, thanks to Benders decomposition, our lower bound can be computed within relatively short time for our case study

Multicommodity Flow Problems with Commodity Compatibility Relations

We present a class of Multicommodity Flow Problems with Commodity Compatibility Relations (MCFP-CCR), in which compatibility relations among commodities used at each node are required. This class of problems has application in the Train Unit Scheduling Problem (TUSP) [1, 2], where train units of different traction types may not be coupled with each other to serve the same train trip. Computational complexity issues are discussed and solution methods are proposed. Computational experiments using the proposed solution methods are reported

A railway timetable rescheduling approach for handling large scale disruptions

On a daily basis, relatively large disruptions require infrastructure managers and railway operators to reschedule their railway timetables together with their rolling stock and crew schedules. This research focuses on timetable rescheduling for passenger trains at a macroscopic level in a railway network. An integer programming model is formulated for solving the timetable rescheduling problem, which minimizes the number of cancelled and delayed trains while adhering to infrastructure and rolling stock capacity constraints. The possibility of rerouting trains in order to reduce the number of cancelled and delayed trains is also considered. In addition, all stages of the disruption management process (from the start of the disruption to the time the normal situation is restored) are taken into account. Computational tests of the described model on a heavily used part of the Dutch railway network show that we are able to find optimal solutions in short computation times. This makes the approach applicable for use in practice