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  • 1. Aichholzer, Oswin
    et al.
    Akitaya, Hugo
    Cheung, Kenny
    Demaine, Erik
    Demaine, Martin
    Fekete, Sándor
    Kleist, Linda
    Kostitsyna, Irina
    Löffler, Maarten
    Masárová, Zuzana
    Mundilova, Klara
    Schmidt, Christiane
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Folding Polyominoes with Holes into a Cube2019Conference paper (Refereed)
  • 2. Aichholzer, Oswin
    et al.
    Biro, Michael
    Demaine, Erik
    Demaine, Martin
    Eppstein, David
    Fekete, Sándor P.
    Hesterberg, Adam
    Kostitsyna, Irina
    Schmidt, Christiane
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Folding Polyominoes into (Poly)CubesIn: International journal of computational geometry and applications, ISSN 0218-1959Article in journal (Refereed)
  • 3.
    Andersson Granberg, Tobias
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Polishchuk, Tatiana
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Polishchuk, Valentin
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Schmidt, Christiane
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    A Framework for Integrated Terminal Airspace Design2017Conference paper (Refereed)
  • 4.
    Andersson Granberg, Tobias
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Polishchuk, Tatiana
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Polishchuk, Valentin
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Schmidt, Christiane
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Integer Programming-Based Airspace Sectorization for Terminal Maneuvering Areas with Convex Sectors2019In: Journal of Air Transportation, E-ISSN 2380-9450, Vol. 27, no 4Article in journal (Refereed)
    Abstract [en]

    In this paper an airspace sectorization framework for terminal maneuvering areas based on mixed integer programming is presented. It incorporates an airspace complexity representation, as well as various constraints on the sectors’ geometry, for example, the requirement that points demanding increased attention from air traffic controllers should lie in the sector’s interior to allow for enough time to resolve possible conflicts. The method can enforce convex sectors. In contrast to earlier integer/constraint programming approaches, which used synthesis methods with variables per elementary airspace piece that were glued together to form sectors, the integer programming formulation uses a variable per potential edge on the sector boundary. It is also the first step toward an integrated design of routes, the resulting complexity, and a sectorization. This paper presents results for Stockholm Arlanda airport and compares the integer programming results to convex sectorizations obtained by enumerating all possible topologies for a given number of sectors. This yields a proof-of-concept for the application of this highly flexible approach to terminal maneuvering areas.

  • 5.
    Cannon, Sarah
    et al.
    College of Computing, Georgia Institute of Technology, Atlanta, USA.
    Fai, Thomas
    Paulson School of Engineering and Applied Sciences, Harvard University, MA, USA.
    Iwerks, Justin
    Mathematics Department, The Spence School, NY, USA.
    Leopold, Undine
    Mathematics Department, Technische Universität Chemnitz, Germany.
    Schmidt, Christiane
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Combinatorics and complexity of guarding polygons with edge and point 2-transmitters2018In: Computational geometry, ISSN 0925-7721, E-ISSN 1879-081X, Vol. 68, p. 89-100Article in journal (Refereed)
    Abstract [en]

    We consider a generalization of the classical Art Gallery Problem, where instead of a light source, the guards, called k-transmitters, model a wireless device with a signal that can pass through at most k walls. We show it is NP-hard to compute a minimum cover of point 2-transmitters, point k-transmitters, and edge 2-transmitters in a simple polygon. The point 2-transmitter result extends to orthogonal polygons. In addition, we give necessity and sufficiency results for the number of edge 2-transmitters in general, monotone, orthogonal monotone, and orthogonal polygons.

  • 6.
    Daescu, Ovidiu
    et al.
    University of Texas at Dallas, Richardson, TX, USA.
    Friedrichs, Stephan
    Max Planck Institute for Informatics, Saarbrücken, Germany; Saarbrücken Graduate School of Computer Science, Saarbrücken, Germany.
    Malik, Hemant
    University of Texas at Dallas, Richardson, TX, USA.
    Polishchuk, Valentin
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Schmidt, Christiane
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Altitude Terrain Guarding and Guarding Uni-Monotone Polygons2019In: Computational geometry, ISSN 0925-7721, E-ISSN 1879-081XArticle in journal (Refereed)
    Abstract [en]

    We present an optimal, linear-time algorithm for the following version of terrain guarding: given a 1.5D terrain and a horizontal line, place the minimum number of guards on the line to see all of the terrain. We prove that the cardinality of the minimum guard set coincides with the cardinality of a maximum number of “witnesses”, i.e., terrain points, no two of which can be seen by a single guard. We show that our results also apply to the Art Gallery problem in “monotone mountains”, i.e., x-monotone polygons with a single edge as one of the boundary chains. This means that any monotone mountain is “perfect” (its guarding number is the same as its witness number); we thus establish the first non-trivial class of perfect polygons.

  • 7.
    Dahlberg, Joen
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Polishchuk, Tatiana
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Polishchuk, Valentin
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Schmidt, Christiane
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Stakeholder Cooperation for Improved Predictability and Lower Cost Remote Services2017Conference paper (Refereed)
  • 8.
    Friedrichs, Stephan
    et al.
    Max Planck Institute for Informatics, Germany; Saarbrucken Graduate School of Computer Science, Germany.
    Hemmer, Michael
    TU Braunschweig, IBR, Algorithms Group, Braunschweig, Germany.
    King, James
    D-Wave Systems, Burnaby, Canada.
    Schmidt, Christiane
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    The continuous 1.5D terrain guarding problem: Discretization, optimal solutions, and PTAS2016In: Journal of Computational Geometry, ISSN 1920-180X, E-ISSN 1920-180X, Vol. 7, no 1, p. 256-284Article in journal (Refereed)
    Abstract [en]

    In the NP-hard continuous 1.5D Terrain Guarding Problem (TGP) we are given an xx-monotone chain of line segments in R2 (the terrain TT), and ask for the minimum number of guards (located anywhere on TT) required to guard all of TT. We construct guard candidate and witness sets G,W⊂T of polynomial size such that any feasible (optimal) guard cover G∗⊆Gfor WW is also feasible (optimal) for the continuous TGP. This discretization allows us to: (1) settle NP-completeness for the continuous TGP; (2) provide a Polynomial Time Approximation Scheme (PTAS) for the continuous TGP using the PTAS for the discrete TGP by Gibson et al.; (3) formulate the continuous TGP as an Integer Linear Program (IP). Furthermore, we propose several filtering techniques reducing the size of our discretization, allowing us to devise an efficient IP-based algorithm that reliably provides optimal guard placements for terrains with up to 10^6 vertices within minutes on a standard desktop computer.

  • 9. Friedrichs, Stephan
    et al.
    Polishchuk, Valentin
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Schmidt, Christiane
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Altitude Terrain Guarding and Guarding Uni-Monotone Polygons2018Conference paper (Refereed)
  • 10.
    Josefsson, Billy
    et al.
    LFV.
    Jakobi, Joern
    DLR.
    Papenfuss, Anne
    DLR.
    Polishchuk, Tatiana
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering. Ms..
    Schmidt, Christiane
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Sedov, Leonid
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Identification of Complexity Factors for Remote Towers2018In: SESAR Innovation Days, 2018Conference paper (Refereed)
  • 11.
    Josefsson, Billy
    et al.
    ATCO, Manager, Automation and Human Performance, LFV Research and Innovation, Norrköping, Sweden.
    Polishchuk, Tatiana
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Polishchuk, Valentin
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Schmidt, Christiane
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    A Step Towards Remote Tower Center Deployment: Optimizing Staff Scheduling2019In: Journal of Air Transportation, E-ISSN 2380-9450, Vol. 27, no 3Article in journal (Refereed)
    Abstract [en]

    Remote tower service is one of the technological and operational solutions delivered for deployment by the Single European Sky Air Traffic Management Research Program. This new concept fundamentally changes how operators provide air traffic services as it becomes possible to control several airports from a single remote center. In such settings, an air traffic controller works at a so-called multiple position in the remote center; that is, he/she handles two or more airports from one remote tower module, that is, the controller working position. In this paper, an optimization framework is presented for traffic management at five Swedish airports that were chosen for remote operation using a remote tower center designed to serve a number of airports. The problems experienced with real airport schedules are highlighted, and optimal assignments of the airports to the remote tower modules are presented. Both scheduled traffic and special (nonscheduled) traffic at these five airports are considered.

  • 12.
    Ljunggren, Fredrik
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering. Trafikverket.
    Persson, Kristian
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering. Sweco.
    Peterson, Anders
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Schmidt, Christiane
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Maximum Robust Train Path for an Additional Train Inserted in an Existing Railway Timetable2018Conference paper (Other academic)
    Abstract [en]

    We present an algorithm to insert a train path in an existing railway timetable close to operation, when we want to affect the existing (passenger) traffic as little as possible. Thus, we consider all other trains as fixed, and aim for a resulting train path that maximizes the bottleneck robustness. Our algorithm is based on a graph formulation of the problem and uses a variant of Dijkstra's algorithm.

    We present an extensive experimental evaluation of our algorithm for the Swedish railway stretch from Malmö to Hallsberg. Moreover, we analyze the size of our constructed graph.

  • 13.
    Peterson, Anders
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Polishchuk, Valentin
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Schmidt, Christiane
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Applying Geometric Thick Paths to Compute the Maximum Number of Additional Train Paths in a Railway Timetable2019Conference paper (Refereed)
  • 14.
    Sáez, Raul
    et al.
    UPC Barcelona.
    Prats, Xavier
    UPC Barcelona.
    Polishchuk, Tatiana
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Polishchuk, Valentin
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Schmidt, Christiane
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Automation for Separation with CDOs: Dynamic Aircraft Arrival Routes2019Conference paper (Refereed)
  • 15.
    Wahlborg, Magnus
    et al.
    Swedish Transport Administration (Trafikverket), Borlänge, Sweden.
    Peterson, Anders
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Gruosso, Lucia
    Ansaldo STS, Genova, Italy.
    Schmidt, Christiane
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Jalili, Leila
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    D3.1 – Final pre-study for an improved methodology for timetable planning including state-of-the-art and future work plan2018Report (Other academic)
    Abstract [en]

    In ARCC project work package 3, research and innovation activities have been done to identify areas with a need for improved timetable planning methods and outline how new methods can be developed and implemented.

    Improved timetable planning scope were described and there was an activity to connect to other relevant Shift2Rail projects. An workshop was organised in Stockholm 2018-05-29.

    State of the art in practice was described for timetable planning in Sweden, UIC 406 method and Ansaldo STS Traffic management systems. Also state of the art in algorithms was described.

    Future work plan research needs areas are:

    1. Understanding of various goals for timetabling and how they co-variate

    2. Residual capacity

    3. Connection and coordination of the planning processes

    4. Connection and coordination of the yard/terminal planning and network planning

    5. Integration of freight trains into the timetable, focusing on short-term and ad-hoc

    6. Integration of maintenance scheduling and timetabling, at all planning stages

    7. Improved decision support for handeling of deviations from timetable in operations

    8. Features of planning tools, and implementation of automatized timetabling

1 - 15 of 15
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