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  • 1.
    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 design2019In: Aeronautical Journal, ISSN 0001-9240, Vol. 123, no 1263, p. 567-585Article in journal (Refereed)
    Abstract [en]

    Route planning and airspace sectorisation are two central tasks in air traffic management. Traditionally, the routing and sectorisation problems were considered separately, with aircraft trajectories serving as input to the sectorisation problem and, reciprocally, sectors being part of the input to the path finding algorithms. In this paper we propose a simultaneous design of routes and sectors for a transition airspace. We compare two approaches for this integrated design: one based on mixed integer programming, and one Voronoi-based model that separates potential "hotspots" of controller activity resulting from the terminal routes. We apply our two approaches to the design of Stockholm Terminal Maneuvering Area.

  • 2.
    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.

  • 3.
    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.

  • 4.
    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)
  • 5.
    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)
  • 6.
    Peterson, Anders
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Wahlborg, Magnus
    Railway Traffic and sale, Trafikverket, Borlänge.
    Häll, Carl Henrik
    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.
    Kordnejad, Behzad
    Transportplanering, Royal Institute of Technology (KTH), Stockholm, Sweden.
    Warg, Jennifer
    Transportplanering, Royal Institute of Technology (KTH), Stockholm, Sweden.
    Johansson, Ingrid
    Transportplanering, Royal Institute of Technology (KTH), Stockholm, Sweden.
    Joborn, Martin
    Systems Engineering, RISE Research Institutes of Sweden, Göteborg, Sweden.
    Gestrelius, Sara
    Systems Engineering, RISE Research Institutes of Sweden, Göteborg, Sweden.
    Törnquist Krasemann, Johanna
    Department of Computer Science, Blekinge tekniska högskola, Karlskrona, Sweden.
    Josyula, Sai Prashanth
    Department of Computer Science, Blekinge tekniska högskola, Karlskrona, Sweden.
    Palmqvist, Carl-William
    Transport Systems and Logistics, Lund University, Sweden.
    Lidén, Tomas
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering. Swedish National Road and Transport Research Institute (VTI), Linköping, Sweden.
    Deliverable D 3.1: Analysis of the gap between daily timetable and operational traffic2019Report (Other academic)
    Abstract [en]

    Fr8Rail II/Work-Package 3 Real-time network management and improved methods for timetable planning addresses the problem to improve capacity and punctuality in the railway system by developing concepts and methods for tactical planning and operational traffic. In this report the state-of-the-art has been summarised.

    The aim of the project is to:

    • Propose concepts and methods that improve the annual and short-term timetable planning.
    • Demonstrate how the proposed timetable planning concepts improve the prerequisites for real-time network management.
    • Develop methods and tools that can reduce inefficiencies in real time network management.

    An important aspect is to improve the coordination between yards/terminals and the line network, and between Infrastructure Manager, Yard Managers, and freight Rail Undertakings.

    We motivate our research by the current situation in Sweden, which is characterised by low on-time performance for freight trains, dense and heterogenous traffic on the major railway lines, and a rigid annual timetabling process, which is non-suitable for short-term changes. We believe that better tools for network planning and management on tactical and operational level can help to connect planning and operational processes.

    Aiming for improvements of the operational traffic, there is a need for systematic development of methods applied at several planning horizons, based on both simulation and optimization techniques. Close to operation fast methods are needed, for example, based on meta-heuristics.

    The maintenance planning process and improvement potential have been described. This is a new piece of the puzzle and it is important to close the gap between timetable planning and operational traffic. The different planning processes at the Infrastructure Manager, the Rail Undertakings and the Maintenance Contractors should be aligned.

    When developing new approaches for computational decision-support tools for real-time network management, it is important — but very challenging — to evaluate and benchmark with existing software tools. We also observe that the research stream on computational decision-support and algorithm development for railway traffic management has not yet been sufficiently merged with the corresponding research stream focusing on aspects of human computer interaction.

  • 7. 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)
  • 8.
    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.

  • 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.
    Dahlberg, Joen
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Andersson Granberg, Tobias
    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.
    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.
    Capacity-Driven Automatic Design of Dynamic Aircraft Arrival Routes2018In: 2018 IEEE/AIAA 37TH DIGITAL AVIONICS SYSTEMS CONFERENCE (DASC), IEEE , 2018, p. 1194-1202Conference paper (Refereed)
    Abstract [en]

    We present a Mixed-Integer Programming framework for the design of aircraft arrival routes in a Terminal Maneuvering Area (TMA) that guarantee temporal separation of aircraft. The output routes constitute operationally feasible merge trees, and guarantee that the overall traffic pattern in the TMA can be monitored by air traffic controllers; in particular, we ensure that all aircraft on the arrival routes are separated in time and all merge points are spatially separated. We present a proof of concept of our approach, and demonstrate its feasibility by experiments for arrival routes during one hour at Stockholm TMA.

  • 11.
    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.

  • 12.
    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

  • 13.
    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)
  • 14.
    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.

  • 15.
    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)
  • 16.
    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 Novel MIP-based Airspace Sectorization for TMAs2017Conference paper (Refereed)
  • 17.
    Josefsson, Billy
    et al.
    LFV Research & Innovation, 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 Scheduling2017In: 11th USA/Europe Air Traffic Management Research and Development Seminar 2015: Proceedings, The European Organisation for the Safety of Air Navigation , 2017Conference paper (Refereed)
    Abstract [en]

    —Remote Tower Service (RTSs) is one of the technological and operational solutions delivered for deployment by the Single European Sky ATM Research (SESAR) Programme. 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 (RTM), i.e the controller working position. In this paper, we present an optimization framework for the traffic management at five Swedish airports that were chosen for remote operation using a Remote Tower Center designed to serve a number of airports. We highlight the problems experienced with real airport schedules, and present optimal assignments of the airports to the RTMs. We consider both scheduled traffic and special (non-scheduled) traffic at these five airports.

  • 18.
    Ernestus, Maximilian
    et al.
    TU Braunschweig, Germany.
    Friedrichs, Stephan
    Max Planck Institute Informat, Germany; Saarbrucken Grad School Comp Science, Germany.
    Hemmer, Michael
    TU Braunschweig, Germany.
    Kokemueller, Jan
    TU Braunschweig, Germany.
    Kroeller, Alexander
    TU Braunschweig, Germany.
    Moeini, Mahdi
    Technical University of Kaiserslautern, Germany.
    Schmidt, Christiane
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Algorithms for art gallery illumination2017In: Journal of Global Optimization, ISSN 0925-5001, E-ISSN 1573-2916, Vol. 68, no 1, p. 23-45Article in journal (Refereed)
    Abstract [en]

    The art gallery problem (AGP) is one of the classical problems in computational geometry. It asks for the minimum number of guards required to achieve visibility coverage of a given polygon. The AGP is well-known to be NP-hard even in restricted cases. In this paper, we consider the AGP with fading (AGPF): A polygonal region is to be illuminated with light sources such that every point is illuminated with at least a global threshold, light intensity decreases over distance, and we seek to minimize the total energy consumption. Choosing fading exponents of zero, one, and two are equivalent to the AGP, laser scanner applications, and natural light, respectively. We present complexity results as well as a negative solvability result. Still, we propose two practical algorithms for AGPF with fixed light positions (e.g. vertex guards) independent of the fading exponent, which we demonstrate to work well in practice. One is based on a discrete approximation, the other on non-linear programming by means of simplex-partitioning strategies. The former approach yields a fully polynomial-time approximation scheme for the AGPF with fixed light positions. The latter approach obtains better results in our experimental evaluation.

  • 19.
    Fekete, Sándor P.
    et al.
    Department of Computer Science, TU Braunschweig, Braunschweig, Germany.
    Haas, Andreas
    Department of Computer Science, TU Braunschweig, Braunschweig, Germany.
    Hemmer, Michael
    Department of Computer Science, TU Braunschweig, Braunschweig, Germany.
    Hoffmann, Michael
    Department of Computer Science, ETH Zürich, Zürich, Switzerland.
    Kostitsyna, Irina
    Department of Mathematics and Computer Science, TU Eindhoven, Eindhoven, The Netherlands.
    Krupke, Dominik
    Department of Computer Science, TU Braunschweig, Braunschweig, GermanyDepartment of Computer Science, TU Braunschweig, Braunschweig, Germany.
    Maurer, Florian
    Department of Computer Science, TU Braunschweig, Braunschweig, Germany.
    Mitchell, Joseph S.B.
    Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, NY, USA.
    Schmidt, Arne
    Department of Computer Science, TU Braunschweig, Braunschweig, Germany.
    Schmidt, Christiane
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Troegel, Julian
    Department of Computer Science, TU Braunschweig, Braunschweig, Germany.
    Computing Nonsimple Polygons of Minimum Perimeter2017In: Journal of Computational Geometry (JoCG), ISSN 1920-180X, Vol. 8, no 1Article in journal (Refereed)
    Abstract [en]

    We consider the Minimum Perimeter Polygon Problem (MP3): for a given set V of points in the plane, find a polygon P with holes that has vertex set V , such that the total boundary length is smallest possible. The MP3 can be considered a natural geometric generalization of the Traveling Salesman Problem (TSP), which asks for a simple polygon with minimum perimeter. Just like the TSP, the MP3 occurs naturally in the context of curve reconstruction. Even though the closely related problem of finding a minimum cycle cover is polynomially solvable by matching techniques, we prove how the topological structure of a polygon leads to NP-hardness of the MP3. On the positive side, we provide constant-factor approximation algorithms. In addition to algorithms with theoretical worst-case guarantess, we provide practical methods for computing provably optimal solutions for relatively large instances, based on integer programming. An additional difficulty compared to the TSP is the fact that only a subset of subtour constraints is valid, depending not on combinatorics, but on geometry. We overcome this difficulty by establishing and exploiting geometric properties. This allows us to reliably solve a wide range of benchmark instances with up to 600 vertices within reasonable time on a standard machine. We also show that restricting the set of connections between points to edges of the Delaunay triangulation yields results that are on average within 0.5% of the optimum for large classes of benchmark instances. 

  • 20.
    Schmidt, Christiane
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Andersson Granberg, Tobias
    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.
    CONVEX SECTORIZATION-A NOVEL INTEGER PROGRAMMING APPROACH2017In: 2017 INTEGRATED COMMUNICATIONS, NAVIGATION AND SURVEILLANCE CONFERENCE (ICNS), IEEE , 2017Conference paper (Other academic)
    Abstract [en]

    We present a MIP-based airspace sectorization framework for Terminal Maneuvering Areas that can enforce convex sectors. The approach integrates an airspace complexity representation, and the resulting sectorizations have a balanced taskload. We present results for Stockholm TMA; and compare our results to convex sectorizations obtained by enumerating all possible topologies for a given number of sectors.

  • 21.
    Schmidt, Christiane
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Andersson Granberg, Tobias
    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.
    Convex Sectorization--a Novel Integer Programming Approach2017In: 2017 INTEGRATED COMMUNICATIONS, NAVIGATION AND SURVEILLANCE CONFERENCE (ICNS), IEEE, 2017Conference paper (Refereed)
    Abstract [en]

    The powerpoint presentation is about review of sectorization method that balances sector task load through extension by convex sectors, the results for Stockholm TMA. Also provides the comparison to convex sectorizations obtained by enumerating all possible topoligies for the given #sectors with highly flexible approach and fine-grained view on the TMA.

  • 22.
    Josefsson, Billy
    et al.
    LFV Research & Innovation, Stockholm, 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.
    Scheduling Air Traffic Controllers at the Remote Tower Center2017In: Digital Avionics Systems Conference (DASC), 2017 IEEE/AIAA 36th, IEEE, 2017Conference paper (Refereed)
    Abstract [en]

    Remote Tower Service (RTS) is one of the technological and operational solutions delivered for deployment by the Single European Sky ATM Research (SESAR) Programme. 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” at the Remote Tower Center (RTC), which means that he/she can handle two or more airports from one Remote Tower Module (controller working position). In this paper, we present an optimization framework designed for automation of staff planning at the RTC. We highlight the problems experienced with real airport flight schedules, and present optimal shift assignments for five Swedish airports that were chosen for remote operation.

  • 23.
    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)
  • 24.
    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.
    Automatic Design of Aircraft Arrival Routes with Limited Turning Angle2016In: 16th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2016) / [ed] Marc Goerigk and Renato Werneck, Dagstuhl, Germany, 2016, Vol. 54, p. 9:1-9:13Conference paper (Refereed)
    Abstract [en]

    We present an application of Integer Programming to the design of arrival routes for aircraft in a Terminal Maneuvering Area (TMA). We generate operationally feasible merge trees of curvature-constrained routes, using two optimization criteria: (1) total length of the tree, and (2) distance flown along the tree paths. The output routes guarantee that the overall traffic pattern in the TMA can be monitored by air traffic controllers; in particular, we keep merge points for arriving aircraft well separated, and we exclude conflicts between arriving and departing aircraft. We demonstrate the feasibility of our method by experimenting with arrival routes for a runway at Arlanda airport in the Stockholm TMA. Our approach can easily be extended in several ways, e.g., to ensure that the routes avoid no-fly zones.

  • 25.
    Fekete, Sandor P.
    et al.
    TU Braunschweig, Germany.
    Haas, Andreas
    TU Braunschweig, Germany.
    Hemmer, Michael
    TU Braunschweig, Germany.
    Hoffmann, Michael
    Swiss Federal Institute Technology, Switzerland.
    Kostitsyna, Irina
    TU Eindhoven, Netherlands.
    Krupke, Dominik
    TU Braunschweig, Germany.
    Maurer, Florian
    TU Braunschweig, Germany.
    Mitchell, Joseph S. B.
    SUNY Stony Brook, NY 11794 USA.
    Schmidt, Arne
    TU Braunschweig, Germany.
    Schmidt, Christiane
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Troegel, Julian
    TU Braunschweig, Germany.
    Computing Nonsimple Polygons of Minimum Perimeter2016In: EXPERIMENTAL ALGORITHMS, SEA 2016, SPRINGER INT PUBLISHING AG , 2016, Vol. 9685, p. 134-149Conference paper (Refereed)
    Abstract [en]

    We provide exact and approximation methods for solving a geometric relaxation of the Traveling Salesman Problem (TSP) that occurs in curve reconstruction: for a given set of vertices in the plane, the problem Minimum Perimeter Polygon (MPP) asks for a (not necessarily simply connected) polygon with shortest possible boundary length. Even though the closely related problem of finding a minimum cycle cover is polynomially solvable by matching techniques, we prove how the topological structure of a polygon leads to NP-hardness of the MPP. On the positive side, we show how to achieve a constant-factor approximation. When trying to solve MPP instances to provable optimality by means of integer programming, an additional difficulty compared to the TSP is the fact that only a subset of subtour constraints is valid, depending not on combinatorics, but on geometry. We overcome this difficulty by establishing and exploiting additional geometric properties. This allows us to reliably solve a wide range of benchmark instances with up to 600 vertices within reasonable time on a standard machine. We also show that using a natural geometry-based sparsification yields results that are on average within 0.5% of the optimum.

  • 26.
    Andersson Granberg, Tobias
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Axelsson, Peter
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Petersson, Jonas
    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.
    Configuration and Planning of the Remote TowerModules in a Remote Tower Center2016Conference paper (Refereed)
    Abstract [en]

    Today, many small aerodromes struggle withfinancial difficulties, and a large cost is air traffic control.Remote tower centers, which remotely provide air traffic servicesto aerodromes, can help reduce this cost. Each center maycontain a number of remote tower modules, where each moduleis manned by a controller that can handle one or moreaerodromes. In this paper we present the remote tower centerconcept and develop a model that optimizes the assignment ofairports to the remote tower modules. Computational results fora possible scenario based on real data for Swedish airports arepresented.

  • 27.
    Burke, Kyle
    et al.
    Plymouth State University, NH, USA.
    Demaine, Erik D.
    Massachusetts Institute of Technology, MA, USA.
    Gregg, Harrison
    Bard Coll Simons Rock, MA, USA.
    Hearn, Robert A.
    Portola Valley, CA USA.
    Hesterberg, Adam
    Massachusetts Institute of Technology, MA, USA.
    Hoffmann, Michael
    Swiss Federal Institute Technology, Switzerland.
    Ito, Hiro
    The University of Electro-Communications, Chofu, Japan.
    Kostitsyna, Irina
    University of Iibre Bruxelles, Belgium.
    Leonard, Jody
    Bard Coll Simons Rock, MA, USA.
    Loeffler, Maarten
    University of Utrecht, Netherlands.
    Santiago, Aaron
    Bard Coll Simons Rock, MA, USA.
    Schmidt, Christiane
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering. University of Elect Communicat, Japan.
    Uehara, Ryuhei
    Japan Adv Institute Science and Technology, Japan.
    Uno, Yushi
    Osaka Prefecture University, Japan.
    Williams, Aaron
    Bard Coll Simons Rock, MA, USA.
    Single-Player and Two-Player Buttons & Scissors Games2016In: DISCRETE AND COMPUTATIONAL GEOMETRY AND GRAPHS, JCDCGG 2015 / [ed] Akiyama, J., Ito, H., Sakai, T., Uno, Y., SPRINGER INT PUBLISHING AG , 2016, Vol. 9943, p. 60-72Conference paper (Refereed)
    Abstract [en]

    We study the computational complexity of the Buttons amp; Scissors game and obtain sharp thresholds with respect to several parameters. Specifically we show that the game is NP-complete for C = 2 colors but polytime solvable for C = 1. Similarly the game is NP-complete if every color is used by at most F = 4 buttons but polytime solvable for F amp;lt;= 3. We also consider restrictions on the board size, cut directions, and cut sizes. Finally, we introduce several natural two-player versions of the game and show that they are PSPACE-complete.

  • 28.
    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.

  • 29. 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)
1 - 29 of 29
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