| 1. |
- Hajizadeh, Roghayeh, 1986-, et al.
(författare)
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A Dantzig-Wolfe Reformulation for AutomatedAircraft Arrival Scheduling in TMAs
- 2024
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Ingår i: Proceedings of the 14th International Conference on the Practice and Theory of Automated Timetabling, PATAT 2024. - 9780992998462 ; , s. 268-271
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Konferensbidrag (refereegranskat)abstract
- In this paper, we introduce a Dantzig-Wolfe reformulation to compute aircraft arrival routes in a terminal maneuvering area (TMA) where the aircraft are flying according to theoptimal continuous-descent-operation (CDO) speed profile with idle thrust. This model assumes fixed entry times for all aircraft and a single separation time that is independent of wake-turbulence categories.Preliminary experiments show that this approach leads to significantly reduced runtimes.Moreover, the results indicate the possiblity of extending the reformulation to the full model and applying it to address additional practical considerations, such as wind effects in the future.
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| 2. |
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| 3. |
- Aichholzer, Oswin, et al.
(författare)
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Folding Polyominoes with Holes into a Cube
- 2021
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Ingår i: Computational geometry. - : Elsevier. - 0925-7721 .- 1879-081X. ; 93
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Tidskriftsartikel (refereegranskat)abstract
- When can a polyomino piece of paper be folded into a unit cube? Prior work studied tree-like polyominoes, but polyominoes with holes remain an intriguing open problem. We present sufficient conditions for a polyomino with one or several holes to fold into a cube, and conditions under which cube folding is impossible. In particular, we show that all but five special “basic” holes guarantee foldability.
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| 6. |
- Andersson Granberg, Tobias, 1973-, et al.
(författare)
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Integer Programming-Based Airspace Sectorization for Terminal Maneuvering Areas with Convex Sectors
- 2019
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Ingår i: Journal of Air Transportation. - : American Institute of Aeronautics and Astronautics. - 2380-9450. ; 27:4
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 7. |
- Daescu, Ovidiu, et al.
(författare)
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Altitude Terrain Guarding and Guarding Uni-Monotone Polygons
- 2019
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Ingår i: Computational geometry. - : Elsevier. - 0925-7721 .- 1879-081X. ; 84, s. 22-35
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 9. |
- Friedrichs, Stephan, et al.
(författare)
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The continuous 1.5D terrain guarding problem: Discretization, optimal solutions, and PTAS
- 2016
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Ingår i: Journal of Computational Geometry. - : Carleton University. - 1920-180X. ; 7:1, s. 256-284
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 10. |
- Josefsson, Billy, et al.
(författare)
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A Step Towards Remote Tower Center Deployment: Optimizing Staff Scheduling
- 2019
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Ingår i: Journal of Air Transportation. - : American Institute of Aeronautics and Astronautics. - 2380-9450. ; 27:3
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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