7 research outputs found
Dynamic Flow Management Problems in Air Transportation
In 1995, over six hundred thousand licensed pilots flew nearly thirty-five million flights into over eighteen thousand U.S. airports, logging more than 519 billion passenger miles. Since demand for air travel has increased by more than 50% in the last decade while capacity has stagnated, congestion is a problem of undeniable practical significance. In this thesis, we will develop optimization techniques that reduce the impact of congestion on the national airspace. We start by determining the optimal release times for flights into the airspace and the optimal speed adjustment while airborne taking into account the capacitated airspace. This is called the Air Traffic Flow Management Problem (TFMP). We address the complexity, showing that it is NP-hard. We build an integer programming formulation that is quite strong as some of the proposed inequalities are facet defining for the convex hull of solutions. For practical problems, the solutions of the LP relaxation of the TFMP are very often integral. In essence, we reduce the problem to efficiently solving large scale linear programming problems. Thus, the computation times are reasonably small for large scale, practical problems involving thousands of flights. Next, we address the problem of determining how to reroute aircraft in the airspace system when faced with dynamically changing weather conditions. This is called the Air Traffic Flow Management Rerouting Problem (TFMRP) We present an integrated mathematical programming approach for the TFMRP, which utilizes several methodologies, in order to minimize delay costs. In order to address the high dimensionality, we present an aggregate model, in which we formulate the TFMRP as a multicommodity, integer, dynamic network flow problem with certain side constraints. Using Lagrangian relaxation, we generate aggregate flows that are decomposed into a collection of flight paths using a randomized rounding heuristic. This collection of paths is used in a packing integer programming formulation, the solution of which generates feasible and near-optimal routes for individual flights. The algorithm, termed the Lagrangian Generation Algorithm, is used to solve practical problems in the southwestern portion of United States in which the solutions are within 1% of the corresponding lower bounds
Upravljanje putanjama vazduhoplova u kontroli letenja na pre-taktičkom i taktičkom nivou
Global air traffic demand is continuously increasing, and it is predicted
to be tripled by 2050. The need for increasing air traffic capacity motivates a
shift of ATM towards Trajectory Based Operations (TBOs). This implies the
possibility to design efficient congestion-free aircraft trajectories more in
advance (pre-tactical, strategic level) reducing controller’s workload on tactical
level. As consequence, controllers will be able to manage more flights.
Current flow management practices in air traffic management (ATM)
system shows that under the present system settings there are only timid
demand management actions taken prior to the day of operation such as: slot
allocation and strategic flow rerouting. But the choice of air route for a
particular flight is seen as a commercial decision to be taken by airlines, given
air traffic control constraints. This thesis investigates the potential of robust
trajectory planning (considered as an additional demand management action)
at pre-tactical level as a mean to alleviate the en-route congestion in airspace.
Robust trajectory planning (RTP) involves generation of congestion-free
trajectories with minimum operating cost taking into account uncertainty of
trajectory prediction and unforeseen event. Although planned cost could be
higher than of conventional models, adding robustness to schedules might
reduce cost of disruptions and hopefully lead to reductions in operating cost.
The most of existing trajectory planning models consider finding of conflict-free
trajectories without taking into account uncertainty of trajectory prediction. It is
shown in the thesis that in the case of traffic disturbances, it is better to have a
robust solution otherwise newly generated congestion problems would be hard
and costly to solve.
This thesis introduces a novel approach for route generation (3D
trajectory) based on homotopic feature of continuous functions. It is shown that
this approach is capable of generating a large number of route shapes with a
reasonable number of decision variables. Those shapes are then coupled with
time dimension in order to create trajectories (4D)...Globalna potražnja za vazdušnim saobraćajem u stalnom je porastu i
prognozira se da će broj letova biti utrostručen do 2050 godine. Potreba za
povećanjem kapaciteta sistema vazdušnog saobraćaja motivisala je promene u
sistemu upravljanja saobraćajnim tokovima u kome će u budućnosti centralnu
ulogu imati putanje vazduhoplova tzv. “trajectory-based” koncept. Takav
sistem omogućiće planiranje putanja vazduhoplova koje ne stvaraju zagušenja
u sistemu na pre-taktičkom nivou i time smanjiti radno opterećenje kontrolora
na taktičkom nivou. Kao posledica, kontrolor će moći da upravlja više letova
nego u današnjem sistemu.
Današnja praksa upravljanja saobraćajnim tokovima pokazuje da se mali
broj upravljačkih akcija primenjuje pre dana obavljanja letova npr.: alokacija
slotova poletanja i strateško upravljanje saobraćajnim tokovima. Međutim izbor
putanje kojom će se odviti let posmatra se kao komercijalna odluka aviokompanije
(uz poštovanje postavljenih ograničenja od strane kontrole letenja) i
stoga je ostavljen na izbor avio-kompaniji. Većina, do danas razvijenih, modela
upravljanja putanjama vazduhoplova ima za cilj generisanje bez-konfliktnih
putanja, ne uzimajući u obzir neizvesnost u poziciji vazduhoplova. U ovoj
doktorskoj disertaciji ispitivano je planiranje robustnih putanja vazduhoplova
(RTP) na pre-taktičkom nivou kao sredstvo ublažavanja zagušenja u
vazdušnom prostoru . Robustno upravljanje putanjama vazduhoplova
podrazumeva izbor putanja vazduhoplova sa minimalnim operativnim
troškovima koje ne izazivaju zagušenja u vazdušnom prostoru u uslovima
neizvesnosti buduđe pozicije vazduhoplova i nepredviđenih događaja. Iako
predviđeni (planirani) operativni troškovi robustnih putanja mogu u startu biti
veći od operativnih troškova bez-konfliktnih putanja, robusnost može uticati na
smanjenje troškove poremećaja putanja jer ne zahteva dodatnu promenu
putanja vazduhplova radi izbegavanja konfliktnih situacija na taktičkom nivou.
To na kraju može dovesti i do smanjenja stvarnih operativnih troškova. U tezi je
pokazano, da je u slučaju poremećaja saobraćaja bolje imati robustno rešenje
(putanje), jer novo-nastali problem zagušenosti vazdušnog prostora je teško i
skupo rešiti..
The application of operational research to European air traffic flow management Understanding the context
SIGLEAvailable from British Library Document Supply Centre-DSC:9261.954(WBS-RB-RP--200) / BLDSC - British Library Document Supply CentreGBUnited Kingdo
The application of operational research to European air traffic flow management - understanding the context
This paper is aimed at laying the groundwork for the application of operational research to European air traffic flow management (ATFM). It is based on a project carried out at the EUROCONTROL Central Flow Management Unit (CFMU), the organisation that manages traffic flows in the 36 states belonging to the European Civil Aviation Conference. The paper describes the making of the CFMU, its organisation and systems, the different measures, levels of planning and stakeholders in ATFM and how flow managers carry out their work. In so doing the paper identifies potential applications of operational research to European ATFM, and describes a re-routing demonstrator developed to illustrate different decision support possibilities for re-routing measures. (C) 2000 Elsevier Science B.V. All rights reserved