4,781 research outputs found
Prediction of reactionary delay and cost using machine learning
Estimating the potential propagation of delay (and its associated cost) is crucial for the management of the fleet the day of operations. As the flight departure approaches, these estimations need to be as accurate as possible to support pre-tactical and tactical interventions aiming at minimising the network disruption. Dispatcher3 project aims at the use of machine learning models for the prediction and analysis of differences between planned and executed flight plans. Models corresponding to different time-horizons (from departure time to 15 hours before) are developed to predict the flying and turnaround times. These models are combined (with other operational parameters) to estimate reactionary delay and associated expected costs (including potential breaching of curfews). The outcome (delay and costs) is presented as probability distributions. This information could be used to support the flight planning process and the management of the fleet
Increasing project control and guidance efficiency through a time-frame simulation approach
Nowadays projects dynamicity and complexity make the control process highly critical. The existing planning and control techniques have frequently proved inadequacy to manage the present challenge. The paper proposes a simulative approach to managing with more efficiency projects life cycles. The appositely built simulation model is populated with both deterministic and stochastic elements: the formers come from the project plan; the stochastic elements have been introduced in order to consider the probabilistic nature of activities duration. In the planning phase the model generates a “baseline pencil” that gives a more confident estimation of the time to complete the project. During the execution phase the model is able to store the data related to the ongoing activities and updates in real-time the estimation of the project completion. Contemporary, it allows the calculation of specific performance indexes which permit to signal in real-time possible occurring “warnings” to users and suggest potential solutions
The transitional millisecond pulsar IGR J18245-2452 during its 2013 outburst at X-rays and soft gamma-rays
IGR~J18245--2452/PSR J1824--2452I is one of the rare transitional accreting
millisecond X-ray pulsars, showing direct evidence of switches between states
of rotation powered radio pulsations and accretion powered X-ray pulsations,
dubbed transitional pulsars. IGR~J18245--2452 is the only transitional pulsar
so far to have shown a full accretion episode, reaching an X-ray luminosity of
~erg~s permitting its discovery with INTEGRAL in 2013. In
this paper, we report on a detailed analysis of the data collected with the
IBIS/ISGRI and the two JEM-X monitors on-board INTEGRAL at the time of the 2013
outburst. We make use of some complementary data obtained with the instruments
on-board XMM-Newton and Swift in order to perform the averaged broad-band
spectral analysis of the source in the energy range 0.4 -- 250~keV. We have
found that this spectrum is the hardest among the accreting millisecond X-ray
pulsars. We improved the ephemeris, now valid across its full outburst, and
report the detection of pulsed emission up to keV in both the ISGRI
() and Fermi/GBM () bandpass. The alignment of the
ISGRI and Fermi GBM 20 -- 60 keV pulse profiles are consistent at a $\sim25\
\mu$s level. We compared the pulse profiles obtained at soft X-rays with \xmm\
with the soft \gr-ray ones, and derived the pulsed fractions of the fundamental
and first harmonic, as well as the time lag of the fundamental harmonic, up to
s, as a function of energy. We report on a thermonuclear X-ray burst
detected with \Integ, and using the properties of the previously type-I X-ray
burst, we show that all these events are powered primarily by helium ignited at
a depth of g cm. For such a helium
burst the estimated recurrence time of d is in
agreement with the observations.Comment: 10 pages, 6 Figures, 3 Tables Astronomy and Astrophysics Journal,
accepted for publication on the 13th of April 201
Dispatcher3 D7.1 - Project communication, dissemination and exploitation plan
This document is the Communication, Dissemination and Exploitation Plan (D7.1) of the Clean Sky 2 Innovation Action Dispatcher3. The document defines the communication and dissemination actions to be performed during the project, and the potential exploitation of the project results. A complete strategy of communication is presented, as well as the items and content already prepared for it
Dispatcher3 D1.1 - Technical resources and problem definition
This deliverable starts with the proposal of Dispatcher3 and incorporates the development produced during the first five months of the project: activities on different workpackages, interaction with Topic Manager and Project Officer, and input received during the first Advisory Board meeting and follow up
consultations.
This deliverable presents the definition of Dispatcher3 concept and methodology. It includes the high level the requirements of the prototype, preliminary data requirements, preliminary technical infrastructure requirements, preliminary data processing and analytic techniques identification and a preliminary definition of scenarios.
The deliverable aims at defining the view of the consortium on the project at these early stages, incorporating the feedback obtained from the Advisory Board and highlighting the further activities required to define some of the aspects of the project
Spatial distribution of phase singularities in optical random vector waves
We acknowledge funding from ERC Advanced, Investigator Grant (no. 240438-CONSTANS). ADF acknowledges support from EPSRC (EP/L017008/1).Phase singularities are dislocations widely studied in optical fields as well as in other areas of physics. With experiment and theory we show that the vectorial nature of light affects the spatial distribution of phase singularities in random light fields. While in scalar random waves phase singularities exhibit spatial distributions reminiscent of particles in isotropic liquids, in vector fields their distribution for the different vector components becomes anisotropic due to the direct relation between propagation and field direction. By incorporating this relation in the theory for scalar fields by Berry and Dennis, we quantitatively describe our experiments.PostprintPeer reviewe
Pre-Tactical Prediction of Atfm Delay for Individual Flights
The day prior operations, the operation plan is drawn generating a first set of flight plans with the objective of identifying potential network issues and preparing pre-tactical preventing measures. During the day of operation flight plans will be updated and pre-tactical actions implemented if needed by the duty manager, in order to minimise the propagation of disruption in the network. This paper focuses on the estimation of ATFM delay for individual flights during the pre-tactical phase. The main objective is to anticipate which flights might be affected by ATFM regulations and the amount of delay will be assigned to them
A semantic measure of the execution time in linear logic
AbstractWe give a semantic account of the execution time (i.e. the number of cut elimination steps leading to the normal form) of an untyped MELL net. We first prove that: (1) a net is head-normalizable (i.e. normalizable at depth 0) if and only if its interpretation in the multiset based relational semantics is not empty and (2) a net is normalizable if and only if its exhaustive interpretation (a suitable restriction of its interpretation) is not empty. We then give a semantic measure of execution time: we prove that we can compute the number of cut elimination steps leading to a cut free normal form of the net obtained by connecting two cut free nets by means of a cut-link, from the interpretations of the two cut free nets. These results are inspired by similar ones obtained by the first author for the untyped lambda-calculus
A software engine for multi-criteria decision support in flight management - Use of dynamic cost functions - Architecture and first results
Tactical trajectory optimisation should consider the total expected cost of the flight (fuel and delay). The cost of fuel can be estimated from the expected fuel usage. The cost of delay can be approximated by simple non-linear functions but, we propose a methodology to explicitly consider its different components: passenger related (regulation 261, duty of care, missed connections and soft costs), crew and maintenance, and reactionary costs (delay and curfew). This explicit modelling captures the non-continuous aspects of the cost function, which can significantly impact the optimisation profile, e.g. ensure that missed connections are reduced.
The cost of delay, dependent on the arrival time at the gate, can be subject to uncertainties which are inherent (e.g. if a passenger will or not miss a connection) and external (e.g. taxi-in or holding times). Therefore, the optimisation framework should estimate the arrival time to the gate (not the runway) while considering these associated uncertainties.
The described architecture models the processes affecting the cost (e.g. considering probabilities of missed connections or explicit propagation of delay) and operational aspects at arrival which impact the realisation of the planned optimised trajectory (holding time, sequencing and merging distance (tromboning), and taxi-in time). The consideration of the operational uncertainties enables the estimation of the probability of achieving the flight on-time performance.
All these operational uncertainties are integrated into the cost function producing a total expected cost as a function of arrival to FL100 during the descent at the arrival airport.
The trajectory is then optimised in its vertical and speed profile finding the cost index which is expected to minimise the total costs with a simulated annealing framework.
The first results presented describe how the cost functions are generated, uncertainties considered and trajectories optimised for a flight in the LEDM-EDDF route
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