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Rationale for a New Transport Protocol in the Aeronautical Telecommunication Network
No full textInternational audienceThis research work identifies the reliability needs for aeronautical telecommunication network (ATN) applications taking into account the performance metrics imposed by the standards of the International Civil Aviation Organization (ICAO), typically the Required Communication Performance (RCP) documents. The study is based on the existing OSI protocol stack simulations using OMNET++ software. The data traffic generated by each node is based on a statistical analysis of real Controller-Pilot DataLink Communications (CPDLC) log files obtained from French Area Control Center (ACC). The simulation results highlight the limits of the OSI protocols in particular at the level of the transport layer with the Connection-Oriented Transport Protocol Class 4 (COTP4) compared to TCP New Reno version that we considered in this study. Moreover, relevant analysis of these limits allows us to define the end-to-end reliability properties and mechanisms that the transport layer should provide for the future ATN/IPS networks
Price Competition and Endogenous Product Choice in Networks: Evidence from the US Airline Industry
No full textInternational audienceWe develop a two-stage game in which competing airlines first choose the networks of markets to serve in the first stage before competing in price in the second stage. Spillovers in entry decisions across markets are allowed, which accrue on the demand, marginal cost, and fixed cost sides. We show that the second-stage parameters are point identified, and we design a tractable procedure to set identify the first-stage parameters and to conduct inference. Further, we estimate the model using data from the domestic US airline market and find significant spillovers in entry. In a counterfactual exercise, we evaluate the 2013 merger between American Airlines and US Airways. Our results highlight that spillovers in entry and post-merger network readjustments play an important role in shaping post-merger outcomes
Towards Proved Formal Specification and Verification of STL Operators as Synchronous Observers
No full textInternational audienceSignal Temporal Logic (STL) is a convenient formalism to express bounded horizon properties of autonomous critical systems. STL extends LTL to real-valued signals and associates a non-singleton bound interval to each temporal operators. In this work we provide a rigorous encoding of non-nested discrete-time STL formulas into Lustre synchronous observers. Our encoding provides a three-valued online semantics for the observers and therefore enables both the verification of the property and the search of counterexamples. A key contribution of this work is an instrumented proof of the validity of the implementation. Each node is proved correct with respect to the original STL semantics. All the experiments are automated with the Kind2 modelchecker and the Z3 SMT solver
Quantifying the mixing of trade‐wind cumulus during the NEPHELAE‐EUREC4A field campaign with remotely piloted aircraft
No full textInternational audienceAbstract During the Network for studying Entrainment and microPHysics of cLouds using Adaptive Exploration (NEPHELAE)–ElUcidating the RolE of Cloud–Circulation Coupling in ClimAte (EUREC4A) field campaign in January and February 2020 in Barbados, remotely piloted aircraft (RPA) were implemented to characterise the structures of trade‐wind cumulus for a total of 40 flights. Two observation methods were tested: one making racetracks to get statistics on the cumulus clouds and a new sampling strategy using sensor‐driven adaptive sampling to track an individual cloud autonomously throughout its lifetime. It appears from the statistics that there are two types of cohabiting cloud population, with small‐diameter clouds (transect lengths less than 500 m) being less buoyant than larger clouds (transect lengths greater than 500 m). Also, this statistical study shows that cumulus clouds do not have an adiabatic core. These results are compared with individual clouds tracked by adaptive sampling, which also show that the core of the cumulus clouds is diluted by the environment. A comparison with high‐resolution large‐eddy simulations shows that these numerical studies tend to underestimate mixing in the whole cloud
Dynamic All-Different and Maximal Cliques Constraints for Fixed Job Scheduling
No full textInternational audienceThe resolution of Fixed Job Scheduling (FJS) withConstraint Programming can benefit from the initial computationof the set of all maximal cliques over the task intervals to postAll-Different constraints over the allocation variables. However,when direct successors are assigned during the search, singletasks can be replaced by task chains with a longer duration andpossibly added to some of the original cliques to strengthen themodel.We propose a new global constraint to efficiently maintainall the maximal cliques over the task chains of an FJS problemupon successor assignment, which can be used to add variables toDynamic All-Different constraints posted on the original cliquesinstead of static ones. Experiments on random and real-worldinstances of the Gate Allocation Problem, a classic applicationof FJS, show that our approach can outperform former modelsand state-of-the-art MIP solver by orders of magnitude
Utilisation de simulations aux grandes échelles pourla propagation électromagnétique 2D en milieuxturbulents réalistes
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Spherical Codec for V2X Cooperative Awareness Trajectory Compression: A Preliminary Study
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Collaborative Generation of Local Conflict Free Trajectories With Weather Hazards Avoidance
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Fifteenth USA/Europe Air Traffic Management Research and Development Seminar (ATM2023) STL combining LSTM for long-term predicting airport traffic flow
No full textInternational audienceAirport traffic flow exhibits significant periodicity on a daily scale, few studies have given attention to periodicity when predicting airport traffic flow. In this article, we propose a novel model that combines long short-term memory (LSTM) and seasonal-trend decomposition procedure based on loess (STL) to predict the arrival/departure traffic flow at the airport. A sinusoidal template-matching method based on Fréchet distance is used to restack the periodic input variables. A time series decomposition algorithm STL is used to decompose the traffic flow time series into trend, seasonal, and remainder components to identify its periodic structure. LSTM model is trained using historical airport operation data, strategic flight schedule data, and meteorological data from Beijing Capital International Airport, Guangzhou Baiyun International Airport, and Shanghai Pudong International Airport in 2019. Our results demonstrate that both the adaptive restack of input variables and the time series decomposition algorithm STL can improve the prediction performance. Our proposed method shows superior performance in long-time prediction (720-time steps). In particular, STL combined LSTM method achieves an R-squared of 0.97 and a mean absolute error (MAE) of less than 1.58 for all three airports
Meta-Heuristics Approach for Arrival Sequencing and Delay Absorption through Automated Vectoring
No full textInternational audienceThe continuous increase in air traffic compelsmajor airports to optimize their resources and enhance theirTerminal Maneuvering Airspace (TMA) operations. The pri-mary constraint to increasing airport capacity is the requiredseparation minima between pairs of aircraft arriving throughthe same approach routes. RECAT-EU is a revised global wakeseparation minima scheme released by EUROCONTROL in2018. This suggested a reduction in separation minima betweencertain aircraft pairs while maintaining safety levels. However, itincreases in separation minima scheme complexity by doublingthe number of non-minimum radar separation (MRS) values.In this work, a Meta-Heuristic based optimization model isproposed to sequence arrival flights based on the RECAT-EUseparation scheme, which can provide an optimized vectoringto ensure flights absorb their assigned delays before reachingthe final approach fix. Findings show that the proposed modelis able to generate an optimized landing sequence for 50 arrivalflights in a computation time of 16 seconds. It also suggests thatthe proposed algorithm’s computational time increases linearlywith increasing the number of flights. Furthermore, trajectoryvectoring results demonstrate that 85% of the assigned delayscould be absorbed by flying the proposed vectored trajectories