Wind and Temperature Networking Applied to Aircraft Trajectory Prediction

International audienceTrajectory prediction estimates the future position of aircraft along their planned trajectories in order to detect potential conflicts and to optimize air space occupancy. This prediction is a critical task in the Air Traffic Control (ATC) process and has been studied for many years. For the future automation processes developed in the SESAR [19], NextGen [15] and CARATS [3] projects, such trajectory prediction will be even more critical. As there is always a deviation between the predicted wind (from the weather forecasts) and the encountered wind, the main longitudinal (along-track) error source between the predicted and the actual trajectory is linked to wind estimation. Even if the main longitudinal (along-track) error source between the predicted and the actual trajectory is linked to wind estimation, temperature wrong estimation may also lead to ETE1 prediction errors. In a previous paper [11] we measured the potential benefit produced by sharing wind measures between aircraft. In the present paper we will try to improve the trajectory prediction by sharing the wind and the temperature information between aircraft. Addressing the temperature came when we noticed that at least the cruising phase of many flight was performed at constant Mach number. Maintaining a given Mach number under changing temperatures equals changing the true air speed. Based on the current performances of Air Traffic Control systems , controllers are able to efficiently detect conflict 20 minutes in advance ; for a larger time horizon (look-ahead time), the induced trajectory prediction uncertainty strongly reduces the reliability of the conflict detection. The goal of this work is to measure the potential benefit produced by sharing wind/temperature measures between aircraft (this concept will be called Wind/Temp Networking (WTN)). To reach this goal, aircraft measure (temperature and pressure) and calculate (wind and density) their local atmospheric data and broadcast them to the other aircraft. Having such distributed weather information, each aircraft is able to compute an enhanced local wind/temperature map as a function of location (3D) and time. These updated wind/temp fields could be shared with other aircraft and/or with ground systems. Using this enhanced weather information, each aircraft is able to improve drastically its own trajectory prediction. This concept has been simulated in the French airspace with 8 000 flights. Comparisons have been investigated on trajectory prediction performances with and without wind/temp networking. Statistics have been conducted in order to measure the benefit of such concept in both time and space dimensions showing higher improvement in high traffic areas, as expected

Optimisation du trafic aérien en tenant compte des conditions météorologiques

National audienceDans le cadre des systèmes de gestion du trafic aérien du futur, nous nous intéressons ici au concept "Free Flight" dans lequel les avions ne sont plus astreints à suivre des trajectoires définies par des routes aériennes et pourraient ainsi rechercher des trajectoires optimisées relativement à un critère de coût. Dans les travaux présentés ici, le choix s'est porté sur la minimisation du temps de vol en exploitant les conditions météorologiques, tout en minimisant la congestion engendrée par l'ensemble des vols.La méthodologie mise en œuvre se déroule en deux étapes. La première consiste à calculer la trajectoire optimale en temps de vol de manière indépendante pour chaque avion. Cette planification est effectuée à l'aide d'un algorithme basé sur la méthode Ordered Upwind. A partir de ces trajectoires, nous calculons une métrique de congestion simple pour nous permettre d'évaluer la complexité du trafic. La métrique choisie ici correspond au nombre d'avions présents dans un voisinage défini à un temps donné.La deuxième étape a pour but de modifier les trajectoires initiales afin de minimiser la congestion globale du trafic. Pour cela, un algorithme de Recuit Simulé est appliqué de la façon suivante. A chaque itération, une trajectoire est tirée aléatoirement. Elle est recalculée, à l'aide de l'algorithme de la première étape, en pénalisant les zones congestionnées pour obtenir la trajectoire optimisée pour le critère pénalisé. Nous réévaluons ensuite la complexité du trafic avec cette nouvelle trajectoire.L'adaptation de l'algorithme Ordered Upwind sur la sphère, nous a permis de travailler avec des données réelles de vent et de trafic sur un espace aérien à l'échelle européenne

Wind-Optimal Path Planning: Application to Aircraft Trajectories

International audienceIn this paper, an algorithm to plan a continuous wind-optimal path is proposed, and simulations are made for aircraft trajectories. We consider a mobile which can move in a two dimensional space. The mobile is controlled only by the heading direction, the speed of the mobile is assumed to be constant. The objective is to plan the optimal path avoiding obstacles and taking into account wind currents. The algorithm is based on Ordered Upwind Method which gives an optimality proof for the solution. The algorithm is then extended to spherical coordinates in order to be able to handle long paths

Aircraft trajectory forecasting using local functional regression in Sobolev space

International audienceThis paper considers the problem of short to mid-term aircraft trajectory prediction, that is, the estimation of where an aircraft will be located over a 10-30 min time horizon. Such a problem is central in decision support tools, especially in conflict detection and resolution algorithms. It also appears when an air traffic controller observes traffic on the radar screen and tries to identify convergent aircraft, which may be in conflict in the near future. An innovative approach for aircraft trajectory prediction is presented in this paper. This approach is based on local linear functional regression that considers data preprocessing, localizing and solving linear regression using wavelet decomposition. This algorithm takes into account only past radar tracks, and does not use any physical or aeronautical parameters. This approach has been successfully applied to aircraft trajectories between several airports on the data set that is one year air traffic over France. The method is intrinsic and independent from airspace structure

Generating optimal aircraft trajectories with respect to weather conditions

International audienceTwo major projects have been initiated to improve air traffic management by enabling 4D trajectory planning, whereby the aircraft plan their trajectory both in position and in time. In this paper, we are interested in a Free Flight variant of the concept, whereby airspace users are allowed maximum freedom when selecting routes: aircraft are no longer restricted to fly along airways; rather, they are allowed to fly along optimal routes, from origin to destination, following optimal altitudes, using favourable winds and avoiding hazards. Such optimal routes are good for the environment, for the airlines, and for passengers. The goal of our research is to generate trajectories which minimize congestion and travel time of each aircraft in a way that is fair and efficient. We first optimize the route of a single aircraft relying on an algorithm called Ordered Upwind. And then, with a multi-agent system, we modify trajectories in order to minimize the congestion and to stay as close as possible to the optimal trajectories

Le projet ACTIFS face à l’altérité des étudiants et des établissements

La méthode « Peer instruction » (Mazur 1997) consiste à poser des questions à l’auditoire, qui répond à l’aide d’un dispositif de vote. En fonction du taux de bonnes réponses, l’enseignant invite les étudiants à argumenter leur réponse avec leurs voisins, puis à voter à nouveau avant de commenter les résultats. Le projet ACTIFS vise à développer cette méthode sur l’ensemble des 15 formations d’ingénieurs de Midi-Pyrénées, et a touché environ 120 enseignants, 7000 étudiants. La diversité de cet environnement est donc conséquente et a été largement prise en compte dans ce projet. Nous examinons dans cette étude le type et l’impact des altérités impliquées par ce projet et nous présentons un premier bilan en termes de ressenti par les étudiants et les enseignants

Conjunctival Inflammatory Gene Expression Profiling in Dry Eye Disease: Correlations With HLA-DRA and HLA-DRB1

Purpose: In several multicenter clinical trials, HLA-DR was found to be a potential biomarker of dry eye disease (DED)'s severity and prognosis. Given the fact that HLA-DR receptor is a heterodimer consisting in an alpha and a beta chain, we intended to investigate the correlation of inflammatory targets with the corresponding transcripts, HLA-DRA and HLA-DRB1, to characterize specific targets closely related to HLA-DR expressed in conjunctival cells from patients suffering from DED of various etiologies.Methods: A prospective study was conducted in 88 patients with different forms of DED. Ocular symptom scores, ocular-staining grades, tear breakup time (TBUT) and Schirmer test were evaluated. Superficial conjunctival cells were collected by impression cytology and total RNAs were extracted for analyses using the new NanoString® nCounter technology based on an inflammatory human code set containing 249 inflammatory genes.Results: Two hundred transcripts were reliably detected in conjunctival specimens at various levels ranging from 1 to 222,546 RNA copies. Overall, from the 88 samples, 21 target genes showed a highly significant correlation (R > 0.8) with HLA-DRA and HLA-DRB1, HLA-DRA and B1 presenting the highest correlation (R = 0.9). These selected targets belonged to eight family groups, namely interferon and interferon-stimulated genes, tumor necrosis factor superfamily and related factors, Toll-like receptors and related factors, complement system factors, chemokines/cytokines, the RIPK enzyme family, and transduction signals such as the STAT and MAPK families.Conclusions: We have identified a profile of 21 transcripts correlated with HLA-DR expression, suggesting closely regulated signaling pathways and possible direct or indirect interactions between them. The NanoString® nCounter technology in conjunctival imprints could constitute a reliable tool in the future for wider screening of inflammatory biomarkers in DED, usable in very small samples. Broader combinations of biomarkers associated with HLA-DR could be analyzed to develop new diagnostic approaches, identify tighter pathophysiological gene signatures and personalize DED therapies more efficiently

L-Ilf3 and L-NF90 Traffic to the Nucleolus Granular Component: Alternatively-Spliced Exon 3 Encodes a Nucleolar Localization Motif

Ilf3 and NF90, two proteins containing double-stranded RNA-binding domains, are generated by alternative splicing and involved in several functions. Their heterogeneity results from posttranscriptional and posttranslational modifications. Alternative splicing of exon 3, coding for a 13 aa N-terminal motif, generates for each protein a long and short isoforms. Subcellular fractionation and localization of recombinant proteins showed that this motif acts as a nucleolar localization signal. Deletion and substitution mutants identified four arginines, essential for nucleolar targeting, and three histidines to stabilize the proteins within the nucleolus. The short isoforms are never found in the nucleoli, whereas the long isoforms are present in the nucleoplasm and the nucleoli. For Ilf3, only the posttranslationally-unmodified long isoform is nucleolar, suggesting that this nucleolar targeting is abrogated by posttranslational modifications. Confocal microscopy and FRAP experiments have shown that the long Ilf3 isoform localizes to the granular component of the nucleolus, and that L-Ilf3 and L-NF90 exchange rapidly between nucleoli. The presence of this 13 aminoacid motif, combined with posttranslational modifications, is responsible for the differences in Ilf3 and NF90 isoforms subcellular localizations. The protein polymorphism of Ilf3/NF90 and the various subcellular localizations of their isoforms may partially explain the various functions previously reported for these proteins

Extension des méthodes de modélisation auto-adaptatives et du filtrage de Kalman-Bucy : Application à la commande numérique d'un réacteur d'épitaxie

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Faire parler les étudiants : Pourquoi ? Comment ?: "PEG" : Progresser En Groupe Une Pédagogie basée sur l'Entraide au sein d'un Groupe

International audienceQuelle que soit la matière enseignée, il est indispensable, pour que les étudiants progressent et mémorisent leurs progrès, de leur donner l'occasion de parler, car on construit son savoir à travers une confrontation, non seulement avec soi-même mais aussi avec ses semblables. Il s'agit donc de trouver diverses méthodes pour faire parler les étudiants sur les sujets que nous désirons qu'ils acquièrent. "PEG" ("Progresser En Groupe") est une méthode globale et cohérente, basée sur le travail en groupes de quatre étudiants, qui oblige les étudiants à discuter, échanger leurs points de vue, leurs difficultés et à chercher à les résoudre ensemble, depuis la motivation (par un "problème de positionnement-motivation" donné en tout début d'enseignement), jusqu'à la mise en oeuvre par des travaux pratiques, en passant par le travail du cours et des exercices d'assimilation et de développement. L'enseignant intervient aux moments propices, soit en répondant aux questions des groupes, soit par des "cours de restructuration"