Automatic Conflict Solving using Biharmonic Navigation Functions

International audience; Automatic conflict solving is an old standing problem within the field of ATM. Proposed algorithms fall into two categories : - Deterministic ones that have a provable property of collision avoidance. For all known algorithms, trajectories produced are generally not flyable because no bounds on speed and curvature can be imposed. - Stochastic methods that select an optimal sequence of manoeuvres. By design, trajectories are flyable, but no guarantee can be given on the fact that a collision-free planning can be found in finite time. It is highly desirable for a wide social acceptance of automated trajectory planning, even at a strategical level, that the algorithms in use have by-design the collision avoidance property and, at the same time, a mean of keeping the speed within a given interval. Navigation functions are common in the field of robotics but do not have the last property. We present a new approach based on biharmonic functions yielding a navigation field with constant speed. Such functions have been considered previously, but proof of collision avoidance is lacking: we address this problem in this work as summarized below. Navigation functions produce a speed field by taking the gradient of a potential function: if the obstacles to be avoided are at a higher potential than inner points of the domain (including destination), collision avoidance is guaranteed. If the potential has the Morse property (no critical point is degenerated) then there exists a descent direction at every point of the admissible domain, making the destination reachable. In the framework of biharmonic functions, a tensor field is produced instead of a vector one ; the Morse property is no longer relevant. We show here that all benefits of navigation functions can be recovered through the use of the bienergy density, with the ability to get constant speed fields. Document type: Conference objec

Planification de trajectoires d'avions sans conflit : fonctions biharmoniques et fonction de navigation harmonique

Nous nous plaçons ici dans le cadre d'une planification de trajectoires d'avion dans des secteurs free-route, c'est-à-dire des secteurs où les avions ne sont plus astreints à suivre les routes aériennes. Cette planification est réalisée plusieurs jours, voir semaines avant le décollage. Notre but n'est pas de contrôler les avions en temps réel afin de garantir l'évitement de conflit, mais d'organiser le trafic en amont afin que les seuls conflits que les contrôleurs aient à gérer soient liés à des perturbations du système (comme les aléas météorologiques). Un tel outil de planification pourrait également être utilisé comme outil de simulation, afin par exemple de prendre des décisions sur l'allocation de créneaux de décollage. Cette thèse s'intéresse à l'utilisation de la méthode des champs de potentiel pour la planification de trajectoires sans conflits d'un grand nombre d'avions. L'étude des champs de potentiel harmoniques, ainsi que des champs biharmoniques montrent les limites de ces méthodes qui explosent en temps de calcul lorsque le nombre d'avions augmente. Cette conclusion nous a poussé à étudier un autre type de champs de potentiel : les fonctions de navigation, déjà utilisées pour la résolution de conflits aériens. Nous proposons dans la dernière partie de cette thèse une nouvelle fonction de navigation, qui s'inspire à la fois des travaux réalisés sur les champs de potentiel harmoniques et sur les fonctions de navigation. Cette fonction de navigation harmonique permet de planifier un très grand nombre de trajectoires en un temps très court, tout en garantissant théoriquement certaines propriétés intéressantes pour les trajectoires obtenues, comme une vitesse constante par exemple. Des pistes d'amélioration de la fonction de navigation harmonique sont également proposées, notamment pour optimiser les trajectoires obtenues lors de la planification.We consider a planning of aircraft trajectories in free-route sectors, i.e. sectors where aircraft do not have to follow air routes anymore. The planning is done several days, or even weeks before take-off. Our goal does not entail control of the aircraft in real time to avoid conflicts, but an organization of the traffic so the only conflicts the controllers have to manage come from perturbations of the system (like meteorological hazard). Such a planning tool could also be used as a simulation tool, to determine for example take-off planning. This thesis focuses on the potential fields method to plan conflict-free trajectories for a large number of aircraft. The study of harmonic potential fields, as well as biharmonic fields highlights the limits of these methods: their computation time explodes with the increase of the number of flights. This conclusion brought us to study an other type of potential fields: the navigation functions, already used for conflict-avoidance. We propose in the last part of this thesis a new navigation function, based on previous work on harmonic functions and navigation functions. This harmonic navigation function is able to plan a large number of aircraft trajectories with a very small computation time. It also guarantees some good properties for the planned trajectories, like constant speed. Some leads are also given on how to improve the harmonic navigation function, especially how to optimize the trajectories it produces

Génération automatique de trajectoires aériennes sans conflit à l'aide de fonctions biharmoniques

National audienceLe projet SESAR a été mis en place afin de renouveler et d''uniformiser les systèmes de contrôle aérien sur toute l'Europe. Le système actuel de sectorisation de l'espace aérien ayant atteint ses limites, de nouvelles techniques de planification de trajectoires et d'aide à la décision doivent être mises en place afin d'aider les contrôleurs dans leur travail. Une des pistes envisagées consiste à contraindre un avion en position et en temps, ce qui permettrait de garantir l'évitement de conflit ainsi que l'heure d'arrivée de l'avion, réduisant ainsi de manière significative le nombre d'interventions nécessaires de la part des contrôleurs et permettant l'augmentation du trafic

Congenital lung malformations: correlation between prenatal and postnatal imaging and pathological findings

Aim: Congenital lung malformations are a common finding during prenatal ultrasonography (US). Investigations were completed by means of prenatal MRI and postnatal computed tomographic (CT) scan. The purpose of this study was to compare these prenatal findings with postnatal findings and pathological findings after surgical resection.Materials and methods: Prenatal examinations and postnatal CTscan results of congenital malformations were compared with pathological findings.Results: From 2007 to 2013, 39 prenatally diagnosed congenital lung malformations were resected: 18 congenital cystic adenomatoid malformation, eight pulmonary sequestration, five bronchogenic cyst, one bronchial atresia and six complex lesions. Correlation between imaging and diagnosis was as follows: congenital cystic adenomatoid malformation was seen in 17/17 patients using postnatal CT, in 10/15 patients using prenatal MRI and in 17/18 patients using prenatal US. Correlation between imaging and diagnosis was as follows: bronchogenic cyst was seen in 3/5, 3/5 and 3/5 patients, pulmonary sequestration was seen in 7/9, 5/9 and 4/9 patients, and complex lesion was seen in 4/5, 3/6, and 2/6 patients using postnatal CT, prenatal MRI, and prenatal US,  respectively. Overall, 32/37 cases were diagnosed by means of postnatal CT, 21/36 cases were diagnosed by means of prenatal MRI and 26/39 cases were diagnosed by means of prenatal US.Conclusion: Discordance between imaging data and definitive diagnosis is not rare. Our results suggest that postnatal CT scan is the most sensible and specific examination. Before birth, US seems better compared with MRI for description of the lesion. MRI seems to be useful in case of complex lesions and pulmonary sequestration.Keywords: congenital lung malformation, imaging, prenata

Gender, risk and the Wall Street alpha male

From the outset, analyses of the 2008 financial crisis, in mainstream as well as feminist discussions, have been gendered. In particular, rampant risk taking in an unregulated environment, widely deemed to be a principle cause of the crash, has been associated with masculine characteristics. In this article I explore how the concepts of gender and risk entwine in two films on the financial crisis – The Other Guys and Margin Call. By looking at how gender is used to dramatise financial risk, I explore how understandings of high risk behaviour are gendered, and the implications this has in the context of finance. Fictional representations mediate public understanding of this notoriously complex field, as the number of films and documentaries on the crisis demonstrates. Exploring how gender is used to communicate risk reminds us that risk taking is part of a performance of masculinity that needs to be established by constructing a feminine, risk-averse other. The contention of this paper is that to address gender bias in finance and the economy, gendered meanings of risk need to be openly challenged, and cultural and material analyses of gendered inequality brought into dialogue

Advances in the role of sacral nerve neuromodulation in lower urinary tract symptoms

Sacral neuromodulation has been developed to treat chronic lower urinary tract symptoms, resistant to classical conservative therapy. The suspected mechanisms of action include afferent stimulation of the central nervous system and modulation of activity at the level of the brain. Typical neuromodulation is indicated both in overactivity and in underactivity of the lower urinary tract. In the majority of patients, a unilateral electrode in a sacral foramen and connected to a pulse generator is sufficient to achieve significant clinical results also on long term. In recent years, other urological indications have been explored

Gran Ballet de Montecarlo

Direcció artística Napoleone AnnovazziEl lago de los cisnes, amb música de Tchaikowsky, coreografia de Marius Petipa i Leo Ivanoff i decorats d'Eugène Dunkel; Paso a Cuatro, ballet amb música de Cesare Pugni, coreografia d'Anton Dolin i vestuari d'Irene Karinska inspirat en una imatge de l'època d'Alfred Edward Chalon; Una tragedia en Verona, ballet amb música de Txaikovski, coreografia de George Skibine i decorats i vestuari realitzats per André Delfau executats per Irene Karinska; El bello Danubio, amb música de Johann Strauss arranjada i instrumentada per Roger Désormière, amb coreografia de Leonide Massine i decorats i vestuari de Constantin GuysEmpresa: José F. ArquerOrquesta Sinfónica del Gran Teatro del Liceo ; directors Gustave Cloez i Charles BoisardDe cada obra s'ha digitalitzat un programa sencer. De la resta s'han digitalitzat les parts que són diferents

Gran Ballet de Montecarlo

Concerto Barrocco, amb la música del concert en re menor per a dos violins de Johann Sebastian Bach i coreografia de George Balanchine; Una tragedia en Verona, ballet amb música de Txaikovski, coreografia de George Skibine i decorats i vestuari realitzats per André Delfau executats per Irene Karinska; Paso a Cuatro, ballet amb música de Cesare Pugni, coreografia d'Anton Dolin i vestuari d'Irene Karinska inspirat en una imatge de l'època d'Alfred Edward Chalon; El bello Danubio, amb música de Johann Strauss arranjada i instrumentada per Roger Désormière, amb coreografia de Leonide Massine i decorats i vestuari de Constantin GuysDirecció artística Napoleone AnnovazziEmpresa: José F. ArquerOrquesta Sinfónica del Gran Teatro del Liceo ; directors Gustave Cloez i Charles BoisardDe cada obra s'ha digitalitzat un programa sencer. De la resta s'han digitalitzat les parts que són diferents

Distribution and Cconnection to other Plant-Communities of Genista radiata (L.) Scop in the South Tyrol (Italy)

Es werden die Genista radiata-Bestände an der Mendel in Südtirol (Italien) beschrieben und ihr Gesellschaftsanschluß diskutiert. Das Genisto-Festucetum alpestris Peer 83 besidelt steile südexponierte Kalkhänge der hochmontanen und subalpinen Stufe und ersetzt z.T. den Zwergstrauchgürtel mit Pinus mugo. Ähnlich zusammengesetzt ist das Genisto-Festucetum alpestris pinetosum Peer 83, das in den ¡lockeren Erika-Kiefernwäldern auftritt und bis in die tiefmontane Stufe hinunterreicht. Keinerlei syntaxonomische Bedeutung besitzt Genista radiata in den thermophilen Buschwaldgesellschaften, in denen die Pflanze lediglich eine Variante zum Orno-Ostryetum seslerietosum Peer 81 darstellt und speziell in der Saumzone anzutreffen ist. Auch in den Lärchenwiesen der Kammlagen kommt Genista radiata nur sporadisch vor. Sie ist hier mit dem Festucetum nigrescentis laricetosum subass. prov. verzahnt.Istražene su vegetacijske sastojine vrste Genista radiata u južnom Tirolu i razmatrana njihova fitocenološka pripadnost. Asocijacija Genisto-Festucetum alpestris Peer 83 nastava strme, južne vapnenačke obronke visokobrdskog i subalpskog pojasa. Subasocijacija Genisto-Festucetum alpestris pinetosum Peer 83 dolazi u rijetkim borovim šumama s crnjušom i spušta se do u niži brdski pojas. Termofilne niske šume, u kojima Genista radiata nema posebno sintaksonomsko značenje, označene su samo kao varijanta zajednice Orno-Ostryetum seslerietosum Peer 81. Genista radiata dolazi također na travnjacima s arišem, ali samo sporadično i to u mješavini sa zajednicom Festucetum nigrescentis laricetosnm subass. prov.The Genista radiata-communities of the Mendel in the South Tyrol (Italy) are described and their connection to other plant-communities is discussed. Genisto-Festucetum alpestris Peer 83 settles on steep, south- exposed colcareous slopes of high-mountain and subalpine altitudes and replaces particularly the dwarf-shrub-belt with Firms mugo. Similar contents aire found in Genisto-F estucetum alpestris pinetasum Peer 83, which occurs in undensed Erico-Pinetum-communities and reaches down to the low-mountain-altitude. In the thermophilic bush-communities, in which Genista radiata is found only as a variant of Orneto-Ostryetum seslerie- tosum (Peer 81), the plant has no syntaxonomic importance. Genista radiata especially is found in the edge-zone. In the grassland of the larch- communities of the ridges Genista radiata appears only sporadically. Here the plant appeals in Festucetum nigrescentis laricetosum subass. prov