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Redesigning systems for Single-Pilot Operations: the mutual awareness problem for remote crews
No full textInternational audienceCurrently, fight safety is ensured by the collaboration of at least two pilots in the cockpit. Thanks to progress in automation and telecommunication, aircraft manufacturers and aviation companies envision that a single pilot in the cockpit assisted by a pilot on the ground (i.e Single-Pilot Operation) could ensure fight operations while requiring less human resources. However, without appropriate collaboration tools, this situation of remote collaboration may lead to a degradation of the awareness of actions and attitudes between the two pilots (i.e. mutual awareness). In this paper, we propose to enrich the understanding of the remote collaboration problems of two pilots through a fine-grained analysis of mutual awareness needs. First, we describe awareness frameworks from the literature. Second, we identify awareness issues during a case study involving a crew of pilots in two distant fight simulators. Third, we refine the relevant awareness concepts through exploratory prototyping of collaborative tools. These prototypes are based on three scenarios involving specific awareness requirements including 1) visualizing the physiological state of the pilot on board during a non stabilized approach, 2) an emergency decision making, and 3) global awareness during a whole fight for a better efficiency of the ground assistant operator at the arrival. In this article our contribution is a refined study of the awareness needs adapted to the context of remote collaborative piloting, with the final objective of designing more appropriate tools
A gentle introduction to C code verification using the Frama-C platform: A Return of Experience from the Concorde project WP2
No full textThis document presents a process to verify C programs or librairies using the Frama-C verification tool. Frama-C allows to verify different types of properties on C code, such as the absence of runtime errors or more complex functional properties. The present document is the result of our work on the verification of a mathematical library of the Paparazzi autopilot and is intented to be used as a first guide to formal verification of C programs for Concorde users. In addition to provide a verification process, we also give Frama-C tips and tricks to help users and clarify some points that might not be clear in the official documentation of the tool
Optimisation des opérations aéroportuaires afin d'améliorer le transport intermodal de passagers
No full textInternational audienceOptimisation des opérations aéroportuaires afin d'améliorer le transport intermodal de passager
When BBR beats FEC coded CUBIC flows over SATCOM
No full textInternational audienceThis paper assesses the benefits of using Sliding Windows Forward error codes (SWF) to protect transport protocol sessions over a SATCOM link within IP tunnels. We consider two commonly deployed protocols and congestion control algorithms : TCP/CUBIC, currently deployed by default inside most of recent OS kernels and a QUIC/BBR implementation named Picoquic. Our objective is to evaluate the performance of these protocols in challenging SATCOM environments and to assess if SWF can contribute to improve their performance. We consider two different scenarios based on real loss mobility patterns played over the OpenSAND satellite emulator. Results show that using SWF tunnels can hide losses to a CUBIC server: this reduces the download time of 20MB by more than 90%. However, the main finding is that SWF does not contribute to the download time reduction for BBR, making useless its deployment. We conclude that the use of BBR over SATCOM could be an efficient way to perform communications over unreliable links, resulting from a high mobility context for instance, considering BBR flows are managed by an adequate QoS allocation
Analysis of clustering algorithms for by-zone machining of free-form surfaces
No full textEnd-milling of free-form surfaces on multi-axis CNC machines are complex and expensive operations involved in the production of many high-value parts, such as molds and stamping dies. To carry out such time-expensive operations, partitioning the surface into zones, in order to mill each zone with the most suitable parameters, is an approach gaining credit in recent years. Data clustering algorithms provide tools that appear to be naturally adapted to perform such a procedure. In this paper, is provided a fine analysis of various clustering algorithms, as well as the feature vectors and the metrics commonly used. Furthermore, the specific problems that may arise when applying clustering algorithms to free-form surfaces partitioning are presented and original solutions to deal with them are proposed
Estimating wind using a quadrotor
No full textInternational audienceThe aim of this work is to estimate the average wind influencing a quadrotor drone only based on standard navigation sensors and equations of motion. It can be used in several situation, including atmospheric studies, trajectory planning under environmental constraints, or as a reference for studying flights in shear layer. For this purpose, a small quadrotor drone with spherical shape has been developed. Flight data are recorded from telemetry during indoor and outdoor flight tests and are post-processed. The proposed solution is based on a calibration procedure with global optimization to extract the drag model and a Kalman Filter for online estimation of the wind speed and direction. Finally, an on-board implementation of the real-time estimation is demonstrated with real flights in controlled indoor environment
Thermodynamic modelling of the uranium-tellurium system. Estimation of the uncertainties by a Bayesian approach.
No full textInternational audienceUnder irradiation, the formation of fission products in the (U,Pu)O2 fuel with time has asubstantial effect on its chemistry. In particular, migration of the most volatile fission products (Cs,Te, I, Mo) from the center to the periphery of the fuel pellet is induced by the large radial thermalgradient. To predict the thermodynamic properties of the irradiated fuel, thermodynamic modelingof the complex multi-component (Cs-I-Te-Mo) (U-Pu) O system is performed using the CALPHADmethod. In this work, the thermodynamic assessment of the U Te sub-system is performed. Theliterature review reveals a lack of experimental data as well as scattering and inconsistency of someof the data. In particular, no thermodynamic data exist on the liquid. From this review, inputthermodynamic and phase diagram data are carefully selected. The Gibbs energy functions are thenadjusted by fitting these data. An overall good agreement is obtained with all the selected dataexcept for the enthalpy of formation for UTe which is underestimated by 13% by our model. Thiscould be due to an inconsistency between the enthalpy of formation and vapor pressure data. Ina second step, the uncertainties on the thermodynamic parameters and their propagation on thecalculated thermodynamic and phase diagram data are estimated using a Bayesian approach. Theanalysis shows that there are too many parameters (22) for too few data points (120 points). Theuncertainties are thus large on some of the calculated data. Moreover the inconsistency of someof the data and the lack of thermodynamic data for the liquid makes the model uncertain. Newexperimental data such as heat capacity, enthalpy of formation for the compounds, and chemicalpotentials or activities for the liquid phase would improve the reliability of our model. Measurementsof phase diagram data in the U UTe2 region are also required. However this work provides thefirst detailed uncertainty analysis of the U Te CALPHAD model. Moreover our approach, contraryto other Bayesian methods, provides an analytical posterior probability distribution and analyticalcredible intervals for the calculated thermodynamic quantities. It also speeds up the simulation ofthe uncertainty estimations on the phase diagram
Evaluating Aviation Emission Inefficiencies and Reduction Challenges with Electric Flights: Based on an analysis of flights from 2019 in the Dutch and French airspaces
No full textInternational audienceInefficiencies in flight operations, like deviations and non-optimal flight speed or altitude, are directly linked to flight emission inefficiencies. Quantifying these emission inefficiencies and studying potential mitigation strategies is certainly beneficial for the sustainability of the aviation industry. In this paper, we analyze emission inefficiencies in Dutch and French airspaces using flight data from 2019. The emission inefficiency analysis quantifies the excess carbon emissions for each flight by comparing its emissions with a set of optimal alternative trajectories. We find that around 19% of excess emissions existed in 2019 within the airspace of interest. We also study the potential reduction of emissions by replacing short-range flights with electric aircraft. We propose a simple electric aircraft energy model and relate that to emissions in electric generations in different countries. We find that besides the significant increase in air traffic demand caused by the limited capacities of electric flights, the emissions caused by electricity generation cannot be neglected. Significant reductions can only be achieved when emissions caused by electricity generation are low, as is the case currently in France. However, more emissions can be indirectly generated if the electricity used to power the future electric aircraft is itself produced from high emission sources, as is the case currently in the Netherlands. The paper also provides further insights and recommendations on the data sources, research approach, and future research for aviation sustainability
A Realistic Rotorcraft Noise Footprint Computation for Low-Noise Trajectory Optimization
No full textInternational audienceThis paper introduces recent developments in the computation of rotorcraft noise footprint, implemented in an Airbus Helicopters' internal software. The paper presents the main ingredients that have led to enhance the efficiency and accuracy of such noise footprint computation. This includes taking into account both the particularities of turns in noise emission and the influence of the wind on noise propagation. Furthermore, the software is able to assess a real traffic environmental impact, since computations are done within a realistic 3D simulation environment, taking into account both the curvature of the Earth and the topography of the ground. A variety of noise annoyance indicators can be computed thanks to the coupling with demographic and background noise data. Such realistic noise footprint computation is embedded in a tailored algorithmic scheme aiming at optimizing rotorcraft trajectories in such a way that their associated noise footprint is minimized. The proposed optimization approach has been tested on multiple real-world case studies, showing significant prospective noise reduction compared to reference trajectories
Concepts et outil pour l'informatique de l'interaction
No full textCurrent computing systems at the heart of critical systems, especially air transport, are characterized by multiple interactions, or strong couplings, between human operators, physical devices, and software. The design of such systems requires attention to the causal relationships between the different processes involved. Therefore, the task is no longer about designing input/output systems for which the algorithm must be created but specifying dynamic networks of interacting heterogeneous processes. As a result, these computing systems can no longer be easily understood within the classical theoretical framework: computability theory, inherited from the work of Turing and Church. Asynchronous events, independent execution flows, dynamic object creation, or passive waiting processes pose specific difficulties in modeling and practice. The primary objective of this thesis is to examine the possibility of a new theoretical framework for interactive computing to characterize it better, following a research program that aims at defining interaction. Probing the question about interaction is at the intersection of Human-Computer Interaction and involved programming practices, the epistemology of computing, and theoretical computer science. We are looking for an explanation of how interactive computing comes about and what mechanisms support it. We propose the concept of an execution model to build such an explanation. Among the requirements, we define the necessity of a component that we call a “causal orchestrator”. The consequence of this reflection is to motivate, guided by a study with programmers, an approach to tool a language dedicated to interaction. Through a set of interaction techniques within a code editor, Causette, we propose a way to support the programmer in understanding causal relationships between processes described in interaction programs.Les systèmes informatiques actuels au coeur des systèmes critiques, notamment le transport aérien, sont caractérisés par de multiples interactions, ou couplages forts, entre les opérateurs humains, les dispositifs physiques et les logiciels. La conception de ces systèmes nécessite de prêter attention aux relations causales entre les différents processus impliqués. Par conséquent, il ne s’agit plus de concevoir des systèmes d’entrée/sortie pour lesquels l’algorithme doit être créé, mais de spécifier des réseaux dynamiques de processus hétérogènes en interaction. En conséquence, ces systèmes informatiques ne peuvent plus être facilement appréhendés dans le cadre théorique classique : la théorie de la calculabilité, héritée des travaux deTuring et Church. Les événements asynchrones, les flux d’exécution indépendants, la création dynamique d’objets, ou encore les processus d’attente passive posent des difficultés spécifiques dans la modélisation et la pratique. L’objectif principal de cette thèse est d’examiner la possibilité d’un nouveau cadre théorique pourl’informatique interactive afin de mieux la caractériser, en suivant un programme de recherche qui vise à définir l’interaction. Sonder la question de l’interaction se situe à l’intersection entre l’interaction homme-machine et les pratiques de programmation impliquées, l’épistémologie de l’informatique et l’informatique théorique. Nouscherchons à expliquer ce qui rend possible l’interaction dans un système informatique, autrement dit nous nous interrogeons sur les mécanismes sous-jacents. Nous proposons le concept de modèle d’exécution pour construire une telle explication. Parmi les exigences, nous définissons la nécessité d’un composant que nous appelons un “orchestrateur causal”. La conséquence de cette réflexion épistémologique est de motiver, guidée par une étude auprès de programmeurs, une approche visant à outiller un langage dédié à l’interaction. A travers un ensemble de techniques d’interaction au sein d’un éditeur de code, Causette, nous proposons d’aider le programmeur à comprendre les relations causales d’un programme