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La gestion des reseaux de voies navigables devrait subir des modifications notables en raison d'une volonte d'accroitre le trafic fluvial dans un contexte de changement climatique. Ces nouvelles contraintes vont imposer une gestion adaptative et resiliente de la ressource en eau conduisant a une planification de sa repartition sur l'ensemble de ces reseaux. Une approche basee sur les MDP est proposee afin de repondre a cette problematique. Elle permet la coordination de plusieurs entites sur plusieurs pas de temps. Son utilisation sur un sous-reseau de voies navigables conduit a une minimisation de l'impact negatif lors d'evenements de montees des eaux ou de secheresse. Malgre des premiers resultats prometteurs, les mecanismes de passage a l'echelle permettant de considerer une application reelle ne sont pas totalement definis. Differentes approches proposees dans la litterature pour le passage a l'echelle sont discutees en degageant leurs avantages et limitations. Parmi elles, une modelisation distribuee est privilegiee et un nouvel algorithme de resolution est propose. Il est teste sur un sous-reseau de 7 biefs.

At the European scale, inland navigation waterway transport is considered as a competitive and environment friendly alternative to road and rail transport. This transport mode is promoting in north of France thanks to the building of the Canal Seine-Nord. The number of boats and the navigation scheduling will increase significantly. A big raise of the required water volume is waited. Overcoming this future navigation demand will be particularly challenging in a climate change context. Hence, a crucial step consists in investigating the resilience of the inland navigation networks considering the future navigation demand and the climate change impacts. The main objective of this paper is to present the tools dedicated to the resilience determination that is required to design adaptive management strategies of these networks. An integrated model is proposed to model the network and to identify and quantify water supplies and water intakes. Then, a generalized flow-based network is used to model the water volume dispatching. The water dispatching has to be optimized according to the network resilience against the increase of navigation demand, and against the decrease of available water resource particularly during drought periods. Due to the complex structure of the networks, uncertainties that are linked to the daily number of boat and to the available water resource, an interesting approach will consist in defining a distributed problem. Local virtual agents will be designed to manage each waterway section, and a global coordination process will guarantee the efficient management of the network. The tools are designed and tested considering the inland navigation network in north of France.

International audience; Inland waterways management is likely to go through heavy changes due to an expected traffic increase in a context of climate change. Those changes are going to requires adaptive and resilient management of the water resource. A representative model of the inland waterway has been proposed, using Markov decision processes to model the dynamic and uncertainties of the waterway. It is used to obtain an optimal plan for the distribution of the water on the network that takes into account the uncertainties arising for the operation of such networks. A subnetwork of the Hauts-de-France is modeled using this approach based on real data of traffic and water levels. The produced plans are tested on different scenarios under expected and unexpected conditions of traffic and climate to observe the quality and resilience of the generated plan during its execution. Simulations will show the advantages and limitations of such a modeling of the inland waterway network.

International audience; Inland navigation transport takes part in the Trans-European network program (TEN-T *), which aims at promoting this mode of transport by creating favorable conditions for the further development of this sector. The NAIADES † Action Program comprises numerous actions and measures to boost transport on inland waterways. Among these actions, the infrastructure issue is dealt with. It requires the inventory of the existing infrastructure and the study of the possible effects of the expected climate change. This was one of the objectives of the GEPET-Eau ‡ project (2013-2016), which led to the proposal of multi-scale modeling approaches and adaptive and predictive control architectures. The resilience of inland waterways against the increase of navigation demand and the expected extreme drought and flood events was studied by considering deterministic models. The proposed architecture is suitable to consider two scales of space and time to optimize the water resource allocation among the inland networks and to guarantee the navigation conditions by proposing advanced control and fault detection tools. These approaches, which were designed by considering inland waterways in the north of France, are still being improved. Indeed, it is firstly necessary to consider all the uncertainties that are inherent to large-scale and environmental systems. Secondly, the advanced control and fault detection tools require further development to deal with the very complex dynamics that characterize inland waterways. The main objective of this work is to present the current state of the tools that have been developed in order to study and manage the inland waterways in a climate change context. The global framework that allows describing the link between these two management scales will be detailed. The water resource allocation approach can be based on three different techniques: the Constraint Satisfaction Problem (CSP), the quadratic optimization and the Markov Decision Process (MDP). The MDP-based approach will be emphasized due to its suitability to study complex systems with uncertainties, and its main advantages and drawbacks will be discussed and compared to the other techniques. Advanced control and fault detection tools require an in-depth knowledge of the inland waterway dynamics. Characteristics of navigation reaches, i.e. slope, resonance phenomenon, uncontrolled inputs and interconnections, need to be taken into account. A big effort has been made to improve the modeling step of the navigation reaches by considering the IDZ (Integrator Delay Zero) model. The designed tools are based on this accurate model, and they aim at improving the water level control of each reach of the inland waterways and at performing predictive maintenance strategies by detecting, isolating and forecasting faults on sensors and actuators (limnimeters, gates, locks, etc.). The designed management tools will be presented by considering a part of the real inland navigation network in the north of France. Perspectives and future developments will be described.

International audience; Inland waterway networks are likely to go through heavy changes due to a will in increasing the boat traffic and to the effects of climate change. Those changes would lead to a greater need of an automatic and intelligent planning for an adaptive and resilient water management. A representative model is proposed and tested using MDPs with promising results on the water management optimization. The proposed model permits to coordinate multiple entities over multiple time steps in order to avoid a flood in the waterway network. However, the proposed model suffers a lack of scalability and is unable to represent a real case application. The advantages and limitations of several approaches of the literature are discussed according to our case study.

A first attempt to numerically simulate the broadband noise transmitted through and radiated from a turbofan bypass duct is presented in this paper. Turbulent source assessment on the fan rows is left out here, and a generic power spectral density of in-duct acoustic pressure is imposed as an input to a computational aeroacoustics simulation performed using a time-domain Euler solver. The acoustic field is expanded over usual Fourier-Bessel modes, and the prescribed spectrum is re-generated by assuming an equi-modal energy distribution. The broadband noise behavior is modeled by introducing a random phase when imposing each acoustic mode and by performing a quadratic averaging of the numerical solution over a few independent runs. This broadband-like source generation approach is firstly validated for a semi-infinite annular duct with uniform flow by comparison with analytical solutions. Decrease of the statistical errors depending on the number of run is checked showing that at least 10 runs have to be considered. The exhaust radiation problem from an idealized nozzle in uniform and shear mean flow is then investigated and validated (for single mode case) by comparison to a Wiener-Hopf based solution. Far-field predictions are obtained by coupling the Euler code with a Kirchhoff integral. Computed results appear to be stable and accurate even in the presence of vorticity waves created in the shear layer. Expected shear effect, leading to a deviation of the directivity lobe from the duct axis, is confirmed for broadband noise. Then, the computation method is applied to a realistic nozzle, including a RANS solution providing the mean flow. The only problem arising is the computational cost resulting in a limitation of high frequency range limited here to 2 3 kHz (with around 600 propagating modes). Anyway, computed far-field directivities relative to idealized and realistic nozzle cases with similar input conditions are found to be rather close up to 90 o of radiation angle.

In this paper a new equation system is presented: Euler Equation in Perturation 2.5-D. It allows the simulation of spinning acoustic mode propagation with 2-D meshes. First, the building of the system is presented. Then the equation system is validated on an academic conguration. Numerical results are in very good agreement with the analytical solutions. At last, it is applied with a non-uniform mean o w and on a nozzle geometry. It is observed that depending on the frequency of the spinning mode, the simulation is stable or not. When the simulation fails, highly amplied instabilities in the shear layer can be observed. When the simulation is stable, results are in good agreement with those obtained by using a 3-D equation system.

This paper deals with the numerical study of installation effects, a subject which is relevant of the more general purpose of the aircrafts noise prevision and reduction. As an example of installation effects, we study here the potential shielding effect that an empennage airfoil could offer to the reduction of the aft fan noise produced by a coaxial engine. Because the numerical simulations constitute an as powerful as cheap tool of investigation, we use for it a solver developed at ONERA, the sAbrinA CFD/CAA platform. In particular, we take benefits from an innovative overlapping method recently implemented in it - a method which allows handling more easily the solid obstacles to be considered. As an illustration of both the methodology and the tool, a full-3D aft fan noise propagation is then computed over an installed (over an airfoil) engine.

International audience; Inland waterway management should undergo heavy changes due to a commitment to increase the waterway traffic in a context of climate change. These new constraints will impose an adaptive and resilient management of the water resource. The aim is to plan optimally the water resource distribution over the integrity of the inland waterway network, while taking into account the uncertainties arising from their operation. Due to the large size of waterways, a centralized modeling would not be able to represent an entire network. A distributed Markov Decision Process modeling of inland waterways associated with a resolution algorithm is proposed to allow full scalability, at the cost of optimality. The proposed approach is tested on a subnetwork composed of 7 reaches.

National audience; Inland waterway networks are likely to go through heavy changes due to a will in increasing the boat traffic and to the effects of climate change. Those changes would lead to a greater need of an automatic and intelligent planning for an adaptive and resilient water management. A representative model of the network is proposed and tested using MDPs with promising results on the water management optimization. The proposed model permits to coordinate multiple entities over multiple time steps in order to avoid a flood and drought, in the waterway network. However, the proposed model suffers a lack of scalability and is unable to represent a real case application. The advantages and limitations of several approaches of the literature are discussed according to our case study.; Les réseaux de voies navigables devraient subir des changements importants en raison d'une volonté d'augmenter le trafic naval et des effets du changement climatique. Ces changements nécessitent une gestion adaptative et résiliente de la ressource en eau et requièrent donc une planification plus intelligente. Un modèle représentatif du réseau, utilisant des MDPs, est proposé et testé afin d'optimiser la gestion de l'eau. Il fournit des résultats prometteurs, le modèle proposé permet de coordonner plusieurs entités sur plusieurs pas de temps de façon à éviter les inondations et sécheresses dans le réseau. Cependant, la solution proposée ne permet pas de passer à l'échelle et n'est pas utilisable dans une application réelle. Les avantages et limitations de plusieurs approches de la littérature qui pourrait permettre de passer à l'échelle sont présentés et discutés sous le prisme de notre étude de cas.