Applied Methods Validating Aircraft Flight Path Optimization. Theoretical and Experimental Considerations

Flight path optimization is designed for minimizing aircraft fuel consumption and the environmental impact around airports. This paper gives models, numerical methods and algorithms validating optimized aircraft flight paths and comparisons between methods are carried out. The OCP problem is transformed into new constrained equalities. This constitutes an original dynamic system extension where subsystems are linked to the original dynamics via algebraic coupling equations. A feedback control is used. We obtained two possible optimized flight path solutions. In particular, they favor fuel consumption saving (−34% to −20%). Two A320 Airbus practiced the two obtained solutions six times each. In-flight analysis of their FDR and experimental measurement on the ground showed a 5.7 dB reduction of noise. They also confirmed a fuel consumption reduction of −18% in comparison with ICAO empirical procedures. Differences between the theoretical and in-flight data are due to theoretical assumptions and the use of a rough model of fuel consumption. No incident of safety, comfort or extra workload of the pilots was observed. This optimized flight path validation could benefit both airlines and communities. These trajectories are more suitable for the air traffic management system and can be interfaced with the in-flight management system

Managed groundwater recharge at the farm scale in pre-Saharan Morocco

The oases of the pre-Saharan basin of Wadi Ferkla in southeastern Morocco receives low and erratic rainfall (annual average of 141 mm and inter-annual standard deviation of 70 mm). From the 1980s, surface water and groundwater are increasingly used due to the expansion of irrigation, mainly along two wadis, namely Wadis Ferkla and Satt originating in the High-Atlas and the Anti-Atlas Mountains, respectively. Their flows reach the Ferkla's irrigated perimeters only when the volume of the flood events exceed upstream evaporation, withdrawals and riverbed's infiltration. Nowadays, these irrigated perimeters exert significant pressure on groundwater resources, through numerous drillings equipped with pumping systems, most of them being powered by solar energy. This increasing water demand situation incentivizes individual farmers to design and implement innovative techniques to increase water access for their farms. For instance, the spreading of floodwaters – an ancestral and collective irrigation practice in traditional oases – is currently being modernized by individual farmers. The new technique consists in partially diverting flood flows into earthen basins. The stored water either infiltrates to recharge local aquifers, or is pumped for flood irrigation of date palms. An experimental protocol was set up to characterize groundwater recharge below one of these on-farm basins equipped with a recharge well. Barometric probes were installed in the basin, in the recharge well and in neighboring boreholes to automatically monitor water levels. A topographic survey of the monitoring points and of the basin aimed at deriving piezometric levels from water levels measurements and estimating the height-surface-volume curves of the basin. After 7 months of continuous monitoring, 3 flood events were recorded. The establishment of the basin water balance at a fine time-resolution allowed estimating its different components including the infiltration rate influencing groundwater recharge. An analytical modeling of this process was developed to assess its effect on groundwater level variations. This approach aims to contribute to a broader reflection on securing water management in this fragile oasis ecosystem.</p

Two-Aircraft Acoustic Optimal Control Problem: SQP algorithms

This contribution aims to develop an acoustic optimization model of flight paths minimizing two-aircraft perceived noise on the ground. It is about minimizing the noise taking into account all the constraints of flight without conflict. The flight dynamics associated with a cost function generate a non-linear optimal control problem governed by ordinary non-linear differential equations. To solve this problem, the theory of necessary conditions for optimal control problems with instantaneous constraints is well used. This characterizes the optimal solution as a local one when the newtonian approach has been used alongside the optimality conditions of Karush-Kuhn-Tucker and the trust region sequential quadratic programming. The SQP methods are suggested as an option by commercial KNITRO solver under AMPL programming language. Among several possible solution, it was shown that there is an optimal trajectory (for each aircraft) leading to a reduction of noise levels on the ground.Cette contribution vise à développer un modèle mathématique d’optimisation acoustique des trajectoires de vol de deux avions en approche et sans conflit, en minimisant le bruit perçu au sol. Toutes les contraintes de vol des deux avions sont considérées. La dynamique de vol associée au coût génère un problème de contrôle optimal régis par des équations différentielles ordinaires non-linéaires. Pour résoudre ce problème, la théorie des conditions nécessaires d’optimalité pour des problèmes de commande optimale avec contraintes instanées est bien développée. Ceci se caractérise par une solution optimale locale lorsque l’approche newtonienne est utilisée en tenant compte des conditions d’optimalité de Karush-Kuhn-Tucker et la programmation quadratique séquentielle globalisée par région de confiance. Les méthodes SQP sont proposées comme option par KNITRO sous le langage de programmation AMPL. Parmi plusieurs solutions admissibles, il est retenu une trajectoire optimale menant à une réduction du niveau de bruit au sol

Two-Aircraft Acoustic Optimal Control Problem: SQP algorithms

International audienceThis contribution aims to develop an acoustic optimization model of flight paths minimizing two-aircraft perceived noise on the ground. It is about minimizing the noise taking into account all the constraints of flight without conflict. The flight dynamics associated with a cost function generate a non-linear optimal control problem governed by ordinary non-linear differential equations. To solve this problem, the theory of necessary conditions for optimal control problems with instantaneous constraints is well used. This characterizes the optimal solution as a local one when the newtonian approach has been used alongside the optimality conditions of Karush-Kuhn-Tucker and the trust region sequential quadratic programming. The SQP methods are suggested as an option by commercial KNITRO solver under AMPL programming language. Among several possible solution, it was shown that there is an optimal trajectory (for each aircraft) leading to a reduction of noise levels on the ground.Cette contribution vise à développer un modèle mathématique d’optimisation acoustique des trajectoires de vol de deux avions en approche et sans conflit, en minimisant le bruit perçu au sol. Toutes les contraintes de vol des deux avions sont considérées. La dynamique de vol associée au coût génère un problème de contrôle optimal régis par des équations différentielles ordinaires non-linéaires. Pour résoudre ce problème, la théorie des conditions nécessaires d’optimalité pour des problèmes de commande optimale avec contraintes instanées est bien développée. Ceci se caractérise par une solution optimale locale lorsque l’approche newtonienne est utilisée en tenant compte des conditions d’optimalité de Karush-Kuhn-Tucker et la programmation quadratique séquentielle globalisée par région de confiance. Les méthodes SQP sont proposées comme option par KNITRO sous le langage de programmation AMPL. Parmi plusieurs solutions admissibles, il est retenu une trajectoire optimale menant à une réduction du niveau de bruit au sol

Non-exhaust particle emissions under various driving conditions: Implications for sustainable mobility

International audienceNon-exhaust particle (NEP) emissions from road traffic contribute significantly to Particulate Matter (PM) pollution in urban areas. The primary objective herein is to develop the knowledge required to move toward more sustainable mobility. NEP emissions are studied by means of complementary experiments on chassis dynamometers, on test tracks and at the roadside. Laboratory tests demonstrate that brake wear particles (BWP) emissions can change with braking force and frequency. A brake pad temperature threshold exists, above which the rate of ultrafine particle emissions is quite high. Below this threshold, the BWP emissions are dominant in the accumulation and coarse modes. Test track measurements have demonstrated that tire-road contact particle (TRCP) emissions considerably modify the atmospheric PM background especially for the supermicron fraction. Their number size distribution highlighted an ultrafine and accumulation modes centered at about 40 nm and 200 nm, respectively. The TRCP level increases with vehicle speed and during the acceleration and deceleration phases. Roadside measurements in the urban environment confirm the presence of NEP in significant proportions, in both the accumulation and coarse modes. The chemical composition of NEP differs depending on the size mode: BWP mainly stem from the degradation of brake pad lining materials, while TRCP are a mixture of tire tread wear and re-suspended dust. The presence of Fe-rich particles nevertheless serves as a good indicator of the NEP contribution to PM at the roadside. Lastly, in considering the parameters influencing NEP emissions, a series of recommendations are offered in order to achieve a more sustainable mobility