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[en] In his speech on energy transition on 28 November last, the President of the Republic alerted us to the urgent need to 'develop more strongly the interconnections between France and the other European countries to improve our security of supply at lower cost'. While the issue of security of supply is very real, the fact remains that, in their current embryonic state, interconnections alone are not sufficient to ensure this security; worse, they are the source of new and unlikely blackout configurations
[fr]Lors de son allocution relative a la transition energetique, le 28 novembre dernier, le president de la Republique nous alertait sur l'urgence a 'developper plus fortement les interconnexions entre la France et les autres pays europeens pour ameliorer notre securite d'approvisionnement a moindre cout'. Si l'enjeu de la securite d'approvisionnement est bien reel, il n'en reste pas moins que dans leur fonctionnement embryonnaire actuel, les interconnexions ne peuvent suffire a elles seules a assurer cette securite; pire, elles sont a l'origine de nouvelles configurations de black-out improbables
[en] The issue of power quality is largely absent from discussions on energy, including those related to multi-annual energy programming, where the focus remains on security of supply, admittedly of critical importance. Clearly, blackouts or power outages, such as those that crippled Paris' Montparnasse railway station and its surrounds in late July 2018, tend to make the headlines. And a deep dive into this subject rapidly leads to complex considerations on the physics of electricity and network codes that the non-specialist may find daunting. Nevertheless, the growing dependence of our economies on digital technology and the emergence of intermittent renewable energies in the electricity mix are creating new challenges, with the question of power quality being a prime example. (authors)
[en] Energy efficiency can be considered as a central pillar of global warming mitigation, with important co-benefits, including productivity gains, resource conservation or national security. It is also a subject of controversy between engineers and economists, who have divergent conceptions of the notion of optimality that delineates energy efficiency potentials. Modern surveys hardly go back beyond the 1970s and do not fully explore the reasons and conditions for the persistent differences between economists' and engineers' views. This paper provides such a historical account, investigating the positioning of economic analysis in contrast to the technical expertise on key energy efficiency topics - the rebound effect, the energy efficiency gap, and green nudges, from the 19. century to the present day. It highlights the permanence and evolution in the relationship that economists have had with technical expertise. An extension of the current conceptual framework is finally provided to connect our historical findings with avenues for future research. (authors)
[en] Highlights: • Modeling the variability of the fuel costs over long term. • Modeling the Multi-Source System taking into account changes in fuel costs. • Limiting the number of starts of the diesel generator to increase its lifecycle. • Increasing the fuel cost can lead to an increase of 18% in the design cost. • Optimization algorithm favors the introduction of renewable sources. - Abstract: Multi-Source Systems combining renewable energy sources with diesel generators have been widely adopted in isolated sites. The economic and ecological aspects are very important for analyzing and evaluating such systems. In this paper, an optimization approach that includes the former aspects has been proposed. This approach takes into account the changes in the fuel cost over a lifecycle and the minimization of the greenhouse gas emission. The proposed method is based on three main steps. At first, a fuel cost progression model over a period of 40 years has been developed. Second, due to the complexity of such systems and in order to simplify the modeling, meta-models have been extracted by using the Design of Experiments technique. Finally, Single-Objective and Multi-Objective Optimization of the system based on economic and ecological criteria have been performed. The obtained results show that, changes in fuel costs have a significant influence on the sizing of the system. Indeed, the increase in fuel cost can lead to an increase of 18% in the design cost. The best solution on Pareto’s curve was found with a reduction rate in the fuel consumption between 30 and 35%. Furthermore, the optimization algorithm favors the introduction of renewable sources.
[en] The adaptive cruise control (ACC) system is currently one of the most common research topics in automotive industry. The ACC system tracks the velocity of preceding vehicle by adjusting the throttle angle and applying brake, whenever needed. This system is acknowledged for improving the fuel efficiency due to coordination between brake and throttle. Inappropriate switching between brake and throttle results in loss of energy that increases fuel consumption. To address aforesaid problem, novel coordinated switching controllers for the ACC system are proposed that enhances the fuel efficiency. Moreover, the proposed control strategies are compared for various traffic scenarios, and then, fuel economy is observed for the proposed control schemes. Fuel economy is investigated using switching control paradigm design; namely, the proportional–integral–derivative (PID) controller, adaptive proportional–integral–derivative (APID) controller, and fuzzy PID controller for actual nonlinear and linearized model of the ACC system for various traffic scenarios including stop and proposed control strategies are compared using performance indices for various traffic scenarios, such as CC, ACC, and ACC stop and go in order to show the validity of the design. Furthermore, the comparison among the PID, APID, and fuzzy PID control schemes is investigated to analyze fuel economy of the actual nonlinear CC and ACC system.
[en] To be effective, the energy transition cannot be achieved by national measures alone. It can only succeed if all decentralised actors embark on a transformation of urban housing, community facilities, mobility systems, food supply and, more generally speaking, the entire urban landscape. The city of Grande-Synthe was the French capital of biodiversity in 2010 (Natureparif). It has also been known since 2016 for its refugee camp (set up by Doctors Without Borders) and more recently due to its introduction of a guaranteed minimum social income. Grande-Synthe is an example of an organised evolution towards a more economical consumption and production of energies based on lower greenhouse gas emissions
[fr]Pour etre efficace, la transition energetique ne peut pas se contenter de mesures nationales. Elle ne peut reussir que si tous les acteurs decentralises s'engagent dans un processus de transformation qui touche a la fois l'habitat urbain, les equipements collectifs, les mobilites, l'alimentation et plus generalement l'organisation de la cite et de l'espace. La ville de Grande-Synthe dans le Nord, capitale francaise de la biodiversite en 2010 (Natureparif) et surtout connue depuis 2016 pour son camp de refugies (avec Medecins sans frontieres) et plus recemment par la mise en oeuvre d'un Revenu Minimum Social Garanti, est un exemple d'evolution maitrisee vers une consommation plus econome et une production d'energies moins emettrices de gaz a effet de serre
[en] Domestic uses of electricity now account for over half of electricity consumption in the French residential sector. The stakes are high but not yet very well known. Statistical estimates exist for the most energy-intensive uses but these are not sufficient to enable an accurate assessment of the current situation or to allow long-term scenarios to emerge. For several years, EDF's R and D teams have been conducting studies that combine surveys with energy modelling of uses in order to clearly and accurately depict consumption patterns. The article explores the principal results obtained in those studies. (authors)
[en] This paper employs a parallelized genetic algorithm in generating long-term bounded halo orbit and optimizing transfer trajectory from earth to it in the full ephemeris model. While the conventional gradient methods are lacking in precision as well as time-consuming, the parallel genetic algorithm (PGA) offers an access to large-scale computing based on the advanced hardware capability. A bounded halo orbit without any stationkeeping maneuver in five periods is obtained inside a defined pipe region in the ephemeris model. Transfer trajectory from earth to the obtained halo orbit is also investigated in this paper. By optimizing insertion impulses in the backward propagation and midcourse in the forward propagation, a transfer trajectory from earth to halo with least fuel consumption is generated. Furthermore, launch window is investigated based on the periodic variation about inclination of the injection point on the parking orbit. A mapping method from spatial space to subspace is introduced for solving the time delay and position deviation problem. The numerical method employed in this paper is of high accuracy based on large-scale computing capability as well as efficient without any analytical initial guess, which makes it extensive in designing these unstable libration point orbits.
[en] Fuel shortages and air pollution are two major incentives for improving the aerodynamics of vehicles. Reducing wake-induced aerodynamic drag, which is strongly dependent on flow topology, is important for improving fuel consumption rates which directly affect the environment. Therefore, a comprehensive understanding of the baseline flow topology is required to develop targeted drag reduction strategies. In this research, the near wake of a generic ground vehicle, a slant Ahmed model at a flow Reynolds number of , is investigated and its flow topology elucidated. The flow field of this canonical bluff body is extremely rich, with complex flow features such as spanwise trailing wake and streamwise C-pillar vortices. The flow is characterized through stereoscopic and tomographic velocity field measurements. The large-scale, horseshoe vortex structures in the trailing wake, conventionally denoted as A- and B-vortices, are found to vary in size and shape along the spanwise direction, which in turn influence the pressure distribution on the rear vertical surface. The longitudinal C-pillar vortices are found to extend far downstream and also influence the trailing wake structures through a complex, three-dimensional interaction. The accuracy and cost of obtaining volumetric information in this complex flow field, by means of volume reconstruction, through Stacked Stereoscopic-Particle Image Velocimetry (PIV) and Tomographic PIV are also investigated.
[en] Canada is a signatory to the Paris Accord and has set a target of reducing its emissions by 30% from 2005 levels by 2030. The production, transportation and use of Canada's abundant and diverse natural resources are an important part of the Canadian economy. Because these activities are energy-intensive and given the country's size and latitude, energy plays an important role in Canada's economic activity and emissions profile
[fr]Le Canada est signataire de l'Accord de Paris et s'est fixe comme objectif de reduire ses emissions de 30 % d'ici 2030 par rapport aux niveaux de 2005. La production, le transport et l'utilisation des ressources naturelles abondantes et diversifiees du Canada constituent une part importante de l'economie canadienne. Comme ces activites sont tres energivores et compte tenu de la surface du pays et de sa latitude, l'energie joue un role important dans l'activite economique du Canada et son profil d'emissions