Search results for "Énergie"
showing 10 items of 37 documents
Timing and patterns of the ENSO signal in Africa over the last 30 years: insights from normalized difference vegetation index data.
2014
Abstract A more complete picture of the timing and patterns of the ENSO signal during the seasonal cycle for the whole of Africa over the three last decades is provided using the normalized difference vegetation index (NDVI). Indeed, NDVI has a higher spatial resolution and is more frequently updated than in situ climate databases, and highlights the impact of ENSO on vegetation dynamics as a combined result of ENSO on rainfall, solar radiation, and temperature. The month-by-month NDVI–Niño-3.4 correlation patterns evolve as follows. From July to September, negative correlations are observed over the Sahel, the Gulf of Guinea coast, and regions from the northern Democratic Republic of Congo…
Study of economic availability related to rare metals in the context of the energy transition
2014
A growing number of academic studies and international organizations reports have noticed an increasing dependency of new energy technologies on a specific class of natural resources often called minor metals. For several years, worries about economic availability of these metals in order to realize the energy transition have appeared. This thesis aims at underline the broader risks and constraints involved by general use of these metals in new energy technologies. A first part of this thesis is devoted to theories and indicators related to the depletion of non renewable resources. This part also shows that minor metals share many characteristics and that they can form a group of metal cons…
The risk management in the international contracts of marine renewable energy : focus on offshore wind farms
2022
At a time when climate change is becoming the main concern, the renewable energy sector is developing extremely rapidly. In order to add other sources to the existing ones and to increase electricity production while ensuring its stability, the sea has quickly been considered as an attractive alternative. However, the creation of a new industry is a major challenge and marine renewable energy projects are very expensive and risky. The concept of risk was created specifically regarding the management of human activities at sea. The example of offshore wind energy allows us to go back to the origins of the notion of risk by considering it from the point of view of the company, and to analyse …
The vehicle as a source and consumer of information : collection, dissemination and data processing for sustainable mobility
2014
Today, vehicles have become more sophisticated, intelligent and connected. Indeed, they are equipped with sensors, radars, GPS, communication interfaces and high processing and storage capacities. They can collect, process and communicate information related to their working conditions and their environment forming a vehicular network. The incorporation of communication technologies on vehicles garnered a huge attention of industry, government authorities and standardizations organizations and opened the way for innovative applications that revolutionized the automotive market with the main goals to ensure safety on roads, increase transport efficiency and provide comfort to drivers and pas…
Synthesis and study of new precursors for bimodal optic/PET or optic/SPECT imaging
2014
This thesis was performed at the Institut de Chimie Moléculaire de d’Université de Bourgogne (France) and in the Département de chimie de l’Université de Sherbrooke (Québec). The aim of this work was to design new BODIPY derivatives in order to obtain optimal properties for in vivo bimodal optical/PET or SPECT imaging. The modifications concern the hydrosolubilisation of these organic dyes, as well as the shifting of the absorption and emission bands toward the therapeutic window, where the light is less attenuated by biological tissues. Solutions allowing the bioconjugation of BODIPY on a bombesin derivative, a peptide which targets receptors surexpressed in tumor cells, were also investig…
Approche géographique des approvissionnements en plaquettes foréstières des chaufferies du secteur collectif/tertiaire : application au Pays Loue-Lis…
2011
In a context of strong increase of fuelwood demand in the collective sector, the supply issue becomes central to all stakeholders, raising many issues relating to land and forestry planning, local development, environment ... Meanwhile, questions emerge: how much energy can be mobilized sustainably? Does the spatial and structural configuration of forests influence the supply process? Do we seek to minimize transport distances? Can we observe spatial competition between the boilers ? To understand the current organization of supplies, we analyzed two sets of data traceability of wood chips. Then, we have developed a model of local supply basins, considering constraints of renewability of th…
Annales des travaux des auditeurs de l'IHEDN 2007 : "L'énergie au XXIe siècle"
2007
CD rom; International audience
Energy minimization of single input orbit transfer by averaging and continuation
2006
AbstractThis article deals with the transfer between Keplerian coplanar orbits using low propulsion. We focus on the energy minimization problem and compute the averaged system, proving integrability and relating the corresponding trajectories to a three-dimensional Riemannian problem that is analyzed in details. The geodesics provide approximations of the extremals of the energy minimization problem and can be used in order to evaluate the optimal trajectories of the time optimal and the minimization of the consumption problems with continuation methods. In particular, minimizing trajectories for transfer towards the geostationary orbit can be approximated in suitable coordinates by straig…
Modeling and Coordination of interconnected microgrids using distributed artificial intelligence approaches
2019
As renewable sources penetrate the current electrical system to relief global warming and energy shortage, microgrid (MG) emerges to reduce the impact of intermittent generation on the utility grid. Additionally, it improves the automation and intelligence of the power grid with plug-and-play characteristics. Inserting more MGs into a distribution network promotes the development of the smart grid. Thus MG networks existing in the power system are in prospect. Coordinating them could gain a system with high reliability, low cost, and strong resistance to electrical faults. Achieving these profits relies on developed technologies of communication, control strategy, and corresponding algorith…
Network architectures and energy efficiency for high performance data centers
2017
The increasing trend to migrate applications, computation and storage into more robust systems leads to the emergence of mega data centers hosting tens of thousands of servers. As a result, designing a data center network that interconnects this massive number of servers, and providing efficient and fault-tolerant routing service are becoming an urgent need and a challenge that will be addressed in this thesis. Since this is a hot research topic, many solutions are proposed like adapting new interconnection technologies and new algorithms for data centers. However, many of these solutions generally suffer from performance problems, or can be quite costly. In addition, devoted efforts have n…